Oncorus (ONCR) 10-Q 3 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 27, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Registrant Name	ONCORUS, INC.
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001671818
Entity Current Reporting Status	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity File Number	001-39575
Entity Address, Address Line One	50 Hampshire Street
Entity Address, Address Line Two	Suite 401
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Tax Identification Number	47-3779757
Entity Address, Postal Zip Code	02139
Entity Incorporation, State or Country Code	DE
City Area Code	(857)
Local Phone Number	320-6400
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		25,809,006
Security Exchange Name	NASDAQ
Trading Symbol	ONCR
Title of 12(b) Security	Common Stock, $0.0001 par value per share

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 145,603	$ 130,305
Prepaid expenses and other current assets	2,108	3,086
Total current assets	147,711	133,391
Property and equipment, net	14,093	4,173
Right-of-use asset	37,428	41,372
Restricted cash	2,877	2,877
Other assets	618	450
Total assets	202,727	182,263
Current liabilities:
Accounts payable	1,425	1,245
Accrued expenses	9,778	3,738
Lease liability - current portion	1,132	993
Other current liabilities	0	8
Total current liabilities	12,335	5,984
Lease liability - net of current portion	42,329	41,615
Other liabilities	221	0
Total liabilities	54,885	47,599
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock, $0.0001 par value; authorized — 10,000 shares at June 30, 2021 and December 31, 2020; issued and outstanding — no shares at June 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; authorized - 100,000 shares at June 30, 2021 and December 31, 2020; issued and outstanding - 25,741 and 22,599 shares at June 30, 2021 and December 31, 2020, respectively	3	2
Additional paid-in capital	322,583	264,487
Accumulated deficit	(174,744)	(129,825)
Total stockholders’ equity	147,842	134,664
Total liabilities and stockholders’ equity	$ 202,727	$ 182,263

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares Issued	25,758,000	22,599,000
Common Stock, Shares Outstanding	25,758,000	22,599,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses:
Research and development	$ 11,299	$ 6,927	$ 30,406	$ 19,560
General and administrative	5,440	1,973	14,550	6,032
Total operating expenses	16,739	8,900	44,956	25,592
Loss from operations	(16,739)	(8,900)	(44,956)	(25,592)
Other income (expense):
Change in fair value of Series B tranche rights		(10,631)		(11,256)
Other expense		(2)	(1)	(22)
Interest income	11	2	38	138
Total other income (expense), net	11	(10,631)	37	(11,140)
Net loss and comprehensive loss	(16,728)	(19,531)	(44,919)	(36,732)
Accretion of discount and dividends on redeemable convertible preferred stock		(2,848)		(8,298)
Net loss attributable to common stockholders	$ (16,728)	$ (22,379)	$ (44,919)	$ (45,030)
Net loss per share attributable to common stockholders—basic and diluted	$ (0.65)	$ (21.73)	$ (1.79)	$ (44.58)
Weighted-average number of common shares outstanding—basic and diluted	25,748	1,030	25,153	1,010

Consolidated Statements of Rede

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Series A-1 Redeemable Convertible Preferred Stock [Member]	Series B Redeemable Convertible Preferred Stock [Member]
Balance at Dec. 31, 2019					$ 63,494	$ 53,138
Balance (in shares) at Dec. 31, 2019					76,499,992	62,535,183
Balance (in shares) at Dec. 31, 2019		988,700
Balance at Dec. 31, 2019	$ (74,297)			$ (74,297)
Series A-1 and Series B preferred stock dividends and accretion	(5,450)		$ (624)	(4,826)	$ (3,140)	$ (2,310)
Stock-based compensation expense	619		619
Vesting of restricted common stock		14,026
Exercise of options to purchase common stock	5		5
Exercise of options to purchase common stock (Shares)		1,562
Net loss	(17,201)			(17,201)
Balance at Jun. 30, 2020					$ 66,634	$ 55,448
Balance (in shares) at Jun. 30, 2020					76,499,992	62,535,183
Balance (in shares) at Jun. 30, 2020		1,004,288
Balance at Jun. 30, 2020	(96,324)			(96,324)
Balance at Dec. 31, 2019					$ 63,494	$ 53,138
Balance (in shares) at Dec. 31, 2019					76,499,992	62,535,183
Balance (in shares) at Dec. 31, 2019		988,700
Balance at Dec. 31, 2019	(74,297)			(74,297)
Series A-1 and Series B preferred stock dividends and accretion	(8,298)
Proceeds from issuance of common stock, net of issuance costs
Net loss	(36,732)
Balance at Sep. 30, 2020					$ 68,220	$ 105,668
Balance (in shares) at Sep. 30, 2020					76,499,992	104,225,300
Balance (in shares) at Sep. 30, 2020		1,071,959
Balance at Sep. 30, 2020	(118,257)			(118,257)
Balance at Jun. 30, 2020					$ 66,634	$ 55,448
Balance (in shares) at Jun. 30, 2020					76,499,992	62,535,183
Balance (in shares) at Jun. 30, 2020		1,004,288
Balance at Jun. 30, 2020	(96,324)			(96,324)
Issuance of Series B preferred stock						$ 35,826
Issuance of Series B preferred stock (Shares)						41,690,117
Series A-1 and Series B preferred stock dividends and accretion	(2,848)		(446)	(2,402)	$ (1,586)	$ (1,262)
Settlement of Series B Tranche Rights						13,132
Stock-based compensation expense	340		340
Vesting of restricted common stock		5,171
Exercise of options to purchase common stock	106		106
Exercise of options to purchase common stock (Shares)		62,500
Net loss	(19,531)			(19,531)
Balance at Sep. 30, 2020					$ 68,220	$ 105,668
Balance (in shares) at Sep. 30, 2020					76,499,992	104,225,300
Balance (in shares) at Sep. 30, 2020		1,071,959
Balance at Sep. 30, 2020	(118,257)			(118,257)
Balance (in shares) at Dec. 31, 2020		22,599,048
Balance at Dec. 31, 2020	134,664	$ 2	264,487	(129,825)
Proceeds from issuance of common stock, net of issuance costs	52,983		52,983
Stock issued during the period (shares)		3,000,000
Stock-based compensation expense	2,828		2,828
Vesting of restricted common stock		10,341
Exercise of options to purchase common stock	347		347
Exercise of options to purchase common stock (Shares)		131,683
Net loss	(28,191)			(28,191)
Balance (in shares) at Jun. 30, 2021		25,741,072
Balance at Jun. 30, 2021	162,632	$ 3	320,645	(158,016)
Balance (in shares) at Dec. 31, 2020		22,599,048
Balance at Dec. 31, 2020	134,664	$ 2	264,487	(129,825)
Series A-1 and Series B preferred stock dividends and accretion
Proceeds from issuance of common stock, net of issuance costs	$ 52,983
Exercise of options to purchase common stock (Shares)	142,879,000
Net loss	$ (44,919)
Balance (in shares) at Sep. 30, 2021		25,758,059
Balance at Sep. 30, 2021	147,842	$ 3	322,583	(174,744)
Balance (in shares) at Jun. 30, 2021		25,741,072
Balance at Jun. 30, 2021	162,632	$ 3	320,645	(158,016)
Series A-1 and Series B preferred stock dividends and accretion
Stock-based compensation expense	1,889		1,889
Vesting of restricted common stock		5,171
Exercise of options to purchase common stock	49		49
Exercise of options to purchase common stock (Shares)		11,816
Net loss	(16,728)			(16,728)
Balance (in shares) at Sep. 30, 2021		25,758,059
Balance at Sep. 30, 2021	$ 147,842	$ 3	$ 322,583	$ (174,744)

