0001689548-23-000086 | 10-Q | XBRL Viewer | Praxis Precision Medicines INC

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Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2023	May 05, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-39620
Entity Registrant Name	PRAXIS PRECISION MEDICINES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-5195942
Entity Address, Address Line One	99 High Street
Entity Address, Address Line Two	30th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02110
City Area Code	617
Local Phone Number	300-8460
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	PRAX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		62,101,292
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001689548
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 80,839	$ 61,615
Marketable securities	4,983	38,874
Prepaid expenses and other current assets	8,580	10,351
Total current assets	94,402	110,840
Property and equipment, net	865	971
Operating lease right-of-use assets	2,700	2,901
Other non-current assets	416	416
Total assets	98,383	115,128
Current liabilities:
Accounts payable	16,986	14,672
Accrued expenses	9,352	15,850
Operating lease liabilities	1,035	1,005
Current portion of deferred revenue	2,543	2,818
Total current liabilities	29,916	34,345
Long-term liabilities:
Non-current portion of operating lease liabilities	2,225	2,495
Non-current portion of deferred revenue	1,774	2,182
Total liabilities	33,915	39,022
Commitments and contingencies (Note 6)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding as of March 31, 2023 and December 31, 2022	0	0
Common stock, $0.0001 par value; 150,000,000 shares authorized; 57,960,387 shares issued and outstanding as of March 31, 2023, and 49,382,453 shares issued and outstanding as of December 31, 2022	6	5
Additional paid-in capital	632,580	606,918
Accumulated other comprehensive loss	(19)	(173)
Accumulated deficit	(568,099)	(530,644)
Total stockholders’ equity	64,468	76,106
Total liabilities and stockholders’ equity	$ 98,383	$ 115,128

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	57,960,387	49,382,453
Common stock, outstanding (in shares)	57,960,387	49,382,453

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Collaboration revenue	$ 683	$ 0
Operating expenses:
Research and development	25,504	52,652
General and administrative	13,270	16,197
Total operating expenses	38,774	68,849
Loss from operations	(38,091)	(68,849)
Other income:
Other income, net	636	132
Total other income	636	132
Net loss	$ (37,455)	$ (68,717)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.71)	$ (1.51)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.71)	$ (1.51)
Weighted average common shares outstanding, basic (in shares)	53,102,907	45,455,179
Weighted average common shares outstanding, diluted (in shares)	53,102,907	45,455,179

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (37,455)	$ (68,717)
Change in unrealized losses on marketable securities, net of tax	154	(430)
Comprehensive loss	$ (37,301)	$ (69,147)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Condensed Consolidated Statements of Stockholders’ Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2021		45,300,514
Beginning balance at Dec. 31, 2021	$ 250,812	$ 5	$ 567,598	$ (316,615)	$ (176)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	7,886		7,886
Issuance of common stock from at-the-market public offerings, net of issuance and offering costs (in shares)		70,410
Issuance of common stock from at-the-market public offerings, net of issuance costs	1,368		1,368
Vesting of restricted stock awards (in shares)		81,130
Shares withheld for taxes for vesting of restricted stock units (in shares)		(17,850)
Shares withheld for taxes for vesting of restricted stock units	(230)		(230)
Issuance of common stock upon exercise of stock options (in shares)		72,278
Issuance of common stock upon exercise of stock options	333		333
Change in unrealized loss on marketable securities, net of tax	(430)				(430)
Net loss	(68,717)			(68,717)
Ending balance (in shares) at Mar. 31, 2022		45,506,482
Ending balance at Mar. 31, 2022	$ 191,022	$ 5	576,955	(385,332)	(606)
Beginning balance (in shares) at Dec. 31, 2022	49,382,453	49,382,453
Beginning balance at Dec. 31, 2022	$ 76,106	$ 5	606,918	(530,644)	(173)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	7,593		7,593
Issuance of common stock from at-the-market public offerings, net of issuance and offering costs (in shares)		8,403,809
Issuance of common stock from at-the-market public offerings, net of issuance costs	18,096	$ 1	18,095
Vesting of restricted stock awards (in shares)		172,798
Shares withheld for taxes for vesting of restricted stock units (in shares)		(43,317)
Shares withheld for taxes for vesting of restricted stock units	$ (127)		(127)
Issuance of common stock upon exercise of stock options (in shares)	44,644	44,644
Issuance of common stock upon exercise of stock options	$ 101		101
Change in unrealized loss on marketable securities, net of tax	154				154
Net loss	$ (37,455)			(37,455)
Ending balance (in shares) at Mar. 31, 2023	57,960,387	57,960,387
Ending balance at Mar. 31, 2023	$ 64,468	$ 6	$ 632,580	$ (568,099)	$ (19)

