Enliven Therapeutics (ELVN) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Entity Registrant Name	IMARA INC.
Document Type	10-Q
Trading Symbol	IMRA
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		26,275,722
Amendment Flag	false
Entity Central Index Key	0001672619
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-39247
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1523849
Entity Address, Address Line One	116 Huntington Avenue
Entity Address, Address Line Two	6th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02116
City Area Code	617
Local Phone Number	206-2020
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 75,295	$ 47,698
Short-term investments	27,544	40,524
Prepaid expenses and other current assets	3,158	2,183
Total current assets	105,997	90,405
Property and equipment, net	275	349
Right of use assets - operating leases	580
Other assets	175	88
Total assets	107,027	90,842
Current liabilities:
Accounts payable	2,476	1,971
Accrued expenses and other current liabilities	4,462	4,276
Operating lease liability, current	250
Total current liabilities	7,188	6,247
Deferred rent		160
Operating lease liability, non-current	466
Total liabilities	7,654	6,407
Commitments and contingencies (Note 7)
Preferred stock, $0.001 par value per share; 10,000,000 shares authorized; no shares issued or outstanding as of September 30, 2021; no shares authorized, issued or outstanding as of December 31, 2020
Common stock, $0.001 par value per share; 200,000,000 shares authorized as of September 30, 2021 and December 31, 2020, respectively; 26,275,722 and 17,548,263 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	27	18
Additional paid-in capital	232,526	180,526
Accumulated other comprehensive income	(2)	4
Accumulated deficit	(133,178)	(96,113)
Total stockholders’ equity	99,373	84,435
Total liabilities and stockholders’ equity	$ 107,027	$ 90,842

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	26,275,722	17,548,263
Common stock, shares outstanding	26,275,722	17,548,263

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses:
Research and development	$ 10,397	$ 9,533	$ 27,586	$ 23,195
General and administrative	3,262	2,961	9,522	6,953
Total operating expenses	13,659	12,494	37,108	30,148
Loss from operations	(13,659)	(12,494)	(37,108)	(30,148)
Total other income, (net):
Interest income	30	126	161	368
Other expense	(18)	(55)	(118)	(62)
Total other income, (net)	12	71	43	306
Net loss	(13,647)	(12,423)	(37,065)	(29,842)
Accretion of Series B convertible preferred stock			(7,900)	(7,858)
Net loss attributable to common stockholders—basic and diluted	$ (13,647)	$ (12,423)	$ (37,065)	$ (37,700)
Weighted-average common shares outstanding—basic and diluted	24,898,346	17,349,813	20,099,976	12,696,368
Net loss per share attributable to common stockholders—basic and diluted	$ (0.55)	$ (0.72)	$ (1.84)	$ (2.97)
Comprehensive loss:
Net loss	$ (13,647)	$ (12,423)	$ (37,065)	$ (29,842)
Other comprehensive income:
Unrealized loss on investments	(2)	(24)	(6)	(8)
Comprehensive loss	$ (13,649)	$ (12,447)	$ (37,071)	$ (29,850)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Initial Public Offering	July 2021 Offering	CONVERTIBLE PREFERRED STOCK SERIES SEED	CONVERTIBLE PREFERRED STOCK SERIES A	CONVERTIBLE PREFERRED STOCK SERIES B	COMMON STOCK	COMMON STOCKInitial Public Offering	COMMON STOCKJuly 2021 Offering	ADDITIONAL PAID-IN CAPITAL	ADDITIONAL PAID-IN CAPITALInitial Public Offering	ADDITIONAL PAID-IN CAPITALJuly 2021 Offering	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED DEFICIT
Beginning balance at Dec. 31, 2019	$ (48,848)						$ 1			$ 5,872			$ 32	$ (54,753)
Beginning balance, shares at Dec. 31, 2019							702,510
Beginning balance, convertible preferred stock at Dec. 31, 2019				$ 1,460	$ 30,729	$ 45,575
Beginning balance, convertible preferred stock, shares at Dec. 31, 2019				2,712,960	31,499,040	26,321,313
Issuance of Series B convertible preferred stock, net of issuance costs and beneficial conversion charge	7,858					$ 9,271				7,858
Issuance of Series B convertible preferred stock, net of issuance costs and beneficial conversion charge, shares						9,845,348
Accretion of Series B converted preferred stock	(7,858)									(7,858)
Accretion of Series B converted preferred stock						$ 7,858
Conversion of convertible preferred stock into common stock	94,893			$ (1,460)	$ (30,729)	$ (62,704)	$ 11			94,882
Conversion of convertible preferred stock into common stock, shares				(2,712,960)	(31,499,040)	(36,166,661)	11,172,955
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs		$ 66,052						$ 5			$ 66,047
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs, shares								4,700,000
Stock-based compensation expense	360									360
Unrealized gain (loss) on investments	(48)												(48)
Net loss	(7,215)													(7,215)
Ending balance at Mar. 31, 2020	105,194						$ 17			167,161			(16)	(61,968)
Ending balance, shares at Mar. 31, 2020							16,575,465
Beginning balance at Dec. 31, 2019	(48,848)						$ 1			5,872			32	(54,753)
Beginning balance, shares at Dec. 31, 2019							702,510
Beginning balance, convertible preferred stock at Dec. 31, 2019				$ 1,460	$ 30,729	$ 45,575
Beginning balance, convertible preferred stock, shares at Dec. 31, 2019				2,712,960	31,499,040	26,321,313
Net loss	(29,842)
Ending balance at Sep. 30, 2020	94,698						$ 18			179,251			24	(84,595)
Ending balance, shares at Sep. 30, 2020							17,377,067
Beginning balance at Mar. 31, 2020	105,194						$ 17			167,161			(16)	(61,968)
Beginning balance, shares at Mar. 31, 2020							16,575,465
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs		$ 10,474						$ 1			$ 10,473
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs, shares								705,000
Exercise of stock options	218									218
Exercise of stock options, shares							44,271
Stock-based compensation expense	550									550
Unrealized gain (loss) on investments	64												64
Net loss	(10,204)													(10,204)
Ending balance at Jun. 30, 2020	106,296						$ 18			178,402			48	(72,172)
Ending balance, shares at Jun. 30, 2020							17,324,736
Exercise of stock options	207									207
Exercise of stock options, shares							52,331
Stock-based compensation expense	642									642
Unrealized gain (loss) on investments	(24)												(24)
Net loss	(12,423)													(12,423)
Ending balance at Sep. 30, 2020	94,698						$ 18			179,251			24	(84,595)
Ending balance, shares at Sep. 30, 2020							17,377,067
Beginning balance at Dec. 31, 2020	84,435						$ 18			180,526			4	(96,113)
Beginning balance, shares at Dec. 31, 2020							17,548,263
Exercise of stock options	472									472
Exercise of stock options, shares							68,279
Stock-based compensation expense	947									947
Unrealized gain (loss) on investments	(3)												(3)
Net loss	(10,257)													(10,257)
Ending balance at Mar. 31, 2021	75,594						$ 18			181,945			1	(106,370)
Ending balance, shares at Mar. 31, 2021							17,616,542
Beginning balance at Dec. 31, 2020	$ 84,435						$ 18			180,526			4	(96,113)
Beginning balance, shares at Dec. 31, 2020							17,548,263
Exercise of stock options, shares	158,681
Net loss	$ (37,065)
Ending balance at Sep. 30, 2021	99,373						$ 27			232,526			(2)	(133,178)
Ending balance, shares at Sep. 30, 2021							26,275,722
Beginning balance at Mar. 31, 2021	75,594						$ 18			181,945			1	(106,370)
Beginning balance, shares at Mar. 31, 2021							17,616,542
Stock-based compensation expense	917									917
Issuance of common stock under ATM offering, net of issuance costs	1,345						$ 1			1,344
Issuance of common stock under ATM offering, net of issuance costs, shares							231,291
Exercise of stock options and issuance of stock under the Employee Stock Purchase Plan	273									273
Exercise of stock options and issuance of stock under the Employee Stock Purchase Plan, shares							63,104
Unrealized gain (loss) on investments	(1)												(1)
Net loss	(13,161)													(13,161)
Ending balance at Jun. 30, 2021	64,967						$ 19			184,479				(119,531)
Ending balance, shares at Jun. 30, 2021							17,910,937
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs			$ 46,907						$ 8			$ 46,899
Issuance of common stock, net of underwriting discounts, commissions, offering costs and issuance costs, shares									8,333,333
Exercise of stock options	145									145
Exercise of stock options, shares							31,452
Stock-based compensation expense	1,003									1,003
Unrealized gain (loss) on investments	(2)												(2)
Net loss	(13,647)													(13,647)
Ending balance at Sep. 30, 2021	$ 99,373						$ 27			$ 232,526			$ (2)	$ (133,178)
Ending balance, shares at Sep. 30, 2021							26,275,722

