eFFECTOR Therapeutics (EFTR) 10-K 26 Mar 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 29, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	eFFECTOR Therapeutics, Inc.
Entity Central Index Key	0001828522
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 51.3
Entity Common Stock, Shares Outstanding		3,687,309
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity File Number	001-39866
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-3306396
Entity Address, Address Line One	142 North Cedros Avenue
Entity Address, Address Line Two	Suite B
Entity Address, City or Town	Solana Beach
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92075
City Area Code	858
Local Phone Number	925-8215
Document Annual Report	true
Document Transition Report	false
Document Financial Statement Error Correction [Flag]	false
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42
Common Stock [Member]
Document Information [Line Items]
Trading Symbol	EFTR
Title of 12(b) Security	Common stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Warrant [Member]
Document Information [Line Items]
Trading Symbol	EFTRW
Title of 12(b) Security	Warrants to purchase common stock
Security Exchange Name	NASDAQ

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents		$ 14,875	$ 8,708
Short-term investments		3,495	17,602
Prepaid expenses and other current assets		1,468	1,704
Total current assets		19,838	28,014
Property and equipment, net		140	241
Operating lease right-of-use assets		53	111
Other assets		513	711
Total assets		20,544	29,077
Current liabilities:
Accounts payable		2,330	1,486
Accrued expenses		2,921	3,368
Current term loans, net		19,385	19,061
Accrued final payment on term loans, current		1,100	1,100
Operating lease liabilities, current		60	60
Total current liabilities		25,796	25,075
Other accrued liabilities, non-current		503	0
Earn-out liability		0	6
Non current warrant liability		40	40
Non-current lease liabilities		0	60
Total liabilities		26,339	25,181
Commitments and contingencies
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value; 100,000,000 and zero shares authorised at December 31, 2023 and December 31, 2022, respectively; zero shares issued and outstanding as of December 31, 2023 and December 31,2022		0	0
Common stock, $0.0001 par value; 1,000,000,000 shares authorized at December 31, 2023 and December 31, 2022; 41,990,383 shares issued and 41,690,383 shares issued and outstanding as of December 31, 2023; 40,689,975 shares issued and 40,3389,975 shares issued and outstanding as of December 31, 2022	[1]	0	0
Additional paid-in capital	[1]	173,582	147,480
Accumulated other comprehensive loss		0	(18)
Accumulated deficit		(179,377)	(143,566)
Total stockholders' equity (deficit)		(5,795)	3,896
Total liabilities and stockholders' equity (deficit)		$ 20,544	$ 29,077
[1] Amounts have been retroactively restated to reflect the 1-for-25 reverse stock split effected on January 12, 2024 (see Note 1. Organization and Basis of Presentation of the accompanying notes to the consolidated financial statements).

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock price per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	2,994,679	1,679,602
Common stock, shares outstanding	2,982,679	1,667,602

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Grant revenue	$ 0	$ 3,553
Operating expenses:
Research and development	22,919	23,313
General and administrative	10,925	12,643
Total operating expenses	33,844	35,956
Operating (loss) income	(33,844)	(32,403)
Other income (expense)
Interest income	972	439
Interest expense	(2,919)	(2,251)
Other income (expense), net	(26)	(574)
Change in fair value of earn-out liability	6	12,124
Total other income (expense)	(1,967)	9,738
Net income (loss)	(35,811)	(22,665)
Comprehensive income (loss):
Net loss	(35,811)	(22,665)
Other comprehensive loss	18	(18)
Comprehensive income (loss):	$ (35,793)	$ (22,683)
Net income (loss) per share attributable to common shareholders:
Net income per share - Basic	$ (16.37)	$ (13.76)
Net income per share - diluted	$ (16.37)	$ (13.76)
Weighted-average common shares outstanding:
Weighted average common shares outstanding - basic	2,186,954	1,647,183
Weighted average common shares outstanding - diluted	2,186,954	1,647,183

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands		Total	Common Stock [Member]		Additional Paid-in Capital [Member]	[1]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2021		$ 17,284	$ 0	[1]	$ 138,185		$ 0	$ (120,901)
Balance, shares at Dec. 31, 2021	[1]		1,615,598
Stock option exercises, Value		3			3
Stock option exercises, Share	[1]		193
Issuance of common stock, net of issuance costs		3,958			3,958
Issuance of common stock, net of issuance costs, Share	[1]		51,811
Stock-based compensation expense		5,334			5,334
Unrealized loss on short-term investments		(18)					(18)
Net loss		(22,665)						(22,665)
Balance at Dec. 31, 2022		$ 3,896	$ 0	[1]	147,480		(18)	(143,566)
Balance, shares at Dec. 31, 2022		1,667,602	1,667,602	[1]
Issuance of Common Stock, Net of Issuance Costs Registered Direct Offerings, Value		$ 14,523			14,523
Issuance of common stock, net of issuance costs - Registered direct offerings, Shares	[1]		426,000
Exercise of prefunded warrants - Registered direct offerings, Value		8			8
Exercise of prefunded warrants - Registered direct offerings, Shares	[1]		342,593
Stock option exercises, Value		$ 47			47
Stock option exercises, Share		3,590	3,590	[1]
Issuance of common stock, net of issuance costs		$ 6,929			6,929
Issuance of common stock, net of issuance costs, Share	[1]		542,894
Stock-based compensation expense		4,595			4,595
Unrealized loss on short-term investments		18					18
Net loss		(35,811)						(35,811)
Balance at Dec. 31, 2023		$ (5,795)	$ 0	[1]	$ 173,582		$ 0	$ (179,377)
Balance, shares at Dec. 31, 2023		2,982,679	2,982,679	[1]
[1] Amounts have been retroactively restated to reflect the 1-for-25 reverse stock split effected on January 12, 2024 (see Note 1. Organization and Basis of Presentation of the accompanying notes to the consolidated financial statements).

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating activities:
Net loss	$ (35,811)	$ (22,665)
Adjustments to reconcile net income (loss) to cash used in operating activities:
Depreciation and amortization expense	111	53
Accretion of discount and amortization of premium on investments, net	(473)	(37)
Stock-based compensation	4,595	5,334
Loss (gain) on disposal of assets	(3)	1
Gain on change in fair value of warrant liability	0	(638)
Gain on change in fair value of earn-out liability	(6)	(12,124)
Other expense related to the equity purchase agreement	29	1,161
Non-cash interest expense	323	339
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	587	1,575
Other non-current assets	192	192
Accounts payable	855	958
Accrued expenses	52	(52)
Operating lease right-of-use assets and liabilities, net	(1)	4
Net cash used in operating activities	(29,550)	(25,899)
Investing activities:
Purchases of fixed assets	(97)	(192)
Maturities of short-term investments	31,750	34,750
Purchases of short-term investments	(17,169)	(52,418)
Net cash provided by (used in) investing activities	14,484	(17,860)
Financing activities:
Payment of debt issuance costs	0	(37)
Proceeds from exercise of common stock options and warrants	56	3
Proceeds from issuance of common stock - Registered direct offerings, net of issuance costs	14,523	0
Proceeds from issuance of common stock including ESPP, net of issuance costs	6,654	2,799
Net cash provided by financing activities	21,233	2,765
Net increase (decrease) in cash and cash equivalents	6,167	(40,994)
Cash and cash equivalents at beginning of period	8,708	49,702
Cash and cash equivalents at end of period	14,875	8,708
Supplemental disclosure of cash flow information:
Interest paid	2,529	1,823
Supplemental disclosure of non-cash investing and financing activities:
Issuance of commitment shares	0	862
Purchases of fixed assets included in accounts payable and accrued expenses	$ 0	$ 12