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (37,455)	$ (68,717)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	106	93
Stock-based compensation expense	7,593	7,886
Non-cash operating lease expense	201	180
Amortization of premiums and discounts on marketable securities, net	45	375
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,771	(1,061)
Accounts payable	2,314	2,489
Accrued expenses	(6,498)	4,616
Operating lease liabilities	(240)	(26)
Deferred revenue	(683)	0
Other	0	56
Net cash used in operating activities	(32,846)	(54,109)
Cash flows from investing activities:
Purchases of property and equipment	0	(289)
Purchases of marketable securities	0	(83,022)
Maturities of marketable securities	34,000	74,761
Net cash provided by (used in) investing activities	34,000	(8,550)
Cash flows from financing activities:
Proceeds from at-the-market offerings, net of issuance costs	18,096	1,368
Payment of issuance costs for at-the-market offerings	0	(262)
Payments of tax withholdings related to vesting of restricted stock units	(127)	(230)
Proceeds from exercise of stock options	101	333
Net cash provided by financing activities	18,070	1,209
Increase (decrease) in cash, cash equivalents and restricted cash	19,224	(61,450)
Cash, cash equivalents and restricted cash, beginning of period	62,031	139,720
Cash, cash equivalents and restricted cash, end of period	81,255	78,270
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	80,839	77,854
Restricted cash	416	416
Total cash, cash equivalents and restricted cash	$ 81,255	$ 78,270

