0001628280-22-021950 | 10-K/A | XBRL Viewer

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Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2021	Feb. 25, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K/A
Document Annual Report	true
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	001-39634
Entity Registrant Name	Foghorn Therapeutics Inc.
Entity Incorporation, State	DE
Entity Tax Identification Number	47-5271393
Entity Address, Street	500 Technology Square, Ste 700
Entity Address, City	Cambridge
Entity Address, State	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	586-3100
Title of each class	Common Stock, $0.0001 Par Value
Trading Symbol(s)	FHTX
Name of each exchange on which registered	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 208.8
Entity Common Stock, Shares Outstanding		41,421,964
Amendment Flag	true
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0001822462
Amendment Description	EXPLANATORY NOTEFoghorn Therapeutics Inc. (the “Company”) is filing this Amendment No. 1 (this “Amendment”) on Form 10-K/A to amend its Annual Report on Form 10-K for the year ended December 31, 2021, filed with the Securities and Exchange Commission on March 10, 2022 (the “Original 10-K”), solely for the purpose of filing revised versions of Exhibits 31.1, 31.2, 32.1 and 32.2 (the “Revised Certifications”) filed with the Original 10-K.The Company is filing revised Exhibits 31.1 and 31.2 solely in order to include in the certifications set forth in the exhibits the language added to the introductory portion of paragraph 4 and the language of revised paragraph 4(b), which language was inadvertently omitted from the certifications when originally filed. The Company is filing revised Exhibits 32.1 and 32.2 solely in order to reflect that the period of certification referred to is the year ended December 31, 2021.This Amendment does not reflect events occurring after the date of the filing of the Original 10-K or modify or update any of the other disclosures contained therein in any way. Accordingly, this Amendment should be read in conjunction with the Original 10-K. This Amendment consists of the original report on Form 10-K as previously filed, omitting exhibits not related to the Revised Certifications, along with this Explanatory Note succeeding the cover page, the signature page, an updated Exhibit 23.1 consent of the Company's independent registered public accounting firm and the Revised Certifications.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2021
Audit Information [Abstract]
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 101,136	$ 92,795
Marketable securities	53,153	92,975
Collaboration receivable	300,000	0
Prepaid expenses and other current assets	5,273	4,917
Total current assets	459,562	190,687
Property and equipment, net	17,563	19,528
Restricted cash	1,733	1,733
Other assets	2,400	842
Operating lease right-of-use assets	38,516	42,804
Total assets	519,774	255,594
Current liabilities:
Accounts payable	3,819	3,680
Accrued expenses and other current liabilities	9,562	9,161
Operating lease liabilities	6,994	3,981
Deferred revenue	28,317	2,024
Total current liabilities	48,692	18,846
Notes payable, net of discount	0	19,654
Operating lease liabilities, net of current portion	51,338	58,361
Deferred revenue, net of current portion	322,730	12,546
Other liabilities	143	0
Total liabilities	422,903	109,407
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 25,000,000 shares authorized as of December 31, 2021 and 2020; no shares issued or outstanding	0	0
Common stock, $0.0001 par value; 175,000,000 shares authorized at December 31, 2021 and 2020; 41,299,720 shares issued and outstanding at December 31, 2021 and 36,790,946 shares issued and outstanding at December 31, 2020	4	4
Additional paid-in capital	361,133	309,126
Accumulated other comprehensive loss	(10)	(7)
Accumulated deficit	(264,256)	(162,936)
Total stockholders’ equity	96,871	146,187
Total liabilities and stockholders’ equity	$ 519,774	$ 255,594

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares, issued (in shares)	0	0
Proferred stock, shares, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	175,000,000	175,000,000
Common stock, shares, issued (in shares)	41,299,720	36,790,946
Common stock, shares, outstanding (in shares)	41,299,720	36,790,946

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Collaboration revenue	$ 1,319	$ 430
Operating expenses:
Research and development	80,325	57,715
General and administrative	21,728	11,246
Total operating expenses	102,053	68,961
Loss from operations	(100,734)	(68,531)
Other income (expense):
Interest expense	(1,906)	(979)
Interest income and other income (expense), net	2,553	1,001
Change in fair value of preferred stock warrant liability	0	(69)
Loss on debt extinguishment	(1,233)	(222)
Total other expense, net	(586)	(269)
Net loss	$ (101,320)	$ (68,800)
Net loss per share attributable to common stockholders—basic (in dollars per share)	$ (2.73)	$ (6.23)
Net loss per share attributable to common stockholders—diluted (in dollars per share)	$ (2.73)	$ (6.23)
Weighted average common shares outstanding—basic (in shares)	37,171,147	11,046,802
Weighted average common shares outstanding—diluted (in shares)	37,171,147	11,046,802
Comprehensive loss:
Net loss	$ (101,320)	$ (68,800)
Other comprehensive loss:
Unrealized losses on marketable securities	(3)	(7)
Total other comprehensive loss	(3)	(7)
Total comprehensive loss	$ (101,323)	$ (68,807)

Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity - USD ($) $ in Thousands	Total	IPO	Share Purchase Agreement	Common Stock	Common Stock IPO	Common Stock Share Purchase Agreement	Additional Paid-in Capital	Additional Paid-in Capital IPO	Additional Paid-in Capital Share Purchase Agreement	Accumulated Other Comprehensive Loss	Accumulated Deficit	Series A-1, A-2 and B Convertible Preferred Stock	Series A-1, A-2 and B Convertible Preferred Stock Preferred Stock
Beginning balance at Dec. 31, 2019													$ 86,544
Beginning balance (in shares) at Dec. 31, 2019													28,615,546
Increase (Decrease) in Temporary Equity
Issuance of Series B convertible preferred stock, net of issuance costs												$ 89,861
Issuance of Series B convertible preferred stock, net of issuance costs (in shares)													12,007,867
Conversion of preferred stock to common stock												$ (176,405)
Conversion of preferred stock to common stock (in shares)													(40,623,413)
Ending balance at Dec. 31, 2020													$ 0
Ending balance (in shares) at Dec. 31, 2020													0
Beginning balance at Dec. 31, 2019	$ (88,016)			$ 0			$ 6,120				$ (94,136)
Beginning balance (in shares) at Dec. 31, 2019				4,870,851
Increase (Decrease) in Stockholders' Equity
Conversion of preferred stock to common stock	176,405			$ 3			176,402
Conversion of preferred stock to common stock (in shares)				21,958,588
Issuance of stock during the period new shares issued		$ 122,121			$ 1			$ 122,120
Stock issued during the period shares new issues shares (in shares)					8,451,837
Conversion of warrant liability to equity upon closing of initial public offering	114						114
Issuance of common stock in connection with the cashless exercise of warrants				6,728
Issuance of common stock upon exercise of stock options	1,221						1,221
Issuance of common stock upon exercise of stock options (in shares)				611,048
Issuance of warrants in connection with notes payable	188						188
Vesting of restricted stock (in shares)				891,894
Stock-based compensation expense	2,961						2,961
Unrealized losses on marketable securities	(7)									$ (7)
Net loss	(68,800)										(68,800)
Ending balance at Dec. 31, 2020	$ 146,187			$ 4			309,126			(7)	(162,936)
Ending balance (in shares) at Dec. 31, 2020	36,790,946			36,790,946
Ending balance at Dec. 31, 2021													$ 0
Ending balance (in shares) at Dec. 31, 2021													0
Increase (Decrease) in Stockholders' Equity
Issuance of stock during the period new shares issued			$ 42,205						$ 42,205
Stock issued during the period shares new issues shares (in shares)						4,000,000
Issuance of common stock upon exercise of stock options	$ 1,418						1,418
Issuance of common stock upon exercise of stock options (in shares)	508,774			508,774
Stock-based compensation expense	$ 8,384						8,384
Unrealized losses on marketable securities	(3)									(3)
Net loss	(101,320)										(101,320)
Ending balance at Dec. 31, 2021	$ 96,871			$ 4			$ 361,133			$ (10)	$ (264,256)
Ending balance (in shares) at Dec. 31, 2021	41,299,720			41,299,720

Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Series A-1, A-2 and B Convertible Preferred Stock \| Preferred Stock
Stock issuance costs	$ 198

Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
Consolidated Statements of Cash Flows $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Cash flows from operating activities:
Net loss	$ (101,320)	$ (68,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense related to issuance of options and employee stock purchase plan	8,384	2,961
Depreciation and amortization expense	3,227	1,327
Gain on disposal of property and equipment	0	(206)
Loss on debt extinguishment	1,233	222
Change in fair value of preferred stock warrant liability	0	69
Noncash lease expense	4,288	4,201
Noncash interest expense	318	238
Amortization (accretion) of premium/discount on marketable securities	179	(1)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,814)	(4,670)
Collaboration receivable	(300,000)	0
Accounts payable	135	474
Accrued expenses and other liabilities	2,653	3,194
Operating lease liabilities	(4,010)	15,135
Deferred revenue	336,477	14,570
Net cash used in operating activities	(50,250)	(31,286)
Cash flows from investing activities:
Purchases of property and equipment	(3,313)	(16,183)
Proceeds from sale of property and equipment	0	250
Purchases of marketable securities	(99,984)	(92,981)
Proceeds from maturities of marketable securities	139,470	0
Net cash provided by (used in) investing activities	36,173	(108,914)
Cash flows from financing activities:
Proceeds from stock purchase agreement	42,205	0
Proceeds from initial public offering, net of underwriting discounts, commissions and offering costs	0	122,121
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	89,861
Proceeds from issuance of common stock upon exercise of stock options	1,418	1,221
Proceeds from issuance of notes payable, net of issuance costs	0	19,800
Repayments of notes payable	(21,205)	(15,530)
Net cash provided by financing activities	22,418	217,473
Net increase in cash, cash equivalents and restricted cash	8,341	77,273
Cash, cash equivalents and restricted cash at beginning of period	94,528	17,255
Cash, cash equivalents and restricted cash at end of period	102,869	94,528
Supplemental cash flow information:
Cash paid for interest	1,716	660
Supplemental disclosure of noncash investing and financing information:
Purchases of property and equipment included in accounts payable, accrued expenses and other liabilities	295	2,400
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	101,136	92,795
Restricted cash (current and non-current)	1,733	1,733
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	102,869	94,528
Conversion of Redeemable Convertible stock
Supplemental disclosure of noncash investing and financing information:
Conversion of stock, amount converted	0	176,405
Conversion of Warrant Liability to Equity
Supplemental disclosure of noncash investing and financing information:
Conversion of stock, amount converted	0	114
Conversion of Notes Payable in to Warrants
Supplemental disclosure of noncash investing and financing information:
Issuance of warrants in connection with notes payable	$ 0	$ 188

