Surface Oncology (SURF) 10-K 2 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 28, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-38459
Entity Registrant Name	SURFACE ONCOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5543980
Entity Address, Address Line One	50 Hampshire Street
Entity Address, Address Line Two	8th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	714-4096
Title of 12(b) Security	Common stock, $0.0001
Trading Symbol	SURF
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 308,676,299
Entity Common Stock, Shares Outstanding		46,958,984
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement relating to the Annual Meeting of Shareholders, scheduled to be held on June 8, 2022, are incorporated by reference into Part III of this Report.
Entity Central Index Key	0001718108
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2021
Audit Information [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 56,045	$ 175,141
Marketable securities	98,104	0
Prepaid expenses and other current assets	3,197	5,368
Total current assets	157,346	180,509
Property and equipment, net	5,651	6,664
Operating lease right-of-use asset	25,870	27,911
Restricted cash	1,595	1,595
Other assets	385	459
Total assets	190,847	217,138
Current liabilities:
Accounts payable	1,550	1,674
Accrued expenses and other current liabilities	13,089	10,448
Operating lease liability	5,384	5,529
Total current liabilities	20,023	17,651
Operating lease liability, non-current	26,909	28,981
Convertible note payable, non-current	25,015	14,759
Total liabilities	71,947	61,391
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value per share; 5,000,000 shares authorized    at December 31, 2021 and December 31, 2020; no shares    issued and outstanding at December 31, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; 150,000,000 authorized at December 31, 2021    and December 31, 2020; 46,958,776 and 40,707,047 shares issued and    outstanding at December 31, 2021 and December 31, 2020, respectively	5	4
Additional paid-in capital	259,859	218,001
Accumulated other comprehensive loss	(221)	0
Accumulated deficit	(140,743)	(62,258)
Total stockholders’ equity	118,900	155,747
Total liabilities and stockholders’ equity	$ 190,847	$ 217,138

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (shares)	5,000,000	5,000,000
Preferred stock, issued (shares)	0	0
Preferred stock, outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (shares)	150,000,000	150,000,000
Common stock, issued (shares)	46,958,776	40,707,047
Common stock, outstanding (shares)	46,958,776	40,707,047

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Collaboration revenue - related party	$ 0	$ 38,592	$ 15,360
License-related revenue	2,687	87,570	0
Total revenue	2,687	126,162	15,360
Operating expenses:
Research and development	53,572	41,018	52,118
General and administrative	25,128	23,558	20,608
Total operating expenses	78,700	64,576	72,726
Income (loss) from operations	(76,013)	61,586	(57,366)
Interest expense	(2,546)	(2,855)	(145)
Other income (expense), net	74	606	2,722
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Net income (loss) per share - basic (in dollars per share)	$ (1.77)	$ 1.67	$ (1.97)
Weighted average commons shares outstanding—basic (shares)	44,243,317	35,545,121	27,854,912
Net income (loss) per share - diluted (in dollars per share)	$ (1.77)	$ 1.57	$ (1.97)
Weighted average common shares outstanding—diluted (shares)	44,243,317	38,141,793	27,854,912
Comprehensive income (loss):
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities, net of tax	(221)	(103)	222
Comprehensive income (loss)	$ (78,706)	$ 59,234	$ (54,567)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (shares) at Dec. 31, 2018		27,772,600
Beginning balance at Dec. 31, 2018	$ 102,862	$ 3	$ 169,784	$ (119)	$ (66,806)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options (shares)		110,156
Issuance of common stock upon exercise of stock options	255		255
Issuance of common stock (shares)		10,581
Issuance of common stock	24		24
Stock-based compensation expense	5,991		5,991
Portion of convertible note payable proceeds allocated to    beneficial conversion feature	2,101		2,101
Unrealized gain on marketable securities	222			222
Net income (loss)	(54,789)				(54,789)
Ending balance at Dec. 31, 2019	56,666	$ 3	178,155	103	(121,595)
Ending balance (shares) at Dec. 31, 2019		27,893,337
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options (shares)		223,895
Issuance of common stock upon exercise of stock options	802		802
Issuance of common stock under stock purchase plan (shares)		89,172
Issuance of common stock under stock purchase plan	194		194
Issuance of common stock (shares)		11,218,593
Issuance of common stock	29,086	$ 1	29,085
Conversion of redeemable convertible preferred stock to common stock (in shares)		1,282,050
Issuance of common stock upon conversion of convertible note payable	2,000		2,000
Stock-based compensation expense	7,765		7,765
Unrealized gain on marketable securities	(103)			(103)
Net income (loss)	59,337				59,337
Ending balance at Dec. 31, 2020	$ 155,747	$ 4	218,001	0	(62,258)
Ending balance (shares) at Dec. 31, 2020	40,707,047	40,707,047
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options (shares)		508,720
Issuance of common stock upon exercise of stock options	$ 2,022		2,022
Issuance of common stock upon vesting of RSUs (shares)		997,400
Issuance of common stock under stock purchase plan (shares)		46,899
Issuance of common stock under stock purchase plan	266		266
Issuance of common stock (shares)		3,737,172
Issuance of common stock	29,525	$ 1	29,524
Conversion of redeemable convertible preferred stock to common stock (in shares)		961,538
Issuance of common stock upon conversion of convertible note payable	1,500		1,500
Stock-based compensation expense	8,546		8,546
Unrealized gain on marketable securities	(221)			(221)
Net income (loss)	(78,485)				(78,485)
Ending balance at Dec. 31, 2021	$ 118,900	$ 5	$ 259,859	$ (221)	$ (140,743)
Ending balance (shares) at Dec. 31, 2021	46,958,776	46,958,776

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Adjustments to reconcile net loss to net cash provided by (used in) operating    activities:
Depreciation and amortization expense	1,569	1,670	1,785
Stock-based compensation expense	8,546	7,765	5,991
Non-cash interest expense related to note payable	1,069	1,650	74
Net amortization of premiums and discounts on marketable securities	807	(47)	(764)
Loss on disposal of property and equipment	0	1	1
Non-cash operating lease cost	2,041	1,950	1,814
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,653	(32)	3,001
Unbilled receivable	518	(2,571)	0
Other assets	74	(431)	12
Accounts payable	(226)	(2,716)	583
Accrued expenses and other current liabilities	2,307	2,436	(710)
Operating lease liability	(2,217)	(423)	(1,778)
Deferred revenue - related party	0	(38,592)	(15,360)
Net cash provided by (used in) operating activities	(62,344)	29,997	(60,140)
Cash flows from investing activities:
Purchases of property and equipment	(120)	(43)	(1,538)
Purchases of marketable securities	(111,632)	(650)	(118,347)
Proceeds from sales or maturities of marketable securities	12,500	59,000	136,850
Net cash provided by (used in) investing activities	(99,252)	58,307	16,965
Cash flows from financing activities:
Proceeds from issuance of convertible note payable, net of issuance costs	10,687	10,000	7,217
Payments of debt issuance costs	0	0	(81)
Proceeds for issuance of common stock, net	29,525	29,086	24
Proceeds from employee stock purchases	266	194	0
Proceeds from exercise of stock options	2,022	802	255
Net cash provided by financing activities	42,500	40,082	7,415
Net increase (decrease) in cash and cash equivalents and restricted cash	(119,096)	128,386	(35,760)
Cash and cash equivalents and restricted cash at beginning of period	176,736	48,350	84,110
Cash and cash equivalents and restricted cash at end of period	57,640	176,736	48,350
Supplemental disclosure of cash flow information:
Cash paid for interest	1,406	1,052	0
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and    accrued expenses	436	1,006	0
Additional right-of-use asset and related lease liability	0	15,003	0
Conversion of note payable into shares of common stock	$ 1,500	$ 2,000	$ 0

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Surface Oncology, Inc. (the “Company” or “Surface”) is a clinical-stage immuno-oncology company focused on using its specialized knowledge of the biological pathways critical to the immunosuppressive tumor microenvironment (“TME”) for the development of next-generation cancer therapies. Surface was incorporated in April 2014 under the laws of the State of Delaware. The Company is subject to risks common to early-stage companies in the biotechnology industry including, but not limited to, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the ability to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. On May 1, 2019, the Company entered into a Capital on Demand ™ Sales Agreement (the “2019 Sales Agreement”) with JonesTrading Institutional Services LLC (“JonesTrading”) to issue and sell shares of the Company’s common stock of up to $30,000 in gross proceeds, from time to time during the term of the a Sales Agreement, through an “at-the-market” equity offering program under which JonesTrading will act as the Company’s agent and/or principal (the “2019 ATM Facility”). The 2019 ATM Facility provides that JonesTrading will be entitled to compensation for its services in an amount of up to 3.0% of the gross proceeds of any shares sold under the 2019 ATM Facility. The Company has no obligation to sell any shares under the 2019 ATM Facility and may, at any time, suspend solicitation and offers under the 2019 Sales Agreement. As of December 31, 2021, the Company has sold 11,229,174 shares under the 2019 ATM Facility for net proceeds of $29,110. As of May 22, 2020, the Company had fully utilized and closed the 2019 ATM Facility. On May 22, 2020, the Company entered into a Capital on Demand™ Sales Agreement (the “2020 Sales Agreement”) with JonesTrading to issue and sell shares of the Company’s common stock of up to $50,000 in gross proceeds, from time to time during the term of the 2020 Sales Agreement, through an “at-the-market” equity offering program under which JonesTrading will act as the Company’s agent and/or principal (the “2020 ATM Facility”). The 2020 ATM Facility provides that JonesTrading will be entitled to compensation for its services in an amount of up to 3.0% of the gross proceeds of any shares sold under the 2020 ATM Facility. The Company has no obligation to sell any shares under the 2020 ATM Facility and may, at any time, suspend solicitation and offers under the 2020 Sales Agreement. As of December 31, 2021, the Company has sold 2,303,545 shares of common stock at-the-market under the 2020 ATM Facility for net proceeds of $19,479. As of August 5, 2021, the Company had closed the 2020 ATM Facility. On August 5, 2021, the Company entered into Amendment No. 1 to Capital on Demand TM Sales Agreement (the “Amended Sales Agreement”) with JonesTrading, which amends the 2020 Sales Agreement to allow the issuance and sale of up to $80,000 in gross proceeds, from time to time during the term of the Amended Sales Agreement, through an “at-the-market” equity offering program under which JonesTrading will act as the Company’s sales agent ("the 2021 ATM Facility"). The 2021 ATM Facility provides that JonesTrading will continue to be entitled to compensation for its services in an amount of up to 3.0% of the gross proceeds of any shares sold under the 2021 ATM Facility. The Company has no obligation to sell any shares under the Amended Sales Agreement and may, at any time, suspend solicitation and offers under the 2021 ATM Facility. As of December 31, 2021, the Company has sold 1,433,627 shares of common stock at-the-market under the 2021 ATM Facility for net proceeds of $10,046. The Company’s 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. The Company has primarily funded its operations with proceeds from private and public sales of its securities, proceeds from a collaboration agreement with Novartis, a license agreement with GSK, and issuance of a debt facility with K2 Health Ventures. The Company has incurred losses and negative cash flows from operations since its inception, including net losses of $78,485 and $54,789 for the years ended December 31, 2021 and 2019, respectively. The Company earned income of $59,337 for the year ended December 31, 2020, primarily related to revenue recognized under the GSK Agreement. As of December 31, 2021 and 2020, the Company had an accumulated deficit of $140,743 and $62,258, respectively. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. As of March 2, 2022, the issuance date of the consolidated financial statements for the year ended December 31, 2021, the Company expects that its cash and cash equivalents and marketable securities will be sufficient to fund its operating expenses, capital expenditure requirements and debt service obligations for at least the next 12 months. The future viability of the Company beyond that date is dependent on its ability to raise additional capital to finance its operations. The Company will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and 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 required to delay, reduce, or eliminate research and development programs, product portfolio expansion, or future commercialization efforts, which could adversely affect its business prospects. Although management continues to pursue these 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. The ongoing global outbreak of the novel coronavirus disease (“COVID-19”) has resulted in significant governmental measures being implemented to control the spread of the virus and while the Company cannot predict their scope or the severity of the outbreak, these developments and measures could materially and adversely affect the Company's business, the Company's results of operations and financial condition. The Company is closely monitoring the impact of the COVID-19 pandemic on all aspects of its business and has taken steps to minimize its impact on the Company's business. Although COVID-19 has not had a material adverse impact on the Company's operations and its clinical and preclinical programs, the extent to which COVID-19 ultimately impacts the Company's business, results of operations or financial condition will depend on future developments which are highly uncertain and cannot be predicted with confidence, such as the duration of the outbreak, new information that may emerge concerning the severity of COVID-19 or the effectiveness of actions taken to contain the pandemic or mitigate its impact, among others. Certain of the Company's third-party service providers have experienced shutdowns or other business disruptions. As a result, the Company's ability to conduct its business in the manner and on the timelines presently planned could be materially or negatively affected, which could have a material adverse impact on the Company's business, results of operations and financial condition.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiary, Surface Securities Corporation, a Massachusetts corporation, after elimination of all intercompany accounts and transactions. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from the Company’s estimates. Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at the acquisition date to be cash equivalents. Cash equivalents, which consist of money market funds are stated at fair value. Marketable Securities Marketable securities consist of investments with original maturities greater than 90 days at their acquisition date. The Company has classified its investments with maturities beyond one year as current, based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. The Company classifies all of its marketable securities as available-for-sale securities. The Company’s marketable securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale debt securities are reported as accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity. The cost of debt securities sold is determined on a specific identification basis, and realized gains and losses are included in interest and other income (expense), net in the consolidated statements of operations and comprehensive income (loss). The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Restricted Cash At December 31, 2021 and 2020, restricted cash consisted of cash deposited in a separate bank account as collateral for the Company’s facilities lease obligations. At December 31, 2021 and 2020, $1,595 of restricted cash was classified as non-current. Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash, cash equivalents and marketable securities. The Company maintains its cash, cash equivalents, and marketable securities at two accredited financial institution in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply products for research and development activities of its programs, including preclinical testing. These programs could be adversely affected by a significant interruption in the supply of such drug substance products. Fair Value of Financial Instruments 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 Company’s cash equivalents and marketable securities are carried at fair value, determined according to the fair value hierarchy described above. The carrying values of the Company’s prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. 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 useful life of the asset. Laboratory equipment is depreciated over five years. Computer equipment and furniture and office equipment are depreciated over three years. Leasehold improvements are amortized over the shorter of the lease term or 10 years. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation and amortization of assets disposed of are removed from the accounts, and any resulting gain or loss is included in income (loss) from operations. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment and right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount 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 forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. To date, the Company has not recorded any impairment losses on long-lived assets. Revenue Recognition We account for revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. In accordance with ASC Topic 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity 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 Topic 606, it 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 within the contract; and v. recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it 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 the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and/or research and development services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and 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. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded for deferred revenue. Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s balance sheet. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, non-current. The Company’s revenue arrangements include the following: Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty.) The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when 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 revenue related to sales-based royalties or milestone payments based on the level of sales. The Company’s revenues have been generated through our collaboration agreement with Novartis and license agreement with GSK. See Note 8, “Collaboration and License Agreements” for additional details regarding the Company’s collaboration and license agreements. Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses include salaries, stock-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company’s research and development activities, including allocated facility-related expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials. Research Contract Costs and Accruals The Company has entered into various research and development contracts with research institutions and other companies. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Nonrefundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered or the services rendered. 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 in the accompanying statements of operations and comprehensive loss. Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock options and restricted stock awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. Following the Company’s adoption of ASU 2018-7, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-7”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the related service period. The Company classifies stock-based compensation expense in its statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated using the Black- Scholes option-pricing model. The Company has historically been a private company and lacks 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 companies. 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 risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield 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 Company elects to account for forfeitures as they occur rather than apply an estimated forfeiture rate to share based payment expense. Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use (“ROU”) asset, operating lease liability, and operating lease liability, non-current in the Company’s consolidated balance sheets. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Many lease agreements include the option to renew or extend the lease term. The exercise of lease renewal options or extensions is at the Company’s sole discretion, and are only included in the calculation of the operating lease ROU asset and operating lease liability when it is reasonably certain that the Company would exercise such options. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, which it calculates based on the credit quality of the Company, and by comparing interest rates available in the market for similar borrowings, and adjusting this amount based on the impact of collateral over the term of each lease. The components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available to entities. Entities electing the practical expedient would not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company’s facilities operating leases have lease and non-lease components to which the Company has elected to apply the practical expedient and account for each lease component and related non-lease component as one single component. The Company also elected the package of practical expedients, which, among other things, allows the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. The Company also made an accounting policy election not to recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations and comprehensive loss over the lease term. Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making decisions. The Company’s singular focus is using its specialized knowledge of the biological pathways critical to the TME for the development of next-generation cancer therapies. All of the Company’s tangible assets are held in the United States, and all revenue is derived from the Company’s two collaboration partners, both of which are in the United States. Income Taxes The Company accounts for income taxes under 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 financial statements or in the Company's tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years 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 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 analyzing carryback capacity in periods with taxable income, reversal of existing taxable temporary differences and 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 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 financial statements. The amount of 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, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. Comprehensive Income (Loss) Comprehensive income (loss) includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive income (loss) in all periods presented was unrealized gains (losses) on marketable securities. 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 attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) attributable to common stockholders is computed by adjusting net income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including the assumed conversion of the Company’s convertible note payable and outstanding options to purchase common stock, except where the results would be anti-dilutive. 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 shares of common stock outstanding for the period, including potential dilutive common shares assuming the dilutive effective of the conversion of the convertible note payable and outstanding options to purchase common stock. In the diluted net income (loss) per share calculation, net income (loss) would also be adjusted for the elimination of interest expense on the convertible note payable (which includes amortization of the discount created for the beneficial conversion feature), if the impact was not anti-dilutive. For purpose of this calculation, outstanding options to purchase common stock or redeemable convertible preferred stock are considered potential dilutive common shares. Recently Issued Accounting Pronouncements 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 may result in earlier recognition of credit losses. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which narrowed the scope and changed the effective date for non-public entities for ASU 2016-13. The FASB subsequently issued supplemental guidance within ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05") . ASU 2019-05 provides an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. For public entities that are Securities and Exchange Commission filers, excluding entities eligible to be smaller reporting companies, ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, ASU 2016-13 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. This standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements and related disclosures. Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities As of December 31, 2021, the fair value of available-for-sale marketable securities by type of security was as follows: December 31, 2021 Amortized Gross Gross Fair Marketable debt securities: U.S. Treasury notes $ 77,550 $ — $ (188) $ 77,362 U.S. government agency bonds 20,775 — (33) $ 20,742 $ 98,325 $ — $ (221) $ 98,104 The amortized cost and fair value of the Company’s available-for-sale securities by contractual maturity are summarized as follows: December 31, 2021 Amortized Fair Maturing in one year or less $ 60,462 $ 60,406 Maturing in more than one year 37,863 $ 37,698 $ 98,325 $ 98,104 As of December 31, 2020, there were no available-for-sale marketable debt securities. The cost of securities sold is determined based on the specific identification method for purposes of recording realized gains and losses. During the year ended December 31, 2021, there were no realized losses on sales of marketable securities. During the years ended December 31, 2020 and 2019 realized gain on sales of marketable securities were $12 and $7, respectively. There were no marketable securities that required adjustment for other-than-temporary declines in fair value during the years ended December 31, 2021, 2020, and 2019.

