Mirum Pharmaceuticals (MIRM) 10-K 15 Mar 24 2023 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Mar. 08, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Registrant Name	Mirum Pharmaceuticals, Inc.
Entity Central Index Key	0001759425
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
ICFR Auditor Attestation Flag	true
Entity Public Float			$ 830.1
Entity Common Stock, Shares Outstanding		47,003,329
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity File Number	001-38981
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-1281555
Entity Address, Address Line One	950 Tower Lane, Suite 1050
Entity Address, City or Town	Foster City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94404
City Area Code	650
Local Phone Number	667-4085
Document Transition Report	false
Document Annual Report	true
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	MIRM
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2024 Annual Meeting of Stockholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year ended December 31, 2023, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California
Auditor Firm ID	42
Document Financial Statement Error Correction [Flag]	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 286,326,000	$ 28,003,000
Short-term investments	0	123,716,000
Accounts receivable	67,968,000	23,994,000
Inventory	22,312,000	5,565,000
Prepaid expenses and other current assets	10,935,000	8,947,000
Total current assets	387,541,000	190,225,000
Restricted cash equivalents	0	100,000,000
Property and equipment, net	706,000	914,000
Operating lease right-of-use assets	1,284,000	1,431,000
Intangible assets, net	252,925,000	58,954,000
Other assets	4,165,000	1,382,000
Total assets	646,621,000	352,906,000
Current liabilities:
Accounts payable	7,416,000	8,690,000
Accrued expenses	78,544,000	54,018,000
Operating lease liabilities	1,104,000	931,000
Derivative liability	0	1,090,000
Total current liabilities	87,064,000	64,729,000
Revenue interest liability, net	0	140,351,000
Operating lease liabilities, noncurrent	617,000	1,257,000
Convertible notes payable, net	306,421,000	0
Other liabilities	3,849,000	4,532,000
Total liabilities	397,951,000	210,869,000
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized, and 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; 46,723,143 and 36,956,345 shares issued and outstanding as of December 31, 2023 and 2022	5,000	4,000
Additional paid-in capital	803,260,000	535,074,000
Accumulated deficit	(556,239,000)	(392,824,000)
Accumulated other comprehensive income (loss)	1,644,000	(217,000)
Total stockholders’ equity	248,670,000	142,037,000
Total liabilities and stockholders’ equity	$ 646,621,000	$ 352,906,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares, issued	0	0
Preferred stock, shares, outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	46,723,143	36,956,345
Common stock, shares, outstanding	46,723,143	36,956,345

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues [Abstract]
Total revenue	$ 186,374	$ 77,062	$ 19,138
Operating expenses:
Cost of sales	47,039	12,374	1,903
Research and development	102,609	106,842	131,428
Selling, general and administrative	145,880	89,066	59,220
Total operating expenses	295,528	208,282	192,551
Loss from operations	(109,154)	(131,220)	(173,413)
Other income (expense):
Interest income	13,735	3,857	366
Interest expense	(15,105)	(15,979)	(17,590)
Change in fair value of derivative liability	0	906	(732)
Loss from termination of revenue interest purchase agreement	(49,076)	0	0
Gain from sale of priority review voucher, net	0	0	108,000
Other (expense) income, net	(2,824)	365	(582)
Net loss before provision for income taxes	(162,424)	(142,071)	(83,951)
Provision for (benefit from) income taxes	991	(6,406)	37
Net loss	$ (163,415)	$ (135,665)	$ (83,988)
Net loss per share:
Basic	$ (4)	$ (4.01)	$ (2.77)
Diluted	$ (4)	$ (4.02)	$ (2.77)
Weighted-average shares outstanding:
Basic	40,885,124	33,839,072	30,321,722
Diluted	40,885,124	33,982,493	30,321,722
Product
Revenues [Abstract]
Total revenue	$ 178,874	$ 75,062	$ 3,138
License
Revenues [Abstract]
Total revenue	$ 7,500	$ 2,000	$ 16,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (163,415)	$ (135,665)	$ (83,988)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale investments	230	(194)	(117)
Cumulative translation adjustments	1,631	12	(1)
Comprehensive loss	$ (161,554)	$ (135,847)	$ (84,106)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Equity Incentive Plan	Employee Stock Purchase Plan (ESPP)	At-the-market Offering	Public Offering	Private Placement	Common Stock	Common Stock Equity Incentive Plan	Common Stock Employee Stock Purchase Plan (ESPP)	Common Stock At-the-market Offering	Common Stock Public Offering	Common Stock Private Placement	Additional Paid-In Capital	Additional Paid-In Capital Equity Incentive Plan	Additional Paid-In Capital Employee Stock Purchase Plan (ESPP)	Additional Paid-In Capital At-the-market Offering	Additional Paid-In Capital Public Offering	Additional Paid-In Capital Private Placement	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2020	$ 172,095						$ 3						$ 345,180						$ (173,171)	$ 83
Balance, Shares at Dec. 31, 2020							29,776,544
Issuance of common stock					$ 7,038												$ 7,038
Issuance of common stock, Shares											375,654
Issuance of common stock in connection with Employee Stock Purchase Plan		$ 844	$ 1,254											$ 844	$ 1,254
Issuance of common stock in connection with Employee Stock Purchase Plan, Shares								207,595	89,211
Restricted common stock vested in the period, Shares							133,592
Stock-based compensation	23,087												23,087
Net Income (Loss)	(83,988)																		(83,988)
Other comprehensive income loss	(118)																			(118)
Balance at Dec. 31, 2021	120,212						$ 3						377,403						(257,159)	(35)
Balance, Shares at Dec. 31, 2021							30,582,596
Issuance of common stock				$ 21,289	$ 86,078						$ 1					$ 21,289	$ 86,077
Issuance of common stock, Shares										1,160,915	4,000,000
Issuance of common stock in connection with asset acquisition, shares							609,305
Issuance of common stock in connection with asset acquisition	15,585												15,585
Issuance of common stock in connection with Employee Stock Purchase Plan		5,438	1,834											5,438	1,834
Issuance of common stock in connection with Employee Stock Purchase Plan, Shares								357,934	123,131
Restricted common stock vested in the period, Shares							122,464
Stock-based compensation	27,448												27,448
Net Income (Loss)	(135,665)																		(135,665)
Other comprehensive income loss	(182)																			(182)
Balance at Dec. 31, 2022	142,037						$ 4						535,074						(392,824)	(217)
Balance, Shares at Dec. 31, 2022							36,956,345
Issuance of common stock				$ 14,480		$ 202,204						$ 1				$ 14,480		$ 202,203
Issuance of common stock, Shares										658,206		8,000,000
Issuance of common stock in connection with asset acquisition, shares							231,624
Issuance of common stock in connection with asset acquisition	5,188												5,188
Issuance of common stock in connection with Employee Stock Purchase Plan		$ 8,279	$ 2,191											$ 8,279	$ 2,191
Issuance of common stock in connection with Employee Stock Purchase Plan, Shares								760,226	116,742
Stock-based compensation	35,845												35,845
Net Income (Loss)	(163,415)																		(163,415)
Other comprehensive income loss	1,861																			1,861
Balance at Dec. 31, 2023	$ 248,670						$ 5						$ 803,260						$ (556,239)	$ 1,644
Balance, Shares at Dec. 31, 2023							46,723,143

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - Common Stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
At-the-market Offering
Issuance Costs	$ 518	$ 785
Private Placement
Issuance Costs	$ 7,796
Public Offering
Issuance Costs		$ 5,922	$ 476

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (163,415)	$ (135,665)	$ (83,988)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation	35,023	27,007	23,087
Depreciation and amortization	10,829	3,238	595
Non-cash lease expense	620	443	380
Net accretion of discounts on investments	(1,725)	(1,703)	(137)
Non-cash interest expense related to the revenue interest liability	5,060	15,979	17,590
Amortization of debt discount and offering costs	1,117	0	0
Change in fair value of derivative liability	0	(906)	732
Change in fair value of contingent liabilities associated with acquisition	671	(899)	0
Inventory reserves and firm purchase commitment losses	9,257	0	0
Loss from termination of revenue interest purchase agreement	49,076	0	0
Costs recognized on sale of acquired inventory	3,419	0	0
Unrealized foreign exchange loss	1,764	0	0
Deferred income taxes associated with an acquisition	0	(6,580)	0
Gain on sale of priority review voucher, net	0	0	(108,000)
Change in operating assets and liabilities:
Accounts receivable	(43,974)	(20,727)	0
Prepaid and other current assets	(3,600)	(3,676)	(4,009)
Inventory	(4,393)	(3,448)	(495)
Other assets	(511)	(127)	(519)
Accounts payable, accrued expenses and other liabilities	30,778	7,639	22,655
Operating lease liabilities	(940)	(711)	(649)
Net cash used in operating activities	(70,944)	(120,136)	(132,758)
Investing activities
Purchase of investments	(27,329)	(132,322)	(198,029)
Proceeds from maturities of investments	153,000	140,300	155,600
Proceeds from paydown of investments	0	0	2,000
Purchase of property and equipment	(109)	(278)	(24)
Cash paid for acquisition	(212,762)	0	0
Payments made for additions to intangible assets	(20,000)	0	(19,000)
Proceeds from sale of priority review voucher, net	0	0	108,000
Net cash (used in) provided by investing activities	(107,200)	7,700	48,547
Financing activities
Proceeds from issuance of common stock in private placement, net of issuance costs	202,204	0	0
Proceeds from issuance of common stock in at-the-market offerings, net of issuance costs	14,480	21,289	0
Proceeds from issuance of common stock in public offerings, net of issuance costs	0	86,078	6,914
Proceeds from the issuance of convertible notes, net	305,304	0	0
Proceeds from issuance of common stock pursuant to equity plans	10,470	7,272	2,098
Payments of deferred offering costs	(281)	0	0
Payments on revenue interest liability	(195,577)	(5,552)	(121)
Proceeds from revenue interest liability, net of issuance costs	0	0	64,575
Net cash provided by financing activities	336,600	109,087	73,466
Effect of exchange rate on cash, cash equivalents and restricted cash equivalents	(133)	12	(1)
Net increase (decrease) in cash, cash equivalents and restricted cash equivalents	158,323	(3,337)	(10,746)
Cash, cash equivalents and restricted cash equivalents at beginning of period	128,003	131,340	142,086
Cash, cash equivalents and restricted cash equivalents at end of period	286,326	128,003	131,340
Supplemental disclosure of cash flow information:
Operating cash flows paid for operating lease	1,079	911	864
Cash paid for income taxes	125	0	0
Cash paid for interest	6,817	0	0
Noncash investing and financing activities:
Inventory purchases included in accrued liabilities	6,076	163	1,018
Right-of-use asset obtained in exchange for lease liability	473	285	0
Stock-based compensation capitalized into inventory	822	441	71
Issuance of common stock in connection with settlement of Contingent Milestone and Indemnification Holdback liabilities	5,188	0	0
Issuance of common stock in exchange for acquired intangible assets	0	15,585	0
Accrued milestone payments classified as intangible assets, net	0	15,000	0
Deferred Tax Liability Incurred From Acquired Intangible	0	6,580	0
Contingent milestone liability for common stock issuance for acquired intangible assets	0	4,600	0
Indemnification Holdback liability for common stock issuance in exchange for acquired intangible assets	$ 0	$ 831	$ 0

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (163,415)	$ (135,665)	$ (83,988)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During our last fiscal quarter, our directors and officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted or terminated the contracts, instructions or written plans for the purchase or sale of the Company’s securities set forth in the table below. Type of Trading Arrangement Name and Position Action Adoption/ Termination Date Rule 10b5-1* Non- Rule 10b5-1** Total Shares of Common Stock to be Sold Expiration Date Christopher Peetz , Chief Executive Officer Adopted December 28, 2023 X Up to 75,000 December 28, 2025 * Contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. ** “ No n-Rule 10b5-1 trading arrangement” as defined in Item 408(c) of Regulation S-K under the Exchange Act.
Name	Christopher Peetz
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Adoption Date	December 28, 2023
Aggregate Available	75,000
Expiration Date	December 28, 2025

