FibroGen (FGEN) 10-Q 6 Aug 24 2024 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 31, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN, INC.
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-36740
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0357827
Entity Address, Address Line One	409 Illinois Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	978-1200
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock Shares Outstanding		100,400,786

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 140,714,000	$ 113,688,000
Short-term investments	0	121,898,000
Accounts receivable, net ($4,178 and $6,079 from related parties)	6,412,000	12,553,000
Inventories	25,397,000	41,565,000
Prepaid expenses and other current assets	36,936,000	41,855,000
Total current assets	209,459,000	331,559,000
Restricted time deposits	1,658,000	1,658,000
Property and equipment, net	10,917,000	13,126,000
Equity method investment in unconsolidated variable interest entity	6,912,000	5,290,000
Operating lease right-of-use assets	61,212,000	68,093,000
Other assets	3,045,000	3,803,000
Total assets	293,203,000	423,529,000
Current liabilities:
Accounts payable ($1,586 and $0 to a related party)	9,938,000	17,960,000
Accrued and other current liabilities ($10,993 and $39,814 to a related party)	113,574,000	172,891,000
Deferred revenue ($6,111 and $7,220 to related parties)	9,546,000	12,740,000
Operating lease liabilities, current	15,531,000	14,077,000
Total current liabilities	148,589,000	217,668,000
Product development obligations	17,397,000	17,763,000
Deferred revenue, net of current ($3,292 and $9,705 to a related party)	131,192,000	157,555,000
Operating lease liabilities, non-current	58,376,000	66,537,000
Senior secured term loan facilities, non-current	72,478,000	71,934,000
Liability related to sale of future revenues, non-current	54,532,000	51,413,000
Other long-term liabilities ($605 and $656 to a related party)	1,012,000	2,858,000
Total liabilities	483,576,000	585,728,000
Commitments and Contingencies (Note 12)
Redeemable non-controlling interests	21,480,000	21,480,000
Stockholders' deficit:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at June 30, 2024 and December 31, 2023
Common stock, $0.01 par value; 225,000 shares authorized at June 30, 2024 and December 31, 2023; 100,400 and 98,770 shares issued and outstanding at June 30, 2024 and December 31, 2023	1,004,000	988,000
Additional paid-in capital	1,660,862,000	1,643,641,000
Accumulated other comprehensive loss	(3,809,000)	(6,875,000)
Accumulated deficit	(1,890,397,000)	(1,841,920,000)
Total stockholders' deficit attributable to FibroGen	(232,340,000)	(204,166,000)
Nonredeemable non-controlling interests	20,487,000	20,487,000
Total deficit	(211,853,000)	(183,679,000)
Total liabilities, redeemable non-controlling interests and deficit	$ 293,203,000	$ 423,529,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Accounts receivable from related parties	$ 4,178	$ 6,079
Accounts payable to related party	1,586	0
Accrued and other current liabilities to related party	10,993	39,814
Deferred revenue current to related party	6,111	7,220
Deferred revenue non-current to related party	3,292	9,705
Due to related parties, noncurrent	$ 605	$ 656
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	125,000,000	125,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	100,400,000	98,770,000
Common stock, shares outstanding	100,400,000	98,770,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue:
Total revenue	$ 50,641	$ 44,319	$ 106,544	$ 80,480
Operating costs and expenses:
Cost of goods sold	$ 5,178	$ 5,708	$ 30,931	$ 9,199
Cost, Product and Service [Extensible List]	Product Revenue, Net [Member]	Product Revenue, Net [Member]	Product Revenue, Net [Member]	Product Revenue, Net [Member]
Research and development	$ 34,106	$ 95,478	$ 72,498	$ 169,964
Selling, general and administrative	22,276	31,181	45,097	65,455
Total operating costs and expenses	61,560	132,367	148,526	244,618
Loss from operations	(10,919)	(88,048)	(41,982)	(164,138)
Interest and other, net
Interest expense	(4,783)	(3,069)	(9,779)	(5,441)
Interest income and other income (expenses), net	(1,281)	2,652	1,289	3,687
Total interest and other, net	(6,064)	(417)	(8,490)	(1,754)
Loss before income taxes	(16,983)	(88,465)	(50,472)	(165,892)
Benefit from income taxes	(262)	(235)	(229)	(161)
Investment income in unconsolidated variable interest entity	1,177	550	1,766	1,346
Net loss	$ (15,544)	$ (87,680)	$ (48,477)	$ (164,385)
Net loss per share - basic	$ (0.16)	$ (0.9)	$ (0.49)	$ (1.71)
Net loss per share - diluted	$ (0.16)	$ (0.9)	$ (0.49)	$ (1.71)
Weighted average number of common shares used to calculate net loss per share:
Basic	99,835	97,729	99,408	96,218
Diluted	99,835	97,729	99,408	96,218
License Revenue [Member]
Revenue:
Total revenue	$ 0	$ 1,000	$ 0	$ 7,000
Development and Other Revenue [Member]
Revenue:
Total revenue	269	5,158	1,147	9,050
Product Revenue, Net [Member]
Revenue:
Total revenue	49,643	23,889	80,181	48,049
Drug Product Revenue, Net [Member]
Revenue:
Total revenue	$ 729	$ 14,272	$ 25,216	$ 16,381

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Collaboration services and other revenue from a related party	$ 319	$ 1,839	$ 613	$ 3,463
Product revenue from a related party	46,005	20,512	73,118	41,884
Drug product revenue from a related party	$ 729	$ 14,272	$ (455)	$ 16,381

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net loss	$ (15,544)	$ (87,680)	$ (48,477)	$ (164,385)
Other comprehensive income (loss):
Foreign currency translation adjustments	2,700	(2,337)	3,092	(2,585)
Available-for-sale investments:
Unrealized gain (loss) on investments, net of tax effect	(2)	657	(26)	2,055
Other comprehensive gain (loss), net of taxes	2,698	(1,680)	3,066	(530)
Comprehensive loss	$ (12,846)	$ (89,360)	$ (45,411)	$ (164,915)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Noncontrolling Interests [Member] Nonredeemable [Member]	Noncontrolling Interests [Member] Redeemable [Member]
Balance at Dec. 31, 2022	$ (1,480)	$ 942	$ 1,541,019	$ (5,720)	$ (1,557,688)	$ 19,967	$ 0
Balance, Shares at Dec. 31, 2022		94,166,086
Net loss	$ (164,385)	$ 0	$ 0	$ 0	$ (164,385)	$ 0	$ 0
Consolidation of Fortis (Note 4)	520,000	0	0	0	0	520,000	21,480,000
Change in unrealized gain or loss on investments	$ 2,055	$ 0	$ 0	$ 2,055	$ 0	$ 0	$ 0
Foreign currency translation adjustments	(2,585)	0	0	(2,585)	0	0	0
Issuance of common stock under ATM Program	48,407	$ 24	48,383	0	0	0	0
Issuance of common stock under ATM Program shares		2,472,090
Shares issued from stock plans, net of payroll taxes paid	3,686	$ 16	3,670	0	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,566,067
Stock-based compensation	31,995	$ 0	31,995	0	0	0	0
Balance at Jun. 30, 2023	(81,787)	$ 982	1,625,067	(6,250)	(1,722,073)	20,487	21,480
Balance, Shares at Jun. 30, 2023		98,204,243
Balance at Mar. 31, 2023	(28,885)	$ 966	1,589,145	(4,570)	(1,634,393)	19,967	0
Balance, Shares at Mar. 31, 2023		96,623,309
Net loss	$ (87,680)	$ 0	0	0	(87,680)	$ 0	$ 0
Consolidation of Fortis (Note 4)	520,000					520,000	21,480,000
Change in unrealized gain or loss on investments	$ 657	0	0	657	0	$ 0	$ 0
Foreign currency translation adjustments	(2,337)	0	0	(2,337)	0	0	0
Issuance of common stock under ATM Program	17,276	$ 9	17,267	0	0	0	0
Issuance of common stock under ATM Program shares		930,511
Shares issued from stock plans, net of payroll taxes paid	2,779	$ 7	2,772	0	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		650,423
Stock-based compensation	15,883	$ 0	15,883	0	0	0	0
Balance at Jun. 30, 2023	(81,787)	$ 982	1,625,067	(6,250)	(1,722,073)	20,487	21,480
Balance, Shares at Jun. 30, 2023		98,204,243
Balance at Dec. 31, 2023	(183,679)	$ 988	1,643,641	(6,875)	(1,841,920)	20,487	21,480
Balance, Shares at Dec. 31, 2023		98,770,247
Net loss	(48,477)	$ 0	0	0	(48,477)	0	0
Change in unrealized gain or loss on investments	(26)	0	0	(26)	0	0	0
Foreign currency translation adjustments	3,092	0	0	3,092	0	0	0
Shares issued from stock plans, net of payroll taxes paid	(113)	$ 16	(129)	0	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,629,539
Stock-based compensation	17,350	$ 0	17,350	0	0	0	0
Balance at Jun. 30, 2024	(211,853)	$ 1,004	1,660,862	(3,809)	(1,890,397)	20,487	21,480
Balance, Shares at Jun. 30, 2024		100,399,786
Balance at Mar. 31, 2024	(207,635)	$ 995	1,652,243	(6,507)	(1,874,853)	20,487	21,480
Balance, Shares at Mar. 31, 2024		99,474,398
Net loss	(15,544)	$ 0	0	0	(15,544)	0	0
Change in unrealized gain or loss on investments	(2)	0	0	(2)	0	0	0
Foreign currency translation adjustments	2,700	0	0	2,700	0	0	0
Shares issued from stock plans, net of payroll taxes paid	40	$ 9	31	0	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		925,388
Stock-based compensation	8,588	$ 0	8,588	0	0	0	0
Balance at Jun. 30, 2024	$ (211,853)	$ 1,004	$ 1,660,862	$ (3,809)	$ (1,890,397)	$ 20,487	$ 21,480
Balance, Shares at Jun. 30, 2024		100,399,786

Condensed Consolidated Statem_5

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Operating activities
Net loss	$ (48,477)	$ (164,385)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,582	5,020
Amortization of finance lease right-of-use assets	19	657
Net accretion of premium and discount on investments	(1,681)	(1,815)
Investment income in unconsolidated variable interest entity	(1,766)	(1,346)
Loss on disposal of property and equipment	306	1
Stock-based compensation	17,350	31,995
Acquired in-process research and development expenses	0	24,636
Non-cash interest expense related to sale of future revenues	0	3,577
Impairment of investment	0	1,000
Realized loss on sales of available-for-sale securities	0	271
Changes in operating assets and liabilities:
Accounts receivable, net	5,962	(10,007)
Inventories	15,578	(1,951)
Prepaid expenses and other current assets	4,527	4,199
Operating lease right-of-use assets	6,806	5,296
Other assets	441	99
Accounts payable	(7,977)	(20,784)
Accrued and other liabilities	(52,663)	(57,016)
Operating lease liabilities, current	1,489	787
Deferred revenue	(29,501)	(25,555)
Accrued interest expense related to sale of future revenues	(1,904)	0
Accrued interest for finance lease liabilities	12	68
Operating lease liabilities, non-current	(8,128)	(5,666)
Other long-term liabilities	(1,132)	(1,243)
Net cash used in operating activities	(99,157)	(212,162)
Investing activities
Purchases of property and equipment	(43)	(1,584)
Proceeds from sale of property and equipment	3	0
Purchases of available-for-sale securities	(8,628)	(104,543)
Cash acquired from consolidation of Fortis	0	656
Proceeds from sales of available-for-sale securities	0	1,730
Proceeds from maturities of investments	132,183	192,938
Net cash provided by investing activities	123,515	89,197
Financing activities
Proceeds from senior secured term loan facilities, net of issuance costs	0	74,078
Cash paid for transaction costs for senior secured term loan facilities	0	(2,746)
Repayments of finance lease liabilities	(20)	(207)
Repayments of lease obligations	0	(201)
Cash paid for payroll taxes on restricted stock unit releases	(229)	0
Proceeds from issuance of common stock under ATM Program, net of commissions	0	48,407
Proceeds from issuance of common stock under employee stock plans	116	3,686
Net cash provided by (used in) financing activities	(133)	123,017
Effect of exchange rate change on cash and cash equivalents	2,801	(3,167)
Net increase (decrease) in cash and cash equivalents	27,026	(3,115)
Total cash and cash equivalents at beginning of period	113,688	155,700
Total cash and cash equivalents at end of period	$ 140,714	$ 152,585

