Travere Therapeutics (TVTX) 10-K 20 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Feb. 15, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36257
Entity Registrant Name	TRAVERE THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-4842691
Entity Address, Address Line One	3611 Valley Centre Drive
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	888
Local Phone Number	969-7879
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	TVTX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float				$ 1,145,413,509
Entity Common Stock, Shares Outstanding			76,098,485
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE: Portions of the Proxy Statement for the registrant’s 2024 Annual Meeting of Stockholders, to be filed within 120 days after the conclusion of the registrant's fiscal year ended December 31, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Central Index Key	0001438533
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Auditor Firm ID	42	243

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Audit Information [Abstract]
Auditor Firm ID	42	243
Auditor Name	Ernst & Young LLP	BDO USA, P.C.
Auditor Location	San Diego, California	San Diego, California

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 58,176	$ 61,688
Marketable debt securities, at fair value	508,675	388,557
Accounts receivable, net	21,179	16,646
Inventory, net	9,410	4,523
Prepaid expenses and other current assets	19,335	12,033
Current assets of discontinued operations	0	2,990
Total current assets	616,775	486,437
Long-term inventory, net	31,494	0
Property and equipment, net	7,479	9,049
Operating lease right of use assets	18,061	21,000
Intangible assets, net	104,443	97,073
Other assets	10,661	10,684
Non-current assets of discontinued operations	0	48,342
Total assets	788,913	672,585
Current liabilities:
Accounts payable	41,675	17,290
Accrued expenses	118,991	95,742
Deferred revenue, current portion	7,096	11,976
Operating lease liabilities, current portion	4,909	4,433
Other current liabilities	5,237	5,722
Current liabilities of discontinued operations	0	7,000
Total current liabilities	177,908	142,163
Convertible debt	377,263	375,545
Deferred revenue, less current portion	1,835	10,931
Operating lease liabilities, less current portion	22,612	27,510
Other non-current liabilities	8,485	9,385
Non-current liabilities of discontinued operations	0	64,200
Total liabilities	588,103	629,734
Commitments and contingencies (See Note 11)
Stockholders' Equity:
Preferred stock $0.0001 par value; 20,000,000 shares authorized; no shares issued and outstanding as of December 31, 2023 and 2022	0	0
Common stock $0.0001 par value; 200,000,000 shares authorized; 75,367,117 and 64,290,570 issued and outstanding as of December 31, 2023 and 2022, respectively	7	6
Additional paid-in capital	1,327,881	1,059,975
Accumulated deficit	(1,125,622)	(1,014,223)
Accumulated other comprehensive loss	(1,456)	(2,907)
Total stockholders' equity	200,810	42,851
Total liabilities and stockholders' equity	$ 788,913	$ 672,585

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	75,367,117	64,290,570
Common stock, shares outstanding (in shares)	75,367,117	64,290,570

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total revenue	$ 145,238	$ 109,460	$ 131,836
Operating expenses:
Cost of goods sold	11,450	4,420	3,818
Research and development	244,990	227,333	201,159
Selling, general and administrative	265,542	197,520	126,284
Restructuring	11,394	0	0
Total operating expenses	533,376	429,273	331,261
Operating loss	(388,138)	(319,813)	(199,425)
Other income (expenses), net:
Interest income	21,768	6,276	1,993
Interest expense	(11,334)	(11,014)	(19,682)
Other income, net	1,594	974	231
Loss on extinguishment of debt	0	(7,578)	0
Total other income (expense), net	12,028	(11,342)	(17,458)
Loss from continuing operations before income tax provision	(376,110)	(331,155)	(216,883)
Income tax provision on continuing operations	(223)	(313)	(409)
Loss from continuing operations, net of tax	(376,333)	(331,468)	(217,292)
Income from discontinued operations, net of tax	264,934	52,986	37,201
Net loss	$ (111,399)	$ (278,482)	$ (180,091)
Basic and diluted:
Net loss from continuing operations, basic (in dollars per share)	$ (5.07)	$ (5.20)	$ (3.63)
Net loss from continuing operations, diluted (in dollars per share)	(5.07)	(5.20)	(3.63)
Net income from discontinued operations, basic (in dollars per share)	3.57	0.83	0.62
Net income from discontinued operations, diluted (in dollars per share)	3.57	0.83	0.62
Net income (loss) per common share, basic (in dollars per share)	(1.50)	(4.37)	(3.01)
Net income (loss) per common share, diluted (in dollars per share)	$ (1.50)	$ (4.37)	$ (3.01)
Weighted average common shares outstanding, basic (in shares)	74,267,418	63,758,515	59,832,287
Weighted average common shares outstanding, diluted (in shares)	74,267,418	63,758,515	59,832,287
Comprehensive loss:
Net loss	$ (111,399)	$ (278,482)	$ (180,091)
Unrealized loss on defined benefit pension plan	(374)	(368)	0
Foreign currency translation (loss) gain	(1,871)	507	1,515
Unrealized gain (loss) on marketable debt securities	3,696	(2,484)	(1,175)
Comprehensive loss	(109,948)	(280,827)	(179,751)
Net product sales
Total revenue	127,537	97,970	115,122
Operating expenses:
Cost of goods sold	8,406	4,420	3,818
License and collaboration revenue
Total revenue	17,701	11,490	16,714
Operating expenses:
Cost of goods sold	$ 3,044	$ 0	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Underwritten Equity Offering	At-The-Market Offering	Common Stock	Common Stock Underwritten Equity Offering	Common Stock At-The-Market Offering	Additional Paid-in Capital	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment	Additional Paid-in Capital Underwritten Equity Offering	Additional Paid-in Capital At-The-Market Offering	Accumulated Other Comprehensive Loss	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Accounting Standards Update [Extensible List]	Accounting Standards Update 2020-06 Cumulative Effect, Period of Adoption [Member]
Beginning balance (in shares) at Dec. 31, 2020					52,248,431
Beginning balance at Dec. 31, 2020	$ 211,213				$ 5			$ 797,985				$ (902)	$ (585,875)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	29,862							29,862
Issuance of common stock under the equity incentive plan and proceeds from exercise (in shares)					1,302,966
Issuance of common stock under the equity incentive plan and proceeds from exercise	12,841							12,841
Employee stock purchase program stock purchase and expense (in shares)					166,961
Employee stock purchase program stock purchase and expense	3,012							3,012
Issuance of common stock/equity offering, net of issuance costs (in shares)						7,532,500	1,240,640
Equity offering, net of issuance costs			$ 189,279	$ 35,656		$ 1				$ 189,278	$ 35,656
Unrealized loss on defined benefit pension plan	0
Foreign currency translation adjustments	1,515											1,515
Unrealized (loss) gain on marketable debt securities	(1,175)											(1,175)
Net loss	(180,091)												(180,091)
Ending balance (in shares) at Dec. 31, 2021					62,491,498
Ending balance at Dec. 31, 2021	302,112				$ 6			1,068,634				(562)	(765,966)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	37,897							37,897
Issuance of common stock under the equity incentive plan and proceeds from exercise (in shares)					935,598
Issuance of common stock under the equity incentive plan and proceeds from exercise	4,585							4,585
Employee stock purchase program stock purchase and expense (in shares)					161,874
Employee stock purchase program stock purchase and expense	4,259							4,259
Issuance of common stock/equity offering, net of issuance costs (in shares)							701,600
Equity offering, net of issuance costs				$ 19,545							$ 19,545
Unrealized loss on defined benefit pension plan	(368)											(368)
Foreign currency translation adjustments	507											507
Unrealized (loss) gain on marketable debt securities	(2,484)											(2,484)
Net loss	(278,482)												(278,482)
Ending balance (in shares) at Dec. 31, 2022					64,290,570
Ending balance at Dec. 31, 2022	42,851	$ (44,720)			$ 6			1,059,975	$ (74,945)			(2,907)	(1,014,223)	$ 30,225
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	43,985							43,985
Issuance of common stock under the equity incentive plan and proceeds from exercise (in shares)					1,046,276
Issuance of common stock under the equity incentive plan and proceeds from exercise	3,240							3,240
Employee stock purchase program stock purchase and expense (in shares)					326,521
Employee stock purchase program stock purchase and expense	4,853							4,853
Issuance of common stock/equity offering, net of issuance costs (in shares)						9,703,750
Equity offering, net of issuance costs			$ 191,199			$ 1				$ 191,198
Pre-funded common stock warrants, net of issuance costs	24,630							24,630
Unrealized loss on defined benefit pension plan	(374)											(374)
Foreign currency translation adjustments	(1,871)											(1,871)
Unrealized (loss) gain on marketable debt securities	3,696											3,696
Net loss	(111,399)												(111,399)
Ending balance (in shares) at Dec. 31, 2023					75,367,117
Ending balance at Dec. 31, 2023	$ 200,810				$ 7			$ 1,327,881				$ (1,456)	$ (1,125,622)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pre-funded common stock warrants, issuance costs	$ 1.6
Underwritten Equity Offering
Issuance costs	$ 12.6		$ 12.2
At-The-Market Offering
Issuance costs		$ 0.6	$ 1.1

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended				12 Months Ended			35 Months Ended
	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022
Cash Flows From Operating Activities:
Net loss	$ (90,173)	$ (86,331)	$ (65,823)	$ (75,971)	$ (111,399)	$ (278,482)	$ (180,091)
Net income from discontinued operations	(1,577)	10,233	19,813	5,775	264,934	52,986	37,201
Net loss from continuing operations	(88,596)	(96,564)	(85,636)	(81,746)	(376,333)	(331,468)	(217,292)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization					38,530	20,719	12,746
Share based compensation					44,246	38,143	29,566
Loss on extinguishment of debt					0	7,578	0
Loss on allowance for inventory					3,039	1,039	498
Amortization of debt discount and issuance costs					1,718	1,622	11,242
Amortization of (discounts) premiums on investments					(7,456)	(700)	2,008
Other					(3,626)	1,346	4,219
Changes in operating assets and liabilities:
Accounts receivable					(11,264)	(1,060)	853
Inventory					(39,420)	(1,209)	117
Tax receivable					(35)	(374)	17,099
Prepaid expenses and other current and non-current assets					(4,657)	(5,196)	(1,439)
Change in lease assets and liabilities, net					(986)	(984)	5,577
Accounts payable					24,763	2,055	2,467
Accrued expenses					22,321	22,181	16,678
Deferred revenue, current and non-current					(15,779)	(12,929)	38,300
Other current and non-current liabilities					(418)	(1,609)	1,123
Net cash used in operating activities - continuing operations					(325,357)	(260,846)	(76,238)
Net cash provided by operating activities - discontinued operations					45,336	74,555	61,446
Net cash used in operating activities					(280,021)	(186,291)	(14,792)
Cash Flows From Investing Activities:
Proceeds from the sale/maturity of marketable debt securities					334,575	381,993	433,604
Purchase of marketable debt securities					(443,942)	(385,389)	(547,076)
Purchase of fixed assets					(668)	(191)	(5,101)
Purchase of intangible assets					(41,591)	(28,366)	(19,050)
Other					0	(600)	0
Net cash used in investing activities - continuing operations					(151,626)	(32,553)	(137,623)
Net cash provided by investing activities - discontinued operations					207,402	0	0
Net cash provided by (used in) investing activities					55,776	(32,553)	(137,623)
Cash Flows From Financing Activities:
Payment of guaranteed minimum royalty					(2,100)	(2,100)	(2,100)
Proceeds from issuance of 2029 convertible senior notes					0	316,250	0
Payment of debt issuance costs					0	(9,882)	0
Repurchase of 2025 convertible senior notes including premium					0	(211,324)	0
Proceeds from the issuance of common stock, net of issuance costs					191,198		189,278	$ 0
Proceeds from the issuance of pre-funded warrants, net of issuance costs					24,630		0	0
Proceeds from exercise of stock options					3,240	4,585	12,841
Proceeds from the issuances under the employee stock purchase program					3,166	2,978	2,112
Net cash provided by financing activities - continuing operations					220,134	120,052	237,787
Net cash used in financing activities - discontinued operations					(1,382)	(2,479)	(6,104)
Net cash provided by financing activities					218,752	117,573	231,683
Effect of exchange rate changes on cash					1,981	(2,794)	1,713
Net (decrease) increase in cash and cash equivalents					(3,512)	(104,065)	80,981
Cash and cash equivalents, beginning of year		$ 61,688		$ 165,753	61,688	165,753	84,772
Cash and cash equivalents, end of year	$ 58,176		$ 61,688		58,176	61,688	165,753	$ 61,688
Supplemental Disclosure of Cash Flow Information:
Operating cash flows used for operating leases					6,315	6,020	2,205
Cash paid for interest					8,838	10,159	7,327
Cash (paid) refunded for income taxes					(578)	(996)	16,420
Non-cash investing and financing activities:
Accrued royalty in excess of minimum payable to the sellers of Thiola					16,206	16,067	19,362
At-The-Market Offering
Cash Flows From Financing Activities:
Proceeds from the issuance of common stock, net of issuance costs						20,100
Proceeds from issuance of common stock					$ 0	$ 19,545	$ 35,656

