Apellis Pharmaceuticals (APLS) 10-Q 31 Jul 23 2023 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Jul. 24, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Entity Registrant Name	APELLIS PHARMACEUTICALS, INC.
Entity Central Index Key	0001492422
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	001-38276
Entity Tax Identification Number	27-1537290
Entity Address, Address Line One	100 Fifth Avenue
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	617
Local Phone Number	977-5700
Entity Common Stock, Shares Outstanding		117,737,289
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Security 12b Title	Common Stock, $0.0001 par value per share
Trading Symbol	APLS
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 616,259	$ 551,801
Accounts receivable	110,913	7,727
Inventory	103,216	85,714
Prepaid assets	34,404	36,350
Restricted cash	1,085	1,273
Other current assets	26,809	36,658
Total current assets	892,686	719,523
Non-current assets:
Right-of-use assets	16,726	18,747
Property and equipment, net	5,339	6,148
Other assets	827	15,799
Total assets	915,578	760,217
Current liabilities:
Accounts payable	27,500	37,342
Accrued expenses	97,716	95,139
Current portion of development liability	43,769	29,504
Current portion of right-of-use liabilities	5,852	5,625
Total current liabilities	174,837	167,610
Long-term liabilities:
Long-term development liability	289,960	315,647
Convertible senior notes	92,883	92,736
Right-of-use liabilities	12,066	14,352
Other liabilities	429
Total liabilities	570,175	590,345
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized, and zero shares issued and outstanding at June 30, 2023 and December 31, 2022	0	0
Common stock, $0.0001 par value; 200,000 shares authorized at June 30, 2023 and December 31, 2022; 117,579 shares issued and outstanding at June 30, 2023, and 110,772 shares issued and outstanding at December 31, 2022	12	11
Additional paid-in capital	2,954,862	2,479,596
Accumulated other comprehensive loss	(796)	(875)
Accumulated deficit	(2,608,675)	(2,308,860)
Total stockholders' equity	345,403	169,872
Total liabilities and stockholders' equity	$ 915,578	$ 760,217

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, issued	117,579,000	110,772,000
Common stock, outstanding	117,579,000	110,772,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income/(Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue:
Revenue	$ 94,969	$ 16,322	$ 139,814	$ 30,703
Operating expenses:
Cost of sales	8,379	82	16,188	1,329
Research and development	95,658	101,661	205,684	192,606
General and administrative	111,373	63,203	213,466	114,390
Total operating expenses:	215,410	164,946	435,338	308,325
Net operating loss	(120,441)	(148,624)	(295,524)	(277,622)
Interest income	6,002	1,432	11,395	1,530
Interest expense	(7,341)	(8,448)	(14,869)	(16,986)
Other (expense)/income, net	(63)	149	(341)	(140)
Net loss before taxes	(121,843)	(155,491)	(299,339)	(293,218)
Income tax expense	194	486	476	1,694
Net loss	(122,037)	(155,977)	(299,815)	(294,912)
Other comprehensive gain/(loss):
Unrealized gain/(loss) on marketable securities		(766)		(818)
Foreign currency gain	(21)	(369)	79	(286)
Total other comprehensive income/(loss)	(21)	(1,135)	79	(1,104)
Comprehensive loss, net of tax	$ (122,058)	$ (157,112)	$ (299,736)	$ (296,016)
Net loss per common share, basic	$ (1.02)	$ (1.46)	$ (2.57)	$ (2.88)
Net loss per common share, diluted	$ (1.02)	$ (1.46)	$ (2.57)	$ (2.88)
Weighted-average number of common shares used in net loss per common share, basic	119,316	106,630	116,594	102,349
Weighted-average number of common shares used in net loss per common share, diluted	119,316	106,630	116,594	102,349
Product Revenue, Net [Member]
Revenue:
Revenue	$ 89,645	$ 15,654	$ 128,444	$ 27,763
Licensing and other revenue [Member]
Revenue:
Revenue	$ 5,324	$ 668	$ 11,370	$ 2,940

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Stockholder's Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2021	$ 198,662	$ 10	$ 1,857,430	$ (2,090)	$ (1,656,688)
Beginning balance, Shares at Dec. 31, 2021		97,524,000
Common Stock -follow-on-offering	380,120	$ 1	380,119
Common Stock -follow-on-offering, shares		8,564,000
Issuance of common stock upon exercise of stock options	4,000		4,000
Issuance of common stock upon exercise of stock options, shares		239,000
Vesting of restricted stock units, net of shares withheld for taxes	(2,416)		(2,416)
Vesting of restricted stock units, net of shares withheld for taxes. shares		113,000
Share-based compensation expense	20,773		20,773
Unrealized gain (loss) on available-for-sale investments	(52)			(52)
Net loss	(138,935)				(138,935)
Foreign currency gain (loss)	83			83
Ending balance at Mar. 31, 2022	462,235	$ 11	2,259,906	(2,059)	(1,795,623)
Ending balance, Shares at Mar. 31, 2022		106,440,000
Beginning balance at Dec. 31, 2021	198,662	$ 10	1,857,430	(2,090)	(1,656,688)
Beginning balance, Shares at Dec. 31, 2021		97,524,000
Unrealized gain (loss) on available-for-sale investments	(818)
Net loss	(294,912)
Foreign currency gain (loss)	(286)
Ending balance at Jun. 30, 2022	(334,418)	$ 11	2,289,201	(3,194)	(1,951,600)
Ending balance, Shares at Jun. 30, 2022		106,841,000
Beginning balance at Mar. 31, 2022	462,235	$ 11	2,259,906	(2,059)	(1,795,623)
Beginning balance, Shares at Mar. 31, 2022		106,440,000
Issuance of common stock upon exercise of stock options	4,770		4,770
Issuance of common stock upon exercise of stock options, shares		283,000
Vesting of restricted stock units, net of shares withheld for taxes	(536)		(536)
Vesting of restricted stock units, net of shares withheld for taxes. shares		26,000
Share-based compensation expense	22,530		22,530
Issuance of common stock to employee stock purchase plan	2,531		2,531
Issuance of common stock to employee stock purchase plan, shares		92,000
Unrealized gain (loss) on available-for-sale investments	(766)			(766)
Net loss	(155,977)				(155,977)
Foreign currency gain (loss)	(369)			(369)
Ending balance at Jun. 30, 2022	(334,418)	$ 11	2,289,201	(3,194)	(1,951,600)
Ending balance, Shares at Jun. 30, 2022		106,841,000
Beginning balance at Dec. 31, 2022	169,872	$ 11	2,479,596	(875)	(2,308,860)
Beginning balance, Shares at Dec. 31, 2022		110,772,000
Issuance of common stock and pre-funded warrants in common stock offering	384,387	$ 1	384,386
Issuance of common stock and pre-funded warrants in common stock offering, shares		4,008,000
Issuance of common stock upon exercise of stock options	17,718		17,718
Issuance of common stock upon exercise of stock options, shares		951,000
Vesting of restricted stock units, net of shares withheld for taxes	(10,999)		(10,999)
Vesting of restricted stock units, net of shares withheld for taxes. shares		448,000
Share-based compensation expense	28,823		28,823
Net loss	(177,778)				(177,778)
Foreign currency gain (loss)	100			100
Ending balance at Mar. 31, 2023	412,123	$ 12	2,899,524	(775)	(2,486,638)
Ending balance, Shares at Mar. 31, 2023		116,179,000
Beginning balance at Dec. 31, 2022	169,872	$ 11	2,479,596	(875)	(2,308,860)
Beginning balance, Shares at Dec. 31, 2022		110,772,000
Net loss	(299,815)
Foreign currency gain (loss)	79
Ending balance at Jun. 30, 2023	345,403	$ 12	2,954,862	(796)	(2,608,675)
Ending balance, Shares at Jun. 30, 2023		117,579,000
Beginning balance at Mar. 31, 2023	412,123	$ 12	2,899,524	(775)	(2,486,638)
Beginning balance, Shares at Mar. 31, 2023		116,179,000
Issuance of common stock upon exercise of stock options	22,334		22,334
Issuance of common stock upon exercise of stock options, shares		1,208,000
Vesting of restricted stock units, net of shares withheld for taxes	(27)		(27)
Vesting of restricted stock units, net of shares withheld for taxes. shares		119,000
Share-based compensation expense	29,277		29,277
Issuance of common stock to employee stock purchase plan	3,754		3,754
Issuance of common stock to employee stock purchase plan, shares		73,000
Net loss	(122,037)				(122,037)
Foreign currency gain (loss)	(21)			(21)
Ending balance at Jun. 30, 2023	$ 345,403	$ 12	$ 2,954,862	$ (796)	$ (2,608,675)
Ending balance, Shares at Jun. 30, 2023		117,579,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating Activities
Net loss	$ (299,815)	$ (294,912)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	58,101	43,303
Loss on disposal of fixed assets	19
Amortization of right-of-use assets	(37)	(61)
Depreciation expense	846	763
Amortization of discounts for convertible notes, net of financing costs	147	290
Accretion of discount to development liability	13,078	13,336
Other liabilities		1,571
Changes in operating assets and liabilities:
Accounts receivable	(103,186)	2,584
Inventory	(17,502)	(32,134)
Prepaid assets	2,535	3,390
Other current assets	9,846	42,225
Other assets	14,977	15,757
Accounts payable	(9,849)	2,591
Accrued expenses	3,065	(17,287)
Net cash used in operating activities	(327,775)	(218,584)
Investing Activities
Purchase of property and equipment	(631)	(477)
Purchase of available-for-sale securities		(331,863)
Proceeds from maturity of available-for-sale securities		143,320
Net cash (used in) provided by investing activities	(631)	(189,020)
Financing Activities
Proceeds from issuance of common stock, net of issuance costs	384,387	380,120
Payments for development liability	(24,500)	(16,500)
Proceeds from exercise of stock options	40,052	8,770
Proceeds from issuance of common stock under employee share purchase plan	3,754	2,531
Payments of employee tax withholding related to equity-based compensation	(11,027)	(2,952)
Net cash provided by financing activities	392,666	371,969
Effect of exchange rate changes on cash, cash equivalents and restricted cash	9	(365)
Net decrease in cash, cash equivalents and restricted cash	64,269	(36,000)
Cash, cash equivalents and restricted cash at beginning of period	553,075	641,755
Cash, cash equivalents and restricted cash at end of period	617,344	605,755
Reconciliation of cash, cash equivalents and restricted cash to the consolidated balance sheets:
Cash and cash equivalents	616,259	604,489
Restricted cash	1,085	1,266
Total cash, cash equivalents, and restricted cash	617,344	605,755
Supplemental Disclosure of Financing Activities
Cash paid for interest	1,643	3,360
Cash paid for income taxes	$ 384	$ 156

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (122,037)	$ (177,778)	$ (155,977)	$ (138,935)	$ (299,815)	$ (294,912)

