<PAGE>
   
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON APRIL 23, 1997
    
 
                                                      REGISTRATION NO. 333-20511
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------
 
   
                                AMENDMENT NO. 2
                                       TO
                                   FORM SB-2
    
 
                             REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933
 
   
                                       ON
                                    FORM S-4
    
                                ---------------
 
                                ANTIVIRALS INC.
          (Name of small business issuer as specified in its charter)
 

<TABLE>
<S>                              <C>                            <C>
            OREGON                           2834                  93-0797222
 (State or other jurisdiction    (Primary Standard Industrial    (IRS Employer
              of                 Classification Code Number)     Identification
incorporation or organization)                                      Number)
</TABLE>

 
                          ONE SW COLUMBIA, SUITE 1105
                             PORTLAND, OREGON 97201
                                 (503) 227-0554
 
         (Address, including zip code, and telephone number, including
            area code, of registrant's principal executive offices)
 
                             DENIS R. BURGER, PH.D.
                            CHIEF EXECUTIVE OFFICER
                                ANTIVIRALS INC.
                         ONE S.W. COLUMBIA, SUITE 1105
                             PORTLAND, OREGON 97258
                                 (503) 227-0554
 
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
 
- --------------------------------------------------------------------------------
 
                          ANTI-GENE DEVELOPMENT GROUP
          (Name of small business issuer as specified in its charter)
 

<TABLE>
<S>                              <C>                            <C>
            OREGON                           2834                  93-0797108
 (State or other jurisdiction    (Primary Standard Industrial    (IRS Employer
              of                 Classification Code Number)     Identification
incorporation or organization)                                      Number)
</TABLE>

 
                             3107 NW NORWOOD PLACE
                            CORVALLIS, OREGON 97330
                                 (541) 753-3133
 
         (Address, including zip code, and telephone number, including
            area code, of registrant's principal executive offices)
 
                           JAMES E. SUMMERTON, PH.D.
                                GENERAL PARTNER
                          ANTI-GENE DEVELOPMENT GROUP
                             3107 NW NORWOOD PLACE
                            CORVALLIS, OREGON 97330
                                 (541) 753-3133
 
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
 
                         ------------------------------
 
                                   COPIES TO:
                       JACK W. SCHIFFERDECKER, JR., ESQ.
                            BYRON W. MILSTEAD, ESQ.
                    ATER WYNNE HEWITT DODSON & SKERRITT LLP
                          222 SW COLUMBIA, SUITE 1800
                             PORTLAND, OREGON 97201
                           TELEPHONE: (503) 226-1191
 
                         ------------------------------
 
    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after this Registration Statement becomes effective.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

<PAGE>
   
    If any of the securities being registered on this Form are to be offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box. / /
    
 
                        CALCULATION OF REGISTRATION FEE
 

<TABLE>
<CAPTION>
                                                                                 PROPOSED
                                                               PROPOSED          MAXIMUM
        TITLE OF EACH CLASS OF             AMOUNT TO BE    MAXIMUM OFFERING     AGGREGATE         AMOUNT OF
      SECURITIES TO BE REGISTERED           REGISTERED     PRICE PER SHARE    OFFERING PRICE   REGISTRATION FEE
<S>                                      <C>               <C>               <C>               <C>
Common Stock(1)                              667,436             (2)           $ 3,121,965        $  946.05
Common Stock(3)                              625,537             (4)            2,852,449           864.38
Common Stock(5)                             3,569,030            (6)            21,414,180         6,489.15
Promissory Notes                            3,750,965           $1.00           3,750,965          1,136.66
Limited Partnership Units(7)                  568.67             (8)            2,852,449           864.38
Total                                                                          $33,992,008        $10,300.62
</TABLE>

 
(1) Represents shares of Common Stock underlying a right to rescind being
    offered to certain purchasers of Common Stock of the Company.
 
(2) The shares of Common Stock that are subject to the rescission offer were
    sold at prices ranging from $4.56 to $4.95 per share.
 
(3) Represents shares of Common Stock underlying a right to rescind being
    offered to certain persons who exchanged units of limited partnership
    interest in the Anti-Gene Development Group at a ratio of 1100:1 on April
    29, 1993.
 
(4) The shares of Common Stock have been valued at $4.56 per share based on the
    Company's sale of shares of Common Stock for $4.56 per share on April 29,
    1993, contemporaneous with its exchange offering.
 
(5) Represents shares of Common Stock to be pledged by certain officers,
    directors and principal shareholders of the Company to secure the Company's
    payment of the Promissory Notes.
 
(6) The shares of Common Stock to be pledged have been valued at $6.00 per share
    based upon the initial value established for such shares in the Pledge
    Agreement.
 
(7) Represents units of limited partnership interest in the Anti-Gene
    Development Group which may be issued to certain persons who exchanged units
    of limited partnership interest in the Anti-Gene Development Group at a
    ratio 1:1100 for shares of the Company's Common Stock on April 29, 1993.
 
   
(8) The units of limited partnership interest have been valued at $5,016 per
    unit based on the exchange ratio and the Company's sale of shares of Common
    Stock for $4.56 per share on April 29, 1993, contemporaneous with the
    exchange offering.
    
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT THAT SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL HEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.

<PAGE>
                                   ANTIVIRALS
                          ANTI-GENE DEVELOPMENT GROUP
 
                            ------------------------
 
   
                             CROSS REFERENCE SHEET
                 SHOWING LOCATION IN PROSPECTUS OF INFORMATION
                         REQUIRED BY ITEMS OF FORM S-4
    
 
                            ------------------------
 
   

<TABLE>
<CAPTION>
FORM S-4 ITEM NUMBER AND CAPTION                                                    PROSPECTUS CAPTION
- -----------------------------------------------------------------  ----------------------------------------------------
<C>        <S>                                                     <C>
       1.  Forepart of the Registration Statement and Outside
             Front Cover Page of Prospectus......................  Outside Front Cover Page
       2.  Inside Front and Outside Back Cover Pages of
             Prospectus..........................................  Inside Front Cover Page; Outside Back Cover Page
       3.  Risk Factors, Ratio of Earnings to Fixed Charges and
             Other Information...................................  Prospectus Summary; The Rescission Offer; Risk
                                                                     Factors
       4.  Terms of the Transaction..............................  Prospectus Summary; The Rescission Offer
       5.  Pro Forma Financial Information.......................  Not Applicable
       6.  Material Contracts with Company Being Acquired........  Not Applicable
       7.  Additional Information Required for Reoffering by
             Persons and Parties Deemed to be Underwriters.......  Not Applicable
       8.  Interests of Named Experts and Counsel................  Not Applicable
       9.  Disclosure of Commission Position on Indemnification
             for Securities Act Liabilities......................  Not Applicable
      10.  Information with Respect to S-3 Registrants...........  Not Applicable
      11.  Incorporation of Certain Information by Reference.....  Not Applicable
      12.  Information with Respect to S-2 or S-3 Registrants....  Not Applicable
      13.  Incorporation of Certain Information by Reference.....  Not Applicable
      14.  Information with Respect to Registrants Other than S-3
             or S-2 Registrants..................................  Not Applicable
      15.  Information with Respect to S-3 Companies.............  Not Applicable
      16.  Information with Respect to S-2 or S-3 Companies......  Not Applicable
      17.  Information with Respect to Companies Other than S-3
             or S-2 Companies....................................  Summary Financial Data of the Company; Dividend
                                                                     Policy of the Company; Capitalization of the
                                                                     Company; Selected Financial Data of the Company;

                                                                     Management's Discussion and Analysis of Financial
                                                                     Condition and Results of Operations of the
                                                                     Company; Business of the Company; Management of
                                                                     the Company; Certain Transactions of the Company
                                                                     and AGDG; Principal Shareholders of the Company;
                                                                     Description of Securities of the Company; Shares
                                                                     of the Company Eligible for Future Sale; Selected
                                                                     Financial Data of AGDG; Management's Discussion
                                                                     and Analysis of Financial Condition and Results of
                                                                     Operations of AGDG; Business of AGDG; Management
                                                                     of AGDG; Description of Securities of AGDG;
                                                                     Principal Interest Holder of AGDG; Legal Matters;
                                                                     Experts
      18.  Information if Proxies, Consents or Authorizations Are
             to Be Solicited.....................................  Not Applicable
      19.  Information if Proxies, Consents or Authorizations Are
             Not to Be Solicited.................................  Not Applicable
</TABLE>

    

<PAGE>
PROSPECTUS
 
                  RESCISSION OFFER TO CERTAIN SHAREHOLDERS OF
                                ANTIVIRALS INC.
 
    AntiVirals, Inc. (the "Company") hereby offers to certain purchasers of the
Company's Common Stock, $0.0001 par value (the "Common Stock"), the right to
rescind their acquisition of the Company's Common Stock and to receive in
exchange for the Common Stock relinquished to the Company a payment equal to the
purchase price of such Common Stock, or the return of the units of limited
partnership interest in the Anti-Gene Development Group exchanged for such
Common Stock, each plus interest at the applicable statutory rate in the state
in which they reside (the "Statutory Rate") from the date of purchase or
exchange, or if the Common Stock has been disposed of at a loss, the difference
between the purchase price of such Common Stock and the price received upon
disposition plus interest at the Statutory Rate from the date of disposition
(the "Rescission Offer"). The securities that are the subject of the Rescission
Offer include 667,436 shares of Common Stock that were sold between October,
1990 and March, 1994 at prices ranging from $4.56 per share to $4.95 per share
and 625,537 shares of Common Stock that were issued during April, 1993 in
exchange for units of limited partnership interest in the Anti-Gene Development
Group (the "Subject Securities"). This information has been adjusted to reflect
a 1-for-3 reverse split of the Company's Common Stock which was completed on
November 4, 1996. The Rescission Offer is made only to persons who purchased the
Subject Securities from the Company by payment or exchange (each, an "Eligible
Offeree") and is not available with respect to any other securities purchased
from the Company or to persons who purchased the Company's securities from any
other person. During 1992, the Company's management conducted a review of its
past operations, including capital-raising activities. At that time, although
management did not identify any specific, material failures to comply with
obligations imposed on the Company by applicable federal and state securities
laws, management concluded that the record with respect to such activities was
sufficiently incomplete that a conclusion could not be drawn with substantial
certainty that such obligations were complied with in all material respects.
Notwithstanding this conclusion, a review of the Company's securities offering
documents, prepared in connection with sales of Common Stock by the Company
between October, 1990 and March, 1994, indicated that the Company had omitted to
disclose, or provided only limited disclosure with respect to, this conclusion
to certain prospective purchasers of the Subject Securities. The offer and sale
of the Subject Securities therefore may not have been undertaken in compliance
with the Securities Act of 1933, as amended (the "1933 Act"), the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), the Oregon Securities Law
or the securities laws of other states (collectively, the "Securities Laws").
The Rescission Offer is being made in order to limit, so far as may be
permissible under the Securities Laws, the potential liability of the Company
with respect to the offer and sale of the Subject Securities. The Securities and
Exchange Commission takes the position that liabilities under the federal
securities laws are not terminated by making a Rescission Offer. See "The
Rescission Offer."
 
                                                        (CONTINUED ON NEXT PAGE)
 
                            ------------------------
 
    NEITHER THE COMPANY NOR ITS BOARD OF DIRECTORS MAKE ANY RECOMMENDATION TO
ANY SHAREHOLDER AS TO WHETHER TO ACCEPT THE RESCISSION OFFER OR TO RETAIN THE
COMMON STOCK PURCHASED FROM THE COMPANY. EACH SHAREHOLDER MUST MAKE HIS OWN
DECISION AS TO WHETHER TO ACCEPT THE RESCISSION OFFER.
 
    The Rescission Offer Will Expire at 5:00 P.M., Portland, Oregon time, on
April 30, 1997.
 
  THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE UNITED STATES
   SECURITIES AND EXCHANGE COMMISSION NOR HAS THE COMMISSION PASSED UPON THE
      ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
      CONTRARY IS A CRIMINAL OFFENSE UNDER THE LAWS OF THE UNITED STATES.
 
               The date of this Prospectus is            , 1997.

<PAGE>
    The Company will pay to each Eligible Offeree who accepts the Rescission
Offer an amount equal to the consideration paid to the Company by the Eligible
Offeree for the repurchased securities or return the units of limited
partnership interest in the Anti-Gene Development Group, together with interest
from the date of purchase at the Statutory Rate (collectively, the "Rescission
Price"). The Rescission Price will be paid promptly after April 30, 1997 (the
"Expiration Date"). Eligible Offerees who obtained shares of Common Stock
through the exchange of units of the Anti-Gene Development Group will be
tendered units of the Anti-Gene Development Group and will be paid interest at
the Statutory Rate in cash or notes as hereafter provided. The Rescission Price
will be paid in cash to all other Eligible Offerees; provided, however, that to
the extent that securities with an aggregate cash Rescission Price in excess of
$1,500,000 are tendered to the Company in response to the Rescission Offer, the
Company will issue to rescinding securityholders in the state of Oregon and
Colorado a portion of the Rescission Price in the form of secured promissory
notes of the Company bearing interest at the rate of 9% per annum and with
maturities of 18 months to 36 months. Each such Eligible Offeree will cease to
be a shareholder of the Company with respect to any tendered shares upon payment
by the Company of the Rescission Price. See "The Rescission Offer."
 
    All Eligible Offerees are urged to read this Rescission Offer carefully.
 
   
    The Company has filed a registration statement on Form SB-2 with the
Securities and Exchange Commission in connection with a proposed offering of
1,500,000 units (the "Unit Offering"), each consisting of one share of the
Company's Common Stock and one warrant to purchase one share of the Company's
Common Stock. Under the terms of the underwriting agreement between the Company
and Paulson Investment Company, underwriter of the Unit Offering, the Unit
Offering is conditioned on the Company's making this Rescission Offer. The
Company does not presently intend that the registration statement filed by the
Company in connection with the Unit Offering be declared effective until the
Company has completed this Rescission Offer. There can be no assurance that the
Unit Offering will be successfully undertaken or that a public market for the
Company's Common Stock will thereafter develop, if at all, at prices equal to or
exceeding the amounts offered to offerees hereunder.
    

<PAGE>
                               TABLE OF CONTENTS
 
   

<TABLE>
<S>                                                                                     <C>
Prospectus Summary....................................................................          3
The Rescission Offer..................................................................          5
Summary Financial Data of The Company.................................................         16
Risk Factors..........................................................................         17
Dividend Policy of The Company........................................................         24
Capitalization of The Company.........................................................         24
Selected Financial Data of The Company................................................         26
Management's Discussion and Analysis of Financial Condition and Results of Operations
  of the Company......................................................................         27
Business of The Company...............................................................         28
Management of The Company.............................................................         42
Certain Transactions of The Company and AGDG..........................................         48
Principal Shareholders................................................................         50
Description of Securities of The Company..............................................         53
Shares of The Company Eligible for Future Sale........................................         56
Selected Financial Data of AGDG.......................................................         59
Management's Discussion and Analysis of Financial Condition and Results of Operations
  of AGDG.............................................................................         60
Business of AGDG......................................................................         60
Management of AGDG....................................................................         61
Description of Securities of AGDG.....................................................         62
Principal Interest Holders of AGDG....................................................         51
Legal Matters.........................................................................         62
Experts...............................................................................         63
Additional Information................................................................         63
Financial Statements..................................................................        F-1
</TABLE>

    

<PAGE>
                               PROSPECTUS SUMMARY
 
    THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY, AND SHOULD BE READ IN
CONJUNCTION WITH THE MORE DETAILED INFORMATION AND THE FINANCIAL STATEMENTS AND
NOTES THERETO APPEARING ELSEWHERE IN THIS PROSPECTUS. EXCEPT AS OTHERWISE NOTED,
ALL INFORMATION IN THIS PROSPECTUS ASSUMES (I) NO EXERCISE OF THE OVERALLOTMENT
OPTION, THE WARRANTS OR THE REPRESENTATIVE'S WARRANT IN CONNECTION WITH THE
PROPOSED OFFERING OF 1,500,000 UNITS BY THE COMPANY AND (II) A 1-FOR-3 REVERSE
SPLIT OF THE COMMON STOCK WHICH WAS COMPLETED ON NOVEMBER 4, 1996. SEE
"DESCRIPTION OF SECURITIES" AND "UNDERWRITING"
 
    THIS PROSPECTUS CONTAINS, IN ADDITION TO HISTORICAL INFORMATION,
FORWARD-LOOKING STATEMENTS THAT INVOLVE RISKS AND UNCERTAINTIES. THE COMPANY'S
ACTUAL RESULTS OR EXPERIENCE COULD DIFFER SIGNIFICANTLY FROM THOSE DISCUSSED IN
THE FORWARD-LOOKING STATEMENTS. FACTORS THAT COULD CAUSE OR CONTRIBUTE TO SUCH
DIFFERENCES INCLUDE, BUT ARE NOT LIMITED TO, THOSE DISCUSSED IN "RISK FACTORS"
AS WELL AS THOSE ELSEWHERE IN THIS PROSPECTUS.
 
                                  THE COMPANY
 
    ANTIVIRALS is a pioneer company in the field of gene-inactivating technology
referred to as antisense and has developed a patented class of antisense
compounds which may be useful in the treatment of a wide range of human
diseases. The Company also has developed new drug delivery technology which may
be useful with many FDA-approved drugs as well as with its antisense compounds.
The Company's drug development program has two areas of near-term focus:
 
    - NEU-GENE antisense compounds for selected applications, and
 
    - CYTOPORTER drug delivery engines for enhanced delivery of FDA-approved
      drugs with delivery problems.
 
    The Company's long-term product development program combines its NEU-GENE
and CYTOPORTER technologies to produce combination drugs with potential
applications for many human diseases. The Company has 20 issued patents and
several patent applications covering the basic compositions of matter, methods
of synthesis, and medical uses of NEU-GENE and CYTOPORTER compounds.
 
    Antisense technology has the potential to provide safe and effective
treatment for a broad range of diseases that previously have been difficult to
address, including viral and host diseases. The Company's new approach uses
synthetic compounds designed to inactivate selected genetic sequences that
underlie the disease process and thereby halt the disease. Targeting genetic
sequences with antisense compounds provides the selectivity that is not
available in conventional drug development which typically targets proteins
directly. The antisense approach specifically inhibits the mechanisms which
underlie the production of disease-producing proteins.
 
    To reach their therapeutic targets, many drugs must cross tissue and
cellular barriers. Drugs that have an intracellular site of action must cross
the lipid (fat-like) barrier of cellular membranes to move from the aqueous
environment in blood into the interior of target cells. Therefore, these drugs
must achieve solubility in both water and lipids. Since few compounds have these
solubility characteristics, many drug candidates are a compromise between
inherent solubility and effective delivery. This trade-off reduces efficacy and
may significantly heighten toxicity of many drug candidates, as well as many
FDA-approved drugs.
 
    The Company has developed two distinct technologies to address the critical
issues in drug development: selectivity for the target and delivery to the
target. The Company's NEU-GENE antisense technology addresses the issue of drug
selectivity and its CYTOPORTER drug delivery technology addresses delivery
problems with FDA-approved drugs and antisense compounds. The patented structure
of the Company's NEU-GENE compounds distinguishes its antisense technology from
competing technologies and provides the selectivity for a single disease target
that is the hallmark of antisense drug development. The
 
                                       3

<PAGE>
Company's molecular engine, CYTOPORTER, is designed to transport drugs with
delivery problems across the lipid barrier of cellular membranes into the
interior of cells to reach their targets.
 
    The first application of the Company's NEU-GENE antisense technology is
designed to treat restenosis, a cardiovascular disease. The Company is currently
in pre-clinical development with this compound and expects to file an IND to
begin clinical trials in 1998. The Company's first planned drug delivery
products combine its CYTOPORTER delivery engine with two FDA-approved drugs that
have delivery problems. These drugs, cyclosporin and paclitaxel
(Taxol-Registered Trademark-), will both be off patent by late 1997 and could
have much broader usage if their delivery problems are reduced. The Company
expects to file an IND to begin clinical trials with its enhanced form of
cyclosporin and to initiate pre-clinical studies with its enhanced form of
paclitaxel in 1998.
 
    The Company plans to market its initial products through marketing
agreements or other licensing arrangements with large pharmaceutical companies.
The Company intends to retain manufacturing rights to all products incorporating
its technology, whether such products are marketed directly by the Company or
through collaborative agreements with industry partners.
 
    The Company is a development stage biotechnology company which must achieve
additional significant milestones before it can commercialize either NEU-GENE
antisense compounds or its CYTOPORTER drug delivery engines. Successful
commercialization of these potential products also is dependent on the Company's
successful testing of and obtaining regulatory approval of the potential
products. This testing and regulatory approval process, if successful, will not
be completed for several years. The Company will require substantial funds to
further develop its potential products and to commercialize the products that
may be developed. There can be no assurance that the Company will achieve the
necessary milestones, successfully test its proposed products, obtain necessary
regulatory approvals, or obtain necessary financing to successfully
commercialize its proposed products.
 
    The Company's principal executive office is located at One S.W. Columbia,
Suite 1105, Portland, Oregon 97258, where the telephone number is (503)
227-0554.
 
    This Prospectus includes trademarks and registered trademarks of the
Company, including NEU-GENE-Registered Trademark- and CYTOPORTER-TM-, and
trademarks and registered trademarks of other companies.
 
                                       4

<PAGE>
                              THE RESCISSION OFFER
 
BACKGROUND
 
    For most of its existence, the Company has operated with limited capital,
most of which has been raised through periodic offerings of equity securities.
During 1992, the Company's management conducted a review of its past operations,
including capital-raising activities. At that time, although management did not
identify any specific, material failures to comply with obligations imposed on
the Company by applicable federal and state securities laws, management
concluded that the record with respect to such activities was sufficiently
incomplete that a conclusion could not be drawn with substantial certainty that
such obligations were complied with in all material respects.
 
    The Company believes that, as of the date of this prospectus, its potential
rescission liability to shareholders for failure to comply with these
obligations has been effectively eliminated by the running of applicable
statutes of limitations. The capital raising activities which were the subject
of this review were undertaken between May 1991 and October 1992. The Company's
management was unable to conclude that, with respect to certain sales during
this period, its records were sufficiently complete to demonstrate the
availability of an exemption from registration in various jurisdictions,
including Oregon, California, Colorado, District of Columbia, Florida, Illinois,
Missouri, Nevada, New York, Texas, and Washington. Except for Nevada, which
maintains a five-year statute of limitations, the applicable statutes of
limitations in these jurisdictions for a claim arising from the sale of an
unregistered security are variously two and three years. The Company accordingly
believes that any such claims are time-barred.
 
   
    Although the Company believes that such claims have been effectively
eliminated by the running of applicable statutes of limitation, a review of the
Company's securities offering documents prepared in connection with sales of
Common Stock by the Company from October 1990 to March 1994 indicated that the
Company had omitted to specifically disclose or quantify in such disclosure, or
provided only limited disclosure with respect to its then potential rescission
liablity to prospective purchasers of its Common Stock. Because this then
potential rescission liability may have been deemed material to their investment
decision by purchasers of its Common Stock, as a result of this omission or
limited disclosure, the Company's management has been unable to conclude that
sales of the Company's Common Stock made in accordance with those offering
documents complied in all material respects with the securities laws. Management
accordingly has determined that the Company would offer rescission to certain
purchasers of its Common Stock, as soon as practicable.
    
 
    The following table summarizes the shares that are the result of this
investment activity and which are the subject of this Rescission Offering,
adjusted to give effect to a 1-for-3 reverse split of the Company's Common Stock
which was completed on November 4, 1996.
 
                                       5

<PAGE>
                   SALES SUBJECT TO PAYMENT OF CASH OR NOTES
 

<TABLE>
<CAPTION>
                          DATES OF                                         NUMBER       PER SHARE
        STATE            INVESTMENT          TYPE OF TRANSACTION          OF SHARES    PRICE RANGE       TOTAL
- ----------------------  ------------  ---------------------------------  -----------  --------------  ------------
<S>                     <C>           <C>                                <C>          <C>             <C>
Alabama                     11/29/91         Investment in Common Stock       1,100   $         4.56  $      5,000
Colorado                    08/06/92         Investment in Common Stock       1,667             4.56         7,600
Illinois                 02/13/92 to         Investment in Common Stock      23,030             4.56       105,000
                            06/02/92
Massachusetts            04/10/92 to         Investment in Common Stock      17,302     4.56 to 4.95        84,750
                            01/07/94
Oregon                   10/31/90 to         Investment in Common Stock     550,648     4.56 to 4.95     2,667,013
                            03/12/94
Texas                       08/10/92         Investment in Common Stock       4,606             4.56        21,000
Washington               04/03/92 to         Investment in Common Stock      48,749     4.56 to 4.95       230,082
                            02/18/94
New Jersey                  08/11/92         Investment in Common Stock         334             4.56         1,520
                        ------------  ---------------------------------  -----------  --------------  ------------
TOTAL                                                                       667,436                   $  3,121,965
                                                                         -----------                  ------------
                                                                         -----------                  ------------
</TABLE>

 
         SHARES SUBJECT TO RETURN OF ANTI-GENE DEVELOPMENT GROUP UNITS
 

<TABLE>
<CAPTION>
                           DATES OF                                                   TOTAL     EXCHANGE      NUMBER
         STATE            INVESTMENT               TYPE OF TRANSACTION               SHARES       RATE       OF UNITS
- ------------------------  -----------  -------------------------------------------  ---------  -----------  -----------
<S>                       <C>          <C>                                          <C>        <C>          <C>
Alabama                     04/29/93   Exchange of Limited Partnership Units            4,400      1:1100         4.00
Montana                     04/29/93   Exchange of Limited Partnership Units            1,100      1:1100         1.00
Ohio                        04/29/93   Exchange of Limited Partnership Units           44,000      1:1100        40.00
Oregon                      04/29/93   Exchange of Limited Partnership Units          519,937      1:1100       472.67
Texas                       04/29/93   Exchange of Limited Partnership Units            3,300      1:1100         3.00
Utah                        04/29/93   Exchange of Limited Partnership Units            5,500      1:1100         5.00
Washington                  04/29/93   Exchange of Limited Partnership Unit            36,300      1:1100        33.00
Wisconsin                   04/29/93   Exchange of Limited Partnership Units           11,000      1:1100        10.00
                          -----------  -------------------------------------------  ---------  -----------  -----------
TOTAL                                                                                 625,537                   568.67
                                                                                    ---------               -----------
                                                                                    ---------               -----------
</TABLE>

 
    The above tables reflect investments made by persons or entities who are
currently residents of the states of Alabama, Colorado, Illinois, Massachusetts,
Montana, New Jersey, Ohio, Oregon, Texas, Utah, Washington and Wisconsin. In
addition, although the laws of the state of Florida permit the making of a
Rescission Offer in connection with registration violations, the making of a
rescission offer to residents of that state to cure a disclosure violation may
not preclude a subsequent rescission action by such Offerees. The Rescission
Offering accordingly is not being made to residents of Florida at this time and
the potential rescission liability to those investors, related to the 22,021
shares held by them, could be as much as $100,000 and one unit of limited
partnership interest in the Anti-Gene Development Group, exclusive of interest.
 
    The Company recently has achieved certain milestones in the development of
its antisense and drug delivery technologies, including improvements in the
manufacturing of its therapeutic products, preclinical studies with its
antisense agents, clinical efficacy of its antisense technology in animal
models, and filing of a patent application for its drug delivery technology. On
January 28, 1997, the Company filed a registration statement with the Securities
and Exchange Commission in connection with a proposed offering of 1,500,000
units, each consisting of one share of the Company's Common Stock and one
warrant to purchase one share of the Company's Common Stock (the "Unit
Offering"). The Company anticipates that the proceeds of the Unit Offering will
be utilized to fund pre-clinical and clinical trial studies,
 
                                       6

<PAGE>
   
additional research and development efforts, and for general working capital
purposes. Under the terms of the underwriting agreement between the Company and
Paulson Investment Company, Inc., underwriter of the Unit Offering, the Unit
Offering is conditioned on the Company's conducting this Rescission Offering.
The Unit Offering is proposed to be underwritten on a "firm commitment" basis
and the obligation of the underwriter accordingly is not conditioned on the
results of the Rescission Offer. The underwriter has informed the Company that
the underwriter intends to proceed with the proposed Unit Offering regardless of
the results of the rescission offering. Significant participation in the
rescission offering, however, could adversely affect the price at which the
underwriter will sell the Units in the Unit Offering. There can be no assurance
that a public market for the Company's Common Stock will thereafter develop, at
prices equal to or exceeding the amounts offered to offerees hereunder.
    
 
PURPOSE OF RESCISSION OFFER
 
    The securities that are the subject of the Rescission Offer include 667,436
shares of Common Stock at prices ranging from $4.56 per share to $4.95 per
share, and 625,537 shares of Common Stock obtained upon the exchange of 568.67
units of limited partnership interest in the Anti-Gene Development Group
("AGDG"). Sales of the Subject Securities were conducted under offering
documents which omitted to disclose or provided only limited disclosure that the
Company's management was unable to conclude that the Company had complied in all
material respects with its obligations under federal and state securities laws
in connection with certain prior sales of securities, with the result that the
Company may be deemed to have violated the requirements of the Securities Laws
with respect to the offer and sale of the Subject Securities.
 
    In order to limit, so far as may be permissible under the Securities Laws,
the liability of the Company with respect to the offer and sale of the Subject
Securities, the Company is unconditionally offering to repurchase all of the
Subject Securities from Eligible Offerees for an amount equal to the purchase
price of such securities plus interest from the date of purchase at the
Statutory Rate, for the return of the units of limited partnership interest in
the Anti-Gene Development Group exchanged for the Subject Securities plus
interest from the date of the exchange at the Statutory Rate, or, if the Common
Stock has been disposed of at a loss, for an amount equal to the difference
between the purchase price of such Common Stock and the price received upon
disposition plus interest at the Statutory Rate from the date of disposition
(the "Rescission Price"). The Securities and Exchange Commission takes the
position that liabilities under the federal securities laws are not terminated
by making a Rescission Offer. Subject to the closing of the Unit Offering on
terms and conditions acceptable to the Company, the Rescission Price will be
payable promptly after April 10, 1997 (the "Expiration Date"). See "Payment of
the Rescission Price."
 
                                       7

<PAGE>
    The following table sets forth the Statutory Rate of interest applicable
under state laws:
 
                               STATUTORY INTEREST
 

<TABLE>
<CAPTION>
                  RATE OF INTEREST
     STATE            PER ANNUM                            STATUTORY BASIS
- ----------------  -----------------  -----------------------------------------------------------
<S>               <C>                <C>
Alabama                      6%      Ala. Code Section 8-8-10
Colorado                     8%      Colo. Rev. Stat. Section 5-12-101
Illinois                    10%      Ill. Rev. Stat. Section 13[5/13]C.
Massachusetts                6%      Mass. Gen. Laws Ann. Ch. 110A, Section 410(e)
Montana                     10%      Mont. Code. Ann. Section 30-10-307
New Jersey                  12%      N.J. Rev. Stat. Section 49:3-71(e)
Ohio                        10%      Ohio Rev. Code Ann. Section 1343.03
Oregon                       9%      Or. Rev. Stat. Section 82.010
Texas                        6%      Tex. Code. Ann. Section 5069-1.03
Utah                        12%      Utah Code Ann. Section 15-1-1
Washington                   8%      Wash. Rev. Code Section 21.20.430(4)(b)
Wisconsin                    5%      Wisc. Stat. Section 138.04
</TABLE>

 
EFFECT OF ACCEPTANCE OF RESCISSION OFFER
 
   
    The Company believes that its potential liability under applicable state
securities laws for the sale or exchange of securities with inadequate
disclosure will be eliminated with respect to each Eligible Offeree who accepts
the Rescission Offer and sells the Subject Securities back to the Company.
However, the fact that the Company will issue promissory notes in lieu of cash
to rescinding shareholders if the aggregate Rescission Price exceeds $1,500,000
may limit the preclusive effect of the Rescission Offer in Oregon and Colorado.
The fact that the Company will provide to certain rescinding shareholders units
of limited partnership interest in AGDG in lieu of cash may limit the preclusive
effect of the Rescission Offer in Alabama, Montana, Ohio, Oregon, Texas, Utah,
Washington, and Wisconsin. Moreover, the Securities and Exchange Commission
takes the position that liabilities under the federal securities laws are not
terminated by making a rescission offer.
    
 
    This Prospectus constitutes notice, as required by Oregon Revised Statutes
("ORS") 59.125, of the Company's offer to pay the Rescission Price upon tender
of the Common Stock subject to this Rescission Offer ("Notice"). Pursuant to ORS
59.125, an offeree may not commence an action under ORS 59.115 (which provides
for liability in connection with sales of securities in violation of the Oregon
Securities Laws or by means of a material misstatement or omission) with respect
to his or her purchase of the Common Stock subject to this Rescission Offer
after receipt of this Notice unless (i) if the Eligible Offeree owns such Common
Stock when this Prospectus is received, he or she accepted the Rescission Offer
prior to the Expiration Date and has not been paid the full amount due
thereunder, or (ii) if the Eligible Offeree does not own such Common Stock when
this Prospectus is received, he or she so notifies the Company in writing within
30 days of such receipt. A failure of any Eligible Offeree to respond to this
Notice within the prescribed period of time will have the effect of precluding
such Eligible Offeree from commencing an action under ORS 59.115. States other
than Oregon, including Alabama, Colorado, Illinois, Massachusetts, Montana, New
Jersey, Ohio, Texas, Utah, Washington and Wisconsin, have similar laws regarding
the effect of a decision not to accept the Rescission Offer.
 
    ORS 59.125 and Colo. Rev. Stat. 11-51-604(9)(a)(i) do not expressly permit
the issuance of promissory notes in lieu of cash in a rescission offering.
Although no Oregon court has addressed this issue in a reported decision, a
Colorado appellate court, construing the Colorado Statute, has ruled that a
party accepting a promissory note in lieu of cash in a rescission offering may
not commence an action for violation of securities laws relating to the original
sale. Although it has not expressed an opinion on this
 
                                       8

<PAGE>
issue, the Oregon Division of Finance and Corporate Securities has previously
permitted a party in a rescission offering of promissory notes in lieu of cash
to maintain that the sole remedy of a party who accepted the offer was to bring
suit on the notes and that any other remedies the investor might have had under
the Oregon Securities Laws were extinguished by the rescission offering.
Although the Company believes that the Rescission Offering will have preclusive
effect if all of the Oregon and Colorado holders of 1,072,252 shares of the
Company's Common Stock were to successfully assert claims against the Company,
the Company would be required to pay those holders approximately $2,674,613,
plus approximately 473 units of limited partnership in AGDG, plus statutory
interest.
 
   
    Although the state rescission statues generally require the Company to
tender to eligible shareholders the consideration paid by such shareholders for
the Company's Common Stock, the fact that the Company will provide to certain
rescinding shareholders units of limited partnership interest in AGDG in lieu of
cash may limit the preclusive effect of the Rescission Offer in Alabama,
Montana, Ohio, Oregon, Texas, Utah, Washington, and Wisconsin. Although the
Company believes that the Rescission Offer will have preclusive effect, if all
of the holders of the 625,537 shares of the Company's Common Stock offered the
limited partnership interest in AGDG successfully asserted claims against the
Company, the Company could be required to pay these holders approximately
$2,852,449. Even if the Company were successful in defending any securities law
claims, the assertion of such claims against the Company additionally would
result in costly litigation and significant diversions of effort by the
Company's management.
    
 
    To the extent that Eligible Offerees affirmatively reject or fail to respond
to the Company's Rescission Offer, potential liability of the Company under the
1933 Act may not be completely extinguished. Nevertheless, under those
circumstances, the Company will assert that an Eligible Offeree who
affirmatively rejects or fails to respond to the Company's Rescission Offer has
released his claims to recover the purchase price of the securities and that
such claims further are barred by applicable statutes of limitation. The
Securities and Exchange Commission takes the position that liabilities under the
federal securities laws are not terminated by making a rescission offer. If the
affirmative rejection or failure to respond to the Rescission Offer does not act
as a release of claims, each Eligible Offeree who affirmatively rejects or fails
to respond to the Rescission Offer would retain any rights or claims such
Eligible Offeree may have under the federal securities laws, subject to the
statute of limitations with respect to such rights and claims. In general, for a
claim based on violations of the registration provisions of the federal
securities laws, such a claim must be brought within one year after discovery of
the violation upon which the claim is based, provided that, in no event may such
claims be brought more than three years after the occurrence of the violation.
The Company accordingly believes that the applicable statute of limitations has
run with respect to such claims. In addition, the Rescission Offer will not
prevent the Securities and Exchange Commission from pursuing enforcement action
against the Company with respect to any violations of the federal securities
laws that may have occurred.
 
    A decision to reject the Rescission Offer will not affect the restricted
status of the Common Stock held by the Eligible Offerees. See "Description of
Securities--Restrictions on Transfer."
 
                   PROVISION OF UNITS OF LIMITED PARTNERSHIP
                    INTEREST IN ANTI-GENE DEVELOPMENT GROUP
 
    The Company will return to certain purchasers of the Company's Common Stock,
if they accept the Rescission Offer, units of limited partnership interest in
AGDG exchanged for the Company's Common Stock on or about April 29, 1993.
 
    AGDG was formed in 1981 under the Oregon Uniform Limited Partnership Act for
the purpose of funding the development of and obtaining the proprietary rights
to Anti-Genes. Prior to 1993, AGDG periodically contracted with the Company to
develop the technologies while retaining the rights to the resultant
technologies. Substantially all of the proceeds from sales of interests in AGDG
and interest income were paid to the Company under the terms of these research
and development contracts.
 
                                       9

<PAGE>
    Sole management of AGDG is vested in the general partner. The general
partner of AGDG is Dr. James Summerton, founder and Chairman and Chief Executive
Officer of the Company until January 1996. Dr. Summerton presently serves as
President and Chief Scientific Officer of the Company. Dr. Summerton receives no
fees or other remuneration for his management of AGDG.
 
    In February 1993, to facilitate additional capital raising activities
associated with the development of the technologies, AGDG and the Company
entered into a Technology Transfer Agreement whereby, effective May 19, 1993,
AGDG conveyed all intellectual property in its control to the Company. In
consideration of this transfer, the Company is obligated to pay to AGDG certain
technology transfer fees arising from the sale of products incorporating the
technologies. See "Effect of Rescission Offering on the Anti-Gene Development
Group and Technology Transfer Agreement."
 
