Atea Pharmaceuticals (AVIR) 10-K 30 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Mar. 29, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	ATEA PHARMACEUTICALS, INC.
Trading Symbol	AVIR
Entity Central Index Key	0001593899
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		82,736,937
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Current Reporting Status	Yes
Entity Tax Identification Number	46-0574869
Entity File Number	001-39661
Entity Address, Address Line One	125 Summer Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02110
City Area Code	857
Local Phone Number	284-8891
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 0
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2021 Annual Meeting of Stockholders, which the registrant intends to file with the Securities and Exchange Commission within 120 days after the end of the registrant’s fiscal year ended December 31, 2020, are incorporated by reference into Part III of this Annual Report on Form 10-K .

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 850,117	$ 21,661
Unbilled other receivable	5,815
Prepaid expenses and other current assets	7,545	249
Total current assets	863,477	21,910
Property and equipment, net	48	41
Other assets	107	122
Total Assets	863,632	22,073
Current liabilities
Accounts payable	60	548
Accrued expenses and other current liabilities	14,368	1,887
Deferred revenue	301,367
Total current liabilities	315,795	2,435
Other liabilities	36	95
Total liabilities	315,831	2,530
Commitments and contingencies (see Note 7)
Convertible preferred stock, $0.001 par value; 0 and 33,645,447 shares authorized, issued and outstanding as of December 31, 2020 and 2019		69,114
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value per share; 10,000,000 and 0 shares authorized; no shares issued and outstanding as of December 31, 2020 and 2019
Common stock, $0.001 par value; 300,000,000 and 53,070,161 shares authorized as of December 31, 2020 and 2019; 82,436,937 and 10,091,100 shares issued and outstanding as of December 31, 2020 and 2019	82	10
Additional paid-in capital	612,879	4,632
Accumulated deficit	(65,160)	(54,213)
Total stockholders’ equity (deficit)	547,801	(49,571)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 863,632	$ 22,073

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	33,645,447
Convertible preferred stock, shares issued	0	33,645,447
Convertible preferred stock, shares outstanding	0	33,645,447
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	53,070,161
Common stock, shares issued	82,436,937	10,091,100
Common stock, shares outstanding	82,436,937	10,091,100

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Collaboration revenue	$ 48,633
Operating expenses
Research and development	38,023	$ 10,170	$ 6,675
General and administrative	21,640	4,438	2,802
Total operating expenses	59,663	14,608	9,477
Loss from operations	(11,030)	(14,608)	(9,477)
Interest income and other, net	83	574	413
Net and comprehensive loss	$ (10,947)	$ (14,034)	$ (9,064)
Net loss per share attributable to common stockholders – basic and diluted	$ (0.51)	$ (1.39)	$ (0.90)
Weighted-average number of common shares used in computing net loss per share attributable to common stockholders– basic and diluted	21,592,441	10,091,100	10,039,392

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Series D Convertible Preferred Stock	Series D-1 Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2017	$ (27,511)				$ 10	$ 3,594	$ (31,115)
Balance, shares at Dec. 31, 2017		27,592,830
Balance at Dec. 31, 2017		$ 41,755
Balance, shares at Dec. 31, 2017					9,987,767
Issuance of convertible preferred stock, net of issuance costs		$ 27,359
Issuance of convertible preferred stock, net of issuance costs, shares		6,052,617
Stock-based compensation in connection with vesting of restricted stock, shares					103,333
Stock-based compensation expense	414					414
Net loss	(9,064)						(9,064)
Balance at Dec. 31, 2018	(36,161)				$ 10	4,008	(40,179)
Balance, shares at Dec. 31, 2018		33,645,447
Balance at Dec. 31, 2018		$ 69,114
Balance, shares at Dec. 31, 2018					10,091,100
Stock-based compensation expense	624					624
Net loss	(14,034)						(14,034)
Balance at Dec. 31, 2019	$ (49,571)				$ 10	4,632	(54,213)
Balance, shares at Dec. 31, 2019	33,645,447	33,645,447
Balance at Dec. 31, 2019	$ 69,114	$ 69,114
Balance, shares at Dec. 31, 2019					10,091,100
Issuance of convertible preferred stock, net of issuance costs			$ 106,631	$ 107,485
Issuance of convertible preferred stock, net of issuance costs, shares			15,313,382	8,973,261
Issuance of common stock for exercise of stock options	$ 27					27
Issuance of common stock for exercise of stock options, shares	18,747				18,747
Stock-based compensation in connection with vesting of restricted stock	$ 657					657
Stock-based compensation in connection with vesting of restricted stock, shares					20,000
Initial public offering, net of issuance costs of $3,245	317,605				$ 14	317,591
Initial public offering, net of issuance costs of $3,245, shares					14,375,000
Conversion of preferred stock into common stock	283,230				$ 58	283,172
Conversion of preferred stock into common stock, shares		(57,932,090)
Conversion of preferred stock into common stock	283,230	$ (283,230)
Conversion of preferred stock into common stock, shares					57,932,090
Stock-based compensation expense	6,800					6,800
Net loss	(10,947)						(10,947)
Balance at Dec. 31, 2020	$ 547,801				$ 82	$ 612,879	$ (65,160)
Balance, shares at Dec. 31, 2020	0
Balance, shares at Dec. 31, 2020					82,436,937

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Initial Public Offering
Stock issuance costs	$ 3,245
Convertible Preferred Stock
Stock issuance costs		$ 241
Series D Convertible Preferred Stock
Stock issuance costs	869
Series D-1 Convertible Preferred Stock
Stock issuance costs	$ 15

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (10,947)	$ (14,034)	$ (9,064)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Stock-based compensation expense	7,457	624	414
Depreciation and amortization expense	19	17	17
Changes in operating assets and liabilities
Unbilled accounts receivable	(5,815)
Prepaid expenses and other current assets	(7,296)	(43)	86
Accounts payable	(488)	157	(90)
Accrued expenses and other liabilities	12,437	450	729
Deferred revenue	301,367
Net cash provided by (used in) operating activities	296,734	(12,829)	(7,908)
Cash flows from investing activities
Additions to property and equipment	(26)	(2)	(12)
Net cash used in investing activities	(26)	(2)	(12)
Cash flows from financing activities
Net proceeds from issuance of convertible preferred stock	214,116		27,359
Proceeds from issuance of common stock	27		124
Net proceeds from initial public offering of common stock	317,605
Net cash provided by financing activities	531,748		27,483
Net increase in cash, cash equivalents and restricted cash	828,456	(12,831)	19,563
Cash, cash equivalents and restricted cash at the beginning of period	21,768	34,599	15,036
Cash, cash equivalents and restricted cash at the end of period	850,224	21,768	34,599
Cash, cash equivalents and restricted cash at the end of period
Cash and cash equivalents	850,117	21,661	34,492
Restricted cash	107	107	107
Cash, cash equivalents and restricted cash at the end of period	850,224	$ 21,768	$ 34,599
Supplemental disclosure of non-cash financing activities
Conversion of preferred stock to common stock upon closing of initial public offering	$ 283,230