Fair Value of Financial Assets

Fair Value of Financial Assets	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets	Fair Value of Financial Assets The following tables present information about the Company’s financial assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of December 31, 2021 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 20,309 $ — $ — $ 20,309 Marketable securities: U.S. Treasury notes — 77,362 — 77,362 U.S. government agency bonds — 20,742 — 20,742 $ 20,309 $ 98,104 $ — $ 118,413 Fair Value Measurements as of December 31, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 139,266 $ — $ — $ 139,266 $ 139,266 $ — $ — $ 139,266 As of December 31, 2021 and 2020, the Company’s cash equivalents were invested in money market funds and were valued based on Level 1 inputs. As of December 31, 2021, the Company’s marketable securities consisted of U.S. Treasury notes and U.S. government agency bonds and were valued based on Level 2 inputs. In determining the fair value of its U.S. Treasury notes and U.S. government agency bonds, the Company relied on quoted prices for similar securities in active markets or other inputs that are observable or can be corroborated by observable market data. During the years ended December 31, 2021 and 2020, there were no transfers between Level 1, Level 2 and Level 3.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net consisted of the following: Year Ended December 31, 2021 2020 Laboratory equipment $ 3,653 $ 3,601 Leasehold improvements 7,638 7,638 Computer equipment 702 535 Furniture and office equipment 1,074 1,074 Construction in process 337 — 13,404 12,848 Less: Accumulated depreciation and amortization (7,753) (6,184) $ 5,651 $ 6,664

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	Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following: Year Ended December 31, 2021 2020 Prepaid expenses $ 2,432 $ 2,797 Unbilled receivable 518 2,571 Interest receivable on marketable securities 247 — $ 3,197 $ 5,368

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: Year Ended December 31, 2021 2020 Accrued external research and development costs $ 5,316 $ 4,017 Accrued payroll and payroll-related costs 4,180 5,056 Accrued professional fees 355 327 Other 3,238 1,048 $ 13,089 $ 10,448

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration and License Agreements	Collaboration and License Agreements Collaboration Agreement with Novartis In January 2016, the Company entered into a collaboration agreement with Novartis (the “Novartis Agreement”), which was subsequently amended in May 2016, July 2017, September 2017, and October 2018. Pursuant to the Novartis Agreement, the Company granted Novartis a worldwide exclusive license to research, develop, manufacture and commercialize antibodies that target cluster of differentiation 73 ("CD73"). In addition, the Company initially granted Novartis the right to purchase exclusive option rights (each an “Option”) for up to four specified targets (each an “Option Target”) including certain development, manufacturing and commercialization rights. Novartis initially had the right to exercise up to three purchased Options. Under the Novartis Agreement, therefore, Novartis had the ability to exclusively license the development and manufacturing rights for up to four targets (inclusive of CD73). In January 2020, Novartis did not purchase and exercise its single remaining Option under the Novartis Agreement and, as a result, the option purchase period expired. Therefore, there are no Options remaining eligible for purchase, and potential exercise, and the Company’s performance obligations under the Novartis Agreement have ended. Under the Novartis Agreement, the Company is currently entitled to potential development milestones of $325,000 and sales milestones of $200,000, as well as tiered royalties on annual net sales by Novartis ranging from high single-digit to mid-teens percentages upon the successful commercialization of NZV930 (formerly SRF373). Novartis is a related party because it is a greater than 5% stockholder of the Company. During the years ended December 31, 2021 and 2020, the Company made no cash payments to Novartis related to the Novartis Agreement. Termination Unless terminated earlier, the Novartis Agreement will continue in effect until neither the Company nor Novartis is researching, developing, manufacturing or commercializing NZV930. Novartis may terminate the Novartis Agreement for any reason upon prior notice to the Company within a specified time period. Either party may terminate the Novartis Agreement in full if an undisputed material breach is not cured within a certain period of time or upon notice of insolvency of the other party. To the extent Novartis terminates for convenience, or the Company terminates for Novartis’ material breach, Novartis will grant the Company, on mutually agreeable financial terms, an exclusive, worldwide, irrevocable, perpetual and royalty-bearing license with respect to intellectual property controlled by Novartis that is reasonably necessary to research, develop, manufacture or commercialize NZV930. Revenue Recognition - Collaboration Revenue – Related Party In determining the appropriate amount of revenue to be recognized under ASC 606, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined 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 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. Under ASC 606, the Company recognized revenue using the cost-to-cost method, which it believes best depicts the transfer of control to the customer. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Under ASC 606, the estimated transaction price will include variable consideration. The Company does not include variable consideration to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will occur when any uncertainty associated with the variable consideration is resolved. The estimate of the Company’s measure of progress and estimate of variable consideration to be included in the transaction price will be updated at each reporting date as a change in estimate. The amount related to the unsatisfied portion will be recognized as that portion is satisfied over time. Under ASC 606 the Company accounted for (i) the license it conveyed with respect to CD73; and (ii) its obligations to perform research on CD73 and other specified targets as a single performance obligation under the Novartis Agreement. Novartis’ right to purchase exclusive options to obtain certain development, manufacturing and commercialization rights were accounted for separately as they do not represent material rights, based on the criteria of ASC 606. Upon the exercise of any purchased option by Novartis, the contract promises associated with an Option Target would have used a separate cost-to-cost model for purposes of revenue recognition under ASC 606. In February 2019, Novartis notified the Company of its decision not to purchase the Option related to IL-27. Future costs associated with this target were removed from the estimated total costs in the cost-to-cost model. In January 2020, Novartis did not purchase and exercise its single remaining Option under the Novartis Agreement and, as a result, the option purchase period expired. Future costs associated with this target were removed from the estimated total costs in the cost-to-cost model. This resulted in the Company recognizing the remaining deferred revenue of $38,592 to collaboration revenue - related party in January 2020. For the years ended December 31, 2021, 2020, and 2019, the Company recognized the following totals of collaboration revenue – related party: Year Ended December 31, 2021 2020 2019 Collaboration revenue - related party $ — $ 38,592 $ 15,360 As there are no Options remaining eligible for purchase and exercise, the Company's performance obligations under the Novartis Agreement have ended. License Agreement with GSK In December 2020, the Company entered into a license agreement (as amended by the GSK Amendment (as defined below) the “GSK Agreement”) with GSK. Pursuant to the GSK Agreement, the Company granted GSK a worldwide exclusive, sublicensable license to develop, manufacture and commercialize antibodies that target the antibody GSK4381562 (formerly SRF813), targeting CD112R, also known as PVRIG (the “Licensed Antibodies”). GSK will be responsible for the development, manufacturing and commercialization of the Licensed Antibodies and a joint development committee will be formed to facilitate information sharing between the Company and GSK. Under the terms of the GSK Agreement, GSK is obligated to use commercially reasonable efforts to develop and commercialize the Licensed Antibodies. In August 2021, the Company entered into the first amendment to the GSK Agreement (the "GSK Amendment"). Pursuant to the GSK Amendment, the Company will provide additional transition and supply services related to the development and manufacturing of the Licensed Antibodies. Development, Manufacturing and Commercialization of Licensed Antibodies GSK has the sole right to develop, manufacturer and commercialize the Licensed Antibodies and corresponding licensed products worldwide. GSK is obligated to use commercially reasonable efforts to develop the Licensed Antibodies and corresponding licensed products. GSK is responsible for all costs and expenses of such development, manufacturing and commercialization and is obligated to provide the Company with updates on its development, manufacturing and commercialization activities through the joint development committee. Exclusivity During the term of the GSK Agreement, neither the Company, nor any affiliates, will research, develop, manufacture, or commercialize any alternative product. Financial Terms Under the terms of the agreement, GSK made a one-time upfront payment of $85,000 and is required to make additional payments to the Company for supply services and transition services initially estimated to be $4,314 and $950, respectively. The Company is eligible to receive up to $90,000 in clinical and $155,000 in regulatory milestones. In addition, the Company may receive up to $485,000 in sales milestone payments. The Company is also eligible to receive royalties on global net sales of any approved products based on the licensed antibodies, ranging in percentages from high single digits to mid-teens. Due to the uncertainty of pharmaceutical development and the historical failure rates generally associated with drug development, the Company may not receive any milestone payments or any royalty payments under the GSK Agreement. Termination Unless terminated earlier, the GSK Agreement expires on a licensed product-by-licensed product and country-by-country basis on the later of ten years from the date of first commercial sale or when there is no longer a valid patent claim or regulatory exclusivity covering such licensed product in such country. Either party may terminate the GSK Agreement for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. GSK may terminate the GSK Agreement for its convenience. The Company may terminate the GSK Agreement if GSK institutes certain actions related to the licensed patents or if GSK ceases development activities, other than for certain specified technical or safety reasons. In the event of termination, the Company would regain worldwide rights to the terminated program. Revenue Recognition – License-Related Revenue In determining the appropriate amount of revenue to be recognized under ASC 606, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined 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 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. The Company assessed the GSK Agreement in accordance with ASC 606 and concluded that GSK is a customer. The Company identified the following promises under the contract: (i) a worldwide exclusive, sublicensable license to develop, manufacture and commercialize the Licensed Antibodies; (ii) supplying Licensed Antibodies until an investigational new drug application is accepted by a regulatory authority (iii) transition services until an investigational new drug application is accepted by a regulatory authority; and (iv) participation on the joint development and joint patent committees. The Company assessed the above promises and determined that the worldwide exclusive, sublicensable license to develop, manufacture and commercialize the Licensed Antibodies is considered functional intellectual property and distinct from other promises under the contract. This functional license is distinct in the context of the GSK Agreement as GSK can benefit from the license on its own or together with other readily available resources. In addition, the supply and transition services are not complex or specialized, could be performed by another qualified third party, are not expected to significantly modify or customize the license to SRF813, and are expected to be performed only for a short period of time. The Company determined that the impact of participation on the joint development and joint patent committees was insignificant and had an immaterial impact on the accounting model. Based on these assessments, the Company identified three distinct performance obligations at the outset of the GSK Agreement. The Company determined the transaction price under ASC 606 at the inception of the GSK Agreement to be $90,264, consisting of the upfront payment of $85,000 plus $4,314 for supply of the Licensed Antibodies and $950 for the transition services. The Company evaluated how much variable consideration related to clinical and regulatory milestones to include in the transaction price using the most likely amount approach and concluded that no amount should be included in the transaction price due to the high degree of uncertainty and risk associated with these potential payments. The Company also determined that royalties and sales milestones relate solely to the licenses of intellectual property and are therefore excluded from the transaction price under the sales- or usage-based royalty exception of ASC 606. Revenue related to these royalties and sales milestones will only be recognized when the associated sales occur, and relevant thresholds are met. As noted above, the Company identified three performance obligations in the GSK Agreement: (i) the delivery of the worldwide exclusive, sublicensable license to develop, manufacture and commercialize the Licensed Antibodies; (ii) supply of Licensed Antibodies until an investigational new drug application is accepted by a regulatory authority; and (iii) transition services until an investigational new drug application is accepted by a regulatory authority. The selling price of each performance obligation in the GSK Agreement was determined based on the Company’s standalone selling price (“SSP”) with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The Company recognizes revenue for the license performance obligation at a point in time, that is upon transfer of the license to GSK. As control of the license was transferred on the effective date of December 16, 2020 and GSK could begin to use and benefit from the license, the Company recognized $85,000 of license-related revenue during the year ended December 31, 2020 under the GSK Agreement. The Company recognized the costs allocated to supply services and transition services over time. The Company transferred control of these services over time and GSK received and consumed the benefit over time as the Company performed the services. The Company re-evaluated the transaction price at the end of each reporting period and as uncertain events were resolved, or other changes in circumstances occur, adjusted its estimate of the transaction price as necessary. For the year ended December 31, 2021, the Company recognized $1,954 of license-related revenue for supply services and $733 of license-related revenue related to the transition services. For the year ended December 31, 2020, the Company recognized $2,570 of license-related revenue for supply services, which represented the costs incurred associated with the portion of goods that were immediately transferred upon execution of the GSK Agreement. An immaterial amount of the transition services was performed in the year ended December 31, 2020. In November 2021, GSK notified the Company it received clearance from the FDA for GSK4381562 to proceed into a first-in-human clinical trial and as a result the Company's performance obligations under the GSK Agreement have ended. No amount of the transaction price allocated to the performance obligations was partially unsatisfied, nor did the Company have a contract liability associated with the GSK Agreement as of December 31, 2021. For the years ended December 31, 2021, 2020 , and 2019 , the Company recognized the following totals of license-related revenue: Year Ended December 31, 2021 2020 2019 License-related revenue $ 2,687 $ 87,570 $ —