    During March, 1993, the Company offered all holders of interests in AGDG the
opportunity to exchange their units of limited partnership interest for shares
of the Common Stock of the Company at a ratio of 1,100 shares of Common Stock
for each unit exchanged. The exchange ratio was determined based on historical
perceptions by the partners of AGDG and shareholders of the Company as to the
relative values of AGDG, but was not confirmed by financial analysis of any
kind. The exchange offer was the subject of a fairness hearing conducted by the
Oregon Department of Insurance and Finance on April 19, 1993, and after such
hearing the Oregon Department of Insurance and Finance issued an order
permitting the exchange offering to proceed.
 
    Prior to the exchange offering, there were 3665.5 units of limited
partnership interest in AGDG outstanding. Holders of 1,809.5 units exchanged
those units for shares of Common Stock of the Company in the offer. As of the
date of this Prospectus, 1856 units of limited partnership interest in AGDG are
outstanding. If all Eligible Offerees who participated in the exchange offer
tender their 625,537 shares and 568.67 units of limited partnership interest are
issued therefor, 2424.67 units of limited partnership interest will be
outstanding.
 
    The Company and AGDG believe that the rights of an interest holder in AGDG
upon completion of this Rescission Offering are equivalent to the rights of an
interest holder immediately prior to the 1993 exchange offering. In addition to
cash and cash equivalents of approximately $189,000 as of December 31, 1996,
AGDG's principal asset, as it was prior to the exchange offering, is the right
to technology transfer payments arising from the sale of products incorporating
the transferred technologies. The units of limited partnership interest in AGDG
are speculative investments and unit holders bear the risk of the loss of their
entire investment. In addition, the investment in units of limited partnership
interest in AGDG is subject to additional risks, including the lack of a public
market for the interests, uncertainty of the utility and commercial viability of
the technologies, uncertainty of the superiority of the technologies, and
uncertainty in the obtaining of adequate financing to achieve effective
commercialization of products arising from the technologies. AGDG's achievement
of revenues based on the technology transfer fees is based on the successful
commercialization of the technologies by the Company. For a detailed statement
of the risks associated with the Company, see "Risk Factors."
 
        EFFECT OF RESCISSION OFFERING ON THE ANTI-GENE DEVELOPMENT GROUP
                       AND TECHNOLOGY TRANSFER AGREEMENT
 
    The Company will return to certain purchasers of the Company's Common Stock,
if they accept the Rescission Offer, units of limited partnership interest in
the Anti-Gene Development Group exchanged for the Company's Common Stock on or
about April 29, 1993.
 
    On February 9, 1993, the Company and AGDG entered into a Technology Transfer
Agreement wherein effective May 19, 1993, AGDG conveyed all intellectual
property in its control related to antisense technology (the "Intellectual
Property") to the Company. As part of the conveyance, the Company tendered to
AGDG for liquidation all partnership units received pursuant to an exchange
offer and received a 49.37 percent undivided interest in the intellectual
property. The Company then purchased the
 
                                       10

<PAGE>
   
remaining undivided interest in the Intellectual Property in consideration of
payments of 4.05% of gross revenues in excess of $200 million, if any, derived
from sales of products which would, in the absence of the Technology Transfer
Agreement, infringe a valid claim under any patent transferred to the Company
(the "Technology Fees"). The level of this Technology Fee was fixed based on the
level of participation of AGDG interestholders in the 1993 exchange offering.
Under that offer, if all 3665.5 units of the limited partnership then
outstanding were exchanged, the Technology Fee would be 0%. If no interests were
exchanged, the fee would be 8%. The fee was reduced on a pro rata basis for each
unit exchanged. See "Comparison of Units of Limited Partnership Interest in the
Anti-Gene Development Group before the 1993 Exchange Offer and Units of Limited
Partnership Interest Offered Hereby." The Company's obligation to make payments
of the Technology Fees with respect to a particular product terminates upon the
expiration of all patents transferred to the Company pursuant to the Technology
Transfer Agreement related to that product.
    
 
    Pursuant to a License and Option Agreement by and between AGDG and the
Company dated February 9, 1993 (the "License Agreement"), the Company granted to
AGDG a royalty-free non-exclusive license to use the Intellectual Property for
internal research and development and to sell small quantities of products
incorporating the Intellectual Property. In addition, if AGDG develops any
specific prototype products which incorporate any of the Intellectual Property,
the Company has the right to commercialize and market such products in
consideration of payments of 4.05% of gross revenues, in excess of the $200
million exemption for all products utilizing the Intellectual Property, to AGDG.
If the Company elects not to commercialize the proposed AGDG product or fails to
meet certain product development milestones, the Company is required to grant
AGDG a license to develop and market the proposed product (an "AGDG License").
The Company is entitled to payments for the AGDG license but only if the
proposed product incorporates patented improvements developed by the Company to
the Intellectual Property. The amount of the license fee payable to the Company
by AGDG pursuant to an AGDG License, if any, is equal to the percentage payable
to AGDG for products sold by the Company and covered by the Technology Transfer
Agreement. AGDG also has the right to obtain an exclusive royalty-free license
to use, develop, make, sell, distribute and sublicense products utilizing the
Intellectual Property at such time as the Company has less than 10 full-time
employees engaged in developing, testing or marketing products based upon the
Intellectual Property for a period of at least 180 consecutive days.
 
   
    AGDG's entitlement to Technology Fees constitutes a material asset of AGDG.
The payment of such fees is dependent upon the successful commercialization of
products incorporating the Intellectual Property by the Company, which is
dependent in part on the Company's ability to raise capital on terms and
conditions acceptable to the Company. To facilitate the making of the Rescission
Offer, which is a condition to the underwriting of the Company's proposed Unit
Offering, AGDG has agreed to issue units of limited partnership interest to
certain shareholders of the Company who accept the Rescission Offer in
consideration of the Company's agreement to increase the Technology Fees and
License Agreement fees. This increase will be determined by the formula
originally negotiated by the Company and AGDG in connection with the 1993
exchange offer and technology transfer. The amount of any increase will depend
on the number of units of limited partnership interest that Anti-Gene
Development Group is required to issue in connection with the Rescission Offer.
If all 625,537 shares are tendered for rescission and 568.67 units of limited
partnership interest are required to be issued in payment therefor, the
Technology Fees and License Agreement fees would increase to 5.27% of sales in
excess of the $200 million exemption. If no shares are tendered for rescission
and no units of limited partnership interest are required to be tendered
therefor, the Technology Fees and License Agreement fees will remain 4.05%. See
"Comparision of Units of Limited Partnership Interest in Anti-Gene Development
Group before the 1993 Exchange Offer and Units of Limited Partnership Interest
Offered Hereby."
    
 
   
    On January 20, 1997, AGDG and the Company amended the Technology Transfer
Agreement to reduce the Technology Fees arising from the sale of diagnostic
products from 4.05% to 2% and to remove the $200 million exemption with respect
to sales of such diagnostic products. For purposes of the
    
 
                                       11

<PAGE>
   
amendment, a diagnostic product is defined to include any product which is
approved for detecting or quantitating outside any animal body one or more
selective nucleic acid sequences. A therapeutic product is defined to include
any product which is approved for use in or is used in a human or other animal
to achieve a therapeutic or prophylactic effect. AGDG and the Company believe
that such an adjustment was necessary in connection with potential diagnostic
applications of the Intellectual Property because negotiated license fees or
royalties in connection with diagnostic products typically are lower than those
for therapeutic products and the prior rate exceeded the levels that would
permit the licensing of the technologies to third parties on favorable terms and
conditions. The Company also granted to AGDG a royalty-bearing license to make,
use and sell small quantities of product derived from the Intellectual Property
for research purposes only. The Technology Fees arising from the sale of
diagnostic products will not be adjusted if the Anti-Gene Development Group
issues units of limited partnership interest in connection with the Rescission
Offer. Based on the amendment, the Technology Fee for therapeutic products
remains 4.05% of gross revenues of sales in excess of $200 million and the fee
for diagnostic products is 2% of gross revenues of sales with no sales
exemption.
    
 
   
    The original Technology Fee and the 2% Technology Fee for diagnostic
products were determined by negotiation between Dr. Burger, on behalf of the
Company, and Dr. Summerton, on behalf of AGDG, subject to approval of the
negotiated amounts by the Board of Directors of the Company. The fees negotiated
reflect fees deemed appropriate by the parties based on fee structures proposed
by potential strategic partners of the Company and AGDG. The Company's Board of
Directors recognized that Dr. Summerton had a direct conflict of interest in
these negotiations and required that the original agreement and amendment be
approved by a majority of disinterested directors after disclosure of the
conflict.
    
 
   
COMPARISON OF UNITS OF LIMITED PARTNERSHIP INTEREST IN THE ANTI-GENE DEVELOPMENT
  GROUP BEFORE THE 1993 EXCHANGE OFFER AND UNITS OF LIMITED PARTNERSHIP INTEREST
  OFFERED HEREBY
    
 
   
    The share of profits and losses to which each partner is entitled is
established by the Anti-Gene Development Group Certificate of Limited
Partnership. See "Description of the Securities of AGDG." Profits, if any, are
distributed pro rata to all partnership interests.
    
 
   
    Prior to the 1993 exchange offering, there were 3665.5 units of limited
partnership interest of AGDG outstanding. Pursuant to the Technology Transfer
Agreement between the Company and AGDG, entered prior to the exchange offer, in
addition to cash of approximately $190,000, the principal asset of AGDG was the
right to receive Technology Fees arising from the sale of therapeutic or
diagnostic products incorporating the technologies transferred by AGDG to the
Company. The amount of these payments, a percentage of the gross revenues from
sales in excess of $200 million, was to be fixed by the level of participation
by AGDG interest holders in the 1993 exchange offering. If all 3665.5 units were
exchanged and no units of limited partnership interest in AGDG remained
outstanding, the Technology Fee would be 0%. If no interests were exchanged, the
fee would be 8%. Immediately prior to the exchange offering, each holder of a
unit of limited partnership interest in AGDG enjoyed a 1/3666 interest in any
profits derived from a Technology Fee of 8% of gross revenues from therapeutic
or diagnostic sales in excess of $200 million or approximately .002% of such
gross revenues per unit. The fee was subject to ratable reduction from 8% to 0%,
depending on the number of limited partnership interests exchanged. Because
holders exchanged 1809.5 units of limited partnership interest in AGDG in the
1993 offer, 1856 units were outstanding after the offer and the Technology Fee
was reduced to 4.05%. Interest holders' entitlement to profits remained
unchanged, at approximately .002%, because the reduction in the Transfer Fee
corresponded to the reduction in outstanding units of limited partnership
interest.
    
 
   
    In January 1997, the Technology Transfer Agreement was amended to reduce the
Transfer Fees payable from sales of diagnostic products from 4.05% to 2% and to
remove the $200 million exemption. This amendment was requested by AGDG based on
the determination, subsequent to the negotiation of the Technology Transfer
Agreement, that the payment of Technology Fees of 4.05% might render
    
 
                                       12

<PAGE>
   
commercialization of the technologies for diagnostic use unprofitable due the
lower royalties paid for diagnostic products.
    
 
   
    As of the date of this Prospectus, the principal asset of AGDG, in addition
to cash of approximately $189,000, remains the right to receive the Technology
Fees. If all Eligible Offerees who participated in the exchange offer tender
their 625,537 shares and 568.67 units of limited partnership interest are issued
therefor, 2424.67 units of limited partnership interest will be outstanding. The
Technology Fees would increase to 5.27% of gross revenues arising from sales of
therapeutic products in excess of the $200 million exemption but would remain at
2% with respect to sales of diagnostic products. The pro rata share of profits
derived from therapeutic sales enjoyed by a rescinding Eligible Offeree, 1.2425
of 5.27% or approximately .002%, would be equal to that of an interest holder
both immediately prior to and after the 1993 exchange offer. Although the pro
rata share of profits derived from therapeutic product sales would be reduced to
1/2425 of 2% or .001%, this reduction is accompanied by the elimination of the
$200 million sales exemption.
    
 
   
    No Technology Fees have been paid by the Company to AGDG and there can be no
assurance that Company will successfully commercialize the technologies. For a
detailed statement of the risks associated with the Company, see "Risk Factors."
    
 
CERTAIN TAX CONSIDERATIONS RELATING TO THE RESCISSION OFFER
 
    An Eligible Offeree's acceptance of the Rescission Offer and receipt of the
payment thereunder will be a taxable event for both state and federal income tax
purposes. However, if the amount received by the Eligible Offeree as a result of
the acceptance of the Rescission Offer does not exceed the tax basis for the
securities surrendered, there will be no realized taxable gain. Amounts received
as interest in connection with the Rescission Offer will be taxable to the
recipient at ordinary income tax rates.
 
    BECAUSE OF UNCERTAINTIES RELATING TO THE FEDERAL, STATE AND LOCAL INCOME TAX
TREATMENT OF ACCEPTANCE OF THE OFFER OF RESCISSION, ELIGIBLE OFFEREES WHO MAY
WISH TO ACCEPT THE RESCISSION OFFER ARE URGED TO CONSULT THEIR PERSONAL TAX
ADVISORS BEFORE ACCEPTING OR REJECTING THE RESCISSION OFFER.
 
PROCEDURES FOR TENDERING SECURITIES
 
    For an Eligible Offeree to validly tender securities pursuant to the
Rescission Offer, a properly completed Request for Rescission in the form
attached hereto, evidencing the decision of the Eligible Offeree to accept the
Rescission Offer, must be received by the Company at its principal executive
offices (One S.W. Columbia, Suite 1105, Portland, Oregon 97258) on or before
5:00 p.m., Portland, Oregon time, on or before April 10, 1997, the Expiration
Date. Documentation received by the Company other than at the address specified
above or after 5:00 p.m. on the Expiration Date, incomplete or invalid
documentation, or documentation purporting to accept the Rescission Offer in a
manner not permitted by the terms of the Rescission Offer will not be deemed to
constitute acceptance of the Rescission Offer. Pursuant to ORS 59.125, an
Eligible Offeree must accept the payment offer within 30 days of receipt of the
rescission notice. States other than Oregon, including Alabama, Colorado,
Illinois, Massachusetts, Montana, New Jersey, Ohio, Texas, Utah, Washington and
Wisconsin, have similar laws permitting the offeree not more than 30 days after
receipt of a rescission offer within which to accept the offer.
 
    The Request for Rescission must be accompanied by Common Stock certificates
representing all (and not less than all) of the Subject Securities purchased by
the Eligible Offeree in any particular transaction. If an Eligible Offeree
purchased Subject Securities from the Company in more than one transaction, such
Eligible Offeree may accept the Rescission Offer with respect to the securities
purchased in one transaction and reject the Rescission Offer with respect to
securities purchased in other transactions. The Rescission Offer does not apply
to any securities of the Company other than the Subject Securities.
 
                                       13

<PAGE>
   
    The Request for Rescission and stock certificates may be delivered by hand
or courier service, or by mail. Each stock certificate must be duly endorsed in
blank by the registered holder thereof and the signature should be guaranteed by
an eligible guarantor institution (banks, stockbrokers, savings and loan
associations, and credit unions with membership in an approved signature
guarantee medallion program). The Company's stock transfer agent, ChaseMellon
Shareholder Services, has advised the Company that, as a security device for the
protection of shareholders and the Company, securities tendered for cancellation
should include signatures with respect to which a guarantee has been obtained.
This is a common requirement of ChaseMellon Shareholder Services. The method of
delivery of all documents is at the election and risk of the Eligible Offeree.
If delivery is by mail, registered mail, return receipt requested, properly
insured, is recommended. The Company will seek to notify Eligible Offerees who
submit incomplete or invalid Requests for Rescission to the Company by mailing
notice of the same to the Eligible Offeree's last known address prior to deeming
the Rescission Offer rejected by the Eligible Offeree.
    
 
    Tenders of shares made pursuant to the Rescission Offer may be withdrawn by
written notice to the Company at any time prior to the Expiration Date.
 
PAYMENT OF THE RESCISSION PRICE
 
    At the Expiration Date, the Company will become obligated to pay the
Rescission Price to each Eligible Offeree who has properly tendered shares
pursuant to the Rescission Offer and has not withdrawn such tender prior to the
Expiration Date. Each such Eligible Offeree will cease to be a shareholder of
the Company with respect to the tendered shares upon payment by the Company of
the Rescission Price. Payment for any shares of Common Stock validly tendered
and not withdrawn will be made promptly after the Expiration Date.
 
    The Company has reserved up to $1,500,000 in cash to cover liabilities under
this Rescission Offering. To the extent that shares with an aggregate cash
Rescission Price in excess of $1,500,000 are tendered to the Company pursuant to
the Rescission Offer, the Company will issue to rescinding shareholders in the
states of Oregon and Colorado a portion of the Rescission Price in the form of
promissory notes of the Company bearing interest at a rate of 9% per annum and
with maturities ranging from 18 months to 36 months (the "Notes"). Shareholders
who reside in Oregon and Colorado may receive Notes because there is
administrative or judicial precedent in those jurisdictions for the issuance of
promissory notes in connection with a rescission offering. The first $1.5
million of rescission liabilities will be paid in cash; the next $1 million will
be paid in Notes with a term of 18 months, bearing interest at 9% per annum; the
next $1 million will be paid in Notes with a term of 24 months, bearing interest
at 9% per annum; the next $1 million will be paid in Notes with a term of 30
months, bearing interest at 9% per annum; the balance of rescission liabilities
will be paid in Notes having a term of 36 months, bearing interest at 9% per
annum. Priority with respect to the payment of cash will be given to rescinding
shareholders who resided in states other than Oregon and Colorado at the time
they purchased or otherwise obtained their shares, to the extent of their cash
investment in such shares and statutory interest thereon and, in the case of
former holders of units of interest in AGDG who resided in states other than
Oregon and Colorado, to the extent of their statutory interest thereon. After
the payments to such shareholders, the remainder of the rescission liabilities
will be paid to shareholders who resided in Oregon and Colorado on a pro rata
basis. Accordingly, for example, if the aggregate rescission price exceeds $3
million, each rescinding shareholder who resided in states other than Oregon and
Colorado at the time they purchased or otherwise obtained their shares will
receive their Rescission Price in cash, or units of interest in AGDG, as
applicable, and cash payment of statutory interest thereon, and each other
rescinding shareholder will receive its pro rata share of cash, 18-month Notes,
24-month Notes, and units, as applicable. Interest on the Notes will be paid
quarterly and all principal will be due at the end of the term of the Note.
 
    Payment by the Company of its obligations under the Notes will be secured by
a pledge of shares of the Common Stock of the Company held of record by certain
of the Company's directors, officers and principal shareholders (the
"Pledgors"), including Dr. Denis R. Burger, Dr. James E. Summerton,
 
                                       14

<PAGE>
Dr. Dwight D. Weller, Nick Bunick, Dr. Donald R. Johnson, Dr. James E. Reinmuth
and Cascadia Pacific Management, LLC for the benefit of the Oregon Resource
Technology and Development Fund. The Pledgors have agreed to pledge the shares
of Common Stock to facilitate the making of the Rescission Offer. As of the date
of this Prospectus, the Pledgors hold of record 3,569,030 shares of the Common
Stock of the Company, which shares may be pledged to secure payment of the
Notes.
 
    Under the terms of the Pledge Agreement, prior to the closing of the
Company's proposed offering of 1,500,000 units, the Pledgors have agreed to
maintain as security for payment of the Notes sufficient shares of Common Stock
of the Company that the aggregate value of such shares, based on an estimated
value of $6.00 per share, equals 120 percent of the outstanding principal amount
of the Notes. After the closing of the proposed unit offering or any other
public offering, the Pledgors have agreed to maintain as security for payment of
the Notes sufficient shares of Common Stock of the Company that the aggregate
value of such shares, based on the last reported sales price of the Company's
Common Stock on the last day of the preceding month, equals 120 percent of the
outstanding principal amount of the Notes. The Pledge Agreement provides that,
in the event of a default by the Company in the payment of the Notes, shares of
the Company's Common Stock subject to the pledge will be sold and the proceeds
applied to payment of obligations. To facilitate the sale of the shares in the
event of a default in the payment of the Notes, the shares have been registered
for sale with the Securities and Exchange Commission.
 
   
    If all Eligible Offerees tender their shares, the Company will be required
to issue Notes with a principal amount of approximately $3,750,965. The Pledgors
have agreed to contribute shares on a share-for-share basis until a sufficient
number of shares has been pledged. The number of shares required to be pledged
if Notes in the approximate principal amount of $3,750,965 are issued and the
maximum number of shares that may be pledged by each Pledgor are 41,151 and
41,151, respectively, for Dr. Burger 169,608 and 2,394,587, respectively, for Dr
Summerton 169,608 and 249,300, respectively, for Dr. Weller, 167,400 and 167,400
respectively, for Mr. Bunick, 14,334 and 14,334, respectively, for Dr. Johnson
18,484 and 18,484, respectively, for Dr. Reinmoth, and 169,608 and 957,452,
respectively, for the Oregon Resource
Technology and Development Fund.
    
 
    The Company has been unprofitable since its inception and has received no
material revenues from the sale of products or other sources. The Company does
not anticipate material revenues in the near term. The proceeds of the Company's
proposed Unit Offering are the only source of capital potentially available in
the near term to the Company, other than its existing cash and cash equivalents.
There can be no assurance that the proposed Unit Offering will be successfully
undertaken by the Company. Even if successful, although the Company's management
enjoys broad discretion with respect to the use of proceeds from the Unit
Offering, there can be no assurance that proceeds will be applied to the payment
of the Notes or that any proceeds will be available therefor upon the maturity
of the Notes. Moreover, based on the Company's current operating plan, if the
Company experiences unanticipated cash requirements during the next 24 months,
including without limitation cash required to pay holders of a significant
number of shares of its Common Stock in connection with the rescission offering,
the Company could require significant additional capital to fund operations,
continue research and development programs, pre-clinical and clinical testing of
its potential antisense and drug delivery compounds, commercialize any products
that may be developed and make payments on the Notes. There can be no assurance
that, however, that additional funds will be available, if at all.
 
    There previously has been no public market for the Company's Common Stock
and there can be no assurance that an active public market for the Common Stock
will be developed or sustained after the Rescission Offer. In addition, even if
such a public market does develop, the obligations of the Pledgors to pledge
shares is limited to shares held of record by the Pledgors as of the date of
this Prospectus and there can be no assurance that the value of the Company's
Common Stock on such public market will be sustained at levels so that the
shares subject to the pledge will be sufficient to satisfy the obligations of
the Company in the event of a default by the Company in the payment of the
Notes. Regardless of the sufficiency of the pledged shares, the Pledgors have no
recourse liability on the Notes.
 
                                       15

<PAGE>
                     SUMMARY FINANCIAL DATA OF THE COMPANY
 

<TABLE>
<CAPTION>
                                                                               YEAR ENDED
                                                                              DECEMBER 31,
                                                                      ----------------------------
                                                                          1995           1996
                                                                      -------------  -------------   PERIOD FROM
                                                                                                    JULY 22, 1980
                                                                                                     (INCEPTION)
                                                                                                       THROUGH
                                                                                                     DECEMBER 31,
                                                                                                         1996
                                                                                                    --------------
                                                                                                     (UNAUDITED)
<S>                                                                   <C>            <C>            <C>
STATEMENTS OF OPERATIONS DATA:
Revenues, from grants and research contracts........................  $      82,500  $      27,227  $      689,497
                                                                      -------------  -------------  --------------
Operating expenses:
  Research and development..........................................      2,097,796      1,729,554       9,011,574
  General and administrative........................................        609,723        613,811       4,549,582
                                                                      -------------  -------------  --------------
        Total operating expenses....................................      2,707,519      2,343,365      13,561,156
                                                                      -------------  -------------  --------------
Other income........................................................         68,133        228,776         446,176
                                                                      -------------  -------------  --------------
Net loss............................................................  $  (2,556,886) $  (2,087,362) $  (12,425,483)
                                                                      -------------  -------------  --------------
                                                                      -------------  -------------  --------------
Net loss per share(1)...............................................  $       (0.37) $       (0.25)
                                                                      -------------  -------------
                                                                      -------------  -------------
Shares used in per share
  calculation(1)....................................................      6,982,459      8,233,548
                                                                      -------------  -------------
                                                                      -------------  -------------
</TABLE>

 

<TABLE>
<CAPTION>
                                                                        DECEMBER 31, 1996
                                                  --------------------------------------------------------------
                                     DECEMBER                      AS ADJUSTED     AS ADJUSTED     AS ADJUSTED
                                       1995           ACTUAL           (2)             (3)             (4)
                                  --------------  --------------  --------------  --------------  --------------
<S>                               <C>             <C>             <C>             <C>             <C>
BALANCE SHEET DATA
Working capital.................         646,814       2,738,677     14,346,177      12,846,177      12,846,177
Total assets....................       2,324,736       4,248,899     15,856,399      14,356,399      14,356,399
Common stock subject to
  rescission....................       3,121,965       3,121,965      3,121,965       2,229,401         --
Deficit accumulated during the
  development stage.............     (10,338,121)    (12,425,483)   (12,425,483)    (13,032,917)    (14,550,141)
Total shareholders' equity
  (deficit).....................      (1,051,293)        796,127     12,403,627      11,796,193      10,278,969
</TABLE>

 
- ------------------------
 
(1) See Note 2 of Notes to Financial Statements for an explanation of the
    determination of the number of shares used in computing net loss per share.
 
(2) Adjusted to give effect to the application of the estimated net proceeds of
    the Company's Unit Offering based upon an assumed initial public offering
    price of $9.00 per Unit. See "Use of Proceeds" and "Management's Discussion
    and Analysis of Financial Condition and Results of Operations."
 
(3) Assumes that shares with an aggregate Rescission Price of $1.5 million are
    tendered for rescission, which represents the cash portion of the Company's
    potential payments under the Rescission Offer.
 
(4) Assumes that shares with an aggregate Rescission Price of $5,246,623 are
    tendered for rescission, the first $1.5 million of which is paid in cash and
    the next $3,746,623 is paid through the issuance of the Company's one and
    one-half year to three-year 9% notes.
 
                                       16

<PAGE>
                                  RISK FACTORS
 
    THE COMMON STOCK THAT IS THE SUBJECT OF THIS RESCISSION OFFER INVOLVES A
SUBSTANTIAL DEGREE OF RISK AND SHOULD BE REGARDED AS SPECULATIVE. ELIGIBLE
OFFEREES SHOULD CAREFULLY CONSIDER, IN ADDITION TO THE MATTERS SET FORTH
ELSEWHERE IN THIS PROSPECTUS, THE FOLLOWING FACTORS RELATED TO THE BUSINESS OF
THE COMPANY AND THE RESCISSION OFFERING.
 
    POTENTIAL RESCISSION LIABILITY.  This Rescission Offering is being made to
all holders of the Subject Securities. If all of the Eligible Offerees who are
holders of the Subject Securities accept the Rescission Offer, the Company would
be required to make payments in the amount of $3,121,965, plus interest at the
Statutory Rate in the approximate amount of $2,129,000, plus applicable interest
on the Notes, plus approximately 568.67 units of limited partnership interest in
AGDG. Although the Company has limited the amount of its cash payments to
$1,500,000, the payment of any amount in cash or pursuant to the Notes will
reduce the liquidity and financial resources of the Company and may adversely
affect the future growth of the Company as well as its financial condition and
results of operations.
 
    The Company believes that its potential liability under state securities
laws for the sale or exchange of securities with inadequate disclosure will be
eliminated with respect to each Eligible Offeree who accepts the Rescission
Offer and sells the Subject Securities back to the Company. However, the fact
that the Company will issue promissory notes in lieu of cash to rescinding
shareholders residing in Oregon and Colorado if the aggregate Rescission Price
exceeds $1,500,000 may limit the preclusive effect of the Rescission Offer in
Oregon and Colorado. If all Oregon and Colorado holders of the 1,072,252 shares
successfully asserted claims against the Company, the Company would be required
to pay these holders approximately $2,674,613, plus approximately 472.67 units
of limited partnership interest in AGDG, plus statutory interest. Even if the
Company were successful in defending any securities law claims, the assertion of
such claims against the Company additionally would result in costly litigation
and significant diversions of effort by the Company's management.
 
   
    Although the state rescission statutes generally require the Company to
tender to eligible shareholders the consideration paid by such shareholders for
the Company's Common Stock, the fact that the Company will provide to certain
rescinding shareholders units of limited partnership interest in AGDG in lieu of
cash may limit the preclusive effect of the Rescission Offer in Alabama,
Montana, Ohio, Oregon, Texas, Utah, Washington, and Wisconsin. Although the
Company believes that the Rescission Offer will have preclusive effect, if all
of the holders of the 625,637 shares of the Company's Common Stock offered the
limited partnership interest in ADGD successfully asserted claims against the
Company, the Company could be required to pay these holders approximately
$2,852,449. Even if the Company were successful in defending any securities law
claims, the assertion of such claims against the Company additionally would
result in costly litigation and significant diversions of effort by the
Company's management.
    
 
    The Securities and Exchange Commission takes the position that liabilities
under the federal securities laws are not terminated by making a rescission
offer. To the extent that Eligible Offerees affirmatively reject or fail to
respond to the Company's Rescission Offer, potential liability of the Company
under the 1933 Act may not be completely extinguished. Nevertheless, under those
circumstances, the Company will assert that an Eligible Offeree who
affirmatively rejects or fails to respond to the Company's Rescission offer has
released his claims to recover the purchase price of the securities and that
such claims further are barred by applicable statutes of limitation. If the
affirmative rejection or failure to respond to the Rescission Offer does not act
as a release of claims, each Eligible Offeree who affirmatively rejects or fails
to respond to the Rescission Offer would retain any rights or claims such
Eligible Offeree may have under the federal securities laws, subject to the
statute of limitations with respect to such rights and claims. In general, for a
claim based on violations of the registration provisions of the federal
securities laws, such a claim must be brought within one year after discovery of
the violation upon which the claim is based, provided that, in no event may such
claims be brought more than three years after the occurrence of the
 
                                       17

<PAGE>
violation. The Company accordingly believes that the applicable statute of
limitations has run with respect to such claims. Notwithstanding the foregoing,
if all holders of the 1,292,973 shares subject to the Rescission Offer
successfully asserted claims against the Company, the Company would be required
to pay these holders approximately $3,121,965, plus approximately 568.67 units
of limited partnership interest in AGDG, plus statutory interest. Even if the
Company were successful in defending any securities law claims, the assertion of
such claims against the Company additionally could result in costly litigation
and diversions of effort by the Company's management. In addition, the
Rescission Offer will not prevent the Securities and Exchange Commission from
pursuing enforcement action against the Company with respect to any violations
of the federal securities laws that may have occurred.
 
    In addition, the rescission offer is not being made to holders of 22,021
shares of the Company's Common Stock who reside in Florida, the laws of which do
not permit rescission offerings to cure omissions in securities offering
documents. These holders of 22,021 shares of Common Stock originally purchased
such shares from the Company at prices ranging from $4.56 to $4.95 per share or
through the exchange of one unit of limited partnership interest in the
Anti-Gene Development Group. There can be no assurance that claims asserting
violations of federal or state securities laws will not be asserted by any of
these shareholders against the Company or that certain holders will not prevail
against the Company in the assertion of such claims, thereby compelling the
Company to repurchase their shares. If all of the holders of the 22,021 shares
successfully asserted claims against the Company, the Company would be required
to pay these holders approximately $100,000, plus approximately one unit of
limited partnership interest in Anti-Gene Development Group, plus approximately
$44,000 in statutory interest. The rescission offer is not being made to holders
of 192,603 shares of the Company's Common Stock who reside in the states of
California and Nevada because the Company believes that its potential liability
to these shareholders has been eliminated by the running of applicable statutes
of limitation. There can be no assurance, however, that claims asserting
violations of federal or state securities laws will not be asserted by any of
those shareholders or that certain holders will not prevail against the Company
in the assertion of such claims, compelling the Company to repurchase their
shares. If all of the holders of the 192,603 shares successfully asserted claims
against the Company, the Company would be required to pay these holders
approximately $218,450, plus approximately 54 units of limited partnership
interest in the Anti-Gene Development Group, plus approximately $193,000 in
statutory interest. Even if the Company were successful in defending any
securities laws claims, the assertion of such claims against the Company
additionally could result in costly litigation and significant diversions of
effort by the Company's management.
 
    SECURITIES LITIGATION.  Although the Company believes that its potential
liability under state securities laws for the sale of securities with inadequate
disclosure will be effectively eliminated by the Rescission Offering and the
running of applicable statutes of limitations, and that its potential liability
under federal securities laws has been effectively eliminated by the running of
applicable statutes of limitations, there can be no assurance that claims
asserting violations of state or federal securities laws based on the facts
underlying the Rescission Offer will not be asserted. A successful claim brought
against the Company could have a material adverse effect on the Company's
business, financial condition and results of operation. Even unsuccessful claims
could result in costly litigation and significant diversions of effort by the
Company's management.
 
    DEVELOPMENT STAGE COMPANY; HISTORY OF OPERATING LOSSES.  The Company is a
development stage biotechnology company. Since its inception in 1980 through
December 31, 1996, the Company had incurred losses of $12,425,483, substantially
all of which resulted from expenditures related to research and development and
general and administrative expenses. The Company has not generated any material
revenues from product sales to date, and there can be no assurance that material
revenues from product sales will ever be achieved. Moreover, even if the Company
does realize revenues from product sales, the Company nevertheless expects to
incur significant operating losses over the next several years. The financial
statements accompanying this Prospectus have been prepared assuming that the
Company will continue as a going concern. The Company's ability to achieve a
profitable level of operations in the future
 
                                       18

<PAGE>
will depend in large part on the completion of product development of its
antisense and/or drug delivery products, obtaining regulatory approvals for such
products and bringing several of these products to market. The likelihood of the
long-term success of the Company must be considered in light of the expenses,
difficulties and delays frequently encountered in the development and
commercialization of new pharmaceutical products, competitive factors in the
marketplace as well as the burdensome regulatory environment in which the
Company operates. There can be no assurance that the Company will ever achieve
significant revenues or profitable operations. See "Selected Financial Data" and
"Management's Discussion and Analysis of Results of Operations and Financial
Condition."
 
    TECHNOLOGICAL UNCERTAINTY; EARLY STAGE OF PRODUCT DEVELOPMENT; NO ASSURANCE
OF REGULATORY APPROVALS. The Company's proposed products are in the pre-clinical
stage of development and will require significant further research, development,
clinical testing and regulatory clearances. The Company has no products
available for sale other than research reagents and does not expect to have any
products resulting from its research efforts commercially available for at least
several years. None of the Company's proposed products has been tested in
humans, nor has the Company filed an Investigational New Drug Application
("IND") with the United States Food and Drug Administration ("FDA") on any of
its products currently under research and development. The Company's proposed
products are subject to the risks of failure inherent in the development of
products based on innovative technologies. These risks include the possibilities
that some or all of the proposed products could be found to be ineffective or
toxic, or otherwise fail to receive necessary regulatory clearances; that the
proposed products, although effective, will be uneconomical to manufacture or
market; that third parties may now or in the future hold proprietary rights that
preclude the Company from marketing its products; or that third parties will
develop and market a superior or equivalent products. Accordingly, the Company
is unable to predict whether its research and development activities will result
in any commercially viable products or applications. Furthermore, due to the
extended testing and regulatory review process required before marketing
clearance can be obtained, the Company does not expect to be able to
commercialize any therapeutic drug for at least several years, either directly
or through any potential corporate partners or licensees. Although the Company
and others have demonstrated the effectiveness of antisense compounds in living
cells and, in some cases, in animal models, none of the Company's proposed
products has been tested in humans and there can be no assurance that the
Company's proposed products will prove to be safe or effective in humans or will
receive the regulatory approvals that are required for commercial sale.
 
    NEED FOR ADDITIONAL FUNDING; UNCERTAINTY OF ACCESS TO CAPITAL.  The Company
will require substantial funds for further development of its potential products
and to commercialize any products that may be developed. The Company's capital
requirements depend on numerous factors, including the progress of its research
and development programs, the progress of pre-clinical and clinical testing, the
time and cost involved in obtaining regulatory approvals, the cost of filing,
prosecuting, defending and enforcing patent claims and other intellectual
property rights, competing technological and market developments and the ability
of the Company to establish collaborative arrangements. The Company has no
current anticipated sources of funding beyond the proceeds of the proposed Unit
Offering. There can be no assurance that the Company will successfully complete
the proposed Unit Offering on terms and conditions acceptable to the Company.
The Company believes that its existing capital resources, including the
estimated net proceeds of that offering, will be sufficient to satisfy its
current and projected funding requirements for at least 24 months from the date
of this Prospectus. The Company anticipates that after 24 months, it will
require substantial additional capital. Moreover, if the Company experiences
unanticipated cash requirements during the next 24 months, including without
limitation the tender to the Company of a significant number of shares of its
Common Stock in connection with this rescission offering, the Company could
require additional capital to fund its operations, continue research and
development programs and to continue the pre-clinical and clinical testing of
its potential products and to commercialize any products that may be developed.
The Company may seek such additional funding through public or private
financings, collaborative arrangements, or other arrangements with third
parties. There can be no assurance that additional funds will be available on
acceptable terms, if at all. The Company may receive additional funds upon the
 
                                       19

<PAGE>
exercise from time to time of the warrants to be sold in its unit offering and
other outstanding warrants and stock options, but there can be no assurance that
any such warrants or stock options will be exercised or that the amounts
received will be sufficient for the Company's purposes. If additional funds are
raised by issuing equity securities, further substantial dilution to existing
shareholders may result. If adequate funds are not available, the Company may be
required to delay, scale back or eliminate one or more of its development
programs, or to obtain funds by entering into arrangements with collaborative
partners or others that may require the Company to relinquish rights to certain
of its products or technologies that the Company would not otherwise relinquish.
See "Management's Discussion and Analysis of Financial Condition and Results of
Operations."
 
    UNCERTAINTY OF NOTE VALUE AND PAYMENT.  The Company has been unprofitable
since its inception and has received no material revenues from the sale of
products or other sources. The Company does not expect material revenues in the
near term. The proceeds of the Company's proposed Unit Offering are the only
source of capital potentially available in the near term to the Company, other
than its existing cash and cash equivalents. There can be no assurance that the
proposed Unit Offering will be successfully undertaken by the Company. Even if
successful, although the Company's management enjoys broad discretion with
respect to the use of proceeds from the Unit Offering, there can be no assurance
that proceeds will be applied to the payment of the Notes or that any proceeds
will be available therefor upon the maturity of the Notes. Moreover, based on
the Company's current operating plan, if the Company experiences unanticipated
cash requirements during the next 24 months, including without limitation cash
required to pay holders of a significant number of shares of its Common Stock in
connection with the rescission offering, the Company could require significant
additional capital to fund operations, continue research and development
programs, pre-clinical and clinical testing of its potential antisense and drug
delivery compounds, commercialize any products that may be developed and make
payments on the Notes. There can be no assurance that, however, that additional
funds will be available, if at all.
 
