Sarepta Therapeutics (SRPT) 10-Q 7 Aug 24 2024 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Aug. 02, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-14895
Entity Tax Identification Number	93-0797222
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	215 First Street
Entity Address, Address Line Two	Suite 415
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	274-4000
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	SRPT
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		95,366,334

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 383,622	$ 428,430
Short-term investments	1,076,852	1,247,820
Accounts receivable, net	359,997	400,327
Inventory	485,795	322,859
Manufacturing-related deposits and prepaids	302,627	102,181
Other current assets	74,743	77,714
Total current assets	2,683,636	2,579,331
Property and equipment, net	276,200	227,154
Right of use assets	124,001	129,952
Non-current inventory	204,691	191,368
Other non-current assets	135,729	136,771
Total assets	3,424,257	3,264,576
Current liabilities:
Accounts payable	107,417	164,918
Accrued expenses	350,404	314,997
Deferred revenue, current portion	122,036	50,416
Current portion of long-term debt	91,505	105,483
Other current liabilities	17,128	17,845
Total current liabilities	688,490	653,659
Long-term debt	1,134,810	1,132,515
Lease liabilities, net of current portion	143,601	140,965
Deferred revenue, net of current portion	325,000	437,000
Contingent consideration	48,200	38,100
Other non-current liabilities	7,087	3,000
Total liabilities	2,347,188	2,405,239
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 3,333,333 shares authorized; none issued and outstanding	0	0
Common stock, $0.0001 par value, 198,000,000 shares authorized; 95,282,600 and 93,731,831 issued and outstanding at June 30, 2024, and December 31, 2023, respectively	10	9
Additional paid-in capital	5,481,723	5,304,623
Accumulated other comprehensive (loss) income, net of tax	(1,030)	918
Accumulated deficit	(4,403,634)	(4,446,213)
Total stockholders’ equity	1,077,069	859,337
Total liabilities and stockholders’ equity	$ 3,424,257	$ 3,264,576

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
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, shares issued	95,282,600	93,731,831
Common stock, shares outstanding	95,282,600	93,731,831

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues:
Products, net	$ 360,548	$ 238,988	$ 720,032	$ 470,483
Type of Revenue [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Collaboration and other	$ 2,383	$ 22,250	$ 56,363	$ 44,255
Total revenues	362,931	261,238	776,395	514,738
Cost and expenses:
Cost of sales (excluding amortization of in-licensed rights)	44,545	34,124	95,104	69,141
Research and development	179,690	241,890	380,086	487,569
Selling, general and administrative	138,796	118,564	265,799	229,278
Amortization of in-licensed rights	601	179	1,202	357
Total cost and expenses	363,632	394,757	742,191	786,345
Operating (loss) income	(701)	(133,519)	34,204	(271,607)
Other income (loss), net:
Other income, net	14,278	16,934	20,821	29,641
Gain from sale of Priority Review Voucher	0	102,000	0	102,000
Loss on debt extinguishment	0	0	0	(387,329)
Total other income (loss), net	14,278	118,934	20,821	(255,688)
Income (loss) before income tax expense	13,577	(14,585)	55,025	(527,295)
Income tax expense	7,117	9,355	12,446	13,400
Net income (loss)	6,460	(23,940)	42,579	(540,695)
Other comprehensive income (loss):
Unrealized (losses) gains on investments, net of tax	(339)	(636)	(1,948)	609
Total other comprehensive (loss) income	(339)	(636)	(1,948)	609
Comprehensive income (loss)	$ 6,121	$ (24,576)	$ 40,631	$ (540,086)
Earnings (loss) per share:
Basic	$ 0.07	$ (0.27)	$ 0.45	$ (6.11)
Diluted	$ 0.07	$ (0.27)	$ 0.44	$ (6.11)
Weighted average number of shares of common stock used in computing earnings (loss) per share:
Basic	94,618	88,743	94,305	88,466
Diluted	99,144	88,743	99,129	88,466

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2022	$ 384,950	$ 9	$ 4,296,841	$ (1,664)	$ (3,910,236)
Balance (in shares) at Dec. 31, 2022		87,950,000
Exercise of options for common stock	22,808		22,808
Exercise of options for common stock, shares		267,000
Vest of restricted stock units		390,000
Issuance of common stock under employee stock purchase plan	5,229		5,229
Issuance of common stock under employee stock purchase plan, shares		77,000
Stock-based compensation	41,250		41,250
Issuance Of Common Stock For Conversion Of 2024 Notes Value	693,377		693,377
Issuance of common stock for conversion of 2024 Notes, Shares		4,456,000
Partial settlement of capped call share options for 2024 Notes	80,645		80,645
Unrealized gains from available-for-sale securities, net of tax	1,245			1,245
Net Income (Loss)	(516,755)				(516,755)
Balance at Mar. 31, 2023	712,749	$ 9	5,140,150	(419)	(4,426,991)
Balance (in shares) at Mar. 31, 2023		93,140,000
Balance at Dec. 31, 2022	384,950	$ 9	4,296,841	(1,664)	(3,910,236)
Balance (in shares) at Dec. 31, 2022		87,950,000
Partial settlement of capped call share options for 2024 Notes	80,645
Net Income (Loss)	(540,695)
Balance at Jun. 30, 2023	741,411	$ 9	5,193,388	(1,055)	(4,450,931)
Balance (in shares) at Jun. 30, 2023		93,274,000
Balance at Mar. 31, 2023	712,749	$ 9	5,140,150	(419)	(4,426,991)
Balance (in shares) at Mar. 31, 2023		93,140,000
Exercise of options for common stock	5,861		5,861
Exercise of options for common stock, shares		80,000
Vest of restricted stock units		54,000
Stock-based compensation	47,377		47,377
Unrealized gains from available-for-sale securities, net of tax	(636)			(636)
Net Income (Loss)	(23,940)				(23,940)
Balance at Jun. 30, 2023	741,411	$ 9	5,193,388	(1,055)	(4,450,931)
Balance (in shares) at Jun. 30, 2023		93,274,000
Balance at Dec. 31, 2023	859,337	$ 9	5,304,623	918	(4,446,213)
Balance (in shares) at Dec. 31, 2023		93,732,000
Exercise of options for common stock	15,579		15,579
Exercise of options for common stock, shares		207,000
Vest of restricted stock units		461,000
Issuance of common stock under employee stock purchase plan	6,561		6,561
Issuance of common stock under employee stock purchase plan, shares		90,000
Stock-based compensation	45,205		45,205
Unrealized gains from available-for-sale securities, net of tax	(1,609)			(1,609)
Net Income (Loss)	36,119				36,119
Balance at Mar. 31, 2024	961,192	$ 9	5,371,968	(691)	(4,410,094)
Balance (in shares) at Mar. 31, 2024		94,490,000
Balance at Dec. 31, 2023	859,337	$ 9	5,304,623	918	(4,446,213)
Balance (in shares) at Dec. 31, 2023		93,732,000
Partial settlement of capped call share options for 2024 Notes	0
Net Income (Loss)	42,579
Balance at Jun. 30, 2024	1,077,069	$ 10	5,481,723	(1,030)	(4,403,634)
Balance (in shares) at Jun. 30, 2024		95,283,000
Balance at Mar. 31, 2024	961,192	$ 9	5,371,968	(691)	(4,410,094)
Balance (in shares) at Mar. 31, 2024		94,490,000
Exercise of options for common stock	39,918	$ 1	39,917
Exercise of options for common stock, shares		468,000
Vest of restricted stock units		131,000
Stock-based compensation	55,654		55,654
Issuance Of Common Stock For Conversion Of 2024 Notes Value	14,184		14,184
Issuance of common stock for conversion of 2024 Notes, Shares		194,000
Unrealized gains from available-for-sale securities, net of tax	(339)			(339)
Net Income (Loss)	6,460				6,460
Balance at Jun. 30, 2024	$ 1,077,069	$ 10	$ 5,481,723	$ (1,030)	$ (4,403,634)
Balance (in shares) at Jun. 30, 2024		95,283,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024		Jun. 30, 2023
Cash flows from operating activities:
Net income (loss)	$ 42,579		$ (540,695)
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation and amortization	17,463		22,097
Reduction in the carrying amounts of the right of use assets	7,964		6,811
Non-cash interest expense	2,501		2,688
Stock-based compensation	91,174		88,627
Accretion of investment discount, net	(22,859)		(20,245)
Non-cash change in the fair value of contingent consideration	10,100		(800)
Loss on debt extinguishment	0		387,329
Gain from sale of Priority Review Voucher	0		(102,000)
Other	(1,067)		645
Changes in operating assets and liabilities, net:
Net decrease (increase) in accounts receivable, net	40,330		(22,180)
Net (increase) decrease in manufacturing-related deposits and prepaids	(203,344)		1,378
Net increase in inventory	(162,972)		(26,998)
Net decrease in other assets	6,627		9,637
Net decrease in deferred revenue	(40,380)		(44,255)
Net decrease in accounts payable, accrued expenses, lease liabilities and other liabilities	(15,250)		(93,669)
Net cash used in operating activities	(227,134)		(331,630)
Cash flows from investing activities:
Purchase of property and equipment	(61,611)		(27,394)
Purchase of available-for-sale securities	(547,282)		(829,799)
Maturity and sale of available-for-sale securities	739,161		864,458
Purchase of intangible assets	(10,000)		(139)
Proceeds from sale of Priority Review Voucher	0		102,000
Net cash provided by investing activities	120,268		109,126
Cash flows from financing activities:
Proceeds from exercise of stock options and purchase of stock under the Employee Stock Purchase Program	62,058		33,898
Partial settlement of capped call share options for 2024 Notes	0		80,645
Debt conversion costs for 2024 Notes	0		(6,887)
Net cash provided by financing activities	62,058		107,656
Decrease in cash, cash equivalents and restricted cash	(44,808)		(114,848)
Cash, cash equivalents and restricted cash:
Beginning of period	444,009		985,801
End of period	399,201		870,953
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	383,622		851,929
Restricted cash in other assets	15,579	[1]	19,024
Total cash, cash equivalents and restricted cash	399,201		870,953
Supplemental disclosure of cash flow information:
Cash paid during the period for income taxes	7,990		5,991
Cash paid during the period for interest	7,981		7,817
Supplemental schedule of non-cash activities:
Intangible assets and property and equipment included in accounts payable and accrued expenses	30,483		20,928
Lease liabilities arising from obtaining right of use assets	2,018		75,875
Common stock issued for exchange of 2024 Notes	14,184		693,377
Capitalized stock-based compensation and depreciation as inventory	$ 13,287		$ 0
[1] * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ 6,460	$ 36,119	$ (23,940)	$ (516,755)	$ 42,579	$ (540,695)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

