0001628280-23-030698 | 10-Q | XBRL Viewer

INVENTORIES (Tables)

6 Months Ended

Jun. 30, 2023

Inventories related to our commercial product, Auryxia, consists of the following (in thousands):


	June 30, 2023		December 31, 2022
Work-in-process	$	8,571	$	7,892
Finished goods	12,334		13,676
Inventories, current	$	20,905	$	21,568
Raw materials included in other long-term assets	229		610
Total inventories	$	21,134	$	22,178

INVENTORIES

6 Months Ended

Jun. 30, 2023

Inventory Disclosure [Abstract]

INVENTORIES

Inventories related to our commercial product, Auryxia, consists of the following (in thousands):


	June 30, 2023		December 31, 2022
Work-in-process	$	8,571	$	7,892
Finished goods	12,334		13,676
Inventories, current	$	20,905	$	21,568
Raw materials included in other long-term assets	229		610
Total inventories	$	21,134	$	22,178

Inventory written down as a result of excess, obsolescence, scrap or other reasons charged to cost of goods in the unaudited condensed consolidated statement of operations and comprehensive income (loss) totaled approximately $0.3 million and $2.1 million during the three months ended June 30, 2023 and 2022, respectively, and $0.6 million and $7.4 million during the six months ended June 30, 2023 and 2022, respectively.

In accordance with GAAP, to date, the Company recorded prepaid amounts related to vadadustat drug substance as prepaid manufacturing costs. As of June 30, 2023 and December 31, 2022, the Company has $15.6 million included in other current assets on the condensed consolidated balance sheet. Released batches are expensed as research and development expense. During the quarter ended June 30, 2023, vadadustat received marketing authorization in the European Commission (EC) under the trade name Vafseo. Future costs associated with converting the drug substance to finished goods will be capitalized as inventory on the condensed consolidated balance sheet of the Company.

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Assumptions Used in Black-Scholes Option Pricing Model (Details) - Stock Incentive Plan, 2014 And 2023 - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, minimum	3.67%	2.80%	3.54%	1.69%
Risk-free interest rate, maximum	3.99%	3.01%	3.99%	3.01%
Expected volatility, minimum	102.31%	87.99%	100.97%	79.77%
Expected volatility, maximum	111.71%	91.57%	111.71%	91.57%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Fair value at grant date (in dollars per share)	$ 0.97	$ 0.31	$ 0.56	$ 1.21
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (years)	5 years 6 months 3 days	5 years 6 months 3 days	5 years 6 months 3 days	5 years 6 months 3 days
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected term (years)	6 years 3 months	6 years 3 months	6 years 3 months	6 years 3 months

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Equity Plans (Details)	Jun. 30, 2023 shares
Keryx Equity Plans(1)(2)*
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awards outstanding (in shares)	287,100
Additional awards authorized for grant (in shares)	0
Akebia Therapeutics, Inc. Amended and Restated 2008 Equity Incentive Plan (the 2008 Plan)(2)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awards outstanding (in shares)	419
Additional awards authorized for grant (in shares)	0
Akebia Therapeutics, Inc. 2014 Incentive Plan, as amended (2) (the 2014 Plan) (replaces 2008 Plan)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awards outstanding (in shares)	17,513,530
Additional awards authorized for grant (in shares)	0
Akebia Therapeutics, Inc. 2023 Stock Incentive Plan (the 2023 Plan) (replaces 2014 Plan)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awards outstanding (in shares)	549,000
Additional awards authorized for grant (in shares)	16,256,679

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

NATURE OF BUSINESS	6 Months Ended
NATURE OF BUSINESS	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF BUSINESS	NATURE OF BUSINESS Akebia Therapeutics, Inc., referred to as Akebia or the Company, was incorporated in the State of Delaware in 2007. Akebia is a fully integrated biopharmaceutical company with the purpose of bettering the lives of people impacted by kidney disease. The Company has one commercial product, Auryxia® (ferric citrate), which is approved by the U.S. Food and Drug Administration (FDA), and marketed for two indications in the United States: the control of serum phosphorus levels in adult patients with chronic kidney disease (CKD) on dialysis (DD-CKD), and the treatment of iron deficiency anemia (IDA) in adult patients with CKD not on dialysis (NDD-CKD). Ferric citrate is also approved and marketed in Japan as an oral treatment for IDA in adult patients for the improvement of hyperphosphatemia in such patients with DD-CKD and NDD-CKD under the trade name Riona (ferric citrate hydrate). Vadadustat, the Company’s lead investigational product candidate, is an investigational oral hypoxia-inducible factor prolyl hydroxylase (HIF-PH), inhibitor designed to mimic the physiologic effect of altitude on oxygen availability. On March 29, 2022, the Company received a complete response letter (CRL) from the FDA. The CRL provided that the FDA had completed its review of the Company's new drug application (NDA) for vadadustat for the treatment of anemia due to CKD in adult patients and had determined that it could not approve the NDA in its present form. In October 2022, the Company submitted a Formal Dispute Resolution Request with the FDA and focused on the favorable balance between the benefits and risks of vadadustat for the treatment of anemia due to CKD in adult DD-CKD patients in light of safety concerns expressed by the FDA in the CRL for dialysis patients related to the rate of adjudicated thromboembolic events driven by vascular access thrombosis for vadadustat compared to the active comparator and the risk of drug-induced liver injury. In May 2023, the Office of New Drugs (OND) denied the Company's appeal but provided a path forward for the Company to resubmit the NDA for vadadustat for the treatment of anemia due to CKD for dialysis dependent patients without the need for the Company to generate additional clinical data. In July 2023, the Company held an End of Dispute Type A meeting with the FDA to align on the contents of the NDA resubmission. The Company expects to resubmit the NDA by the end of the third quarter of 2023, with a potential Prescription Drug User Fee Act (PDUFA) date that the Company projects will be in March 2024. In October 2021, the Company's former collaboration partner, Otsuka Pharmaceutical Co. Ltd. (Otsuka), submitted a Marketing Authorization Application (MAA) for vadadustat for the treatment of anemia due to CKD in adult patients with DD-CKD and NDD-CKD to the European Medicines Agency (EMA). In connection with the Termination and Settlement Agreement with Otsuka dated June 30, 2022 (Termination Agreement), Otsuka transferred the MAA for vadadustat with each of the EMA, the United Kingdom, Switzerland and Australia to the Company. In April 2023, the European Commission (EC) approved the marketing authorization of vadadustat under the trade name Vafseo for the treatment of symptomatic anemia associated with CKD in adults on chronic maintenance dialysis. In May 2023, the United Kingdom (UK) Medicines and Healthcare products Regulatory Agency approved the marketing authorization of vadadustat under the trade name Vafseo for the treatment of symptomatic anemia associated with CKD in adults on chronic maintenance dialysis. In June 2023, the Swiss Agency for Therapeutics Products approved the marketing authorization for vadadustat under the trade name Vafseo for the treatment of symptomatic anemia associated with CKD in adults on chronic maintenance dialysis. Vadadustat is approved in Japan as a treatment for anemia due to CKD in both DD-CKD and NDD-CKD patients under the trade name Vafseo, and marketed and sold in Japan by Mitsubishi Tanabe Pharma Corporation (MTPC). Vadadustat is also approved in Korea as a treatment for anemia due to CKD in DD-CKD patients. In addition, the Company continues to explore additional development opportunities to expand its pipeline and portfolio of novel therapeutics. Since inception, the Company has devoted most of its resources to research and development, including its preclinical and clinical development activities, commercializing Auryxia, and providing general and administrative support for these operations. The Company began recording revenue from the U.S. sales of Auryxia and revenue from sublicensing rights to Auryxia in Japan from the Company’s Japanese partners, Japan Tobacco, Inc. and its subsidiary Torii Pharmaceutical Co., Ltd. (collectively, JT and Torii), in December 2018. Additionally, following regulatory approval of vadadustat in Japan, the Company began recognizing royalty revenues from MTPC from the sale of Vafseo in August 2020. In February 2021, the Company entered into a royalty interest acquisition agreement with HealthCare Royalty Partners IV, L.P. (HCR) (Royalty Agreement), whereby the Company sold its right to receive royalties and sales milestones under its Collaboration Agreement with MTPC (MTPC Agreement), subject to certain caps and other terms and conditions (see Note 6 for additional information). The Company has not generated a profit to date, and may never generate profits, from product sales. Vadadustat and the Company’s other potential product candidates are subject to long development cycles, and the Company may be unsuccessful in its efforts to develop, obtain marketing approval for or market vadadustat and its other potential product candidates. If the Company does not successfully commercialize Auryxia, vadadustat, if approved, or any other potential product candidate, it may be unable to achieve profitability. The Company’s management completed its going concern assessment in accordance with Accounting Standards Codification, or ASC, 205-40, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern, or ASC 205-40. As of June 30, 2023, the Company had cash and cash equivalents of approximately $53.6 million. Based on its current operating plan, the Company believes that its cash resources will be sufficient to allow the Company to fund its current operating plan through at least the next twelve months from the filing of this Quarterly Report on Form 10-Q. If the Company’s operating performance deteriorates significantly from the levels expected in the Company’s operating plan, it would have an effect on the Company’s liquidity and its ability to continue as a going concern in the future. The Company expects to finance future cash needs through product revenue, potential strategic transactions, public or private equity or debt transactions, operating expense management, or a combination of these approaches. Assuming the Company is successful in executing its operating plan, the Company will require additional funding to fund its strategic growth beyond Auryxia or to pursue later stage development and commercial activities for its product candidates and any additional product or product candidates, including those that may be in-licensed or acquired. There can be no assurance that the current operating plan will be achieved in the time frame anticipated by the Company, or that its cash resources will fund its operating plan for the period anticipated by the Company, or that additional funding will be available on terms acceptable to the Company, or at all.

LICENSE, COLLABORATION AND OTHER REVENUE - U.S. Collaboration and License Agreement with Otsuka Pharmaceutical Co. Ltd. (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 56,376	$ 126,365	$ 96,381	$ 187,988
License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	14,132	83,056	19,431	103,307
Otsuka Pharmaceutical Company. Ltd. \| Otsuka U.S. Agreement \| License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	2,225	$ 81,135	$ 2,225	$ 86,773
Otsuka Pharmaceutical Company. Ltd. \| Packaging Validation Transfer Agreement \| License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 2,200

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS - Revisions for Product Return Reserve Errors and Other Immaterial Corrections (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 12, 2018
Condensed Consolidated Balance Sheet
Inventories	$ 20,905	$ 20,410	$ 40,226	$ 41,098	$ 20,905	$ 40,226	$ 21,568
Accounts receivable, net	19,572	18,731	82,002	65,358	19,572	82,002	40,284
Prepaid expenses and other current assets	24,398	24,703			24,398		32,864
Total current assets	118,447	120,798	308,250	305,139	118,447	308,250	185,182
Goodwill	59,044	59,044	59,044	59,044	59,044	59,044	59,044
Total assets	253,712	280,928	529,882	541,799	253,712	529,882	356,054
Accrued expenses and other current liabilities	56,408	51,079	95,005	114,243	56,408	95,005	75,777
Total current liabilities	92,184	87,656	237,401	258,497	92,184	237,401	129,536
Other non-current liabilities	17,142	16,772	74,610	83,141	17,142	74,610	15,717
Total liabilities	280,519	300,051	470,946	519,221	280,519	470,946	350,824
Accumulated deficit	(1,595,075)	(1,583,903)	(1,496,859)	(1,526,308)	(1,595,075)	(1,496,859)	(1,557,025)
Total liabilities and stockholders' equity	253,712	280,928	529,882	541,799	253,712	529,882	356,054
Condensed Consolidated Statement of Operations and Comprehensive Income
Total revenues	56,376		126,365		96,381	187,988
Cost of goods sold, product	8,273	11,178	9,589	23,105	19,452	32,694
Selling, general and administrative	27,036	25,053	32,240	44,566	52,090	76,806
Operating income (loss)	(8,996)	(25,599)	34,075	(59,581)	(34,594)	(25,504)
Net loss, basic	(11,172)	(26,878)	29,449	(63,509)	(38,050)	(34,058)
Net loss, diluted	(11,172)	(26,878)	29,449	(63,509)	(38,050)	(34,058)
Comprehensive loss	$ (11,172)	$ (26,878)	$ 29,449	$ (63,509)	$ (38,050)	$ (34,058)
Net loss per share - basic (in dollars per share)	$ (0.06)	$ (0.15)	$ 0.16	$ (0.35)	$ (0.20)	$ (0.19)
Net loss per share - diluted (in dollars per share)	$ (0.06)	$ (0.15)	$ 0.15	$ (0.35)	$ (0.20)	$ (0.19)
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Accumulated deficit	$ (26,807)	$ (19,125)	$ 58,937	$ 22,580	$ (26,807)	$ 58,937	5,230	$ 74,008
Net loss	(11,172)	(26,878)	29,449	(63,509)	(38,050)	(34,058)		(282,024)
Condensed Consolidated Statement of Cash Flows
Net loss	(11,172)	(26,878)	29,449	(63,509)	(38,050)	(34,058)		(282,024)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments				0	0	4,854
Changes in operating assets and liabilities:
Accounts receivable		21,553		(13,778)	20,712	(30,421)
Inventory				(8,490)	10,828	(4,362)
Other long-term assets				3,966	(5,876)	10,012
Accrued expense and other current liabilities		(25,115)		7,386	(19,382)	(19,464)
Other long-term liabilities		573			481	(8,622)
Net cash used in operating activities		(17,540)		(21,620)	(13,909)	(52,280)
Accumulated Deficit
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Accumulated deficit	(1,595,075)	(1,583,903)	(1,496,859)	(1,526,308)	(1,595,075)	(1,496,859)	(1,557,025)	(1,462,799)
Net loss	(11,172)	(26,878)	29,449	(63,509)
Condensed Consolidated Statement of Cash Flows
Net loss	(11,172)	(26,878)	29,449	(63,509)
Product revenue, net
Condensed Consolidated Statement of Operations and Comprehensive Income
Total revenues	$ 42,244	34,706	43,309	41,372	$ 76,950	84,681
As Previously Reported
Condensed Consolidated Balance Sheet
Inventories		20,604	36,272	39,422		36,272
Accounts receivable, net		17,781	81,869	64,582		81,869
Prepaid expenses and other current assets		25,381
Total current assets		120,719	304,163	302,687		304,163
Goodwill		55,053	55,053	55,053		55,053
Total assets		276,858	521,804	535,356		521,804
Accrued expenses and other current liabilities		46,367	91,284	109,660		91,284
Total current liabilities		82,944	233,680	253,914		233,680
Other non-current liabilities		12,643	66,889	77,743		66,889
Total liabilities		291,210	459,504	509,240		459,504
Accumulated deficit		(1,579,130)	(1,493,496)	(1,522,772)		(1,493,496)
Total liabilities and stockholders' equity		276,858	521,804	535,356		521,804
Condensed Consolidated Statement of Operations and Comprehensive Income
Cost of goods sold, product		10,473		22,333		31,923
Selling, general and administrative		25,221	32,807	44,327		77,134
Operating income (loss)		(24,938)	33,902	(58,493)		(24,591)
Net loss, basic		(26,217)	29,276	(62,421)		(33,145)
Net loss, diluted		(26,217)	29,276	(62,421)		(33,145)
Comprehensive loss		$ (26,217)	$ 29,276	$ (62,421)		$ (33,145)
Net loss per share - basic (in dollars per share)		$ (0.14)	$ 0.16	$ (0.35)		$ (0.18)
Net loss per share - diluted (in dollars per share)		$ (0.14)	$ 0.15	$ (0.35)		$ (0.18)
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Net loss		$ (26,217)	$ 29,276	$ (62,421)		$ (33,145)		(282,840)
Condensed Consolidated Statement of Cash Flows
Net loss		(26,217)	29,276	(62,421)		(33,145)		(282,840)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments				(773)		(773)
Changes in operating assets and liabilities:
Accounts receivable		21,399		(13,707)		(30,994)
Inventory				(5,247)		1,159
Other long-term assets				3,297		9,347
Accrued expense and other current liabilities		(25,047)		4,426		(18,625)
Other long-term liabilities		0				(9,030)
Net cash used in operating activities		(17,538)		(21,620)		(52,280)
As Previously Reported \| Accumulated Deficit
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Accumulated deficit		(1,579,130)	(1,493,496)	(1,522,772)		(1,493,496)		(1,460,351)
As Previously Reported \| Product revenue, net
Condensed Consolidated Statement of Operations and Comprehensive Income
Total revenues		34,828	43,703	41,448		85,151
Adjustment
Condensed Consolidated Balance Sheet
Inventories		(194)	3,954	1,676		3,954
Accounts receivable, net		950	133	776		133	1,100	700	$ 700
Prepaid expenses and other current assets		(678)
Total current assets		79	4,087	2,452		4,087
Goodwill		3,991	3,991	3,991		3,991				$ 2,600
Total assets		4,070	8,078	6,443		8,078
Accrued expenses and other current liabilities		4,712	3,721	4,583		3,721
Total current liabilities		4,712	3,721	4,583		3,721
Other non-current liabilities		4,129	7,721	5,398		7,721
Total liabilities		8,841	11,442	9,981		11,442
Accumulated deficit		(4,773)	(3,363)	(3,536)		(3,363)
Total liabilities and stockholders' equity		4,070	8,078	6,443		8,078
Condensed Consolidated Statement of Operations and Comprehensive Income
Total revenues							$ 100	1,900	$ 600
Cost of goods sold, product		705		772		771
Selling, general and administrative		(168)	(567)	239		(328)
Operating income (loss)		(661)	173	(1,088)		(913)
Net loss, basic		(661)	173	(1,088)		(913)
Net loss, diluted		(661)	173	(1,088)		(913)
Comprehensive loss		$ (661)	$ 173	$ (1,088)		$ (913)
Net loss per share - basic (in dollars per share)		$ (0.01)	$ 0	$ 0		$ (0.01)
Net loss per share - diluted (in dollars per share)		$ (0.01)	$ 0	$ 0		$ (0.01)
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Net loss		$ (661)	$ 173	$ (1,088)		$ (913)		816
Condensed Consolidated Statement of Cash Flows
Net loss		(661)	173	(1,088)		(913)		816
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments				773		5,627
Changes in operating assets and liabilities:
Accounts receivable		154		(71)		573
Inventory				(3,243)		(5,521)
Other long-term assets				669		665
Accrued expense and other current liabilities		(68)		2,960		(839)
Other long-term liabilities		573				408
Net cash used in operating activities		(2)		0		0
Adjustment \| Accumulated Deficit
Condensed Consolidated Statement of Stockholders' (Deficit) Equity
Accumulated deficit		(4,773)	(3,363)	(3,536)		(3,363)		$ (2,448)
Adjustment \| Product revenue, net
Condensed Consolidated Statement of Operations and Comprehensive Income
Total revenues		$ (122)	$ (394)	$ (76)		$ (470)

DEBT (Details) $ in Thousands						3 Months Ended			6 Months Ended
DEBT (Details) $ in Thousands	Jun. 29, 2023	Jul. 15, 2022 USD ($)	Dec. 10, 2020 USD ($)	Nov. 25, 2019 USD ($)	Nov. 11, 2019 USD ($) tranche	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Line of Credit Facility [Line Items]
Embedded debt derivative						$ 760			$ 760		$ 760
Collateral Agent, Pharmakon
Line of Credit Facility [Line Items]
Embedded debt derivative						800			800		$ 800
Term Loan \| Collateral Agent, Pharmakon \| Tranche A and B
Line of Credit Facility [Line Items]
Payment for debt prepayment premium, including accrued and unpaid interest		$ 500
Debt extinguishment loss							$ 900
Term Loan \| Collateral Agent, Pharmakon \| Tranche A
Line of Credit Facility [Line Items]
Payment for debt prepayment		5,000
Term Loan \| Collateral Agent, Pharmakon \| Tranche B
Line of Credit Facility [Line Items]
Payment for debt prepayment		$ 20,000
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity					$ 100,000
Term loan, principal payment						8,000			24,000
Term loan, maturity term, potential reduction (up to)					1 year
Term loan, amortization period, potential reduction (up to)					1 year
Prepayment premium percentage on principal if prepaid prior to fourth anniversary and after third anniversary of funding					1.00%
Prepayment premium percentage on principal if prepaid after fourth anniversary of funding					0.50%
Minimum net sales threshold, trailing period					12 months
Minimum net sales threshold					$ 85,000
Interest expense						1,600		$ 2,700	3,300	$ 5,400
Unamortized discount and issuance costs						$ 500			$ 500
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| Debt Instrument, Quarterly Periodic Payment, Period One
Line of Credit Facility [Line Items]
Term loan, first quarterly principal payment due in					33 months
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| Three-month LIBOR
Line of Credit Facility [Line Items]
Basis spread on floating interest rate					7.50%
Interest rate						10.85%			10.85%
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| LIBOR
Line of Credit Facility [Line Items]
Debt instrument, floor rate					2.00%
Debt instrument, cap rate					3.35%
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Line of Credit Facility [Line Items]
Debt instrument, cap rate	3.35%
Interest rate						10.85%			10.85%
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| Tranche A
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity					$ 80,000
Line of credit, maximum borrowing capacity, number of available tranches \| tranche					2
Proceeds from line of credit, net				$ 77,300
Biopharma Credit Investments V (Master) LP \| Keryx \| Term Loan \| Collateral Agent, Pharmakon \| Tranche B
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity					$ 20,000
Proceeds from line of credit, net			$ 20,000