Nature of Business and Basis of Presentation	12 Months Ended
Nature of Business and Basis of Presentation	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Nature of Business and Basis of Presentation Foghorn Therapeutics Inc. (the “Company”) is a clinical-stage biopharmaceutical company discovering and developing a new class of medicines targeting genetically determined dependencies within the chromatin regulatory system. The Company uses its proprietary Gene Traffic Control platform to identify, validate and potentially drug targets within the system. The Company was founded in October 2015 as a Delaware corporation. The Company is headquartered in Cambridge, Massachusetts. The Company is subject to risks similar to those of other early-stage companies in the biopharmaceutical industry, including dependence on key individuals, the need to develop commercially viable products, competition from other companies, many of whom are larger and better capitalized, the impact of the COVID-19 pandemic and the need to obtain adequate additional financing to fund the development of its products. 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 maintained, that any products developed will obtain required regulatory approval or that any approved products will be commercially viable. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from the sale of its products. In March 2020, the World Health Organization declared the global novel coronavirus disease 2019 (“COVID-19”) outbreak a pandemic. The Company’s operations have not been significantly impacted by the COVID-19 pandemic. However, the Company cannot at this time predict the specific extent, duration, or full impact that the COVID-19 pandemic will have on its financial condition and operations, including ongoing and planned clinical trials. The impact of the COVID-19 outbreak on the Company’s financial performance will depend on future developments, including the duration and spread of the pandemic and related governmental advisories and restrictions. These developments and the impact of COVID-19 on the financial markets and the overall economy are highly uncertain and cannot be predicted. If the financial markets and/or the overall economy are impacted for an extended period, the Company’s results may be materially adversely affected. On October 27, 2020, the Company completed its initial public offering (“IPO”) pursuant to which it issued and sold 7,500,000 shares of its common stock at a public offering price of $16.00 per share, resulting in net proceeds of $107.9 million, after deducting underwriting discounts and commissions and other offering expenses. On November 19, 2020, the Company issued and sold an additional 951,837 shares of common stock at the IPO price of $16.00 per share pursuant to the underwriters’ partial exercise of their option to purchase additional shares of common stock, resulting in additional net proceeds of $14.2 million after deducting underwriting discounts and commissions. On December 10, 2021, the Company executed a collaboration agreement with Eli Lilly and Company (or "Lilly") (See Note 9). Concurrent with the collaboration agreement the Company completed a stock purchase agreement (the "SPA") with Lilly and issued and sold Lilly 4,000,000 shares of its common stock at a price of $20.00 per share, resulting in net proceeds of $80.0 million of which $42.2 million was allocated to equity upon the issuance of the Company’s common stock (see Note 9). The accompanying consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has funded its operations primarily with proceeds from sales of preferred stock, debt financing, an upfront payment of $15.0 million the Company received in July 2020 under a collaboration agreement with Merck Sharp & Dohme Corp. (see Note 9), proceeds from the sale of common stock in the IPO completed in October 2020 and most recently, with sale of common stock in the SPA. In January 2022, the Company received an upfront payment of $300.0 million pursuant to the collaboration agreement with Lilly (See Note 9), which was included in current assets on the consolidated balance sheets as of December 31, 2021. The Company has incurred recurring losses, including net losses of $101.3 million and $68.8 million for the years ended December 31, 2021 and 2020, respectively. As of December 31, 2021, the Company had an accumulated deficit of $264.3 million. The Company expects to continue to generate operating losses in the foreseeable future. As of the issuance date of these consolidated financial statements the Company expects that its cash, cash equivalents and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months. The Company will need to obtain additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements to continue to fund its operations. 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 collaborative or strategic alliances or licensing arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. Arrangements with collaborators or others may require the Company to relinquish rights to certain of its technologies or programs. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs, pipeline expansion or commercialization efforts, which could adversely affect its business prospects. Although management will continue to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations when needed or at all. Basis of presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition and the accrual of research and development expenses. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates as there are changes in circumstances, facts and experience. Actual results may differ from those estimates or assumptions.

Concentrations of credit risk and of significant suppliers

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. As of December 31, 2021, the Company maintained cash, cash equivalents and marketable securities at financial institutions in excess of federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

The Company relies, and expects to continue to rely, on a small number of vendors to provide services, supplies and materials for certain activities related to its programs. These programs could be adversely affected by a significant interruption in these services or the availability of materials.

Cash equivalents

The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents.

Marketable Securities

The Company’s marketable securities are classified as available-for-sale and are carried at fair value with the unrealized gains and losses reported as a component of accumulated other comprehensive loss in stockholders’ equity. Realized gains and losses and declines in value judged to be other than temporary are included as a component of interest income and other income (expense), net based on the specific identification method. The Company classifies its marketable securities with maturities beyond one year as short-term, based on their highly liquid nature and because such marketable securities are available for current operations.

Restricted cash

Amounts included in restricted cash represent amounts pledged as collateral for letters of credit required for security deposits on the Company’s leased facilities and credit cards. These amounts are classified as restricted cash in the Company’s consolidated balance sheets.

Property and equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expense is recognized using the straight-line method over the estimated useful life of each asset as follows:


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment and software			3 years
Leasehold improvements			Shorter of useful life or remaining term of lease

Costs for capital assets not yet placed into service are depreciated once placed into service. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in loss from operations. Expenditures for repairs and maintenance are charged to expense as incurred.

Impairment of long-lived assets

The Company evaluates its long-lived assets, which consist primarily of property and equipment and operating lease right-of-use assets, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. The Company did not record any impairment losses on long-lived assets during the years ended December 31, 2021 or 2020.

Fair value measurements

Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•Level 1—Quoted prices in active markets for identical assets or liabilities.

•Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The Company’s cash equivalents and marketable securities are carried at fair value, determined according to the fair value hierarchy described above (see Note 3). The carrying values of the Company’s accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities. The carrying value of the Company’s long-term debt approximates its fair value (a level 2 measurement) due to its variable interest rate.

Collaboration Agreements

The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808, Collaborative Arrangements (ASC 808) to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. When the Company has concluded that it has a customer relationship with one of its collaborators the Company follows the guidance in ASC Topic 606, Revenue From Contracts With Customers (“ASC 606”).

Revenue recognition

The Company accounts for its two collaboration arrangements under ASC 606 as the Company concluded that it has a customer relationship with each of its collaborators. For additional information on the Company’s collaboration agreements, see Note 9, Collaboration Agreements, to these consolidated financial statements. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer.

The Company assesses the goods or services promised within each contract and determines those that are performance obligations. The promised goods or services in the Company’s arrangements would likely consist of licenses, rights to the Company’s intellectual property, research and development services and related supporting activities. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations.

The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). In assessing whether a promised good or service is distinct, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the customer and the availability of the associated expertise in the general marketplace. The Company also considers the intended benefit of the contract in assessing whether a promised good or service is separately identifiable from other promises in the contract. If a promised good or service is not distinct, an entity is required to combine that good or service with other promised goods or services until it identifies a bundle of goods or services that is distinct.

The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. Determining the SSP for performance obligations requires significant judgment. In developing the SSP for a performance obligation, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. The Company validates the SSP for performance obligations by evaluating whether changes in the key assumptions used to determine the SSP will have a significant effect on the allocation of arrangement consideration between multiple performance obligations.

If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment.

If an arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received.

For arrangements with licenses of intellectual property that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes royalty revenue and sales-based milestones at the later of (i) when the related sales occur, or (ii) when the performance obligation to which the royalty has been allocated has been satisfied.

The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded for deferred revenue.

In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between the transfer of the promised goods or services to the customer and the payment by the customer will be one year or less. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, either at a point in time or over time, and if over time, recognition is based on the use of an output or input method.

Research and development costs

Research and development expenses consist of costs incurred in performing research and development activities, including salaries and bonuses, stock-based compensation, employee benefits, facilities costs, laboratory supplies, depreciation, and external costs of vendors engaged to conduct research, preclinical and clinical development activities as well as the cost of licensing technology.

Upfront payments and milestone payments made for the licensing of technology are expensed as research and development over the period to which they relate. Costs for research and development activities are expensed in the period in which they are incurred. Payments for such activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the consolidated financial statements as prepaid expense or accrued research and development expense. Determining the prepaid and accrued balances at the end of any reporting period incorporate certain judgments and estimates by management that are based on information available to the Company including information provided by vendors regarding the progress to completion of specific tasks or costs incurred.

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.

Leases

In accordance with ASC 842, Leases, the Company accounts for a contract as a lease when it has the right to control the asset for a period of time while obtaining substantially all of the asset’s economic benefits. The Company determines if an arrangement is a lease or contains an embedded lease at inception. For arrangements that meet the definition of a lease, the Company determines the initial classification and measurement of its right-of-use asset and lease liability at the lease commencement date and thereafter if modified. The lease term includes any renewal options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its estimated secured incremental borrowing rate for that lease term. The Company’s policy is to not record leases with an original term of twelve months or less on its consolidated balance sheets and recognizes those lease payments in the income statement on a straight-line basis over the lease term. The Company’s existing leases are for office and laboratory space and an equipment lease.

In addition to rent, the leases may require the Company to pay additional costs, such as utilities, maintenance and other operating costs, which are generally referred to as non-lease components. The Company has elected to not separate lease and non-lease components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease component and recognized as part of a right-of-use asset and liability. Rent expense for operating leases is recognized on a straight-line basis over the reasonably assured lease term based on the total lease payments and is included in operating expense in the consolidated statements of operations and comprehensive loss.

Stock-based compensation

The Company measures stock options with service-based vesting or performance-based vesting granted to employees, non-employees and directors based on the fair value on the date of grant using the Black-Scholes option-pricing model. The Company measures restricted common stock awards using the difference between the purchase price per share of the award, if any, and the fair value of the Company’s common stock at the date of grant. Compensation expense for the awards is recognized over the requisite service period for employees and directors and as services are delivered for non-employees, both of which are generally the vesting period of the respective award. The Company uses the straight-line method to record the expense of awards with only service-based vesting conditions. The Company uses the graded-vesting method to record the expense of awards with both service-based and performance-based vesting conditions, commencing once achievement of the performance condition becomes probable. The Company accounts for forfeitures of share-based awards as they occur.

The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified.

Net loss per share

Basic net income (loss) per share attributable to common stockholders is computed by dividing net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share attributable to common stockholders is computed by dividing net income(loss) attributable to common stockholders by the weighted average number of common shares outstanding for the period, adjusted for potential dilutive common shares.

The Company’s participating securities contractually entitled the holders of such shares to participate in dividends but did not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reported a net loss, such losses were not allocated to such participating securities. In periods in which the Company reported a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

The Company reported a net loss attributable to common stockholders for the years ended December 31, 2021 and 2020.

