ContraFect (CFRXQ) 10-Q 14 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Nov. 10, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Entity Interactive Data Current	Yes
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	CFRX
Entity Registrant Name	ContraFect Corporation
Entity Central Index Key	0001478069
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Shell Company	false
Entity File Number	001-36577
Entity Tax Identification Number	39-2072586
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	28 Wells Avenue
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	Yonkers
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10701
City Area Code	914
Local Phone Number	207-2300
Entity Common Stock, Shares Outstanding		10,704,803
Document Transition Report	false
Document Quarterly Report	true

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 5,413	$ 8,907
Marketable securities		4,775
Prepaid expenses	1,095	1,382
Other current assets	12	2,642
Total current assets	6,520	17,706
Property and equipment, net	511	627
Operating lease right-of-use assets	1,989	2,241
Other assets	105	105
Total assets	9,125	20,679
Current liabilities:
Accounts payable	8,179	13,671
Accrued and other current liabilities	3,464	6,498
Current portion of lease liabilities	680	671
Total current liabilities	12,323	20,840
Warrant liabilities	652	9,299
Long-term portion of lease liabilities	1,873	2,210
Other liabilities	38	182
Total liabilities	14,886	32,531
Commitments and contingencies
Stockholders' deficit:
Preferred stock, $0.0001 par value, 25,000,000 shares authorized and none issued and outstanding at September 30, 2023 and December 31, 2022
Common stock, $0.0001 par value, 125,000,000 shares authorized, 10,704,803 and 594,983 shares outstanding at September 30, 2023 and December 31, 2022	1	1
Additional paid-in capital	334,243	313,884
Accumulated other comprehensive loss		(32)
Accumulated deficit	(340,003)	(325,705)
Total stockholders' deficit	(5,759)	(11,852)
Total liabilities and stockholders' deficit	$ 9,125	$ 20,679

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares outstanding	0	0
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares outstanding	10,704,803	594,983

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses:
Research and development	$ 3,869	$ 10,814	$ 14,034	$ 40,299
General and administrative	2,808	3,366	9,476	9,886
Restructuring		7,719		7,719
Total operating expenses	6,677	21,899	23,510	57,904
Loss from operations	(6,677)	(21,899)	(23,510)	(57,904)
Other income (expense):
Interest income, net	109	9	310	64
Other expense			(96)
Change in fair value of warrant liabilities	1,209	4,823	8,998	2,527
Total other income	1,318	4,832	9,212	2,591
Net loss	$ (5,359)	$ (17,067)	$ (14,298)	$ (55,313)
Per share information:
Basic net loss per share	$ (0.5)	$ (34.72)	$ (2.57)	$ (112.51)
Weighted average shares outstanding basic	10,704,803	491,626	5,559,348	491,626
Diluted net loss per share	$ (0.5)	$ (34.72)	$ (2.57)	$ (112.51)
Weighted Average Number of Shares Outstanding, Diluted	10,704,803	491,626	5,559,348	491,626

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (5,359)	$ (17,067)	$ (14,298)	$ (55,313)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities		73	32	(56)
Comprehensive loss	$ (5,359)	$ (16,994)	$ (14,266)	$ (55,369)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2021	$ 49,376	$ 1	$ 310,011	$ (84)	$ (260,552)
Beginning Balance, Shares at Dec. 31, 2021		491,626
Stock-based compensation	919		919
Unrealized gain (loss) on marketable securities	(140)			(140)
Net loss	(20,157)				(20,157)
Ending balance at Mar. 31, 2022	29,998	$ 1	310,930	(224)	(280,709)
Ending balance, Shares at Mar. 31, 2022		491,626
Beginning Balance at Dec. 31, 2021	49,376	$ 1	310,011	(84)	(260,552)
Beginning Balance, Shares at Dec. 31, 2021		491,626
Net loss	(55,313)
Ending balance at Sep. 30, 2022	(3,103)	$ 1	312,901	(140)	(315,865)
Ending balance, Shares at Sep. 30, 2022		491,626
Beginning Balance at Mar. 31, 2022	29,998	$ 1	310,930	(224)	(280,709)
Beginning Balance, Shares at Mar. 31, 2022		491,626
Stock-based compensation	965		965
Unrealized gain (loss) on marketable securities	11			11
Net loss	(18,089)				(18,089)
Ending balance at Jun. 30, 2022	12,885	$ 1	311,895	(213)	(298,798)
Ending balance, Shares at Jun. 30, 2022		491,626
Stock-based compensation	1,006		1,006
Unrealized gain (loss) on marketable securities	73			73
Net loss	(17,067)				(17,067)
Ending balance at Sep. 30, 2022	(3,103)	$ 1	312,901	(140)	(315,865)
Ending balance, Shares at Sep. 30, 2022		491,626
Beginning Balance at Dec. 31, 2022	(11,852)	$ 1	313,884	(32)	(325,705)
Beginning Balance, Shares at Dec. 31, 2022		594,983
Issuance of securities in registered offering	10,000		10,000
Issuance of securities in registered offering, Shares		128,000
Financing cost of sale of securities	(883)		(883)
Issuance of common stock for exercise of pre-funded warrants	5		5
Issuance of common stock for exercise of pre-funded warrants, Shares		842,937
Stock-based compensation	932		932
Unrealized gain (loss) on marketable securities	32			32
Net loss	(1,371)				(1,371)
Ending balance at Mar. 31, 2023	(3,137)	$ 1	323,938		(327,076)
Ending balance, Shares at Mar. 31, 2023		1,565,920
Beginning Balance at Dec. 31, 2022	(11,852)	$ 1	313,884	$ (32)	(325,705)
Beginning Balance, Shares at Dec. 31, 2022		594,983
Net loss	(14,298)
Ending balance at Sep. 30, 2023	(5,759)	$ 1	334,243		(340,003)
Ending balance, Shares at Sep. 30, 2023		10,704,803
Beginning Balance at Mar. 31, 2023	(3,137)	$ 1	323,938		(327,076)
Beginning Balance, Shares at Mar. 31, 2023		1,565,920
Issuance of common stock for exercise of pre-funded warrants, Shares		2,104,000
Issuance of common stock for exercise of warrants	7,774		7,774
Issuance of common stock for exercise of warrants, Shares		7,034,883
Financing cost of warrant inducement and exercise	(414)		(414)
Reversal of warrant liability due to exercise of warrants	1,442		1,442
Stock-based compensation	795		795
Net loss	(7,568)				(7,568)
Ending balance at Jun. 30, 2023	(1,108)	$ 1	333,535		(334,644)
Ending balance, Shares at Jun. 30, 2023		10,704,803
Stock-based compensation	708		708
Net loss	(5,359)				(5,359)
Ending balance at Sep. 30, 2023	$ (5,759)	$ 1	$ 334,243		$ (340,003)
Ending balance, Shares at Sep. 30, 2023		10,704,803

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Cash flows from operating activities
Net loss			$ (14,298)	$ (55,313)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation			120	115
Stock-based compensation expense			2,436	2,890
Issuance costs allocated to warrants			96
Change in fair value of warrant liabilities	$ (1,209)	$ (4,823)	(8,998)	(2,527)
Net amortization of premium on marketable securities			57	556
Changes in operating assets and liabilities:
Decrease (increase) in prepaid expenses and other current and non-current assets			2,857	6,709
(Decrease) increase in accounts payable, accrued and other liabilities			(7,888)	11,564
Net cash used in operating activities			(25,618)	(36,006)
Cash flows from investing activities
Proceeds from maturities of marketable securities			4,750	21,531
Sales of marketable securities				2,504
Purchases of property and equipment			(20)	(19)
Net cash provided by investing activities			4,730	24,016
Cash flows from financing activities
Proceeds from Issuance of Common Stock			19,567
Payment of financing costs of securities sold			(1,393)
Repayments of insurance premium financing			(785)
Proceeds from the exercise of pre-funded warrants			5
Net cash provided by financing activities			17,394
Net increase (decrease) in cash and cash equivalents			(3,494)	(11,990)
Cash and cash equivalents at beginning of period			8,907	16,654	$ 16,654
Cash and cash equivalents at end of period	$ 5,413	$ 4,664	5,413	$ 4,664	$ 8,907
Supplemental schedule of cash flow information
Issuance of warrants to purchase common stock			1,793
Cash paid for interest			21
Supplemental schedule of non-cash financing activities
Insurance premium financing			$ 900