Insider Trading Arrangements

Insider Trading Arrangements	6 Months Ended
	Jun. 30, 2023 shares
Lucas Scheibler [Member]
Trading Arrangements, by Individual
Name	Lucas Scheibler
Title	Chief Innovation Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/15/2023
Aggregate Available	125,849
David Watson [Member]
Trading Arrangements, by Individual
Name	David Watson
Title	General Counsel
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/18/2023
Aggregate Available	26,555
Cedric Francois [Member]
Trading Arrangements, by Individual
Name	Cedric Francois
Title	President and Chief Executive
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/25/2023
Aggregate Available	300,000
Adam Townsend [Member]
Trading Arrangements, by Individual
Name	Adam Townsend
Title	Chief Commercial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/25/2023
Aggregate Available	110,000
Stephanie O Brien [Member]
Trading Arrangements, by Individual
Name	Stephanie O Brien
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/26/2023
Aggregate Available	22,500
Jeffrey Eisele [Member]
Trading Arrangements, by Individual
Name	Jeffrey Eisele
Title	Chief Development Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	5/30/2023
Aggregate Available	63,683
A Sinclair Dunlop [Member]
Trading Arrangements, by Individual
Name	A Sinclair Dunlop
Title	Director
Rule 10b5-1 Arrangement Terminated	true
Termination Date	5/31/2023
Nur Nicholson [Member]
Trading Arrangements, by Individual
Name	Nur Nicholson
Title	Chief Technical Operations
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	6/8/2023
Aggregate Available	67,000
Pascal Deschatelets [Member]
Trading Arrangements, by Individual
Name	Pascal Deschatelets
Title	Chief Scientific Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	6/9/2023
Aggregate Available	138,214
Karen L Lewis [Member]
Trading Arrangements, by Individual
Name	Karen L Lewis
Title	Chief People Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	6/26/2023
Aggregate Available	92,182

Nature of Organization and Oper

Nature of Organization and Operations	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Organization and Operations	1. Nature of Organization and Operations Apellis Pharmaceuticals, Inc. (the “Company”) is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutic compounds to treat diseases with high unmet needs through the inhibition of the complement system, which is an integral component of the immune system, at the level of C3, the central protein in the complement cascade. The Company was incorporated in September 2009 under the laws of the State of Delaware. The Company’s principal executive offices are located in Waltham, Massachusetts. The Company’s operations since inception have been limited to organizing and staffing the Company, acquiring rights to product candidates, business planning, raising capital, developing its product candidates, commercializing EMPAVELI (pegcetacoplan) for the treatment of paroxysmal nocturnal hemoglobinuria (“PNH”) and the commercializing of SYFOVRE (pegcetacoplan injection) for the treatment of geographic atrophy secondary to age-related macular degeneration (“GA”). The Company is subject to risks common in the biotechnology industry including, but not limited to, raising additional capital, development by its competitors of new technological innovations, its ability to successfully complete preclinical and clinical development of product candidates and receive timely regulatory approval of products, market acceptance of the Company’s products, protection of proprietary technology, healthcare cost containment initiatives, and compliance with governmental regulations, including those of the U.S. Food and Drug Administration (“FDA”). Liquidity and Going Concern The accompanying unaudited condensed consolidated financial statements have been prepared on the basis of the realization of assets and t he satisfaction of liabilities and commitments in the normal course of business. From inception to June 30, 2023, the Company has incurred cash outflows from operations, losses from operations and had an accumulated deficit of $ 2.6 billion primarily as a result of expenses incurred through a combination of research and development activities related to our various product candidates and expenses supporting those activities. As of July 31, 2023, the date of issuance of these unaudited condensed consolidated financial statements, the Company believes that its cash and cash equivalents of $ 616.3 million as of June 30, 2023 combined with its cash flows generated from sales will be sufficient to fund its operations and capital expenditures for at least the next twelve months. The Company’s future viability beyond that point is dependent on its ability to achieve commercial success for SYFOVRE and EMPAVELI. There are uncertainties associated with the Company’s ability to (1) obtain additional debt or equity financing on terms that are favorable to the Company, (2) enter into collaborative agreements with strategic partners, and (3) succeed in its future operations. If the Company is not able to obtain the required funding for its operations or is not able to obtain funding on terms that are favorable to the Company, it could be forced to delay, reduce or eliminate its research and development programs or future commercialization efforts and its business could be materially harmed.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”), for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted and, accordingly, the consolidated balance sheet as of December 31, 2022 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and six months ended June 30, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other interim period or for any other future year. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 21, 2023 (the “2022 Form 10-K”). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: development liability, accrued expenses, prepaid expenses, convertible debt and taxes. Summary of Significant Accounting Policies Reference is made to Note 2 Summary of Significant Accounting Policies in our 2022 Form 10-K for a detailed description of significant accounting policies. There have been no significant changes to our accounting policies as disclosed in our 2022 Form 10-K.

Product Revenues, Accounts Rece

Product Revenues, Accounts Receivable, and Reserves for Product Sales	6 Months Ended
	Jun. 30, 2023
Product Revenues Accounts Receivable And Reserves For Product Sales [Abstract]
Product Revenues, Accounts Receivable, and Reserves for Product Sales	3. Product Revenues, Accounts Receivable, and Reserves for Product Sales The Company received FDA approval for the sale of EMPAVELI in the United States in May 2021 and approval for the sale of SYFOVRE in the United States in February 2023. The Company’s product revenues, net of sales discounts and allowances and reserves, for the three months ended June 30, 2023 and 2022 were $ 89.6 million and $ 15.7 million, respectively. The Company’s product revenues, net of sales discounts and allowances and reserves, for the six months ended June 30, 2023 and 2022 were $ 128.4 million and $ 27.8 million, respectively. The Company’s product revenues consist of sales of EMPAVELI and SYFOVRE to specialty pharmacies and specialty distributors. The table reflects product revenue by major source for the following periods (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Products: EMPAVELI $ 22,303 $ 15,654 $ 42,742 $ 27,763 SYFOVRE 67,342 — 85,702 — Total Product revenue, net $ 89,645 $ 15,654 $ 128,444 $ 27,763 The Company’s accounts receivable balance of $ 110.9 million as of June 30, 2023 and $ 7.7 million as of December 31, 2022, consisted of EMPAVELI and SYFOVRE product sales receivable and licensing and other revenue receivables from our collaboration with Sobi. The Company does not have a reserve related to expected credit losses against its receivable balance. The Company’s product sales reserves totaled $ 10.4 million and $ 2.4 million as of June 30, 2023 and December 31, 2022, respectively. These amounts are included in accrued expenses on the Company’s unaudited condensed consolidated balance sheet. Th e following table summarizes activity in each of the product revenue allowance and reserve categories for the three and six months ended June 30, 2023 (in thousands): Chargebacks, Discounts, and Fees Government and other rebates Returns Total Ending balance at December 31, 2022 $ 164 $ 1,936 $ 251 2,351 Provision related to sales in the current year 1,466 2,566 651 4,683 Adjustments related to prior period sales — ( 2 ) ( 249 ) ( 251 ) Credits and payments made ( 184 ) ( 1,639 ) — ( 1,823 ) Ending balance at March 31, 2023 $ 1,446 $ 2,861 $ 653 $ 4,960 Provision related to sales in the current year 3,944 5,114 1,588 10,646 Adjustments related to prior period sales ( 84 ) 30 ( 416 ) ( 470 ) Credits and payments made ( 1,668 ) ( 2,946 ) ( 141 ) ( 4,755 ) Ending balance at June 30, 2023 $ 3,638 $ 5,059 $ 1,684 $ 10,381 Significant customers - Gross product revenues and product sales receivable from the Company's customers who individually accounted for 10% of more of total gross product revenues and/or 10% or more of total product sales receivable consisted of the following: Percent of Total Gross Product Revenues Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Customer A 24 % 99 % 33 % 99 % Customer C 13 % — 12 % — Customer D 58 % — 50 % — Percent of Product Sales Receivable As of June 30, 2023 2022 Customer A 8 % 99 % Customer C 16 % — Customer D 69 % —

Inventory

Inventory	6 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Inventory	4. Inventory The Company’s inventory consisted of the following as of June 30, 2023, and December 31, 2022 (in thousands): June 30, December 31, 2023 2022 Raw materials $ 32,711 $ 29,847 Semi-finished goods 48,368 54,101 Finished goods 22,137 1,766 Total Inventories $ 103,216 $ 85,714

Prepaid and Other Current Asset

Prepaid and Other Current Assets	6 Months Ended
	Jun. 30, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid and Other Current Assets	5. Prepaid and Other Current Assets Prepaid and other current assets consisted of the following as of June 30, 2023, and December 31, 2022 (in thousands): June 30, December 31, 2023 2022 Down payments for inventory $ 3,644 $ 13,987 Prepaid research and development 18,964 15,181 Other prepaid expenses 11,796 7,182 Total prepaid expenses $ 34,404 $ 36,350 June 30, December 31, 2023 2022 Royalties receivable $ 2,386 $ 1,442 ERC credit — 8,711 Receivable from collaboration agreement 15,000 20,000 Deposits and other current assets 9,423 6,505 Total other current assets $ 26,809 $ 36,658 Under the provisions of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) signed into law on March 27, 2020 and the subsequent extension of the CARES Act, the Company was eligible for a refundable employee retention credit (“ERC”) subject to certain criteria. The ERC provides eligible employers with less than 500 employees a refundable tax credit against the employer’s share of social security taxes. The ERC is equal to 70% of qualified wages paid to employees during 2021 calendar year for a maximum credit of $7,000 per employee for each calendar quarter through September 30, 2021. In November 2022, the Company filed for an $8.7 million refund under the CARES Act relating to the ERC. The full refund amount was received in the current period.