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2021	Sep. 30, 2020
Common stock, par value	$ 0.001
Initial Public Offering
Underwriting discounts, commissions and offering costs		$ 17	$ 3,885
July 2021 Offering
Stock issuance costs	$ 210
COMMON STOCK
Common stock, par value	$ 0.001	$ 0.001	$ 0.001	$ 0.001	$ 0.001
CONVERTIBLE PREFERRED STOCK SERIES SEED
Convertible preferred stock, par value		0.001	0.001		0.001
CONVERTIBLE PREFERRED STOCK SERIES A
Convertible preferred stock, par value		0.001	0.001		0.001
CONVERTIBLE PREFERRED STOCK SERIES B
Convertible preferred stock, par value		$ 0.001	$ 0.001		$ 0.001
Stock issuance costs			$ 20

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (37,065)	$ (29,842)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,867	1,552
Depreciation expense	74	74
Amortization and accretion on investments	103	(57)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(975)	(1,905)
Accounts payable	505	228
Accrued expenses and other current liabilities	229	898
Deferred rent		(17)
Operating lease assets and liabilities, net	(24)
Other Assets		(60)
Net cash used in operating activities	(34,286)	(29,129)
Cash flows from investing activities:
Proceeds from maturities and sales of short-term investments	42,637	17,900
Purchases of short-term investments	(29,766)	(55,811)
Purchases of property and equipment	(12)	(22)
Net cash provided by investing activities	12,859	(37,933)
Cash flows from financing activities:
Proceeds from issuance of Series B convertible preferred stock, net of issuance costs		17,150
Proceeds from initial public offering, net of underwriting discounts and commissions		80,427
Proceeds from July 2021 offering, net of underwriting discounts and commissions	47,000
Proceeds from ATM offering, net of underwriting discounts and commissions	1,818	7,858
Payment of issuance costs	(567)	(1,718)
Proceeds from exercise of options	860	425
Net cash provided by financing activities	49,111	96,284
Net increase in cash, cash equivalents and restricted cash	27,684	29,222
Cash, cash equivalents and restricted cash, beginning of period	47,786	5,024
Cash, cash equivalents and restricted cash, end of period	75,470	34,246
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock		94,893
Proceeds from ATM offering, net of underwriting discounts and commissions	1,818	7,858
Reclassification of deferred offering costs from other assets to additional paid-in capital		2,144
Deferred offering costs included in accounts payable and accrued expenses		369
Property and equipment purchases included in accrued expenses		14
Unrealized loss on investments	$ (6)	$ (8)

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Statement Of Cash Flows [Abstract]
Cash and cash equivalents	$ 75,295	$ 34,158
Restricted cash (included in other assets)	175	88
Total cash, cash equivalents and restricted cash	$ 75,470	$ 34,246

