0001564590-21-009867 | 10-K | XBRL Viewer

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2020	Feb. 24, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	CRTX
Entity Registrant Name	Cortexyme, Inc.
Entity Central Index Key	0001662774
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		29,552,123
Entity Public Float			$ 1,370
Entity File Number	001-38890
Entity Tax Identification Number	90-1024039
Entity Address, Address Line One	269 East Grand Ave.
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	415
Local Phone Number	910-5717
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, par value $0.001 per share
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Part III incorporates by reference certain information from the registrant’s definitive proxy statement (the “Proxy Statement”) relating to its 2021 Annual Meeting of Stockholders. The Proxy Statement will be filed with the United States Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.

Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 66,841,000	$ 51,214,000
Short term investments	66,979,000	48,650,000
Prepaid expenses and other current assets	4,042,000	6,192,000
Total current assets	137,862,000	106,056,000
Property and equipment, net	427,000	709,000
Operating lease right-of-use assets, net	674,000	625,000
Long term investments	50,464,000	16,763,000
Other assets	39,000	217,000
Total assets	189,466,000	124,370,000
Current liabilities:
Accounts payable	3,555,000	3,075,000
Accrued expenses and other current liabilities	13,441,000	5,817,000
Total current liabilities	16,996,000	8,892,000
Long-term operating lease liability	208,000
Total liabilities	17,204,000	8,892,000
Commitments and contingencies (See Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 authorized, no shares issued and outstanding as of December 31, 2020 and 2019, respectively
Common stock, $0.001 par value, 100,000,000 shares authorized, 29,543,222 and 26,869,413 issued and outstanding as of December 31, 2020 and 2019, respectively	29,000	27,000
Additional paid in capital	318,574,000	185,196,000
Accumulated other comprehensive income	313,000	60,000
Accumulated deficit	(146,654,000)	(69,805,000)
Total stockholders’ equity	172,262,000	115,478,000
Total liabilities and stockholders’ equity	$ 189,466,000	$ 124,370,000

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	29,543,222	26,869,413
Common stock, shares outstanding	29,543,222	26,869,413

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	$ 61,307	$ 30,214	$ 10,085
General and administrative	17,586	8,954	2,034
Total operating expenses	78,893	39,168	12,119
Loss from operations	(78,893)	(39,168)	(12,119)
Interest income	2,044	2,188	806
Interest expense			(957)
Change in fair value of derivative liability			(206)
Net loss	(76,849)	(36,980)	(12,476)
Other comprehensive income / (loss):
Unrealized gain / (loss) on available for sales securities	253	109	(49)
Total comprehensive loss	$ (76,596)	$ (36,871)	$ (12,525)
Net loss per share - basic and diluted	$ (2.63)	$ (1.94)	$ (3.71)
Weighted average shares of common stock outstanding - basic and diluted	29,176,232	19,031,940	3,362,192

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Private Placement	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Common Stock	Common Stock Private Placement	Additional Paid in Capital	Additional Paid in Capital Private Placement	Other Comprehensive Income / (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ (20,280)				$ 3		$ 66			$ (20,349)
Beginning balance, shares at Dec. 31, 2017			9,008,919
Beginning balance at Dec. 31, 2017			$ 17,178
Beginning balance, shares at Dec. 31, 2017					3,361,016
Issuance of Series B redeemable convertible preferred stock, net of issuance costs of $157				$ 75,688
Issuance of Series B redeemable convertible preferred stock, net of issuance costs, shares				7,890,466
Issuance of Series B redeemable convertible preferred stock in connection with the conversion of convertible promissory notes and accrued interest				$ 11,027
Issuance of Series B redeemable convertible preferred stock in connection with the conversion of convertible promissory notes and accrued interest, shares				1,147,205
Issuance of Series B redeemable convertible preferred stock in connection with the facility lease agreement, shares				114,437
Vesting of Series B redeemable convertible preferred stock in lieu of rent				$ 153
Exercise of stock options	24						24
Exercise of stock options, shares					51,350
Stock based compensation	155						155
Other Comprehensive Income (Loss)	(49)								$ (49)
Net loss	(12,476)									(12,476)
Ending balance at Dec. 31, 2018	(32,626)				$ 3		245		(49)	(32,825)
Ending balance, shares at Dec. 31, 2018			9,008,919	9,152,108
Ending balance at Dec. 31, 2018			$ 17,178	$ 86,868
Ending balance, shares at Dec. 31, 2018					3,412,366
Conversion of redeemable convertiblepreferred stock to common stock	104,994				$ 18		104,976
Conversion of redeemable convertible preferred stock to common stock, shares			(9,008,919)	(9,152,108)
Conversion of redeemable convertible preferred stock to common stock			$ (17,178)	$ (87,816)
Conversion of redeemable convertible preferred stock to common stock, shares					18,161,027
Vesting of Series B redeemable convertible preferred stock in lieu of rent				$ 948
Initial public offering of common stock, net of issuance costs	77,827				$ 5		77,822
Initial public offering of common stock, net of issuance costs, shares					5,073,800
Exercise of stock options	97				$ 1		96
Exercise of stock options, shares					194,279
Stock based compensation	2,056						2,056
Exercise of stock warrant	1						1
Exercise of stock warrant, shares					27,941
Other Comprehensive Income (Loss)	109								109
Net loss	(36,980)									(36,980)
Ending balance at Dec. 31, 2019	115,478				$ 27		185,196		60	(69,805)
Ending balance, shares at Dec. 31, 2019					26,869,413
Initial public offering of common stock, net of issuance costs		$ 117,628				$ 2		$ 117,626
Initial public offering of common stock, net of issuance costs, shares						2,500,000
Exercise of stock options	1,282						1,282
Exercise of stock options, shares					173,809
Stock based compensation	14,470						14,470
Other Comprehensive Income (Loss)	253								253
Net loss	(76,849)									(76,849)
Ending balance at Dec. 31, 2020	$ 172,262				$ 29		$ 318,574		$ 313	$ (146,654)
Ending balance, shares at Dec. 31, 2020					29,543,222

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Series B Redeemable Convertible Preferred Stock
Stock issuance costs			$ 157
Common Stock
Stock issuance costs		$ 8,427
Common Stock \| Private Placement
Stock issuance costs	$ 7,372

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	$ (76,849,000)	$ (36,980,000)	$ (12,476,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash interest expense related to convertible promissory notes			263,000
Non-cash rent expense	367,000	367,000	153,000
Stock based compensation	14,470,000	2,056,000	155,000
Depreciation and amortization	332,000	188,000	51,000
Accretion of discount on convertible promissory notes payable			694,000
Amortization of premium / (discount) on available for sale investments	635,000	(812,000)	(351,000)
Change in fair value of derivative liability			206,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,184,000	(5,324,000)	(690,000)
Other assets	178,000	(207,000)	50,000
Accounts payable	480,000	2,580,000	(23,000)
Accrued expenses and other current liabilities	7,385,000	4,855,000	273,000
Net cash used in operating activities	(50,818,000)	(33,277,000)	(11,695,000)
Cash flow from investing activities:
Purchase of investments	(187,141,000)	(135,415,000)	(55,242,000)
Proceeds from maturities of investments	134,762,000	117,723,000	8,700,000
Purchase of property and equipment	(52,000)	(55,000)	(212,000)
Net cash used in investing activities	(52,431,000)	(17,747,000)	(46,754,000)
Cash flows from financing activities:
Payments of finance leases	(34,000)	(559,000)
Proceeds from issuance of convertible promissory note payable			250,000
Proceeds from issuance of commons stock upon exercise of stock options	1,282,000	97,000	24,000
Proceeds from Series B redeemable convertible preferred stock, net of issuance costs			75,688,000
Proceeds from stock warrant exercise		1,000
Deferred initial public offering costs			(34,000)
Proceeds from initial public offering, net of stock offering costs		77,827,000
Proceeds from private placement offering, net of issuance costs	117,628,000
Net cash provided by financing activities	118,876,000	77,366,000	75,928,000
Net increase in cash and cash equivalents	15,627,000	26,342,000	17,479,000
Cash and cash equivalents at beginning of period	51,214,000	24,872,000	7,393,000
Cash and cash equivalents at end of period	66,841,000	51,214,000	24,872,000
Supplemental disclosures of non-cash information:
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 620,000	878,000
Series A Redeemable Convertible Preferred Stock
Supplemental disclosures of non-cash information:
Conversion of redeemable convertible preferred stock to common stock on initial public offering		17,178,000
Series B Redeemable Convertible Preferred Stock
Supplemental disclosures of non-cash information:
Conversion of redeemable convertible preferred stock to common stock on initial public offering		87,816,000
Acceleration of vesting of stock on initial public offering		$ 856,000
Issuance of stock in connection with conversion of convertible promissory notes and accrued interest			11,027,000
Issuance of stock for facility lease			$ 1,100,000

Organization

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization

Note 1. Organization

Description of Business

Cortexyme, Inc. (the “Company”) was incorporated in the State of Delaware in June 2012 and is headquartered in South San Francisco, California. The Company is a clinical stage biopharmaceutical company focused on developing therapeutics based on data supporting a new theory of the cause of Alzheimer’s disease and other degenerative disorders. Cortexyme is targeting a specific, infectious pathogen tied to neurodegeneration and chronic inflammation in humans and animal models.

Initial Public Offering

On May 8, 2019, the Company’s registration statement on Form S-1 (File No. 333-230853) for its initial public offering of common stock (“IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). On May 13, 2019, the Company closed its IPO with the sale of 5,073,800 shares of common stock, which included 661,800 shares of common stock issued upon the exercise in full of the underwriters’ option to purchase additional shares, at a public offering price of $17.00 per share, resulting in net proceeds of $77.8 million, after deducting underwriting discounts and commissions and estimated offering expenses paid by the Company.

In addition, in connection with the closing of the IPO, all of the Company’s outstanding shares of redeemable convertible preferred stock were automatically converted into 18,161,027 shares of common stock, and there are no shares of redeemable convertible preferred stock outstanding as of December 31, 2020.

Private Investment in Public Equity (“PIPE”)

In February 2020, the Company completed a private investment in public equity transaction (“PIPE Financing”). The Company entered into Stock Purchase Agreements (the “Purchase Agreements”) with certain accredited investors, including an entity affiliated with a member of the Company’s Board of Directors, pursuant to which the Company sold and issued shares of common stock for aggregate gross proceeds of $125.0 million. Costs related to the offering were $7.4 million. Pursuant to the Purchase Agreements, the Company sold 2,500,000 common shares at $50.00 per common share. In connection with the PIPE Financing, the Company filed a registration statement on Form S-1 (File No. 333-237594), with the SEC registering for resale the shares of common stock issued in the PIPE Financing. The registration statement was declared effective by the SEC on April 13, 2020.

Liquidity and Capital Resources

The Company has incurred losses and negative cash flows from operations since inception and expects to continue to generate operating losses for the foreseeable future. As of December 31, 2020, the Company had an accumulated deficit of $146.7 million. Since inception through December 31, 2020, the Company has funded operations primarily with the net proceeds from the issuance of convertible promissory notes, from the issuance of redeemable convertible preferred stock, from the net proceeds from the IPO and from the net proceeds from the PIPE Financing. As of December 31, 2020, the Company had cash, cash equivalents, and short-term investments of $133.8 million, which it believes will be sufficient to fund its planned operations for a period of at least 12 months from the date of the issuance of the accompanying financial statements. The Company also has long-term investments of $50.5 million.

