Mirum Pharmaceuticals (MIRM) 10-Q 7 May 20 2020 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 01, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
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		25,389,987
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common stock
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 72,035	$ 11,970
Short-term investments	87,496	104,690
Prepaid expenses and other current assets	2,905	2,703
Total current assets	162,436	119,363
Long-term investments	6,530	23,292
Property and equipment, net	1,397	1,372
Operating lease right-of-use assets	2,280	2,361
Other assets	160	324
Total assets	172,803	146,712
Current liabilities:
Accounts payable	3,265	3,351
Accrued expenses	9,772	9,328
Operating lease liabilities	511	397
Total current liabilities	13,548	13,076
Operating lease liabilities, noncurrent	3,103	3,251
Other liabilities	34	36
Total liabilities	16,685	16,363
Commitments and contingencies	0
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of March 31, 2020 and December 31, 2019, respectively; zero shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively; and liquidation value of $0 as of March 31, 2020 and December 31, 2019, respectively	0
Common stock, $0.0001 par value; 200,000,000 shares authorized as of March 31, 2020 and December 31, 2019, respectively; 25,389,987 shares issued and 25,033,736 shares outstanding, excluding 356,251 shares subject to repurchase as of March 31, 2020; 22,989,987 shares issued and 22,600,338 shares outstanding, excluding 389,649 shares subject to repurchase as of December 31, 2019	3	2
Additional paid-in capital	247,350	200,119
Accumulated deficit	(91,211)	(69,901)
Accumulated other comprehensive income (loss)	(24)	129
Total stockholders’ equity	156,118	130,349
Total liabilities and stockholders’ equity	$ 172,803	$ 146,712

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
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
Preferred stock, liquidation preference	$ 0	$ 0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	25,389,987	22,989,987
Common stock, shares, outstanding	25,033,736	22,600,338
Common stock, subject to repurchase	356,251	389,649

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 17,340	$ 4,863
General and administrative	4,692	1,321
Total operating expenses	22,032	6,184
Loss from operations	(22,032)	(6,184)
Other income (expense):
Interest income	749	232
Other income (expense), net	(23)	(5)
Net loss before provision for income taxes	(21,306)	(5,957)
Provision for income taxes	4	0
Net loss	$ (21,310)	$ (5,957)
Net loss per share, basic and diluted	$ (0.86)	$ (2.37)
Weighted-average shares of common stock outstanding, basic and diluted	24,704,651	2,517,743

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (21,310)	$ (5,957)
Other comprehensive loss:
Unrealized loss on available-for-sale investments	(149)	0
Cumulative translation adjustments	(4)	0
Comprehensive loss	$ (21,463)	$ (5,957)

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Redeemable Convertible Preferred Stock, Redeemable Common Stock and Stockholders' Deficit (Unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Redeemable Common Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income(Loss)
Balance at Dec. 31, 2018		$ 59,849	$ 6,990
Balance, Shares at Dec. 31, 2018		59,908,284	1,859,151
Balance at Dec. 31, 2018	$ (17,313)			$ 1	$ 34	$ (17,348)
Balance, Shares at Dec. 31, 2018				636,719
Restricted common stock vested in the period, Shares				35,156
Stock-based compensation	218				218
Net loss	(5,957)					(5,957)
Balance at Mar. 31, 2019		$ 59,849	$ 6,990
Balance, Shares at Mar. 31, 2019		59,908,284	1,859,151
Balance at Mar. 31, 2019	(23,052)			$ 1	252	(23,305)
Balance, Shares at Mar. 31, 2019				671,875
Balance at Dec. 31, 2019	130,349			$ 2	200,119	(69,901)	$ 129
Balance, Shares at Dec. 31, 2019				22,600,338
Issuance of common stock	44,659			$ 1	44,658
Issuance of common stock, Shares				2,400,000
Restricted common stock vested in the period, Shares				33,398
Stock-based compensation	2,573				2,573
Net loss	(21,310)					(21,310)
Other comprehensive loss	(153)						(153)
Balance at Mar. 31, 2020	$ 156,118			$ 3	$ 247,350	$ (91,211)	$ (24)
Balance, Shares at Mar. 31, 2020				25,033,736

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Redeemable Convertible Preferred Stock, Redeemable Common Stock and Stockholders' Deficit (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Common Stock
Issuance of common stock upon initial public offering, issuance costs	$ 3,342