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	DESCRIPTION OF BUSINESS Organization and Description of Business Travere Therapeutics, Inc. (“we”, “our”, “us”, “Travere” and the “Company”) refers to Travere Therapeutics, Inc., a Delaware corporation, as well as its subsidiaries. Travere is a fully integrated biopharmaceutical company headquartered in San Diego, California focused on identifying, developing and delivering life-changing therapies to people living with rare kidney and metabolic diseases. The Company regularly evaluates and, where appropriate, acts on opportunities to expand its product pipeline through licenses and acquisitions of products in areas that will serve patients with serious unmet medical need and that the Company believes offer attractive growth characteristics. Discontinued Operations - Sale of Bile Acid Product Portfolio On July 16, 2023, Travere entered into an Asset Purchase Agreement (the “Purchase Agreement”) with Mirum Pharmaceuticals, Inc. ("Mirum Pharmaceuticals" or “Mirum”), pursuant to which Mirum agreed to purchase from Travere substantially all of the assets primarily related to Travere’s business of development, manufacture (including synthesis, formulation, finishing or packaging) and commercialization of Chenodal and Cholbam (also known as Kolbam, and together with Chenodal, the “Products”), collectively, the "bile acid business". On August 31, 2023, the Company and Mirum consummated the transactions contemplated by the Purchase Agreement (the “Closing”). In connection with the Closing, Mirum paid Travere an upfront cash payment of $210.0 million. Pursuant to the Purchase Agreement, Travere is eligible to receive up to $235.0 million upon the achievement of certain milestones based on specified amounts of annual net sales (tiered from $125.0 million to $500.0 million) of the Products. The Company has reflected the bile acid business as a discontinued operation in the Consolidated Financial Statements for all periods presented. See Note 19 for further discussion. Unless otherwise noted, amounts and disclosures throughout the Notes to the Consolidated Financial Statements relate to the Company's continuing operations. Approved Products: FILSPARI® (sparsentan) On February 17, 2023, the U.S. Food and Drug Administration (the "FDA") granted accelerated approval of FILSPARI® (sparsentan) to reduce proteinuria in adults with primary IgAN at risk of rapid disease progression, generally a UPCR ≥1.5 gram/gram. FILSPARI, a once-daily, oral medication is designed to selectively target two critical pathways (endothelin 1 and angiotensin-II) in the disease progression of IgAN. This indication was granted under accelerated approval based on reduction in proteinuria. The continued approval of FILSPARI may be contingent upon confirmation of a clinical benefit in the Company's Phase 3 clinical trial of sparsentan for the treatment of IgAN (the "PROTECT Study"). In September 2023, the Company announced topline two-year confirmatory secondary endpoint results from the PROTECT Study and i n December 2023, the Company announced the completion of a successful pre-NDA meeting with the FDA for FILSPARI in IgAN. Following its regulatory engagement, the Company plans to submit a supplemental New Drug Application (sNDA) for conversion of the existing U.S. accelerated approval of FILSPARI to full approval. In August 2022, the Company and Vifor (International) Ltd. ("CSL Vifor"), with whom the Company entered into a license and collaboration agreement ("License Agreement") in September 2021, announced that the European Medicines Agency (the "EMA") had accepted for review the MAA of sparsentan for the treatment of IgAN in the EU. The Company is awaiting an opinion by the Committee for Medicinal Products for Human Use (the "CHMP"). Thiola® and Thiola EC® (tiopronin tablets) Thiola® and Thiola EC® (tiopronin tablets) are approved in the United States for the prevention of cystine (kidney) stone formation in patients with severe homozygous cystinuria. Clinical-Stage Programs: Sparsentan for the treatment of FSGS Sparsentan remains a novel investigational product candidate which has been granted Orphan Drug Designation for the treatment of focal segmental glomerulosclerosis (FSGS) in the U.S. and the EEA. In December 2023, the Company announced that it had completed its planned Type C meeting with the FDA to discuss previously reported results from the Phase 3 DUPLEX Study of sparsentan in FSGS. The FDA acknowledged the high unmet need for approved therapies as well as the challenges in studying FSGS but indicated that the two-year results from the Phase 3 DUPLEX Study alone were not sufficient to support an sNDA submission. Together with CSL Vifor, the Company also plans to engage with the EMA to determine the potential for a subsequent variation to the Conditional Marketing Authorization (CMA) of sparsentan for the treatment of FSGS, subject to a review decision on the pending application for CMA of sparsentan in IgAN. The Company is conducting additional analyses of FSGS data and intends to engage with regulators to evaluate potential regulatory pathways for a sparsentan FSGS indication. Pegtibatinase Pegtibatinas e is a novel investigational human enzyme replacement candidate being evaluated for the treatment of classical homocystinuria (HCU). Pegtibatinase has been granted Rare Pediatric Disease, Fast Track and Breakthrough Therapy designations by the FDA, as well as orphan drug designation in the United States and European Union. In May 2023, the Company announced positive topline results from cohort 6 in the Phase 1/2 COMPOSE Study. In December 2023, the Company initiated the pivotal Phase 3 HARMONY Study to support the potential approval of pegtibatinase for the treatment of classical HCU. The HARMONY Study is a global, randomized, multi-center, double-blind, placebo-controlled Phase 3 clinical trial designed to evaluate the efficacy and safety of pegtibatinase as a novel treatment to reduce total homocysteine (tHcy) levels. Topline results from the HARMONY Study are expected in 2026. The Company acquired pegtibatinase as part of the November 2020 acquisition of Orphan Technologies Limited. Preclinical Programs: The Company is a participant in a Cooperative Research and Development Agreement ("CRADA"), which forms a multi-stakeholder approach to pool resources with leading experts and incorporate the patient perspective early in the therapeutic identification and development process. The Company is partnering with the National Institutes of Health’s National Center for Advancing Translational Sciences ("NCATS") and a leading patient advocacy organization, Alagille Syndrome Alliance, aimed at the identification of potential small molecule therapeutics for Alagille syndrome ("ALGS"). There are no treatment options currently approved for ALGS. The Company is party to a collaboration agreement with PharmaKrysto Limited and their early-stage cystinuria discovery program, whereby the Company is responsible for funding all research and development expenses for the pre-clinical activities associated with the cystinuria program.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES A summary of the significant accounting policies applied in the preparation of the accompanying consolidated financial statements follows: Principles of Consolidation The consolidated financial statements represent the consolidation of the accounts of the Company, its subsidiaries and variable interest entities for which the Company has been determined to be the primary beneficiary, in conformity with accounting principles generally accepted in the United States ("U.S. GAAP"). All intercompany accounts and transactions have been eliminated in consolidation. See Note 5 for further discussion of variable interest entities (“VIE”) that the Company consolidates. Use of Estimates In preparing financial statements in conformity with U.S. GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates. On an ongoing basis, the Company evaluates its estimates and assumptions. These estimates and assumptions include revenue recognition, forecasting probability-weighted cash flows based upon estimates of forecasted revenues, clinical and regulatory timelines and discount rates, valuing equity securities in share-based payments, estimating expenses of contracted research organizations, estimating reserves for inventory, estimating the useful lives of depreciable and amortizable assets, estimating of valuation allowances and uncertain tax positions, and estimates associated with the assessment of impairment for long-lived assets. Revenue Recognition The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Accounting Standards Codification ("ASC") 606, Revenue from Contracts with Customers ("ASC 606"), the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only recognizes revenue from contracts when it is probable that the entity will collect substantially all the consideration it is entitled to in exchange for the goods or services it transfers to the customer. See Note 3 and Note 4 for further discussion. Payments received under collaboration and licensing agreements may include non-refundable fees at the inception of the arrangements, milestone payments for specific achievements and royalties on the sale of products. At the inception of arrangements that include milestone payments, the Company uses judgement to evaluate whether the milestones are probable of being achieved and estimates the amount to include in the transaction price utilizing the most likely amount method. If it is probable that a significant revenue reversal will not occur, the estimated amount is included in the transaction price. Milestone payments that are not within the Company or the licensee’s control, such as regulatory approvals, are considered to be constrained due to a high degree of uncertainty and are not included in the transaction price until such uncertainty is resolved. At the end of each reporting period, the Company re-evaluates the probability of achievement of development milestones and any related constraint and adjusts the estimate of the overall transaction price, if necessary. The Company recognizes aggregate sales-based milestones and royalty payments from product sales of which the license is deemed to be the predominant item to which the royalties relate, at the later of when the related sales occur or when the performance obligation to which the sales-based milestone or royalty has been allocated has been satisfied. Revenue from collaboration and licensing agreements may also include sales of inventory, at cost plus a margin, which is recorded in license and collaboration revenue. The Company utilizes significant judgement to develop estimates of the stand-alone selling price for each distinct performance obligation based upon the relative stand-alone selling price. Variable consideration that relates specifically to the Company’s efforts to satisfy specific performance obligations is allocated entirely to those performance obligations. The stand-alone selling price for license-related performance obligations requires judgement in developing assumptions to project probability-weighted cash flows based upon estimates of forecasted revenues, clinical and regulatory timelines and discount rates. The stand-alone selling price for clinical development performance obligations is based on forecasted expected costs of satisfying a performance obligation plus an appropriate margin. If the licenses to intellectual property are determined to be distinct from the other performance obligations identified in the arrangement and have stand-alone functionality, the Company recognizes revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to benefit from the license. For licenses that are not distinct from other promises, the Company applies judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, upfront fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the related revenue recognition accordingly. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. Revenue is recorded proportionally as costs are incurred. The Company generally utilizes the cost-to-cost method of progress because it best measures the transfer of control to the customer which occurs as the Company incurs costs. Under the cost-to-cost measure of progress, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. The Company uses judgment to estimate the total costs expected to complete the clinical development performance obligations, which include subcontractor costs, labor, materials, other direct costs and an allocation of indirect costs. The Company evaluates these cost estimates and the progress each reporting period and adjusts the measure of progress, if necessary. Inventory, Related Reserves and Cost of Goods Sold Inventory, which is recorded at the lower of cost or net realizable value, includes materials and other direct and indirect costs and is valued using the first-in, first-out method. The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value, and writes down such inventory as appropriate. In addition, the Company's products are subject to strict quality control and monitoring which the Company’s manufacturers perform throughout their manufacturing process. The Company does not directly manufacture any product. The Company has a single supplier for its product Thiola, and utilizes contract service providers for the manufacture of the active pharmaceutical ingredient for FILSPARI and the manufacture of primary packaging, secondary packaging and serialization for its product FILSPARI. The inventory reserve was $2.4 million and zero at December 31, 2023 and 2022, respectively. Inventory, net of reserves, consisted of the following at December 31, 2023 and 2022 ( in thousands ): December 31, 2023 December 31, 2022 Raw materials $ 33,790 $ 2,397 Work in process 4,727 — Finished goods 2,387 2,126 Total inventory $ 40,904 $ 4,523 Classified as: Inventory, net $ 9,410 $ 4,523 Long-term inventory, net 31,494 — Total inventory $ 40,904 $ 4,523 The balance classified as long-term inventory consists of raw materials and work in process for FILSPARI as of December 31, 2023. The Company maintains levels of these inventories beyond a one-year production plan to limit exposure to potential supply disruption. Such inventories are classified as long-term. Cost of goods sold includes the cost of inventory sold, third party manufacturing and supply chain costs, product shipping, tracking and handling costs, and provisions for excess and obsolete inventory. Cost of goods sold also includes the cost of goods sold under the Company's license and collaboration agreements, which currently consists of the sale of active pharmaceutical ingredients to the Company's collaboration partner, at cost plus a margin. The following table summarizes cost of goods sold for the years ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Cost of goods sold - product sales $ 8,406 $ 4,420 $ 3,818 Cost of goods sold - license and collaboration 3,044 — — Total cost of goods sold $ 11,450 $ 4,420 $ 3,818 Capitalization of Inventory Costs Prior to the regulatory approval of the Company's therapeutic candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those therapies. The Company capitalizes inventory costs associated with its products after regulatory approval, when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Until the date at which regulatory approval has been received, costs related to the production of inventory are recorded as research and development expenses as incurred. Any eventual sale of previously expensed ("zero-cost") inventories may impact future margins, for any periods in which those inventories are sold. Prior to the February 2023 FDA accelerated approval of FILSPARI (sparsentan), the Company recognized approximately $7.5 million in research and development expenses related to the production of active pharmaceutical ingredients to support the commercial launch of FILSPARI. For the year ended December 31, 2023, sales of FILSPARI primarily consisted of zero-cost inventories. As of December 31, 2023, the Company had $7.2 million of zero-cost inventory remaining. The Company expects to continue to benefit from the sale of previously expensed inventories through at least 2025. The Company began capitalizing inventory costs associated with FILSPARI (sparsentan) following the February 2023 approval for treatment in IgAN. At December 31, 2023, the Company's evaluation of excess inventory and obsolescence considered certain minimum purchase obligations, which in combination with lower forecasted sales of FILSPARI resulted in a $3.2 million charge to cost of goods sold. The charge to cost of goods of sold included a $2.1 million write-down of inventory balances and $1.1 million accrued for firm purchase commitments. Research and Development Expenses Research and development includes expenses related to sparsentan, pegtibatinase, and the Company's other pipeline programs. The Company expenses all research and development costs as they are incurred. The Company's research and development costs are composed of salaries and bonuses, benefits, share-based compensation, license fees, milestones under license agreements, costs paid to third-party contractors to perform research, conduct clinical trials, costs to develop drug materials and delivery devices, costs to manufacture drug product supplies to support clinical development, and associated overhead expenses and facilities costs. The Company charges direct internal and external program costs to the respective development programs. The Company also incurs indirect costs that are not allocated to specific programs because such costs benefit multiple development programs and allow us to increase our pharmaceutical development capabilities. These consist of internal shared resources related to the development and maintenance of systems and processes applicable to all of our programs. Nonrefundable advance payments for goods and services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. During the three months ended December 31, 2022, the Company recorded an out of period adjustment that decreased research and development expenses and related accrued expenses by $7.7 million, $1.5 million of which was previously recorded in fiscal year 2022 and $6.2 million that was originally recorded in fiscal year 2021. The adjustment was the result of a certain pre-launch inventory contract that was not properly evaluated for accounting implications at inception. The Company evaluated the impact of the adjustment and concluded it is not material, individually and in the aggregate, to 2022 or any prior period financial statements. Clinical Trial Expenses The Company records expenses in connection with its clinical trials under contracts with contract research organizations ("CROs") that support conducting and managing clinical trials, as well as contract manufacturing organizations ("CMOs") for the manufacture of drug product supplies to support clinical development. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up, initiation activities, enrollment, treatment of patients, or the completion of other clinical trial activities, and in the case of CMOs, costs associated with the production of drug product supplied and the procurement of raw materials to be consumed in the manufacturing process. Expenses related to clinical trials are accrued based on our estimates of the progress of services performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials or the delivery of goods. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), the Company adjusts its estimates accordingly on a prospective basis. Revisions to the Company's contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain. The Company currently has one Phase 1/2 clinical trial and three Phase 3 clinical trials in process that are in varying stages of activity, with ongoing non-clinical support trials. As such, clinical trial expenses will vary depending on all the factors set forth above and may fluctuate significantly from quarter to quarter. Share-Based Compensation The Company recognizes all employee share-based compensation as a cost within research and development expenses and selling, general, and administrative expenses. Equity-classified awards principally related to stock options, restricted stock units (“RSUs”) and performance stock units ("PSUs"), are measured at the grant date fair value of the award. The Company determines grant date fair value of stock option awards using the Black-Scholes option-pricing model. The fair value of RSUs and PSUs are determined using the closing price of the Company’s common stock on the grant date. For service based vesting grants, expense is recognized over the requisite service period. For PSUs, expense is recognized over the implicit service period, assuming vesting is probable. No expense is recognized for PSUs if it is not probable the vesting criteria will be satisfied. Forfeitures are accounted for as they occur. Expiration Term Vesting Term Stock Options 10 years 3 to 4 years Restricted Stock Units ---- 1 to 4 years Earnings (Loss) Per Share The Company calculates basic earnings per share by dividing net income/(loss) by the weighted average number of shares outstanding during the period. Pre-funded warrants issued and sold by the Company to purchase shares of its common stock are included in the calculation of basic net loss per common share if the exercise price of the pre-funded warrant represents little consideration and is non-substantive in relation to the price paid for the warrant, and if the warrants are immediately exercisable with no further vesting conditions or contingencies associated with them. The Company's diluted earnings/(loss) per share computation includes the effect, if any, of shares that would be issuable upon the exercise of outstanding stock options, convertible debt and RSUs, reduced by the number of shares which are assumed to be purchased by the Company from the resulting proceeds at the average market price during the year, when such amounts are dilutive to the earnings per share calculation. In accordance with ASC 260, Earnings per Share , if a company had a discontinued operation, the company uses income from continuing operations, adjusted for preferred dividend and similar adjustments, as its control number to determine whether potential common shares are dilutive. Cash and Cash Equivalents The Company considers all highly liquid marketable securities with an original maturity of three months or less to be cash equivalents. Due to the short-term maturity of such investments, the carrying amounts are a reasonable estimate of fair value. Concentration of Credit Risk The Company maintains its cash and cash equivalents at insured financial institutions, the balances of which may, at times, exceed federally insured limits. Generally, these deposits may be redeemed upon demand, and the Company believes there is minimal risk of losses on such balances. The Company monitors its investments with counterparties with the objective of minimizing concentrations of credit risk. The Company's investment policy is to invest only in institutions that meet high credit quality standards and established limits on the amount and time to maturity of investments with any individual counterparty. The policy also requires that investments are only entered into with corporate and financial institutions that meet high quality standards. Marketable Debt Securities The Company classified marketable debt securities held as “available-for-sale” and carries them at fair value. The Company classifies these investments as current assets, even if the maturity when acquired by the Company is greater than one year due to the ability to liquidate within the next 12 months. The amortized cost of marketable debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, is included in interest income. Unrealized gains and losses on marketable debt securities are recorded as a separate component of stockholders’ equity as accumulated other comprehensive loss, unless an impairment is determined to be the result of credit-related factors or the Company intends to sell the security or it is more likely than not that the Company will be required to sell the security before recovery. Unrealized losses that are determined to be credit-related are recorded as an allowance against the amortized cost basis. Realized gains or losses on debt security transactions and declines in value that are determined to be the result of credit losses, if any, are reported in other income or expense in the Consolidated Statements of Operations and Comprehensive Loss. The cost of securities sold is based on the specific identification method. Marketable debt securities are maintained at one financial institution and are governed by the Company’s investment policy. See Note 6 for further discussion. Accounts Receivables, Net Trade accounts receivable are recorded net of reserves for prompt pay discounts and expected credit losses. Estimates for allowances for credit losses are determined based on existing contractual obligations, historical payment patterns and individual customer circumstances. The allowance for credit losses was zero at both December 31, 2023 and 2022, respectively. For the years ended December 31, 2023, 2022 and 2021, bad debt expense recorded in the Consolidated Statements of Operations and Comprehensive Loss was immaterial. The Company's evaluation of credit losses for the current period included an assessment of our aged trade receivables balances and their underlying credit risk characteristics. Our evaluation of past events, current conditions, and reasonable and supportable forecasts about the future resulted in an expectation of immaterial credit losses. Supplier Concentration Risk The Company has no manufacturing capabilities and relies on third party manufacturers who are sole source suppliers for manufacturing of its products. The Company intends to rely on third-party manufacturers for the long-term commercial supply of FILSPARI and for its development stage product candidates, including sparsentan for the treatment of FSGS and pegtibatinase. The Company expects the manufacturers of each product or product candidate to, at least initially and potentially for a significant period of time, be single source suppliers to the Company. Segment Information The Company currently operates in one operating segment focused on the development and commercialization of innovative therapies for people with serious and life-threatening rare diseases and medical conditions. The Company is not organized by market and is managed and operated as one business. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate products, other than revenues, and does not have separately reportable segments. Property and Equipment, net Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over the related estimated useful lives as presented in the table below. Significant additions and improvements are capitalized, while repairs and maintenance are charged to expense as incurred. Property and equipment purchased for specific research and development projects with no alternative use is expensed as incurred. The major classifications of property and equipment, including their respective expected useful lives, consist of the following: Computers and equipment 3 years Furniture and fixtures 7 years Leasehold improvements Shorter of length of lease or life of the asset Leases The Company determines whether a contract is, or contains, a lease at inception. The Company classifies each of its leases as operating or financing considering factors such as the length of the lease term, the present value of the lease payments, the nature of the asset being leased, and the potential for ownership of the asset to transfer during the lease term. Leases with terms greater than one year are recognized on the Consolidated Balance Sheets as Right-of-use assets and Lease liabilities and are measured at the present value of the fixed payments due over the expected lease term minus the present value of any incentives, rebates or abatement expected to be received from the lessor. Options to extend a lease are typically excluded from the expected lease term as the exercise of the option is typically not reasonably certain. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the appropriate incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis an amount equal to the lease payments over a similar term and in a similar economic environment. In addition to rent, the leases may require the Company to pay additional amounts for taxes, insurance, maintenance, and other expenses, which are generally referred to as non-lease components. The Company has elected to not separate lease and non-lease components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease component and recognized as part of the Right-of-use assets and Lease liabilities. The Company records expense to recognize fixed lease payments, including payment escalation, on a straight-line basis over the expected lease term. Costs determined to be variable and not based on an index or rate are not included in the measurement of the lease liability and are expensed as incurred. The Company has made an accounting policy election to not recognize short-term leases, or leases that have a lease term of 12 months or less at commencement date, within its Consolidated Balance Sheets and to recognize those lease payments in the Consolidated Statements of Operations and Comprehensive Loss on a straight-line basis over the lease term. Intangible Assets, Net The Company's intangible assets consist of licenses and purchased technology. Intangible assets with definite lives are amortized on a straight-line basis over their estimated useful lives and are reviewed periodically for impairment. Intangible Assets with Cost Accumulation Model In 2014, the Company entered into a license agreement with Mission Pharmacal in which the Company obtained the exclusive right to license the trademark of Thiola. The acquisition of the Thiola license qualified as an asset acquisition under the principles of ASC 805, Business Combinations ("ASC 805") in effect at the time of acquisition. The license agreement requires the Company to make royalty payments based on net sales of Thiola. The liability for royalties in excess of the annual contractual minimum is recognized in the period in which the royalties become probable and estimable, which is typically in the period corresponding with the respective sales. The Company records an offsetting increase to the cost basis of the asset under the cost accumulation model ("Thiola Intangible"). The additional cost basis is subsequently amortized over the remaining useful life. In the second quarter of 2023, the Company reduced the estimated useful life of the Thiola Intangible to better reflect the pattern of projected future cash flows, resulting in incremental expense of $3.7 million recorded in selling, general, and administrative Consistent with all prior periods since Thiola was acquired, the Company has not accrued any liability for future royalties in excess of the annual contractual minimum at December 31, 2023 as such royalties are not yet probable and estimable. Variable Interest Entity The Company reviews each investment and collaboration agreement to determine if it has a variable interest in the entity. In assessing whether the Company has a variable interest in the entity as a whole, the Company considers and makes judgements regarding the purpose and design of the entity, the value of the licensed assets to the entity, the value of the entity’s total assets and the significant activities of the entity. If the Company has a variable interest in the entity as a whole, the Company assesses whether or not the Company is a primary beneficiary of that VIE, based on a number of factors, including: (i) which party has the power to direct the activities that most significantly affect the VIE’s economic performance, (ii) the parties’ contractual rights and responsibilities pursuant to the collaboration agreement, and (iii) which party has the obligation to absorb losses of or the right to receive benefits from the VIE that could be significant to the VIE. If the Company determines that it is the primary beneficiary of a VIE at the onset of the collaboration, the collaboration is treated as a business combination and the Company consolidates the financial statements of the VIE into the Company’s consolidated financial statements. On a quarterly basis, the Company evaluates whether it continues to be the primary beneficiary of the consolidated VIE. If the Company determines that it is no longer the primary beneficiary of a consolidated VIE, it deconsolidates the VIE in the period in which the determination is made. Assets and liabilities recorded as a result of consolidating the financial results of the VIE into the Company’s consolidated balance sheet do not represent additional assets that could be used to satisfy claims against the Company’s general assets or liabilities for which creditors have recourse to the Company’s general assets. Goodwill Goodwill represents the excess of purchase price over fair value of net assets acquired in a business combination and is not amortized. Goodwill is subject to impairment testing at least annually or when a triggering event occurs that could indicate a potential impairment. The Company has one segment and one reporting unit and as such reviews goodwill for impairment at the consolidated level. For the years ended December 31, 2023, 2022 and 2021 there were no impairments to goodwill. Impairment of Long-Lived Assets The Company's long-lived assets are primarily comprised of intangible assets, right-of-use assets, and property and equipment. The Company evaluates its finite-lived intangible assets, right-of-use assets, and property and equipment for impairment whenever events or changes in circumstances indicate the carrying value of an asset or group of assets may not be recoverable. If these circumstances exist, recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future undiscounted net cash flows expected to be generated by the use and eventual disposition of the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. In addition, indefinite-lived intangible assets are reviewed for impairment annually and whenever events or changes in circumstances indicate that it is more likely than not that the asset is impaired by comparing the fair value to the carrying value of the asset. To determine the fair value of the asset, the Company used the multi-period excess earnings method of the income approach. The more significant assumptions inherent in the application of this method include: the amount and timing of projected future cash flows (including revenue, cost of sales, research and development costs, and sales and marketing expenses), and the discount rate selected to measure the risks inherent in the future cash flows. There were no impairments related to finite-lived intangible assets in the years ended December 31, 2023, 2022 and 2021. Income Taxes The Company follows ASC 740, Income Taxes ("ASC 740"), which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance to the extent management concludes it is more likely than not that the asset will not be realized. The standard addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not

REVENUE RECOGNITION

REVENUE RECOGNITION	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Product Sales, Net Product sales consist of FILSPARI and tiopronin products (Thiola and Thiola EC). The Company sells its products to specialty pharmacies and through direct-to-patient distributors worldwide, with the United States representing 99% of net product sales. The Company sells FILSPARI to three direct-to-patient specialty pharmacies. The Company sells its other products to patients and pharmacies, with distribution facilitated through a single direct-to-patient distributor. Revenues from product sales are recognized in satisfaction of a single performance obligation when the customer obtains control of the Company’s product. For FILSPARI, sales are recognized upon delivery of the product to the specialty pharmacies. The Company receives payments from its FILSPARI sales based on terms that are generally 30 days from shipment of the product to the specialty pharmacy. For the Company's other products, product sales are recognized upon delivery to the patient. The Company receives payments from sales of its other products, primarily through third party payers, based on terms that generally are within 30 days of delivery of product to the patient. Contracts do not contain significant financing components based on the typical period of time between performance of services and collection of consideration. Deductions from Revenue Revenues from product sales are recorded at the net sales price, which includes provisions resulting from discounts, rebates and co-pay assistance that are offered to customers, payers and other indirect customers relating to the Company’s sales of its products. These provisions are based on the estimates of the amounts earned or to be claimed on the related sales. These amounts are treated as variable consideration, estimated and recognized as a reduction of the transaction price at the time of the sale, using the most likely amount method, and are classified as a reduction of accounts receivable (if the amount is payable to a customer) or as a current liability (if the amount is payable to a party other than a customer). The Company includes these estimated amounts in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized for such transactions will not occur. Where appropriate, these reserves take into consideration the Company’s historical experience, current contractual and statutory requirements and specific known market events and trends. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. If actual results in the future vary from the Company’s provisions, the Company will adjust the estimate, which would affect net product revenue and earnings in the period such variances become known. For the years ended December 31, 2023, 2022 and 2021, the Company recorded a net product revenue increase of $0.4 million, $0.2 million, and $0.2 million, respectively, related to performance obligations satisfied in previous periods. Government Rebates: The Company calculates the rebates that it will be obligated to provide to government programs and deducts these estimated amounts from its gross product sales at the time the revenues are recognized. Allowances for government rebates and discounts are established based on an estimated allocation of payers and the government-mandated discounts applicable to government-funded programs. Rebate discounts are included in accrued expenses in the accompanying consolidated balance sheets. Commercial Rebates: The Company calculates the rebates it incurs according to any contracts with certain commercial payers and deducts these amounts from its gross product sales at the time the revenues are recognized. Allowances for commercial rebates are established based on actual payer information, which is reasonably estimated at the time of delivery for applicable products. Rebate discounts are included in accrued expenses in the accompanying consolidated balance sheets. Prompt Pay Discounts: The Company offers discounts to certain customers for prompt payments. The Company accrues for the calculated prompt pay discount based on the gross amount of each invoice for those customers at the time of sale. Product Returns: Consistent with industry practice, the Company offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product’s expiration date. Historically, returns have been immaterial. Co-pay Assistance: The Company offers a co-pay assistance program, which is intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payers. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the estimated cost per claim associated with product that has been recognized as revenue. The following table summarizes net product sales for the year ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Tiopronin products $ 98,329 $ 97,970 $ 115,122 FILSPARI 29,208 — — Total net product sales $ 127,537 $ 97,970 $ 115,122

COLLABORATION AND LICENSE AGREE

COLLABORATION AND LICENSE AGREEMENTS	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
COLLABORATION AND LICENSE AGREEMENTS	COLLABORATION AND LICENSE AGREEMENTS In September 2021, the Company entered into a license and collaboration agreement (“License Agreement”) with Vifor (International) Ltd. (“CSL Vifor”), pursuant to which the Company granted an exclusive license to CSL Vifor for the commercialization of sparsentan in Europe, Australia and New Zealand ("Licensed Territories"). CSL Vifor also has first right of negotiation to expand the licensed territories into Canada, China, Brazil and/ or Mexico. Under the terms of the License Agreement, the Company received an upfront payment of $55.0 million and will be eligible for up to $135.0 million in aggregate regulatory and market access related milestone payments and up to $655.0 million in aggregate sales-based milestone payments for a total potential value of up to $845.0 million. The Company is also entitled to receive tiered double-digit royalties of up to 40 percent of annual net sales of sparsentan in the Licensed Territories. Under the License Agreement, CSL Vifor will be responsible for all commercialization activities in the Licensed Territories. The Company remains responsible for the worldwide clinical development of sparsentan through regulatory approval as defined and will retain all rights to sparsentan in the United States and rest of world outside of the Licensed Territories. Development costs for any post regulatory approval development activities, subject to approval by both parties, will be borne by the Company and CSL Vifor as defined, respectively. The License Agreement will remain in effect, unless terminated earlier, until the expiration of all royalty terms for sparsentan in the licensed territories. Each party has the right to terminate the License Agreement for the other party’s uncured material breach, insolvency or if the time required for performance under the License Agreement by the other party is extended due to a force majeure event that continues for six months or more. The Company assessed the License Agreement and determined that it meets both criteria to be considered a collaborative agreement within the Scope of ASC 808, Collaborative Arrangements of active participation by both parties and exposures to significant risks and rewards dependent on the commercial success of the activities. Both parties participate on joint steering and other committees overseeing the collaboration activities. Also, both parties are exposed to significant risks and rewards based on the economic outcomes of regulatory approvals and commercialization of sparsentan. The Company determined the transaction price under the License Agreement totaled $55.0 million, consisting of the fixed non-refundable upfront payment. The variable regulatory and access related milestones were excluded from the transaction price given the substantial uncertainty related to their achievement. Sales-based milestone payments and royalties on net sales were excluded from the transaction price and will be recognized at the later of when the related sales occur or when the performance obligation to which the sales-based milestone or royalty has been allocated have been satisfied. The Company concluded that CSL Vifor represented a customer and applied relevant guidance from ASC 606 to evaluate the accounting under the License Agreement. In accordance with this guidance, the Company concluded that the promise to grant the license is distinct from the promise to provide clinical development services resulting in two performance obligations. As a result, the Company allocated $12.0 million of the transaction price, based on the performance obligations' relative standalone selling prices, to the license, which was recognized in full in 2021. The remaining $43.0 million of the transaction price was allocated to the clinical development activities and recorded as deferred revenue, which will be recognized over the development period based upon the ratio of costs incurred to date to the total estimated costs. The Company recognized a total of $17.7 million in license and collaboration revenue for the year ended December 31, 2023, which consisted of $3.3 million from the sale of active pharmaceutical ingredients to CSL Vifor, and $14.4 million for clinical development activities, based upon the ratio of costs incurred to total estimated costs. A decrease in total costs for clinical development activities due to the restructuring announced in December 2023 resulted in a $2.9 million increase in amortization of deferred revenue under the cost-to-cost model for the year ended December 31, 2023. For the year ended December 31, 2022, the Company recognized a total of $11.5 million in license and collaboration revenue for clinical development activities, based upon the ratio of costs incurred to total estimated costs. Deferred revenue related to the clinical development activities as of December 31, 2023 was $8.9 million. Of this amount, $7.1 million was classified as current as of December 31, 2023, based upon amount expected to be realized within the next year. As of December 31, 2022, deferred revenue related to the clinical development activities was $22.9 million, of which $12.0 million was classified as current. The Company estimates that the remainder of the deferred revenue balance will be fully realized by mid-2025. The following table sets forth a summary of changes in deferred revenue for the years ended December 31, 2023, 2022 and 2021 (in thousands) : Deferred Revenue 2023 2022 2021 Balance at January 1, $ 22,907 $ 36,647 $ — New consideration resulting in deferred revenue — — 55,000 License and collaboration revenue (14,363) (11,490) (16,714) Foreign currency impact 387 (2,250) (1,639) Balance at December 31, $ 8,931 $ 22,907 $ 36,647

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	12 Months Ended
	Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
VARIABLE INTEREST ENTITIES	VARIABLE INTEREST ENTITIES Stock Purchase and Collaboration Agreement with PharmaKrysto On March 8, 2022, the Company entered into a Collaboration Agreement with PharmaKrysto Limited (“PharmaKrysto”), a privately held pre-clinical stage company related to PharmaKrysto's early-stage cystinuria discovery program, and concurrently therewith entered into a Stock Purchase Agreement with PharmaKrysto (together, the "Agreements"). Pursuant to the terms of the Agreements, the Company paid PharmaKrysto's shareholders $0.6 million in cash to purchase 5% of the outstanding common shares of PharmaKrysto and $0.4 million to PharmaKrysto as a one-time signing fee. Under the Collaboration Agreement, the Company will fund all research and development expenses for the pre-clinical activities associated with the cystinuria program, which are estimated to be approximately $5.0 million. The Agreements require the Company to purchase an additional 5% of the outstanding common shares for $1.0 million upon the occurrence of a specified pre-clinical milestone, and granted an option to the Company to purchase the remaining outstanding shares of PharmaKrysto for $5.0 million upon the occurrence of a subsequent pre-clinical milestone prior to expiration of the option on March 8, 2025. If the Company elects to exercise the option, it would be required to perform commercially reasonable clinical diligence obligations. In addition, it would be required to make cash milestone payments totaling up to an aggregate $16.0 million upon the achievement of certain development and regulatory milestones, plus tiered royalty payments of less than 4% on future net sales of a product, if approved. The Company has the right to terminate the Agreements and return the shares for a nominal price at any time upon 60 days’ notice, subject to survival of contingent obligations, if any. The Company determined that PharmaKrysto is a VIE because it lacks the resources to conduct the cystinuria clinical program and the limitation on the residual returns through the Company's option to purchase the remaining outstanding shares. The Company further concluded that it is the primary beneficiary of the VIE due to the Company's ultimate control over the research and development program, and its obligation, subject to continuation of the collaboration, to fund 100% of research and development costs of the program pursuant to the terms of the Collaboration Agreement. The upfront payments were expensed to research and development and other income (expense), net upon initial consolidation. The consolidated assets and liabilities as of December 31, 2023 and 2022 were immaterial. The results of operations were not significant for the years ended December 31, 2023 and 2022. The Company is not required to provide additional funding other than the contractually required amounts disclosed above. The creditors and beneficial holders of PharmaKrysto have no recourse to the general credit or assets of the Company.