Nature of the Business	3 Months Ended
Nature of the Business	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	Nature of the Business Praxis Precision Medicines, Inc. (“Praxis” or the “Company”) is a clinical-stage biopharmaceutical company translating insights from genetic epilepsies into the development of therapies for central nervous system, or CNS, disorders characterized by neuronal excitation-inhibition imbalance. Normal brain function requires a delicate balance of excitation and inhibition in neuronal circuits, which, when dysregulated, can lead to abnormal function and both rare and more prevalent neurological disorders. The Company is applying genetic insights to the discovery and development of therapies for neurological disorders through two proprietary platforms, using its understanding of shared biological targets and circuits in the brain. Each platform has multiple programs currently, with significant potential for additional program and indication expansion: •Cerebrum™, the Company's small molecule platform, utilizes deep understanding of neuronal excitability and neuronal networks and applies a series of computational and experimental tools to develop orally available precision therapies •Solidus™, the Company's antisense oligonucleotide, or ASO, platform, is an efficient, targeted precision medicine discovery and development engine anchored on a proprietary, computational methodology The Company's platforms utilize a deliberate, pragmatic and patient-guided approach, leveraging a suite of translational tools, including novel transgenic and predictive translational animal models and electrophysiology markers, to enable an efficient path to proof-of-concept in patients. Through this approach, the Company has established a diversified, multimodal CNS portfolio with four clinical-stage product candidates across movement disorders and epilepsy. For the Company's most advanced product candidate under the Cerebrum™ platform, ulixacaltamide (also known as PRAX-944), topline results from the Phase 2b Essential1 clinical trial in essential tremor ("ET") were announced in the first quarter of 2023. An end-of-Phase 2 meeting is scheduled with the U.S. Food and Drug Administration in June 2023 and the Company intends to initiate a Phase 3 study in ET in the second half of 2023. The Company initiated its PRAX-562 Phase 2 EMBOLD study in the first quarter of 2023 and expects to announce topline results in the fourth quarter of 2023. The Company also announced positive results from its PRAX-628 Phase 1 study in May 2023 and expects to initiate a Phase 2 study in focal epilepsy in the fourth quarter of 2023. For the Company's most advanced product candidate under the Solidus™ platform, PRAX-222, it expects to announce topline results from the first dose cohort of its EMBRAVE study in the second half of 2023. Praxis was incorporated in 2015 and commenced operations in 2016. The Company has funded its operations primarily with proceeds from the issuance of redeemable convertible preferred stock, and from the sale of common stock through an initial public offering, a follow-on public offering and at-the-market offerings under its shelf registration statement. From inception through March 31, 2023, the Company raised $544.1 million in aggregate cash proceeds from these transactions, net of issuance costs. 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. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. Liquidity In accordance with the Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. The Company has incurred recurring losses since its inception, including a net loss of $37.5 million for the three months ended March 31, 2023. In addition, as of March 31, 2023, the Company had an accumulated deficit of $568.1 million. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash, cash equivalents and marketable securities as of March 31, 2023 may not be sufficient to fund operations for at least the next twelve months from the date of issuance of these condensed consolidated financial statements which raises substantial doubt about the Company's ability to continue as a going concern, and the Company will need to obtain additional funding. The Company expects to finance its operations through potential public or private equity financings, debt financings, collaboration agreements or other capital sources. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. The Company’s inability to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies. There can be no assurance that the current operating plan will be achieved or that additional funding will be available on terms acceptable to the Company, or at all. The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The condensed consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles 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 ASUs of the FASB. The significant accounting policies used in preparation of these condensed consolidated financial statements for the three months ended March 31, 2023 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company's 2022 Annual Report on Form 10-K, other than as noted below. Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2023, the condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022, the condensed consolidated statements of comprehensive loss for the three months ended March 31, 2023 and 2022, the condensed consolidated statements of cash flows for the three months ended March 31, 2023 and 2022 and the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of March 31, 2023, the results of its operations for the three months ended March 31, 2023 and 2022 and its cash flows for the three months ended March 31, 2023 and 2022. Financial statement disclosures for the three months ended March 31, 2023 and 2022 are condensed and do not include all disclosures required for an annual set of financial statements in accordance with GAAP. The results for the three months ended March 31, 2023 are not necessarily indicative of results to be expected for the year ended December 31, 2023, any other interim periods, or any future year or period. Use of Estimates The preparation of 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 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 and prepaid research and development expense, collaboration revenue, stock-based compensation expense and the recoverability of the Company’s net deferred tax assets and related valuation allowance. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates. Recently Issued Accounting Pronouncements The Company does not expect any recently issued accounting pronouncements to have a material impact on its financial statements

Marketable Securities

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

The following is a summary of the Company's investment portfolio as of March 31, 2023 and December 31, 2022 (in thousands):


	As of March 31, 2023
			Gross Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	5,002	$	—		$	(19)	$	4,983
Total securities with a maturity of one year or less	$	5,002	$	—		$	(19)	$	4,983

Total available-for-sale securities	$	5,002	$	—		$	(19)	$	4,983


	As of December 31, 2022
			Gross Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	35,042	$	—		$	(163)	$	34,879
Debt securities issued by U.S. government agencies	4,005		—			(10)		3,995
Total securities with a maturity of one year or less	$	39,047	$	—		$	(173)	$	38,874

Total available-for-sale securities	$	39,047	$	—		$	(173)	$	38,874

As of March 31, 2023, the Company had 1 security with a total fair market value of $5.0 million in an unrealized loss position. The Company believes that any unrealized losses associated with the decline in value of its securities is temporary and primarily related to the change in market interest rates since purchase, and believes that it is more likely than not that it will be able to hold its debt securities to maturity. Therefore, the Company anticipates a full recovery of the amortized cost basis of its debt securities at maturity and an allowance was not recognized.

Securities are evaluated for impairment at the end of each reporting period. The Company did not record any impairment related to its available-for-sale securities during the three months ended March 31, 2023 and 2022.

Fair Value Measurements

3 Months Ended

Mar. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset in an orderly transaction between market participants at the measurement date. The Company categorizes financial assets measured at fair value based on a fair value hierarchy. The following fair value hierarchy is used to classify financial assets based on observable inputs and unobservable inputs used to value the financial assets:

•Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical assets;

•Level 2: Quoted prices for similar assets in active markets, quoted prices in markets that are not active, or inputs which are unobservable, either directly or indirectly, for substantially the full term of the asset; or

•Level 3: Prices or valuation techniques that require inputs that are both significant to the valuation of the asset and unobservable.