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Mirum Pharmaceuticals, Inc. (the “Company”) was incorporated in the State of Delaware on May 2, 2018 , and is headquartered in Foster City, California. The Company is a biopharmaceutical company focused on the identification, acquisition, development and commercialization of novel therapies for debilitating rare and orphan diseases. The Company has three approved medicines: LIVMARLI® (maralixibat) oral solution (“Livmarli”), Cholbam® (cholic acid) capsules, and Chenodal® (chenodiol) tablets (“Chenodal”). Livmarli is approved for the treatment of cholestatic pruritus in patients with Alagille syndrome (“ALGS”) three months of age and older and cholestatic pruritus in patients with primary familial intrahepatic cholestasis (“PFIC”) five years of age and older in the United States, and for the treatment of cholestatic pruritus in patients with ALGS two months of age and older in Europe. On July 16, 2023, the Company entered into an Asset Purchase Agreement (the “Purchase Agreement”) with Travere Therapeutics, Inc., a Delaware corporation (“Travere”), pursuant to which, upon the closing in August 2023, the Company acquired Travere’s bile acid product portfolio, including Chenodal and Cholbam (also known as Kolbam, and together with Chenodal, the “Bile Acid Medicines”), two therapies addressing rare diseases in high-need settings (such acquisition, the “Bile Acid Portfolio Acquisition”) (Note 7). Cholbam is FDA-approved for the treatment of bile acid synthesis disorders due to single enzyme deficiencies and adjunctive treatment of peroxisomal disorders in patients who show signs or symptoms or liver disease. Chenodal is approved for the treatment of radiolucent stones in the gallbladder and has received medical necessity recognition by the FDA for the treatment of cerebrotendinous xanthomatosis (“CTX”). The Company’s development pipeline consists of the clinical-stage product candidate volixibat and life-cycle extension opportunities for Livmarli. The Company commenced significant operations in November 2018. The Company views its operations and manages its business as one operating segment. The Company determined its operating segment on the same basis that it uses to evaluate its performance internally. Liquidity The Company has a limited operating history, has incurred significant operating losses since its inception, and the revenue and income potential of the Company’s business and market are unproven. As of December 31, 2023, the Company had an accumulated deficit of $ 556.2 million and cash and cash equivalents of $ 286.3 million. The Company believes that its cash and cash equivalents of $ 286.3 million as of December 31, 2023 provide sufficient capital resources to continue its operations for at least twelve months from the issuance date of the accompanying consolidated financial statements. The consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development activities. In April 2023, the Company completed a convertible notes offering, as further described in Note 10, with net proceeds of $ 305.3 million, after deducting the initial purchasers’ discounts and commissions and offering expenses. From the net proceeds, $ 192.7 million was used to repurchase all future revenue interests (the “Revenue Interests”) in connection with the Company’s Revenue Interest Purchase Agreement (“RIPA”) (Note 6). Upon repurchase and the termination of the RIPA, in accordance with its terms, the previously restricted cash equivalents of $ 100.0 million were no longer restricted from use. In August 2023, the Company completed the Bile Acid Portfolio Acquisition contemplated by the Purchase Agreement and acquired substantially all of the assets of Travere that are primarily related to the development, manufacture and commercialization of the Bile Acid Medicines. Under the terms of the Purchase Agreement, the Company paid an upfront purchase price of $ 210.4 million in cash to Travere and may pay additional amounts of up to $ 235.0 million upon the achievement of certain milestones based on specified amounts of net annual sales of the Bile Acid Medicines. In connection with and immediately prior to the closing of the Bile Acid Portfolio Acquisition, the Company completed the private placement of 8,000,000 shares of the Company's common stock at a price per share of $ 26.25 , resulting in net proceeds of approximately $ 202.2 million.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. The Company translates the financial statements of its foreign subsidiaries using end-of-period exchange rates for assets and liabilities and average exchange rates during each reporting period for results of operations. All intercompany balances and transactions among the consolidated entities have been eliminated in consolidation. The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in the financial statements and accompanying notes. These estimates and assumptions are based upon historical experience, knowledge of current events and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources. Actual results could differ materially from those estimates. The Company’s consolidated financial statements as of and for the year ended December 31, 2023 reflect the Company’s estimates of the impact of the geopolitical and macroeconomic environment, including the impact of inflation, bank failures, high interest rates and foreign exchange rate fluctuations. The duration and the scope of these conditions cannot be predicted; therefore, the extent to which these conditions will directly or indirectly impact the Company’s business, results of operations and financial condition, is uncertain. The Company is not aware of any specific event or circumstance that would require an update to its estimates, judgments and assumptions or a revision of the carrying value of the Company’s assets or liabilities as of the date of this filing. Cash, Cash Equivalents and Restricted Cash Equivalents The Company considers all highly liquid investments that are readily convertible into cash without penalty and with original maturities of three months or less at the date of purchase to be cash equivalents. The carrying amounts reported in the consolidated balance sheets for cash and cash equivalents are valued at cost, which approximate their fair value. Restricted cash equivalents as of December 31, 2022 consisted of deposits placed in a segregated bank account as required under the terms of the Company’s RIPA, as amended in September 2021, with Mulholland SA LLC, an affiliate of Oberland Capital LLC (“Oberland”), as agent for the purchasers party thereto (the “Purchasers”), and the Purchasers in connection with the sale of the Priority Review Voucher in December 2021. Upon repurchase and the termination of the RIPA in April 2023, in accordance with its terms, the previously restricted cash equivalents of $ 100.0 million were no longer restricted from use. The following table provides a reconciliation of cash, cash equivalents and restricted cash equivalents reported within the consolidated balance sheets that together reflect the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 286,326 $ 28,003 Restricted cash equivalents — 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 286,326 $ 128,003 Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, accounts receivable and investments. The Company limits the amount of credit exposure by investing cash that is not required for immediate operating needs in money market funds, government obligations and/or commercial paper with short maturities. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities, which are designed to maintain principal and maximize liquidity. To date, the Company has not experienced any losses associated with this credit risk and continues to believe that this exposure is not significant. The Company relies on a specialty pharmacy and a single distributor for all of the Company’s sales of Livmarli in the United States as well as a single distributor for sales outside the United States. The Company relies on a specialty pharmacy for all the Company’s sales of Chenodal and Cholbam in the United States. The Company sources materials and services through several vendors. Certain materials are sourced from a single vendor. The loss of certain vendors could result in a temporary disruption of the Company’s commercialization efforts. As of December 31, 2023 , the Company did no t have any customers that individually accounted for more than 10 % of accounts receivable. As of December 31, 2022 , the Company had one customer that accounted for approximately 23 % of accounts receivable. For the years ended December 31, 2023, 2022 and 2021 , the Company did not have revenue attributable to any one customer in excess of 10 % of sales. Investments The Company classifies all investments in securities as available-for-sale. Management determines the appropriate classification of its investments in securities at the time of purchase. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than twelve months from the balance sheet date, are classified as a current asset. Investments are recorded at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized, with the exception of any declines in fair value below the cost basis that are a result of a credit loss, which, if any, are reported in other income (expense), net in the current period through an allowance for credit losses. Each reporting period, the Company evaluates whether declines in fair values of its available-for-sale securities below their cost basis are a result of credit loss or other factors and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss, the creditworthiness of the security issuers, as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis and are also included in other income (expense). To date, the Company has no t identified any declines in fair value of its investments related to credit loss. Fair Value of Financial Instruments Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement determined based on assumptions that market participants would use in pricing an asset or liability. The following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: Level 1: Observable inputs (unadjusted) such as quoted prices in active markets for identical assets or liabilities; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly for similar assets or liabilities; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Accounts Receivable The Company has accounts receivable amounts due from product sales. The Company also has accounts receivable amounts due from license agreements for milestones achieved, but not yet paid. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company estimates the allowance for credit losses using the current expected credit loss model. Under this model, the allowance for credit losses reflects the Company’s estimate of lifetime expected credit losses. The Company evaluates the collectability of the cash flows based on the risk of loss over the contractual life, even when that risk is remote, based on judgments about the creditworthiness of its customers, historical experience and other relevant information that is available to the Company. There was no allowance for credit losses as of December 31, 2023 . There was no bad debt expense for the years ended December 31, 2023, 2022 and 2021 . Inventory Inventory is valued at the lower of cost or net realizable value, with cost determined on a first-in, first-out (FIFO) basis. The Company periodically reviews the composition of inventory to identify excess, obsolete, slow-moving or otherwise unsaleable items. If unsaleable items are observed and there are no alternate uses for the inventory, the Company will record a write-down to net realizable value in the period that the decline in value is recognized through a charge to cost of sales. Furthermore, the Company periodically reviews its firm commitments for the purchase of minimum order quantities. If the minimum order quantities exceed the Company’s future demand, a net loss is accrued in cost of sales for such future inventory purchases. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required. Accruals for firm purchase commitments amounted to $ 5.2 million as of December 31, 2023, of which $ 3.8 million was included in other liabilities on the consolidated balance sheets. Prior to the initial regulatory approval for Livmarli, the Company expensed costs relating to raw materials and production of inventory as research and development expense in the accompanying consolidated statements of operations, in the period incurred. The Company has substantially depleted such inventories as of December 31, 2023. Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, ranging from three to five years . Leasehold improvements are amortized over the shorter of their useful lives or the related lease term. As of December 31, 2023 , property and equipment consisted primarily of leasehold improvements of $ 1.3 million and furniture and equipment of $ 0.9 million. As of December 31, 2022 , property and equipment consisted primarily of leasehold improvements of $ 1.3 million and furniture and equipment of $ 0.6 million. Accumulated depreciation as of December 31, 2023 and 2022 was $ 1.5 million and $ 1.0 million, respectively. Depreciation expense was $ 0.3 million for each of the years ended December 31, 2023, 2022 and 2021 . Impairment of Long-Lived Assets Long-lived assets are reviewed for indications of possible impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amounts to the future undiscounted cash flows attributable to these assets. An impairment loss is recognized to the extent an asset group is not recoverable, and the carrying amount exceeds the projected discounted future cash flows arising from these assets. There were no impairments of long-lived assets for any of the periods presented. Intangible Assets, Net The Company accounts for asset acquisitions that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the asset (or assets) acquired on the basis of its (or their) relative fair value(s) on the measurement date. No goodwill is recognized in an asset acquisition. Intangible assets are measured at their fair values as of the acquisition date or, in the case of commercial milestone payments, the date they become due. The evaluation of intangible assets includes assessing the amortization period for which the asset is expected to contribute to the future cash flows of the Company. Intangible assets with finite useful lives are amortized over their estimated useful lives, primarily on a straight-line basis when the Company is unable to reliably estimate the pattern of cash flow. The Company tests its finite lived intangible assets for impairment annually or if events or changes in circumstances indicate that it is more likely than not that the asset is impaired. If it is determined that the asset is impaired, the carrying value is written down to its estimated fair value, with the related impairment charge recognized in the consolidated statements of operations in the period in which the impairment occurs. The Company has not recorded any impairments to its intangible assets for any of the periods presented. The components of the Company’s intangible assets were as follows (in thousands, except for weighted-average remaining amortization period): December 31, 2023 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 39,000 $ ( 3,318 ) $ 35,682 16.2 Developed technology 226,620 ( 10,239 ) 216,381 11.7 Assembled workforce 970 ( 108 ) 862 2.7 Total intangible assets $ 266,590 $ ( 13,665 ) $ 252,925 12.3 December 31, 2022 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 34,000 $ ( 1,333 ) $ 32,667 17.1 Developed technology 28,107 ( 1,820 ) 26,287 8.4 Total intangible assets $ 62,107 $ ( 3,153 ) $ 58,954 11.9 Amortization expense was $ 10.5 million, $ 2.9 million and $ 0.3 million for the years ended December 31, 2023, 2022 and 2021, respectively, and was included in cost of sales on the accompanying consolidated statements of operations. The following table summarizes the estimated future amortization expense associated with the Company’s intangible assets as of December 31, 2023 (in thousands): Amount 2024 $ 21,545 2025 21,545 2026 21,436 2027 21,221 2028 21,221 Thereafter 145,957 $ 252,925 Leases The Company determines if a contractual arrangement is or contains a lease at inception. Operating lease right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset during the lease term, and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating leases are included in ROU assets, current operating lease liabilities, and long-term operating lease liabilities on the accompanying consolidated balance sheets. Operating lease ROU assets and lease liabilities are initially recognized based on the present value of the future minimum lease payments over the lease term at commencement date calculated using the Company’s incremental borrowing rate applicable to the leased asset, unless the implicit rate is readily determinable. Operating lease ROU assets also include any lease payments made at or before lease commencement and exclude any lease incentives received. The Company determines the lease term as the noncancelable period of the lease and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Leases with a term of 12 months or less are not recognized on the consolidated balance sheets. The Company’s leases do not contain any residual value guarantees. Lease expense for minimum lease payments is recognized as rent expense on a straight-line basis over the lease term. Variable lease payments include lease operating expenses. Accrued Research and Development Expenses The Company accrues and expenses clinical trial activities performed by third parties based upon estimates of the proportion of work completed over the life of the individual study and patient enrollment rates in accordance with agreements established with clinical research organizations and clinical trial sites. The Company determines the estimates by reviewing contracts, vendor agreements and purchase orders and through discussions with internal clinical personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services. The Company makes estimates of accrued expenses as of each balance sheet date based on facts and circumstances known to the Company at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. The Company has not experienced any material differences between accrued costs and actual costs incurred for the periods presented. Nonrefundable advance payments for goods and services are deferred and recognized as expense in the period that the related goods are consumed or services are performed. Convertible Notes The Company evaluates all conversion, repurchase and redemption features contained in a debt instrument to determine if there are any embedded features that require bifurcation as a derivative. The Company accounts for its convertible notes (refer to Note 10) as a long-term liability equal to the proceeds received from issuance, including any embedded conversion features, net of the unamortized debt discount and offering costs in the accompanying consolidated balance sheets. The debt issuance and offering costs are amortized over the contractual term of the convertible notes, using the effective interest method, as interest expense in the accompanying consolidated statements of operations. Revenue Interest Liability, Net The revenue interest liability, net, associated with the RIPA that the Company entered into in December 2020, as amended in September 2021, with Oberland as agent for Purchasers, and the Purchasers, was presented net of issuance costs and a debt discount on the consolidated balance sheet as of December 31, 2022. The Company imputed interest expense associated with this liability using the effective interest rate method. The effective interest rate was calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on the liability varied during the term of the agreement depending on a number of factors, including the level of actual and forecasted product sales, net. The Company evaluated the interest rate quarterly based on actual product sales, net and forecast product sales, net, utilizing the prospective method. In April 2023, the Company repurchased all future Revenue Interests and as a result, the RIPA was terminated in accordance with its terms (refer to Note 6). Derivative Liability The RIPA contained certain features that met the definition of being an embedded derivative requiring bifurcation as a separate compound financial instrument apart from the RIPA. The derivative liability was initially measured at fair value on issuance and was subject to remeasurement at each reporting period with changes in fair value recognized as other income (expense) in the accompanying consolidated statements of operations as the change in fair value of derivative liability. In April 2023, the derivative liability was extinguished in connection with the termination of the RIPA (refer to Note 6). Revenue Recognition The Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for those goods or services. Product Sales, Net The Company recognizes product sales, net when the customer obtains control of our product, which occurs at a point in time, typically upon delivery of the Company’s product to the customer. Revenues from product sales are recorded at the net sales price, or the transaction price, which may include fixed or variable consideration for discounts, government rebates, co-pay assistance, returns and other allowances that are offered within contracts with a customer relating to the sale of the Company's approved medicines. Estimates of variable consideration are calculated based on the actual product sales each reporting period and the nature of the variable consideration related to those sales. Overall, these estimates reflect the Company’s best estimate of the amount of consideration to which the Company expects to be entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in product sales, net only to the extent that it is considered probable that a significant reversal in the amount of the cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Estimates are reviewed and updated quarterly as additional information becomes known. Actual amounts of consideration ultimately received may differ materially from estimates. If actual results in the future vary from estimates, the Company will adjust these estimates, which would affect product sales, net and earnings in the period such variances are adjusted. Significant categories of sales discounts and allowances are as follows: Government Rebates : The Company records rebates payable under Medicaid and other government programs as a reduction of revenue at the time product revenues are generated. The Company’s rebate calculations may require estimates, including estimates of customer mix, to determine which sales will be subject to rebates and the amount of such rebates. The Company updates its estimates and assumptions on a quarterly basis and records any necessary adjustments to revenue in the period identified. The liability for unpaid rebates is included in accrued expenses on the accompanying consolidated balance sheets. To date, actual government rebates have not differed materially from the Company’s estimates. Other Incentives: Other incentives include a branded co-pay assistance program for eligible patients with commercial insurance in the United States. The branded co-pay assistance program assists commercially insured patients who have coverage for the Company's approved medicines and is intended to reduce each participating patient’s portion of the financial responsibility of the purchase price up to a specified dollar amount of assistance. The calculation of the accrual for co-pay assistance is based upon an identification of claims and the cost per claims associated with product that has been recognized as revenue. The Company records amounts paid under the brand specific co-pay assistance program for each patient as a reduction of revenue from product sales. To date, actual other incentives have not differed materially from the Company’s estimates. Product Returns: The Company records revenue for product sales, net of estimated product returns. Customers have limited return rights related only to the product’s damage or defect identified upon delivery of the product. The Company estimates the amount of product sales that may be returned and records the estimate as a reduction of revenue and a refund liability in the period the related product revenue is recognized. To date, actual returns have not differed materially from the Company’s estimates. The following table presents Total revenues and disaggregates Product sales, net by approved medicine (in thousands): Year Ended December 31, 2023 2022 2021 Product sales, net: Livmarli $ 141,795 $ 75,062 $ 3,138 Bile Acid Medicines 37,079 — — Total product sales, net 178,874 75,062 3,138 License revenue 7,500 2,000 16,000 Total revenues $ 186,374 $ 77,062 $ 19,138 The following table sets forth Product sales, net by geographic area based on the ship-to location (in thousands): Year Ended December 31, 2023 2022 2021 United States $ 146,699 $ 67,920 $ 2,913 Rest of world 32,175 7,142 225 Total product sales, net $ 178,874 $ 75,062 $ 3,138 License and Collaboration Arrangements The Company enters into collaborative arrangements with partners and analyzes the collaboration arrangements to assess whether they are within the scope of Collaborative Arrangements (Topic 808) ("Topic 808") and determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be subject to Revenue from Contracts with Customers (Topic 606) (“Topic 606”) for distinct units of account that are reflective of a vendor-customer relationship. For other elements of collaboration arrangements, such as reimbursements of certain development costs, the Company generally records reimbursements received as a reduction of research and development expenses. In determining the appropriate amount of revenue to be recognized under Topic 606 as the Company fulfills its obligations under each of its agreements, the Company performs the following steps: (i) identification of the contracts with customers; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) determination and measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations in the contract; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The terms of the Company’s license and collaborative research and development agreements include upfront license fees, research, development and other funding or reimbursements, milestone and other contingent payments for the achievement of defined collaboration objectives and certain development, regulatory and sales-based events, as well as royalties on sales of commercialized products. Arrangements that include upfront payments may require deferral of revenue recognition to a future period until the Company satisfies performance obligations under these arrangements. A performance obligation is a promise in a contract to transfer a distinct good or service and is the unit of accounting in Topic 606. A contract’s transaction price is allocated among each distinct performance obligation based on relative standalone selling price and recognized as revenue when, or as, the applicable performance obligation is satisfied. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price as variable consideration using the most likely amount method or expected value method, depending on the nature of the contingency and the variable payments. If it is probable that a significant reversal of cumulative revenue recognized for the contract would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not generally considered probable of being achieved until those approvals are received. Given the high degree of uncertainty around the occurrence of these events, the Company generally determines the milestone and other contingent amounts to be fully constrained until the uncertainty associated with these payments is resolved. At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, the Company recognizes revenue at the later of (i) when or as the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Accounting for these arrangements requires the Company to develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. The Company has never sold the performance obligations in its collaborative arrangements separately; therefore, an observable stand-alone selling price does not exist. Accordingly, the Company estimates a stand-alone selling price through maximizing the use of observable inputs such as market data, project cost estimates, and targeted margins. Cost of Product Sales Prior to receiving approval from the U.S. Food and Drug Administration ("FDA") or other foreign regulatory authorities for a new medicine or new formulation, the Company expenses all costs incurred related to the manufacture of such medicines as research and development expense because of the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company of regulatory approval of drug candidates. Subsequent to receiving FDA or other foreign regulatory authority approval, when commercialization is considered probable and the future economic benefit is expected to be realized, the Company begins capitalizing inventory costs incurred. Cost of product sales consist of manufacturing costs, transportation and freight, amortization of capitalized intangible assets, royalties and indirect overhead costs associated with the manufacturing and distribution of the Company's approved products. Cost of product sales may also include period costs related to certain manufacturing services and inventory adjustment charges. Research and Development Expenses Research and development expenses consists primarily of fees paid to contract research organizations and other vendors for clinical, non-clinical and manufacturing services, salaries and employee benefits, including stock-based compensation, consultant expenses, costs related to acquiring manufacturing materials, costs related to compliance with regulatory requirements and license payments related to acquiring intellectual property rights for the Company’s product candidates. Research and development expenses are expensed as incurred. Selling, General and Administrative Expenses Selling, general and administrative (“SG&A”) expenses relate to sales and marketing, finance, human resources, legal and other administrative activities. SG&A expenses consist primarily of personnel costs, facilities and overhead costs, outside marketing, advertising and legal expenses, and other general and administrative costs. The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $ 6.3 million, $ 4.0 million and $ 9.2 million for the years ended December 31, 2023, 2022 and 2021 , respectively. Stock-Based Compensation The Company recognizes stock-based compensation for all stock-based awards based on the grant date fai

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type are presented in the following table (in thousands): December 31, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 278,116 $ — $ — $ 278,116 Total financial assets $ 278,116 $ — $ — $ 278,116 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 124,227 $ — $ — $ 124,227 U.S. treasury bills 4,975 — — 4,975 Commercial paper — 74,386 — 74,386 U.S. government bonds — 44,354 — 44,354 Total financial assets $ 129,202 $ 118,740 $ — $ 247,942 Financial liabilities: Contingent milestone liability $ 3,900 $ — $ — $ 3,900 Derivative liability — — 1,090 1,090 Indemnification holdback — — 617 617 Total financial liabilities $ 3,900 $ — $ 1,707 $ 5,607 The carrying amounts of certain financial instruments such as cash and cash equivalents, restricted cash equivalents, accounts receivable, prepaid expenses, other current assets, accounts payable and accrued expenses as of December 31, 2023 and 2022 approximate their related fair values due to the short-term maturities of these instruments. Money market funds and U.S. treasury bills are highly liquid investments and are actively traded. The pricing information on these investment instruments is readily available and can be independently validated as of the measurement date. This approach results in the classification of these securities as Level 1 of the fair value hierarchy. U.S. government bonds and commercial paper are measured at fair value using Level 2 inputs. The Company reviews trading activity and pricing for these investments as of each measurement date. The carrying amount of the revenue interest liability as of December 31, 2022 approximates its fair value and is based on the Company’s contractual repayment obligation to the Purchasers, based on the current estimates of future revenues, over the life of the RIPA. At the time of issuance, the Contingent Milestone liability was recognized at fair value using Level 3 inputs as no observable inputs were available at the time in the market. As of December 31, 2022, the Contingent Milestone liability is considered a Level 1 input as the significant inputs were known and observable. The derivative liability and Indemnification Holdback liability (each as defined below) as of December 31, 2022 are each considered a Level 3 input based on the three-level hierarchy. Derivative Liability The debt pursuant to the RIPA (refer to Note 6 “Revenue Interest Purchase Agreement” for further information) contained an embedded derivative requiring bifurcation as a single compound derivative instrument. The Company estimated the fair value of the derivative liability using a “with-and-without” method. The “with-and-without” methodology involves valuing the whole instrument on an as-is basis and then valuing the instrument without the individual embedded derivative. The difference between the entire instrument with the embedded derivative compared to the instrument without the embedded derivative was the fair value of the derivative liability at December 31, 2022. The estimated probability and timing of underlying events triggering the exercisability of the put option contained within the RIPA, forecasted cash flows and the discount rate were significant unobservable inputs used to determine the estimated fair value of the entire instrument with the embedded derivative. As of December 31, 2022, the discount rate used for valuation of the derivative liability was 15.7 %. In 2023, there was no change in the fair value of the derivative liability prior to its extinguishment in connection with the termination of the RIPA in April 2023. Indemnification Holdback and Contingent Milestone Liabilities In May 2022, in connection with the acquisition of Satiogen (refer to Note 7 “Asset Acquisitions” for further information), the Company recorded at fair value liabilities related to the Company’s common stock issuable upon satisfaction of certain purchase price adjustments and indemnification obligations that may arise during the 12 month period following the asset acquisition date (“Indemnification Holdback”) and contingent consideration upon achievement of a certain milestone (“Contingent Milestone”). The fair value of the Indemnification Holdback and the Contingent Milestone was classified within Level 3 of the fair value hierarchy and was estimated based upon the value of the Company’s common stock price. The fair value of the Indemnification Holdback was additionally determined based on management’s estimate of the probability of indemnification obligations being incurred during the one year following the acquisition date, while the fair value of the Contingent Milestone was additionally determined based upon management’s estimate of the probability of the milestone being met. The fair value of the Indemnification Holdback and Contingent Milestone was initially measured on May 20, 2022, the date on which the Company completed the acquisition of Satiogen. The Company assessed the fair value of the Indemnification Holdback and Contingent Milestone each reporting period until resolution of the related contingency, and changes in fair value were recorded in other income (expense), net in the accompanying consolidated statements of operations. As of December 31, 2022, the contingency for the Contingent Milestone was resolved and the fair value of t he liability was determined based solely upon the closing price of the Company’s common stock. In January 2023, the Company issued 199,993 shares of common stock in connection with the Contingent Milestone liability. In June 2023, the contingencies related to the Indemnification Holdback were resolved and the Company issued 31,631 shares of common stock. The following table provides a summary of the changes in the estimated fair value of the Indemnification Holdback and Contingent Milestone liability within Level 3 of the fair value hierarchy (in thousands): Indemnification Holdback Liability Contingent Milestone Liability Balance at January 1, 2022 $ — $ — Initial recognition 831 4,600 Change in fair value ( 214 ) ( 700 ) Transfer out of Level 3 fair value hierarchy — ( 3,900 ) Balance at December 31, 2022 617 — Change in fair value 279 — Settlement of Indemnification Holdback liability ( 896 ) — Balance at December 31, 2023 $ — $ — The Contingent Milestone and Indemnification Holdback liability is included in other liabilities on the accompanying consolidated balance sheets as of December 31, 2022. There was no outstanding balance related to the Contingent Milestone and Indemnification Holdback liability as of December 31, 2023.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2023
Financial Instruments, Owned, at Fair Value, by Type, Alternative [Abstract]
Financial Instruments	4. Financial Instruments The fair value and amortized cost of cash equivalents and available-for-sale investments by major security type are presented in the following table (in thousands): December 31, 2023 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 278,116 $ — $ — $ 278,116 Total cash equivalents and investments $ 278,116 $ — $ — $ 278,116 Classified as: Cash equivalents $ 278,116 Total cash equivalents and investments $ 278,116 December 31, 2022 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market funds $ 124,227 $ — $ — $ 124,227 U.S. treasury bills 4,980 — ( 5 ) 4,975 Commercial paper 74,386 — — 74,386 U.S. government bonds 44,579 — ( 225 ) 44,354 Total cash equivalents and investments $ 248,172 $ — $ ( 230 ) $ 247,942 Classified as: Cash equivalents $ 24,226 Cash equivalents - restricted 100,000 Short-term investments 123,716 Total cash equivalents, restricted cash equivalents and investments $ 247,942 During the years ended December 31, 2023 and 2022, there have been no significant realized gains or losses on available-for-sale investments, no investments have been in a continuous unrealized loss position for more than 12 months, and the Company did no t recognize any credit losses on these securities.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2023
Balance Sheet Components [Abstract]
Balance Sheet Components	5. Balance Sheet Components Inventory Inventory consists of the following (in thousands): December 31, 2023 2022 Raw materials $ 2,998 $ — Work in progress 9,873 5,351 Finished goods 9,441 214 Total inventory $ 22,312 $ 5,565 Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, 2023 2022 Accrued compensation and related benefits $ 20,939 $ 14,660 Accrued sales deductions 23,650 4,284 Accrued clinical trials 7,268 8,319 Accrued professional service fees 7,941 5,372 Accrued manufacturing and non-clinical costs 9,922 3,927 Accrued royalties payable 6,716 2,456 Accrued interest 2,108 — Accrued milestone payments — 15,000 Total accrued expenses $ 78,544 $ 54,018