MARKETABLE DEBT SECURITIES

MARKETABLE DEBT SECURITIES	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
MARKETABLE DEBT SECURITIES	MARKETABLE DEBT SECURITIES The Company's marketable debt securities as of December 31, 2023 and 2022 were composed of available-for-sale commercial paper and corporate and government debt securities. The primary objective of the Company’s investment portfolio is to preserve capital and liquidity while enhancing overall returns. The Company’s investment policy limits interest-bearing security investments to certain types of instruments issued by institutions with primarily investment grade credit ratings and places restrictions on maturities and concentration by asset class and issuer. Marketable debt securities consisted of the following ( in thousands ): As of December 31, 2023 2022 Marketable debt securities: Commercial paper $ 34,458 $ 123,647 Corporate debt securities 368,323 224,055 Securities of government-sponsored entities 105,894 40,855 Total available-for-sale marketable debt securities $ 508,675 $ 388,557 The following is a summary of short-term marketable debt securities classified as available-for-sale as of December 31, 2023 ( in thousands ): Remaining Contractual Maturity Amortized Cost Unrealized Gains Unrealized Losses Aggregate Estimated Fair Value Marketable debt securities: Commercial paper Less than 1 $ 34,450 $ 25 $ (17) $ 34,458 Corporate debt securities Less than 1 133,463 29 (408) 133,084 Securities of government-sponsored entities Less than 1 81,334 36 (274) 81,096 Total maturity less than 1 year 249,247 90 (699) 248,638 Corporate debt securities 1 to 2 233,969 1,444 (174) 235,239 Securities of government-sponsored entities 1 to 2 24,718 106 (26) 24,798 Total maturity 1 to 2 years 258,687 1,550 (200) 260,037 Total available-for-sale marketable debt securities $ 507,934 $ 1,640 $ (899) $ 508,675 The following is a summary of short-term marketable debt securities classified as available-for-sale as of December 31, 2022 ( in thousands ): Remaining Contractual Maturity Amortized Cost Unrealized Gains Unrealized Losses Aggregate Estimated Fair Value Marketable debt securities: Commercial paper Less than 1 $ 124,301 $ 2 $ (656) $ 123,647 Corporate debt securities Less than 1 155,841 — (1,355) 154,486 Securities of government-sponsored entities Less than 1 7,473 — (80) 7,393 Total maturity less than 1 year 287,615 2 (2,091) 285,526 Corporate debt securities 1 to 2 70,195 33 (659) 69,569 Securities of government-sponsored entities 1 to 2 33,702 6 (246) 33,462 Total maturity 1 to 2 years 103,897 39 (905) 103,031 Total available-for-sale marketable debt securities $ 391,512 $ 41 $ (2,996) $ 388,557 During 2023 and 2022, realized gains on marketable debt securities were immaterial. As of December 31, 2023 and December 31, 2022, the accrued interest receivable related to the Company's marketable debt securities was $4.6 million and $1.9 million, respectively, and was recorded in prepaid expenses and other current assets on the Consolidated Balance Sheets. The Company reviews the available-for-sale marketable debt securities for declines in fair value below the cost basis each quarter. For any security whose fair value is below its amortized cost basis, the Company first evaluates whether it intends to sell the impaired security, or will otherwise be more likely than not required to sell the security before recovery. If either are true, the amortized cost basis of the security is written down to its fair value at the reporting date. If neither circumstance holds true, the Company assesses whether any portion of the unrealized loss is a result of a credit loss. Any amount deemed to be attributable to credit loss is recognized in the income statement, with the amount of the loss limited to the difference between fair value and amortized cost and recorded as an allowance for credit losses. The portion of the unrealized loss related to factors other than credit losses is recognized in other comprehensive income (loss). The following is a summary of available-for-sale marketable debt securities in an unrealized loss position with no credit losses reported as of December 31, 2023 ( in thousands ): Less Than 12 Months 12 Months or Greater Total Description of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 24,798 $ 17 $ — $ — $ 24,798 $ 17 Corporate debt securities 140,802 405 28,775 177 169,577 582 Securities of government-sponsored entities 61,933 217 12,540 83 74,473 300 Total $ 227,533 $ 639 $ 41,315 $ 260 $ 268,848 $ 899 The following is a summary of available-for-sale marketable debt securities in an unrealized loss position with no credit losses reported as of December 31, 2022 ( in thousands ): Less Than 12 Months 12 Months or Greater Total Description of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 117,853 $ 656 $ — $ — $ 117,853 $ 656 Corporate debt securities 99,066 1,041 107,964 973 207,030 2,014 Securities of government-sponsored entities 31,402 263 4,456 63 35,858 326 Total $ 248,321 $ 1,960 $ 112,420 $ 1,036 $ 360,741 $ 2,996 As of December 31, 2023 and December 31, 2022, the amortized cost of the available-for-sale marketable debt securities in an unrealized loss position was $269.7 million and $363.7 million, respectively. As of December 31, 2023 and December 31, 2022, the Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost basis. The decrease in unrealized losses for the year ended December 31, 2023 was primarily due to fluctuations in short-term interest rates. The Company does not believe the unrealized losses incurred during the period are due to credit-related factors. The credit ratings of the securities held remain of the highest quality. Moreover, the Company continues to receive payments of interest and principal as they become due, and our expectation is that those payments will continue to be received timely. Factors unknown to us at this time may cause actual results to differ and require adjustments to the Company’s estimates and assumptions in the future.

CONVERTIBLE NOTES PAYABLE

CONVERTIBLE NOTES PAYABLE	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
CONVERTIBLE NOTES PAYABLE	CONVERTIBLE NOTES PAYABLE The composition of the Company’s convertible senior notes are as follows ( in thousands ): December 31, 2023 December 31, 2022 2.25% convertible senior notes due 2029 $ 316,250 $ 316,250 2.50% convertible senior notes due 2025 68,904 68,904 Unamortized debt issuance costs - 2.25% convertible senior notes due 2029 (7,348) (8,750) Unamortized debt issuance costs - 2.50% convertible senior notes due 2025 (543) (859) Total convertible senior notes, net of unamortized debt discount and debt issuance costs $ 377,263 $ 375,545 Convertible Senior Notes Due 2029 On March 11, 2022, the Company completed a registered underwritten public offering of $316.3 million aggregate principal amount of 2.25% Convertible Senior Notes due 2029 (“2029 Notes”), which includes $41.3 million aggregate principal amount of 2029 Notes sold pursuant to the full exercise of the underwriters’ option to purchase additional 2029 Notes. The Company issued the 2029 Notes under an indenture, dated as of September 10, 2018, as supplemented by the second supplemental indenture, dated as of March 11, 2022 (collectively, the “2029 Indenture”). The 2029 Notes will mature on March 1, 2029, unless earlier repurchased, redeemed, or converted. The 2029 Notes are senior unsecured obligations of the Company and bear interest at an annual rate of 2.25%, payable semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2022. The Company received net proceeds from the issuance of the 2029 Notes of $306.4 million, after deducting commissions and offering expenses of $9.9 million. At December 31, 2023, accrued interest on the 2029 Notes of $2.4 million is included in accrued expenses in the accompanying Consolidated Balance Sheets. The 2029 Notes comprise the Company’s senior, unsecured obligations and are (i) equal in right of payment with the Company’s existing and future senior, unsecured indebtedness; (ii) senior in right of payment to the Company’s existing and future indebtedness that is expressly subordinated to the 2029 Notes; (iii) effectively subordinated to the Company’s existing and future secured indebtedness, to the extent of the value of the collateral securing that indebtedness; and (iv) structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables. Holders may convert their 2029 Notes at their option only in the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2022 (and only during such calendar quarter), if the last reported sale price per share of the Company’s common stock for each of at least 20 trading days, whether or not consecutive, during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 130% of the conversion price on the applicable trading day; (2) during the five consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) if the trading price per $1,000 principal amount of 2029 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (3) upon the occurrence of certain corporate events or distributions of the Company’s common stock; (4) if the Company calls the 2029 Notes for redemption; and (5) at any time from, and including, December 1, 2028 until the close of business on the scheduled trading day immediately before the maturity date. The Company will settle conversions by paying or delivering, as applicable, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, based on the applicable conversion rate. The initial conversion rate for the 2029 Notes is 31.3740 shares of the Company’s common stock per $1,000 principal amount of 2029 Notes, which represents an initial conversion price of approximately $31.87 per share. If a “make-whole fundamental change” (as defined in the 2029 Indenture) occurs, then the Company will, in certain circumstances, increase the conversion rate for a specified period of time. The 2029 Notes will be redeemable, in whole or in part at the Company’s option at any time, and from time to time, on or after March 2, 2026 and, in the case of any partial redemption, on or before the 40th scheduled trading day before the maturity date, at a cash redemption price equal to the principal amount of the 2029 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date but only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on (1) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (2) the trading day immediately before the date the Company sends such notice. However, the Company may not redeem less than all of the outstanding 2029 Notes unless at least $100.0 million aggregate principal amount of 2029 Notes are outstanding and not called for redemption as of the time the Company sends the related redemption notice. In addition, calling any 2029 Note for redemption will constitute a make-whole fundamental change with respect to that 2029 Note, in which case the conversion rate applicable to the conversion of that 2029 Note will be increased in certain circumstances if it is converted after it is called for redemption. If a fundamental change (as defined in the 2029 Indenture) occurs, then, except as described in the 2029 Indenture, holders may require the Company to repurchase their 2029 Notes at a cash repurchase price equal to the principal amount of the 2029 Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date. In the event of conversion, holders would forgo all future interest payments, any unpaid accrued interest and the possibility of further stock price appreciation. Upon the receipt of conversion requests, the settlement of the 2029 Notes will be paid pursuant to the terms of the 2029 Indenture. In the event that all of the 2029 Notes are converted, the Company would be required to repay the principal amount and any conversion premium in any combination of cash and shares of its common stock at the Company’s option. In addition, calling the 2029 Notes for redemption will constitute a “make-whole fundamental change." The Company incurred approximately $9.9 million of debt issuance costs relating to the issuance of the 2029 Notes, which were recorded as a reduction to the 2029 Notes on the Consolidated Balance Sheets. The debt issuance costs are being amortized and recognized as additional interest expense over the expected life of the 2029 Notes using the effective interest method. We determined the expected life of the debt is equal to the seven-year term of the 2029 Notes. The effective interest rate on the 2029 Notes is 2.74%. Convertible Senior Notes Due 2025 On September 10, 2018, the Company completed a registered underwritten public offering of $276.0 million aggregate principal amount of 2.50% Convertible Senior Notes due 2025 ("2025 Notes"), and entered into a base indenture and supplemental indenture agreement ("2025 Indenture") with respect to the 2025 Notes. The 2025 Notes will mature on September 15, 2025, unless earlier repurchased, redeemed, or converted. The 2025 Notes are senior unsecured obligations of the Company and bear interest at an annual rate of 2.50%, payable semi-annually in arrears on March 15 and September 15 of each year, beginning on March 15, 2019. The net proceeds from the issuance of the 2025 Notes were approximately $267.2 million, after deducting commissions and the offering expenses of $8.8 million payable by the Company. At December 31, 2023, accrued interest of $0.5 million is included in accrued expenses in the accompanying Consolidated Balance Sheets. The 2025 Notes comprise the Company’s senior, unsecured obligations and are (i) equal in right of payment with the Company’s existing and future senior, unsecured indebtedness; (ii) senior in right of payment to the Company’s existing and future indebtedness that is expressly subordinated to the 2025 Notes; (iii) effectively subordinated to the Company’s existing and future secured indebtedness, to the extent of the value of the collateral securing that indebtedness; and (iv) structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables. Holders may convert their 2025 Notes at their option only in the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2018 (and only during such calendar quarter), if the last reported sale price per share of the Company’s common stock for each of at least 20 trading days, whether or not consecutive, during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 130% of the conversion price on the applicable trading day; (2) during the five consecutive business days immediately after any 10 consecutive trading day period (“measurement period”) if the trading price per $1,000 principal amount of 2025 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (3) upon the occurrence of certain corporate events or distributions on the Company’s common stock; (4) if the Company calls the 2025 Notes for redemption; and (5) at any time from, and including, May 15, 2025 until the close of business on the scheduled trading day immediately before the maturity date. The Company will settle conversions by paying or delivering, as applicable, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, based on the applicable conversion rate. The initial conversion rate for the 2025 Notes is 25.7739 shares of the Company’s common stock per $1,000 principal amount of 2025 Notes, which represents an initial conversion price of approximately $38.80 per share. If a “make-whole fundamental change” (as defined in the 2025 Indenture) occurs, then the Company will, in certain circumstances, increase the conversion rate for a specified period of time. The 2025 Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after September 15, 2022 and, in the case of any partial redemption, on or before the 40th scheduled trading day before the maturity date, at a cash redemption price equal to the principal amount of the 2025 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, but only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on each of at least 20 trading days during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice. If a fundamental change (as defined in the 2025 Indenture) occurs, then, subject to certain exceptions, holders may require the Company to repurchase their 2025 Notes at a cash repurchase price equal to the principal amount of the 2025 Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date. In the event of conversion, holders would forgo all future interest payments, any unpaid accrued interest and the possibility of further stock price appreciation. Upon the receipt of conversion requests, the settlement of the 2025 Notes will be paid pursuant to the terms of the 2025 Indenture. In the event that all of the 2025 Notes are converted, the Company would be required to repay the principal amount and any conversion premium in any combination of cash and shares of its common stock at the Company’s option. In addition, calling the 2025 Notes for redemption will constitute a “make-whole fundamental change." The Company incurred approximately $8.8 million of debt issuance costs relating to the issuance of the 2025 Notes, which were recorded as a reduction to the 2025 Notes on the Consolidated Balance Sheets. The debt issuance costs are being amortized and recognized as additional interest expense over the expected life of the 2025 Notes using the effective interest method. The Company determined the expected life of the debt is equal to the seven-year term of the 2025 Notes. The effective interest rate on the 2025 Notes is 2.98%. On March 11, 2022, the Company completed its repurchase of $207.1 million aggregate principal amount of 2025 Notes for cash, including accrued and unpaid interest, for a total of $213.8 million. This transaction involved a contemporaneous exchange of cash between the Company and holders of the 2025 Notes participating in the issuance of the 2029 Notes. Accordingly, we evaluated the transaction for modification or extinguishment accounting in accordance with ASC 470-50, Debt – Modifications and Extinguishments on a creditor-by creditor basis depending on whether the exchange was determined to have substantially different terms. The repurchase of the 2025 Notes and issuance of the 2029 Notes were deemed to have substantially different terms based on the present value of the cash flows or significant difference between the value of the conversion option immediately prior to and after the exchange. Therefore, the repurchase of the 2025 Notes was accounted for as a debt extinguishment. The Company recorded a $7.6 million loss on extinguishment of debt on its Consolidated Statements of Operations for the year ended December 31, 2022, which included the write-off of related deferred financing costs of $3.4 million. After giving effect to the repurchase, and as of December 31, 2023, the total remaining principal amount outstanding under the 2025 Notes was $68.9 million. The 2025 and 2029 Notes are accounted for in accordance with ASC 470-20, Debt with conversion and Other Options (“ASC 470-20”) and ASC 815-40, Contracts in Entity’s Own Equity (“ASC 815-40”). Under ASC 815-40, to qualify for equity classification (or nonbifurcation, if embedded) the instrument (or embedded feature) must be both (1) indexed to the issuer’s stock and (2) meet the requirements of equity classification guidance. Based upon the Company’s analysis, it was determined that the 2025 Notes and the 2029 Notes do not contain embedded features requiring recognition as derivatives and bifurcation, and therefore are measured at amortized cost and recorded as liabilities on the Consolidated Balance Sheets. The 2025 and 2029 Notes do not contain any financial or operating covenants or any restrictions on the payment of dividends, the issuance of other indebtedness or the issuance or repurchase of securities by the Company. There were no events of default for the 2025 Notes or 2029 Notes at December 31, 2023. The 2025 and 2029 Notes are classified on the Company's Consolidated Balance Sheets at December 31, 2023 as long-tern convertible debt. Interest Expense The following table sets forth total interest expense recognized related to the 2025 and 2029 Notes ( in thousands ): Year Ended December 31, 2023 2022 2021 Contractual interest expense $ 8,838 $ 8,433 $ 6,900 Amortization of debt discount — — 10,339 Amortization of debt issuance costs 1,718 1,622 903 Total interest expense for the 2025 and 2029 Notes $ 10,556 $ 10,055 $ 18,142

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below: Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The valuation techniques used to measure the fair value of the Company’s debt securities and all other financial instruments, all of which have counterparties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. Based on the fair value hierarchy, the Company classified marketable debt securities within Level 2. Financial instruments with carrying values approximating fair value include cash and cash equivalents, accounts receivable, and accounts payable, due to their short-term nature. As of December 31, 2023 and 2022, the fair value of the Company's 2.50% Convertible Senior Notes due 2025 was $58.3 million and $62.9 million, respectively. As of December 31, 2023 and 2022, the fair value of the Company's 2.25% Convertible Senior Notes due 2029, which were issued in 2022, was $212.1 million and $283.0 million, respectively. The fair values were estimated utilizing market quotations and are considered Level 2. The following table presents the Company’s assets, measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2023 (in thousands): As of December 31, 2023 Fair Value Hierarchy at December 31, 2023 Total carrying and estimated fair value Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets: Cash and Cash Equivalents $ 58,176 $ 58,176 $ — $ — Marketable debt securities, available-for-sale 508,675 — 508,675 — Total $ 566,851 $ 58,176 $ 508,675 $ — The following table presents the Company’s assets, measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2022 (in thousands): As of December 31, 2022 Fair Value Hierarchy at December 31, 2022 Total carrying and estimated fair value Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets: Cash and Cash Equivalents $ 61,688 $ 61,688 $ — $ — Marketable debt securities, available-for-sale 388,557 — 388,557 — Total $ 450,245 $ 61,688 $ 388,557 $ —

INTANGIBLE ASSETS

INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS	INTANGIBLE ASSETS Amortizable Intangible Assets Ligand License Agreement In 2012, the Company entered into an agreement with Ligand Pharmaceuticals, Inc. ("Ligand") for a worldwide sublicense to develop, manufacture and commercialize sparsentan (the “Ligand License Agreement”). As consideration for the license, the Company is required to make substantial payments upon the achievement of certain milestones, totaling up to $114.1 million. In March 2023, the Company capitalized a $23.0 million milestone payment to Ligand (and Bristol-Myers Squibb Company ("BMS")) that was triggered upon the accelerated approval of FILSPARI in February 2023. Pursuant to the Ligand License Agreement, the Company is obligated to pay to Ligand (and BMS) an escalating royalty between 15% and 17% of net sales of sparsentan, with payments due quarterly. The Company began incurring costs associated with such royalties following the February 2023 approval of FILSPARI (sparsentan). For the year ended December 31, 2023, the Company capitalized $4.4 million to intangible assets for royalties owed on net sales of FILSPARI. The cost of the $23.0 million milestone payment and royalty payments are being amortized to selling, general and administration on a straight-line basis through April 30, 2033 Thiola License Agreement The Company entered into a license agreement with Mission Pharmacal in 2014, in which the Company obtained an exclusive, royalty-bearing license to market, sell and commercialize Thiola (tiopronin) in the United States and Canada, and a non-exclusive license to use know-how relating to Thiola to the extent necessary to market Thiola. The initial term of the license is 10 years and will automatically renew thereafter for periods of one year. The acquisition of the Thiola license qualified as an asset acquisition under the principles of ASC 805 in effect at the time of acquisition. The license agreement requires the Company to make royalty payments based on net sales of Thiola. The liability for royalties in excess of the annual contractual minimum is recognized in the period in which the royalties become probable and estimable, which is typically in the period corresponding with the respective sales. The Company records an offsetting increase to the cost basis of the asset under the cost accumulation model. The additional cost basis is subsequently amortized over the remaining life of the license agreement. The Company paid Mission an up-front license fee of $3.0 million and during the term of the agreement will pay the greater of $2.0 million, representing the guaranteed minimum royalty, or 20% of the Company’s net sales of Thiola during each calendar year. In November 2017, the Company amended its agreement with Mission to extend the term of the current exclusive U.S. and Canada licensing agreement by an additional five years, to 2029. The royalty rate and guaranteed minimum payment were also extended through the new agreement term. Upon execution of the amendment, the Company capitalized an additional $5.9 million in intangible assets and recorded a guaranteed minimum liability for the same amount. In November 2018, the Company amended its agreement with Mission to remove all territorial restrictions on our license. As consideration for the expanded territory, the Company paid an up-front fee of $0.3 million and will pay the greater of $0.1 million, representing the guaranteed minimum, or 20% of the Company's net sales of Thiola generated outside of the United States during each calendar year. Upon execution of the amendment, the Company capitalized an additional $1.0 million in intangible assets and recorded a guaranteed minimum liability of $0.7 million related to this amendment. The present value of guaranteed minimum royalties payable using a discount rate ranging from approximately 7% to 11% based on the Company’s then borrowing rate is $9.7 million and $11.1 million as of December 31, 2023 and 2022, respectively. As of December 31, 2023, the guaranteed minimum royalty current and long-term liability was approximately $2.1 million and $7.6 million, respectively, and is recorded as Other Liability in the Consolidated Balance Sheets. As of December 31, 2022, the guaranteed minimum royalty current and long-term liability was approximately $2.1 million and $9.0 million, respectively, and is recorded as Other Liability in the Consolidated Balance Sheets. The Company has capitalized $155.6 million related to the Thiola intangible asset which consists of the up-front license fee, professional fees, present value of the guaranteed minimum royalties and any additional payments through December 31, 2023 in excess of minimum royalties. In 2023 the Company added $16.2 million to the intangible asset related to royalties in excess of the minimum. Consistent with all prior periods since Thiola was acquired, the Company has not accrued any liability for royalties in excess of the annual contractual minimum at December 31, 2023, as such royalties are not yet probable and estimable. Amortizable intangible assets as of December 31, 2023 ( in thousands ): Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Thiola license 12 $ 155,589 $ (77,311) $ 78,278 Ligand license 11 27,448 (2,036) 25,412 Total amortizable intangible assets $ 183,037 $ (79,347) $ 103,690 Amortizable intangible assets as of December 31, 2022 ( in thousands ): Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Thiola license 12 $ 139,383 $ (50,324) $ 89,059 Ligand license 11 19,400 (12,139) 7,261 Total amortizable intangible assets $ 158,783 $ (62,463) $ 96,320 The following table summarizes amortization expense for the year ended December 31, 2023, 2022 and 2021 ( in thousands ): 2023 2022 2021 Selling, general and administrative $ 29,021 $ 12,339 $ 9,888 Research and development 7,261 6,264 1,158 Total amortization expense $ 36,282 $ 18,603 $ 11,046 As of December 31, 2023, amortization expense for the next five years and thereafter is expected to be as follows ( in thousands ): 2024 $ 37,625 2025 40,709 2026 8,347 2027 2,722 2028 2,729 Thereafter 11,558 Total $ 103,690 Goodwill As of December 31, 2023 and 2022, the Company had goodwill of $0.8 million.

ACCRUED EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consist of the following at December 31, 2023 and 2022 ( in thousands ): 2023 2022 Compensation related costs $ 29,908 $ 35,267 Research and development 26,006 26,070 Sales discounts, rebates, and allowances 13,730 13,486 Transition services accrual 12,282 — Accrued restructuring costs 11,421 — Selling, general and administrative 7,190 8,791 Accrued royalties 6,991 7,755 Miscellaneous accrued 11,463 4,373 Total accrued expenses $ 118,991 $ 95,742

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Commitments Certain of the Company's contractual arrangements with contract manufacturing organizations ("CMOs") require binding forecasts or commitments to purchase minimum amounts for the manufacture of drug product supply, which may be material to the Company's financial statements. Contingencies In November 2020, the Company completed the acquisition of Orphan Technologies Limited (“Orphan”), including Orphan’s rare metabolic disorder drug pegtibatinase. The Company acquired Orphan by purchasing all of the outstanding shares. Under the Agreement, the Company has also agreed to make contingent cash payments up to an aggregate of $427.0 million based on the achievement of certain development, regulatory and commercialization events as set forth in the Agreement, as well as additional tiered mid-single digit royalty payments based upon future net sales of any pegtibatinase products in the US and Europe, subject to certain reductions as set forth in the Agreement, and a contingent payment in the event a pediatric rare disease voucher for any pegtibatinase product is granted. In accordance with ASC 450, contingent cash payments will be accrued for when it is probable that a liability has been incurred and the amount can be reasonably estimated. As of December 31, 2023, no contingent cash payments have been accrued. The Company anticipates that it may achieve certain milestones with both FILSPARI and pegtibatinase that will result in the Company making net payments of approximately $50.0 million in the next 12 months. Legal Proceedings From time to time in the normal course of business, the Company is subject to various legal matters such as threatened or pending claims or litigation. Although the results of claims and litigation cannot be predicted with certainty, the Company does not believe it is a party to any claim or litigation in which the outcome, if determined adversely to it, would individually or in the aggregate be reasonably expected to have a material adverse effect on its results of operations or financial condition.

