0000950170-23-061566 | 10-Q | XBRL Viewer

Fixed Assets, Net

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

4. Fixed Assets, Net

Fixed assets, net consisted of the following (in thousands):


	SEPTEMBER 30, 2023			DECEMBER 31, 2022
Laboratory equipment	$	1,209		$	1,055
Manufacturing equipment		961			1,201
Furniture and fixtures		159			159
Networking and computer equipment		88			81
Leasehold improvements		3,099			3,057
Total fixed assets	$	5,516		$	5,553
Less: accumulated depreciation		(1,840	)		(1,129	)
Fixed assets, net	$	3,676		$	4,424

Depreciation expense for the three and nine months ended September 30, 2023 was $0.2 million and $0.7 million, respectively. Depreciation and amortization expense for the three and nine months ended September 30, 2022 was $0.2 million and $0.6 million, respectively.

Exclusive Licensing Agreement with a Related Party - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2014	Sep. 30, 2022	Sep. 30, 2022	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development service revenue, related party		$ 31	$ 94
Exclusive Licensing Agreement \| Ventagen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment from related party	$ 1,000
Future payment made upon the achievement of sales	$ 5,000
Commercial purposes at a price of cost plus percentage	25.00%
Upfront license fee				$ 1,000
Exclusive Licensing Agreement \| Ventagen \| Voting Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Related party transactions, ownership percentage	49.50%
Exclusive Licensing Agreement \| Ventagen \| Founders \| Voting Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Related party transactions, ownership percentage	47.00%
Exclusive Licensing Agreement \| Ventagen \| Related Party [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Due from related parties	$ 2,500
Related party costs	$ 4,000

Lease - Summary of Future Lease Payments Under Non-cancellable Leases (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Leases [Abstract]
2023	$ 148
2024	598
2025	613
2026	415
Total future lease payments	1,774
Less: imputed interest	(167)
Operating lease liability	$ 1,607

Fair Value of Financial Assets and Liabilities - Schedule of Information About Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Liabilities:
Warrant liability	$ 433	$ 1,882
Total	433	1,882
Level 3
Liabilities:
Warrant liability	433	1,882
Total	$ 433	$ 1,882

Term Loan

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Term Loan

6. Term Loan

On February 24, 2022, the Company entered into a four-year loan and security agreement (the Loan Agreement) with Silicon Valley Bank (SVB) pursuant to which SVB has agreed to provide term loans to the Company in an aggregate principal amount of up to $25.0 million. The Company borrowed $20.0 million upon entering into the Loan Agreement. The Company could have borrowed up to an additional aggregate principal amount not to exceed $5.0 million, at any time on or prior to December 31, 2022, upon achievement of all of the following milestones, inclusively: (a) positive phase 2 clinical activity data from the Company’s CAN-2409 NSCLC clinical trial, (b) dosing of its first patient in its phase 3 CAN-2409 high-grade glioma clinical trial, and (c) receipt on or prior to December 31, 2022, of net cash proceeds in an amount equal to at least $75.0 million from the issuance and sale of equity securities to investors acceptable to SVB. The Company did not borrow any of the additional aggregate principal amount on or prior to December 31, 2022. The term loan is secured by substantially all of the Company’s properties, rights and assets, except for its intellectual property, which is subject to a negative pledge under the Loan Agreement.

The term loans bear interest at a floating rate per annum equal to the greater of (A) 5.75% and (B) the prime rate (as published in the money rates section of The Wall Street Journal) plus 2.50%. The Company is required to make monthly interest payments, and commencing on February 1, 2024, 24 consecutive installments of principal plus monthly payments of accrued interest. The term loans mature on January 1, 2026. Upon repayment in full of the term loans, the Company will be required to pay a final payment fee equal to 4.50% of the original principal amount of any funded term loan being repaid. The Loan Agreement permits voluntary prepayment of all, but not less than all, of the SVB term loans, subject to a prepayment premium of 1% to 3% based upon the timing of the repayment.

During the three and nine months ended September 30, 2023, the Company recorded interest expense relating to the Loan Agreement of $0.6 million and $1.8 million, respectively. During the three and nine months ended September 30, 2022, the Company recorded interest expense relating to the Loan Agreement of $0.5 million and $1.1 million, respectively. The weighted average effective interest rate as of September 30, 2023 was 10.91%.

The Company incurred $89,000 of debt issuance costs and will incur a $0.9 million final payment fee, which were recorded as debt discount and are being amortized over the term of the Loan Agreement. The scheduled principal payments and net carrying amount of the term loan are as follows (in thousands):


YEAR ENDING DECEMBER 31,
2023 (remaining three months)	$	—
2024		8,870
2025		10,232
2026		898
Total principal		20,000
Final payment fee		900
Less: debt discount		(989	)
Accretion of debt discount		528
Net carrying amount		20,439
Less current portion		(6,100	)
Long-term portion	$	14,339

The carrying value of the Company's term loan approximates fair value.

Stock Options, Restricted Stock and Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 686	$ 743	$ 2,152	$ 1,673
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	270	343	883	542
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 416	$ 400	$ 1,269	$ 1,131

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Fair Value of Financial Assets and Liabilities

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

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


	FAIR VALUE MEASUREMENTS AS OF SEPTEMBER 30, 2023 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Warrant liability		—		—		433		433
Total	$	—	$	—	$	433	$	433


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2022 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Warrant liability		—		—		1,882		1,882
Total	$	—	$	—	$	1,882	$	1,882

Valuation of Warrant Liability

In connection with the November 13, 2018 issuance of Series B convertible preferred stock, the Company issued warrants to purchase shares of common stock of which certain warrants are shown as a liability on the balance sheet, see Note 10. The fair value of the warrant liability was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of the warrant liability uses various valuation methods, including the Monte Carlo method, the option-pricing method, probability-weighted expected return and the hybrid method, all of which incorporate assumptions and estimates, to value the common stock warrants. The hybrid method is often used when a company is expecting a liquidity event in the near future and is a combination of the option-pricing and probability-weighted expected return methods. Estimates and assumptions impacting the fair value measurement include the fair value per share of the underlying shares of common stock, risk-free interest rate, expected dividend yield, expected volatility of the price of the underlying common stock, and the remaining contractual term of the warrants. The most significant assumption in the model impacting the fair value of the common stock warrants is the fair value of the Company’s common stock as of each remeasurement date.

The following table provides a roll forward of the aggregate fair values of the Company’s warrant liability, for which fair value is determined by Level 3 inputs (in thousands):


	SERIES B WARRANT LIABILITY
Balance at December 31, 2022	$	1,882
Change in fair value		(1,449	)
Balance at September 30, 2023	$	433

- Definition

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

+ References + Details

Fixed Assets, Net - Summary of Fixed Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total fixed assets	$ 5,516	$ 5,553
Less accumulated depreciation	(1,840)	(1,129)
Fixed assets, net	3,676	4,424
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	1,209	1,055
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	961	1,201
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total fixed assets	159	159
Networking and Computer Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	88	81
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total fixed assets	$ 3,099	$ 3,057

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities:
Net loss	$ (26,844)	$ (13,711)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	711	557
Impairment of fixed assets	162
Loss on the sale of fixed assets	77
Non-cash stock compensation expense	2,152	1,673
Non-cash lease expense	177	154
Non-cash interest expense	77	66
Change in fair value of warrant liability	(1,449)	(13,626)
Accretion of debt discount	237	211
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(230)	417
Other assets	(139)
Accounts payable	(127)	(669)
Accrued expenses	(1,247)	830
Deferred revenue	(36)	(94)
Lease liability	(343)	(342)
Net cash used in operating activities	(26,822)	(24,534)
Cash Flows from Investing Activities:
Purchase of fixed assets	(410)	(1,021)
Proceeds from the sale of fixed assets	157
Net cash used in investing activities	(253)	(1,021)
Cash Flows from Financing Activities:
Net proceeds from bank term loan		19,910
Proceeds from option exercises		28
Net cash provided by financing activities		19,938
Net decrease in cash	(27,075)	5,617
Cash, cash equivalents and restricted cash at beginning of period	70,324	83,066
Cash, cash equivalents and restricted cash at end of period	43,249	77,449
Supplemental cash flow information:
Cash paid for taxes		156
Cash paid for interest	1,592	843
Supplemental disclosures of non-cash information:
Lease liability arising from obtaining right-of-use assets		2,368
Capital expenditures in accounts payable and accrued expenses	$ 19	261
Common stock exchange for option exercise		$ 448

Stock Options, Restricted Stock and Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock Units	Sep. 30, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Shares Options, Unvested \| shares	612,366
Number of Shares Options, Unvested \| shares	612,366
Weighted-Average Grant Date Fair Value, Unvested \| $ / shares	$ 1.71
Weighted-Average Grant Date Fair Value, Unvested \| $ / shares	$ 1.71

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Accrued Expenses

9 Months Ended

Sep. 30, 2023

Payables and Accruals [Abstract]

Accrued Expenses

5. Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	SEPTEMBER 30, 2023		DECEMBER 31, 2022
Payroll and employee related expenses	$	1,938	$	2,647
Third-party research and development expenses		1,094		1,486
Professional fees and other		397		590
	$	3,429	$	4,723