Revenue Interest Purchase Agree

Revenue Interest Purchase Agreement	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue Interest Purchase Agreement	6. Revenue Interest Purchase Agreement I n December 2020, the Company entered into the RIPA, as amended in September 2021, with Oberland as agent for the Purchasers, and the Purchasers to obtain financing for the commercialization and further development of Livmarli and other working capital needs. Pursuant to the RIPA, the Company has received $ 115.0 million consisting of an upfront payment of $ 50.0 million in December 2020 and $ 65.0 million in April 2021 associated with the acceptance for filing by the FDA of a New Drug Application for Livmarli for the treatment of cholestatic pruritus in patients with ALGS, less certain transaction expenses . Under the RIPA, the Company was entitled to receive an additional $ 35.0 million upon FDA approval of Livmarli, which it elected to forgo. The Company was also entitled to receive up to approximately $ 50.0 million at the option of the Purchasers to finance in-licenses or other acquisitions on or prior to December 31, 2022, which the Company did not request. As consideration for such payments, the Purchasers had the right to receive the Revenue Interests from the Company based on annual product sales, net of Livmarli, in tiered payments (the “Revenue Interest Payments”) based on whether annual product sales, net were (i) less than or equal to $ 350.0 million (“Tier 1”), (ii) exceeding $ 350.0 million and less than or equal to $ 1.1 billion (“Tier 2”), or (iii) exceeding $ 1.1 billion (“Tier 3”). The Revenue Interest Payments were initially 9.75 % (at Tier 1) and 2.0 % (at Tier 2 and Tier 3) of such annual net sales. Under the RIPA, the Company had an option (the “Call Option”) to terminate the RIPA and repurchase future Revenue Interests at any time upon advance written notice. Additionally, the Purchasers had an option (the “Put Option”) to terminate the RIPA and to require the Company to repurchase future Revenue Interests upon enumerated events such as a bankruptcy event, an uncured material breach, a material adverse effect or a change of control, or upon the 12 th anniversary of the first payment made by Purchasers. If the Put Option is exercised prior to the first anniversary of the closing date by the Purchasers (except pursuant to a change of control), the required repurchase price is 120.0 % of the Cumulative Purchaser Payments (minus all payments Company has made to the Purchasers in connection with the Revenue Interests). In all other cases, if the Put Option or the Call Option are exercised, the required repurchase price is 175.0 % of the Cumulative Purchaser Payments (minus all payments the Company has made to the Purchasers in connection with the Revenue Interests), if such option is exercised prior to the third anniversary of the closing date, and 195.0 % of the Cumulative Purchaser Payments (minus all payments Company has made to the Purchasers in connection with the Revenue Interests) if such option is exercised thereafter. In addition, the RIPA contained various representations and warranties, information rights, non-financial and financial covenants, indemnification obligations and other provisions that are customary for a transaction of this nature. The Purchasers’ obligations to fund the scheduled installments were subject to certain customary conditions as set forth in the RIPA. Concurrently with the RIPA, the Company entered into a Common Stock Purchase Agreement (“CSPA”) with certain affiliates of Oberland, pursuant to which the Company sold an aggregate of 509,164 shares of its common stock for an aggregate purchase price of $ 10.0 million. The $ 50.0 million upfront payment received pursuant to the RIPA and $ 10.0 million received pursuant to the CSPA was allocated between the resulting financial instruments on a relative fair value basis, with $ 49.2 million allocated to the debt under the RIPA and $ 10.8 million allocated to the common stock issued under the CSPA. The Put Option under the RIPA that was exercisable by Purchasers upon certain contingent events was determined to be an embedded derivative requiring bifurcation and separately accounted for as a single compound derivative instrument. The Company recorded the initial fair value of the derivative liability of $ 1.3 million as a debt discount, which was amortized to interest expense over the expected term of the debt using the effective interest method. The Company imputed interest expense associated with the revenue interest liability using the effective interest rate method. The effective interest rate was calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on this liability was variable during the term of the agreement depending on a number of factors, including the level of forecasted product sales, net. The Company evaluated the interest rate quarterly based on each period's product sales, net forecasts utilizing the prospective method. The Company recorded interest expense related to this arrangement of $ 5.1 million, $ 16.0 million and $ 17.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company incurred $ 0.9 million of issuance costs in connection with the RIPA, which were being amortized to interest expense over the estimated term of the debt. In April 2023, the Company exercised the Call Option and repurchased all future Revenue Interests. In connection with such repurchase, the Company made a payment of $ 192.7 million, or 175 % of the Cumulative Purchaser Payments (minus all payments that were made to the Purchasers in connection with the Revenue Interests). As a result, the RIPA terminated in accordance with its terms. The following table summarizes the revenue interest liability activity during the years ended December 31, 2023 and 2022 (in thousands): Revenue Interest Liability Derivative Liability Balance at January 1, 2022 $ 129,923 $ 1,996 Interest expense recognized 15,979 — Revenue interest payments ( 5,551 ) — Change in fair value — ( 906 ) Revenue interest liability at December 31, 2022 140,351 1,090 Interest expense recognized 5,060 — Revenue interest payments ( 2,883 ) — Revenue interest liability settlement ( 192,694 ) — Loss (gain) from termination of revenue interest purchase agreement 50,166 ( 1,090 ) Revenue interest liability at December 31, 2023 $ — $ — The net loss from termination of the RIPA of $ 49.1 million, comprised of the $ 50.2 million loss related to the settlement of the revenue interest liability and the $ 1.1 million gain on the derecognition of the related derivative liability, was recorded in the accompanying consolidated statements of operations. As of December 31, 2023, there were no outstanding balances related to the revenue interest liability and the derivative liability.

Asset Acquisitions

Asset Acquisitions	12 Months Ended
	Dec. 31, 2023
Asset Acquisitions [Abstract]
Asset Acquisitions	7. Asset Acquisitions Asset Purchase Agreement with Travere Therapeutics, Inc. On August 31, 2023, the Company completed the Bile Acid Portfolio Acquisition. In accordance with the terms and conditions of the Purchase Agreement, the Company purchased from Travere substantially all of the assets related to its business of development, manufacturing (including synthesis, formulation, finishing or packaging) and commercialization of the Bile Acid Medicines. The Company paid $ 210.4 million upon closing of the transaction, and up to an additional $ 235.0 million is payable upon the achievement of certain milestones based on specified amounts of annual net sales of the Bile Acid Medicines. The Company assessed the fair value of this contingent consideration in its determination of whether the acquisition of the Bile Acid Portfolio should be accounted for as an asset acquisition. The Company estimated the fair value of the contingent consideration using a Monte Carlo simulation model, which includes the amount and timing of revenue projections subsequent to the acquisition date as a significant assumption. The Company and Travere concurrently entered into a transitional services agreement pursuant to which Travere is obligated to perform certain services for a period of time, not anticipated to last beyond 12 months post-close, with respect to the Company’s use and operation of the assets purchased. The Company accounted for the transaction as an asset acquisition as substantially all the fair value of the gross assets acquired was concentrated in a group of similar identifiable assets, namely, the developed technology related to the Bile Acid Medicines. The developed technology asset consists of certain processes and at-market contracts related to the manufacture and commercialization of the Bile Acid Medicines, regulatory approvals, and other assets, and are considered a single asset as they are interdependently linked. The Company estimated the fair value of the developed technology asset using the discounted cash flow method. This approach incorporates significant estimates and assumptions related to the forecasted results including, but not limited to, estimates and assumptions regarding revenues, expenses, and discount rates to estimate future cash flows. The Company determined that the developed technology asset acquired was commercially viable and the cost of the acquisition was recorded as an intangible asset in the accompanying consolidated balance sheet as of December 31, 2023. The acquired assets are amortizable for tax purposes. The Company is obligated to pay tiered royalties, based on licensing agreements acquired with the Bile Acid Medicines, with rates ranging from high single digit to mid-teens based on net sales of the Bile Acid Medicines. The following represents the consideration paid and allocation of the purchase price for the acquisition of the Bile Acid Medicines (in thousands): Cash consideration $ 210,378 Transaction costs 2,384 Total purchase consideration 212,762 Assets acquired: Inventory 12,900 Intangible assets - developed technology 198,513 Intangible assets - assembled workforce 970 Other current and noncurrent assets 379 Total assets acquired $ 212,762 The Company amortizes the acquired intangible assets straight-line over their estimated useful lives of 12.5 years for developed technology and 3 years for assembled workforce (Note 2). Assignment and License Agreement with Shire International GmbH (Takeda) In November 2018, the Company entered into an Assignment and License Agreement (the “Shire Agreement”) with Shire International GmbH (“Shire”), which was subsequently acquired by Takeda Pharmaceutical Company Limited (“Takeda”). Under the terms of the Shire Agreement, Shire granted the Company an exclusive, royalty bearing worldwide license to develop and commercialize its two product candidates, Livmarli and volixibat. As part of the Shire Agreement, the Company was assigned license agreements held by Shire with Satiogen, Pfizer Inc. (“Pfizer”) and Sanofi-Aventis Deutschland GmbH (“Sanofi”). The Company has the right to sublicense under the Shire Agreement and additionally has the right to sublicense under the Satiogen, Pfizer and Sanofi licenses subject to the terms of those license agreements. The Company is obligated to pay Shire up to an aggregate of $ 109.5 million upon the achievement of certain clinical development and regulatory milestones for Livmarli in certain indications and an additional $ 25.0 million upon regulatory approval of Livmarli for each and every other indication. In addition, the Company is required to pay up to an aggregate of $ 30.0 million upon the achievement of certain clinical development and regulatory milestones for volixibat solely for the first indication sought. Upon commercialization, the Company is obligated to pay Shire product sales milestones on total licensed products up to an aggregate of $ 30.0 million. The Company is also obligated to pay tiered royalties with rates ranging from low double-digits to mid-teens based upon annual worldwide net sales for all licensed products; however, these royalties are reduced in part by royalties due under the Satiogen and Sanofi licenses, as discussed below, related to Livmarli and volixibat, as applicable. The Company’s royalty obligations will continue on a licensed product-by-licensed product and country-by-country basis until the later to occur of the expiration of the last valid claim in a licensed patent covering the applicable licensed product in such country, expiration of any regulatory exclusivity for the licensed product in a country and ten years after the first commercial sale of a licensed product in such country. As of December 31, 2022, the Company accrued $ 15.0 million for a regulatory milestone associated with approval of Livmarli by the European Commission for the treatment of cholestatic pruritus in patients with ALGS two months of age and older, which was paid by the Company in January 2023. In September 2023, the Company accrued $ 5.0 million for a commercial milestone associated with product sales, which was paid by the Company in December 2023. No additional milestones were accrued as of December 31, 2023 as there were no potential milestones yet considered probable. There were no volixibat development and regulatory milestones achieved during the years ended December 31, 2023 and 2022. On March 13, 2024, the Company received regulatory approval for Livmarli for the treatment of cholestatic pruritus in patients with PFIC five years of age and older by the FDA for marketing in the U.S. In connection with this approval, the Company will accrue and pay a $ 10.0 million regulatory milestone under this license agreement. Satiogen License Through the Shire Agreement, the Company was assigned a license agreement with Satiogen pursuant to which the Company obtained an exclusive, worldwide license to certain patents and know-how, with the right to sublicense to a third party subject to certain financial considerations. Pursuant to the terms of the license agreement, the Company was obligated to pay to Satiogen up to an aggregate of $ 10.5 million upon the achievement of certain milestones, of which $ 0.5 million was for initiation of certain development activities, $ 5.0 million for the completion of regulatory approvals and $ 5.0 million for commercialization activities. Additionally, the Company was required to pay a low single-digit royalty on net sales. The Company’s royalty obligations continued on a licensed product-by-licensed product and country-by-country basis until the expiration of the last valid claim in a licensed patent covering the applicable licensed product in such country. Royalty obligations under the Satiogen license were creditable against the royalty obligations to Shire under the Shire Agreement. The Company has not paid milestone payments pursuant to this agreement for the periods presented. In May 2022, the Company completed the merger and acquisition of Satiogen for total consideration of approximately $ 24.2 million. At acquisition, Satiogen’s assets consisted of cash and intangible assets related to developed technology. The purchase consideration consisted of 609,305 shares of the Company’s common stock issued upon the closing of the acquisition and cash consideration of $ 2.6 million, excluding $ 0.2 million of stock option exercise prices deemed to have been paid immediately prior to the acquisition, in respect of an equivalent amount of cash on the books of Satiogen, with up to an additional 32,494 shares of common stock that would have been issued upon the closing of the acquisition except the parties agreed to such shares being held back by the Company for 12 months from the acquisition date to satisfy certain purchase price adjustments and indemnification obligations that may arise during this period. Specifically, purchase price adjustments and indemnification obligations that arise will reduce the number of shares issuable by the Company at settlement in accordance with the terms of the definitive acquisition agreement. The purchase consideration also included issuance of up to an additional 199,993 shares of the Company’s common stock, contingent upon the achievement of a certain milestone by June 30, 2025, subject to adjustment to satisfy certain purchase price adjustments and indemnification obligations that may arise. In December 2022, with the approval of Livmarli by the European Commission for the treatment of cholestatic pruritus in patients with ALGS two months of age and older, the milestone was achieved and the Company issued 199,993 shares of common stock in January 2023. Additionally, in June 2023, the contingencies related to the held back shares were resolved and the Company issued 31,631 shares of common stock. Through the transaction, the Company obtained all Satiogen licensing payments and Satiogen-owned intellectual property relating to Livmarli and volixibat. The transaction resulted in a reduction of total licensing royalty obligations for Livmarli and volixibat. The Company accounted for the transaction as an asset acquisition as the set of acquired assets did not constitute a business and substantially all the fair value of the gross assets acquired was concentrated in a group of similar identifiable assets, namely, the Satiogen intangible assets consisted of intellectual property. The Company evaluated that the intellectual property assets acquired were deemed to be commercially viable and the cost of the acquisition was recorded as an intangible asset. There was no gain or loss recognized from settlement of the preexisting contractual relationship with Satiogen as the pre-existing contract was determined to be at fair value on the date of acquisition. Through the date of settlement in June 2023, there were no significant expenses incurred that were approved for settlement against the Indemnification Holdback. As the number of shares potentially issuable upon the resolution of the Indemnification Holdback and the Contingent Milestone was variable, they were recorded as liabilities at their respective fair values on the date of acquisition using the Company’s common stock price. The fair value of the Indemnification Holdback was additionally determined based on management’s estimate of the probability of indemnification obligations being incurred during the one year following the acquisition date, while the fair value of the Contingent Milestone was additionally determined based upon management’s estimate of the probability of the milestone being met until the contingency was resolved in December 2022. The fair value of the Indemnification Holdback liability and the Contingent Milestone liability were remeasured at each reporting period until settled, with resulting changes in the fair value recorded in other income (expense) in the accompanying consolidated statements of operations. The following represents the consideration paid and allocation of purchase price for the acquisition of Satiogen (in thousands, except per share data): Issued common stock $ 15,585 Cash consideration 2,600 Indemnification Holdback 831 Contingent consideration settled in common stock 4,600 Transaction costs 545 Total purchase consideration 24,161 Assets acquired: Intangible assets - developed technology 21,561 Cash consideration 2,600 Total assets acquired $ 24,161 Pfizer License Through the Shire Agreement, the Company was assigned a license agreement with Pfizer pursuant to which the Company obtained an exclusive, worldwide license to certain Pfizer know-how with a right to sublicense. Upon commercialization of any product utilizing the licensed product, the Company will be required to pay to Pfizer a low single-digit royalty on net sales of product sold by the Company, its affiliates or sublicensees. The Company’s royalty obligations continue on a licensed product-by-licensed product basis until the eighth anniversary of the first commercial sale of such licensed product anywhere in the world. Sanofi License Through the Shire Agreement, the Company was assigned a license agreement with Sanofi pursuant to which the Company obtained an exclusive, worldwide license to certain patents and know-how with the right to sublicense to a third party subject to certain financial considerations. The Company is obligated to pay up to an aggregate of $ 36.0 million upon the achievement of certain regulatory, commercialization and product sales milestones. Additionally, upon commercialization, the Company is required to pay tiered royalties in the mid to high single-digit range based upon net sales of licensed products sold by the Company and sublicensees in a calendar year, subject to adjustments in certain circumstances. The Company’s royalty obligations continue on a licensed product-by-licensed product and country-by-country basis until the later to occur of the expiration of the last valid claim in a licensed patent covering the applicable licensed product in such country and ten years after the first commercial sale of a licensed product in such country. Royalty obligations under the Sanofi license are creditable against the royalty obligations to Shire under the Shire Agreement. The Company has not paid milestone payments pursuant to this agreement for the periods presented. As of December 31, 2023 , no milestones had been accrued as there were no potential milestones considered probable.

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	8. Collaboration and License Agreements License and Collaboration Agreement with CANbridge In April 2021, the Company entered into an exclusive license and collaboration agreement with CANbridge Pharmaceuticals, Inc. (“CANbridge”). Under the terms of the agreement, CANbridge has obtained the exclusive right to develop and commercialize Livmarli within the Greater China regions (China, Hong Kong, Macau and Taiwan). In connection with the agreement, the Company received an upfront payment of $ 11.0 million, which, upon satisfaction of the performance obligation and receipt by CANbridge of the right to use and benefit from the license in May 2021, was recorded as license revenue. Additionally, the Company is eligible to receive up to $ 5.0 million in research and development funding, and up to $ 109.0 million for the achievement of future regulatory and commercial milestones, with double-digit tiered royalties based on product net sales. The Company concluded at inception of the agreement that the transaction price should not include the variable consideration related to unachieved developmental and regulatory milestones as this consideration was considered to be constrained as it is probable that the inclusion of such variable consideration could result in a significant reversal in cumulative revenue. The Company will recognize any consideration related to sales-based payments when the related sales occur, as the Company has determined that these amounts relate predominantly to the license granted and therefore will be recognized at the later of (i) when or as the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company re-evaluates the transaction price at each reporting period as uncertain events are resolved and other changes in circumstances occur. In January 2022 and June 2023, CANbridge achieved regulatory milestones, triggering milestone payments to the Company of $ 2.0 million and $ 5.0 million, respectively, which, upon the release of the constraints, were recorded as license revenue in the accompanying consolidated statements of operations for the years ended December 31, 2023 and 2022. For the years ended December 31, 2023, 2022 and 2021 , the Company recorded research and development funding of $ 2.3 million, $ 0.9 million and $ 1.9 million, respectively, payable by CANbridge to the Company which is reflected as a reduction of research and development expense in the accompanying consolidated statements of operations. As of December 31, 2023 and 2022, such research and development funding included in accounts receivable on the accompanying consolidated balance sheets was immaterial. License and Collaboration Agreement with GC Biopharma In July 2021, the Company entered into an exclusive license and collaboration agreement with GC Biopharma. Under the terms of the agreement, GC Biopharma has obtained the exclusive right to develop and commercialize Livmarli within South Korea for ALGS, PFIC, and biliary atresia (“BA”). In connection with the agreement, the Company received a $ 5.0 million upfront payment, which, upon satisfaction of the performance obligation and receipt by GC Biopharma of the right to use and benefit from the license, was recorded as license revenue. Additionally, the Company is entitled to certain research and development funding and up to $ 23.0 million for the achievement of future regulatory and commercial milestones, with double-digit tiered royalties based on product net sales. At inception of the agreement, the Company concluded that the transaction price should not include the variable consideration related to unachieved developmental and regulatory milestones as this consideration was considered to be constrained as it is probable that the inclusion of such variable consideration could result in a significant reversal in cumulative revenue for this contract when the uncertainty is resolved in the future. The Company will recognize any consideration related to sales-based payments (including milestones and royalties) when the related sales occur, as the Company has determined that these amounts relate predominantly to the license granted and therefore will be recognized on the later to occur of satisfaction of the performance obligation or the occurrence of the related sales. The Company re-evaluates the transaction price at each reporting period as uncertain events are resolved and other changes in circumstances occur. In February 2023, GC Biopharma achieved a regulatory milestone under this agreement triggering a milestone payment to the Company of $ 2.5 million, which upon the release of the constraint was recognized as license revenue in the accompanying consolidated statements of operations for the year ended December 31, 2023. For the years ended December 31, 2023, 2022 and 2021, research and development funding payable by GC Biopharma to the Company, which is reflected as a reduction of research and development expense in the accompanying consolidated statements of operations, was immaterial. As of December 31, 2023 and 2022, such research and development funding recorded as a receivable in accounts receivable on the accompanying consolidated balance sheets was immaterial. Licensing Agreement with Takeda In September 2021, the Company entered into an exclusive licensing agreement with Takeda for the development and commercialization of Livmarli in Japan for ALGS, PFIC, and BA. Under the terms of the agreement, Takeda will be responsible for regulatory approval and commercialization of Livmarli in Japan. Takeda will also be responsible for development, including conducting clinical studies in cholestatic indications. The Company is responsible for commercial supply to Takeda. In exchange, the Company is eligible to receive a percentage of Takeda’s annualized net sales, which range from high double digits declining to mid double digits over the first four years from commercial launch and thereafter remains at mid double digits. The Company fully constrained all revenues upon transfer of control of the license to Takeda, which occurred when Takeda could use and benefit from the license, and will recognize any consideration related to sales-based payments when the related sales occur, as the Company has determined that these amounts relate predominantly to the license granted and therefore will be recognized on the later to occur of satisfaction of the performance obligation or the occurrence of the related sales.