Nature of the Business

Nature of the Business	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business IMARA Inc. (“IMARA” or the “Company”) is a clinical-stage biopharmaceutical company dedicated to developing and commercializing novel therapeutics to treat rare inherited genetic disorders of hemoglobin, known as hemoglobinopathies, which have significant unmet medical need. The Company was incorporated in January 2016 under the laws of the State of Delaware, and its principal offices are in Boston, Massachusetts. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including but not limited to, risks associated with completing preclinical studies and clinical trials, receiving regulatory approvals for product candidates, development by competitors of new biopharmaceutical products, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. The Company’s lead product candidate currently under development, t In February 2020, the Company effected a 1-for-6.299 reverse stock split of the Company’s issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each of the Company’s outstanding series of preferred stock. All share and per share amounts in the unaudited condensed consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to the reverse stock split, including reclassifying an amount equal to the change in par value of common stock to additional paid-in capital. On February 25, 2020, the Company issued and sold 1,562,994‬ shares of Series B convertible preferred stock (“Series B Preferred Stock”), at a price of $10.9722 per share, upon a waiver of specified milestone conditions from the holders of a majority of the shares then held by holders of Series B Preferred Stock, and raised approximately $17.1 million in net proceeds after deducting less than $0.1 million of issuance costs. On March 16, 2020, the Company completed an initial public offering (“IPO”) of its common stock and issued and sold 4,700,000 shares of common stock at a public offering price of $16.00 per share, resulting in gross proceeds of $75.2 million. On April 13, 2020, the Company issued and sold an additional 705,000 shares of common stock pursuant to the exercise of the underwriters’ option to purchase additional shares for aggregate gross proceeds of $11.3 million. Inclusive of the exercise by the underwriters of their option to purchase additional shares, the Company received approximately $76.5 million in net proceeds from the IPO after deducting $10.0 million of underwriting discounts and commissions and offering expenses. Upon the closing of the IPO, all 70,378,661 shares of outstanding preferred stock automatically converted into 11,172,955 shares of common stock. Upon conversion of the convertible preferred stock, the Company reclassified the carrying value of the convertible preferred stock to common stock and additional paid-in capital. On April 1, 2021, the Company filed a Registration Statement on Form S-3 (the “Shelf”) with the SEC in relation to the registration and potential future issuance of common stock, preferred stock, debt securities, warrants and/or units of any combination thereof in the aggregate amount of up to $200.0 million. The Shelf was declared effective on April 8, 2021. The Company also simultaneously entered into a sales agreement with Cantor Fitzgerald & Co, LLC, as sales agent, providing for the offering, issuance and sale by the Company of up to an aggregate $75.0 million of its common stock from time to time in “at-the-market” offerings under the Shelf. As of September 30, 2021, the Company had issued and sold 231,291 shares of common stock under the sales agreement, resulting in net proceeds of $1.5 million after deducting commissions and offering expenses. On July 16, 2021, the Company completed a public offering of shares of its common stock. In connection with the offering, the Company issued and sold 8,333,333 shares of common stock at a public offering price of $6.00 per share, resulting in net proceeds of $46.8 million after deducting underwriting discounts and commissions and offering expenses. Liquidity The Company has incurred recurring negative cash flows since inception and has funded its operations primarily from the sale of convertible preferred stock and proceeds from the IPO and subsequent common stock offerings. As of September 30, 2021, the Company had cash, cash equivalents and investments of $ 102.8 million and an accumulated deficit of approximately $ million. The Company expects its operating losses and negative operating cash flows to continue into the foreseeable future as it continues to expand its research and development efforts . The Company believes its cash, cash equivalents and investments as of September 30, 2021 will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the date of filing this Quarterly Report on Form 10-Q. The Company will need additional funding to support its planned operating activities. There can be no assurances, however, that the current operating plan will be achieved or that additional funding will be available on terms acceptable to the Company, or at all. If the Company is unable to obtain sufficient funding, it could be required to delay its development efforts, limit activities and reduce research and development costs, which could adversely affect its business prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). 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 as amended by Accounting Standards Updates of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s Annual Report on Form 10-K (the “Annual Report”), filed with the SEC on March 5, 2021. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited financial statements, with the exception of the modified retrospective adoption of ASC 842 Leases. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated interim financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and cash flows for the nine months ended September 30, 2021 and 2020. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results for the year ending December 31, 2021, or for any future period. Principles of Consolidation The accompanying unaudited condensed consolidated financial statements of the Company include the accounts of its wholly owned subsidiaries, IMARA Security Corporation and IMARA E.U. Limited. All intercompany transactions and balances have been eliminated in consolidation. IMARA E.U. Limited was dissolved in July 2021 and the dissolution of the subsidiary did not have any material accounting implications on the Company’s unaudited condensed consolidated financial statements as of and for the three and nine months ended September 30, 2021. Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the accompanying unaudited condensed consolidated financial statements are described in the Company’s audited consolidated financial statements for the year ended December 31, 2020 included in the Company’s Annual Report. There have been no material changes in the Company’s significant accounting policies during the three and nine months ended September 30, 2021, with the exception of the modified retrospective adoption of ASC 842 Leases. Use of Estimates The preparation of unaudited condensed consolidated 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 unaudited condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, accrued research and development expenses, stock-based compensation expense, the fair value of the common stock and the intrinsic value of the beneficial conversation feature present in the second tranche of the Series B Preferred Stock issued in February of 2020. Actual results could differ materially from those estimates. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company’s leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, ASU No. 2018-10, Codification Improvements to Topic 842, Leases, ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, ASU No. 2018-20, Narrow-Scope Improvement for Lessors, and ASU No. 2019-01, Leases (Topic 842): Codification Improvements. The Company early adopted these amendments with ASU 2016-02 (collectively, the “new leasing standards”), effective January 1, 2021. The Company adopted the new leasing standards using the modified retrospective transition approach, with no restatement of prior periods and there was no cumulative adjustment to retained earnings. Upon adoption, the Company elected the package of transition practical expedients, which allowed the Company to not reassess the following: (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases and (iii) the treatment of initial direct costs for existing leases. The Company made an accounting policy election to not recognize short-term leases with an initial term of twelve months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations over the lease term. Upon adopting the new leasing standards, the Company recognized an operating lease right-of-use asset of $0.7 million and a corresponding current and non-current operating lease liability of $0.3 million and $0.6 million, respectively, which are included in its consolidated balance sheets. The adoption of the new leasing standards did not have a material impact on the Company’s consolidated statements of operations. The Company determines if an arrangement is a lease at contract inception. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating right-of-use assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable, based upon the information available at the commencement date in determining the present value of the lease payments. The incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The lease payments used to determine operating lease right-of-use assets may include lease incentives and stated rent increases. The Company’s lease agreements may include both lease and non-lease components, which the Company accounts for as a single lease component when the payments are fixed, for all classes of underlying assets. Variable payments included in the lease agreement are expensed as incurred. The Company’s operating leases are reflected in operating lease right-of-use assets and in current operating lease liabilities and long-term operating lease liabilities in its consolidated balance sheets. The Company’s operating lease right-of-use asset as of September 30, 2021 did not include any material lease incentives. Lease expense for future lease payments is recognized on a straight-line basis over the lease term. Prior to the adoption of the new leasing standards, the Company recognized lease costs on a straight-line basis once it gained control of the space, without regard to deferred payment terms, such as rent holidays, that would defer the commencement date of required payments or escalating payment amounts. Any lease incentives received were treated as a reduction of costs over the term of the lease agreement, as they were considered an inseparable part of the lease agreement. The difference between required lease payments and rent expense was recorded as deferred rent, which was reflected as deferred rent in the December 31, 2020 consolidated balance sheet. Segments Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. All of the Company’s long-lived assets are held in the United States. Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity issuances as deferred offering costs until such equity issuances are consummated. After consummation of the equity issuance, these costs are recorded as a reduction in the capitalized amount associated with the equity issuance. Should the equity issuance be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the unaudited condensed consolidated statement of operations and comprehensive loss. There were no deferred offering costs as of September 30, 2021 and December 31, 2020 . Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. The Company’s comprehensive loss includes unrealized losses on available-for-sale debt securities for the three and nine months ended September 30, 2021 and 2020. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASU 2016-02 supersedes the previous leases standard, ASC 840, Leases. For additional information on the adoption of the new leasing standards, please read the Company’s policy above entitled Leases, and Note 7, Commitments and Contingencies, to these condensed consolidated financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I applies to entities that issue financial instruments such as warrants, convertible debt or convertible preferred stock that contain down-round features. Part II replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within ASC Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. For public entities, the amendments in Part I of this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. For all other entities, the amendments in Part I of this update are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted for all entities, including adoption in an interim period. The adoption had no material impact on the Company’s financial position, results of operations or cash flows. The amendments in Part II of this update do not require In March 2020, the FASB issued “ASU 2020-03”, Codification Improvements to Financial Instruments, (“ASU 2020-03”) which addressed, among other topics, Amendments related to ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13”). The amendments align the contractual term under Topic 326 and Topic 842 (Leases) to be consistent, and also clarifies when an entity should record an allowance for credit losses in accordance with Topic 326. For public business entities that meet the definition of a SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, the standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, the standard is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of this new guidance on the Company’s consolidated financial statements and related disclosures, but does not expect the adoption of ASU 2020-03 or ASU 2016-13 to be material.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	3. Fair Value of Financial Assets and Liabilities The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): September 30, 2021 Quoted Active for Assets Significant Observable Inputs Significant Observable Inputs Description Total (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 64,223 $ 64,223 $ — $ — Marketable securities: Corporate debt securities 4,501 — 4,501 — Commercial paper 23,043 — 23,043 — Total financial assets $ 91,767 $ 64,223 $ 27,544 $ — December 31, 2020 Quoted Active for Assets Significant Observable Inputs Significant Observable Inputs Description Total (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 41,208 $ 41,208 $ — $ — Marketable securities: Corporate debt securities 14,807 — 14,807 — Commercial paper 25,717 — 25,717 — Total financial assets $ 81,732 $ 41,208 $ 40,524 $ — As of September 30, 2021 and December 31, 2020, the Company’s Level 1 financial assets consisted of cash equivalents held in money market funds, which are valued using quoted market prices in active markets without any valuation adjustment. The financial assets valued based on Level 2 inputs consist of corporate debt securities and commercial paper, which consist of investments in highly-rated investment-grade securities. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by its third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances. During the three and nine months ended September 30, 2021 and the year ended December 31, 2020, there were no transfers between fair value measurement levels. The carrying values of other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities.

Investments

Investments	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Investments	4. Investments As of September 30, 2021 and December 31, 2020, the Company had short-term investments consisting of corporate debt securities and commercial paper, which are considered to be available-for-sale investments. These are included in short-term investments on the condensed consolidated balance sheets, even though the stated maturity date may be one year or more beyond the current balance sheet date, as the Company views those securities as available for use in current operations, if needed. The following table summarizes the Company’s investments (in thousands): September 30, 2021 Amortized Gross Gains Gross Loss Fair Current: Commercial paper $ 23,043 $ — $ — $ 23,043 Corporate debt securities 4,503 — (2 ) $ 4,501 Total $ 27,546 $ — $ (2 ) $ 27,544 December 31, 2020 Amortized Gross Gains Gross Loss Fair Current: Commercial paper $ 25,716 $ 1 $ — $ 25,717 Corporate debt securities 14,804 3 — 14,807 Total $ 40,520 $ 4 $ — $ 40,524 As of September 30, 2021, the Company held two available-for-sale securities with an aggregate value of approximately $4.5 million in an unrealized loss position for less than twelve months. As of December 31, 2020, the Company had no available-for-sale securities in unrealized loss positions. The Company has the intent and ability to hold such securities until recovery. The Company determined that there was no material change in the credit risk of these investments

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following (in thousands): September 30, 2021 December 31, 2020 Accrued research and development expenses $ 2,599 $ 2,732 Accrued compensation and benefits 1,564 1,090 Accrued professional services 272 355 Accrued other 27 99 Total accrued expenses $ 4,462 $ 4,276