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock As of December 31, 2021 and 2020, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 150,000,000 shares of $0.0001 par value common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any, subject to the preferential dividend rights of any outstanding preferred stock. No dividends have been declared or paid by the Company through December 31, 2021. As of December 31, 2021 and 2020, the Company had reserved 32,934,776 and 22,728,991 shares, respectively, of common stock for the exercise of outstanding stock options, the vesting of restricted stock units, shares to be issued under the 2021 and 2020 ATM Facilities, shares to be issued upon the conversion of the Loan Agreement, as amended (defined below), and the number of shares remaining available for future grant under the Company’s 2018 Stock Option and Incentive Plan and 2018 Employee Stock Purchase Plan. Reserved for future issuance The Company has reserved for future issuance the following number of shares of common stock: As of December 31, 2021 2020 Options to purchase common stock 7,057,258 6,011,126 Shares available for future grant 783,873 664,544 RSU's issued and expecting to vest — 1,043,300 2018 Employee Stock Purchase Plan 1,084,476 724,305 Shares available for conversion of note payable 832,677 1,282,052 Shares available for ATM offering 23,176,492 13,003,664 Total reserved 32,934,776 22,728,991 In August 2021, the Company entered into the Amended Sales Agreement with JonesTrading, which amends the 2020 Sales Agreement to issue and sell up to $80,000 in shares of the Company's common stock from time to time. As of December 31, 2021, the Company has sold 1,433,627 shares of common stock at-the-market under the 2021 ATM Facility for net proceeds of $10,046. In May 2020, the Company entered into the 2020 Sales Agreement with JonesTrading to issue and sell shares up to $50,000 in shares of the Company's common stock from time to time. As of December 31, 2021, the Company has sold 2,303,545 shares of common stock at-the-market under the 2020 ATM Facility for net proceeds of $19,479. As of August 2021, the Company had closed the 2020 ATM Facility.

Stock-Based Awards

Stock-Based Awards	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Awards	Stock-Based Awards 2014 Stock Incentive Plan The Company’s 2014 Stock Incentive Plan (the “2014 Plan”) provides for the Company to grant incentive stock options or nonqualified stock options, restricted stock awards, unrestricted stock awards or restricted stock units to employees, directors and consultants of the Company. The 2014 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or their committee if so delegated, except that the exercise price per share of the stock options may not be less than 100% of the fair market value of a share of the Company’s common stock on the date of grant and the term of the stock options may not be greater than ten years. As of December 31, 2021 and 2020 all remaining shares available under the 2014 Plan were transferred to the 2018 Plan. 2018 Stock Option and Incentive Plan On April 3, 2018, the Company’s stockholders approved the 2018 Stock Option and Incentive Plan (the “2018 Plan”), which became effective on April 18, 2018, the date on which the registration statement for the Company’s initial public offering was declared effective. The 2018 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, non-employee directors and other key persons (including consultants). The number of shares initially reserved for issuance under the 2018 Plan was 1,545,454, plus the shares of common stock remaining available for issuance under the 2014 Plan, which shall be cumulatively increased on each January 1 by 4% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s board of directors or compensation committee of 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, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) under the 2018 Plan and the 2014 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan. As of December 31, 2021 and 2020, 783,873 shares and 664,544 shares were available for future issuance under the 2018 Plan, respectively. Stock options granted under the 2014 Plan and 2018 Plan to employees generally vest over four years and expire after ten years. The Company does not currently hold any treasury shares. Upon stock option exercise, the Company issues new shares and delivers them to the participant. Stock Option Valuation The assumptions that the Company used to determine the fair value of the stock options granted to employees and directors were as follows, presented on a weighted average basis: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.89 % 1.29 % 2.46 % Expected term (in years) 5.96 5.99 6.12 Expected volatility 83.87 % 71.34 % 73.62 % Expected dividend yield 0.0 % 0.0 % 0.0 % Stock Options The following table summarizes the Company’s stock option activity for the year ended December 31, 2021: Number of Weighted Weighted Aggregate (in years) Outstanding as of December 31, 2020 6,011,126 $ 5.55 7.28 $ 24,912 Granted 1,838,905 9.11 Exercised (508,720) 3.98 Forfeited (284,053) 5.56 Outstanding as of December 31, 2021 7,057,258 $ 6.59 6.98 $ 4,678 Options exercisable at December 31, 2021 4,678,355 $ 6.22 6.13 $ 3,683 Vested and expected to vest at December 31, 2021 7,057,258 $ 6.59 6.98 $ 4,678 The weighted average grant-date fair value per share of stock options granted during the years ended December 31, 2021 and 2020, was $6.41 and $2.11, respectively. The aggregate fair value of stock options vested during the years ended December 31, 2021 and 2020, was $10,864 and $6,742, 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, 2020, and 2019 was $1,887, $735, and $208 respectively. As of December 31, 2021, and 2020, there were outstanding stock options held by non-employees for the purchase of 276,570 and 253,971 shares of common stock, respectively, with service-based vesting conditions. Restricted Stock Units The Company has granted restricted stock units ("RSUs") with service-based vesting conditions. RSUs represent the right to receive shares of common stock upon meeting specified vesting requirements. Unvested shares of restricted common stock may not be sold or transferred by the holder. These restrictions lapse according to the service-based vesting conditions of each award. The table below summarizes the Company’s restricted stock unit activity since December 31, 2020: Number of Weighted Average Unvested restricted stock units as of December 31, 2020 1,043,300 $ 3.21 Granted — — Vested (997,400) 3.21 Forfeited (45,900) 3.18 Unvested restricted stock units as of December 31, 2021 — $ — The expense related to RSUs granted to employees was $1,103 for the year ended December 31, 2021. At December 31, 2021, there was no unrecognized compensation cost related to unvested restricted stock units. 2018 Employee Stock Purchase Plan On April 3, 2018, the Company’s stockholders approved the 2018 Employee Stock Purchase Plan (the “ESPP”), which became effective on April 18, 2018, the date on which the registration statement for the Company’s initial public offering was declared effective. A total of 256,818 shares of common stock were initially reserved for issuance under this plan. In addition, the number of shares of common stock that may be issued under the ESPP automatically increased on January 1, 2019, and shall increase each January 1 thereafter through January 1, 2028, by the lesser of (i) 1% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 and (ii) such lesser number of shares as determined by the administrator of the Company’s ESPP. As of December 31, 2021, a total of 1,084,476 shares of common stock were reserved for issuance under this plan. For the year ended December 31, 2021 and 2020, the Company issued 46,899 and 89,172 shares of common stock, respectively, under the ESPP. Inducement Plan In December 2021, the Company adopted the Company’s 2021 Inducement Plan (the “Inducement Plan”) pursuant to which the Company reserved 600,000 shares of common stock to be used exclusively for grants of equity-based awards to individuals who were not previously employees or directors of the Company, as an inducement material to the individual’s entry into employment with the Company within the meaning of Rule 5635(c)(4) of the Marketplace Rules of the Nasdaq Stock Market, Inc. The Inducement Plan provides for the grant of equity-based awards in the form of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, unrestricted stock awards, and dividend equivalent rights. The Inducement Plan was adopted by the Company without stockholder approval pursuant to Rule 5635(c)(4) of the Marketplace Rules of the Nasdaq Stock Market, Inc. To date, there have been no grants made pursuant to the Inducement Plan. Stock-Based Compensation The Company recorded stock-based compensation expense related to stock options, restricted stock awards, and the ESPP in the following expense categories of its statements of operations and comprehensive loss: Year Ended December 31, 2021 2020 2019 Research and development expenses $ 2,431 $ 2,826 $ 2,350 General and administrative expenses 6,115 4,939 3,641 $ 8,546 $ 7,765 $ 5,991 As of December 31, 2021, the Company had an aggregate of $11,075 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.36 years.