Condensed Consolidated Statem_5

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities
Net loss	$ (21,310)	$ (5,957)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation	2,573	218
Depreciation and amortization	73	0
Amortization of operating lease right-of-use assets	83	27
Net accretion of discounts on investments	(52)	0
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(158)	(251)
Operating lease right-of-use assets	0	(32)
Other assets	0	(125)
Accounts payable, accrued expenses and other liabilities	476	3,677
Operating lease liabilities	(36)	17
Net cash used in operating activities	(18,351)	(2,426)
Investing activities
Proceeds from maturities of investments	29,500	0
Proceeds from paydowns of investments	4,359	0
Purchase of property and equipment	(98)	(44)
Net cash provided by (used in) investing activities	33,761	(44)
Financing activities
Proceeds from issuance of common stock in public offering, net of issuance costs	44,659	0
Net cash provided by financing activities	44,659	0
Effect of exchange rate on cash and cash equivalents	(4)	0
Net increase (decrease) in cash and cash equivalents	60,065	(2,470)
Cash and cash equivalents at beginning of period	11,970	51,963
Cash and cash equivalents at end of period	72,035	49,493
Supplemental disclosure of cash flow information:
Operating lease right-of-use asset obtained in exchange for operating lease liability	0	1,268
Landlord paid tenant improvements	0	409
Deferred initial public offering costs in accounts payable	$ 0	$ 302

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	1. 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 development and commercialization of a late-stage pipeline of novel therapies for debilitating liver diseases. The Company’s pipeline consists of two clinical-stage product candidates, maralixibat and volixibat, with mechanisms of action that have potential utility across a wide range of orphan liver diseases. The Company commenced significant operations in November 2018. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, Mirum Pharmaceuticals AG. All intercompany balances and transactions among the consolidated entities have been eliminated in consolidation. Reverse Stock Split On July 3, 2019, the Company effected a 1-for-8 reverse stock split of its common stock. The par value and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split. The reverse stock split resulted in an adjustment to the conversion price of the Company’s Series A redeemable convertible preferred stock (the “Series A Preferred Stock”) to reflect a proportional decrease in the number of shares of common stock to be issued upon conversion. The accompanying consolidated financial statements and notes to the consolidated financial statements give retroactive effect to the reverse stock split for all periods presented. Follow-on Public Offering On January 13, 2020, the Company completed a follow-on public offering of its common stock, pursuant to which the Company sold 2,400,000 shares of common stock at a price of $20.00 per share, resulting in net proceeds of $44.7 million after deducting underwriting discounts, commissions and offering expenses. 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, 2020, the Company had an accumulated deficit of $91.2 million and cash, cash equivalents and investments of $166.1 million, which is available to fund future operations. The Company believes that its cash, cash equivalents and investments as of March 31, 2020 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. As such, 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
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 unaudited condensed consolidated balance sheet as of December 31, 2019 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. 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, 2019, as filed with the SEC on March 12, 2020. 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. The most significant estimates in the Company’s unaudited condensed consolidated financial statements relate to accrued research and development expenses, the valuation of investments, the valuation of common stock, equity awards and the valuation allowance of deferred tax assets resulting from net operating losses. 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. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including clinical trials delays and costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international markets. There were no significant estimates contained in the preparation of the Company’s consolidated financial statements or impacts to the Company’s consolidated financial statements for the three months ended March 31, 2020 that were directly a result of the COVID-19 pandemic. Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2020, as compared to the significant accounting policies described in Note 2 of the “Notes to Consolidated Financial Statements” in the Company’s audited financial statements included 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 and common stock options because their effect would be anti-dilutive due to the Company’s net loss. Since the Company had 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, 2020 2019 Options to purchase common stock 4,436,862 3,366,812 Common stock subject to repurchase 356,251 389,649 Total 4,793,113 3,756,461 Recently Adopted Accounting Pronouncements On January 1, 2020, the Company adopted Accounting Standards Update (“ASU”) No. 2018-13, Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement (Topic 820) Other recent accounting pronouncements issued by the Financial Accounting Standards Board (“FASB”) (including its Emerging Issues Task Force), the American Institute of Certified Public Accountants, and the SEC did not, or are not believed by management to, have a material impact on the Company’s present or future consolidated financial position, results of operations or cash flows. 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 Codification Improvements to Topic 326, Financial Instruments - Credit Losses Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Derivatives and Hedging (Topic 815), and Financial Instruments (Topic 842), is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019 for public business entities, excluding smaller reporting companies. Early adoption is permitted. In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (Topic 740) . The guidance eliminates certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. This guidance also includes guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. ASU 2019-12 is effective for annual and interim periods in fiscal years beginning after December 15, 2020. Early adoption is permitted. The Company is currently evaluating the impact this change will have on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
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 as of March 31, 2020 and December 31, 2019 are presented in the following table (in thousands): March 31, 2020 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 70,659 $ — $ — $ 70,659 Corporate debt securities — 39,451 — 39,451 Commercial paper — 15,145 — 15,145 U.S. government bonds — 15,063 — 15,063 Asset backed securities — 24,367 — 24,367 Total $ 70,659 $ 94,026 $ — $ 164,685 December 31, 2019 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 10,621 $ — $ — $ 10,621 Corporate debt securities — 41,668 — 41,668 Commercial paper — 35,016 — 35,016 U.S. government bonds — 22,511 — 22,511 Asset-backed securities — 28,787 — 28,787 Total $ 10,621 $ 127,982 $ — $ 138,603 The carrying amounts of certain financial instruments such as cash and cash equivalents, accounts receivable, prepaid expenses, other current assets, accounts payable, accrued expenses, and other current liabilities as of March 31, 2020 and December 31, 2019 approximate their related fair values due to the short-term maturities of these instruments. The fair value of certain financial instruments was measured and classified within Level 1 of the fair value hierarchy based on quoted prices.