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	9. Leases In January 2019, the Company entered into an operating lease agreement for office space which consisted of approximately 5,600 square feet (the “Initial Lease”). The lease term is approximately four year s with an option to extend the term for one five-year term, which at the time was not reasonably assured of exercise and therefore, not included in the lease term. The lease contained a tenant improvement allowance of $ 0.4 million, which has been recorded as leasehold improvements on the accompanying consolidated balance sheets with a corresponding reduction of the ROU asset at inception of the lease. Rent payments commenced in August 2019. In November 2019, the Company amended the operating lease agreement (the “Amended Agreement”) to extend the term of the Initial Lease through March 2025. This extension was accounted for as a lease modification and the Company recorded an increase to the ROU asset and lease liability of $ 0.6 million at the time of the amendment. Additionally, pursuant to the Amended Agreement, the Company expanded the office space by 5,555 square feet for a five-year term expiring in March 2025 (the “Expanded Space”). The Company accounted for the Expanded Space as a separate contract as there were material additional rights of use that were not included in the Initial Lease. The Amended Agreement contained a tenant improvement allowance of $ 0.8 million in connection with the expanded space, which has been recorded as leasehold improvements within property and equipment, net on the accompanying consolidated balance sheets with a corresponding reduction of the ROU asset at inception of the lease for the expanded space. The ROU and corresponding lease liabilities were estimated using a weighted-average incremental borrowing rate of 8.0 %. As of December 31, 2023, the Company recorded an aggregate ROU asset of $ 1.3 million and an aggregate lease liability of $ 1.7 million in the accompanying consolidated balance sheets. The weighted-average remaining lease term is 2.1 years. As of December 31, 2023, undiscounted future minimum payments under the Company’s operating leases are as follows (in thousands): Years Ended December 31, Undiscounted 2024 $ 1,193 2025 366 2026 123 2027 123 2028 61 Total undiscounted lease payments 1,866 Less: imputed interest ( 145 ) Total lease liability $ 1,721 Rent expense was $ 0.8 million for each of the years ended December 31, 2023 and 2022 , and $ 0.7 million for the year ended December 31, 2021. Variable lease payments for each of the years ended December 31, 2023 and 2022 were $ 0.2 million. Variable lease payments for the year ended December 31, 2021 were immaterial. On January 17, 2024, the Company entered into an operating lease agreement for approximately 36,300 square feet of office space (the “New Lease”). The lease term is approximately five years and the Company will be paying approximately $ 10.8 million in base rent during the term. The Company expects the New Lease to commence in May 2024. Concurrently with entering into the New Lease, the Company entered into an amendment of its existing Amended Agreement to accelerate the lease expiration date from March 2025 to shortly after the commencement date of the New Lease. As of the date these financial statements are issued, the Company has not finalized the accounting for the amendment of its Amended Agreement or the New Lease.

Convertible Notes

Convertible Notes	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Convertible Notes	10. Convertible Notes In April 2023, the Company issued $ 316.3 million aggregate principal amount of its 4.00 % Convertible Senior Notes due 2029 (the "Notes") in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. The Notes are subject to the terms and conditions of an Indenture (the “Indenture”) between the Company and U.S. Bank Trust Company, National Association, as trustee. The net proceeds from the issuance of the Notes were $ 305.3 million, after deducting the initial purchasers’ discounts and commissions and offering expenses. The Notes are the Company’s senior, unsecured obligations and are (i) senior in right of payment to any of the Company’s indebtedness that is expressly subordinated to the Notes in right of payment; (ii) equal in right of payment to any of the Company’s indebtedness that is not so subordinated; (iii) effectively subordinated to any of the Company’s secured indebtedness, to the extent of the value of the collateral securing that indebtedness; and (iv) structurally subordinated to all indebtedness and other liabilities, including trade payables, and (to the extent the Company is not a holder thereof) preferred equity, if any, of the Company’s subsidiaries. The Notes accrue interest at a rate of 4.00 % per annum, payable semi-annually in arrears on May 1 and November 1 of each year, beginning on November 1, 2023. The Notes will mature on May 1, 2029, unless earlier converted, redeemed or repurchased by the Company. Before January 2, 2029, noteholders will have the right to convert their Notes only in the following circumstances: (i) during any calendar quarter (and only during such calendar quarter) commencing after the calendar quarter ending on June 30, 2023, if the last reported sale price per share of the Company’s common stock exceeds 130 % of the conversion price for the Notes for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; (ii) 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 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 common stock on such trading day and the conversion rate on such trading day; (iii) upon the occurrence of certain corporate events or distributions on the common stock, as described in the Indenture; and (iv) if the Company calls such Notes for redemption. Additionally, noteholders will have the right to convert their Notes at any time from January 2, 2029 until the close of business on the scheduled trading day immediately before the maturity date. The Company may settle conversions by paying or delivering, as applicable, cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. The initial conversion rate for the Notes is 31.5075 shares of common stock per $ 1,000 principal amount of Notes, which represents an initial conversion price of approximately $ 31.74 per share of common stock. The conversion rate and conversion price will be subject to customary adjustments upon the occurrence of certain events. In addition, if certain corporate events that constitute a “Make-Whole Fundamental Change” (as defined in the Indenture) occur, then the conversion rate will, in certain circumstances, be increased for a specified period of time. The Company may not redeem the Notes at its option at any time before May 5, 2026. The Notes are redeemable, in whole or in part (subject to the partial redemption limitation described below), at the Company’s option at any time, and from time to time, on or after May 5, 2026 and, in the case of a partial redemption, on or before the 50th scheduled trading day immediately before the maturity date, at a cash redemption price equal to the principal amount of the 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 (i) 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 (ii) the trading day immediately before the date the Company sends such notice. In addition, calling any Note for redemption will constitute a Make-Whole Fundamental Change with respect to that Note, in which case the conversion rate applicable to the conversion of that Note will be increased in certain circumstances if it is converted after it is called for redemption. Pursuant to the partial redemption limitation, the Company may not elect to redeem less than all of the outstanding Notes unless at least $ 75.0 million aggregate principal amount of Notes are outstanding and not called for redemption as of the time the Company sends the related redemption notice. If a “Fundamental Change” (as defined in the Indenture) occurs, then, subject to a limited exception for certain cash mergers, noteholders may require the Company to repurchase their Notes at a cash repurchase price equal to the principal amount of the Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date. The definition of Fundamental Change includes certain business combination transactions involving the Company and certain de-listing events with respect to the Company's common stock. The Indenture contains customary events of default with respect to the Notes and provides that upon certain events of default occurring and continuing, the Trustee may, and the Trustee at the request of holders of at least 25 % in principal amount of the Notes shall, declare all principal and accrued and unpaid interest, if any, of the Notes to be due and payable. In case of certain events of bankruptcy, insolvency or reorganization, involving the Company or a significant subsidiary, all of the principal of and accrued and unpaid interest on the Notes will automatically become due and payable. As of December 31, 2023, the Notes consisted of the following (in thousands): Convertible Notes Principal amount $ 316,250 Unamortized debt discount and issuance costs ( 9,829 ) Net carrying amount $ 306,421 The Company incurred $ 10.9 million of transaction costs related to the issuance of the Notes, which are being amortized to interest expense over the term of the Notes using the effective interest method. As of December 31, 2023 , the remaining amortization period of the debt discount was approximately 5.3 years and the effective interest on the Notes was 4.6 %. The following table sets forth interest expense recognized related to the Notes (in thousands): Year Ended 2023 Coupon interest expense $ 8,925 Amortization of debt discount and issuance costs 1,120 Total interest expense on convertible notes $ 10,045 As of December 31, 2023 , the estimated fair value of the Notes was $ 387.3 million. The fair values were determined based on the quoted price of the convertible notes in an inactive market on the last trading day of the reporting period and has been classified as Level 2 in the fair value hierarchy.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Stockholders' Equity	11. Stockholders’ Equity Common Stock In August 2020, the SEC declared effective a registration statement on Form S-3 (“2020 Shelf Registration”) covering the sale of up to $ 300.0 million of the Company’s securities. Also, in August 2020, the Company entered into a sales agreement (“2020 Sales Agreement”) with SVB Securities LLC, recently acquired by Leerink Partners LLC (“Leerink”) pursuant to which the Company could elect to issue and sell, from time to time, shares of common stock having an aggregate offering price of up to $ 75.0 million under the 2020 Shelf Registration through Leerink acting as the sales agent and/or principal. During the year ended December 31, 2023, the Company issued and sold 658,206 shares of common stock pursuant to the 2020 Sales Agreement resulting in gross proceeds to the Company of $ 15.0 million. The net proceeds for the year ended December 31, 2023 to the Company after deducting sales commissions to SVB Securities and other issuance expenses were approximately $ 14.5 million. As of December 31, 2023, the Company has issued and sold an aggregate of 2,125,090 shares of common stock pursuant to the 2020 Sales Agreement resulting in aggregate gross proceeds to the Company of $ 43.7 million. The 2020 Shelf Registration expired in August 2023, and no further sales may be made under the 2020 Sales Agreement. In August 2022, the Company completed an underwritten public offering of its common stock pursuant to the 2020 Shelf Registration. The Company issued and sold 3,478,261 shares of common stock at a public offering price of $ 23.00 per share. In addition, the Company granted the underwriters an option, exercisable for 30 days, to purchase up to 521,739 additional shares of its common stock at the public offering price, less the underwriting discounts, commissions and offering expenses, which the underwriters exercised in full. The underwritten public offering, including the underwriters’ exercise of their option, resulted in net proceeds to the Company of $ 86.1 million after deducting underwriting discounts, commissions and offering expenses. On September 9, 2022, the Company filed an automatic shelf registration statement on Form S-3 with the SEC (the “2022 Shelf Registration”), which became effective upon filing, pursuant to which the Company registered for sale from time to time in one or more offerings an unlimited amount of any combination of the Company’s common stock, preferred stock, debt securities and warrants, so long as the Company continues to satisfy the requirements of a “well-known seasoned issuer” under SEC rules. This automatic shelf registration statement will remain in effect for up to three years from the date it became effective. As of December 31, 2023, the Company had not issued any securities pursuant to the automatic shelf registration statement. On August 31, 2023, in connection with and immediately prior to the closing of the Bile Acid Portfolio Acquisition, the Company completed the private placement of 8,000,000 shares of the Company’s common stock at a price per share of $ 26.25 , resulting in net proceeds of approximately $ 202.2 million. On November 2, 2023, the Company entered into a Sales Agreement (the “2023 Sales Agreement”) with Leerink and Cantor Fitzgerald & Co. (the “Sales Agents”), pursuant to which the Company may, from time to time, sell up to an aggregate amount of $ 200.0 million of its common stock through the Sales Agents in an “at-the-market” offering (the “ATM Offering”). The Company is not required to sell shares under the 2023 Sales Agreement. Sales of the Company’s common stock, if any, under the 2023 Sales Agreement may be made in any transactions that are deemed to be “at the market offerings” as defined in Rule 415 under the Securities Act. The Company will pay a given designated Sales Agent a commission of up to 3.0 % of the aggregate gross proceeds of any shares of common stock sold through such Sales Agent pursuant to the 2023 Sales Agreement. As of December 31, 2023, the Company had not issued any securities pursuant to the 2023 Sales Agreement. Common Stock Reserved for Issuance Common stock reserved for issuance is as follows: December 31, 2023 2022 Stock options, restricted stock units and performance stock units issued and outstanding 10,909,831 8,955,557 Reserved for future stock awards or option grants 2,230,264 1,596,947 Reserved for employee stock purchase plan 1,040,828 1,157,570 Common stock issuable upon conversion of convertible notes 9,964,247 — Common stock held back in connection with asset acquisition — 31,638 Common stock issuable as contingent consideration in connection with asset acquisition — 199,993 24,145,170 11,941,705

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	12. Stock-Based Compensation Equity Incentive Plans In November 2018, the Company adopted the 2018 Equity Incentive Plan (the “2018 Plan”), which permits the granting of stock awards and incentive and nonstatutory stock options to employees, directors and consultants of the Company. In July 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan became effective on July 17, 2019. Under the 2019 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other stock or cash-based awards to individuals who are then employees, officers, directors or consultants of the Company. Shares subject to outstanding awards under the 2018 Plan as of the effective date of the 2019 Plan that are subsequently canceled, forfeited or repurchased by the Company will be added to the shares reserved under the 2019 Plan. In addition, the number of shares of common stock available for issuance under the 2019 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2019 Plan, beginning with January 1, 2020 and ending with January 1, 2029 , by an amount equal to 5 % of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year or such lesser amount as determined by the Company’s board of directors. As of December 31, 2023 , 1,119,312 shares of common stock were available for issuance under the 2019 Plan. In March 2020, the compensation committee of the Company’s board of directors approved and adopted the 2020 Inducement Plan (the “2020 Inducement Plan”). Under the 2020 Inducement Plan, the Company may grant nonstatutory stock options, stock appreciation rights, restricted stock and restricted stock units to new employees entering into employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). At adoption, the 2020 Inducement Plan authorized 750,000 shares of the Company’s common stock for future issuance. In 2023, 2021 and 2020, the Company’s board of directors authorized an additional 1,500,000 , 1,000,000 and 750,000 shares of the Company’s common stock for future issuance, respectively. As of December 31, 2023 , 1,110,952 shares of common stock were available for issuance under the 2020 Inducement Plan. Stock Options The following table summarizes stock option activity during the year ended December 31, 2023 (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2022 8,340,083 $ 13.63 7.5 $ 51,645 Granted 2,066,089 $ 25.35 Exercised ( 514,443 ) $ 16.09 Canceled and forfeited ( 259,225 ) $ 18.80 Outstanding as of December 31, 2023 9,632,504 $ 15.87 6.9 $ 131,785 Vested and exercisable as of December 31, 2023 5,978,571 $ 12.12 5.9 $ 104,048 Intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that had exercise prices that were lower than the per share fair value of the common stock on the date of exercise. The weighted-average grant date fair value per share of stock options granted during the years ended December 31, 2023, 2022 and 2021 was $ 18.25 , $ 12.73 and $ 13.39 per share, respectively. The total intrinsic value of options exercised during the years ended December 31, 2023, 2022 and 2021 was $ 5.7 million, $ 3.0 million and $ 1.3 million, respectively. As of December 31, 2023 , the total unrecognized stock-based compensation related to unvested stock option awards granted was $ 48.5 million, which the Company expects to recognize over a weighted-average period of approximately 2.6 years. The fair value of each employee and non-employee stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the expected stock price volatility was based upon the weighting of the Company’s historical volatility and the historical volatility of a peer group of publicly traded companies. The historical volatility data was computed using the daily closing prices for the Company’s and its peer companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. Due to the lack of historical exercise history, the expected term of the Company’s stock options for employees has been determined utilizing the “simplified” method for awards. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The following assumptions were used to estimate the fair value of stock option awards granted during the following periods: Year ended December 31, 2023 2022 2021 Expected term (in years) 5.3 - 6.1 5.5 - 6.1 5.5 - 6.1 Expected volatility 80.17 %- 85.24 % 80.86 %- 83.20 % 82.76 %- 94.06 % Risk-free interest rate 3.35 %- 4.67 % 1.46 %- 4.10 % 0.62 %- 1.34 % Expected dividend yield — — — Restricted Stock Units The following table summarizes the activity under the Company’s restricted stock units for the year ended December 31, 2023: Number of Weighted-Average Grant Date Fair Value per Award Unvested and outstanding as of December 31, 2022 615,474 $ 18.36 Granted 824,584 $ 25.48 Vested ( 245,783 ) $ 18.36 Cancelled/Forfeited ( 64,783 ) $ 20.82 Unvested and Outstanding as of December 31, 2023 1,129,492 $ 23.41 The fair value of restricted stock unit ("RSU") awards granted to employees and nonemployees is equal to the closing market price of the Company’s common stock on the grant date. As of December 31, 2023 , the total unrecognized stock-based compensation related to restricted stock unit awards granted was $ 19.6 million, which the Company expects to recognize over a weighted-average period of approximately 2.2 years. Performance Stock Units In January 2023, the Company granted an aggregate of 135,835 performance stock units to certain executive participants (“2023 Executive PSUs”). The 2023 Executive PSUs are subject to a performance condition of achieving certain net product sales levels related to Livmarli during the year ended December 31, 2024. If the performance condition is met, the first tranche of the award will vest on March 15, 2025 and the second tranche will vest on March 15, 2026, subject to the executive employees’ continuous service through each vesting date. The number of units to be vested in the first tranche of the 2023 Executive PSUs is calculated by multiplying two-thirds of the 2023 Executive PSUs granted by a percentage calculated based on attained Livmarli sales metrics, as certified by the Company’s Compensation Committee. The number of units to be vested in the second tranche of the 2023 Executive PSUs equals 50 % of the units vested in the first tranche. In June 2023, the Company granted an aggregate of 12,000 PSUs to certain employees ("2023 Employee PSUs"). The 2023 Employee PSUs are subject to a performance condition of achieving certain net product sales related to Livmarli in the US for the year ended December 31, 2023. The following table summarizes the activity under the Company's performance stock units for the year ended December 31, 2023: Number of Weighted-Average Grant Date Unvested and outstanding as of December 31, 2022 — $ — Granted 147,835 $ 23.64 Unvested and outstanding as of December 31, 2023 147,835 $ 23.64 As of December 31, 2023 , the total unrecognized stock compensation related to performance stock units granted was $ 2.1 million, which the Company expects to recognize over a weighted-average period of approximately 1.5 years. 2019 Employee Stock Purchase Plan In July 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Employee Stock Purchase Plan (“ESPP”). T he number of shares of common stock available for issuance under the ESPP will be automatically increased on the first day of each calendar year during the first ten years of the term of the ESPP, beginning with January 1, 2020 and ending with January 1, 2029 , by an amount equal to the lesser of (i) 1 % of the outstanding number of shares of common stock on December 31st of the preceding calendar year, (ii) 1,500,000 shares of common stock or (iii) such lesser amount as determined by the Company’s board of directors. The ESPP became effective on July 17, 2019 and generally provides for six-month consecutive offering periods beginning on May 11th and November 11th of each year. During the year ended December 31, 2023 , 116,742 shares were issued under the ESPP. As of December 31, 2023 , the Company had 1,040,828 shares available for future issuance under the ESPP. The stock-based compensation related to the ESPP for the years ended December 31, 2023, 2022 and 2021 was $ 0.9 million, $ 0.7 million and $ 0.7 million, respectively. Restricted Common Stock In November 2018, in connection with the issuance of Series A Preferred Stock, the Company’s founders agreed to modify their outstanding shares of common stock to include vesting provisions that require continued service to the Company in order to vest in those shares. As such, the 562,500 modified shares of common stock became compensatory upon such modification. During the years ended December 31, 2022 and 2021, 122,464 shares and 133,593 shares vested, respectively. All restricted common stock was fully vested as of December 31, 2022. Compensation Expense Total stock-based compensation is reflected in the accompanying consolidated statements of operations as follows (in thousands): Year Ended December 31, 2023 2022 2021 Selling, general and administrative $ 24,131 $ 16,957 $ 13,128 Research and development 10,892 10,050 9,888 Total $ 35,023 $ 27,007 $ 23,016 Stock-based compensation reflected in cost of goods sold for the years ended December 31, 2023, 2022 and 2021 was insignificant. Stock-based compensation of $ 0.8 million, $ 0.4 million and $ 0.1 million was capitalized into inventory for the years ended December 31, 2023, 2022 and 2021 , respectively.