Consolidated Statements of Re_2

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity (Parenthetical) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Statement of Stockholders' Equity [Abstract]
Payment of deferred offering costs	$ 4,017		$ 563

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities:
Net loss	$ (44,919)	$ (36,732)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,332	983
Stock-based compensation	4,717	959
Change in fair value of Series B tranche rights		11,256
Changes in:
Prepaid expenses and other assets	803	(840)
Operating lease right-of-use asset	2,208	354
Tenant Improvement Allowance Reimbursements	1,737
Accounts payable	109	103
Accrued expenses and other current liabilities	1,773	(885)
Operating lease liability	854	(825)
Net cash used in operating activities	(31,386)	(25,627)
Investing activities
Purchase of property and equipment	(6,695)	(1,014)
Net cash used in investing activities	(6,695)	(1,014)
Financing activities
Proceeds from issuance of Series B preferred stock and tranche liability		35,826
Proceeds from issuance of common stock, net of issuance costs	52,983
Proceeds from exercise of options to purchase of common stock	396	111
Payment of deferred offering costs		(563)
Net cash provided by financing activities	53,379	35,374
Increase in cash and cash equivalents	15,298	8,733
Cash, cash equivalents and restricted cash at beginning of period	133,182	45,286
Cash, cash equivalents and restricted cash at end of period	148,480	54,019
Supplemental disclosure of non-cash investing and financing activities
Purchase of property and equipment in accrued expenses and accounts payable	4,551
Accretion of discount and dividends on preferred stock		8,298
Deferred offering costs in accounts payable and accrued expenses		944
Settlement of Series B tranche rights		$ 13,132

Nature of the Business and Liqu

Nature of the Business and Liquidity	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Nature of the Business and Liquidity	1. Nature of the Business and Liquidity Oncorus, Inc. (the “Company”) is a clinical-stage biopharmaceutical company focused on developing next-generation viral immunotherapies to transform outcomes for cancer patients. Using its two platforms, the Company is developing a pipeline of intratumorally and intravenously administered product candidates designed to selectively attack and kill tumor cells. The Company’s operations to date have focused on organization and staffing, business planning, raising capital, acquiring and developing the Company’s technology, establishing the Company’s intellectual property portfolio, identifying potential product candidates and undertaking preclinical studies, commencing a clinical trial and manufacturing scale-up activities. The Company does not have any product candidates approved for sale and has not generated any revenue from product sales. The Company’s product candidates are subject to long development cycles and the Company may be unsuccessful in its efforts to develop, obtain regulatory approval for or market its product candidates. On September 25, 2020, the Company effected a 1-for-12.0874 reverse stock split of its issued and outstanding common stock and a proportional adjustment to the existing conversion ratios for the outstanding shares of Series A-1 redeemable convertible preferred stock (“Series A-1”) and Series B redeemable convertible preferred stock (“Series B”). Accordingly, all share and per share amounts for all periods presented in the accompanying unaudited interim condensed consolidated financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split, including reclassification of par, additional paid-in capital and accumulated deficit amounts as a result of the split adjustment. On October 6, 2020, the Company completed an initial public offering (“IPO”), in which the Company issued and sold 5,800,000 shares of its common stock at a public offering price of $ 15.00 per share. On October 14, 2020, the Company sold an additional 757,991 shares of common stock at $ 15.00 per share pursuant to the underwriters’ partial exercise of their option to purchase additional shares of common stock. The total gross proceeds from the IPO were $ 98.4 million and the Company raised $ 88.3 million in net proceeds after deducting underwriting discounts and commissions and offering expenses payable by the Company. Upon the closing of the IPO, all of the outstanding shares of convertible preferred stock automatically converted into 14,951,554 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of preferred stock outstanding. In February 2021, the Company completed a follow-on public offering of its common stock in which it sold 3,000,000 shares at an offering price of $ 19.00 per share, resulting in gross proceeds of $ 57.0 million and net proceeds of $ 53.0 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, possible failure of preclinical studies or clinical trials, the need to obtain marketing approval for its product candidates, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, the need to successfully commercialize and gain market acceptance of any of the Company’s products that are approved and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing, and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure, and extensive compliance-reporting capabilities. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The Company expects to continue to incur losses from operations for the foreseeable future and additional capital will be required to fund future operations. The Company expects that its cash and cash equivalents as of September 30, 2021 will be sufficient to fund its operating expenses and capital expenditure requirements through at least the next 12 months from the date these financial statements were issued.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements include all normal and recurring adjustments (which consist primarily of accruals and estimates that impact the financial statements) which are considered necessary to present fairly the Company’s financial position as of September 30, 2021, its results of operations for the three and nine months ended September 30, 2021 and 2020, its changes in redeemable preferred convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2020, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K (the "Annual Report") filed with the Securities and Exchange Commission (the “SEC”) on March 10, 2021. The condensed consolidated balance sheet data as of December 31, 2020 presented for comparative purposes was derived from the Company’s audited consolidated financial statements but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the operating results to be expected for the full year or for any other subsequent interim period. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2020, included in its Annual Report and, since that date, there have been no changes to the Company’s significant accounting policies. COVID-19 Pandemic With the ongoing COVID-19 global pandemic, the Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its employees and its business, including its preclinical studies, its ongoing clinical trial, and its regulatory filings. The Company has taken measures to secure its research and development activities, while work in its laboratories and facilities has been re-organized to reduce risks of COVID-19 transmission. Given the global impact and the other risks and uncertainties associated with the pandemic, the Company’s business, financial condition and results of operations could be materially adversely affected. The Company continues to closely monitor the COVID-19 pandemic and evolve its business continuity plans, clinical development plans and response strategy to mitigate any potential impact. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s financial statements. Going Concern At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern. Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements of the Company include the accounts of its wholly owned subsidiary, Oncorus Securities Corporation. All intercompany transactions have been eliminated in consolidation. The Company has one operating segment. 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 accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, the estimated fair value of the Company’s common stock and share-based awards utilized for stock-based compensation purposes, accrued expenses, and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity issuances as deferred offering costs until such equity issuances are consummated. After consummation of the equity issuance, these costs are recorded as a reduction in the capitalized amount associated with the equity issuance. Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company has all of its cash at one financial institution, that management believes to be of high credit quality, in amounts that exceed federally insured limits. Cash equivalents consist of money market funds that invest primarily in U.S. government-backed securities and treasuries. The Company is dependent upon a third-party contract manufacturer and third-party contract research organizations for the performance of portions of its testing for pre-clinical and clinical studies. The Company believes that its relationships with these organizations are satisfactory, and that alternative suppliers of these services are available in the event of the loss of one or more of these suppliers. Restricted Cash The Company maintains a balance in a segregated bank account in connection with a letter of credit for the benefit of the landlord in connection with an operating lease. As of September 30, 2021, restricted cash consisted of $ 2.9 million held for the benefit of the landlord. This amount has been classified as part of non-current assets on the Company's unaudited interim condensed consolidated balance sheets. The Company includes its restricted cash balance in the cash, cash equivalents and restricted cash reconciliation of operating, investing, and financing activities in the unaudited interim condensed consolidated statements of cash flows. The following table provides a reconciliation of cash, cash equivalents and restricted cash in the unaudited interim condensed consolidated balance sheets that sum to the total of the same such amounts shown in the unaudited interim condensed consolidated statements of cash flows (in thousands): September 30, 2021 2020 (in thousands) Cash and cash equivalents $ 145,603 $ 54,019 Restricted cash 2,877 — Total cash, cash equivalents and restricted cash shown in the unaudited interim consolidated statements of cash flows $ 148,480 $ 54,019 Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1 —Valuations based on quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 —Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly, such as quoted market prices, interest rates, and yield curves. Level 3 —Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent a valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s cash and cash equivalents, classified within Level 1, are valued using net asset value per share for the money market funds. The tranche rights granted to the Series B stockholders were classified within Level 3 of the fair value hierarchy because they were valued using significant inputs not observable in the market. The valuation of the tranche rights used assumptions the Company believed would be made by a market participant. The Company assessed these estimates on an ongoing basis as additional data impacting the assumptions was obtained. Refer to Note 6 for additional information regarding the valuation of the tranche rights. The Company believes that the carrying amounts of prepaid expenses, other current assets, accounts payable, and accrued expenses approximate their fair value due to the short-term nature of those instruments. Operating Leases During the quarter ended December 31, 2020, the Company early adopted ASC Topic 842, “Leases” (“ASC 842”) using the revised modified retrospective approach as of January 1, 2020. The unaudited interim condensed consolidated financial statements for the three and nine months ended September 30, 2020 have been retroactively adjusted to reflect the adoption of ASC 842, including retroactive adjustments to the unaudited interim condensed consolidated statement of cash flows and certain additional footnote disclosures as included herein. The adoption of ASC 842 had no material impact to the Company’s unaudited condensed consolidated statement of operations and comprehensive loss for the three and nine months ended September 30, 2020. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. The lease liability is measured at the present value of future lease payments, discounted using the discount rate as of the lease commencement date. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company recognizes a corresponding lease right of use (“ROU”) asset, initially measured as the amount of lease liability, adjusted for any initial lease costs or lease payments made before or at the commencement of the lease, and reduced by any lease incentives. The Company’s leases consist of only operating leases. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while certain variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis. Recently Issued Accounting Pronouncements There have been no recently issued accounting pronouncements other than those described in the Company’s audited financial statements as of and for the year ended December 31, 2020, and the notes thereto, which are included in the Annual Report.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis (in thousands): FAIR VALUE MEASUREMENTS LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds (included in cash and cash equivalents) $ 142,573 $ — $ — $ 142,573 $ 142,573 $ — $ — $ 142,573 FAIR VALUE MEASUREMENTS LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds (included in cash and cash equivalents) $ 126,056 $ — $ — $ 126,056 $ 126,056 $ — $ — $ 126,056