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (15,544)	$ (87,680)	$ (48,477)	$ (164,385)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Rule 10b5-1 Trading Arrangements None.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Significant Accounting Policies	1. Significant Accounting Policies Description of Operations FibroGen, Inc. (“FibroGen” or the “Company”) is headquartered in San Francisco, California, with subsidiary offices in Beijing and Shanghai, People’s Republic of China (“China”). FibroGen is developing and commercializing a diversified pipeline of novel therapeutics that work at the frontier of cancer biology and anemia. Roxadustat is an oral small molecule inhibitor of hypoxia-inducible factor prolyl hydroxylase activity. Roxadustat (爱瑞卓 ® , EVRENZO TM ) is approved in China, Europe, Japan, and numerous other countries for the treatment of anemia in chronic kidney disease for patients who are on dialysis and not on dialysis. Roxadustat is in clinical development for chemotherapy-induced anemia in China. FG-3246 is a first-in-class antibody-drug conjugate targeting a novel epitope on CD46 that is in development for metastatic castration-resistant prostate cancer and other cancer indications. FibroGen also has a pipeline of preclinical product candidates, FG-3165 and FG-3175, to address unmet patient needs in oncology. Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements include the accounts of FibroGen, its wholly-owned subsidiaries and its majority-owned subsidiaries, as well as any variable interest entity (“VIE”) for which FibroGen is the primary beneficiary. All inter-company transactions and balances have been eliminated in consolidation. For any VIE for which FibroGen is not the primary beneficiary, the Company uses the equity method of accounting. The Company operates as one reportable segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs. The unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) applicable to interim financial reporting and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the United States (“U.S.”) Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and footnote disclosures normally included in the annual consolidated financial statements. The financial information included herein should be read in conjunction with the consolidated financial statements and related notes in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed on February 26, 2024. Based on its current operating plan, which contemplates the maintenance of a minimum balance of $ 30 million of unrestricted cash and cash equivalents held in accounts in the U.S., as required under the debt covenants associated with the senior secured term loan facilities, the Company believes that its existing cash and cash equivalents and accounts receivable will be sufficient to meet its anticipated cash requirements for at least the next 12 months from the date of issuance of the financial statements. However, the Company may need additional capital to fund its operations and its liquidity assumptions may materially differ (including assumptions with respect to our research and development expenses, revenue expectations, contractual obligations, ability to repatriate cash from China, partnering or monetization of assets, and others). In addition, the Company may elect to raise additional funds at any time through equity, equity-linked, debt financing arrangements or from other sources. Use of Estimates The preparation of the condensed consolidated 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 at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include valuation and recognition of revenue and deferred revenue, specifically, estimates in variable consideration for drug product sales, and estimates in transaction price per unit for the China performance obligation. On an ongoing basis, management reviews these estimates and assumptions. Changes in facts and circumstances may alter such estimates and actual results could differ from those estimates. In the Company’s opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of its financial position, results of operations and cash flows for the interim periods presented. Significant Accounting Policies The accounting policies used by the Company in its presentation of interim financial results are consistent with those presented in Note 2 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed on February 26, 2024. Net Loss per Share Potential common shares that would have the effect of increasing diluted earnings per share are considered to be anti-dilutive and as such, these shares are not included in the calculation of diluted earnings per share. The Company reported a net loss for each of the three and six months ended June 30, 2024 and 2023. Therefore, dilutive common shares are not assumed to have been issued since their effect is anti-dilutive for these periods. Diluted weighted average shares excluded the following potential common shares related to s tock options, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), total shareholder return (“TSR”) awards and shares to be purchased under the 2014 Employee Stock Purchase Plan (“ESPP”) for the periods presented as they were anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Employee stock options 15,072 9,701 13,792 8,857 RSUs, PRSUs and TSR awards 3,899 3,084 3,922 3,078 ESPP 460 747 496 554 19,431 13,532 18,210 12,489 Risks and Uncertainties The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, the results of clinical trials and the achievement of milestones, research developments, actions by regulatory authorities, market acceptance of the Company’s product candidates, competition from other products and larger companies, the liquidity and capital resources of the Company, intellectual property protection for the Company’s proprietary technology, strategic relationships, and dependence on key individuals, suppliers, clinical organization, and other third parties. Recently Issued Accounting Guidance Not Yet Adopted In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires all public entities, including public entities with a single reportable segment, to provide in interim and annual periods one or more measures of segment profit or loss used by the chief operating decision maker to allocate resources and assess performance. In addition, this guidance requires disclosures of significant segment expenses and other segment items as well as incremental qualitative disclosures. This guidance is effective for fiscal years beginning after December 15, 2023, and interim periods after December 15, 2024, with retrospective application required, and early adoption permitted. The Company is currently in the process of evaluating the effects of this guidance on its related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which requires enhanced income tax disclosures, including specific categories and disaggregation of information in the effective tax rate reconciliation, disaggregated information related to income taxes paid, income or loss from continuing operations before income tax expense or benefit, and income tax expense or benefit from continuing operations. This guidance is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently in the process of evaluating the impact of this pronouncement on its related disclosures.

Collaboration Agreements, Licen

Collaboration Agreements, License Agreement and Revenues	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration Agreements, License Agreement and Revenues	2. Collaboration Agreements, License Agreement and Revenues Astellas Agreements Astellas Japan Agreement In June 2005, the Company entered into a collaboration agreement with Astellas Pharma Inc. (“Astellas”) for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in Japan (“Astellas Japan Agreement”). Under this agreement, Astellas agreed to pay license fees, other upfront consideration and various milestone payments, totaling $ 172.6 million . The Astellas Japan Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range of the list price published by Japan’s Ministry of Health, Labour and Welfare, adjusted for certain elements, after commercial launch. The aggregate amount of consideration received through June 30, 2024 totaled $ 105.1 million , excluding drug product revenue that is discussed under the Drug Product Revenue, Net section below. Based on its current development plans for roxadustat in Japan, the Company does not expect to receive most or all of the additional potential milestones under the Astellas Japan Agreement. Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were not material for the three and six months ended June 30, 2024 and 2023. The transaction price related to consideration received through June 30, 2024 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Japan Agreement (in thousands): Astellas Japan Agreement Total Consideration License $ 100,347 Development revenue 17,100 Total license and development revenue $ 117,447 There was no license revenue or development revenue resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods for the three months ended June 30, 2024 under the Astellas Japan Agreement. The Company does no t expect material variable consideration from estimated future co-development billing beyond the development period in the transaction price related to the Astellas Japan Agreement. In 2018, FibroGen and Astellas entered into an amendment to the Astellas Japan Agreement that allows Astellas to manufacture roxadustat drug product for commercialization in Japan (the “Astellas Japan Amendment”). The related drug product revenue is described under the Drug Product Revenue, Net section below. Astellas Europe Agreement In April 2006, the Company entered into a separate collaboration agreement with Astellas for the development and commercialization of roxadustat for the treatment of anemia in Europe, the Middle East, the Commonwealth of Independent States and South Africa (“Astellas Europe Agreement”). Under the terms of the Astellas Europe Agreement, Astellas agreed to pay license fees, other upfront consideration and various milestone payments, totaling $ 745.0 million . U nder the Astellas Europe Agreement, Astellas committed to fund 50 % of joint development costs for Europe and North America, and all territory-specific costs. The Astellas Europe Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range . The aggregate amount of consideration received under the Astellas Europe Agreement through June 30, 2024 totaled $ 685.0 million , excluding drug product revenue that is discussed under the Drug Product Revenue, Net section below. Based on its current development plans for roxadustat in Europe, the Company does not expect to receive most or all of the additional potential milestones under the Astellas Europe Agreement. Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 Astellas Europe Agreement Development revenue $ 318 $ 1,806 $ 606 $ 3,335 The transaction price related to consideration received through June 30, 2024 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Europe Agreement as follows (in thousands): Astellas Europe Agreement Total Consideration License $ 618,975 Development revenue 287,322 Total license and development revenue $ 906,297 There was no license revenue or development revenue resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods for three months ended June 30, 2024 under the Astellas Europe Agreement. The Company does not expect material variable consideration from estimated future co-development billing beyond the development period in the transaction price related to the Astellas Japan Agreement. In 2021, the Company entered into an EU Supply Agreement with Astellas under the Astellas Europe Agreement (“Astellas EU Supply Agreement”) to define general forecast, order, supply and payment terms for Astellas to purchase roxadustat bulk drug product from FibroGen in support of commercial supplies. The related drug product revenue is described under the Drug Product Revenue, Net section below. AstraZeneca Agreements AstraZeneca U.S./Rest of World (“RoW”) Agreement Effective July 30, 2013, the Company entered into a collaboration agreement with AstraZeneca AB (“AstraZeneca”) for the development and commercialization of roxadustat for the treatment of anemia in the U.S. and all other countries in the world, other than China, not previously licensed under the Astellas Europe and Astellas Japan Agreements (“AstraZeneca U.S./RoW Agreement”). On February 23, 2024, the Company and AstraZeneca entered into an agreement to terminate the AstraZeneca U.S./RoW Agreement, effective as of February 25, 2024 (“AstraZeneca Termination and Transition Agreement). Pursuant to the AstraZeneca Termination and Transition Agreement, AstraZeneca returns all of their non-China roxadustat rights to the Company, with the exception of South Korea, and provides certain assistance during a transition period. In addition, as a part of this AstraZeneca Termination and Transition Agreement, AstraZeneca will receive tiered mid-single digit royalties on FibroGen’s sales of roxadustat in the terminated territories, or thirty-five percent of all revenue FibroGen receives if it licenses or sells such rights to a third-party. Neither party incurred any early termination penalties. The aggregate amount of consideration for milestone and upfront payments received under the AstraZeneca U.S./RoW Agreement through the termination totaled $ 439.0 million , excluding drug product revenue under the Master Supply Agreement with AstraZeneca under the AstraZeneca U.S./RoW Agreement (“AstraZeneca Master Supply Agreement”), entered in 2020, which is described under the Drug Product Revenue, Net section below. In addition, resulting from the AstraZeneca Termination and Transition Agreement, the Company and AstraZeneca settled the outstanding balances relating to past transactions under the AstraZeneca Master Supply Agreement. Accordingly, during the three months ended March 31, 2024, the Company accounted for the termination of the AstraZeneca U.S./RoW agreement as a contract modification under the Accounting Standards Codification (“ASC”) 606, Revenue from Contracts with Customers (“ASC 606”) and recorded a cumulative catch-up adjustment as described under the Drug Product Revenue, Net section below. The Company’s collaboration agreement with AstraZeneca for roxadustat in China, as described below, remains in place. AstraZeneca China Agreement Effective July 30, 2013, the Company (through its subsidiaries affiliated with China) entered into a collaboration agreement with AstraZeneca for roxadustat for the treatment of anemia in China (“AstraZeneca China Agreement”). Under the terms of the AstraZeneca China Agreement, AstraZeneca agreed to pay upfront consideration and potential milestone payments, totaling $ 376.7 million . The AstraZeneca China Agreement is structured as a 50/50 profit or loss share (as defined), which was amended under the AstraZeneca China Amendment in 2020 as discussed below, and provides for joint development costs (including capital and equipment costs for construction of the manufacturing plant in China), to be shared equally during the development period. The aggregate amount of such consideration received for milestone and upfront payments through June 30, 2024 totaled $ 77.2 million . On September 18, 2023, the Company received the formal notice, from Beijing Medical Products Administration, of renewal of its right to continue to market roxadustat in China through 2028. The Company evaluated the regulatory milestone payment associated with this renewal under the AstraZeneca China Agreement and concluded that this milestone was achieved in the third quarter of 2023. Accordingly, the consideration of $ 4.0 million associated with this milestone was included in the transaction price in the third quarter of 2023 and allocated to performance obligations under the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement. A s of June 30, 2024, t he $ 4.0 million milestone was recorded as a contract asset and was fully netted against the contract liabilities (deferred revenue) related to the AstraZeneca China Agreement. AstraZeneca China Amendment In July 2020, FibroGen China Anemia Holdings, Ltd., FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), FibroGen International (Hong Kong) Limited, and AstraZeneca entered into an amendment to the AstraZeneca China Agreement, relating to the development and commercialization of roxadustat in China (the “AstraZeneca China Amendment”). Under the AstraZeneca China Amendment, in 2020, FibroGen Beijing and AstraZeneca completed the establishment of a jointly owned entity, Beijing Falikang Pharmaceutical Co., Ltd. (“Falikang”), which performs roxadustat distribution, as well as conducts sales and marketing through AstraZeneca. Substantially all direct roxadustat product sales to distributors in China are made by Falikang, while FibroGen Beijing continues to sell roxadustat product directly in one province in China. FibroGen Beijing manufactures and supplies commercial product to Falikang based on a gross transfer price, which is adjusted for the estimated profit share. The net product revenue from the sales to Falikang and the net product revenue from direct sales distributors in China are described under Product Revenue, Net section below. Prior to the above-mentioned termination of the AstraZeneca U.S./RoW Agreement, the Company evaluated under the ASC 606 and accounted for the AstraZeneca U.S./RoW Agreement and the AstraZeneca China Agreement as a single arrangement with the presumption that two or more agreements executed with a single customer at or around the same time should be presumed to be a single arrangement. As a result of the termination of the AstraZeneca U.S./RoW Agreement, during the three months ended March 31, 2024, the Company recorded the final development revenue under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement. Amounts recognized as license revenue and development revenue under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement Development revenue $ ( 50 ) $ 2,273 $ 418 $ 4,305 The transaction price relat ed to consideration received and accounts receivable through the termination of the AstraZeneca U.S./RoW Agreement has been allocated to each of the performance obligations under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, including $ 344.5 million for license, $ 625.5 million for co-development, information sharing and committee services, and $ 427.5 million for China performance obligation (with cumulative revenue of $ 268.9 million through June 30, 2024) that is recognized as product revenue, as described under Product Revenue, Net section below. There was no license revenue or development revenue resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods for the three months ended June 30, 2024 under the AstraZeneca U.S./RoW Agreement through the agreement termination. Product Revenue, Net Product revenue, net from the sales of roxadustat commercial product in China was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Direct Sales: Gross revenue $ 4,046 $ 3,607 $ 7,831 $ 6,667 Discounts and rebates ( 408 ) ( 229 ) ( 767 ) ( 503 ) Sales returns — ( 1 ) ( 1 ) 1 Direct sales revenue, net 3,638 3,377 7,063 6,165 Sales to Falikang: Gross transaction price 49,352 42,153 92,912 76,402 Profit share ( 21,397 ) ( 18,312 ) ( 40,420 ) ( 33,300 ) Net transaction price 27,955 23,841 52,492 43,102 Decrease (increase) in deferred revenue 18,050 ( 3,329 ) 20,626 ( 1,218 ) Sales to Falikang revenue, net 46,005 20,512 73,118 41,884 Total product revenue, net $ 49,643 $ 23,889 $ 80,181 $ 48,049 Direct Sales Product revenue from direct roxadustat product sales to distributors in China is recognized in an amount that reflects the consideration that the Company expects to be entitled to in exchange for those products, net of various sales rebates and discounts. The total discounts and rebates were immaterial for the periods presented. Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts are presented as reductions to gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The Company’s legal right to offset is determined at the individual distributor level. The contract liabilities were included in accrued and other current liabilities in the condensed consolidated balance sheet and the rebates and discounts reflected as reductions to gross accounts receivable for direct sales were immaterial as of June 30, 2024 and December 31, 2023, respectively. Sales to Falikang – China Performance Obligation Substantially all direct roxadustat product sales to distributors in China are made by Falikang. FibroGen Beijing manufactures and supplies commercial product to Falikang. The net transfer price for FibroGen Beijing’s product sales to Falikang is based on a gross transaction price, which is adjusted to account for the 50/50 profit share for the period. The roxadustat sales to Falikang marked the beginning of the Company’s China performance obligation under the Company’s agreements with AstraZeneca . Product revenue is based on the transaction price of the China performance obligation. Revenue is recognized when control of the product is transferred to Falikang, in an amount that reflects the allocation of the transaction price to the performance obligation satisfied during the reporting period, and is expected to continue through 2033, which reflects our best estimates. Any net transaction price in excess of the revenue recognized is added to the deferred balance to date and will be recognized in future periods as the performance obligation is satisfied. Periodically, the Company updates its assumptions such as gross transaction price and profit share, performance period, total sales quantity and other inputs including foreign currency translation impact, among others. Following updates to its estimates, the Company recognized $ 18.1 million and $ 20.6 million from the previously deferred revenue of the China performance obligation during the three and six months ended June 30, 2024, respectively. The product revenue recognized for the three months ended June 30, 2024 included an increase in revenue of $ 12.2 million resulting from changes to estimated variable consideration in the current period relating to performance obligation satisfied in previous periods. Comparatively, following updates to its estimates, the Company deferred $ 3.3 million and $ 1.2 million from the previously deferred revenue of the China performance obligation during three and six months ended June 30, 2023, respectively. The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands): Balance at Additions Recognized as Revenue Currency Balance at Product revenue - AstraZeneca China $ ( 179,851 ) $ ( 53,269 ) $ 73,118 $ 1,409 $ ( 158,593 ) Deferred revenue includes amounts allocated to the China performance obligation under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China and to when the control of the manufactured commercial products is transferred to AstraZeneca. Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the condensed consolidated balance sheets. As of June 30, 2024, deferred revenue included $ 131.3 million related to China performance obligation, which represents the net of $ 158.6 million of deferred revenue presented above and a $ 27.3 million unbilled milestone and co-development revenue under the AstraZeneca China Amendment. As of June 30, 2024 , approximately $ 3.4 million of the above deferred revenue related to the China unit of accounting was included in short-term deferred revenue, which represents the amount of deferred revenue associated with the China unit of accounting that is expected to be recognized within the next 12 months, associated with the commercial sales in China. Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts, mainly related to profit sharing, are presented as reductions to gross accounts receivable from Falikang, which was $ 2.3 million and $ 3.0 million as of June 30, 2024 and December 31, 2023 , respectively. Drug Product Revenue, Net Drug product revenue from commercial-grade active pharmaceutical ingredient (“API”) or bulk drug product sales to Astellas and AstraZeneca was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Astellas Japan Agreement $ ( 366 ) $ 13,809 $ ( 2,571 ) $ 15,541 Astellas Europe Agreement 1,095 463 2,116 840 AstraZeneca U.S./RoW Agreement — — 25,671 — Drug product revenue, net $ 729 $ 14,272 $ 25,216 $ 16,381 Astellas Japan Agreement The Company updates its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment at each balance sheet date. As a result, the Company recorded a reduction to the drug product revenue of $ 0.4 million for the three months ended June 30, 2024. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect foreign exchange impacts and the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, among others. For the three months ended March 31, 2024, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded a reduction to the drug product revenue of $ 2.2 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and foreign exchange impacts, among others. During the three months ended June 30, 2023, the Company fulfilled two shipment obligations under the terms of Astellas Japan Amendment and recognized related drug product revenue of $ 14.4 million in the same period. In addition, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded a reduction to the drug product revenue of $ 0.6 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and foreign exchange impacts, among others. During the three months ended March 31, 2023, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded an adjustment to the drug product revenue of $ 1.7 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and estimated yield from the manufacture of bulk product tablets, among others. As of June 30, 2024, t he balances related to the API price true-up under the Astellas Japan Agreement were $ 2.2 million in accrued liabilities and $ 0.6 million in other long-term liabilities, representing the Company’s best estimate of the timing for these amounts to be paid. As of December 31, 2023, the balances related to the API price true-up under the Astellas Japan Agreement were $ 1.2 million in accrued liabilities and $ 0.7 million in other long-term liabilities. Astellas Europe Agreement The Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement in the prior years. The Company recognized the related fully burdened manufacturing costs as drug product revenue in the respective periods and recorded the constrained transaction price in deferred revenue due to a high degree of uncertainty associated with the variable consideration for revenue recognition purposes. The Company updates its estimate of variable consideration related to the bulk drug product transferred in prior years at each balance sheet date. During the fourth quarter of 2023, the Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and recognized the related fully-burdened manufacturing costs of $ 0.8 million as drug product revenue, and recorded $ 17.7 million as deferred revenue due to a high degree of uncertainty associated with the variable consideration for revenue recognition purposes. In addition, the Company updated its estimate of variable consideration related to the bulk drug product transferred in prior years. Specifically, the change in estimated variable consideration was based on the bulk drug product held by Astellas at the period end, adjusted to reflect the changes in the estimated transfer price, forecast information, shelf-life estimates and other items. As a result, for the year ended December 31, 2023, the Company reclassified $ 38.7 million from the related deferred revenue to accrued liabilities. As of December 31, 2023, the related balance in accrued liabilities was $ 38.6 million. The Company further reclassified $ 5.4 million from the related deferred revenue to accrued liabilities and paid $ 35.3 million to Astellas during the six months ended June 30, 2024. As of June 30, 2024, the balances related to the bulk drug product price true-up under the Astellas Europe Agreement and the Astellas EU Supply Agreement were $ 8.8 million in a ccrued liabilities, representing the Company’s best estimate that these amounts will be paid within the next 12 months. The Company recognized royalty revenue of $ 1.1 million and $ 0.5 million as drug product revenue from the deferred revenue under the Astellas Europe Agreement during the three months ended June 30, 2024 and 2023, and $ 2.1 million and $ 0.8 million for the six months ended June 30, 2024 and 2023, respectively. It is the Company’s best estimate that the remainder of the deferred revenue will be recognized as revenue when uncertainty is resolved, based on the performance of roxadustat product sales in the Astellas territory. The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands): Balance at Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 16,925 ) $ 2,116 $ 5,406 $ ( 9,403 ) AstraZeneca U.S./RoW Agreement As described under AstraZeneca Agreements section above, pursuant to the AstraZeneca Termination and Transition Agreement related to the AstraZeneca U.S./RoW Agreement, the Company and AstraZeneca settled the outstanding balances relating to past transactions under the AstraZeneca Master Supply Agreement. Accordingly, during the three months ended March 31, 2024, the Company accounted for the termination of the AstraZeneca U.S./RoW agreement as a contract modification under the ASC 606 and recorded a cumulative catch-up net adjustment of $ 25.7 million to the drug product revenue. The related accounts receivable of $ 26.0 million and the related accrued liabilities of $ 11.5 million as of March 31, 2024 were settled during the three months ended June 30, 2024. Corresponding to the drug product revenue, during the three months ended March 31, 2024, the Company recorded the related cost of goods sold of $ 21.1 million. Eluminex Agreement In July 2021, FibroGen exclusively licensed to Eluminex Biosciences (Suzhou) Limited (“Eluminex”) global rights to its investigational biosynthetic cornea derived from recombinant human collagen Type III. Under the terms of the agreement with Eluminex, as amended and restated in January 2022, Eluminex made an $ 8.0 million upfront payment to FibroGen during the first quarter of 2022. In addition, FibroGen may receive up to a total of $ 64.0 million in future manufacturing, clinical, regulatory, and commercial milestone payments for the biosynthetic cornea program, as well as $ 36.0 million in commercial milestones for the first recombinant collagen III product that is not the biosynthetic cornea. FibroGen will also be eligible to receive mid-single-digit to low double-digit royalties based upon worldwide net sales of cornea products, and low single-digit to mid-single-digit royalties based upon worldwide net sales of other recombinant human collagen type III products that are not cornea products. In April 2023, FibroGen and Eluminex entered into an Amended and Restated Exclusive License Agreement (“A&R Eluminex Agreement”) in order to add to the license rights to recombinant human collagen Type I (in addition to the rights to collagen Type III that were already licensed). The A&R Eluminex Agreement included additional total upfront payments of $ 1.5 million. During the first quarter of 2023, the Company recognized a $ 3.0 million milestone payment based on Eluminex implanting a biosynthetic cornea in the first patient of its clinical trial in China, and a $ 3.0 million manufacturing related milestone payment. During the second quarter of 2023, the Company recognized a $ 1.0 million upfront payment under the A&R Eluminex Agreement. During the first quarter of 2022, FibroGen and Eluminex entered into a separate contract manufacturing agreement, under which the Company is responsible for supplying the cornea product at cost plus 10 % of its product manufacturing costs until its manufacturing technology is fully transferred to Eluminex, which occurred by the end of 2023 . The related contract manufacturing revenue was recorded as other revenue and included in development and other revenue in the condensed consolidated statement of operations. Such contract manufacturing activity was generally ceased during the first quarter of 2024. Amounts recognized as revenue under the agreements with Eluminex were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 Eluminex License revenue $ — $ 1,000 $ — $ 7,000 Other revenue - contract manufacturing $ — $ 246 $ 116 $ 482