Other Long-Term Debt

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Other Long-Term Debt

7. Other Long-Term Debt

Periphagen Note

On December 9, 2019, the Company entered into a series of asset purchase agreements with Periphagen, Inc. (Periphagen), a biopharmaceutical company focused on the development of gene therapy vectors. Under the terms of the asset purchase agreements, the Company assumed a $1.0 million promissory note bearing a contractual interest rate of 2% compounded annually, with the outstanding balance and accrued interest due upon maturity in November 2027, with no interim installments due. The estimated market rate for the Company for an unsecured loan with a maturity in November 2027 was determined to be 15.83%. Although the Company does not have a public credit rating, management estimates a CCC credit rating based on the Company’s financial position and stage of development. Using the commensurate rate for a CCC rated company and based on the amount due at maturity, the present value of the future cash outflow was determined to be $0.4 million at the transaction date. As of September 30, 2023, the carrying value of the note is $0.7 million.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

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-Topic 470
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-Section 50
-Paragraph 1I
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Preferred stock par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares, issued	29,042,418	29,042,418
Common stock, shares, outstanding	28,919,810	28,919,810

Common Stock and Preferred Stock (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Schedule of Common Stock Reserved For Future Issuance

Common Stock Reserved

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


	SEPTEMBER 30, 2023		DECEMBER 31, 2022

Stock options outstanding		6,061,521		5,645,420
Unvested restricted stock		612,366		612,366
Shares available for future grant under stock option plan		1,962,770		1,311,915
Warrants		7,507,708		7,507,708
		16,144,365		15,077,409

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Share

Basic and diluted net loss per share was calculated as follows (in thousands except per share amounts):


	THREE MONTHS ENDED SEPTEMBER 30,						NINE MONTHS ENDED SEPTEMBER 30,
Numerator:	2023			2022			2023			2022
Net loss	$	(8,435	)	$	(8,688	)	$	(26,844	)	$	(13,711	)
Denominator:
Weighted-average shares of common stock outstanding - basic and diluted		28,919,810			28,891,909			28,919,810			28,798,284
Net loss per share - basic and diluted	$	(0.29	)	$	(0.30	)	$	(0.93	)	$	(0.48	)

Schedule of Potential Shares of Common Stock Excluded from Computation of Diluted Net Loss Per Share

The Company excluded the following potential shares of common stock from the computation of diluted net loss per share attributable to common stockholders because including them would have had an anti-dilutive effect.


	AS OF SEPTEMBER 30,
	2023		2022
Outstanding warrants for common stock		7,507,708		7,507,708
Outstanding stock options (as converted to common stock)		6,061,521		6,190,505
Unvested restricted stock		612,366		—
		14,181,595		13,698,213

Organization and Basis of Presentation

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Basis of Presentation

1. Organization and Basis of Presentation

Candel Therapeutics, Inc., formerly known as Advantagene, Inc. (the Company), is a clinical stage biopharmaceutical company that was incorporated in Delaware in June 2003. On November 30, 2020, the Company changed its name to Candel Therapeutics, Inc. The Company is focused on developing off-the-shelf viral immunotherapies that elicit an individualized, systemic anti-tumor immune response to help patients fight cancer. The Company’s engineered viruses are designed to induce immunogenic cell death through direct viral-mediated cytotoxicity in cancer cells, thus releasing tumor neo-antigens and creating a pro-inflammatory microenvironment at the site of injection. This leads to in-situ vaccination against the injected tumor and uninjected distant metastases. The Company has established two off-the-shelf viral immunotherapy platforms and its two product candidates, CAN-2409 and CAN-3110, are in clinical trials for a number of tumor types. Additionally, the Company and the University of Pennsylvania (UPenn) are collaborating to study the impact of novel viral immunotherapies based on Candel's propriety enLIGHTEN™ Discovery Platform, a systematic, iterative herpes simplex virus based platform leveraging human biology and advanced analytics, to strengthen the effects of UPenn's investigational CAR-T cell therapies in solid tumors.

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales.

Since inception, the Company has funded its operations primarily with proceeds from the sale of its convertible notes and capital stock and from debt borrowings. The Company has incurred recurring losses since its inception, including a net loss of $26.8 million and $13.7 million for the nine months ended September 30, 2023 and 2022, respectively. In addition, as of September 30, 2023, the Company had an accumulated deficit of $125.9 million. The Company expects to continue to generate operating losses for the foreseeable future.

On July 29, 2021, the Company completed its initial public offering of common stock (the IPO) at which time the Company issued 9,000,000 shares of its common stock at a price to the public of $8.00 per share, and on August 13, 2021, the Company issued an additional 887,994 shares of common stock at $8.00 per share as a partial exercise of the underwriters’ option to purchase additional shares, resulting in net proceeds to the Company of $71.3 million, after deducting underwriting discounts and commissions and offering expenses. Upon closing of the IPO, all outstanding shares of the Company’s convertible preferred stock automatically converted into 7,066,398 shares of common stock.

On August 5, 2022, the Company filed a shelf registration statement on Form S-3 (the Shelf) with the SEC, which covers the offering, issuance, and sale by us of up to an aggregate of $200.0 million of our common stock, preferred stock, debt securities, warrants and/or units of any combination thereof. We simultaneously entered into a sales agreement with Jefferies LLC, as sales agent, to provide for the issuance and sale by us of up to $75.0 million of our common stock from time to time in “at-the-market” offerings under the Shelf (the ATM Program). The Shelf was declared effective by the SEC on August 12, 2022. As of the date hereof, no sales have been made pursuant to the ATM Program.

The Company’s cash and cash equivalents were $43.0 million as of September 30, 2023. In accordance with the Financial Accounting Standards Board (FASB) Accounting Standards Codification, 205-40, Presentation of Financial Statements - Going Concern, management is required to assess the Company’s ability to continue as a going concern for the one-year look forward period following the date that the condensed consolidated financial statements are issued. Based on the Company's current operating plan and existing cash and cash equivalents, the Company has determined that substantial doubt exists regarding its ability to continue as a going concern for the one-year period following the date these condensed consolidated financial statements are issued. To sustain its future operations beyond such one-year period, the Company will require additional funding. The Company expects to finance its cash needs through a combination of public or private equity or debt financings, government grants, and other sources, which may include collaborations, strategic alliances and licensing arrangements with third parties. There is no assurance that the Company will be successful in obtaining sufficient funding on acceptable terms, if at all, and the Company could be forced to delay, reduce, or eliminate some or all of its research, clinical trials, product development or future commercialization efforts, which could materially adversely affect its business prospects or its ability to continue as a going concern.

The accompanying condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. Accordingly, the condensed consolidated financial statements have been prepared on a basis that

assumes the Company will continue as a going concern and that contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

Warrants

9 Months Ended

Sep. 30, 2023

Warrants and Rights Note Disclosure [Abstract]

Warrants

10. Warrants

The Company has the following warrants outstanding for the purchase of common stock as of September 30, 2023 and December 31, 2022:


WARRANTS	SHARES OF COMMON STOCK SUBJECT TO WARRANTS		EXERCISE PRICE PER SHARE		EXPIRATION DATES
Series B Warrants		3,672,484	$	6.81	November 2025
Conditional Series B Warrants		3,672,484	$	6.81	November 2025
NC Ohio Trust		162,740	$	1.46	March 2029

Series B Warrants

In connection with the November 13, 2018 issuance of Series B convertible preferred stock (the Series B Preferred), the Company issued to the purchaser of the Series B Preferred warrants to purchase 3,672,484 shares of common stock for $6.81 per share (the Series B Warrants), which became fully exercisable upon issuance. The Series B Warrants contain provisions allowing cashless exercise.

In addition, the Company issued to the same stockholder additional five-year warrants for the purchase of 3,672,484 shares of common stock for $6.81 per share (the Conditional Series B Warrants), which become exercisable in the event that the Company completes a future financing that meets certain financial milestones or achieves certain share prices as follows:

•

918,121 shares vest upon (1) a financing event effected through the sale of our equity securities to third parties resulting in at least $20,000,000 in gross proceeds, with a per share price of $12.47, or (2) an average market price (determined over a consecutive 10-day period) of $12.47 per share;

•

an additional 918,121 shares vest upon (1) a financing event with a price per share of $13.20, or (2) an average market price (determined over a consecutive 10-day period) of, $13.20 per share;

•

an additional 918,121 shares vest upon (1) a financing event with a per share price of $13.94, or (2) an average market price (determined over a consecutive 10-day period) of, $13.94 per share; and

•

an additional 918,121 shares vest upon (1) a financing event with a per share price of $14.68, or (2) an average market price (determined over a consecutive 10-day period) of, $14.68 per share.

On June 24, 2021, the Company’s board of directors approved and on July 14, 2021 the stockholders approved, effective upon the closing of the IPO, an amendment to the terms of the Series B Warrants and the Conditional Series B Warrants to extend the expiration date from November 2023 to November 2025. In addition, the exercise period for the Conditional Series B Warrants was amended such that in the event the future financing milestones or certain share price targets described above are achieved, the Conditional Series B Warrants can only be exercised in conjunction with the sale of the Company, on a cash or cashless exercise basis, or otherwise in November 2025 through a cashless exercise.

The Company recorded the Series B Warrants as a component of stockholder’s equity at the time of issuance at their estimated fair value of $2.1 million and recorded the Conditional Series B Warrants as a liability on the condensed consolidated balance sheet as the number of shares used to calculate the settlement is not a fixed number of shares. The Conditional Series B Warrants are remeasured to their fair value at each reporting date with changes in the fair value recognized as a component of other income (expense), net in the condensed consolidated statements of operations. The Company will continue to recognize changes in the fair value of the Conditional Series B Warrants until each Conditional Series B Warrant is exercised, expires or qualifies for equity classification. The warrant liability fair value was $0.4 million and $1.9 million as of September 30, 2023 and December 31, 2022, respectively.