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	4. Leases The Company has an operating lease in Cambridge, Massachusetts for its corporate headquarters. The lease will expire in January 2024 and includes an optional extension for an additional three year period. The Company also has an operating lease for manufacturing and laboratory space in Andover, Massachusetts that expires in December 2036. The Company has two options to extend the term of the lease for a period of ten years each. As of September 30, 2021, the Company had not exercised its options to extend the lease term for either lease and it does not deem it reasonably certain that these options will be exercised. The Company agreed to provide the landlord with a $ 2.9 million letter of credit as support for its obligations under the Andover facility lease. The lease provides a lease incentive in the form of reimbursable leasehold improvements of approximately $ 13.2 million. As construction related to leasehold improvements is performed over the life of the lease, the right-of-use asset and lease liability will be adjusted on a prospective basis to reflect any payments relating to the lease incentive. In the nine months ended September 30, 2021, the Company capitalized $ 8.5 million of leasehold improvement costs, of which $ 1.7 million was reimbursed through the lease incentive. The lease payments include fixed base rent payments and variable rents for certain shared facility operating and other costs. During the three and nine months ended September 30, 2021, the lease liability and associated right-of-use asset for the Andover facility were reduced by $ 0.7 million due to changes in the timing of the expected commencement of base rent payments. During the three and nine months ended September 30, 2021 and 2020, the Company recognized total rent expense of $ 1.4 million, $ 0.3 million, $ 4.2 million, and $ 0.8 million, respectively, related to the leases described above. The amount of variable rent expense and rent for short-term leases for the three and nine months ended September 30, 2021 and 2020 was $ 0.5 million, $ 0.1 million, $ 1.3 million, and $ 0.4 million, respectively. Other supplemental information related to leases was as follows: NINE MONTHS ENDED 2021 2020 Weighted average remaining lease term 13.8 years 3.3 years Weighted average discount rate 8.5 % 12.0 % Cash paid for amounts included in the measurement of lease liabilities (in thousands) $ 1,143 $ 1,110 Maturities of operating lease liabilities were as follows as of September 30, 2021 (in thousands): Year Amount 2021 $ 634 2022 5,320 2023 5,600 2024 4,192 2025 4,317 Thereafter 56,956 Total lease payments 77,019 Less imputed interest ( 33,558 ) Total lease liabilities $ 43,461 Current portion 1,132 Long-term portion 42,329

Accrued Expenses and Other Long

Accrued Expenses and Other Long-Term Liabilities	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Accrued Expenses and Other Long-Term Liabilities	5. Accrued Expenses and Other Long-Term Liabilities Accrued expenses and other long-term liabilities consisted of the following (in thousands): SEPTEMBER 30, DECEMBER 31, Accrued research and development costs $ 2,520 $ 1,369 Accrued leasehold improvement costs 3,973 — Accrued long-term leasehold improvement costs 221 — Accrued compensation 2,369 1,661 Accrued professional fees 722 568 Miscellaneous accrued expenses 194 140 Total accrued expenses $ 9,999 $ 3,738 Accrued long-term leasehold improvement costs consist of retainage on construction invoices that the Company does not anticipate paying in the next 12 months based on timing of completion for the Andover facility buildout.

