Praxis Precision Medicines (PRAX) 10-K 5 Mar 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Mar. 01, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 147.4
Entity Common Stock, Shares Outstanding		13,238,349
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001689548

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)		Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents		$ 81,300,000	$ 61,615,000
Marketable securities		0	38,874,000
Prepaid expenses and other current assets		3,580,000	10,351,000
Total current assets		84,880,000	110,840,000
Property and equipment, net		588,000	971,000
Operating lease right-of-use assets		2,064,000	2,901,000
Other non-current assets		416,000	416,000
Total assets		87,948,000	115,128,000
Current liabilities:
Accounts payable		5,815,000	14,672,000
Accrued expenses		7,416,000	15,850,000
Current operating lease liabilities		1,126,000	1,005,000
Current portion of deferred revenue		1,392,000	2,818,000
Total current liabilities		15,749,000	34,345,000
Long-term liabilities:
Non-current portion of operating lease liabilities		1,369,000	2,495,000
Non-current portion of deferred revenue		1,161,000	2,182,000
Total liabilities		18,279,000	39,022,000
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding as of December 31, 2023 and December 31, 2022	[1]	0	0
Common stock, $0.0001 par value; 150,000,000 shares authorized; 8,791,877 shares issued and outstanding as of December 31, 2023, and 3,292,163 shares issued and outstanding as of December 31, 2022	[1]	13,000	5,000
Additional paid-in capital		723,577,000	606,918,000
Accumulated other comprehensive loss		0	(173,000)
Accumulated deficit		(653,921,000)	(530,644,000)
Total stockholders’ equity		69,669,000	76,106,000
Total liabilities and stockholders’ equity		$ 87,948,000	$ 115,128,000
[1] Results have been retroactively adjusted to reflect the 1-for-15 reverse stock split effected on November 28, 2023. See Note 2 for details.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical)	Dec. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share) | $ / shares	$ 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 USD per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, outstanding (in shares)	8,791,877	3,292,163
Common stock, issued (in shares)	8,791,877	3,292,163

Consolidated Statements of Oper

Consolidated Statements of Operations $ in Thousands		12 Months Ended
		Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Income Statement [Abstract]
Collaboration revenue		$ 2,447	$ 0
Operating expenses:
Research and development		86,766	155,040
General and administrative		42,054	59,946
Total operating expenses		128,820	214,986
Loss from operations		(126,373)	(214,986)
Other income:
Other income, net		3,096	957
Total other income		3,096	957
Net loss		$ (123,277)	$ (214,029)
Net loss per share attributable to common stockholders, basic (in usd per share) | $ / shares	[1]	$ (18.69)	$ (69.65)
Net loss per share attributable to common stockholders, diluted (in usd per share) | $ / shares	[1]	$ (18.69)	$ (69.65)
Weighted average common shares outstanding, basic (in shares) | shares	[1]	6,594,316	3,073,100
Weighted average common shares outstanding, diluted (in shares) | shares	[1]	6,594,316	3,073,100
[1] Results have been retroactively adjusted to reflect the 1-for-15 reverse stock split effected on November 28, 2023. See Note 2 for details.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (123,277)	$ (214,029)
Change in unrealized loss on marketable securities, net of tax	173	3
Comprehensive loss	$ (123,104)	$ (214,026)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Follow-On Offering	At-The-Market Offering	Common Stock		Common Stock Follow-On Offering		Common Stock At-The-Market Offering		Additional Paid-In Capital	Additional Paid-In Capital Follow-On Offering	Additional Paid-In Capital At-The-Market Offering	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2021	[1]				3,020,034
Beginning balance at Dec. 31, 2021		$ 250,812			$ 5	[1]					$ 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 and follow-on public offerings (in shares)	[1]				4,694
Issuance of common stock from at-the-market and follow-on public offerings		1,368									1,368
Vesting of restricted stock units (in shares)	[1]				5,408
Shares withheld for taxes for vesting of restricted stock units (in shares)	[1]				(1,190)
Shares withheld for taxes for vesting of restricted stock units		(230)									(230)
Issuance of common stock upon exercise of stock options (in shares)	[1]				4,818
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	[1]				3,033,764
Ending balance at Mar. 31, 2022		191,022			$ 5	[1]					576,955			(385,332)	(606)
Beginning balance (in shares) at Dec. 31, 2021	[1]				3,020,034
Beginning balance at Dec. 31, 2021		250,812			$ 5	[1]					567,598			(316,615)	(176)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in unrealized loss on marketable securities, net of tax		3
Net loss		$ (214,029)
Ending balance (in shares) at Dec. 31, 2022		3,292,163			3,292,163	[2]
Ending balance at Dec. 31, 2022		$ 76,106			$ 5	[1]					606,918			(530,644)	(173)
Beginning balance (in shares) at Mar. 31, 2022	[1]				3,033,764
Beginning balance at Mar. 31, 2022		191,022			$ 5	[1]					576,955			(385,332)	(606)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense		7,611									7,611
Issuance of common stock from at-the-market and follow-on public offerings (in shares)	[1]				3,443
Issuance of common stock from at-the-market and follow-on public offerings		454									454
Vesting of restricted stock units (in shares)	[1]				424
Shares withheld for taxes for vesting of restricted stock units (in shares)	[1]				(148)
Shares withheld for taxes for vesting of restricted stock units		(17)									(17)
Issuance of common stock upon exercise of stock options (in shares)	[1]				876
Issuance of common stock upon exercise of stock options		67									67
Change in unrealized loss on marketable securities, net of tax		(74)													(74)
Net loss		(60,194)												(60,194)
Ending balance (in shares) at Jun. 30, 2022	[1]				3,038,359
Ending balance at Jun. 30, 2022		138,869			$ 5	[1]					585,070			(445,526)	(680)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense		6,730									6,730
Issuance of common stock from at-the-market and follow-on public offerings (in shares)	[1]				73,667
Issuance of common stock from at-the-market and follow-on public offerings		2,962									2,962
Vesting of restricted stock units (in shares)	[1]				354
Shares withheld for taxes for vesting of restricted stock units (in shares)	[1]				(109)
Shares withheld for taxes for vesting of restricted stock units		(6)									(6)
Issuance of common stock upon exercise of stock options (in shares)	[1]				12,016
Issuance of common stock upon exercise of stock options		409									409
Change in unrealized loss on marketable securities, net of tax		144													144
Net loss		(43,945)												(43,945)
Ending balance (in shares) at Sep. 30, 2022	[1]				3,124,287
Ending balance at Sep. 30, 2022		105,163			$ 5	[1]					595,165			(489,471)	(536)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance costs		109
Stock-based compensation expense		6,366									6,366
Issuance of common stock from at-the-market and follow-on public offerings (in shares)	[1]				161,323
Issuance of common stock from at-the-market and follow-on public offerings		5,231									5,231
Issuance of common stock under employee stock purchase plan (in shares)	[1]				5,982
Issuance of common stock under employee stock purchase plan		163									163
Vesting of restricted stock units (in shares)	[1]				800
Shares withheld for taxes for vesting of restricted stock units (in shares)	[1]				(229)
Shares withheld for taxes for vesting of restricted stock units		(7)									(7)
Issuance of common stock upon exercise of stock options (in shares)	[1]				0
Issuance of common stock upon exercise of stock options		0									0
Change in unrealized loss on marketable securities, net of tax		363													363
Net loss		$ (41,173)												(41,173)
Ending balance (in shares) at Dec. 31, 2022		3,292,163			3,292,163	[2]
Ending balance at Dec. 31, 2022		$ 76,106			$ 5	[1]					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 and follow-on public offerings (in shares)	[2]				560,253
Issuance of common stock from at-the-market and follow-on public offerings		18,096			$ 1	[2]					18,095
Vesting of restricted stock units (in shares)	[2]				11,516
Shares withheld for taxes for vesting of restricted stock units (in shares)	[2]				(2,875)
Shares withheld for taxes for vesting of restricted stock units		(127)									(127)
Issuance of common stock upon exercise of stock options (in shares)	[2]				2,970
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	[2]				3,864,027
Ending balance at Mar. 31, 2023		$ 64,468			$ 6	[2]					632,580			(568,099)	(19)
Beginning balance (in shares) at Dec. 31, 2022		3,292,163			3,292,163	[2]
Beginning balance at Dec. 31, 2022		$ 76,106			$ 5	[1]					606,918			(530,644)	(173)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		3,281
Change in unrealized loss on marketable securities, net of tax		$ 173
Net loss		$ (123,277)
Ending balance (in shares) at Dec. 31, 2023		8,791,877			8,791,877	[2]
Ending balance at Dec. 31, 2023		$ 69,669			$ 13	[2]					723,577			(653,921)	0
Beginning balance (in shares) at Mar. 31, 2023	[2]				3,864,027
Beginning balance at Mar. 31, 2023		64,468			$ 6	[2]					632,580			(568,099)	(19)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense		5,775									5,775
Issuance of common stock from at-the-market and follow-on public offerings (in shares)	[2]						4,296,646		392,541
Issuance of common stock from at-the-market and follow-on public offerings			$ 63,439	$ 6,032			$ 6	[2]	$ 1	[2]		$ 63,433	$ 6,031
Issuance of common stock under employee stock purchase plan (in shares)	[2]				15,663
Issuance of common stock under employee stock purchase plan		208									208
Vesting of restricted stock units (in shares)	[2]				720
Shares withheld for taxes for vesting of restricted stock units (in shares)	[2]				(249)
Shares withheld for taxes for vesting of restricted stock units		(4)									(4)
Change in unrealized loss on marketable securities, net of tax		19													19
Net loss		(34,312)												(34,312)
Ending balance (in shares) at Jun. 30, 2023	[2]				8,569,348
Ending balance at Jun. 30, 2023		105,625			$ 13	[2]					708,023			(602,411)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance costs		4,484
Stock-based compensation expense		5,763									5,763
Vesting of restricted stock units (in shares)	[2]				233
Shares withheld for taxes for vesting of restricted stock units (in shares)	[2]				(70)
Shares withheld for taxes for vesting of restricted stock units		(1)									(1)
Issuance of common stock upon exercise of stock options (in shares)	[2]				311
Issuance of common stock upon exercise of stock options		1									1
Net loss		(24,632)												(24,632)
Ending balance (in shares) at Sep. 30, 2023	[2]				8,569,822
Ending balance at Sep. 30, 2023		86,756			$ 13	[2]					713,786			(627,043)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense		5,726									5,726
Issuance of common stock from at-the-market and follow-on public offerings (in shares)	[2]				212,453
Issuance of common stock from at-the-market and follow-on public offerings		3,964									3,964
Issuance of common stock under employee stock purchase plan (in shares)	[2]				9,027
Issuance of common stock under employee stock purchase plan		106									106
Vesting of restricted stock units (in shares)	[2]				824
Shares withheld for taxes for vesting of restricted stock units (in shares)	[2]				(249)
Shares withheld for taxes for vesting of restricted stock units		(5)									(5)
Net loss		$ (26,878)												(26,878)
Ending balance (in shares) at Dec. 31, 2023		8,791,877			8,791,877	[2]
Ending balance at Dec. 31, 2023		$ 69,669			$ 13	[2]					$ 723,577			$ (653,921)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance costs		$ 123
[1] Results have been retroactively adjusted to reflect the 1-for-15 reverse stock split effected on November 28, 2023. See Note 2 for details. Results have been retroactively adjusted to reflect the 1-for-15 reverse stock split effected on November 28, 2023. See Note 2 for details.