NC Ohio Trust Warrants

On March 20, 2019, the Company established the NC Incorporated Ohio Trust, an irrevocable trust funded by the Company. The beneficiary in the trust agreement has provided past services to the Company for more than 15 years and is a non-employee. The warrant provides the beneficiary the right to purchase 162,740 shares of the Company’s common stock, $0.01 par value at an exercise price of $1.46 per share, subject to adjustments as specified in the warrant agreement. The Company recognizes the warrants as compensation expense within the condensed consolidated statement of operations and when the warrants are granted or at the service inception date if the service inception date precedes the grant date. In the period in which the grant date occurs, cumulative compensation cost shall be adjusted to reflect the cumulative effect of measuring compensation cost based on the fair value at the grant date rather than the fair value previously used at the service inception date or subsequent reporting dates. As of September 30, 2023 and December 31, 2022, a grant date was not established as there was not a mutual understanding of key terms. The Company remeasures the fair value of the award at each reporting date, as the service date preceded the grant date. The value of the warrants for 162,740 shares of common stock was $0.1 million and $0.2 million as of September 30, 2023 and December 31, 2022, respectively, and was recorded as stock compensation expense within research and development expense and a credit to stockholders’ equity in the condensed consolidated financial statements.

Warrants (Tables)

6 Months Ended

Jun. 30, 2023

Warrants and Rights Note Disclosure [Abstract]

Summary of Warrants Outstanding for Purchase of Common Stock

The Company has the following warrants outstanding for the purchase of common stock as of September 30, 2023 and December 31, 2022:


WARRANTS	SHARES OF COMMON STOCK SUBJECT TO WARRANTS		EXERCISE PRICE PER SHARE		EXPIRATION DATES
Series B Warrants		3,672,484	$	6.81	November 2025
Conditional Series B Warrants		3,672,484	$	6.81	November 2025
NC Ohio Trust		162,740	$	1.46	March 2029

Organization and Basis of Presentation - Additional Information (Details)			3 Months Ended		9 Months Ended
	Aug. 05, 2022 USD ($)	Jul. 29, 2021 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Candidate $ / shares shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Aug. 13, 2021 $ / shares shares
Organization And Basis Of Presentation [Line Items]
Number of product candidates \| Candidate					2
Net loss			$ (8,435,000)	$ (8,688,000)	$ (26,844,000)	$ (13,711,000)
Accumulated deficit			$ (125,933,000)		$ (125,933,000)		$ (99,089,000)
Common stock, shares, issued \| shares			29,042,418		29,042,418		29,042,418
Common stock par value \| $ / shares			$ 0.01		$ 0.01		$ 0.01
Cash and cash equivalents			$ 42,983,000		$ 42,983,000		$ 70,058,000
IPO
Organization And Basis Of Presentation [Line Items]
Common stock, shares, issued \| shares		9,000,000
Common stock par value \| $ / shares		$ 8
Net proceeds		$ 71,300,000
Convertible preferred stock converted into common stock \| shares		7,066,398
Underwriters’ Overallotment Option
Organization And Basis Of Presentation [Line Items]
Common stock, shares, issued \| shares								887,994
Common stock par value \| $ / shares								$ 8
Combination of Common Stock, Preferred Stock, Debt Securities, Warrants and/or Units \| Maximum [Member]
Organization And Basis Of Presentation [Line Items]
Stock Issued During Period, Value, New Issues	$ 200,000,000
ATM Program \| Maximum [Member]
Organization And Basis Of Presentation [Line Items]
Stock Issued During Period, Value, New Issues	$ 75,000,000

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Nov. 01, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Entity Registrant Name	CANDEL THERAPEUTICS, INC.
Entity Central Index Key	0001841387
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		28,919,810
Entity File Number	001-40629
Entity Tax Identification Number	52-2214851
Entity Address, Address Line One	117 Kendrick St
Entity Address, Address Line Two	Suite 450
Entity Address, City or Town	Needham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02494
Entity Incorporation, State or Country Code	DE
City Area Code	617
Local Phone Number	916-5445
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	CADL
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared in accordance with accounting standards set by the Financial Accounting Standards Board (FASB). The FASB sets generally accepted accounting principles (GAAP) that the Company follows to ensure its financial condition, results of operations, and cash flows are consistently reported. References to GAAP issued by the FASB in these notes to the financial statements are to the FASB Accounting Standards Codification (ASC). The Company has reclassified certain amounts relating to its prior period results to conform to its current period presentation. These reclassifications have not changed the results of operations of prior periods.

Principles of Consolidation

The condensed consolidated financial statements include the accounts of Candel Therapeutics, Inc. and its wholly owned subsidiary Candel Therapeutics Securities Corporation. All intercompany transactions and balances have been eliminated.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company's chief operating decision maker, the Company's chief executive officer, views the Company's operations and manages its business as a single operating segment. The Company only operates in the United States.

Emerging Growth Company

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the Jobs Act). Under the Jobs Act emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the Jobs Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that is (i) no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the Jobs Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Unaudited Interim Financial Information

The accompanying condensed consolidated balance sheet as of September 30, 2023, the condensed consolidated statements of operations for the three and nine months ended September 30, 2023 and 2022, the condensed consolidated statements of stockholders’ equity for the three and nine months ended September 30, 2023 and 2022, the condensed consolidated statements of cash flows for the nine months ended September 30, 2023 and 2022, and the related interim disclosures are unaudited. These unaudited condensed consolidated financial statements include all adjustments necessary, consisting of only normal recurring adjustments, to fairly state the financial position and the results of the Company’s operations and cash flows for interim periods in accordance with U.S. GAAP. Interim period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K (Form 10-K) on file with the SEC.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and related disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenue and expenses during the reporting period. On an ongoing basis, the Company’s management evaluates its estimates, which include but are not limited to management’s judgments of accrued expenses, valuation of stock-based option awards, valuations of warrants, and income taxes. Actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original final maturities of 90 days or less from the date of purchase to be cash equivalents. Cash and cash equivalents comprise marketable securities with maturities of less than 90 days when purchased. Cash equivalents are reported at fair value.

Restricted Cash

The Company had $0.3 million of restricted cash as of both September 30, 2023 and December 31, 2022, which represents cash held as a security deposit under the terms of the Company’s Needham, Massachusetts facility lease.

Fair Value Measurements

Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•

Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The carrying values of cash and cash equivalents (considered as Level 1 measurements), accounts payable, and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. The carrying value of the Company's term loan approximates fair value due to the variable interest rate. The Company’s warrant liability is carried at fair value and is classified as Level 3 measurement.

Property and Equipment

Property and equipment consist of laboratory and manufacturing equipment, networking and computer equipment, furniture and fixtures and leasehold improvements. Property and equipment are recorded at cost, and depreciated using the straight-line method over the estimated useful lives of the respective assets:


ASSET		ESTIMATED USEFUL LIFE
Networking and computer equipment		5 years
Laboratory equipment		5 years
Manufacturing equipment		5 years
Furniture and fixtures		5 years
Leasehold improvements		Shorter of the useful life or remaining lease term

Leases

The Company adopted ASC 842 as of January 1, 2022 and elected the transition method under ASU 2016-02 whereby the Company records a right-of-use asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. The Company also elected to apply the practical expedients intended to ease transition. Accordingly, the Company has only applied ASC 842 to leases existing as of January 1, 2022. The Company determines if an arrangement is, or contains, a lease at inception.

Lease right of use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Lease right of use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments to be made over the lease term. The lease right of use asset is equal to the lease liability and adjusted for prepaid rent, initial direct costs, and incentives. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term. The Company has elected to not apply the recognition requirements of ASC 842 for short-term leases, which is defined as a lease that, at the lease commencement date, has a lease term of 12 months or less and does not include an option to purchase the underlying asset that the Company is reasonably certain to exercise.

For real estate lease agreements entered into or modified after the adoption of ASC 842 that include lease and non-lease components, the Company has elected to account for the lease and non-lease components, such as common area maintenance charges, as a single lease component term.

Concentrations of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Periodically, the Company maintains deposits in accredited financial institutions in-excess of the federally insured limits. The Company deposits its cash in financial institutions with a high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal risk associated with commercial banking relationships.

Impairment of Long-lived Assets

Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. Long-lived assets consist of fixed assets and operating lease assets.

In the third quarter of 2023, the Company recorded an impairment charge of approximately $0.2 million related to manufacturing equipment that the Company has determined it does not plan to use for its intended use, and the Company recorded a reserve to reduce the carrying value to its estimated fair value. The Company has not recorded any other impairment losses on such long-lived assets.

Revenue Recognition

The Company applies Accounting Standards Codification (ASC), Topic 606, Revenue from Contracts with Customers, (ASC 606). This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and then assesses whether or not each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

Research and Development Costs and Accruals

Research and development expenses include salaries and benefits, materials and supplies, preclinical and clinical trial expenses, stock-based compensation expense, depreciation of equipment, contract services and other outside expenses. The Company has entered into various research and development-related contracts with clinical and research institutions, contract research organizations, and other companies. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. Costs of certain development activities, such as manufacturing, pre-clinical and clinical trial expenses, are recognized based on an evaluation of the progress to completion of specific tasks. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development costs. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized. The capitalized amounts are expensed as the related goods are delivered or the services are performed. Costs incurred in obtaining technology licenses and intellectual property are charged to research and development expenses as acquired in-process research and development if the technology licensed or intellectual property acquired has not reached technological feasibility and has no alternative future use.