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2024
Business Combinations [Abstract]
Variable Interest Entities	3. Variable Interest Entities Consolidated Variable Interest Entity - Fortis On May 5, 2023 (the “Option Acquisition Date”), the Company entered into an exclusive option agreement to acquire Fortis Therapeutics, Inc. (“Fortis”) with its novel Phase 1 antibody-drug conjugate, FOR46 (now referred to as “FG-3246”), that targets a novel epitope on CD46 preferentially expressed on certain cancer cells. FG-3246 is in development for the treatment of metastatic castration-resistant prostate cancer with potential applicability in other solid tumors and hematologic malignancies. If FibroGen exercises the option to acquire Fortis, it will pay Fortis an option exercise payment of $ 80.0 million, and thereafter, legacy Fortis shareholders would be eligible to receive from FibroGen up to $ 200.0 million in contingent payments associated with the achievement of various regulatory approvals. If FibroGen acquires Fortis, it would also be responsible to pay the University of California, San Francisco, an upstream licensor to Fortis, development milestone fees and a single digit royalty on net sales of therapeutic or diagnostic products arising from the licensing arrangement between Fortis and University of California, San Francisco . If FibroGen chooses not to acquire Fortis, its exclusive license to FG-3246 would expire. Pursuant to an evaluation agreement entered into with Fortis concurrent with the option agreement (together the “Fortis Agreements”), FibroGen has exclusively licensed FG-3246 and will control and fund future research, development, including a Phase 2 clinical study sponsored by FibroGen, and manufacturing of FG-3246 during the up-to four-year option period. As part of the clinical development strategy, FibroGen will continue the work to develop a PET-based biomarker utilizing a radiolabeled version of the targeting antibody for patient selection. Additionally, the Company is obligated to make four quarterly payments totaling $ 5.4 million to Fortis in support of its continued development obligations, of which the last payment was $ 1.7 million and made during the three months ended March 31, 2024. Pursuant to the guidance under ASC 810, Consolidation (“ASC 810”), the Company determined that Fortis is a VIE and that the Company is the primary beneficiary of Fortis, as through the Fortis Agreements the Company has the power to direct activities that most significantly impact the economic performance of Fortis. Therefore, the Company consolidated Fortis starting from the Option Acquisition Date and continues to consolidate as of June 30, 2024. Fortis has authorized and issued common shares and Series A preferred shares. As of the Option Acquisition Date and June 30, 2024 , the Company owned approximately 2 % of Fortis’ Series A preferred shares, which was acquired previously and carried at zero cost. The non-controlling interests (“NCI”) attributable to the common shares is classified as nonredeemable NCI, as it is 100 % owned by third party shareholders. The NCI attributable to the approximately 98 % of Series A preferred shares owned by other investors are classified as redeemable NCI in temporary equity, as the preferred shares are redeemable by the non-controlling shareholders upon occurrence of certain events out of the Company’s control. Subsequent to the Option Acquisition Date, Fortis’ net income is allocated to its common shares and preferred shares based on their respective stated rights. Fortis’ net loss is allocated to its common shares only as the holders of preferred shares do not have a contractual obligation to absorb such losses. As of June 30, 2024, total assets and liabilities of Fortis were immaterial. For the three months ended June 30, 2024, Fortis’ net income (losses) was immaterial. Equity method investment - Unconsolidated VIE - Falikang Falikang is a distribution entity jointly owned by AstraZeneca and FibroGen Beijing. FibroGen Beijing owns 51.1 % of the outstanding shares of Falikang. Pursuant to the guidance under ASC 810, the Company concluded that Falikang qualifies as a VIE. As Falikang is a distribution entity and AstraZeneca is the final decision maker for all the roxadustat commercialization activities, the Company lacks the power criterion, while AstraZeneca meets both the power and economic criteria under the ASC 810 to direct the activities of Falikang that most significantly impact its performance. Therefore, the Company is not the primary beneficiary of this VIE for accounting purposes. As a result, the Company accounts for its investment in Falikang under the equity method, and Falikang is not consolidated into the Company’s condensed consolidated financial statements. The Company records its total investments in Falikang as an equity method investment in an unconsolidated VIE in the condensed consolidated balance sheet. In addition, the Company recognizes its proportionate share of the reported profits or losses of Falikang as investment gain or loss in unconsolidated VIE in the condensed consolidated statement of operations and as an adjustment to its investment in Falikang in the condensed consolidated balance sheet. Falikang has not incurred material profit or loss to date. The Company may provide shareholder loans to Falikang to meet necessary financial obligations as part of its operations. To date, there have been no such loans. The Company’s equity method investment in Falikang was as follows (in thousands): Entity Ownership Percentage Balance at Share of Net Income Currency Balance at Falikang 51.1 % $ 5,290 $ 1,766 $ ( 144 ) $ 6,912 Falikang is considered a related party to the Company. See Note 9, Related Party Transactions , for related disclosures.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands): June 30, 2024 Level 1 Level 2 Level 3 Total Money market funds $ 11,080 $ — $ — $ 11,080 Commercial paper — 52,869 — 52,869 U.S. government bonds 17,908 3,983 — 21,891 Agency bonds — 4,980 — 4,980 Total $ 28,988 $ 61,832 $ — $ 90,820 December 31, 2023 Level 1 Level 2 Level 3 Total Money market funds $ 12,288 $ — $ — $ 12,288 Corporate bonds — 13,992 — 13,992 Commercial paper — 88,289 — 88,289 U.S. government bonds 42,797 4,994 — 47,791 Agency bonds — 9,830 — 9,830 Total $ 55,085 $ 117,105 $ — $ 172,190 The Company’s Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs. There were no transfers of assets between levels during the three months ended June 30, 2024. During the three months ended March 31, 2024, a total of $ 26.3 million of U.S. treasury notes and bills were transferred from Level 1 to Level 2 as such instruments were changed to off-the-run when they were issued before the most recent issue and were still outstanding at measurement day.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components Cash and Cash Equivalents Cash and cash equivalents consisted of the following (in thousands): June 30, 2024 December 31, 2023 Cash $ 49,894 $ 63,396 Commercial paper 52,869 36,016 Money market funds 11,080 12,288 U.S. government bonds 21,891 1,988 Agency bonds 4,980 — Total cash and cash equivalents $ 140,714 $ 113,688 At June 30, 2024 and December 31, 2023, a total of $ 39.3 million and $ 32.2 million of the Company’s cash and cash equivalents were held outside of the U.S. in its foreign subsidiaries to be used primarily for its China operations, respectively. Investments The Company did no t have any short-term or long-term investments as of June 30, 2024. As of December 31, 2023, t he Company’s investments consist primarily of available-for-sale debt investments, and the amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major investments type are summarized in the tables below (in thousands): December 31, 2023 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 13,988 $ 9 $ ( 5 ) $ 13,992 Commercial paper 52,273 — — 52,273 U.S. government bonds 45,783 20 — 45,803 Agency bonds 9,830 1 ( 1 ) 9,830 Total investments $ 121,874 $ 30 $ ( 6 ) $ 121,898 The following table summarizes, for all available for sale securities in an unrealized loss position as of December 31, 2023, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position (in thousands): December 31, 2023 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ — $ — $ 3,495 $ ( 5 ) $ 3,495 $ ( 5 ) U.S. government bonds 4,984 — — — 4,984 — Agency bonds 4,987 ( 1 ) — — 4,987 ( 1 ) Total $ 9,971 $ ( 1 ) $ 3,495 $ ( 5 ) $ 13,466 $ ( 6 ) The Company periodically assesses whether the unrealized losses on its available-for-sale investments were temporary. The Company considers factors such as the severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. Based on the results of its review, the Company did no t recognize any impairment for its available-for-sale investments during the three and six months ended June 30, 2024 and 2023. Inventories Inventories consisted of the following (in thousands): June 30, 2024 December 31, 2023 Raw materials $ 1,018 $ 1,376 Work-in-progress 19,492 34,614 Finished goods 4,887 5,575 Total inventories $ 25,397 $ 41,565 As described under Note 2, Collaboration Agreements, License Agreement and Revenues above, resulting from the AstraZeneca Termination and Transition Agreement related to the AstraZeneca U.S./RoW Agreement, the Company was reimbursed $ 12.6 million for work-in-progress inventory, which was written off and recognized as cost of goods sold during the three months ended March 31, 2024. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): June 30, 2024 December 31, 2023 Contract assets $ 27,258 $ 26,481 Deferred revenues from associated contracts ( 27,258 ) ( 26,481 ) Net contract assets — — Insurance proceeds receivable for litigation settlement 28,500 28,500 Prepaid assets 4,846 6,644 Other current assets 3,590 6,711 Total prepaid expenses and other current assets $ 36,936 $ 41,855 The unbilled contract assets as of June 30, 2024 and December 31, 2023 included $ 23.3 million and $ 22.5 million, respectively, related to unbilled co-development revenue under the AstraZeneca China Amendment. In addition, the unbilled contract assets as of June 30, 2024 and December 31, 2023 each included the $ 4.0 million unbilled regulatory milestone payment under the AstraZeneca China Agreement. See the AstraZeneca China Agreement section in Note 2, Collaboration Agreements, License Agreement and Revenues , for details. As of each of June 30, 2024 and December 31, 2023 , the Company recorded a $ 28.5 million receivable in prepaid expenses and other current assets, corresponding to the accrued litigation settlement of the same amount related to the Company’s agreement in principle with plaintiffs to settle the class action lawsuit. As the Company maintains insurance that covers exposure related to the class action lawsuit, this amount is fully recoverable under the Company’s insurance policies. The determination that the recorded receivables are probable of collection is based on the terms of the applicable insurance policies and communications with the insurers. See the Accrued and Other Current Liabilities section below, and the Legal Proceedings and Other Matters section in Note 10, Commitments and Contingencies , for details. Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): June 30, 2024 December 31, 2023 Preclinical and clinical trial accruals $ 20,091 $ 27,663 API and bulk drug product price true-up 10,991 50,978 Litigation settlement 28,500 28,500 Payroll and related accruals 10,292 20,267 Inventory cost related 8,521 — Accrued co-promotion expenses - current 13,209 10,309 Roxadustat profit share to AstraZeneca 6,909 7,084 Property taxes and other taxes 4,674 6,615 Professional services 5,616 7,103 Current portion of liability related to sale of future revenues 631 5,654 Accrued restructuring charge — 3,697 Other 4,140 5,021 Total accrued and other current liabilities $ 113,574 $ 172,891 The accrued liabilities of $ 11.0 million and $ 51.0 million for API and bulk drug product price true-up as of June 30, 2024 and December 31, 2023, respectively, resulted from changes in estimated variable consideration associated with the API shipments fulfilled under the terms of the Astellas Japan Amendment, the bulk drug product transferred under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and the bulk drug product shipments to AstraZeneca under the terms of the AstraZeneca Master Supply Agreement. During the three months ended June 30, 2024, the Company paid $ 35.3 million to Astellas and $ 11.5 million to AstraZeneca related to accrued amounts. See the Drug Product Revenue, Net section in Note 2, Collaboration Agreements, License Agreement and Revenues, for details. As of June 30, 2024 and December 31, 2023 , the accrued litigation settlement of $ 28.5 million was related to the Company’s agreement in principle with plaintiffs to settle the class action lawsuit, as mentioned above. See the Legal Proceedings and Other Matters section in Note 10, Commitments and Contingencies , for details. The Company recorded an accrued inventory related cost of $ 8.5 million as of June 30, 2024, as part of the cost of goods sold resulting from the AstraZeneca Termination and Transition Agreement, discussed under Note 2, Collaboration Agreements, License Agreement and Revenues .