Development Liability

Development Liability	6 Months Ended
	Jun. 30, 2023
Research and Development [Abstract]
Development Liability	6. Development Liability On February 28, 2019, the Company entered into a development funding agreement (the “SFJ agreement”), with SFJ Pharmaceuticals Group (“SFJ”), under which SFJ agreed to provide funding to the Company to support the development of pegcetacoplan for the treatment of patients with PNH. Pursuant to the SFJ agreement, SFJ paid the Company $ 60.0 million following the signing of the agreement and agreed to pay the Company up to an additional $ 60.0 million in the aggregate in three equal installments upon the achievement of specified development milestones with respect to the Company’s Phase 3 program for pegcetacoplan in PNH. On June 7, 2019, the Company and SFJ amended the SFJ agreement, (such amendment, the “SFJ amendment”). Under the SFJ amendment, SFJ agreed to make an additional $ 20.0 million funding payment to the Company to support the development of systemic pegcetacoplan for the treatment of patients with PNH. As of January 29, 2020, the Company had received a total of $ 140.0 million from SFJ as the Company met milestones as identified in the SFJ agreement. The Company did not receive any additional funds from SFJ after January 29, 2020. Under the SFJ agreement, following regulatory approval by the FDA in May 2021 for the use of systemic pegcetacoplan as a treatment for PNH, the Company became obligated to pay SFJ an initial payment of $ 4.0 million and then an additional $ 226.0 million in the aggregate in six additional annual payments with the majority of the payments being made from the third anniversary to the sixth anniversary of regulatory approval. The Company paid SFJ the initial payment of $ 4.0 million in June 2021, its first annual payment of $ 11.5 million in May 2022 and its second annual payment of $ 24.5 million in May 2023. The subsequent annual payments remaining are due and payable in May of each year from 2024 through 2027. Following regulatory approval of systemic pegcetacoplan by the European Medicines Agency (“EMA”) in December 2021, the Company became obligated to pay SFJ an initial payment of $ 5.0 million and then an additional $ 225.0 million in the aggregate in six additional annual payments with the majority of the payments being made from the third anniversary to the sixth anniversary of regulatory approval. The Company paid SFJ the initial payment of $ 5.0 million in January 2022 and the first annual payment of $ 18.0 million in December 2022. The subsequent annual payments are due and payable in December of each year from 2023 through 2027. The Company has paid SFJ a total of $ 63.0 million as of June 30, 2023. Additionally, the Company granted a security interest to SFJ in all of its assets, excluding intellectual property and license agreements to which it is a party. In connection with the grant of the security interest, the Company agreed to certain affirmative and negative covenants, including restrictions on its ability to pay dividends, incur additional debt or enter into licensing transactions with respect to its intellectual property, other than specified types of licenses. From December 15, 2021 to the final annual payment due in December 2027, the development liability will be accreted from its initial carrying amount to the total payment amount using the effective interest rate method under the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 835, Interest, over the remaining life of the SFJ agreement. The difference between the carrying amount and the total payment amount is presented as a discount to the development liability. The accretion is recorded as interest expense in the unaudited condensed consolidated statement of operations. The following table summarizes the development liability (in thousands): June 30, 2023 December 31, 2022 Effective Development liability $ 397,000 $ 421,500 7.91 % Less: Unamortized discount to development liability ( 63,271 ) ( 76,349 ) Less: Current portion of development liability, net of discount ( 43,769 ) ( 29,504 ) Total long term development liability $ 289,960 $ 315,647 For the three and six months ended June 30, 2023 , interest expense of $ 6.5 million and $ 13.1 million, respectively, was recorded for the accretion of the development liability. Future minimum SFJ payments as of June 30, 2023 are as follows (in thousands): 2023 $ 31,000 2024 98,750 2025 103,000 2026 109,000 2027 55,250 Total future minimum payments $ 397,000

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2023
Payables and Accruals [Abstract]
Accrued Expenses	7. Accrued Expenses Accrued expenses consisted of the following as of June 30, 2023 and December 31, 2022, (in thousands): June 30, December 31, 2023 2022 Accrued research and development $ 31,240 $ 34,849 Accrued royalties 3,357 907 Accrued payroll liabilities 39,744 43,212 Other 23,375 16,171 Total $ 97,716 $ 95,139

Long-term Debt

Long-term Debt	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Long-term Debt	8. Long-term Debt Convertible Senior Notes On September 16, 2019, the Company completed a private offering of convertible notes (the “2019 Convertible Notes”) with an aggregate principal amount of $ 220.0 million issued pursuant to an indenture (the “Indenture”) with U.S. Bank National Association, as trustee. The net proceeds from the sale of the 2019 Convertible Notes were approximately $ 212.9 million after deducting the initial purchasers’ discounts and commissions of $ 6.6 million and offering expenses of $ 0.5 million. The Company used $ 28.4 million of the net proceeds from the sale of the 2019 Convertible Notes to pay the cost of the capped call transactions in September 2019 described below. On May 12, 2020, the Company issued convertible notes (the “2020 Convertible Notes”) with an aggregate principal amount of $ 300.0 million. The net proceeds from the sale of the 2020 Convertible Notes were approximately $ 322.9 million after deducting the purchasers’ discounts and commission of $ 5.7 million and offering expenses of $ 0.3 million. The Company used $ 43.1 million of the net proceeds from the sale to pay the cost of the additional capped call transactions in May 2020 described below. The 2019 Convertible Notes and the 2020 Convertible Notes are referred to together as the Convertible Notes. The Convertible Notes are senior unsecured obligations of the Company and bear interest at a rate of 3.5 % per year payable semiannually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020. The Convertible Notes will mature on September 15, 2026 , unless converted earlier, redeemed or repurchased in accordance with their terms. The Convertible Notes are convertible into shares of the Company’s common stock at an initial conversion rate of 25.3405 shares per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of approximately $39.4625 per share of common stock). The conversion rate is subject to customary anti-dilution adjustments. In addition, following certain events that occur prior to the maturity date or if the Company delivers a notice of redemption, the Company will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such corporate event or a notice of redemption, as the case may be, in certain circumstances as provided in the Indenture. Prior to March 15, 2026, the Convertible Notes are convertible only under the following circumstances: • during any calendar quarter, if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; • during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the Convertible Notes for each such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; • if the Company calls any or all of the Convertible Notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or • upon the occurrence of corporate events specified in the Indenture. On or after March 15, 2026 until the close of business on the second scheduled trading day immediately preceding the maturity date of the Convertible Notes, holders may convert the Convertible Notes at any time regardless of the foregoing circumstances. Upon conversion of the Convertible Notes, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock or a combination of cash and shares of common stock, at the Company’s election. Prior to September 20, 2023, the Company may not redeem the Convertible Notes. The Company may redeem for cash all or a portion of the Convertible Notes, at its option, on or after September 20, 2023 if the last reported sale price of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides a notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption. The redemption price will be equal to 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date If the Company undergoes a “fundamental change,” as defined in the Indenture, prior to maturity, subject to certain conditions, holders may require the Company to repurchase for cash all or any portion of their Convertible Notes at a fundamental change repurchase price equal to 100 % of the principal amount of the notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The Company used an effective interest rate of 10.5% to determine the liability component of the 2019 and 2020 Convertible Notes. This resulted in the recognition of $145.1 million and $204.5 million as the liability component of the 2019 and 2020 Convertible Notes, respectively, and the recognition of the residual amount of $74.9 million and $95.5 million as the debt discount with a corresponding increase to additional paid in capital for the equity component of the 2019 and 2020 Convertible Notes, respectively. The 2020 Convertible Notes aggregate debt issuance costs of $6.0 million were allocated to the liability and equity components in the amounts of $3.7 million and $2.3 million, respectively. The 2019 Convertible Notes aggregate debt issuance costs of $7.1 million were allocated to the liability and equity components in the amounts of $4.7 million and $2.4 million, respectively. Effective January 1, 2021, the Company adopted Accounting Standards Update 2020-06 using the modified retrospective method. Upon adoption, the Company increased net debt and reduced net equity by $149.7 million. The $149.7 million consisted of several items. The first item is the reclassification from equity to debt of the residual amounts originally identified as the equity components of the 2019 and 2020 Convertible Notes of $74.9 million and $95.5 million, respectively. The equity component reclassification was offset by the adjustment to retained earnings for the reversal of previous non-cash interest expense recorded for the amortization of the equity components of $17.1 million. The second item is the reclassification from equity to debt of the debt issuance costs originally allocated to equity for the 2019 and 2020 Convertible Notes of $2.4 million and $2.3 million, respectively. The debt issuance costs reclassification was offset by the adjustment to retained earnings for previous amortization of the debt issuance costs recorded of $1.1 million. In January 2021, July 2021 and July 2022, the Company entered into separate, privately negotiated exchange agreements to modify the conversion terms with certain holders of its 2019 Convertible Notes and 2020 Convertible Notes. Under the terms of these exchange agreements, in January 2021, July 2021 and July 2022, the holders exchanged approximately $ 126.1 million of 2019 Convertible Notes, $ 201.1 million of 2019 Convertible Notes and 2020 Convertible Notes, and $ 98.1 million of 2020 Convertible Notes, respectively, in aggregate principal amount held by them for an aggregate of 3,906,869 shares, 5,992,217 shares and 3,027,018 shares, respectively, of common stock issued by the Company. In accordance with FASB ASC Topic 470-20, “ Debt – Debt with Conversion and Other Options,” (“ASC 470-20”) the Company accounted for the exchange as an induced conversion based on the short period of time the conversion offer was open and the substantive conversion feature offer. The Company accounted for the conversion of the debt as an inducement by expensing the fair value of the shares that were issued in excess of the original terms of the Convertible Notes. As a result of the January 2021 exchange transactions, the Company reduced net debt outstanding and increased net equity on the consolidated balance sheet by $ 122.8 million, consisting of the par value of the 2019 Convertible Notes exchanged of $ 126.1 million less the $ 3.3 million of remaining debt issuance costs associated with the exchanged notes. The Company also increased shares outstanding by 3,906,869 shares consisting of 3,196,172 shares issued at the initial conversion rate in the Indenture of 25.3405 plus an additional 710,697 shares. Additionally, the Company issued 69,491 shares as settlement of debt issuance costs paid to the Company’s financial advisor in connection with the exchange transaction. For the three months ended March 31, 2021, the Company recorded a loss on conversion of debt of $ 39.5 million comprised of $ 36.4 million related to the value of the shares issued in excess of the original conversion terms at the fair market value and $ 3.1 million for the value of the 69,491 shares issued in payment of issuance costs at their then fair value. Upon exchange of the 2019 Convertible Notes, the holders forfeited accrued interest through the date of the exchange of $ 1.7 million, which the Company charged to interest expense and to equity. As a result of the July 2021 exchange transactions, the Company reduced net debt outstanding and increased net equity on the consolidated balance sheet by $ 197.0 million, consisting of the par value of the Convertible Notes exchanged of $ 201.1 million less the $ 4.1 million of remaining debt issuance costs associated with the exchanged notes. The Company also increased shares outstanding by 5,992,217 shares consisting of 5,097,166 shares issued at the initial conversion rate in the Indenture of 25.3405 plus an additional 895,051 shares. Additionally, the Company issued 78,419 shares as settlement of issuance costs paid to the Company’s financial advisor in connection with the exchange transaction. For the three months ended September 30, 2021, th e Company recorded a loss on conversion of debt of $ 61.1 million comprised of $ 55.9 million related to the value of the shares issued in excess of the original conversion terms at the fair market value and $ 5.2 million for the value of the 78,419 shares issued in payment of issuance costs at their then fair value. Upon exchange of the Convertible Notes, the holders forfeited accrued interest through the date of the exchange of $ 2.5 million, which the Company charged to interest expense and to equity. As a result of the July 2022 exchange transactions, the Company reduced net debt outstanding and increased net equity on the consolidated balance sheet by $ 96.8 million, consisting of the par value of the Convertible Notes exchanged of $ 98.1 million less the $ 1.3 million of remaining debt issuance costs associated with the exchanged notes. The Company also increased shares outstanding by 3,027,018 shares consisting of 2,485,548 shares issued at the initial conversion rate in the Indenture of 25.3405 plus an additional 541,470 shares. Additionally, the Company issued 46,132 shares as settlement of issuance costs paid to the Company’s financial advisor in connection with the exchange transaction. For the three months ended September 30, 2022, the Company recorded a loss on conversion of debt of $ 32.9 million comprised of $ 30.4 million related to the value of the shares issued in excess of the original conversion terms at the fair market value and $ 2.5 million for the value of the 46,132 shares. The conditional conversion feature of the Convertible Notes was triggered as of June 30, 2021, and as a result the Convertible Notes were convertible at the option of the holders until September 30, 2021. During this period, certain holders of the Convertible Notes converted approximately $0.7 million of aggregate principal amount of Convertible Notes into an aggregate of 18,775 shares, which were issued in October 2021. The conditional conversion feature of the Convertible Notes was triggered as of March 31, 2023, and as a result the Convertible Notes were convertible at the option of the holders until June 30, 2023. No Convertible Notes were converted during this period. The conditional conversion feature of the Convertible Notes was triggered as of June 30, 2023, and as a result the Convertible Notes became convertible at the option of the holders until September 30, 2023. Through the date of issuance of these financial statements, no Convertible Notes were converted. As of June 30, 2023 , the Company held in treasury Convertible Notes in principal amount of $ 425.4 million which notes had not been cancelled. The outstanding balance of the Convertible Notes as of June 30, 2023 and December 31, 2022 consisted of the following (in thousands): June 30, December 31, 2023 2022 Liability Principal 93,897 93,897 Less: debt discount and issuance costs, net ( 1,014 ) ( 1,161 ) Net carrying amount $ 92,883 $ 92,736 The following table sets forth total interest expense recognized related to the Convertible Notes during the three and six months ended June 30, 2023 and 2022 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Amortization of debt issuance costs $ 74 $ 145 $ 147 $ 290 Contractual interest expense 822 1,680 1,643 3,360 Total interest expense $ 896 $ 1,825 $ 1,790 $ 3,650 Future minimum payments on Convertible Notes payable as of June 30, 2023 are as follows (in thousands): 2023 $ 1,644 2024 3,286 2025 3,286 2026 96,225 Total future minimum payments 104,441 Less: interest ( 10,544 ) Less: debt discount and issuance costs, net ( 1,014 ) Less: current portion — Convertible senior notes $ 92,883 Capped Call Transactions On September 11, 2019 and May 6, 2020, concurrently with the pricing of the Convertible Notes, the Company entered into capped call transactions with two counterparties. The capped call transactions are expected generally to reduce the potential dilution to the Company’s common stock upon any conversion of Convertible Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Convertible Notes, as the case may be, in the event that the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, is greater than the strike price of the capped call transactions, which is initially $39.4625 (the conversion price of the Convertible Notes) and is subject to anti-dilution adjustments substantially similar to those applicable to the conversion rate of such Convertible Notes. If, however, the market price per share of the Company’s common stock, as measured under the terms of the capped call transactions, exceeds the cap price of the capped call transactions, which is initially $63.14 per share, there would nevertheless be dilution and/or there would not be an offset of such potential cash payments, in each case, to the extent that such market price exceeds the cap price of the capped call transactions. Pursuant to FASB ASC Topic 815-40 Derivatives and Hedging, the Company determined that the capped call transactions should be classified as equity instruments and the capped call premium paid in the amount of $ 28.4 million and $ 43.1 million were recorded as reductions to additional paid-in capital at December 31, 2021 for the 2019 Convertible Notes and the 2020 Convertible Notes, respectively.