FAIR VALUE OF FINANCIAL INSTRUMENTS - Assets Measured or Disclosed at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Long-term liability:
Embedded debt derivative	$ 760	$ 760
Fair value measurements recurring
Cash equivalents:
Money market funds	17,929	52,442
Long-term liability:
Embedded debt derivative	760	760
Fair value measurements recurring \| Level 1
Cash equivalents:
Money market funds	17,929	52,442
Long-term liability:
Embedded debt derivative	0	0
Fair value measurements recurring \| Level 2
Cash equivalents:
Money market funds	0	0
Long-term liability:
Embedded debt derivative	0	0
Fair value measurements recurring \| Level 3
Cash equivalents:
Money market funds	0	0
Long-term liability:
Embedded debt derivative	$ 760	$ 760

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(4)
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-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
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-URI https://asc.fasb.org//1943274/2147480524/946-210-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section S99
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
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-Paragraph 5C
-Subparagraph (SX 210.12-13C(Column H)(Footnote 7))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5C

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(9)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479617/946-210-S99-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 5
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/exampleRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-10

+ Details

INTANGIBLE ASSET AND GOODWILL (Tables)

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

Intangible asset, net of accumulated amortization, prior impairments and adjustments as of June 30, 2023 and December 31, 2022 consisted of the following (in thousands):


	Three Months Ended June 30, 2023						December 31, 2022
Intangible asset:	Gross Carrying Value		Accumulated Amortization		Net Book Value		Net Book Value		Estimated Useful Life
Developed product rights for Auryxia	$	214,705	$	(160,642)	$	54,063	$	72,084	6 years

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Jun. 30, 2023	Dec. 31, 2022
Stock Options
Outstanding beginning balance (in shares)		11,775,411
Granted (in shares)		3,514,813
Exercised (in shares)	(142,440)	0
Canceled and forfeited (in shares)		(1,130,737)
Outstanding ending balance (in shares)		14,153,498	11,775,411
Options exercisable at end of period (in shares)		7,800,000
Weighted Average Exercise Price
Outstanding beginning balance (in dollars per share)		$ 5.82
Granted (in dollars per share)		0.69
Exercised (in dollars per share)		0
Canceled and forfeited (in dollars per share)		6.35
Outstanding ending balance (in dollars per share)		4.50	$ 5.82
Options exercisable at end of period, weighted-average exercise price (in dollars per share)		$ 6.64
Weighted-Average Remaining Contractual Life (years)
Options outstanding, weighted-average remaining contractual life (in years)		7 years 3 months 29 days	7 years 3 months 3 days
Options exercisable at end of period, weighted-average remaining contractual life (in years)		6 years 3 days
Options outstanding, aggregate intrinsic value		$ 1,435,662

NATURE OF BUSINESS (Details) $ in Thousands	Jun. 30, 2023 USD ($) commercial_product	Dec. 31, 2022 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of commercial products \| commercial_product	1
Cash and cash equivalents \| $	$ 53,572	$ 90,466

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Restricted Stock Units Activity (Details) - Service-Based Restricted Stock Units	6 Months Ended
	Jun. 30, 2023 $ / shares shares
2014 Stock Incentive Plan
Shares
Outstanding beginning balance (in shares) \| shares	5,674,406
Granted (in shares) \| shares	2,759,675
Forfeited and canceled (in shares) \| shares	(564,606)
Outstanding ending balance (in shares) \| shares	7,869,475
Weighted- Average Grant Date Fair Value
Outstanding beginning balance, weighted average fair value (in dollars per share) \| $ / shares	$ 2.10
Granted, weighted average fair value (in dollars per share) \| $ / shares	0.68
Forfeited and canceled, weighted average fair value (in dollars per share) \| $ / shares	1.00
Outstanding ending balance, weighted average fair value (in dollars per share) \| $ / shares	$ 1.30
2023 Stock Incentive Plan
Shares
Granted (in shares) \| shares	210,000
Outstanding ending balance (in shares) \| shares	210,000
Weighted- Average Grant Date Fair Value
Granted, weighted average fair value (in dollars per share) \| $ / shares	$ 1.20
Outstanding ending balance, weighted average fair value (in dollars per share) \| $ / shares	$ 1.20

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

6 Months Ended

Jun. 30, 2023

Payables and Accruals [Abstract]

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES

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


	June 30, 2023		December 31, 2022
Product revenue allowances	$	23,303	$	26,268
Product return reserves, current portion	4,626		7,789
Clinical trial costs	754		5,755
Compensation and related benefits	6,582		11,481
Operating lease liabilities, current portion	4,757		4,744
Royalties	3,198		3,804
Professional fees	2,800		1,886
Accrued manufacturing costs	5,578		4,310
Restructuring costs	334		2,751
Other	4,476		6,989
Total accrued expenses and other current liabilities	$	56,408	$	75,777

Accrued manufacturing costs includes the costs associated with the Company's commercial product Auryxia and vadadustat for which the Company is seeking approval from the FDA to market in the U.S. and for which the Company recently signed a license agreement with Medice to market in Europe and other territories (see Note 5 for further details).

LIABILITY RELATED TO SALE OF FUTURE ROYALTIES - Additional Information (Details) - USD ($) $ in Thousands	Feb. 25, 2021	Jun. 30, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Maximum annual royalty payout capacity	$ 13,000
Maximum aggregate royalty payout capacity	150,000
Proceeds from sale of future royalties, net	44,800
Liability related to sale of future royalties	$ 44,800	$ 56,548	$ 57,484
Annual effective interest rate		0.00%

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net loss	$ (11,172)	$ (26,878)	$ 29,449	$ (63,509)	$ (38,050)	$ (34,058)	$ (282,024)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

LICENSE, COLLABORATION AND OTHER REVENUE

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

LICENSE, COLLABORATION AND OTHER REVENUE

The Company recognized the following revenues from its license, collaboration and other revenue agreements (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
License, collaboration and other revenue:	2023		2022		2023		2022
MTPC Collaboration Agreement	$	516	$	434	$	4,678	$	8,398
Otsuka U.S. Agreement	2,225		81,135		2,225		86,773
Otsuka International Agreement	—		—		—		5,503
Total collaboration revenue	$	2,741	$	81,569	$	6,903	$	100,674
JT and Torii Sublicense Agreement	1,391		1,487		2,528		2,633
Medice License Agreement	10,000		—		10,000		—
Total license, collaboration and other revenue	$	14,132	$	83,056	$	19,431	$	103,307

The following table presents changes in the Company’s contract assets and liabilities (in thousands):


	Six Months Ended June 30, 2023
	Balance at Beginning of Period		Additions		Deductions		Balance at End of Period
Contract assets:
Accounts receivable(1)	$	1,901	$	943	$	(2,319)	$	525
Prepaid expenses and other current assets	$	781	$	—	$	(781)	$	—
Contract liability:
Deferred revenue	$	47,034	$	—	$	(3,738)	$	43,296

	Six Months Ended June 30, 2022
	Balance at Beginning of Period		Additions		Deductions		Balance at End of Period
Contract assets:
Accounts receivable(1)	$	19,094	$	92,146	$	(54,614)	$	56,626
Prepaid expenses and other current assets	$	4,309	$	9,550	$	(4,309)	$	9,550
Contract liabilities:
Deferred revenue	$	42,380	$	65,042	$	(59,079)	$	48,343
Accounts payable	$	3,171	$	—	$	(3,171)	$	—

(1) Excludes accounts receivable related to amounts due to the Company from product sales of Auryxia which are included in the accompanying unaudited condensed consolidated balance sheet as of June 30, 2023 and 2022.

The Company recognized the following revenues as a result of changes in the contract asset and contract liability balances in the respective periods (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
Revenue Recognized in the Period:	2023		2022		2023		2022
Deferred revenue — beginning of the period	$	—	$	15,503	$	—	$	22,105

During the three and six months ended June 30, 2023 and 2022, the Company recognized no revenue from performance obligations satisfied in previous periods.

MTPC Collaboration Agreement

On December 11, 2015, the Company and MTPC entered into the MTPC Agreement, providing MTPC with exclusive development and commercialization rights to vadadustat in Japan and certain other Asian countries (collectively, the MTPC Territory), which was amended effective as of December 2, 2022. In addition, the Company supplies vadadustat to MTPC for both clinical and commercial use in the MTPC Territory. In February 2021, the Company entered into the Royalty Agreement

with HCR, whereby the Company sold its right to receive royalties and sales milestones under the MTPC Agreement, subject to certain caps and other terms and conditions (see Note 6 for additional information). See Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for a more detailed description of the MTPC Agreement.

The Company identified two performance obligations in connection with its material promises under the MTPC Agreement as follows: (i) License, Research and Clinical Supply Performance Obligation and (ii) Rights to Future Know-How Performance Obligation. The Company allocates the transaction price to each performance obligation based on the Company’s best estimate of the relative standalone selling price. The Company developed a best estimate of the standalone selling price for the Rights to Future Know-How Performance Obligation primarily based on the likelihood that additional intellectual property covered by the license conveyed will be developed during the term of the arrangement and determined it is immaterial. As such, the Company did not develop a best estimate of standalone selling price for the License, Research and Clinical Supply Performance Obligation and allocated the entire transaction price to this performance obligation. The deliverables associated with the License, Research and Clinical Supply Performance Obligation were satisfied as of June 30, 2018.

As of June 30, 2023, the transaction price was comprised of: (i) the up-front payment of $20.0 million, (ii) the cost for the Phase 2 studies of $20.5 million, (iii) the cost of all clinical supply provided to MTPC for the Phase 3 studies, (iv) $10.0 million in development milestones received, (v) $25.0 million in regulatory milestones received, comprised of $10.0 million relating to the NDA filing in Japan and $15.0 million relating to regulatory approval of vadadustat in Japan, and (vi) $4.0 million in royalties from net sales of Vafseo. As of June 30, 2023, all development milestones and $25.0 million in regulatory milestones have been achieved. No other regulatory milestones have been assessed as probable of being achieved and as a result have been fully constrained. The Company re-evaluates the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. Revenue for the License, Research and Clinical Supply Performance Obligation for the MTPC Agreement is being recognized using a proportional performance method, for which all deliverables have been completed. During the three and six months ended June 30, 2023, the Company recognized revenue from MTPC royalties totaling approximately $0.5 million and $0.9 million, respectively, and approximately $0.4 million and $0.7 million during the three and six months ended June 30, 2022, respectively. As noted above, in February 2021, the Company entered into the Royalty Agreement, whereby the Company sold its right to receive these royalties and sales milestones under the MTPC Agreement, subject to certain caps and other terms and conditions (see Note 6 for additional information). The revenue is classified as license, collaboration and other revenue in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss. As of June 30, 2023, there were no accounts receivable, no deferred revenue, and no contract assets. There were no asset or liability balances classified as long-term in the unaudited condensed consolidated balance sheet as of June 30, 2023.

Supply of Drug Product to MTPC

On July 15, 2020, the Company and its collaboration partner MTPC entered into a supply agreement (MTPC Supply Agreement). The MTPC Supply Agreement includes the terms and conditions under which the Company will supply vadadustat drug product to MTPC for commercial use in Japan and certain other Asian countries, as contemplated by the MTPC Agreement. See Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for a more detailed description of this supply agreement.

On December 16, 2022, the Company, MTPC, and Esteve Química, S.A. (Esteve) executed an Assignment of Supply Agreement (Esteve Assignment Agreement), pursuant to which the Supply Agreement between the Company and Esteve (Esteve Agreement) (see Note 13) was assigned to MTPC. The Esteve Assignment Agreement transferred the rights and obligations of the Company under the Esteve Agreement to MTPC, including the obligations under certain purchase orders issued by the Company and accepted by Esteve. As such, the transferred purchase orders will continue to have a binding effect on MTPC to take delivery of the product from Esteve in accordance with the terms of the Esteve Agreement. The Company will have no further obligation to take delivery of, or pay for, product delivered by Esteve under the transferred purchase orders.

The Company recognized no revenue and $3.7 million in revenue under the MTPC Supply Agreement during the three and six months ended June 30, 2023, respectively, and no revenue and $7.6 million during the three and six months ended June 30, 2022, respectively. As of June 30, 2023, the Company recorded no accounts receivable, deferred revenue or other current liabilities.

Cyclerion License Agreement

On June 4, 2021, the Company entered into a License Agreement (Cyclerion Agreement) with Cyclerion Therapeutics Inc. (Cyclerion), pursuant to which Cyclerion granted the Company an exclusive global license under certain intellectual property rights to research, develop and commercialize praliciguat, an investigational oral soluble guanylate stimulator.

Under the terms of the Cyclerion Agreement, the Company made an upfront payment of $3.0 million in cash to Cyclerion, which was paid and recorded to research and development expense in June 2021. Substantially all of the fair value of the assets acquired in conjunction with the Cyclerion Agreement was concentrated in the acquired license. As a result, the Company accounted for this transaction as an asset acquisition under ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The upfront payment was charged to expense at acquisition, as it relates to a development stage compound with no alternative future use. In addition, Cyclerion is eligible to receive up to an aggregate of $222.0 million from the Company in specified development and regulatory milestone payments on a product-by-product basis. Cyclerion will also be eligible to receive specified commercial milestones as well as tiered royalties ranging from a low-single-digit- to mid-double-digit percentage of net sales, on a product-by-product basis, and subject to reduction upon expiration of patent rights or the launch of a generic product in the territory. A more detailed description of this agreement can be found in Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A.

CSL Vifor License Agreement

On May 12, 2017, the Company entered into a License Agreement (Vifor Agreement) with Vifor (International) Ltd. (now a part of CSL Limited) (CSL Vifor), pursuant to which the Company granted CSL Vifor an exclusive license to sell vadadustat solely to Fresenius Kidney Care Group LLC, an affiliate of Fresenius Medical Care North America (FMCNA) in the United States. On April 8, 2019, the Company and CSL Vifor entered into an Amended and Restated License Agreement (Vifor First Amended Agreement), which amended and restated in full the Vifor Agreement. On February 18, 2022, the Company and CSL Vifor entered into a Second Amended and Restated License Agreement (Vifor Second Amended Agreement), which amends and restates the Vifor First Amended Agreement.

Pursuant to the Vifor Second Amended Agreement, the Company granted CSL Vifor an exclusive license to sell vadadustat to FMCNA and its affiliates, including Fresenius Kidney Care Group LLC, to certain third party dialysis organizations approved by the Company, to independent dialysis organizations that are members of certain group purchasing organizations, and to certain non-retail specialty pharmacies (collectively, the Supply Group) in the United States (Vifor Territory). Pursuant to the Vifor Second Amended Agreement, CSL Vifor agreed that it would not sell or otherwise supply vadadustat until the FDA has granted regulatory approval for vadadustat for the treatment of anemia due to CKD in adult patients with DD-CKD in the Vifor Territory and until CSL Vifor has entered a supply agreement with the applicable member of the Supply Group.

Similar to the Vifor First Amended Agreement, the Vifor Second Amended Agreement is structured as a profit share arrangement between the Company and CSL Vifor in which the Company will receive approximately 66% of the profit, net of certain pre-specified costs. Under the Vifor Second Amended Agreement, CSL Vifor made an upfront payment to the Company of $25.0 million in lieu of the previously disclosed milestone payment of $25.0 million that CSL Vifor was to pay the Company following approval of vadadustat by the FDA, as established under the Vifor First Amended Agreement.

Unless earlier terminated, the Vifor Second Amended Agreement will expire upon the later of the expiration of all patents that claim or cover vadadustat or expiration of marketing or regulatory exclusivity for vadadustat in the Vifor Territory. CSL Vifor may terminate the Vifor Second Amended Agreement in its entirety upon 30 months' prior written notice after the first anniversary of the receipt of regulatory approval, if approved from the FDA for vadadustat for dialysis-dependent CKD patients. The Company may terminate the Vifor Second Amended Agreement in its entirety for convenience, following the earlier of a certain period of time elapsing or following certain specified regulatory events, and upon six months’ prior written notice. If the Company so terminates for convenience, subject to specified exceptions, the Company will pay a termination fee to CSL Vifor. In addition, either party may, subject to a cure period, terminate the Vifor Second Amended Agreement in the event of the other party’s uncured material breach or bankruptcy.

Investment Agreement

In connection with the Vifor Agreement, in May 2017, the Company and CSL Vifor entered into an investment agreement (First Investment Agreement), pursuant to which the Company sold an aggregate of 3,571,429 shares of the Company’s common stock (2017 Shares) to CSL Vifor at a price per share of $14.00 for a total of $50.0 million. The amount representing the premium over the closing stock price of $12.69 on the date of the transaction, totaling $4.7 million, was determined by the Company to represent consideration related to the Vifor Agreement.

CSL Vifor agreed to a lock-up restriction such that it agreed not to sell the 2017 Shares for a period of time following the effective date of the First Investment Agreement as well as a customary standstill agreement. In addition, the First Investment Agreement contains voting agreements made by CSL Vifor with respect to the 2017 Shares. The 2017 Shares have not been registered pursuant to the Securities Act of 1933, as amended, or the Securities Act, and were issued and sold in reliance upon the exemption from registration contained in Section 4(a)(2) of the Securities Act and Rule 506 promulgated thereunder.

In connection with entering into the Vifor Second Amended Agreement, on February 18, 2022, the Company and CSL Vifor entered into an investment agreement (Second Investment Agreement), pursuant to which the Company sold an aggregate of 4,000,000 shares of its common stock (2022 Shares) to CSL Vifor for a total of $20 million on February 22, 2022. The amount representing the premium over the grant date fair value on the date of the transaction, $13.6 million, was determined by the Company to represent the consideration related to the Vifor Second Amended Agreement. CSL Vifor has agreed to a lock-up restriction to not sell or otherwise dispose of the 2022 Shares for a period of time following the effective date of the Second Investment Agreement as well as a customary standstill agreement. In addition, the Second Investment Agreement contains voting agreements made by CSL Vifor with respect to the 2022 Shares. The 2022 Shares have not been registered pursuant to the Securities Act and were issued and sold in reliance upon the exemption from registration contained in Section 4(a)(2) of the Securities Act and/or Rule 506 promulgated thereunder, as the transaction did not involve any public offering within the meaning of Section 4(a)(2) of the Securities Act. See Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for a more detailed description of the Vifor Second Amended Agreement.

Revenue Recognition

The Company identified one performance obligation in connection with its obligations under the Vifor Second Amended Agreement, the License Deliverable, or License Performance Obligation. The transaction price at inception was comprised of: (i) the up-front payment of $25.0 million, (ii) the premium paid by CSL Vifor on the First Investment Agreement of $4.7 million, and (iii) the premium paid by CSL Vifor on the Second Investment Agreement of $13.6 million. Pursuant to the terms of the Vifor Second Amended Agreement, these payments from CSL Vifor are non-refundable and non-creditable against any other amount due to the Company. Also pursuant to the Vifor Second Amended Agreement, if the Centers for Medicare & Medicaid Services (CMS) determines that vadadustat is excluded from the Transitional Drug Add-on Payment Adjustment (TDAPA), the Company can terminate the Vifor Second Amended Agreement and will be required to repay the up-front payment and the premiums paid by CSL Vifor in the First Investment Agreement and Second Investment Agreement, respectively. CSL Vifor also agreed that it will not sell or otherwise supply vadadustat until the FDA has granted regulatory approval for vadadustat for the treatment of anemia due to CKD in adult patients with DD-CKD. The Company constrains the variable consideration to an amount for which a significant revenue reversal is not probable. Therefore, the Company determined that the entire transaction price at inception was constrained under ASC 606, and the Company has recorded the transaction price of $43.3 million to long-term deferred revenue as of June 30, 2023.