Senior Secured Term Loan Facili

Senior Secured Term Loan Facilities	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Senior Secured Term Loan Facilities	6. Senior Secured Term Loan Facilities On April 29, 2023, the Company entered into a financing agreement (“Financing Agreement”) with investment funds managed by Morgan Stanley Tactical Value, as lenders (the “Lenders”), and Wilmington Trust, National Association, as the administrative agent, providing for senior secured term loan facilities consisting of (i) a $ 75.0 million initial term loan (the “Initial Term Loan”), (ii) a $ 37.5 million delayed draw term loan that will be funded upon the achievement of certain clinical development milestones (“Delayed Draw Term Loan 1”) and, (iii) an uncommitted delayed draw term loan of up to $ 37.5 million to be funded at the Lenders sole discretion, (“Delayed Draw Term Loan 2” and, together with the Initial Term Loan and Delayed Draw Term Loan 1, the “Term Loans”). Pursuant to the Financing Agreement, the Lenders have funded the Initial Term Loan. The clinical development milestones which could have triggered Delayed Draw Term Loan 1 were not achieved, and the Lenders have not funded Delayed Draw Term Loan 2. As such, these features expired during 2023. The Company has determined that certain other features embedded within the Loan should be bifurcated and accounted for separately as a derivative. At inception and as of June 30, 2024, the fair values of such derivatives were negligible due to the low probability of the underlying events. The Term Loans shall accrue interest at a fixed rate of 14.0 % per annum, payable monthly in arrears. The Term Loans shall mature on May 8, 2026 . The Term Loans will not be subject to amortization payments. The Company is permitted to prepay the Term Loans from time to time, in whole or in part, subject to payment of a make-whole amount equal to the unpaid principal amount of the portion of the Term Loans being repaid or prepaid, plus accrued and unpaid interest of the portion of the Term Loans being repaid or prepaid, plus an amount equal to the remaining scheduled interest payments due on such portion of the Term Loans being repaid or prepaid as if such Term Loans were to remain outstanding until the scheduled maturity date. The initial issuance costs and the related transaction costs, totaling $ 3.7 million is amortized as interest expense using the effective interest method over the term of the Initial Term Loan and are reported on the balance sheet as a direct deduction from the amount of the Initial Term Loan. The effective annual interest rate of the Initial Term Loan was 16.13 % for the three and six months ended June 30, 2024 and 2023 . The Company recorded interest expense of $ 2.9 million and $ 5.8 million, respectively, for the three and six months ended June 30, 2024 . The Company recorded interest expense of $ 1.7 million for the three and six months ended June 30, 2023. As of June 30, 2024 , the related accrued interest was $ 0.4 million. The Company was in compliance with all debt covenants associated with the senior secured term loan facilities as of June 30, 2024 , including maintaining a minimum balance of $ 30 million of unrestricted cash and cash equivalents held in accounts in the U.S. The Company’s senior secured term loan facilities as of June 30, 2024 were as follows (in thousands): June 30, 2024 Principal of senior secured term loan facilities $ 75,000 Less: Unamortized issuance costs and transaction costs ( 2,522 ) Senior secured term loan facilities, ending balance 72,478 Less: Current Portion classified to accrued and other current liabilities — Senior secured term loan facilities, non-current $ 72,478