Leases

Leases	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Leases	9. Leases The underlying assets of the Company’s leases primarily relate to office space leases, but also include some equipment leases. The Company determines if an arrangement qualifies as a lease at its inception. As a practical expedient permitted under FASB ASC Topic 842, Leases , the Company elected to account for the lease and non-lease components as a single lease component for all leases of which it is the lessee. Lease payments, which may include lease and non-lease components, are included in the measurement of the Company’s lease liabilities to the extent that such payments are either fixed amounts or variable amounts that depend on a rate or index as stipulated in the lease contract. When the Company cannot readily determine the rate implicit in the lease, the Company determines its incremental borrowing rate by using the rate of interest that it would have to pay to borrow on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company enters into lease agreements with terms generally ranging from 2 - 7 years . Some of the Company’s lease agreements include Company options to extend the lease on a month-to-month basis or for set periods for up to five years . Many of these leases also include options to terminate the leases within one year or per other contractual terms. Renewal and termination options were generally not included in the lease term for the Company’s existing operating leases. As of June 30, 2023 and December 31, 2022 , all leases were classified as operating lease assets and liabilities. Additional information related to the operating lease assets and liabilities is as follows (in thousands): June 30, December 31, 2023 2022 Operating Lease Assets $ 16,726 $ 18,747 Operating Lease Liabilities $ 17,918 $ 19,977 Weighted Average Remaining Term in years 3.12 3.57 Weighted Average discount rate used to measure 7.21 % 7.26 % For the three months ended June 30, 2023 and 2022, the total lease cost for operating lease expense was $ 1.7 million and $ 1.5 million, respectively. For the six months ended June 30, 2023 and 2022, the total lease cost for operating lease expense was $ 3.4 million and $ 2.9 million, respectively. Supplemental cash flow information related to operating leases for the six months ended June 30 2023 and 2022 is as follows (in thousands): 2023 2022 Operating cash flows from operating leases $ 4,094 $ 3,532 Operating lease assets obtained in exchange for lease obligations $ — $ — The maturities of the Company’s operating lease liabilities as of June 30, 2023 are as follows (in thousands): 2023 3,528 2024 6,416 2025 5,253 2026 4,339 2027 and thereafter 556 Total future minimum lease payments 20,092 Less Imputed interest ( 2,174 ) Total operating lease liabilities $ 17,918

Other Comprehensive Income and

Other Comprehensive Income and Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Other Comprehensive Income and Accumulated Other Comprehensive Income	10. Other Comprehensive Income and Accumulated Other Comprehensive Income The following tables summarize the changes in accumulated other comprehensive income/(loss), by component for the six months ended June 30, 2023 and 2022 (in thousands): Unrealized Gains (Losses) from Marketable Securities Foreign Currency Translation Adjustment Unrealized Gains (Losses) from Pension Plan Total Accumulated Other Comprehensive Income (Loss) Balances, December 31, 2022 — $ ( 2,521 ) $ 1,646 $ ( 875 ) Net other comprehensive income (loss) — 100 — 100 Balances, March 31, 2023 — ( 2,421 ) 1,646 ( 775 ) Net other comprehensive loss — ( 21 ) — ( 21 ) Balances, June 30, 2023 — ( 2,442 ) 1,646 ( 796 ) Unrealized Gains (Losses) from Marketable Securities Foreign Currency Translation Adjustment Total Accumulated Other Comprehensive Income (Loss) Balances, December 31, 2021 $ 1 $ ( 2,091 ) $ ( 2,090 ) Net other comprehensive income (loss) ( 52 ) 83 31 Balances, March 31, 2022 ( 51 ) ( 2,008 ) ( 2,059 ) Net other comprehensive loss ( 766 ) ( 369 ) ( 1,135 ) Balances, June 30, 2022 ( 817 ) ( 2,377 ) ( 3,194 )

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	11 . Fair Value Measurements The Company is required to disclose information on the fair value of financial instruments and inputs that enable an assessment of the fair value. The three levels of the fair value hierarchy prioritize valuation inputs based upon the observable nature of those inputs as follows: Level 1 – Quoted prices in active markets for identical assets or liabilities; Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. The following table presents the fair value of financial instruments recorded originally at amortized cost or fair value and not remeasured on a recurring basis (in thousands): June 30, 2023 Balance Sheet Classification Type of Instrument Level 1 Level 2 Level 3 Total Financial Assets: Cash and cash equivalents: Money market funds $ 454,793 $ — $ — $ 454,793 Total Financial Assets $ 454,793 $ — $ — $ 454,793 December 31, 2022 Balance Sheet Classification Type of Instrument Level 1 Level 2 Level 3 Total Financial Assets: Cash and cash equivalents Money market funds $ 527,728 $ — $ — $ 527,728 Total Financial Assets $ 527,728 $ — $ — $ 527,728 The Company’s Convertible Notes and development liability are financial instruments that are reported in the financial statements at historical cost. The Convertible Notes are Level 1 within the fair value level hierarchy as of June 30, 2023 and December 31, 2022. The fair value of the Convertible Notes was $ 218.9 million as of June 30, 2023 and $ 143.9 million as of December 31, 2022. The Convertible Notes accrue a semi-annual coupon at an annual rate of 3.5 %, which was included in accrued expenses in the consolidated balance sheets as of June 30, 2023 and December 31, 2022. The fair value of the development liability was $ 317.0 million and $ 315.8 million as of June 30, 2022 and December 31, 2022, respectively. The development liability is Level 2 within the fair value hierarchy based on the discounting of fixed cash flows using an observed bond yield for borrowers with similar credit rating.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes For the three and six months ended June 30, 2023, the Company recorded $ 0.2 million and $ 0.5 million of income tax expense, respectively, primarily pertaining to state and foreign income taxes. The income tax provision during interim periods is computed by applying an estimated annual effective tax rate to year-to-date pre-tax income, plus adjustments for significant unusual or infrequently occurring items, in accordance with FASB ASC Topic 740-270, Income Taxes – Interim Reporting . The income tax provision differs from the U.S. federal statutory rate of 21 % primarily due to the effect of valuation allowance against the Company’s net deferred tax assets, which reduces the Company’s net tax benefit. Deferred tax assets and deferred tax liabilities are determined based on temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company has recorded a full valuation allowance against its net deferred tax assets for the period ended June 30, 2023. The Company does not recognize a tax benefit for uncertain tax positions unless it is more likely than not that the position will be sustained upon examination by tax authorities, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The tax benefit that is recorded for these positions is measured at the largest amount of cumulative benefit that has greater than a 50 percent likelihood of being realized upon ultimate settlement. Deferred tax assets that do not meet these recognition criteria are not recorded and the Company recognizes a liability for uncertain tax positions that may result in tax payments. The Company has no t recorded any amounts for unrecognized tax benefits for the period ended June 30, 2023 . Our policy is to review and update unrecognized tax positions as facts and circumstances change.

