SQZ Biotechnologies (SQZB) 10-K 16 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 11, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	SQZ BIOTECHNOLOGIES COMPANY
Entity Central Index Key	0001604477
Entity Incorporation, State or Country Code	DE
Current Fiscal Year End Date	--12-31
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	SQZ
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity File Number	001-39662
Entity Tax Identification Number	46-2431115
Entity Address, Address Line One	200 Arsenal Yards Blvd
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	617
Local Phone Number	758-8672
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Document Annual Report	true
Document Transition Report	false
Entity Public Float			$ 348.8
Entity Common Stock, Shares Outstanding		28,147,555
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s Definitive Proxy Statement relating to the Registrant’s 2022 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission within 120 days of the end of the Registrant’s fiscal year ended December 31, 2021 are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 143,513	$ 170,357
Accounts receivable	3,000	1,892
Prepaid expenses and other current assets	4,122	4,582
Total current assets	150,635	176,831
Property and equipment, net	3,046	3,645
Restricted cash	2,305	2,305
Deferred offering costs	323
Operating lease right-of-use assets	69,843	48,360
Total assets	226,152	231,141
Current liabilities:
Accounts payable	3,971	3,708
Accrued expenses	6,810	7,358
Current portion of deferred revenue	12,507	25,917
Current portion of operating lease liabilities	9,936	8,210
Total current liabilities	33,224	45,193
Deferred revenue, net of current portion	9,196	19,659
Operating lease liabilities, net of current portion	59,756	38,885
Other liabilities		205
Total liabilities	102,176	103,942
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2021 and 2020, respectively; No shares issued or outstanding.
Common stock, $0.001 par value; 200,000,000 shares authorized at December 31, 2021 and 2020, respectively; 28,133,368 and 24,786,424 shares issued and outstanding at December 31, 2021 and 2020, respectively.	28	25
Additional paid-in capital	319,458	253,943
Accumulated deficit	(195,510)	(126,769)
Total stockholders' equity	123,976	127,199
Total liabilities, and stockholders' equity	$ 226,152	$ 231,141

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
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	200,000,000	200,000,000
Common stock, shares issued	28,133,368	24,786,424
Common stock, shares outstanding	28,133,368	24,786,424

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Total revenue	$ 27,098	$ 20,998
Revenue, Product and Service [Extensible Enumeration]	Collaboration [Member]	Collaboration [Member]
Operating expenses:
Research and development	$ 70,148	$ 51,545
General and administrative	25,719	20,511
Total operating expenses	95,867	72,056
Loss from operations	(68,769)	(51,058)
Other income (expense):
Interest income	36	550
Other income (expense), net	(8)	(13)
Total other income, net	28	537
Net loss	$ (68,741)	$ (50,521)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.49)	$ (9.35)
Weighted-average common shares outstanding, basic and diluted	27,578,844	5,401,895
Comprehensive loss:
Net loss	$ (68,741)	$ (50,521)
Other comprehensive income (loss):
Reclassification adjustment for gains included in net loss, net of tax		(30)
Comprehensive loss	$ (68,741)	$ (50,551)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Initial Public Offering [Member]	Public Offering [Member]	Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]Initial Public Offering [Member]	Common Stock [Member]Public Offering [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Initial Public Offering [Member]	Additional Paid-in Capital [Member]Public Offering [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2019	$ (73,515)				$ 2			$ 2,701			$ 30	$ (76,248)
Beginning balance, convertible preferred stock (Shares) at Dec. 31, 2019				13,869,027
Beginning balance, convertible preferred stock at Dec. 31, 2019				$ 132,109
Beginning balance (Shares) at Dec. 31, 2019					1,737,388
Issuance of Series D convertible preferred stock, net of issuance costs				$ 42,248
Issuance of Series D convertible preferred stock, net of issuance costs (Shares)				3,035,192
Conversion of convertible preferred stock into common stock	174,351			$ (174,357)	$ 18			174,333
Conversion of convertible preferred stock into common stock (Shares)				(16,904,219)	17,800,084
Issuance of common stock		$ 72,878				$ 5			$ 72,873
Issuance of common stock (Shares)					10,378	5,073,529
Issuance of common stock upon exercise of stock options	434							434
Issuance of common stock upon exercise of stock options (Shares)					164,945
Stock-based compensation expense	3,602							3,602
Net loss	(50,521)											(50,521)
Other comprehensive income	(30)										$ (30)
Ending balance at Dec. 31, 2020	127,199				$ 25			253,943				(126,769)
Ending balance (Shares) at Dec. 31, 2020					24,786,324
Issuance of common stock			$ 55,602				$ 3			$ 55,599
Issuance of common stock (Shares)							3,000,000
Issuance of common stock upon exercise of stock options	$ 1,307							1,307
Issuance of common stock upon exercise of stock options (Shares)	333,417				333,417
Issuance of common stock under employee stock purchase plan	$ 104							104
Issuance of common stock under employee stock purchase plan (Shares)					13,627
Stock-based compensation expense	8,505							8,505
Net loss	(68,741)											(68,741)
Ending balance at Dec. 31, 2021	$ 123,976				$ 28			$ 319,458				$ (195,510)
Ending balance (Shares) at Dec. 31, 2021					28,133,368

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Payment of issuance costs	$ 798
Public Offering [Member]
Payment of issuance costs	$ 798

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (68,741)	$ (50,521)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	1,208	1,342
Amortization of operating lease right-of-use assets	9,822	9,601
Stock-based compensation expense	8,505	3,602
Accretion of discounts on marketable securities		(5)
Loss on disposal of property and equipment	7
Loss on termination of operating lease		108
Changes in operating assets and liabilities:
Accounts receivable	(1,108)	(18)
Prepaid expenses and other current assets	460	(2,920)
Accounts payable	1,074	100
Accrued expenses	(283)	246
Deferred revenue	(23,873)	4,748
Deferred offering costs	(323)
Operating lease liabilities	(8,710)	(8,899)
Other liabilities	(175)	(535)
Net cash used in operating activities	(82,137)	(43,151)
Cash flows from investing activities:
Purchases of property and equipment	(613)	(1,177)
Sales and maturities of marketable securities		59,000
Net cash (used in) provided by investing activities	(613)	57,823
Cash flows from financing activities:
Payment of initial public offering costs	(1,106)	(1,515)
Proceeds from issuance of convertible preferred stock, net of issuance costs paid in the period		42,248
Payment of issuance costs	(798)
Proceeds from issuance of common stock under employee stock purchase plan	103
Proceeds from exercise of stock options	1,307	434
Net cash provided by financing activities	55,906	116,416
Net (decrease) increase in cash, cash equivalents and restricted cash	(26,844)	131,088
Cash, cash equivalents and restricted cash at beginning of period	172,662	41,574
Cash, cash equivalents and restricted cash at end of period	145,818	172,662
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock		174,351
Lease assets obtained in exchange for operating lease liabilities	31,307	17,049
Initial public offering costs included in accounts payable and accrued expenses at end of period		1,106
Convertible Preferred Stock [Member]
Cash flows from financing activities:
Payment of issuance costs		(245)
Initial Public Offering [Member]
Cash flows from financing activities:
Proceeds from public offering of common stock, net of commissions and underwriting discounts		75,494
Follow On Public Offering [Member]
Cash flows from financing activities:
Proceeds from public offering of common stock, net of commissions and underwriting discounts	$ 56,400
Common Stock [Member] | Initial Public Offering [Member]
Cash flows from financing activities:
Payment of issuance costs		$ (2,621)

