FibroGen (FGEN) 10-Q 8 May 23 2023 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	Apr. 30, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN, INC.
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
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		97,582,416

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 188,550	$ 155,700
Short-term investments	167,399	266,308
Accounts receivable, net ($11,563 and $12,088 from related parties)	17,654	16,299
Inventories	42,456	40,436
Prepaid expenses and other current assets	14,490	14,083
Total current assets	430,549	492,826
Restricted time deposits	2,072	2,072
Long-term investments	0	4,348
Property and equipment, net	18,693	20,605
Equity method investment in unconsolidated variable interest entity	5,884	5,061
Operating lease right-of-use assets	76,674	79,893
Other assets	4,672	5,282
Total assets	538,544	610,087
Current liabilities:
Accounts payable ($57,499 and $0 to a related party)	71,282	30,758
Accrued and other current liabilities ($19,594 and $63,886 to a related party)	157,042	219,773
Deferred revenue ($13,129 and $9,259 to related parties)	16,495	12,739
Operating lease liabilities, current	9,927	10,292
Total current liabilities	254,746	273,562
Product development obligations	17,276	16,917
Deferred revenue, net of current	163,089	185,722
Operating lease liabilities, non-current	76,885	79,593
Liability related to sale of future revenues, non-current	48,370	49,333
Other long-term liabilities ($1,618 and $0 to a related party)	7,063	6,440
Total liabilities	567,429	611,567
Commitments and Contingencies (Note 10)
Stockholders' deficit:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at March 31, 2023 and December 31, 2022
Common stock, $0.01 par value; 225,000 shares authorized at March 31, 2023 and December 31, 2022; 96,623 and 94,166 shares issued and outstanding at March 31, 2023 and December 31, 2022	966	942
Additional paid-in capital	1,589,145	1,541,019
Accumulated other comprehensive loss	(4,570)	(5,720)
Accumulated deficit	(1,634,393)	(1,557,688)
Total stockholders' deficit	(48,852)	(21,447)
Non-controlling interests	19,967	19,967
Total deficit	(28,885)	(1,480)
Total liabilities, stockholders' deficit and non-controlling interests	$ 538,544	$ 610,087

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Accounts receivable from related parties	$ 11,563	$ 12,088
Accounts payable to related party	57,499	0
Accrued and other current liabilities to related party	19,594	63,886
Deferred revenue current to related party	13,129	9,259
Deferred revenue non-current to related party	10,245	31,044
Other long-term liabilities due to related party	$ 1,618	$ 0
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	96,623,000	94,166,000
Common stock, shares outstanding	96,623,000	94,166,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue:
Total revenue	$ 36,161	$ 60,827
Operating costs and expenses:
Cost of goods sold	$ 3,491	$ 4,238
Cost, Product and Service [Extensible List]	Product Revenue, Net [Member]	Product Revenue, Net [Member]
Research and development	$ 74,486	$ 89,018
Selling, general and administrative	34,275	30,564
Total operating costs and expenses	112,252	123,820
Loss from operations	(76,091)	(62,993)
Interest and other, net
Interest expense	(2,372)	(97)
Interest income and other income (expenses), net	1,036	(322)
Total interest and other, net	(1,336)	(419)
Loss before income taxes	(77,427)	(63,412)
Provision for income taxes	74	113
Investment income in unconsolidated variable interest entity	796	320
Net loss	$ (76,705)	$ (63,205)
Net income (loss) per share - basic	$ (0.81)	$ (0.68)
Net income (loss) per share - diluted	$ (0.81)	$ (0.68)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	94,691	93,043
Diluted	94,691	93,043
License Revenue [Member]
Revenue:
Total revenue	$ 6,000	$ 22,590
Development and Other Revenue [Member]
Revenue:
Total revenue	3,891	11,762
Product Revenue, Net [Member]
Revenue:
Total revenue	24,161	18,881
Drug Product Revenue [Member]
Revenue:
Total revenue	$ 2,109	$ 7,594

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
License and milestone revenue from a related party	$ 0	$ 22,590
Collaboration services and other revenue from a related party	1,624	5,180
Product revenue from a related party	21,372	16,223
Drug product revenue from a related party	$ 2,109	$ 7,594

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (76,705)	$ (63,205)
Other comprehensive income (loss):
Foreign currency translation adjustments	(248)	249
Available-for-sale investments:
Unrealized gain (loss) on investments, net of tax effect	1,398	(2,591)
Other comprehensive gain (loss), net of taxes	1,150	(2,342)
Comprehensive loss	$ (75,555)	$ (65,547)

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]
Balance at Dec. 31, 2021	$ 229,113	$ 929	$ 1,476,414	$ (4,163)	$ (1,264,034)	$ 19,967
Balance, Shares at Dec. 31, 2021		92,880,533
Net loss	(63,205)	$ 0	0	0	(63,205)	0
Change in unrealized gain or loss on investments	(2,591)	0	0	(2,591)	0	0
Foreign currency translation adjustments	249	0	0	249	0	0
Shares issued from stock plans, net of payroll taxes paid	(2,703)	$ 4	(2,707)	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		408,051
Stock-based compensation	17,152	$ 0	17,152	0	0	0
Balance at Mar. 31, 2022	178,015	$ 933	1,490,859	(6,505)	(1,327,239)	19,967
Balance, Shares at Mar. 31, 2022		93,288,584
Balance at Dec. 31, 2022	(1,480)	$ 942	1,541,019	(5,720)	(1,557,688)	19,967
Balance, Shares at Dec. 31, 2022		94,166,086
Net loss	(76,705)	$ 0	0	0	(76,705)	0
Change in unrealized gain or loss on investments	1,398	0	0	1,398	0	0
Foreign currency translation adjustments	(248)	0	0	(248)	0	0
Issuance of common stock under ATM Program	31,131	$ 15	31,116	0	0	0
Issuance of common stock under ATM Program shares		1,541,579
Shares issued from stock plans, net of payroll taxes paid	907	$ 9	898	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		915,644
Stock-based compensation	16,112	$ 0	16,112	0	0	0
Balance at Mar. 31, 2023	$ (28,885)	$ 966	$ 1,589,145	$ (4,570)	$ (1,634,393)	$ 19,967
Balance, Shares at Mar. 31, 2023		96,623,309

Condensed Consolidated Statem_5

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities
Net loss	$ (76,705)	$ (63,205)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	2,542	2,450
Amortization of finance lease right-of-use assets	423	134
Net accretion of premium and discount on investments	(689)	928
Investment income in unconsolidated variable interest entity	(796)	(320)
Loss on disposal of property and equipment	1	5
Stock-based compensation	16,112	17,152
Non-cash interest expense related to sale of future revenues	2,249	0
Impairment of investment	1,000	0
Realized loss on sales of available-for-sale securities	271	5
Changes in operating assets and liabilities:
Accounts receivable, net	(1,299)	(26,481)
Inventories	(1,940)	(12,000)
Prepaid expenses and other current assets	38	11,382
Operating lease right-of-use assets	3,237	3,132
Other assets	1,072	(459)
Accounts payable	40,473	10,207
Accrued and other liabilities	(66,266)	65,993
Operating lease liabilities, current	(371)	31
Deferred revenue	(18,877)	(13,024)
Accrued interest for finance lease liabilities	(56)	(21)
Operating lease liabilities, non-current	(2,720)	(2,835)
Other long-term liabilities	710	(1,550)
Net cash used in operating activities	(101,591)	(8,476)
Investing activities
Purchases of property and equipment	(591)	(1,638)
Payment made for acquired in-process research and development asset	0	(35,000)
Purchases of available-for-sale securities	(2,472)	(20,912)
Proceeds from sales of available-for-sale securities	1,730	7,382
Proceeds from maturities of investments	104,815	76,103
Net cash provided by investing activities	103,482	25,935
Financing activities
Repayments of finance lease liabilities	(71)	(1)
Repayments of lease obligations	(101)	(101)
Cash paid for payroll taxes on restricted stock unit releases	0	(2,974)
Proceeds from issuance of common stock under ATM Program, net of commissions	30,750	0
Proceeds from issuance of common stock under employee stock plans	907	183
Net cash provided by (used in) financing activities	31,485	(2,893)
Effect of exchange rate change on cash and cash equivalents	(526)	107
Net increase in cash and cash equivalents	32,850	14,673
Total cash and cash equivalents at beginning of period	155,700	171,223
Total cash and cash equivalents at end of period	$ 188,550	$ 185,896

