0001564590-21-024018 | 10-Q | XBRL Viewer

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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Trading Symbol	SRPT
Entity Registrant Name	Sarepta Therapeutics, Inc.
Entity Central Index Key	0000873303
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		79,774,575
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-14895
Entity Tax Identification Number	93-0797222
Entity Address, Address Line One	215 First Street
Entity Address, Address Line Two	Suite 415
Entity Address, State or Province	MA
Entity Address, City or Town	Cambridge
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	274-4000
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,481,836	$ 1,502,648
Short-term investments	255,997	435,923
Accounts receivable	118,203	101,340
Inventory	240,333	231,961
Other current assets	174,981	213,324
Total current assets	2,271,350	2,485,196
Property and equipment, net	203,107	190,430
Intangible assets, net	14,124	13,628
Right of use assets	65,068	91,761
Other non-current assets	211,584	203,703
Total assets	2,765,233	2,984,718
Current liabilities:
Accounts payable	76,651	111,090
Accrued expenses	180,636	193,553
Deferred revenue, current portion	89,244	89,244
Other current liabilities	18,205	22,139
Total current liabilities	364,736	416,026
Long-term debt	1,091,110	992,493
Lease liabilities, net of current portion	60,675	80,367
Deferred revenue, net of current portion	641,483	663,488
Contingent consideration	50,800	50,800
Other non-current liabilities	20,984	19,785
Total liabilities	2,229,788	2,222,959
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 3,333,333 shares authorized; none issued and outstanding
Common stock, $0.0001 par value, 198,000,000 shares authorized; 79,748,109 and 79,374,247 issued and outstanding at March 31, 2021, and December 31, 2020, respectively	8	8
Additional paid-in capital	3,490,658	3,609,877
Accumulated other comprehensive (loss) income, net of tax	(3)	3
Accumulated deficit	(2,955,218)	(2,848,129)
Total stockholders’ equity	535,445	761,759
Total liabilities and stockholders’ equity	$ 2,765,233	$ 2,984,718

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	3,333,333	3,333,333
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	198,000,000	198,000,000
Common stock, issued	79,748,109	79,374,247
Common stock, outstanding	79,748,109	79,374,247

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Products, net	$ 124,926	$ 100,448
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember
Collaboration	$ 22,005	$ 13,226
Total revenues	146,931	113,674
Cost and expenses:
Cost of sales (excluding amortization of in-licensed rights)	22,346	12,622
Research and development	195,149	136,144
Selling, general and administrative	71,131	82,768
Settlement and license charges	10,000
Amortization of in-licensed rights	170	166
Total cost and expenses	298,796	231,700
Operating loss	(151,865)	(118,026)
Other (loss) income:
Other expense, net	(15,528)	(7,420)
Gain from sale of Priority Review Voucher		108,069
Total other (loss) income	(15,528)	100,649
Loss before income tax (benefit) expense	(167,393)	(17,377)
Income tax (benefit) expense	(143)	115
Net loss	(167,250)	(17,492)
Other comprehensive (loss) income:
Unrealized (losses) gains on investments, net of tax	(6)	574
Total other comprehensive (loss) income	(6)	574
Comprehensive loss	$ (167,256)	$ (16,918)
Net loss per share - basic and diluted	$ (2.10)	$ (0.23)
Weighted average number of shares of common stock used in computing basic and diluted net loss per share	79,454	76,432

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect of Accounting Change [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Cumulative Effect of Accounting Change [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Cumulative Effect of Accounting Change [Member]
Balance at Dec. 31, 2019	$ 818,187		$ 8	$ 3,112,130		$ 50	$ (2,294,001)
Balance (in shares) at Dec. 31, 2019			75,185,000
Exercise of options for common stock	3,687			3,687
Exercise of options for common stock, shares			97,000
Vest of restricted stock units			98
Issuance of common stock to Roche, net ofissuance costs	312,053			312,053
Issuance of common stock to Roche, net of issuance costs, shares			2,522
Issuance of common stock under employee stock purchase plan	3,795			3,795
Issuance of common stock under employee stock purchase plan, shares			56,000
Stock-based compensation	24,024			24,024
Unrealized gains (losses) from available-for-sale securities, net of tax	574					574
Net loss	(17,492)						(17,492)
Balance at Mar. 31, 2020	1,144,828		$ 8	3,455,689		624	(2,311,493)
Balance (in shares) at Mar. 31, 2020			77,958,000
Balance at Dec. 31, 2020	761,759	$ (96,792)	$ 8	3,609,877	$ (156,953)	3	(2,848,129)	$ 60,161
Balance (in shares) at Dec. 31, 2020			79,374,000
Exercise of options for common stock	4,683			4,683
Exercise of options for common stock, shares			108,000
Vest of restricted stock units			204,000
Issuance of common stock under employee stock purchase plan	4,543			4,543
Issuance of common stock under employee stock purchase plan, shares			62,000
Stock-based compensation	28,508			28,508
Unrealized gains (losses) from available-for-sale securities, net of tax	(6)					(6)
Net loss	(167,250)						(167,250)
Balance at Mar. 31, 2021	$ 535,445		$ 8	$ 3,490,658		$ (3)	$ (2,955,218)
Balance (in shares) at Mar. 31, 2021			79,748,000

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (167,250)	$ (17,492)
Adjustments to reconcile net loss to cash flows from operating activities:
Depreciation and amortization	8,930	6,529
Reduction in the carrying amounts of the right of use assets	2,220	2,153
Amortization of investment discount	(82)	(1,284)
Non-cash interest expense	1,816	6,342
Stock-based compensation	28,508	24,024
Gain from sale of Priority Review Voucher, net of commission		(108,069)
Other	2,774	(1,381)
Changes in operating assets and liabilities, net:
Net increase in accounts receivable	(16,863)	(15,996)
Net increase in inventory	(8,372)	(1,789)
Net decrease (increase) in other assets	(34,915)	27,966
Net (decrease) increase in deferred revenue	(22,005)	820,437
Net decrease in accounts payable, accrued expenses and other liabilities	(44,962)	(57,718)
Net cash (used in) provided by operating activities	(180,371)	627,790
Cash flows from investing activities:
Purchase of property and equipment	(21,149)	(9,120)
Purchase of available-for-sale securities	(29,989)	(365,437)
Maturity and sale of available-for-sale securities	210,000	250,000
Proceeds from sale of Priority Review Voucher, net of commission		108,069
Other	(2,196)	(1,192)
Net cash provided by (used in) investing activities	156,666	(17,680)
Cash flows from financing activities:
Proceeds from exercise of stock options and purchase of stock under the Employee Stock Purchase Program	9,226	7,482
Taxes paid related to net share settlement of equity awards	(6,333)	(4,798)
Net cash provided by financing activities	2,893	319,022
(Decrease) increase in cash, cash equivalents and restricted cash	(20,812)	929,132
Cash, cash equivalents and restricted cash:
Beginning of period	1,511,713	843,645
End of period	1,490,901	1,772,777
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	1,481,836	1,764,212
Restricted cash in other assets	$ 9,065	$ 8,565
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Total cash, cash equivalents and restricted cash	$ 1,490,901	$ 1,772,777
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	11,688	5,385
Supplemental schedule of non-cash investing activities and financing activities:
Intangible assets and property and equipment included in accrued expenses	5,729	6,154
Lease liabilities arising from obtaining right of use assets	901	24,783
Lease liabilities terminated	$ 19,967
Issuance costs related to the Roche Collaboration in accrued expenses		4,285
Roche
Cash flows from financing activities:
Proceeds from issuance of common stock to Roche, net of offering costs		$ 316,338

ORGANIZATION AND NATURE OF BUSINESS

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

ORGANIZATION AND NATURE OF BUSINESS

1. ORGANIZATION AND NATURE OF BUSINESS

Sarepta Therapeutics, Inc. (together with its wholly-owned subsidiaries, “Sarepta” or the “Company”) is a commercial-stage biopharmaceutical company focused on helping patients through the discovery and development of unique RNA-targeted therapeutics, gene therapy and other genetic therapeutic modalities for the treatment of rare diseases. Applying its proprietary, highly-differentiated and innovative technologies, and through collaborations with its strategic partners, the Company is developing potential therapeutic candidates for a broad range of diseases and disorders, including Duchenne muscular dystrophy (“DMD”), Limb-girdle muscular dystrophies (“LGMDs”), and other neuromuscular and central nervous system (“CNS”) related disorders.