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands		3 Months Ended
	Nov. 28, 2023	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Statement of Stockholders' Equity [Abstract]
Stock issuance costs		$ 123	$ 4,484	$ 109
Stock split, conversion ratio	0.0667

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (123,277)	$ (214,029)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	432	419
Stock-based compensation expense	24,857	28,593
Non-cash operating lease expense	837	752
Amortization of premiums and discounts on marketable securities, net	47	1,003
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	6,772	547
Accounts payable	(8,855)	3,892
Accrued expenses	(8,497)	(10,465)
Operating lease liabilities	(1,005)	(811)
Deferred revenue	(2,447)	5,000
Other	0	56
Net cash used in operating activities	(111,136)	(185,043)
Cash flows from investing activities:
Purchases of property and equipment	(50)	(444)
Purchases of marketable securities	0	(83,022)
Maturities of marketable securities	39,000	180,355
Net cash provided by investing activities	38,950	96,889
Cash flows from financing activities:
Payment of issuance costs for at-the-market offerings	0	(262)
Payments of tax withholdings related to vesting of restricted stock units	(137)	(260)
Proceeds from exercise of options and employee stock purchase plan purchases	416	1,426
Net cash provided by financing activities	91,871	10,465
Increase (decrease) in cash, cash equivalents and restricted cash	19,685	(77,689)
Cash, cash equivalents and restricted cash, beginning of period	62,031	139,720
Cash, cash equivalents and restricted cash, end of period	81,716	62,031
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	81,300	61,615
Restricted cash	416	416
Total cash, cash equivalents and restricted cash	81,716	62,031
At-The-Market Offering
Cash flows from financing activities:
Proceeds from stock offerings, net of issuance costs	28,153	9,561
Supplemental disclosures of non-cash activities:
Offering costs from follow-on public offering included in accounts payable	63	0
Follow-On Offering
Cash flows from financing activities:
Proceeds from stock offerings, net of issuance costs	63,439	0
Supplemental disclosures of non-cash activities:
Offering costs from follow-on public offering included in accounts payable	$ 184	$ 0

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of 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 ("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 ("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 (formerly known as PRAX-944), it expects to announce topline results from the Phase 3 Essential3 clinical trial in essential tremor in the second half of 2024. Within the Company's PRAX-628 program, it initiated a Phase 2a Photo-Paroxysmal Response ("PPR") study in 2023 and expects to report topline results in the first quarter of 2024. The Company also plans to initiate a Phase 2 study of PRAX-628 in focal epilepsy in the second half of 2024. The Company's PRAX-562 Phase 2 EMBOLD study was initiated in the first quarter of 2023, with initial cohorts in SCN2A-DEE and SCN8A-DEE, and it expects to announce topline results for both cohorts in mid- 2024. For the Company's most advanced product candidate under the Solidus™ platform, PRAX-222, it initiated the EMBRAVE study in the second quarter of 2023, which completed in the fourth quarter 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 ("IPO"), follow-on public offerings and at-the-market offerings under its shelf registration statement. From inception through December 31, 2023, the Company raised $617.5 million in aggregate cash proceeds from these transactions, net of issuance costs. In January 2024, the Company raised net proceeds of $161.7 million from a follow-on public offering and $5.3 million from at-the-market offerings. 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 consolidated financial statements are issued. The Company has incurred recurring losses since its inception, including a net loss of $123.3 million for the year ended December 31, 2023. In addition, as of December 31, 2023, the Company had an accumulated deficit of $653.9 million. The Company expects to continue to generate operating losses for the foreseeable future.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with 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. On November 28, 2023, the Company filed a Certificate of Amendment to the Company's Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a 1-for-15 reverse stock split of its common stock (the "Reverse Stock Split"). The Reverse Stock Split became effective at 5:00 p.m., Eastern Time, on November 28, 2023. As a result of the Reverse Stock Split, every 15 shares of the Company's issued and outstanding common stock were automatically reclassified into one validly issued, fully-paid and non-assessable share of common stock. Any fractional post-split shares as a result of the Reverse Stock Split were rounded down to the nearest whole post-split share. The Reverse Stock Split did not affect the number of authorized shares of common stock or the par value of the common stock. All share amounts and per share amounts disclosed in this Annual Report on Form 10-K have been restated to reflect the Reverse Stock Split on a retroactive basis in all periods presented. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Praxis Security Corporation and Praxis Precision Medicines Australia Pty Ltd. All intercompany transactions have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, accrued and prepaid research and development expense, 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. Segments 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 purposes of assessing performance and allocating resources. The majority of the Company’s long-lived assets are held in the United States. Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents. Cash and cash equivalents include cash held in banks and amounts held in interest-bearing insured liquid deposit funds. Cash equivalents are carried at cost, which approximates their fair market value. Restricted cash comprises letters of credit for the benefit of the landlord in connection with the Company’s lease facilities. Restricted cash is classified as either current or non-current based on the terms of the underlying lease arrangement. The following table presents cash and cash equivalents and restricted cash as reported on the consolidated balance sheets that equal the total amounts on the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 81,300 $ 61,615 Restricted cash 416 416 Total cash, cash equivalents and restricted cash as shown on the consolidated statements of cash flows $ 81,716 $ 62,031 Marketable Securities The Company may invest its excess cash in money market funds and debt instruments of the U.S. Treasury, financial institutions, corporations and U.S. government agencies with strong credit ratings and an investment grade rating at or above A-1 or P-1 by two of the three nationally recognized statistical rating organizations. The Company does not believe that it is exposed to more than a nominal amount of credit risk related to any marketable securities it may invest in. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity, and periodically reviews and modifies these guidelines to maximize trends in yields and interest rates without compromising safety and liquidity. The Company classifies its investments in debt instruments as available-for-sale. Available-for-sale investments are reported at fair value at each balance sheet date, and include any unrealized holding gains and losses in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses are included in the Company's consolidated statements of operations. All of the Company's available-for-sale securities are available for use in its current operations. As a result, the Company has categorized all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The Company did not hold any marketable securities as of December 31, 2023, and held $38.9 million of marketable securities as of December 31, 2022. The Company evaluates securities for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the Company, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit-related is recognized in other comprehensive loss, net of applicable taxes unless deemed other than temporary. Concentrations of Credit Risk and Significant Suppliers and License Agreements Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents, restricted cash and marketable securities. The Company's investment portfolio may include money market funds, marketable debt securities, including debt securities issued by U.S. government agencies and corporations, and commercial paper. The Company investments are limited to investment-grade securities with strong credit ratings with the objective of maintaining safety and liquidity. The Company also maintains deposits in accredited financial institutions in excess of federally insured limits. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (the “FDIC”) up to $250,000. As of December 31, 2023 and 2022, the Company’s primary operating accounts significantly exceeded the FDIC limits. The Company deposits its cash in financial institutions that it believes have high credit quality, and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply materials for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relies, and expects to continue to rely, on a small number of third-party manufacturers to produce and process its current and potential product candidates and to manufacture supply of its current and potential product candidates for preclinical and clinical activities. These programs could be adversely affected by a significant interruption in the supply of the necessary materials. The Company is also dependent on third parties who provide license rights used in the development of certain programs. The Company could experience delays in the development of its programs if any of these license agreements are terminated, if the Company fails to meet the obligations required under its arrangements, or if the Company is unable to successfully secure new strategic alliances or licensing agreements. Off-Balance Sheet Risk As of December 31, 2023 and 2022, the Company had no off-balance sheet risk such as foreign exchange contracts, option contracts or other hedging arrangements. Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. The fair values of the Company’s financial assets and liabilities reflect the Company’s estimate of the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1: Quoted prices in active markets for identical assets or liabilities. • Level 2: Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3: Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. An entity may choose to measure many financial instruments and certain other items at fair value at specified election dates. Subsequent unrealized gains and losses on items for which the fair value option has been elected will be reported in earnings. Items measured at fair value on a recurring basis include cash equivalents and marketable securities (Note 4 and Note 5). The carrying amounts reflected in the consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. Property and Equipment Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the following estimated useful lives of the assets: Estimated Useful Life Office furniture and equipment 5 years Laboratory equipment 3 years Computer equipment 3 years Upon disposal, retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. The Company did not record any impairment losses on long-lived assets during the years ended December 31, 2023 and 2022. Leases The Company accounts for leases in accordance with ASC 842. 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 December 31, 2023 and 2022 did not include any lease incentives. Lease expense for future lease payments is recognized on a straight-line basis over the lease term. Collaboration Agreements The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC Topic 808, Collaborative Arrangements (" ASC 808"), to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of ASC 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC Topic 606, Revenue from Contracts with Customers (" ASC 606"). If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants. Revenue Recognition The Company enters into collaboration agreements which are within the scope of ASC 606 under which the Company may license or provide options to license certain development or product candidates and, in certain cases, may perform research and development services. The terms of these agreements may include payment of non-refundable, upfront fees, option exercise fees, development and commercial milestone payments and royalties on net sales of licensed products. Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for agreements determined to be within the scope of ASC 606, the Company performs the following five steps: (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. The Company then assesses whether each promised good or service is distinct. When the Company offers options for additional goods or services, such as an option to obtain a license, it evaluates whether such options are material rights that should be treated as separate performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each agreement that includes variable consideration, the Company evaluates the amount of potential payments and the likelihood that the payments will be received to estimate the amount expected to be received. The amount of variable consideration included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal of the cumulative revenue recognized will not occur in a future period. The Company recognizes as revenue the amount of the transaction price that it allocated to the respective performance obligation when or as each performance obligation is satisfied, either at a point in time or over time. If the performance obligation is satisfied over time, the Company recognizes revenue based on the use of an output or input method. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. For example, f or research and development services that are recognized over time, the Company measures its progress using an input method. The input methods used are based on the effort the Company expends or costs it incurs toward the satisfaction of its performance obligation. The Company estimates the amount of effort it expends, including the time it estimates it will take to complete the activities, or costs it incurs in a given period, relative to the estimated total effort or costs to satisfy the performance obligation. This results in a percentage that is multiplied by the transaction price to determine the amount of revenue recognized each period. If the estimates or judgements change over the course of the collaboration, they may affect the timing and amount of revenue that is recognized in the current and future periods. Upfront payments are recorded as contract liabilities within deferred revenue on the consolidated balance sheets until the Company performs its obligations under these agreements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. As of December 31, 2023, the Company had one collaboration, option and license agreement with UCB Biopharma SRL ("UCB"), which it entered into in December 2022. The accounting related to the collaboration agreement is outlined in Note 9, UCB Option and License Agreement. Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities and clinical trials as well as to manufacture research and development materials. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed or until it is no longer expected that the goods will be delivered or the services rendered. Costs incurred to obtain licenses are recognized as research and development expense as incurred if the technology licensed has no alternative future uses. The Company has entered into various research and development related contracts with parties both inside and outside of the United States. These agreements are cancellable, and related fees are recorded as research and development expenses as incurred. The Company records accrued liabilities and prepaid expenses for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities and prepaid expenses, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical estimates have not been materially different from the actual costs. Patent-Related Costs Patent-related costs incurred in connection with patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses in the accompanying consolidated statement of operations. Stock-Based Compensation The Company accounts for all stock-based awards granted to employees and non-employees as stock-based compensation expense at fair value in accordance with FASB ASC Topic 718, Compensation—Stock Compensation ("ASC 718"). For stock-based awards issued to employees, non-employees and members of the Company’s board of directors (the “Board”) for their services on the Board, the Company measures the estimated fair value of the stock-based award on the date of the grant. The Company recognizes compensation expense for those awards granted to employees and members of the Board over the requisite service period, which is generally the vesting period of the respective award. For non-employee awards, compensation expense is recognized as the services are provided, which is generally ratably over the vesting period. The Company issues stock-based awards with service-based vesting conditions and records the expense for these awards on a straight-line basis over the vesting period. To date, the Company has not issued any stock-based awards with performance or market-based vesting conditions. The Company accounts for forfeitures as they occur. The Company classifies stock-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary or service payments are classified. The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model, which requires inputs of subjective assumptions, including: (i) the expected volatility of the Company’s stock; (ii) the expected term of the award; (iii) the risk-free interest rate; (iv) expected dividends; and (v) the fair value of common stock. Due to the lack of Company-specific historical and implied volatility data, the Company determines the volatility for awards granted based on an analysis of reported data for a group of guideline publicly-traded companies that issued options with substantially similar terms. For this analysis, the Company selects companies with comparable characteristics including enterprise value, risk profiles, and with historical share price information sufficient to meet the expected life of the stock-based awards. The Company determines expected volatility using a weighted average of the historical volatilities of the guideline group of companies. The Company expects to continue to apply this process until such time as it has adequate historical data regarding the volatility of its own traded stock price. As permitted under ASC 718, the Company has elected to use the contractual term as the expected term for certain non-employee awards, on an award-by-award basis. For all other awards, the expected term of the Company’s stock options has been determined utilizing the “simplified” method whereby the expected term equals the average of the vesting term and the original contractual term of the option, on a weighted basis based on the vesting of each tranche. The Company utilizes this method as it has insufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for instruments with a term commensurate with the expected term assumption. The expected dividend yield is assumed to be zero as the Company has never paid dividends, and does not have current plans to pay any dividends on its common stock. Subsequent to the IPO, the fair value of the common stock underlying the Company's stock-based awards is the closing price of the Company's common stock on the date of grant. The grant date fair value of restricted stock units is estimated based on the fair value of the Company's underlying common stock on the date of grant. Foreign Currency The functional currency of the Company’s wholly owned foreign subsidiary in Australia is the U.S. dollar. Monetary assets and liabilities resulting from transactions denominated in currencies other than the functional currency are remeasured into the functional currency at exchange rates prevailing at the balance sheet date. Non-monetary assets and liabilities denominated in foreign currencies are measured using historical exchange rates prevailing at the date of the transaction and are not subsequently remeasured. Exchange gains or losses arising from foreign currency transactions are included in the determination of net loss. There were no material foreign currency gains or losses for the years ended December 31, 2023 and 2022. Income Taxes Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent that it believes based upon the weight of available evidence it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established. The Company accounts for uncertain tax positions recognized in the consolidated financial statements by prescribing a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. For the years ended December 31, 2023 and 2022, comprehensive loss consists of net loss and changes in unrealized losses on marketable securities. Common Stock Warrants The Company accounts for warrants to purchase shares of its common stock in accordance with the guidance in FASB ASC No. 480, Distinguishing Liabilities from Equity (ASC 480) and ASC No. 815, Derivatives and Hedging (ASC 815). The Company classifies warrants issued for the purchase of shares of its common stock as either equity or liability instruments based on an assessment of the specific terms and conditions of each respective contract. Such assessment includes determining whether the warrants are freestanding financial instruments or embedded in a host instrument, whether the warrants are liabilities within the scope of ASC 480, whether the warrants meet the definition of a derivative in ASC 815 and whether the warrants meet the requirements for equity classification pursuant to the indexation and equity classification criteria in ASC 815. The Company determines the classification for its warrants at the time of issuance and updates its assessment, as necessary. Warrants that meet all of the criteria for equity classification are recorded as a component of additional paid-in capital. Equity classified warrants are accounted for at fair value on the issuance date with no changes in fair value recognized after the issuance date. Net Loss per Share Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period. The calculation of weighted average number of common shares outstanding excludes shares of restricted common stock that are not vested but includes shares of common stock underlying pre-funded warrants. Diluted net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period, after giving consideration to the dilutive effect of potentially dilutive common shares. For purposes of this calculation, outstanding options to purchase shares of common stock, unvested shares of restricted common stock and potential shares issuable under the 2020 ESPP are considered potentially dilutive common shares. The Company has generated a net loss in all periods presented so the basic and diluted net loss per share are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements On August 5, 2020, the FASB issued ASU No. 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (ASU 2020-06). ASU 2020-06 simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. ASU 2020-06 eliminates the separation models for convertible debt with cash conversion features and convertible instruments with beneficial conversion features and simplifies the derivative scope exception guidance pertaining to equity classification of