STOCKHOLDERS_ EQUITY

STOCKHOLDERS’ EQUITY	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
STOCKHOLDERS’ EQUITY	STOCKHOLDERS’ EQUITY Common Stock The Company is currently authorized to issue up to 200,000,000 shares of $0.0001 par value common stock. All issued shares of common stock are entitled to vote on a 1 share/1 vote basis. Preferred Stock The Company is currently authorized to issue up to 20,000,000 shares of $0.0001 par value preferred stock, of which 1,000 shares are designated Class "A" Preferred shares. Class A Preferred Shares are not entitled to interest, have certain liquidation preferences, special voting rights and other provisions. No preferred stock has been issued to date. 2018 Equity Incentive Plan The Company's 2018 Equity Incentive Plan (the "2018 Plan") is the successor to and continuation of the Company's 2015 Equity Incentive Plan (the "2015 Plan") and the Company's 2014 Equity Incentive Plan (the "2014 Plan", and together with the 2015 Plan, the "Prior Plans"). Unallocated shares under the Prior Plans are no longer available for issuance under the Prior Plans, and have instead been added to the shares available for issuance under the 2018 Plan. The 2018 Plan, as amended, and including the unallocated shares of the Prior Plans, provides for a total of 15.7 million shares to be issued, plus the Prior Plans' returning shares, if any, which become available for grant under the 2018 Plan from time to time. Options issued under the 2018 Plan will generally expire ten years from the date of grant and vest over a four-year period. As of December 31, 2023, there were approximately 4.5 million shares reserved for future issuance under the 2018 Plan. 2017 Employee Stock Purchase Plan The 2017 Employee Stock Purchase Plan ("2017 ESPP") originated with 380,000 shares of common stock available for issuance. Beginning on January 1, 2018, and ending on (and including) January 1, 2026, the number of shares of common stock available for issuance under the 2017 ESPP may increase by an amount equal to the lesser of (i) one percent (1%) of the total number of shares of common stock outstanding on December 31st of the preceding calendar year or (ii) 300,000 shares of common stock. Substantially all employees are eligible to participate in the 2017 ESPP and, through payroll deductions, can purchase shares on established dates semi-annually. The purchase price per share sold pursuant to the 2017 ESPP will be the lower of (i) 85% of the fair market value of common stock on the first day of the offering period or (ii) 85% of the fair market value on the purchase date. Each offering period will span up to six months. Purchases may be up to 15% of qualified compensation, with an annual limit of $25,000. The 2017 ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code. As of December 31, 2023, there were approximately 2,180,000 shares authorized and 1,100,657 shares reserved for future issuance under the 2017 ESPP. Stock Options The fair values of stock option grants during the years ended December 31, 2023, 2022 and 2021 were calculated on the date of grant using the Black-Scholes option pricing model. Compensation expense is recognized over the period of service, generally the vesting period. The following weighted average assumptions were used in the Black-Scholes options pricing model to estimate the fair value of stock options for the specified reporting periods: Year Ended December 31, 2023 2022 2021 Risk free rate 3.9 % 1.7 % 0.6 % Expected volatility 50 % 50 % 59 % Expected life (in years) 6.4 6.4 6.4 Expected dividend yield — — — The risk-free interest rate was based on rates established by the Federal Reserve. The Company’s expected volatility was based on analysis of the Company’s historical volatility. The expected life of the Company’s options was determined using the Company's historical exercise activity. The dividend yield is based upon the fact that the Company has not historically paid dividends and does not expect to pay dividends in the foreseeable future. The following table summarizes our stock option activity and related information for the year ended December 31, 2023: Weighted Average Shares Underlying Exercise Remaining Aggregate Outstanding at December 31, 2022 9,932,422 $ 21.56 5.79 $ 24,658 Granted 1,157,750 21.69 — — Forfeited and expired (652,156) 24.98 — — Exercised (226,663) 14.30 — 1,422 Outstanding at December 31, 2023 10,211,353 $ 21.52 4.91 $ — Vested and expected to vest at December 31, 2023 10,211,353 $ 21.52 4.88 $ — The aggregate intrinsic value of stock options exercised in the years ended December 31, 2023, 2022 and 2021 was $1.4 million, $5.1 million, and $7.5 million, respectively. The following table summarizes our stock options exercisable at December 31, 2023, 2022 and 2021: Weighted Average Shares Underlying Exercise Remaining Aggregate Exercisable at December 31, 2021 6,011,349 $ 19.34 5.16 $ 71,063 Exercisable at December 31, 2022 6,999,669 $ 20.22 4.62 $ 21,806 Exercisable at December 31, 2023 7,942,964 $ 20.85 3.95 $ — The weighted average grant date fair value of options granted was $11.66, $13.45, and $14.00 during the years ended December 31, 2023, 2022 and 2021, respectively. The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the closing price of the Company’s common stock of $8.99, $21.03 and $31.04 as of December 31, 2023, 2022 and 2021, respectively. Unrecognized compensation cost associated with unvested stock options amounts to $24.1 million as of December 31, 2023, which will be expensed over a weighted average remaining vesting period of 2.3 years. In connection with the retirement of the Company's former Chief Financial Officer, the Board of Directors approved a modification to extend the deadline to exercise each stock option held to the earlier of three months following the last vesting date or the original expiration date of the option, and to continue vesting on the original schedule of any underlying unvested stock options and restricted stock units. The modification resulted in incremental compensation cost of $2.6 million for the year ended December 31, 2023. Restricted Stock Units As of December 31, 2023, there was approximately $46.8 million of unrecognized compensation cost related to restricted stock units ("RSUs") granted. This amount is expected to be recognized over a weighted average period of 2.5 years. The following table summarizes our restricted stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 2,343,709 $ 24.65 Granted 1,907,542 21.20 Vested (803,113) 23.30 Forfeited/cancelled (574,092) 23.48 Unvested December 31, 2023 2,874,046 $ 22.97 The fair value of restricted stock units vested for the years ended December 31, 2023, 2022 and 2021 was $18.7 million, $11.5 million, and $7.4 million, respectively. The weighted average grant date fair value for stock awards granted during the years ended December 31, 2023, 2022 and 2021 was $23.30, $21.21, and $18.08, respectively. Performance-based Stock Units Performance-based stock units ("PSUs") are subject to vest only if certain specified criteria are achieved. As of December 31, 2023, there was approximately $2.0 million of unrecognized compensation cost related to PSUs granted and deemed probable of vesting. This amount is expected to be recognized over a weighted average period of 0.9 years. The following table summarizes our performance-based stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 157,048 $ 25.24 Granted 66,250 22.40 Vested (16,500) 15.46 Forfeited/cancelled (31,340) 22.31 Unvested December 31, 2023 175,458 $ 25.61 The fair value of PSUs vested for the years ended December 31, 2023, 2022 and 2021 was $0.3 million, $0.4 million, and $1.8 million, respectively. The weighted average grant date fair value for performance-based stock awards granted during the years ended December 31, 2023, 2022 and 2021 was $15.46, $25.26, and $15.46, respectively. Share Based Compensation Total non-cash stock-based compensation expense consisted of the following for the years ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Selling, general and administrative expenses $ 27,111 $ 24,368 $ 17,009 Research and development expenses 17,135 13,775 12,557 Total stock-based compensation expense $ 44,246 $ 38,143 $ 29,566 Underwritten Public Offering of Common Stock In February 2023, the Company sold an aggregate of approximately 9.7 million shares of its common stock and pre-funded warrants to purchase 1.25 million shares of its common stock in an underwritten public offering, at a price to the public of $21.00 per share of common stock and $20.9999 per pre-funded warrant. The pre-funded warrants are exercisable immediately, subject to certain beneficial ownership limitations which can be modified by the respective holders with at least 61 days' notice, and are exercisable for one share of the Company's common stock. The exercise price of each pre-funded warrant is $0.0001 per share of common stock. The net proceeds to the Company from the offering, after deducting the underwriting discounts and offering expenses, were approximately $215.8 million. The pre-funded warrants were classified as a component of permanent stockholders' equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company's common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return. The Company valued the pre-funded warrants at issuance, concluding that their sale price approximated their fair value, and allocated the aggregate net proceeds from the sale proportionately to the common stock and prefunded warrants, including approximately $24.6 million allocated to the pre-funded warrants and recorded as a component of additional paid-in capital. In February 2021, the Company sold an aggregate of 7.5 million shares of its common stock in an underwritten public offering, at a price of $26.75 per share. The net proceeds to the Company from the offering, after deducting the underwriting discounts and offering expenses, were $189.3 million. At-the-Market Equity Offering In February 2020, the Company entered into an Open Market Sale Agreement ("ATM Agreement") with Jefferies LLC, as agent (“Jefferies”), pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Of the $100.0 million originally authorized for sale under the ATM Agreement, approximately $28.6 million were sold under the Company's prior registration statement on Form S-3 (Registration Statement No. 333-227182). An additional $51.9 million were sold under the Company's effective registration statement on Form S-3 (Registration Statement No. 333-259311), which included $20.1 million in the year ended December 31, 2022. The Company did not sell any shares under the ATM Agreement during the year ended December 31, 2023. As of December 31, 2023, an aggregate amount of $19.5 million remained eligible for sale under the ATM Agreement.

NET LOSS PER COMMON SHARE

NET LOSS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
NET LOSS PER COMMON SHARE	NET LOSS PER COMMON SHARE Basic and diluted net income (loss) per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period. In accordance with ASC 260, Earnings per Share, if a company had a discontinued operation, the company uses income from continuing operations, adjusted for preferred dividend and similar adjustments, as its control number to determine whether potential common shares are dilutive. As discussed in Note 15, as part of its February 2023 underwritten public offering, the Company issued and sold pre-funded warrants to purchase 1.25 million shares of its common stock at a price to the public of $20.9999 per pre-funded warrant. The pre-funded warrants are exercisable immediately and are exercisable for one share of the Company's common stock. The exercise price of each pre-funded warrant is $0.0001 per share of common stock. Since the $0.0001 price per share represents little consideration and is non-substantive in relation to the $20.9999 price per pre-funded warrant and the $21.00 price per share of the common stock offered to the public, and as the warrants are immediately exercisable with no further vesting conditions or contingencies associated with them, the shares underlying the warrants are therefore included in the calculation of basic net loss per common share. The Company’s potentially dilutive shares, which include outstanding stock options, restricted stock units, performance-based stock units, and shares issuable upon conversion of the 2025 Notes and 2029 Notes, are considered to be common stock equivalents and are not included in the calculation of diluted net loss per share because their effect is anti-dilutive. Basic and diluted net loss per share is calculated as follows (net loss amounts are stated in thousands) : For the year ended December 31, 2023 2022 2021 Shares Net (loss) income EPS Shares Net (loss) income EPS Shares Net (loss) income EPS Continuing operations 74,267,418 $ (376,333) $ (5.07) 63,758,515 $ (331,468) $ (5.20) 59,832,287 $ (217,292) $ (3.63) Discontinued operations 74,267,418 $ 264,934 $ 3.57 63,758,515 $ 52,986 $ 0.83 59,832,287 $ 37,201 $ 0.62 Basic and diluted loss per share 74,267,418 $ (111,399) $ (1.50) 63,758,515 $ (278,482) $ (4.37) 59,832,287 $ (180,091) $ (3.01) For the years ended December 31, 2023, 2022 and 2021, the following weighted-average number of common stock equivalents were excluded because they were anti-dilutive: For the year ended December 31, 2023 2022 2021 Convertible debt 11,697,952 10,869,000 7,113,402 Options 10,555,550 10,041,249 9,214,188 Restricted stock units and performance-based stock units 3,417,245 2,175,100 1,569,470 Total anti-dilutive shares 25,670,747 23,085,349 17,897,060

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES For financial reporting purposes, net loss from continuing operations before income taxes includes the following components ( in thousands ): Year Ended December 31, 2023 2022 2021 United States $ (293,283) $ (268,887) $ (161,333) Foreign (82,827) (62,268) (55,550) Total $ (376,110) $ (331,155) $ (216,883) The components of the provision for income taxes, in the Consolidated Statements of Operations are as follows ( in thousands ): 2023 2022 2021 Current Federal $ — $ — $ — State 223 314 412 Foreign — (1) (3) 223 313 409 Deferred Federal — — — State — — — — — — Total tax provision $ 223 $ 313 $ 409 The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate expressed as a percentage of loss before income taxes: 2023 2022 2021 Statutory rate - federal (21.00) % (21.00) % (21.00) % State taxes, net of federal benefit (3.19) % (3.62) % (2.92) % Foreign rate differential 1.29 % 0.81 % 2.72 % Nondeductible executive compensation 1.50 % 0.41 % 0.40 % Excess tax benefits associated with share-based awards 0.68 % (0.17) % 0.15 % Other permanent differences 0.37 % 0.17 % 0.12 % Tax credits (1.13) % (5.29) % (8.65) % Return to provision adjustments and other true-ups 4.19 % (0.17) % 2.00 % Adoption of ASU 2020-06 — % (3.54) % — % Other 0.57 % — % 0.18 % Change in valuation allowance 16.78 % 32.49 % 27.19 % Income tax provision (benefit) 0.06 % 0.09 % 0.19 % The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022 are as follows ( in thousands ): 2023 2022 Deferred Tax Assets: Net operating loss $ 81,531 $ 49,811 Research and development and other tax credits 77,555 91,052 Capitalized research and development 39,907 36,442 Contingent consideration — 18,124 Other accrued expenses 13,187 13,247 Stock based compensation 21,607 22,936 Charitable contributions 6,110 4,781 Intangible assets greater than book 47,731 51,391 Interest expense limitation 1,679 4,346 Operating lease liabilities 6,812 8,018 Tax basis depreciation greater than book depreciation 292 105 Difference in basis of loan costs 62 15 296,473 300,268 Deferred Tax Liabilities: Operating lease right of use assets (5,595) (6,658) Prepaid assets (198) (206) (5,793) (6,864) Net deferred tax assets before valuation allowance 290,680 293,404 Valuation allowance (290,680) (293,404) Total deferred tax assets $ — $ — The Company has established a full valuation allowance against its U.S. federal, state, and foreign deferred tax assets due to the uncertainty surrounding the realization of such assets in future periods. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which temporary differences become deductible. Management considers the scheduled reversal of deferred liabilities and tax planning strategies in making this assessment and evaluates the recoverability of the deferred tax assets as of each reporting date. At such time as it is determined that it is more likely than not that deferred assets are realizable, the valuation allowance will be reduced accordingly and recorded as a tax benefit. The Company has recorded a valuation allowance of $290.7 million as of December 31, 2023 to reflect the estimated amount of deferred tax assets that may not be realized. The Company decreased its valuation allowance by $2.7 million for the year ended December 31, 2023, compared to a $95.1 million increase for the year ended December 31, 2022. As of December 31, 2023, the Company had available unused U.S. federal and state net operating loss (“NOL”) carryforwards of $154.3 million and $208.4 million, respectively, all of which are fully offset by a valuation allowance. Additionally, the Company had an interest expense limitation carryforward of $8.0 million that is fully offset by a valuation allowance. The federal NOL and interest expense limitation carryforward have an indefinite life. The state NOL carryforwards will begin to expire in 2024 unless previously utilized, except for $39.8 million of the state net operating losses that have an indefinite carryforward period. In addition, at December 31, 2023, the Company had federal orphan drug tax credit carryforwards of $86.8 million that begin to expire in 2035 unless utilized, federal research and development tax credit carryforwards of $4.8 million that begin to expire in 2033 unless utilized, state research and development tax credit carryforwards of $8.0 million that begin to expire in 2030 unless utilized and $1.3 million that have an indefinite carryforward period, and California Competes tax credit carryforwards of $2.0 million that begin to expire in 2024. Pursuant to Internal Revenue Code Sections 382 and 383, use of the Company’s federal net operating loss and credit carryforwards may be limited upon a cumulative change in ownership of more than 50% within a three-year period. The Company completed a study to analyze whether any ownership changes had occurred through March 31, 2023, and determined no ownership changes occurred. The Company is in the process of updating its analysis of owner shifts to determine whether an ownership change occurred since March 31, 2023. Any change in ownership should not impact the utilization of tax attributes for the year ended December 31, 2023, and due to the Company’s full valuation allowance any subsequent ownership changes will not impact the Company’s effective tax rate. As of December 31, 2023, the Company had Irish NOL carryforwards of $16.1 million which are fully offset by a valuation allowance and have an indefinite life. The Company also had Swiss NOL carryforwards of $251.1 million which are fully offset by a valuation allowance and begin to expire in 2024, as well as Federal Act on Tax Reform and AHV Financing (“TRAF”) cantonal tax benefits of $526.2 million which expire in 2029. The Company accounts for uncertain tax benefits in accordance with the provisions of ASC 740-10 of the Accounting for Uncertainty in Income Taxes . As of December 31, 2023, the Company had $22.9 million in unrecognized tax benefits, all of which are related to orphan drug and research and development tax credits and were recorded as a reduction to the deferred tax assets with a corresponding reduction in the Company’s valuation allowance of $22.9 million. To the extent unrecognized tax benefits are recognized at a time when a valuation allowance does not exist, the recognition of the $22.9 million tax benefit would reduce the effective tax rate. The Company does not anticipate that the amount of unrecognized tax benefits as of December 31, 2023 will change materially within the following 12 months. A reconciliation of the Company's unrecognized tax benefits for the years 2023 and 2022 is provided in the following table ( in thousands ): 2023 2022 Balance as of January 1: $ 11,490 $ 7,825 Increase in current period positions 4,871 2,056 Increase in prior period positions 7,383 1,919 Decrease in prior period positions (838) — Decrease due to settlements with tax authorities — (310) Balance as of December 31: $ 22,906 $ 11,490 The Company files income tax returns in the U.S. federal jurisdiction, various state and local, and foreign jurisdictions. With few exceptions related to the carryforward of unutilized tax attributes, the Company’s income tax returns are open to examination by federal authorities for the years ended December 31, 2019, and forward, and for state authorities, for the years ended December 31, 2014, and forward. The Company's Swiss income tax returns are open to examination for the years ended December 31, 2018, and forward and the Company's Irish tax returns are open to examination for the years ended December 31, 2019, and forward.

EQUITY OFFERINGS

EQUITY OFFERINGS	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
EQUITY OFFERINGS	STOCKHOLDERS’ EQUITY Common Stock The Company is currently authorized to issue up to 200,000,000 shares of $0.0001 par value common stock. All issued shares of common stock are entitled to vote on a 1 share/1 vote basis. Preferred Stock The Company is currently authorized to issue up to 20,000,000 shares of $0.0001 par value preferred stock, of which 1,000 shares are designated Class "A" Preferred shares. Class A Preferred Shares are not entitled to interest, have certain liquidation preferences, special voting rights and other provisions. No preferred stock has been issued to date. 2018 Equity Incentive Plan The Company's 2018 Equity Incentive Plan (the "2018 Plan") is the successor to and continuation of the Company's 2015 Equity Incentive Plan (the "2015 Plan") and the Company's 2014 Equity Incentive Plan (the "2014 Plan", and together with the 2015 Plan, the "Prior Plans"). Unallocated shares under the Prior Plans are no longer available for issuance under the Prior Plans, and have instead been added to the shares available for issuance under the 2018 Plan. The 2018 Plan, as amended, and including the unallocated shares of the Prior Plans, provides for a total of 15.7 million shares to be issued, plus the Prior Plans' returning shares, if any, which become available for grant under the 2018 Plan from time to time. Options issued under the 2018 Plan will generally expire ten years from the date of grant and vest over a four-year period. As of December 31, 2023, there were approximately 4.5 million shares reserved for future issuance under the 2018 Plan. 2017 Employee Stock Purchase Plan The 2017 Employee Stock Purchase Plan ("2017 ESPP") originated with 380,000 shares of common stock available for issuance. Beginning on January 1, 2018, and ending on (and including) January 1, 2026, the number of shares of common stock available for issuance under the 2017 ESPP may increase by an amount equal to the lesser of (i) one percent (1%) of the total number of shares of common stock outstanding on December 31st of the preceding calendar year or (ii) 300,000 shares of common stock. Substantially all employees are eligible to participate in the 2017 ESPP and, through payroll deductions, can purchase shares on established dates semi-annually. The purchase price per share sold pursuant to the 2017 ESPP will be the lower of (i) 85% of the fair market value of common stock on the first day of the offering period or (ii) 85% of the fair market value on the purchase date. Each offering period will span up to six months. Purchases may be up to 15% of qualified compensation, with an annual limit of $25,000. The 2017 ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code. As of December 31, 2023, there were approximately 2,180,000 shares authorized and 1,100,657 shares reserved for future issuance under the 2017 ESPP. Stock Options The fair values of stock option grants during the years ended December 31, 2023, 2022 and 2021 were calculated on the date of grant using the Black-Scholes option pricing model. Compensation expense is recognized over the period of service, generally the vesting period. The following weighted average assumptions were used in the Black-Scholes options pricing model to estimate the fair value of stock options for the specified reporting periods: Year Ended December 31, 2023 2022 2021 Risk free rate 3.9 % 1.7 % 0.6 % Expected volatility 50 % 50 % 59 % Expected life (in years) 6.4 6.4 6.4 Expected dividend yield — — — The risk-free interest rate was based on rates established by the Federal Reserve. The Company’s expected volatility was based on analysis of the Company’s historical volatility. The expected life of the Company’s options was determined using the Company's historical exercise activity. The dividend yield is based upon the fact that the Company has not historically paid dividends and does not expect to pay dividends in the foreseeable future. The following table summarizes our stock option activity and related information for the year ended December 31, 2023: Weighted Average Shares Underlying Exercise Remaining Aggregate Outstanding at December 31, 2022 9,932,422 $ 21.56 5.79 $ 24,658 Granted 1,157,750 21.69 — — Forfeited and expired (652,156) 24.98 — — Exercised (226,663) 14.30 — 1,422 Outstanding at December 31, 2023 10,211,353 $ 21.52 4.91 $ — Vested and expected to vest at December 31, 2023 10,211,353 $ 21.52 4.88 $ — The aggregate intrinsic value of stock options exercised in the years ended December 31, 2023, 2022 and 2021 was $1.4 million, $5.1 million, and $7.5 million, respectively. The following table summarizes our stock options exercisable at December 31, 2023, 2022 and 2021: Weighted Average Shares Underlying Exercise Remaining Aggregate Exercisable at December 31, 2021 6,011,349 $ 19.34 5.16 $ 71,063 Exercisable at December 31, 2022 6,999,669 $ 20.22 4.62 $ 21,806 Exercisable at December 31, 2023 7,942,964 $ 20.85 3.95 $ — The weighted average grant date fair value of options granted was $11.66, $13.45, and $14.00 during the years ended December 31, 2023, 2022 and 2021, respectively. The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the closing price of the Company’s common stock of $8.99, $21.03 and $31.04 as of December 31, 2023, 2022 and 2021, respectively. Unrecognized compensation cost associated with unvested stock options amounts to $24.1 million as of December 31, 2023, which will be expensed over a weighted average remaining vesting period of 2.3 years. In connection with the retirement of the Company's former Chief Financial Officer, the Board of Directors approved a modification to extend the deadline to exercise each stock option held to the earlier of three months following the last vesting date or the original expiration date of the option, and to continue vesting on the original schedule of any underlying unvested stock options and restricted stock units. The modification resulted in incremental compensation cost of $2.6 million for the year ended December 31, 2023. Restricted Stock Units As of December 31, 2023, there was approximately $46.8 million of unrecognized compensation cost related to restricted stock units ("RSUs") granted. This amount is expected to be recognized over a weighted average period of 2.5 years. The following table summarizes our restricted stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 2,343,709 $ 24.65 Granted 1,907,542 21.20 Vested (803,113) 23.30 Forfeited/cancelled (574,092) 23.48 Unvested December 31, 2023 2,874,046 $ 22.97 The fair value of restricted stock units vested for the years ended December 31, 2023, 2022 and 2021 was $18.7 million, $11.5 million, and $7.4 million, respectively. The weighted average grant date fair value for stock awards granted during the years ended December 31, 2023, 2022 and 2021 was $23.30, $21.21, and $18.08, respectively. Performance-based Stock Units Performance-based stock units ("PSUs") are subject to vest only if certain specified criteria are achieved. As of December 31, 2023, there was approximately $2.0 million of unrecognized compensation cost related to PSUs granted and deemed probable of vesting. This amount is expected to be recognized over a weighted average period of 0.9 years. The following table summarizes our performance-based stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 157,048 $ 25.24 Granted 66,250 22.40 Vested (16,500) 15.46 Forfeited/cancelled (31,340) 22.31 Unvested December 31, 2023 175,458 $ 25.61 The fair value of PSUs vested for the years ended December 31, 2023, 2022 and 2021 was $0.3 million, $0.4 million, and $1.8 million, respectively. The weighted average grant date fair value for performance-based stock awards granted during the years ended December 31, 2023, 2022 and 2021 was $15.46, $25.26, and $15.46, respectively. Share Based Compensation Total non-cash stock-based compensation expense consisted of the following for the years ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Selling, general and administrative expenses $ 27,111 $ 24,368 $ 17,009 Research and development expenses 17,135 13,775 12,557 Total stock-based compensation expense $ 44,246 $ 38,143 $ 29,566 Underwritten Public Offering of Common Stock In February 2023, the Company sold an aggregate of approximately 9.7 million shares of its common stock and pre-funded warrants to purchase 1.25 million shares of its common stock in an underwritten public offering, at a price to the public of $21.00 per share of common stock and $20.9999 per pre-funded warrant. The pre-funded warrants are exercisable immediately, subject to certain beneficial ownership limitations which can be modified by the respective holders with at least 61 days' notice, and are exercisable for one share of the Company's common stock. The exercise price of each pre-funded warrant is $0.0001 per share of common stock. The net proceeds to the Company from the offering, after deducting the underwriting discounts and offering expenses, were approximately $215.8 million. The pre-funded warrants were classified as a component of permanent stockholders' equity within additional paid-in capital and were recorded at the issuance date using a relative fair value allocation method. The pre-funded warrants are equity classified because they (i) are freestanding financial instruments that are legally detachable and separately exercisable from the equity instruments, (ii) are immediately exercisable, (iii) do not embody an obligation for the Company to repurchase its shares, (iv) permit the holders to receive a fixed number of shares of common stock upon exercise, (v) are indexed to the Company's common stock and (vi) meet the equity classification criteria. In addition, such pre-funded warrants do not provide any guarantee of value or return. The Company valued the pre-funded warrants at issuance, concluding that their sale price approximated their fair value, and allocated the aggregate net proceeds from the sale proportionately to the common stock and prefunded warrants, including approximately $24.6 million allocated to the pre-funded warrants and recorded as a component of additional paid-in capital. In February 2021, the Company sold an aggregate of 7.5 million shares of its common stock in an underwritten public offering, at a price of $26.75 per share. The net proceeds to the Company from the offering, after deducting the underwriting discounts and offering expenses, were $189.3 million. At-the-Market Equity Offering In February 2020, the Company entered into an Open Market Sale Agreement ("ATM Agreement") with Jefferies LLC, as agent (“Jefferies”), pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Of the $100.0 million originally authorized for sale under the ATM Agreement, approximately $28.6 million were sold under the Company's prior registration statement on Form S-3 (Registration Statement No. 333-227182). An additional $51.9 million were sold under the Company's effective registration statement on Form S-3 (Registration Statement No. 333-259311), which included $20.1 million in the year ended December 31, 2022. The Company did not sell any shares under the ATM Agreement during the year ended December 31, 2023. As of December 31, 2023, an aggregate amount of $19.5 million remained eligible for sale under the ATM Agreement.