The following common stock equivalents presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share because including them would have had an anti-dilutive impact:


	December 31,
	2021	2020
Stock options to purchase common stock	5,920,509	5,016,460
Warrants to purchase common stock	18,445	18,445
	5,938,954	5,034,905

Segments

Operating segments are defined as components of an entity for which separate discrete financial information is made available and that is regularly evaluated by the chief operating decision maker (“CODM”) in making decisions regarding resource allocation and assessing performance. The Company’s CODM is its chief executive officer and the Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company is focused on pioneering the discovery and development of a new class of medicines targeting genetically determined dependencies within the chromatin regulatory system.

Comprehensive loss

Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2021 and 2020, the Company’s only element of other comprehensive loss was unrealized losses on available for sale debt securities.

Income taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to the provision for income taxes. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. Any resulting unrecognized tax benefits are recorded within the provision for income taxes.

Recently issued accounting pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company can adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326). The new standard adjusts the accounting for assets held at amortized costs basis, including marketable securities accounted for as available for sale. The standard eliminates the probable initial recognition threshold and requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. For public entities, the guidance was effective for annual reporting periods beginning after December 15, 2019 and for interim periods within those fiscal years. For nonpublic entities and emerging growth companies that choose to take advantage of the extended transition period, the guidance is effective for annual reporting periods beginning after December 15, 2020. Early adoption is permitted for all entities. In November 2019, the FASB issued ASU No. 2019-10, which deferred the effective date for nonpublic entities to annual reporting periods beginning after December 15, 2022, including interim periods within those fiscal years. The Company is evaluating when to adopt this standard and the effect the adoption will have on its consolidated financial statements.

Marketable Securities and Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Marketable Securities and Fair Value Measurements

As of December 31, 2021, available for sale marketable securities by security type consisted of (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Commercial paper (due within one year)	$	36,246	$	—	$	(3)	$	36,243
Corporate notes and bonds (due within one year)	16,917		—		(7)		16,910
Total	$	53,163	$	—	$	(10)	$	53,153

As of December 31, 2020, available for sale marketable securities by security type consisted of (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury notes (due within one year)	$	92,982	$	—	$	(7)	$	92,975
Total	$	92,982	$	—	$	(7)	$	92,975

The following tables present the Company’s fair value hierarchy for its assets and liabilities, which were measured at fair value on a recurring basis (in thousands):


	Fair Value Measurements at December 31, 2021 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	82,252	$	—	$	—	$	82,252

Commercial paper	—		18,496		—		18,496
Marketable securities:
Commercial paper	—		36,243		—		36,243
Corporate notes and bonds	—		16,910		—		16,910
Total	$	82,252	$	71,649	$	—	$	153,901


	Fair Value Measurements at December 31, 2020 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	48,770	$	—	$	—	$	48,770
U.S. treasury notes	—		42,997		—		42,997
Marketable securities:
U.S. treasury notes	—		92,975		—		92,975
Total	$	48,770	$	135,972	$	—	$	184,742

During the years ended December 31, 2021 and 2020, there were no transfers between Level 1, Level 2 and Level 3.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2021		2020
Laboratory equipment	$	4,889	$	3,740
Furniture and fixtures	815		815
Computer equipment and software	100		100
Leasehold improvements	17,059		16,961
Assets not yet placed in service	30		15
	22,893		21,631
Less: Accumulated depreciation and amortization	(5,330)		(2,103)
	$	17,563	$	19,528

Depreciation and amortization expense was $3.2 million and $1.3 million for the years ended December 31, 2021 and 2020, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2021

Payables and Accruals [Abstract]

Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	December 31,
	2021		2020
Accrued employee compensation and benefits	$	5,596	$	3,513
Accrued tenant improvements	13		2,385
Accrued external research and development expenses	3,079		2,146
Accrued professional fees	495		979
Other	379		138
	$	9,562	$	9,161

Notes Payable

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Notes Payable

Long-term debt consisted of the following (in thousands):


	December 31,
	2021		2020
Principal amount of long-term debt	$	—	$	20,000
Less: Current portion of long-term debt	—		—
Long-term debt, net of current portion	—		20,000
Final payment fee	—		1,000
Debt discount, net of accretion	—		(1,346)
Long-term debt, net of discount and current portion	$	—	$	19,654

Loan and Security Agreements

On November 19, 2020, the Company entered into a loan and security agreement (the "Oxford Loan Agreement"), with Oxford Finance LLC, or Oxford, for an aggregate principal amount of $20.0 million (the "Oxford Term Loan A") and up to an additional $5.0 million (the "Oxford Term Loan B"). On November 19, 2020, the Company borrowed $20.0 million under the Oxford Term Loan A. Oxford Term Loan A and Oxford Term Loan B (the "Term Loans") bear interest at a floating per annum rate equal to the greater of (i) 8.0% and (ii) the sum of (a) thirty-day LIBOR rate plus (b) 7.84%. In addition, upon loan maturity or prepayment, the Company is required to make a final payment fee equal to 5.0% of the aggregate principal amount borrowed which is being amortized to interest expense over the term of the debt using the effective interest method.

The Company is required to make monthly interest only payments under the Oxford Loan each month beginning on January 1, 2021. Beginning on December 1, 2023, the Company is required to make consecutive equal monthly payments of principal, together with applicable interest, in arrears, based upon a repayment schedule equal to 24 months, with a final maturity date of November 1, 2025 (the “Maturity Date”). At the Company's option, the Company may elect to prepay the loans subject to a prepayment fee equal to the following percentage of the principal amount being prepaid: 2% if an advance is prepaid during the first 12 months following the applicable advance date, 1% if an advance is prepaid after 12 months but prior to 24 months following the applicable advance date, and 0.5% if an advance is prepaid any time after 24 months following the applicable advance date but prior to the Maturity Date.

In addition, in connection with the Oxford Loan Agreement, the Company granted warrants to purchase 18,445 shares of the Company’s common stock at $16.26 per share. The issued warrants are exercisable for 10 years. The Company valued the warrants using the Black-Scholes option pricing model and determined the fair value of the warrants to be $0.2 million. The Company determined the warrants met the criteria for equity classification, and, as such, the fair value of the warrants were recorded as additional paid-in capital upon issuance and as a discount to the debt which is being amortized to interest expense over the term of the Oxford Loan of five years. In addition, the Company incurred debt issuance costs of $0.2 million.

In December 2021, the Company repaid early the outstanding principal balance under the Term Loans as described above plus unpaid accrued interest, the final payment fee and the prepayment fee. The Company recorded a loss on debt extinguishment of $1.2 million related to this repayment for the year ended December 31, 2021.

During the years ended December 31, 2021 and 2020, the weighted average effective interest rate on outstanding borrowings was approximately 9.5% and 6.4%, respectively.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI http://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Section 50
-Paragraph 1C
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 1I
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1E
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Common Stock	12 Months Ended
Common Stock	Dec. 31, 2021
Equity [Abstract]
Common Stock	Common Stock On October 27, 2020, the Company completed its initial public offering (“IPO”) pursuant to which it issued and sold 7,500,000 shares of its common stock at a public offering price of $16.00 per share, resulting in net proceeds of $107.9 million, after deducting underwriting discounts and commissions and other offering expenses. On November 19, 2020, the Company issued and sold an additional 951,837 shares of common stock at the IPO price of $16.00 per share pursuant to the underwriters’ partial exercise of their option to purchase additional shares of common stock, resulting in additional net proceeds of $14.2 million after deducting underwriting discounts and commissions. Upon the closing of the IPO, all of the Company’s outstanding convertible preferred stock automatically converted into shares of common stock. On December 10, 2021, the Company completed a collaboration agreement with Lilly (See Note 9). Concurrent with the collaboration agreement the Company completed a stock purchase agreement with Lilly and issued and sold Lilly 4,000,000 shares of its common stock at a price of $20.00 per share, resulting in net proceeds of $80.0 million of which $42.2 million was allocated to equity upon the issuance of the Company’s common stock (see Note 9). 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 not entitled to receive dividends, unless declared by the board of directors.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

2016 Stock Incentive Plan

The Company’s 2016 Stock Incentive Plan, (the “2016 Plan”) provided for the Company to grant incentive stock options or nonqualified stock options and other equity awards to employees, directors and consultants of the Company. Upon the effectiveness of the 2020 Equity Incentive Plan (the “2020 Plan”) in October 2020, the Company ceased granting additional awards under the 2016 Plan.

2020 Equity Incentive Plan

The 2020 Plan provides for the grant of incentive stock options, non-qualified options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares initially reserved for issuance under the 2020 Plan was (i) 2,200,000 shares (the “share pool”), plus (ii) the number of shares of common stock available for issuance under the 2016 Plan as of the effective date of the 2020 Plan, plus the number of shares of common stock underlying awards under the 2016 Plan that on or after the date of adoption expire or become unexercisable without delivery of shares, are forfeited to, or repurchased for cash, are settled in cash, or otherwise become available again for grant under the 2016 Plan, in each case, in accordance with its terms (up to an aggregate of 5,078,295 shares). As of December 31, 2021, 2,271,847 shares remained available for future grant under the 2020 Plan.

The share pool will automatically increase on January 1 of each year from 2021 to 2030 by the lesser of (i) four percent of the number of shares of our common stock outstanding as of the close of business on the immediately preceding December 31 and (ii) the number of shares determined by the board of directors on or prior to such date for such year. The number of shares reserved for issuance under the 2020 Plan was increased by 1,651,989 shares effective January 1, 2022.

The 2020 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted with service-based vesting conditions generally vest over four years and expire after ten years. The exercise price for stock options granted is not less than the fair value of common stock on the date of grant. The Company bases fair value of common stock on the quoted market price. Prior to the IPO, the board of directors determined the value the Company’s common stock, taking into consideration its most recently available valuation of common stock performed by third parties as well as additional relevant factors which may have changed since the date of the most recent contemporaneous valuation through the date of grant.

2020 Employee Stock Purchase Plan

On October 21, 2020, the Company’s board of directors adopted and its stockholders approved the 2020 Employee Stock Purchase Plan (the “ESPP”), which became effective on October 21, 2020. The aggregate number of shares of common stock

available for purchase pursuant to the exercise of options under the ESPP is 360,000 shares, plus an automatic annual increase, as of January 1 of each year from 2021 to 2030, equal to the lesser of one percent of the number of shares of common stock outstanding as of the close of business on the immediately preceding December 31 and (ii) the number of shares determined by the board of directors on or prior to such date for such year (up to a maximum of 3,220,520 shares). The number of shares reserved for issuance under the ESPP was increased by 367,894 shares to 780,891 shares effective January 1, 2022.

The first offering period commenced under the ESPP on September 1, 2021. For the year ended December 31, 2021, the Company recognized a de minimis amount of expense related to the ESPP.

Stock option valuation

The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company currently lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.

