0001628280-21-002272 | 10-K | XBRL Viewer | Arcutis Biotherapeutics INC

Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2020	Feb. 11, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39186
Entity Registrant Name	ARCUTIS BIOTHERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-2974255
Entity Address, Address Line One	3027 Townsgate Road
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Westlake Village
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91361
City Area Code	805
Local Phone Number	418-5006
Title of 12(b) Security	Common Stock, par value $0.0001
Trading Symbol	ARQT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 619,916,280
Entity Common Stock, Shares Outstanding		50,084,677
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement for the registrant’s 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Form 10-K to the extent stated herein. The Proxy Statement will be filed within 120 days of the registrant’s fiscal year ended December 31, 2020.
Entity Central Index Key	0001787306
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 65,082,000	$ 63,336,000
Restricted cash	1,542,000	0
Marketable securities	219,359,000	37,929,000
Prepaid expenses and other current assets	6,843,000	5,209,000
Total current assets	292,826,000	106,474,000
Property and equipment, net	2,016,000	227,000
Operating lease right-of-use asset	3,349,000	264,000
Other assets	78,000	47,000
Total assets	298,269,000	107,012,000
Current liabilities:
Accounts payable	7,140,000	1,405,000
Accrued liabilities	15,462,000	3,654,000
Operating lease liability	0	178,000
Total current liabilities	22,602,000	5,237,000
Operating lease liability, noncurrent	4,964,000	129,000
Other long-term liabilities	82,000	184,000
Total liabilities	27,648,000	5,550,000
Commitments and contingencies
Convertible preferred stock, $0.0001 par value; no shares and 48,787,898 shares authorized at December 31, 2020 and December 31, 2019, respectively; no shares and 24,385,388 shares issued and outstanding at December 31, 2020, and December 31, 2019, respectively; aggregate liquidation preference of $166,300 at December 31, 2019	0	166,491,000
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value; 10,000,000 and no shares authorized at December 31, 2020 and December 31, 2019, respectively; no shares issued and outstanding at December 31, 2020 and December 31, 2019;	0	0
Common stock, $0.0001 par value; 300,000,000 and 65,820,000 shares authorized at December 31, 2020 and December 31, 2019, respectively; 43,677,817 and 2,879,763 shares issued at December 31, 2020 and December 31, 2019, respectively; 43,338,438 and 2,120,853 shares outstanding at December 31, 2020 and December 31, 2019, respectively	4,000	0
Additional paid-in capital	472,569,000	1,244,000
Accumulated other comprehensive loss	(2,000)	(1,000)
Accumulated deficit	(201,950,000)	(66,272,000)
Total stockholders’ equity (deficit)	270,621,000	(65,029,000)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 298,269,000	$ 107,012,000

Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Convertible preferred stock, par value (In USD per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized (in shares)	0	48,787,898
Convertible preferred stock, shares issued (in shares)	0	24,385,388
Convertible preferred stock, shares outstanding (in shares)	0	24,385,388
Convertible preferred stock, liquidation preference		$ 166,300,000
Preferred stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	65,820,000
Common stock, shares, issued (in shares)	43,677,817	2,879,763
Common stock, shares outstanding (in shares)	43,338,438	2,120,853

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 115,308	$ 36,522	$ 17,940
General and administrative	21,337	6,610	1,795
Total operating expenses	136,645	43,132	19,735
Loss from operations	(136,645)	(43,132)	(19,735)
Other income, net	967	1,136	480
Net loss	(135,678)	(41,996)	(19,255)
Other comprehensive loss:
Unrealized loss on marketable securities	(1)	(1)	0
Comprehensive loss	$ (135,679)	$ (41,997)	$ (19,255)
Per share information:
Net loss per share, basic and diluted (in USD per share)	$ (3.80)	$ (22.78)	$ (15.53)
Weighted-average shares used in computing net loss per share, basic and diluted (in shares)	35,668,152	1,843,213	1,239,689

Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	IPO	Secondary equity public offering	Private placement	Common Stock	Common Stock IPO	Common Stock Secondary equity public offering	Common Stock Private placement	Additional Paid-In Capital	Additional Paid-In Capital IPO	Additional Paid-In Capital Secondary equity public offering	Additional Paid-In Capital Private placement	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance, convertible preferred stock (in shares) at Dec. 31, 2017	3,740,791
Beginning balance at Dec. 31, 2017	$ 7,154
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net of issuance costs (in shares)		3,156,784	8,880,462
Issuance of convertible preferred stock, net of issuance costs		$ 7,186	$ 54,912
Issuance of convertible preferred stock in connection with license agreement (in shares)			484,388
Issuance of convertible preferred stock in connection with license agreement			$ 3,000
Ending balance, convertible preferred stock (in shares) at Dec. 31, 2018	16,262,425
Ending balance at Dec. 31, 2018	$ 72,252
Beginning balance (in shares) at Dec. 31, 2017								922,622
Beginning balance at Dec. 31, 2017	$ (4,993)							$ 0				$ 28				$ 0	$ (5,021)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)	918,885							114,225
Issuance of common stock upon the exercise of stock options	$ 43											43
Vesting of founder shares subject to repurchase (in shares)								360,560
Lapse of repurchase rights related to common stock issued pursuant to early exercises (in shares)								160,493
Lapse of repurchase rights related to common stock issued pursuant to early exercises	67											67
Stock-based compensation expense	151											151
Unrealized loss on marketable securities	0
Net Loss	(19,255)																(19,255)
Ending balance at Dec. 31, 2018	$ (23,987)							$ 0				289				0	(24,276)
Ending balance (in shares) at Dec. 31, 2018								1,557,900
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net of issuance costs (in shares)				8,122,963
Issuance of convertible preferred stock, net of issuance costs				$ 94,239
Ending balance, convertible preferred stock (in shares) at Dec. 31, 2019	24,385,388	6,897,575	9,364,850	8,122,963
Ending balance at Dec. 31, 2019	$ 166,491	$ 14,340	$ 57,912	$ 94,239
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)	250,865							15,885
Issuance of common stock upon the exercise of stock options	$ 9											9
Issuance of restricted stock units (in shares)								13,245
Issuance of restricted stock units	8											8
Vesting of founder shares subject to repurchase (in shares)								275,726
Lapse of repurchase rights related to common stock issued pursuant to early exercises (in shares)								258,097
Lapse of repurchase rights related to common stock issued pursuant to early exercises	114											114
Stock-based compensation expense	824											824
Unrealized loss on marketable securities	(1)															(1)
Net Loss	(41,996)																(41,996)
Ending balance at Dec. 31, 2019	$ (65,029)							$ 0				1,244				(1)	(66,272)
Ending balance (in shares) at Dec. 31, 2019								2,120,853
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of preferred stock into common stock upon initial public offering (in shares)	(24,385,388)
Conversion of preferred stock into common stock upon initial public offering	$ (166,491)
Ending balance, convertible preferred stock (in shares) at Dec. 31, 2020	0
Ending balance at Dec. 31, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of stock options (in shares)	197,228							140,226
Issuance of common stock upon the exercise of stock options	$ 430											430
Vesting of founder shares subject to repurchase (in shares)								137,863
Conversion of preferred stock into common stock upon initial public offering (in shares)								24,385,388
Conversion of preferred stock into common stock upon initial public offering	166,491							$ 2				166,489
Issuance of shares of common stock, net of issuance costs (in shares)									10,781,250	4,000,000	1,400,000
Issuance of shares of common stock, net of issuance costs					$ 167,241	$ 93,360	$ 35,000		$ 1				$ 167,240	$ 93,360	$ 35,000
Lapse of repurchase rights related to common stock issued pursuant to early exercises (in shares)								338,670
Lapse of repurchase rights related to common stock issued pursuant to early exercises	247							$ 1				246
Shares issued pursuant to the employee stock purchase plan (in shares)								34,188
Shares issued pursuant to the employee stock purchase plan	617											617
Stock-based compensation expense	7,943											7,943
Unrealized loss on marketable securities	(1)															(1)
Net Loss	(135,678)																(135,678)
Ending balance at Dec. 31, 2020	$ 270,621							$ 4				$ 472,569				$ (2)	$ (201,950)
Ending balance (in shares) at Dec. 31, 2020								43,338,438

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible preferred stock liability	$ 0	$ 0	$ 891
Series A Convertible Preferred Stock
Stock issuance costs			21
Convertible preferred stock liability			891
Series B Convertible Preferred Stock
Stock issuance costs			$ 88
Series C Convertible Preferred Stock
Stock issuance costs		$ 262
Common Stock \| IPO
Stock issuance costs	16,040
Common Stock \| Secondary equity public offering
Stock issuance costs	$ 6,640

Statements of Cash Flows - USD ($)	12 Months Ended
Statements of Cash Flows - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (135,678,000)	$ (41,996,000)	$ (19,255,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	122,000	68,000	0
Non-cash lease expense	333,000	127,000	0
Net amortization/accretion on marketable securities	72,000	(354,000)	(14,000)
Stock-based compensation	7,943,000	824,000	151,000
Loss on disposal of property and equipment	42,000	0	0
Issuance of convertible preferred stock in connection with license agreement	0	0	3,000,000
Change in fair value of convertible preferred stock liability	0	0	(75,000)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,412,000)	(3,304,000)	243,000
Other assets	0	(47,000)	0
Accounts payable	5,674,000	(458,000)	1,264,000
Accrued liabilities	11,877,000	2,388,000	601,000
Operating lease liabilities	(6,000)	(84,000)	0
Net cash used in operating activities	(113,033,000)	(42,836,000)	(14,085,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(279,103,000)	(60,830,000)	(11,532,000)
Proceeds from maturities of marketable securities	97,600,000	34,800,000	0
Purchases of property and equipment	(321,000)	(295,000)	0
Net cash used in investing activities	(181,824,000)	(26,325,000)	(11,532,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock upon exercise of stock options	526,000	265,000	386,000
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	94,239,000	61,207,000
Proceeds from initial public offering, net of issuance costs	168,642,000	0	0
Proceeds from issuance of common stock, net of issuance costs	128,360,000	0	0
Proceeds from issuance of common stock for ESPP purchase	617,000	0	0
Payment of financing costs	0	(1,401,000)	0
Net cash provided by financing activities	298,145,000	93,103,000	61,593,000
Net increase in cash, cash equivalents and restricted cash	3,288,000	23,942,000	35,976,000
Cash, cash equivalents and restricted cash at beginning of period	63,336,000	39,394,000	3,418,000
Cash, cash equivalents and restricted cash at end of period	66,624,000	63,336,000	39,394,000
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Conversion of preferred stock to common stock and APIC	166,491,000	0	0
Reclassification of convertible preferred stock liability to Series A convertible preferred stock	0	0	891,000
Right-of-use asset obtained in exchange for lease liability	3,617,000	391,000	0
Reduction in right-of-use asset upon reassessment of lease term	123,000	0	0
Deferred financing costs included in accounts payable and accrued liabilities	$ 0	$ 346,000	$ 0