    Although shares of the Company's Common Stock will be pledged to secured
payment of the Notes by the Company, there previously has been no public market
for the Company's Common Stock and there can be no assurance an active public
market for the Common Stock will be developed or sustained after the Rescission
Offer. In addition, even if such a public market does develop, the obligations
of the Pledgors to pledge shares are limited to shares held of record by the
Pledgors as of the date of this Prospectus and there can be no assurance that
the value of the Company's Common Stock on such public market will be at levels
so that the shares subject to the pledge will be sufficient to satisfy the
obligations of the Company in the event of a default by the Company in the
payment of the Notes. Regardless of the sufficiency of the pledged shares, the
Pledgors have no personal recourse liability on the Notes.
 
    The Notes are being issued pursuant to an exemption from the Trust Indenture
Act of 1939 and the protective provisions of the Act will not apply to holders
of the Notes.
 
    LACK OF OPERATING EXPERIENCE.  To date, the Company has engaged exclusively
in the development of pharmaceutical technology. Although members of the
Company's management have experience in biotechnology company operations, the
Company has no experience in manufacturing or procuring products in commercial
quantities or selling pharmaceutical products and has only limited experience in
negotiating, setting up and maintaining strategic relationships, conducting
clinical trials and other later-stage phases of the regulatory approval process.
There can be no assurance that the Company will successfully engage in any of
these activities. See "Management."
 
    MANUFACTURING.  The Company intends to undertake the manufacture of its
products through the clinical development phase. The Company has not previously
manufactured pharmaceutical products of any kind nor has it manufactured
antisense or drug delivery compounds in commercial quantities. Establishing
manufacturing facilities will require the retention of experienced personnel and
compliance with complex regulations relating to the manufacture of
pharmaceutical products. There is no assurance
 
                                       20

<PAGE>
that the Company will be successful in establishing and operating a
manufacturing facility. See "Business-- Manufacturing."
 
    DEPENDENCE ON THIRD PARTIES FOR CLINICAL TESTING, MANUFACTURING AND
MARKETING.  The Company does not have the resources and does not currently
intend to conduct later-stage human clinical trials itself or to manufacture all
of its proposed products for commercial sale. The Company therefore intends to
seek larger pharmaceutical company partners to conduct such activities for most
or all of its proposed products and to contract with third parties for the
manufacture of its proposed products for commercial sale. In connection with its
efforts to secure corporate partners, the Company will seek to retain certain
co-marketing rights to certain of its proposed products, so that it may promote
such products to selected medical specialists while its corporate partner
promotes these products to the general medical market. There can be no assurance
that the Company will be able to enter into any such partnering arrangements on
this or any other basis. In addition, there can be no assurance that either the
Company or its prospective corporate partners can successfully introduce its
proposed products, that they will achieve acceptance by patients, health care
providers and insurance companies, or that they can be manufactured and marketed
at prices that would permit the Company to operate profitably. With respect to
the Company's products, the Company may seek to enter into joint venture,
sublicense or other marketing arrangements with another party that has an
established marketing capability. There can be no assurance that the Company
will be able to enter into any such marketing arrangements with third parties,
or that such marketing arrangements would be successful. Failure to market its
products successfully would have a material adverse effect on the Company's
business and results of operations. In addition, the Company has no current
joint venture, strategic partnering or other similar agreements with
pharmaceutical companies, and there can be no assurance that the Company could
negotiate any such arrangements, on an acceptable basis or at all, if it chose
to do so. Accordingly, the commercial viability of the Company's proposed
products has not been independently evaluated by any independent pharmaceutical
company. See "Business--Manufacturing" and "Marketing Strategy."
 
    NEED TO COMPLY WITH GOVERNMENTAL REGULATION AND TO OBTAIN PRODUCT
APPROVALS.  The testing, manufacturing, labeling, distribution, marketing and
advertising of products such as the Company's proposed products and its ongoing
research and development activities are subject to extensive regulation by
governmental regulatory authorities in the United States and other countries.
The FDA and comparable agencies in foreign countries impose substantial
requirements on the introduction of new pharmaceutical products through lengthy
and detailed clinical testing procedures and other costly and time-consuming
compliance procedures. The Company's compounds require substantial clinical
trials and FDA review as new drugs. The Company cannot predict with certainty
when it might submit its products currently under development for regulatory
review. Once the Company submits its potential products for review, there can be
no assurance that FDA or other regulatory approvals for any pharmaceutical
products developed by the Company will be granted on a timely basis or at all. A
delay in obtaining or failure to obtain such approvals would have a material
adverse effect on the Company's business and results of operations. Failure to
comply with regulatory requirements could subject the Company to regulatory or
judicial enforcement actions, including, but not limited to, product recalls or
seizures, injunctions, civil penalties, criminal prosecution, refusals to
approve new products and withdrawal of existing approvals, as well as
potentially enhanced product liability exposure. Sales of the Company's products
outside the United States will be subject to regulatory requirements governing
clinical trials and marketing approval. These requirements vary widely from
country to country and could delay introduction of the Company's products in
those countries. See "Business--Drug Approval Process and Other Government
Regulation."
 
    DEPENDENCE ON KEY PERSONNEL.  The success of the Company's business will
depend to a large extent on the abilities and continued participation of certain
key employees, including Drs. Denis Burger, James Summerton, and Dwight Weller,
upon each of whom the Company holds key man life insurance. The Company has
entered into employment agreements with each of the key employees, which
agreements restrict their ability to compete with the Company for a period of
two years following termination of their
 
                                       21

<PAGE>
employment. The loss of any of these persons or of other key employees could
significantly delay the achievement of the Company's planned development
objectives. Competition for qualified personnel among pharmaceutical companies
is intense, and the loss of key personnel, or the inability to attract and
retain the additional, highly skilled personnel required for the expansion of
the Company's activities, could have a material adverse effect on the Company's
business and results of operations. See "Management."
 
    FORECLOSURE OF PLEDGE; POTENTIAL CHANGE OF CONTROL; ADVERSE EFFECT ON MARKET
PRICE.  The Company will issue the Notes in lieu of cash to rescinding
shareholders residing in Oregon and Colorado if the aggregate Rescission Price
of the shares tendered for rescission exceeds $1,500,000. Certain officers and
directors of the Company, including Drs. Denis Burger, James Summerton and
Dwight Weller, have agreed to maintain as security for payment of the Notes
sufficient shares of Common Stock of the Company that the aggregate value of
such shares equals 120% of the outstanding principal amount of the Notes. The
directors and officers own, of record, 3,569,030 shares of the Common Stock of
the Company as of the date of this Prospectus, which will represent
approximately 40% of the Company's outstanding Common Stock if all Eligible
Offerees exercise their right to rescind. The Company's issuance of Notes in
connection with the Rescission Offer, together with a significant decline in the
market value of the Company's Common Stock, could result in the pledge of a
sufficient number of shares to effect a change of control of the Company upon a
default by the Company and foreclosure of the pledged shares. The sale of a
substantial number of shares of the Company's Common Stock could adversely
affect the market price of the Common Stock and the Company's ability to raise
capital in the future in the equity markets. There can be no assurance that key
personnel will be retained if parties acquire control of the Company through the
acquisition of substantial shares as a result of a foreclosure. See "Dependence
on Key Personnel."
 
    COMPETITION.  Competition in the area of pharmaceutical products is intense.
There are many companies, both public and private, including well-known
pharmaceutical companies, that are engaged in the development of products for
certain of the applications being pursued by the Company. The Company's probable
competitors in the antisense and drug delivery fields include Glaxo Ltd.
("Glaxo"), Boehringer Ingelheim Inc. ("Boehringer Ingelheim"), Gilead Sciences
Inc. ("Gilead"), Hybridon Inc. ("Hybridon"), ISIS Pharmaceuticals, Inc.
("ISIS"), Lynx Therapeutics Inc. ("Lynx"), Cygnus, Inc. (Cygnus"), Biovail
Corporation International ("Biovail"), and Noven Pharmaceuticals, Inc.
("Noven"), among others. Most of these companies have substantially greater
financial, research and development, manufacturing and marketing experience, and
resources than the Company does and represent substantial long-term competition
for the Company. Such companies may succeed in developing pharmaceutical
products that are more effective or less costly than any that may be developed
by the Company.
 
    Factors affecting competition in the pharmaceutical industry vary depending
on the extent to which the competitor is able to achieve a competitive advantage
based on patented or proprietary technology. If the Company is able to establish
and maintain a significant patent position with respect to its antisense
compounds and drug delivery technology, its competition will likely depend
primarily on the effectiveness of the products and the number, gravity and
severity of unwanted side effects, if any, with its products as compared to
alternative products.
 
    The industry in which the Company competes is characterized by extensive
research and development efforts and rapid technological progress. Although the
Company believes that its patent position may give it a competitive advantage
with respect to its proposed antisense compounds and drug delivery products, new
developments are expected to continue and there can be no assurance that
discoveries by others will not render the Company's potential products
noncompetitive. The Company's competitive position also depends on its ability
to attract and retain qualified scientific and other personnel, develop
effective products, implement development and marketing plans, obtain patent
protection, and secure adequate capital resources. See "Business--Competition."
 
   
    PATENTS AND PROPRIETARY RIGHTS.  The Company believes that its ultimate
success will depend in part on the strength of its existing patents and
additional patents that it files in the future. The Company owns
    
 
                                       22

<PAGE>
   
eleven US patents and nine foreign patents covering various aspects of its
NEU-GENES technology, and additional patent applications are pending in the US
and Europe, Japan, Australia, and Canada. The Company has filed patent
applications covering the basic compositions of matter, methods of synthesis,
and medical uses of CYTOPORTER compounds. Although the Company believes that its
technology is adequately protected, there is no assurance that any existing or
future patents will survive a challenge or will otherwise provide meaningful
protection from competition. There is also no assurance that the Company will
have the financial resources to provide a vigorous defense of its patent
position, if challenged or that the practice of its patented and proprietary
technology will not infringe third-party patents. If an actual infringement were
instituted against the Company, there can be no assurance that the Company would
have the financial ability to defend the action or that the action would not
have an adverse effect on the Company. The Company's success will also depend on
its ability to avoid infringement of patent or other proprietary rights of
others or that it will be able to obtain any technology licenses it may require
in the future. See "Business--Patent and Proprietary Rights."
    
 
    RISK OF PRODUCT LIABILITY.  Clinical trials or marketing of any of the
Company's potential pharmaceutical products may expose the Company to liability
claims from the use of these products. The Company currently intends to obtain
product liability insurance at the appropriate time; however, there can be no
assurance that the Company will be able to obtain or maintain insurance on
acceptable terms for its clinical and commercial activities or that such
insurance would be sufficient to cover any potential product liability claim or
recall. Failure to have sufficient coverage could have a material adverse effect
on the Company's business and results of operations.
 
    CONTROL BY EXISTING SHAREHOLDERS.  The Company's officers, directors and
principal shareholders, and certain of their affiliates, beneficially own 46% of
the Company's outstanding Common Stock. If all Eligible Offerees exercise their
right to rescind, the Company's officers, directors, and principal shareholders,
will beneficially own 52% of the Company's then outstanding Common Stock. Such
concentration of ownership may have the effect of delaying or preventing a
change in control of the Company. Additionally, these shareholders will have
significant influence over major corporate transactions as well as the election
of directors of the Company and control over Board decisions. See "Principal
Shareholders."
 
    ANTI-TAKEOVER EFFECTS OF CERTAIN CHARTER PROVISIONS AND OREGON LAW.  Certain
provisions of the Company's Second Restated Articles of Incorporation and Bylaws
could discourage potential acquisition proposals, could delay or prevent a
change in control of the Company and could make removal of management more
difficult. Such provisions could diminish the opportunities for a shareholder to
participate in tender offers, including tender offers that are priced above the
then-current market value of the Common Stock. The provisions may also inhibit
increases in the market price of the Common Stock and Warrants that could result
from takeover attempts. For example, the Board of Directors of the Company,
without further shareholder approval, may issue up to 2,000,000 shares of
Preferred Stock, in one or more series, with such terms as the Board of
Directors may determine, including rights such as voting, dividend and
conversion rights which could adversely affect the voting power and other rights
of the holders of Common Stock. Preferred Stock thus may be issued quickly with
terms calculated to delay or prevent a change in control of the Company or make
removal of management more difficult. Additionally, the issuance of Preferred
Stock may have the effect of decreasing the market price of the Common Stock.
The Oregon Control Share Act and Business Combination Act limit the ability of
parties who acquire a significant amount of voting stock to exercise control
over the Company. These provisions may have the effect of lengthening the time
required for a person to acquire control of the Company through a proxy contest
or the election of a majority of the Board of Directors and may deter efforts to
obtain control of the Company. Finally, the Company's Board of Directors is
divided into two classes, each of which serves for a staggered two-year term,
which may make it more difficult for a third party to gain control of the
Company's Board of Directors. See "Description of Securities."
 
                                       23

<PAGE>
    NO PRIOR PUBLIC MARKET.  There previously has been no public market for the
Company's Common Stock or Warrants. There can be no assurance that an active
public market for the Common Stock or Warrants will develop or be sustained
after the proposed Unit Offering by the Company or that the Company will
successfully complete the Unit Offering. All of the Company's outstanding shares
of Common Stock, other than those issued in connection with the Company's Unit
Offering, are "restricted securities," which means that such shares are not
freely tradeable and may not be offered or sold at any time unless the
transaction is registered under the 1933 Act or an exemption from registration
is available. A decision not to accept the Rescission Offer will not affect the
restricted status of the Common Stock held by any Eligible Offeree. Although the
Company intends to apply to the NASDAQ Stock Market's National Market for
listing of its Common Stock and warrants issued in connection with the Unit
Offering, no assurance can be given that a public market for the Common Stock
will develop in the foreseeable future or, should a market develop, that
prevailing market prices will exceed those paid by Eligible Offerees for the
Common Stock.
 
    ABSENCE OF DIVIDENDS.  The Company has never paid cash dividends on its
Common Stock and does not anticipate paying cash dividends in the foreseeable
future. See "Dividend Policy."
 
                         DIVIDEND POLICY OF THE COMPANY
 
    The Company has not declared or paid cash dividends on its Common Stock. The
Company currently intends to retain all future earnings to fund the operation of
its business and, therefore, does not anticipate paying dividends in the
foreseeable future. Future cash dividends, if any, will be determined by the
Board of Directors.
 
                         CAPITALIZATION OF THE COMPANY
 
    The following table sets forth the capitalization of the Company as of
December 31, 1996 (i) on an actual basis, (ii) as adjusted to reflect the
receipt and application of the estimated net proceeds from the sale of the
1,500,000 Units offered by the Company at an assumed initial offering price of
$9.00 per Unit, and (iii) as adjusted to give effect to the Rescission Offer;
assuming that the interest component maintains a constant proportion of the
total Rescission Price.
 

<TABLE>
<CAPTION>
                                                                          DECEMBER 31, 1996
                                                    -------------------------------------------------------------
                                                       ACTUAL      AS ADJUSTED(2)  AS ADJUSTED(3)  AS ADJUSTED(4)
                                                    -------------  --------------  --------------  --------------
<S>                                                 <C>            <C>             <C>             <C>
Long-term debt, including current portion.........  $    --         $    --         $    --         $  3,746,623
                                                    -------------  --------------  --------------  --------------
Common stock subject to rescission................      3,121,965      3,121,965       2,229,401         --
Shareholders' equity:
    Preferred stock, $0.0001 par value: 2,000,000
      shares authorized; no shares issued and
      outstanding, actual and as adjusted(1)......       --              --              --              --
    Common stock, $0.0001 par value: 50,000,000
      shares authorized; 7,486,790 shares issued
      and outstanding, actual; 8,986,790 shares
      issued and outstanding, as
      adjusted(2)(3)(4)...........................            749            899             899             899
    Additional paid in capital....................     13,220,861     24,828,211      24,828,211      24,828,211
    Deficit accumulated during the development
      stage.......................................    (12,425,483)   (12,425,483)    (13,032,917)    (14,550,141)
                                                    -------------  --------------  --------------  --------------
    Total shareholders' equity....................        796,127     12,403,627      11,796,193      10,278,969
                                                    -------------  --------------  --------------  --------------
Total capitalization..............................  $     796,127   $ 12,403,627    $ 11,796,193    $ 10,278,969
                                                    -------------  --------------  --------------  --------------
                                                    -------------  --------------  --------------  --------------
</TABLE>

 
- ------------------------
 
(1) Reflects an amendment to the Company's Articles of Incorporation that was
    effective November 4, 1996, authorizing the issuance of up to 2,000,000
    shares of Preferred Stock.
 
                                       24

<PAGE>
(2) Excludes 1,551,261 shares of Common Stock issuable upon exercise of stock
    options and warrants outstanding as of December 31, 1996, at a weighted
    average exercise price of $4.66 per share. Also excludes 209,506 shares
    reserved for future issuance pursuant to the Company's Stock Incentive Plan.
    See "Management--Stock Incentive Plan" and Note 3 of Notes to Financial
    Statements.
 
(3) Assumes that shares with an aggregate Rescission Price of $1,500,000 are
    tendered for rescission, which represents the cash portion of the Company's
    potential payments under the Rescission Offer.
 
(4) Assumes that shares with an aggregate Rescission Price of $5,246,623 are
    tendered for rescission, the first $1.5 million of which is paid in cash and
    the next $3,746,623 is paid through the issuance of the Company's one and
    one-half year to three-year 9% notes.
 
                                       25

<PAGE>
                     SELECTED FINANCIAL DATA OF THE COMPANY
 
    The Selected Financial Data set forth below for the years ended December 31,
1995 and 1996, and for the period from July 22, 1980 (inception) through
December 31, 1996, and with respect to the Balance Sheet Data at December 31,
1995 and 1996 are derived from, and are qualified by reference to, the audited
Financial Statements and related Notes thereto included elsewhere in this
Prospectus and should be read in conjunction with those audited Financial
Statements and Notes thereto. The Selected Financial Data set forth below are
qualified by reference to, and should be read in conjunction with, "Management's
Discussion and Analysis of Financial Condition and Results of Operations" and
the Financial Statements and Notes thereto included elsewhere in this
Prospectus.
 
   

<TABLE>
<CAPTION>
                                                                           YEAR ENDED
                                                                          DECEMBER 31,
                                                                 ------------------------------
                                                                      1995            1996
                                                                 --------------  --------------     PERIOD FROM
                                                                                                   JULY 22, 1980
                                                                                                    (INCEPTION
                                                                                                      THROUGH
                                                                                                 DECEMBER 31, 1996
                                                                                                 -----------------
                                                                                                    (UNAUDITED)
<S>                                                              <C>             <C>             <C>
STATEMENTS OF OPERATIONS DATA:
Revenues, from grants and research contracts...................  $       82,500  $       27,227   $       669,497
                                                                 --------------  --------------  -----------------
Operating expenses:
  Research and development.....................................       2,097,796       1,729,554         9,007,811
  General and administrative...................................         609,723         613,811         4,549,583
                                                                 --------------  --------------  -----------------
    Total operating expenses...................................       2,707,519       2,343,366        13,557,394
                                                                 --------------  --------------  -----------------
Other income...................................................          68,133         228,776           446,176
                                                                 --------------  --------------  -----------------
Net loss.......................................................  $   (2,556,886) $   (2,087,362)  $   (12,425,483)
Net loss per share(1)..........................................  $        (0.37) $        (0.25)
                                                                 --------------  --------------
                                                                 --------------  --------------
Shares used in per share calculation(1)........................         982,459       8,233,548
                                                                 --------------  --------------
                                                                 --------------  --------------
</TABLE>

    
 

<TABLE>
<CAPTION>
                                                                           DECEMBER 31, 1996
                                      DECEMBER 31,   -------------------------------------------------------------
                                          1995          ACTUAL      AS ADJUSTED(2)  AS ADJUSTED(3)  AS ADJUSTED(4)
                                      -------------  -------------  --------------  --------------  --------------
<S>                                   <C>            <C>            <C>             <C>             <C>
BALANCE SHEET DATA
Working capital.....................        646,814      2,738,677     14,346,177      12,646,177      12,846,177
Total assets........................      2,324,736      4,248,899     15,856,399      14,356,399      14,356,399
Common stock subject to
  rescission........................      3,121,965      3,121,965      3,121,965       2,229,401         --
Deficit accumulated during the
  development stage.................    (10,338,121)   (12,425,483)   (12,425,483)    (13,032,917)    (14,550,141)
Total shareholders' equity
  (deficit).........................     (1,051,293)       796,127     12,403,627      11,796,193      10,276,969
</TABLE>

 
- ------------------------
 
(1) See Note 2 of Notes to Financial Statements for an explanation of the
    determination of the number of shares used in computing net loss per share.
 
(2) Adjusted to give effect to the application of the estimated net proceeds of
    the Company's Unit Offering based upon an assumed initial public offering
    price of $9.00 per Unit. See "Use of Proceeds" and "Management's Discussion
    and Analysis of Financial Condition and Results of Operations."
 
(3) Assumes that shares with an aggregate Rescission Price of $1.5 million are
    tendered for rescission, which represents the cash portion of the Company's
    potential payments under the rescission offer.
 
(4) Assumes that shares with an aggregate Rescission Price of $5,246,623 are
    tendered for rescission, the first $1.5 million of which is paid in cash and
    the next $3,746,623 is paid through the issuance of the Company's one and
    one-half year to three-year 9% notes.
 
                                       26

<PAGE>
          MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
                    AND RESULTS OF OPERATIONS OF THE COMPANY
 
OVERVIEW
 
   
    From its inception in July 1980, the Company has devoted its resources
primarily to fund its research and development efforts. The Company has been
unprofitable since inception and, other than limited interest and grant revenue,
has had no material revenues from the sale of products or other sources, and
does not expect material revenues for at least the next 12 months. The Company
expects to continue to incur losses for the foreseeable future as it expands its
research and development efforts. As of December 31, 1996 the Company's
accumulated deficit was $12,425,483.
    
 
   
    The Company expects to use approximately $5 million of the net proceeds of
the Unit Offering for pre-clinical development and the clinical trial phases of
the Company's near-term therapeutic programs. The Company intends to increase
its research staff as it prepares to initiate pre-clinical studies and file INDs
for RESTEN-NG and CYCLOSPORIN-CP in 1997. The Company's administrative staff
will be supplemented as needed to support the research and development
activities, to assure compliance with governmental regulatory requirements, and
to develop and establish strategic pharmaceutical alliances.
    
 
RESULTS OF OPERATIONS
 
   
    YEAR ENDED DECEMBER 31, 1995 COMPARED WITH YEAR ENDED DECEMBER 31, 1996. The
Company had revenues from research contracts of $82,500 and $27,227 for the
years ended December 31, 1995 and 1996 respectively. Revenues for both time
periods were derived from research collaborations with outside organizations,
and the decrease between the current and prior year periods was due primarily to
the completion of a collaborative research program in 1996. Operating expenses
were $2,707,519 in 1995 and $2,343,365 in 1996. The decrease in operating
expenses was due to a reduction in staff and other efficiencies that resulted
from a shift in focus of the Company's research to pre-clinical development.
General and administrative expenses, however, remained relatively constant, with
$609,723 in 1995 and $613,811 in 1996. Other income increased from $68,133 in
1995, to $228,776 in 1996, primarily due to the sale of short term investments
and increased interest income in 1996.
    
 
LIQUIDITY AND CAPITAL RESOURCES
 
   
    The Company has financed its operations since inception primarily through
private equity sales totaling $16,340,342 and grants and contract research
funding of $689,497 from various sources. The Company's cash and cash
equivalents were $680,892 at December 31, 1995 and $3,011,229 at December 31,
1996. The increase of $2,330,337 was due to net proceeds from the sale of the
Company's Common Stock of approximately $4,031,532 offset by the use of
approximately $1,608,088 for operations in 1996.
    
 
    The Company's future expenditures and capital requirements will depend on
numerous factors, including without limitation, the progress of its research and
development programs, the progress of its preclinical and clinical trials, the
time and costs involved in obtaining regulatory approvals, the cost of filing,
prosecuting, defending and enforcing any patent claims and other intellectual
property rights, competing technological and market developments, the ability of
the Company to establish collaborative arrangements and the terms of any such
arrangements, and the costs associated with commercialization of its products.
The Company's cash requirements are expected to continue to increase
significantly each year as it expands its activities and operations. There can
be no assurance, however, that the Company will ever be able to generate product
revenues or achieve or sustain profitability. See "Risk Factors."
 
   
    The proceeds of this offering are the only source of capital currently
available to the Company, other than existing cash and cash equivalents. See
"Use of Proceeds." The Company believes that the estimated net proceeds from
this offering and existing cash and cash equivalents will satisfy its budgeted
cash requirements for at least the next 24 months based upon the Company's
current operating plan. This plan
    
 
                                       27

<PAGE>
   
shows that at the end of the 24-month period, the Company will require
substantial additional capital. Moreover, if the Company experiences
unanticipated cash requirements during the 24-month period, including without
limitation, cash required to pay the holders of a significant number of shares
of Common Stock in connection with the Company's proposed rescission offering,
the Company could require additional capital to fund operations, continue
research and development programs and pre-clinical and clinical testing of its
potential antisense and drug delivery products and commercialize any products
that may be developed. See "Risk Factors--Potential Liability Arising From
Rescission Rights of Certain Shareholders." The Company may seek such additional
funding through public or private financings or collaborative or other
arrangements with third parties. There can be no assurance, however, that
additional funds will be available on acceptable terms, if at all. See "Risk
Factors--Additional Financing Requirements."
    
 
   
    The Company anticipates that it will satisfy the cash requirements of the
Rescission Offer from current cash and cash equivalents. Potential continuing
liability from the issuance of Notes related to the Rescission Offer could
result in substantial ongoing interest expense and adversely affect the
Company's access to capital markets. For example, the Company's issuance of
Notes would result in additional annual interest expense of approximately
$90,000 for each $1,000,000 of Notes issued, up to a maximum of approximately
$300,000 if all Eligible Offerees exercise their right to rescind. All such
potential increases in annual interest expense could have the effect of
increasing the Company's net loss. Additionally, the potential additional debt
would make it more difficult for the Company to satisfy minimum net worth
standards required to maintain the Company's Common Stock listing on the Nasdaq
National Market System. Finally, the potential additional debt could adversely
affect the Company's creditworthiness in the view of potential lenders and
investors, making it more difficult and expensive for the Company to obtain
needed financing.
    
 
                            BUSINESS OF THE COMPANY
 
GENERAL OVERVIEW
 
    ANTIVIRALS is a pioneer in the field of the gene-inactivating technology
referred to as ANTISENSE and has developed a patented class of antisense
compounds which may be useful in the treatment of a wide range of human
diseases. The Company also has developed new drug delivery technology which may
be useful with many FDA-approved drugs as well as with its antisense compounds.
The Company's drug development program has two areas of near-term focus:
 
    - NEU-GENE antisense compounds for selected applications, and
 
    - CYTOPORTER drug delivery engines for enhanced delivery of FDA-approved
      drugs with delivery problems.
 
   
    The Company's long-term product development program combines its NEU-GENE
and CYTOPORTER technologies to produce combination drugs with potential
applications for many diseases. The Company has filed patent applications
covering the basic compositions of matter, methods of synthesis and therapeutic
uses of NEU-GENES in the United States, Canada, Europe, Australia and Japan.
Eleven patents have issued in the United States and nine others have been
granted by the European Patent Office, and in Japan, Canada and Australia.
Additional patent applications, covering the Company's basic compositions of
matter, methods of synthesis and medical uses of CYTOPORTER compounds have been
filed.
    
 
    The first application of the Company's antisense technology is designed to
treat restenosis, a cardiovascular disease. The Company is currently in
pre-clinical development with this compound and expects to file an IND to begin
clinical trials in 1998. The Company's first planned drug delivery products
combine its CYTOPORTER delivery engine with two FDA-approved drugs that have
delivery problems. These drugs, cyclosporin and paclitaxel (Taxol-TM-), will
both be off patent by late 1997 and could have much
 
                                       28

<PAGE>
wider use if their delivery problems are reduced. The Company expects to file an
IND to begin clinical trials with its enhanced form of cyclosporin and to
initiate pre-clinical studies with its enhanced form of paclitaxel in 1998. See
"Drug Approval Process and Other Government Regulations."
 
   
    DRUG DESIGN AND DEVELOPMENT.  Most conventional drugs are chemicals designed
to induce or inhibit the function of a target protein molecule with as few side
effects as possible. Conventional drugs are not available for many diseases due
to their low level of selectivity for the specific disease target or because
they are difficult to deliver to their targets. These two issues, lack of
selectivity and poor delivery, may contribute to poor efficacy, unwanted side
effects or high toxicity, even at suboptimal dosages. Moreover, the development
of conventional drugs is usually time consuming and expensive, since thousands
of compounds must be produced and analyzed to find one with an acceptable
balance between efficacy and toxicity. Safe and effective therapeutics for viral
and host diseases have been particularly difficult to develop because these
diseases use the patient's own cellular machinery and therefore provide few
specific targets for therapeutic intervention that will not prove toxic to the
patient.
    
 
    Antisense technology has the potential to provide safe and effective
treatment for a wide range of diseases, including viral and host diseases. This
new approach uses synthetic compounds, or polymers, designed to inactivate
selected genetic sequences, thereby halting the disease process. Targeting these
genetic sequences provides the selectivity that is not available in conventional
drug development which typically targets proteins directly. The antisense
approach inhibits at the genetic level the mechanisms which underlie the
production of disease-producing proteins.
 
    To reach their therapeutic targets, many drugs must cross tissue and
cellular barriers. Drugs that have an intracellular site of action must cross
the lipid barrier of cellular membranes to move from the aqueous environment in
blood into the interior of target cells. Therefore, these drugs must achieve
solubility in both water and lipids. Since few compounds have these solubility
characteristics, many drug candidates are a compromise between inherent
solubility and effective delivery. This trade-off greatly reduces efficacy and
may significantly heighten toxicity of many drug candidates as well as many
FDA-approved drugs.
 
    The Company has developed two distinct technologies designed to address the
critical issues in drug development. The Company's NEU-GENE antisense technology
addresses the issue of drug selectivity, and its CYTOPORTER drug delivery
technology addresses delivery problems with both FDA-approved drugs and
antisense compounds. The characteristics of the patented structure of the
Company's NEU-GENE compounds distinguish its antisense technology from competing
technologies and provide the selectivity for a single disease target that is the
hallmark of all antisense technology. The Company's molecular engine,
CYTOPORTER, is designed to transport certain drugs with poor delivery
characteristics across the lipid barrier of cellular membranes into the interior
of cells to reach their targets.
 
NEAR-TERM PRODUCT DEVELOPMENT SUMMARY
 
   
    The first application of the Company's antisense technology is designed to
treat restenosis. The Company's first planned drug delivery products combine its
CYTOPORTER delivery engine with two FDA-approved drugs, paclitaxel (Taxol) and
cyclosporin, each of which the Company believes could have much broader usage if
its delivery problems were reduced.
    
 

<TABLE>
<CAPTION>
                                                              POTENTIAL
              COMPOUND                       DRUG             INDICATION              DEVELOPMENT STATUS
- -------------------------------------  -----------------  ------------------  ----------------------------------
<S>                                    <C>                <C>                 <C>
AVI-2221 NEU-GENE                      Resten-NG                 Restenosis   Pre-clinical studies in 1997 and
                                                                                IND filing expected in 1998
AVI-2401 CYTOPORTER                    Cyclosporin-CP       Transplantation   Pre-clinical studies in 1997 and
                                                                                IND filing expected in 1998
AVI-2301 CYTOPORTER                    Paclitaxel-CP                 Cancer   Pre-clinical studies expected in
                                                                                1998
</TABLE>

 
                                       29

<PAGE>
ANTISENSE--NEU-GENE
 
    TECHNICAL OVERVIEW
 
    GENETIC STRUCTURE AND FUNCTION.  All life forms contain genetic information
in molecules called DNA and RNA which comprise the operating instructions for
all life processes. The specific instructions are called genes, which are long
chains or strands of the four genetic bases: adenine, cytosine, guanine and
thymine, represented by the letters, A, C, G and T, respectively. The molecular
structures of these letters are complementary, such that A pairs with T, and C
pairs with G. Consequently, each genetic strand has the unique ability to bind
specifically to its complementary strand to form a duplex.
 
    The information encoded in the DNA by its sequence of genetic letters is
used to make proteins. To accomplish this, one strand (called the template
strand) of the duplex DNA is copied to make a new complementary strand, referred
to as messenger RNA. This messenger RNA is referred to as the SENSE strand
because it carries the information used to assemble a specific protein. See
"Figure 1" below. An ANTISENSE compound is a synthetic strand that is
complementary to a small portion of the messenger RNA. Antisense compounds pair
with their complementary messenger RNA sense strand to form a duplex, preventing
the message from initiating protein assembly. See "Figure 2" below.
 
                           FIGURE 1--GENETIC FUNCTION
 
                           [Genetic Function Diagram]
 
    GENE-TARGETED THERAPEUTICS.  Most human diseases arise from the function or
dysfunction of genes within the body, either those of pathogens, such as
viruses, or of one's own genes. New techniques in molecular biology have led to
the identification of the genes associated with most of the major human diseases
and to the determination of the sequence of their genetic letters. Using modern
methods of chemical synthesis, a genetic compound can be prepared that is
complementary to a critical SENSE sequence in a pathogen or pathogenic process.
When this complementary antisense compound binds tightly to the disease-causing
sequence, the selected protein is inhibited, and thus the pathogen or pathogenic
process is disabled. See "Figure 2" below.
 
               FIGURE 2--ANTISENSE INHIBITION OF GENETIC FUNCTION
 
                           [Antisense Inhibition Diagram]
 
    antisense compounds are composed of repeating structures or subunits that
are linked together forming a polymer, referred to as the antisense BACKBONE.
Each subunit carries a genetic letter (A, C, G, or T) that pairs with its
corresponding letter in the genetic target. Although the genetic letters are a
feature common to all antisense compounds, the structure of the subunits and the
linkage groups that string them together may differ greatly. These differences
in the subunits and the linkages define the different types of antisense
BACKBONES and their corresponding physical and biological properties. The
Company is distinguished from all other antisense companies by the
characteristics of its patented antisense BACKBONE. The subunits which carry the
genetic letters on the Company's BACKBONE are synthetic products rather than
modified natural materials. In addition, the linkages used to string the
subunits together carry no charge in the Company's BACKBONE. The Company
believes these differences may provide pharmaceutical advantages that are
critical for antisense drug development to meet the challenges of broad clinical
utility.
 
    FIRST-GENERATION COMPOUNDS.  The first gene-inactivating compounds had
BACKBONES composed of natural genetic materials and linkages. Development of
these compounds began in the late 1960s. As work continued in this new field, it
became increasingly clear that there were significant problems with these
structures. These natural compounds were degraded or broken down by enzymes in
the blood and within cells and had difficulty crossing cellular membranes to
enter the cells that contained their genetic target.
 
                                       30

<PAGE>
    SECOND-GENERATION COMPOUNDS.  To overcome these problems of degradation and
permeability, several research groups developed modified BACKBONES in the late
1970s which were designed to resist degradation by enzymes and to enter tissues
and cells more efficiently. The most common of these types, the phosphorothioate
BACKBONES used by ISIS Pharmaceuticals and Hybridon, use natural DNA subunits
linked together by a sulfur-containing, charged linkage.
 
    The Company was also extensively involved in developing second-generation
BACKBONES through the mid-1980s. After extensive investigation, however, the
Company concluded that even after optimization, these second-generation
compounds might lack the combination of properties desirable for broad clinical
utility. For this reason, the Company abandoned development of second-generation
BACKBONES in the mid-1980s and started development of third-generation BACKBONES
designed to address these drawbacks. Today, in spite of extensive progress in
the field, the Company believes that there remain serious limitations to
second-generation compounds due to problems with the stability, specificity,
cost effectiveness, and delivery of these compounds.
 
    NEU-GENE Third-generation Technology.  By the mid-1980s, the limitations of
the second-generation compounds led the Company to pursue the development of
antisense technology with improved pharmaceutical properties which could be
produced in a cost-effective manner. This effort culminated in the Company's
development of a new class of compounds having a BACKBONE of synthetic subunits
carrying each genetic letter, with each subunit linked together by a patented
uncharged linkage group. The synthetic subunits and linkages are not found in
nature, but rather were designed and synthesized to meet specific pharmaceutical
parameters. These patented third-generation agents, known as NEU-GENE compounds,
display advantageous pharmaceutical properties (stability, neutral charge, high
binding affinity and specificity). Moreover, they are made from less expensive,
more abundant materials, and the Company believes that they will cost
significantly less to produce than second-generation compounds.
 
    The Company and others have shown in cell culture and animal studies that
NEU-GENE compounds inhibit targeted genetic sequences. With these scientific
benchmarks in place, the Company's objective is to develop its third-generation
antisense compounds into effective and affordable therapeutics for major
infectious and host diseases.
 
    PHARMACEUTICAL PROPERTIES OF ANTISENSE COMPOUNDS.  If antisense compounds
are to become widely applicable pharmaceutical compounds, the following
challenges must be addressed.
 
    - Stability: resistance to enzymatic degradation both in blood and inside
      cells
 
    - Efficacy: ability to inhibit expression of the target gene
 
    - Specificity: binding restricted to the selected target, reducing toxicity
 
    - Cost effectiveness: manufacturing efficiency which allows a broad range of
      applications
 
    - Delivery: ability to cross tissue and cellular barriers in order to reach
      targeted genetic sequences
 
    The Company's core technology differentiates it from others developing
gene-inactivating compounds. The Company believes its principal competitive
advantage in the antisense area is the chemical structure of the NEU-GENE
BACKBONE which was developed to address all of the above parameters.
 
    STABILITY.  Biological stability is principally determined by the degree of
resistance to enzymatic degradation. Because the NEU-GENE BACKBONE is a unique
synthetic structure, the Company believes that there are no enzymes found in man
to degrade it. The Company has conducted studies indicating that these agents
are stable in blood and are stable to a broad range of degradative enzymes.
 
    EFFICACY AND SPECIFICITY.  Efficacy refers to the efficiency with which the
antisense compounds block selected protein production. In a direct comparison
with second-generation compounds conducted by the Company, its NEU-GENE
compounds exhibited significantly better binding to both RNA and DNA, as well
 
                                       31

<PAGE>
as substantially greater inhibition of the activity of targeted genetic
sequences. Specificity can be assessed by comparing target inactivation of
perfectly paired sequences and mispaired sequences. In the Company's direct
comparison studies, NEU-GENE compounds exhibited substantially greater
specificity than all other BACKBONE types tested.
 
