0000950170-22-004857 | 10-K | XBRL Viewer

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Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 82,642	$ 35,053
Prepaid expenses and other current assets	2,303	93
Total current assets	84,945	35,146
Fixed assets, net	3,836	2,787
Other long-term assets	424	349
Total assets	89,205	38,282
Current liabilities:
Accounts payable	1,590	921
Accrued expenses	3,438	3,142
Paycheck protection program loan		463
Other current liabilities	334	187
Total current liabilities	5,362	4,713
Deferred revenue		125
Long-term debt	560	483
Deferred rent	894	632
Warrant liability	18,252	6,831
Total liabilities	25,068	12,784
Commitments and contingencies (Note 15)
Stockholders’ deficit:
Preferred stock, $0.01 par value; 10,000,000 shares authorized at December 31, 2021, no shares issued or outstanding at December 31, 2021
Common stock, $0.01 par value; 150,000,000 and 75,000,000 shares authorized at December 31, 2021 and 2020, respectively, shares issued and outstanding 28,689,842 and 11,635,094 at December 31, 2021 and 2020, respectively.	286	116
Additional paid-in capital	144,146	20,493
Accumulated deficit	(80,295)	(44,171)
Total stockholders' equity (deficit)	64,137	(23,562)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 89,205	38,282
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		26,560
Series C Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		$ 22,500

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Temporary equity, shares authorized		17,187,676
Preferred stock par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	75,000,000
Common stock, shares, issued	28,689,842	11,635,094
Common stock, shares, outstanding	28,689,842	11,635,094
Series B Convertible Preferred Stock
Temporary equity, par value	$ 0.01	$ 0.01
Temporary equity, shares authorized	0	11,155,506
Temporary equity, shares issued	0	11,155,506
Temporary equity, shares outstanding	0	11,155,506
Series C Convertible Preferred Stock
Temporary equity, par value	$ 0.01	$ 0.01
Temporary equity, shares authorized	0	6,032,170
Temporary equity, shares issued	0	6,032,170
Temporary equity, shares outstanding	0	6,032,170

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Research and development service revenue, related party	$ 125	$ 125
Operating expenses:
Research and development	15,178	8,754
General and administrative	10,673	5,181
Total operating expenses	25,851	13,935
Loss from operations	(25,726)	(13,810)
Other income (expense):
Grant income	1,076	624
Interest, dividend and investment income (expense), net	(53)	111
Change in fair value of warrant liability	(11,421)	(4,605)
Total other income (expense), net	(10,398)	(3,870)
Net loss	(36,124)	(17,680)
Other comprehensive gain:
Unrealized gain on available-for-sale securities		19
Comprehensive loss	$ (36,124)	$ (17,661)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.91)	$ (1.52)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	18,873,048	11,615,208

Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Total	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Common Stock	Common Stock Series B Convertible Preferred Stock	Common Stock Series C Convertible Preferred Stock	Additional Paid In Capital	Additional Paid In Capital Series B Convertible Preferred Stock	Additional Paid In Capital Series C Convertible Preferred Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2019	$ (8,038)			$ 116			$ 18,356			$ (19)	$ (26,491)
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019		11,155,506	6,032,170
Temporary Equity, Beginning Balance at Dec. 31, 2019		$ 26,560	$ 22,500
Beginning Balance, Shares at Dec. 31, 2019				11,613,735
Options exercised	$ 30						30
Options exercised, Shares	21,359			21,359
Stock-based compensation	$ 1,412						1,412
Change in fair value of NC Ohio Trust Warrants	695						695
Recognition of unrealized loss on marketable securities	19									$ 19
Net loss	(17,680)										(17,680)
Ending Balance at Dec. 31, 2020	$ (23,562)			$ 116			20,493				(44,171)
Temporary equity, Ending Balance, Shares at Dec. 31, 2020		11,155,506	6,032,170
Temporary equity, Ending Balance at Dec. 31, 2020		$ 26,560	$ 22,500
Ending Balance, Shares at Dec. 31, 2020	11,635,094			11,635,094
Options exercised	$ 35						35
Options exercised, Shares	24,410			24,410
Warrants exercised	$ 430			$ 1			429
Warrants exercised, Shares				75,946
Stock-based compensation	2,588						2,588
Change in fair value of NC Ohio Trust Warrants	375						375
Temporary equity, Conversion of Series Preferred Stock to common stock		$ (26,560)	$ (22,500)
Temporary equity, Conversion of Series Preferred Stock to common stock, Shares		(11,155,506)	(6,032,170)
Conversion of Series Preferred Stock to common stock		$ 26,560	$ 22,500		$ 45	$ 25		$ 26,515	$ 22,475
Conversion of Series Preferred Stock to common stock, Shares					4,538,578	2,527,820
Proceeds from IPO, net	71,335			$ 99			71,236
Proceeds from IPO, net, Shares				9,887,994
Net loss	(36,124)										(36,124)
Ending Balance at Dec. 31, 2021	$ 64,137			$ 286			$ 144,146				$ (80,295)
Temporary equity, Ending Balance, Shares at Dec. 31, 2021		0	0
Ending Balance, Shares at Dec. 31, 2021	28,689,842			28,689,842