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2023
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 a leading biopharmaceutical company discovering, developing and commercializing a pipeline of first-in-class therapeutics. The Company applies its pioneering expertise in hypoxia-inducible factor (“HIF”) biology, 2-oxoglutarate enzymology, and connective tissue growth factor to advance innovative medicines for the treatment of anemia, fibrotic disease, and cancer. Pamrevlumab, a human monoclonal antibody targeting connective tissue growth factor, is in Phase 3 clinical development for the treatment of idiopathic pulmonary fibrosis, locally advanced unresectable pancreatic cancer and Duchenne muscular dystrophy. To date, the Company has retained exclusive worldwide rights for pamrevlumab. Roxadustat is an oral small molecule inhibitor of HIF 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 Phase 3 clinical development for anemia associated with myelodysplastic syndromes, in the United States (“U.S.”) and Europe, and chemotherapy-induced anemia in China. The Company has a pipeline of late-stage clinical programs as well as preclinical drug candidates at various stages of development that include both small molecules and biologics. FibroGen’s goal is to build a diversified pipeline with novel drugs that will address unmet patient needs in oncology, immunology, and fibrosis. 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, FibroGen Europe Oy and FibroGen China Anemia Holdings, Ltd. All inter-company transactions and balances have been eliminated in consolidation. For any variable interest entity (“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 U.S. (“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 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, 2022 , filed on February 27, 2023 (“2022 Form 10-K”). 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 2022 Form 10-K. 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 the three months ended March 31, 2023 and 2022. 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 March 31, 2023 2022 Employee stock options 7,578 9,484 RSUs, PRSUs and TSR awards 2,762 2,196 ESPP 362 473 10,702 12,153 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.

Collaboration Agreements, Licen

Collaboration Agreements, License Agreement and Revenues	3 Months Ended
	Mar. 31, 2023
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 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 March 31, 2023 totaled $ 105.1 million , excluding drug product revenue that is discussed under the Drug Product Revenue section below. Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Astellas Japan Agreement License revenue $ — $ — Development revenue $ 95 $ 32 The transaction price related to consideration received through March 31, 2023 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 16,977 Total license and development revenue $ 117,324 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 March 31, 2023 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 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 . On March 21, 2022, EVRENZO ® (roxadustat) was registered with the Russian Ministry of Health. The Company evaluated the regulatory milestone payment associated with the approval in Russia under the Astellas Europe Agreement and concluded that this milestone was achieved in the first quarter of 2022. Accordingly, the consideration of $ 25.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Astellas Europe Agreement, all of which was recognized as revenue during the first quarter of 2022 from performance obligations satisfied. The aggregate amount of consideration received under the Astellas Europe Agreement through March 31, 2023 totaled $ 685.0 million , excluding drug product revenue that is discussed under the Drug Product Revenue section below. Amounts recognized as license revenue and development revenue under the Astellas Europe Agreement were as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Astellas Europe Agreement License revenue $ — $ 22,590 Development revenue $ 1,529 $ 5,148 The transaction price related to consideration received through March 31, 2023 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 281,794 Total license and development revenue $ 900,769 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 March 31, 2023 under the Astellas Europe Agreement. The remainder of the transaction price related to the Astellas Europe Agreement includes $ 5.8 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period. Under the Astellas Europe Agreement, Astellas has an option to purchase roxadustat bulk drug product in support of commercial supplies. During the first quarter of 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 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”). It also excludes China, which is covered by a separate agreement with AstraZeneca described below. Under the terms of the AstraZeneca U.S./RoW Agreement, AstraZeneca agreed to pay upfront, non-contingent, non-refundable and time-based payments, and potential milestone payments, totaling $ 1.2 billion . AstraZeneca commits to pay the Comp any tiered royalty payments on AstraZeneca’s future net sales (as defined in the agreement) of roxadustat in the low 20% range . In addition, the Company is entitled to receive a transfer price for shipment of commercial product based on a percentage of AstraZeneca’s net sales (as defined in the agreement) in the low- to mid-single digit range. The aggregate amount of consideration received under the AstraZeneca U.S./RoW Agreement through March 31, 2023 totaled $ 439.0 million , excluding drug product revenue that is discussed separately below. While FibroGen and AstraZeneca continue to develop roxadustat in the U.S. for the treatment of anemia in patients with myelodysplastic syndromes, the Company has not been able to agree on a path forward for AstraZeneca to fund further roxadustat development for chronic kidney disease anemia in the U.S. Therefore, the Company does not expect to receive most or all of the remaining AstraZeneca U.S./RoW Agreement milestones from AstraZeneca. In 2020, the Company entered into a Master Supply Agreement with AstraZeneca under the AstraZeneca U.S./RoW Agreement (“AstraZeneca Master Supply Agreement”) to define general forecast, order, supply and payment terms for AstraZeneca 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 section below. AstraZeneca China Agreement Effective July 30, 2013, the Company (through its subsidiaries affiliated with China) entered into a collaboration agreement with AztraZeneca 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 March 31, 2023 totaled $ 77.2 million . AstraZeneca China Amendment In July 2020, FibroGen China Anemia Holdings, Ltd., FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), and FibroGen International (Hong Kong) Limited and AstraZeneca entered into an amendment to the AstraZeneca China Amendment, 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. 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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement License revenue $ — $ — Development revenue 2,032 5,819 The transaction price relat ed to consideration received through March 31, 2023 and accounts receivable has been allocated to each of the following performance obligations under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, along with any associated deferred revenue as follows (in thousands): AstraZeneca U.S./RoW Agreement and Cumulative Revenue Deferred Revenue at Total Consideration License $ 341,844 $ — $ 341,844 Co-development, information sharing & 617,670 — 617,670 China performance obligation * 128,106 175,326 303,432 Total license and development revenue $ 1,087,620 $ 175,326 ** $ 1,262,946 * China performance obligation revenue is recognized as product revenue, as described under Product Revenue, Net section below. ** Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the consolidated balance sheets. As of March 31, 2023, deferred revenue included $ 156.2 million related to the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, which represents the net of $ 175.3 million of deferred revenue presented above and a $ 19.1 million unbilled co-development revenue under the AstraZeneca China Amendment. 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 March 31, 2023 under the AstraZeneca U.S./RoW Agreement. The remainder of the transaction price related to the AstraZeneca U.S./R oW Agreement and AstraZeneca China Agreement includes $ 9.8 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period, except for amounts allocated to the China performance obligation. The amount allocated to the China performance obligation is expected to be recognized as the Company transfers control of the commercial drug product to Falikang, and is expected to continue through 2028, which reflects our best estimates. 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. Product Revenue, Net Product revenue, net from the sales of roxadustat commercial product in China was as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Direct Sales: Gross revenue $ 3,060 $ 2,830 Discounts and rebates ( 273 ) ( 175 ) Sales returns 2 3 Direct sales revenue, net 2,789 2,658 Sales to Falikang: Gross transaction price 34,249 22,726 Profit share ( 14,988 ) ( 8,849 ) Net transaction price 19,261 13,877 Decrease in deferred revenue 2,111 2,346 Sales to Falikang revenue, net 21,372 16,223 Total product revenue, net $ 24,161 $ 18,881 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 calculated at the individual distributor level. The contract liabilities were included in accrued and other current liabilities in the condensed consolidated balance sheet and were immaterial as of March 31, 2023 and December 31, 2022, respectively. The rebates and discounts reflected as reductions to gross accounts receivable for direct sales were immaterial as of March 31, 2023 and December 31, 2022, 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 transfer 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. 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 total sales quantity, performance period and other inputs including foreign currency translation impact, among others. Following updates to its estimates, the Company recognized $ 2.1 million and $ 2.3 million from the previously deferred revenue of the China performance obligation during the three months ended March 31, 2023 and 2022, respectively. The product revenue recognized for the three months ended March 31, 2023 included a decrease in revenue of $ 0.3 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied in previous periods. 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 $ ( 175,646 ) $ ( 20,889 ) $ 21,372 $ ( 163 ) $ ( 175,326 ) 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. As of March 31, 2023 , approximately $ 22.5 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 $ 2.2 million and $ 0.5 million as of March 31, 2023 and December 31, 2022 , respectively. 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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Astellas Japan Agreement $ 1,732 $ 7,594 Astellas Europe Agreement 377 — Drug product revenue $ 2,109 $ 7,594 Astellas Japan Agreement 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 adjustments 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. During the three months ended March 31, 2022, the Company fulfilled a shipment obligation under the terms of Astellas Japan Amendment, and recognized related drug product revenue of $ 9.8 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 recorded a reduction to the drug product revenue of $ 2.2 million during the first quarter of 2022. 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, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others. As of March 31, 2023, t he balances related to the API price true-up under the Astellas Japan Agreement were $ 3.2 million in accrued liabilities and $ 1.6 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, 2022, the related balance in accrued liabilities was $ 6.5 million. 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, and 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. During the first quarter of 2022, 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, the Company reclassified the related deferred revenue to accrued liabilities during the year ended December 31, 2022. As of December 31, 2022, the related balance was $ 57.4 million in accrued liabilities. Further during the three months ended March 31, 2023 , the Company reclassified $ 16.6 million from the related deferred revenue to accrued liabilities. As of March 31, 2023, the balances related to the bulk drug product price true-up under the Astellas Europe Agreement and the Astellas EU Supply Agreement were $ 57.5 million in accounts payable and $ 16.4 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 $ 0.4 million as drug product revenue from the deferred revenue under the Astellas Europe Agreement during the three months ended March 31, 2023. 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 Additions Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 40,303 ) $ — $ 377 $ 16,552 $ ( 23,374 ) AstraZeneca U.S./RoW Agreement There was no shipment of bulk drug product to AstraZeneca as commercial supply under the terms of the AstraZeneca Master Supply Agreement during the three months ended March 31, 2023 and 2022. During the first quarter of 2022, the Company evaluated the current developments in the U.S. market, and updated its estimates of variable consideration associated with bulk drug product shipments to AstraZeneca in prior years as commercial supply. As a result, the Company reclassified $ 11.2 million from the related deferred revenue to accrued liabilities during the year ended December 31, 2022. As of each of March 31, 2023 and December 31, 2022, the related balance in accrued liabilities was $ 11.2 million, representing the Company’s best estimate that this amount will be paid within the next 12 months . 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, Eluminex made an $ 8.0 million upfront payment to FibroGen during the first quarter of 2022, which was recognized as license revenue for the performance obligation satisfied during 2021 . 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 n et sales of other recombinant human collagen type III products that are not cornea products. During the three months ended March 31, 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 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 . The related contract manufacturing revenue was recorded as other revenue and included in development and other revenue in the condensed consolidated statement of operations. Amounts recognized as revenue under the Eluminex were as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Eluminex License revenue $ 6,000 $ — Other revenue - contract manufacturing $ 235 $ 762

