Relay Therapeutics (RLAY) 10-K 24 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 18, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	RELAY THERAPEUTICS, INC.
Entity Central Index Key	0001812364
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 2,264
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		108,280,044
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	RLAY
Security Exchange Name	NASDAQ
Entity File Number	001-39385
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-3923475
Entity Address, Address Line One	399 Binney Street
Entity Address, Address Line Two	2nd 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	370-8837
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE The Registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2022 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2021 . Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.
Auditor Firm ID	42
Auditor Name	Ernst & Young
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 280,119,000	$ 447,646,000
Investments	677,954,000	230,415,000
Accounts receivable	403,000	75,000,000
Contract asset	4,537,000	7,654,000
Prepaid expenses and other current assets	13,229,000	9,385,000
Total current assets	976,242,000	770,100,000
Property and equipment, net	6,543,000	6,250,000
Operating lease assets	20,780,000	22,579,000
Restricted cash	2,578,000	878,000
Intangible asset	2,300,000
Other assets		22,000
Total assets	1,008,443,000	799,829,000
Current liabilities:
Accounts payable	8,276,000	6,351,000
Accrued expenses and other current liabilities	13,953,000	5,760,000
Operating lease liabilities, current	1,844,000	1,521,000
Deferred revenue	248,000
Total current liabilities	24,321,000	13,632,000
Operating lease liabilities, net of current portion	21,056,000	22,901,000
Restricted stock liability		3,000
Contingent consideration liability	50,258,000	0
Other liabilities	15,000,000
Total liabilities	110,635,000	36,536,000
Commitments and contingencies (Note 13)
Stockholders' equity
Undesignated preferred stock, $0.001 par value, 10,000,000 shares authorized as of December 31, 2021 and December 31, 2020; no shares issued and outstanding at December 31, 2021 and December 31, 2020	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized at December 31, 2021 and December 31, 2020, respectively; 108,210,318 and 89,991,324 shares issued at December 31, 2021 and December 31, 2020, respectively; 108,210,318 and 89,906,835 shares outstanding at December 31, 2021 and December 31, 2020, respectively	109,000	90,000
Additional paid-in capital	1,666,887,000	1,167,367,000
Accumulated other comprehensive (loss) income	(1,088,000)	64,000
Accumulated deficit	(768,100,000)	(404,228,000)
Total stockholders' equity	897,808,000	763,293,000
Total liabilities and stockholders' equity	$ 1,008,443,000	$ 799,829,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Common stock par value	$ 0.001	$ 0.001
Common stock shares authorized	150,000,000	150,000,000
Common stock shares issued	108,210,318	89,991,324
Common stock shares outstanding	108,210,318	89,906,835
Undesignated Preferred Stock [Member]
Preferred stock par value	$ 0.001	$ 0.001
Preferred stock shares authorized	10,000,000	10,000,000
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue:
Revenue from contract with customer	$ 3,029	$ 82,654
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Total revenue	$ 30,290	$ 82,654
Operating expenses:
Research and development expenses	172,650	99,862	$ 70,306
In-process research and development expenses	123,000
Loss on initial consolidation of variable interest entity	11,855
Change in fair value of contingent consideration liability	2,836
General and administrative expenses	57,386	38,588	13,742
Total operating expenses	367,727	138,450	84,048
Loss from operations	(364,698)	(55,796)	(84,048)
Other income (expense):
Interest income	830	3,400	8,801
Other expense	(4)	(16)	(58)
Total other income, net	826	3,384	8,743
Net loss	(363,872)	(52,412)	(75,305)
Deemed dividend resulting from extinguishment upon modification of Series C preferred stock		(177,789)
Net loss attributable to common stockholders	$ (363,872)	$ (230,201)	$ (75,305)
Net loss attributable to common stockholders per share, basic and diluted	$ (3.82)	$ (5.40)	$ (21.82)
Weighted average shares of common stock, basic and diluted	95,136,719	42,619,582	3,450,500
Other comprehensive income (loss):
Unrealized holding (loss) gain	$ (1,152)	$ (261)	$ 325
Total other comprehensive (loss) income	(1,152)	(261)	325
Total comprehensive loss	$ (365,024)	$ (52,673)	$ (74,980)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Preferred Stock [Member]Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2018	$ (110,927)	$ 532,120	$ 3	$ 3,247		$ (114,177)
Beginning balance, shares at Dec. 31, 2018		210,863,764	2,998,017
Issuance of Series C convertible preferred stock, net of issuance costs of $50		$ 5,661
Issuance of Series C convertible preferred stock, net of issuance costs of $50, shares		1,779,093
Issuance of common stock upon exercise of stock options	613			613
Issuance of common stock upon exercise of stock options, shares			178,969
Vesting of restricted common stock	400		$ 1	399
Vesting of restricted common stock ,shares			860,490
Stock-based compensation expense	4,456			4,456
Unrealized gain (loss) on investments	325				$ 325
Net loss	(75,305)					(75,305)
Ending balance at Dec. 31, 2019	(180,438)	$ 537,781	$ 4	8,715	325	(189,482)
Ending balance, shares at Dec. 31, 2019		212,642,857	4,037,476
Extinguishment upon modification of Series C preferred stock	(177,789)	$ 177,789		(15,455)		(162,334)
Conversion of convertible preferred stock into common stock upon initial public offering	715,570	$ (715,570)	$ 62	715,508
Conversion of convertible preferred stock into common stock upon initial public offering, shares		(212,642,857)	61,992,534
Issuance of common stock in follow-on offering, net of discounts and issuance costs	425,293		$ 23	425,270
Issuance of common stock in follow-on offering, net of discounts and issuance costs, shares			23,000,000
Issuance of common stock upon exercise of stock options	1,216			1,216
Issuance of common stock upon exercise of stock options, shares			297,000
Vesting of restricted common stock	154		$ 1	153
Vesting of restricted common stock ,shares			579,825
Stock-based compensation expense	31,960			31,960
Unrealized gain (loss) on investments	(261)				(261)
Net loss	(52,412)					(52,412)
Ending balance at Dec. 31, 2020	763,293		$ 90	1,167,367	64	(404,228)
Ending balance, shares at Dec. 31, 2020			89,906,835
Purchase of common stock under ESPP	1,141		$ 1	1,140
Purchase of common stock under ESPP, shares			43,685
Issuance of common stock in follow-on offering, net of discounts and issuance costs	382,210		$ 15	382,195
Issuance of common stock in follow-on offering, net of discounts and issuance costs, shares			15,188,679
Issuance of common stock upon exercise of stock options	4,739		$ 1	4,738
Issuance of common stock upon exercise of stock options, shares			996,536
Vesting of restricted common stock	3			3
Vesting of restricted common stock ,shares			160,364
Stock-based compensation expense	48,454			48,454
Shares issued in connection with acquisition of ZebiAI	62,992		$ 2	62,990
Shares issued in connection with acquisition, shares			1,914,219
Unrealized gain (loss) on investments	(1,152)				(1,152)
Net loss	(363,872)					(363,872)
Ending balance at Dec. 31, 2021	$ 897,808		$ 109	$ 1,666,887	$ (1,088)	$ (768,100)
Ending balance, shares at Dec. 31, 2021			108,210,318

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net of discounts and issuance costs	$ 20,290	$ 34,707
Convertible Preferred Stock [Member]
Issuance costs net			$ 50

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 loss	$ (363,872)	$ (52,412)	$ (75,305)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	48,454	31,960	4,456
Depreciation expense	3,925	3,549	2,845
Net amortization of premiums and discounts on investments	2,052	(416)	(2,495)
Acquired in-process research and development	123,000
Loss on initial consolidation of variable interest entity	11,855
Change in fair value of contingent consideration liability	2,836
Loss on sale of equipment			56
Changes in assets and liabilities:
Prepaid expenses and other current assets	(2,681)	(4,665)	(2,123)
Operating lease assets and liabilities, net	277	571	1,233
Accounts payable	930	(410)	3,000
Accrued expenses and other liabilities	6,002	2,010	2,200
Accounts receivable	74,677	(75,000)
Contract asset	3,117	(7,654)
Other liabilities	15,000
Other assets	22	(22)
Net cash used in operating activities	(74,406)	(102,489)	(66,133)
Cash flows from investing activities:
Purchases of property and equipment	(3,471)	(1,931)	(8,002)
Proceeds from sale of equipment			20
Purchases of investments	(980,665)	(266,455)	(553,517)
Proceeds from maturities of investments	529,923	350,058	242,475
Cash paid for acquisition of ZebiAI, net of cash acquired	(25,298)
Net cash provided by (used in) investing activities	(479,511)	81,672	(319,024)
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs			4,993
Proceeds from issuance of common stock upon exercise of stock options	4,739	1,216	613
Proceeds from issuance of common stock upon initial public offering, net		425,293
Proceeds from issuance of common stock upon follow-on offering, net	382,210
Proceeds from issuance of common stock under ESPP	1,141
Net cash provided by financing activities	388,090	426,509	5,606
Net (decrease) increase in cash, cash equivalents and restricted cash	(165,827)	405,692	(379,551)
Cash, cash equivalents and restricted cash at beginning of period	448,524	42,832	422,383
Cash, cash equivalents and restricted cash at end of period	282,697	448,524	42,832
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment additions included in accounts payable and accrued expenses	1,010	519	745
Reclassification of restricted stock liability to additional paid-in capital	3	153	400
Assets obtained in asset acquisition	662
Liabilities assumed in asset acquisition	2,330
Fair value of equity issued in connection with asset acquisition	$ 62,990
Extinguishment upon modification of Series C preferred stock		(177,789)
Conversion of preferred stock into common stock upon initial public offering		715,508
Right of use asset obtained in exchange for lease obligation		$ 819	$ 24,936

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restricted Cash And Cash Equivalents At Carrying Value [Abstract]
Cash and cash equivalents	$ 280,119	$ 447,646	$ 41,954
Restricted cash	2,578	878	878
Total cash, cash equivalents and restricted cash as shown on consolidated statements of cash flows	$ 282,697	$ 448,524	$ 42,832

Nature of Business and Basis of

Nature of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2021
Text Block [Abstract]
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Relay Therapeutics, Inc. (the “Company”) was incorporated in Delaware on May 4, 2015 and is headquartered in Cambridge, Massachusetts. The Company is a clinical-stage, precision medicines company transforming the drug discovery process by combining leading-edge computational and experimental technologies with the goal of bringing life-changing therapies to patients. The Company is among the first of a new breed of biotech created at the intersection of disparate disciplines. The Company’s Dynamo™ platform integrates an array of leading-edge computational and experimental approaches designed to drug protein targets that have previously been intractable or inadequately addressed. The Company’s initial focus is on enhancing small molecule therapeutic discovery in targeted oncology and genetic disease indications. The Company’s lead product candidates, RLY-4008, RLY-2608 and RLY-1971, are in clinical development. The Company also has over five discovery stage programs across both precision oncology and genetic disease indications. The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical 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. The Company’s product candidates are in development. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants. The Company has devoted substantially all of its resources to developing its product candidates, including RLY-4008, RLY-2608 and RLY-1971, by developing its computation and experimental approaches, building its intellectual property portfolio, business planning, raising capital and providing general and administrative support for these operations. The Company has incurred net operating losses since inception and had an accumulated deficit of $ 768.1 million as of December 31, 2021. The Company expects that its existing cash, cash equivalents and investments as of December 31, 2021 will enable it to fund its planned operating expenses and capital expenditure requirements for at least one year from the date of the issuance of these consolidated financial statements. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a material adverse effect on its financial condition and ability to pursue its business strategies. 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 license or collaboration arrangements or obtain government grants. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects. In the event the Company requires additional funding, there can be no assurance that it will be successful in obtaining sufficient funding on terms acceptable to the Company to fund its continuing operations, if at all.