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Arcutis Biotherapeutics, Inc., or the Company, is a late-stage biopharmaceutical company focused on developing and commercializing treatments for dermatological diseases with high unmet medical needs. The Company’s current portfolio is comprised of highly differentiated topical treatments with significant promise to treat immune-mediated dermatological diseases and conditions. The Company believes it has built the industry's leading platform for dermatologic product development. The Company’s strategy is to focus on validated biological targets and to use our platform and deep dermatology expertise to develop differentiated products that have the potential to address the major shortcomings of existing therapies in its targeted indications. The Company believes this strategy uniquely positions it to rapidly advance its goal of bridging the treatment innovation gap in dermatology while maximizing its probability of technical success. On January 17, 2020, the Company's board of directors approved a 1-for-2.0007 reverse stock split of the Company’s capital stock and the Company filed a certificate of amendment to its restated certificate of incorporation to effect the split. The par value and authorized shares of common stock and convertible preferred stock were not adjusted as a result of the reverse split. All share and per share information included in the accompanying financial statements has been adjusted to reflect this reverse stock split. Initial Public Offering and Follow-On Financings On February 4, 2020, the Company closed an initial public offering (IPO) issuing and selling 10,781,250 shares of common stock at a public offering price of $17.00 per share, including 1,406,250 shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares. The aggregate net proceeds received by the Company from the offering were approximately $167.2 million, after deducting underwriting discounts, commissions and offering related transaction costs. Upon the closing of the IPO, all of the outstanding shares of convertible preferred stock automatically converted into shares of common stock. Subsequent to the closing of the IPO, there were no shares of convertible preferred stock outstanding. On October 6, 2020, the Company completed a public offering of 4,000,000 shares of common stock at an offering price of $25.00 per share, receiving aggregate net proceeds of approximately $93.4 million after deducting the underwriting discounts, commissions and offering related transaction costs. In addition, the Company concurrently sold 1,400,000 shares of common stock in a private placement exempt from the registration requirements of the Securities Act of 1933, as amended, at a price per share equal to the public offering price, receiving net proceeds of $35.0 million. On February 5, 2021, the Company completed a public offering of 6,325,000 shares of stock at an offering price of $35.00 per share, including 825,000 shares sold pursuant to the underwriters full exercise of their option to purchase additional shares. The aggregate net proceeds received by the Company were approximately $207.4 million, after deducting underwriting discounts, commissions and estimated offering expenses. See Note 13. Liquidity The Company has incurred significant losses and negative cash flows from operations since its inception and had an accumulated deficit of $202.0 million and $66.3 million as of December 31, 2020 and 2019, respectively. The Company had cash, cash equivalents, restricted cash and marketable securities of $286.0 million and $101.3 million as of December 31, 2020 and 2019, respectively. In addition, on February 5, 2021, the Company received $180.3 million in net proceeds from an equity offering. See Note 13. Prior to selling common stock in its IPO and follow-on financings, the Company had historically financed its operations primarily through the sale of its convertible preferred stock. Management expects operating losses to continue for the foreseeable future. The Company believes that its existing capital resources will be sufficient to meet the projected operating requirements for at least 12 months from the date of issuance of its financial statements. The Company will be required to raise additional capital to fund future operations. However, no assurance can be given as to whether additional needed financing will be available on terms acceptable to the Company, if at all. If sufficient funds on acceptable terms are not available when needed, the Company may be required to curtail planned activities to significantly reduce its operating expenses. Failure to manage discretionary spending or raise additional financing, as needed, may adversely impact the Company’s ability to achieve its intended business objectives and have an adverse effect on its results of operations and future prospects. Coronavirus Outbreak In March 2020, the World Health Organization declared a pandemic related to the global novel coronavirus disease 2019 (COVID-19) outbreak. As of February 16, 2021, the Company’s operations have not been significantly impacted by the COVID-19 pandemic. The Company is monitoring the impact COVID-19 may have on the clinical development of its product candidates, including potential delays or modifications to its ongoing and planned trials. However, the Company cannot at this time predict the specific extent, duration, or full impact that the COVID-19 outbreak will have on its financial condition and operations, including ongoing and planned clinical trials.

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The Company’s financial statements have been prepared in accordance with United States generally accepted accounting principles (U.S. GAAP). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates such estimates and assumptions for continued reasonableness. In particular, management makes estimates with respect to accruals for research and development activities, fair value of common stock and convertible preferred stock (prior to the IPO completed in January 2020), stock-based compensation expense and income taxes. Appropriate adjustments, if any, to the estimates used are made prospectively based upon such periodic evaluation. Actual results could differ from those estimates. Segments To date, the Company has viewed its financial information on an aggregate basis for the purposes of evaluating financial performance and allocating the Company’s resources. Accordingly, the Company has determined that it operates in one segment. Cash and Cash Equivalents The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of money market funds, commercial paper, and U.S. Treasury securities. Restricted Cash As of December 31, 2020, the Company held $1.5 million of restricted cash as collateral for a letter of credit related to our amended office space lease. As of December 31, 2019, the Company did not hold any restricted cash. See Note 7. Marketable Securities Marketable securities consist of investment grade short to intermediate-term fixed income investments that have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in fixed income securities at the time of purchase. Available-for-sale securities with original maturities beyond three months at the date of purchase are classified as current based on their availability for use in current operations. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. Realized gains and losses as well as credit losses, if any, on marketable securities are included in other income, net. The Company evaluated the underlying credit quality and credit ratings of the issuers during the period. To date, no such credit losses have occurred or have been recorded. The cost of investments sold is based on the specific-identification method. As of December 31, 2020, there were net unrealized losses on marketable securities of $2,000, and as of December 31, 2019, there were net unrealized losses on marketable securities of $1,000. Unrealized gains and losses on marketable securities are reported as a component of accumulated other comprehensive loss on the balance sheets. Realized gains or losses on investments for the year ended December 31, 2020 were not material. There were no realized gains or losses on investments for the year ended December 31, 2019. Interest on marketable securities is included in other income, net. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash to the extent recorded on the balance sheets. Management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Fair Value Measurement The Company’s financial instruments, in addition to those presented in Note 3, include cash equivalents, accounts payable and accrued liabilities. The carrying amount of cash equivalents, accounts payable and accrued liabilities approximate their fair values due to their short maturities. Assets and liabilities recorded at fair value on a recurring basis on the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets which range from three to five years. Leasehold improvements are depreciated on a straight-line basis over the shorter of their estimated useful lives or lease terms. Maintenance and repairs are expensed as incurred. The Company reviews the carrying values of its property and equipment for possible impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. There were no impairments recognized during the years ended December 31, 2020 and 2019. Leases The Company determines if an arrangement is or contains a lease at inception. Right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases along with the initial measurement and recognition of the associated ROU assets and lease liabilities is performed at the lease commencement date. The measurement of lease liabilities is based on the present value of lease payments over the lease term. The Company uses its incremental borrowing rate, based on the information available at commencement date, to determine the present value of lease payments when its leases do not provide an implicit rate. The Company uses the implicit rate when readily determinable. The ROU asset is based on the measurement of the lease liability, includes any lease payments made prior to or on lease commencement and is adjusted for lease incentives and initial direct costs incurred, as applicable. Lease expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company considers a lease term to be the non-cancelable period that it has the right to use the underlying asset, including any periods where it is reasonably assured the Company will exercise the option to extend the contract. Periods covered by an option to extend are included in the lease term if the lessor controls the exercise of that option. The Company’s lease agreements includes lease and non-lease components and the Company has elected to not separate such components for all classes of assets. Further, the Company elected the short-term lease exception policy, permitting it to not apply the recognition requirements of this standard to leases with terms of 12 months or less (short-term leases) for all classes of assets. Preclinical and Clinical Accruals and Costs The Company records accrued liabilities for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical studies, clinical trials and contract manufacturing activities. These costs are a significant component of the Company’s research and development expenses. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers under the service agreements. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. For the years ended December 31, 2020, 2019 and 2018, the Company has not experienced any material differences between accrued costs and actual costs incurred. Convertible Preferred Stock Prior to its IPO, the Company classified its outstanding convertible preferred stock outside of stockholders’ equity (deficit) on its balance sheets as the requirements of triggering a deemed liquidation event, as defined within its amended and restated certificate of incorporation, were not entirely within the Company’s control. In the event of such a deemed liquidation event, the proceeds from the event were to be distributed in accordance with the liquidation preferences, provided that the holders of convertible preferred stock had not converted their shares into common stock. The Company recorded the issuance of convertible preferred stock at the issuance price less related issuance costs. The Company did not adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty as to whether or when a deemed liquidation event may have occurred. In connection with the IPO in February 2020, the Company’s outstanding shares of convertible preferred stock were automatically converted into 24,385,388 shares of common stock. Research and Development Research and development expenses include costs directly attributable to the conduct of research and development programs, including the cost of salaries, payroll taxes, employee benefits, license fees, stock-based compensation expense, materials, supplies, and the cost of services provided by outside contractors. All costs associated with research and development are expensed as incurred. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods are received or services are rendered. Such payments are evaluated for current or long-term classification based on when they will be realized. The Company has entered into and may continue to enter into, license agreements to access and utilize certain technology. In each case, the Company evaluates if the license agreement results in the acquisition of an asset or a business. To date, none of the Company’s license agreements have been considered an acquisition of a business. For asset acquisitions, the upfront payments to acquire such licenses, as well as any future milestone payments made before product approval that do not meet the definition of a derivative, are immediately recognized as research and development expense when paid or become payable, provided there is no alternative future use of the rights in other research and development projects. Stock-Based Compensation The Company accounts for share-based payments at fair value. The fair value of stock options is measured using the Black-Scholes option-pricing model. For share-based awards that vest subject to the satisfaction of a service requirement, the fair value measurement date for such awards is the date of grant and the expense is recognized on a straight-line basis, over the expected vesting period. For share-based awards that vest subject to a performance condition, the Company will recognize compensation cost for awards if and when the Company concludes that it is probable that the awards with a performance condition will be achieved on an accelerated attribution method. The Company accounts for forfeitures as they occur. Income Taxes Income taxes are accounted for using the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. The Company records a valuation allowance to reduce deferred tax assets to an amount for which realization is more likely than not. Due to the Company’s historical operating performance and the recorded cumulative net losses in prior fiscal periods, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties incurred in relation to the unrecognized tax benefits. The United States Congress enacted the Families First Coronavirus Response Act (FFCR Act) on March 18, 2020 and the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) on March 27, 2020. The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the U.S. economy and fund a nationwide effort to curtail the effect of COVID-19. The FFCR Act and CARES Act include numerous tax-related provisions including modifications to the limitations on business interest expense and net operating losses (NOLs), certain refundable employee retention credits, as well as a payment delay of employer payroll taxes in 2020 after the date of enactment. On June 29, 2020, the California State Assembly Bill 85 (Trailer Bill) was enacted which suspends the use of California NOL deductions and certain tax credits, including research and development credits, for the 2020, 2021, and 2022 tax years. The Company does not expect the FFCR Act, CARES Act or Trailer Bill to have a material impact on the Company’s financial statements. Variable Interest Entities The Company reviews agreements it enters into with third-party entities, pursuant to which the Company may have a variable interest in the entity, in order to determine if the entity is a variable interest entity (VIE). If the entity is a VIE, the Company assesses whether or not it is the primary beneficiary of that entity. In determining whether the Company is the primary beneficiary of an entity, the Company applies a qualitative approach that determines whether it has both (i) the power to direct the economically significant activities of the entity and (ii) the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. If the Company determines it is the primary beneficiary of a VIE, it consolidates that VIE into the Company’s financial statements. The Company’s determination about whether it should consolidate such VIEs is made continuously as changes to existing relationships or future transactions may result in a consolidation or deconsolidation event. The Company currently does not consolidate any VIEs. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive. Shares of common stock subject to repurchase are excluded from the weighted-average shares. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (i) no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU No. 2018-13, which removes, modifies, and adds various disclosure requirements on fair value measurements in Topic 820. ASU No. 2018-13 is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company early adopted this standard as of January 1, 2020, and it did not have a material impact on its financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU No. 2016-13. This update requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations now include forward-looking information in the determination of their credit loss estimates. Many of the previous loss estimation techniques are still permitted, although the inputs to those techniques have changed to reflect the full amount of expected credit losses. In addition, this update amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The Company early adopted this standard as of January 1, 2020, and it did not have a material impact on its financial statements. There was no impact on the Company's financial statements from credit losses for the year ended December 31, 2020.In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740), or ASU No. 2019-12, which amends the existing guidance relating to the accounting for income taxes. This standard is intended to simplify the accounting for income taxes by removing certain exceptions to the general principles of accounting for income taxes and to improve the consistent application of GAAP for other areas of accounting for income taxes by clarifying and amending existing guidance. The standard is effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods therein. Early adoption is permitted. An entity that elects early adoption in an interim period should reflect any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an entity that elects early adoption should adopt all the amendments in the same period. The Company early adopted this guidance as of January 1, 2020, and it did not have a material impact on its financial statements.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	65,082	$	—	$	—	$	65,082
Commercial paper	—		45,518		—		45,518

U.S. Treasury securities	173,841		—		—		173,841
Total assets	$	238,923	$	45,518	$	—	$	284,441


	December 31, 2019
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	43,558	$	—	$	—	$	43,558
Commercial paper	—		44,689		—		44,689
U.S. Treasury securities	13,018		—		—		13,018
Total assets	$	56,576	$	44,689	$	—	$	101,265

______________

(1)This balance includes cash requirements settled on a nightly basis.