Organization and Description of

Organization and Description of Business	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Organization and Description of Business	1. Organization and Description of Business Organization and Business ContraFect Corporation (the “Company”) is a clinical-stage biotechnology company focused on the discovery and development of direct lytic agents (“DLAs”), including lysins and amurin peptides, as new medical modalities for the treatment of life-threatening, antibiotic-resistant infections. The Company intends to address antibiotic-resistant infections using product candidates from our lysin and amurin peptide platforms. DLAs are fundamentally different than antibiotics and offer a potential paradigm shift in the treatment of antibiotic-resistant infections. The Company’s most advanced product candidate is exebacase, a lysin which targets S. aureus , including methicillin-resistant strains, which causes serious infections such as bacteremia, pneumonia and osteomyelitis. S. aureus is also a frequent source of biofilm-dependent infections of heart valves (endocarditis), prosthetic joints, indwelling devices and catheters. These infections result in significant morbidity and mortality despite current antibiotic therapy. Exebacase was being studied in a pivotal Phase 3 superiority study (the “DISRUPT study”) to evaluate the safety, tolerability, efficacy and pharmacokinetics of intravenous (“IV”) exebacase when used in addition to background standard of care antibiotic therapy for the treatment of S. aureus bacteremia, including right-sided endocarditis in adolescent and adult patients. On July 7, 2022, the Data Safety Monitoring Board (“DSMB”) conducted an interim futility analysis and recommended that the DISRUPT study be stopped because the conditional power of the study was below the pre-specified threshold for futility. Based on the DSMB’s recommendation, patient enrollment in the Phase 3 trial was stopped (“Trial Closure”). The Company continued to monitor all already enrolled patients and all patients completed their follow-up visits. The Company expects to complete all clinical study reports as required by the U.S. Food and Drug Administration (“FDA”). On July 29, 2022, the Company initiated a restructuring plan resulting in a reduction in workforce. The restructuring plan was designed to reduce costs and align resources with the Company’s anticipated product development milestones for exebacase and CF-370 and to help preserve the value of the Company’s drug discovery operations. The restructuring reduced the Company’s workforce from 43 full-time employees as of June 30, 2022 to 27 full-time employees as of August 15, 2022, when the reduction was completed. The Company recognized a restructuring charge of $ 7.7 million, including $ 1.6 million related to employee termination costs and other related expenses from the workforce reduction and $ 6.1 million from the write-off of prepaid manufacturing costs following the suspension of IV exebacase related activities. The Company has incurred recurring losses since inception as a research and development organization and has an accumulated deficit of $ 340.0 million as of September 30, 2023. For the nine months ended September 30, 2023, the Company used $ 25.6 million of cash in operations. The Company has relied on its ability to fund its operations through public and private debt and equity financings, and, to a lesser extent, grant funding and government contracts. The Company expects operating losses and negative cash flows to continue at significant levels in the future to the extent it continues to advance its programs. As of September 30, 2023, the Company had $ 5.4 million in cash, cash equivalents and marketable securities, which, without additional funding, the Company believes will not be sufficient to meet its obligations soon after the date of issuance of these consolidated financial statements. The Company's future viability is dependent on its ability to fund its operations through public or private debt and equity financings, but there can be no assurances that such financing will continue to be available to the Company on satisfactory terms, or at all, particularly in light of the suspension from trading of the Company's common stock on the Nasdaq Capital Market. As such, management has not considered the potential for future capital raises in its assessment of the Company’s ability to meet its obligations for the next twelve months, and substantial doubt exists about the Company’s ability to continue as a going concern for twelve months from the date the financial statements were issued. If the Company is unable to obtain funding in the near-term, the Company would be forced to delay, further reduce its workforce or reduce or eliminate its research and development programs, which could adversely affect its business prospects, or the Company may be unable to continue operations or continue as a going concern. The Company has sought a strategic partnership or collaboration with one or more parties and has also sought other financial and strategic alternatives. To date, the Company has continued research and development activities while managing its cash position. However, the Company requires additional resources in order to continue as a going concern. The Company can provide no assurance that it will be successful in obtaining additional resources to improve its financial condition. If the Company is unable to obtain additional resources soon, the Company’s Board of Directors is likely to determine to place the Company into bankruptcy or other dissolution proceedings. The consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates continuity of operations, the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. On March 22, 2021, the Company completed an underwritten public offering under the Company’s registration statement on Form S-3 (Reg. No. 333-246359) (the “Form-S-3”). The Form S-3 was declared effective by the SEC on August 31, 2020 and allows the Company to offer and sell from time-to-time up to $ 150.0 million of common stock, preferred stock, debt securities, warrants or units comprised of any combination of these securities. The Company issued 143,750 shares of its common stock, including shares sold pursuant to the fully exercised overallotment option granted to the underwriters in connection with the offering, at a public offering price of $ 400.00 per share, resulting in net proceeds to the Company of $ 53.8 million after underwriting discounts and commissions and offering expenses payable by the Company. On December 15, 2022, the Company completed (i) a registered direct offering under the Form S-3 of 54,375 shares of its common stock and a pre-funded warrant to purchase 623,919 shares of common stock (the “2022 pre-funded warrant”) and (ii) a concurrent private placement in which the Company issued a Class A warrant to purchase up to an aggregate of 1,356,589 shares of common stock (the “Class A Warrant”) and a Class B warrant to purchase up to an aggregate of 678,294 shares of common stock (the “Class B Warrant”) (collectively, the “2022 Offering”). All shares of common stock, the 2022 pre-funded warrant, the Class A Warrant and the Class B Warrant were issued together to a single accredited investor purchaser for consideration equating to $ 10.32 per share of common stock (or 2022 pre-funded warrant to purchase one share of common stock, less a nominal exercise price), together with a Class A Warrant to purchase two shares of common stock and a Class B warrant to purchase one share of common stock, in the case of each of the Class A Warrant and Class B Warrant, for no additional consideration but each with an exercise price per share of $ 10.32 , for aggregate net proceeds to the Company of $ 6.1 million after placement agent fees and offering expenses payable by the Company. On March 2, 2023, the Company completed (i) a registered direct offering under the Form S-3 of 128,000 shares of its common stock and a pre-funded warrant to purchase 2,372,000 shares of common stock (the “2023 pre-funded warrant”) and (ii) a concurrent private placement in which the Company issued a warrant to purchase up to an aggregate of 5,000,000 shares of common stock (the “2023 Warrant”) (collectively, the “2023 Offering”). All securities in the 2023 Offering were issued to the same single accredited investor purchaser as in the 2022 Offering for consideration equating to $ 4.00 per share of common stock (or 2023 pre-funded warrant to purchase one share of common stock, less a nominal exercise price), together with a 2023 Warrant to purchase two shares of common stock for no additional consideration but with an exercise price per share of $ 4.00 , for aggregate net proceeds to the Company of $ 9.1 million after placement agent fees and offering expenses payable by the Company. On June 26, 2023, the Company entered into an inducement offer to exercise common stock purchase warrants (the “Inducement Agreement”) with an institutional investor (the “Holder”) to purchase up to an aggregate of 7,034,883 shares of the Company’s common stock. The Inducement Agreement provided the Holder with the opportunity to exercise all of (i) the Class A Warrant, (ii) Class B Warrant and (iii) the 2023 Warrant (collectively, the “Existing Warrants”) held by the Holder, each at a reduced exercise price from $ 4.00 to $ 1.36 per underlying share, which was equal to the most recent closing price of the Company’s common stock on The Nasdaq Capital Market prior to the execution of the Inducement Agreement. In consideration for exercising the Existing Warrants (the “Warrant Exercise”), at an exercise price equal to $ 1.36 per underlying share, the Company issued to the Holder or (i) a new unregistered Class C Common Stock Purchase Warrant (the “Class C Warrant”) to purchase up to 1,406,977 shares of common stock, at an exercise price equal to $ 1.36 per underlying share and (ii) a new unregistered Class D Common Stock Purchase Warrant (the “Class D Warrant” and together with the Class C Warrant, the “New Warrants”) to purchase up to 5,627,906 shares of common stock, at an exercise price equal to $ 1.36 per underlying share (such shares of common stock issuable upon exercise of the New Warrants, the “New Warrant Shares”). The proceeds to the Company from the Warrant Exercise were $ 9.6 million, prior to deducting fees to the financial advisor and estimated expenses. The significant changes in common stock outstanding have impacted and are expected to continue to impact the year-over-year comparability of the Company’s net loss per share calculations. All share and per share amounts have been adjusted for all periods presented to reflect a one-for-eighty reverse stock split effected on February 14, 2023.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial information as of September 30, 2023 and for the three and nine months ended September 30, 2023 and 2022 has been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. The consolidated balance sheet as of December 31, 2022 was derived from the Company’s audited consolidated financial statements, including all related disclosures, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 31, 2023. There have been no material changes to the complete listing of significant accounting policies as described in Note 2 thereof. In the opinion of management, the unaudited financial information as of September 30, 2023 and for the three and nine months ended September 30, 2023 and 2022 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the operating results for the full fiscal year or any future periods. Principles of Consolidation The Company has a wholly-owned subsidiary, ContraFect International Limited, in Scotland that establishes legal status for interactions with the European Economic Area. This subsidiary is dormant or is otherwise non-operative. Any inter-company accounts have been eliminated in consolidation. Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to, the results of clinical testing and trial activities of the Company’s products, the Company’s ability to obtain regulatory approval to market its products, competition from products manufactured and sold or being developed by other companies, the price of, and demand for, the Company’s products, the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products, the Company’s ability to raise capital and the effects of COVID-19 and the recent failure of certain financial institutions, on the Company’s business, operations and financial performance and position. The Company currently relies on a single manufacturer of drug substance for each of its product candidates and two manufacturers of drug product, one located in the United States and one in Western Europe, and there are no long-term supply agreements in place. A sustained disruption in the operations of any of these manufacturers, or in the event the Company would need to change to a new supplier, could result in a significant delay in the ability of the Company to complete any associated activities. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to stock-based compensation, warrant valuation, research and development accruals and prepaid expenses and realization of net deferred income tax assets. The Company’s actual results may differ from these estimates under different assumptions or conditions. Concentrations of Credit Risk Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company’s accounts at Silicon Valley Bank have not experienced any credit losses and the Company does not believe it has material exposure to any significant credit risk on these funds. The Company maintains the majority of its cash, cash equivalents and marketable securities at other financial institutions. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. Cash and Cash Equivalents The Company considers all highly liquid investments with maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits, marketable securities with maturities of three months or less at purchase, and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value. Marketable Securities Marketable securities consist of investments in corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities . The Company classifies marketable securities available to fund current operations as current assets on its consolidated balance sheets. Marketable securities are classified as long-term assets on the consolidated balance sheets if (i) the Company has the intent and ability to hold the investments for a period of at least one year and (ii) the contractual maturity date of the investments is greater than one year. Marketable securities, together with accrued interest receivable, net of any allowance for credit losses, are recorded at fair value on the consolidated balance sheet, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ deficit and a component of total comprehensive loss in the consolidated statements of comprehensive loss, until realized. The fair value of these securities is based on quoted prices for identical or similar assets. Realized gains and losses are included in interest income in the consolidated statement of operations on a specific-identification basis. There were no realized gains or losses on sales of marketable securities for the nine months ended September 30, 2023 or 2022. The Company held no marketable securities as of September 30, 2023. There were no marketable securities that had been in an unrealized loss position for more than 12 months as of December 31, 2022. The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period. Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts payable, accrued liabilities and warrant liabilities. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of judgment and therefore cannot be determined with precision. The fair value of the Company’s warrant liabilities is based upon unobservable inputs, as described further below. The Company discloses information on all assets and liabilities reported at fair value using a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company had no liabilities classified as Level 1 or Level 2. The carrying amounts reported in the accompanying financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short-term maturities. The fair value of the warrant liabilities is discussed in Note 4, “Fair Value Measurements.” Stock-based Compensation Stock-based compensation is measured and recognized as compensation expense for all stock-based payment awards made to employees, directors, and non-employees, including employee stock options. Compensation expense based on the grant date fair value is generally amortized over the requisite service period of the award on a straight-line basis. The fair value of options is calculated using the Black-Scholes option pricing model on the date of grant based on key assumptions such as stock price, risk free interest rates, expected volatility, expected term, and expected dividend yield. The Company’s estimates of these assumptions are based on historical data and judgment regarding future trends and factors . Government Contracts and Grant Agreements On March 10, 2021, the Company entered into a cost-share contract (the “BARDA Contract”) with BARDA, a division of the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response. The base period for the BARDA Contract included government funding of up to $ 9.8 million to reimburse expenses to support the conduct of the Phase 3 DISRUPT study and futility analysis. In connection with the Trial Closure, the BARDA Contract was modified to provide for up to $ 6.6 million in funding to support a futility outcome root-cause analysis and the close-out of the Phase 3 DISRUPT study of exebacase. The BARDA Contract ended on July 31, 2023. The Company recognizes a receivable in other current assets with a related reduction in its research and development expenses when the actual reimbursable costs have been incurred and the Company has complied with the conditions of the applicable government contract or grant agreement and the amounts will be received. The Company recognized a reduction to its research and development expense in the amount of less than $ 0.1 million and $ 0.9 million for the three months ended September 30, 2023 and 2022, and $ 3.2 million and $ 5.2 million for the nine months ended September 30, 2023 and 2022, respectively. The receivable for government contracts and grant agreements as of September 30, 2023 and December 31, 2022 was less than $ 0.1 million and $ 2.6 million, respectively. The Company has $ 2.0 million of committed grant agreement funding remaining as of September 30, 2023. Restructuring The Company has made estimates and judgments regarding the amount and timing of its restructuring expense and liability, including current and future period termination benefits and other costs to be incurred when related actions take place. Actual results may differ from these estimates. Restructuring charges are reflected in the Company’s consolidated statements of operations. Net Loss Per Share Basic net loss per share applicable to common stockholders is calculated by dividing net loss applicable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share applicable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the dilutive net loss per share applicable to common stockholders’ calculation, stock options and warrants are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. Recently Adopted Accounting Pronouncements Credit Losses On January 1, 2023, the Company adopted Accounting Standards Update No. 2016-13, Financial Instruments-Credit Losses (ASU 2016-13). ASU 2016-13 amended the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the “incurred loss” model with an “expected loss” model. Accordingly, these financial assets will be presented at the net amount expected to be collected. This new standard also requires that credit losses related to available-for-sale debt securities be recorded through an allowance for such losses rather than reducing the carrying amount under the current, other-than-temporary-impairment model. The adoption of the new guidance did not affect the Company’s consolidated financial statements.