Patent Costs

All patent-related costs incurred in connection with preparing, filing, maintaining and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified in general and administrative expenses.

Stock-Based Compensation

The Company accounts for its stock-based compensation in accordance with ASC Topic 718, Compensation—Stock Compensation (ASC 718). ASC 718 requires all share-based payments to employees and directors to be recognized as expense in the consolidated statements of operations based on their grant date fair values. In addition, in accordance with FASB Accounting Standards Update (ASU) 2016-09 which identifies areas for simplification of several areas of share-based payment transactions, the Company treats non-employee grants the same as employee grants. The Company estimates the fair value of options granted using the Black-Scholes option pricing model for stock option grants to both employees and non-employees. The Company believes the fair value of the stock options granted to non-employees is more reliably determinable than the fair value of the services provided.

The Black-Scholes option pricing model requires inputs based on certain subjective assumptions, including (a) the expected stock price volatility, (b) the expected term of the award, (c) the risk-free interest rate and (d) expected dividends. Due to a lack of company-specific historical and implied volatility data, the Company has based its computation of expected volatility on the historical volatility of a representative group of public companies with similar characteristics to the Company, including stage of product development and life science industry focus. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. For options granted to non-employees, the Company utilizes the contractual term of the share-based payment as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock.

The Company generally expenses the fair value of its share-based compensation awards to employees and non-employees on a straight-line basis over the requisite service period, which is generally the vesting period.

Government Grants

The Company has applied for grants for the reimbursement of expenditures with the Massachusetts Life Sciences Center for certain qualified operating expenditures, including employee related costs. The Company recognizes government grants when there is reasonable assurance that the Company will comply with the conditions attached to the grant arrangement and the grant will be received.

Government grants are recorded as grant income and classified in other income in the condensed and consolidated statements of operations. The Company recognized government grants of $12,000 and $36,000 for the three and nine months ended September 30, 2023, respectively. The Company did not recognize any government grants for the three and nine months ended September 30, 2022. Grant income is recognized as a component of other income (expense), net in the condensed consolidated statements of operations.

Income Taxes

The Company accounts for income taxes using the asset and liability method in accordance with ASC Topic 740, Income Taxes (ASC 740) which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are determined on the basis of the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. At September 30, 2023 and December 31, 2022, the Company has concluded that a full valuation allowance is necessary for its deferred tax assets (see Note 12).

The Company accounts for uncertainty in income taxes by applying the two-step process to determine the amount of tax benefit to be recognized in the financial statements. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax is then assessed as the amount of benefits to be recognized in the consolidated financial statements. The amount of benefits that may be used are the largest amounts that have a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves or unrecognized tax benefits that are considered appropriate, as well as the related net interest received.

Net Loss Per Share

Basic net loss per share is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share is computed using the weighted-average number of shares of common stock outstanding during the period and, if dilutive, the weighted-average number of potential shares of common stock. In periods where the Company reports a net loss attributable to common stockholders, diluted net loss per share is the same as basic net loss per share, since dilutive shares of common stock are not assumed to have been issued if their effect is anti-dilutive. Diluted net loss per share is the same as basic net loss per share for the three and nine months ended September 30, 2023 and 2022 since all potential shares of common stock instruments are anti-dilutive as a result of the loss for such periods.

Fair Value of Financial Assets and Liabilities - Schedule of Aggregate Fair Values of Warrant Liabilities, for Which Fair Value Determined by Level 3 Inputs (Details) - Series B Warrant Liability $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2022	$ 1,882
Change in fair value	(1,449)
Balance at September 30, 2023	$ 433

Stock Options, Restricted Stock and Stock-Based Compensation

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock Options, Restricted Stock and Stock-Based Compensation

11. Stock Options, Restricted Stock and Stock-Based Compensation

Equity Incentive Plans

The Company’s 2015 Stock Plan, as amended, (the 2015 Plan) provides for the Company to sell or issue common shares or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the board of directors and consultants of the Company. The 2015 Plan is administered by the board of directors and exercise prices, vesting and other restrictions are determined at its discretion. All stock option grants are non-statutory stock options except option grants to employees intended to qualify as incentive stock options under the Internal Revenue Code of 1986, as amended. Incentive stock options may not be granted at less than the fair market value of the Company’s common stock on the date of grant, as determined in good faith by the board of directors at its sole discretion. Nonqualified stock options may be granted at an exercise price established by the board of directors at its sole discretion and the vesting periods may vary. Vesting periods are generally four years and are determined by the board of directors. Stock options become exercisable as they vest. Options granted under the 2015 Plan expire no more than ten years from the date of grant. As of September 30, 2023, there are no shares available for grants under the 2015 Plan and the 2015 Plan continues to govern the terms and conditions of the outstanding awards under the 2015 Plan.

On July 14, 2021, the Company’s 2021 Equity Incentive Plan (the 2021 Plan) was approved by the Company’s stockholders, and became effective upon completion of the IPO and serves as the successor to the 2015 Plan. 5,218,292 shares of common stock are reserved under the 2021 Plan, of which 1,962,770 shares remain available for future grants as of September 30, 2023.

Stock Options

Stock option activity is summarized as follows:


	NUMBER OF STOCK OPTIONS			WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS)		AGGREGATE INTRINSIC VALUE
Outstanding as of December 31, 2022		5,645,420		$	2.77
Granted		1,289,203			1.30
Exercised		—			—
Cancelled, forfeited or expired		(873,102	)		2.58
Outstanding as of September 30, 2023		6,061,521		$	2.49		7.23		—
Exercisable as of September 30, 2023		3,478,354		$	2.46		6.08		—
Unvested as of September 30, 2023		2,583,167		$	2.53		8.78		—

The 2015 Plan, permits participants to use common stock they previously acquired to pay for the exercise of stock options based upon the fair value on the date of exercise. In connection with the exercise of a stock options to purchase 306,518 shares of our common stock at an exercise price of $1.46, option holders tendered 122,608 shares of our common stock previously acquired in consideration of the full aggregate exercise price in accordance with the terms of the option and the 2015 Plan. The shares tendered are recorded as treasury stock within the Company's condensed and consolidated financial statements at September 30, 2023.

The fair value of stock options granted was estimated on the grant date using the Black-Scholes option pricing model based on the following weighted-average assumptions:


	NINE MONTHS ENDED SEPTEMBER 30,
	2023			2022
Expected option life (years)	5.48 - 6.08			6.00 - 6.08
Risk-free interest rate	3.50% - 4.61%			1.69% - 4.02%
Expected volatility	91.33% - 94.51%			85.09% - 86.89%
Expected dividend yield		0	%		0	%
Exercise price	$0.92 - $2.57			$3.10 - $5.19
Fair value of common stock	$0.92 - $2.57			$3.10 - $5.19

The total intrinsic value of stock options vested during the nine months ended September 30, 2023 and 2022 was zero and $1.0 million, respectively.

Restricted Stock Units

Under the terms of the restricted stock unit agreements covering the common stock, shares of common stock related to restricted stock units are subject to time-based vesting. The restricted stock units will immediately be forfeited to the Company if the relationship between the recipient and the Company ceases.

Restricted stock activity is summarized as follows:


	NUMBER OF SHARES		WEIGHTED- AVERAGE GRANT DATE FAIR VALUE
Unvested at December 31, 2022		612,366	$	1.71
Granted		—	$	—
Vested		—	$	—
Forfeited		—	$	—
Unvested at September 30, 2023		612,366	$	1.71

The aggregate fair value of restricted stock units that vested during the nine months ended September 30, 2023 was zero.

Stock-Based Compensation

Stock-based compensation expense for the three and nine months ended September 30, 2023 and 2022 was classified in the condensed consolidated statements of operations as follows:


	THREE MONTHS ENDED SEPTEMBER 30,				NINE MONTHS ENDED SEPTEMBER 30,
	2023		2022		2023		2022
Research and development	$	270	$	343	$	883	$	542
General and administrative		416		400		1,269		1,131
Total stock-based compensation expense	$	686	$	743	$	2,152	$	1,673

As of September 30, 2023 and 2022, total unrecognized compensation cost related to the unvested stock-based awards was $5.5 million and $7.9 million, respectively. As of September 30, 2023 and 2022, these amounts are expected to be recognized over a weighted average period of 2.57 and 2.36 years, respectively.

Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net loss	$ (8,435)	$ (8,688)	$ (26,844)	$ (13,711)
Denominator:
Weighted-average shares of common stock outstanding - basic	28,919,810	28,891,909	28,919,810	28,798,284
Weighted-average shares of common stock outstanding - diluted	28,919,810	28,891,909	28,919,810	28,798,284
Net loss per share - basic	$ (0.29)	$ (0.3)	$ (0.93)	$ (0.48)
Net loss per share - diluted	$ (0.29)	$ (0.3)	$ (0.93)	$ (0.48)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
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Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Section S99
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-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
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-Publisher FASB
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-60B

Reference 32: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
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Reference 35: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
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Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
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Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
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-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Exclusive Licensing Agreement with a Related Party

9 Months Ended

Sep. 30, 2023

License Agreement [Abstract]

Exclusive licensing agreement with a related party

13. Exclusive licensing agreement with a related party

In March 2014, the Company entered into an exclusive licensing agreement with Ventagen, LLC (Ventagen) which provides Ventagen the right to develop products for commercial sale and distribution within Mexico, Belize, Guatemala, Honduras, El Salvador, Costa Rica, Nicaragua, Panama, Colombia, and Bolivia (the Territory). Ventagen paid the Company $1.0 million upon the signing of the agreement and agreed to a fixed future payment to the Company of $2.5 million. The future payment will be made upon the achievement of $5.0 million of sales of an approved product by Ventagen and is subject to reduction if Ventagen’s costs to develop an approved product exceeds $4.0 million. In addition to the upfront payment and the future payment, Ventagen agreed to purchase from the Company all manufactured product that is required for clinical or commercial purposes at a price of cost plus 25% of the wholesale price of the approved product, subject to a minimum or maximum price. In the event the Company is unable or unwilling to manufacture supply under the terms of the agreement, Ventagen has the right to manufacture its own supply and will be required to pay a fixed fee per dose sold. The Company also agreed to provide certain services to Ventagen related to Ventagen’s development plan. Stockholders of the Company own 49.5% of the voting stock of Ventagen, including 47% by the Company’s founders who are currently significant stockholders of the Company, and trusts for the benefit of their children.