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation SQZ Biotechnologies Company (the “Company”) is a clinical-stage biotechnology company developing cell therapies for patients with cancer, infectious diseases and other serious conditions. The Company uses its proprietary technology, Cell Squeeze, to physically squeeze cells through a microfluidic chip, temporarily opening the cell membrane and enabling biologic material of interest, or cargo, to diffuse into the cell. The Company is using Cell Squeeze to create multiple cell therapy platforms focused on directing specific immune responses. The Company was incorporated in March 2013 under the laws of the State of Delaware. The Company is subject to a number of risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, the ability to obtain additional financing, protection of proprietary technology, dependence on key personnel, the ability to attract and retain qualified employees, compliance with government regulations, the impact of the COVID-19 coronavirus, and the clinical and commercial success of its product candidates. 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. On October 23, 2020, the Company effected a 1.0530 -for-one stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s Preferred Stock. Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this stock split and adjustment of the Preferred Stock conversion ratios. On November 3, 2020, the Company completed its initial public offering (“IPO”) pursuant to which it issued and sold 4,411,765 shares of its common stock. On November 12, 2020, the Company issued and sold an additional 661,764 shares of its common stock pursuant to the full exercise of the underwriters’ option to purchase additional shares. The aggregate proceeds, net of commissions and underwriting discounts received by the Company from the IPO were approximately $ 75.5 million, before deducting offering costs payable by the Company, which were $ 2.6 million. Upon the closing of the IPO, all of the shares of the Company’s convertible preferred stock then outstanding were automatically converted into 17,800,084 shares of common stock. On February 17, 2021, the Company completed a follow-on public offering (the "Follow-On Offering") pursuant to which it issued and sold 3,000,000 shares of its common stock. The aggregate proceeds, net of commissions and underwriting discounts received by the Company from the Follow-On Offering were approximately $ 56.4 million, before deducting offering costs payable by the Company, which were $ 0.8 million. The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Through December 31, 2021, the Company has funded its operations primarily with proceeds from sales of convertible preferred stock, payments received in connection with collaboration agreements, proceeds from borrowings under a convertible promissory note, which converted into shares of convertible preferred stock, and more recently the proceeds from its IPO and the Follow-On Offering. The Company has incurred recurring losses since inception, including a net loss of $ 68.7 million for the year ended December 31, 2021. As of December 31, 2021, the Company had an accumulated deficit of $ 195.5 million. The Company expects to continue to generate operating losses in the foreseeable future. As of March 16, 2022, the issuance date of the annual consolidated financial statements for the year ended December 31, 2021, the Company expected that its cash and cash equivalents, would be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance date of the annual consolidated financial statements. The Company may seek additional funding through private or public equity financings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs, product expansion or commercialization efforts, or the Company may be unable to continue operations. Although management may pursue these financing plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. Impact of the COVID-19 Coronavirus In December 2019, a novel strain of coronavirus, which causes the disease known as COVID-19, was reported to have surfaced in Wuhan, China. Since then, COVID-19 coronavirus has spread globally. In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic and the U.S. government-imposed travel restrictions on travel between the United States, Europe and certain other countries. The outbreak and government measures taken in response have had a significant impact, both direct and indirect, on hospitals, businesses and commerce, as worker shortages have occurred, supply chains have been disrupted, and facilities and production have been suspended. The future progression of the pandemic and its effects on the Company’s business and operations are uncertain. The COVID-19 pandemic has impacted and may continue to impact personnel at third-party manufacturing facilities or the availability or cost of materials, which would disrupt the Company’s supply chain. It also has affected and may continue to affect the Company’s ability to enroll patients in and timely complete its ongoing clinical trials of SQZ-PBMC-HPV, SQZ-AAC-HPV and SQZ-eAPC-HPV and delay the initiation of future clinical trials, disrupt regulatory activities or have other adverse effects on its business and operations. The Company is monitoring the potential impact of the COVID-19 pandemic on its business and financial statements. To date, the Company has not incurred impairment losses in the carrying values of its assets as a result of the pandemic and it is not aware of any specific related event or circumstance that would require it to revise its estimates reflected in these consolidated annual or interim financial statements. The extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations, financial condition and liquidity, including planned and future clinical trials and research and development costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19, the actions taken to contain or treat it, and the duration and intensity of the related effects. Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, SQZ Biotechnologies Security Corporation and SQZ Biotech HK Limited. All intercompany accounts and transactions have been eliminated in consolidation.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual of research and development expenses, the valuation of common stock and the valuation of stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions. Concentrations of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of accounts receivable and cash and cash equivalents. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. As of December 31, 2021 and 2020, all of the Company’s accounts receivable were related to its collaboration agreements with Roche (see Note 11). The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and to process its product candidates for its development programs. These programs could be adversely affected by a significant interruption in the manufacturing process or supply chain. Cash Equivalents The Company considers all highly liquid investments in marketable securities with original maturities of three months or fewer at the date of purchase to be cash equivalents. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering in stockholder’s equity as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss. Deferred offering costs as of December 31, 2021 are expenses directly related to the Form S-3 filed with the SEC on November 12, 2021 and declared effective on November 18, 2021 (the "Shelf Registration"). These costs consist of legal, accounting, printing and filing fees that the Company has capitalized, including fees incurred by the independent registered public accounting firm directly related to the Shelf Registration. Deferred costs associated with the Shelf Registration are reclassified to additional paid in capital on a pro-rata basis when the Company completes offerings under the Shelf Registration, with any remaining deferred offering costs to be charged to the results of operations if the planned offering is abandoned, or at the end of the three-year life of the Shelf Registration. The Company had $ 0.3 million and $ 0 of deferred offering costs as of December 31, 2021 and 2020 , respectively. Accounts Receivable Allowance Accounts receivable are presented net of an allowance for doubtful accounts, which is an estimate of amounts that may not be collectible. The Company performs ongoing evaluations of its accounts receivable and, if necessary, provides an allowance for doubtful accounts and expected losses. The Company writes off accounts receivable against the allowance when it determines a balance is uncollectible and no longer actively pursues collection of the receivable. As of December 31, 2021 and 2020 , the Company had no allowance for doubtful accounts. During the years ended December 31, 2021 and 2020 the Company did no t record any provisions for doubtful accounts and did no t write off any accounts receivable balances. Restricted Cash As of December 31, 2021 and 2020 , the Company maintained letters of credit totaling $ 2.3 million for the benefit of the landlord of its leased properties. The Company was required to maintain separate cash balances of $ 2.3 million to secure the letters of credit. The Company classified these separate cash balances of $ 2.3 million as restricted cash (non-current) in the consolidated balance sheets as of December 31, 2021 and 2020 based on the release dates of the restrictions on this cash. As of December 31, 2021 and 2020, the cash, cash equivalents and restricted cash of $ 145.8 million and $ 172.7 million, respectively, presented in the consolidated statements of cash flows included cash and cash equivalents of $ 143.5 million and $ 170.4 million, respectively, and restricted cash of $ 2.3 million for each of the years ended December 31, 2021 and 2020 . Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows: ESTIMATED USEFUL LIFE Machinery and equipment 3 to 5 years Furniture and fixtures 7 years Leasehold improvements Shorter of term of lease or 7 years Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated in accordance with the above guidelines once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are expensed as incurred. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. The Company continually evaluates long-lived assets for potential impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares the carrying values of the asset group to the expected future undiscounted cash flows that the asset group is expected to generate from the use and eventual disposition of the long-lived asset group. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. If such asset group is considered to be impaired, the impairment loss to be recognized would be based on the excess of the carrying value of the impaired asset group over its fair value. The Company did no t recognize any impairment losses on long-lived assets during the years ended December 31, 2021 and 2020 . Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. 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—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The fair value of the Company’s cash equivalents are determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts receivable, unbilled receivables, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. Leases The Company accounts for leases under Accounting Standards Codification (“ASC”) 842, Leases (“ASC 842”). The Company has operating leases for office space as well as a contract for manufacturing under which the Company has a dedicated suite. The Company may enter into similar arrangements in the future. Under ASC 842, the Company determines whether such arrangements contain a lease at the inception of a contract by assessing whether there is an identified asset and whether a contract conveys the right to control the use of the identified asset in exchange for consideration and the right to obtain the economic benefits from the use of the identified asset. Upon commencement of an identified lease, the Company records a right-of-use asset, which represents the Company’s right to use the underlying asset for the lease term, and records a lease liability, which represents the Company’s obligation to make lease payments arising from the lease. Right-of-use assets and lease liabilities are recognized at commencement date of the lease based on the present value of the future minimum lease payments over the lease term. Lease payments are discounted at the lease commencement date using the rate implicit in the lease, unless that rate is not readily determinable. As most of the Company’s leases do not provide an implicit rate, the Company determines an incremental borrowing rate, which represents an internally estimated rate that would be incurred by the Company to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment, based on the information available at the commencement date of each lease in determining the present value of the future minimum lease payments. The determination of the incremental borrowing rate is a significant management judgment, which is based on an analysis that includes the credit rating of the Company, geographical risk, and U.S. Treasury and corporate bond yields. After lease commencement and the establishment of a right-of-use asset and operating lease liability, lease expense is recorded on a straight-line basis over the lease term. As permitted by ASC 842, leases with an initial term of 12 months or fewer are not recorded in the consolidated balance sheets. The Company often enters into contracts that contain both lease and non-lease components. Non-lease components include real estate taxes, insurance, maintenance, utilities and other operating costs. The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single component. Variable costs, such as utilities or maintenance costs, are not included in the measurement of right-of-use assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs. The Company’s lease terms often include renewal options. The amounts determined for the Company’s right-of-use assets and lease liabilities generally do not assume that any renewal options or any early-termination provisions, if any, are exercised, unless it is reasonably certain that the Company will exercise such options. Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company is developing methods of engineering cell function and therapies for the treatment of patients across a range of indications. The Company has determined that its chief operating decision maker is its Chief Executive Officer. The Company’s chief operating decision maker reviews the Company’s financial information on a consolidated basis for purposes of allocating resources and assessing financial performance. All of the Company’s tangible assets are held in the United States, and all of the Company’s collaboration revenue is derived from its collaboration partner headquartered in Switzerland. Revenue Recognition for License and Collaboration Arrangements Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract, determines which goods or services are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when, or as, that performance obligation is satisfied. The Company enters into licensing arrangements that are within the scope of ASC 606, under which it may exclusively license to third parties rights to research, develop, manufacture and commercialize its product candidates. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and sales milestone payments; and royalties on net sales of licensed products. The payment terms under the Company’s existing licensing arrangements are 60 days. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its arrangements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the assessment of the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when, or as, the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the standalone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above. The Company also uses judgment to determine whether milestone payments or other variable consideration, except for royalties and sales-based milestones, should be included in the transaction price, as described below. The transaction price is allocated to each performance obligation based on the relative standalone selling price of each performance obligation in the contract, and the Company recognizes revenue based on those amounts when, or as, the performance obligations under the contract are satisfied. The standalone selling price is the price at which an entity would sell a promised good or service separately to a customer. Management estimates the standalone selling price of each of the identified performance obligations in the Company’s customer contracts, maximizing the use of observable inputs. Because the Company has not sold the same goods or services in its contracts separately to any customers on a standalone basis and there are no similar observable transactions in the marketplace, the Company estimates the standalone selling price of each performance obligation in its customer arrangements based on its estimate of costs to be incurred to fulfil its obligations associated with the performance, plus a reasonable margin. The Company has determined that its only contract liability under ASC 606 is deferred revenue. Amounts received prior to revenue recognition are recorded as deferred revenue in the consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion, in the consolidated balance sheets. Exclusive Licenses If the license to the Company’s intellectual property is determined to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes revenue from nonrefundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. In assessing whether a promise or performance obligation is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a promise for its intended purpose without the receipt of the remaining promises, whether the value of the promise is dependent on the unsatisfied promises, whether there are other vendors that could provide the remaining promises, and whether it is separately identifiable from the remaining promises. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of progress and related revenue recognition. The measure of progress, and the resulting periods over which revenue should be recognized, are subject to estimates by management and may change over the course of the research, development and licensing arrangement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Under the Company’s existing license and collaboration agreements, the Company has concluded that the transfer of control to the customer occurs over the time period that the research and development services are to be provided by the Company, and this cost-to-cost method is, in management’s judgment, the best measure of progress towards satisfying the performance obligation. Research and Development Services The promises under the Company’s license and collaboration arrangements often include research and development services to be performed by the Company on behalf of the partner. Payments or reimbursements resulting from the Company’s research and development efforts are estimated at the outset of the arrangement and considered part of the transaction price that is subsequently recognized as revenue because the Company is the principal in the arrangement for such efforts. Customer Options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the Company evaluates the customer options to determine if they are material rights at the outset of each arrangement. Options to acquire additional goods or services for free or at a discount are deemed to be material rights. If the goods and services underlying the customer options are not determined to be material rights, these customer options are not considered to be performance obligations in the arrangement because they are contingent upon exercise of the option. If the customer options are determined to be a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the probability that the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone Payments At the inception of each arrangement that includes potential research, development or regulatory milestone payments, the Company evaluates whether the milestones are considered likely to be met and estimates the amount to be considered for inclusion in the transaction price using the most-likely-amount method. If it is probable that a significant reversal in the amount of cumulative revenue recognized would not occur, the associated milestone payment value is included in the transaction price. For milestone payments due upon events that are not within the control of the Company or the licensee, such as regulatory approvals, the Company is not able to assert that it is likely that the regulatory approval will be granted and that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur until those approvals are received. In making this assessment, the Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the particular milestone. There is considerable judgment involved in determining whether it is probable that a significant reversal in the amount of cumulative revenue recognized would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price of the arrangement. Any such adjustments are recorded on a cumulative catch-up basis, which would affect the amounts of revenue and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments due upon first commercial sales or based on a level of sales, that are the result of a customer-vendor relationship and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) the occurrence of the related sales or (ii) the date upon which the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue from any of its licensing arrangements. Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, laboratory supplies, depreciation, manufacturing expenses and external costs of vendors engaged to conduct preclinical development activities and clinical trials, as well as the costs of licensing technology and costs related to collaboration arrangements. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered. Research and Manufacturing Contract Costs and Accruals The Company has entered into various research, development and manufacturing contracts with research institutions and other companies in the United States. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research, development and manufacturing costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research, development and manufacturing activities, invoicing to date under the contracts, communication from the research institutions and other companies of any actual costs incurred during the period that have not yet been invoiced and the costs included in the contracts. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs. Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses. Stock-Based Compensation For stock-based awards granted to non-employees, employees and directors, the Company estimates the grant-date fair value of each award using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company accounts for forfeitures of stock-based awards as they occur rather than applying an estimated forfeiture rate to stock-based compensation expense. The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2020, the Company’s only element of other comprehensive income (loss) was a reclassification adjustment for gains included in net loss, net of tax. Net Income (Loss) per Share The Company follows the two-class method when computing net income (loss) per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of common shares outstanding for the period. Diluted net income (loss) is computed by adjusting net income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net income (loss) per share attributable to common stockholders is computed by dividing the diluted net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. The Company reported a net loss for each of the years ended December 31, 2021 and 2020 . Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50 % likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves (i.e., unrecognized tax benefits) that are considered appropriate as well as the related net interest. Recently Issued Accounting Pronouncements The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company will adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and will do so until such time tha

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The following tables present the Company’s fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis (in thousands): FAIR VALUE MEASUREMENTS AT LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Cash equivalents: Money market funds $ 142,547 $ - $ - $ 142,547 $ 142,547 $ - $ - $ 142,547 FAIR VALUE MEASUREMENTS AT LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Cash equivalents: Money market funds $ 170,097 $ — $ — $ 170,097 $ 170,097 $ — $ — $ 170,097 Money market funds were valued by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. There were no changes to the valuation methods during the years ended December 31, 2021 and 2020 . The Company evaluates transfers between levels at the end of each reporting period. There were no transfers between Level 1 or Level 2 during the years ended December 31, 2021 and 2020 .

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2021
Prepaid Expense And Other Assets Current [Abstract]
Prepaid Expenses and Other Current Assets	4. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): DECEMBER 31, 2021 2020 Prepaid expenses $ 4,027 $ 4,032 Other receivables 95 548 Interest receivable - 2 $ 4,122 $ 4,582

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property Plant And Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): DECEMBER 31, 2021 2020 Machinery and equipment $ 6,659 $ 6,139 Leasehold improvements 579 579 Furniture and fixtures 319 459 7,557 7,177 Less: Accumulated depreciation and amortization ( 4,511 ) ( 3,532 ) $ 3,046 $ 3,645 Depreciation and amortization expense was $ 1.2 million and $ 1.3 million for the years ended December 31, 2021 and 2020, respectively. In February 2020, as a result of the termination of the 2016 Lease (see Note 10), the Company removed from the consolidated balance sheet leasehold improvements with a cost of $ 2.7 million and accumulated depreciation related to those leasehold improvements of $ 1.3 million. The resulting $ 1.4 million loss was recognized as a component of the $ 0.1 million net loss recognized by the Company upon termination of the 2016 Lease (see Note 10).