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Atea Pharmaceuticals, Inc., together with its subsidiary Atea Pharmaceuticals Securities Corporation, is referred to on a consolidated basis as “the Company”. The Company is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing antiviral therapeutics to improve the lives of patients suffering from life-threatening viral infections. In October 2020, the Company entered into a license agreement, (“the License Agreement”) with F. Hoffmann-La Roche Ltd and Genentech, Inc. (collectively “Roche”), granting Roche an exclusive license to develop and commercialize certain of the Company’s compounds outside of the United States. Atea is responsible for completing certain ongoing clinical and non-clinical and manufacturing activities and at its own expense. As part of the consideration, Roche agreed to pay the Company an upfront payment of $350,000 (the “Roche Upfront Payment”), which was received in November 2020. On November 3, 2020, the Company completed an initial public offering of its common stock (the “IPO”). In connection with the IPO, the Company issued 14,375,000 shares of its common stock at $24.00 per share for net proceeds of $317,605 after deducting underwriting discounts and commissions and offering expenses. Upon closing of the IPO, all outstanding shares of the Company’s convertible preferred stock converted into 57,932,090 shares of common stock. The Company is subject to risks and uncertainties common to clinical-stage biopharmaceutical companies. These risks include, but are not limited to, potential failure of preclinical and clinical studies, uncertainties associated with research and development activities generally, competition from technical innovations of others, dependence upon key personnel, compliance with governmental regulations, the need to obtain marketing approval for any product candidate that the Company may discover and develop, the need to gain broad acceptance among patients, payers and health care providers to successfully commercialize any product for which marketing approval is obtained and the need to secure and maintain adequate intellectual property protection for the Company’s proprietary technology and products. Further, the Company is currently dependent on third-party service providers for much of its preclinical research, clinical development and manufacturing activities. Product candidates currently under development will require significant amounts of additional capital, additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. Even if the Company is able to generate revenues from the sale of its product candidates, if approved, it may not become profitable. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations. The Company is also subject to risks associated with the COVID-19 global pandemic, including actual and potential delays associated with certain of its ongoing and anticipated trials, and potential negative impacts on the Company’s business operations and its ability to raise additional capital to finance its operations. Since its inception, the Company has incurred recurring operating losses. As of December 31, 2020, the Company had an accumulated deficit of $65,160. The Company expects to continue to generate operating losses for the foreseeable future. The Company believes that its cash and cash equivalents of $850,117 as of December 31, 2020 will be sufficient to fund its operations as currently planned through at least 2023. The Company may seek additional capital through one or more of a combination of financing through the sale of additional equity securities, debt financing, or funding in connection with any additional collaborative relationships it may enter into or other arrangements. There can be no assurance that the Company will be able to obtain such additional funding, on terms acceptable to the Company, on a timely basis or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s existing shareholders.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, or GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and in these accompanying notes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors and assumptions that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, which include but are not limited to estimates of revenue, accrued research and development expenses, and the valuation of common stock in connection with the issuance of stock-based awards prior to the completion of the IPO. Changes in estimates are recorded in the period in which they become known. Principles of Consolidation The consolidated financial statements include the accounts of Atea Pharmaceuticals, Inc. and its wholly- owned subsidiary, Atea Pharmaceuticals Securities Corporation. All intercompany amounts have been eliminated in consolidation. Revenue Recognition As of December 31, 2020, all of the Company’s revenue to date had been collaboration revenue generated from its license agreement with Roche. The Company analyzes its collaboration arrangements to assess whether they are within the scope of Accounting Standards Codification ASC Topic 808, Collaborative Arrangements (“ Research and Development Revenue from Contracts with Customers To determine the appropriate amount of revenue to be recognized for arrangements that the Company determines are within the scope of ASC 606, it performs the following steps: (i) identify the contract(s) with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) each performance obligation is satisfied. ASC 606 requires significant judgment and estimates and results in changes to, but not limited to: (i) the determination of the transaction price, including estimates of variable consideration, (ii) the allocation of the transaction price, including the determination of estimated selling price, and (iii) the pattern of recognition, including the application of proportional performance as a measure of progress on service-related promises and application of point-in-time recognition for supply-related promises. The transaction price is generally comprised of an upfront payment due at contract inception and variable consideration in the form of payments for the Company’s services and materials and milestone payments due upon the achievement of specified events. Other payments the Company could be entitled to include tiered royalties earned when customers recognize net sales of licensed products. The Company considers the existence of any significant financing component within its arrangements and has determined that a significant financing component does not exist in its arrangements as substantive business purposes exist to support the payment structure other than to provide a significant benefit of financing. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes either the expected value method or the most likely amount method to estimate the amount of variable consideration, depending on which method is expected to better predict the amount of consideration to which the Company will be entitled. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. With respect to arrangements that include payments for a development or regulatory milestone payment, the Company evaluates whether the associated event is considered probable of achievement and estimate the amount to be included in the transaction price using the most likely amount method. Milestone payments that are not within the Company’s control or the licensee, such as those dependent upon receipt of regulatory approval, are not considered to be probable of achievement until the triggering event occurs. At the end of each reporting period, the Company re-evaluates the probability of achievement of each milestone and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments based upon the achievement of a certain level of product sales, wherein the license is deemed to be the sole or predominant item to which the payments relate, the Company recognizes revenue upon the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). Consideration that would be received for optional goods and/or services is excluded from the transaction price at contract inception. The Company generally allocates the transaction price to each performance obligation based on a relative standalone selling price basis. The Company develops assumptions that require judgment to determine the standalone selling price for each performance obligation in consideration of applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated research and development costs. However, in certain instances, the Company allocates variable consideration entirely to one or more performance obligation if the terms of the variable consideration relate to the satisfaction of the respective performance obligation and the amount allocated is consistent with the amount the Company would expect to receive for the satisfaction of the respective performance obligation. The Company recognizes revenue based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good or service to the customer. For performance obligations that are satisfied at a point in time, the Company recognizes revenue when control of the goods and/or services is transferred to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company generally uses input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. With respect to arrangements containing a license to its intellectual property that is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from amounts allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. Contract costs The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. The Company has elected the practical expedient in ASC 340, Other Assets and Deferred Costs Cash and Cash Equivalents The Company considers all highly-liquid investments purchased with maturities of 90 days or less at acquisition to be cash equivalents. Cash and cash equivalents include bank demand deposits and money market funds that invest in U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value. Concentrations of Credit Risk and Significant Suppliers Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains its cash and cash equivalents with a financial institution that management believes is creditworthy. The Company’s investment policy includes guidelines on the quality of the financial institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs. Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Observable inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determination of fair value of the assets or liabilities. Cash, cash equivalents and restricted cash are Level 1 assets which are comprised of funds held in checking and money market accounts. Cash, cash equivalents and restricted cash were recorded at fair value as disclosed in Note 4. The carrying amounts of accounts payable, accrued expenses and unbilled other receivables approximate their fair values due to their short-term maturities. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the asset. The Company estimates the useful life of its assets as follows: Asset Estimated useful life Laboratory equipment Five years Office furniture and fixtures Five years Computer hardware Two years Leasehold improvements Shorter of useful life or remaining lease term Maintenance and repairs that do not improve or extend the life of the respective asset are expensed to operations as incurred. Upon disposal of an asset, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the consolidated statements of operations. Other Assets Other assets consists primarily of bank deposits of $107, classified as restricted cash, to collateralize a letter of credit. Impairment of Long-lived Assets The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book value of the assets to the estimated undiscounted future net cash flows that the asset is expected to generate. If the estimated undiscounted future net cash flows are less than the book value, the asset is impaired, and the impairment loss to be recognized in income is measured as the amount by which the book value of the asset exceeds its fair value, which is measured based on the estimated discounted future net cash flows that the asset is expected to generate. No impairment losses were recorded during the years ended December 31, 2020, 2019 and 2018. Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist principally of costs associated with outsourced research and development activities, including preclinical and clinical development, manufacturing and research conducted by contract research organizations and academic institutions, employee compensation, including stock-based compensation and consulting expenses together with related expenses, professional fees and facility and overhead costs. Facility and overhead costs primarily include the allocation of rent, utility and office-related expenses attributable to research and development personnel. In circumstances where amounts have been paid in advance or in excess of costs incurred, the Company records a prepaid expense, which is expensed as services are performed or goods are delivered. The Company has entered into various research and development contracts with third parties. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase of completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Patent Costs Costs to secure and maintain the Company’s patents are expensed as incurred and are classified as general and administrative expenses in the Company’s consolidated statements of operations. Stock-based Compensation Stock-based compensation expense is classified in the consolidated statement of operations in the same manner in which the award recipient’s payroll costs or service payments are classified. Stock-based awards granted to employees and non-employees are measured based on the estimated fair value of the awards using the Black-Scholes option pricing model (“Black-Scholes”). Stock-based compensation expense with respect to awards with service conditions is recognized using the straight-line method over the service period. Stock-based compensation with respect to awards with performance conditions is recognized when satisfaction of the performance conditions is probable. Stock-based compensation is based on awards ultimately expected to vest and, as such, it is reduced by forfeitures. The Company accounts for forfeitures as they occur. Black-Scholes requires the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include: Fair value of common stock — Through October 29, 2020, because there was no public market for the Company’s common stock, the fair value of the Company’s common stock underlying stock-based awards was estimated on each grant date by the board of directors. In the absence of a public trading market for the Company’s common stock prior to its IPO, on each grant date, the Company developed an estimate of the fair value of its common stock based on valuations from an independent third-party valuation firm using information known to the Company on the date of grant, a review of any recent events and their potential impact on the estimated fair value per share of the common stock. The third-party valuations of the Company’s common stock were determined in accordance with the guidelines outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation, or the Practice Aid. The assumptions used to determine the estimated fair value of the Company’s common stock are based on numerous objective and subjective factors, combined with management judgment, including: • external market conditions affecting the pharmaceutical and biotechnology industry and trends within the industry; • the Company’s stage of development and business strategy; • the rights, preferences and privileges of the Company’s redeemable convertible preferred stock relative to those of its common stock; • the prices at which the Company sold shares of its redeemable convertible preferred stock; • the Company’s financial condition and operating results, including our levels of available capital resources; • the progress of the Company’s research and development efforts; • equity market conditions affecting comparable public companies; and • general U.S. market conditions and the lack of marketability of the Company’s common stock. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In accordance with the Practice Aid, the Company considered the following methods: • Option Pricing Method . Under the option pricing method (“OPM”), shares are valued by creating a series of call options with exercise prices based on the liquidation preferences and conversion terms of each equity class. The estimated fair values of the preferred and common stock are inferred by analyzing these options. • Probability-Weighted Expected Return Method. The probability-weighted expected return method (“PWERM”), is a scenario-based analysis that estimates value per share based on the probability-weighted present value of expected future investment returns, considering each of the possible outcomes available to us, as well as the economic and control rights of each share class. Based on the Company’s early stage of development and other relevant factors, the Company determined that OPM method as well as a hybrid approach of the OPM and the PWERM methods were the most appropriate methods for allocating its enterprise value to determine the estimated fair value of its common stock. In determining the estimated fair value of the Company’s common stock, its board of directors also considered the fact that its stockholders could not freely trade its common stock in the public markets. Accordingly, the Company applied discounts to reflect the lack of marketability of its common stock based on the weighted-average expected time to liquidity. The estimated fair value of our common stock at each grant date reflected a non-marketability discount partially based on the anticipated likelihood and timing of a future liquidity event. Upon the completion of the Company’s initial public offering, the fair value of its common stock is based on the daily closing quoted market price of its common stock. Risk-free interest rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of a stock-based award. Expected term —The expected term represents the period that stock-based awards are expected to be outstanding. Given the Company’s lack of specific history, the expected term for option grants is determined using the simplified method. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the stock-based awards. Expected volatility —Since the Company was privately held through October 29, 2020 and did not have any trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock-based awards. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Expected dividend yield —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. The Company also accounts for any modifications to share based payments in accordance with ASC 718. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax base. Deferred tax assets, which relate primarily to the carrying amount of the Company’s net operating loss carryforwards, are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established to reduce deferred tax assets where, based upon the available evidence, the Company concludes that it is more-likely-than-not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income. Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more-likely-than-not to be sustained on examination by a taxing authority. Interest and penalties related to uncertain tax positions are recognized in the provision of income taxes. Comprehensive Loss Comprehensive income (loss) includes net income (loss) as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with equity holders. The Company did not have any items of comprehensive income or loss other than net loss for the years ended December 31, 2020, 2019 and 2018. Net Loss Per Share Attributable to Common Stockholders The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. The Company considers its convertible preferred stock to be participating securities as, in the event a dividend is paid on common stock, the holders of convertible preferred stock would be entitled to receive dividends on a basis consistent with the common stockholders. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible preferred stock as the holders of the convertible preferred stock do not have a contractual obligation to share in losses. Since inception, the Company has incurred recurring operating losses and, as such, under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock. Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that the participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss, as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed by using the weighted-average number of shares of common stock outstanding. Due to net losses for the years ended December 31, 2020, 2019 and 2018, basic and diluted net loss per share attributable to common stockholders were the same, as the effect of all potentially dilutive securities would have been anti-dilutive. Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker (the “CODM”), in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its chief executive officer, who manages and allocates resources to the operations on a total company basis. Accordingly, there is a single operating segment and one reportable segment. Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases The Company plans to use the modified retrospective method of adoption and to elect the available practical expedients. The Company expects that the adoption of the new leasing standard will result in the recognition of a material right to use asset and lease liability in the consolidated balance sheets and does not expect it to have a material impact to its results of operations or statements of cash flows. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”) . Recently Adopted Accounting Pronouncements In November 2018, the FASB , Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606.