The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted during the years ended December 31, 2021 and 2020 which was as follows:


	Year Ended December 31,
	2021		2020
Risk-free interest rate	0.7	%	0.4	%
Expected volatility	78.8	%	78.5	%
Expected dividend yield	—		—
Expected term (in years)	6.0		6.1

The following table summarizes the Company’s option activity during the year ended December 31, 2021 which was as follows:


	Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Outstanding as of December 31, 2020	5,016,460	$	4.93	8.5	$	76,941
Granted	1,719,563	15.41
Exercised	(508,774)	2.79
Forfeited	(306,740)	10.22
Outstanding as of December 31, 2021	5,920,509	$	7.88	7.9	$	88,720
Vested and expected to vest as of December 31, 2021	5,920,509	$	7.88	7.9	$	88,720
Options exercisable as of December 31, 2021	2,435,439	$	3.62	7.0	$	46,882

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2021 and 2020 was $5.3 million and $3.5 million, respectively.

The weighted average grant-date fair value of stock options granted during the years ended December 31, 2021 and 2020 was $10.40 per share and $6.01 per share, respectively.

Restricted common stock

During 2015, the Company issued and sold 4,459,459 shares of restricted common stock at par value to the scientific founders of the Company. The shares were subject to vesting over a period of five years and began vesting in April 2016 and were fully vested as of December 31, 2020.

The aggregate fair value of restricted stock that vested during the years ended December 31, 2020 was $4.8 million, respectively.

Stock-based compensation

The Company recorded stock-based compensation expense related to common stock options and restricted common stock in the following expense categories of its consolidated statements of operations and comprehensive loss during the years ended December 31, 2021 and 2020 which was as follows (in thousands):


	Year Ended December 31,
	2021		2020
Research and development expenses	$	4,324	$	1,724
General and administrative expenses	4,060		1,237
	$	8,384	$	2,961

As of December 31, 2021, total unrecognized compensation cost related to unvested options was $20.8 million, which is expected to be recognized over a weighted average period of 2.7 years.

Collaboration Agreements	12 Months Ended
Collaboration Agreements	Dec. 31, 2021
Collaboration Agreement [Abstract]
Collaboration Agreements	Collaboration Agreements Lilly Collaboration Agreement and Stock Purchase Agreement In December 2021, the Company entered into a collaboration agreement (the “Lilly Collaboration Agreement") with Lilly to create novel oncology medicines by applying Foghorn’s proprietary Gene Traffic Control platform. The collaboration includes a co-development and co-commercialization agreement for the Company’s selective BRM oncology target, consisting of two programs, and one additional undisclosed oncology target (collectively, the “Joint Programs”). The collaboration also includes three additional discovery targets or programs (collectively, the “Discovery Programs”) for a total of six programs directed at five targets. With respect to the Joint Programs, the Company will lead discovery and early research activities through the successful completion of dose finding toxicity studies for the identified compound, while Lilly will lead development and commercialization activities of the identified compound with participation from the Company in development activities and 50% cost sharing until registrational clinical trials. The Company and Lilly may jointly develop and commercialize the Joint Program compound though the Company may, in its sole discretion, opt-out on a program-by-program basis of further participation in the development and commercialization efforts prior to the first registrational clinical trial. If the Company does not opt-out, Lilly and the Company will continue to share in the costs to further develop and commercialize the Joint Program compound on a worldwide basis, equally share in the U.S. profits on product sales, subject to certain adjustments and receive royalties on sales outside of the United States (“Ex-U.S.”) at royalty rates ranging from low double digits to high twenties. If the Company opts-out of further development and commercialization efforts, it will have no further obligations to share in the development and commercialization costs, will receive royalties rather than profit share on U.S. sales and will receive royalties at a lower rate on Ex-U.S. sales. With respect to the Discovery Programs, the Company will lead discovery and early research activities through the successful completion of dose finding toxicity studies for the identified compounds. The Company may, in its sole discretion, opt in on a program-by-program basis after the successful completion of dose finding toxicity to participate in the further development and commercialization efforts of the Discovery Program compounds. If the Company opts-in to the development and commercialization of the Discovery Program compounds, it will be eligible to receive milestone payments of up to $10.0 million per program upon specified research and development milestones and up to $180.0 million per program upon achievement of specified regulatory and commercial milestones and will also be eligible to share in the U.S. profits at pre-determined percentages on product sales. The Company would also be eligible to receive tiered Ex-U.S. royalty rates, calculated on a product-by-product and country-by-country basis, on net sales outside of the United States, if any, ranging from low single digits to low double digits, but less then teens. If the Company does not opt in to further development and commercialization efforts for the Discovery Programs, it will be eligible to receive milestone payments of up to $70.0 million per program upon specified research and development milestones and up to $360.0 million per program upon achievement of specified regulatory and commercial milestones per approved product, if any. The Company would also be eligible to receive tiered royalties on net sales of products worldwide at royalty rates ranging from low single digits to low double digits, but less then teens. Lilly has the right to make substitutions for each of the five targets during the research term of each program, subject to certain limitations. Pursuant to the Lilly Collaboration Agreement, the Company will also participate in joint decision-making through the joint steering committee and subcommittees. Unless terminated earlier, the Lilly Collaboration Agreement will continue on a product-by-product basis until the expiration of all royalty obligations under the Lilly Collaboration Agreement and when neither the Company nor Lilly is developing, commercializing or manufacturing any product under the Lilly Collaboration Agreement. The Company or Lilly may terminate the Lilly Collaboration Agreement upon an uncured material breach by the other party. Lilly may also terminate the Lilly Collaboration Agreement in its entirety or on a target-by-target, program-by-program or product-by-product basis for any reason upon certain notice to the Company. Under the terms of the Lilly Collaboration Agreement, Lilly agreed to make a nonrefundable upfront payment of $300.0 million to the Company within thirty (30) business days following the effective date of the agreement. Simultaneously with the execution of the Lilly Collaboration Agreement, the Company and Lilly entered into the Lilly SPA, pursuant to which Lilly purchased 4,000,000 shares of the Company’s common stock at $20.00 per share, for an aggregate purchase price of $80.0 million. The Company determined that the Lilly Collaboration Agreement and the stock purchase agreement entered into with Lilly concurrently (the "Lilly SPA") should be evaluated as a combined contract in accordance with ASC 606. The Company determined the fair value of the shares sold under the Lilly SPA to be $37.8 million less than the contractual purchase price stipulated in the Lilly SPA. In accordance with the applicable accounting guidance in ASC 815-40, Contracts in Entity’s Own Equity, the Company determined that the sale of stock should be recorded at fair value and therefore allocated the excess consideration received under the Lilly SPA to the Lilly Collaboration Agreement, which along with the non-refundable payment of $300.0 million will be recognized as revenue over the total estimated period of performance. The Company accounted for the arrangement under ASC 606 as the Company concluded it has a customer relationship with Lilly. The Company determined that (1) the research activities performed by the Company for both the Joint Programs and the Discovery Programs (2) the development activities and cost sharing for the Joint Program development efforts after dose finding toxicity until registrational clinical trials (3) the research, development, manufacture and commercialization licenses and (4) service on the joint steering committee and subcommittees represent a single performance obligation under the Lilly Collaboration Agreement. The Company determined that Lilly cannot benefit from the licenses separately from the research activities, the development activities until registrational clinical trials and participation on the joint steering committee and subcommittees because these services are specialized and rely on the Company’s expertise such that these activities are highly interrelated and therefore not distinct. Accordingly, the promised goods and services represent one combined performance obligation, and the entire transaction price was allocated to that single combined performance obligation. The performance obligation will be satisfied over time as the Company performs the research activities, participates and shares in the cost of the development activities for the Joint Programs and participates in a joint steering committee and subcommittees to oversee these activities. The Company’s options to share in further development and commercialization efforts via its opt-in/opt-out rights will be assessed and accounted for as separate units of accounting under the relevant guidance if, and when, such options are exercised by the Company. The transaction price of $337.8 million was initially recorded as deferred revenue and is being recognized as revenue as the performance obligation is satisfied. The Company recognizes revenue using the cost-to-cost method, which it believes best depicts the transfer of control to the customer over time. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue is recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. As of December 31, 2021, the potential research, development and regulatory milestone payments that the Company is eligible to receive were excluded from the transaction price as they were fully constrained by uncertain events. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price. Any additions to the transaction price would be reflected in the period as a cumulative revenue catch-up based on the ratio of costs incurred to the total estimated costs expected applied to the revised transaction price. Sales-based royalties and milestone payments, which predominantly relate to the license, will be recognized if and when the related sales occur. As of December 31, 2021, the aggregate amount of the transaction price related to the unsatisfied portion of the performance obligation was $337.2 million, which is expected to be recognized as revenue through 2029. The Company does not expect collaboration revenue to be recognized evenly over this period as it will be recognized on a percentage of completion basis (using cost-to-cost method) as the Company performs the research and development activities and participates on the joint steering committee and subcommittees, which will likely vary from period to period. In estimating the total costs to satisfy its single performance obligation pursuant to the Lilly Collaboration Agreement, the Company is required to make significant estimates including an estimate of the number of target substitutions Lilly may elect to make and the expected time and expected costs to fulfill the performance obligation. The cumulative effect of revisions to the total estimated costs to complete the Company’s single performance obligation will be recorded in the period in which the changes are identified, and amounts can be reasonably estimated. While such revisions will have no impact on the Company’s cash flows, a significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods and the classification of deferred revenue between short-term and long-term. At inception, the Company assessed the Lilly Collaboration Agreement to determine whether a significant financing component exists and concluded that a significant financing component does not exist. For the year ended December 31, 2021, the Company had recorded $0.6 million of revenue under the Lilly Collaboration Agreement, which was included in deferred revenue at contract inception. As of December 31, 2021, the upfront payment of $300.0 million was recorded as collaboration receivable on the Company's consolidated balance sheets. In January 2022, the $300.0 million was collected from Lilly. Merck Collaboration Agreement In July 2020, the Company entered into a research collaboration and license agreement (the “Merck Collaboration Agreement”) with Merck Sharp & Dohme Corp. (“Merck”). The Company and Merck will apply Foghorn’s proprietary Gene Traffic Control platform to discover and develop novel therapeutics. Under the Merck Collaboration Agreement, the Company granted Merck exclusive global rights to develop, manufacture and commercialize drugs that target dysregulation of a single transcription factor. Under the terms of the Merck Collaboration Agreement, the Company and Merck are each responsible to perform certain research activities in accordance with a mutually agreed upon research plan. Merck may substitute the selected transcription factor during certain stages of the research program, subject to certain limitations. Following completion of the research program, Merck is responsible for the development and commercialization of the compounds developed pursuant to the research program and any product containing such compounds. Pursuant to the Merck Collaboration Agreement, the Company will also participate on a joint steering committee. Under the terms of the agreement, Foghorn received a nonrefundable upfront payment of $15.0 million from Merck, and is eligible to receive up to $245.0 million upon achievement of specified research, development and regulatory milestones by any product candidate generated by the collaboration, and up to $165.0 million upon achievement of specified sales-based milestones per approved product from the collaboration, if any. The Company will be eligible to receive tiered royalties, calculated on a product-by-product and country-by-country basis, on net sales of approved products from the collaboration, if any, at royalty rates ranging from the mid-single digits to low tens, depending on whether the products are covered by patent rights it licenses to Merck. Unless terminated earlier, the Merck Collaboration Agreement will continue in full force and effect until one or more products has received marketing authorization and, thereafter, until expiration of all royalty obligations under the Merck Collaboration Agreement. The Company or Merck may terminate the Merck Collaboration Agreement upon an uncured material breach by the other party or insolvency of the other party. Merck may also terminate the Merck Collaboration Agreement for any reason upon certain notice to the Company. The Company determined that the (1) research, development, manufacture and commercialization licenses, (2) the research activities performed by the Company and (3) service on the joint committees represent a single performance obligation under the Merck Collaboration Agreement. The Company determined that Merck cannot benefit from the licenses separately from the research activities and participation on the joint steering committee because these services are specialized and rely on the Company’s expertise such that these activities are highly interrelated and therefore not distinct. Accordingly, the promised goods and services represent one combined performance obligation and the entire transaction price was allocated to that single combined performance obligation. The performance obligation will be satisfied over the research term as the Company performs the research activities and participates in a joint steering committee to oversee research activities. The upfront payment of $15.0 million was initially recorded as deferred revenue and is being recognized as revenue as the performance obligation is satisfied. The Company recognizes revenue using the cost-to-cost method, which it believes best depicts the transfer of control to the customer over time. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue is recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. As of December 31, 2021, the potential research, development and regulatory milestone payments that the Company is eligible to receive were excluded from the transaction price as they were fully constrained by uncertain events. The Company will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and if necessary, the Company will adjust its estimate of the transaction price. Any additions to the transaction price would be reflected in the period as a cumulative revenue catch-up based on the ratio of costs incurred to the total estimated costs expected applied to the revised transaction price. Sales-based royalties and milestone payments, which predominantly relate to the license, will be recognized if and when the related sales occur. As of December 31, 2021, the aggregate amount of the transaction price related to the unsatisfied portion of the performance obligation is $13.9 million, which is expected to be recognized as revenue through 2028. The Company does not expect collaboration revenue to be recognized evenly over this period as it will be recognized on a percentage of completion basis (using cost-to-cost method) as the Company performs the research activities and participates on the joint steering committee, which will likely vary from period to period. In estimating the total costs to satisfy its single performance obligation pursuant to the Merck Collaboration Agreement, the Company is required to make significant estimates including an estimate of the number of transcription factor substitutions and the expected time and expected costs to fulfill the performance obligation. The cumulative effect of revisions to the total estimated costs to complete the Company’s single performance obligation will be recorded in the period in which the changes are identified, and amounts can be reasonably estimated. While such revisions will have no impact on the Company’s cash flows, a significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods and the classification of deferred revenue between short-term and long-term. In June 2021, the Company re-evaluated its estimates related to the Merck Collaboration Agreement resulting in a reclassification of $1.9 million from short-term deferred revenue to long-term deferred revenue, net of current portion on the Company's consolidated balance sheets. At inception, the Company assessed the Merck Collaboration Agreement to determine whether a significant financing component exists and concluded that a significant financing component does not exist. For the year ended December 31, 2021, the Company had recorded $0.7 million of revenue under the Merck Collaboration Agreement, which was included in deferred revenue at the beginning of the period and the classification of deferred revenue between short-term and long-term.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