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consisted of the following (in thousands): DECEMBER 31, 2021 2020 Accrued external research, development and manufacturing costs $ 2,156 $ 3,085 Accrued employee compensation and benefits 3,040 2,682 Accrued licensing fees (Note 11) — 743 Other 1,614 848 $ 6,810 $ 7,358

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	7. Stock-Based Compensation On October 20, 2020, the Company’s board of directors adopted, and on October 22, 2020 its stockholders approved, the 2020 Incentive Award Plan (the “2020 Plan”), which became effective the day prior to the first public trading date of the Company’s common stock. Following the effectiveness of the 2020 Plan, no further awards are made under the Company’s previous 2014 Stock Incentive Plan (the “2014 Plan”). The 2020 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares reserved for issuance under the 2020 Plan is subject to an annual increase on the first day of each calendar year, beginning on January 1, 2021 and ending on and including January 1, 2030, 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 and (ii) such smaller number of shares of common stock as is determined by the board of directors. The shares of common stock underlying any awards that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, repurchased or are otherwise terminated by the Company under the 2020 Plan or following the effective date of the 2020 Plan, under the 2014 Plan are added back to the shares of common stock available for issuance under the 2020 Plan. As of December 31, 2021, there were 2,685,500 shares available for future issuance under the 2020 Plan. On October 20, 2020, the Company’s board of directors adopted, and on October 22, 2020 its stockholders approved, the 2020 Employee Stock Purchase Plan (the ‘‘2020 ESPP’’), which became effective the day prior to the first public trading date of the Company’s common stock. The number of shares of common stock that may be issued under the 2020 ESPP automatically increases on the first day of each calendar year, beginning on January 1, 2021 and ending on and including January 1, 2030, equal to the lesser of (i) 1 % of the shares of common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of common stock as is determined by the board of directors, provided that not more than 3,724,461 shares of common stock may be issued under the 2020 ESPP. As of December 31, 2021 , 13,627 shares had been issued under the 2020 ESPP and 510,122 shares were available for issuance under the 2020 ESPP. Stock Option Valuation The fair value of each option is estimated on the date of grant using the Black-Scholes option-pricing model. Before November 3, 2020, the Company was a private company and until that time lacked company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer public companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of an option for time periods approximately equal to the expected term of the option. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employees is equal to the contractual term of the option award. The expected dividend yield of 0 % is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted: YEAR ENDED 2021 2020 Fair value of common stock $ 15.55 $ 7.70 Expected term (years) 6.0 6.0 Expected volatility 76.4 % 73.3 % Risk-free interest rate 0.90 % 0.60 % Expected annual dividend yield 0 % 0 % The following table summarizes the Company’s stock option activity since December 31, 2020: NUMBER OF WEIGHTED- WEIGHTED- INTRINSIC (in years) (in thousands) Outstanding at December 31, 2020 4,039,894 $ 7.69 8.41 $ 85,993 Granted 1,322,226 15.55 Exercised ( 333,417 ) 3.92 Forfeited or canceled ( 689,180 ) 11.66 Outstanding at December 31, 2021 4,339,523 $ 9.75 7.68 $ 8,823 Vested and expected to vest at December 31, 2021 4,339,523 $ 9.75 7.68 $ 8,823 Options exercisable at December 31, 2021 2,000,970 $ 6.33 6.46 $ 7,115 The weighted-average grant-date valuation of stock options granted during the years ended December 31, 2021 and 2020 was $ 10.26 per share and $ 7.70 per share, respectively. The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2021 and 2020 was $ 3.8 million and $ 4.4 million, respectively. Stock-Based Compensation Expense Stock-based compensation expense related to stock options and restricted stock awards was classified in the consolidated statements of operations as follows (in thousands): YEAR ENDED 2021 2020 Research and development expenses $ 3,243 $ 1,243 General and administrative expenses 5,262 2,359 $ 8,505 $ 3,602 In September 2021 and November 2021, the Company modified the terms of stock options previously granted to two executive officers. As a result of these modifications, the Company recorded an expense of approximately $ 1.4 million for the year ended December 31, 2021 to account for the incremental change in the fair value of the stock options before and after the modifications. Of this total expense, $ 0.9 million was recognized in research and development expenses. As of December 31, 2021 , total unrecognized stock-based compensation expense related to unvested stock-based awards was $ 16.1 million, which is expected to be recognized over a weighted-average period of 2.5 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes For the years ended December 31, 2021 and 2020 , the Company recorded no income tax benefits for the net operating losses incurred or for the research and development tax credits generated in each period, due to its uncertainty of realizing a benefit from those items. All of the Company’s operating losses since inception have been generated in the United States. A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: YEAR ENDED 2021 2020 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% State income taxes, net of federal benefit ( 6.0 ) ( 6.3 ) Federal and state research and development tax credits ( 3.8 ) ( 5.4 ) Change in deferred tax rate — 0.2 Other 0.6 ( 0.2 ) Change in deferred tax asset valuation allowance 30.2 32.7 Effective income tax rate 0.0 % 0.0 % The Company’s net deferred tax assets consisted of the following (in thousands): DECEMBER 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 42,897 $ 20,032 Research and development tax credit carryforwards 11,963 9,310 Deferred revenue 5,036 11,519 Accrued expenses 782 764 Operating lease liabilities 18,892 12,791 Stock-based compensation 2,118 816 Other 298 311 Total deferred tax assets 81,986 55,543 Valuation allowance ( 62,671 ) ( 41,894 ) Total deferred tax assets, net of valuation allowance 19,315 13,649 Deferred tax liabilities: Depreciation ( 382 ) ( 515 ) Operating lease right-of-use assets ( 18,933 ) ( 13,134 ) Total deferred tax liabilities ( 19,315 ) ( 13,649 ) Net deferred tax assets $ — $ — As of December 31, 2021, the Company had U.S. federal net operating loss (“NOL”) carryforwards of $ 158.4 million, which may be available to offset future taxable income, of which $ 11.3 million begin to expire in 2034 and of which $ 147.1 million do not expire but are generally limited in their usage to an annual deduction equal to 80 % of annual taxable income. In addition, as of December 31, 2021, the Company had state net operating loss carryforwards of $ 152.0 million, which may be available to offset future taxable income and begin to expire in 2035. As of December 31, 2021, the Company also had U.S. federal and state research and development tax credit carryforwards of $ 8.1 million and $ 4.9 million, respectively, which will begin to expire in 2034 and 2030 respectively. Utilization of the U.S. federal and state NOL carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, and corresponding provisions of state law, due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of NOL and research and development tax credit carryforwards that can be utilized annually to offset future taxable income or tax liabilities. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain stockholders or public groups in the stock of a corporation by more than 50 % over a three-year period. If a change in control has occurred at any time since the Company’s formation, utilization of its pre-change NOLs or research and development tax credit carryforwards would be subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, which could then be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the NOL carryforwards or research and development tax credit carryforwards before their utilization. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. Until a study is completed by the Company and any limitation is known, no amounts are being presented as an uncertain tax position. The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2021 and 2020. Management reevaluates the positive and negative evidence at each reporting period. The Company generated research credits for the tax years ending after December 31, 2013 but has not conducted a study to document qualified activities. This study may result in an adjustment to the Company's research and development carryforwards; however, until a study is completed, and any adjustment is known, no amounts are being presented as an unrecognized tax benefit for the year ended December 31, 2021. A full valuation allowance has been provided against the Company's research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research credit carryforward and the valuation allowance. For the years ended December 31, 2021 and 2020, the valuation allowance increased primarily due to increases in NOL carryforwards and research and development tax credit carryforwards as well as the increase in stock compensation awards partially offset by a decrease in deferred revenue and was as follows (in thousands): YEAR ENDED 2021 2020 Valuation allowance at beginning of year $ ( 41,894 ) $ ( 25,336 ) Increases recorded to income tax provision ( 20,777 ) ( 16,558 ) Valuation allowance at end of year $ ( 62,671 ) $ ( 41,894 ) As of December 31, 2021 and 2020 , the Company had no t recorded any amounts for unrecognized tax benefits. Interest and penalties related to income taxes are recorded as a component of the income tax provision in the consolidated statements of operations and comprehensive loss. As of December 31, 2021 and 2020 , the Company had no accrued interest or penalties related to uncertain tax positions and no amounts had been recognized in the consolidated statements of operations and comprehensive loss. The Company files income tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. The Company is open to future tax examination under statute from 2018 to the present; however, carryforward attributes that were generated prior to 2018 may still be adjusted upon examination by federal, state or local tax authorities if they either have been or will be used in a future period. The Company closed an examination by the Internal Revenue Service for the year ending December 31, 2018 with a minimal adjustment to its federal NOL carryforwards. The Company has not received any other notice of examination in any jurisdictions for any tax year open under statute.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Leases The Company’s commitments under its leases are described in Note 10. License and Supply Agreements License Agreement with Massachusetts Institute of Technology In December 2015, the Company entered into an exclusive patent license agreement with the Massachusetts Institute of Technology (“MIT”) (the “MIT Agreement”). The MIT Agreement replaced a May 2013 exclusive agreement with MIT. Under the MIT Agreement, the Company received an exclusive license under the licensed patent rights to develop, manufacture and commercialize any products related to certain intracellular delivery methods that were developed at MIT. Under the MIT Agreement, the Company also has the right to grant sublicenses of its rights during an exclusivity period that commences on the effective date of the MIT Agreement and expires on the date upon which all issued patents under the agreement have expired and all filed patent applications for the defined patent rights have been abandoned. Such sublicenses may extend past the expiration date of the exclusivity period; however, the exclusivity of such sublicenses expires at the end of the exclusivity period. During the exclusivity period, MIT may not grant any other license in the Company’s field of use under the licensed patent rights in the MIT Agreement, except that MIT may grant licenses under the agreement to specified parties. The Company is obligated to use diligent efforts to develop licensed products or licensed processes, to hire a specified number of employees to support the development effort to bring the licensed product or licensed process to commercialization, and to expend a minimum amount in the low single-digit millions annually that must be spent in support of this effort for the term of the MIT Agreement. There are also terms included in the MIT Agreement that require the Company to (i) reach certain thresholds of sublicense income within five years from the date of the amended effective date of the agreement or (ii) expend a minimum amount in the mid single-digit millions within five years on at least one fully funded project towards the development of a licensed product or licensed process. If the Company fails to meet these requirements, MIT may treat such failure as a material breach. Under the MIT Agreement, the Company is obligated to pay nonrefundable annual license maintenance fees of less than $ 0.1 million, which may be credited against royalties subsequently due on net sales of licensed products earned in the same calendar year, if any. In addition, the Company is obligated to make aggregate milestone payments to MIT of up to $ 1.8 million upon the achievement of specified milestones with respect