The Company had completely recognized the $1.0 million upfront license fee as research and development service revenue as of December 31, 2022.

Stock Options, Restricted Stock and Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

Stock option activity is summarized as follows:


	NUMBER OF STOCK OPTIONS			WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS)		AGGREGATE INTRINSIC VALUE
Outstanding as of December 31, 2022		5,645,420		$	2.77
Granted		1,289,203			1.30
Exercised		—			—
Cancelled, forfeited or expired		(873,102	)		2.58
Outstanding as of September 30, 2023		6,061,521		$	2.49		7.23		—
Exercisable as of September 30, 2023		3,478,354		$	2.46		6.08		—
Unvested as of September 30, 2023		2,583,167		$	2.53		8.78		—

Schedule of Fair Value of Stock Options Granted Was Estimated on Black-Scholes Options

The fair value of stock options granted was estimated on the grant date using the Black-Scholes option pricing model based on the following weighted-average assumptions:


	NINE MONTHS ENDED SEPTEMBER 30,
	2023			2022
Expected option life (years)	5.48 - 6.08			6.00 - 6.08
Risk-free interest rate	3.50% - 4.61%			1.69% - 4.02%
Expected volatility	91.33% - 94.51%			85.09% - 86.89%
Expected dividend yield		0	%		0	%
Exercise price	$0.92 - $2.57			$3.10 - $5.19
Fair value of common stock	$0.92 - $2.57			$3.10 - $5.19

Summary of Restricted Stock Activity

Restricted stock activity is summarized as follows:


	NUMBER OF SHARES		WEIGHTED- AVERAGE GRANT DATE FAIR VALUE
Unvested at December 31, 2022		612,366	$	1.71
Granted		—	$	—
Vested		—	$	—
Forfeited		—	$	—
Unvested at September 30, 2023		612,366	$	1.71

Schedule of Stock-based Compensation Expense

Stock-based compensation expense for the three and nine months ended September 30, 2023 and 2022 was classified in the condensed consolidated statements of operations as follows:


	THREE MONTHS ENDED SEPTEMBER 30,				NINE MONTHS ENDED SEPTEMBER 30,
	2023		2022		2023		2022
Research and development	$	270	$	343	$	883	$	542
General and administrative		416		400		1,269		1,131
Total stock-based compensation expense	$	686	$	743	$	2,152	$	1,673

Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Schedule of Information About Financial Assets and Liabilities Measured at Fair Value on Recurring Basis


	FAIR VALUE MEASUREMENTS AS OF SEPTEMBER 30, 2023 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Warrant liability		—		—		433		433
Total	$	—	$	—	$	433	$	433


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2022 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Warrant liability		—		—		1,882		1,882
Total	$	—	$	—	$	1,882	$	1,882

Schedule of Aggregate Fair Values of Warrant Liabilities, for Which Fair Value Determined by Level 3 Inputs

The following table provides a roll forward of the aggregate fair values of the Company’s warrant liability, for which fair value is determined by Level 3 inputs (in thousands):


	SERIES B WARRANT LIABILITY
Balance at December 31, 2022	$	1,882
Change in fair value		(1,449	)
Balance at September 30, 2023	$	433

Fixed Assets, Net (Tables)

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Summary of Fixed Assets, Net

Fixed assets, net consisted of the following (in thousands):


	SEPTEMBER 30, 2023			DECEMBER 31, 2022
Laboratory equipment	$	1,209		$	1,055
Manufacturing equipment		961			1,201
Furniture and fixtures		159			159
Networking and computer equipment		88			81
Leasehold improvements		3,099			3,057
Total fixed assets	$	5,516		$	5,553
Less: accumulated depreciation		(1,840	)		(1,129	)
Fixed assets, net	$	3,676		$	4,424

Common Stock and Preferred Stock

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Common Stock and Preferred Stock

9. Common Stock and Preferred Stock

Preferred Stock

The Company has authorized 10,000,000 shares of $0.01 par value preferred stock at September 30, 2023 and December 31, 2022.

Common Stock

The Company has authorized 150,000,000 shares of $0.01 par value common stock at September 30, 2023 and December 31, 2022 of which 29,042,418 were issued as of September 30, 2023 and December 31, 2022. The Company had 28,919,810 outstanding shares as of September 30, 2023 and December 31, 2022. Common shares are voting and dividends may be paid when, as and if declared by the board of directors.

Common Stock Reserved

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


	SEPTEMBER 30, 2023		DECEMBER 31, 2022

Stock options outstanding		6,061,521		5,645,420
Unvested restricted stock		612,366		612,366
Shares available for future grant under stock option plan		1,962,770		1,311,915
Warrants		7,507,708		7,507,708
		16,144,365		15,077,409

Initial Public Offering

The Company completed its IPO on July 29, 2021 and issued 9,000,000 shares of its common stock at a price to the public of $8.00 per share. On August 13, 2021, the Company issued an additional 887,994 shares of its common stock at a price of $8.00 per share pursuant to a partial exercise of the underwriters' purchase option. Total net proceeds to the Company from the issuance of the 9,877,994 shares of common stock were $71.3 million, after deducting underwriting discounts, commissions and offering expenses. Upon closing of the IPO, all outstanding shares of the Company’s Preferred Stock automatically converted into 7,066,398 shares of common stock.

Shelf Registration and At-the-Market Offerings

On August 5, 2022, the Company filed the Shelf with the SEC, which covers the offering, issuance, and sale by us of up to an aggregate of $200.0 million of our common stock, preferred stock, debt securities, warrants and/or units of any combination thereof. We simultaneously entered into a sales agreement with Jefferies LLC, as sales agent, to provide for the issuance and sale by us of up to $75.0 million of our common stock from time to time in “at-the-market” offerings under the Shelf. The Shelf was declared effective by the SEC on August 12, 2022. Due to the SEC’s “baby shelf rules,” which prohibit companies with a public float of less than $75.0 million from issuing securities under a shelf registration statement in excess of one third of such company’s public float in a 12-month period, the Company is currently only able to issue a limited number of shares which aggregate to no more than one-third of its public float using the Shelf. As of the date hereof, no sales have been made pursuant to the ATM Program.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

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

Principles of Consolidation

Segment Information

Emerging Growth Company

Unaudited Interim Financial Information

Use of Estimates

Cash and Cash Equivalents

Restricted Cash

Fair Value Measurements

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Property and Equipment


ASSET		ESTIMATED USEFUL LIFE
Networking and computer equipment		5 years
Laboratory equipment		5 years
Manufacturing equipment		5 years
Furniture and fixtures		5 years
Leasehold improvements		Shorter of the useful life or remaining lease term

Leases

Concentrations of Credit Risk

Impairment of Long-lived Assets

Revenue Recognition

Research and Development Costs and Accruals

Patent Costs

Stock-Based Compensation

Government Grants

Income Taxes

Net Loss Per Share

Warrants - Additional Information (Details) $ / shares in Units, $ in Thousands			9 Months Ended	12 Months Ended
	Jun. 24, 2021	Mar. 20, 2019 $ / shares shares	Sep. 30, 2023 USD ($) TradingDays $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Jul. 29, 2021 $ / shares	Nov. 13, 2018 $ / shares shares
Class Of Warrant Or Right [Line Items]
Fair value of warrant liability \| $			$ 433	$ 1,882
Common stock, par value			$ 0.01	$ 0.01
IPO
Class Of Warrant Or Right [Line Items]
Common stock, par value					$ 8
Tranche One
Class Of Warrant Or Right [Line Items]
Proceeds from stock offering \| $			$ 20,000,000
Class of warrant or right exercise price per share			$ 12.47
Class of warrant or right exercise average market price per share			$ 12.47
Number of consecutive days \| TradingDays			10
Class of warrants issued \| shares			918,121
Tranche Two
Class Of Warrant Or Right [Line Items]
Class of warrant or right exercise price per share			$ 13.2
Class of warrant or right exercise average market price per share			$ 13.2
Number of consecutive days \| TradingDays			10
Class of warrants issued \| shares			918,121
Tranche Three
Class Of Warrant Or Right [Line Items]
Class of warrant or right exercise price per share			$ 13.94
Class of warrant or right exercise average market price per share			$ 13.94
Number of consecutive days \| TradingDays			10
Class of warrants issued \| shares			918,121
Tranche Four
Class Of Warrant Or Right [Line Items]
Class of warrant or right exercise price per share			$ 14.68
Class of warrant or right exercise average market price per share			$ 14.68
Number of consecutive days \| TradingDays			10
Class of warrants issued \| shares			918,121
Series B Warrants
Class Of Warrant Or Right [Line Items]
Class of warrant or right issued \| shares						3,672,484
Class of warrant or right period			5 years
Class of warrants issued per share			$ 6.81	$ 6.81		$ 6.81
Expiration dates	2023-11		2025-11	2025-11
Estimated fair value of warrants \| $			$ 2,100
Extended expiration dates	2025-11
Class of warrants issued \| shares			3,672,484	3,672,484
Series B Conditional Warrants
Class Of Warrant Or Right [Line Items]
Fair value of warrant liability \| $			$ 400	$ 1,900
Conditional Series B Warrants
Class Of Warrant Or Right [Line Items]
Class of warrants issued per share			$ 6.81	$ 6.81
Expiration dates			2025-11	2025-11
Class of warrants issued \| shares			3,672,484	3,672,484
NC Ohio Trust
Class Of Warrant Or Right [Line Items]
Class of warrants issued per share		$ 1.46	$ 1.46	$ 1.46
Expiration dates			2029-03	2029-03
Class of warrants issued \| shares		162,740	162,740	162,740
Common stock, par value		$ 0.01
Warrant liability \| $			$ 100	$ 200
NC Ohio Trust \| Minimum
Class Of Warrant Or Right [Line Items]
Past services provided by beneficiary		15 years