The following tables present information about the Company’s financial assets measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values as of March 31, 2023 and December 31, 2022 (in thousands):


	As of March 31, 2023
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	62,976	$	—	$	—	$	62,976
Marketable securities:
Corporate debt securities	—		4,983		—		4,983
	$	62,976	$	4,983	$	—	$	67,959


	As of December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	34,181	$	—	$	—	$	34,181
Marketable securities:
Corporate debt securities	—		34,879		—		34,879
Debt securities issued by U.S. government agencies	3,995		—		—		3,995
	$	38,176	$	34,879	$	—	$	73,055

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accrued Expenses

3 Months Ended

Mar. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	March 31, 2023		December 31, 2022
Accrued external research and development expenses	$	6,355	$	10,734
Accrued personnel-related expenses	1,748		2,803
Accrued other expenses	1,249		2,313
Total accrued expenses	$	9,352	$	15,850

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesIn May 2021, the Company entered into a sublease agreement for office space located in Boston, Massachusetts that expires on January 31, 2026, with no option to renew or terminate early. The base rent increases by approximately 2% annually. The Company issued a letter of credit to the landlord related to the security deposit, secured by restricted cash, which is reflected within other non-current assets on the accompanying condensed consolidated balance sheets as of March 31, 2023 and December 31, 2022. This lease qualifies as an operating lease.

UCB Option and License Agreement	3 Months Ended
UCB Option and License Agreement	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
UCB Option and License Agreement	UCB Option and License Agreement In December 2022, the Company entered into an Option and License Agreement (“the Collaboration Agreement”) with UCB Biopharma SRL ("UCB") for the discovery of small molecule therapeutics as potential treatments of KCNT1-related epilepsies. Under the terms of the Collaboration Agreement, the Company has agreed to perform general biology-related research services as part of a mutually agreed upon research plan in exchange for a $5.0 million upfront payment. In addition, the Company provided UCB an exclusive option to in-license global development and commercialization rights to any resulting KCNT1 small molecule development candidate identified as part of the research plan. If UCB exercises its option to in-license global development and commercialization rights, the Collaboration Agreement stipulates that UCB will assume research, development, manufacturing and commercialization responsibilities and costs. Under the terms of the Collaboration Agreement, the Company will be eligible to receive an option fee and future success-based development and commercialization milestone payments, totaling up to $98.5 million, in addition to tiered royalties on net sales of any resulting products from the Collaboration Agreement. The Company concluded that UCB is a customer, and as such, the arrangement falls within the scope of Topic 606. At the commencement of the Collaboration Agreement, the Company identified one performance obligation, which was to perform the research services for UCB. The Company determined the transaction price to be $5.0 million, comprised of the upfront payment it received. The option provided to UCB was determined not to be a material right. The Company recognizes revenue for its research services performance obligation over time using an input method over the duration of the research services. During the three months ended March 31, 2023, the Company recognized $0.7 million in collaboration revenue related to the Collaboration Agreement in the condensed consolidated statement of operations. As of March 31, 2023, $4.3 million was included in deferred revenue in the condensed consolidated balance sheet, of which $2.5 million was classified as current.

Common Stock and Preferred Stock

3 Months Ended

Mar. 31, 2023

Stockholders' Equity Note [Abstract]

Common Stock and Preferred Stock

Common Stock

As of March 31, 2023 and December 31, 2022, the authorized capital stock of the Company included 150,000,000 shares of common stock, $0.0001 par value.

As of March 31, 2023 and December 31, 2022, the Company did not hold any treasury shares.