to each licensed product, consisting of up to $ 0.8 million of development milestone payments and up to $ 1.0 million of regulatory milestone payments. The Company is also obligated to pay royalties of a low single-digit percentage to MIT based on (i) the Company’s, and any of its affiliates’ and sublicensees’, net sales of licensed products in the research field and (ii) the Company’s, and any of its affiliates’, net sales of licensed products in the therapeutic field. With respect to licensed products or licensed processes leased or sold by a sublicensee, the Company is required to pay MIT royalties equal to the lesser of a low single-digit percentage of each sublicensees’ net sales or a mid double-digit percentage of any royalty owed to the Company under a relevant sublicense agreement. The Company is also required to pay MIT a mid-teens percentage of any other sublicense income that the Company receives from sublicensees. The Company is also responsible for all costs related to the amendment, prosecution and maintenance of the licensed patent rights. The license granted by MIT to the Company is an exclusive license for the period from the effective date of the MIT Agreement through the date upon which all issued patents under the agreement have expired and all filed patent applications for the defined patent rights have been abandoned. MIT has the right to terminate the agreement if the Company fails to pay amounts when due or otherwise materially breaches the agreement and fails to cure such nonpayment or breach within specified cure periods or in the event the Company ceases to carry on its business related to the agreement. In the event of a termination due to the Company’s breach caused by a failure to meet its diligence requirements for a specified field, but where the Company has fulfilled its obligations with respect to a different specified field, MIT may not terminate the agreement with respect to the different specified field. MIT may immediately terminate the agreement if the Company or any of its affiliates brings specified patent challenges against MIT or assists others in bringing a patent challenge against MIT. The Company has the right to terminate the agreement for its convenience at any time on six months’ prior written notice to MIT and payment of all amounts due to MIT through the date of termination. As of December 31, 2020, the Company had a liability of $ 0.7 million included in accrued expenses (see Note 6) for amounts owed to MIT under the sublicense terms of the MIT Agreement. The Company had no liability to MIT under the sublicense terms of the MIT Agreement as of December 31, 2021. During both the years ended December 31, 2021 and 2020, the Company did no t recognize any research and development expense under the sublicense terms of the agreement. License Agreement with Erytech In June 2019, the Company entered into a license agreement with Erytech Pharma S.A. (“Erytech”), a French biopharmaceutical company developing therapies for severe forms of cancer and orphan diseases. Under the agreement, the Company received an exclusive worldwide license to develop red blood cell-based antigen-specific immune modulating therapies and has the right to grant sublicenses of its rights. Under the agreement, the Company paid an upfront fee of $ 1.0 million and is obligated to make aggregate milestone payments of up to $ 6.0 million upon the achievement of specified milestones, consisting of up to $ 1.0 million of development milestone payments and up to $ 5.0 million of regulatory milestone payments, for the first licensed product to achieve the specified milestones and payments of up to $ 50.0 million upon the achievement of specified sales milestones for all licensed products successfully developed under this agreement for each indication. In addition, the Company is obligated to pay tiered royalties ranging in the low single-digit percentages of annual net sales for each licensed product or licensed indication sold by the Company or its affiliates. Royalties will be paid by the Company on a licensed product-by-licensed product, indication-by-indication and country-by-country basis beginning on the first commercial sale of such licensed product for such indication in such country until expiration of the last valid patent claim covering such licensed product in such country. With respect to licensed products sublicensed to third parties, the Company is required to pay a low single-digits to low double-digits percentage of any sublicense income that it receives from sublicensees. The Company is also responsible for all costs related to the amendment, prosecution and maintenance of the licensed patent rights. The Company has the right to terminate the agreement, in whole or on a country-by-country basis, upon 60 days ’ notice to Erytech. In 2019, the Company paid the upfront fee of $ 1.0 million and recorded this amount as a research and development expense in its consolidated statement of operations and comprehensive loss. As of December 31, 2021 and 2020, the Company had not made any additional payments and had not accrued for any contingent payments as there were no development, regulatory or sales milestones that were probable of being achieved. Manufacturing Services Agreements During the years ended December 31, 2021 and 2020, the Company entered into agreements with a contract manufacturing organization to provide manufacturing services related to its product candidates as it began to prepare for future clinical trials. The Company had non-cancelable lease commitments representing one year of lease payments as of December 31, 2021 related to these agreements. These payments are included within the minimum lease payments for fiscal year 2022 in Note 10. 401(k) Plan The Company sponsors a 401(k) defined contribution benefit plan (the “401(k) Plan”), which covers all employees who meet certain eligibility requirements as defined in the 401(k) Plan and allows participants to defer a portion of their annual compensation on a pre-tax basis. Contributions to the 401(k) Plan may be made at the discretion of management. For the years ended December 31, 2021 and 2020, the Company contributed $ 0.4 million and $ 0.3 million, respectively to the 401(k) Plan. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to its vendors, lessors, contract research organizations, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. The Company has not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims. Legal Proceedings 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 as incurred the costs related to such legal proceedings.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	10. Leases As of December 31, 2021 and 2020, the Company leased its office and laboratory facilities under a non-cancelable operating lease entered into in December 2018, which includes lease incentives, payment escalations and rent holidays. The Company had not entered into any financing leases or any material short-term operating leases as of December 31, 2021 and 2020. 2016 Lease In September 2016, the Company entered into a lease for office and laboratory space in Watertown, Massachusetts (the “2016 Lease”). The 2016 Lease was set to expire in September 2023; however, in February 2020, the Company and the landlord jointly terminated the 2016 Lease. Accordingly, as of February 2020, the Company had no further obligations under the 2016 Lease. As a result of this termination, the Company removed from the consolidated balance sheet the associated operating lease right-of-use asset of $ 2.1 million, leasehold improvements with a net carrying value of $ 1.4 million (see Note 5) and operating lease liabilities of $ 3.4 million. The Company therefore recognized a net loss on termination of the 2016 Lease of $ 0.1 million in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020. 2018 Lease In December 2018, the Company entered into a lease for office and laboratory space in Watertown, Massachusetts (the “2018 Lease”). The 2018 Lease term commenced in December 2019 and expires in November 2029 . Under the 2018 Lease, the Company has one five-year option to extend the term of the lease. The initial annual base rent was $ 3.8 million upon entering into the lease, with such base rent increasing during the initial term by 3 % annually on the anniversary of the commencement date. The Company is obligated to pay its portion of real estate taxes and costs related to the premises, including costs of operations, maintenance, repair, replacement and management of the new leased premises. In connection with the lease, the Company maintains a letter of credit for the benefit of the landlord in the amount of $ 2.3 million, for which the Company is required to maintain a separate cash balance of the same amount. The 2018 Lease Agreement includes a landlord-provided tenant improvement allowance of $ 9.8 million that was applied to the costs of the construction of leasehold improvements. Embedded Lease The Company evaluated its vendor contracts to identify embedded leases, if any, and noted that an agreement entered into in April 2019 with a contract manufacturing supplier constituted a lease under ASC 842 because the Company has the right to substantially all of the economic benefits from the use of the asset and can direct the use of the asset. The embedded lease commenced in September 2019 and initially expired 24 months from the commencement date, with no stated option to extend the term. Upon the commencement date, the Company recorded right-of-use assets and operating lease liabilities in equal amounts of $ 14.7 million in connection with this embedded lease. At various times in 2020 and 2021, the Company amended the terms of its agreement with the contract manufacturing supplier to allow for an increase in manufacturing runs, and to extend the term of the arrangement. These amendments resulted in an increase in the estimated future payments to be made by the Company to the contract manufacturing supplier. The Company determined that these amendments constituted modifications of the existing agreement under ASC 842, rather than separate contracts. Upon the modification in June 2020, the Company recorded increases in right-of-use assets and operating lease liabilities in equal amounts of $ 0.9 million. In September 2020, the Company's amendment of the agreement with its contract manufacturing supplier to extend the term of the agreement, which had the effect of extending the term of the embedded lease by one year through August 31, 2022 . The amendment increased the Company’s contractual payment obligations by $ 9.9 million, representing the monthly fees payable over that one-year extension. The amendment also included an option of the Company to further extend the term of the manufacturing services agreement by one additional year. The Company evaluated the probability of its exercising the option to extend the term of the agreement and concluded that it was reasonably certain that it would occur. The Company therefore recorded increases in right-of-use assets and operating liabilities in equal amounts of $ 16.2 million following the amendment. In September 2021, the Company amended the terms of its agreement to allow for an increase in manufacturing runs, and to extend the term of the agreement through December 2026. Upon the modification in September 2021, the Company recorded increases in right-of-use assets and operating lease liabilities in equal amounts of $ 31.3 million. Lease agreements The Company’s lease agreements, including the embedded lease, have terms ranging from five years to ten years . As noted above, the 2018 Lease includes an option to extend the lease for up to five years . This option would only be included in the determination of the amount of the lease liability when it is reasonably certain that the option will be exercised. When determining if a renewal option is reasonably certain of being exercised, the Company considers several economic factors, including, but not limited to, the significance of leasehold improvements incurred on the property, whether the asset is difficult to replace, underlying contractual obligations or specifics unique to that particular lease that would make it reasonably certain that the Company would exercise such option. Renewal and termination options were not included in the lease term for the Company’s new and existing operating leases as these options were not reasonably certain of being exercised. Right-of-use assets under operating leases at December 31, 2021 and 2020 totaled $ 69.8 million and $ 48.4 million, respectively. The leases do not include any restrictions or covenants that had to be accounted for under the lease guidance. Future minimum lease payments for operating leases with initial or remaining terms in excess of one year at December 31, 2021 were as follows (in thousands): YEAR ENDING DECEMBER 31, 2022 $ 14,816 2023 14,900 2024 15,025 2025 15,154 2026 14,007 Thereafter 14,088 Total lease payments 87,990 Less: Imputed interest ( 18,298 ) Total operating lease liabilities $ 69,692 Lease Portfolio The components of lease cost and supplemental information for the Company’s lease portfolio were as follows (in thousands, except term and discount rate amounts): YEAR ENDED 2021 2020 Lease cost: Operating lease cost $ 13,725 $ 12,607 Variable lease cost 1,963 1,164 Short-term lease cost — 21 $ 15,688 $ 13,792 DECEMBER 31, 2021 2020 Weighted-average remaining lease term (in years) 6.2 6.7 Weighted-average discount rate% 7.6 % 7.2 % Supplemental cash flow information related to the Company’s operating leases was as follows (in thousands): YEAR ENDED 2021 2020 Cash paid for amounts included in the measurement of operating lease liabilities: Operating cash flows from operating leases $ 12,611 $ 11,903