Its products in the U.S., EXONDYS 51 (eteplirsen) Injection (“EXONDYS 51”), VYONDYS 53 (golodirsen) Injection (“VYONDYS 53”) and AMONDYS 45 (casimersen) Injection (“AMONDYS 45”), were granted accelerated approval by the U.S. Food and Drug Administration (the “FDA”) on September 19, 2016, December 12, 2019 and February 25, 2021, respectively. EXONDYS 51, VYONDYS 53 and AMONDYS 45 are indicated for the treatment of DMD in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51, exon 53 and exon 45 skipping, respectively. EXONDYS 51, VYONDYS 53 and AMONDYS 45 use the Company’s phosphorodiamidate morpholino oligomer (“PMO”) chemistry and exon-skipping technology to skip exon 51, exon 53 and exon 45, respectively, of the dystrophin gene. Exon skipping is intended to promote the production of an internally truncated but functional dystrophin protein.

As of March 31, 2021, the Company had approximately $1,747.1 million of cash, cash equivalents and investments, consisting of $1,481.8 million of cash and cash equivalents, $256.0 million of short-term investments, and $9.3 million of long-term restricted cash and investments. The Company believes that its balance of cash, cash equivalents and investments as of the date of the issuance of this report is sufficient to fund its current operational plan for at least the next twelve months, though it may pursue raising additional cash resources through public or private debt and equity financings, seek additional government contracts and establish collaborations with or license its technology to other companies.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), reflect the accounts of Sarepta and its wholly-owned subsidiaries. All intercompany transactions between and among its consolidated subsidiaries have been eliminated. Management has determined that the Company operates in one segment: discovering, developing, manufacturing and delivering therapies to patients with rare diseases.

In the opinion of the Company’s management, all adjustments of a normal recurring nature necessary for a fair presentation have been reflected. Certain financial information that is normally included in annual financial statements prepared in accordance with the U.S. GAAP, but that is not required for interim reporting purposes, has been omitted. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2020 which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the U.S. Securities and Exchange Commission on March 1, 2021. The results for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the full year.

Estimates and Uncertainties

The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist of accounts receivable from customers, cash held at financial institutions and cash equivalents and investments.

As of March 31, 2021, the majority of the Company’s accounts receivable arose from product sales in the U.S. and all customers have standard payment terms that generally require payment within 60 to 91 days. Outside of the U.S., the majority of the Company’s customers have payment terms ranging between 45 and 150 days. Three individual customers accounted for 49%, 40 % and 7% of net product revenues for the three months ended March 31, 2021 and 44%, 40 % and 12% of net product revenues for the three months ended March 31, 2020. Three individual customers accounted for 49%, 40% and 7% of accounts receivable from product sales as of March 31, 2021 and 45%, 41% and 9% of accounts receivable from product sales as of December 31, 2020. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in its customers’ credit profile. As of March 31, 2021, the Company believes that such customers are of high credit quality.

As of March 31, 2021, the Company’s cash was concentrated at three financial institutions in the U.S., which potentially exposes the Company to credit risks. However, the Company does not believe that there is significant risk of non-performance by the financial institutions.

Significant Accounting Policies

For details about the Company’s accounting policies, please read Note 2, Summary of Significant Accounting Policies and Recent Accounting Pronouncements of the Annual Report on Form 10-K for the year ended December 31, 2020.

There have not been any material changes to the Company’s accounting policies through March 31, 2021, other than those noted below relating to the adoption of ASU 2020-06, “Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity.”

Recent Accounting Pronouncements

Recently adopted

In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-06, “Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity.” This ASU simplifies the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. More specifically, the amendments focus on the guidance for convertible instruments and derivative scope exceptions for contracts in an entity’s own equity. Under ASU 2020-06, the embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives under Topic 815, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument, such as the Company’s senior notes due on November 15, 2024 (the “2024 Notes”), will be accounted for as a single liability measured at its amortized cost, as long as no other features require bifurcation and recognition as derivatives. The new guidance also requires the if-converted method to be applied for all convertible instruments and requires additional disclosures. This guidance is required to be adopted by January 1, 2022, and early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020.

The Company has elected to early adopt this guidance on January 1, 2021, using the modified retrospective method. Under this transition method, the cumulative effect of the accounting change removed the impact of recognizing the equity component of the Company’s convertible notes (at issuance and the subsequent accounting impact of additional interest expense from debt discount amortization). The cumulative effect of the accounting change as of January 1, 2021 increased the carrying amount of the convertible notes by $96.8 million, reduced accumulated deficit by $60.2 million and reduced additional paid-in capital by $157.0 million. Interest expense of the 2024 Notes will be lower as a result of adoption of this guidance. The if-converted method for such instruments will be used to compute diluted net earnings per share if and when profitability is achieved. As a result of the adoption of this guidance, interest expense and net loss was reduced by $5.4 million for the three months ended March 31, 2021, which was $0.07 per share.

In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”, which is intended to simplify the accounting for income taxes. This ASU removes certain exceptions to the general principles in Topic 740 and clarifies and amends existing guidance to improve consistent application. The new guidance was effective beginning January 1, 2021. The adoption of this guidance did not have a material effect on the Company’s consolidated financial statements.

LICENSE AND COLLABORATION AGREEMENTS

3 Months Ended

Mar. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

LICENSE AND COLLABORATION AGREEMENTS

3. LICENSE AND COLLABORATION AGREEMENTS

Roche Holding A.G.

For the three months ended March 31, 2021 and 2020, the Company recognized $22.0 million and $13.2 million of collaboration revenue, respectively, associated with the license, collaboration and option agreement (the “Roche Agreement”) with Roche Holding A.G. (“Roche”). As of March 31, 2021, the Company has total deferred revenue of $730.7 million associated with the Roche Agreement, of which $89.2 million is classified as current. The portion of deferred revenue related to the separate material rights for the options to acquire ex-U.S. rights to certain DMD-specific programs was $485.0 million as of March 31, 2021.

The costs associated with co-development activities performed under the Roche Agreement are included in operating expenses, with any reimbursement of costs by Roche reflected as a reduction of such expenses when the related expense is incurred. For the three months ended March 31, 2021 and 2020, costs reimbursable by Roche and reflected as a reduction to operating expenses were $13.4 million and $16.4 million, respectively. As of March 31, 2021, there was $15.1 million of collaboration receivable included in other current assets.

BioMarin Pharmaceutical, Inc.

The FDA approval of AMONDYS 45 (casimersen) in February 2021 resulted in a settlement charge to BioMarin Pharmaceutical, Inc. (“BioMarin”) under the terms of the previous settlement agreement with BioMarin. This amount, which was expensed as incurred, is separately presented in the statement of operations for the three months ended March 31, 2021.

Research and Option Agreements

The Company has research and option agreements with third parties in order to develop various technologies and biologics that may be used in the administration of the Company’s genetic therapeutics. The agreements generally provide for research services related to preclinical development programs, and options to license the technology for clinical development. Prior to the options under these agreements being executed, the Company may be required to make up to $14.0 million in research milestone payments. Under these agreements, there are $237.0 million in potential option payments to be made by the Company upon the determination to exercise the options. Additionally, if the options for each agreement are executed, the Company would incur additional contingent obligations and may be required to make development, regulatory, and sales milestone payments and tiered royalty payments based on the sales of the developed products upon commercialization. As of March 31, 2021, the Company has not exercised any options nor have any research milestone payments become probable of occurring.