Management expects to incur additional losses in the future to fund its operations and conduct product research and development and may need to raise additional capital to fully implement its business plan. The Company may raise additional capital through the issuance of equity securities, debt financings or other sources in order to further implement its business plan. However, if such financing is not available when needed and at adequate levels, the Company will need to reevaluate its operating plan and may be required to delay the development of its product candidate.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements and the notes thereto have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) pursuant to the instructions of the SEC on Form 10-K through the rules and interpretive releases of the SEC under federal securities law.

Use of Estimates

The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and expenses, as well as related disclosure of contingent assets and liabilities. The most significant estimates used in the Company’s financial statements relate to the determination of the fair value of common stock prior to the initial public offering, accruals for research and development costs, useful lives of long-lived assets, stock-based compensation and related assumptions, the incremental borrowing rate for leases and income tax uncertainties, including a valuation allowance for deferred tax assets; and contingencies. The Company bases its estimates on historical experience and on various other market specific and other relevant assumptions that it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from the Company’s estimates.

Risk and Uncertainties

The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential drug candidates, uncertainty of market acceptance of the Company’s drug candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals and sole source suppliers. The Company’s drug candidate will require approvals from the U.S. Food and Drug Administration (FDA) and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any drug candidate will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any drug candidate, it could have a materially adverse impact on the Company.

In connection with the COVID-19 pandemic, governments have implemented significant measures, including closures, quarantines, travel restrictions and other social distancing directives, intended to control the spread of the virus. Companies have also taken precautions, such as requiring employees to work remotely, imposing travel restrictions, and temporarily closing businesses. To the extent that these restrictions remain in place, additional prevention and mitigation measures are implemented in the future or there is uncertainty about the effectiveness of these or any other measures to contain or treat COVID-19, there is likely to be a continuing, adverse impact on global economic conditions and consumer confidence and spending, which could materially and adversely affect the Company’s research and development, as well as operational activities. At this time, the Company continues to manage and mitigate potential disruptions to its research and future manufacturing and supply chain considerations. The Company has not experienced significant hinderances to its operations or material negative financial impacts as compared to prior periods. At this time, the extent to which the COVID-19 pandemic impacts the Company’s business will depend on future developments which are highly uncertain and cannot be predicted.

Segments

The Company operates and manages its business as one reportable and operating segment, which is the business of developing and commercializing therapeutics. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating and evaluating financial performance. All long-lived assets are maintained in the United States of America.

Cash, Cash Equivalents and Investments

The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash equivalents include marketable securities. Management determines the appropriate classification of its investments in debt securities at the time of purchase and at the end of each reporting period. Investments with original maturities beyond three months at the date of purchase and which mature at, or less than twelve months from the balance sheet date are classified as short-term investments. Investments with a maturity beyond twelve months from the balance sheet date are classified as long-term investments. Collectively, cash equivalents, short-term investments and long-term investments are considered available-for-sale and are recorded at fair value. Unrealized gains and losses are recorded as a component of other comprehensive loss in the statement of operations and included as a separate component of redeemable convertible preferred stock and stockholders’ equity (deficit). Realized gains and losses are included in interest income in the statements of operations and comprehensive loss.

Premiums (discounts) are amortized (accreted) over the life of the related investment as an adjustment to yield using the straight-line interest method. Dividend and interest income are recognized when earned. These amounts are recorded in “interest income” in the statements of operations and comprehensive loss.

Property and Equipment, Net

Property and equipment are stated at cost and reduced by accumulated depreciation. Depreciation expense is recognized using the straight-line method over the estimated useful lives of the respective assets. Depreciation and amortization begin at the time the asset is placed in service. Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.

The useful lives of property and equipment are as follows:

Computer equipment	3 years
Lab equipment	5 years
Finance lease right of use assets	Shorter of estimated useful life or lease term
Leasehold improvement	Shorter of estimated useful life or lease term
Office furniture	3 years

Concentration of Credit Risk

Cash equivalents, short-term and long-term investments are financial instruments that potentially subject the Company to concentrations of credit risk. The Company invests in money market funds, repurchase agreements, treasury bills and notes, government bonds, commercial paper and corporate notes. The Company limits its credit risk associated with cash equivalents, short-term and long-term investments by placing them with banks and institutions it believes are highly credit worthy and in highly rated investments.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment charge would be recorded when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is assessed using discounted cash flows or other appropriate measures of fair value. The Company did not recognize any impairment charges for the years ended December 31, 2020, 2019 and 2018.

Leases

The Company adopted Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842) as of January 1, 2019 using the modified retrospective method. The results for years ended December 31, 2019 and 2020 are presented under ASC 842. The results for the year ended December 31, 2018 were not adjusted and continue to be reported in accordance with historical accounting under prior lease guidance, ASC 840, Leases (Topic 840). The Company also elected the package of practical expedients under the transition guidance that will retain the historical lease classification and initial direct costs for any leases that existed prior to adoption of the new guidance and the practical expedient to not separate lease and non-lease components.

The Company determines if an arrangement includes a lease at inception. Right-of-use lease assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. The right-of-use lease asset includes any lease payments made and excludes lease incentives. Incremental borrowing rate is used in determining the present value of future payments. The Company applies a portfolio approach to the property leases to apply an incremental borrowing rate to leases with similar lease terms. The lease terms may include options to extend or terminate the lease. The Company recognizes the options to extend the lease as part of the right-of-use lease assets and lease liabilities only if it is reasonably certain that the option would be exercised. Lease expense for minimum lease payments is recognized on a straight-line basis over the non-cancelable lease term.

As a result of the adoption of the new guidance, effective January 1, 2019, the Company recorded a right-of-use lease asset of $0.9 million, a short-term lease liability of $0.3 million, and a long-term lease liability of $0.6 million and no cumulative effect adjustment was made to the retained earnings as of the adoption date. See “Note 6. Leases” for further disclosure.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development expenses consist primarily of personnel costs for the Company’s research and product development employees. Also included are non-personnel costs such as professional fees payable to third parties for preclinical and clinical studies and research services, laboratory supplies and equipment maintenance, product licenses, and other consulting costs. The Company estimates preclinical and clinical study and research expenses based on the services performed, pursuant to contracts with contract research organizations (“CROs”) that conduct and manage preclinical and clinical studies and research services on its behalf. Expenses related to clinical studies are based on estimates of the services received and efforts expended pursuant to contracts with many research institutions, clinical research organizations and other service providers that conduct and manage clinical studies on our behalf. The financial terms of these agreements are subject to negotiation and vary from contract to contract and may result in uneven payment flows. Generally, these agreements set forth the scope of work to be performed at a fixed fee or unit price. Payments under the contracts are mainly driven by time and materials incurred by these service providers. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered. Expenses related to clinical studies are generally recorded based on the timing of when services that have been performed on the Company’s behalf by the service providers, clinical trial budgets and in accordance with the contracts and related amendments. The determination of timing involves reviewing open contracts and purchase orders, communicating with applicable personnel to identify the timing of when services that have been performed on the Company’s behalf and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of actual cost. The Company periodically confirms the accuracy of estimates with the service providers and makes adjustments if necessary. Examples of estimated clinical expenses include:

•

fees paid to Contract Research Organizations, or CROs, in connection with clinical studies;

•

fees paid to investigative sites in connection with clinical studies;

•

fees paid to contract manufacturers in connection with the production of clinical study materials; and

•

fees paid to vendors in connection with preclinical development activities.

If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the prepaid or accrual accordingly. Payments associated with licensing agreements to acquire exclusive licenses to develop, use, manufacture and commercialize products that have not reached technological feasibility and do not have alternate commercial use are expensed as incurred.

Patent Costs

The Company has no historical data to support a probable future economic benefit for the arising patent applications, filing and prosecution costs. Therefore, patent costs are expensed as incurred.

Stock-Based Compensation

The Company accounts for stock-based compensation arrangements with employees in accordance with Accounting Standards Codification (“ASC”) 718, Compensation—Stock Compensation. Stock-based awards granted include stock options with service-based vesting. ASC 718 requires the recognition of compensation expense, using a fair value-based method, for costs related to all stock-based payments. The Company’s determination of the fair value of stock options with service-based vesting on the date of grant utilizes the Black-Scholes option-pricing model and is impacted by its common stock price as well as other variables including: but not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. The fair value of a stock-based award is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. Stock-based compensation expense is recognized based on the fair value determined on the date of grant and is reduced for forfeitures as they occur. The Company uses a Monte Carlo Simulation method to estimate the grant date fair value of stock option awards with market-based performance conditions.

Redeemable Convertible Preferred Stock

The Company recorded all shares of convertible preferred stock at their respective fair values less issuance costs on the dates of issuance. The convertible preferred stock was recorded outside of stockholders’ equity (deficit) because, in the event of certain deemed liquidation events considered not solely within the Company’s control, such as a merger, acquisition and sale of all or substantially all of all the Company’s assets, the convertible preferred stock will become redeemable at the option of the holders. Additionally, holders with 60% of majority had the right to demand redemption on or after May 23, 2025. In the event of a change of control of the Company, proceeds received from the sale of such shares would have been distributed in accordance with the liquidation preferences set forth in the Company’s Amended and Restated Certificate of Incorporation unless the holders of convertible preferred stock had converted their shares of convertible preferred stock into shares of common stock. The Company determined not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. In connection with the closing of the IPO, all of the Company’s outstanding shares of redeemable convertible preferred stock were automatically converted into 18,161,027 shares of common stock, and there are no shares of redeemable convertible preferred stock outstanding as of December 31, 2020 and 2019.

Income Taxes

The Company accounts for income taxes under the asset and liability method. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating loss and credit carryforwards and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized.

The Company accounts for uncertain tax positions in accordance with ASC 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

The Company includes any penalties and interest expense related to income taxes as a component of other expense and interest expense, net, as necessary.

Comprehensive Income (Loss)

The Company is required to report all components of comprehensive income (loss), including net loss, in the financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as a change in equity of a business enterprise during a period, resulting from transactions and other events and circumstances from non-owner sources. The Company had unrealized gain from its available-for-sale securities during the years ended December 31, 2020 and 2019 and an unrealized loss from its available-for sale securities during the year ended December 31, 2018, which are considered other comprehensive income (loss).

Net Loss per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and common share equivalents of potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, warrants and common stock options are considered to be potentially dilutive securities. Because the Company reported a net loss for the years ended December 31, 2020, 2019 and 2018, and the inclusion of the potentially dilutive securities would be antidilutive, diluted net loss per share is the same as basic net loss per share for both periods.

Recent Accounting Pronouncements Adopted

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. The new guidance changes disclosure requirements related to fair value measurements as part of the disclosure framework project. The disclosure framework project aims to improve the effectiveness of disclosures in the notes to the financial statements by focusing on requirements that clearly communicate the most important information to users of the financial statements. The Company adopted this effective January 1, 2020. The adoption of this pronouncement did not have a material impact on its financial statements or disclosures.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40)”: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”), which clarifies the accounting for implementation costs in cloud computing arrangements. The Company adopted the standard prospectively on January 1, 2020. The adoption of this pronouncement did not have a material impact on its financial statements.