License and Collaboration Agree

License and Collaboration Agreements	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreements	13. License and Collaboration Agreements Sobi License and Collaboration Agreement On October 27, 2020, the Company and its subsidiaries, Apellis Switzerland GmbH and APL DEL Holdings, LLC, entered into a Collaboration and License Agreement (the “Sobi collaboration agreement”) with Swedish Orphan Biovitrum AB (Publ) (“Sobi”), concerning the development and commercialization of pegcetacoplan and specified other structurally and functionally similar compstatin analogues or derivatives for use systemically or for local non-ophthalmological administration (collectively referred to as the “Licensed Products”). Under the Sobi collaboration agreement, the Company granted Sobi an exclusive (subject to certain retained rights of the Company), sublicensable license of certain patent rights and know-how to develop and commercialize Licensed Products in all countries outside of the United States. The Company retains the right to commercialize Licensed Products in the United States, and, subject to specified limitations, to develop Licensed Products worldwide for commercialization in the United States. Under the Sobi collaboration agreement, the Company and Sobi have agreed to collaborate to develop Licensed Products for the treatment of PNH, CAD, HSCT-TMA, C3G, and IC-MPGN, and any other indications subsequently agreed upon by the parties, for commercialization by or on behalf of the Company in the United States and by or on behalf of Sobi outside of the United States. If the parties do not agree to jointly pursue any development activities for the Licensed Products (whether for an Initial Indication or otherwise), the party proposing to pursue such activities may conduct such activities at its sole expense (with the non-proposing party having the right to obtain rights to the data generated by such development activities by paying a specified percentage of that expense), subject to agreed-upon exceptions that limit each party’s unilateral development rights. The initial development plan sets forth the initial development activities to be conducted by each of the Company and Sobi, with the Company bearing all costs incurred in conducting the activities set forth in such initial development plan, as well as certain specified additional costs that are not included in the initial development plan that may be incurred by the parties in developing Licensed Products for PNH in the European Union and the United Kingdom. The Company and Sobi have formed several governance committees to oversee the development and manufacture, and to review and discuss the commercialization, of Licensed Products. The Company shall supply Licensed Products to Sobi for development and for commercialization outside of the United States in accordance with a supply agreement to be negotiated by the parties. The Sobi collaboration agreement grants Sobi the right to perform or have performed drug product manufacturing of Licensed Products for development and for commercialization outside the United States and to manufacture or have manufactured drug substance under certain circumstances. Sobi paid the Company an upfront payment of $ 250.0 million in November 2020 and has agreed to pay up to an aggregate of $ 915.0 million upon the achievement of specified one-time regulatory and commercial milestone events, of which the Company received $ 50.0 million in April 2022 for the achievement of a regulatory development milestone in Europe. Sobi also agreed to reimburse the Company for up to $ 80.0 million in development costs, of which the Company received $ 25.0 million in January 2021, $ 20.0 million in January 2022 and $ 20.0 million in January 2023. The remaining $15.0 million is due from Sobi in January 2024. The Company will also be entitled to receive tiered, double-digit royalties (ranging from high teens to high twenties) on sales of Licensed Products outside of the United States, subject to customary deductions and third-party payment obligations, until the latest to occur of: (i) expiration of the last-to-expire of specified licensed patent rights; (ii) expiration of regulatory exclusivity; and (iii) ten ( 10 ) years after the first commercial sale of the applicable Licensed Product, in each case on a Licensed Product-by-Licensed Product and country-by-country basis. Under the Sobi collaboration agreement, the Company remains responsible for its license fee obligations (including royalty obligations) to the Trustees of the University of Pennsylvania (“Penn”), as a licensor of the Company and for its payment obligations to SFJ. Sobi Accounting Analysis The Company has determined that the Sobi collaboration agreement is within the scope of FASB ASC Topic 808, Collaborative Arrangement Guidance and Considerations (“ASC 808”), as a contractual arrangement that involves a joint operating activity whereby both parties are (i) active participants in the activity and (ii) exposed to certain significant risks and rewards dependent on the commercial success of the activity. ASC 808 does not address measurement or recognition matters but allows for analogizing to FASB ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). Pursuant to ASC 606, the Company performed the following five steps: (i) identified the contract(s) with a customer; (ii) identified the performance obligations in the contract; (iii) determined the transaction price; (iv) allocated the transaction price to the performance obligations in the contract; and (v) recognized revenue when (or as) the entity satisfies a performance obligation. The Company identified the following material distinct promises under the Sobi collaboration agreement: (1) licenses to develop and commercialize pegcetacoplan (“Licenses to IP”), and (2) performance of research and development services. The Company determined the promises to be distinct because Sobi can benefit from each of the license and the development services on their own or with readily available services. The Company could have provided the license without any development services and Sobi would have been able to benefit from it by obtaining development services from another provider as the Licensed Products are at a more mature stage in their life cycle. Under the Sobi collaboration agreement, Sobi agreed to pay the Company i) a fixed amount of $ 250.0 million in an upfront payment in November 2020; ii) a fixed amount of an additional $ 80.0 million in development reimbursements, payable yearly in four tranches in amounts determined based upon actual expenses incurred by the Company; iii) up to an aggregate of $ 915.0 million upon the achievement of specified one-time regulatory and commercial milestone events; and iv) tiered, double-digit royalties, ranging from high teens to high twenties, on sales of Licensed Products outside of the United States, subject to customary deductions and third-party payment obligations. At contract inception, the $ 250.0 million non-refundable payment and the $ 80.0 million reimbursements were fixed proceeds. The Company evaluated whether Sobi is a customer for either of the distinct promises in the Sobi collaboration agreement. Under the Licenses to IP, the Company determined that Sobi is a customer as the know-how provided and the right granted by the Company to Sobi are outputs of the Company’s business activities for which the Company will receive consideration. With respect to research and development activity, management determined that there is no vendor relationship as performing research and development activities for others is not a part of the Company’s ongoing central operations. Based upon the evaluation of the relative fair values, the Company allocated the purchase price of $ 250.0 million and the related milestones and royalties to the License to IP and $ 80.0 million to performance of research and development activities. The milestone and royalty payments are subject to activities outside the control of the Company. Per ASC 606, the Company considers this to be a customer/ vendor relationship, therefore, the Company will include the regulatory milestone payments in the total transaction price when it is probable that a significant reversal of revenue would not occur in a future period. The Company will recognize commercial milestone and royalty revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which the commercial milestone or royalty has been allocated has been satisfied. In case of commercial milestone or royalty payments, the Company will recognize revenue in the same period that the sales are completed for which the Company is contractually entitled to the milestone or percentage-based royalty payment. To date, the Company has not recognized any commercial milestone revenue resulting from any of its licensing arrangements. The Company has recognized $ 2.4 million and $ 4.0 million of royalty revenue for the three and six months ended June 30, 2023, respectively. Management periodically assesses the elements of the contract and re-evaluates revenue recognition as necessary. Pursuant to ASC 606, during the year ended December 31, 2020, the Company recognized the $ 250.0 million in revenue as this is the amount allocated to the license. The $ 80.0 million reimbursement for research and development activities does not constitute a customer/vendor relationship and thus is not in the scope of ASC 606. As ASC 808 does not include recognition guidance, the Company has established an accounting policy to recognize the payments under the reimbursement as a receivable on the balance sheet in an amount that is to be reimbursed based upon expense incurred by the Company, with a contra- research and development expense recognized in the consolidated statement of operations, over time as the expenses are incurred. Under the Sobi collaboration agreement, for the three and six months ended June 30, 2023 , the Company recognized $ 2.4 million and $ 4.0 million, respectively, of royalty revenue. For the three and six months ended June 30, 2022, the Company recognized $ 0.7 million and $ 0.8 million, respectively, of royalty revenue. For the three and six months ended June 30, 2023 , the Company did no t recognize any contra-research and development expense in the unaudited condensed consolidated statement of operations related to the $ 80.0 million reimbursement commitment from Sobi. For the six months ended June 30, 2022, the Company recognized $ 5.0 million for contra-research and development expense in the unaudited condensed consolidated statement of operations related to the $ 80.0 million reimbursement commitment from Sobi. The Company did no t recognize any contra-research and development expense for the three months ended June 30, 2022. As of June 30, 2023 , the Company recorded $ 15.0 million in current assets, which represents the receivable for contra-research and development expenses incurred but not yet reimbursed from Sobi. As of December 31, 2022, the Company recorded a receivable of $ 35.0 million, with $ 20.0 million in other current assets and $ 15.0 million in other assets on the consolidated balance sheet. The total receivable balance as of December 31, 2022 is for contra-research and development expenses incurred but not yet reimbursed from Sobi. The Company received the $ 20.0 million recorded in other current assets in January 2023. University of Pennsylvania License Agreement The Company is a party to a license agreement with Penn for an exclusive, worldwide license to specified patent rights. The Company is required to pay annual maintenance fees of $ 0.1 million until the first sale of a licensed product. The Company is also required to make milestone payments aggregating up to $ 3.2 million based upon the achievement of specified development and regulatory milestones and up to $ 5.0 million based upon the achievement of specified annual sales milestones with respect to each licensed product, and to pay low single-digit royalties based on net sales of each licensed product and with minimum quarterly royalty thresholds. In addition, the Company is obligated to pay a specified portion of income it receives from sublicensees. In addition, the Company is also party to a license agreement with Penn for an exclusive, worldwide license to specified patent rights for the development and commercialization of products in fields of use, as defined therein. The Company is required to pay annual maintenance fees of $ 0.1 million until the first sale of a licensed product. The Company is required to make milestone payments aggregating up to $ 1.7 million, based upon the achievement of development and regulatory approval milestones, and up to $ 2.5 million, based upon the achievement of annual sales milestones with respect to each of the first two licensed products. The license agreement also requires the Company to pay low single digit royalties based on net sales of each licensed product, subject to minimum quarterly royalty thresholds. In addition, the Company is obligated to pay a specified portion of income it receives from sublicensees. In January 2021, the Company paid $ 25.0 million for a sublicense fee owed to Penn related to the Sobi collaboration agreement and another licensing transaction. In August 2021, the Company paid $ 1.0 million to Penn upon the achievement of a development milestone, net of a credit for the annual license maintenance payment. In June 2022, the Company paid an additional $ 5.0 million to Penn upon the achievement of a development milestone, which was recognized in accrued expenses of December 31, 2021, as it was considered probable at that time. In January 2023, the Company paid $ 1.0 million to Penn upon the achievement of a sales milestone for EMPAVELI in 2022. In April 2023, the Company paid $ 2.3 million for the achievement of a regulatory milestone as a result of the FDA approval of SYFOVRE in February 2023. Beam Research Collaboration In June 2021, the Company entered into an exclusive five-year research collaboration (the “Beam collaboration agreement”) with Beam Therapeutics, Inc. (“Beam”) focused on the use of Beam’s proprietary base editing technology to discover new treatments for complement-driven diseases. The Company and Beam agreed to collaborate on up to six research programs focused on C3 and other complement targets in the eye, liver and brain. Under the terms of the Beam collaboration agreement, Apellis is responsible for selecting specific genes within the complement system in various organs including the eye, liver and brain (the “Target List”) and providing analytical support while Beam will apply its base editing technology and conduct preclinical research on up to six base editing programs for the Target List. During the first five years of the Beam collaboration agreement, Beam is prohibited from developing on its own or with a third party any base editing therapies associated with the items on the Target List but does not prevent Beam from licensing its intellectual property to a third-party for another purpose outside of the Target List. The Company will have exclusive rights to license each of the six programs and will assume responsibility for subsequent development and commercialization. Beam may elect to enter a 50-50 co-development and U.S. co-commercialization agreement with the Company with respect to any one program licensed under the Beam collaboration agreement and upon such election any license agreement in place at that time, would be terminated. As part of the Beam collaboration agreement, the Company agreed to pay a $ 50.0 million up-front, non-refundable payment to Beam, which the Company paid in July 2021. In June 2022, the Company paid $ 25.0 million, which was recorded as a cost of research collaboration expense for the year ended December 31, 2021, as it was considered probable of achievement. The Company and Beam are each responsible for their own costs during the research collaboration. If and after the opt-in license rights are exercised for each of the up to six programs, Beam will be eligible to receive development, regulatory and sales milestones from the Company, as well as royalty payments on sales. The Beam collaboration agreement has an initial term of five years and may be extended up to two years on a per year program-by-program basis. The Company analyzed the Beam collaboration agreement pursuant to ASC 808 to assess whether the agreement involved joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. Since each party is actively participating in this activity and exposed to significant risks and rewards related to the activity through each party’s costs will be accounted for under ASC 808. Since ASC 808 does not provide recognition guidance, the Company referred to the guidance under FASB ASC Topic 730, Research and Development (“ASC 730”), to arrangements involving payments by the Company. ASC 730 requires the Company to recognize research and developments costs as expense as incurred since the payment was made for the use of Beam’s intellectual property and research and development services and there is no alternative use.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	14. Commitments and Contingencies The Company has certain non-cancelable purchase obligations related to the manufacturing of drug substance and drug product, with Bachem Americas, Inc., under which the Company has agreed to purchase a significant portion of its requirements for the pegcetacoplan drug substance over the next five years and a commercial supply agreement with NOF Corporation, under which the Company has agreed to purchase activated polyethylene glycol derivative, or PEG, which is a component of pegcetacoplan. Under these agreements, as of June 30, 2023, the Company is obligated to pay up to an aggregate of $ 147.2 million to these vendors. In addition, the Company has other non-cancelable purchase agreements as of June 30, 2023, under which it is obligated to pay up to $ 21.7 million to vendors. The Company is a party to a master lease agreement under which the Company leases vehicles with initial terms of 36 months from the date of delivery. If the Company were unable to take delivery of a previously ordered vehicle, the Company may incur nominal fees . Indemnifications —In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend indemnified parties for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has no t incurred any cost to defend lawsuits or settle claims related to these indemnification provisions. Legal —During the normal course of business, the Company may be a party to legal claims that may not be covered by insurance. Management does not believe that any such claims would have a material impact on the Company’s consolidated financial statements.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Net Loss per Share	15. Net Loss per Share Basic and diluted net loss per share is calculated based upon the weighted average number of shares of common stock outstanding during the period. Shares of the Company’s common stock underlying pre-funded warrants are included in the calculation of basic and diluted earnings per share. Since the Company was in a loss position for all periods presented, basic net loss per common share is the same as diluted net loss per common share for all periods presented as the inclusion of all potential common shares outstanding would have been anti-dilutive. Convertible notes and shares outstanding presented below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, as their effect is anti-dilutive (in thousands): As of June 30, 2023 2022 Convertible notes 2,379 4,865 Common stock options 10,665 13,072 Restricted stock units 4,669 3,254 Total 17,713 21,191