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Description of Business Locust Walk Acquisition Corp. ("LWAC”) was initially formed on October 2, 2020 as a Delaware corporation formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or other similar business transaction with one or more operating businesses. On May 26, 2021, LWAC entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Locust Walk Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of LWAC (“Merger Sub”), and eFFECTOR Therapeutics, Inc., a Delaware corporation (“Old eFFECTOR”). Pursuant to the terms of the Merger Agreement, a business combination between LWAC and Old eFFECTOR was effected through the merger of the Merger Sub with and into Old eFFECTOR, with Old eFFECTOR becoming the surviving company and a wholly-owned subsidiary of LWAC with the name of eFFECTOR Therapeutics Operations, Inc. On August 25, 2021, and in connection with the closing of the business combination (the "Business Combination"), LWAC was renamed eFFECTOR Therapeutics, Inc. ("eFFECTOR" or the "Company"). All outstanding preferred shares of Old eFFECTOR converted into common shares of Old eFFECTOR on a 1:1 basis, which were then converted, along with all outstanding common shares of Old eFFECTOR, into common shares of the surviving eFFECTOR company through application of an exchange ratio of approximately 0.09657 . The Company is a clinical-stage biopharmaceutical company focused on pioneering the development of a new class of oncology drugs the Company refers to as selective translation regulator inhibitors ("STRIs"). The Company’s principal operations are in the United States, with its headquarters in Solana Beach, California. The Company has devoted substantially all of its resources to raising capital, identifying potential product candidates, establishing its intellectual property portfolio, conducting preclinical studies and clinical trials, establishing arrangements with third parties for the manufacture of its product candidates and related raw materials, and providing general and administrative support for these operations. The Company has not generated revenues from its principal operations, other than from licensing and grant revenue, through December 31, 2023. Reverse Stock Split On January 9, 2024, the Company filed a Certificate of Amendment to the Company’s Amended and Restated Certificate of Incorporation, as amended to date, with the Secretary of State of the State of Delaware to effect a reverse stock split of the Company’s common stock, par value $ 0.0001 at a ratio of 1-for-25 (the “Reverse Stock Split”), as authorized at the Company’s 2023 annual meeting of stockholders held on June 22, 2023. The Company effected the Reverse Stock Split on January 12, 2024. No fractional shares were issued in connection with the Reverse Stock Split. Stockholders who otherwise were entitled to a fractional share of common stock were entitled to receive a proportional cash payment. The number of shares of common stock that the Company is authorized to issue was proportionally reduced from 1,000,000,000 shares to 40,000,000 shares and the par value of its common stock remains unchanged at $ 0.0001 per share. The Company has retroactively restated the share and per share amounts in the consolidated financial statements as of December 31, 2023 and 2022. Proportionate adjustments were made to the per share exercise price and number of shares of common stock issuable under all outstanding stock options and warrants. In addition, proportionate adjustments have been made to the number of shares of common stock reserved for the Company’s equity incentive compensation plans. The consolidated statements of stockholders’ equity (deficit) and balance sheets reflect the impact of the Reverse Stock Split by reclassifying from “common stock” to “additional paid-in capital” in an amount equal to the par value of the decreased shares resulting from the Reverse Stock Split. Basis of Presentation The Company’s consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). Liquidity The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or amounts and classification of liabilities that may result from the outcome of this uncertainty. Management is required to perform a two-step analysis over its ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern (step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (step 2). The Company has experienced net losses and negative cash flows from operating activities since its inception, aside from the years ended December 31, 2021 and December 31, 2020 when net income was realized as a result of a gain in fair value recognized associated with the earn-out liability and revenue in connection with the Research Collaboration and License Agreement with Pfizer, respectively. The Company has an accumulated deficit of $ 179.4 million at December 31, 2023. For the year ended December 31, 2023, the Company had a net loss of $ 35.8 million and used $ 29.6 million in cash for operations. At December 31, 2023, the Company had cash and cash equivalents and short-term investments of $ 18.4 million. The Company anticipates that its expenses will increase significantly in connection with its ongoing activities to support its research and development efforts, and it expects to incur substantial operating losses and negative cash flows from operations for the foreseeable future. Management has prepared cash flow forecasts which indicate that based on the Company’s expected operating losses and negative cash flows, there is substantial doubt about the Company’s ability to continue as a going concern within twelve months from the date that these financial statements for the year ended December 31, 2023 are issued. The principal payments due under the Oxford Loans (as defined below), and the related accrued final payment, have been classified as current liabilities as of December 31, 2023, due to the considerations discussed above and the assessment that the material adverse change clause under the Oxford Loans is not within the Company’s control. The Company has not been notified of an event of default by the lender as of the date of issuance of these financial statements. The Company’s ability to continue as a going concern is dependent upon its ability to receive additional capital. Management intends to raise additional capital through equity offerings or other capital sources, including potential additional collaborations, licenses and other similar arrangements. Additionally, the Company may receive additional milestone payments from the Research Collaboration and License Agreement with Pfizer (described in Note 11), through the issuance of common stock under the equity purchase agreement (the "Purchase Agreement") with Lincoln Park Capital Fund, LLC ("Lincoln Park") (described in Note 8) or through the issuance of common stock under the at-the-market offering program (described in Note 8) with Cantor Fitzgerald & Co ("Cantor"). However, the Company may not be able to secure additional financing in a timely manner or on favorable terms, if at all, and may not receive any milestone payments. Without additional capital, the Company may be forced to delay, scale back or eliminate some of its research and development activities, or other operations and potentially delay product development in an effort to provide sufficient funds to continue its operations, or may be required to pursue merger or acquisition strategies, all of which could adversely affect the holdings or the rights of its stockholders.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The Company’s consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of the Company’s consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimate in the Company’s consolidated financial statements relates to its clinical trial expense accruals. Management evaluates its estimates on an ongoing basis. Although these estimates are based on the Company’s historical experience, knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Cash, Cash Equivalen ts and Short-term Investments Cash and Cash Equivalents The Company considers all highly liquid investments with insignificant interest rate risk and an original maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist of money market funds and U.S. Treasury securities with an original maturity of less than three months at the date of purchase. Short-term Investments Short-term investments consist of U.S. Treasury securities, classified as available-for-sale securities and have maturities of greater than three months but less than one year. The Company has classified all of its available-for-sale securities as current assets on the balance sheets because these are considered highly liquid securities and are available for use in current operations. The Company carries these securities at fair value, and reports unrealized gains and losses as a separate component of accumulated other comprehensive income (loss). Amortization and accretion of any purchase premiums or discounts is included in interest income in the consolidated statements of operations and comprehensive loss. Fair Value of Financial Instruments The carrying amounts of all cash equivalents, prepaid expenses and other assets, accounts payable and accrued liabilities are reasonable estimates of their fair value because of the short-term nature of these items. Based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes the fair value of the term loans approximate their carrying value (see Note 6). Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash and cash equivalents and short-term investments. The Company maintains deposits in a federally insured major financial institution in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institution in which those deposits are held. The Company is subject to a number of risks similar to other biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of current or future preclinical studies or clinical trials, reliance on third parties or partners to conduct its clinical trials, the need to obtain regulatory and marketing approvals for its drug candidates or to rely on partners to do so, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of its drug candidates, the right to develop and commercialize drug candidates pursuant to the terms and conditions of the licenses granted to the Company, protection of proprietary technology, the ability to make milestone, royalty or other payments due under any license or collaboration agreements, and the need to secure and maintain adequate manufacturing arrangements with third parties. If the Company does not successfully commercialize or partner any of its drug candidates, it will be unable to generate product revenue or achieve profitability. Property and Equipment Property and equipment are recorded at cost and depreciated or amortized using the straight-line method over the estimated useful lives of the assets (generally three to five years , or the remaining term of the lease for leasehold improvements , whichever is shorter) and generally consist of laboratory equipment, computer and office equipment, furniture and fixtures, and leasehold improvements. Repairs and maintenance costs are charged to expense as incurred. Long-Lived Assets The Company regularly reviews the carrying value and estimated lives of all of its long-lived assets, including property and equipment to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. Should an impairment exist, the impairment loss would be measured based on the excess over the carrying amount of the asset’s fair value. The Company has no t recognized any impairment losses from inception through December 31, 2023. Leases At the commencement date of a lease, the Company recognizes lease liabilities which represent its obligation to make lease payments, and right-of-use assets ("ROU assets") which represent its right to use the underlying asset during the lease term. The lease liability is measured at the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at the lease commencement date. The ROU asset is measured at cost, which includes the initial measurement of the lease liability and initial direct costs incurred by the Company and excludes lease incentives. ROU assets are recorded in operating lease ROU assets and lease liabilities are recorded in operating lease liabilities, current and noncurrent in the balance sheets. Grant Revenue The Company had grant revenues in 2022 derived from a grant with the Defense Advanced Research Projects Agency (“DARPA”) through the University of California, San Francisco (“UCSF”). The Company recognized DARPA grant revenue as reimbursable grant costs are incurred up to pre-approved award limits within the budget period. The costs associated with these reimbursements are reflected as a component of research and development expense in the accompanying 2022 consolidated statements of operations and comprehensive loss. Billings in excess of receipts are included as a receivable recorded within prepaid expenses and other current assets on the consolidated balance sheets. Research and Development Costs Research and development expenses primarily consist of costs associated with the preclinical and clinical development of the Company’s product candidates. Research and development costs are expensed as incurred. Clinical Trial Accruals and Preclinical Studies The Company records expenses resulting from our obligations under contracts with vendors and consultants, CROs and clinical sites in connection with conducting clinical trials and preclinical studies. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company reflects clinical trial and preclinical study expenses in the financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the clinical trial or preclinical study as measured by the timing of various aspects of the clinical trial, preclinical study, or related activities. The Company determines accrual estimates based on the underlying contracts, correspondence with clinical and other key personnel and third-party service providers as to the progress of the clinical trials, preclinical studies, or other services being conducted, and amounts invoiced or paid to date. During the course of a clinical trial or preclinical study, the Company adjusts the rate of expense recognition if actual results differ from estimates. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain. Revenue Recognition The Company evaluates collaboration arrangements to determine whether units of account within the collaboration arrangement exhibit the characteristics of a vendor and customer relationship. For arrangements and units of account where a customer relationship exists, the Company applies the revenue recognition guidance. The Company recognizes revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies the performance obligations. At contract inception, the Company assesses the goods or services promised within each contract and assesses whether each promised good or service is distinct and determines those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition on a prospective basis. For research and development services performed under a collaboration agreement in which the performance obligation is satisfied over time, the Company measures the progress of the activities using an input method. The input methods used are based on the effort expended or costs incurred toward the satisfaction of the related performance obligation. The Company estimates the amount of effort expended, including the time the Company estimates it will take to complete the activities, or costs incurred 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 consideration allocated to the research and development services to determine the amount of revenue recognized each period. This approach requires estimates and the use of significant judgement. If the estimates or judgements change over the course of the collaboration, they may affect the timing and amount of revenue recognized in the current and future periods. Milestones At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company or the Company’s collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the Company’s estimate of the overall transaction price. Any such adjustments are allocated on a cumulative catch-up basis to satisfied and partially satisfied performance obligations, with the consideration allocated to an ongoing performance obligation being recognized over the period of performance. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, 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. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. As of December 31, 2023 and 2022, the Company maintained valuation allowances against its deferred tax assets as the Company concluded it had not met the “more likely than not” to be realized threshold. Changes in the valuation allowance when they are recognized in the provision for income taxes may result in a change in the estimated annual effective tax rate. The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability. Comprehen sive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company presents comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment. Stock-Based Compensation Expense Stock-based compensation expense represents the cost of the grant date fair value of employee stock option grants recognized over the requisite service period of the awards (usually the vesting period) on a straight- line basis. The Company estimates the fair value of stock option grants using the Black-Scholes option-pricing model. The Company accounts for stock options granted to non-employees using the fair value approach. The Black-Scholes option-pricing model requires the use of subjective assumptions, including the risk- free interest rate, the expected stock price volatility, the expected term of stock options, and the expected dividend yield. The Company has limited historical stock option activity and therefore estimates the expected term of stock options granted using the simplified method, which represents the average of the contractual term of the stock option and its weighted-average vesting period. The fair value of the underlying common stock used within the Black-Scholes option-pricing model is based on the closing price of common stock on the date of grant. Public and Private Placement Warrants Upon completion of the Business Combination, the Company assumed public and private placement warrants that were issued by LWAC in connection with their initial public offering in January 2021 whereby holders of the public and private placement warrants are entitled to acquire common stock of the Company. The Company has concluded that the public warrants are equity-classified. Since the settlement value of the private placement warrants is dependent, in part, on who holds the warrants at the time of settlement, they are not considered indexed to the Company's stock and are therefore recorded as liabilities. Warrants classified as liabilities are recorded at their estimated fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized in other income (expense), net in the accompanying consolidated statements of operations and comprehensive loss. The Company estimates the fair value of these warrants using the Black-Scholes option pricing model. Common Stock and Placement Agent Warrants In May 2023 and June 2023, the Company completed two separate registered direct offerings whereby common stock warrants and placement agent warrants were issued with the right to acquire common stock of the Company. In order to determine the appropriate accounting treatment for the warrants, the Company considered the indexation guidance under Accounting Standards Codification ("ASC") 815-40. The Company has concluded that the common stock warrants and placement agent warrants issued in the May 2023 and June 2023 registered direct offerings are equity classified as they are considered indexed to the Company's stock and do not contain any settlement provisions that would preclude equity classification. Earn-Out Shares In accordance with the Merger Agreement, 200,000 shares ("Earn-Out Shares") were contingently issuable to Old eFFECTOR stockholders and option holders upon the occurrence of the Triggering Event, defined within the Merger Agreement as the date on which the common stock price equals or exceeds $ 500.00 over at least 20 trading days out of a 30 consecutive trading day period during the two-year period following the close date of the Business Combination. The estimated fair value of the Earn-Out Shares was determined using a Monte Carlo simulation valuation model using a distribution of potential outcomes on a monthly basis over the earn-out period using the most reliable information available. The Company determined that the contingent obligation to issue Earn-Out Shares to existing Old eFFECTOR stockholders was not indexed to the Company's stock under ASC 815-40 and therefore equity treatment was precluded. The Triggering Event that would determine the issuance of the Earn-Out Shares included terms that were not solely indexed to our common stock, and as such liability classification was required. Equity-linked instruments classified as liabilities are recorded at their estimated fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized in other income (expense), net in the accompanying consolidated statements of operations and comprehensive loss. The Company has determined that the contingent obligation to issue Earn-Out Shares to existing Old eFFECTOR option holders falls within the scope of ASC 718, Share-based Compensation, because the option holders were required to continue providing service until the occurrence of the Triggering Event. The fair value of the option holder Earn-Out Shares was recorded as share-based compensation over the derived service period of the Monte Carlo simulation valuation model, recognized in research and development and general and administrative expense in the consolidated statements of operations and comprehensive loss. The Triggering Event did not occur during the two-year period following the close date of the Business Combination and the achievement period for the earn-out expired on August 25, 2023. As such, the Old eFFECTOR stockholders and option holders are no longer eligible to receive Earn-Out shares as of August 25, 2023. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board ("FASB") or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes, based on its preliminary assessment, that the impact of recently issued standards that are not yet effective will not have a material impact on their financial position or results of operations upon adoption. In November 2023, the Financial Accounting Standards Board (“FASB”) issued updated accounting guidance related to annual and interim segment disclosures. The updated accounting guidance, among other things, requires disclosure of certain significant segment expenses. We will adopt the updated accounting guidance in our Annual Report on Form 10-K for the year ended December 31, 2024. We do not expect impact from the adoption of the new accounting guidance will have material impact to our segment disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. The update requires a public business entity to disclose, on an annual basis, a tabular rate reconciliation using both percentages and currency amounts, broken out into specified categories with certain reconciling items further broken out by nature and jurisdiction to the extent those items exceed a specified threshold. In addition, all entities are required to disclose income taxes paid, net of refunds received disaggregated by federal, state/local, and foreign and by jurisdiction if the amount is at least 5% of total income tax payments, net of refunds received. Adoption of the ASU allows for either the prospective or retrospective application of the amendment and is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company has not yet completed its assessment of the impact of ASU 2023-09 on the Company’s Consolidated Financial Statements. We do not believe that any other recently issued, but not yet effective accounting pronouncements, if adopted, would have a material impact on our consolidated financial statements or disclosures. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Potentially dilutive securities as of December 31, 2023 and 2022 are as follows (in common stock equivalent shares, each as adjusted to reflect the Reverse Stock Split): For the Year Ended December 31, 2023 2022 Common stock warrants 768,592 — Placement agent warrants 53,799 — Public warrants 233,332 233,332 Private placement warrants 7,266 7,266 Earn-Out Shares — 200,000 Unvested sponsor shares 12,000 12,000 Stock options outstanding 480,875 349,495 Total 1,555,864 802,093

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e. supported by little or no market activity). The Company’s cash equivalents are classified using Level 1 inputs within the fair value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring ba sis. No transfers between levels have occurred during the periods presented. The Company estimates the fair value of its warrant liabilities at the time of issuance and subsequent remeasurement using the Black-Scholes option pricing model at each reporting date, if required, based on the following inputs: the risk-free interest rates; the expected dividend rates; the remaining contractual life of the warrants; the fair value of the underlying stock; and the expected volatility of the price of the underlying stock. The estimates are based, in part, on subjective assumptions and could differ materially in the future. Changes to these assumptions as well as the fair value of the Company’s stock on the reporting date can have a significant impact on the fair value of the warrant liability. The following table summarizes the Company’s assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy as of December 31, 2023 and December 31, 2022 (in thousands): Fair Value Measurements Using December 31, Quoted Prices Significant Significant 2023 Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 10,887 $ 10,887 $ — $ — U.S. Treasury securities 3,988 — 3,988 — Short-term investments: U.S. Treasury securities 3,495 — 3,495 — Total assets $ 18,370 $ 10,887 $ 7,483 $ — Liabilities Private placement warrant liability $ 40 $ — $ — $ 40 Total liabilities $ 40 $ — $ — $ 40 Fair Value Measurements Using December 31, Quoted Prices Significant Significant 2022 Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 8,708 $ 8,708 $ — $ — Short-term investments: U.S. Treasury securities 17,602 — $ 17,602 — Total assets $ 26,310 $ 8,708 $ 17,602 $ — Liabilities Private placement warrant liability $ 40 $ — $ — $ 40 Earn-out liability 6 — — 6 Total liabilities $ 46 $ — $ — $ 46 Cash Equivalents and Short-Term Investments Financial assets measured at fair value on a recurring basis consist of the Company’s cash equivalents and short-term investments. The Company obtains pricing information from its investment manager and generally determines the fair value of investment securities using standard observable inputs, including reported trades, broker/dealer quotes, and bids and/or offers. Investments are classified as Level 1 within the fair value hierarchy if their quoted prices are available in active markets for identical securities. Investments in money market funds of $ 10.9 million and $ 8.7 million as of December 31, 2023 and December 31, 2022, respectively, were classified as Level 1 instruments and were included in cash and cash equivalents. Investments in marketable securities are valued using Level 2 inputs. Level 2 securities are initially valued at the transaction price and subsequently valued and reported upon utilizing inputs other than quoted prices that are observable either directly or indirectly, such as quotes from third-party pricing vendors. Fair values determined by Level 2 inputs, which utilize data points that are observable such as quoted prices, interest rates and yield curves, require the exercise of judgment and use of estimates, that if changed, could significantly affect the Company’s financial position and results of operations. Accrued interest receivable related to short-term investments was $ 52,000 and $ 27,000 as of December 31, 2023 and December 31, 2022, respectively, and included as part of prepaid expenses and other current assets in the consolidated balance sheets. The following tables summarize the Company’s short-term investments accounted for as available-for-sale securities as of December 31, 2023 and December 31, 2022 (in thousands): December 31, 2023 Maturity Amortized Unrealized Unrealized Estimated (in years) Cost Gains Losses Fair Value U.S. Treasury securities 1 year or less $ 3,495 $ — $ — $ 3,495 $ 3,495 $ — $ — $ 3,495 December 31, 2022 Maturity Amortized Unrealized Unrealized Estimated (in years) Cost Gains Losses Fair Value U.S. Treasury securities 1 year or less $ 17,620 $ 1 $ ( 19 ) $ 17,602 $ 17,620 $ 1 $ ( 19 ) $ 17,602 Private Placement Warrant Liability In connection with the Business Combination, the Company assumed the public and private placement warrants described in Note 2. The private placement warrants are p recluded from equity treatment and are recorded as liabilities as they are not considered indexed to the Company's common stock. The private placement warrant liability is measured at fair value, using a combination of observable and unobservable inputs. The change in fair value of the private placement warrant liability is recorded in other income (expense) on the statement of operations and comprehensive loss. The following key assumptions were used in determining the fair value of the private placement warrant liability valued using the Black-Scholes option pricing model as of December 31, 2023 and December 31, 2022: December 31, December 31, Common stock price $ 11.69 $ 10.69 Expected volatility 125.0 % 125.0 % Risk-free interest rate 4.1 % 4.2 % Expected term (in years) 2.7 3.7 Expected dividend yield — — The following table presents activity for the private placement warrant liability measured at fair value using significant unobservable Level 3 inputs during the year ended December 31, 2023 (in thousands): Private Placement Warrant Liability Balance at December 31, 2022 40 Change in fair value — Balance at December 31, 2023 $ 40

Property and Equipment , net

Property and Equipment , net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment , net	4. Property and Equipment, ne t Property and equipment, net consists of the following (in thousands): December 31, December 31, Lab equipment $ 30 $ 30 Computer and office equipment 154 149 Furniture and fixtures 78 61 Leasehold improvements 188 188 Construction in process 14 29 464 457 Less accumulated depreciation and amortization ( 324 ) ( 216 ) $ 140 $ 241

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expense s Accrued expenses consist of the following (in thousands): December 31, December 31, Employee compensation $ 1,587 $ 1,385 Research and development 1,036 1,206 Professional and outside services 75 112 Interest 223 197 Other — 468 $ 2,921 $ 3,368

