Atea Pharmaceuticals (AVIR) 10-Q 8 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Nov. 07, 2023
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	AVIR
Entity Registrant Name	ATEA PHARMACEUTICALS, INC.
Entity Central Index Key	0001593899
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		83,435,513
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-39661
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-0574869
Entity Address, Address Line One	225 Franklin Street
Entity Address, Address Line Two	Suite 2100
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
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 137,886	$ 188,460
Marketable securities	457,240	458,249
Prepaid expenses and other current assets	8,190	14,213
Total current assets	603,316	660,922
Property and equipment, net	1,393	1,705
Restricted cash		198
Other assets	1,396	1,494
Operating lease right-of-use assets, net	1,970	2,389
Total assets	608,075	666,708
Current liabilities
Accounts payable	395	2,551
Accrued expenses and other current liabilities	17,748	15,206
Current portion of operating lease liabilities	750	721
Total current liabilities	18,893	18,478
Operating lease liabilities	1,835	2,403
Income taxes payable	5,617	5,255
Total liabilities	26,345	26,136
Commitments and contingencies (see Note 12)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 10,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value; 300,000,000 shares authorized; 83,435,513 and 83,287,639 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively	83	83
Additional paid-in capital	738,580	701,052
Accumulated other comprehensive loss	(262)	(684)
Accumulated deficit	(156,671)	(59,879)
Total stockholders’ equity	581,730	640,572
Total liabilities and stockholders’ equity	$ 608,075	$ 666,708

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	83,435,513	83,287,639
Common stock, shares outstanding	83,435,513	83,287,639

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses:
Research and development	$ 28,181	$ 4,905	$ 79,198	$ 54,396
General and administrative	12,604	11,376	38,391	36,355
Total operating expenses	40,785	16,281	117,589	90,751
Loss from operations	(40,785)	(16,281)	(117,589)	(90,751)
Interest income and other, net	7,864	4,382	21,466	5,560
Loss before income taxes	(32,921)	(11,899)	(96,123)	(85,191)
Income tax benefit (expense)	(221)	3,833	(669)	3,713
Net loss	(33,142)	(8,066)	(96,792)	(81,478)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale investments	48	(855)	422	(855)
Comprehensive loss	$ (33,094)	$ (8,921)	$ (96,370)	$ (82,333)
Net loss per share - basic and diluted
Basic	$ (0.40)	$ (0.10)	$ (1.16)	$ (0.98)
Diluted	$ (0.40)	$ (0.10)	$ (1.16)	$ (0.98)
Weighted-average number of common shares used in computing net loss per share - basic and diluted
Basic	83,399,769	83,258,537	83,374,328	83,231,146
Diluted	83,399,769	83,258,537	83,374,328	83,231,146

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated other comprehensive loss	Retained Earnings (Accumulated Deficit)
Balance at Dec. 31, 2021	$ 710,077	$ 83	$ 653,964		$ 56,030
Balance, shares at Dec. 31, 2021		83,102,730
Issuance of common stock upon exercise of stock options	223		223
Issuance of common stock upon exercise of stock options, shares		154,861
Stock-based compensation expense	11,661		11,661
Net loss	(42,077)				(42,077)
Balance at Mar. 31, 2022	679,884	$ 83	665,848		13,953
Balance, shares at Mar. 31, 2022		83,257,591
Balance at Dec. 31, 2021	710,077	$ 83	653,964		56,030
Balance, shares at Dec. 31, 2021		83,102,730
Net loss	(81,478)
Balance at Sep. 30, 2022	663,187	$ 83	689,407	$ (855)	(25,448)
Balance, shares at Sep. 30, 2022		83,287,639
Balance at Mar. 31, 2022	679,884	$ 83	665,848		13,953
Balance, shares at Mar. 31, 2022		83,257,591
Stock-based compensation expense	11,908		11,908
Net loss	(31,335)				(31,335)
Balance at Jun. 30, 2022	660,457	$ 83	677,756		(17,382)
Balance, shares at Jun. 30, 2022		83,257,591
Issuance of common stock upon exercise of stock options	7		7
Issuance of common stock upon exercise of stock options, shares		1,012
Issuance of common stock under employee stock purchase plan	140		140
Issuance of common stock under employee stock purchase plan, shares		29,036
Stock-based compensation expense	11,504		11,504
Other comprehensive income	(855)			(855)
Net loss	(8,066)				(8,066)
Balance at Sep. 30, 2022	663,187	$ 83	689,407	(855)	(25,448)
Balance, shares at Sep. 30, 2022		83,287,639
Balance at Dec. 31, 2022	640,572	$ 83	701,052	(684)	(59,879)
Balance, shares at Dec. 31, 2022		83,287,639
Issuance upon vesting of restricted stock units, shares		53,935
Issuance of common stock under employee stock purchase plan	165		165
Issuance of common stock under employee stock purchase plan, shares		57,803
Stock-based compensation expense	12,535		12,535
Other comprehensive income	377			377
Net loss	(35,467)				(35,467)
Balance at Mar. 31, 2023	618,182	$ 83	713,752	(307)	(95,346)
Balance, shares at Mar. 31, 2023		83,399,377
Balance at Dec. 31, 2022	640,572	$ 83	701,052	(684)	(59,879)
Balance, shares at Dec. 31, 2022		83,287,639
Net loss	(96,792)
Balance at Sep. 30, 2023	581,730	$ 83	738,580	(262)	(156,671)
Balance, shares at Sep. 30, 2023		83,435,513
Balance at Mar. 31, 2023	618,182	$ 83	713,752	(307)	(95,346)
Balance, shares at Mar. 31, 2023		83,399,377
Stock-based compensation expense	12,353		12,353
Other comprehensive income	(3)			(3)
Net loss	(28,183)				(28,183)
Balance at Jun. 30, 2023	602,349	$ 83	726,105	(310)	(123,529)
Balance, shares at Jun. 30, 2023		83,399,377
Issuance of common stock under employee stock purchase plan	92		92
Issuance of common stock under employee stock purchase plan, shares		36,136
Stock-based compensation expense	12,383		12,383
Other comprehensive income	48			48
Net loss	(33,142)				(33,142)
Balance at Sep. 30, 2023	$ 581,730	$ 83	$ 738,580	$ (262)	$ (156,671)
Balance, shares at Sep. 30, 2023		83,435,513