Refund Liability to Customer

Pursuant to the Vifor Second Amended Agreement, CSL Vifor contributed $40.0 million to a working capital fund established to partially fund the Company’s costs of purchasing vadadustat from its contract manufacturers (Working Capital Fund), which amount of funding will fluctuate, and which funding the Company is required to repay to CSL Vifor over time. The $40 million initial contribution to the Working Capital Fund represents 50% of the amount of purchase orders that the Company has placed with its contract manufacturers for the supply of vadadustat for the Vifor Territory already delivered as of the effective date of the Vifor Second Amended Agreement, and to be delivered through the end of 2023. The amount of the Working Capital Fund will be reviewed at specified intervals and is adjusted based on a number of factors including outstanding supply commitments for vadadustat for the Vifor Territory and agreed upon vadadustat inventory levels held by the Company for the Vifor Territory. Upon termination or expiration of the Vifor Second Amended Agreement for any reason other than convenience by CSL Vifor (including following receipt of the CRL for vadadustat), the Company will be required to refund the outstanding balance of the Working Capital Fund on the date of termination or expiration.

The Company has recorded the Working Capital Fund as a refund liability under ASC 606. The Company has determined that the refund liability itself does not represent an obligation to transfer goods or services to CSL Vifor in the future. The Company has therefore determined that this refund liability is not a contract liability under ASC 606. The Company accounted for the refund liability as a debt arrangement with zero coupon interest. The Company imputed interest on the refund liability to the customer at a rate of 15.0% per annum, which was determined based on certain factors, including the Company's credit rating, comparable securities yield, and the expected repayment period of the Working Capital Fund. The Company recorded an initial discount on the refund liability to the customer and a corresponding deferred gain to the refund liability to customer on the condensed consolidated balance sheet as of the date the funds were received from CSL Vifor, which was March 18, 2022. The discount on the note payable is being amortized to interest expense using the effective interest method over the expected term of

the refund liability. The deferred gain is being amortized to interest income on a straight-line basis over the expected term of the refund liability. The amortization of the discount was $0.9 million and $1.7 million for the three and six months ended June 30, 2023, respectively, and $1.1 million for the three and six months ended June 30, 2022. The amortization of the deferred gain was $1.0 million and $2.0 million for the three and six months ended June 30, 2023, respectively, and $0.8 million for the three and six months ended June 30, 2022. As of June 30, 2023, the $40.6 million total refund liability is classified as a long-term refund liability based on management's estimate of potential amounts that could be refundable exceeding a one-year period.

Panion License Agreement

The Company had a license agreement, which was amended from time to time, with Panion & BF Biotech, Inc. (Panion), under which Keryx, the Company's wholly owned subsidiary, was the contracting party (Panion License Agreement), pursuant to which Keryx in-licensed the exclusive worldwide rights, excluding certain Asian-Pacific countries (Licensor Territory) for the development and commercialization of ferric citrate.

On April 17, 2019, the Company and Panion entered into a second amended and restated license agreement (Panion Amended License Agreement), which amends and restates in full the Panion License Agreement, effective as of April 17, 2019. The Panion Amended License Agreement provides Keryx with an exclusive license under Panion-owned know-how and patents with the right to sublicense, develop, make, use, sell, offer for sale, import and export ferric citrate worldwide, excluding the Licensor Territory. The Panion Amended License Agreement also provides Panion with an exclusive license under the Keryx-owned patents, with the right to sublicense (with the Company’s written consent), develop, make, use, sell, offer for sale, import and export ferric citrate in certain countries in the Licensor Territory. Under the Panion Amended License Agreement, Panion is eligible to receive from the Company or any sublicensee royalty payments based on a mid-single digit percentage of sales of ferric citrate in the Company’s licensed territories. The Company is eligible to receive from Panion or any sublicensee royalty payments based on a mid-single digit percentage of net sales of ferric citrate in Panion’s licensed territories. See Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for a more detailed description of this license agreement.

The Company recognized royalty payments due to Panion of approximately $3.2 million and $6.0 million during the three and six months ended June 30, 2023, respectively, and $3.5 million and $6.6 million during the three and six months ended June 30, 2022, respectively, relating to the Company’s sales of Auryxia in the United States and JT and Torii’s net sales of Riona in Japan, as the Company is required to pay a mid-single digit percentage of net sales of ferric citrate in the Company’s licensed territories to Panion under the terms of the Panion Amended License Agreement.

JT and Torii Sublicense Agreement

The Company has an Amended and Restated Sublicense Agreement, which was amended in June 2013, with JT and Torii (JT and Torii Sublicense Agreement), under which Keryx, the Company’s wholly owned subsidiary, remains the contracting party. Under the JT and Torii Sublicense Agreement, JT and Torii obtained the exclusive sublicense rights for the development and commercialization of ferric citrate hydrate in Japan. JT and Torii are responsible for the future development and commercialization costs in Japan. See Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for a more detailed description of this sublicense agreement.

The Company identified two performance obligations in connection with its obligations under the JT and Torii Sublicense Agreement: (i) License and Supply Performance Obligation and (ii) Rights to Future Know-How Performance Obligation. The Company allocated the transaction price to each performance obligation based on the Company’s best estimate of the relative standalone selling price. The Company developed a best estimate of the standalone selling price for the Rights to Future Know-How Performance Obligation primarily based on the likelihood that additional intellectual property covered by the license conveyed will be developed during the term of the arrangement and determined it immaterial. As such, the Company did not develop a best estimate of standalone selling price for the License and Supply Performance Obligation and allocated the entire transaction price to this performance obligation.

The Company recognized license revenue of $1.4 million and $2.5 million during the three and six months ended June 30, 2023, respectively, and $1.5 million and $2.6 million during the three and six months ended June 30, 2022, respectively, related to royalties earned on net sales of Riona in Japan. The Company records the associated mid-single digit percentage of net sales royalty expense due to Panion, the licensor of Riona, in the same period as the royalty revenue from JT and Torii is recorded.

Averoa License Agreement

On December 22, 2022, the Company and Averoa SAS (Averoa) entered into a license agreement (Averoa License Agreement), pursuant to which the Company granted to Averoa an exclusive license to develop and commercialize ferric citrate (Averoa Licensed Product), in the European Economic Area, Turkey, Switzerland and the United Kingdom (Averoa Territory).

Under the Averoa License Agreement, the Company is entitled to receive tiered, escalating royalties ranging from a mid-single digit percentage to a low double-digit percentage of Averoa's annual net sales in the Averoa Territory, including certain minimum royalty amounts in certain years, and subject to reduction in certain circumstances. The Company and Averoa will establish a joint steering committee to oversee the development, manufacturing and commercialization of the Averoa Licensed Product in the Averoa Territory. The Averoa License Agreement expires on the date of expiration of all royalty obligations due thereunder with respect to the Averoa Licensed Product on a country-by-country basis in the Averoa Territory, unless earlier terminated in accordance with the agreement.

The Averoa License Agreement provides that the Company and Averoa will enter into a supply agreement pursuant to which the Company will supply the Averoa Licensed Product to Averoa for commercial use in the Averoa Territory. The Company will have the right to terminate the supply agreement upon 24 months' notice, which may be provided on or after January 1, 2024. The Company did not receive any consideration under this agreement as of June 30, 2023. A more detailed description of this license agreement can be found in Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A.

Medice License Agreement

On May 24, 2023 (Medice Effective Date), the Company and MEDICE Arzneimittel Pütter GmbH & Co. KG (Medice) entered into a license agreement (Medice License Agreement), pursuant to which the Company granted to Medice an exclusive license to develop and commercialize vadadustat (Medice Licensed Product) for the treatment of anemia in adult patients with chronic kidney disease in the European Economic Area, the United Kingdom, Switzerland and Australia (Medice Territory).

Under the Medice License Agreement, the Company is entitled to receive the following payments:

(i) an up-front payment of $10.0 million,

(ii) commercial milestone payments up to an aggregate of $100.0 million, and

(iii) tiered royalties ranging from 10% to 30% of Medice's annual net sales of the Medice Licensed Product in the Medice Territory, subject to reduction in certain circumstances.

The royalties will expire on a country-by-country basis upon the latest to occur of (a) the date of expiration of the last-to-expire valid claim of any Company, Medice, or joint patent that covers the Medice Licensed Product in such country in the Medice Territory, (b) the date of expiration of data or regulatory exclusivity for the Medice Licensed Product in such country in the Medice Territory, and (c) the date that is 12 years from first commercial sale of the Medice Licensed Product in such country in the Medice Territory.

Under the Medice License Agreement, the Company retains the right to develop the Medice Licensed Product for non-dialysis patients with anemia due to chronic kidney disease in the Medice Territory. If the Company develops the Medice Licensed Product for non-dialysis patients and such Medice Licensed Product receives marketing approval in the Medice Territory, Medice will commercialize the Medice Licensed Product for both indications in the Medice Territory. In this instance, the Company would receive 70% of the net product margin of any sales of the Medice Licensed Product in the non-dialysis patient population, unless Medice requests to share the cost of the development necessary to gain approval to market the Medice Licensed Product for non-dialysis patients in the Medice Territory and the parties agree on alternative financial terms. If the Company develops the licensed product for non-dialysis patients, the Company has determined that the activities under the Medice License Agreement represent joint operating activities in which both parties are active participants and of which both parties are exposed to significant risks and rewards that are dependent on the success of the activities. Accordingly, if the Company develops the Medice Licensed Product for non-dialysis patients the Company will account for the joint activities in accordance with ASC No. 808, Collaborative Arrangements (ASC 808). Additionally, the Company has determined that in the context of the development of the Medice Licensed Product for non-dialysis patients, Medice does not represent a customer as contemplated by ASC 606-10-15, Revenue from Contracts with Customers – Scope and Scope Exceptions. As a result, the activities conducted pursuant to development activities for the Medice Licensed Product for non-dialysis patients will be accounted for as a component of the related expense in the period incurred.

The Company and Medice will establish a joint steering committee to oversee the development and commercialization of the Medice Licensed Product in the Medice Territory.

The Medice License Agreement expires on the date of expiration of all payment obligations due thereunder with respect to the Medice Licensed Product in the last country in the Medice Territory, unless earlier terminated in accordance with the terms of the Medice License Agreement. Either party may, subject to a cure period, terminate the Medice License Agreement in the event of the other party's uncured material breach. Medice has the right to terminate the Medice License Agreement in its

entirety for convenience upon 12 months' prior written notice delivered on or after the date that is 12 months after the Medice Effective Date.

The Medice License Agreement includes customary terms relating to, among others, indemnification, confidentiality, remedies, and representations and warranties. The Medice License Agreement provides that the Company and Medice will enter into a supply agreement pursuant to which the Company will supply the Medice Licensed Product to Medice for commercial use in the Medice Territory.

Revenue Recognition

The Company evaluated the elements of the Medice License Agreement in accordance with the provisions of ASC 606 and concluded the contract counterparty, Medice, is a customer. The Company's arrangement with Medice contains one material promise under the contract at inception, which is the exclusive license under the Company's intellectual property to develop and commercialize the Medice Licensed Product in the Medice Territory during the term of the Medice License Agreement and use the Akebia Trademark solely in connection with the commercialization of the Medice Licensed Product (License Deliverable).

The Company identified one performance obligation in connection with its obligations under the Medice License Agreement, which is the License Deliverable (License Performance Obligation). The transaction price at inception was comprised of the up-front payment of $10.0 million, of which the Company received $8.6 million as of June 30, 2023. The remaining $1.4 million was withheld by the German Federal Tax Office and was recorded to other long-term assets on the condensed consolidated balance sheet as of June 30, 2023. The Company allocated the up-front payment of $10.0 million to the License Performance Obligation. Pursuant to the terms of the Medice License Agreement, this payment from Medice is non-refundable and non-creditable against any other amount due to the Company. In accordance with ASC 606, the Company will recognize sales-based royalties and milestone payments based on the level of sales, when the related sales occur as these amounts have been determined to relate to the license granted to Medice and therefore are recognized at the later of when the performance obligation is satisfied, or the related sales occur.

The License Performance Obligation was satisfied as of the Medice Effective Date of the Medice License Agreement. As such, the Company recognized the $10.0 million up-front payment as License, collaboration, and other revenue in the condensed consolidated statement of operations and comprehensive income (loss) during the three and six months ended June 30, 2023.

Past Collaboration and License Agreements

U.S. Collaboration and License Agreement with Otsuka Pharmaceutical Co. Ltd.

On December 18, 2016, the Company entered into a collaboration and license agreement with Otsuka (Otsuka U.S. Agreement). The collaboration was focused on the development and commercialization of vadadustat in the United States. The Company was responsible for leading the development of vadadustat, for which it submitted an NDA to the FDA in March 2021, and for which it received the CRL in March 2022. On May 12, 2022, the Company received notice from Otsuka that Otsuka had elected to terminate the Otsuka U.S. Agreement and the April 25, 2017 collaboration and license agreement with Otsuka (Otsuka International Agreement).

On June 30, 2022, the Company and Otsuka entered into the Termination Agreement, pursuant to which, among other things, the Company and Otsuka agreed to terminate the Otsuka U.S. Agreement and the Otsuka International Agreement as of June 30, 2022.

During the three and six months ended June 30, 2022, the Company recognized collaboration revenue totaling $81.1 million and $86.8 million, respectively, with respect to the Otsuka U.S. Agreement. During the three months ended June 30, 2023, the Company recognized $2.2 million in collaboration revenue in connection with the Packaging Validation Transfer Agreement entered into with Otsuka on April 20, 2023. The Company evaluated the agreement under ASC 606 and concluded it was closely tied to the prior collaboration revenue agreements and under ASC606 recognized collaboration revenue in the current quarter. A more detailed description of the Otsuka U.S. Agreement can be found in Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A.

International Collaboration and License Agreement with Otsuka Pharmaceutical Co. Ltd.

On April 25, 2017, the Company entered into the Otsuka International Agreement. The collaboration was focused on the development and commercialization of vadadustat in Europe, Russia, China, Canada, Australia, the Middle East and certain other territories (collectively, the Otsuka International Territory). As discussed above, the Otsuka International Agreement was terminated on June 30, 2022 pursuant to the Termination Agreement.

During the three and six months ended June 30, 2022, the Company recognized no collaboration revenue and $5.5 million with respect to the Otsuka International Agreement, respectively. A more detailed description of this collaboration agreement and the Company's evaluation of this agreement under ASC 606 can be found in Note 5 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A.

LICENSE, COLLABORATION AND OTHER REVENUE - Cyclerion License Agreement (Details) - Cyclerion Therapeutics License Agreement $ in Millions	Jun. 04, 2021 USD ($)
Asset Acquisition [Line Items]
Upfront payment for asset acquisition	$ 3.0
Contingent consideration from developmental and regulatory milestones	$ 222.0

INTANGIBLE ASSET AND GOODWILL - Intangible Assets (Details) - Developed product rights for Auryxia - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 214,705
Accumulated Amortization	(160,642)
Net Book Value	$ 54,063	$ 72,084
Estimated Useful Life	6 years

LICENSE, COLLABORATION AND OTHER REVENUE - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Accounts receivable
Contract assets:
Balance at Beginning of Period	$ 1,901	$ 19,094
Additions	943	92,146
Deductions	(2,319)	(54,614)
Balance at End of Period	525	56,626
Prepaid expenses and other current assets
Contract assets:
Balance at Beginning of Period	781	4,309
Additions	0	9,550
Deductions	(781)	(4,309)
Balance at End of Period	0	9,550
Deferred revenue
Contract liability:
Balance at Beginning of Period	47,034	42,380
Additions	0	65,042
Deductions	(3,738)	(59,079)
Balance at End of Period	$ 43,296	48,343
Accounts payable
Contract liability:
Balance at Beginning of Period		3,171
Additions		0
Deductions		(3,171)
Balance at End of Period		$ 0

PRODUCT REVENUE AND RESERVES FOR VARIABLE CONSIDERATION

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

PRODUCT REVENUE AND RESERVES FOR VARIABLE CONSIDERATION

To date, the Company’s only source of product revenue has been from the U.S. sales of Auryxia. Total net product revenue was $42.2 million and $43.3 million for the three months ended June 30, 2023 and 2022, respectively, and $77.0 million and $84.7 million for the six months ended June 30, 2023 and 2022, respectively. Product revenue allowance and reserve categories were as follows:


(in thousands)	Chargebacks and Discounts		Rebates, Fees and other Deductions		Product Returns		Total
Balance at December 31, 2022	$	1,259	$	30,043	$	10,923	$	42,225
Current provisions related to sales in current year	5,216		37,270		2,462		44,948
Adjustments related to prior year sales	(8)		(473)		—		(481)
Credits/payments made	(5,616)		(41,474)		(5,510)		(52,600)
Balance at June 30, 2023	$	851	$	25,366	$	7,875	$	34,092

(in thousands)	Chargebacks and Discounts		Rebates, Fees and other Deductions		Product Returns		Total
Balance at December 31, 2021	$	1,047	$	27,100	$	10,065	$	38,212
Current provisions related to sales in current year	4,965		42,562		2,735		50,262
Adjustments related to prior year sales	131		784		—		915
Credits/payments made	(5,236)		(43,803)		(2,968)		(52,007)
Balance at June 30, 2022	$	907	$	26,643	$	9,832	$	37,382

Chargebacks, discounts and estimated product returns are recorded as a reduction of revenue in the period the related product revenue is recognized in the unaudited condensed consolidated statement of operations and comprehensive income (loss). Chargebacks are recorded as a reduction to accounts receivable while discounts, rebates, fees and other deductions are recorded with a corresponding increase to accrued expenses and other current liabilities or accounts payable on the unaudited condensed consolidated balance sheets. Estimated product returns for the period related to product sales are recorded as other long-term liabilities in the unaudited condensed consolidated balance sheet.

Accounts receivable, net related to product sales, was approximately $18.2 million and $37.3 million as of June 30, 2023 and December 31, 2022, respectively.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

LICENSE, COLLABORATION AND OTHER REVENUE - Japan Tobacco, Inc. and Torii Pharmaceutical Co., Ltd. Sublicense Agreement (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) performance_obligation	Jun. 30, 2022 USD ($)
License, collaboration and other revenue:
Recognized revenue	$ 56,376	$ 126,365	$ 96,381	$ 187,988
JT and Torii Sublicense Agreement \| Sublicense Agreement
License, collaboration and other revenue:
Number of performance obligations \| performance_obligation			2
Recognized revenue	$ 1,400	$ 1,500	$ 2,500	$ 2,600

- Definition

+ References

+ Details

LIABILITY RELATED TO SALE OF FUTURE ROYALTIES (Tables)

6 Months Ended

Jun. 30, 2023

Other Liabilities Disclosure [Abstract]

Activity within Liability Related to Sale of Future Royalties, net

The following table shows the activity within the liability account for the six months ended June 30, 2023 (in thousands):


Liability related to sale of future royalties, beginning balance at December 31, 2022	$	57,484
MTPC royalties payable	(936)
Liability related to sale of future royalties, ending balance at June 30, 2023	$	56,548

FAIR VALUE OF FINANCIAL INSTRUMENTS - Additional Information (Details) $ in Thousands	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded debt derivative	$ 760	$ 760
Level 3 \| Measurement Input, Obligations In Loan Agreement Would Not Accelerate Due to Default \| Valuation Technique, Scenario-Based And Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.95	0.95
Collateral Agent, Pharmakon
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded debt derivative	$ 800	$ 800

- Definition

+ References

+ Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

The Company's significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2022, and notes thereto, which are included in the Company's Annual Report on Form 10-K, as amended by Amendment No. 1 on Form 10-K/A that was filed with the Securities and Exchange Commission (SEC) on August 28, 2023 (2022 Annual Report on Form 10-K/A). Since the date of those financial statements, there have been no material changes to the Company's significant accounting policies.

In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the unaudited condensed consolidated financial statements have been included. Interim results for the three and six months ended June 30, 2023 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2023 or any other future period.

Basis of Presentation and Principals of Consolidation

The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (GAAP) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the ASC and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB).

The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Certain monetary amounts, percentages, and other figures included elsewhere in these unaudited condensed consolidated financial statements have been subject to rounding adjustments. Accordingly, figures shown as totals in certain tables may not be the arithmetic aggregation of the figures that precede them, and figures expressed as percentages in the text may not total 100% or, as applicable, when aggregated may not be the arithmetic aggregation of the percentages that precede them.

Segment Information

Operating segments are components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company's chief operating decision maker as of June 30, 2023 was its President and Chief Executive Officer. Based on the criteria established by Accounting Standards Codification 280, Segment Reporting, the Company has one operating and reportable segment, which is the business of developing and commercializing novel therapeutics for people with kidney disease.

Revision of Previously Issued Financial Statements

In connection with the preparation of its consolidated financial statements as of and for the three and six months ended June 30, 2023, the Company identified immaterial prior period errors related to the identification, evaluation and accounting for product returns in its previously issued consolidated financial statements.