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash Flows from Operating Activities:
Net loss	$ (36,124)	$ (17,680)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	232	91
Impairment on manufacturing equipment	553
Non-cash stock compensation expense	2,963	2,107
Non-cash interest expense	76	32
Change in fair value of warrant liability	11,421	4,605
PPP loan forgiveness	(463)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,210)	60
Other long term assets	83	(83)
Accounts payable	669	289
Accrued expenses	297	1,512
Deferred revenue	(125)	(125)
Deferred rent	410	121
Net cash used in operating activities	(22,218)	(9,071)
Cash Flows from Investing Activities:
Purchase of available-for-sale securities		(6)
Proceeds from maturities and sales of available-for-sale securities		39,937
Purchase of fixed assets	(1,835)	(1,476)
Net cash provided by (used in) investing activities	(1,835)	38,455
Cash Flows from Financing Activities:
Proceeds from IPO	71,335
Proceeds from paycheck protection program loan		460
Proceeds from warrant exercises	430
Proceeds from option exercises	35	30
Net cash provided by financing activities	71,800	490
Net increase in cash	47,747	29,874
Cash, cash equivalents and restricted cash at beginning of period	35,319	5,445
Cash, cash equivalents and restricted cash at end of period	83,066	35,319
Supplemental Disclosures of Cash Flow Information:
Cash paid for taxes	$ 29	93
Capital expenditures in accounts payable and accrued expenses		$ 977

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2021

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 late clinical stage biotechnology 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 helping patients fight cancer with oncolytic viral immunotherapies. 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. The Company has established two oncolytic viral immunotherapy platforms and our two product candidates, CAN-2409 and CAN-3110, are in clinical trials for a number of tumor types.

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.

The Company has funded its operations primarily with proceeds from the sale of its capital stock and convertible notes. The Company has incurred recurring losses since its inception, including a net loss of $36,124 and $17,680 for the years ended December 31, 2021, and 2020, respectively. In addition, as of December 31, 2021, the Company had an accumulated deficit of $80,295. 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, or 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 common shares 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 $71,335, 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.

The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. The Company’s inability to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies. There can be no assurances that additional funding will be available on terms acceptable to the Company, or at all. The Company believes that existing resources will fund planned operations for at least 12 months from the date that these consolidated financial statements were available to be issued.

Accordingly, the consolidated financial statements have been prepared on a basis that assumes the Company continue as a going concern and contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

Reverse stock split

On July 14, 2021, the Company’s board of directors and stockholders approved a one-for-2.4579 reverse stock split of the Company’s issued and outstanding common stock and a proportional adjustment to the existing conversion ratios for the outstanding shares of convertible preferred stock which became effective on July 15, 2021. Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of significant accounting policies

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 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).

Principles of consolidation

The 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 (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.

Use of estimates

The preparation of the Company’s 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 share-based awards, valuations of warrants, fair value of debt and income taxes. Actual results could differ from those estimates.

Prior to the IPO, the Company utilized significant estimates and assumptions in determining the fair value of its common stock. The Company has utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation (the Practice Aid), to estimate the fair value of its common stock and warrants. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to the Company’s common stock at the time of, and the likelihood of, achieving a liquidity event, such as an initial public offering or sale. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.

Comprehensive income (loss)

Components of comprehensive income or loss, including net income or loss, are reported in the consolidated financial statements in the period in which they are recognized. Other comprehensive income or loss is defined as the change in equity during a period from transactions and other events and circumstances. Net income (loss) and other comprehensive income (loss) are reported net of any related tax effect to arrive at comprehensive income (loss). Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events. For the period presented, the Company had no elements of other comprehensive loss other than its net loss and unrealized gain on marketable securities.

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 has $424 and $266 of restricted cash as of December 31, 2021 and 2020, respectively, which represents cash held in a restricted bank account under the terms of the Company’s Needham, Massachusetts facility lease and as security for the Company credit card.

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, accounts payable, accrued expenses and Paycheck protection plan loan approximate their fair values due to the short-term nature of these assets and liabilities. The Company’s warrant liability is carried at fair value and is classified as Level 3 measurements (see Note 4). The carrying value of the Company's long-term debt assumed from the Periphagen transaction is classified as Level 3 (See Note 3 and 4).

Property and equipment

Property and equipment consist of 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 accounts for leases in accordance with ASC 840. Rent expense for leases is recognized on a straight-line basis beginning on the date premises were delivered. Minimum lease payments comprise of only base rent.

Concentrations of credit risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and marketable securities. Periodically, the Company maintains deposits and investments 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.

In the fourth quarter of 2021, the Company recorded an impairment charge of approximately $553 related to manufacturing equipment that the Company has determined that it does not plan to use for its intended use and recorded a reserve to reduce the carrying value to its estimated realizable value. The Company has not recorded any other impairment losses on such long-lived assets.

Revenue recognition

The Company applies Accounting Standards Codification, or 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 and comprehensive loss 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.

There are significant judgments and estimates inherent in the determination of the fair value of the Company’s common stock prior to the IPO. These estimates and assumptions included a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to its common stock at the time of, and the likelihood of, achieving a liquidity event, such as an initial public offering or sale.

The Company 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 National Institutes of Health for certain qualified operating expenditures. 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 for research and development efforts are recorded as grant income and classified in other income in the statements of operations and comprehensive loss. The Company recognized government grants of $1,076 and $624 for the years ended December 31, 2021 and 2020, respectively, as a component of other income/(expense), net in the consolidated statements of operations and comprehensive loss.

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 December 31, 2021 and 2020, the Company has concluded that a full valuation allowance is necessary for its deferred tax assets (see Note 11).