Debt

Debt	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt On November 22, 2019, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with K2 HealthVentures LLC (the “Lender”). The Lender agreed to make available to the Company term loans in an aggregate principal amount of up to $25,000 under the Loan Agreement. On October 1, 2021, the Company entered into a First Amendment to Loan and Security Agreement (the “Loan Amendment”) with the Lender, which amends the existing Loan Agreement. The Company plans to use the proceeds of the term loans to support clinical development as well as for working capital and general corporate purposes. The Loan Agreement provided a term loan commitment of $25,000 in three potential tranches: (i) a $7,500 term loan facility funded on November 22, 2019 (the “First Tranche Term Loan”), (ii) a $10,000 term loan facility funded on June 5, 2020 (the “Second Tranche Term Loan”), and (iii) a $7,500 term loan facility (the “Third Tranche Term Loan”). All three of these term loans had a maturity date of December 1, 2023. The Company was obligated to pay a final fee equal to 4.45% of the aggregate amount of the term loans funded, such payment to occur upon the earliest of (i) the maturity date, (ii) the acceleration of the term loans, and (iii) the prepayment of the term loans. The Lender had, at its option, the ability to convert any portion of no more than $4,000 of the then outstanding term loan amount and all accrued and unpaid interest thereon into shares of the Company’s common stock at a conversion price of $1.56 per share. The Company determined that the embedded conversion option was not required to be separated from the term loan. The embedded conversion option met the derivative accounting scope exception since the embedded conversion option is indexed to the Company’s own common stock and qualifies for classification within stockholders’ equity. The Company recognized a beneficial conversion feature of $2,101, which represents the difference between the commitment date stock price of $2.33 per share and the conversion price of $1.56 per share. The beneficial conversion feature was recorded as a discount on the term loan and is accreted to interest expense using the effective interest method over the term of the loan. In June 2020, the Company drew down the Second Tranche Term Loan and received an additional $10,000 in proceeds. The Company was permitted to make interest-only payments on the First Tranche Term Loan and the Second Tranche Term Loan until January 2022 in accordance with the terms of the Loan Agreement. In August 2020, the Lender elected to convert $2,000 of the outstanding term loan amount into 1,282,050 shares of the Company's common stock, in accordance with the Loan Agreement. In February 2021, the Lender elected to convert $1,500 of the outstanding term loan agreement into 961,538 shares of the Company's common stock, in accordance with the Loan Agreement. After the conversion, the outstanding principal balance was $14,000. In October 2021, the Loan and Security Agreement was amended. Under the Loan Amendment, the Lender made available to the Company term loans in an aggregate principal amount of up to $50,000, in three potential tranches: (i) a $25,000 term loan facility (including refinancing of the Company’s outstanding amounts under the Existing Loan Agreement) funded on October 1, 2021 (the "First Tranche Refinancing Term Loan"), (ii) up to a $15,000 term loan facility (the "Second Tranche Refinancing Term Loan"), and (iii) an up to $10,000 term loan facility (the "Third Tranche Refinancing Term Loan") (together the "Refinancing Term Loans"). All three of these tranches have a maturity date of October 1, 2025. Borrowings under all three tranches of the term loan facility bear interest at a floating per annum rate equal to the greater of (i) 8.50% and (ii) the sum of (A) the greater of (x) the prime rate last quoted in The Wall Street Journal (or a comparable replacement rate if The Wall Street Journal ceases to quote such rate) or (y) 3.25%, plus (B) 5.25%. The Company is permitted to make interest-only payments on the outstanding principal balance of the term loan for approximately nineteen months following the funding date. The interest-only period can be extended by an additional nine months, subject to the Company raising net cash proceeds from financing activities (including without limitation sales of the Company's securities and up-front or milestone payments pursuant to existing or new strategic partnerships), in an aggregate amount of at least $100,000. The term of the loan facility is 48 months, with repayment in monthly installments commencing at the end of the resulting interest-only period as outlined above through the end of the 48-month term. The Company is obligated to pay a final fees equal to (i) 4.25% of the aggregate amount of the term loans funded, such payment to occur upon the earliest of (a) the maturity date, (b) the acceleration of the term loans, and (c) the prepayment of the term loans and (ii) $779 on the earlier of December 1, 2023 or the prepayment of the term loans. The Company has the option to prepay all, but not less than all, of the outstanding principal balance of the term loans under the Loan Amendment. If the Company prepays all of the term loans prior to the maturity date, it will pay the Lender a prepayment penalty fee based on a percentage of the outstanding principal balance, equal to 5% if the payment occurs on or before 24 months after the initial funding date, 3% if the prepayment occurs more than 24 months after, but on or before 36 months after the initial funding date, or 1% if the prepayment occurs more than 36 months after the initial funding date. The Lender may, at its option, elect to convert any portion of no more than $4,500 of the then outstanding term loan amount and all accrued and unpaid interest thereon into shares of the Company’s common stock at a conversion price of (i) with respect to the first $500 converted, $1.56 per share and (ii) with respect to any additional amounts converted in excess of $500, $7.81 per share. The Company’s obligations under the Loan Amendment are secured by a first priority security interest in substantially all of its assets. The Loan Amendment contains customary representations, warranties and also includes customary events of default, including payment defaults, breaches of covenants, change of control and a material adverse effect clause. Upon the occurrence of an event of default, a default interest rate of an additional 5.00% per annum may be applied to the outstanding loan balances, and the Lender may declare all outstanding obligations immediately due and payable and exercise all of its rights and remedies as set forth in the Loan Amendment and under applicable law. The Loan Amendment has been accounted for as a debt modification; as such, the financing costs of $313 has been reflected as additional debt discount and is amortized as an adjustment to interest expense over the term of the Loan Amendment. The Company recorded interest expense related to the loan facility of $2,546, $2,745, and $147 for the years ended December 31, 2021, 2020 and 2019, respectively. The fair value of the loan at December 31, 2021 approximates its face amount due to the floating interest rate. Future principal debt payments on the loan payable are as follows (in thousands): December 31, 2021 2022 $ — 2023 6,676 2024 9,604 2025 8,720 Total principal payments 25,000 Final fee due in 2023 779 Final fee due at maturity in 2025 1,063 Total principal payments and final fee 26,842 Unamortized debt discount and final fee 1,827 Note payable $ 25,015

Net Income (Loss) per Share

Net Income (Loss) per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Income (Loss) per Share	Net Income (Loss) per Share Basic and diluted net income (loss) per share attributable to common stockholders was calculated as follows: Year Ended December 31, 2021 2020 2019 Basic net income (loss) per share: Numerator: Net income (loss) $ (78,485) $ 59,337 $ (54,789) Denominator: Weighted average commons shares outstanding—basic 44,243,317 35,545,121 27,854,912 Net income (loss) per share—basic $ (1.77) $ 1.67 $ (1.97) Diluted net income (loss) per share: Numerator: Net income (loss) - basic $ (78,485) $ 59,337 $ (54,789) Interest expense on convertible note payable — 395 — Net income (loss) - diluted $ (78,485) $ 59,732 $ (54,789) Denominator: Weighted average commons shares outstanding—basic 44,243,317 35,545,121 27,854,912 Shares issuable upon conversion of convertible notes, as if converted — 1,282,052 — Dilutive effect of restricted stock units — 557,402 — Dilutive effect of common stock equivalents — 757,218 — Weighted average commons shares outstanding—diluted 44,243,317 38,141,793 27,854,912 Net income (loss) per share—diluted $ (1.77) $ 1.57 $ (1.97) The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per share for the year ended December 31, 2021, 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 above because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 Stock Options to purchase common stock 7,057,258 3,146,458 Shares to be issued under the ESPP 1,084,476 — RSUs issued and expected to vest — 2,400 Shares available from conversion of note payable 832,677 —