Equity method investment - Vari

Equity method investment - Variable Interest Entity	3 Months Ended
	Mar. 31, 2023
Acquisition And Variable Interest Entity [Abstract]
Equity method investment - Variable Interest Entity	3. Equity method investment - Variable Interest Entity 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, Consolidation (“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 has 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 % $ 5,061 $ 796 $ 27 $ 5,884 Falikang is considered a related party to the Company. See Note 9, Related Party Transactions , for related disclosures.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2023
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): March 31, 2023 Level 1 Level 2 Level 3 Total Money market funds $ 42,740 $ — $ — $ 42,740 Corporate bonds — 41,304 — 41,304 Commercial paper — 42,970 — 42,970 U.S. government bonds 57,141 14,425 — 71,566 Agency bonds — 9,075 — 9,075 Asset-backed securities — 2,484 — 2,484 Total $ 99,881 $ 110,258 $ — $ 210,139 December 31, 2022 Level 1 Level 2 Level 3 Total Money market funds $ 19,881 $ — $ — $ 19,881 Corporate bonds — 82,008 — 82,008 Commercial paper — 57,381 — 57,381 U.S. government bonds 98,972 12,373 — 111,345 Agency bonds — 11,468 — 11,468 Asset-backed securities — 2,474 — 2,474 Foreign government bonds — 4,980 — 4,980 Convertible promissory note — — 1,000 1,000 Total $ 118,853 $ 170,684 $ 1,000 $ 290,537 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. During the three months ended March 31, 2023 , a total of $ 7.0 million of US 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	3 Months Ended
	Mar. 31, 2023
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): March 31, 2023 December 31, 2022 Cash $ 145,810 $ 135,819 Money market funds 42,740 19,881 Total cash and cash equivalents $ 188,550 $ 155,700 At March 31, 2023 and December 31, 2022, a total of $ 98.9 million and $ 92.5 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’s investments consist primarily of available-for-sale debt investments. 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): March 31, 2023 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 41,760 $ 1 $ ( 457 ) $ 41,304 Commercial paper 42,970 — — 42,970 U.S. government bonds 72,130 1 ( 565 ) 71,566 Agency bonds 9,183 — ( 108 ) 9,075 Asset-backed securities 2,491 — ( 7 ) 2,484 Total investments $ 168,534 $ 2 $ ( 1,137 ) $ 167,399 December 31, 2022 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 83,080 $ — $ ( 1,072 ) $ 82,008 Commercial paper 57,381 — — 57,381 U.S. government bonds 112,547 5 ( 1,207 ) 111,345 Agency bonds 11,690 — ( 222 ) 11,468 Asset-backed securities 2,484 — ( 10 ) 2,474 Foreign government bonds 5,007 — ( 27 ) 4,980 Convertible promissory note 1,000 — — 1,000 Total investments $ 273,189 $ 5 $ ( 2,538 ) $ 270,656 The following table summarizes, for all available for sale securities in an unrealized loss position, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position (in thousands): March 31, 2023 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ 2,469 $ ( 7 ) $ 36,084 $ ( 450 ) $ 38,553 $ ( 457 ) U.S. government bonds 4,955 ( 1 ) 43,794 ( 564 ) 48,749 ( 565 ) Agency bonds — — 9,075 ( 108 ) 9,075 ( 108 ) Asset-backed securities 2,483 ( 7 ) — — 2,483 ( 7 ) Total $ 9,907 $ ( 15 ) $ 88,953 $ ( 1,122 ) $ 98,860 $ ( 1,137 ) December 31, 2022 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ 6,738 $ ( 147 ) $ 75,270 $ ( 925 ) $ 82,008 $ ( 1,072 ) U.S. government bonds 22,326 ( 13 ) 67,909 ( 1,194 ) 90,235 ( 1,207 ) Agency bonds — — 11,468 ( 222 ) 11,468 ( 222 ) Asset-backed securities 2,474 ( 10 ) — — 2,474 ( 10 ) Foreign government bonds - — 4,980 ( 27 ) 4,980 ( 27 ) Total $ 31,538 $ ( 170 ) $ 159,627 $ ( 2,368 ) $ 191,165 $ ( 2,538 ) At March 31, 2023, the available-for-sale investments had remaining contractual maturities of less than twelve months. The Company periodically reviews its available-for-sale investments for other-than-temporary impairment. The Company considers factors such as the duration, 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 other-than-temporary impairment loss during the three months ended March 31, 2023 and 2022. Inventories Inventories consisted of the following (in thousands): March 31, 2023 December 31, 2022 Raw materials $ 1,226 $ 1,241 Work-in-progress $ 37,273 36,003 Finished goods $ 3,957 3,192 Total inventories $ 42,456 $ 40,436 Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): March 31, 2023 December 31, 2022 Preclinical and clinical trial accruals $ 42,953 $ 57,780 API and bulk drug product price true-up 30,758 75,055 Payroll and related accruals 12,230 22,562 Accrued co-promotion expenses - current 36,688 36,677 Roxadustat profit share to AstraZeneca 7,311 7,280 Property taxes and other taxes 8,041 7,691 Professional services 8,354 5,480 Current portion of liability related to sale of future revenues 3,212 — Other 7,495 7,248 Total accrued and other current liabilities $ 157,042 $ 219,773 The accrued liabilities of $ 30.8 million for API and bulk drug product price true-up as of March 31, 2023 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. See the Drug Product Revenue section in Note 2, Collaboration Agreements, License Agreement and Revenues, for details.

Liability Related to Sale of Fu

Liability Related to Sale of Future Revenues	3 Months Ended
	Mar. 31, 2023
Liability Related to Sale of Future Royalties [Abstract]
Liability Related to Sale of Future Revenues	6. 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 19.64 % for the three months ended March 31, 2023. The following table summarizes the activity of the liability related to sale of future revenues for the three months ended March 31, 2023: Three Months Ended Liability related to sale of future revenues - beginning balance $ 49,333 Interest expense recognized 2,249 Liability related to sale of future revenues - ending balance 51,582 Less: Current portion classified to accrued and other current liabilities ( 3,212 ) Liability related to sale of future revenues, non-current $ 48,370 During the three months ended March 31, 2023 , the Company recognized, under Astellas Agreements, development revenue of $ 1.6 million and drug product revenue of $ 2.1 million. See Note 2, Collaboration Agreements, License Agreement and Revenue , for details. During the three months ended March 31, 2023 , the Company recognized the related non-cash interest expense of $ 2.2 million. 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 to reach a Payment Cap up to $ 125.0 million by 2031.