Gain from Sale of Priority Revi

Gain from Sale of Priority Review Voucher	12 Months Ended
	Dec. 31, 2023
Gain (Loss) on Sale of Investments [Abstract]
Gain from Sale of Priority Review Voucher	13. Gain from Sale of Priority Review Voucher In November 2021, the Company entered into a definitive agreement to sell the PRV that it received from the FDA in connection with the approval of Livmarli for the treatment of cholestatic pruritus in patients with ALGS one year of age and older, for cash proceeds of $ 110.0 million. In December 2021, the Company completed its sale of the PRV and received net proceeds of $ 108.0 million, after deducting commission costs, which was recorded as a gain within other income (loss) in the accompanying consolidated statements of operations.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes The Company’s losses before provision for income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 2021 U.S. loss before taxes $ ( 164,953 ) $ ( 142,661 ) $ ( 84,217 ) Foreign income before taxes 2,529 590 266 Loss before income taxes $ ( 162,424 ) $ ( 142,071 ) $ ( 83,951 ) The income tax (expense) benefit applicable to income before income taxes consists of the following: Year Ended December 31, 2023 2022 2021 Current income taxes: Federal $ 37 $ — $ — State 67 18 — Foreign 887 157 37 Total current 991 175 37 Deferred taxes: Federal — ( 5,503 ) — State — ( 1,078 ) — Total deferred — ( 6,581 ) — Income tax (benefit) expense $ 991 $ ( 6,406 ) $ 37 The Company acquired Satiogen in a tax-free reorganization, whereby the Company did not receive a step-up in tax basis of the acquired intangible assets, resulting in a deferred tax liability of $ 6.6 million. The deferred tax liability provided an additional source of taxable income to support the realization of the pre-existing deferred tax assets. As a result, a portion of the Company’s valuation allowance was released and a $ 6.6 million tax benefit was recorded for the year ended December 31, 2022. A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2023 2022 2021 Federal statutory income tax rate 21.00 % 21.00 % 21.00 % State tax 3.57 7.40 1.32 Permanent differences ( 0.50 ) ( 0.65 ) ( 1.70 ) Other ( 0.13 ) ( 0.93 ) 0.02 Executive compensation — ( 2.99 ) — Global intangible low-taxed income ( 1.69 ) ( 1.43 ) — Tax credits 1.91 4.96 7.72 Change in valuation allowance ( 24.77 ) ( 22.85 ) ( 28.41 ) Total tax benefit ( 0.61 ) % 4.51 % ( 0.05 ) % The significant components of the Company’s deferred taxes are as follows (in thousands): December 31, 2023 2022 Deferred tax assets: Net operating losses $ 40,455 $ 34,522 Capitalized research and development 38,065 23,569 Tax credit carryforwards 30,071 26,747 Interest limitation attributes 15,814 3,127 Stock-based compensation 8,419 6,726 Intangibles 4,055 4,733 Accrued expenses 3,953 3,101 Inventory 2,316 426 Lease liability 269 460 Total deferred tax assets 143,417 103,411 Deferred tax liabilities: Operating lease right-of-use assets ( 161 ) ( 272 ) Fixed assets ( 37 ) ( 100 ) Total deferred tax liabilities ( 198 ) ( 372 ) Valuation allowance ( 143,219 ) ( 103,039 ) Net deferred tax assets $ — $ — The valuation allowance increased by $ 40.2 million, $ 32.5 million and $ 23.9 million for the years ended December 31, 2023, 2022 and 2021, respectively. The tax benefit of deductible temporary differences or carryforwards is recorded as a deferred tax asset to the extent that management assesses the realization is “more likely than not.” Future realization of the tax benefit ultimately depends on the existence of sufficient taxable income within the period available under the tax law. At December 31, 2023 and 2022, the Company has set up valuation allowances against all federal and state net deferred tax assets, because based on all available evidence, these deferred tax assets are not more than likely to be realizable. The Company had federal, California and other state net operating loss carryforwards of approximately $ 166.9 million, $ 30.0 million and $ 59.7 million at December 31, 2023 , and $ 153.1 million, $ 19.1 million and $ 17.7 million at December 31, 2022 , respectively. Federal losses do not expire, and California net operating and other state income net operating losses will begin to expire in 2038 and 2032 , respectively, if not utilized. The Company also has federal general business credit and California research and development credit carryforwards totaling $ 36.5 million and $ 4.8 million at December 31, 2023 , and $ 32.5 million and $ 4.2 million at December 31, 2022, respectively. The federal research and development credit carryforwards will begin to expire in 2039, unless previously utilized. The California research credits do not expire. In general, if the Company experiences a greater than 50 percentage point aggregate change in ownership of certain significant stockholders over a three-year period (a “Section 382 ownership change”), utilization of its pre-change NOL carryforwards and the research and development credit carryforwards is subject to an annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, and similar state laws. The annual limitation generally is determined by multiplying the value of the Company’s stock at the time of such ownership change, subject to certain adjustments, by the applicable long-term tax-exempt rate. Such limitations may result in expiration of a portion of the NOL carryforwards and research and development credit carryforwards before utilization and may be material. As of December 31, 2023, the Company determined that it has not experienced an ownership change and determined that NOLs and tax credits are not subject to a limitation pursuant to Section 382. The Company recognizes the financial statements effects of a tax position when it is more likely than not, based on technical merits, that the position will be sustained upon examination. A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2023 2022 Balance at beginning of year $ 9,254 $ 6,399 (Decrease) related to prior year tax positions — — Increases related to current year tax positions 1,200 2,855 Balance at end of year $ 10,454 $ 9,254 The Company has considered the amounts and probabilities of the outcomes that can be realized upon ultimate settlement with the tax authorities and determined unrecognized tax benefits primarily related to credits should be established as noted in the summary roll-forward above. The Company does not expect that its uncertain tax positions will materially change in the next twelve months. The Company’s effective income tax rate would not be impacted if the unrecognized tax benefits were recognized in 2023 and 2022, as the Company is in a full valuation allowance position. The Company files federal, state and foreign income tax returns in jurisdictions with varying statutes of limitations. All of the Company’s tax returns in all jurisdictions remain open to examination since inception. The Company’s policy is to recognize interest expense and penalties related to income tax matters as tax expense. As of December 31, 2023 and 2022, there were no significant accruals for interest related to unrecognized tax benefits or tax penalties. The Company has no t provided U.S. income or foreign withholding taxes on the undistributed earnings of its foreign subsidiaries as of December 31, 2023 and 2022 , because it intends to permanently reinvest such earnings outside of the U.S. If these foreign earnings were to be repatriated in the future, the related U.S. tax liability will be immaterial, due to the participation exemption put in place in the Tax Act.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Certain of the Company's contractual arrangements with contract manufacturing organizations 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. The Company is subject to potential liabilities under government regulations and various claims and legal actions that are pending or may be asserted from time-to-time. These matters arise in the ordinary course and conduct of the Company’s business and may include, for example, commercial, intellectual property, and employment matters. The Company intends to defend itself vigorously in such matters and when warranted, take legal action against others. Furthermore, the Company regularly assesses contingencies to determine the degree of probability and range of possible loss for potential accrual in its financial statements. An estimated loss contingency is accrued in the Company’s financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. The Company does not accrue amounts for liabilities that it does not believe are probable. Litigation is inherently unpredictable, and unfavorable resolutions could occur. As a result, assessing contingencies is highly subjective and requires judgment about future events. During the periods presented, the Company has not recorded any accrual for loss contingencies associated with such government regulations, claims or legal actions, determined that an unfavorable outcome is probable or reasonably possible, or determined that the amount or range of any possible loss is reasonably estimable.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. The Company translates the financial statements of its foreign subsidiaries using end-of-period exchange rates for assets and liabilities and average exchange rates during each reporting period for results of operations. All intercompany balances and transactions among the consolidated entities have been eliminated in consolidation. The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in the financial statements and accompanying notes. These estimates and assumptions are based upon historical experience, knowledge of current events and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of expenses that are not readily apparent from other sources. Actual results could differ materially from those estimates. The Company’s consolidated financial statements as of and for the year ended December 31, 2023 reflect the Company’s estimates of the impact of the geopolitical and macroeconomic environment, including the impact of inflation, bank failures, high interest rates and foreign exchange rate fluctuations. The duration and the scope of these conditions cannot be predicted; therefore, the extent to which these conditions will directly or indirectly impact the Company’s business, results of operations and financial condition, is uncertain. The Company is not aware of any specific event or circumstance that would require an update to its estimates, judgments and assumptions or a revision of the carrying value of the Company’s assets or liabilities as of the date of this filing.
Cash Cash Equivalents and Restricted Cash Equivalents	Cash, Cash Equivalents and Restricted Cash Equivalents The Company considers all highly liquid investments that are readily convertible into cash without penalty and with original maturities of three months or less at the date of purchase to be cash equivalents. The carrying amounts reported in the consolidated balance sheets for cash and cash equivalents are valued at cost, which approximate their fair value. Restricted cash equivalents as of December 31, 2022 consisted of deposits placed in a segregated bank account as required under the terms of the Company’s RIPA, as amended in September 2021, with Mulholland SA LLC, an affiliate of Oberland Capital LLC (“Oberland”), as agent for the purchasers party thereto (the “Purchasers”), and the Purchasers in connection with the sale of the Priority Review Voucher in December 2021. Upon repurchase and the termination of the RIPA in April 2023, in accordance with its terms, the previously restricted cash equivalents of $ 100.0 million were no longer restricted from use. The following table provides a reconciliation of cash, cash equivalents and restricted cash equivalents reported within the consolidated balance sheets that together reflect the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 286,326 $ 28,003 Restricted cash equivalents — 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 286,326 $ 128,003
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, accounts receivable and investments. The Company limits the amount of credit exposure by investing cash that is not required for immediate operating needs in money market funds, government obligations and/or commercial paper with short maturities. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities, which are designed to maintain principal and maximize liquidity. To date, the Company has not experienced any losses associated with this credit risk and continues to believe that this exposure is not significant. The Company relies on a specialty pharmacy and a single distributor for all of the Company’s sales of Livmarli in the United States as well as a single distributor for sales outside the United States. The Company relies on a specialty pharmacy for all the Company’s sales of Chenodal and Cholbam in the United States. The Company sources materials and services through several vendors. Certain materials are sourced from a single vendor. The loss of certain vendors could result in a temporary disruption of the Company’s commercialization efforts. As of December 31, 2023 , the Company did no t have any customers that individually accounted for more than 10 % of accounts receivable. As of December 31, 2022 , the Company had one customer that accounted for approximately 23 % of accounts receivable. For the years ended December 31, 2023, 2022 and 2021 , the Company did not have revenue attributable to any one customer in excess of 10 % of sales.
Investments	Investments The Company classifies all investments in securities as available-for-sale. Management determines the appropriate classification of its investments in securities at the time of purchase. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than twelve months from the balance sheet date, are classified as a current asset. Investments are recorded at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized, with the exception of any declines in fair value below the cost basis that are a result of a credit loss, which, if any, are reported in other income (expense), net in the current period through an allowance for credit losses. Each reporting period, the Company evaluates whether declines in fair values of its available-for-sale securities below their cost basis are a result of credit loss or other factors and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss, the creditworthiness of the security issuers, as well as the Company’s ability and intent to hold the available-for-sale security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any available-for-sale securities before recovery of its amortized cost basis. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis and are also included in other income (expense). To date, the Company has no t identified any declines in fair value of its investments related to credit loss.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement determined based on assumptions that market participants would use in pricing an asset or liability. The following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: Level 1: Observable inputs (unadjusted) such as quoted prices in active markets for identical assets or liabilities; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly for similar assets or liabilities; and Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.
Accounts Receivable	Accounts Receivable The Company has accounts receivable amounts due from product sales. The Company also has accounts receivable amounts due from license agreements for milestones achieved, but not yet paid. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company estimates the allowance for credit losses using the current expected credit loss model. Under this model, the allowance for credit losses reflects the Company’s estimate of lifetime expected credit losses. The Company evaluates the collectability of the cash flows based on the risk of loss over the contractual life, even when that risk is remote, based on judgments about the creditworthiness of its customers, historical experience and other relevant information that is available to the Company. There was no allowance for credit losses as of December 31, 2023 . There was no bad debt expense for the years ended December 31, 2023, 2022 and 2021 .
Inventory	Inventory Inventory is valued at the lower of cost or net realizable value, with cost determined on a first-in, first-out (FIFO) basis. The Company periodically reviews the composition of inventory to identify excess, obsolete, slow-moving or otherwise unsaleable items. If unsaleable items are observed and there are no alternate uses for the inventory, the Company will record a write-down to net realizable value in the period that the decline in value is recognized through a charge to cost of sales. Furthermore, the Company periodically reviews its firm commitments for the purchase of minimum order quantities. If the minimum order quantities exceed the Company’s future demand, a net loss is accrued in cost of sales for such future inventory purchases. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required. Accruals for firm purchase commitments amounted to $ 5.2 million as of December 31, 2023, of which $ 3.8 million was included in other liabilities on the consolidated balance sheets. Prior to the initial regulatory approval for Livmarli, the Company expensed costs relating to raw materials and production of inventory as research and development expense in the accompanying consolidated statements of operations, in the period incurred. The Company has substantially depleted such inventories as of December 31, 2023.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets, ranging from three to five years . Leasehold improvements are amortized over the shorter of their useful lives or the related lease term. As of December 31, 2023 , property and equipment consisted primarily of leasehold improvements of $ 1.3 million and furniture and equipment of $ 0.9 million. As of December 31, 2022 , property and equipment consisted primarily of leasehold improvements of $ 1.3 million and furniture and equipment of $ 0.6 million. Accumulated depreciation as of December 31, 2023 and 2022 was $ 1.5 million and $ 1.0 million, respectively. Depreciation expense was $ 0.3 million for each of the years ended December 31, 2023, 2022 and 2021 .
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for indications of possible impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amounts to the future undiscounted cash flows attributable to these assets. An impairment loss is recognized to the extent an asset group is not recoverable, and the carrying amount exceeds the projected discounted future cash flows arising from these assets. There were no impairments of long-lived assets for any of the periods presented.
Intangibles Assets, Net	Intangible Assets, Net The Company accounts for asset acquisitions that do not meet the definition of a business using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the asset (or assets) acquired on the basis of its (or their) relative fair value(s) on the measurement date. No goodwill is recognized in an asset acquisition. Intangible assets are measured at their fair values as of the acquisition date or, in the case of commercial milestone payments, the date they become due. The evaluation of intangible assets includes assessing the amortization period for which the asset is expected to contribute to the future cash flows of the Company. Intangible assets with finite useful lives are amortized over their estimated useful lives, primarily on a straight-line basis when the Company is unable to reliably estimate the pattern of cash flow. The Company tests its finite lived intangible assets for impairment annually or if events or changes in circumstances indicate that it is more likely than not that the asset is impaired. If it is determined that the asset is impaired, the carrying value is written down to its estimated fair value, with the related impairment charge recognized in the consolidated statements of operations in the period in which the impairment occurs. The Company has not recorded any impairments to its intangible assets for any of the periods presented. The components of the Company’s intangible assets were as follows (in thousands, except for weighted-average remaining amortization period): December 31, 2023 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 39,000 $ ( 3,318 ) $ 35,682 16.2 Developed technology 226,620 ( 10,239 ) 216,381 11.7 Assembled workforce 970 ( 108 ) 862 2.7 Total intangible assets $ 266,590 $ ( 13,665 ) $ 252,925 12.3 December 31, 2022 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 34,000 $ ( 1,333 ) $ 32,667 17.1 Developed technology 28,107 ( 1,820 ) 26,287 8.4 Total intangible assets $ 62,107 $ ( 3,153 ) $ 58,954 11.9 Amortization expense was $ 10.5 million, $ 2.9 million and $ 0.3 million for the years ended December 31, 2023, 2022 and 2021, respectively, and was included in cost of sales on the accompanying consolidated statements of operations. The following table summarizes the estimated future amortization expense associated with the Company’s intangible assets as of December 31, 2023 (in thousands): Amount 2024 $ 21,545 2025 21,545 2026 21,436 2027 21,221 2028 21,221 Thereafter 145,957 $ 252,925
Leases	Leases The Company determines if a contractual arrangement is or contains a lease at inception. Operating lease right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset during the lease term, and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating leases are included in ROU assets, current operating lease liabilities, and long-term operating lease liabilities on the accompanying consolidated balance sheets. Operating lease ROU assets and lease liabilities are initially recognized based on the present value of the future minimum lease payments over the lease term at commencement date calculated using the Company’s incremental borrowing rate applicable to the leased asset, unless the implicit rate is readily determinable. Operating lease ROU assets also include any lease payments made at or before lease commencement and exclude any lease incentives received. The Company determines the lease term as the noncancelable period of the lease and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Leases with a term of 12 months or less are not recognized on the consolidated balance sheets. The Company’s leases do not contain any residual value guarantees. Lease expense for minimum lease payments is recognized as rent expense on a straight-line basis over the lease term. Variable lease payments include lease operating expenses.
Accrued Research and Development Expenses	Accrued Research and Development Expenses The Company accrues and expenses clinical trial activities performed by third parties based upon estimates of the proportion of work completed over the life of the individual study and patient enrollment rates in accordance with agreements established with clinical research organizations and clinical trial sites. The Company determines the estimates by reviewing contracts, vendor agreements and purchase orders and through discussions with internal clinical personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services. The Company makes estimates of accrued expenses as of each balance sheet date based on facts and circumstances known to the Company at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. The Company has not experienced any material differences between accrued costs and actual costs incurred for the periods presented. Nonrefundable advance payments for goods and services are deferred and recognized as expense in the period that the related goods are consumed or services are performed.
Convertible Notes	Convertible Notes The Company evaluates all conversion, repurchase and redemption features contained in a debt instrument to determine if there are any embedded features that require bifurcation as a derivative. The Company accounts for its convertible notes (refer to Note 10) as a long-term liability equal to the proceeds received from issuance, including any embedded conversion features, net of the unamortized debt discount and offering costs in the accompanying consolidated balance sheets. The debt issuance and offering costs are amortized over the contractual term of the convertible notes, using the effective interest method, as interest expense in the accompanying consolidated statements of operations.
Revenue Interest Liability, Net	Revenue Interest Liability, Net The revenue interest liability, net, associated with the RIPA that the Company entered into in December 2020, as amended in September 2021, with Oberland as agent for Purchasers, and the Purchasers, was presented net of issuance costs and a debt discount on the consolidated balance sheet as of December 31, 2022. The Company imputed interest expense associated with this liability using the effective interest rate method. The effective interest rate was calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on the liability varied during the term of the agreement depending on a number of factors, including the level of actual and forecasted product sales, net. The Company evaluated the interest rate quarterly based on actual product sales, net and forecast product sales, net, utilizing the prospective method. In April 2023, the Company repurchased all future Revenue Interests and as a result, the RIPA was terminated in accordance with its terms (refer to Note 6).
Derivative Liability	Derivative Liability The RIPA contained certain features that met the definition of being an embedded derivative requiring bifurcation as a separate compound financial instrument apart from the RIPA. The derivative liability was initially measured at fair value on issuance and was subject to remeasurement at each reporting period with changes in fair value recognized as other income (expense) in the accompanying consolidated statements of operations as the change in fair value of derivative liability. In April 2023, the derivative liability was extinguished in connection with the termination of the RIPA (refer to Note 6).
Revenue Recognition	Revenue Recognition The Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for those goods or services. Product Sales, Net The Company recognizes product sales, net when the customer obtains control of our product, which occurs at a point in time, typically upon delivery of the Company’s product to the customer. Revenues from product sales are recorded at the net sales price, or the transaction price, which may include fixed or variable consideration for discounts, government rebates, co-pay assistance, returns and other allowances that are offered within contracts with a customer relating to the sale of the Company's approved medicines. Estimates of variable consideration are calculated based on the actual product sales each reporting period and the nature of the variable consideration related to those sales. Overall, these estimates reflect the Company’s best estimate of the amount of consideration to which the Company expects to be entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in product sales, net only to the extent that it is considered probable that a significant reversal in the amount of the cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Estimates are reviewed and updated quarterly as additional information becomes known. Actual amounts of consideration ultimately received may differ materially from estimates. If actual results in the future vary from estimates, the Company will adjust these estimates, which would affect product sales, net and earnings in the period such variances are adjusted. Significant categories of sales discounts and allowances are as follows: Government Rebates : The Company records rebates payable under Medicaid and other government programs as a reduction of revenue at the time product revenues are generated. The Company’s rebate calculations may require estimates, including estimates of customer mix, to determine which sales will be subject to rebates and the amount of such rebates. The Company updates its estimates and assumptions on a quarterly basis and records any necessary adjustments to revenue in the period identified. The liability for unpaid rebates is included in accrued expenses on the accompanying consolidated balance sheets. To date, actual government rebates have not differed materially from the Company’s estimates. Other Incentives: Other incentives include a branded co-pay assistance program for eligible patients with commercial insurance in the United States. The branded co-pay assistance program assists commercially insured patients who have coverage for the Company's approved medicines and is intended to reduce each participating patient’s portion of the financial responsibility of the purchase price up to a specified dollar amount of assistance. The calculation of the accrual for co-pay assistance is based upon an identification of claims and the cost per claims associated with product that has been recognized as revenue. The Company records amounts paid under the brand specific co-pay assistance program for each patient as a reduction of revenue from product sales. To date, actual other incentives have not differed materially from the Company’s estimates. Product Returns: The Company records revenue for product sales, net of estimated product returns. Customers have limited return rights related only to the product’s damage or defect identified upon delivery of the product. The Company estimates the amount of product sales that may be returned and records the estimate as a reduction of revenue and a refund liability in the period the related product revenue is recognized. To date, actual returns have not differed materially from the Company’s estimates. The following table presents Total revenues and disaggregates Product sales, net by approved medicine (in thousands): Year Ended December 31, 2023 2022 2021 Product sales, net: Livmarli $ 141,795 $ 75,062 $ 3,138 Bile Acid Medicines 37,079 — — Total product sales, net 178,874 75,062 3,138 License revenue 7,500 2,000 16,000 Total revenues $ 186,374 $ 77,062 $ 19,138 The following table sets forth Product sales, net by geographic area based on the ship-to location (in thousands): Year Ended December 31, 2023 2022 2021 United States $ 146,699 $ 67,920 $ 2,913 Rest of world 32,175 7,142 225 Total product sales, net $ 178,874 $ 75,062 $ 3,138 License and Collaboration Arrangements The Company enters into collaborative arrangements with partners and analyzes the collaboration arrangements to assess whether they are within the scope of Collaborative Arrangements (Topic 808) ("Topic 808") and determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be subject to Revenue from Contracts with Customers (Topic 606) (“Topic 606”) for distinct units of account that are reflective of a vendor-customer relationship. For other elements of collaboration arrangements, such as reimbursements of certain development costs, the Company generally records reimbursements received as a reduction of research and development expenses. In determining the appropriate amount of revenue to be recognized under Topic 606 as the Company fulfills its obligations under each of its agreements, the Company performs the following steps: (i) identification of the contracts with customers; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) determination and measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations in the contract; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The terms of the Company’s license and collaborative research and development agreements include upfront license fees, research, development and other funding or reimbursements, milestone and other contingent payments for the achievement of defined collaboration objectives and certain development, regulatory and sales-based events, as well as royalties on sales of commercialized products. Arrangements that include upfront payments may require deferral of revenue recognition to a future period until the Company satisfies performance obligations under these arrangements. A performance obligation is a promise in a contract to transfer a distinct good or service and is the unit of accounting in Topic 606. A contract’s transaction price is allocated among each distinct performance obligation based on relative standalone selling price and recognized as revenue when, or as, the applicable performance obligation is satisfied. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price as variable consideration using the most likely amount method or expected value method, depending on the nature of the contingency and the variable payments. If it is probable that a significant reversal of cumulative revenue recognized for the contract would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not generally considered probable of being achieved until those approvals are received. Given the high degree of uncertainty around the occurrence of these events, the Company generally determines the milestone and other contingent amounts to be fully constrained until the uncertainty associated with these payments is resolved. At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, the Company recognizes revenue at the later of (i) when or as the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Accounting for these arrangements requires the Company to develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. The Company has never sold the performance obligations in its collaborative arrangements separately; therefore, an observable stand-alone selling price does not exist. Accordingly, the Company estimates a stand-alone selling price through maximizing the use of observable inputs such as market data, project cost estimates, and targeted margins. Cost of Product Sales Prior to receiving approval from the U.S. Food and Drug Administration ("FDA") or other foreign regulatory authorities for a new medicine or new formulation, the Company expenses all costs incurred related to the manufacture of such medicines as research and development expense because of the inherent risks associated with the development of a drug candidate, the uncertainty about the regulatory approval process and the lack of history for the Company of regulatory approval of drug candidates. Subsequent to receiving FDA or other foreign regulatory authority approval, when commercialization is considered probable and the future economic benefit is expected to be realized, the Company begins capitalizing inventory costs incurred. Cost of product sales consist of manufacturing costs, transportation and freight, amortization of capitalized intangible assets, royalties and indirect overhead costs associated with the manufacturing and distribution of the Company's approved products. Cost of product sales may also include period costs related to certain manufacturing services and inventory adjustment charges.
Research and Development Expenses	Research and Development Expenses Research and development expenses consists primarily of fees paid to contract research organizations and other vendors for clinical, non-clinical and manufacturing services, salaries and employee benefits, including stock-based compensation, consultant expenses, costs related to acquiring manufacturing materials, costs related to compliance with regulatory requirements and license payments related to acquiring intellectual property rights for the Company’s product candidates. Research and development expenses are expensed as incurred.
Selling, General and Administrative Expenses	Selling, General and Administrative Expenses Selling, general and administrative (“SG&A”) expenses relate to sales and marketing, finance, human resources, legal and other administrative activities. SG&A expenses consist primarily of personnel costs, facilities and overhead costs, outside marketing, advertising and legal expenses, and other general and administrative costs. The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $ 6.3 million, $ 4.0 million and $ 9.2 million for the years ended December 31, 2023, 2022 and 2021 , respectively.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes stock-based compensation for all stock-based awards based on the grant date fair value of the award granted to employees and nonemployees, including members of its board of directors. For stock-based awards with service conditions, the fair value of the awards is recognized on a straight-line basis over the requisite service period in which the awards are expected to vest. For stock-based awards with performance vesting conditions, stock-based compensation is recognized when it is considered probable that the performance conditions will be satisfied. At each reporting period, the Company reassesses the probability of the achievement of the performance vesting conditions. Any change in stock-based compensation resulting from an adjustment in the vesting is treated as a cumulative catch-up in the period of adjustment. For stock-based awards with market conditions, stock-based compensation is recognized over the appropriate requisite service period. The Company accounts for forfeitures as they occur. The Company evaluates the grant date fair value of awards granted for impacts of any potential material non-public information at the time of grant.
Foreign Currency	Foreign Currency The consolidated financial statements are presented in U.S. dollars. The functional currency for most of the Company’s foreign subsidiaries is their local currency. Balance sheet accounts of international subsidiaries are translated at the current exchange rates as of the end of each accounting period. Income statement items are translated at average exchange rates for the period. The resulting translation adjustments are recorded as a separate component of stockholders’ equity. Foreign currency transaction gains and losses are included in other income (expense), net in the consolidated statements of operations. Transaction gains and losses result primarily from fluctuations in exchange rates when intercompany receivables and payables are denominated in currencies other than the functional currency of our subsidiary that recorded the transaction. Unrealized foreign exchange losses amounted to $ 1.8 million for the year ended December 31, 2023, and were insignificant for the years ended December 31, 2022 and 2021. Realized foreign exchange gains and losses were insignificant for the years ended December 31, 2023, 2022 and 2021.
Income Taxes	Income Taxes Income taxes are recorded using the liability method, under which deferred tax assets and liabilities are determined based on differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are recorded against deferred tax assets, including net operating losses and tax credits, when it is determined it is more-likely-than-not that some or all of the tax benefits will not be realized. The Company accounts for uncertain tax positions in accordance with the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification No. 740, Income Taxes (“ASC 740”). When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit would more likely than not be realized assuming examination by the taxing authority. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. Interest and penalties related to unrecognized tax benefits, if any, are recorded as a component of income tax expense.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted-average shares of common stock outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average shares of common stock and potentially dilutive securities outstanding for the period determined using the treasury-stock and if-converted methods. Diluted net loss per share excludes the potential impact of the Company’s common stock subject to repurchase, common stock options, restricted stock units, contingently issuable employee stock purchase plan shares and common stock issuable upon conversion of convertible notes because their effect would be anti-dilutive due to the Company’s net loss. The following table sets for the computation of basic and diluted earnings per share for the years ended December 31, 2023, 2022 and 2021(in thousands, except share and per share data): Year Ended December 31, 2023 2022 2021 Numerator: Net loss, basic $ ( 163,415 ) $ ( 135,665 ) $ ( 83,988 ) Add: Change in fair value of Holdback Indemnification liability — ( 214 ) — Add: Change in fair value of Contingent Milestone liability — ( 700 ) — Net loss, diluted $ ( 163,415 ) $ ( 136,579 ) $ ( 83,988 ) Denominator: Weighted-average shares of common stock outstanding, basic 40,885,124 33,839,072 30,321,722 Effect of dilutive securities: Weighted-average Holdback-Indemnification shares issuable — 19,590 — Weighted-average contingent milestone shares — 123,831 — Weighted-average shares of common stock outstanding, diluted 40,885,124 33,982,493 30,321,722 Net loss per share, basic $ ( 4.00 ) $ ( 4.01 ) $ ( 2.77 ) Net loss per share, diluted $ ( 4.00 ) $ ( 4.02 ) $ ( 2.77 ) The following outstanding potential dilutive shares have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect: As of December 31, 2023 2022 2021 Options to purchase common stock and restricted stock units 10,909,831 8,955,557 6,940,556 Common stock issuable upon conversion of convertible notes 9,964,247 — — Employee stock purchase plan contingently issuable 23,054 26,305 23,116 Common stock subject to repurchase — — 122,464 Total 20,897,132 8,981,862 7,086,136
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements On January 1, 2023, the Company adopted Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 requires an entity to utilize a new impairment model that requires measurement and recognition of expected credit losses for most financial assets and certain other instruments, including but not limited to available-for-sale debt securities. Credit losses relating to available-for-sale debt securities will be recorded through an allowance for credit losses rather than as a direct write-down to the security. The new guidance also modifies the impairment models for purchased financial assets with credit deterioration since their origination. There was no impact on the accompanying consolidated financial statements as of the adoption date. In March 2020, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2020-3, Codification Improvements to Financial Instruments which makes narrow-scope improvements to various financial instruments topics, including the new credit losses standard and clarifies the following areas (i) the contractual term of a net investment in a lease should be the contractual term used to measure expected credit losses; (ii) when an entity regains control of financial assets sold, an allowance for credit losses should be recorded. The Company adopted this standard on January 1, 2023 . There was no impact on the accompanying consolidated financial statements as of the adoption date.
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. 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 the accompanying consolidated financial statements and disclosures. In November 2023, the FASB issued ASU No. 2023-07, Improvements to Reportable Segment Disclosures (“ASU 2023-07”). This new guidance is designed to improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 on a retrospective basis. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting standard will have on its consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures (“ASU 2023-09”). This new guidance is designed to enhance the transparency and decision usefulness of income tax disclosures. The amendments of this update are related to the rate reconciliation and income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting standard will have on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash Reported Within the Consolidated Balance Sheets	The following table provides a reconciliation of cash, cash equivalents and restricted cash equivalents reported within the consolidated balance sheets that together reflect the same amounts shown in the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 286,326 $ 28,003 Restricted cash equivalents — 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 286,326 $ 128,003
Schedule Of Finite Lived Intangible Assets	The components of the Company’s intangible assets were as follows (in thousands, except for weighted-average remaining amortization period): December 31, 2023 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 39,000 $ ( 3,318 ) $ 35,682 16.2 Developed technology 226,620 ( 10,239 ) 216,381 11.7 Assembled workforce 970 ( 108 ) 862 2.7 Total intangible assets $ 266,590 $ ( 13,665 ) $ 252,925 12.3 December 31, 2022 Gross Carrying Value Accumulated Amortization Net Carrying Amount Weighted-Average Remaining Amortization Period Commercial milestones $ 34,000 $ ( 1,333 ) $ 32,667 17.1 Developed technology 28,107 ( 1,820 ) 26,287 8.4 Total intangible assets $ 62,107 $ ( 3,153 ) $ 58,954 11.9
Schedule of Estimated Future Amortization Expense Associated with Intangible Assets	The following table summarizes the estimated future amortization expense associated with the Company’s intangible assets as of December 31, 2023 (in thousands): Amount 2024 $ 21,545 2025 21,545 2026 21,436 2027 21,221 2028 21,221 Thereafter 145,957 $ 252,925
Schedule of Total Revenues and Disaggregates Product Sales	The following table presents Total revenues and disaggregates Product sales, net by approved medicine (in thousands): Year Ended December 31, 2023 2022 2021 Product sales, net: Livmarli $ 141,795 $ 75,062 $ 3,138 Bile Acid Medicines 37,079 — — Total product sales, net 178,874 75,062 3,138 License revenue 7,500 2,000 16,000 Total revenues $ 186,374 $ 77,062 $ 19,138
Schedule of Product Sales, Net by Geographic Area	The following table sets forth Product sales, net by geographic area based on the ship-to location (in thousands): Year Ended December 31, 2023 2022 2021 United States $ 146,699 $ 67,920 $ 2,913 Rest of world 32,175 7,142 225 Total product sales, net $ 178,874 $ 75,062 $ 3,138
Schedule of Computation of Basic and Diluted Earnings per Share	The following table sets for the computation of basic and diluted earnings per share for the years ended December 31, 2023, 2022 and 2021(in thousands, except share and per share data): Year Ended December 31, 2023 2022 2021 Numerator: Net loss, basic $ ( 163,415 ) $ ( 135,665 ) $ ( 83,988 ) Add: Change in fair value of Holdback Indemnification liability — ( 214 ) — Add: Change in fair value of Contingent Milestone liability — ( 700 ) — Net loss, diluted $ ( 163,415 ) $ ( 136,579 ) $ ( 83,988 ) Denominator: Weighted-average shares of common stock outstanding, basic 40,885,124 33,839,072 30,321,722 Effect of dilutive securities: Weighted-average Holdback-Indemnification shares issuable — 19,590 — Weighted-average contingent milestone shares — 123,831 — Weighted-average shares of common stock outstanding, diluted 40,885,124 33,982,493 30,321,722 Net loss per share, basic $ ( 4.00 ) $ ( 4.01 ) $ ( 2.77 ) Net loss per share, diluted $ ( 4.00 ) $ ( 4.02 ) $ ( 2.77 )
Summary of Outstanding Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share	The following outstanding potential dilutive shares have been excluded from the calculation of diluted net loss per share for the periods presented due to their anti-dilutive effect: As of December 31, 2023 2022 2021 Options to purchase common stock and restricted stock units 10,909,831 8,955,557 6,940,556 Common stock issuable upon conversion of convertible notes 9,964,247 — — Employee stock purchase plan contingently issuable 23,054 26,305 23,116 Common stock subject to repurchase — — 122,464 Total 20,897,132 8,981,862 7,086,136