Commercial paper, money market funds and U.S. Treasury securities are valued taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs.

The following table summarizes the estimated value of the Company’s cash, cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands):


	December 31, 2020
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:

Money market funds(1)	$	65,082	$	—	$	—	$	65,082

Total cash and cash equivalents	$	65,082	$	—	$	—	$	65,082
Marketable securities:
Commercial paper	$	45,518	—		—		$	45,518

U.S. Treasury securities	173,843		7		(9)		173,841
Total marketable securities	$	219,361	$	7	$	(9)	$	219,359

______________

(1)This balance includes cash requirements settled on a nightly basis.


	December 31, 2019
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:
Commercial paper	$	11,780	$	—	$	—	$	11,780
Money market funds(1)	43,558		—		—		43,558
U.S. Treasury securities	7,998		—		—		7,998
Total cash and cash equivalents	$	63,336	$	—	$	—	$	63,336
Marketable securities:
Commercial paper	$	32,909	$	—	$	—	$	32,909
U.S. Treasury securities	5,021		—		(1)		5,020
Total marketable securities	$	37,930	$	—	$	(1)	$	37,929

______________

(1)This balance includes cash requirements settled on a nightly basis.

Realized gains or losses on investments for the year ended December 31, 2020 were not material. There were no realized gains or losses on investments for the year ended December 31, 2019. As of December 31, 2020 and 2019, unrealized losses on marketable securities were not material, and accordingly, no allowance for credit losses were recorded. As of December 31, 2020 and 2019, all securities have a maturity of one year or less and all securities with gross unrealized losses have been in a continuous loss position for less than one year.

- Definition

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

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):


	December 31, 2020		December 31, 2019
Prepaid clinical trial costs	$	4,865	$	2,998
Tax credits	510		145
Prepaid insurance	249		62
Deferred financing costs	—		1,747
Other prepaid expenses and current assets	1,219		257
Total prepaid expenses and other current assets	$	6,843	$	5,209

Accrued Liabilities

Accrued liabilities consist of the following (in thousands):


	December 31, 2020		December 31, 2019
Clinical trial accruals	$	9,754	$	1,497
Accrued compensation	4,434		1,379
Early exercise liability, current	176		225
Accrued expenses and other current liabilities	1,098		553
Total accrued liabilities	$	15,462	$	3,654

Property and Equipment, net

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment, net

Property and equipment, net consists of the following (in thousands):


		December 31,
	Useful life (in years)	2020		2019
Computer hardware	3	$	286	$	80
Furniture and fixtures	5	230		60
Construction in process		298		—
Leasehold improvements		1,280		155
Property and equipment, gross		2,094		295
Less accumulated depreciation		(78)		(68)
Property and equipment, net		$	2,016	$	227

Leasehold improvements are depreciated over the term of the lease. Depreciation expense was $122,000 and $68,000 for the years ended December 31, 2020 and 2019, respectively. There was no depreciation expense for the year ended December 31, 2018.

License Agreements	12 Months Ended
License Agreements	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License Agreements	License Agreements AstraZeneca License Agreement In July 2018, the Company entered into an exclusive license agreement, or the AstraZeneca License Agreement, with AstraZeneca AB (AstraZeneca), granting the Company a worldwide exclusive license, with the right to sublicense through multiple tiers, under certain AstraZeneca-controlled patent rights, know-how and regulatory documentation, to research, develop, manufacture, commercialize and otherwise exploit products containing roflumilast in topical forms, as well as delivery systems sold with or for the administration of roflumilast, or collectively, the AZ-Licensed Products, for all diagnostic, prophylactic and therapeutic uses for human dermatological indications, or the Dermatology Field. Under this agreement, the Company has sole responsibility for development, regulatory, and commercialization activities for the AZ-Licensed Products in the Dermatology Field, at its expense, and it shall use commercially reasonable efforts to develop, obtain and maintain regulatory approvals for, and commercialize the AZ-Licensed Products in the Dermatology Field in each of the United States, Italy, Spain, Germany, the United Kingdom, France, China, and Japan. The Company paid AstraZeneca an upfront non-refundable cash payment of $1.0 million and issued 484,388 shares of Series B convertible preferred stock, valued at $3.0 million on the date of the AstraZeneca License Agreement. The Company subsequently paid AstraZeneca the first milestone cash payment of $2.0 million upon the completion of a Phase 2b study of roflumilast cream in plaque psoriasis in August 2019 for the achievement of positive Phase 2 data for an AZ-Licensed Product, which was recorded in research and development expense. The Company has agreed to make additional cash payments to AstraZeneca of up to an aggregate of $12.5 million upon the achievement of specified regulatory approval milestones with respect to the AZ-Licensed Products and payments up to an additional aggregate amount of $15.0 million upon the achievement of certain aggregate worldwide net sales milestones. With respect to any AZ-Licensed Products the Company commercializes under the AstraZeneca License Agreement, it will pay AstraZeneca a low to high single-digit percentage royalty rate on the Company’s, its affiliates’ and its sublicensees’ net sales of such AZ-Licensed Products, subject to specified reductions, until, as determined on an AZ-Licensed Product-by-AZ-Licensed Product and country-by-country basis, the later of the date of the expiration of the last-to-expire AstraZeneca-licensed patent right containing a valid claim in such country and ten years from the first commercial sale of such AZ-Licensed Product in such country. There were no payments made or due in connection with AZ-Licensed Products for the year ended December 31, 2020. For the year ended December 31, 2019, the Company recorded research and development expense of $2.0 million related to the milestone payment made upon the completion of a Phase 2B study of ARQ-151 in plaque psoriasis for the achievement of positive Phase 2 data for an AZ-Licensed Product For the year ended December 31, 2018, the Company recorded research and development expense of $4.0 million related to the upfront fee payment and the issuance of Series B convertible preferred stock. Hengrui Exclusive Option and License Agreement In January 2018, the Company entered into an exclusive option and license agreement, or the Hengrui License Agreement, with Jiangsu Hengrui Medicine Co., Ltd. (Hengrui), whereby Hengrui granted the Company an exclusive option to obtain certain exclusive rights to research, develop and commercialize products containing the compound designated by Hengrui as SHR0302, a Janus kinase type 1 inhibitor, in topical formulations for the treatment of skin diseases, disorders, and conditions in the United States, Japan, Canada and the European Union (including for clarity the United Kingdom). The Company made a $0.4 million upfront non-refundable cash payment to Hengrui upon execution of the Hengrui Option and License Agreement, which was recorded as research and development expense. In December 2019, the Company exercised its exclusive option under the agreement, for which it made a $1.5 million cash payment, which was recorded in research and development expense, and also contemporaneously amended the agreement to expand the territory to additionally include Canada. In addition, the Company has agreed to make cash payments of up to an aggregate of $20.5 million upon achievement of specified clinical development and regulatory approval milestones with respect to the licensed products and cash payments of up to an additional aggregate of $200.0 million in sales-based milestones based on certain aggregate annual net sales volumes with respect to a licensed product. With respect to any products the Company commercializes under the Hengrui License Agreement, it will pay tiered royalties to Hengrui on net sales of each licensed product by the Company, or its affiliates, or its sublicensees, ranging from mid single-digit to sub-teen percentage rates based on tiered annual net sales bands subject to specified reductions. The Company is obligated to pay royalties until the later of (1) expiration of the last valid claim of the licensed patent rights covering such licensed product in such country and (2) expiration of regulatory exclusivity for the relevant licensed product in the relevant country, on a licensed product-by-licensed product and country-by-country basis. Additionally, the Company is obligated to pay Hengrui a specified percentage, ranging from the low-thirties to the sub-teens, of certain non-royalty sublicensing income it receives from sublicensees of its rights to the licensed products, such percentage decreasing as the development stage of the licensed products advance. There were no payments made or due in connection with Hengrui for the year ended December 31, 2020. Hawkeye Collaboration Agreement In June 2019, the Company entered into a collaboration agreement, or Hawkeye Agreement, with Hawkeye Therapeutics, Inc. (Hawkeye), a related party with common ownership, for the development of one or more new applications of roflumilast. The Hawkeye Agreement grants Hawkeye an exclusive license to certain intellectual property developed under the agreement as it relates to the applications. Contemporaneously with the execution of the Hawkeye Agreement, the Company entered into a stock purchase agreement, purchasing 995,000 shares of Hawkeye’s common stock at $0.0001 per share, representing 19.9% of the outstanding common stock of Hawkeye. In the event that Hawkeye issues shares of Series A preferred stock with proceeds over $5.0 million, Hawkeye is required to issue to the Company a number of fully-paid fully-vested shares of common stock determined by dividing (i) $2,000,000 by (ii) an amount equal to the cash price per share for Series A preferred stock. Other than the potential issuance of this common stock, there are no upfront payments, milestones or royalties pursuant to the Hawkeye Agreement. The Company determined that Hawkeye is a VIE for which consolidation is not required as it is not the primary beneficiary.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Lease

The Company leases a facility in Westlake Village, California under an operating lease that commenced in February 2019. This lease was amended in April 2020 in order to relocate to a new expanded space comprising 22,643 square feet. At the time of the amendment, the Company reassessed the lease term of the original space in accordance with the option to terminate if leasing additional space in the same property. In connection with the reduction of the lease term for the original space, the Company reduced the ROU asset and lease liability balance by $123,000.

The Company recognized the ROU asset and lease liability for the new space on May 1, 2020, which was determined to be the lease commencement date, or the date on which the new space was made available to the Company for purposes of planning and constructing the leasehold improvements. The lease payment term for the new space began on December 30, 2020, which was 15 days after the leasehold improvements were substantially complete. The lease payments terminate 91 months thereafter, with a renewal option for a term of five years. The Company will have a one-time option to cancel the lease after month 67. The renewal and one-time cancellation options have not been considered in the determination of the ROU asset or lease liability, as the Company did not consider it reasonably certain it would exercise these options.

The lease is subject to fixed rate escalation increases with an initial base rent of $76,000 per month, and includes rent free periods aggregating approximately one year. As a result, the Company recognizes rent expense on a straight-line basis for the full amount of the commitment including the minimum rent increases over the life of the lease and the free rent period. The amended lease agreement provided for a leasehold improvement allowance up to $1.25 million. It also required the Company to have an available letter of credit of $1.5 million upon occupying the space, which is allowed to be reduced throughout the lease period as rent obligations are met. Accordingly, in November 2020, the Company entered into a letter of credit for $1.5 million, which it secured with a restricted cash account in the same amount. The restricted cash will be reduced by $308,000 on the first, second, third, and fourth anniversary and by $45,000 on the fifth anniversary from when the lease payment term began on December 30, 2020, with no further reductions thereafter.

In association with commencement of this new lease, the Company recorded lease liabilities and off-setting ROU assets of $3.6 million on its balance sheet as of June 30, 2020. Since the Company was reasonably certain to incur costs equal to or exceeding the leasehold improvement allowance of $1.25 million, the allowance was treated as a lease incentive that was payable to the Company at the lease commencement date. Accordingly, the leasehold improvement allowance was included in the measurement of the consideration in the contract at commencement, and was recognized as a reduction in the ROU asset and lease liability. Upon completion in December 2020, the leasehold improvements were reclassified from the lease liability to property and equipment and will be depreciated over the term of the lease.

The minimum annual rental payments of the Company’s operating lease liability as of December 31, 2020 are as follows (in thousands):


	Amounts
2021	$	114
2022	781
2023	965
2024	995
2025	1,024
Thereafter	2,794
Total minimum lease payments	$	6,673
Less: Amounts representing interest	(1,709)

Present value of lease payments	$	4,964

Operating lease liability, noncurrent	4,964
Total operating lease liability	$	4,964

Straight-line rent expense recognized for operating leases was $602,000 and $151,000 for the years ended December 31, 2020 and 2019, respectively. Rent expense for the year ended December 31, 2018 was not material. There were no significant variable lease payments, including non-lease components such as common area maintenance fees, recognized as rent expense for operating leases for the year ended December 31, 2020.

The following information represents supplemental disclosure for the statement of cash flows related to the Company’s operating lease (in thousands):


	December 31, 2020
Cash flows from operating activities
Cash paid for amounts included in the measurement of lease liabilities	$	192

The following summarizes additional information related to the operating lease:


	December 31, 2020
Weighted-average remaining lease term (in years)	7.6
Weighted-average discount rate	7.0	%

Indemnification

In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company has also entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by California corporate law. The Company currently has directors’ and officers’ insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. The Company believes any potential loss exposure under these indemnification agreements in excess of applicable insurance coverage is minimal.