Shares Reserved for Future Issuance

The Company has reserved the following shares of common stock for future issuance:


	March 31, 2023	December 31, 2022
Shares reserved for exercise of outstanding stock options	10,691,062	8,838,028
Shares reserved for future awards under the 2020 Stock Option and Incentive Plan	2,113,892	1,650,955
Shares reserved for future awards under the 2020 Employee Stock Purchase Plan	1,167,024	839,922
Shares reserved for vesting of restricted stock units	754,756	743,950
Total shares of authorized common stock reserved for future issuance	14,726,734	12,072,855

Preferred Stock

As of March 31, 2023 and December 31, 2022, the authorized capital stock of the Company included 10,000,000 shares of undesignated preferred stock, $0.0001 par value

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-URI https://asc.fasb.org/topic&trid=2208762

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 505
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-Section 50
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-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496171-112644

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 14
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496171-112644

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 18
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 18
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 505
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stock-Based Compensation

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

2020 Stock Option and Incentive Plan

The total number of shares of common stock authorized for issuance under the 2020 Stock Option and Incentive Plan (the "2020 Plan”) as of March 31, 2023 and December 31, 2022 was 9,918,602 shares and 7,449,480 shares, respectively.

2017 Stock Incentive Plan

The total number of shares of common stock authorized for issuance under the 2017 Stock Incentive Plan (the "2017 Plan") as of March 31, 2023 and December 31, 2022 was 5,937,763 shares. Any authorization to issue new options under the 2017 Plan was cancelled upon the effectiveness of the 2020 Plan and no further awards will be granted under the 2017 Plan.

2020 Employee Stock Purchase Plan

The total number of shares of common stock authorized for issuance under the 2020 Employee Stock Purchase Plan (the "2020 ESPP”) as of March 31, 2023 and December 31, 2022 was 1,308,408 shares and 981,306 shares, respectively.

Restricted Stock Units

The following table summarizes the Company’s restricted stock unit activity:


	Shares	Weighted Average Grant Date Fair Value
Unvested as of December 31, 2022	743,950	$	23.07
Issued	301,550	2.95
Vested	(172,798)	27.89
Forfeited	(117,946)	14.27
Unvested as of March 31, 2023	754,756	$	15.40

As of March 31, 2023, total unrecognized compensation cost related to unvested restricted stock units was $10.5 million, which is expected to be recognized over a weighted-average period of 2.50 years.

Stock Options

The following table summarizes the Company’s stock option activity:


	Number of Shares	Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
				(In years)	(In thousands)
Outstanding as of December 31, 2022	8,838,028	$	13.93
Granted	2,629,255	2.97
Exercised	(44,644)	2.27			$	83
Cancelled or Forfeited	(731,577)	10.28
Outstanding as of March 31, 2023	10,691,062	$	11.53	8.23	$	23
Exercisable as of March 31, 2023	4,517,923	$	13.74	7.33	$	23
Vested and expected to vest as of March 31, 2023	10,488,056	$	11.47	8.46	$	23

Valuation of Stock Options

The weighted-average assumptions that the Company used in the Black-Scholes option pricing model to determine the grant-date fair value of stock options granted to employees and non-employees on the date of grant were as follows for the three months ended March 31, 2023:


	Three Months Ended March 31,
	2023
Risk-free interest rate	3.51		%
Expected term (in years)	6.00
Expected volatility	88.22		%
Expected dividend yield	—		%
Weighted average grant-date fair value per share	$	2.22

As of March 31, 2023, total unrecognized compensation cost related to unvested stock options was $40.8 million, which is expected to be recognized over a weighted-average period of 2.05 years.

Stock-Based Compensation

Stock-based compensation expense was allocated as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Research and development	$	2,223	$	3,214
General and administrative	5,370		4,672
Total stock-based compensation expense	$	7,593	$	7,886

Net Loss per Share

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Net Loss per Share

The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive:


	Three Months Ended March 31,
	2023	2022
Outstanding stock options	10,691,062	7,862,576
Unvested restricted stock units	754,756	840,277
Potential shares issuable under the 2020 ESPP	179,768	30,341
	11,625,586	8,733,194

Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsOn September 11, 2019, the Company entered into a Cooperation and License Agreement (the “License Agreement”) with RogCon Inc. (“RogCon”). Under the License Agreement, RogCon granted to the Company an exclusive, worldwide license under RogCon's intellectual property to research, develop and commercialize products for the treatment of all forms of epilepsy and/or neurodevelopmental disorders in each case caused by any mutation of the SCN2A gene. Pursuant to the terms of the License Agreement, the Company will conduct, at its own cost and expense, the research and development activities assigned to it under the associated research plan. In addition, the Company is responsible for reimbursing RogCon for any costs associated with research and development activities RogCon performs at the request of the Company. One of the founders of RogCon became the Company's General Counsel in June 2020. The Company continues to reimburse RogCon for its out-of-pocket costs incurred for activities performed under the License Agreement. Expenses incurred during all periods presented were not material.