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities to Fair Value Measurements On Recurring Basis and Level of Input Measurements	Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type are presented in the following table (in thousands): December 31, 2023 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 278,116 $ — $ — $ 278,116 Total financial assets $ 278,116 $ — $ — $ 278,116 December 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 124,227 $ — $ — $ 124,227 U.S. treasury bills 4,975 — — 4,975 Commercial paper — 74,386 — 74,386 U.S. government bonds — 44,354 — 44,354 Total financial assets $ 129,202 $ 118,740 $ — $ 247,942 Financial liabilities: Contingent milestone liability $ 3,900 $ — $ — $ 3,900 Derivative liability — — 1,090 1,090 Indemnification holdback — — 617 617 Total financial liabilities $ 3,900 $ — $ 1,707 $ 5,607
Summary of Changes in Fair Value classified as Level 3	The following table provides a summary of the changes in the estimated fair value of the Indemnification Holdback and Contingent Milestone liability within Level 3 of the fair value hierarchy (in thousands): Indemnification Holdback Liability Contingent Milestone Liability Balance at January 1, 2022 $ — $ — Initial recognition 831 4,600 Change in fair value ( 214 ) ( 700 ) Transfer out of Level 3 fair value hierarchy — ( 3,900 ) Balance at December 31, 2022 617 — Change in fair value 279 — Settlement of Indemnification Holdback liability ( 896 ) — Balance at December 31, 2023 $ — $ —

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Fair Value and Amortized Cost of Cash Equivalents and Available-for-sale Investments by Major Security Type	The fair value and amortized cost of cash equivalents and available-for-sale investments by major security type are presented in the following table (in thousands): December 31, 2023 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 278,116 $ — $ — $ 278,116 Total cash equivalents and investments $ 278,116 $ — $ — $ 278,116 Classified as: Cash equivalents $ 278,116 Total cash equivalents and investments $ 278,116 December 31, 2022 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market funds $ 124,227 $ — $ — $ 124,227 U.S. treasury bills 4,980 — ( 5 ) 4,975 Commercial paper 74,386 — — 74,386 U.S. government bonds 44,579 — ( 225 ) 44,354 Total cash equivalents and investments $ 248,172 $ — $ ( 230 ) $ 247,942 Classified as: Cash equivalents $ 24,226 Cash equivalents - restricted 100,000 Short-term investments 123,716 Total cash equivalents, restricted cash equivalents and investments $ 247,942

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2023
Balance Sheet Components [Abstract]
Schedule of Inventory	Inventory consists of the following (in thousands): December 31, 2023 2022 Raw materials $ 2,998 $ — Work in progress 9,873 5,351 Finished goods 9,441 214 Total inventory $ 22,312 $ 5,565
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, 2023 2022 Accrued compensation and related benefits $ 20,939 $ 14,660 Accrued sales deductions 23,650 4,284 Accrued clinical trials 7,268 8,319 Accrued professional service fees 7,941 5,372 Accrued manufacturing and non-clinical costs 9,922 3,927 Accrued royalties payable 6,716 2,456 Accrued interest 2,108 — Accrued milestone payments — 15,000 Total accrued expenses $ 78,544 $ 54,018

Revenue Interest Purchase Agr_2

Revenue Interest Purchase Agreement (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Revenue Interest Liability	The following table summarizes the revenue interest liability activity during the years ended December 31, 2023 and 2022 (in thousands): Revenue Interest Liability Derivative Liability Balance at January 1, 2022 $ 129,923 $ 1,996 Interest expense recognized 15,979 — Revenue interest payments ( 5,551 ) — Change in fair value — ( 906 ) Revenue interest liability at December 31, 2022 140,351 1,090 Interest expense recognized 5,060 — Revenue interest payments ( 2,883 ) — Revenue interest liability settlement ( 192,694 ) — Loss (gain) from termination of revenue interest purchase agreement 50,166 ( 1,090 ) Revenue interest liability at December 31, 2023 $ — $ —

Asset Acquisitions (Tables)

Asset Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2023
Bile Acid Medicines
Asset Acquisitions [Line Items]
Schedule of Consideration Paid and Allocation of Costs	The following represents the consideration paid and allocation of the purchase price for the acquisition of the Bile Acid Medicines (in thousands): Cash consideration $ 210,378 Transaction costs 2,384 Total purchase consideration 212,762 Assets acquired: Inventory 12,900 Intangible assets - developed technology 198,513 Intangible assets - assembled workforce 970 Other current and noncurrent assets 379 Total assets acquired $ 212,762
Satiogen
Asset Acquisitions [Line Items]
Schedule of Consideration Paid and Allocation of Costs	The following represents the consideration paid and allocation of purchase price for the acquisition of Satiogen (in thousands, except per share data): Issued common stock $ 15,585 Cash consideration 2,600 Indemnification Holdback 831 Contingent consideration settled in common stock 4,600 Transaction costs 545 Total purchase consideration 24,161 Assets acquired: Intangible assets - developed technology 21,561 Cash consideration 2,600 Total assets acquired $ 24,161

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Undiscounted Future Minimum Payments under Operating Leases	As of December 31, 2023, undiscounted future minimum payments under the Company’s operating leases are as follows (in thousands): Years Ended December 31, Undiscounted 2024 $ 1,193 2025 366 2026 123 2027 123 2028 61 Total undiscounted lease payments 1,866 Less: imputed interest ( 145 ) Total lease liability $ 1,721

Convertible Notes (Tables)

Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule Of Convertible Notes	As of December 31, 2023, the Notes consisted of the following (in thousands): Convertible Notes Principal amount $ 316,250 Unamortized debt discount and issuance costs ( 9,829 ) Net carrying amount $ 306,421
Schedule of Interest Expense Related to Convertible Notes	The following table sets forth interest expense recognized related to the Notes (in thousands): Year Ended 2023 Coupon interest expense $ 8,925 Amortization of debt discount and issuance costs 1,120 Total interest expense on convertible notes $ 10,045

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	Common stock reserved for issuance is as follows: December 31, 2023 2022 Stock options, restricted stock units and performance stock units issued and outstanding 10,909,831 8,955,557 Reserved for future stock awards or option grants 2,230,264 1,596,947 Reserved for employee stock purchase plan 1,040,828 1,157,570 Common stock issuable upon conversion of convertible notes 9,964,247 — Common stock held back in connection with asset acquisition — 31,638 Common stock issuable as contingent consideration in connection with asset acquisition — 199,993 24,145,170 11,941,705