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2021
Research And Development [Abstract]
License and Collaboration Agreements	11. License and Collaboration Agreements 2017 License and Collaboration Agreement with Roche In April 2017, the Company entered into a second license and collaboration agreement with Roche (the “2017 Roche Agreement”) to allow Roche to use the Company’s Cell Squeeze technology to enable gene editing of immune cells to discover new targets in cancer immunotherapy. The 2017 Roche Agreement includes several licenses granted by Roche to the Company and by the Company to Roche in order to conduct a specified research program in accordance with a specified research plan. The 2017 Roche Agreement has a term that ends upon the earlier to occur of (i) the completion of all work under the research plan or (ii) two years after the effective date of the agreement. The collaboration term is subject to Roche’s right to extend the collaboration term for up to two additional one-year periods. Roche has the right to terminate the agreement, in whole or on a workstream-by-workstream basis, upon a specified amount of notice to the Company. The Company or Roche may terminate the agreement if the other party fails to cure its material breach within a specified period after receiving notice of such breach. Under the agreement, the Company received an upfront payment of $ 5.0 million as a technology access fee and is entitled to (i) payments of up to $ 1.0 million, in two tranches of $ 0.5 million, as reimbursement for the Company’s research costs; (ii) milestone payments of up to $ 7.0 million upon the achievement of specified development milestones; and (iii) annual maintenance fees ranging from $ 0.5 million to $ 0.9 million for each year following the fifth anniversary of the effective date, subject to specified prepayment discounts. The Company assessed its accounting for the 2017 Roche Agreement under ASC 606 as the transactions underlying the agreement were deemed to be transactions with a customer. The Company identified the following promises under the 2017 Roche Agreement: (i) a non-exclusive license granted to Roche to perform research related to and use the Company’s Cell Squeeze technology for gene editing of immune cells; (ii) specified research and development services related to gene editing of immune cells through the research term; (iii) manufacturing activities to support the specified research plan; and (iv) participation on a JRC. The annual maintenance fees described above were determined by the Company to be optional renewal payments. The Company concluded that each of the promises under the agreement was not distinct from the other promises in the arrangement. The research license was determined to not be distinct from the research and manufacturing activities primarily as a result of Roche being unable to benefit on its own or with other resources reasonably available in the marketplace because the license to the Company’s intellectual property requires significant specialized capabilities in order to be further developed, the research services necessary to develop the product are highly specialized, and the Company’s proprietary Cell Squeeze technology is a key capability of that development. The research and manufacturing services were determined not to be distinct because the promise under the agreement is to complete research and development, inclusive of the manufacturing. In addition, the Company determined that the impact of participation on the JRC was insignificant and had an immaterial impact on the accounting model. As such, the Company concluded that the first three promises should be combined into a single performance obligation. Based on these assessments, the Company identified one distinct performance obligation at the outset of the 2017 Roche Agreement. The Company recognizes revenue associated with the performance obligation as the research, development and manufacturing services are provided using an input method, based on the cumulative costs incurred compared to the total estimated costs expected to be incurred to satisfy the performance obligation. The transfer of control to the customer occurs over the time period that the research and development services are to be provided by the Company, and this cost-to-cost method is, in management’s judgment, the best measure of progress towards satisfying the performance obligation. To date, the amounts received from Roche that had not yet been recognized as revenue have been deferred as a contract liability in the Company’s consolidated balance sheet and have been recognized over the remaining research and development period until the performance obligation is satisfied. As of December 31, 2020, the Company had recorded as a contract liability, deferred revenue related to the 2017 Roche Agreement of $ 1.2 million. In early 2022, the Company received notice that the 2017 Roche Agreement was terminated and all active work streams under the 2017 Roche Agreement were concluded, and as of December 31, 2021, the Company concluded that it expected to incur no additional costs to satisfy the remaining performance obligations under the 2017 Roche Agreement and the Company recognized revenue of $ 1.2 million under the 2017 Roche Agreement. There was no remaining deferred revenue under the 2017 Roche Agreement as of December 31, 2021. During the year ended December 31, 2020, there were no significant changes in the total estimated costs expected to be incurred to satisfy the performance obligation under the 2017 Roche Agreement and the Company recognized revenue of $ 0.5 million under the 2017 Roche Agreement. 2018 License and Collaboration Agreement with Roche In October 2018, the Company entered into a third license and collaboration agreement with Roche (the “2018 Roche Agreement”) to jointly develop certain products based on mononuclear antigen presenting cells (“APCs”), including human papilloma virus (“HPV”), using the SQZ APC platform for the treatment of oncology indications. The Company granted Roche a non-exclusive license to its intellectual property, and Roche granted the Company a non-exclusive license to its and its affiliates’ intellectual property for the purpose of performing research activities. In connection with this agreement, the parties terminated the 2015 Roche Agreement described above. The 2018 Roche Agreement has a term that extends until all royalty, profit-share and other payment obligations expire or have been satisfied. Roche has the right to terminate the 2018 Roche Agreement, in whole or on a product-by-product basis, upon a specified amount of notice to the Company. The Company or Roche may terminate the agreement if the other party fails to cure its material breach within a specified period after receiving notice of such breach. Under the 2018 Roche Agreement, Roche was granted option rights to obtain an exclusive license to develop APC products or products derived from the collaboration programs on a product-by-product basis. These option rights are exercisable upon the achievement of clinical Phase 1 proof of concept and expire, if unexercised, as of a date specified in the agreement. In addition, Roche was granted an option right to obtain an exclusive license to develop a Tumor Cell Lysate (“TCL”) product. This option right is exercisable upon the achievement of clinical proof of concept and expires, if unexercised, as of a date specified in the agreement. For each of the APC products and TCL product, once Roche exercises its option and pays a specified incremental amount ranging from $ 15.0 million to $ 50.0 million for APC products and of $ 100.0 million for the TCL product, Roche will receive worldwide, exclusive commercialization rights for the licensed products, subject to the Company’s alternating option to retain U.S. APC commercialization rights. The Company will retain worldwide commercialization rights to any APC products or the TCL product for which Roche elects not to exercise its applicable option. For the first APC product that Roche exercises its option, Roche will receive worldwide, exclusive commercialization rights for the licensed product. On a product-by-product basis for the APC products, after the first product option is exercised by Roche and for every other product for which Roche exercises its option, the Company will retain an option to obtain the exclusive commercialization rights in the United States. Upon exercise of the TCL option by Roche, (i) the Company will be entitled to receive the aforementioned milestone payment of $ 100.0 million and (ii) profits from the TCL product will be shared equally by the Company and Roche. Through December 31, 2021 and 2020 Roche had not exercised any of its options under the 2018 Roche Agreement. Under the 2018 Roche Agreement, the Company received an upfront payment of $ 45.0 million and is eligible to receive (i) reimbursement of a mid double-digit percentage of its development costs; (ii) aggregate milestone payments on a product-by-product basis of up to $ 1.6 billion upon the achievement of specified milestones, consisting of up to $ 217.0 million of development milestone payments, up to $ 240.0 million of regulatory milestone payments and up to $ 1.2 billion of sales milestone payments; and (iii) tiered royalties on annual net sales of APC and TCL products licensed under the agreement, as described below. The Company received the upfront payment of $ 45.0 million in October 2018 upon execution of the agreement. In addition, during the second quarter of 2019, the Company received a payment of $ 10.0 million following the achievement of the first development milestone under the 2018 Roche Agreement related to submission by the Company of preclinical data to the U.S. Food and Drug Administration (“FDA”), and during the first quarter of 2020, the Company received a payment of $ 20.0 million following the achievement of the second development milestone under the 2018 Roche Agreement related to first-patient dosing in a Phase 1 clinical trial. Roche will pay tiered royalties based on annual net sales of APC and TCL products. If Roche exercises its option to obtain a license to commercialize an APC product, Roche will pay the Company tiered royalties on annual net sales of that licensed product at rates ranging from a mid single-digit percentage to a mid-teens percentage, depending on net sales of the product. If the Company exercises its option to obtain a license to develop an APC product in the United States, it will pay Roche tiered royalties on annual net sales of that licensed product at rates ranging from a mid single-digit percentage to a mid-teens percentage, depending on net sales of the product in the United States. For APC products selected by Roche, rather than mutually, Roche will pay the Company royalties on annual net sales of that licensed product at rates ranging from a mid single-digit percentage to a high single-digit percentage, depending on net sales of the product. For APC products that are selected mutually and for which the Company has not exercised its option to commercialize the product in the United States, Roche will pay the Company tiered royalties on annual net sales of that licensed product at a rate ranging from a high single-digit percentage to a mid-teens percentage, depending on net sales of the product. For TCL products, Roche will pay the Company tiered royalties on the aggregate net sales of all TCL products at rates ranging from either a mid-single digit percentage to a percentage in the low twenties, with the caveat that the rates for sales in the United States may instead range from a low-teens percentage to a percentage in the mid twenties, depending on whether and when the Company opts out of sharing certain profits and costs of commercializing the TCL product in the United States with Roche. The Company assessed its accounting for the 2018 Roche Agreement in accordance with ASC 606 and concluded that Roche is a customer prior to the exercise of any of its options under the agreement. The Company also identified the following promises under the 2018 Roche Agreement: (i) a non-exclusive license granted to Roche to use the Company’s intellectual property and collaboration compounds to conduct research activities related to the research plans under the 2018 Roche Agreement; (ii) specified research and development services related to HPV through Phase 1 clinical trials under a specified research plan; (iii) manufacturing of the Company’s SQZ APC platform and equipment in order to support the HPV research plan; (iv) specified research and development services on next-generation APCs under a research plan; (v) specified research and development services on TCL under a research plan; and (vi) participation on a joint steering committee (“JSC”). The Company concluded that, in the case of each performance obligation, the license to its intellectual property was not distinct as a result of Roche being unable to benefit from the license on its own or with other resources reasonably available in the marketplace because the license to its intellectual property requires significant specialized capabilities in order to be further developed. The Company concluded that the license to its intellectual property, research and development activities related to HPV, and manufacturing of the Company’s SQZ APC platform and equipment related to HPV were not distinct from each other because the research and manufacturing activities together customize and significantly modify the underlying technology. As such, the Company determined that each of these related promises under the agreement was not distinct from the others in this group and should be combined into a single performance obligation. The Company also concluded that the license to its intellectual property and the research and development activities on next-generation APCs were not distinct from each other because the research and development activities customize and significantly modify the underlying technology. As such, the Company determined that these related promises should be combined into a single performance obligation. Further, the Company concluded that the license to its intellectual property and the research and development activities on TCL were not distinct from each other because the research and development activities customize and significantly modify the underlying technology. As such, the Company determined that these related promises should be combined into a single performance obligation. The Company concluded that the three performance obligations were distinct from each other as they are separate programs and are unrelated. In addition, the Company determined that the impact of participation on the JSC was insignificant and had an immaterial impact on the accounting model. Finally, the Company evaluated the option rights for licenses to develop, manufacture and commercialize the collaboration targets to determine whether these options provide Roche with any material rights for accounting purposes. The Company concluded that the option exercise prices were not below respective standalone selling prices, and, therefore, the options were marketing offers that do not provide material rights under ASC 606. Accordingly, the options were excluded as performance obligations at the outset of the 2018 Roche Agreement and will be accounted for as separate accounting contracts if and when each option exercise occurs. Based on these assessments, the Company identified three performance obligations at the outset of the 2018 Roche Agreement: (1) the license to the Company’s intellectual property, the research and development activities related to HPV through Phase 1 clinical trials under a specified research plan, and the manufacturing of the Company’s SQZ APC platform and equipment in order to support the HPV research plan (the “first performance obligation”); (2) the license to the Company’s intellectual property and the research and development activities on next-generation APCs (the “second performance obligation”); and (3) the license to the Company’s intellectual property and the research and development activities on TCL (the “third performance obligation”). As of entering into the 2018 Roche Agreement, the Company assessed whether the 2018 Roche Agreement was, for accounting purposes, a modification of the two prior Roche agreements or a separate contract and concluded that it was a modification of the 2015 Roche Agreement. At the termination of the 2015 Roche Agreement, all deliverables were submitted to Roche for review, and as such, the Company completed all of its obligations under the 2015 Roche Agreement. Because the obligations under the 2015 Roche Agreement were completed at its termination and all arrangement consideration had been recognized as revenue, the accounting treatment as a modification determined by the Company would result in the same measurement and recognition patterns as would a separate contract. Further, the Company concluded that the 2018 Roche Agreement was a separate contract from the 2017 Roche Agreement because (i) the Company contracted to provide distinct goods and services associated with its gene editing platform to discover new targets in cancer immunotherapy, (ii) the 2018 Roche Agreement and 2017 Roche Agreement were not negotiated together as a package with a single commercial objective and (iii) the amount of consideration paid under the 2018 Roche Agreement and 2017 Roche Agreement are not dependent on the price or performance under the other agreement. In addition, the Company determined that the upfront payment of $ 45.0 million as well as the reimbursable costs of $ 10.8 million estimated by the Company constituted the entirety of the consideration to be included in the transaction price. This transaction price of $ 55.8 million was initially allocated to the three performance obligations based on the relative standalone selling price of each obligation. The potential milestone payments that the Company may be eligible to receive were excluded from the transaction price at the outset of the arrangement because (i) all development and regulatory milestone payments did not meet the criteria for inclusion using the most-likely-amount method and (ii) the Company recognizes as revenue sales-based royalties and milestone payments at the later of the occurrence of the related sales or the date upon which the performance obligation has been satisfied because the Company believes that the license is the predominant item to which the royalties relate and has applied the sales-based royalty exception. The Company reevaluates the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, the Company will adjust its estimate of the transaction price. The Company determined the standalone selling price of each performance obligation under the 2018 Roche Agreement based on its estimate of its costs to be incurred to fulfil the research, development and manufacturing obligations associated with each of the three performance obligations, plus a reasonable margin. During the fourth quarter of 2019, the Company evaluated its overall program priorities and determined that in 2020 it would continue to focus its resources on progressing the specified APC programs related to the 2018 Roche Agreement as well as its Activating Antigen Carriers (“AAC”) and Tolerizing Antigen Carriers (“TAC”) platforms. As a result of its continuing focus on these specific programs, the Company reduced the level of priority of the TCL research activities under the 2018 Roche Agreement and expects to perform such TCL research activities over a longer time period than as originally expected under the specified research plan of the agreement. Since the fourth quarter of 2019, the Company has classified $ 9.2 million as non-current deferred revenue in its consolidated balance sheet which will remain unrecognized as revenue until TCL research activities resume or the 2018 Roche Agreement is modified by the Company and Roche. The Company separately recognizes revenue associated with each of the three performance obligations as the research, development and manufacturing services are provided using an input method, based on the cumulative costs incurred compared to the total estimated costs expected to be incurred to satisfy each performance obligation. The transfer of control to the customer occurs over the time period that the research and development services are to be provided by the Company, and this cost-to-cost method is, in management’s judgment, the best measure of progress towards satisfying each performance obligation. The amounts received that have not yet been recognized as revenue are deferred as a contract liability in the Company’s consolidated balance sheet and will be recognized over the remaining research and development period until each performance obligation is satisfied. During the year ended December 31, 2021 , the total estimated costs expected to be incurred to satisfy the performance obligations under the 2018 Roche Agreement decreased by $ 7.3 million. During the year ended December 31, 2020 , the total estimated costs expected to be incurred to satisfy the performance obligations increased by $ 7.3 million. In the fourth quarter of 2021, the Company became entitled to receive a milestone payment of $ 3.0 million upon (i) the recommendation by an independent panel that we could advance our SQZ-PBMC-HPV clinical trial to combination therapy to checkpoint initiators and (ii) the initiation of that therapy. The Company achieved both requirements in the fourth quarter of 2021 and therefore included the $ 3.0 million milestone payment in its estimate of the transaction price for the 2018 Roche Agreement. As a result, the Company recorded a cumulative catch-up adjustment to collaboration revenue of $ 2.5 million during the year ended December 31, 2021. The Company recognized revenue of $ 25.8 million and $ 20.5 million during the years ended December 31, 2021 and 2020, respectively, under the 2018 Roche Agreement. As of December 31, 2021 and 2020 , the Company recorded as a contract liability deferred revenue related to the 2018 Roche Agreement of $ 21.2 million and $ 44.0 million, respectively, of which $ 12.0 million and $ 24.7 million, respectively, were current liabilities. As of December 31, 2021 , the research and development services related to the first performance obligation was expected to be performed over remaining period of one year . As of December 31, 2020 , the research and development services related to the first and second performance obligations were expected to be performed over remaining periods ranging from one year to 1.5 years. As of December 31, 2021, the expected remaining period of performance of the Company’s research and development services related to the third performance obligation was not determinable, and it will not become determinable until TCL research activities resume, or the 2018 Roche Agreement is modified by the Company and Roche. Contract Liability The changes in the total contract liability (deferred revenue) balances related to the Company’s license and collaboration agreements with Roche were as follows (in thousands): YEAR ENDED 2021 2020 Balance at beginning of period $ 45,201 $ 40,453 Deferral of revenue 3,100 25,746 Recognition of deferred revenue ( 27,098 ) ( 20,998 ) Balance at end of period $ 21,203 $ 45,201 During the years ended December 31, 2021 and 2020 , the Company recognized revenue of $ 24.5 million and $ 16.3 million, respectively, related to deferred revenue that was recorded as a contract liability at the beginning of each respective year.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share	12. Net Loss per Share Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): YEAR ENDED 2021 2020 Numerator: Net loss $ ( 68,741 ) $ ( 50,521 ) Denominator: Weighted-average common shares outstanding, basic and diluted 27,578,844 5,401,895 Net loss per share attributable to common stockholders, basic and diluted $ ( 2.49 ) $ ( 9.35 ) The Company’s potential dilutive securities, which consist of common stock options have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: YEAR ENDED 2021 2020 Stock options to purchase common stock 4,339,523 4,039,894 4,339,523 4,039,894