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	3. Marketable Securities The Company held no marketable securities as of September 30, 2023. Marketable securities at December 31, 2022 consisted of the following (in thousands): Marketable Securities Amortized Cost Unrealized Unrealized Fair Value Current: Corporate debt $ 4,807 $ — $ ( 32 ) $ 4,775 Corporate debt includes obligations issued by investment-grade corporations. At December 31, 2022, the Company held only investments that have maturities of less than one year .

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 (in thousands): Fair Value Measurement as of September 30, 2023 Quoted Prices Significant Significant Cash equivalents $ 4,086 $ — $ — Marketable securities — — — Warrant liabilities — — 652 Total $ 4,086 $ — $ 652 Fair Value Measurement as of December 31, 2022 Quoted Prices Significant Significant Cash equivalents $ 7,596 $ — $ — Marketable securities 4,775 — — Warrant liabilities — — 9,299 Total $ 12,371 $ — $ 9,299 The Company issued warrants to the purchasers of its 2020 Offering (the “2020 Warrants”). The Company determined that these warrants should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The 2020 Warrants were re-measured at each subsequent reporting period and changes in fair value have been recognized in the consolidated statement of operations. The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability as of December 31, 2022. On May 27, 2023, the 2020 Warrants expired in accordance with their terms and are no longer exercisable. As of Expected volatility 80.2 % Remaining contractual term (in years) 0.42 Risk-free interest rate 4.76 % Expected dividend yield — % The Company issued the Class A Warrant and Class B Warrant to the purchaser of its 2022 Offering (together, the “2022 Warrants”). The Company determined that these warrants should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). On June 26, 2023, the Class A Warrant and Class B Warrant, together with the 2023 Warrant, were exercised in full pursuant to the Inducement Agreement. The 2022 Warrants were re-measured at each subsequent reporting period and on June 26, 2023 and the changes in fair value have been recognized in the consolidated statement of operations. The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: Class A Warrants Class B Warrants As of As of As of As of Expected volatility 135.5 % 99.8 % 129.5 % 140.3 % Remaining contractual term (in years) 4.63 5.08 0.13 0.58 Risk-free interest rate 4.13 % 3.99 % 5.32 % 4.76 % Expected dividend yield — % — % —% —% On June 27, 2023, the Company issued the Class C Warrant pursuant to the Inducement Agreement and determined that this warrant should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The Class C Warrant was re-measured at each subsequent reporting period and the changes in fair value have been recognized in the consolidated statement of operations. The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: As of At Issuance Expected volatility 130.0 % 129.1 % Remaining contractual term (in years) 5.17 5.25 Risk-free interest rate 4.60 % 4.02 % Expected dividend yield — % — % Warrant liabilities The following tables present a reconciliation of the Company’s financial liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2023 and 2022 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Balance at beginning of period $ 1,861 $ 4,826 $ 9,299 $ 2,530 Issuance of Class C Warrant — — 1,793 — (Decrease) increase in fair value (1) ( 1,209 ) ( 4,823 ) ( 8,998 ) ( 2,527 ) Exercise of underlying warrants (2) — — ( 1,442 ) — Balance at end of period $ 652 $ 3 $ 652 $ 3 (1) The change in fair values of the warrant liabilities is recorded in other income in the consolidated statement of operations. (2) The remaining fair value of the warrant liabilities at the time of exercise was transferred into additional paid-in capital in the consolidated balance sheet. The key inputs into the Black-Scholes option pricing model are the per share value and the expected volatility of the Company’s common stock. Significant changes in these inputs will directly increase or decrease the estimated fair value of the Company’s warrant liability.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Accrued and Other Current Liabilities	5. Accrued and Other Current Liabilities Accrued and other current liabilities consist of the following as of September 30, 2023 and December 31, 2022 (in thousands): September 30, December 31, Accrued compensation costs $ 1,583 $ 1,676 Accrued professional fees 928 970 Accrued research and development service fees 723 3,443 Accrued insurance and facilities operation expenses 207 252 Other accrued expenses 23 157 Total accrued and other current liabilities $ 3,464 $ 6,498 In February 2023, the Company entered into a financing agreement for $ 0.9 million for a portion of the Company’s annual directors and officers insurance premiums. The balance is due in monthly installments over eight months with an annual interest rate of 6.25 %. The remaining balance was $ 0.1 million as of September 30, 2023 and is included in accounts payable on the consolidated balance sheet.

Net Loss Per Share of Common St

Net Loss Per Share of Common Stock	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Loss Per Share of Common Stock	6. Net Loss Per Share of Common Stock Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss. Basic loss per share is computed by dividing net loss available to common stockholders by the weighted-average number of common shares outstanding, including the weighted average effect of the pre-funded warrants the Company issued in connection with the 2022 and 2023 Offerings, the exercise of which requires nominal consideration for the delivery of shares of common stock. As such, the Company has considered the 574,937 common shares underlying the pre-funded warrants that were unexercised as of December 31, 2022 to be outstanding beginning on January 1, 2023 for the purposes of calculating basic EPS. There were no pre-funded warrants outstanding as of September 30, 2023. The following table sets forth the computation of basic and diluted net loss per share for common stockholders (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Net loss $ ( 5,359 ) $ ( 17,067 ) $ ( 14,298 ) $ ( 55,313 ) Weighted average shares of common stock outstanding 10,704,803 491,626 5,559,348 491,626 Net loss per share of common stock—basic and diluted $ ( 0.50 ) $ ( 34.72 ) $ ( 2.57 ) $ ( 112.51 ) The following potentially dilutive securities outstanding at September 30, 2023 and 2022 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive: September 30, 2023 2022 Options to purchase common stock 79,582 56,442 Warrants to purchase common stock 7,034,883 116,569 Total 7,114,465 173,011

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Operating Leases In December 2010, the Company entered into a non-cancellable operating lease for office space and laboratory facilities in Yonkers, New York expiring in December 2025 . In December 2011, the Company entered into an amendment which extended the term of the lease through December 2027 (the “Third Floor Lease”). The lease provides for the option to renew for two additional five-year terms. The premises were occupied in June 2011. Monthly rent payments began the date the office and laboratory facilities were ready for occupancy. In January 2012, the Company entered into a non-cancellable operating lease for additional office space and laboratory facilities in the same building in Yonkers, New York expiring in December 2027 (the “Fourth Floor Lease”). The Fourth Floor Lease provides for an option to renew for two additional five-year terms. Effective August 1, 2017, the Company relinquished 10,912 square feet of space under the Fourth Floor Lease and was relieved of its obligations related to such space. The balance sheet classification of the Company’s lease liabilities was as follows (in thousands): Description September 30, December 31, Operating lease liabilities: Current portion of lease liabilities $ 680 $ 671 Long-term portion of lease liabilities $ 1,873 $ 2,210 The Company adopted Topic 842 in accounting for its lease liabilities as of January 1, 2019. Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company used a discount rate of 9.93 %, which was an estimate of its incremental borrowing rate based on the information available at the adoption date. The leases are renewable at the end of the lease term at the Company’s option. For the purposes of determining the remaining lease term in contemplation of available extensions, the Company did not consider either renewal to be probable and therefore the remaining lease term used to determine the operating lease liability was 9.0 years at the adoption date. As of September 30, 2023, the maturities of our operating lease liabilities were as follows (in thousands): Amount October 1, 2023—December 31, 2023 $ 177 Year ending December 31: 2024 721 2025 736 2026 750 2027 702 Total lease payments 3,086 Less: Present value adjustment ( 533 ) Operating lease liabilities $ 2,553 Lease costs under the terms of the Company’s leases for the three and nine months ended September 30, 2023 and 2022 were as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Operating lease cost (1) $ 151 $ 154 $ 451 $ 460 Variable lease costs (2) 47 66 98 147 Total lease cost $ 198 $ 220 $ 549 $ 607 (1) Operating lease payments included in the measurement of the Company’s lease liabilities are comprised of fixed payments according to the terms of the Company’s leases. (2) Variable lease payments consist of the Company’s utility costs billed by and paid to its landlord. Variable lease payments are presented as operating expenses in the Company’s Consolidated Statement of Operations in the same line item as expense arising from fixed lease payments and in net cash used in operating activities in the Company’s Statement of Cash Flows. Rockefeller University License Agreements The Company has entered into the following license agreements with The Rockefeller University: • On July 12, 2011, the Company entered into a license agreement for the worldwide, exclusive right to a patent covering the composition of matter for the lysin PlySS2 for the treatment and prevention of diseases caused by gram-positive bacteria (the “CF-301 License”). The Company rebranded PlySS2 as CF-301 and subsequently, exebacase. The license gives the Company the right to exclusively develop, make, have made, use, import, lease, sell and offer for sale products that would otherwise infringe a claim of this patent application or patent. • On June 1, 2011, the Company entered into a license agreement for the exclusive rights to The Rockefeller University’s interest in a joint patent application covering the method of delivering antibodies through the cell wall of gram-positive bacteria to the periplasmic space. This intellectual property was developed as a result of the sponsored research agreement between the Company and The Rockefeller University and was jointly discovered and filed by the two parties. • On September 23, 2010, the Company entered into a license agreement for the worldwide, exclusive right to develop, make, have made, use, import, lease, sell, and offer for sale products that would otherwise infringe a claim of the suite of patents and patent applications covering the composition of matter for eight individual lysin molecules for the treatment and prevention of diseases caused by gram-positive bacteria. The lysins in this suite have activity against Group B Streptococci , Staphylococcus aureus, Streptococcus pneumonia, Bacillus anthracis, Enterococcus faecalis and Enterococcus faecium . In consideration for the licenses, the Company paid Rockefeller license initiation fees in cash and stock. The Company is currently required to pay $ 0.2 million each year until the licenses terminate. Depending on the success of its programs, the Company may also incur regulatory milestone payments up to a total of $ 5.0 million and royalties of up to 5 % on net sales from products to Rockefeller. The Company is allowed to grant sublicenses to third parties without prior approval, subject to certain conditions and the payment of a certain percentage of all payments we receive from sublicensees. There were no milestone, royalty or sublicense payments made during the three or nine months ended September 30, 2023 or 2022. The Company has made total milestone payments under the CF-301 License of $ 0.8 million as of September 30, 2023. Each license agreement terminates upon the later of (i) the expiration or abandonment of the last licensed patent under the license agreement to expire or become abandoned, or (ii) 10 years after the first commercial sale of the first licensed product. The Rockefeller University may terminate any license agreement in the event of a breach of such agreement by the Company or if the Company challenges the validity or enforceability of the underlying patent rights. The Company may terminate any license agreement at any time on 60 days’ notice. Legal Contingencies From time to time, the Company may be involved in disputes and legal proceedings in the ordinary course of its business. These proceedings may include allegations of infringement of intellectual property, employment or other matters. The Company records a liability in its financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in the Company’s financial statements. The Company currently has no legal proceedings ongoing that management estimates could have a material effect on the Company’s financial statements.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Restructuring	8. Restructuring On July 29, 2022, the Company initiated a restructuring plan resulting in a reduction in workforce. The restructuring plan was designed to reduce costs and align resources with the Company’s anticipated product development milestones for exebacase and CF-370 and to help preserve the value of the Company’s drug discovery operations. The restructuring reduced the Company’s workforce from 43 full-time employees as of June 30, 2022 to 27 full-time employees as of August 15, 2022, when the reduction was completed. The Company recognized a restructuring charge of $ 7.7 million, including $ 1.6 million related to employee termination costs, including severance, health benefits and other related expenses from the workforce reduction, and $ 6.1 million from the write-off of prepaid manufacturing costs following the suspension of IV exebacase manufacturing activities. The restructuring costs were included in accounts payable and accrued and other current liabilities. Activity for the three and nine months ended September 30, 2023 is summarized as follows (in thousands): Three Months Nine Months Balance at beginning of period $ 3,612 $ 7,143 Payments made ( 2,215 ) ( 5,746 ) Balance at end of period $ 1,397 $ 1,397 As of September 30, 2023, the Company had $ 1.4 million remaining in accounts payable and accrued and other current liabilities, which the Company expects to be paid by the end of the first quarter of 2024.