Recent Accounting Pronouncements Not Yet Adopted

The following are new accounting pronouncements that the Company is evaluating for future impacts on its financial statements:

Financial Instruments—Credit Losses: In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments which amends the principles around the recognition of credit losses by mandating entities incorporate an estimate of current expected credit losses when determining the value of certain assets. The guidance also amends reporting around allowances for credit losses on available-for-sale marketable securities. In November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815) and Leases (Topic 842): Effective Dates, which established that a one-time determination of the effective date for ASU 2016-13 would be based on the Company’s SEC reporting status as of November 15, 2019. The Company was a Smaller Reporting Company as defined by the SEC, and therefore, ASU 2016-13 is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The Company is evaluating the impact of the guidance on its financial statements.

All other newly issued accounting pronouncements not yet effective have been deemed either immaterial or not applicable.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 3. Fair Value Measurements

The fair value of our financial instruments reflects the amounts that we estimate we would receive in connection with the sale of an asset or pay in connection with the transfer of a liability in an orderly transaction between market participants at the measurement date (exit price). We disclose and recognize the fair value of our assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that are significant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy as follows:

Level 1 - Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date;

Level 2 - Inputs other than quoted prices that are observable for the assets or liability either directly or indirectly, including inputs in markets that are not considered to be active;

Level 3 - Inputs that are unobservable. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.

The carrying amounts of the Company’s financial instruments, which include cash, accounts payable and accrued liabilities and other current liabilities approximate their fair values due to their short maturities.

Our assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. During the years presented, the Company has not changed the manner in which it values assets and liabilities that are measured at fair value using Level 3 inputs. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers within the hierarchy during the years ended December 31, 2020 and 2019.

Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of December 31, 2020 and 2019 are presented in the following tables (in thousands):

	Fair Value Measurements at December 31, 2020
	Total		Level 1		Level 2		Level 3
Money market funds	$	15,661	$	15,661	$	—	$	—
Certificates of Deposit		30,765		—		30,765		—
Repurchase Agreements		15,000		—		15,000
Corporate notes		75,426		—		75,426		—
Government and agency notes		8,296		—		8,296		—
Municipal notes		3,446		—		3,446		—
Total	$	148,594	$	15,661	$	132,933	$	—

	Fair Value Measurements at December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	30,054	$	30,054	$	—	$	—
Certificates of Deposit		20,046		—		20,046		—
Repurchase Agreements		15,000		—		15,000		—
Corporate notes		38,783		—		38,783		—
Government notes		7,574		—		7,574		—
Commercial Paper		1,096		—		1,096		—
Total	$	112,553	$	30,054	$	82,499	$	—

- 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

Cash, Cash Equivalents and Investments

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Cash, Cash Equivalents and Investments

Note 4: Cash, Cash Equivalents and Investments

The following tables categorize the fair values of cash, cash equivalents, short-term investments and long-term investments measured at fair value on a recurring basis on our balance sheets (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents:
Cash	$	35,690	$	4,074
Money market funds		15,661		30,054
Repurchase agreements		15,000		15,000
Certificates of deposit		490		985
Corporate notes		—		1,101
Total cash and cash equivalents	$	66,841	$	51,214

Short-term investments:
Commercial paper	$	—	$	1,096
Certificates of deposit		23,387		15,428
Municipal notes		2,365		—
Corporate notes		34,991		24,552
Government and agency notes		6,236		7,574
Total short-term investments	$	66,979	$	48,650

Long-term investments
Corporate notes	$	40,435	$	13,130
Certificates of deposit		6,888		3,633
Municipal notes		1,081		—
Government and agency notes		2,060		—
Total long-term investments	$	50,464	$	16,763

The investments are classified as available-for-sale securities. As of December 31, 2020, the weighted average remaining contractual maturities of available-for-sale securities was approximately 10 months. At December 31, 2020 and 2019, the balance in the Company’s accumulated other comprehensive income (loss) was comprised solely of activity related to the Company’s available-for-sale securities. There were no realized gains or losses recognized on the sale or maturity of available-for-sale securities for the years ended December 31, 2020, 2019 or 2018 and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the year. The Company has a limited number of available-for-sale securities in insignificant unrealized loss positions as of December 31, 2020 and 2019, which the Company does not intend to sell and has concluded it will not be required to sell before recovery of the amortized cost for the investment at maturity.

The following table summarizes the available-for-sale securities (in thousands):

	Fair Value Measurements at December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	15,661	$	—	$	—		$	15,661
Certificates of Deposit		30,603		162		—			30,765
Repurchase Agreements		15,000		—		—			15,000
Corporate notes		75,298		183		(55	)		75,426
Government and agency notes		8,274		22		—			8,296
Municipal notes		3,445		1		—			3,446
Total cash equivalents and investments	$	148,281	$	368	$	(55	)	$	148,594

Classified as:
Cash equivalents (maturities within 90 days)								$	31,151
Short-term investments (maturities within one year)									66,979
Long-term investments (maturities beyond 1 year)									50,464
Total cash equivalents and investments								$	148,594

	Fair Value Measurements at December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	30,054	$	—	$	—		$	30,054
Certificates of Deposit		19,992		54		—			20,046
Repurchase Agreements		15,000		—		—			15,000
Corporate notes		38,788		—		(5	)		38,783
Government notes		7,563		11					7,574
Commercial Paper		1,096		—		—			1,096
Total cash equivalents and investments	$	112,493	$	65	$	(5	)	$	112,553

Classified as:
Cash equivalents (maturities within 90 days)								$	47,140
Short-term investments (maturities within one year)									48,650
Long-term investments (maturities beyond 1 year)									16,763
Total cash equivalents and investments								$	112,553

Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Balance Sheet Components [Abstract]

Balance Sheet Components

Note 5: Balance Sheet Components

Prepaid Expenses and Other Current Assets

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

	December 31,
	2020		2019
Prepaid expenses	$	274	$	129
Prepaid insurance		964		858
Prepaid research and development expenses		2,110		4,517
Other current assets		694		688
Total prepaid expenses and other current assets	$	4,042	$	6,192

Property and equipment, net

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

	December 31,
	2020			2019
Computer equipment	$	33		$	28
Lab equipment		405			405
Finance lease right of use assets		557			559
Leasehold improvement		21			—
Office furniture		26			—
Less: accumulated amortization and depreciation		(615	)		(283	)
Property and equipment, net	$	427		$	709

Depreciation expense for property and equipment was $332,000, $188,000 and $51,000 for the years ended December 31, 2020, 2019, and 2018, respectively.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Personnel expenses	$	2,415	$	1,261
Professional fees		141		96
Research and development expenses		10,603		4,410
Other		282		50
Total accrued expenses and other current liabilities	$	13,441	$	5,817

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

Note 6. Leases

Real Estate Operating Leases

In June 2018, the Company entered into a three-year lease agreement with no renewal options with an investor in the Series B redeemable convertible preferred stock. The lease began on July 16, 2018 and provides 3,185 square feet of office and laboratory space in South San Francisco, California. The Company issued 114,437 shares of its Series B redeemable convertible preferred stock with a fair value of $1.1 million in exchange for the leased facility. No other payments are due under the lease. The common area maintenance and other operating costs are included in the base rent. 100% of the issued shares were initially subject to a repurchase option. Pursuant to the terms of the lease, each month beginning on the one-month anniversary of the commencement date of the lease, 1/36^th of the total shares are released from the repurchase option until all shares are released over the lease period of three years. The scheduled release of shares ceased immediately upon the IPO which was a terminating event.

The Company completed its IPO on May 13, 2019 and as a result, pursuant to the terms of the lease agreement, all previously unvested shares were fully vested and as part of the IPO process, all outstanding shares of the Company’s redeemable convertible preferred stock including the Series B redeemable convertible preferred stock issued in connection with the lease agreement were converted into shares of the Company’s common stock on a 1-for-1 basis and the operating lease liability was extinguished.

In May 2019, the Company entered into an amendment to the lease agreement to rent additional space in the same facility under the same terms as its existing facility lease except the terms of payment. Under the terms of the amendment, the Company paid a one-time fee of approximately $63,000 for the additional space and the lease agreement will terminate in July 2021. No other payments are due under the lease agreement and no renewal option is available. As the entire lease is prepaid, there is no associated lease liability.

In May 2020, the Company entered into a second amendment to the lease agreement to rent additional space in the same facility under the same terms as its existing facility lease except the terms of payment. Under the terms of the amendment, the Company will pay rent monthly for the additional space and the lease agreement will terminate in July 2021. The Company recorded an operating lease asset and liability of $172,000.

The Company believes suitable space will be available before the July 2021 lease termination of its South San Francisco facility.

In May 2020, the Company entered into a lease agreement to rent space in San Diego, California for our clinical operations team. The lease agreement is for three years which commenced August 1, 2020. Total payments under the lease will be $337,000. The Company paid a security deposit of $29,000 and is included in Other Assets on our December 31, 2020 balance sheet. At the commencement of the lease, the Company recorded an operating lease asset of $326,000, which consists of an operating lease liability of $317,000 and cash rent prepayment of $9,000. The Company recognizes lease expense on a straight-line basis over the term of its operating lease. As of December 31, 2020, future rent expense of $596,000 will be recognized over the remaining terms of 7 to 31 months on a straight-line basis over the respective lease period.

Clinical Equipment Operating Lease

The Company uses certain vendor supplied equipment in connection with its on-going clinical trial. The Company has analyzed the vendor agreement and determined that it contains an embedded operating lease. The Company recognizes monthly the leases costs in our research and development expenses. The right of use asset and lease liability are recognized at the lease commencement date based on the present value of lease payments over the lease term. The Company’s lease does not provide an implicit rate. The Company used an adjusted historical incremental borrowing rate, based on the information available at the approximate lease commencement date, to determine the present value of lease payments. The remaining lease expense of $79,000 will be recognized over the remaining lease term of approximately 20 months.

Clinical Equipment Financing Lease

The Company uses certain vendor supplied equipment in connection with its on-going clinical trial. The Company has analyzed the vendor agreements and determined that they contain embedded finance leases. The Company recognizes the depreciation expense in research and development expenses in the statements of operations and comprehensive loss and recognizes expense on a straight-line basis starting when the equipment is placed into service until the end of the contract term ranging from 20 to 34 months. Depreciation expense of the financing lease right of use asset for the years ended December 31, 2020, 2019 and 2018 were $230,000, $107,000, and $0, respectively.

Supplemental balance sheet information related to leases as follows (in thousands except lease terms and discount rates):

		December 31, 2020			December 31, 2019
Operating lease right of use asset, net	$		674		$	625
Short-term operating lease liability			238				—
Long-term operating lease liability			208				—
	$		446		$		—

Finance lease right of use asset			557				559
Finance lease accumulated amortization			(337	)			(107	)
Total finance lease right of use asset, net	$		220		$		452

Weighted average remaining lease term
Operating leases		1.6 years				1.6 years
Finance leases		0.9 years				2.1 years

Weighted average discount rate
Operating leases			2.10	%			—	%
Finance leases			—	%			—	%

Year ended December 31,		Operating Lease
2021			245
2022			141
2023			70
Total lease payments			456
Less: imputed interest			(10	)
Total remaining lease liability			446

Lease costs for the years ended December 31, 2020 and 2019 were approximately:

	Years ended December 31,
	2020		2019
Lease costs:
Finance lease amortization of right of use assets	$	230	$	107
Operating lease costs		578		374
Short-term lease costs		92		11
Total lease costs	$	900	$	492

For the year ended December 31, 2018, rent expense under operating leases computed under the previous accounting method, ASC 840, Leases, was approximately $387,000.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 7. Commitments and Contingencies

Legal Matters

The Company’s industry is characterized by frequent claims and litigation, including claims regarding intellectual property. As a result, the Company may be subject to various legal proceedings from time to time. The results of any future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. Management is not aware of any pending or threatened litigation.