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2020
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, 2020 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Cash equivalents and investments: Money market fund $ 70,659 $ — $ — $ 70,659 Corporate debt securities 39,464 28 (41 ) 39,451 Commercial paper 15,145 — — 15,145 U.S. government bonds 15,000 63 — 15,063 Asset back securities 24,410 11 (54 ) 24,367 Total cash equivalents and investments $ 164,678 $ 102 $ (95 ) $ 164,685 Classified as: Cash equivalents $ 70,659 Short-term investments 87,496 Long-term investments 6,530 Total cash equivalents and investments $ 164,685 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Cash equivalents and investments: Money market fund $ 10,621 $ — $ — $ 10,621 Corporate debt securities 41,556 113 (1 ) 41,668 Commercial paper 35,016 — — 35,016 U.S. government bonds 22,492 19 — 22,511 Asset-backed securities 28,762 25 — 28,787 Total cash equivalents and investments $ 138,447 $ 157 $ (1 ) $ 138,603 Classified as: Cash equivalents $ 10,621 Short-term investments 104,690 Long-term investments 23,292 Total cash equivalents and investments $ 138,603 As of March 31, 2020, the remaining contractual maturities of available-for-sale debt securities were as follows (in thousands): Estimated Fair Value Due within one year $ 85,863 One to two years 8,163 Total $ 94,026 During the three months ended March 31, 2020, there have been no significant realized gains or losses on available-for-sale investments. During the three months ended March 31, 2020, the Company did not recognize any other-than-temporary impairment losses

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2020
Payables And Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consists of the following (in thousands): March 31, December 31, 2020 2019 Accrued clinical trials $ 4,539 $ 4,795 Accrued professional service fees 812 777 Accrued contract manufacturing and non-clinical costs 3,219 1,540 Accrued compensation and related benefits 1,202 2,216 Total accrued expenses $ 9,772 $ 9,328

Asset Acquisitions

Asset Acquisitions	3 Months Ended
	Mar. 31, 2020
Asset Acquisitions [Abstract]
Asset Acquisitions	6. Asset Acquisitions Assignment and License Agreement with Shire International GmbH On November 5, 2018, the Company entered into an Assignment and License Agreement (the “Shire Agreement”) with Shire International GmbH (“Shire”). 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, maralixibat 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. In consideration for the rights granted to the Company under the Shire Agreement, the Company made an upfront payment to Shire on November 5, 2018 of $7.5 million and issued Shire 1,859,151 shares of its redeemable common stock with an estimated fair value of $7.0 million, or $3.76 per share. The fair value of the shares was determined using an option pricing model with key assumptions as of the date of issuance including the probabilities of liquidity scenarios, enterprise value, time to liquidity, risk-free interest rates, volatility and discount for lack of marketability. The Company accounted for the transaction as an asset acquisition as substantially all of the fair value of the gross assets acquired were concentrated in a group of similar identifiable assets thus satisfying the requirements of the screen test in ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business The Company is also obligated to pay Shire up to an aggregate of $109.5 million upon the achievement of certain clinical development and regulatory milestones for maralixibat in certain indications and an additional $25.0 million upon regulatory approval of maralixibat 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 maralixibat 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. In July 2019, the Company achieved a development milestone related to the initiation of the Phase 3 MARCH-PFIC clinical trial and made a $2.5 million payment to Shire. As of March 31, 2020, no additional milestones had been accrued as there were no other potential milestones yet considered probable. In January 2019, the Company also entered into a Transition Services Agreement (“TSA”) with Shire, which covered services provided by Shire to transfer the research and development activities and the related know-how from Shire to the Company, including continuation of work on any existing clinical trials and manufacturing activities until fully transferred. All transition services were completed and all pass-through costs were settled as of June 30, 2019. As such, for the three months ended March 31, 2020, there were no expenses for Shire provided services or pass-through costs recorded. For the three months ended March 31, 2019, the Company recorded $0.3 million for services provided by Shire under the TSA and $0.1 million for pass-through costs related to continuation of work on existing clinical trials and manufacturing activities. 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. In July 2019, the Company achieved a development milestone related to the initiation of the Phase 3 MARCH-PFIC clinical trial and made a $0.5 million payment to Satiogen. As of March 31, 2020, no additional milestones had been accrued as there were no other 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. As of March 31, 2020, no milestones had been accrued as there were no potential milestones yet considered probable.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Stockholders' Equity (Deficit)	7. Stockholders’ Equity (Deficit) In connection with the Company’s initial public offering in July 2019, all of the outstanding shares of the Company’s Series A Preferred Stock automatically converted into 14,969,118 shares of common stock and the 1,859,151 shares of the Company’s redeemable common stock classified in mezzanine equity were reclassified to permanent equity due to the expiration of the deemed redemption feature associated with the stock. Common Stock In August and October 2018, the Company issued 1,187,500 shares of common stock as founder shares for services rendered to the Company, valued at $0.0001 per share for consideration of approximately $950. On November 5, 2018, in connection with the issuance of the Series A Preferred Stock, vesting conditions were placed on 562,500 previously issued founder shares. These shares vest over 4 years and are subject to repurchase by the Company in the event of termination of services. Shares subject to repurchase are not deemed, for accounting purposes, to be outstanding until those shares vest. In April 2019, the Company repurchased 25,782 shares of the common stock from a former employee in connection with termination of employment. As of March 31, 2020 and December 31, 2019, 356,251 and 389,649 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. Each share of common stock is entitled to one voting right. Common stockholders are entitled to dividends when funds are legally available and declared by the Company’s board of directors. Common Stock Reserved for Issuance Common stock reserved for issuance is as follows: As of March 31, As of December 31, 2020 2019 Stock options issued and outstanding 4,436,862 3,366,812 Reserved for future stock awards or option grants 1,941,892 1,112,443 Reserved for employee stock purchase plan 729,899 500,000 7,108,653 4,979,255