Convertible Preferred Stock and Stockholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Convertible Preferred Stock and Stockholders' Equity (Deficit)

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

Convertible Preferred Stock

Convertible preferred stock as of December 31, 2019 consisted of the following (in thousands, except share amounts):


Convertible Preferred Stock	Shares Authorized	Shares Issued and Outstanding	Net Carrying Value		Liquidation Preference
Series A	13,800,000	6,897,575	$	14,340	$	13,800
Series B	18,736,270	9,364,850	57,912		58,000
Series C	16,251,628	8,122,963	94,239		94,500
Total	48,787,898	24,385,388	$	166,491	$	166,300

In connection with the Company's IPO in February 2020, all of the Company’s outstanding shares of convertible preferred stock were automatically converted into 24,385,388 shares of common stock.

In October 2019, the Company issued 8,122,963 shares of Series C convertible preferred stock at a purchase price of $11.63 per share for total net proceeds of $94.2 million, some of which were to related parties.

In September 2018, the Company issued 9,364,850 shares of Series B convertible preferred stock at a purchase price of $6.19 per share for total net proceeds of $54.9 million, some of which were to related parties.

In April 2017 and March 2018, the Company issued 3,590,845 and 3,156,784 shares, respectively, of Series A convertible preferred stock at a purchase price of $2.00 per share for net proceeds of $13.4 million. Additionally, in April 2017, the Company issued 149,946 shares of Series A convertible preferred stock as a result of the conversion of convertible promissory notes.

Common Stock

The holders of the Company’s common stock have one vote for each share of common stock. Common stockholders are entitled to dividends when, as, and if declared by the board of directors. The holders have no preemptive or other subscription rights and there are no redemption or sinking fund provisions with respect to such shares. As of December 31, 2020, no dividends had been declared by the board of directors.

The Company reserved the following shares of common stock for issuance as follows:


	December 31,
	2020	2019
Convertible preferred stock outstanding	—	24,385,388
Options issued and outstanding	3,655,945	2,516,470
Common stock awards available for grant under employee benefit plans	2,501,329	1,550,150
Restricted stock units outstanding	162,930	—
Total common stock reserved	6,320,204	28,452,008

Authorized Share Capital

On February 4, 2020, the Company’s certificate of incorporation was amended and restated to provide for 300,000,000 authorized shares of common stock with a par value of $0.0001 per share and 10,000,000 authorized shares of preferred stock with a par value of $0.0001 per share. There were no shares of preferred stock outstanding as of December 31, 2020 and 2019.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

In January 2020, the Company’s board of directors approved the 2020 Equity Incentive Plan (2020 Plan), which became effective January 30, 2020 in connection with the IPO. The 2020 Plan serves as the successor incentive award plan to the Company’s 2017 Equity Incentive Plan, (2017 Plan), and has 2,134,000 shares of common stock available for issuance pursuant to a variety of stock-based compensation awards, including stock options, stock appreciation rights, restricted stock awards, restricted stock unit (RSU) awards and other stock-based awards, plus 1,550,150 shares of common stock that were reserved for issuance pursuant to future awards under the 2017 Plan at the time the 2020 Plan became effective, plus shares represented by awards outstanding under the 2017 Plan that are forfeited, lapsed or unexercised, and which following the effective date of the 2020 Plan are not issued under the 2017 Plan. In addition, the 2020 Plan reserve will increase on January 1, 2021 and each subsequent anniversary through 2030, by an amount equal to the lesser of (a) four percent of the shares of stock outstanding (on an as-converted basis) on the day immediately prior to the date of increase and (b) such smaller number of shares of stock as determined by our board of directors; provided, however, that no more than 11,000,000 shares of stock may be issued upon the exercise of incentive stock options. Accordingly, on January 1, 2021, the plan reserve increased by 1,747,112 shares. As of December 31, 2020, the Company had 2,184,517 shares available for future grant under the 2020 Plan.

The 2020 Plan provides for the Company to sell or issue common stock or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the board of directors and consultants of the Company under terms and provisions established by the board of directors. Under the terms of the 2020 Plan, options may be granted at an exercise price not less than fair market value. The Company generally grants stock-based awards with service conditions. Options granted typically vest over a four-year period but may be granted with different vesting terms.

Following the Company’s IPO and in connection with the effectiveness of the Company’s 2020 Plan, the 2017 Plan terminated and no further awards will be granted under that plan. However, all outstanding awards under the 2017 Plan will continue to be governed by their existing terms.

Stock Option Activity

The following summarizes option activity (in thousands, except share amounts):


	Number of Options	Weighted- Average Exercise Price		Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—December 31, 2017	472,991	$	0.36	9.40	$	360
Granted	836,992	0.64
Exercised	(918,885)	0.42
Balance—December 31, 2018	391,098	0.82		9.56	334
Granted	2,421,221	3.59
Exercised	(250,865)	1.02
Forfeited	(31,863)	0.58
Expired	(13,121)	0.58
Balance—December 31, 2019	2,516,470	3.47		9.44	7,673
Granted	1,368,825	26.83
Exercised	(197,228)	2.67
Forfeited	(32,122)	22.82
Balance—December 31, 2020	3,655,945	12.09		8.78	59,274
Exercisable—12/31/2020(1)	2,034,061	7.33		8.54	42,314

______________

(1)Options exercisable includes early exercisable options.

The aggregate intrinsic value is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock as of December 31, 2020. As of December 31, 2019, prior to the Company's IPO, the estimated fair value of the Company's common stock was determined by the board of directors.

The intrinsic value of options exercised for the year ended December 31, 2020 was $3.6 million.

The total grant-date fair value of the options vested during the year ended December 31, 2020 was $2.8 million. The weighted-average grant-date fair value of employee options granted during the year ended December 31, 2020 was $18.16.

Restricted Stock Unit Activity

The following table summarizes information regarding our RSUs:


	Number of Units	Weighted-Average Grant Date Fair Value
Balance—December 31, 2019	—	—
Granted	163,560	$	27.26
Vested	—	—
Forfeited	(630)	27.61
Unvested Balance—December 31, 2020	162,930	27.26

The grant date fair value of an RSU equals the closing price of our common stock on the grant date. RSUs generally vest equally over four years. There were no RSU grants prior to January 1, 2020.

Stock-Based Compensation Expense

Stock-based compensation expense included in the statements of operations and comprehensive loss was as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Research and development	$	3,503	$	351	$	44
General and administrative	4,440		473		107
Total stock-based compensation expense	$	7,943	$	824	$	151

As of December 31, 2020, there was $23.2 million of total unrecognized compensation cost related to unvested options that are expected to vest, which is expected to be recognized over a weighted-average period of 3.2 years. As of December 31, 2020, there was $3.6 million of total unrecognized compensation cost related to RSUs that is expected to vest, which is expected to be recognized over a weighted-average period of 3.6 years.

In determining the fair value of the stock options granted, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment.

Fair value of common stock—For options granted prior to IPO in the year ended December 31, 2019, given the absence of a public trading market, the Company’s board of directors with input from management considered numerous objective and subjective factors to determine the fair value of common stock. The factors included, but were not limited to: (i) third-party valuations of the Company’s common stock; (ii) the Company’s stage of development; (iii) the status of research and development efforts; (iv) the rights, preferences and privileges of the Company’s convertible preferred stock relative to those of the Company’s common stock; (v) the Company’s operating results and financial condition, including the Company’s levels of available capital resources; and (vi) equity market conditions affecting comparable public companies; (vii) general U.S. market conditions; and (viii) the lack of marketability of the Company’s common stock. For options granted after IPO, the Company uses its closing stock price as reported on Nasdaq on the grant date for the fair value of its stock.

Expected Term—The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding. The Company used the simplified method (based on the mid-point between the vesting date and the end of the contractual term) to determine the expected term.

Expected Volatility—Since the Company does not have sufficient trading history for its common stock, the expected volatility was estimated based on the average historical volatilities for comparable publicly traded pharmaceutical companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, stage in the life cycle and area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option.

Dividend Yield—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

The fair value of stock option awards granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:

Year Ended December 31,

2020

2019

2018

Expected term (in years)

5.5 – 6.8

5.1 – 6.6

5.9 – 6.1

Expected volatility

78.4 – 80.8%

68.6 – 72.5%

68.2 –72.4%

Risk-free interest rate

0.3 – 1.4%

1.6 – 2.6%

2.7 – 2.9%

Dividend yield

—%

Early Exercise of Employee Options

The terms of the 2017 and 2020 Plans permit certain option holders to exercise options before their options are vested, subject to certain limitations. Upon early exercise, the awards become subject to a restricted stock agreement. The shares of restricted stock granted upon early exercise of the options are subject to the same vesting provisions in the original stock option awards. Shares issued as a result of early exercise that have not vested are subject to repurchase by the Company upon termination of the purchaser’s employment, at the price paid by the purchaser. While such shares have been issued, they are not considered outstanding for accounting purposes until they vest and are therefore excluded from shares used in determining loss per share until the repurchase right lapses and the shares are no longer subject to the repurchase feature. The liability is reclassified into common stock and additional paid-in capital as the shares vest and the repurchase right lapses. Accordingly, the Company has recorded the unvested portion of the exercise proceeds of $258,000 and $409,000 as a liability from the early exercise in the accompanying balance sheets as of December 31, 2020 and 2019, respectively. As of December 31, 2020 and 2019, there were $176,000 and $225,000 recorded in accrued liabilities, respectively, and $82,000 and $184,000 recorded in other long-term liabilities, respectively related to shares that were subject to repurchase.

Founder Awards

In August 2016, the Company issued 1,187,738 shares of restricted common stock to founders of which 1,102,903 shares vest under a service condition and 84,835 shares vest under a performance condition. The shares were issued under the terms of the respective restricted stock purchase agreements, or the Stock Purchase Agreement, and unvested shares were subject to repurchase by the Company at the original purchase price per share upon the holder’s termination of his relationship with the Company. The restricted shares were not considered outstanding for accounting purposes until they vested and are therefore excluded from shares used in determining loss per share until the repurchase right lapses and the shares are no longer subject to the repurchase feature. One-fourth of the 1,102,903 shares of restricted common stock were vested on the first-anniversary date and the remaining 827,177 shares will vest on a monthly basis thereafter. In July 2018, performance conditions prescribed by the Stock Purchase Agreement were met and 84,835 shares of the restricted common stock were fully vested. As of December 31, 2019, 1,049,875 shares subject to the award had vested, and an additional 137,863 shares vested during the year ended December 31, 2020. As of December 31, 2020, all shares of restricted stock subject to the award had been vested.

2020 Employee Stock Purchase Plan

The Company adopted the 2020 Employee Stock Purchase Plan, or the ESPP, which became effective on January 30, 2020 in connection with the IPO. The ESPP is designed to allow the Company’s eligible employees to purchase shares of the Company’s common stock, at semi-annual intervals, with their accumulated payroll deductions. Under the ESPP, participants are offered the option to purchase shares of the Company’s common stock at a discount during a series of successive offering periods. The option purchase price will be the lower of 85% of the closing trading price per share of the Company’s common stock on the first trading date of an offering period in which a participant is enrolled or 85% of the closing trading price per share on the purchase date, which will occur on the last trading day of each offering period.

The ESPP is intended to qualify under Section 423 of the U.S. Internal Revenue Service Code of 1986, as amended. The maximum number of the Company’s common stock which will be authorized for sale under the ESPP is equal to the sum of (a) 351,000 shares of common stock and (b) an annual increase on the first day of each year beginning in 2021 and ending in 2030, equal to the lesser of (i) 1% of the shares of common stock outstanding (on an as-converted basis) on the last day of the immediately preceding fiscal year and (ii) such number of shares of common stock as determined by the Company’s board of directors; provided, however, no more than 5,265,000 shares of the Company’s common stock may be issued under the ESPP. Accordingly, on January 1, 2021, the ESPP reserve increased by 436,778 shares.