Term Loans

Term Loans	12 Months Ended
	Dec. 31, 2023
Notes and Loans Payable, by Type, Current and Noncurrent [Abstract]
Term Loans	6. Term Loans Oxford Term Loans In March 2021, Old eFFECTOR entered into a Loan and Security Agreement (“Oxford LSA”) with Oxford Finance LLC (“Oxford”), pursuant to which the Company may borrow up to $ 30.0 million, issuable in two separate tranches of $ 20.0 million (“Term A Loans”) and $ 10.0 million (“Term B Loans”), collectively referred to as the Oxford Loans. In March 2021, the Company borrowed $ 20.0 million of the Term A Loans. The Company is required to make a final payment equal to 5.5 % of the Term A Loans at maturity, which has been recorded as a debt discount for the Term A Loans and is being amortized over the term of the debt arrangements. In connection with the Oxford LSA, the Company issued warrants to purchase a total of 1,503 shares of Series C Preferred Stock at an exercise price of $ 133.25 per share. On February 22, 2022, the Company entered into an amendment to the Oxford LSA whereby the interest only period for the Term A Loans ended on March 1, 2024 . In connection with the amendment, the maturity of the Term A Loans was extended from March 18, 2026 to February 1, 2027. Additionally, Term B Loans would have become available to the Company after January 1, 2023 upon achievement of certain clinical development milestones, until the earlier of (i) June 30, 2023 , (ii) 45 days after the achievement of certain clinical development milestones, and (iii) the occurrence of an event of default. As the Company did not achieve the clinical development milestones by June 30, 2023, it no longer has access to the additional $ 10.0 million under the Term B Loans. The amendment was accounted for as a debt modification as the modified debt was not substantially different from the original debt and the cash flows were not significantly changed. The Oxford Loans carry a variable interest rate equal to the greater of (i) 7.7 % and (ii) the sum of the prime rate plus 4.45 %. The Company has the option to prepay all, but not less than all, of the borrowed amounts, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3.0 % of the outstanding principal balance of the applicable Oxford Loans if prepayment is made prior to the first anniversary of the effective date of the Oxford LSA, (ii) 2.0 % of the outstanding principal balance of the applicable Oxford Loans if prepayment is made after the first anniversary of the effective date of the Oxford LSA but before the second anniversary, and (iii) 1.0 % of the outstanding principal balance of the applicable Oxford Loans if prepayment is made after the second anniversary of the effective date of the Oxford LSA but before the third anniversary. No prepayment fee will apply for a prepayment made after the third anniversary of the effective date of the Oxford LSA and prior to the maturity date. The Company’s obligations under the Oxford LSA are secured by a first priority security interest in substantially all of its current and future assets, other than its owned intellectual property. The Company is also obligated to comply with various other customary covenants, including restrictions on its ability to encumber intellectual property assets without consent. The Company recorded a debt discount of $ 1.6 million for the estimated fair value of warrant s, debt issuance costs, and final payment to be made, which is being amortized to interest expense over the term of the loan using the effective-interest method. As of December 31, 2023 , the Company had $ 20.0 million of outstanding principal under the Term A Loans of which $ 19.4 million is reflected on the balance sheet net of debt discounts. Interest expense, including amortization of debt discount related to the Oxford Term A Loans, totaled $ 2.9 million for the year ended December 31, 2023. The Company is in compliance with all covenants under the Oxford LSA as of December 31, 2023. The Term A Loans include customary events of default, including instances of a material adverse change in our operations, that may require prepayment of the outstanding Term A Loans. The principal payments due under the Oxford Loans, and the related accrued final payment, have been classified as current liabilities as of December 31, 2023, due to the considerations discussed in the Liquidity section of Note 1. The Company has not been notified of an event of default by the lender as of the date of issuance of these financial statements. Based on the outstanding principal amounts for the Company’s Term A Loans, the following table sets forth by year the Company’s required future principal payments as of December 31, 2023 (in thousands): As of December 31, 2023 2024 $ 5,555 2025 6,667 2026 6,667 2027 1,111 Required future principal payments $ 20,000 Unamortized debt discount ( 615 ) Current term loans, net as of December 31, 2023 $ 19,385

Warrants

Warrants	12 Months Ended
	Dec. 31, 2023
Warrants and Rights Note Disclosure [Abstract]
Warrants	7. Warrants Assumed Public Warrants and Private Placement Warrants Following the consummation of the Business Combination, holders of the public warrants and private placement warrants are entitled to acquire common stock of the Company. The warrants became exercisable on January 12, 2022, which is 12 months from the closing of the LWAC's initial public offering. Each warrant entitles the registered holder to purchase one share of common stock at an exercise price of $ 287.50 per share. The public warrants and private placement warrants will expire on August 25, 2026, which is five years after the completion of the Business Combination. Once the public warrants and private placement warrants became exercisable, the Company has the right to redeem the outstanding warrants in whole and not in part at a price of $ 0.25 per warrant upon a minimum of 30 days’ prior written notice of redemption, if and only if the last sale price of the common stock equals or exceeds $ 450.00 per share for any 20 trading days within a 30 -trading day period ending on the third trading day prior to the date on which the Company sends the notice of redemption to the warrant holders. The private placement warrants are identical to the public warrants except that, so long as they are held by the sponsor or its permitted transferees: (i) they will not be redeemable by the Company; (ii) they may be exercised by the holders on a cashless basis; and (iii) they are subject to registration rights. Private placement warrants are liability-classified (See Note 3) and the public warrants are equity-classified. The following table summarizes the number of outstanding public warrants and private placement warrants and the corresponding exercise price as of December 31, 2023 and December 31, 2022: December 31, December 31, Exercise Price Expiration Date Public warrants 233,332 233,332 $ 287.50 August 24, 2026 Private placement warrants 7,266 7,266 $ 287.50 August 24, 2026 Warrants - Registered Direct Offerings In May 2023, the Company completed a registered direct offering (“May 2023 Registered Direct Offering”) which included the issuance of 270,015 shares of common stock in the form of pre-funded warrants with a purchase price of $ 16.35 per share and an exercise price of $ 0.025 (the “May 2023 Pre-Funded Warrants”). The May 2023 Pre-Funded Warrants were immediately exercised. Additionally, in a concurrent private placement, the Company issued warrants to purchase up to 458,015 shares of common stock (the “May 2023 Common Stock Warrants”) with an exercise price of $ 13.25 per share. The May 2023 Common Stock Warrants will expire on November 30, 2028 , which is five and one-half years from the issuance date. Further, the Company issued warrants to designees of the placement agent to purchase up to 32,060 shares of common stock ("May 2023 Placement Agent Warrants") with an exercise price of $ 20.47 per share. The May 2023 Placement Agent Warrants will expire on May 26, 2028 , which is five years following the commencement of sales in the May 2023 Registered Direct Offering. See Note 8 for additional detail surrounding the May 2023 Registered Direct Offering. In June 2023, the Company completed a registered direct offering (“June 2023 Registered Direct Offering”) which included the issuance of 72,578 shares of common stock in the form of pre-funded warrants with a purchase price of $ 28.10 per share and an exercise price of $ 0.025 (the “June 2023 Pre-Funded Warrants”). The June 2023 Pre-Funded Warrants were immediately exercised. Additionally, in a concurrent private placement, the Company issued warrants to purchase up to 310,577 shares of common stock (the “June 2023 Common Stock Warrants”) with an exercise price of $ 25.00 per share. The June 2023 Common Stock Warrants will expire on December 8, 2028 , which is five and one-half years from the issuance date. Further, the Company issued warrants to designees of the placement agent to purchase up to 21,739 shares of common stock ("June 2023 Placement Agent Warrants") with an exercise price of $ 35.1575 per share. The June 2023 Placement Agent Warrants will expire on June 6, 2028 , which is five years following the commencement of sales in the June 2023 Registered Direct Offering. See Note 8 for additional detail surrounding the June 2023 Registered Direct Offering. The common stock warrants and placement agent warrants are equity-classified. The following table summarizes the number of outstanding common stock warrants and placement agent warrants and the corresponding exercise price as of December 31, 2023 and December 31, 2022: December 31, December 31, Exercise Price Expiration Date May 2023 Common Stock Warrants 458,015 — $ 13.25 November 30, 2028 May 2023 Placement Agent Warrants 32,060 — $ 20.47 May 26, 2028 June 2023 Common Stock Warrants 310,577 — $ 25.00 December 8, 2028 June 2023 Placement Agent Warrants 21,739 — $ 35.1575 June 6, 2028

Preferred Stock and Stockholder

Preferred Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Preferred Stock and Stockholders' Deficit	8. Preferred Stock and Stockholders’ Equity Purchase Agreement On January 24, 2022, the Company entered into the Purchase Agreement and a registration rights agreement with Lincoln Park which provides for the sale to Lincoln Park up to $ 50.0 million of shares (the “Purchase Shares”) of the Company's common stock over the thirty-six ( 36 ) month term of the Purchase Agreement. In connection with the Purchase Agreement, Lincoln Park made an initial purchase of $ 3.0 million of shares of common stock, which equated to 22,304 shares of common stock, and the Company issued 5,717 shares of common stock to Lincoln Park as a commitment fee in connection with entering into the Purchase Agreement. The Company recognized $ 0.8 million of other expense relating to the commitment fee share issuance. As of December 31, 2023, a total of 1,200 shares of common stock have been sold in addition to the upfront amount. There were no purchases under the Purchase Agreement during the year ended December 31, 2023. Under the Purchase Agreement, the Company has sole discretion, subject to certain conditions, on any business day selected by the Company to require Lincoln Park to purchase up to 1,200 shares of common stock (the “Fully Adjusted Regular Purchase Share Limit”) at the Purchase Price (as defined below) per purchase notice (each such purchase, a “Regular Purchase”). The Fully Adjusted Regular Purchase Share Limit may be increased as follows: to up to 2,000 shares if the closing price is not below $125.00, and up to 3,000 shares if the closing price is not below $250.00 . Lincoln Park’s committed obligation under each Regular Purchase is capped at $ 500,000 , unless the Parties agree otherwise. The purchase price for Regular Purchases (the “Purchase Price”) shall be equal to the lesser of: (i) the lowest sale price of the common shares during the Purchase Date (as defined in the Purchase Agreement), or (ii) the average of the three (3) lowest closing sale prices of the common shares during the ten (10) business days prior to the Purchase Date. In addition to Regular Purchases and subject to certain conditions and limitations, the Company in its sole discretion may require Lincoln Park on each Purchase Date to purchase on the following business day up to the lesser of (i) three (3) times the number of shares purchased pursuant to such Regular Purchase or (ii) 25 % of the trading volume on the Accelerated Purchase Date (as defined in the Purchase Agreement) (the “Accelerated Purchase”) (unless the Parties agree otherwise) at a purchase price equal to the lesser of 97 % of (i) the closing sale price on the Accelerated Purchase Date, or (ii) the Accelerated Purchase Date’s volume weighted average price (the “Accelerated Purchase Price”). The Company has the sole right to set a minimum price threshold for each Accelerated Purchase in the notice provided with respect to such Accelerated Purchase and under certain circumstances and in accordance with the Purchase Agreement the Company may direct multiple Accelerated Purchases in a day. The aggregate number of shares that the Company can sell to Lincoln Park under the Purchase Agreement may not exceed 325,357 shares of the Common Shares (which is equal to approximately 19.99 % of the shares of the Common Shares outstanding immediately prior to the execution of the Purchase Agreement) (the “Exchange Cap”), unless (i) shareholder approval is obtained to issue Purchase Shares above the Exchange Cap, in which the Exchange Cap will no longer apply, or (ii) the average price of all applicable sales of Common Shares to Lincoln Park under the Purchase Agreement equals or exceeds $ 160.50 per share; provided that at no time may Lincoln Park (together with its affiliates) beneficially own more than 4.99 % of the Company’s issued and outstanding Common Shares. The Purchase Agreement contains customary representations, warranties, covenants, closing conditions, indemnification and termination provisions. The Purchase Agreement may be terminated by the Company at any time, at its sole discretion, without any cost or penalty, by giving one business day notice to Lincoln Park. Further, Lincoln Park has covenanted not to engage in any direct or indirect short selling or hedging of the Common Shares. There are no limitations on the use of proceeds, financial or business covenants, restrictions on future financings (other than restrictions on the Company’s ability to enter into a similar type of agreement or Equity Line of Credit during the Term, excluding an At-The-Market transaction with a registered broker-dealer), rights of first refusal, participation rights, penalties or liquidated damages in the Purchase Agreement. At-the-Market Offering Program In September 2022, the Company entered into a Controlled Equity Offering Sales Agreement (the "Sales Agreement") with Cantor, under which the Company may, from time to time, sell shares of the Company’s common stock having an aggregate offering price of up to $50 .0 million in “at the market” offerings (the "ATM Offering Program") through Cantor. Sales of the shares of common stock will be made at prevailing market prices at the time of sale, or as otherwise agreed with Cantor. Cantor will receive a commission from the Company of up to 3.0 % of the gross proceeds of any shares of common stock sold under the Sales Agreement. In August 2023, the Company amended and supplemented its prospectus, dated September 9, 2022 (the “Prospectus”), relating to the offer and sale of shares of its common stock pursuant to the Sales Agreement (the “Prospectus Supplement”) as the Company was no longer subject to General Instruction I.B.6. of Form S-3, which limited the amounts that the Company could sell under the registration statement of which the Prospectus and Prospectus Supplement are a part. In connection with filing this Annual Report on Form 10-K, we will amend and supplement the Prospectus to reduce the amount of shares which can be sold pursuant to the Sales Agreement to be no more than one-third our public float, as calculated on the day of filing. During the year ended December 31, 2023, the Company sold an aggregate of 537,200 shares of common stock at a weighted-average price of $ 13.48 per share for gross proceeds of approximately $ 7.2 million under the ATM Offering Program. Offering costs, including commissions, of approximately $ 0.4 million were recorded as an offset to gross proceeds within additional paid-in capital. During the year ended December 31, 2022, the Company sold an aggregate of 19,157 shares of common stock at a weighted-average price of $ 15.03 per share for gross proceeds of approximately $ 0.3 million under the ATM Offering Program. Offering costs, including commissions, of approximately $ 0.2 million were recorded as an offset to gross proceeds within additional paid-in capital. Registered Direct Offerings The May 2023 Registered Direct Offering included the issuance and sale of an aggregate of 188,000 shares of the Company’s common stock at a purchase price of $ 16.375 per share in a registered direct offering priced at-the-market under Nasdaq rules. In addition, the offering included the issuance of the May 2023 Pre-Funded Warrants, which were immediately exercised, and the May 2023 Common Stock Warrants. The Company received gross proceeds from the May 2023 Registered Direct Offering of $ 7.5 million with net proceeds of approximately $ 6.7 million after deducting $ 0.8 million in commissions and other transaction costs. In connection with the May 2023 Registered Direct Offering, the Company paid H.C. Wainwright & Co., LLC, as exclusive placement agent, an aggregate cash fee equal to 7.0 % of the gross proceeds received by the Company from the offering and a management fee equal to 1.0 % of the gross proceeds received by the Company from the offering. The Company also paid the placement agent $ 75,000 for non-accountable expenses and $ 15,950 for clearing fees. Additionally, the Company issued designees of the placement agent the May 2023 Placement Agent Warrants, equal to 7.0 % of the aggregate number of shares of common stock and pre-funded warrants placed in the offering. The June 2023 Registered Direct Offering included the issuance and sale of an aggregate of 238,000 shares of the Company’s common stock at a purchase price of $ 28.125 per share in a registered direct offering priced at-the-market under Nasdaq rules. In addition, the offering included the issuance of the June 2023 Pre-Funded Warrants, which were immediately exercised, and the June 2023 Common Stock Warrants. The Company received gross proceeds from the June 2023 Registered Direct Offering of $ 8.7 million with net proceeds of approximately $ 7.8 million after deducting $ 0.9 million in commissions and other transaction costs. In connection with the June 2023 Registered Direct Offering, the Company paid H.C. Wainwright & Co., LLC, as exclusive placement agent, an aggregate cash fee equal to 7.0 % of the gross proceeds received by the Company from the offering and a management fee equal to 1.0 % of the gross proceeds received by the Company from the offering. The Company also paid the placement agent $ 50,000 for non-accountable expenses and $ 15,950 for clearing fees. Additionally, the Company issued designees of the placement agent the June 2023 Placement Agent Warrants, equal to 7.0 % of the aggregate number of shares of common stock and pre-funded warrants placed in the offering. Preferred Stock Upon closing of the Business Combination transaction, pursuant to the terms of the Amended and Restated Certificate of Incorporation, 100,000,000 shares of preferred stock with a par value of $ 0.0001 per share were authorized. eFFECTOR's Board of Directors (the "Board of Directors") has the authority, without further action by the stockholders to issue such shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, and to fix the dividend, voting, and other rights, preferences and privileges of the shares. There were no issued and outstanding shares of preferred stock immediately after the closing of the Business Combination and no preferred stock has been issued as of December 31, 2023. Sponsor Shares In connection with the closing of the Business Combination, the LWAC sponsor received 162,250 shares of eFFECTOR common stock, of which 12,000 shares were subject to vesting if, on or prior to August 25, 2024, the price of shares of common stock equals or exceeds $ 375.00 per share for a period of at least 20 trading days out of 30 consecutive trading days ending on the trading day immediately prior to the date of determination (the "Sponsor Shares"). The 12,000 Sponsor Shares subject to vesting meet the criteria for equity classification, but are not considered outstanding from an accounting perspective. These shares are considered issued but not outstanding as of December 31, 2023 and December 31, 2022, and have been excluded from outstanding shares in the calculation of loss per share for the years ended December 31, 2023 and 2022. Employee Stock Purchase Plan The ESPP provides for six-month offering periods, and at the end of each offering period, employees are able to purchase shares at 85 % of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. An aggregate of 35,200 shares were initially reserved and available for issuance under the ESPP. The ESPP provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2022, by 1.0 % of the outstanding number of shares of common stock on the immediately preceding December 31, or such lesser amount as determined by our Board of Directors; provided that the total number of shares of common stock that become available for issuance under the ESPP will never exceed 600,000 . If our capital structure changes because of a stock dividend, stock split or similar event, the number of shares that can be issued under the ESPP will be appropriately adjusted. As of December 31, 2023, 59,144 shares were reserved for future issuance under the ESPP. During the years ended December 31, 2023 and 2022, 5,694 and 3,433 shares of common stock were issued under the ESPP, respectively. 2013 Equity Incentive Plan Prior to the Business Combination, Old eFFECTOR maintained its 2013 Equity Incentive Plan (the “2013 Plan”), under which Old eFFECTOR granted incentive stock options, restricted stock awards, and other stock-based awards to employees, directors, and non-employee consultants. Upon completion of the Business Combination, the Company ceased granting awards under the 2013 Plan and, as described below, all awards under the 2013 Plan were converted into awards under the 2021 Plan with the same terms and conditions. As of August 25, 2021, prior to the Business Combination transaction, 156,781 Old eFFECTOR options remained outstanding under the 2013 Plan . In connection with the completion of the Business Combination and the adoption of the 2021 Plan, no further awards will be granted under the 2013 Plan. As of December 31, 2023, there were 130,694 options outstanding under the 2013 Plan. 2021 Equity Incentive Plan In connection with the consummation of the Business Combination on August 25, 2021, the Board of Directors approved the adoption of the 2021 Equity Incentive Plan (the “2021 Plan”). As of Decem ber 31, 2023, 446,630 shares of common stock are authorized for issuance pursuant to awards under the 2021 Plan, inclusive of any shares of common stock subject to stock options, restricted stock awards or other awards that were assumed in the Business Combination. As of December 31, 2023, 375,506 options to purchase common shares have been awarded and 96,449 shares remain avail able for issuance under the 2021 Plan. The 2021 Plan permits the granting of incentive stock options, restricted stock awards, other stock-based award or other cash-based awards to employees, directors, and non-employee consultants. Options granted under the 2021 Plan are exercisable at various dates as determined upon grant and will expire no more than ten years from their date of grant, or in the case of certain non-statutory options, ten years from the date of grant. The exercise price of each option shall be determined by the Board of Directors based on the fair market value of the Company’s stock on the date of the option grant, defined as the closing sales price of the Company's common stock. In the case of incentive stock options, the exercise price shall not be less than 100 % of the fair market value of the Company’s common stock at the time the option is granted. For holders of more than 10 % of the Company’s total combined voting power of all classes of stock, incentive stock options may not be granted at less than 110 % of the fair market value of the Company’s stock at the date of grant and for a term not to exceed five years . A summary of the Company’s stock option activity under the plans is as follows (in thousands, except share and per share amounts and years): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2022 349,495 $ 68.23 7.4 $ — Granted 151,589 13.01 9.1 Exercised ( 3,590 ) 13.00 — Cancelled or forfeited ( 16,619 ) 55.70 6.6 Outstanding at December 31, 2023 480,875 $ 51.67 7.3 $ — Vested and exercisable at December 31, 2023 292,803 $ 57.64 6.3 $ — For the year ended December 31, 2023 the total fair value of vested options was $ 5.0 million. The weighted-average grant date fair value of employee and non-employee option grants during the year ended December 31, 2023 was $ 9.39 per share and $ 9.56 per share, respectively. The intrinsic value of options exercised during the years ended December 31, 2023 and 2022 was zero . Stock-Based Compensation Expense The Company recognized stock-based compensation expense specifically related to stock options of $ 4.6 million and $ 5.0 million for the years ended December 31, 2023 and 2022, respectively. The assumptions used in t he Black-Scholes option pricing model to determine the fair value of the stock option grants were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 3.6 % - 4.4 % 1.7 % - 4.1 % Expected volatility 84 % - 85 % 82 % - 86 % Expected term (in years) 5.3 - 6.1 5.2 - 6.1 Expected dividend yield 0 % 0 % Risk-free interest rate. The risk-free rate assumption is based on the U.S. Treasury instruments, the terms of which were consistent with the expected term of the Company’s stock options. Expected volatility. Due to the Company’s limited operating history and lack of company-specific historical or implied volatility, the expected volatility assumption was determined by examining the historical volatilities of a group of industry peers whose share prices are publicly available. Expected term. The expected term of stock options represents the weighted-average period the stock options are expected to be outstanding. The Company uses the simplified method for estimating the expected term as provided by the SEC. The simplified method calculates the expected term as the weighted average of the time-to-vesting and the contractual life of the options. Expected dividend yield. The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has not paid and does not intend to pay dividends. Forfeitures . The Company reduces stock-based compensation expense for actual forfeitures during the period in which they occur. As of December 31, 2023, the unrecognized compensation cost related to out standing employee options was $ 4.6 million and is expected to be recognized as expense over approximately 2.2 years. Unrecognized compensation cost related to outstanding nonemployee options was $ 0.9 million as of December 31, 2023 , and is expected to be recognized as expense over approximately 0.7 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance consists of the following as of December 31, 2023: December 31, Stock options issued and outstanding 480,875 Public warrants issued and outstanding 233,332 Private placement warrants issued and outstanding 7,266 Common stock warrants issued and outstanding 768,592 Placement agent warrants issued and outstanding 53,799 Unvested sponsor shares 12,000 Authorized for future stock awards or option grants 96,449 Authorized for future issuances under the ESPP 59,144 Total 1,711,457