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the condensed consolidated financial statements to provide additional evidence for certain estimates or to identify matters that require additional disclosure. The Company has concluded that no subsequent events have occurred that require disclosure.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles 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 ASUs of the FASB. The significant accounting policies used in preparation of these condensed consolidated financial statements for the three months ended March 31, 2023 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company's 2022 Annual Report on Form 10-K, other than as noted below.
Unaudited Interim Condensed Consolidated Financial Information	Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2023, the condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022, the condensed consolidated statements of comprehensive loss for the three months ended March 31, 2023 and 2022, the condensed consolidated statements of cash flows for the three months ended March 31, 2023 and 2022 and the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position as of March 31, 2023, the results of its operations for the three months ended March 31, 2023 and 2022 and its cash flows for the three months ended March 31, 2023 and 2022. Financial statement disclosures for the three months ended March 31, 2023 and 2022 are condensed and do not include all disclosures required for an annual set of financial statements in accordance with GAAP. The results for the three months ended March 31, 2023 are not necessarily indicative of results to be expected for the year ended December 31, 2023, any other interim periods, or any future year or period.
Use of Estimates	Use of Estimates The preparation of 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 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 and prepaid research and development expense, collaboration revenue, stock-based compensation expense and the recoverability of the Company’s net deferred tax assets and related valuation allowance. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ materially from those estimates.
Recently Issued Accounting Pronouncements	Recently Issued Accounting PronouncementsThe Company does not expect any recently issued accounting pronouncements to have a material impact on its financial statements

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Investment Portfolio

The following is a summary of the Company's investment portfolio as of March 31, 2023 and December 31, 2022 (in thousands):


	As of March 31, 2023
			Gross Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	5,002	$	—		$	(19)	$	4,983
Total securities with a maturity of one year or less	$	5,002	$	—		$	(19)	$	4,983

Total available-for-sale securities	$	5,002	$	—		$	(19)	$	4,983


	As of December 31, 2022
			Gross Unrealized					Estimated
	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	35,042	$	—		$	(163)	$	34,879
Debt securities issued by U.S. government agencies	4,005		—			(10)		3,995
Total securities with a maturity of one year or less	$	39,047	$	—		$	(173)	$	38,874

Total available-for-sale securities	$	39,047	$	—		$	(173)	$	38,874

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2023

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured At Fair Value On A Recurring Basis


	As of March 31, 2023
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	62,976	$	—	$	—	$	62,976
Marketable securities:
Corporate debt securities	—		4,983		—		4,983
	$	62,976	$	4,983	$	—	$	67,959


	As of December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents:
Money market funds	$	34,181	$	—	$	—	$	34,181
Marketable securities:
Corporate debt securities	—		34,879		—		34,879
Debt securities issued by U.S. government agencies	3,995		—		—		3,995
	$	38,176	$	34,879	$	—	$	73,055

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2023

Payables and Accruals [Abstract]

Summary of Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	March 31, 2023		December 31, 2022
Accrued external research and development expenses	$	6,355	$	10,734
Accrued personnel-related expenses	1,748		2,803
Accrued other expenses	1,249		2,313
Total accrued expenses	$	9,352	$	15,850

Common Stock and Preferred Stock (Tables)

3 Months Ended

Mar. 31, 2023

Stockholders' Equity Note [Abstract]

Summary of Common Stock Reserved For Future Issuance

The Company has reserved the following shares of common stock for future issuance:


	March 31, 2023	December 31, 2022
Shares reserved for exercise of outstanding stock options	10,691,062	8,838,028
Shares reserved for future awards under the 2020 Stock Option and Incentive Plan	2,113,892	1,650,955
Shares reserved for future awards under the 2020 Employee Stock Purchase Plan	1,167,024	839,922
Shares reserved for vesting of restricted stock units	754,756	743,950
Total shares of authorized common stock reserved for future issuance	14,726,734	12,072,855