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net loss	$ (96,792)	$ (81,478)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	37,271	35,073
Depreciation and amortization expense	312	156
Accretion of premium and discounts on marketable securities	(11,101)	(2,465)
Changes in operating assets and liabilities:
Accounts receivable		(4,514)
Prepaid expenses and other current assets	6,023	(4,484)
Other assets	98
Accounts payable	(2,156)	(3,416)
Accrued expenses and other liabilities	2,904	(39,109)
Operating lease liabilities	(120)	800
Net cash used in operating activities	(63,561)	(99,437)
Cash flows from investing activities
Additions to property and equipment		(1,943)
Purchases of marketable securities	(515,132)	(486,955)
Sales and maturities of marketable securities	527,664	0
Net cash provided by (used in) investing activities	12,532	(488,898)
Cash flows from financing activities
Proceeds from issuance of common stock for exercise of stock options		230
Proceeds from issuance of common stock under ESPP	257	140
Net cash provided by financing activities	257	370
Net decrease in cash, cash equivalents and restricted cash	(50,772)	(587,965)
Cash, cash equivalents and restricted cash at the beginning of period	188,658	764,680
Cash, cash equivalents and restricted cash at the end of period	137,886	176,715
Cash, cash equivalents and restricted cash at the end of period:
Cash and cash equivalents	137,886	176,410
Restricted cash		305
Total cash, cash equivalents and restricted cash	$ 137,886	176,715
Supplemental cash flow information:
Right of use assets obtained in exchange for operating lease liabilities		$ 2,938

Organization

Organization	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Business Overview Atea Pharmaceuticals, Inc., together with its subsidiary, Atea Pharmaceuticals Securities Corporation, ("Atea" or the "Company") is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing antiviral therapeutics to improve the lives of patients suffering from severe viral infections. Currently, Atea is conducting a Phase 3 clinical trial evaluating bemnifosbuvir for the treatment of COVID-19. Atea is also currently conducting a Phase 2 clinical trial evaluating the combination of bemnifosbuvir and ruzasvir for the treatment of hepatitis C. Liquidity and Capital Resources As of September 30, 2023, the Company had $ 595.1 million in cash, cash equivalents and marketable securities, which the Company believes will be sufficient to fund its operations for a period through at least twelve months from the issuance date of these unaudited condensed consolidated financial statements. In November 2021, the Company entered into an open market sales agreement (“Sales Agreement”) with Jefferies LLC (“Jefferies”), under which the Company may from time to time offer and sell shares of its common stock for an aggregate offering price of up to $ 200.0 million, through or to Jefferies, acting as sales agent or principal. The shares will be offered and sold under the Company’s shelf registration statement on Form S-3 and a related prospectus filed with the Securities and Exchange Commission (“SEC”) on November 24, 2021, as amended. The Company has agreed to pay Jefferies a commission of 3.0 % of the aggregate gross proceeds from each sale of shares, reimburse legal fees and disbursements and provide Jefferies with customary indemnification and contribution rights. As of September 30, 2023, no shares have been issued under the Sales Agreement. Risks and Uncertainties 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 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, and 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 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 new 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 stockholders. The Company is also subject to risks associated with the continued evolution of COVID-19 and its consequences, 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. Geopolitical events, including civil or political unrest and terrorism, have resulted in a significant disruption of global business and financial markets. In addition, recent or future market volatility, increased inflation and higher interest rates, if sustained, may increase our cost of financing and may restrict our access to potential sources of future liquidity.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The unaudited interim condensed consolidated financial statements of the Company included herein have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) as found in the Accounting Standards Codification (“ASC”), Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”) and the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such SEC rules and regulations. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2023. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2023, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, the condensed consolidated statements of stockholders’ equity for the three and nine month period ended September 30, 2023 and 2022, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2023, the results of its operations for the three and nine months ended September 30, 2023 and 2022 and its cash flows for the nine months ended September 30, 2023 and 2022. The results for the nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023, or any other interim period. Use of Estimates 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 accrued research and development expenses, valuation of marketable securities, the valuation of stock-based awards, valuation of operating lease right-of-use assets and lease liabilities and income taxes. 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. Significant Accounting Policies There were no changes in the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on February 28, 2023. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standard Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. The Company does not believe that the adoption of recently issued standards have or may have a material impact on its consolidated financial statements and disclosures.