Capital Structure

Capital Structure	9 Months Ended
	Sep. 30, 2023
Federal Home Loan Banks [Abstract]
Capital Structure	9. Capital Structure On February 10, 2023, the stockholders of the Company approved a reverse stock-split of the Company’s outstanding shares of common stock at a ratio ranging from any whole number between 1-for-10 and 1-for-80 , as determined by the Board of Directors in its discretion. The Board subsequently determined to implement a reverse stock split at a ratio of 1-for-80 . The stock split became effective on February 14, 2023. Accordingly, all share and per share amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect this reverse stock split. Shares of common stock underlying outstanding stock options and other equity instruments were proportionately decreased and the respective per share value and exercise prices, if applicable, were proportionately increased in accordance with the terms of the agreements governing such securities. Common Stock As of September 30, 2023, the Company was authorized to issue 125,000,000 shares of common stock. Follow-on Offerings On May 27, 2020, the Company completed an underwritten public offering of 147,471 shares of its common stock and warrants to purchase an additional 110,603 shares of its common stock at an exercise price of $ 392.00 per share. The public offering price was $ 356.00 for one share of common stock and an accompanying warrant to purchase 0.75 shares of common stock, resulting in net proceeds to the Company of $ 48.9 million after underwriting discounts and commissions and offering expenses payable by the Company. The Company completed a concurrent private placement to Pfizer of 8,427 shares of common stock and an accompanying warrant to purchase an additional 6,320 shares of its common stock at an exercise price of $ 392.00 per share of common stock (the “Pfizer Warrant”), resulting in net proceeds to the Company of $ 3.0 million. On March 22, 2021, the Company completed an underwritten public offering of 143,750 shares of its common stock, including shares sold pursuant to the fully exercised overallotment option granted to the underwriters in connection with the offering, at a public offering price of $ 400.00 per share, resulting in net proceeds to the Company of $ 53.8 million after underwriting discounts and commissions and offering expenses payable by the Company. On December 15, 2022, the Company completed the 2022 Offering. All shares of common stock, the 2022 pre-funded warrant, the Class A Warrant and the Class B Warrant were issued together to a single accredited investor purchaser for consideration equating to $ 10.32 share of common stock (or 2022 pre-funded warrant to purchase one share of common stock, less a nominal exercise price), together with a Class A Warrant to purchase two shares of common stock and a Class B warrant to purchase one share of common stock, in the case of each of the Class A Warrant and Class B Warrant, for no additional consideration but each with an exercise price per share of $ 10.32 , for aggregate net proceeds to the Company of $ 6.1 million after placement agent fees and offering expenses payable by the Company. As of January 20, 2023, the 2022 pre-funded warrant had been fully exercised. At issuance, the 2022 Warrants were not exercisable and only became exercisable following (i) stockholder approval of (and the effectiveness of) an amendment to the Company’s certificate of incorporation that either combines outstanding shares of common stock with such combination ratio as determined by the Company’s board of directors and/or authorizes additional shares of common stock to such number as determined by the Company’s board of directors, in each case, so as to enable the issuance of the number of shares of common stock underlying the 2022 Warrants (disregarding any limitations on the exercise thereof), and (ii) the issuance of all shares of common stock issued in, or issuable pursuant to the exercise of the 2022 pre-funded warrant or 2022 Warrants issued in, the 2022 Offering as may have been required by the applicable rules and regulations of the Nasdaq Stock Market. On February 10, 2023, the stockholders of the Company approved the issuance of all shares of common stock issued in, or issuable pursuant to the exercise of the 2022 pre-funded warrant or 2022 Warrants issued in the 2022 Offering as may have been required by the applicable rules and regulations of the Nasdaq Stock Market, the approval of which, together with the approval and effectiveness of the 1-for-80 reverse stock-split effected on February 14, 2023, commenced the exercisability of the 2022 Warrants as of February 14, 2023. The resulting expiration dates of the 2022 Warrants have been reflected, where applicable, in the accompanying financial statements and notes thereto. On March 2, 2023, the exercise price of the 2022 Warrants, which are subject to an anti-dilution adjustment, were adjusted to $ 4.00 per share as a result of the 2023 Offering. On March 2, 2023, the Company completed the 2023 Offering. All securities in the 2023 Offering were issued to the same single accredited investor purchaser from the 2022 Offering for consideration equating to $ 4.00 per share of common stock (or 2023 pre-funded warrant to purchase one share of common stock, less a nominal exercise price), together with a warrant to purchase two shares of common stock for no additional consideration but with an exercise price per share of $ 4.00 , for aggregate net proceeds to the Company of $ 9.1 million after placement agent fees and offering expenses payable by the Company. As of April 17, 2023, the 2023 pre-funded warrant had been fully exercised. On June 26, 2023, the Company entered into the Inducement Agreement with the Holder to exercise common stock purchase warrants and purchase up to an aggregate of 7,034,883 shares of the Company’s common stock. The Inducement Agreement provided the Holder with the opportunity to exercise all of the Existing Warrants held by the Holder, each at a reduced exercise price from $ 4.00 to $ 1.36 per underlying share, which was equal to the most recent closing price of the Company’s common stock on The Nasdaq Capital Market prior to the execution of the Inducement Agreement. In consideration for exercising the Existing Warrants at an exercise price equal to $ 1.36 per underlying share, the Company issued to the Holder the Class C Warrant to purchase up to 1,406,977 shares of common stock, at an exercise price equal to $ 1.36 per underlying share and the Class D Warrant to purchase up to 5,627,906 shares of common stock, at an exercise price equal to $ 1.36 per underlying share. The proceeds to the Company from the Warrant Exercise were $ 9.6 million, prior to deducting fees to the financial advisor and estimated expenses. At issuance, the New Warrants were not exercisable and only become exercisable following stockholder approval of the issuance of all shares of common stock issued in, or issuable pursuant to the exercise of the New Warrants issued pursuant to the Inducement Agreement as may have been required by the applicable rules and regulations of the Nasdaq Stock Market. The Class C Warrant and the warrants issued by the Company in its 2022 and 2020 offerings of securities contained certain terms that the Company determined required classification as liabilities in accordance with ASC 815. At issuance, the Company determined the fair value of the Class C Warrant, the 2022 Warrants and the 2020 Warrants to be $ 1.8 million, $ 11.0 million and $ 31.4 million, respectively, and recorded these balances as warrant liabilities, and reducing the amount of net proceeds recorded as additional paid-in-capital. The fair value of the 2022 Warrants exceeded the proceeds received in the 2022 Offering and the excess of $ 4.0 million was expensed as other expense. The Company consummated the 2022 Offering on market terms available at the time of the transaction to provide additional funding to advance its product candidates. The fair value of these warrants is re-measured at each reporting period and changes in fair value are recognized in the consolidated statement of operations (see Note 4, “Fair Value Measurements”). Additionally, the Company allocated $ 0.1 million, $ 0.9 million and $ 2.2 million of issuance costs to the Class C Warrant, the 2022 Warrants and the 2020 Warrants, respectively, based on the proportion of the proceeds allocated to the fair value of the warrants. The allocated issuance costs were expensed as other expense. The Class D Warrant, the 2023 Warrant and the Pfizer Warrant do not contain the same provisions and therefore the Company determined that the Class D Warrant, the 2023 Warrant and the Pfizer Warrant should be classified as equity in the Company’s consolidated balance sheet. Voting The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. Dividends The holders of shares of common stock are entitled to receive dividends, if and when declared by the board of directors. As of September 30, 2023, no dividends have been declared or paid on the Company’s common stock since inception. Reserved for Future Issuance The Company has reserved for future issuance the following number of shares of common stock as of September 30, 2023 and December 31, 2022: September 30, December 31, Outstanding pre-funded warrants to purchase common stock — 574,937 Outstanding options to purchase common stock 79,582 55,565 Outstanding warrants to purchase common stock 7,034,883 2,151,451 For future issuance under the 2014 Omnibus Incentive Plan 1,099 1,317 For future issuance under the 2021 Employment Inducement Plan 12,375 12,375 7,127,939 2,795,645