Collaboration Revenue

Collaboration Revenue	12 Months Ended
	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Collaboration Revenue	3. Collaboration Revenue Background In October 2020, the Company entered into the Roche License Agreement, granting Roche an exclusive license to develop and commercialize certain of the Company’s compounds outside of the United States. Atea is responsible for completing certain ongoing clinical and non-clinical and manufacturing activities and at its own expense. These obligations are referred to as the Atea Ongoing Studies and the Atea Manufacturing Obligations. The parties will work collaboratively on a global development plan intended to support regulatory approvals and will share joint development costs equally. The agreement provided for a nonrefundable upfront payment of $350,000 which the Company received in November 2020. In addition, the Roche License Agreement further provides that Roche is obligated to pay the Company up to $330,000 in the aggregate upon the achievement of certain development and regulatory milestone events; up to $320,000 in the aggregate upon the achievement of certain sales based milestone events; and tiered royalties based on annual net sales of the products covered by the Roche License Agreement, ranging between low double-digits and mid-twenties, subject to certain adjustments and limitations. Roche has the right to terminate the Roche License Agreement for convenience pursuant to the terms of the agreement. In addition, the Roche License Agreement contains a provides for a co-promotion agreement for the United States at the Company’s election. Accounting Analysis The Company concluded that the License Agreement is under the scope of ASC 808 as both parties will actively participate in a joint operating activity and are exposed to significant risks and rewards that depend on the activity’s commercial success. ASC 808 provides that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaborative arrangement participant is a customer in the context of a unit of account. In those situations, all of the guidance in ASC 606 should be applied, including recognition, measurement, presentation, and disclosure requirements related to such unit of account. The unit-of-account guidance in ASC 808, which aligns with the guidance in ASC 606 (that is, a distinct good or service) is used when an entity is assessing whether the collaborative arrangement or a part of the arrangement is within the scope of ASC 606. Based on the Company’s analysis, it concluded that the delivery of the license to Roche, the performance of the Atea Ongoing Studies and the Atea Manufacturing Obligations should be accounted for under ASC 606. The Company’s efforts under the Global Development Plan, which include certain manufacturing obligations in the initial year of the contract, will be accounted for under ASC 808. The Company concluded that the provision of the license to Roche, the performance of the Atea Ongoing Studies and the Atea Manufacturing Obligations should be combined as one performance obligation as Roche cannot receive the benefit of each promise without the other promises. Specifically, Roche is dependent on the Company’s expertise and ability to complete the Atea Ongoing Studies and the Atea Manufacturing Obligations, which cannot be performed by other third parties, in order to exploit the value from the license. The transaction price consists of the $350,000 upfront payment. The Company concluded that all other forms of variable consideration, including future development and regulatory milestones should be constrained at contract inception. As part of this conclusion, the Company assessed the stage of development and risk associated with remaining development required to achieve each milestone, including whether the achievement of certain milestones was outside the control of the Company. Sales based milestone payments and royalty payments qualify for the sales based royalty exception and will be recognized when the underlying sale transaction have occurred. The transaction price will be recognized as collaboration revenue over the period in which the Company performs the Atea Ongoing Studies and the Atea Manufacturing Activities. The Company concluded that an inputs method based on costs incurred compared to total estimated costs-to-complete approach most faithfully depicts the Company’s progress towards completion. The Company concluded that its efforts to complete the Global Development Plan will be accounted for under ASC 808. The Company will account for expenses incurred and reimbursements made or received from Roche pursuant to ASC 730, Research and Development The Company incurred approximately $7,000 of capitalizable costs to obtain the contact. The Company will utilize the practical expedient in ASC 340 and recognize such costs immediately as the Company expected to complete its performance obligations under the Roche License Agreement in less than 12 months. The Company classifies all revenues recognized under the Roche License Agreement as collaboration revenues within the accompanying consolidated statements of operations and comprehensive loss. For the year ended December 31, 2020, the Company recognized collaboration revenue of $48,633 related to the combined performance obligation. As of December 31, 2020, the Company recorded Deferred Revenue of $301,367 related to the Roche License Agreement. Deferred Revenue is classified in current liabilities in the accompanying balance sheet as of December 31, 2020 as the performance obligation is expected to be completed within twelve months (or one year) from the inception of the contract. For the year ended December 31, 2020, costs reimbursable by Roche and reflected as a reduction to operating expenses were $7,901, of which $5,815 had not been reimbursed by Roche as of December 31, 2020 and was recorded as Unbilled other receivable in current assets in the accompanying consolidated balance sheet. The Company also recorded research and development expense of $2,086 related to its share of costs incurred by Roche.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of December 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 846,701 $ — $ — $ 846,701 Total cash equivalents $ 846,701 $ — $ — $ 846,701 Fair Value Measurements as of December 31, 2019 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 21,038 $ — $ — $ 21,038 Total cash equivalents $ 21,038 $ — $ — $ 21,038 The Company’s assets with fair value categorized as Level 1 within the fair value hierarchy include money market accounts which invest in money market funds are publicly traded mutual funds and are presented as cash equivalents on the consolidated balance sheets as of December 31, 2020 and 2019. There were no transfers among Level 1, Level 2 or Level 3 categories in the years ended December 31, 2020, 2019 and 2018.