ORGANIZATION AND NATURE OF BUSI

ORGANIZATION AND NATURE OF BUSINESS	6 Months Ended
	Jun. 30, 2024
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 has developed multiple approved products for the treatment of Duchenne muscular dystrophy (“Duchenne”) and is developing potential therapeutic candidates for a broad range of diseases and disorders, including Duchenne, Limb-girdle muscular dystrophies (“LGMDs”) and other neuromuscular and central nervous system disorders. The Company's 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. Indicated for the treatment of Duchenne in patients who have a confirmed mutation of the dystrophin gene that is amenable to exon 51, exon 53 and exon 45 skipping, respectively, EXONDYS 51, VYONDYS 53 and AMONDYS 45 (collectively, the “PMO Products”) use the Company’s phosphorodiamidate morpholino oligomer (“PMO”) chemistry and exon-skipping technology to skip exon 51, exon 53 and exon 45 of the dystrophin gene. Exon skipping is intended to promote the production of an internally truncated but functional dystrophin protein. ELEVIDYS (delandistrogene moxeparvovec-rokl), approved by the FDA on June 20, 2024, is an adeno-associated virus-based gene therapy for the treatment of ambulatory pediatric patients at least 4 years old with Duchenne with a confirmed mutation in the Duchenne gene. ELEVIDYS is also approved for non-ambulatory patients under the accelerated approval pathway. ELEVIDYS was previously granted accelerated approval by the FDA on June 22, 2023 for the treatment of ambulatory pediatric patients aged 4 through 5 years with Duchenne with a confirmed mutation in the Duchenne gene. ELEVIDYS is contraindicated in patients with any deletion in exon 8 and/or exon 9 in the Duchenne gene. As of June 30, 2024, the Company had approximately $ 1,476.1 million of cash, cash equivalents, restricted cash and investments, consisting of $ 383.6 million of cash and cash equivalents, $ 1,076.9 million of short-term investments and $ 15.6 million of non-current restricted cash. 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 additional cash resources through public or private debt and equity financings, seek funded research and development arrangements and additional government contracts and establish collaborations with or license its technology to other companies.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES 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 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 consolidated financial statements and related notes for the year ended December 31, 2023 which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed with the U.S. Securities and Exchange Commission on February 28, 2024. The results for the three and six months ended June 30, 2024 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, revenues, 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 cash held at financial institutions, cash equivalents, investments and accounts receivable, net, from customers. As of June 30, 2024, the Company’s cash was concentrated at three financial institutions, 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. The Company also purchases commercial paper, government and government agency bonds, corporate bonds and certificates of deposit issued by highly rated corporations, financial institutions and governments and limits the amount of credit exposure to any one issuer. These amounts may at times exceed federally insured limits. The Company has not experienced any credit losses related to these financial instruments and does not believe to be exposed to any significant credit risk related to these instruments. As of June 30, 2024 , three entities accounted for 33 % , 28 % and 15 % of accounts receivable, net, respectively. As of December 31, 2023, four entities accounted for 40 % , 19 % , 19 % and 12 % of accounts receivable, net, respectively. As of June 30, 2024 , the Company believes its largest customers are of high credit quality and has not experienced any material credit losses related to such customers. 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, 2023. There have not been any material changes to the Company's accounting policies or recent accounting pronouncements that could have a material impact through June 30, 2024 .

LICENSE AND COLLABORATION AGREE

LICENSE AND COLLABORATION AGREEMENTS	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
LICENSE AND COLLABORATION AGREEMENTS	3. LICENSE AND COLLABORATION AGREEMENTS F. Hoffman-La Roche Ltd. For the three and six months ended June 30, 2023, the Company recognized $ 22.3 million and $ 44.3 million, respectively, of collaboration revenue associated with the license, collaboration and option agreement (the “Roche Agreement”) with F. Hoffman-La Roche Ltd. (“Roche”) related to the amortization of the single, combined performance obligation, with no such activity for the corresponding periods ended June 30, 2024. Under the Roche Agreement, the Company has granted Roche options to acquire ex-U.S. rights to certain future Duchenne development programs (the “Options”) in exchange for separate option exercise payments, milestone and royalty considerations, and cost-sharing provisions. These Options were accounted for as material rights related to individual programs and recorded in deferred revenue at the inception of the Roche Agreement. The value assigned to the material rights is included in deferred revenue until such rights expire or are exercised. On February 12, 2024, Roche declined to exercise its optional rights related to one external, early stage development program, which resulted in the immediate recognition of $ 48.0 million of collaboration revenue for the six months ended June 30, 2024. As of June 30, 2024 and December 31, 2023, the Company had total deferred revenue of $ 447.0 million and $ 487.4 million, primarily related to the separate material rights for the Options associated with the Roche Agreement, of which $ 122.0 million and $ 50.4 million were classified as current, respectively. 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 and six months ended June 30, 2024, costs reimbursable by Roche and reflected as a reduction to operating expenses were $ 17.9 million and $ 39.6 million, respectively. For the three and six months ended June 30, 2023, costs reimbursable by Roche and reflected as a reduction to operating expenses were $ 28.2 million and $ 48.5 million, respectively. As of June 30, 2024 and December 31, 2023, there were $ 19.9 million and $ 29.8 million, respectively, of collaboration and other receivables included in other current assets on the unaudited condensed consolidated balance sheets. In accordance with the Roche Agreement, the Company agreed to enter into a supply agreement with Roche in order to supply them with clinical and commercial batches of ELEVIDYS (the “Supply Agreement”). While the Supply Agreement is in the process of being negotiated, the Company has delivered batches of commercial ELEVIDYS supply to Roche that were agreed upon on a purchase order-by-purchase order basis. For the six months ended June 30, 2024, the Company recognized $ 5.8 million of contract manufacturing revenue related to these shipments, with no similar activity for the six months ended June 30, 2023. There was no similar activity in contract manufacturing revenue for either the three months ended June 30, 2024 or 2023. This revenue is included in collaboration and other revenues in the unaudited condensed consolidated statements of comprehensive income (loss). For the six months ended June 30, 2024, the Company recognized $ 1.7 million of inventory costs related to these shipments, which is included in cost of sales (excluding amortization of in-licensed rights) in the unaudited condensed consolidated statements of comprehensive income (loss). For the three and six months ended June 30, 2024, the Company recognized $ 2.4 million and $ 2.6 million, respectively, of royalty revenue from sales of ELEVIDYS by Roche, with no similar activity for the same periods of 2023. 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 pre-clinical 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 $ 34.8 million in research milestone payments. Under these agreements, there are $ 121.8 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 royalty payments based on the net sales of the developed products upon commercialization. For the three and six months ended June 30, 2023 , the Company recognized $ 7.5 million of up-front payments related to an exercised option as research and development expense. During the three and six months ended June 30, 2024 , the Company did no t exercise any options, nor did any additional 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 June 30, 2024, the Company may be obligated to make up to $ 2.8 billion of future development, regulatory, commercial and up-front royalty payments associated with its collaboration and license agreements. These obligations exclude potential future option and milestone payments for options that have yet to be exercised within research and option agreements entered into by the Company as of June 30, 2024, which are discussed above. For the three and six months ended June 30, 2023, the Company recognized up-front, development milestone and other expenses of $ 7.6 million and $ 8.1 million, respectively, as research and development expense in the accompanying unaudited condensed consolidated statements of comprehensive income (loss), with no similar activity for the three and six months ended June 30, 2024 .

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	4. 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. During the six months ended June 30, 2024 , there were no transfers into or out of Level 3. 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 the valuation techniques it utilizes to determine such fair value: Fair Value Measurement as of June 30, 2024 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 100,859 $ 100,859 $ — $ — Commercial paper 26,866 — 26,866 — Government and government agency bonds 854,254 — 854,254 — Corporate bonds 180,781 — 180,781 — Strategic investments 7,606 6,606 — 1,000 Certificates of deposit 53,130 — 53,130 — Total assets $ 1,223,496 $ 107,465 $ 1,115,031 $ 1,000 Liabilities Contingent consideration $ 48,200 $ — $ — $ 48,200 Total liabilities $ 48,200 $ — $ — $ 48,200 Fair Value Measurement as of December 31, 2023 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 63,919 $ 63,919 $ — $ — Commercial paper 113,362 — 113,362 — Government and government agency bonds 1,001,137 — 1,001,137 — Corporate bonds 130,380 — 130,380 — Strategic investments 6,527 5,527 — 1,000 Certificates of deposit 56,621 — 56,621 — Total assets $ 1,371,946 $ 69,446 $ 1,301,500 $ 1,000 Liabilities Contingent consideration $ 38,100 $ — $ — $ 38,100 Total liabilities $ 38,100 $ — $ — $ 38,100 The Company’s assets with a fair value categorized as Level 1 within the fair value hierarchy include money market funds and the Company's strategic investment in a biotechnology company listed on the Nasdaq Global Market. The Company's assets with a fair value categorized as Level 2 within the fair value hierarchy consist of commercial paper, government and government agency bonds, corporate bonds and certificates of deposit. These assets have been initially valued at the transaction price and subsequently valued at the end of each reporting period utilizing third-party pricing services. The Company uses observable market inputs to determine value, which primarily consist of reportable trades. Certain of the short-term investments with maturities of less than three months at the date of acquisition are presented as cash equivalents on the unaudited condensed consolidated balance sheets as of June 30, 2024. The Company’s assets with a fair value categorized as Level 3 within the fair value hierarchy consist of a strategic investment in a private biotechnology company whose fair value measurement was based upon significant inputs not observable in the market and therefore represented a Level 3 measurement. At the end of each reporting period, the fair value of the Company's strategic investments that are not listed securities are adjusted if the issuers were to issue similar or identical securities or when there is a triggering event for impairment. There were no valuation measurement events related to the fair value of the Company's Level 3 strategic investments during the six months ended June 30, 2024 or 2023, as no impairment indicators were identified nor were similar securities issued. The Company’s contingent consideration liability with a fair value categorized as Level 3 within the fair value hierarchy relates 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 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. 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. The following table represents a roll-forward of the fair value of Level 3 financial liabilities for the periods indicated: As of As of (in thousands) Fair value, as of beginning of period $ 38,100 $ 36,900 Change in estimated fair value 10,100 — Liabilities terminated — ( 800 ) Fair value, as of end of period $ 48,200 $ 36,100 For the six months ended June 30, 2024, the Company recorded an increase of $ 10.1 million to account for the change in fair value of the Company's existing contingent consideration liabilities. These changes, which are recorded through earnings, were a result of updates made to certain inputs and assumptions impacting the probability-weighted expected cash flows, principally the probability of success of the underlying programs and the discount rate utilized to determine the present value of future payments to be made. As of June 30, 2024, the contingent consideration was recorded as a long-term liability on the Company's unaudited condensed consolidated balance sheets. For the six months ended June 30, 2023, a decrease of $ 0.8 million was recorded to account for the termination of a license agreement with an academic institution that had met the definition of a derivative. The carrying amounts reported in the unaudited condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximated fair value because of the immediate or short-term maturity of these financial instruments. For fair value information related to the Company's debt facilities, please read Note 10, Indebtedness.