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2021
License Agreement [Abstract]
License Agreements	License Agreements Adimab Development and Option Agreement In October 2018, the Company and Adimab LLC (“Adimab”), entered into an amended and restated development and option agreement, (“the A&R Adimab Agreement”), which amended and restated the development and option agreement with Adimab dated July 2014, as amended, (“the Original Adimab Agreement”), for the discovery and optimization of proprietary antibodies as potential therapeutic product candidates. Under the A&R Adimab Agreement, the Company will select biological targets against which Adimab will use its proprietary platform technology to research and develop antibody proteins using a mutually agreed upon research plan. The A&R Adimab Agreement, among other things, extended the discovery term of the Original Adimab Agreement, provided access to additional antibodies, and expanded the Company’s right to evaluate and use antibodies that were modified or derived using Adimab technology for diagnostic purposes. Upon the Company’s selection of a target, the Company and Adimab will initiate a research plan and the discovery term begins. During the discovery term, Adimab will grant the Company a non-exclusive, non-sublicenseable license under its technology with respect to the target, to research, design and preclinically develop and use antibodies that were modified or derived using Adimab technology, solely to evaluate such antibodies, perform the Company’s responsibilities under the research plan, and use such antibodies for certain diagnostic purposes. The Company also will grant to Adimab a non-exclusive, nontransferable license with respect to the target under the Company’s technology that covers or relates to such target, solely to perform its responsibilities under the research plan during the discovery period. The Company is required to pay Adimab at an agreed upon rate for its full-time employees during the discovery period while Adimab performs research on each target under the applicable research plan. Adimab granted the Company an exclusive option to obtain a non-exclusive, worldwide, fully paid-up, sublicensable license under Adimab’s platform patents and other Adimab technology solely to research up to ten antibodies, chosen by the Company against a specific biological target for a specified period of time (the “Research Option”). In addition, Adimab granted the Company an exclusive option to obtain a worldwide, royalty-bearing, sublicensable license under Adimab platform patents and other Adimab technology to exploit, including commercially, 20 or more antibodies against specific biological targets (the “Commercialization Option”). Upon the exercise of a Commercialization Option, and payment of the applicable option fee to Adimab, Adimab will assign the Company the patents that cover the antibodies selected by such Commercialization Option. The Company will be required to use commercially reasonable efforts to develop, seek market approval of, and commercialize at least one antibody against the target covered by the Commercialization Option in specified markets upon the exercise of a Commercialization Option. Under the agreement, the Company is obligated to make milestone payments and to pay specified fees upon the exercise of the Research or Commercialization Options. During the discovery term, the Company may be obligated to pay Adimab up to 250 for technical milestones achieved against each biological target. Upon exercise of a Research Option, the Company is obligated to pay a nominal research maintenance fee on each of the next four anniversaries of the exercise. Upon the exercise of each Commercialization Option, the Company will be required to pay an option exercise fee of a low seven-digit dollar amount, and the Company may be responsible for milestone payments of up to an aggregate of $13,000 for each licensed product that receives marketing approval. For any licensed product that is commercialized, the Company is obligated to pay Adimab tiered royalties of a low to mid single-digit percentage on worldwide net sales of such product. The Company may also partially exercise a Commercialization Option with respect to ten antibodies against a biological target by paying 65% of the option fee and later either (i) paying the balance and choosing additional antibodies for commercialization, up to the maximum number under the Commercialization Option, or (ii) foregoing the Commercialization Option entirely. For any Adimab diagnostic product that is used with or in connection with any compound or product other than a licensed antibody or licensed product, the Company is obligated to pay Adimab up to a low seven digits in regulatory milestone payments and low single-digit royalties on net sales. No additional payment is due with respect to any companion diagnostic or any diagnostic product that does not contain any licensed antibody. Any payments payable to Adimab as a result of any product candidates being developed pursuant to the GSK Agreement, will be payable to Adimab directly by GSK. The A&R Adimab Agreement will remain in effect until (a) the earlier of (i) the expiration of the Research and Commercialization Options (if they expire without exercise) and (ii) 12 months from the effective date without the Company providing materials that pass Adimab’s quality control; or (b) if a Research Option is exercised but the Commercialization Option is not, then upon the expiration of the last to expire research license term; or (c) upon commercialization of a product, until the end of the royalty term, which will vary on a product-by-product and country-by-country basis, ending on the later of (y) the expiration of the last valid claim covering the licensed product in such country as the product is manufactured or sold, or (z) ten after the first commercial sale of the licensed product in such country. Either party may terminate the A&R Adimab Agreement for material breach if such breach remains uncured for a specified period of time, however, if a Research Option or Commercialization Option has been exercised and the breach only applies to the applicable target of such Research Option or Commercialization Option, then the termination right will only apply to such target. The Company may also terminate the A&R Adimab Agreement for any reason with prior notice to Adimab. If Adimab is bankrupt, the Company will be entitled to a complete duplicate of, or complete access to, all rights and licenses granted under or pursuant to the A&R Adimab Agreement. During the years ended December 31, 2021, 2020, and 2019, the Company recognized research and development expense under the agreement of $3,000, $3,092, and $1,175, respectively. Memorial Sloan Kettering Cancer Center License Agreement In November 2020, the Company and Memorial Sloan Kettering Cancer Center ("MSK") entered into a license agreement (the "MSK Agreement"). Under the agreement, MSK granted the Company a non-exclusive license to certain U.S. patent rights relating to methods of treating cancer with CCR8 antibodies to research, develop, make, use, sell, offer for sale, and import CCR8 antibodies intended to treat cancer. Under the terms of the MSK Agreement the upfront license execution fee due to MSK was $100. Half of the execution fee was due to MSK upon signature of the agreement, with the remaining portion due on the first anniversary. Under the MSK Agreement, each of these CCR8 antibodies is a licensed product and the Company is obligated to make milestone payments of up to an aggregate of $7,500 for each licensed product, as well as reimburse MSK for a portion of past and future patent-related expenses. For any licensed product that is commercialized, the Company is obligated to pay MSK a low single-digit percentage royalty on net U.S. sales of such product. The MSK License will remain in effect on a licensed product-by-licensed product basis until the later of when there is no longer a valid patent claim covering the composition, manufacture or use of such licensed product or 10 years from the date of first commercial sale of such licensed product in the U.S. The Company may terminate the MSK License for any reason with thirty days prior written notice to MSK. MSK may terminate the MSK License immediately upon written notice if the Company is convicted of a felony relating to the manufacture, use or sale of a licensed product anywhere we may manufacture, use or sell the licensed product, or, with a specified notice period, in the event of the Company's insolvency, bankruptcy, or cessation of business operations. MSK may also terminate the MSK License for nonpayment of any fees, milestones or royalties if such payment(s) remain past due for a specified period of time, and for an uncured material breach. During the years ended December 31, 2021 and 2020, the Company recognized research and development expense under the agreement of $50 and $50. Vaccinex Exclusive Product License Agreement In March 2021, the Company and Vaccinex entered into an exclusive product license agreement (the "Vaccinex License Agreement"), to exclusively license certain antibodies, including SRF114. Pursuant to the terms of the Vaccinex License Agreement, the Company has a worldwide, exclusive, sublicensable license to make, have made, use, sell, offer to sell, have sold, import, and otherwise exploit licensed products that incorporate certain Vaccinex intellectual property which covers certain antibodies, including the antibody SRF114 targeting CCR8, each a “Licensed Product.” Under the Vaccinex License Agreement, the Company is obligated to use commercially reasonable efforts to develop, clinically test, achieve regulatory approval, manufacture, market and commercialize at least one Licensed Product and have the sole right to develop, manufacture and commercialize the licensed products worldwide. The Company is responsible for all costs and expenses of such development, manufacturing and commercialization. Pursuant to the Vaccinex License Agreement, the Company paid Vaccinex a one-time fee of $850,000. Vaccinex is eligible to receive up to an aggregate of $3,500 based on achievement of certain clinical milestones and up to an aggregate of $11,500 based on achievement of certain regulatory milestones per Licensed Product. The Company also owes low single digit royalties on global net sales of any approved Licensed Products. Commencing on the third anniversary of the date of the Vaccinex License Agreement and continuing until the first dosing of a Licensed Product in a clinical trial, the Company will be required to pay Vaccinex a nominal yearly maintenance fee. The Company may terminate the Vaccinex License Agreement for convenience upon the notice period specified in the Vaccinex License Agreement. Either party may terminate the Vaccinex License Agreement for an uncured material breach by the other party. Vaccinex may terminate the Vaccinex License Agreement if the Company defaults on any payments owed to Vaccinex under the agreement, if the Company is in material breach of, and fail to cure, its development obligations, or institute certain actions related to the licensed patents. In the event of termination, all rights in the licensed intellectual property would revert to Vaccinex. During the years ended December 31, 2021, the Company recognized research and development expense under the Vaccinex License Agreement of $850.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Year Ended December 31, 2021 2020 2019 Income (loss) before taxes: Domestic $ (78,485) $ 59,346 $ (54,789) Foreign — — — Total income (loss) before income taxes $ (78,485) $ 59,346 $ (54,789) Income Taxes During the years ended December 31, 2021 and 2019, the Company recorded no income tax benefits for the net losses incurred or for the research and development tax credits generated in each year due to its uncertainty of realizing a benefit from those items. During the year ended December 31, 2020, the Company recorded no income tax expense or benefit for the net income incurred or for the research and development tax credits generated during the year due to the utilization of net operating loss carryforwards and the uncertainty of realizing a benefit from the credits. A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2021 2020 2019 Federal statutory income tax rate (21.0) % 21.0 % (21.0) % State taxes, net of federal benefit (12.5) % 6.3 % (6.2) % Stock-based compensation 0.2 % 0.5 % 1.0 % Research and development tax credits (5.0) % (3.2) % (7.9) % Change in deferred tax asset valuation allowance 38.1 % (24.5) % 33.7 % Other 0.2 % (0.1) % 0.4 % Effective income tax rate — % — % — % Significant components of the Company's deferred tax assets and liabilities as of December 31, 2021 and 2020 are as follows: December 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 30,313 $ 8,635 Research and development tax credit carryforwards 12,230 8,344 Intangible assets 1,812 1,235 Accrued expenses 1,422 — Stock-based compensation 5,237 3,911 Lease liability 8,808 9,428 Interest expense 269 — Other 180 — Total deferred tax assets 60,271 31,553 Valuation allowance (51,957) (21,961) Deferred tax assets 8,314 9,592 Deferred tax liabilities: Right-of-use asset (7,056) (7,625) Depreciation (1,150) (1,478) Beneficial conversion feature on convertible note payable (32) (397) Other (76) (92) Total deferred tax liabilities (8,314) (9,592) Net deferred tax assets $ — $ — As of December 31, 2021 and 2020, the Company had federal net operating loss carryforwards of $92,735 and $31,394, respectively, and state net operating loss carryforwards of $155,989 and $32,312, respectively, available to reduce future income tax liabilities. As of December 31, 2021 and 2020, the Company also had federal research and development tax credit carryforwards of $9,747 and $6,259, respectively, and state research and development tax credit carryforwards of $3,067 and $2,545, respectively, available to reduce future income tax liabilities. The federal net operating loss carryforwards do not expire and the state net operating loss carryforwards begin to expire in 2039. The federal and state research and development tax credit carryforwards begin to expire in 2034 and 2032, respectively. Utilization of the Company's net operating loss ("NOL") carryforwards and research and development ("R&D") credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred previously or that could occur in the future in accordance with Section 382 of the Internal Revenue Code of 1986 ("Section 382") as well as similar state provisions. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized annually to offset future taxable income and taxes, respectively. In general, an ownership change as defined by Section 382 results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. Since its formation, the Company has raised capital through the issuance of capital stock on several occasions. These financings, combined with the purchasing shareholders' subsequent disposition of those shares, could result in a change of control as defined by Section 382. The Company conducted an analysis under Section 382 to determine if historical changes in ownership through December 31, 2020 would limit or otherwise restrict its ability to utilize its NOL and R&D credit carryforwards. As a result of this analysis, the Company does not believe there are any significant limitations on its ability to utilize these carryforwards. However, future changes in ownership occurring after December 31, 2020 could affect the limitation in future years, and any limitation may result in expiration of a portion of the NOL or R&D credit carryforwards before utilization. As required by the provisions of ASC 740, management considers whether it is more likely than not that some portion or all of the net deferred tax assets will not be realized. Based upon the level of historical U.S. losses, management has determined that it is “more-likely-than-not” that the Company will not utilize the benefits of federal and state deferred tax assets for financial reporting purposes and, as a result, a full valuation allowance has been established at December 31, 2021 and 2020. The valuation allowance increase primarily relates to the Company's revenue recognition for tax purposes, and were as follows: Year Ended December 31, 2021 2020 2019 Valuation allowance at beginning of year $ (21,961) $ (36,535) $ (18,602) Increases recorded to income tax provision (30,616) (11,675) (17,933) Decreases recorded as a benefit to income tax provision 620 26,249 — Valuation allowance at end of year $ (51,957) $ (21,961) $ (36,535) The Company had no unrecognized tax benefits or related interest and penalties accrued for the years ended December 31, 2021 and 2020. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. The Company files 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's tax years are still open under statute from 2018 to present. All years may be examined to the extent the tax credit or net operating loss carryforwards are used in future periods. There are currently no federal or state audits.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	Leases The Company leases real estate, primarily its corporate headquarters in Cambridge, Massachusetts. The Company’s leases have remaining terms ranging from 1 year to 8 years. Certain leases include options to renew, exercised at the Company’s sole discretion, with renewal terms that can extend the lease five years. The Company evaluated the renewal options in its leases to determine if it was reasonably certain that the renewal option would be exercised, and therefore should be included in the calculation of the operating lease assets and operating lease liabilities. Given the Company’s current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that the renewal option related to its corporate headquarters would be exercised. However, for leases it determined the renewal option was probable to be exercised, the Company included the renewal period in the calculation of the operating lease right-of-use assets and operating lease liabilities. All of the Company’s leases qualify as operating leases. With the adoption of the new leasing standard, the Company has recorded a right-of-use asset and corresponding lease liability, by calculating the present value of future lease payments, discounted at either 9.5% or 10.5%, the Company’s incremental borrowing rates, over the expected term. The right-of-use asset is reduced by any lease incentives received and the legacy deferred rent balance. In May 2016, the Company entered into an operating lease agreement for its corporate headquarters in Cambridge, Massachusetts, with a ten-year term that expires in February 2027 (“Initial Space”). Rental payments related to the lease commenced in April 2017. In connection with this lease, the Company was entitled to cash incentives from the landlord to be used for the construction of leasehold improvements within the facility. As of January 1, 2019, the Company was entitled to $4,803 of such incentives, which were recorded as a reduction to the right-of-use asset and included as a straight-line reduction to lease expense over the lease term. In May 2018, the Company executed an amendment to lease an additional 33,526 square feet at 50 Hampshire Street in Cambridge, Massachusetts, with a 10-year term (“Expansion Space”). This additional space became available for occupancy on January 1, 2020 and rental payments related to the lease commenced in April 2020. In connection with this lease amendment, the Company is entitled to a landlord-provided tenant improvement allowance of up to $1,005 to be applied to the cost of the construction of leasehold improvements. The Company determined that it owns the leasehold improvements and, as such, reflected the $1,005 lease incentive as a reduction of the rental payments used to measure the operating lease liability, and, in turn, the operating lease right-of-use asset as of the lease commencement date. The components of the Company’s lease expense are as follows: Lease Costs Classification Year Ended December 31, 2021 Year Ended December 31, 2020 Year Ended December 31, 2019 Operating lease cost R&D Expense $ 2,000 $ 2,111 $ 2,312 G&A Expense 3,353 3,292 899 Variable lease costs (1) R&D Expense 641 585 707 G&A Expense 1,112 1,169 276 Total lease cost $ 7,106 $ 7,157 $ 4,194 Weighted-average remaining lease term (in months) 98.73 109.84 119.6 Weighted-average discount rate 10.5 % 10.5 % 10.5 % (1) Variable lease costs include certain additional charges for operating costs, including insurance, maintenance, taxes, utilities, and other costs incurred, which are billed based on both usage and as a percentage of the Company’s share of total square footage. Short term lease costs are immaterial. Cash paid for amounts included in the measurement of the Company’s operating lease liabilities was $7,916 and $6,608 for the years ended December 31, 2021 and 2020. As of December 31, 2021, the maturities of the Company’s operating lease liabilities were as follows: Year Ending December 31, 2022 $ 5,385 2023 5,413 2024 5,533 2025 5,656 2026 5,782 Thereafter 20,083 Total future lease payments 47,852 Less: Interest (15,559) Present value of future lease payments (lease liability) $ 32,293 Future minimum lease payments for the Company’s operating leases as of December 31, 2020 were as follows: Year Ending December 31, 2021 $ 5,529 2022 5,385 2023 5,413 2024 5,533 2025 5,656 Thereafter 25,865 $ 53,381 Sublease Agreement with EQRx, Inc. In December 2019, the Company entered into a sublease agreement with EQRx, Inc. to sublease the entire Expansion Space. The term of the sublease agreement commenced in January 2020 and ends on the last day of the 36th calendar month following rent commencement, with no option to extend. The annual rent for the subleased premises is greater than the annual rent owed by the Company to the landlord for the leased premises. The sublessee is obligated to pay all real estate taxes and costs related to the subleased premises, including cost of operations, maintenance, repair, replacement and property management. The Company concluded that the sublease is an operating lease. Consistent with the Company’s policy election for lessor operating leases, each lease component and its associated non-lease components is accounted for as a single lease component. As of December 31, 2021, future undiscounted cash inflows under the sublease are as follows: Year Ending December 31, 2022 $ 2,884 2023 241 $ 3,125 In the years ended December 31, 2021 and 2020, the Company recognized sublease income of $3,371 and $3,169, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Agreements The Company has entered into lease agreements under which it is obligated to make rental payments (see Note 15). Manufacturing and Research Agreements The Company has entered into agreements with external contract manufacturing organizations and contract research organizations engaged to manufacture clinical trial materials as well as to conduct discovery research and preclinical development activities. License Agreements The Company has entered into license agreements with various parties under which it is obligated to make contingent and non-contingent payments (see Note 13). Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, 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 and its officers 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 or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims under indemnification arrangements that would have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its financial statements as of December 31, 2021. 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 its legal proceedings.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Novartis Institutes for BioMedical Research, Inc. Novartis is a related party because it is a greater than 5% stockholder of the Company. In January 2016, the Company entered into the Novartis Agreement and sold 2,000,000 shares of its Series A-1 preferred stock to Novartis for gross proceeds of $13,500. In addition, concurrent with the Company’s initial public offering of common stock, the Company issued Novartis 766,666 shares of its common stock at $15.00 per share for proceeds of $11,500 in a private placement. During the year ended December 31, 2021, the Company did not receive any cash payments from Novartis. As of December 31, 2021 and 2020, no amounts were due from Novartis. During the years ended December 31, 2021, 2020 and 2019, the Company made no cash payments to Novartis related to the Novartis Agreement. Research Agreement with Vaccinex, Inc. On November 30, 2017, the Company entered into a research agreement (the "Vaccinex Research Agreement") with Vaccinex, whereby Vaccinex will use its technology to assist the Company with identifying and selecting experimental human monoclonal antibodies against targets selected by the Company. On March 23, 2021, the Company exercised its option under the Vaccinex Research Agreement to enter into the Vaccinex License Agreement to exclusively license certain antibodies generated under the Vaccinex Research Agreement. The Company's former Chief Executive Officer and current member of its board of directors is a member of the board of directors of Vaccinex. During the years ended December 31, 2021, 2020, and 2019, the Company paid Vaccinex an aggregate of $50, $50 and $606, respectively, relating to the Vaccinex Research Agreement. During the year ended December 31, 2021, the Company paid Vaccinex $850 relating to the Vaccinex License Agreement. The payments under the Vaccinex Research Agreement and the Vaccinex License Agreements were recognized as research and development expense during the years ended December 31, 2021, 2020, and 2019. No amounts were due by the Company to Vaccinex as of December 31, 2021 and 2020.