Significant Accounting Policie

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	2. 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 pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for reporting on Form 10-K. The Company’s consolidated financial statements include the accounts of Relay Therapeutics, Inc. and its wholly-owned subsidiaries, Relay Therapeutics Securities Corporation and Relay ML Discovery, LLC. All intercompany balances and transactions have been eliminated. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual of research and development and manufacturing expenses, the valuation of equity instruments, the determination of the transaction price and standalone selling price of performance obligations under Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606, Revenue from Contracts with Customers ("ASC 606"), the incremental borrowing rate for determining the operating lease assets and liabilities and the fair value of contingent consideration and the fair value of net assets acquired in the acquisition of ZebiAI Therapeutics, Inc. (“ZebiAI”). Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on using innovative experimental and computational approaches on protein motion for making medicines to drug protein targets that have previously been intractable or inadequately addressed. The Company operates in the United States and all tangible assets are held in the United States. Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market funds, are stated at fair value. Restricted Cash The Company had restricted cash of $ 2.6 million and $ 0.9 million as of December 31, 2021 and 2020 , respectively, to secure letters of credit in connection with the leases of the Company’s facilities (see Note 14). The Company classified the restricted cash as a noncurrent asset on its consolidated balance sheets, consistent with the terms of the underlying lease agreements. Investments Investments in marketable securities are classified as available-for-sale. Available-for-sale 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 securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. All of the Company’s available-for-sale securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the consolidated statements of operations and comprehensive loss. If any adjustment is required to reflect a decline in the value of the investment that the Company considers to be “other than temporary”, the Company recognizes a charge to the consolidated statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented. Concentration of Credit Risk and Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and investments. From time to time, the Company has maintained all of its cash, cash equivalents and investments at certain accredited financial institutions in amounts that exceed federally insured limits. The Company generally invests its excess capital in money market funds, U.S. treasury bonds, U.S. treasury bills and agency bonds, all of which are subject to minimal credit and market risk. Management has established guidelines relative to credit ratings and maturities intended to safeguard principal balances and maintain liquidity. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. The Company is dependent on third-party suppliers for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relies and expects to continue to rely on a small number of these suppliers, including D. E. Shaw Research, LLC as discussed in Note 13, to meet its requirements for its programs. These programs could be adversely affected by a significant interruption in pre-clinical and clinical testing and the supply of active pharmaceutical ingredients and formulated drugs. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Revenue Recognition The Company accounts for revenue recognition in accordance with ASC 606, Revenue from Contracts with Customers . Under ASC 606, an entity 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 an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with customer(s); (ii) identify the performance obligation(s) in the contract(s); (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract(s); and (v) recognize revenue when (or as) the entity satisfies a performance obligation. 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 and determines those that are performance obligations. The Company then determines the transaction price and allocates it to the performance obligations. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the number of performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above, including the determination of whether milestones or other variable consideration should be included in the transaction price; and (c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of the transaction price in step (iv) above. The Company utilizes key assumptions and judgments to determine the stand-alone selling price for each performance obligation, which may include discounted cash flow models, evaluation of comparable transactions, pricing considered in negotiating the transaction and estimated costs, to determine how the transaction price is allocated among the performance obligations . The Company uses judgment to determine whether milestones or other variable consideration should be included in the transaction price. As part of management’s evaluation of the transaction price, the Company considers numerous factors, including whether the achievement of the milestones is outside of our control, contingent upon the efforts of others or subject to scientific risks of success. If the Company concludes it is probable that a significant revenue reversal would not occur, the associated milestone payment is included in the transaction price. Milestone payments that are not within our control, such as regulatory approvals, are generally not considered probable until those milestones are achieved. The Company re-evaluates the transaction price, including estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. For revenue-based royalties, including milestone payments based on the level of sales, the Company will include royalties in the transaction price at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty is allocated has been satisfied (or partially satisfied). Once the performance obligations are identified, the transaction price is allocated to each performance obligation based on the relative stand-alone selling price. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied, either at a point in time or over time. If the performance obligation is satisfied over time, the Company recognizes revenue based on the use of either an output or input method. Collaboration Agreements The Company enters into collaborative agreements with third parties to research, develop and commercialize drug candidates, pursuant to which the risks and rewards for such activities are shared between the parties. Such arrangements also provide for cost sharing between the parties during the research and development phase, as well as potential future profit share payments during the commercialization phase. In general, such contracts are evaluated under the provisions of FASB ASC 808, Collaborative Arrangements (“ASC 808”). The amounts receivable and payable for research and development activities are presented net within research and development expense on the consolidated statement of operations, as such the net costs reflect the Company’s share of the ongoing research and development efforts. The amounts receivable and payable for commercialization activities are presented net as either collaboration revenue, separate from revenue from contracts with customers, or collaboration expense on the consolidated statement of operations, as appropriate. Lease Agreements Under ASC 842, Leases , the Company determines if an arrangement is or contains a lease at inception. For leases with a term of 12 months or less, the Company does not recognize a right-of-use asset or lease liability. The Company’s operating leases are recognized on its consolidated balance sheets as other noncurrent assets, other current liabilities and other noncurrent liabilities. The Company does not have any finance leases. Right-of-use 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 right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an estimate of its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. Operating lease right-of-use assets also include the effect of any lease payments made prior to commencement and excludes lease incentives. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for as a combined element. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the useful life of the asset. Laboratory and computer equipment are depreciated over three years . Furniture and fixtures are depreciated over five years . Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations. Impairment of Long-Lived Assets The Company continually evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book values of the assets to the expected future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured in an amount by which the book values of the assets exceed their fair value. The Company did no t recognize any impairment losses for the years ended December 31, 2021, 2020 and 2019. Stock-Based Compensation The Company measures stock options and other stock-based awards granted to employees, directors and non-employees based on their fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. The Company recognizes the impact of forfeitures on stock-based compensation expense as forfeitures occur. The Company estimates the fair value of each stock option grant on the date of grant using the Black-Scholes option-pricing model, which uses as inputs the fair value of the Company’s common stock and assumptions the Company makes for the volatility of its common stock, the expected term of the stock options, the risk-free interest rate for a period that approximates the expected term of the stock options and the expected dividend yield. Prior to the Company’s IPO, the estimated fair value of its common stock was determined by the board of directors, or compensation committee thereof, as of the date of each option grant, with input from management, considering the most recently available third-party valuations of common stock and the board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of the grant. Historically, these independent third-party valuations of the Company’s equity instruments were performed contemporaneously with identified value inflection points. These third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “Practice Aid”). The Practice Aid identifies various available methods for allocating the enterprise value across classes of series of capital stock in determining the fair value of the Company’s common stock at each valuation date. Following the Company’s IPO, in connection with the accounting for granted stock options and other awards the Company may grant, the fair value of the Company’s common stock is determined based on the quoted market price of its common stock. 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 pre-clinical studies and clinical trials. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. Research and Manufacturing Contracts The Company has entered into various research and development contracts with research institutions and other companies whose costs are included in research and development expense in the accompanying consolidated statements of operations and comprehensive loss. These agreements are generally cancelable and related payments are recorded as research and development expenses as the underlying services are performed. When evaluating the adequacy of the expense recognized, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Judgments and estimates are made in determining the expense recognized and the related prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical estimates have not been materially different from the actual costs. Acquired In-Process Research and Development In an asset acquisition, the cost allocated to acquire in-process research and development (“IPR&D”) with no alternative future use is charged to expense at the acquisition date. Refer to Note 5, Acquisition of ZebiAI, for a more detailed description of the accounting policies applied to the asset acquisition. 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. Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. 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 the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2021, 2020 and 2019, other comprehensive income (loss) consisted of changes in unrealized gains and losses from available-for-sale investments. Net Loss Per Common Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and the effect of dilutive securities. The Company applies the two-class method to calculate its basic and diluted net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. The Company’s participating securities contractually entitle the holders of such shares to participate in dividends; but do not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. Additionally, in periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. For additional discussion of net loss per common share, please see Note 12, Net Loss Per Share. Recently Adopted Accounting Pronouncements The Company adopted Accounting Standards Update (“ASU”) No. 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). This standard amends the guidance on convertible instruments and the derivatives scope exception for contracts in an entity’s own equity and amends the related earnings per share (“EPS”) guidance. The Company adopted this standard on January 1, 2021 and the adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures. The Company adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends certain aspects of the existing guidance to improve consistent application. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures. Recently Issued Accounting Pronouncements Not Yet Adopted 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”). This standard requires that credit losses be reported as an allowance using an expected losses model, representing the entity’s current estimate of credit losses expected to be incurred. The accounting guidance in effect for the Company through December 31, 2021 is based on an incurred losses model. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The Company adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures .

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	3. Fair Value of Financial Assets The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 251,891 $ — $ — $ 251,891 Investments: US treasury bills — 469,386 — 469,386 US agency securities — 208,568 — 208,568 Total investments — 677,954 — 677,954 Total assets $ 251,891 $ 677,954 $ — $ 929,845 Liabilities Contingent Milestone Payments $ — $ — $ 45,258 $ 45,258 Total liabilities $ — $ — $ 45,258 $ 45,258 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 447,146 $ — $ — $ 447,146 Investments: US treasury bills — 33,026 — 33,026 US agency securities — 197,389 — 197,389 Total investments — 230,415 — 230,415 Total $ 447,146 $ 230,415 $ — $ 677,561 In determining the fair value of its investments at each date presented above, the Company relied on quoted prices for similar securities in active markets or using other inputs that are observable or can be corroborated by observable market data. Fair Value of Contingent Consideration In April 2021, the Company acquired ZebiAI, as discussed further in Note 5. The Company’s Level 3 contingent consideration liability is related to $ 85.0 million of platform and program-related milestones (“Contingent Milestone Payments”) potentially payable to ZebiAI’s former equity holders. The contingent consideration liability for the Contingent Milestone Payments is measured at fair value at each reporting date pursuant to FASB ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”), as discussed further in Note 5. The Company determines the fair value of the Contingent Milestone Payments based on the probability of achieving the milestones, the related timing, and, to a lesser extent, an appropriate discount rate. Significant judgment is used in determining the appropriateness of these assumptions. Due to the uncertainties associated with the development of platforms and drug candidates in the pharmaceutical industry and the effects of changes in assumptions including probability of success and related timing, the Company expects its estimates regarding the fair value of Contingent Milestone Payments to continue to change in the future, resulting in adjustments to the fair value of the Company’s Contingent Milestone Payments, and the effect of any such adjustments could be material. The Company also has a contingent consideration liability related to the fair value of the $ 100.0 million earnout payments (“Contingent Earnout Payments”), which was a nonrecurring fair value measurement as of the acquisition date, as further discussed in Note 5. The following table reconciles the change in fair value of the contingent consideration liability (in thousands): Year Ended December 31, 2021 Balance at December 31, 2020 $ — Contingent Milestone Payments related to acquisition of ZebiAI 42,422 Contingent Earnout Payments related to acquisition of ZebiAI 5,000 Increase in fair value of Contingent Milestone Payments 2,836 Balance at December 31, 2021 $ 50,258 The “Increase in fair value of Contingent Milestone Payments” in the table above was primarily attributable to the time value of money.

Investments

Investments	12 Months Ended
	Dec. 31, 2021
Schedule Of Investments [Abstract]
Investments	4. Investments The fair value of available-for-sale investments by type of security was as follows: December 31, 2021 Amortized Unrealized Unrealized Fair Investments: U.S treasury bills $ 189,406 $ ( 228 ) $ 189,178 U.S agency securities 108,895 ( 138 ) 108,757 Total investments with a maturity of one year or less 298,301 — ( 366 ) 297,935 U.S treasury bills 280,743 ( 535 ) 280,208 U.S agency securities 99,998 ( 187 ) 99,811 Total investments with a maturity of one to two years 380,741 — ( 722 ) 380,019 Total investments $ 679,042 $ — $ ( 1,088 ) $ 677,954 December 31, 2020 Amortized Unrealized Unrealized Fair Investments: U.S treasury bills $ 29,997 $ 21 $ — $ 30,018 U.S agency securities 20,996 5 — 21,001 Total investments with a maturity of one year or less 50,993 26 — 51,019 U.S treasury bills 3,008 — — 3,008 U.S agency securities 176,350 38 — 176,388 Total investments with a maturity of one to two years 179,358 38 — 179,396 Total investments $ 230,351 $ 64 $ — $ 230,415 The Company held 88 and 9 debt securities that were in an unrealized loss position as of December 31, 2021 and 2020, respectively. The aggregate fair value of debt securities in an unrealized loss position was $ 667.0 million and $ 70.5 million as of December 31, 2021 and 2020, respectively. As of December 31, 2021 and 2020, the Company did no t hold any debt securities in a continuous unrealized loss position for more than 12 months. The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if we have the intent to sell the investment or if it is more likely than not that the Company will be required to sell the investment before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with our investment policy, the severity and the duration of the impairment, and changes in value subsequent to the end of the period. The unrealized losses at December 31, 2021 and 2020 are attributable to changes in interest rates, and we do no t believe any unrealized losses represent other-than-temporary impairments.

Acquisition of ZebiAI

Acquisition of ZebiAI	1 Months Ended
	Jan. 31, 2021
Business Combination, Description [Abstract]
Acquisition of ZebiAI	5. Acquisition of ZebiAI On April 22, 2021 (the “Acquisition Date”), the Company acquired ZebiAI, a privately held company focused on using machine learning combined with DNA encoded library data sets for drug discovery. Pursuant to the Agreement and Plan of Merger (the “Merger Agreement”), the Company was required to pay ZebiAI’s former stockholders, option holders and warrant holders (“the ZebiAI Holders”) upfront consideration of approximately $ 20.0 million in cash and issue 1,914,219 shares of the Company’s common stock at an aggregate fair value of $ 61.8 million. In addition, (i) the ZebiAI Holders will be eligible to receive up to an additional $ 85.0 million in milestone payments upon the achievement of certain platform or program-related milestones, payable in common stock (the “Contingent Milestone Payments”), and (ii) the Company will pay to the ZebiAI Holders 10 % of the payments it receives within three years of the closing date of the Merger Agreement from partnering, collaboration or other agreements related to ZebiAI’s platform up to an aggregate maximum amount of $ 100.0 million, payable in cash (the “Contingent Earnout Payments”). The Company assessed if ZebiAI represented an asset or a business under FASB ASC Topic 805, Business Combinations (“ASC 805”), as amended by ASU 2017-01. Under ASC 805, the Company determined that ZebiAI did not constitute a business, since substantially all of the fair value of the gross assets acquired is concentrated in a single asset, which is the intellectual property for the AI platform and the related data sets in development by ZebiAI. The intellectual property acquired from ZebiAI is at an early stage of development and will require a significant investment of time and capital for development. There is no assurance that the Company will be successful in completing the additional research and development activities. The Company also determined that the acquisition represented an initial consolidation of a variable interest entity that does not constitute a business in accordance with FASB Topic 810, Consolidation (“ASC 810”), primarily as a result of the fact that ZebiAI was deemed to be a variable interest entity, as it did not have sufficient equity to finance its activities without additional subordinated financial support. Prior to the Acquisition Date, the source of funding for ZebiAl had primarily been preferred stock financings and convertible notes. The Company acquired all of the outstanding shares of ZebiAI and, therefore, is the sole equity holder. The Company will absorb the losses of ZebiAI, has the rights to the benefits derived from the ZebiAI platform, and the power to direct all activities and, therefore, is the primary beneficiary. As a result, the net assets acquired and liabilities assumed in connection with the ZebiAI acquisition were recorded at their estimated fair values as of the Acquisition Date. Total consideration transferred of $ 135.5 million included the cash and shares issued to ZebiAI Holders, the fair value of the Contingent Milestone Payments and the Contingent Earnout Payments and an insignificant amount attributed to the replacement of stock options to ZebiAI Holders. The Contingent Milestone Payments were determined to be liabilities pursuant to ASC 480 and, therefore, were included in consideration transferred. The Contingent Earnout Payments were required to be included in total consideration transferred as a result of the guidance under ASC 810. The difference between total consideration transferred and the fair value of net assets acquired and liabilities assumed of $ 11.9 million was recorded as loss on initial consolidation of a variable interest entity pursuant to ASC 810. The following table summarizes the net assets acquired based on their estimated fair values as of the Acquisition Date (in thousands): Acquired IPR&D asset $ 123,000 Loss on initial consolidation of VIE 11,855 Assets obtained in asset acquisition 662 Liabilities assumed in asset acquisition ( 2,330 ) Intangible asset 2,300 Net acquired assets $ 135,487 In estimating the fair value of the acquired tangible assets and liabilities assumed, the Company used the carrying value of the net working capital balances as the most reliable indicator of fair value based on the associated short-term nature of the balances. The remaining fair value was attributable to the acquired IPR&D and an intangible asset. The fair value attributable to the IPR&D asset was determined using an Avoided Cost Method that includes all costs to develop the IPR&D asset, including appropriate mark-ups on the cost estimate and an expected return related to developing the IPR&D asset over a period of time. The fair value of the IPR&D asset was expensed in the Company’s consolidated statements of operations and comprehensive loss for the year ended December 31, 2021, as the acquired IPR&D had no alternative future use, as determined by the Company in accordance with U.S. GAAP, including ASC 730. The intangible asset represents the assembled workforce, for which the Company concluded there were no indicators of impairment through December 31, 2021. The Company recognized stock-based compensation expense associated with the accelerated vesting for certain stock options in connection with the acquisition of ZebiAI in the amount of $ 4.6 million in the consolidated statement of operations for the year ended December 31, 2021. Finally, the Company also recognized acquisition-related costs of $ 0.9 million within general and administrative expenses in the consolidated statement of operations for the year ended December 31, 2021. For the Contingent Milestone Payments and Contingent Earnout Payments, t he Company recorded contingent consideration liabilities of $ 42.4 million and $ 5.0 million , respectively, representing the fair value of the payment provisions noted as of the Acquisition Date. The Company is required to re-assess the fair value of the Contingent Milestone Payments at each reporting period pursuant to ASC 480 (refer to Note 3). In connection therewith, the Company adjusted the contingent consideration liability for the Contingent Milestone Payments to $ 45.3 million as of December 31, 2021, representing the fair value of the payment provision noted as of the balance sheet date. The Contingent Milestone Payments are payable in common shares based on a fixed amount assigned to each milestone and the weighted average share price of the Company’s stock for the 5-day period prior to the milestone achievement. Accordingly, the number of shares to be issued upon a milestone achievement vary dependent on the Company’s stock price. The settlement amounts of Contingent Milestone Payments are predominantly fixed. If the milestones had been achieved in full on December 31, 2021, the number of shares to be issued would have been 2,817,555 based on a weighted-average per share price of $ 30.17 for the 5-day period prior to December 31, 2021. The Contingent Earnout Payments were not accounted for as derivatives under FASB ASC Topic 815, Derivatives and Hedging and, therefore, are not re-assessed at fair value at each reporting period. The Contingent Earnout Payments will be adjusted when the contingency is resolved and the consideration is paid or becomes payable.