CASH, CASH EQUIVALENTS AND MARK

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	6 Months Ended
	Jun. 30, 2024
Cash and Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES	5. 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 As of (in thousands) Money market funds $ 100,859 $ 63,919 Government and government agency bonds 29,058 — Corporate bonds 9,121 — Commercial paper — 53,680 Total $ 139,038 $ 117,599 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 both June 30, 2024 and December 31, 2023 was approximate ly five months . The following tables summarize the Company ’s cash, cash equivalents and short-term investments for each of the periods indicated: As of June 30, 2024 Amortized Gross Gross Fair (in thousands) Cash and money market funds $ 345,443 $ — $ — $ 345,443 Commercial paper 26,866 — — 26,866 Government and government agency bonds 855,148 — ( 894 ) 854,254 Corporate bonds 180,890 6 ( 115 ) 180,781 Certificates of deposit 53,130 — — 53,130 Total cash, cash equivalents and investments $ 1,461,477 $ 6 $ ( 1,009 ) $ 1,460,474 As reported: Cash and cash equivalents $ 383,623 $ — $ ( 1 ) $ 383,622 Short-term investments 1,077,854 6 ( 1,008 ) 1,076,852 Total cash, cash equivalents and investments $ 1,461,477 $ 6 $ ( 1,009 ) $ 1,460,474 As of December 31, 2023 Amortized Gross Gross Fair (in thousands) Cash and money market funds $ 374,750 $ — $ — $ 374,750 Commercial paper 113,362 — — 113,362 Government and government agency bonds 1,000,302 1,006 ( 171 ) 1,001,137 Corporate bonds 130,270 118 ( 8 ) 130,380 Certificates of deposit 56,621 — — 56,621 Total cash, cash equivalents and investments $ 1,675,305 $ 1,124 $ ( 179 ) $ 1,676,250 As reported: Cash and cash equivalents $ 428,430 $ — $ — $ 428,430 Short-term investments 1,246,875 1,124 ( 179 ) 1,247,820 Total cash, cash equivalents and investments $ 1,675,305 $ 1,124 $ ( 179 ) $ 1,676,250

PRODUCT REVENUES, NET, ACCOUNTS

PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE, NET, AND RESERVES FOR PRODUCT REVENUES	6 Months Ended
	Jun. 30, 2024
Receivables, Net, Current [Abstract]
PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE, NET, AND RESERVES FOR PRODUCT REVENUES	6. PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE, NET, AND RESERVES FOR PRODUCT REVENUES Net product revenues, which includes revenues associated with the PMO Products and ELEVIDYS, consisted of the following: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) PMO Products United States $ 204,248 $ 203,895 $ 393,915 $ 404,346 Rest of World 34,579 35,093 70,460 66,137 Total PMO product revenues, net $ 238,827 $ 238,988 $ 464,375 $ 470,483 ELEVIDYS United States 121,721 — 255,657 — Total ELEVIDYS product revenue, net $ 121,721 $ — $ 255,657 $ — Total product revenues, net $ 360,548 $ 238,988 $ 720,032 $ 470,483 For the three and six months ended June 30, 2024 and 2023 , no individual country outside the U.S. exceeded 10 % of total net product revenues. The following table summarizes the Company's net product revenues, by customer, for those customers that exceeded 10 % for the periods indicated: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 Product revenues, net Customer 1 35 % 47 % 35 % 48 % Customer 2 21 % 33 % 20 % 32 % As of June 30, 2024 and December 31, 2023, the Company's accounts receivable, net were $ 360.0 million and $ 400.3 million, respectively, both of which were related to product sales, net of discounts and allowances. As of June 30, 2024 , 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 65 to 90 days. Outside of the U.S., the majority of the Company’s customers have payment terms ranging between 90 and 150 days. Please refer to Note 2, Summary of Significant Accounting Policies for discussion of the credit risk associated with accounts receivable, net. 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, 2023 $ 27,486 $ 98,194 $ 3,831 $ 35,261 $ 164,772 Provision 41,935 72,684 8,585 35,527 158,731 Adjustments relating to prior periods 783 ( 5,171 ) — ( 88 ) ( 4,476 ) Payments/credits ( 54,393 ) ( 62,647 ) ( 8,462 ) ( 33,210 ) ( 158,712 ) Balance, as of June 30, 2024 $ 15,811 $ 103,060 $ 3,954 $ 37,490 $ 160,315 Chargebacks Rebates Prompt Pay Other Accruals Total (in thousands) Balance, as of December 31, 2022 $ 417 $ 67,493 $ 3,343 $ 23,445 $ 94,698 Provision 6,287 60,824 7,228 32,220 106,559 Adjustments relating to prior periods — ( 3,437 ) — — ( 3,437 ) Payments/credits ( 6,434 ) ( 45,592 ) ( 6,976 ) ( 24,820 ) ( 83,822 ) Balance, as of June 30, 2023 $ 270 $ 79,288 $ 3,595 $ 30,845 $ 113,998 The following table summarizes the total reserves above included in the Company’s unaudited condensed consolidated balance sheets for each of the periods indicated: As of As of (in thousands) Reduction to accounts receivable $ 55,663 $ 64,697 Component of accrued expenses 104,652 100,075 Total reserves $ 160,315 $ 164,772

INVENTORY

INVENTORY	6 Months Ended
	Jun. 30, 2024
Inventory Disclosure [Abstract]
INVENTORY	7. INVENTORY The following table summarizes the components of the Company’s inventory for each of the periods indicated: As of As of (in thousands) Raw materials $ 167,201 $ 133,963 Work in progress 470,381 318,458 Finished goods 52,904 61,806 Total inventory $ 690,486 $ 514,227 No material inventory reserves existed as of June 30, 2024 or December 31, 2023. The Company classifies inventory associated with its PMO Products as non-current inventory when consumption of the inventory is expected beyond the Company's normal PMO Product inventory operating cycle of two years. Non-current inventory consists of raw materials and work in progress associated with the PMO Products. The following table summarizes the balance sheet classification of the Company's inventory for each of the periods indicated: As of As of (in thousands) Balance sheet classification Inventory $ 485,795 $ 322,859 Non-current inventory 204,691 191,368 Total inventory $ 690,486 $ 514,227

OTHER ASSETS

OTHER ASSETS	6 Months Ended
	Jun. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
OTHER ASSETS	8. OTHER ASSETS The following table summarizes the Company’s other current assets for each of the periods indicated: As of As of (in thousands) Collaboration and other receivables $ 19,869 $ 29,786 Prepaid maintenance services 14,266 11,281 Prepaid clinical and pre-clinical expenses 12,356 10,280 Tax-related receivables and prepaids 8,415 6,862 Interest receivable 3,979 2,731 Prepaid insurance 3,932 3,352 Prepaid commercial expenses 3,684 2,729 Other 8,242 10,693 Total other current assets $ 74,743 $ 77,714 The following table summarizes the Company’s other non-current assets for each of the periods indicated: As of As of (in thousands) Manufacturing-related deposits and prepaids $ 77,102 $ 74,204 Intangible assets, net 28,252 29,620 Restricted cash* 15,579 15,579 Strategic investments 7,606 6,527 Prepaid maintenance services 4,046 5,466 Other 3,144 5,375 Total other non-current assets $ 135,729 $ 136,771 * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

ACCRUED EXPENSES

ACCRUED EXPENSES	6 Months Ended
	Jun. 30, 2024
Payables and Accruals [Abstract]
ACCRUED EXPENSES	9. ACCRUED EXPENSES The following table summarizes the Company’s accrued expenses for each of the periods indicated: As of As of (in thousands) Product revenue related reserves $ 104,652 $ 100,075 Accrued contract manufacturing costs 77,451 33,024 Accrued employee compensation costs 50,023 78,732 Accrued clinical and pre-clinical costs 36,221 34,669 Accrued professional fees 22,885 17,187 Accrued fixed assets 21,163 3,231 Accrued income taxes 18,186 13,766 Accrued royalties 7,724 12,070 Accrued interest 4,368 4,395 Accrued research expenses 2,737 2,441 Other 4,994 4,032 Total accrued expenses $ 350,404 $ 314,997

INDEBTEDNESS

INDEBTEDNESS	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
INDEBTEDNESS	10. INDEBTEDNESS 2024 Convertible Notes and 2017 Capped Call Transactions On November 14, 2017, the Company issued $ 570.0 million aggregate principal amount of senior convertible notes due on November 15, 2024 (the “2024 Notes”) and, simultaneously, entered into capped call transactions with counterparties intended to minimize the impact of potential dilution upon conversion of the 2024 Notes (the “2017 Capped Calls”). On September 14, 2022, the Company entered into separate, privately negotiated transactions to repurchase a portion of the outstanding 2024 Notes. The holders exchanged $ 150.6 million in aggregate principal value of 2024 Notes held by them for an aggregate payment of $ 248.6 million for full settlement of the principal value and accrued interest on such date. As a result of the repurchases, the Company entered into agreements with the 2017 Capped Calls counterparties to terminate a corresponding portion of the 2017 Capped Calls and received $ 26.3 million in cash. On March 2, 2023, the Company entered into separate, privately negotiated exchange agreements with certain holders of the outstanding 2024 Notes. The holders exchanged $ 313.5 million in aggregate principal value of the 2024 Notes held by them for 4.5 million shares of the Company’s common stock. As a result of the exchange, the Company entered into agreements with the counterparties to the 2017 Capped Calls to terminate a portion of the 2017 Capped Calls and received approximately $ 80.6 million in cash. In June 2024, certain existing holders elected to convert $ 14.2 million in aggregate principal amount of the 2024 Notes into approximately 0.2 million shares of the Company’s common stock. As the conversions were completed under the original terms of the 2024 Notes, there is no gain or loss impact on the accompanying unaudited condensed consolidated statements of comprehensive income (loss). The capped call options related to the shares underlying the conversion are required to be settled at the scheduled maturity date of the 2024 Notes. For additional details about the 2024 Notes, please read Note 13, Indebtedness to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Total Debt Obligations As of June 30, 2024 and December 31, 2023, the Company recorded approximately $ 1,226.3 million and $ 1,238.0 million as debt on the unaudited condensed consolidated balance sheets, respectively, with the 2024 Notes balance recorded as a current liability for both periods. The following table summarizes the Company’s debt facilities for each of the periods indicated: As of As of (in thousands) Principal amount of the 2024 Notes $ 91,641 $ 105,847 Principal amount of the 2027 Notes 1,150,000 1,150,000 Unamortized discount - debt issuance costs of 2024 Notes ( 136 ) ( 364 ) Unamortized discount - debt issuance costs of 2027 Notes ( 15,190 ) ( 17,485 ) Total carrying value of debt facilities $ 1,226,315 $ 1,237,998 Fair value of 2024 Notes $ 206,338 $ 144,833 Fair value of 2027 Notes 1,485,409 1,172,276 Total fair value of debt facilities $ 1,691,747 $ 1,317,109 For each of the three months ended June 30, 2024 and 2023, contractual interest expense from debt facilities was $ 5.2 million, inclusive of $ 1.3 million and $ 1.2 million of amortization of debt discounts, respectively. For the six months ended June 30, 2024 and 2023, contractual interest expense from debt facilities was $ 10.5 million and $ 11.5 million, inclusive of $ 2.5 million and $ 2.7 million of amortization of debt discounts, respectively. The fair value of the 1.25% convertible senior notes due on September 15, 2027 (“2027 Notes”) and the 2024 Notes is based on open market trades and is classified as Level 1 in the fair value hierarchy. The following table summarizes the total principal and contractual interest payments due under the Company’s debt arrangements: As of June 30, 2024 Principal Interest Total Payments (in thousands) 2024 (July-December) $ 91,641 $ 7,898 $ 99,539 2025 — 14,375 14,375 2026 — 14,375 14,375 2027 1,150,000 14,375 1,164,375 Total payments $ 1,241,641 $ 51,023 $ 1,292,664