Stock Warrants

Stock Warrants	9 Months Ended
	Sep. 30, 2023
Text Block [Abstract]
Stock Warrants	10. Stock Warrants As of September 30, 2023 and December 31, 2022, the Company had warrants to purchase the underlying common stock outstanding as shown in the table below. September 30, December 31, Class C Warrants 1,406,977 — Class D Warrants 5,627,906 — 2022 Warrants — 2,034,883 2020 Warrants — 110,248 Pfizer Warrant — 6,320 Warrants to purchase common stock 7,034,883 2,151,451 Weighted-average exercise price per share $ 1.36 $ 31.00

Stock Option and Incentive Plan

Stock Option and Incentive Plans	9 Months Ended
	Sep. 30, 2023
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Incentive Plans	11. Stock Option and Incentive Plans Amended and Restated 2008 Equity Incentive Plan In July 2008, the Company adopted the 2008 Equity Incentive Plan (the “Plan”). On February 26, 2013, the board of directors approved an amended and restated plan (the “Amended Plan”) under which the number of shares of common stock available for issuance was 1,964 . For new awards, the period that vested awards would remain exercisable upon termination of service was reduced from ten years to two years . The board of directors also increased the number of shares of common stock available under the Company’s Amended Plan on February 24, 2014 and April 29, 2014 to 2,321 and 2,946 , respectively. As of the closing of the Company’s IPO, there were no further grants made under the Amended Plan. 2014 Omnibus Incentive Plan In April 2014, the Company’s board of directors adopted the 2014 Omnibus Incentive Plan (the “2014 Plan”). The 2014 Plan was approved by the Company’s shareholders on July 3, 2014. The 2014 Plan allows for the granting of incentive and non-qualified stock options, restricted stock and stock unit awards, stock appreciation rights and other performance-based awards to the Company’s employees, members of the board of directors and consultants of the Company. On July 28, 2014, the effective date of the 2014 Plan, the number of shares of common stock reserved pursuant to the 2014 Plan was 715 . The 2014 Plan provides for an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ended December 31, 2015 and ending on January 1, 2024, equal to the lesser of (i) 4 % of the outstanding shares of common stock on December 31 immediately preceding such date or (ii) a lesser amount determined by the Company’s board of directors. Consistent with the provision for an annual increase, an additional 77,157 shares of common stock have been reserved under the 2014 Plan as of January 1, 2023. 2021 Employment Inducement Omnibus Incentive Plan In September 2021, the Company’s board of directors adopted the 2021 Employment Inducement Omnibus Incentive Plan (the “2021 Plan”), under which the number of shares of common stock reserved for issuance was 12,500 . The 2021 Plan allows for the granting of non-qualified stock options, restricted stock and stock unit awards, stock appreciation rights and other performance-based awards only to newly hired employees of the Company who have not previously been an employee or member of the board, or an employee who is being rehired following a bona fide period of non-employment by the Company. 2022 Employee Stock Purchase Plan In March 2022, the Company’s board of directors adopted the 2022 Employee Stock Purchase Plan (the “2022 ESPP”). The 2022 ESPP was approved by the Company’s shareholders on May 17, 2022. The 2022 ESPP allows employees to buy Company stock through after-tax payroll deductions at a discount from market value. One component of the 2022 ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code, whereas the other component authorizes the grant of rights which need not qualify as rights granted pursuant to an “employee stock purchase plan” under Section 423. The number of shares of common stock initially available for issuance under the 2022 ESPP was 10,000 shares of common stock. As of September 30, 2023, no purchase rights were outstanding under the 2022 ESPP. Under the 2022 ESPP, employees may purchase common stock through after-tax payroll deductions. In the absence of a contrary designation, the purchase price will be 85 % of the lower of the fair market value of our common stock on the first trading day of an offering period or the last trading day of an offering period. The Company recognized compensation expense for stock-based compensation based on the fair value of the underlying instrument. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. A summary of stock option activity for the nine months ended September 30, 2023, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2022 55,565 $ 548.79 Granted 25,188 5.02 Exercised — — Expired ( 1,046 ) 1,763.01 Forfeited ( 125 ) 19.20 Options outstanding at September 30, 2023 79,582 359.68 7.82 $ — Vested and exercisable at September 30, 2023 45,793 $ 532.87 7.04 $ — The fair value of each option grant is estimated on the date of the grant using the Black-Scholes option-pricing model. There were no options granted during the three months ended September 30, 2023. The weighted average grant date fair value of options granted during the three months ended September 30, 2022 was $ 24.00 , and during the nine months ended September 30, 2023 and 2022 was $ 5.02 and $ 244.80 , respectively. Total compensation expense recognized amounted to $ 0.7 million and $ 1.0 million for the three months ended September 30, 2023 and 2022, respectively, and $ 2.4 million and $ 2.9 million for the nine months ended September 30, 2023 and 2022, respectively. As of September 30, 2023, the total remaining unrecognized compensation cost related to unvested stock options was approximately $ 2.2 million which will be recognized over a weighted average period of approximately 1.7 years. The following assumptions were used to compute the fair value of stock options granted during the period: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Risk free interest rate — 3.00 % 4.00 % 2.23 % Expected dividend yield — — — — Expected term (in years) — 5.44 6.06 5.91 Expected volatility — 99.5 % 102.1 % 91.9 % Risk-free interest rate —The Company estimated the risk-free interest rate in reference to yield on U.S. Treasury securities with a maturity date commensurate with the expected term of the associated award. Expected dividend yield— The Company estimated the expected dividend yield based on consideration of its historical dividend experience and future dividend expectations. The Company has not historically declared or paid dividends to common stockholders. Moreover, it does not intend to pay dividends in the future, but instead expects to retain any earnings to invest in its continued growth. Expected term— The Company based expected term on the midpoint of the vesting period and the contractual term of each respective option grant Expected volatility— The Company estimated the expected volatility based on the Company’s historical volatility data.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial information as of September 30, 2023 and for the three and nine months ended September 30, 2023 and 2022 has been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in consolidated financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. The consolidated balance sheet as of December 31, 2022 was derived from the Company’s audited consolidated financial statements, including all related disclosures, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 31, 2023. There have been no material changes to the complete listing of significant accounting policies as described in Note 2 thereof. In the opinion of management, the unaudited financial information as of September 30, 2023 and for the three and nine months ended September 30, 2023 and 2022 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the operating results for the full fiscal year or any future periods.
Principles of Consolidation	Principles of Consolidation The Company has a wholly-owned subsidiary, ContraFect International Limited, in Scotland that establishes legal status for interactions with the European Economic Area. This subsidiary is dormant or is otherwise non-operative. Any inter-company accounts have been eliminated in consolidation.
Significant Risks and Uncertainties	Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to, the results of clinical testing and trial activities of the Company’s products, the Company’s ability to obtain regulatory approval to market its products, competition from products manufactured and sold or being developed by other companies, the price of, and demand for, the Company’s products, the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products, the Company’s ability to raise capital and the effects of COVID-19 and the recent failure of certain financial institutions, on the Company’s business, operations and financial performance and position. The Company currently relies on a single manufacturer of drug substance for each of its product candidates and two manufacturers of drug product, one located in the United States and one in Western Europe, and there are no long-term supply agreements in place. A sustained disruption in the operations of any of these manufacturers, or in the event the Company would need to change to a new supplier, could result in a significant delay in the ability of the Company to complete any associated activities.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. The Company bases estimates and assumptions on historical experience when available and on various factors that it believes to be reasonable under the circumstances. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to stock-based compensation, warrant valuation, research and development accruals and prepaid expenses and realization of net deferred income tax assets. The Company’s actual results may differ from these estimates under different assumptions or conditions.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company’s accounts at Silicon Valley Bank have not experienced any credit losses and the Company does not believe it has material exposure to any significant credit risk on these funds. The Company maintains the majority of its cash, cash equivalents and marketable securities at other financial institutions. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits, marketable securities with maturities of three months or less at purchase, and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value.
Marketable Securities	Marketable Securities Marketable securities consist of investments in corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities . The Company classifies marketable securities available to fund current operations as current assets on its consolidated balance sheets. Marketable securities are classified as long-term assets on the consolidated balance sheets if (i) the Company has the intent and ability to hold the investments for a period of at least one year and (ii) the contractual maturity date of the investments is greater than one year. Marketable securities, together with accrued interest receivable, net of any allowance for credit losses, are recorded at fair value on the consolidated balance sheet, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ deficit and a component of total comprehensive loss in the consolidated statements of comprehensive loss, until realized. The fair value of these securities is based on quoted prices for identical or similar assets. Realized gains and losses are included in interest income in the consolidated statement of operations on a specific-identification basis. There were no realized gains or losses on sales of marketable securities for the nine months ended September 30, 2023 or 2022. The Company held no marketable securities as of September 30, 2023. There were no marketable securities that had been in an unrealized loss position for more than 12 months as of December 31, 2022. The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts payable, accrued liabilities and warrant liabilities. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of judgment and therefore cannot be determined with precision. The fair value of the Company’s warrant liabilities is based upon unobservable inputs, as described further below. The Company discloses information on all assets and liabilities reported at fair value using a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2—Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3—Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The Company had no liabilities classified as Level 1 or Level 2. The carrying amounts reported in the accompanying financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short-term maturities. The fair value of the warrant liabilities is discussed in Note 4, “Fair Value Measurements.”
Stock-based Compensation	Stock-based Compensation Stock-based compensation is measured and recognized as compensation expense for all stock-based payment awards made to employees, directors, and non-employees, including employee stock options. Compensation expense based on the grant date fair value is generally amortized over the requisite service period of the award on a straight-line basis. The fair value of options is calculated using the Black-Scholes option pricing model on the date of grant based on key assumptions such as stock price, risk free interest rates, expected volatility, expected term, and expected dividend yield. The Company’s estimates of these assumptions are based on historical data and judgment regarding future trends and factors
Government Contracts and Grant Agreements	Government Contracts and Grant Agreements On March 10, 2021, the Company entered into a cost-share contract (the “BARDA Contract”) with BARDA, a division of the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response. The base period for the BARDA Contract included government funding of up to $ 9.8 million to reimburse expenses to support the conduct of the Phase 3 DISRUPT study and futility analysis. In connection with the Trial Closure, the BARDA Contract was modified to provide for up to $ 6.6 million in funding to support a futility outcome root-cause analysis and the close-out of the Phase 3 DISRUPT study of exebacase. The BARDA Contract ended on July 31, 2023. The Company recognizes a receivable in other current assets with a related reduction in its research and development expenses when the actual reimbursable costs have been incurred and the Company has complied with the conditions of the applicable government contract or grant agreement and the amounts will be received. The Company recognized a reduction to its research and development expense in the amount of less than $ 0.1 million and $ 0.9 million for the three months ended September 30, 2023 and 2022, and $ 3.2 million and $ 5.2 million for the nine months ended September 30, 2023 and 2022, respectively. The receivable for government contracts and grant agreements as of September 30, 2023 and December 31, 2022 was less than $ 0.1 million and $ 2.6 million, respectively. The Company has $ 2.0 million of committed grant agreement funding remaining as of September 30, 2023.
Restructuring	Restructuring The Company has made estimates and judgments regarding the amount and timing of its restructuring expense and liability, including current and future period termination benefits and other costs to be incurred when related actions take place. Actual results may differ from these estimates. Restructuring charges are reflected in the Company’s consolidated statements of operations.
Net Loss Per Share	Net Loss Per Share Basic net loss per share applicable to common stockholders is calculated by dividing net loss applicable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share applicable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the dilutive net loss per share applicable to common stockholders’ calculation, stock options and warrants are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Credit Losses On January 1, 2023, the Company adopted Accounting Standards Update No. 2016-13, Financial Instruments-Credit Losses (ASU 2016-13). ASU 2016-13 amended the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the “incurred loss” model with an “expected loss” model. Accordingly, these financial assets will be presented at the net amount expected to be collected. This new standard also requires that credit losses related to available-for-sale debt securities be recorded through an allowance for such losses rather than reducing the carrying amount under the current, other-than-temporary-impairment model. The adoption of the new guidance did not affect the Company’s consolidated financial statements.