Milestone Obligations

The Company has license and collaboration agreements in place for which it could be obligated to pay, in addition to the payment of up-front fees upon execution of the agreements, certain milestone payments as a product candidate proceeds from the submission of an investigational new drug application through approval for commercial sale and beyond. As of March 31, 2021, the Company may be obligated to make up to $3.9 billion in future development, regulatory, commercial and up-front royalty milestone payments associated with its license and collaboration agreements. These obligations exclude potential future option and milestone payments for options that have yet to be exercised within agreements entered into by the Company as of March 31, 2021, which are discussed above. For the three months ended March 31, 2021 and 2020, the Company recognized up-front, development milestone, settlement and other expenses of $14.0 million and $8.5 million, respectively, as research and development expense in the accompanying unaudited condensed consolidated statement of operations and comprehensive loss.

GAIN FROM SALE OF PRIORITY REVIEW VOUCHER

3 Months Ended

Mar. 31, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

GAIN FROM SALE OF PRIORITY REVIEW VOUCHER

4. GAIN FROM SALE OF PRIORITY REVIEW VOUCHER

In February 2021, the Company entered into an agreement to sell the rare pediatric disease Priority Review Voucher (“PRV”) it received from the FDA in connection with the approval of AMONDYS 45 for consideration of $102.0 million. The closing of the transaction is subject to the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and other customary conditions. The transaction closed on April 13, 2021 and the net proceeds will be recorded as a gain from sale of the PRV as it does not have a carrying value at the time of the sale during the quarter ended June 30, 2021.

In February 2020, the Company entered into an agreement to sell the rare pediatric disease PRV it received from the FDA in connection with the approval of VYONDYS 53. Following the early termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, in March 2020, the Company completed its sale of the PRV and received proceeds of $108.1 million, net of commission, which was recorded as a gain from sale of the PRV as it did not have a carrying value at the time of the sale.

FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

5. FAIR VALUE MEASUREMENTS

The Company has certain financial assets and liabilities that are recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements.

•

Level 1 — quoted prices for identical instruments in active markets;

•

Level 2 — quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets; and

•

Level 3 — valuations derived from valuation techniques in which one or more significant value drivers are unobservable.

The tables below present information about the Company’s financial assets and liabilities that are measured and carried at fair value and indicate the level within the fair value hierarchy of valuation techniques it utilizes to determine such fair value:

	Fair Value Measurement as of March 31, 2021
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	1,053,383	$	1,053,383	$	—	$	—
Government and government agency bonds		359,029		359,029		—		—
Strategic equity investments		40,640		3,740		—		36,900
Certificates of deposit		250		250		—		—
Total assets	$	1,453,302	$	1,416,402	$	—	$	36,900

Liabilities
Contingent consideration	$	50,800	$	—	$	—	$	50,800
Total liabilities	$	50,800	$	—	$	—	$	50,800

	Fair Value Measurement as of December 31, 2020
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	629,440	$	629,440	$	—	$	—
Government and government agency bonds		1,037,981		1,037,981		—		—
Strategic equity investments		38,799		3,699		—		35,100
Certificates of deposit		250		250		—		—
Total assets	$	1,706,470	$	1,671,370	$	—	$	35,100

Liabilities
Contingent consideration	$	50,800	$	—	$	—	$	50,800
Total liabilities	$	50,800	$	—	$	—	$	50,800

The Company’s assets with fair value categorized as Level 1 within the fair value hierarchy include money market funds, government and government agency bonds, the Company’s strategic investment in Lysogene S.A. and certificates of deposit. Certain of the government and government agency bonds are publicly traded fixed income securities and are presented as cash equivalents on the unaudited condensed consolidated balance sheets as of March 31, 2021.

The Company’s assets with fair value categorized as Level 3 within the fair value hierarchy consist of a strategic investment in Series A preferred stock of Lacerta Therapeutics, Inc. (“Lacerta”) and strategic investments in Series A and Series B preferred stock of two other private companies. For more information related to Lacerta, please read Note 3, License and Collaboration Agreements of the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. The fair value of the Lacerta investment was initially based on a cost approach corroborated by the Black-Scholes option pricing model. The most significant assumptions in the option pricing model include historical volatility of similar public companies, estimated term through Lacerta’s potential exit and a risk-free rate based on certain U.S. Treasury rates. The investment in the other two private companies are recorded at fair value at the time of purchase as measured by their respective investment cost. At the end of each reporting period, the fair value of investments in equity securities will be adjusted if the issuers were to issue similar or identical equity securities or when there is a triggering event for impairment. There were no changes in the fair value of the strategic investments during the three months ended March 31, 2021, other than the additional investment of $1.8 million in Series B preferred stock of a private company.

The Company’s contingent consideration liability with fair value categorized as Level 3 within the fair value hierarchy relate to the regulatory-related contingent payments to Myonexus Therapeutics, Inc. (“Myonexus”) selling shareholders as well as to two academic institutions under separate license agreements that meet the definition of a derivative. For more information related to Myonexus, please read Note 3, License and Collaboration Agreements of the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. The contingent consideration liability was estimated using an income approach based on the probability-weighted expected cash flows that incorporated industry-based probability adjusted assumptions relating to the achievement of the milestone and thus the likelihood of making the payments. This fair value measurement was based upon significant inputs not observable in the market and therefore represented a Level 3 measurement. Significant changes which increase or decrease the probabilities of achieving the milestone or shorten or lengthen the time required to achieve the milestone would result in a corresponding increase or decrease in the fair value of the liability. At the end of each reporting period, the fair value is adjusted to reflect the most current assumptions through earnings.

There were no transfers between levels 1, 2 and 3 during the three months ended March 31, 2021. For the three months ended March 31, 2021, there have been no changes to the fair value of the contingent consideration liability. As of March 31, 2021, the contingent consideration was recorded as a non-current liability on the Company’s unaudited condensed consolidated balance sheets.

The carrying amounts reported in the unaudited condensed consolidated balance sheets for cash and cash equivalents, accounts receivable and accounts payable approximated fair value because of the short-term maturity of these financial instruments.

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

3 Months Ended

Mar. 31, 2021

Cash And Cash Equivalents [Abstract]

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

6. CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES

The following table summarizes the Company’s financial assets with maturities of less than 90 days from the date of purchase included in cash equivalents in the unaudited condensed consolidated balance sheets for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Money market funds	$	1,053,383	$	629,440
Government and government agency bonds		103,032		602,058
Total	$	1,156,415	$	1,231,498

It is the Company’s policy to mitigate credit risk in its financial assets by maintaining a well-diversified portfolio that limits the amount of exposure as to maturity and investment type. The weighted average maturity of the Company’s available-for-sale securities as of March 31, 2021 and December 31, 2020 was approximately one and two months, respectively.

The following tables summarize the Company’s cash, cash equivalents and short-term investments as of the periods indicated:

	As of March 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(in thousands)
Cash and money market funds	$	1,378,804	$	—	$	—	$	1,378,804
Government and government agency bonds		359,013		16		—		359,029
Total cash, cash equivalents and investments	$	1,737,817	$	16	$	—	$	1,737,833
As reported:
Cash and cash equivalents	$	1,481,836	$	—	$	—	$	1,481,836
Short-term investments		255,981		16		—		255,997
Total cash, cash equivalents and investments	$	1,737,817	$	16	$	—	$	1,737,833

	As of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(in thousands)
Cash and money market funds	$	900,590	$	—	$	—	$	900,590
Government and government agency bonds		1,037,959		22		—		1,037,981
Total cash, cash equivalents and investments	$	1,938,549	$	22	$	—	$	1,938,571
As reported:
Cash and cash equivalents	$	1,502,639	$	9	$	—	$	1,502,648
Short-term investments		435,910		13		—		435,923
Total cash, cash equivalents and investments	$	1,938,549	$	22	$	—	$	1,938,571

PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES

3 Months Ended

Mar. 31, 2021

Receivables Net Current [Abstract]

PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES

7. PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES

The following table summarizes the Company’s product revenues, net by product for the periods indicated:

	For the Three Months Ended March 31,
	2021		2020
	(in thousands)
EXONDYS 51	$	107,185	$	98,183
VYONDYS 53		17,548		2,265
AMONDYS 45		193		—
Product revenues, net	$	124,926	$	100,448

The following table summarizes the components of the Company’s accounts receivable for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Product sales receivable, net of discounts and allowances	$	117,733	$	100,870
Government contract receivables		470		470
Total accounts receivable, net	$	118,203	$	101,340

The balance for government contract receivables for both periods presented is subject to government audit and will not be collected until the completion of the audit.