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 benefit 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 and penalties.

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. Diluted net loss per share is the same as basic net loss per share for the years ended December 31, 2021 and 2020 since all potential shares of common stock instruments are anti-dilutive as a result of the loss for such periods.

The Company’s convertible preferred stock contractually entitled the holders of such shares to participate in dividends but did not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reported a net loss, such losses will not be allocated to such participating securities. In periods where the Company reported 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. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2021 and 2020.

Recently adopted accounting standards

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. The standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2020 for public companies. The standard was adopted by the Company on January 1, 2021. The Company’s adoption of ASU 2019-12 as of January 1, 2021 did not have an impact on the Company’s financial statements and related disclosures.

Recently issued accounting standards

In February 2016, the FASB issued ASU 2016-02, Leases (“Topic 842”), which requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases. The ASU will also require new qualitative and quantitative disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2021. The Company has substantially completed its assessment of the impact ASU 2016-02 will have on its financial position, results of operations, and related footnotes. The Company expects it will elect to utilize the available package of practical expedients permitted under the transition guidance within the new standard, which does not require the reassessment of the following: i) whether existing or expired arrangements are or contain a lease, ii) the lease classification of existing or expired leases, and iii) whether previous initial direct costs would qualify for capitalization under the new lease standard. Additionally, the Company expects it will make an accounting policy election to keep leases with an initial term of 12 months or less off of its balance sheet. Based on the Company’s initial assessment, this standard will only require capitalization of the lease for its corporate headquarters at 117 Kendrick Street, Needham, Massachusetts. Upon adoption of the standard, the Company expects to record a right of use asset and lease liability of approximately $1,300 and $2,400 respectively on its consolidated balance sheets. The company expects the impact to its consolidated statements of operations and comprehensive loss to be immaterial.

In November 2021, the FASB issued ASU 2021-10 which created Topic 832, Government Assistance, which requires business entities to disclose information about certain government assistance they receive. The ASU requires qualitative and quantitative disclosures around the nature of transactions and related accounting policy used, the line items on the balance sheet and income statement that are affected, and the significant terms and conditions of the transactions. The ASU is effective for fiscal years beginning after December 15, 2021. Based on the Company's initial assessment, the historical disclosure already meets the requirements of the new standard. Upon adoption, the Company will finalize its assessment and update any applicable disclosure as necessary.

Fair Value of Financial Assets and Liabilities

12 Months Ended

Dec. 31, 2021

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:


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2021 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Long-term debt	$	—	$	—	$	560	$	560
Warrant liability		—		—		18,252		18,252
Total	$	—	$	—	$	18,812	$	18,812


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2020 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Long-term debt	$	—	$	—	$	483	$	483
Warrant liability		—		—		6,831		6,831
Total	$	—	$	—	$	7,314	$	7,314

Valuation of long-term debt

The Company’s valuation technique used to measure the fair value of the long-term debt assumed as part of an asset acquisition (see Note 7) was a present value calculation based upon a credit rating estimated for the Company at the time the debt was assumed. The determined credit rating used by the company was CCC based upon the financial position and stage of the Company. The estimated rate was 15.83% for an unsecured note due in November 2027 for a

CCC rated company. The fair value of the long-term debt based on this approach plus the accrued interest represents a Level 3 measurement within the fair value hierarchy.

Valuation of warrant liability

In connection with the Series B Convertible Preferred Stock issuance, 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 9. 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 prior to the IPO, risk-free interest rate, expected dividend yield, expected volatility of the price of the underlying preferred 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. Prior to the IPO, the Company determined the fair value per share of the underlying common stock by taking into consideration the most recent sales of preferred stock, results obtained from third-party valuations and additional factors that are deemed relevant.

The following table provides a roll forward of the aggregate fair values of the Company’s liabilities, for which fair value is determined by Level 3 inputs:


	SERIES B WARRANT LIABILITY		PROMISSORY NOTE
Balance at January 1, 2020	$	2,226	$	420
Change in fair value		4,605		63
Balance at December 31, 2020	$	6,831	$	483
Change in fair value		11,421		77
Balance at December 31, 2021	$	18,252	$	560

- 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

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Fixed assets, net

4. Fixed assets, net

Fixed assets, net consisted of the following:


	DECEMBER 31,
	2021			2020
Construction in progress	$	—		$	1,216
Laboratory equipment		77			24
Manufacturing equipment		933			1,213
Furniture and fixtures		112			112
Networking and computer equipment		72			47
Leasehold improvements		2,994			309
Total fixed assets	$	4,188		$	2,921
Less accumulated depreciation		(352	)		(134	)
Fixed assets, net	$	3,836		$	2,787

Depreciation and amortization expense related to the fixed assets was $232 and $91 for the years ended December 31, 2021 and 2020, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Accrued expenses

5. Accrued expenses

Accrued expenses consisted of the following:


	DECEMBER 31,
	2021		2020
Payroll and employee related expenses	$	2,096	$	1,198
Third-party research and development expenses		632		1,299
Professional fees and other		710		645
	$	3,438	$	3,142

Borrowings under Paycheck Protection Program

12 Months Ended

Dec. 31, 2021

Line Of Credit Facility [Abstract]

Borrowings under Paycheck Protection Program

6. Borrowings under Paycheck Protection Program

On March 27, 2020, President Trump signed the Coronavirus Aid, Relief and Economic Security (the CARES Act), which, among other things, outlines the provisions of the PPP. Section 1106 of the CARES Act contains provisions for the forgiveness of all or a portion of a PPP loan, subject to the satisfaction of certain requirements. The amount eligible for forgiveness is, subject to certain limitations, the sum of the Company’s payroll costs, rent and utilities paid by the Company during the 24-week period beginning on the funding date of the PPP loan.