Collaboration Agreement

Collaboration Agreement	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Collaboration Agreement	3. Collaboration Agreement Background In October 2020, the Company entered into a License Agreement (the “Roche License Agreement”) with F. Hoffmann-LaRoche Ltd. and Genentech, Inc. (together, “Roche”) under which the Company granted an exclusive license for certain development and commercialization rights related to bemnifosbuvir outside of the United States (other than for certain HCV uses) to Roche. On November 12, 2021, Roche provided the Company with a notice of termination of the Roche License Agreement which became effective in February 2022. Upon termination, the rights and licenses granted by the Company to Roche under the Roche License Agreement were returned to the Company, resulting in the Company having all rights to continue the clinical development and future commercialization of bemnifosbuvir worldwide. Global development plan activities and related cost sharing between the parties continued through the effective date of the termination. The activities undertaken as a part of the global development plan were accounted for under ASC 808. Expenses incurred and reimbursements made or received from Roche were accounted for pursuant to ASC 730, Research and Development . As such, the Company was expensing costs as incurred, including any reimbursements made to Roche, and recognizing reimbursement received from Roche as a reduction of research and development expense through the effective date of the termination. For the three and nine months ended September 30, 2022, the Company recorded a credit to research and development expense of $ 14,572 and $ 5,838 , respectively. For the three and nine months ended September 30, 2023, the Company recorded a credit to research and development expense of $ 3,748 and $ 12,625 , respectively. The credits recorded represent changes in estimates as a result of close out activities and related reporting of amounts incurred by Roche associated with the global development plan. Included in prepaid expenses and other current assets as of September 30, 2023 is a net balance due from Roche of $ 3,748 .

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2023
Debt Securities, Available-for-Sale [Abstract]
Marketable Securities	4. Marketable Securities As of September 30, 2023 Amortized Cost Unrealized Gain Unrealized Losses Fair Value Marketable Securities US Treasury obligations $ 149,721 $ 8 $ ( 104 ) $ 149,625 US Government agency securities 171,645 55 ( 106 ) 171,594 Commercial paper 84,281 — — 84,281 Corporate bonds 51,855 — ( 115 ) 51,740 Total $ 457,502 $ 63 $ ( 325 ) $ 457,240 As of December 31, 2022 Amortized Cost Unrealized Gain Unrealized Losses Fair Value Marketable Securities US Treasury obligations $ 59,422 $ — $ ( 304 ) $ 59,118 US Government agency securities 15,000 — ( 59 ) 14,941 Commercial paper 310,433 — — 310,433 Corporate bonds 61,504 — ( 255 ) 61,249 Asset-backed securities 12,574 — ( 66 ) 12,508 Total $ 458,933 $ — $ ( 684 ) $ 458,249 As of September 30, 2023, the Company held 39 securities that were in an unrealized loss position of $ 325 with an aggregate fair value of $ 272,304 . The Company has the intent and ability to hold such securities until recovery. As a result, the Company did not record any charges for credit-related impairments for its marketable debt securities for the three and nine months ended September 30, 2023. None of the securities had remaining maturities longer than one year as of September 30, 2023. The Company received proceeds of $ 527,664 from sales and maturities of marketable securities during the nine months ended September 30, 2023. There were no sales and maturities of marketable securities during the nine months ended September 30, 2022.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	5. 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 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 131,656 $ — $ — $ 131,656 Commercial paper — 5,983 — 5,983 Marketable Securities US Treasury obligations — 149,625 — 149,625 US Government agency securities — 171,594 — 171,594 Commercial paper — 84,281 — 84,281 Corporate bonds — 51,740 — 51,740 Total $ 131,656 $ 463,223 $ — $ 594,879 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 167,584 $ — $ — $ 167,584 Marketable Securities US Treasury obligations — 59,118 — 59,118 US Government agency securities — 14,941 — 14,941 Commercial paper — 310,433 — 310,433 Corporate bonds — 61,249 — 61,249 Asset-backed securities — 12,508 — 12,508 Total $ 167,584 $ 458,249 $ — $ 625,833 The Company’s assets with fair value categorized as Level 1 within the fair value hierarchy include money market funds. Money market funds are publicly traded mutual funds and are presented as cash equivalents on the unaudited condensed consolidated balance sheets as of September 30, 2023 and December 31, 2022. The Company's assets with fair value categorized as Level 2 within the fair value hierarchy include commercial paper, governmental and corporate bonds and asset-backed securities with fair values determined by utilizing information from third party pricing sources for identical or similar assets and liabilities in active market. There were no transfers among Level 1, Level 2 or Level 3 categories in the three and nine months ended September 30, 2023.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2023
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: September 30, December 31, Research and development, including manufacturing and clinical expenditures $ 11,848 $ 7,667 Income taxes — 99 Payroll and payroll related 5,002 6,459 Professional fees and other 898 981 Total accrued expenses and other current liabilities $ 17,748 $ 15,206

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Common Stock	7. Common Stock At September 30, 2023, the authorized capital of the Company included 300,000,000 shares of common stock, of which 83,435,513 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 have no preemptive, redemption or conversion rights.