License Agreements

License Agreements	9 Months Ended
	Sep. 30, 2021
License Agreements [Abstract]
License Agreements	6. License Agreements Agreement with Lundbeck In April 2016, the Company entered into a license agreement with Lundbeck A/S (“Lundbeck” and the “Lundbeck Agreement”) pursuant to which Lundbeck granted the Company the following licenses within the field of prevention, treatment or diagnosis of hemoglobinopathy disorders and/or other diseases or disorders, including those directly or indirectly related to hemoglobinopathies: (1) an exclusive, royalty-bearing license to certain patent rights and certain know-how owned or otherwise controlled by Lundbeck (“Licensed Technology”) to research, develop, make, use, sell, and commercialize products (“Licensed Products”) from PDE9 inhibitors, which included tovinontrine (“Licensed Compounds”); (2) a non-exclusive license to the Licensed Technology to make, research, develop, and use such Licensed Technology to enable research and development, with certain restrictions; and (3) a sublicensing right that allows the Company to grant sublicenses to third parties to use the Licensed Technology subject to the certain terms detailed in the Lundbeck Agreement. Under the Lundbeck Agreement, the Company is subject to certain achievement dates for development milestones as defined in the agreement. The regulatory milestones due under the Lundbeck Agreement depend on the products being developed. Development milestones due under the Lundbeck Agreement with respect to the Licensed Compounds total up to $23.5 million, and, for any products that contain PDE9 inhibitors other than Licensed Compounds, total up to $11.8 million. The Company also agreed to pay tiered royalties based on net sales of all products licensed under the agreement in the low single-digit percentages. To date, pursuant to the Lundbeck Agreement, the Company has made cash payments to Lundbeck of $1.8 million consisting of an upfront payment and ongoing milestone payments, which were recorded as research and development expenses. No payments were made during the year ended December 31, 2020, or for the three and nine months ended September 30, 2021. As partial consideration for the license, the Company issued 167,523 shares of common stock to Lundbeck, which represented 8.0% of the Company’s then outstanding equity pursuant to a restricted stock agreement. The shares were fully vested on the date of issuance. The Company also allowed Lundbeck to participate in the fourth tranche of its Series A preferred stock financing in November 2018 at $1.00 per share. The Lundbeck Agreement can be terminated by the Company at any time with 180 days’ written notice. The Company or Lundbeck may terminate the agreement by written notice within a specified period of time in the event of a material breach.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Lease Agreements In 2016, the Company entered into an agreement for office space located in Cambridge, Massachusetts, which was a month-to-month lease. The agreement for this space terminated on August 17, 2019. In May 2019, the Company entered into a new operating lease agreement (the “May 2019 Lease Agreement”) for office space totaling 4,210 square feet, located in Boston, Massachusetts with a 62-month term. The lease includes a rent escalation clause which results in cash rental payments of approximately $0.3 million annually. Rent expense is being recognized on a straight-line basis over the lease term. In addition to the base rent, the Company is also responsible for its share of operating expenses, electricity and real estate taxes, in accordance with the terms of the May 2019 Lease Agreement. The Company provided a security deposit of approximately $0.1 million in May 2019, which is included as a component of other assets on the Company’s unaudited condensed consolidated balance sheets as of September 30, 2021 and December 31, 2020. The Company occupied the space in August 2019 and commenced recognition of rent expense. The Company recorded rent expense of less than $0.1 million during the three months ended September 30, 2021, and approximately $0.2 million during the nine months ended September 30, 2021. In June 2021, the Company entered into an amendment to the May 2019 Lease Agreement (the “June 2021 Amended Lease Agreement”). Under the terms of the June 2021 Amended Lease Agreement, the Company will expand its current premises in Boston, Massachusetts by an additional 5,026 square feet, bringing the total office space to 9,236 square feet. The term of the June 2021 Amended Lease Agreement commences upon completion of the buildout of the additional space, which is expected to be on or about January 1, 2022 and expires on March 31, 2027. The Company has the option to extend the term for one additional five-year The following table summarizes the future lease payments due under the May 2019 Lease Agreement only, as the term of the June 2021 Amended Lease Agreement has not yet commenced (in thousands): September 30, 2021 2021 $ 69 2022 278 2023 284 2024 229 Total Lease Payments $ 860 Less Imputed Interest (144 ) Present value of operating lease liabilities $ 716 Operating cash flows used for operating leases $ 203 Weighted-average remaining lease term (years) 3.08 Weighted-average discount rate 8 % Under the prior lease accounting guidance, minimum rental commitments under non-cancelable leases as of December 31, 2020 were as follows (in thousands): Minimum Lease Payments 2021 273 2022 278 2023 284 2024 229 $ 1,064 Legal Proceedings The Company may from time to time be party to litigation arising in the ordinary course of business. The Company was not subject to any material legal proceedings during the three and nine months ended September 30, 2021 and year ended December 31, 2020, and no material legal proceedings are currently pending or, to the best of its knowledge, threatened. Indemnification Obligations The Company agrees to standard indemnification obligations as part of entering into agreements in the ordinary course of business. Pursuant to the indemnification provisions, the Company agrees to indemnify, hold harmless, and to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company’s business partners, in connection with matters specified in the applicable provision, which may include any U.S. patent or any copyright or other intellectual property infringement claim by any third-party with respect to the Company’s products or product liability claims by any third-party with respect to the Company’s products. The term of these indemnification obligations is generally perpetual any time after execution of the agreement. The potential amount of future payments the Company could be required to make under these indemnification obligations is unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification obligations.

Convertible Preferred Stock

Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2021
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	8. Convertible Preferred Stock Prior to the sale of common stock in connection with its IPO, the Company had funded its operations primarily with proceeds from the sale of Preferred Stock. On February 25, 2020, the Company raised $17.1 million in net proceeds from the sale of 1,562,994‬ shares of Series B Preferred Stock, at a price of $10.9722 per share, upon a waiver of specified milestone conditions from the holders of a majority of the shares then held by the holders of Series B Preferred Stock. Upon issuance, each share of Series B Preferred Stock included an embedded beneficial conversion feature as the estimated fair value of the Company’s common stock on the date of issuance of the Series B Preferred Stock was higher than the effective conversion price of the Series B Preferred Stock of $10.9722 per share. Given the proximity of the issuance to the Company’s public offering, the Company utilized the $16.00 public offering price of its common stock Upon the completion of the IPO on March 16, 2020, all 70,378,661 shares of outstanding preferred stock automatically converted into 11,172,955 shares of common stock. Prior to the conversion, the holders of the preferred stock were entitled to receive noncumulative dividends of 8% per annum of the Series B issuance price only when and if declared by the Company’s board of directors. No dividends have been declared by the Company’s board of directors since inception.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity On August 13, 2019, the Company’s board of directors, and on February 26, 2020, the Company’s stockholders, approved the Company’s restated certificate of incorporation, which became effective upon closing of the IPO on March 16, 2020, to authorize Common stockholders are entitled to receive dividends, as may be declared by the Board, if any, subject to the preferential dividend rights of any preferred stock then outstanding. Through September 30, 2021, no cash dividends have been declared or paid. As of September 30, 2021, 10,000,000 shares of preferred stock were authorized and no shares of preferred stock were issued or outstanding. As of September 30, 2021 and December 31, 2020, the Company has reserved for future issuance the following shares of common stock: September 30, 2021 December 31, 2020 Shares reserved for future issuance under the 2020 Equity Incentive Plan 1,276,472 1,110,675 Shares reserved for future issuance under the 2020 Employee Stock Purchase Plan 187,209 191,363 1,463,681 1,302,038