On April 28, 2020, the Company, as obligor, entered into a promissory note evidencing an unsecured loan in the approximate amount of $460 under the PPP pursuant to the CARES Act. The note matures two years after the date of the loan disbursement and bears interest at a fixed annual rate of 1.00%, with the first six months of principal and interest deferred. Under the terms of the CARES Act, as amended by the Flexibility Act, and the PPP, the Company can apply for and be granted forgiveness for all or a portion of the loan issued under the PPP and the loan is expected to be forgiven to the extent the proceeds are used in accordance with the PPP to cover payroll, mortgage interest, rent, and utility costs incurred by the Company over the 24-week period following the loan disbursement date. In April 2021, the loan of $460 was forgiven and has been recorded as a component of grant income in the consolidated statements of operations and comprehensive loss.

Long-Term Debt

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Long-Term Debt

7. Long-Term Debt

On December 9, 2019, the Company entered into a series of asset purchase agreements with Periphagen, Inc., a biopharmaceutical company focused on the development of gene therapy vectors. Under the terms of the asset purchase agreements, the Company assumed a $1,000 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 $417 at the transaction date. As of December 31, 2021, the present value of future cash flows outflows is $560.

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI http://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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-Paragraph 1B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (g)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Capital Stock

12 Months Ended

Dec. 31, 2021

Capital Stock [Abstract]

Capital Stock

8. Capital stock

Convertible preferred stock

As of December 31, 2020, the Company had authorized 17,187,676 shares of Preferred Stock (the Preferred Stock) and had designated 11,155,506 shares as Series B Convertible Preferred Stock (Series B Preferred) and 6,032,170 shares as Series C Convertible Preferred Stock (Series C Preferred). Since the Preferred Stock was redeemable upon a liquidation event, which was not considered to be within the Company’s control, it has been classified in temporary equity on the accompanying consolidated balance sheets at December 31, 2020. The carrying value of the Preferred Stock is the proceeds received less issuance costs. 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.

Issuances of Preferred Stock

On November 13, 2018, the Company entered into a Series B Preferred Stock Agreement whereby the Company was authorized to issue 11,155,506 shares of Series B Preferred, $0.01 par value, at a purchase price of $2.7696 per share. The Company issued 9,026,618 shares of Series B Preferred for gross proceeds of $25,000. As further consideration, the purchaser of Series B Preferred received two warrants to purchase, in the aggregate, up to 7,344,982 shares of the common stock of the Company for $6.81 per share. See Note 9 for description of the warrants issued in connection with the issuance of the Series B Preferred.

In addition, in November 2018, the Company issued 1,751,658 shares of Series B Preferred as payment of convertible notes and 377,130 shares of Series B Preferred as partial repayment of the outstanding related party notes payable.

On March 13, 2019, the Company entered into the Series C Preferred Stock Agreement whereby the Company issued 6,032,170 shares of Series C Preferred, $0.01 par value, at a purchase price of $3.73 per share for total gross proceeds of $22,500.

The Preferred Stock had the following rights, preferences, privileges and restrictions:

Voting

The holders of Preferred Stock were entitled to vote together with all other holders of the Company’s voting stock on an “as converted” basis on all matters submitted to a vote of the holders. The Series B Preferred and Series C Preferred stockholders voted as separate classes on certain issues that solely affect their rights and privileges.

Conversion

Each share of Preferred Stock was convertible into one share of common stock, subject to change per certain anti-dilution provisions in the Company’s charter and the reverse stock split discussed below. All shares of Preferred Stock were subject to a mandatory conversion into common stock upon the closing of the sale of shares of common stock to the public of at least $25,000 in a firm commitment underwritten public offering pursuant an effective registration statement under the Securities Act of 1933 or upon a vote by or written consent of the requisite number stockholders.

Liquidation preference

Upon a voluntary or involuntary liquidation, dissolution or winding up of the Company, proceeds would have been distributed in the following order:

First, to the holders of the Series C Preferred in an amount for each such share of Series C Preferred equal to the greater of (i) two and one-half times the Series C Preferred original issuance price, plus any dividends declared but unpaid thereon or (ii) such amount per share as would have been payable had all shares of Series C Preferred been converted into common stock immediately prior to such liquidation event. If the Company has insufficient assets to permit payment of such amounts in full, the assets of the Company will be distributed to the holders of Series C Preferred pro rata in proportion to the amounts to which each such holder would otherwise be entitled.

Second, to the holders of the Series B Preferred in an amount for each such share of Series B Preferred equal to the greater of (i) the Series B Preferred original issuance price, plus any dividends declared but unpaid thereon or (ii) such amount per share as would have been payable had all shares of Series B Preferred been converted into common stock immediately prior to such liquidation event. If the Company has insufficient assets to permit payment of such amounts in full, the assets of the Company will be distributed to the holders of Series B Preferred pro rata in proportion to the amounts to which each such holder would otherwise be entitled.