During the years ended December 31, 2021 and 2020, the Company recorded no income tax benefits for the net deferred tax assets comprised primarily of net operating losses incurred and research and development tax credits generated in each year, due to its uncertainty of realizing a benefit from these items.

All of the Company’s operating losses since inception have been generated in the United States.

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate was as follows:


	Year Ended December 31,
	2021		2020
Federal statutory income tax rate	(21.0)	%	(21.0)	%
State taxes, net of federal benefit	(5.8)		(6.4)
Federal and state research and development tax credits	(4.4)		(3.7)
Other	0.8		(0.5)
Change in deferred tax asset valuation allowance	30.4		31.6
Effective income tax rate	0.0	%	0.0	%

Net deferred tax assets consisted of the following (in thousands):


	December 31,
	2021		2020
Deferred tax assets:
Net operating loss carryforwards	$	61,083	$	39,289
Research and development tax credit carryforwards	9,367		4,955
Capitalized start-up costs	157		174
Accrued expenses	5,300		1,010
Stock-based compensation	1,403		436
Operating lease liabilities	15,952		17,032
Total deferred tax assets	93,262		62,896
Deferred tax liabilities:
Depreciation	(3,551)		(2,819)
Operating lease right-of-use assets	(10,566)		(11,694)
Total deferred tax liabilities	(14,117)		(14,513)
Valuation allowance	79,145		48,383
Net deferred tax assets	$	—	$	—

As of December 31, 2021, the Company had U.S. federal and state net operating loss carryforwards of $228.9 million and $206.0 million, respectively, which may be available to offset future taxable income. The federal net operating loss carryforwards include $12.5 million which expire at various dates beginning in 2035 and $216.4 million which carryforward indefinitely but in some circumstances may be limited to offset 80% of annual taxable income. The state net operating loss carryforwards expire at various dates beginning in 2036. As of December 31, 2021, the Company also had U.S. federal and state research and development tax credit carryforwards of $6.1 million and $4.1 million, respectively, which may be available to offset future tax liabilities and expire at various dates beginning in 2036 and 2031, respectively.

Utilization of the U.S. federal and state net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, and corresponding provisions of state law, due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that can be utilized annually to offset future taxable income or tax liabilities. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain stockholders or public groups in the stock of a corporation by more than 50% over a three-year period. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. If the Company has experienced a change of control, as defined by Section 382, at any time since inception, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation under Section 382. Any limitation may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. Further, until a study is completed by the Company and any limitation is known, no amounts are being recorded as an uncertain tax position.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products that would generate revenue from product sales and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2021 and 2020. Management reevaluates the positive and negative evidence at each reporting period.

The valuation allowance increased by $30.8 million and $21.8 million during the years ended December 31, 2021 and 2020, respectively, primarily as a result of the increase in net operating loss carryforwards.

As of December 31, 2021 and 2020, the Company had not recorded any amounts for unrecognized tax benefits. The Company files income tax returns in the U.S. and Massachusetts, 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. Since the Company is in a loss carryforward position, it is generally subject to

examination by the U.S. federal, state, and local income tax authorities for all tax years in which a loss carryforward is available.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Leases

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Leases

In October 2019, the Company entered into a lease for 81,441 square feet of office and laboratory space in Cambridge, Massachusetts, commencing in January 2020 (the “New Lease”). The initial term of the New Lease was eight years with a five-year option to extend at fair-market rent at the time of the extension. The base rent payments escalate annually over the eight-year lease term and totaled approximately $60.3 million. In connection with the New Lease, the landlord agreed to fund up to $3.0 million in tenant improvements to the leased facility as well as up to an additional $16.3 million, which resulted in additional rent payments to the landlord over the lease term. During the year ended December 31, 2021 and 2020, $2.5 million and $15.4 million, respectively, of leasehold improvements were reimbursed by the landlord, which resulted in an increase to operating lease liabilities. The Company is obligated to pay its portion of real estate taxes and costs related to the premises, including costs of operations and management of the leased premises. The Company is required to maintain a cash balance of $1.7 million to secure a letter of credit associated with the lease. This amount was classified as restricted cash (non-current) on the consolidated balance sheets as of December 31, 2021 and 2020. On January 1, 2020, the lease commencement date, the Company recorded an operating lease asset of $38.6 million and corresponding lease liability of $38.3 million.

In June 2020, the Company amended the New Lease to defer payment of a portion of the base rent and operating expenses and to extend the lease term by nine months to September 2028. The amendment was accounted for as a lease modification and the right-of-use asset and lease liability were remeasured at the modification date of June 29, 2020 resulting in an increase of $7.4 million to both the right-of-use asset and lease liabilities.

The Company had a lease for office and laboratory facilities in Cambridge, Massachusetts under a noncancelable operating lease that began in August 2017 and expired in March 2025. In April 2020, this lease was assigned and assumed by a related party which became effective in October 2020.

The components of lease expense was as follows for the years ended December 31, 2021 and 2020 (in thousands):


	Year Ended December 31,
	2021		2020
Operating lease cost	$	7,547	$	7,032
Short-term lease cost	—		61
Variable lease cost	2,892		1,217
	$	10,439	$	8,310

Supplemental disclosure of cash flow information related to leases was as follows (in thousands):


	Year Ended December 31,
	2021		2020
Cash paid for amounts included in the measurement of operating lease liabilities	$	9,737	$	3,086
Operating lease liabilities arising from obtaining right-of-use assets	$	—	$	38,306
Increase in operating lease liabilities and right-of-use assets due to lease remeasurement	$	—	$	7,384

The weighted average remaining lease term and discount rate was as follows:


	2021		2020
Weighted-average remaining lease term—operating leases (in years)	6.7		7.7
Weighted-average discount rate—operating leases	5.35	%	5.35	%

Future annual minimum lease payments under operating leases as of December 31, 2021 was as follows (in thousands):


2022	$	9,954
2023	10,051
2024	10,378
2025	10,626
2026	10,881
Thereafter	19,705
Total future minimum lease payments	71,595
Less: imputed interest	(11,802)
Less: estimated lease incentives	(1,461)
Total operating lease liabilities	$	58,332


	Year Ended December 31,
Included in the consolidated balance sheets (in thousands):	2021		2020
Current operating lease liabilities	$	6,994	$	3,981
Operating lease liabilities, net of current portion	51,338		58,361
Total operating lease liabilities	$	58,332	$	62,342

Sublease agreement

In April 2020, the Company entered into a two-year sublease agreement to sublet approximately 16,843 square feet of office space under the New Lease, as amended, which began in July 2020. In February 2021, the Company entered into an amendment to the sublease to sublet approximately 2,980 square feet of additional office space to the sublessee for the remaining lease term. In July 2021, the Company entered into an amendment to, among other things, extend the sublease through November 30, 2022. As of December 31, 2021, the remaining rent payments due to the Company under the amended sublease were $1.9 million. During the years ended December 31, 2021 and 2020, the Company recorded other income of $2.5 million and $1.0 million, respectively, related to this sublease.