Liability Related to Sale of Fu

Liability Related to Sale of Future Revenues	6 Months Ended
	Jun. 30, 2024
Liability Related to Sale of Future Royalties [Abstract]
Liability Related to Sale of Future Revenues	7. Liability Related to Sale of Future Revenues On November 4, 2022, the Company entered into a Revenue Interest Financing Agreement (the “RIFA”) with an affiliate of NovaQuest Capital Management (“NovaQuest”), pursuant to which the Company granted NovaQuest 22.5 % of its drug product revenue and 10.0 % ( 20.0 % for fiscal year 2028 and thereafter) of its revenue from milestone payments that it is entitled to under the Astellas Agreements , for a consideration of $ 50.0 million (“Investment Amount”) before advisory fees. In November 2022, the Company received the Investment Amount, net of initial issuance costs, and accounted for it as long-term debt based on the terms of the RIFA because the risks and rewards to NovaQuest are limited by the terms of the transaction. The related debt discount and transaction costs are amortized as interest expense based on the projected balance of the liability as of the beginning of each period. As payments are made to NovaQuest, the balance of the liability related to sale of future revenues is being effectively repaid over the life of the RIFA. The payments to NovaQuest are accounted for as a reduction of debt. The Company may prepay its obligations to NovaQuest in full at any time during the term of RIFA. The prepayment amount varies from $ 80.0 million to $ 125.0 million less any revenue interest payments made up to such prepayment date. Under the RIFA the Company shall pay to NovaQuest up to a specified maximum amount (“Payment Cap”) of (a) $ 100.0 million, if the payment is made on or before December 31, 2028; (b) $ 112.5 million, if the payment is made on or after January 1, 2029, but on or before December 31, 2029; or (c) $ 125.0 million, if the payment is made after January 1, 2030. After January 1, 2028, if the product (as defined) is not commercialized for a consecutive twelve-month period, then, the payments owed under the RIFA by the Company to NovaQuest for each fiscal year shall be the greater of: (i) the amount which would otherwise be due pursuant to revenue interest payments terms; or (ii) $ 10.0 million. Before December 31, 2028, if the sum of all payments under the RIFA paid to NovaQuest, does not equal or exceed $ 62.5 million, then the Company shall pay NovaQuest the difference of these two amounts by no later than March 1, 2029. If, by no later than December 31, 2030, the sum of all payments under the RIFA paid to NovaQuest does not equal or exceed $ 125.0 million, then the Company shall pay NovaQuest the difference of these two amounts by no later than March 1, 2031. NovaQuest will retain this entitlement until it has reached the Payment Cap, at which point 100 % of such revenue interest on future global net sales of Astellas will revert to the Company. Over the course of the RIFA, the effective interest rate is affected by the amount and timing of drug product revenue and revenue from milestone payments recognized, the changes in the timing of forecasted drug product revenue and revenue from milestone payments, and the timing of the Company’s payments to NovaQuest. On a quarterly basis, the Company reassesses the expected total revenue and the timing of such revenue, recalculates the amortization of debt discount and transactions costs and effective interest rate, and adjusts the accounting prospectively as needed. The Company’s estimated effective annual interest rate was 15.63 % as of June 30, 2024. The following table summarizes the activities of the liability related to sale of future revenues for the six months ended June 30, 2024: Six Months Ended Liability related to sale of future revenues - beginning balance $ 57,067 Interest paid ( 5,653 ) Interest expense recognized 3,749 Liability related to sale of future revenues - ending balance 55,163 Less: Current portion classified to accrued and other current liabilities ( 631 ) Liability related to sale of future revenues, non-current $ 54,532 During the three and six months ended June 30, 2024, the Company recognized, under Astellas Agreements, development revenue of $ 0.3 million and $ 0.6 million , respectively, and drug product revenue of $ 0.7 million and $( 0.5 ) million , respectively. See Note 2, Collaboration Agreements, License Agreement and Revenue , for details. During the three and six months ended June 30, 2024 , the Company recognized the related interest expense of $ 1.7 million and $ 3.7 million, respectively. During the three and six months ended June 30, 2023, the Company recognized the related interest expense of $ 1.3 million and $ 3.6 million, respectively. During the first quarter of 2024, the Company paid $ 5.7 million accrued interest. Based on the current estimates of drug product revenue and revenue from milestone payments under the Astellas Agreements, and taking into the consideration of the terms discussed above, the Company anticipates reaching a Payment Cap up to $ 125.0 million by 2031.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes Benefits from income tax for the three and six months ended June 30, 2024 and 2023 were primarily due to foreign taxes. Based upon the weight of available evidence, which includes its historical operating performance, reported cumulative net losses since inception, the Company has established and continues to maintain a full valuation allowance against its net deferred tax assets as it does not currently believe that realization of those assets is more likely than not.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	9. Related Party Transactions Astellas is an equity investor in the Company and is considered a related party. The Company recorded license and development revenue related to collaboration agreements with Astellas of $ 0.3 million and $ 1.8 million for the three months ended June 30, 2024 and 2023, and $ 0.6 million and $ 3.5 million for the six months ended June 30, 2024 and 2023, respectively. In addition, the Company recorded drug product revenue from Astellas of $ 0.7 million and $ 14.3 million for the three months ended June 30, 2024 and 2023, and $( 0.5 ) million and $ 16.4 million for the six months ended June 30, 2024 and 2023, respectively. See Note 2, Collaboration Agreements, License Agreement and Revenues , for details. The Company’s expense related to collaboration agreements with Astellas was immaterial for each of the three and six months ended June 30, 2024 and 2023. As of June 30, 2024 and December 31, 2023 , accounts receivable from Astellas were $ 0.3 million and $ 0.8 million, respectively. As of June 30, 2024 and December 31, 2023 , total deferred revenue from Astellas was $ 9.4 million and $ 16.9 million, respectively. As of June 30, 2024, the amounts due to Astellas, included in accrued and other current liabilities, and other long-term liabilities, totaled $ 11.6 million. As of December 31, 2023 , the amount due to Astellas, included in accrued and other current liabilities, and other long-term liabilities, totaled $ 40.5 million. Falikang, an entity jointly owned by FibroGen Beijing and AstraZeneca, is an unconsolidated VIE accounted for as an equity method investment, and considered as a related party to the Company. FibroGen Beijing owns 51.1 % of Falikang’s equity. See the Equity method investment - Unconsolidated VIE - Falikang section of Note 3, Variable Interest Entities , for details. The net product revenue from Falikang was $ 46.0 million and $ 20.5 million for the three months ended June 30, 2024 and 2023, and $ 73.1 million and $ 41.9 million for the six months ended June 30, 2024 and 2023, respectively. See the Product Revenue, Net section in Note 2, Collaboration Agreements, License Agreement and Revenues , for details. The investment income in Falikang was $ 1.2 million and $ 0.6 million for the three months ended June 30, 2024 and 2023 and $ 1.8 million and $ 1.3 million for the six months ended June 30, 2024 and 2023, respectively. As of June 30, 2024 and December 31, 2023, the Company’s equity method investment in Falikang was $ 6.9 million and $ 5.3 million , respectively. See the Equity method investment - Unconsolidated VIE - Falikang section of Note 3, Variable Interest Entities , for details. The other income from Falikang was immaterial for each of the three and six months ended June 30, 2024 and 2023. As of June 30, 2024 and December 31, 2023 , accounts receivable, net, from Falikang, were $ 3.8 million and $ 5.2 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Contract Obligations As of June 30, 2024 , the Company had outstanding total non-cancelable purchase obligations of $ 19.7 million, including $ 11.2 million for manufacture and supply of pamrevlumab, $ 0.8 million for manufacture and supply of roxadustat, and $ 7.6 million for other purchases and programs. The Company expects to fulfill its commitments under these agreements in the normal course of business, and as such, no liability has been recorded. Some of the Company’s license agreements provide for periodic maintenance fees over specified time periods, as well as payments by the Company upon the achievement of development, regulatory and commercial milestones. As of June 30, 2024 , future milestone payments for research and preclinical stage development programs consisted of up to approximately $ 697.9 million in total potential future milestone payments under the Company’s license agreements with HiFiBiO (HK) Ltd. (d.b.a. HiFiBiO Therapeutics) (for Gal-9 and CCR8), Medarex, Inc. and others. These milestone payments generally become due and payable only upon the achievement of certain developmental, clinical, regulatory and/or commercial milestones. The event triggering such payment or obligation has not yet occurred. As of June 30, 2024, the Company had $ 73.9 million of operating lease liabilities. In addition, see Note 6, Senior Secured Term Loan Facilities and Note 7, Liability Related to Sale of Future Revenues for details of the related obligations. Legal Proceedings and Other Matters From time to time, the Company is a party to various legal actions, both inside and outside the U.S., arising in the ordinary course of its business or otherwise. The Company accrues amounts, to the extent they can be reasonably estimated, that the Company believes will result in a probable loss (including, among other things, probable settlement value) to adequately address any liabilities related to legal proceedings and other loss contingencies. A loss or a range of loss is disclosed when it is reasonably possible that a material loss will incur and can be estimated, or when it is reasonably possible that the amount of a loss, when material, will exceed the recorded provision. The Company did not have any material accruals for any active legal action, except for the class action settlement mentioned below, in its condensed consolidated balance sheet as of June 30, 2024, as the Company could not predict the ultimate outcome of these matters, or reasonably estimate the potential exposure. Between April 2021 and May 2021, five putative securities class action complaints were filed against FibroGen and certain of its current and former executive officers (collectively, the “Defendants”) in the U.S. District Court for the Northern District of California. The lawsuits allege that Defendants violated the Securities Exchange Act of 1934 by making materially false and misleading statements regarding FibroGen’s Phase 3 clinical studies data and prospects for U.S. Food and Drug Administration approval. On August 30, 2021, the Court consolidated the actions and appointed a group of lead plaintiffs. On October 17, 2023, the parties reached an agreement in principle to settle the class action at $ 28.5 million. Accordingly, as of December 31, 2023, the Company recorded the $ 28.5 million in accrued and other current liabilities in the consolidated balance sheet. The Company maintains insurance that covers exposure related to the class action lawsuit. As the amount is fully recoverable under the Company’s insurance policies, the Company recorded a corresponding receivable in prepaid expenses and other current assets in the condensed consolidated balance sheet. The determination that the recorded receivables are probable of collection is based on the terms of the applicable insurance policies and communications with the insurers. The Court preliminarily approved the settlement on February 13, 2024 and approved the settlement Plan of Allocations on May 28, 2024 and Plaintiffs’ motion for attorney’s fees on August 1, 2024, reserving further orders on the final judgment until after the claims and distribution process was completed. Another case, filed on May 25, 2023, against the same defendants, asserting similar claims as the class action and additional common-law and California state fraud claims was voluntarily dismissed on December 20, 2023. Between July 30, 2021 and April 3, 2024, seven shareholder derivative complaints were filed, naming as defendants certain of our current and former officers and certain current and former members of our board, as well as FibroGen as nominal defendants (the “Derivative Lawsuits”). Of these Derivative Lawsuits, four were filed in the Delaware Court of Chancery (the “Delaware Chancery Derivative Actions”), two were filed in the U.S. District Court for the District of Delaware (the “Delaware Federal Derivative Actions”), and one was filed in the U.S. District Court for the Northern District of California (the “California Federal Derivative Action”). The plaintiffs assert state and federal claims based on some of the same alleged misstatements as the securities class action complaint. The complaints seek unspecified damages, attorneys’ fees, and other costs. The status of the seven Derivative Lawsuits is currently as follows: • Two of the Delaware Chancery Derivative Actions, filed on April 14, 2022, and June 1, 2023, have been consolidated (the “Delaware Chancery Consolidated Derivative”). On February 1, 2024, Defendants moved to dismiss the Delaware Chancery Consolidated Derivative action and a hearing on the motion was held on May 9, 2024. In the other two Delaware Chancery Derivative Actions, filed in the Delaware Court of Chancery on December 3, 2023 and April 3, 2024, Defendants have not been formally served, though the parties are in the process of negotiating a stay of the actions pending resolution of the motion to dismiss the Delaware Chancery Consolidated Derivative action; • Two of the Delaware Federal Derivative Actions remain stayed pending resolution of the motion to dismiss the Delaware Chancery Consolidated Derivative action; and • The California Federal Derivative Action was voluntarily dismissed on January 22, 2024. The Company believes that the claims asserted in the Derivative Lawsuits are without merit and it intends to vigorously defend against them. However, any litigation is inherently uncertain, and any judgment or injunctive relief entered against FibroGen, or any adverse settlement could materially and adversely impact its business, results of operations, financial condition, and prospects. In the fourth quarter of 2021, the Company received a subpoena from the SEC requesting documents related to roxadustat’s pooled cardiovascular safety data. The SEC followed up with a subpoena for additional documents in the second quarter of 2024. The Company is fully cooperating with the SEC. The Company cannot predict with any degree of certainty the outcome of the SEC’s investigation or determine the extent of any potential liabilities. The Company also cannot predict whether there will be any loss as a result of the investigation nor can it provide an estimate of the possible loss or range of loss. Any adverse outcome in this matter or any related proceeding could expose the Company to substantial damages, penalties, or reputational harm that may have a material adverse impact on the Company’s business, results of operations, financial condition, growth prospects, and price of its common stock. Between 2022 and 2024, the Company’s Board of Directors received six litigation demands from purported shareholders of the Company, asking the Board of Directors to investigate and take action against certain current and former officers and directors of the Company for alleged wrongdoing based on the same allegations in the pending derivative and securities class action lawsuits. The Company may in the future receive such additional demands. Starting in October 2021, certain challenges have been filed with the China National Intellectual Property Administration against patents which claim a crystalline form of roxadustat. Final resolution of such proceedings will take time and the Company could not predict the ultimate outcome, or reasonably estimate the potential exposure. Indemnification Agreements The Company enters into standard indemnification arrangements in the ordinary course of business, including for example, service, manufacturing and collaboration agreements. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, including in connection with intellectual property infringement claims by any third party with respect to its technology. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the extent permissible under applicable law. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company believes the estimated fair value of these arrangements is minimal.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2024
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event On July 30, 2024, the Company reported results from Pancreatic Cancer Action Network’s (“PanCAN’s”) Precision Promise SM adaptive trial platform that included pamrevlumab, its antibody developed to inhibit the activity of CTGF, in combination with standard-of-care chemotherapy treatments for pancreatic cancer, for patients with metastatic pancreatic cancer. The pamrevlumab experimental arm in PanCAN’s Precision Promise Phase 2/3 adaptive platform trial did not meet the primary endpoint of overall survival as determined by the protocol pre-specified Bayesian statistical analysis. On July 30, 2024, the Company also reported results from LAPIS, its double-blind placebo-controlled Phase 3 clinical program for pamrevlumab in 284 LAPC patients randomized at a 1:1 ratio to receive either pamrevlumab or placebo, in each case in combination with chemotherapy (either FOLFIRINOX or gemcitabine plus nab-paclitaxel). The study did not meet the primary endpoint of overall survival. Responding to the above results, the Company is implementing an immediate and significant cost reduction plan in the U.S., including terminating pamrevlumab research and development investment and expeditiously wind down remaining obligations, and reducing U.S. workforce by approximately 75 % (the Company notified employees on August 2, 2024). The Company expects that the majority of the restructuring charges related to the headcount reductions, primarily consisting of notice period and severance payments, accrued vacation and employee benefits contributions, will be recognized in the second half of 2024, and that the implementation of the headcount reductions, including cash payments, will be substantially complete by the end of the first quarter of 2025. The Company may incur additional expenses not currently contemplated due to events associated with these cost reduction measures.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Description of Operations	Description of Operations FibroGen, Inc. (“FibroGen” or the “Company”) is headquartered in San Francisco, California, with subsidiary offices in Beijing and Shanghai, People’s Republic of China (“China”). FibroGen is developing and commercializing a diversified pipeline of novel therapeutics that work at the frontier of cancer biology and anemia. Roxadustat is an oral small molecule inhibitor of hypoxia-inducible factor prolyl hydroxylase activity. Roxadustat (爱瑞卓 ® , EVRENZO TM ) is approved in China, Europe, Japan, and numerous other countries for the treatment of anemia in chronic kidney disease for patients who are on dialysis and not on dialysis. Roxadustat is in clinical development for chemotherapy-induced anemia in China. FG-3246 is a first-in-class antibody-drug conjugate targeting a novel epitope on CD46 that is in development for metastatic castration-resistant prostate cancer and other cancer indications. FibroGen also has a pipeline of preclinical product candidates, FG-3165 and FG-3175, to address unmet patient needs in oncology.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements include the accounts of FibroGen, its wholly-owned subsidiaries and its majority-owned subsidiaries, as well as any variable interest entity (“VIE”) for which FibroGen is the primary beneficiary. All inter-company transactions and balances have been eliminated in consolidation. For any VIE for which FibroGen is not the primary beneficiary, the Company uses the equity method of accounting. The Company operates as one reportable segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs. The unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) applicable to interim financial reporting and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the United States (“U.S.”) Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and footnote disclosures normally included in the annual consolidated financial statements. The financial information included herein should be read in conjunction with the consolidated financial statements and related notes in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed on February 26, 2024. Based on its current operating plan, which contemplates the maintenance of a minimum balance of $ 30 million of unrestricted cash and cash equivalents held in accounts in the U.S., as required under the debt covenants associated with the senior secured term loan facilities, the Company believes that its existing cash and cash equivalents and accounts receivable will be sufficient to meet its anticipated cash requirements for at least the next 12 months from the date of issuance of the financial statements. However, the Company may need additional capital to fund its operations and its liquidity assumptions may materially differ (including assumptions with respect to our research and development expenses, revenue expectations, contractual obligations, ability to repatriate cash from China, partnering or monetization of assets, and others). In addition, the Company may elect to raise additional funds at any time through equity, equity-linked, debt financing arrangements or from other sources.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated 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 at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include valuation and recognition of revenue and deferred revenue, specifically, estimates in variable consideration for drug product sales, and estimates in transaction price per unit for the China performance obligation. On an ongoing basis, management reviews these estimates and assumptions. Changes in facts and circumstances may alter such estimates and actual results could differ from those estimates. In the Company’s opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of its financial position, results of operations and cash flows for the interim periods presented.
Net Loss per Share	Net Loss per Share Potential common shares that would have the effect of increasing diluted earnings per share are considered to be anti-dilutive and as such, these shares are not included in the calculation of diluted earnings per share. The Company reported a net loss for each of the three and six months ended June 30, 2024 and 2023. Therefore, dilutive common shares are not assumed to have been issued since their effect is anti-dilutive for these periods. Diluted weighted average shares excluded the following potential common shares related to s tock options, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), total shareholder return (“TSR”) awards and shares to be purchased under the 2014 Employee Stock Purchase Plan (“ESPP”) for the periods presented as they were anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Employee stock options 15,072 9,701 13,792 8,857 RSUs, PRSUs and TSR awards 3,899 3,084 3,922 3,078 ESPP 460 747 496 554 19,431 13,532 18,210 12,489
Risks and Uncertainties	Risks and Uncertainties The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, the results of clinical trials and the achievement of milestones, research developments, actions by regulatory authorities, market acceptance of the Company’s product candidates, competition from other products and larger companies, the liquidity and capital resources of the Company, intellectual property protection for the Company’s proprietary technology, strategic relationships, and dependence on key individuals, suppliers, clinical organization, and other third parties.
Recently Issued Accounting Guidance Not Yet Adopted	Recently Issued Accounting Guidance Not Yet Adopted In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires all public entities, including public entities with a single reportable segment, to provide in interim and annual periods one or more measures of segment profit or loss used by the chief operating decision maker to allocate resources and assess performance. In addition, this guidance requires disclosures of significant segment expenses and other segment items as well as incremental qualitative disclosures. This guidance is effective for fiscal years beginning after December 15, 2023, and interim periods after December 15, 2024, with retrospective application required, and early adoption permitted. The Company is currently in the process of evaluating the effects of this guidance on its related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which requires enhanced income tax disclosures, including specific categories and disaggregation of information in the effective tax rate reconciliation, disaggregated information related to income taxes paid, income or loss from continuing operations before income tax expense or benefit, and income tax expense or benefit from continuing operations. This guidance is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company is currently in the process of evaluating the impact of this pronouncement on its related disclosures.
Collaboration Agreements, License Agreement and Revenues	Astellas Agreements Astellas Japan Agreement In June 2005, the Company entered into a collaboration agreement with Astellas Pharma Inc. (“Astellas”) for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in Japan (“Astellas Japan Agreement”). Under this agreement, Astellas agreed to pay license fees, other upfront consideration and various milestone payments, totaling $ 172.6 million . The Astellas Japan Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range of the list price published by Japan’s Ministry of Health, Labour and Welfare, adjusted for certain elements, after commercial launch. The aggregate amount of consideration received through June 30, 2024 totaled $ 105.1 million , excluding drug product revenue that is discussed under the Drug Product Revenue, Net section below. Based on its current development plans for roxadustat in Japan, the Company does not expect to receive most or all of the additional potential milestones under the Astellas Japan Agreement.
Product Revenue, Net	Product Revenue, Net Product revenue, net from the sales of roxadustat commercial product in China was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Direct Sales: Gross revenue $ 4,046 $ 3,607 $ 7,831 $ 6,667 Discounts and rebates ( 408 ) ( 229 ) ( 767 ) ( 503 ) Sales returns — ( 1 ) ( 1 ) 1 Direct sales revenue, net 3,638 3,377 7,063 6,165 Sales to Falikang: Gross transaction price 49,352 42,153 92,912 76,402 Profit share ( 21,397 ) ( 18,312 ) ( 40,420 ) ( 33,300 ) Net transaction price 27,955 23,841 52,492 43,102 Decrease (increase) in deferred revenue 18,050 ( 3,329 ) 20,626 ( 1,218 ) Sales to Falikang revenue, net 46,005 20,512 73,118 41,884 Total product revenue, net $ 49,643 $ 23,889 $ 80,181 $ 48,049 Direct Sales Product revenue from direct roxadustat product sales to distributors in China is recognized in an amount that reflects the consideration that the Company expects to be entitled to in exchange for those products, net of various sales rebates and discounts. The total discounts and rebates were immaterial for the periods presented. Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts are presented as reductions to gross accounts receivable from the distributor, or as a current liability to the distributor to the extent that the total amount exceeds the gross accounts receivable or when the Company expects to settle the discount in cash. The Company’s legal right to offset is determined at the individual distributor level. The contract liabilities were included in accrued and other current liabilities in the condensed consolidated balance sheet and the rebates and discounts reflected as reductions to gross accounts receivable for direct sales were immaterial as of June 30, 2024 and December 31, 2023, respectively. Sales to Falikang – China Performance Obligation Substantially all direct roxadustat product sales to distributors in China are made by Falikang. FibroGen Beijing manufactures and supplies commercial product to Falikang. The net transfer price for FibroGen Beijing’s product sales to Falikang is based on a gross transaction price, which is adjusted to account for the 50/50 profit share for the period. The roxadustat sales to Falikang marked the beginning of the Company’s China performance obligation under the Company’s agreements with AstraZeneca . Product revenue is based on the transaction price of the China performance obligation. Revenue is recognized when control of the product is transferred to Falikang, in an amount that reflects the allocation of the transaction price to the performance obligation satisfied during the reporting period, and is expected to continue through 2033, which reflects our best estimates. Any net transaction price in excess of the revenue recognized is added to the deferred balance to date and will be recognized in future periods as the performance obligation is satisfied. Periodically, the Company updates its assumptions such as gross transaction price and profit share, performance period, total sales quantity and other inputs including foreign currency translation impact, among others. Following updates to its estimates, the Company recognized $ 18.1 million and $ 20.6 million from the previously deferred revenue of the China performance obligation during the three and six months ended June 30, 2024, respectively. The product revenue recognized for the three months ended June 30, 2024 included an increase in revenue of $ 12.2 million resulting from changes to estimated variable consideration in the current period relating to performance obligation satisfied in previous periods. Comparatively, following updates to its estimates, the Company deferred $ 3.3 million and $ 1.2 million from the previously deferred revenue of the China performance obligation during three and six months ended June 30, 2023, respectively. The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands): Balance at Additions Recognized as Revenue Currency Balance at Product revenue - AstraZeneca China $ ( 179,851 ) $ ( 53,269 ) $ 73,118 $ 1,409 $ ( 158,593 ) Deferred revenue includes amounts allocated to the China performance obligation under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China and to when the control of the manufactured commercial products is transferred to AstraZeneca. Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the condensed consolidated balance sheets. As of June 30, 2024, deferred revenue included $ 131.3 million related to China performance obligation, which represents the net of $ 158.6 million of deferred revenue presented above and a $ 27.3 million unbilled milestone and co-development revenue under the AstraZeneca China Amendment. As of June 30, 2024 , approximately $ 3.4 million of the above deferred revenue related to the China unit of accounting was included in short-term deferred revenue, which represents the amount of deferred revenue associated with the China unit of accounting that is expected to be recognized within the next 12 months, associated with the commercial sales in China. Due to the Company’s legal right to offset, at each balance sheet date, the rebates and discounts, mainly related to profit sharing, are presented as reductions to gross accounts receivable from Falikang, which was $ 2.3 million and $ 3.0 million as of June 30, 2024 and December 31, 2023 , respectively.
Drug Product Revenue	Drug Product Revenue, Net Drug product revenue from commercial-grade active pharmaceutical ingredient (“API”) or bulk drug product sales to Astellas and AstraZeneca was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Astellas Japan Agreement $ ( 366 ) $ 13,809 $ ( 2,571 ) $ 15,541 Astellas Europe Agreement 1,095 463 2,116 840 AstraZeneca U.S./RoW Agreement — — 25,671 — Drug product revenue, net $ 729 $ 14,272 $ 25,216 $ 16,381 Astellas Japan Agreement The Company updates its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment at each balance sheet date. As a result, the Company recorded a reduction to the drug product revenue of $ 0.4 million for the three months ended June 30, 2024. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect foreign exchange impacts and the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, among others. For the three months ended March 31, 2024, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded a reduction to the drug product revenue of $ 2.2 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and foreign exchange impacts, among others. During the three months ended June 30, 2023, the Company fulfilled two shipment obligations under the terms of Astellas Japan Amendment and recognized related drug product revenue of $ 14.4 million in the same period. In addition, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded a reduction to the drug product revenue of $ 0.6 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and foreign exchange impacts, among others. During the three months ended March 31, 2023, the Company updated its estimate of variable consideration related to the API shipments fulfilled under the terms of Astellas Japan Amendment, and accordingly recorded an adjustment to the drug product revenue of $ 1.7 million. Specifically, the change in estimated variable consideration was based on the API held by Astellas at period end, adjusted to reflect the changes in the estimated bulk product strength mix intended to be manufactured by Astellas, and estimated yield from the manufacture of bulk product tablets, among others. As of June 30, 2024, t he balances related to the API price true-up under the Astellas Japan Agreement were $ 2.2 million in accrued liabilities and $ 0.6 million in other long-term liabilities, representing the Company’s best estimate of the timing for these amounts to be paid. As of December 31, 2023, the balances related to the API price true-up under the Astellas Japan Agreement were $ 1.2 million in accrued liabilities and $ 0.7 million in other long-term liabilities. Astellas Europe Agreement The Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement in the prior years. The Company recognized the related fully burdened manufacturing costs as drug product revenue in the respective periods and recorded the constrained transaction price in deferred revenue due to a high degree of uncertainty associated with the variable consideration for revenue recognition purposes. The Company updates its estimate of variable consideration related to the bulk drug product transferred in prior years at each balance sheet date. During the fourth quarter of 2023, the Company transferred bulk drug product for commercial purposes under the terms of the Astellas Europe Agreement and the Astellas EU Supply Agreement, and recognized the related fully-burdened manufacturing costs of $ 0.8 million as drug product revenue, and recorded $ 17.7 million as deferred revenue due to a high degree of uncertainty associated with the variable consideration for revenue recognition purposes. In addition, the Company updated its estimate of variable consideration related to the bulk drug product transferred in prior years. Specifically, the change in estimated variable consideration was based on the bulk drug product held by Astellas at the period end, adjusted to reflect the changes in the estimated transfer price, forecast information, shelf-life estimates and other items. As a result, for the year ended December 31, 2023, the Company reclassified $ 38.7 million from the related deferred revenue to accrued liabilities. As of December 31, 2023, the related balance in accrued liabilities was $ 38.6 million. The Company further reclassified $ 5.4 million from the related deferred revenue to accrued liabilities and paid $ 35.3 million to Astellas during the six months ended June 30, 2024. As of June 30, 2024, the balances related to the bulk drug product price true-up under the Astellas Europe Agreement and the Astellas EU Supply Agreement were $ 8.8 million in a ccrued liabilities, representing the Company’s best estimate that these amounts will be paid within the next 12 months. The Company recognized royalty revenue of $ 1.1 million and $ 0.5 million as drug product revenue from the deferred revenue under the Astellas Europe Agreement during the three months ended June 30, 2024 and 2023, and $ 2.1 million and $ 0.8 million for the six months ended June 30, 2024 and 2023, respectively. It is the Company’s best estimate that the remainder of the deferred revenue will be recognized as revenue when uncertainty is resolved, based on the performance of roxadustat product sales in the Astellas territory. The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands): Balance at Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 16,925 ) $ 2,116 $ 5,406 $ ( 9,403 ) AstraZeneca U.S./RoW Agreement As described under AstraZeneca Agreements section above, pursuant to the AstraZeneca Termination and Transition Agreement related to the AstraZeneca U.S./RoW Agreement, the Company and AstraZeneca settled the outstanding balances relating to past transactions under the AstraZeneca Master Supply Agreement. Accordingly, during the three months ended March 31, 2024, the Company accounted for the termination of the AstraZeneca U.S./RoW agreement as a contract modification under the ASC 606 and recorded a cumulative catch-up net adjustment of $ 25.7 million to the drug product revenue. The related accounts receivable of $ 26.0 million and the related accrued liabilities of $ 11.5 million as of March 31, 2024 were settled during the three months ended June 30, 2024. Corresponding to the drug product revenue, during the three months ended March 31, 2024, the Company recorded the related cost of goods sold of $ 21.1 million.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	Diluted weighted average shares excluded the following potential common shares related to s tock options, service-based restricted stock units (“RSUs”), performance-based RSUs (“PRSUs”), total shareholder return (“TSR”) awards and shares to be purchased under the 2014 Employee Stock Purchase Plan (“ESPP”) for the periods presented as they were anti-dilutive (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Employee stock options 15,072 9,701 13,792 8,857 RSUs, PRSUs and TSR awards 3,899 3,084 3,922 3,078 ESPP 460 747 496 554 19,431 13,532 18,210 12,489