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	11. STOCK-BASED COMPENSATION The following table summarizes the Company’s stock awards granted for each of the periods indicated: For the Three Months Ended June 30, For the Six Months Ended June 30, 2024 2023 2024 2023 Grants Weighted Grants Weighted Grants Weighted Grants Weighted Stock options 5,100 $ 72.37 54,575 $ 66.82 321,478 $ 67.63 1,084,924 $ 72.50 Restricted stock units 54,905 (1) $ 138.91 33,752 $ 121.27 1,216,890 (1) $ 129.05 1,109,663 (2) $ 153.89 (1) Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2024 are 8,860 and 97,460 shares with performance conditions (“March 2024 PSUs”), respectively, which are related to the achievement of certain financial performance goals and regulatory approval of certain of the Company's product candidates. The expanded regulatory approval of ELEVIDYS in June 2024 resulted in the cliff-vesting of 44,300 of the 97,460 shares of the March 2024 PSUs during the three and six months ended June 30, 2024. As of June 30, 2024 , none of the performance conditions for the remaining 53,160 shares were probable of being achieved. Stock options and the remaining RSUs granted during the three and six months ended June 30, 2024 have only service-based criteria and vest over four years. (2) Included in the RSUs for the six months ended June 30, 2023 are 502,225 shares with performance conditions (the “March 2023 PSUs”), which are related to regulatory approval of ELEVIDYS and achievement of a certain financial performance target, both of which were achieved in 2023. Vesting of the March 2023 PSUs is contingent on the fulfillment of remaining service conditions. During the year ended December 31, 2022, the Company granted 38,500 RSUs with performance conditions (the “March 2022 PSUs”), which are related to regulatory approval of certain of the Company's product candidates. As a result of the expanded regulatory approval of ELEVIDYS in June 2024, a portion of the March 2022 PSUs became eligible for vesting. Vesting of these PSUs is contingent on the fulfillment of remaining service conditions. As of June 30, 2024, none of the remaining performance conditions were probable of being achieved. Stock-based Compensation Expense For the three months ended June 30, 2024 and 2023, total stock-based compensation expense was $ 50.5 million and $ 47.4 million, respectively. For the six months ended June 30, 2024 and 2023, total stock-based compensation expense was $ 91.2 million and $ 88.6 million, respectively. The following table summarizes stock-based compensation expense by grant type and by function included within the unaudited condensed consolidated statements of comprehensive income (loss): For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) Stock options $ 15,515 $ 21,135 $ 31,796 $ 44,965 Restricted stock units 37,808 25,037 65,335 41,177 Employee stock purchase plan 2,331 1,205 3,728 2,485 Subtotal $ 55,654 $ 47,377 $ 100,859 $ 88,627 Capitalized stock-based compensation costs* ( 5,172 ) — ( 9,685 ) — Total stock-based compensation expense included in expenses $ 50,482 $ 47,377 $ 91,174 $ 88,627 Research and development 19,806 21,577 36,079 37,990 Selling, general and administrative 30,676 25,800 55,095 50,637 Total stock-based compensation expense included in expenses $ 50,482 $ 47,377 $ 91,174 $ 88,627 * Prior to the six months ended June 30, 2024 , capitalized stock-based compensation costs were not material.

OTHER INCOME (LOSS), NET

OTHER INCOME (LOSS), NET	6 Months Ended
	Jun. 30, 2024
Other Income and Expenses [Abstract]
OTHER INCOME (LOSS), NET	12. OTHER INCOME (LOSS), NET The following table summarizes other income (loss), net f or each of the periods indicated: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) Accretion of investment discount, net $ 10,766 $ 12,786 $ 23,570 $ 22,825 Interest income 8,076 8,418 15,169 17,694 Interest expense ( 4,832 ) ( 5,224 ) ( 8,998 ) ( 11,547 ) Change in the fair value of contingent consideration — 800 ( 10,100 ) 800 Other, net 268 154 1,180 ( 131 ) Other income, net $ 14,278 $ 16,934 $ 20,821 $ 29,641 Gain from sale of Priority Review Voucher — 102,000 — 102,000 Loss on debt extinguishment — — — ( 387,329 ) Total other income (loss), net $ 14,278 $ 118,934 $ 20,821 $ ( 255,688 )

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
INCOME TAXES	13. INCOME TAXES During the three and six months ended June 30, 2024 , the Company recorded an income tax provision of $ 7.1 million and $ 12.4 million, respectively. The effective tax rate for the six months ended June 30, 2024 was 22.6 % . The income tax provision primarily relates to the current tax provision on taxable profits, including in certain states which restrict the amount of net operating loss carryforwards which may be utilized to offset taxable income. The Company continues to maintain a valuation allowance on its worldwide deferred tax assets with the exception of deferred tax assets in certain foreign jurisdictions, as it has concluded that it is more likely than not that these deferred tax assets will not be realized. During the three and six months ended June 30, 2023 , the Company recorded an income tax provision of $ 9.4 million and $ 13.4 million, respectively. The effective tax rate for the six months ended June 30, 2023 was ( 2.5 %) . For tax years beginning on or after January 1, 2022, the Tax Cuts and Jobs Act of 2017 eliminates the option to currently deduct research and development expenses and requires taxpayers to capitalize and amortize the costs over five years for research activities performed in the U.S. and 15 years for research activities performed outside the U.S. The requirement to capitalize research and development costs for tax purposes resulted in the Company having taxable profits and recording federal and state tax expense of $ 2.9 million and $ 10.5 million, respectively. The state tax expense of $ 10.5 million is primarily related to state taxable income, partially offset by net operating loss carryforwards.

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	14. EARNINGS (LOSS) PER SHARE Basic earnings per share is computed by dividing net income by the weighted-average number of shares of common stock outstanding. Diluted earnings per share is computed by dividing net income by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding. The following table sets forth the computation of basic and diluted earnings (loss) per common share: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands, except per share amounts) Numerator: Net income (loss) - basic $ 6,460 $ ( 23,940 ) $ 42,579 $ ( 540,695 ) Add: interest expense, net of tax, on the Company's convertible debt 340 — 769 — Net income (loss) - diluted $ 6,800 $ ( 23,940 ) $ 43,348 $ ( 540,695 ) Denominator: Weighted-average common shares outstanding, basic 94,618 88,743 94,305 88,466 Effect of dilutive securities: Common stock issuable under the Company's equity incentive plans 3,095 — 3,388 — Common stock issuable under the Company's convertible debt 1,431 — 1,436 — Weighted-average common shares outstanding, diluted 99,144 88,743 99,129 88,466 Earnings (loss) per common share, basic $ 0.07 $ ( 0.27 ) $ 0.45 $ ( 6.11 ) Earnings (loss) per common share, diluted $ 0.07 $ ( 0.27 ) $ 0.44 $ ( 6.11 ) The following table summarizes potential shares of common stock that were excluded from the computation of diluted earnings per share as they were anti-dilutive: As of As of (in thousands) Common stock issuable under the Company's equity incentive plans 2,879 (1) 12,316 (2) Common stock issuable under the Company's convertible debt 8,100 9,542 Total number of potentially issuable common stock 10,979 21,858 (1) As of June 30, 2024, the anti-dilutive common stock issuable under the Company's equity incentive plans excludes 1.2 million shares that are dilutive but have performance or market conditions that were not met as of the end of the period. (2) As of June 30, 2023, the anti-dilutive common stock issuable under the Company's equity incentive plans includes 1.2 million shares that have performance or market conditions that were not met as of the end of the period because these were anti-dilutive as the Company was in a net loss position at the end of the period .