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
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 reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, the accrual of research and development expenses, the valuation of common stock and the valuation of stock-based awards. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions.
Concentrations of Credit Risk and of Significant Suppliers	Concentrations of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of accounts receivable and cash and cash equivalents. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. As of December 31, 2021 and 2020, all of the Company’s accounts receivable were related to its collaboration agreements with Roche (see Note 11). The Company relies, and expects to continue to rely, on a small number of vendors to manufacture supplies and to process its product candidates for its development programs. These programs could be adversely affected by a significant interruption in the manufacturing process or supply chain.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid investments in marketable securities with original maturities of three months or fewer at the date of purchase to be cash equivalents.
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 financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering in stockholder’s equity as a reduction of additional paid-in capital generated as a result of the offering. Should the in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss. Deferred offering costs as of December 31, 2021 are expenses directly related to the Form S-3 filed with the SEC on November 12, 2021 and declared effective on November 18, 2021 (the "Shelf Registration"). These costs consist of legal, accounting, printing and filing fees that the Company has capitalized, including fees incurred by the independent registered public accounting firm directly related to the Shelf Registration. Deferred costs associated with the Shelf Registration are reclassified to additional paid in capital on a pro-rata basis when the Company completes offerings under the Shelf Registration, with any remaining deferred offering costs to be charged to the results of operations if the planned offering is abandoned, or at the end of the three-year life of the Shelf Registration. The Company had $ 0.3 million and $ 0 of deferred offering costs as of December 31, 2021 and 2020 , respectively.
Accounts Receivable Allowance	Accounts Receivable Allowance Accounts receivable are presented net of an allowance for doubtful accounts, which is an estimate of amounts that may not be collectible. The Company performs ongoing evaluations of its accounts receivable and, if necessary, provides an allowance for doubtful accounts and expected losses. The Company writes off accounts receivable against the allowance when it determines a balance is uncollectible and no longer actively pursues collection of the receivable. As of December 31, 2021 and 2020 , the Company had no allowance for doubtful accounts. During the years ended December 31, 2021 and 2020 the Company did no t record any provisions for doubtful accounts and did no t write off any accounts receivable balances.
Restricted Cash	Restricted Cash As of December 31, 2021 and 2020 , the Company maintained letters of credit totaling $ 2.3 million for the benefit of the landlord of its leased properties. The Company was required to maintain separate cash balances of $ 2.3 million to secure the letters of credit. The Company classified these separate cash balances of $ 2.3 million as restricted cash (non-current) in the consolidated balance sheets as of December 31, 2021 and 2020 based on the release dates of the restrictions on this cash. As of December 31, 2021 and 2020, the cash, cash equivalents and restricted cash of $ 145.8 million and $ 172.7 million, respectively, presented in the consolidated statements of cash flows included cash and cash equivalents of $ 143.5 million and $ 170.4 million, respectively, and restricted cash of $ 2.3 million for each of the years ended December 31, 2021 and 2020 .
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows: ESTIMATED USEFUL LIFE Machinery and equipment 3 to 5 years Furniture and fixtures 7 years Leasehold improvements Shorter of term of lease or 7 years Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated in accordance with the above guidelines once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are expensed as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. The Company continually evaluates long-lived assets for potential impairment whenever events or changes in circumstances indicate that the carrying value of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares the carrying values of the asset group to the expected future undiscounted cash flows that the asset group is expected to generate from the use and eventual disposition of the long-lived asset group. An impairment loss would be recognized in loss from operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. If such asset group is considered to be impaired, the impairment loss to be recognized would be based on the excess of the carrying value of the impaired asset group over its fair value. The Company did no t recognize any impairment losses on long-lived assets during the years ended December 31, 2021 and 2020 .
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. 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—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The fair value of the Company’s cash equivalents are determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts receivable, unbilled receivables, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities.
Leases	Leases The Company accounts for leases under Accounting Standards Codification (“ASC”) 842, Leases (“ASC 842”). The Company has operating leases for office space as well as a contract for manufacturing under which the Company has a dedicated suite. The Company may enter into similar arrangements in the future. Under ASC 842, the Company determines whether such arrangements contain a lease at the inception of a contract by assessing whether there is an identified asset and whether a contract conveys the right to control the use of the identified asset in exchange for consideration and the right to obtain the economic benefits from the use of the identified asset. Upon commencement of an identified lease, the Company records a right-of-use asset, which represents the Company’s right to use the underlying asset for the lease term, and records a lease liability, which represents the Company’s obligation to make lease payments arising from the lease. Right-of-use assets and lease liabilities are recognized at commencement date of the lease based on the present value of the future minimum lease payments over the lease term. Lease payments are discounted at the lease commencement date using the rate implicit in the lease, unless that rate is not readily determinable. As most of the Company’s leases do not provide an implicit rate, the Company determines an incremental borrowing rate, which represents an internally estimated rate that would be incurred by the Company to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment, based on the information available at the commencement date of each lease in determining the present value of the future minimum lease payments. The determination of the incremental borrowing rate is a significant management judgment, which is based on an analysis that includes the credit rating of the Company, geographical risk, and U.S. Treasury and corporate bond yields. After lease commencement and the establishment of a right-of-use asset and operating lease liability, lease expense is recorded on a straight-line basis over the lease term. As permitted by ASC 842, leases with an initial term of 12 months or fewer are not recorded in the consolidated balance sheets. The Company often enters into contracts that contain both lease and non-lease components. Non-lease components include real estate taxes, insurance, maintenance, utilities and other operating costs. The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single component. Variable costs, such as utilities or maintenance costs, are not included in the measurement of right-of-use assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs. The Company’s lease terms often include renewal options. The amounts determined for the Company’s right-of-use assets and lease liabilities generally do not assume that any renewal options or any early-termination provisions, if any, are exercised, unless it is reasonably certain that the Company will exercise such options.
Segment Information	Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company is developing methods of engineering cell function and therapies for the treatment of patients across a range of indications. The Company has determined that its chief operating decision maker is its Chief Executive Officer. The Company’s chief operating decision maker reviews the Company’s financial information on a consolidated basis for purposes of allocating resources and assessing financial performance. All of the Company’s tangible assets are held in the United States, and all of the Company’s collaboration revenue is derived from its collaboration partner headquartered in Switzerland.
Revenue Recognition for License and Collaboration Arrangements	Revenue Recognition for License and Collaboration Arrangements Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract, determines which goods or services are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when, or as, that performance obligation is satisfied. The Company enters into licensing arrangements that are within the scope of ASC 606, under which it may exclusively license to third parties rights to research, develop, manufacture and commercialize its product candidates. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront license fees; reimbursement of certain costs; customer option exercise fees; development, regulatory and sales milestone payments; and royalties on net sales of licensed products. The payment terms under the Company’s existing licensing arrangements are 60 days. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its arrangements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the assessment of the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when, or as, the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above; and (c) the standalone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above. The Company also uses judgment to determine whether milestone payments or other variable consideration, except for royalties and sales-based milestones, should be included in the transaction price, as described below. The transaction price is allocated to each performance obligation based on the relative standalone selling price of each performance obligation in the contract, and the Company recognizes revenue based on those amounts when, or as, the performance obligations under the contract are satisfied. The standalone selling price is the price at which an entity would sell a promised good or service separately to a customer. Management estimates the standalone selling price of each of the identified performance obligations in the Company’s customer contracts, maximizing the use of observable inputs. Because the Company has not sold the same goods or services in its contracts separately to any customers on a standalone basis and there are no similar observable transactions in the marketplace, the Company estimates the standalone selling price of each performance obligation in its customer arrangements based on its estimate of costs to be incurred to fulfil its obligations associated with the performance, plus a reasonable margin. The Company has determined that its only contract liability under ASC 606 is deferred revenue. Amounts received prior to revenue recognition are recorded as deferred revenue in the consolidated balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue in the consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion, in the consolidated balance sheets. Exclusive Licenses If the license to the Company’s intellectual property is determined to be distinct from the other promises or performance obligations identified in the arrangement, the Company recognizes revenue from nonrefundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. In assessing whether a promise or performance obligation is distinct from the other promises, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from a promise for its intended purpose without the receipt of the remaining promises, whether the value of the promise is dependent on the unsatisfied promises, whether there are other vendors that could provide the remaining promises, and whether it is separately identifiable from the remaining promises. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of progress and related revenue recognition. The measure of progress, and the resulting periods over which revenue should be recognized, are subject to estimates by management and may change over the course of the research, development and licensing arrangement. Such a change could have a material impact on the amount of revenue the Company records in future periods. Under the Company’s existing license and collaboration agreements, the Company has concluded that the transfer of control to the customer occurs over the time period that the research and development services are to be provided by the Company, and this cost-to-cost method is, in management’s judgment, the best measure of progress towards satisfying the performance obligation. Research and Development Services The promises under the Company’s license and collaboration arrangements often include research and development services to be performed by the Company on behalf of the partner. Payments or reimbursements resulting from the Company’s research and development efforts are estimated at the outset of the arrangement and considered part of the transaction price that is subsequently recognized as revenue because the Company is the principal in the arrangement for such efforts. Customer Options If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the Company evaluates the customer options to determine if they are material rights at the outset of each arrangement. Options to acquire additional goods or services for free or at a discount are deemed to be material rights. If the goods and services underlying the customer options are not determined to be material rights, these customer options are not considered to be performance obligations in the arrangement because they are contingent upon exercise of the option. If the customer options are determined to be a material right, the material right is recognized as a separate performance obligation at the outset of the arrangement. The Company allocates the transaction price to material rights based on the relative standalone selling price, which is determined based on the identified discount and the probability that the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised. Milestone Payments At the inception of each arrangement that includes potential research, development or regulatory milestone payments, the Company evaluates whether the milestones are considered likely to be met and estimates the amount to be considered for inclusion in the transaction price using the most-likely-amount method. If it is probable that a significant reversal in the amount of cumulative revenue recognized would not occur, the associated milestone payment value is included in the transaction price. For milestone payments due upon events that are not within the control of the Company or the licensee, such as regulatory approvals, the Company is not able to assert that it is likely that the regulatory approval will be granted and that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur until those approvals are received. In making this assessment, the Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the particular milestone. There is considerable judgment involved in determining whether it is probable that a significant reversal in the amount of cumulative revenue recognized would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price of the arrangement. Any such adjustments are recorded on a cumulative catch-up basis, which would affect the amounts of revenue and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments due upon first commercial sales or based on a level of sales, that are the result of a customer-vendor relationship and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) the occurrence of the related sales or (ii) the date upon which the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. To date, the Company has not recognized any royalty revenue from any of its licensing arrangements.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, laboratory supplies, depreciation, manufacturing expenses and external costs of vendors engaged to conduct preclinical development activities and clinical trials, as well as the costs of licensing technology and costs related to collaboration arrangements. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed, or when it is no longer expected that the goods will be delivered or the services rendered.
Research and Manufacturing Contract Costs and Accruals	Research and Manufacturing Contract Costs and Accruals The Company has entered into various research, development and manufacturing contracts with research institutions and other companies in the United States. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research, development and manufacturing costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research, development and manufacturing activities, invoicing to date under the contracts, communication from the research institutions and other companies of any actual costs incurred during the period that have not yet been invoiced and the costs included in the contracts. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.
Stock-Based Compensation	Stock-Based Compensation For stock-based awards granted to non-employees, employees and directors, the Company estimates the grant-date fair value of each award using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. The Company accounts for forfeitures of stock-based awards as they occur rather than applying an estimated forfeiture rate to stock-based compensation expense. The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2020, the Company’s only element of other comprehensive income (loss) was a reclassification adjustment for gains included in net loss, net of tax.
Net Income (Loss) per Share	Net Income (Loss) per Share The Company follows the two-class method when computing net income (loss) per share, as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of common shares outstanding for the period. Diluted net income (loss) is computed by adjusting net income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net income (loss) per share attributable to common stockholders is computed by dividing the diluted net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. The Company reported a net loss for each of the years ended December 31, 2021 and 2020 .
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50 % likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves (i.e., unrecognized tax benefits) that are considered appropriate as well as the related net interest.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company will adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for nonpublic companies. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses ( Topic 326 ): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes will result in the earlier recognition of credit losses, if any. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief (“ASU 2019-05”) , which provides additional implementation guidance on the previously issued ASU 2016-13. For public entities, this guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For the Company, this guidance is effective for fiscal years beginning after December 15, 2022. Early adoption is permitted as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2016-13 will have on its consolidated financial statements, however the Company does not expect that the standard will have a material impact on its consolidated financial statements. In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 (“ASU 2018-18”). ASU 2018-18 makes targeted improvements to GAAP for collaborative arrangements, including (i) clarification that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaborative arrangement participant is a customer in the context of a unit of account, (ii) adding unit-of-account guidance in ASC 808, Collaborative Arrangements , to align with the guidance in ASC 606 and (iii) a requirement that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under ASC 606 is precluded if the collaborative arrangement participant is not a customer. For the Company, this guidance was effective for fiscal years beginning after December 15, 2020. The Company adopted ASU 2018-18 as of January 1, 2021 and the standard did not have an impact on its consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (Topic 740) (“ASU 2019-12”), which simplifies the accounting for income taxes by eliminating certain exceptions, including the approach for intraperiod tax allocation, the accounting for income taxes in an interim period, hybrid taxes and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. For the Company, this guidance is effective for fiscal years beginning after December 15, 2021. Early adoption is permitted in interim or annual periods with any adjustments reflected as of the beginning of the fiscal year of adoption. Additionally, entities that elect early adoption must adopt all changes as a result of ASU 2019-12. The Company is currently evaluating the impact that the adoption of ASU 2019-12 will have on its consolidated financial statements, however the Company does not expect that the standard will have a material impact on its consolidated financial statements. In November 2021, the FASB issued ASU 2021-10, Disclosures by Business Entities about Government Assistance, which requires business entities to provide certain disclosures when they have 1) received government assistance and 2) use a grant or contribution accounting model by analogy to other accounting guidance. The guidance in ASU 2021-10 is effective for all entities for fiscal years beginning after December 15, 2021. Early adoption is permitted. The Company is currently evaluating the impact that the adoption of ASU 2021-10 would have on its financial statements, however the Company does not expect that the standard will have a material impact on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of property plant and equipment useful life	Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows: ESTIMATED USEFUL LIFE Machinery and equipment 3 to 5 years Furniture and fixtures 7 years Leasehold improvements Shorter of term of lease or 7 years