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Compensation Related Costs [Abstract]
Stock-Based Compensation	10. Stock-Based Compensation 2016 Stock Incentive Plan The Company’s 2016 Stock Incentive Plan, (the “2016 Plan”) provided for the grant of restricted stock, restricted stock units, stock appreciation rights, incentive stock options, non-statutory stock options and other stock-based awards to employees, officers, members of the Board, consultants and advisors of the Company. As of the effective date of the 2020 Equity Incentive Plan (the “2020 Plan”) on March 11, 2020, and as of September 30, 2021, no shares remained available for future issuance under the 2016 Plan. Any options or awards outstanding under the 2016 Plan remain outstanding and effective. 2020 Equity Incentive Plan On October 1, 2019, the Company’s board of directors adopted, and on February 26, 2020 the Company’s stockholders approved, the 2020 Plan, which became effective on March 11, 2020. The 2020 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares reserved for issuance under the 2020 Plan is the sum of: (1) 1,220,283 shares of the Company’s common stock; plus (2) the number of shares (up to a maximum of 2,091,969 shares) equal to the sum of (x) 228,852 shares, which represents the Company’s common stock reserved for issuance under the 2016 Plan that remained available for grant under the 2016 Plan as of March 11, 2020 and (y) the number of shares of the Company’s common stock subject to outstanding awards granted under the 2016 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right. The number of shares reserved will be annually increased on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2021 and continuing until, and including, the fiscal year ending December 31, 2030, equal to the lesser of (i) 4% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors. On January 1, 2021, 701,930 additional shares were reserved for issuance under the 2020 Plan pursuant to this provision. No more than 8,541,982 shares of common stock may be issued as incentive stock options under the 2020 Plan. The shares of common stock underlying any awards that expire, terminate, or are otherwise surrendered, cancelled, forfeited or repurchased by the Company under the 2016 Plan or the 2020 Plan will be added back to the shares of common stock available for issuance under the 2020 Plan. As of September 30, 2021, there were 1,276,472 shares available for future issuance under the 2020 Plan. For financial reporting purposes, the Company performed common stock valuations with the assistance of a third-party specialist through October 23, 2019 to determine stock-based compensation expense for stock options. Upon completion of the IPO, the fair value of the common stock on the grant date was based on the closing price of the stock on the Nasdaq Global Select Market on the date of grant. The following table summarizes the Company’s stock option activity: Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2020 1,935,632 $ 9.85 8.14 $ 24,260 Granted 862,953 10.87 Exercised (158,681 ) 4.34 Forfeited (326,820 ) 14.75 Outstanding as of September 30, 2021 2,313,084 $ 9.92 8.39 $ 254 Options vested and exercisable as of September 30, 2021 764,726 $ 6.10 7.44 $ 206 The aggregate intrinsic value of 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 common stock as of the end of the period. The weighted-average grant date fair value of the Company’s stock options granted during the three and nine months ended September 30, 2021 was $3.66 and $7.44, respectively. The weighted-average grant date fair value of the Company’s stock options granted during each of the three and nine months ended September 30, 2020 was $12.99 and $11.30, respectively. Performance-based awards The Company granted stock options to purchase an aggregate of 220,928 shares of common stock to certain employees, officers and consultants and advisors of the Company on May 16, 2019, June 5, 2019 and September 21, 2019, which contained performance-based vesting criteria. Vesting of these options was contingent on the closing of the second tranche of Series B Preferred Stock financing. Stock-based compensation expense associated with performance-based stock options is recognized if the performance conditions are considered probable of being achieved, using management’s best estimates. As a result of the performance condition being met on February 25, 2020, these options vested as to 25% of the shares underlying each option on February 25, 2021 and will vest as to the remainder of the shares in equal quarterly installments for three years thereafter. The Company recognized stock-based compensation expense of less than $0.1 million and $0.1 million for these options during the three and nine months ended September 30, 2021, respectively. Stock-Based Compensation Stock-based compensation expense included in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 322 $ 161 $ 1,034 $ 501 General and administrative 681 481 1,833 1,051 Total stock-based compensation expense $ 1,003 $ 642 $ 2,867 $ 1,552 As of September 30, 2021 and December 31, 2020, total unrecognized compensation cost related to the unvested stock-based awards was $10.3 million and $9.5 million, respectively, which is expected to be recognized over a weighted-average period of 2.79 and 3.22 years, respectively. 2020 Employee Stock Purchase Plan On October 1, 2019, the Company’s board of directors adopted, and on February 26, 2020, the Company’s stockholders approved the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which became effective on March 11, 2020. The 2020 ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 193,216 shares of the Company’s common stock. The number of shares of the Company’s common stock reserved for issuance under the 2020 ESPP will automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021 and continuing until, and including, the fiscal year commencing on January 1, 2031, in an amount equal to the lowest of ( i ) 386,432 shares of the Company’s common stock, (ii) 1 % of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (iii) an amount determined by the Company’s board of directors . The Company’s board of directors decided not to increase the number of shares of the Company’s common stock reserved for issuance under the 2020 ESPP for the 2021 fiscal year. During the nine months ended September 30, 2021, $0.1 million was withheld from employees, on an after-tax basis, in order to purchase 4,154 shares of the Company’s common stock. No shares were purchased during the three months ended September 30, 2021. The Company recorded stock-based compensation expense related to the 2020 ESPP of less than $0.1 million. As of September 30, 2021, 187,209 shares of the Company’s common stock remained available for issuance under the 2020 ESPP. As of September 30, 2021, there was less than $0.1 million of total unrecognized stock-based compensation expense related to the ESPP. The expense is expected to be recognized over a period of 2.5 months.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets. On March 27, 2020, the United States enacted the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”). The Cares Act includes provisions relating to refundable payroll tax credits, deferment of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act also established a Paycheck Protection Program whereby certain small businesses are eligible for a loan to fund payroll expenses, rent, and related costs. The CARES Act provided for an Employee Retention Credit (“ERC”), which is a refundable payroll tax credit that encouraged businesses to keep employees on the payroll during the COVID-19 pandemic. Eligible employers could qualify for up to $5,000 of credit for each employee based on certain wages paid after March 12, 2020 and before January 1, 2021. The ERC was subsequently amended by the Consolidated Appropriation Act (“CAA”) of 2021 and the American Rescue Plan Act (“ARPA”) of 2021. Under CAA and ARPA amendments, employers can claim a refundable tax credit against the employer share of social security tax equal to 70% of the qualified wages (including certain health care expenses) paid to employees after December 31, 2020 through December 31, 2021. Qualified wages are limited to $10,000 per employee per calendar quarter in 2021 so the maximum ERTC available is $7,000 per employee per calendar quarter. Based on the Company’s evaluation of this provision and pandemic-related impact on its operations in 2020 and 2021, it was determined that the Company qualified to claim ERC in the second, third and fourth calendar quarters of 2020, as well as in both the first, second, and third calendar quarters of 2021. The Company recognized an ERC of approximately $0.3 million and $1.0 million as an offset to payroll tax expenses for the three and nine months ended September 30, 2021, respectively, in its consolidated statements of operations. The Company will continue to assess its eligibility to claim ERC for the fourth quarter of 2021.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	12. Net Loss Per Share Basic and diluted net loss per share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period. In 2020, the net loss applicable to common stockholders did not equal net loss due to the accretion of the beneficial conversion feature of Series B Preferred Stock in the amount of $7.9 million. The beneficial conversion feature was initially recorded as a discount on the Series B Preferred Stock with a corresponding amount recorded to Additional Paid-in Capital. The discount on the Series B Preferred Stock was then immediately written off as a deemed dividend as the Series B Preferred Stock does not have a stated redemption date and is immediately convertible at the option of the holder. The Company has computed diluted net loss per common share after giving consideration to all potentially dilutive common shares, including convertible preferred stock and options to purchase common stock during the period determined using the if-converted method, except where the effect of including such securities would be antidilutive. Because the Company has reported net losses since inception, these potential common shares have been anti-dilutive and basic and diluted loss per share have been the same. The Company excluded the following potential common shares from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common stock 2,313,084 1,938,005 2,313,084 1,938,005 Shares reserved for future issuance under the ESPP 187,209 — 187,209 —

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	13. Related Party Transactions Lundbeck Lundbeckfond Invest A/S is one of the Company’s stockholders and participated in all tranches of the Series A preferred stock financing and both tranches of the Series B preferred stock financing. Prior to the conversion of the Company’s preferred stock, Lundbeckfond Invest A/S owned 5,470,492 shares of Series A Preferred Stock as of December 31, 2019, and 478,749 shares of Series Seed Preferred Stock as of December 31, 2019. Lundbeckfond Invest A/S owned 1,326,111 shares of Series B Preferred Stock as of December 31, 2019. All shares of preferred stock converted into shares of common stock upon closing of the IPO. Lundbeckfond Invest A/S also purchased 187,500 shares of common stock in the IPO. This reflects a 5.0% and a 7.4% ownership interest on a fully diluted basis as of September 30, 2021 and December 31, 2020, respectively. Mette Kirstine Agger, who was a member of our board of directors until June 29, 2021, is a Managing Partner at Lundbeckfonden Ventures, which is an affiliate of Lundbeckfond Invest A/S. Lundbeck, an affiliate of Lundbeckfond Invest A/S, is also one of the Company’s stockholders and participated in the fourth tranche of the Company’s Series A preferred stock financing. Prior to the conversion of the Company’s preferred stock, Lundbeck owned 499,069 shares of Series A Preferred Stock as of December 31, 2019, as well as 443,271 shares of common stock issued in conjunction with the Lundbeck Agreement (See Note 6). All shares of preferred stock converted into shares of common stock upon closing of the IPO. This reflects a 1.8% and a 2.7% ownership interest on a fully diluted basis as of September 30, 2021 and December 31, 2020, respectively. Lundbeck did not participate in the Series B Preferred Stock financing. To date, pursuant to the Lundbeck Agreement, the Company has made cash payments to Lundbeck of $1.8 million consisting of an upfront payment and ongoing milestone payments which are recorded as research and development expense.

