Mirum Pharmaceuticals (MIRM) 10-Q 5 May 22 2022 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 02, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity File Number	001-38981
Entity Registrant Name	Mirum Pharmaceuticals, Inc.
Entity Central Index Key	0001759425
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
Trading Symbol	MIRM
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		31,835,369
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common stock, par value $0.0001 per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 46,272	$ 31,340
Short-term investments	93,636	125,201
Accounts receivable	7,872	3,267
Inventory	1,580	1,513
Prepaid expenses and other current assets	5,908	5,271
Total current assets	155,268	166,592
Restricted Cash Equivalents	100,000	100,000
Long-term investments	0	4,983
Property and equipment, net	898	981
Operating lease right-of-use assets	1,468	1,569
Intangible assets, net	18,481	18,740
Other assets	2,033	1,786
Total assets	278,148	294,651
Current liabilities:
Accounts payable	4,943	9,166
Accrued expenses	26,883	30,723
Operating lease liabilities	731	711
Derivative liability	1,996	1,996
Total current liabilities	34,553	42,596
Revenue interest liability, net	132,940	129,923
Operating lease liabilities, noncurrent	1,713	1,903
Other liabilities	10	17
Total liabilities	169,216	174,439
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized, and zero shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized; 31,801,908 shares issued and 31,712,842 shares outstanding, excluding 89,066 shares subject to repurchase as of March 31, 2022; and 30,705,060 shares issued and 30,582,596 shares outstanding, excluding 122,464 shares subject to repurchase as of December 31, 2021	3	3
Additional paid-in capital	402,825	377,403
Accumulated deficit	(293,765)	(257,159)
Accumulated other comprehensive (loss) income	(131)	(35)
Total stockholders’ equity	108,932	120,212
Total liabilities and stockholders’ equity	$ 278,148	$ 294,651

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
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	31,801,908	30,705,060
Common stock, shares, outstanding	31,712,842	30,582,596
Common stock, subject to repurchase	89,066	122,464

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue	$ 12,892	$ 0
Operating expenses:
Cost of sales	2,424	0
Research and development	24,088	38,134
Selling, general and administrative	19,116	9,479
Total operating expenses	45,628	47,613
Loss from operations	(32,736)	(47,613)
Other income (expense):
Interest income	69	149
Interest expense	(3,774)	(3,381)
Change in fair value of derivative liability	0	334
Other income (expense), net	(154)	(16)
Net loss before provision for income taxes	(36,595)	(50,527)
Provision for income taxes	11	5
Net loss	$ (36,606)	$ (50,532)
Net loss per share, basic and diluted	$ (1.17)	$ (1.68)
Weighted-average shares of common stock outstanding, basic and diluted	31,296,223	30,105,017
Product [Member]
Revenue	$ 10,892	$ 0
License [Member]
Revenue	$ 2,000	$ 0

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (36,606)	$ (50,532)
Other comprehensive gain (loss):
Unrealized loss on available-for-sale investments	(93)	(74)
Cumulative translation adjustments	(3)	(9)
Comprehensive loss	$ (36,702)	$ (50,615)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	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 in connection with common stock option exercises	80		80
Issuance of common stock in connection with common stock option exercises, Shares		12,535
Issuance of common stock	7,038		7,038
Issuance of common stock, shares		375,654
Restricted common stock vested in the period, Shares		33,396
Stock-based compensation	5,285		5,285
Net loss	(50,532)			(50,532)
Other comprehensive loss	(83)				(83)
Balance at Mar. 31, 2021	133,883	$ 3	357,583	(223,703)
Balance, Shares at Mar. 31, 2021		30,198,129
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 in connection with equity award plans	1,477		1,477
Issuance of common stock in connection with equity award plans, Shares		100,951
Issuance of common stock	17,384		17,384
Issuance of common stock, shares		995,897
Restricted common stock vested in the period, Shares		33,398
Issuance of shares in connection with ESPP	1,477		1,477
Issuance of shares in connection with ESPP, Shares		100,951
Stock-based compensation	6,561		6,561
Net loss	(36,606)			(36,606)
Other comprehensive loss	(96)				(96)
Balance at Mar. 31, 2022	$ 108,932	$ 3	$ 402,825	$ (293,765)	$ (131)
Balance, Shares at Mar. 31, 2022		31,712,842

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Common Stock
Issuance of common stock upon public offering, issuance costs	$ 601	$ 476

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net loss	$ (36,606)	$ (50,532)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation	6,561	5,285
Depreciation and amortization	342	90
Amortization of operating lease right-of-use assets	101	95
Net (accretion) amortization of discounts on investments	(45)	6
Non-cash interest expense related to the revenue interest liability	3,774	3,381
Change in fair value of derivative liability	0	(334)
Change in operating assets and liabilities:
Accounts receivable	(4,605)	0
Prepaid expenses and other current assets	(637)	(112)
Inventory	(67)	0
Other assets	(247)	(160)
Accounts payable, accrued expenses and other liabilities	(8,070)	17,228
Operating lease liabilities	(170)	(157)
Net cash used in operating activities	(39,669)	(25,210)
Investing activities
Proceeds from maturities of investments	36,500	48,600
Proceeds from paydown of investments	0	2,000
Purchase of investments	0	(83,381)
Purchase of property and equipment	0	(3)
Net cash provided by (used in) provided by investing activities	36,500	(32,784)
Financing activities
Proceeds from issuance of common stock in public offerings, net of issuance costs	17,384	6,914
Proceeds from issuance of common stock pursuant to equity award plans	1,477	80
Payment of issuance costs related to the revenue interest liability	0	(400)
Payments on revenue interest liability	(757)	0
Net cash provided by financing activities	18,104	6,594
Effect of exchange rate on cash, cash equivalents and restricted cash equivalents	(3)	(9)
Net increase (decrease) in cash, cash equivalents and restricted cash equivalents	14,932	(51,409)
Cash, cash equivalents and restricted cash equivalents at beginning of period	131,340	142,086
Cash, cash equivalents and restricted cash equivalents at end of period	146,272	90,677
Supplemental disclosure of cash flow information:
Operating cash flows paid for operating lease	$ 219	$ 212