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Restricted Cash	Restricted Cash As of December 31, 2023 and 2022, the Company had restricted cash of $0.4 million and $0.4 million, respectively, held as letters of credit for the benefit of its current landlord. The Company's Boston, Massachusetts sublease expires on January 31, 2026, and the related letter of credit of $0.4 million was classified within other non-current assets on the consolidated balance sheet as of December 31, 2023 and 2022.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities The Company did not hold any marketable securities as of December 31, 2023. The following is a summary of the Company's investment portfolio as of December 31, 2022 (in thousands): 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 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 years ended December 31, 2023 and 2022.

Fair Value of Financial Assets

Fair Value of Financial Assets	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets	Fair Value of Financial Assets The Company did not hold any financial assets measured at fair value on a recurring basis as of December 31, 2023. The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values as of December 31, 2022 (in thousands): 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 The Company estimates the fair value of its marketable securities classified as Level 2 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.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): December 31, 2023 2022 Computer equipment $ 689 $ 689 Office furniture and equipment 545 545 Laboratory equipment 359 309 Total property and equipment 1,593 1,543 Less: Accumulated depreciation (1,005) (572) Property and equipment, net $ 588 $ 971 Depreciation expense was $0.4 million and $0.4 million for the years ended December 31, 2023 and 2022, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consisted of the following (in thousands): December 31, 2023 2022 Accrued personnel-related expenses $ 3,716 $ 2,803 Accrued external research and development expenses 2,957 10,734 Accrued other expenses 743 2,313 Total accrued expenses $ 7,416 $ 15,850

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases In May 2021, the Company entered into a sublease agreement for office space located in Boston, Massachusetts. The sublease 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 (Note 3). This lease qualifies as an operating lease. At inception, the Company recorded an operating lease right-of-use asset and operating lease liability of $4.1 million. The following table summarizes the presentation of the operating lease in the Company’s consolidated balance sheets (in thousands): As of December 31, 2023 2022 Assets: Operating lease right-of-use assets $ 2,064 $ 2,901 Liabilities: Current operating lease liabilities $ 1,126 $ 1,005 Non-current portion of operating lease liabilities 1,369 2,495 Total lease liabilities $ 2,495 $ 3,500 The following table summarizes total lease costs recognized in the Company’s consolidated statements of operations (in thousands): For the year ended December 31, 2023 2022 Operating lease cost $ 1,102 $ 1,102 Variable lease costs 14 37 Total lease costs $ 1,116 $ 1,139 Variable lease costs were primarily related to operating expenses, taxes and insurance associated with the operating leases, which were assessed based on the Company’s proportionate share of such costs for the leased premises. As these costs are generally variable in nature, they were not included in the measurement of the operating lease right-of-use asset and related lease liability. Total lease costs are included as operating expenses in the Company’s consolidated statements of operations and comprehensive loss. Future lease payments under non-cancelable lease agreements as of December 31, 2023 were as follows (in thousands): Year Ended December 31, Future Lease 2024 $ 1,296 2025 1,321 2026 110 Total future lease payments $ 2,727 Less: interest (232) Present value of operating lease liabilities $ 2,495 The weighted average remaining lease term and weighted average incremental borrowing rate of the Company’s operating lease were as follows: As of December 31, 2023 2021 Weighted average remaining lease term (in years) 2.1 3.1 Weighted average incremental borrowing rate 9.0 % 9.0 % Legal Proceedings The Company, from time to time, may be party to litigation arising in the ordinary course of business. The Company was not subject to any material legal proceedings during the years ended December 31, 2023 and 2022, and no material legal proceedings are currently pending or threatened. Purchase Orders The Company has agreements with third parties for various services, including services related to research, preclinical and clinical operations and support, for which the Company is not contractually able to terminate for convenience to avoid future obligations to the vendors. Certain agreements provide for termination rights subject to termination fees or wind down costs. Under such agreements, the Company is contractually obligated to make certain payments to vendors, primarily to reimburse them for their unrecoverable outlays incurred prior to cancellation. The actual amounts the Company could pay in the future to the vendors under such agreements may differ from the purchase order amounts due to cancellation provisions. Indemnification Agreements The Company enters into indemnification agreements and agreements containing indemnification provisions in the ordinary course of business. Pursuant to these agreements, 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 any U.S. patent or any copyright or other intellectual property infringement claim by any third party with respect to the Company’s products. The term of these indemnification agreements is generally perpetual upon execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. Agreements The Company has entered into multiple agreements with third parties under which it may be obligated to make future development, regulatory and commercial milestone payments and royalty payments on future sales of specified product candidates. Payments under these agreements generally become due and payable upon achievement of such milestones and sales. When the achievement of these milestones or sales have not occurred, such contingencies are not recorded in the Company's financial statements.

UCB Option and License Agreemen

UCB Option and License Agreement	12 Months Ended
	Dec. 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 using an input method over the duration of the research services. During the year ended December 31, 2023, the Company recognized $2.4 million in collaboration revenue related to the Collaboration Agreement in the consolidated statement of operations. As of December 31, 2023, $2.6 million was included in deferred revenue in the consolidated balance sheet, of which $1.4 million was classified as current.