In accordance with SAB No. 99, “Materiality,” and SAB No. 108, “Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements,” and as described further in Note 3, Revision of Previously Issued Financial Statements, the Company evaluated the errors and determined the related impacts were not material to its financial statements for the prior year periods when they occurred, but that correcting the errors in the current period would be

significant to the Company's results of operations for the three and six months ended June 30, 2023. Accordingly, the Company has revised previously reported financial information for such immaterial errors. A summary of revisions to certain previously reported financial information presented herein for comparative purposes is included in Note 3, Revision of Previously Issued Financial Statements.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenue and expenses, and the disclosure of contingent assets and liabilities as of and during the reported period. Management bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. In certain circumstances, management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to: prepaid and accrued research and development expense, right-of-use assets and liabilities, embedded debt derivative, refund liabilities to customers, other long-term liabilities, stock-based compensation expense, and certain judgments regarding product and collaboration revenues including various rebates, returns and reserves related to product sales, non-cash interest expense on the liability related to sale of future royalties, inventories, income taxes, intangible asset and goodwill.

Although the Company regularly assesses these estimates, actual results could differ materially from these estimates. Changes in estimates are recorded in the period they become known.

Reconciliation of Cash, Cash Equivalents and Restricted Cash

In determining its cash, cash equivalents and restricted cash, the Company considers only those highly liquid investments, readily convertible to cash which as of June 30, 2023 primarily included funds invested in money market funds. The following table reconciles cash, cash equivalents and restricted cash reported within the Company's consolidated balance sheet to the total amounts showing in the consolidated statement of cash flows:


(in thousands)	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	53,572	$	90,466
Restricted cash included in other long-term assets	1,722		2,703
Total cash, cash equivalents and restricted cash	$	55,294	$	93,169

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating Activities:
Net loss	$ (38,050)	$ (34,058)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	795	833
Amortization of intangible asset	18,021	18,021
Non-cash interest expense related to sale of future royalties	0	4,428
Non-cash royalty revenue related to sale of future royalties	(936)	(764)
Non-cash collaboration revenue	0	(9,550)
Non-cash research and development expense	782	0
Non-cash interest expense	983	916
Non-cash operating lease expense	(955)	(1,198)
Non-cash write-off from termination of lease	(825)	0
Write-down of inventory	612	7,430
Change in excess inventory purchase commitments	0	4,854
Stock-based compensation expense	5,979	11,453
Change in fair value of embedded debt derivative	0	(710)
Changes in operating assets and liabilities:
Accounts receivable	20,712	(30,421)
Inventory	10,828	(4,362)
Prepaid expenses and other current assets	7,684	561
Other long-term assets	(5,876)	10,012
Accounts payable	(12,058)	(8,807)
Accrued expense and other current liabilities	(19,382)	(19,464)
Operating lease liabilities	1,034	1,205
Deferred revenue	(3,738)	5,963
Other long-term liabilities	481	(8,622)
Net cash used in operating activities	(13,909)	(52,280)
Investing Activities:
Purchases of equipment	0	(114)
Net cash used in investing activities	0	(114)
Financing Activities:
Proceeds from refund liabilities to customers	0	40,000
Proceeds from issuance of common stock, net of issuance costs	0	7,102
Proceeds from issuances of stock under employee stock purchase plan	34	367
Proceeds from the exercise of stock options	0	67
Repayments of term debt	(24,000)	0
Net cash (used in) provided by financing activities	(23,966)	47,536
Decrease in cash, cash equivalents and restricted cash	(37,875)	(4,858)
Cash, cash equivalents and restricted cash — beginning of period	93,169	151,839
Cash, cash equivalents and restricted cash — end of period	$ 55,294	$ 146,981

LICENSE, COLLABORATION AND OTHER REVENUE - Panion License Agreement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
JT and Torii Sublicense Agreement \| License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty payments	$ 3.2	$ 3.5	$ 6.0	$ 6.6

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN

Authorized and Outstanding Capital Stock

On June 5, 2020, the Company filed a Certificate of Amendment to its Ninth Amended and Restated Certificate of Incorporation, or its Charter, to increase the number of authorized shares of common stock from 175,000,000 to 350,000,000. As of June 30, 2023, the authorized capital stock of the Company included 350,000,000 shares of common stock, $0.00001 par value per share, of which 188,128,869 and 184,135,714 shares were issued and outstanding as of June 30, 2023 and December 31, 2022, respectively; and 25,000,000 shares of undesignated preferred stock, $0.00001 par value per share, of which no shares were issued and outstanding as of June 30, 2023 and December 31, 2022.

At-the-Market Facility

On April 7, 2022, the Company entered into an Open Market Sale AgreementSM (Sales Agreement), with Jefferies LLC (Jefferies) as agent, for the offer and sale of common stock at current market prices in amounts to be determined from time to time. Also, on April 7, 2022, the Company filed a prospectus supplement relating to the Sales Agreement, pursuant to which it is able to offer and sell under the Sales Agreement up to $26.0 million of its common stock at current market prices from time to time. From the date of filing of the prospectus supplement through the date of the filing of this Quarterly Report on Form 10-Q, the Company has not sold any shares of its common stock under this program.

Terminated At-the-Market Facility

On March 12, 2020, the Company filed a prospectus supplement relating to the Company's sales agreement with Cantor Fitzgerald & Co. (Prior Sales Agreement) pursuant to which it was able to offer and sell up to $65.0 million of its common stock at current market prices from time to time.

On February 25, 2021, the Company filed a prospectus relating to the Prior Sales Agreement with its new shelf registration statement (which replaced the prior shelf registration statement and the sales agreement prospectus supplement), pursuant to which it was able to offer and sell up to $100.0 million of its common stock at current market prices from time to time. On March 1, 2022, the Company filed a prospectus relating to the Prior Sales Agreement, pursuant to which it was authorized to offer and sell up to $25.3 million of its common stock at current market prices from time to time. On March 16, 2022, the

Company terminated the Prior Sales Agreement. During the three months ended March 31, 2022, the Company sold 404,600 shares of common stock under this program with net proceeds (after deducting commissions and other offering expenses) of $0.8 million.

Stock-Based Compensation and Benefit Plans

The Company incurred stock-based compensation expenses of $3.5 million and $6.0 million for the three and six months ended June 30, 2023, respectively and $6.9 million and $11.5 million for the three and six months ended June 30, 2022, respectively.

Equity Incentive Plans

The following table contains information about our equity plans:

June 30, 2023

Title of Plan

Group Eligible

Type of Award Granted (or to be Granted)

Awards Outstanding

Additional Awards Authorized for Grant

Keryx Equity Plans(1)(2)*

Employees, directors and consultants

Stock options and RSUs

287,100

—

Akebia Therapeutics, Inc. Amended and Restated 2008 Equity Incentive Plan (the 2008 Plan)(2)

Employees, directors and consultants

Stock options and RSUs

419

—

Akebia Therapeutics, Inc. 2014 Incentive Plan, as amended (2)

(the 2014 Plan)

(replaces 2008 Plan)

Employees, directors, consultants and advisors

Stock options, RSUs, SARs and performance awards

17,513,530

—

Akebia Therapeutics, Inc. 2023 Stock Incentive Plan (the 2023 Plan)

(replaces 2014 Plan)

Employees, officers, directors, consultants and advisors

Stock options, SARs, restricted stock, unrestricted stock, RSUs, performance awards, other share-based awards and dividend equivalents

549,000

16,256,679

(1) The Keryx Equity Plans consist of the Keryx Biopharmaceuticals, Inc. 1999 Share Option Plan, Keryx Biopharmaceuticals, Inc., as amended, the 2004 Long-Term Incentive Plan, as amended, the Keryx Biopharmaceuticals, Inc. 2007 Incentive Plan, the Keryx Biopharmaceuticals Inc. Amended and Restated 2013 Incentive Plan and the Keryx Biopharmaceuticals, Inc. 2018 Equity Incentive Plan.

(2) Shares are no longer being issued under these plans.

Common Stock Options and SARs

During the six months ended June 30, 2023, the Company issued 2,564,500 options to employees under the 2014 Plan and 315,000 options to directors under the 2023 Plan. During the six months ended June 30, 2023, the Company issued 635,313 SARs to one executive under the 2014 Plan. In addition, the Company issues stock options to directors, new hires and occasionally to other employees not in connection with the annual grant process. Options and SARs granted by the Company generally vest over periods of between 12 and 48 months, subject, in each case, to the individual’s continued service through the applicable vesting date. Options and SARs generally vest either 100% on the first anniversary of the grant date or in installments of (i) 25% at the one year anniversary and (ii) 12 equal quarterly installments beginning after the one year anniversary of the grant date, subject to the individual’s continuous service with the Company. Options and SARs generally expire 10 years after the date of grant.

The Company also maintains an inducement award program that is separate from the Company's equity plans under which inducement awards may be granted consistent with Nasdaq Listing Rule 5635(c)(4). During the six months ended June 30, 2023, the Company granted 75,000 options to purchase shares of the Company’s common stock to new hires as inducements material to such employees' entering into employment with the Company, of which 72,000 options remained outstanding as of June 30, 2023.

The Company grants annual service-based stock options to employees and directors and SARs to certain executives under the 2023 and 2014 Plans. In addition, the Company issues stock options to directors, new hires and occasionally to other employees not in connection with the annual grant process. During the six months ended June 30, 2023, the Company granted options not

in connection with the annual grant process with an aggregate grant date fair values of $0.1 million calculated using the Black-Scholes option-pricing model.

The fair value of stock options that vested during the six months ended June 30, 2023 was $4.1 million.

The combined stock option activity for the six months ended June 30, 2023, is as follows:


	Stock Options	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022	11,775,411	$	5.82	7.26 years	—
Granted	3,514,813	$	0.69	—	—
Exercised	—	—		—	—
Canceled and forfeited	(1,130,737)	$	6.35	—	—
Outstanding at June 30, 2023	14,153,498	$	4.50	7.33 years	$	1,435,662
Exercisable at June 30, 2023	7,800,000	$	6.64	6.01 years

Performance Awards

The performance-based stock options granted by the Company generally vest in connection with the achievement of specified commercial, regulatory and corporate milestones. The performance-based stock options also generally feature a time-based vesting component. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of options granted and recognized over time based on the probability of meeting such commercial, regulatory and corporate milestones.

The Company also grants performance-based restricted stock units (PSUs) to employees under the 2023 Plan and the 2014 Plan. The PSUs granted by the Company generally vest in connection with the achievement of specified commercial, regulatory and corporate milestones. The PSUs also generally feature a time-based vesting component. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of units granted and recognized over time based on the probability of meeting such commercial, regulatory and corporate milestones. The Company did not issue any performance-based stock options under the 2023 Plan or the 2014 Plan during the six months ended June 30, 2023.

Restricted Stock Units

Generally, restricted stock units (RSUs) granted by the Company vest in one of the following ways: (i) 100% of each RSU grant vests on the first anniversary of the grant date, (ii) one third of each RSU grant vests on the first, second and third anniversaries of the grant date, (iii) 50% of each RSU grant vests on the first anniversary and 25% of each RSU grant vests every six months after the one year anniversary of the grant date, or (iv) one third of each RSU grant vests on the first anniversary and the remaining two thirds vests in eight substantially equal quarterly installments beginning after the one year anniversary, subject, in each case, to the individual’s continued service through the applicable vesting date. The grant-date fair value of the RSUs is recognized as expense on a straight-line basis. The Company determines the fair value of the RSUs based on the closing price of the common stock on the date of the grants.

RSU activity is as follows:


	2014 Plan			2023 Plan
	Number of Shares	Weighted Average Fair Value		Number of Shares	Weighted Average Fair Value
Outstanding as of December 31, 2022	5,674,406	$	2.10	—	—
Granted	2,759,675	$	0.68	210,000	$	1.20
Forfeited and canceled	(564,606)	$	1.00	—	—
Outstanding as of June 30, 2023	7,869,475	$	1.30	210,000	$	1.20

As of June 30, 2023, there was $4.4 million of unrecognized compensation costs related to time-based RSUs which is expected to be recognized over a weighted-average period of 1.77 years.

Employee Stock Purchase Plan

On June 6, 2019, the Company's stockholders approved the Amended and Restated 2014 Employee Stock Purchase Plan (ESPP). Under the ESPP substantially all employees may voluntarily enroll to purchase shares of the Company’s common stock through payroll deductions at a price equal to 85% of the lower of the fair market values of the stock as of the beginning or the end of the six-month offering period. An employee's payroll deductions under the ESPP are limited to 15% of the employee's compensation, and an employee may not purchase more than $25,000 worth of stock during any calendar year. In addition, an employee may not purchase more than 1,500 shares in any offering period. As of June 30, 2023, a total of 4,734,495 shares of the Company’s common stock are available for future issuance under the ESPP. The Company issued 103,500 shares under the ESPP during the six months ended June 30, 2023.

Stock-Based Compensation Expense

The Black-Scholes option pricing model is used to estimate the fair value of the stock options. The weighted-average assumptions used in calculating the fair values the rights to acquire stock under the 2023 Plan and the 2014 Plan were as follows:


	Three Months Ended June 30,								Six Months Ended June 30,
Stock Options	2023				2022				2023				2022
Risk-free interest rate	3.67	%	-	3.99%	2.80	%	-	3.01%	3.54	%	-	3.99%	1.69	%	-	3.01%
Expected volatility	102.31	%	-	111.71%	87.99	%	-	91.57%	100.97	%	-	111.71%	79.77	%	-	91.57%
Expected term (years)	5.51 years		-	6.25 years	5.51 years		-	6.25 years	5.51 years		-	6.25 years	5.51 years		-	6.25 years
Expected dividend yield	—%				—%				—%				—%
Fair value at grant date	$0.97				$0.31				$0.56				$1.21

The Company has classified stock-based compensation in its condensed consolidated statement of operations and comprehensive income (loss) and comprehensive loss as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Research and development	$	605	$	905	$	1,341	$	2,094
Selling, general and administrative	2,685		2,709		4,220		6,056
Restructuring	$	200	$	3,303	$	418	$	3,303
Total stock-based compensation	$	3,490	$	6,917	$	5,979	$	11,453

LICENSE, COLLABORATION AND OTHER REVENUE - Medice License Agreement (Details) $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	May 24, 2023 USD ($) performance_obligation	Jun. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Disaggregation of Revenue [Line Items]
Other long-term assets		$ 3,348	$ 3,348		$ 3,348		$ 5,372
Revenue recognized			0	$ 15,503	0	$ 22,105
MEDICE Arzneimittel Pütter GmbH & Co. KG \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Disaggregation of Revenue [Line Items]
Percentage of net product margin on sales in collaborative arrangement	70.00%
License \| MEDICE Arzneimittel Pütter GmbH & Co. KG
Disaggregation of Revenue [Line Items]
Upfront payment	$ 10,000
Eligible milestone payments (up to)	$ 100,000
Tiered royalties, expected timing of satisfaction period	12 years
Termination of agreement by counterparty, written notice period	12 months
Termination of agreement eligible by counterparty, period after effective agreement date	12 months
Number of performance obligations \| performance_obligation	1
Proceeds from customers		8,600
Other long-term assets		$ 1,400	1,400		1,400
Revenue recognized			$ 10,000		$ 10,000
License \| MEDICE Arzneimittel Pütter GmbH & Co. KG \| Minimum
Disaggregation of Revenue [Line Items]
Tiered royalties	10.00%
License \| MEDICE Arzneimittel Pütter GmbH & Co. KG \| Maximum
Disaggregation of Revenue [Line Items]
Tiered royalties	30.00%

COMMITMENTS AND CONTINGENCIES - Additional Information (Details)				1 Months Ended						3 Months Ended				6 Months Ended
	Feb. 10, 2021	Apr. 02, 2020	Jan. 01, 2017 USD ($)	May 31, 2023 USD ($)	Feb. 28, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020	Feb. 28, 2019 USD ($)	Jul. 31, 2016 USD ($) ft²	Jun. 30, 2023 USD ($) ft² extension_option	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) quarter_period	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) ft² extension_option	Jun. 30, 2022 USD ($)	Nov. 30, 2020 ft²	Apr. 30, 2018 ft²
Commitments And Contingencies [Line Items]
Operating lease, cost										$ 1,400,000			$ 1,800,000	$ 3,200,000	$ 3,600,000
Operating lease, payments										1,400,000			1,800,000	3,100,000	3,700,000
Loss on lease termination										$ 524,000			0	$ 524,000	0
Operating lease, remaining lease term										3 years 2 months 12 days				3 years 2 months 12 days
Contract cost incurred in research and development activities														$ 54,900,000
Supply Agreement, Patheon Inc.
Commitments And Contingencies [Line Items]
Purchase commitment, renewal term														1 year
Purchase commitment, option for non-auto renewal, prior written notice period														18 months
Minimum purchase commitment										$ 1,900,000				$ 1,900,000
Siegfried Evionnaz SA
Commitments And Contingencies [Line Items]
Purchase commitment, option to extend, prior notice period														12 months
Cost of purchased minimum quantity product										20,800,000				$ 20,800,000
STA Pharmaceutical Hong Kong Limited
Commitments And Contingencies [Line Items]
Minimum purchase commitment, initial term		4 years
Long-term minimum purchase commitment														15,300,000
WuXi STA
Commitments And Contingencies [Line Items]
Purchase commitment, option to extend, prior notice period	18 months
Minimum purchase commitment, initial term	4 years
Long-term purchase commitment, fixed price, period	12 months
Long-term purchase commitment, option to terminate, prior notice period (at least)	180 days
BioVectra Inc
Commitments And Contingencies [Line Items]
Long-term purchase commitment, termination amount payable												$ 32,500,000
Long-term purchase commitment, upfront payment termination amount											$ 17,500,000
Long-term purchase commitment, termination amount payable after upfront payment, number of quarterly periods \| quarter_period												6
Long-term purchase commitment, termination amount payable after upfront payment, per quarter												$ 2,500,000
Long-term purchase commitment, termination amount payable after upfront payment												$ 15,000,000
Long-term purchase commitment, imputed interest on termination amount payable												17.00%
Long-term purchase commitment, upfront termination amount classified as cost of goods sold												$ 11,200,000
Amortization discount										$ 500,000				$ 900,000
Minimum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term										6.65%				6.65%
Maximum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term										6.94%				6.94%
Cambridge
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) \| ft²									45,362							65,167
Annual lease expense									$ 200,000
Monthly lease expense			$ 22,000
Cambridge \| Letter of Credit \| Other Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease										$ 1,700,000				$ 1,700,000
Cambridge \| Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) \| ft²																	19,805
Monthly lease expense						$ 48,000		$ 100,000
Operating lease, free monthly rent, period							2 months
Lease period, number of extension options \| extension_option										1				1
Lease extension period										5 years				5 years
Boston \| Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) \| ft²										27,924				27,924
Monthly lease expense					$ 200,000
Operating lease, free monthly rent, period					5 months
Operating lease, annual rent escalation, percentage					2.00%
Payments to transfer rights and obligations of operating lease				$ 1,300,000
Proceeds from return of security deposit in connection with lease														$ 1,000,000
Boston \| Office Space \| Keryx Biopharmaceuticals, Inc.
Commitments And Contingencies [Line Items]
Sublease rental income													$ 400,000	$ 300,000	$ 900,000

LIABILITY RELATED TO SALE OF FUTURE ROYALTIES - Rollforward of Liability Related to Sale of Future Royalties (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($)
Contractual Arrangement, Royalties Agreement, Liability, Noncurrent [Roll Forward]
Liability related to sale of future royalties, beginning balance at December 31, 2022	$ 57,484
MTPC royalties payable	(936)
Liability related to sale of future royalties, ending balance at June 30, 2023	$ 56,548

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2023	Mar. 31, 2022	Dec. 12, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill	$ 59,044	$ 59,044	$ 59,044	$ 59,044	$ 59,044			$ 59,044	$ 59,044
Total revenues	56,376	126,365	96,381	187,988
Accounts receivable, net	$ 19,572	82,002	$ 19,572	82,002	40,284			18,731	65,358
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Goodwill		3,991		3,991				3,991	3,991	$ 2,600
Total understatement of product return reserves and other product revenue allowances					8,183	$ 7,917	$ 6,004
Total revenues					100	1,900	600
Accounts receivable, net		$ 133		$ 133	1,100	700	700	$ 950	$ 776
Increase of goodwill					$ 1,400	$ 1,400	$ 1,400

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

- Definition

+ References

+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

LIABILITY RELATED TO SALE OF FUTURE ROYALTIES

6 Months Ended

Jun. 30, 2023

Other Liabilities Disclosure [Abstract]

On February 25, 2021, the Company entered into the Royalty Agreement with HCR, pursuant to which the Company sold to HCR its right to receive royalties and sales milestones for vadadustat in Japan and certain other Asian countries, such countries collectively, the MTPC Territory, and such payments collectively the Royalty Interest Payments, in each case, payable to the Company under the MTPC Agreement, subject to an annual maximum “cap” of $13.0 million (Annual Cap) and an aggregate maximum “cap” of $150.0 million (Aggregate Cap). The Company received $44.8 million from HCR (net of certain transaction expenses) under the Royalty Agreement. The Company retains the right to receive all potential future regulatory milestones for vadadustat under the MTPC Agreement. Although the Company sold its right to receive royalties and sales milestones for vadadustat in the MTPC Territory as described above, as a result of its ongoing involvement in the cash flows related to these royalties, the Company will continue to account for these royalties as revenue. The Company recognized the proceeds received from HCR as a liability that is being amortized using the effective interest method over the life of the arrangement. At the transaction date, the Company recorded the net proceeds of $44.8 million as a liability. In order to determine the amortization of the liability, the Company is required to estimate the total amount of future net royalty payments to be made to HCR over the term of the Royalty Agreement. The total threshold of net royalties to be paid, less the net proceeds received, will be recorded as interest expense over the life of the liability. The Company imputes interest on the unamortized portion of the liability using the effective interest method. The annual effective interest rate as of June 30, 2023 was 0% which is reflected as interest expense in the unaudited condensed consolidated statements of operations and comprehensive loss. On a quarterly basis, the Company reassesses the effective interest rate and adjusts the rate prospectively as needed. A more detailed description of Royalty Agreement can be found in Note 7 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A.