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2022
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 received U.S. Food and Drug Administration (“FDA”) approval for LIVMARLI® (maralixibat) oral solution (“Livmarli”), the first and only FDA-approved medication for the treatment of cholestatic pruritus in patients with Alagille syndrome (“ALGS”) one year of age and older, on September 29, 2021. The Company’s development pipeline consists of two clinical-stage product candidates, Livmarli and volixibat. The Company commenced significant operations in November 2018. The Company views its operations and manages its business as one operating segment. 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 March 31, 2022, the Company had an accumulated deficit of $ 293.8 million and cash, cash equivalents, restricted cash equivalents and investments of $ 239.9 million. The Company believes that its cash, unrestricted cash equivalents and investments of $ 139.9 million as of March 31, 2022 provide sufficient capital resources to continue its operations for at least twelve months from the issuance date of the accompanying unaudited condensed consolidated financial statements. The unaudited condensed 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 unaudited condensed 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying unaudited condensed consolidated financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The consolidated balance sheet as of December 31, 2021 has been derived from the audited consolidated financial statements at that date but does not include all information and footnotes required by GAAP for complete financial statements. The operating results presented in these unaudited condensed consolidated financial statements are not necessarily indicative of the results that may be expected for any future periods. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K (“Annual Report”) for the fiscal year ended December 31, 2021, as filed with the SEC on March 9, 2022. 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. In December 2019, a novel strain of coronavirus, which causes COVID-19, was identified. Due to the rapid and global spread of the virus, on March 11, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. To slow the proliferation of COVID-19, governments have implemented extraordinary measures, which include the mandatory closure of businesses, restrictions on travel and gatherings, and quarantine and physical distancing requirements. There were no significant estimates contained in the preparation of the Company’s unaudited condensed consolidated financial statements or impacts to the Company’s unaudited condensed consolidated financial statements that were directly a result of the COVID-19 pandemic. 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 . Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2022 , as compared to the significant accounting policies described in Note 2 of the “Notes to Consolidated Financial Statements” in the Company’s audited consolidated financial statements included in the Annual Report, except as discussed below. 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 condensed consolidated balance sheets for cash and cash equivalents are valued at cost, which approximate their fair value. Restricted cash equivalents consists of deposits placed in a segregated bank account as required under the terms of the Company’s Revenue Interest Purchase Agreement (“RIPA”), as amended September 2021, with Mulholland SA LLC, an affiliate of Oberland Capital LLC, as agent for the purchasers party thereto (the “Purchasers”), and the Purchasers in connection with the sale of a Rare Pediatric Disease Priority Review Voucher in December 2021. The following table provides a reconciliation of cash, cash equivalents and restricted cash equivalents reported within the unaudited condensed consolidated balance sheets that together reflect the same amounts shown in the unaudited condensed consolidated statements of cash flows (in thousands): As of March 31, As of December 31, 2022 2021 Cash and cash equivalents $ 46,272 $ 31,340 Restricted cash equivalents 100,000 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 146,272 $ 131,340 Intangible Assets, Net Upon FDA approval of Livmarli in September 2021, contractual milestone payments for which the Company was then-obligated to pay to licensors were evaluated as intangible assets for the completed regulatory approval and right to commercialize the product. 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. The Company determined the pattern of this intangible asset’s future cash flows could not be readily determined with a high level of precision. As a result, the intangible asset is being amortized on a straight-line basis over the estimated useful life of 18 years . The Company tests its definite lived intangible assets for impairment annually and 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 becomes impaired, the carrying value is written down to its fair value with the related impairment charge recognized in the condensed consolidated statements of operations in the period in which the impairment occurs. The Company has not recorded any impairments to its intangible assets. The following table provides detail of the carrying amount of the Company's intangible assets (in thousands): March 31, December 31, 2022 2021 Gross carrying value $ 19,000 $ 19,000 Less accumulated amortization ( 519 ) ( 260 ) Net carrying value $ 18,481 $ 18,740 Amortization expense was $ 0.3 million and zero for the three months ended March 31, 2022 and 2021, respectively, and was included in cost of sales on our accompanying unaudited condensed consolidated statements of operations. The following table summarizes the estimated future amortization expense associated with our intangible assets as of March 31, 2022 (in thousands): Amount 2022 (remaining nine months) $ 779 2023 1,038 2024 1,038 2025 1,038 2026 1,038 Thereafter 13,550 $ 18,481 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 Livmarli. Estimates of variable consideration are calculated based on the actual product sales each reporting period. 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 in the accompanying unaudited condensed 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 Livmarli 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. Net Loss Per Share Basic net loss per share is computed by dividing net loss attributable to common stockholders 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 attributable to common stockholders 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, and contingently issuable employee stock purchase plan shares because their effect would be anti-dilutive due to the Company’s net loss. Since the Company incurred a net loss in each of the periods presented, basic and diluted net loss per share were the same. The following outstanding potentially 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 March 31, As of December 31, 2022 2021 Options to purchase common stock and restricted stock units 8,591,673 6,940,566 Common stock subject to repurchase 89,066 122,464 Employee stock purchase plan contingently issuable 57,381 23,116 Total 8,738,120 7,086,146 Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued 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 requires the use of forward-looking expected credit loss models based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount, which may result in earlier recognition of credit losses under the new guidance. The new guidance also modifies the impairment models for available-for-sale debt securities and for purchased financial assets with credit deterioration since their origination. Subsequent to the issuance of ASU 2016-13, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses . This ASU does not change the core principle of the guidance in ASU 2016-13, instead these amendments are intended to clarify and improve operability of certain topics included within the credit losses guidance. The FASB also subsequently issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Derivatives and Hedging (Topic 815), and Financial Instruments (Topic 842), which did not change the core principle of the guidance in ASU 2016-13 but clarified that expected recoveries of amounts previously written off and expected to be written off should be included in the valuation account and should not exceed amounts previously written off and expected to be written off. In March 2020, the 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 guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019 for public business entities, excluding smaller reporting companies. For smaller reporting companies, the guidance will be effective during the first quarter of 2023. The Company is in the process of assessing the impact adoption will have on its consolidated financial statements. In October 2021, the FASB, issued Accounting Standards Update No. 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , which requires an entity (acquirer) to recognize and measure contract assets and liabilities acquired in a business combination in accordance with Topic 606, Revenue from Contracts with Customers . This update is effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied prospectively to business combinations occurring on or after the effective date of the amendments. The Company is currently evaluating the impact the standard will have on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
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): March 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 143,853 $ — $ — $ 143,853 Commercial paper — 78,765 — 78,765 U.S. government bonds — 14,870 — 14,870 Total financial assets $ 143,853 $ 93,635 $ — $ 237,488 Financial liabilities: Derivative liability — — 1,996 1,996 Total financial liabilities $ — $ — $ 1,996 $ 1,996 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 128,420 $ — $ — $ 128,420 Commercial paper — 115,221 — 115,221 U.S. government bonds — 14,963 — 14,963 Total financial assets $ 128,420 $ 130,184 $ — $ 258,604 Financial liabilities: Derivative liability — — 1,996 1,996 Total financial liabilities $ — $ — $ 1,996 $ 1,996 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 March 31, 2022 and December 31, 2021 approximate their related fair values due to the short-term maturities of these instruments. Certain financial instruments classified within Level 2 of the fair value hierarchy include the types of instruments that trade in markets that are not considered to be active, but are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The carrying amount of the revenue interest liability as of March 31, 2022 and December 31, 2021 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. The derivative liability is considered a Level 3 input based on the three-level hierarchy. Refer to Note 6 “Revenue Interest Purchase Agreement” for further information. Derivative Liability The debt pursuant to the RIPA contains embedded derivatives 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 March 31, 2022 and December 31, 2021. The estimated probability and timing of underlying events triggering the exercisability of the put options contained within the RIPA, forecasted cash flows and the discount rate are significant unobservable inputs used to determine the estimated fair value of the entire instrument with the embedded derivative. As of March 31, 2022 and December 31, 2021, the discount rate used for valuation of the derivative liability was 15.7 %. The following table provides a summary of the change in the estimated fair value of the Company’s derivative liability, classified as Level 3 in the fair value hierarchy (in thousands): Balance at December 31, 2021 $ 1,996 Change in fair value of derivative liability — Balance at March 31, 2022 $ 1,996