Leases

The components of lease expense was as follows for the years ended December 31, 2021 and 2020 (in thousands):


	Year Ended December 31,
	2021		2020
Operating lease cost	$	7,547	$	7,032
Short-term lease cost	—		61
Variable lease cost	2,892		1,217
	$	10,439	$	8,310

Supplemental disclosure of cash flow information related to leases was as follows (in thousands):


	Year Ended December 31,
	2021		2020
Cash paid for amounts included in the measurement of operating lease liabilities	$	9,737	$	3,086
Operating lease liabilities arising from obtaining right-of-use assets	$	—	$	38,306
Increase in operating lease liabilities and right-of-use assets due to lease remeasurement	$	—	$	7,384

The weighted average remaining lease term and discount rate was as follows:


	2021		2020
Weighted-average remaining lease term—operating leases (in years)	6.7		7.7
Weighted-average discount rate—operating leases	5.35	%	5.35	%

Future annual minimum lease payments under operating leases as of December 31, 2021 was as follows (in thousands):


2022	$	9,954
2023	10,051
2024	10,378
2025	10,626
2026	10,881
Thereafter	19,705
Total future minimum lease payments	71,595
Less: imputed interest	(11,802)
Less: estimated lease incentives	(1,461)
Total operating lease liabilities	$	58,332


	Year Ended December 31,
Included in the consolidated balance sheets (in thousands):	2021		2020
Current operating lease liabilities	$	6,994	$	3,981
Operating lease liabilities, net of current portion	51,338		58,361
Total operating lease liabilities	$	58,332	$	62,342

Sublease agreement

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company’s commitments under its leases are described in Note 11. License agreements The Company has entered into various exclusive and non-exclusive license agreements for certain technologies. Under the terms of these license agreements, the Company could be required to reimburse the licensors for patent expenses and remit amounts in the low single-digit as sales-based royalties upon the occurrence of specific events as outlined in the corresponding license agreements. The Company is also required to make annual license maintenance fees of less than $0.1 million and pay up to $1.1 million in regulatory milestones on each licensed product upon the occurrence of specific events as outlined in one of the license agreements. None of our product candidates utilize technologies covered by these licenses. Indemnification agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, contract research organizations, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. The Company has not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims. Legal Proceedings From time to time, the Company may become involved in litigation or other legal proceedings. The Company is not currently a party to any material litigation or legal proceedings.

Defined Contribution Plan	12 Months Ended
Defined Contribution Plan	Dec. 31, 2021
Retirement Benefits [Abstract]
Defined Contribution Plan	Defined Contribution PlanThe Company has a 401(k) defined contribution plan (the “401(k) Plan”) for its employees. Eligible employees may make pretax contributions to the 401(k) Plan up to statutory limits. There was no discretionary match made under the 401(k) Plan as of December 31, 2021 and 2020.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

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-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Parties	Related Parties In October 2015, the Company entered into a five-year service agreement with Flagship Pioneering (“Flagship”), an affiliate of one of its stockholders, Flagship Venture Funds,to provide general and administrative services to the Company, including certain consulting services and the provision of employee health and dental benefit plans for the Company’s employees. The Company made cash payments to Flagship, for services received under this agreement, of $1.2 million during the year ended December 31, 2020. As of December 31, 2021 and 2020, the Company had no accounts payable to Flagship for costs related to the service agreement. This agreement expired in 2020. In October 2015, the Company entered into a five-year consulting agreement with a scientific founder of the Company who is also a board member and a shareholder. In October 2020, this agreement was extended to January 1, 2022, and is subject to automatic one-year renewal terms until terminated. During the years ended December 31, 2021 and 2020, the Company paid the scientific founder $0.1 million and $0.2 million, respectively. As of December 31, 2021 and 2020, the Company had less than $0.1 million in accounts payable to this scientific founder.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Basis of presentation

The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Use of estimates

Concentrations of credit risk and of significant suppliers

Cash equivalents

The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents.

Marketable Securities

Restricted cash

Property and equipment


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment and software			3 years
Leasehold improvements			Shorter of useful life or remaining term of lease

Impairment of long-lived assets

Fair value measurements

•Level 1—Quoted prices in active markets for identical assets or liabilities.

Collaboration Agreements and Revenue recognition

Collaboration Agreements

Revenue recognition

Research and development costs

Patent costs

Leases

Stock-based compensation

Net loss per share

Segments

Comprehensive loss

Comprehensive lossComprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2021 and 2020, the Company’s only element of other comprehensive loss was unrealized losses on available for sale debt securities.

Income taxes

Recently issued accounting pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Property and Equipment are Stated at Cost Less Accumulated Depreciation and Amortization


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment and software			3 years
Leasehold improvements			Shorter of useful life or remaining term of lease

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2021		2020
Laboratory equipment	$	4,889	$	3,740
Furniture and fixtures	815		815
Computer equipment and software	100		100
Leasehold improvements	17,059		16,961
Assets not yet placed in service	30		15
	22,893		21,631
Less: Accumulated depreciation and amortization	(5,330)		(2,103)
	$	17,563	$	19,528

Summary of Earnings Per Share Diluted Anti Dilutive Impact


	December 31,
	2021	2020
Stock options to purchase common stock	5,920,509	5,016,460
Warrants to purchase common stock	18,445	18,445
	5,938,954	5,034,905

Marketable Securities and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Summary of Available for Sale Marketable Securities By Security Type

As of December 31, 2021, available for sale marketable securities by security type consisted of (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Commercial paper (due within one year)	$	36,246	$	—	$	(3)	$	36,243
Corporate notes and bonds (due within one year)	16,917		—		(7)		16,910
Total	$	53,163	$	—	$	(10)	$	53,153

As of December 31, 2020, available for sale marketable securities by security type consisted of (in thousands):


	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
U.S. treasury notes (due within one year)	$	92,982	$	—	$	(7)	$	92,975
Total	$	92,982	$	—	$	(7)	$	92,975

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables present the Company’s fair value hierarchy for its assets and liabilities, which were measured at fair value on a recurring basis (in thousands):


	Fair Value Measurements at December 31, 2021 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	82,252	$	—	$	—	$	82,252

Commercial paper	—		18,496		—		18,496
Marketable securities:
Commercial paper	—		36,243		—		36,243
Corporate notes and bonds	—		16,910		—		16,910
Total	$	82,252	$	71,649	$	—	$	153,901


	Fair Value Measurements at December 31, 2020 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	48,770	$	—	$	—	$	48,770
U.S. treasury notes	—		42,997		—		42,997
Marketable securities:
U.S. treasury notes	—		92,975		—		92,975
Total	$	48,770	$	135,972	$	—	$	184,742

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Sumary of Property and Equipment Net


			Estimated Useful Life
Laboratory equipment			5 years
Furniture and fixtures			5 years
Computer equipment and software			3 years
Leasehold improvements			Shorter of useful life or remaining term of lease

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2021		2020
Laboratory equipment	$	4,889	$	3,740
Furniture and fixtures	815		815
Computer equipment and software	100		100
Leasehold improvements	17,059		16,961
Assets not yet placed in service	30		15
	22,893		21,631
Less: Accumulated depreciation and amortization	(5,330)		(2,103)
	$	17,563	$	19,528

Accrued Expenses (Table)

12 Months Ended

Dec. 31, 2021

Payables and Accruals [Abstract]

Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	December 31,
	2021		2020
Accrued employee compensation and benefits	$	5,596	$	3,513
Accrued tenant improvements	13		2,385
Accrued external research and development expenses	3,079		2,146
Accrued professional fees	495		979
Other	379		138
	$	9,562	$	9,161

Notes Payable (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Summary of Long Term Debt

Long-term debt consisted of the following (in thousands):


	December 31,
	2021		2020
Principal amount of long-term debt	$	—	$	20,000
Less: Current portion of long-term debt	—		—
Long-term debt, net of current portion	—		20,000
Final payment fee	—		1,000
Debt discount, net of accretion	—		(1,346)
Long-term debt, net of discount and current portion	$	—	$	19,654

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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+ Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Schedule of Weighted-Average Assumptions Used to Estimate Fair Value of Stock Options and Restricted Stock Awards using Black-Scholes Option Pricing Model


	Year Ended December 31,
	2021		2020
Risk-free interest rate	0.7	%	0.4	%
Expected volatility	78.8	%	78.5	%
Expected dividend yield	—		—
Expected term (in years)	6.0		6.1

Schedule of Share Option Activity

The following table summarizes the Company’s option activity during the year ended December 31, 2021 which was as follows:


	Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Term	Aggregate Intrinsic Value
				(in years)	(in thousands)
Outstanding as of December 31, 2020	5,016,460	$	4.93	8.5	$	76,941
Granted	1,719,563	15.41
Exercised	(508,774)	2.79
Forfeited	(306,740)	10.22
Outstanding as of December 31, 2021	5,920,509	$	7.88	7.9	$	88,720
Vested and expected to vest as of December 31, 2021	5,920,509	$	7.88	7.9	$	88,720
Options exercisable as of December 31, 2021	2,435,439	$	3.62	7.0	$	46,882

Summary of Stock-Based Compensation Expense


	Year Ended December 31,
	2021		2020
Research and development expenses	$	4,324	$	1,724
General and administrative expenses	4,060		1,237
	$	8,384	$	2,961

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Summary of Reconciliation of the U.S. federal statutory income tax rate to the Company's effective income tax rate

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate was as follows:


	Year Ended December 31,
	2021		2020
Federal statutory income tax rate	(21.0)	%	(21.0)	%
State taxes, net of federal benefit	(5.8)		(6.4)
Federal and state research and development tax credits	(4.4)		(3.7)
Other	0.8		(0.5)
Change in deferred tax asset valuation allowance	30.4		31.6
Effective income tax rate	0.0	%	0.0	%

Summary of Net Deferred Tax Assets

Net deferred tax assets consisted of the following (in thousands):


	December 31,
	2021		2020
Deferred tax assets:
Net operating loss carryforwards	$	61,083	$	39,289
Research and development tax credit carryforwards	9,367		4,955
Capitalized start-up costs	157		174
Accrued expenses	5,300		1,010
Stock-based compensation	1,403		436
Operating lease liabilities	15,952		17,032
Total deferred tax assets	93,262		62,896
Deferred tax liabilities:
Depreciation	(3,551)		(2,819)
Operating lease right-of-use assets	(10,566)		(11,694)
Total deferred tax liabilities	(14,117)		(14,513)
Valuation allowance	79,145		48,383
Net deferred tax assets	$	—	$	—

Leases (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Summary of Lease Cost and Lease Details

The components of lease expense was as follows for the years ended December 31, 2021 and 2020 (in thousands):


	Year Ended December 31,
	2021		2020
Operating lease cost	$	7,547	$	7,032
Short-term lease cost	—		61
Variable lease cost	2,892		1,217
	$	10,439	$	8,310

Supplemental disclosure of cash flow information related to leases was as follows (in thousands):


	Year Ended December 31,
	2021		2020
Cash paid for amounts included in the measurement of operating lease liabilities	$	9,737	$	3,086
Operating lease liabilities arising from obtaining right-of-use assets	$	—	$	38,306
Increase in operating lease liabilities and right-of-use assets due to lease remeasurement	$	—	$	7,384

The weighted average remaining lease term and discount rate was as follows:


	2021		2020
Weighted-average remaining lease term—operating leases (in years)	6.7		7.7
Weighted-average discount rate—operating leases	5.35	%	5.35	%

Summary of Minimum Lease Payments

Future annual minimum lease payments under operating leases as of December 31, 2021 was as follows (in thousands):


2022	$	9,954
2023	10,051
2024	10,378
2025	10,626
2026	10,881
Thereafter	19,705
Total future minimum lease payments	71,595
Less: imputed interest	(11,802)
Less: estimated lease incentives	(1,461)
Total operating lease liabilities	$	58,332

Balance Sheet Location


	Year Ended December 31,
Included in the consolidated balance sheets (in thousands):	2021		2020
Current operating lease liabilities	$	6,994	$	3,981
Operating lease liabilities, net of current portion	51,338		58,361
Total operating lease liabilities	$	58,332	$	62,342

Nature of Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		12 Months Ended
	Dec. 10, 2021	Nov. 19, 2020	Oct. 27, 2020	Jan. 31, 2022	Jul. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements
Upfront payment received					$ 15,000	$ 15,000
Net loss						(101,320)	$ (68,800)
Accumulated deficit						$ 264,256	$ 162,936
Eli Lilly \| Subsequent Event
Organization Consolidation And Presentation Of Financial Statements
Upfront payment received				$ 300,000
IPO
Organization Consolidation And Presentation Of Financial Statements
Stock issued during the period shares new issues shares (in shares)			7,500,000
Sale of stock issue price per share (in dollars per share)			$ 16.00
Sale of stock consideration received on the transaction			$ 107,900
IPO \| Common Stock
Organization Consolidation And Presentation Of Financial Statements
Stock issued during the period shares new issues shares (in shares)			7,500,000
Sale of stock issue price per share (in dollars per share)			$ 16.00
Sale of stock consideration received on the transaction			$ 107,900
Over-Allotment Option
Organization Consolidation And Presentation Of Financial Statements
Stock issued during the period shares new issues shares (in shares)		951,837
Sale of stock issue price per share (in dollars per share)		$ 16.00
Sale of stock consideration received on the transaction		$ 14,200
Over-Allotment Option \| Common Stock
Organization Consolidation And Presentation Of Financial Statements
Stock issued during the period shares new issues shares (in shares)		951,837
Sale of stock issue price per share (in dollars per share)		$ 16.00
Sale of stock consideration received on the transaction		$ 14,200
Share Purchase Agreement \| Eli Lilly
Organization Consolidation And Presentation Of Financial Statements
Sale of stock issue price per share (in dollars per share)	$ 20.00
Sale of stock consideration received on the transaction	$ 80,000
Sale of stock, number of shares issued in transaction (in shares)	4,000,000
Share Purchase Agreement \| Eli Lilly \| Common Stock
Organization Consolidation And Presentation Of Financial Statements
Sale of stock consideration received on the transaction	$ 42,200

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) agreement	Dec. 31, 2020 USD ($)
Subsidiary, Sale of Stock
Number of collaborative agreements \| agreement	2
Impairment losses on long-lived assets \| $	$ 0	$ 0

Summary of Significant Accounting Policies - Summary of Property and Equipment are Stated at Cost Less Accumulated Depreciation and Amortization (Details)	12 Months Ended
	Dec. 31, 2021
Laboratory equipment
Property, Plant and Equipment
Property, plant and equipment, useful life	5 years
Furniture and fixtures
Property, Plant and Equipment
Property, plant and equipment, useful life	5 years
Computer equipment and software
Property, Plant and Equipment
Property, plant and equipment, useful life	3 years

Summary of Significant Accounting Policies - Summary of Earnings Per Share Diluted Anti Dilutive Impact (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per share, amount	5,938,954	5,034,905
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per share, amount	5,920,509	5,016,460
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from computation of earnings per share, amount	18,445	18,445

Marketable Securities and Fair Value Measurements - Summary of Available for Sale Marketable Securities By Security Type (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Amortized Cost	$ 53,163	$ 92,982
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(10)	(7)
Estimated Fair Value	53,153	92,975
Commercial paper (due within one year)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Amortized Cost	36,246
Gross Unrealized Gains	0
Gross Unrealized Losses	(3)
Estimated Fair Value	36,243
Corporate notes and bonds (due within one year)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Amortized Cost	16,917
Gross Unrealized Gains	0
Gross Unrealized Losses	(7)
Estimated Fair Value	$ 16,910
U.S. treasury notes (due within one year)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Amortized Cost		92,982
Gross Unrealized Gains		0
Gross Unrealized Losses		(7)
Estimated Fair Value		$ 92,975

Marketable Securities and Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	$ 53,153	$ 92,975
Assets, fair value		184,742
U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents		42,997
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	82,252	48,770
Level 1 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	71,649	135,972
Level 2 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents		42,997
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	0	0
Level 3 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents		0
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, fair value	153,901
Recurring \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	36,243
Recurring \| Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	16,910
Recurring \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities		92,975
Recurring \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	82,252	48,770
Recurring \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	18,496
Recurring \| Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	0
Recurring \| Level 1 \| Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	0
Recurring \| Level 1 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities		0
Recurring \| Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	82,252	48,770
Recurring \| Level 1 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0
Recurring \| Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	36,243
Recurring \| Level 2 \| Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	16,910
Recurring \| Level 2 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities		92,975
Recurring \| Level 2 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0	0
Recurring \| Level 2 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	18,496
Recurring \| Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	0
Recurring \| Level 3 \| Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities	0
Recurring \| Level 3 \| U.S. treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Marketable securities		0
Recurring \| Level 3 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0	$ 0
Recurring \| Level 3 \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	$ 0

Property and Equipment, Net - Summary of Property and Equipment Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Property, plant and equipment, gross	$ 22,893	$ 21,631
Less: Accumulated depreciation and amortization	(5,330)	(2,103)
Property, plant and equipment, net	17,563	19,528
Laboratory equipment
Property, Plant and Equipment
Property, plant and equipment, gross	4,889	3,740
Furniture and fixtures
Property, Plant and Equipment
Property, plant and equipment, gross	815	815
Computer equipment and software
Property, Plant and Equipment
Property, plant and equipment, gross	100	100
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	17,059	16,961
Assets not yet placed in service
Property, Plant and Equipment
Property, plant and equipment, gross	$ 30	$ 15

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 3,227	$ 1,327

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 5,596	$ 3,513
Accrued tenant improvements	13	2,385
Accrued external research and development expenses	3,079	2,146
Accrued professional fees	495	979
Other	379	138
Total	$ 9,562	$ 9,161

Notes Payable - Summary of Long Term Debt (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Nov. 19, 2020
Short-term Debt
Notes payable, net of discount	$ 0	$ 19,654,000
Term Loan A
Short-term Debt
Principal amount of long-term debt	0	20,000,000	$ 20,000,000
Less: Current portion of long-term debt	0	0
Notes payable, net of discount	0	20,000,000
Final payment fee	0	1,000,000
Debt discount, net of accretion	0	(1,346,000)
Long-term debt, net of discount and current portion	$ 0	$ 19,654,000

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References + Details

Notes Payable - Additional Information (Details) - USD ($)		1 Months Ended	12 Months Ended
	Nov. 19, 2020	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt
Loss on debt extinguishment		$ (1,200,000)	$ (1,233,000)	$ (222,000)
Debt, weighted average interest rate			9.50%	6.40%
Term Loan A
Short-term Debt
Aggregate principal amount	$ 20,000,000	$ 0	$ 0	$ 20,000,000
Debt instrument, interest rate, stated percentage	8.00%
Debt instrument, basis spread on variable rate	7.84%
Debt, final payment fee percentage	5.00%
Class of warrant or right, number of securities called by warrants or rights (in shares)	18,445
Warrants Issue price per share (in dollars per share)	$ 16.26
Warrants exercisable term	10 years
Warrants not settlable in cash, fair value disclosure	$ 200,000
Term of loan	5 years
Payments of debt issuance costs	$ 200,000
Term Loan A \| Prepayment Period One
Short-term Debt
Percentage of prepayment fee	2.00%
Term Loan A \| Prepayment Period Two
Short-term Debt
Percentage of prepayment fee	1.00%
Term Loan A \| Prepayment Period Three
Short-term Debt
Percentage of prepayment fee	0.50%
Term Loan A \| Maximum \| Prepayment Period One
Short-term Debt
Prepayment period	12 months
Term Loan A \| Maximum \| Prepayment Period Two
Short-term Debt
Prepayment period	24 months
Term Loan A \| Minimum \| Prepayment Period Two
Short-term Debt
Prepayment period	12 months
Term Loan A \| Minimum \| Prepayment Period Three
Short-term Debt
Prepayment period	24 months
Term Loan B
Short-term Debt
Principal amount of long-term debt	$ 5,000,000

Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 10, 2021	Nov. 19, 2020	Oct. 27, 2020
IPO
Class of Stock
Stock issued during the period shares new issues shares (in shares)			7,500,000
Sale of stock issue price per share (in dollars per share)			$ 16.00
Sale of stock consideration received on the transaction			$ 107.9
IPO \| Common Stock
Class of Stock
Stock issued during the period shares new issues shares (in shares)			7,500,000
Sale of stock issue price per share (in dollars per share)			$ 16.00
Sale of stock consideration received on the transaction			$ 107.9
Over-Allotment Option
Class of Stock
Stock issued during the period shares new issues shares (in shares)		951,837
Sale of stock issue price per share (in dollars per share)		$ 16.00
Sale of stock consideration received on the transaction		$ 14.2
Over-Allotment Option \| Common Stock
Class of Stock
Stock issued during the period shares new issues shares (in shares)		951,837
Sale of stock issue price per share (in dollars per share)		$ 16.00
Sale of stock consideration received on the transaction		$ 14.2
Share Purchase Agreement \| Eli Lilly
Class of Stock
Sale of stock issue price per share (in dollars per share)	$ 20.00
Sale of stock consideration received on the transaction	$ 80.0
Sale of stock, number of shares issued in transaction (in shares)	4,000,000
Share Purchase Agreement \| Common Stock \| Eli Lilly
Class of Stock
Sale of stock consideration received on the transaction	$ 42.2