401(k) Savings Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
401(k) Savings Plan	401(k) Savings PlanThe Company has a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements. The Company matches 100% of employees’ contributions to the 401(k) Plan up to 3% of compensation and 50% of employees’ contributions to the 401(k) Plan for salary deferrals between 3% and 5% of compensation. The Company’s contributions made under the 401(k) Savings Plan for the years ended December 31, 2021, 2020, and 2019 totaled $403, $370, and $399, respectively.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiary, Surface Securities Corporation, a Massachusetts corporation, after elimination of all intercompany accounts and transactions.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from the Company’s estimates.
Cash Equivalents	Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at the acquisition date to be cash equivalents. Cash equivalents, which consist of money market funds are stated at fair value.
Marketable Securities	Marketable Securities Marketable securities consist of investments with original maturities greater than 90 days at their acquisition date. The Company has classified its investments with maturities beyond one year as current, based on their highly liquid nature and because such marketable securities represent the investment of cash that is available for current operations. The Company classifies all of its marketable securities as available-for-sale securities. The Company’s marketable securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale debt securities are reported as accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity. The cost of debt securities sold is determined on a specific identification basis, and realized gains and losses are included in interest and other income (expense), net in the consolidated statements of operations and comprehensive income (loss). The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary,” the Company reduces the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Restricted Cash	Restricted Cash At December 31, 2021 and 2020, restricted cash consisted of cash deposited in a separate bank account as collateral for the Company’s facilities lease obligations. At December 31, 2021 and 2020, $1,595 of restricted cash was classified as non-current.
Concentration of Credit Risk and of Significant Suppliers	Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk primarily consist of cash, cash equivalents and marketable securities. The Company maintains its cash, cash equivalents, and marketable securities at two accredited financial institution in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply products for research and development activities of its programs, including preclinical testing. These programs could be adversely affected by a significant interruption in the supply of such drug substance products.
Fair Value of Financial Instruments	Fair Value of Financial Instruments 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 Company’s cash equivalents and marketable securities are carried at fair value, determined according to the fair value hierarchy described above. The carrying values of the Company’s prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities.
Property and Equipment	Property and EquipmentProperty and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the useful life of the asset. Laboratory equipment is depreciated over five years. Computer equipment and furniture and office equipment are depreciated over three years. Leasehold improvements are amortized over the shorter of the lease term or 10 years. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation and amortization of assets disposed of are removed from the accounts, and any resulting gain or loss is included in income (loss) from operations
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment and right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount 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 forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. To date, the Company has not recorded any impairment losses on long-lived assets.
Revenue Recognition	Revenue Recognition We account for revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. In accordance with ASC Topic 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity 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 Topic 606, it 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 within the contract; and v. recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it 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 the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and/or research and development services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and 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. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded for deferred revenue. Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s balance sheet. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current portion of deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, non-current. The Company’s revenue arrangements include the following: Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty.) The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when 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 revenue related to sales-based royalties or milestone payments based on the level of sales.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses include salaries, stock-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company’s research and development activities, including allocated facility-related expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials.
Research Contract Costs and Accruals	Research Contract Costs and Accruals The Company has entered into various research and development contracts with research institutions and other companies. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Nonrefundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered or the services rendered.
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 in the accompanying statements of operations and comprehensive loss.
Stock-Based Compensation	Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock options and restricted stock awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. Following the Company’s adoption of ASU 2018-7, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-7”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the related service period. The Company classifies stock-based compensation expense in its statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated using the Black- Scholes option-pricing model. The Company has historically been a private company and lacks 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 companies. 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 risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield 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 Company elects to account for forfeitures as they occur rather than apply an estimated forfeiture rate to share based payment expense.
Leases	Leases The Company determines if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use (“ROU”) asset, operating lease liability, and operating lease liability, non-current in the Company’s consolidated balance sheets. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Many lease agreements include the option to renew or extend the lease term. The exercise of lease renewal options or extensions is at the Company’s sole discretion, and are only included in the calculation of the operating lease ROU asset and operating lease liability when it is reasonably certain that the Company would exercise such options. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, which it calculates based on the credit quality of the Company, and by comparing interest rates available in the market for similar borrowings, and adjusting this amount based on the impact of collateral over the term of each lease. The components of a lease are split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available to entities. Entities electing the practical expedient would not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company’s facilities operating leases have lease and non-lease components to which the Company has elected to apply the practical expedient and account for each lease component and related non-lease component as one single component. The Company also elected the package of practical expedients, which, among other things, allows the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. The Company also made an accounting policy election not to recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations and comprehensive loss over the lease term.
Segment Data	Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making decisions. The Company’s singular focus is using its specialized knowledge of the biological pathways critical to the TME for the development of next-generation cancer therapies. All of the Company’s tangible assets are held in the United States, and all revenue is derived from the Company’s two collaboration partners, both of which are in the United States.
Income Taxes	Income Taxes The Company accounts for income taxes under 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 financial statements or in the Company's tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years 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 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 analyzing carryback capacity in periods with taxable income, reversal of existing taxable temporary differences and 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 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 financial statements. The amount of 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, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive income (loss) in all periods presented was unrealized gains (losses) on marketable securities.
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 attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) attributable to common stockholders is computed by adjusting net income (loss) attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including the assumed conversion of the Company’s convertible note payable and outstanding options to purchase common stock, except where the results would be anti-dilutive. 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 shares of common stock outstanding for the period, including potential dilutive common shares assuming the dilutive effective of the conversion of the convertible note payable and outstanding options to purchase common stock. In the diluted net income (loss) per share calculation, net income (loss) would also be adjusted for the elimination of interest expense on the convertible note payable (which includes amortization of the discount created for the beneficial conversion feature), if the impact was not anti-dilutive. For purpose of this calculation, outstanding options to purchase common stock or redeemable convertible preferred stock are considered potential dilutive common shares.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements 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 may result in earlier recognition of credit losses. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which narrowed the scope and changed the effective date for non-public entities for ASU 2016-13. The FASB subsequently issued supplemental guidance within ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief ("ASU 2019-05") . ASU 2019-05 provides an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. For public entities that are Securities and Exchange Commission filers, excluding entities eligible to be smaller reporting companies, ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, ASU 2016-13 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. This standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements and related disclosures. Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security	As of December 31, 2021, the fair value of available-for-sale marketable securities by type of security was as follows: December 31, 2021 Amortized Gross Gross Fair Marketable debt securities: U.S. Treasury notes $ 77,550 $ — $ (188) $ 77,362 U.S. government agency bonds 20,775 — (33) $ 20,742 $ 98,325 $ — $ (221) $ 98,104
Summary of Available-for-sale Debt Securities by Contractual Maturity	The amortized cost and fair value of the Company’s available-for-sale securities by contractual maturity are summarized as follows: December 31, 2021 Amortized Fair Maturing in one year or less $ 60,462 $ 60,406 Maturing in more than one year 37,863 $ 37,698 $ 98,325 $ 98,104

Fair Value of Financial Assets

Fair Value of Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Summary of Financial Assets Measured at Fair Value on Recurring Basis	The following tables present information about the Company’s financial assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of December 31, 2021 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 20,309 $ — $ — $ 20,309 Marketable securities: U.S. Treasury notes — 77,362 — 77,362 U.S. government agency bonds — 20,742 — 20,742 $ 20,309 $ 98,104 $ — $ 118,413 Fair Value Measurements as of December 31, 2020 using: Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 139,266 $ — $ — $ 139,266 $ 139,266 $ — $ — $ 139,266

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment Net	Property and equipment, net consisted of the following: Year Ended December 31, 2021 2020 Laboratory equipment $ 3,653 $ 3,601 Leasehold improvements 7,638 7,638 Computer equipment 702 535 Furniture and office equipment 1,074 1,074 Construction in process 337 — 13,404 12,848 Less: Accumulated depreciation and amortization (7,753) (6,184) $ 5,651 $ 6,664

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]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: Year Ended December 31, 2021 2020 Prepaid expenses $ 2,432 $ 2,797 Unbilled receivable 518 2,571 Interest receivable on marketable securities 247 — $ 3,197 $ 5,368

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: Year Ended December 31, 2021 2020 Accrued external research and development costs $ 5,316 $ 4,017 Accrued payroll and payroll-related costs 4,180 5,056 Accrued professional fees 355 327 Other 3,238 1,048 $ 13,089 $ 10,448

Collaboration and License Agr_2

Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Collaboration Revenue	For the years ended December 31, 2021, 2020, and 2019, the Company recognized the following totals of collaboration revenue – related party: Year Ended December 31, 2021 2020 2019 Collaboration revenue - related party $ — $ 38,592 $ 15,360 For the years ended December 31, 2021, 2020 , and 2019 , the Company recognized the following totals of license-related revenue: Year Ended December 31, 2021 2020 2019 License-related revenue $ 2,687 $ 87,570 $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Summary of Shares of Common Stock Reserved for Future Issuance	The Company has reserved for future issuance the following number of shares of common stock: As of December 31, 2021 2020 Options to purchase common stock 7,057,258 6,011,126 Shares available for future grant 783,873 664,544 RSU's issued and expecting to vest — 1,043,300 2018 Employee Stock Purchase Plan 1,084,476 724,305 Shares available for conversion of note payable 832,677 1,282,052 Shares available for ATM offering 23,176,492 13,003,664 Total reserved 32,934,776 22,728,991

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Assumptions used to Determine Fair Value of Stock Options Granted to Employees and Directors	The assumptions that the Company used to determine the fair value of the stock options granted to employees and directors were as follows, presented on a weighted average basis: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.89 % 1.29 % 2.46 % Expected term (in years) 5.96 5.99 6.12 Expected volatility 83.87 % 71.34 % 73.62 % Expected dividend yield 0.0 % 0.0 % 0.0 %
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity for the year ended December 31, 2021: Number of Weighted Weighted Aggregate (in years) Outstanding as of December 31, 2020 6,011,126 $ 5.55 7.28 $ 24,912 Granted 1,838,905 9.11 Exercised (508,720) 3.98 Forfeited (284,053) 5.56 Outstanding as of December 31, 2021 7,057,258 $ 6.59 6.98 $ 4,678 Options exercisable at December 31, 2021 4,678,355 $ 6.22 6.13 $ 3,683 Vested and expected to vest at December 31, 2021 7,057,258 $ 6.59 6.98 $ 4,678
Summary of Restricted Stock Unit Activity	The table below summarizes the Company’s restricted stock unit activity since December 31, 2020: Number of Weighted Average Unvested restricted stock units as of December 31, 2020 1,043,300 $ 3.21 Granted — — Vested (997,400) 3.21 Forfeited (45,900) 3.18 Unvested restricted stock units as of December 31, 2021 — $ —
Summary of Stock-Based Compensation Expense Related to Stock Options, Restricted Stock Awards and ESPP	The Company recorded stock-based compensation expense related to stock options, restricted stock awards, and the ESPP in the following expense categories of its statements of operations and comprehensive loss: Year Ended December 31, 2021 2020 2019 Research and development expenses $ 2,431 $ 2,826 $ 2,350 General and administrative expenses 6,115 4,939 3,641 $ 8,546 $ 7,765 $ 5,991

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Future Principal Debt Payments on the Loan Payable	Future principal debt payments on the loan payable are as follows (in thousands): December 31, 2021 2022 $ — 2023 6,676 2024 9,604 2025 8,720 Total principal payments 25,000 Final fee due in 2023 779 Final fee due at maturity in 2025 1,063 Total principal payments and final fee 26,842 Unamortized debt discount and final fee 1,827 Note payable $ 25,015

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net income (loss) per share attributable to common stockholders was calculated as follows: Year Ended December 31, 2021 2020 2019 Basic net income (loss) per share: Numerator: Net income (loss) $ (78,485) $ 59,337 $ (54,789) Denominator: Weighted average commons shares outstanding—basic 44,243,317 35,545,121 27,854,912 Net income (loss) per share—basic $ (1.77) $ 1.67 $ (1.97) Diluted net income (loss) per share: Numerator: Net income (loss) - basic $ (78,485) $ 59,337 $ (54,789) Interest expense on convertible note payable — 395 — Net income (loss) - diluted $ (78,485) $ 59,732 $ (54,789) Denominator: Weighted average commons shares outstanding—basic 44,243,317 35,545,121 27,854,912 Shares issuable upon conversion of convertible notes, as if converted — 1,282,052 — Dilutive effect of restricted stock units — 557,402 — Dilutive effect of common stock equivalents — 757,218 — Weighted average commons shares outstanding—diluted 44,243,317 38,141,793 27,854,912 Net income (loss) per share—diluted $ (1.77) $ 1.57 $ (1.97)
Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders	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 above because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 Stock Options to purchase common stock 7,057,258 3,146,458 Shares to be issued under the ESPP 1,084,476 — RSUs issued and expected to vest — 2,400 Shares available from conversion of note payable 832,677 —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Income Before Income Taxes	Year Ended December 31, 2021 2020 2019 Income (loss) before taxes: Domestic $ (78,485) $ 59,346 $ (54,789) Foreign — — — Total income (loss) before income taxes $ (78,485) $ 59,346 $ (54,789)
Schedule of Reconciliation of Effective 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 December 31, 2021 2020 2019 Federal statutory income tax rate (21.0) % 21.0 % (21.0) % State taxes, net of federal benefit (12.5) % 6.3 % (6.2) % Stock-based compensation 0.2 % 0.5 % 1.0 % Research and development tax credits (5.0) % (3.2) % (7.9) % Change in deferred tax asset valuation allowance 38.1 % (24.5) % 33.7 % Other 0.2 % (0.1) % 0.4 % Effective income tax rate — % — % — %
Schedule of Components of Deferred Tax Assets and Liabilities	Significant components of the Company's deferred tax assets and liabilities as of December 31, 2021 and 2020 are as follows: December 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 30,313 $ 8,635 Research and development tax credit carryforwards 12,230 8,344 Intangible assets 1,812 1,235 Accrued expenses 1,422 — Stock-based compensation 5,237 3,911 Lease liability 8,808 9,428 Interest expense 269 — Other 180 — Total deferred tax assets 60,271 31,553 Valuation allowance (51,957) (21,961) Deferred tax assets 8,314 9,592 Deferred tax liabilities: Right-of-use asset (7,056) (7,625) Depreciation (1,150) (1,478) Beneficial conversion feature on convertible note payable (32) (397) Other (76) (92) Total deferred tax liabilities (8,314) (9,592) Net deferred tax assets $ — $ —
Summary of Changes in Valuation Allowance for Deferred Tax Assets	The valuation allowance increase primarily relates to the Company's revenue recognition for tax purposes, and were as follows: Year Ended December 31, 2021 2020 2019 Valuation allowance at beginning of year $ (21,961) $ (36,535) $ (18,602) Increases recorded to income tax provision (30,616) (11,675) (17,933) Decreases recorded as a benefit to income tax provision 620 26,249 — Valuation allowance at end of year $ (51,957) $ (21,961) $ (36,535)