The Company commenced an offering period on January 31, 2020, which ended on May 31, 2020, and resulted in 19,862 shares of stock being issued under the ESPP. The Company also commenced an offering period on June 1, 2020, which ended on November 30, 2020, and resulted in 14,326 shares of stock being issued under the ESPP. In addition, the Company commenced an offering period on December 1, 2020, which will end on May 31, 2021. Stock-based compensation expense related to the ESPP was $346,000 for the year ended December 31, 2020.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

No provision for income taxes was recorded for the years ended December 31, 2020, 2019 and 2018. The Company has incurred NOLs only in the United States since its inception. The Company has not reflected any benefit of such NOL carryforwards in the financial statements.

Reconciliation of income tax computed at federal statutory rates to the reported provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Tax provision at U.S. statutory rate	$	(28,493)	$	(8,819)	$	(4,043)
State income taxes, net of federal benefit	(9,213)		(2,786)		(1,224)
Research and development tax and other credits	(2,413)		(655)		(265)
Change in valuation allowance	30,708		9,598		4,418
Uncertain tax positions	8,801		2,604		911
Permanent differences	616		58		219
Fair value adjustment	—		—		(16)
Other	(6)		—		—
Provision for income tax	$	—	$	—	$	—

Significant components of the Company’s deferred income taxes were as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	38,196	$	11,457
Intangibles	1,777		1,937
Research and development tax credits	3,370		1,092
Accruals and reserves	1,041		355
Right-of-use liability	1,274		79
Stock-based compensation	1,122		62
Property and equipment	—		2
Gross deferred tax assets	$	46,780	$	14,984

Deferred tax liabilities:
Property and equipment	$	(299)	$	—
Right-of-use asset	(859)		(68)
Gross deferred tax liabilities	$	(1,158)	$	(68)

Net deferred tax assets	$	45,622	$	14,916
Less valuation allowance	(45,622)		(14,916)
Total deferred tax assets	$	—	$	—

Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Due to the lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by approximately $30.7 million and $9.6 million during the years ended December 31, 2020 and 2019, respectively.

The Company has NOL carryforwards for federal, California and other state income tax purposes of approximately $180.7 million, $180.8 million and $3.2 million, respectively, as of December 31, 2020. Of the federal NOLs, $3.5 million originated before the 2018 tax year and will expire beginning in 2036. Under the Tax Cuts and Jobs Act of 2017, the remaining $177.2 million of NOLs generated after December 31, 2017 will be carried forward indefinitely.

On March 27, 2020, the CARES Act was signed into law in response to the economic challenges facing US businesses. Under the CARES Act, the Internal Revenue Code was amended to allow for federal NOL carrybacks for five years to offset previous years income, or can be carryforward indefinitely to offset 100% of taxable income for the tax year 2020 and 80% of taxable income for tax years 2021 and thereafter. As of the date the financial statements were available to be issued, the state NOL carryforwards, if not utilized, will expire beginning in 2030.

As of December 31, 2020, the Company also had federal and California research and development tax credit carryforwards of $6.4 million and $1.4 million, respectively. The federal research and development tax credit carryforwards will begin to expire in 2036. The California research and development tax credit carryforwards are available indefinitely.

Federal and California tax laws impose significant restrictions on the utilization of NOL carryforwards in the event of a change in ownership of the Company, as defined by Internal Revenue Code Section 382 and 383. The Company has not completed a formal study to determine the limitations on their tax attributes due to change in ownership and may have limitations on the utilization of NOL carryforwards, credit carryforwards, or other tax attributes due to ownership changes.

Uncertain Tax Benefits

No liability related to uncertain tax positions is recorded on the financial statements related to uncertain tax positions.

The following table summarizes the activity related to the unrecognized benefits (in thousands):


	Year Ended December 31,
	2020		2019		2018
Beginning balance	$	6,448	$	2,241	$	441
Increases related to tax positions taken during a prior year	5		4		—
Increases related to tax positions taken during the current year	13,821		4,203		1,800
Ending balance	$	20,274	$	6,448	$	2,241

The reversal of the uncertain tax benefits would not affect the effective tax rate to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. The Company does not anticipate any significant changes to unrecognized tax benefits over the next 12 months.

Income tax returns are filed in the U.S. and California. The Company is not currently under audit by the Internal Revenue Service or similar state or local authorities. The years 2016 and forward remain open to examination by the domestic taxing jurisdictions to which the Company is subject. Due to NOL carryforwards, all years effectively remain open to income tax examination by the domestic taxing jurisdictions in which the Company files tax returns.

Included in unrecognized tax benefits of $20.3 million at December 31, 2020 was $16.7 million of tax benefits that, if recognized, would reduce our annual effective tax rate, subject to valuation allowance. We do not expect that there will be a significant change in the unrecognized tax benefits over the next 12 months.

We are subject to taxation in the United States and state jurisdictions where applicable. Our tax years for 2016 and forward are subject to examination by the U.S. tax authorities and our tax years for 2016 and forward are subject to examination by the California tax authorities due to carryforward of unutilized NOLs and research and development credits.

It is our practice to recognize interest and/or penalties related to income tax matters in income tax expense. For the years ended December 31, 2020, 2019 and 2018, we have not recognized any interest or penalties related to income taxes.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Net Loss Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

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 December 31,
	2020	2019	2018
Convertible preferred stock on an as-converted basis	—	24,385,388	16,262,425
Stock options to purchase common stock	3,655,945	2,516,470	391,098
Early exercised options subject to future vesting	339,385	621,053	644,166
RSU's subject to future vesting	162,930	—	—
ESPP shares subject to future issuance	3,733	—	—
Restricted stock subject to future vesting	—	137,863	413,589
Total	4,161,993	27,660,774	17,711,278

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

The following table contains unaudited financial information on a quarterly basis for 2020 and 2019. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period.


	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in thousands, except per share amounts)
Year Ended December 31, 2020
Total operating expenses	$	28,651	$	35,627	$	38,303	$	34,064
Other income, net	638		215		99		15
Net loss	(28,013)		(35,412)		(38,204)		(34,049)
Net loss per share, basic and diluted	$	(1.15)	$	(0.94)	$	(1.01)	$	(0.79)


	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in thousands, except per share amounts)
Year Ended December 31, 2019
Total operating expenses	$	6,952	$	8,538	$	14,648	$	12,994
Other income, net	294		248		168		426
Net loss	(6,658)		(8,290)		(14,480)		(12,568)
Net loss per share, basic and diluted	$	(4.08)	$	(4.69)	$	(7.56)	$	(6.13)

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On February 5, 2021, the Company completed a public offering of 6,325,000 shares of common stock at an offering price of $35.00 per share, which included 825,000 shares sold pursuant to the underwriters' full exercise of their option to purchase additional shares, receiving approximately $207.4 million in aggregate net proceeds, after deducting underwriting discounts, commissions and estimated offering expenses.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s financial statements have been prepared in accordance with United States generally accepted accounting principles (U.S. GAAP).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates such estimates and assumptions for continued reasonableness. In particular, management makes estimates with respect to accruals for research and development activities, fair value of common stock and convertible preferred stock (prior to the IPO completed in January 2020), stock-based compensation expense and income taxes. Appropriate adjustments, if any, to the estimates used are made prospectively based upon such periodic evaluation. Actual results could differ from those estimates.
Segments	Segments To date, the Company has viewed its financial information on an aggregate basis for the purposes of evaluating financial performance and allocating the Company’s resources. Accordingly, the Company has determined that it operates in one segment.
Cash, Cash Equivalents and Restricted Cash	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of money market funds, commercial paper, and U.S. Treasury securities. Restricted Cash As of December 31, 2020, the Company held $1.5 million of restricted cash as collateral for a letter of credit related to our amended office space lease. As of December 31, 2019, the Company did not hold any restricted cash.
Marketable Securities	Marketable Securities Marketable securities consist of investment grade short to intermediate-term fixed income investments that have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments in fixed income securities at the time of purchase. Available-for-sale securities with original maturities beyond three months at the date of purchase are classified as current based on their availability for use in current operations. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. Realized gains and losses as well as credit losses, if any, on marketable securities are included in other income, net. The Company evaluated the underlying credit quality and credit ratings of the issuers during the period.
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash to the extent recorded on the balance sheets. Management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
Fair Value Measurement	Fair Value Measurement The Company’s financial instruments, in addition to those presented in Note 3, include cash equivalents, accounts payable and accrued liabilities. The carrying amount of cash equivalents, accounts payable and accrued liabilities approximate their fair values due to their short maturities. Assets and liabilities recorded at fair value on a recurring basis on the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Property and Equipment	Property and EquipmentProperty and equipment are stated at cost less accumulated depreciation. Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets which range from three to five years. Leasehold improvements are depreciated on a straight-line basis over the shorter of their estimated useful lives or lease terms. Maintenance and repairs are expensed as incurred. The Company reviews the carrying values of its property and equipment for possible impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.
Leases	Leases The Company determines if an arrangement is or contains a lease at inception. Right-of-use (ROU) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases along with the initial measurement and recognition of the associated ROU assets and lease liabilities is performed at the lease commencement date. The measurement of lease liabilities is based on the present value of lease payments over the lease term. The Company uses its incremental borrowing rate, based on the information available at commencement date, to determine the present value of lease payments when its leases do not provide an implicit rate. The Company uses the implicit rate when readily determinable. The ROU asset is based on the measurement of the lease liability, includes any lease payments made prior to or on lease commencement and is adjusted for lease incentives and initial direct costs incurred, as applicable. Lease expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company considers a lease term to be the non-cancelable period that it has the right to use the underlying asset, including any periods where it is reasonably assured the Company will exercise the option to extend the contract. Periods covered by an option to extend are included in the lease term if the lessor controls the exercise of that option. The Company’s lease agreements includes lease and non-lease components and the Company has elected to not separate such components for all classes of assets. Further, the Company elected the short-term lease exception policy, permitting it to not apply the recognition requirements of this standard to leases with terms of 12 months or less (short-term leases) for all classes of assets.
Preclinical and Clinical Accruals and Costs	Preclinical and Clinical Accruals and CostsThe Company records accrued liabilities for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical studies, clinical trials and contract manufacturing activities. These costs are a significant component of the Company’s research and development expenses. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers under the service agreements. The Company makes significant judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities.
Convertible Preferred Stock	Convertible Preferred StockPrior to its IPO, the Company classified its outstanding convertible preferred stock outside of stockholders’ equity (deficit) on its balance sheets as the requirements of triggering a deemed liquidation event, as defined within its amended and restated certificate of incorporation, were not entirely within the Company’s control. In the event of such a deemed liquidation event, the proceeds from the event were to be distributed in accordance with the liquidation preferences, provided that the holders of convertible preferred stock had not converted their shares into common stock. The Company recorded the issuance of convertible preferred stock at the issuance price less related issuance costs. The Company did not adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty as to whether or when a deemed liquidation event may have occurred.
Research and Development	Research and Development Research and development expenses include costs directly attributable to the conduct of research and development programs, including the cost of salaries, payroll taxes, employee benefits, license fees, stock-based compensation expense, materials, supplies, and the cost of services provided by outside contractors. All costs associated with research and development are expensed as incurred. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods are received or services are rendered. Such payments are evaluated for current or long-term classification based on when they will be realized. The Company has entered into and may continue to enter into, license agreements to access and utilize certain technology. In each case, the Company evaluates if the license agreement results in the acquisition of an asset or a business. To date, none of the Company’s license agreements have been considered an acquisition of a business. For asset acquisitions, the upfront payments to acquire such licenses, as well as any future milestone payments made before product approval that do not meet the definition of a derivative, are immediately recognized as research and development expense when paid or become payable, provided there is no alternative future use of the rights in other research and development projects.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for share-based payments at fair value. The fair value of stock options is measured using the Black-Scholes option-pricing model. For share-based awards that vest subject to the satisfaction of a service requirement, the fair value measurement date for such awards is the date of grant and the expense is recognized on a straight-line basis, over the expected vesting period. For share-based awards that vest subject to a performance condition, the Company will recognize compensation cost for awards if and when the Company concludes that it is probable that the awards with a performance condition will be achieved on an accelerated attribution method. The Company accounts for forfeitures as they occur.
Income Taxes	Income Taxes Income taxes are accounted for using the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of enactment. The Company records a valuation allowance to reduce deferred tax assets to an amount for which realization is more likely than not. Due to the Company’s historical operating performance and the recorded cumulative net losses in prior fiscal periods, the net deferred tax assets have been fully offset by a valuation allowance. The Company recognizes the tax benefit from an uncertain tax position if it is more likely than not that the tax position will be sustained upon examination by the tax authorities, based on the merits of the position. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties incurred in relation to the unrecognized tax benefits. The United States Congress enacted the Families First Coronavirus Response Act (FFCR Act) on March 18, 2020 and the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) on March 27, 2020. The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the U.S. economy and fund a nationwide effort to curtail the effect of COVID-19. The FFCR Act and CARES Act include numerous tax-related provisions including modifications to the limitations on business interest expense and net operating losses (NOLs), certain refundable employee retention credits, as well as a payment delay of employer payroll taxes in 2020 after the date of enactment. On June 29, 2020, the California State Assembly Bill 85 (Trailer Bill) was enacted which suspends the use of California NOL deductions and certain tax credits, including research and development credits, for the 2020, 2021, and 2022 tax years. The Company does not expect the FFCR Act, CARES Act or Trailer Bill to have a material impact on the Company’s financial statements.
Variable Interest Entities	Variable Interest Entities The Company reviews agreements it enters into with third-party entities, pursuant to which the Company may have a variable interest in the entity, in order to determine if the entity is a variable interest entity (VIE). If the entity is a VIE, the Company assesses whether or not it is the primary beneficiary of that entity. In determining whether the Company is the primary beneficiary of an entity, the Company applies a qualitative approach that determines whether it has both (i) the power to direct the economically significant activities of the entity and (ii) the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. If the Company determines it is the primary beneficiary of a VIE, it consolidates that VIE into the Company’s financial statements. The Company’s determination about whether it should consolidate such VIEs is made continuously as changes to existing relationships or future transactions may result in a consolidation or deconsolidation event. The Company currently does not consolidate any VIEs.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive. Shares of common stock subject to repurchase are excluded from the weighted-average shares.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it is (i) no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU No. 2018-13, which removes, modifies, and adds various disclosure requirements on fair value measurements in Topic 820. ASU No. 2018-13 is effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted-average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company early adopted this standard as of January 1, 2020, and it did not have a material impact on its financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, or ASU No. 2016-13. This update requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations now include forward-looking information in the determination of their credit loss estimates. Many of the previous loss estimation techniques are still permitted, although the inputs to those techniques have changed to reflect the full amount of expected credit losses. In addition, this update amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The Company early adopted this standard as of January 1, 2020, and it did not have a material impact on its financial statements. There was no impact on the Company's financial statements from credit losses for the year ended December 31, 2020.In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740), or ASU No. 2019-12, which amends the existing guidance relating to the accounting for income taxes. This standard is intended to simplify the accounting for income taxes by removing certain exceptions to the general principles of accounting for income taxes and to improve the consistent application of GAAP for other areas of accounting for income taxes by clarifying and amending existing guidance. The standard is effective for public business entities for fiscal years beginning after December 15, 2020, and interim periods therein. Early adoption is permitted. An entity that elects early adoption in an interim period should reflect any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an entity that elects early adoption should adopt all the amendments in the same period. The Company early adopted this guidance as of January 1, 2020, and it did not have a material impact on its financial statements.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value of Assets Measured on a Recurring Basis