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	8. Stock-based Compensation In October 2020, the Company’s shareholders approved the Company’s 2020 Incentive Award Plan (“2020 Plan”). The 2020 Plan initially provided for the issuance of up to 7,924,000 shares of common stock and for the grant of incentive stock options or other incentive awards to employees, officers, directors and consultants of the Company. The number of shares of common stock that may be issued under the 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. Through December 31, 2022, the shares available under the plan were increased by 8,285,983 shares. In January 2023, the shares of the Company's common stock available under the 2020 Plan were increased by 4,164,381 shares. As of September 30, 2023, 6,521,704 shares of common stock were available for future issuance under the 2020 Plan. The 2020 Plan replaced and is the successor of the Company’s 2013 Equity Incentive Plan, as amended (“2013 Plan”). Upon any cancellation of outstanding option awards to purchase up to 5,982,266 shares of common stock under the 2013 Plan, such shares will be made available for grant under the 2020 Plan. Restricted Stock Units During the nine months ended September 30, 2023 and 2022, respectively, the Company granted 2,264,700 and 182,350 restricted stock units to employees and directors under the 2020 Plan with an aggregate grant date fair market value of $ 10,384 and $ 1,302 , respectively. The restricted stock unit awards vest in three annual installments. Below is the activity related to restricted stock units for the nine months ended September 30, 2023. Number of Weighted Average Outstanding at January 1, 2023 161,750 $ 7.14 Granted 2,264,700 $ 4.59 Released ( 53,935 ) $ 7.14 Cancelled ( 34,998 ) $ 5.42 Unvested shares at September 30, 2023 2,337,517 $ 4.69 As of September 30, 2023, total unrecognized compensation expense related to restricted stock units was $ 8,408 , which amount is being recognized over a remaining weighted average period of 2.2 years. Performance-based Restricted Stock Units During the nine months ended September 30, 2022, the Company granted 742,070 performance-based restricted stock units to employees under the 2020 Plan with an aggregate grant date fair value of $ 5,298 . The performance stock unit awards provide for a performance period from February 1, 2022 through January 31, 2025 to achieve up to six defined performance metrics. The percentage of each award eligible to vest will be determined based on the number of metrics achieved during the performance period and may range from 0 % to 200 %. The Company has not recognized any compensation expense through September 30, 2023, as the minimum performance criteria had not been deemed probable. The vesting of any eligible awards will occur in equal installments on January 31, 2025 and January 31, 2026. During the year ended December 31, 2022, 17,100 performance-based restricted stock units were canceled due to terminations. The following table summarizes the activity related to performance-based restricted stock units for the nine months ended September 30, 2023. Number of Weighted Average Outstanding at January 1, 2023 724,970 $ 7.14 Granted — $ — Released — $ — Cancelled — $ — Unvested shares at September 30, 2023 724,970 $ 7.14 Stock Options The following table summarizes stock option activity: Number of Weighted Weighted Aggregate Outstanding at January 1, 2023 13,632,278 $ 18.48 7.7 $ 10,937 Granted 3,766,550 $ 4.49 Exercised — $ — Cancelled ( 392,509 ) $ 21.46 Outstanding at September 30, 2023 17,006,319 $ 15.31 7.4 $ 4,913 Vested and expected to vest at September 30, 2023 17,006,319 $ 15.31 7.4 $ 4,913 Vested and exercisable at September 30, 2023 10,208,053 $ 16.37 6.6 $ 4,874 The Company granted 125,000 and 358,500 options during the three months ended September 30, 2023 and 2022 with an aggregate grant date fair value of $ 295 and $ 2,188 , respectively. The Company granted 3,766,550 and 3,740,917 options during the nine months ended September 30, 2023 and 2022 with an aggregate grant date fair value of $ 12,341 and $ 19,217 , respectively. 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 four years and have a contractual term of ten years . As of September 30, 2023, total unrecognized compensation expense related to stock option awards was $ 66,168 , which amount is being recognized over a remaining weighted average period of 2.4 years. Employee Stock Purchase Plan In October 2020, the Company’s shareholders approved the Employee Stock Purchase Plan ("ESPP"), which became effective upon the closing of the Company’s IPO in November 2020. The Company initially reserved a total of 1,187,000 shares of its common stock for issuance under the ESPP. The ESPP provides that the number of shares reserved and available for issuance under the ESPP will be increased on January 1 of each calendar year by 1 % of the number of shares of the Company's common stock issued and outstanding on the immediately preceding December 31 or such lesser amount as specified by the board of directors. Through December 31, 2022, there was no increase in the number of shares reserved for issuance under the ESPP. In January 2023, the number of shares of the Company's common stock available for issuance under the ESPP was increased by 832,876 shares. The Company issued 36,136 and 93,939 shares for proceeds of $ 92 and $ 257 during the three and nine months ended September 30, 2023, respectively. The Company issued 26,036 shares for proceeds of $ 140 during the three and nine months ended September 30, 2022. Stock-based Compensation Expense Stock-based compensation expense by award type included within the unaudited condensed consolidated statements of operations and comprehensive loss was as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Stock options $ 11,295 $ 11,362 $ 34,592 $ 34,727 Restricted stock units 1,087 97 2,590 256 Performance-based stock units — — — — Employee stock purchase plan 1 45 89 90 Total stock-based compensation expense $ 12,383 $ 11,504 $ 37,271 $ 35,073 Stock-based compensation expense is classified as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Research and development expense $ 5,564 $ 5,370 $ 17,037 $ 16,390 General and administrative 6,819 6,134 20,234 18,683 Total stock-based compensation expense $ 12,383 $ 11,504 $ 37,271 $ 35,073

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	9. Net Loss Per Share Basic and diluted earnings per share are calculated as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Net loss $ ( 33,142 ) $ ( 8,066 ) $ ( 96,792 ) $ ( 81,478 ) Weighted average common shares outstanding, basic and diluted 83,399,769 83,258,537 83,374,328 83,231,146 Net loss per share, basic and diluted $ ( 0.40 ) $ ( 0.10 ) $ ( 1.16 ) $ ( 0.98 ) Stock options for the purchase of 17,006,319 shares, 2,337,517 restricted stock units and 724,970 performance-based restricted stock units were excluded from the computation of the net loss per share for the three and nine months ended September 30, 2023, due to the net loss during the periods as their effect is antidilutive. Stock options for the purchase of 13,490,691 shares, 161,750 restricted stock units and 724,970 performance-based restricted stock units were excluded from the computation of the net loss per share for the three and nine months ended September 30, 2022, due to the net loss during the periods as their effect is antidilutive .