At-the-Market Program

At-the-Market Program	3 Months Ended
	Mar. 31, 2023
Stockholders' Equity Note [Abstract]
At-the-Market Program	7. At-the-Market Program On February 27, 2023, the Company entered into an Amended and Restated Equity Distribution Agreement (the “at-the-market agreement”) with Goldman Sachs & Co., LLC and BofA Securities, Inc. (each a “Sales Agent”), which amended and restated its Equity Distribution Agreement with Goldman Sachs & Co., LLC, dated August 8, 2022, to add BofA Securities, Inc. as an additional Sales Agent under that agreement. Under the at-the-market agreement, the Company may issue and sell, from time to time and through the Sales Agents, shares of its common stock having an aggregate offering price of up to $ 200.0 million (the “ATM Program”). For the three months ended March 31, 2023 , the Company sold 1,541,579 shares under the ATM Program, for approximately $ 31.1 million, net of commissions to Sales Agents, at a weighted-average offering prices per share of $ 20.25 , of which $ 30.8 million was received in cash during the same period. The remainder of the net proceeds was recorded as other receivables and included in prepaid expenses and other current assets in the condensed consolidated balance sheet as of March 31, 2023 and received in April 2023.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes Provisions for income tax for the three months ended March 31, 2023 and 2022 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	3 Months Ended
	Mar. 31, 2023
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 $ 1.6 million and $ 27.8 million for the three months ended March 31, 2023 and 2022 , respectively. The Company also recorded drug product revenue from Astellas of $ 2.1 million and $ 7.6 million for the three months ended March 31, 2023 and 2022, 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 months ended March 31, 2023 and 2022. As of March 31, 2023 and December 31, 2022 , accounts receivable from Astellas were $ 1.6 million and $ 1.5 million, respectively. As of March 31, 2023 and December 31, 2022 , total deferred revenue from Astellas was $ 23.4 million and $ 40.3 million, respectively. As of March 31, 2023, the amounts due to Astellas, included in accounts payable, accrued and other current liabilities, and other long-term liabilities, totaled $ 78.7 million. As of December 31, 2022 , the amount due to Astellas, included in accrued and other current liabilities, was $ 63.9 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 Note 3, Equity method investment - Variable Interest Entity , for details. The net product revenue from Falikang was $ 21.4 million and $ 16.2 million for the three months ended March 31, 2023 and 2022, respectively. See the Product Revenue, Net section in Note 2, Collaboration Agreements, License Agreement and Revenues , for details. The investment income in Falikang was $ 0.8 million and $ 0.3 million for the three months ended March 31, 2023 and 2022, respectively. As of March 31, 2023 and December 31, 2022, the Company’s equity method investment in Falikang was $ 5.9 million and $ 5.1 million , respectively. See Note 3, Variable Interest Entity , for details. The other income from Falikang was immaterial for each of the three months ended March 31, 2023 and 2022. As of March 31, 2023 and December 31, 2022 , accounts receivable, net, from Falikang, were $ 9.9 million and $ 10.5 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Contract Obligations As of March 31, 2023 , the Company had outstanding total non-cancelable purchase obligations of $ 51.9 million, including $ 22.4 million for manufacture and supply of pamrevlumab, $ 4.1 million for manufacture and supply of roxadustat, and $ 25.4 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 March 31, 2023 , 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 (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 March 31, 2023, the Company had $ 86.8 million of operating lease liabilities. In addition, see Note 6, Liability Related to Sale of Future Revenues for details of the related obligation. 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 in its condensed consolidated balance sheet as of March 31, 2023, 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. Plaintiffs filed their consolidated amended complaint on October 29, 2021 and a corrected consolidated amended complaint on November 19, 2021 (the “Complaint”). The Complaint alleges false and misleading statements between December 2018 and June 2021 and seeks to represent a class of persons or entities that purchased FibroGen securities between December 20, 2018 and July 15, 2021. On July 15, 2022, the court issued an order denying Defendants’ motions to dismiss. Defendants answered the Complaint on September 13, 2022 and discovery is ongoing. On January 27, 2023, Plaintiffs filed a motion for class certification. Defendants’ opposition to the motion for class certification is due May 12, 2023. On July 30, 2021, a purported shareholder derivative (the “California Federal Derivative”) complaint was filed in the U.S. District Court for the Northern District of California. The California Federal Derivative complaint names as defendants FibroGen’s current and former officers and directors, as well as FibroGen as nominal defendant, and asserts state and federal claims based on some of the same alleged misstatements as the securities class action complaint. The California Federal Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. On December 27, 2021, a second purported shareholder derivative (the “Delaware Federal Derivative”) complaint was filed in the U.S. District Court for the District of Delaware. The Delaware Federal Derivative complaint names FibroGen’s current and former officers and directors as defendants, as well as FibroGen as nominal defendant, and asserts state and federal claims based on some of the same alleged misstatements as the securities class action complaint, as well as allegations of insider trading against certain defendants. The Delaware Federal Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. On April 14, 2022, a third purported shareholder derivative (the “Delaware Chancery Derivative”) complaint was filed in the Delaware Court of Chancery. The Delaware Chancery Derivative complaint names substantially the same defendants as the other purported shareholder derivative actions and asserts similar claims based upon similar allegations. The Delaware Chancery Derivative complaint seeks unspecified damages, attorneys’ fees, and other costs. All three derivative actions have been stayed pending resolution of any motions for summary judgment in the securities class action. The Company believes that the claims 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 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 August 3, 2022 and August 4, 2022, the Company’s Board of Directors received three 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. On March 27, 2023, the Company’s Board of Directors received another litigation demand from a purported shareholder of the Company, seeking similar action as the other litigation demands. 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 has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these arrangements is minimal.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event Debt Financing Agreement On April 29, 2023, FibroGen 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 (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 (i) shall fund the Initial Term Loan by May 8, 2023, (ii) shall fund the Delayed Draw Term Loan 1 within 24 business days from the date of achievement of certain clinical development milestones but no later than August 31, 2023 and, (iii) at their discretion, shall provide Delayed Draw Term Loan 2 on or prior to August 31, 2023, whether or not such clinical development milestones are achieved. The Term Loans shall accrue interest at a 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. During the term of the Term Loans, the Company is required to maintain a minimum balance of $ 30.0 million of unrestricted cash and cash equivalents held in accounts in the United States, tested monthly on each interest payment date (after netting the monthly interest payment then due). In addition, while any portion of the Term Loans or any other obligations under the Financing Agreement remain outstanding, the Company must comply with certain customary affirmative and negative covenants set forth in the Financing Agreement and related loan documents, including, without limitation, restrictions or limitations on: incurrence of further indebtedness or liens, acquisitions and other investments, breach or material default under certain material contracts, dividends, distributions and stock buy-backs, negative pledges, sales, transfers, licenses or other disposition of assets (including core intellectual property), prepayment of other indebtedness, and transactions with affiliates, in each case, subject to thresholds and exceptions set forth in the Financing Agreement and related loan documents. The Financing Agreement provides for customary events of default triggers, including, without limitation, non-payment, breach of covenants (including the minimum cash covenant described above), material misrepresentation, cross-default to other material indebtedness of the Company or its subsidiaries (or the imposition of a material event of default fee or similar payment under a royalty monetization transaction), commencement of voluntary or involuntary bankruptcy proceedings, material judgments, change of control, invalidity of loan documents, certain ERISA events, certain regulatory events and failure to draw any portion of the Delayed Draw Term Loan 1 when funded by the Lenders. Upon an event of default, the Administrative Agent may, and at the direction of the majority Lenders shall, accelerate all outstanding obligations of the Company under the Financing Agreement and related loan documents, terminate all outstanding funding commitments and/or exercise remedies available at law or equity or under contract for secured creditors. The Term Loans and all other obligations of the Company under the Financing Agreement and related loan documents are guaranteed by each of the Company’s current and future, direct and indirect, subsidiaries, with certain exceptions (including an exclusion for any Chinese subsidiary of the Company). The Term Loans are secured by substantially all assets of the Company and the guarantors, subject to customary exceptions. Exclusive License and Option to Acquire Fortis Therapeutics On May 5, 2023, the Company entered into an exclusive option agreement to acquire Fortis Therapeutics (“Fortis”) with its novel Phase 1 antibody-drug conjugate, FOR46, that targets a novel epitope on CD46 preferentially expressed on certain cancer cells. FOR46 is in development for the treatment of metastatic castration-resistant prostate cancer with potential applicability in other solid tumors and hematologic malignancies. Pursuant to an evaluation agreement entered into with Fortis concurrent with the option agreement, FibroGen has exclusively licensed FOR46 and will control and fund future research, development, including a Phase 2 clinical study sponsored by FibroGen, and manufacturing of FOR46 during the 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 (“PET46”) for patient selection. FibroGen will pay Fortis $ 5.0 million during the four-year option period in support of their continued development obligations. If FibroGen exercises the option to acquire Fortis, it will pay Fortis $ 80.0 million, and thereafter, Fortis 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 UCSF, an upstream licensor to Fortis, development milestone fees and a single digit royalty on net sales of therapeutic or diagnostic products arising from the collaboration. If FibroGen chooses not to acquire Fortis, its exclusive license to FOR46 would expire.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2023
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 a leading biopharmaceutical company discovering, developing and commercializing a pipeline of first-in-class therapeutics. The Company applies its pioneering expertise in hypoxia-inducible factor (“HIF”) biology, 2-oxoglutarate enzymology, and connective tissue growth factor to advance innovative medicines for the treatment of anemia, fibrotic disease, and cancer. Pamrevlumab, a human monoclonal antibody targeting connective tissue growth factor, is in Phase 3 clinical development for the treatment of idiopathic pulmonary fibrosis, locally advanced unresectable pancreatic cancer and Duchenne muscular dystrophy. To date, the Company has retained exclusive worldwide rights for pamrevlumab. Roxadustat is an oral small molecule inhibitor of HIF 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 Phase 3 clinical development for anemia associated with myelodysplastic syndromes, in the United States (“U.S.”) and Europe, and chemotherapy-induced anemia in China. The Company has a pipeline of late-stage clinical programs as well as preclinical drug candidates at various stages of development that include both small molecules and biologics. FibroGen’s goal is to build a diversified pipeline with novel drugs that will address unmet patient needs in oncology, immunology, and fibrosis.
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, FibroGen Europe Oy and FibroGen China Anemia Holdings, Ltd. All inter-company transactions and balances have been eliminated in consolidation. For any variable interest entity (“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 U.S. (“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 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, 2022 , filed on February 27, 2023 (“2022 Form 10-K”).
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 the three months ended March 31, 2023 and 2022. 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 March 31, 2023 2022 Employee stock options 7,578 9,484 RSUs, PRSUs and TSR awards 2,762 2,196 ESPP 362 473 10,702 12,153
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.
Collaboration Agreements, License Agreement and Revenues	Astellas Agreements Astellas Japan Agreement In June 2005, the Company entered into a collaboration agreement with 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 March 31, 2023 totaled $ 105.1 million , excluding drug product revenue that is discussed under the Drug Product Revenue section below.
Product Revenue, Net	Product Revenue, Net Product revenue, net from the sales of roxadustat commercial product in China was as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Direct Sales: Gross revenue $ 3,060 $ 2,830 Discounts and rebates ( 273 ) ( 175 ) Sales returns 2 3 Direct sales revenue, net 2,789 2,658 Sales to Falikang: Gross transaction price 34,249 22,726 Profit share ( 14,988 ) ( 8,849 ) Net transaction price 19,261 13,877 Decrease in deferred revenue 2,111 2,346 Sales to Falikang revenue, net 21,372 16,223 Total product revenue, net $ 24,161 $ 18,881 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 calculated at the individual distributor level. The contract liabilities were included in accrued and other current liabilities in the condensed consolidated balance sheet and were immaterial as of March 31, 2023 and December 31, 2022, respectively. The rebates and discounts reflected as reductions to gross accounts receivable for direct sales were immaterial as of March 31, 2023 and December 31, 2022, 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 transfer 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. 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 total sales quantity, performance period and other inputs including foreign currency translation impact, among others. Following updates to its estimates, the Company recognized $ 2.1 million and $ 2.3 million from the previously deferred revenue of the China performance obligation during the three months ended March 31, 2023 and 2022, respectively. The product revenue recognized for the three months ended March 31, 2023 included a decrease in revenue of $ 0.3 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied in previous periods. 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 $ ( 175,646 ) $ ( 20,889 ) $ 21,372 $ ( 163 ) $ ( 175,326 ) 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. As of March 31, 2023 , approximately $ 22.5 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 $ 2.2 million and $ 0.5 million as of March 31, 2023 and December 31, 2022 , respectively.
Drug Product Revenue	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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Astellas Japan Agreement $ 1,732 $ 7,594 Astellas Europe Agreement 377 — Drug product revenue $ 2,109 $ 7,594 Astellas Japan Agreement 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 adjustments 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. During the three months ended March 31, 2022, the Company fulfilled a shipment obligation under the terms of Astellas Japan Amendment, and recognized related drug product revenue of $ 9.8 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 recorded a reduction to the drug product revenue of $ 2.2 million during the first quarter of 2022. 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, estimated cost to convert the API to bulk product tablets, and estimated yield from the manufacture of bulk product tablets, among others. As of March 31, 2023, t he balances related to the API price true-up under the Astellas Japan Agreement were $ 3.2 million in accrued liabilities and $ 1.6 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, 2022, the related balance in accrued liabilities was $ 6.5 million. 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, and 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. During the first quarter of 2022, 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, the Company reclassified the related deferred revenue to accrued liabilities during the year ended December 31, 2022. As of December 31, 2022, the related balance was $ 57.4 million in accrued liabilities. Further during the three months ended March 31, 2023 , the Company reclassified $ 16.6 million from the related deferred revenue to accrued liabilities. As of March 31, 2023, the balances related to the bulk drug product price true-up under the Astellas Europe Agreement and the Astellas EU Supply Agreement were $ 57.5 million in accounts payable and $ 16.4 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 $ 0.4 million as drug product revenue from the deferred revenue under the Astellas Europe Agreement during the three months ended March 31, 2023. 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 Additions Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 40,303 ) $ — $ 377 $ 16,552 $ ( 23,374 ) AstraZeneca U.S./RoW Agreement There was no shipment of bulk drug product to AstraZeneca as commercial supply under the terms of the AstraZeneca Master Supply Agreement during the three months ended March 31, 2023 and 2022. During the first quarter of 2022, the Company evaluated the current developments in the U.S. market, and updated its estimates of variable consideration associated with bulk drug product shipments to AstraZeneca in prior years as commercial supply. As a result, the Company reclassified $ 11.2 million from the related deferred revenue to accrued liabilities during the year ended December 31, 2022. As of each of March 31, 2023 and December 31, 2022, the related balance in accrued liabilities was $ 11.2 million, representing the Company’s best estimate that this amount will be paid within the next 12 months .