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Restricted Stock Activity

The following table summarizes the Company’s restricted stock unit activity:


	Shares	Weighted Average Grant Date Fair Value
Unvested as of December 31, 2022	743,950	$	23.07
Issued	301,550	2.95
Vested	(172,798)	27.89
Forfeited	(117,946)	14.27
Unvested as of March 31, 2023	754,756	$	15.40

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity:


	Number of Shares	Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
				(In years)	(In thousands)
Outstanding as of December 31, 2022	8,838,028	$	13.93
Granted	2,629,255	2.97
Exercised	(44,644)	2.27			$	83
Cancelled or Forfeited	(731,577)	10.28
Outstanding as of March 31, 2023	10,691,062	$	11.53	8.23	$	23
Exercisable as of March 31, 2023	4,517,923	$	13.74	7.33	$	23
Vested and expected to vest as of March 31, 2023	10,488,056	$	11.47	8.46	$	23

Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model


	Three Months Ended March 31,
	2023
Risk-free interest rate	3.51		%
Expected term (in years)	6.00
Expected volatility	88.22		%
Expected dividend yield	—		%
Weighted average grant-date fair value per share	$	2.22

Summary of Stock-Based Compensation Expense

Stock-based compensation expense was allocated as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Research and development	$	2,223	$	3,214
General and administrative	5,370		4,672
Total stock-based compensation expense	$	7,593	$	7,886

Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Summary of Antidilutive Securities Excluded From Computation of Earnings Per Share


	Three Months Ended March 31,
	2023	2022
Outstanding stock options	10,691,062	7,862,576
Unvested restricted stock units	754,756	840,277
Potential shares issuable under the 2020 ESPP	179,768	30,341
	11,625,586	8,733,194

Nature of the Business - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Proceeds from issuance or sale of equity	$ 544,100
Net loss	37,455	$ 68,717
Accumulated deficit	$ 568,099		$ 530,644

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Marketable Securities - Investment Profile (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, cost, current	$ 5,002	$ 39,047
Total available-for-sale securities, cost	5,002	39,047
Available-for-sale, gross unrealized gain, current, before tax	0	0
Total available-for-sale securities, gross unrealized gains	0	0
Available-for-sale, gross unrealized loss, current, before tax	(19)	(173)
Total available-for-sale, gross unrealized losses	(19)	(173)
Estimated fair value, available-for-sale, current	4,983	38,874
Total available-for-sale securities, estimated fair value	4,983	38,874
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, cost, current	5,002	35,042
Available-for-sale, gross unrealized gain, current, before tax	0	0
Available-for-sale, gross unrealized loss, current, before tax	(19)	(163)
Estimated fair value, available-for-sale, current	$ 4,983	34,879
Debt securities issued by U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, cost, current		4,005
Available-for-sale, gross unrealized gain, current, before tax		0
Available-for-sale, gross unrealized loss, current, before tax		(10)
Estimated fair value, available-for-sale, current		$ 3,995

Marketable Securities - Additional Information (Details) $ in Millions	Mar. 31, 2023 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Number of securities \| security	1
Securities, unrealized loss position, fair value \| $	$ 5.0

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 67,959	$ 73,055
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	62,976	38,176
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	4,983	34,879
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	62,976	34,181
Money market funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	62,976	34,181
Money market funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Money market funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,983	34,879
Corporate debt securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Corporate debt securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,983	34,879
Corporate debt securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0	0
Debt securities issued by U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		3,995
Debt securities issued by U.S. government agencies \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		3,995
Debt securities issued by U.S. government agencies \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		0
Debt securities issued by U.S. government agencies \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		$ 0

Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued external research and development expenses	$ 6,355	$ 10,734
Accrued personnel-related expenses	1,748	2,803
Accrued other expenses	1,249	2,313
Total accrued expenses	$ 9,352	$ 15,850

Commitments and Contingencies - Additional Information (Details)	May 31, 2021
Office Space in Boston Massachusetts
Loss Contingencies [Line Items]
Percentage increase in annual base rent	2.00%