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity during the year ended December 31, 2023 (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2022 8,340,083 $ 13.63 7.5 $ 51,645 Granted 2,066,089 $ 25.35 Exercised ( 514,443 ) $ 16.09 Canceled and forfeited ( 259,225 ) $ 18.80 Outstanding as of December 31, 2023 9,632,504 $ 15.87 6.9 $ 131,785 Vested and exercisable as of December 31, 2023 5,978,571 $ 12.12 5.9 $ 104,048
Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards Granted	The following assumptions were used to estimate the fair value of stock option awards granted during the following periods: Year ended December 31, 2023 2022 2021 Expected term (in years) 5.3 - 6.1 5.5 - 6.1 5.5 - 6.1 Expected volatility 80.17 %- 85.24 % 80.86 %- 83.20 % 82.76 %- 94.06 % Risk-free interest rate 3.35 %- 4.67 % 1.46 %- 4.10 % 0.62 %- 1.34 % Expected dividend yield — — —
Summary of RSU Activity	The following table summarizes the activity under the Company’s restricted stock units for the year ended December 31, 2023: Number of Weighted-Average Grant Date Fair Value per Award Unvested and outstanding as of December 31, 2022 615,474 $ 18.36 Granted 824,584 $ 25.48 Vested ( 245,783 ) $ 18.36 Cancelled/Forfeited ( 64,783 ) $ 20.82 Unvested and Outstanding as of December 31, 2023 1,129,492 $ 23.41
Summary of Stock-based Compensation Reflected in Consolidated Statements of Operations	Total stock-based compensation is reflected in the accompanying consolidated statements of operations as follows (in thousands): Year Ended December 31, 2023 2022 2021 Selling, general and administrative $ 24,131 $ 16,957 $ 13,128 Research and development 10,892 10,050 9,888 Total $ 35,023 $ 27,007 $ 23,016 Stock-based compensation reflected in cost of goods sold for the years ended December 31, 2023, 2022 and 2021 was insignificant.
Share-Based Payment Arrangement, Performance Shares, Activity [Table Text Block]	The following table summarizes the activity under the Company's performance stock units for the year ended December 31, 2023: Number of Weighted-Average Grant Date Unvested and outstanding as of December 31, 2022 — $ — Granted 147,835 $ 23.64 Unvested and outstanding as of December 31, 2023 147,835 $ 23.64

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Losses before Provision for Income Taxes	The Company’s losses before provision for income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 2021 U.S. loss before taxes $ ( 164,953 ) $ ( 142,661 ) $ ( 84,217 ) Foreign income before taxes 2,529 590 266 Loss before income taxes $ ( 162,424 ) $ ( 142,071 ) $ ( 83,951 )
Schedule of Components of Income Tax (Expense) Benefit	The income tax (expense) benefit applicable to income before income taxes consists of the following: Year Ended December 31, 2023 2022 2021 Current income taxes: Federal $ 37 $ — $ — State 67 18 — Foreign 887 157 37 Total current 991 175 37 Deferred taxes: Federal — ( 5,503 ) — State — ( 1,078 ) — Total deferred — ( 6,581 ) — Income tax (benefit) expense $ 991 $ ( 6,406 ) $ 37
Summary of Reconciliation of Federal Statutory Income Tax Rate	A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2023 2022 2021 Federal statutory income tax rate 21.00 % 21.00 % 21.00 % State tax 3.57 7.40 1.32 Permanent differences ( 0.50 ) ( 0.65 ) ( 1.70 ) Other ( 0.13 ) ( 0.93 ) 0.02 Executive compensation — ( 2.99 ) — Global intangible low-taxed income ( 1.69 ) ( 1.43 ) — Tax credits 1.91 4.96 7.72 Change in valuation allowance ( 24.77 ) ( 22.85 ) ( 28.41 ) Total tax benefit ( 0.61 ) % 4.51 % ( 0.05 ) %
Significant Components of Deferred Taxes	The significant components of the Company’s deferred taxes are as follows (in thousands): December 31, 2023 2022 Deferred tax assets: Net operating losses $ 40,455 $ 34,522 Capitalized research and development 38,065 23,569 Tax credit carryforwards 30,071 26,747 Interest limitation attributes 15,814 3,127 Stock-based compensation 8,419 6,726 Intangibles 4,055 4,733 Accrued expenses 3,953 3,101 Inventory 2,316 426 Lease liability 269 460 Total deferred tax assets 143,417 103,411 Deferred tax liabilities: Operating lease right-of-use assets ( 161 ) ( 272 ) Fixed assets ( 37 ) ( 100 ) Total deferred tax liabilities ( 198 ) ( 372 ) Valuation allowance ( 143,219 ) ( 103,039 ) Net deferred tax assets $ — $ —
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2023 2022 Balance at beginning of year $ 9,254 $ 6,399 (Decrease) related to prior year tax positions — — Increases related to current year tax positions 1,200 2,855 Balance at end of year $ 10,454 $ 9,254

Organization and Description _2

Organization and Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2023 USD ($) $ / shares shares	Apr. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Segment $ / shares shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Date of incorporation			May 02, 2018
Number of operating segment | Segment			1
Accumulated deficit			$ (556,239)	$ (392,824)
Cash and cash equivalents			286,326	28,003
Unrestricted cash and cash equivalents			286,300
Proceeds from issuance of common stock in at-the-market offerings, net of issuance costs		$ 305,300	14,480	21,289	$ 0
Proceeds to repurchase future revenue interests		192,700
Restricted cash equivalents		$ 100,000	0	$ 100,000
Bile Acid Portfolio Acquisition
Upfront payment			210,400
Milestone payment			$ 235,000
Shares issued, price per share | $ / shares	$ 26.25		$ 26.25
Net proceeds from transaction	$ 202,200		$ 202,200
Bile Acid Portfolio Acquisition | Private Placement
Issuance of common stock, Shares | shares	8,000,000		8,000,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Customer	Dec. 31, 2022 USD ($) Customer	Dec. 31, 2021 USD ($) Customer	Apr. 30, 2023 USD ($)	Jan. 01, 2023	Jan. 22, 2019
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents	$ 0	$ 100,000,000		$ 100,000,000
Allowance for credit losses	0
Accounts Receivable, Credit Loss Expense (Reversal)	0	0	$ 0
Amount on purchase commitments	5,200,000
Fair value of its investments related to credit loss	$ 0
Investments with original maturities at date of purchase to be cash equivalents	3 months
Property and equipment, net	$ 706,000	914,000
Accumulated depreciation	1,500,000	1,000,000
Depreciation Expense	300,000	300,000	300,000
Impairment of long-lived assets	0
Amortization expense	$ 10,500,000	2,900,000	300,000
Term of lease	12 months					4 years
Advertising Expense	$ 6,300,000	4,000,000	9,200,000
Unrealized foreign exchange loss	(1,764,000)	0	$ 0
Other Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Amount on purchase commitments	3,800,000
Accounting Standards Update 2018-18
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, immaterial effect [true false]					true
Change in accounting principle, accounting standards update, adopted [true false]					true
Change in accounting principle, accounting standards update, adoption date					Jan. 01, 2023
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, net	1,300,000	1,300,000
Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, net	$ 900,000	$ 600,000
Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of customer | Customer	0	1
Revenue from Contract with Customer Benchmark [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of customer | Customer	1	1	1
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Minimum | Accounts Receivable | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	10%
Minimum | Revenue from Contract with Customer Benchmark [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage	10%	10%	10%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years
Maximum | Accounts Receivable | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk percentage		23%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash Reported Within the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Apr. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 286,326		$ 28,003
Restricted cash equivalents	0	$ 100,000	100,000
Total cash, cash equivalents, and restricted cash equivalents	$ 286,326		$ 128,003	$ 131,340	$ 142,086

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule Of Finite Lived Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Aug. 31, 2023	Dec. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Gross Carrying Value	$ 266,590		$ 62,107
Accumulated Amortization	(13,665)		(3,153)
Net Carrying Value	$ 252,925		$ 58,954
Weighted-Average Remaining Amortization Period (Years)	12 years 3 months 18 days		11 years 10 months 24 days
Commercial milestones
Summary Of Significant Accounting Policies [Line Items]
Gross Carrying Value	$ 39,000		$ 34,000
Accumulated Amortization	(3,318)		(1,333)
Net Carrying Value	$ 35,682		$ 32,667
Weighted-Average Remaining Amortization Period (Years)	16 years 2 months 12 days		17 years 1 month 6 days
Developed technology
Summary Of Significant Accounting Policies [Line Items]
Gross Carrying Value	$ 226,620		$ 28,107
Accumulated Amortization	(10,239)		(1,820)
Net Carrying Value	$ 216,381		$ 26,287
Weighted-Average Remaining Amortization Period (Years)	11 years 8 months 12 days	12 years 6 months	8 years 4 months 24 days
Assembled workforce
Summary Of Significant Accounting Policies [Line Items]
Gross Carrying Value	$ 970
Accumulated Amortization	(108)
Net Carrying Value	$ 862
Weighted-Average Remaining Amortization Period (Years)	2 years 8 months 12 days	3 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Schedule of Estimated Future Amortization Expense Associated with Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
2024	$ 21,545
2025	21,545
2026	21,436
2027	21,221
2028	21,221
Thereafter	145,957
Net Carrying Value	$ 252,925	$ 58,954

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Schedule of Total Revenues and Disaggregates Product Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 186,374	$ 77,062	$ 19,138
Livmarli
Summary Of Significant Accounting Policies [Line Items]
Revenue	141,795	75,062	3,138
Bile Acid Medicines
Summary Of Significant Accounting Policies [Line Items]
Revenue	37,079	0	0
Product
Summary Of Significant Accounting Policies [Line Items]
Revenue	178,874	75,062	3,138
License revenue
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 7,500	$ 2,000	$ 16,000

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Schedule of Product Sales, Net by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 186,374	$ 77,062	$ 19,138
Product
Summary Of Significant Accounting Policies [Line Items]
Revenue	178,874	75,062	3,138
Product | United States
Summary Of Significant Accounting Policies [Line Items]
Revenue	146,699	67,920	2,913
Product | Rest of World
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 32,175	$ 7,142	$ 225

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Schedule of Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss, basic	$ (163,415)	$ (135,665)	$ (83,988)
Add: Change in fair value of Holdback Indemnification liability	0	(214)	0
Add: Change in fair value of Contingent Milestone liability	0	(700)	0
Net loss, diluted	$ (163,415)	$ (136,579)	$ (83,988)
Denominator:
Weighted-average shares of common stock outstanding, basic	40,885,124	33,839,072	30,321,722
Effect of dilutive securities:
Weighted Average Holdback Indemnification Shares Issuable	0	19,590	0
Weighted Average Contingent Milestone Shares	0	123,831	0
Weighted-average shares of common stock outstanding, diluted	40,885,124	33,982,493	30,321,722
Earnings Per Share, Basic	$ (4)	$ (4.01)	$ (2.77)
Earnings Per Share, Diluted	$ (4)	$ (4.02)	$ (2.77)

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share (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]
Anti-dilutive shares of stock	20,897,132	8,981,862	7,086,136
Common stock issuable upon conversion of convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	9,964,247	0	0
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	10,909,831	8,955,557	6,940,556
Employee Stock Purchase Plan (ESPP)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	23,054	26,305	23,116
Common Stock Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	0	0	122,464

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities to Fair Value Measurement On Recurring Basis and Level of Input Measurement (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financial liabilities:
Derivative liability	$ 0	$ 1,090	$ 1,996
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Derivative Liability, Current
Fair Value, Recurring Basis
Financial assets:
Fair value measurements	278,116	$ 247,942
Financial liabilities:
Derivative liability		1,090
Total financial liabilities		5,607
Fair Value, Recurring Basis | Indemnification Holdback Liability
Financial liabilities:
Total financial liabilities		617
Fair Value, Recurring Basis | Contingent Milestone Liability
Financial liabilities:
Total financial liabilities		3,900
Fair Value, Recurring Basis | Level 1
Financial assets:
Fair value measurements	278,116	129,202
Financial liabilities:
Derivative liability		0
Total financial liabilities		3,900
Fair Value, Recurring Basis | Level 1 | Indemnification Holdback Liability
Financial liabilities:
Total financial liabilities		0
Fair Value, Recurring Basis | Level 1 | Contingent Milestone Liability
Financial liabilities:
Total financial liabilities		3,900
Fair Value, Recurring Basis | Level 2
Financial assets:
Fair value measurements	0	118,740
Financial liabilities:
Derivative liability		0
Total financial liabilities		0
Fair Value, Recurring Basis | Level 2 | Indemnification Holdback Liability
Financial liabilities:
Total financial liabilities		0
Fair Value, Recurring Basis | Level 2 | Contingent Milestone Liability
Financial liabilities:
Total financial liabilities		0
Fair Value, Recurring Basis | Level 3
Financial assets:
Fair value measurements	0	0
Financial liabilities:
Derivative liability		1,090
Total financial liabilities		1,707
Fair Value, Recurring Basis | Level 3 | Indemnification Holdback Liability
Financial liabilities:
Total financial liabilities		617
Fair Value, Recurring Basis | Level 3 | Contingent Milestone Liability
Financial liabilities:
Total financial liabilities		0
Fair Value, Recurring Basis | Money Market Fund
Financial assets:
Fair value measurements	278,116	124,227
Fair Value, Recurring Basis | Money Market Fund | Level 1
Financial assets:
Fair value measurements	278,116	124,227
Fair Value, Recurring Basis | Money Market Fund | Level 2
Financial assets:
Fair value measurements	0	0
Fair Value, Recurring Basis | Money Market Fund | Level 3
Financial assets:
Fair value measurements	$ 0	0
Fair Value, Recurring Basis | U.S. treasury bills
Financial assets:
Fair value measurements		4,975
Fair Value, Recurring Basis | U.S. treasury bills | Level 1
Financial assets:
Fair value measurements		4,975
Fair Value, Recurring Basis | U.S. treasury bills | Level 2
Financial assets:
Fair value measurements		0
Fair Value, Recurring Basis | U.S. treasury bills | Level 3
Financial liabilities:
Total financial liabilities		0
Fair Value, Recurring Basis | Commercial Paper
Financial assets:
Fair value measurements		74,386
Fair Value, Recurring Basis | Commercial Paper | Level 1
Financial assets:
Fair value measurements		0
Fair Value, Recurring Basis | Commercial Paper | Level 2
Financial assets:
Fair value measurements		74,386
Fair Value, Recurring Basis | Commercial Paper | Level 3
Financial assets:
Fair value measurements		0
Fair Value, Recurring Basis | U.S. Government Bonds
Financial assets:
Fair value measurements		44,354
Fair Value, Recurring Basis | U.S. Government Bonds | Level 1
Financial assets:
Fair value measurements		0
Fair Value, Recurring Basis | U.S. Government Bonds | Level 2
Financial assets:
Fair value measurements		44,354
Fair Value, Recurring Basis | U.S. Government Bonds | Level 3
Financial assets:
Fair value measurements		$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	1 Months Ended	6 Months Ended
	Jun. 30, 2023 shares	Jun. 30, 2023 shares	Dec. 31, 2023 USD ($) shares	Jan. 31, 2023 shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Common stock, shares, issued			46,723,143		36,956,345
Issuance of common stock in connection with settlement of Indemnification Holdback liability, Shares		31,631
Common Stock [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Issuance of common stock in connection with settlement of Indemnification Holdback liability, Shares	31,631
Contingent Milestone Liability
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Common stock, shares, issued				199,993
Indemnification Holdback liability | $			$ 0		$ 0	$ 0
Indemnification Holdback Liability [Member] | Contingent Milestone Liability
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Indemnification Holdback liability | $			$ 0
Discount Rate
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Discount rate used for valuation to derivative liability			0.157

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Changes in Fair Value classified as Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Indemnification Holdback Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 617	$ 0
Initial recognition		831
Change in fair value	279	(214)
Transfer out of Level 3 fair value hierarchy		0
Settlement of Indemnification Holdback liability	(896)
Ending Balance	0	617
Contingent Milestone Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	0
Initial recognition		4,600
Change in fair value	0	(700)
Transfer out of Level 3 fair value hierarchy		(3,900)
Settlement of Indemnification Holdback liability	0
Ending Balance	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Fair Value and Amortized Cost of Cash Equivalents and Available-for-sale Investments by Major Security Type (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Cash equivalents and investments, Amortized cost	$ 278,116	$ 248,172
Total Cash equivalents and investments, Unrealized gain	0	0
Total Cash equivalents and investments, Unrealized loss	0	(230)
Cash equivalents and investments, Estimated Fair Value	278,116	247,942
Cash equivalents, Estimated Fair Value	278,116	24,226
Cash equivalents - Restricted, Estimated Fair Value		100,000
Short-term investments		123,716
Total cash equivalents and investments	278,116	247,942
Money Market Fund
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	278,116	124,227
Cash equivalents, Estimated Fair Value	$ 278,116	124,227
U.S. treasury bills
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost		4,980
Investments, Unrealized Gain		0
Investments, Unrealized Loss		(5)
Investments, Estimated Fair Value		4,975
Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost		74,386
Investments, Unrealized Gain		0
Investments, Unrealized Loss		0
Investments, Estimated Fair Value		74,386
U.S. Government Bonds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost		44,579
Investments, Unrealized Gain		0
Investments, Unrealized Loss		(225)
Investments, Estimated Fair Value		$ 44,354

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Financial Instruments, Owned, at Fair Value, by Type, Alternative [Abstract]
Realized gains or losses on available-for-sale investments	$ 0	$ 0
Investments in continuous unrealized loss position for more than 12 months	0	0
Credit losses on debt securities	$ 0	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Raw materials	$ 2,998	$ 0
Work in progress	9,873	5,351
Finished goods	9,441	214
Total Inventory	$ 22,312	$ 5,565

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued compensation and related benefits	$ 20,939	$ 14,660
Accrued sales deductions	23,650	4,284
Accrued clinical trials	7,268	8,319
Accrued professional service fees	7,941	5,372
Accrued manufacturing and non-clinical costs	9,922	3,927
Accrued royalties payable	6,716	2,456
Accrued interest	2,108	0
Accrued milestone payments	0	15,000
Total accrued expenses	$ 78,544	$ 54,018

Revenue Interest Purchase Agr_3

Revenue Interest Purchase Agreement - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Apr. 30, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue interest liability		$ 0	$ 140,351,000
Derivative liability		0	1,090,000
Loss from termination of revenue interest purchase agreement		$ (49,076,000)	0	$ 0
Revenue Interest Purchase Agreement | Mulholland SA LLC,
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of revenue interest payments on annual net sales at Tier 1		9.75%
Percentage of revenue interest payments on annual net sales at Tier 2 and Tier 3		2%
Required repurchase price percentage of cumulative purchaser prior to first anniversary of closing date		120%
Required revenue interest payment percentage to cumulative purchaser payments to reduce interest rate		175%
Required repurchase price percentage of cumulative purchaser payments after first anniversary and prior to third anniversary of closing date		175%
Required repurchase price percentage of cumulative purchaser after third anniversary of closing date		195%
Purchase agreement amount allocated to debt		$ 49,200,000
Initial fair value of derivative liability		1,300,000
Debt issuance costs		900,000
Interest expense		5,100,000	$ 16,000,000	$ 17,600,000
Payment on repurchase in connection with RIPA						$ 192,700,000
Loss from termination of revenue interest purchase agreement		49,100,000
Loss related to settlement of revenue interest liability		50,200,000
Gain on derecognition of related derivative liability		1,100,000
Revenue Interest Purchase Agreement | Mulholland SA LLC, | Maximum | On or Prior to December 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payment to be received at the option of purchasers		50,000,000
Revenue Interest Purchase Agreement | Mulholland SA LLC, | Commercialization and Development of Product and Other Working Capital Needs
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received		50,000,000
Revenue Interest Purchase Agreement | Mulholland SA LLC, | Livmarli
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone and upfront payments received		115,000,000
Upfront payment received					$ 50,000,000
Milestone payment received	$ 65,000,000
Potential milestone payment received upon regulatory approval		35,000,000
Tier I | Mulholland SA LLC, | Livmarli | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		350,000,000
Tier 2 | Mulholland SA LLC, | Livmarli | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		350,000,000
Tier 2 | Mulholland SA LLC, | Livmarli | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		1,100,000,000
Tier 3 | Mulholland SA LLC, | Livmarli | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		$ 1,100,000,000
CSPA | Mulholland SA LLC,
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares sold		509,164
Aggregate purchase price		$ 10,000,000
Net proceeds from transaction		10,000,000
Purchase agreement amount allocated to common stock issued		$ 10,800,000

Revenue Interest Purchase Agr_4

Revenue Interest Purchase Agreement - Summary of Revenue Interest Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest Expense, Interest-Bearing Liability [Abstract]
Revenue interest liability	$ 140,351	$ 129,923
Interest expense recognized	5,060	15,979
Revenue interest payments	(2,883)	(5,551)
Change in fair value		0
Revenue interest liability settlement	(192,694)
Loss (gain) from termination of revenue interest purchase agreement	50,166
Revenue interest liability	0	140,351	$ 129,923
Derivative Liability [Abstract]
Derivative liability	1,090	1,996
Interest expense recognized	0	0
Revenue interest payments	0	0
Change in fair value	0	(906)	732
Revenue interest liability settlement	0
Loss (gain) from termination of revenue interest purchase agreement	(1,090)
Derivative liability	$ 0	$ 1,090	$ 1,996