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation Equity Incentive Plans On November 5, 2018, the Company adopted the 2018 Equity Incentive Plan (the “2018 Plan”) which permits the granting of stock awards and incentive and nonstatutory stock options to employees, directors and consultants of the Company. In July 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan became effective on July 17, 2019. Under the 2019 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other stock or cash-based awards to individuals who are then employees, officers, directors or consultants of the Company. A total of 1,401,443 shares of common stock were approved to be initially reserved for issuance under the 2019 Plan, including 101,443 shares that remained available for issuance under the 2018 Plan as of July 17, 2019. 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, 2020, 1,191,892 shares of common stock were available for issuance under the 2019 Plan. On March 18, 2020, the compensation committee of the Company’s board of directors approved and adopted the 2020 Inducement Plan (the “2020 Inducement Plan”). Under the 2020 Inducement Plan, the Company may grant nonstatutory stock options, stock appreciation rights, restricted stock and restricted stock units to new employees entering into employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4) . The 2020 Inducement Plan authorized 750,000 shares of the Company’s common stock for future issuance. As of March 31, 2020, no awards had been granted under the 2020 Inducement Plan. Stock Options 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, 2020 2019 Exercise price $10.40 - $24.52 $ 2.94 Expected term (in years) 5.50 - 6.08 6.25 Expected volatility 77.07% - 88.11% 74.53% Risk-free interest rate 0.51% - 1.73% 2.46% Expected dividend yield — — Grant date fair value of options granted $7.38 - $16.59 $ 4.35 The following table summarizes stock option activity during the three months ended March 31, 2020 (in thousands, except share and per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value Outstanding as of December 31, 2019 3,366,812 $ 5.14 9.3 $ 65,235 Granted 1,115,300 $ 18.68 9.8 Canceled and forfeited (45,250 ) $ 10.28 9.4 Outstanding as of March 31, 2020 4,436,862 $ 8.50 9.3 $ 29,809 Vested and exercisable as of March 31, 2020 499,844 $ 3.35 9.0 $ 5,390 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. As of March 31, 2020, the total unrecognized stock-based compensation related to unvested stock option awards granted was $33.4 million, which the Company expects to recognize over a weighted-average period of approximately 3.2 years. Restricted Stock On November 5, 2018, in connection with the issuance of the 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 total compensation cost resulting from the modification was $1.7 million. The modified shares have a four-year vesting period and a measurement date fair value of $2.936 per share. For the three months ended March 31, 2020 and 2019, 33,398 and 35,156 shares vested, respectively. As of March 31, 2020, the total unrecognized compensation expense related to unvested restricted stock was $1.0 million expected to be recognized over a weighted-average period of approximately 2.7 years. Stock-based compensation expense is reflected in the unaudited condensed consolidated statements of operations (in thousands): Three Months Ended March 31, Three Months Ended March 31, 2020 2019 General and administrative $ 1,532 $ 147 Research and development 1,041 71 Total $ 2,573 $ 218 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 (the “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 lessor 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. As of March 31, 2020, the ESPP was not activated and there were 729,899 shares available for future issuance.