The following table shows the activity within the liability account for the six months ended June 30, 2023 (in thousands):


Liability related to sale of future royalties, beginning balance at December 31, 2022	$	57,484
MTPC royalties payable	(936)
Liability related to sale of future royalties, ending balance at June 30, 2023	$	56,548

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues
Total revenues	$ 56,376	$ 126,365	$ 96,381	$ 187,988
Cost of goods sold
Product	8,273	9,589	19,452	32,694
Amortization of intangible asset	9,011	9,011	18,021	18,021
Total cost of goods sold	17,284	18,600	37,473	50,715
Operating expenses:
Research and development	20,197	26,027	39,883	69,860
Selling, general and administrative	27,036	32,240	52,090	76,806
License expense	949	892	1,517	1,580
Restructuring	(94)	14,531	12	14,531
Total operating expenses	48,088	73,690	93,502	162,777
Operating (loss) income	(8,996)	34,075	(34,594)	(25,504)
Other income (expense)
Interest expense	(1,642)	(5,037)	(3,204)	(10,099)
Other (expense) income	(10)	411	272	1,545
Net (loss) income, basic	(11,172)	29,449	(38,050)	(34,058)
Net (loss) income, diluted	(11,172)	29,449	(38,050)	(34,058)
Comprehensive (loss) income	(11,172)	29,449	(38,050)	(34,058)
Loss on lease termination	$ (524)	$ 0	$ (524)	$ 0
Net (loss) income per share:
Basic (in dollars per share)	$ (0.06)	$ 0.16	$ (0.20)	$ (0.19)
Diluted (in dollars per share)	$ (0.06)	$ 0.15	$ (0.20)	$ (0.19)
Weighted Average Number Of Shares Outstanding, Basic And Diluted [Abstract]
Basic (in shares)	186,817,431	183,597,766	185,798,865	181,609,452
Diluted (in shares)	186,817,431	190,375,317	185,798,865	181,609,452
Product revenue, net
Revenues
Total revenues	$ 42,244	$ 43,309	$ 76,950	$ 84,681
License, collaboration and other revenue
Revenues
Total revenues	$ 14,132	$ 83,056	$ 19,431	$ 103,307

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS - Understatement of the Product Return Reserves (Details) - Adjustment - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Product return reserves and other product revenue allowances	$ 5,051	$ 4,557	$ 1,956
Product return reserves	3,132	3,360	4,048
Total understatement of product return reserves and other product revenue allowances	$ 8,183	$ 7,917	$ 6,004

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Jun. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Principals of Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (GAAP) for interim financial reporting and as required by Regulation S-X, Rule 10-01. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the ASC and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB).
Consolidation	The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, revenue and expenses, and the disclosure of contingent assets and liabilities as of and during the reported period. Management bases its estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. In certain circumstances, management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to: prepaid and accrued research and development expense, right-of-use assets and liabilities, embedded debt derivative, refund liabilities to customers, other long-term liabilities, stock-based compensation expense, and certain judgments regarding product and collaboration revenues including various rebates, returns and reserves related to product sales, non-cash interest expense on the liability related to sale of future royalties, inventories, income taxes, intangible asset and goodwill. Although the Company regularly assesses these estimates, actual results could differ materially from these estimates. Changes in estimates are recorded in the period they become known.
Cash, Cash Equivalents and Restricted Cash	he Company considers only those highly liquid investments, readily convertible to cash which as of June 30, 2023 primarily included funds invested in money market funds.

LICENSE, COLLABORATION AND OTHER REVENUE - Revenue Recognized Resulting from Changes in Contract Assets and Liabilities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue Recognized in the Period:
Deferred revenue — beginning of the period	$ 0	$ 15,503,000	$ 0	$ 22,105,000
Revenue recognized from performance obligations satisfied in previous periods	$ 0	$ 0	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)	6 Months Ended
	Jun. 30, 2023 segment
Accounting Policies [Abstract]
Number of operating segments	1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 53,572	$ 90,466
Restricted cash included in other long-term assets	1,722	2,703
Total cash, cash equivalents and restricted cash	$ 55,294	$ 93,169	$ 146,981	$ 151,839

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Assets Measured or Disclosed at Fair Value on Recurring Basis

The tables below present certain assets and liabilities measured at fair value categorized by the level of input used in the valuation of each asset and liability (in thousands):


	June 30, 2023
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	17,929	$	—	$	—	$	17,929

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760


	December 31, 2022
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	52,442	$	—	$	—	$	52,442

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760

Fair Value Derivative Liability

The tables below present certain assets and liabilities measured at fair value categorized by the level of input used in the valuation of each asset and liability (in thousands):


	June 30, 2023
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	17,929	$	—	$	—	$	17,929

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760


	December 31, 2022
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	52,442	$	—	$	—	$	52,442

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760

INVENTORIES - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Inventory Disclosure [Abstract]
Write-down of inventory	$ 300	$ 2,100	$ 612	$ 7,430
Prepaid manufacturing costs	$ 15,600		$ 15,600		$ 15,600

PRODUCT REVENUE AND RESERVES FOR VARIABLE CONSIDERATION (Tables)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Product Revenue Allowance and Reserve Categories

Product revenue allowance and reserve categories were as follows:


(in thousands)	Chargebacks and Discounts		Rebates, Fees and other Deductions		Product Returns		Total
Balance at December 31, 2022	$	1,259	$	30,043	$	10,923	$	42,225
Current provisions related to sales in current year	5,216		37,270		2,462		44,948
Adjustments related to prior year sales	(8)		(473)		—		(481)
Credits/payments made	(5,616)		(41,474)		(5,510)		(52,600)
Balance at June 30, 2023	$	851	$	25,366	$	7,875	$	34,092

(in thousands)	Chargebacks and Discounts		Rebates, Fees and other Deductions		Product Returns		Total
Balance at December 31, 2021	$	1,047	$	27,100	$	10,065	$	38,212
Current provisions related to sales in current year	4,965		42,562		2,735		50,262
Adjustments related to prior year sales	131		784		—		915
Credits/payments made	(5,236)		(43,803)		(2,968)		(52,007)
Balance at June 30, 2022	$	907	$	26,643	$	9,832	$	37,382

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN (Tables)

6 Months Ended

Jun. 30, 2023

Equity [Abstract]

Equity Plans

The following table contains information about our equity plans:

June 30, 2023

Title of Plan

Group Eligible

Type of Award Granted (or to be Granted)

Awards Outstanding

Additional Awards Authorized for Grant

Keryx Equity Plans(1)(2)*

Employees, directors and consultants

Stock options and RSUs

287,100

—

Akebia Therapeutics, Inc. Amended and Restated 2008 Equity Incentive Plan (the 2008 Plan)(2)

Employees, directors and consultants

Stock options and RSUs

419

—

Akebia Therapeutics, Inc. 2014 Incentive Plan, as amended (2)

(the 2014 Plan)

(replaces 2008 Plan)

Employees, directors, consultants and advisors

Stock options, RSUs, SARs and performance awards

17,513,530

—

Akebia Therapeutics, Inc. 2023 Stock Incentive Plan (the 2023 Plan)

(replaces 2014 Plan)

Employees, officers, directors, consultants and advisors

Stock options, SARs, restricted stock, unrestricted stock, RSUs, performance awards, other share-based awards and dividend equivalents

549,000

16,256,679

(2) Shares are no longer being issued under these plans.

Stock Option Activity

The combined stock option activity for the six months ended June 30, 2023, is as follows:


	Stock Options	Weighted Average Exercise Price		Weighted-Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022	11,775,411	$	5.82	7.26 years	—
Granted	3,514,813	$	0.69	—	—
Exercised	—	—		—	—
Canceled and forfeited	(1,130,737)	$	6.35	—	—
Outstanding at June 30, 2023	14,153,498	$	4.50	7.33 years	$	1,435,662
Exercisable at June 30, 2023	7,800,000	$	6.64	6.01 years

Restricted Stock Units Activity

RSU activity is as follows:


	2014 Plan			2023 Plan
	Number of Shares	Weighted Average Fair Value		Number of Shares	Weighted Average Fair Value
Outstanding as of December 31, 2022	5,674,406	$	2.10	—	—
Granted	2,759,675	$	0.68	210,000	$	1.20
Forfeited and canceled	(564,606)	$	1.00	—	—
Outstanding as of June 30, 2023	7,869,475	$	1.30	210,000	$	1.20

Assumptions Used in Black-Scholes Option Pricing Model

The weighted-average assumptions used in calculating the fair values the rights to acquire stock under the 2023 Plan and the 2014 Plan were as follows:


	Three Months Ended June 30,								Six Months Ended June 30,
Stock Options	2023				2022				2023				2022
Risk-free interest rate	3.67	%	-	3.99%	2.80	%	-	3.01%	3.54	%	-	3.99%	1.69	%	-	3.01%
Expected volatility	102.31	%	-	111.71%	87.99	%	-	91.57%	100.97	%	-	111.71%	79.77	%	-	91.57%
Expected term (years)	5.51 years		-	6.25 years	5.51 years		-	6.25 years	5.51 years		-	6.25 years	5.51 years		-	6.25 years
Expected dividend yield	—%				—%				—%				—%
Fair value at grant date	$0.97				$0.31				$0.56				$1.21

Stock-Based Compensation Expense in Consolidated Statement of Operations and Comprehensive Loss

The Company has classified stock-based compensation in its condensed consolidated statement of operations and comprehensive income (loss) and comprehensive loss as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Research and development	$	605	$	905	$	1,341	$	2,094
Selling, general and administrative	2,685		2,709		4,220		6,056
Restructuring	$	200	$	3,303	$	418	$	3,303
Total stock-based compensation	$	3,490	$	6,917	$	5,979	$	11,453

COMMITMENTS AND CONTINGENCIES - Future Commitments under Non-Cancelable Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Lessee, Operating Lease, Liability, to be Paid [Abstract]
Remainder of 2023	$ 2,835
2024	5,740
2025	5,818
2026	3,613
Total lease commitments	18,006
Less: present value adjustment	(1,769)
Current and long-term operating lease liabilities	$ 16,237
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other current liabilities	Accrued expenses and other current liabilities

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 53,572	$ 90,466
Inventories	20,905	21,568
Accounts receivable, net	19,572	40,284
Prepaid expenses and other current assets	24,398	32,864
Total current assets	118,447	185,182
Property and equipment, net	4,419	5,214
Operating right-of-use assets	14,391	29,158
Intangible asset, net	54,063	72,084
Goodwill	59,044	59,044
Other long-term assets	3,348	5,372
Total assets	253,712	356,054
Current liabilities:
Accounts payable	11,776	18,021
Accrued expenses and other current liabilities	56,408	75,777
Short-term deferred revenue	0	3,738
Current portion of long-term debt	24,000	32,000
Total current liabilities	92,184	129,536
Deferred revenue, net of current portion	43,296	43,296
Long-term operating lease liabilities	11,480	28,961
Embedded debt derivative	760	760
Long-term debt, net	18,486	34,078
Liability related to sale of future royalties	56,548	57,484
Refund liability to customer	40,623	40,992
Other long-term liabilities	17,142	15,717
Total liabilities	280,519	350,824
Commitments and contingencies (Note 13)
Stockholders' (deficit) equity:
Preferred stock $0.00001 par value, 25,000,000 shares authorized; no shares issued and outstanding at June 30, 2023 and December 31, 2022	0	0
Common stock $0.00001 par value; 350,000,000 shares authorized at June 30, 2023 and December 31, 2022; 188,128,869 and 184,135,714 shares issued and outstanding at June 30, 2023 and December 31, 2022, respectively	2	2
Additional paid-in capital	1,568,260	1,562,247
Accumulated other comprehensive income	6	6
Accumulated deficit	(1,595,075)	(1,557,025)
Total stockholders' (deficit) equity	(26,807)	5,230
Total liabilities and stockholders' (deficit) equity	$ 253,712	$ 356,054

FAIR VALUE OF FINANCIAL INSTRUMENTS

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

FAIR VALUE OF FINANCIAL INSTRUMENTS

The tables below present certain assets and liabilities measured at fair value categorized by the level of input used in the valuation of each asset and liability (in thousands):


	June 30, 2023
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	17,929	$	—	$	—	$	17,929

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760


	December 31, 2022
	Level 1		Level 2		Level 3		Total Fair Value
Cash equivalents:
Money market funds	$	52,442	$	—	$	—	$	52,442

Long-term liability:
Embedded debt derivative	$	—	$	—	$	760	$	760

Cash and cash equivalents —Money market funds included within cash and cash equivalents are classified within Level 1 of the fair value hierarchy because they are valued using quoted market prices in active markets.

Embedded debt derivative —As described in Note 11, the Company’s Loan Agreement with Pharmakon contains certain provisions that change the underlying cash flows of the debt instrument, including a potential extension to the interest-only period dependent on both (i) no event of default having occurred and continuing and (ii) the Company achieving certain regulatory and revenue conditions. The Company did not meet one of the regulatory conditions and therefore, the Company is no longer eligible for the interest-only extension period and this no longer changes the underlying cash flows of the debt instrument.

The Company concluded the acceleration of the obligations under the Loan Agreement under certain events of default, and under certain circumstances, the application of a default interest rate on all outstanding obligations during the occurrence and continuance of an event of default represent a single compound embedded debt derivative required to be bifurcated from the debt host instrument that is required to be re-measured at fair value on a quarterly basis.

The estimated fair value of the embedded debt derivative on both June 30, 2023 and December 31, 2022 was determined using a scenario-based approach and discounted cash flow model that includes principal and interest payments under various cash flow assumptions. Should the Company’s assessment of the probabilities around these scenarios change, including for changes in market conditions, there could be a change to the fair value of the embedded debt derivative. The determination of the fair value of the embedded debt derivative includes inputs not observable in the market and as such, represents Level 3 measurement. The methodology utilized requires inputs based on certain subjective assumptions, specifically, probabilities of acceleration of the obligations under the Loan Agreement by Pharmakon under certain events of default. The probabilities used in the valuation of the embedded debt derivative included a 95% probability that the obligations under the Loan Agreement will not be accelerated due to an event of default under the Loan Agreement.

The fair value of the embedded debt derivative related to the Company’s Loan Agreement with Pharmakon was $0.8 million as of June 30, 2023 and December 31, 2022.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

LICENSE, COLLABORATION AND OTHER REVENUE - CSL Vifor License Agreement (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 22, 2022 USD ($) shares	Feb. 18, 2022 USD ($)	Apr. 08, 2019 USD ($)	May 31, 2017 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) performance_obligation shares	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) shares	May 12, 2017 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock, issued (in shares) \| shares					188,128,869		188,128,869		184,135,714
Deferred revenue, net of current portion					$ 43,296		$ 43,296		$ 43,296
Refund liability to customer, amortization of discount					900	$ 1,100	1,700	$ 1,100
Refund liability to customer, amortization of deferred gain					1,000	$ 800	2,000	$ 800
Vifor (International) Ltd.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract termination, prior written notice period		30 months
Private Placement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares sold in offering (in shares) \| shares	4,000,000
Aggregate net proceeds from offering	$ 20,000
Aggregate net proceeds from offering, fair value in excess of carrying amount	$ 13,600
Vifor (International) Ltd.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract termination, prior written notice period		6 months
Refund liability to customer, gross					40,000		40,000
Refund liability to customer, net of deferred gain and discount					$ 40,600		$ 40,600
Vifor (International) Ltd. \| License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue, remaining performance obligation, profit share percentage		66.00%
Upfront payment		$ 25,000
Number of performance obligations \| performance_obligation							1
Refund liability to customer, purchase orders to total					50.00%		50.00%
Refund liability to customer, interest rate					15.00%		15.00%
Vifor (International) Ltd. \| License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone revenue			$ 25,000
Common stock, issued (in shares) \| shares				3,571,429
Sale of stock, price per share (in dollars per share) \| $ / shares				$ 14.00
Proceeds from common stock sold				$ 50,000
Premium over the closing stock price of common stock (in dollars per share) \| $ / shares				$ 12.69
Premium amount over the closing stock price of common stock				$ 4,700						$ 4,700
CSL Vifor
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue, net of current portion					$ 43,300		$ 43,300

LICENSE, COLLABORATION AND OTHER REVENUE - International Collaboration and License Agreement with Otsuka Pharmaceutical Co. Ltd. (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 56,376	$ 126,365	$ 96,381	$ 187,988
License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	14,132	83,056	19,431	103,307
Otsuka Pharmaceutical Company. Ltd. \| Otsuka International Agreement \| License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 0	$ 0	$ 0	$ 5,503

- Definition

+ References

+ Details

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022
Payables and Accruals [Abstract]
Product revenue allowances	$ 23,303		$ 26,268
Product return reserves, current portion	4,626		7,789
Clinical trial costs	754		5,755
Compensation and related benefits	6,582		11,481
Operating lease liabilities, current portion	$ 4,757		$ 4,744
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total accrued expenses and other current liabilities		Total accrued expenses and other current liabilities
Royalties	$ 3,198		$ 3,804
Professional fees	2,800		1,886
Accrued manufacturing costs	5,578		4,310
Restructuring costs	334		2,751
Other	4,476		6,989
Total accrued expenses and other current liabilities	$ 56,408	$ 51,079	$ 75,777	$ 95,005	$ 114,243

NET LOSS PER SHARE

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

NET LOSS PER SHARE

Potentially dilutive securities, common stock options, RSUs and SARs have been excluded from the calculation of diluted net loss per share as their effects would be anti-dilutive. For periods in which the Company reports a net loss, the weighted average number of shares outstanding used to calculate both basic and diluted net loss per share were the same except for the three months ended June 30, 2022, as the Company had net income for that period. The shares in the table below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, due to their anti-dilutive effect:


	Three Months Ended June 30,		Six Months Ended June 30,
	2023	2022	2023	2022
Outstanding common stock options and SARs	13,753,498	13,502,015	13,753,498	13,508,217
Unvested RSUs	4,596,551	—	4,596,551	6,771,349
Total	18,350,049	13,502,015	18,350,049	20,279,566

INVENTORIES - Components of Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022
Inventory Disclosure [Abstract]
Work-in-process	$ 8,571		$ 7,892
Finished goods	12,334		13,676
Inventories, current	20,905	$ 20,410	21,568	$ 40,226	$ 41,098
Raw materials included in other long-term assets	229		610
Total inventories	$ 21,134		$ 22,178

LICENSE, COLLABORATION AND OTHER REVENUE - Revenues Recognized From License, Collaboration and Other Significant Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
License, collaboration and other revenue:
Total revenues	$ 56,376	$ 126,365	$ 96,381	$ 187,988
Mitsubishi Tanabe Pharma Corporation
License, collaboration and other revenue:
Total revenues			4,000
License, collaboration and other revenue
License, collaboration and other revenue:
Total revenues	14,132	83,056	19,431	103,307
License, collaboration and other revenue \| Mitsubishi Tanabe Pharma Corporation
License, collaboration and other revenue:
Total revenues	516	434	4,678	8,398
License, collaboration and other revenue \| Otsuka Pharmaceutical Company. Ltd. \| Otsuka U.S. Agreement
License, collaboration and other revenue:
Total revenues	2,225	81,135	2,225	86,773
License, collaboration and other revenue \| Otsuka Pharmaceutical Company. Ltd. \| Otsuka International Agreement
License, collaboration and other revenue:
Total revenues	0	0	0	5,503
License, collaboration and other revenue \| Total collaboration revenue
License, collaboration and other revenue:
Total revenues	2,741	81,569	6,903	100,674
License, collaboration and other revenue \| JT and Torii Sublicense Agreement
License, collaboration and other revenue:
Total revenues	1,391	1,487	2,528	2,633
License, collaboration and other revenue \| Medice License Agreement
License, collaboration and other revenue:
Total revenues	$ 10,000	$ 0	$ 10,000	$ 0