Series B Tranche Rights

Series B Tranche Rights	9 Months Ended
	Sep. 30, 2021
Warrants and Rights Note Disclosure [Abstract]
Series B Tranche Rights	6. Series B Tranche Rights Included in the terms of the purchase agreement for the Series B (“Series B Purchase Agreement”) entered into in August 2019 were Series B tranche rights (“Series B Tranche Rights”) granted to the purchasers of the Series B. The Series B Tranche Rights provided the holders with the right to purchase additional shares of Series B, in a second tranche, upon either the achievement by the Company of certain clinical development milestones for the Company’s primary clinical candidate, as set forth in the Series B Purchase Agreement, or upon the election of certain holders of the Series B prior to August 5, 2021. In the second tranche, the Company had the ability to sell up to 41,690,117 shares of Series B at $ 0.8597 per share. The Company reached the clinical development milestones set forth in the Series B Purchase Agreement in September 2020 and the Company sold 41,690,117 shares of Series B at $ 0.8597 per share, resulting in total gross proceeds to the Company of $ 35.8 million. At the time of issuance, the Series B Tranche Rights met the definition of a freestanding financial instrument, as the Series B Tranche Rights were both legally detachable and separately exercisable from the Series B. In addition, the Company determined at the time of issuance that the Series B Tranche Rights met the definition of a liability (or in some circumstances, an asset) because the Series B Tranche Rights (i) embodied an obligation to repurchase the Company’s equity shares and (ii) may have required the Company to settle the obligation by transferring assets. As a result, upon issuance, the respective Series B Tranche Rights were initially recorded at fair value and were subsequently re-measured at the end of each reporting period until settlement. Changes in the fair value were recognized as a component of other income (expense) in the consolidated statements of operations and comprehensive loss. At December 31, 2019 and at the end of each reporting period prior to settlement in September 2020, the estimated fair value of the Series B Tranche Rights was determined using a probability weighted present value model that considered the probability of triggering the Series B Tranche Rights through achievement of the clinical development milestones specified in the Series B Purchase Agreement. The Company converted the future values to their present values using a discount rate it considered to be appropriate for probability adjusted cash flows. The estimates were based, in part, on subjective assumptions. The Company remeasured the fair value of the tranche rights for a final time at the date of settlement on September 17, 2020. S ignificant assumptions for the Series B Tranche Rights valuation at December 31, 2019 and in 2020, prior to settlement, included an 85 % to 90 % probability of achieving the clinical development milestones and discount rates ranging from 0.2 % to 1.9 %. A rollforward of the Series B Tranche Rights liability for the nine months ended September 30, 2020 is as follows (in thousands): SERIES B Balance at December 31, 2019 $ 1,876 Change in fair value 11,256 Reclassification of Series B Tranche Rights upon settlement ( 13,132 ) Balance at September 30, 2020 $ —

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2021
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	7. Redeemable Convertible Preferred Stock Upon the closing of the IPO on October 6, 2020, all of the outstanding shares of Series A-1 and Series B automatically converted into an aggregate of 14,951,554 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of preferred stock outstanding. In connection with the closing of the IPO, the Company amended and restated its certificate of incorporation to provide for 10,000,000 shares of undesignated preferred stock with a par value of $ 0.0001 per share as part of its authorized capital. Issuance of Series B Redeemable Convertible Preferred Stock In August 2019, the Company authorized and agreed to sell 92,477,021 shares of Series B in two tranches. The first tranche closed on dates between August 5, 2019 and August 27, 2019. On those dates, the Company sold a total of 55,486,215 shares of Series B at $ 0.8597 per share, for gross proceeds to the Company of $ 47.7 million. In November 2019, the Company authorized and agreed to sell 11,748,279 additional shares of its Series B to new investors on the same terms and conditions as the previous sale of Series B. The first tranche of this sale occurred on November 27, 2019, in which the Company sold 7,048,968 shares of Series B for gross proceeds of $ 6.1 million. The Company paid $ 0.4 million of issuance costs related to these sales. In September 2020, the Company achieved the second tranche milestones related to the clinical development of its lead product candidate, ONCR-177. Upon achievement of the milestones, the Series B investors became obligated to purchase additional shares of Series B in a second tranche closing and the Company issued a total of 41,690,117 shares of Series B at $ 0.8597 per share, for aggregate proceeds to the Company of $ 35.8 million. A description of the rights and privileges of the Series B and Series A-1 prior to their conversion to common stock upon the IPO in October 2020 can be found in the Annual Report.

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2021
Statement of Stockholders' Equity [Abstract]
Common Stock	8. Common Stock Each share of the Company's common stock is entitled to one vote . The holders of shares of common stock are entitled to receive dividends, if and when declared by the Board of Directors. Prior to the IPO, the voting, dividend, and liquidation rights of the holders of common stock were subject to, and qualified by, the rights, powers, and preferences of the holders of Series B and Series A-1. Upon the closing of the IPO, the Company amended and restated its certificate of incorporation to provide for 100,000,000 shares designated as common stock with a par value of $ 0.0001 per share as part of its authorized capital. Restricted Stock The Company issued restricted stock to its founders and certain officers of the Company. In general, the shares of restricted stock vest over a four-year period, with 25 % of the shares vesting after one year, followed by monthly vesting over the remaining three years. A summary of non-vested restricted stock during the nine months ended September 30, 2021 is as follows: AMOUNT WEIGHTED-AVERAGE Balance at December 31, 2020 17,234 $ 1.57 Repurchases — — Issuances — — Vested ( 15,512 ) 1.57 Balance at September 30, 2021 1,722 Common Stock Warrants The Company issued warrants to purchase common stock (the “Common Stock Warrants”) in connection with a preferred stock financing in March 2016. The Common Stock Warrants allow for the holders to purchase 71,544 shares of common stock at $ 1.21 per share. As of September 30, 2021, all of the Common Stock Warrants were fully exercisable. The Common Stock Warrants expire in 2031. Reserved Shares The Company has reserved the following shares of common stock for the conversion or exercise of the following securities: SEPTEMBER 30, DECEMBER 31, Exercise of Common Stock Warrants 71,544 71,544 Exercise of options to purchase common stock 3,737,799 2,790,746 Vesting of restricted stock 1,722 17,234 Shares available for issuance under the 2020 Equity Incentive Plan 2,164,404 2,123,440 Total 5,975,469 5,002,964