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2022
Financial Instruments, Owned, at Fair Value [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): March 31, 2022 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 143,853 $ — $ — $ 143,853 Commercial paper 78,765 — — 78,765 U.S. government bonds 14,999 — ( 129 ) 14,870 Total cash equivalents and investments $ 237,617 $ — $ ( 129 ) $ 237,488 Classified as: Cash equivalents $ 43,852 Cash equivalents - restricted 100,000 Short-term investments 93,636 Total cash equivalents, restricted cash equivalents and investments $ 237,488 December 31, 2021 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 128,420 $ — $ — $ 128,420 Commercial paper 115,221 — — 115,221 U.S. government bonds 14,999 — ( 36 ) 14,963 Total cash equivalents and investments $ 258,640 $ — $ ( 36 ) $ 258,604 Classified as: Cash equivalents $ 28,420 Cash equivalents - restricted 100,000 Short-term investments 125,201 Long-term investments 4,983 Total cash equivalents, restricted cash equivalents and investments $ 258,604 As of March 31, 2022, the remaining contractual maturities of available-for-sale debt securities were as follows: (in thousands): Estimated Due within one year $ 93,636 One to two years — Total $ 93,636 During the three months ended March 31, 2022 and 2021 , there have been no significant realized gains or losses on available-for-sale investments, no investments had been in a continuous unrealized loss position for more than 12 months, and the Company did no t recognize any other-than-temporary impairment losses on these securities.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2022
Balance Sheet Components [Abstract]
Balance Sheet Components	5. Balance Sheet Components Inventory The following is a summary of the Company’s inventory by category (in thousands): March 31, December 31, 2022 2021 Raw material $ 858 $ 856 Work in progress 553 570 Finished goods 169 87 Total inventory $ 1,580 $ 1,513 Accrued Expenses Accrued expenses consist of the following (in thousands): March 31, December 31, 2022 2021 Accrued clinical trials $ 8,418 $ 6,732 Accrued professional service fees 4,961 2,458 Accrued contract manufacturing and non-clinical costs 5,079 4,635 Accrued compensation and related benefits 5,600 9,988 Accrued rebates payable 1,654 265 Accrued royalties payable 1,171 345 Accrued collaboration funding — 6,300 Total accrued expenses $ 26,883 $ 30,723

Revenue Interest Purchase Agree

Revenue Interest Purchase Agreement	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue Interest Purchase Agreement	6. Revenue Interest Purchase Agreement In December 2020, the Company entered into the RIPA, as amended in September 2021, with Mulholland SA LLC, an affiliate of Oberland Capital LLC, 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. The Company may also be 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. The Company was entitled to receive an additional $ 35.0 million upon FDA approval of Livmarli, which it elected to forgo. As consideration for such payments, the Purchasers have the right to receive certain revenue interests (the “Revenue Interests”) from the Company based on annual product sales, net of Livmarli, which will be tiered payments (the “Revenue Interest Payments”) based on whether such annual product sales, net are (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 will initially be 9.75 % (at Tier 1) and 2.0 % (at Tier 2 and Tier 3) of such annual net sales. If the Purchasers have received Revenue Interest Payments in an amount equal to or greater than 110.0% of the total payments actually made by the Purchasers to the Company, exclusive of transaction expenses (the “Cumulative Purchaser Payments”), on or prior to December 31, 2026, the Revenue Interests shall be reduced to 2.0 % at Tier 1 and 0.0 % at Tier 3 for all subsequent calendar years beginning on January 1, 2027. If the Purchasers have not received Revenue Interest Payments in an amount equal to or greater than 110.0 % of the Cumulative Purchaser Payments on or prior to December 31, 2026, the Revenue Interests shall be increased for all subsequent calendar years beginning on January 1, 2027 to a single defined rate (with no separate tiers) that would have provided the Purchasers with an amount equal to 110.0% of the Cumulative Purchaser Payments on or prior to December 31, 2026 had such rate applied to Tier 1 of initial Revenue Interest Payments. The Purchasers’ rights to receive the Revenue Interest Payments shall terminate on the date on which the Purchasers have received Revenue Interest Payments of 195.0 % of the Cumulative Purchaser Payments, unless the RIPA is terminated earlier. Under the RIPA, the Company has an option (the “Call Option”) to terminate the RIPA and repurchase future Revenue Interests at any time upon advance written notice. Additionally, the Purchasers have 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 will be 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 will be 175.0 % 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 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 contains 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 Purchaser’s obligations to fund the scheduled installments are 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 Options under the RIPA that are exercisable by Purchasers upon certain contingent events were determined to be embedded derivatives 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 will be amortized to interest expense over the expected term of the debt using the effective interest method. As of March 31, 2022 and December 31, 2021, $ 132.9 million and $ 129.9 million, respectively, was recorded as a revenue interest liability on the accompanying unaudited condensed consolidated balance sheets. The Company imputes interest expense associated with this liability using the effective interest rate method. The effective interest rate is 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 may vary during the term of the agreement depending on a number of factors, including the level of forecasted product sales, net. The Company evaluates the interest rate quarterly based on its current product sales, net forecasts utilizing the prospective method. A significant increase or decrease in product sales, net will materially impact the revenue interest liability, interest expense and the time period for repayment. The Company recorded $ 3.8 million and $ 3.4 million in interest expense related to this arrangement for the three months ended March 31, 2022 and 2021, respectively. The Company incurred $ 0.9 million of issuance costs in connection with the RIPA, which are amortized to interest expense over the estimated term of the debt. Revenue Interest Payments made as a result of the Company’s product sales, net reduce the revenue interest liability. The following table summarizes the revenue interest liability activity during the three months ended March 31, 2022 (in thousands): Revenue interest liability at December 31, 2021 $ 129,923 Interest expense recognized 3,774 Revenue interest payments ( 757 ) Revenue interest liability at March 31, 2022 $ 132,940

Asset Acquisitions

Asset Acquisitions	3 Months Ended
	Mar. 31, 2022
Asset Acquisitions [Abstract]
Asset Acquisitions	7. Asset Acquisitions 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, and made an upfront payment to Shire of $ 7.5 million and issued Shire 1,859,151 shares of redeemable common stock with an estimated fair value of $ 7.0 million, or $ 3.76 per share. 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 Pharmaceuticals, Inc. (“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. There were no Livmarli development or regulatory milestones achieved during the three months ended March 31, 2022 compared to $ 15.0 million for the three months ended March 31, 2021. There were no volixibat development and regulatory milestones achieved during the three months ended March 31, 2022 compared to $ 2.0 million for the three months ended March 31, 2021. As of March 31, 2022, no milestones had been accrued as there were no potential milestones yet considered probable. 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. The Company is 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 will be required to pay a low single-digit royalty on net sales. The Company’s royalty obligations continue 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 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 March 31, 2022, no milestones had been accrued as there were no potential milestones yet considered probable. 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 March 31, 2022 , no milestones had been accrued as there were no potential milestones considered probable.

Collaboration and License Agree

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2022
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, was recorded as license revenue in the accompanying consolidated statements of operations. 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 (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 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. For the three months ended March 31, 2022, no adjustments were made to the transaction price. For the three months ended March 31, 2022, the Company recorded research and development funding of $ 0.4 million, payable by CANbridge to the Company which is reflected as a reduction of research and development expense in the accompanying unaudited condensed consolidated statements of operations. As of March 31, 2022, such research and development funding of $ 1.2 million was recorded as a receivable which was included in prepaids and other current assets on the accompanying unaudited condensed consolidated balance sheets. In January 2022, CANbridge achieved a regulatory milestone, triggering a milestone payment to the Company of $ 2.0 million, which is recorded as license revenue on the accompanying unaudited condensed consolidated statement of operations for the three months ended March 31, 2022. 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, progressive familial intrahepatic cholestasis (“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 in the accompanying unaudited condensed consolidated financial statements of operations. 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 will re-evaluate the transaction price at each reporting period as uncertain events are resolved and other changes in circumstances occur. For the three months ended March 31, 2022, no adjustments were made to the transaction price. Licensing Agreement with Takeda In September 2021, the Company entered into an exclusive licensing agreement with Takeda Pharmaceutical Company Limited (“ 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. Option, License and Collaboration Agreement with Vivet In April 2021 , the Company entered into an Option, License and Collaboration Agreement (“Vivet Collaboration Agreement”) with Vivet Therapeutics SAS (“Vivet”). Pursuant to the Vivet Collaboration Agreement, Vivet granted the Company the exclusive option, at the Company's discretion, to develop and subsequently commercialize Vivet’s two proprietary AAV gene therapy programs for PFIC, subtypes 3 and 2. Under the terms of the Vivet Collaboration Agreement, the Company paid an upfront fee of $ 4.2 million and agreed to provide funding to support certain research and development costs associated with the two gene therapy programs through July 2023. In December 2021, the Company elected not to exercise its option, terminating the agreement. The Company made a final payment of $ 6.3 million in January 2022 under the terms of the agreement, which was reflected in accrued expenses at December 31, 2021 on the accompanying unaudited condensed consolidated balance sheets.