Earn-out Shares

Earn-out Shares	12 Months Ended
	Dec. 31, 2023
Earn out Share [Abstract]
Earn-out Shares	9. Earn-Out Shares In accordance with the Merger Agreement, 200,000 Earn-Out Shares were contingently issuable to Old eFFECTOR stockholders and option holders upon the occurrence of the Triggering Event, defined within the Merger Agreement as the date on which the common stock price equals or exceeds $ 500.00 over at least 20 trading days out of 30 consecutive trading day period for the two-year period following the close date of the Business Combination. The Triggering Event did not occur during the two-year period following the close date of the Business Combination and therefore the achievement period for the earn-out expired on August 25, 2023. As such, the Old eFFECTOR stockholders and option holders are no longer eligible to receive Earn-Out shares as of August 25, 2023 and the value of the earn-out liability is zero as of December 31, 2023. The resulting reduction in value was recorded as a gain on change in fair value of the earn-out liability and included within the consolidated statements of operations and comprehensive loss for the year ended December 31, 2023. As of December 31, 2022, the stockholders and option holders were eligible to receive approximately 182,422 and 17,512 Earn-Out Shares, respectively. The fair value per share of the Earn-Out Shares was less than $ 0.01 as of December 31, 2022. The fair value was determined using a Monte Carlo simulation valuation model using a distribution of potential outcomes on a monthly basis over the earn-out period using the most reliable information available. Assumptions used in the valuation were as follows: December 31, Stock price $ 10.69 Expected volatility 115.0 % Risk-free interest rate 4.8 % Forecast period (in years) 0.6 Cost of equity 20.0 % Old eFFECTOR Stockholders The Company determined that the contingent obligation to issue Earn-Out Shares to existing Old eFFECTOR stockholders was not indexed to the Company's stock under ASC 815-40 and therefore equity treatment was precluded. The Triggering Event that would determine the issuance of the Earn-Out Shares includes terms that are not solely indexed to the common stock of the Company, and as such liability classification was required. The Company estimated the fair value of the shareholder Earn-Out Shares at date of issuance and revalued the liability each reporting period with the changes in fair value being recorded to the consolidated statements of operations and comprehensive loss. In accordance with the Merger Agreement, Earn-Out Shares attributable to Old eFFECTOR option holders who discontinue providing service before the occurrence of the Triggering Event are reallocated to the remaining eligible stockholders and option holders. As the two-year period following the close date of the Business Combination expired on August 25, 2023, the earn-out liability of approximately $ 6,000 was reduced to zero during the year ended December 31, 2023 and a gain on change in fair value was recognized on the consolidated statement of operations and comprehensive loss. For the year ended December 31, 2022, there was a decrease in the earn-out liability of $ 12.1 million which was recorded as a gain on change in fair value within the consolidated statement of operations and comprehensive loss. The contingent obligation, prior to the earn-out expiration, to issue Earn-Out Shares to existing Old eFFECTOR option holders falls within the scope of ASC 718, Share-based Compensation, because the option holders were required to continue providing service until the occurrence of the Triggering Event. The fair value of the option holder Earn-Out Shares at the consummation date of the Business Combination was approximately $ 7.9 million, which was recorded as share-based compensation over the derived service period of 0.36 years following the consummation of the Business Combination. For the year ended December 31, 2022 there was approximately $ 0.3 million recorded in share-based compensation related to the Earn-Out Shares, and the derived service period was completed as of March 31, 2022, with no additional share-based compensation expense to be recorded.

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2023
License Agreement Disclosure [Abstract]
License Agreement	10. License Agreements In May 2013, the Company entered into an agreement with the Regents of the University of California (“UCSF”) which provides the Company with an exclusive license to UCSF’s patent rights in certain inventions (the “UCSF Translational Profiling Patent Rights”) relating to translational profiling laboratory techniques initially developed at UCSF. Under the agreement, the Company is permitted to research, develop, make and sell products that it discovers and develops utilizing the UCSF Translational Profiling Patent Rights, which the Company refers to as licensed products, and use certain licensed processes utilizing the UCSF Translational Profiling Patent Rights and to sublicense such licensed products and processes. In July 2021, the Company entered into an amendment to the license agreement to confirm the impact of the Business Combination on the license agreement, including clarifying that in connection with the closing of the Business Combination, the Company would pay UCSF a one-time cash payment of approximately $ 1.0 million. The $ 1.0 million payment was made to UCSF in August 2021 in connection with the close of the Business Combination. The Company is also required to make cash milestone payments to UCSF upon the completion of certain clinical and regulatory milestones for the licensed products. No milestone events occurred during the years ended December 31, 2023 and December 31, 2022. The aggregate remaining potential milestone payments are approximately $ 375,000 . The Company paid an annual minimum royalty of $ 15,000 to UCSF during each of the years ended December 31, 2023 and 2022. All license related fees were recorded as research and development expense.

Research Collaboration and Lice

Research Collaboration and License Agreement	12 Months Ended
	Dec. 31, 2023
Research and Development [Abstract]
Research Collaboration and License Agreement	11. Research Collaboration and License Agreement In December 2019, the Company entered into a Research Collaboration and License Agreement (the “Pfizer Agreement”) with Pfizer to research and develop small molecules that target eIF4E. Under the Pfizer Agreement, the Company was responsible for initial research in collaboration with Pfizer, and Pfizer is responsible for all further development of the program, including submission of an investigational new drug application and conducting all clinical development and commercialization activities. Pfizer is obligated to use commercially reasonable efforts to develop and seek regulatory approval for a licensed product, and commercialize a licensed product where Pfizer has received regulatory approval, in the United States and certain other countries. In the event the Company exercises its co-funding and co-promotion option, a joint steering committee will oversee the development plan and budget of the co-developed product, and the Company will have the responsibility to conduct a portion of product marketing presentations to healthcare providers. Pursuant to the Pfizer Agreement, the Company received an upfront, one-time, non-refundable, non-creditable payment of $ 15 million from Pfizer. Pfizer was obligated to reimburse the Company for costs incurred for research performed, up to a specified cap in the low double-digit millions. Upon the achievement of specified early development and regulatory milestones, Pfizer will be obligated to pay the Company up to $ 80 million in the aggregate. For other non-early stage development milestones Pfizer’s payment obligations to the Company depends upon whether the Company has exercised its co-funding and co-promotion option: 1) if it does not exercise the option, non-early stage development payments may total up to $ 165 million in aggregate, and 2) if it does exercise the option, non-early stage development payments may total up to $ 70 million in aggregate. Upon the achievement of specified sales milestones, Pfizer is also obligated to make tiered milestone payments of up to $ 235 million in aggregate. On a product-by-product basis, Pfizer will also be required to pay the Company high single-digit percentage royalties on annual net sales of each licensed product. If the Company exercises its co-promotion and co-funding option, royalty payments will exclude sales in the United States and the Company will share with Pfizer profits from sale of the relevant licensed product in the United States. The initial transaction price of $ 27.0 million was allocated to the two performance obligations on a relative standalone value basis, with $ 25.6 million allocated to the license and $ 1.4 million allocated to the research activities, which were completed in 2020. The value attributable to the license was recognized upon delivery of the license to Pfizer and the value attributable to the research activities was recognized pro-rata based on the actual costs incurred by the Company compared to the total estimated costs of the research activities from the time of execution to the end of the research program. There was no revenue recorded in connection with this agreement for the years ended December 31, 2023 and 2022 because all development and sales milestones (variable consideration) were fully constrained.