    COST EFFECTIVENESS.  The difficulty of synthesizing antisense compounds has
been a concern in the field since its inception. The cost of producing
gene-inactivating polymers depends to a considerable extent on the cost of the
subunits from which they are constructed. The Company believes that because of
abundant, low-cost materials, simpler production techniques and higher yields,
the subunits used for NEU-GENE synthesis will cost substantially less than those
used in the synthesis of second-generation BACKBONES. After the genetic subunits
are prepared, they must be assembled in a defined order to form the desired
gene-inactivating polymer. The Company believes that the total cost of
production of commercial quantities of NEU-GENES will be significantly less than
that of gene-inactivating compounds prepared from natural or modified subunits
by competitors.
 
    DELIVERY.  To reach their targets, antisense compounds must cross tissue and
cellular barriers, including cellular and nuclear membranes. Preliminary
research indicates that antisense compounds, including those of the Company, may
face delivery problems when addressing many diseases. Accordingly, the Company
has devoted substantial research effort to develop technology for delivering
NEU-GENES to the interior of the cell. See "Drug Delivery--CYTOPORTER."
 
    NEAR-TERM ANTISENSE PRODUCT DEVELOPMENT--RESTENOSIS
 
   
    The first application of the Company's antisense technology is designed to
treat restenosis, a cardiovascular disease. Restenosis results from the failure
of balloon angioplasty due to a rapid growth of smooth muscle cells leading to a
second blockage of a coronary artery. There are approximately 500,000 balloon
angioplasties done in the United States each year with a failure rate of
approximately 30% - 40%. During angioplasty, small metal supports, known as
stents, may be placed at the site of blockage to keep the artery open. Recent
studies suggest that stent placement may reduce the incidence of restenosis to
approximately 20%. Although balloon angioplasty may avoid expensive bypass
surgery if successful, restenosis may ultimately require the patient to undergo
bypass surgery. The Company has selected restenosis as its first antisense
product opportunity because the Company believes that delivery of NEU-GENE
compounds is achievable in this disease setting, NEU-GENE compounds have the
combination of other properties to address this disease and because the
restenosis market is estimated at more than $1 billion annually in the United
States.
    
 
   
    When a patient has a blocked coronary artery, a procedure called balloon
angioplasty is frequently used to remove the blockage. In this procedure a
balloon catheter is inserted in the artery up to the blockage and the balloon is
inflated to open the artery. The balloon increases the diameter of the channel
through the blocked portion of the artery. During this process, vascular cells,
including smooth muscle cells which underlie the blockage, may be damaged. This
process may result in rapid cell division leading to closure of the artery a
second time. Restenosis occurs in 30% - 40% of these procedures when stents are
not placed and cannot be predicted from patient to patient. Even when stents are
placed, the incidence of restenosis is significant. The precise mechanisms which
cause this reaction are not known. However, scientific evidence suggests that,
if the smooth muscle cells can be prevented from dividing for a few days until
the integrity of the artery is reestablished, restenosis could be prevented in a
significant number of cases. Although there are a few new clinical approaches
that attempt to prevent restenosis, none is very effective and all have
significant risks associated with them.
    
 
    There is scientific evidence that antisense compounds readily enter
scrape-damaged artery cells and the Company has demonstrated that its NEU-GENE
antisense compounds readily enter and function in scraped cells in the
laboratory. The Company has selected target genetic sequences, has produced drug
candidates, and has demonstrated that its NEU-GENE compounds inhibit cell
division in laboratory models
 
                                       32

<PAGE>
   
for this disease. Compound AVI-2221, Resten-NG, is now in pre-clinical
development for restenosis, and the Company expects to file an IND to begin
clinical trials in 1997. See "Drug Approval Process and Other Government
Regulations." The Company intends to co-develop its NEU-GENE restenosis compound
with a pharmaceutical partner. There can be no assurance, however, that the
Company will be able to attract any partnerships or establish any such
relationship on favorable terms, or at all.
    
 
DRUG DELIVERY--CYTOPORTER
 
    Since NEU-GENES are large molecules that do not readily make their way into
cells, the Company has been developing a delivery mechanism that would allow
NEU-GENES, as well as other drugs, to be transported directly into their
intercellular site of action. The Company has developed and has filed a patent
for a molecular engine, called CYTOPORTER, to transport drugs across the lipid
layers of cellular and endosomal membranes into the interior of cells. This
engine is powered by the acidic differential (pH gradient) across the endosomal
membrane, does not disrupt the membrane, and is disassembled into harmless
byproducts after carrying out its transport function.
 
    TECHNICAL OVERVIEW
 
    The body has protective barriers that shield it from penetration by foreign
agents. Two of these barriers, cell membranes and the outermost layer of the
skin, are composed of lipid layers (fat-like substances). The lipid composition
of these barriers prevents aqueous or water-soluble agents from the environment
or in the blood from penetrating into the interior of cells and interfering with
critical cellular functions. These lipid layers are the principal barriers to
effective drug delivery for many drugs that have an intracellular site of
action.
 
   
    For optimal delivery, a drug should penetrate readily into both the aqueous
compartments of the body (body fluids and the interior of cells) and into the
lipid layers which enclose those compartments. This is rarely achieved because
when lipid solubility is increased, water solubility is decreased, and vice
versa. In the past, to achieve delivery, the structure of a selected drug
candidate was chemically adjusted to produce a compromise in the solubility
profile (e.g., less than ideal water solubility in order to achieve some level
of lipid solubility). This trade-off has been successful with many drugs, but
markedly less successful for many others. Currently, a significant number of all
FDA-approved drugs have delivery problems, and many others never make it into
clinical development due to delivery problems.
    
 
    Small substances of low polarity can usually pass directly through the lipid
layers of cell membranes. This appears to be the principal route of entry for
most drugs without delivery problems. In contrast, substances with greater
polarity and/or larger molecular size generally enter cells by being taken up
and sequestered in a closed cellular compartment, or endosome, in a process
called endocytosis. In this process, the interior of the endosome is acidified
and the contents are exposed to degradative enzymes resulting in their
breakdown. This is a natural cellular mechanism that protects the interior of
the cell from exposure to foreign material.
 
    Drugs that are polar in nature or are of a larger molecular size must cross
the lipid membrane of the endosome before being degraded in order to gain entry
into the interior of the cell. Many drugs in this category fail to achieve entry
rapidly enough to be practical for pharmaceutical purposes.
 
    CYTOPORTER DRUG DELIVERY SOLUTION.  The Company believes it has developed an
effective drug delivery engine, called CYTOPORTER, to facilitate the transport
of polar and larger size drugs across the lipid barriers of the skin, cell
membranes, and endosomes into the interior of cells at a rate that is practical
to achieve pharmaceutical results. When drugs in this category are taken up by
cells, they are sequestered within an endosome surrounded by a lipid barrier.
The Company's CYTOPORTER drug delivery engine is designed to transport these
problem drugs from the endosome into the interior of cells without disruption of
the lipid membrane that traps them. CYTOPORTER is a synthetic peptide containing
specifically positioned acidic groups along its structure. In neutral
conditions, CYTOPORTER exists as a water-soluble
 
                                       33

<PAGE>
random form with its acidic groups exposed and hydrated. On acidification in the
endosome, CYTOPORTER undergoes a transition to a lipid-soluble, needle-like form
where the acidic groups are masked by associating as mated pairs, and other
polar groups are shielded from the environment. As the engine becomes lipid
soluble it penetrates across the surrounding lipid membrane. As it enters into
the interior of the cell, it encounters a neutral environment which induces a
transition back to a water-soluble form resulting in movement of the engine and
drug into the interior of the cell. See "Figure 3" below.
 
            FIGURE 3--CYTOPORTER DRUG DELIVERY AT THE CELLULAR LEVEL
 
                              [Drug Delivery Diagram]
 
    CYTOPORTER DRUG TRANSPORT MECHANISM.  In preparation for enhanced drug
delivery, the selected drug is chemically linked to the CYTOPORTER engine. This
process will be unique for each drug and must take into account each drug's mode
and site of action. Several steps are involved in the transport of the selected
drug from the blood or body fluids across lipid barriers into the interior of
target cells. After the drug is taken up by endocytosis, the endosome is
acidified as the cell attempts to degrade its contents. As this acidification
takes place, the engine converts from a water-soluble random form into a
lipophilic, needle-like form. As the engine converts to its lipophilic form, it
is PUSHED into the lipid membrane. Because the engine is longer than the
membrane is thick, continued entry pushes the leading end of the engine into the
interior of the cell. As the engine enters the neutral environment of the
interior of the cell, it reverts automatically to its random, water-soluble
form. This provides the motive force to PULL more of the engine across the
membrane. Finally, ionization and solvation of the engine as it enters the
interior pull the attached drug into the interior of the cell. The interior of
the cell contains enzymes which rapidly break down the engine into harmless
by-products. This is a natural process that results in freeing the drug to react
with its intracellular target.
 
    The Company believes that its CYTOPORTER delivery engine can be chemically
adjusted to accommodate a range of delivery challenges. The transition from
water to lipid solubility can be manipulated to afford a wide range of
transitions to accommodate various endosome characteristics. Moreover, the
Company believes that its CYTOPORTER can be adjusted to accommodate various drug
loads from modest polar drugs to the more challenging large molecular size
polymers like uncharged antisense compounds.
 
    CYTOPORTER APPLICATIONS.  The Company believes its CYTOPORTER molecular
engines may provide improved pharmaceutical properties for a wide variety of
drugs, including:
 
    - Improved aqueous solubility for lipophilic drugs, such as Taxol.
 
   
    - Improved transport of peptides from endosomes into the interior of cells
      (e.g., cyclosporin) and transport of antisense polymers, particularly
      non-charged types such as NEU-GENES.
    
 
    - Protection of polymer drugs from degradation by virtue of transport out of
      endosomes prior to the start of the degradation process.
 
    - Improved transport of drugs into cells of the brain by specialized
      CYTOPORTER engines designed to provide both transport across the
      blood/brain barrier and subsequent entry into the interior of the brain.
 
    - Delivery of highly cytotoxic drugs into bacteria living in an acidic
      environment, specifically H. PYLORI, a major cause of ulcers in the
      stomach.
 
    - Transdermal delivery of lipophilic drugs.
 
    TRANSDERMAL DRUG DELIVERY.  The Company believes that its CYTOPORTER drug
delivery engine may have the potential for transdermal delivery of selected
substances. Placing an acidic, lipid-soluble form of the engine with an attached
drug in contact with the surface of the skin results in the diffusion of the
drug-engine through the lipid layers of the outer barrier of the skin (the
extracellular matrix of the stratum
 
                                       34

<PAGE>
corneum). Upon contact with the aqueous compartment underlying the stratum
corneum, the drug-engine is drawn actively into this compartment through
progressive ionization and solvation of the engine in the neutral conditions of
this environment. This results in delivery of the attached drug into the
underlying tissues, with subsequent distribution throughout the body.
 
    NEAR-TERM DRUG DELIVERY PRODUCTS
 
    The Company has selected cyclosporin and paclitaxel (Taxol) as the initial
drugs to be combined with its CYTOPORTER delivery engine for its enhanced drug
products. Additionally, the Company plans to apply its drug delivery technology
to current drugs used to treat inflammation, pain, and infectious diseases. The
Company plans to work with pharmaceutical collaborators to bring its drug
delivery technology to the market in a timely fashion. The Company has not,
however, entered into any arrangements with pharmaceutical collaborators, and
there can be no assurance that the Company will be able to do so or that if
entered into, the arrangements will be successful in bringing the technology to
the market in a timely fashion.
 
    CYCLOSPORIN-CP.  Cyclosporin is a drug marketed by Sandoz AG whose patent
life expired in 1996. It is the transplantation anti-rejection drug of choice
worldwide, with an estimated market size of $1 billion. Difficulties with
delivery prevent broader systemic use and topical applications.
 
    Cyclosporin is an immunosuppressive drug that inhibits the function of
lymphocytes involved in mounting a rejection response in patients undergoing
organ transplantation. It has both poor solubility and poor delivery to its site
of action. Consequently, larger doses of the drug are required in order to
achieve a clinical level of effectiveness than if the drug readily reached its
site of action. These higher dosages lead to renal toxicity and other problems
that limit broader use. The Company believes that combining its CYTOPORTER drug
delivery engine with cyclosporin (Cyclosporin-CP) potentially would eliminate
these delivery difficulties, resulting in lower dosages, fewer side effects, and
broader usage. The Company expects to begin pre-clinical studies with
Cyclosporin-CP in 1997 and to file an IND to begin clinical trials with this
agent in 1998. There can be no assurance that the Company will be able to file
or obtain an approval for an IND in 1998 or at all.
 
   
    PACLITAXEL-CP.  Taxol is a Bristol-Myers Squibb drug whose patent life
expires in 1997. It is the largest selling cancer therapeutic worldwide, with
sales of approximately $580 million in 1995. However, severe solubility and
delivery problems greatly limit its use and effectiveness.
    
 
    Paclitaxel is indicated to treat ovarian cancer and is being used
experimentally to treat numerous cancers including breast cancer. The current
paclitaxel formulation is not readily soluble in aqueous solutions, requiring
the use of the solvent Cremophor-Registered Trademark-EL. Injection of the
drug/solvent combination causes hypersensitivity reactions, leaching of
plasticizer from PVC infusion bags, haziness of diluted solutions and the need
for in-line filters. The Company believes that combining its CYTOPORTER delivery
engine with paclitaxel (Paclitaxel-CP) could eliminate the need for solvent in
the formulation, thereby eliminating solvent-associated problems. This
development could result in more optimized dosing, a reduction in side effects,
and broader usage. The Company expects to begin pre-clinical trials of
Paclitaxel-CP in 1998.
 
LONG-TERM PRODUCT DEVELOPMENT PROGRAM--NEU-GENE/CYTOPORTER DRUG COMBINATIONS
 
    The following table summarizes the Company's broader drug development
program. These programs combine the Company's NEU-GENE antisense technology with
its CYTOPORTER drug delivery technology. For each indication, NEU-GENES have
been designed to target the disease process at the genetic level. The Company
has designed CYTOPORTER to deliver the NEU-GENE drugs to their intracellular
site of action. Although NEU-GENES may display clinical efficacy on their own,
the Company believes that broad use of NEU-GENES and other antisense compounds
will require a drug delivery strategy. CYTOPORTER drug
 
                                       35

<PAGE>
delivery engines were developed to facilitate the delivery of the NEU-GENE
BACKBONE and are currently being optimized for that purpose.
 
    All of the development programs listed below are in the research or lead
compound stage. Disease targets have been identified and NEU-GENE compounds have
been produced and tested in laboratory and/ or animal models. In some cases,
lead compounds have been produced which are undergoing optimization prior to
pre-clinical development. The Company believes that several of these compounds
may move into pre-clinical development in the next two years.
 
   

<TABLE>
<S>                    <C>                    <C>                    <C>
         INFECTIOUS DISEASE TARGETS                       HOST DISEASE TARGETS
- --------------------------------------------  --------------------------------------------
                       Potential Indications                         Potential Indications
                       ---------------------                         ---------------------
Development Program                           Development Program
- ---------------------                         ---------------------
HIV                    AIDS, HIV-I Infection  TNF Alpha              Inflammation
Hepatitis B, C         Hepatitis, Liver       Icam-1                 Inflammation
                       Cancer
Herpes Simplex Virus   Ocular, Genital        Telomerase             Cancer
                       Herpes
Cytomegalovirus        Retinitis
</TABLE>

    
 
    INFECTIOUS DISEASE TARGETS
 
   
    HUMAN IMMUNODEFICIENCY VIRUS ("HIV").  The Company has initiated a program
to produce and evaluate NEU-GENE agents directed at HIV targets. The Centers for
Disease Control ("CDC") estimated that, by the end of 1995, there were one
million HIV-infected persons in the United States and the cumulative number of
diagnosed AIDS cases approximated 500,000. The World Health Organization
estimated that worldwide there were approximately 10 million individuals
infected with HIV by the end of 1995. Currently, there are few FDA-approved
therapies for the treatment of HIV-infected individuals and drugs that are
available have significant toxic side effects.
    
 
   
    HEPATITIS B ("HBV").  The Company has initiated a program to produce and
evaluate NEU-GENE compounds directed at HBV targets. HBV is a major health
problem throughout the world, with epidemic infection levels in certain less
developed countries. HBV was estimated in 1995 to be the second leading cause of
death in the world. There are an estimated 300,000 new hepatitis infections in
the United States each year and approximately one million people with chronic
infection. Although there are effective vaccines against HBV, there are
currently no FDA-approved therapies for the treatment of chronic or acute HBV
infection.
    
 
    HEPATITIS C ("HCV").  The Company has initiated a program to produce and
evaluate NEU-GENE compounds directed at HCV targets. HCV is a major health
problem in many parts of the world, including the United States where there are
approximately 150,000 new infections each year (about 40% of all acute hepatitis
cases). The mechanism of transmission may involve the exchange of blood,
although the route of transmission in many cases is obscure. There are no
FDA-approved vaccines or therapeutic drugs for the treatment of HCV.
 
   
    HERPES SIMPLEX VIRUS ("HSV").  The Company is developing HSV NEU-GENE
compounds for the treatment of HSV type I and type II. Primary herpes infections
are usually severe and may involve skin, mucous membranes, conjunctivae or the
central nervous system. After remission of the initial infection, the virus
establishes a latent phase which is interrupted periodically by outbreaks or
herpetic lesions. Newborns can be infected at birth, which results in 50%
mortality, and survivors may suffer from permanent neurological damage.
Approximately 500,000 new cases each of genital herpes and oral herpes infection
occur annually in the United States. It is estimated that approximately 10
million Americans suffer from some form of primary or recurrent herpes infection
each year.
    
 
    CYTOMEGALOVIRUS ("CMV").  The Company is developing NEU-GENE compounds for
the treatment of CMV infections. CMV is a member of the herpes family of viruses
and is the most common cause of intrauterine and congenital infections in
newborns of infected mothers. CMV retinitis is a severe problem
 
                                       36

<PAGE>
in transplant patients and patients with immunosuppression (e.g., AIDS), often
leading to blindness and pneumonitis, one of the most lethal viral syndromes.
Current FDA-approved treatments for CMV retinitis suffer from dose-limiting side
effects and have been associated with the emergence of drug-resistant CMV
strains.
 
    HOST DISEASE TARGETS
 
   
    The Company is evaluating NEU-GENES for the treatment of inflammatory
diseases and cancer, two major host diseases. Inflammation is a crucial
component of a number of acute and chronic diseases. Although inflammation is a
key part of the normal physiological response to injury, alterations to the
normal inflammatory process often lead to inflammatory diseases. These
inflammatory disorders can affect practically every organ system in the body.
The interactions at the molecular level that cause inflammation are becoming
better understood and provide targets for intervention by antisense approaches.
Two families of potential targets include cellular mediators (TNF alpha) and
cellular adhesion molecules (ICAM-1), which are proteins involved in various
stages of the inflammatory process. The Company believes that by targeting
messenger RNA with NEU-GENE compounds, control of these mediators of
inflammation may be possible.
    
 
   
    TNF ALPHA.  TNF alpha has been implicated as a significant factor in
psoriasis, arthritis and other inflammatory disorders. Psoriasis is a serious
chronic, recurring skin disease that involves proliferation of keratinocytes
within the epidermal layer of the skin. Approximately six million individuals in
the United States are afflicted by psoriasis and approximately 200,000 new cases
are diagnosed annually. Current psoriasis therapies are varied but offer limited
results. The Company has demonstrated that its NEU-GENE compounds are effective
in inhibiting TNF alpha in laboratory and animal models of inflammation.
    
 
   
    ICAM-1.  ICAM-1 facilitates the migration of immune cells involved in both
acute and chronic inflammation. Over-production of ICAM-1 is specifically
implicated in a wide variety of inflammatory disorders, such as rheumatoid
arthritis, asthma, psoriasis, organ transplant rejection, and inflammatory bowel
disease. The Company has targeted NEU-GENES against the adhesion molecule ICAM-1
and is testing these compounds in models of inflammation.
    
 
    TELOMERASE.  Telomerase is an enzyme found in cancer cells but rarely in
normal cells and the Company believes that inhibiting it may provide a broad
general approach to treat most cancers. There are approximately one million new
cases of cancer of all types reported in the United States annually. This leads
to about 500,000 deaths in the United States attributed to cancer each year,
making it the country's second leading cause of death. The Company has developed
NEU-GENE compounds that block telomerase activity in model systems in the
laboratory.
 
COLLABORATIVE AGREEMENTS
 
    The Company believes that antisense and drug delivery technologies are
broadly applicable for the potential development of pharmaceutical products in
many therapeutic areas. To exploit its core technologies as fully as possible,
the Company's strategy is to enter into collaborative research agreements with
major pharmaceutical companies directed at specific molecular targets. It is
anticipated that collaborative research agreements may provide the Company with
funding for programs conducted by the Company aimed at discovering and
developing antisense compounds to inhibit the production of individual molecular
targets. Partners may be granted options to obtain licenses to co-develop and to
market drug candidates resulting from its collaborative research programs. The
Company intends to retain manufacturing rights to its antisense products. There
can be no assurance, however, it will be able to enter into collaborative
research agreements with large pharmaceutical companies on terms and conditions
satisfactory to the Company.
 
                                       37

<PAGE>
MANUFACTURING
 
    The Company believes that it has developed significant proprietary
manufacturing techniques which will allow large-scale, low-cost synthesis and
purification of NEU-GENES. Because the Company's NEU-GENE compounds are based
upon a malleable BACKBONE chemistry, the Company believes that NEU-GENE
synthesis will be more cost-effective than those of competing technologies. The
Company has established sufficient manufacturing capacity to meet immediate
research and development needs.
 
   
    The Company currently intends to retain manufacturing rights to all products
incorporating its proprietary and patented technology, whether such products are
sold directly by the Company or through collaborative agreements with industry
partners. The Company's current production capacity is insufficient for the
requirements of human clinical studies. Consequently, the Company intends to
contract with a Good Manufacuring Practices ("GMP") facility beginning in 1997
to produce its near term therapeutic candidates for pre-clinical and clinical
trial studies. There is no assurance, however, that the Company's plans will not
change as a result of unforeseen contingencies.
    
 
   
    In March 1993, the Company moved to its present laboratory facility. This
facility and the laboratory procedures followed by the Company have not been
formally inspected by the FDA and will have to be approved as products move from
the research phase through the clinical testing phase to commercialization. The
Company will be required to comply with FDA requirements for GMP in connection
with human clinical trials and commercial production. See "Drug Approval Process
and Other Government Regulations."
    
 
MARKETING STRATEGY
 
   
    The Company plans to market the initial products for which it obtains
regulatory approval, through marketing arrangements or other licensing
arrangements with large pharmaceutical companies. Implementation of this
strategy will depend on many factors, including the market potential of any
products the Company develops and the Company's financial resources. The Company
does not expect to establish a direct sales capability for therapeutic compounds
for at least the next several years. To market products that will serve a large,
geographically diverse patient population, the Company expects to enter into
licensing, distribution, or partnering agreements with pharmaceutical companies
that have large, established sales organizations. The timing of the Company's
entry into marketing arrangements or other licensing arrangements with large
pharmaceutical companies will depend on successful product development and
regulatory approval within the regulatory framework established by the Federal
Food, Drug and Cosmetics Act, as amended, and regulations promulgated
thereunder. Although the implementation of initial aspects of the Company's
marketing strategy may be undertaken before this process is completed, the
development and approval process typically is not completed in less than three
to five years after the filing of an investigational new drug application and
the Company's marketing strategy therefore may not be implemented for several
years. See "Drug Approval Process and Other Governmental Regulations." See "Risk
Factors--Dependence on Third Parties for Clinical Testing, Manufacturing and
Marketing."
    
 
PATENTS AND PROPRIETARY RIGHTS
 
   
    The proprietary nature of, and protection for, the Company's product
candidates, processes and know-how are important to its business. The Company
plans to prosecute and defend aggressively its patents and proprietary
technology. The Company's policy is to patent the technology, inventions, and
improvements that are considered important to the development of its business.
The Company also relies upon trade secrets, know-how, and continuing
technological innovation to develop and maintain its competitive position.
    
 
   
    The Company owns eleven US patents covering various polymer compositions
effective in sequence-specific binding to single-stranded nucleic acids,
subunits used in producing the polymers, therapeutic and diagnostic applications
of the polymers, combinatorial library compositions formed from the subunits,
and
    
 
                                       38

<PAGE>
   
polymer composition effective in sequence-specific binding to double-stranded
nucleic acid. The issued patents expire between 2008 and 2014. Corresponding
patent applications have been filed in Europe, Japan, Australia, and Canada, and
nine of these foreign applications have been granted as patents, with expiration
dates between 2006 and 2012. The Company has additional pending applications in
the area of its NEU-GENES technology, and has filed patent applications covering
the basic compositions of matter, methods of synthesis, and medical uses of
CYTOPORTER compounds. The Company intends to protect its proprietary technology
with additional filings as appropriate.
    
 
    There can be no assurance that any patents applied for will be granted or
that patents held by the Company will be valid or sufficiently broad to protect
the Company's technology or provide a significant competitive advantage, nor can
the Company provide assurance that practice of the Company's patents or
proprietary technology will not infringe third-party patents.
 
    Although the Company believes that it has independently developed its
technology and attempts to ensure that its technology does not infringe the
proprietary rights of others, if infringement were alleged and proven, there can
be no assurance that the Company could obtain necessary licenses on terms and
conditions that would not have an adverse effect on the Company. The Company is
not aware of any asserted or unasserted claims that its technology violates the
proprietary rights of any person. See "Risk Factors--Patents and Proprietary
Rights."
 
DRUG APPROVAL PROCESS AND OTHER GOVERNMENT REGULATION
 
    The production and marketing of the Company's products and its research and
development activities are subject to regulation for safety, efficacy and
quality by numerous governmental authorities in the United States and other
countries. In the United States, drugs are subject to rigorous regulation. The
Federal Food, Drug and Cosmetics Act, as amended, and the regulations
promulgated thereunder, as well as other federal and state statutes and
regulations, govern, among other things, the testing, manufacture, safety,
efficacy, labeling, storage, record keeping, approval, advertising and promotion
of the Company's proposed products. Product development and approval within this
regulatory framework take a number of years and involve the expenditure of
substantial resources. In addition to obtaining FDA approval for each product,
each drug manufacturing establishment must be registered with, and approved by
the FDA. Domestic manufacturing establishments are subject to regular
inspections by the FDA and must comply with GMP. To supply products for use in
the United States, foreign manufacturing establishments must also comply with
GMP and are subject to periodic inspection by the FDA or by regulatory
authorities in certain of such countries under reciprocal agreement with the
FDA.
 
    NEW DRUG DEVELOPMENT AND APPROVAL.  The United States system of new drug
approval is the most rigorous in the world. According to a February 1993 report
by the Congressional Office of Technology Assessment, it cost an average of $359
million and took an average of 15 years from discovery of a compound to bring a
single new pharmaceutical product to market. Approximately one in 1,000
compounds that enter the pre-clinical testing stage eventually makes it to human
testing and only one-fifth of those are ultimately approved for
commercialization. In recent years, societal and governmental pressures have
created the expectation that drug discovery and development costs can be reduced
without sacrificing safety, efficacy and innovation. The need to significantly
improve or provide alternative strategies for successful pharmaceutical
discovery, research and development remains a major health care industry
challenge.
 
    DRUG DISCOVERY.  In the initial stages of drug discovery, before a compound
reaches the laboratory, typically tens of thousands of potential compounds are
randomly screened for activity in an assay assumed to be predictive of a
particular disease process. This drug discovery process can take several years.
Once a "screening lead" or starting point for drug development is found,
isolation and structural determination are initiated. Numerous chemical
modifications are made to the screening lead (called "rational synthesis") in an
attempt to improve the drug properties of the lead. After a compound emerges
from the above
 
                                       39

<PAGE>
process, it is subjected to further studies on the mechanism of action and
further IN VITRO animal screening. If the compound passes these evaluation
points, animal toxicology is performed to begin to analyze the toxic effect of
the compound, and if the results indicate acceptable toxicity findings, the
compound emerges from the basic research mode and moves into the pre-clinical
phase. The Company has many compounds at the drug discovery phase and three
components that it expects to move to pre-clinical testing within 12 to 24
months.
 
    PRE-CLINICAL TESTING.  During the pre-clinical testing stage, laboratory and
animal studies are conducted to show biological activity of the compound against
the targeted disease, and the compound is evaluated for safety. These tests can
take up to three years or more to complete. The Company's restenosis compound
currently is in pre-clinical testing and the Company presently anticipates that
Cyclosporin-CP will enter this phase in 1997 and Paclitaxel-CP in 1998.
 
    INVESTIGATIONAL NEW DRUG APPLICATION.  After pre-clinical testing, an IND is
filed with the FDA to begin human testing of the drug. The IND becomes effective
if the FDA does not reject it within 30 days. The IND must indicate the results
of previous experiments, how, where and by whom the new studies will be
conducted, how the chemical compound is manufactured, the method by which it is
believed to work in the human body, and any toxic effects of the compound found
in the animal studies. In addition, the IND must be reviewed and approved by an
Institutional Review Board consisting of physicians at the hospital or clinic
where the proposed studies will be conducted. Progress reports detailing the
results of the clinical trials must be submitted at least annually to the FDA.
The Company expects to file two INDs in 1998.
 
    PHASE I CLINICAL TRIALS.  After an IND becomes effective, Phase I human
clinical trials can begin. These studies, involving usually between 20 and 80
healthy volunteers, can take up to one year or more to complete. The studies
determine a drug's safety profile, including the safe dosage range. The Phase I
clinical studies also determine how a drug is absorbed, distributed, metabolized
and excreted by the body, as well as the duration of its action.
 
    PHASE II CLINICAL TRIALS.  In Phase II clinical trials, controlled studies
of approximately 100 to 300 volunteer patients with the targeted disease assess
the drug's effectiveness. These studies are designed primarily to evaluate the
effectiveness of the drug on the volunteer patients as well as to determine if
there are any side effects on these patients. These studies can take up to two
years or more and may be conducted concurrently with Phase I clinical trials. In
addition, Phase I/II clinical trials may be conducted that evaluate not only the
efficacy but also the safety of the drug on the patient population. The Company
anticipates that its Phase I/Phase II clinical trials with Resten-NG and
Cyclosporin-CP will begin in 1998.
 
    PHASE III CLINICAL TRIALS.  This phase typically lasts up to three years or
more and usually involves 1,000 to 3,000 patients with the targeted disease.
During the Phase III clinical trials, physicians monitor the patients to
determine efficacy and to observe and report any adverse reactions that may
result from long-term use of the drug.
 
    NEW DRUG APPLICATION ("NDA").  After the completion of all three clinical
trial phases, the data are analyzed and if the data indicate that the drug is
safe and effective an NDA is filed with the FDA. The NDA must contain all of the
information on the drug that has been gathered to date, including data from the
clinical trials. NDAs are often over 100,000 pages in length. The average NDA
review time for new pharmaceuticals approved in 1995 was approximately 19
months.
 
    FAST TRACK REVIEW.  In December 1992, the FDA formalized procedures for
accelerating the approval of drugs to be marketed for the treatment of certain
serious diseases for which no satisfactory alternative treatment exists, such as
Alzheimer's disease and AIDS. If it is demonstrated that the drug has a positive
effect on survival or irreversible morbidity during Phase II clinical trials,
then the FDA may approve the drug for marketing without completion of Phase III
testing.
 
                                       40

<PAGE>
    APPROVAL.  If the FDA approves the NDA, the drug becomes available for
physicians to prescribe. The Company must continue to submit periodic reports to
the FDA, including descriptions of any adverse reactions reported. For certain
drugs which are administered on a long-term basis, the FDA may request
additional clinical studies (Phase IV) after the drug has begun to be marketed
to evaluate long-term effects.
 
   
    In addition to regulations enforced by the FDA, the Company also is or will
be subject to regulation under the Occupational Safety and Health Act, the
Environmental Protection Act, the Toxic Substances Control Act, the Resource
Conservation and Recovery Act and other present and future federal, state or
local regulations. The Company's research and development activities involve the
controlled use of hazardous materials, chemicals, viruses and various
radioactive compounds. Although the Company believes that its safety procedures
for handling and disposing of such materials comply with the standard prescribed
by state and federal regulations, the risk of accidental contamination or injury
from these materials cannot be completely eliminated. In the event of such an
accident, the Company could be held liable for any damages that result, and any
such liability could exceed the resources of the Company.
    
 
    For marketing outside the United States, the Company or its prospective
licensees will be subject to foreign regulatory requirements governing human
clinical trials and marketing approval for drugs and devices. The requirements
governing the conduct of clinical trials, product licensing, pricing and
reimbursement vary widely from country to country.
 
COMPETITION
 
   
    Several companies are pursuing the development of antisense technology,
including Glaxo, Boehringer Ingelheim, Gilead, Hybridon, ISIS, and Lynx. All of
these companies are in development stages, and, in some cases, are in human
trials with antisense compounds generally similar to the Company's NEU-GENE
compounds. While the Company believes that none of these companies is likely to
introduce an antisense compound into the commercial market in the immediate
future, many pharmaceutical and biotechnology companies, including all of those
listed above, have financial and technical resources greater than those
currently available to the Company and have more established collaborative
relationships with industry partners than does the Company. Lynx has recently
announced that it plans to begin clinical trials with an antisense compound for
restenosis and that it will co-develop this potential application with Schwarz
Pharma AG. The Company believes that the combination of pharmaceutical
properties of its NEU-GENE compounds for restenosis afford it competitive
advantages when compared with the antisense compounds of competitors. Many
companies are pursuing drug delivery technology including Biovail, Cellegy
Pharmaceuticals, Cygnus, and Noven, among others. If the Company's antisense and
drug delivery technologies attain regulatory and commercial acceptance as the
basis for the commercial pharmaceutical products, it is to be expected that
additional companies, including large, multinational pharmaceutical companies,
will choose to compete in the Company's markets, either directly or through
collaborative arrangements.
    
 
                                       41

<PAGE>
    The Company can also expect to compete with other companies exploiting
alternative technologies that address the same therapeutic needs as does the
Company's technology. The biopharmaceutical market is subject to rapid
technological change, and it can be expected that competing technologies will
emerge and will present a competitive challenge to the Company.
 
FACILITIES
 
    The Company occupies 18,400 square feet of leased laboratory and office
space at 4575 S.W. Research Way, Suite 200, Corvallis, Oregon 97333. The
Company's executive office is located in 2,400 square feet of leased space at
One S.W. Columbia, Suite 1105, Portland, Oregon 97258.
 
EMPLOYEES
 
   
    As of December 31, 1996, the Company had 32 employees, 12 of whom hold
advanced degrees. Twenty-seven employees are engaged directly in research and
development activities, and five are in administration. None of the Company's
employees is covered by collective bargaining agreements, and management
considers relations with its employees to be good.
    
 
                           MANAGEMENT OF THE COMPANY
 
DIRECTORS AND EXECUTIVE OFFICERS
 
    The directors and officers of the Company and their ages are as follows:
 

<TABLE>
<CAPTION>
NAME                                     AGE                                   POSITION
- -----------------------------------      ---      -------------------------------------------------------------------
<S>                                  <C>          <C>
John A. Beaulieu(1)(2).............          62   Chairman of the Board
Denis R. Burger, Ph.D.(1)..........          53   Chief Executive Officer, Director
James E. Summerton, Ph.D.(1).......          52   President, Chief Scientific Officer, Director
Alan P. Timmins....................          37   Chief Operating Officer, Chief Financial Officer
Dwight D. Weller, Ph.D.............          46   Vice President of Research and Development, Director
Frederick C. Pearson, Ph.D.........          53   Vice President of Regulatory Affairs and Clinical Development
Nick Bunick........................          60   Director
James B. Hicks, Ph.D...............          50   Director
Donald R. Johnson, Ph.D.(1)........          68   Director
James E. Reinmuth, Ph.D.(2)........          56   Director
Joseph Rubinfeld, Ph.D.(2).........          64   Director
</TABLE>

 
- ------------------------
 
(1) Member of the Executive Committee
 
(2) Member of the Compensation and Audit Committees
 
    JOHN A. BEAULIEU has served as a director at the Company since 1991 and was
elected Chairman in January 1996. He is the Managing Partner of Cascadia Pacific
Management, LLC. ("CPM"). CPM is the contract manager for the Oregon Resource
and Technology Development Fund, a state-funded venture capital fund. Mr.
Beaulieu is also a general partner in Seed Management, a Vancouver B.C.-based
venture capital firm. Mr. Beaulieu is a director of TCC Communications, Biozyme
Inc., Virtual Corp., EPC Inc., and Puriponics LLC. Mr. Beaulieu received his
BS&C degree in Accounting and an M.B.A. from the University of Santa Clara.
 
    DENIS R. BURGER, PH.D. has served as Chief Executive Officer of the Company
since January 1996 and as a director of the Company since 1991. From 1992 to
1995 he was President and Chief Operating Officer of the Company. He co-founded
Epitope, Inc., a biotechnology company, and served as Chairman from 1981 to
1990. Dr. Burger has also been a member of Sovereign Ventures, LLC., a
biotechnology consulting
 
                                       42

<PAGE>
   
and merchant banking venture since 1991. Dr. Burger is a member of the Board of
Directors of Cellegy Pharmaceuticals, Inc., an emerging pharmaceutical company
focused on drug delivery, SuperGen, Inc., a pharmaceutical company focused on
life-threatening diseases, and Trinity Biotech, plc., an Irish diagnostics
company. Dr. Burger held the positions of Assistant Professor, Associate
Professor and Professor at the Oregon Health Sciences University ("OHSU") from
1969 to 1986. Dr. Burger received a B.A. in Bacteriology and Immunology from the
University of California at Berkeley and his M.S. and Ph.D. degrees in
Microbiology and Immunology from the University of Arizona.
    
 
    JAMES E. SUMMERTON, PH.D. has been President and Chief Scientific Officer
since January 1996. He founded the Company in 1980 and was its Chairman and
Chief Executive Officer until January 1996. He held the position of assistant
professor of Biochemistry-Biophysics at Oregon State University from 1978 to
1980. He is the inventor or co-inventor on all of the Company's patents and
pending applications. Dr. Summerton received a B.S. in Chemistry from Northern
Arizona University and a Ph.D. from the University of Arizona. Dr. Summerton
first conceived of the concept of sequence-specific gene-inactivation in 1969.
 