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, net	5. Property and Equipment, net Property and equipment, net, consist of the following: December 31, 2020 2019 Laboratory equipment $ 5 $ 5 Office furniture and fixtures 13 13 Computer hardware 37 11 Leasehold improvements 125 125 Total property and equipment, at cost 180 154 Less: accumulated depreciation and amortization (132 ) (113 ) Property and equipment, net $ 48 $ 41 Depreciation and amortization expense was $19, $17 and $17 for the years ended December 31, 2020, 2019 and 2018, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: December 31, 2020 2019 Research and development, including manufacturing and clinical expenditures $ 10,546 $ 1,326 License fees (Note 7) — 200 Professional fees and other 1,079 361 Payroll and payroll related 2,743 — Total accrued expenses and other current liabilities $ 14,368 $ 1,887

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Operating Lease Agreements The Company leases an office facility under a non-cancelable operating lease that expires July 2022. The office lease includes commitments obligating the Company to pay a pro rata share of certain building operating costs and annual rent escalations which will result in higher lease payments in future years. Rent expense is recognized on a straight-line basis over the term of the lease with the difference between expense and the payments recorded as deferred rent, which is included in accrued expenses and other current liabilities and other liabilities in the consolidated balance sheets. As of December 31, 2020, future minimum payments for operating leases are as follows: 2021 $ 340 2022 200 Total future minimum lease payments $ 540 Rent expense recognized under all operating leases was $303, $305 and $316 for the years ended December 31, 2020, 2019 and 2018, respectively. The Company is required to maintain a letter of credit for the duration of the office lease. The Company maintains bank deposits of $107 to collateralize the letter of credit which are classified as restricted cash and a long-term asset in the consolidated balance sheets as of December 31, 2020 and 2019. The Company has an agreement with a consultant that requires payment of a success fee calculated as a percentage of certain product sales, subject to a cumulative maximum payout of $5.0 million. This success payment is contingent upon the occurrence of future events and the timing and likelihood of such payment is neither probable nor estimable. Indemnification The Company enters into certain types of contracts that contingently requires the Company to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company’s bylaws, under which the Company must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers and consultants for liabilities arising out of their relationship, and (iii) procurement, service or license agreements under which the Company may be required to indemnify vendors, service providers or licensees for certain claims, including claims that may be brought against them arising from the Company’s acts or omissions with respect to the Company’s products, technology, intellectual property or services. From time to time, the Company may receive indemnification claims under these contracts in the normal course of business. In the event that one or more of these matters were to result in a claim against the Company, an adverse outcome, including a judgment or settlement, may cause a material adverse effect on the Company’s future business, operating results or financial condition. It is not possible to determine the maximum potential amount potentially payable under these contracts since the Company has no history of prior indemnification claims and the unique facts and circumstances involved in each particular claim will be determinative.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Convertible Preferred Stock	8. Convertible Preferred Stock As of December 31, 2019, the Company had 33,645,447 shares of convertible preferred stock (“Convertible Preferred Stock), authorized, issued and outstanding, of which 20,000,000 shares were designated as Series A convertible preferred stock (“Series A Preferred”); 7,592,830 shares were designated as Series B convertible preferred stock (“Series B Preferred”); and 6,052,617 shares were designated as Series C convertible preferred stock (“Series C Preferred”). The Company’s Series A Preferred, Series B Preferred and Series C Preferred were issued at $1.00, $3.03 and $4.56 per share, respectively. In May 2020, the Company authorized 15,313,382 shares of Series D convertible preferred stock (“Series D Preferred”) and 8,973,261 shares of Series D-1 convertible preferred stock (“Series D-1 Preferred”). In May 2020 the Company entered into a stock purchase agreement with certain investors and issued 15,313,382 shares of Series D Preferred for net proceeds of $106,631. In October 2020, the Company issued 8,973,261 shares of Series D-1 Preferred at a purchase price of $11.98 per share for aggregate net proceeds of $107,485. In connection with the Company’s IPO, all shares of its convertible preferred stock converted into 57,932,090 shares of common stock. As of December 31, 2020 the Company has 10,000,000 shares of preferred stock authorized. No shares of preferred stock have been issued.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Common Stock	9. Common Stock At December 31, 2020, the authorized capital of the Company included 300,000,000 shares of common stock, of which 82,436,937 shares of common stock were issued and outstanding. On all matters to be voted upon by the holders of common stock, holders of common stock are entitled to one vote per share. The holders of common stock are entitled to receive dividends, when declared by the board, and to share ratably in the Company’s assets legally available for distribution to the holders of the Company’s stock in the event of liquidation. The holders of common stock have no preemptive, redemption or conversion rights. The Company had the following reserved shares of common stock: December 31, 2020 December 31, 2019 Series A Preferred — 20,000,000 Series B Preferred — 7,592,830 Series C Preferred — 6,052,617 Outstanding options 7,917,783 3,911,633 Options available for future grant 7,059,000 450,567 Shares reserved under ESPP 1,187,000 — 16,163,783 38,007,647