LICENSE, COLLABORATION AND OTHER REVENUE (Tables)

6 Months Ended

Jun. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Revenues Recognized from License, Collaboration and Other Significant Agreements

The Company recognized the following revenues from its license, collaboration and other revenue agreements (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
License, collaboration and other revenue:	2023		2022		2023		2022
MTPC Collaboration Agreement	$	516	$	434	$	4,678	$	8,398
Otsuka U.S. Agreement	2,225		81,135		2,225		86,773
Otsuka International Agreement	—		—		—		5,503
Total collaboration revenue	$	2,741	$	81,569	$	6,903	$	100,674
JT and Torii Sublicense Agreement	1,391		1,487		2,528		2,633
Medice License Agreement	10,000		—		10,000		—
Total license, collaboration and other revenue	$	14,132	$	83,056	$	19,431	$	103,307

Changes in Contract Assets and Liabilities

The following table presents changes in the Company’s contract assets and liabilities (in thousands):


	Six Months Ended June 30, 2023
	Balance at Beginning of Period		Additions		Deductions		Balance at End of Period
Contract assets:
Accounts receivable(1)	$	1,901	$	943	$	(2,319)	$	525
Prepaid expenses and other current assets	$	781	$	—	$	(781)	$	—
Contract liability:
Deferred revenue	$	47,034	$	—	$	(3,738)	$	43,296

	Six Months Ended June 30, 2022
	Balance at Beginning of Period		Additions		Deductions		Balance at End of Period
Contract assets:
Accounts receivable(1)	$	19,094	$	92,146	$	(54,614)	$	56,626
Prepaid expenses and other current assets	$	4,309	$	9,550	$	(4,309)	$	9,550
Contract liabilities:
Deferred revenue	$	42,380	$	65,042	$	(59,079)	$	48,343
Accounts payable	$	3,171	$	—	$	(3,171)	$	—

Revenue Recognized Resulting from Changes in Contract Assets and Contract Liabilities

The Company recognized the following revenues as a result of changes in the contract asset and contract liability balances in the respective periods (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
Revenue Recognized in the Period:	2023		2022		2023		2022
Deferred revenue — beginning of the period	$	—	$	15,503	$	—	$	22,105

PRODUCT REVENUE AND RESERVES FOR VARIABLE CONSIDERATION - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 56,376		$ 126,365		$ 96,381	$ 187,988
Product revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	42,244	$ 34,706	$ 43,309	$ 41,372	76,950	$ 84,681
Accounts receivable, net	$ 18,200				$ 18,200		$ 37,300

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

+ References

+ Details

INTANGIBLE ASSET AND GOODWILL

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSET AND GOODWILL

Intangible Asset

Intangible asset, net of accumulated amortization, prior impairments and adjustments as of June 30, 2023 and December 31, 2022 consisted of the following (in thousands):


	Three Months Ended June 30, 2023						December 31, 2022
Intangible asset:	Gross Carrying Value		Accumulated Amortization		Net Book Value		Net Book Value		Estimated Useful Life
Developed product rights for Auryxia	$	214,705	$	(160,642)	$	54,063	$	72,084	6 years

The Company recorded $9.0 million in amortization expense for each of the three month periods ended June 30, 2023 and 2022, and $18.0 million for each of the six month periods ended June 30, 2023 and 2022.

Goodwill

On December 12, 2018, in connection with the consummation of the merger (Merger) of the Company and Keryx Biopharmaceuticals, Inc. (Keryx), Keryx became a wholly owned subsidiary of the Company, and the Company recorded goodwill representing the excess of the purchase price over the fair market value, at the date of the Merger, of the assets that were not individually identified and separately recognized as net assets. As of June 30, 2023 and December 31, 2022, the Company had goodwill of $59.0 million and no accumulated impairment losses related to goodwill. The Company's assessment included events that could indicate impairment and trigger an interim impairment assessment include, but are not limited to, an adverse change in current economic or market conditions, including a significant prolonged decline in market capitalization, a significant adverse change in legal factors, unexpected adverse business conditions, and an adverse action by a regulator.

PRODUCT REVENUE AND RESERVES FOR VARIABLE CONSIDERATION - Product Revenue Allowance and Reserve Categories (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 42,225	$ 38,212
Current provisions related to sales in current year	44,948	50,262
Adjustments related to prior year sales	(481)	915
Credits/payments made	(52,600)	(52,007)
Ending balance	34,092	37,382
Chargebacks and Discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	1,259	1,047
Current provisions related to sales in current year	5,216	4,965
Adjustments related to prior year sales	(8)	131
Credits/payments made	(5,616)	(5,236)
Ending balance	851	907
Rebates, Fees and other Deductions
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	30,043	27,100
Current provisions related to sales in current year	37,270	42,562
Adjustments related to prior year sales	(473)	784
Credits/payments made	(41,474)	(43,803)
Ending balance	25,366	26,643
Product Returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	10,923	10,065
Current provisions related to sales in current year	2,462	2,735
Adjustments related to prior year sales	0	0
Credits/payments made	(5,510)	(2,968)
Ending balance	$ 7,875	$ 9,832

NET LOSS PER SHARE (Tables)

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share

The shares in the table below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, due to their anti-dilutive effect:


	Three Months Ended June 30,		Six Months Ended June 30,
	2023	2022	2023	2022
Outstanding common stock options and SARs	13,753,498	13,502,015	13,753,498	13,508,217
Unvested RSUs	4,596,551	—	4,596,551	6,771,349
Total	18,350,049	13,502,015	18,350,049	20,279,566

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS

6 Months Ended

Jun. 30, 2023

Accounting Changes and Error Corrections [Abstract]

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTSAs previously disclosed, including in the Company's Form 12b-25 filed with the SEC on August 10, 2023, in the course of preparing its financial statements for the quarter ended June 30, 2023, the Company identified certain accounting errors relating to the recording and reporting of reserves for returns of the Company’s product, Auryxia® (ferric citrate) at the time the Company acquired Keryx Biopharmaceuticals, Inc. ("Keryx") on December 12, 2018 and when calculating the product return reserves for subsequent annual and quarterly periods through March 31, 2023 (collectively, the "Product Return Reserve Errors"). This resulted in errors in the Company's consolidated financial statements previously filed by the Company with the SEC for each of the fiscal years ended December 31, 2022, 2021 and 2020. Specifically, the Company utilized an incorrect methodology to calculate, record and report the Auryxia product return reserves at the time the Company acquired Keryx on December 12, 2018, which resulted in errors in the calculation of and understatement of goodwill of $2.6 million in each of the subsequent annual periods. The Company continued to utilize the incorrect methodology to calculate, record and report the product return reserves in the consolidated financial statements it issued with respect to its fiscal years ended December 31, 2022, 2021 and 2020, which resulted in the product return reserves and other product revenue allowances being understated by $8.2 million, $7.9 million and $6.0 million as of December 31, 2022, 2021 and 2020, respectively. A breakdown of the understatement of the product return reserves between current and long-term in the consolidated balance sheet are as follows:


	December 31,
(in thousands)	2020		2021		2022
Included in accrued expenses and other current liabilities:
Product return reserves and other product revenue allowances	$	1,956	$	4,557	$	5,051
Included in other long-term liabilities:
Product return reserves	4,048		3,360		3,132
Total understatement of product return reserves and other product revenue allowances	$	6,004	$	7,917	$	8,183

Further, as a result of the Product Return Reserve Errors, revenue was overstated by $0.1 million, $1.9 million and $0.6 million, and accounts receivable was understated by $1.1 million, $0.7 million and $0.7 million for the years ended December 31, 2022, 2021 and 2020, respectively. The changes did not impact cash or ending cash balances in the Company’s consolidated balance sheets in the periods presented in this report or in previously issued annual and quarterly financial statements.

In addition to the Product Return Reserve Errors, the Company has corrected other immaterial misstatements in the revised consolidated financial statements for the years ended December 31, 2022, 2021 and 2020 and related quarterly periods, including a $1.4 million to goodwill in each of the years ended December 31, 2022, 2021 and 2020 related to an excess purchase commitment recorded in connection with the Keryx acquisition. The changes did not impact cash or ending cash balances in the Company’s consolidated balance sheets in the periods presented in this report or in previously issued annual and quarterly financial statements.

The Company assessed the materiality of the Product Return Reserve Errors, including the presentation on prior period consolidated financial statements in accordance with the SEC Staff Accounting Bulletin No. 99, Materiality, codified in ASC Topic 250, Accounting Changes and Error Corrections (ASC 250). Based on this assessment, the Company evaluated the materiality of the impacts caused by the Product Return Reserve Errors and concluded that they do not result in a material misstatement of the Company's previously issued consolidated financial statements but would materially misstate the Company’s unaudited condensed consolidated financial statements for the three and six months ended June 30, 2023. As a result, the Company determined that it was necessary to revise the consolidated financial statements it previously issued with respect to the fiscal years ended December 31, 2022, 2021 and 2020 and filed an amendment to its Annual Report on Form 10-K for the fiscal year ended December 31, 2022 with the SEC on August 28, 2023 to reflect the revisions.

The following tables reflect the impact of this revision on the Company’s condensed consolidated financial statements as of and for the three and six months ended June 30, 2022 (dollars in thousands, except per share amounts):


	June 30, 2022
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	36,272	$	3,954	$	40,226
Accounts receivable, net	81,869		133		82,002
Total current assets	304,163		4,087		308,250
Goodwill	55,053		3,991		59,044
Total assets	$	521,804	$	8,078	$	529,882
Accrued expenses and other current liabilities	$	91,284	$	3,721	$	95,005
Total current liabilities	233,680		3,721		237,401
Other non-current liabilities	66,889		7,721		74,610
Total liabilities	459,504		11,442		470,946
Accumulated deficit	(1,493,496)		(3,363)		(1,496,859)
Total liabilities and stockholders' equity	$	521,804	$	8,078	$	529,882


Condensed Consolidated Statement of Operations and Comprehensive Income	Three Months Ended June 30, 2022
	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	43,703	$	(394)	$	43,309
Selling, general and administrative	32,807		(567)		32,240
Operating income	33,902		173		34,075
Net income	$	29,276	$	173	$	29,449
Comprehensive income	$	29,276	$	173	$	29,449
Earnings per share - basic	$0.16		$	—	$0.16
Earnings per share - diluted	$0.15		$	—	$0.15


	Six Months Ended June 30, 2022
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	85,151	$	(470)	$	84,681
Cost of goods sold, product	31,923		771		32,694
Selling, general and administrative	77,134		(328)		76,806
Operating loss	(24,591)		(913)		(25,504)
Net loss and comprehensive loss	(33,145)		(913)		(34,058)
Net loss per share - basic and diluted	$(0.18)		$(0.01)		$(0.19)


	June 30, 2022
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,493,496)	$	(3,363)	$	(1,496,859)
Net income	$	29,276	$	173	$	29,449


	Six Months Ended June 30, 2022
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(33,145)	$	(913)	$	(34,058)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments	(773)		5,627		4,854
Changes in operating assets and liabilities:
Accounts receivable	(30,994)		573		(30,421)
Inventory	1,159		(5,521)		(4,362)
Other long-term assets	9,347		665		10,012
Accrued expenses and other current liabilities	(18,625)		(839)		(19,464)
Other non-current liabilities	(9,030)		408		(8,622)
Net cash used in operating activities	$	(52,280)	$	—	$	(52,280)

The following tables reflect the impact of this revision on the Company’s condensed consolidated financial statements as of and for the three months ended March 31, 2023 and 2022 (dollars in thousands, except per share amounts):


	March 31, 2023
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	20,604	$	(194)	$	20,410
Accounts receivable, net	17,781		950		18,731
Prepaid expenses and other current assets	25,381		(678)		24,703
Total current assets	120,719		79		120,798
Goodwill	55,053		3,991		59,044
Total assets	$	276,858	$	4,070	$	280,928
Accrued expenses and other current liabilities	$	46,367	$	4,712	$	51,079
Total current liabilities	82,944		4,712		87,656
Other non-current liabilities	12,643		4,129		16,772
Total liabilities	291,210		8,841		300,051
Accumulated deficit	(1,579,130)		(4,773)		(1,583,903)
Total liabilities and stockholders' equity	$	276,858	$	4,070	$	280,928


	Three Months Ended March 31, 2023
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	34,828	$	(122)	$	34,706
Cost of goods sold, product	10,473		705		11,178
Selling, general and administrative	25,221		(168)		25,053
Operating loss	(24,938)		(661)		(25,599)
Net loss	$	(26,217)	$	(661)	$	(26,878)
Comprehensive loss	$	(26,217)	$	(661)	$	(26,878)
Earnings per share - basic and diluted	$	(0.14)	$	(0.01)	$	(0.15)


	March 31, 2023
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,579,130)	$	(4,773)	$	(1,583,903)
Net loss	$	(26,217)	$	(661)	$	(26,878)


	Three Months Ended March 31, 2023
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(26,217)	$	(661)	$	(26,878)
Changes in operating assets and liabilities:
Accounts receivable	21,399		154		21,553
Accrued expenses and other current liabilities	(25,047)		(68)		(25,115)
Other non-current liabilities	—		573		573
Net cash used in operating activities	$	(17,538)	$	(2)	$	(17,540)


	March 31, 2022
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	39,422	$	1,676	$	41,098
Accounts receivable, net	64,582		776		65,358
Total current assets	302,687		2,452		305,139
Goodwill	55,053		3,991		59,044
Total assets	$	535,356	$	6,443	$	541,799
Accrued expenses and other current liabilities	$	109,660	$	4,583	$	114,243
Total current liabilities	253,914		4,583		258,497
Other non-current liabilities	77,743		5,398		83,141
Total liabilities	509,240		9,981		519,221
Accumulated deficit	(1,522,772)		(3,536)		(1,526,308)
Total liabilities and stockholders' equity	$	535,356	$	6,443	$	541,799


	Three Months Ended March 31, 2022
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	41,448	$	(76)	$	41,372
Cost of goods sold, product	22,333		772		23,105
Selling, general and administrative	44,327		239		44,566
Operating loss	(58,493)		(1,088)		(59,581)
Net loss	$	(62,421)	$	(1,088)	$	(63,509)
Comprehensive loss	$	(62,421)	$	(1,088)	$	(63,509)
Earnings per share - basic and diluted	$(0.35)		$	—	$(0.35)


	March 31, 2022
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,522,772)	$	(3,536)	$	(1,526,308)
Net loss	$	(62,421)	$	(1,088)	$	(63,509)


	Three Months Ended March 31, 2022
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(62,421)	$	(1,088)	$	(63,509)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments	(773)		773		—
Changes in operating assets and liabilities:
Accounts receivable	(13,707)		(71)		(13,778)
Inventory	(5,247)		(3,243)		(8,490)
Other long-term assets	3,297		669		3,966
Accrued expenses and other current liabilities	4,426		2,960		7,386
Net cash used in operating activities	$	(21,620)	$	—	$	(21,620)


	December 31, 2021
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,460,351)	$	(2,448)	$	(1,462,799)
Net loss	$	(282,840)	$	816	$	(282,024)

The consolidated balance sheet as of December 31, 2022 has been revised in this Quarterly Report on Form 10-Q.

SUBSEQUENT EVENTS	6 Months Ended
SUBSEQUENT EVENTS	Jun. 30, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSThe Company has completed an evaluation of all subsequent events after the balance sheet date of June 30, 2023, through the filing date of this Quarterly Report on Form 10-Q with the SEC, to ensure that the condensed consolidated financial statements include appropriate disclose of events both recognized in the consolidated financial statements as of June 30, 2023, and events which occurred subsequently but were not recognized in the consolidated financial statements. The Company has concluded that no subsequent events have occurred that require disclosure.

COMMITMENTS AND CONTINGENCIES (Tables)

6 Months Ended

Jun. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Future Commitments under Non-Cancelable Leases

Future commitments under non-cancelable lease agreements are as follows:


Years ending December 31,	Operating Lease Commitments
Remainder of 2023	$	2,835
2024	5,740
2025	5,818
2026	3,613
Total lease commitments	$	18,006
Less: present value adjustment	(1,769)
Current and long-term operating lease liabilities	$	16,237

INTANGIBLE ASSET AND GOODWILL - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 9,000,000	$ 9,000,000	$ 18,021,000	$ 18,021,000
Goodwill	59,044,000	$ 59,044,000	59,044,000	$ 59,044,000	$ 59,044,000	$ 59,044,000	$ 59,044,000
Goodwill, accumulated impairment losses	$ 0		$ 0			$ 0

- Definition

+ References + Details

COMMITMENTS AND CONTINGENCIES

6 Months Ended

Jun. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Cambridge Leases

The Company leases approximately 65,167 square feet of office and lab space in Cambridge, Massachusetts under a lease which was most recently amended in November 2020 (collectively, the Cambridge Lease). Under the Third Amendment to the Cambridge Lease (Third Amendment), executed in July 2016, total monthly lease payments under the initial base rent were approximately $0.2 million and are subject to annual rent escalations. In addition to such annual rent escalations, base rent payments for a portion of said premises commenced on January 1, 2017 in the monthly amount of approximately $22,000. The Fourth Amendment to the Cambridge Lease, executed in May 2017, provided additional storage space to the Company and did not impact rent payments. In April 2018, the Company entered into a Fifth Amendment to the Cambridge Lease (Fifth Amendment) for an additional 19,805 square feet of office space on the 12th floor. Monthly lease payments for the existing 45,362 square feet of office and lab space, under the Third Amendment, remain unchanged. The new space leased by the Company was delivered in September 2018 and additional monthly lease payments of approximately $0.1 million commenced in February 2019 and are subject to annual rent escalations, which commenced in September 2019. In November 2020, the Company entered into a Sixth Amendment to the Cambridge Lease (Sixth Amendment) to extend the term of the Cambridge Lease with respect to the lab space from November 30, 2021 to January 31, 2025. The Sixth Amendment includes two months of free rent starting in December 2020 and additional monthly lease payments of approximately $48,000, which commenced in December 2021, and is subject to annual rent escalations, which commenced in December 2022.

The term of the Cambridge Lease with respect to the office space expires on September 11, 2026, with one five-year extension option available. The renewal option in this real estate lease was not included in the calculation of the right-of-use asset and operating lease liability as the renewal is not reasonably certain. The term of the Cambridge Lease with respect to the lab space expires on January 31, 2025, with an extension option for one additional period through September 11, 2026. The renewal option in this real estate lease was included in the calculation of the right-of-use assets and operating lease liabilities as the renewal is reasonably certain. The lease agreements do not contain residual value guarantees. Operating lease costs were $1.4 million and $1.8 million for the three months ended June 30, 2023 and 2022, respectively, and $3.2 million and $3.6 million for the six months ended June 30, 2023 and 2022, respectively. Cash paid for amounts included in the measurement of operating lease liabilities was $1.4 million and $1.8 million for the three months ended June 30, 2023 and 2022, respectively, and $3.1 million and $3.7 million for the six months ended June 30, 2023 and 2022, respectively. The security deposit in connection with the Cambridge Lease is $1.7 million in the form of a letter of credit, which is included as restricted cash in prepaid expenses and other current assets in the Company’s unaudited condensed consolidated balance sheets as of June 30, 2023.

The Company has not entered into any material short-term leases or financing leases as of June 30, 2023.

Former Boston Lease

Previously, the Company leased 27,924 square feet of office space in Boston, Massachusetts (Boston Lease). In February 2022, the Company entered into the First Amendment to the Boston Lease (First Lease Amendment) to extend the term of the Boston Lease from February 2023 to July 2031. The First Lease Amendment included five months of free rent starting in March 2023 and monthly lease payments of $0.2 million commencing on August 1, 2023, with an annual rent escalation of approximately 2% commencing on August 1, 2024. In May 2023, the Company entered into an Assignment and Assumption of Lease Agreement (Lease Assignment Agreement) with LG Chem Life Sciences Innovation Center, Inc. (LG Chem), pursuant to which the Company assigned all of its rights, title, and interest in, to, and under the Boston Lease to LG Chem, or the Assignment. As part of the Lease Assignment Agreement, the Company made a payment to LG Chem of $1.3 million (Lease Assignment Amount) and LG Chem assumed all of the rights and obligations of the Company under the Boston Lease. Subsequent to the Assignment, the Company has no further obligations for rent or other payments under the Boston Lease. In accordance with ASC 842, Leases, the Company wrote off the right-of-use asset and lease liability associated with the Boston Lease, and recognized the difference between the right-of-use asset and the lease liability offset by the Assignment Amount as a loss on lease termination in the condensed consolidated statement of operations and comprehensive income (loss) of $0.5 million during the three and six months ended June 30, 2023. Under the terms of the Lease Assignment Agreement the Company was entitled to, and received back, its security deposit of $1.0 million as of June 30, 2023, which had been recorded as restricted cash in prepaid expenses and other current assets in the Company's condensed consolidated balance sheet as of December 31, 2022.