Leases

Leases	3 Months Ended
	Mar. 31, 2020
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 “Lease”). Pursuant to the 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 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 Lease to extend the term 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 Lease, as amended, the Company expanded the office space by 5,555 square feet for a five-year term expiring in March 2025. The Company accounted for this expanded space as a separate contract as there were material additional rights of use that were not included under the terms of the initial Lease. The Lease, as amended, contained a tenant improvement allowance of $0.8 million in connection with the expanded space, which has been recorded as leasehold improvements on the accompanying consolidated balance sheet 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%. As of March 31, 2020, the Company recorded an aggregate ROU asset of $2.3 million and an aggregate lease liability of $3.6 million in the accompanying consolidated balance sheet. The weighted-average remaining lease term is 4.9 years. As of March 31, 2020, undiscounted future minimum payments under the Company’s operating leases are as follows: Year Ending December 31, Undiscounted Rent Payments 2020 (remaining nine months) $ 567 2021 865 2022 890 2023 918 2024 928 2025 230 Total undiscounted lease payments 4,398 Less: imputed interest (784 ) Total lease liability $ 3,614 Rent expense was $0.2 million and $0.1 million for the three months ended March 31, 2020 and 2019, respectively. Variable lease payments for operating expenses were immaterial for the three months ended March 31, 2020 and 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
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 unaudited condensed consolidated balance sheet as of December 31, 2019 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. 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, 2019, as filed with the SEC on March 12, 2020.
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. The most significant estimates in the Company’s unaudited condensed consolidated financial statements relate to accrued research and development expenses, the valuation of investments, the valuation of common stock, equity awards and the valuation allowance of deferred tax assets resulting from net operating losses. 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. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including clinical trials delays and costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain it or treat COVID-19, as well as the economic impact on local, regional, national and international markets. There were no significant estimates contained in the preparation of the Company’s consolidated financial statements or impacts to the Company’s consolidated financial statements for the three months ended March 31, 2020 that were directly a result of the COVID-19 pandemic.
Significant Accounting Policies	Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2020, as compared to the significant accounting policies described in Note 2 of the “Notes to Consolidated Financial Statements” in the Company’s audited financial statements included
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 and common stock options because their effect would be anti-dilutive due to the Company’s net loss. Since the Company had 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, 2020 2019 Options to purchase common stock 4,436,862 3,366,812 Common stock subject to repurchase 356,251 389,649 Total 4,793,113 3,756,461
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements On January 1, 2020, the Company adopted Accounting Standards Update (“ASU”) No. 2018-13, Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement (Topic 820) Other recent accounting pronouncements issued by the Financial Accounting Standards Board (“FASB”) (including its Emerging Issues Task Force), the American Institute of Certified Public Accountants, and the SEC did not, or are not believed by management to, have a material impact on the Company’s present or future consolidated financial position, results of operations or cash flows.
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 Codification Improvements to Topic 326, Financial Instruments - Credit Losses Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Derivatives and Hedging (Topic 815), and Financial Instruments (Topic 842), is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019 for public business entities, excluding smaller reporting companies. Early adoption is permitted. In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (Topic 740) . The guidance eliminates certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. This guidance also includes guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. ASU 2019-12 is effective for annual and interim periods in fiscal years beginning after December 15, 2020. Early adoption is permitted. The Company is currently evaluating the impact this change will have on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Summary of Outstanding Potentially Dilutive Shares 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, 2020 2019 Options to purchase common stock 4,436,862 3,366,812 Common stock subject to repurchase 356,251 389,649 Total 4,793,113 3,756,461

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
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 as of March 31, 2020 and December 31, 2019 are presented in the following table (in thousands): March 31, 2020 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 70,659 $ — $ — $ 70,659 Corporate debt securities — 39,451 — 39,451 Commercial paper — 15,145 — 15,145 U.S. government bonds — 15,063 — 15,063 Asset backed securities — 24,367 — 24,367 Total $ 70,659 $ 94,026 $ — $ 164,685 December 31, 2019 Level 1 Level 2 Level 3 Total Financial assets: Money market fund $ 10,621 $ — $ — $ 10,621 Corporate debt securities — 41,668 — 41,668 Commercial paper — 35,016 — 35,016 U.S. government bonds — 22,511 — 22,511 Asset-backed securities — 28,787 — 28,787 Total $ 10,621 $ 127,982 $ — $ 138,603

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Cash equivalents and investments: Money market fund $ 70,659 $ — $ — $ 70,659 Corporate debt securities 39,464 28 (41 ) 39,451 Commercial paper 15,145 — — 15,145 U.S. government bonds 15,000 63 — 15,063 Asset back securities 24,410 11 (54 ) 24,367 Total cash equivalents and investments $ 164,678 $ 102 $ (95 ) $ 164,685 Classified as: Cash equivalents $ 70,659 Short-term investments 87,496 Long-term investments 6,530 Total cash equivalents and investments $ 164,685 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Cash equivalents and investments: Money market fund $ 10,621 $ — $ — $ 10,621 Corporate debt securities 41,556 113 (1 ) 41,668 Commercial paper 35,016 — — 35,016 U.S. government bonds 22,492 19 — 22,511 Asset-backed securities 28,762 25 — 28,787 Total cash equivalents and investments $ 138,447 $ 157 $ (1 ) $ 138,603 Classified as: Cash equivalents $ 10,621 Short-term investments 104,690 Long-term investments 23,292 Total cash equivalents and investments $ 138,603
Summary of Remaining Contractual Maturities of Available-for-sale Debt Securities	As of March 31, 2020, the remaining contractual maturities of available-for-sale debt securities were as follows (in thousands): Estimated Fair Value Due within one year $ 85,863 One to two years 8,163 Total $ 94,026