Common Stock and Preferred Stoc

Common Stock and Preferred Stock	12 Months Ended
	Dec. 31, 2023
Stockholders' Equity Note [Abstract]
Common Stock and Preferred Stock	Common Stock and Preferred Stock Reverse Stock Split On November 28, 2023, the Company filed a Certificate of Amendment to the Company's Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a 1-for-15 reverse stock split of its common stock. The Reverse Stock Split became effective at 5:00 p.m., Eastern Time, on November 28, 2023. As a result of the Reverse Stock Split, every 15 shares of the Company's issued and outstanding common stock were automatically reclassified into one validly issued, fully-paid and non-assessable share of common stock. Any fractional post-split shares as a result of the Reverse Stock Split were rounded down to the nearest whole post-split share. The Reverse Stock Split did not affect the number of authorized shares of common stock or the par value of the common stock. All share amounts and per share amounts disclosed in this Annual Report on Form 10-K have been restated to reflect the Reverse Stock Split on a retroactive basis in all periods presented. Common Stock In November 2021, the Company entered into an Open Market Sale Agreement, as amended ("2021 Sales Agreement") with Jefferies LLC ("Jefferies"), to provide for the offering, issuance and sale of up to an aggregate amount of $125.0 million of common stock from time to time in at-the-market offerings under its shelf registration and subject to the limitations thereof. The Company terminated the 2021 Sales Agreement in June 2023. During the year ended December 31, 2023, the Company issued and sold an aggregate of 952,794 shares under the 2021 Sales Agreement for aggregate net proceeds of $24.1 million, after deducting commissions and offering expenses payable by the Company. During the year ended December 31, 2022, the Company issued and sold an aggregate of 239,684 shares under the 2021 Sales Agreement for aggregate net proceeds of $9.6 million, after deducting commissions and offering expenses payable by the Company. In December 2023, the Company entered into an Open Market Sale Agreement (the "2023 Sales Agreement"), with Jefferies, to provide for the offering, issuance and sale of up to an aggregate amount of $75.0 million of common stock from time to time in at-the-market offerings. The 2023 Sales Agreement was terminated in January 2024. During the year ended December 31, 2023, the Company issued and sold an aggregate of 212,453 shares under the 2023 Sales Agreement for aggregate net proceeds of $4.0 million, after deducting commissions and offering expenses payable by the Company. As of December 31, 2023 and 2022, the authorized capital stock of the Company included 150,000,000 shares of common stock, $0.0001 par value, pursuant to the Amended and Restated Certificate of Incorporation effective upon the completion of the IPO. Holders of such shares of common stock have the exclusive right to vote for the election of the Company's directors and are entitled to one vote per share. In the event of the voluntary or involuntary liquidation, dissolution or winding up of the Company, the holders of common stock are entitled to a pro rata distribution of the Company's net assets. Dividends may be declared and paid to such holders only when, as, and if declared by the Board or an authorized committee thereof. A s of December 31, 2023, the Company did not hold any treasury shares. June 2023 Public Offering On June 21, 2023, the Company completed a public offering of: (i) an aggregate of 4,296,646 shares of its common stock at a public offering price of $14.25 per share, including the underwriters’ full exercise of their option to purchase 619,979 additional shares of common stock, and (ii) pre-funded warrants to purchase 470,000 shares of common stock at a public offering price of $14.2485 per share of common stock underlying the warrants. The purchase price per share for each pre-funded warrant represents the per share offering price for the common stock, less the $0.0015 per share exercise price for each underlying share. Total net proceeds generated from the offering were approximately $63.4 million, after deducting underwriting discounts, commissions and other offering expenses payable by the Company. The pre-funded warrants are exercisable at any time on or after the date of issuance at the option of the holder, subject to a beneficial ownership blocker that may limit exercisability. No holder may exercise any portion of the warrants that would cause either the aggregate number of shares of common stock beneficially owned by such holder, together with its affiliates, to exceed 9.99%, or the combined voting power of the securities beneficially owned by such holder, together with its affiliates, to exceed 9.99%. A holder of a pre-funded warrant may increase or decrease this percentage up to 19.99% by providing at least 61 days’ prior notice to the Company. The pre-funded warrants do not expire. The pre-funded warrants may be settled through either physical or net share settlement. Following the occurrence of certain fundamental transactions, the holders of the pre-funded warrants have the right to receive upon exercise of the warrants the same amount and kind of securities, cash, or property as they would have been entitled to receive if they had been holders of the common shares issuable under the warrants immediately prior to such transaction. In the event of certain fundamental transactions where the consideration payable to the holders of shares of common stock consists solely of cash and/or marketable securities, the pre-funded warrants will automatically be deemed to be exercised in full pursuant to a cashless exercise effective immediately prior to and contingent upon the consummation of such transaction. As of December 31, 2023, none of the pre-funded warrants had been exercised and all remain outstanding. The Company determined that the pre-funded warrants are freestanding financial instruments because they are both legally detachable and separately exercisable from the common stock sold in the offering. As such, the Company evaluated the pre-funded warrants to determine whether they represent instruments that require liability classification pursuant to the guidance in ASC 480. However, the Company concluded that the pre-funded warrants are not a liability within the scope of ASC 480 due to their characteristics. Further, the Company determined that the pre-funded warrants do not meet the definition of a derivative under ASC 815 because they do not meet the criteria regarding no or little initial net investment. Accordingly, the Company assessed the pre-funded warrants relative to the guidance in ASC No. 815-40, Contracts in Entity’s Own Equity , to determine the appropriate treatment. The Company concluded that the pre-funded warrants are both indexed to its own stock and meet all other conditions for equity classification. Accordingly, the Company has classified the pre-funded warrants as permanent equity. Shares Reserved for Future Issuance The Company had reserved the following shares of common stock for future issuance: December 31, 2023 2022 Shares reserved for exercise of outstanding stock options 666,163 588,919 Shares reserved for exercise of pre-funded warrants 470,000 — Shares reserved for future awards under the 2020 Stock Option and Incentive Plan 148,264 110,063 Shares reserved for future awards under the 2020 Employee Stock Purchase Plan 53,111 65,420 Shares reserved for vesting of restricted stock units 47,145 49,565 Total shares of authorized common stock reserved for future issuance 1,384,683 813,967 Preferred Stock As of December 31, 2023 and 2022, the Company was authorized to issue 10,000,000 shares of undesignated preferred stock, $0.0001 par value, in one or more series, and is authorized to fix the powers, designations, preferences and relative participating option or other rights thereof, including dividend rights, conversion rights, voting rights, redemption rights, liquidation preferences and the number of shares constituting any series, without any further vote or action by the Company's shareholders. As of December 31, 2023 and 2022, the Company had no shares of undesignated preferred stock issued or outstanding.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The total number of shares of common stock authorized for issuance under the 2020 Stock Option and Incentive Plan (the "2020 Plan") as of December 31, 2023 and December 31, 2022 wa s 661,240 sh ares and 496,632 shares, respectively. The total number of shares of common stock authorized for issuance under the 2017 Stock Incentive Plan (the "2017 Plan") as of December 31, 2023 and 2022 was 395,850 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. Stock options issued under the 2020 Plan and 2017 Plan expire ten years from the date of grant. Shares that expire, are terminated, surrendered or canceled under the 2020 Plan and 2017 Plan without having been fully exercised will be available for future awards. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for future awards. Upon stock option exercise, the Company issues new shares and delivers them to the participant. 2020 Employee Stock Purchase Plan Th e total s hares authorized for issuance under the 2020 Employee Stock Purchase Plan (the "2020 ESPP") as of December 31, 2023 and 2022 was 87,227 shares and 65,420 shares, respectively. During the years ended December 31, 2023 and 2022, the Company issued 24,690 and 9,425 shares, respectively, under the 2020 ESPP. Restricted Stock Units The following table summarizes the Company’s restricted stock unit activity: Shares Weighted Unvested as of December 31, 2022 49,565 $ 346.17 Issued 29,478 35.16 Vested (13,293) 389.53 Forfeited (18,605) 178.57 Unvested as of December 31, 2023 47,145 $ 202.27 As of December 31, 2023, total unrecognized compensation cost related to unvested restricted stock units was $6.2 million, which is expected to be recognized over a weighted-average period of 1.81 years. Stock Options The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2022 588,919 $ 208.90 Granted 210,998 39.68 Exercised (3,281) 30.98 $ 90 Cancelled or Forfeited (130,473) 188.58 Outstanding as of December 31, 2023 666,163 $ 160.19 7.79 $ 254 Exercisable as of December 31, 2023 375,449 $ 189.20 7.25 $ 96 Vested and expected to vest as of December 31, 2023 666,163 $ 160.19 7.79 $ 254 The aggregate intrinsic value of stock options exercised for the years ended December 31, 2023 and 2022 was $0.1 million and $0.2 million, respectively. The aggregate intrinsic value of stock options outstanding, exercisable, and vested and expected to vest is calculated as the difference between the exercise price of the underlying stock options and the estimated fair value of the Company’s common stock for those stock options that had exercise prices lower than the estimated fair value of the Company’s common stock at December 31, 2023. The aggregate intrinsic value of stock options exercised is calculated as the difference between the exercise price of the underlying stock options and the estimated fair value of the Company’s common stock on the date of exercise for those stock options that had exercise prices lower than the fair value of the Company’s common stock on the exercise date. 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, members of the Board, and non-employees on the date of grant were as follows for the for the years ended December 31, 2023 and 2022: Year Ended December 31, 2023 2022 Risk-free interest rate 3.60 % 2.52 % Expected term (in years) 6.00 6.07 Expected volatility 88.40 % 89.20 % Expected dividend yield — % — % Weighted average grant-date fair value per share $ 29.73 $ 99.75 As of December 31, 2023, total unrecognized compensation cost related to unvested stock options was $24.0 million, which is expected to be recognized over a weighted-average period of 1.51 years. Stock-Based Compensation Stock-based compensation expense was allocated as follows (in thousands): Year Ended December 31, 2023 2022 Research and development $ 8,055 $ 9,972 General and administrative 16,802 18,621 Total stock-based compensation expense $ 24,857 $ 28,593