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Leases	10. Leases The Company has a non-cancelable operating lease agreement for its office space in Boston, Massachusetts at 225 Franklin Street ("225 Lease"). The 225 Lease commencement date was January 1, 2022 and the 225 Lease runs through December 31, 2026 . The 225 Lease does no t contain any options for renewal or extension. In connection with the 225 Lease commencement, the Company recorded a right-of-use asset and operating lease liability of $ 2,938 and $ 2,873 as of January 1, 2022. The following assets and liabilities are recorded on the Company’s consolidated balance sheet as of September 30, 2023. As of September 30, 2023 Right-of-use asset $ 1,970 Current lease liability 750 Non-current lease liability 1,835 Future minimum payments under the 225 Lease, currently the Company’s only operating lease as of September 30, 2023 were as follows. As of September 30, 2023 Remainder of 2023 $ 201 2024 821 2025 838 2026 855 Total lease payments 2,715 Less amount representing implied interest ( 130 ) Total lease liability $ 2,585 Current portion of operating lease liabilities $ 750 Non-current portion of operating lease liabilities $ 1,835 For the three and nine months ended September 30, 2023, the Company recorded operating lease costs of $ 162 and $ 485 , respectively, relating to its operating lease agreements. For the three and nine months ended September 30, 2022, the Company recorded operating lease costs of $ 185 and $ 649 , respectively, relating to its operating lease agreements.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The Company recorded income tax expense of $ 221 and $ 669 for the three and nine months ended September 30, 2023, respectively. The Company recorded a net benefit from income taxes of $ 3,833 and $ 3,713 for the three and nine months ended September 30, 2022. The benefit from income taxes was primarily the result of changes in estimates between the Company's initial provision for 2021 income taxes and the actual amounts reflected in income tax returns as filed. The Company maintained a full valuation allowance for the three months ended September 30, 2023 and 2022 due to uncertainty regarding its ability to utilize deferred tax assets.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies License Agreement In December 2021, the Company entered into a license agreement with MSD International GmbH, an affiliate of Merck & Co, Inc. (“Merck”) (“Merck License Agreement”) for the development, manufacture and commercialization of ruzasvir. Ruzasvir is the NS5A inhibitor the Company is developing in combination with bemnifosbuvir for the treatment of HCV. Pursuant to the terms of the Merck License Agreement, the Company obtained from Merck an exclusive (subject to certain reserved rights to conduct internal research), sublicensable, and worldwide license under certain Merck patents and know-how to research, develop, manufacture, have manufactured, use, import, export, sell, offer for sale, and otherwise commercialize ruzasvir or products containing ruzasvir (each a “Product”) for all therapeutic or prophylactic uses in humans. In addition to a non-refundable upfront payment that the Company made in February 2022, the Company will be required to pay Merck milestone payments upon its achievement of certain development, regulatory and sales-based milestones. Additionally, the Company will pay Merck tiered royalties based on annual net sales of Products ranging from high single digits to mid-teens percentages. The Company’s royalty payment obligations will continue until the later of (i) the expiration of the last to expire valid claim of a licensed Merck patent claiming such Product and (ii) a period of years after the first commercial sale of such Product in such country. The Company may terminate the Merck License Agreement for convenience upon prior written notice. The first potential milestone would be payable upon the commencement of a Phase 3 clinical trial. Contingent Consulting Fee 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 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.

Benefit Plan

Benefit Plan	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Benefit Plan	13. Benefit Plan The Company's defined contribution plan under Section 401(k) of the Internal Revenue Code (“401(k) Plan”) covers substantially all employees who meet minimum age and service requirements. Under the terms of the 401(k) Plan, the Company records matching contributions up to 4 % of the participant’s eligible compensation. During the three and nine months ended September 30, 2023, the Company recognized expense of $ 105 and $ 642 , respectively, relating to matching contributions to the 401(k) Plan. During the three and nine months ended September 30, 2022, the Company recognized expense of $ 97 and $ 463 , respectively, relating to matching contributions to the 401(k) Plan.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	14. Related Party Transactions The Company is party to a consulting agreement with an entity controlled by one of its directors. The agreement provides for an annual retainer of $ 110 . The Company recognized expense in the amount of $ 27 and $ 81 for each of the three and nine months ended September 30, 2023 and 2022, respectively. In June 2022, the Company entered into a consulting agreement with one of its directors. The Company recognized expense of zero and $ 1 in connection with this consulting agreement during the three and nine months ended September 30, 2022. No expense was recognized in connection with this agreement for the three and nine months ended September 30, 2023.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited interim condensed consolidated financial statements of the Company included herein have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) as found in the Accounting Standards Codification (“ASC”), Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”) and the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such SEC rules and regulations. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2023.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2023, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2023 and 2022, the condensed consolidated statements of stockholders’ equity for the three and nine month period ended September 30, 2023 and 2022, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2023, the results of its operations for the three and nine months ended September 30, 2023 and 2022 and its cash flows for the nine months ended September 30, 2023 and 2022. The results for the nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023, or any other interim period.
Use of Estimates	Use of Estimates 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 accrued research and development expenses, valuation of marketable securities, the valuation of stock-based awards, valuation of operating lease right-of-use assets and lease liabilities and income taxes. 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.
Significant Accounting Policies	Significant Accounting Policies There were no changes in the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on February 28, 2023.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standard Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. The Company does not believe that the adoption of recently issued standards have or may have a material impact on its consolidated financial statements and disclosures.