Term Loan - Schedule of Principal Payments and Net Carrying Amount of Term Loan (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Debt Instrument [Line Items]
2023 (remaining three months)	$ 0
2024	8,870
2025	10,232
2026	898
Total principal	20,000
Final payment fee	900
Less: debt discount	(989)
Accretion of debt discount	528
Net carrying amount	20,439
Less current portion	(6,100)
Long-term portion	$ 14,339

Fixed Assets, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 200		$ 711	$ 557
Depreciation and amortization expense		$ 200		$ 600

Common Stock and Preferred Stock - Additional Information (Details) - USD ($)	Aug. 05, 2022	Jul. 29, 2021	Sep. 30, 2023	Dec. 31, 2022	Aug. 13, 2021
Class of Stock [Line Items]
Preferred stock, shares authorized			10,000,000	10,000,000
Preferred stock par value			$ 0.01	$ 0.01
Common stock, shares authorized			150,000,000	150,000,000
Common stock, par value			$ 0.01	$ 0.01
Common stock, shares, issued			29,042,418	29,042,418
Common stock, shares, outstanding			28,919,810	28,919,810
IPO
Class of Stock [Line Items]
Common stock, par value		$ 8
Common stock, shares, issued		9,000,000
Net proceeds after deducting underwriting discounts and commissions and offering expenses		$ 71,300,000
Convertible preferred stock converted into common stock		7,066,398
Underwriters’ Overallotment Option
Class of Stock [Line Items]
Common stock, par value					$ 8
Common stock, shares, issued					887,994
IPO including Underwriters' Option
Class of Stock [Line Items]
Common stock, shares, issued		9,877,994
Net proceeds after deducting underwriting discounts and commissions and offering expenses		$ 71,300,000
Maximum \| Combination of Common Stock, Preferred Stock, Debt Securities, Warrants and/or Units
Class of Stock [Line Items]
Sale of stock under Shelf	$ 200,000,000
Maximum \| ATM Program
Class of Stock [Line Items]
Sale of stock under Shelf	75,000,000
Public float issuing securities	$ 75,000,000

Common Stock and Preferred Stock - Schedule of Common Stock Reserved For Future Issuance (Details) - shares	Sep. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock reserved for future issuance	16,144,365	15,077,409
Warrants
Class of Stock [Line Items]
Common stock reserved for future issuance	7,507,708	7,507,708
Stock Options Outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance	6,061,521	5,645,420
Unvested Restricted Stock
Class of Stock [Line Items]
Common stock reserved for future issuance	612,366	612,366
Shares Available for Future Grant Under Stock Option Plan
Class of Stock [Line Items]
Common stock reserved for future issuance	1,962,770	1,311,915

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 42,983	$ 70,058
Prepaid expenses and other current assets	2,118	1,887
Total current assets	45,101	71,945
Fixed assets, net	3,676	4,424
Lease right of use assets	879	1,056
Restricted cash	266	266
Other assets	139
Total assets	50,061	77,691
Current liabilities:
Accounts payable	250	380
Accrued expenses	3,429	4,723
Current portion of term loan payable to a bank	6,100
Current portion of lease liability	500	464
Other current liabilities	48	48
Total current liabilities	10,327	5,615
Deferred revenue	108	144
Term loan payable to a bank	14,339	20,202
Other long-term debt	725	648
Lease liability, net of current portion	1,107	1,486
Warrant liability	433	1,882
Total liabilities	27,039	29,977
Commitments and contingencies (Note 15)
Stockholders' equity
Preferred stock, $0.01 par value; 10,000,000 shares authorized at June 30, 2023 and December 31, 2022; no shares issued or outstanding at June 30, 2023 and December 31, 2022, respectively.
Common stock, $0.01 par value; 150,000,000 shares authorized at June 30, 2023 and December 31, 2022; 29,042,418 shares issued at June 30, 2023 and December 31, 2022; 28,919,810 shares outstanding at June 30, 2023 and December 31, 2022.	290	290
Treasury stock (at cost)	(448)	(448)
Additional paid-in capital	149,113	146,961
Accumulated deficit	(125,933)	(99,089)
Total stockholders' equity	23,022	47,714
Total liabilities and stockholders' equity	$ 50,061	$ 77,691

Term Loan - Additional Information (Details)			3 Months Ended		9 Months Ended
Term Loan - Additional Information (Details)	Dec. 30, 2022 USD ($)	Feb. 24, 2022 USD ($) Installment	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Debt Instrument [Line Items]
Loan, maximum borrowing capacity	$ 5,000,000
Long-term debt			$ 20,439,000		$ 20,439,000
Cash proceeds amount equal to at least from the issuance and sale of equity securities	$ 75,000,000
Final payment fee			900,000		900,000
Loan Agreement
Debt Instrument [Line Items]
Loan agreement date		Feb. 24, 2022
Loan, maximum borrowing capacity		$ 25,000,000
Long-term debt		$ 20,000,000
Loan agreement period		4 years
Number of consecutive \| Installment		24
Interest expense			$ 600,000	$ 500,000	$ 1,800,000	$ 1,100,000
Weighted average effective interest rate			10.91%		10.91%
Debt issuance costs			$ 89,000		$ 89,000
Final payment fee			$ 900,000		$ 900,000
Loan Agreement \| Term Loan
Debt Instrument [Line Items]
Debt instrument, payment		monthly
Debt instrument, commencing date		Feb. 01, 2024
Debt instrument, maturity date		Jan. 01, 2026
Debt instrument final payment fee percentage		4.50%
Loan Agreement \| Minimum
Debt Instrument [Line Items]
Debt instrument subject to prepayment premium percentage		1.00%
Loan Agreement \| Minimum \| Prime Rate \| Term Loan
Debt Instrument [Line Items]
Interest rate		2.50%
Loan Agreement \| Maximum
Debt Instrument [Line Items]
Debt instrument subject to prepayment premium percentage		3.00%
Loan Agreement \| Maximum \| Term Loan
Debt Instrument [Line Items]
Interest rate		5.75%

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

15. Commitments and Contingencies

Guarantees

The Company has identified the guarantees described below as disclosable, in accordance with ASC 460, Guarantees.

As permitted under Delaware law, the Company indemnifies its officers and directors for certain events or occurrences while the officer or director is, or was, serving at the Company’s request in such capacity. The maximum potential amount of future payments the Company could be required to make is unlimited; however, the Company has directors’ and officers’ insurance coverage that should limit its exposure and enable it to recover a portion of any future amounts paid.

The Company is a party to a number of agreements entered into in the ordinary course of business that contain typical provisions that obligate the Company to indemnify the other parties to such agreements upon the occurrence of certain events. Such indemnification obligations are usually in effect from the date of execution of the applicable agreement for a period equal to the applicable statute of limitations. The aggregate maximum potential future liability of the Company under such indemnification provisions is uncertain.

The Company leases office space under a noncancelable operating lease expiring in 2026. The Company has standard indemnification arrangements under this lease that require it to indemnify the landlord against all costs, expenses, fines, suits, claims, demands, liabilities, and actions directly resulting from any breach, violation, or nonperformance of any covenant or condition of the lease.

As of September 30, 2023, the Company had not experienced any losses related to these indemnification obligations, and no material claims with respect thereto were outstanding. The Company does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves have been established.

Legal Proceedings

From time to time, we may become involved in litigation or other legal proceedings. On December 15, 2022, Periphagen notified us by letter of its claim that we have failed to use commercially reasonable efforts to complete a human proof of concept clinical trial of an NT-3 Asset under an Exclusive License Agreement dated December 9, 2019 between us and Periphagen (the “Periphagen License Agreement”). On January 13, 2023, we filed a demand for arbitration against Periphagen with the American Arbitration Association, seeking a declaration that Periphagen’s December 15 letter failed to comply with the dispute and escalation provisions in the Periphagen License Agreement. On March 10, 2023, Periphagen filed its answer and counterclaims to our demand for arbitration. In its counterclaims, Periphagen sought a declaration that we have not used commercially reasonable efforts to complete a human proof of concept clinical trial of the NT-3 Asset and a declaration that any further extension of time would not be scientifically or commercially reasonable. We denied Periphagen’s counterclaims.

On June 7, 2023, the parties entered into an amendment to the Exclusive License Agreement that resolved the dispute and resulted in termination of the arbitration.