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	10. Stock-based Compensation In October 2020, the Company’s shareholders approved the Company’s 2020 Incentive Award Plan (the “2020 Plan”), which became effective in connection with the Company’s initial public offering on October 29, 2020. The 2020 Plan provides for the issuance of up to 7,924,000 shares of common stock and for grant of incentive stock options or other incentive awards to employees, members of the board of directors and consultants of the Company. The number of shares of common stock that may be issued under 2020 Plan is also subject to increase on the first day of each calendar year equal to the lesser of i) 5% of the aggregate number of shares of common stock outstanding on the final day of the immediately preceding calendar year or ii) such smaller number of shares as is determined by the board of directors. In January 2021, the shares available under the plan were increased by 4,130,847 shares. The 2020 Plan replaced and is the successor of 2013 Equity Incentive Plan, as amended (the “2013 Plan”), which provided for the grant of incentive stock options, non-qualified stock options, restricted common stock awards and other awards for up to 7,807,200 shares of common stock to employees, officers, directors and consultants of the Company. Upon the closing of the Company’s initial public offering the 2013 Plan was terminated and no further awards will be made under the 2013 Plan. Any cancellation of outstanding awards at the time of the IPO under the 2013 Plan will be made available for grant under 2020 Plan. As of December 31, 2020 there were 7,059,000 shares of common stock remaining available for future issuance under the 2020 Plan. Restricted Common Stock Restricted stock awards generally include vesting and risk of forfeiture provisions that lapse upon satisfaction of performance conditions or over time periods commencing on the grant date and concluding on the third or fourth anniversary of the grant date. As of December 31, 2020, there were no unvested shares of restricted stock. As of January 1, 2020, the Company had issued 200,000 shares of restricted stock to a consultant in connection with a business development agreement that were subject to vesting provisions. In December 2020, the Company and the consultant agreed to terminate the consulting agreement. In connection with the termination, the Company agreed to vest 20,000 shares of restricted stock. The Company recorded compensation expense of $657 in connection with the vesting. The remaining 180,000 shares of restricted stock have been forfeited. Employee Stock Purchase Plan In October 2020, the Company’s shareholders approved the 2020 Employee Stock Purchase Plan (the “ESPP”), which became effective in connection with the Company’s initial public offering on October 29, 2020. A total of 1,187,000 shares of common stock are reserved for issuance under this plan. As of December 31, 2020 the Company had not commenced any offering under the ESPP and no shares have been issued. Stock Options The following summarizes stock option activity: Number of Shares Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2020 3,911,633 $ 1.50 8.5 $ 3,915 Granted 4,613,861 $ 14.93 Exercised (18,747 ) $ 1.43 Cancelled (588,964 ) $ 6.83 Outstanding at December 31, 2020 7,917,783 $ 6.68 8.6 $ 277,894 Options exercisable at December 31, 2020 3,246,548 $ 1.88 7.4 $ 129,531 Vested or expected to vest at December 31, 2020 7,917,783 $ 6.68 8.6 $ 277,894 The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock for those options that had exercise prices lower than the fair value of the Company’s common stock. Option grants generally vest over a service period of three or four years and have a contractual term of ten years. As of December 31, 2020, total unrecognized compensation expense related to stock option awards was $33,240, which amount is being recognized over a remaining weighted average period of 3.7 years. The weighted average grant date fair value per option granted during the years ended December 31, 2020, 2019 and 2018 was $14.93, $1.19 and $0.77, respectively. The fair value of each award was estimated using Black-Scholes based on the following assumptions: For the Year Ended December 31, 2020 2019 2018 Risk-free interest rate 0.31 - 0.56% 1.61 - 2.02% 2.45 - 2.89% Expected term 6.25 years 5.52 - 10.0 years 5.52 - 9.96 years Expected volatility 80.0% - 91.7% 49.2% - 78.0% 49.2 % Expected dividend yield 0 % 0 % 0 % Stock-based Compensation Expense Stock-based compensation expense is classified as follows: For the Year Ended December 31, 2020 2019 2018 Research and development expense $ 3,565 $ 255 $ 192 General and administrative 3,892 369 222 Total stock-based compensation expense $ 7,457 $ 624 $ 414 The components of stock-based compensation expense were: For the Year Ended December 31, 2020 2019 2018 Restricted common stock $ 657 $ — $ 5 Stock options 6,800 624 409 Total stock-based compensation expense $ 7,457 $ 624 $ 414 During the year ended December 31, 2020 the Company modified the terms of certain options granted to a former employee. As a result, the Company recorded a compensation expense of $1,951. There were no modifications during the years ended December 31, 2019 and 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes During the years ended December 31, 2020, 2019 and 2018, the Company did not record a current or deferred income tax expense or benefit. The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows: For the Year Ended December 31, 2020 2019 2018 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % 21.0 % State taxes (2.6 ) 6.2 4.0 Research and development credits 12.5 0.9 1.1 Stock-based compensation (13.6 ) — — Other — (0.5 ) 0.3 Change in valuation allowance (17.3 ) (27.6 ) (26.4 ) Total 0.0 % 0.0 % 0.0 % Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s deferred tax assets consisted of the following: December 31, 2020 2019 Deferred tax assets Net operating loss carryforwards $ 14,069 $ 13,466 Stock-based compensation 1,072 1,024 Research and development credits 1,791 455 Other 53 152 Gross deferred tax assets 16,985 15,097 Less: valuation allowance (16,985 ) (15,097 ) Net deferred tax assets $ — $ — As of December 31, 2020, the Company had federal net operating losses of $53,197 and state net operating loss carryforwards of $52,540. The Company also has federal and state research and development tax credit carryforwards of $1,574 and $274, respectively, which may be used to offset future tax liabilities. Federal net operating losses generated prior to 2018 of $27,522 can be carried back two years and carried forward 20 years. Federal net operating losses generated prior to 2018 and federal tax credit carryforwards will begin to expire in 2033. Federal net operating losses generated post 2017 of $25,675 can be carried forward indefinitely but can only offset 80 percent of annual taxable income. State net operating losses will begin to expire in 2033 and state tax credit carryforwards will begin to expire in 2031. Management has evaluated the positive and negative evidence bearing upon the realizability of the Company’s deferred tax assets, which are comprised principally of net operating loss carryforwards. Based on the Company’s cumulative net losses since inception and projected potential net operating loss for tax purposes in 2021, the Company determined that it is more likely than not that it will not recognize the benefits of the deferred tax assets. As a result, the Company has recorded a full valuation allowance of approximately $16,985 at December 31, 2020. The Company increased its valuation allowance by $1,888 for the year ended December 31, 2020 in order to maintain a full valuation allowance against its deferred tax assets. Under the provisions of Sections 382 and 383 of the Internal Revenue Code (the “IRC”), net operating loss and credit carryforwards and other tax attributes may be subject to limitation if there has been a significant change in ownership of the Company, as defined by the IRC. Future owner or equity shifts, including an initial public offering, could result in limitations on net operating loss and credit carryforwards. The Company performed an analysis through December 31, 2020 pursuant to Section 382 of the IRC to determine whether any limitations might exist on the utilization of net operating losses and other tax attributes. Based on this analysis, the Company has determined that ownership changes occurred in 2014, resulting in an annual limitation of $169 on the use of its net operating losses and other tax attributes generated prior to the ownership change. To the extent that the Company raises additional equity financing or other changes in the ownership interest of significant stockholders occurs, additional tax attributes may become subject to an annual limitation. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The Company files federal and Commonwealth of Massachusetts state income tax returns. The statute of limitations for assessment by the Internal Revenue Service (the “IRS”), and state tax authorities remains open for all tax years ended since the inception of the Company. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the IRS or state tax authorities to the extent utilized in a future period. No federal or state tax audits are currently in process. The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. The Company has not recorded any amounts for unrecognized tax benefits as of December 31, 2020 nor has it recorded any penalties or interest.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	12. Net Loss Per Share Attributable to Common Stockholders The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive: For the Year Ended December 31, 2020 2019 2018 Convertible Preferred Stock — 33,645,447 33,645,447 Stock options to purchase common stock 7,917,783 3,911,633 2,820,000 Non-vested restricted stock — 200,000 200,000