Leases

Leases	3 Months Ended
	Mar. 31, 2022
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 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. The lease contained a tenant improvement allowance of $ 0.4 million, which has been recorded as leasehold improvements in the accompanying unaudited condensed consolidated balance sheets with a corresponding reduction of the right-of-use (“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 lease 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 unaudited condensed 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 March 31, 2022 , the Company recorded an aggregate ROU asset of $ 1.5 million and an aggregate lease liability of $ 2.4 million in the accompanying unaudited condensed consolidated balance sheets. The weighted-average remaining lease term is 2.9 years. As of March 31, 2022, undiscounted future minimum payments under the Company’s operating leases are as follows (in thousands): Undiscounted 2022 (remaining nine months) $ 670 2023 918 2024 926 2025 230 Total undiscounted lease payments 2,744 Less: imputed interest ( 300 ) Total lease liability $ 2,444 Rent expense was $ 0.2 million for the three months ended March 31, 2022 and 2021. Variable lease payments for operating expenses were immaterial for the three months ended March 31, 2022 and 2021 .

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Stockholders' Equity	10. Stockholders’ Equity Common Stock In August 2020, the SEC declared effective a registration statement on Form S-3 (“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 (“Sales Agreement”) with SVB Securities LLC (“SVB Securities”) pursuant to which the Company may elect to issue and sell, from time to time, in an at the market offering, shares of common stock having an aggregate offering price of up to $ 75.0 million under the Shelf Registration through SVB Securities acting as the sales agent and/or principal. During the three months ended March 31, 2022, the Company issued and sold 995,897 shares of common stock pursuant to the Sales Agreement at a weighted-average price of $ 18.06 per share, resulting in aggregate gross proceeds to the Company of $ 18.0 million. The net proceeds to the Company after deducting sales commissions to SVB Securities and other issuance expenses were approximately $ 17.4 million. As of March 31, 2022, the Company issued and sold an aggregate of 1,301,866 shares of common stock pursuant to the Sales Agreement at a weighted-average price of $ 18.88 per share, resulting in aggregate gross proceeds to the Company of $ 24.6 million. The net proceeds to the Company after deducting sales commissions to SVB Securities and other issuance expenses were approximately $ 23.7 million. The remaining capacity under the Sales Agreement is approximately $ 50.4 million as of March 31, 2022. In December 2020, the Company completed an underwritten public offering of its common stock pursuant to the Shelf Registration. The Company sold 3,750,000 shares of common stock at a price of $ 20.00 per share, resulting in net proceeds of $ 70.0 million after deducting underwriting discounts, commissions and offering expenses. In addition, the Company granted the underwriters an option, exercisable for 30 days, to purchase up to 562,500 additional shares of its common stock at the public offering price, less the underwriting discounts and commissions. In January 2021, the underwriters partially exercised their option and purchased 375,654 shares of the Company’s common stock at a price of $ 20.00 per share, resulting in net proceeds of $ 7.1 million after deducting underwriting discounts. As of March 31, 2022 and December 31, 2021, 89,066 shares and 122,464 shares of common stock, respectively, were subject to repurchase by the Company. The unvested stock liability related to these shares is immaterial to all periods presented. Common Stock Reserved for Issuance Common stock reserved for issuance is as follows: As of March 31, As of December 31, 2022 2021 Stock options and restricted stock units issued and outstanding 8,591,673 6,940,566 Reserved for future stock awards or option grants 2,217,814 2,434,619 Reserved for employee stock purchase plan 1,218,188 911,138 12,027,675 10,286,323

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	11. 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 (“RSUs”) 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 March 31, 2022 , 1,218,738 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 RSUs 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 2021 and 2020, the Company’s board of directors authorized an additional 1,000,000 and 750,000 shares of the Company’s common stock for future issuance, respectively. As of March 31, 2022 , 999,076 shares of common stock were available for issuance under the 2020 Inducement Plan. Stock Options The following table summarizes stock option activity during the three months ended March 31, 2022 (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2021 6,870,617 $ 12.56 8.0 $ 32,637 Granted 1,481,550 $ 16.01 Exercised ( 100,951 ) $ 14.63 Canceled and forfeited ( 102,954 ) $ 17.24 Outstanding as of March 31, 2022 8,148,262 $ 13.10 8.1 $ 73,027 Vested and exercisable as of March 31, 2022 3,507,360 $ 9.65 7.2 $ 43,567 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 three months ended March 31, 2022 and 2021 was $ 11.27 and $ 14.55 per share, respectively. The total intrinsic value of options exercised during the three months ended March 31, 2022 and 2021 was $ 0.8 million and $ 0.2 million, re spectively. As of March 31, 2022, the total unrecognized stock-based compensation related to unvested stock option awards granted was $ 50.8 million, which the Company expects to recognize over a weighted-average period of approximate ly 2.8 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 Company estimated expected volatility based on the historical volatility of a group of similar companies that are publicly traded. The historical volatility data was computed using the daily closing prices for the selected 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: Three Months Ended March 31, 2022 2021 Exercise price $ 15.50 -$ 22.41 $ 18.41 -$ 21.22 Expected term (in years) 6.08 6.08 Expected volatility 81.69 %- 82.32 % 93.24 %- 94.06 % Risk-free interest rate 1.46 %- 2.0 % 0.62 %- 1.34 % Expected dividend yield — — Restricted Stock Units The following table summarizes the activity under the Company's RSUs for the three months ended March 31, 2022: Number of Weighted-Average Grant Date Unvested and Outstanding as of December 31, 2021 69,949 $ 18.57 Granted 382,475 $ 16.11 Vested — $ - Cancelled/Forfeited ( 9,013 ) $ 16.50 Unvested and Outstanding as of March 31, 2022 443,411 16.48 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”). The ESPP became effective on July 17, 2019. A total of 500,000 shares of common stock were approved to be initially reserved for issuance under the ESPP. In addition, the 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. There were no shares issued under the ESPP for the three months ended March 31, 2022. As of March 31, 2022 , the Company had 1,218,188 shares available for future issuance under the ESPP. The stock-based compensation related to the ESPP was $ 0.2 million for the three months ended March 31, 2022 and 2021. Restricted 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. The modified shares have a four-year vesting period and a measurement date fair value of $ 2.94 per share. For the three months ended March 31, 2022 and 2021 , 33,398 shares and 33,396 sha res vested, respectively. As of March 31, 2022 , the total unrecognized compensation expense related to unvested restricted stock was $ 0.3 million expected to be recognized over a weighted-average period of approximately 0.6 year. Total stock-based compensation is reflected in the unaudited condensed consolidated statements of operations as follows (in thousands): Three Months Ended March 31, 2022 2021 Selling, general and administrative $ 3,976 $ 2,542 Research and development 2,585 2,743 Total $ 6,561 $ 5,285