Benefit Plans

Benefit Plans	9 Months Ended
	Sep. 30, 2021
Compensation And Retirement Disclosure [Abstract]
Benefit Plans	14. Benefit Plans The Company established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code effective as of January 2019. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Matching contributions to the plan may be made at the discretion of the Board. The Company has made $0.1 million of contributions to the plan to date.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). 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 as amended by Accounting Standards Updates of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s Annual Report on Form 10-K (the “Annual Report”), filed with the SEC on March 5, 2021. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the audited financial statements, with the exception of the modified retrospective adoption of ASC 842 Leases. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated interim financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and cash flows for the nine months ended September 30, 2021 and 2020. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results for the year ending December 31, 2021, or for any future period.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements of the Company include the accounts of its wholly owned subsidiaries, IMARA Security Corporation and IMARA E.U. Limited. All intercompany transactions and balances have been eliminated in consolidation. IMARA E.U. Limited was dissolved in July 2021 and the dissolution of the subsidiary did not have any material accounting implications on the Company’s unaudited condensed consolidated financial statements as of and for the three and nine months ended September 30, 2021.
Use of Estimates	Use of Estimates The preparation of unaudited condensed consolidated 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 unaudited condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, accrued research and development expenses, stock-based compensation expense, the fair value of the common stock and the intrinsic value of the beneficial conversation feature present in the second tranche of the Series B Preferred Stock issued in February of 2020. Actual results could differ materially from those estimates.
Leases	Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company’s leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, ASU No. 2018-10, Codification Improvements to Topic 842, Leases, ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, ASU No. 2018-20, Narrow-Scope Improvement for Lessors, and ASU No. 2019-01, Leases (Topic 842): Codification Improvements. The Company early adopted these amendments with ASU 2016-02 (collectively, the “new leasing standards”), effective January 1, 2021. The Company adopted the new leasing standards using the modified retrospective transition approach, with no restatement of prior periods and there was no cumulative adjustment to retained earnings. Upon adoption, the Company elected the package of transition practical expedients, which allowed the Company to not reassess the following: (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases and (iii) the treatment of initial direct costs for existing leases. The Company made an accounting policy election to not recognize short-term leases with an initial term of twelve months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations over the lease term. Upon adopting the new leasing standards, the Company recognized an operating lease right-of-use asset of $0.7 million and a corresponding current and non-current operating lease liability of $0.3 million and $0.6 million, respectively, which are included in its consolidated balance sheets. The adoption of the new leasing standards did not have a material impact on the Company’s consolidated statements of operations. The Company determines if an arrangement is a lease at contract inception. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent its obligation to make lease payments arising from the lease. Operating right-of-use assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The Company uses the implicit rate when readily determinable and uses its incremental borrowing rate when the implicit rate is not readily determinable, based upon the information available at the commencement date in determining the present value of the lease payments. The incremental borrowing rate is determined using a secured borrowing rate for the same currency and term as the associated lease. The lease payments used to determine operating lease right-of-use assets may include lease incentives and stated rent increases. The Company’s lease agreements may include both lease and non-lease components, which the Company accounts for as a single lease component when the payments are fixed, for all classes of underlying assets. Variable payments included in the lease agreement are expensed as incurred. The Company’s operating leases are reflected in operating lease right-of-use assets and in current operating lease liabilities and long-term operating lease liabilities in its consolidated balance sheets. The Company’s operating lease right-of-use asset as of September 30, 2021 did not include any material lease incentives. Lease expense for future lease payments is recognized on a straight-line basis over the lease term. Prior to the adoption of the new leasing standards, the Company recognized lease costs on a straight-line basis once it gained control of the space, without regard to deferred payment terms, such as rent holidays, that would defer the commencement date of required payments or escalating payment amounts. Any lease incentives received were treated as a reduction of costs over the term of the lease agreement, as they were considered an inseparable part of the lease agreement. The difference between required lease payments and rent expense was recorded as deferred rent, which was reflected as deferred rent in the December 31, 2020 consolidated balance sheet.
Segments	Segments Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. All of the Company’s long-lived assets are held in the United States.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity issuances as deferred offering costs until such equity issuances are consummated. After consummation of the equity issuance, these costs are recorded as a reduction in the capitalized amount associated with the equity issuance. Should the equity issuance be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the unaudited condensed consolidated statement of operations and comprehensive loss. There were no deferred offering costs as of September 30, 2021 and December 31, 2020 .
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. The Company’s comprehensive loss includes unrealized losses on available-for-sale debt securities for the three and nine months ended September 30, 2021 and 2020.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASU 2016-02 supersedes the previous leases standard, ASC 840, Leases. For additional information on the adoption of the new leasing standards, please read the Company’s policy above entitled Leases, and Note 7, Commitments and Contingencies, to these condensed consolidated financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I applies to entities that issue financial instruments such as warrants, convertible debt or convertible preferred stock that contain down-round features. Part II replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within ASC Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. For public entities, the amendments in Part I of this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. For all other entities, the amendments in Part I of this update are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted for all entities, including adoption in an interim period. The adoption had no material impact on the Company’s financial position, results of operations or cash flows. The amendments in Part II of this update do not require In March 2020, the FASB issued “ASU 2020-03”, Codification Improvements to Financial Instruments, (“ASU 2020-03”) which addressed, among other topics, Amendments related to ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13”). The amendments align the contractual term under Topic 326 and Topic 842 (Leases) to be consistent, and also clarifies when an entity should record an allowance for credit losses in accordance with Topic 326. For public business entities that meet the definition of a SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, the standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For all other entities, the standard is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of this new guidance on the Company’s consolidated financial statements and related disclosures, but does not expect the adoption of ASU 2020-03 or ASU 2016-13 to be material.

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands): September 30, 2021 Quoted Active for Assets Significant Observable Inputs Significant Observable Inputs Description Total (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 64,223 $ 64,223 $ — $ — Marketable securities: Corporate debt securities 4,501 — 4,501 — Commercial paper 23,043 — 23,043 — Total financial assets $ 91,767 $ 64,223 $ 27,544 $ — December 31, 2020 Quoted Active for Assets Significant Observable Inputs Significant Observable Inputs Description Total (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 41,208 $ 41,208 $ — $ — Marketable securities: Corporate debt securities 14,807 — 14,807 — Commercial paper 25,717 — 25,717 — Total financial assets $ 81,732 $ 41,208 $ 40,524 $ —

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Summary of Investments	The following table summarizes the Company’s investments (in thousands): September 30, 2021 Amortized Gross Gains Gross Loss Fair Current: Commercial paper $ 23,043 $ — $ — $ 23,043 Corporate debt securities 4,503 — (2 ) $ 4,501 Total $ 27,546 $ — $ (2 ) $ 27,544 December 31, 2020 Amortized Gross Gains Gross Loss Fair Current: Commercial paper $ 25,716 $ 1 $ — $ 25,717 Corporate debt securities 14,804 3 — 14,807 Total $ 40,520 $ 4 $ — $ 40,524

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): September 30, 2021 December 31, 2020 Accrued research and development expenses $ 2,599 $ 2,732 Accrued compensation and benefits 1,564 1,090 Accrued professional services 272 355 Accrued other 27 99 Total accrued expenses $ 4,462 $ 4,276

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Summary of Future Lease Payments	The following table summarizes the future lease payments due under the May 2019 Lease Agreement only, as the term of the June 2021 Amended Lease Agreement has not yet commenced (in thousands): September 30, 2021 2021 $ 69 2022 278 2023 284 2024 229 Total Lease Payments $ 860 Less Imputed Interest (144 ) Present value of operating lease liabilities $ 716 Operating cash flows used for operating leases $ 203 Weighted-average remaining lease term (years) 3.08 Weighted-average discount rate 8 %
Summary of Minimum Rental Payments Under Non-Cancelable Leases	Under the prior lease accounting guidance, minimum rental commitments under non-cancelable leases as of December 31, 2020 were as follows (in thousands): Minimum Lease Payments 2021 273 2022 278 2023 284 2024 229 $ 1,064

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Schedule of Shares Reserved for Future Issuance	As of September 30, 2021 and December 31, 2020, the Company has reserved for future issuance the following shares of common stock: September 30, 2021 December 31, 2020 Shares reserved for future issuance under the 2020 Equity Incentive Plan 1,276,472 1,110,675 Shares reserved for future issuance under the 2020 Employee Stock Purchase Plan 187,209 191,363 1,463,681 1,302,038

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Compensation Related Costs [Abstract]
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity: Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding as of December 31, 2020 1,935,632 $ 9.85 8.14 $ 24,260 Granted 862,953 10.87 Exercised (158,681 ) 4.34 Forfeited (326,820 ) 14.75 Outstanding as of September 30, 2021 2,313,084 $ 9.92 8.39 $ 254 Options vested and exercisable as of September 30, 2021 764,726 $ 6.10 7.44 $ 206
Summary of Stock-Based Compensation Expense	Stock-based compensation expense included in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 322 $ 161 $ 1,034 $ 501 General and administrative 681 481 1,833 1,051 Total stock-based compensation expense $ 1,003 $ 642 $ 2,867 $ 1,552