Third, upon the distribution of liquidation preference amounts in full to the holders of Preferred Stock, the remaining assets of the Company available for distribution to stockholders shall be distributed among the common stock pro rata based on the number of shares of common stock held by such holders.

Redemption

The Preferred Stock was not subject to mandatory redemption except in the case of a merger or sale of the Company that has been approved by greater than 50% of the Series C Preferred and the Series B Preferred.

Preferred Stock

The Company has authorized 10,000,000 shares of $0.01 par value preferred stock at December 31, 2021.

Common stock

The Company has authorized 150,000,000 shares of $0.01 par value common stock at December 31, 2021 and had authorized 75,000,000 shares of $0.01 par value common stock at December 31, 2020 of which 28,689,842 and 11,635,094 are issued and outstanding as of December 31, 2021 and 2020, respectively. Common shares are voting and dividends may be paid when, as and if declared by the board of directors, subject to the limitations and preferences of the Preferred Stock.

Common stock reserved

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


	DECEMBER 31,
	2021		2020
Series B Preferred conversion		—		4,538,592
Series C Preferred conversion		—		2,454,196
Stock options outstanding		4,783,333		4,013,311
Shares available for future grant under stock option plan		1,878,997		87,042
Warrants		7,507,708		7,632,518
		14,170,038		18,725,659

Reverse stock split

On July 14, 2021, the Company’s board of directors and stockholders approved a one-for-2.4579 reverse stock split of the Company’s issued and outstanding common stock and a proportional adjustment to the existing conversion ratios for the outstanding shares of convertible preferred stock which became effective on July 15, 2021. Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split.

Initial public offering

The Company completed the IPO, including the partial exercise of the underwriters’ option to purchase additional shares, at which time the Company issued 9,887,994 shares of its common stock at a price to the public of $8.00 per share, resulting in net proceeds to the Company of $71,335, after deducting underwriting discounts and 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.

Warrants

12 Months Ended

Dec. 31, 2021

Warrants And Rights Note Disclosure [Abstract]

Warrants

9. Warrants

The Company has the following warrants outstanding for the purchase of common stock as of December 31, 2021:


WARRANT	SHARES OF COMMON STOCK SUBJECT TO WARRANTS		EXERCISE PRICE PER SHARE		EXPIRATION DATES
Series B Warrants		3,672,484	$	6.81	November 2025
Series B Conditional 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 Preferred, the Company issued warrants to purchase 3,672,484 shares of common stock for $6.81 per share to the purchaser of the Series B preferred (the “Series B Warrants”) which are exercisable upon issuance. In addition, the Company issued to the same stockholder additional five-year warrants for the purchase of 3,672,484 shares of common for $6.81 per share which are only exercisable in the event that the Company completes a future financing that meets certain financial milestones or achieves certain share prices (the “Conditional Series B Warrants”). The Series B Warrants and the Conditional Series B Warrants contain provisions allowing 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 $2,124 and recorded the Conditional Series B Warrants as a liability on the 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 consolidated statements of operations and comprehensive loss. The Company will continue to recognize changes in the fair value of the conditional warrant liability until each Conditional Series B Warrant is exercised, expires or qualifies for equity classification. The Conditional Series B Warrant liability fair value was $18,252 and $6,831 as of December 31, 2021 and 2020, respectively.

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 Warrant and the Conditional Series B Warrants to extend the expiration date from November 2023 to November 2025. In addition, the terms of the Conditional Series B Warrants were amended such that in the event the future financing milestones or certain share prices are achieved, the warrants would only be exercisable in conjunction with the sale of the Company or in November 2025 through a cashless exercise.

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 arrangement is unknown to the beneficiary as the arrangement is a silent trust. The Company recognizes the warrants as compensation expense within the consolidated statement of operations and comprehensive loss 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 December 31, 2021 and 2020, 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 $1,070 and $695 as of December 31, 2021 and 2020, respectively, and was recorded as stock compensation expense within research and development expense and a credit to stockholders’ equity in the consolidated financial statements.

Stock Options, Restricted Stock and Stock-based Compensation

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock options, restricted stock and stock—based compensation

10. Stock options, restricted stock and stock—based compensation

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 December 31, 2021, there will be no additional 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, or 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. There are 2,054,000 shares of common stock reserved for issuance under the 2021 Plan and 1,878,997 shares remained available for grant as of December 31, 2021. 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 January 1, 2020		928,286		$	1.43		3.51	$	120
Granted		3,221,378			1.55		3.83		10,997
Exercised		(21,359	)		1.46
Cancelled or forfeited		(114,994	)		1.46
Outstanding as of December 31, 2020		4,013,311		$	1.52		4.45	$	13,818
Granted		808,711			6.34		9.34		1,194
Exercised		(24,410	)		1.46
Cancelled or forfeited		(14,279	)		1.55		-		-
Outstanding as of December 31, 2021		4,783,333		$	2.34		8.51	$	26,393
Exercisable as of December 31, 2021		2,052,111		$	1.84		8.18	$	12,272
Unvested as of December 31, 2021		2,731,222		$	2.72		8.76	$	14,121

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:


	YEAR ENDED DECEMBER 31,
	2021			2020
Expected option life (years)	5.00 - 10.00			5.00 - 10.00
Risk-free interest rate	0.89% - 1.35%			0.45% - 0.92%
Expected volatility	83.80% - 89.02%			74.86% - 89.07%
Expected dividend yield		0	%		0	%
Exercise price	$4.97 - $11.23			$1.55-$1.55
Fair value of common stock	$4.97 - $11.23			$1.55 - $4.97

The total intrinsic value of stock options vested during the years ended December 31, 2021 and 2020 was $6,648 and $12, respectively.