Indemnification

As permitted under Delaware law and in accordance with the Company’s bylaws, the Company is required to indemnify its officers and directors for certain events or occurrences while the officer or director is or was serving in such capacity. The Company is also party to indemnification agreements with its directors. The Company believes the fair value of the indemnification rights and agreements is minimal. Accordingly, the Company has not recorded any liabilities for these indemnification rights and agreements as of December 31, 2020 and 2019.

Contingencies

From time to time, we may have certain contingent liabilities that arise in the ordinary course of our business activities. We accrue a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated.

Common Stock and Common Stock Warrant

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Common Stock and Common Stock Warrant

Note 8. Common Stock and Common Stock Warrant

Common Stock

The Company had reserved shares of common stock for future issuance as follows:

	December 31,
	2020		2019
Options issued and outstanding under the 2019 Stock Plan		5,465,327		2,393,934
Shares available for issuance under 2019 Stock Plan		269,353		2,439,779
Shares available for issuance under the Employee Stock Purchase Plan		536,989		268,295
Total		6,271,669		5,102,008

The Company is authorized to issue 100,000,000 shares of common stock with a par value of $0.001 per share. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when and if declared by the board of directors, subject to the prior rights of holders of any preferred stock that may be outstanding at the time. The Company has never declared any dividends on common stock. As of December 31, 2020, and 2019, the Company had 29,543,222 and 26,869,413 shares of common stock issued and outstanding, respectively.

Common Stock Warrant

In June 2014, in connection with a research grant and license agreement, the Company issued a warrant to purchase 27,941 shares of common stock at $0.03 per share. The grant date estimated fair value of such warrants was insignificant. The warrant was immediately exercisable and expires in June 2024. The warrant was fully exercised in May 2019.

Equity Incentive Plans

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity Incentive Plans

Note 9. Equity Incentive Plans

On December 4, 2014, the Company’s stockholders approved the 2014 Stock Plan (“2014 Plan”), and most recently amended the 2014 Plan on April 25, 2019. The 2014 Plan was amended, restated and re-named the 2019 Equity Incentive Plan (the “2019 Plan”), which became effective as of May 7, 2019, the day prior to the effectiveness of the registration statement filed in connection with the IPO. The remaining shares available for issuance under the 2014 Plan were added to the shares reserved for issuance under the 2019 Plan.

The 2019 Plan provides for the grant of stock options (including incentive stock options and non-qualified stock options), stock appreciation rights, restricted stock, RSUs, performance units, and performance shares to the Company’s employees, directors, and consultants. The maximum aggregate number of shares that may be issued under the 2019 Plan is 5,131,549 shares of the Company’s common stock. In addition, the number of shares available for issuance under the 2019 Plan will be annually increased on the first day of each of its fiscal years beginning with fiscal 2020, by an amount equal to the least of (i) 2,146,354 shares of common stock; (ii) 4% of the outstanding shares of its common stock as of the last day of its immediately preceding fiscal year; and (iii) such other amount as the Company’s Board of Directors may determine.

The 2019 Plan may be amended, suspended or terminated by the Company’s Board of Directors at any time, provided such action does not impair the existing rights of any participant, subject to stockholder approval of any amendment to the 2019 Plan as required by applicable law or listing requirements. Unless sooner terminated by the Company’s Board of Directors, the 2019 Plan will automatically terminate on April 23, 2029.

As of December 31, 2020, the Company had 269,353 shares available for future issuance under the 2019 Plan.

Stock Options

Activity for service-based stock options under the 2019 Plan is as follows:

	Number of Options and Unvested Shares			Weighted Average Exercise Price		Weighted average remaining contractual life (years)		Aggregate intrinsic value
								(In thousands)
Balance at December 31, 2017		769,409		$	0.39	8.89		$	1,108
Options granted		1,316,342		2.08		—		—
Options exercised		(51,350	)	0.46		—		—
Options cancelled / forfeited		(148,897	)	0.41		—		—
Balance at December 31, 2018		1,885,504		$	1.57	9.07		$	1,253
Options granted		932,639			15.87	—		—
Options exercised		(194,279	)		0.51	—		—
Options cancelled / forfeited		(229,930	)		21.09	—		—
Balance at December 31, 2019		2,393,934		$	5.35		8.62	$	121,593
Options granted		2,798,645			42.95	—		—
Options exercised		(173,809	)		7.38	—		—
Options cancelled / forfeited		(228,443	)		42.56	—		—
Balance at December 31, 2020		4,790,327		$	25.47	8.69		$	49,723
Options vested and expected to vest to December 31, 2020		4,790,327			25.47	8.69			49,723
Options exercisable at December 31, 2020		1,471,526		$	10.32	7.64		$	30,633

Aggregate intrinsic value represents the difference between the Company’s estimated fair value of its common stock as of their respective balance sheet dates and the exercise price of outstanding options. The total intrinsic value of options exercised was $6,697,000, $887,000 and $91,000 for the years ended December 31, 2020, 2019 and 2018, respectively. The weighted-average grant date fair value of options granted during the years ended December 31, 2020, 2019 and 2018 was $31.21, $11.11 and $1.26 per share, respectively. The total estimated grant date fair value of options vested during the years ended December 31, 2020, 2019, and 2018 was $10.5 million, $1.2 million, and $0.1 million, respectively.

In 2020, 2019 and 2018, the Company recognized $14,267,000, $2,056,000, and $155,000 respectively, of stock-based compensation expense related to options granted to employees and non-employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the statement of operations for stock-based compensation arrangements. As of December 31, 2020, total unamortized employee stock-based compensation was $72.7 million, which is expected to be recognized over the remaining estimated vesting period of 1.72 years.

Performance Stock Options (“PSOs”)

In December 2020, the Company granted 675,000 performance stock options (“PSOs”) under the Stock Incentive Plan to its executive and senior officers. Vesting for the options is performance based and is based on continued employment at the vesting date, with the options vesting in two installments if the Company’s average closing price in any 45 consecutive trading day period exceeds a certain amount per share prior to March 15, 2023 and March 15, 2024, respectively. PSOs represent a contingent right to purchase Common Stock upon achievement of specified market conditions.

The Company recognized stock-based compensation expense of $203,000 in 2020 relating to these PSOs. The weighted-average grant date fair value of the PSOs granted during 2020 was $14.90 per share. As of December 31, 2020, total unamortized stock-based compensation related to PSOs was $9,854,000, which is expected to be recognized over the remaining estimated vesting period of 2.75 years. Total intrinsic value for PSOs outstanding was $0 for the year ended December 31, 2020.

The following table summarizes activity under the Company’s PSOs from the 2019 Plan and related information:

	Shares Subject to Outstanding PSOs		Weighted Average Exercise Price		Weighted average remaining contractual life (years)
Balance at December 31, 2019	—		—		—
Options granted		675,000		29.60	—
Options exercised	—		—		—
Options cancelled	—		—		—
Balance at December 31, 2020		675,000		29.60		9.94
Outstanding		675,000	$	29.60		9.94
Vested	—		—		—

Stock-Based Compensation Expense

The following table summarizes employee and non-employee stock-based compensation expense for the years ended December 31, 2020, 2019 and 2018 and the allocation within the statements of operations and comprehensive loss (in thousands):

	2020		2019		2018
General and administrative expense	$	7,441	$	1,378	$	78
Research and development expense		7,029		678		77
Total stock-based compensation	$	14,470	$	2,056	$	155

The Company estimates the fair value of its service-based stock option awards utilizing the Black-Scholes option pricing model, which is dependent upon several variables, such as expected term, volatility, risk-free interest rate, and expected dividends. Each of these inputs is subjective and generally requires significant judgment to determine. Stock-based compensation is measured at the grant date based on the fair value of the award and is recognized as expense, over the requisite service period, which is generally the vesting period of the respective award. The Company recognizes compensation on a straight-line basis over the requisite vesting period for each award. Forfeitures are recognized as they occur. The following weighted average assumptions were used to calculate the fair value of stock-based compensation for the years ended December 31, 2020, 2019 and 2018:

	2020			2019			2018
Expected volatility		86.69	%		80.19	%		69.6	%
Expected dividend yield		—	%		—	%		—	%
Expected term (in years)	6.23			6.25			6.25
Risk-free interest rate		0.80	%		1.90	%		2.91	%

Expected Term — The Company has opted to use the “simplified method” for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option (generally 10 years).

Expected Volatility—Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of its own stock and the stock of companies within its defined peer group. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards.

Risk-Free Interest Rate — The risk-free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of the Company’s stock options.

Expected Dividend — The Company has not issued any dividends in its history and does not expect to issue dividends over the life of the options and therefore has estimated the dividend yield to be zero.

Fair value of Common Stock — The fair value of the shares of common stock underlying the stock-based awards has historically been determined by the board of directors, with input from management. Prior to the Company’s IPO, there has been no public market for the Company’s common stock, the board of directors determined the fair value of the common stock on the grant-date of the stock-based award by considering a number of objective and subjective factors, including enterprise valuations of the Company’s common stock performed by an unrelated third-party specialist, valuations of comparable companies, sales of the Company’s redeemable convertible preferred stock to unrelated third parties, operating and financial performance, the lack of liquidity of the Company’s capital stock, and general and industry-specific economic outlook. Subsequent to the IPO date, the board of directors uses the closing price of stock on the date of grant to determine the fair value. The board of directors intends all options granted to be exercisable at a price per share not less than the estimated per share fair value of common stock underlying those options on the date of grant.

The Company estimated the grant date fair value of its market-based performance stock option awards granted during the year ended December 31, 2020 using a Monte Carlo Simulation method by applying the following assumptions:

Expected share price volatility		95.0	%
Contractual term, in years	10
Risk-free interest rate		0.90	%

Employee Stock Purchase Plan

On April 24, 2019, the Company’s Board of Directors adopted its 2019 Employee Stock Purchase Plan (“2019 ESPP”), which was subsequently approved by the Company’s stockholders and became effective on May 7, 2019, the day immediately prior to the effectiveness of the registration statement filed in connection with the IPO. The 2019 ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Internal Revenue Code (the “Code”) for U.S. employees. In addition, the 2019 ESPP authorizes grants of purchase rights that do not comply with Section 423 of the Code under a separate non-423 component for non-U.S. employees and certain non-U.S. service providers. The Company has reserved 268,295 shares of common stock for issuance under the 2019 ESPP. In addition, the number of shares reserved for issuance under the 2019 ESPP will be increased automatically on the first day of each fiscal year for a period of up to ten years, starting with the 2020 fiscal year, by a number equal to the lesser of: (i) 536,589 shares; (ii) 1% of the shares of common stock outstanding on the last day of the prior fiscal year; or (iii) such lesser number of shares determined by the Company’s Board of Directors. The 2019 ESPP is expected to be implemented through a series of offerings under which participants are granted purchase rights to purchase shares of the Company’s common stock on specified dates during such offerings. The Company has not yet approved an offering under the 2019 ESPP.

Convertible Promissory Notes

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Convertible Promissory Notes

Note 10. Convertible Promissory Notes

In February 2017 the Company received $7.6 million from the issuance of convertible promissory notes to the Company’s current investors. In June 2017 the Company received an additional $150,000 from an issuance under the same note facility to a new investor. In January 2018 the Company received $250,000 from a new investor under the same note facility for a total of $8.0 million in principal value under the note facility. The notes accrue simple interest on the outstanding principal amount at the rate of 8% per annum and were set to mature on February 1, 2019.