RETIREMENT PLAN

RETIREMENT PLAN	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
RETIREMENT PLAN	RETIREMENT PLAN 401(k) Savings Plan The Company has a 401(k) defined contribution savings plan for the benefit of all eligible employees. Employer matching contributions were $2.7 million, $2.1 million, and $1.3 million for the years ended December 31, 2023, 2022 and 2021, respectively. Switzerland Defined Benefit Plan The Company maintains a defined benefit pension plan covering employees of its Swiss subsidiary, Travere Therapeutics Switzerland GmbH (the "Swiss Plan"). The Swiss Plan is a government-mandated retirement fund that provides employees with a minimum benefit. Employer and employee contributions are made to the Swiss Plan based on various percentages of participants' salaries and wages that vary according to the participants' age and other factors. As of December 31, 2023, the projected benefit obligations under the Swiss Plan were approximately $3.3 million, and plan assets were approximately $2.5 million. The funded status of the Swiss Plan is included in other long-term liabilities on the Company's Consolidated Balance Sheets.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property, plant and equipment, net consisted of the following (in thousands ): December 31, 2023 2022 Computers and equipment $ 2,071 $ 2,049 Furniture and fixtures 2,990 2,938 Leasehold improvements 9,692 9,180 Construction-in-progress 169 77 14,922 14,244 Less: Accumulated depreciation (7,443) (5,195) Total property and equipment, net $ 7,479 $ 9,049 The construction-in-process balance consists of costs related to the Company’s leasehold improvements at its facilities in San Diego, California.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
LEASES	LEASES As of December 31, 2023, the Company had two operating leases, including one operating lease with Kilroy Realty, L.P. (the "Landlord") for office space located in San Diego, California, which was entered into in April 2019 and subsequently amended in May 2020. Coinciding with the Company's ability to direct the use of the office space and utilizing a discount rate equal to the Company's estimated incremental borrowing rate, the Company established ROU assets totaling $34.6 million and lease liabilities totaling $34.5 million. The total ROU asset and lease liability at measurement were each offset by lease incentives associated with tenant improvement allowances totaling $7.9 million. The initial term of the office lease ends in August 2028, and the Landlord has granted the Company an option to extend the term of the lease by a period of 5 years. At lease inception, it was not reasonably certain that the Company will extend the term of the lease and therefore the renewal period has been excluded from the aforementioned ROU asset and lease liability measurements. The measurement of the lease term occurs from the February 2021 occupancy date of the office space. The Company also has one operating lease with Esprit Investments Limited for office space located in Dublin, Ireland, which was entered into in October 2022. The initial term of the office lease ends in September 2027. The lease provides the option to extend the term of the lease by a period of 5 years, although at lease inception, it was not reasonably certain that the Company will elect this option and therefore the renewal period has been excluded from the initial lease measurement. Utilizing a discount rate equal to the Company's borrowing rate, the Company established an ROU asset and corresponding lease liability of $0.4 million. The following is a schedule of the future minimum rental commitments for our operating leases reconciled to the lease liability and ROU asset as of December 31, 2023 ( in thousands ): December 31, 2023 2024 $ 6,501 2025 6,673 2026 6,889 2027 7,064 2028 4,781 Thereafter — Total undiscounted future minimum payments 31,908 Present value discount (4,387) Total lease liability 27,521 Unamortized lease incentives (4,591) Cash payments in excess of straight-line lease expense (4,869) Total ROU asset $ 18,061 The weighted-average remaining lease term and weighted-average discount rate of the Company's operating leases are as follows: December 31, 2023 2022 Weighted-average remaining lease term in years 4.7 5.7 Weighted-average discount rate 6.48 % 6.48 % For the year ended December 31, 2023, 2022 and 2021 the Company recorded $4.9 million, $5.0 million, and $4.9 million, respectively, in expense related to operating leases, including amortized tenant improvement allowances.

DIVESTITURES

DIVESTITURES	12 Months Ended
	Dec. 31, 2023
Discontinued Operations and Disposal Groups [Abstract]
DIVESTITURES	DIVESTITURES Discontinued Operations Sale of Bile Acid Product Portfolio On August 31, 2023, the Company closed the sale of its bile acid business to Mirum Pharmaceuticals pursuant to the terms of the Purchase Agreement dated July 16, 2023 between the Company and Mirum. The assets sold consisted of substantially all of the assets primarily related to the Company’s business of development, manufacture (including synthesis, formulation, finishing or packaging) and commercialization of the products, Chenodal and Cholbam (also known as Kolbam). In connection with the Closing, the Company received an upfront cash payment of $210.0 million. Pursuant to the Purchase Agreement, after the Closing, the Company is eligible to receive up to $235.0 million upon the achievement of certain milestones based on specified amounts of annual net sales (tiered from $125.0 million to $500.0 million) of the Products. The Company will recognize the contingent consideration receivable in earnings when the target annual sales for the milestones are met and the contingency is resolved. The Company's sale of the bile acid business resulted in a gain, net of tax, of $226.0 million. The net gain consists of net consideration, including the upfront payment and the deduction of investment banker fees owed upon the Closing, plus the derecognition of the carrying value of the net liabilities included in the transaction and the immaterial tax due on the sale. The Company and Mirum have also entered into a transition services agreement ("TSA") pursuant to which the Company has agreed to perform certain services for a period of time following the Closing, with respect to Mirum’s use and operation of the assets purchased in the Purchase Agreement. The TSA is designed to ensure and facilitate an orderly transfer of business operations, and the consideration to be received by the Company primarily consists of cost reimbursement. For the year ended December 31, 2023, the Company recognized $1.0 million, included in continuing operations within other income (expense), net, of which the Company collected $0.6 million as of December 31, 2023. As part of the TSA, the Company is collecting certain receivables related to purchased assets for a period of time and remitting them to Mirum. The transition services accrual as of December 31, 2023 was $12.3 million, and is included in accrued expenses in the accompanying consolidated balance sheets. TSA services provided by the Company are not anticipated to last beyond 12 months post-close. The Company determined that the divestiture represents a strategic shift that will have a major effect on the Company's operations and financial results, and has therefore reflected the bile acid business as a discontinued operation for all periods presented. Results of discontinued operations are as follows ( in thousands ): Year Ended December 31, 2023 2022 2021 Net product sales $ 66,164 $ 102,558 $ 95,654 Total revenue 66,164 102,558 95,654 Operating expenses: Cost of goods sold 1,899 3,172 2,966 Research and development 6,118 8,447 9,169 Selling, general and administrative 19,500 22,686 23,599 Change in fair value of contingent consideration (473) 15,006 22,260 Total operating expenses 27,044 49,311 57,994 Operating income 39,120 53,247 37,660 Other income (expenses), net: Interest expense (191) (261) (459) Gain on disposal of discontinued operations, net of tax 226,005 — — Total other income (expense), net 225,814 (261) (459) Income from discontinued operations before income tax 264,934 52,986 37,201 Income tax on discontinued operations — — — Net income from discontinued operations $ 264,934 $ 52,986 $ 37,201 Assets and liabilities of discontinued operations presented in the Consolidated Balance Sheets as of December 31, 2022 include the following ( in thousands ): December 31, 2022 Assets Current assets: Inventory $ 2,399 Prepaid expenses and other current assets 591 Total current assets of discontinued operations 2,990 Intangible assets, net 47,965 Other assets 377 Total assets of discontinued operations $ 51,332 Liabilities Current liabilities: Business combination-related contingent consideration, current portion $ 7,000 Total current liabilities of discontinued operations 7,000 Business combination-related contingent consideration, less current portion 64,200 Total liabilities of discontinued operations $ 71,200

QUARTERLY FINANCIAL INFORMATION

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	12 Months Ended
	Dec. 31, 2023
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	QUARTERLY FINANCIAL INFORMATION (UNAUDITED) The following table presents selected consolidated statements of operations data for each quarter for the fiscal years ended December 31, 2023 and 2022 (unaudited, in thousands, except for per share data) : Quarter First Second Third Fourth For the year ended December 31, 2023: Total revenue $ 30,888 $ 32,196 $ 37,095 $ 45,059 Total operating expenses 128,257 136,147 129,680 139,292 Operating loss (97,369) (103,951) (92,585) (94,233) Loss from continuing operations before income tax provision (96,486) (101,867) (89,229) (88,528) Loss from continuing operations, net of tax (96,564) (101,932) (89,241) (88,596) Income (loss) from discontinued operations, net of tax 1 10,233 16,302 239,976 (1,577) Net (loss) income (86,331) (85,630) 150,735 (90,173) (Loss) income per common share - basic and diluted: Continuing operations $ (1.42) $ (1.34) $ (1.17) $ (1.16) Discontinued operations 0.15 0.21 3.14 (0.02) Net (loss) income per common share $ (1.27) $ (1.13) $ 1.97 $ (1.18) For the year ended December 31, 2022: Total revenue $ 23,412 $ 28,634 $ 28,075 $ 29,339 Total operating expenses 95,393 107,160 110,679 116,041 Operating loss (71,981) (78,526) (82,604) (86,702) Loss from continuing operations before income tax provision (81,694) (79,970) (83,918) (85,573) Loss from continuing operations, net of tax (81,746) (80,023) (84,063) (85,636) Income from discontinued operations, net of tax 1 5,775 12,991 14,407 19,813 Net loss (75,971) (67,032) (69,656) (65,823) (Loss) income per common share - basic and diluted: Continuing operations $ (1.29) $ (1.25) $ (1.31) $ (1.33) Discontinued operations 0.09 0.20 0.22 0.30 Net loss per common share $ (1.20) $ (1.05) $ (1.09) $ (1.03) 1 On August 31, 2023, the Company sold its bile acid business, resulting in a gain, net of tax, of $226.0 million. The Company has reflected the bile acid business as a discontinued operation in the Consolidated Financial Statements for all periods presented. See Note 19 for results of discontinued operations and further discussion.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On January 25, 2024, the Company announced that it has entered into an exclusive licensing agreement with Renalys Pharma, Inc. ("Renalys"), to bring sparsentan, a dual endothelin angiotensin receptor antagonist for the treatment of IgAN, to patients in Japan and other countries in Asia. Renalys will hold regional rights to sparsentan for Japan, South Korea, Taiwan, Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam. Under the terms of the agreement, Travere will receive an upfront payment and be eligible to receive up to $120 million in regulatory, development and sales-based milestone payments. As part of the collaboration, Travere has obtained a minority equity stake in Renalys and will be eligible to receive tiered royalties on net sales of sparsentan in the licensed territories. Renalys will be responsible for development, regulatory matters, and commercialization in the licensed territories.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net loss	$ (90,173)	$ 150,735	$ (85,630)	$ (86,331)	$ (65,823)	$ (69,656)	$ (67,032)	$ (75,971)	$ (111,399)	$ (278,482)	$ (180,091)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 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

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation
Use of Estimates	Use of Estimates In preparing financial statements in conformity with U.S. GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of expenses during the reporting period. Due to inherent uncertainty involved in making estimates, actual results reported in future periods may be affected by changes in these estimates. On an ongoing basis, the Company evaluates its estimates and assumptions. These estimates and assumptions include revenue recognition, forecasting probability-weighted cash flows based upon estimates of forecasted revenues, clinical and regulatory timelines and discount rates, valuing equity securities in share-based payments, estimating expenses of contracted research organizations, estimating reserves for inventory, estimating the useful lives of depreciable and amortizable assets, estimating of valuation allowances and uncertain tax positions, and estimates associated with the assessment of impairment for long-lived assets.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Accounting Standards Codification ("ASC") 606, Revenue from Contracts with Customers Deductions from Revenue Revenues from product sales are recorded at the net sales price, which includes provisions resulting from discounts, rebates and co-pay assistance that are offered to customers, payers and other indirect customers relating to the Company’s sales of its products. These provisions are based on the estimates of the amounts earned or to be claimed on the related sales. These amounts are treated as variable consideration, estimated and recognized as a reduction of the transaction price at the time of the sale, using the most likely amount method, and are classified as a reduction of accounts receivable (if the amount is payable to a customer) or as a current liability (if the amount is payable to a party other than a customer). The Company includes these estimated amounts in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized for such transactions will not occur. Where appropriate, these reserves take into consideration the Company’s historical experience, current contractual and statutory requirements and specific known market events and trends. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. If actual results in the future vary from the Company’s provisions, the Company will adjust the estimate, which would affect net product revenue and earnings in the period such variances become known. For the years ended December 31, 2023, 2022 and 2021, the Company recorded a net product revenue increase of $0.4 million, $0.2 million, and $0.2 million, respectively, related to performance obligations satisfied in previous periods. Government Rebates: The Company calculates the rebates that it will be obligated to provide to government programs and deducts these estimated amounts from its gross product sales at the time the revenues are recognized. Allowances for government rebates and discounts are established based on an estimated allocation of payers and the government-mandated discounts applicable to government-funded programs. Rebate discounts are included in accrued expenses in the accompanying consolidated balance sheets. Commercial Rebates: The Company calculates the rebates it incurs according to any contracts with certain commercial payers and deducts these amounts from its gross product sales at the time the revenues are recognized. Allowances for commercial rebates are established based on actual payer information, which is reasonably estimated at the time of delivery for applicable products. Rebate discounts are included in accrued expenses in the accompanying consolidated balance sheets. Prompt Pay Discounts: The Company offers discounts to certain customers for prompt payments. The Company accrues for the calculated prompt pay discount based on the gross amount of each invoice for those customers at the time of sale. Product Returns: Consistent with industry practice, the Company offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product’s expiration date. Historically, returns have been immaterial. Co-pay Assistance: The Company offers a co-pay assistance program, which is intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payers. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the estimated cost per claim associated with product that has been recognized as revenue.
Collaborative Arrangements	Payments received under collaboration and licensing agreements may include non-refundable fees at the inception of the arrangements, milestone payments for specific achievements and royalties on the sale of products. At the inception of arrangements that include milestone payments, the Company uses judgement to evaluate whether the milestones are probable of being achieved and estimates the amount to include in the transaction price utilizing the most likely amount method. If it is probable that a significant revenue reversal will not occur, the estimated amount is included in the transaction price. Milestone payments that are not within the Company or the licensee’s control, such as regulatory approvals, are considered to be constrained due to a high degree of uncertainty and are not included in the transaction price until such uncertainty is resolved. At the end of each reporting period, the Company re-evaluates the probability of achievement of development milestones and any related constraint and adjusts the estimate of the overall transaction price, if necessary. The Company recognizes aggregate sales-based milestones and royalty payments from product sales of which the license is deemed to be the predominant item to which the royalties relate, at the later of when the related sales occur or when the performance obligation to which the sales-based milestone or royalty has been allocated has been satisfied. Revenue from collaboration and licensing agreements may also include sales of inventory, at cost plus a margin, which is recorded in license and collaboration revenue. The Company utilizes significant judgement to develop estimates of the stand-alone selling price for each distinct performance obligation based upon the relative stand-alone selling price. Variable consideration that relates specifically to the Company’s efforts to satisfy specific performance obligations is allocated entirely to those performance obligations. The stand-alone selling price for license-related performance obligations requires judgement in developing assumptions to project probability-weighted cash flows based upon estimates of forecasted revenues, clinical and regulatory timelines and discount rates. The stand-alone selling price for clinical development performance obligations is based on forecasted expected costs of satisfying a performance obligation plus an appropriate margin. If the licenses to intellectual property are determined to be distinct from the other performance obligations identified in the arrangement and have stand-alone functionality, the Company recognizes revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to benefit from the license. For licenses that are not distinct from other promises, the Company applies judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, upfront fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the related revenue recognition accordingly. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. Revenue is recorded proportionally as costs are incurred. The Company generally utilizes the cost-to-cost method of progress because it best measures the transfer of control to the customer which occurs as the Company incurs costs. Under the cost-to-cost measure of progress, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. The Company uses judgment to estimate the total costs expected to complete the clinical development performance obligations, which include subcontractor costs, labor, materials, other direct costs and an allocation of indirect costs. The Company evaluates these cost estimates and the progress each reporting period and adjusts the measure of progress, if necessary.
Inventory, Related Reserves and Capitalization of Inventory Costs	Inventory, which is recorded at the lower of cost or net realizable value, includes materials and other direct and indirect costs and is valued using the first-in, first-out method. The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value, and writes down such inventory as appropriate. In addition, the Company's products are subject to strict quality control and monitoring which the Company’s manufacturers perform throughout their manufacturing process. The Company does not directly manufacture any product. The Company has a single supplier for its product Thiola, and utilizes contract service providers for the manufacture of the active pharmaceutical ingredient for FILSPARI and the manufacture of primary packaging, secondary packaging and serialization for its product FILSPARI. Capitalization of Inventory Costs Prior to the regulatory approval of the Company's therapeutic candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those therapies. The Company capitalizes inventory costs associated with its products after regulatory approval, when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Until the date at which regulatory approval has been received, costs related to the production of inventory are recorded as research and development expenses as incurred. Any eventual sale of previously expensed ("zero-cost") inventories may impact future margins, for any periods in which those inventories are sold. Prior to the February 2023 FDA accelerated approval of FILSPARI (sparsentan), the Company recognized approximately $7.5 million in research and development expenses related to the production of active pharmaceutical ingredients to support the commercial launch of FILSPARI. For the year ended December 31, 2023, sales of FILSPARI primarily consisted of zero-cost inventories. As of December 31, 2023, the Company had $7.2 million of zero-cost inventory remaining. The Company expects to continue to benefit from the sale of previously expensed inventories through at least 2025. The Company began capitalizing inventory costs associated with FILSPARI (sparsentan) following the February 2023 approval for treatment in IgAN. At December 31, 2023, the Company's evaluation of excess inventory and obsolescence considered certain minimum purchase obligations, which in combination with lower forecasted sales of FILSPARI resulted in a $3.2 million charge to cost of goods sold. The charge to cost of goods of sold included a $2.1 million write-down of inventory balances and $1.1 million accrued for firm purchase commitments.
Cost of Goods Sold	Cost of goods sold includes the cost of inventory sold, third party manufacturing and supply chain costs, product shipping, tracking and handling costs, and provisions for excess and obsolete inventory. Cost of goods sold also includes the cost of goods sold under the Company's license and collaboration agreements, which currently consists of the sale of active pharmaceutical ingredients to the Company's collaboration partner, at cost plus a margin.
Research and Development Expenses	Research and Development Expenses Research and development includes expenses related to sparsentan, pegtibatinase, and the Company's other pipeline programs. The Company expenses all research and development costs as they are incurred. The Company's research and development costs are composed of salaries and bonuses, benefits, share-based compensation, license fees, milestones under license agreements, costs paid to third-party contractors to perform research, conduct clinical trials, costs to develop drug materials and delivery devices, costs to manufacture drug product supplies to support clinical development, and associated overhead expenses and facilities costs. The Company charges direct internal and external program costs to the respective development programs. The Company also incurs indirect costs that are not allocated to specific programs because such costs benefit multiple development programs and allow us to increase our pharmaceutical development capabilities. These consist of internal shared resources related to the development and maintenance of systems and processes applicable to all of our programs. Nonrefundable advance payments for goods and services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. During the three months ended December 31, 2022, the Company recorded an out of period adjustment that decreased research and development expenses and related accrued expenses by $7.7 million, $1.5 million of which was previously recorded in fiscal year 2022 and $6.2 million that was originally recorded in fiscal year 2021. The adjustment was the result of a certain pre-launch inventory contract that was not properly evaluated for accounting implications at inception. The Company evaluated the impact of the adjustment and concluded it is not material, individually and in the aggregate, to 2022 or any prior period financial statements.
Clinical Trial Expenses	Clinical Trial Expenses The Company records expenses in connection with its clinical trials under contracts with contract research organizations ("CROs") that support conducting and managing clinical trials, as well as contract manufacturing organizations ("CMOs") for the manufacture of drug product supplies to support clinical development. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up, initiation activities, enrollment, treatment of patients, or the completion of other clinical trial activities, and in the case of CMOs, costs associated with the production of drug product supplied and the procurement of raw materials to be consumed in the manufacturing process. Expenses related to clinical trials are accrued based on our estimates of the progress of services performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials or the delivery of goods. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), the Company adjusts its estimates accordingly on a prospective basis. Revisions to the Company's contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain. The Company currently has one Phase 1/2 clinical trial and three Phase 3 clinical trials in process that are in varying stages of activity, with ongoing non-clinical support trials. As such, clinical trial expenses will vary depending on all the factors set forth above and may fluctuate significantly from quarter to quarter.
Share-Based Compensation	Share-Based Compensation The Company recognizes all employee share-based compensation as a cost within research and development expenses and selling, general, and administrative expenses. Equity-classified awards principally related to stock options, restricted stock units (“RSUs”) and performance stock units ("PSUs"), are measured at the grant date fair value of the award. The Company determines grant date fair value of stock option awards using the Black-Scholes option-pricing model. The fair value of RSUs and PSUs are determined using the closing price of the Company’s common stock on the grant date. For service based vesting grants, expense is recognized over the requisite service period. For PSUs, expense is recognized over the implicit service period, assuming vesting is probable. No expense is recognized for PSUs if it is not probable the vesting criteria will be satisfied. Forfeitures are accounted for as they occur. Expiration Term Vesting Term Stock Options 10 years 3 to 4 years Restricted Stock Units ---- 1 to 4 years
Earnings (Loss) Per Share	Earnings (Loss) Per Share The Company calculates basic earnings per share by dividing net income/(loss) by the weighted average number of shares outstanding during the period. Pre-funded warrants issued and sold by the Company to purchase shares of its common stock are included in the calculation of basic net loss per common share if the exercise price of the pre-funded warrant represents little consideration and is non-substantive in relation to the price paid for the warrant, and if the warrants are immediately exercisable with no further vesting conditions or contingencies associated with them. The Company's diluted earnings/(loss) per share computation includes the effect, if any, of shares that would be issuable upon the exercise of outstanding stock options, convertible debt and RSUs, reduced by the number of shares which are assumed to be purchased by the Company from the resulting proceeds at the average market price during the year, when such amounts are dilutive to the earnings per share calculation. In accordance with ASC 260, Earnings per Share , if a company had a discontinued operation, the company uses income from continuing operations, adjusted for preferred dividend and similar adjustments, as its control number to determine whether potential common shares are dilutive.
Cash and Cash Equivalents	Cash and Cash Equivalents
Concentration of Credit Risk	Concentration of Credit Risk The Company maintains its cash and cash equivalents at insured financial institutions, the balances of which may, at times, exceed federally insured limits. Generally, these deposits may be redeemed upon demand, and the Company believes there is minimal risk of losses on such balances. The Company monitors its investments with counterparties with the objective of minimizing concentrations of credit risk. The Company's investment policy is to invest only in institutions that meet high credit quality standards and established limits on the amount and time to maturity of investments with any individual counterparty. The policy also requires that investments are only entered into with corporate and financial institutions that meet high quality standards.
Marketable Debt Securities	Marketable Debt Securities The Company classified marketable debt securities held as “available-for-sale” and carries them at fair value. The Company classifies these investments as current assets, even if the maturity when acquired by the Company is greater than one year due to the ability to liquidate within the next 12 months. The amortized cost of marketable debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, is included in interest income. Unrealized gains and losses on marketable debt securities are recorded as a separate component of stockholders’ equity as accumulated other comprehensive loss, unless an impairment is determined to be the result of credit-related factors or the Company intends to sell the security or it is more likely than not that the Company will be required to sell the security before recovery. Unrealized losses that are determined to be credit-related are recorded as an allowance against the amortized cost basis. Realized gains or losses on debt security transactions and declines in value that are determined to be the result of credit losses, if any, are reported in other income or expense in the Consolidated Statements of Operations and Comprehensive Loss. The cost of securities sold is based on the specific identification method. Marketable debt securities are maintained at one financial institution and are governed by the Company’s investment policy. See Note 6 for further discussion.
Accounts Receivables, Net	Accounts Receivables, Net
Supplier Concentration Risk	Supplier Concentration Risk The Company has no manufacturing capabilities and relies on third party manufacturers who are sole source suppliers for manufacturing of its products. The Company intends to rely on third-party manufacturers for the long-term commercial supply of FILSPARI and for its development stage product candidates, including sparsentan for the treatment of FSGS and pegtibatinase. The Company expects the manufacturers of each product or product candidate to, at least initially and potentially for a significant period of time, be single source suppliers to the Company.
Segment Information	Segment Information The Company currently operates in one operating segment focused on the development and commercialization of innovative therapies for people with serious and life-threatening rare diseases and medical conditions. The Company is not organized by market and is managed and operated as one business. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate products, other than revenues, and does not have separately reportable segments.
Property and Equipment, net	Property and Equipment, net Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed using the straight-line method over the related estimated useful lives as presented in the table below. Significant additions and improvements are capitalized, while repairs and maintenance are charged to expense as incurred. Property and equipment purchased for specific research and development projects with no alternative use is expensed as incurred. The major classifications of property and equipment, including their respective expected useful lives, consist of the following: Computers and equipment 3 years Furniture and fixtures 7 years Leasehold improvements Shorter of length of lease or life of the asset
Leases	Leases The Company determines whether a contract is, or contains, a lease at inception. The Company classifies each of its leases as operating or financing considering factors such as the length of the lease term, the present value of the lease payments, the nature of the asset being leased, and the potential for ownership of the asset to transfer during the lease term. Leases with terms greater than one year are recognized on the Consolidated Balance Sheets as Right-of-use assets and Lease liabilities and are measured at the present value of the fixed payments due over the expected lease term minus the present value of any incentives, rebates or abatement expected to be received from the lessor. Options to extend a lease are typically excluded from the expected lease term as the exercise of the option is typically not reasonably certain. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the appropriate incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis an amount equal to the lease payments over a similar term and in a similar economic environment. In addition to rent, the leases may require the Company to pay additional amounts for taxes, insurance, maintenance, and other expenses, which are generally referred to as non-lease components. The Company has elected to not separate lease and non-lease components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease component and recognized as part of the Right-of-use assets and Lease liabilities. The Company records expense to recognize fixed lease payments, including payment escalation, on a straight-line basis over the expected lease term. Costs determined to be variable and not based on an index or rate are not included in the measurement of the lease liability and are expensed as incurred.
Intangible Assets, Net and Intangible Assets with Cost Accumulation Model	Intangible Assets, Net The Company's intangible assets consist of licenses and purchased technology. Intangible assets with definite lives are amortized on a straight-line basis over their estimated useful lives and are reviewed periodically for impairment. Intangible Assets with Cost Accumulation Model In 2014, the Company entered into a license agreement with Mission Pharmacal in which the Company obtained the exclusive right to license the trademark of Thiola. The acquisition of the Thiola license qualified as an asset acquisition under the principles of ASC 805, Business Combinations ("ASC 805") in effect at the time of acquisition. The license agreement requires the Company to make royalty payments based on net sales of Thiola. The liability for royalties in excess of the annual contractual minimum is recognized in the period in which the royalties become probable and estimable, which is typically in the period corresponding with the respective sales. The Company records an offsetting increase to the cost basis of the asset under the cost accumulation model ("Thiola Intangible"). The additional cost basis is subsequently amortized over the remaining useful life. In the second quarter of 2023, the Company reduced the estimated useful life of the Thiola Intangible to better reflect the pattern of projected future cash flows, resulting in incremental expense of $3.7 million recorded in selling, general, and administrative Consistent with all prior periods since Thiola was acquired, the Company has not accrued any liability for future royalties in excess of the annual contractual minimum at December 31, 2023 as such royalties are not yet probable and estimable.
Variable Interest Entity	Variable Interest Entity The Company reviews each investment and collaboration agreement to determine if it has a variable interest in the entity. In assessing whether the Company has a variable interest in the entity as a whole, the Company considers and makes judgements regarding the purpose and design of the entity, the value of the licensed assets to the entity, the value of the entity’s total assets and the significant activities of the entity. If the Company has a variable interest in the entity as a whole, the Company assesses whether or not the Company is a primary beneficiary of that VIE, based on a number of factors, including: (i) which party has the power to direct the activities that most significantly affect the VIE’s economic performance, (ii) the parties’ contractual rights and responsibilities pursuant to the collaboration agreement, and (iii) which party has the obligation to absorb losses of or the right to receive benefits from the VIE that could be significant to the VIE. If the Company determines that it is the primary beneficiary of a VIE at the onset of the collaboration, the collaboration is treated as a business combination and the Company consolidates the financial statements of the VIE into the Company’s consolidated financial statements. On a quarterly basis, the Company evaluates whether it continues to be the primary beneficiary of the consolidated VIE. If the Company determines that it is no longer the primary beneficiary of a consolidated VIE, it deconsolidates the VIE in the period in which the determination is made. Assets and liabilities recorded as a result of consolidating the financial results of the VIE into the Company’s consolidated balance sheet do not represent additional assets that could be used to satisfy claims against the Company’s general assets or liabilities for which creditors have recourse to the Company’s general assets.
Goodwill	Goodwill
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company's long-lived assets are primarily comprised of intangible assets, right-of-use assets, and property and equipment. The Company evaluates its finite-lived intangible assets, right-of-use assets, and property and equipment for impairment whenever events or changes in circumstances indicate the carrying value of an asset or group of assets may not be recoverable. If these circumstances exist, recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future undiscounted net cash flows expected to be generated by the use and eventual disposition of the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. In addition, indefinite-lived intangible assets are reviewed for impairment annually and whenever events or changes in circumstances indicate that it is more likely than not that the asset is impaired by comparing the fair value to the carrying value of the asset. To determine the fair value of the asset, the Company used the multi-period excess earnings method of the income approach. The more significant assumptions inherent in the application of this method include: the amount and timing of projected future cash flows (including revenue, cost of sales, research and development costs, and sales and marketing expenses), and the discount rate selected to measure the risks inherent in the future cash flows.
Income Taxes	Income Taxes The Company follows ASC 740, Income Taxes ("ASC 740"), which requires recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance to the extent management concludes it is more likely than not that the asset will not be realized. The standard addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the tax authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. ASC 740 also provides guidance on de-recognition, classification, interest and penalties on income taxes, accounting in interim periods and requires increased disclosures. The Company’s policy is to record estimated interest and penalty related to the underpayment of income taxes or unrecognized tax benefits as a component of its income tax provision.
Foreign Currency Translation	Foreign Currency Translation Functional and presentation currency Items included in the financial statements of each entity comprising the Company are measured using the currency of the primary economic environment in which the entity operates (the functional currency). Transactions and balances Foreign currency transactions in each entity comprising the Company are remeasured into the functional currency of the entity using the exchange rates prevailing at the respective transaction dates. Foreign exchange gains and losses resulting from the settlement of such transactions and from the remeasurement at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized within Other income (expense), net in the Consolidated Statements of Operations and Comprehensive Loss. The aggregate gain arising from foreign exchange transactions included in other income (expense), net for the years ended December 31, 2023, 2022 and 2021 was $0.5 million, $1.4 million, and $0.3 million, respectively. The results and financial position of the Company that have a functional currency different from the US dollar are translated as follows: a. assets and liabilities presented are translated at the closing exchange rate as of December 31, 2023 and 2022; b. income and expenses for the statements of operations and comprehensive loss are translated at average exchange rates that are relevant for the respective periods for which the income and expenses occurred; and c. significant transactions use the exchange rate on the date of the transaction. All resulting exchange differences arising from such translations are recognized directly in comprehensive income and presented as a separate component of equity.
Reclassifications	Reclassifications Certain reclassifications have been made to the prior year financial statements in order to conform to the current year’s presentation, including reclassifying the prior period carrying values of the assets and liabilities included in the sale of the bile acid business as assets and liabilities of discontinued operations within the Consolidated Balance Sheets, and revenues and expenses attributable to the bile acid business as net income from discontinued operations. These reclassifications did not have an impact on total assets or total liabilities in the Consolidated Balance Sheets or net loss in the Consolidated Statements of Operations.
Patents	Patents The Company expenses external costs, such as filing fees and associated attorney fees, incurred to obtain issued patents and patent applications pending. The Company also expenses costs associated with maintaining and defending patents subsequent to their issuance in the period incurred.
Legal Contingencies	Legal Contingencies
Discontinued Operations	Discontinued Operations
Restructuring	Restructuring Restructuring charges consist primarily of employee severance, one-time termination benefits related to the reduction of its workforce, and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the entity notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the service period. Termination benefits are calculated based on a regional benefit practices and local statutory requirements. In December 2023, the Company initiated a restructuring plan that resulted in a reduction of its workforce, primarily impacting non-field-based employees. One-time termination benefits include severance, continuation of health insurance coverage, and other benefits for a specified period of time. The Company estimates that it will incur a total of $12.0 million to $14.0 million in non-recurring charges in connection with the restructuring, of which the Company has recognized $11.4 million for the year ended December 31, 2023. As of December 31, 2023, the Company recorded accrued restructuring costs of $11.4 million, which is included in accrued expenses of the Consolidated Balance Sheets. No cash payments were made related to the restructuring during 2023. The Company expects that it will incur the remaining estimated restructuring costs during 2024. The Company intends to pay all restructuring plan amounts during 2024.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2020, the FASB issued ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity. The ASU includes amendments to the guidance on convertible instruments and the derivative scope exception for contracts in an entity's own equity in Subtopic 815-40 and simplifies the accounting for convertible instruments which include beneficial conversion features or cash conversion features by removing certain separation models in Subtopic 470-20. Additionally, the ASU requires entities to use the "if-converted" method when calculating diluted earnings per share for convertible instruments. The adoption of the new standard impacted the Company's accounting for its Convertible Senior Notes Due 2025 (2025 Notes), discussed in Note 7, which were previously accounted for using the cash conversion model applied under ASC 470-20, Debt with Conversion and Other Options ("ASC 470-20"). The Company adopted ASU 2020-06 on January 1, 2022 using the modified retrospective method. The cumulative effect of the accounting change as of January 1, 2022 increased the carrying amount of the 2025 Notes by $44.7 million, reduced additional paid-in capital by $74.9 million, and reduced accumulated deficit by $30.2 million. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board ("FASB") or other standard setting bodies. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures. This new standard does not change accounting for income taxes but requires new disclosures focusing on two areas, the effective rate reconciliation and taxes paid. This new standard is effective for public business entities for annual periods beginning after December 15, 2024. Early adoption is permitted. The Company expects to adopt this new standard beginning in fiscal 2025 when it becomes effective. In November 2023, the FASB issued ASU No. 2023-07, Improvements to Reportable Segment Disclosure. The FASB amended the guidance in ASC 280, Segment Reporting ("ASC 280"), to require a public entity to disclose significant segment expenses and other segment items on an annual and interim basis and to provide in interim periods all disclosures about a reportable segment's profit or loss and assets that are currently required annually. Public entities with a single reportable segment are required to provide the new disclosures and all the disclosures required under ASC 280. The guidance is applied retrospectively to all periods presented in financial statements, unless it is impracticable. This new guidance is effective for public business entities for annual periods beginning after December 15, 2023. Early adoption is permitted. The Company will adopt this new guidance beginning in fiscal 2024 when it becomes effective.
Fair Value Measurements	The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are described below: Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The valuation techniques used to measure the fair value of the Company’s debt securities and all other financial instruments, all of which have counterparties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. Based on the fair value hierarchy, the Company classified marketable debt securities within Level 2.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Inventory, Net of Reserves	Inventory, net of reserves, consisted of the following at December 31, 2023 and 2022 ( in thousands ): December 31, 2023 December 31, 2022 Raw materials $ 33,790 $ 2,397 Work in process 4,727 — Finished goods 2,387 2,126 Total inventory $ 40,904 $ 4,523 Classified as: Inventory, net $ 9,410 $ 4,523 Long-term inventory, net 31,494 — Total inventory $ 40,904 $ 4,523
Schedule Of Cost Of Goods Sold	The following table summarizes cost of goods sold for the years ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Cost of goods sold - product sales $ 8,406 $ 4,420 $ 3,818 Cost of goods sold - license and collaboration 3,044 — — Total cost of goods sold $ 11,450 $ 4,420 $ 3,818
Schedule of Vesting Award Terms	Expiration Term Vesting Term Stock Options 10 years 3 to 4 years Restricted Stock Units ---- 1 to 4 years
Schedule of Major Classifications of Property and Equipment	The major classifications of property and equipment, including their respective expected useful lives, consist of the following: Computers and equipment 3 years Furniture and fixtures 7 years Leasehold improvements Shorter of length of lease or life of the asset Property, plant and equipment, net consisted of the following (in thousands ): December 31, 2023 2022 Computers and equipment $ 2,071 $ 2,049 Furniture and fixtures 2,990 2,938 Leasehold improvements 9,692 9,180 Construction-in-progress 169 77 14,922 14,244 Less: Accumulated depreciation (7,443) (5,195) Total property and equipment, net $ 7,479 $ 9,049
Schedule of Foreign Currency Translation Adjustment Included in Accumulated Other Comprehensive Loss	The following table summarizes the foreign currency translation adjustment included in accumulated other comprehensive loss for the year ended December 31, 2023, 2022 and 2021 ( in thousands ): Foreign Currency Translation Adjustments included in Accumulated Other Comprehensive Loss 2023 2022 2021 Balance at January 1, $ 415 $ (92) $ (1,607) Foreign currency translation adjustments (1,871) 507 1,515 Balance at December 31, $ (1,456) $ 415 $ (92)
Schedule of Restructuring and Related Costs	2023 Liability balance at January 1, $ — Restructuring expenses 11,394 Foreign currency impact 27 Liability balance at December 31, $ 11,421