The following tables summarize an analysis of the change in reserves for discounts and allowances for each of the periods indicated:

	Chargebacks			Rebates			Prompt Pay			Other Accruals			Total
	(in thousands)
Balance, as of December 31, 2020	$	2,281		$	41,771		$	1,949		$	4,969		$	50,970
Provision		2,085			14,907			1,844			3,191			22,027
Payments/credits		(3,969	)		(9,108	)		(1,432	)		(2,619	)		(17,128	)
Balance, as of March 31, 2021	$	397		$	47,570		$	2,361		$	5,541		$	55,869

	Chargebacks			Rebates			Prompt Pay			Other Accruals			Total
	(in thousands)
Balance, as of December 31, 2019	$	588		$	44,738		$	1,506		$	4,671		$	51,503
Provision		2,435			12,083			1,373			2,103			17,994
Payments/credits		(2,336	)		(10,979	)		(1,291	)		(4,023	)		(18,629	)
Balance, as of March 31, 2020	$	687		$	45,842		$	1,588		$	2,751		$	50,868

The following table summarizes the total reserves included in the Company’s unaudited condensed consolidated balance sheets for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Reduction to accounts receivable	$	7,421	$	8,352
Component of accrued expenses		48,448		42,618
Total reserves	$	55,869	$	50,970

INVENTORY

3 Months Ended

Mar. 31, 2021

Inventory Disclosure [Abstract]

INVENTORY

8. INVENTORY

The following table summarizes the components of the Company’s inventory for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Raw materials	$	62,244	$	71,717
Work in progress		149,811		139,704
Finished goods		28,278		20,540
Total inventory	$	240,333	$	231,961

OTHER ASSETS

3 Months Ended

Mar. 31, 2021

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

OTHER ASSETS

9. OTHER ASSETS

The following table summarizes the Company’s other current assets for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Manufacturing-related deposits and prepaids	$	114,659	$	134,430
Prepaid clinical and pre-clinical expenses		17,539		16,224
Collaboration receivable		15,105		34,184
Prepaid maintenance services		8,063		6,411
Prepaid research expenses		4,620		5,854
Prepaid income tax		3,930		4,939
Leasehold improvement receivable		3,059		3,059
Prepaid insurance		2,637		4,158
Other		5,369		4,065
Total other current assets	$	174,981	$	213,324

The following table summarizes the Company’s other non-current assets for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Manufacturing-related deposits and prepaids	$	156,413	$	148,525
Strategic investments		40,640		38,799
Restricted cash and investments		9,315		9,315
Prepaid clinical expenses		2,124		3,395
Other		3,092		3,669
Total other non-current assets	$	211,584	$	203,703

ACCRUED EXPENSES

3 Months Ended

Mar. 31, 2021

Payables And Accruals [Abstract]

ACCRUED EXPENSES

10. ACCRUED EXPENSES

The following table summarizes the Company’s accrued expenses for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Product revenue related reserves	$	48,448	$	42,618
Accrued contract manufacturing costs		34,556		36,543
Accrued clinical and pre-clinical costs		24,580		22,169
Accrued employee compensation costs		23,520		50,803
Accrued professional fees		10,990		10,221
Accrued milestone expense		9,377		9,380
Accrued collaboration cost sharing		8,962		3,516
Accrued royalties		8,019		7,793
Accrued property and equipment		5,056		4,993
Accrued interest expense		3,182		1,045
Other		3,946		4,472
Total accrued expenses	$	180,636	$	193,553

INDEBTEDNESS

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

INDEBTEDNESS

11. INDEBTEDNESS

2024 Convertible Notes

On November 14, 2017, the Company issued $570.0 million senior notes due on November 15, 2024 (the “2024 Notes”). The 2024 Notes were issued at face value and bear interest at the rate of 1.50% per annum, payable semi-annually in cash on each May 15 and November 15, commencing on May 15, 2018. The 2024 Notes contain customary covenants and events of default, occurrence of which permits the certain holders to accelerate all outstanding obligations, including principal and interest. The Company incurred $10.6 million of offering costs, which represents the total debt discount on the 2024 Notes at issuance. The debt discount is amortized under the effective interest method and recorded as additional interest expense over the life of the 2024 Notes.

Upon conversion, the Company may pay cash, shares of its common stock or a combination of cash and stock, as determined by the Company in its discretion. The 2024 Notes may be convertible into 7,763,552 shares of the Company’s common stock under certain circumstances prior to maturity at a conversion rate of 13.621 shares per $1,000 principal amount of the 2024 Notes, which represents a conversion price of $73.42 per share, subject to adjustment under certain conditions. For more information related to the 2024 Notes, please read Note 13, Indebtedness of the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

Upon adoption of ASU 2020-06, the 2024 Notes are accounted for as a single liability measured at its amortized cost. The cumulative effect of the accounting change as of January 1, 2021 increased the carrying amount of the convertible notes by $96.8 million, reduced the accumulated deficit by $60.2 million and reduced additional paid-in capital by $157.0 million. Interest expense of the 2024 convertible notes will be lower as a result of adoption of this guidance. The effective interest rate on the liability component of the 2024 Notes for the three months ended March 31, 2021 was 1.9%. For the three months ended March 31, 2021 and 2020, the interest expense related to the 2024 Notes was $2.7 million and $7.7 million, respectively. The fair value of the Company’s 2024 Notes as of March 31, 2021 was $735.0 million, based on open market trades and is classified as level 1 in the fair value hierarchy.

December 2019 Term Loan

There have been no material changes to the December 2019 Term Loan in the three months ended March 31, 2021. For more information related to the term loan, please read Note 13, Indebtedness of the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

The following table summarizes the Company’s debt facilities for the periods indicated:

	As of March 31, 2021			As of December 31, 2020
	(in thousands)
Principal amount of the 2024 Notes	$	569,993		$	569,993
Unamortized discount - equity component		—			(98,721	)
Unamortized discount - debt issuance costs		(7,913	)		(6,510	)
Net carrying value of 2024 Notes		562,080			464,762
Principal amount of the 2019 Term Loan		550,000			550,000
Unamortized discounts		(20,970	)		(22,269	)
Net carrying value of 2019 Term Loan		529,030			527,731
Total carrying value of debt facilities	$	1,091,110		$	992,493

The following table summarizes the total gross payments due under the Company’s debt arrangements:

	As of March 31, 2021 (in thousands)
2021 (April-December)	$	—
2022		—
2023		250,000
2024		869,993
2025		—
Thereafter		—
Total payments	$	1,119,993

STOCK-BASED COMPENSATION

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

STOCK-BASED COMPENSATION

12. STOCK-BASED COMPENSATION

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended March 31,
	2021				2020
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options		1,359,637	$	49.35		1,085,330	$	56.80
Restricted stock units		689,367	$	87.14		498,910	$	114.28

Stock-based Compensation Expense

For the three months ended March 31, 2021 and 2020, total stock-based compensation expense was $28.5 million and $24.0 million, respectively. The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended March 31,
	2021		2020
Research and development	$	11,126	$	9,249
Selling, general and administrative		17,382		14,775
Total stock-based compensation expense	$	28,508	$	24,024

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended March 31,
	2021		2020
Stock options	$	17,019	$	15,355
Restricted stock awards/units		9,931		6,745
Employee stock purchase plan		1,558		1,924
Total stock-based compensation expense	$	28,508	$	24,024

OTHER (LOSS) INCOME

3 Months Ended

Mar. 31, 2021

Other Income And Expenses [Abstract]

OTHER (LOSS) INCOME

13. OTHER (LOSS) INCOME

The following table summarizes other (loss) income for the periods indicated:

	For the Three Months Ended March 31,
	2021			2020

Interest expense	$	(15,651	)	$	(13,615	)
Interest income		59			2,139
Amortization of investment discount		136			2,964
Gain from sale of Priority Review Voucher		—			108,069
Other (expense) income, net		(72	)		1,092
Total other (loss) income	$	(15,528	)	$	100,649

NET LOSS PER SHARE

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

NET LOSS PER SHARE

14. NET LOSS PER SHARE

Basic net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock outstanding. Diluted net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding. For the three months ended March 31, 2021 and 2020, there were no differences between basic and diluted net loss per share since the effect of common stock equivalents would be anti-dilutive due to the net loss position and, therefore, would be excluded from the diluted net loss per share calculation.