The convertible promissory notes have conversion and repayment options as follows: (a) in the event that the Company has an equity financing event of at least $10 million to new investors on or before the maturity date, then the outstanding principal amount of this convertible promissory note and any unpaid accrued interest will automatically convert in whole into equity securities sold in the qualified financing at a conversion price equal to 80% of the cash price paid per share for equity securities by the investors in the qualified financing, or (b) the Company consummates a merger of the Company where it does not maintain majority voting power or conducts a sale, lease, transfer, exclusive license or other disposition of all or substantially all of its assets while the convertible promissory notes remain outstanding, the Company shall repay the holders in cash in an amount equal to 200% of the outstanding principal and accrued interest amount of the convertible promissory notes.

The Company evaluated its convertible notes and determined that the redemption premium feature qualified as a derivative liability to be separately accounted for in accordance with ASC 815. The convertible promissory notes contained put options as follows:

On or before the maturity date, the principal and accrued interest of the notes will automatically convert into equity securities issued and sold in the initial closing of the Company’s next qualified equity financing with gross proceeds of at least $10,000,000, exclusive of the conversion of the notes. The number of shares to be issued to the note holders will be equal to dividing the outstanding principal and any unpaid accrued interest by 80% of the price paid per share of the next equity security sold to investors. The discount in share price to note holders is not considered clearly and closely related to the debt host and results in an embedded derivative that must be bifurcated and accounted for separately from the debt host.

In the event of a merger or sale, lease, transfer, exclusive license or other disposition of all or substantially all of its assets prior to repayment, the outstanding principal and unpaid accrued interest will be repaid in cash, plus a repayment premium equal to 100% of the outstanding principal and accrued interest at the time of the merger or sale of assets. The premium to note holders is not considered clearly and closely related to the debt host and results in an embedded derivative that must be bifurcated and accounted for separately from the debt host.

Accordingly, upon the issuance of the February 2017 convertible promissory notes, the estimated fair value of the embedded derivative liability was determined using a bond plus option valuation model and assuming a probability of 80% that a qualified financing would occur and a zero probability that a merger or sale would occur. The Company recorded the estimated fair value of these put options (embedded derivatives) as a liability of $1.55 million with an offsetting amount recorded as debt discount, which offsets the carrying amount of the debt. The debt discount is amortized over the debt’s expected term. The derivative liability is revalued at the end of each reporting period and any change in fair value is recognized in other income.

Upon the issuance of the June 2017 convertible promissory notes, the estimated fair value of the embedded derivatives were determined using a bond plus option valuation model and assuming a probability of 80% that a qualified financing would occur and a zero probability that a sale or merger would occur. The Company recorded the estimated fair value of these put options (embedded derivatives) as a liability of $30,000 with an offsetting amount recorded as debt discount, which offsets the carrying amount of the debt.

Upon issuance of the January 2018 convertible promissory notes, the estimated fair value of the embedded derivatives was determined using a bond plus option valuation model and assuming a probability of 90% that a qualified financing would occur and a zero probability that a merger or sale would occur. The Company recorded the estimated fair value of these put options (embedded derivatives) as a liability of $56,250 with an offsetting amount recorded as debt discount, which offsets the carrying amount of the debt.

The derivative liability is revalued at the end of each reporting period and any change in fair value is recognized in “Change in fair value of redemption premium liability” in the Statement of Operations.

In May 2018, the notes converted into 1,147,205 shares of the Company’s Series B redeemable convertible preferred stock in conjunction with the Company’s Series B redeemable convertible preferred stock financing (the “Series B Financing”), which was considered a Qualified Financing under the terms of the notes. In conjunction with the closing, the holders of the notes also converted their accrued and unpaid interest of $0.8 million and the Company recorded a change in the fair value of the derivative liability of $206,000.

Related Party Transactions

12 Months Ended

Dec. 31, 2020

Related Party Transactions

Note 11. Related Party Transactions

In June 2014, the Company entered into a research grant and license agreement (the Agreement) with a stockholder of the Company. The Agreement requires the Company to pay royalties to the stockholder in the amount of 3% of gross revenues not to exceed $1.05 million. This agreement was amended in April 2019 and the royalty payment provision was removed.

As described in Note 1, on February 10, 2020, the Company issued and sold shares of common stock at a purchase price of $50.00 per share in a private placement. In the private placement, the Company issued and sold 30,000 shares of common stock for an aggregate purchase price of $1,500,000 to an entity affiliated with David A. Lamond, a member of the Company’s Board of Directors.

On January 13, 2021, the Company entered into an agreement with LifeSci Advisors, LLC for investor relations consulting services. The Company’s Chief Operating Officer and Chief Financial Officer, Christopher Lowe, has an investment in a sister entity to LifeSci Advisors, LLC whose business is unrelated to the services being offered by LifeSci Advisors, LLC to the Company. The Company will pay $180,000 to LifeSci Advisors, LLC over the one-year term of the agreement.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

Note 12. Income taxes

From inception through 2020, the Company has only generated pretax losses in the United States and has not generated any pretax income or loss outside of the United States. The Company did not record a provision (benefit) for income taxes for the years ended December 31, 2020, 2019 and 2018.

The provision for income taxes differs from the amount expected by applying the federal statutory rate to the loss before taxes as follows:

	Year ended December 31,
	2020				2019				2018
Federal statutory income tax rate		21.00		%		21.00		%		21.00		%
State income taxes		0.55				(1.12	)		6.24
Income tax credits		2.14				3.67				—
Non-deductible expenses and others		0.44				(0.38	)			(1.02	)
Non-deductible expenses related to the convertible promissory notes		—				—				(1.96	)
Change in valuation allowance		(24.13	)			(23.17	)			(24.26	)
		—		%		—		%		—		%

As of December 31, 2020 and 2019, the components of the Company’s deferred tax assets are as follows (in thousands):

	Year ended December 31,
	2020			2019
Deferred tax asset:
Federal and State net operating loss carryforwards	$	28,072		$	14,219
Stock based compensation		2,633			238
Other accruals and deferred expense		566			185
Tax credits		3,928			1,867
Gross deferred tax asset		35,199			16,509
Valuation allowance		(35,034	)		(16,489	)
Total deferred tax assets		165			20
Deferred tax liabilities:
Property and equipment		(14	)		(20	)
Capitalized leases		(151	)		—
Gross deferred tax liabilities		(165	)		(20	)
Net deferred tax assets	$	—		$	—

Deferred income taxes reflect the net tax effects of (a) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, and (b) operating losses and tax credit carryforwards.

The Company’s accounting for deferred taxes involves the evaluation of a number of factors concerning the realizability of its net deferred tax assets. The Company primarily considered such factors as its history of operating losses, the nature of the Company’s deferred tax assets, and the timing, likelihood and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible. At present, the Company does not believe that it is more likely than not that the deferred tax assets will be realized; accordingly, a full valuation allowance has been established and no deferred tax asset is shown in the accompanying balance sheets. The valuation allowance increased by approximately $18.5 million and $8.5 million and $3.0 million respectively for the years ended December 31, 2020, 2019 and 2018.

At December 31, 2020, the Company has federal net operating loss carryforwards of approximately $128.2 million of which $112.3 million will not expire and $15.9 million begin expiring in 2034. The Company also has state net operating loss carryforwards of approximately $4.9 million which begin to expire in 2034. Additionally, the Company has federal tax credits of approximately $4.9 million which begin to expire in 2036 and state tax credits of approximately $1.1 million which do not expire.

Use of the net operating loss and credit carryforwards may be subject to a substantial annual limitation due to the ownership change provisions of U.S. tax law and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before use.

Pursuant to the Internal Revenue Code, as amended (the “Code”) Sections 382 and 383, annual use of a company’s NOL and research and development credit carryforwards may be limited if there is a cumulative change in ownership of greater than 50% within a three-year period. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. If limited, the related tax asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. The Company has not completed such an analysis pursuant to Sections 382 and 383 and therefore has established a valuation allowance as the realization of such deferred tax assets has not met the more likely than not threshold requirement. Due to the existence of the valuation allowance, further changes in the Company’s unrecognized tax benefits will not impact the Company’s effective tax rate.

Uncertain Tax Positions

The Company follows the provisions of the FASB ASC 740-10, Accounting for Uncertainty in Income Taxes. ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of uncertain tax positions that have been taken or expected to be taken on a tax return. No liability related to uncertain tax positions is recorded in the financial statements.

The Company is subject to taxation in the United States. Because of the net operating loss and research credit carryforwards, all of the Company’s tax years, from 2013 to 2020, remain open to U.S. federal, California, and other state tax examinations. There were no interest or penalties accrued at December 31, 2020, 2019 and 2018.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	Year ended December 31,
	2020		2019		2018
Beginning balance	$	1,059	$	356	$	171
Additions for tax positions taken in a prior year		—		168	—
Additions for tax positions taken in a current year		917		535		185
Ending balance	$	1,976	$	1,059	$	356

On March 27, 2020, President Trump signed the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") into law. The Company has reviewed the aspects of this law as it relates to income taxes and have concluded that at this time, the CARES Act will have no material impact to the Company’s 2020 provision for 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

Note 13. Net Loss per Share

The following table sets forth the computation of basic and diluted net loss per share (in thousands except for share and per share amounts):

	December 31,
	2020			2019			2018
Numerator:
Net loss	$	(76,849	)	$	(36,980	)	$	(12,476	)
Denominator
Weighted average common shares outstanding		29,176,232			19,031,940			3,362,192
Net loss per share, basic and diluted	$	(2.63	)	$	(1.94	)	$	(3.71	)

The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share for the periods presented because including them would have been antidilutive:

	December 31,
	2020		2019		2018
Series A convertible preferred stock		—		—		9,008,919
Series B convertible preferred stock		—		—		9,152,108
Stock options issued and outstanding		4,790,327		2,393,934		1,885,504
Performance stock options		675,000		—		—
Warrants		—		—		27,941
		5,465,327		2,393,934		20,074,472

Employee Benefit Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

Employee Benefit Plan

Note 14. Employee Benefit Plan

The Company sponsors a 401(k) defined contribution plan for its employees. This plan provides for pre-tax and post-tax contributions for all employees. Employee contributions are voluntary. Employees may contribute up to 100% of their annual compensation to this plan, as limited by an annual maximum amount as determined by the Internal Revenue Service. The Company may match employee contributions, and may make profit sharing contributions, in amounts to be determined at the Company’s sole discretion. The Company made no contributions to the plan for the years ended December 31, 2020, 2019, and 2018, respectively.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Risk and Uncertainties

Segments

Cash, Cash Equivalents and Investments

Property and Equipment, Net

The useful lives of property and equipment are as follows:

Computer equipment	3 years
Lab equipment	5 years
Finance lease right of use assets	Shorter of estimated useful life or lease term
Leasehold improvement	Shorter of estimated useful life or lease term
Office furniture	3 years

Concentration of Credit Risk

Impairment of Long-Lived Assets

Leases

Research and Development Expenses

•

fees paid to Contract Research Organizations, or CROs, in connection with clinical studies;

•

fees paid to investigative sites in connection with clinical studies;

•

fees paid to contract manufacturers in connection with the production of clinical study materials; and

•

fees paid to vendors in connection with preclinical development activities.

Patents Costs

Patent Costs

The Company has no historical data to support a probable future economic benefit for the arising patent applications, filing and prosecution costs. Therefore, patent costs are expensed as incurred.