Significant Agreements

Significant Agreements	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Significant Agreements	Significant Agreements RogCon and Ionis Agreements On September 11, 2019, the Company entered into both a Cooperation and License Agreement (the “License Agreement”) with RogCon, Inc. ("RogCon"), and a Research, Collaboration, Option and License Agreement (the “Ionis Collaboration Agreement”) with Ionis Pharmaceuticals, Inc. ("Ionis"). The agreements were entered into contemporaneously to enable the parties to advance their collective efforts related to SCN2A. RogCon Agreement 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. Under the License Agreement, the Company will conduct, at its own cost and expense, the research and development activities assigned to it under the 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. As part of the agreement, the Company agreed to provide up-front consideration of $2.1 million. Subsequent to September 11, 2019, the Company will reimburse RogCon for its out-of-pocket costs incurred for activities performed under the License Agreement. The Company expenses these costs as incurred as research and development. Expenses incurred for all periods presented were not material. Additionally, the Company may pay RogCon a milestone payment of $3.0 million and profit share payments. The $3.0 million milestone payment will become due when the first profit share payment has become due and certain contingent payments have become payable to Ionis under the Ionis Collaboration Agreement, which are subject to the Company exercising its option to obtain license rights to a development candidate, as well as other contingent events. The profit share payments will be based on a low-double-digit percentage of net profits, depending on sales volume. The License Agreement, unless earlier terminated, will continue until the latest of: (i) expiration of all patent rights within RogCon patents, (ii) the Company and its affiliates certify they have abandoned the research, development and commercialization of product with no intention to re-establish such activities, and (iii) no third party is obligated to pay the Company or its affiliates any amounts that comprise net sublicense revenue. Either party may terminate the License Agreement for material breach or insolvency of the other party. Additionally, the Company may terminate for convenience with prior written notice to RogCon. Upon termination by either party, all rights and licenses granted by RogCon to the Company will revert back to RogCon. Ionis Collaboration Agreement Under the Ionis Collaboration Agreement, both parties participated in research activities related to the downregulation of SCN2A gene products associated with the treatment of any and all forms of epilepsy and/or neurodevelopmental disorders in each case caused by any mutation of the SCN2A gene, other than one severe type of epilepsy. Ionis was also responsible for identifying a development candidate and conducting an IND-enabling toxicology study. The Company reimbursed Ionis for out-of-pocket costs incurred related to the research activities, identification of a development candidate and conducting an IND-enabling toxicology study. The reimbursement of out-of-pocket costs was recognized as research and development expense as incurred. The Company expensed a total of $0.7 million as research and development expense under the Ionis Collaboration Agreement for the year ended December 31, 2022. Expense for the year ended December 31, 2023 was immaterial. Ionis granted the Company an exclusive option to obtain the rights and license to further develop and commercialize a development candidate in the field of epilepsy and neurodevelopmental disorders, other than Dravet Syndrome, following the results of the investigational new drug application-enabling toxicology study. The Company exercised this exclusive option in January 2022, paid a $2.0 million license fee and recognized the license fee in research and development expenses in the consolidated statement of operations during the year ended December 31, 2022. After option exercise, the Company is responsible for clinical development and commercialization of the development candidate. Additionally, in July 2023, the Company paid a milestone payment of $6.9 million to Ionis, which was earned in the second quarter of 2023 upon initiation of the Company's PRAX-222 EMBRAVE study, and was recognized in research and development expenses in the consolidated statement of operations during the year ended December 31, 2023. Ionis may be entitled to additional development milestone payments, additional milestone payments, and sales royalties or sublicense fees. The Ionis Collaboration Agreement will continue until the expiration of all payment obligations to Ionis, unless earlier terminated. Either party may terminate the Ionis Collaboration Agreement upon material breach or insolvency of the other party. Ionis may terminate if the Company fails to achieve a performance milestone. The Company may terminate for convenience with prior written notice to Ionis. Upon termination by the Company for convenience, the Company will stop selling all products, subject to certain wind-down provisions, and all products will revert back to Ionis.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss per Share	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: Year Ended December 31, 2023 2022 Outstanding stock options 666,163 588,919 Unvested restricted stock units 47,145 49,565 Potential shares issuable under the ESPP 24,972 18,924 738,280 657,408 Common shares issuable upon exercise of the pre-funded warrants that were sold in connection with the June 2023 underwritten public offering are included in the calculation of weighted average number of common shares outstanding for the year ended December 31, 2023. Consistent with the guidance in ASC 260-10-45-13, the underlying common shares are issuable for little to no consideration and there are no vesting conditions or contingencies associated with the warrants. Accordingly, the aggregate number of common shares underlying the pre-funded warrants have been considered outstanding for purposes of the calculation of net loss per share from the date of issuance.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company maintains a full valuation allowance on its U.S. net deferred tax assets due to the uncertainty of future taxable income. The Company did not recognize an income tax benefit in the years ended December 31, 2023 or 2022 related to its U.S. operations due to the uncertainty regarding future taxable income. In the years ended December 31, 2023 and 2022, the difference between the statutory tax rate in the U.S. and the Company’s effective tax rate was due primarily to the valuation allowance recorded to offset any potential tax benefit. The income tax benefit (provision) recognized for the years ended December 31, 2023 and 2022 was not material. The reconciliation of the U.S. statutory income tax rate to the Company’s effective tax rate is as follows: Year Ended December 31, 2023 2022 Federal statutory income tax rate 21.0 % 21.0 % Federal and state research and development credits 3.5 % 3.7 % State taxes, net of federal benefit 4.3 % 4.2 % Changes in tax rates 2.9 % — % Non-deductible items (1.4) % (0.7) % Stock-based compensation (1.3) % (1.0) % Change in valuation allowance (29.7) % (27.2) % Other 0.7 % — % Effective income tax rate — % — % Net deferred tax assets consisted of the following (in thousands): December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 74,528 $ 60,047 Capitalized research expenditures 48,954 34,947 Amortization 23,929 24,262 Research and development credits 23,451 17,205 Stock-based compensation 7,697 6,422 Accrued expenses 1,147 893 Deferred revenue 692 — Leases 676 898 Total gross deferred tax assets $ 181,074 $ 144,674 Less: Valuation allowance (180,515) (143,930) Net deferred tax assets $ 559 $ 744 Deferred tax liabilities: Operating lease right-of-use asset (559) (744) Total gross deferred tax liabilities (559) (744) Net deferred tax assets $ — $ — As of December 31, 2023 and 2022, the Company had U.S. federal net operating loss carryforwards which may be able to offset future income tax liabilities of approximately $282.8 million and $226.3 million, respectively. Federal net operating loss carryforwards of $7.7 million will expire at various dates from 2035 through 2037 and approximately $275.1 million may be carried forward indefinitely. As of December 31, 2023 and 2022, the Company also had state net operating loss carryforwards of approximately $239.4 million and $197.4 million, respectively, which may be available to offset future income tax liabilities and expire at various dates from 2036 through 2043. As of December 31, 2023 and 2022, the Company had federal research and development tax credit carryforwards of approximately $20.4 million and $14.4 million, respectively, available to reduce future tax liabilities which expire at various dates from 2039 through 2043. As of December 31, 2023 and 2022, the Company had state research and development tax credit carryforwards of approximately $3.8 million and $3.5 million, respectively, available to reduce future tax liabilities which expire at various dates from 2031 through 2038. The Company has generated research credits but has not conducted a study to document the qualified activity. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed, and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. If the Company has experienced a change of control, as defined by Section 382, at any time since inception, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, and then could be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. Further, until a study is completed by the Company and any limitation is known, no amounts are being presented as an uncertain tax position. ASC 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of the evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all of the evidence, both positive and negative, the Company has recorded a valuation allowance against its deferred tax assets at December 31, 2023 and 2022 because management has determined that it is more likely than not that the Company will not recognize the benefits of its federal and state deferred tax assets, primarily due to its history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception. As a result, a valuation allowance of $180.5 million and $143.9 million has been established at December 31, 2023 and 2022, respectively. Management reevaluates the positive and negative evidence at each reporting period. The valuation allowance increased by approximately $36.6 million and $58.0 million during the years ended December 31, 2023 and 2022, respectively, due primarily to the generation of net operating losses.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsOne of the founders of RogCon is the Company's General Counsel. During the years ended December 31, 2023 and 2022, the Company reimbursed RogCon for its out-of-pocket costs incurred for activities performed under the License Agreement (Note 12).

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan The Company has a defined contribution savings plan under Section 401(k) of the Internal Revenue Code for eligible employees. The plan covers substantially all employees who meet a minimum age requirement and allows participants to defer a portion of their annual compensation on a pre-tax basis. Under the plan, the Company is not obligated to match any participant contributions. The Company made contributions of $1.0 million and $1.5 million during the years ended December 31, 2023 and 2022, respectively .

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In June 2022, the Company began a strategic realignment across the Cerebrum™ and Solidus™ platforms, which resulted in a reduction of the Company's workforce. research and development expenses general and administrative expenses

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the 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 other than those noted below. Collaboration and License Agreement with Tenacia Biotechnology On January 4, 2024, the Company entered into an exclusive collaboration and license agreement (the "Collaboration Agreement") with Tenacia Biotechnology (Shanghai) Company, Ltd. ("Tenacia"), a China-based portfolio company of Bain Capital focused on central nervous system drug development and commercialization. Under the Collaboration Agreement, Tenacia will develop and commercialize ulixacaltamide for the treatment of essential tremor in Greater China. As part of the consideration for the Collaboration Agreement, the Company entered into a Stock Purchase Agreement (the "Stock Purchase Agreement") with BCPE Tenet Holdings Cayman, Ltd. ("BCPE") pursuant to which the Company issued and sold 443,253 shares of the Company's common stock, par value $0.0001 per share (the "Shares"), to BCPE at a price per share of $22.5605 for an aggregate purchase price of approximately $10.0 million. The per share price was based on a 20% premium over the 30-day volume-weighted average price. Additionally, the Company received an upfront payment of $5.0 million in cash, and is eligible for an additional $264.0 million in development, regulatory and commercialization milestone payments as well as tiered royalties on net sales. January 2024 Financing On January 12, 2024, the Company completed a public offering of: (i) an aggregate of 3,802,025 shares of its common stock at a public offering price of $35.50 per share, including the underwriters' full exercise of their option to purchase 633,750 additional shares of common stock, and (ii) pre-funded warrants to purchase 1,056,725 shares of common stock at a public offering price of $35.4999 per share of common stock underlying the warrants. The purchase price per share for each pre-funded warrant represents the per share offering price for the common stock, less the $0.0001 per share exercise price of each underlying share. Total net proceeds generated from the offering were approximately $161.7 million, after deducting underwriting discounts, commissions and other offering expenses payable by the Company. At-the-Market Offerings