UCB Option and License Agreement - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Collaboration revenue	$ 683	$ 0
Current portion of deferred revenue	2,543		$ 2,818
UCB \| License
Disaggregation of Revenue [Line Items]
Upfront payment	4,300		5,000
Milestone payments			98,500
Transaction price			$ 5,000
Collaboration revenue	700
Current portion of deferred revenue	$ 2,500

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Common Stock and Preferred Stock - Additional Information (Details) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Stockholders' Equity Note [Abstract]
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Treasury stock (in shares)	0	0
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001

Common Stock and Preferred Stock - Summary of Common Stock Reserved For Future Issuance (Details) - shares	Mar. 31, 2023	Dec. 31, 2022
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	14,726,734	12,072,855
Shares reserved for exercise of outstanding stock options
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	10,691,062	8,838,028
Share-based payment arrangement \| Shares reserved for future awards under the 2020 Stock Option and Incentive Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	2,113,892	1,650,955
Share-based payment arrangement \| Shares reserved for future awards under the 2020 Employee Stock Purchase Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	1,167,024	839,922
Shares reserved for vesting of restricted stock units
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Common stock reserved for future issuance (in shares)	754,756	743,950

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Unvested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested restricted stock units	$ 10.5
Weighted-average period (in years)	2 years 6 months
Shares reserved for exercise of outstanding stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average period (in years)	2 years 18 days
Unrecognized compensation expense related to unvested stock based awards	$ 40.8
2020 Employee Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	9,918,602	7,449,480
2017 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	5,937,763	5,937,763
2020 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	1,308,408	981,306

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Unvested restricted stock units	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Shares
Beginning balance (in shares) \| shares	743,950
Issued (in shares) \| shares	301,550
Vested (in shares) \| shares	(172,798)
Forfeited (in shares) \| shares	(117,946)
Ending balance (in shares) \| shares	754,756
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) \| $ / shares	$ 23.07
Issued (in dollars per share) \| $ / shares	2.95
Vested (in dollars per share) \| $ / shares	27.89
Forfeitures (in dollars per shares) \| $ / shares	14.27
Unvested ending balance (in dollars per share) \| $ / shares	$ 15.40

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) \| shares	8,838,028
Granted (in shares) \| shares	2,629,255
Exercised (in shares) \| shares	(44,644)
Canceled or forfeited (in shares) \| shares	(731,577)
Ending balance (in shares) \| shares	10,691,062
Number of shares exercisable (in shares) \| shares	4,517,923
Vested and expected to vest (in shares) \| shares	10,488,056
Weighted Average Exercise Price per Share
Beginning balance (in dollars per share) \| $ / shares	$ 13.93
Granted (in dollars per share) \| $ / shares	2.97
Exercised (in dollars per share) \| $ / shares	2.27
Cancelled or forfeited (in dollars per share) \| $ / shares	10.28
Ending balance (in dollars per share) \| $ / shares	11.53
Exercisable (in dollars per share) \| $ / shares	13.74
Vested and expected to vest (in dollars per share) \| $ / shares	$ 11.47
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average remaining contractual term outstanding	8 years 2 months 23 days
Weighted average remaining contractual term exercisable	7 years 3 months 29 days
Weighted average remaining contractual term vested and expected to vest	8 years 5 months 15 days
Aggregate intrinsic value exercised \| $	$ 83
Aggregate intrinsic value outstanding \| $	23
Aggregate intrinsic value exercisable \| $	23
Aggregate intrinsic value vested and expected to vest \| $	$ 23

Stock-Based Compensation - Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model (Details)	3 Months Ended
	Mar. 31, 2023 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	3.51%
Expected term (in years)	6 years
Expected volatility	88.22%
Expected dividend yield	0.00%
Shares reserved for exercise of outstanding stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value per share (in dollars per share)	$ 2.22

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 7,593	$ 7,886
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	2,223	3,214
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 5,370	$ 4,672

Net Loss per Share - Summary of antidilutive securities excluded from computation of earnings per share (Details) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	11,625,586	8,733,194
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	10,691,062	7,862,576
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	754,756	840,277
Potential shares issuable under the 2020 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	179,768	30,341