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	13. Related Party Transactions The Company recorded expense of $43, $145 and $0 for consulting services provided by an entity affiliated with the former interim Chief Financial Officer for the years ended December 31, 2020, 2019 and 2018, respectively. Of these amounts, $0 and $20 were included in accrued expenses and other current liabilities as of December 31, 2020 and 2019, respectively. NovaMedica In May 2014, the Company entered into an exclusive license agreement with NovaMedica LLC, an affiliated entity of a stockholder, pursuant to which the Company granted NovaMedica a license to certain intellectual property rights for commercialization of a potential product for the treatment of hepatitis C. In connection with the license, the Company received a license fee of $200 in partial consideration for the grant of the license. Recognition of the license fee had been deferred until both the Company and NovaMedica finalized certain other terms and conditions of the license agreement. The Company and NovaMedica failed to agree on the terms of an amendment to the license agreement and the license agreement was terminated in May 2020. The Company paid a fee of $400 in connection with the termination. There were no other material transactions with related parties.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, or GAAP. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and in these accompanying notes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors and assumptions that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, which include but are not limited to estimates of revenue, accrued research and development expenses, and the valuation of common stock in connection with the issuance of stock-based awards prior to the completion of the IPO. Changes in estimates are recorded in the period in which they become known.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Atea Pharmaceuticals, Inc. and its wholly- owned subsidiary, Atea Pharmaceuticals Securities Corporation. All intercompany amounts have been eliminated in consolidation.
Revenue Recognition	Revenue Recognition As of December 31, 2020, all of the Company’s revenue to date had been collaboration revenue generated from its license agreement with Roche. The Company analyzes its collaboration arrangements to assess whether they are within the scope of Accounting Standards Codification ASC Topic 808, Collaborative Arrangements (“ Research and Development Revenue from Contracts with Customers To determine the appropriate amount of revenue to be recognized for arrangements that the Company determines are within the scope of ASC 606, it performs the following steps: (i) identify the contract(s) with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) each performance obligation is satisfied. ASC 606 requires significant judgment and estimates and results in changes to, but not limited to: (i) the determination of the transaction price, including estimates of variable consideration, (ii) the allocation of the transaction price, including the determination of estimated selling price, and (iii) the pattern of recognition, including the application of proportional performance as a measure of progress on service-related promises and application of point-in-time recognition for supply-related promises. The transaction price is generally comprised of an upfront payment due at contract inception and variable consideration in the form of payments for the Company’s services and materials and milestone payments due upon the achievement of specified events. Other payments the Company could be entitled to include tiered royalties earned when customers recognize net sales of licensed products. The Company considers the existence of any significant financing component within its arrangements and has determined that a significant financing component does not exist in its arrangements as substantive business purposes exist to support the payment structure other than to provide a significant benefit of financing. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes either the expected value method or the most likely amount method to estimate the amount of variable consideration, depending on which method is expected to better predict the amount of consideration to which the Company will be entitled. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. With respect to arrangements that include payments for a development or regulatory milestone payment, the Company evaluates whether the associated event is considered probable of achievement and estimate the amount to be included in the transaction price using the most likely amount method. Milestone payments that are not within the Company’s control or the licensee, such as those dependent upon receipt of regulatory approval, are not considered to be probable of achievement until the triggering event occurs. At the end of each reporting period, the Company re-evaluates the probability of achievement of each milestone and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. For arrangements that include sales-based royalties, including milestone payments based upon the achievement of a certain level of product sales, wherein the license is deemed to be the sole or predominant item to which the payments relate, the Company recognizes revenue upon the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). Consideration that would be received for optional goods and/or services is excluded from the transaction price at contract inception. The Company generally allocates the transaction price to each performance obligation based on a relative standalone selling price basis. The Company develops assumptions that require judgment to determine the standalone selling price for each performance obligation in consideration of applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated research and development costs. However, in certain instances, the Company allocates variable consideration entirely to one or more performance obligation if the terms of the variable consideration relate to the satisfaction of the respective performance obligation and the amount allocated is consistent with the amount the Company would expect to receive for the satisfaction of the respective performance obligation. The Company recognizes revenue based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good or service to the customer. For performance obligations that are satisfied at a point in time, the Company recognizes revenue when control of the goods and/or services is transferred to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company generally uses input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. With respect to arrangements containing a license to its intellectual property that is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from amounts allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which the Company is expected to complete its performance obligations under an arrangement. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. Contract costs The Company recognizes as an asset the incremental costs of obtaining a contract with a customer if the costs are expected to be recovered. The Company has elected the practical expedient in ASC 340, Other Assets and Deferred Costs
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly-liquid investments purchased with maturities of 90 days or less at acquisition to be cash equivalents. Cash and cash equivalents include bank demand deposits and money market funds that invest in U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value.
Concentrations of Credit Risk and Significant Suppliers	Concentrations of Credit Risk and Significant Suppliers Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains its cash and cash equivalents with a financial institution that management believes is creditworthy. The Company’s investment policy includes guidelines on the quality of the financial institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.
Fair Value Measurement	Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Observable inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determination of fair value of the assets or liabilities. Cash, cash equivalents and restricted cash are Level 1 assets which are comprised of funds held in checking and money market accounts. Cash, cash equivalents and restricted cash were recorded at fair value as disclosed in Note 4. The carrying amounts of accounts payable, accrued expenses and unbilled other receivables approximate their fair values due to their short-term maturities.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the asset. The Company estimates the useful life of its assets as follows: Asset Estimated useful life Laboratory equipment Five years Office furniture and fixtures Five years Computer hardware Two years Leasehold improvements Shorter of useful life or remaining lease term Maintenance and repairs that do not improve or extend the life of the respective asset are expensed to operations as incurred. Upon disposal of an asset, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the consolidated statements of operations.
Other Assets	Other Assets Other assets consists primarily of bank deposits of $107, classified as restricted cash, to collateralize a letter of credit.
Impairment of Long-lived Assets	Impairment of Long-lived Assets The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book value of the assets to the estimated undiscounted future net cash flows that the asset is expected to generate. If the estimated undiscounted future net cash flows are less than the book value, the asset is impaired, and the impairment loss to be recognized in income is measured as the amount by which the book value of the asset exceeds its fair value, which is measured based on the estimated discounted future net cash flows that the asset is expected to generate. No impairment losses were recorded during the years ended December 31, 2020, 2019 and 2018.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist principally of costs associated with outsourced research and development activities, including preclinical and clinical development, manufacturing and research conducted by contract research organizations and academic institutions, employee compensation, including stock-based compensation and consulting expenses together with related expenses, professional fees and facility and overhead costs. Facility and overhead costs primarily include the allocation of rent, utility and office-related expenses attributable to research and development personnel. In circumstances where amounts have been paid in advance or in excess of costs incurred, the Company records a prepaid expense, which is expensed as services are performed or goods are delivered. The Company has entered into various research and development contracts with third parties. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase of completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.
Patent Costs	Patent Costs Costs to secure and maintain the Company’s patents are expensed as incurred and are classified as general and administrative expenses in the Company’s consolidated statements of operations.
Stock-based Compensation	Stock-based Compensation Stock-based compensation expense is classified in the consolidated statement of operations in the same manner in which the award recipient’s payroll costs or service payments are classified. Stock-based awards granted to employees and non-employees are measured based on the estimated fair value of the awards using the Black-Scholes option pricing model (“Black-Scholes”). Stock-based compensation expense with respect to awards with service conditions is recognized using the straight-line method over the service period. Stock-based compensation with respect to awards with performance conditions is recognized when satisfaction of the performance conditions is probable. Stock-based compensation is based on awards ultimately expected to vest and, as such, it is reduced by forfeitures. The Company accounts for forfeitures as they occur. Black-Scholes requires the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include: Fair value of common stock — Through October 29, 2020, because there was no public market for the Company’s common stock, the fair value of the Company’s common stock underlying stock-based awards was estimated on each grant date by the board of directors. In the absence of a public trading market for the Company’s common stock prior to its IPO, on each grant date, the Company developed an estimate of the fair value of its common stock based on valuations from an independent third-party valuation firm using information known to the Company on the date of grant, a review of any recent events and their potential impact on the estimated fair value per share of the common stock. The third-party valuations of the Company’s common stock were determined in accordance with the guidelines outlined in the American Institute of Certified Public Accountants Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation, or the Practice Aid. The assumptions used to determine the estimated fair value of the Company’s common stock are based on numerous objective and subjective factors, combined with management judgment, including: • external market conditions affecting the pharmaceutical and biotechnology industry and trends within the industry; • the Company’s stage of development and business strategy; • the rights, preferences and privileges of the Company’s redeemable convertible preferred stock relative to those of its common stock; • the prices at which the Company sold shares of its redeemable convertible preferred stock; • the Company’s financial condition and operating results, including our levels of available capital resources; • the progress of the Company’s research and development efforts; • equity market conditions affecting comparable public companies; and • general U.S. market conditions and the lack of marketability of the Company’s common stock. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In accordance with the Practice Aid, the Company considered the following methods: • Option Pricing Method . Under the option pricing method (“OPM”), shares are valued by creating a series of call options with exercise prices based on the liquidation preferences and conversion terms of each equity class. The estimated fair values of the preferred and common stock are inferred by analyzing these options. • Probability-Weighted Expected Return Method. The probability-weighted expected return method (“PWERM”), is a scenario-based analysis that estimates value per share based on the probability-weighted present value of expected future investment returns, considering each of the possible outcomes available to us, as well as the economic and control rights of each share class. Based on the Company’s early stage of development and other relevant factors, the Company determined that OPM method as well as a hybrid approach of the OPM and the PWERM methods were the most appropriate methods for allocating its enterprise value to determine the estimated fair value of its common stock. In determining the estimated fair value of the Company’s common stock, its board of directors also considered the fact that its stockholders could not freely trade its common stock in the public markets. Accordingly, the Company applied discounts to reflect the lack of marketability of its common stock based on the weighted-average expected time to liquidity. The estimated fair value of our common stock at each grant date reflected a non-marketability discount partially based on the anticipated likelihood and timing of a future liquidity event. Upon the completion of the Company’s initial public offering, the fair value of its common stock is based on the daily closing quoted market price of its common stock. Risk-free interest rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of a stock-based award. Expected term —The expected term represents the period that stock-based awards are expected to be outstanding. Given the Company’s lack of specific history, the expected term for option grants is determined using the simplified method. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the stock-based awards. Expected volatility —Since the Company was privately held through October 29, 2020 and did not have any trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock-based awards. The comparable companies were chosen based on their similar size, stage in the life cycle or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Expected dividend yield —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. The Company also accounts for any modifications to share based payments in accordance with ASC 718.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax base. Deferred tax assets, which relate primarily to the carrying amount of the Company’s net operating loss carryforwards, are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Deferred tax expense or benefit is the result of changes in the deferred tax assets and liabilities. Valuation allowances are established to reduce deferred tax assets where, based upon the available evidence, the Company concludes that it is more-likely-than-not that the deferred tax assets will not be realized. In evaluating its ability to recover deferred tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning and forecasts of future taxable income. Reserves are provided for tax benefits for which realization is uncertain. Such benefits are only recognized when the underlying tax position is considered more-likely-than-not to be sustained on examination by a taxing authority. Interest and penalties related to uncertain tax positions are recognized in the provision of income taxes.
Comprehensive Loss	Comprehensive Loss Comprehensive income (loss) includes net income (loss) as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with equity holders. The Company did not have any items of comprehensive income or loss other than net loss for the years ended December 31, 2020, 2019 and 2018.
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. The Company considers its convertible preferred stock to be participating securities as, in the event a dividend is paid on common stock, the holders of convertible preferred stock would be entitled to receive dividends on a basis consistent with the common stockholders. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible preferred stock as the holders of the convertible preferred stock do not have a contractual obligation to share in losses. Since inception, the Company has incurred recurring operating losses and, as such, under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock. Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that the participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss, as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed by using the weighted-average number of shares of common stock outstanding. Due to net losses for the years ended December 31, 2020, 2019 and 2018, basic and diluted net loss per share attributable to common stockholders were the same, as the effect of all potentially dilutive securities would have been anti-dilutive.
Segments	Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker (the “CODM”), in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its chief executive officer, who manages and allocates resources to the operations on a total company basis. Accordingly, there is a single operating segment and one reportable segment.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently Issued Accounting Pronouncements and Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases The Company plans to use the modified retrospective method of adoption and to elect the available practical expedients. The Company expects that the adoption of the new leasing standard will result in the recognition of a material right to use asset and lease liability in the consolidated balance sheets and does not expect it to have a material impact to its results of operations or statements of cash flows. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”) . Recently Adopted Accounting Pronouncements In November 2018, the FASB , Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Estimated Useful Life	The Company estimates the useful life of its assets as follows: Asset Estimated useful life Laboratory equipment Five years Office furniture and fixtures Five years Computer hardware Two years Leasehold improvements Shorter of useful life or remaining lease term