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	December 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	65,082	$	—	$	—	$	65,082
Commercial paper	—		45,518		—		45,518

U.S. Treasury securities	173,841		—		—		173,841
Total assets	$	238,923	$	45,518	$	—	$	284,441


	December 31, 2019
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds(1)	$	43,558	$	—	$	—	$	43,558
Commercial paper	—		44,689		—		44,689
U.S. Treasury securities	13,018		—		—		13,018
Total assets	$	56,576	$	44,689	$	—	$	101,265

______________

(1)This balance includes cash requirements settled on a nightly basis.

Summary of Marketable Securities

The following table summarizes the estimated value of the Company’s cash, cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands):


	December 31, 2020
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:

Money market funds(1)	$	65,082	$	—	$	—	$	65,082

Total cash and cash equivalents	$	65,082	$	—	$	—	$	65,082
Marketable securities:
Commercial paper	$	45,518	—		—		$	45,518

U.S. Treasury securities	173,843		7		(9)		173,841
Total marketable securities	$	219,361	$	7	$	(9)	$	219,359

______________

(1)This balance includes cash requirements settled on a nightly basis.


	December 31, 2019
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:
Commercial paper	$	11,780	$	—	$	—	$	11,780
Money market funds(1)	43,558		—		—		43,558
U.S. Treasury securities	7,998		—		—		7,998
Total cash and cash equivalents	$	63,336	$	—	$	—	$	63,336
Marketable securities:
Commercial paper	$	32,909	$	—	$	—	$	32,909
U.S. Treasury securities	5,021		—		(1)		5,020
Total marketable securities	$	37,930	$	—	$	(1)	$	37,929

______________

(1)This balance includes cash requirements settled on a nightly basis.

Summary of Cash and Cash Equivalents

The following table summarizes the estimated value of the Company’s cash, cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands):


	December 31, 2020
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:

Money market funds(1)	$	65,082	$	—	$	—	$	65,082

Total cash and cash equivalents	$	65,082	$	—	$	—	$	65,082
Marketable securities:
Commercial paper	$	45,518	—		—		$	45,518

U.S. Treasury securities	173,843		7		(9)		173,841
Total marketable securities	$	219,361	$	7	$	(9)	$	219,359

______________

(1)This balance includes cash requirements settled on a nightly basis.


	December 31, 2019
	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
Cash and cash equivalents:
Commercial paper	$	11,780	$	—	$	—	$	11,780
Money market funds(1)	43,558		—		—		43,558
U.S. Treasury securities	7,998		—		—		7,998
Total cash and cash equivalents	$	63,336	$	—	$	—	$	63,336
Marketable securities:
Commercial paper	$	32,909	$	—	$	—	$	32,909
U.S. Treasury securities	5,021		—		(1)		5,020
Total marketable securities	$	37,930	$	—	$	(1)	$	37,929

______________

(1)This balance includes cash requirements settled on a nightly basis.

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):


	December 31, 2020		December 31, 2019
Prepaid clinical trial costs	$	4,865	$	2,998
Tax credits	510		145
Prepaid insurance	249		62
Deferred financing costs	—		1,747
Other prepaid expenses and current assets	1,219		257
Total prepaid expenses and other current assets	$	6,843	$	5,209

Summary of Accrued Liabilities

Accrued liabilities consist of the following (in thousands):


	December 31, 2020		December 31, 2019
Clinical trial accruals	$	9,754	$	1,497
Accrued compensation	4,434		1,379
Early exercise liability, current	176		225
Accrued expenses and other current liabilities	1,098		553
Total accrued liabilities	$	15,462	$	3,654

Property and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment, net consists of the following (in thousands):


		December 31,
	Useful life (in years)	2020		2019
Computer hardware	3	$	286	$	80
Furniture and fixtures	5	230		60
Construction in process		298		—
Leasehold improvements		1,280		155
Property and equipment, gross		2,094		295
Less accumulated depreciation		(78)		(68)
Property and equipment, net		$	2,016	$	227

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Operating Lease Payments

The minimum annual rental payments of the Company’s operating lease liability as of December 31, 2020 are as follows (in thousands):


	Amounts
2021	$	114
2022	781
2023	965
2024	995
2025	1,024
Thereafter	2,794
Total minimum lease payments	$	6,673
Less: Amounts representing interest	(1,709)

Present value of lease payments	$	4,964

Operating lease liability, noncurrent	4,964
Total operating lease liability	$	4,964

Operating Lease Supplemental Cash Flow and Additional Information

The following information represents supplemental disclosure for the statement of cash flows related to the Company’s operating lease (in thousands):


	December 31, 2020
Cash flows from operating activities
Cash paid for amounts included in the measurement of lease liabilities	$	192

The following summarizes additional information related to the operating lease:


	December 31, 2020
Weighted-average remaining lease term (in years)	7.6
Weighted-average discount rate	7.0	%

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Convertible Preferred Stock

Convertible preferred stock as of December 31, 2019 consisted of the following (in thousands, except share amounts):


Convertible Preferred Stock	Shares Authorized	Shares Issued and Outstanding	Net Carrying Value		Liquidation Preference
Series A	13,800,000	6,897,575	$	14,340	$	13,800
Series B	18,736,270	9,364,850	57,912		58,000
Series C	16,251,628	8,122,963	94,239		94,500
Total	48,787,898	24,385,388	$	166,491	$	166,300

Components of Shares of Stock for Issuance

The Company reserved the following shares of common stock for issuance as follows:


	December 31,
	2020	2019
Convertible preferred stock outstanding	—	24,385,388
Options issued and outstanding	3,655,945	2,516,470
Common stock awards available for grant under employee benefit plans	2,501,329	1,550,150
Restricted stock units outstanding	162,930	—
Total common stock reserved	6,320,204	28,452,008

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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+ Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock Option Activity

The following summarizes option activity (in thousands, except share amounts):


	Number of Options	Weighted- Average Exercise Price		Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—December 31, 2017	472,991	$	0.36	9.40	$	360
Granted	836,992	0.64
Exercised	(918,885)	0.42
Balance—December 31, 2018	391,098	0.82		9.56	334
Granted	2,421,221	3.59
Exercised	(250,865)	1.02
Forfeited	(31,863)	0.58
Expired	(13,121)	0.58
Balance—December 31, 2019	2,516,470	3.47		9.44	7,673
Granted	1,368,825	26.83
Exercised	(197,228)	2.67
Forfeited	(32,122)	22.82
Balance—December 31, 2020	3,655,945	12.09		8.78	59,274
Exercisable—12/31/2020(1)	2,034,061	7.33		8.54	42,314

______________

(1)Options exercisable includes early exercisable options.

Restricted Stock Unit Activity

The following table summarizes information regarding our RSUs:


	Number of Units	Weighted-Average Grant Date Fair Value
Balance—December 31, 2019	—	—
Granted	163,560	$	27.26
Vested	—	—
Forfeited	(630)	27.61
Unvested Balance—December 31, 2020	162,930	27.26

Stock-Based Compensation Expense

Stock-based compensation expense included in the statements of operations and comprehensive loss was as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Research and development	$	3,503	$	351	$	44
General and administrative	4,440		473		107
Total stock-based compensation expense	$	7,943	$	824	$	151

Assumptions in Calculating Stock Option Awards

The fair value of stock option awards granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:

Year Ended December 31,

2020

2019

2018

Expected term (in years)

5.5 – 6.8

5.1 – 6.6

5.9 – 6.1

Expected volatility

78.4 – 80.8%

68.6 – 72.5%

68.2 –72.4%

Risk-free interest rate

0.3 – 1.4%

1.6 – 2.6%

2.7 – 2.9%

Dividend yield

—%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

Reconciliation of income tax computed at federal statutory rates to the reported provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2020		2019		2018
Tax provision at U.S. statutory rate	$	(28,493)	$	(8,819)	$	(4,043)
State income taxes, net of federal benefit	(9,213)		(2,786)		(1,224)
Research and development tax and other credits	(2,413)		(655)		(265)
Change in valuation allowance	30,708		9,598		4,418
Uncertain tax positions	8,801		2,604		911
Permanent differences	616		58		219
Fair value adjustment	—		—		(16)
Other	(6)		—		—
Provision for income tax	$	—	$	—	$	—

Schedule of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred income taxes were as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	38,196	$	11,457
Intangibles	1,777		1,937
Research and development tax credits	3,370		1,092
Accruals and reserves	1,041		355
Right-of-use liability	1,274		79
Stock-based compensation	1,122		62
Property and equipment	—		2
Gross deferred tax assets	$	46,780	$	14,984

Deferred tax liabilities:
Property and equipment	$	(299)	$	—
Right-of-use asset	(859)		(68)
Gross deferred tax liabilities	$	(1,158)	$	(68)

Net deferred tax assets	$	45,622	$	14,916
Less valuation allowance	(45,622)		(14,916)
Total deferred tax assets	$	—	$	—

Schedule of Unrecognized Tax Benefits Roll Forward

The following table summarizes the activity related to the unrecognized benefits (in thousands):