Collaboration and License Arran

Collaboration and License Arrangements	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and License Arrangements	6. Collaboration and License Arrangements Discovery Collaboration Agreement with EQRx, Inc. In August 2021, the Company and EQRx, Inc. (“EQRx”) entered into the Discovery Collaboration Agreement (“Collaboration Agreement”) to discover, develop, and commercialize novel medicines against validated oncology targets. Under the terms of the Collaboration Agreement, the Company is responsible for the discovery collaboration phase through to filing of the application for an Investigational New Drug (“IND”), while EQRx is responsible for clinical development, regulatory and commercialization of the product candidates under the collaboration. Subject to certain opt-out rights, the Company and EQRx share equally in the discovery, development and commercialization costs, as well as the net profits and losses from sales of any collaboration medicines, if approved. The Company retains the right to develop any collaboration medicines in combination with its wholly-owned pipeline. The Company accounts for the Collaboration Agreement pursuant to its accounting policy on collaboration arrangements, as disclosed in Note 2. During the year ended December 31, 2021, expenses related to the Collaboration Agreement were immaterial. Collaboration and License Agreement with Genentech, Inc. On December 11, 2020, the Company entered into the Genentech Agreement, which granted Genentech a license to develop and commercialize RLY-1971. RLY-1971 is currently being developed in a Phase 1a clinical trial for patients with advanced solid tumors (the “Phase 1a Trial”). Unless Genentech elects to exercise its option to conduct the remainder of the ongoing Phase 1a Trial, the Company is responsible for the completion of this trial. Genentech is responsible for conducting all subsequent clinical development of RLY-1971. The Company is also responsible for the one-time transfer of the active pharmaceutical ingredient (“API”) and other materials related to RLY-1971 to Genentech. Under the Genentech Agreement, the Company was entitled to a non-refundable upfront payment of $ 75.0 million, which was due upon completion of certain technology transfer activities and was reflected as accounts receivable on the consolidated balance sheet at December 31, 2020. The Company collected this amount in full in January 2021 . In April 2021, the Company completed the transfer of the IND application for RLY-1971 to Genentech, upon which the Company received payment for the associated non-refundable milestone payment of $ 5.0 million in May 2021. In December 2021, the Company received another milestone payment of $ 15.0 million, which is refundable if the Company opts into the collaboration with Genentech, as discussed below. The Company is eligible to receive up to $ 5.0 million in other near-term milestone payments. The Company is also eligible to receive up to an aggregate of an additional $ 695.0 million upon the achievement of specified development, commercialization and sales-based milestones for RLY-1971 worldwide as well as tiered royalties ranging from low-to-mid teens on annual worldwide net sales of RLY-1971, on a country-by-country basis, subject to reduction in certain circumstances. The Company has the option, exercisable one time at the Company’s sole discretion, to (a) fund half of the development costs of RLY-1971 in the U.S., (b) share half of the net profits or net loss of commercializing RLY-1971 in the U.S. (the “Profit/Cost Share”) and (c) be eligible to receive up to an aggregate of an additional $ 410.0 million upon the achievement of specified commercialization and sales-based milestones for RLY-1971 outside of the U.S and tiered royalties ranging from low-to-mid teens on annual net sales of RLY-1971 outside of the U.S., on a country-by-country basis, subject to reduction in certain circumstances. The Company may elect to opt-out of further participation in the Profit/Cost Share at any time prior to the third anniversary of the first commercial sale of RLY-1971 in the U.S, in which case the financial terms would revert to the terms applicable as if Company had not opted into the Profit/Cost Share as of the effective opt-out date. Genentech may terminate the Genentech Agreement for convenience and the Company may terminate the Genentech Agreement under certain limited circumstances. Unless otherwise terminated, the Genentech Agreement will remain in effect until the expiration of all Genentech’s royalty payment obligations to the Company. Accounting Analysis Identification of the Contract The Company concluded that Genentech is a customer in this arrangement and as such, the arrangement falls within the scope of the revenue recognition guidance in ASC 606. Identification of Performance Obligations At the commencement of the Genentech Agreement, the Company identified the following performance obligations in the agreement: • License to develop and commercialize RLY-1971 and the related know-how; • Research and development services to complete the Phase 1a Trial for RLY-1971; and • Transfer of API and other materials related to RLY-1971. The Company determined that the performance obligations outlined above are both capable of being distinct and distinct within the context of the contract given such rights and activities are independent of each other. The license can be used by Genentech without the research and development services or API outlined above, and similarly those services and inventory provide distinct benefit to Genentech within the context of the contract, separate from the license. Determination of Transaction Price As of December 31, 2021, the Company determined the transaction price for the Genentech Agreement to be $ 86.5 million, which includes both fixed and variable consideration amounts. The total transaction price of $ 86.5 million is comprised of (i) the $ 75.0 million fixed, non-refundable upfront payment, (ii) a $ 5.0 million non-refundable milestone payment due upon the transfer of the IND application to Genentech, (iii) a $ 5.0 million non-refundable milestone payment due upon completion of the Phase 1a Trial for RLY-1971 and (iv) $ 1.5 million of estimated variable consideration related to reimbursements due from Genentech for research and development services. No additional development milestone payments , including the $ 15.0 million milestone payment received in December 2021, and no regulatory milestone payments are included in the transaction price as all such payments are variable consideration fully constrained as of December 31, 2021. As part of management’s evaluation of the constraint, the Company considered numerous factors, including consideration of the fact that achievement of the milestones is outside of the Company’s control, contingent upon Genentech’s efforts and the receipt of regulatory approval and subject to scientific risks of success, as well as the Company’s option to participate in the Profit/Cost Share. Allocation of Transaction Price to Performance Obligations The Company allocated the transaction price of $ 86.5 million based on the stand-alone selling prices (“SSP”) of each of the performance obligations as follows: • $ 83.3 million for the transfer of the license • $ 2.9 million for research and development services; and • $ 0.3 million for the transfer of API. The SSP for the license was determined using an approach that considered discounted, probability-weighted cash flows related to the license transferred. The Company also reviewed comparable market transactions in determining the SSP of the license. The SSP for the research and development services and the transfer of API were based on estimates of the associated effort and cost of these services and cost to manufacture API, adjusted for a reasonable profit margin that would be expected to be realized under similar contracts. Recognition of Revenue The Company is recognizing revenue for each of the three performance obligations as follows: • The Company recognized revenue related to the license at a point in time upon transfer of the license to Genentech. The Company recognized the full amount allocated to the license and related know-how in the fourth quarter of 2020 because the Company had transferred the license upon execution of the Genentech Agreement. • The Company is satisfying the research and development performance obligation for RLY-1971 as the research and development services are performed. The research and development services performance obligation consists of the Company completing the Phase 1a clinical trial initiated in the first quarter of 2020. The Company recognizes revenue related to the research and development services over time using a cost-based input method by calculating actual costs incurred to date at each period end relative to total estimated costs expected to be incurred to fulfill the performance obligation. Revenue recognized related to this performance obligation during the years ended December 31, 2021 and 2020 was $ 1.7 million and $ 0 , respectively. • The Company recognized the full amount of revenue related to the transfer of API in the first quarter of 2021 upon transfer to Genentech in the amount of $ 0.3 million. There was no revenue recognized related to this performance obligation during the year ended December 31, 2020. During the years ended December 31, 2021 and 2020, the Company recognized an aggregate of $ 2.6 million and $ 82.7 million, respectively, of revenue from the Genentech Agreement. At December 31, 2021 , the Company recorded a contract asset in the amount of $ 4.5 million, which is classified as a current asset, on the balance sheet. The contract asset relates to the amount of revenue recognized for which the right to payment is contingent upon conditions other than the passage of time, such as the completion of future milestone activities. At December 31, 2021, the Company recorded an other liability in the amount of $ 15.0 million, which is classified as a non-current liability, on the balance sheet. The liability represents the cash received for the milestone payment in December 2021. The amount has been excluded from the transaction price at December 31, 2021 and, therefore, excluded from amounts recognized as revenue, since the amount is subject to repayment to Genentech if the Company exercises its option to participate in the Profit/Cost Share under the Genentech Agreement.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property Plant And Equipment [Abstract]
Property and Equipment, Net	7. Property and Equipment, Net Property and equipment, net consisted of the following: December 31, 2021 2020 Property and equipment: Laboratory equipment $ 15,797 $ 13,534 Leasehold improvements 2,897 886 Computer equipment 1,093 888 Furniture and fixtures 989 895 Construction in process 134 577 20,910 16,780 Less: accumulated depreciation ( 14,367 ) ( 10,530 ) Total property and equipment, net $ 6,543 $ 6,250 The Company recorded $ 3.9 million, $ 3.5 million and $ 2.8 million of depreciation expense for the years ended December 31, 2021, 2020 and 2019, respectively.

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	8. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: December 31, 2021 2020 External research and development $ 10,755 $ 5,099 Professional services 2,613 464 Other 585 197 Total accrued expenses and other current liabilities $ 13,953 $ 5,760

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2021
Stockholders Equity Note [Abstract]
Common Stock	9. 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 Company’s board of directors. As of December 31, 2021 , no dividends had been declared. In prior years, the Company issued restricted shares of common stock to its founders and non-employees. In addition, the Company issued restricted shares of common stock upon the early exercise of stock options under the Company’s 2016 Stock Option and Grant Plan (the “2016 Stock Plan”). The restrictions on the common shares generally lapse over four years . The Company included the proceeds from the sale of the restricted shares of common stock as a restricted stock liability on the accompanying consolidated balance sheets. Amounts are reclassified to additional paid-in capital as the restrictions lapse. The Company has the right to repurchase any unvested shares of restricted common stock at the original cost in the event of termination. The following table summarizes the restricted stock activity for the year ended December 31, 2021: Shares Weighted- Unvested at December 31, 2020 84,489 $ 0.04 Vested ( 84,489 ) 0.04 Unvested at December 31, 2021 — The fair value of restricted shares that vested during the year ended December 31, 2021 was $ 3.4 million. At-the-Market Offering In August 2021, the Company entered into a sales agreement, (the “Sales Agreement”), with Cowen and Company, LLC, or Cowen, pursuant to which the Company may offer and sell shares of its common stock having aggregate gross proceeds of up to $ 300.0 million from time to time in “at-the-market” offerings through Cowen, as the Company’s sales agent. The Company agreed to pay Cowen a commission of up to 3.0 % of the gross proceeds of any shares sold by Cowen under the Sales Agreement. There have been no shares of common stock sold under the Sales Agreement through December 31, 2021. Follow-On Offering In October 2021, the Company completed a public offering of 15,188,679 shares of common stock, including the exercise in full of the underwriters’ option to purchase an additional 1,981,132 shares, at an offering price of $ 26.50 per share. The Company received net proceeds of $ 382.2 million, after deducting underwriting discounts and commissions and other estimated offering expenses.