Stock-Based Compensation

Redeemable Convertible Preferred Stock

Income Taxes

The Company includes any penalties and interest expense related to income taxes as a component of other expense and interest expense, net, as necessary.

Comprehensive Income (Loss)

Net Loss per Share

Recently Accounting Pronouncements Adopted and Recent Accounting Pronouncements Not Yet Adopted

Recent Accounting Pronouncements Adopted

Recent Accounting Pronouncements Not Yet Adopted

The following are new accounting pronouncements that the Company is evaluating for future impacts on its financial statements:

All other newly issued accounting pronouncements not yet effective have been deemed either immaterial or not applicable.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Useful Lives of Property and Equipment

The useful lives of property and equipment are as follows:

Computer equipment	3 years
Lab equipment	5 years
Finance lease right of use assets	Shorter of estimated useful life or lease term
Leasehold improvement	Shorter of estimated useful life or lease term
Office furniture	3 years

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities to Fair Value Measurements on Recurring Basis

	Fair Value Measurements at December 31, 2020
	Total		Level 1		Level 2		Level 3
Money market funds	$	15,661	$	15,661	$	—	$	—
Certificates of Deposit		30,765		—		30,765		—
Repurchase Agreements		15,000		—		15,000
Corporate notes		75,426		—		75,426		—
Government and agency notes		8,296		—		8,296		—
Municipal notes		3,446		—		3,446		—
Total	$	148,594	$	15,661	$	132,933	$	—

	Fair Value Measurements at December 31, 2019
	Total		Level 1		Level 2		Level 3
Money market funds	$	30,054	$	30,054	$	—	$	—
Certificates of Deposit		20,046		—		20,046		—
Repurchase Agreements		15,000		—		15,000		—
Corporate notes		38,783		—		38,783		—
Government notes		7,574		—		7,574		—
Commercial Paper		1,096		—		1,096		—
Total	$	112,553	$	30,054	$	82,499	$	—

Cash, Cash Equivalents and Investments (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Fair Values of Cash, Cash Equivalents, and Short-Term Investments Measured at Fair Value on Recurring Basis

	December 31,
	2020		2019
Cash and cash equivalents:
Cash	$	35,690	$	4,074
Money market funds		15,661		30,054
Repurchase agreements		15,000		15,000
Certificates of deposit		490		985
Corporate notes		—		1,101
Total cash and cash equivalents	$	66,841	$	51,214

Short-term investments:
Commercial paper	$	—	$	1,096
Certificates of deposit		23,387		15,428
Municipal notes		2,365		—
Corporate notes		34,991		24,552
Government and agency notes		6,236		7,574
Total short-term investments	$	66,979	$	48,650

Long-term investments
Corporate notes	$	40,435	$	13,130
Certificates of deposit		6,888		3,633
Municipal notes		1,081		—
Government and agency notes		2,060		—
Total long-term investments	$	50,464	$	16,763

Summary of Available-for-Sale Securities

The following table summarizes the available-for-sale securities (in thousands):

	Fair Value Measurements at December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	15,661	$	—	$	—		$	15,661
Certificates of Deposit		30,603		162		—			30,765
Repurchase Agreements		15,000		—		—			15,000
Corporate notes		75,298		183		(55	)		75,426
Government and agency notes		8,274		22		—			8,296
Municipal notes		3,445		1		—			3,446
Total cash equivalents and investments	$	148,281	$	368	$	(55	)	$	148,594

Classified as:
Cash equivalents (maturities within 90 days)								$	31,151
Short-term investments (maturities within one year)									66,979
Long-term investments (maturities beyond 1 year)									50,464
Total cash equivalents and investments								$	148,594

	Fair Value Measurements at December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Money market funds	$	30,054	$	—	$	—		$	30,054
Certificates of Deposit		19,992		54		—			20,046
Repurchase Agreements		15,000		—		—			15,000
Corporate notes		38,788		—		(5	)		38,783
Government notes		7,563		11					7,574
Commercial Paper		1,096		—		—			1,096
Total cash equivalents and investments	$	112,493	$	65	$	(5	)	$	112,553

Classified as:
Cash equivalents (maturities within 90 days)								$	47,140
Short-term investments (maturities within one year)									48,650
Long-term investments (maturities beyond 1 year)									16,763
Total cash equivalents and investments								$	112,553

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Components [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

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

	December 31,
	2020		2019
Prepaid expenses	$	274	$	129
Prepaid insurance		964		858
Prepaid research and development expenses		2,110		4,517
Other current assets		694		688
Total prepaid expenses and other current assets	$	4,042	$	6,192

Schedule of Property and Equipment, Net

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

	December 31,
	2020			2019
Computer equipment	$	33		$	28
Lab equipment		405			405
Finance lease right of use assets		557			559
Leasehold improvement		21			—
Office furniture		26			—
Less: accumulated amortization and depreciation		(615	)		(283	)
Property and equipment, net	$	427		$	709

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Personnel expenses	$	2,415	$	1,261
Professional fees		141		96
Research and development expenses		10,603		4,410
Other		282		50
Total accrued expenses and other current liabilities	$	13,441	$	5,817

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Supplemental Balance Sheet Information Related To Leases

Supplemental balance sheet information related to leases as follows (in thousands except lease terms and discount rates):

		December 31, 2020			December 31, 2019
Operating lease right of use asset, net	$		674		$	625
Short-term operating lease liability			238				—
Long-term operating lease liability			208				—
	$		446		$		—

Finance lease right of use asset			557				559
Finance lease accumulated amortization			(337	)			(107	)
Total finance lease right of use asset, net	$		220		$		452

Weighted average remaining lease term
Operating leases		1.6 years				1.6 years
Finance leases		0.9 years				2.1 years

Weighted average discount rate
Operating leases			2.10	%			—	%
Finance leases			—	%			—	%

Year ended December 31,		Operating Lease
2021			245
2022			141
2023			70
Total lease payments			456
Less: imputed interest			(10	)
Total remaining lease liability			446

Summary of Lease Costs

Lease costs for the years ended December 31, 2020 and 2019 were approximately:

	Years ended December 31,
	2020		2019
Lease costs:
Finance lease amortization of right of use assets	$	230	$	107
Operating lease costs		578		374
Short-term lease costs		92		11
Total lease costs	$	900	$	492

Common Stock and Common Stock Warrant (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Future Issuance

The Company had reserved shares of common stock for future issuance as follows:

	December 31,
	2020		2019
Options issued and outstanding under the 2019 Stock Plan		5,465,327		2,393,934
Shares available for issuance under 2019 Stock Plan		269,353		2,439,779
Shares available for issuance under the Employee Stock Purchase Plan		536,989		268,295
Total		6,271,669		5,102,008

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Employee and Non-Employee Stock-Based Compensation Expense

	2020		2019		2018
General and administrative expense	$	7,441	$	1,378	$	78
Research and development expense		7,029		678		77
Total stock-based compensation	$	14,470	$	2,056	$	155

Service Based Stock Options

Summary of Stock Option Activity

Activity for service-based stock options under the 2019 Plan is as follows:

	Number of Options and Unvested Shares			Weighted Average Exercise Price		Weighted average remaining contractual life (years)		Aggregate intrinsic value
								(In thousands)
Balance at December 31, 2017		769,409		$	0.39	8.89		$	1,108
Options granted		1,316,342		2.08		—		—
Options exercised		(51,350	)	0.46		—		—
Options cancelled / forfeited		(148,897	)	0.41		—		—
Balance at December 31, 2018		1,885,504		$	1.57	9.07		$	1,253
Options granted		932,639			15.87	—		—
Options exercised		(194,279	)		0.51	—		—
Options cancelled / forfeited		(229,930	)		21.09	—		—
Balance at December 31, 2019		2,393,934		$	5.35		8.62	$	121,593
Options granted		2,798,645			42.95	—		—
Options exercised		(173,809	)		7.38	—		—
Options cancelled / forfeited		(228,443	)		42.56	—		—
Balance at December 31, 2020		4,790,327		$	25.47	8.69		$	49,723
Options vested and expected to vest to December 31, 2020		4,790,327			25.47	8.69			49,723
Options exercisable at December 31, 2020		1,471,526		$	10.32	7.64		$	30,633

Summary of Weighted Average Assumptions to Calculate the Fair Value of Stock-Based Compensation

The following weighted average assumptions were used to calculate the fair value of stock-based compensation for the years ended December 31, 2020, 2019 and 2018:

	2020			2019			2018
Expected volatility		86.69	%		80.19	%		69.6	%
Expected dividend yield		—	%		—	%		—	%
Expected term (in years)	6.23			6.25			6.25
Risk-free interest rate		0.80	%		1.90	%		2.91	%

Performance Stock Options

Summary of Stock Option Activity

The following table summarizes activity under the Company’s PSOs from the 2019 Plan and related information:

	Shares Subject to Outstanding PSOs		Weighted Average Exercise Price		Weighted average remaining contractual life (years)
Balance at December 31, 2019	—		—		—
Options granted		675,000		29.60	—
Options exercised	—		—		—
Options cancelled	—		—		—
Balance at December 31, 2020		675,000		29.60		9.94
Outstanding		675,000	$	29.60		9.94
Vested	—		—		—

Market Based Performance Stock Options

Summary of Weighted Average Assumptions to Calculate the Fair Value of Stock-Based Compensation

Expected share price volatility		95.0	%
Contractual term, in years	10
Risk-free interest rate		0.90	%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Provision for Income Taxes Differs From the Amount Expected by Applying the Federal Statutory Rate to Loss Before Taxes

The provision for income taxes differs from the amount expected by applying the federal statutory rate to the loss before taxes as follows:

	Year ended December 31,
	2020				2019				2018
Federal statutory income tax rate		21.00		%		21.00		%		21.00		%
State income taxes		0.55				(1.12	)		6.24
Income tax credits		2.14				3.67				—
Non-deductible expenses and others		0.44				(0.38	)			(1.02	)
Non-deductible expenses related to the convertible promissory notes		—				—				(1.96	)
Change in valuation allowance		(24.13	)			(23.17	)			(24.26	)
		—		%		—		%		—		%

Schedule of Components of Deferred Tax Assets

As of December 31, 2020 and 2019, the components of the Company’s deferred tax assets are as follows (in thousands):

	Year ended December 31,
	2020			2019
Deferred tax asset:
Federal and State net operating loss carryforwards	$	28,072		$	14,219
Stock based compensation		2,633			238
Other accruals and deferred expense		566			185
Tax credits		3,928			1,867
Gross deferred tax asset		35,199			16,509
Valuation allowance		(35,034	)		(16,489	)
Total deferred tax assets		165			20
Deferred tax liabilities:
Property and equipment		(14	)		(20	)
Capitalized leases		(151	)		—
Gross deferred tax liabilities		(165	)		(20	)
Net deferred tax assets	$	—		$	—

Schedule of Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	Year ended December 31,
	2020		2019		2018
Beginning balance	$	1,059	$	356	$	171
Additions for tax positions taken in a prior year		—		168	—
Additions for tax positions taken in a current year		917		535		185
Ending balance	$	1,976	$	1,059	$	356

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share

The following table sets forth the computation of basic and diluted net loss per share (in thousands except for share and per share amounts):

	December 31,
	2020			2019			2018
Numerator:
Net loss	$	(76,849	)	$	(36,980	)	$	(12,476	)
Denominator
Weighted average common shares outstanding		29,176,232			19,031,940			3,362,192
Net loss per share, basic and diluted	$	(2.63	)	$	(1.94	)	$	(3.71	)