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2020
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consists of the following (in thousands): March 31, December 31, 2020 2019 Accrued clinical trials $ 4,539 $ 4,795 Accrued professional service fees 812 777 Accrued contract manufacturing and non-clinical costs 3,219 1,540 Accrued compensation and related benefits 1,202 2,216 Total accrued expenses $ 9,772 $ 9,328

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	3 Months Ended
	Mar. 31, 2020
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, 2020 2019 Stock options issued and outstanding 4,436,862 3,366,812 Reserved for future stock awards or option grants 1,941,892 1,112,443 Reserved for employee stock purchase plan 729,899 500,000 7,108,653 4,979,255

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
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, 2020 2019 Exercise price $10.40 - $24.52 $ 2.94 Expected term (in years) 5.50 - 6.08 6.25 Expected volatility 77.07% - 88.11% 74.53% Risk-free interest rate 0.51% - 1.73% 2.46% Expected dividend yield — — Grant date fair value of options granted $7.38 - $16.59 $ 4.35
Summary of Stock Option Activity	The following table summarizes stock option activity during the three months ended March 31, 2020 (in thousands, except share and per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in Years) Aggregate Intrinsic Value Outstanding as of December 31, 2019 3,366,812 $ 5.14 9.3 $ 65,235 Granted 1,115,300 $ 18.68 9.8 Canceled and forfeited (45,250 ) $ 10.28 9.4 Outstanding as of March 31, 2020 4,436,862 $ 8.50 9.3 $ 29,809 Vested and exercisable as of March 31, 2020 499,844 $ 3.35 9.0 $ 5,390
Summary of Stock-based Compensation Expense Reflected in Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss	Stock-based compensation expense is reflected in the unaudited condensed consolidated statements of operations (in thousands): Three Months Ended March 31, Three Months Ended March 31, 2020 2019 General and administrative $ 1,532 $ 147 Research and development 1,041 71 Total $ 2,573 $ 218

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Schedule of Undiscounted Future Minimum Payments under Operating Leases	As of March 31, 2020, undiscounted future minimum payments under the Company’s operating leases are as follows: Year Ending December 31, Undiscounted Rent Payments 2020 (remaining nine months) $ 567 2021 865 2022 890 2023 918 2024 928 2025 230 Total undiscounted lease payments 4,398 Less: imputed interest (784 ) Total lease liability $ 3,614

Description of Business - Addit

Description of Business - Additional Information (Details) $ / shares in Units, $ in Thousands	Jan. 13, 2020USD ($)$ / sharesshares	Jul. 03, 2019	Mar. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)
Organization And Basis Of Presentation [Line Items]
Date of incorporation			May 2, 2018
Reverse stock split ratio		0.125
Proceeds from issuance of shares			$ 44,659	$ 0
Accumulated deficit			91,211		$ 69,901
Cash, cash equivalents and investments			$ 166,100
Common Stock
Organization And Basis Of Presentation [Line Items]
Number of shares issued | shares			2,400,000
Follow-on Public Offering
Organization And Basis Of Presentation [Line Items]
Proceeds from issuance of shares	$ 44,700
Follow-on Public Offering | Common Stock
Organization And Basis Of Presentation [Line Items]
Number of shares issued | shares	2,400,000
Shares issued, price per share | $ / shares	$ 20

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	4,793,113	3,756,461
Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	4,436,862	3,366,812
Common Stock Subject to Repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares of stock	356,251	389,649

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, 2020	Dec. 31, 2019
Financial assets:
Fair value measurements	$ 164,685	$ 138,603
Level 1
Financial assets:
Fair value measurements	70,659	10,621
Level 2
Financial assets:
Fair value measurements	94,026	127,982
Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	0	0
Money Market Fund
Financial assets:
Fair value measurements	70,659	10,621
Money Market Fund | Level 1
Financial assets:
Fair value measurements	70,659	10,621
Money Market Fund | Level 2
Financial assets:
Fair value measurements	0	0
Money Market Fund | Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	0	0
Corporate Debt Securities
Financial assets:
Fair value measurements	39,451	41,668
Corporate Debt Securities | Level 1
Financial assets:
Fair value measurements	0	0
Corporate Debt Securities | Level 2
Financial assets:
Fair value measurements	39,451	41,668
Corporate Debt Securities | Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	0	0
Commercial Paper
Financial assets:
Fair value measurements	15,145	35,016
Commercial Paper | Level 1
Financial assets:
Fair value measurements	0	0
Commercial Paper | Level 2
Financial assets:
Fair value measurements	15,145	35,016
Commercial Paper | Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	0	0
U.S. Government Bonds
Financial assets:
Fair value measurements	15,063	22,511
U.S. Government Bonds | Level 1
Financial assets:
Fair value measurements	0	0
U.S. Government Bonds | Level 2
Financial assets:
Fair value measurements	15,063	22,511
U.S. Government Bonds | Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	0	0
Asset Backed Securities
Financial assets:
Fair value measurements	24,367	28,787
Asset Backed Securities | Level 1
Financial assets:
Fair value measurements	0	0
Asset Backed Securities | Level 2
Financial assets:
Fair value measurements	24,367	28,787
Asset Backed Securities | Fair Value, Inputs, Level 3
Financial assets:
Fair value measurements	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Fair Value and Amortized Cost of Cash Equivalents and Available-for-sale Investments by Major Security Type (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents and investments, Amortized cost	$ 164,678	$ 138,447
Cash equivalents and investments, Unrealized gain	102	157
Cash equivalents and investments, Unrealized loss	(95)	(1)
Cash equivalents and investments, Estimated Fair Value	164,685	138,603
Cash equivalents, Estimated Fair Value	70,659	10,621
Investments, Estimated Fair Value	94,026
Short-term investments	87,496	104,690
Long-term investments	6,530	23,292
Money Market Fund
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents, Amortized Cost	70,659	10,621
Cash equivalents, Estimated Fair Value	70,659	10,621
Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	39,464	41,556
Investments, Unrealized Gain	28	113
Investments, Unrealized Loss	(41)	(1)
Investments, Estimated Fair Value	39,451	41,668
Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	15,145	35,016
Investments, Unrealized Gain	0	0
Investments, Unrealized Loss	0	0
Investments, Estimated Fair Value	15,145	35,016
U.S. Government Bonds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	15,000	22,492
Investments, Unrealized Gain	63	19
Investments, Unrealized Loss	0	0
Investments, Estimated Fair Value	15,063	22,511
Asset Backed Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments, Amortized Cost	24,410	28,762
Investments, Unrealized Gain	11	25
Investments, Unrealized Loss	(54)	0
Investments, Estimated Fair Value	$ 24,367	$ 28,787