Stock Compensation

Stock Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Compensation	10. Stock Compensation In 2016, the Company adopted the 2016 Stock Plan. Subsequent to July 2020, no further awards have been granted under the 2016 Stock Plan and all equity-based awards have been and will continue to be granted under the 2020 Stock Option and Incentive Plan (the “2020 Stock Plan”). To the extent outstanding options granted under the 2016 Stock Plan are cancelled, forfeited, or otherwise terminated without being exercised and would otherwise have been returned to the share reserve under the 2016 Stock Plan, the number of shares underlying such awards will be available for future grant under the 2020 Stock Plan. In 2020, the Company’s stockholders approved the 2020 Stock Plan. All of the Company’s employees, officers, directors, and consultants are eligible to be granted options, restricted stock units, and other stock-based awards under the terms of the 2020 Stock Plan, which originally provided for the issuance of up to 8,376,080 of stock-based awards. The 2020 Stock Plan is also subject to annual increases to be added on the first day of each fiscal year, commencing on January 1, 2021, equal to 5 % of the number of outstanding shares on the immediately preceding December 31 or such lesser number of shares approved by the Company’s board of directors or compensation committee of the board of directors. On January 1, 2021, the number of shares available for issuance under the 2020 Stock Plan was increased by 4,495,341 shares of common stock. There were 9,735,928 stock-based awards available for grant at December 31, 2021 under the 2020 Stock Plan. In 2020, the Company adopted an Employee Stock Purchase Plan (“ESPP”) that permits eligible employees to enroll in six-month offering periods. Participants may purchase shares of the Company’s common stock, through payroll deductions, at a price equal to 85 % of the fair market value of the common stock on the first or last day of the applicable six-month offering period, whichever is lower. Purchase dates under the ESPP occur on or about June 30 and December 31 each year, with the initial purchase date under the ESPP on December 31, 2021. The Company’s stockholders originally authorized 1,092,532 shares for issuance pursuant to the ESPP, which is subject to annual increases to be added on the first day of each fiscal year, commencing on January 1, 2021, equal to the lesser of 2,185,064 shares of the Company’s common stock, 1 % of the number of outstanding shares on the immediately preceding December 31, or an amount determined by the Company’s board of directors. On January 1, 2021, the number of shares available for issuance under the ESPP was increased by 899,068 shares of common stock. There were 1,947,915 shares available for grant at December 31, 2021 under the ESPP. In connection with all stock-based payments, total stock-based compensation expense recognized was as follows: Year Ended December 31, 2021 2020 2019 Research and development expenses $ 24,922 $ 14,691 $ 2,687 General and administrative expenses 23,532 17,269 1,769 $ 48,454 $ 31,960 $ 4,456 Time-Based Stock Options The Company has historically granted stock options to employees, directors and consultants with vesting conditions based on continued service over time. Accordingly, stock-based compensation expense for such awards is recognized using a straight-line attribution model over the vesting term of each option. The following table summarizes activity for time-based stock options under the 2016 Stock Plan and the 2020 Stock Plan for the year ended December 31, 2021: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2020 5,756,578 $ 7.59 7.63 $ 196,634 Granted 2,363,676 34.20 Exercised ( 960,768 ) 4.82 Cancelled ( 253,119 ) 15.37 Outstanding at December 31, 2021 6,906,367 $ 16.80 7.90 $ 111,021 Vested at December 31, 2021 2,971,597 $ 8.24 7.09 $ 68,991 Unvested at December 31, 2021 3,934,770 $ 23.27 8.51 $ 42,029 The total intrinsic value of time-based stock options exercised was $ 32.4 million, $ 2.4 million, and immaterial for the years ended December 31, 2021, 2020 and 2019, respectively. The fair value of each time-based stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model, pursuant to which the weighted-average grant date fair values were $ 22.95 , $ 14.77 , and $ 3.35 during the years ended December 31, 2021, 2020, and 2019, respectively. The following table summarizes the assumptions used in calculating the fair value of the time-based stock options granted. Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.6 - 1.6 % 0.4 - 1.8 % 1.54 - 2.5 % Expected term (in years) 6.3 6.25 6.3 Expected volatility 74.7 - 76.6 % 73.5 - 77.6 % 72.8 - 73.5 % Expected dividend yield 0 % 0 % 0 % The Company uses the simplified method to calculate the expected term, as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for time-based stock options granted. The expected term is applied to the time-based stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among the Company’s employees, directors and consultants. The Company’s stock price volatility assumption is based on historical volatility of a group of companies with similar characteristics to the Company and who have similar risk profiles and positions within the industry. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company accounts for forfeitures as they occur. As of December 31, 2021, the total unrecognized compensation related to unvested time-based stock options granted was $ 53.6 million, which the Company expects to recognize over a weighted-average period of approximately 1.7 years. Performance-Based Stock Options In March 2020 and September 2021, the Company granted options to certain employees with performance-based vesting conditions. In both instances, the commencement of vesting is based on the achievement of various scientific and operational milestones during specified periods, subject to the discretion and approval of either the Company’s board of directors or President and Chief Executive Officer. For the performance-based stock options, the Company applies variable accounting until the performance criteria are determined to be achieved, at which time vesting commences over contractual service periods. Furthermore, because (1) the awards were authorized prior to the accounting grant date in the context of ASC 718, Stock Compensation , (2) the recipients were providing service prior to the accounting grant date, and (3) there were performance conditions that, if not met by the accounting grant date, would have resulted in the forfeiture of the award, the service inception dates preceded the accounting grant date. Ultimately, the stock-based compensation expense for the options is determined based on the fair value of the awards on the accounting grant date, which is then recognized using an accelerated attribution model over the vesting term commencing upon the actual or expected accounting grant date. For the performance-based stock options granted in March 2020, all performance conditions have been resolved and the grant date was set at or prior to December 31, 2020. For the performance-based stock options granted in September 2021, the performance conditions had not been resolved as of December 31, 2021 and, therefore, the Company continued to apply variable accounting through December 31, 2021. The following table summarizes activity for performance-based stock options for the year ended December 31, 2021: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2020 1,940,480 $ 5.22 8.58 $ 70,517 Granted 12,073 33.39 Exercised ( 35,768 ) 5.22 Cancelled ( 103,525 ) 5.22 Outstanding at December 31, 2021 1,813,260 $ 5.41 8.11 $ 45,912 Vested at December 31, 2021 499,464 $ 5.22 8.03 $ 12,731 Unvested at December 31, 2021 1,313,796 $ 5.48 8.14 $ 33,181 The total intrinsic value of performance-based stock options exercised was $ 1.1 million and immaterial for the years ended December 31, 2021 and 2020, respectively. The fair value of each performance-based stock option granted is estimated on the accounting grant date, or at the end of each reporting period if variable accounting is applied, using the Black-Scholes option-pricing model, pursuant to which the grant date fair values were $ 20.28 and $ 37.48 during the years ended December 31, 2021 and 2020, respectively. The assumptions and methodologies used in calculating the fair value of performance-based stock options was similar to the assumptions and methodologies used in calculating the fair value of time-based stock options granted during the years ended December 31, 2021 and 2020. As of December 31, 2021, the total unrecognized compensation related to unvested performance-based stock options granted was $ 21.4 million, which the Company expects to recognize over a weighted-average period of approximately 1.1 years. Restricted Stock Units Starting in 2021, the Company granted restricted stock units (“RSUs”) to employees, directors and consultants under the 2020 Stock Plan. Each of the RSUs represents the right to receive one share of the Company’s common stock upon vesting. The majority of RSUs granted to date have vesting conditions based on continued service over time. Accordingly, stock-based compensation expense for the majority of such awards is recognized using a straight-line attribution model over the vesting term of each RSU. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant. The following table summarizes activity for RSUs under the 2020 Stock Plan for the year ended December 31, 2021: Number of Shares Underlying RSUs Weighted- Unvested at December 31, 2020 — $ — Granted 782,299 33.39 Vested ( 75,875 ) 34.54 Cancelled ( 15,219 ) 37.63 Unvested at December 31, 2021 691,205 34.51 The fair value of restricted shares that vested during the year ended December 31, 2021 was $ 2.6 million. As of December 31, 2021, the total unrecognized compensation related to unvested RSUs granted was $ 22.3 million, which the Company expects to recognize over a weighted-average period of approximately 1.8 years. Employee Stock Purchase Plan The initial offering period under the Company’s ESPP was July 1, 2021 through December 31, 2021, throughout which $ 1.2 million was withheld from employees, on an after-tax basis, in order to purchase 43,685 shares of the Company’s common stock on December 31, 2021. In connection therewith, the Company recognized $ 0.6 million in stock-based compensation expense over the offering period ended December 31, 2021, based on the following assumptions underlying the Black-Scholes option pricing model to estimate the fair value of the option component of the shares purchased under the ESPP. Year Ended December 31, 2021 Risk-free interest rate 0.1 % Expected term (in years) 0.5 Expected volatility 65.1 % Expected dividend yield 0 % As of December 31, 2021, there was no unrecognized compensation expense related to ESPP, since the purchase for the initial offering period under the Company’s offering period was transacted on December 31, 2021.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes During the years ended December 31, 2021, 2020 and 2019 the Company recorded no income tax benefits due to the losses incurred due to the uncertainty of future taxable income. A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2021, 2020 and 2019: December 31, 2021 2020 2019 Income tax computed at federal statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 5.7 % 5.7 % 7.0 % Change in valuation allowance ( 20.5 )% ( 27.3 )% ( 31.0 )% IPR&D ( 7.0 )% — — R&D credit carryovers 2.2 % 7.6 % 4.1 % Stock-based compensation ( 0.4 )% ( 6.7 )% ( 0.9 )% Permanent differences ( 1.0 )% ( 0.3 )% ( 0.2 )% Total 0.0 % 0.0 % 0.0 % The Company’s deferred tax assets and liabilities at December 31, 2021 and 2020, consist of the following: December 31, 2021 2020 Deferred tax assets: Net operating losses $ 108,800 $ 48,832 Tax credit carryforwards 18,288 10,270 Lease liability 6,010 6,430 Intangibles 1,859 1,469 Stock-based compensation 8,374 4,496 Depreciation and amortization 477 230 Other 4,304 14 Total gross deferred tax asset 148,112 71,741 Valuation allowance ( 142,674 ) ( 65,813 ) Net deferred tax asset 5,438 5,928 Deferred tax liability Operating lease assets ( 5,438 ) ( 5,928 ) Total deferred tax liability ( 5,438 ) ( 5,928 ) $ — $ — The Company has incurred net operating losses (“NOL”) since inception. As of December 31, 2021 and 2020, the Company had federal NOL carryforwards of $ 371.4 million and $ 174.0 million, respectively, available to reduce taxable income, of which $ 43.1 million expire beginning in 2035 and $ 328.3 million do not expire. The Company has state NOL carryforwards of $ 466.2 million and $ 192.3 million as of December 31, 2021 and 2020, respectively, available to reduce future state taxable income, which expire at various dates beginning in 2035 . As of December 31, 2021 and 2020, the Company also had available federal research and development tax credit carryforwards of $ 14.9 million and $ 8.1 million, respectively, available to reduce future tax liabilities, which begin to expire beginning in 2035 . The Company also has state research and development tax credit carryforwards of $ 4.2 million and $ 2.7 million as of December 31, 2021 and 2020, respectively, available to reduce future state tax liabilities, which expire at various dates beginning in 2030 . Utilization of NOL and research and development credit carryforwards may generally be subject to limitation under Sections 382 and 383 of the Internal Revenue Code of 1986 (“Sections 382 and 383”) due to ownership changes that have occurred previously, or that could occur in the future. These ownership changes may limit the amount of NOL and research and development credit carryforwards that can be utilized annually to offset any post-ownership change taxable income and tax, respectively. The latest Section 382 study was performed by the Company through December 31, 2021, through which it was noted that a historic ownership change has likely occurred. Nonetheless, the Company has determined that, as of December 31, 2021, the prospective utilization of all net operating loss and tax credit carryforwards generated from inception through December 31, 2021 and, therefore, the corresponding Federal and Massachusetts deferred tax assets, should not be restricted by Sections 382 and 383, although ownership changes after December 31, 2021 could impact the Company’s ability to utilize these tax attributes in the future. The Company recorded a valuation allowance against its deferred tax assets for the years ended December 31, 2021 and 2020 because the Company’s management believes that it is more likely than not that these assets will not be realized. The valuation allowance increased by approximately $ 76.9 million and $ 14.3 million for the years ended December 31, 2021 and 2020, respectively, primarily as a result of operating losses generated with no corresponding financial statement benefit. The Company had no unrecognized tax benefits as of December 31, 2021 and 2020. 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. There are currently no pending tax examinations. The Company’s tax years are still open under statute from inception to the present. In response to the COVID-19 pandemic, the Coronavirus Aid, Relief and Economic Security Act (CARES Act) was signed into law in March 2020. The CARES Act lifts certain deduction limitations originally imposed by the Tax Cuts and Jobs Act of 2017 (“2017 Tax Act”). Corporate taxpayers may carryback NOLs originating during 2018 through 2020 for up to five years , which was not previously allowed under the 2017 Tax Act. The CARES Act also eliminates the 80 % of taxable income limitations by allowing corporate entities to fully utilize NOL carryforwards to offset taxable income in 2018, 2019 or 2020. Taxpayers may generally deduct interest up to the sum of 50 % of adjusted taxable income plus business interest income ( 30 % limit under the 2017 Tax Act) for tax years beginning January 1, 2019 and 2020. The CARES Act allows taxpayers with alternative minimum tax credits to claim a refund in 2020 for the entire amount of the credits instead of recovering the credits through refunds over a period of years, as originally enacted by the 2017 Tax Act. In addition, the CARES Act raises the corporate charitable deduction limit to 25 % of taxable income and makes qualified improvement property generally eligible for 15-year cost-recovery and 100 % bonus depreciation. The enactment of the CARES Act did not result in any adjustments to the Company’s income tax provision for the year ended December 31, 2021, or to the Company’s net deferred tax assets as of December 31, 2021 , since the Company has no t recorded any U.S. federal or state income tax benefits for the net losses incurred in any year due to the uncertainty of realizing a benefit from those items.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	12. Net Loss Per Share The following table summarizes the computation of basic and diluted net loss per share of the Company: Year Ended December 31, 2021 2020 2019 Net loss $ ( 363,872 ) $ ( 52,412 ) $ ( 75,305 ) Deemed dividend resulting from extinguishment upon modification of Series C preferred stock — ( 177,789 ) — Net loss attributable to common stockholders $ ( 363,872 ) $ ( 230,201 ) $ ( 75,305 ) Net loss attributable to common stockholders per share, basic and diluted $ ( 3.82 ) $ ( 5.40 ) $ ( 21.82 ) Weighted average shares of common stock, basic and diluted 95,136,719 42,619,582 3,450,500 On July 8, 2020, the Company’s board of directors and its Series C preferred stockholders approved an amendment to the conversion preferences and rights of the Series C preferred stock which, among other changes, resulted in a reduction in the conversion price of the Series C preferred stock from $ 3.21 to $ 3.027603 . The changes to the conversion feature were considered to be a significant change to the substantive contractual terms of the Series C preferred stock and, therefore, the Company accounted for the changes as an extinguishment and reissuance of the Series C preferred stock. In accordance with SEC staff guidance codified in ASC 260-10-S99-2, when equity classified preferred shares are extinguished, the difference between (1) the fair value of the consideration transferred to the holders of the preferred shares and (2) the carrying amount of the preferred shares, net of issuance costs, is subtracted from (or added back to) net income to arrive at income available to common stockholders in the calculation of earnings per share. This difference between the fair value of consideration transferred and carrying amount of the preferred shares, also referred to as a “deemed dividend”, was therefore added back to net loss above to derive net loss attributable to common stockholders. The Company’s potentially dilutive securities, which include options to purchase common stock, restricted stock units and unvested restricted stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share 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 for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 2019 Convertible preferred stock — — 59,883,877 Options to purchase common stock 8,719,627 7,697,058 5,306,176 Unvested restricted stock — 84,489 679,158 Unvested restricted stock units 691,205 — — 9,410,832 7,781,547 65,869,211