Stock-based compensation expense for the years ended December 31, 2021 and 2020 was classified in the consolidated statements of operations and comprehensive loss as follows:


	YEAR ENDED DECEMBER 31,
	2021		2020
Research and development	$	1,226	$	847
General and administrative		1,737		1,260
Total stock based compensation expense	$	2,963	$	2,107

As of December 31, 2021 and 2020, total unrecognized compensation cost related to the unvested stock-based awards was $6,298 and $4,778, respectively. These amounts are expected to be recognized over a weighted average period of 2.26 and 3.05 years, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

11. Income taxes

Income tax expense for 2021 and 2020 consists of the following:


	YEAR ENDED DECEMBER 31,
	2021		2020
Current expense (benefit):
Federal	$	—	$	—
State		—		—
Total current expense (benefit):		—		—
Deferred expense (benefit):
Federal		—		—
State		—		—
Total deferred expense (benefit):		—		—
Total income tax expense (benefit):	$	—	$	—

A reconciliation of income tax expense at the federal statutory income tax rate to the income tax expense at the Company’s effective income tax rate is as follows:


	YEAR ENDED DECEMBER 31,
	2021			2020
Income at US statutory rate		21.00	%		21.00	%
Permanent adjustments		(0.59	)%		(1.07	)%
Mark to market		(6.64	)%		(5.47	)%
State taxes, net of federal benefit		4.01	%		6.65	%
Valuation allowance		(19.86	)%		(23.95	)%
Tax credits		2.08	%		2.84	%
		—			—

Net deferred tax assets as of December 31, 2021 and 2020 consist of the following:


	YEAR ENDED DECEMBER 31,
	2021			2020
Net operating losses	$	13,892		$	7,934
Intangibles		654			750
Accrued expenses & other		243			346
Deferred revenue		34			68
Stock Compensation		820			431
Credits		2,850			1,789
Total deferred tax assets		18,493			11,318
Valuation allowance		(18,493	)		(11,318	)
Net deferred tax assets (liability)	$	—		$	—

As of December 31, 2021, the Company has gross federal and state net operating loss carryforwards of approximately $8,815 and $48,363 which begin to expire in 2027 and 2032, respectively. Additionally, the Company has $42,780 of the federal net operating loss carryforwards that can be carried forward indefinitely.

As of December 31, 2021, the Company has gross federal and state tax credit carryforwards of approximately $1,950 and $1,139, respectively, which begin to expire in 2036 and 2028, respectively.

Management of the Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are comprised principally of net operating loss carryforwards and certain tax credits. Management has considered the Company’s history of cumulative net losses incurred since inception, as well as its lack of product revenue since inception, and has determined that it is more likely than not that the Company will not realize the benefits of its deferred tax assets. As a result, a full valuation allowance has been established at December 31, 2021 and 2020.

Section 382 of the Internal Revenue Code of 1986, as amended (“Section 382”), contains rules that limit the ability of a company that undergoes in ownership change to utilize its net operating losses (“NOLs”) and tax credits existing as of the date of such ownership change. Under the rules, such an ownership change is generally any change in ownership of more than 50% of a company’s stock within a rolling three-year period. The rules generally operate by focusing on changes in ownership of all stock considered by the rules as owning, directly or indirectly, 5% or more of the stock of a company and any change in ownership arising from new issuances of stock by the company. The Company has not yet determined if such a limitation would be placed against its available net operating losses. The Company will make such a determination prior to the utilization of any future net operating losses.

A summary of changes in the valuation allowance for deferred tax assets during the year ended December 31, 2021 and 2020 were as follows:


	YEAR ENDED DECEMBER 31,
	2021		2020
Valuation allowance	$	11,318	$	7,089
Increases recorded to income tax provision		7,175		4,248
Decreases recorded to income tax provision		—		(19	)
Valuation allowance	$	18,493	$	11,318

The Company files income tax returns in the United States and various state and local jurisdictions. The federal and state tax returns are generally subject to examination for the years ended December 31, 2014 through December 31, 2021. There are currently no pending tax examinations. To the extent the Company has tax attribute carryforwards, the tax year in which the attribute was generated may still be adjusted upon examination.

- 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI http://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Exclusive Licensing Agreement with a Related Party

12 Months Ended

Dec. 31, 2021

License Agreement [Abstract]

Exclusive Licensing Agreement with a Related Party

12. 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. Ventagen paid the Company $1,000 upon the signing of the agreement and agreed to a fixed future payment to the Company of $2,500. The future payment will be made upon the achievement of $5,000 of sales of an approved product by Ventagen and is subject to reduction if Ventagen’s costs to develop an approved product exceeds $4,000. 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 senior executives and significant stockholders of the Company, and trusts for the benefit of their children.

The Company is recognizing the $1,000 upfront license fee as research and development service revenue, related party, as the Company’s license agreement with Ventagen is within the scope of ASC 606. The license agreement met the contract existence criteria and contained distinct, identifiable performance obligations for which the stand-alone selling prices were readily determinable and allocable. The terms of the agreement contained multiple, distinct performance obligations, including transfer of a license for the territory, research and development oversight for the trials run by Ventagen, and clinical data sharing.