	For the Three Months Ended March 31,
	2021			2020
Net loss	$	(167,250	)	$	(17,492	)
Weighted-average common shares outstanding - basic		79,454			76,432
Effect of dilutive securities*		—
Weighted-average common shares outstanding - diluted		79,454			76,432
Net loss per share - basic and diluted	$	(2.10	)	$	(0.23	)

For the three months ended March 31, 2021 and 2020, stock options, RSAs, RSUs, and ESPP to purchase 10.3 million and 10.5 million shares of the Company’s common stock, respectively, were excluded from the diluted net loss per share calculation as their effect would have been anti-dilutive. The Company accounts for the effect of the 2024 Notes on diluted net earnings per share using the if-converted method as this obligation may be settled in cash or shares at the Company’s option. The effect of potential share settlement is included in the diluted EPS calculation if the effect is more dilutive. During the three months ended March 31, 2021, the inclusion of the potential share settlement of the 2024 was anti-dilutive.

COMMITMENTS AND CONTINGENCIES

3 Months Ended

Mar. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

15. COMMITMENTS AND CONTINGENCIES

Manufacturing Obligations

The following table summarizes the aggregate non-cancelable contractual obligations arising from the Company’s manufacturing obligations:

	As of March 31, 2021 (in thousands)
2021 (April - December)	$	523,673
2022		261,697
2023		224,980
2024		120,585
2025		114,531
Thereafter		207,325
Total manufacturing commitments*	$	1,452,791

Total manufacturing commitments include both the Catalent and Thermo manufacturing and supply agreements. Related to the embedded leases at Catalent and Thermo , the Company has an ROU asset and a lease liability recorded on the unaudited condensed consolidated balance sheets as of March 31, 2021. For more information, please read Note 19, Leases of the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

Additionally, should the Company obtain regulatory approval for any drug product candidate produced as a part of the Company’s manufacturing obligations above, additional minimum batch requirements with the respective manufacturing parties would be required.

The Company has leases embedded in two of its manufacturing and supply agreements as the Company determined that it controls the use of clean room suites and the related equipment therein. During the three months ended March 31, 2021, the Company modified the terms of its manufacturing and supply agreement with Catalent, Inc. The modification decreased the Company’s right of use of certain dedicated clean room suites and reduced the fixed and in-substance fixed payments due over the remaining term of the agreement. The modification was accounted for as a partial lease termination, resulting in: (i) the derecognition of right of use assets of $22.8 million, (ii) the derecognition of lease liabilities of $20.0 million, and (iii) the recognition of a loss of $2.8 million, which is included in research and development expense.

Litigation

In the normal course of business, the Company may from time to time be named as a party to various legal claims, actions and complaints, including matters involving securities, employment, intellectual property, effects from the use of therapeutics utilizing its technology, or others.

On September 15, 2020, REGENXBIO INC. (“RegenX”) and the Trustees of the University of Pennsylvania filed a lawsuit against the Company and Sarepta Therapeutics Three, LLC (together, “Sarepta”), in the U.S. District Court for the District of Delaware. The plaintiffs assert patent infringement of U.S. Patent No. 10,526,617 (“the ‘617 Patent”) under 35 U.S.C.§§ 271(a)-(c) based on Sarepta’s alleged direct or indirect manufacture and use of cultured host cell technology to make adeno-associated virus (“AAV”) gene therapy products, including SRP-9001. Specifically, the Complaint essentially includes the allegation that Sarepta’s use, and the use by its contract manufacturers on its behalf, of a host cell containing a recombinant acid molecule that encodes a capsid protein having at least 95% amino acid identity to AAVrh10 infringes upon the ‘617 Patent asserted by RegenX. Plaintiffs seek injunctive relief, a judgment of infringement, an unspecified amount of damages that is no less than a reasonable royalty, a judgment of willful infringement, attorneys’ fees and costs, and such other relief as the court deems just and proper. On September 30, 2020, the Court endorsed a stipulation filed by the parties extending Sarepta’s time to respond to the complaint to and including November 6,

2020. On November 4, 2020, Sarepta moved to dismiss the case pursuant to Federal Rule of Civil Procedure 12(b)(6) based on the Safe Harbor provision of non-infringement contained in 35 U.S.C. § 271(e)(1). On December 16, 2020, Sarepta and RegenX both filed requests for oral argument. The Court has not scheduled a date for the hearing. We are unable to provide an estimate of possible loss or range of possible loss.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), reflect the accounts of Sarepta and its wholly-owned subsidiaries. All intercompany transactions between and among its consolidated subsidiaries have been eliminated. Management has determined that the Company operates in one segment: discovering, developing, manufacturing and delivering therapies to patients with rare diseases. In the opinion of the Company’s management, all adjustments of a normal recurring nature necessary for a fair presentation have been reflected. Certain financial information that is normally included in annual financial statements prepared in accordance with the U.S. GAAP, but that is not required for interim reporting purposes, has been omitted. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2020 which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the U.S. Securities and Exchange Commission on March 1, 2021. The results for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the full year.
Estimates and Uncertainties	Estimates and Uncertainties The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, equity, revenue, expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of accounts receivable from customers, cash held at financial institutions and cash equivalents and investments. As of March 31, 2021, the majority of the Company’s accounts receivable arose from product sales in the U.S. and all customers have standard payment terms that generally require payment within 60 to 91 days. Outside of the U.S., the majority of the Company’s customers have payment terms ranging between 45 and 150 days. Three individual customers accounted for 49%, 40 % and 7% of net product revenues for the three months ended March 31, 2021 and 44%, 40 % and 12% of net product revenues for the three months ended March 31, 2020. Three individual customers accounted for 49%, 40% and 7% of accounts receivable from product sales as of March 31, 2021 and 45%, 41% and 9% of accounts receivable from product sales as of December 31, 2020. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in its customers’ credit profile. As of March 31, 2021, the Company believes that such customers are of high credit quality. As of March 31, 2021, the Company’s cash was concentrated at three financial institutions in the U.S., which potentially exposes the Company to credit risks. However, the Company does not believe that there is significant risk of non-performance by the financial institutions. Significant Accounting Policies For details about the Company’s accounting policies, please read Note 2, Summary of Significant Accounting Policies and Recent Accounting Pronouncements of the Annual Report on Form 10-K for the year ended December 31, 2020. There have not been any material changes to the Company’s accounting policies through March 31, 2021, other than those noted below relating to the adoption of ASU 2020-06, “Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity.”
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently adopted In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU 2020-06, “Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity.” This ASU simplifies the complexity associated with applying U.S. GAAP for certain financial instruments with characteristics of liabilities and equity. More specifically, the amendments focus on the guidance for convertible instruments and derivative scope exceptions for contracts in an entity’s own equity. Under ASU 2020-06, the embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives under Topic 815, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument, such as the Company’s senior notes due on November 15, 2024 (the “2024 Notes”), will be accounted for as a single liability measured at its amortized cost, as long as no other features require bifurcation and recognition as derivatives. The new guidance also requires the if-converted method to be applied for all convertible instruments and requires additional disclosures. This guidance is required to be adopted by January 1, 2022, and early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020. The Company has elected to early adopt this guidance on January 1, 2021, using the modified retrospective method. Under this transition method, the cumulative effect of the accounting change removed the impact of recognizing the equity component of the Company’s convertible notes (at issuance and the subsequent accounting impact of additional interest expense from debt discount amortization). The cumulative effect of the accounting change as of January 1, 2021 increased the carrying amount of the convertible notes by $96.8 million, reduced accumulated deficit by $60.2 million and reduced additional paid-in capital by $157.0 million. Interest expense of the 2024 Notes will be lower as a result of adoption of this guidance. The if-converted method for such instruments will be used to compute diluted net earnings per share if and when profitability is achieved. As a result of the adoption of this guidance, interest expense and net loss was reduced by $5.4 million for the three months ended March 31, 2021, which was $0.07 per share. In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”, which is intended to simplify the accounting for income taxes. This ASU removes certain exceptions to the general principles in Topic 740 and clarifies and amends existing guidance to improve consistent application. The new guidance was effective beginning January 1, 2021. The adoption of this guidance did not have a material effect on the Company’s consolidated financial statements.

FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured and Carried at Fair Value

	Fair Value Measurement as of March 31, 2021
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	1,053,383	$	1,053,383	$	—	$	—
Government and government agency bonds		359,029		359,029		—		—
Strategic equity investments		40,640		3,740		—		36,900
Certificates of deposit		250		250		—		—
Total assets	$	1,453,302	$	1,416,402	$	—	$	36,900

Liabilities
Contingent consideration	$	50,800	$	—	$	—	$	50,800
Total liabilities	$	50,800	$	—	$	—	$	50,800

	Fair Value Measurement as of December 31, 2020
	Total		Level 1		Level 2		Level 3
	(in thousands)
Assets
Money market funds	$	629,440	$	629,440	$	—	$	—
Government and government agency bonds		1,037,981		1,037,981		—		—
Strategic equity investments		38,799		3,699		—		35,100
Certificates of deposit		250		250		—		—
Total assets	$	1,706,470	$	1,671,370	$	—	$	35,100

Liabilities
Contingent consideration	$	50,800	$	—	$	—	$	50,800
Total liabilities	$	50,800	$	—	$	—	$	50,800

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Tables)

3 Months Ended

Mar. 31, 2021

Cash And Cash Equivalents [Abstract]

Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Money market funds	$	1,053,383	$	629,440
Government and government agency bonds		103,032		602,058
Total	$	1,156,415	$	1,231,498

Summary of Company Cash, Cash Equivalents and Short-Term Investments

The following tables summarize the Company’s cash, cash equivalents and short-term investments as of the periods indicated:

	As of March 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(in thousands)
Cash and money market funds	$	1,378,804	$	—	$	—	$	1,378,804
Government and government agency bonds		359,013		16		—		359,029
Total cash, cash equivalents and investments	$	1,737,817	$	16	$	—	$	1,737,833
As reported:
Cash and cash equivalents	$	1,481,836	$	—	$	—	$	1,481,836
Short-term investments		255,981		16		—		255,997
Total cash, cash equivalents and investments	$	1,737,817	$	16	$	—	$	1,737,833

	As of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(in thousands)
Cash and money market funds	$	900,590	$	—	$	—	$	900,590
Government and government agency bonds		1,037,959		22		—		1,037,981
Total cash, cash equivalents and investments	$	1,938,549	$	22	$	—	$	1,938,571
As reported:
Cash and cash equivalents	$	1,502,639	$	9	$	—	$	1,502,648
Short-term investments		435,910		13		—		435,923
Total cash, cash equivalents and investments	$	1,938,549	$	22	$	—	$	1,938,571

PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE AND RESERVES FOR PRODUCT SALES (Tables)

3 Months Ended

Mar. 31, 2021

Receivables Net Current [Abstract]

Summary of Product Revenues

The following table summarizes the Company’s product revenues, net by product for the periods indicated:

	For the Three Months Ended March 31,
	2021		2020
	(in thousands)
EXONDYS 51	$	107,185	$	98,183
VYONDYS 53		17,548		2,265
AMONDYS 45		193		—
Product revenues, net	$	124,926	$	100,448

Summary of Components of Accounts Receivable

The following table summarizes the components of the Company’s accounts receivable for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Product sales receivable, net of discounts and allowances	$	117,733	$	100,870
Government contract receivables		470		470
Total accounts receivable, net	$	118,203	$	101,340

Summary of Change in Reserves for Discounts and Allowances

The following tables summarize an analysis of the change in reserves for discounts and allowances for each of the periods indicated:

	Chargebacks			Rebates			Prompt Pay			Other Accruals			Total
	(in thousands)
Balance, as of December 31, 2020	$	2,281		$	41,771		$	1,949		$	4,969		$	50,970
Provision		2,085			14,907			1,844			3,191			22,027
Payments/credits		(3,969	)		(9,108	)		(1,432	)		(2,619	)		(17,128	)
Balance, as of March 31, 2021	$	397		$	47,570		$	2,361		$	5,541		$	55,869

	Chargebacks			Rebates			Prompt Pay			Other Accruals			Total
	(in thousands)
Balance, as of December 31, 2019	$	588		$	44,738		$	1,506		$	4,671		$	51,503
Provision		2,435			12,083			1,373			2,103			17,994
Payments/credits		(2,336	)		(10,979	)		(1,291	)		(4,023	)		(18,629	)
Balance, as of March 31, 2020	$	687		$	45,842		$	1,588		$	2,751		$	50,868

Summary of Total Reserves Included in Consolidated Balance Sheets

The following table summarizes the total reserves included in the Company’s unaudited condensed consolidated balance sheets for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Reduction to accounts receivable	$	7,421	$	8,352
Component of accrued expenses		48,448		42,618
Total reserves	$	55,869	$	50,970

INVENTORY (Tables)

3 Months Ended

Mar. 31, 2021

Inventory Disclosure [Abstract]

Summary of Components of Inventory

The following table summarizes the components of the Company’s inventory for the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Raw materials	$	62,244	$	71,717
Work in progress		149,811		139,704
Finished goods		28,278		20,540
Total inventory	$	240,333	$	231,961

OTHER ASSETS (Tables)

3 Months Ended

Mar. 31, 2021

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Summary of Other Current Assets

The following table summarizes the Company’s other current assets for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Manufacturing-related deposits and prepaids	$	114,659	$	134,430
Prepaid clinical and pre-clinical expenses		17,539		16,224
Collaboration receivable		15,105		34,184
Prepaid maintenance services		8,063		6,411
Prepaid research expenses		4,620		5,854
Prepaid income tax		3,930		4,939
Leasehold improvement receivable		3,059		3,059
Prepaid insurance		2,637		4,158
Other		5,369		4,065
Total other current assets	$	174,981	$	213,324

Summary of Other Non-current Assets

The following table summarizes the Company’s other non-current assets for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Manufacturing-related deposits and prepaids	$	156,413	$	148,525
Strategic investments		40,640		38,799
Restricted cash and investments		9,315		9,315
Prepaid clinical expenses		2,124		3,395
Other		3,092		3,669
Total other non-current assets	$	211,584	$	203,703

ACCRUED EXPENSES (Tables)

3 Months Ended

Mar. 31, 2021

Payables And Accruals [Abstract]

Summary of Accrued Expenses

The following table summarizes the Company’s accrued expenses for each of the periods indicated:

	As of March 31, 2021		As of December 31, 2020
	(in thousands)
Product revenue related reserves	$	48,448	$	42,618
Accrued contract manufacturing costs		34,556		36,543
Accrued clinical and pre-clinical costs		24,580		22,169
Accrued employee compensation costs		23,520		50,803
Accrued professional fees		10,990		10,221
Accrued milestone expense		9,377		9,380
Accrued collaboration cost sharing		8,962		3,516
Accrued royalties		8,019		7,793
Accrued property and equipment		5,056		4,993
Accrued interest expense		3,182		1,045
Other		3,946		4,472
Total accrued expenses	$	180,636	$	193,553

INDEBTEDNESS (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Summary of Debt Facilities

The following table summarizes the Company’s debt facilities for the periods indicated:

	As of March 31, 2021			As of December 31, 2020
	(in thousands)
Principal amount of the 2024 Notes	$	569,993		$	569,993
Unamortized discount - equity component		—			(98,721	)
Unamortized discount - debt issuance costs		(7,913	)		(6,510	)
Net carrying value of 2024 Notes		562,080			464,762
Principal amount of the 2019 Term Loan		550,000			550,000
Unamortized discounts		(20,970	)		(22,269	)
Net carrying value of 2019 Term Loan		529,030			527,731
Total carrying value of debt facilities	$	1,091,110		$	992,493

Summarizes Total Gross Payments Due under Company's Debt Arrangements

The following table summarizes the total gross payments due under the Company’s debt arrangements:

	As of March 31, 2021 (in thousands)
2021 (April-December)	$	—
2022		—
2023		250,000
2024		869,993
2025		—
Thereafter		—
Total payments	$	1,119,993

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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+ Details

STOCK-BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Awards Granted

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended March 31,
	2021				2020
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options		1,359,637	$	49.35		1,085,330	$	56.80
Restricted stock units		689,367	$	87.14		498,910	$	114.28

Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statements of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended March 31,
	2021		2020
Research and development	$	11,126	$	9,249
Selling, general and administrative		17,382		14,775
Total stock-based compensation expense	$	28,508	$	24,024

Summary of Stock-Based Compensation Expense by Grant Type Included within Consolidated Statements of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended March 31,
	2021		2020
Stock options	$	17,019	$	15,355
Restricted stock awards/units		9,931		6,745
Employee stock purchase plan		1,558		1,924
Total stock-based compensation expense	$	28,508	$	24,024

OTHER (LOSS) INCOME (Tables)

3 Months Ended

Mar. 31, 2021

Other Income And Expenses [Abstract]

Summary of Other (Loss) Income

The following table summarizes other (loss) income for the periods indicated:

	For the Three Months Ended March 31,
	2021			2020

Interest expense	$	(15,651	)	$	(13,615	)
Interest income		59			2,139
Amortization of investment discount		136			2,964
Gain from sale of Priority Review Voucher		—			108,069
Other (expense) income, net		(72	)		1,092
Total other (loss) income	$	(15,528	)	$	100,649

NET LOSS PER SHARE (Tables)

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Basic and Diluted Net Loss Per Share

For the three months ended March 31, 2021 and 2020, there were no differences between basic and diluted net loss per share since the effect of common stock equivalents would be anti-dilutive due to the net loss position and, therefore, would be excluded from the diluted net loss per share calculation.

	For the Three Months Ended March 31,
	2021			2020
Net loss	$	(167,250	)	$	(17,492	)
Weighted-average common shares outstanding - basic		79,454			76,432
Effect of dilutive securities*		—
Weighted-average common shares outstanding - diluted		79,454			76,432
Net loss per share - basic and diluted	$	(2.10	)	$	(0.23	)

COMMITMENTS AND CONTINGENCIES (Tables)

3 Months Ended

Mar. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Summary of Aggregate Non-Cancelable Contractual Obligations Arising from Manufacturing Obligations

The following table summarizes the aggregate non-cancelable contractual obligations arising from the Company’s manufacturing obligations:

	As of March 31, 2021 (in thousands)
2021 (April - December)	$	523,673
2022		261,697
2023		224,980
2024		120,585
2025		114,531
Thereafter		207,325
Total manufacturing commitments*	$	1,452,791

Organization and Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Cash, cash equivalents and investments	$ 1,747,100
Cash and cash equivalents	1,481,836	$ 1,502,648	$ 1,764,212
Short-term investments	255,997	435,923
Restricted cash and investments	$ 9,315	$ 9,315

Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended	12 Months Ended
	Jan. 02, 2021 USD ($) $ / shares	Mar. 31, 2021 USD ($) Segment	Mar. 31, 2020 USD ($)	Sep. 30, 2020	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment		1
Net loss		$ (167,250)	$ (17,492)
ASU 2020-06
Summary Of Significant Accounting Policies [Line Items]
Increase in convertible notes	$ 96,800
Decrease in accumulated deficit	60,200
Decrease in additional paid-in-capital	157,000
Interest expense reduced	5,400
Net loss	$ 5,400
Increase in diluted earnings per share (in dollar per share) \| $ / shares	$ 0.07
Product Revenues [Member] \| Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		49.00%	44.00%
Product Revenues [Member] \| Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		40.00%	40.00%
Product Revenues [Member] \| Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		7.00%	12.00%
Accounts Receivable [Member] \| Customer One [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		49.00%			45.00%
Accounts Receivable [Member] \| Customer Two [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		40.00%			41.00%
Accounts Receivable [Member] \| Customer Three [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		7.00%			9.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term				60 days
Minimum [Member] \| Outside of U.S. [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term				45 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term				91 days
Maximum [Member] \| Outside of U.S. [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable payment term				150 days

License and Collaboration Agreements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue	$ 124,926	$ 100,448
Collaborative Arrangement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for option exercise	$ 237,000
Stock options exercised or expired	0
Development Milestone and Upfront Fee Recognized as Research and Development Expense	$ 14,000	8,500
Collaborative Arrangement \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent research milestone payments	14,000
Development Milestone and Settlement Upfront Fee Recognized as Research and Development Expense	3,900,000
Collaborative Arrangement \| Roche
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue	22,000	13,200
Deferred Revenue	730,700
Deferred Revenue, Current	89,200
Deferred Revenue Separate Material Options Right	485,000
Research and development expense	13,400	$ 16,400
Collaboration Receivable	$ 15,100

Gain from Sale of Priority Review Voucher - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
F D A
Gain From Sale Of Intangible Asset [Line Items]
Proceeds from sale of rare pediatric disease priority review voucher, Net of commission	$ 102.0	$ 108.1

Assets and Liabilities Measured and Carried at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 1,453,302	$ 1,706,470
Contingent consideration	50,800	50,800
Total liabilities	50,800	50,800
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,053,383	629,440
Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	359,029	1,037,981
Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	40,640	38,799
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	250	250
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,416,402	1,671,370
Level 1 [Member] \| Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,053,383	629,440
Level 1 [Member] \| Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	359,029	1,037,981
Level 1 [Member] \| Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	3,740	3,699
Level 1 [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	250	250
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	36,900	35,100
Contingent consideration	50,800	50,800
Total liabilities	50,800	50,800
Level 3 [Member] \| Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 36,900	$ 35,100

Fair Value Measurements - Additional Information (Detail) $ in Millions	Mar. 31, 2021 USD ($)
Lacerta Therapeutics Inc [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional investment	$ 1.8

Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 1,156,415	$ 1,231,498
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	1,053,383	629,440
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 103,032	$ 602,058

Cash, Cash Equivalents and Marketable Securities - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
Weighted average maturity period of available-for-sale securities	1 month	2 months

Summary of Company Cash, Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, Amortized cost	$ 1,481,836	$ 1,502,639
Cash and cash equivalents, Gross unrealized gains		9
Cash and cash equivalents	1,481,836	1,502,648	$ 1,764,212
Cash, cash equivalents and investments, Amortized cost	1,737,817	1,938,549
Cash, cash equivalents and investments, Gross unrealized gains	16	22
Cash, cash equivalents and investments, Fair value	1,737,833	1,938,571
Available for sale debt securities current, Amortized cost	255,981	435,910
Available for sale debt securities current, Gross unrealized gains	16	13
Available for sale debt securities current, Fair value	255,997	435,923
Cash and Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, Amortized cost	1,378,804	900,590
Cash and cash equivalents	1,378,804	900,590
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Amortized cost	359,013	1,037,959
Available for sale debt securities, Gross unrealized gains	16	22
Available for sale debt securities, Fair value	$ 359,029	$ 1,037,981

Summary of Product Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Products, net	$ 124,926	$ 100,448
EXONDYS 51 [Member]
Disaggregation Of Revenue [Line Items]
Products, net	107,185	98,183
VYONDYS 53 [Member]
Disaggregation Of Revenue [Line Items]
Products, net	17,548	$ 2,265
AMONDYS 45 [Member]
Disaggregation Of Revenue [Line Items]
Products, net	$ 193