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details)		1 Months Ended				6 Months Ended	12 Months Ended
	Aug. 31, 2023 USD ($)	Aug. 31, 2023 USD ($)	Jan. 31, 2023 shares	May 31, 2022 USD ($) shares	Nov. 30, 2018 USD ($) ProductCandidate	Jun. 30, 2023 shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 13, 2024 USD ($)	Sep. 30, 2023 USD ($)
Asset Acquisitions [Line Items]
Issuance of common stock in connection with settlement of Indemnification Holdback liability, Shares | shares						31,631
Intangible asset useful lives							12 years 3 months 18 days	11 years 10 months 24 days
Developed technology
Asset Acquisitions [Line Items]
Intangible asset useful lives	12 years 6 months	12 years 6 months					11 years 8 months 12 days	8 years 4 months 24 days
Assembled workforce
Asset Acquisitions [Line Items]
Intangible asset useful lives	3 years	3 years					2 years 8 months 12 days
Satiogen
Asset Acquisitions [Line Items]
Total purchase consideration				$ 24,161,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares				609,305
Business Acquisition, Equity Interest Issued or Issuable, Number of Additional Shares | shares				32,494
Stock option exercise price				$ 200,000
Business Acquisition Future Issuance Of Additional Shares | shares			199,993	199,993
Cash Consideration				$ 2,600,000
Bile Acid Medicines
Asset Acquisitions [Line Items]
Total purchase consideration		$ 212,762,000
Cash Consideration		210,378,000
Livmarli
Asset Acquisitions [Line Items]
Milestones accrued									$ 10,000,000
Shire | Livmarli
Asset Acquisitions [Line Items]
Development or Regulatory Milestones Incurred							$ 0	$ 0
Shire Agreement | Livmarli
Asset Acquisitions [Line Items]
Milestones accrued								$ 15,000,000
License agreement milestone amount accrued										$ 5,000,000
Shire Agreement | Shire
Asset Acquisitions [Line Items]
Number of product candidates | ProductCandidate					2
Product sales milestone payments, payable					$ 30,000,000
Shire Agreement | Shire | Volixibat
Asset Acquisitions [Line Items]
Milestone payments, payable upon commercialization					30,000,000
Shire Agreement | Shire | Livmarli
Asset Acquisitions [Line Items]
Milestone payments, payable					109,500,000
Milestone payments, payable upon approval					25,000,000
Assigned License Agreement | Satiogen Pharmaceuticals, Inc.
Asset Acquisitions [Line Items]
Milestone payments, payable					10,500,000
Milestone payments, payable upon approval					5,000,000
Milestone payments, payable upon initiation					500,000
Milestone payments, payable upon commercialization					5,000,000
Assigned License Agreement | Sanofi-Aventis Deutschland GmbH
Asset Acquisitions [Line Items]
Milestone payments, payable					$ 36,000,000
Royalty obligations payment period					10 years
Milestones accrued							$ 0
Asset Purchase Agreement | Travere Therapeutics, Inc. | Bile Acid Medicines
Asset Acquisitions [Line Items]
Product sales milestone payments, payable	$ 235,000,000	$ 235,000,000
Cash Consideration	$ 210,400,000

Asset Acquisitions - Schedule o

Asset Acquisitions - Schedule of Consideration Paid and Allocation of Costs (Details) - USD ($) $ in Thousands	1 Months Ended
	Aug. 31, 2023	May 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Indemnification Holdback			$ 3,849	$ 4,532
Satiogen
Business Acquisition [Line Items]
Issued common stock		$ 15,585
Cash consideration		2,600
Indemnification Holdback		831
Contingent consideration settled in common stock		4,600
Transaction costs		545
Total purchase consideration		24,161
Assets acquired:
Cash Consideration		2,600
Total assets acquired		24,161
Satiogen | Developed technology
Assets acquired:
Intangible assets		$ 21,561
Bile Acid Medicines
Business Acquisition [Line Items]
Cash consideration	$ 210,378
Transaction costs	2,384
Total purchase consideration	212,762
Assets acquired:
Inventory	12,900
Cash Consideration	210,378
Other current and noncurrent assets	379
Total assets acquired	212,762
Bile Acid Medicines | Developed technology
Assets acquired:
Intangible assets	198,513
Bile Acid Medicines | Assembled workforce
Assets acquired:
Intangible assets	$ 970

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Detail) - Exclusive Licensing Agreement - Livmarli - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Jul. 31, 2021	Apr. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CANbridge
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received		$ 11
Research and development funding received			$ 2.3	$ 0.9	$ 1.9
Achievement of future regulatory and commercial milestones payment			2	$ 5
GC Pharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received	$ 5
Achievement of future regulatory and commercial milestones payment			$ 2.5
Maximum | CANbridge
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development funding received		5
Potential regulatory and commercial milestone payment to be received		$ 109
Maximum | GC Pharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Achievement of future regulatory and commercial milestones payment	$ 23

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands		1 Months Ended	12 Months Ended
	Jan. 17, 2024 USD ($) ft²	Nov. 30, 2019 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 31, 2019 USD ($)	Jan. 22, 2019 ft²
Lessee Lease Description [Line Items]
Area of office space | ft²							5,600
Term of lease			12 months				4 years
Operating lease, option to extend, description			The lease term is approximately four years with an option to extend the term for one five-year term, which at the time was not reasonably assured of exercise and therefore, not included in the lease term.
Existence of option to extend			true
Term of extension of lease						5 years
Tenant improvement allowance						$ 400
Operating lease right-of-use assets			$ 1,284	$ 1,431
Lease liability			$ 1,721
Weighted-average incremental borrowing rate			8%
Weighted-average remaining lease term			2 years 1 month 6 days
Rent expense			$ 800	800	$ 700
Variable lease payments			$ 200	$ 200
Subsequent Event
Lessee Lease Description [Line Items]
Area of office space | ft²	36,300
Term of lease	5 years
Rent expense	$ 10,800
Amended Operating Lease Agreement
Lessee Lease Description [Line Items]
Term of lease		5 years
Additional area of office space | ft²		5,555
Lease expiration, month and year		2025-03
Amended Operating Lease Agreement | Property, Plant and Equipment
Lessee Lease Description [Line Items]
Tenant improvement allowance		$ 800
Amended Operating Lease Agreement | Restatement Adjustment
Lessee Lease Description [Line Items]
Operating lease right-of-use assets		600
Lease liability		$ 600

Leases - Schedule of Undiscount

Leases - Schedule of Undiscounted Future Minimum Payments under Operating Leases (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Leases [Abstract]
2024	$ 1,193
2025	366
2026	123
2027	123
2028	61
Total undiscounted lease payments	1,866
Less: imputed interest	(145)
Total lease liability	$ 1,721

Convertible Notes - Additional

Convertible Notes - Additional Information (Detail) - Senior Notes Due At Two Thousand Twenty Nine [Member] $ / shares in Units, $ in Thousands	1 Months Ended				6 Months Ended
	Apr. 30, 2023 USD ($) $ / shares	Apr. 30, 2023 USD ($) $ / shares	Apr. 30, 2023 USD ($) Days $ / shares	Apr. 30, 2023 USD ($) Tradingday $ / shares	Jun. 30, 2023 Days	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Principle amount	$ 316,300	$ 316,300	$ 316,300	$ 316,300		$ 316,250
Consecutive trading day			30	10	30
Number of consecutive trading days before five business days during the measurement period | Tradingday				10
Trading days | Days			20		20
Net proceeds from debt issuance	$ 305,300
Interest rate (percent)	4%	4%	4%	4%
Consecutive trading days immediately after measurement period | Tradingday				5
Initial conversion price/rate | $ / shares	$ 31.5075	$ 31.5075	$ 31.5075	$ 31.5075
Debt instrument conversion ratio multiple of principal	$ 1,000
Common stock exceeds		130%			130%
Principal amount redeemable	$ 75,000	$ 75,000	$ 75,000	$ 75,000
Percentage of principal amount of notes declared as accrued based on certain customary events of default		25%
Debt instrument remaining life						5 years 3 months 18 days
Effective interest rate (as a percent)						4.60%
Convertible debt, fair value						$ 387,300
Debt issuance costs						$ 10,900
Common Stock
Debt Instrument [Line Items]
Initial conversion price/rate | $ / shares	$ 31.74	$ 31.74	$ 31.74	$ 31.74
Maximum
Debt Instrument [Line Items]
Conversion premium percentage on sale price of common stock					98%

Convertible Notes - Schedule Of

Convertible Notes - Schedule Of Convertible Notes (Details) - Senior Notes Due At Two Thousand Twenty Nine [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Apr. 30, 2023
Debt Instrument [Line Items]
Principle amount	$ 316,250	$ 316,300
Unamortized debt discount and issuance costs	(9,829)
Net carrying amount	$ 306,421

Convertible Notes - Schedule _2

Convertible Notes - Schedule of Interest Expense Related to Convertible Notes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 1,117	$ 0	$ 0
Senior Notes Due At Two Thousand Twenty Nine [Member]
Debt Instrument [Line Items]
Coupon interest expense	8,925
Amortization of debt discount and issuance costs	1,120
Total interest expense on convertible notes	$ 10,045

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended			12 Months Ended
	Dec. 31, 2023	Nov. 02, 2023	Aug. 31, 2023	Apr. 30, 2023	Aug. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 31, 2020
Class Of Stock [Line Items]
Proceeds from issuance of shares				$ 305,300		$ 14,480	$ 21,289	$ 0
Maximum amount of sale covered in shelf registration statement									$ 300,000
Bile Acid Portfolio Acquisition
Class Of Stock [Line Items]
Shares issued, price per share	$ 26.25		$ 26.25			$ 26.25
Net proceeds from transaction			$ 202,200			$ 202,200
Leerink Partners LLC
Class Of Stock [Line Items]
Maximum amount of offering issuance and sale covered in sales agreement									$ 75,000
Sales Agreement
Class Of Stock [Line Items]
Net proceeds from transaction		$ 200,000
Percentage of gross proceeds		3%
Common Stock | Sales Agreement
Class Of Stock [Line Items]
Number of shares issued	2,125,090				3,478,261	658,206
Shares issued, price per share					$ 23
Proceeds from issuance of shares						$ 14,500
Gross proceeds from issuance of common stock	$ 43,700					$ 15,000
Private Placement | Bile Acid Portfolio Acquisition
Class Of Stock [Line Items]
Number of shares issued			8,000,000			8,000,000
Private Placement | Common Stock
Class Of Stock [Line Items]
Number of shares issued						8,000,000
Underwritten Public Offerings | Common Stock | Sales Agreement | Maximum
Class Of Stock [Line Items]
Number of shares issued					521,739
Public Offering
Class Of Stock [Line Items]
Proceeds from issuance of shares					$ 86,100
Public Offering | Common Stock
Class Of Stock [Line Items]
Number of shares issued							4,000,000	375,654

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Common stock reserved for issuance	24,145,170	11,941,705
Common stock issuable upon conversion of convertible notes
Class Of Stock [Line Items]
Common stock reserved for issuance	9,964,247	0
Stock options, restricted stock units and performance stock units issued and outstanding
Class Of Stock [Line Items]
Common stock reserved for issuance	10,909,831	8,955,557
Reserved for Future Stock Awards or Option Grants
Class Of Stock [Line Items]
Common stock reserved for issuance	2,230,264	1,596,947
Reserved for Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,040,828	1,157,570
Common stock held back in connection with asset acquisition
Class Of Stock [Line Items]
Common stock reserved for issuance	0	31,638
Common stock issuable as contingent consideration in connection with asset acquisition
Class Of Stock [Line Items]
Common stock reserved for issuance	0	199,993

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Jun. 30, 2023	Jan. 31, 2023	Jul. 31, 2019	Nov. 30, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance					24,145,170	11,941,705
Stock-based compensation expense					$ 35,023	$ 27,007	$ 23,016
Share-based compensation expenses capitalized amount					800	400	100
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, Intrinsic value of options exercised					5,700	$ 3,000	$ 1,300
Total unrecognized stock-based compensation related to unvested stock option awards granted					$ 48,500
Unrecognized stock-based compensation related to unvested stock, expected to recognize over weighted-average period					2 years 7 months 6 days
Expected dividend yield					0%	0%	0%
Weighted-average grant-date fair value					$ 18.25	$ 12.73	$ 13.39
2023 Executive PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation related to unvested stock, expected to recognize over weighted-average period					1 year 6 months
Granted	12,000	135,835
Award Vesting Rights Percentage		50%
Total unrecognized stock-based compensation					$ 2,100
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation related to unvested stock option awards granted					$ 19,600
Unrecognized stock-based compensation related to unvested stock, expected to recognize over weighted-average period					2 years 2 months 12 days
Restricted Common Stock Member | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued for services				562,500
Vested						122,464	133,593
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans, description					Shares subject to outstanding awards under the 2018 Plan as of the effective date of the 2019 Plan that are subsequently canceled, forfeited or repurchased by the Company will be added to the shares reserved under the 2019 Plan. In addition, the number of shares of common stock available for issuance under the 2019 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2019 Plan, beginning with January 1, 2020 and ending with January 1, 2029, by an amount equal to 5% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year or such lesser amount as determined by the Company’s board of directors. As of December 31, 2023, 1,119,312 shares of common stock were available for issuance under the 2019 Plan.
Shares of common stock expiration term			10 years
Shares of common stock beginning date			Jan. 01, 2020
Shares of common stock ending date			Jan. 01, 2029
Percentage of annual increase in common stock available for issuance			5%
Number of common stock for future issuance					1,119,312
2020 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock for future issuance					1,110,952				750,000
Number of additional common stock for future issuance					1,500,000		1,000,000	750,000
2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans, description					he number of shares of common stock available for issuance under the ESPP will be automatically increased on the first day of each calendar year during the first ten years of the term of the ESPP, beginning with January 1, 2020 and ending with January 1, 2029, by an amount equal to the lesser of (i) 1% of the outstanding number of shares of common stock on December 31st of the preceding calendar year, (ii) 1,500,000 shares of common stock or (iii) such lesser amount as determined by the Company’s board of directors. The ESPP became effective on July 17, 2019 and generally provides for six-month consecutive offering periods beginning on May 11th and November 11th of each year. During the year ended December 31, 2023, 116,742 shares were issued under the ESPP. As of December 31, 2023, the Company had 1,040,828 shares available for future issuance under the ESPP. The stock-based compensation related to the ESPP for the years ended December 31, 2023, 2022 and 2021 was $0.9 million, $0.7 million and $0.7 million, respectively.
Shares of common stock expiration term			10 years
Shares of common stock beginning date			Jan. 01, 2020
Shares of common stock ending date			Jan. 01, 2029
Percentage of annual increase in common stock available for issuance			1%
Number of common stock approved and reserved for issuance					1,040,828
Stock issued for services					116,742
Annual increase in common stock available for issuance, shares			1,500,000
2019 Employee Stock Purchase Plan | Executive Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 900	$ 700	$ 700

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options, Outstanding
Unvested and Outstanding as of December 31, 2022	8,340,083
Granted	2,066,089
Exercised	(514,443)
Canceled and forfeited	(259,225)
Unvested and Outstanding as of December 31, 2023	9,632,504	8,340,083
Vested and exercisable as of December 31, 2023	5,978,571
Weighted-average exercise price, Outstanding
Weighted-average exercise price, Outstanding, Beginning balance	$ 13.63
Weighted-average exercise price, Granted	25.35
Weighted-average exercise price, Exercised	16.09
Weighted-average exercise price, Cancelled and forfeited	18.8
Weighted-average exercise price, Outstanding, Ending balance	15.87	$ 13.63
Weighted-average exercise price, Vested and exercisable	$ 12.12
Share-based Payment Award, Options, Additional Disclosures
Weighted-average remaining contractual life, Outstanding	6 years 10 months 24 days	7 years 6 months
Weighted-average remaining contractual life, Vested and exercisable	5 years 10 months 24 days
Aggregate intrinsic value, Outstanding	$ 131,785	$ 51,645
Aggregate intrinsic value, Vested and exercisable	$ 104,048

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards Granted (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]
Expected volatility, minimum	80.17%	80.86%	82.76%
Expected volatility, maximum	85.24%	83.20%	94.06%
Risk-free interest rate, minimum	3.35%	1.46%	0.62%
Risk-free interest rate, maximum	4.67%	4.10%	1.34%
Expected dividend yield	0%	0%	0%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years 6 months	5 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested and Outstanding as of December 31, 2022	1,129,492	615,474
Granted	824,584
Vested	(245,783)
Canceled and forfeited	(64,783)
Unvested and Outstanding as of December 31, 2023	1,129,492	615,474
Weighted-average exercise price, Granted	$ 25.48
Weighted-average exercise price, Vested	18.36
Weighted-average exercise price, Cancelled and forfeited	20.82
Weighted-average exercise price, Vested and exercisable	$ 23.41	$ 18.36

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of PSU Activity (Details) - Performance Shares [Member]	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unvested and Outstanding as of December 31, 2022	0
Granted	147,835
Unvested and Outstanding as of December 31, 2023	147,835
Weighted-average exercise price, Granted | $ / shares	$ 23.64
Weighted-average exercise price, Vested and exercisable | $ / shares	$ 23.64

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-based Compensation Reflected in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 35,023	$ 27,007	$ 23,016
Selling, General and Administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	24,131	16,957	13,128
Research and Development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 10,892	$ 10,050	$ 9,888

Gain from Sale of Priority Re_2

Gain from Sale of Priority Review Voucher - Additional information (Details) - Priority review voucher of Livmarli [Member] - USD ($) $ in Millions	1 Months Ended
	Dec. 31, 2021	Nov. 30, 2021
Proceeds from sale of other investments		$ 110
Net proceeds after commision	$ 108

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Losses before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. loss before taxes	$ (164,953)	$ (142,661)	$ (84,217)
Foreign income before taxes	2,529	590	266
Net loss before provision for income taxes	$ (162,424)	$ (142,071)	$ (83,951)

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax (Expense) Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current income taxes:
Federal	$ 37	$ 0	$ 0
State	67	18	0
Foreign	887	157	37
Total current	991	175	37
Deferred taxes:
Federal	0	(5,503)	0
State	0	(1,078)	0
Total deferred	0	(6,581)	0
Income tax (benefit) expense	$ 991	$ (6,406)	$ 37

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax [Line Items]
Valuation allowance, deferred tax asset, increase	$ 40,200	$ 32,500	$ 23,900
Provision for income taxes	991	(6,406)	$ 37
Deferred tax assets, tax credit carryforwards, research and development	38,065	23,569
Income or foreign withholding taxes on Undistributed earnings of foreign subsidiaries	0	0
Satiogen
Income Tax [Line Items]
Business acquisition, deferred tax liability	6,600
Provision for income taxes		(6,600)
California Franchise Tax Board
Income Tax [Line Items]
Operating loss carryforwards	$ 59,700	17,700
Operating loss carryforwards expiration, beginning year	2038
Domestic Tax Authority
Income Tax [Line Items]
Operating loss carryforwards	$ 166,900	153,100
Deferred tax assets, tax credit carryforwards, research and development	36,500	32,500
State and Local Jurisdiction
Income Tax [Line Items]
Operating loss carryforwards	$ 30,000	19,100
Operating loss carryforwards expiration, beginning year	2032
State and Local Jurisdiction | California Franchise Tax Board
Income Tax [Line Items]
Deferred tax assets, tax credit carryforwards, research and development	$ 4,800	$ 4,200

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Federal Statutory Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21%	21%	21%
State tax	3.57%	7.40%	1.32%
Permanent differences	(0.50%)	(0.65%)	(1.70%)
Other	(0.13%)	(0.93%)	0.02%
Executive compensation	0%	(2.99%)	0%
Global intangible low-taxed income	(1.69%)	(1.43%)	0%
Tax credits	1.91%	4.96%	7.72%
Change in valuation allowance	(24.77%)	(22.85%)	(28.41%)
Total tax benefit	(0.61%)	4.51%	(0.05%)

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating losses	$ 40,455	$ 34,522
Capitalized research and development	38,065	23,569
Tax credit carryforwards	30,071	26,747
Interest limitation attributes	15,814	3,127
Stock-based compensation	8,419	6,726
Intangibles	4,055	4,733
Accrued expenses	3,953	3,101
Inventory	2,316	426
Lease liability	269	460
Total deferred tax assets	143,417	103,411
Deferred tax liabilities:
Operating lease right-of-use assets	(161)	(272)
Fixed assets	(37)	(100)
Total deferred tax liabilities	(198)	(372)
Valuation allowance	(143,219)	(103,039)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 9,254	$ 6,399
(Decrease) related to prior year tax positions	0	0
Increases related to current year tax positions	1,200	2,855
Balance at end of year	$ 10,454	$ 9,254