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Anti Dilutive Potential Common Shares Excluded From Computation of Diluted Net Loss Per Share	The Company excluded the following potential common shares from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common stock 2,313,084 1,938,005 2,313,084 1,938,005 Shares reserved for future issuance under the ESPP 187,209 — 187,209 —

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) $ / shares in Units, $ in Thousands	Jul. 16, 2021USD ($)$ / sharesshares	Apr. 01, 2021USD ($)shares	Apr. 13, 2020USD ($)shares	Mar. 16, 2020USD ($)$ / sharesshares	Feb. 25, 2020USD ($)$ / sharesshares	Feb. 29, 2020	Jun. 30, 2021USD ($)	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)shares
Nature Of Business [Line Items]
Reverse stock split								1-for-6.299
Reverse stock splits, conversion ratio						0.159
Preferred stock, per share | $ / shares	$ 6
Proceeds from issuance of Series B convertible preferred stock, net of issuance costs									$ 17,150
ATM offering stock issuance costs							$ 357
Common stock issued and sold | shares	8,333,333
Gross proceeds from initial public offering				$ 75,200					$ 80,427
Aggregate gross proceeds of common stock issued and sold			$ 11,300
Underwriting discounts and commissions and offering expenses								$ 10,000
Conversion of outstanding preferred stock | shares				70,378,661
Common stock issued upon conversion | shares				11,172,955
Common stock, shares issued | shares								26,275,722		17,548,263
Net proceeds from issuance of common stock	$ 46,800
Cash, cash equivalents, and investments								$ 102,800
Accumulated deficit								133,178		$ 96,113
IPO
Nature Of Business [Line Items]
Preferred stock, per share | $ / shares				$ 16
Common stock issued and sold | shares			705,000	4,700,000
Net proceeds after deducting underwriting discounts and commissions and offering expenses								$ 76,500
Conversion of outstanding preferred stock | shares				70,378,661
At The Market Offering
Nature Of Business [Line Items]
Common stock, shares issued | shares								231,291
Net proceeds from issuance of common stock								$ 1,500
Maximum
Nature Of Business [Line Items]
Common stock issued and sold | shares		200,000,000
Aggregate gross proceeds of common stock issued and sold		$ 75,000
Series B Preferred Stock | Second Tranche
Nature Of Business [Line Items]
Preferred shares, issued | shares					1,562,994
Preferred stock, per share | $ / shares					$ 10.9722
Proceeds from issuance of Series B convertible preferred stock, net of issuance costs					$ 17,100
Series B Preferred Stock | Second Tranche | Maximum
Nature Of Business [Line Items]
ATM offering stock issuance costs					$ 100

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)Segment
Summary Of Significant Accounting Policies [Line Items]
Right of use assets - operating leases	$ 580
Operating lease liability, current	250
Operating lease liability, non-current	$ 466
Number of operating segments | Segment	1
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Right of use assets - operating leases	$ 700
Operating lease liability, current	300
Operating lease liability, non-current	$ 600

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets:
Marketable securities	$ 27,544	$ 40,524
Fair Value Measurements Recurring
Assets:
Total financial assets	91,767	81,732
Fair Value Measurements Recurring | Money Market Funds
Assets:
Cash and cash equivalents	64,223	41,208
Fair Value Measurements Recurring | Corporate Debt Securities
Assets:
Marketable securities	4,501	14,807
Fair Value Measurements Recurring | Commercial Paper
Assets:
Marketable securities	23,043	25,717
Fair Value Measurements Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total financial assets	64,223	41,208
Fair Value Measurements Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Assets:
Cash and cash equivalents	64,223	41,208
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Total financial assets	27,544	40,524
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2) | Corporate Debt Securities
Assets:
Marketable securities	4,501	14,807
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2) | Commercial Paper
Assets:
Marketable securities	$ 23,043	$ 25,717

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value, assets, Level 1 to Level 2 transfers, amount	$ 0	$ 0	$ 0
Fair value, assets, Level 2 to Level 1 transfers, amount	0	0	0
Fair value, asset transfers Into Level 3	0	0	0
Fair value, asset, transfers out of Level 3	$ 0	$ 0	$ 0

Investments - Summary of Invest

Investments - Summary of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 27,546	$ 40,520
Gross Unrealized Gains		4
Gross Unrealized Loss	(2)
Fair Value	27,544	40,524
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	4,503	14,804
Gross Unrealized Gains		3
Gross Unrealized Loss	(2)
Fair Value	4,501	14,807
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	23,043	25,716
Gross Unrealized Gains		1
Fair Value	$ 23,043	$ 25,717

Investments - Additional Inform

Investments - Additional Information (Details)	Sep. 30, 2021USD ($)Position	Dec. 31, 2020USD ($)
Investments Debt And Equity Securities [Abstract]
Number of available-for-sale securities in unrealized loss positions for less than twelve months | Position	2
Available-for-sale securities in unrealized loss positions for less than twelve months	$ 4,500,000
Available-for-sale securities in unrealized loss positions		$ 0

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued research and development expenses	$ 2,599	$ 2,732
Accrued compensation and benefits	1,564	1,090
Accrued professional services	272	355
Accrued other	27	99
Total accrued expenses	$ 4,462	$ 4,276

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended	51 Months Ended	66 Months Ended
	Apr. 30, 2016	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Sep. 30, 2021	Jul. 16, 2021	Dec. 31, 2019	Nov. 30, 2018
License Agreements [Line Items]
Common stock, shares issued		26,275,722	26,275,722	17,548,263		26,275,722
Public offering price per share							$ 6
Lundbeck Agreement | Lundbeck
License Agreements [Line Items]
Maximum development milestones payments due	$ 23,500,000
Maximum development milestones payments due for other than licensed product	$ 11,800,000
Upfront and ongoing milestone payments		$ 0	$ 0	$ 0
Common stock, shares issued	167,523							443,271
Outstanding equity percentage pursuant to restricted stock agreement	8.00%
Notice period for agreement termination			180 days
Lundbeck Agreement | Lundbeck | Series A Preferred Stock | Fourth Tranche
License Agreements [Line Items]
Public offering price per share									$ 1
Lundbeck Agreement | Lundbeck | Research and Development Expense
License Agreements [Line Items]
Upfront and ongoing milestone payments					$ 1,800,000	$ 1,800,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	9 Months Ended
	Jun. 30, 2021	May 31, 2019	Sep. 30, 2021	Sep. 30, 2021
Commitments and Contingencies [Line Items]
Lease agreements office space termination date				Aug. 17, 2019
Operating lease description				In June 2021, the Company entered into an amendment to the May 2019 Lease Agreement (the “June 2021 Amended Lease Agreement”). Under the terms of the June 2021 Amended Lease Agreement, the Company will expand its current premises in Boston, Massachusetts by an additional 5,026 square feet, bringing the total office space to 9,236 square feet.
Operating lease, payments				$ 203,000
Operating lease, payments			$ 860,000	$ 860,000
May 2019 Lease Agreement
Commitments and Contingencies [Line Items]
Operating lease description				In May 2019, the Company entered into a new operating lease agreement (the “May 2019 Lease Agreement”) for office space totaling 4,210 square feet, located in Boston, Massachusetts with a 62-month term.
Operating lease term of contract		62 months
Operating lease, payments		$ 300,000
Security deposit		$ 100,000
Rent expense				$ 200,000
Additional security deposit	$ 100,000
June 2021 Amended Lease Agreement
Commitments and Contingencies [Line Items]
Operating lease term of contract	12 months
Security deposit	$ 200,000
Rent expense	$ 600,000
Lease expiration date	Mar. 31, 2027
Operating lease renewal term	5 years
Operating lease option to extend	The Company has the option to extend the term for one additional five-year period upon the Company’s written notice to the landlord at least 12 months and no more than 15 months in advance of the extension period.
Operating lease, payments	$ 3,800,000
Maximum | May 2019 Lease Agreement
Commitments and Contingencies [Line Items]
Rent expense			$ 100,000

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Lease Payments (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Lessee Disclosure [Abstract]
2021	$ 69
2022	278
2023	284
2024	229
Total Lease Payments	860
Less Imputed Interest	(144)
Present value of operating lease liabilities	716
Operating cash flows used for operating leases	$ 203
Weighted-average remaining lease term (years)	3 years 29 days
Weighted-average discount rate	8.00%