    ALAN P. TIMMINS has served as Chief Operating Officer and Chief Financial
Officer of the Company since October 1996 and Executive Vice President and Chief
Financial Officer since 1992. From 1981 to 1991 he served in a variety of
positions at the firm of Price Waterhouse LLP, most recently as a Senior Manager
specializing in high technology and emerging growth companies. Mr. Timmins
received a B.B.A. in Accounting and Management from the University of Portland
and an M.B.A. from Stanford University. He is a Certified Public Accountant.
 
    DWIGHT D. WELLER, PH.D. has served as Vice President of Research and
Development of the Company since 1992 and as a director of the Company since
1991. He joined the faculty of Oregon State University in 1978 as Assistant
Professor and was an Associate Professor in the Chemistry Department from 1984
to 1992. He is co-inventor on all but one of the Company's issued patents and
patent applications. Dr. Weller received a B.S. in Chemistry from Lafayette
College and a Ph.D. in Chemistry from the University of California at Berkeley,
followed by postdoctoral work in Bio-organic Chemistry at the University of
Illinois.
 
    FREDERICK C. PEARSON, PH.D. has served as Vice President of Regulatory
Affairs and Clinical Development for the Company since March 1997. From 1994 to
1997 he served as Director of Biotechnology for the Colorado Advanced Technology
Institute. During 1992 and 1993 he was Vice President and General Manager of
Greenwich Pharmaceuticals, Inc., and Vice President, Product Development for the
Virus Research Institute. Additionally, he served from 1988 to 1992 as Vice
President, Scientific Affairs for Cell Technology. From 1986 through 1988 he was
Vice President, Renal Therapy Division, Baxter International. Dr. Pearson
received a B.S. in Biology from Nasson College in 1966 and his Ph.D. in
Microbiology/ Virology from the University of New Hampshire in 1972.
 
    NICK BUNICK has served as a director of the Company since 1992. Mr. Bunick
is the President and Chairman of the Board of three real estate development
companies and one investment management company. From 1987 to 1990, he was a
Vice President of In-Focus Systems, Inc., a company that specializes in the
design and manufacturing of flat panel display products. Mr. Bunick received a
B.S. in Business Administration and Marketing from the University of Florida.
 
    JAMES B. HICKS, PH.D. has served as a director of the Company since 1997. He
has served as the Chief Executive Officer, Chief Scientist and a director of
Hedral Therapeutics, Inc., a biotechnology company, since its founding in 1993.
Previously, he was a founding scientist and a Senior Scientific Director at ICOS
Corporation from 1990 to 1993, and Director of the PPG Industries/Scripps Joint
Research Program at Scripps Clinic, as well as an Adjunct Member of the
Molecular Biology Department in the Research Institute of Scripps Clinic from
1986 to 1990. From 1978 through 1986 he was Senior Scientist and Lab Chief of
the Delbruck Laboratory at Cold Spring Harbor Laboratory. Dr. Hicks received his
B.A. degree
 
                                       43

<PAGE>
in Biology from Willamette University and his Ph.D. in Molecular Biology from
the University of Oregon, followed by post-doctoral research at Cornell
University.
 
   
    DONALD R. JOHNSON, PH.D. has served as a director of the Company since 1991.
He founded Technology Conversion, a research and new product development
consulting firm in 1986, and has served as its President since that time. Dr.
Johnson was Director, New Technology Research, Diagnostic and Bioresearch
Products at E. I. du Pont de Nemours and Company, Inc., from 1983 to 1986. Dr.
Johnson received a B.A. in Chemistry from the University of Minnesota and a
Ph.D. in Analytical Chemistry from the University of Wisconsin.
    
 
    JAMES E. REINMUTH, PH.D. has served as a director of the Company since 1991.
He was Dean of the College of Business Administration at the University of
Oregon from 1976 to 1994 and since 1995 has been the Charles H. Lundquist
Distinguished Professor of Business at University of Oregon. Dr. Reinmuth is the
Chairman of the Board of Directors and Chief Executive Officer of Athena Medical
Corp., a feminine health care company. He is also the President and Chief
Executive Officer of Fuji Advanced Filtration, Inc. Dr. Reinmuth is a general
partner in Rubicon Asset Management Corp. Dr. Reinmuth received a B.S. in
Mathematics from the University of Washington and his M.S. and Ph.D. degrees in
Statistics from Oregon State University.
 
    JOSEPH RUBINFELD, PH.D. has been a director of the Company since 1996. He
has served as Chief Executive Officer, President, Chief Scientific Officer and a
director of SuperGen, Inc. since its inception in 1992. Dr. Rubinfeld was one of
the four initial founders of Amgen Inc. in 1980 and served as Vice President and
Chief of Operations until 1983. From 1987 to 1990, he was Senior Director at
Cetus Corporation. From 1968 to 1980, Dr. Rubinfeld was employed at
Bristol-Myers Squibb (formerly Bristol-Myers International Corporation) in a
variety of positions, most recently as Vice President and Director of Research
and Development. He received his B.S. in Chemistry from C.C.N.Y., and his M.A.
and Ph.D. degrees in Chemistry from Columbia University.
 
DIRECTOR COMPENSATION
 
    Directors who are not employees of the Company receive a non-qualified
option to purchase 33,333 shares of Common Stock at an exercise price equal to
the fair market value of the Common Stock on the date of the grant pursuant to
the Company's Stock Incentive Plan, which vests over four years. See "Stock
Incentive Plan." Drs. Johnson and Rubinfeld are reimbursed for expenses for
attendance at board meetings.
 
SCIENTIFIC ADVISORY COMMITTEE
 
    The Company has established relationships with a group of scientific
advisors with expertise in their respective fields that complement the Company's
product research and development. The following individuals serve on the
Scientific Advisory Committee to the Company's Board of Directors:
 
    CHRISTOPHER K. MATHEWS, PH.D. is Chairman of the Scientific Advisory
Committee. He is the Chairman of the Biochemistry-Biophysics Department at
Oregon State University. Dr. Mathews received a B.A. from Reed College and a
Ph.D. in Biochemistry from the University of Washington. He performed
postdoctoral work in Biochemistry at the University of Pennsylvania. Dr. Mathews
joined the Scientific Advisory Committee in 1994 and was a director of the
Company from 1991 to 1994.
 
    STEVEN H. HEFENEIDER, PH.D. has been a staff immunologist at the Veterans
Administration Medical Center in Portland, Oregon since 1985 and Research
Associate Professor in the Department of Medicine at Oregon Health Sciences
University ("OHSU") since 1987. He received a B.S. in biology from the
University of Oregon, an M.S. in genetics from the University of Minnesota and a
Ph.D. in Microbiology and Immunology from OHSU in 1981.
 
                                       44

<PAGE>
    DAVID J. HINRICHS, PH.D. is a Research Scientist at the Veterans
Administration Medical Center in Portland, Oregon and a Professor of
Microbiology and Immunology at OHSU. From 1976 to 1985 he was a Professor of
Microbiology at Washington State University. He received a Ph.D. in Microbiology
from the University of Arizona in 1967.
 
    JEFFREY D. HOSENPUD, M.D. has been Chief of Cardiology and a Professor of
Medicine at the Medical College of Wisconsin in Milwaukee since 1994. Dr.
Hosenpud was Professor of Medicine and Head of the Cardiac Transplant Medicine
at OHSU from 1980 to 1994, and Medical Director for the Registry of the
International Society for Heart & Lung Transplantation since 1993. Dr. Hosenpud
competed his M.D. at the University of California, Los Angeles.
 
EXECUTIVE COMPENSATION
 
   
    SUMMARY COMPENSATION TABLE.  The following table sets forth, for the fiscal
year ended December 31, 1996, certain summary information concerning
compensation of the persons serving as the Company's Chief Executive Officer
(the "Named Officers"). No other executive officer received compensation
exceeding $100,000.
    
 
                           SUMMARY COMPENSATION TABLE
 

<TABLE>
<CAPTION>
                                                                                        LONG-TERM
                                                                                      COMPENSATION
                                                                                     ---------------
                                                                1996 COMPENSATION      SECURITIES
                                                              ---------------------    UNDERLYING         ALL OTHER
                                                                SALARY      BONUS        OPTIONS       COMPENSATION(1)
                                                              ----------  ---------  ---------------  -----------------
<S>                                                           <C>         <C>        <C>              <C>
Denis R. Burger, Ph.D.......................................  $  121,925                                      2,443
  Chief Executive Officer
James E. Summerton, Ph.D....................................  $   92,483     --            --                 2,712
  President and Chief Scientific Officer(2)
</TABLE>

 
- ------------------------
 
(1) Represents matching amounts received under the Company's 401(k) plan.
 
(2) Dr. Summerton resigned as the Chairman and Chief Executive Officer in
    January 1996 and is now the Company's President and Chief Scientific
    Officer.
 
                   AGGREGATE OPTION EXERCISES IN LAST FISCAL
                     YEAR AND FISCAL YEAR-END OPTION VALUES
 
    The following table sets forth information concerning the value of
unexercised options as of December 31, 1996, held by the Named Officer. No
options were exercised by the Named Officer during the year ended December 31,
1995.
 

<TABLE>
<CAPTION>
                                                               NUMBER OF SECURITIES        VALUE OF UNEXERCISED
                                                                    UNDERLYING             IN-THE-MONEY OPTIONS
                                                              UNEXERCISED OPTIONS AT       AT DECEMBER 31, 1996
                                                              DECEMBER 31, 1996 (#)               ($)(1)
                                                            --------------------------  --------------------------
NAME                                                        EXERCISABLE  UNEXERCISABLE  EXERCISABLE  UNEXERCISABLE
- ----------------------------------------------------------  -----------  -------------  -----------  -------------
<S>                                                         <C>          <C>            <C>          <C>
Denis R. Burger, Ph.D.....................................     365,735        --           520,487        --
James Summerton, Ph.D.(2).................................     132,220        93,334       144,502        125,418
</TABLE>

 
- ------------------------
 
(1) Based upon the difference between the fair market value of the securities
    underlying the options at December 31, 1996 ($6.00 per share as determined
    by the Board of Directors) and the exercise price of the options.
 
                                       45

<PAGE>
(2) Dr. Summerton resigned as the Chairman and Chief Executive Officer in
    January 1996 and is now the Company's President and Chief Scientific
    Officer.
 
EMPLOYMENT AGREEMENTS
 
    The Company has entered into employment contracts with Messrs. Burger and
Summerton that provide for annual base salaries for Drs. Burger and Summerton of
$120,000 and $90,000, respectively, that increase to $225,000 and $150,000,
respectively, on January 1, 1997. The employment agreements also provide for the
payment to Drs. Burger and Summerton of one additional year of base salary and
the immediate and full vesting of all options granted to them under the
Company's stock incentive plan in the event of the termination of their
respective employment for reasons, other than cause, or upon their voluntary
termination upon a change in control of the Company. In addition, the employment
agreements prevent Drs. Burger and Summerton from competing with the Company for
a period of two years following termination of their employment for any reason.
Dr. Summerton's agreement also provides that the Company shall engage him as a
consultant for a term of one year following the termination of his employment at
the rate of $75,000 per year and grants the Company the option to engage him as
a consultant on the same terms for a second year. Drs. Burger and Summerton are
deferring their January 1, 1997, salary increases until completion of the
Company's initial public offering.
 
STOCK INCENTIVE PLAN
 
    The Stock Incentive Plan was adopted by the Board of Directors and was
approved by the shareholders in 1992. The purposes of the Stock Incentive Plan
are to attract and retain the best available personnel for positions of
substantial responsibility, to provide additional incentive to the employees and
consultants of the Company and to promote the success of the Company's business.
 
   
    The Stock Incentive Plan is administered by the Compensation Committee (the
"Committee"). Transactions under the Stock Incentive Plan are intended to comply
with all applicable conditions of Rule 16b-3 promulgated under the Securities
Exchange Act of 1934. In addition to determining who will be granted options,
the Committee has the authority and discretion to determine when options will be
granted and the number of options to be granted. The Committee may determine
which options may be intended to qualify ("Incentive Stock Options") for special
treatment under the Internal Revenue Code of 1986, as amended from time to time
(the "Code"), or whether options are non-qualified options ("Non-Qualified Stock
Options") which are not intended to so qualify. The Committee also may determine
the time or times when each option becomes exercisable, the duration of the
exercise period for options and the form or forms of the instruments evidencing
options granted under the Stock Incentive Plan. The Committee may adopt, amend
and rescind such rules and regulations as in its opinion may be advisable for
the administration of the Stock Incentive Plan. The Committee also may construe
the Stock Incentive Plan and the provisions in the instruments evidencing option
granted under Stock Incentive Plan to employee and officer participants and is
empowered to make all other determinations deemed necessary or advisable for the
administration of the Stock Incentive Plan. SARs and stock bonuses may also be
granted under the Stock Incentive Plan.
    
 
    The Stock Incentive Plan contains provisions for proportionate adjustment of
the number of shares for outstanding options and the option price per share in
the event of stock dividends, recapitalizations resulting in stock splits or
combinations or exchanges of shares. In addition, the Stock Incentive Plan
provides for adjustments in the purchase price and exercise period by the
Committee in the event of a proposed dissolution or liquidation of the Company,
or any corporate separation or division, including, but not limited to,
split-up, split-off or spin-off, or a merger or consolidation of the Company
with another corporation, or in the event there is a change in constitution of
the Common Stock of the Company.
 
    Participants in the Stock Incentive Plan may be selected by the Committee
from employees, officers, directors and consultants of the Company. In
determining the persons to whom options will be granted and
 
                                       46

<PAGE>
the number of shares to be covered by each option, the Committee will take into
account the duties of the respective persons, their present and potential
contributions to the success of the Company and such other factors as the
Committee deems relevant to accomplish the purposes of the Stock Incentive Plan.
 
    Only employees of the Company as the term "employees" is defined for the
purposes of Code will be entitled to receive Incentive Stock Options. Incentive
Stock Options granted under the Stock Incentive Plan are intended to satisfy all
requirements for incentive stock options under Section 422 of the Code and the
Treasury Regulations thereunder.
 
    Each option granted under the Stock Incentive Plan will be evidenced by a
written option agreement between the Company and the optionee. The option price
of any Incentive Stock Option may be not less than 100% of the fair market value
per share on the date of grant of the option; provided, however, that any
Incentive Stock Option granted under the Stock Incentive Plan to a person owning
more than 10% of the total combined voting power of the Common Stock will have
an option price of not less than 110% of the fair market value per share on the
date of grant of the Incentive Stock Option. Each Non-Qualified Stock Option
granted under the Stock Incentive Plan will be at an exercise price as
determined by the Board of Directors. Fair market value on the date of grant is
defined as a value determined in the discretion of the Board; provided, however,
that where there is a public market for the Common Stock, the fair market value
per share shall be the closing price of the Common Stock for the date of grant
or authorization of sale, as reported in THE WALL STREET JOURNAL.
 
    The exercise period of Incentive Stock Options granted under the Stock
Incentive Plan generally may not exceed 10 years from the date of grant thereof.
Incentive Stock Options granted to a person owning more than 10 percent of the
total combined voting power of the Common Stock of the Company will be for no
more than five years. The Committee will have the authority to accelerate or
extend the exercisability of any outstanding option at such time and under such
circumstances as it, in its sole discretion, deems appropriate. However, no
exercise period may be extended to increase the term of an Incentive Stock
Option beyond 10 years from the date of grant.
 
    To exercise an option, the optionee must pay the full exercise price in
whole or in part consisting of cash or transfer to the Company of shares having
a fair market value at the time of such exercise equal to the option exercise
price.
 
    An option may not be exercised unless the optionee then is an employee,
officer, director or consultant of the Company, and unless the optionee has
remained continuously as an employee, officer, director or consultant of the
Company since the date of grant of the option. If the optionee ceases to be an
employee, officer, director or consultant of the Company, all options which are
not vested under the Stock Incentive Plan by the time of death, disability,
retirement or termination of employment, immediately terminate. All options
granted to such optionee that are fully vested to such optionee but not yet
exercised, will terminate (i) 12 months after the date the optionee ceases to be
an employee, officer or director of the Company by reason of death or
disability; or (ii) 30 days after termination of employment for any other
reason.
 
    If an optionee dies while an employee, officer, director or consultant, or
is terminated by reason of disability, all options theretofore granted to such
optionee, unless earlier terminated in accordance with their terms, may be
exercised at any time within one year after the date of death or disability of
said optionee, by the optionee or by the optionee's estate or by a person who
acquired the right to exercise such options by request or inheritance, but only
to the extent of the right to exercise as of the date of death or disability.
 
    Options granted under the Stock Incentive Plan are not transferable other
than by will or by the laws of descent and distribution. Options may be
exercised during the lifetime of the optionee only by the optionee. An optionee
has no rights as a shareholder with respect to any shares covered by an option
until the option has been exercised.
 
                                       47

<PAGE>
    The Company, to the extent permitted by law, may deduct a sufficient number
of shares due to the optionee upon exercise of the option to allow the Company
to pay federal, state and local taxes of any kind required by law to be withheld
upon the exercise otherwise due to the optionee. The Company is not obligated to
advise any optionee of the existence of any tax or the amount which the Company
will be required to withhold.
 
    As of the date of this Prospectus, options to purchase 1,126,886 shares of
the Company's Common Stock have been granted and are outstanding under the Stock
Incentive Plan, at a weighted average exercise price of $4.73 per share, and
206,447 shares were available for future grants.
 
LIMITATION OF LIABILITY AND INDEMNIFICATION
 
    The Company's Third Restated Articles of Incorporation eliminate, to the
fullest extent permitted by Oregon law, liability of a director to the Company
or its shareholders for monetary damages for conduct as a director. While
liability for monetary damages has been eliminated, equitable remedies such as
injunctive relief or rescission remain available. In addition, a director is not
relieved of his or her responsibilities under any other law, including the
federal securities laws.
 
    The Company's Third Restated Articles of Incorporation require the Company
to indemnify its directors to the fullest extent not prohibited by law. The
Oregon Business Corporation Act authorizes a corporation, through its articles
of incorporation and bylaws, to limit the liability of directors and to grant
indemnity to directors, officers, employees or agents for actions taken with
respect to corporation in their respective capacities as directors, officers,
employees or agents. Indemnification for such liabilities may be provided to an
officer, director, employee or agent based upon the determination by a vote of
the disinterested Board of Directors, a vote by a special committee of the Board
of Directors, by the determination of a special legal counsel or by a vote of
the shareholders that the director, officer, employee or agent may properly be
indemnified under the statute. The Company believes that the limitation of
liability provisions in its Third Restated Articles may enhance the Company's
ability to attract and retain qualified individuals to serve as directors.
 
    Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the Company
pursuant to the foregoing provisions or otherwise, the Company has been advised
that in the opinion of the Securities and Exchange Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Company of expenses
incurred or paid by a director, officer or controlling person of the Company in
the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Company will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question of whether such indemnification by it is against
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.
 
                  CERTAIN TRANSACTIONS OF THE COMPANY AND AGDG
 
    James E. Summerton, Ph.D., the President, Chief Scientific Officer, and a
director of the Company, is the general partner of Anti-Gene Development Group
("AGDG"), and was the general partner of NEU-GENE Development Group ("NGDG").
AGDG was founded in 1981 and NGDG was founded in 1984 to own and fund the
Company's development of gene-targeted therapeutics and NEU-GENE technology.
NGDG and AGDG were combined in 1989, with AGDG as the surviving entity. The
Company entered into numerous research and development contracts with AGDG and
NGDG, all of which were completed or were superseded by the Technology Transfer
Agreement described below.
 
    On February 9, 1993, the Company and AGDG entered into a Technology Transfer
Agreement wherein effective May 19, 1993, AGDG conveyed all intellectual
property in its control related to antisense
 
                                       48

<PAGE>
technology (the "Intellectual Property") to the Company. As part of the
conveyance, the Company tendered to AGDG for liquidation all partnership units
received pursuant to an exchange offer and received a 49.37 percent undivided
interest in the intellectual property. The Company then purchased the remaining
undivided interest in the Intellectual Property in consideration of payments of
4.05% of gross revenues in excess of $200 million, if any, sales of products by
the Company which would, in the absence of the Technology Transfer Agreement,
infringe a valid claim under any patent transferred to the Company (the
"Technology Fees"). The Company's obligation to make payments of the Technology
Fees with respect to a particular product terminates upon the expiration of all
patents transferred to the Company pursuant to the Technology Transfer Agreement
related to that product.
 
    Pursuant to a License and Option Agreement by and between AGDG and the
Company dated February 9, 1993 (the "License Agreement"), the Company granted to
AGDG a royalty-free non-exclusive license to use the Intellectual Property for
internal research and development and to sell small quantities of products
incorporating the Intellectual Property. In addition, if AGDG develops any
specific prototype products which incorporate any of the Intellectual Property,
the Company has the right to commercialize and market such products in
consideration of payments of 4.05% of gross revenues, in excess of the $200
million exemption for all products utilizing the Intellectual Property, to AGDG.
If the Company elects not to commercialize the proposed AGDG product or fails to
meet certain product development milestones, the Company is required to grant
AGDG a license to develop and market the proposed product (an "AGDG License").
The Company is entitled to payments for the AGDG license but only if the
proposed product incorporates patented improvements developed by the Company to
the Intellectual Property. The amount of the license fee payable to the Company
by AGDG pursuant to an AGDG License, if any, is equal to the percentage payable
to AGDG for products sold by the Company and covered by the Technology Transfer
Agreement. AGDG also has the right to obtain an exclusive royalty-free license
to use, develop, make, sell, distribute and sublicense products utilizing the
Intellectual Property at such time as the Company has less than 10 full-time
employees engaged in developing, testing or marketing products based upon the
Intellectual Property for a period of at least 180 consecutive days.
 
    On January 20, 1997, AGDG and the Company amended the Technology Transfer
Agreement to reduce the Technology Fees arising from the sale of diagnostic
products from 4.05% to 2% and to remove the $200 million exemption with respect
to sales of such diagnostic products. The Company also granted to AGDG a
royalty-bearing license to make, use and sell certain quantities of product
derived from the Intellectual Property.
 
    The Company's Board of Directors has required, in conformity with Oregon
law, that a transaction in which a director has a conflict of interest be
approved by a majority of disinterested directors. The Board has recognized that
Dr. Summerton has a direct or indirect conflict of interest in connection with
transactions between the Company and AGDG and, in such circumstances, the terms
and conditions of such transactions have been negotiated for the Company by
officers other than Dr. Summerton and have been approved by a majority of
disinterested directors after disclosure of the conflict of interest.
 
    Pursuant to an August 4, 1992 restatement of earlier agreements between
Oregon Resource and Technology Development Fund ("ORTDF"), the Company, AGDG and
Dr. Summerton, warrants to purchase 600,000 shares of the Company's Common Stock
have been issued to ORTDF. John A. Beaulieu was president of ORTDF and a
director of the Company at that time. In connection with this issuance to ORTDF,
they acquired certain rights to register such shares under the Securities Act.
See "Description of Securities--Registration Rights." In May 1993, ORTDF
acquired warrants to purchase an additional 357,500 shares in exchange for 325
partnership units in AGDG conveyed to the Company. Such warrants carry no
registration rights. In March 1996, ORTDF exercised its warrants in a cashless
exercise for which ORTDF acquired 957,452 shares of the Company's Common Stock.
 
                                       49

<PAGE>
   
                             PRINCIPAL SHAREHOLDERS
    
 
   
    The following table sets forth certain information with respect to the
beneficial ownership of the Company's Common Stock as of April 11, 1997, and as
adjusted to give effect to the sale by the Company of the shares of Common Stock
offered pursuant to its Unit Offering (assuming no exercise of the Overallotment
Option or the Warrants) by (i) each person (or group of affiliated persons) who
is known by the Company to own beneficially 5% or more of the Common Stock, (ii)
each of the Company's directors, (iii) the Named Officer, and (iv) all executive
officers and directors of the Company as a group. The information as to each
person or entity has been furnished by such person or entity, and unless
otherwise indicated, the persons named in the table have sole voting and sole
investment power with respect to all shares beneficially owned, subject to
community property laws where applicable.
    
 
   

<TABLE>
<CAPTION>
                                                                                                PERCENT OF SHARES
                                                                                                   OUTSTANDING
                                                                                  SHARES     ------------------------
                                                                                BENEFICIALLY BEFORE UNIT  AFTER UNIT
NAME AND ADDRESS OF BENEFICIAL OWNER(1)                                          OWNED(1)     OFFERING    OFFERING(1)
- ------------------------------------------------------------------------------  -----------  -----------  -----------
<S>                                                                             <C>          <C>          <C>
 
James E. Summerton, Ph.D.(2)..................................................   2,553,473        24.8%        21.6%
  ANTIVIRALS Inc.
  4575 S.W. Research Way, Suite 200
  Corvallis, OR 97333
 
John A. Beaulieu(3)...........................................................     990,785         9.7%         8.5%
  4370 N.E. Halsey, Suite 233
  Portland, OR 97213
 
Oregon Resource and Technology................................................     990,785         9.7%         8.5%
  Development Fund(4)
  4370 N.E. Halsey, Suite 233
  Portland, OR 97213
 
Wayne Embree(5)...............................................................     957,452         9.4%         8.2%
  4370 N.E. Halsey, Suite 233
  Portland, OR 97213
 
Denis R. Burger, Ph.D.(6).....................................................     406,886         3.9%         3.4%
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
Dwight D. Weller, Ph.D.(7)....................................................     370,178         3.6%         3.1%
  ANTIVIRALS Inc.
  4575 S.W. Research Way, Suite 200
  Corvallis, OR 97333
 
Nick Bunick(8)................................................................     200,733         2.0%         1.7%
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
Alan P. Timmins(9)............................................................      68,825        *            *
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
</TABLE>

    
 
                                       50

<PAGE>

<TABLE>
<CAPTION>
                                                                                                PERCENT OF SHARES
                                                                                                   OUTSTANDING
                                                                                  SHARES     ------------------------
                                                                                BENEFICIALLY BEFORE UNIT  AFTER UNIT
NAME AND ADDRESS OF BENEFICIAL OWNER(1)                                          OWNED(1)     OFFERING    OFFERING(1)
- ------------------------------------------------------------------------------  -----------  -----------  -----------
<S>                                                                             <C>          <C>          <C>
Donald R. Johnson, Ph.D.(10)..................................................      64,333        *            *
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
James E. Reinmuth, Ph.D.(11)..................................................      51,817        *            *
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
Joseph Rubinfeld, Ph.D.(12)...................................................       8,334        *            *
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
James B. Hicks, Ph.D..........................................................           0        *            *
  ANTIVIRALS Inc.
  1 S.W. Columbia, Suite 1105
  Portland, OR 97258
 
Frederick C. Pearson, Ph.D....................................................           0        *            *
  ANTIVIRALS Inc.
  4575 S.W. Research Way, Suite 200
  Corvallis, OR 97333
 
All executive officers and directors as a group(10 persons)...................   4,715,365        53.7%        45.9%
</TABLE>

 
- ------------------------
 
*   Less than 1%.
 
   
 (1) Beneficial ownership is determined in accordance with the rules of the
    Securities and Exchange Commission and generally includes voting or
    investment power with respect to securities. Shares of Common Stock subject
    to options and warrants currently exercisable or convertible, or exercisable
    or convertible within 60 days of April 11, 1997, are deemed beneficially
    owned and outstanding for computing the percentage of the person holding
    such securities, but are not considered outstanding for computing the
    percentage of any other person.
    
 
   
 (2) Includes 158,886 shares subject to options exercisable within 60 days as of
    April 11, 1997, and 727,154 shares held jointly or by others over which Dr.
    Summerton exercises voting and investment power. Does not include 66,667
    shares subject to options exercisable after April 11, 1997.
    
 
   
 (3) Includes 33,334 shares subject to options exercisable within 60 days as of
    April 11, 1997, of which Mr. Beaulieu is the record owner. ORTDF is the
    beneficial owner of all of the 33,334 options for which Mr. Beaulieu is the
    record owner. Includes 957,452 shares of common stock issued to Cascadia
    Pacific Management, LLC for the benefit of ORTDF.
    
 
   
 (4) Includes 33,334 shares subject to options held of record by Mr. Beaulieu
    and exercisable within 60 days as of April 11, 1997 and 957,942 shares
    issued to Cascadia Pacific Managment, LLC for the benefit of ORTDF. See Note
    3 above.
    
 
 (5) Includes 957,452 shares of Common Stock issued to Cascadia Pacific
    Management, LLC for the benefit of ORTDF.
 
                                       51

<PAGE>
   
 (6) Includes 34,434 shares held by Sovereign Ventures, LLC, a limited liability
    company in which Dr. Burger is a general partner. Also includes 365,735
    shares subject to options exercisable within 60 days as of April 11, 1997.
    
 
   
 (7) Includes 247,634 shares held jointly or by others over which Dr. Weller
    exercises voting and investment power, 94,018 shares subject to options
    exercisable by Dr. Weller and 1,860 shares subject to options exercisable by
    Dr. Weller's spouse as of April 11, 1997, and 25,000 shares subject to
    warrants exercisable within 60 days as of April 11, 1997. Does not include
    25,000 shares subject to warrants exercisable after June 10, 1997.
    
 
   
 (8) Includes 50,667 shares held jointly or by others over which Mr. Bunick
    exercises voting and investment power. Includes 33,334 shares subject to
    options exercisable within 60 days as of April 11, 1997.
    
 
   
 (9) Includes 68,825 shares subject to options exercisable within 60 days as of
    April 11, 1997. Does not include 38,333 shares subject to options
    exercisable after June 10, 1997.
    
 
   
(10) Includes 33,334 shares subject to options and 16,667 shares subject to
    warrants exercisable within 60 days as of April 11, 1997.
    
 
   
(11) Includes 33,334 shares subject to options exercisable within 60 days as of
    April 11, 1997. Also includes 5,051 shares held jointly with others over
    which Dr. Reinmuth exercises voting and investment power.
    
 
   
(12) Includes 8,334 shares subject to options exercisable within 60 days as of
    April 11, 1997. Does not include 25,000 shares subject to options
    exercisable after June 10, 1997.
    
 
                                       52

<PAGE>
                    DESCRIPTION OF SECURITIES OF THE COMPANY
 
    The authorized capital stock of the Company consists of 50,000,000 shares of
Common Stock and 2,000,000 shares of Preferred Stock.
 
COMMON STOCK
 
   
    The Company is authorized to issue 50,000,000 shares of Common Stock. As of
March 31, 1997, 8,779,763 shares of Common Stock were outstanding, held of
record by 881 shareholders. The Company anticipates that 10,279,763 shares of
its Common Stock will be outstanding if the Unit Offering is completed. The
holders of Common Stock are entitled to one vote for each share held of record
on all matters submitted to a vote of shareholders (and do not have any
cumulative voting rights). Subject to preferences that may be applicable to
outstanding shares of Preferred Stock, if any, the holders of Common Stock are
entitled to receive ratably such dividends as may be declared by the Company's
Board of Directors out of funds legally available therefor. Holders of Common
Stock have no preemptive, subscription or redemption rights, and there are no
redemption, conversion or similar rights with respect to such shares. In the
event of a liquidation, dissolution or winding up of the Company, holders of the
Common Stock are entitled to share equally and ratably in the assets of the
Company, if any, remaining after the payment of all liabilities of the Company
and the liquidation preference of any outstanding class or series of Preferred
Stock. The outstanding shares of Common Stock are fully paid and nonassessable.
The rights, preferences and privileges of holders of Common Stock are subject to
any series of Preferred Stock that the Company may issue in the future, as
described below.
    
 
PREFERRED STOCK
 
    The Company is authorized to issue up to 2,000,000 shares of undesignated
Preferred Stock. No shares of Preferred Stock have been issued. The Board of
Directors has the authority to issue the undesignated Preferred Stock in one or
more series and to fix the rights, preferences, privileges and restrictions
granted to or imposed upon any wholly unissued shares of undesignated Preferred
Stock, as well as to fix the number of shares constituting any series and the
designation of such series, without any further vote or action by the
shareholders. The Board of Directors, without shareholder approval, may issue
Preferred Stock with voting and conversion rights which could materially
adversely affect the voting power of the holders of Common Stock. The issuance
of Preferred Stock could also decrease the amount of earnings and assets
available for distribution to holders of Common Stock. In addition, the issuance
of Preferred Stock may have the effect of delaying, deferring or preventing a
change in control of the Company. At present, the Company has no plans to issue
any shares of Preferred Stock. See "Risk Factors--Anti-Takeover Effects of
Certain Charter Provisions and Oregon Law" and "Certain Provisions of the
Company's Articles of Incorporation and Bylaws."
 
WARRANTS
 
   
    REPRESENTATIVES' WARRANTS.  In connection with its Unit Offering, the
Company has authorized the issuance of the Representatives' Warrants and has
reserved 300,000 shares of Common Stock for issuance upon exercise of such
warrant (including the warrants issuable upon exercise of the Representatives'
Warrants). The Representatives' Warrants will entitle the holder to acquire up
to an aggregate of 150,000 Units at an exercise price of $      per Unit (120%
of the initial public offering price for the Units). The Representatives'
Warrants will be exercisable at any time from the first anniversary of the date
of the Unit Offering Prospectus until the fifth anniversary of the date of the
Unit Offering Prospectus.
    
 
   
    THE WARRANTS.  In connection with its Unit Offering, the Company will issue
1,500,000 warrants (the "Warrants"). Each Warrant will entitle the holder to
purchase one share of Common Stock at a price of $      per share (150% of the
initial public offering price for the Units). The Warrants will, subject to
certain conditions, be exercisable at any time until the fifth anniversary of
the date of the Unit Offering
    
 
                                       53

<PAGE>
Prospectus, unless earlier redeemed. The Warrants are redeemable by the Company
at $.25 per Warrant, upon 30 days written notice, if the closing bid price (as
defined in the Warrant Agreement described below) per share of the Common Stock
for each of the 20 consecutive trading days immediately preceding the date
notice of redemption is given equals or exceeds 200% of the then-current Warrant
exercise price. If the Company gives notice of its intention to redeem, a holder
would be forced either to exercise his or her Warrant before the date specified
in the redemption notice or accept the redemption price.
 
   
    The Warrants will be issued in registered form under a Warrant Agreement
(the "Warrant Agreement") between the Company and ChaseMellon Shareholder
Services, as warrant agent (the "Warrant Agent"). The shares of Common Stock
underlying the Warrants, when issued upon exercise of a Warrant, will be fully
paid and nonassessable, and the Company will pay any transfer tax incurred as a
result of the issuance of Common Stock to the holder upon its exercise.
    
 
   
    The Warrants and the Representatives' Warrants contain provisions that
protect the holders against dilution by adjustment of the number of shares that
may be purchased by the holders. Such adjustments will occur in the event, among
others, that the Company makes certain distributions to holders of its Common
Stock. The Company is not required to issue fractional shares upon the exercise
of a Warrant or Representatives' Warrants. The holder of a Warrant or
Representatives' Warrants will not possess any rights as a shareholder of the
Company until such holder exercises the Warrant or Representatives' Warrants.
    
 
    A Warrant may be exercised upon surrender of the Warrant Certificate on or
before the expiration date of the Warrant at the offices of the Warrant Agent,
with the form of "Election To Purchase" on the reverse side of the Warrant
Certificate completed and executed as indicated, accompanied by payment of the
exercise price (by certified or bank check payable to the order of the Company
or by wire transfer of good funds) for the number of shares with respect to
which the Warrant is being exercised.
 
    For a holder to exercise the Warrants, there must be a current registration
statement in effect with the Commission and qualification in effect under
applicable state securities laws (or applicable exemptions from state
qualification requirements) with respect to the issuance of shares or other
securities underlying the Warrants. The Company has agreed to use all
commercially reasonable efforts to cause a registration statement with respect
to such securities under the Securities Act to be filed and to become and remain
effective in anticipation of and prior to the exercise of the Warrants and to
take such other actions under the laws of various states as may be required to
cause the sale of Common Stock (or other securities) issuable upon exercise of
Warrants to be lawful. If a current registration statement is not in effect at
the time a Warrant is exercised, the Company may at its option redeem the
Warrant by paying to the holder cash equal to the difference between the market
price of the Common Stock on the exercise date and the exercise price of the
Warrant. The Company will not be required to honor the exercise of Warrants if,
in the opinion of the Company's Board of Directors upon advice of counsel, the
sale of securities upon exercise would be unlawful.
 
   
    The foregoing discussion of certain terms and provisions of the Warrants and
Representatives' Warrants is qualified in its entirety by reference to the
detailed provisions of the Warrant Agreement and Representatives' Warrants
Certificate, the form of each of which has been filed as an exhibit to the
Registration Statement filed in connection with the Unit Offering.
    
 
   
    For the life of the Warrants and Representatives' Warrants, the holders
thereof have the opportunity to profit from a rise in the market price of the
Common Stock without assuming the risk of ownership of the shares of Common
Stock issuable upon the exercise of the warrants. The warrant holders may be
expected to exercise their warrants at a time when the Company would, in all
likelihood, be able to obtain any needed capital by an offering of Common Stock
on terms more favorable than those provided for by the warrants. Further, the
terms on which the Company could obtain additional capital during the life of
the warrants may be adversely affected.
    
 
                                       54

<PAGE>
    OTHER WARRANTS.  The Company has outstanding warrants to purchase 147,899
shares of Common Stock, of which warrants to purchase 25,000 shares are not
presently exercisable. Of these warrants, 38,001 are exercisable through the
period ending 90 days after the expiration of lock-up agreements entered into in
connection with this offering, of which 27,001 are exercisable at a price of
$0.0003 per share and 11,000 are exercisable at a price of $1.14 per share.
Warrants to purchase 14,467 shares are exercisable through July 17, 1997, at an
exercise price of $0.0003 per share. Warrants to purchase 25,000 shares are
exercisable through December 31, 1997, at an exercise price of $0.0003 per
share. Warrants to purchase 1,100 shares are exercisable through August 8, 2001,
at an exercise price of $4.56 per share. Warrants to purchase 44,334 shares are
currently exercisable and do not have a termination date; warrants to purchase
11,000 of these shares are exercisable at a price of $1.14 per share and
warrants to purchase 33,334 of these shares are exercisable at $0.0003 per
share.
 