Financial Instruments - Summa_2

Financial Instruments - Summary of Remaining Contractual Maturities of Available-for-sale Debt Securities (Details) $ in Thousands	Mar. 31, 2020USD ($)
Fair Value Disclosures [Abstract]
Due within one year	$ 85,863
One to two years	8,163
Total	$ 94,026

Financial Instruments - Additio

Financial Instruments - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020USD ($)
Financial Instruments Owned At Fair Value [Abstract]
Realized gains or losses on available-for-sale investments	$ 0
Other-than-temporary impairment losses	$ 0

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued clinical trials	$ 4,539	$ 4,795
Accrued professional service fees	812	777
Accrued contract manufacturing and non-clinical costs	3,219	1,540
Accrued compensation and related benefits	1,202	2,216
Total accrued expenses	$ 9,772	$ 9,328

Asset Acquisitions - Additional

Asset Acquisitions - Additional Information (Details)	Nov. 05, 2018USD ($)ProductCandidate$ / sharesshares	Jul. 31, 2019USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)
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
Milestone payment		$ 2,500,000
Accrued milestones			$ 0
Shire Agreement | Shire | Maralixibat
Asset Acquisitions [Line Items]
Milestone payments, payable	109,500,000
Milestone payments, payable upon approval	25,000,000
Shire Agreement | Shire | Volixibat
Asset Acquisitions [Line Items]
Milestone payments, payable	$ 30,000,000
Shire Agreement | Shire | Redeemable Common Stock
Asset Acquisitions [Line Items]
Temporary equity, shares issued | shares	1,859,151
Issuance of Series A convertible preferred stock at $1.00259507 per share, net of issuance costs of $23	$ 7,000,000
Shares issued, price per share | $ / shares	$ 3.76
Transition Services Agreement | Shire | Shire Provided Services
Asset Acquisitions [Line Items]
Research and development			0	$ 300,000
Transition Services Agreement | Shire | Pass-through Cost
Asset Acquisitions [Line Items]
Research and development				$ 100,000
Assigned License Agreement | Satiogen Pharmaceuticals, Inc.
Asset Acquisitions [Line Items]
Milestone payments, payable	$ 10,500,000
Milestone payments, payable upon approval	5,000,000
Milestone payment		$ 500,000
Accrued milestones			0
Milestone payments, payable upon initiation	500,000
Milestone payments, payable upon commercialization	5,000,000
Assigned License Agreement | Sanofi-Aventis Deutschland GmbH
Asset Acquisitions [Line Items]
Milestone payments, payable	$ 36,000,000
Royalty obligations payment period	10 years
Milestones accrued			$ 0

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) - Additional Information (Details)	Nov. 05, 2018shares	Jul. 31, 2019shares	Apr. 30, 2019shares	Mar. 31, 2020Vote$ / sharesshares	Oct. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2019$ / sharesshares	Aug. 31, 2018$ / shares
Class of Stock [Line Items]
Common stock, par value | $ / shares				$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Common Stock Agreement | Redeemable Common Stock
Class of Stock [Line Items]
Number of shares issued	1,859,151
Common Stock
Class of Stock [Line Items]
Number of shares issued upon conversion of series A preferred stock		14,969,118
Number of shares repurchased			25,782
Number of shares subject to repurchase				356,251		389,649
Common stock, voting rights				Each share of common stock is entitled to one voting right.
Number of vote entitled for each common stockholder | Vote				1
Common Stock | Founder
Class of Stock [Line Items]
Stock issued for services, shares					1,187,500
Stock issued for services, value | $					$ 950
Common Stock | Restricted Stock | Founder
Class of Stock [Line Items]
Stock issued for services, shares	562,500
Vesting period	4 years