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and following the requirements of the Securities and Exchange Commission (the “SEC”), for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted and, accordingly, the consolidated balance sheet as of December 31, 2022 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete financial statements. These financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair presentation of the Company’s financial information. The results of operations for the three and six months ended June 30, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other interim period or for any other future year. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 21, 2023 (the “2022 Form 10-K”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: development liability, accrued expenses, prepaid expenses, convertible debt and taxes.

Product Revenues, Accounts Re_2

Product Revenues, Accounts Receivable, and Reserves for Product Sales (Tables)	6 Months Ended
	Jun. 30, 2023
Product Revenues Accounts Receivable And Reserves For Product Sales [Abstract]
Schedule of Disaggregation of Product Revenue by Major Source	The table reflects product revenue by major source for the following periods (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Products: EMPAVELI $ 22,303 $ 15,654 $ 42,742 $ 27,763 SYFOVRE 67,342 — 85,702 — Total Product revenue, net $ 89,645 $ 15,654 $ 128,444 $ 27,763
Summary of Product Revenue Allowance and Reserve Categories	Th e following table summarizes activity in each of the product revenue allowance and reserve categories for the three and six months ended June 30, 2023 (in thousands): Chargebacks, Discounts, and Fees Government and other rebates Returns Total Ending balance at December 31, 2022 $ 164 $ 1,936 $ 251 2,351 Provision related to sales in the current year 1,466 2,566 651 4,683 Adjustments related to prior period sales — ( 2 ) ( 249 ) ( 251 ) Credits and payments made ( 184 ) ( 1,639 ) — ( 1,823 ) Ending balance at March 31, 2023 $ 1,446 $ 2,861 $ 653 $ 4,960 Provision related to sales in the current year 3,944 5,114 1,588 10,646 Adjustments related to prior period sales ( 84 ) 30 ( 416 ) ( 470 ) Credits and payments made ( 1,668 ) ( 2,946 ) ( 141 ) ( 4,755 ) Ending balance at June 30, 2023 $ 3,638 $ 5,059 $ 1,684 $ 10,381
Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable	Significant customers - Gross product revenues and product sales receivable from the Company's customers who individually accounted for 10% of more of total gross product revenues and/or 10% or more of total product sales receivable consisted of the following: Percent of Total Gross Product Revenues Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Customer A 24 % 99 % 33 % 99 % Customer C 13 % — 12 % — Customer D 58 % — 50 % — Percent of Product Sales Receivable As of June 30, 2023 2022 Customer A 8 % 99 % Customer C 16 % — Customer D 69 % —

Inventory (Tables)

Inventory (Tables)	6 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Schedule Of Inventory Current	The Company’s inventory consisted of the following as of June 30, 2023, and December 31, 2022 (in thousands): June 30, December 31, 2023 2022 Raw materials $ 32,711 $ 29,847 Semi-finished goods 48,368 54,101 Finished goods 22,137 1,766 Total Inventories $ 103,216 $ 85,714

Prepaid and Other Current Ass_2

Prepaid and Other Current Assets (Tables)	6 Months Ended
	Jun. 30, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Summary of Prepaid and Other Current Assets	Prepaid and other current assets consisted of the following as of June 30, 2023, and December 31, 2022 (in thousands): June 30, December 31, 2023 2022 Down payments for inventory $ 3,644 $ 13,987 Prepaid research and development 18,964 15,181 Other prepaid expenses 11,796 7,182 Total prepaid expenses $ 34,404 $ 36,350 June 30, December 31, 2023 2022 Royalties receivable $ 2,386 $ 1,442 ERC credit — 8,711 Receivable from collaboration agreement 15,000 20,000 Deposits and other current assets 9,423 6,505 Total other current assets $ 26,809 $ 36,658

Development Liability (Tables)

Development Liability (Tables)	6 Months Ended
	Jun. 30, 2023
Research and Development [Abstract]
Summary of Development Liability	The following table summarizes the development liability (in thousands): June 30, 2023 December 31, 2022 Effective Development liability $ 397,000 $ 421,500 7.91 % Less: Unamortized discount to development liability ( 63,271 ) ( 76,349 ) Less: Current portion of development liability, net of discount ( 43,769 ) ( 29,504 ) Total long term development liability $ 289,960 $ 315,647
Schedule of Future Minimum SFJ Payments	Future minimum SFJ payments as of June 30, 2023 are as follows (in thousands): 2023 $ 31,000 2024 98,750 2025 103,000 2026 109,000 2027 55,250 Total future minimum payments $ 397,000

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following as of June 30, 2023 and December 31, 2022, (in thousands): June 30, December 31, 2023 2022 Accrued research and development $ 31,240 $ 34,849 Accrued royalties 3,357 907 Accrued payroll liabilities 39,744 43,212 Other 23,375 16,171 Total $ 97,716 $ 95,139

Long-term Debt (Tables)

Long-term Debt (Tables)	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Schedule of Outstanding Balance of Convertible Notes	The outstanding balance of the Convertible Notes as of June 30, 2023 and December 31, 2022 consisted of the following (in thousands): June 30, December 31, 2023 2022 Liability Principal 93,897 93,897 Less: debt discount and issuance costs, net ( 1,014 ) ( 1,161 ) Net carrying amount $ 92,883 $ 92,736
Schedule of Interest Expense Recognized Related to Convertible Notes	The following table sets forth total interest expense recognized related to the Convertible Notes during the three and six months ended June 30, 2023 and 2022 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Amortization of debt issuance costs $ 74 $ 145 $ 147 $ 290 Contractual interest expense 822 1,680 1,643 3,360 Total interest expense $ 896 $ 1,825 $ 1,790 $ 3,650
Schedule of Future Minimum Payments on Convertible Notes Payable	Future minimum payments on Convertible Notes payable as of June 30, 2023 are as follows (in thousands): 2023 $ 1,644 2024 3,286 2025 3,286 2026 96,225 Total future minimum payments 104,441 Less: interest ( 10,544 ) Less: debt discount and issuance costs, net ( 1,014 ) Less: current portion — Convertible senior notes $ 92,883

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Schedule of Additional Information Related to Operating Lease Assets and Liabilities	Additional information related to the operating lease assets and liabilities is as follows (in thousands): June 30, December 31, 2023 2022 Operating Lease Assets $ 16,726 $ 18,747 Operating Lease Liabilities $ 17,918 $ 19,977 Weighted Average Remaining Term in years 3.12 3.57 Weighted Average discount rate used to measure 7.21 % 7.26 %
Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to operating leases for the six months ended June 30 2023 and 2022 is as follows (in thousands): 2023 2022 Operating cash flows from operating leases $ 4,094 $ 3,532 Operating lease assets obtained in exchange for lease obligations $ — $ —
Maturities of Operating Lease Liabilities	The maturities of the Company’s operating lease liabilities as of June 30, 2023 are as follows (in thousands): 2023 3,528 2024 6,416 2025 5,253 2026 4,339 2027 and thereafter 556 Total future minimum lease payments 20,092 Less Imputed interest ( 2,174 ) Total operating lease liabilities $ 17,918

