Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

8. Balance Sheet Components

Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):


	December 31,
	2023		2022
Cash	$	63,396	$	135,819
Commercial paper		36,016		—
Money market funds		12,288		19,881
U.S. government bonds		1,988		—
Total cash and cash equivalents	$	113,688	$	155,700

At December 31, 2023 and 2022, a total of $32.2 million and $92.5 million, respectively, 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.

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):


	December 31, 2023
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	13,988	$	9	$	(5	)	$	13,992
Commercial paper		52,273		—		—			52,273
U.S. government bonds		45,783		20		—			45,803
Agency bonds		9,830		1		(1	)		9,830
Total investments	$	121,874	$	30	$	(6	)	$	121,898

	December 31, 2022
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
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):


	December 31, 2023
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
Corporate bonds	$	—	$	—		$	3,495	$	(5	)	$	3,495	$	(5	)
U.S. government bonds		4,984		—			—		—			4,984		—
Agency bonds		4,987		(1	)		—		—			4,987		(1	)
Total	$	9,971	$	(1	)	$	3,495	$	(5	)	$	13,466	$	(6	)

	December 31, 2022
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
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	)

The contractual maturities of all available-for-sale investments were with in one year as of December 31, 2023.

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. During the three years ended December 31, 2023, the Company did not recognize any other-than-temporary impairment loss.

Inventories

Inventories consisted of the following (in thousands):


	December 31,
	2023		2022
Raw materials	$	1,376	$	1,241
Work-in-progress		34,614		36,003
Finished goods		5,575		3,192
Total inventories	$	41,565	$	40,436

The provision to write-down excess and obsolete inventory were immaterial as of December 31, 2023 and December 31, 2022.

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	December 31,
	2023			2022
Contract assets	$	26,481		$	17,488
Deferred revenues from associated contracts		(26,481	)		(17,488	)
Net contract assets		—			—
Insurance proceeds receivable for litigation settlement		28,500
Prepaid assets		6,644			9,730
Other current assets		6,711			4,353
Total prepaid expenses and other current assets	$	41,855		$	14,083

The unbilled contract assets as of December 31, 2023 and 2022 included $22.5 million and $17.5 million, respectively, related to unbilled co-development revenue under the AstraZeneca China Amendment. In addition, the unbilled contract assets as of December 31, 2023 included the $4.0 million unbilled regulatory milestone payment under the AstraZeneca China Agreement. See the AstraZeneca China Agreement section in Note 3, Collaboration Agreements, License Agreement and Revenues, for details.

As of December 31, 2023, the Company recorded a $28.5 million receivable in prepaid expenses and other current assets, corresponding to the accrued litigation settlement of the same amount related to the Company’s agreement in principle with plaintiffs to settle the class action lawsuit. As the Company maintains insurance that covers exposure related to the class action lawsuit, this amount is fully recoverable under the Company’s insurance policies. The determination that the recorded receivables are probable of collection is based on the terms of the applicable insurance policies and communications with the insurers. See the Accrued and Other Current Liabilities section below, and the Legal Proceedings and Other Matters section in Note 12, Commitments and Contingencies, for details.

Property and Equipment

Property and equipment consisted of the following (in thousands):


	December 31,
	2023			2022
Leasehold improvements	$	102,109		$	102,580
Laboratory equipment		22,757			21,175
Machinery		9,454			9,642
Computer equipment		9,490			9,486
Furniture and fixtures		6,184			6,200
Construction in progress		62			204
Total property and equipment	$	150,056		$	149,287
Less: accumulated depreciation		(136,930	)		(128,682	)
Property and equipment, net	$	13,126		$	20,605

Depreciation expense for the years ended December 31, 2023, 2022 and 2021 was $9.5 million, $10.0 million and $10.2 million, respectively.

Accrued and Other Current Liabilities

Accrued and other current liabilities consisted of the following (in thousands):


	December 31,
	2023		2022
Preclinical and clinical trial accruals	$	27,663	$	57,780
API and bulk drug product price true-up		50,978		75,055
Litigation settlement		28,500		—
Payroll and related accruals		20,267		22,562
Accrued co-promotion expenses - current		10,309		36,677
Roxadustat profit share to AstraZeneca		7,084		7,280
Property taxes and other taxes		6,615		7,691
Professional services		7,103		5,480
Current portion of liability related to sale of future revenues		5,654		—
Accrued restructuring charge		3,697		—
Other		5,021		7,248
Total accrued and other current liabilities	$	172,891	$	219,773

The accrued liabilities of $51.0 million for API and bulk drug product price true-up as of December 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, Net section in Note 3, Collaboration Agreements, License Agreement and Revenues, for details.

As of December 31, 2023, the accrued litigation settlement of $28.5 million was related to the Company’s agreement in principle with plaintiffs to settle the class action lawsuit. See the Prepaid Expenses and Other Current Assets section above, and the Legal Proceedings and Other Matters section in Note 12, Commitments and Contingencies, for details.

On July 14, 2023, the Company approved a restructuring plan (the “Plan”) to lower the Company’s operating expenses. The Plan included a reduction to the Company’s U.S. workforce of approximately 32%. As a result, the Company recorded a total of $12.6 million non-recurring restructuring charge during the third quarter of 2023, primarily consisting of notice period and severance payments, accrued vacation, and employee benefits contributions. During the year ended December 31, 2023, total cash payments under the Plan was $8.9 million. The remaining accrued restructuring charge was $3.7 million as of December 31, 2023 and will be substantially paid out by early 2024. The Plan is in connection with the Company’s efforts to streamline operations to align with the Company’s business goals.