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Net Product Sales	The following table summarizes net product sales for the year ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Tiopronin products $ 98,329 $ 97,970 $ 115,122 FILSPARI 29,208 — — Total net product sales $ 127,537 $ 97,970 $ 115,122

COLLABORATION AND LICENSE AGR_2

COLLABORATION AND LICENSE AGREEMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Changes in Deferred Revenue	The following table sets forth a summary of changes in deferred revenue for the years ended December 31, 2023, 2022 and 2021 (in thousands) : Deferred Revenue 2023 2022 2021 Balance at January 1, $ 22,907 $ 36,647 $ — New consideration resulting in deferred revenue — — 55,000 License and collaboration revenue (14,363) (11,490) (16,714) Foreign currency impact 387 (2,250) (1,639) Balance at December 31, $ 8,931 $ 22,907 $ 36,647

MARKETABLE DEBT SECURITIES (Tab

MARKETABLE DEBT SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Debt Securities	Marketable debt securities consisted of the following ( in thousands ): As of December 31, 2023 2022 Marketable debt securities: Commercial paper $ 34,458 $ 123,647 Corporate debt securities 368,323 224,055 Securities of government-sponsored entities 105,894 40,855 Total available-for-sale marketable debt securities $ 508,675 $ 388,557
Schedule of Short-term Marketable Debt Securities	The following is a summary of short-term marketable debt securities classified as available-for-sale as of December 31, 2023 ( in thousands ): Remaining Contractual Maturity Amortized Cost Unrealized Gains Unrealized Losses Aggregate Estimated Fair Value Marketable debt securities: Commercial paper Less than 1 $ 34,450 $ 25 $ (17) $ 34,458 Corporate debt securities Less than 1 133,463 29 (408) 133,084 Securities of government-sponsored entities Less than 1 81,334 36 (274) 81,096 Total maturity less than 1 year 249,247 90 (699) 248,638 Corporate debt securities 1 to 2 233,969 1,444 (174) 235,239 Securities of government-sponsored entities 1 to 2 24,718 106 (26) 24,798 Total maturity 1 to 2 years 258,687 1,550 (200) 260,037 Total available-for-sale marketable debt securities $ 507,934 $ 1,640 $ (899) $ 508,675 The following is a summary of short-term marketable debt securities classified as available-for-sale as of December 31, 2022 ( in thousands ): Remaining Contractual Maturity Amortized Cost Unrealized Gains Unrealized Losses Aggregate Estimated Fair Value Marketable debt securities: Commercial paper Less than 1 $ 124,301 $ 2 $ (656) $ 123,647 Corporate debt securities Less than 1 155,841 — (1,355) 154,486 Securities of government-sponsored entities Less than 1 7,473 — (80) 7,393 Total maturity less than 1 year 287,615 2 (2,091) 285,526 Corporate debt securities 1 to 2 70,195 33 (659) 69,569 Securities of government-sponsored entities 1 to 2 33,702 6 (246) 33,462 Total maturity 1 to 2 years 103,897 39 (905) 103,031 Total available-for-sale marketable debt securities $ 391,512 $ 41 $ (2,996) $ 388,557
Schedule of Debt Securities in Unrealized Loss Position	The following is a summary of available-for-sale marketable debt securities in an unrealized loss position with no credit losses reported as of December 31, 2023 ( in thousands ): Less Than 12 Months 12 Months or Greater Total Description of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 24,798 $ 17 $ — $ — $ 24,798 $ 17 Corporate debt securities 140,802 405 28,775 177 169,577 582 Securities of government-sponsored entities 61,933 217 12,540 83 74,473 300 Total $ 227,533 $ 639 $ 41,315 $ 260 $ 268,848 $ 899 The following is a summary of available-for-sale marketable debt securities in an unrealized loss position with no credit losses reported as of December 31, 2022 ( in thousands ): Less Than 12 Months 12 Months or Greater Total Description of Securities Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Commercial paper $ 117,853 $ 656 $ — $ — $ 117,853 $ 656 Corporate debt securities 99,066 1,041 107,964 973 207,030 2,014 Securities of government-sponsored entities 31,402 263 4,456 63 35,858 326 Total $ 248,321 $ 1,960 $ 112,420 $ 1,036 $ 360,741 $ 2,996

CONVERTIBLE NOTES PAYABLE (Tabl

CONVERTIBLE NOTES PAYABLE (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The composition of the Company’s convertible senior notes are as follows ( in thousands ): December 31, 2023 December 31, 2022 2.25% convertible senior notes due 2029 $ 316,250 $ 316,250 2.50% convertible senior notes due 2025 68,904 68,904 Unamortized debt issuance costs - 2.25% convertible senior notes due 2029 (7,348) (8,750) Unamortized debt issuance costs - 2.50% convertible senior notes due 2025 (543) (859) Total convertible senior notes, net of unamortized debt discount and debt issuance costs $ 377,263 $ 375,545 The following table sets forth total interest expense recognized related to the 2025 and 2029 Notes ( in thousands ): Year Ended December 31, 2023 2022 2021 Contractual interest expense $ 8,838 $ 8,433 $ 6,900 Amortization of debt discount — — 10,339 Amortization of debt issuance costs 1,718 1,622 903 Total interest expense for the 2025 and 2029 Notes $ 10,556 $ 10,055 $ 18,142

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value on a Recurring Basis	The following table presents the Company’s assets, measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2023 (in thousands): As of December 31, 2023 Fair Value Hierarchy at December 31, 2023 Total carrying and estimated fair value Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets: Cash and Cash Equivalents $ 58,176 $ 58,176 $ — $ — Marketable debt securities, available-for-sale 508,675 — 508,675 — Total $ 566,851 $ 58,176 $ 508,675 $ — The following table presents the Company’s assets, measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of December 31, 2022 (in thousands): As of December 31, 2022 Fair Value Hierarchy at December 31, 2022 Total carrying and estimated fair value Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets: Cash and Cash Equivalents $ 61,688 $ 61,688 $ — $ — Marketable debt securities, available-for-sale 388,557 — 388,557 — Total $ 450,245 $ 61,688 $ 388,557 $ —

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Amortizable Intangible Assets	Amortizable intangible assets as of December 31, 2023 ( in thousands ): Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Thiola license 12 $ 155,589 $ (77,311) $ 78,278 Ligand license 11 27,448 (2,036) 25,412 Total amortizable intangible assets $ 183,037 $ (79,347) $ 103,690 Amortizable intangible assets as of December 31, 2022 ( in thousands ): Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Thiola license 12 $ 139,383 $ (50,324) $ 89,059 Ligand license 11 19,400 (12,139) 7,261 Total amortizable intangible assets $ 158,783 $ (62,463) $ 96,320
Schedule of Amortization Expense	The following table summarizes amortization expense for the year ended December 31, 2023, 2022 and 2021 ( in thousands ): 2023 2022 2021 Selling, general and administrative $ 29,021 $ 12,339 $ 9,888 Research and development 7,261 6,264 1,158 Total amortization expense $ 36,282 $ 18,603 $ 11,046 As of December 31, 2023, amortization expense for the next five years and thereafter is expected to be as follows ( in thousands ): 2024 $ 37,625 2025 40,709 2026 8,347 2027 2,722 2028 2,729 Thereafter 11,558 Total $ 103,690

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following at December 31, 2023 and 2022 ( in thousands ): 2023 2022 Compensation related costs $ 29,908 $ 35,267 Research and development 26,006 26,070 Sales discounts, rebates, and allowances 13,730 13,486 Transition services accrual 12,282 — Accrued restructuring costs 11,421 — Selling, general and administrative 7,190 8,791 Accrued royalties 6,991 7,755 Miscellaneous accrued 11,463 4,373 Total accrued expenses $ 118,991 $ 95,742

STOCKHOLDERS_ EQUITY (Tables)

STOCKHOLDERS’ EQUITY (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Assumptions used in Black-scholes Options Pricing Model	The following weighted average assumptions were used in the Black-Scholes options pricing model to estimate the fair value of stock options for the specified reporting periods: Year Ended December 31, 2023 2022 2021 Risk free rate 3.9 % 1.7 % 0.6 % Expected volatility 50 % 50 % 59 % Expected life (in years) 6.4 6.4 6.4 Expected dividend yield — — —
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes our stock option activity and related information for the year ended December 31, 2023: Weighted Average Shares Underlying Exercise Remaining Aggregate Outstanding at December 31, 2022 9,932,422 $ 21.56 5.79 $ 24,658 Granted 1,157,750 21.69 — — Forfeited and expired (652,156) 24.98 — — Exercised (226,663) 14.30 — 1,422 Outstanding at December 31, 2023 10,211,353 $ 21.52 4.91 $ — Vested and expected to vest at December 31, 2023 10,211,353 $ 21.52 4.88 $ — The following table summarizes our stock options exercisable at December 31, 2023, 2022 and 2021: Weighted Average Shares Underlying Exercise Remaining Aggregate Exercisable at December 31, 2021 6,011,349 $ 19.34 5.16 $ 71,063 Exercisable at December 31, 2022 6,999,669 $ 20.22 4.62 $ 21,806 Exercisable at December 31, 2023 7,942,964 $ 20.85 3.95 $ —
Schedule of Restricted Stock Unit Activity	The following table summarizes our restricted stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 2,343,709 $ 24.65 Granted 1,907,542 21.20 Vested (803,113) 23.30 Forfeited/cancelled (574,092) 23.48 Unvested December 31, 2023 2,874,046 $ 22.97
Schedule of Performance-based Stock Unit Activity	The following table summarizes our performance-based stock unit activity for the year ended December 31, 2023: Number of Weighted Average Unvested December 31, 2022 157,048 $ 25.24 Granted 66,250 22.40 Vested (16,500) 15.46 Forfeited/cancelled (31,340) 22.31 Unvested December 31, 2023 175,458 $ 25.61
Schedule of Non-cash Stock-based Compensation Expense	Total non-cash stock-based compensation expense consisted of the following for the years ended December 31, 2023, 2022 and 2021 ( in thousands ): Year Ended December 31, 2023 2022 2021 Selling, general and administrative expenses $ 27,111 $ 24,368 $ 17,009 Research and development expenses 17,135 13,775 12,557 Total stock-based compensation expense $ 44,246 $ 38,143 $ 29,566

NET LOSS PER COMMON SHARE (Tabl

NET LOSS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share is calculated as follows (net loss amounts are stated in thousands) : For the year ended December 31, 2023 2022 2021 Shares Net (loss) income EPS Shares Net (loss) income EPS Shares Net (loss) income EPS Continuing operations 74,267,418 $ (376,333) $ (5.07) 63,758,515 $ (331,468) $ (5.20) 59,832,287 $ (217,292) $ (3.63) Discontinued operations 74,267,418 $ 264,934 $ 3.57 63,758,515 $ 52,986 $ 0.83 59,832,287 $ 37,201 $ 0.62 Basic and diluted loss per share 74,267,418 $ (111,399) $ (1.50) 63,758,515 $ (278,482) $ (4.37) 59,832,287 $ (180,091) $ (3.01)
Schedule of Anti-dilutive Securities	For the years ended December 31, 2023, 2022 and 2021, the following weighted-average number of common stock equivalents were excluded because they were anti-dilutive: For the year ended December 31, 2023 2022 2021 Convertible debt 11,697,952 10,869,000 7,113,402 Options 10,555,550 10,041,249 9,214,188 Restricted stock units and performance-based stock units 3,417,245 2,175,100 1,569,470 Total anti-dilutive shares 25,670,747 23,085,349 17,897,060

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Net Loss from Continuing Operations Before Income Taxes	For financial reporting purposes, net loss from continuing operations before income taxes includes the following components ( in thousands ): Year Ended December 31, 2023 2022 2021 United States $ (293,283) $ (268,887) $ (161,333) Foreign (82,827) (62,268) (55,550) Total $ (376,110) $ (331,155) $ (216,883)
Schedule of Components of Provision (Benefit) for Income Taxes	The components of the provision for income taxes, in the Consolidated Statements of Operations are as follows ( in thousands ): 2023 2022 2021 Current Federal $ — $ — $ — State 223 314 412 Foreign — (1) (3) 223 313 409 Deferred Federal — — — State — — — — — — Total tax provision $ 223 $ 313 $ 409
Schedule of Reconciliation of Statutory Federal Income Tax Rate	The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate expressed as a percentage of loss before income taxes: 2023 2022 2021 Statutory rate - federal (21.00) % (21.00) % (21.00) % State taxes, net of federal benefit (3.19) % (3.62) % (2.92) % Foreign rate differential 1.29 % 0.81 % 2.72 % Nondeductible executive compensation 1.50 % 0.41 % 0.40 % Excess tax benefits associated with share-based awards 0.68 % (0.17) % 0.15 % Other permanent differences 0.37 % 0.17 % 0.12 % Tax credits (1.13) % (5.29) % (8.65) % Return to provision adjustments and other true-ups 4.19 % (0.17) % 2.00 % Adoption of ASU 2020-06 — % (3.54) % — % Other 0.57 % — % 0.18 % Change in valuation allowance 16.78 % 32.49 % 27.19 % Income tax provision (benefit) 0.06 % 0.09 % 0.19 %
Schedule of Deferred Tax Assets and Liabilities	The significant components of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022 are as follows ( in thousands ): 2023 2022 Deferred Tax Assets: Net operating loss $ 81,531 $ 49,811 Research and development and other tax credits 77,555 91,052 Capitalized research and development 39,907 36,442 Contingent consideration — 18,124 Other accrued expenses 13,187 13,247 Stock based compensation 21,607 22,936 Charitable contributions 6,110 4,781 Intangible assets greater than book 47,731 51,391 Interest expense limitation 1,679 4,346 Operating lease liabilities 6,812 8,018 Tax basis depreciation greater than book depreciation 292 105 Difference in basis of loan costs 62 15 296,473 300,268 Deferred Tax Liabilities: Operating lease right of use assets (5,595) (6,658) Prepaid assets (198) (206) (5,793) (6,864) Net deferred tax assets before valuation allowance 290,680 293,404 Valuation allowance (290,680) (293,404) Total deferred tax assets $ — $ —
Schedule of Unrecognized Tax Benefits	A reconciliation of the Company's unrecognized tax benefits for the years 2023 and 2022 is provided in the following table ( in thousands ): 2023 2022 Balance as of January 1: $ 11,490 $ 7,825 Increase in current period positions 4,871 2,056 Increase in prior period positions 7,383 1,919 Decrease in prior period positions (838) — Decrease due to settlements with tax authorities — (310) Balance as of December 31: $ 22,906 $ 11,490