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2023
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 March 31, 2023 2022 Employee stock options 7,578 9,484 RSUs, PRSUs and TSR awards 2,762 2,196 ESPP 362 473 10,702 12,153

Collaboration Agreements, Lic_2

Collaboration Agreements, License Agreement and Revenues (Tables)	3 Months Ended
	Mar. 31, 2023
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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Direct Sales: Gross revenue $ 3,060 $ 2,830 Discounts and rebates ( 273 ) ( 175 ) Sales returns 2 3 Direct sales revenue, net 2,789 2,658 Sales to Falikang: Gross transaction price 34,249 22,726 Profit share ( 14,988 ) ( 8,849 ) Net transaction price 19,261 13,877 Decrease in deferred revenue 2,111 2,346 Sales to Falikang revenue, net 21,372 16,223 Total product revenue, net $ 24,161 $ 18,881
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 $ ( 175,646 ) $ ( 20,889 ) $ 21,372 $ ( 163 ) $ ( 175,326 )
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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, 2023 2022 Astellas Japan Agreement $ 1,732 $ 7,594 Astellas Europe Agreement 377 — Drug product revenue $ 2,109 $ 7,594
Summary of Amounts Recognized as Revenue	Amounts recognized as revenue under the Eluminex were as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Eluminex License revenue $ 6,000 $ — Other revenue - contract manufacturing $ 235 $ 762
Drug Product Revenue [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 Additions Recognized as Revenue Reclassified to Accrued Liability / Accounts Payable Balance at Drug product revenue - deferred revenue: Astellas Europe Agreement $ ( 40,303 ) $ — $ 377 $ 16,552 $ ( 23,374 )
Japan [Member]
Summary of License Revenue and Development Revenue Recognized under Agreement	Amounts recognized as license revenue and development revenue under the Astellas Japan Agreement were as follows for the three months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Astellas Japan Agreement License revenue $ — $ — Development revenue $ 95 $ 32
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 March 31, 2023 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 16,977 Total license and development revenue $ 117,324
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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 Astellas Europe Agreement License revenue $ — $ 22,590 Development revenue $ 1,529 $ 5,148
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 March 31, 2023 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 281,794 Total license and development revenue $ 900,769
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 months ended March 31, 2023 and 2022 (in thousands): Three Months Ended March 31, Agreement Performance Obligation 2023 2022 AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement License revenue $ — $ — Development revenue 2,032 5,819
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 through March 31, 2023 and accounts receivable has been allocated to each of the following performance obligations under the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, along with any associated deferred revenue as follows (in thousands): AstraZeneca U.S./RoW Agreement and Cumulative Revenue Deferred Revenue at Total Consideration License $ 341,844 $ — $ 341,844 Co-development, information sharing & 617,670 — 617,670 China performance obligation * 128,106 175,326 303,432 Total license and development revenue $ 1,087,620 $ 175,326 ** $ 1,262,946 * China performance obligation revenue is recognized as product revenue, as described under Product Revenue, Net section below. ** Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the consolidated balance sheets. As of March 31, 2023, deferred revenue included $ 156.2 million related to the AstraZeneca U.S./RoW Agreement and AstraZeneca China Agreement, which represents the net of $ 175.3 million of deferred revenue presented above and a $ 19.1 million unbilled co-development revenue under the AstraZeneca China Amendment.