Equity Incentive Plan

Equity Incentive Plan	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Equity Incentive Plan	9. Equity Incentive Plan The Company adopted the 2016 Equity Incentive Plan, as amended, (the “2016 Plan”) on March 31, 2016. The 2016 Plan provided for the granting of stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock awards to employees, directors and non-employees. All option awards were granted with an exercise price equal to or greater than the market price of the Company’s stock at the date of grant. Option awards generally vest over three to four years . Certain option awards provide for accelerated vesting if there is a change in control as defined in the 2016 Plan. The provisions of the 2016 Plan allow for early exercises for options that have not yet vested. Early exercises have historically been for a de minimis number of shares. On September 23, 2020, the Company adopted the 2020 Equity Incentive Plan (the “2020 Plan”), which became effective upon the execution of the underwriting agreement related to the IPO and serves as the successor to the 2016 Plan. The 2020 Plan authorizes the award of stock options, restricted stock awards, stock appreciation rights, restricted stock units, cash awards, performance awards and stock bonus awards. The number of shares reserved for issuance under the 2020 Plan will increase automatically on January 1 of each fiscal year, starting on January 1, 2021 and ending on and including January 1, 2030, by the number of shares equal to 5 % of the aggregate number of outstanding shares of common stock as of the immediately preceding December 31, or a lesser number of shares as may be determined by the board of directors (or an authorized committee thereof). On January 1, 2021, the number of shares reserved for issuance under the 2020 Plan automatically increased by 1,130,896 shares of common stock. At September 30, 2021, there were 2,164,404 shares of common stock available for issuance under the 2020 Plan. On September 23, 2020, the Company adopted the 2020 Employee Stock Purchase Plan (the "ESPP"), which became effective upon the execution of the underwriting agreement related to the IPO. The Company initially reserved 280,000 shares of common stock for sale under the ESPP. The aggregate number of shares reserved for sale under the ESPP will increase automatically on January 1st of each fiscal year starting on January 1, 2021 and ending on and including January 1, 2030, by the number of shares equal to the lesser of (a) 1% of the total number of shares of common stock outstanding on the last day of the fiscal year prior to the date of such automatic increase and (b) 560,000 shares, provided that prior to the date of any such increase, the board of directors may determine a lesser number of shares for such increase. In December 2020, the board of directors determined that there would be no automatic increase in the number of shares of common stock reserved under the ESPP on January 1, 2021. As of September 30, 2021, the Company had not commenced any offering periods under the ESPP. Total stock-based compensation (including both stock option awards and restricted stock awards) was classified as follows on the unaudited interim condensed consolidated statements of operations (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2021 2020 2021 2020 General and administrative $ 1,222 $ 172 $ 2,990 $ 512 Research and development 667 168 1,727 447 Total stock-based compensation $ 1,889 $ 340 $ 4,717 $ 959 Total stock-based compensation by award type was as follows (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2021 2020 2021 2020 Restricted stock $ 8 $ 7 $ 24 $ 24 Stock options 1,881 333 4,693 935 Total stock-based compensation $ 1,889 $ 340 $ 4,717 $ 959 In December 2020, the Company granted an employee an option to purchase 113,000 shares of the Company’s common stock with an exercise price per share equal to the fair value of the Company’s common stock on the date of grant. This grant is included in the outstanding options in the summary table below. The option grant includes three separate tranches (each tranche representing 33.33 % of the total grant) that will each vest four years from the date of grant. This option grant and its tranches are subject to accelerated vesting in the event that the Company achieves certain defined milestones related to the Company’s manufacturing efforts. As of September 30, 2021, the Company determined that the requisite service period of the award is four years and recorded $ 0.4 million of stock-based compensation expense for the nine months ended September 30, 2021. Accelerated vesting was not considered to be probable at September 30, 2021. A summary of option activity for the nine months ended September 30, 2021 is presented below: SHARES WEIGHTED WEIGHTED- AGGREGATE Outstanding at December 31, 2020 2,790,746 $ 8.13 Granted 1,178,709 $ 15.71 Exercised ( 142,879 ) $ 2.74 Canceled, expired or forfeited ( 88,777 ) $ 11.37 Outstanding at September 30, 2021 3,737,799 $ 10.65 8.41 $ 10,483 Vested and expected to vest at September 30, 2021 3,737,799 $ 10.65 8.41 $ 10,483 Exercisable at September 30, 2021 1,203,027 $ 3.62 7.19 $ 6,880 The weighted average grant date fair value per share of options granted to employees, directors and non-employee consultants during the nine months ended September 30, 2021 and 2020 was $ 11.25 and $ 5.34 , respectively. The total intrinsic value of options exercised was $ 1.8 million and $ 0.8 million for the nine months ended September 30, 2021 and 2020, respectively. Total unrecognized stock-based compensation expense related to options amounted to $ 21.4 million at September 30, 2021 and is expected to be recognized over a weighted-average period of 3.1 years. The total fair value of restricted shares vested was $ 0.02 million during each of the nine months ended September 30, 2021 and 2020.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies The Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses costs related to such legal proceedings as incurred.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	11. Net Loss Per Share The following securities that could potentially dilute basic net loss per share in the future were not included in the computation of diluted net loss per share for the periods presented, because to do so would have been antidilutive: NINE MONTHS ENDED 2021 2020 Series A-1 — 6,328,894 Series B — 8,622,625 Outstanding stock options 3,737,799 2,109,151 Restricted stock 1,722 22,405 Common stock warrants 71,544 71,544 Total 3,811,065 17,154,619

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events The Company has evaluated subsequent events from the balance sheet date through the date on which these financial statements were issued. Subsequent to the issuance of the financial statements, there were no events that occurred that required disclosure in, or revision to, the financial statements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements include all normal and recurring adjustments (which consist primarily of accruals and estimates that impact the financial statements) which are considered necessary to present fairly the Company’s financial position as of September 30, 2021, its results of operations for the three and nine months ended September 30, 2021 and 2020, its changes in redeemable preferred convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2020, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K (the "Annual Report") filed with the Securities and Exchange Commission (the “SEC”) on March 10, 2021. The condensed consolidated balance sheet data as of December 31, 2020 presented for comparative purposes was derived from the Company’s audited consolidated financial statements but does not include all disclosures required by GAAP. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the operating results to be expected for the full year or for any other subsequent interim period. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2020, included in its Annual Report and, since that date, there have been no changes to the Company’s significant accounting policies.
COVID-19 Pandemic	COVID-19 Pandemic With the ongoing COVID-19 global pandemic, the Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its employees and its business, including its preclinical studies, its ongoing clinical trial, and its regulatory filings. The Company has taken measures to secure its research and development activities, while work in its laboratories and facilities has been re-organized to reduce risks of COVID-19 transmission. Given the global impact and the other risks and uncertainties associated with the pandemic, the Company’s business, financial condition and results of operations could be materially adversely affected. The Company continues to closely monitor the COVID-19 pandemic and evolve its business continuity plans, clinical development plans and response strategy to mitigate any potential impact. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s financial statements.
Going Concern	Going Concern At each reporting period, the Company evaluates whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The Company is required to make certain additional disclosures if it concludes substantial doubt exists and it is not alleviated by the Company’s plans or when its plans alleviate substantial doubt about the Company’s ability to continue as a going concern.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements of the Company include the accounts of its wholly owned subsidiary, Oncorus Securities Corporation. All intercompany transactions have been eliminated in consolidation. The Company has one operating segment.
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 accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, the estimated fair value of the Company’s common stock and share-based awards utilized for stock-based compensation purposes, accrued expenses, and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity issuances as deferred offering costs until such equity issuances are consummated. After consummation of the equity issuance, these costs are recorded as a reduction in the capitalized amount associated with the equity issuance.
Concentration of Credit Risk and of Significant Suppliers	Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company has all of its cash at one financial institution, that management believes to be of high credit quality, in amounts that exceed federally insured limits. Cash equivalents consist of money market funds that invest primarily in U.S. government-backed securities and treasuries. The Company is dependent upon a third-party contract manufacturer and third-party contract research organizations for the performance of portions of its testing for pre-clinical and clinical studies. The Company believes that its relationships with these organizations are satisfactory, and that alternative suppliers of these services are available in the event of the loss of one or more of these suppliers.
Restricted Cash	Restricted Cash The Company maintains a balance in a segregated bank account in connection with a letter of credit for the benefit of the landlord in connection with an operating lease. As of September 30, 2021, restricted cash consisted of $ 2.9 million held for the benefit of the landlord. This amount has been classified as part of non-current assets on the Company's unaudited interim condensed consolidated balance sheets. The Company includes its restricted cash balance in the cash, cash equivalents and restricted cash reconciliation of operating, investing, and financing activities in the unaudited interim condensed consolidated statements of cash flows. The following table provides a reconciliation of cash, cash equivalents and restricted cash in the unaudited interim condensed consolidated balance sheets that sum to the total of the same such amounts shown in the unaudited interim condensed consolidated statements of cash flows (in thousands): September 30, 2021 2020 (in thousands) Cash and cash equivalents $ 145,603 $ 54,019 Restricted cash 2,877 — Total cash, cash equivalents and restricted cash shown in the unaudited interim consolidated statements of cash flows $ 148,480 $ 54,019
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1 —Valuations based on quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 —Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly, such as quoted market prices, interest rates, and yield curves. Level 3 —Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent a valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company’s cash and cash equivalents, classified within Level 1, are valued using net asset value per share for the money market funds. The tranche rights granted to the Series B stockholders were classified within Level 3 of the fair value hierarchy because they were valued using significant inputs not observable in the market. The valuation of the tranche rights used assumptions the Company believed would be made by a market participant. The Company assessed these estimates on an ongoing basis as additional data impacting the assumptions was obtained. Refer to Note 6 for additional information regarding the valuation of the tranche rights. The Company believes that the carrying amounts of prepaid expenses, other current assets, accounts payable, and accrued expenses approximate their fair value due to the short-term nature of those instruments.
Operating Leases	Operating Leases During the quarter ended December 31, 2020, the Company early adopted ASC Topic 842, “Leases” (“ASC 842”) using the revised modified retrospective approach as of January 1, 2020. The unaudited interim condensed consolidated financial statements for the three and nine months ended September 30, 2020 have been retroactively adjusted to reflect the adoption of ASC 842, including retroactive adjustments to the unaudited interim condensed consolidated statement of cash flows and certain additional footnote disclosures as included herein. The adoption of ASC 842 had no material impact to the Company’s unaudited condensed consolidated statement of operations and comprehensive loss for the three and nine months ended September 30, 2020. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. The lease liability is measured at the present value of future lease payments, discounted using the discount rate as of the lease commencement date. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. The Company recognizes a corresponding lease right of use (“ROU”) asset, initially measured as the amount of lease liability, adjusted for any initial lease costs or lease payments made before or at the commencement of the lease, and reduced by any lease incentives. The Company’s leases consist of only operating leases. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while certain variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements There have been no recently issued accounting pronouncements other than those described in the Company’s audited financial statements as of and for the year ended December 31, 2020, and the notes thereto, which are included in the Annual Report.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Summary Of Significant Accounting Policies [Abstract]
Summary of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash in the unaudited interim condensed consolidated balance sheets that sum to the total of the same such amounts shown in the unaudited interim condensed consolidated statements of cash flows (in thousands): September 30, 2021 2020 (in thousands) Cash and cash equivalents $ 145,603 $ 54,019 Restricted cash 2,877 — Total cash, cash equivalents and restricted cash shown in the unaudited interim consolidated statements of cash flows $ 148,480 $ 54,019