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Intellectual Property License The Company has a Collaboration and License Agreement with D. E. Shaw Research, LLC (“D. E. Shaw Research”), which held 9,999,999 shares of Series A preferred stock and 1,557,875 shares of Series C preferred stock at December 31, 2019. Upon the IPO these shares were converted into 3,281,253 shares of common stock, which are outstanding at December 31, 2021. The agreement provides that the parties will jointly conduct research efforts with the goal of identifying and developing product candidates. The original term of the agreement was three years and required the Company to pay an annual fee of $ 1.0 million. On June 15, 2020, the Company and D. E. Shaw Research agreed to amend the Collaboration and License Agreement (the “Amended and Restated Collaboration and License Agreement”). The Amended and Restated Collaboration and License Agreement extended the term of the agreement to August 16, 2025 and increased the annual fee from $ 1.0 million to $ 9.9 million. The Amended and Restated Collaboration and License Agreement automatically renews for successive one year periods unless either party provides at least one year notice of non-renewal, and the annual fee during each of the one year renewal terms is subject to the mutual agreement of the Company and D. E. Shaw Research. The Company is obligated to pay potential development milestone payments under the terms of the agreement up to $ 7.3 million per target, plus sales milestones and royalties, upon the achievement of certain specified contingent events. Such payments for achievement of development and regulatory milestones total up to $ 7.3 million in the aggregate for each of the first three products the Company develops, and up to $ 6.3 million in the aggregate for each product the Company develops after the first three. The Company assessed the milestone and royalty events under the Amended and Restated Collaboration and License Agreement as of December 31, 2021 and 2020 and concluded that $ 1.5 million was due related to the execution of the Genentech Agreement as of December 31, 2020 and no such payments were due as of December 31, 2021. The Company recorded research and development expense of $ 9.5 million, $ 6.4 million and $ 1.5 million under this agreement for the years ended December 31, 2021, 2020 and 2019, respectively. At December 31, 2021 and December 31, 2020 , the Company had a prepaid balance to D. E. Shaw Research of approximately $ 4.4 million and an accrued expense balance of approximately $ 1.5 million, respectively, on its balance sheets. Other Research Arrangements The Company has certain other research and license arrangements with third-parties, which provide the Company with research services with the goal of identifying and developing product candidates. The Company is obligated to pay development milestone payments for up to four targets, each in the range of $ 4.0 million to $ 7.0 million upon the achievement of certain specified contingent events. The Company assessed the milestones at December 31, 2021 and 2020 and concluded that $ 0.5 million was due as of December 31, 2021 and no such payments were due as of December 31, 2020. The Company incurred approximately $ 5.4 million, $ 2.7 million and $ 3.5 million of research and development expense under these agreements in the years ended December 31, 2021, 2020 and 2019, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	14. Leases 399 Binney Street In December 2017, the Company entered into a facility lease agreement for approximately 44,336 square feet of office and laboratory space at 399 Binney Street, Cambridge, Massachusetts, which was increased to 44,807 square feet in January 2018. The Company gained control of the leased space in January 2019 and recorded a right of use asset and a lease liability, accordingly. The lease expires in April 2029 , subject to certain renewal options, which have not been included in the Company’s right of use asset and liability, as the Company is not reasonably certain to exercise those options. In September 2020, the Company entered into an amendment to its facility lease agreement to expand the leased area by approximately 1,824 square feet of office space at 399 Binney Street, Cambridge, Massachusetts. The amended lease expires in April 2029, subject to certain renewal options. The amendment to the lease agreement met the criteria to be accounted for as a separate lease. The Company gained control of the leased space in October 2020 and recorded a right of use asset and a lease liability, accordingly. The right of use asset and lease liability recorded in connection with this amendment were not material. As discussed in Note 2, the Company provided a letter of credit in the amount of $ 0.9 million with a financial institution, which expires September 30, 2028 . The following table summarizes the presentation of amounts recorded on the Company’s consolidated balance sheets for the operating lease at 399 Binney Street: December 31, Balance sheet location 2021 2020 Assets: Operating lease assets Operating lease assets $ 20,780 $ 22,579 Liabilities: Current operating lease Operating lease liabilities $ 1,844 $ 1,521 Non-current operating lease Operating lease liabilities, net of current portion 21,056 22,901 Total lease liabilities $ 22,900 $ 24,422 The following table summarizes the effect of lease costs for the Company’s operating lease at 399 Binney Street on Company’s consolidated statements of operations and comprehensive loss for the years ended December 31, 2021, 2020 and 2019: Year Ended December 31, Statement of operations location 2021 2020 2019 Operating lease costs Research and development $ 3,262 $ 3,273 $ 3,216 General and administrative 846 748 581 Total operating lease cost $ 4,108 $ 4,021 $ 3,797 The Company made cash payments of $ 5.4 million, $ 4.9 million and $ 2.6 million under the lease agreement for 399 Binney Street during the years ended December 31, 2021, 2020 and 2019, respectively. The minimum lease payments for the Company’s operating lease at 399 Binney Street as of December 31, 2021 for the next five years and thereafter is expected to be as follows: Year Ending December 31, Amount 2022 4,134 2023 4,254 2024 4,377 2025 4,503 2026 4,634 Thereafter 11,325 Total lease payments 33,227 Less: interest ( 10,327 ) Present value of operating lease liabilities $ 22,900 The weighted average remaining lease term and weighted average discount rate of the operating lease were 7.3 years and 10.4 %, respectively, at December 31, 2021 for the Company’s operating lease at 399 Binney Street . The weighted average remaining lease term and weighted average discount rate of the operating lease were 8.3 years and 10.4 %, respectively, at December 31, 2020 for the Company’s operating lease at 399 Binney Street. 60 Hampshire Street On May 26, 2021, the Company entered into a lease agreement for laboratory and office space located at 60 Hampshire Street, Cambridge, Massachusetts (the “Hampshire Lease”). Under the terms of the Hampshire Lease, the Company will lease approximately 41,474 square feet as the sole tenant, which will supplement the Company’s current leased premises at 399 Binney Street, Cambridge, Massachusetts. The landlord will contribute an aggregate of $ 6.2 million toward the cost of construction and tenant improvements for the premises. In total, fixed lease payments, which include base rent, landlord fees, and parking, are $ 55.7 million over the lease term. The Company’s obligation to pay rent under the Hampshire Lease will start on a date set forth in an estimated construction schedule pursuant to the Hampshire Lease or the date on which the landlord tenders possession of the premises to the Company with the tenant improvements substantially completed, whichever occurs later. The term of the Hampshire Lease is ten years following the rent commencement, which is currently expected in 2022. The Company did not control the space or any of the assets being constructed therein as of December 31, 2021 and further concluded the improvements being constructed therein are the landlord’s assets with alternative use to future tenants. As such, no right of use asset or lease liability was recorded on the consolidated balance sheet at December 31, 2021, since lease commencement, for accounting purposes, had not been triggered. As discussed in Note 2, the Company provided a letter of credit in connection with the Hampshire Lease in the amount of $ 1.7 million with a financial institution, which expires August 31, 2033 .

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2021
Postemployment Benefits [Abstract]
Retirement Benefits	15. Employee Benefits In 2016, the Company established a defined-contribution plan under Section 401(k) of the Internal Revenue Code (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. The Company made matching contributions to the 401(k) Plan of $ 1.2 million for the year ended December 31, 2021 . The Company was not required to make and did not make any matching contributions to the 401(k) Plan for the years ended December 31, 2020 and 2019.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events In preparing the consolidated financial statements as of December 31, 2021 , the Company evaluated subsequent events for recognition and measurement purposes through the filing date of this Annual Report on Form 10-K. The Company concluded that no events or transactions have occurred that require disclosure in the accompanying consolidated financial statements.

Significant Accounting Policies

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 pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for reporting on Form 10-K. The Company’s consolidated financial statements include the accounts of Relay Therapeutics, Inc. and its wholly-owned subsidiaries, Relay Therapeutics Securities Corporation and Relay ML Discovery, LLC. All intercompany balances and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual of research and development and manufacturing expenses, the valuation of equity instruments, the determination of the transaction price and standalone selling price of performance obligations under Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606, Revenue from Contracts with Customers ("ASC 606"), the incremental borrowing rate for determining the operating lease assets and liabilities and the fair value of contingent consideration and the fair value of net assets acquired in the acquisition of ZebiAI Therapeutics, Inc. (“ZebiAI”). Estimates are periodically reviewed in light of changes in circumstances, facts and experience.
Segment Information	Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on using innovative experimental and computational approaches on protein motion for making medicines to drug protein targets that have previously been intractable or inadequately addressed. The Company operates in the United States and all tangible assets are held in the United States.
Cash Equivalents	Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market funds, are stated at fair value.
Restricted Cash	Restricted Cash The Company had restricted cash of $ 2.6 million and $ 0.9 million as of December 31, 2021 and 2020 , respectively, to secure letters of credit in connection with the leases of the Company’s facilities (see Note 14). The Company classified the restricted cash as a noncurrent asset on its consolidated balance sheets, consistent with the terms of the underlying lease agreements.
Investments	Investments Investments in marketable securities are classified as available-for-sale. Available-for-sale 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 securities are reported as a separate component of stockholders’ equity. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. All of the Company’s available-for-sale securities are available to the Company for use in current operations. As a result, the Company classified all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the consolidated statements of operations and comprehensive loss. If any adjustment is required to reflect a decline in the value of the investment that the Company considers to be “other than temporary”, the Company recognizes a charge to the consolidated statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.
Concentration of Credit Risk and Significant Suppliers	Concentration of Credit Risk and Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and investments. From time to time, the Company has maintained all of its cash, cash equivalents and investments at certain accredited financial institutions in amounts that exceed federally insured limits. The Company generally invests its excess capital in money market funds, U.S. treasury bonds, U.S. treasury bills and agency bonds, all of which are subject to minimal credit and market risk. Management has established guidelines relative to credit ratings and maturities intended to safeguard principal balances and maintain liquidity. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. The Company is dependent on third-party suppliers for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relies and expects to continue to rely on a small number of these suppliers, including D. E. Shaw Research, LLC as discussed in Note 13, to meet its requirements for its programs. These programs could be adversely affected by a significant interruption in pre-clinical and clinical testing and the supply of active pharmaceutical ingredients and formulated drugs.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.
Revenue Recognition	Revenue Recognition The Company accounts for revenue recognition in accordance with ASC 606, Revenue from Contracts with Customers . Under ASC 606, an entity 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 an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with customer(s); (ii) identify the performance obligation(s) in the contract(s); (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract(s); and (v) recognize revenue when (or as) the entity satisfies a performance obligation. 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 and determines those that are performance obligations. The Company then determines the transaction price and allocates it to the performance obligations. As part of the accounting for these arrangements, the Company must use significant judgment to determine: (a) the number of performance obligations based on the determination under step (ii) above; (b) the transaction price under step (iii) above, including the determination of whether milestones or other variable consideration should be included in the transaction price; and (c) the stand-alone selling price for each performance obligation identified in the contract for the allocation of the transaction price in step (iv) above. The Company utilizes key assumptions and judgments to determine the stand-alone selling price for each performance obligation, which may include discounted cash flow models, evaluation of comparable transactions, pricing considered in negotiating the transaction and estimated costs, to determine how the transaction price is allocated among the performance obligations . The Company uses judgment to determine whether milestones or other variable consideration should be included in the transaction price. As part of management’s evaluation of the transaction price, the Company considers numerous factors, including whether the achievement of the milestones is outside of our control, contingent upon the efforts of others or subject to scientific risks of success. If the Company concludes it is probable that a significant revenue reversal would not occur, the associated milestone payment is included in the transaction price. Milestone payments that are not within our control, such as regulatory approvals, are generally not considered probable until those milestones are achieved. The Company re-evaluates the transaction price, including estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. For revenue-based royalties, including milestone payments based on the level of sales, the Company will include royalties in the transaction price at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty is allocated has been satisfied (or partially satisfied). Once the performance obligations are identified, the transaction price is allocated to each performance obligation based on the relative stand-alone selling price. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied, either at a point in time or over time. If the performance obligation is satisfied over time, the Company recognizes revenue based on the use of either an output or input method. Collaboration Agreements The Company enters into collaborative agreements with third parties to research, develop and commercialize drug candidates, pursuant to which the risks and rewards for such activities are shared between the parties. Such arrangements also provide for cost sharing between the parties during the research and development phase, as well as potential future profit share payments during the commercialization phase. In general, such contracts are evaluated under the provisions of FASB ASC 808, Collaborative Arrangements (“ASC 808”). The amounts receivable and payable for research and development activities are presented net within research and development expense on the consolidated statement of operations, as such the net costs reflect the Company’s share of the ongoing research and development efforts. The amounts receivable and payable for commercialization activities are presented net as either collaboration revenue, separate from revenue from contracts with customers, or collaboration expense on the consolidated statement of operations, as appropriate.
Collaboration Agreements	Collaboration Agreements The Company enters into collaborative agreements with third parties to research, develop and commercialize drug candidates, pursuant to which the risks and rewards for such activities are shared between the parties. Such arrangements also provide for cost sharing between the parties during the research and development phase, as well as potential future profit share payments during the commercialization phase. In general, such contracts are evaluated under the provisions of FASB ASC 808, Collaborative Arrangements (“ASC 808”). The amounts receivable and payable for research and development activities are presented net within research and development expense on the consolidated statement of operations, as such the net costs reflect the Company’s share of the ongoing research and development efforts. The amounts receivable and payable for commercialization activities are presented net as either collaboration revenue, separate from revenue from contracts with customers, or collaboration expense on the consolidated statement of operations, as appropriate.
Lease Agreements	Lease Agreements Under ASC 842, Leases , the Company determines if an arrangement is or contains a lease at inception. For leases with a term of 12 months or less, the Company does not recognize a right-of-use asset or lease liability. The Company’s operating leases are recognized on its consolidated balance sheets as other noncurrent assets, other current liabilities and other noncurrent liabilities. The Company does not have any finance leases. Right-of-use 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 right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an estimate of its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. Operating lease right-of-use assets also include the effect of any lease payments made prior to commencement and excludes lease incentives. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components, which are accounted for as a combined element.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the useful life of the asset. Laboratory and computer equipment are depreciated over three years . Furniture and fixtures are depreciated over five years . Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company continually evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book values of the assets to the expected future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured in an amount by which the book values of the assets exceed their fair value. The Company did no t recognize any impairment losses for the years ended December 31, 2021, 2020 and 2019.
Stock-Based Compensation	Stock-Based Compensation The Company measures stock options and other stock-based awards granted to employees, directors and non-employees based on their fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. The Company recognizes the impact of forfeitures on stock-based compensation expense as forfeitures occur. The Company estimates the fair value of each stock option grant on the date of grant using the Black-Scholes option-pricing model, which uses as inputs the fair value of the Company’s common stock and assumptions the Company makes for the volatility of its common stock, the expected term of the stock options, the risk-free interest rate for a period that approximates the expected term of the stock options and the expected dividend yield. Prior to the Company’s IPO, the estimated fair value of its common stock was determined by the board of directors, or compensation committee thereof, as of the date of each option grant, with input from management, considering the most recently available third-party valuations of common stock and the board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of the grant. Historically, these independent third-party valuations of the Company’s equity instruments were performed contemporaneously with identified value inflection points. These third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “Practice Aid”). The Practice Aid identifies various available methods for allocating the enterprise value across classes of series of capital stock in determining the fair value of the Company’s common stock at each valuation date. Following the Company’s IPO, in connection with the accounting for granted stock options and other awards the Company may grant, the fair value of the Company’s common stock is determined based on the quoted market price of its common stock.
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 pre-clinical studies and clinical trials. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made.
Research and Manufacturing Contracts	Research and Manufacturing Contracts The Company has entered into various research and development contracts with research institutions and other companies whose costs are included in research and development expense in the accompanying consolidated statements of operations and comprehensive loss. These agreements are generally cancelable and related payments are recorded as research and development expenses as the underlying services are performed. When evaluating the adequacy of the expense recognized, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Judgments and estimates are made in determining the expense recognized and the related prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical estimates have not been materially different from the actual costs.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.
Acquired In-Process Research and Development	Acquired In-Process Research and Development In an asset acquisition, the cost allocated to acquire in-process research and development (“IPR&D”) with no alternative future use is charged to expense at the acquisition date. Refer to Note 5, Acquisition of ZebiAI, for a more detailed description of the accounting policies applied to the asset acquisition.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the Company’s financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax bases of the assets and liabilities using the enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance against deferred tax assets is recorded if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. 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 the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2021, 2020 and 2019, other comprehensive income (loss) consisted of changes in unrealized gains and losses from available-for-sale investments.
Net Loss Per Common Share	Net Loss Per Common Share Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and the effect of dilutive securities. The Company applies the two-class method to calculate its basic and diluted net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. The Company’s participating securities contractually entitle the holders of such shares to participate in dividends; but do not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. Additionally, in periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. For additional discussion of net loss per common share, please see Note 12, Net Loss Per Share.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company adopted Accounting Standards Update (“ASU”) No. 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). This standard amends the guidance on convertible instruments and the derivatives scope exception for contracts in an entity’s own equity and amends the related earnings per share (“EPS”) guidance. The Company adopted this standard on January 1, 2021 and the adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures. The Company adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends certain aspects of the existing guidance to improve consistent application. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures.
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Issued Accounting Pronouncements Not Yet Adopted 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”). This standard requires that credit losses be reported as an allowance using an expected losses model, representing the entity’s current estimate of credit losses expected to be incurred. The accounting guidance in effect for the Company through December 31, 2021 is based on an incurred losses model. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The Company adopted this standard on January 1, 2022. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements or disclosures .