In September 2019, the Company entered into an agreement to sublease the Boston office space to Foundation Medicine, Inc.(Foundation). The sublease was subject and subordinate to the Boston Lease between the Company and the landlord. The term of the sublease commenced on October 16, 2019, upon receipt of the required consent from the landlord for the sublease

agreement, and expired on February 27, 2023. Foundation was obligated to pay the Company rent that approximated the rent due from the Company to its landlord with respect to the Boston Lease. Sublease rental income is recorded to other income in the condensed consolidated statement of operations and other comprehensive income (loss). The Company was obligated for all payment terms pursuant to the Boston Lease, and the Company guaranteed the obligations under the sublease. The Company did not record any sublease rental income for the three months ended June 30, 2023 and recorded $0.3 million in sublease rental income from Foundation during the six months ended June 30, 2023. The Company recorded sublease rental income of $0.4 million and $0.9 million during the three and six months ended June 30, 2022, respectively.

Future Lease Commitments

Future commitments under non-cancelable lease agreements are as follows:


Years ending December 31,	Operating Lease Commitments
Remainder of 2023	$	2,835
2024	5,740
2025	5,818
2026	3,613
Total lease commitments	$	18,006
Less: present value adjustment	(1,769)
Current and long-term operating lease liabilities	$	16,237

In arriving at the operating lease liabilities, the Company applied incremental borrowing rates ranging from 6.65% to 6.94%, which were based on the remaining lease term at either the date of adoption of ASC 842 or the effective date of any subsequent lease term extensions. As of June 30, 2023, the remaining lease term for the Cambridge Lease was 3.20 years.

Manufacturing and Unconditional Purchase Commitment Agreements

The Company's contractual obligations include a commercial supply agreement with Siegfried Evionnaz SA (Siegfried) to supply commercial drug substance for Auryxia.

Pursuant to the Master Manufacturing Services and Supply Agreement between the Company and Siegfried, as amended (the most recent amendment having been executed on February 28, 2023) (Siegfried Agreement), the Company has agreed to purchase a minimum quantity of drug substance of Auryxia at a predetermined price. The term of the Siegfried Agreement expires on December 31, 2024, unless otherwise agreed by the parties and subject to the Company's option to extend the term through December 31, 2026 by providing 12 months’ prior written notice to Siegfried. The Siegfried Agreement provides the Company and Siegfried with certain early termination rights. As of June 30, 2023, the Company is required to purchase a minimum quantity of drug substance for Auryxia annually at a total cost of approximately $20.8 million through the end of 2024.

On April 9, 2019, the Company and Esteve entered into the Esteve Agreement, which included the terms and conditions under which Esteve would manufacture vadadustat drug substance for commercial use. Pursuant to the Esteve Agreement, the Company provided rolling forecasts to Esteve on a quarterly basis, or the Esteve Forecast. The Esteve Forecast reflected the Company’s needs for vadadustat drug substance produced by Esteve over a certain number of months, represented as a quantity of vadadustat drug substance per calendar quarter. The parties agreed to a volume-based pricing structure under the Esteve Agreement. On December 16, 2022, the Company, MTPC, and Esteve executed the Esteve Assignment Agreement, pursuant to which the Supply Agreement between the Company and Esteve was assigned to MTPC. The Esteve Assignment Agreement transferred the rights and obligations of the Supply Agreement to MTPC, specifically including the obligations under certain purchase orders issued by the Company and accepted by Esteve. As such, the Company will have no further obligation to take delivery of or pay for product delivered by Esteve under the transferred Esteve Agreement and the purchase orders.

On March 11, 2020, the Company entered into a Supply Agreement with Patheon Inc. (Patheon) or the Patheon Agreement. The Patheon Agreement includes the terms and conditions under which Patheon will manufacture vadadustat drug product for commercial use. Pursuant to the Patheon Agreement, the Company provides Patheon a long-term forecast on an annual basis, as well as short-term forecasts on a quarterly basis, or the Patheon Forecast. The Patheon Forecast reflects the Company’s needs for commercial supply of vadadustat drug product produced by Patheon, represented as a quantity of drug product per calendar quarter. The parties have agreed to a volume-based pricing structure under the Patheon Agreement. The Patheon Agreement has an initial term beginning March 11, 2020 and ending June 30, 2023 and automatically renews for successive one-year terms unless either party gives the other party eighteen months' prior written notice. The current term of the Patheon Agreement ends

June 30, 2025. Pursuant to the Patheon Agreement, the Company has agreed to purchase a certain percentage of the global demand for vadadustat drug product from Patheon. As of June 30, 2023, the Company had a minimum commitment with Patheon for $1.9 million through the third quarter of 2023.

On April 2, 2020, the Company entered into a Supply Agreement with STA Pharmaceutical Hong Kong Limited, a subsidiary of WuXi AppTec (WuXi STA), as amended on April 15, 2021 (WuXi STA DS Agreement). The WuXi STA DS Agreement includes the terms and conditions under which WuXi STA will manufacture vadadustat drug substance for commercial use. Pursuant to the WuXi STA DS Agreement, the Company provides rolling forecasts to WuXi STA on a quarterly basis, or the WuXi STA DS Forecast. The WuXi STA DS Forecast reflects the Company’s needs for vadadustat drug substance produced by WuXi STA over a certain number of quarters. The parties have agreed to a volume-based pricing structure under the WuXi STA DS Agreement. The WuXi STA DS Agreement has an initial term of four years, beginning April 2, 2020 and ending April 2, 2024. Pursuant to the WuXi STA DS Agreement, the Company has agreed to purchase a certain percentage of the global demand for vadadustat drug substance from WuXi STA. As of June 30, 2023, the Company has committed to purchase $15.3 million of vadadustat drug substance from WuXi STA through the end of 2023.

On February 10, 2021, the Company entered into a Supply Agreement with WuXi STA, or the WuXi STA DP Agreement. The WuXi STA DP Agreement includes the terms and conditions under which WuXi STA will manufacture and supply vadadustat drug product for commercial purposes. Pursuant to the WuXi STA DP Agreement, the Company will provide rolling forecasts to WuXi STA on a quarterly basis, or the WuXi STA DP Forecast. Each WuXi STA DP Forecast will reflect the quantities of vadadustat drug product that the Company expects to order from WuXi STA over a certain number of months, represented as a quantity of vadadustat drug product per calendar quarter. Pursuant to the WuXi STA DP Agreement, the Company has agreed to purchase a certain percentage of global demand for vadadustat drug product from WuXi STA. The parties have agreed to a volume-based pricing structure under the WuXi STA DP Agreement. The vadadustat drug product price will remain fixed for the first 12 months and thereafter shall be annually reviewed by the Company and WuXi STA. The Company will also reimburse WuXi STA for certain reasonable expenses. The WuXi STA DP Agreement has an initial term of four years, beginning February 10, 2021 and ending February 10, 2025. The WuXi STA DP Agreement may be renewed or extended by mutual agreement of the Company and WuXi STA with at least 18 months’ prior written notice. The WuXi STA DP Agreement allows the Company to terminate the relationship on 180 calendar days’ prior written notice to WuXi STA for any reason. In addition, each party has the ability to terminate the WuXi STA DP Agreement upon the occurrence of certain conditions.

Former Manufacturing and Unconditional Purchase Commitments

Pursuant to the Manufacture and Supply Agreement with BioVectra and the Amended and Restated Product Manufacture and Supply and Facility Construction Agreement with BioVectra, the Company agreed to purchase minimum quantities of Auryxia drug substance annually at predetermined prices as well as reimburse BioVectra for certain costs in connection with construction of a new facility for the manufacture and supply of Auryxia drug substance.

On December 22, 2022, the Company and BioVectra entered into a termination agreement (BioVectra Termination Agreement), pursuant to which the parties agreed, among other things, to terminate, effective immediately, any and all existing agreements entered into between the parties in connection with the manufacture and supply, by BioVectra to the Company, of Auryxia drug substance. Under the terms of the BioVectra Termination Agreement, each of the Company and BioVectra have released one another from all existing and future claims and liabilities and the return of certain materials and documents. Furthermore, as it relates to all open purchase orders, BioVectra is relieved from any obligations to manufacture any product or perform services under any such open purchase orders, and the Company is relieved from any obligations to purchase any product under such open purchase orders. The Company is also relieved from any obligations to pay any outstanding invoices related to performance by BioVectra of services and all other obligations under the agreements. In addition, the Company agreed to pay BioVectra a total of $32.5 million consisting of (i) an upfront payment of $17.5 million and (ii) six quarterly payments of $2.5 million commencing in April 2024, totaling $15.0 million. The upfront payment of $17.5 million was made during the quarter ended December 31, 2022 and was recognized to cost of goods sold. In accordance with ASC 420, Exit or Disposal Cost Obligations, the Company recognized a liability and corresponding expense for the remaining termination fees based on estimated fair value as of December 22, 2022 (BioVectra Effective Date). The Company imputed interest on the liability for the remaining termination fees at a rate of 17.0% per annum, which was determined based on certain factors, including the Company's credit rating, comparable securities yield, and expected repayment period of the remaining termination fees. The Company recorded an initial discount on the remaining termination fees on the consolidated balance sheet as of the BioVectra Effective Date. This resulted in the recording of a liability and corresponding charge to cost of goods sold of $11.2 million during the quarter ended December 31, 2022. The discount on the liability balance is being amortized to interest expense using the effective interest rate method over the term of the liability. The amortization of the discount was $0.5 million and $0.9 million for the three and six months ended June 30, 2023, respectively.

Other Third-Party Contracts

The Company contracts with various organizations to conduct research and development activities with remaining contract costs to the Company of approximately $54.9 million at June 30, 2023. The scope of the services under these research and

development contracts can be modified and the contracts cancelled by the Company upon written notice. In some instances, the contracts may be cancelled by the third party upon written notice.

Litigation and Related Matters

The Company is involved from time to time in various legal proceedings arising in the normal course of business. The Company provides disclosure when a loss in excess of any reserve is reasonably possible, and if estimable, the Company discloses the potential loss or range of possible loss. Significant judgment is required to assess the likelihood of various potential outcomes and the quantification of loss in those scenarios. Changes in the Company’s estimates could have a material impact and are recorded as litigation progresses and new information comes to light. Although the outcomes of potential legal proceedings are inherently difficult to predict, the Company does not expect the resolution of these occasional legal proceedings to have a material adverse effect on its financial position, results of operations or cash flows.

Guarantees and Indemnifications

As permitted under Delaware law, the Company may indemnify its officers, directors and employees for certain events or occurrences that happen by reason of their relationship with, or position held at, the Company. The Company may also be subject to indemnification obligations by law with respect to the actions of its employees under certain circumstances and in certain jurisdictions. The Company maintains director and officer liability insurance coverage that is intended to cover a portion of amounts that may be due with respect to indemnification after a deductible is met. Further, the Company is a party to a variety of agreements in the ordinary course of business under which it may be obligated to indemnify third parties with respect to certain matters. For the three and six months ended June 30, 2023 and 2022, the Company did not experience any losses related to these indemnification obligations, and no claims were outstanding as of June 30, 2023. The Company does not have any claims related to these indemnification obligations and consequently concluded that the fair value of these obligations is negligible and no related accruals were recorded.

REVISION OF PREVIOUSLY ISSUED FINANCIAL STATEMENTS (Tables)

6 Months Ended

Jun. 30, 2023

Accounting Changes and Error Corrections [Abstract]

Error Corrections and Prior Period Adjustments

A breakdown of the understatement of the product return reserves between current and long-term in the consolidated balance sheet are as follows:


	December 31,
(in thousands)	2020		2021		2022
Included in accrued expenses and other current liabilities:
Product return reserves and other product revenue allowances	$	1,956	$	4,557	$	5,051
Included in other long-term liabilities:
Product return reserves	4,048		3,360		3,132
Total understatement of product return reserves and other product revenue allowances	$	6,004	$	7,917	$	8,183


	June 30, 2022
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	36,272	$	3,954	$	40,226
Accounts receivable, net	81,869		133		82,002
Total current assets	304,163		4,087		308,250
Goodwill	55,053		3,991		59,044
Total assets	$	521,804	$	8,078	$	529,882
Accrued expenses and other current liabilities	$	91,284	$	3,721	$	95,005
Total current liabilities	233,680		3,721		237,401
Other non-current liabilities	66,889		7,721		74,610
Total liabilities	459,504		11,442		470,946
Accumulated deficit	(1,493,496)		(3,363)		(1,496,859)
Total liabilities and stockholders' equity	$	521,804	$	8,078	$	529,882


Condensed Consolidated Statement of Operations and Comprehensive Income	Three Months Ended June 30, 2022
	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	43,703	$	(394)	$	43,309
Selling, general and administrative	32,807		(567)		32,240
Operating income	33,902		173		34,075
Net income	$	29,276	$	173	$	29,449
Comprehensive income	$	29,276	$	173	$	29,449
Earnings per share - basic	$0.16		$	—	$0.16
Earnings per share - diluted	$0.15		$	—	$0.15


	Six Months Ended June 30, 2022
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	85,151	$	(470)	$	84,681
Cost of goods sold, product	31,923		771		32,694
Selling, general and administrative	77,134		(328)		76,806
Operating loss	(24,591)		(913)		(25,504)
Net loss and comprehensive loss	(33,145)		(913)		(34,058)
Net loss per share - basic and diluted	$(0.18)		$(0.01)		$(0.19)


	June 30, 2022
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,493,496)	$	(3,363)	$	(1,496,859)
Net income	$	29,276	$	173	$	29,449


	Six Months Ended June 30, 2022
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(33,145)	$	(913)	$	(34,058)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments	(773)		5,627		4,854
Changes in operating assets and liabilities:
Accounts receivable	(30,994)		573		(30,421)
Inventory	1,159		(5,521)		(4,362)
Other long-term assets	9,347		665		10,012
Accrued expenses and other current liabilities	(18,625)		(839)		(19,464)
Other non-current liabilities	(9,030)		408		(8,622)
Net cash used in operating activities	$	(52,280)	$	—	$	(52,280)


	March 31, 2023
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	20,604	$	(194)	$	20,410
Accounts receivable, net	17,781		950		18,731
Prepaid expenses and other current assets	25,381		(678)		24,703
Total current assets	120,719		79		120,798
Goodwill	55,053		3,991		59,044
Total assets	$	276,858	$	4,070	$	280,928
Accrued expenses and other current liabilities	$	46,367	$	4,712	$	51,079
Total current liabilities	82,944		4,712		87,656
Other non-current liabilities	12,643		4,129		16,772
Total liabilities	291,210		8,841		300,051
Accumulated deficit	(1,579,130)		(4,773)		(1,583,903)
Total liabilities and stockholders' equity	$	276,858	$	4,070	$	280,928


	Three Months Ended March 31, 2023
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	34,828	$	(122)	$	34,706
Cost of goods sold, product	10,473		705		11,178
Selling, general and administrative	25,221		(168)		25,053
Operating loss	(24,938)		(661)		(25,599)
Net loss	$	(26,217)	$	(661)	$	(26,878)
Comprehensive loss	$	(26,217)	$	(661)	$	(26,878)
Earnings per share - basic and diluted	$	(0.14)	$	(0.01)	$	(0.15)


	March 31, 2023
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,579,130)	$	(4,773)	$	(1,583,903)
Net loss	$	(26,217)	$	(661)	$	(26,878)


	Three Months Ended March 31, 2023
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(26,217)	$	(661)	$	(26,878)
Changes in operating assets and liabilities:
Accounts receivable	21,399		154		21,553
Accrued expenses and other current liabilities	(25,047)		(68)		(25,115)
Other non-current liabilities	—		573		573
Net cash used in operating activities	$	(17,538)	$	(2)	$	(17,540)


	March 31, 2022
Condensed Consolidated Balance Sheet	As Previously Reported		Adjustment		As Revised
Inventories	$	39,422	$	1,676	$	41,098
Accounts receivable, net	64,582		776		65,358
Total current assets	302,687		2,452		305,139
Goodwill	55,053		3,991		59,044
Total assets	$	535,356	$	6,443	$	541,799
Accrued expenses and other current liabilities	$	109,660	$	4,583	$	114,243
Total current liabilities	253,914		4,583		258,497
Other non-current liabilities	77,743		5,398		83,141
Total liabilities	509,240		9,981		519,221
Accumulated deficit	(1,522,772)		(3,536)		(1,526,308)
Total liabilities and stockholders' equity	$	535,356	$	6,443	$	541,799


	Three Months Ended March 31, 2022
Condensed Consolidated Statement of Operations and Comprehensive Income	As Previously Reported		Adjustment		As Revised
Product revenue, net	$	41,448	$	(76)	$	41,372
Cost of goods sold, product	22,333		772		23,105
Selling, general and administrative	44,327		239		44,566
Operating loss	(58,493)		(1,088)		(59,581)
Net loss	$	(62,421)	$	(1,088)	$	(63,509)
Comprehensive loss	$	(62,421)	$	(1,088)	$	(63,509)
Earnings per share - basic and diluted	$(0.35)		$	—	$(0.35)


	March 31, 2022
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,522,772)	$	(3,536)	$	(1,526,308)
Net loss	$	(62,421)	$	(1,088)	$	(63,509)


	Three Months Ended March 31, 2022
Condensed Consolidated Statement of Cash Flows	As Previously Reported		Adjustment		As Revised
Net loss	$	(62,421)	$	(1,088)	$	(63,509)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in excess inventory purchase commitments	(773)		773		—
Changes in operating assets and liabilities:
Accounts receivable	(13,707)		(71)		(13,778)
Inventory	(5,247)		(3,243)		(8,490)
Other long-term assets	3,297		669		3,966
Accrued expenses and other current liabilities	4,426		2,960		7,386
Net cash used in operating activities	$	(21,620)	$	—	$	(21,620)


	December 31, 2021
Condensed Consolidated Statement of Stockholders' (Deficit) Equity	As Previously Reported		Adjustment		As Revised
Accumulated deficit	$	(1,460,351)	$	(2,448)	$	(1,462,799)
Net loss	$	(282,840)	$	816	$	(282,024)

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		177,000,963
Beginning balance at Dec. 31, 2021	$ 74,008	$ 1	$ 1,536,800	$ 6	$ (1,462,799)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs (in shares)		4,404,600
Issuance of common stock, net of issuance costs	7,178	$ 1	7,177
Proceeds from sale of stock under employee stock purchase plan (in shares)		191,146
Proceeds from sale of stock under employee stock purchase plan	367		367
Stock-based compensation expense	4,536		4,536
Restricted stock unit vesting (in shares)		1,789,326
Net loss	(63,509)				(63,509)
Ending balance (in shares) at Mar. 31, 2022		183,386,035
Ending balance at Mar. 31, 2022	22,580	$ 2	1,548,880	6	(1,526,308)
Beginning balance (in shares) at Dec. 31, 2021		177,000,963
Beginning balance at Dec. 31, 2021	74,008	$ 1	1,536,800	6	(1,462,799)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(34,058)
Ending balance (in shares) at Jun. 30, 2022		183,704,654
Ending balance at Jun. 30, 2022	58,937	$ 2	1,555,788	6	(1,496,859)
Beginning balance (in shares) at Mar. 31, 2022		183,386,035
Beginning balance at Mar. 31, 2022	22,580	$ 2	1,548,880	6	(1,526,308)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 6,841		6,841
Exercise of options (in shares)	142,440
Exercise of options	$ 67
Restricted stock unit vesting (in shares)		176,179
Net loss	29,449				29,449
Ending balance (in shares) at Jun. 30, 2022		183,704,654
Ending balance at Jun. 30, 2022	$ 58,937	$ 2	1,555,788	6	(1,496,859)
Beginning balance (in shares) at Dec. 31, 2022	184,135,714	184,135,714
Beginning balance at Dec. 31, 2022	$ 5,230	$ 2	1,562,247	6	(1,557,025)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from sale of stock under employee stock purchase plan (in shares)		103,500
Proceeds from sale of stock under employee stock purchase plan	34		34
Stock-based compensation expense	2,489		2,489
Restricted stock unit vesting (in shares)		1,596,732
Net loss	(26,878)				(26,878)
Ending balance (in shares) at Mar. 31, 2023		185,835,946
Ending balance at Mar. 31, 2023	$ (19,125)	$ 2	1,564,770	6	(1,583,903)
Beginning balance (in shares) at Dec. 31, 2022	184,135,714	184,135,714
Beginning balance at Dec. 31, 2022	$ 5,230	$ 2	1,562,247	6	(1,557,025)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)	0
Net loss	$ (38,050)
Ending balance (in shares) at Jun. 30, 2023	188,128,869	188,128,869
Ending balance at Jun. 30, 2023	$ (26,807)	$ 2	1,568,260	6	(1,595,075)
Beginning balance (in shares) at Mar. 31, 2023		185,835,946
Beginning balance at Mar. 31, 2023	(19,125)	$ 2	1,564,770	6	(1,583,903)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	3,490		3,490
Restricted stock unit vesting (in shares)		2,292,923
Net loss	$ (11,172)				(11,172)
Ending balance (in shares) at Jun. 30, 2023	188,128,869	188,128,869
Ending balance at Jun. 30, 2023	$ (26,807)	$ 2	$ 1,568,260	$ 6	$ (1,595,075)