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2023
Debt Securities, Available-for-Sale [Abstract]
Schedule of Marketable Securities	As of September 30, 2023 Amortized Cost Unrealized Gain Unrealized Losses Fair Value Marketable Securities US Treasury obligations $ 149,721 $ 8 $ ( 104 ) $ 149,625 US Government agency securities 171,645 55 ( 106 ) 171,594 Commercial paper 84,281 — — 84,281 Corporate bonds 51,855 — ( 115 ) 51,740 Total $ 457,502 $ 63 $ ( 325 ) $ 457,240 As of December 31, 2022 Amortized Cost Unrealized Gain Unrealized Losses Fair Value Marketable Securities US Treasury obligations $ 59,422 $ — $ ( 304 ) $ 59,118 US Government agency securities 15,000 — ( 59 ) 14,941 Commercial paper 310,433 — — 310,433 Corporate bonds 61,504 — ( 255 ) 61,249 Asset-backed securities 12,574 — ( 66 ) 12,508 Total $ 458,933 $ — $ ( 684 ) $ 458,249

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
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 Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 131,656 $ — $ — $ 131,656 Commercial paper — 5,983 — 5,983 Marketable Securities US Treasury obligations — 149,625 — 149,625 US Government agency securities — 171,594 — 171,594 Commercial paper — 84,281 — 84,281 Corporate bonds — 51,740 — 51,740 Total $ 131,656 $ 463,223 $ — $ 594,879 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Cash equivalents Money market funds $ 167,584 $ — $ — $ 167,584 Marketable Securities US Treasury obligations — 59,118 — 59,118 US Government agency securities — 14,941 — 14,941 Commercial paper — 310,433 — 310,433 Corporate bonds — 61,249 — 61,249 Asset-backed securities — 12,508 — 12,508 Total $ 167,584 $ 458,249 $ — $ 625,833

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: September 30, December 31, Research and development, including manufacturing and clinical expenditures $ 11,848 $ 7,667 Income taxes — 99 Payroll and payroll related 5,002 6,459 Professional fees and other 898 981 Total accrued expenses and other current liabilities $ 17,748 $ 15,206

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Stock Options Activity	The following table summarizes stock option activity: Number of Weighted Weighted Aggregate Outstanding at January 1, 2023 13,632,278 $ 18.48 7.7 $ 10,937 Granted 3,766,550 $ 4.49 Exercised — $ — Cancelled ( 392,509 ) $ 21.46 Outstanding at September 30, 2023 17,006,319 $ 15.31 7.4 $ 4,913 Vested and expected to vest at September 30, 2023 17,006,319 $ 15.31 7.4 $ 4,913 Vested and exercisable at September 30, 2023 10,208,053 $ 16.37 6.6 $ 4,874
Summary of Stock-based Compensation Expense by Award Type	Stock-based compensation expense by award type included within the unaudited condensed consolidated statements of operations and comprehensive loss was as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Stock options $ 11,295 $ 11,362 $ 34,592 $ 34,727 Restricted stock units 1,087 97 2,590 256 Performance-based stock units — — — — Employee stock purchase plan 1 45 89 90 Total stock-based compensation expense $ 12,383 $ 11,504 $ 37,271 $ 35,073
Schedule of Stock-based Compensation Expense	Stock-based compensation expense is classified as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Research and development expense $ 5,564 $ 5,370 $ 17,037 $ 16,390 General and administrative 6,819 6,134 20,234 18,683 Total stock-based compensation expense $ 12,383 $ 11,504 $ 37,271 $ 35,073
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Restricted Stock Units	Below is the activity related to restricted stock units for the nine months ended September 30, 2023. Number of Weighted Average Outstanding at January 1, 2023 161,750 $ 7.14 Granted 2,264,700 $ 4.59 Released ( 53,935 ) $ 7.14 Cancelled ( 34,998 ) $ 5.42 Unvested shares at September 30, 2023 2,337,517 $ 4.69
Performance-based Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Restricted Stock Units	The following table summarizes the activity related to performance-based restricted stock units for the nine months ended September 30, 2023. Number of Weighted Average Outstanding at January 1, 2023 724,970 $ 7.14 Granted — $ — Released — $ — Cancelled — $ — Unvested shares at September 30, 2023 724,970 $ 7.14

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Summary of Basic and Diluted Earnings Per Share	Basic and diluted earnings per share are calculated as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Net loss $ ( 33,142 ) $ ( 8,066 ) $ ( 96,792 ) $ ( 81,478 ) Weighted average common shares outstanding, basic and diluted 83,399,769 83,258,537 83,374,328 83,231,146 Net loss per share, basic and diluted $ ( 0.40 ) $ ( 0.10 ) $ ( 1.16 ) $ ( 0.98 )

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Summary of Assets and Liabilities Recorded on Balance Sheet	The following assets and liabilities are recorded on the Company’s consolidated balance sheet as of September 30, 2023. As of September 30, 2023 Right-of-use asset $ 1,970 Current lease liability 750 Non-current lease liability 1,835
Summary of Future Minimum Payments under Operating Leases	Future minimum payments under the 225 Lease, currently the Company’s only operating lease as of September 30, 2023 were as follows. As of September 30, 2023 Remainder of 2023 $ 201 2024 821 2025 838 2026 855 Total lease payments 2,715 Less amount representing implied interest ( 130 ) Total lease liability $ 2,585 Current portion of operating lease liabilities $ 750 Non-current portion of operating lease liabilities $ 1,835

Organization - Additional Infor

Organization - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Nov. 30, 2021
Organization [Line Items]
Cash and cash equivalents and marketable securities	$ 595.1
Number of shares issued	83,435,513	83,287,639
Sales Agreement | Jeffries
Organization [Line Items]
Commission percentage of aggregate gross proceeds from each sale of shares	3%
Number of shares issued	0
Sales Agreement | Jeffries | Maximum
Organization [Line Items]
Aggregate offering price			$ 200

Collaboration Agreement - Addit

Collaboration Agreement - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Disaggregation Of Revenue [Line Items]
Research and development expense	$ 28,181	$ 4,905	$ 79,198	$ 54,396
Prepaid expenses and other current assets	8,190		8,190		$ 14,213
Roche License Agreement
Disaggregation Of Revenue [Line Items]
Research and development credit adjustment	3,748	$ 14,572	12,625	$ 5,838
Prepaid expenses and other current assets	$ 3,748		$ 3,748