Aside from the proceeding with Periphagen, we are not currently a party to any litigation or legal proceedings that, in the opinion of our management, are probable to have a material adverse effect on our business. Regardless of outcome, litigation can have an adverse impact on our business, financial condition, results of operations and prospects because of defense and settlement costs, diversion of management resources and other factors.

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock Member	Additional Paid In Capital	Accumulated Deficit
Beginning Balance at Dec. 31, 2021	$ 64,137	$ 286		$ 144,146	$ (80,295)
Beginning Balance, Shares at Dec. 31, 2021		28,689,842
Options exercised	476	$ 4		472
Options exercised, Shares		324,675
Treasury stock acquired	(448)		$ (448)
Treasury stock acquired, Shares			(122,608)
Stock-based compensation	2,309			2,309
Change in fair value of NC Ohio Trust Warrants	(636)			(636)
Net loss	(13,711)				(13,711)
Ending Balance at Sep. 30, 2022	52,127	$ 290	$ (448)	146,291	(94,006)
Ending Balance, Shares at Sep. 30, 2022		29,014,517	(122,608)
Beginning Balance at Jun. 30, 2022	60,072	$ 290	$ (448)	145,548	(85,318)
Beginning Balance, Shares at Jun. 30, 2022		29,014,517	(122,608)
Stock-based compensation	757			757
Change in fair value of NC Ohio Trust Warrants	(14)			(14)
Net loss	(8,688)				(8,688)
Ending Balance at Sep. 30, 2022	52,127	$ 290	$ (448)	146,291	(94,006)
Ending Balance, Shares at Sep. 30, 2022		29,014,517	(122,608)
Beginning Balance at Dec. 31, 2022	$ 47,714	$ 290	$ (448)	146,961	(99,089)
Beginning Balance, Shares at Dec. 31, 2022	28,919,810	29,042,418	(122,608)
Stock-based compensation	$ 2,278			2,278
Change in fair value of NC Ohio Trust Warrants	(126)			(126)
Net loss	(26,844)				(26,844)
Ending Balance at Sep. 30, 2023	$ 23,022	$ 290	$ (448)	149,113	(125,933)
Ending Balance, Shares at Sep. 30, 2023	28,919,810	29,042,418	(122,608)
Beginning Balance at Jun. 30, 2023	$ 30,771	$ 290	$ (448)	148,427	(117,498)
Beginning Balance, Shares at Jun. 30, 2023		29,042,418	(122,608)
Stock-based compensation	735			735
Change in fair value of NC Ohio Trust Warrants	(49)			(49)
Net loss	(8,435)				(8,435)
Ending Balance at Sep. 30, 2023	$ 23,022	$ 290	$ (448)	$ 149,113	$ (125,933)
Ending Balance, Shares at Sep. 30, 2023	28,919,810	29,042,418	(122,608)

- Definition

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

+ References

+ Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

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+ Details

Technology License Agreement

9 Months Ended

Sep. 30, 2023

Technology License Agreement [Abstract]

Technology License Agreement

14. Technology License Agreement

On January 20, 2018 the Company entered into an exclusive option agreement (Option Agreement) with MGB. Pursuant to the Option Agreement, the Company has obtained the exclusive right from MGB to negotiate an exclusive license to make, develop and commercialize rQNestin, a genetically modified oncolytic herpes simplex virus for the treatment of certain types of cancers. Pursuant to the Option Agreement, the Company will support a clinical trial to be conducted at MGB pursuant to the terms of a clinical trial agreement to be negotiated and the Company has committed to remitting $0.8 million in support of such clinical trial over the course of approximately three years. Upon execution of the Option Agreement, the Company remitted a non-refundable fee of $40,000 to MGB to be applied toward the Company’s on-going obligations to reimburse patent expenses. During the nine months ended September 30, 2023 and 2022, the Company did not expense any startup and patient fees for clinical trials performed by MGB.

On September 15, 2020, the Company exercised the Option Agreement with MGB and entered into an exclusive worldwide patent license agreement with MGB (the MGB License). In connection with the MGB License, the Company paid a fee of $0.1 million and agreed to reimburse patent costs incurred by MGB, including $0.1 million paid at the time of entering into the MGB License. Prior to the first commercial sale, the Company is required to pay MGB an annual license fee of $50,000 beginning following the fourth anniversary of the effective date. The MGB License contains cumulative milestone payments equaling a maximum amount of $39.0 million upon the achievement of various clinical, commercial and sales milestones of both primary and secondary products. Following the first commercial sale, the Company is required to pay royalties to MGB, which are paid at an increasing rate as net sales increase, ranging from low single digits to high single digits. In addition, after the first commercial sale, the Company is required to pay MGB a pre-determined fixed annual minimum royalty, which amount may be credited

against earned royalties starting in the fourth year following the first commercial sale. The Company also agreed to pay a single digit royalty rate on net sales of any derived products.

Net Loss Per Share - Schedule of Potential Shares of Common Stock Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	14,181,595	13,698,213
Outstanding Warrants For Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	7,507,708	7,507,708
Outstanding Stock Options (As Converted To Common Stock)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	6,061,521	6,190,505
Unvested Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	612,366	0

Warrants - Summary of Warrants Outstanding for Purchase of Common Stock (Details) - $ / shares		9 Months Ended	12 Months Ended
	Jun. 24, 2021	Sep. 30, 2023	Dec. 31, 2022	Mar. 20, 2019	Nov. 13, 2018
Series B Warrants
Class Of Warrant Or Right [Line Items]
SHARES OF COMMON STOCK SUBJECT TO WARRANTS		3,672,484	3,672,484
EXERCISE PRICE PER SHARE		$ 6.81	$ 6.81		$ 6.81
EXPIRATION DATES	2023-11	2025-11	2025-11
Conditional Series B Warrants
Class Of Warrant Or Right [Line Items]
SHARES OF COMMON STOCK SUBJECT TO WARRANTS		3,672,484	3,672,484
EXERCISE PRICE PER SHARE		$ 6.81	$ 6.81
EXPIRATION DATES		2025-11	2025-11
NC Ohio Trust
Class Of Warrant Or Right [Line Items]
SHARES OF COMMON STOCK SUBJECT TO WARRANTS		162,740	162,740	162,740
EXERCISE PRICE PER SHARE		$ 1.46	$ 1.46	$ 1.46
EXPIRATION DATES		2029-03	2029-03

Net Loss Per Share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

16. Net Loss Per Share

Net Loss Per Share

Basic and diluted net loss per share was calculated as follows (in thousands except per share amounts):


	THREE MONTHS ENDED SEPTEMBER 30,						NINE MONTHS ENDED SEPTEMBER 30,
Numerator:	2023			2022			2023			2022
Net loss	$	(8,435	)	$	(8,688	)	$	(26,844	)	$	(13,711	)
Denominator:
Weighted-average shares of common stock outstanding - basic and diluted		28,919,810			28,891,909			28,919,810			28,798,284
Net loss per share - basic and diluted	$	(0.29	)	$	(0.30	)	$	(0.93	)	$	(0.48	)

The Company’s potentially dilutive securities have been excluded from the computation of dilutive net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of shares of common stock outstanding used to calculate both basic and diluted net loss per share is the same.


	AS OF SEPTEMBER 30,
	2023		2022
Outstanding warrants for common stock		7,507,708		7,507,708
Outstanding stock options (as converted to common stock)		6,061,521		6,190,505
Unvested restricted stock		612,366		—
		14,181,595		13,698,213

Lease (Tables)

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Schedule of Other Information


	NINE MONTHS ENDED SEPTEMBER 30,
Other Information	2023			2022
Operating cash flows used for operating leases	$	434		$	423
Weighted-average remaining lease term (years)		2.9			3.9
Weighted-average incremental borrowing rate		7.02	%		7.02	%

Summary of Future Lease Payments Under Non-cancelable Leases

The future lease payments under non-cancelable leases at September 30, 2023, are as follows (in thousands):


2023	$	148
2024		598
2025		613
2026		415
Total future lease payments		1,774
Less: imputed interest		(167	)
Total lease liability	$	1,607

Technology license agreement - Additional Information (Details) - BWH License - USD ($)			9 Months Ended
	Sep. 15, 2020	Jan. 20, 2018	Sep. 30, 2023	Sep. 30, 2022
Technology License Agreement [Line Items]
Committed amount to remitting in support of clinical trial		$ 800,000
Committed period to remitting in support of clinical trial		3 years
Non-refundable fee		$ 40,000
Expense for startup and patient fees for clinical trials			$ 0	$ 0
Payment for license fee	$ 100,000
Payment at the time of entering into license	100,000
Payment for annual license fee	50,000
Maximum amount upon achievement of various clinical, commercial and sales milestones	$ 39,000,000

Income Taxes - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income tax provisions or benefits	$ 0	$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Income taxes

12. Income taxes

Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. There were no significant income tax provisions or benefits for the nine months ended September 30, 2023 and 2022. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, including our ability to generate taxable income, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following (in thousands):


	SEPTEMBER 30, 2023		DECEMBER 31, 2022
Payroll and employee related expenses	$	1,938	$	2,647
Third-party research and development expenses		1,094		1,486
Professional fees and other		397		590
	$	3,429	$	4,723