	Year Ended December 31,
	2020		2019		2018
Beginning balance	$	6,448	$	2,241	$	441
Increases related to tax positions taken during a prior year	5		4		—
Increases related to tax positions taken during the current year	13,821		4,203		1,800
Ending balance	$	20,274	$	6,448	$	2,241

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Potentially Antidilutive Shares Excluded from the 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 December 31,
	2020	2019	2018
Convertible preferred stock on an as-converted basis	—	24,385,388	16,262,425
Stock options to purchase common stock	3,655,945	2,516,470	391,098
Early exercised options subject to future vesting	339,385	621,053	644,166
RSU's subject to future vesting	162,930	—	—
ESPP shares subject to future issuance	3,733	—	—
Restricted stock subject to future vesting	—	137,863	413,589
Total	4,161,993	27,660,774	17,711,278

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (Unaudited)


	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in thousands, except per share amounts)
Year Ended December 31, 2020
Total operating expenses	$	28,651	$	35,627	$	38,303	$	34,064
Other income, net	638		215		99		15
Net loss	(28,013)		(35,412)		(38,204)		(34,049)
Net loss per share, basic and diluted	$	(1.15)	$	(0.94)	$	(1.01)	$	(0.79)


	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in thousands, except per share amounts)
Year Ended December 31, 2019
Total operating expenses	$	6,952	$	8,538	$	14,648	$	12,994
Other income, net	294		248		168		426
Net loss	(6,658)		(8,290)		(14,480)		(12,568)
Net loss per share, basic and diluted	$	(4.08)	$	(4.69)	$	(7.56)	$	(6.13)

Organization and Description of Business (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	Feb. 05, 2021 USD ($) $ / shares shares	Oct. 06, 2020 USD ($) $ / shares shares	Feb. 04, 2020 USD ($) $ / shares shares	Jan. 17, 2020	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Feb. 05, 2020 shares	Dec. 31, 2017 shares
Subsidiary, Sale of Stock [Line Items]
Reverse stock split ratio for capital stock				0.4998
Proceeds from initial public offering, net of issuance costs					$ 168,642	$ 0	$ 0
Convertible preferred stock, shares outstanding (in shares) \| shares					0	24,385,388	16,262,425	0	3,740,791
Proceeds from issuance of common stock					$ 128,360	$ 0	$ 0
Accumulated deficit					(201,950)	(66,272)
Cash, cash equivalents, restricted cash and marketable securities					$ 286,000	$ 101,300
Common Stock
Subsidiary, Sale of Stock [Line Items]
Stock price (in USD per share) \| $ / shares		$ 25.00
Common Stock \| Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Stock price (in USD per share) \| $ / shares	$ 35.00
IPO
Subsidiary, Sale of Stock [Line Items]
Proceeds from initial public offering, net of issuance costs			$ 167,200
IPO \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares			10,781,250
Stock price (in USD per share) \| $ / shares			$ 17.00
Underwriters' option \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares			1,406,250
Underwriters' option \| Common Stock \| Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares	825,000
Secondary equity public offering
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock		$ 93,400
Secondary equity public offering \| Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock	$ 180,300
Secondary equity public offering \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares		4,000,000
Private placement
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock		$ 35,000
Private placement \| Common Stock
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares		1,400,000
Third equity offering \| Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock	$ 207,400
Third equity offering \| Common Stock \| Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares) \| shares	6,325,000

Summary of Significant Accounting Policies (Details)	1 Months Ended	12 Months Ended
Summary of Significant Accounting Policies (Details)	Feb. 29, 2020 shares	Dec. 31, 2020 USD ($) segment shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Class of Stock [Line Items]
Number of operating segments (segment) \| segment		1
Restricted cash		$ 1,542,000	$ 0
Allowance for credit loss		0	0
Unrealized gains (losses)		(2,000)	(1,000)
Realized gains (losses) on investments		0	0
Tangible asset impairment charges		0	0
Unrecognized tax benefits, income tax penalties and interest expense		$ 0	$ 0	$ 0
Minimum
Class of Stock [Line Items]
Useful life (in years)		3 years
Maximum
Class of Stock [Line Items]
Useful life (in years)		5 years
Common Stock
Class of Stock [Line Items]
Shares issued as a result of conversion of promissory notes (in shares) \| shares	24,385,388	24,385,388

Fair Value Measurements - Fair Value of Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 65,082	$ 63,336
Total assets	284,441	101,265
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	45,518	44,689
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	173,841	13,018
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	65,082	43,558
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	238,923	56,576
Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	0	0
Level 1 \| U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	173,841	13,018
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	65,082	43,558
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	45,518	44,689
Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	45,518	44,689
Level 2 \| U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	0	0
Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	0	0
Level 3 \| U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents and debt securities, available for sale	0	0
Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 0	$ 0

Fair Value Measurements - Estimated Value of Cash and Cash Equivalents and Marketable Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 65,082,000	$ 63,336,000
Cash and cash equivalents, estimated fair value	65,082,000	63,336,000
Debt Securities, Available-for-sale [Line Items]
Amortized cost	219,361,000	37,930,000
Unrealized gains	7,000	0
Unrealized losses	(9,000)	(1,000)
Estimated fair value	219,359,000	37,929,000
Realized gains (losses) on investments	0	0
Unrealized loss on marketable securities	0	0
Allowance for credit loss	0	0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized cost	45,518,000	32,909,000
Unrealized gains	0	0
Unrealized losses	0	0
Estimated fair value	45,518,000	32,909,000
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized cost	173,843,000	5,021,000
Unrealized gains	7,000	0
Unrealized losses	(9,000)	(1,000)
Estimated fair value	173,841,000	5,020,000
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		11,780,000
Cash and cash equivalents, estimated fair value		11,780,000
Money market funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	65,082,000	43,558,000
Cash and cash equivalents, estimated fair value	$ 65,082,000	43,558,000
U.S. Treasury securities
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		7,998,000
Cash and cash equivalents, estimated fair value		$ 7,998,000

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Prepaid clinical trial costs	$ 4,865	$ 2,998
Tax credits	510	145
Prepaid insurance	249	62
Deferred financing costs	0	1,747
Other prepaid expenses and current assets	1,219	257
Total prepaid expenses and other current assets	$ 6,843	$ 5,209

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Clinical trial accruals	$ 9,754	$ 1,497
Accrued compensation	4,434	1,379
Early exercise liability, current	176	225
Accrued expenses and other current liabilities	1,098	553
Total accrued liabilities	$ 15,462	$ 3,654

Property and Equipment, net - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,094	$ 295
Less accumulated depreciation	(78)	(68)
Property and equipment, net	$ 2,016	227
Computer hardware
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Property and equipment, gross	$ 286	80
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Property and equipment, gross	$ 230	60
Construction in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	298	0
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,280	$ 155

Property and Equipment, net - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation	$ 122,000	$ 68,000	$ 0

License Agreements - AstraZeneca (Details) - USD ($)	1 Months Ended			12 Months Ended
License Agreements - AstraZeneca (Details) - USD ($)	Aug. 31, 2019	Sep. 30, 2018	Jul. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AstraZeneca
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement, cash payment	$ 2,000,000.0		$ 1,000,000.0	$ 0	$ 2,000,000.0	$ 4,000,000.0
Maximum milestone payments for licensed products				12,500,000
Maximum milestone payments for net worldwide sales				$ 15,000,000.0
Series B
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Preferred stock issued (in shares)		9,364,850				8,880,462
Preferred stock issued						$ 54,912,000
Series B \| AstraZeneca
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Preferred stock issued (in shares)			484,388
Preferred stock issued			$ 3,000,000.0

License Agreements - Hengrui (Details) - Hengrui - USD ($)	1 Months Ended		12 Months Ended
	Dec. 31, 2019	Jan. 31, 2018	Dec. 31, 2020
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement, cash payment	$ 1,500,000	$ 400,000	$ 0
Maximum milestone payments for licensed products			20,500,000
Maximum milestone payments for net worldwide sales			$ 200,000,000.0

License Agreements - Hawkeye (Details) - USD ($)	1 Months Ended	12 Months Ended
License Agreements - Hawkeye (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2020	Feb. 04, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Common stock, par value (in USD per share)		$ 0.0001	$ 0.0001	$ 0.0001
Hawkeye
Variable Interest Entity [Line Items]
Number of shares held in VIE (in shares)	995,000
Ownership percentage of VIE	19.90%
Collaboration agreement, threshold of proceeds from stock issuance for additional consideration	$ 5,000,000.0
Collaborative arrangement, numerator for determining additional consideration	$ 2,000,000
Payments, milestones or royalties		$ 0
Hawkeye
Variable Interest Entity [Line Items]
Common stock, par value (in USD per share)	$ 0.0001

Commitments and Contingencies - Narrative (Details)	1 Months Ended		12 Months Ended
Commitments and Contingencies - Narrative (Details)	Nov. 30, 2020 USD ($)	Apr. 30, 2020 USD ($) ft²	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Reduction in right-of-use asset upon reassessment of lease term		$ 123,000	$ 123,000	$ 0	$ 0
Restricted cash			1,542,000	0
Operating lease right-of-use asset			3,349,000	264,000
Straight-line rent expense			602,000	$ 151,000	$ 0
Variable lease cost			0
Westlake Village, California Lease Arrangement
Lessee, Lease, Description [Line Items]
Square footage of leased space (in square feet) \| ft²		22,643
Period after tenant improvements (in days)		15 days
Lease term (in months)		91 months
Renewal term		5 years
Lease term prior to termination option		67 months
Initial base rent		$ 76,000
Free rent period		1 year
Tenant improvement allowance		$ 1,250,000	$ 1,250,000
Available letter of credit		$ 1,500,000
Restricted cash	$ 1,500,000
Operating lease right-of-use asset						$ 3,600,000
Westlake Village, California Lease Arrangement \| First anniversary
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	(308,000)
Westlake Village, California Lease Arrangement \| Second anniversary
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	(308,000)
Westlake Village, California Lease Arrangement \| Third anniversary
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	(308,000)
Westlake Village, California Lease Arrangement \| Fourth anniversary
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	(308,000)
Westlake Village, California Lease Arrangement \| Fifth anniversary
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	(45,000)
Westlake Village, California Lease Arrangement \| Subsequent anniversaries
Lessee, Lease, Description [Line Items]
Decrease in restricted cash	$ 0

Commitments and Contingencies - Operating Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
2021	$ 114
2022	781
2023	965
2024	995
2025	1,024
Thereafter	2,794
Total minimum lease payments	6,673
Less: Amounts representing interest	(1,709)
Present value of lease payments	4,964
Operating lease liability, noncurrent	4,964	$ 129
Total operating lease liability	$ 4,964

Commitments and Contingencies - Operating Lease Supplemental Cash Flow Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 192

Commitments and Contingencies - Operating Lease Additional Information (Details)	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Weighted-average remaining lease term (in years)	7 years 7 months 6 days
Weighted-average discount rate	7.00%

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Components of Convertible Preferred Stock (Details) - USD ($)	Dec. 31, 2020	Feb. 05, 2020	Feb. 04, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized (in shares)	0		10,000,000	48,787,898
Convertible preferred stock, shares issued (in shares)	0			24,385,388
Convertible preferred stock, shares outstanding (in shares)	0	0		24,385,388	16,262,425	3,740,791
Net Carrying Value	$ 0			$ 166,491,000	$ 72,252,000	$ 7,154,000
Liquidation Preference				$ 166,300,000
Series A
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized (in shares)				13,800,000
Convertible preferred stock, shares issued (in shares)				6,897,575
Convertible preferred stock, shares outstanding (in shares)				6,897,575
Net Carrying Value				$ 14,340,000
Liquidation Preference				$ 13,800,000
Series B
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized (in shares)				18,736,270
Convertible preferred stock, shares issued (in shares)				9,364,850
Convertible preferred stock, shares outstanding (in shares)				9,364,850
Net Carrying Value				$ 57,912,000
Liquidation Preference				$ 58,000,000
Series C
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized (in shares)				16,251,628
Convertible preferred stock, shares issued (in shares)				8,122,963
Convertible preferred stock, shares outstanding (in shares)				8,122,963
Net Carrying Value				$ 94,239,000
Liquidation Preference				$ 94,500,000