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Minimum Rental Payments Under Non-Cancelable Leases (Details) $ in Thousands	Dec. 31, 2020USD ($)
Lessee Disclosure [Abstract]
2021	$ 273
2022	278
2023	284
2024	229
Total Minimum Lease Payments	$ 1,064

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($)	Mar. 16, 2020	Feb. 25, 2020	Sep. 30, 2021	Sep. 30, 2020	Jul. 16, 2021
Temporary Equity [Line Items]
Net proceeds from sale				$ 17,150,000
Stock value, per share					$ 6
Conversion of outstanding preferred stock	70,378,661
Common stock issued upon conversion	11,172,955
Dividends			$ 0
IPO
Temporary Equity [Line Items]
Stock value, per share	$ 16
Conversion of outstanding preferred stock	70,378,661
IPO | Common Stock
Temporary Equity [Line Items]
Stock value, per share	$ 16
Common stock issued upon conversion	11,172,955
Series B Preferred Stock
Temporary Equity [Line Items]
Noncumulative dividends percentage	8.00%
Series B Preferred Stock | Second Tranche
Temporary Equity [Line Items]
Net proceeds from sale		$ 17,100,000
Preferred shares, issued		1,562,994
Stock value, per share		$ 10.9722
Intrinsic value of beneficial conversion discount		$ 7,900,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Mar. 16, 2020	Dec. 31, 2019
Equity [Abstract]
Preferred stock, authorized	10,000,000	0	10,000,000
Preferred stock par value per share	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000	200,000,000	100,000,000
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Cash dividends	$ 0
Preferred stock, shares authorized	10,000,000	0	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Shares Reserved for Future Issuance (Details) - shares	Sep. 30, 2021	Dec. 31, 2020	Mar. 11, 2020
Class Of Stock [Line Items]
Shares reserved for future issuance	1,463,681	1,302,038
2020 Equity Incentive Plan
Class Of Stock [Line Items]
Shares reserved for future issuance	1,276,472	1,110,675
2020 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares reserved for future issuance	187,209	191,363	193,216

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	Mar. 11, 2020	Sep. 21, 2019	Jun. 05, 2019	May 16, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remaining available for future issuance					1,463,681		1,463,681		1,302,038
Share-based compensation award, granted							862,953
Share-based compensation award, weighted-average fair value					$ 3.66	$ 12.99	$ 7.44	$ 11.30
Stock-based compensation expense					$ 1,003,000	$ 642,000	$ 2,867,000	$ 1,552,000
Unrecognized stock-based compensation expense					10,300,000		$ 10,300,000		$ 9,500,000
Expected weighted average period to recognize expense							2 years 9 months 14 days		3 years 2 months 19 days
Performance Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation award, granted		220,928	220,928	220,928
Performance Based Awards | Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vested percentage							25.00%
Maximum | Performance Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense					$ 100,000		$ 100,000
2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remaining available for future issuance					0		0
2016 Stock Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remaining available for future issuance					228,852		228,852
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remaining available for future issuance					1,276,472		1,276,472		1,110,675
Number of shares of common stock that may be issued accordance with plan	1,220,283
Description of changes in the number of shares reserved for issuance							The number of shares reserved will be annually increased on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2021 and continuing until, and including, the fiscal year ending December 31, 2030, equal to the lesser of (i) 4% of the number of shares of the Company’s common stock outstanding on the first day of such fiscal year and (ii) an amount determined by the Company’s board of directors.
Common stock outstanding percent	4.00%
2020 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock that may be issued accordance with plan	8,541,982
Number of shares authorized	2,091,969
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remaining available for future issuance	193,216				187,209		187,209		191,363
Number of shares of common stock that may be issued accordance with plan	386,432
Common stock outstanding percent	1.00%
Expected weighted average period to recognize expense	2 months 15 days
Earnings withheld from employees to purchase shares of common stock under purchase plan							$ 100,000
Shares purchased under the ESPP					0		4,154
2020 Employee Stock Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense							$ 100,000
Unrecognized stock-based compensation expense	$ 100,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Compensation Related Costs [Abstract]
Number of Shares, Beginning Balance | shares	1,935,632
Number of Shares, Granted | shares	862,953
Number of Shares, Exercised | shares	(158,681)
Number of Shares, Forfeited | shares	(326,820)
Number of Shares, Ending Balance | shares	2,313,084	1,935,632
Number of Shares, Options vested and exercisable | shares	764,726
Weighted-Average Exercise Price, Beginning Balance | $ / shares	$ 9.85
Weighted-Average Exercise Price, Granted | $ / shares	10.87
Weighted-Average Exercise Price, Exercised | $ / shares	4.34
Weighted-Average Exercise Price, Forfeited | $ / shares	14.75
Weighted-Average Exercise Price, Ending Balance | $ / shares	9.92	$ 9.85
Weighted-Average Exercise Price, Options vested and exercisable | $ / shares	$ 6.10
Weighted-Average Remaining Contractual Term, Outstanding	8 years 4 months 20 days	8 years 1 month 20 days
Weighted-Average Remaining Contractual Term, Options vested and exercisable	7 years 5 months 8 days
Aggregate Intrinsic Value, Balance | $	$ 254	$ 24,260
Aggregate Intrinsic Value, Options vested and exercisable | $	$ 206

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,003	$ 642	$ 2,867	$ 1,552
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	322	161	1,034	501
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 681	$ 481	$ 1,833	$ 1,051

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended	9 Months Ended	10 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2021
Income Tax Contingency [Line Items]
Maximum refundable tax credit allowed per employee			$ 5,000
Qualified wages limit per employee	$ 10,000
Maximum ERTC available per employee	7,000
Employee retention credit as offset to payroll tax expense	$ 300,000	$ 1,000,000
Scenario Forecast
Income Tax Contingency [Line Items]
Percentage of qualified wages				70

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Accretion of Series B convertible preferred stock	$ 7,900	$ 7,858

Net Loss Per Share - Anti Dilut

Net Loss Per Share - Anti Dilutive Potential Common Shares Excluded From Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Shares reserved for future issuance under the ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per common share	187,209		187,209
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per common share	2,313,084	1,938,005	2,313,084	1,938,005

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)

Jul. 16, 2021

Apr. 13, 2020

Mar. 16, 2020

Sep. 30, 2021

Jun. 30, 2020

Mar. 31, 2020

Sep. 30, 2021

Dec. 31, 2020

Jun. 30, 2020

Sep. 30, 2021

Dec. 31, 2019

Apr. 30, 2016

Related Party Transaction [Line Items]

Number of common stock purchased

8,333,333

Common stock, shares issued

26,275,722

26,275,722

17,548,263

26,275,722

IPO

Related Party Transaction [Line Items]

Number of common stock purchased

705,000

4,700,000

IPO | Common Stock

Related Party Transaction [Line Items]

Number of common stock purchased

705,000

4,700,000

Lundbeckfond Invest A/S

Related Party Transaction [Line Items]

Ownership interest percentage

5.00%

5.00%

7.40%

5.00%

Lundbeckfond Invest A/S | IPO | Common Stock

Related Party Transaction [Line Items]

Number of common stock purchased

187,500

Lundbeck | Lundbeck Agreement

Related Party Transaction [Line Items]

Ownership interest percentage

1.80%

1.80%

2.70%

1.80%

Common stock, shares issued

443,271

167,523

Upfront and ongoing milestone payments

$ 0

$ 0

$ 0

Lundbeck | Lundbeck Agreement | Research and Development Expense

Related Party Transaction [Line Items]

Upfront and ongoing milestone payments

$ 1,800,000

$ 1,800,000

Series A Preferred Stock | Lundbeckfond Invest A/S

Related Party Transaction [Line Items]

Shares owned

5,470,492

Series A Preferred Stock | Lundbeck | Lundbeck Agreement

Related Party Transaction [Line Items]

Shares owned

499,069

Series Seed Preferred Stock | Lundbeckfond Invest A/S

Related Party Transaction [Line Items]

Shares owned

478,749

Series B Preferred Stock | Lundbeckfond Invest A/S

Related Party Transaction [Line Items]

Shares owned

1,326,111

Benefit Plans - Additional Info

Benefit Plans - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
Defined Contribution Savings Plan
Defined Contribution Plan Disclosure [Line Items]
Contribution to defined contribution savings plan	$ 0.1