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2024
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 (in thousands) 2024 (July-December) $ 757,166 2025 230,756 2026 108,260 2027 77,630 2028 72,343 Total manufacturing commitments* $ 1,246,155 * Total manufacturing commitments include the Catalent, Inc. (“Catalent”) manufacturing and supply agreement, for which the Company has ROU assets and lease liabilities recorded on the unaudited condensed consolidated balance sheets as of June 30, 2024 . For more information related to the Company’s manufacturing and supply agreements, please read Note 16, Subsequent Events included herein and Note 21, Commitments and Contingencies to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Litigation In the normal course of business, the Company from time to time is named as a party to various legal claims, actions and complaints, which have included and may include matters involving securities, employment, intellectual property, arising from the use of therapeutics utilizing its technology, or others. The Company records a loss contingency reserve for a legal proceeding when it considers the potential loss probable, and it can reasonably estimate the amount of the loss or determine a probable range of loss. The Company provides disclosure when it considers a loss reasonably possible or when it determines that a loss in excess of a reserve is reasonably possible. The Company provides an estimate of such reasonably possible losses or an aggregate range of such reasonably possible losses, unless the Company believes that such an estimate cannot be made. The Company has not recorded any material accruals for loss contingencies, and in management's opinion, no material range of loss is estimable for the matters described below as of June 30, 2024. On September 15, 2020, REGENXBIO INC. (“Regenx”) and the Trustees of the University of Pennsylvania (“U-Penn”) filed a lawsuit against the Company and Sarepta Therapeutics Three, LLC, 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 the patented cultured host cell technology allegedly used to make adeno-associated virus (“AAV”) gene therapy products, including SRP-9001 (approved June 22, 2023 in the U.S. as ELEVIDYS®). 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 the ‘617 Patent asserted by Regenx. Plaintiffs seek injunctive relief, a judgment of infringement and willful infringement, damages that are no less than a reasonable royalty (treble damages), attorneys’ fees and costs, and such other relief as the court deems just and proper. On January 5, 2024, the Court granted Sarepta’s motion for summary judgment on the grounds that the asserted claims of Regenx’s ‘617 Patent are invalid because they cover patent ineligible subject matter under 35 U.S.C. § 101. On January 12, 2024, the Court entered judgment and closed the case. Plaintiffs have appealed to the U.S. Court of Appeals for the Federal Circuit. On June 20, 2023, Regenx and U-Penn commenced a second patent infringement lawsuit against Sarepta and its contract manufacturer, Catalent asserting patent alleged infringement of U. S. Patent No. 11,680,274 (“the ’274 Patent”). In the second lawsuit, Regenx and U-Penn allege that Sarepta and Catalent’s manufacture, use and commercial launch of ELEVIDYS® (SRP-9001) infringe the ’274 Patent. Sarepta answered the complaint on August 10, 2023, and a case schedule has been set with a trial commencing on November 17, 2025. On February 21, 2024, Sarepta submitted a petition for Inter Partes Review ("IPR") for filing with the Patent Trial and Appeal Board ("PTAB") at the USPTO. The petition seeks to invalidate the ‘274 Patent. On March 20, 2024, the district court stayed the litigation pending the PTAB’s determination on the IPR. On July 13, 2021, Nippon Shinyaku Co., Ltd. (“Nippon Shinyaku” or “NS”) filed a lawsuit against the Company in the U.S. District Court for the District of Delaware. NS asserted a claim for breach of contract arising from Sarepta filing seven petitions for Inter Partes Review (“IPR Petitions”) with the PTAB at the USPTO in which Sarepta sought to invalidate certain NS patents concerning exon 53 skipping technology (U.S. Patent Nos. 9,708,361, 10,385,092, 10,407,461, 10,487,106, 10,647,741, 10,662,217, and 10,683,322, respectively, and collectively the “NS Patents”). In addition, NS asserted claims for patent infringement and willful infringement of each of the NS Patents allegedly arising from Sarepta’s activities, including the sale of, its exon 53 skipping product, VYONDYS 53 (golodirsen). NS further sought a determination of non-infringement by NS alleged to arise from NS’s activities, including the sale of, its exon 53 skipping product, Viltepso (viltolarsen) and invalidity of certain patents licensed to the Company from the University of Western Australia ("UWA") (U.S. Patent Nos. 9,994,851, 10,227,590, and 10,266,827, collectively the “UWA Patents”). In its complaint, NS sought legal fees and costs, an unspecified amount of monetary relief (treble damages) attributed to Sarepta’s alleged infringement, and such other relief as the court deems just and proper. In January 2022, the PTAB granted institution of all claims of all NS Patents in response to Sarepta’s IPR Petitions and determined that Sarepta demonstrated a reasonable likelihood of success in proving that the NS Patents are unpatentable. NS filed a motion for preliminary injunction solely seeking Sarepta’s withdrawal of the IPR Petitions, which was ultimately granted after the U.S. Court of Appeals for the Federal Circuit reversed and remanded to the district court on February 8, 2022. Sarepta subsequently withdrew the IPRs, which were terminated on June 14, 2022. On December 27, 2021, the district court partially granted and denied the motion to dismiss by Sarepta and ordered NS to file a Second Amended Complaint (“SAC”), which it did on January 14, 2022. In the SAC, NS maintained all claims of the original complaint of July 13, 2021, except a determination of non-infringement of the UWA Patents. On January 28, 2022, Sarepta filed its answer to the SAC, with defenses and counterclaims against NS and NS Pharma Inc. that include infringement of the UWA Patents allegedly arising from their activities concerning, including the sale of, its exon 53 skipping product, Viltepso (viltolarsen) and breach of contract. Sarepta also sought a determination of invalidity of the NS Patents. In its counterclaim complaint, Sarepta sought an award of relief in its defenses to NS’ allegations, a judgment of breach of contract, a determination of invalidity of the NS Patents, a judgment of infringement and willful infringement of the UWA Patents, legal fees and costs, an unspecified amount of monetary relief (treble damages) attributable to NS’ alleged infringement, and such other relief as the court deems just and proper. UWA has since been joined as a Plaintiff in Sarepta’s counterclaims against NS. On August 14, 2023, the Court granted cross motions to amend the pleadings, allowing Sarepta to add a counterclaim against NS for inequitable conduct, and NS to add counterclaims against Sarepta for inequitable conduct and Walker Process fraud. The parties have since stipulated to the dismissal of NS's claim of infringement of its ’361 Patent and certain claims of the ’322 Patent, and NS’s breach of contract claim. The Court bifurcated the Walker Process fraud claim on April 18, 2024, and granted Sarepta's motion for summary judgement of infringement of the '851 Patent and NS’s motion for partial summary judgment of infringement of certain NS patents on May 1, 2024. A trial is scheduled to commence on December 16, 2024. On or about June 5, 2023, Sarepta initiated a patent infringement lawsuit against Nippon Shinyaku in Japan, alleging that NS’s production, sales and offers to sell Viltepso infringe Sarepta’s Japanese Patent No. 6406782. NS filed its preliminary answer on July 13, 2023. A technical presentation session occurred on July 26, 2024. On July 26, 2024, Genzyme Corporation filed a lawsuit against Sarepta Therapeutics, Inc. and Sarepta Therapeutics Three, LLC, in the U.S. District Court for the District of Delaware. The complaint asserts infringement of United States Patent Nos. 9,051,542 (the “’542 Patent”) and 7,704,721 (the “’721 Patent”) arising from Sarepta’s alleged manufacture and sale of ELEVIDYS® (delandistrogene moxeparvovec-rokl). In its complaint, Genzyme seeks, inter alia, damages for the alleged infringement, including increased damages up to three times the amount found or assessed, together with prejudgment and post-judgment interest and costs.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2024
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	16. SUBSEQUENT EVENTS The Company issued a termination notice to Brammer Bio MA, LLC, an affiliate of Thermo Fisher Scientific, Inc. (“Thermo” ) on July 18, 2024 to terminate the development, commercial manufacturing, and supply agreement, as related to the Company's adherent manufacturing process for its gene therapy programs. The termination will be effective as of August 21, 2024 and the Company is currently performing its analysis of the financial impact of the termination. As of the date of this report, the Company expects to record between approximately $ 55.0 million to $ 65.0 million in additional expense as a result of this termination for the three and nine months ended September 30, 2024 . This range is the net impact of any expected termination expenses and write-offs and the reduction to operating expense for applicable reimbursable costs under the Roche Agreement. As the Company had yet to obtain regulatory approval to produce commercial supply of ELEVIDYS at Thermo manufacturing facilities prior to the issuance of this termination notice, the Company will record these amounts as research and development expenses in the three and nine months ended September 30, 2024. The Company is analyzing any further impact from the termination that will be recorded for the three and nine months ended September 30, 2024. For more information related to Thermo, please read Note 21, Commitments and Contingencies to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2024
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 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 consolidated financial statements and related notes for the year ended December 31, 2023 which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed with the U.S. Securities and Exchange Commission on February 28, 2024. The results for the three and six months ended June 30, 2024 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, revenues, 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 cash held at financial institutions, cash equivalents, investments and accounts receivable, net, from customers. As of June 30, 2024, the Company’s cash was concentrated at three financial institutions, 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. The Company also purchases commercial paper, government and government agency bonds, corporate bonds and certificates of deposit issued by highly rated corporations, financial institutions and governments and limits the amount of credit exposure to any one issuer. These amounts may at times exceed federally insured limits. The Company has not experienced any credit losses related to these financial instruments and does not believe to be exposed to any significant credit risk related to these instruments. As of June 30, 2024 , three entities accounted for 33 % , 28 % and 15 % of accounts receivable, net, respectively. As of December 31, 2023, four entities accounted for 40 % , 19 % , 19 % and 12 % of accounts receivable, net, respectively. As of June 30, 2024 , the Company believes its largest customers are of high credit quality and has not experienced any material credit losses related to such customers.
Significant Accounting Policies	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, 2023. There have not been any material changes to the Company's accounting policies or recent accounting pronouncements that could have a material impact through June 30, 2024 .

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured and Carried at Fair Value	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 the valuation techniques it utilizes to determine such fair value: Fair Value Measurement as of June 30, 2024 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 100,859 $ 100,859 $ — $ — Commercial paper 26,866 — 26,866 — Government and government agency bonds 854,254 — 854,254 — Corporate bonds 180,781 — 180,781 — Strategic investments 7,606 6,606 — 1,000 Certificates of deposit 53,130 — 53,130 — Total assets $ 1,223,496 $ 107,465 $ 1,115,031 $ 1,000 Liabilities Contingent consideration $ 48,200 $ — $ — $ 48,200 Total liabilities $ 48,200 $ — $ — $ 48,200 Fair Value Measurement as of December 31, 2023 Total Level 1 Level 2 Level 3 (in thousands) Assets Money market funds $ 63,919 $ 63,919 $ — $ — Commercial paper 113,362 — 113,362 — Government and government agency bonds 1,001,137 — 1,001,137 — Corporate bonds 130,380 — 130,380 — Strategic investments 6,527 5,527 — 1,000 Certificates of deposit 56,621 — 56,621 — Total assets $ 1,371,946 $ 69,446 $ 1,301,500 $ 1,000 Liabilities Contingent consideration $ 38,100 $ — $ — $ 38,100 Total liabilities $ 38,100 $ — $ — $ 38,100
Summary of Fair Value of Level 3 Financial Liabilities	The following table represents a roll-forward of the fair value of Level 3 financial liabilities for the periods indicated: As of As of (in thousands) Fair value, as of beginning of period $ 38,100 $ 36,900 Change in estimated fair value 10,100 — Liabilities terminated — ( 800 ) Fair value, as of end of period $ 48,200 $ 36,100

CASH, CASH EQUIVALENTS AND MA_2

CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (Tables)	6 Months Ended
	Jun. 30, 2024
Cash and Cash Equivalents [Abstract]
Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents	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 As of (in thousands) Money market funds $ 100,859 $ 63,919 Government and government agency bonds 29,058 — Corporate bonds 9,121 — Commercial paper — 53,680 Total $ 139,038 $ 117,599
Summary of Company Cash, Cash Equivalents and Short-Term Investments	The following tables summarize the Company ’s cash, cash equivalents and short-term investments for each of the periods indicated: As of June 30, 2024 Amortized Gross Gross Fair (in thousands) Cash and money market funds $ 345,443 $ — $ — $ 345,443 Commercial paper 26,866 — — 26,866 Government and government agency bonds 855,148 — ( 894 ) 854,254 Corporate bonds 180,890 6 ( 115 ) 180,781 Certificates of deposit 53,130 — — 53,130 Total cash, cash equivalents and investments $ 1,461,477 $ 6 $ ( 1,009 ) $ 1,460,474 As reported: Cash and cash equivalents $ 383,623 $ — $ ( 1 ) $ 383,622 Short-term investments 1,077,854 6 ( 1,008 ) 1,076,852 Total cash, cash equivalents and investments $ 1,461,477 $ 6 $ ( 1,009 ) $ 1,460,474 As of December 31, 2023 Amortized Gross Gross Fair (in thousands) Cash and money market funds $ 374,750 $ — $ — $ 374,750 Commercial paper 113,362 — — 113,362 Government and government agency bonds 1,000,302 1,006 ( 171 ) 1,001,137 Corporate bonds 130,270 118 ( 8 ) 130,380 Certificates of deposit 56,621 — — 56,621 Total cash, cash equivalents and investments $ 1,675,305 $ 1,124 $ ( 179 ) $ 1,676,250 As reported: Cash and cash equivalents $ 428,430 $ — $ — $ 428,430 Short-term investments 1,246,875 1,124 ( 179 ) 1,247,820 Total cash, cash equivalents and investments $ 1,675,305 $ 1,124 $ ( 179 ) $ 1,676,250

PRODUCT REVENUES, NET, ACCOUN_2

PRODUCT REVENUES, NET, ACCOUNTS RECEIVABLE, NET, AND RESERVES FOR PRODUCT REVENUES (Tables)	6 Months Ended
	Jun. 30, 2024
Receivables, Net, Current [Abstract]
Summary of Product Revenues	Net product revenues, which includes revenues associated with the PMO Products and ELEVIDYS, consisted of the following: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) PMO Products United States $ 204,248 $ 203,895 $ 393,915 $ 404,346 Rest of World 34,579 35,093 70,460 66,137 Total PMO product revenues, net $ 238,827 $ 238,988 $ 464,375 $ 470,483 ELEVIDYS United States 121,721 — 255,657 — Total ELEVIDYS product revenue, net $ 121,721 $ — $ 255,657 $ — Total product revenues, net $ 360,548 $ 238,988 $ 720,032 $ 470,483
Schedule of Product revenue Concentration risks	The following table summarizes the Company's net product revenues, by customer, for those customers that exceeded 10 % for the periods indicated: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 Product revenues, net Customer 1 35 % 47 % 35 % 48 % Customer 2 21 % 33 % 20 % 32 %
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, 2023 $ 27,486 $ 98,194 $ 3,831 $ 35,261 $ 164,772 Provision 41,935 72,684 8,585 35,527 158,731 Adjustments relating to prior periods 783 ( 5,171 ) — ( 88 ) ( 4,476 ) Payments/credits ( 54,393 ) ( 62,647 ) ( 8,462 ) ( 33,210 ) ( 158,712 ) Balance, as of June 30, 2024 $ 15,811 $ 103,060 $ 3,954 $ 37,490 $ 160,315 Chargebacks Rebates Prompt Pay Other Accruals Total (in thousands) Balance, as of December 31, 2022 $ 417 $ 67,493 $ 3,343 $ 23,445 $ 94,698 Provision 6,287 60,824 7,228 32,220 106,559 Adjustments relating to prior periods — ( 3,437 ) — — ( 3,437 ) Payments/credits ( 6,434 ) ( 45,592 ) ( 6,976 ) ( 24,820 ) ( 83,822 ) Balance, as of June 30, 2023 $ 270 $ 79,288 $ 3,595 $ 30,845 $ 113,998
Summary of Total Reserves Included in Consolidated Balance Sheets	The following table summarizes the total reserves above included in the Company’s unaudited condensed consolidated balance sheets for each of the periods indicated: As of As of (in thousands) Reduction to accounts receivable $ 55,663 $ 64,697 Component of accrued expenses 104,652 100,075 Total reserves $ 160,315 $ 164,772