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	Marketable securities at December 31, 2022 consisted of the following (in thousands): Marketable Securities Amortized Cost Unrealized Unrealized Fair Value Current: Corporate debt $ 4,807 $ — $ ( 32 ) $ 4,775

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following fair value hierarchy table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022 (in thousands): Fair Value Measurement as of September 30, 2023 Quoted Prices Significant Significant Cash equivalents $ 4,086 $ — $ — Marketable securities — — — Warrant liabilities — — 652 Total $ 4,086 $ — $ 652 Fair Value Measurement as of December 31, 2022 Quoted Prices Significant Significant Cash equivalents $ 7,596 $ — $ — Marketable securities 4,775 — — Warrant liabilities — — 9,299 Total $ 12,371 $ — $ 9,299
Reconciliation of Company's Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following tables present a reconciliation of the Company’s financial liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2023 and 2022 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Balance at beginning of period $ 1,861 $ 4,826 $ 9,299 $ 2,530 Issuance of Class C Warrant — — 1,793 — (Decrease) increase in fair value (1) ( 1,209 ) ( 4,823 ) ( 8,998 ) ( 2,527 ) Exercise of underlying warrants (2) — — ( 1,442 ) — Balance at end of period $ 652 $ 3 $ 652 $ 3 (1) The change in fair values of the warrant liabilities is recorded in other income in the consolidated statement of operations. (2) The remaining fair value of the warrant liabilities at the time of exercise was transferred into additional paid-in capital in the consolidated balance sheet.
Class C Warrant [Member]
Assumption Used to Determine Fair Value of Warrant Liability	On June 27, 2023, the Company issued the Class C Warrant pursuant to the Inducement Agreement and determined that this warrant should be classified as a liability and considered as a Level 3 financial instrument (see also Note 9, “Capital Structure”). The Class C Warrant was re-measured at each subsequent reporting period and the changes in fair value have been recognized in the consolidated statement of operations. The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: As of At Issuance Expected volatility 130.0 % 129.1 % Remaining contractual term (in years) 5.17 5.25 Risk-free interest rate 4.60 % 4.02 % Expected dividend yield — % — %
2020 Warrants [Member]
Assumption Used to Determine Fair Value of Warrant Liability	The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability as of December 31, 2022. On May 27, 2023, the 2020 Warrants expired in accordance with their terms and are no longer exercisable. As of Expected volatility 80.2 % Remaining contractual term (in years) 0.42 Risk-free interest rate 4.76 % Expected dividend yield — %
2022 Warrants [Member]
Assumption Used to Determine Fair Value of Warrant Liability	The following assumptions were used in a Black-Scholes option-pricing model to determine the fair value of the warrant liability: Class A Warrants Class B Warrants As of As of As of As of Expected volatility 135.5 % 99.8 % 129.5 % 140.3 % Remaining contractual term (in years) 4.63 5.08 0.13 0.58 Risk-free interest rate 4.13 % 3.99 % 5.32 % 4.76 % Expected dividend yield — % — % —% —%

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Summary of Accrued Liabilities	Accrued and other current liabilities consist of the following as of September 30, 2023 and December 31, 2022 (in thousands): September 30, December 31, Accrued compensation costs $ 1,583 $ 1,676 Accrued professional fees 928 970 Accrued research and development service fees 723 3,443 Accrued insurance and facilities operation expenses 207 252 Other accrued expenses 23 157 Total accrued and other current liabilities $ 3,464 $ 6,498

Net Loss Per Share of Common _2

Net Loss Per Share of Common Stock (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Loss Per Share for Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share for common stockholders (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Net loss $ ( 5,359 ) $ ( 17,067 ) $ ( 14,298 ) $ ( 55,313 ) Weighted average shares of common stock outstanding 10,704,803 491,626 5,559,348 491,626 Net loss per share of common stock—basic and diluted $ ( 0.50 ) $ ( 34.72 ) $ ( 2.57 ) $ ( 112.51 )
Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding	The following potentially dilutive securities outstanding at September 30, 2023 and 2022 have been excluded from the computation of diluted weighted average shares outstanding, as they would have been anti-dilutive: September 30, 2023 2022 Options to purchase common stock 79,582 56,442 Warrants to purchase common stock 7,034,883 116,569 Total 7,114,465 173,011

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Classification of Lease Liabilities	The balance sheet classification of the Company’s lease liabilities was as follows (in thousands): Description September 30, December 31, Operating lease liabilities: Current portion of lease liabilities $ 680 $ 671 Long-term portion of lease liabilities $ 1,873 $ 2,210
Summary of Future Minimum Lease Payments	As of September 30, 2023, the maturities of our operating lease liabilities were as follows (in thousands): Amount October 1, 2023—December 31, 2023 $ 177 Year ending December 31: 2024 721 2025 736 2026 750 2027 702 Total lease payments 3,086 Less: Present value adjustment ( 533 ) Operating lease liabilities $ 2,553
Lease, Cost	Lease costs under the terms of the Company’s leases for the three and nine months ended September 30, 2023 and 2022 were as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Operating lease cost (1) $ 151 $ 154 $ 451 $ 460 Variable lease costs (2) 47 66 98 147 Total lease cost $ 198 $ 220 $ 549 $ 607 (1) Operating lease payments included in the measurement of the Company’s lease liabilities are comprised of fixed payments according to the terms of the Company’s leases. (2) Variable lease payments consist of the Company’s utility costs billed by and paid to its landlord. Variable lease payments are presented as operating expenses in the Company’s Consolidated Statement of Operations in the same line item as expense arising from fixed lease payments and in net cash used in operating activities in the Company’s Statement of Cash Flows.

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	The restructuring costs were included in accounts payable and accrued and other current liabilities. Activity for the three and nine months ended September 30, 2023 is summarized as follows (in thousands): Three Months Nine Months Balance at beginning of period $ 3,612 $ 7,143 Payments made ( 2,215 ) ( 5,746 ) Balance at end of period $ 1,397 $ 1,397

Capital Structure (Tables)

Capital Structure (Tables)	9 Months Ended
	Sep. 30, 2023
Stockholders Equity Reverse Stock Split [Abstract]
Summary of Common Stock Reserved for Future Issuance	The Company has reserved for future issuance the following number of shares of common stock as of September 30, 2023 and December 31, 2022: September 30, December 31, Outstanding pre-funded warrants to purchase common stock — 574,937 Outstanding options to purchase common stock 79,582 55,565 Outstanding warrants to purchase common stock 7,034,883 2,151,451 For future issuance under the 2014 Omnibus Incentive Plan 1,099 1,317 For future issuance under the 2021 Employment Inducement Plan 12,375 12,375 7,127,939 2,795,645

Stock Warrants (Tables)

Stock Warrants (Tables)	9 Months Ended
	Sep. 30, 2023
Warrants and Rights Note Disclosure [Abstract]
Schedule of Warrants Outstanding	As of September 30, 2023 and December 31, 2022, the Company had warrants to purchase the underlying common stock outstanding as shown in the table below. September 30, December 31, Class C Warrants 1,406,977 — Class D Warrants 5,627,906 — 2022 Warrants — 2,034,883 2020 Warrants — 110,248 Pfizer Warrant — 6,320 Warrants to purchase common stock 7,034,883 2,151,451 Weighted-average exercise price per share $ 1.36 $ 31.00

Stock Option and Incentive Pl_2

Stock Option and Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2023
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	A summary of stock option activity for the nine months ended September 30, 2023, is summarized as follows: Number of Weighted Weighted Aggregate Options outstanding at December 31, 2022 55,565 $ 548.79 Granted 25,188 5.02 Exercised — — Expired ( 1,046 ) 1,763.01 Forfeited ( 125 ) 19.20 Options outstanding at September 30, 2023 79,582 359.68 7.82 $ — Vested and exercisable at September 30, 2023 45,793 $ 532.87 7.04 $ —
Assumptions to Compute Fair Value of Stock Option Grants	The following assumptions were used to compute the fair value of stock options granted during the period: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Risk free interest rate — 3.00 % 4.00 % 2.23 % Expected dividend yield — — — — Expected term (in years) — 5.44 6.06 5.91 Expected volatility — 99.5 % 102.1 % 91.9 %