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Additional Information (Details)						3 Months Ended			6 Months Ended
	Apr. 07, 2022 USD ($)	Mar. 01, 2022 USD ($)	Feb. 25, 2021 USD ($)	Mar. 12, 2020 USD ($)	Jun. 06, 2019 USD ($) shares	Jun. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2022 USD ($) shares	Jun. 30, 2023 USD ($) executive_officer installment $ / shares shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2023 shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 shares	Jun. 04, 2020 shares
Class of Stock [Line Items]
Common stock, authorized (in shares)						350,000,000			350,000,000			350,000,000		175,000,000
Common stock, par value (in dollars per share) \| $ / shares						$ 0.00001			$ 0.00001			$ 0.00001
Common stock, issued (in shares)						188,128,869			188,128,869			184,135,714
Common stock, outstanding (in shares)						188,128,869			188,128,869			184,135,714
Preferred stock, shares authorized (in shares)						25,000,000			25,000,000			25,000,000
Preferred stock, par value (in dollars per share) \| $ / shares						$ 0.00001			$ 0.00001			$ 0.00001
Preferred stock, issued (in shares)						0			0			0
Preferred stock, outstanding (in shares)						0			0			0
Proceeds from issuance of common stock, net of issuance costs \| $									$ 0	$ 7,102,000
Stock-based compensation expense \| $						$ 3,490,000	$ 6,917,000		$ 5,979,000	$ 11,453,000
Number of shares granted									3,514,813
Number of shares outstanding						14,153,498			14,153,498			11,775,411
Open Market Sale Agreement, Authorized April 2022 \| Maximum
Class of Stock [Line Items]
Common stock sales agreement amount \| $	$ 26,000,000
At The Market Equity Offering Program Authorized February 2021 \| Maximum
Class of Stock [Line Items]
Common stock sales agreement amount \| $			$ 100,000,000
At The Market Equity Offering Program Authorized March 2022 \| Maximum
Class of Stock [Line Items]
Common stock sales agreement amount \| $		$ 25,300,000
Share-based Payment Arrangement, Option
Class of Stock [Line Items]
Expiration period									10 years
Share-based Payment Arrangement, Option \| Maximum
Class of Stock [Line Items]
Vesting period									48 months
Share-based Payment Arrangement, Option \| Minimum
Class of Stock [Line Items]
Vesting period									12 months
Share-based Payment Arrangement, Option \| Share-based Compensation Award, Tranche, First Anniversary of Grant Date
Class of Stock [Line Items]
Vesting percentage									100.00%
Share-based Payment Arrangement, Option \| Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									25.00%
Share-based Payment Arrangement, Option \| Share Based Compensation Award Tranche Two
Class of Stock [Line Items]
Vesting period									1 year
Number of equal quarterly installments \| installment									12
Stock Appreciation Rights (SARs)
Class of Stock [Line Items]
Expiration period									10 years
Stock Appreciation Rights (SARs) \| Maximum
Class of Stock [Line Items]
Vesting period									48 months
Stock Appreciation Rights (SARs) \| Minimum
Class of Stock [Line Items]
Vesting period									12 months
Stock Appreciation Rights (SARs) \| Share-based Compensation Award, Tranche, First Anniversary of Grant Date
Class of Stock [Line Items]
Vesting percentage									100.00%
Stock Appreciation Rights (SARs) \| Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									25.00%
Stock Appreciation Rights (SARs) \| Share Based Compensation Award Tranche Two
Class of Stock [Line Items]
Vesting period									1 year
Number of equal quarterly installments \| installment									12
Inducement Award Program
Class of Stock [Line Items]
Number of shares granted									75,000
Number of shares outstanding						72,000			72,000
Service-Based Restricted Stock Units
Class of Stock [Line Items]
Unrecognized compensation costs \| $						$ 4,400,000			$ 4,400,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition									1 year 9 months 7 days
Service-Based Restricted Stock Units \| Share-based Compensation Award, Tranche, First Anniversary of Grant Date
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									100.00%
Service-Based Restricted Stock Units \| Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									50.00%
Service-Based Restricted Stock Units \| Share Based Compensation Award Tranche Two
Class of Stock [Line Items]
Vesting period									6 months
Vesting percentage									25.00%
Award vesting grace period									1 year
Service-Based Restricted Stock Units \| Share-Based Payment Arrangement, Tranche One, First Anniversary After Grant Date, Subjected To Individual Continued Service
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									33.33%
Service-Based Restricted Stock Units \| Share-Based Payment Arrangement, Tranche Two, Second Anniversary After Grant Date, Subjected To Individual Continued Service
Class of Stock [Line Items]
Vesting period									2 years
Vesting percentage									33.33%
Service-Based Restricted Stock Units \| Share-Based Payment Arrangement, Tranche Three, Third Anniversary After Grant Date, Subjected To Individual Continued Service
Class of Stock [Line Items]
Vesting period									3 years
Vesting percentage									33.33%
Service-Based Restricted Stock Units \| Share-Based Payment Arrangement, Tranche One, First Anniversary After Grant Date
Class of Stock [Line Items]
Vesting period									1 year
Vesting percentage									33.33%
Service-Based Restricted Stock Units \| Share-Based Payment Arrangement, Tranche Two, Following First Anniversary After Grant Date
Class of Stock [Line Items]
Vesting period									2 years
Vesting percentage									66.67%
Award vesting grace period									1 year
Common Stock
Class of Stock [Line Items]
Common stock, outstanding (in shares)						188,128,869	183,704,654	183,386,035	188,128,869	183,704,654	185,835,946	184,135,714	177,000,963
Issuance of common stock, net of issuance costs (in shares)								4,404,600
Common Stock \| At The Market Equity Offering Program Authorized March 2022
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs (in shares)								404,600
Proceeds from issuance of common stock, net of issuance costs \| $								$ 800,000
At The Market Equity Offering Program \| Maximum
Class of Stock [Line Items]
Common stock sales agreement amount \| $				$ 65,000,000
Stock Incentive Plans, 2023 And 2014
Class of Stock [Line Items]
Grant date fair value of stock options not in connection with the annual grant process \| $									$ 100,000
2023 Stock Incentive Plan
Class of Stock [Line Items]
Stock options, vested in period, fair value \| $									$ 4,100,000
2023 Stock Incentive Plan \| Share-based Payment Arrangement, Option \| Director
Class of Stock [Line Items]
Number of shares granted									315,000
2023 Stock Incentive Plan \| Performance Based Stock Options
Class of Stock [Line Items]
Number of shares granted									0
2023 Stock Incentive Plan \| Service-Based Restricted Stock Units
Class of Stock [Line Items]
Number of shares granted									210,000
2014 Stock Incentive Plan \| Share-based Payment Arrangement, Option \| Employees
Class of Stock [Line Items]
Number of shares granted									2,564,500
2014 Stock Incentive Plan \| Stock Appreciation Rights (SARs)
Class of Stock [Line Items]
Number of executives shares granted to \| executive_officer									1
2014 Stock Incentive Plan \| Stock Appreciation Rights (SARs) \| Executive Officer
Class of Stock [Line Items]
Number of shares granted									635,313
2014 Stock Incentive Plan \| Performance Based Stock Options
Class of Stock [Line Items]
Number of shares granted									0
2014 Stock Incentive Plan \| Service-Based Restricted Stock Units
Class of Stock [Line Items]
Number of shares granted									2,759,675
2014 Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock, reserved for future issuance (in shares)						4,734,495			4,734,495
Purchase price at the end of offering period					85.00%
Offering period					6 months
Maximum employee subscription rate					15.00%
Maximum employee subscription amount \| $					$ 25,000
Maximum number of shares per employee in any offering period					1,500
Number of shares issued									103,500

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash

The following table reconciles cash, cash equivalents and restricted cash reported within the Company's consolidated balance sheet to the total amounts showing in the consolidated statement of cash flows:


(in thousands)	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	53,572	$	90,466
Restricted cash included in other long-term assets	1,722		2,703
Total cash, cash equivalents and restricted cash	$	55,294	$	93,169

Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash


(in thousands)	June 30, 2023		December 31, 2022
Cash and cash equivalents	$	53,572	$	90,466
Restricted cash included in other long-term assets	1,722		2,703
Total cash, cash equivalents and restricted cash	$	55,294	$	93,169

CAPITAL STOCK, STOCK-BASED COMPENSATION AND BENEFIT PLAN - Stock-Based Compensation Expense in Consolidated Statement of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 3,490	$ 6,917	$ 5,979	$ 11,453
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	605	905	1,341	2,094
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	2,685	2,709	4,220	6,056
Restructuring
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 200	$ 3,303	$ 418	$ 3,303

Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2023	Aug. 25, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	001-36352
Entity Registrant Name	AKEBIA THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8756903
Entity Address, Address Line One	245 First Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	871-2098
Title of 12(b) Security	Common Stock, $0.00001 par value per share
Trading Symbol	AKBA
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		188,313,807
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001517022
Security Exchange Name	NASDAQ

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2023	Dec. 31, 2022	Jun. 04, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, authorized (in shares)	25,000,000	25,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, authorized (in shares)	350,000,000	350,000,000	175,000,000
Common stock, issued (in shares)	188,128,869	184,135,714
Common stock, outstanding (in shares)	188,128,869	184,135,714

ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)

6 Months Ended

Jun. 30, 2023

Payables and Accruals [Abstract]

Accrued Expenses

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


	June 30, 2023		December 31, 2022
Product revenue allowances	$	23,303	$	26,268
Product return reserves, current portion	4,626		7,789
Clinical trial costs	754		5,755
Compensation and related benefits	6,582		11,481
Operating lease liabilities, current portion	4,757		4,744
Royalties	3,198		3,804
Professional fees	2,800		1,886
Accrued manufacturing costs	5,578		4,310
Restructuring costs	334		2,751
Other	4,476		6,989
Total accrued expenses and other current liabilities	$	56,408	$	75,777

NET LOSS PER SHARE (Details) - shares	3 Months Ended		6 Months Ended
NET LOSS PER SHARE (Details) - shares	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	18,350,049	13,502,015	18,350,049	20,279,566
Outstanding common stock options and SARs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	13,753,498	13,502,015	13,753,498	13,508,217
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)	4,596,551	0	4,596,551	6,771,349

LICENSE, COLLABORATION AND OTHER REVENUE - Mitsubishi Tanabe Pharma Corporation Collaboration Agreement (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) performance_obligation	Jun. 30, 2022 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 56,376,000	$ 126,365,000	$ 96,381,000	$ 187,988,000
Other long-term liabilities	17,142,000	74,610,000	17,142,000	74,610,000	$ 16,772,000	$ 15,717,000	$ 83,141,000
Revenue recognized	0	15,503,000	0	22,105,000
Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable	525,000	56,626,000	525,000	56,626,000		$ 1,901,000		$ 19,094,000
Mitsubishi Tanabe Pharma Corporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue			4,000,000
Mitsubishi Tanabe Pharma Corporation \| License Collaboration And Other Revenue, Royalties
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	500,000	400,000	900,000	700,000
Mitsubishi Tanabe Pharma Corporation \| Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue			$ 25,000,000
Mitsubishi Tanabe Pharma Corporation \| Development And Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of performance obligations \| performance_obligation			2
Mitsubishi Tanabe Pharma Corporation \| Development And Commercialize Collaboration Agreement \| Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue			$ 15,000,000
Mitsubishi Tanabe Pharma Corporation \| Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received			20,000,000
Cost of research services			20,500,000
Milestone revenue			10,000,000
Accounts receivable	0		0
Deferred revenue	0		0
Mitsubishi Tanabe Pharma Corporation \| Development And Commercialize Research And License Agreement \| Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue			10,000,000
Mitsubishi Tanabe Pharma Corporation \| Mitsubishi Tanabe Pharma Corporation And Otsuka Pharmaceutical Company Limited \| Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable	0		0
Mitsubishi Tanabe Pharma Corporation \| Mitsubishi Tanabe Pharma Corporation Supply Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue	0		0
Other long-term liabilities	0		0
Revenue recognized	0	$ 0	3,700,000	$ 7,600,000
Mitsubishi Tanabe Pharma Corporation \| Mitsubishi Tanabe Pharma Corporation Supply Agreement \| Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up-front payments invoiced	$ 0		$ 0

LICENSE, COLLABORATION AND OTHER REVENUE - Averoa License Agreement (Details)	Dec. 22, 2022
Averoa SAS
License, collaboration and other revenue:
Supply commitment, termination, notice period	24 months

DEBT	6 Months Ended
DEBT	Jun. 30, 2023
Debt Disclosure [Abstract]
DEBT	DEBT Pharmakon Term Loans On November 11, 2019, the Company, with Keryx as guarantor, entered into a loan agreement (Loan Agreement), with BioPharma Credit PLC as collateral agent and a lender (Collateral Agent), and BioPharma Credit Investments V (Master) LP as a lender. BioPharma Credit PLC subsequently transferred its interest in the loans, solely in its capacity as a lender, to its affiliate, BPCR Limited Partnership. The Collateral Agent and the lenders are collectively referred to as Pharmakon. The Loan Agreement, as amended, consists of a secured term loan facility in an aggregate amount of up to $100.0 million (Term Loans), which was made available under two tranches: (i) the first tranche of $80.0 million (Tranche A), and (ii) the second tranche of $20.0 million (Tranche B). On November 25, 2019, the Company drew $77.3 million on Tranche A, net of fees and expenses, incurred by Pharmakon and reimbursed by the Company, or Lender Expenses. On December 10, 2020, the Company drew $20.0 million on Tranche B, net of immaterial Lender Expenses and issuance costs. Proceeds from the Term Loans may be used for general corporate purposes. The Company and Keryx entered into a Guaranty and Security Agreement with the Collateral Agent (Guaranty and Security Agreement) on the Tranche A Funding Date. Pursuant to the Guaranty and Security Agreement, the Company’s obligations under the Term Loans are unconditionally guaranteed by Keryx (Guarantee). Additionally, the obligations of the Company and Keryx under the Term Loans and the Guarantee are secured by a first priority lien on certain assets of the Company and Keryx, including Auryxia and certain related assets, cash and certain equity interests held by the Company and Keryx, collectively the Collateral. The Term Loans bear interest through maturity at a variable rate, payable quarterly in arrears. Through June 30, 2023, this rate was based upon the three-month LIBOR rate plus 7.50%, subject to a 2.00% LIBOR floor and a 3.35% LIBOR cap. On June 30, 2023, the three-month LIBOR rate was above the 3.35% LIBOR cap, therefore, the Company's interest rate as of June 30, 2023 was 10.85%. On June 29, 2023, the Company and Pharmakon entered into the Third Amendment to the Loan Agreement, which replaced LIBOR with the Secured Overnight Financing Rate (SOFR), effective June 30, 2023. The three-month SOFR rate was also above the 3.35% SOFR cap and therefore, the Company's interest rate as of June 30, 2023 would still have been 10.85% should SOFR been utilized for the quarter ended June 30, 2023. On August 11, 2023, the Company received an extension from Pharmakon of the deadline in the Loan Agreement with respect to the Company's obligation to deliver quarterly financial statements for the period ended June 30, 2023 through August 28, 2023. The Term Loans will mature on November 25, 2024 (Maturity Date). The Company is required to repay the principal under the Term Loans in equal quarterly payments starting on the 33rd-month anniversary of the applicable Funding Date (Amortization Schedule). During the three and six months ended June 30, 2023, the Company made quarterly principal payments under the Term Loans totaling $8.0 million and $24.0 million, respectively. Under certain circumstances, unless certain liquidity conditions are met, the Maturity Date may decrease by up to one year, and the Amortization Schedule may correspondingly commence up to one year earlier. If the Company prepays the loan prior to the Maturity Date, it will be required to make a prepayment fee. The prepayment fee would be 1.00% on or after the third anniversary, but prior to the fourth anniversary, of the applicable Funding Date of Tranche A, and 0.50% on or after the fourth anniversary of the applicable Funding Date of Tranche A but prior to the Maturity Date, and a make-whole premium on or prior to the second anniversary of the applicable Funding Date in an amount equal to foregone interest through the second anniversary of the applicable Funding Date. A change of control, which includes a new entity or group owning a majority (greater than 50%) of the Company's voting stock, triggers a mandatory prepayment of the Term Loans. The Loan Agreement contains customary representations, warranties, events of default and covenants of the Company and its subsidiaries, including maintaining, on an annual basis, a minimum liquidity threshold which started in 2021, and on a quarterly basis, a minimum net sales threshold for Auryxia for the trailing twelve-month period of $85.0 million which started in the fourth quarter of 2020. On February 18, 2022, the Loan Agreement was amended by the First Amendment and Waiver (First Amendment and Waiver), which waived the provision under the Loan Agreement that required the Company to not be subject to any qualification as a going concern within the Company's 2021 Annual Report on Form 10-K. Pursuant to the First Amendment and Waiver, the Company's filings of Form 10-Q for fiscal quarters ending June 30, 2022 and September 30, 2022, and its future Annual Reports on Form 10-K, must not be subject to any qualification as to going concern, which requirement as to the Company's filings on Form 10-Q was waived in the Second Amendment and Waiver. If the Company does not satisfy the covenant as to going concern in any of these filings, the Company will be in default under the Loan Agreement. If an event of default occurs and is continuing under the Loan Agreement, the Collateral Agent is entitled to take enforcement action, including acceleration of amounts due under the Loan Agreement. Under certain circumstances, a default interest rate will apply on all outstanding obligations during the occurrence and continuance of an event of default. As of June 30, 2023 and December 31, 2022, the Company determined that no events of default had occurred. On July 15, 2022 (Effective Date), the Company and Pharmakon entered into the Second Amendment and Waiver (Second Amendment and Waiver), which amended and waived certain provisions of the Loan Agreement, as amended by the First Amendment and Waiver. In addition, in connection with the Second Amendment and Waiver, on the Effective Date, the Company made a $5.0 million prepayment of the principal of the Tranche A loan, or the Second Amendment Effective Date Tranche A Prepayment, and a $20.0 million prepayment of principal of the Tranche B loan, or the Second Amendment Effective Date Tranche B Prepayment, in each case, together with any and all accrued and unpaid interest on such prepayments of principal to the Effective Date. In connection therewith, the Company also paid $0.5 million in prepayment fee under the Loan Agreement. During the three months ended September 30, 2022, the Company recorded a debt extinguishment loss of $0.9 million. See Note 12 of the Notes to the Consolidated Financial Statements in the 2022 Annual Report on Form 10-K/A for further details. The Company assessed the terms and features of the Loan Agreement in order to identify any potential embedded features that would require bifurcation or any beneficial conversion feature. As part of this analysis, the Company assessed the economic characteristics and risks of the Loan Agreement, including put and call features. The terms and features assessed include a potential extension to the interest-only period dependent on both no event of default having occurred and continuing and the Company achieving certain regulatory and revenue conditions. The Company also assessed the acceleration of the obligations under the Loan Agreement under an event of default. In addition, under certain circumstances, a default interest rate will apply on all outstanding obligations during the occurrence and continuance of an event of default. In accordance with ASC 815, the Company concluded that these features are not clearly and closely related to the host instrument, and represent a single compound embedded derivative that is required to be re-measured at fair value on a quarterly basis. The fair value of the embedded debt derivative related to the Company’s Loan Agreement with Pharmakon was $0.8 million as of June 30, 2023 and December 31, 2022. The Company classified the embedded debt derivative as a long-term liability on the unaudited condensed consolidated balance sheet as of June 30, 2023. The Company recognized interest expense related to the Loan Agreement of $1.6 million and $2.7 million during the three months ended June 30, 2023 and 2022, respectively, and $3.3 million and $5.4 million during the six months ended June 30, 2023 and 2022, respectively. Unamortized discount and issuance costs were $0.5 million as of June 30, 2023.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details