Collaboration Agreements, Lic_2

Collaboration Agreements, License Agreement and Revenues (Tables)	6 Months Ended
	Jun. 30, 2024
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations and Product Revenue Net	Product revenue, net from the sales of roxadustat commercial product in China was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Direct Sales: Gross revenue $ 4,046 $ 3,607 $ 7,831 $ 6,667 Discounts and rebates ( 408 ) ( 229 ) ( 767 ) ( 503 ) Sales returns — ( 1 ) ( 1 ) 1 Direct sales revenue, net 3,638 3,377 7,063 6,165 Sales to Falikang: Gross transaction price 49,352 42,153 92,912 76,402 Profit share ( 21,397 ) ( 18,312 ) ( 40,420 ) ( 33,300 ) Net transaction price 27,955 23,841 52,492 43,102 Decrease (increase) in deferred revenue 18,050 ( 3,329 ) 20,626 ( 1,218 ) Sales to Falikang revenue, net 46,005 20,512 73,118 41,884 Total product revenue, net $ 49,643 $ 23,889 $ 80,181 $ 48,049
Schedule of Drug Product Revenue	Drug product revenue from commercial-grade active pharmaceutical ingredient (“API”) or bulk drug product sales to Astellas and AstraZeneca was as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Astellas Japan Agreement $ ( 366 ) $ 13,809 $ ( 2,571 ) $ 15,541 Astellas Europe Agreement 1,095 463 2,116 840 AstraZeneca U.S./RoW Agreement — — 25,671 — Drug product revenue, net $ 729 $ 14,272 $ 25,216 $ 16,381
Summary of Amounts Recognized as Revenue	Amounts recognized as revenue under the agreements with Eluminex were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 Eluminex License revenue $ — $ 1,000 $ — $ 7,000 Other revenue - contract manufacturing $ — $ 246 $ 116 $ 482
Drug Product Revenue, Net [Member]
Roll-forward of Related Contract Liabilities	The following table includes a roll-forward of the above-mentioned deferred revenues that are considered as contract liabilities related to drug product (in thousands): Balance at Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 16,925 ) $ 2,116 $ 5,406 $ ( 9,403 )
AstraZeneca Agreements [Member]
Roll-forward of Related Contract Liabilities	The following table includes a roll-forward of the related deferred revenue that is considered as a contract liability (in thousands): Balance at Additions Recognized as Revenue Currency Balance at Product revenue - AstraZeneca China $ ( 179,851 ) $ ( 53,269 ) $ 73,118 $ 1,409 $ ( 158,593 )
Japan [Member]
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations and Product Revenue Net	The transaction price related to consideration received through June 30, 2024 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Japan Agreement (in thousands): Astellas Japan Agreement Total Consideration License $ 100,347 Development revenue 17,100 Total license and development revenue $ 117,447
Europe [Member]
Summary of License Revenue and Development Revenue Recognized under Agreement	Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 Astellas Europe Agreement Development revenue $ 318 $ 1,806 $ 606 $ 3,335
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations and Product Revenue Net	The transaction price related to consideration received through June 30, 2024 and accounts receivable has been allocated to each of the following performance obligations under the Astellas Europe Agreement as follows (in thousands): Astellas Europe Agreement Total Consideration License $ 618,975 Development revenue 287,322 Total license and development revenue $ 906,297
U.S./RoW and China [Member]
Summary of License Revenue and Development Revenue Recognized under Agreement	Amounts recognized as license revenue and development revenue under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement were as follows for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, Agreement Performance Obligation 2024 2023 2024 2023 AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement Development revenue $ ( 50 ) $ 2,273 $ 418 $ 4,305
Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations and Product Revenue Net	The transaction price relat ed to consideration received and accounts receivable through the termination of the AstraZeneca U.S./RoW Agreement has been allocated to each of the performance obligations under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, including $ 344.5 million for license, $ 625.5 million for co-development, information sharing and committee services, and $ 427.5 million for China performance obligation (with cumulative revenue of $ 268.9 million through June 30, 2024) that is recognized as product revenue, as described under Product Revenue, Net section below.