Lease - Additional Information (Details)		3 Months Ended		9 Months Ended
Lease - Additional Information (Details)	Feb. 04, 2019 USD ($) Squrefoot	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease cost		$ 90,000	$ 90,000	$ 300,000	$ 300,000
Variable lease cost		35,000	31,000	100,000	100,000
Total lease expense		100,000	100,000	400,000	400,000
Cash paid for amounts included in measurement of lease liability		$ 100,000	$ 100,000	$ 434,000	$ 423,000
Corporate, Clinical and Manufacturing Operations \| Massachusetts
Lessee, Lease, Description [Line Items]
Area of lease property \| Squrefoot	15,197
Lease expiration date	Aug. 31, 2026
Lessee operating lease reimbursement of tenant improvement received	$ 800,000
Lease incentive	$ 800,000

Term Loan (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Principal Payments and Net Carrying Amount of Term Loan

The scheduled principal payments and net carrying amount of the term loan are as follows (in thousands):


YEAR ENDING DECEMBER 31,
2023 (remaining three months)	$	—
2024		8,870
2025		10,232
2026		898
Total principal		20,000
Final payment fee		900
Less: debt discount		(989	)
Accretion of debt discount		528
Net carrying amount		20,439
Less current portion		(6,100	)
Long-term portion	$	14,339

Stock Options, Restricted Stock and Stock-Based Compensation - Schedule of Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number Of Stock Options, Shares Outstanding \| shares	5,645,420
Number Of Stock Options, Shares, Granted \| shares	1,289,203
Number Of Stock Options, Shares, Cancelled or forfeited or expired \| shares	(873,102)
Number Of Stock Options, Shares Outstanding \| shares	6,061,521
Exercisable as of September 30, 2023 \| shares	3,478,354
Unvested as of September 30, 2023 \| shares	2,583,167
Weighted-Average Exercise Price, Outstanding \| $ / shares	$ 2.77
Weighted-Average Exercise Price, Granted \| $ / shares	1.3
Weighted-Average Exercise Price, Cancelled or forfeited or expired \| $ / shares	2.58
Weighted-Average Exercise Price, Outstanding \| $ / shares	2.49
Exercisable as of September 30, 2023 \| $ / shares	2.46
Unvested as of September 30, 2023 \| $ / shares	$ 2.53
Weighted- Average Remaining Contractual Term (In Years), Outstanding	7 years 2 months 23 days
Exercisable as of September 30, 2023	6 years 29 days
Unvested as of September 30, 2023	8 years 9 months 10 days

Summary of Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Details)	Sep. 30, 2023
Significant Accounting Policies [Line Items]
Property, Plant, and Equipment, Useful Life, Term, Description [Extensible Enumeration]	Leasehold Improvements
Networking and Computer Equipment
Significant Accounting Policies [Line Items]
Estimated Useful Life	5 years
Laboratory Equipment
Significant Accounting Policies [Line Items]
Estimated Useful Life	5 years
Manufacturing Equipment
Significant Accounting Policies [Line Items]
Estimated Useful Life	5 years
Furniture and Fixtures
Significant Accounting Policies [Line Items]
Estimated Useful Life	5 years

Commitments and Contingencies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Office space noncancelable operating lease expiration date	2026
Loss related to indemnification obligations	$ 0

Stock Options, Restricted Stock and Stock-Based Compensation - Schedule of Fair Value of Stock Options Granted Was Estimated on Black-Scholes Options (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	5 years 5 months 23 days	6 years
Risk-free interest rate	3.50%	1.69%
Expected volatility	91.33%	85.09%
Exercise price	$ 0.92	$ 3.1
Fair value of common stock	$ 0.92	$ 3.1
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	6 years 29 days	6 years 29 days
Risk-free interest rate	4.61%	4.02%
Expected volatility	94.51%	86.89%
Exercise price	$ 2.57	$ 5.19
Fair value of common stock	$ 2.57	$ 5.19

Other Long-Term Debt - Additional Information (Details) - Periphagen, Inc. - USD ($) $ in Millions	Dec. 09, 2019	Sep. 30, 2023
Debt Instrument [Line Items]
Asset acquisition, assumption of promissory note	$ 1.0
Promissory note contractual interest rate	2.00%
Accrued interest due upon maturity period	2027-11
Estimated market rate for unsecured loan	15.83%
Business acquisition present value of future cash outflow	$ 0.4
Business acquisition carrying value of note		$ 0.7

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147482900/835-30-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Property and Equipment Estimated Useful Lives

Property and equipment are recorded at cost, and depreciated using the straight-line method over the estimated useful lives of the respective assets:


ASSET		ESTIMATED USEFUL LIFE
Networking and computer equipment		5 years
Laboratory equipment		5 years
Manufacturing equipment		5 years
Furniture and fixtures		5 years
Leasehold improvements		Shorter of the useful life or remaining lease term

Lease - Schedule of Other Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
Operating cash flows used for operating leases	$ 100	$ 100	$ 434	$ 423
Weighted-average remaining lease term (years)	2 years 10 months 24 days	3 years 10 months 24 days	2 years 10 months 24 days	3 years 10 months 24 days
Weighted-average incremental borrowing rate	7.02%	7.02%	7.02%	7.02%

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Research and development service revenue, related party		$ 31		$ 94
Operating expenses:
Research and development	$ 5,845	5,376	$ 17,248	15,815
General and administrative	3,016	3,536	10,825	10,900
Total operating expenses	8,861	8,912	28,073	26,715
Loss from operations	(8,861)	(8,881)	(28,073)	(26,621)
Other income (expense):
Grant income	12		36
Interest income	502	343	1,666	414
Interest expense	(669)	(519)	(1,922)	(1,130)
Change in fair value of warrant liability	581	369	1,449	13,626
Total other income (expense), net	426	193	1,229	12,910
Net loss and comprehensive loss	$ (8,435)	$ (8,688)	$ (26,844)	$ (13,711)
Net loss per share - basic	$ (0.29)	$ (0.3)	$ (0.93)	$ (0.48)
Net loss per share - diluted	$ (0.29)	$ (0.3)	$ (0.93)	$ (0.48)
Weighted-average common shares outstanding, basic	28,919,810	28,891,909	28,919,810	28,798,284
Weighted-average common shares outstanding, diluted	28,919,810	28,891,909	28,919,810	28,798,284

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Payroll and employee related expenses	$ 1,938	$ 2,647
Third-party research and development expenses	1,094	1,486
Professional fees and other	397	590
Accrued expenses	$ 3,429	$ 4,723

Lease

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Lease

8. Lease

On February 4, 2019, the Company signed a lease agreement for its new corporate headquarters at 117 Kendrick Street in Needham, Massachusetts. The facility consists of a 15,197 square foot property which houses the corporate, clinical, laboratory and manufacturing operations for the Company. The lease term ends on August 31, 2026. Prior to occupying the new space, the Company had construction performed to modify the space to meet its needs. The Company received $0.8 million as a reimbursement by our landlord for a tenant improvement. The $0.8 million lease incentive was recorded as reduction to the lease right of use asset recorded to the Company's condensed consolidated balance sheet upon adoption of ASC 842 on January 1, 2022.

For the three and nine months ended September 30, 2023, the Company recorded $90,000 and $0.3 million, respectively, of operating lease cost and for the three and nine months ended September 30, 2023, the Company has recorded $35,000 and $0.1 million, respectively, of variable lease cost. The total lease expense for each of the three and nine months ended September 30, 2023 was $0.1 million and $0.4 million, respectively.

For the three and nine months ended September 30, 2022, the Company recorded $90,000 and $0.3 million, respectively, of operating lease cost and for the three and nine months ended September 30, 2022, the Company has recorded $31,000 and $0.1 million, respectively, of variable lease cost. The total lease expense for the three and nine months ended September 30, 2022 was $0.1 million and $0.4 million, respectively.

Cash paid for amounts included in the lease liability for each of the three and nine months ended September 30, 2023 and 2022 was $0.1 million and $0.4 million, respectively.


	NINE MONTHS ENDED SEPTEMBER 30,
Other Information	2023			2022
Operating cash flows used for operating leases	$	434		$	423
Weighted-average remaining lease term (years)		2.9			3.9
Weighted-average incremental borrowing rate		7.02	%		7.02	%

The future lease payments under non-cancelable leases at September 30, 2023, are as follows (in thousands):


2023	$	148
2024		598
2025		613
2026		415
Total future lease payments		1,774
Less: imputed interest		(167	)
Total lease liability	$	1,607

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Segment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segment \| Segment			1
Cash and cash equivalent maturity period			90 days
Restricted cash	$ 300,000		$ 300,000		$ 300,000
Long-lived assets, impairment charge	200,000
Expected dividend assumed			0
Grant revenue	12,000		$ 36,000
Percentage income taxes benefits upon ultimate settlement			50.00%
Government
Significant Accounting Policies [Line Items]
Grant revenue	$ 12,000	$ 0	$ 36,000	$ 0
Maximum
Significant Accounting Policies [Line Items]
Marketable debt securities maturities duration			90 days

Stock Options, Restricted Stock and Stock-Based Compensation - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jul. 14, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	16,144,365		15,077,409
Number of shares available for grants	1,962,770
Intrinsic value of stock options vested	$ 0	$ 1,000,000
Unrecognized compensation cost related to unvested stock options	$ 5,500,000	$ 7,900,000
Stock-based awards are expected to be recognized over a weighted average period	2 years 6 months 25 days	2 years 4 months 9 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate fair value of awards that vested	$ 0
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting period	4 years
Share-based compensation arrangement by share-based payment award, expiration period	10 years
Number of shares available for grants	0
Stock options exercised	306,518
Exercise price per share	$ 1.46
Common stock held by option holder in consideration of aggregate exercise price	122,608
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance				5,218,292