Organization and Description _2

Organization and Description of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands								3 Months Ended	9 Months Ended
	Jun. 26, 2023	Mar. 02, 2023	Dec. 15, 2022	Aug. 15, 2022	Jul. 29, 2022	Mar. 22, 2021	May 27, 2020	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Organization And Description Of Business [Line Items]
Accumulated deficit									$ 340,003		$ 325,705
Net cash used in operating activities									(25,618)	$ (36,006)
Number of shares issued							147,471
Exercise Price of Warrants or Rights	$ 1.36
Cash Cash Equivalents And Marketable Securities									$ 5,400
Restructuring charge				$ 7,700	$ 7,700			$ 7,719		$ 7,719
Labor and Related Expense				1,600	1,600
Write-off of prepaid manufacturing costs				$ 6,100	$ 6,100
Proceeds from warrant exercise prior to deducting fees to financial advisor and estimated expenses	$ 9,600
Common Stock [Member]
Organization And Description Of Business [Line Items]
Number of shares issued		128,000	54,375
Class of warrant or right, issued	7,034,883	5,000,000
Sale of stock, price per share		$ 4
Prefunded Warrants [Member]
Organization And Description Of Business [Line Items]
Class of warrant or right, issued		2,372,000	623,919
Maximum [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights	$ 4
Minimum [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights	1.36
Follow-on Offering [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights							$ 392
Public offering price, per unit							$ 356
Stock issued during period, value						$ 150,000
Over-Allotment Option [Member]
Organization And Description Of Business [Line Items]
Number of shares issued						143,750
Public offering price, per unit						$ 400
Proceeds from initial public offer						$ 53,800
Sale of stock, price per share						$ 400
Pre Funded Warrants and Common Stock [Member]
Organization And Description Of Business [Line Items]
Proceeds from issuance or sale of equity		$ 9,100	$ 6,100
Class A warrants [Member] | Common Stock [Member]
Organization And Description Of Business [Line Items]
Class of warrant or right, issued			1,356,589
Class B warrants [Member] | Common Stock [Member]
Organization And Description Of Business [Line Items]
Class of warrant or right, issued			678,294
Class A warrant and Class B warrant [Member]
Organization And Description Of Business [Line Items]
Sale of stock, price per share			$ 10.32
Two Thousand and Twenty Three Offering [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights		$ 4
Number of common stock Called by each warrant or right		2
Two Thousand and Twenty Three Offering [Member] | Prefunded Warrants [Member]
Organization And Description Of Business [Line Items]
Number of common stock Called by each warrant or right		1
Two Thousand And Twenty Two Offering [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights		$ 4	10.32
Sale of stock, price per share			$ 10.32
Proceeds from issuance or sale of equity		$ 9,100
Number of common stock Called by each warrant or right		2
Two Thousand And Twenty Two Offering [Member] | Prefunded Warrants [Member]
Organization And Description Of Business [Line Items]
Number of common stock Called by each warrant or right		1
Two Thousand And Twenty Two Offering [Member] | ClassA Warrant [Member]
Organization And Description Of Business [Line Items]
Number of common stock Called by each warrant or right			1
Two Thousand And Twenty Two Offering [Member] | ClassB Warrant [Member]
Organization And Description Of Business [Line Items]
Number of common stock Called by each warrant or right			2
Class C Warrants [Member] | Common Stock [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights	$ 1.36
Class of warrant or right, issued	1,406,977
New Warrants [Member] | Common Stock [Member]
Organization And Description Of Business [Line Items]
Exercise Price of Warrants or Rights	$ 1.36
Class of warrant or right, issued	5,627,906

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended		9 Months Ended
	Mar. 10, 2021 USD ($)	Sep. 30, 2023 USD ($) Securities	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Securities	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) Securities
Summary Of Significant Accounting Policies [Line Items]
Maturity period of highly liquid investments				three months or less
Realized gains or losses on marketable securities				$ 0	$ 0
Marketable securities		$ 0		$ 0
Number of securities in unrealized loss position for more than 12 months | Securities		0		0		0
Grants receivable recognized			$ 900,000	$ 3,200,000	$ 5,200,000
Grants receivable						$ 2,600,000
Grants remaining to be awarded		$ 2,000,000		2,000,000
BARDA Contract [Member] | Base Period BARDA Funding [Member]
Summary Of Significant Accounting Policies [Line Items]
Total funding receives in future	$ 9,800,000
Barda Extended Contract [Member] | Base Period BARDA Funding [Member]
Summary Of Significant Accounting Policies [Line Items]
Total funding receives in future				6,600,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Grants receivable recognized		100,000
Grants receivable		100,000		100,000
Level 1 [Member]
Summary Of Significant Accounting Policies [Line Items]
Liabilities		0		0
Level 2 [Member]
Summary Of Significant Accounting Policies [Line Items]
Liabilities		$ 0		$ 0

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Detail) - Corporate debt [Member] $ in Thousands	Dec. 31, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Marketable Securities, Amortized Cost	$ 4,807
Marketable Securities, Unrealized Gains	0
Marketable Securities, Unrealized Losses	(32)
Marketable Securities, Fair Value	$ 4,775

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2023 USD ($)
Marketable Securities [Abstract]
Marketable securities	$ 0
Maturity period classified current investments	less than one year

Fair Value Measurements - Infor

Fair Value Measurements - Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		$ 4,775
Warrant liabilities	$ 652	9,299
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	4,086	7,596
Marketable securities		4,775
Total	4,086	12,371
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liabilities	652	9,299
Total	$ 652	$ 9,299

Fair Value Measurements - Assum

Fair Value Measurements - Assumption Used to Determine Fair Value of Warrant Liability (Detail)	Sep. 30, 2023 yr	Jun. 26, 2023 yr	Dec. 31, 2022 yr
Expected Volatility [Member] | Class C Warrant [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability	1.30	1.291
Remaining Contractual term (in years) [Member] | Class C Warrant [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability	5.17	5.25
Risk-free Interest Rate [Member] | Class C Warrant [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability	0.046	0.0402
2020 Warrants [Member] | Expected Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability			0.802
2020 Warrants [Member] | Remaining Contractual term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability			0.42
2020 Warrants [Member] | Risk-free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability			0.0476
2022 Warrants [Member] | Expected Volatility [Member] | Class A warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		1.355	0.998
2022 Warrants [Member] | Expected Volatility [Member] | Class B warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		1.295	14,030
2022 Warrants [Member] | Remaining Contractual term (in years) [Member] | Class A warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		4.63	5.08
2022 Warrants [Member] | Remaining Contractual term (in years) [Member] | Class B warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		0.13	0.58
2022 Warrants [Member] | Risk-free Interest Rate [Member] | Class A warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		0.0413	0.0399
2022 Warrants [Member] | Risk-free Interest Rate [Member] | Class B warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant liability		0.0532	0.0476

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Company's Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at end of period		$ 652	$ 3	$ 652	$ 3
Warrant Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period		1,861	4,826	9,299	2,530
Issuance of Class C Warrant				1,793
(Decrease) increase in fair value	[1]	(1,209)	(4,823)	(8,998)	(2,527)
Exercise of underlying warrants	[2]			(1,442)
Balance at end of period		$ 652	$ 3	$ 652	$ 3
[1] The change in fair values of the warrant liabilities is recorded in other income in the consolidated statement of operations. The remaining fair value of the warrant liabilities at the time of exercise was transferred into additional paid-in capital in the consolidated balance sheet.

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued compensation costs	$ 1,583	$ 1,676
Accrued professional fees	928	970
Accrued research and development service fees	723	3,443
Accrued insurance and facilities operation expenses	207	252
Other accrued expenses	23	157
Total accrued and other current liabilities	$ 3,464	$ 6,498

Accrued and Other Current Lia_4

Accrued and Other Current Liabilities - Additional Information (Detail) - Agreement For Financing Insurance Premium [Member] - USD ($) $ in Millions	Sep. 30, 2023	Feb. 28, 2023
Accrued And Other Current Liabilities [Line Items]
Debt instrument face value		$ 0.9
Short term debt bearing fixed interest rate percentage	6.25%
Other short term debt	$ 0.1

Net Loss Per Share of Common _3

Net Loss Per Share of Common Stock - Additional Information (Detail) - Prefunded Warrants [Member] - shares	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023
Share-based compensation arrangement by share-based payment award, non-option equity instruments, outstanding		0
Common Stock [Member]
Share-based compensation arrangement by share-based payment award, non-option equity instruments, exercised	574,937

Net Loss Per Share of Common _4

Net Loss Per Share of Common Stock - Schedule of Computation of Basic and Diluted Loss Per Share for Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net loss	$ (5,359)	$ (7,568)	$ (1,371)	$ (17,067)	$ (18,089)	$ (20,157)	$ (14,298)	$ (55,313)
Shares used in computing basic net loss per share	10,704,803			491,626			5,559,348	491,626
Basic net loss per share	$ (0.5)			$ (34.72)			$ (2.57)	$ (112.51)
Shares used in computing diluted net loss per share	10,704,803			491,626			5,559,348	491,626
Diluted net loss per share	$ (0.5)			$ (34.72)			$ (2.57)	$ (112.51)

Net Loss Per Share of Common _5

Net Loss Per Share of Common Stock - Schedule of Antidilutive Securities Excluded from Computation of Diluted Weighted Average Shares Outstanding (Detail) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	7,114,465	173,011
Employee Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	79,582	56,442
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities outstanding excluded from the computation of diluted weighted average shares	7,034,883	116,569

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2012 ft² Extensionoptions	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jan. 01, 2019	Dec. 31, 2011 Extensionoptions
Loss Contingencies [Line Items]
Non-cancellable operating lease, expiration date	2027-12			2025-12
Number of lease extension options | Extensionoptions	2						2
Lease renewal termination period	5 years						5 years
Area of space relinquished from lease agreement | ft²	10,912
Milestone payment				$ 800,000
Operating lease, remaining lease term						9 years
Operating lease, discount rate, percent						9.93%
Rockefeller University [Member]
Loss Contingencies [Line Items]
Annual maintenance fees payable after 2018		$ 200,000		$ 200,000
Percentage of royalty on net sales				5%
Regulatory milestone payment		5,000,000		$ 5,000,000
Royalty or sublicense payment		$ 0	$ 0	$ 0	$ 0
License agreement termination notice period				60 days
Period of termination after first commercial sale of first licensed product				10 years
License agreement termination description				Each license agreement terminates upon the later of (i) the expiration or abandonment of the last licensed patent under the license agreement to expire or become abandoned, or (ii) 10 years after the first commercial sale of the first licensed product. The Rockefeller University may terminate any license agreement in the event of a breach of such agreement by the Company or if the Company challenges the validity or enforceability of the underlying patent rights. The Company may terminate any license agreement at any time on 60 days’ notice.