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant, and Equipment, Net	The major classifications of property and equipment, including their respective expected useful lives, consist of the following: Computers and equipment 3 years Furniture and fixtures 7 years Leasehold improvements Shorter of length of lease or life of the asset Property, plant and equipment, net consisted of the following (in thousands ): December 31, 2023 2022 Computers and equipment $ 2,071 $ 2,049 Furniture and fixtures 2,990 2,938 Leasehold improvements 9,692 9,180 Construction-in-progress 169 77 14,922 14,244 Less: Accumulated depreciation (7,443) (5,195) Total property and equipment, net $ 7,479 $ 9,049

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Future Minimum Rental Commitments	The following is a schedule of the future minimum rental commitments for our operating leases reconciled to the lease liability and ROU asset as of December 31, 2023 ( in thousands ): December 31, 2023 2024 $ 6,501 2025 6,673 2026 6,889 2027 7,064 2028 4,781 Thereafter — Total undiscounted future minimum payments 31,908 Present value discount (4,387) Total lease liability 27,521 Unamortized lease incentives (4,591) Cash payments in excess of straight-line lease expense (4,869) Total ROU asset $ 18,061
Schedule of Weighted-average Remaining Lease Term and Discount Rate	The weighted-average remaining lease term and weighted-average discount rate of the Company's operating leases are as follows: December 31, 2023 2022 Weighted-average remaining lease term in years 4.7 5.7 Weighted-average discount rate 6.48 % 6.48 %

DIVESTITURES (Tables)

DIVESTITURES (Tables)	12 Months Ended
	Dec. 31, 2023
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Results, Assets and Liabilities of Discontinued Operations	Results of discontinued operations are as follows ( in thousands ): Year Ended December 31, 2023 2022 2021 Net product sales $ 66,164 $ 102,558 $ 95,654 Total revenue 66,164 102,558 95,654 Operating expenses: Cost of goods sold 1,899 3,172 2,966 Research and development 6,118 8,447 9,169 Selling, general and administrative 19,500 22,686 23,599 Change in fair value of contingent consideration (473) 15,006 22,260 Total operating expenses 27,044 49,311 57,994 Operating income 39,120 53,247 37,660 Other income (expenses), net: Interest expense (191) (261) (459) Gain on disposal of discontinued operations, net of tax 226,005 — — Total other income (expense), net 225,814 (261) (459) Income from discontinued operations before income tax 264,934 52,986 37,201 Income tax on discontinued operations — — — Net income from discontinued operations $ 264,934 $ 52,986 $ 37,201 Assets and liabilities of discontinued operations presented in the Consolidated Balance Sheets as of December 31, 2022 include the following ( in thousands ): December 31, 2022 Assets Current assets: Inventory $ 2,399 Prepaid expenses and other current assets 591 Total current assets of discontinued operations 2,990 Intangible assets, net 47,965 Other assets 377 Total assets of discontinued operations $ 51,332 Liabilities Current liabilities: Business combination-related contingent consideration, current portion $ 7,000 Total current liabilities of discontinued operations 7,000 Business combination-related contingent consideration, less current portion 64,200 Total liabilities of discontinued operations $ 71,200

QUARTERLY FINANCIAL INFORMATI_2

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2023
Quarterly Financial Information Disclosure [Abstract]
Schedule of Consolidated Statements of Operations Data for Each Quarter	The following table presents selected consolidated statements of operations data for each quarter for the fiscal years ended December 31, 2023 and 2022 (unaudited, in thousands, except for per share data) : Quarter First Second Third Fourth For the year ended December 31, 2023: Total revenue $ 30,888 $ 32,196 $ 37,095 $ 45,059 Total operating expenses 128,257 136,147 129,680 139,292 Operating loss (97,369) (103,951) (92,585) (94,233) Loss from continuing operations before income tax provision (96,486) (101,867) (89,229) (88,528) Loss from continuing operations, net of tax (96,564) (101,932) (89,241) (88,596) Income (loss) from discontinued operations, net of tax 1 10,233 16,302 239,976 (1,577) Net (loss) income (86,331) (85,630) 150,735 (90,173) (Loss) income per common share - basic and diluted: Continuing operations $ (1.42) $ (1.34) $ (1.17) $ (1.16) Discontinued operations 0.15 0.21 3.14 (0.02) Net (loss) income per common share $ (1.27) $ (1.13) $ 1.97 $ (1.18) For the year ended December 31, 2022: Total revenue $ 23,412 $ 28,634 $ 28,075 $ 29,339 Total operating expenses 95,393 107,160 110,679 116,041 Operating loss (71,981) (78,526) (82,604) (86,702) Loss from continuing operations before income tax provision (81,694) (79,970) (83,918) (85,573) Loss from continuing operations, net of tax (81,746) (80,023) (84,063) (85,636) Income from discontinued operations, net of tax 1 5,775 12,991 14,407 19,813 Net loss (75,971) (67,032) (69,656) (65,823) (Loss) income per common share - basic and diluted: Continuing operations $ (1.29) $ (1.25) $ (1.31) $ (1.33) Discontinued operations 0.09 0.20 0.22 0.30 Net loss per common share $ (1.20) $ (1.05) $ (1.09) $ (1.03) 1 On August 31, 2023, the Company sold its bile acid business, resulting in a gain, net of tax, of $226.0 million. The Company has reflected the bile acid business as a discontinued operation in the Consolidated Financial Statements for all periods presented. See Note 19 for results of discontinued operations and further discussion.

DESCRIPTION OF BUSINESS (Detail

DESCRIPTION OF BUSINESS (Details) - Disposed of by Sale - Bile Acid Product Portfolio $ in Millions	Aug. 31, 2023 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business	$ 210
Consideration receivable on sale of business (up to)	235
Minimum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Milestone thresholds	125
Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Milestone thresholds	$ 500

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	3 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) segment reporting_unit clinicalTrial	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 01, 2022 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventory valuation reserves		$ 0	$ 2,400,000	$ 0
Total inventory		4,523,000	40,904,000	4,523,000
Cost of goods sold			11,450,000	4,420,000	$ 3,818,000
Loss on allowance for inventory			$ 3,039,000	1,039,000	498,000
Decreased in research and development expenses and related accrued expenses		7,700,000		1,500,000	6,200,000
Number of phase one-half clinical trials in process | clinicalTrial			1
Number of phase 3 clinical trials in process | clinicalTrial			3
Accounts receivable, allowance for credit loss		0	$ 0	0
Number of segments | segment			1
Impairment of intangible assets, finite-lived	$ 3,700,000
Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration]	Selling, General and Administrative Expense
Number of reporting units | reporting_unit			1
Goodwill, impairment			$ 0	0	0
Impairment of intangible assets			0	0	0
Foreign currency transaction gain			(500,000)	(1,400,000)	$ (300,000)
Restructuring costs			11,400,000
Restructuring reserve		0	11,421,000	0
Additional paid-in capital		(1,059,975,000)	(1,327,881,000)	(1,059,975,000)
Reduction in accumulated deficit		$ (1,014,223,000)	(1,125,622,000)	$ (1,014,223,000)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Convertible notes payable						$ 44,700,000
Additional paid-in capital						74,900,000
Reduction in accumulated deficit						$ 30,200,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring and related cost, expected cost			12,000,000
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring and related cost, expected cost			14,000,000
FILSPARI
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Research and development expense			7,500,000
Total inventory			7,200,000
Cost of goods sold			3,200,000
Loss on allowance for inventory			2,100,000
Purchase commitment			$ 1,100,000

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Inventory, Net of Reserves (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Raw materials	$ 33,790	$ 2,397
Work in process	4,727	0
Finished goods	2,387	2,126
Total inventory	40,904	4,523
Inventory, net	9,410	4,523
Long-term inventory, net	$ 31,494	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cost of Goods Sold (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	$ 11,450	$ 4,420	$ 3,818
Cost of goods sold - product sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	8,406	4,420	3,818
Cost of goods sold - license and collaboration
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	$ 3,044	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Vesting Award Terms (Details)	12 Months Ended
	Dec. 31, 2023
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration Term	10 years
Stock Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	3 years
Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	4 years
Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	1 year
Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	4 years

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Major Classifications of Property and Equipment (Details)	Dec. 31, 2023
Computers and equipment
Property, Plant and Equipment [Line Items]
Use life (in years)	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Use life (in years)	7 years

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Foreign Currency Translation Adjustment included in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Foreign Currency Translation Adjustments included in Accumulated Other Comprehensive Loss
Beginning balance	$ 42,851	$ 302,112	$ 211,213
Ending balance	200,810	42,851	302,112
Accumulated Foreign Currency Adjustment Attributable to Parent
Foreign Currency Translation Adjustments included in Accumulated Other Comprehensive Loss
Beginning balance	415	(92)	(1,607)
Foreign currency translation adjustments	(1,871)	507	1,515
Ending balance	$ (1,456)	$ 415	$ (92)

SUMMARY OF SIGNIFICANT ACCOU_10

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Restructuring and Related Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Reserve [Roll Forward]
Liability balance, beginning of period	$ 0
Restructuring expenses	11,394	$ 0	$ 0
Foreign currency impact	27
Liability balance, end of period	$ 11,421	$ 0

REVENUE RECOGNITION - Narrative

REVENUE RECOGNITION - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) pharmacy	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Disaggregation of Revenue [Line Items]
Number of direct-to-patient pharmacies sold to | pharmacy	3
Revenue, performance obligation, description of timing	For FILSPARI, sales are recognized upon delivery of the product to the specialty pharmacies. The Company receives payments from its FILSPARI sales based on terms that are generally 30 days from shipment of the product to the specialty pharmacy. For the Company's other products, product sales are recognized upon delivery to the patient. The Company receives payments from sales of its other products, primarily through third party payers, based on terms that generally are within 30 days of delivery of product to the patient
Revenue increase in performance obligations satisfied in previous period | $	$ 0.4	$ 0.2	$ 0.2
United States | Revenue Benchmark | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	99%

REVENUE RECOGNITION - Net Produ

REVENUE RECOGNITION - Net Product Sales (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total net product sales	$ 45,059	$ 37,095	$ 32,196	$ 30,888	$ 29,339	$ 28,075	$ 28,634	$ 23,412	$ 145,238	$ 109,460	$ 131,836
Net product sales
Disaggregation of Revenue [Line Items]
Total net product sales									127,537	97,970	115,122
Tiopronin products
Disaggregation of Revenue [Line Items]
Total net product sales									98,329	97,970	115,122
FILSPARI
Disaggregation of Revenue [Line Items]
Total net product sales									$ 29,208	$ 0	$ 0

COLLABORATION AND LICENSE AGR_3

COLLABORATION AND LICENSE AGREEMENTS - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended								4 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) performance_obligation	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue		$ 45,059	$ 37,095	$ 32,196	$ 30,888	$ 29,339	$ 28,075	$ 28,634	$ 23,412		$ 145,238	$ 109,460	$ 131,836
Deferred revenue		8,931				22,907				$ 36,647	8,931	22,907	36,647	$ 0
Increase in amortization of deferred revenue											2,900
Deferred revenue, current portion		7,096				11,976					7,096	11,976
License and collaboration revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue											17,701	11,490	$ 16,714
Active Pharmaceutical Ingredient
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue											3,300
Clinical Development Activity
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue											14,400
Vifor Pharma | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment	$ 55,000
Milestone payments (up to)	$ 845,000
Percentage of royalty on net sales receives	40%
Force majeure event period threshold	6 months
Revenue	$ 55,000
Number of performance obligations | performance_obligation	2
Deferred revenue	$ 43,000	8,900				22,900					8,900	22,900
Deferred revenue, current portion		$ 7,100				$ 12,000					$ 7,100	$ 12,000
Vifor Pharma | Collaborative Arrangement | Regulatory and Market Access Milestone
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments (up to)	135,000
Vifor Pharma | Collaborative Arrangement | Sales-based Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments (up to)	$ 655,000
Vifor Pharma | Collaborative Arrangement | License and collaboration revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue										$ 12,000

COLLABORATION AND LICENSE AGR_4

COLLABORATION AND LICENSE AGREEMENTS - Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 22,907	$ 36,647	$ 0
New consideration resulting in deferred revenue	0	0	55,000
Foreign currency impact	387	(2,250)	(1,639)
Ending balance	8,931	22,907	36,647
License and collaboration revenue
Contract with Customer, Liability [Roll Forward]
Contract with customer, liability, revenue recognized	$ (14,363)	$ (11,490)	$ (16,714)

VARIABLE INTEREST ENTITIES (Det

VARIABLE INTEREST ENTITIES (Details) - USD ($) $ in Millions	Mar. 08, 2022	Dec. 31, 2023
PharmaKrysto, LTD | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration agreement payment	$ 0.4
Research and development expenses, estimated	5
Collaborative arrangement, option to purchase additional shares of VIE, amount	1
Collaborative arrangement, option to purchase remaining shares of VIE, amount	5
Milestone payments contingently due	$ 16
Royalty payments, percentage (less than)	4%
Agreement termination notice period		60 days
Percentage of research and development to be funded by the company	100%
PharmaKrysto, LTD
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment to purchase interest in VIE	$ 0.6
Percentage ownership purchased	5%
PharmaKrysto, LTD | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional ownership interest to be purchased upon achievement of certain milestones	5%

MARKETABLE DEBT SECURITIES - Ma

MARKETABLE DEBT SECURITIES - Marketable Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Total available-for-sale marketable debt securities	$ 508,675	$ 388,557
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Total available-for-sale marketable debt securities	34,458	123,647
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Total available-for-sale marketable debt securities	368,323	224,055
Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Total available-for-sale marketable debt securities	$ 105,894	$ 40,855

MARKETABLE DEBT SECURITIES - Sh

MARKETABLE DEBT SECURITIES - Short-term Marketable Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Marketable debt securities, available-for-sale, amortized cost, current	$ 249,247	$ 287,615
Marketable debt securities, available-for-sale, unrealized gains, current	90	2
Marketable debt securities, available-for-sale, unrealized losses, current	(699)	(2,091)
Marketable debt securities, available-for-sale, current	248,638	285,526
Marketable debt securities, available-for-sale, amortized cost, noncurrent	258,687	103,897
Marketable debt securities, available-for-sale, unrealized gains, noncurrent	1,550	39
Marketable debt securities, available-for-sale, unrealized losses, noncurrent	(200)	(905)
Marketable debt securities, available-for-sale, noncurrent	260,037	103,031
Marketable debt securities, available-for-sale, amortized cost	507,934	391,512
Marketable debt securities, available-for-sale, accumulated gross unrealized gains, before tax	1,640	41
Marketable debt securities, available-for-sale, accumulated gross unrealized losses, before tax	(899)	(2,996)
Marketable debt securities, available-for-sale	508,675	388,557
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Marketable debt securities, available-for-sale, amortized cost, current	34,450	124,301
Marketable debt securities, available-for-sale, unrealized gains, current	25	2
Marketable debt securities, available-for-sale, unrealized losses, current	(17)	(656)
Marketable debt securities, available-for-sale, current	34,458	123,647
Marketable debt securities, available-for-sale	34,458	123,647
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Marketable debt securities, available-for-sale, amortized cost, current	133,463	155,841
Marketable debt securities, available-for-sale, unrealized gains, current	29	0
Marketable debt securities, available-for-sale, unrealized losses, current	(408)	(1,355)
Marketable debt securities, available-for-sale, current	133,084	154,486
Marketable debt securities, available-for-sale, amortized cost, noncurrent	233,969	70,195
Marketable debt securities, available-for-sale, unrealized gains, noncurrent	1,444	33
Marketable debt securities, available-for-sale, unrealized losses, noncurrent	(174)	(659)
Marketable debt securities, available-for-sale, noncurrent	235,239	69,569
Marketable debt securities, available-for-sale	368,323	224,055
Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Marketable debt securities, available-for-sale, amortized cost, current	81,334	7,473
Marketable debt securities, available-for-sale, unrealized gains, current	36	0
Marketable debt securities, available-for-sale, unrealized losses, current	(274)	(80)
Marketable debt securities, available-for-sale, current	81,096	7,393
Marketable debt securities, available-for-sale, amortized cost, noncurrent	24,718	33,702
Marketable debt securities, available-for-sale, unrealized gains, noncurrent	106	6
Marketable debt securities, available-for-sale, unrealized losses, noncurrent	(26)	(246)
Marketable debt securities, available-for-sale, noncurrent	24,798	33,462
Marketable debt securities, available-for-sale	$ 105,894	$ 40,855

MARKETABLE DEBT SECURITIES - Na

MARKETABLE DEBT SECURITIES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Accrued interest receivable	$ 4.6	$ 1.9
Available-for-sale marketable debt securities in an unrealized loss position	$ 269.7	$ 363.7

MARKETABLE DEBT SECURITIES - De

MARKETABLE DEBT SECURITIES - Debt Securities in Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 227,533	$ 248,321
Less than 12 months, unrealized losses	639	1,960
12 months or greater, fair value	41,315	112,420
12 months or greater, unrealized losses	260	1,036
Total, fair value	268,848	360,741
Total, unrealized losses	899	2,996
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	24,798	117,853
Less than 12 months, unrealized losses	17	656
12 months or greater, fair value	0	0
12 months or greater, unrealized losses	0	0
Total, fair value	24,798	117,853
Total, unrealized losses	17	656
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	140,802	99,066
Less than 12 months, unrealized losses	405	1,041
12 months or greater, fair value	28,775	107,964
12 months or greater, unrealized losses	177	973
Total, fair value	169,577	207,030
Total, unrealized losses	582	2,014
Securities of government-sponsored entities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	61,933	31,402
Less than 12 months, unrealized losses	217	263
12 months or greater, fair value	12,540	4,456
12 months or greater, unrealized losses	83	63
Total, fair value	74,473	35,858
Total, unrealized losses	$ 300	$ 326

CONVERTIBLE NOTES PAYABLE - Con

CONVERTIBLE NOTES PAYABLE - Convertible Senior Notes (Details) - Senior Notes - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total convertible senior notes, net of unamortized debt discount and debt issuance costs	$ 377,263	$ 375,545
Senior Notes Due 2029
Debt Instrument [Line Items]
Interest rate percentage	2.25%
Convertible senior notes	$ 316,250	316,250
Unamortized debt issuance costs	$ (7,348)	(8,750)
Senior Notes Due 2025
Debt Instrument [Line Items]
Interest rate percentage	2.50%
Convertible senior notes	$ 68,904	68,904
Unamortized debt issuance costs	$ (543)	$ (859)

CONVERTIBLE NOTES PAYABLE - Nar

CONVERTIBLE NOTES PAYABLE - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Mar. 11, 2022 USD ($)	Sep. 10, 2018 USD ($)	Dec. 31, 2023 USD ($) day $ / shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Debt instrument, repurchase amount Including accrued and unpaid interest	$ 213,800
Loss on extinguishment of debt			$ 0	$ 7,578	$ 0
Write off of deferred debt financing costs			3,400
Interest expense			$ 11,300	$ 11,000	$ 19,700
Senior Notes Due 2029 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, excluding current maturities	316,300
Interest rate percentage			2.25%
Proceeds from issuance of debt	306,400
Debt issuance costs, net	9,900
Accrued interest			$ 2,400
Debt instrument, convertible, threshold percentage of stock price trigger			130%
Debt instrument, convertible, conversion ratio			0.001374
Debt instrument, convertible, conversion price (in dollars per share) | $ / shares			$ 31.87
Notes payable			$ 100,000
Long-term debt, term			7 years
Debt instrument, interest rate, effective percentage			2.74%
Debt Instrument, Convertible, Redemption Option, Scheduled Trading Days Prior To Maturity Date | day			40
Senior Notes Due 2029 | Senior Notes | Debt Conversion, Scenario One
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days | day			20
Debt instrument, convertible, threshold consecutive trading days | day			30
Debt instrument, convertible, threshold percentage of stock price trigger			130%
Senior Notes Due 2029 | Senior Notes | Debt Conversion, Scenario Two
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days | day			5
Debt instrument, convertible, threshold consecutive trading days | day			10
Debt instrument, convertible, threshold percentage of stock price trigger			98%
Senior Notes Due 2029, Issued Pursuant To Underwriters Option | Senior Notes
Debt Instrument [Line Items]
Long-term debt, excluding current maturities	41,300
Senior Notes Due 2025 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, excluding current maturities		$ 276,000
Interest rate percentage			2.50%
Proceeds from issuance of debt		267,200
Debt issuance costs, net		$ 8,800
Accrued interest			$ 500
Debt instrument, convertible, threshold percentage of stock price trigger			130%
Debt instrument, convertible, conversion ratio			0.0257739
Debt instrument, convertible, conversion price (in dollars per share) | $ / shares			$ 38.80
Long-term debt, term			7 years
Debt instrument, interest rate, effective percentage			2.98%
Debt instrument, repurchase amount	$ 207,100
Long-term debt, excluding current maturities, repaid if converted			$ 68,900
Senior Notes Due 2025 | Senior Notes | Debt Conversion, Scenario One
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days | day			20
Debt instrument, convertible, threshold consecutive trading days | day			30
Debt instrument, convertible, threshold percentage of stock price trigger			130%
Senior Notes Due 2025 | Senior Notes | Debt Conversion, Scenario Two
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days | day			5
Debt instrument, convertible, threshold consecutive trading days | day			10
Debt instrument, convertible, threshold percentage of stock price trigger			98%

CONVERTIBLE NOTES PAYABLE - Int

CONVERTIBLE NOTES PAYABLE - Interest Expense Recognized (Details) - Senior Notes Due 2025 and Senior Notes Due 2029 - Senior Notes - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Contractual interest expense	$ 8,838	$ 8,433	$ 6,900
Amortization of debt discount	0	0	10,339
Amortization of debt issuance costs	1,718	1,622	903
Total interest expense for the 2025 and 2029 Notes	$ 10,556	$ 10,055	$ 18,142

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) - Senior Notes - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate percentage	2.50%
Fair value of convertible debt	$ 58.3	$ 62.9
Senior Notes Due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate percentage	2.25%
Fair value of convertible debt	$ 212.1	$ 283

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Cash and Cash Equivalents	$ 58,176	$ 61,688
Marketable debt securities, available-for-sale	508,675	388,557
Total	566,851	450,245
Quoted prices in active markets (Level 1)
Assets:
Cash and Cash Equivalents	58,176	61,688
Marketable debt securities, available-for-sale	0	0
Total	58,176	61,688
Significant other observable inputs (Level 2)
Assets:
Cash and Cash Equivalents	0	0
Marketable debt securities, available-for-sale	508,675	388,557
Total	508,675	388,557
Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	0	0
Marketable debt securities, available-for-sale	0	0
Total	$ 0	$ 0

INTANGIBLE ASSETS - Narrative (

INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Mar. 31, 2022	Nov. 30, 2018	Nov. 30, 2017	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Payments to date under terms of licensing agreement				$ 41,591	$ 28,366	$ 19,050
Gross Carrying Amount				183,037	158,783
Amortization expense				36,282	18,603	$ 11,046
Goodwill				800	$ 800
Ligand license
Finite-Lived Intangible Assets [Line Items]
License agreement, milestone payments				$ 114,100
License agreement, milestone payment, milestone one	$ 23,000
Useful Life				11 years	11 years
Gross Carrying Amount				$ 27,448	$ 19,400
Ligand license | Minimum
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage				15%
Ligand license | Maximum
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage				17%
Royalty Agreements
Finite-Lived Intangible Assets [Line Items]
Payments to date under terms of licensing agreement				$ 4,400
Thiola license
Finite-Lived Intangible Assets [Line Items]
Useful Life				12 years	12 years		10 years
Automatic renewal periods							1 year
Licensing agreement, extension term			5 years
Gross Carrying Amount			$ 5,900	$ 155,589	$ 139,383
Payments for the option to acquire business		$ 300
Payment of guaranteed minimum royalty		$ 100
Minimum royalty, percentage		20%
Amortization expense		$ 1,000
Guaranteed minimum liability		$ 700
Increase in intangible assets				$ 16,200
Thiola license | Mission Pharmacal Company
Finite-Lived Intangible Assets [Line Items]
Annual royalty percentage				20%
Finite lived intangible asset upfront fee				$ 3,000
Royalty guarantees, commitments, amount				2,000
Accrued royalties				9,700	11,100
Thiola license | Mission Pharmacal Company | Other Current Liabilities
Finite-Lived Intangible Assets [Line Items]
Royalty guarantees, commitments, amount				2,100	2,100
Thiola license | Mission Pharmacal Company | Other Noncurrent Liabilities
Finite-Lived Intangible Assets [Line Items]
Royalty guarantees, commitments, amount				$ 7,600	$ 9,000
Thiola license | Minimum | Mission Pharmacal Company
Finite-Lived Intangible Assets [Line Items]
Discount rate				7%
Thiola license | Maximum | Mission Pharmacal Company
Finite-Lived Intangible Assets [Line Items]
Discount rate				11%