Other Comprehensive Income an_2

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income/(Loss), by Component	The following tables summarize the changes in accumulated other comprehensive income/(loss), by component for the six months ended June 30, 2023 and 2022 (in thousands): Unrealized Gains (Losses) from Marketable Securities Foreign Currency Translation Adjustment Unrealized Gains (Losses) from Pension Plan Total Accumulated Other Comprehensive Income (Loss) Balances, December 31, 2022 — $ ( 2,521 ) $ 1,646 $ ( 875 ) Net other comprehensive income (loss) — 100 — 100 Balances, March 31, 2023 — ( 2,421 ) 1,646 ( 775 ) Net other comprehensive loss — ( 21 ) — ( 21 ) Balances, June 30, 2023 — ( 2,442 ) 1,646 ( 796 ) Unrealized Gains (Losses) from Marketable Securities Foreign Currency Translation Adjustment Total Accumulated Other Comprehensive Income (Loss) Balances, December 31, 2021 $ 1 $ ( 2,091 ) $ ( 2,090 ) Net other comprehensive income (loss) ( 52 ) 83 31 Balances, March 31, 2022 ( 51 ) ( 2,008 ) ( 2,059 ) Net other comprehensive loss ( 766 ) ( 369 ) ( 1,135 ) Balances, June 30, 2022 ( 817 ) ( 2,377 ) ( 3,194 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value, Nonrecurring [Member]
Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized	The following table presents the fair value of financial instruments recorded originally at amortized cost or fair value and not remeasured on a recurring basis (in thousands): June 30, 2023 Balance Sheet Classification Type of Instrument Level 1 Level 2 Level 3 Total Financial Assets: Cash and cash equivalents: Money market funds $ 454,793 $ — $ — $ 454,793 Total Financial Assets $ 454,793 $ — $ — $ 454,793 December 31, 2022 Balance Sheet Classification Type of Instrument Level 1 Level 2 Level 3 Total Financial Assets: Cash and cash equivalents Money market funds $ 527,728 $ — $ — $ 527,728 Total Financial Assets $ 527,728 $ — $ — $ 527,728

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Summary of Shares Outstanding that were Excluded from Calculation of Diluted Net Loss Per Share	Convertible notes and shares outstanding presented below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, as their effect is anti-dilutive (in thousands): As of June 30, 2023 2022 Convertible notes 2,379 4,865 Common stock options 10,665 13,072 Restricted stock units 4,669 3,254 Total 17,713 21,191

Nature of Organization and Op_2

Nature of Organization and Operations - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 616,259	$ 551,801	$ 604,489
Accumulated deficit	$ (2,608,675)	$ (2,308,860)

Product Revenues, Accounts Re_3

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Revenue	$ 94,969	$ 16,322	$ 139,814	$ 30,703
Accounts receivable	110,913		110,913		$ 7,727
Accrued Expenses [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Product sales reserves	10,400		10,400		$ 2,400
Product Revenue, Net [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Revenue	$ 89,645	$ 15,654	$ 128,444	$ 27,763

Product Revenues, Accounts Re_4

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Disaggregation of Product Revenue by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 94,969	$ 16,322	$ 139,814	$ 30,703
EMPAVELI [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	22,303	15,654	42,742	27,763
SYFOVRE [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	67,342		85,702
Product Revenue, Net [Member]
Product Revenues Accounts Receivable And Reserves For Product Sales [Line Items]
Total Product revenue, net	$ 89,645	$ 15,654	$ 128,444	$ 27,763

Product Revenues, Accounts Re_5

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Summary of Product Revenue Allowance and Reserve Categories (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2023	Mar. 31, 2023
Chargebacks, Discounts, and Fees [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 1,446	$ 164
Provision related to sales in the current year	3,944	1,466
Adjustments related to prior period sales	(84)
Credits and payments made	(1,668)	(184)
Ending balance	3,638	1,446
Government and Other Rebates [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	2,861	1,936
Provision related to sales in the current year	5,114	2,566
Adjustments related to prior period sales	30	(2)
Credits and payments made	(2,946)	(1,639)
Ending balance	5,059	2,861
Returns [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	653	251
Provision related to sales in the current year	1,588	651
Adjustments related to prior period sales	(416)	(249)
Credits and payments made	(141)
Ending balance	1,684	653
Product Revenue Allowance and Reserves [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	4,960	2,351
Provision related to sales in the current year	10,646	4,683
Adjustments related to prior period sales	(470)	(251)
Credits and payments made	(4,755)	(1,823)
Ending balance	$ 10,381	$ 4,960

Product Revenues, Accounts Re_6

Product Revenues, Accounts Receivable, and Reserves for Product Sales - Schedule of Customer Accounted for 10% of More of Gross Product Revenues and Accounts Receivable (Detail) - Customer Concentration Risk [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Gross Product Revenues [Member] | Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk	24%	99%	33%	99%
Gross Product Revenues [Member] | Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk			12%
Gross Product Revenues [Member] | Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk	58%		50%
Accounts Receivable [Member] | Customer A [Member]
Revenue, Major Customer [Line Items]
Concentration risk				99%
Accounts Receivable [Member] | Customer C [Member]
Revenue, Major Customer [Line Items]
Concentration risk			16%
Accounts Receivable [Member] | Customer D [Member]
Revenue, Major Customer [Line Items]
Concentration risk			69%

Inventory - Schedule Of Invento

Inventory - Schedule Of Inventory Current (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Raw materials	$ 32,711	$ 29,847
Semi-finished goods	48,368	54,101
Finished goods	22,137	1,766
Total Inventories	$ 103,216	$ 85,714

Prepaid and Other Current Ass_3

Prepaid and Other Current Assets - Summary of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Prepaid Expense and Other Assets, Current [Abstract]
Down payments for inventory	$ 3,644	$ 13,987
Prepaid research and development	18,964	15,181
Other prepaid expenses	11,796	7,182
Total prepaid expenses	34,404	36,350
Royalties receivable	2,386	1,442
ERC credit		8,711
Receivable from collaboration agreement	15,000	20,000
Deposits and other current assets	9,423	6,505
Total other current assets	$ 26,809	$ 36,658

Development Liability - Additio

Development Liability - Additional Information (Detail) $ in Thousands			1 Months Ended						3 Months Ended		6 Months Ended
	Jan. 29, 2020 USD ($)	Feb. 28, 2019 USD ($) Installment	May 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	May 31, 2022 USD ($)	Jan. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) Installment	Jun. 30, 2021 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 07, 2019 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Interest expense									$ 7,341	$ 8,448	$ 14,869	$ 16,986
SFJ Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from SFJ agreement	$ 140,000	$ 60,000
Additional funding amount upon achievement of development milestones		$ 60,000
Number of milestone payments | Installment		3
Increase in additional funding for development costs													$ 20,000
Obligated to pay initial payment							$ 5,000		397,000		397,000
Aggregate amount of additional annual payments							$ 225,000
Number of additional annual payments | Installment							6
Payment made under agreement						$ 5,000		$ 4,000			63,000
First annual payment under agreement			$ 24,500	$ 18,000	$ 11,500
Interest expense									$ 6,500		$ 13,100
SFJ Agreement [Member] | Regulatory Approval Granted US Food and Drug Administration [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Obligated to pay initial payment		$ 4,000
Aggregate amount of additional annual payments		$ 226,000
Number of additional annual payments | Installment		6

Development Liability - Summary

Development Liability - Summary of Development Liability (Detail) - SFJ Agreement [Member] - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Development liability	$ 397,000	$ 421,500
Less: Unamortized discount to development liability	(63,271)	(76,349)
Less: Current portion of development liability, net of discount	(43,769)	(29,504)
Total long term development liability	$ 289,960	$ 315,647
Effective Interest Rate	7.91%	7.91%

Development Liability - Schedul

Development Liability - Schedule of Future Minimum SFJ Payments (Detail) - S F J Agreement [Member] - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
2023	$ 31,000
2024	98,750
2025	103,000
2026	109,000
2027 and thereafter	55,250
Total future minimum payments	$ 397,000	$ 5,000

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development	$ 31,240	$ 34,849
Accrued royalties	3,357	907
Accrued payroll liabilities	39,744	43,212
Other	23,375	16,171
Total accrued expenses	$ 97,716	$ 95,139

Long-term Debt - Additional Inf

Long-term Debt - Additional Information (Detail) $ in Thousands

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

May 12, 2020 USD ($)

Sep. 16, 2019 USD ($)

Jul. 31, 2022 USD ($) shares

Jul. 31, 2021 USD ($) shares

Jan. 31, 2021 USD ($) shares

Jun. 30, 2023 USD ($)

Sep. 30, 2022 USD ($) shares

Jun. 30, 2022 USD ($)

Sep. 30, 2021 USD ($) shares

Mar. 31, 2021 USD ($)

Jun. 30, 2023 USD ($)

Jun. 30, 2022 USD ($)

Dec. 31, 2021 USD ($)

Dec. 31, 2022 USD ($)

Debt Instrument [Line Items]

Debt interest expense

$ 896

$ 1,825

$ 1,790

$ 3,650

Long-term debt

92,883

$ 92,883

2019 Convertible Notes [Member]

Debt Instrument [Line Items]

Premium paid for capped call transactions

$ 28,400

2020 Convertible Notes [Member]

Debt Instrument [Line Items]

Additional amount issued in payment of issuance costs

$ 2,500

Premium paid for capped call transactions

$ 43,100

2020 Convertible Notes [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Additional shares issued | shares

541,470

Convertible Senior Notes Due 2026 [Member]

Debt Instrument [Line Items]

Debt instrument, stated percentage

3.50%

Debt instrument, due and payment description

The Convertible Notes are senior unsecured obligations of the Company and bear interest at a rate of 3.5% per year payable semiannually in arrears on March 15 and September 15 of each year, beginning on March 15, 2020.

Debt instrument, frequency of periodic payment

semiannually

Maturity date

Sep. 15, 2026

Redemption price, percentage

100%

Long-term debt

92,883

$ 92,883

$ 92,736

Convertible Senior Notes Due 2026 [Member] | 2019 Convertible Notes [Member]

Debt Instrument [Line Items]

Net proceeds from the sale of the notes

$ 212,900

Payment of convertible debt discounts and commissions

6,600

Payment of convertible debt offering expenses

500

Payments of transactions cost

28,400

Convertible Senior Notes Due 2026 [Member] | 2019 Convertible Notes [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Conversion ratio

0.0253405

0.0253405

Debt issuance costs

$ 4,100

$ 3,300

Increase (decrease) in net debt

$ 197,000

122,800

Aggregate principal amount converted

$ 126,100

Increase in shares outstanding | shares

5,992,217

3,906,869

Shares issued | shares

5,097,166

3,196,172

Additional shares issued | shares

895,051

710,697

Additional shares issued for settlement of debt issuance cost paid | shares

78,419

69,491

78,419

Loss on conversion of debt

$ 61,100

$ 39,500

Loss on conversion of debt related to additional shares issued

55,900

36,400

Additional amount issued in payment of issuance costs

$ 5,200

$ 3,100

Forfeiture of accrued interest in exchange of convertible notes

$ 1,700

Convertible Senior Notes Due 2026 [Member] | 2019 Convertible Notes [Member] | Common Stock [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Aggregate principal amount converted into shares | shares

3,906,869

Convertible Senior Notes Due 2026 [Member] | 2020 Convertible Notes [Member]

Debt Instrument [Line Items]