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis (in thousands): FAIR VALUE MEASUREMENTS LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds (included in cash and cash equivalents) $ 142,573 $ — $ — $ 142,573 $ 142,573 $ — $ — $ 142,573 FAIR VALUE MEASUREMENTS LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Money market funds (included in cash and cash equivalents) $ 126,056 $ — $ — $ 126,056 $ 126,056 $ — $ — $ 126,056

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Schedule of Other Supplemental Information Related to Leases	Other supplemental information related to leases was as follows: NINE MONTHS ENDED 2021 2020 Weighted average remaining lease term 13.8 years 3.3 years Weighted average discount rate 8.5 % 12.0 % Cash paid for amounts included in the measurement of lease liabilities (in thousands) $ 1,143 $ 1,110
Summary of Maturities of Operating Lease Liabilities	Maturities of operating lease liabilities were as follows as of September 30, 2021 (in thousands): Year Amount 2021 $ 634 2022 5,320 2023 5,600 2024 4,192 2025 4,317 Thereafter 56,956 Total lease payments 77,019 Less imputed interest ( 33,558 ) Total lease liabilities $ 43,461 Current portion 1,132 Long-term portion 42,329

Accrued Expenses and Other Lo_2

Accrued Expenses and Other Long-Term Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Summary of Accrued Expenses and Other Long-Term Liabilities	Accrued expenses and other long-term liabilities consisted of the following (in thousands): SEPTEMBER 30, DECEMBER 31, Accrued research and development costs $ 2,520 $ 1,369 Accrued leasehold improvement costs 3,973 — Accrued long-term leasehold improvement costs 221 — Accrued compensation 2,369 1,661 Accrued professional fees 722 568 Miscellaneous accrued expenses 194 140 Total accrued expenses $ 9,999 $ 3,738

Series B Tranche Rights (Tables

Series B Tranche Rights (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Series B Tranche Rights liability	A rollforward of the Series B Tranche Rights liability for the nine months ended September 30, 2020 is as follows (in thousands): SERIES B Balance at December 31, 2019 $ 1,876 Change in fair value 11,256 Reclassification of Series B Tranche Rights upon settlement ( 13,132 ) Balance at September 30, 2020 $ —

Common Stock (Tables)

Common Stock (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of Non-vested Restricted Stock Activity	A summary of non-vested restricted stock during the nine months ended September 30, 2021 is as follows: AMOUNT WEIGHTED-AVERAGE Balance at December 31, 2020 17,234 $ 1.57 Repurchases — — Issuances — — Vested ( 15,512 ) 1.57 Balance at September 30, 2021 1,722
Summary of Reserved Shares of Common Stock	The Company has reserved the following shares of common stock for the conversion or exercise of the following securities: SEPTEMBER 30, DECEMBER 31, Exercise of Common Stock Warrants 71,544 71,544 Exercise of options to purchase common stock 3,737,799 2,790,746 Vesting of restricted stock 1,722 17,234 Shares available for issuance under the 2020 Equity Incentive Plan 2,164,404 2,123,440 Total 5,975,469 5,002,964

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of Total Stock-based Compensation Including Both Stock Option Awards and Restricted Stock	Total stock-based compensation (including both stock option awards and restricted stock awards) was classified as follows on the unaudited interim condensed consolidated statements of operations (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2021 2020 2021 2020 General and administrative $ 1,222 $ 172 $ 2,990 $ 512 Research and development 667 168 1,727 447 Total stock-based compensation $ 1,889 $ 340 $ 4,717 $ 959 Total stock-based compensation by award type was as follows (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2021 2020 2021 2020 Restricted stock $ 8 $ 7 $ 24 $ 24 Stock options 1,881 333 4,693 935 Total stock-based compensation $ 1,889 $ 340 $ 4,717 $ 959
Summary of Option Activity	A summary of option activity for the nine months ended September 30, 2021 is presented below: SHARES WEIGHTED WEIGHTED- AGGREGATE Outstanding at December 31, 2020 2,790,746 $ 8.13 Granted 1,178,709 $ 15.71 Exercised ( 142,879 ) $ 2.74 Canceled, expired or forfeited ( 88,777 ) $ 11.37 Outstanding at September 30, 2021 3,737,799 $ 10.65 8.41 $ 10,483 Vested and expected to vest at September 30, 2021 3,737,799 $ 10.65 8.41 $ 10,483 Exercisable at September 30, 2021 1,203,027 $ 3.62 7.19 $ 6,880