Equity method investment - Va_2

Equity method investment - Variable Interest Entity (Tables)	3 Months Ended
	Mar. 31, 2023
Acquisition And Variable Interest Entity [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 % $ 5,061 $ 796 $ 27 $ 5,884

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2023
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): March 31, 2023 Level 1 Level 2 Level 3 Total Money market funds $ 42,740 $ — $ — $ 42,740 Corporate bonds — 41,304 — 41,304 Commercial paper — 42,970 — 42,970 U.S. government bonds 57,141 14,425 — 71,566 Agency bonds — 9,075 — 9,075 Asset-backed securities — 2,484 — 2,484 Total $ 99,881 $ 110,258 $ — $ 210,139 December 31, 2022 Level 1 Level 2 Level 3 Total Money market funds $ 19,881 $ — $ — $ 19,881 Corporate bonds — 82,008 — 82,008 Commercial paper — 57,381 — 57,381 U.S. government bonds 98,972 12,373 — 111,345 Agency bonds — 11,468 — 11,468 Asset-backed securities — 2,474 — 2,474 Foreign government bonds — 4,980 — 4,980 Convertible promissory note — — 1,000 1,000 Total $ 118,853 $ 170,684 $ 1,000 $ 290,537

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents	Cash and cash equivalents consisted of the following (in thousands): March 31, 2023 December 31, 2022 Cash $ 145,810 $ 135,819 Money market funds 42,740 19,881 Total cash and cash equivalents $ 188,550 $ 155,700
Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments	The Company’s investments consist primarily of available-for-sale debt investments. 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): March 31, 2023 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 41,760 $ 1 $ ( 457 ) $ 41,304 Commercial paper 42,970 — — 42,970 U.S. government bonds 72,130 1 ( 565 ) 71,566 Agency bonds 9,183 — ( 108 ) 9,075 Asset-backed securities 2,491 — ( 7 ) 2,484 Total investments $ 168,534 $ 2 $ ( 1,137 ) $ 167,399 December 31, 2022 Amortized Cost Gross Unrealized Gross Unrealized Estimated Corporate bonds $ 83,080 $ — $ ( 1,072 ) $ 82,008 Commercial paper 57,381 — — 57,381 U.S. government bonds 112,547 5 ( 1,207 ) 111,345 Agency bonds 11,690 — ( 222 ) 11,468 Asset-backed securities 2,484 — ( 10 ) 2,474 Foreign government bonds 5,007 — ( 27 ) 4,980 Convertible promissory note 1,000 — — 1,000 Total investments $ 273,189 $ 5 $ ( 2,538 ) $ 270,656
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, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position (in thousands): March 31, 2023 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ 2,469 $ ( 7 ) $ 36,084 $ ( 450 ) $ 38,553 $ ( 457 ) U.S. government bonds 4,955 ( 1 ) 43,794 ( 564 ) 48,749 ( 565 ) Agency bonds — — 9,075 ( 108 ) 9,075 ( 108 ) Asset-backed securities 2,483 ( 7 ) — — 2,483 ( 7 ) Total $ 9,907 $ ( 15 ) $ 88,953 $ ( 1,122 ) $ 98,860 $ ( 1,137 ) December 31, 2022 Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Estimated Gross Unrealized Estimated Gross Unrealized Corporate bonds $ 6,738 $ ( 147 ) $ 75,270 $ ( 925 ) $ 82,008 $ ( 1,072 ) U.S. government bonds 22,326 ( 13 ) 67,909 ( 1,194 ) 90,235 ( 1,207 ) Agency bonds — — 11,468 ( 222 ) 11,468 ( 222 ) Asset-backed securities 2,474 ( 10 ) — — 2,474 ( 10 ) Foreign government bonds - — 4,980 ( 27 ) 4,980 ( 27 ) Total $ 31,538 $ ( 170 ) $ 159,627 $ ( 2,368 ) $ 191,165 $ ( 2,538 )
Schedule of Inventory	Inventories consisted of the following (in thousands): March 31, 2023 December 31, 2022 Raw materials $ 1,226 $ 1,241 Work-in-progress $ 37,273 36,003 Finished goods $ 3,957 3,192 Total inventories $ 42,456 $ 40,436
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): March 31, 2023 December 31, 2022 Preclinical and clinical trial accruals $ 42,953 $ 57,780 API and bulk drug product price true-up 30,758 75,055 Payroll and related accruals 12,230 22,562 Accrued co-promotion expenses - current 36,688 36,677 Roxadustat profit share to AstraZeneca 7,311 7,280 Property taxes and other taxes 8,041 7,691 Professional services 8,354 5,480 Current portion of liability related to sale of future revenues 3,212 — Other 7,495 7,248 Total accrued and other current liabilities $ 157,042 $ 219,773

Liability Related to Sale of _2

Liability Related to Sale of Future Revenues (Tables)	3 Months Ended
	Mar. 31, 2023
Liability Related to Sale of Future Royalties [Abstract]
Schedule of Activity of Liability Related to Sale of Future Revenues	The following table summarizes the activity of the liability related to sale of future revenues for the three months ended March 31, 2023: Three Months Ended Liability related to sale of future revenues - beginning balance $ 49,333 Interest expense recognized 2,249 Liability related to sale of future revenues - ending balance 51,582 Less: Current portion classified to accrued and other current liabilities ( 3,212 ) Liability related to sale of future revenues, non-current $ 48,370

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2023 Segment
Accounting Policy [Line Items]
Number of reportable segment	1

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
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	10,702	12,153
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	7,578	9,484
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	2,762	2,196
ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	362	473

Collaboration Agreements, Lic_3

Collaboration Agreements, License Agreement and Revenues - Astellas Agreements - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended
	Apr. 30, 2006	Jun. 30, 2005	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			$ 36,161,000	$ 60,827,000
Deferred Revenue			16,495,000		$ 12,739,000
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			2,109,000	7,594,000
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 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue			$ 1,700,000	9,800,000
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
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
Transaction price, variable consideration from estimated future co-development billing			5,800,000
Percentage of joint development costs committed to fund	50%
Transaction price and allocated to performance obligations				$ 25,000,000
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
	Jul. 30, 2013	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		$ 36,161	$ 60,827
Deferred Revenue		16,495		$ 12,739
Drug product revenue recognized		36,161	60,827
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		24,161	18,881
Drug product revenue recognized		24,161	18,881
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		2,109	7,594
Drug product revenue recognized		$ 2,109	7,594
AstraZeneca Agreements [Member] | U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments	$ 1,200,000
Additional consideration based on net sales description		low 20% range
Aggregate consideration received excluding drug product revenue		$ 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
Direct Sales [Member] | Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue		2,789	2,658
Drug product revenue recognized		$ 2,789	$ 2,658

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
	Mar. 31, 2023	Mar. 31, 2022
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 36,161	$ 60,827
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	6,000	22,590
Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	3,891	11,762
Astellas Agreement [Member] | License Revenue [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
Astellas Agreement [Member] | License Revenue [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	22,590
Astellas Agreement [Member] | Development Revenue [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	95	32
Astellas Agreement [Member] | Development Revenue [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	1,529	5,148
AstraZeneca Agreements [Member] | License Revenue [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0
AstraZeneca Agreements [Member] | Development Revenue [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 2,032	$ 5,819