INVENTORY (Tables)

INVENTORY (Tables)	6 Months Ended
	Jun. 30, 2024
Inventory Disclosure [Abstract]
Schedule of Components of Inventory	The following table summarizes the components of the Company’s inventory for each of the periods indicated: As of As of (in thousands) Raw materials $ 167,201 $ 133,963 Work in progress 470,381 318,458 Finished goods 52,904 61,806 Total inventory $ 690,486 $ 514,227
Summary of Inventory Balance Sheet Classification	The following table summarizes the balance sheet classification of the Company's inventory for each of the periods indicated: As of As of (in thousands) Balance sheet classification Inventory $ 485,795 $ 322,859 Non-current inventory 204,691 191,368 Total inventory $ 690,486 $ 514,227

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	6 Months Ended
	Jun. 30, 2024
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 As of (in thousands) Collaboration and other receivables $ 19,869 $ 29,786 Prepaid maintenance services 14,266 11,281 Prepaid clinical and pre-clinical expenses 12,356 10,280 Tax-related receivables and prepaids 8,415 6,862 Interest receivable 3,979 2,731 Prepaid insurance 3,932 3,352 Prepaid commercial expenses 3,684 2,729 Other 8,242 10,693 Total other current assets $ 74,743 $ 77,714
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 As of (in thousands) Manufacturing-related deposits and prepaids $ 77,102 $ 74,204 Intangible assets, net 28,252 29,620 Restricted cash* 15,579 15,579 Strategic investments 7,606 6,527 Prepaid maintenance services 4,046 5,466 Other 3,144 5,375 Total other non-current assets $ 135,729 $ 136,771 * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	6 Months Ended
	Jun. 30, 2024
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 As of (in thousands) Product revenue related reserves $ 104,652 $ 100,075 Accrued contract manufacturing costs 77,451 33,024 Accrued employee compensation costs 50,023 78,732 Accrued clinical and pre-clinical costs 36,221 34,669 Accrued professional fees 22,885 17,187 Accrued fixed assets 21,163 3,231 Accrued income taxes 18,186 13,766 Accrued royalties 7,724 12,070 Accrued interest 4,368 4,395 Accrued research expenses 2,737 2,441 Other 4,994 4,032 Total accrued expenses $ 350,404 $ 314,997

INDEBTEDNESS (Tables)

INDEBTEDNESS (Tables)	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Summary of Debt Facilities	The following table summarizes the Company’s debt facilities for each of the periods indicated: As of As of (in thousands) Principal amount of the 2024 Notes $ 91,641 $ 105,847 Principal amount of the 2027 Notes 1,150,000 1,150,000 Unamortized discount - debt issuance costs of 2024 Notes ( 136 ) ( 364 ) Unamortized discount - debt issuance costs of 2027 Notes ( 15,190 ) ( 17,485 ) Total carrying value of debt facilities $ 1,226,315 $ 1,237,998 Fair value of 2024 Notes $ 206,338 $ 144,833 Fair value of 2027 Notes 1,485,409 1,172,276 Total fair value of debt facilities $ 1,691,747 $ 1,317,109
Summarizes Total Gross Payments Due under Company's Debt Arrangements	The following table summarizes the total principal and contractual interest payments due under the Company’s debt arrangements: As of June 30, 2024 Principal Interest Total Payments (in thousands) 2024 (July-December) $ 91,641 $ 7,898 $ 99,539 2025 — 14,375 14,375 2026 — 14,375 14,375 2027 1,150,000 14,375 1,164,375 Total payments $ 1,241,641 $ 51,023 $ 1,292,664

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [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 June 30, For the Six Months Ended June 30, 2024 2023 2024 2023 Grants Weighted Grants Weighted Grants Weighted Grants Weighted Stock options 5,100 $ 72.37 54,575 $ 66.82 321,478 $ 67.63 1,084,924 $ 72.50 Restricted stock units 54,905 (1) $ 138.91 33,752 $ 121.27 1,216,890 (1) $ 129.05 1,109,663 (2) $ 153.89 (1) Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2024 are 8,860 and 97,460 shares with performance conditions (“March 2024 PSUs”), respectively, which are related to the achievement of certain financial performance goals and regulatory approval of certain of the Company's product candidates. The expanded regulatory approval of ELEVIDYS in June 2024 resulted in the cliff-vesting of 44,300 of the 97,460 shares of the March 2024 PSUs during the three and six months ended June 30, 2024. As of June 30, 2024 , none of the performance conditions for the remaining 53,160 shares were probable of being achieved. Stock options and the remaining RSUs granted during the three and six months ended June 30, 2024 have only service-based criteria and vest over four years. (2) Included in the RSUs for the six months ended June 30, 2023 are 502,225 shares with performance conditions (the “March 2023 PSUs”), which are related to regulatory approval of ELEVIDYS and achievement of a certain financial performance target, both of which were achieved in 2023. Vesting of the March 2023 PSUs is contingent on the fulfillment of remaining service conditions.
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 and by function included within the unaudited condensed consolidated statements of comprehensive income (loss): For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) Stock options $ 15,515 $ 21,135 $ 31,796 $ 44,965 Restricted stock units 37,808 25,037 65,335 41,177 Employee stock purchase plan 2,331 1,205 3,728 2,485 Subtotal $ 55,654 $ 47,377 $ 100,859 $ 88,627 Capitalized stock-based compensation costs* ( 5,172 ) — ( 9,685 ) — Total stock-based compensation expense included in expenses $ 50,482 $ 47,377 $ 91,174 $ 88,627 Research and development 19,806 21,577 36,079 37,990 Selling, general and administrative 30,676 25,800 55,095 50,637 Total stock-based compensation expense included in expenses $ 50,482 $ 47,377 $ 91,174 $ 88,627 * Prior to the six months ended June 30, 2024 , capitalized stock-based compensation costs were not material.

OTHER INCOME (LOSS), NET (Table

OTHER INCOME (LOSS), NET (Tables)	6 Months Ended
	Jun. 30, 2024
Other Income and Expenses [Abstract]
Summary of Other Income (Loss)	The following table summarizes other income (loss), net f or each of the periods indicated: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands) Accretion of investment discount, net $ 10,766 $ 12,786 $ 23,570 $ 22,825 Interest income 8,076 8,418 15,169 17,694 Interest expense ( 4,832 ) ( 5,224 ) ( 8,998 ) ( 11,547 ) Change in the fair value of contingent consideration — 800 ( 10,100 ) 800 Other, net 268 154 1,180 ( 131 ) Other income, net $ 14,278 $ 16,934 $ 20,821 $ 29,641 Gain from sale of Priority Review Voucher — 102,000 — 102,000 Loss on debt extinguishment — — — ( 387,329 ) Total other income (loss), net $ 14,278 $ 118,934 $ 20,821 $ ( 255,688 )

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	The following table sets forth the computation of basic and diluted earnings (loss) per common share: For the Three Months Ended For the Six Months Ended 2024 2023 2024 2023 (in thousands, except per share amounts) Numerator: Net income (loss) - basic $ 6,460 $ ( 23,940 ) $ 42,579 $ ( 540,695 ) Add: interest expense, net of tax, on the Company's convertible debt 340 — 769 — Net income (loss) - diluted $ 6,800 $ ( 23,940 ) $ 43,348 $ ( 540,695 ) Denominator: Weighted-average common shares outstanding, basic 94,618 88,743 94,305 88,466 Effect of dilutive securities: Common stock issuable under the Company's equity incentive plans 3,095 — 3,388 — Common stock issuable under the Company's convertible debt 1,431 — 1,436 — Weighted-average common shares outstanding, diluted 99,144 88,743 99,129 88,466 Earnings (loss) per common share, basic $ 0.07 $ ( 0.27 ) $ 0.45 $ ( 6.11 ) Earnings (loss) per common share, diluted $ 0.07 $ ( 0.27 ) $ 0.44 $ ( 6.11 )
Summary of Potential Shares of Common Stock that were Excluded from the Computation of Diluted Earnings per Share	The following table summarizes potential shares of common stock that were excluded from the computation of diluted earnings per share as they were anti-dilutive: As of As of (in thousands) Common stock issuable under the Company's equity incentive plans 2,879 (1) 12,316 (2) Common stock issuable under the Company's convertible debt 8,100 9,542 Total number of potentially issuable common stock 10,979 21,858 (1) As of June 30, 2024, the anti-dilutive common stock issuable under the Company's equity incentive plans excludes 1.2 million shares that are dilutive but have performance or market conditions that were not met as of the end of the period. (2) As of June 30, 2023, the anti-dilutive common stock issuable under the Company's equity incentive plans includes 1.2 million shares that have performance or market conditions that were not met as of the end of the period because these were anti-dilutive as the Company was in a net loss position at the end of the period .

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	6 Months Ended
	Jun. 30, 2024
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 (in thousands) 2024 (July-December) $ 757,166 2025 230,756 2026 108,260 2027 77,630 2028 72,343 Total manufacturing commitments* $ 1,246,155 * Total manufacturing commitments include the Catalent, Inc. (“Catalent”) manufacturing and supply agreement, for which the Company has ROU assets and lease liabilities recorded on the unaudited condensed consolidated balance sheets as of June 30, 2024 .

Organization and Nature of Bu_2

Organization and Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2024		Dec. 31, 2023		Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash cash equivalents restricted cash and investments	$ 1,476,100
Cash and cash equivalents	383,622		$ 428,430		$ 851,929
Short-term investments	1,076,852		1,247,820
Restricted cash non current	$ 15,579	[1]	$ 15,579	[1]	$ 19,024
[1] * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2024 USD ($) $ / shares	Mar. 31, 2024 USD ($)	Jun. 30, 2023 USD ($) $ / shares	Mar. 31, 2023 USD ($)	Jun. 30, 2024 USD ($) Segment $ / shares	Jun. 30, 2023 USD ($) $ / shares	Dec. 31, 2023
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segment					1
Interest expense reduced	$ 5,200		$ 5,200		$ 10,500	$ 11,500
Net Income (Loss)	$ 6,460	$ 36,119	$ (23,940)	$ (516,755)	$ 42,579	$ (540,695)
Earnings (loss) per common share, diluted | $ / shares	$ 0.07		$ (0.27)		$ 0.44	$ (6.11)
Customer One [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage					33%		40%
Customer Two [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage					28%		19%
Customer Three [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage					15%		19%
Customer Four [Member] | Customer Concentration Risk [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage							12%