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Summary of Components of Accounts Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Receivables Net Current [Abstract]
Product sales receivable, net of discounts and allowances	$ 117,733	$ 100,870
Government contract receivables	470	470
Total accounts receivable, net	$ 118,203	$ 101,340

Summary of Change in Reserves for Discounts and Allowances (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	$ 50,970	$ 51,503
Provision	22,027	17,994
Payments/credits	(17,128)	(18,629)
Ending balance	55,869	50,868
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	2,281	588
Provision	2,085	2,435
Payments/credits	(3,969)	(2,336)
Ending balance	397	687
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	41,771	44,738
Provision	14,907	12,083
Payments/credits	(9,108)	(10,979)
Ending balance	47,570	45,842
Prompt Pay [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	1,949	1,506
Provision	1,844	1,373
Payments/credits	(1,432)	(1,291)
Ending balance	2,361	1,588
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	4,969	4,671
Provision	3,191	2,103
Payments/credits	(2,619)	(4,023)
Ending balance	$ 5,541	$ 2,751

Summary of Total Reserves Included in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Receivables Net Current [Abstract]
Reduction to accounts receivable	$ 7,421	$ 8,352
Component of accrued expenses	48,448	42,618
Total reserves	$ 55,869	$ 50,970	$ 50,868	$ 51,503

Inventory - Summary of Components of Inventory (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 62,244	$ 71,717
Work in progress	149,811	139,704
Finished goods	28,278	20,540
Total inventory	$ 240,333	$ 231,961

Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 114,659	$ 134,430
Prepaid clinical and pre-clinical expenses	17,539	16,224
Collaboration receivable	15,105	34,184
Prepaid maintenance services	8,063	6,411
Prepaid research expenses	4,620	5,854
Prepaid income tax	3,930	4,939
Leasehold improvement receivable	3,059	3,059
Prepaid insurance	2,637	4,158
Other	5,369	4,065
Total other current assets	$ 174,981	$ 213,324

Summary of Other Non-current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Noncurrent [Abstract]
Manufacturing-related deposits and prepaids	$ 156,413	$ 148,525
Strategic investments	40,640	38,799
Restricted cash and investments	9,315	9,315
Prepaid clinical expenses	2,124	3,395
Other	3,092	3,669
Total other non-current assets	$ 211,584	$ 203,703

Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Product revenue related reserves	$ 48,448	$ 42,618
Accrued contract manufacturing costs	34,556	36,543
Accrued clinical and pre-clinical costs	24,580	22,169
Accrued employee compensation costs	23,520	50,803
Accrued professional fees	10,990	10,221
Accrued milestone expense	9,377	9,380
Accrued collaboration cost sharing	8,962	3,516
Accrued royalties	8,019	7,793
Accrued property and equipment	5,056	4,993
Accrued interest expense	3,182	1,045
Other	3,946	4,472
Total accrued expenses	$ 180,636	$ 193,553

Indebtedness - Additional Information (Detail)			3 Months Ended
Indebtedness - Additional Information (Detail)	Jan. 02, 2021 USD ($)	Nov. 14, 2017 USD ($) shares $ / shares	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount			$ 1,119,993,000
ASU 2020-06
Debt Instrument [Line Items]
Increase in convertible notes	$ 96,800,000
Decrease in accumulated deficit	60,200,000
Decrease in additional paid-in-capital	157,000,000.0
Interest expense reduced	5,400,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 570,000,000.0	$ 569,993,000		$ 569,993,000
Debt instrument, maturity date		Nov. 15, 2024
Debt instrument, interest rate per annum		1.50%
Debt instrument, payment frequency			The 2024 Notes contain customary covenants and events of default, occurrence of which permits the certain holders to accelerate all outstanding obligations, including principal and interest.
Debt issuance costs		$ 10,600,000
Debt instrument, conversion rate		0.013621
Debt instrument, conversion price \| $ / shares		$ 73.42
2024 Convertible Notes [Member] \| ASU 2020-06
Debt Instrument [Line Items]
Increase in convertible notes	96,800,000
Decrease in accumulated deficit	60,200,000
Decrease in additional paid-in-capital	$ 157,000,000.0
Effective interest rate percentage			1.90%
Interest expense reduced			$ 2,700,000	$ 7,700,000
Debt Instrument Fair Value			$ 735,000,000.0
2024 Convertible Notes [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, convertible into shares \| shares		7,763,552

Indebtedness - Summary of Debt Facilities (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Nov. 14, 2017
Debt Instrument [Line Items]
Principal amount	$ 1,119,993,000
Total carrying value of debt facilities	1,091,110,000	$ 992,493,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount	569,993,000	569,993,000	$ 570,000,000.0
Unamortized discount		(98,721,000)
Unamortized discount - debt issuance costs	(7,913,000)	(6,510,000)
Net carrying value	562,080,000	464,762,000
2019 Term Loan [Member]
Debt Instrument [Line Items]
Principal amount	550,000,000	550,000,000
Unamortized discount	(20,970,000)	(22,269,000)
Net carrying value	$ 529,030,000	$ 527,731,000

Indebtedness - Summarizes Total Gross Payments Due under Company's Debt Arrangements (Detail) $ in Thousands	Mar. 31, 2021 USD ($)
Debt Disclosure [Abstract]
2023	$ 250,000
2024	869,993
Total payments	$ 1,119,993

Summary of Stock Awards Granted (Detail) - $ / shares	3 Months Ended
Summary of Stock Awards Granted (Detail) - $ / shares	Mar. 31, 2021	Mar. 31, 2020
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	1,359,637	1,085,330
Weighted Average Grant Date Fair Value, Stock options	$ 49.35	$ 56.80
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Restricted stock units and awards	689,367	498,910
Weighted Average Grant Date Fair Value, Restricted stock units and awards	$ 87.14	$ 114.28

Stock Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based compensation expense	$ 28,508	$ 24,024

Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 28,508	$ 24,024
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	11,126	9,249
Selling, General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 17,382	$ 14,775

Summary of Stock-Based Compensation Expense by Grant Type Included within Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 28,508	$ 24,024
Stock Options [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	17,019	15,355
Restricted Stock Awards/Units (RSAs/RSUs) [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	9,931	6,745
Employee Stock Purchase Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,558	$ 1,924

Summary of Other (Loss) Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Nonoperating Income Expense [Abstract]
Interest expense	$ (15,651)	$ (13,615)
Interest income	59	2,139
Amortization of investment discount	136	2,964
Gain from sale of Priority Review Voucher		108,069
Other (expense) income, net	(72)	1,092
Total other (loss) income	$ (15,528)	$ 100,649

Basic and Diluted Net Loss Per Share (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands

3 Months Ended

Mar. 31, 2021

Mar. 31, 2020

Earnings Per Share [Abstract]

Net loss

$ (167,250)

$ (17,492)

Weighted-average common shares outstanding - basic

79,454

76,432

Effect of dilutive securities*

^[1]

Weighted-average common shares outstanding - diluted

79,454

76,432

Net loss per share - basic and diluted

$ (2.10)

$ (0.23)

[1]

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Basic and Diluted Net Loss Per Share (Parenthetical) (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Anti-dilutive securities excluded from computation of net loss per share	10.3	10.5

Summary of Aggregate Non-Cancelable Contractual Obligations Arising from Manufacturing Obligations (Detail) - Manufacturing Commitments Agreement [Member] - Catalent and Thermo [Member]
$ in Thousands

Mar. 31, 2021

USD ($)

Commitments And Contingencies [Line Items]

2021 (April - December)

$ 523,673

261,697

224,980

120,585

114,531

207,325

Total manufacturing commitments

$ 1,452,791

^[1]

[1]

Commitments and Contingencies - Additional Information (Detail) - Research and Development Expense [Member] $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Commitments And Contingencies [Line Items]
Derecognition of right of use asset	$ 22.8
Derecognition of lease liabilities	20.0
Recognition of loss	$ 2.8