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	Mar. 31, 2023	Dec. 31, 2022
Astellas Agreement [Member] | Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	$ 117,324
Astellas Agreement [Member] | Japan [Member] | Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	16,977
Astellas Agreement [Member] | Japan [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	100,347
Astellas Agreement [Member] | Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	900,769
Astellas Agreement [Member] | Europe [Member] | Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	281,794
Astellas Agreement [Member] | Europe [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total Consideration	618,975
AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	175,326	$ 175,646
AstraZeneca Agreements [Member] | U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	1,087,620
Deferred Revenue	175,326
Total Consideration	1,262,946
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	341,844
Deferred Revenue	0
Total Consideration	341,844
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | Co-development, information sharing & committee services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	617,670
Deferred Revenue	0
Total Consideration	617,670
AstraZeneca Agreements [Member] | U.S./RoW and China [Member] | China performance obligation [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	128,106
Deferred Revenue	175,326
Total Consideration	$ 303,432

Collaboration Agreements, Lic_7

Collaboration Agreements, License Agreement and Revenues - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail)	3 Months Ended
	Mar. 31, 2023 USD ($)
Europe [Member] | Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	$ 5,800,000
Changes in revenue from changes to estimated variable consideration	0
U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Transaction price, variable consideration from estimated future co-development billing	9,800,000
Changes in revenue from changes to estimated variable consideration	$ 0

Collaboration Agreements, Lic_8

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations Deferred Revenue (Parenthetical) (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred revenue, net of current	$ 163,089	$ 185,722
AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	175,326	$ 175,646
AstraZeneca Agreements [Member] | U.S./RoW [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred revenue, net of current	156,200
Deferred Revenue	175,300
Net unbilled co-development revenue	$ 19,100

Collaboration Agreements, Lic_9

Collaboration Agreements, License Agreement and Revenues - Summary of Product Revenue, Net (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation Of Revenue [Line Items]
Total revenue	$ 36,161	$ 60,827
Product Revenue, Net [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	24,161	18,881
Product Revenue, Net [Member] | Direct Sales [Member]
Disaggregation Of Revenue [Line Items]
Gross revenue	3,060	2,830
Total revenue	2,789	2,658
Product Revenue, Net [Member] | Direct Sales [Member] | Discounts and Rebates [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(273)	(175)
Product Revenue, Net [Member] | Direct Sales [Member] | Sales Returns [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	2	3
Product Revenue, Net [Member] | Sales To Falikang [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	21,372	16,223
Gross transfer price	34,249	22,726
Product Revenue, Net [Member] | Sales To Falikang [Member] | Profit Share [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	(14,988)	(8,849)
Product Revenue, Net [Member] | Sales To Falikang [Member] | Net Transfer Price [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	19,261	13,877
Product Revenue, Net [Member] | Sales To Falikang [Member] | Decrease in deferred revenue
Disaggregation Of Revenue [Line Items]
Total revenue	$ 2,111	$ 2,346

Collaboration Agreements, Li_10

Collaboration Agreements, License Agreement and Revenues - Product Revenue, Net - Additional Information 1 (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	$ 36,161	$ 60,827
Constrained for Future Recognition [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	2,100	2,300
Product Revenue, Net [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total revenue	24,161	18,881
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	300
AstraZeneca Agreements [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	175,326		$ 175,646
AstraZeneca Agreements [Member] | China [Member]
Contract with Customer, Liability [Abstract]
Deferred Revenue	22,500
Beijing Falikang Pharmaceutical Co Ltd | Product Revenue, Net [Member]
Contract with Customer, Liability [Abstract]
Reductions to gross accounts receivable	$ 2,200	$ 500

Collaboration Agreements, Li_11

Collaboration Agreements, License Agreement and Revenues - Roll-forward of Related Contract Liabilities (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
AstraZeneca Agreements [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2022	$ (175,646)
Additions	(20,889)
Currency Translation and Other	163
Recognized as Revenue	21,372
Balance at March 31, 2022	(175,326)
Drug Product Revenue [Member] | Astellas Agreement [Member] | Europe [Member]
Contract with Customer Liability [Line Items]
Balance at December 31, 2022	(40,303)
Additions	0
Reclassified to Accrued Liability	16,552
Recognized as Revenue	377
Balance at March 31, 2022	$ (23,374)

Collaboration Agreements, Li_12

Collaboration Agreements, License Agreement and Revenues - Drug Product Revenue - Summary of Drug Product Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 36,161	$ 60,827
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	2,109	7,594
Drug Product Revenue [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,700	9,800
Drug Product Revenue [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	2,100
Drug Product Revenue [Member] | Astellas Agreement [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,732	7,594
Drug Product Revenue [Member] | Astellas Agreement [Member] | Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	$ 377	$ 0

Collaboration Agreements, Li_13

Collaboration Agreements, License Agreement and Revenues - Drug Product Revenue - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue	$ 16,495		$ 12,739
Drug product revenue recognized	36,161	$ 60,827
Other long-term liabilities	7,063		6,440
Astra Zeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty revenue recognized as drug product revenue	21,372
Drug Product Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	2,109	7,594
Drug Product Revenue [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	2,100
Drug Product Revenue [Member] | Europe [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	377	0
Drug Product Revenue [Member] | Europe [Member] | Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	16,600
Accrued liabilities			57,400
Drug Product Revenue [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	400
Drug Product Revenue [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,700	9,800
Drug Product Revenue [Member] | Japan [Member] | Astellas Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	1,732	7,594
Accrued liabilities	3,200		6,500
Other long-term liabilities	1,600
Drug Product Revenue [Member] | API Shipment [Member] | Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized		$ 2,200
Bulk Drug Product [Member] | Astra Zeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Drug product revenue recognized	11,200
Accrued liabilities	11,200		$ 11,200
Bulk Drug Product [Member] | Europe [Member] | Astellas Europe Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accrued liabilities	16,400
Accounts payable	$ 57,500

Collaboration Agreements, Li_14

Collaboration Agreements, License Agreement and Revenues - Eluminex Agreement - Additional Information 2 (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jul. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue		$ 36,161	$ 60,827
Eluminex [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Aggregate consideration received for milestone and upfront payments	$ 8,000
Future manufacturing clinical regulatory and commercial milestone payments	64,000
Commercial milestone	$ 36,000
Eluminex [Member] | Cornea Products [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Percentage of product manufacturing costs until manufacturing technology fully transferred			10%
China [Member] | Eluminex [Member] | Biosynthetic Cornea [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Milestone Payments		3,000
Manufacturing related milestone payments		$ 3,000

Collaboration Agreements, Li_15

Collaboration Agreements, License Agreement and Revenues - Summary of Amounts Recognized as Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 36,161	$ 60,827
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	6,000	22,590
License Revenue [Member] | Eluminex [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	6,000
Other Revenue - Contract Manufacturing [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	3,891	11,762
Other Revenue - Contract Manufacturing [Member] | Eluminex [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 235	$ 762

Equity method investment - Va_3

Equity method investment - Variable Interest Entity - Additional Information (Detail)	Mar. 31, 2023
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%

Equity method investment - Va_4

Equity method investment - Variable Interest Entity - Summary of Equity Method Investment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Acquisition And Variable Interest Entity [Line Items]
Beginning balance	$ 5,061
Share of Net Income	796	$ 320
Ending balance	$ 5,884
Beijing Falikang Pharmaceutical Co. Ltd [Member]
Acquisition And Variable Interest Entity [Line Items]
Ownership Percentage	51.10%
Beginning balance	$ 5,061
Share of Net Income	796
Currency Translation	27
Ending balance	$ 5,884

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 167,399	$ 270,656
Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	41,304	82,008
Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	42,970	57,381
Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,484	2,474
Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		4,980
Convertible promissory note [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		1,000
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	210,139	290,537
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	42,740	19,881
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	41,304	82,008
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	42,970	57,381
Fair Value, Measurements, Recurring [Member] | U.S. government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	71,566	111,345
Fair Value, Measurements, Recurring [Member] | Agency bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	9,075	11,468
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,484	2,474
Fair Value, Measurements, Recurring [Member] | Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		4,980
Fair Value, Measurements, Recurring [Member] | Convertible promissory note [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		1,000
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	99,881	118,853
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	42,740	19,881
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	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	57,141	98,972
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 1 [Member] | Asset-backed securities [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] | Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		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	110,258	170,684
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	41,304	82,008
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	42,970	57,381
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	14,425	12,373
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	9,075	11,468
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	2,484	2,474
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		4,980
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Convertible promissory note [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		1,000
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	1,000
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	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, Recurring [Member] | Level 3 [Member] | Asset-backed securities [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] | Foreign government bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ in Millions	Mar. 31, 2023 USD ($)
Fair Value Disclosures [Abstract]
Fair value of US treasury notes and bills transfered from level 1 to level 2	$ 7