License and Collaboration Agr_2

License and Collaboration Agreements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net	$ 360,548	$ 238,988	$ 720,032	$ 470,483
Collaboration receivable	19,869		19,869		$ 29,786
Development Milestone and Upfront Fee Recognized as Research and Development Expense	0	7,600	0	8,100
ELEVIDYS [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net	121,721	0	255,657	0
Collaborative Arrangement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for option exercise			121,800
Research, option and milestone expense	0		0
Collaborative Arrangement | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent research milestone payments			34,800
Development Milestone and Upfront Fee Recognized as Research and Development Expense			2,800,000
Collaborative Arrangement | Research and Development Expense
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front and development milestone expenses		7,500		7,500
Collaborative Arrangement | Roche Holding A.G. [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product revenues, net		22,300	48,000	44,300
Deferred Revenue	447,000		447,000		487,400
Deferred Revenue, Current	122,000		122,000		50,400
Research and development expense	17,900	28,200	39,600	48,500
Collaboration Receivable	19,900		19,900		$ 29,800
Collaborative Arrangement | Roche Holding A.G. [Member] | ELEVIDYS [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Inventory Cost			1,700
Collaboration receivable	5,800	0	5,800	0
Royalty revenue	$ 2,400	$ 0	$ 2,600	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured and Carried at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 1,223,496	$ 1,371,946
Contingent consideration	48,200	38,100
Total liabilities	48,200	38,100
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	100,859	63,919
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,866	113,362
Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	854,254	1,001,137
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	180,781	130,380
Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	7,606	6,527
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	53,130	56,621
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	107,465	69,446
Contingent consideration	0	0
Total liabilities	0	0
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	100,859	63,919
Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 [Member] | Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 [Member] | Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	6,606	5,527
Level 1 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,115,031	1,301,500
Contingent consideration	0	0
Total liabilities	0	0
Level 2 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	26,866	113,362
Level 2 [Member] | Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	854,254	1,001,137
Level 2 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	180,781	130,380
Level 2 [Member] | Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	53,130	56,621
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,000	1,000
Contingent consideration	48,200	38,100
Total liabilities	48,200	38,100	$ 36,100	$ 36,900
Level 3 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 [Member] | Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 [Member] | Strategic Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,000	1,000
Level 3 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value of Level 3 Financial Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value at the beginning of the period			$ 38,100
Change in the fair value of contingent consideration	$ 0	$ (800)	10,100	$ (800)
Fair value at the end of the period	48,200		48,200
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value at the beginning of the period			38,100	36,900
Change in the fair value of contingent consideration			10,100	0
Liabilities Terminated			0	(800)
Fair value at the end of the period	$ 48,200	$ 36,100	$ 48,200	$ 36,100

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of contingent consideration liability	$ 0	$ (800)	$ 10,100	$ (800)

Cash, Cash Equivalents and Ma_3

Cash, Cash Equivalents and Marketable Securities - Summary of Company Financial Assets with Maturities of Less Than 90 Days Included in Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 139,038	$ 117,599
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	100,859	63,919
Corporate Bond [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	9,121	0
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	29,058	0
Commercial Paper [Member]
Cash and Cash Equivalents [Line Items]
Cash equivalents	$ 0	$ 53,680

Cash, Cash Equivalents and Ma_4

Cash, Cash Equivalents and Marketable Securities - Summary of Company Cash, Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Amortized cost	$ 1,077,854	$ 1,246,875
Available for sale debt securities, Gross unrealized gains	6	1,124
Available for sale debt securities, Gross unrealized losses	(1,008)	(179)
Cash and cash equivalents, Amortized cost	1,461,477	1,675,305
Cash and cash equivalents, Gross unrealized losses	(1)
Cash and cash equivalents	383,622	428,430	$ 851,929
Cash, cash equivalents and investments, Amortized cost	383,623	428,430
Cash, cash equivalents and investments, Gross unrealized gains	6	1,124
Cash, cash equivalents and investments, Gross unrealized losses	(1,009)	(179)
Cash, cash equivalents and investments, Fair value	1,460,474	1,676,250
Available for sale debt securities current, Fair value	1,076,852	1,247,820
Cash and Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents, Amortized cost	345,443	374,750
Cash and cash equivalents	345,443	374,750
Commercial Paper [Member]
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Fair value	26,866	113,362
Cash and cash equivalents, Amortized cost	26,866	113,362
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Gross unrealized gains		1,006
Available for sale debt securities, Gross unrealized losses	(894)	(171)
Available for sale debt securities, Fair value	854,254	1,001,137
Cash and cash equivalents, Amortized cost	855,148	1,000,302
Corporate Bond [Member]
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Gross unrealized gains	6	118
Available for sale debt securities, Gross unrealized losses	(115)	(8)
Available for sale debt securities, Fair value	180,781	130,380
Cash and cash equivalents, Amortized cost	180,890	130,270
Certificates of Deposit [Member]
Cash and Cash Equivalents [Line Items]
Available for sale debt securities, Fair value	53,130	56,621
Cash and cash equivalents, Amortized cost	$ 53,130	$ 56,621

Cash, Cash Equivalents and Ma_5

Cash, Cash Equivalents and Marketable Securities - Additional Information (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Line Items]
Weighted average maturity period of available-for-sale securities	5 months	5 months

Product Revenues, Net, Accoun_3

Product Revenues, Net, Accounts Receivable, Net, and Reserves for Product Revenues - Summary of Product Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Product Information [Line Items]
Products, net	$ 360,548	$ 238,988	$ 720,032	$ 470,483
PMO Products [Member]
Product Information [Line Items]
Products, net	238,827	238,988	464,375	470,483
PMO Products [Member] | United States [Member]
Product Information [Line Items]
Products, net	204,248	203,895	393,915	404,346
PMO Products [Member] | Rest of World [Member]
Product Information [Line Items]
Products, net	34,579	35,093	70,460	66,137
ELEVIDYS [Member]
Product Information [Line Items]
Products, net	121,721	0	255,657	0
ELEVIDYS [Member] | United States [Member]
Product Information [Line Items]
Products, net	$ 121,721	$ 0	$ 255,657	$ 0

Product Revenues, Net, Accoun_4

Product Revenues, Net, Accounts Receivable, Net, and Reserves for Product Revenues (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Products, net	$ 360,548	$ 238,988	$ 720,032	$ 470,483
Revenues	362,931	$ 261,238	776,395	$ 514,738
Product sales receivable, net of discounts and allowances	$ 360,000		$ 360,000		$ 400,300
Payment Terms			As of June 30, 2024, 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 65 to 90 days. Outside of the U.S., the majority of the Company’s customers have payment terms ranging between 90 and 150 days.
Sales Revenue Net [Member] | Customer Concentration Risk [Member] | Customer One [Member]
Concentration of credit risk percentage	35%	47%	35%	48%
Sales Revenue Net [Member] | Customer Concentration Risk [Member] | Customer Two [Member]
Concentration of credit risk percentage	21%	33%	20%	32%
Sales Revenue Net [Member] | Customer Concentration Risk [Member] | No Individual [Member]
Concentration of credit risk percentage			10%	10%
Sales Revenue Net [Member] | Customer Concentration Risk [Member] | Customers Exceed [Member]
Concentration of credit risk percentage			10%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer One [Member]
Concentration of credit risk percentage			33%		40%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer Two [Member]
Concentration of credit risk percentage			28%		19%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer Three [Member]
Concentration of credit risk percentage			15%		19%

Product Revenues, Net, Accoun_5

Product Revenues, Net, Accounts Receivable, Net, and Reserves for Product Revenues - Summarizes the concentration of the three largest customers (Details) - Customer Concentration Risk [Member] - Revenue Benchmark [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Customer One [Member]
Principal Transaction Revenue [Line Items]
Concentration Risk, Percentage	35%	47%	35%	48%
Customer Two [Member]
Principal Transaction Revenue [Line Items]
Concentration Risk, Percentage	21%	33%	20%	32%

Product Revenues, Net, Accoun_6

Product Revenues, Net, Accounts Receivable, Net, and Reserves for Product Revenues - Summary of Change in Reserves for Discounts and Allowances (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	$ 164,772	$ 94,698
Provision	158,731	106,559
Adjustments relating to prior periods	(4,476)	(3,437)
Payments/credits	(158,712)	(83,822)
Ending balance	160,315	113,998
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	27,486	417
Provision	41,935	6,287
Adjustments relating to prior periods	783	0
Payments/credits	(54,393)	(6,434)
Ending balance	15,811	270
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	98,194	67,493
Provision	72,684	60,824
Adjustments relating to prior periods	(5,171)	(3,437)
Payments/credits	(62,647)	(45,592)
Ending balance	103,060	79,288
Prompt Pay [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	3,831	3,343
Provision	8,585	7,228
Adjustments relating to prior periods	0	0
Payments/credits	(8,462)	(6,976)
Ending balance	3,954	3,595
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance	35,261	23,445
Provision	35,527	32,220
Adjustments relating to prior periods	(88)	0
Payments/credits	(33,210)	(24,820)
Ending balance	$ 37,490	$ 30,845

Product Revenues, Net, Accoun_7

Product Revenues, Net, Accounts Receivable, Net, and Reserves for Product Revenues - Summary of Total Reserves Included in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Receivables, Net, Current [Abstract]
Reduction to accounts receivable	$ 55,663	$ 64,697
Component of accrued expenses	104,652	100,075
Total reserves	$ 160,315	$ 164,772	$ 113,998	$ 94,698

Inventory - Summary of Componen

Inventory - Summary of Components of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Raw materials	$ 167,201	$ 133,963
Work in progress	470,381	318,458
Finished goods	52,904	61,806
Total inventory	$ 690,486	$ 514,227

Inventory - Summarizes the Bala

Inventory - Summarizes the Balance Sheet Classification (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Inventory	$ 485,795	$ 322,859
Non-current inventory	204,691	191,368
Total inventory	$ 690,486	$ 514,227

OTHER ASSETS (Additional Inform

OTHER ASSETS (Additional Information) (Details) - USD ($) $ in Thousands	Jun. 30, 2024		Dec. 31, 2023		Jun. 30, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Restricted cash in other assets	$ 15,579	[1]	$ 15,579	[1]	$ 19,024
[1] * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

Other Assets - Summary of Other

Other Assets - Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Collaboration and other receivables	$ 19,869	$ 29,786
Prepaid maintenance services	14,266	11,281
Prepaid clinical and pre-clinical expenses	12,356	10,280
Tax-related receivables and prepaids	8,415	6,862
Interest receivable	3,979	2,731
Prepaid insurance	3,932	3,352
Prepaid commercial expenses	3,684	2,729
Other	8,242	10,693
Total other current assets	$ 74,743	$ 77,714

Other Assets - Summary of Oth_2

Other Assets - Summary of Other Non-current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2024		Dec. 31, 2023		Jun. 30, 2023
Prepaid Expense and Other Assets, Noncurrent [Abstract]
Manufacturing-related deposits and prepaids	$ 77,102		$ 74,204
Intangible assets, net	28,252		29,620
Restricted cash non current	15,579	[1]	15,579	[1]	$ 19,024
Strategic investments	7,606		6,527
Prepaid maintenance services	4,046		5,466
Other	3,144		5,375
Total other non-current assets	$ 135,729		$ 136,771
[1] * The Company had approximatel y $ 15.6 million in restricted cash included in other non-current assets on the Company’s unaudited condensed consolidated balance sheets as of both June 30, 2024 and December 31, 2023 . Restricted cash for both periods relates to (i) letters of credit established under the Company’s various property leases that serve as security for potential future default of lease payments, (ii) a letter of credit established under a certain commercial supply agreement and (iii) collateralized cash for the Company’s credit cards. The restricted cash is unavailable for withdrawal or use for general obligations.