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Contingencies	12. Contingencies 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)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying unaudited condensed consolidated financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The consolidated balance sheet as of December 31, 2021 has been derived from the audited consolidated financial statements at that date but does not include all information and footnotes required by GAAP for complete financial statements. The operating results presented in these unaudited condensed consolidated financial statements are not necessarily indicative of the results that may be expected for any future periods. The accompanying unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K (“Annual Report”) for the fiscal year ended December 31, 2021, as filed with the SEC on March 9, 2022.
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. In December 2019, a novel strain of coronavirus, which causes COVID-19, was identified. Due to the rapid and global spread of the virus, on March 11, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. To slow the proliferation of COVID-19, governments have implemented extraordinary measures, which include the mandatory closure of businesses, restrictions on travel and gatherings, and quarantine and physical distancing requirements. There were no significant estimates contained in the preparation of the Company’s unaudited condensed consolidated financial statements or impacts to the Company’s unaudited condensed consolidated financial statements that were directly a result of the COVID-19 pandemic. 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 .
Significant Accounting Policies	Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2022 , as compared to the significant accounting policies described in Note 2 of the “Notes to Consolidated Financial Statements” in the Company’s audited consolidated financial statements included in the Annual Report, except as discussed below.
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 condensed consolidated balance sheets for cash and cash equivalents are valued at cost, which approximate their fair value. Restricted cash equivalents consists of deposits placed in a segregated bank account as required under the terms of the Company’s Revenue Interest Purchase Agreement (“RIPA”), as amended September 2021, with Mulholland SA LLC, an affiliate of Oberland Capital LLC, as agent for the purchasers party thereto (the “Purchasers”), and the Purchasers in connection with the sale of a Rare Pediatric Disease Priority Review Voucher in December 2021. The following table provides a reconciliation of cash, cash equivalents and restricted cash equivalents reported within the unaudited condensed consolidated balance sheets that together reflect the same amounts shown in the unaudited condensed consolidated statements of cash flows (in thousands): As of March 31, As of December 31, 2022 2021 Cash and cash equivalents $ 46,272 $ 31,340 Restricted cash equivalents 100,000 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 146,272 $ 131,340
Revenue Recognition	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 Livmarli. Estimates of variable consideration are calculated based on the actual product sales each reporting period. 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 in the accompanying unaudited condensed 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 Livmarli 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.
Intangibles Assets, Net	Intangible Assets, Net Upon FDA approval of Livmarli in September 2021, contractual milestone payments for which the Company was then-obligated to pay to licensors were evaluated as intangible assets for the completed regulatory approval and right to commercialize the product. 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. The Company determined the pattern of this intangible asset’s future cash flows could not be readily determined with a high level of precision. As a result, the intangible asset is being amortized on a straight-line basis over the estimated useful life of 18 years . The Company tests its definite lived intangible assets for impairment annually and 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 becomes impaired, the carrying value is written down to its fair value with the related impairment charge recognized in the condensed consolidated statements of operations in the period in which the impairment occurs. The Company has not recorded any impairments to its intangible assets. The following table provides detail of the carrying amount of the Company's intangible assets (in thousands): March 31, December 31, 2022 2021 Gross carrying value $ 19,000 $ 19,000 Less accumulated amortization ( 519 ) ( 260 ) Net carrying value $ 18,481 $ 18,740 Amortization expense was $ 0.3 million and zero for the three months ended March 31, 2022 and 2021, respectively, and was included in cost of sales on our accompanying unaudited condensed consolidated statements of operations. The following table summarizes the estimated future amortization expense associated with our intangible assets as of March 31, 2022 (in thousands): Amount 2022 (remaining nine months) $ 779 2023 1,038 2024 1,038 2025 1,038 2026 1,038 Thereafter 13,550 $ 18,481
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing net loss attributable to common stockholders 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 attributable to common stockholders 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, and contingently issuable employee stock purchase plan shares because their effect would be anti-dilutive due to the Company’s net loss. Since the Company incurred a net loss in each of the periods presented, basic and diluted net loss per share were the same. The following outstanding potentially 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 March 31, As of December 31, 2022 2021 Options to purchase common stock and restricted stock units 8,591,673 6,940,566 Common stock subject to repurchase 89,066 122,464 Employee stock purchase plan contingently issuable 57,381 23,116 Total 8,738,120 7,086,146
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued 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 requires the use of forward-looking expected credit loss models based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount, which may result in earlier recognition of credit losses under the new guidance. The new guidance also modifies the impairment models for available-for-sale debt securities and for purchased financial assets with credit deterioration since their origination. Subsequent to the issuance of ASU 2016-13, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses . This ASU does not change the core principle of the guidance in ASU 2016-13, instead these amendments are intended to clarify and improve operability of certain topics included within the credit losses guidance. The FASB also subsequently issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Derivatives and Hedging (Topic 815), and Financial Instruments (Topic 842), which did not change the core principle of the guidance in ASU 2016-13 but clarified that expected recoveries of amounts previously written off and expected to be written off should be included in the valuation account and should not exceed amounts previously written off and expected to be written off. In March 2020, the 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 guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019 for public business entities, excluding smaller reporting companies. For smaller reporting companies, the guidance will be effective during the first quarter of 2023. The Company is in the process of assessing the impact adoption will have on its consolidated financial statements. In October 2021, the FASB, issued Accounting Standards Update No. 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers , which requires an entity (acquirer) to recognize and measure contract assets and liabilities acquired in a business combination in accordance with Topic 606, Revenue from Contracts with Customers . This update is effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied prospectively to business combinations occurring on or after the effective date of the amendments. The Company is currently evaluating the impact the standard will have on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
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 unaudited condensed consolidated balance sheets that together reflect the same amounts shown in the unaudited condensed consolidated statements of cash flows (in thousands): As of March 31, As of December 31, 2022 2021 Cash and cash equivalents $ 46,272 $ 31,340 Restricted cash equivalents 100,000 100,000 Total cash, cash equivalents, and restricted cash equivalents $ 146,272 $ 131,340
Schedule Of Finite Lived Intangible Assets	The following table provides detail of the carrying amount of the Company's intangible assets (in thousands): March 31, December 31, 2022 2021 Gross carrying value $ 19,000 $ 19,000 Less accumulated amortization ( 519 ) ( 260 ) Net carrying value $ 18,481 $ 18,740
Schedule of Estimated Future Amortization Expense Associated with Intangible Assets	The following table summarizes the estimated future amortization expense associated with our intangible assets as of March 31, 2022 (in thousands): Amount 2022 (remaining nine months) $ 779 2023 1,038 2024 1,038 2025 1,038 2026 1,038 Thereafter 13,550 $ 18,481
Summary of Outstanding Potentially Dilutive Shares of Common Stock Excluded from Calculation of Diluted Net Loss Per Share	The following outstanding potentially 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 March 31, As of December 31, 2022 2021 Options to purchase common stock and restricted stock units 8,591,673 6,940,566 Common stock subject to repurchase 89,066 122,464 Employee stock purchase plan contingently issuable 57,381 23,116 Total 8,738,120 7,086,146