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of December 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 846,701 $ — $ — $ 846,701 Total cash equivalents $ 846,701 $ — $ — $ 846,701 Fair Value Measurements as of December 31, 2019 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 21,038 $ — $ — $ 21,038 Total cash equivalents $ 21,038 $ — $ — $ 21,038

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net, consist of the following: December 31, 2020 2019 Laboratory equipment $ 5 $ 5 Office furniture and fixtures 13 13 Computer hardware 37 11 Leasehold improvements 125 125 Total property and equipment, at cost 180 154 Less: accumulated depreciation and amortization (132 ) (113 ) Property and equipment, net $ 48 $ 41

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: December 31, 2020 2019 Research and development, including manufacturing and clinical expenditures $ 10,546 $ 1,326 License fees (Note 7) — 200 Professional fees and other 1,079 361 Payroll and payroll related 2,743 — Total accrued expenses and other current liabilities $ 14,368 $ 1,887

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Future Minimum Payments for Operating Leases	As of December 31, 2020, future minimum payments for operating leases are as follows: 2021 $ 340 2022 200 Total future minimum lease payments $ 540

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Summary of Reserved Shares of Common Stock	The Company had the following reserved shares of common stock: December 31, 2020 December 31, 2019 Series A Preferred — 20,000,000 Series B Preferred — 7,592,830 Series C Preferred — 6,052,617 Outstanding options 7,917,783 3,911,633 Options available for future grant 7,059,000 450,567 Shares reserved under ESPP 1,187,000 — 16,163,783 38,007,647

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Options Activity	The following summarizes stock option activity: Number of Shares Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2020 3,911,633 $ 1.50 8.5 $ 3,915 Granted 4,613,861 $ 14.93 Exercised (18,747 ) $ 1.43 Cancelled (588,964 ) $ 6.83 Outstanding at December 31, 2020 7,917,783 $ 6.68 8.6 $ 277,894 Options exercisable at December 31, 2020 3,246,548 $ 1.88 7.4 $ 129,531 Vested or expected to vest at December 31, 2020 7,917,783 $ 6.68 8.6 $ 277,894
Summary of Assumptions Used to Estimate Fair Value of Award	The fair value of each award was estimated using Black-Scholes based on the following assumptions: For the Year Ended December 31, 2020 2019 2018 Risk-free interest rate 0.31 - 0.56% 1.61 - 2.02% 2.45 - 2.89% Expected term 6.25 years 5.52 - 10.0 years 5.52 - 9.96 years Expected volatility 80.0% - 91.7% 49.2% - 78.0% 49.2 % Expected dividend yield 0 % 0 % 0 %
Schedule of Stock-based Compensation Expense	Stock-based compensation expense is classified as follows: For the Year Ended December 31, 2020 2019 2018 Research and development expense $ 3,565 $ 255 $ 192 General and administrative 3,892 369 222 Total stock-based compensation expense $ 7,457 $ 624 $ 414
Summary of Components of Stock-based Compensation Expense	The components of stock-based compensation expense were: For the Year Ended December 31, 2020 2019 2018 Restricted common stock $ 657 $ — $ 5 Stock options 6,800 624 409 Total stock-based compensation expense $ 7,457 $ 624 $ 414

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate	The reconciliation of federal statutory income tax rate to the Company’s effective income tax rate is as follows: For the Year Ended December 31, 2020 2019 2018 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % 21.0 % State taxes (2.6 ) 6.2 4.0 Research and development credits 12.5 0.9 1.1 Stock-based compensation (13.6 ) — — Other — (0.5 ) 0.3 Change in valuation allowance (17.3 ) (27.6 ) (26.4 ) Total 0.0 % 0.0 % 0.0 %
Summary of Principal Components of Deferred Tax Assets	The principal components of the Company’s deferred tax assets consisted of the following: December 31, 2020 2019 Deferred tax assets Net operating loss carryforwards $ 14,069 $ 13,466 Stock-based compensation 1,072 1,024 Research and development credits 1,791 455 Other 53 152 Gross deferred tax assets 16,985 15,097 Less: valuation allowance (16,985 ) (15,097 ) Net deferred tax assets $ — $ —

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Summary of Outstanding Anti-dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share	The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive: For the Year Ended December 31, 2020 2019 2018 Convertible Preferred Stock — 33,645,447 33,645,447 Stock options to purchase common stock 7,917,783 3,911,633 2,820,000 Non-vested restricted stock — 200,000 200,000

Nature of Business - Additional

Nature of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 03, 2020	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Nature of Business [Line Items]
Net proceeds from initial public offering ("IPO")			$ 317,605
Accumulated deficit			65,160	$ 54,213
Cash and cash equivalents			$ 850,117	$ 21,661	$ 34,492
Common Stock
Nature of Business [Line Items]
Shares issued			14,375,000
IPO
Nature of Business [Line Items]
Share price	$ 24
Net proceeds from initial public offering ("IPO")	$ 317,605
IPO | Common Stock
Nature of Business [Line Items]
Shares issued	14,375,000
IPO | Convertible Preferred Stock | Common Stock
Nature of Business [Line Items]
Convertible preferred stock converted into shares	57,932,090
Roche License Agreement
Nature of Business [Line Items]
Non-refundable upfront payment received		$ 350,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Accounting Policies [Line Items]
Recognition method for costs of obtaining a contract	The Company has elected the practical expedient in ASC 340, Other Assets and Deferred Costs, wherein it recognizes the incremental costs of obtaining a contract as an expense when incurred if, at inception, the expected amortization period of the asset that the Company otherwise would have recognized is one year or less.
Incremental cost included in general and administration costs	$ 21,640,000	$ 4,438,000	$ 2,802,000
Restricted cash	107,000	107,000	107,000
Impairment losses	$ 0	$ 0	$ 0
Expected dividend yield	0.00%	0.00%	0.00%
Comprehensive income or loss	$ 0	$ 0	$ 0
Number of operating segments | Segment	1
Number of reportable segments | Segment	1
Other Assets
Accounting Policies [Line Items]
Restricted cash	$ 107,000
Incremental Cost | Roche License
Accounting Policies [Line Items]
Incremental cost included in general and administration costs	$ 7,000,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Estimated Useful Life (Details)	12 Months Ended
	Dec. 31, 2020
Laboratory Equipment
Property Plant And Equipment [Line Items]
Estimated useful life	5 years
Office Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful life	5 years
Computer Hardware
Property Plant And Equipment [Line Items]
Estimated useful life	2 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated useful life	Shorter of useful life or remaining lease term

Collaboration Revenue - Additio

Collaboration Revenue - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Nov. 30, 2020	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Transaction price			$ 350,000,000
Collaboration revenue			48,633,000
Unbilled other receivable			5,815,000
Research and development			38,023,000	$ 10,170,000	$ 6,675,000
Roche License Agreement
Disaggregation Of Revenue [Line Items]
Non-refundable upfront payment received	$ 350,000,000
Capitalized contract Cost			7,000,000
Collaboration revenue			48,633,000
Deferred revenue			301,367,000
Costs reimbursed amount			7,901,000
Unbilled other receivable			5,815,000
Research and development			$ 2,086,000
Roche License Agreement | Maximum | Development and Regulatory
Disaggregation Of Revenue [Line Items]
Milestones receivable upon achievement aggregate		$ 330,000,000
Roche License Agreement | Maximum | Sales Based
Disaggregation Of Revenue [Line Items]
Milestones receivable upon achievement aggregate		$ 320,000,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash equivalents
Total cash equivalents	$ 846,701	$ 21,038
Level 1
Cash equivalents
Total cash equivalents	846,701	21,038
Money Market Funds
Cash equivalents
Total cash equivalents	846,701	21,038
Money Market Funds | Level 1
Cash equivalents
Total cash equivalents	$ 846,701	$ 21,038

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 180	$ 154
Less: accumulated depreciation and amortization	(132)	(113)
Property and equipment, net	48	41
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	5	5
Office Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	13	13
Computer Hardware
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	37	11
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, at cost	$ 125	$ 125

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 19	$ 17	$ 17

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Research and development, including manufacturing and clinical expenditures	$ 10,546	$ 1,326
License fees (Note 7)		200
Professional fees and other	1,079	361
Payroll and payroll related	2,743
Total accrued expenses and other current liabilities	$ 14,368	$ 1,887

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Lease expiration date	Jul. 31, 2022
Rent expense	$ 303,000	$ 305,000	$ 316,000
Restricted cash	107,000	107,000	$ 107,000
Business Development Consulting Agreements | Maximum
Loss Contingencies [Line Items]
Success fee	5,000,000
Other Assets | Letter of Credit
Loss Contingencies [Line Items]
Restricted cash	$ 107,000	$ 107,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2021	$ 340
2022	200
Total future minimum lease payments	$ 540