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following securities that could potentially dilute basic net loss per share in the future were not included in the computation of diluted net loss per share for the periods presented, because to do so would have been antidilutive: NINE MONTHS ENDED 2021 2020 Series A-1 — 6,328,894 Series B — 8,622,625 Outstanding stock options 3,737,799 2,109,151 Restricted stock 1,722 22,405 Common stock warrants 71,544 71,544 Total 3,811,065 17,154,619

Nature of the Business and Li_2

Nature of the Business and Liquidity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Feb. 17, 2021	Oct. 14, 2020	Oct. 06, 2020	Sep. 25, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Accounting Policies [Line Items]
Reverse stock split description				1-for-12.0874
Stock Issued During Period, Shares, New Issues	3,000,000
Share issue price	$ 19
Gross proceeds from issuance initial public offering		$ 98,400
Proceeds from issuance of initial public offer		$ 88,300
Preferred stock, shares outstanding			0			0		0
Proceeds from issuance of common stock, gross	$ 57,000
Proceeds from issuance of common stock, net of issuance costs	$ 53,000				$ 52,983	$ 52,983
Common Stock [Member]
Accounting Policies [Line Items]
Stock Issued During Period, Shares, New Issues					3,000,000
Convertible preferred stock, shares			14,951,554
IPO [Member]
Accounting Policies [Line Items]
Stock Issued During Period, Shares, New Issues		757,991	5,800,000
Share issue price		$ 15	$ 15

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)Segment	Sep. 30, 2020USD ($)
Accounting Policies [Abstract]
Number of operating segments | Segment	1
Restricted cash | $	$ 2,877

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 145,603	$ 130,305	$ 54,019
Restricted cash	2,877
Cash, cash equivalents and restricted cash at end of period	$ 148,480	$ 133,182	$ 54,019	$ 45,286

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value On a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	$ 142,573	$ 126,056
Money market funds (included in cash and cash equivalents) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	142,573	126,056
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	142,573	126,056
Level 1 [Member] | Money market funds (included in cash and cash equivalents) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets	$ 142,573	$ 126,056

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessee Lease Description [Line Items]
Pledged letter of credit	$ 2,900		$ 2,900
Lease incentive related to reimbursable leasehold improvements	13,200		13,200
Leasehold improvement costs capitalized			8,500
Leasehold improvement costs reimbursed			1,700
Reduction in lease liability			854	$ (825)
Decrease in right-of-use asset			$ 2,208	354
Cambridge, Massachusetts [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, option to extend			The lease will expire in January 2024 and includes an optional extension for an additional three year period.
Andover, Massachusetts [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, option to extend			The Company has two options to extend the term of the lease for a period of ten years each.
Office Space [Member]
Lessee Lease Description [Line Items]
Reduction in lease liability	700		$ 700
Decrease in right-of-use asset	(700)		(700)
Rent expense for lease	1,400	$ 300	4,200	800
Lab Space [Member]
Lessee Lease Description [Line Items]
Rent expense for lease	1,400	300	4,200	800
Variable Rent Expense [Member]
Lessee Lease Description [Line Items]
Rent expense for lease	500	100	1,300	400
Short Term Lease Expense [Member]
Lessee Lease Description [Line Items]
Rent expense for lease	$ 500	$ 100	$ 1,300	$ 400

Leases - Summary of Other Suppl

Leases - Summary of Other Supplemental Information Related to Leases (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Weighted average remaining lease term	13 years 9 months 18 days	3 years 3 months 18 days
Weighted average discount rate	8.50%	12.00%
Cash paid for amounts included in the measurement of lease liabilities (in thousands)	$ 1,143	$ 1,110

Leases - Summary of Maturities

Leases - Summary of Maturities of Operating Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 634
2022	5,320
2023	5,600
2024	4,192
2025	4,317
Thereafter	56,956
Total lease payments	77,019
Less imputed interest	(33,558)
Total lease liabilities	43,461
Lease liability - current portion	1,132	$ 993
Lease liability - net of current portion	$ 42,329	$ 41,615

Accrued Expenses and Other Lo_3

Accrued Expenses and Other Long-Term Liabilities - Summary of Accrued Expenses and Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued research and development costs	$ 2,520	$ 1,369
Accrued leasehold improvement costs	3,973
Accrued long-term leasehold improvement costs	221
Accrued compensation	2,369	1,661
Accrued professional fees	722	568
Miscellaneous accrued expenses	194	140
Accrued Liabilities, Total	$ 9,999	$ 3,738

Series B Tranche Rights - Addit

Series B Tranche Rights - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Aug. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Proceeds from issuance of Series B preferred stock and tranche liability				$ 35,826
Maximum [Member] | Series B Tranche Rights [Member] | Measurement Input Probability Of Achievement [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
warrants and rights outstanding measurement					90.00%
Maximum [Member] | Series B Tranche Rights [Member] | Measurement Input, Discount Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
warrants and rights outstanding measurement					1.90%
Minimum [Member] | Series B Tranche Rights [Member] | Measurement Input Probability Of Achievement [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
warrants and rights outstanding measurement					85.00%
Minimum [Member] | Series B Tranche Rights [Member] | Measurement Input, Discount Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
warrants and rights outstanding measurement					0.20%
Series B Redeemable Convertible Preferred Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of Series B preferred stock (Shares)		41,690,117
Temporary Equity, Shares Authorized	41,690,117	41,690,117		41,690,117		92,477,021
Share price	$ 0.8597	$ 0.8597		$ 0.8597
Series B Redeemable Convertible Preferred Stock [Member] | Tranche Two [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Issuance of Series B preferred stock (Shares)	41,690,117
Share price	$ 0.8597	$ 0.8597		$ 0.8597
Proceeds from issuance of Series B preferred stock and tranche liability	$ 35,800

Series B Tranche Rights - Summa

Series B Tranche Rights - Summary of Series B Tranche Rights Liability (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Reclassification of Series B Tranche Rights upon settlement		$ 13,132
Series B Tranche Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		1,876
Change in fair value		11,256
Reclassification of Series B Tranche Rights upon settlement		(13,132)
Ending Balance