Schedule of Outstanding Potentially Dilutive Ordinary Shares Excluded from Calculation of Diluted Net Loss Per Share

	December 31,
	2020		2019		2018
Series A convertible preferred stock		—		—		9,008,919
Series B convertible preferred stock		—		—		9,152,108
Stock options issued and outstanding		4,790,327		2,393,934		1,885,504
Performance stock options		675,000		—		—
Warrants		—		—		27,941
		5,465,327		2,393,934		20,074,472

Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	May 13, 2019	Feb. 29, 2020	Dec. 31, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Entity incorporation date			2012-06
Proceeds from issuance of common stock, net of underwriting discounts and commissions and offering expenses				$ 77,827
Accumulated deficit			$ (146,654)	(69,805)
Cash, cash equivalents, and short-term investments			133,800
Long term investments			$ 50,464	$ 16,763
IPO
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of stock (in shares)	5,073,800
Public offering price per share	$ 17.00
Proceeds from issuance of common stock, net of underwriting discounts and commissions and offering expenses	$ 77,800
Conversion of redeemable convertible preferred stock to common stock	18,161,027		18,161,027
Convertible redeemable preferred stock, shares outstanding			0	0
Underwriters
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of stock (in shares)	661,800
Private Placement
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of stock (in shares)		2,500,000
Public offering price per share		$ 50.00
Agreement date		Feb. 10, 2020
Proceeds from issuance of common stock		$ 125,000
Costs related to offering		$ 7,400

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Segment shares	May 31, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	May 13, 2019 shares	Jan. 01, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segment \| Segment	1
Number of operating segment \| Segment	1
Operating lease asset	$ 674,000	$ 172,000	$ 625,000
Short-term operating lease liability	238,000
Long-term operating lease liability	208,000
Accumulated deficit	$ (146,654,000)		$ (69,805,000)
Percentage of holders demanded on redemption of stock	60.00%
IPO
Summary Of Significant Accounting Policies [Line Items]
Conversion of redeemable convertible preferred stock to common stock \| shares	18,161,027			18,161,027
Convertible redeemable preferred stock, shares outstanding \| shares	0		0
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease asset					$ 900,000
Short-term operating lease liability					300,000
Long-term operating lease liability					600,000
Accounting Standards Update 2016-02 \| Revision of Prior Period, Accounting Standards Update, Adjustment
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit					$ 0
Accounting Standards Update 2018-03
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	false
Accounting Standards Update 2018-15
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	false

Summary of Significant Accounting Policies - Schedule of Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Computer Equipment
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	3 years
Lab Equipment
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	5 years
Finance Lease Right of Use Assets
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	Shorter of estimated useful life or lease term
Leasehold Improvement
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	Shorter of estimated useful life or lease term
Office Furniture
Property Plant And Equipment [Line Items]
Useful lives of property and equipment	3 years

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair value assets level 1 to level 2	$ 0	$ 0
Fair value assets level 2 to level 1	0	0
Fair value assets transfers into level 3	0	0
Fair value assets transfers out of level 3	$ 0	$ 0

Fair Value Measurements - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	$ 148,594	$ 112,553
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	15,661	30,054
Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	30,765	20,046
Repurchase Agreements
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	15,000	15,000
Corporate Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	75,426	38,783
Government and Agency Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	8,296	7,574
Municipal Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	3,446
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities		1,096
Level 1
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	15,661	30,054
Level 1 \| Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	15,661	30,054
Level 2
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	132,933	82,499
Level 2 \| Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	30,765	20,046
Level 2 \| Repurchase Agreements
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	15,000	15,000
Level 2 \| Corporate Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	75,426	38,783
Level 2 \| Government and Agency Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	8,296	7,574
Level 2 \| Municipal Notes
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities	$ 3,446
Level 2 \| Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Financial assets and liabilities		$ 1,096

Cash, Cash Equivalents and Investments - Summary of Fair Values of Cash, Cash Equivalents, and Short-Term Investments Measured at Fair Value on 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]
Total cash and cash equivalents	$ 31,151	$ 47,140
Short term investments	66,979	48,650
Long term investments	50,464	16,763
Fair Value on Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents	66,841	51,214
Short term investments	66,979	48,650
Long term investments	50,464	16,763
Fair Value on Recurring \| Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents	35,690	4,074
Fair Value on Recurring \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents	15,661	30,054
Fair Value on Recurring \| Certificates of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents	490	985
Short term investments	23,387	15,428
Long term investments	6,888	3,633
Fair Value on Recurring \| Repurchase Agreements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents	15,000	15,000
Fair Value on Recurring \| Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash and cash equivalents		1,101
Short term investments	34,991	24,552
Long term investments	40,435	13,130
Fair Value on Recurring \| Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short term investments		1,096
Fair Value on Recurring \| Municipal Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short term investments	2,365
Long term investments	1,081
Fair Value on Recurring \| Government and Agency Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short term investments	6,236	$ 7,574
Long term investments	$ 2,060

Cash, Cash Equivalents and Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Weighted average remaining contractual maturities of available-for-sale securities	10 months
Realized gains or losses on the sale or maturity of available-for-sale securities	$ 0	$ 0	$ 0
Amounts reclassify out of accumulated other comprehensive income	$ 0

Cash, Cash Equivalents and Investments - Summary of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 148,281	$ 112,493
Unrealized Gains	368	65
Unrealized Losses	(55)	(5)
Financial assets and liabilities	148,594	112,553
Cash equivalents (maturities within 90 days)	31,151	47,140
Short-term investments (maturities within one year)	66,979	48,650
Long-term investments (maturities beyond 1 year)	50,464	16,763
Total cash equivalents and investments	148,594	112,553
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	15,661	30,054
Financial assets and liabilities	15,661	30,054
Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	30,603	19,992
Unrealized Gains	162	54
Financial assets and liabilities	30,765	20,046
Repurchase Agreements
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	15,000	15,000
Financial assets and liabilities	15,000	15,000
Corporate Notes
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	75,298	38,788
Unrealized Gains	183
Unrealized Losses	(55)	(5)
Financial assets and liabilities	75,426	38,783
Government and Agency Notes
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	8,274	7,563
Unrealized Gains	22	11
Financial assets and liabilities	8,296	7,574
Municipal Notes
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	3,445
Unrealized Gains	1
Financial assets and liabilities	$ 3,446
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		1,096
Financial assets and liabilities		$ 1,096

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 274	$ 129
Prepaid insurance	964	858
Prepaid research and development expenses	2,110	4,517
Other current assets	694	688
Total prepaid expenses and other current assets	$ 4,042	$ 6,192

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Less: accumulated amortization and depreciation	$ (615)	$ (283)
Property and equipment, net	427	709
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment	33	28
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment	405	405
Finance Lease Right of Use Assets
Property Plant And Equipment [Line Items]
Property and equipment	557	$ 559
Leasehold Improvement
Property Plant And Equipment [Line Items]
Property and equipment	21
Office Furniture
Property Plant And Equipment [Line Items]
Property and equipment	$ 26

Balance Sheet Components - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Depreciation	$ 332,000	$ 188,000	$ 51,000

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Personnel expenses	$ 2,415	$ 1,261
Professional fees	141	96
Research and development expenses	10,603	4,410
Other	282	50
Total accrued expenses and other current liabilities	$ 13,441	$ 5,817

Leases - Additional Information (Details)	1 Months Ended			12 Months Ended
Leases - Additional Information (Details)	May 31, 2020 USD ($)	May 31, 2019 USD ($)	Jun. 30, 2018 USD ($) ft² shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 13, 2019
Lessee Lease Description [Line Items]
Renewal options		false
Operating lease payments		$ 0	$ 0
Repurchase option percentage			100.00%
Operating leases period			3 years
Operating lease payments paid for additional space		$ 63,000
Operating lease termination month and year	2021-07	2021-07
Operating lease liability	$ 172,000	$ 0		$ 446,000
Operating lease asset	$ 172,000			674,000	$ 625,000
Operating lease liability				208,000
Future rent expense				596,000
Depreciation expense of finance lease right-of-use asset				230,000	$ 107,000	$ 0
Operating lease rent expense						$ 387,000
Clinical Equipment
Lessee Lease Description [Line Items]
Remaining lease expense				$ 79,000
Remaining lease term				20 months
Minimum
Lessee Lease Description [Line Items]
Operating lease remaining term on a straight-line basis				7 months
Finance lease amortized period on equipment service				20 months
Maximum
Lessee Lease Description [Line Items]
Operating lease remaining term on a straight-line basis				31 months
Finance lease amortized period on equipment service				34 months
San Diego, California
Lessee Lease Description [Line Items]
Lease agreement period	3 years
Operating lease payments	$ 337,000
Operating lease asset	326,000
Operating lease liability	317,000
Rent prepayment	9,000
San Diego, California \| Other Assets
Lessee Lease Description [Line Items]
Security deposit paid	$ 29,000
Series B Redeemable Convertible Preferred Stock
Lessee Lease Description [Line Items]
Lease agreement period			3 years
Renewal options			false
Area under lease \| ft²			3,185
Shares issued \| shares			114,437
Convertible preferred stock, fair value			$ 1,100,000
Series B Redeemable Convertible Preferred Stock \| IPO
Lessee Lease Description [Line Items]
Conversion of redeemable convertible preferred stock to common stock ratio							100.00%

Leases - Supplemental Balance Sheet Information Related to Leases (Details) - USD ($)	Dec. 31, 2020	May 31, 2020	Dec. 31, 2019	May 31, 2019
Leases [Abstract]
Operating lease right-of-use assets, net	$ 674,000	$ 172,000	$ 625,000
Short-term operating lease liability	$ 238,000
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Long-term operating lease liability	$ 208,000
Operating lease liability	446,000	172,000		$ 0
Finance lease right of use asset	557,000		559,000
Finance lease accumulated amortization	(337,000)		(107,000)
Total finance lease right of use asset, net	$ 220,000		$ 452,000
Weighted average remaining lease term
Operating leases	1 year 7 months 6 days		1 year 7 months 6 days
Finance leases	10 months 24 days		2 years 1 month 6 days
Weighted average discount rate
Operating leases	2.10%
Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 245,000
2022	141,000
2023	70,000
Total lease payments	456,000
Total lease payments	456,000
Less: imputed interest	(10,000)
Operating lease liability	$ 446,000	$ 172,000		$ 0

Leases - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease costs:
Finance lease amortization of right of use assets	$ 230	$ 107
Operating lease costs	578	374
Short-term lease costs	92	11
Total lease costs	$ 900	$ 492

Common Stock and Common Stock Warrant - Schedule of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Total	6,271,669	5,102,008
Options Issued And Outstanding Under The 2019 Stock Plan
Class Of Stock [Line Items]
Total	5,465,327	2,393,934
Shares Available for Issuance Under 2019 Stock Plan
Class Of Stock [Line Items]
Total	269,353	2,439,779
Shares Available for Issuance Under Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total	536,989	268,295

Common Stock and Common Stock Warrant - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2014
Equity [Abstract]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	29,543,222	26,869,413
Common stock, shares outstanding	29,543,222	26,869,413
Common stock, voting rights	Each share of common stock is entitled to one vote.
Warrants to purchase common stock			27,941
Warrants to purchase common stock, per share			$ 0.03
Warrant expiration date	2024-06
Warrant exercised month and year	2019-05