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2020	May 31, 2020	Dec. 31, 2020	Dec. 31, 2018	Nov. 03, 2020	Dec. 31, 2019	Dec. 31, 2017
Class Of Stock [Line Items]
Shares authorized			0			33,645,447
Shares issued			0			33,645,447
Shares outstanding			0			33,645,447
Net proceeds from issuance of preferred stock			$ 214,116	$ 27,359
Preferred stock, shares authorized			10,000,000			0
Preferred stock, shares issued			0			0
IPO
Class Of Stock [Line Items]
Preferred stock purchase price					$ 24
Convertible Preferred Stock
Class Of Stock [Line Items]
Shares authorized						33,645,447
Shares issued						33,645,447
Shares outstanding				33,645,447		33,645,447	27,592,830
Series A Preferred
Class Of Stock [Line Items]
Shares authorized						20,000,000
Shares issued						20,000,000
Shares outstanding						20,000,000
Preferred stock purchase price						$ 1
Series B Preferred
Class Of Stock [Line Items]
Shares authorized						7,592,830
Shares issued						7,592,830
Shares outstanding						7,592,830
Preferred stock purchase price						$ 3.03
Series C Preferred
Class Of Stock [Line Items]
Shares authorized						6,052,617
Shares issued						6,052,617
Shares outstanding						6,052,617
Preferred stock purchase price						$ 4.56
Series D Preferred
Class Of Stock [Line Items]
Shares authorized		15,313,382
Shares issued		15,313,382
Net proceeds from issuance of preferred stock		$ 106,631
Series D-1 Preferred
Class Of Stock [Line Items]
Shares authorized		8,973,261
Shares issued	8,973,261
Preferred stock purchase price	$ 11.98
Net proceeds from issuance of preferred stock	$ 107,485
Common Stock | IPO
Class Of Stock [Line Items]
Convertible preferred stock converted into shares					57,932,090

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Common stock, shares authorized	300,000,000	53,070,161
Common stock, shares issued	82,436,937	10,091,100
Common stock, shares outstanding	82,436,937	10,091,100
Common stock voting rights per share	On all matters to be voted upon by the holders of common stock, holders of common stock are entitled to one vote per share.

Common Stock - Summary of Reser

Common Stock - Summary of Reserved Shares of Common Stock (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	16,163,783	38,007,647
Series A Preferred
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance		20,000,000
Series B Preferred
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance		7,592,830
Series C Preferred
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance		6,052,617
Outstanding options
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	7,917,783	3,911,633
Options available for future grant
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	7,059,000	450,567
Shares reserved under ESPP
Class Of Stock [Line Items]
Common stock, capital shares reserved for future issuance	1,187,000

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Jan. 31, 2021	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance	16,163,783				16,163,783	38,007,647
Share-based compensation expense					$ 657
Unrecognized compensation expense	$ 33,240				$ 33,240
Remaining weighted average period for recognize compensation expense					3 years 8 months 12 days
Weighted average grant date fair value per option granted					$ 14.93	$ 1.19	$ 0.77
Fair value assumptions, method used					Black-Scholes
Share-based compensation expense					$ 7,457	$ 624	$ 414
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares	0				0
Restricted Stock | Consultant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, granted		200,000
Number of shares vest					20,000
Share-based compensation expense					$ 657
Number of shares forfeited					180,000
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting contractual term					10 years
Share-based compensation expense					$ 6,800	$ 624	$ 409
Stock Options | Former Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense					$ 1,951
2020 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance	7,059,000				7,059,000
2020 Incentive Award Plan | Annual Increase
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares of common stock Outstanding				5.00%
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance				1,187,000
Stock option plan, effective date				Oct. 29, 2020
Shares issued	0
Subsequent Event | 2020 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increased number of shares available under incentive plan			4,130,847
Maximum | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting service period					4 years
Maximum | 2020 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant				7,924,000
Maximum | 2013 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant								7,807,200
Minimum | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting service period					3 years

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Number of Shares, Outstanding	3,911,633
Number of Shares, Granted	4,613,861
Number of Shares, Exercised	(18,747)
Number of Shares, Cancelled	(588,964)
Number of Shares, Outstanding	7,917,783	3,911,633
Number of Shares, Options exercisable	3,246,548
Number of Shares, Vested or expected to vest	7,917,783
Weighted Average Exercise Price Per Share
Weighted Average Exercise Price Per Share, Outstanding	$ 1.50
Weighted Average Exercise Price Per Share, Granted	14.93
Weighted Average Exercise Price Per Share, Exercised	1.43
Weighted Average Exercise Price Per Share, Cancelled	6.83
Weighted Average Exercise Price Per Share, Outstanding	6.68	$ 1.50
Weighted Average Exercise Price Per Share, Options exercisable	1.88
Weighted Average Exercise Price Per Share, Vested or expected to vest	$ 6.68
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term (years), Outstanding	8 years 7 months 6 days	8 years 6 months
Weighted Average Remaining Contractual Term (years), Options exercisable	7 years 4 months 24 days
Weighted Average Remaining Contractual Term (years), Vested or expected to vest	8 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding	$ 277,894	$ 3,915
Aggregate Intrinsic Value, Options exercisable	129,531
Aggregate Intrinsic Value, Vested or expected to vest	$ 277,894

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Assumptions Used to Estimate Fair Value of Award (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	0.31%	1.61%	2.45%
Risk-free interest rate, Maximum	0.56%	2.02%	2.89%
Expected term	6 years 3 months
Expected volatility			49.20%
Expected volatility, Minimum	80.00%	49.20%
Expected volatility, Maximum	91.70%	78.00%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term		5 years 6 months 7 days	5 years 6 months 7 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term		10 years	9 years 11 months 15 days

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,457	$ 624	$ 414
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3,565	255	192
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 3,892	$ 369	$ 222

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Components of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,457	$ 624	$ 414
Restricted Common Stock
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	657		5
Stock Options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 6,800	$ 624	$ 409

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Deferred income tax expense (benefit)	$ 0	$ 0	$ 0
Current income tax expense (benefit)	0	0	$ 0
Valuation allowance	16,985,000	$ 15,097,000
Increase in valuation allowance	1,888,000
Amount of annual limit on use of net operating losses and other tax attributes	$ 169,000
Percentage of tax benefits likelihood being realized upon settlement	greater than 50%
Unrecognized tax benefits	$ 0
Penalties or interest	0
Federal
Income Tax Disclosure [Line Items]
Net operating losses	53,197,000
Research and development tax credit carryforwards	$ 1,574,000
Tax credit carryforwards expiration year	2033
Federal | Prior to 2018
Income Tax Disclosure [Line Items]
Net operating losses	$ 27,522,000
Net operating losses carried back period	2 years
Net operating losses carried forward period	20 years
Net operating losses carryforwards expiration year	2033
Federal | Post 2017
Income Tax Disclosure [Line Items]
Net operating losses	$ 25,675,000
Net operating losses carryforwards offset percent of annual taxable income	80.00%
State
Income Tax Disclosure [Line Items]
Net operating losses	$ 52,540,000
Research and development tax credit carryforwards	$ 274,000
Net operating losses carryforwards expiration year	2033
Tax credit carryforwards expiration year	2031

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Expected income tax benefit at the federal statutory rate	21.00%	21.00%	21.00%
State taxes	(2.60%)	6.20%	4.00%
Research and development credits	12.50%	0.90%	1.10%
Stock-based compensation	(13.60%)
Other		(0.50%)	0.30%
Change in valuation allowance	(17.30%)	(27.60%)	(26.40%)
Total	0.00%	0.00%	0.00%

Income Taxes - Summary of Princ

Income Taxes - Summary of Principal Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforwards	$ 14,069	$ 13,466
Stock-based compensation	1,072	1,024
Research and development credits	1,791	455
Other	53	152
Gross deferred tax assets	16,985	15,097
Less: valuation allowance	(16,985)	(15,097)
Net deferred tax assets	$ 0	$ 0

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Summary of Outstanding Anti-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
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share		33,645,447	33,645,447
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share	7,917,783	3,911,633	2,820,000
Non-vested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted net loss per share		200,000	200,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	May 31, 2020	May 31, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
License Agreement | NovaMedica LLC
Related Party Transaction [Line Items]
License fee received		$ 200
Payment for termination fee	$ 400
Consulting Services | Former Chief Financial Officer
Related Party Transaction [Line Items]
Related party transaction expense			$ 43	$ 145	$ 0
Consulting Services | Former Chief Financial Officer | Accrued Expenses and Other Current Liabilities
Related Party Transaction [Line Items]
Related party transaction expense			$ 0	$ 20