DARPA Grant Revenue

DARPA Grant Revenue	12 Months Ended
	Dec. 31, 2023
DARPA Grant Revenue Disclosure [Abstract]
DARPA Grant Revenue	12. DARPA Grant Revenue In April 2021, the Company entered into a Research Subaward Agreement with UCSF (the "Subaward Agreement"), whereby up to $ 5.0 million in allowable costs were reimbursable for clinical and manufacturing activities related to zotatifin for the treatment of COVID-19. Under the terms of the Subaward Agreement, the Company was obligated to provide financial and technical reports to UCSF on a periodic basis. The Subaward Agreement can be terminated by either party upon written notice and also in the event that DARPA suspends or terminates its cooperative agreement with UCSF. The initial award period for the Subaward Agreement ended in December 2021, and in April 2022 the Company received an extension of the award period to December 2022, with the same maximum $ 5.0 million reimbursement amount. The Company did no t recognize any revenue under the Subaward Agreement in the year ended December 31, 2023. The Company recognized $ 3.6 million o f revenue under the Subaward Agreement in the year ended December 31, 2022. As of December 31, 2022, the Company exhausted the full $ 5.0 million of allowable reimbursable costs under the Subaward Agreement.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Leases In September 2021, the Company entered a non-cancelable three-year lease for certain office space in Solana Beach, California, with an option to renew for a n additional three-year term. In January 2024, the Company executed a three-year extension to the lease with a new expiration date of October 31, 2027. The initial term of the lease started on November 1, 2021, and is serving as the Company's headquarters. Rent expense under this lease was $ 0.1 million for each of the years ended December 31, 2023 and 2022. During each of the years ended December 31, 2023 and 2022, the Company paid $ 0.1 million in lease payments. All lease payments were included in operating activities in the statements of cash flows. The following table summarizes supplemental balance sheet information related to leases as of December 31, 2023 and December 31, 2022 (in thousands): December 31, December 31, Assets: Operating lease right-of-use assets $ 53 $ 111 Total right-of-use assets 53 111 Liabilities Operating lease liabilities, current 60 60 Operating lease liabilities, non-current — 60 Total operating lease liabilities $ 60 $ 120 As of December 31, 2023, the future minimum annual lease payments under the existing operating leases were as follows (in thousands, except for weighted-average remaining lease term and weighted-average discount rate): 2024 62 Total remaining lease payments 62 Less: imputed interest ( 2 ) Total operating lease liabilities 60 Less: current portion ( 60 ) Long-term operating lease liabilities $ - Weighted-average remaining lease term ( in years ) 0.83 Weighted-average discount rate 8 %

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefits	14. Employee Benefits The Company has a defined contribution 401(k) plan available to eligible employees. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation, limited to the maximum amount allowable under federal tax regulations. The Company, at its d iscretion, may make certain contributions to the 401(k) plan. Through December 31, 2023, the Company made no matching contributions.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	15. Income Taxes There was no income tax expense recorded by the Company for the years ended December 31, 2023 and 2022. Significant components of the Company’s net deferred tax assets are summarized as follows (in thousands): December 31, December 31, Deferred tax assets: Net operating loss carryforwards $ 46,365 $ 42,243 Intangibles 174 189 Research and development capitalization 6,525 3,839 Accrued compensation 2,070 2,282 Credits 9,395 8,013 Fixed assets 21 10 Other, net 99 88 Right-of-use liability 13 25 Deferred tax assets 64,662 56,689 Deferred tax liabilities: Right-of-use asset ( 11 ) ( 23 ) Deferred tax liabilities ( 11 ) ( 23 ) Net deferred tax assets 64,651 56,666 Valuation allowance ( 64,651 ) ( 56,666 ) Net deferred tax assets $ — $ — A reconciliation of the income tax computed at the federal statutory tax rate to the expense (benefit) for income taxes for the years ended December 31, 2023 and 2022 is as follows (in thousands ): December 31, December 31, Tax at statutory rate $ ( 7,520 ) $ ( 4,760 ) State income taxes, net of federal benefits — ( 2,076 ) Change in valuation allowance 7,990 7,726 Uncertain tax positions 793 586 Gain on change in fair value of earn-out liability ( 1 ) ( 2,546 ) Permanent differences and other 974 281 Transaction costs 6 244 Capitalized R&D — 3,381 LWAC net operating loss ( 259 ) ( 1,370 ) Credits ( 1,983 ) ( 1,466 ) Income tax expense $ — $ — Management assesses all available evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. The Company has experienced net losses since inception (aside from the years ended December 31, 2021 and December 31, 2020 when net income was realized as a result of a gain in fair value recognized associated with the earn-out liability and non-recurring revenue in connection with the Research Collaboration and License Agreement with Pfizer, respectively), and the revenue and income potential of the Company’s business and market are unproven. Due to the Company’s continuing research and development activities, the Company expects to continue to incur net losses into the foreseeable future. As such, the Company cannot conclude that it is more likely than not that its deferred tax assets will be realized. A valuation allowance of $ 64.7 million and $ 56.7 million at December 31, 2023 and 2022, respectively, has been established to offset the deferred tax assets, as realization of such assets is uncertain. Utilization of net operating loss (“NOL”) and research and development (“R&D”) credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the “Code”), as well as similar state and foreign provisions. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. Since the Company’s formation, the Company has raised capital through the issuance of capital stock on several occasions, which on its own or combined with the purchasing stockholders’ subsequent disposition of those shares, may have resulted in such an ownership change, or could result in an ownership change in the future. The Company completed a preliminary Code section 382 and 383 study from inception through December 31, 2020 and concluded that $ 1.8 million of federal and California net operating losses and $ 0.1 million of federal R&D credits will expire unused. The Company removed deferred tax assets for net operating loss of $ 0.6 million and research credits of $ 0.1 million from its deferred tax assets schedule and has recorded a corresponding decrease in the valuation allowance. The Company has not conducted a Sections 382 and 383 study after December 31, 2020. When such study is completed, the Company will adjust its deferred tax assets accordingly. Due to the existence of a full valuation allowance any subsequent ownership changes will not impact the Company’s effective tax rate. The Company had federal and California NOL carryforwards of approximately $ 200.9 million and $ 93.8 million, respectively, portions of which begin to expire in 2034 and 2036, respectively. Federal NOLs of $ 122.4 million carry forward indefinitely. As of D ecember 31, 2023, the Company had federal and California research and development (“R&D” tax) credit carryforwards of approximately $ 11.4 million, inclusive of the federal orphan drug tax credit carryforward, and $ 4.8 million, respectively. The federal R&D tax credit carryforwards will begin to expire in 2034, unless previously utilized. The California R&D tax credit carryforwards are available indefinitely. As of December 31, 2023, the Company also had federal orphan drug tax credit carryforwards of $ 2.2 million that will begin to expire in 2037. The Inflation Reduction Act 2022 which incorporates a Corporate Alternative Minimum Tax (CAMT) was signed on August 16, 2022. The changes will affect for the tax years beginning after December 31, 2022. The new tax will require companies to compute two separate calculations for federal income tax purposes and pay the greater of the new minimum tax or their regular tax liability. The Company will be monitoring the impacts of the act to determine if this will have an impact for the Company for years beginning after December 31, 2022. The act is not expected to have a material impact for the Company. The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. A reconciliation of the beginning and ending amount of unrecognized tax benefits for 2023 and 2022, excluding interest and penalties, is as follows (in thousands): December 31, December 31, Balance at beginning of the year $ 8,860 $ 8,235 Additions/(reductions) for tax positions - prior year 117 — Increase related to current year positions 840 625 Balance at the end of the year $ 9,817 $ 8,860 For the year ended December 31, 2023, the Company recognized interest and penalties of approximately $ 40,000 and zero , respectively, which are recorded in accrued expenses on the consolidated balance sheets. Interest and penalties are captured within the interest expense and other income (expense) lines, respectively, on the consolidated statements of operations and comprehensive loss. For the year ended December 31, 2022, the Company recognized interest and penalties of approximately $ 62,000 and $ 50,000 , respectively. The Company currently files income tax returns in California and with the U.S. Internal Revenue Service. The Company currently has no tax periods under examination by any jurisdiction. Due to the existence of net operating loss carryforwards, all tax periods from inception of the Company are open for examination by taxing authorities for all jurisdictions. Included in the balance of unrecognized tax benefits at December 31, 2023 is $ 8.3 million that, if recognized, would not impact the Company’s income tax expense (benefit) or effective tax rate as long as our deferred tax asset remains subject to a full valuation allowance. The Company does not expect any significant increases or decreases to our unrecognized tax benefits within the next 12 months.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events On January 29, 2024, the Company completed the January 2024 Registered Direct Offering which included the issuance and sale of an aggregate of 338,000 shares of the Company’s common stock at a purchase price of $ 10.075 per share in a registered direct offering priced at-the-market under Nasdaq rules. In addition, the offering included the issuance of 1,150,834 shares of common stock in the form of pre-funded warrants, 497,834 of which were subsequently exercised, with a purchase price of $ 10.074 per share and an exercise price of $ 0.001 (the “January 2024 Pre-Funded Warrants”). Additionally, the Company issued warrants to purchase up to 1,488,834 shares of common stock (the “January 2024 Common Stock Warrants”) with an exercise price of $ 9.95 per share. The January 2024 Common Stock Warrants will expire on July 29, 2027 , which is three and one-half years from the issuance date. Further, the Company issued warrants to designees of the placement agent to purchase up to 104,218 shares of common stock ("January 2024 Placement Agent Warrants") with an exercise price of $ 12.5938 per share. The January 2024 Placement Agent Warrants will expire on July 29, 2027 , which is three and one-half years following the commencement of sales in the January 2024 Registered Direct Offering. The Company received gross proceeds from the January 2024 Registered Direct Offering of $ 15.0 million with net proceeds of approximately $ 13.6 million after deducting $ 1.4 million in commissions and other transaction costs. In connection with the January 2024 Registered Direct Offering, the Company paid H.C. Wainwright & Co., LLC, as exclusive placement agent, an aggregate cash fee equal to 7.0 % of the gross proceeds received by the Company from the offering and a management fee equal to 1.0 % of the gross proceeds received by the Company from the offering. The Company also paid the placement agent $ 25,000 for non-accountable expenses, $ 50,000 for fees and expenses of legal counsel and other out-of-pocket expenses, and $ 15,950 for clearing fees. Additionally, the Company issued designees of the placement agent the January 2024 Placement Agent Warrants, equal to 7.0 % of the aggregate number of shares of common stock and pre-funded warrants placed in the offering.

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 Company’s consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).
Liquidity	Liquidity The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or amounts and classification of liabilities that may result from the outcome of this uncertainty. Management is required to perform a two-step analysis over its ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern (step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (step 2). The Company has experienced net losses and negative cash flows from operating activities since its inception, aside from the years ended December 31, 2021 and December 31, 2020 when net income was realized as a result of a gain in fair value recognized associated with the earn-out liability and revenue in connection with the Research Collaboration and License Agreement with Pfizer, respectively. The Company has an accumulated deficit of $ 179.4 million at December 31, 2023. For the year ended December 31, 2023, the Company had a net loss of $ 35.8 million and used $ 29.6 million in cash for operations. At December 31, 2023, the Company had cash and cash equivalents and short-term investments of $ 18.4 million. The Company anticipates that its expenses will increase significantly in connection with its ongoing activities to support its research and development efforts, and it expects to incur substantial operating losses and negative cash flows from operations for the foreseeable future. Management has prepared cash flow forecasts which indicate that based on the Company’s expected operating losses and negative cash flows, there is substantial doubt about the Company’s ability to continue as a going concern within twelve months from the date that these financial statements for the year ended December 31, 2023 are issued. The principal payments due under the Oxford Loans (as defined below), and the related accrued final payment, have been classified as current liabilities as of December 31, 2023, due to the considerations discussed above and the assessment that the material adverse change clause under the Oxford Loans is not within the Company’s control. The Company has not been notified of an event of default by the lender as of the date of issuance of these financial statements. The Company’s ability to continue as a going concern is dependent upon its ability to receive additional capital. Management intends to raise additional capital through equity offerings or other capital sources, including potential additional collaborations, licenses and other similar arrangements. Additionally, the Company may receive additional milestone payments from the Research Collaboration and License Agreement with Pfizer (described in Note 11), through the issuance of common stock under the equity purchase agreement (the "Purchase Agreement") with Lincoln Park Capital Fund, LLC ("Lincoln Park") (described in Note 8) or through the issuance of common stock under the at-the-market offering program (described in Note 8) with Cantor Fitzgerald & Co ("Cantor"). However, the Company may not be able to secure additional financing in a timely manner or on favorable terms, if at all, and may not receive any milestone payments. Without additional capital, the Company may be forced to delay, scale back or eliminate some of its research and development activities, or other operations and potentially delay product development in an effort to provide sufficient funds to continue its operations, or may be required to pursue merger or acquisition strategies, all of which could adversely affect the holdings or the rights of its stockholders.
Use of Estimates	Use of Estimates The Company’s consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of the Company’s consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimate in the Company’s consolidated financial statements relates to its clinical trial expense accruals. Management evaluates its estimates on an ongoing basis. Although these estimates are based on the Company’s historical experience, knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Cash, Cash Equivalents and Short-term Investments	Cash, Cash Equivalen ts and Short-term Investments Cash and Cash Equivalents The Company considers all highly liquid investments with insignificant interest rate risk and an original maturity of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist of money market funds and U.S. Treasury securities with an original maturity of less than three months at the date of purchase. Short-term Investments Short-term investments consist of U.S. Treasury securities, classified as available-for-sale securities and have maturities of greater than three months but less than one year. The Company has classified all of its available-for-sale securities as current assets on the balance sheets because these are considered highly liquid securities and are available for use in current operations. The Company carries these securities at fair value, and reports unrealized gains and losses as a separate component of accumulated other comprehensive income (loss). Amortization and accretion of any purchase premiums or discounts is included in interest income in the consolidated statements of operations and comprehensive loss.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of all cash equivalents, prepaid expenses and other assets, accounts payable and accrued liabilities are reasonable estimates of their fair value because of the short-term nature of these items. Based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes the fair value of the term loans approximate their carrying value (see Note 6).
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash and cash equivalents and short-term investments. The Company maintains deposits in a federally insured major financial institution in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institution in which those deposits are held. The Company is subject to a number of risks similar to other biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of current or future preclinical studies or clinical trials, reliance on third parties or partners to conduct its clinical trials, the need to obtain regulatory and marketing approvals for its drug candidates or to rely on partners to do so, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of its drug candidates, the right to develop and commercialize drug candidates pursuant to the terms and conditions of the licenses granted to the Company, protection of proprietary technology, the ability to make milestone, royalty or other payments due under any license or collaboration agreements, and the need to secure and maintain adequate manufacturing arrangements with third parties. If the Company does not successfully commercialize or partner any of its drug candidates, it will be unable to generate product revenue or achieve profitability.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost and depreciated or amortized using the straight-line method over the estimated useful lives of the assets (generally three to five years , or the remaining term of the lease for leasehold improvements , whichever is shorter) and generally consist of laboratory equipment, computer and office equipment, furniture and fixtures, and leasehold improvements. Repairs and maintenance costs are charged to expense as incurred.
Long-Lived Assets	Long-Lived Assets The Company regularly reviews the carrying value and estimated lives of all of its long-lived assets, including property and equipment to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. Should an impairment exist, the impairment loss would be measured based on the excess over the carrying amount of the asset’s fair value. The Company has no t recognized any impairment losses from inception through December 31, 2023.
Leases	Leases At the commencement date of a lease, the Company recognizes lease liabilities which represent its obligation to make lease payments, and right-of-use assets ("ROU assets") which represent its right to use the underlying asset during the lease term. The lease liability is measured at the present value of lease payments over the lease term. As the Company’s leases typically do not provide an implicit rate, the Company uses an incremental borrowing rate based on the information available at the lease commencement date. The ROU asset is measured at cost, which includes the initial measurement of the lease liability and initial direct costs incurred by the Company and excludes lease incentives. ROU assets are recorded in operating lease ROU assets and lease liabilities are recorded in operating lease liabilities, current and noncurrent in the balance sheets.
Grant Revenue	Grant Revenue The Company had grant revenues in 2022 derived from a grant with the Defense Advanced Research Projects Agency (“DARPA”) through the University of California, San Francisco (“UCSF”). The Company recognized DARPA grant revenue as reimbursable grant costs are incurred up to pre-approved award limits within the budget period. The costs associated with these reimbursements are reflected as a component of research and development expense in the accompanying 2022 consolidated statements of operations and comprehensive loss. Billings in excess of receipts are included as a receivable recorded within prepaid expenses and other current assets on the consolidated balance sheets.
Research and Development Costs	Research and Development Costs Research and development expenses primarily consist of costs associated with the preclinical and clinical development of the Company’s product candidates. Research and development costs are expensed as incurred.
Clinical Trial Accruals and Preclinical Studies	Clinical Trial Accruals and Preclinical Studies The Company records expenses resulting from our obligations under contracts with vendors and consultants, CROs and clinical sites in connection with conducting clinical trials and preclinical studies. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company reflects clinical trial and preclinical study expenses in the financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of the clinical trial or preclinical study as measured by the timing of various aspects of the clinical trial, preclinical study, or related activities. The Company determines accrual estimates based on the underlying contracts, correspondence with clinical and other key personnel and third-party service providers as to the progress of the clinical trials, preclinical studies, or other services being conducted, and amounts invoiced or paid to date. During the course of a clinical trial or preclinical study, the Company adjusts the rate of expense recognition if actual results differ from estimates.
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.
Revenue Recognition	Revenue Recognition The Company evaluates collaboration arrangements to determine whether units of account within the collaboration arrangement exhibit the characteristics of a vendor and customer relationship. For arrangements and units of account where a customer relationship exists, the Company applies the revenue recognition guidance. The Company recognizes revenue upon the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies the performance obligations. At contract inception, the Company assesses the goods or services promised within each contract and assesses whether each promised good or service is distinct and determines those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, upfront fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition on a prospective basis. For research and development services performed under a collaboration agreement in which the performance obligation is satisfied over time, the Company measures the progress of the activities using an input method. The input methods used are based on the effort expended or costs incurred toward the satisfaction of the related performance obligation. The Company estimates the amount of effort expended, including the time the Company estimates it will take to complete the activities, or costs incurred 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 consideration allocated to the research and development services to determine the amount of revenue recognized each period. This approach requires estimates and the use of significant judgement. If the estimates or judgements change over the course of the collaboration, they may affect the timing and amount of revenue recognized in the current and future periods.
Milestones	Milestones At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company or the Company’s collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the Company’s estimate of the overall transaction price. Any such adjustments are allocated on a cumulative catch-up basis to satisfied and partially satisfied performance obligations, with the consideration allocated to an ongoing performance obligation being recognized over the period of performance.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, 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. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. As of December 31, 2023 and 2022, the Company maintained valuation allowances against its deferred tax assets as the Company concluded it had not met the “more likely than not” to be realized threshold. Changes in the valuation allowance when they are recognized in the provision for income taxes may result in a change in the estimated annual effective tax rate. The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more likely than not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Comprehensive Loss	Comprehen sive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company presents comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment.
Stock-Based Compensation Expense	Stock-Based Compensation Expense Stock-based compensation expense represents the cost of the grant date fair value of employee stock option grants recognized over the requisite service period of the awards (usually the vesting period) on a straight- line basis. The Company estimates the fair value of stock option grants using the Black-Scholes option-pricing model. The Company accounts for stock options granted to non-employees using the fair value approach. The Black-Scholes option-pricing model requires the use of subjective assumptions, including the risk- free interest rate, the expected stock price volatility, the expected term of stock options, and the expected dividend yield. The Company has limited historical stock option activity and therefore estimates the expected term of stock options granted using the simplified method, which represents the average of the contractual term of the stock option and its weighted-average vesting period. The fair value of the underlying common stock used within the Black-Scholes option-pricing model is based on the closing price of common stock on the date of grant.
Public and Private Placement Warrants	Public and Private Placement Warrants Upon completion of the Business Combination, the Company assumed public and private placement warrants that were issued by LWAC in connection with their initial public offering in January 2021 whereby holders of the public and private placement warrants are entitled to acquire common stock of the Company. The Company has concluded that the public warrants are equity-classified. Since the settlement value of the private placement warrants is dependent, in part, on who holds the warrants at the time of settlement, they are not considered indexed to the Company's stock and are therefore recorded as liabilities. Warrants classified as liabilities are recorded at their estimated fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized in other income (expense), net in the accompanying consolidated statements of operations and comprehensive loss. The Company estimates the fair value of these warrants using the Black-Scholes option pricing model.
Common Stock and Placement Agent Warrants	Common Stock and Placement Agent Warrants In May 2023 and June 2023, the Company completed two separate registered direct offerings whereby common stock warrants and placement agent warrants were issued with the right to acquire common stock of the Company. In order to determine the appropriate accounting treatment for the warrants, the Company considered the indexation guidance under Accounting Standards Codification ("ASC") 815-40. The Company has concluded that the common stock warrants and placement agent warrants issued in the May 2023 and June 2023 registered direct offerings are equity classified as they are considered indexed to the Company's stock and do not contain any settlement provisions that would preclude equity classification.
Earn-out Shares	Earn-Out Shares In accordance with the Merger Agreement, 200,000 shares ("Earn-Out Shares") were contingently issuable to Old eFFECTOR stockholders and option holders upon the occurrence of the Triggering Event, defined within the Merger Agreement as the date on which the common stock price equals or exceeds $ 500.00 over at least 20 trading days out of a 30 consecutive trading day period during the two-year period following the close date of the Business Combination. The estimated fair value of the Earn-Out Shares was determined using a Monte Carlo simulation valuation model using a distribution of potential outcomes on a monthly basis over the earn-out period using the most reliable information available. The Company determined that the contingent obligation to issue Earn-Out Shares to existing Old eFFECTOR stockholders was not indexed to the Company's stock under ASC 815-40 and therefore equity treatment was precluded. The Triggering Event that would determine the issuance of the Earn-Out Shares included terms that were not solely indexed to our common stock, and as such liability classification was required. Equity-linked instruments classified as liabilities are recorded at their estimated fair value on the date of issuance and are revalued at each subsequent balance sheet date, with fair value changes recognized in other income (expense), net in the accompanying consolidated statements of operations and comprehensive loss. The Company has determined that the contingent obligation to issue Earn-Out Shares to existing Old eFFECTOR option holders falls within the scope of ASC 718, Share-based Compensation, because the option holders were required to continue providing service until the occurrence of the Triggering Event. The fair value of the option holder Earn-Out Shares was recorded as share-based compensation over the derived service period of the Monte Carlo simulation valuation model, recognized in research and development and general and administrative expense in the consolidated statements of operations and comprehensive loss. The Triggering Event did not occur during the two-year period following the close date of the Business Combination and the achievement period for the earn-out expired on August 25, 2023. As such, the Old eFFECTOR stockholders and option holders are no longer eligible to receive Earn-Out shares as of August 25, 2023.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board ("FASB") or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes, based on its preliminary assessment, that the impact of recently issued standards that are not yet effective will not have a material impact on their financial position or results of operations upon adoption. In November 2023, the Financial Accounting Standards Board (“FASB”) issued updated accounting guidance related to annual and interim segment disclosures. The updated accounting guidance, among other things, requires disclosure of certain significant segment expenses. We will adopt the updated accounting guidance in our Annual Report on Form 10-K for the year ended December 31, 2024. We do not expect impact from the adoption of the new accounting guidance will have material impact to our segment disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. The update requires a public business entity to disclose, on an annual basis, a tabular rate reconciliation using both percentages and currency amounts, broken out into specified categories with certain reconciling items further broken out by nature and jurisdiction to the extent those items exceed a specified threshold. In addition, all entities are required to disclose income taxes paid, net of refunds received disaggregated by federal, state/local, and foreign and by jurisdiction if the amount is at least 5% of total income tax payments, net of refunds received. Adoption of the ASU allows for either the prospective or retrospective application of the amendment and is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The Company has not yet completed its assessment of the impact of ASU 2023-09 on the Company’s Consolidated Financial Statements. We do not believe that any other recently issued, but not yet effective accounting pronouncements, if adopted, would have a material impact on our consolidated financial statements or disclosures.
Net Income (Loss) Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares plus the potential dilutive effects of potential dilutive securities outstanding during the period. Potential dilutive securities are excluded from diluted earnings or loss per share if the effect of such inclusion is antidilutive. The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Potentially dilutive securities as of December 31, 2023 and 2022 are as follows (in common stock equivalent shares, each as adjusted to reflect the Reverse Stock Split): For the Year Ended December 31, 2023 2022 Common stock warrants 768,592 — Placement agent warrants 53,799 — Public warrants 233,332 233,332 Private placement warrants 7,266 7,266 Earn-Out Shares — 200,000 Unvested sponsor shares 12,000 12,000 Stock options outstanding 480,875 349,495 Total 1,555,864 802,093