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		12 Months Ended
	Jan. 01, 2022	Oct. 21, 2020	Apr. 30, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2015
Share-based Payment Arrangement
Aggregate intrinsic value of stock options exercised				$ 5.3	$ 3.5
Weighted average grant-date fair value of stock options granted (in dollars per share)				$ 10.40	$ 6.01
Aggregate fair value of restricted stock that vested					$ 4.8
Unrecognized compensation costs related to unvested options and unvested restricted stock				$ 20.8
Weighted average period of unrecognized compensation costs				2 years 8 months 12 days
Subsequent Event
Share-based Payment Arrangement
Number of shares authorized (in shares)	780,891
Restricted Stock
Share-based Payment Arrangement
Vesting period (years)			5 years
Sale of restricted common stock to scientific founders (in shares)						4,459,459
2020 Incentive Plan
Share-based Payment Arrangement
Number of shares authorized (in shares)				2,200,000
Common stock shares available for grant (in shares)				2,271,847
Percentage of automatic annual increase in number of shares				4.00%
Vesting period (years)				4 years
Stock option expiry period (years)				10 years
2020 Incentive Plan \| Subsequent Event
Share-based Payment Arrangement
Number of additional shares authorized (in shares)	1,651,989
2016 Incentive Plan
Share-based Payment Arrangement
Number of shares authorized (in shares)				5,078,295
2020 Employee Stock Purchase Plan
Share-based Payment Arrangement
Number of shares authorized (in shares)		360,000
Percentage of automatic annual increase in number of shares		1.00%
Maximum aggregate number of shares added to plan (in shares)				3,220,520
2020 Employee Stock Purchase Plan \| Subsequent Event
Share-based Payment Arrangement
Number of additional shares authorized (in shares)	367,894

Stock-Based Compensation - Schedule of Weighted Average Assumptions Used to Estimate Fair Value of Stock Options and Restricted Stock Awards using Black-Scholes Option Pricing Model (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	0.70%	0.40%
Expected volatility	78.80%	78.50%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	6 years	6 years 1 month 6 days

Stock-Based Compensation - Schedule of Share Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Beginning Balance (in shares)	5,016,460
Granted (in shares)	1,719,563
Exercised (in shares)	(508,774)
Forfeited (in shares)	(306,740)
Ending Balance (in shares)	5,920,509	5,016,460
Vested and expected to vest (in shares)	5,920,509
Options exercisable (in shares)	2,435,439
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 4.93
Granted (in dollars per share)	15.41
Exercised (in dollars per share)	2.79
Forfeited (in dollars per share)	10.22
Ending balance (in dollars per share)	7.88	$ 4.93
Vested and expected to vest (in dollars per share)	7.88
Options, exercisable (in dollars per share)	$ 3.62
Weighted Average Contractual Term
Outstanding	7 years 10 months 24 days	8 years 6 months
Vested and expected to vest	7 years 10 months 24 days
Options exercisable	7 years
Aggregate Intrinsic Value
Outstanding	$ 88,720	$ 76,941
Vested and expected to vest	88,720
Options exercisable	$ 46,882

Stock-Based Compensation - Summary of Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement
Stock-based compensation expense related to issuance of options and employee stock purchase plan	$ 8,384	$ 2,961
Research and development expenses
Share-based Payment Arrangement
Stock-based compensation expense related to issuance of options and employee stock purchase plan	4,324	1,724
General and administrative expenses
Share-based Payment Arrangement
Stock-based compensation expense related to issuance of options and employee stock purchase plan	$ 4,060	$ 1,237

Collaboration Agreement (Details) $ / shares in Units, $ in Thousands		1 Months Ended			12 Months Ended
	Dec. 10, 2021 USD ($) $ / shares shares	Jan. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) target program	Jul. 31, 2020 USD ($)	Dec. 31, 2021 USD ($) target program	Dec. 31, 2020 USD ($)	Dec. 01, 2021 USD ($)	Jun. 30, 2021 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative
Upfront payment received				$ 15,000	$ 15,000
Revenue					1,319	$ 430
Collaboration receivable			$ 300,000		300,000	0
Deferred revenue, current			$ 28,317		$ 28,317	2,024
Scenario, Adjustment
Collaborative Arrangement and Arrangement Other than Collaborative
Deferred revenue, current								$ 1,900
Eli Lilly
Collaborative Arrangement and Arrangement Other than Collaborative
Number of additional targets \| target			3
Number of programs \| program			6		6
Number of targets \| target			5		5
Difference between fair value of shares and contract price			$ 37,800
Revenue					$ 600
Deferred revenue			337,200		337,200		$ 337,800
Eli Lilly \| Share Purchase Agreement
Collaborative Arrangement and Arrangement Other than Collaborative
Sale of stock, number of shares issued in transaction (in shares) \| shares	4,000,000
Sale of stock issue price per share (in dollars per share) \| $ / shares	$ 20.00
Sale of stock consideration received on the transaction	$ 80,000
Eli Lilly \| Subsequent Event
Collaborative Arrangement and Arrangement Other than Collaborative
Upfront payment received		$ 300,000
Merck
Collaborative Arrangement and Arrangement Other than Collaborative
Revenue					700
Deferred revenue			15,000		15,000
Unsatisfied portion of the performance obligation						$ 13,900
Maximum \| Sales based
Collaborative Arrangement and Arrangement Other than Collaborative
Amount receivable for achievement of milestones					165,000
Research Development And Regulatory \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative
Amount receivable for achievement of milestones					$ 245,000
Research Development And Regulatory \| Maximum \| Eli Lilly
Collaborative Arrangement and Arrangement Other than Collaborative
Amount receivable for achievement of milestones			10,000
Amounts receivable for opt out milestones			70,000
Sales Based Milestone \| Eli Lilly
Collaborative Arrangement and Arrangement Other than Collaborative
Amount receivable for achievement of milestones			180,000
Amounts receivable for opt out milestones			$ 360,000

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency
Increase in valuation allowance	$ 30,800,000	$ 21,800,000
Unrecognized tax benefits	0	$ 0
Domestic Tax Authority
Income Tax Contingency
Operating loss carry forward	228,900,000
Operating loss subject to expiration expiration	12,500,000
Operating loss without expiration	$ 216,400,000
Operating loss carryforward limit percentage	80.00%
Tax credit carry forward	$ 6,100,000
State and Local Jurisdiction
Income Tax Contingency
Operating loss carry forward	206,000,000
Tax credit carry forward	$ 4,100,000

Income Taxes - Summary of Reconciliation of the U.S. federal statutory income tax rate to the Company's effective income tax rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)
State taxes, net of federal benefit	(5.80%)	(6.40%)
Federal and state research and development tax credits	(4.40%)	(3.70%)
Other	0.80%	(0.50%)
Change in deferred tax asset valuation allowance	30.40%	31.60%
Effective income tax rate	0.00%	0.00%

Income Taxes - Summary of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 61,083	$ 39,289
Research and development tax credit carryforwards	9,367	4,955
Capitalized start-up costs	157	174
Accrued expenses	5,300	1,010
Stock-based compensation	1,403	436
Operating lease liabilities	15,952	17,032
Total deferred tax assets	93,262	62,896
Deferred tax liabilities:
Depreciation	(3,551)	(2,819)
Operating lease right-of-use assets	(10,566)	(11,694)
Total deferred tax liabilities	(14,117)	(14,513)
Valuation allowance	79,145	48,383
Net deferred tax assets	$ 0	$ 0

Leases - Additional Information (Details) $ in Thousands	12 Months Ended		96 Months Ended
Leases - Additional Information (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2027 USD ($)	Feb. 28, 2021 ft²	Jun. 29, 2020 USD ($)	Apr. 30, 2020 ft²	Jan. 01, 2020 USD ($)	Oct. 31, 2019 USD ($) ft²
Lessee, Lease, Description
Restricted cash	$ 1,733	$ 1,733
Operating lease right-of-use assets	38,516	42,804
Operating lease liability	58,332	62,342
Future sublease income outstanding	1,900
Sublease income recorded as other income	2,500	1,000
Office and Laboratory Space In Cambridge, Massachusetts
Lessee, Lease, Description
Area of leased property \| ft²								81,441
Lessee, operating lease, term of contract								8 years
Operating lease term extension								5 years
Reimbursements from lessor	2,500	$ 15,400
Restricted cash	$ 1,700
Operating lease right-of-use assets							$ 38,600
Operating lease liability							$ 38,300
Office and Laboratory Space In Cambridge, Massachusetts \| Forecast
Lessee, Lease, Description
Operating lease rent payments			$ 60,300
Office and Laboratory Space In Cambridge, Massachusetts \| Scenario, Adjustment
Lessee, Lease, Description
Operating lease right-of-use assets					$ 7,400
Operating lease liability					$ 7,400
Office Space In Cambridge, Massachusetts
Lessee, Lease, Description
Area of leased property \| ft²						16,843
Lessor, operating lease, term of contract						2 years
Additional Office Space In Cambridge, Massachusetts
Lessee, Lease, Description
Area of leased property \| ft²				2,980
Maximum \| Office and Laboratory Space In Cambridge, Massachusetts
Lessee, Lease, Description
Leasehold improvements landlord allowance								$ 3,000
Leasehold improvements landlord allowance to be repaid								$ 16,300

Leases - Summary of Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease cost	$ 7,547	$ 7,032
Short-term lease cost	0	61
Variable lease cost	2,892	1,217
Total	$ 10,439	$ 8,310

Leases - Summary of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 9,737	$ 3,086
Operating lease liabilities arising from obtaining right-of-use assets	0	38,306
Increase in operating lease liabilities and right-of-use assets due to lease remeasurement	$ 0	$ 7,384

Leases - Summary of Weighted-Average Remaining Lease Term and Discount Rate Leases (Details)	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Weighted-average remaining lease term—operating leases (in years)	6 years 8 months 12 days	7 years 8 months 12 days
Weighted-average discount rate—operating leases	5.35%	5.35%

Leases - Summary of Minimum Lease Payment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Lessee, Operating Lease, Liability, Payment, Due
2022	$ 9,954
2023	10,051
2024	10,378
2025	10,626
2026	10,881
Thereafter	19,705
Total future minimum lease payments	71,595
Less: imputed interest	(11,802)
Less: estimated lease incentives	(1,461)
Operating lease liability	$ 58,332	$ 62,342

Leases - Summary of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Current operating lease liabilities	$ 6,994	$ 3,981
Operating lease liabilities, net of current portion	51,338	58,361
Total operating lease liabilities	$ 58,332	$ 62,342

Commitments and Contingencies (Details) - Stanford License Agreement - Maximum $ in Millions	Jul. 31, 2017 USD ($)
Contingencies
Annual license maintenance fees	$ 0.1
Milestones payable upon event	$ 1.1

Related Parties (Details) - USD ($)		1 Months Ended	12 Months Ended
Related Parties (Details) - USD ($)	Jan. 01, 2022	Oct. 31, 2015	Dec. 31, 2021	Dec. 31, 2020
Subsequent Event
Related Party Transaction
Service agreement renewal term	1 year
Affiliated Entity
Related Party Transaction
Payments made to related party under service agreement				$ 1,200,000
Accounts payable, related party			$ 0	0
Affiliated Entity \| Director
Related Party Transaction
Service agreement term		5 years
Payments made to related party under service agreement			100,000	$ 200,000
Affiliated Entity \| Scientific Founder
Related Party Transaction
Accounts payable, related party			$ 100,000
Flagship Pioneering \| Affiliated Entity
Related Party Transaction
Service agreement term		5 years