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Summary of fair value hierarchy for assets and liabilities	The following tables present the Company’s fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis (in thousands): FAIR VALUE MEASUREMENTS AT LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Cash equivalents: Money market funds $ 142,547 $ - $ - $ 142,547 $ 142,547 $ - $ - $ 142,547 FAIR VALUE MEASUREMENTS AT LEVEL 1 LEVEL 2 LEVEL 3 TOTAL Assets: Cash equivalents: Money market funds $ 170,097 $ — $ — $ 170,097 $ 170,097 $ — $ — $ 170,097

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Prepaid Expense And Other Assets Current [Abstract]
Summary of prepaid expenses and other current assets	Prepaid expenses and other current assets consisted of the following (in thousands): DECEMBER 31, 2021 2020 Prepaid expenses $ 4,027 $ 4,032 Other receivables 95 548 Interest receivable - 2 $ 4,122 $ 4,582

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property Plant And Equipment Net [Abstract]
Summary of property and equipment, net	Property and equipment, net consisted of the following (in thousands): DECEMBER 31, 2021 2020 Machinery and equipment $ 6,659 $ 6,139 Leasehold improvements 579 579 Furniture and fixtures 319 459 7,557 7,177 Less: Accumulated depreciation and amortization ( 4,511 ) ( 3,532 ) $ 3,046 $ 3,645

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Summary of accrued expenses	Accrued expenses consisted of the following (in thousands): DECEMBER 31, 2021 2020 Accrued external research, development and manufacturing costs $ 2,156 $ 3,085 Accrued employee compensation and benefits 3,040 2,682 Accrued licensing fees (Note 11) — 743 Other 1,614 848 $ 6,810 $ 7,358

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model	The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted: YEAR ENDED 2021 2020 Fair value of common stock $ 15.55 $ 7.70 Expected term (years) 6.0 6.0 Expected volatility 76.4 % 73.3 % Risk-free interest rate 0.90 % 0.60 % Expected annual dividend yield 0 % 0 %
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity since December 31, 2020: NUMBER OF WEIGHTED- WEIGHTED- INTRINSIC (in years) (in thousands) Outstanding at December 31, 2020 4,039,894 $ 7.69 8.41 $ 85,993 Granted 1,322,226 15.55 Exercised ( 333,417 ) 3.92 Forfeited or canceled ( 689,180 ) 11.66 Outstanding at December 31, 2021 4,339,523 $ 9.75 7.68 $ 8,823 Vested and expected to vest at December 31, 2021 4,339,523 $ 9.75 7.68 $ 8,823 Options exercisable at December 31, 2021 2,000,970 $ 6.33 6.46 $ 7,115
Summary of Stock-Based Compensation Expense	Stock-based compensation expense related to stock options and restricted stock awards was classified in the consolidated statements of operations as follows (in thousands): YEAR ENDED 2021 2020 Research and development expenses $ 3,243 $ 1,243 General and administrative expenses 5,262 2,359 $ 8,505 $ 3,602

Income Taxes (Table)

Income Taxes (Table)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
A reconciliation of the U.S. federal statutory income tax rate	A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: YEAR ENDED 2021 2020 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% State income taxes, net of federal benefit ( 6.0 ) ( 6.3 ) Federal and state research and development tax credits ( 3.8 ) ( 5.4 ) Change in deferred tax rate — 0.2 Other 0.6 ( 0.2 ) Change in deferred tax asset valuation allowance 30.2 32.7 Effective income tax rate 0.0 % 0.0 %
Net deferred tax assets	The Company’s net deferred tax assets consisted of the following (in thousands): DECEMBER 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 42,897 $ 20,032 Research and development tax credit carryforwards 11,963 9,310 Deferred revenue 5,036 11,519 Accrued expenses 782 764 Operating lease liabilities 18,892 12,791 Stock-based compensation 2,118 816 Other 298 311 Total deferred tax assets 81,986 55,543 Valuation allowance ( 62,671 ) ( 41,894 ) Total deferred tax assets, net of valuation allowance 19,315 13,649 Deferred tax liabilities: Depreciation ( 382 ) ( 515 ) Operating lease right-of-use assets ( 18,933 ) ( 13,134 ) Total deferred tax liabilities ( 19,315 ) ( 13,649 ) Net deferred tax assets $ — $ —
Summary of Valuation Allowance	For the years ended December 31, 2021 and 2020, the valuation allowance increased primarily due to increases in NOL carryforwards and research and development tax credit carryforwards as well as the increase in stock compensation awards partially offset by a decrease in deferred revenue and was as follows (in thousands): YEAR ENDED 2021 2020 Valuation allowance at beginning of year $ ( 41,894 ) $ ( 25,336 ) Increases recorded to income tax provision ( 20,777 ) ( 16,558 ) Valuation allowance at end of year $ ( 62,671 ) $ ( 41,894 )

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Schedule of Future Minimum lease Payments for Operating Leases	Future minimum lease payments for operating leases with initial or remaining terms in excess of one year at December 31, 2021 were as follows (in thousands): YEAR ENDING DECEMBER 31, 2022 $ 14,816 2023 14,900 2024 15,025 2025 15,154 2026 14,007 Thereafter 14,088 Total lease payments 87,990 Less: Imputed interest ( 18,298 ) Total operating lease liabilities $ 69,692
Summary of Operating Lease Lessee and Related Disclosures	The components of lease cost and supplemental information for the Company’s lease portfolio were as follows (in thousands, except term and discount rate amounts): YEAR ENDED 2021 2020 Lease cost: Operating lease cost $ 13,725 $ 12,607 Variable lease cost 1,963 1,164 Short-term lease cost — 21 $ 15,688 $ 13,792 DECEMBER 31, 2021 2020 Weighted-average remaining lease term (in years) 6.2 6.7 Weighted-average discount rate% 7.6 % 7.2 %
Summary of Supplementary Cash Flow Information Relating to Operating Leases	Supplemental cash flow information related to the Company’s operating leases was as follows (in thousands): YEAR ENDED 2021 2020 Cash paid for amounts included in the measurement of operating lease liabilities: Operating cash flows from operating leases $ 12,611 $ 11,903

License and Collaboration Agr_2

License and Collaboration Agreements (Tables)	12 Months Ended
	Dec. 31, 2021
Research And Development [Abstract]
Summary of Changes in the Total Contract Liability	The changes in the total contract liability (deferred revenue) balances related to the Company’s license and collaboration agreements with Roche were as follows (in thousands): YEAR ENDED 2021 2020 Balance at beginning of period $ 45,201 $ 40,453 Deferral of revenue 3,100 25,746 Recognition of deferred revenue ( 27,098 ) ( 20,998 ) Balance at end of period $ 21,203 $ 45,201

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Summary of basic and diluted net loss per share attributable to common stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): YEAR ENDED 2021 2020 Numerator: Net loss $ ( 68,741 ) $ ( 50,521 ) Denominator: Weighted-average common shares outstanding, basic and diluted 27,578,844 5,401,895 Net loss per share attributable to common stockholders, basic and diluted $ ( 2.49 ) $ ( 9.35 )
Summary of potentially dilutive shares excluded from the calculation of diluted net loss	The Company’s potential dilutive securities, which consist of common stock options have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: YEAR ENDED 2021 2020 Stock options to purchase common stock 4,339,523 4,039,894 4,339,523 4,039,894

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	Feb. 17, 2021USD ($)shares	Nov. 12, 2020USD ($)shares	Nov. 03, 2020USD ($)shares	Oct. 23, 2020	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Stock split ratio				1.0530
Income (loss) from continuing operations					$ 68,700
Accumulated deficit					$ 195,510	$ 126,769
Proceeds from issuance of convertible preferred stock, net of issuance costs paid in the period						$ 42,248
Initial Public Offering [Member]
Issuance of common stock (Shares) | shares			4,411,765
Proceeds from initial public offer net of underwriting discounts and before payment of offering costs		$ 75,500
Offering costs payable			$ 2,600
Common stock shares issued upon conversion | shares		17,800,084
Over-Allotment Option [Member]
Issuance of common stock (Shares) | shares		661,764
Follow-on Offering [Member]
Issuance of common stock (Shares) | shares	3,000,000
Proceeds from follow on public offer net of underwriting discounts and before payment of offering costs	$ 56,400
Offering costs payable	$ 800

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies [Line Items]
Deferred offering costs	$ 300,000	$ 0
Accounts Receivable, Allowance for Credit Loss	0	0
Provision For Doubtful Accounts	0	0
Accounts Receivable, Allowance for Credit Loss, Writeoff	0	0
Letter of credit outstanding	2,300,000	2,300,000
Restricted cash, noncurrent	2,300,000	2,300,000
Cash and cash equivalents, at carrying value	143,513,000	170,357,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	145,818,000	172,662,000	$ 41,574,000
Restricted Cash	2,300,000	2,300,000
Cash Balance To Be Maintained	2,300,000
Impairment losses on long-lived assets	$ 0	0
Income Tax Examination, Likelihood Percentage	50.00%
Operating lease right-of-use assets	$ 69,843,000	$ 48,360,000
Operating lease, liability	$ 69,692,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Property Plant and Equipment Useful Life (Detail)	12 Months Ended
	Dec. 31, 2021
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	Shorter of term of lease or 7 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value Hierarchy for Assets and Liabilities (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Assets, fair value disclosure	$ 142,547	$ 170,097
Level 1 [Member]
Assets:
Assets, fair value disclosure	142,547	170,097
Money Market Funds [Member] | Cash equivalents [Member]
Assets:
Assets, fair value disclosure	142,547	170,097
Money Market Funds [Member] | Cash equivalents [Member] | Level 1 [Member]
Assets:
Assets, fair value disclosure	$ 142,547	$ 170,097

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0
Fair value, liabilities, level 1 to level 2 transfers, amount	0	0
Fair value, liabilities, level 2 to level 1 transfers, amount	$ 0	$ 0

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid expenses	$ 4,027	$ 4,032
Other receivables	95	548
Interest receivable		2
Total prepaid expenses and other current assets	$ 4,122	$ 4,582

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment Net [Abstract]
Machinery and equipment	$ 6,659	$ 6,139
Leasehold improvements	579	579
Furniture and fixtures	319	459
Total property and equipment, gross	7,557	7,177
Less: Accumulated depreciation and amortization	(4,511)	(3,532)
Total property and equipment, net	$ 3,046	$ 3,645

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 29, 2020	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense		$ 1,208	$ 1,342
Leasehold improvements		579	579
Accumulated depreciation related to those leasehold improvements		4,511	3,532
Property and equipment, net		$ 3,046	3,645
Gain loss on termination of lease			$ (108)
2016 Lease [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements	$ 2,700
Accumulated depreciation related to those leasehold improvements	1,300
Gain loss on termination of lease	100
2016 Lease [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 1,400

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued external research, development and manufacturing costs	$ 2,156	$ 3,085
Accrued employee compensation and benefits	3,040	2,682
Accrued licensing fees (Note 11)		743
Other	1,614	848
Total accrued expenses	$ 6,810	$ 7,358

Preferred Stock - Additional In

Preferred Stock - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Proceeds from issuance of convertible preferred stock, net of issuance costs paid in the period		$ 42,248
Payment of issuance costs	$ 798
Series D Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Payment of issuance costs		$ 56

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 20, 2020	Dec. 31, 2021	Dec. 31, 2020
Stockbased Compensation [Line Items]
Expected annual dividend yield		0.00%	0.00%
Weighted-average grant-date fair value of stock options granted		$ 10.26	$ 7.70
Share based payments aggregate intrinsic value of stock options exercised		$ 3,800	$ 4,400
Stock based compensation expense due to modification of options		8,505	3,602
Unrecognized compensation expense related to unvested stock based awards		$ 16,100
Unrecognized compensation expense expected period for recognition		2 years 6 months
2020 Incentive Award Plan [Member]
Stockbased Compensation [Line Items]
Common stock shares reserved for future issuance		2,685,500
2020 Incentive Award Plan [Member] | Maximum [Member]
Stockbased Compensation [Line Items]
Percentage of aggregate number of shares of common stock outstanding	5.00%
2020 Employee Stock Purchase Plan [Member]
Stockbased Compensation [Line Items]
Common stock shares reserved for future issuance		510,122
Shares issued		13,627
2020 Employee Stock Purchase Plan [Member] | Maximum [Member]
Stockbased Compensation [Line Items]
Common stock shares reserved for future issuance	3,724,461
Percentage of aggregate number of shares of common stock outstanding	1.00%
Research and Development Expense [Member]
Stockbased Compensation [Line Items]
Stock based compensation expense due to modification of options		$ 3,243	$ 1,243
Stock Options [Member]
Stockbased Compensation [Line Items]
Stock based compensation expense due to modification of options		1,400
Stock Options [Member] | Research and Development Expense [Member]
Stockbased Compensation [Line Items]
Stock based compensation expense due to modification of options		$ 900

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Fair value of common stock	$ 15.55	$ 7.70
Expected term (years)	6 years	6 years
Expected volatility	76.40%	73.30%
Risk-free interest rate	0.90%	0.60%
Expected annual dividend yield	0.00%	0.00%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number Of Shares - Outstanding at December 31, 2020	4,039,894
Granted	1,322,226
Exercised	(333,417)
Forfeited or canceled	(689,180)
Number Of Shares - Outstanding at December 31, 2021	4,339,523	4,039,894
Number Of Shares - Vested and expected to vest at December 31, 2021	4,339,523
Number Of Shares - Options exercisable at December 31, 2021	2,000,970
Weighted Average Exercise price - Outstanding at December 31, 2020	$ 7.69
Granted	15.55
Exercised	3.92
Forfeited or canceled	11.66
Weighted Average Exercise price - Outstanding at December 31, 2021	9.75	$ 7.69
Weighted Average Exercise price - Vested and expected to vest at December 31, 2021	9.75
Weighted Average Exercise price - Options exercisable at December 31, 2021	$ 6.33
Weighted-Average Remaining Contractual Term	7 years 8 months 4 days	8 years 4 months 28 days
Weighted-Average Remaining Contractual Term - Vested and expected to vest	7 years 8 months 4 days
Weighted-Average Remaining Contractual Term - Options exercisable	6 years 5 months 15 days
Aggregate Intrinsic Value - Outstanding	$ 8,823	$ 85,993
Aggregate Intrinsic Value - Vested and expected to vest	8,823
Aggregate Intrinsic Value - Options exercisable	$ 7,115