Variable Interest Entity (Table

Variable Interest Entity (Tables)	6 Months Ended
	Jun. 30, 2024
Business Combinations [Abstract]
Summary of Equity Method Investment	The Company’s equity method investment in Falikang was as follows (in thousands): Entity Ownership Percentage Balance at Share of Net Income Currency Balance at Falikang 51.1 % $ 5,290 $ 1,766 $ ( 144 ) $ 6,912

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Values of Financial Assets Measured on Recurring Basis	The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands): June 30, 2024 Level 1 Level 2 Level 3 Total Money market funds $ 11,080 $ — $ — $ 11,080 Commercial paper — 52,869 — 52,869 U.S. government bonds 17,908 3,983 — 21,891 Agency bonds — 4,980 — 4,980 Total $ 28,988 $ 61,832 $ — $ 90,820 December 31, 2023 Level 1 Level 2 Level 3 Total Money market funds $ 12,288 $ — $ — $ 12,288 Corporate bonds — 13,992 — 13,992 Commercial paper — 88,289 — 88,289 U.S. government bonds 42,797 4,994 — 47,791 Agency bonds — 9,830 — 9,830 Total $ 55,085 $ 117,105 $ — $ 172,190

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents	Cash and cash equivalents consisted of the following (in thousands): June 30, 2024 December 31, 2023 Cash $ 49,894 $ 63,396 Commercial paper 52,869 36,016 Money market funds 11,080 12,288 U.S. government bonds 21,891 1,988 Agency bonds 4,980 — Total cash and cash equivalents $ 140,714 $ 113,688
Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments	he Company’s investments consist primarily of available-for-sale debt investments, and the amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major investments type are summarized in the tables below (in thousands): December 31, 2023 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 13,988 $ 9 $ ( 5 ) $ 13,992 Commercial paper 52,273 — — 52,273 U.S. government bonds 45,783 20 — 45,803 Agency bonds 9,830 1 ( 1 ) 9,830 Total investments $ 121,874 $ 30 $ ( 6 ) $ 121,898
Summary of Available for Sale Securities in Unrealized Loss Position, Fair Value and Gross Unrealized Loss By Length of Time Security in Continual Unrealized Loss Position	The following table summarizes, for all available for sale securities in an unrealized loss position as of December 31, 2023, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position (in thousands): December 31, 2023 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ — $ — $ 3,495 $ ( 5 ) $ 3,495 $ ( 5 ) U.S. government bonds 4,984 — — — 4,984 — Agency bonds 4,987 ( 1 ) — — 4,987 ( 1 ) Total $ 9,971 $ ( 1 ) $ 3,495 $ ( 5 ) $ 13,466 $ ( 6 )
Schedule of Inventory	Inventories consisted of the following (in thousands): June 30, 2024 December 31, 2023 Raw materials $ 1,018 $ 1,376 Work-in-progress 19,492 34,614 Finished goods 4,887 5,575 Total inventories $ 25,397 $ 41,565
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): June 30, 2024 December 31, 2023 Contract assets $ 27,258 $ 26,481 Deferred revenues from associated contracts ( 27,258 ) ( 26,481 ) Net contract assets — — Insurance proceeds receivable for litigation settlement 28,500 28,500 Prepaid assets 4,846 6,644 Other current assets 3,590 6,711 Total prepaid expenses and other current assets $ 36,936 $ 41,855
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): June 30, 2024 December 31, 2023 Preclinical and clinical trial accruals $ 20,091 $ 27,663 API and bulk drug product price true-up 10,991 50,978 Litigation settlement 28,500 28,500 Payroll and related accruals 10,292 20,267 Inventory cost related 8,521 — Accrued co-promotion expenses - current 13,209 10,309 Roxadustat profit share to AstraZeneca 6,909 7,084 Property taxes and other taxes 4,674 6,615 Professional services 5,616 7,103 Current portion of liability related to sale of future revenues 631 5,654 Accrued restructuring charge — 3,697 Other 4,140 5,021 Total accrued and other current liabilities $ 113,574 $ 172,891

Senior Secured Term Loan Faci_2

Senior Secured Term Loan Facilities (Table)	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Summary of Senior Secured Term Loan Facilities	The Company’s senior secured term loan facilities as of June 30, 2024 were as follows (in thousands): June 30, 2024 Principal of senior secured term loan facilities $ 75,000 Less: Unamortized issuance costs and transaction costs ( 2,522 ) Senior secured term loan facilities, ending balance 72,478 Less: Current Portion classified to accrued and other current liabilities — Senior secured term loan facilities, non-current $ 72,478

Liability Related to Sale of _2

Liability Related to Sale of Future Revenues (Tables)	6 Months Ended
	Jun. 30, 2024
Liability Related to Sale of Future Royalties [Abstract]
Schedule of Activities of Liability Related to Sale of Future Revenues	The following table summarizes the activities of the liability related to sale of future revenues for the six months ended June 30, 2024: Six Months Ended Liability related to sale of future revenues - beginning balance $ 57,067 Interest paid ( 5,653 ) Interest expense recognized 3,749 Liability related to sale of future revenues - ending balance 55,163 Less: Current portion classified to accrued and other current liabilities ( 631 ) Liability related to sale of future revenues, non-current $ 54,532

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($) Segment
Accounting Policy [Line Items]
Number of reportable segment | Segment	1
Debt Financing Agreement [Member] | Minimum [Member]
Accounting Policy [Line Items]
Unrestricted cash and cash equivalent balance required to maintain in accounts | $	$ 30

Significant Accounting Polici_5

Significant Accounting Policies - Schedule of Weighted Impacts of Outstanding Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	19,431	13,532	18,210	12,489
Employee stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	15,072	9,701	13,792	8,857
RSUs, PRSUs and TSR awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	3,899	3,084	3,922	3,078
ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	460	747	496	554

Collaboration Agreements, Lic_3

Collaboration Agreements, License Agreement and Revenues - Astellas Agreements - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended			6 Months Ended
	Apr. 30, 2006	Jun. 30, 2005	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			$ 50,641,000	$ 44,319,000		$ 106,544,000	$ 80,480,000
Deferred Revenue			9,546,000			9,546,000		$ 12,740,000
Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			729,000	14,272,000		25,216,000	$ 16,381,000
Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price, variable consideration from estimated future co-development billing						$ 0
Japan [Member] | Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue				$ 14,400,000	$ 1,700,000
Astellas Agreement [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received		$ 172,600,000
Additional consideration based on net sales description						the low 20% range of the list price
Aggregate consideration received excluding drug product revenue			105,100,000			$ 105,100,000
Changes in revenue from changes to estimated variable consideration						$ 0
Astellas Agreement [Member] | Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received	$ 745,000,000
Additional consideration based on net sales description						low 20% range
Aggregate consideration received excluding drug product revenue			$ 685,000,000			$ 685,000,000
Percentage of joint development costs committed to fund	50%
Changes in revenue from changes to estimated variable consideration						$ 0

Collaboration Agreements, Lic_4

Collaboration Agreements, License Agreement and Revenues - AstraZeneca Agreements - Additional Information 1 (Detail) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
	Jul. 30, 2013	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Sep. 18, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		$ 50,641		$ 44,319		$ 106,544	$ 80,480
Deferred Revenue		9,546				9,546		$ 12,740
Drug product revenue recognized		50,641		44,319		106,544	80,480
Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		49,643		23,889		80,181	48,049
Drug product revenue recognized		49,643		23,889		80,181	48,049
Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		729		14,272		25,216	16,381
Drug product revenue recognized		729		14,272		25,216	16,381
Drug Product Revenue, Net [Member] | API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		400	$ 2,200	600
Drug product revenue recognized		400	$ 2,200	600
Japan [Member] | Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue				14,400	$ 1,700
Drug product revenue recognized				14,400	$ 1,700
AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized as Revenue						73,118
AstraZeneca Agreements [Member] | U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate considerations received						439,000
AstraZeneca Agreements [Member] | China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments	$ 376,700
Aggregate considerations received						77,200
Transaction price and allocated to performance obligations									$ 4,000
Contract asset		4,000				4,000
Direct Sales [Member] | Product [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		3,638		3,377		7,063	6,165
Drug product revenue recognized		$ 3,638		$ 3,377		$ 7,063	$ 6,165

Collaboration Agreements, Lic_5

Collaboration Agreements, License Agreement and Revenues - Summary of License Revenue and Development Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue	$ 50,641	$ 44,319	$ 106,544	$ 80,480
License Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenue	0	1,000	0	7,000
Development Revenue [Member]
Disaggregation of Revenue [Line Items]
Total revenue	269	5,158	1,147	9,050
Astellas Agreement [Member] | License Revenue [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Total revenue	318	1,806	606	3,335
AstraZeneca Agreements [Member] | Development Revenue [Member] | U.S./RoW and China [Member]
Disaggregation of Revenue [Line Items]
Total revenue	$ (50)	$ 2,273	$ 418	$ 4,305

Collaboration Agreements, Lic_6

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Astellas Agreement [Member] | Japan [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	$ 117,447
Astellas Agreement [Member] | Japan [Member] | Development Revenue [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	17,100
Astellas Agreement [Member] | Japan [Member] | License Revenue [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	100,347
Astellas Agreement [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	906,297
Astellas Agreement [Member] | Europe [Member] | Development Revenue [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	287,322
Astellas Agreement [Member] | Europe [Member] | License Revenue [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	618,975
AstraZeneca Agreements [Member]
Disaggregation of Revenue [Line Items]
Deferred Revenue	158,593	$ 179,851
AstraZeneca Agreements [Member] | China performance obligation [Member]
Disaggregation of Revenue [Line Items]
Deferred Revenue	158,600
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | License Revenue [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	344,500
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | Co-development, information sharing & committee services [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	625,500
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | China performance obligation [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	$ 427,500

Collaboration Agreements, Lic_7

Collaboration Agreements, License Agreement and Revenues - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail)	6 Months Ended
	Jun. 30, 2024 USD ($)
Europe [Member] | Astellas Agreement [Member]
Disaggregation of Revenue [Line Items]
Changes in revenue from changes to estimated variable consideration	$ 0
Total Consideration	906,297,000
Europe [Member] | Astellas Agreement [Member] | License [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	618,975,000
U.S./RoW and China [Member]
Disaggregation of Revenue [Line Items]
Changes in revenue from changes to estimated variable consideration	0
U.S./RoW and China [Member] | AstraZeneca Agreements [Member] | License [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	344,500,000
U.S./RoW and China [Member] | AstraZeneca Agreements [Member] | Co Development Information Sharing And Committee Services [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	625,500,000
U.S./RoW and China [Member] | AstraZeneca Agreements [Member] | China Performance Obligation [Member]
Disaggregation of Revenue [Line Items]
Total Consideration	427,500,000
U.S./RoW and China [Member] | AstraZeneca Agreements [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Cumulative Revenue	$ 268,900,000

Collaboration Agreements, Lic_8

Collaboration Agreements, License Agreement and Revenues - Summary of Product Revenue, Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation Of Revenue [Line Items]
Total revenue	$ 50,641	$ 44,319	$ 106,544	$ 80,480
Product Revenue, Net [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	49,643	23,889	80,181	48,049
Product Revenue, Net [Member] | Direct Sales [Member]
Disaggregation Of Revenue [Line Items]
Gross revenue	4,046	3,607	7,831	6,667
Total revenue	3,638	3,377	7,063	6,165
Product Revenue, Net [Member] | Direct Sales [Member] | Discounts and Rebates [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(408)	(229)	(767)	(503)
Product Revenue, Net [Member] | Direct Sales [Member] | Sales Returns [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0	(1)	(1)	1
Product Revenue, Net [Member] | Sales To Falikang [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	46,005	20,512	73,118	41,884
Gross transaction price	49,352	42,153	92,912	76,402
Product Revenue, Net [Member] | Sales To Falikang [Member] | Profit Share [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(21,397)	(18,312)	(40,420)	(33,300)
Product Revenue, Net [Member] | Sales To Falikang [Member] | Net Transfer Price [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	27,955	23,841	52,492	43,102
Product Revenue, Net [Member] | Sales To Falikang [Member] | Decrease (Increase) in Deferred Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 18,050	$ (3,329)	$ 20,626	$ (1,218)

Collaboration Agreements, Lic_9

Collaboration Agreements, License Agreement and Revenues - Product Revenue, Net - Additional Information 1 (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 50,641	$ 44,319	$ 106,544	$ 80,480
Contract with Customer, Liability [Abstract]
Deferred revenue, net of current	131,192		131,192		$ 157,555
Net unbilled milestone and co-development revenue	0		0		0
Constrained for Future Recognition [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	18,100	3,300	20,600	1,200
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	49,643	$ 23,889	80,181	$ 48,049
China [Member] | Product Revenue, Net [Member]
Contract with Customer, Liability [Abstract]
Contract with customer liability increase decrease in revenue due to changes to estimated variable consideration	12,200
AstraZeneca Agreements [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	158,593		158,593		179,851
Deferred revenue, net of current	131,300		131,300
Net unbilled milestone and co-development revenue	23,300		23,300		22,500
AstraZeneca Agreements [Member] | China performance obligation [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	158,600		158,600
Net unbilled milestone and co-development revenue	27,300		27,300
AstraZeneca Agreements [Member] | China [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	3,400		3,400
Beijing Falikang Pharmaceutical Co Ltd | Product Revenue, Net [Member]
Contract with Customer, Liability [Abstract]
Reductions to gross accounts receivable	$ 2,300		$ 2,300		$ 3,000

Collaboration Agreements, Li_10

Collaboration Agreements, License Agreement and Revenues - Roll-forward of Related Contract Liabilities (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
AstraZeneca Agreements [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2023	$ (179,851)
Additions	(53,269)
Currency Translation and Other	1,409
Recognized as Revenue	73,118
Balance at June 30, 2024	(158,593)
Drug Product Revenue, Net [Member] | Astellas Agreement [Member] | Europe [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2023	(16,925)
Reclassified to Accrued Liability	5,406
Recognized as Revenue	2,116
Balance at June 30, 2024	$ (9,403)

Collaboration Agreements, Li_11

Collaboration Agreements, License Agreement and Revenues - Drug Product Revenue - Summary of Drug Product Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 50,641	$ 44,319		$ 106,544	$ 80,480
Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	729	14,272		25,216	16,381
Drug Product Revenue, Net [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		14,400	$ 1,700
Drug Product Revenue, Net [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	700			500
Drug Product Revenue, Net [Member] | Astellas Agreement [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	(366)	13,809		(2,571)	15,541
Drug Product Revenue, Net [Member] | Astellas Agreement [Member] | Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,095	463		2,116	840
Drug Product Revenue, Net [Member] | AstraZeneca Agreements [Member] | U.S. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 0	$ 0		$ 25,671	$ 0

Collaboration Agreements, Li_12

Collaboration Agreements, License Agreement and Revenues - Drug Product Revenue - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended					6 Months Ended		12 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue	$ 9,546		$ 12,740			$ 9,546		$ 12,740
Drug product revenue recognized	50,641			$ 44,319		106,544	$ 80,480
Other long-term liabilities	1,012		2,858			1,012		2,858
Astra Zeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty revenue recognized as drug product revenue						73,118
Drug Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	729			14,272		25,216	16,381
Drug Product Revenue, Net [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	700					500
Drug Product Revenue, Net [Member] | Europe [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,095			463		2,116	840
Drug Product Revenue, Net [Member] | Europe [Member] | Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized						5,400
Collaboration agreement payment						35,300
Burdened manufacturing costs			800
Drug Product Revenue, Net [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized				14,400	$ 1,700
Drug Product Revenue, Net [Member] | Japan [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	(366)			13,809		(2,571)	15,541
Accrued liabilities	2,200		1,200			2,200		1,200
Other long-term liabilities	600		700			600		700
Drug Product Revenue, Net [Member] | API Shipment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	400	$ 2,200		600
Bulk Drug Product [Member] | Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue			17,700					17,700
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized								38,700
Accrued liabilities	8,800		$ 38,600			8,800		$ 38,600
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member] | Royalty Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty revenue recognized as drug product revenue	$ 1,100			$ 500		$ 2,100	$ 800

Collaboration Agreements, Li_13

Collaboration Agreements, License Agreement and Revenues - AstraZeneca U.S./RoW Agreement - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable from related parties	$ 6,412			$ 6,412		$ 12,553
Related cost of goods sold	$ 5,178		$ 5,708	$ 30,931	$ 9,199
AstraZeneca U.S./RoW Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cumulative catch-up net adjustment		$ 25,700
Related accounts receivable		26,000
Related accrued liabilities		11,500
Related cost of goods sold		$ 21,100