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Schedule of Common Stock Reserved for Issuance (Details) - shares	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved for issuance	7,108,653	4,979,255
Stock Options
Class of Stock [Line Items]
Common stock reserved for issuance	4,436,862	3,366,812
Reserved for Future Stock Awards or Option Grants
Class of Stock [Line Items]
Common stock reserved for issuance	1,941,892	1,112,443
Reserved for Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock reserved for issuance	729,899	500,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 05, 2018	Jul. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Oct. 31, 2018	Mar. 18, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance			7,108,653				4,979,255
Common Stock | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued for services					1,187,500
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance			4,436,862				3,366,812
Expected dividend yield			0.00%	0.00%
Total unrecognized stock-based compensation related to unvested stock option awards granted			$ 33.4
Unrecognized stock-based compensation related to unvested stock, expected to recognize over weighted-average period			3 years 2 months 12 days
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			2 years 8 months 12 days
Share vested			33,398	35,156
Total unrecognized compensation expense related to unvested restricted stock			$ 1
Restricted Stock | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Measurement date fair value for stock issued for services	$ 2.936
Restricted Stock | Common Stock | Founder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued for services	562,500
Total compensation cost	$ 1.7
Vesting period	4 years
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance		1,401,443	1,191,892
Equity incentive plans, description		A total of 1,401,443 shares of common stock were approved to be initially reserved for issuance under the 2019 Plan, including 101,443 shares that remained available for issuance under the 2018 Plan as of July 17, 2019. 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, 2020, 1,191,892 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%
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance		101,443
2020 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock for future issuance						750,000
Number of shares, Granted			0
2019 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock approved and reserved for issuance			729,899
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 lessor 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. As of March 31, 2020, the ESPP was not activated and there were 729,899 shares available for future issuance.
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%
Stock issued for services		500,000
Annual increase in common stock available for issuance, shares		1,500,000

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, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price		$ 2.94
Exercise price, minimum	$ 10.40
Exercise price, maximum	$ 24.52
Expected term (in years)		6 years 3 months
Expected volatility		74.53%
Expected volatility, minimum	77.07%
Expected volatility, maximum	88.11%
Risk-free interest rate		2.46%
Risk-free interest rate, minimum	0.51%
Risk-free interest rate, maximum	1.73%
Expected dividend yield	0.00%	0.00%
Grant date fair value of options granted		$ 4.35
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 29 days
Grant date fair value of options granted	$ 16.59
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 6 months
Grant date fair value of options granted	$ 7.38

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, 2020	Dec. 31, 2019
Options, Outstanding
Number of shares, Outstanding, Beginning balance	3,366,812
Number of shares, Granted	1,115,300
Number of shares, Canceled and forfeited	(45,250)
Number of shares, Outstanding, Ending balance	4,436,862	3,366,812
Number of shares, Vested and exercisable	499,844
Weighted-average exercise price, Outstanding
Weighted-average exercise price, Outstanding, Beginning balance	$ 5.14
Weighted-average exercise price, Granted	18.68
Weighted-average exercise price, Canceled and forfeited	10.28
Weighted-average exercise price, Outstanding, Ending balance	8.50	$ 5.14
Weighted-average exercise price, Vested and exercisable	$ 3.35
Share-based Payment Award, Options, Additional Disclosures
Weighted-average remaining contractual life, Outstanding	9 years 3 months 18 days	9 years 3 months 18 days
Weighted-average remaining contractual life, Granted	9 years 9 months 18 days
Weighted-average remaining contractual life, Canceled and forfeited	9 years 4 months 24 days
Weighted-average remaining contractual life, Vested and exercisable	9 years
Aggregate intrinsic value, Outstanding	$ 29,809	$ 65,235
Aggregate intrinsic value, Vested and exercisable	$ 5,390

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock-based Compensation Expense Reflected in Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 2,573	$ 218
General and Administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	1,532	147
Research and Development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 1,041	$ 71

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2019USD ($)ft²	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)	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		Pursuant to the 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.
Existence of option to extend		true
Term of extension of lease					5 years
Tenant improvement allowance					$ 400
Operating lease right-of-use assets		$ 2,280		$ 2,361
Lease liability		$ 3,614
Estimated weighted-average incremental borrowing rate		8.00%
Weighted-average remaining lease term		4 years 10 months 24 days
Rent expense		$ 200	$ 100
Amended Operating Lease Agreement
Lessee Lease Description [Line Items]
Term of lease	5 years
Tenant improvement allowance	$ 800
Additional area of office space | ft²	5,555
Lease expiration, month and year	2025-03
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, 2020USD ($)
Leases [Abstract]
2020 (remaining nine months)	$ 567
2021	865
2022	890
2023	918
2024	928
2025	230
Total undiscounted lease payments	4,398
Less: imputed interest	(784)
Total lease liability	$ 3,614