    The Company also has outstanding a warrant to purchase 219,334 shares of
Common Stock, exercisable through the earlier of the closing of a firmly
underwritten public offering by the Company with proceeds exceeding $5,000,000
or May 14, 2002, at an exercise price of $6.00 per share, which price is subject
to adjustment to prevent dilution. The exercise is also subject to a fair market
value adjustment to make the price paid by the warrant holder equivalent to the
price paid by certain independent third-party purchasers. For purposes of this
adjustment, an independent third-party purchaser is any party who purchases
shares of the Company's Common Stock for not less than $250,000, who was not a
shareholder of the Company on May 1, 1992, and who is not an affiliate, officer
or director of the Company. The Company has agreed to register the shares
underlying this warrant under certain circumstances. See "Registration Rights."
 
    The Company additionally has outstanding warrants to purchase 60,201 shares
of Common Stock at an exercise price of $ 9.00 per share. These warrants are
exercisable through the earlier of August 30, 2001 or three years from the date
of closing by the Company of an initial public offering.
 
THE RESCISSION NOTES
 
    In the event that the Company's liability under the Rescission Offer exceeds
$1.5 million, the Company will issue on a pro rata basis to Eligible Offerees
who accept the Rescission Offer unsecured promissory notes bearing interest at
9% per annum. Interest will be payable quarterly and principal will be due and
payable only at maturity. The terms of the promissory notes will range from 18
to 36 months. There is no sinking fund and holders of the notes will have no
right to convert them into other securities of the Company or to have the
Company redeem the notes.
 
    Payment by the Company of its obligations under the Notes will be secured by
a pledge of shares of the Common Stock of the Company held of record by certain
of the Company's directors and executive officer (the "Pledgors"). Under the
terms of the Pledge Agreement, prior to the closing of the Company's proposed
offering of 1,500,000 units, the Pledgors have agreed to maintain as security
for payment of the Notes sufficient shares of Common Stock of the Company that
the aggregate value of such shares, based on an estimated value of $6.00 per
share, equals 120 percent of the outstanding principal amount of the Notes.
After the closing of the proposed unit offering or any other public offering,
the Pledgors have agreed to maintain as security for payment of the Notes
sufficient shares of Common Stock of the Company that the aggregate value of
such shares, based on the last reported sales price of the Company's Common
Stock on the last day of the preceding month, equals 120 percent of the
outstanding principal amount of the Notes. The Pledge Agreement provides that,
in the event of a default by the Company in the payment of the Notes, shares of
the Company's Common Stock subject to the pledge will be sold and the proceeds
applied to payment of obligations. The Pledgors have executed the Pledge
Agreement, which, together with the Notes, provides that the failure of the
Pledgors to fulfill their obligations under the Pledge Agreement, including,
without limitation, the obligation to maintain the security, shall constitute an
event of default with respect to the Notes permitting a sale of the shares
subject to the pledge.
 
                                       55

<PAGE>
    There previously has been no public market for the Company's Common Stock
and there can be no assurance that an active public market for the Common Stock
will be developed or sustained after the Rescission Offer. In addition, even if
such a public market does develop, the obligations of the Pledgors to pledge
shares is limited to shares held of record by the Pledgors as of the date of
this Prospectus and there can be no assurance that the value of the Company's
Common Stock on such public market will be sustained at levels so that the
shares subject to the pledge will be sufficient to satisfy the obligations of
the Company in the event of a default by the Company in the payment of the
Notes.
 
REGISTRATION RIGHTS
 
    REPRESENTATIVE'S WARRANT.  The Representative's Warrant provides certain
rights with respect to the registration under the Securities Act of the 300,000
shares issuable upon exercise thereof (including the warrants included therein).
The Company has agreed that during the entire period between the first
anniversary and fifth anniversary after the date of the Unit Offering Prospectus
it will register the issuance of such shares upon the exercise of the
Representative's Warrant (and, if necessary, their resale) so as to permit their
public resale without restriction. These registration rights could result in
substantial future expense to the Company and could adversely affect the
Company's ability to complete future equity or debt financings. Furthermore, the
registration and sale of Common Stock of the Company held by or issuable to the
holders of registration rights, or even the potential of such sales, could have
an adverse effect on the market price of the securities offered hereby.
 
    OTHER REGISTRATION RIGHTS.  Holders of 834,568 shares of Common Stock, or
their transferees, are entitled to certain rights with respect to the
registration of such shares under the Securities Act. Under the terms of an
Agreement to Purchase Limited Partnership Interests dated as of August 4, 1992
among AGDG, the Company and ORTDF, if the Company purposes to register any of
its Common Stock for sale to the public, ORTDF may require the Company to
include in such registration any shares of Common Stock issued or issuable upon
the exercise of certain warrants to purchase Common Stock of the Company held by
ORTDF subject to certain conditions and limitations. As of the date of this
Prospectus, ORTDF held 957,452 shares of Common Stock and options to purchase
33,334 shares of Common Stock. ORTDF will not participate in this offering.
 
    Under the terms of a Registration Rights Agreement dated as of May 20, 1992
between the Company and Ice Bear, Inc., an Alaska corporation ("Ice Bear"), if
the Company proposed to register any of its stock or other securities under the
Act in connection with a public offering of those securities for cash, Ice Bear
may require the Company to include in such registration any shares of Common
Stock held or issued or issuable upon the exercise of certain warrants to
purchase Common Stock of the Company held by Ice Bear subject to certain
conditions and limitations. As of the date of this Prospectus, Ice Bear held
21,930 shares of Common Stock and warrants to purchase 219,334 shares of Common
Stock. Ice Bear will not participate in this offering.
 
                 SHARES OF THE COMPANY ELIGIBLE FOR FUTURE SALE
 
    There has been no public market for the Company's Common Stock or Warrants.
No prediction can be made of the effect, if any, that future market sales of
shares of Common Stock or the availability of such shares for sale will have on
the prevailing market price of the Common Stock following the proposed Unit
Offering. Nevertheless, sales of substantial amounts of such shares in the open
market following the Unit Offering could adversely affect the prevailing market
price of the Common Stock.
 
   
    Upon completion of the Unit Offering and assuming no exercise of outstanding
options and warrants to purchase Common Stock after December 31, 1996, the
Company will have 10,279,763 outstanding shares of Common Stock. See
"Description of Securities." The 1,500,000 shares of Common Stock which are
included in the Unit Offering (or 1,725,000 shares if the Overallotment Option
is exercised in full) by the Company and, subject to certain conditions, up to
1,725,000 shares of Common Stock issuable upon
    
 
                                       56

<PAGE>
   
exercise of the Warrants (including Warrants subject to the Overallotment
Option, and, commencing approximately 12 months after the date of the Unit
Offering Prospectus, up to 300,000 shares of Common Stock that are issuable upon
exercise of the Representatives' Warrants (including the Warrants included
therein), will, subject to any applicable state law restrictions on secondary
trading, be freely tradeable without restriction under the Securities Act,
except that any shares purchased by an "affiliate" of the Company (as that term
is defined in Rule 144 under the Securities Act) will be subject to the resale
limitations of Rule 144.
    
 
   
    The remaining 8,779,763 shares of Common Stock are "restricted" shares
within the meaning of Rule 144 under the Securities Act (the "Restricted
Shares"). Of this number, approximately 1,358,055 shares not subject to lock-up
agreements will be eligible for immediate resale without restriction under Rule
144(k) of the Securities Act. An additional 19,000 shares held for more than one
but less than two years by shareholders who are not affiliates of the Company
and who are not subject to lock-up agreements are eligible for sale under Rule
144 of the Securities Act, subject to the volume and other limitations
thereunder. Upon expiration of lock-up agreements with the underwriters of the
Unit Offering three months after the date of the Unit Offering Prospectus (or
earlier with the consent of the underwriter), approximately 56,000 shares will
be eligible for immediate resale subject to the limitations of Rule 144 and
approximately 1,492,035 shares will be eligible for resale immediately without
restriction pursuant to Rule 144(k). Upon expiration of lock-up agreements with
the underwriters six months after the date of the Unit Offering Prospectus (or
earlier with the consent of the underwriter), approximately 952,500 shares will
be eligible for immediate resale subject to the limitations of Rule 144 and
approximately 1,826,984 shares will be eligible for resale immediately without
restriction pursuant to Rule 144(k). Upon expiration of lock-up agreements with
the underwriters nine months after the date of the Unit Offering Prospectus (or
earlier with the consent of the underwriter), approximately 1,199,000 shares
will be eligible for immediate resale subject to the limitations of Rule 144 and
approximately 2,402,933 shares will be eligible for resale immediately without
restriction pursuant to Rule 144(k). Upon expiration of lock-up agreements with
the underwriters one year after the date of the Unit Offering Prospectus (or
earlier with the consent of the underwriter), approximately 5,943,911 shares
will be eligible for immediate resale subject to the limitations of Rule 144 and
approximately 2,835,352 shares will be eligible for resale immediately without
restriction pursuant to Rule 144(k). As of the date of this Prospectus, options
to purchase 1,126,886 shares of Common Stock have been granted under the Stock
Incentive Plan, which shares, if acquired pursuant to the exercise of options,
are subject to lock-up agreements which expire one year after the date of this
Prospectus (or earlier with the consent of the underwriter).
    
 
   
    In general, under Rule 144, as currently in effect, any person (or persons
whose shares are aggregated) who has beneficially owned Restricted Shares for at
least one year, is entitled to sell, within any three-month period, a number of
shares that does not exceed the greater of (i) 1% of the then outstanding shares
of the Company's Common Stock (approximately 102,798 shares immediately after
this offering) or (ii) the average weekly trading volume of the Company's Common
Stock in the Nasdaq National Market during the four calendar weeks immediately
preceding the date on which notice of the sale is filed with the Securities and
Exchange Commission. Sales pursuant to Rule 144 are also subject to certain
requirements relating to manner of sale, notice and availability of current
public information about the Company. A person who is not deemed to have been an
affiliate of the Company at any time during the 90 days immediately preceding
the sale and whose Restricted Shares have been fully-paid for two years since
the later of the date they were acquired from the Company or the date they were
acquired from an affiliate of the Company may sell such Restricted Shares under
Rule 144(k) without regard to the limitations and requirements described above.
Under Rule 701, shares privately issued under certain compensatory stock-based
plans, such as the Stock Incentive Plan, may be resold under Rule 144 by
non-affiliates, subject only to the manner of sale requirements, and by
affiliates without regard to the one-year holding period requirement, commencing
90 days after the Company becomes subject to certain periodic reporting
requirements.
    
 
                                       57

<PAGE>
    The remaining 3,569,030 shares have been registered in connection with the
Rescission Offer but are subject to the Pledge Agreement which secures the
payment of the Notes by the Company. These shares also are subject to a lock-up
agreement with the Representatives for one year after the effective date of the
Unit Offering.
 
    Shortly after the Unit Offering, the Company intends to file a registration
statement under the Securities Act covering shares of Common Stock reserved for
issuance under the Company's outstanding stock options and Stock Incentive Plan
(other than shares issued upon the exercise of options prior to the effective
date of such registration statement). Based on the number of options outstanding
and options and shares reserved for issuance, such registration statement would
cover approximately 1,333,333 shares. Such registration statement will
automatically become effective upon filing. All shares issuable under the
Company's Stock Incentive Plan are subject to a six-month lock-up period
following the date of the Unit Offering.
 
    There has been no established public market for the Common Stock. No
prediction can be made of the effect, if any, that sales of shares under Rule
144 or the availability of shares for sale will have on the market price of the
Common Stock prevailing from time to time after the offering. The Company is
unable to estimate the number of shares that may be sold in the public market
under Rule 144, because such amount will depend on the trading volume in, and
market price for, the Common Stock and other factors. Nevertheless, sales of
substantial amounts of shares in the public market, or the perception that such
sales could occur, could adversely affect the market price of the Common Stock
of the Company. See "Underwriting."
 
CERTAIN PROVISIONS OF THE COMPANY'S ARTICLES OF INCORPORATION AND BYLAWS
 
    Certain provisions of the Company's Articles of Incorporation and Bylaws
could make more difficult the acquisition of the Company by means of a tender
offer, a proxy contest or otherwise and the removal of incumbent officers and
directors. These provisions include authorization of the issuance of up to
2,000,000 shares of Preferred Stock, with such characteristics, and potential
effects on the acquisition of the Company, as are described in "Preferred Stock"
above. This provision is expected to discourage certain types of coercive
takeover practices and inadequate takeover bids and to encourage persons seeking
to acquire control of the Company to negotiate first with the Company. The
Company believes that the benefits of increased protection of the Company's
potential ability to negotiate with the proponent of an unfriendly or
unsolicited proposal to acquire or restructure the Company outweigh the
disadvantages of discouraging such proposals because, among other things,
negotiation of such proposals could result in an improvement of their terms. See
"Risk Factors--Anti-Takeover Effects of Certain Charter Provisions and Oregon
Law."
 
OREGON CONTROL SHARE AND BUSINESS COMBINATION STATUTES
 
    Upon completion of this offering, the Company will become subject to the
Oregon Control Share Act (the "Control Share Act"). The Control Share Act
generally provides that a person (the "Acquiring Person") who acquires voting
stock of an Oregon corporation in a transaction that results in the Acquiring
Person holding more than 20%, 33 1/3% or 50% of the total voting power of the
corporation (a "Control Share Acquisition") cannot vote the shares it acquires
in the Control Share Acquisition ("control shares") unless voting rights are
accorded to the control shares by (i) a majority of each voting group entitled
to vote and (ii) the holders of a majority of the outstanding voting shares,
excluding the control shares held by the Acquiring Person and shares held by the
Company's officers and inside directors. The term "Acquiring Person" is broadly
defined to include persons acting as a group.
 
    The Acquiring Person may, but is not required to, submit to the Company a
statement setting forth certain information about the Acquiring Person and its
plans with respect to the Company. The statement may also request that the
Company call a special meeting of shareholders to determine whether voting
 
                                       58

<PAGE>
rights will be accorded to the control shares. If the Acquiring Person does not
request a special meeting of shareholders, the issue of voting rights of control
shares will be considered at the next annual meeting or special meeting of
shareholders. If the Acquiring Person's control shares are accorded voting
rights and represent a majority or more of all voting power, shareholders who do
not vote in favor of voting rights for the control shares will have the right to
receive the appraised "fair value" of their shares which may not be less than
the highest price paid per share by the Acquiring Person for the control shares.
 
    Upon completion of this offering, the Company will become subject to certain
provision of the Oregon Business Corporation Act that govern business
combinations between corporations and interested shareholders (the "Business
Combination Act"). The Business Combination Act generally provides that if a
person or entity acquires 15% or more of the voting stock of an Oregon
corporation (an "Interested Shareholder"), the corporation and the Interested
Shareholder, or any affiliated entity of the Interested Shareholder, may not
engage in certain business combination transactions for three years following
the date the person became an Interested Shareholder. Business combination
transactions for this purpose include (a) a merger or plan of share exchange,
(b) any sales, lease, mortgage or other disposition of 10% or more of the assets
of the corporation and (c) certain transactions that result in the issuance of
capital stock of the corporation to the Interested Shareholder. These
restrictions do not apply if (i) the Interested Shareholder, as a result of the
transaction in which such person became an Interested Shareholder, owns at least
85% of the outstanding voting stock of the corporation (disregarding shares
owned by directors who are also officers and certain employee benefit plans),
(ii) the board of directors approves the share acquisition or business
combination before the Interested Shareholder acquires 15% or more of the
corporation's outstanding voting stock or (iii) the board of directors and the
holders of at least two-thirds of the outstanding voting stock of the
corporation (disregarding shares owned by the Interested Shareholder) approve
the transaction after the Interested Shareholder acquires 15% or more of the
corporation's voting stock. See "Risk Factors--Anti-Takeover Effects of Certain
Charter Provisions and Oregon Law."
 
TRANSFER AGENT AND REGISTRAR
 
    The Transfer Agent and Registrar for the Company's securities is ChaseMellon
Shareholder Services.
 
                        SELECTED FINANCIAL DATA OF AGDG
 

<TABLE>
<CAPTION>
                                                                        YEAR ENDED DECEMBER 31,
                                                                        -----------------------
                                                                          1995         1996
                                                                        ---------  ------------
<S>                                                                     <C>        <C>
Statement of Operations Data:
Interest revenue......................................................  $   9,593   $    7,343
Expenses..............................................................      4,104        3,115
                                                                        ---------  ------------
    Net income........................................................  $   5,489   $    4,228
                                                                        ---------  ------------
                                                                        ---------  ------------
</TABLE>

 

<TABLE>
<CAPTION>
                                                                                  DECEMBER 31,
                                                                                      1996
                                                                                  ------------
<S>                                                                               <C>
Balance Sheet Data:
Working capital.................................................................   $  188,784
Total assets....................................................................      189,139
Partners' capital...............................................................      189,139
</TABLE>

 
                                       59

<PAGE>
                    MANAGEMENT'S DISCUSSION AND ANALYSIS OF
             FINANCIAL CONDITION AND RESULTS OF OPERATIONS OF AGDG
 
OVERVIEW
 
    From inception in 1981, the partnership has devoted its resources primarily
to contract for its research and development efforts in the field of antisense.
The Partnership has had limited interest revenue and has had no revenues to date
from the sale of products or other sources, and does not expect revenues from
such sources for at least the next 12 months. The partnership expects to
continue to earn small amounts of interest revenue for the foreseeable future.
 
RESULTS OF OPERATIONS
 
    YEAR ENDED DECEMBER 31, 1995 COMPARED TO YEAR ENDED DECEMBER 31, 1996.  The
partnership had interest revenues of $9,593 and $7,343 for the years ended
December 31, 1995 and December 31, 1996 respectively. Revenues for both time
periods were derived from interest on certificates of deposit and short-term
investments. The decrease between the prior and current year periods was due
primarily to fluctuations in the market interest rates paid on such investments.
Operating expenses were $4,104 and $3,115 for the years ended December 31, 1995
and 1996 respectively. The decrease in expenses was due to savings on
professional services and a decrease in miscellaneous expenses.
 
LIQUIDITY AND CAPITAL RESOURCES
 
    The Company has financed its operations since inception primarily through
private equity sales. Since 1992, the partnership has not actively engaged in
fundraising, and currently exists primarily for the purpose of collecting
revenues, if any, which arise under the terms of a Technology Transfer Agreement
between AGDG and the Company.
 
    If additional partnership units are issued in connection with this offering,
the rights and returns of existing partners are not expected to be significantly
impacted as payments from the Company connected with sales of therapeutic
products will increase on a pro rata basis for each additional partnership
interest issued, such that if all unit holders accept the rescission offer, the
fees for the sales of therapeutic products will increase to approximately 5.23%.
Fees related to diagnostic products under the Technology Transfer Agreement
would remain at 2%.
 
                                BUSINESS OF AGDG
 
    The Anti-Gene Development Group was formed in 1981 under the Oregon Uniform
Limited Partnership Act for the purpose of funding the development of and
obtaining the proprietary rights to Anti-Genes. Prior to 1993, AGDG periodically
contracted with the Company to develop the technologies while retaining the
rights to the resultant technologies. Substantially all of the proceeds from
sales of interests in AGDG and interest income were paid to the Company under
the terms of these research and development contracts.
 
    Sole management of AGDG is vested in the general partner. The general
partner of AGDG is Dr. James Summerton, founder and Chairman and Chief Executive
Officer of the Company, until January 1996. Dr. Summerton presently serves as
President and Chief Scientific Officer of the Company. Dr. Summerton receives no
fees or other remuneration for his management of AGDG.
 
    In February, 1993, to facilitate additional capital raising activities
associated with the development of the technologies, AGDG and the Company
entered into a Technology Transfer Agreement whereby effective May 19, 1993,
AGDG conveyed all intellectual property in its control to the Company. In
consideration of this transfer, the Company is obligated to pay to AGDG certain
technology transfer fees arising from the sale of products incorporating the
technologies.
 
                                       60

<PAGE>
    During March, 1993, the Company offered all holders of interests in AGDG the
opportunity to exchange their units of limited partnership interest for shares
of the Common Stock of the Company at a ratio of 1,100 shares of Common Stock
for each unit exchanged. The exchange ratio was determined based on historical
perceptions by the partners of AGDG and shareholders of the Company as to the
relative values of AGDG, but was not confirmed by financial analysis of any
kind. The exchange offer was the subject of a fairness hearing conducted by the
Oregon Department of Insurance and Finance on April 19, 1993, and after such
hearing the Oregon Department of Insurance and Finance issued an order
permitting the exchange offering to proceed.
 
    Upon completion of the exchange offer and the technology transfer agreement,
the partnership ceased active sales of partnership interests and no longer
enters into research and development contracts with the Company. The partnership
currently exists primarily for the purpose of collecting revenues, if any, which
may arise under the term of a Technology Transfer Agreement between AGDG and the
Company. There can be no assurance that the Company will successfully develop or
commercialize the technologies which are the subject of the Technology Transfer
Agreement. For a detailed statement of the risks associated with the Company,
see "Risk Factors."
 
                               MANAGEMENT OF AGDG
 
    The General Partner of AGDG and his age are as follows:
 

<TABLE>
<CAPTION>
NAME                                                                      AGE           POSITION
- --------------------------------------------------------------------      ---      ------------------
<S>                                                                   <C>          <C>
James E. Summerton, Ph.D............................................          52      General Partner
</TABLE>

 
    JAMES E. SUMMERTON, PH.D.  founded AGDG in 1981 and has served as its
General Partner since that time. He has been President and Chief Scientific
Officer of ANTIVIRALS Inc. since January 1996. He founded ANTIVIRALS in 1980 and
was its Chairman and Chief Executive Officer until January 1996. He held the
position of assistant professor of Biochemistry-Biophysics at Oregon State
University from 1978 to 1980. He is the inventor or co-inventor on all of the
Company's patents and pending applications. Dr. Summerton received a B.S. in
Chemistry from Northern Arizona University and a Ph.D. from the University of
Arizona. Dr. Summerton first conceived of the concept of sequence-specific
gene-inactivation in 1969.
 
                             EXECUTIVE COMPENSATION
 
    The General Partner receives no remuneration.
 
                       PRINCIPAL INTEREST HOLDERS OF AGDG
 
    The following table sets forth certain information with respect to the
beneficial ownership of the partnership's units of limited partnership interest,
and as adjusted to give effect to the Rescission Offer. The information as to
each person or entity has been furnished by such person or entity, and unless
 
                                       61

<PAGE>
otherwise indicated, the persons named in the table have sole voting and sole
investment power with respect to all shares beneficially owned, subject to
community property laws where applicable.
 

<TABLE>
<CAPTION>
                                                                                                   PERCENT OF UNITS
                                                                                                     OUTSTANDING
                                                                                    UNITS      ------------------------
                                                                                BENEFICIALLY     BEFORE        AFTER
NAME AND ADDRESS OF BENEFICIAL OWNER                                              OWNED(1)      OFFERING    OFFERING(3)
- ------------------------------------------------------------------------------  -------------  -----------  -----------
<S>                                                                             <C>            <C>          <C>
James E. Summerton, Ph.D.(2)..................................................        1,476         79.5%        60.9%
  Anti-gene Development Group
  3107 NW Norwood Place
  Corvallis, OR 97330
</TABLE>

 
- ------------------------
 
(1) Beneficial ownership is determined in accordance with the rules of the
    Securities and Exchange Commission and generally includes voting or
    investment power with respect to securities. Limited partnership units
    subject to options and warrants currently exercisable or convertible, or
    exercisable or convertible within 60 days of February 28, 1997 are deemed
    beneficially owned and outstanding for computing the percentage of the
    person holding such securities, but are not considered outstanding for
    computing the percentage of any other person.
 
(2) Includes 52 units held by others over which Dr. Summerton exercises voting
    and investment power.
 
(3) Assumes issuance of 568.67 units upon acceptance of the rescission offer by
    all eligible former exchange offer participants.
 
                       DESCRIPTION OF SECURITIES OF AGDG
 
    As of the date of this Prospectus, 1,856 units of limited partnership
interest in AGDG were outstanding. If all Eligible Offerees who participated in
the exchange offer tender their 625,537 shares and 568.67 units of limited
partnership interest are issued therefor, 2,424.67 units of limited partnership
interest will be outstanding.
 
    The units represent limited partnership interests in the AGDG limited
partnership. The liability of each limited partner of AGDG is limited to the
amount of that partner's investment in the partnership, together with their
interest in undistributed income, if any. Partnership units are nonassessable,
and no additional contributions to the Partnership's capital may be required of
the limited partners at any time by way of assessment.
 
    The share of the profits and losses to which each partner is entitled is
established by the Anti-Gene Development Group Certificate of Limited
Partnership. Losses, up to the amount invested, are allocated yearly in direct
proportion to the amount of capital each Partner has invested during that year,
or during that phase if the phase is less than one year. Losses are calculated
on a first-in first-out basis. Any additional losses are allocated pro rata to
all partnership interests. Profits, if any, are distributed pro rata to all
partnership interests.
 
    There currently is no public trading market for units of interest in AGDG
and AGDG does not anticipate that such a market will develop.
 
                                 LEGAL MATTERS
 
    The validity of the Notes offered hereby will be passed upon for the Company
by Ater Wynne Hewitt Dodson & Skerritt, LLP, Portland, Oregon.
 
                                       62

<PAGE>
                                    EXPERTS
 
    The financial statements of the Company as of December 31, 1995 and for each
of the two years in the period ended December 31, 1995 appearing in this
Prospectus have been audited by Arthur Andersen LLP, independent auditors, as
set forth in their report thereon appearing elsewhere herein, and are included
in reliance upon such report given upon the authority of such firm as experts in
accounting and auditing.
 
   
    The information contained in "Risk Factors--Patents and Proprietary Rights"
and in "Business-- Patents and Proprietary Rights" has been reviewed and
approved by Peter Dehlinger & Associates, Palo Alto, California, patent counsel
to the Company, as experts in such matters, and is included in reliance upon
their review and approval.
    
 
                             ADDITIONAL INFORMATION
 
    The Company has filed with the Securities and Exchange Commission (the
"Commission") a Registration Statement on Form SB-2 under the Securities Act
with respect to the Rescission Offer, of which this Prospectus forms a part.
This Prospectus does not contain all of the information set forth in the
Registration Statement and the exhibits and schedules thereto. For further
information with respect to the Company and its Common Stock, reference is made
to the Registration Statement and such exhibits and schedules. Statements
contained in this Prospectus as to the contents of any contract or other
documents referred to are not necessarily complete and, in each instance, if
such contract or document is filed as an exhibit to the Registration Statement,
reference is made to the copy of such contract or document filed as an exhibit,
each such statement being qualified in all respects by such reference to such
exhibit. The Registration Statement and the exhibits and schedules thereto may
be inspected without charge at the Commission's principal office in Washington,
D.C., and copies of all or any part thereof may be obtained from the Public
Reference Section of the Commission, 450 Fifth Street, N.W., Washington, D.C.
20549, upon payment of certain fees prescribed by the Commission. The Commission
also maintains a site on the World Wide Web that contains reports, proxy and
information statements and other information regarding registrants that file
electronically with the Commission. The address of such site is
http://www.sec.gov.
 
                                       63

<PAGE>
                                ANTIVIRALS INC.
                         INDEX TO FINANCIAL STATEMENTS
 

<TABLE>
<S>                                                                                     <C>
Report of Independent Public Accountants..............................................        F-2
 
Balance Sheets as of December 31, 1995 and 1996.......................................        F-3
 
Statements of Operations for the two years ended December 31, 1996....................        F-4
 
Statements of Shareholders' Equity for the seventeen years ended December 31, 1996....        F-5
 
Statements of Cash Flows for the two years ended December 31, 1996....................        F-8
 
Notes to Financial Statements.........................................................        F-9

</TABLE>

 
                                      F-1

<PAGE>

                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
To the Board of Directors and Shareholders of
 
ANTIVIRALS INC.
 
    We have audited the accompanying balance sheets of ANTIVIRALS INC. (an
Oregon corporation in the development stage) as of December 31, 1995 and 1996,
and the related statements of operations, shareholders' equity and cash flows
for the years ended December 31, 1995 and 1996 and for the period from inception
(July 22, 1980) to December 31, 1996. These financial statements are the
responsibility of the Company's management. Our responsibility is to express an
opinion on these financial statements based on our audits.
 
    We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
    In our opinion, the financial statements referred to above present fairly,
in all material respects, the financial position of ANTIVIRALS INC. as of
December 31, 1995 and 1996, and the results of its operations and its cash flows
for the years ended December 31, 1995 and 1996 and for the period from inception
(July 22, 1980) to December 31, 1996, in conformity with generally accepted
accounting principles.
 
    The accompanying financial statements have been prepared assuming that the
Company will continue as a going concern. As discussed in Note 1 to the
financial statements, the Company has suffered recurring losses from operations
and, at December 31, 1996, has a deficit accumulated during the development
stage of $12,425,483. In addition, as more fully discussed in Note 7 to the
financial statements, the Company has filed with certain securities regulators a
registration statement pertaining to a planned rescission offering for certain
purchasers' equity securities because Company management cannot draw a
conclusion with certainty that all applicable state and federal securities laws
were complied with in all material respects in connection with the issuance of
such securities. Such factors raise substantial doubt about the Company's
ability to continue as a going concern. Management's plan in regard to these
matters is also described in Note 1. The financial statements do not include any
adjustments that might result from the outcome of these uncertainties.
 
ARTHUR ANDERSEN LLP
 
Portland, Oregon,
March 10, 1997

 
                                      F-2

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                                 BALANCE SHEETS
 
                                     ASSETS
 

<TABLE>
<CAPTION>
                                                                                             DECEMBER 31,
                                                                                    ------------------------------
                                                                                         1995            1996
                                                                                    --------------  --------------
<S>                                                                                 <C>             <C>
CURRENT ASSETS:
  Cash and cash equivalents.......................................................  $      680,892  $    3,011,229
  Short-term securities--available-for-sale.......................................         212,750          30,000
  Other current assets............................................................           7,236          28,255
                                                                                    --------------  --------------
      Total current assets........................................................         900,878       3,069,484
                                                                                    --------------  --------------
PROPERTY AND EQUIPMENT, at cost:
  Laboratory equipment............................................................         677,728         738,160
  Office equipment................................................................         181,803         187,248
  Leasehold improvements..........................................................       1,464,603       1,464,603
                                                                                    --------------  --------------
                                                                                         2,324,134       2,390,011
  Less--Accumulated depreciation and amortization.................................      (1,379,377)     (1,858,359)
                                                                                    --------------  --------------
                                                                                           944,757         531,652
                                                                                    --------------  --------------
PATENT COSTS, net.................................................................         449,254         474,806
DEFERRED OFFERING COSTS...........................................................        --               143,110
OTHER ASSETS......................................................................          29,847          29,847
                                                                                    --------------  --------------
                                                                                    $    2,324,736  $    4,248,899
                                                                                    --------------  --------------
                                                                                    --------------  --------------
 
                                       LIABILITIES AND SHAREHOLDERS' EQUITY
 
CURRENT LIABILITIES:
  Accounts payable................................................................  $       85,298  $      153,202
  Accrued payroll.................................................................         149,715         169,609
  Deferred payments...............................................................          19,051           7,996
                                                                                    --------------  --------------
      Total current liabilities...................................................         254,064         330,807
                                                                                    --------------  --------------
COMMON STOCK SUBJECT TO RESCISSION, $.0001 par value, 1,292,973 issued and
  outstanding.....................................................................       3,121,965       3,121,965
                                                                                    --------------  --------------
SHAREHOLDERS' EQUITY:
  Preferred stock, $.0001 par value, 2,000,000 shares authorized; none issued and
    outstanding...................................................................        --              --
  Common stock, $.0001 par value, 50,000,000 shares authorized; 5,816,838 and
    7,486,790 shares issued and outstanding in 1995 and 1996, respectively........             582             749
  Additional paid-in capital......................................................       9,189,496      13,220,861
  Unrealized gain on available-for-sale securities................................          96,750        --
  Deficit accumulated during the development stage................................     (10,338,121)    (12,425,483)
                                                                                    --------------  --------------
      Total shareholders' (deficit) equity........................................      (1,051,293)        796,127
                                                                                    --------------  --------------
                                                                                    $    2,324,736  $    4,248,899
                                                                                    --------------  --------------
                                                                                    --------------  --------------
</TABLE>

 
                            See accompanying notes.
 
                                      F-3

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                            STATEMENTS OF OPERATIONS
 

<TABLE>
<CAPTION>
                                                                                                    JULY 22, 1980
                                                                        YEAR ENDED DECEMBER 31,     (INCEPTION) TO
                                                                      ----------------------------   DECEMBER 31,
                                                                          1995           1996            1996
                                                                      -------------  -------------  --------------
<S>                                                                   <C>            <C>            <C>
REVENUES, from grants and research contracts........................  $      82,500  $      27,227  $      689,497
                                                                      -------------  -------------  --------------
 
OPERATING EXPENSES:
  Research and development..........................................      2,097,796      1,729,554       9,011,574
  General and administrative........................................        609,723        613,811       4,549,582
                                                                      -------------  -------------  --------------
      Total operating expenses......................................      2,707,519      2,343,365      13,561,156
                                                                      -------------  -------------  --------------
 
OTHER INCOME........................................................         68,133        228,776         446,176
                                                                      -------------  -------------  --------------
NET LOSS............................................................  $  (2,556,886) $  (2,087,362) $  (12,425,483)
                                                                      -------------  -------------  --------------
                                                                      -------------  -------------  --------------
 
NET LOSS PER SHARE..................................................  $       (0.37) $       (0.25)
                                                                      -------------  -------------
                                                                      -------------  -------------
SHARES USED IN PER SHARE CALCULATION................................      6,982,459      8,233,548
                                                                      -------------  -------------
                                                                      -------------  -------------
</TABLE>

 
                            See accompanying notes.
 
                                      F-4

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                       STATEMENTS OF SHAREHOLDERS' EQUITY

<TABLE>
<CAPTION>
                                                                                                   UNREALIZED     DEFICIT
                                                                                                     GAIN ON    ACCUMULATED
                                                                   COMMON STOCK        ADDITIONAL  AVAILABLE-    DURING THE
                                                 PARTNERSHIP  -----------------------   PAID-IN     FOR-SALE    DEVELOPMENT
                                                    UNITS       SHARES      AMOUNT      CAPITAL    SECURITIES      STAGE
                                                 -----------  ----------  -----------  ----------  -----------  ------------
<S>                                              <C>          <C>         <C>          <C>         <C>          <C>
BALANCE AT JULY 22, 1980 (inception)...........      --           --       $  --       $   --       $  --        $   --
  No activity
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1980....................      --           --          --           --          --            --
  Issuance of partnership units and common
    stock in October 1981 for equipment and
    supplies valued at $3,500 and technology...     1,000      1,666,667         167        3,333      --            --
  Issuance of partnership units and common
    stock for cash, $500 per unit..............       150        250,000          25       75,055      --            --
  Issuance of partnership units for consulting
    services, $500 per unit....................        10         --          --            5,000      --            --
  Issuance of common stock in connection with
    financing agreement........................      --           33,333           3            7      --            --
  Net loss.....................................      --           --          --           --          --            (9,224)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1981....................     1,160      1,950,000         195       83,395      --            (9,224)
  Issuance of common stock for consulting
    services...................................      --           54,600           5           11      --            --
  Net loss.....................................      --           --          --           --          --           (57,962)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1982....................     1,160      2,004,600         200       83,406      --           (67,186)
  Issuance of partnership units and common
    stock for cash, $550 per unit..............        60        100,000          10       33,020      --            --
  Issuance of common stock for consulting
    services...................................      --           21,733           2            5      --            --
  Net loss.....................................      --           --          --           --          --           (27,475)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1983....................     1,220      2,126,333         212      116,431      --           (94,661)
  Issuance of partnership units and common
    stock for cash, $600 per unit..............        10         16,667           2        6,003      --            --
  Issuance of partnership units and common
    stock for consulting services and $1,000
    cash, $550 to $600 per unit................        20         16,667           2       11,503      --            --
  Issuance of common stock for consulting
    services...................................      --            2,533      --                1      --            --
  Issuance of common stock for donation to
    charitable organizations...................      --          100,000          10           20      --            --
  Net loss.....................................      --           --          --           --          --           (21,463)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1984....................     1,250      2,262,200         226      133,958      --          (116,124)
  Issuance of partnership units and common
    stock in December 1984 for technology......     1,000        166,667          16          (16)     --            --
  Issuance of partnership units and common
    stock for cash, $50 to $100 per unit.......       460         78,333           8       23,515      --            --
  Issuance of partnership units for cash, $50
    to $550 per unit...........................       140         --          --           17,000      --            --
  Issuance of common stock for consulting
    services...................................      --            6,733           1            1      --            --
  Net loss.....................................      --           --          --           --          --            (8,469)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1985....................     2,850      2,513,933         251      174,458      --          (124,593)
  Issuance of partnership units and common
    stock for cash, $50 to $500 per unit.......        90        105,000          11       31,521      --            --
  Issuance of common stock for consulting
    services...................................      --            8,500           1            1      --            --
  Net loss.....................................      --           --          --           --          --           (32,353)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1986....................     2,940      2,627,433         263      205,980      --          (156,946)
  Issuance of partnership units and common
    stock for cash, $500 per unit..............        20         33,333           3       10,007      --            --
  Issuance of partnership units and warrants to
    purchase 400,000 shares of common stock for
    cash, $500 to $2,500 per unit..............        80         --          --          100,000      --            --
  Issuance of common stock for consulting
    services...................................      --           28,533           3            6      --            --
  Net loss.....................................      --           --          --           --          --           (71,616)
                                                 -----------  ----------       -----   ----------  -----------  ------------
BALANCE AT OCTOBER 31, 1987....................     3,040      2,689,299         269      315,993      --          (228,562)
 
<CAPTION>
 
                                                     TOTAL
                                                 SHAREHOLDERS'
                                                    EQUITY
                                                 -------------
<S>                                              <C>
BALANCE AT JULY 22, 1980 (inception)...........   $   --
  No activity
                                                 -------------
BALANCE AT OCTOBER 31, 1980....................       --
  Issuance of partnership units and common
    stock in October 1981 for equipment and
    supplies valued at $3,500 and technology...         3,500
  Issuance of partnership units and common
    stock for cash, $500 per unit..............        75,080
  Issuance of partnership units for consulting
    services, $500 per unit....................         5,000
  Issuance of common stock in connection with
    financing agreement........................            10
  Net loss.....................................        (9,224)
                                                 -------------
BALANCE AT OCTOBER 31, 1981....................        74,366
  Issuance of common stock for consulting
    services...................................            16
  Net loss.....................................       (57,962)
                                                 -------------
BALANCE AT OCTOBER 31, 1982....................        16,420
  Issuance of partnership units and common
    stock for cash, $550 per unit..............        33,030
  Issuance of common stock for consulting
    services...................................             7
  Net loss.....................................       (27,475)
                                                 -------------
BALANCE AT OCTOBER 31, 1983....................        21,982
  Issuance of partnership units and common
    stock for cash, $600 per unit..............         6,005
  Issuance of partnership units and common
    stock for consulting services and $1,000
    cash, $550 to $600 per unit................        11,505
  Issuance of common stock for consulting
    services...................................             1
  Issuance of common stock for donation to
    charitable organizations...................            30
  Net loss.....................................       (21,463)
                                                 -------------
BALANCE AT OCTOBER 31, 1984....................        18,060
  Issuance of partnership units and common
    stock in December 1984 for technology......       --
  Issuance of partnership units and common
    stock for cash, $50 to $100 per unit.......        23,523
  Issuance of partnership units for cash, $50
    to $550 per unit...........................        17,000
  Issuance of common stock for consulting
    services...................................             2
  Net loss.....................................        (8,469)
                                                 -------------
BALANCE AT OCTOBER 31, 1985....................        50,116
  Issuance of partnership units and common
    stock for cash, $50 to $500 per unit.......        31,532
  Issuance of common stock for consulting
    services...................................             2
  Net loss.....................................       (32,353)
                                                 -------------
BALANCE AT OCTOBER 31, 1986....................        49,297
  Issuance of partnership units and common
    stock for cash, $500 per unit..............        10,010
  Issuance of partnership units and warrants to
    purchase 400,000 shares of common stock for
    cash, $500 to $2,500 per unit..............       100,000
  Issuance of common stock for consulting
    services...................................             9
  Net loss.....................................       (71,616)
                                                 -------------
BALANCE AT OCTOBER 31, 1987....................        87,700
</TABLE>

 
                            See accompanying notes.
 