The Company estimated the transaction prices, including any variable consideration, at contract inception and determined the fair value of such obligations. The performance obligation associated with the license transfer was satisfied at a point in time, or at contract inception; however, the Company assigned no value to the license transfer. The remaining $1,000 transaction price was allocated between the research and development oversight and clinical data sharing. The Company is recognizing revenue for these obligations over an 8-year period, beginning in 2015, by measuring the progress towards satisfaction of the performance obligations. As clinical oversight and clinical data sharing occurs over the 8—year clinical trial period, the revenue is recognized over the same period in which the cost for these services is incurred.

The Company defers recognition of the portion of the $1,000 non-refundable upfront license fee for the portion of the performance obligations that are not satisfied. The Company recognized revenue of $125 in the years ended December 31, 2021 and 2020. The license agreement includes a $2,500 potential future milestone payment due to the Company upon successful completion of certain separate, distinct events. At this time, the Company cannot estimate when the milestone-related performance obligations are expected to be achieved and will recognize revenue once

satisfaction is probable. There was no additional variable consideration, significant financing components, noncash consideration, or consideration payable to the customer in this agreement.

Technology License Agreement

12 Months Ended

Dec. 31, 2021

Technology License Agreement [Abstract]

Technology License Agreement

13. 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 $750 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 to MGB to be applied toward the Company’s on-going obligations to reimburse patent expenses. In the years ended December 31, 2021 and 2020, respectively, the Company expensed $28 and $269, respectively, for 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 $100 and agreed to reimburse patent costs incurred by MGB, including $141 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 beginning following the fourth anniversary of the effective date. The MGB License contains cumulative milestone payments equaling a maximum amount of $39,000 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 is also agreed to pay a single digit royalty rate on net sales of any derived products.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

14. Commitments and contingencies

Related party leases

In January 2008, the Company entered into an operating lease agreement with a term through December 31, 2022 with Ellka Holdings, LLC (“Ellka”) for the space in which the Company operated in Auburndale, MA. This lease was terminated and a termination payment of $115 was made to Ellka and included in operating expenses for the year ended December 31, 2020. In May 2016, the Company entered into a second lease agreement with Ellka for living space for employees, also in Auburndale, MA which was also was terminated at the end of 2020. Ellka is owned and operated by the company’s founders, who were senior executives and are significant stockholders of the Company, and members of their immediate family.

Facility 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 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 cost of this construction was $765 and was paid for by the landlord provided allowance in the lease agreement. The $765 lease incentive was recorded as deferred rent and is being amortized over the life of the lease.

Total rent expense under these leases was $459 and $619 for the years ended December 31, 2021 and 2020, respectively.

The future minimum lease payments at December 31, 2021, are as follows:


2022	$	567
2023		583
2024		598
2025		613
Thereafter		415
Total minimum lease payments	$	2,776

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 seven – year 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 December 31, 2021, 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

The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities.

Net Loss Per Share

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net loss per share

15. Net loss per share

Net loss per share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	YEAR ENDED DECEMBER 31,
	2021			2020
Numerator:
Net loss attributable to common stockholders	$	(36,124	)	$	(17,680	)
Denominator:
Weighted-average shares of common stock outstanding-basic and diluted		18,873,048			11,615,208
Net loss per share attributed to common stockholders-basic and diluted	$	(1.91	)	$	(1.52	)

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 attributable to common stockholders is the same.

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.


	YEAR ENDED DECEMBER 31,
	2021		2020
Series B Preferred (as converted to common stock)		—		4,538,592
Series C Preferred (as converted to common stock)		—		2,454,196
Outstanding warrants for common stock		7,507,708		7,632,518
Outstanding stock options (as converted to common stock)		4,783,333		4,013,311
		12,291,041		18,638,617

Subsequent Events

12 Months Ended

Dec. 31, 2021

Subsequent Events [Abstract]

Subsequent events

16. Subsequent events

On February 24, 2022, the Company entered into a loan and security agreement (the “Loan Agreement”) with a bank pursuant to which the bank 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 can borrow up to an additional aggregate principal amount not to exceed $5.0 million, at any time on or prior to December 31, 2022, following the Company having provided evidence to the bank of (a) achievement of 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 term loans are 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. 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 prepayment.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Basis of presentation

issued by the FASB in these notes to the financial statements are to the FASB Accounting Standards Codification (ASC).

Principles of consolidation

Segment Information

Emerging growth company

Use of estimates

Comprehensive income (loss)

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

Concentration of credit risk

Concentrations of credit risk

Impairment of long lived assets

Impairment of long-lived assets

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.

Revenue recognition

Research and development costs and accruals

Patent costs

Stock-based compensation

Government grants

Income taxes

Net loss per share

effect is anti-dilutive. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2021 and 2020.