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net loss	$ (26,878)	$ (24,632)	$ (34,312)	$ (37,455)	$ (41,173)	$ (43,945)	$ (60,194)	$ (68,717)	$ (123,277)	$ (214,029)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying 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. On November 28, 2023, the Company filed a Certificate of Amendment to the Company's Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to effect a 1-for-15 reverse stock split of its common stock (the "Reverse Stock Split"). The Reverse Stock Split became effective at 5:00 p.m., Eastern Time, on November 28, 2023. As a result of the Reverse Stock Split, every 15 shares of the Company's issued and outstanding common stock were automatically reclassified into one validly issued, fully-paid and non-assessable share of common stock. Any fractional post-split shares as a result of the Reverse Stock Split were rounded down to the nearest whole post-split share. The Reverse Stock Split did not affect the number of authorized shares of common stock or the par value of the common stock. All share amounts and per share amounts disclosed in this Annual Report on Form 10-K have been restated to reflect the Reverse Stock Split on a retroactive basis in all periods presented.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Praxis Security Corporation and Praxis Precision Medicines Australia Pty Ltd. All intercompany transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, accrued and prepaid research and development expense, 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.
Segments	Segments 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 purposes of assessing performance and allocating resources. The majority of the Company’s long-lived assets are held in the United States.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents. Cash and cash equivalents include cash held in banks and amounts held in interest-bearing insured liquid deposit funds. Cash equivalents are carried at cost, which approximates their fair market value. Restricted cash comprises letters of credit for the benefit of the landlord in connection with the Company’s lease facilities. Restricted cash is classified as either current or non-current based on the terms of the underlying lease arrangement.
Marketable Securities	Marketable Securities The Company may invest its excess cash in money market funds and debt instruments of the U.S. Treasury, financial institutions, corporations and U.S. government agencies with strong credit ratings and an investment grade rating at or above A-1 or P-1 by two of the three nationally recognized statistical rating organizations. The Company does not believe that it is exposed to more than a nominal amount of credit risk related to any marketable securities it may invest in. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity, and periodically reviews and modifies these guidelines to maximize trends in yields and interest rates without compromising safety and liquidity. The Company classifies its investments in debt instruments as available-for-sale. Available-for-sale investments are reported at fair value at each balance sheet date, and include any unrealized holding gains and losses in accumulated other comprehensive loss, a component of stockholders’ equity. Realized gains and losses are included in the Company's consolidated statements of operations. All of the Company's available-for-sale securities are available for use in its current operations. As a result, the Company has categorized all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. The Company did not hold any marketable securities as of December 31, 2023, and held $38.9 million of marketable securities as of December 31, 2022. The Company evaluates securities for impairment at the end of each reporting period. Impairment is evaluated considering numerous factors, and their relative significance varies depending on the situation. Factors considered include whether a decline in fair value below the amortized cost basis is due to credit-related factors or non-credit-related factors, the financial condition and near-term prospects of the Company, and the Company's intent and ability to hold the investment to allow for an anticipated recovery in fair value. A credit-related impairment is recognized as an allowance on the balance sheet with a corresponding adjustment to earnings. Any impairment that is not credit-related is recognized in other comprehensive loss, net of applicable taxes unless deemed other than temporary.
Concentrations of Credit Risk and Significant Suppliers and License Agreements	Concentrations of Credit Risk and Significant Suppliers and License Agreements Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents, restricted cash and marketable securities. The Company's investment portfolio may include money market funds, marketable debt securities, including debt securities issued by U.S. government agencies and corporations, and commercial paper. The Company investments are limited to investment-grade securities with strong credit ratings with the objective of maintaining safety and liquidity. The Company also maintains deposits in accredited financial institutions in excess of federally insured limits. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (the “FDIC”) up to $250,000. As of December 31, 2023 and 2022, the Company’s primary operating accounts significantly exceeded the FDIC limits. The Company deposits its cash in financial institutions that it believes have high credit quality, and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply materials for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relies, and expects to continue to rely, on a small number of third-party manufacturers to produce and process its current and potential product candidates and to manufacture supply of its current and potential product candidates for preclinical and clinical activities. These programs could be adversely affected by a significant interruption in the supply of the necessary materials. The Company is also dependent on third parties who provide license rights used in the development of certain programs. The Company could experience delays in the development of its programs if any of these license agreements are terminated, if the Company fails to meet the obligations required under its arrangements, or if the Company is unable to successfully secure new strategic alliances or licensing agreements.
Off-Balance Sheet Risk	Off-Balance Sheet Risk As of December 31, 2023 and 2022, the Company had no off-balance sheet risk such as foreign exchange contracts, option contracts or other hedging arrangements.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. The fair values of the Company’s financial assets and liabilities reflect the Company’s estimate of the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1: Quoted prices in active markets for identical assets or liabilities. • Level 2: Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3: Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. An entity may choose to measure many financial instruments and certain other items at fair value at specified election dates. Subsequent unrealized gains and losses on items for which the fair value option has been elected will be reported in earnings. Items measured at fair value on a recurring basis include cash equivalents and marketable securities (Note 4 and Note 5). The carrying amounts reflected in the consolidated balance sheets for cash, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the following estimated useful lives of the assets: Estimated Useful Life Office furniture and equipment 5 years Laboratory equipment 3 years Computer equipment 3 years Upon disposal, retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
Leases	Leases The Company accounts for leases in accordance with ASC 842. 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
Collaboration Agreements and Revenue Recognition	Collaboration Agreements The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC Topic 808, Collaborative Arrangements (" ASC 808"), to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of ASC 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC Topic 606, Revenue from Contracts with Customers (" ASC 606"). If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants. Revenue Recognition The Company enters into collaboration agreements which are within the scope of ASC 606 under which the Company may license or provide options to license certain development or product candidates and, in certain cases, may perform research and development services. The terms of these agreements may include payment of non-refundable, upfront fees, option exercise fees, development and commercial milestone payments and royalties on net sales of licensed products. Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for agreements determined to be within the scope of ASC 606, the Company performs the following five steps: (1) identify the contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when or as the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the Company will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. The Company then assesses whether each promised good or service is distinct. When the Company offers options for additional goods or services, such as an option to obtain a license, it evaluates whether such options are material rights that should be treated as separate performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each agreement that includes variable consideration, the Company evaluates the amount of potential payments and the likelihood that the payments will be received to estimate the amount expected to be received. The amount of variable consideration included in the transaction price may be constrained and is included in the transaction price only to the extent that it is probable that a significant reversal of the cumulative revenue recognized will not occur in a future period. The Company recognizes as revenue the amount of the transaction price that it allocated to the respective performance obligation when or as each performance obligation is satisfied, either at a point in time or over time. If the performance obligation is satisfied over time, the Company recognizes revenue based on the use of an output or input method. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. For example, f or research and development services that are recognized over time, the Company measures its progress using an input method. The input methods used are based on the effort the Company expends or costs it incurs toward the satisfaction of its performance obligation. The Company estimates the amount of effort it expends, including the time it estimates it will take to complete the activities, or costs it incurs in a given period, relative to the estimated total effort or costs to satisfy the performance obligation. This results in a percentage that is multiplied by the transaction price to determine the amount of revenue recognized each period. If the estimates or judgements change over the course of the collaboration, they may affect the timing and amount of revenue that is recognized in the current and future periods. Upfront payments are recorded as contract liabilities within deferred revenue on the consolidated balance sheets until the Company performs its obligations under these agreements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. As of December 31, 2023, the Company had one collaboration, option and license agreement with UCB Biopharma SRL ("UCB"), which it entered into in December 2022. The accounting related to the collaboration agreement is outlined in Note 9, UCB Option and License Agreement.
Research and Development Costs and Patent-Related Costs	Research and Development Costs Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities and clinical trials as well as to manufacture research and development materials. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed or until it is no longer expected that the goods will be delivered or the services rendered. Costs incurred to obtain licenses are recognized as research and development expense as incurred if the technology licensed has no alternative future uses. The Company has entered into various research and development related contracts with parties both inside and outside of the United States. These agreements are cancellable, and related fees are recorded as research and development expenses as incurred. The Company records accrued liabilities and prepaid expenses for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities and prepaid expenses, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical estimates have not been materially different from the actual costs. Patent-Related Costs Patent-related costs incurred in connection with patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses in the accompanying consolidated statement of operations.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for all stock-based awards granted to employees and non-employees as stock-based compensation expense at fair value in accordance with FASB ASC Topic 718, Compensation—Stock Compensation ("ASC 718"). For stock-based awards issued to employees, non-employees and members of the Company’s board of directors (the “Board”) for their services on the Board, the Company measures the estimated fair value of the stock-based award on the date of the grant. The Company recognizes compensation expense for those awards granted to employees and members of the Board over the requisite service period, which is generally the vesting period of the respective award. For non-employee awards, compensation expense is recognized as the services are provided, which is generally ratably over the vesting period. The Company issues stock-based awards with service-based vesting conditions and records the expense for these awards on a straight-line basis over the vesting period. To date, the Company has not issued any stock-based awards with performance or market-based vesting conditions. The Company accounts for forfeitures as they occur. The Company classifies stock-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary or service payments are classified. The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model, which requires inputs of subjective assumptions, including: (i) the expected volatility of the Company’s stock; (ii) the expected term of the award; (iii) the risk-free interest rate; (iv) expected dividends; and (v) the fair value of common stock. Due to the lack of Company-specific historical and implied volatility data, the Company determines the volatility for awards granted based on an analysis of reported data for a group of guideline publicly-traded companies that issued options with substantially similar terms. For this analysis, the Company selects companies with comparable characteristics including enterprise value, risk profiles, and with historical share price information sufficient to meet the expected life of the stock-based awards. The Company determines expected volatility using a weighted average of the historical volatilities of the guideline group of companies. The Company expects to continue to apply this process until such time as it has adequate historical data regarding the volatility of its own traded stock price. As permitted under ASC 718, the Company has elected to use the contractual term as the expected term for certain non-employee awards, on an award-by-award basis. For all other awards, the expected term of the Company’s stock options has been determined utilizing the “simplified” method whereby the expected term equals the average of the vesting term and the original contractual term of the option, on a weighted basis based on the vesting of each tranche. The Company utilizes this method as it has insufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for instruments with a term commensurate with the expected term assumption. The expected dividend yield is assumed to be zero as the Company has never paid dividends, and does not have current plans to pay any dividends on its common stock. Subsequent to the IPO, the fair value of the common stock underlying the Company's stock-based awards is the closing price of the Company's common stock on the date of grant. The grant date fair value of restricted stock units is estimated based on the fair value of the Company's underlying common stock on the date of grant.
Foreign Currency	Foreign Currency
Income Tax	Income Taxes Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent that it believes based upon the weight of available evidence it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established. The Company accounts for uncertain tax positions recognized in the consolidated financial statements by prescribing a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss and certain changes in stockholders’ equity that are excluded from net loss. For the years ended December 31, 2023 and 2022, comprehensive loss consists of net loss and changes in unrealized losses on marketable securities.
Common Stock Warrants	Common Stock Warrants The Company accounts for warrants to purchase shares of its common stock in accordance with the guidance in FASB ASC No. 480, Distinguishing Liabilities from Equity (ASC 480) and ASC No. 815, Derivatives and Hedging (ASC 815). The Company classifies warrants issued for the purchase of shares of its common stock as either equity or liability instruments based on an assessment of the specific terms and conditions of each respective contract. Such assessment includes determining whether the warrants are freestanding financial instruments or embedded in a host instrument, whether the warrants are liabilities within the scope of ASC 480, whether the warrants meet the definition of a derivative in ASC 815 and whether the warrants meet the requirements for equity classification pursuant to the indexation and equity classification criteria in ASC 815. The Company determines the classification for its warrants at the time of issuance and updates its assessment, as necessary. Warrants that meet all of the criteria for equity classification are recorded as a component of additional paid-in capital. Equity classified warrants are accounted for at fair value on the issuance date with no changes in fair value recognized after the issuance date.
Net Loss per Share	Net Loss per Share Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period. The calculation of weighted average number of common shares outstanding excludes shares of restricted common stock that are not vested but includes shares of common stock underlying pre-funded warrants. Diluted net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period, after giving consideration to the dilutive effect of potentially dilutive common shares. For purposes of this calculation, outstanding options to purchase shares of common stock, unvested shares of restricted common stock and potential shares issuable under the 2020 ESPP are considered potentially dilutive common shares. The Company has generated a net loss in all periods presented so the basic and diluted net loss per share are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements On August 5, 2020, the FASB issued ASU No. 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging – Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (ASU 2020-06). ASU 2020-06 simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. ASU 2020-06 eliminates the separation models for convertible debt with cash conversion features and convertible instruments with beneficial conversion features and simplifies the derivative scope exception guidance pertaining to equity classification of contracts in an entity’s own equity. Additionally, ASU 2020-06 amends the diluted earnings per share guidance, including the requirement to use the if-converted method for all convertible instruments. The new standard also introduces additional disclosures for convertible instruments. ASU 2020-06 was effective for public companies that are not smaller reporting companies for fiscal years beginning after December 15, 2021. For all other entities, ASU 2020-06 is effective for fiscal years beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020. ASU 2020-06 is required to be adopted as of the beginning of a fiscal year. ASU 2020-06 may be applied using either a full or modified retrospective method of transition. The Company adopted ASU 2020-06 effective as of January 1, 2023. The adoption of ASU 2020-06 did not have an impact on the Company’s financial statements. Recently Issued Accounting Pronouncements On November 27, 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures . ASU No. 2023-07 improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The amendments included in this ASU apply to all public entities that are required to report segment information in accordance with Topic 280, including those with a single reportable segment. The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted and should be applied retrospectively to all prior periods presented in the financial statements. Upon transition, the segment expenses categories and amounts disclosed in the prior periods should be based on the significant segment expense categories identified and disclosed in the period of adoption. The Company only has one reportable segment and this ASU impacts disclosures only. The Company has determined that the effects of adopting the amendments in ASU 2023-07 will only impact its disclosures and not have a material impact on its consolidated financial position and the results of its operations when such amendment is adopted. On December 14, 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures . ASU No. 2023-09 provides more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and incomes taxes paid information. For public companies, the amendments are effective for annual periods beginning after December 15, 2024 and should be applied prospectively. The Company has determined that the effects of adopting the amendments in ASU 2023-09 will only impact its disclosures and not have a material impact on its consolidated financial position and the results of its operations when such amendment is adopted.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Cash, Cash Equivalents and Restricted Cash	The following table presents cash and cash equivalents and restricted cash as reported on the consolidated balance sheets that equal the total amounts on the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 81,300 $ 61,615 Restricted cash 416 416 Total cash, cash equivalents and restricted cash as shown on the consolidated statements of cash flows $ 81,716 $ 62,031
Schedule of Restricted Cash and Cash Equivalents	The following table presents cash and cash equivalents and restricted cash as reported on the consolidated balance sheets that equal the total amounts on the consolidated statements of cash flows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 81,300 $ 61,615 Restricted cash 416 416 Total cash, cash equivalents and restricted cash as shown on the consolidated statements of cash flows $ 81,716 $ 62,031
Property, Plant and Equipment	Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the following estimated useful lives of the assets: Estimated Useful Life Office furniture and equipment 5 years Laboratory equipment 3 years Computer equipment 3 years Property and equipment, net consisted of the following (in thousands): December 31, 2023 2022 Computer equipment $ 689 $ 689 Office furniture and equipment 545 545 Laboratory equipment 359 309 Total property and equipment 1,593 1,543 Less: Accumulated depreciation (1,005) (572) Property and equipment, net $ 588 $ 971

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The following is a summary of the Company's investment portfolio as of December 31, 2022 (in thousands): 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 of Financial Assets

Fair Value of Financial Assets (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values as of December 31, 2022 (in thousands): 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