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash	$ 145,810	$ 135,819
Money market funds	42,740	19,881
Total cash and cash equivalents	$ 188,550	$ 155,700

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 188,550,000		$ 155,700,000
Other-than-temporary impairment loss	0	$ 0
API and bulk drug product price true-up	30,758,000		75,055,000
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 98,900,000		$ 92,500,000

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) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 168,534	$ 273,189
Gross Unrealized Holding Gains	2	5
Gross Unrealized Holding Losses	(1,137)	(2,538)
Estimated Fair Value	167,399	270,656
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	41,760	83,080
Gross Unrealized Holding Gains	1	0
Gross Unrealized Holding Losses	(457)	(1,072)
Estimated Fair Value	41,304	82,008
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42,970	57,381
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	42,970	57,381
U.S. government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	72,130	112,547
Gross Unrealized Holding Gains	1	5
Gross Unrealized Holding Losses	(565)	(1,207)
Estimated Fair Value	71,566	111,345
Agency bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,183	11,690
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(108)	(222)
Estimated Fair Value	9,075	11,468
Foreign government bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		5,007
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		(27)
Estimated Fair Value		4,980
Convertible promissory note [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,000
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		0
Estimated Fair Value		1,000
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,491	2,484
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	(7)	(10)
Estimated Fair Value	$ 2,484	$ 2,474

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) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
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	$ 9,907	$ 31,538
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(15)	(170)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	88,953	159,627
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(1,122)	(2,368)
Available for sale securities in continual unrealized loss position, estimated fair value	98,860	191,165
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(1,137)	(2,538)
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	2,469	6,738
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(7)	(147)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	36,084	75,270
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(450)	(925)
Available for sale securities in continual unrealized loss position, estimated fair value	38,553	82,008
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(457)	(1,072)
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	4,955	22,326
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(1)	(13)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	43,794	67,909
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(564)	(1,194)
Available for sale securities in continual unrealized loss position, estimated fair value	48,749	90,235
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(565)	(1,207)
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	0	0
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	0	0
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	9,075	11,468
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	(108)	(222)
Available for sale securities in continual unrealized loss position, estimated fair value	9,075	11,468
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	(108)	(222)
Asset-backed securities [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	2,483	2,474
Available for sale securities in continual unrealized loss position, less than 12 months, gross unrealized holding losses	(7)	(10)
Available for sale securities in continual unrealized loss position, 12 months or more, estimated fair value	0	0
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses	0	0
Available for sale securities in continual unrealized loss position, estimated fair value	2,483	2,474
Available for sale securities in continual unrealized loss position, gross unrealized holding losses	$ (7)	(10)
Foreign 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		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		4,980
Available for sale securities in continual unrealized loss position, 12 months or more, gross unrealized holding losses		(27)
Available for sale securities in continual unrealized loss position, estimated fair value		4,980
Available for sale securities in continual unrealized loss position, gross unrealized holding losses		$ (27)

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule of Investments [Abstract]
Raw materials	$ 1,226	$ 1,241
Work-in-progress	37,273	36,003
Finished goods	3,957	3,192
Total inventories	$ 42,456	$ 40,436

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accrued Liabilities, Current [Abstract]
Preclinical and clinical trial accruals	$ 42,953	$ 57,780
API and bulk drug product price true-up	30,758	75,055
Payroll and related accruals	12,230	22,562
Accrued co-promotion expenses - current	36,688	36,677
Roxadustat profit share to AstraZeneca	7,311	7,280
Property taxes and other taxes	8,041	7,691
Professional services	8,354	5,480
Current portion of liability related to sale of future revenues	3,212	0
Other	7,495	7,248
Total accrued and other current liabilities	$ 157,042	$ 219,773

Liability Related to Sale of _3

Liability Related to Sale of Future Revenues - Additional Information (Details) - USD ($)		3 Months Ended
	Nov. 04, 2022	Mar. 31, 2023	Mar. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		$ 36,161,000	$ 60,827,000
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		19.64%
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		$ 24,161,000	18,881,000
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		6,000,000	22,590,000
Other Revenue - Contract Manufacturing [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		3,891,000	11,762,000
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
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		1,600,000
Drug Product Revenue [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		2,109,000	$ 7,594,000
Drug Product Revenue [Member] | Astellas Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenue		2,100,000
Non-cash interest expense related to drug product revenue		$ 2,200,000

Liability Related to Sale of _4

Liability Related to Sale of Future Revenues - Schedule of Activity of Liability Related to Sale of Future Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Liability Related to Sale of Future Royalties [Abstract]
Liability related to sale of future revenues - beginning balance	$ 49,333
Interest expense recognized	2,249	$ 0
Liability related to sale of future revenues - ending balance	51,582
Less: Current portion classified to accrued and other current liabilities	(3,212)
Liability related to sale of future revenues, non-current	$ 48,370

At-the-Market Program - Additio

At-the-Market Program - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Feb. 27, 2023	Mar. 31, 2023	Mar. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of common stock under ATM Program		$ 31,131
Proceeds from sale of common stock		$ 907	$ 183
ATM Program [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of common stock under ATM Program	$ 200,000
Issuance of common stock under ATM Program shares		1,541,579
Proceeds from sale of common stock		$ 31,100
Net of commissions to sales agents		$ 30,800
Weighted-average offering prices per share		$ 20.25

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Related Party Transaction [Line Items]
Accounts receivable from related parties	$ 11,563		$ 12,088
Accrued liabilities to related party	19,594		63,886
Investment income (loss)	796	$ 320
Equity method investments	5,884		5,061
Astellas [Member]
Related Party Transaction [Line Items]
Drug product revenue from a related party	2,100	7,600
Due to related parties	78,700		63,900
Astellas [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties	1,600		1,500
Deferred Revenue	23,400		40,300
Astellas [Member] | License and Development [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	1,600	27,800
Falikang [Member]
Related Party Transaction [Line Items]
Accounts receivable from related parties	9,900		10,500
Investment income (loss)	800	300
Equity method investments	$ 5,900		$ 5,100
Percentage of outstanding shares owned	51.10%
Falikang [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	$ 21,400	$ 16,200

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	2 Months Ended	3 Months Ended
	May 31, 2021 PutativeClassAction	Mar. 31, 2023 USD ($)
Commitments And Contingencies [Line Items]
Operating lease liability		$ 86.8
Outstanding non-cancelable purchase obligations		51.9
Putative securities class action complaints filed | PutativeClassAction	5
Manufacture and Supply of Roxadustat [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		4.1
Manufacture and Supply of Pamrevlumab [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		22.4
Other Purchases [Member]
Commitments And Contingencies [Line Items]
Outstanding non-cancelable purchase obligations		25.4
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) - USD ($) $ in Millions			3 Months Ended
	May 05, 2023	Apr. 29, 2023	Mar. 31, 2023
Debt Financing Agreement [Member]
Subsequent Event [Line Items]
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.During the term of the Term Loans, the Company is required to maintain a minimum balance of $30.0 million of unrestricted cash and cash equivalents held in accounts in the United States, tested monthly on each interest payment date (after netting the monthly interest payment then due).
Subsequent Event [Member] | Debt Financing Agreement [Member]
Subsequent Event [Line Items]
Interest rate per annum		14%
Fortis Therapeutics [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Product development obligations	$ 5
Payment to options exercised	80
Contingent payment associated with business acquisition	$ 200
Initial Term Loan [Member] | Subsequent Event [Member] | Debt Financing Agreement [Member]
Subsequent Event [Line Items]
Term loan		$ 75
Delayed Draw Term Loan [Member] | Subsequent Event [Member] | Debt Financing Agreement [Member]
Subsequent Event [Line Items]
Term loan		$ 37.5
Maximum term loan funding period from signing date		24 days
Delayed Draw Term Loan 2 | Subsequent Event [Member] | Debt Financing Agreement [Member]
Subsequent Event [Line Items]
Term loan		$ 37.5
Minimum [Member] | Subsequent Event [Member] | Debt Financing Agreement [Member]
Subsequent Event [Line Items]
Unrestricted cash and cash equivalent balance required to maintain in accounts		$ 30