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Summary of Components of Lease Expense	The components of the Company’s lease expense are as follows: Lease Costs Classification Year Ended December 31, 2021 Year Ended December 31, 2020 Year Ended December 31, 2019 Operating lease cost R&D Expense $ 2,000 $ 2,111 $ 2,312 G&A Expense 3,353 3,292 899 Variable lease costs (1) R&D Expense 641 585 707 G&A Expense 1,112 1,169 276 Total lease cost $ 7,106 $ 7,157 $ 4,194 Weighted-average remaining lease term (in months) 98.73 109.84 119.6 Weighted-average discount rate 10.5 % 10.5 % 10.5 % (1) Variable lease costs include certain additional charges for operating costs, including insurance, maintenance, taxes, utilities, and other costs incurred, which are billed based on both usage and as a percentage of the Company’s share of total square footage. Short term lease costs are immaterial.
Schedule of Maturities of Operating Lease Liabilities	As of December 31, 2021, the maturities of the Company’s operating lease liabilities were as follows: Year Ending December 31, 2022 $ 5,385 2023 5,413 2024 5,533 2025 5,656 2026 5,782 Thereafter 20,083 Total future lease payments 47,852 Less: Interest (15,559) Present value of future lease payments (lease liability) $ 32,293 Future minimum lease payments for the Company’s operating leases as of December 31, 2020 were as follows: Year Ending December 31, 2021 $ 5,529 2022 5,385 2023 5,413 2024 5,533 2025 5,656 Thereafter 25,865 $ 53,381
Schedule of Future Undiscounted Cash Inflows Under Sublease	As of December 31, 2021, future undiscounted cash inflows under the sublease are as follows: Year Ending December 31, 2022 $ 2,884 2023 241 $ 3,125

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) - USD ($)	Aug. 05, 2021	May 22, 2020	May 01, 2019	May 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Net proceeds from issuance of common stock					$ 29,525,000	$ 29,086,000	$ 24,000
Common stock, issued (shares)					46,958,776	40,707,047
Net income (loss)					$ (78,485,000)	$ 59,337,000	$ (54,789,000)
Accumulated deficit					$ (140,743,000)	$ (62,258,000)
Operating expenses and capital expenditure requirements (months)					12 months
2019 ATM Facility
Class of Stock [Line Items]
Net proceeds from issuance of common stock					$ 29,110,000
Common stock, issued (shares)					11,229,174
2020 A T M Facility
Class of Stock [Line Items]
Net proceeds from issuance of common stock					$ 19,479,000
Common stock, issued (shares)					2,303,545
2020 A T M Facility | Maximum
Class of Stock [Line Items]
Gross proceeds from issuance of common stock		$ 50,000,000		$ 50,000,000
Percentage of gross proceeds of shares sold for compensation		3.00%
2021 ATM Facility
Class of Stock [Line Items]
Net proceeds from issuance of common stock					$ 10,046,000
Common stock, issued (shares)					1,433,627
2021 ATM Facility | Maximum
Class of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 80,000,000				$ 80,000,000
Percentage of gross proceeds of shares sold for compensation	3.00%
JonesTrading Institutional Services LLC | 2019 ATM Facility | Maximum
Class of Stock [Line Items]
Gross proceeds from issuance of common stock			$ 30,000,000
Percentage of gross proceeds of shares sold for compensation			3.00%

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021USD ($)institutionpartner	Dec. 31, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Maximum maturity period of short-term, highly liquid investments for qualifying cash equivalents (days)	90 days
Minimum maturity period of investments for qualifying marketable securities (days)	90 days
Restricted cash, non-current	$ 1,595,000	$ 1,595,000
Number of accredited financial institution where cash, cash equivalents and marketable securities maintained | institution	2
Impairment losses on long-lived assets	$ 0
Number of collaboration partners | partner	2
Laboratory Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment depreciated or amortized over useful life (in years)	5 years
Computer equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment depreciated or amortized over useful life (in years)	3 years
Furniture and office equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment depreciated or amortized over useful life (in years)	3 years
Leasehold improvements
Summary Of Significant Accounting Policies [Line Items]
Property and equipment depreciated or amortized over useful life (in years)	10 years

Marketable Securities - Summary

Marketable Securities - Summary of Fair Value of Available-for-sale Marketable Debt Securities by Type of Security (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 98,325
Gross Unrealized Gains	0
Gross Unrealized Losses	(221)
Fair Value	98,104	$ 0
U.S. Treasury notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	77,550
Gross Unrealized Gains	0
Gross Unrealized Losses	(188)
Fair Value	77,362
U.S. government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	20,775
Gross Unrealized Gains	0
Gross Unrealized Losses	(33)
Fair Value	$ 20,742

Marketable Securities - Summa_2

Marketable Securities - Summary of Fair Value of Available-for-sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less, Amortized Cost	$ 60,462
Maturing in more than one year, Amortized Cost	37,863
Amortized Cost	98,325
Maturing in one year or less, Fair Value	60,406
Maturing in more than one year, Fair Value	37,698
Debt Securities, Available-for-sale, Total	$ 98,104	$ 0

Marketable Securities - Additio

Marketable Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021USD ($)securities	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Investments, Debt and Equity Securities [Abstract]
Available-for-sale marketable debt securities	$ 98,104,000	$ 0
Gain (losses) on marketable securities	0	12,000	$ 7,000
Investments in other-than-temporary decline in fair value	$ 0	0	$ 0
Number of securities, unrealized loss position for less than twelve months | securities	54
Fair value of securities, unrealized loss position for less than twelve months	$ 98,104,000	0
Fair value of securities, unrealized loss position for more than twelve months	$ 0	$ 0

Fair Value of Financial Asset_2

Fair Value of Financial Assets - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	$ 98,104	$ 0
U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	20,742
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	118,413	139,266
Fair Value, Measurements, Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	20,309	139,266
Fair Value, Measurements, Recurring | U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	77,362
Fair Value, Measurements, Recurring | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	20,742
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	20,309	139,266
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	20,309	139,266
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	0
Fair Value, Measurements, Recurring | Level 1 | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	98,104	0
Fair Value, Measurements, Recurring | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	0
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	77,362
Fair Value, Measurements, Recurring | Level 2 | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	20,742
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured on recurring basis	0	0
Fair Value, Measurements, Recurring | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0	$ 0
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	0
Fair Value, Measurements, Recurring | Level 3 | U.S. government agency bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable debt securities	$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 13,404	$ 12,848
Less: Accumulated depreciation and amortization	(7,753)	(6,184)
Property, plant and equipment, net	5,651	6,664
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,653	3,601
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,638	7,638
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	702	535
Furniture and office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,074	1,074
Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 337	$ 0

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 1,569	$ 1,670	$ 1,785

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 2,432	$ 2,797
Unbilled receivable	518	2,571
Interest receivable on marketable securities	247	0
Prepaid expenses and other current assets	$ 3,197	$ 5,368

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued external research and development costs	$ 5,316	$ 4,017
Accrued payroll and payroll-related costs	4,180	5,056
Accrued professional fees	355	327
Other	3,238	1,048
Accrued expenses and other current liabilities	$ 13,089	$ 10,448

Collaboration and License Agr_3

Collaboration and License Agreements - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party		$ 0	$ 38,592,000	$ 15,360,000
Revenue performance obligation		0
License-related revenue		2,687,000	87,570,000	0
Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment for reimbursement of manufacturing costs incurred		0	0
Novartis Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party		0	38,592,000	15,360,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment for reimbursement of manufacturing costs incurred		0	0	0
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment		325,000,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Sales Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment		200,000,000
Novartis Collaboration | Novartis Institutes for Biomedical Research, Inc. | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of share holding	5.00%
GSK Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue performance obligation		$ 0
Expiration period of GSK Agreement (in years)		10 years
Transaction price		$ 90,264,000
GSK Agreement | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License-related revenue		2,687,000	87,570,000	$ 0
GSK Agreement | Transition Services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License-related revenue		733,000	0
GSK Agreement | Supply Services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License-related revenue		1,954,000	2,570,000
GSK Agreement | Transferred at Point in Time | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License-related revenue			$ 85,000,000
GSK Agreement | Transferred over Time | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional payments to be received		4,314,000
GSK Agreement | Transferred over Time | Transition Services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional payments to be received		950,000
GSK Agreement | Clinical Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment		90,000,000
GSK Agreement | Regulatory Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment		155,000,000
GSK Agreement | Sales Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestones payment		$ 485,000,000

Collaboration and License Agr_4

Collaboration and License Agreements - Schedule of Collaboration Revenue Related Party (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party	$ 0	$ 38,592	$ 15,360
License-related revenue	2,687	87,570	0
Novartis Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue - related party	0	38,592	15,360
License | GSK Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License-related revenue	$ 2,687	$ 87,570	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	Aug. 05, 2021USD ($)	May 22, 2020USD ($)	May 01, 2019USD ($)	May 31, 2020USD ($)	Dec. 31, 2021USD ($)vote$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)
Subsidiary, Sale of Stock [Line Items]
Common stock, authorized (shares) | shares					150,000,000	150,000,000
Common stock, par value (in dollars per share) | $ / shares					$ 0.0001	$ 0.0001
Number of votes entitled by each share of common stock holder | vote					1
Dividends, declared or paid					$ 0
Total reserved (shares) | shares					32,934,776	22,728,991
Common stock, issued (shares) | shares					46,958,776	40,707,047
Net proceeds from issuance of common stock					$ 29,525,000	$ 29,086,000	$ 24,000
2021 ATM Facility
Subsidiary, Sale of Stock [Line Items]
Common stock, issued (shares) | shares					1,433,627
Net proceeds from issuance of common stock					$ 10,046,000
2021 ATM Facility | Maximum
Subsidiary, Sale of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 80,000,000				$ 80,000,000
2020 A T M Facility
Subsidiary, Sale of Stock [Line Items]
Common stock, issued (shares) | shares					2,303,545
Net proceeds from issuance of common stock					$ 19,479,000
2020 A T M Facility | Maximum
Subsidiary, Sale of Stock [Line Items]
Gross proceeds from issuance of common stock		$ 50,000,000		$ 50,000,000
2019 ATM Facility
Subsidiary, Sale of Stock [Line Items]
Common stock, issued (shares) | shares					11,229,174
Net proceeds from issuance of common stock					$ 29,110,000
JonesTrading Institutional Services LLC | 2019 ATM Facility | Maximum
Subsidiary, Sale of Stock [Line Items]
Gross proceeds from issuance of common stock			$ 30,000,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Total reserved (shares)	32,934,776	22,728,991
Options to purchase common stock
Class of Stock [Line Items]
Total reserved (shares)	7,057,258	6,011,126
Shares available for future grant
Class of Stock [Line Items]
Total reserved (shares)	783,873	664,544
RSU's issued and expecting to vest
Class of Stock [Line Items]
Total reserved (shares)	0	1,043,300
Shares available for conversion of note payable
Class of Stock [Line Items]
Total reserved (shares)	832,677	1,282,052
Shares available for ATM offering
Class of Stock [Line Items]
Total reserved (shares)	23,176,492	13,003,664
2018 Employee Stock Purchase Plan
Class of Stock [Line Items]
Total reserved (shares)	1,084,476	724,305

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) - USD ($)	Apr. 03, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 8,546,000	$ 7,765,000	$ 5,991,000
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation cost, weighted-average period (in years)		2 years 4 months 9 days
Unrecognized stock-based compensation cost		$ 11,075,000
Stock Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate fair value of stock options vested		10,864,000	6,742,000
Aggregate intrinsic value of stock options exercised		$ 1,887,000	$ 735,000	$ 208,000
Stock Options to purchase common stock | Non-Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock converted under option plan		276,570	253,971
RSUs issued and expected to vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSU's granted (in shares)		0
Unrecognized stock-based compensation cost		$ 0
RSUs issued and expected to vest | Share-based Payment Arrangement, Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 1,103,000
2014 Plan | Stock Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of exercise price per share of stock options to fair market value of share of common stock		100.00%
Stock options granted expiry period (in years)		10 years
Weighted average grant-date fair value per share of stock options granted (in dollars per share)		$ 6.41	$ 2.11
2018 Stock Option and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock to be issued (shares)	1,545,454
Percentage of authorized number of shares of common stock outstanding	4.00%
Number of common stock shares available for further issuance (shares)		783,873	664,544
Number of shares of common stock converted under option plan		7,057,258	6,011,126
2018 Employee Stock Option and Incentive Plan | 2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock to be issued (shares)	256,818	1,084,476
Percentage of authorized number of shares of common stock outstanding	1.00%
Number of shares of common stock issued (shares)		46,899	89,172
2014 Plan and 2018 Plan | Stock Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted expiry period (in years)		10 years
Stock options granted vesting period (in years)		4 years
Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock to be issued (shares)		600,000

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Assumptions used to Determine Fair Value of Stock Options Granted to Employees and Directors (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	0.89%	1.29%	2.46%
Expected term (in years)	5 years 11 months 15 days	5 years 11 months 26 days	6 years 1 month 13 days
Expected volatility	83.87%	71.34%	73.62%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of Stock Option Activity (Details) - 2018 Stock Option and Incentive Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Number of Shares, Outstanding beginning balance (shares)	6,011,126
Number of Shares, Granted (shares)	1,838,905
Number of Shares, Exercised (shares)	(508,720)
Number of Shares, Forfeited (shares)	(284,053)
Number of Shares, Outstanding ending balance (shares)	7,057,258	6,011,126
Number of Shares, Options exercisable at December 31, 2021 (shares)	4,678,355
Number of Shares, Vested and expected to vest at December 31, 2021 (shares)	7,057,258
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding beginning balance (in dollars per share)	$ 5.55
Weighted Average Exercise Price, Granted (in dollars per share)	9.11
Weighted Average Exercise Price, Exercised (in dollars per share)	3.98
Weighted Average Exercise Price, Forfeited (in dollars per share)	5.56
Weighted Average Exercise Price, Outstanding ending balance (in dollars per share)	6.59	$ 5.55
Weighted Average Exercise Price, Options exercisable at December 31, 2021 (in dollars per share)	6.22
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2021 (in dollars per share)	$ 6.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Term (in years), Outstanding	6 years 11 months 23 days	7 years 3 months 10 days
Weighted Average Remaining Contractual Term (in years), Options exercisable	6 years 1 month 17 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest	6 years 11 months 23 days
Aggregate Intrinsic Value	$ 4,678	$ 24,912
Aggregate Intrinsic Value, Options exercisable at December 31, 2021	3,683
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2021	$ 4,678