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 and Liabilities Measured at Fair Value on a Recurring Basis and Level of the Fair Value Hierarchy	The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values: Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 251,891 $ — $ — $ 251,891 Investments: US treasury bills — 469,386 — 469,386 US agency securities — 208,568 — 208,568 Total investments — 677,954 — 677,954 Total assets $ 251,891 $ 677,954 $ — $ 929,845 Liabilities Contingent Milestone Payments $ — $ — $ 45,258 $ 45,258 Total liabilities $ — $ — $ 45,258 $ 45,258 Fair Value Measurements as of Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market funds $ 447,146 $ — $ — $ 447,146 Investments: US treasury bills — 33,026 — 33,026 US agency securities — 197,389 — 197,389 Total investments — 230,415 — 230,415 Total $ 447,146 $ 230,415 $ — $ 677,561
Schedule of Changes in Fair Value of Contingent Consideration Liability	The following table reconciles the change in fair value of the contingent consideration liability (in thousands): Year Ended December 31, 2021 Balance at December 31, 2020 $ — Contingent Milestone Payments related to acquisition of ZebiAI 42,422 Contingent Earnout Payments related to acquisition of ZebiAI 5,000 Increase in fair value of Contingent Milestone Payments 2,836 Balance at December 31, 2021 $ 50,258

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2021
Schedule Of Investments [Abstract]
Summary of Fair Value of Available-for-Sale Investments by Type of Security	The fair value of available-for-sale investments by type of security was as follows: December 31, 2021 Amortized Unrealized Unrealized Fair Investments: U.S treasury bills $ 189,406 $ ( 228 ) $ 189,178 U.S agency securities 108,895 ( 138 ) 108,757 Total investments with a maturity of one year or less 298,301 — ( 366 ) 297,935 U.S treasury bills 280,743 ( 535 ) 280,208 U.S agency securities 99,998 ( 187 ) 99,811 Total investments with a maturity of one to two years 380,741 — ( 722 ) 380,019 Total investments $ 679,042 $ — $ ( 1,088 ) $ 677,954 December 31, 2020 Amortized Unrealized Unrealized Fair Investments: U.S treasury bills $ 29,997 $ 21 $ — $ 30,018 U.S agency securities 20,996 5 — 21,001 Total investments with a maturity of one year or less 50,993 26 — 51,019 U.S treasury bills 3,008 — — 3,008 U.S agency securities 176,350 38 — 176,388 Total investments with a maturity of one to two years 179,358 38 — 179,396 Total investments $ 230,351 $ 64 $ — $ 230,415

Acquisition of ZebiAI (Tables)

Acquisition of ZebiAI (Tables)	1 Months Ended
	Jan. 31, 2021
Business Combination, Description [Abstract]
Summary of Net Assets Acquired Based on Estimated Fair Values	The following table summarizes the net assets acquired based on their estimated fair values as of the Acquisition Date (in thousands): Acquired IPR&D asset $ 123,000 Loss on initial consolidation of VIE 11,855 Assets obtained in asset acquisition 662 Liabilities assumed in asset acquisition ( 2,330 ) Intangible asset 2,300 Net acquired assets $ 135,487

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: December 31, 2021 2020 Property and equipment: Laboratory equipment $ 15,797 $ 13,534 Leasehold improvements 2,897 886 Computer equipment 1,093 888 Furniture and fixtures 989 895 Construction in process 134 577 20,910 16,780 Less: accumulated depreciation ( 14,367 ) ( 10,530 ) Total property and equipment, net $ 6,543 $ 6,250

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: December 31, 2021 2020 External research and development $ 10,755 $ 5,099 Professional services 2,613 464 Other 585 197 Total accrued expenses and other current liabilities $ 13,953 $ 5,760

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2021
Stockholders Equity Note [Abstract]
Summary Of The Restricted Stock Activity	The following table summarizes the restricted stock activity for the year ended December 31, 2021: Shares Weighted- Unvested at December 31, 2020 84,489 $ 0.04 Vested ( 84,489 ) 0.04 Unvested at December 31, 2021 —

Stock Compensation (Tables)

Stock Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Total Stock-based Compensation Expense Recognized	In connection with all stock-based payments, total stock-based compensation expense recognized was as follows: Year Ended December 31, 2021 2020 2019 Research and development expenses $ 24,922 $ 14,691 $ 2,687 General and administrative expenses 23,532 17,269 1,769 $ 48,454 $ 31,960 $ 4,456
Schedule of Estimated Fair Value of Stock Options	The following table summarizes the assumptions used in calculating the fair value of the time-based stock options granted. Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.6 - 1.6 % 0.4 - 1.8 % 1.54 - 2.5 % Expected term (in years) 6.3 6.25 6.3 Expected volatility 74.7 - 76.6 % 73.5 - 77.6 % 72.8 - 73.5 % Expected dividend yield 0 % 0 % 0 %
Schedule of Restricted Stock Units Activity	The following table summarizes activity for RSUs under the 2020 Stock Plan for the year ended December 31, 2021: Number of Shares Underlying RSUs Weighted- Unvested at December 31, 2020 — $ — Granted 782,299 33.39 Vested ( 75,875 ) 34.54 Cancelled ( 15,219 ) 37.63 Unvested at December 31, 2021 691,205 34.51
Schedule of Estimated Fair Value of Employee Stock Purchase Plan	In connection therewith, the Company recognized $ 0.6 million in stock-based compensation expense over the offering period ended December 31, 2021, based on the following assumptions underlying the Black-Scholes option pricing model to estimate the fair value of the option component of the shares purchased under the ESPP. Year Ended December 31, 2021 Risk-free interest rate 0.1 % Expected term (in years) 0.5 Expected volatility 65.1 % Expected dividend yield 0 %
Time-Based Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Stock Option Activity	The following table summarizes activity for time-based stock options under the 2016 Stock Plan and the 2020 Stock Plan for the year ended December 31, 2021: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2020 5,756,578 $ 7.59 7.63 $ 196,634 Granted 2,363,676 34.20 Exercised ( 960,768 ) 4.82 Cancelled ( 253,119 ) 15.37 Outstanding at December 31, 2021 6,906,367 $ 16.80 7.90 $ 111,021 Vested at December 31, 2021 2,971,597 $ 8.24 7.09 $ 68,991 Unvested at December 31, 2021 3,934,770 $ 23.27 8.51 $ 42,029
Performance-Based Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Stock Option Activity	The following table summarizes activity for performance-based stock options for the year ended December 31, 2021: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2020 1,940,480 $ 5.22 8.58 $ 70,517 Granted 12,073 33.39 Exercised ( 35,768 ) 5.22 Cancelled ( 103,525 ) 5.22 Outstanding at December 31, 2021 1,813,260 $ 5.41 8.11 $ 45,912 Vested at December 31, 2021 499,464 $ 5.22 8.03 $ 12,731 Unvested at December 31, 2021 1,313,796 $ 5.48 8.14 $ 33,181

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Reconciliation of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Effective Income Tax Rate	A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2021, 2020 and 2019: December 31, 2021 2020 2019 Income tax computed at federal statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 5.7 % 5.7 % 7.0 % Change in valuation allowance ( 20.5 )% ( 27.3 )% ( 31.0 )% IPR&D ( 7.0 )% — — R&D credit carryovers 2.2 % 7.6 % 4.1 % Stock-based compensation ( 0.4 )% ( 6.7 )% ( 0.9 )% Permanent differences ( 1.0 )% ( 0.3 )% ( 0.2 )% Total 0.0 % 0.0 % 0.0 %
Summary of Deferred Tax Assets and Liabilities	The Company’s deferred tax assets and liabilities at December 31, 2021 and 2020, consist of the following: December 31, 2021 2020 Deferred tax assets: Net operating losses $ 108,800 $ 48,832 Tax credit carryforwards 18,288 10,270 Lease liability 6,010 6,430 Intangibles 1,859 1,469 Stock-based compensation 8,374 4,496 Depreciation and amortization 477 230 Other 4,304 14 Total gross deferred tax asset 148,112 71,741 Valuation allowance ( 142,674 ) ( 65,813 ) Net deferred tax asset 5,438 5,928 Deferred tax liability Operating lease assets ( 5,438 ) ( 5,928 ) Total deferred tax liability ( 5,438 ) ( 5,928 ) $ — $ —

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss Per Share	The following table summarizes the computation of basic and diluted net loss per share of the Company: Year Ended December 31, 2021 2020 2019 Net loss $ ( 363,872 ) $ ( 52,412 ) $ ( 75,305 ) Deemed dividend resulting from extinguishment upon modification of Series C preferred stock — ( 177,789 ) — Net loss attributable to common stockholders $ ( 363,872 ) $ ( 230,201 ) $ ( 75,305 ) Net loss attributable to common stockholders per share, basic and diluted $ ( 3.82 ) $ ( 5.40 ) $ ( 21.82 ) Weighted average shares of common stock, basic and diluted 95,136,719 42,619,582 3,450,500
Summary of Antidilutive Securities Excluded From Computation of Earnings Per Share	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 for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 2019 Convertible preferred stock — — 59,883,877 Options to purchase common stock 8,719,627 7,697,058 5,306,176 Unvested restricted stock — 84,489 679,158 Unvested restricted stock units 691,205 — — 9,410,832 7,781,547 65,869,211

Leases (Tables)