Collaboration Agreements, Li_14

Collaboration Agreements, License Agreement and Revenues - Eluminex Agreement - Additional Information 2 (Detail) - Eluminex [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jul. 31, 2021	Jun. 30, 2023	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2024	Dec. 31, 2023	Apr. 30, 2023
Revenue Recognition, Milestone Method [Line Items]
Aggregate consideration received for milestone and upfront payments	$ 8				$ 4	$ 4
Future manufacturing clinical regulatory and commercial milestone payments	64
Commercial milestone	$ 36
Additional upfront payments							$ 1.5
Upfront payment		$ 1
Cornea Products [Member]
Revenue Recognition, Milestone Method [Line Items]
Percentage of product manufacturing costs until manufacturing technology fully transferred				10%
China [Member] | Biosynthetic Cornea [Member]
Revenue Recognition, Milestone Method [Line Items]
Milestone Payments			$ 3
Manufacturing related milestone payments			$ 3

Collaboration Agreements, Li_15

Collaboration Agreements, License Agreement and Revenues - Summary of Amounts Recognized as Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue Recognition, Milestone Method [Line Items]
Total revenue	$ 50,641	$ 44,319	$ 106,544	$ 80,480
License Revenue [Member]
Revenue Recognition, Milestone Method [Line Items]
Total revenue	0	1,000	0	7,000
License Revenue [Member] | Eluminex [Member]
Revenue Recognition, Milestone Method [Line Items]
Total revenue	0	1,000	0	7,000
Other Revenue - Contract Manufacturing [Member]
Revenue Recognition, Milestone Method [Line Items]
Total revenue	269	5,158	1,147	9,050
Other Revenue - Contract Manufacturing [Member] | Eluminex [Member]
Revenue Recognition, Milestone Method [Line Items]
Total revenue	$ 0	$ 246	$ 116	$ 482

Variable Interest Entities - Co

Variable Interest Entities - Consolidated Variable Interest Entity - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
	May 05, 2023	Mar. 31, 2024	Jun. 30, 2024
Third Party Shareholders [Member] | Nonredeemable NCI [Member]
Business Acquisition [Line Items]
Ownership percentage	100%		100%
Other Investors [Member] | Nonredeemable NCI [Member]
Business Acquisition [Line Items]
Ownership percentage	98%		98%
Series A Preferred Shares [Member] | Nonredeemable NCI [Member]
Business Acquisition [Line Items]
Ownership percentage	2%		2%
Fortis Therapeutics [Member]
Business Acquisition [Line Items]
Payment to options exercised	$ 80
Contingent payment associated with business acquisition	200
Product development obligations	$ 5.4	$ 1.7

Variable Interest Entities - Eq

Variable Interest Entities - Equity Method Investment - Unconsolidated VIE - Additional Information (Detail)	Jun. 30, 2024
Beijing Kangda Yongfu Pharmaceutical Co., LTD [Member] | Beijing Falikang Pharmaceutical Co Ltd | FibroGen Beijing [Member] | AstraZenecaAB [Member]
Acquisition And Variable Interest Entity [Line Items]
Percentage of outstanding shares acquired	51.10%

Variable Interest Entities - _2

Variable Interest Entities - Equity Method Investment - Unconsolidated VIE - Summary of Equity Method Investment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Acquisition And Variable Interest Entity [Line Items]
Beginning balance			$ 5,290
Share of Net Income	$ 1,177	$ 550	1,766	$ 1,346
Ending balance	$ 6,912		$ 6,912
Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Ownership Percentage	51.10%		51.10%
Beginning balance			$ 5,290
Share of Net Income			1,766
Dividend Received			(144)
Ending balance	$ 6,912		$ 6,912

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		$ 121,898
Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		13,992
Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		52,273
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	$ 90,820	172,190
Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	11,080	12,288
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		13,992
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	52,869	88,289
Fair Value, Measurements, Recurring [Member] | U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	21,891	47,791
Fair Value, Measurements, Recurring [Member] | Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	4,980	9,830
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	28,988	55,085
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	11,080	12,288
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	17,908	42,797
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	61,832	117,105
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		13,992
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	52,869	88,289
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	3,983	4,994
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	4,980	9,830
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair value of U.S. treasury notes and bills transfered from level 1 to level 2		$ 26,300,000
Transfers of assets from level 1 to 2	$ 0
Transfers of assets from level 2 to 1	0
Transfers of assets into level 3	0
Transfers of assets out of level 3	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Cash	$ 49,894	$ 63,396
Commercial paper	52,869	36,016
Money market funds	11,080	12,288
U.S. government bonds	21,891	1,988
Agency bonds	4,980	0
Total cash and cash equivalents	$ 140,714	$ 113,688

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Jul. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 140,714,000		$ 140,714,000		$ 113,688,000
Impairment loss	0	$ 0	0	$ 0
API and bulk drug product price true-up	10,991,000		10,991,000		50,978,000
Accrued inventory related cost	8,521,000		8,521,000		0
Accrued litigation settlement	28,500,000		28,500,000		28,500,000
Net unbilled co-development revenue	0		0		0
Litigation settlement receivable	28,500,000		28,500,000		28,500,000
Short-term investments	0		0		121,898,000
Long-term investment	0		0
Eluminex Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate consideration received for milestone and upfront payments	4,000,000		4,000,000		4,000,000	$ 8,000,000
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Inventory write-down			12,600,000
Net unbilled co-development revenue	23,300,000		23,300,000		22,500,000
Payment to related parties	11,500,000
Astellas Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Payment to related parties	35,300,000
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 39,300,000		$ 39,300,000		$ 32,200,000

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 121,874
Gross Unrealized Holding Gains	30
Gross Unrealized Holding Losses	(6)
Estimated Fair Value	121,898
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,988
Gross Unrealized Holding Gains	9
Gross Unrealized Holding Losses	(5)
Estimated Fair Value	13,992
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52,273
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	52,273
U.S. government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	45,783
Gross Unrealized Holding Gains	20
Gross Unrealized Holding Losses	0
Estimated Fair Value	45,803
Agency bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,830
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	(1)
Estimated Fair Value	$ 9,830

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Available for Sale Securities in Unrealized Loss Position, Fair Value and Gross Unrealized Loss By Length of Time Security in Continual Unrealized Loss Position (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	$ 9,971
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(1)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	3,495
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(5)
Available for sale securities in continual unrealized loss position, estimated fair value	13,466
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(6)
Corporate bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	0
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	0
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	3,495
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(5)
Available for sale securities in continual unrealized loss position, estimated fair value	3,495
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(5)
U.S. government bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	4,984
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	0
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	0
Available for sale securities in continual unrealized loss position, estimated fair value	4,984
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	0
Agency bonds [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
Available for sale securities in continual unrealized loss position, less than 12 months, estimated fair value	4,987
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(1)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	0
Available for sale securities in continual unrealized loss position, estimated fair value	4,987
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	$ (1)

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Schedule of Investments [Abstract]
Raw materials	$ 1,018	$ 1,376
Work-in-progress	19,492	34,614
Finished goods	4,887	5,575
Total inventories	$ 25,397	$ 41,565

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Contract assets	$ 27,258	$ 26,481
Deferred revenues from associated contracts	(27,258)	(26,481)
Net contract assets	0	0
Insurance proceeds receivable for litigation settlement	28,500	28,500
Prepaid assets	4,846	6,644
Other current assets	3,590	6,711
Total prepaid expenses and other current assets	$ 36,936	$ 41,855

Balance Sheet Components - Sc_4

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Accrued Liabilities, Current [Abstract]
Preclinical and clinical trial accruals	$ 20,091	$ 27,663
API and bulk drug product price true-up	10,991	50,978
Litigation settlement	28,500	28,500
Payroll and related accruals	10,292	20,267
Inventory cost related	8,521	0
Accrued co-promotion expenses - current	13,209	10,309
Roxadustat profit share to AstraZeneca	6,909	7,084
Property taxes and other taxes	4,674	6,615
Professional services	5,616	7,103
Current portion of liability related to sale of future revenues	631	5,654
Accrued restructuring charge	0	3,697
Other	4,140	5,021
Total accrued and other current liabilities	$ 113,574	$ 172,891

Senior Secured Term Loan Faci_3

Senior Secured Term Loan Facilities - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Apr. 29, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt Instrument [Line Items]
Interest expense		$ 2.9	$ 1.7	$ 5.8	$ 1.7
Accrued interest		0.4		$ 0.4
Debt Financing Agreement [Member]
Debt Instrument [Line Items]
Interest rate per annum	14%
Maturity date	May 08, 2026
Repayment description				The Term Loans shall mature on May 8, 2026. The Term Loans will not be subject to amortization payments. The Company is permitted to prepay the Term Loans from time to time, in whole or in part, subject to payment of a make-whole amount equal to the unpaid principal amount of the portion of the Term Loans being repaid or prepaid, plus accrued and unpaid interest of the portion of the Term Loans being repaid or prepaid, plus an amount equal to the remaining scheduled interest payments due on such portion of the Term Loans being repaid or prepaid as if such Term Loans were to remain outstanding until the scheduled maturity date.
Debt Financing Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Unrestricted cash and cash equivalent balance required to maintain in accounts		30		$ 30
Initial Term Loan [Member]
Debt Instrument [Line Items]
Interest rate per annum				16.13%
Issuance costs and related transaction costs, amortised		$ 3.7		$ 3.7
Initial Term Loan [Member] | Debt Financing Agreement [Member]
Debt Instrument [Line Items]
Term loan	$ 75
Delayed Draw Term Loan [Member] | Debt Financing Agreement [Member]
Debt Instrument [Line Items]
Term loan	37.5
Delayed Draw Term Loan 2 | Debt Financing Agreement [Member]
Debt Instrument [Line Items]
Term loan	$ 37.5

Senior Secured Term Loan Faci_4

Senior Secured Term Loan Facilities - Summary of Senior Secured Term Loan Facilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Senior secured term loan facilities, non-current	$ 72,478	$ 71,934
Senior Secured Term Loan Facilities [Member]
Debt Instrument [Line Items]
Principal of senior secured term loan facilities	75,000
Less: Unamortized issuance costs and transaction costs	(2,522)
Senior secured term loan facilities, ending balance	72,478
Less: Current Portion classified to accrued and other current liabilities	0
Senior secured term loan facilities, non-current	$ 72,478

Liability Related to Sale of _3

Liability Related to Sale of Future Revenues - Additional Information (Detail) - USD ($)		3 Months Ended			6 Months Ended
	Nov. 04, 2022	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		$ 50,641,000		$ 44,319,000	$ 106,544,000	$ 80,480,000
Interest expense related to sale of future revenues					3,749,000
Interest paid			$ (5,700,000)		$ (5,653,000)
NovaQuest Capital Management [Member] | Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Effective annual interest rate related to sale of future revenues					15.63%
NovaQuest Capital Management [Member] | Revenue Interest Financing Agreement [Member] | Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Prepayment amount of 2024 to 2030	$ 80,000,000
NovaQuest Capital Management [Member] | Revenue Interest Financing Agreement [Member] | Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Prepayment amount of 2024 to 2030	125,000,000
NovaQuest Capital Management [Member] | Payment Period One [Member] | Revenue Interest Financing Agreement [Member] | Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment	62,500,000
NovaQuest Capital Management [Member] | Payment Cap Date on or before December 31, 2028 [Member] | Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount	100,000,000
NovaQuest Capital Management [Member] | Payment Cap Date on or after January 1, 2029 [Member] | Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount	112,500,000
NovaQuest Capital Management [Member] | Payment Cap Date after January 1, 2030 [Member] | Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum payment cap amount	125,000,000
NovaQuest Capital Management [Member] | Payment Period Two [Member] | Revenue Interest Financing Agreement [Member] | Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment	125,000,000
Product [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		49,643,000		23,889,000	$ 80,181,000	48,049,000
Product [Member] | NovaQuest Capital Management [Member] | Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payment	10,000,000
License [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		0		1,000,000	0	7,000,000
Other Revenue - Contract Manufacturing [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		269,000		5,158,000	1,147,000	9,050,000
Astellas Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future revenue granted	$ 50,000,000
Percentage of revenue interest on global net sales	100%
Astellas Agreement [Member] | Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue payment cap amount		125,000,000			125,000,000
Astellas Agreement [Member] | Product [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	22.50%
Astellas Agreement [Member] | Milestone payments [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	10%
Astellas Agreement [Member] | Milestone payments [Member] | Payment Period One [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of revenue sold	20%
Development Revenue [Member] | Astellas Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		300,000			600,000
Drug Product Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		729,000		14,272,000	25,216,000	16,381,000
Drug Product Revenue [Member] | Astellas Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		700,000			500,000
Non-cash interest expense related to drug product revenue		$ 1,700,000		$ 1,300,000	$ 3,700,000	$ 3,600,000

Liability Related to Sale of _4

Liability Related to Sale of Future Revenues - Schedule of Activities of Liability Related to Sale of Future Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2024	Jun. 30, 2024
Liability Related to Sale of Future Royalties [Abstract]
Liability related to sale of future revenues - beginning balance	$ 57,067	$ 57,067
Interest paid	$ (5,700)	(5,653)
Interest expense recognized		3,749
Liability related to sale of future revenues - ending balance		55,163
Less: Current portion classified to accrued and other current liabilities		(631)
Liability related to sale of future revenues, non-current		$ 54,532

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Accounts receivable from related parties	$ 6,412		$ 6,412		$ 12,553
Investment income	1,177	$ 550	1,766	$ 1,346
Equity method investments	6,912		6,912		5,290
Astellas [Member]
Related Party Transaction [Line Items]
Reduction of drug product revenue from related party	700	14,300	(500)	16,400
Due to related parties	11,600		11,600		40,500
Astellas [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties	300		300		800
Deferred Revenue	9,400		9,400		16,900
Falikang [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties	3,800		3,800		5,200
Investment income	1,200	600	1,800	1,300
Equity method investments	6,900		$ 6,900		$ 5,300
Percentage of outstanding shares owned			51.10%
Falikang [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenues	46,000	20,500	$ 73,100	41,900
License and Development [Member] | Astellas [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenues	$ 300	$ 1,800	$ 600	$ 3,500

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	2 Months Ended	6 Months Ended	32 Months Ended
	May 31, 2021 PutativeClassAction	Jun. 30, 2024 USD ($)	Apr. 03, 2024 ShareholderDerivative	Dec. 31, 2023 USD ($)	Oct. 17, 2023 USD ($)
Commitments And Contingencies [Line Items]
Operating lease liability		$ 73.9
Outstanding non-cancelable purchase obligations		19.7
Number of complaints filed	5		7
Litigation settlement amount				$ 28.5	$ 28.5
Manufacture and Supply of Roxadustat [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		0.8
Manufacture and Supply of Pamrevlumab [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		11.2
Other Purchases [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		7.6
Research and Preclinical Stage Development Programs [Member]
Commitments And Contingencies [Line Items]
Maximum future milestone payments		$ 697.9

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - Subsequent Event [Member]	Jul. 30, 2024 Patients
Subsequent Event [Line Items]
Number of LAPC patients	284
Restructuring plan, expected reduction to workforce, percentage	75%