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
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): March 31, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 143,853 $ — $ — $ 143,853 Commercial paper — 78,765 — 78,765 U.S. government bonds — 14,870 — 14,870 Total financial assets $ 143,853 $ 93,635 $ — $ 237,488 Financial liabilities: Derivative liability — — 1,996 1,996 Total financial liabilities $ — $ — $ 1,996 $ 1,996 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 128,420 $ — $ — $ 128,420 Commercial paper — 115,221 — 115,221 U.S. government bonds — 14,963 — 14,963 Total financial assets $ 128,420 $ 130,184 $ — $ 258,604 Financial liabilities: Derivative liability — — 1,996 1,996 Total financial liabilities $ — $ — $ 1,996 $ 1,996
Summary of Change in Estimated Fair Value of Company's Derivative Liability Classified as Level 3	The following table provides a summary of the change in the estimated fair value of the Company’s derivative liability, classified as Level 3 in the fair value hierarchy (in thousands): Balance at December 31, 2021 $ 1,996 Change in fair value of derivative liability — Balance at March 31, 2022 $ 1,996

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2022
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): March 31, 2022 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 143,853 $ — $ — $ 143,853 Commercial paper 78,765 — — 78,765 U.S. government bonds 14,999 — ( 129 ) 14,870 Total cash equivalents and investments $ 237,617 $ — $ ( 129 ) $ 237,488 Classified as: Cash equivalents $ 43,852 Cash equivalents - restricted 100,000 Short-term investments 93,636 Total cash equivalents, restricted cash equivalents and investments $ 237,488 December 31, 2021 Amortized Unrealized Unrealized Estimated Cash equivalents and investments: Money market fund $ 128,420 $ — $ — $ 128,420 Commercial paper 115,221 — — 115,221 U.S. government bonds 14,999 — ( 36 ) 14,963 Total cash equivalents and investments $ 258,640 $ — $ ( 36 ) $ 258,604 Classified as: Cash equivalents $ 28,420 Cash equivalents - restricted 100,000 Short-term investments 125,201 Long-term investments 4,983 Total cash equivalents, restricted cash equivalents and investments $ 258,604
Remaining contractual maturities of available-for-sale debt securities	As of March 31, 2022, the remaining contractual maturities of available-for-sale debt securities were as follows: (in thousands): Estimated Due within one year $ 93,636 One to two years — Total $ 93,636

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2022
Balance Sheet Components [Abstract]
Schedule Of Inventory	Inventory The following is a summary of the Company’s inventory by category (in thousands): March 31, December 31, 2022 2021 Raw material $ 858 $ 856 Work in progress 553 570 Finished goods 169 87 Total inventory $ 1,580 $ 1,513
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): March 31, December 31, 2022 2021 Accrued clinical trials $ 8,418 $ 6,732 Accrued professional service fees 4,961 2,458 Accrued contract manufacturing and non-clinical costs 5,079 4,635 Accrued compensation and related benefits 5,600 9,988 Accrued rebates payable 1,654 265 Accrued royalties payable 1,171 345 Accrued collaboration funding — 6,300 Total accrued expenses $ 26,883 $ 30,723

Revenue Interest Purchase Agr_2

Revenue Interest Purchase Agreement (Tables)	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Revenue Interest Liability	The following table summarizes the revenue interest liability activity during the three months ended March 31, 2022 (in thousands): Revenue interest liability at December 31, 2021 $ 129,923 Interest expense recognized 3,774 Revenue interest payments ( 757 ) Revenue interest liability at March 31, 2022 $ 132,940

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Schedule of Undiscounted Future Minimum Payments under Operating Leases	As of March 31, 2022, undiscounted future minimum payments under the Company’s operating leases are as follows (in thousands): Undiscounted 2022 (remaining nine months) $ 670 2023 918 2024 926 2025 230 Total undiscounted lease payments 2,744 Less: imputed interest ( 300 ) Total lease liability $ 2,444

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Schedule of Common Stock Reserved for Issuance	Common stock reserved for issuance is as follows: As of March 31, As of December 31, 2022 2021 Stock options and restricted stock units issued and outstanding 8,591,673 6,940,566 Reserved for future stock awards or option grants 2,217,814 2,434,619 Reserved for employee stock purchase plan 1,218,188 911,138 12,027,675 10,286,323

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Summary of Stock Option Activity	The following table summarizes stock option activity during the three months ended March 31, 2022 (in thousands, except share and per share data): Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2021 6,870,617 $ 12.56 8.0 $ 32,637 Granted 1,481,550 $ 16.01 Exercised ( 100,951 ) $ 14.63 Canceled and forfeited ( 102,954 ) $ 17.24 Outstanding as of March 31, 2022 8,148,262 $ 13.10 8.1 $ 73,027 Vested and exercisable as of March 31, 2022 3,507,360 $ 9.65 7.2 $ 43,567
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: Three Months Ended March 31, 2022 2021 Exercise price $ 15.50 -$ 22.41 $ 18.41 -$ 21.22 Expected term (in years) 6.08 6.08 Expected volatility 81.69 %- 82.32 % 93.24 %- 94.06 % Risk-free interest rate 1.46 %- 2.0 % 0.62 %- 1.34 % Expected dividend yield — —
Summary of RSU Activity	The following table summarizes the activity under the Company's RSUs for the three months ended March 31, 2022: Number of Weighted-Average Grant Date Unvested and Outstanding as of December 31, 2021 69,949 $ 18.57 Granted 382,475 $ 16.11 Vested — $ - Cancelled/Forfeited ( 9,013 ) $ 16.50 Unvested and Outstanding as of March 31, 2022 443,411 16.48
Summary of Stock-based Compensation Reflected in Unaudited Condensed Consolidated Statements of Operations	Total stock-based compensation is reflected in the unaudited condensed consolidated statements of operations as follows (in thousands): Three Months Ended March 31, 2022 2021 Selling, general and administrative $ 3,976 $ 2,542 Research and development 2,585 2,743 Total $ 6,561 $ 5,285

Organization and Description _2

Organization and Description of Business - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)Segment	Dec. 31, 2021USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Date of incorporation	May 2, 2018
Number of operating segments | Segment	1
Accumulated deficit	$ 293,765	$ 257,159
Cash, cash equivalents and investments	239,900
Cash, Unrestricted Cash Equivalents and Investments	$ 139,900

Summary of Significant Accoun_4

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	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 46,272	$ 31,340
Restricted cash equivalents	100,000	100,000
Total cash, cash equivalents, and restricted cash equivalents	$ 146,272	$ 131,340	$ 90,677	$ 142,086

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule Of Finite Lived Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gross carrying value	$ 19,000	$ 19,000
Less accumulated amortization	(519)	(260)
Net carrying value	$ 18,481	$ 18,740

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Estimated Future Amortization Expense Associated with Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
2022 (remaining nine months)	$ 779
2023	1,038
2024	1,038
2025	1,038
2026	1,038
Thereafter	13,550
Net carrying value	$ 18,481	$ 18,740

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Shares of Common Stock Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	8,738,120	7,086,146
Options to Purchase Common Stock and Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	8,591,673	6,940,566
Common Stock Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	89,066	122,464
Employee Stock Purchase Plan Contingently Issuable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	57,381	23,116

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Intangible asset useful lives	18 years
Amortization expense	$ 300	$ 0