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Classification of Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Operating lease liabilities:
Current portion of lease liabilities	$ 680	$ 671
Long-term portion of lease liabilities	$ 1,873	$ 2,210

Commitments and Contingencies_3

Commitments and Contingencies - Maturities of Operating Lease Liabilities (Detail) $ in Thousands	Sep. 30, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
October 1, 2023-December 31, 2023	$ 177
2024	721
2025	736
2026	750
2027	702
Total lease payments	3,086
Less: Present value adjustment	(533)
Operating lease liabilities	$ 2,553

Commitments and Contingencies_4

Commitments and Contingencies - Lease Cost (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disclosure of Lease of Cost [Abstract]
Operating lease cost	$ 151	$ 154	$ 451	$ 460
Variable lease costs	47	66	98	147
Total lease cost	$ 198	$ 220	$ 549	$ 607

Restructuring - Schedule of Re

Restructuring - Schedule of Restructuring Reserve by Type of Cost (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period	$ 3,612	$ 7,143
Payments made	(2,215)	(5,746)
Balance at end of period	$ 1,397	$ 1,397

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
	Aug. 15, 2022	Jul. 29, 2022	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Restructuring Charges	$ 7,700	$ 7,700	$ 7,719	$ 7,719
Labor and Related Expense	1,600	1,600
Write-off of prepaid manufacturing costs	$ 6,100	$ 6,100
Accounts Payable and Accrued Liabilities, Current					$ 1,400

Capital Structure - Additional

Capital Structure - Additional Information (Detail) $ / shares in Units, $ in Thousands

3 Months Ended

9 Months Ended

12 Months Ended

Jun. 26, 2023 USD ($) $ / shares shares

Mar. 02, 2023 USD ($) $ / shares shares

Feb. 10, 2023

Dec. 15, 2022 USD ($) $ / shares shares

Mar. 22, 2021 USD ($) $ / shares shares

May 27, 2020 USD ($) $ / shares shares

Jul. 25, 2017 USD ($)

Sep. 30, 2023 USD ($)

Sep. 30, 2022 USD ($)

Sep. 30, 2023 USD ($) shares

Sep. 30, 2022 USD ($)

Dec. 31, 2022 USD ($)

Dec. 31, 2020

Class of Stock [Line Items]

Common stock, shares authorized | shares

125,000,000

Number of shares issued | shares

147,471

Net proceeds received | $

$ 48,900

Gross Proceed | $

$ 3,000

Dividends declared or paid | $

$ 0

Warrant exercise price per share | $ / shares

$ 1.36

Proceeds from warrant exercise prior to deducting fees to financial advisor and estimated expenses | $

$ 9,600

Issuance costs allocated to warrants | $

$ 96

Common stock, voting rights

The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings.

Fair value adjustment of warrants | $

$ (1,209)

$ (4,823)

$ (8,998)

$ (2,527)

Stockholders' Equity, Reverse Stock Split

1-for-80

Maximum [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 4

Stockholders' Equity, Reverse Stock Split

1-for-80

Minimum [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 1.36

Stockholders' Equity, Reverse Stock Split

1-for-10

Other Expense [Member]

Class of Stock [Line Items]

Fair value adjustment of warrants | $

$ 4,000

Common Stock [Member]

Class of Stock [Line Items]

Number of shares issued | shares

128,000

54,375

Sale of stock, price per share | $ / shares

$ 4

Class of warrant or right, issued | shares

7,034,883

5,000,000

Inducement Agreement [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 1.36

Proceeds from warrant exercise prior to deducting fees to financial advisor and estimated expenses | $

$ 9,600

Inducement Agreement [Member] | Maximum [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 4

Inducement Agreement [Member] | Minimum [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 1.36

Inducement Agreement [Member] | Common Stock [Member]

Class of Stock [Line Items]

Class of warrant or right, issued | shares

7,034,883

Private Placement [Member]

Class of Stock [Line Items]

Issuance of securities in private placement, Shares | shares

8,427

Follow-on Offering [Member]

Class of Stock [Line Items]

Public offering price, per unit | $ / shares

$ 356

Warrants to purchase shares of common stock | shares

110,603

Warrant exercise price per share | $ / shares

$ 392

Conversion ratio of common stock

0.75

Follow-on Offering [Member] | 2020 Warrants [Member]

Class of Stock [Line Items]

Fair value of warrants | $

$ 31,400

Issuance costs allocated to warrants | $

$ 2,200

Follow-on Offering [Member] | 2022 Warrants [Member]

Class of Stock [Line Items]

Fair value of warrants | $

$ 11,000

Issuance costs allocated to warrants | $

$ 900

Over-Allotment Option [Member]

Class of Stock [Line Items]

Number of shares issued | shares

143,750

Public offering price, per unit | $ / shares

$ 400

Sale of stock, price per share | $ / shares

$ 400

Proceeds from Issuance Initial Public Offering | $

$ 53,800

Class A Warrant and Class B Warrant [Member]

Class of Stock [Line Items]

Sale of stock, price per share | $ / shares

$ 10.32

Pre Funded Warrants and Common Stock [Member]

Class of Stock [Line Items]

Proceeds from issuance or sale of equity | $

$ 9,100

$ 6,100

Two Thousand And Twenty Two Offering [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 4

$ 10.32

Sale of stock, price per share | $ / shares

$ 10.32

Class of warrant purchase percentage

4%

Proceeds from issuance or sale of equity | $

$ 9,100

Number of common stock Called by each warrant or right | shares

2

Stockholders' Equity, Reverse Stock Split

1-for-80

Pfizer Warrants [Member]

Class of Stock [Line Items]

Warrants to purchase shares of common stock | shares

6,320

Warrant exercise price per share | $ / shares

$ 392

Pre-Funded Warrants

Class of Stock [Line Items]

Class of warrant or right, issued | shares

2,372,000

623,919

Pre-Funded Warrants | Two Thousand And Twenty Two Offering [Member]

Class of Stock [Line Items]

Number of common stock Called by each warrant or right | shares

1

Class A warrants [Member] | Two Thousand And Twenty Two Offering [Member]

Class of Stock [Line Items]

Number of common stock Called by each warrant or right | shares

2

Class B warrants [Member] | Two Thousand And Twenty Two Offering [Member]

Class of Stock [Line Items]

Number of common stock Called by each warrant or right | shares

1

Class C Warrant [Member] | Inducement Agreement [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 1.36

Class C Warrant [Member] | Inducement Agreement [Member] | Common Stock [Member]

Class of Stock [Line Items]

Class of warrant or right, issued | shares

1,406,977

Class C Warrant [Member] | Follow-on Offering [Member]

Class of Stock [Line Items]

Fair value of warrants | $

$ 1,800

Issuance costs allocated to warrants | $

$ 100

Class D Warrant [Member] | Inducement Agreement [Member]

Class of Stock [Line Items]

Warrant exercise price per share | $ / shares

$ 1.36

Class D Warrant [Member] | Inducement Agreement [Member] | Common Stock [Member]

Class of Stock [Line Items]

Class of warrant or right, issued | shares

5,627,906

Capital Structure - Summary of

Capital Structure - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Sep. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common Stock reserved for future issuance	7,127,939	2,795,645
Two Thousand Fourteen Omnibus Incentive Plan [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	1,099	1,317
Two Thousand Twenty One Employment Inducement Plan [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	12,375	12,375
Stock Options [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	79,582	55,565
Warrants [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	7,034,883	2,151,451
CFRX Prefunded Warrants [Member]
Class of Stock [Line Items]
Common Stock reserved for future issuance	0	574,937

Stock Warrants - Schedule of Wa

Stock Warrants - Schedule of Warrants Outstanding (Detail) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	7,034,883	2,151,451
Weighted-average exercise price per share	$ 1.36	$ 31
Pfizer Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	0	6,320
Class C Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	1,406,977	0
Class D Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	5,627,906	0
2022 Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	0	2,034,883
2020 Warrants [Member]
Class of Warrant or Right [Line Items]
Shares Underlying Outstanding Warrants	0	110,248

Stock Option and Incentive Pl_3

Stock Option and Incentive Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions

3 Months Ended

9 Months Ended

Jan. 01, 2023

Dec. 31, 2015

Sep. 30, 2023

Sep. 30, 2022

Sep. 30, 2023

Sep. 30, 2022

Dec. 31, 2022

May 17, 2022

Dec. 31, 2021

Jul. 28, 2014

Apr. 29, 2014

Feb. 24, 2014

Feb. 26, 2013

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

7,127,939

7,127,939

2,795,645

Number of common stock shares outstanding

79,582

79,582

55,565

Weighted average grant date fair value of options

$ 24

$ 5.02

$ 244.8

Unrecognized compensation cost related to unvested stock options

$ 2.2

$ 2.2

Weighted average period of unvested stock options

1 year 8 months 12 days

Options, granted

0

Employee Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Compensation expense recognized

$ 0.7

$ 1

$ 2.4

$ 2.9

Amended and Restated 2008 Equity Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

1,964

Termination of service, Period

2 years

2008 Equity Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

2,946

2,321

Termination of service, Period

10 years

2014 Omnibus Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

715

Number of additional shares increases of common stock reserved pursuant to the plan

77,157

2014 Omnibus Incentive Plan [Member] | Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Annual increase of plan, percentage of common stock shares outstanding

4%

2021 Employment Inducement Omnibus Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

12,500

Two Thousand and Twenty Two Employee Stock Purchase Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares of common stock reserved pursuant to the plan

10,000

Number of common stock shares outstanding

0

0

Discount rate from fair value on offering date that participants pay for shares.

85%

Stock Option and Incentive Pl_4

Stock Option and Incentive Plans - Summary of Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Options, Options outstanding, Beginning balance | shares	55,565
Number of Options, Granted | shares	25,188
Number of Options, Exercised | shares	0
Number of Options, Expired | shares	(1,046)
Number of Options, Forfeited | shares	(125)
Number of Options, Options outstanding, Ending balance | shares	79,582
Number of Options, Vested and exercisable, Ending Balance | shares	45,793
Weighted Average Exercise Price, Options outstanding, Beginning balance | $ / shares	$ 548.79
Weighted Average Exercise Price, Granted | $ / shares	5.02
Weighted Average Exercise Price, Exercised | $ / shares	0
Weighted Average Exercise Price, Expired | $ / shares	1,763.01
Weighted Average Exercise Price, Forfeited | $ / shares	19.2
Weighted Average Exercise Price, Options outstanding, Ending balance | $ / shares	359.68
Weighted Average Exercise Price, Vested and exercisable, Ending balance | $ / shares	$ 532.87
Weighted Average Remaining Contractual Life (in years), Options outstanding	7 years 9 months 25 days
Weighted Average Remaining Contractual Life (in years), Vested and exercisable	7 years 14 days
Aggregate Intrinsic value, Options outstanding | $	$ 0
Aggregate Intrinsic value, Vested and exercisable | $	$ 0

Stock Option and Incentive Pl_5

Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Risk free interest rate	0%	3%	4%	2.23%
Expected dividend yield	$ 0	$ 0	$ 0	$ 0
Expected term (in years)		5 years 5 months 8 days	6 years 21 days	5 years 10 months 28 days
Expected volatility	0%	99.50%	102.10%	91.90%