Marketable Securities - Additio

Marketable Securities - Additional Information (Details)	9 Months Ended
	Sep. 30, 2023 USD ($) Security	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-Sale [Abstract]
Number of held securities | Security	39
Debt securities in unrealized loss position	$ 325,000
Aggregate fair value	272,304,000
Marketable securities	457,240,000		$ 458,249,000
Securities maturing longer than one year	0
Sales and maturities of marketable securities	$ 527,664,000	$ 0

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 457,502	$ 458,933
Unrealized Gain	63
Unrealized Losses	(325)	(684)
Fair Value	457,240	458,249
US Treasury obligations
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	149,721	59,422
Unrealized Gain	8
Unrealized Losses	(104)	(304)
Fair Value	149,625	59,118
US Government agency securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	171,645	15,000
Unrealized Gain	55
Unrealized Losses	(106)	(59)
Fair Value	171,594	14,941
Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	84,281	310,433
Fair Value	84,281	310,433
Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	51,855	61,504
Unrealized Losses	(115)	(255)
Fair Value	$ 51,740	61,249
Asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost		12,574
Unrealized Losses		(66)
Fair Value		$ 12,508

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Cash equivalents
Marketable securities	$ 457,240	$ 458,249
Assets measured at fair value	594,879	625,833
Level 1
Cash equivalents
Assets measured at fair value	131,656	167,584
Level 2
Cash equivalents
Assets measured at fair value	463,223	458,249
US Treasury obligations
Cash equivalents
Marketable securities	149,625	59,118
US Treasury obligations | Level 2
Cash equivalents
Marketable securities	149,625	59,118
US Government agency securities
Cash equivalents
Marketable securities	171,594	14,941
US Government agency securities | Level 2
Cash equivalents
Marketable securities	171,594	14,941
Commercial paper
Cash equivalents
Cash equivalents	5,983
Marketable securities	84,281	310,433
Commercial paper | Level 2
Cash equivalents
Cash equivalents	5,983
Marketable securities	84,281	310,433
Corporate bonds
Cash equivalents
Marketable securities	51,740	61,249
Corporate bonds | Level 2
Cash equivalents
Marketable securities	51,740	61,249
Asset-backed securities
Cash equivalents
Marketable securities		12,508
Asset-backed securities | Level 2
Cash equivalents
Marketable securities		12,508
Money Market Funds
Cash equivalents
Cash equivalents	131,656	167,584
Money Market Funds | Level 1
Cash equivalents
Cash equivalents	$ 131,656	$ 167,584

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Research and development, including manufacturing and clinical expenditures	$ 11,848	$ 7,667
Income taxes		99
Payroll and payroll related	5,002	6,459
Professional fees and other	898	981
Total accrued expenses and other current liabilities	$ 17,748	$ 15,206

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - shares	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Equity [Abstract]
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	83,435,513	83,287,639
Common stock, shares outstanding	83,435,513	83,287,639
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.

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) $ in Thousands	1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended	27 Months Ended
	Jan. 31, 2023 shares	Oct. 31, 2020 shares	Sep. 30, 2023 USD ($) shares	Mar. 31, 2023 shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2023 USD ($) Installment shares	Sep. 30, 2022 USD ($) shares	Dec. 31, 2022 shares	Dec. 31, 2022 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted						3,766,550
Gross proceeds from issuance of common stock | $						$ 257	$ 140
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock under ESPP, shares			36,136	57,803	29,036
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of units granted						2,264,700	182,350
Number of units cancelled due to terminations						34,998
Aggregate grant date fair market value of restricted stock units granted | $						$ 10,384	$ 1,302
Number of installments | Installment						3
Unrecognized compensation expense | $			$ 8,408			$ 8,408
Remaining weighted average period for recognize compensation expense						2 years 2 months 12 days
Performance-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of units granted							742,070
Number of units cancelled due to terminations								17,100
Aggregate grant date fair market value of restricted stock units granted | $							$ 5,298
Performance based restricted stock units terms of award						The performance stock unit awards provide for a performance period from February 1, 2022 through January 31, 2025 to achieve up to six defined performance metrics. The percentage of each award eligible to vest will be determined based on the number of metrics achieved during the performance period and may range from 0% to 200%. The Company has not recognized any compensation expense through September 30, 2023, as the minimum performance criteria had not been deemed probable. The vesting of any eligible awards will occur in equal installments on January 31, 2025 and January 31, 2026.
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted			125,000		358,500	3,766,550	3,740,917
Aggregate grant date fair market value | $			$ 295		$ 2,188	$ 12,341	$ 19,217
Vesting service period						4 years
Award contractual term						10 years
Unrecognized compensation expense | $			$ 66,168			$ 66,168
Remaining weighted average period for recognize compensation expense						2 years 4 months 24 days
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares of common stock Outstanding		1%
Common stock, capital shares reserved for future issuance		1,187,000
Issuance of common stock under ESPP, shares			36,136		26,036	93,939	26,036
Gross proceeds from issuance of common stock | $			$ 92		$ 140	$ 257	$ 140
Employee Stock Purchase Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increased number of shares available under plan	832,876
2020 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increased number of shares available under plan	4,164,381								8,285,983
Percentage of shares of common stock Outstanding		5%
Common stock, capital shares reserved for future issuance			6,521,704			6,521,704
Minimum | Performance-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting percentage							0%
Maximum | Performance-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting percentage							200%
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 | 2020 Incentive Award Plan | From 2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant		5,982,266