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the following estimated useful lives of the assets: Estimated Useful Life Office furniture and equipment 5 years Laboratory equipment 3 years Computer equipment 3 years Property and equipment, net consisted of the following (in thousands): December 31, 2023 2022 Computer equipment $ 689 $ 689 Office furniture and equipment 545 545 Laboratory equipment 359 309 Total property and equipment 1,593 1,543 Less: Accumulated depreciation (1,005) (572) Property and equipment, net $ 588 $ 971

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): December 31, 2023 2022 Accrued personnel-related expenses $ 3,716 $ 2,803 Accrued external research and development expenses 2,957 10,734 Accrued other expenses 743 2,313 Total accrued expenses $ 7,416 $ 15,850

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Consolidated Balance Sheets	The following table summarizes the presentation of the operating lease in the Company’s consolidated balance sheets (in thousands): As of December 31, 2023 2022 Assets: Operating lease right-of-use assets $ 2,064 $ 2,901 Liabilities: Current operating lease liabilities $ 1,126 $ 1,005 Non-current portion of operating lease liabilities 1,369 2,495 Total lease liabilities $ 2,495 $ 3,500
Lease cost	The following table summarizes total lease costs recognized in the Company’s consolidated statements of operations (in thousands): For the year ended December 31, 2023 2022 Operating lease cost $ 1,102 $ 1,102 Variable lease costs 14 37 Total lease costs $ 1,116 $ 1,139 The weighted average remaining lease term and weighted average incremental borrowing rate of the Company’s operating lease were as follows: As of December 31, 2023 2021 Weighted average remaining lease term (in years) 2.1 3.1 Weighted average incremental borrowing rate 9.0 % 9.0 %
Lessee, Operating Lease, Liability, Maturity	Future lease payments under non-cancelable lease agreements as of December 31, 2023 were as follows (in thousands): Year Ended December 31, Future Lease 2024 $ 1,296 2025 1,321 2026 110 Total future lease payments $ 2,727 Less: interest (232) Present value of operating lease liabilities $ 2,495

Common Stock and Preferred St_2

Common Stock and Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2023
Stockholders' Equity Note [Abstract]
Summary of common stock reserved for future issuance	The Company had reserved the following shares of common stock for future issuance: December 31, 2023 2022 Shares reserved for exercise of outstanding stock options 666,163 588,919 Shares reserved for exercise of pre-funded warrants 470,000 — Shares reserved for future awards under the 2020 Stock Option and Incentive Plan 148,264 110,063 Shares reserved for future awards under the 2020 Employee Stock Purchase Plan 53,111 65,420 Shares reserved for vesting of restricted stock units 47,145 49,565 Total shares of authorized common stock reserved for future issuance 1,384,683 813,967

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 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 Unvested as of December 31, 2022 49,565 $ 346.17 Issued 29,478 35.16 Vested (13,293) 389.53 Forfeited (18,605) 178.57 Unvested as of December 31, 2023 47,145 $ 202.27
Summary of stock option activity	The following table summarizes the Company’s stock option activity: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2022 588,919 $ 208.90 Granted 210,998 39.68 Exercised (3,281) 30.98 $ 90 Cancelled or Forfeited (130,473) 188.58 Outstanding as of December 31, 2023 666,163 $ 160.19 7.79 $ 254 Exercisable as of December 31, 2023 375,449 $ 189.20 7.25 $ 96 Vested and expected to vest as of December 31, 2023 666,163 $ 160.19 7.79 $ 254
Schedule of fair value of stock option awards on the grant date using the Black-Scholes option valuation model	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, members of the Board, and non-employees on the date of grant were as follows for the for the years ended December 31, 2023 and 2022: Year Ended December 31, 2023 2022 Risk-free interest rate 3.60 % 2.52 % Expected term (in years) 6.00 6.07 Expected volatility 88.40 % 89.20 % Expected dividend yield — % — % Weighted average grant-date fair value per share $ 29.73 $ 99.75
Summary of stock-based compensation expense	Stock-based compensation expense was allocated as follows (in thousands): Year Ended December 31, 2023 2022 Research and development $ 8,055 $ 9,972 General and administrative 16,802 18,621 Total stock-based compensation expense $ 24,857 $ 28,593

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Summary of antidilutive securities excluded from computation of earnings 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: Year Ended December 31, 2023 2022 Outstanding stock options 666,163 588,919 Unvested restricted stock units 47,145 49,565 Potential shares issuable under the ESPP 24,972 18,924 738,280 657,408

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the U.S. statutory income tax rate to the Company’s effective tax rate is as follows: Year Ended December 31, 2023 2022 Federal statutory income tax rate 21.0 % 21.0 % Federal and state research and development credits 3.5 % 3.7 % State taxes, net of federal benefit 4.3 % 4.2 % Changes in tax rates 2.9 % — % Non-deductible items (1.4) % (0.7) % Stock-based compensation (1.3) % (1.0) % Change in valuation allowance (29.7) % (27.2) % Other 0.7 % — % Effective income tax rate — % — %
Schedule of Deferred Tax Assets and Liabilities	Net deferred tax assets consisted of the following (in thousands): December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 74,528 $ 60,047 Capitalized research expenditures 48,954 34,947 Amortization 23,929 24,262 Research and development credits 23,451 17,205 Stock-based compensation 7,697 6,422 Accrued expenses 1,147 893 Deferred revenue 692 — Leases 676 898 Total gross deferred tax assets $ 181,074 $ 144,674 Less: Valuation allowance (180,515) (143,930) Net deferred tax assets $ 559 $ 744 Deferred tax liabilities: Operating lease right-of-use asset (559) (744) Total gross deferred tax liabilities (559) (744) Net deferred tax assets $ — $ —

Nature of the Business (Details

Nature of the Business (Details) $ in Thousands			1 Months Ended	2 Months Ended	3 Months Ended								12 Months Ended
	Jan. 12, 2024 USD ($)	Jun. 21, 2023 USD ($)	Jan. 30, 2024 USD ($)	Mar. 06, 2024 USD ($)	Dec. 31, 2023 USD ($) candidate platform	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) candidate platform	Dec. 31, 2022 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Number of platforms | platform					2								2
Number of product candidates | candidate					4								4
Proceeds from issuance of equity													$ 617,500
Net loss					$ 26,878	$ 24,632	$ 34,312	$ 37,455	$ 41,173	$ 43,945	$ 60,194	$ 68,717	123,277	$ 214,029
Accumulated deficit					653,921				$ 530,644				653,921	530,644
Cash, cash equivalents, and short-term investments					$ 81,300								81,300
Subsequent Event
Debt and Equity Securities, FV-NI [Line Items]
Sale of stock, gross proceeds			$ 5,300	$ 5,300
Follow-On Offering
Debt and Equity Securities, FV-NI [Line Items]
Proceeds from stock offerings, net of issuance costs		$ 63,400											$ 63,439	$ 0
Follow-On Offering | Subsequent Event
Debt and Equity Securities, FV-NI [Line Items]
Proceeds from stock offerings, net of issuance costs	$ 161,700		$ 161,700

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)		12 Months Ended
	Nov. 28, 2023	Dec. 31, 2023 USD ($) segment agreement	Dec. 31, 2022 USD ($)
Accounting Policies [Abstract]
Stock split, conversion ratio	0.0667
Number of operating segments | segment		1
Marketable securities		$ 0	$ 38,874,000
Impairment losses		$ 0	0
Number of collaboration, option, and license agreements | agreement		1
Expected dividend yield		0%
Foreign currency gain (loss)		$ 0	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 81,300	$ 61,615
Restricted cash	416	416
Total cash, cash equivalents and restricted cash as shown on the consolidated statements of cash flows	$ 81,716	$ 62,031	$ 139,720

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property and Equipment Estimated Useful Life (Details)	Dec. 31, 2023
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Computer equipment
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years

Restricted Cash (Details)

Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Restricted cash	$ 416	$ 416
Letters of credit receivable, noncurrent	$ 400	$ 400

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Marketable securities	$ 0	$ 38,874,000
Other-than-temporary impairment loss, debt securities, available-for-sale	$ 0	$ 0

Marketable Securities - Investm

Marketable Securities - Investment Profile (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, amortized cost, current		$ 39,047,000
Total available-for-sale securities, amortized cost		39,047,000
Available-for-sale, accumulated gross unrealized gain, current, before tax		0
Total available-for-sale securities, gross unrealized gains		0
Available-for-sale, accumulated gross unrealized loss, current, before tax		(173,000)
Total available-for-sale securities, gross unrealized losses		(173,000)
Estimated fair value, available-for-sale, current		38,874,000
Total available-for-sale securities, estimated fair value	$ 0	38,874,000
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, amortized cost, current		35,042,000
Available-for-sale, accumulated gross unrealized gain, current, before tax		0
Available-for-sale, accumulated gross unrealized loss, current, before tax		(163,000)
Estimated fair value, available-for-sale, current		34,879,000
Debt securities issued by U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, amortized cost, current		4,005,000
Available-for-sale, accumulated gross unrealized gain, current, before tax		0
Available-for-sale, accumulated gross unrealized loss, current, before tax		(10,000)
Estimated fair value, available-for-sale, current		$ 3,995,000

Fair Value of Financial Asset_2

Fair Value of Financial Assets - Summary of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	$ 73,055,000
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		38,176,000
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		34,879,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		34,181,000
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		34,181,000
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:		0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		34,879,000
Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		0
Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		34,879,000
Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		0
Debt securities issued by U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		3,995,000
Debt securities issued by U.S. government agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		3,995,000
Debt securities issued by U.S. government agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		0
Debt securities issued by U.S. government agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities:		$ 0

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,593	$ 1,543
Less: Accumulated depreciation	(1,005)	(572)
Property and equipment, net	588	971
Depreciation	432	419
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	689	689
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	545	545
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 359	$ 309

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued personnel-related expenses	$ 3,716	$ 2,803
Accrued external research and development expenses	2,957	10,734
Accrued other expenses	743	2,313
Total accrued expenses	$ 7,416	$ 15,850

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	May 31, 2021
Loss Contingencies [Line Items]
Operating lease right-of-use assets	$ 2,064	$ 2,901
Present value of operating lease liabilities	$ 2,495	$ 3,500
Office Space In Boston, Massachusetts
Loss Contingencies [Line Items]
Percentage increase in annual base rent			2%
Operating lease right-of-use assets			$ 4,100
Present value of operating lease liabilities			$ 4,100

Commitments and Contingencies_2

Commitments and Contingencies - Operating Lease, Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease right-of-use assets	$ 2,064	$ 2,901
Current operating lease liabilities	1,126	1,005
Non-current portion of operating lease liabilities	1,369	2,495
Total lease liabilities	$ 2,495	$ 3,500

Commitments and Contingencies_3

Commitments and Contingencies - Total Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,102	$ 1,102
Variable lease costs	14	37
Total lease costs	$ 1,116	$ 1,139

Commitments and Contingencies_4

Commitments and Contingencies - Future Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2024	$ 1,296
2025	1,321
2026	110
Total future lease payments	2,727
Less: interest	(232)
Total lease liabilities	$ 2,495	$ 3,500

Commitments and Contingencies_5

Commitments and Contingencies - Weighted Average Remaining Lease Term and Weighted Average Incremental Borrowing Rate (Details)	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Weighted average remaining lease term (in years)	2 years 1 month 6 days	3 years 1 month 6 days
Weighted average incremental borrowing rate	9%	9%