Leases (Tables) - 399 Binney Street [Member]	12 Months Ended
	Dec. 31, 2021
Operating Leased Assets [Line Items]
Schedule of Operating Leases Presentation in Consolidated Balance Sheets	The following table summarizes the presentation of amounts recorded on the Company’s consolidated balance sheets for the operating lease at 399 Binney Street: December 31, Balance sheet location 2021 2020 Assets: Operating lease assets Operating lease assets $ 20,780 $ 22,579 Liabilities: Current operating lease Operating lease liabilities $ 1,844 $ 1,521 Non-current operating lease Operating lease liabilities, net of current portion 21,056 22,901 Total lease liabilities $ 22,900 $ 24,422
Summary of Operating Lease Presentation in Consolidated Statements of Operations and Comprehensive Loss	The following table summarizes the effect of lease costs for the Company’s operating lease at 399 Binney Street on Company’s consolidated statements of operations and comprehensive loss for the years ended December 31, 2021, 2020 and 2019: Year Ended December 31, Statement of operations location 2021 2020 2019 Operating lease costs Research and development $ 3,262 $ 3,273 $ 3,216 General and administrative 846 748 581 Total operating lease cost $ 4,108 $ 4,021 $ 3,797
Summary of Future Minimum Lease Payments	The minimum lease payments for the Company’s operating lease at 399 Binney Street as of December 31, 2021 for the next five years and thereafter is expected to be as follows: Year Ending December 31, Amount 2022 4,134 2023 4,254 2024 4,377 2025 4,503 2026 4,634 Thereafter 11,325 Total lease payments 33,227 Less: interest ( 10,327 ) Present value of operating lease liabilities $ 22,900

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	Dec. 31, 2021USD ($)Program	Dec. 31, 2020USD ($)
Nature of Business and Basis of Presentation [Line Items]
Number of discovery stage programs | Program	5
Accumulated deficit | $	$ (768,100)	$ (404,228)

Significant Accounting Polici_2

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021USD ($)Segment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments | Segment	1
Maturity days for highly liquid investments	The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents.
Restricted cash	$ 2,578,000	$ 878,000
Operating lease option to extent	true
Operating lease option to terminate	true
Impairment loss of long lived assets	$ 0	0	$ 0
Description of Income tax benefit, likelihood of realized upon ultimate settlement	greater than 50%
Laboratory and Computer Equipment [Member]
Significant Accounting Policies [Line Items]
Property and equipment, useful life	3 years
Furniture and Fixtures [Member]
Significant Accounting Policies [Line Items]
Property and equipment, useful life	5 years
Letter of Credit [Member]
Significant Accounting Policies [Line Items]
Restricted cash	$ 2,600,000	$ 900,000

Fair Value of Financial Asset_2

Fair Value of Financial Assets - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis and Level of the Fair Value Hierarchy (Detail) - Fair value on a recurring basis [Member] - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investments:
Total assets	$ 929,845	$ 677,561
Liabilities
Contingent Milestone Payments	45,258
Total liabilities	45,258
Investments [Member]
Investments:
Total investments	677,954	230,415
Investments [Member] | US treasury bills [Member]
Investments:
Total investments	469,386	33,026
Investments [Member] | US agency securities [Member]
Investments:
Total investments	208,568	197,389
Level 1 [Member]
Investments:
Total assets	251,891	447,146
Level 2 [Member]
Investments:
Total assets	677,954	230,415
Level 2 [Member] | Investments [Member]
Investments:
Total investments	677,954	230,415
Level 2 [Member] | Investments [Member] | US treasury bills [Member]
Investments:
Total investments	469,386	33,026
Level 2 [Member] | Investments [Member] | US agency securities [Member]
Investments:
Total investments	208,568	197,389
Level 3 [Member]
Liabilities
Contingent Milestone Payments	45,258
Total liabilities	45,258
Cash equivalents [Member] | Money market funds [Member]
Cash equivalents:
Assets, fair value	251,891	447,146
Cash equivalents [Member] | Level 1 [Member] | Money market funds [Member]
Cash equivalents:
Assets, fair value	$ 251,891	$ 447,146

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - ZebiAI Therapeutics, Inc. [Member] - Level 3 [Member] $ in Millions	Apr. 22, 2021USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Business combination contingent consideration liability, milestones payments	$ 85
Business combination contingent consideration liability, contingent earnout payments	$ 100

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Changes in Fair Value of Contingent Consideration Liability (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning balance	$ 0
Contingent Milestone Payments related to acquisition of ZebiAI	42,422
Contingent Earnout Payments related to acquisition of ZebiAI	5,000
Increase in fair value of Contingent Milestone Payments	2,836
Ending balance	$ 50,258

Investments - Summary of Fair V

Investments - Summary of Fair Value of Available-for-Sale Investments by Type of Security (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	$ 679,042	$ 230,351
Unrealized Losses	(1,088)
Unrealized Gains		64
Fair Value	677,954	230,415
Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	298,301	50,993
Unrealized Losses	(366)
Unrealized Gains		26
Fair Value	297,935	51,019
Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	380,741	179,358
Unrealized Losses	(722)
Unrealized Gains		38
Fair Value	380,019	179,396
U.S treasury bills [Member] | Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	189,406	29,997
Unrealized Losses	(228)
Unrealized Gains		21
Fair Value	189,178	30,018
U.S treasury bills [Member] | Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	280,743	3,008
Unrealized Losses	(535)
Fair Value	280,208	3,008
U.S agency securities [Member] | Investments with a maturity of one year or less [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	108,895	20,996
Unrealized Losses	(138)
Unrealized Gains		5
Fair Value	108,757	21,001
U.S agency securities [Member] | Investments with a maturity of one to two years [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	99,998	176,350
Unrealized Losses	(187)
Unrealized Gains		38
Fair Value	$ 99,811	$ 176,388

Investments - Additional Inform

Investments - Additional Information (Detail)	Dec. 31, 2021USD ($)DebtSecurity	Dec. 31, 2020USD ($)DebtSecurity
Investments [Abstract]
Debt securities unrealized loss position | DebtSecurity	88	9
Aggregate fair value of debt securities in unrealized loss position	$ 667,000,000	$ 70,500,000
Debt securities in continuous unrealized loss position for more than 12 months	$ 0	$ 0

Acquisition of ZebiAI - Additio

Acquisition of ZebiAI - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Apr. 22, 2021	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Fair value of contingent milestone payments and earnout payments		$ 50,258	$ 0
ZebiAI Therapeutics, Inc. [Member]
Business Acquisition [Line Items]
Acquisition date	Apr. 22, 2021
Upfront consideration payable	$ 20,000
Aggregate fair value consideration transferred	61,800
Milestone payments	$ 85,000
Percentage of payment related to collaboration or other agreements	10.00%
Payment related to collaboration or other agreements	$ 100,000
Consideration transferred	135,500
Loss on initial consolidation of VIE	$ 11,855
Stock-based compensation expense associated with accelerated vesting for certain stock options		4,600
Fair value of contingent milestone payments and earnout payments		$ 45,300
Number of shares that would be issued upon milestone achievement		2,817,555
Average share value of 5-day		$ 30.17
Contingent consideration payment description		The Contingent Milestone Payments are payable in common shares based on a fixed amount assigned to each milestone and the weighted average share price of the Company’s stock for the 5-day period prior to the milestone achievement.
ZebiAI Therapeutics, Inc. [Member] | General And Administrative Expense [Member]
Business Acquisition [Line Items]
Acquisition-related costs		$ 900
ZebiAI Therapeutics, Inc. [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Issued shares of common stock	1,914,219
ZebiAI Therapeutics, Inc. [Member] | Milestone Payments [Member]
Business Acquisition [Line Items]
Fair value of contingent milestone payments and earnout payments	$ 42,400
ZebiAI Therapeutics, Inc. [Member] | Earnout Payments [Member]
Business Acquisition [Line Items]
Fair value of contingent milestone payments and earnout payments	$ 5,000

Acquisition of ZebiAI - Summary

Acquisition of ZebiAI - Summary of Net Assets Acquired Based on Estimated Fair Values (Detail) - ZebiAI Therapeutics, Inc. [Member] $ in Thousands	Apr. 22, 2021USD ($)
Business Acquisition [Line Items]
Acquired IPR&D asset	$ 123,000
Loss on initial consolidation of VIE	11,855
Assets obtained in asset acquisition	662
Liabilities assumed in asset acquisition	(2,330)
Intangible asset	2,300
Net acquired assets	$ 135,487

Collaboration and License Arr_2

Collaboration and License Arrangements - Additional Information (Detail) - USD ($)	May 13, 2021	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Collaboration And License Arrangement [Line Items]
Collaboration revenue				$ 3,029,000	$ 82,654,000
Contract asset		$ 4,537,000		4,537,000	7,654,000
Other liabilities		15,000,000		$ 15,000,000
EQRx, Inc [Member]
Collaboration And License Arrangement [Line Items]
Collaborative arrangement, purpose				In August 2021, the Company and EQRx, Inc. (“EQRx”) entered into the Discovery Collaboration Agreement (“Collaboration Agreement”) to discover, develop, and commercialize novel medicines against validated oncology targets.
Collaborative arrangement, rights and obligations				Under the terms of the Collaboration Agreement, the Company is responsible for the discovery collaboration phase through to filing of the application for an Investigational New Drug (“IND”), while EQRx is responsible for clinical development, regulatory and commercialization of the product candidates under the collaboration. Subject to certain opt-out rights, the Company and EQRx share equally in the discovery, development and commercialization costs, as well as the net profits and losses from sales of any collaboration medicines, if approved. The Company retains the right to develop any collaboration medicines in combination with its wholly-owned pipeline.
Genentech [Member] | Genentech Agreement [Member]
Collaboration And License Arrangement [Line Items]
Collaborative arrangement, purpose				On December 11, 2020, the Company entered into the Genentech Agreement, which granted Genentech a license to develop and commercialize RLY-1971.
Collaborative arrangement, rights and obligations				RLY-1971 is currently being developed in a Phase 1a clinical trial for patients with advanced solid tumors (the “Phase 1a Trial”). Unless Genentech elects to exercise its option to conduct the remainder of the ongoing Phase 1a Trial, the Company is responsible for the completion of this trial. Genentech is responsible for conducting all subsequent clinical development of RLY-1971. The Company is also responsible for the one-time transfer of the active pharmaceutical ingredient (“API”) and other materials related to RLY-1971 to Genentech.
Non-refundable upfront payment				$ 75,000,000
Milestone payment receivable				5,000,000
Maximum additional amount received upon milestone achievement				695,000,000
Collaboration agreement transaction price				86,500,000
Non-refundable milestone payment transfer amount	$ 5,000,000			5,000,000
Non-refundable milestone payment for completion amount				5,000,000
Variable consideration related to reimbursements due for research and development services				1,500,000
Development based milestone payments under agreement				0
Regulatory based milestone payments under agreement				0
Collaboration revenue				2,600,000	82,700,000
Milestone payment received		15,000,000
Other liabilities		15,000,000		15,000,000
Genentech [Member] | Genentech Agreement [Member] | Research and Development Services [Member]
Collaboration And License Arrangement [Line Items]
Collaboration revenue				1,700,000	0
Genentech [Member] | Genentech Agreement [Member] | Transfer of Active Pharmaceutical Ingredients [Member]
Collaboration And License Arrangement [Line Items]
Collaboration revenue			$ 300,000		$ 0
Contract asset		4,500,000		4,500,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member]
Collaboration And License Arrangement [Line Items]
Collaboration agreement transaction price				86,500,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Transfer of License [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		83,300,000		83,300,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Research and Development Services [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		2,900,000		2,900,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Transfer of Active Pharmaceutical Ingredients [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		$ 300,000		300,000
Genentech [Member] | Genentech Agreement [Member] | Outside US [Member]
Collaboration And License Arrangement [Line Items]
Maximum additional amount received upon milestone achievement				$ 410,000,000

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant and Equipment [Line Items]
Property and equipment	$ 20,910	$ 16,780
Less: accumulated depreciation	(14,367)	(10,530)
Total property and equipment, net	6,543	6,250
Laboratory Equipment [Member]
Property Plant and Equipment [Line Items]
Property and equipment	15,797	13,534
Leasehold Improvements [Member]
Property Plant and Equipment [Line Items]
Property and equipment	2,897	886
Computer Equipment [Member]
Property Plant and Equipment [Line Items]
Property and equipment	1,093	888
Furniture and Fixtures [Member]
Property Plant and Equipment [Line Items]
Property and equipment	989	895
Construction in Process [Member]
Property Plant and Equipment [Line Items]
Property and equipment	$ 134	$ 577

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 3,925	$ 3,549	$ 2,845

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
External research and development	$ 10,755	$ 5,099
Professional services	2,613	464
Other	585	197
Total accrued expenses and other current liabilities	$ 13,953	$ 5,760

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Oct. 31, 2021	Aug. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Voting Rights			Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders.
Dividends declared			$ 0
Common Stock Restriction Period			4 years
Net proceeds			$ 4,739,000	$ 1,216,000	$ 613,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares sold	15,188,679		15,188,679	23,000,000
Additional shares issued	1,981,132
Offering price per share	$ 26.50
Net proceeds	$ 382,200,000
Common Stock [Member] | Sales Agreement [Member] | Cowen [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate gross proceeds from the sale of shares		$ 300,000,000
Common stock shares sold			0
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares, vested			$ 3,400,000
Maximum [Member] | Sales Agreement [Member] | Cowen [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of commission of shares sold		3.00%

Common Stock - Summary Of The R

Common Stock - Summary Of The Restricted Stock Activity (Detail) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares - Beginning | shares	84,489
Shares - Vested | shares	(84,489)
Weighted- Average Purchase Price - Beginning | $ / shares	$ 0.04
Weighted- Average Purchase Price - Vested | $ / shares	$ 0.04

Stock Compensation - Additional

Stock Compensation - Additional Information (Detail) - USD ($)	Jan. 01, 2021	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Aug. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense			$ 48,454,000	$ 31,960,000	$ 4,456,000
Time-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value			$ 32,400,000	$ 2,400,000
Weighted average grant date fair value of stock option granted			$ 22.95	$ 14.77	$ 3.35
Total unrecognized compensation cost related to the unvested stock-based awards, Value		$ 53,600,000	$ 53,600,000
Total unrecognized compensation cost related to the unvested stock-based awards, Weighted average period			1 year 8 months 12 days
Performance-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value			$ 1,100,000
Weighted average grant date fair value of stock option granted			$ 20.28	$ 37.48
Total unrecognized compensation cost related to the unvested stock-based awards, Value		21,400,000	$ 21,400,000
Total unrecognized compensation cost related to the unvested stock-based awards, Weighted average period			1 year 1 month 6 days
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares, vested			$ 2,600,000
Total unrecognized compensation cost related to the unvested stock-based awards, Value		$ 22,300,000	$ 22,300,000
Total unrecognized compensation cost related to the unvested stock-based awards, Weighted average period			1 year 9 months 18 days
2016 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized						0
2020 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized		9,735,928	9,735,928	8,376,080
Percentage of additional common stock authorized	5.00%
Increase in number of shares of common stock available for issuance	4,495,341
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized		1,947,915	1,947,915	1,092,532
Percentage of additional common stock authorized				1.00%
Increase in number of shares of common stock available for issuance	899,068
Total share-based compensation expense		$ 600,000
Percentage of fair market value of common stock				85.00%
Shares authorized additionally under ESPP	2,185,064
Total unrecognized compensation cost related to the unvested stock-based awards, Value		0	$ 0
Amount withheld from employees, on an after-tax basis		$ 1,200,000
Purchase of common stock		43,685