Stock-Based Awards - RSU Activi

Stock-Based Awards - RSU Activity (Details) - RSUs issued and expected to vest	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Number of Shares
Unvested restricted stock units, beginning balance (in shares) | shares	1,043,300
Unvested restricted stock units, Granted (in shares) | shares	0
Unvested restricted stock units, Vested (in shares) | shares	(997,400)
Unvested restricted stock units, Forfeited (in shares) | shares	(45,900)
Unvested restricted stock units, ending balance (in shares) | shares	0
Weighted Average Grant-Date Fair Value
Weighted Average Grant-Date Fair Value, beginning balance (in dollars per share) | $ / shares	$ 3.21
Weighted Average Grant-Date Fair Value, Granted (in dollars per share) | $ / shares	0
Weighted Average Grant-Date Fair Value, Vested (in dollars per share) | $ / shares	3.21
Weighted Average Grant-Date Fair Value, Forfeited (in dollars per share) | $ / shares	3.18
Weighted Average Grant-Date Fair Value, ending balance (in dollars per share) | $ / shares	$ 0

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Stock-Based Compensation Expense Related to Stock Options, Restricted Stock Awards and ESPP (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 8,546	$ 7,765	$ 5,991
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,431	2,826	2,350
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,115	$ 4,939	$ 3,641

Debt - Additional Information (

Debt - Additional Information (Details) $ / shares in Units, $ in Thousands	Oct. 01, 2021USD ($)$ / shares	Nov. 22, 2019USD ($)segment$ / shares	Aug. 31, 2020USD ($)shares	Feb. 29, 2020USD ($)shares	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2020USD ($)
Debt Instrument [Line Items]
Financing costs					$ 0	$ 0	$ 81
Loan and Security Agreement | K2 Health Ventures LLC
Debt Instrument [Line Items]
Commitment date stock price (in dollars per share) | $ / shares		$ 2.33
Loan and Security Agreement | K2 Health Ventures LLC | Term Loans
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 25,000
Number of potential tranches | segment		3
Final fee percentage		4.45%
Portion of outstanding term loan amount converted			$ 2,000	$ 1,500
Conversion price per share (in dollars per share) | $ / shares		$ 1.56
Beneficial conversion feature		$ 2,101
Number of shares issued upon conversion of term loan (shares) | shares			1,282,050	961,538
Outstanding term loan principal balance				$ 14,000
Interest expense					2,546	$ 2,745	$ 147
Loan and Security Agreement | K2 Health Ventures LLC | Term Loans | Maximum
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted		4,000
Loan and Security Agreement | K2 Health Ventures LLC | First Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		7,500
Loan and Security Agreement | K2 Health Ventures LLC | Second Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		10,000						$ 10,000
Loan and Security Agreement | K2 Health Ventures LLC | Third Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 7,500
Loan Amendment
Debt Instrument [Line Items]
Financing costs					$ 313
Loan Amendment | K2 Health Ventures LLC | Term Loans
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50,000
Final fee percentage	4.25%
Debt instrument interest rate, floating	8.50%
Interest rate, stated percentage	3.25%
Debt instrument variable rate	5.25%
Term of the combined facility (months)	48 months
Aggregate amount needed to extend period	$ 100,000
Prepayment amount	779
Loan Amendment | K2 Health Ventures LLC | Term Loans | First $500,000 Converted at $1.56 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500
Conversion price per share (in dollars per share) | $ / shares	$ 1.56
Loan Amendment | K2 Health Ventures LLC | Term Loans | Additional Amounts Converted in Excess of $500,000 at $7.81 per share
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 500
Conversion price per share (in dollars per share) | $ / shares	$ 7.81
Loan Amendment | K2 Health Ventures LLC | Term Loans | Maximum
Debt Instrument [Line Items]
Portion of outstanding term loan amount converted	$ 4,500
Loan Amendment | K2 Health Ventures LLC | Term Loans | Payment Occurs on or before Twenty Four Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	5.00%
Default interest rate	5.00%
Loan Amendment | K2 Health Ventures LLC | Term Loans | Prepayment Occurs More than Twenty Four Months after, but on or before Thirty Six Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	3.00%
Loan Amendment | K2 Health Ventures LLC | Term Loans | Prepayment Occurs More than Thirty Six Months after Initial Funding Date
Debt Instrument [Line Items]
Prepayment penalty fee percentage	1.00%
Loan Amendment | K2 Health Ventures LLC | First Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000
Loan Amendment | K2 Health Ventures LLC | Second Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	15,000
Loan Amendment | K2 Health Ventures LLC | Third Tranche Term Loan
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10,000

Debt - Schedule of Future Princ

Debt - Schedule of Future Principal Debt Payments on the Loan Payable (Details) $ in Thousands	Dec. 31, 2021USD ($)
Debt Instrument [Line Items]
2025	$ 8,720
Final fee due in 2023	779
Notes Payable
Debt Instrument [Line Items]
2022	0
2023	6,676
2024	9,604
Total principal payments	25,000
Final fee due at maturity in 2025	1,063
Total principal payments and final fee	26,842
Unamortized debt discount and final fee	1,827
Note payable	$ 25,015

Net Income (Loss) per Share - S

Net Income (Loss) per Share - Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income (loss)	$ (78,485)	$ 59,337	$ (54,789)
Denominator:
Weighted average commons shares outstanding—basic (shares)	44,243,317	35,545,121	27,854,912
Net income (loss) per share - basic (in dollars per share)	$ (1.77)	$ 1.67	$ (1.97)
Numerator:
Net income (loss) - basic	$ (78,485)	$ 59,337	$ (54,789)
Interest expense on convertible note payable	0	395	0
Net income (loss) - diluted	$ (78,485)	$ 59,732	$ (54,789)
Denominator:
Weighted average commons shares outstanding—basic (shares)	44,243,317	35,545,121	27,854,912
Shares issuable upon conversion of convertible notes, as if converted (shares)	0	1,282,052	0
Dilutive effect of restricted stock units (shares)	0	557,402	0
Dilutive effect of common stock equivalents (shares)	0	757,218	0
Weighted average common shares outstanding—diluted (shares)	44,243,317	38,141,793	27,854,912
Net income (loss) per share - diluted (in dollars per share)	$ (1.77)	$ 1.57	$ (1.97)

Net Income (Loss) per Share -_2

Net Income (Loss) per Share - Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Stock Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share (shares)	7,057,258	3,146,458
Shares to be issued under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share (shares)	1,084,476	0
RSUs issued and expected to vest
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share (shares)	0	2,400
Shares available from conversion of note payable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share (shares)	832,677	0

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Mar. 31, 2021	Nov. 30, 2020	Jul. 31, 2014	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
License Agreements
Research and development				$ 53,572	$ 41,018	$ 52,118
Adimab LLC
License Agreements
Option fee percentage			65.00%
Adimab LLC | License Agreements
License Agreements
Research and development				3,000	3,092	$ 1,175
Adimab LLC | Maximum
License Agreements
Technical milestones payment			$ 250
License agreement milestone payments			$ 13,000
MSK | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
License Agreements
License agreement milestone payments		$ 7,500
Research and development				$ 50	$ 50
Upfront license execution fee due		$ 100
Timing of satisfaction				10 years
Vaccinex, Inc. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
License Agreements
Payments to related party				$ 850,000
Vaccinex, Inc. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Clinical Milestone Payment
License Agreements
License agreement milestone payments	$ 3,500
Vaccinex, Inc. | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Regulatory Milestone Payment
License Agreements
License agreement milestone payments	$ 11,500

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Before Taxes:
Domestic	$ (78,485)	$ 59,346	$ (54,789)
Foreign	0	0	0
Total income (loss) before income taxes	$ (78,485)	$ 59,346	$ (54,789)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 0	$ 0	$ 0
Period of measurement for change in ownership (in years)	3 years
Unrecognized tax benefits	$ 0	0
Interest and penalties accrued	$ 0	0
Minimum
Operating Loss Carryforwards [Line Items]
Percentage increase in the ownership	50.00%
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 92,735,000	31,394,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	155,989,000	32,312,000
Research and Development | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	9,747,000	6,259,000
Research and Development | State
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 3,067,000	$ 2,545,000

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)	(21.00%)
State taxes, net of federal benefit	(12.50%)	(6.30%)	(6.20%)
Stock-based compensation	0.20%	(0.50%)	1.00%
Research and development tax credits	(5.00%)	3.20%	(7.90%)
Change in deferred tax asset valuation allowance	38.10%	24.50%	33.70%
Other	0.20%	0.10%	0.40%
Effective income tax rate	0.00%	0.00%	0.00%

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 30,313	$ 8,635
Research and development tax credit carryforwards	12,230	8,344
Intangible assets	1,812	1,235
Accrued expenses	1,422	0
Stock-based compensation	5,237	3,911
Lease liability	8,808	9,428
Interest expense	269	0
Other	180	0
Total deferred tax assets	60,271	31,553
Valuation allowance	(51,957)	(21,961)	$ (36,535)	$ (18,602)
Deferred tax assets	8,314	9,592
Deferred tax liabilities:
Right-of-use asset	(7,056)	(7,625)
Depreciation	(1,150)	(1,478)
Beneficial conversion feature on convertible note payable	(32)	(397)
Other	(76)	(92)
Total deferred tax liabilities	(8,314)	(9,592)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Changes in the V

Income Taxes - Changes in the Valuation Allowance for Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance at beginning of year	$ (21,961)	$ (36,535)	$ (18,602)
Increases recorded to income tax provision	(30,616)	(11,675)	(17,933)
Decreases recorded as a benefit to income tax provision	620	26,249	0
Valuation allowance at end of year	$ (51,957)	$ (21,961)	$ (36,535)

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2020USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jan. 01, 2019USD ($)	May 30, 2018ft²	May 31, 2016
Lease Agreements [Line Items]
Cash paid for lease liabilities		$ 7,916	$ 6,608
Sublease income		$ (3,371)	$ (3,169)
Massachusetts
Lease Agreements [Line Items]
Lease term (in years)					10 years	10 years
Renewal terms of lease (in years)		5 years
Operating lease, incentives				$ 4,803
Massachusetts | Lease Amendment | Sublease agreement with EQRx
Lease Agreements [Line Items]
Land subject to additional ground leases (sq ft) | ft²					33,526
Massachusetts | Accounting Standards Codification Topic 605 | Office Space
Lease Agreements [Line Items]
Payments for Tenant Improvements	$ 1,005
Lease incentive as a reduction of rental payments	$ 1,005
Massachusetts | Minimum
Lease Agreements [Line Items]
Lease term (in years)		1 year
Operating lease, discount rate		9.50%
Massachusetts | Maximum
Lease Agreements [Line Items]
Lease term (in years)		8 years
Operating lease, discount rate		10.50%

Leases - Summary of Components

Leases - Summary of Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lease Agreements [Line Items]
Operating lease cost	$ 2,041	$ 1,950	$ 1,814
Total lease cost	$ 7,106	$ 7,157	$ 4,194
Weighted-average discount rate	10.50%	10.50%	10.50%
Weighted-average remaining lease term (in months)	8 years 2 months 22 days	9 years 1 month 26 days	9 years 11 months 18 days
Research and development expenses
Lease Agreements [Line Items]
Operating lease cost	$ 2,000	$ 2,111	$ 2,312
Variable lease costs	641	585	707
General and administrative expenses
Lease Agreements [Line Items]
Operating lease cost	3,353	3,292	899
Variable lease costs	$ 1,112	$ 1,169	$ 276

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2022	$ 5,385	$ 5,529
2023	5,413	5,385
2024	5,533	5,413
2025	5,656	5,533
2026	5,782	5,656
Thereafter	20,083	25,865
Total future lease payments	47,852	$ 53,381
Less: Interest	(15,559)
Present value of future lease payments (lease liability)	$ 32,293

Leases - Sublease (Details)

Leases - Sublease (Details) - Sublease agreement with EQRx $ in Thousands	Dec. 31, 2021USD ($)
Lessor, Lease, Description [Line Items]
2022	$ 2,884
2023	241
Total Sublease Receivable	$ 3,125

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Preferred stock shares issued to related party (shares)		0	0
Novartis Institutes for Biomedical Research, Inc.
Related Party Transaction [Line Items]
Payment for reimbursement of manufacturing costs incurred		$ 0	$ 0
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration
Related Party Transaction [Line Items]
Amounts due from related party		0	0
Payment for reimbursement of manufacturing costs incurred		$ 0	0	$ 0
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Minimum
Related Party Transaction [Line Items]
Percentage of share holding	5.00%
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Series A One Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Preferred stock shares issued to related party (shares)	2,000,000
Gross proceeds from issuance of preference stock	$ 13,500,000
Novartis Institutes for Biomedical Research, Inc. | Novartis Collaboration | Private Placement
Related Party Transaction [Line Items]
Issuance of common stock (shares)		766,666
Share price (in dollars per share)	$ 15
Proceeds from collaboration arrangement	$ 11,500,000
Vaccinex, Inc.
Related Party Transaction [Line Items]
Due to related party		$ 0	0
Vaccinex, Inc. | Vaccinex License Agreement | Research and development expenses
Related Party Transaction [Line Items]
Payments to related party		850,000
Vaccinex, Inc. | Vaccinex Research Agreement | Research and development expenses
Related Party Transaction [Line Items]
Payments to related party		$ 50,000	$ 50,000	$ 606,000

401(K) Savings Plan - Additiona

401(K) Savings Plan - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Contributions made under the savings plan	$ 403	$ 370	$ 399
Employer Match One
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of match	100.00%
Employer matching contribution, percent of employees' gross pay	3.00%
Employer Match Two
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of match	50.00%
Minimum | Employer Match Two
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay	3.00%
Maximum | Employer Match Two
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay	5.00%