Net proceeds from the sale of the notes

$ 322,900

Payment of convertible debt discounts and commissions

5,700

Payment of convertible debt offering expenses

300

Payments of transactions cost

43,100

Convertible Senior Notes Due 2026 [Member] | 2020 Convertible Notes [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Conversion ratio

0.0253405

Debt issuance costs

$ 1,300

Increase (decrease) in net debt

96,800

Aggregate principal amount converted

$ 98,100

Convertible notes held in treasury

$ 425,400

$ 425,400

Shares issued | shares

2,485,548

Additional shares issued for settlement of debt issuance cost paid | shares

46,132

46,132

Loss on conversion of debt

$ 32,900

Loss on conversion of debt related to additional shares issued

$ 30,400

Convertible Senior Notes Due 2026 [Member] | 2020 Convertible Notes [Member] | Common Stock [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Aggregate principal amount converted into shares | shares

3,027,018

5,992,217

Convertible Senior Notes Due 2026 [Member] | 2019 and 2020 Convertible Notes [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Aggregate principal amount converted

$ 201,100

Forfeiture of accrued interest in exchange of convertible notes

$ 2,500

Convertible Senior Notes Due 2026 [Member] | Convertible Senior Notes [Member] | Exchange Agreements [Member]

Debt Instrument [Line Items]

Increase in shares outstanding | shares

3,027,018

Convertible Senior Notes Due 2026 [Member] | Private Offering [Member] | 2019 Convertible Notes [Member]

Debt Instrument [Line Items]

Principal amount

$ 220,000

Convertible Senior Notes Due 2026 [Member] | Private Offering [Member] | 2020 Convertible Notes [Member]

Debt Instrument [Line Items]

Principal amount

$ 300,000

Long-term Debt - Schedule of Ou

Long-term Debt - Schedule of Outstanding Balance of Convertible Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Principal	$ 104,441
Less: debit discount and issuance costs, net	(1,014)
Net carrying amount	92,883
Convertible Senior Notes Due 2026 [Member]
Debt Instrument [Line Items]
Principal	93,897	$ 93,897
Less: debit discount and issuance costs, net	(1,014)	(1,161)
Net carrying amount	$ 92,883	$ 92,736

Long-term Debt - Schedule of In

Long-term Debt - Schedule of Interest Expense Recognized Related to Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 74	$ 145	$ 147	$ 290
Contractual interest expense	822	1,680	1,643	3,360
Total interest expense	$ 896	$ 1,825	$ 1,790	$ 3,650

Long-term Debt - Schedule of Fu

Long-term Debt - Schedule of Future Minimum Payments on Convertible Notes Payable (Details) $ in Thousands	Jun. 30, 2023 USD ($)
Schedule of Long-Term Debt Instruments [Table]
2023	$ 1,644
2024	3,286
2025	3,286
2026	96,225
Total future minimum payments	104,441
Less: interest	(10,544)
Less: debit discount and issuance costs, net	(1,014)
Net carrying amount	$ 92,883

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lessee Lease Description [Line Items]
Operating lease description			The Company enters into lease agreements with terms generally ranging from 2-7 years. Some of the Company’s lease agreements include Company options to extend the lease on a month-to-month basis or for set periods for up to five years. Many of these leases also include options to terminate the leases within one year or per other contractual terms. Renewal and termination options were generally not included in the lease term for the Company’s existing operating leases.
Operating lease, existence of option to extend			true
Operating lease maximum term of options to terminate lease			1 year
Operating lease expense	$ 1.7	$ 1.5	$ 3.4	$ 2.9
Minimum [Member]
Lessee Lease Description [Line Items]
Operating lease, term of contract	2 years		2 years
Maximum [Member]
Lessee Lease Description [Line Items]
Operating lease, term of contract	7 years		7 years
Operating lease options to extend lease	5 years		5 years

Leases - Schedule of Additional

Leases - Schedule of Additional Information Related to Operating Lease Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Leases [Abstract]
Operating Lease Assets	$ 16,726	$ 18,747
Operating Lease Liabilities	$ 17,918	$ 19,977
Weighted Average Remaining Term in years	3 years 1 month 13 days	3 years 6 months 25 days
Weighted Average discount rate used to measure outstanding lease liabilities	7.21%	7.26%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information Related to Operating Leases (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Leases [Abstract]
Operating cash flows from operating leases	$ 4,094	$ 3,532

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Leases [Abstract]
2023	$ 3,528
2024	6,416
2025	5,253
2026	4,339
2027 and thereafter	556
Total future minimum lease payments	20,092
Less Imputed interest	(2,174)
Total operating lease liabilities	$ 17,918	$ 19,977

Other Comprehensive Income an_3

Other Comprehensive Income and Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income/(Loss), by Component (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 412,123	$ 169,872	$ 462,235	$ 198,662
Ending balance	345,403	412,123	(334,418)	462,235
Unrealized Gains (Losses) from Marketable Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance			(51)	1
Net other comprehensive income (loss)			(766)	(52)
Ending balance			(817)	(51)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(2,421)	(2,521)	(2,008)	(2,091)
Net other comprehensive income (loss)	(21)	100	(369)	83
Ending balance	(2,442)	(2,421)	(2,377)	(2,008)
Unrealized Gains (Losses) from Pension Plan
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	1,646	1,646
Ending balance	1,646	1,646
Total Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(775)	(875)	(2,059)	(2,090)
Net other comprehensive income (loss)	(21)	100	(1,135)	31
Ending balance	$ (796)	$ (775)	$ (3,194)	$ (2,059)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Instruments and the Related Fair Value Hierarchy of the Valuation Techniques Utilized (Detail) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 454,793	$ 527,728
Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	454,793	527,728
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	454,793	527,728
Level 1 [Member] | Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Financial Assets	$ 454,793	$ 527,728

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Level 1 [Member] | Convertible Senior Notes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible notes	$ 218.9	$ 143.9
Convertible notes, interest rate	3.50%	3.50%
Level 2 [Member] | Development Liability [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value		$ 315.8	$ 317

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income tax expense	$ 194,000	$ 486,000	$ 476,000	$ 1,694,000
U.S. federal statutory rate			21%
Minimum percentage of tax position likelihood of being realized upon examination by taxing authorities			50%
Unrecognized tax benefits	$ 0		$ 0

License and Collaboration Agr_2

License and Collaboration Agreements - Additional Information (Detail)

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

Nov. 30, 2020 USD ($)

Oct. 27, 2020 USD ($)

Apr. 30, 2023 USD ($)

Jan. 31, 2023 USD ($)

Jun. 30, 2022 USD ($)

Apr. 30, 2022 USD ($)

Jan. 31, 2022 USD ($)

Aug. 31, 2021 USD ($)

Jun. 30, 2021 Program

Jan. 31, 2021 USD ($)

Jun. 30, 2023 USD ($) License

Jun. 30, 2022 USD ($)

Jun. 30, 2023 USD ($) License

Jun. 30, 2022 USD ($)

Dec. 31, 2020 USD ($)

Dec. 31, 2022 USD ($)

Jul. 31, 2021 USD ($)

Oct. 31, 2020 USD ($)

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Revenue

$ 94,969,000

$ 16,322,000

$ 139,814,000

$ 30,703,000

EMPAVELI [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Revenue

22,303,000

15,654,000

42,742,000

27,763,000

SYFOVRE [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Revenue

67,342,000

$ 85,702,000

Regulatory milestone payments

$ 2,300,000

Swedish Orphan Biovitrum AB (Publ) [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Development cost reimbursement

$ 80,000,000

Non-refundable Upfront Payment

250,000,000

Collaboration and License Agreement [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Development cost reimbursement

$ 80,000,000

Collaboration and License Agreement [Member] | License [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment

$ 250,000,000

Collaboration and License Agreement [Member] | Swedish Orphan Biovitrum AB (Publ) [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment

$ 250,000,000

Milestone payment received for achievement of regulatory development milestone

$ 50,000,000

Development cost reimbursement

$ 80,000,000

Development cost reimbursement received

$ 20,000,000

$ 20,000,000

25,000,000

Royalties entitled to receive after first commercial sale of applicable licensed product period

10 years

Royalty revenue

2,400,000

700,000

$ 4,000,000

800,000

Contract research and development reimbursement commitment

80,000,000

Contract research and development expense

0

0

0

5,000,000

Contract research and development receivable

$ 35,000,000

Contract research and development receivable other current assets

20,000,000

Contract research and development current

15,000,000

15,000,000

Contract research and development receivable other assets

$ 15,000,000

Proceeds from contract research and development

20,000,000

Collaboration and License Agreement [Member] | Swedish Orphan Biovitrum AB (Publ) [Member] | ASC Topic 808

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Upfront payment

$ 250,000,000

Development cost reimbursement

80,000,000

Collaboration and License Agreement [Member] | Swedish Orphan Biovitrum AB (Publ) [Member] | Maximum [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Aggregate milestone payments upon achievement of specified one time regulatory development and commercial milestone events

$ 915,000,000

Collaboration and License Agreement [Member] | Swedish Orphan Biovitrum AB (Publ) [Member] | Maximum [Member] | ASC Topic 808

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Aggregate milestone payments upon achievement of specified one-time regulatory and commercial milestone events

$ 915,000,000

University of Pennsylvania [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Annual maintenance fees

100,000

Development milestone achievement

$ 5,000,000

$ 1,000,000

University of Pennsylvania [Member] | EMPAVELI [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Milestone payments based on annual sales milestones

$ 1,000,000

University of Pennsylvania [Member] | Maximum [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Aggregate milestones payments

$ 3,200,000

3,200,000

Milestone payments based on annual sales milestones

5,000,000

2010 License Agreement [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Annual maintenance fees

$ 100,000

Number of licensed products | License

2

2

2010 License Agreement [Member] | Maximum [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Aggregate milestones payments

$ 1,700,000

$ 1,700,000

Milestone payments based on annual sales milestones

$ 2,500,000

Sobi Agreement and Another Licensing Transaction [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Sublicense fee owed

$ 25,000,000

Research Collaboration Agreement [Member] | Beam [Member]

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Collaboration agreement term

5 years

Number of research programs | Program

6

Up-front non-refundable payment

$ 50,000,000

Up-front payment on first anniversary of agreement on June 30, 2022

$ 25,000,000

$ 25,000,000

$ 25,000,000

Collaboration agreement maximum extendable term

2 years

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2023 USD ($)
Commitments And Contingencies [Line Items]
Incurred any cost to defend lawsuits or settle claims	$ 0
Vehicles [Member]
Commitments And Contingencies [Line Items]
Operating lease, term of contract	36 months
Bachem Americas, Inc [Member]
Commitments And Contingencies [Line Items]
Non-cancellable purchase obligation substance over period	5 years
Non-cancellable purchase commitments	$ 147,200,000
Other Commitment	$ 21,700,000

Net Loss per Share - Summary of

Net Loss per Share - Summary of Shares Outstanding that were Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	17,713	21,191
Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,379	4,865
Common Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	10,665	13,072
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	4,669	3,254