UCB Option and License Agreem_2

UCB Option and License Agreement (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) obligation
Disaggregation of Revenue [Line Items]
Number of performance obligations | obligation		1
Collaboration revenue	$ 2,447	$ 0
Current portion of deferred revenue	1,392	2,818
UCB | License
Disaggregation of Revenue [Line Items]
Upfront payment	2,600	5,000
Milestone payments		98,500
Upfront payment		$ 5,000
Collaboration revenue	2,400
Current portion of deferred revenue	$ 1,400

Common Stock and Preferred St_3

Common Stock and Preferred Stock - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	Nov. 28, 2023	Jun. 21, 2023 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) vote $ / shares shares	Nov. 30, 2021 USD ($)	Dec. 31, 2023 USD ($) vote $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Stock split, conversion ratio	0.0667
Common stock, authorized (in shares)			150,000,000		150,000,000	150,000,000
Common stock, par value (in USD per share) | $ / shares			$ 0.0001		$ 0.0001	$ 0.0001
Number of votes per share | vote			1		1
Treasury shares (in shares)			0		0
Preferred stock, authorized (in shares)			10,000,000		10,000,000	10,000,000
Preferred stock, par value (in USD per share) | $ / shares			$ 0.0001		$ 0.0001	$ 0.0001
Preferred stock, issued (in shares)			0		0	0
Preferred stock, outstanding (in shares)			0		0	0
Pre-Funded Warrant | Maximum
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Percentage of ownership held by sole owner					9.99%
Change in percentage of ownership					19.99%
Warrant
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Notice of change, term					61 days
2021 Sales Agreement
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Shares sold in follow-on public offering (in shares)					952,794	239,684
Proceeds from stock offerings, net of issuance costs | $					$ 24,100	$ 9,600
2023 Sales Agreement
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Shares sold in follow-on public offering (in shares)					212,453
Proceeds from stock offerings, net of issuance costs | $					$ 4,000
Sale of stock, aggregate authorized amount | $			$ 75,000
Follow-On Offering
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Sale of stock, net of discounts, commissions and offering expenses | $				$ 125,000
Proceeds from stock offerings, net of issuance costs | $		$ 63,400			$ 63,439	$ 0
Common stock, authorized (in shares)		4,296,646
Sale of stock, price (in USD per share) | $ / shares		$ 14.25
Follow-On Offering | Pre-Funded Warrant
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Sale of stock, price (in USD per share) | $ / shares		$ 14.2485
Warrants (in shares)		470,000	470,000		470,000	0
Follow-On Offering | Warrant
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Class of warrant or right, exercise price of warrants or rights (in dollars per share) | $ / shares		$ 0.0015
Over-Allotment Option
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Shares sold in follow-on public offering (in shares)		619,979

Common Stock and Preferred St_4

Common Stock and Preferred Stock - Summary of Common Stock Reserved For Future Issuance (Details) - shares	Dec. 31, 2023	Jun. 21, 2023	Dec. 31, 2022
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Total shares of authorized common stock reserved for future issuance (in shares)	1,384,683		813,967
Pre-Funded Warrant | Follow-On Offering
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Warrants (in shares)	470,000	470,000	0
Stock Options
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Total shares of authorized common stock reserved for future issuance (in shares)	666,163		588,919
Future Share-based Awards | 2020 Employee Stock Incentive Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Total shares of authorized common stock reserved for future issuance (in shares)	148,264		110,063
Future Share-based Awards | 2020 Employee Stock Purchase Plan
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Total shares of authorized common stock reserved for future issuance (in shares)	53,111		65,420
Restricted Stock
Schedule Of Common Stock Reserved For Future Issuance [Line Items]
Total shares of authorized common stock reserved for future issuance (in shares)	47,145		49,565

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value exercised	$ 90	$ 200
Unvested Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested restricted stock units	$ 6,200
Unrecognized compensation expense expected to be recognized	1 year 9 months 21 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense expected to be recognized	1 year 6 months 3 days
Unrecognized compensation expense related to unvested stock based awards	$ 24,000
2020 Employee Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	661,240	496,632
Award expiration period	10 years
2017 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	395,850	395,850
Award expiration period	10 years
2020 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	87,227	65,420
Issuance of common stock under employee stock purchase plan (in shares)	24,690	9,425

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Shares
Beginning balance (in shares) | shares	49,565
Issued (in shares) | shares	29,478
Vested (in shares) | shares	(13,293)
Forfeited (in shares) | shares	(18,605)
Ending balance (in shares) | shares	47,145
Weighted Average Grant Date Fair Value
Weighted average grant date fair value beginning balance (in dollars per share) | $ / shares	$ 346.17
Issued (in dollars per share) | $ / shares	35.16
Vested (in dollars per share) | $ / shares	389.53
Forfeited (in dollars per share) | $ / shares	178.57
Weighted average grant date fair value ending balance (in dollars per share) | $ / shares	$ 202.27

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Shares
Number of shares outstanding beginning balance (in shares)	588,919
Number of shares granted (in shares)	210,998
Number of shares exercised (in shares)	(3,281)
Number of shares canceled or forfeited (in shares)	(130,473)
Number of shares outstanding ending balance (in shares)	666,163	588,919
Number of shares exercisable (in shares)	375,449
Number of shares vested and expected to vest (in shares)	666,163
Weighted Average Exercise Price per Share
Weighted average exercise price beginning balance (in dollars per share)	$ 208.90
Weighted average exercise price granted (in dollars per share)	39.68
Weighted average exercise price exercised (in dollars per share)	30.98
Weighted average exercise price cancelled or forfeited (in dollars per share)	188.58
Weighted average exercise price ending balance (in dollars per share)	160.19	$ 208.90
Weighted average exercise price exercisable (in dollars per share)	189.20
Weighted average exercise price vested and expected to vest (in dollars per share)	$ 160.19
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term outstanding	7 years 9 months 14 days
Weighted average remaining contractual term exercisable	7 years 3 months
Weighted average remaining contractual term vested and expected to vest	7 years 9 months 14 days
Aggregate intrinsic value exercised	$ 90	$ 200
Aggregate intrinsic value outstanding	254
Aggregate intrinsic value exercisable	96
Aggregate intrinsic value vested and expected to vest	$ 254

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Fair Value of Stock Option Awards on the Grant Date Using the Black-Scholes Option Valuation Model (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	3.60%	2.52%
Expected term (in years)	6 years	6 years 25 days
Expected volatility	88.40%	89.20%
Expected dividend yield	0%	0%
Weighted average grant-date fair value per share (in dollars per share)	$ 29.73	$ 99.75

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 24,857	$ 28,593
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	8,055	9,972
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 16,802	$ 18,621

Significant Agreements (Details

Significant Agreements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Jul. 31, 2023	Sep. 11, 2019
Other Commitments [Line Items]
Research and development expense	$ 86,766	$ 155,040
Ionis
Other Commitments [Line Items]
Research and development expense	0	700
License agreement | RogCon
Other Commitments [Line Items]
Commitment				$ 2,100
License agreement | Ionis
Other Commitments [Line Items]
Commitment		$ 2,000
License agreement, profit share payments | RogCon
Other Commitments [Line Items]
Commitment	$ 3,000
Milestone Payment | Ionis
Other Commitments [Line Items]
Commitment			$ 6,900

Net Loss per Share - Summary of

Net Loss per Share - Summary of antidilutive securities excluded from computation of earnings per share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	738,280	657,408
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	666,163	588,919
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	47,145	49,565
Potential shares issuable under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	24,972	18,924

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21%	21%
Federal and state research and development credits	3.50%	3.70%
State taxes, net of federal benefit	4.30%	4.20%
Changes in tax rates	2.90%	0%
Non-deductible items	(1.40%)	(0.70%)
Stock-based compensation	(1.30%)	(1.00%)
Change in valuation allowance	(29.70%)	(27.20%)
Other	0.70%	0%
Effective income tax rate	0%	0%

Income Taxes - Net Deferred Tax

Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 74,528	$ 60,047
Capitalized research expenditures	48,954	34,947
Amortization	23,929	24,262
Research and development credits	23,451	17,205
Stock-based compensation	7,697	6,422
Accrued expenses	1,147	893
Deferred revenue	692	0
Leases	676	898
Total gross deferred tax assets	181,074	144,674
Less: Valuation allowance	(180,515)	(143,930)
Net deferred tax assets	559	744
Deferred tax liabilities:
Operating lease right-of-use asset	(559)	(744)
Total gross deferred tax liabilities	(559)	(744)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, domestic	$ 282,800	$ 226,300
Operating loss carryforwards, subject to expiration	7,700
Operating loss carryforwards, not subject to expiration	275,100
Operating loss carryforwards, state and local	239,400	197,400
Research and development credits	23,451	17,205
Valuation allowance	180,515	143,930
Valuation allowance, increase (decrease), amount	36,600	58,000
Federal
Operating Loss Carryforwards [Line Items]
Research and development credits	20,400	14,400
State
Operating Loss Carryforwards [Line Items]
Research and development credits	$ 3,800	$ 3,500

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Defined contribution plan, employer discretionary contribution amount	$ 1	$ 1.5

Restructuring (Details)

Restructuring (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1
Research and Development Expense
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0.6
Restructuring, Incurred Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Research and development
General and Administrative Expense
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0.4
Restructuring, Incurred Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	General and administrative

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended	2 Months Ended	12 Months Ended
	Jan. 12, 2024	Jan. 04, 2024	Jun. 21, 2023	Jan. 30, 2024	Mar. 06, 2024	Dec. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Common stock, par value (in USD per share)						$ 0.0001	$ 0.0001
Follow-On Offering
Subsequent Event [Line Items]
Sale of stock, price (in USD per share)			$ 14.25
Proceeds from stock offerings, net of issuance costs			$ 63,400			$ 63,439	$ 0
Follow-On Offering | Pre-Funded Warrant
Subsequent Event [Line Items]
Sale of stock, price (in USD per share)			$ 14.2485
Warrants (in shares)			470,000			470,000	0
Follow-On Offering | Warrant
Subsequent Event [Line Items]
Class of warrant or right, exercise price of warrants or rights (in dollars per share)			$ 0.0015
Over-Allotment Option
Subsequent Event [Line Items]
Shares sold in follow-on public offering (in shares)			619,979
Subsequent Event
Subsequent Event [Line Items]
Shares sold in follow-on public offering (in shares)					192,190
Sale of stock, gross proceeds				$ 5,300	$ 5,300
Subsequent Event | Tenacia
Subsequent Event [Line Items]
Shares sold in follow-on public offering (in shares)		443,253
Common stock, par value (in USD per share)		$ 0.0001
Sale of stock, price (in USD per share)		$ 22.5605
Proceeds from stock offerings, net of issuance costs		$ 10,000
Sale of stock, volume-weighted average price, premium		20%
Sale of stock, volume-weighted average price, duration		30 days
Subsequent Event | Tenacia | License
Subsequent Event [Line Items]
Upfront payment		$ 5,000
Milestone payments		$ 264,000
Subsequent Event | Follow-On Offering
Subsequent Event [Line Items]
Sale of stock, price (in USD per share)	$ 35.50
Proceeds from stock offerings, net of issuance costs	$ 161,700			$ 161,700
Sale of stock, shares, aggregate authorized amount (in shares)	3,802,025
Subsequent Event | Follow-On Offering | Pre-Funded Warrant
Subsequent Event [Line Items]
Sale of stock, price (in USD per share)	$ 35.4999
Warrants (in shares)	1,056,725
Subsequent Event | Follow-On Offering | Warrant
Subsequent Event [Line Items]
Class of warrant or right, exercise price of warrants or rights (in dollars per share)	$ 0.0001
Subsequent Event | Over-Allotment Option
Subsequent Event [Line Items]
Shares sold in follow-on public offering (in shares)	633,750