                                      F-5

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                       STATEMENTS OF SHAREHOLDERS' EQUITY

<TABLE>
<CAPTION>
                                                                                                                         DEFICIT
                                                                                                                       ACCUMULATED
                                                                   COMMON STOCK        ADDITIONAL    UNREALIZED GAIN    DURING THE
                                                PARTNERSHIP  ------------------------    PAID-IN    ON AVAILABLE-FOR-  DEVELOPMENT
                                                   UNITS       SHARES       AMOUNT       CAPITAL     SALE SECURITIES      STAGE
                                                -----------  -----------  -----------  -----------  -----------------  ------------
<S>                                             <C>          <C>          <C>          <C>          <C>                <C>
BALANCE AT OCTOBER 31, 1987...................     3,040       2,689,299   $     269   $   315,993         --          $   (228,562)
  Issuance of partnership units and common
    stock for cash, $500 per unit.............       100         166,667          17        50,033         --               --
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........        20          33,333           3        25,007         --               --
  Issuance of partnership units for cash, $50
    per unit..................................        20         --           --             1,000         --               --
  Issuance of partnership units and warrants
    to purchase 400,000 shares of common for
    cash, $1,250 per unit.....................        80         --           --           100,000         --               --
  Compensation expense related to issuance of
    warrants for partnership units............      --           --           --            10,000         --               --
  Issuance of common stock for consulting
    services and employee compensation........      --            47,014           5             9         --               --
  Net loss....................................      --           --           --           --              --              (266,194)
                                                -----------  -----------       -----   -----------        -------      ------------
BALANCE AT OCTOBER 31, 1988...................     3,260       2,936,313         294       502,042         --              (494,756)
  Exercise of warrants for common stock.......      --           141,667          14            28         --               --
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........        10          16,667           1        12,504         --               --
  Issuance of partnership units and warrants
    to purchase 800,000 shares of common stock
    for cash, $1,250 per unit.................       160         --           --           200,000         --               --
  Issuance of common stock for consulting
    services and employee compensation........      --            17,733           2             4         --               --
  Compensation expense related to issuance of
    warrants for partnership units............      --           --           --             2,500         --               --
  Net loss....................................      --           --           --           --              --              (243,926)
                                                -----------  -----------       -----   -----------        -------      ------------
BALANCE AT OCTOBER 31, 1989...................     3,430       3,112,380         311       717,078         --              (738,682)
  Exercise of warrants for common stock.......      --            33,333           3             7         --               --
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........        74         123,334          12        92,525         --               --
  Issuance of partnership unit for cash,
    $5,000 per unit...........................         1         --           --             5,000         --               --
  Issuance of common stock for cash, $4.56 per
    share.....................................      --             1,100      --             5,000         --               --
  Issuance of partnership units and warrants
    to purchase 200,000 shares of common stock
    for cash, $1,250 per unit.................        40         --           --            50,000         --               --
  Issuance of common stock for consulting
    services and employee compensation........      --            11,400           2        51,678         --               --
  Compensation expense related to issuance of
    warrants for partnership units............      --           --           --            40,000         --               --
  Exercise of warrant for partnership units...        10         --           --            12,500         --               --
  Net loss....................................      --           --           --           --              --              (351,772)
                                                -----------  -----------       -----   -----------        -------      ------------
BALANCE AT OCTOBER 31, 1990...................     3,555       3,281,547         328       973,788         --            (1,090,454)
  Issuance of partnership units for cash,
    $5,000 per unit...........................        23.5       --           --           117,500         --               --
  Exercise of warrants for partnership unit
    and common stock..........................         1           1,100      --             1,250         --               --
  Issuance of common stock for cash, $4.56 per
    share.....................................      --            24,750           3       112,505         --               --
  Compensation expense related to issuance of
    warrants for common stock.................      --           --           --             1,520         --               --
  Issuance of common stock for consulting
    services, $4.56 per share.................      --             1,657      --             7,547         --               --
  Common stock subject to rescission..........      --            (7,127)         (1)      (32,499)        --               --
  Net loss....................................      --           --           --           --              --              (274,844)
                                                -----------  -----------       -----   -----------        -------      ------------
BALANCE AT OCTOBER 31, 1991...................     3,579.5     3,301,927         330     1,181,611         --            (1,365,298)
 
<CAPTION>
 
                                                      TOTAL
                                                  SHAREHOLDERS'
                                                      EQUITY
                                                ------------------
<S>                                             <C>
BALANCE AT OCTOBER 31, 1987...................     $     87,700
  Issuance of partnership units and common
    stock for cash, $500 per unit.............           50,050
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........           25,010
  Issuance of partnership units for cash, $50
    per unit..................................            1,000
  Issuance of partnership units and warrants
    to purchase 400,000 shares of common for
    cash, $1,250 per unit.....................          100,000
  Compensation expense related to issuance of
    warrants for partnership units............           10,000
  Issuance of common stock for consulting
    services and employee compensation........               14
  Net loss....................................         (266,194)
                                                ------------------
BALANCE AT OCTOBER 31, 1988...................            7,580
  Exercise of warrants for common stock.......               42
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........           12,505
  Issuance of partnership units and warrants
    to purchase 800,000 shares of common stock
    for cash, $1,250 per unit.................          200,000
  Issuance of common stock for consulting
    services and employee compensation........                6
  Compensation expense related to issuance of
    warrants for partnership units............            2,500
  Net loss....................................         (243,926)
                                                ------------------
BALANCE AT OCTOBER 31, 1989...................          (21,293)
  Exercise of warrants for common stock.......               10
  Issuance of partnership units and common
    stock for cash, $1,250 per unit...........           92,537
  Issuance of partnership unit for cash,
    $5,000 per unit...........................            5,000
  Issuance of common stock for cash, $4.56 per
    share.....................................            5,000
  Issuance of partnership units and warrants
    to purchase 200,000 shares of common stock
    for cash, $1,250 per unit.................           50,000
  Issuance of common stock for consulting
    services and employee compensation........           51,680
  Compensation expense related to issuance of
    warrants for partnership units............           40,000
  Exercise of warrant for partnership units...           12,500
  Net loss....................................         (351,772)
                                                ------------------
BALANCE AT OCTOBER 31, 1990...................         (116,338)
  Issuance of partnership units for cash,
    $5,000 per unit...........................          117,500
  Exercise of warrants for partnership unit
    and common stock..........................            1,250
  Issuance of common stock for cash, $4.56 per
    share.....................................          112,508
  Compensation expense related to issuance of
    warrants for common stock.................            1,520
  Issuance of common stock for consulting
    services, $4.56 per share.................            7,547
  Common stock subject to rescission..........          (32,500)
  Net loss....................................         (274,844)
                                                ------------------
BALANCE AT OCTOBER 31, 1991...................         (183,357)
</TABLE>

 
                            See accompanying notes.
 
                                      F-6

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                 STATEMENTS OF SHAREHOLDERS' EQUITY (CONTINUED)

<TABLE>
<CAPTION>
                                                                                                                UNREALIZED
                                                                                                                  GAIN ON
                                                                               COMMON STOCK        ADDITIONAL   AVAILABLE-
                                                            PARTNERSHIP  ------------------------    PAID-IN     FOR-SALE
                                                               UNITS       SHARES       AMOUNT       CAPITAL    SECURITIES
                                                            -----------  -----------  -----------  -----------  -----------
<S>                                                         <C>          <C>          <C>          <C>          <C>
BALANCE AT OCTOBER 31, 1991...............................      3,579.5    3,301,927   $     330   $ 1,181,611      --
  Issuance of partnership units for cash, $5,000 per
    unit..................................................         15.5      --           --            77,500      --
  Issuance of common stock for cash, $4.56 per share......      --            17,050           2        77,498      --
  Compensation expense related to issuance of warrants for
    common stock..........................................      --           --           --             7,500      --
  Common stock subject to rescission......................      --           (32,486)         (3)     (148,135)     --
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1991..............................      3,595      3,286,491         329     1,195,974      --
  Issuance of partnership units for cash, $5,000 per
    unit..................................................         30.5      --           --           152,500      --
  Exercise of warrants for partnership units and common
    stock.................................................         22          2,200      --            28,750      --
  Conversion of debt into common stock and partnership
    units.................................................          9          9,634           1        87,859      --
  Issuance of common stock for cash, $4.56 per share......      --           868,906          87     3,954,625      --
  Issuance of common stock for consulting services, $4.56
    per share.............................................      --            22,872           2       104,167      --
  Compensation expense related to issuance of warrants for
    common stock and partnership units....................      --           --           --           262,833      --
  Common stock subject to rescission......................      --          (410,099)        (41)   (1,870,008)     --
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1992..............................      3,656.5    3,780,004         378     3,916,700      --
  Exercise of warrants for partnership units..............          9        --           --             4,500      --
  Issuance of common stock in exchange for partnership
    units.................................................     (1,809.5)   1,632,950         163          (163)     --
  Withdrawal of partnership net assets upon conveyance of
    technology............................................    (1,856)        --           --          (176,642)     --
  Issuance of common stock for cash and short-term
    investments, $4.95 per share..........................      --           507,084          50     2,510,014      --
  Exercise of warrants for common stock...................      --             3,844           1         9,999      --
  Common stock subject to rescission......................      --          (808,902)        (81)     (901,119)     --
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1993..............................      --         5,114,980         511     5,363,289      --
  Issuance of common stock for cash, $4.95 per share......      --           565,216          57     2,797,761      --
  Exercise of warrants for common stock...................      --            24,667           2       122,098      --
  Issuance of common stock for consulting services, $4.95
    per share.............................................      --               151      --               749      --
  Unrealized gain on available-for-sale securities........      --           --           --           --           61,000
  Common stock subject to rescission......................      --           (34,359)         (3)     (170,075)     --
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1994..............................      --         5,670,655         567     8,113,822      61,000
  Issuance of common stock for cash, $6.00 per share......      --           146,183          15       862,674      --
  Compensation expense related to issuance of warrants for
    common stock..........................................      --           --           --           213,000      --
  Unrealized gain on available-for-sale securities........      --           --           --           --           35,750
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1995..............................      --         5,816,838         582     9,189,496      96,750
  Exercise of warrants for common stock...................      --           957,452          96           (96)     --
  Issuance of common stock for cash, $6.00 per share......      --           712,500          71     4,031,461      --
  Liquidation of available-for-sale securities............      --           --           --           --          (96,750)
  Net loss................................................      --           --           --           --           --
                                                            -----------  -----------       -----   -----------  -----------
BALANCE AT DECEMBER 31, 1996..............................      --         7,486,790   $     749   $13,220,861      --
                                                            -----------  -----------       -----   -----------  -----------
                                                            -----------  -----------       -----   -----------  -----------
 
<CAPTION>
                                                              DEFICIT
                                                            ACCUMULATED
                                                             DURING THE       TOTAL
                                                            DEVELOPMENT   SHAREHOLDERS'
                                                               STAGE         EQUITY
                                                            ------------  -------------
<S>                                                         <C>           <C>
BALANCE AT OCTOBER 31, 1991...............................  $ (1,365,298)  $  (183,357)
  Issuance of partnership units for cash, $5,000 per
    unit..................................................       --             77,500
  Issuance of common stock for cash, $4.56 per share......       --             77,500
  Compensation expense related to issuance of warrants for
    common stock..........................................       --              7,500
  Common stock subject to rescission......................       --           (148,138)
  Net loss................................................       (91,588)      (91,588)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1991..............................    (1,456,886)     (260,583)
  Issuance of partnership units for cash, $5,000 per
    unit..................................................       --            152,500
  Exercise of warrants for partnership units and common
    stock.................................................       --             28,750
  Conversion of debt into common stock and partnership
    units.................................................       --             87,860
  Issuance of common stock for cash, $4.56 per share......       --          3,954,712
  Issuance of common stock for consulting services, $4.56
    per share.............................................       --            104,169
  Compensation expense related to issuance of warrants for
    common stock and partnership units....................       --            262,833
  Common stock subject to rescission......................       --         (1,870,049)
  Net loss................................................    (1,731,138)   (1,731,138)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1992..............................    (3,188,024)      729,054
  Exercise of warrants for partnership units..............       --              4,500
  Issuance of common stock in exchange for partnership
    units.................................................       --            --
  Withdrawal of partnership net assets upon conveyance of
    technology............................................       --           (176,642)
  Issuance of common stock for cash and short-term
    investments, $4.95 per share..........................       --          2,510,064
  Exercise of warrants for common stock...................       --             10,000
  Common stock subject to rescission......................       --           (901,200)
  Net loss................................................    (2,346,939)   (2,346,939)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1993..............................    (5,534,963)     (171,163)
  Issuance of common stock for cash, $4.95 per share......       --          2,797,818
  Exercise of warrants for common stock...................       --            122,100
  Issuance of common stock for consulting services, $4.95
    per share.............................................       --                749
  Unrealized gain on available-for-sale securities........       --             61,000
  Common stock subject to rescission......................       --           (170,078)
  Net loss................................................    (2,246,272)   (2,246,272)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1994..............................    (7,781,235)      394,154
  Issuance of common stock for cash, $6.00 per share......       --            862,689
  Compensation expense related to issuance of warrants for
    common stock..........................................       --            213,000
  Unrealized gain on available-for-sale securities........       --             35,750
  Net loss................................................    (2,556,886)   (2,556,886)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1995..............................   (10,338,121)   (1,051,293)
  Exercise of warrants for common stock...................       --            --
  Issuance of common stock for cash, $6.00 per share......       --          4,031,532
  Liquidation of available-for-sale securities............       --            (96,750)
  Net loss................................................    (2,087,362)   (2,087,362)
                                                            ------------  -------------
BALANCE AT DECEMBER 31, 1996..............................  $(12,425,483)  $   796,127
                                                            ------------  -------------
                                                            ------------  -------------
</TABLE>

 
                            See accompanying notes.
 
                                      F-7

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                            STATEMENTS OF CASH FLOWS
 

<TABLE>
<CAPTION>
                                                                                                  FOR THE PERIOD
                                                                     YEAR ENDED DECEMBER 31,       JULY 22, 1980
                                                                   ----------------------------   (INCEPTION) TO
                                                                       1995           1996       DECEMBER 31, 1996
                                                                   -------------  -------------  -----------------
<S>                                                                <C>            <C>            <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss.......................................................  $  (2,556,886) $  (2,087,362)  $   (12,425,483)
  Adjustments to reconcile net loss to net cash used in operating
    activities--
    Depreciation and amortization................................        503,340        520,300         2,061,438
    Realized gain on sale of short-term investments available for
      sale.......................................................       --              (96,750)          (96,750)
    Compensation expense on issuance of common stock and
      partnership units..........................................       --             --                 182,392
    Compensation expense on issuance of warrants to purchase
      common stock or partnership units..........................        213,000       --                 562,353
    Conversion of interest accrued to common stock...............       --             --                   7,860
  Changes in operating assets and liabilities:
    Decrease (increase) in other current assets..................          8,645        (21,019)          (28,255)
    Increase in other assets.....................................       --             --                 (45,191)
    Net increase in accounts payable, accrued payroll and
      deferred payments..........................................         53,318         76,743           334,570
                                                                   -------------  -------------  -----------------
      Net cash used in operating activities......................     (1,778,583)    (1,608,088)       (9,447,066)
                                                                   -------------  -------------  -----------------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Proceeds from sale or redemption of short-term investments.....         15,000        182,750           217,750
  Purchase of property and equipment.............................        (90,594)       (65,877)       (2,413,356)
  Patent costs...................................................       (177,989)       (66,870)         (642,959)
                                                                   -------------  -------------  -----------------
      Net cash (used in) provided by investing activities........       (253,583)        50,003        (2,838,565)
                                                                   -------------  -------------  -----------------
CASH FLOWS FROM FINANCING ACTIVITIES:
  Proceeds from sale of common stock and partnership units.......        862,689      4,031,532        15,536,612
  Withdrawal of partnership net assets...........................       --             --                (176,642)
  Issuance of convertible debt...................................       --             --                  80,000
  Deferred offering costs........................................       --             (143,110)         (143,110)
                                                                   -------------  -------------  -----------------
      Net cash provided by financing activities..................        862,689      3,888,422        15,296,860
                                                                   -------------  -------------  -----------------
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS.................     (1,169,477)     2,330,337         3,011,229
 
CASH AND CASH EQUIVALENTS:
  Beginning of period............................................      1,850,369        680,892         --
                                                                   -------------  -------------  -----------------
  End of period..................................................  $     680,892  $   3,011,229   $     3,011,229
                                                                   -------------  -------------  -----------------
                                                                   -------------  -------------  -----------------
</TABLE>

 
                              See accompanying notes.
 
                                      F-8

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                         NOTES TO FINANCIAL STATEMENTS
 
1. ORGANIZATION AND NATURE OF BUSINESS:
 
    ANTIVIRALS INC. (the Company) was incorporated in the State of Oregon on
July 22, 1980. The mission of the Company is to develop and commercialize
improved therapeutic products based upon antisense and drug delivery technology.
 
    Through May 1993, the financial statements include the combined accounts of
the Company and ANTI-GENE DEVELOPMENT GROUP, a limited partnership (AGDG or the
Partnership) founded in 1981 and registered in the State of Oregon.
Substantially all income generated and proceeds from the Partnership unit sales
have been paid to the Company under the terms of research and development
contracts entered into by the Partnership and the Company. Significant
transactions between the Company and the Partnership have been eliminated.
 
    In March 1993, the Company offered to all partners in the Partnership the
opportunity to exchange their partnership units or warrants to purchase
partnership units (unit warrants) for common stock or warrants to purchase
common stock. Under the terms of the offer, which was completed May 1, 1993,
each partner could elect to exchange each unit held or unit warrant held for
1,100 shares of common stock or warrants to purchase 1,100 shares of common
stock of the Company, respectively. One partner exchanged 325 partnership units
for warrants to purchase 357,500 shares of common stock. Total shares and
warrants to purchase shares issued in the exchange offer were 1,632,950 and
381,700, respectively.
 
    Effective May 19, 1993, the Company and the Partnership entered into a
Technology Transfer Agreement wherein the Partnership conveyed all intellectual
property in its control to the Company. As part of the conveyance, the Company
tendered to the Partnership for liquidation all partnership units received
pursuant to the exchange offer and received a 49.37 percent undivided interest
in the intellectual property. The Company then purchased the remaining undivided
interest in the intellectual property for rights to payments of 4.05 percent of
gross revenues in excess of $200 million, from sales of products which would, in
the absence of the Technology Transfer Agreement, infringe a valid claim under
any patent transferred to the Company.
 
    The remaining net assets of the Partnership, $176,642 of cash, were no
longer combined with those of the Company in May 1993. Under the terms of the
Technology Transfer Agreement, the Partnership ceased active sales of
partnership units and income generating activities and no longer will enter into
research and development contracts with the Company. The Partnership currently
exists primarily for the purpose of collecting potential future payments from
the Company as called for in the Technology Transfer Agreement.
 
    Beginning in 1991, the Company changed its fiscal year from a fiscal year
ending on October 31, to a calendar year. The new fiscal year was adopted
prospectively.
 
    In March 1996, the Company commenced a private offering wherein 712,500
shares of common stock were sold for net proceeds of $4,031,532, which included
warrants to purchase 60,201 shares of common stock at $9.00 per share. These
warrants are exercisable through the earlier of five years from issuance or
three years from the filing for an initial public offering.
 
    On October 3, 1996, the Board of Directors authorized management of the
Company to file a registration statement with the SEC offering to the public
1,500,000 units (the Units), each unit consisting of one share of the Company's
common stock, and one warrant to purchase one share of common stock.
 
                                      F-9

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
1. ORGANIZATION AND NATURE OF BUSINESS: (CONTINUED)
The Units will separate immediately following issuance and thereafter the common
stock and warrants that make up the Units will trade only as separate
securities.
 
    In November 1996, the shareholders approved a reverse split of the Company's
outstanding Common Stock on the basis of one share for each three shares of the
then-outstanding common stock. The share information in the accompanying
financial statements has been retroactively restated to reflect the reverse
split. The Common Stock will continue to have $.0001 par value. The shareholders
approved the authorization of a new class of preferred stock which includes
2,000,000 shares at $.0001 par value.
 
    The Company is in the development stage. Since its inception in 1980 through
December 31, 1996, the Company has incurred losses of approximately $12.4
million, substantially all of which resulted from expenditures related to
research and development and general and administrative expenses. The Company
has not generated any material revenue from product sales to date, and there can
be no assurance that revenues from product sales will be achieved. Moreover,
even if the Company does achieve revenues from product sales, the Company
nevertheless expects to incur operating losses over the next several years. The
financial statements have been prepared assuming that the Company will continue
as a going concern. The Company's ability to achieve a profitable level of
operations in the future will depend in large part on its completing product
development of its antisense and/or drug delivery products, obtaining regulatory
approvals for such products and bringing these products to market. During the
period required to develop these products, the Company will require substantial
financing. There is no assurance that such financing will be available when
needed or that the Company's planned products will be commercially successful.
If necessary, the Company's management will curtail expenditures in an effort to
conserve operating funds. The likelihood of the long-term success of the Company
must be considered in light of the expenses, difficulties and delays frequently
encountered in the development and commercialization of new pharmaceutical
products, competitive factors in the marketplace as well as the burdensome
regulatory environment in which the Company operates. There can be no assurance
that the Company will ever achieve significant revenues or profitable
operations.
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
 
USE OF ESTIMATES
 
    The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual results could differ from those estimates.
 
CASH AND CASH EQUIVALENTS
 
    The Company considers all highly liquid investments with an original
maturity of three months or less to be cash equivalents.
 
SHORT-TERM SECURITIES--AVAILABLE-FOR-SALE
 
    In January 1994, the Company adopted Statement of Financial Accounting
Standards No. 115, "Accounting for Certain Investments in Debt and Equity
Securities" (SFAS 115). In accordance with
 
                                      F-10

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
SFAS 115, the Company has classified its investment securities as
available-for-sale and, accordingly, such investment securities are stated on
the balance sheet at their fair market value, which approximated cost at
December 31, 1996 and exceeded cost by $96,750 at December 31, 1995. The
unrealized difference between the cost and the fair market value of these
securities has been reflected as a separate component of shareholders' equity.
These short-term securities included state government obligations with a cost,
which approximated fair market value, of $30,000 at December 31, 1995 and 1996
and common stock with a fair value of $182,750 at December 31, 1995.
 
PROPERTY AND EQUIPMENT
 
    Property and equipment is stated at cost and depreciated over the estimated
useful lives of the assets, generally five years, using the straight-line
method. Leasehold improvements are amortized over the shorter of the lease term
or the estimated useful life of the asset.
 
PATENT COSTS
 
    Patent costs consist primarily of legal and filing fees incurred to file
patents on proprietary technology developed by the Company. Patent costs are
amortized on a straight-line basis over the shorter of the estimated economic
lives or the legal lives of the patents, generally 17 years. Total accumulated
amortization at December 31, 1995 and 1996 was $127,000 and $168,000,
respectively.
 
RESEARCH AND DEVELOPMENT
 
    Research and development costs are expensed as incurred.
 
INCOME TAXES
 
    The Company accounts for income taxes, in accordance with Statement of
Financial Accounting Standards No. 109, "Accounting for Income Taxes" (SFAS
109). Under SFAS 109, deferred tax assets and liabilities are recorded based on
the tax effected difference between the tax bases of assets and liabilities and
their carrying amount for financial reporting purposes, referred to as temporary
differences, using enacted marginal income tax rates.
 
NET LOSS PER SHARE
 
    Net loss per share is calculated using the weighted average number of shares
outstanding. Common equivalent shares (stock options and warrants) are excluded
from the computation as their effect is antidilutive, except that, pursuant to
the Securities and Exchange Commission ("SEC") Staff Accounting Bulletins,
common and common equivalent shares issued during the period commencing 12
months prior to the initial filing of a proposed public offering at prices below
the public offering price have been considered in the calculation as if they
were outstanding for all periods presented (using the treasury stock method for
stock options and warrants at the estimated initial public offering price).
 
3. SHAREHOLDERS' EQUITY:
 
    At December 31, 1996, the Company had one stock option plan, the 1992 Stock
Incentive Plan (the Plan) which provides for the issuance of incentive stock
options to its employees and nonqualified stock
 
                                      F-11

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
3. SHAREHOLDERS' EQUITY: (CONTINUED)
options, stock appreciation rights and bonus rights to employees, directors of
the Company and consultants. The Company has reserved 1,333,333 shares of common
stock for issuance under the Plan. Options issued under the Plan generally vest
ratably over four years and expire five to ten years from the date of grant.
 
    During 1995, the Financial Accounting Standards Board issued SFAS 123, which
defines a fair value based method of accounting for an employee stock option and
similar equity instruments and encourages all entities to adopt that method of
accounting for all of their employee stock compensation plans. However, it also
allows an entity to continue to measure compensation cost for those plans using
the method of accounting prescribed by Accounting Principles Board Opinion No.
25 (APB 25). Entities electing to remain with the accounting in APB 25 must make
pro forma disclosures of net income and, if presented, earnings per share, as if
the fair value based method of accounting defined in SFAS 123 had been adopted.
The Company has elected to account for its stock-based compensation plans under
APB 25; however, the Company has computed, for pro forma disclosure purposes,
the value of all options granted during 1995 and 1996 using the Black-Scholes
options pricing model as prescribed by SFAS 123 using the following weighted
average assumptions for grants:
 

<TABLE>
<S>                                               <C>
Risk-free interest rate.........................      6%
Expected dividend yield.........................      0%
                                                    4 - 5
Expected lives..................................    Years
Expected volatility.............................     70%
</TABLE>

 
    Using the Black-Scholes methodology, the total value of options granted
during 1995 and 1996 was $431,582 and $148,866, respectively, which would be
amortized on a pro forma basis over the vesting period of the options (typically
four years). The weighted average fair value of options granted during 1995 and
1996 was $3.14 and $3.72, respectively. The value of warrants granted in 1995
and 1996 have not been considered as such warrant grants related to the raising
of additional equity.
 
    If the Company had accounted for its stock-based compensation plans in
accordance with SFAS 123, the Company's net income and net income per share
would approximate the pro forma disclosures below:
 

<TABLE>
<CAPTION>
                                                           FOR THE YEAR ENDED DECEMBER 31,
                                              ----------------------------------------------------------
                                                          1995                          1996
                                              ----------------------------  ----------------------------
                                               AS REPORTED     PRO FORMA     AS REPORTED     PRO FORMA
                                              -------------  -------------  -------------  -------------
<S>                                           <C>            <C>            <C>            <C>
Net loss....................................  $  (2,556,886) $  (2,810,494) $  (2,087,362) $  (2,185,676)
Net loss per share..........................          (0.37)         (0.40)         (0.25)         (0.27)
</TABLE>

 
    The effects of applying SFAS 123 in this pro forma disclosure are not
indicative of future amounts. SFAS 123 does not apply to awards prior to January
1, 1995, and additional awards are anticipated in future years.
 
                                      F-12

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
3. SHAREHOLDERS' EQUITY: (CONTINUED)
    A summary of the status of the Company's stock option plans and changes are
presented in the following table:
 

<TABLE>
<CAPTION>
                                                          FOR THE YEAR ENDED DECEMBER 31,
                                            ------------------------------------------------------------
                                                        1995                           1996
                                            -----------------------------  -----------------------------
                                                        WEIGHTED AVERAGE               WEIGHTED AVERAGE
                                              SHARES     EXERCISE PRICE      SHARES     EXERCISE PRICE
                                            ----------  -----------------  ----------  -----------------
<S>                                         <C>         <C>                <C>         <C>
Options outstanding at beginning of
  year....................................     977,148      $    4.65       1,109,828      $    4.71
Granted...................................     137,400           5.01          40,000           6.00
Exercised.................................      --             --              --             --
Canceled..................................       4,720           4.95          26,001           4.98
                                            ----------          -----      ----------          -----
Options outstanding at end of year........   1,109,828           4.71       1,123,827           4.75
                                            ----------          -----      ----------          -----
                                            ----------          -----      ----------          -----
Exercisable at end of year................     804,181      $    4.67         960,495      $    4.61
                                            ----------          -----      ----------          -----
                                            ----------          -----      ----------          -----
</TABLE>

 
    The following table sets forth the exercise price range, number of shares
outstanding at December 31, 1996, weighted average remaining contractual life,
weighted average exercise price, number of exercisable shares and weighted
average exercise price of exercisable options by groups of similar price and
grant date:
 

<TABLE>
<CAPTION>
                         OPTIONS OUTSTANDING
- ---------------------------------------------------------------------
               OUTSTANDING    WEIGHTED AVERAGE                              OPTIONS EXERCISABLE
                SHARES AT         REMAINING                            ------------------------------
  EXERCISE     DECEMBER 31,   CONTRACTUAL LIFE     WEIGHTED AVERAGE    EXERCISABLE  WEIGHTED AVERAGE
    PRICE          1996            (YEARS)          EXERCISE PRICE       OPTIONS     EXERCISE PRISE
- -------------  ------------  -------------------  -------------------  -----------  -----------------
<S>            <C>           <C>                  <C>                  <C>          <C>
    $4.56          790,901             5.45            $    4.56          724,236       $    4.56
     4.95          183,679             7.46                 4.95          127,012            4.95
     5.01           99,800             0.42                 5.01           99,800            5.01
     6.00           49,447             7.61                 6.00            9,447            6.00
</TABLE>

 
    The Company has also issued warrants for the purchase of common stock in
conjunction with financing and compensation arrangements. A summary of the
status of the Company's warrants and changes are presented in the following
table:
 

<TABLE>
<CAPTION>
                                                             YEAR ENDED DECEMBER 31,
                                         ---------------------------------------------------------------
                                                      1995                             1996
                                         -------------------------------  ------------------------------
                                                       WEIGHTED AVERAGE                 WEIGHTED AVERAGE
                                            SHARES      EXERCISE PRICE       SHARES      EXERCISE PRICE
                                         ------------  -----------------  ------------  ----------------
<S>                                      <C>           <C>                <C>           <C>
Warrants outstanding at beginning of
  year.................................     1,324,733      $    1.02         1,324,733     $     1.02
Granted................................        38,000           0.33            60,201           9.00
Exercised..............................       --              --               957,500         0.0003
Canceled...............................        38,000           0.33           --              --
                                         ------------          -----      ------------        -------
Warrants outstanding at end of year....     1,324,733           1.02           427,434           4.43
                                         ------------          -----      ------------        -------
                                         ------------          -----      ------------        -------
Exercisable at end of year.............     1,299,736      $    1.04           402,437     $     4.69
                                         ------------          -----      ------------        -------
                                         ------------          -----      ------------        -------
</TABLE>

 
                                      F-13

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
3. SHAREHOLDERS' EQUITY: (CONTINUED)
    The following table sets forth the exercise price range, number of shares
outstanding at December 31, 1996, weighted average remaining contractual life,
weighted average exercise price, number of exercisable shares and weighted
average exercise price of exercisable warrants by groups of similar price and
grant date:
 

<TABLE>
<CAPTION>
                      WARRANTS OUTSTANDING
- ----------------------------------------------------------------
               OUTSTANDING   WEIGHTED AVERAGE                         WARRANTS EXERCISABLE
                SHARES AT        REMAINING                        -----------------------------
  EXERCISE     DECEMBER 31,     CONTRACTUAL     WEIGHTED AVERAGE  EXERCISABLE  WEIGHTED AVERAGE
    PRICE          1996        LIFE (YEARS)      EXERCISE PRICE    WARRANTS     EXERCISE PRISE
- -------------  ------------  -----------------  ----------------  -----------  ----------------
<S>            <C>           <C>                <C>               <C>          <C>
  $  0.0003        124,799        Varies           $  0.0003          99,802      $  0.0003
     1.14           22,000        Varies              1.14            22,000         1.14
     4.56            1,100         5.75               4.56             1,100         4.56
     6.00          219,334        Varies              6.00           219,334         6.00
     9.00           60,201        Varies              9.00            60,201         9.00
</TABLE>

 
4. INCOME TAXES:
 
    At December 31, 1995 and 1996, the Company had federal and state tax net
operating loss carryforwards of approximately $7,731,000 and $9,410,000,
respectively. The difference between the operating loss carryforwards on a tax
basis and a book basis is due principally to differences in depreciation,
amortization, and treatment of research and development costs. The federal and
state carryforwards will begin to expire in 1997 and 2008, respectively, if not
otherwise used. The Internal Revenue Code rules under Section 382 could limit
the future use of these losses based on ownership changes in the value of the
Company's stock.
 
    The Company had a net deferred tax asset of $3,808,000 and $4,660,000 at
December 31, 1995 and 1996, primarily from net operating loss carryforwards. A
valuation allowance was recorded to reduce the net deferred tax asset to zero.
The net change in the valuation allowance for deferred tax assets was an
increase of approximately $1,195,000 and $852,000 for the years ended December
31, 1995 and 1996, respectively, mainly due to the increase in the net operating
loss carryforwards.
 
    An analysis of the deferred tax assets and liabilities as of December 31,
1995, is as follows:
 

<TABLE>
<CAPTION>
                                                               DEFERRED TAX  DEFERRED TAX
                                                                  ASSET       LIABILITY        TOTAL
                                                               ------------  ------------  -------------
<S>                                                            <C>           <C>           <C>
Net operating loss carryforwards.............................   $3,092,000    $   --       $   3,092,000
Accrued expenses.............................................      108,000        --             108,000
Depreciation.................................................      298,000        --             298,000
Research and development tax credit..........................      490,000        --             490,000
                                                               ------------  ------------  -------------
Patent costs.................................................       --          (180,000)       (180,000)
                                                               ------------  ------------  -------------
                                                                $3,988,000    $ (180,000)      3,808,000
                                                               ------------  ------------
                                                               ------------  ------------
Valuation allowance..........................................                                 (3,808,000)
                                                                                           -------------
                                                                                           $    --
                                                                                           -------------
                                                                                           -------------
</TABLE>

 
                                      F-14

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
4. INCOME TAXES: (CONTINUED)
    An analysis of the deferred tax assets and liabilities as of December 31,
1996, is as follows:
 

<TABLE>
<CAPTION>
                                                               DEFERRED TAX  DEFERRED TAX
                                                                  ASSET       LIABILITY        TOTAL
                                                               ------------  ------------  -------------
<S>                                                            <C>           <C>           <C>
Net operating loss carryforwards.............................   $3,764,000    $   --       $   3,764,000
Accrued expenses.............................................       23,000        --              23,000
Depreciation.................................................      403,000        --             403,000
Research and development tax credit..........................      660,000        --             660,000
Patent costs.................................................       --          (190,000)       (190,000)
                                                               ------------  ------------  -------------
                                                                $4,850,000    $ (190,000)      4,660,000
                                                               ------------  ------------
                                                               ------------  ------------
Valuation allowance..........................................                                 (4,660,000)
                                                                                           -------------
                                                                                           $    --
                                                                                           -------------
                                                                                           -------------
</TABLE>

 
5. LEASE OBLIGATIONS:
 
    The Company leases office and laboratory facilities under various
noncancelable operating leases through December 1997. Rent expense under these
leases was $168,000 and $193,000 for the years ended December 31, 1995 and 1996,
respectively, and $835,000 for the period from July 22, 1980 through December
31, 1996.
 
    In September 1996, the Company leased additional laboratory facilities and
extended the lease on its existing laboratory facilities through 2004. At
December 31, 1996, the aggregate noncancelable future minimum payments under
these leases were $288,000, $273,000, $258,000, $266,000 and $274,000 for the
years ended December 31, 1997, 1998, 1999, 2000 and 2001, respectively, and
$871,000 thereafter.
 
6. RELATED PARTY TRANSACTIONS:
 
    The Company paid $8,000, $12,000 and $233,000 to certain nonemployee
directors for financial consulting, scientific research services and
reimbursement for out-of-pocket costs of attending Board of Director meetings
during the years ended December 31, 1995 and 1996, and the period from July 22,
1980 through December 31, 1996, respectively.
 
7. SUBSEQUENT EVENTS:
 
    On January 20, 1997, AGDG and the Company amended the Technology Transfer
Agreement to reduce the Technology Fees arising from the sale of diagnostic
products from 4.05% to 2% and to remove the $200 million exemption with respect
to sales of such diagnostic products. The Company also granted to AGDG a
royalty-bearing license to make, use and sell small quantities of product
derived from the Intellectual Property for research purposes only.
 