Stock Compensation - Schedule o

Stock Compensation - Schedule of Total Stock-based Compensation Expense Recognized (Detail) - 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]
Total share-based compensation expense	$ 48,454	$ 31,960	$ 4,456
Research and development expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	24,922	14,691	2,687
General and administrative expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 23,532	$ 17,269	$ 1,769

Stock Compensation - Schedule_2

Stock Compensation - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Time-Based Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and Warrants Outstanding, Number of Shares Beginning Balance	5,756,578
Granted, Number of Shares	2,363,676
Exercised, Number of Shares	(960,768)
Cancelled, Number of Shares	(253,119)
Options and Warrants Outstanding, Number of Shares Ending Balance	6,906,367	5,756,578
Shares, Vested	2,971,597
Shares, Unvested	3,934,770
Weighted Average Exercise Price Per Share, Outstanding Beginning Balance	$ 7.59
Weighted Average Exercise Price Per Share, Granted	34.20
Weighted Average Exercise Price Per Share, Exercised	4.82
Weighted Average Exercise Price Per Share, Cancelled	15.37
Weighted Average Exercise Price Per Share, Outstanding Ending Balance	16.80	$ 7.59
Weighted Average Exercise Price Per Share, Vested	8.24
Weighted Average Exercise Price Per Share, Unvested	$ 23.27
Weighted Average Remaining Contractual Life, Outstanding	7 years 10 months 24 days	7 years 7 months 17 days
Weighted Average Remaining Contractual Life, Vested	7 years 1 month 2 days
Weighted Average Remaining Contractual Life, Unvested	8 years 6 months 3 days
Aggregate Intrinsic Value, Outstanding Value	$ 111,021	$ 196,634
Aggregate Intrinsic Value, Vested Value	68,991
Aggregate Intrinsic Value, Unvested Value	$ 42,029
Performance-Based Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and Warrants Outstanding, Number of Shares Beginning Balance	1,940,480
Granted, Number of Shares	12,073
Exercised, Number of Shares	(35,768)
Cancelled, Number of Shares	(103,525)
Options and Warrants Outstanding, Number of Shares Ending Balance	1,813,260	1,940,480
Shares, Vested	499,464
Shares, Unvested	1,313,796
Weighted Average Exercise Price Per Share, Outstanding Beginning Balance	$ 5.22
Weighted Average Exercise Price Per Share, Granted	33.39
Weighted Average Exercise Price Per Share, Exercised	5.22
Weighted Average Exercise Price Per Share, Cancelled	5.22
Weighted Average Exercise Price Per Share, Outstanding Ending Balance	5.41	$ 5.22
Weighted Average Exercise Price Per Share, Vested	5.22
Weighted Average Exercise Price Per Share, Unvested	$ 5.48
Weighted Average Remaining Contractual Life, Outstanding	8 years 1 month 9 days	8 years 6 months 29 days
Weighted Average Remaining Contractual Life, Vested	8 years 10 days
Weighted Average Remaining Contractual Life, Unvested	8 years 1 month 20 days
Aggregate Intrinsic Value, Outstanding Value	$ 45,912	$ 70,517
Aggregate Intrinsic Value, Vested Value	12,731
Aggregate Intrinsic Value, Unvested Value	$ 33,181

Stock Compensation - Schedule_3

Stock Compensation - Schedule of Estimated Fair Value of Stock Options (Detail) - Time-Based Stock Options [Member]	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate minimum	0.60%	0.40%	1.54%
Risk-free interest rate maximum	1.60%	1.80%	2.50%
Expected term (in years)	6 years 3 months 18 days	6 years 3 months	6 years 3 months 18 days
Expected volatility rate minimum	74.70%	73.50%	72.80%
Expected volatility rate maximum	76.60%	77.60%	73.50%
Expected dividend yield	0.00%	0.00%	0.00%

Stock Compensation - Schedule_4

Stock Compensation - Schedule of Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Underlying RSUs, Granted | shares	782,299
Number of Shares Underlying RSUs, Vested | shares	(75,875)
Number of Shares Underlying RSUs, Cancelled | shares	(15,219)
Shares - Ending | shares	691,205
Weighted Average Grant Date Fair Value, Granted | $ / shares	$ 33.39
Weighted Average Grant Date Fair Value, Vested | $ / shares	34.54
Weighted Average Grant Date Fair Value, Cancelled | $ / shares	37.63
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 34.51

Stock Compensation - Schedule_5

Stock Compensation - Schedule of Estimated Fair Value of Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.10%
Expected term (in years)	6 months
Expected volatility	65.10%
Expected dividend yield	0.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Income tax benefits	$ 0	$ 0
Net operating loss carryforwards, federal	371,400,000	174,000,000
Net operating loss carryforwards, state	466,200,000	192,300,000
Increase in valuation allowance	76,900,000	14,300,000
Unrecognized tax benefits	$ 0	0
Description of income tax examinations	There are currently no pending tax examinations.
Tax Cuts and Jobs Act of 2017, description of corporate tax payers	Corporate taxpayers may carryback NOLs originating during 2018 through 2020 for up to five years, which was not previously allowed under the 2017 Tax Act. The CARES Act also eliminates the 80% of taxable income limitations by allowing corporate entities to fully utilize NOL carryforwards to offset taxable income in 2018, 2019 or 2020. Taxpayers may generally deduct interest up to the sum of 50% of adjusted taxable income plus business interest income (30% limit under the 2017 Tax Act) for tax years beginning January 1, 2019 and 2020. The CARES Act allows taxpayers with alternative minimum tax credits to claim a refund in 2020 for the entire amount of the credits instead of recovering the credits through refunds over a period of years, as originally enacted by the 2017 Tax Act.
CARES Act, percentage of eliminates of taxable income	80.00%
Tax Cuts and Jobs Act of 2017, maximum percentage of interest deducted by tax payers	50.00%
CARES Act, percentage of interest deducted by tax payers	30.00%
CARES Act, percentage of corporate charitable deduction limit	25.00%
CARES Act, period of qualified improvement property for cost-recovery	15 years
CARES Act, percentage of bonus depreciation	100.00%
Maximum [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryback period	5 years
Federal [Member]
Income Tax Disclosure [Line Items]
Income tax benefits	$ 0
Net operating loss carryforwards, subject to expiration	43,100,000
Net operating loss carryforwards, not subject to expiration	$ 328,300,000
Net operating loss carryforwards, beginning to expiring year	2035
Research and development tax credit carryforwards	$ 14,900,000	8,100,000
Research and development tax credit carryforwards, expiration year	2035
State [Member]
Income Tax Disclosure [Line Items]
Income tax benefits	$ 0
Net operating loss carryforwards, beginning to expiring year	2035
Research and development tax credit carryforwards	$ 4,200,000	$ 2,700,000
Research and development tax credit carryforwards, expiration year	2030

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income tax computed at federal statutory rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	5.70%	5.70%	7.00%
Change in valuation allowance	(20.50%)	(27.30%)	(31.00%)
IPR&D	(7.00%)
R&D credit carryovers	2.20%	7.60%	4.10%
Stock-based compensation	(0.40%)	(6.70%)	(0.90%)
Permanent differences	(1.00%)	(0.30%)	(0.20%)
Total	0.00%	0.00%	0.00%

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating losses	$ 108,800	$ 48,832
Tax credit carryforwards	18,288	10,270
Lease liability	6,010	6,430
Intangibles	1,859	1,469
Stock-based compensation	8,374	4,496
Depreciation and amortization	477	230
Other	4,304	14
Total gross deferred tax asset	148,112	71,741
Valuation allowance	(142,674)	(65,813)
Net deferred tax asset	5,438	5,928
Deferred tax liability
Operating lease assets	5,438	(5,928)
Total deferred tax liability	$ (5,438)	$ (5,928)

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (363,872)	$ (52,412)	$ (75,305)
Deemed dividend resulting from extinguishment upon modification of Series C preferred stock		(177,789)
Net loss attributable to common stockholders	$ (363,872)	$ (230,201)	$ (75,305)
Net loss attributable to common stockholders per share, basic and diluted	$ (3.82)	$ (5.40)	$ (21.82)
Weighted average shares of common stock, basic and diluted	95,136,719	42,619,582	3,450,500

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Detail) - $ / shares	Jul. 08, 2020	Jul. 07, 2020
Series C Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Preferred Stock Convertible Conversion Price	$ 3.027603	$ 3.21

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Antidilutive Securities Excluded From Computation of Earnings Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	9,410,832	7,781,547	65,869,211
Convertible preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			59,883,877
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	8,719,627	7,697,058	5,306,176
Unvested restricted stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		84,489	679,158
Unvested restricted stock units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	691,205

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jun. 15, 2020USD ($)	Dec. 31, 2021USD ($)Targetshares	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)shares
Commitments and Contingencies Disclosure [Line Items]
Accrued expenses		$ 13,953,000	$ 5,760,000
DE Shaw Research [Member]
Commitments and Contingencies Disclosure [Line Items]
Research and development expense		9,500,000	6,400,000	$ 1,500,000
Prepaid expense		$ 4,400,000
Accrued expenses			1,500,000
DE Shaw Research [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Outstanding convertible preferred stock converted into common shares | shares		3,281,253
Research and development arrangement, annual fee	$ 9,900,000			1,000,000
Research and development arrangement, term of contract		3 years
Research and development arrangement, expiration date	Aug. 16, 2025
Milestone payment Due		$ 7,300,000
Maximum additional amount received upon milestone achievement		6,300,000
DE Shaw Research [Member] | Lease Agreement
Commitments and Contingencies Disclosure [Line Items]
Milestone payment Due		0	1,500,000
Other Third Parties [Member]
Commitments and Contingencies Disclosure [Line Items]
Research and development expense		5,400,000	2,700,000	$ 3,500,000
Other Third Parties [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Milestone payment Due		$ 500,000	$ 0
Number of milestone targets | Target		4
Series A Preferred Stock [Member] | DE Shaw Research [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Shares held | shares				9,999,999
Series C Preferred Stock [Member] | DE Shaw Research [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Shares held | shares				1,557,875
Maximum [Member] | DE Shaw Research [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Agreement renewal period		1 year
Potential development milestone payments		$ 7,300,000
Maximum [Member] | Other Third Parties [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Potential development milestone payments		7,000,000
Minimum [Member] | Other Third Parties [Member] | License Agreement Terms [Member]
Commitments and Contingencies Disclosure [Line Items]
Potential development milestone payments		$ 4,000,000

Leases - Additional Information

Leases - Additional Information (Details)	May 26, 2021USD ($)ft²	Sep. 30, 2020ft²	Dec. 31, 2017ft²	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2021USD ($)	Jan. 31, 2018ft²
Operating Leased Assets [Line Items]
Operating lease option to terminate				true
Right of use asset				$ 20,780,000	$ 22,579,000
BMR Hampshire, LLC [Member]
Operating Leased Assets [Line Items]
Letter of credit				$ 1,700,000
Letter of credit expiration date				Aug. 31, 2033
Area of Land | ft²	41,474
Fixed lease payments				$ 55,700,000
Contribution toward the cost of construction and tenant improvements for the premises	$ 6,200,000
Term of the lease				10 years
Right of use asset							$ 0
399 Binney Street [Member]
Operating Leased Assets [Line Items]
Operating lease agreement expiration date		2029-04	2029-04
Land subject to ground leases | ft²		1,824	44,336					44,807
Letter of credit				$ 900,000
Letter of credit expiration date				Sep. 30, 2028
Fixed lease payments				$ 5,400,000	4,900,000	$ 2,600,000
Right of use asset				$ 20,780,000	$ 22,579,000
Weighted-average remaining lease term				7 years 3 months 18 days	8 years 3 months 18 days
Weighted-average discount rate				10.40%	10.40%

Leases - Schedule of Operating

Leases - Schedule of Operating Leases Presentation in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Leased Assets [Line Items]
Operating lease assets	$ 20,780	$ 22,579
Current operating lease liabilities	1,844	1,521
Non-current operating lease liabilities	21,056	22,901
399 Binney Street [Member]
Operating Leased Assets [Line Items]
Operating lease assets	$ 20,780	$ 22,579
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Operating lease assets	Operating lease assets
Current operating lease liabilities	$ 1,844	$ 1,521
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current operating lease liabilities	Current operating lease liabilities
Non-current operating lease liabilities	$ 21,056	$ 22,901
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Non-current operating lease liabilities	Non-current operating lease liabilities
Total lease liabilities	$ 22,900	$ 24,422

Leases - Summary of Operating L

Leases - Summary of Operating Lease Presentation in Consolidated Statements of Operations and Comprehensive Loss (Details) - 399 Binney Street [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Leased Assets [Line Items]
Operating lease costs	$ 4,108	$ 4,021	$ 3,797
Research and development expenses [Member]
Operating Leased Assets [Line Items]
Operating lease costs	3,262	3,273	3,216
General and administrative expenses [Member]
Operating Leased Assets [Line Items]
Operating lease costs	$ 846	$ 748	$ 581

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments (Details) - 399 Binney Street [Member] - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Leased Assets [Line Items]
2022	$ 4,134
2023	4,254
2024	4,377
2025	4,503
2026	4,634
Thereafter	11,325
Total lease payments	33,227
Less: interest	(10,327)
Present value of operating lease liabilities	$ 22,900	$ 24,422

Employee Benefits - Additional

Employee Benefits - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)
Compensation And Retirement Disclosure [Abstract]
Employer matching contribution	$ 1.2