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) - Fair Value, Recurring Basis - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financial assets:
Fair value measurements	$ 237,488	$ 258,604
Financial liabilities:
Derivative liability	1,996	1,996
Total financial liabilities	1,996	1,996
Level 1
Financial assets:
Fair value measurements	143,853	128,420
Financial liabilities:
Derivative liability	0	0
Total financial liabilities	0	0
Level 2
Financial assets:
Fair value measurements	93,635	130,184
Financial liabilities:
Derivative liability	0	0
Total financial liabilities	0	0
Level 3
Financial assets:
Fair value measurements	0	0
Financial liabilities:
Derivative liability	1,996	1,996
Total financial liabilities	1,996	1,996
Money Market Fund
Financial assets:
Fair value measurements	143,853	128,420
Money Market Fund | Level 1
Financial assets:
Fair value measurements	143,853	128,420
Money Market Fund | Level 2
Financial assets:
Fair value measurements	0	0
Money Market Fund | Level 3
Financial assets:
Fair value measurements	0	0
Commercial Paper
Financial assets:
Fair value measurements	78,765	115,221
Commercial Paper | Level 1
Financial assets:
Fair value measurements	0	0
Commercial Paper | Level 2
Financial assets:
Fair value measurements	78,765	115,221
Commercial Paper | Level 3
Financial assets:
Fair value measurements	0	0
U.S. Government Bonds
Financial assets:
Fair value measurements	14,870	14,963
U.S. Government Bonds | Level 1
Financial assets:
Fair value measurements	0	0
U.S. Government Bonds | Level 2
Financial assets:
Fair value measurements	14,870	14,963
U.S. Government Bonds | Level 3
Financial assets:
Fair value measurements	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	Mar. 31, 2022	Dec. 31, 2021
Discount Rate
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Discount rate used for valuation to derivative liability	0.157	0.157

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Change in Estimated Fair Value of Company's Derivative Liability Classified as Level 3 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Change in fair value of derivative liability	$ 0	$ (334)
Change in fair value of derivative liability	0	$ 334
Level 3
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	1,996
Ending balance	$ 1,996

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	Mar. 31, 2022	Dec. 31, 2021
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and investments, Amortized cost	$ 237,617	$ 258,640
Cash equivalents and investments, Unrealized loss	(129)	(36)
Cash equivalents and investments, Estimated Fair Value	237,488	258,604
Cash equivalents, Estimated Fair Value	43,852	28,420
Restricted Cash and Cash Equivalents	100,000	100,000
Short-term investments	93,636	125,201
Investments		4,983
Total cash equivalents and investments	237,488	258,604
Money Market Fund
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	143,853	128,420
Cash equivalents, Estimated Fair Value	143,853	128,420
U.S. Government Bonds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	14,999	14,999
Investments, Unrealized Gain	0	0
Investments, Unrealized Loss	(129)	(36)
Investments, Estimated Fair Value	14,870	14,963
Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	78,765	115,221
Investments, Unrealized Gain	0	0
Investments, Unrealized Loss	0	0
Investments, Estimated Fair Value	$ 78,765	$ 115,221

Financial Instruments - Remaini

Financial Instruments - Remaining contractual maturities of available-for-sale debt securities (Details) $ in Thousands	Mar. 31, 2022USD ($)
Financial Instruments, Owned, at Fair Value [Abstract]
Due within one year	$ 93,636
One to two years	0
Debt Securities, Held-to-maturity, Fair Value, Total	$ 93,636

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financial Instruments, Owned, at Fair Value [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
Other-than-temporary impairment losses	$ 0	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Raw material	$ 858	$ 856
Work in progress	553	570
Finished goods	169	87
Total inventory	$ 1,580	$ 1,513

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued clinical trials	$ 8,418	$ 6,732
Accrued professional service fees	4,961	2,458
Accrued contract manufacturing and non-clinical costs	5,079	4,635
Accrued compensation and related benefits	5,600	9,988
Accrued rebates payable	1,654	265
Accrued royalties payable	1,171	345
Accrued collaboration funding	0	6,300
Total accrued expenses	$ 26,883	$ 30,723

Revenue Interest Purchase Agr_3

Revenue Interest Purchase Agreement - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue interest liability		$ 132,940			$ 129,923
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		2.00%
Revenue interest rate percentage shall be reduced, if revenue interest payment percentage greater than or equal to 110% at Tier		2.00%
Revenue interest rate percentage shall be reduced, if revenue interest payment percentage greater than or equal to 110% at Tier 3		0.00%
Required revenue interest payment percentage of cumulative purchaser payments for termination		195.00%
Required repurchase price percentage of cumulative purchaser prior to first anniversary of closing date		120.00%
Required repurchase price percentage of cumulative purchaser payments after first anniversary and prior to third anniversary of closing date		175.00%
Required repurchase price percentage of cumulative purchaser after third anniversary of closing date		195.00%
Purchase agreement amount allocated to debt		$ 49,200
Initial fair value of derivative liability		1,300
Revenue interest liability		132,900			$ 129,900
Debt issuance costs		900
Interest expense		$ 3,800	$ 3,400
Revenue Interest Purchase Agreement | Mulholland SA LLC, | On or Prior to December 31, 2026
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Minimum required revenue interest payment percentage to cumulative purchaser payments to reduce interest rate		110.00%
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
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
Revenue Interest Purchase Agreement | Mulholland SA LLC, | Livmarli
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone and upfront payments received		115,000
Upfront payment received				$ 50,000
Milestone payment received	$ 65,000
Potential milestone payment received upon regulatory approval		35,000
Tier I | Mulholland SA LLC, | Livmarli | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		350,000
Tier 2 | Mulholland SA LLC, | Livmarli | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		350,000
Tier 2 | Mulholland SA LLC, | Livmarli | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		1,100,000
Tier 3 | Mulholland SA LLC, | Livmarli | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual net sales		$ 1,100,000
CSPA | Mulholland SA LLC,
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of shares sold		509,164
Aggregate purchase price		$ 10,000
Net proceeds from transaction		10,000
Purchase agreement amount allocated to common stock issued		$ 10,800

Revenue Interest Purchase Agr_4

Revenue Interest Purchase Agreement - Summary of Revenue Interest Liability (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue interest liability	$ 129,923
Interest expense recognized	3,774
Revenue interest payments	757
Revenue interest liability	$ 132,940

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details)	1 Months Ended		3 Months Ended
	Apr. 30, 2021USD ($)	Nov. 30, 2018USD ($)ProductCandidate$ / sharesshares	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)
Shire | Volixibat
Asset Acquisitions [Line Items]
Milestone payment			$ 0	$ 2,000,000
Shire | Livmarli
Asset Acquisitions [Line Items]
Development or Regulatory Milestones Incurred			0	$ 15,000,000
Shire Agreement | Shire
Asset Acquisitions [Line Items]
Number of product candidates | ProductCandidate		2
Upfront payment		$ 7,500,000
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
Shire Agreement | Shire | Redeemable Common Stock
Asset Acquisitions [Line Items]
Temporary equity, shares issued | shares		1,859,151
Issuance of Series A redeemable convertible preferred stock, net of issuance costs		$ 7,000,000
Shares issued, price per share | $ / shares		$ 3.76
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
Milestones accrued			0
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
Assigned License Agreement | Shire
Asset Acquisitions [Line Items]
Milestones accrued			$ 0
Exclusive Licensing Agreement | Livmarli | CANbridge | Maximum
Asset Acquisitions [Line Items]
Potential regulatory and commercial milestone payment to be received	$ 109,000,000