    In 1997, as a condition to its planned initial public offering, the Company
intends to offer to holders of 1,292,973 shares of its common stock, the right
to rescind their purchase of shares of the Company's common stock. If all such
offerees elect to rescind their purchases, the Company will be required to pay
these shareholders $3,121,965 and 568.67 units of limited partnership interests
in AGDG, plus statutory interest. To the extent these shareholders accept the
rescission offer, the Company will use up to $1,500,000 of its cash resources to
repurchase the shares. If any additional consideration is required to
 
                                      F-15

<PAGE>
                                ANTIVIRALS INC.
                         (A DEVELOPMENT STAGE COMPANY)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
7. SUBSEQUENT EVENTS: (CONTINUED)
repurchase the shares, the Company will issue unsecured promissory notes to the
shareholders on a pro rata basis. Such notes will bear interest at 9% per annum
and mature between 18 and 36 months. If additional Partnership units are issued,
the fees arising from the sale of therapeutic products will be adjusted on a pro
rata basis, such that if all Partnership unit holders accept the rescission
offer, the fees for sales of therapeutic products will increase to approximately
5.25%. Fees related to diagnostic products under such a scenario would remain at
2%. The Company believes that its potential exposure to litigation for possible
past violations of securities laws will be effectively eliminated by this
rescission offer. All periods presented have been restated to reflect the amount
of common stock subject to the rescission offer outside of shareholders' equity.
 
    The Company estimates that the total amount of its obligation for interest
to rescinding shareholders could aggregate approximately $2,129,000 if all
eligible shareholders accepted the rescission offer. Because of the contingent
nature of such liability and because the ultimate amount to be refunded is not
presently known, the potential interest liability has not been accrued but will
be recorded as an expense of the Company if and when the amount becomes an
actual liability.
 
    The rescission offer will not be made to holders of 22,021 shares of common
stock in Florida as state securities laws do not permit such offerings. The
rescission offer will also not be made to holders of 192,603 shares of common
stock who reside in California and Nevada because the Company believes its
potential liability to these holders has been eliminated by the running of
applicable statute of limitations. If all the shareholders in Florida, Nevada
and California were to successfully assert claims against the Company, the
Company would be required to pay these holders approximately $319,000 and 55
units of limited partnership interests in AGDG, plus $237,000 in statutory
interest. Since no rescission offer has been made to these shareholders and
because of the contingent nature of such obligations, the potential liability
has not been reflected in the accompanying financial statements.
 
    The Company's cash flow and its financial position could be materially
affected by the results of the rescission offer. The financial statements do not
include any adjustments that might result from the outcome of the rescission
offer.
 
                                      F-16

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                         INDEX TO FINANCIAL STATEMENTS
 

<TABLE>
<S>                                                                                     <C>
R
eport of Independent Public Accountants..............................................        F-2
 
Balance Sheet as of December 31, 1996.................................................        F-3
 
Statements of Operations for the two years ended December 31, 1995 and 1996...........        F-4
 
Statements of Partners' Equity for the two years ended December 31, 1995 and 1996.....        F-5
 
Statements of Cash Flows for the two years ended December 31, 1995 and 1996...........        F-6
 
Notes to Financial Statements.........................................................        F-7

</TABLE>

 
                                      F-17

<PAGE>

                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
To the Partners of
ANTI-GENE DEVELOPMENT GROUP:
 
    We have audited the accompanying balance sheet of ANTI-GENE DEVELOPMENT
GROUP (an Oregon limited partnership) as of December 31, 1996, and the related
statements of operations, partners' capital and cash flows for the years ended
December 31, 1995 and 1996. These financial statements are the responsibility of
the Partnership's management. Our responsibility is to express an opinion on
these financial statements based on our audits.
 
    We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audits to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
    In our opinion, the financial statements referred to above present fairly,
in all material respects, the financial position of ANTI-GENE DEVELOPMENT GROUP
as of December 31, 1996, and the results of its operations and its cash flows
for the years ended December 31, 1995 and 1996 in conformity with generally
accepted accounting principles.
 
ARTHUR ANDERSEN LLP
 
Portland, Oregon,
March 14, 1997

 
                                      F-18

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                                 BALANCE SHEET
                            AS OF DECEMBER 31, 1996
 
                                     ASSETS
 

<TABLE>
<S>                                                         <C>
CURRENT ASSETS:
  Cash....................................................  $      1,988
  Certificates of deposit.................................       108,201
  Short-term investments--held to maturity................        78,595
                                                            ------------
      Total current assets................................       188,784
                                                            ------------
 
PROPERTY AND EQUIPMENT, at cost:
  Furniture and fixtures..................................           580
  Less--Accumulated depreciation..........................          (225)
                                                            ------------
                                                                     355
                                                            ------------
                                                            $    189,139
                                                            ------------
                                                            ------------
                           PARTNERS' CAPITAL
PARTNERS' CAPITAL.........................................  $    189,139
                                                            ------------
                                                            ------------
</TABLE>

 
                            See accompanying notes.
 
                                      F-19

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                            STATEMENTS OF OPERATIONS
 

<TABLE>
<CAPTION>
                                                                                                 YEAR ENDED DECEMBER
                                                                                                         31,
                                                                                                 --------------------
                                                                                                   1995       1996
                                                                                                 ---------  ---------
<S>                                                                                              <C>        <C>
REVENUES:
  Interest income..............................................................................  $   9,593  $   7,343
                                                                                                 ---------  ---------
 
EXPENSES:
  Insurance....................................................................................      2,035      2,035
  Accounting...................................................................................      1,250        845
  Miscellaneous................................................................................        819        235
                                                                                                 ---------  ---------
      Total expenses...........................................................................      4,104      3,115
                                                                                                 ---------  ---------
 
NET INCOME.....................................................................................  $   5,489  $   4,228
                                                                                                 ---------  ---------
                                                                                                 ---------  ---------
EARNINGS PER UNIT..............................................................................  $    2.96  $    2.28
                                                                                                 ---------  ---------
                                                                                                 ---------  ---------
WEIGHTED AVERAGE UNITS OUTSTANDING.............................................................      1,856      1,856
                                                                                                 ---------  ---------
                                                                                                 ---------  ---------
</TABLE>

 
                            See accompanying notes.
 
                                      F-20

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                        STATEMENTS OF PARTNERS' CAPITAL
 

<TABLE>
<CAPTION>
                                                                                                 UNITS      AMOUNT
                                                                                               ---------  ----------
<S>                                                                                            <C>        <C>
BALANCE, December 31, 1994...................................................................      1,856  $  184,882
  Add--Net income............................................................................     --           5,489
  Less--Partnership distributions............................................................     --          (2,784)
                                                                                               ---------  ----------
BALANCE, December 31, 1995...................................................................      1,856     187,587
  Add--Net income............................................................................     --           4,228
  Less--Partnership distributions............................................................     --          (2,676)
                                                                                               ---------  ----------
BALANCE, December 31, 1996...................................................................      1,856  $  189,139
                                                                                               ---------  ----------
                                                                                               ---------  ----------
</TABLE>

 
                            See accompanying notes.
 
                                      F-21

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                            STATEMENTS OF CASH FLOWS
 

<TABLE>
<CAPTION>
                                                                                          YEAR ENDED DECEMBER 31,
                                                                                          ------------------------
                                                                                             1995         1996
                                                                                          -----------  -----------
<S>                                                                                       <C>          <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net income............................................................................  $     5,489  $     4,228
  Adjustments to reconcile net income to net cash provided by operating
    activities--Depreciation and amortization...........................................      --               847
                                                                                          -----------  -----------
      Net cash provided by operating activities.........................................        5,489        5,075
                                                                                          -----------  -----------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Purchases of property and equipment...................................................         (497)     --
  Proceeds from redemption of certificates of deposit...................................      183,875      185,266
  Purchase of certificate of deposit....................................................     (185,971)    (108,201)
  Purchase of tax-exempt bonds..........................................................      --           (78,595)
                                                                                          -----------  -----------
      Net cash used by investing activities.............................................       (2,593)      (1,530)
                                                                                          -----------  -----------
CASH FLOWS FROM FINANCING ACTIVITIES:
  Partnership distributions.............................................................       (2,784)      (2,676)
                                                                                          -----------  -----------
INCREASE IN CASH........................................................................          112          869
CASH, beginning of period...............................................................        1,007        1,119
                                                                                          -----------  -----------
CASH, end of period.....................................................................  $     1,119  $     1,988
                                                                                          -----------  -----------
                                                                                          -----------  -----------
</TABLE>

 
                            See accompanying notes.
 
                                      F-22

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                         NOTES TO FINANCIAL STATEMENTS
 
1. ORGANIZATION AND NATURE OF BUSINESS:
 
    ANTI-GENE DEVELOPMENT GROUP (the Partnership), a limited partnership, was
founded in 1981 and registered in the State of Oregon. Through 1992,
substantially all proceeds from Partnership interest sales and interest income
had been paid to ANTIVIRALS INC. (the Company) under terms of research and
development contracts entered into by the Partnership and the Company. The
mission of the Company at that time, and as expanded today, is to develop and
commercialize improved therapeutic products based upon antisense and drug
delivery technology.
 
    In March 1993, the Company offered to all partners in the Partnership the
opportunity to exchange their partnership units or warrants to purchase
partnership units (unit warrants) for common stock or warrants to purchase
common stock. Under the terms of the offer, which was completed May 1, 1993,
each partner could elect to exchange each unit held or each unit warrant held
for 1,100 shares of common stock or warrants to purchase 1,100 shares of common
stock of the Company, respectively. One partner exchanged 325 partnership units
for warrants to purchase 357,500 shares of common stock. Total units exchanges
in the offer were 1,809.5.
 
    In February 1993, the Company and the Partnership entered into a Technology
Transfer Agreement wherein effective May 19, 1993, the Partnership conveyed all
intellectual property in its control to the Company. As part of the conveyance,
the Company tendered to the Partnership for liquidation all partnership units
received pursuant to the exchange offer and received a 49.37 percent undivided
interest in the intellectual property. The Company then purchased the remaining
undivided interest in the intellectual property for payments of 4.05 percent of
gross revenues in excess of $200 million, from sales of products which would, in
the absence of the Technology Transfer Agreement, infringe a valid claim under
any patent transferred to the Company.
 
    After the effective date of the Technology Transfer Agreement, the
Partnership ceased active sales of partnership units and no longer enters into
research and development contracts with the Company. The Partnership currently
exists for the purpose of collecting payments from the Company as called for in
the Technology Transfer Agreement.
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
 
USE OF ESTIMATES
 
    The preparation of financial statements in conformity with generally
accepted accounting principles requires estimates and assumptions that affect
the reported amounts of assets and liabilities and disclosure of contingent
assets and liabilities at the date of the financial statements and the reported
amounts of revenues and expenses during the reporting period. Actual results
could differ from those estimates.
 
SHORT-TERM INVESTMENTS--HELD-TO-MATURITY
 
    In January 1994, the Partnership adopted Statement of Financial Accounting
Standards No. 115, "Accounting for Certain Investments in Debt and Equity
Securities" (SFAS 115). In accordance with SFAS 115, the Partnership has
classified its investment securities as held-to-maturity and, accordingly, such
investment securities are stated on the balance sheet at their amortized cost.
Short-term investments at December 31, 1996 include a certificate of deposit
with a value of $108,201, state and local government obligations with an
amortized cost of $76,911, and a municipal money market fund with a value of
$1,684. Amortization of bond premium was $706 in 1996 and $0 in 1995.
 
                                      F-23

<PAGE>
                          ANTI-GENE DEVELOPMENT GROUP
                        (AN OREGON LIMITED PARTNERSHIP)
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
INCOME TAXES
 
    All tax effects of the Partnership's operations are passed through to the
partners individually. Accordingly, the accompanying financial statements
include no income tax expense for the Partnership.
 
3. SUBSEQUENT EVENTS:
 
    On January 20, 1997, the Partnership and the Company amended the Technology
Transfer Agreement to reduce the technology fees arising from the sale of
diagnostic products from 4.05 percent to 2 percent and to remove the $200
million exemption with respect to sales of such diagnostic products. The
Partnership also received a royalty-bearing license to make, use and sell
certain quantities of product derived from the intellectual property.
 
    In 1997, as a condition to its planned initial public offering, the Company
intends to offer to holders of 1,292,973 shares of its common stock, the right
to rescind their purchase of shares of the Company's common stock. If all such
offerees elect to rescind their purchases, the Company will be required to pay
these shareholders $3,121,965 and 568.67 units of limited partnership interests
in the Partnership, plus statutory interest. To the extent these shareholders
accept the rescission offer, the Company will use up to $1,500,000 of its cash
resources to repurchase the shares. If any additional consideration is required
to repurchase the shares, the Company will issue unsecured promissory notes to
the shareholders on a pro rata basis. Such notes will bear interest at 9% per
annum and mature between 18 and 36 months. If additional Partnership units are
issued, the fees arising from the sale of therapeutic products will be adjusted
on a pro rata basis, such that if all Partnership unit holders accept the
rescission offer, the fees for sales of therapeutic products will increase to
approximately 5.25%. Fees related to diagnostic products under such a scenario
would remain at 2%. The Company believes that its potential exposure to
litigation for possible past violations of securities laws will be effectively
eliminated by this rescission offer.
 
                                      F-24

<PAGE>
 
                                   PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
   
ITEM 20. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
    
 
    As an Oregon corporation the Company is subject to the Oregon Business
Corporation Act ("OBCA") and the exculpation from liability and indemnification
provisions contained therein. Pursuant to Section 60.047(2)(d) of the OBCA,
Article VI of the Company's Second Restated Articles of Incorporation (the
"Articles") eliminates the liability of the Company's directors to the Company
or its stockholders, except for any liability related to breach of the duty of
loyalty, actions not in good faith and certain other liabilities.
 
    Section 60.387 et seq. of the OBCA allows corporations to indemnify their
directors and officers against liability where the director or officer has acted
in good faith and with a reasonable belief that actions taken were in the best
interests of the corporation or at least not adverse to the corporation's best
interests and, if in a criminal proceeding, the individual had no reasonable
cause to believe the conduct in question was unlawful. Under the OBCA,
corporations may not indemnify against liability in connection with a claim by
or in the right of the corporation but may indemnify against the reasonable
expenses associated with such claims unless the party is adjusted liable to the
corporation. Corporations may not indemnify if the party is adjudged liable for
receiving improper personal benefit. The OBCA provides for mandatory
indemnification of directors against all reasonable expenses incurred in the
successful defense of any claim made or threatened whether or not such claim was
by or in the right of the corporation. Finally, a court may order
indemnification if it determines that the director or officer is fairly and
reasonably entitled to indemnification in view of all the relevant circumstances
whether or not the director or officer met the good faith and reasonable belief
standards of conduct set out in the statute.
 
    The OBCA also provides that the statutory indemnification provisions are not
deemed exclusive of any other rights to which directors or officers may be
entitled under a corporation's articles of incorporation or bylaws, any
agreement, general or specific action of the board of directors, vote of
stockholders or otherwise.
 
   
    Article VII of the Articles requires the Company to indemnify its directors
and officers to the fullest extent not prohibited by law. The Bylaws of the
Company also permit the Company to indemnify its directors and officers to the
fullest extent permitted by the OBCA.
    
 
   
ITEM 21. EXHIBITS.
    
 
(a) Exhibits
 

<TABLE>
<CAPTION>
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
<S>          <C>
       3.1   Third Restated Articles of Incorporation of AntiVirals Inc.(1)
 
       3.2   Bylaws of AntiVirals Inc.(1)
 
       3.3   Certificate of Limited Partnership of Anti-Gene Development Group
 
       4.1   Registration Rights Agreement between AntiVirals Inc. and Ice Bear, Inc., dated May 20, 1992(1)
 
       4.2   Purchase Warrants between AntiVirals and ORTDF, dated August 4, 1992(1)
 
       5.0   Opinion of Ater Wynne Hewitt Dodson & Skerritt, LLP as to the legality of the securities being
             registered(2)
 
      10.1   1992 Stock Incentive Plan(1)
 
      10.2   Employment Agreement with Denis R. Burger, Ph.D. dated November 4, 1996(1)
 
      10.3   Employment Agreement with James Summerton, Ph.D. dated November 4, 1996(1)
</TABLE>

 
                                      II-1

<PAGE>

<TABLE>
<CAPTION>
  NUMBER                                                   DESCRIPTION
- -----------  --------------------------------------------------------------------------------------------------------
      10.4   Employment Agreement with Alan P. Timmins dated November 4, 1996(1)
<S>          <C>
 
      10.5   Employment Agreement with Dwight Weller, Ph.D. dated November 4, 1996(1)
 
      10.6   Technology Transfer Agreement between Anti-Gene Development Group and AntiVirals Inc., dated February 9,
             1992(1)
 
      10.7   Amendment to Technology Transfer Agreement between Anti-Gene Development Group and AntiVirals Inc. dated
             January 20, 1997.(1)
 
      10.8   License and Option Agreement between Anti-Gene Development Group and AntiVirals Inc., dated February 9,
             1993.(1)
 
      10.9   Commercial Lease between Research Way Investments, Landlord, and AntiVirals Inc., Tenant, dated June 15,
             1992.(1)
 
      10.10  Lease between Benjamin Franklin Plaza, Inc., Landlord, and AntiVirals Inc., Tenant, dated June 17,
             1992.(1)
 
      10.11  First Amendment to lease between Benjamin Franklin Plaza, Inc., Landlord, and AntiVirals Inc., Tenant,
             dated July 24, 1995.(1)
 
      10.12  Pledge Agreement, dated       , 1997(2)
 
      23.1   Consent of Ater Wynne Hewitt Dodson & Skerritt, LLP (included in legal opinion filed as Exhibit 5.0)(2)
 
      23.2   Consent of Arthur Andersen LLP
 
      23.3   Consent of Peter Dehlinger & Associates(2)
 
      23.4   Consent of Arthur Andersen LLP
 
      25.0   Powers of Attorney (included in signature page in Part II of the Registration Statement)
</TABLE>

 
- ------------------------
 
(1) Filed as an Exhibit to the Company's Registration Statement on Form SB-2
    (Commission File No. 333-20513 and filed on January 28, 1996) and
    incorporated herein by reference.
 
(2) To be filed by amendment.
 
(b) Financial Statement Schedules
 
   
ITEM 22. UNDERTAKINGS.
    
 
    Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the provisions described in Item 24, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question of whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.
 
    The undersigned registrant hereby undertakes:
 
        1.  To file, during any period in which it offers or sells securities, a
    post-effective amendment to this registration statement to:
 
            (i) include any prospectus required by section 10(a)(3) of the
       Securities Act;
 
                                      II-2

<PAGE>
            (ii) reflect in the prospectus any facts or events which,
       individually or together, represent a fundamental change in the
       information set forth in the registration statement; and
 
           (iii) include any additional or changed material information on the
       plan of distribution.
 
        2.  That, for determining liability under the Securities Act, it will
    treat each post-effective amendment as a new registration statement of the
    securities offered, and the offering of the securities at that time to be
    the initial bona fide offering.
 
        3.  To file a post-effective amendment to remove from registration any
    of the securities that remain unsold at the end of the offering.
 
        4.  That, for determining any liability under the Securities Act, it
    will treat the information omitted from the form of prospectus filed as part
    of this registration statement in reliance upon Rule 430A and contained in a
    form of prospectus filed by the Company pursuant to Rule 424(b)(1) or (4) or
    497(h) under the Securities Act as part of this registration statement as of
    the time it was declared effective.
 
        5.  That, for determining any liability under the Securities Act, it
    will treat each post-effective amendment that contains a form of prospectus
    as a new registration statement for.the securities offered therein, and the
    offering of the securities at that time as the initial bona fide offering
    thereof.
 
   
        6.  The undersigned registrant hereby undertakes to respond to requests
    for information that is incorporated by reference into the prospectus
    pursuant to Item 4, 10(b), 11 or 13 of this form, within one business day of
    receipt of such request, and to send the incorporated documents by first
    class mail or other equally prompt means. This includes information
    contained in documents filed subsequent to the effective date of the
    registration statement through the date of responding to the request.
    
 
   
        7.  The undersigned registrant hereby undertakes to supply by means of a
    post-effective amendment all information concerning a transaction, and the
    company being acquired involved therein, that was not the subject of and
    included in the registration statement when it became effective.
    
 
                                      II-3

<PAGE>

                                   SIGNATURES
 
   
    In accordance with the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-4 and authorized this registration
statement to be signed on its behalf by the undersigned in the city of Portland,
state of Oregon, on April 21, 1997.
    
 

<TABLE>
<S>                             <C>  <C>
                                ANTIVIRALS INC.
 
                                By:             /s/ DENIS R. BURGER
                                     -----------------------------------------
                                                  Denis R. Burger,
                                              CHIEF EXECUTIVE OFFICER
</TABLE>

 
                               POWER OF ATTORNEY
 
    KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Denis R. Burger and Alan P. Timmins and each of
them singly, as true and lawful attorneys-in-fact and agents with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities to sign the Registration Statement filed herewith and any
or all amendments to said Registration Statement (including post-effective
amendments), and to file the same, with all exhibits thereto, and other
documents in connection therewith, with the Securities and Exchange Commission
granting unto said attorneys-in-fact and agents and full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the foregoing, as full to all intents and purposes as he or she
might or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or his substitute, may lawfully do
or cause to be done by virtue hereof.
 
    Witness our hands on the date set forth below.
 
   
    In accordance with the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the capacity
stated on April 21, 1997.
    
 

<TABLE>
<CAPTION>
          SIGNATURE                       TITLE
- ------------------------------  --------------------------
 
<C>                             <S>                         <C>
     /s/ DENIS R. BURGER        Chief Executive Officer
- ------------------------------    and Director (Principal
       Denis R. Burger            Executive Officer)
 
    /s/ JAMES E. SUMMERTON      President, Chief
- ------------------------------    Scientific Officer and
      James E. Summerton          Director
 
                                Chief Operating Officer
     /s/ ALAN P. TIMMINS          and Chief Financial
- ------------------------------    Officer (Principal
       Alan P. Timmins            Financial and Accounting
                                  Officer)
</TABLE>

 
                                      II-4

<PAGE>

<TABLE>
<CAPTION>
          SIGNATURE                       TITLE
- ------------------------------  --------------------------
 
<C>                             <S>                         <C>
     /s/ DWIGHT D. WELLER       Vice President of Research
- ------------------------------    and Development and
       Dwight D. Weller           Director
 
     /s/ JOHN A. BEAULIEU
- ------------------------------  Chairman of the Board
       John A. Beaulieu
 
       /s/ NICK BUNICK
- ------------------------------  Director
         Nick Bunick
 
      /s/ JAMES B. HICKS
- ------------------------------  Director
        James B. Hicks
 
    /s/ DONALD R. JOHNSON
- ------------------------------  Director
      Donald R. Johnson
 
    /s/ JAMES E. REINMUTH
- ------------------------------  Director
      James E. Reinmuth
 
     /s/ JOSEPH RUBINFELD
- ------------------------------  Director
       Joseph Rubinfeld
</TABLE>

 
                                      II-5

<PAGE>
                                   SIGNATURES
 
   
    In accordance with the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-4 and authorized this registration
statement to be signed on its behalf by the undersigned in the city of Portland,
state of Oregon, on April 21, 1997.
    
 

<TABLE>
<S>                             <C>  <C>
                                ANTI-GENE DEVELOPMENT GROUP,
                                A LIMITED PARTNERSHIP
 
                                By:            /s/ JAMES E. SUMMERTON
                                     -----------------------------------------
                                                James E. Summerton,
                                                  GENERAL PARTNER
</TABLE>

 
                                      II-6





<PAGE>
                       CERTIFICATE OF LIMITED PARTNERSHIP
                           RESTATED DECEMBER 31, 1994
 
    Due to the transfer exchange of partnership units the Certificate of Limited
Partnership of ANTI-GENE DEVELOPMENT GROUP is hereby restated:
 
   I.The name of the limited partnership is:
 
                             ANTI-GENE DEVELOPMENT GROUP
 
  II.The character of the business to be transacted is:
 
     development and commercialization of novel classes of compounds designed to
     bind selected genetic sequences and related technologies for diagnostic and
     therapeutic applications.
 
 III.The location of the principal place of business is at:
 
                                3107 NW Norwood Place
                               Corvallis, Oregon 97330
 
 IV. The address of its initial registered office in the State of Oregon is:
 
                                3107 NW Norwood Place
                               Corvallis, Oregon 97330
 
  V. The undersigned general partner designates the initial registered agent of
     the limited partnership and any successor registered agent as his personal
     registered agent and attorney upon whom any process, notice, or demand may
     be served which arises out of the conduct of the partnership affairs and
     which is required or permitted by law to be served upon a general partner.
 
 VI. The term for which the partnership is to exist is until December 31, 2018,
     unless sooner dissolved
 by consent of the general partner and a majority of
     the limited partners.
 
 VII.The name and residence of each member of the partnership and whether such
     member is a general or limited partner.
 

<TABLE>
<CAPTION>
               NAME                             RESIDENCE                GENERAL OR LIMITED
- -----------------------------------  --------------------------------  ----------------------
<S>                                  <C>                               <C>
Anderson, David                      220 SW Avery                             limited
                                     Corvallis, OR 97333
 
Anderson, Lawrence & Janet           21052 Winfield Road                      limited
                                     Topanga, CA 90290
 
Ball, Peter                          2805 SW Fairmont Dr.                     limited
                                     Corvallis, OR 97333
 
Bartley & Starns                     2705 NW Glenwood Dr.                     limited
                                     Corvallis, OR 97330
 
Blackledge & Blackledge              PO Box 639                               limited
                                     Corvallis, OR 97339
 
Brajcich, Douglas                    West 601 Main, Suite 812                 limited
                                     Spokane, WA 99201
 
Brunner & Johnson                    2486 NE Dutch Vista #3                   limited
                                     Canby, OR 97013
 
Buchanan, Deanna                     PO Box 3205                              limited
                                     Friday Harbor, WA 98250
</TABLE>

 
                                       1

<PAGE>

<TABLE>
<CAPTION>
               NAME                             RESIDENCE                GENERAL OR LIMITED
- -----------------------------------  --------------------------------  ----------------------
<S>                                  <C>                               <C>
Buchanan & Buchanan                  1146 NW Alder Creek Dr.                  limited
                                     Corvallis, OR 97330
 
Buchanan, William                    1125 Bay Blvd.                           limited
                                     Newport, OR 97365
 
Dehlinger & Dehlinger                58 Roosevelt Circle                      limited
                                     Palo Alto, CA 94306
 
Einwaller, Chris                     10001 SW 25th Ave.                       limited
                                     Portland, OR 97219
 
Einwaller, Peter                     10001 SW 25th Ave.                       limited
                                     Portland, OR 97219
 
Einwaller, Tony                      295 Pond Lane                            limited
                                     Bow, WA 98232
 
Epplett, Louis                       815 Brookside Drive                      limited
                                     Eugene, OR 97405
 
Farrell, Pamela                      130 E. 38th Avenue                       limited
                                     Eugene, OR 97405
 
Fishler & Fishler                    9704 Cedar Crest Drive                   limited
                                     Sandy, UT 84092
 
Foster, Ernest                       1694 SW Squaw Creek Pl.                  limited
                                     Corvallis, OR 97333
 
Gehring, Byron                       4816 Cypress Ford Dr.                    limited
                                     Fuguay Vanna, NC 27526
 
Hall, Clifford                       7505 NW Hoodview Dr.                     limited
                                     Corvallis, OR 97330
 
Hare, Michael                        1601 SW Brooklane Drive                  limited
Pacific NW Trust Co., Cust.          Corvallis, OR 97333
FBO Salem Emerg Phys., Cust.
 
Harvey, Charles                      PO Box 1525                              limited
                                     Blythe, CA 92226
 
Hensley-Jones, Constance             774 SW Lookout Dr.                       limited
                                     Corvallis, OR 97333
 
Henderson & Pehkonen                 2007 Morningside Drive                   limited
                                     Florence, KY 41042
 
Heying, C. Stephen                   514 Redbud Lane                          limited
                                     Ashland, MO 65010
 
Hoard, Lott & Caldwell               307 Sunset Ave.                          limited
                                     Huntsville, AL 35801
 
Houghtaling & Houghtaling            2630 SW McGinnis Ave.                    limited
                                     Troudale, OR 97060
 
Ito & Ito                            3844 NW Jameson Dr.                      limited
                                     Corvallis, OR 97330
 
Johnson, Arnett                      8115 Sacajawea Way N.                    limited
                                     Wilsonville, OR 97070
</TABLE>

 
                                       2

<PAGE>

<TABLE>
<CAPTION>
               NAME                             RESIDENCE                GENERAL OR LIMITED
- -----------------------------------  --------------------------------  ----------------------
<S>                                  <C>                               <C>
Johnson, Donald                      1005 South Hilton Rd.                    limited
                                     Wilmington, DE 19803
 
Johnson C. & Johnson S.              1265 NW Heather Dr.                      limited
                                     Corvallis, OR 97330
 
Johnson K. & Johnson L.              2929 NW Highland                         limited
                                     Corvallis, OR 97330
 
Johnson M. & Johnson K.              4721 NW Virginia Place                   limited
                                     Corvallis, OR 97330
 
Kaiser, Henry                        14040 Kings Valley Hwy                   limited
                                     Monmouth, OR 97361
 
Koopman, Dirk                        5745 SW Arrowwood Lane                   limited
                                     Portland, OR 97225
 
Kraft & Kraft, Henry                 6508 Pontiac Drive                       limited
                                     Indian Head Park, IL 60525
 
Kraft & Kraft, Walter                2900 NE Pilkington Dr.                   limited
                                     Corvallis, OR 97330
 
Larpenteur, James A.                 1211 SW 5th, Suite 1800                  limited
                                     Portland, OR 97204
 
Latimer/Tabor Family Trust           7220 NE Logsdon Road                     limited
                                     Corvallis, OR 97330
 
Magee, Thomas & Joseph               9905 S. Damen Ave.                       limited
                                     Chicago, IL 60643
 
Malone, Kristeen                     3602 NW 135th Circle                     limited
                                     Vancouver, WA 98685
 
Mathews & Mathews                    3336 SW Willamette                       limited
                                     Corvallis, OR 97333
 
Novak & Novak                        14750 SW Bonanza Ct.                     limited
                                     Beaverton, OR 97007
 
Oregon Resource and                  4370 NE Halsey, Suite 233                limited
Technology Development Fund          Portland, OR 97213
 
Pyle, Jane                           3955 SW Brooklane Dr.                    limited
Revocable Living Trust               Corvallis, OR 97333
 
Pyle, Scotty                         3955 SW Brooklane Dr.                    limited
Revocable Living Trust               Corvallis, OR 97333
 
Rarick, et al.                       13 Pinto Lane                            limited
                                     Rolling Hills Est., CA 90274
 
Rarick, Wanda & Rose                 834 2nd St., Apt. 1 & 6                  limited
                                     Santa Monica, CA 90403
 
Reynolds, Kathryn                    PO Box 8317                              limited
                                     Black Butte Ranch OR 97759
 
Reynolds & Reynolds                  3293 NW Tanager Dr.                      limited
                                     Corvallis, OR 97330
</TABLE>

 
                                       3

<PAGE>

<TABLE>
<CAPTION>
               NAME                             RESIDENCE                GENERAL OR LIMITED
- -----------------------------------  --------------------------------  ----------------------
<S>                                  <C>                               <C>
Rose, Mark                           17824 SE Alder                           limited
                                     Portland, OR 97233
 
Schmidt & Schmidt                    7929 SE Duke St.                         limited
                                     Portland, OR 97206
 
Small, Enoch                         S. 6805 Tomaker Lane                     limited
                                     Spokane, WA 99223
 
Starns, Selma                        2705 NW Glenwood Dr.                     limited
                                     Corvallis, OR 97330
 
Summerton, James E.                  3107 NW Norwood Place                    general
                                     Corvallis, OR 97330
 
Summerton, Patricia                  3107 NW Norwood Place                    limited
                                     Corvallis, OR 97330
 
Timmins, Alan                        29290 SW Ladd Hill Road                  limited
                                     Sherwood, OR 97140
 
Weatherford, Marion                  Olex Rural Route Box 44                  limited
                                     Arlington, OR 97812
 
Weller & Weller                      3323 NW Elmwood                          limited
                                     Corvallis, OR 97330
 
Wildish, Forona                      455 Alexander Loop #137                  limited
                                     Eugene, OR 97401
 
Winner, Dennis                       1905 SW Custer                           limited
                                     Portland, OR 97219
 
Held as:                             121 SW Morrison, Suite 1450              limited
Enele and Co.                        Portland, OR 97204
Cust. FBO
Dennis D. Winner, MD
Keogh #4804
</TABLE>

 
 VIII.
     The additional contributions of cash or property, if any, agreed to be made
     by each partner: NONE!
 
 IX. In the event the general partner concludes there are insurmountable
     difficulties preventing further development or commercialization of the
     partnership's inventions and patents, any uncommitted partnership funds and
     other assets, or proceeds from liquidation thereof, will be returned to the
     partners pro rata to their partnership interests.
 
  X. The share of the profits and losses which each partner shall receive by
     reason of his proportional ownership shall be:
 
    Losses, up to the amount invested, will be allocated yearly in direct
proportion to the amount of capital each partner has invested during that year,
or during that phase if the phase is less than one year. Losses will be
calculated on a first-in first-out basis. Any additional losses will be
allocated pro rata to all partnership interests.
 
    Profits will be distributed pro rata to all partnership interests.
 
                                       4

<PAGE>
 

<TABLE>
<CAPTION>
                                                                                NUMBER OF
NAME                                                                            INTERESTS
- --------------------------------------------------------------------------  ------------------
<S>                                                                         <C>
Anderson, David...........................................................      6
Anderson, Lawrence & Janet................................................      1
Ball, Peter...............................................................      1
Bartley & Starns..........................................................      20
Blackledge & Blackledge...................................................      43
Brajcich, Douglas.........................................................      .5
Brunner & Johnson.........................................................      2
Buchanan, Deanna..........................................................      4
Buchanan & Buchanan.......................................................      .5
Buchanan, William.........................................................      .5
Dehlinger & Dehlinger.....................................................      5
Einwaller, Chris..........................................................      1
Einwaller, Peter..........................................................      1
Einwaller, Tony...........................................................      1
Epplett, Louis............................................................      4
Farrell, Pamela...........................................................      1
Fishler & Fishler.........................................................      1
Foster, Ernest............................................................      6
Gehring, Byron............................................................      2
Hall, Clifford............................................................      .25
Hare, Michael.............................................................      1
Harvey, Charles...........................................................      1
Hensley-Jones, Constance..................................................      2
Henderson & Pehkonen......................................................      2
Heying, C. Stephen........................................................      1
Hoard, Lott & Caldwell....................................................      1
Houghtaling & Houghtaling.................................................      1
Ito & Ito.................................................................      1
Johnson, Arnett...........................................................      5
Johnson, Donald...........................................................      10
Johnson C. & Johnson S....................................................      1
Johnson K. & Johnson L....................................................      8
Johnson M. & Johnson K....................................................      6
Kaiser, Henry.............................................................      10
Koopman, Dirk.............................................................      1
Kraft & Kraft, Henry......................................................      10
Kraft & Kraft, Walter.....................................................      5
Larpenteur, James.........................................................      5
Latimer/Tabor Family Trust................................................      .25
Magee, Thomas & Joseph....................................................      1
Malone, Kristeen..........................................................      1
Mathews & Mathews.........................................................      10.5
Novak & Novak.............................................................      1
Oregon Resource & Tech. Dev. Fund.........................................      36
Pyle, Jane Revocable Living Trust.........................................      2
Pyle, Scotty Revocable....................................................
Living Trust..............................................................      2
Rarick, et al.............................................................      1
Rarick, Wanda & Rose......................................................      .5
Reynolds, Kathryn.........................................................      5
</TABLE>

 
                                       5

<PAGE>

<TABLE>
<CAPTION>
                                                                                NUMBER OF
NAME                                                                            INTERESTS
- --------------------------------------------------------------------------  ------------------
<S>                                                                         <C>
Reynolds & Reynolds.......................................................      .5
Rose, Mark................................................................      .5
Schmidt & Schmidt.........................................................      2
Small, Enoch..............................................................      2
Starns, Selma.............................................................      10
Summerton, James E........................................................      1,422
Summerton, Patricia.......................................................      52
Timmins, Alan.............................................................      2
Weatherford, Marion.......................................................      2
Weller & Weller...........................................................      80
Wildish, Leonard A. Family................................................
Trust #1..................................................................      50
Winner, Dennis............................................................      1
    Total interests.......................................................      1,856
</TABLE>

 
 XI. The right of a partner to substitute an assignee as partner in his place
     and the terms and conditions of that substitution are:
 
    Any partner is free to assign his interest or interests in the partnership
unless the general partner concludes that such an assignment when added to
previous assignments within the previous 12 months would jeopardize the tax
status of the partnership.
 
 XII.Rights to admit additional limited partners are as follows: The general
     partner has the right to admit additional limited partners and the right to
     exercise a power of attorney to sign on behalf of the limited partners an
     amendment to this certificate--but only for the purpose of adding new
     limited partners, deleting retiring partners, or effecting partnership
     transfers.
 
 XIII.
     No right is given for one or more of the partners to have priority over
     other partners as to contributions or as to compensation by way of income,
     aside from that detailed in section X.
 
XIV. Rights to continue the business on the death, insanity, or retirement of
     the general partner are as follows:
 
    In the event of the death, insanity or retirement of the general partner,
the partners shall elect by majority vote either to continue the partnership
with a new general partner or to dissolve the partnership and distribute the
assets pro rata to their interests with one vote corresponding to each
partnership interest. Any selection of a new general partner shall be carried
out by majority election with one vote corresponding to each partnership
interest.
 
 XV. The right of a partner to demand and receive property other than cash in
     return for his contribution is as follows:
 
    No compensation other than that detailed in sections IX, X, and XIV of this
certificate shall accrue to partners.
 
XVI. The right of a limited partner to vote upon matters affecting the basic
     structure of the partnership is as follows:
 
    Limited partners may vote to dissolve the partnership prior to its planned
termination date. Consent of a majority of the limited partners plus the general
partner will constitute grounds for early dissolution.
 
                                       6



<PAGE>
                                                                    EXHIBIT 23.2
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   
    As independent public accountants, we hereby consent to the use of our
reports dated March 10, 1997, relating to the financial statements of AntiVirals
Inc. and to all references to our firm included in Amendment No. 2 to
Registration Statement on Form SB-2 on Form S-4 (No. 333-20511) of AntiVirals
Inc.
    
 
                                          ARTHUR ANDERSEN LLP
 
   
Portland, Oregon,
April 22, 1997
    





<PAGE>
                                                                    EXHIBIT 23.4
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
   
    As independent public accountants, we hereby consent to the use of our
reports dated March 14, 1997, relating to the financial statements of Anti-Gene
Development Group, and to all references to our firm included in Amendment No. 2
to Registration Statement on Form SB-2 on Form S-4 (No. 333-20511) of AntiVirals
Inc.
    
 
                                          ARTHUR ANDERSEN LLP
 
   
Portland, Oregon,
April 22, 1997