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities	Potentially dilutive securities as of December 31, 2023 and 2022 are as follows (in common stock equivalent shares, each as adjusted to reflect the Reverse Stock Split): For the Year Ended December 31, 2023 2022 Common stock warrants 768,592 — Placement agent warrants 53,799 — Public warrants 233,332 233,332 Private placement warrants 7,266 7,266 Earn-Out Shares — 200,000 Unvested sponsor shares 12,000 12,000 Stock options outstanding 480,875 349,495 Total 1,555,864 802,093

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Summary of assets and liabilities measured at fair value on a recurring basis	The following table summarizes the Company’s assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy as of December 31, 2023 and December 31, 2022 (in thousands): Fair Value Measurements Using December 31, Quoted Prices Significant Significant 2023 Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 10,887 $ 10,887 $ — $ — U.S. Treasury securities 3,988 — 3,988 — Short-term investments: U.S. Treasury securities 3,495 — 3,495 — Total assets $ 18,370 $ 10,887 $ 7,483 $ — Liabilities Private placement warrant liability $ 40 $ — $ — $ 40 Total liabilities $ 40 $ — $ — $ 40 Fair Value Measurements Using December 31, Quoted Prices Significant Significant 2022 Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 8,708 $ 8,708 $ — $ — Short-term investments: U.S. Treasury securities 17,602 — $ 17,602 — Total assets $ 26,310 $ 8,708 $ 17,602 $ — Liabilities Private placement warrant liability $ 40 $ — $ — $ 40 Earn-out liability 6 — — 6 Total liabilities $ 46 $ — $ — $ 46
Summary of Short term Investment	The following tables summarize the Company’s short-term investments accounted for as available-for-sale securities as of December 31, 2023 and December 31, 2022 (in thousands): December 31, 2023 Maturity Amortized Unrealized Unrealized Estimated (in years) Cost Gains Losses Fair Value U.S. Treasury securities 1 year or less $ 3,495 $ — $ — $ 3,495 $ 3,495 $ — $ — $ 3,495 December 31, 2022 Maturity Amortized Unrealized Unrealized Estimated (in years) Cost Gains Losses Fair Value U.S. Treasury securities 1 year or less $ 17,620 $ 1 $ ( 19 ) $ 17,602 $ 17,620 $ 1 $ ( 19 ) $ 17,602
Private Placement Warrants Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Summary of fair value measurements inputs	The following key assumptions were used in determining the fair value of the private placement warrant liability valued using the Black-Scholes option pricing model as of December 31, 2023 and December 31, 2022: December 31, December 31, Common stock price $ 11.69 $ 10.69 Expected volatility 125.0 % 125.0 % Risk-free interest rate 4.1 % 4.2 % Expected term (in years) 2.7 3.7 Expected dividend yield — —
Summary of change in fair value of derivative warrant liabilities	The following table presents activity for the private placement warrant liability measured at fair value using significant unobservable Level 3 inputs during the year ended December 31, 2023 (in thousands): Private Placement Warrant Liability Balance at December 31, 2022 40 Change in fair value — Balance at December 31, 2023 $ 40

Property and Equipment , net (T

Property and Equipment , net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment ,net	Property and equipment, net consists of the following (in thousands): December 31, December 31, Lab equipment $ 30 $ 30 Computer and office equipment 154 149 Furniture and fixtures 78 61 Leasehold improvements 188 188 Construction in process 14 29 464 457 Less accumulated depreciation and amortization ( 324 ) ( 216 ) $ 140 $ 241

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): December 31, December 31, Employee compensation $ 1,587 $ 1,385 Research and development 1,036 1,206 Professional and outside services 75 112 Interest 223 197 Other — 468 $ 2,921 $ 3,368

Term Loans (Tables)

Term Loans (Tables)	12 Months Ended
	Dec. 31, 2023
Notes and Loans Payable, by Type, Current and Noncurrent [Abstract]
Schedule of Principal Future Payments of Term Loans	Based on the outstanding principal amounts for the Company’s Term A Loans, the following table sets forth by year the Company’s required future principal payments as of December 31, 2023 (in thousands): As of December 31, 2023 2024 $ 5,555 2025 6,667 2026 6,667 2027 1,111 Required future principal payments $ 20,000 Unamortized debt discount ( 615 ) Current term loans, net as of December 31, 2023 $ 19,385

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2023
Class of Warrant or Right [Line Items]
Summary of Public and private placement warrants outstanding.	The following table summarizes the number of outstanding public warrants and private placement warrants and the corresponding exercise price as of December 31, 2023 and December 31, 2022: December 31, December 31, Exercise Price Expiration Date Public warrants 233,332 233,332 $ 287.50 August 24, 2026 Private placement warrants 7,266 7,266 $ 287.50 August 24, 2026
Warrant [Member]
Class of Warrant or Right [Line Items]
Summary of Public and private placement warrants outstanding.	The following table summarizes the number of outstanding common stock warrants and placement agent warrants and the corresponding exercise price as of December 31, 2023 and December 31, 2022: December 31, December 31, Exercise Price Expiration Date May 2023 Common Stock Warrants 458,015 — $ 13.25 November 30, 2028 May 2023 Placement Agent Warrants 32,060 — $ 20.47 May 26, 2028 June 2023 Common Stock Warrants 310,577 — $ 25.00 December 8, 2028 June 2023 Placement Agent Warrants 21,739 — $ 35.1575 June 6, 2028

Preferred Stock and Stockhold_2

Preferred Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Summary of option activity under the company's plans	A summary of the Company’s stock option activity under the plans is as follows (in thousands, except share and per share amounts and years): Shares Weighted- Weighted- Aggregate Outstanding at December 31, 2022 349,495 $ 68.23 7.4 $ — Granted 151,589 13.01 9.1 Exercised ( 3,590 ) 13.00 — Cancelled or forfeited ( 16,619 ) 55.70 6.6 Outstanding at December 31, 2023 480,875 $ 51.67 7.3 $ — Vested and exercisable at December 31, 2023 292,803 $ 57.64 6.3 $ —
Schedule of assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock option grants.	The assumptions used in t he Black-Scholes option pricing model to determine the fair value of the stock option grants were as follows: Year Ended December 31, 2023 2022 Risk-free interest rate 3.6 % - 4.4 % 1.7 % - 4.1 % Expected volatility 84 % - 85 % 82 % - 86 % Expected term (in years) 5.3 - 6.1 5.2 - 6.1 Expected dividend yield 0 % 0 %
Schedule of Common Stock, Reserved for Future Issuance	Common stock reserved for future issuance consists of the following as of December 31, 2023: December 31, Stock options issued and outstanding 480,875 Public warrants issued and outstanding 233,332 Private placement warrants issued and outstanding 7,266 Common stock warrants issued and outstanding 768,592 Placement agent warrants issued and outstanding 53,799 Unvested sponsor shares 12,000 Authorized for future stock awards or option grants 96,449 Authorized for future issuances under the ESPP 59,144 Total 1,711,457

Earn-out Shares (Tables)