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock - Additional information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Nov. 27, 2019	Aug. 27, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Oct. 06, 2020	Nov. 30, 2019	Aug. 31, 2019
Redeemable Noncontrolling Interest [Line Items]
Preferred Stock, Shares Outstanding					0		0	0
Preferred Stock, Shares Authorized					10,000,000		10,000,000	10,000,000
Preferred Stock, Par or Stated Value Per Share					$ 0.0001		$ 0.0001	$ 0.0001
Proceeds from issuance of Series B preferred stock and tranche liability						$ 35,826
Series B Redeemable Convertible Preferred Stock [Member]
Redeemable Noncontrolling Interest [Line Items]
Temporary Equity, Shares Authorized			41,690,117	41,690,117		41,690,117				92,477,021
Temporary equity, additional shares authorized									11,748,279
Issuance of Series B preferred stock (Shares)				41,690,117
Share price			$ 0.8597	$ 0.8597		$ 0.8597
Series B Redeemable Convertible Preferred Stock [Member] | Tranche One [Member]
Redeemable Noncontrolling Interest [Line Items]
Issuance of Series B preferred stock (Shares)	7,048,968	55,486,215
Share price		$ 0.8597
Proceeds from issuance of Series B preferred stock and tranche liability	$ 6,100	$ 47,700
Payments of redeemable convertible preferred stock issuance costs	$ 400
Series B Redeemable Convertible Preferred Stock [Member] | Tranche Two [Member]
Redeemable Noncontrolling Interest [Line Items]
Issuance of Series B preferred stock (Shares)			41,690,117
Share price			$ 0.8597	$ 0.8597		$ 0.8597
Proceeds from issuance of Series B preferred stock and tranche liability			$ 35,800
Common Stock [Member]
Redeemable Noncontrolling Interest [Line Items]
Convertible preferred stock, shares								14,951,554

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Common stock, voting rights	Each share of the Company's common stock is entitled to one vote
Common Stock, Shares Authorized	100,000,000	100,000,000
Common stock, par or stated value per share	$ 0.0001	$ 0.0001
Warrants or rights, number of shares called	71,544	71,544
Common Stock Warrants [Member]
Warrants or rights, number of shares called	71,544
Warrants or rights, exercise price	$ 1.21
Restricted Stock [Member] | Founders [Member]
Share based payment award, award vesting period	4 years
Share-based payment award, award vesting percentage	25.00%

Common Stock - Summary of Non-V

Common Stock - Summary of Non-Vested Restricted Stock Activity (Detail) - Restricted Stock [Member]	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Balance at December 31, 2020	17,234
Vested	(15,512)
Balance at September 30, 2021	1,722
Balance at December 31, 2020 | $ / shares	$ 1.57
Vested | $ / shares	$ 1.57

Common Stock - Summary of Reser

Common Stock - Summary of Reserved Shares of Common Stock (Detail) - shares	Sep. 30, 2021	Dec. 31, 2020
Exercise of Common Stock Warrants	71,544	71,544
Exercise of options to purchase common stock	3,737,799	2,790,746
Shares available for issuance under 2020 Equity incentive plan	2,164,404	2,123,440
Total	5,975,469	5,002,964
Exercise of Options to Purchase Common Stock [Member]
Exercise of options to purchase common stock	3,737,799	2,790,746
Restricted Stock [Member]
Vesting of restricted stock	1,722	17,234

Equity Incentive Plan - Additio

Equity Incentive Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2021	Sep. 23, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for issuance under the 2020 Plan			2,123,440	2,164,404		2,164,404
Common stock reserved for future issuance			5,002,964	5,975,469		5,975,469
Share based payment awards options granted						1,178,709,000
Share-based payment arrangement, expense				$ 1,889	$ 340	$ 4,717	$ 959
Aggregate intrinsic value, Exercisable				6,880		$ 6,880
Unrecognized compensation expense related to stock options weighted average period						3 years 1 month 6 days
Fair value of restricted shares vested						$ 20	20
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment arrangement, expense				8	$ 7	$ 24	$ 24
2016 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value of options granted						$ 11.25	$ 5.34
Aggregate intrinsic value, options exercised						$ 1,800	$ 800
Unrecognized compensation expense related to stock options				$ 21,400		$ 21,400
2016 Plan [Member] | Restricted Stock [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award, award vesting period						3 years
2016 Plan [Member] | Restricted Stock [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award, award vesting period						4 years
2016 Plan [Member] | Performance Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award, award vesting period						4 years
Share based payment awards options granted			113,000
Share based payment award, requisite service period						4 years
Share-based payment arrangement, expense						$ 400
2016 Plan [Member] | Performance Share [Member] | Share-based payment arrangement, tranche one [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, award vesting percentage			33.33%
2016 Plan [Member] | Performance Share [Member] | Share-based payment arrangement, tranche two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, award vesting percentage			33.33%
2016 Plan [Member] | Performance Share [Member] | Share-based payment arrangement, tranche three [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award, award vesting percentage			33.33%
2020 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for issuance under the 2020 Plan				2,164,404		2,164,404
Share based payments shares increase decrease	1,130,896
2020 Plan [Member] | Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award description						The number of shares reserved for issuance under the 2020 Plan will increase automatically on January 1 of each fiscal year, starting on January 1, 2021 and ending on and including January 1, 2030, by the number of shares equal to 5% of the aggregate number of outstanding shares of common stock as of the immediately preceding December 31, or a lesser number of shares as may be determined by the board of directors (or an authorized committee thereof).
Share based payments shares increase/decrease						500.00%
Employee stock purchase plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment award description						The aggregate number of shares reserved for sale under the ESPP will increase automatically on January 1st of each fiscal year starting on January 1, 2021 and ending on and including January 1, 2030, by the number of shares equal to the lesser of (a) 1% of the total number of shares of common stock outstanding on the last day of the fiscal year prior to the date of such automatic increase and (b) 560,000 shares, provided that prior to the date of any such increase, the board of directors may determine a lesser number of shares for such increase.
Share based payments shares increase decrease	0	560,000
Common stock reserved for future issuance		280,000

Equity Incentive Plan - Summary

Equity Incentive Plan - Summary of Total Stock-based Compensation Including Both Stock Option Awards and Restricted Stock (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation expenses	$ 1,889	$ 340	$ 4,717	$ 959
Restricted Stock [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation expenses	8	7	24	24
Exercise of Options to Purchase Common Stock [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation expenses	1,881	333	4,693	935
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation expenses	1,222	172	2,990	512
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation expenses	$ 667	$ 168	$ 1,727	$ 447

Equity Incentive Plan - Summa_2

Equity Incentive Plan - Summary of Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Shares, Outstanding	2,790,746
Shares, Granted	1,178,709,000
Shares, Exercised	(142,879,000)
Shares, Canceled, expired or forfeited	(88,777,000)
Shares, Outstanding	3,737,799
Shares, Vested and expected to vest	3,737,799
Shares, Exercisable	1,203,027
Weighted average exercise price, Outstanding	$ 8.13
Weighted average exercise price, Granted	15.71
Weighted average exercise price, Exercised	2.74
Weighted average exercise price, Canceled, expired or forfeited	11.37
Weighted average exercise price, Outstanding	10.65
Weighted average exercise price, Vested and expected to vest	10.65
Weighted average exercise price, Exercisable	$ 3.62
Weighted- Average remaining contractual term (years), Outstanding	8 years 4 months 28 days
Weighted- Average remaining contractual term (years), Vested and expected to vest	8 years 4 months 28 days
Weighted- Average remaining contractual term (years), Exercisable	7 years 2 months 8 days
Aggregate intrinsic value, Outstanding	$ 10,483
Aggregate intrinsic value, Vested and expected to vest	10,483
Aggregate intrinsic value, Exercisable	$ 6,880

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	3,811,065	17,154,619
Series A-1 [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	0	6,328,894
Series B [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	0	8,622,625
Outstanding Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	3,737,799	2,109,151
Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	1,722	22,405
Common stock warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities dilute basic net loss per share	71,544	71,544