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Product revenue related reserves	$ 104,652	$ 100,075
Accrued contract manufacturing costs	77,451	33,024
Accrued employee compensation costs	50,023	78,732
Accrued clinical and pre-clinical costs	36,221	34,669
Accrued professional fees	22,885	17,187
Accrued fixed assets	21,163	3,231
Accrued income taxes	18,186	13,766
Accrued royalties	7,724	12,070
Accrued interest	4,368	4,395
Accrued research expenses	2,737	2,441
Other	4,994	4,032
Total accrued expenses	$ 350,404	$ 314,997

Indebtedness - Additional Infor

Indebtedness - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions				3 Months Ended			6 Months Ended
	Mar. 02, 2023	Sep. 14, 2022	Nov. 14, 2017	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Debt Instrument [Line Items]
Debt instrument, face amount				$ 1,292,664			$ 1,292,664
Partial settlement of capped call share options for 2024 Notes						$ 80,645	0	$ 80,645
Loss on debt extinguishment				0	$ 0		0	(387,329)
Debt conversion costs for 2024 Notes							0	6,887
Interest expense debt				5,200	5,200		10,500	11,500
Long-term debt				1,134,810			1,134,810		$ 1,132,515
Aggregate long-term debt				1,226,315			1,226,315		1,237,998
Amortization of Debt Issuance Costs				1,300	$ 1,200		2,500	$ 2,700
Convertible Debt, The Term Loan, The Revolver and The Mortgage Loans [Member]
Debt Instrument [Line Items]
Long-term debt				1,226,300			1,226,300		1,238,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 570,000	$ 91,641			$ 91,641		105,847
Issuance of common stock for exchange of 2024 Notes, shares	4.5			0.2			0.2
Aggregate principal amount converted into equity				$ 14,200			$ 14,200
Debt instrument, maturity date			Nov. 15, 2024
2024 Convertible Notes [Member] | Common Stock [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 313,500
2027 Convertible Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 1,150,000			$ 1,150,000		$ 1,150,000
2017 Capped Calls Partial Settlement [Member]
Debt Instrument [Line Items]
Partial settlement of capped call share options for 2024 Notes	$ 80,600	$ 26,300
2024 Notes Repurchase [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		150,600
Payment for full settlement of the principal value and accrued interest		$ 248,600

Indebtedness - Summary of Debt

Indebtedness - Summary of Debt Facilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Nov. 14, 2017
Debt Instrument [Line Items]
Principal amount	$ 1,292,664
Total carrying value of debt facilities	1,226,315	$ 1,237,998
Total fair value of debt facilities	1,691,747	1,317,109
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount	91,641	105,847	$ 570,000
Unamortized discount - debt issuance costs	(136)	(364)
Total fair value of debt facilities	206,338	144,833
2027 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount	1,150,000	1,150,000
Unamortized discount - debt issuance costs	(15,190)	(17,485)
Total fair value of debt facilities	$ 1,485,409	$ 1,172,276

Indebtedness - Summarizes Total

Indebtedness - Summarizes Total Gross Payments Due under Company's Debt Arrangements (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
Debt Instrument [Line Items]
2024 (July-December)	$ 99,539
2025	14,375
2026	14,375
2027	1,164,375
Total payments	1,292,664
Principal [Member]
Debt Instrument [Line Items]
2024 (July-December)	91,641
2025	0
2026	0
2027	1,150,000
Total payments	1,241,641
Interest [Member]
Debt Instrument [Line Items]
2024 (July-December)	7,898
2025	14,375
2026	14,375
2027	14,375
Total payments	$ 51,023

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Awards Granted (Detail) - $ / shares	3 Months Ended			6 Months Ended				12 Months Ended
	Jun. 30, 2024		Jun. 30, 2023	Jun. 30, 2024		Jun. 30, 2023		Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	5,100		54,575	321,478		1,084,924
Weighted Average Grant Date Fair Value, Stock options	$ 72.37		$ 66.82	$ 67.63		$ 72.5
Grants, Restricted stock units	54,905	[1]	33,752	1,216,890	[1]	1,109,663	[2]
Weighted Average Grant Date Fair Value, Restricted stock units	$ 138.91		$ 121.27	$ 129.05		$ 153.89
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	8,860			97,460		502,225		38,500
[1] Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2024 are 8,860 and 97,460 shares with performance conditions (“March 2024 PSUs”), respectively, which are related to the achievement of certain financial performance goals and regulatory approval of certain of the Company's product candidates. The expanded regulatory approval of ELEVIDYS in June 2024 resulted in the cliff-vesting of 44,300 of the 97,460 shares of the March 2024 PSUs during the three and six months ended June 30, 2024. As of June 30, 2024 , none of the performance conditions for the remaining 53,160 shares were probable of being achieved. Stock options and the remaining RSUs granted during the three and six months ended June 30, 2024 have only service-based criteria and vest over four years. Included in the RSUs for the six months ended June 30, 2023 are 502,225 shares with performance conditions (the “March 2023 PSUs”), which are related to regulatory approval of ELEVIDYS and achievement of a certain financial performance target, both of which were achieved in 2023. Vesting of the March 2023 PSUs is contingent on the fulfillment of remaining service conditions.

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Awards Granted (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended				12 Months Ended
	Jun. 30, 2024		Jun. 30, 2023	Jun. 30, 2024		Jun. 30, 2023		Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	5,100		54,575	321,478		1,084,924
Expanded Grants, Stock options	54,905	[1]	33,752	1,216,890	[1]	1,109,663	[2]
Stock-based compensation expense	$ 50.5		$ 47.4	$ 91.2		$ 88.6
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants, Stock options	8,860			97,460		502,225		38,500
Remaining shares associated with performance condition				53,160
Vesting PSUs	44,300			97,460
[1] Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2024 are 8,860 and 97,460 shares with performance conditions (“March 2024 PSUs”), respectively, which are related to the achievement of certain financial performance goals and regulatory approval of certain of the Company's product candidates. The expanded regulatory approval of ELEVIDYS in June 2024 resulted in the cliff-vesting of 44,300 of the 97,460 shares of the March 2024 PSUs during the three and six months ended June 30, 2024. As of June 30, 2024 , none of the performance conditions for the remaining 53,160 shares were probable of being achieved. Stock options and the remaining RSUs granted during the three and six months ended June 30, 2024 have only service-based criteria and vest over four years. Included in the RSUs for the six months ended June 30, 2023 are 502,225 shares with performance conditions (the “March 2023 PSUs”), which are related to regulatory approval of ELEVIDYS and achievement of a certain financial performance target, both of which were achieved in 2023. Vesting of the March 2023 PSUs is contingent on the fulfillment of remaining service conditions.

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense	$ 50.5	$ 47.4	$ 91.2	$ 88.6
Grants, Stock options	5,100	54,575	321,478	1,084,924
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Grants, Stock options	8,860		97,460	502,225	38,500

Stock-Based Compensation - Su_3

Stock-Based Compensation - 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		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 50,500	$ 47,400	$ 91,200	$ 88,600
Total stock-based compensation expense included in expenses		50,482	47,377	91,174	88,627
Subtotal		55,654	47,377	100,859	88,627
Capitalized stock-based compensation costs	[1]	(5,172)	0	(9,685)	0
Research and Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		19,806	21,577	36,079	37,990
Selling, General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		30,676	25,800	55,095	50,637
Employee Stock Option
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		15,515	21,135	31,796	44,965
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		37,808	25,037	65,335	41,177
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		$ 2,331	$ 1,205	$ 3,728	$ 2,485
[1] Prior to the six months ended June 30, 2024 , capitalized stock-based compensation costs were not material.

Other Income (Loss), Net - Summ

Other Income (Loss), Net - Summary of Other Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Nonoperating Income (Expense) [Abstract]
Accretion of investment discount, net	$ 10,766	$ 12,786	$ 23,570	$ 22,825
Interest income	8,076	8,418	15,169	17,694
Interest expense	(4,832)	(5,224)	(8,998)	(11,547)
Change in the fair value of contingent consideration	0	800	(10,100)	800
Other, net	268	154	1,180	(131)
Other income, net	14,278	16,934	20,821	29,641
Gain from sale of Priority Review Voucher	0	102,000	0	102,000
Loss on debt extinguishment	0	0	0	(387,329)
Total other income (loss), net	$ 14,278	$ 118,934	$ 20,821	$ (255,688)

INCOME TAXES (Additional Inform

INCOME TAXES (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Provision for Income tax	$ 7,117	$ 9,355	$ 12,446	$ 13,400
Effective tax rate			22.60%	(2.50%)
Federal tax expense		2,900		$ 2,900
State tax expense		$ 10,500		$ 10,500

Leases (Additional Information)

Leases (Additional Information) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Right of use assets	$ 124,001	$ 129,952

Earning (Loss) Per Share - Basi

Earning (Loss) Per Share - Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net Income (Loss)	$ 6,460	$ 36,119	$ (23,940)	$ (516,755)	$ 42,579	$ (540,695)
Add: interest expense, net of tax, on the Company's convertible debt	340		0		769	0
Net income (loss) - diluted	$ 6,800		$ (23,940)		$ 43,348	$ (540,695)
Weighted-average common shares outstanding - basic	94,618		88,743		94,305	88,466
Common stock issuable under the Company's equity incentive plans	3,095		0		3,388	0
Common stock issuable under the Company's convertible debt	1,431		0		1,436	0
Weighted-average common shares outstanding - diluted	99,144		88,743		99,129	88,466
Earnings (loss) per common share, basic	$ 0.07		$ (0.27)		$ 0.45	$ (6.11)
Earnings (loss) per common share, diluted	$ 0.07		$ (0.27)		$ 0.44	$ (6.11)

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Share (Parenthetical) (Detail) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable common stock	10,979	21,858

Earning (Loss) Per Share - Summ

Earning (Loss) Per Share - Summary of Potential Shares of Common Stock that were Excluded from the Computation of Diluted Earnings per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2024		Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable common stock	10,979		21,858
Equity Incentive Plans [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable common stock	2,879	[1]	12,316	[2]
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable common stock	8,100		9,542
[1] As of June 30, 2024, the anti-dilutive common stock issuable under the Company's equity incentive plans excludes 1.2 million shares that are dilutive but have performance or market conditions that were not met as of the end of the period. As of June 30, 2023, the anti-dilutive common stock issuable under the Company's equity incentive plans includes 1.2 million shares that have performance or market conditions that were not met as of the end of the period because these were anti-dilutive as the Company was in a net loss position at the end of the period .

Earning (Loss) Per Share - Su_2

Earning (Loss) Per Share - Summary of Potential Shares of Common Stock that were Excluded from the Computation of Diluted Earnings per Share (Parenthetical) (Details) - shares shares in Millions	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Dilutive Securities, Shares	1.2	1.2

Commitments and Contingencies -

Commitments and Contingencies - Summary of Aggregate Non-Cancelable Contractual Obligations Arising from Manufacturing Obligations (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
Commitments And Contingencies [Line Items]
2024 (July-December)	$ 757,166
2025	230,756
2026	108,260
2027	77,630
2028	72,343
Total manufacturing commitments	$ 1,246,155	[1]
[1] Total manufacturing commitments include the Catalent, Inc. (“Catalent”) manufacturing and supply agreement, for which the Company has ROU assets and lease liabilities recorded on the unaudited condensed consolidated balance sheets as of June 30, 2024 .

SUBSEQUENT EVENTS (Additional I

SUBSEQUENT EVENTS (Additional Information) (Details) - Forecast [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024
Maximum [Member]
Subsequent Event [Line Items]
Research and development expense		$ 65
Minimum [Member]
Subsequent Event [Line Items]
Research and development expense	$ 55