Equity Incentive Plans - Additional Information (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) Installment shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	May 07, 2019 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance \| shares	6,271,669	6,271,669	5,102,008
Total intrinsic value of options exercised	$ 6,697,000	$ 6,697,000	$ 887,000	$ 91,000
Weighted average grant date fair value of options granted \| $ / shares		$ 31.21	$ 11.11	$ 1.26
Total estimated grant date fair value of options vested		$ 10,500,000	$ 1,200,000	$ 100,000
Stock-based compensation expense related to options granted		14,470,000	2,056,000	155,000
Income tax benefits recognized		0
Unamortized employee stock-based compensation	72,700	$ 72,700
Unamortized employee stock-based compensation expected to recognized over remaining estimated vesting period		1 year 8 months 19 days
Dividend yield		0.00%
Arithmetic Average
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term		10 years
Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total intrinsic value of options exercised	0	$ 0
Weighted average grant date fair value of options granted \| $ / shares		$ 14.90
Stock-based compensation expense related to options granted		$ 203,000
Unamortized employee stock-based compensation	$ 9,854,000	$ 9,854,000
Unamortized employee stock-based compensation expected to recognized over remaining estimated vesting period		2 years 9 months
Options granted \| shares	675,000
Number of installments \| Installment	2
Number of consecutive trading days	45 days
Employees and Non-Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense related to options granted		$ 14,267,000	$ 2,056,000	$ 155,000
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum aggregate number of shares that may be issued under the plan \| shares					5,131,549
Increase in number of shares available for issuance as proportion of shares of common stock \| shares	2,146,354	2,146,354
Percentage of common stock outstanding		4.00%
Common stock reserved for issuance \| shares	269,353	269,353
2019 Plan \| Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value of options granted \| $ / shares		$ 29.60
Options granted \| shares		675,000
2019 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of shares available for issuance as proportion of shares of common stock \| shares	536,589	536,589
Percentage of common stock outstanding		1.00%
Common stock reserved for issuance \| shares					268,295
Maximum period for common stock shares reserved for future issuance		10 years

Equity Incentive Plans - Summary of Activity for Service-based Stock Options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate Intrinsic Value	$ 6,697,000	$ 887,000	$ 91,000
Service Based Stock Options \| 2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options and Unvested Shares, beginning balance	2,393,934	1,885,504	769,409
Number of Options and Unvested Shares, granted	2,798,645	932,639	1,316,342
Number of Options and Unvested Shares, exercised	(173,809)	(194,279)	(51,350)
Number of Options and Unvested Shares, Options cancelled / forfeited	(228,443)	(229,930)	(148,897)
Number of Options and Unvested Shares, ending balance	4,790,327	2,393,934	1,885,504	769,409
Number of Options and Unvested Shares, vested and expected to vest	4,790,327
Number of Options and Unvested Shares, exercisable	1,471,526
Weighted Average Exercise Price, beginning balance	$ 5.35	$ 1.57	$ 0.39
Weighted Average Exercise Price, granted	42.95	15.87	2.08
Weighted Average Exercise Price, exercised	7.38	0.51	0.46
Weighted Average Exercise Price, cancelled/forfeited	42.56	21.09	0.41
Weighted Average Exercise Price, ending balance	25.47	$ 5.35	$ 1.57	$ 0.39
Weighted Average Exercise Price, vested and expected to vest	25.47
Weighted Average Exercise Price, exercisable	$ 10.32
Weighted Average Remaining Contractual Life	8 years 8 months 8 days	8 years 7 months 13 days	9 years 25 days	8 years 10 months 20 days
Weighted Average Remaining Contractual Life, vested and expected to vest	8 years 8 months 8 days
Weighted Average Remaining Contractual Life, exercisable	7 years 7 months 20 days
Aggregate Intrinsic Value	$ 49,723,000	$ 121,593,000	$ 1,253,000	$ 1,108,000
Aggregate Intrinsic Value, vested and expected to vest	49,723,000
Aggregate Intrinsic Value, exercisable	$ 30,633,000

Equity Incentive Plans - Summary of Activity Under Performance Stock Options (Details) - $ / shares	1 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted Average Exercise Price, Options Granted		$ 31.21	$ 11.11	$ 1.26
Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Subject to Outstanding PSOs, Options granted	675,000
Weighted Average Exercise Price, Options Granted		$ 14.90
2019 Plan \| Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Subject to Outstanding PSOs, Options granted		675,000
Shares Subject to Outstanding PSOs, Ending Balance	675,000	675,000
Shares Subject to Outstanding PSOs, Outstanding	675,000	675,000
Weighted Average Exercise Price, Options Granted		$ 29.60
Weighted Average Exercise Price, Ending Balance	$ 29.60	29.60
Weighted Average Exercise Price, Outstanding	$ 29.60	$ 29.60
Weighted Average Remaining Contractual Life		9 years 11 months 8 days

Equity Incentive Plans - Summary of Employee and Non-Employee Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 14,470	$ 2,056	$ 155
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	7,441	1,378	78
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 7,029	$ 678	$ 77

Equity Incentive Plans - Summary of Weighted Average Assumptions to Calculate the Fair Value of Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Service Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	86.69%	80.19%	69.60%
Expected term (in years)	6 years 2 months 23 days	6 years 3 months	6 years 3 months
Risk-free interest rate	0.80%	1.90%	2.91%
Market Based Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	95.00%
Expected term (in years)	10 years
Risk-free interest rate	0.90%

Convertible Promissory Notes - Additional Information (Details) - USD ($)	1 Months Ended				12 Months Ended	24 Months Ended
	May 31, 2018	Jan. 31, 2018	Jun. 30, 2017	Feb. 28, 2017	Dec. 31, 2018	Jan. 31, 2019
Debt Instrument [Line Items]
Proceeds from issuance of convertible promissory note payable		$ 250,000	$ 150,000	$ 7,600,000	$ 250,000
Convertible promissory notes, Principal amount						$ 8,000,000
Change in fair value of derivative liability					(206,000)
Series B Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion of redeemable convertible preferred stock to common stock, shares	1,147,205
Issuance of stock in connection with conversion of convertible promissory notes and accrued interest	$ 800,000				$ 11,027,000
Change in fair value of derivative liability	$ 206,000
Convertible Promissory Notes
Debt Instrument [Line Items]
Convertible promissory notes interest rate						8.00%
Convertible promissory notes maturity date						Feb. 01, 2019
Minimum equity financing threshold for promissory note conversion into equity securities		$ 10,000,000
Conversion price percentage		80.00%				80.00%
Percentage of outstanding principle and accrued interest amount repayment		200.00%
Minimum gross proceeds equity financing threshold for promissory note conversion into equity securities						$ 10,000,000
Percentage of repayment premium equal to outstanding principle and accrued interest						100.00%
Debt instrument convertible conversion probability percentage in event of equity financing		90.00%	80.00%	80.00%
Debt instrument repayment probability percentage in event of merger or sale		0.00%	0.00%	0.00%
Estimated fair value of embedded derivatives liability		$ 56,250	$ 30,000	$ 1,550,000

Related Party Transactions - Additional Information (Details) - USD ($)			1 Months Ended
	Jan. 13, 2021	Feb. 10, 2020	Feb. 29, 2020	Jun. 30, 2014
Related Party Transaction [Line Items]
Percentage of royalties payment to stockholders in amount of gross revenues				3.00%
LifeSci Advisors, LLC \| Consulting Services \| Subsequent Event
Related Party Transaction [Line Items]
Payable under agreement	$ 180,000
Term of agreement	1 year
Private Placement
Related Party Transaction [Line Items]
Agreement date			Feb. 10, 2020
Number of shares issued and sold			2,500,000
Proceeds from issuance of common stock			$ 125,000,000
Offering price per share			$ 50.00
Private Placement \| David A. Lamond
Related Party Transaction [Line Items]
Agreement date		Feb. 10, 2020
Number of shares issued and sold		30,000
Proceeds from issuance of common stock		$ 1,500,000
Offering price per share		$ 50.00
Maximum
Related Party Transaction [Line Items]
Payment of royalties to stockholders				$ 1,050,000

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Provision (benefit) for income taxes	$ 0	$ 0	$ 0
Deferred tax asset	0	0
Valuation allowances increased	18,500,000	8,500,000	3,000,000
Liability related to uncertain tax positions	0
Interest or penalties accrued	0	$ 0	$ 0
Earliest Tax Year \| U.S. Federal
Income Taxes [Line Items]
Open tax year		2013
Earliest Tax Year \| California State Tax Examinations
Income Taxes [Line Items]
Open tax year		2013
Latest Tax Year \| U.S. Federal
Income Taxes [Line Items]
Open tax year		2020
Latest Tax Year \| California State Tax Examinations
Income Taxes [Line Items]
Open tax year		2020
U.S. Federal
Income Taxes [Line Items]
Operating loss carryforwards	128,200,000
Operating loss carryforwards, not subject to expiration	112,300,000
Operating loss carryforwards, subject to expiration	$ 15,900,000
Operating loss carryforwards begin to expire	2034
Tax credit carryforwards	$ 4,900,000
Tax credits carryforwards begin to expire	2036
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 4,900,000
Operating loss carryforwards begin to expire	2034
Tax credit carryforwards	$ 1,100,000
Internal Revenue Code
Income Taxes [Line Items]
Period of cumulative change in ownership	3 years
Minimum \| Internal Revenue Code
Income Taxes [Line Items]
Cumulative change in ownership percentage	50.00%

Income Taxes - Schedule of Provision for Income Taxes Differs From the Amount Expected by Applying the Federal Statutory Rate to Loss Before Taxes (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	21.00%	21.00%
State income taxes	0.55%	(1.12%)	6.24%
Income tax credits	2.14%	3.67%
Non-deductible expenses and others	0.44%	(0.38%)	(1.02%)
Non-deductible expenses related to the convertible promissory notes			(1.96%)
Change in valuation allowance	(24.13%)	(23.17%)	(24.26%)

Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred tax asset:
Federal and State net operating loss carryforwards	$ 28,072,000	$ 14,219,000
Stock based compensation	2,633,000	238,000
Other accruals and deferred expense	566,000	185,000
Tax credits	3,928,000	1,867,000
Gross deferred tax asset	35,199,000	16,509,000
Valuation allowance	(35,034,000)	(16,489,000)
Total deferred tax assets	165,000	20,000
Deferred tax liabilities:
Property and equipment	(14,000)	(20,000)
Capitalized leases	(151,000)
Gross deferred tax liabilities	(165,000)	(20,000)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Beginning balance	$ 1,059	$ 356	$ 171
Additions for tax positions taken in a prior year		168
Additions for tax positions taken in a current year	917	535	185
Ending balance	$ 1,976	$ 1,059	$ 356

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss	$ (76,849)	$ (36,980)	$ (12,476)
Denominator
Weighted average common shares outstanding	29,176,232	19,031,940	3,362,192
Net loss per share - basic and diluted	$ (2.63)	$ (1.94)	$ (3.71)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Net Loss Per Share - Schedule of Outstanding Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	5,465,327	2,393,934	20,074,472
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount			9,008,919
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount			9,152,108
Stock Options Issued and Outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	4,790,327	2,393,934	1,885,504
Performance Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	675,000
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount			27,941

Employee Benefit Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Percentage of employee contribution of their annual compensation	100.00%
Contributions	$ 0	$ 0	$ 0
Defined contribution plan name	401(k)
Defined Contribution Plan, Plan Name [Extensible List]	us-gaap:QualifiedPlanMember