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 8,505	$ 3,602
Research and Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	3,243	1,243
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 5,262	$ 2,359

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Income tax benefits	$ 0	$ 0
Miniumum ownership percentage to be maintanied by the existing owners	50.00%
Period for which minimum shareholding percentage shall be maintained	3 years
Accrued interest and penalties on unrecognised tax position	$ 0	0
Unrecognised tax penalties income tax penalties and interest expense	0	0
Unrecognized Tax Benefits	0	$ 0
Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	$ 158,400,000
Domestic Tax Authority [Member] | Maximum [Member]
Income Tax Disclosure [Line Items]
Percentage of net operating loss carryforwards eligible for deduction	80.00%
Domestic Tax Authority [Member] | Tax Year 2034
Income Tax Disclosure [Line Items]
Operating loss carryforwards	$ 11,300,000
Domestic Tax Authority [Member] | Can Be Indefinitely Carried Forward [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforwards	147,100,000
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Research and development tax credit forwards	152,000,000
State and Local Jurisdiction [Member] | Research [Member] | Tax Year 2035
Income Tax Disclosure [Line Items]
Research and development tax credit forwards	8,100,000
State and Local Jurisdiction [Member] | Research [Member] | Tax Year 2034 and 2030
Income Tax Disclosure [Line Items]
Research and development tax credit forwards	$ 4,900,000

Income Taxes - A reconciliation

Income Taxes - A reconciliation of the U.S. federal statutory income tax rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)
State income taxes, net of federal benefit	(6.00%)	(6.30%)
Federal and state research and development tax credits	(3.80%)	(5.40%)
Change in deferred tax rate		0.20%
Other	0.60%	(0.20%)
Change in deferred tax asset valuation allowance	30.20%	32.70%
Effective income tax rate	0.00%	0.00%

Income Taxes - Net deferred tax

Income Taxes - Net deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 42,897	$ 20,032
Research and development tax credit carryforwards	11,963	9,310
Deferred revenue	5,036	11,519
Accrued expenses	782	764
Operating lease liabilities	18,892	12,791
Stock-based compensation	2,118	816
Other	298	311
Total deferred tax assets	81,986	55,543
Valuation allowance	(62,671)	(41,894)	$ (25,336)
Total deferred tax assets, net of valuation allowance	19,315	13,649
Deferred tax liabilities:
Depreciation	(382)	(515)
Operating lease right-of-use assets	(18,933)	(13,134)
Total deferred tax liabilities	$ (19,315)	$ (13,649)

Income Taxes - Summary of Valua

Income Taxes - Summary of Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets Net Of Valuation Allowance [Abstract]
Valuation allowance at beginning of year	$ (41,894)	$ (25,336)
Increases recorded to income tax provision	(20,777)	(16,558)
Valuation allowance at end of year	$ (62,671)	$ (41,894)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Commitments and contingencies liabilities
Research and development	70,148,000	51,545,000
Discretionary contribution by the employer to defined contribution benefit plan	400,000	300,000
Sublicense Agreement [Member]
Other Commitments [Line Items]
Research and development	0	0
Massachusetts Institute of Technology [Member]
Other Commitments [Line Items]
Annual license maintenance fees	100,000
Milestone payment payable	1,800,000
Commitments and contingencies liabilities	0
Massachusetts Institute of Technology [Member] | Accrued expenses
Other Commitments [Line Items]
Commitments and contingencies liabilities		700,000
Massachusetts Institute of Technology [Member] | Regulatory Milestone [Member]
Other Commitments [Line Items]
Milestone payment payable	1,000,000
Massachusetts Institute of Technology [Member] | Development Milestone [Member]
Other Commitments [Line Items]
Milestone payment payable	$ 800,000
Manufacturing Services Agreements [Member]
Other Commitments [Line Items]
Non-cancelable lease commitments period for lease payments	1 year
Erytech [Member] | License Agreement With Erytech [Member]
Other Commitments [Line Items]
Milestone payment payable		6,000,000
Research and development		1,000,000	$ 1,000,000
Specified milestone payment payable		$ 50,000,000
Number of days notice for agreement termination		60 days
Erytech [Member] | License Agreement With Erytech [Member] | Regulatory Milestone [Member]
Other Commitments [Line Items]
Milestone payment payable		$ 5,000,000
Erytech [Member] | License Agreement With Erytech [Member] | Development Milestone [Member]
Other Commitments [Line Items]
Milestone payment payable		$ 1,000,000

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended						12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Feb. 29, 2020	Sep. 01, 2019	Dec. 31, 2018	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Letter of credit outstanding							$ 2,300	$ 2,300
Cost of construction of leasehold improvements							579	579
Operating lease right-of-use assets							69,843	48,360
Operating lease liability							31,307	17,049
Gain (loss) on termination of operating lease								(108)
Office Building [Member] | Watertown Massauchets [Member] | Two Thousand And Eighteen Lease Agreement [Member]
Lessee, Lease, Description [Line Items]
Lessee operating lease month of expiry						2029-11
Lessee operating lease renewal term						5 years
Initial annual base rent						$ 3,800
Initial annual base rent escalation percentage						3.00%
Letter of credit outstanding						$ 2,300
Cost of construction of leasehold improvements						$ 9,800
Office Building [Member] | Watertown Massauchets [Member] | Two Thousand And Eighteen Lease Agreement [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Operating lease term						5 years
Office Building [Member] | Watertown Massauchets [Member] | Two Thousand And Eighteen Lease Agreement [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Operating lease term						10 years
Office Building [Member] | Watertown Massauchets [Member] | Two Thousand And Sixteen Lease Agreement
Lessee, Lease, Description [Line Items]
Increase (decrease) in operating lease right of use assets				$ 2,100
Increase (decrease) in leasehold improvements operating lease				1,400
Increase (decrease) in operating lease liability				$ 3,400
Gain (loss) on termination of operating lease								100
Machinery and Equipment [Member] | Embedded Lease [Member]
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets					$ 14,700		$ 69,800	$ 48,400
Operating lease liability					$ 14,700
Operating lease term					24 months
Machinery and Equipment [Member] | Embedded Lease [Member] | Embedded Lease Amendment Agreement One [Member]
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 900
Operating lease liability			$ 900
Machinery and Equipment [Member] | Embedded Lease [Member] | Embedded Lease Amendment Agreement Two [Member]
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 31,300	$ 16,200
Operating lease liability	$ 31,300	16,200
Contractual payment obligations		$ 9,900
Operating lease date of expiry		Aug. 31, 2022

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum lease Payments for Operating Leases (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Leases [Abstract]
2022	$ 14,816
2023	14,900
2024	15,025
2025	15,154
2026	14,007
Thereafter	14,088
Total lease payments	87,990
Less: Imputed interest	(18,298)
Total operating lease liabilities	$ 69,692

Leases - Summary of Operating L

Leases - Summary of Operating Lease Lessee Balance Sheet and Related Disclosures (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lease cost:
Operating lease cost	$ 13,725	$ 12,607
Variable lease cost	1,963	1,164
Short-term lease cost		21
Lease Cost	$ 15,688	$ 13,792
Weighted-average remaining lease term (in years)	6 years 2 months 12 days	6 years 8 months 12 days
Weighted-average discount rate%	7.60%	7.20%

Leases - Summary of Supplementa

Leases - Summary of Supplementary Cash Flow Information Relating to Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating cash flows from operating leases	$ 12,611	$ 11,903

License and Collaboration Agr_3

License and Collaboration Agreements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended			12 Months Ended
	Oct. 31, 2018	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2018
License And Collaboration Agreements [Line Items]
Contract with customer liability revenue recognised					$ 27,098,000	$ 20,998,000
Contract with customer liability			$ 40,453,000		$ 21,203,000	45,201,000
2017 License and Collaboration Agreement With Roche [Member] | Roche [Member]
License And Collaboration Agreements [Line Items]
Term of license and collaboration agreement					2 years
Renewal term of license and collaboration agreement					1 year
Upfront payment received towards technology access fee					$ 5,000,000
Maximum reimbursement receivable for research and development costs incurred					1,000,000
Milestone payment receivable						7,000,000
Contract with customer liability revenue recognised					1,200	500,000
Contract with customer liability					0	1,200,000
Estimated costs to be incurred to satisfy performance obligation						0
2017 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Maximum [Member]
License And Collaboration Agreements [Line Items]
Annual maintenance fee receivable later than Five years						500,000
2017 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Minimum [Member]
License And Collaboration Agreements [Line Items]
Annual maintenance fee receivable later than Five years						900,000
2017 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Tranche One [Member]
License And Collaboration Agreements [Line Items]
Reimbursement receivable for research and development costs incurred						500,000
2017 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Tranche Two [Member]
License And Collaboration Agreements [Line Items]
Reimbursement receivable for research and development costs incurred						500,000
2018 License and Collaboration Agreement With Roche [Member]
License And Collaboration Agreements [Line Items]
Milestone payment receivable on exercise of option rights					100,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member]
License And Collaboration Agreements [Line Items]
Upfront payment received towards technology access fee	$ 45,000,000
Contract with customer liability					21,200,000	44,000,000
Contract with customer liability current					12,000,000	24,700,000
Milestone payment receivable based on product					1,600,000,000
Performance obligation transaction price							$ 55,800,000
Estimated costs to be incurred to satisfy performance obligation					(7,300,000)	7,300,000
Performance obligation revenue recognized					25,800,000	20,500,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Upfront Payment [Member]
License And Collaboration Agreements [Line Items]
Performance obligation transaction price							45,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Reimbursable Costs [Member]
License And Collaboration Agreements [Line Items]
Performance obligation transaction price							$ 10,800,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Development Milestone [Member]
License And Collaboration Agreements [Line Items]
Cumulative catch up adjustment to revenue					2,500,000
Milestone payment receivable based on product					217,000,000
Performance obligation transaction price					3,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Development Milestone [Member] | First Patient Doosing Phase One Clinical Trial [Member]
License And Collaboration Agreements [Line Items]
Milestone payment received		$ 20,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Regulatory Milestone [Member]
License And Collaboration Agreements [Line Items]
Milestone payment receivable based on product					240,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Regulatory Milestone [Member] | Preclinical Data Submitted To FDA For Approval [Member]
License And Collaboration Agreements [Line Items]
Milestone payment received				$ 10,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Sales Milestone [Member]
License And Collaboration Agreements [Line Items]
Milestone payment receivable based on product					1,200,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | APC [Member]
License And Collaboration Agreements [Line Items]
Amount payable on exercise of option rights to use the license					15,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | TCL [Member]
License And Collaboration Agreements [Line Items]
Contract liabilities current reclassified to non current			$ 9,200,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Maximum [Member] | TCL [Member]
License And Collaboration Agreements [Line Items]
Amount payable on exercise of option rights to use the license					100,000,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Minimum [Member]
License And Collaboration Agreements [Line Items]
Contract with customer liability revenue recognised					24,500,000	$ 16,300,000
2018 License and Collaboration Agreement With Roche [Member] | Roche [Member] | Minimum [Member] | TCL [Member]
License And Collaboration Agreements [Line Items]
Amount payable on exercise of option rights to use the license					$ 50,000,000

License and Collaboration Agr_4

License and Collaboration Agreements - Additional Information (Detail1) - Roche [Member] - 2018 License and Collaboration Agreement With Roche [Member]	Dec. 31, 2021	Dec. 31, 2020
Performance Obligation First [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
License And Collaboration Agreements [Line Items]
Remaining period over which the performance obligation is to be satisfied	1 year
Performance Obligation First And Second [Member] | Minimum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
License And Collaboration Agreements [Line Items]
Remaining period over which the performance obligation is to be satisfied		1 year
Performance Obligation First And Second [Member] | Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
License And Collaboration Agreements [Line Items]
Remaining period over which the performance obligation is to be satisfied		1 year 6 months

License and Collaboration Agr_5

License and Collaboration Agreements - Summary of Changes in the Total Contract Liability (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Research And Development [Abstract]
Balance at beginning of period	$ 45,201	$ 40,453
Deferral of revenue	3,100	25,746
Recognition of deferred revenue	(27,098)	(20,998)
Balance at end of period	$ 21,203	$ 45,201

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of basic and diluted net loss per share attributable to common stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Net loss	$ (68,741)	$ (50,521)
Weighted-average common shares outstanding, basic and diluted	27,578,844	5,401,895
Net loss per share attributable to common stockholders, basic and diluted	$ (2.49)	$ (9.35)

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of potentially dilutive shares excluded from the calculation of diluted net loss (Detail) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	4,339,523	4,039,894
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	4,339,523	4,039,894

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - IPO [Member] - USD ($) $ in Millions	Nov. 12, 2020	Nov. 03, 2020
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues		4,411,765
Proceeds from initial public offer net of underwriting discounts and before payment of offering costs	$ 75.5
Offering costs payable		$ 2.6