Earn-out Shares (Tables)	12 Months Ended
	Dec. 31, 2023
Earn out Share [Abstract]
Schedule Of Estimated Fair Value Of The Earn Out Shares	The fair value per share of the Earn-Out Shares was less than $ 0.01 as of December 31, 2022. The fair value was determined using a Monte Carlo simulation valuation model using a distribution of potential outcomes on a monthly basis over the earn-out period using the most reliable information available. Assumptions used in the valuation were as follows: December 31, Stock price $ 10.69 Expected volatility 115.0 % Risk-free interest rate 4.8 % Forecast period (in years) 0.6 Cost of equity 20.0 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Supplemental Balance sheet Information related to Leases	The following table summarizes supplemental balance sheet information related to leases as of December 31, 2023 and December 31, 2022 (in thousands): December 31, December 31, Assets: Operating lease right-of-use assets $ 53 $ 111 Total right-of-use assets 53 111 Liabilities Operating lease liabilities, current 60 60 Operating lease liabilities, non-current — 60 Total operating lease liabilities $ 60 $ 120
Schedule of Future Minimum Rental Payments for Operating Leases	As of December 31, 2023, the future minimum annual lease payments under the existing operating leases were as follows (in thousands, except for weighted-average remaining lease term and weighted-average discount rate): 2024 62 Total remaining lease payments 62 Less: imputed interest ( 2 ) Total operating lease liabilities 60 Less: current portion ( 60 ) Long-term operating lease liabilities $ - Weighted-average remaining lease term ( in years ) 0.83 Weighted-average discount rate 8 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Net Deferred Tax Assets Components	Significant components of the Company’s net deferred tax assets are summarized as follows (in thousands): December 31, December 31, Deferred tax assets: Net operating loss carryforwards $ 46,365 $ 42,243 Intangibles 174 189 Research and development capitalization 6,525 3,839 Accrued compensation 2,070 2,282 Credits 9,395 8,013 Fixed assets 21 10 Other, net 99 88 Right-of-use liability 13 25 Deferred tax assets 64,662 56,689 Deferred tax liabilities: Right-of-use asset ( 11 ) ( 23 ) Deferred tax liabilities ( 11 ) ( 23 ) Net deferred tax assets 64,651 56,666 Valuation allowance ( 64,651 ) ( 56,666 ) Net deferred tax assets $ — $ —
Schedule of Components of Income Tax Expense (Benefit)	A reconciliation of the income tax computed at the federal statutory tax rate to the expense (benefit) for income taxes for the years ended December 31, 2023 and 2022 is as follows (in thousands ): December 31, December 31, Tax at statutory rate $ ( 7,520 ) $ ( 4,760 ) State income taxes, net of federal benefits — ( 2,076 ) Change in valuation allowance 7,990 7,726 Uncertain tax positions 793 586 Gain on change in fair value of earn-out liability ( 1 ) ( 2,546 ) Permanent differences and other 974 281 Transaction costs 6 244 Capitalized R&D — 3,381 LWAC net operating loss ( 259 ) ( 1,370 ) Credits ( 1,983 ) ( 1,466 ) Income tax expense $ — $ —
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits for 2023 and 2022, excluding interest and penalties, is as follows (in thousands): December 31, December 31, Balance at beginning of the year $ 8,860 $ 8,235 Additions/(reductions) for tax positions - prior year 117 — Increase related to current year positions 840 625 Balance at the end of the year $ 9,817 $ 8,860

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares	Jan. 09, 2024 $ / shares
Subsidiary Sale Of Stock [Line Items]
Date of incorporation	Oct. 02, 2020
Place of incorporation	DE
Accumulated deficit	$ 179,377	$ 143,566
Cash from operation	29,600
Cash and cash equivalents and short-term investments	18,400
Net loss	(35,811)	(22,665)
Cash and cash equivalents	$ 14,875	$ 8,708
Common stock price per share | $ / shares	$ 0.0001	$ 0.0001
Common Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Common stock price per share | $ / shares	$ 0.0001		$ 0.0001
Minimum | Common Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Common shared Issused , Reverse Stock Split | shares	1,000,000,000
Maximum | Common Stock [Member]
Subsidiary Sale Of Stock [Line Items]
Common shared Issused , Reverse Stock Split | shares	40,000,000
Locust Walk Acquisition Corp [Member]
Subsidiary Sale Of Stock [Line Items]
Conversion of outstanding common and preferred shares into common shares	0.09657

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) Segment $ / shares shares	Dec. 31, 2022 $ / shares shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Property and equipment useful lives	3 years
Impairment losses | $	$ 0
Operating segments | Segment	1
Common stock, shares issued | shares	2,994,679	1,679,602
Common stock price per share | $ / shares	$ 0.0001	$ 0.0001
Consecutive trading days required for entitlement of common stock	30 days
Maximum
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Property and equipment useful lives	5 years
Leasehold Improvements
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	Property, Plant and Equipment, Net
Earn-Out Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock, shares issued | shares	200,000
Common stock price per share | $ / shares	$ 500
Trading days required for entitlement of common stock	20 days
Consecutive trading days required for entitlement of common stock	30 days

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities (Detail) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	1,555,864	802,093
Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	768,592	0
Placement Agent Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	53,799	0
Public warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	233,332	233,332
Private Placement [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	7,266	7,266
Earn-Out Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	0	200,000
Unvested Sponsor Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	12,000	12,000
Stock Options Outstanding [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially Dilutive Securities (in common stock equivalent shares)	480,875	349,495

Fair Value Measurementsn - Addi

Fair Value Measurementsn - Additional Information (Detail) - Fair Value, Inputs, Level 1, 2 and 3 [Member] - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, net derivative asset (liability) measured on recurring basis, unobservable inputs reconciliation, transfers, net	$ 0	$ 0
Money Market Funds, at Carrying Value	10,900,000	8,700,000
Interest Receivable	$ 52,000	$ 27,000

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets And Liabilities Measured At Fair Value On Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Liabilities
Earn-out liability	$ 0	$ 6
Fair Value, Recurring
Assets
Total assets	18,370	26,310
Liabilities
Earn-out liability		6
Total liabilities	40	46
Fair Value, Recurring | Private Placement Warrant Liability
Liabilities
Warrant liability	40	40
Fair Value, Recurring | Fair Value Inputs Level 1
Assets
Total assets	10,887	8,708
Liabilities
Total liabilities	0	0
Fair Value, Recurring | Fair Value Inputs Level 2
Assets
Total assets	7,483	17,602
Liabilities
Total liabilities	0	0
Fair Value, Recurring | Fair Value Inputs Level 3
Assets
Total assets	0	0
Liabilities
Earn-out liability		6
Total liabilities	40	46
Fair Value, Recurring | Fair Value Inputs Level 3 | Private Placement Warrant Liability
Liabilities
Warrant liability	40	40
Fair Value, Recurring | Money Market Funds
Assets
Money market funds	10,887	8,708
Fair Value, Recurring | Money Market Funds | Fair Value Inputs Level 1
Assets
Money market funds	10,887	8,708
Fair Value, Recurring | US Treasury Securities [Member]
Assets
U.S. Treasury securities	3,988
Fair Value, Recurring | US Treasury Securities [Member] | Fair Value Inputs Level 2
Assets
U.S. Treasury securities	3,988
Fair Value, Recurring | US Treasury Securities [Member] | Short-Term Investments [Member]
Assets
U.S. Treasury securities	3,495	17,602
Fair Value, Recurring | US Treasury Securities [Member] | Short-Term Investments [Member] | Fair Value Inputs Level 2
Assets
U.S. Treasury securities	$ 3,495	$ 17,602

Fair Value Measurements - Short

Fair Value Measurements - Short Term Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 3,495	$ 17,620
Unrealized Gains	0	1
Unrealized Losses	0	(19)
Estimated Fair Value	$ 3,495	$ 17,602
US Treasury Securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Maturity (in years)	1 year	1 year
Amortized Cost	$ 3,495	$ 17,620
Unrealized Gains	0	1
Unrealized Losses	0	(19)
Estimated Fair Value	$ 3,495	$ 17,602

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of fair value measurements inputs of private placement warrant liability (Detail) - Private Placement Warrant Liability	Dec. 31, 2023 USD ($) yr	Dec. 31, 2022 yr USD ($)
Common Stock Price
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input | $	11.69	10.69
Expected volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input	125	125
Risk-free interest rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input	4.1	4.2
Expected term (in years)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input | yr	2.7	3.7
Expected dividend yield
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input	0	0

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of change in fair value of private placement warrant liability (Detail) - Private Placement Warrant Liability $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value, Beginning Balance	$ 40
Change in fair value	0
Fair value, Ending Balance	$ 40

Property and Equipment, net - S

Property and Equipment, net - Summary of Property and Equipment, net (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	$ 464	$ 457
Less accumulated depreciation and amortization	(324)	(216)
Property and Equipment, Net	140	241
Lab Equipment [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	30	30
Computer And Office Equipment [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	154	149
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	78	61
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	188	188
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Property and Equipment, Gross	$ 14	$ 29

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 111,000	$ 53,000

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Employee compensation	$ 1,587	$ 1,385
Research and development	1,036	1,206
Professional and outside services	75	112
Interest	223	197
Other	0	468
Accrued Liabilities, Current	$ 2,921	$ 3,368

Term Loans - Additional Informa

Term Loans - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Feb. 22, 2022 USD ($)	Mar. 31, 2021 USD ($) Tranche	Dec. 31, 2023 USD ($) $ / shares shares
Debt Instrument [Line Items]
Outstanding principal, Term loans			$ 19,385
Extended cut off date before which the interest on term loan shall be paid	Mar. 01, 2024
Borrowed Term Loan			$ 20,000
Loan and Security Agreement [Member] | Less Than One Year From The Date Of Loan Agreement [Member]
Debt Instrument [Line Items]
Prepayment fee as a percentage of the outstanding principal			3%
Loan and Security Agreement [Member] | Greater Than One Year And Less Than Two Years From The Date Of Loan Agreement [Member]
Debt Instrument [Line Items]
Prepayment fee as a percentage of the outstanding principal			2%
Loan and Security Agreement [Member] | Later Than Two Years And Not Later Than Three Years From The Date Of Loan Agreement [Member]
Debt Instrument [Line Items]
Prepayment fee as a percentage of the outstanding principal			1%
Loan and Security Agreement [Member] | Later Than Three Years From The Date Of Loan Agreement [Member]
Debt Instrument [Line Items]
Prepayment fee as a percentage of the outstanding principal			0%
Loan and Security Agreement [Member] | Oxford Finance LLC [Member]
Debt Instrument [Line Items]
Number of tranches | Tranche		2
Debt instrument, face amount		$ 30,000
Number of days within which a portion of term loan will be available subject to achievement of milestone	45 days
Long term debt variable interest rate percentage			7.70%
Loan and Security Agreement [Member] | Prime Rate [Member] | Oxford Finance LLC [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate spread			4.45%
Loan and Security Agreement [Member] | Warrants To Purchase Series C Redeemable Convertible Stock | Oxford Finance LLC [Member]
Debt Instrument [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 133.25
Number of shares subject to each warrant | shares			1,503
Loan and Security Agreement [Member] | Debt Instrument, Term Loan A [Member] | Oxford Finance LLC [Member]
Debt Instrument [Line Items]
Debt Instrument, Description	In connection with the amendment, the maturity of the Term A Loans was extended from March 18, 2026 to February 1, 2027.
Debt Instrument, Discount			$ 1,600
Outstanding principal, Term loans		$ 20,000	20,000
Amortization of debt discount			2,900
Term loan final payment as a percentage of the amount funded		5.50%
Borrowed Term Loan		$ 20,000	$ 19,400
Loan and Security Agreement [Member] | Debt Instrument, Term Loan B [Member]
Debt Instrument [Line Items]
Additional term Loan	$ 10,000
Loan and Security Agreement [Member] | Debt Instrument, Term Loan B [Member] | Less Than One Year From The Date Of Loan Agreement [Member]
Debt Instrument [Line Items]
Loan initiation date	Jun. 30, 2023
Loan and Security Agreement [Member] | Debt Instrument, Term Loan B [Member] | Oxford Finance LLC [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 10,000

Term Loans - Schedule of Princi

Term Loans - Schedule of Principal Future Payments of Term Loans (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Notes and Loans Payable, by Type, Current and Noncurrent [Abstract]
2024	$ 5,555
2025	6,667
2026	6,667
2027	1,111
Required future principal payments	20,000
Unamortized debt discount	(615)
Current term loans, net as of December 31, 2023	$ 19,385

Warrants - Additional Informati

Warrants - Additional Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class of Warrant or Right [Line Items]
Warrants and rights outstanding, term	5 years
Stock option exercises, net, shares	3,590
Public Warrants and Private Placement Warrants [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 287.5
Class of warrants, redemption price per unit	$ 0.25
Class of warrants, redemption notice period	30 days
Share price	$ 450
Number of consecutive trading days for determining share price	20 days
Number of trading days to determine share price	30 days
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 287.5
May 2023 Registered Direct Offering
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.025
Number of warrants	270,015
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.025
Pre-funded warrants with a purchase price	16.35
June 2023 Registered Direct Offering
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.025
Number of warrants	72,578
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.025
Pre-funded warrants with a purchase price	28.1
May 2023 Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 13.25
Number of warrants	458,015	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 13.25
Expiration date	Nov. 30, 2028
May 2023 Placement Agent Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 20.47
Number of warrants	32,060	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 20.47
Expiration date	May 26, 2028
June 2023 Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 25
Number of warrants	310,577	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 25
Expiration date	Dec. 08, 2028
June 2023 Placement Agent Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 35.1575
Number of warrants	21,739	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 35.1575
Expiration date	Jun. 06, 2028

Warrants - Schedule of Public a

Warrants - Schedule of Public and private placement warrants outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Public Warrants [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	233,332	233,332
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 287.5
Expiration date	Aug. 24, 2026
Private Placement Warrants [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	7,266	7,266
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 287.5
Expiration date	Aug. 24, 2026
May 2023 Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	458,015	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 13.25
Expiration date	Nov. 30, 2028
May 2023 Placement Agent Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	32,060	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 20.47
Expiration date	May 26, 2028
June 2023 Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	310,577	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 25
Expiration date	Dec. 08, 2028
June 2023 Placement Agent Warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	21,739	0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 35.1575
Expiration date	Jun. 06, 2028