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Restricted Stock Units (Details) - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, Outstanding	161,750
Number of shares, Granted	2,264,700	182,350
Number of shares, Released	(53,935)
Number of shares, Cancelled	(34,998)
Number of shares, Unvested	2,337,517		161,750
Weighted Average Grant Date Fair Value, Outstanding	$ 7.14
Weighted Average Grant Date Fair Value, Granted	4.59
Weighted Average Grant Date Fair Value, Released	7.14
Weighted Average Grant Date Fair Value, Cancelled	5.42
Weighted Average Grant Date Fair Value, Unvested	$ 4.69		$ 7.14
Performance-based Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares, Outstanding	724,970
Number of shares, Granted		742,070
Number of shares, Cancelled			(17,100)
Number of shares, Unvested	724,970		724,970
Weighted Average Grant Date Fair Value, Outstanding	$ 7.14
Weighted Average Grant Date Fair Value, Unvested	$ 7.14		$ 7.14

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Stock Options Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares, Outstanding | shares	13,632,278
Number of Shares, Granted | shares	3,766,550
Number of Shares, Cancelled | shares	(392,509)
Number of Shares, Outstanding | shares	17,006,319	13,632,278
Number of Shares, Vested and expected to vest | shares	17,006,319
Number of Shares, Vested and exercisable | shares	10,208,053
Weighted Average Exercise Price Per Share
Weighted Average Exercise Price Per Share, Outstanding | $ / shares	$ 18.48
Weighted Average Exercise Price Per Share, Granted | $ / shares	4.49
Weighted Average Exercise Price Per Share, Cancelled | $ / shares	21.46
Weighted Average Exercise Price Per Share, Outstanding | $ / shares	15.31	$ 18.48
Weighted Average Exercise Price Per Share, Vested and expected to vest | $ / shares	15.31
Weighted Average Exercise Price Per Share, Vested and exercisable | $ / shares	$ 16.37
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term (years), Outstanding	7 years 4 months 24 days	7 years 8 months 12 days
Weighted Average Remaining Contractual Term (years), Vested and expected to vest	7 years 4 months 24 days
Weighted Average Remaining Contractual Term (years), Vested and exercisable	6 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding | $	$ 4,913	$ 10,937
Aggregate Intrinsic Value, Vested and expected to vest | $	4,913
Aggregate Intrinsic Value, Vested and exercisable | $	$ 4,874

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock-based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 12,383	$ 11,504	$ 37,271	$ 35,073
Stock Options
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	11,295	11,362	34,592	34,727
Restricted Stock Units
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,087	97	2,590	256
Employee Stock Purchase Plan
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 1	$ 45	$ 89	$ 90

Stock-based Compensation - Stoc

Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 12,383	$ 11,504	$ 37,271	$ 35,073
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,564	5,370	17,037	16,390
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 6,819	$ 6,134	$ 20,234	$ 18,683

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net loss	$ (33,142)	$ (28,183)	$ (35,467)	$ (8,066)	$ (31,335)	$ (42,077)	$ (96,792)	$ (81,478)
Weighted average common shares outstanding, basic	83,399,769			83,258,537			83,374,328	83,231,146
Weighted average common shares outstanding, diluted	83,399,769			83,258,537			83,374,328	83,231,146
Net loss per share, basic	$ (0.40)			$ (0.10)			$ (1.16)	$ (0.98)
Net loss per share, diluted	$ (0.40)			$ (0.10)			$ (1.16)	$ (0.98)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from computation of diluted net income per share	17,006,319	13,490,691	17,006,319	13,490,691
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from computation of diluted net income per share	2,337,517	161,750	2,337,517	161,750
Performance-based Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from computation of diluted net income per share	724,970	724,970	724,970	724,970

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jan. 01, 2022
Lessor, Lease, Description [Line Items]
Operating lease right-of-use assets, net	$ 1,970		$ 1,970		$ 2,389
Operating lease liability	2,585		2,585
Operating lease costs	$ 162	$ 185	$ 485	$ 649
Office Space
Lessor, Lease, Description [Line Items]
Location of office space			Boston, Massachusetts at 225 Franklin Street
Lease commencement date			Jan. 01, 2022
Lease expiration date			Dec. 31, 2026
Lessor, Operating Lease, Existence of Option to Extend [true false]			false
Operating lease right-of-use assets, net						$ 2,938
Operating lease liability						$ 2,873

Leases - Summary of Assets and

Leases - Summary of Assets and Liabilities Recorded on Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Leases [Abstract]
Right-of-use asset	$ 1,970	$ 2,389
Current lease liability	750	721
Non-current lease liability	$ 1,835	$ 2,403

Leases - Future Minimum Payment

Leases - Future Minimum Payments under Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Leases [Abstract]
Remainder of 2023	$ 201
2024	821
2025	838
2026	855
Total lease payments	2,715
Less amount representing implied interest	(130)
Total lease liability	2,585
Current portion of operating lease liabilities	750	$ 721
Non-current portion of operating lease liabilities	$ 1,835	$ 2,403

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 221	$ (3,833)	$ 669	$ (3,713)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2023 USD ($)
Business Development Consulting Agreements | Maximum
Loss Contingencies [Line Items]
Success fee	$ 5,000,000

Benefit Plan - Additional Infor

Benefit Plan - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan recognized expense related to matching contributions	$ 105	$ 97	$ 642	$ 463
Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percentage			4%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - Consulting Agreement - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Entity Controlled by Director
Related Party Transaction [Line Items]
Annual retainer	$ 110,000		$ 110,000
Related Party | Director
Related Party Transaction [Line Items]
Related party transaction expense	0	$ 0	0	$ 1,000
Related Party | Entity Controlled by Director
Related Party Transaction [Line Items]
Related party transaction expense	$ 27,000	$ 27,000	$ 81,000	$ 81,000