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Details)	1 Months Ended					12 Months Ended
	Feb. 29, 2020 shares	Oct. 31, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Mar. 31, 2018 $ / shares shares	Apr. 30, 2017 $ / shares shares	Dec. 31, 2020 USD ($) vote $ / shares shares	Dec. 31, 2019 $ / shares shares	Dec. 31, 2018 shares	Mar. 31, 2018 USD ($) $ / shares	Feb. 04, 2020 $ / shares shares
Class of Stock [Line Items]
Votes per share of common stock \| vote						1
Dividends declared \| $						$ 0
Common stock, shares authorized (in shares)						300,000,000	65,820,000			300,000,000
Common stock, par value (in USD per share) \| $ / shares						$ 0.0001	$ 0.0001			$ 0.0001
Convertible preferred stock, shares authorized (in shares)						0	48,787,898			10,000,000
Convertible preferred stock, par value (In USD per share) \| $ / shares						$ 0.0001	$ 0.0001			$ 0.0001
Preferred stock, shares outstanding (in shares)						0	0
Common Stock
Class of Stock [Line Items]
Conversion of preferred stock into common stock upon initial public offering (in shares)	24,385,388					24,385,388
Series C
Class of Stock [Line Items]
Preferred stock issued (in shares)		8,122,963					8,122,963
Purchase price per share (in USD per share) \| $ / shares		$ 11.63
Proceeds from issuance of convertible preferred stock \| $		$ 94,200,000
Convertible preferred stock, shares authorized (in shares)							16,251,628
Series B
Class of Stock [Line Items]
Preferred stock issued (in shares)			9,364,850					8,880,462
Purchase price per share (in USD per share) \| $ / shares			$ 6.19
Proceeds from issuance of convertible preferred stock \| $			$ 54,900,000
Convertible preferred stock, shares authorized (in shares)							18,736,270
Series A
Class of Stock [Line Items]
Preferred stock issued (in shares)				3,156,784	3,590,845			3,156,784
Purchase price per share (in USD per share) \| $ / shares				$ 2.00	$ 2.00				$ 2.00
Proceeds from issuance of convertible preferred stock \| $									$ 13,400,000
Number of shares issued in transaction (in shares)					149,946
Convertible preferred stock, shares authorized (in shares)							13,800,000

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Shares of Common Stock for Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved (in shares)	6,320,204	28,452,008
Options issued and outstanding
Class of Stock [Line Items]
Common stock reserved (in shares)	3,655,945	2,516,470
Common stock awards available for grant under employee benefit plans
Class of Stock [Line Items]
Common stock reserved (in shares)	2,501,329	1,550,150
Restricted stock units outstanding
Class of Stock [Line Items]
Common stock reserved (in shares)	162,930	0
Convertible preferred stock outstanding
Class of Stock [Line Items]
Common stock reserved (in shares)	0	24,385,388

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		4 Months Ended	6 Months Ended	12 Months Ended
	Jan. 01, 2021	Jan. 30, 2020	Jul. 31, 2018	Aug. 31, 2016	May 31, 2020	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)							6,320,204	28,452,008
Intrinsic value of options exercised during the period							$ 3,600
Grant date fair value of options vested during the period							$ 2,800
Grant date fair value of options vested during the period (in USD per share)							$ 18.16
Early exercise liability, current							$ 176	$ 225
Stock-based compensation expense							$ 7,943	$ 824	$ 151
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued pursuant to the employee stock purchase plan (in shares)					19,862	14,326	34,188
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost							$ 23,200
Recognition period for unrecognized compensation costs related to unvested options expected to vest							3 years 2 months 12 days
Expected dividend yield							0.00%	0.00%	0.00%
RSU's subject to future vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)							162,930	0
Vesting period of stock-based awards granted							4 years
Granted (in shares)							163,560	0
Unrecognized compensation cost							$ 3,600
Recognition period for unrecognized compensation costs related to unvested options expected to vest							3 years 7 months 6 days
Restricted common stock vested (in shares)							0
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of restricted stock issued to founders (in shares)				1,187,738
Restricted stock \| First anniversary date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage				25.00%
Service Condition Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of restricted stock issued to founders (in shares)				1,102,903
Service Condition Restricted Stock \| First anniversary date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of restricted stock issued to founders (in shares)				1,102,903
Service Condition Restricted Stock \| Monthly basis
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vesting on a monthly basis (in shares)				827,177
Performance Condition Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of restricted stock issued to founders (in shares)				84,835
Restricted common stock vested (in shares)			84,835				137,863	1,049,875
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares available for grant, percentage of shares outstanding		1.00%
Purchase price of common stock, as a percentage of closing trading price per share		85.00%
Stock-based compensation expense							$ 346
Employee Stock Purchase Plan \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for sale under the ESPP (in shares)		351,000
Maximum shares to be issued		5,265,000
Employee Stock Purchase Plan \| Common Stock \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (in shares)	436,778
2020 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)		2,134,000
Increase in shares available for grant, percentage of shares outstanding		4.00%
Based number of options issuable (in shares)		11,000,000
Shares available for grant							2,184,517
Expected dividend yield							0.00%
2020 Equity Incentive Plan \| Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (in shares)	1,747,112
2020 Equity Incentive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock-based awards granted							4 years
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)		1,550,150
Early exercise liability							$ 258	$ 409
Early exercise liability, current							176	225
Early exercise liability, noncurrent							$ 82	$ 184

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of Options
Beginning balance, number of options (in shares)	2,516,470	391,098	472,991
Granted (in shares)	1,368,825	2,421,221	836,992
Exercised (in shares)	(197,228)	(250,865)	(918,885)
Forfeited (in shares)	(32,122)	(31,863)
Expired (in shares)		(13,121)
Ending balance, number of options (in shares)	3,655,945	2,516,470	391,098	472,991
Weighted- Average Exercise Price
Beginning balance, weighted-average exercise price (in USD per share)	$ 3.47	$ 0.82	$ 0.36
Granted (in USD per share)	26.83	3.59	0.64
Exercised (in USD per share)	2.67	1.02	0.42
Forfeited (in USD per share)	22.82	0.58
Expired (in USD per share)		0.58
Ending balance, weighted-average exercise price (in USD per share)	$ 12.09	$ 3.47	$ 0.82	$ 0.36
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercisable (in shares)	2,034,061
Exercisable, Weighted-Average Exercise Price (in USD per share)	$ 7.33
Remaining Contractual Term (Years)	8 years 9 months 10 days	9 years 5 months 8 days	9 years 6 months 21 days	9 years 4 months 24 days
Remaining contractual term, exercisable (years)	8 years 6 months 14 days
Aggregate Intrinsic Value	$ 59,274	$ 7,673	$ 334	$ 360
Intrinsic value, exercisable	$ 42,314

Stock-Based Compensation - Restricted Stock Unit Activity (Details) - Restricted stock units outstanding - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Units
Beginning balance (in shares)	0
Granted (in shares)	163,560	0
Vested (in shares)	0
Forfeited (in shares)	(630)
Ending balance (in shares)	162,930	0
Weighted-Average Grant Date Fair Value
Beginning balance (in USD per share)	$ 0
Granted (in USD per share)	27.26
Vested (in USD per share)	0
Forfeited (in USD per share)	27.61
Ending balance (in USD per share)	$ 27.26	$ 0

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 7,943	$ 824	$ 151
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	3,503	351	44
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 4,440	$ 473	$ 107

Stock-Based Compensation - Assumptions in Calculating Stock Option Awards (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	78.40%	68.60%	68.20%
Expected volatility, maximum	80.80%	72.50%	72.40%
Risk-free interest rate, minimum	0.30%	1.60%	2.70%
Risk-free interest rate, maximum	1.40%	2.60%	2.90%
Dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 1 month 6 days	5 years 10 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 9 months 18 days	6 years 7 months 6 days	6 years 1 month 6 days

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Provision for income tax	$ 0	$ 0	$ 0
Increase in valuation allowance	30,700,000	9,600,000
Operating loss carryforwards, subject to expiration	3,500,000
Operating loss carryforwards, not subject to expiration	177,200,000
Liability related to uncertain tax positions	0	0
Unrecognized tax benefits	20,274,000	6,448,000	2,241,000	$ 441,000
Unrecognized tax benefits that would Impact effective tax rate	16,700,000
Unrecognized tax benefits, income tax penalties and interest expense	0	$ 0	$ 0
Federal
Income Tax Contingency [Line Items]
Operating loss carryforwards	180,700,000
Federal \| Research tax credit carryforward
Income Tax Contingency [Line Items]
Tax credit carryforwards	6,400,000
State
Income Tax Contingency [Line Items]
Operating loss carryforwards	3,200,000
State \| CALIFORNIA
Income Tax Contingency [Line Items]
Operating loss carryforwards	180,800,000
State \| Research tax credit carryforward
Income Tax Contingency [Line Items]
Tax credit carryforwards	$ 1,400,000

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax provision at U.S. statutory rate	$ (28,493,000)	$ (8,819,000)	$ (4,043,000)
State income taxes, net of federal benefit	(9,213,000)	(2,786,000)	(1,224,000)
Research and development tax and other credits	(2,413,000)	(655,000)	(265,000)
Change in valuation allowance	30,708,000	9,598,000	4,418,000
Uncertain tax positions	8,801,000	2,604,000	911,000
Permanent differences	616,000	58,000	219,000
Fair value adjustment	0	0	(16,000)
Other	(6,000)	0	0
Provision for income tax	$ 0	$ 0	$ 0

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 38,196	$ 11,457
Intangibles	1,777	1,937
Research and development tax credits	3,370	1,092
Accruals and reserves	1,041	355
Right-of-use liability	1,274	79
Stock-based compensation	1,122	62
Property and equipment	0	2
Gross deferred tax assets	46,780	14,984
Deferred tax liabilities:
Property and equipment	(299)	0
Right-of-use asset	(859)	(68)
Gross deferred tax liabilities	(1,158)	(68)
Deferred tax assets, net:
Net deferred tax assets	45,622	14,916
Less valuation allowance	(45,622)	(14,916)
Total deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Unrecognized Tax Benefits Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 6,448	$ 2,241	$ 441
Increases related to tax positions taken during a prior year	5	4	0
Increases related to tax positions taken during the current year	13,821	4,203	1,800
Ending balance	$ 20,274	$ 6,448	$ 2,241

Net Loss Per Share (Details) - shares	12 Months Ended
Net Loss Per Share (Details) - shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	4,161,993	27,660,774	17,711,278
Convertible preferred stock on an as-converted basis
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	0	24,385,388	16,262,425
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	3,655,945	2,516,470	391,098
Early exercised options subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	339,385	621,053	644,166
RSU's subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	162,930	0	0
ESPP shares subject to future issuance
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	3,733	0	0
Restricted stock subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive shares excluded from the calculation of net loss per share (in shares)	0	137,863	413,589

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total operating expenses	$ 34,064	$ 38,303	$ 35,627	$ 28,651	$ 12,994	$ 14,648	$ 8,538	$ 6,952	$ 136,645	$ 43,132	$ 19,735
Other income, net	15	99	215	638	426	168	248	294	967	1,136	480
Net loss	$ (34,049)	$ (38,204)	$ (35,412)	$ (28,013)	$ (12,568)	$ (14,480)	$ (8,290)	$ (6,658)	$ (135,678)	$ (41,996)	$ (19,255)
Net loss per share, basic and diluted (in USD per share)	$ (0.79)	$ (1.01)	$ (0.94)	$ (1.15)	$ (6.13)	$ (7.56)	$ (4.69)	$ (4.08)	$ (3.80)	$ (22.78)	$ (15.53)

- Definition

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

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+ Details

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Feb. 05, 2021	Feb. 04, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 06, 2020
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs			$ 128,360	$ 0	$ 0
Third equity offering \| Subsequent Event
Subsequent Event [Line Items]
Proceeds from issuance of common stock, net of issuance costs	$ 207,400
Common Stock
Subsequent Event [Line Items]
Stock price (in USD per share)						$ 25.00
Common Stock \| Subsequent Event
Subsequent Event [Line Items]
Stock price (in USD per share)	$ 35.00
Common Stock \| Third equity offering \| Subsequent Event
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares)	6,325,000
Common Stock \| Underwriters' option
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares)		1,406,250
Common Stock \| Underwriters' option \| Subsequent Event
Subsequent Event [Line Items]
Number of shares issued in transaction (in shares)	825,000