Preferred Stock and Stockhold_3

Preferred Stock and Stockholders' Equity - Additional Information (Detail)				12 Months Ended
		Sep. 30, 2022 USD ($)	Jan. 24, 2022 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) TradingDays $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Aug. 25, 2021 shares	Aug. 24, 2021 shares
Class Of Stock [Line Items]
Share purchases under the Purchase Agreement | shares				0
Common stock value issued	[1]			$ 0	$ 0
Common stock, shares issued | shares				2,994,679	1,679,602
Proceeds from exercise of common stock options and warrants				$ 56,000	$ 3,000
Preferred stock, shares authorized | shares				100,000,000	100,000,000
Preferred stock, par value | $ / shares				$ 0.0001	$ 0.0001
Preferred stock, shares issued | shares				0	0
Preferred stock, shares outstanding | shares				0	0
Stock options outstanding | shares				480,875	349,495
Option, exercise price range, lower range limit | $ / shares				$ 100
Option, exercise price range, upper range limit | $ / shares				$ 110
Share-based payment award, expiration period				5 years
Fair value of vested option				$ 5,000,000
Share-based payment arrangement, expense				4,600,000	$ 5,000,000
Unrecognized compensation cost related to outstanding employee options				$ 4,600,000
Expected term (in years)				2 years 2 months 12 days
Unrecognized compensation cost related to outstanding nonemployee options				$ 900,000
Outstanding non employee expense expected period				8 months 12 days
Employee Option [Member]
Class Of Stock [Line Items]
Weighted-average grant date fair value | $ / shares				$ 9.39
Non-Employee Option [Member]
Class Of Stock [Line Items]
Weighted-average grant date fair value | $ / shares				$ 9.56
Maximum [Member]
Class Of Stock [Line Items]
Expected term (in years)				6 years 1 month 6 days	6 years 1 month 6 days
Minimum [Member]
Class Of Stock [Line Items]
Expected term (in years)				5 years 3 months 18 days	5 years 2 months 12 days
2013, Equity Incentive Plan
Class Of Stock [Line Items]
Stock options outstanding | shares				130,694		156,781
2021, Equity Incentive Plan
Class Of Stock [Line Items]
Number of shares reserved for future issuance | shares				96,449
Shares authorized | shares				446,630
Shares purchased for award | shares				375,506
Intrinsic value of options exercised				$ 0	$ 0
2021 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Shares fair market value percentage							85%
Number of shares reserved for future issuance | shares				59,144			35,200
Increase in reserved shares, percentage							1%
2021 Employee Stock Purchase Plan [Member] | Maximum [Member]
Class Of Stock [Line Items]
Number of shares reserved for future issuance | shares							600,000
ATM Offering Program [Member]
Class Of Stock [Line Items]
Payments of commission percentage		3%
Common stock, shares issued | shares				537,200	19,157
Shares Issued Price Per Share | $ / shares				$ 13.48	$ 15.03
Proceeds from exercise of common stock options and warrants				$ 7,200,000	$ 300,000
Temporary equity underwriting discounts, commissions and fees				$ 400,000	$ 200,000
ATM Offering Program [Member] | Maximum [Member]
Class Of Stock [Line Items]
Common stock value issued		$ 0
May 2023 Register Direct Offering [Member]
Class Of Stock [Line Items]
Common stock, shares issued | shares				188,000
Shares Issued Price Per Share | $ / shares				$ 16.375
Proceeds from exercise of common stock options and warrants				$ 7,500,000
Net proceed				6,700,000
Amortization of sales commissions				$ 800,000
May 2023 Register Direct Offering [Member] | Private Placement [Member] | H.C. Wainwright & Co [Member]
Class Of Stock [Line Items]
Managemengt fees percentage				1%
Gross proceed				7%
Costs and expenses				$ 75,000,000
Clearing fees				$ 15,950,000
June 2023 Registered Direct Offering
Class Of Stock [Line Items]
Common stock, shares issued | shares				238,000
Shares Issued Price Per Share | $ / shares				$ 28.125
Proceeds from exercise of common stock options and warrants				$ 8,700,000
Net proceed				7,800,000
Amortization of sales commissions				$ 900,000
June 2023 Registered Direct Offering | Private Placement [Member] | H.C. Wainwright & Co [Member]
Class Of Stock [Line Items]
Managemengt fees percentage				1%
Gross proceed				7%
Costs and expenses				$ 50,000,000
Clearing fees				$ 15,950,000
Sponsor Shares [Member]
Class Of Stock [Line Items]
Stock options outstanding | shares				162,250
Share based compensation options vesting shares | shares				12,000
Sponsor Shares [Member] | Maximum [Member]
Class Of Stock [Line Items]
Trading days | TradingDays				30
Sponsor Shares [Member] | Minimum [Member]
Class Of Stock [Line Items]
Trading days | TradingDays				20
Holder of More Than 10% [Member]
Class Of Stock [Line Items]
Option, exercise price range, lower range limit | $ / shares				$ 10
Common Stock [Member] | 2021 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Stock issued under employee stock purchase plans | shares				5,694	3,433
Common Stock [Member] | Sponsor Shares [Member]
Class Of Stock [Line Items]
Shares Issued Price Per Share | $ / shares				$ 375
Purchase Agreement [Member]
Class Of Stock [Line Items]
Other expense relating to the commitment fee			$ 800,000
Lincoln Park [Member]
Class Of Stock [Line Items]
Purchase Agreement			36 months
Initial purchase amount			$ 3,000,000
Initial purchase number of shares | shares			22,304
Shares issued, commitment shares | shares			5,717
Lincoln Park [Member] | Maximum [Member]
Class Of Stock [Line Items]
Available for sales of common shares under the facility			$ 50,000,000
Lincoln Park [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Ownership percentage			4.99%
Lincoln Park [Member] | Common Stock [Member] | Maximum [Member]
Class Of Stock [Line Items]
Purchase shares | shares			1,200
Lincoln Park [Member] | Purchase Agreement [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Price per share | $ / shares			$ 160.5
Percentage of common shares outstanding prior to the execution of purchase agreement			19.99%
Aggregate number of common shares | shares			325,357
Lincoln Park [Member] | Regular Purchase [Member]
Class Of Stock [Line Items]
Trading volume percentage			25%
Percentage of common shares outstanding prior to the execution of purchase agreement			97%
Lincoln Park [Member] | Regular Purchase [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Regular purchase, description			The Fully Adjusted Regular Purchase Share Limit may be increased as follows: to up to 2,000 shares if the closing price is not below $125.00, and up to 3,000 shares if the closing price is not below $250.00
Committed obligation amount			$ 500,000
Lincoln Park [Member] | Regular Purchase [Member] | Common Stock [Member] | Maximum [Member]
Class Of Stock [Line Items]
Purchase shares | shares				1,200
[1] Amounts have been retroactively restated to reflect the 1-for-25 reverse stock split effected on January 12, 2024 (see Note 1. Organization and Basis of Presentation of the accompanying notes to the consolidated financial statements).

Preferred Stock and Stockhold_4

Preferred Stock and Stockholders' Equity - Summary of Option Activity Under the Company's Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Equity [Abstract]
Number of Option Outstanding,Beginning balance	349,495
Number of Option Outstanding,Granted	151,589
Number of Option Outstanding,Exercised	(3,590)
Number of Option Outstanding, Cancelled or forfeited	(16,619)
Number of Option Outstanding,Ending balance	480,875	349,495
Number of Option Exercisable	292,803
Weighted Average Exercise Price,Beginning balance	$ 68.23
Weighted Average Exercise Price,Granted	13.01
Weighted average exercise price,Exercised	13
Weighted average exercise price, Cancelled or forfeited	55.7
Weighted Average Exercise Price,Ending balance	51.67	$ 68.23
Weighted Average Exercise Price,Exercisable	$ 57.64
Weighted- Average Remaining Contractual Term,Beginning balance	7 years 3 months 18 days	7 years 4 months 24 days
Weighted- Average Remaining Contractual Term,Granted	9 years 1 month 6 days
Weighted- Average Remaining Contractual Term, Cancelled or forfeited	6 years 7 months 6 days
Weighted- Average Remaining Contractual Term, Ending balance	7 years 3 months 18 days	7 years 4 months 24 days
Weighted- Average Remaining Contractual Term,Exercisable	6 years 3 months 18 days
Aggregate Intrinsic Value,Beginning balance	$ 0
Aggregate Intrinsic Value,Ending balance	0	$ 0
Aggregate Intrinsic Value,Exercisable	$ 0

Preferred Stock and Stockhold_5

Preferred Stock and Stockholders' Equity - Schedule of assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock option grants (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years 2 months 12 days
Expected dividend yield	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	3.60%	1.70%
Expected volatility	84%	82%
Expected term (in years)	5 years 3 months 18 days	5 years 2 months 12 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	4.40%	4.10%
Expected volatility	85%	86%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Preferred Stock and Stockhold_6

Preferred Stock and Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Stock options issued and outstanding	480,875	349,495
Common stock warrants issued and outstanding	$ 768,592
Placement agent warrants issued and outstanding	$ 53,799
Unvested sponsor shares	12,000
Authorized for future stock awards or option grants	96,449
Authorized for future issuances under the ESPP	59,144
Total	1,711,457
Public Warrants Issued and Outstanding
Class Of Stock [Line Items]
Class of Warrant or Right, Outstanding	233,332	233,332
Private Placement Warrants Issued and Outstanding
Class Of Stock [Line Items]
Class of Warrant or Right, Outstanding	7,266	7,266
Common Stock [Member]
Class Of Stock [Line Items]
Stock options issued and outstanding	480,875

Earn-Out Shares - Additional In

Earn-Out Shares - Additional Information (Detail) - USD ($)			12 Months Ended
	Aug. 25, 2023	Aug. 25, 2021	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Consecutive trading days required for entitlement of common stock			30 days
Trading Days Required For Entitlement Of Common Stock1			20 days
Common stock price per share			$ 0.0001	$ 0.0001
Fair Value Adjustment Of Earn-Out liability			$ 6,000	$ 12,124,000
Decrease in the warrant liability			$ 0	$ (638,000)
Common stock, shares issued			2,994,679	1,679,602
Earn-Out Shares [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Fair value of earn-out shares				$ 0.01
Fair value of option holder Earn-out Shares		$ 7,900,000
Fair Value Adjustment Of Earn-Out liability	$ 6,000		$ 0	$ 12,100,000
Share based compensation				$ 300,000
Share based compensation service period		4 months 9 days
Unrecognized compensation expense			$ 0
Earn-Out Shares [Member] | Stockholders [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Common stock, shares issued			182,422	17,512
Earn-Out Shares [Member] | Effector Therapeutics Inc [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Business acquisition, equity interest issued or issuable, number of shares			200,000
Common stock price per share			$ 500

Earn-Out Shares - Summary of Es

Earn-Out Shares - Summary of Estimated Fair Value of Earn-Out Shares (Detail) - Earn-Out Shares [Member]	Dec. 31, 2022 yr shares
Stock price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input | shares	10.69
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.15
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.048
Forecast period (in years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input | yr	0.6
Cost of equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.20

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Aug. 31, 2021	Jul. 31, 2021
License Agreement Disclosure [Line Items]
Research and development capitalization	$ 22,919,000	$ 23,313,000
Regents of the University of California [Member]
License Agreement Disclosure [Line Items]
Payable in connection with the closing of the merger agreement			$ 1,000,000
Research and development capitalization	$ 15,000	$ 15,000
Regents of the University of California [Member] | Amendment to the License Agreement [Member]
License Agreement Disclosure [Line Items]
Payable in connection with the closing of the merger agreement				$ 1,000,000
Regents of the University of California [Member] | Amendment to the License Agreement [Member] | Certain Clinical and Regulatory Milestones [Member]
License Agreement Disclosure [Line Items]
Remaining milestone payments payable				$ 375,000

Research Collaboration and Li_2

Research Collaboration and License Agreement - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2023	Dec. 31, 2022
Research Collaboration And License Agreement [Line Items]
Performance obligation transaction price		$ 27,000
Revenue from contract with customer excluding assessed tax		0	$ 3,553
Based on License [Member]
Research Collaboration And License Agreement [Line Items]
Performance obligation transaction price		25,600
Based on Research Activities [Member]
Research Collaboration And License Agreement [Line Items]
Performance obligation transaction price		1,400
Early Development and Regulatory Milestones [Member]
Research Collaboration And License Agreement [Line Items]
Upfront of milestones payment		80,000
Non Early Stage Development Milestones [Member] | Non Exercise of Co-Funding And Co-Promotion Option [Member]
Research Collaboration And License Agreement [Line Items]
Upfront of milestones payment		165,000
Non Early Stage Development Milestones [Member] | Exercise of Co-Funding And Co-Promotion Option [Member]
Research Collaboration And License Agreement [Line Items]
Upfront of milestones payment		70,000
Specified Sales Based Milestones [Member]
Research Collaboration And License Agreement [Line Items]
Upfront of milestones payment		235,000
Pfizer [Member]
Research Collaboration And License Agreement [Line Items]
Upfront payment received	$ 15,000
Research and Development Agreement [Member]
Research Collaboration And License Agreement [Line Items]
Revenue from contract with customer excluding assessed tax		$ 0	$ 0

DARPA Grant Revenue - Additiona

DARPA Grant Revenue - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Revenue Reconciling Item [Line Items]
Allowable costs of reimbursable	$ 5,000
Maximum
Segment Reporting Revenue Reconciling Item [Line Items]
Reimbursement amount	$ 5,000
Cooperative Agreement [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues		$ 0	$ 3,600
Reimbursable for allowable costs			$ 5,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Operating lease, payments	$ 0.1	$ 0.1
Solana Beach, California
Lessee, Lease, Description [Line Items]
Operating lease, cost	$ 0.1	$ 0.1
Lease term			3 years

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
Operating lease right-of-use assets	$ 53	$ 111
Total right-of-use assets	53	111
Liabilities
Operating lease liabilities, current	60	60
Operating lease liabilities, non-current	0	60
Total operating lease liabilities	$ 60	$ 120

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Future Minimum Rental Payments for Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
2024	$ 62
Total remaining lease payments	62
Less: imputed interest	(2)
Total operating lease liabilities	60	$ 120
Less: current portion	(60)
Operating lease liabilities, non-current	$ 0	$ 60
Weighted-average remaining lease term (in years)	9 months 29 days
Weighted-average discount rate	8%

Employee Benefits (Additional I

Employee Benefits (Additional Information) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($)
Retirement Benefits [Abstract]
Defined Contribution Plan, Cost	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 0	$ 0
Valuation allowance	64,651	56,666
Net operating loss	(33,844)	(32,403)
Research and development credits	100
Deferred tax assets for net operating losses	600
Research credits	100
Unrecognized tax benefits income tax penalties	0	50,000
Unrecognized tax benefits income interest	40,000	62,000
Unrecognized Tax Benefits	9,817	8,860	$ 8,235
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss		$ 122,400
Net operating loss carryforwards	200,900
Research and development credits	11,400
Orphan drug tax credit, carryforwards	2,200
California [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss	1,800
Net operating loss carryforwards	93,800
Research and development credits	4,800
Unrecognized Tax Benefits	$ 8,300

Income Taxes - Schedule of Net

Income Taxes - Schedule of Net Deferred Tax Assets Components (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets, Net [Abstract]
Net operating loss carryforwards	$ 46,365	$ 42,243
Intangibles	174	189
Research and development capitalization	6,525	3,839
Accrued compensation	2,070	2,282
Credits	9,395	8,013
Fixed assets	21	10
Other, net	99	88
Right-of-use liability	13	25
Deferred tax assets	64,662	56,689
Deferred tax liabilities:
Right-of-use asset	(11)	(23)
Deferred tax liabilities	(11)	(23)
Net deferred tax assets	64,651	56,666
Valuation allowance	(64,651)	(56,666)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ (7,520)	$ (4,760)
State income taxes, net of federal benefits	0	(2,076)
Change in valuation allowance	7,990	7,726
Uncertain tax positions	793	586
Gain on change in fair value of earn-out liability	(1)	(2,546)
Permanent differences and other	974	281
Transaction Costs	6	244
Capitalized R&D	0	3,381
LWAC net operating loss	(259)	(1,370)
Credits	(1,983)	(1,466)
Income tax expense (benefit)	$ 0	$ 0

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, Beginning balance	$ 8,860	$ 8,235
Additions/(reductions) for tax positions - prior year	117	0
Increase related to current year positions	840	625
Unrecognized tax benefits, Ending balance	$ 9,817	$ 8,860

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 29, 2024	Dec. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Number Of Common Shares Issued		2,994,679	1,679,602
Warrants and rights outstanding, term		5 years
Issuance of common stock, net of issuance costs		$ 6,929	$ 3,958
January 2024 Pre-Funded Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Warrant exercised	497,834
January 2024 Common Stock Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Warrants and rights outstanding, term	3 years 6 months
January 2024 Placement Agent Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Warrants and rights outstanding, term	3 years 6 months
Registered Direct Offering [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Common Shares Issued	338,000
Gross Proceeds from January 2024 Registered Direct Offering	$ 15,000
Issuance of common stock, net of issuance costs	13,600
Commissions and Other Transaction Costs	$ 1,400
Registered Direct Offering [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Common Shares Issued, Per Share	$ 10.075
Registered Direct Offering [Member] | January 2024 Pre-Funded Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number Of Common Shares Issued	1,150,834
Registered Direct Offering [Member] | January 2024 Pre-Funded Warrants [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Common Shares Issued, Per Share	$ 10.074
Exercise Price of Warrants	$ 0.001
Purchase of Common Stock in issuance of Warrants	1,488,834
Registered Direct Offering [Member] | January 2024 Common Stock Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Warrants Maturity Date	Jul. 29, 2027
Registered Direct Offering [Member] | January 2024 Common Stock Warrants [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Exercise Price of Warrants	$ 9.95
Registered Direct Offering [Member] | January 2024 Placement Agent Warrants [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Warrants Maturity Date	Jul. 29, 2027
Registered Direct Offering [Member] | January 2024 Placement Agent Warrants [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Exercise Price of Warrants	$ 12.5938
Purchase of Common Stock in issuance of Warrants	104,218
H.C. Wainwright & Co., LLC [Member] | Registered Direct Offering [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Cash Fee Percentage	7%
Management Fee Percentage	1%
Payment to Private Placement Agent	$ 25,000
Legal Counsel Fees and Expenses	50,000
Clearing Fees Related to Placement Agent	$ 15,950
H.C. Wainwright & Co., LLC [Member] | Registered Direct Offering [Member] | January 2024 Placement Agent Warrants [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Percentage of Warrants Issued Equal to Common Stock	7%