INTANGIBLE ASSETS - Amortizable

INTANGIBLE ASSETS - Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Nov. 30, 2017	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 183,037	$ 158,783
Accumulated Amortization	(79,347)	(62,463)
Intangible assets finite-lived, net	$ 103,690	$ 96,320
Thiola license
Finite-Lived Intangible Assets [Line Items]
Useful Life	12 years	12 years		10 years
Gross Carrying Amount	$ 155,589	$ 139,383	$ 5,900
Accumulated Amortization	(77,311)	(50,324)
Intangible assets finite-lived, net	$ 78,278	$ 89,059
Ligand license
Finite-Lived Intangible Assets [Line Items]
Useful Life	11 years	11 years
Gross Carrying Amount	$ 27,448	$ 19,400
Accumulated Amortization	(2,036)	(12,139)
Intangible assets finite-lived, net	$ 25,412	$ 7,261

INTANGIBLE ASSETS - Amortizatio

INTANGIBLE ASSETS - Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 36,282	$ 18,603	$ 11,046
Selling, general and administrative
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	29,021	12,339	9,888
Research and development
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 7,261	$ 6,264	$ 1,158

INTANGIBLE ASSETS - Amortizat_2

INTANGIBLE ASSETS - Amortization Expense for Next Five Years (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
2024	$ 37,625
2025	40,709
2026	8,347
2027	2,722
2028	2,729
Thereafter	11,558
Intangible assets finite-lived, net	$ 103,690	$ 96,320

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Compensation related costs	$ 29,908	$ 35,267
Research and development	26,006	26,070
Sales discounts, rebates, and allowances	13,730	13,486
Transition services accrual	12,282	0
Accrued restructuring costs	11,421	0
Selling, general and administrative	7,190	8,791
Accrued royalties	6,991	7,755
Miscellaneous accrued	11,463	4,373
Total accrued expenses	$ 118,991	$ 95,742

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Nov. 30, 2020
Business Acquisition [Line Items]
Contractual obligation, to be paid, next 12 months	$ 50
Orphan Technologies Limited
Business Acquisition [Line Items]
Contingent consideration, liability		$ 427

STOCKHOLDERS_ EQUITY - Common S

STOCKHOLDERS’ EQUITY - Common Stock and Preferred Stock (Details)	12 Months Ended
	Dec. 31, 2023 vote $ / shares shares	Dec. 31, 2022 $ / shares shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Number of votes per common share owned | vote	1
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares issued (in shares)	0	0
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	1,000

STOCKHOLDERS_ EQUITY - 2018 Equ

STOCKHOLDERS’ EQUITY - 2018 Equity Incentive Plan (Details) shares in Millions	12 Months Ended
	Dec. 31, 2023 shares
2018 Equity Incentive Plan and Prior Plans
Class of Stock [Line Items]
Shares remaining available for issuance under the plan (in shares)	15.7
2018 Equity Incentive Plan
Class of Stock [Line Items]
Shares remaining available for issuance under the plan (in shares)	4.5
Expiration Term	10 years
Vesting Term	4 years

STOCKHOLDERS_ EQUITY - 2017 Emp

STOCKHOLDERS’ EQUITY - 2017 Employee Stock Purchase Plan (Details) - 2017 ESPP - USD ($)	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares remaining available for issuance under the plan (in shares)	2,180,000	380,000
Potential increase in shares available for issuance, as a percent of total outstanding common stock	1%
Maximum number of additional shares authorized for issuance (in shares)	300,000
Purchase price of common stock, percent of fair market value	85%
Stock purchase offering period	6 months
Employee stock purchase plan, maximum compensation	15%
Employee stock purchase plan annual limit	$ 25,000
Shares reserved for future issuance (in shares)	1,100,657

STOCKHOLDERS_ EQUITY - Assumpti

STOCKHOLDERS’ EQUITY - Assumptions used in Black-scholes Options Pricing Model (Details) - Stock Options	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free rate	3.90%	1.70%	0.60%
Expected volatility	50%	50%	59%
Expected life (in years)	6 years 4 months 24 days	6 years 4 months 24 days	6 years 4 months 24 days
Expected dividend yield	0%	0%	0%

STOCKHOLDERS_ EQUITY - Share-ba

STOCKHOLDERS’ EQUITY - Share-based Compensation, Stock Options, Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Exercised, aggregate intrinsic value	$ 1,422
Shares underlying options (in shares)	7,942,964	6,999,669	6,011,349
Weighted Average, exercise price (in dollars per share)	$ 20.85	$ 20.22	$ 19.34
Weighted Average, remaining contractual term (in years)	3 years 11 months 12 days	4 years 7 months 13 days	5 years 1 month 28 days
Aggregate intrinsic value	$ 0	$ 21,806	$ 71,063
Closing stock price of stock options outstanding and exercisable (in dollars per share)	$ 8.99	$ 21.03	$ 31.04
Stock Options
Shares Underlying Options
Outstanding, beginning balance (in shares)	9,932,422
Granted (in shares)	1,157,750
Forfeited and expired (in shares)	(652,156)
Exercised (in shares)	(226,663)
Outstanding, ending balance (in shares)	10,211,353	9,932,422
Vested and expected to vest (in shares)	10,211,353
Weighted Average, Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 21.56
Granted (in dollars per share)	21.69
Forfeited and expired (in dollars per share)	24.98
Exercised (in dollars per share)	14.30
Outstanding, ending balance (in dollars per share)	21.52	$ 21.56
Vested and expected to vest (in dollars per share)	$ 21.52
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average, remaining contractual life (in years)	4 years 10 months 28 days	5 years 9 months 14 days
Vested and expected to vest (in years)	4 years 10 months 17 days
Aggregate intrinsic value, beginning balance	$ 24,658
Exercised, aggregate intrinsic value	1,400	$ 5,100	$ 7,500
Aggregate intrinsic value, ending balance	0	$ 24,658
Vested and expected to vest, aggregate intrinsic value	$ 0
Weighted average grant date fair value of options (in dollars per share)	$ 11.66	$ 13.45	$ 14
Compensation expense not yet recognized, stock options	$ 24,100
Weighted average remaining vesting period (in years)	2 years 3 months 18 days
Stock Options | Chief Financial Officer
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Modification expense	$ 2,600

STOCKHOLDERS_ EQUITY - Restrict

STOCKHOLDERS’ EQUITY - Restricted Stock Unit Activity (Details) - Restricted Stock Units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to RSU's granted	$ 46.8
Weighted average period for unrecognized costs (in years)	2 years 6 months
Number of RSUs
Unvested beginning balance (in shares)	2,343,709
Granted (in shares)	1,907,542
Vested (in shares)	(803,113)
Forfeited/cancelled (in shares)	(574,092)
Unvested ending balance (in shares)	2,874,046	2,343,709
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share)	$ 24.65
Granted (in dollars per share)	21.20
Vested (in dollars per share)	23.30	$ 21.21	$ 18.08
Forfeited/cancelled (in dollars per share)	23.48
Unvested ending balance (in dollars per share)	$ 22.97	$ 24.65
Fair value of restricted stock units vested	$ 18.7	$ 11.5	$ 7.4

STOCKHOLDERS_ EQUITY - Performa

STOCKHOLDERS’ EQUITY - Performance-based Stock Unit Activity (Details) - Performance Shares - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to PSU's granted	$ 2
Weighted average period for unrecognized costs (in years)	10 months 24 days
Number of PSUs
Unvested beginning balance (in shares)	157,048
Granted (in shares)	66,250
Vested (in shares)	(16,500)
Forfeited/cancelled (in shares)	(31,340)
Unvested ending balance (in shares)	175,458	157,048
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share)	$ 25.24
Granted (in dollars per share)	22.40
Vested (in dollars per share)	15.46	$ 25.26	$ 15.46
Forfeited/cancelled (in dollars per share)	22.31
Unvested ending balance (in dollars per share)	$ 25.61	$ 25.24
Fair value of performance-based stock units vested	$ 0.3	$ 0.4	$ 1.8

STOCKHOLDERS_ EQUITY - Non-cash

STOCKHOLDERS’ EQUITY - Non-cash Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 44,246	$ 38,143	$ 29,566
Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	27,111	24,368	17,009
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 17,135	$ 13,775	$ 12,557

NET LOSS PER COMMON SHARE - Nar

NET LOSS PER COMMON SHARE - Narrative (Details) - Underwritten Equity Offering - $ / shares	Feb. 28, 2023	Feb. 28, 2021
Subsidiary, Sale of Stock [Line Items]
Sales price per share (in dollars per share)	$ 21	$ 26.75
Common Stock
Subsidiary, Sale of Stock [Line Items]
Pre-funded warrants exercisable for share of common stock (in shares)	1
Pre Funded Warrant
Subsidiary, Sale of Stock [Line Items]
Number of common stock called by warrants (in shares)	1,250,000
Sales price per share (in dollars per share)	$ 20.9999
Exercise price of each pre-funded warrant (in dollars per share)	$ 0.0001

NET LOSS PER COMMON SHARE - Bas

NET LOSS PER COMMON SHARE - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Continuing operations, basic (in shares)									74,267,418	63,758,515	59,832,287
Continuing operations, diluted (in shares)									74,267,418	63,758,515	59,832,287
Discontinued operations, basic (in shares)									74,267,418	63,758,515	59,832,287
Discontinued Operations, diluted (in shares)									74,267,418	63,758,515	59,832,287
Weighted average common shares outstanding, basic (in shares)									74,267,418	63,758,515	59,832,287
Weighted average common shares outstanding, diluted (in shares)									74,267,418	63,758,515	59,832,287
Net loss from continuing operations	$ (88,596)	$ (89,241)	$ (101,932)	$ (96,564)	$ (85,636)	$ (84,063)	$ (80,023)	$ (81,746)	$ (376,333)	$ (331,468)	$ (217,292)
Income from discontinued operations, net of tax	$ (1,577)	$ 239,976	$ 16,302	$ 10,233	$ 19,813	$ 14,407	$ 12,991	$ 5,775	264,934	52,986	37,201
Net loss, basic									(111,399)	(278,482)	(180,091)
Net loss, diluted									$ (111,399)	$ (278,482)	$ (180,091)
Net loss from continuing operations, basic (in dollars per share)	$ (1.16)	$ (1.17)	$ (1.34)	$ (1.42)	$ (1.33)	$ (1.31)	$ (1.25)	$ (1.29)	$ (5.07)	$ (5.20)	$ (3.63)
Net loss from continuing operations, diluted (in dollars per share)	(1.16)	(1.17)	(1.34)	(1.42)	(1.33)	(1.31)	(1.25)	(1.29)	(5.07)	(5.20)	(3.63)
Net income from discontinued operations, basic (in dollars per share)	(0.02)	3.14	0.21	0.15	0.30	0.22	0.20	0.09	3.57	0.83	0.62
Net income from discontinued operations, diluted (in dollars per share)	(0.02)	3.14	0.21	0.15	0.30	0.22	0.20	0.09	3.57	0.83	0.62
Net income (loss) per common share, diluted (in dollars per share)	(1.18)	1.97	(1.13)	(1.27)	(1.03)	(1.09)	(1.05)	(1.20)	(1.50)	(4.37)	(3.01)
Net income (loss) per common share, basic (in dollars per share)	$ (1.18)	$ 1.97	$ (1.13)	$ (1.27)	$ (1.03)	$ (1.09)	$ (1.05)	$ (1.20)	$ (1.50)	$ (4.37)	$ (3.01)

NET LOSS PER COMMON SHARE - Ant

NET LOSS PER COMMON SHARE - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive shares	25,670,747	23,085,349	17,897,060
Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive shares	11,697,952	10,869,000	7,113,402
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive shares	10,555,550	10,041,249	9,214,188
Restricted stock units and performance-based stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive shares	3,417,245	2,175,100	1,569,470

INCOME TAXES - Net Loss from Co

INCOME TAXES - Net Loss from Continuing Operations Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Total	$ (88,528)	$ (89,229)	$ (101,867)	$ (96,486)	$ (85,573)	$ (83,918)	$ (79,970)	$ (81,694)	$ (376,110)	$ (331,155)	$ (216,883)
United States
Operating Loss Carryforwards [Line Items]
Total									(293,283)	(268,887)	(161,333)
Foreign
Operating Loss Carryforwards [Line Items]
Total									$ (82,827)	$ (62,268)	$ (55,550)

INCOME TAXES - Components of Pr

INCOME TAXES - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current
Federal	$ 0	$ 0	$ 0
State	223	314	412
Foreign	0	(1)	(3)
Total	223	313	409
Deferred
Federal	0	0	0
State	0	0	0
Total	0	0	0
Total tax provision	$ 223	$ 313	$ 409

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Statutory Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Statutory rate - federal	(21.00%)	(21.00%)	(21.00%)
State taxes, net of federal benefit	(3.19%)	(3.62%)	(2.92%)
Foreign rate differential	1.29%	0.81%	2.72%
Nondeductible executive compensation	1.50%	0.41%	0.40%
Excess tax benefits associated with share-based awards	0.68%	(0.17%)	0.15%
Other permanent differences	0.37%	0.17%	0.12%
Tax credits	(1.13%)	(5.29%)	(8.65%)
Return to provision adjustments and other true-ups	4.19%	(0.17%)	2%
Adoption of ASU 2020-06	0%	(3.54%)	0%
Other	0.57%	0%	0.18%
Change in valuation allowance	16.78%	32.49%	27.19%
Income tax provision (benefit)	0.06%	0.09%	0.19%

INCOME TAXES - Deferred Tax Ass

INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets:
Net operating loss	$ 81,531	$ 49,811
Research and development and other tax credits	77,555	91,052
Capitalized research and development	39,907	36,442
Contingent consideration	0	18,124
Other accrued expenses	13,187	13,247
Stock based compensation	21,607	22,936
Charitable contributions	6,110	4,781
Intangible assets greater than book	47,731	51,391
Interest expense limitation	1,679	4,346
Operating lease liabilities	6,812	8,018
Tax basis depreciation greater than book depreciation	292	105
Difference in basis of loan costs	62	15
Deferred tax assets	296,473	300,268
Deferred Tax Liabilities:
Operating lease right of use assets	(5,595)	(6,658)
Prepaid assets	(198)	(206)
Deferred tax liabilities	(5,793)	(6,864)
Net deferred tax assets before valuation allowance	290,680	293,404
Valuation allowance	(290,680)	(293,404)
Total deferred tax assets	$ 0	$ 0

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 290,680,000	$ 293,404,000
Increase (decrease) in valuation allowance	(2,700,000)	95,100,000
Unrecognized tax benefits	22,906,000	11,490,000	$ 7,825,000
Unrecognized tax benefits that would impact effective tax rate	22,900,000
Income tax examination, penalties and interest expense	0	$ 100,000	$ 100,000
Unrecognized Tax Benefits
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance	22,900,000
Interest Expense Limitation Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	8,000,000
Federal Orphan Drug Tax Credit
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	86,800,000
Tax Competes Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	2,000,000
United States
Operating Loss Carryforwards [Line Items]
Available unused NOL carryforwards	154,300,000
United States | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	4,800,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Available unused NOL carryforwards	208,400,000
Operating loss carryforwards, indefinite carryforward period	39,800,000
State and Local Jurisdiction | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, finite carryforward period, amount	8,000,000
Tax credit carryforward, indefinite carryforward period, amount	1,300,000
Foreign | Irish
Operating Loss Carryforwards [Line Items]
Available unused NOL carryforwards	16,100,000
Foreign | Swiss
Operating Loss Carryforwards [Line Items]
Available unused NOL carryforwards	251,100,000
Tax credit carryforward	$ 526,200,000

INCOME TAXES - Unrecognized Tax

INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 11,490	$ 7,825
Increase in current period positions	4,871	2,056
Increase in prior period positions	7,383	1,919
Decrease in prior period positions	(838)	0
Decrease due to settlements with tax authorities	0	(310)
Ending balance	$ 22,906	$ 11,490

EQUITY OFFERINGS (Details)

EQUITY OFFERINGS (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended			35 Months Ended
	Feb. 28, 2023	Feb. 28, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Feb. 29, 2020
Class of Stock [Line Items]
Proceeds from the issuance of common stock, net of issuance costs			$ 191,198		$ 189,278	$ 0
Proceeds from the issuance of pre-funded warrants, net of issuance costs			$ 24,630		$ 0	$ 0
Underwritten Equity Offering
Class of Stock [Line Items]
Shares sold (in shares)	9,700,000	7,500,000
Sales price per share (in dollars per share)	$ 21	$ 26.75
Proceeds from the issuance of common stock, net of issuance costs	$ 215,800	$ 189,300
Underwritten Equity Offering | Common Stock
Class of Stock [Line Items]
Prefunded warrants, notice period for modifying limitations	61 days
Pre-funded warrants exercisable for share of common stock (in shares)	1
Underwritten Equity Offering | Pre Funded Warrant
Class of Stock [Line Items]
Number of common stock called by warrants (in shares)	1,250,000
Sales price per share (in dollars per share)	$ 20.9999
Exercise price of each pre-funded warrant (in dollars per share)	$ 0.0001
Proceeds from the issuance of pre-funded warrants, net of issuance costs	$ 24,600
At-The-Market Offering
Class of Stock [Line Items]
Shares sold (in shares)			0
Proceeds from the issuance of common stock, net of issuance costs				$ 20,100
Aggregate offering amount authorized							$ 100,000
At-the-market equity offering program, remaining offering amount authorized			$ 19,500
At-The-Market Offering Under Previous Registration Statement
Class of Stock [Line Items]
At-the-market equity offering program, amount sold to date			28,600
At-The-Market Offering Under Current Registration Statement
Class of Stock [Line Items]
At-the-market equity offering program, amount sold to date			$ 51,900

RETIREMENT PLAN (Details)

RETIREMENT PLAN (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Plan Assets, Category [Line Items]
Defined contribution plan, employer contributions	$ 2.7	$ 2.1	$ 1.3
Switzerland Defined Benefit Plan
Defined Benefit Plan, Plan Assets, Category [Line Items]
Benefit obligation	3.3
Plan assets	$ 2.5

PROPERTY AND EQUIPMENT (Details

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 14,922	$ 14,244
Less: Accumulated depreciation	(7,443)	(5,195)
Total property and equipment, net	7,479	9,049
Depreciation expense	2,200	2,100	$ 1,700
Computers and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,071	2,049
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,990	2,938
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,692	9,180
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 169	$ 77

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) lease	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right of use assets	$ 18,061	$ 21,000
Total lease liability	27,521
Operating lease expense	$ 4,900	$ 5,000	$ 4,900
Office Lease 2020
Lessee, Lease, Description [Line Items]
Operating lease right of use assets				$ 34,600
Total lease liability				34,500
Tenant improvement allowance				$ 7,900
Operating lease extension term	5 years
Kilroy Realty, L.P.
Lessee, Lease, Description [Line Items]
Number of operating leases | lease	2
Esprit Investments Limited
Lessee, Lease, Description [Line Items]
Number of operating leases | lease	1
Operating lease right of use assets	$ 400
Total lease liability	$ 400
Operating lease extension term	5 years

LEASES - Future Minimum Rental

LEASES - Future Minimum Rental Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 6,501
2025	6,673
2026	6,889
2027	7,064
2028	4,781
Thereafter	0
Total undiscounted future minimum payments	31,908
Present value discount	(4,387)
Total lease liability	27,521
Unamortized lease incentives	(4,591)
Cash payments in excess of straight-line lease expense	(4,869)
Total ROU asset	$ 18,061	$ 21,000

LEASES - Weighted-average Remai

LEASES - Weighted-average Remaining Lease Term and Discount Rate (Details)	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted-average remaining lease term in years	4 years 8 months 12 days	5 years 8 months 12 days
Weighted-average discount rate	6.48%	6.48%

DIVESTITURES - Additional Infor

DIVESTITURES - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transition services accrual		$ 12,282	$ 0
Disposed of by Sale | Bile Acid Product Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of business	$ 210,000
Consideration receivable on sale of business (up to)	235,000
Gain on disposal of discontinued operations, net of tax	$ 226,000	226,005	$ 0	$ 0
Discontinued operation after disposal, expense		1,000
Contingent consideration received on sale of business		$ 600
Period of continuing involvement after disposal	12 months
Disposed of by Sale | Bile Acid Product Portfolio | Minimum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Milestone thresholds	$ 125,000
Disposed of by Sale | Bile Acid Product Portfolio | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Milestone thresholds	$ 500,000

DIVESTITURES - Results of Disco

DIVESTITURES - Results of Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net income from discontinued operations		$ (1,577)	$ 239,976	$ 16,302	$ 10,233	$ 19,813	$ 14,407	$ 12,991	$ 5,775	$ 264,934	$ 52,986	$ 37,201
Disposed of by Sale | Bile Acid Product Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue										66,164	102,558	95,654
Cost of goods sold										1,899	3,172	2,966
Research and development										6,118	8,447	9,169
Selling, general and administrative										19,500	22,686	23,599
Change in fair value of contingent consideration										(473)	15,006	22,260
Total operating expenses										27,044	49,311	57,994
Operating income										39,120	53,247	37,660
Interest expense										(191)	(261)	(459)
Gain on disposal of discontinued operations, net of tax	$ 226,000									226,005	0	0
Total other income (expense), net										225,814	(261)	(459)
Income from discontinued operations before income tax										264,934	52,986	37,201
Income tax on discontinued operations										0	0	0
Net income from discontinued operations										264,934	52,986	37,201
Net product sales | Disposed of by Sale | Bile Acid Product Portfolio
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue										$ 66,164	$ 102,558	$ 95,654

DIVESTITURES - Assets and Liabi

DIVESTITURES - Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Total current assets of discontinued operations	$ 0	$ 2,990
Current liabilities:
Total current liabilities of discontinued operations	$ 0	7,000
Disposed of by Sale | Bile Acid Product Portfolio
Current assets:
Inventory		2,399
Prepaid expenses and other current assets		591
Total current assets of discontinued operations		2,990
Intangible assets, net		47,965
Other assets		377
Total assets of discontinued operations		51,332
Current liabilities:
Business combination-related contingent consideration, current portion		7,000
Total current liabilities of discontinued operations		7,000
Business combination-related contingent consideration, less current portion		64,200
Total liabilities of discontinued operations		$ 71,200

QUARTERLY FINANCIAL INFORMATI_3

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Total revenue		$ 45,059	$ 37,095	$ 32,196	$ 30,888	$ 29,339	$ 28,075	$ 28,634	$ 23,412	$ 145,238	$ 109,460	$ 131,836
Total operating expenses		139,292	129,680	136,147	128,257	116,041	110,679	107,160	95,393	533,376	429,273	331,261
Operating loss		(94,233)	(92,585)	(103,951)	(97,369)	(86,702)	(82,604)	(78,526)	(71,981)	(388,138)	(319,813)	(199,425)
Loss from continuing operations before income tax provision		(88,528)	(89,229)	(101,867)	(96,486)	(85,573)	(83,918)	(79,970)	(81,694)	(376,110)	(331,155)	(216,883)
Loss from continuing operations, net of tax		(88,596)	(89,241)	(101,932)	(96,564)	(85,636)	(84,063)	(80,023)	(81,746)	(376,333)	(331,468)	(217,292)
Income (loss) from discontinued operations, net of tax		(1,577)	239,976	16,302	10,233	19,813	14,407	12,991	5,775	264,934	52,986	37,201
Net loss		$ (90,173)	$ 150,735	$ (85,630)	$ (86,331)	$ (65,823)	$ (69,656)	$ (67,032)	$ (75,971)	$ (111,399)	$ (278,482)	$ (180,091)
(Loss) income per common share - basic and diluted:
Continuing operations - basic (in dollars per share)		$ (1.16)	$ (1.17)	$ (1.34)	$ (1.42)	$ (1.33)	$ (1.31)	$ (1.25)	$ (1.29)	$ (5.07)	$ (5.20)	$ (3.63)
Continuing operations, diluted (in dollars per share)		(1.16)	(1.17)	(1.34)	(1.42)	(1.33)	(1.31)	(1.25)	(1.29)	(5.07)	(5.20)	(3.63)
Discontinued operations, basic (in dollars per share)		(0.02)	3.14	0.21	0.15	0.30	0.22	0.20	0.09	3.57	0.83	0.62
Discontinued operations, diluted (in dollars per share)		(0.02)	3.14	0.21	0.15	0.30	0.22	0.20	0.09	3.57	0.83	0.62
Net income (loss) per common share, basic (in dollars per share)		(1.18)	1.97	(1.13)	(1.27)	(1.03)	(1.09)	(1.05)	(1.20)	(1.50)	(4.37)	(3.01)
Net income (loss) per common share, diluted (in dollars per share)		$ (1.18)	$ 1.97	$ (1.13)	$ (1.27)	$ (1.03)	$ (1.09)	$ (1.05)	$ (1.20)	$ (1.50)	$ (4.37)	$ (3.01)
Disposed of by Sale | Bile Acid Product Portfolio
Quarterly Financial Information Disclosure [Abstract]
Income (loss) from discontinued operations, net of tax										$ 264,934	$ 52,986	$ 37,201
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal of discontinued operations, net of tax	$ 226,000									$ 226,005	$ 0	$ 0

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) $ in Millions	Jan. 25, 2024 USD ($)
Renalys Pharma, Inc | Regulatory, Development And Sales-based Milestone | Subsequent Event | Collaborative Arrangement
Subsequent Event [Line Items]
Milestone payments (up to)	$ 120