Collaboration and License Agr_2

Collaboration and License Agreements (Additional Information) (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	Jan. 31, 2022	Jul. 31, 2021	Apr. 30, 2021	Mar. 31, 2022
Vivet Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License and collaboration agreement date			Apr. 30, 2021
Upfront fee			$ 4,200
Final payment on terminating agreement	$ 6,300
Exclusive Licensing Agreement | Livmarli | CANbridge
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received			11,000
Transaction price, adjustments				$ 0
Research and development funding received				400
Achievement of future regulatory and commercial milestones payment	$ 2,000
Exclusive Licensing Agreement | Livmarli | CANbridge | Prepaid Expenses and Other Current Assets [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other research and development receivable				1,200
Exclusive Licensing Agreement | Livmarli | CANbridge | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential regulatory and commercial milestone payment to be received			109,000
Research and development funding received			$ 5,000
Exclusive Licensing Agreement | Livmarli | GC Biopharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received		$ 5,000
Transaction price, adjustments				$ 0
Exclusive Licensing Agreement | Livmarli | GC Biopharma | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Achievement of future regulatory and commercial milestones payment		$ 23,000

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 30, 2019USD ($)ft²	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)	Sep. 30, 2021	Dec. 31, 2021USD ($)	Jan. 31, 2019USD ($)	Jan. 22, 2019ft²
Lessee Lease Description [Line Items]
Area of office space | ft²							5,600
Term of lease							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
Operating lease right-of-use assets		$ 1,468			$ 1,569
Lease liability		$ 2,444
Tenant improvement allowance						$ 400
Weighted-average incremental borrowing rate		8.00%
Weighted-average remaining lease term		2 years 10 months 24 days
Rent expense		$ 200	$ 200
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	Mar. 31, 2022USD ($)
Leases [Abstract]
2022 (remaining nine months)	$ 670
2023	918
2024	926
2025	230
Total undiscounted lease payments	2,744
Less: imputed interest	(300)
Total lease liability	$ 2,444

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2022	Jan. 31, 2021	Dec. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Aug. 31, 2020
Class Of Stock [Line Items]
Maximum amount of sale covered in shelf registration statement							$ 300
Common stock aggregate offering price, remaining	$ 50.4			$ 50.4
SVB Leerink LLC
Class Of Stock [Line Items]
Maximum amount of offering issuance and sale covered in sales agreement							$ 75
Common Stock
Class Of Stock [Line Items]
Number of shares issued				995,897	375,654
Number of shares subject to repurchase	89,066			89,066		122,464
Common Stock | Sales Agreement
Class Of Stock [Line Items]
Number of shares issued	1,301,866		3,750,000	995,897
Shares issued, public offering price per share	$ 18.06		$ 20	$ 18.06
Proceeds from issuance of shares	$ 23.7		$ 70	$ 17.4
Gross proceeds from issuance of common stock	$ 24.6			$ 18
Common Stock | Sales Agreement | Weighted Average
Class Of Stock [Line Items]
Shares issued, public offering price per share	$ 18.88			$ 18.88
Underwritten Public Offerings | Common Stock | Sales Agreement | Maximum
Class Of Stock [Line Items]
Number of shares issued			562,500
Public Offering
Class Of Stock [Line Items]
Proceeds from issuance of shares		$ 7.1
Public Offering | Common Stock
Class Of Stock [Line Items]
Shares issued, public offering price per share		$ 20
Number of shares purchased		375,654

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Common Stock Reserved for Issuance (Details) - shares	Mar. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock reserved for issuance	12,027,675	10,286,323
Stock options and restricted stock units issued and outstanding
Class Of Stock [Line Items]
Common stock reserved for issuance	8,591,673	6,940,566
Reserved for Future Stock Awards or Option Grants
Class Of Stock [Line Items]
Common stock reserved for issuance	2,217,814	2,434,619
Reserved for Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for issuance	1,218,188	911,138

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Jul. 31, 2019	Nov. 30, 2018	Mar. 31, 2022	Mar. 31, 2021	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			12,027,675		10,286,323
Stock-based compensation expense			$ 6,561	$ 5,285
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, Intrinsic value of options exercised			800	$ 200
Total unrecognized stock-based compensation related to unvested stock option awards granted			$ 50,800
Unrecognized stock-based compensation related to unvested stock, expected to recognize over weighted-average period			2 years 9 months 18 days
Expected dividend yield			0.00%	0.00%
Weighted-average grant-date fair value			$ 11.27	$ 14.55
Restricted Stock
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			7 months 6 days
Vested			33,398	33,396
Total unrecognized compensation expense related to unvested restricted stock			$ 300
Restricted Stock | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		$ 2.94
Restricted Stock | Common Stock | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued for services		562,500
Vesting period		4 years
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 March 31, 2022, 1,218,738 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. 1, 2020
Shares of common stock ending date	Jan. 1, 2029
Percentage of annual increase in common stock available for issuance	5.00%
Number of common stock for future issuance			1,218,738
2020 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock for future issuance			999,076				750,000
Number of additional common stock for future issuance					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			A total of 500,000 shares of common stock were approved to be initially reserved for issuance under the ESPP. In addition, the 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. There were no shares issued under the ESPP for the three months ended March 31, 2022. As of March 31, 2022, the Company had 1,218,188 shares available for future issuance under the ESPP.
Shares of common stock expiration term	10 years
Shares of common stock beginning date	Jan. 1, 2020
Shares of common stock ending date	Jan. 1, 2029
Percentage of annual increase in common stock available for issuance	1.00%
Number of common stock approved and reserved for issuance			1,218,188
Stock issued for services	500,000		0
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			$ 200	$ 200

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Options, Outstanding
Number of shares, Outstanding, Beginning balance	6,870,617
Number of shares, Granted	1,481,550
Number of shares, Exercised	(100,951)
Number of shares, Canceled and forfeited	(102,954)
Number of shares, Outstanding, Ending balance	8,148,262	6,870,617
Number of shares, Vested and exercisable	3,507,360
Weighted-average exercise price, Outstanding
Weighted-average exercise price, Outstanding, Beginning balance	$ 12.56
Weighted-average exercise price, Granted	16.01
Weighted-average exercise price, Exercised	14.63
Weighted-average exercise price, Canceled and forfeited	17.24
Weighted-average exercise price, Outstanding, Ending balance	13.10	$ 12.56
Weighted-average exercise price, Vested and exercisable	$ 9.65
Share-based Payment Award, Options, Additional Disclosures
Weighted-average remaining contractual life, Outstanding	8 years 1 month 6 days	8 years
Weighted-average remaining contractual life, Vested and exercisable	7 years 2 months 12 days
Aggregate intrinsic value, Outstanding	$ 73,027	$ 32,637
Aggregate intrinsic value, Vested and exercisable	$ 43,567

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards Granted (Details) - Stock Options - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price, minimum	$ 15.50	$ 18.41
Exercise price, maximum	$ 22.41	$ 21.22
Expected term (in years)	6 years 29 days	6 years 29 days
Expected volatility, minimum	81.69%	93.24%
Expected volatility, maximum	82.32%	94.06%
Risk-free interest rate, minimum	1.46%	0.62%
Risk-free interest rate, maximum	2.00%	1.34%
Expected dividend yield	0.00%	0.00%

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - RSUs - $ / shares	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested and Outstanding as of December 31, 2021	443,411	69,949
Granted	382,475
Vested	0
Number of shares, Canceled and forfeited	(9,013)
Unvested and Outstanding as of March 31, 2022	443,411	69,949
Weighted-average exercise price, Granted	$ 16.11
Weighted-average exercise price, Vested	0
Weighted-average exercise price, Canceled and forfeited	16.50
Weighted-average exercise price, Vested and exercisable	$ 16.48	$ 18.57

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock-based Compensation Reflected in Unaudited Condensed Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 6,561	$ 5,285
Selling, General and Administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	3,976	2,542
Research and Development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 2,585	$ 2,743