Recently adopted and issued accounting standards

Recently adopted accounting standards

Recently issued accounting standards

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

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

Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

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


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2021 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Long-term debt	$	—	$	—	$	560	$	560
Warrant liability		—		—		18,252		18,252
Total	$	—	$	—	$	18,812	$	18,812


	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2020 USING:
	LEVEL 1		LEVEL 2		LEVEL 3		TOTAL
Liabilities:
Long-term debt	$	—	$	—	$	483	$	483
Warrant liability		—		—		6,831		6,831
Total	$	—	$	—	$	7,314	$	7,314

Schedule of Aggregate Fair Values of 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 liabilities, for which fair value is determined by Level 3 inputs:


	SERIES B WARRANT LIABILITY		PROMISSORY NOTE
Balance at January 1, 2020	$	2,226	$	420
Change in fair value		4,605		63
Balance at December 31, 2020	$	6,831	$	483
Change in fair value		11,421		77
Balance at December 31, 2021	$	18,252	$	560

Fixed Assets, Net (Tables)

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Summary of Fixed Assets, Net

Fixed assets, net consisted of the following:


	DECEMBER 31,
	2021			2020
Construction in progress	$	—		$	1,216
Laboratory equipment		77			24
Manufacturing equipment		933			1,213
Furniture and fixtures		112			112
Networking and computer equipment		72			47
Leasehold improvements		2,994			309
Total fixed assets	$	4,188		$	2,921
Less accumulated depreciation		(352	)		(134	)
Fixed assets, net	$	3,836		$	2,787

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following:


	DECEMBER 31,
	2021		2020
Payroll and employee related expenses	$	2,096	$	1,198
Third-party research and development expenses		632		1,299
Professional fees and other		710		645
	$	3,438	$	3,142

Capital Stock (Tables)

12 Months Ended

Dec. 31, 2021

Capital Stock [Abstract]

Schedule of Common Stock Reserved For Future Issuance

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


	DECEMBER 31,
	2021		2020
Series B Preferred conversion		—		4,538,592
Series C Preferred conversion		—		2,454,196
Stock options outstanding		4,783,333		4,013,311
Shares available for future grant under stock option plan		1,878,997		87,042
Warrants		7,507,708		7,632,518
		14,170,038		18,725,659

Warrants (Tables)

12 Months Ended

Dec. 31, 2021

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 December 31, 2021:


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

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

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Option Activity


	NUMBER OF STOCK OPTIONS			WEIGHTED- AVERAGE EXERCISE PRICE		WEIGHTED- AVERAGE REMAINING CONTRACTUAL TERM (IN YEARS)		AGGREGATE INTRINSIC VALUE
Outstanding as of January 1, 2020		928,286		$	1.43		3.51	$	120
Granted		3,221,378			1.55		3.83		10,997
Exercised		(21,359	)		1.46
Cancelled or forfeited		(114,994	)		1.46
Outstanding as of December 31, 2020		4,013,311		$	1.52		4.45	$	13,818
Granted		808,711			6.34		9.34		1,194
Exercised		(24,410	)		1.46
Cancelled or forfeited		(14,279	)		1.55		-		-
Outstanding as of December 31, 2021		4,783,333		$	2.34		8.51	$	26,393
Exercisable as of December 31, 2021		2,052,111		$	1.84		8.18	$	12,272
Unvested as of December 31, 2021		2,731,222		$	2.72		8.76	$	14,121

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:


	YEAR ENDED DECEMBER 31,
	2021			2020
Expected option life (years)	5.00 - 10.00			5.00 - 10.00
Risk-free interest rate	0.89% - 1.35%			0.45% - 0.92%
Expected volatility	83.80% - 89.02%			74.86% - 89.07%
Expected dividend yield		0	%		0	%
Exercise price	$4.97 - $11.23			$1.55-$1.55
Fair value of common stock	$4.97 - $11.23			$1.55 - $4.97

Schedule of Stock-based Compensation Expense

Stock-based compensation expense for the years ended December 31, 2021 and 2020 was classified in the consolidated statements of operations and comprehensive loss as follows:


	YEAR ENDED DECEMBER 31,
	2021		2020
Research and development	$	1,226	$	847
General and administrative		1,737		1,260
Total stock based compensation expense	$	2,963	$	2,107

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

Income tax expense for 2021 and 2020 consists of the following:


	YEAR ENDED DECEMBER 31,
	2021		2020
Current expense (benefit):
Federal	$	—	$	—
State		—		—
Total current expense (benefit):		—		—
Deferred expense (benefit):
Federal		—		—
State		—		—
Total deferred expense (benefit):		—		—
Total income tax expense (benefit):	$	—	$	—

Reconciliation of Income Tax Expense

A reconciliation of income tax expense at the federal statutory income tax rate to the income tax expense at the Company’s effective income tax rate is as follows:


	YEAR ENDED DECEMBER 31,
	2021			2020
Income at US statutory rate		21.00	%		21.00	%
Permanent adjustments		(0.59	)%		(1.07	)%
Mark to market		(6.64	)%		(5.47	)%
State taxes, net of federal benefit		4.01	%		6.65	%
Valuation allowance		(19.86	)%		(23.95	)%
Tax credits		2.08	%		2.84	%
		—			—

Schedule of Net Deferred Tax Assets

Net deferred tax assets as of December 31, 2021 and 2020 consist of the following:


	YEAR ENDED DECEMBER 31,
	2021			2020
Net operating losses	$	13,892		$	7,934
Intangibles		654			750
Accrued expenses & other		243			346
Deferred revenue		34			68
Stock Compensation		820			431
Credits		2,850			1,789
Total deferred tax assets		18,493			11,318
Valuation allowance		(18,493	)		(11,318	)
Net deferred tax assets (liability)	$	—		$	—

Summary of Changes in Valuation Allowance for Deferred Tax Assets

A summary of changes in the valuation allowance for deferred tax assets during the year ended December 31, 2021 and 2020 were as follows:


	YEAR ENDED DECEMBER 31,
	2021		2020
Valuation allowance	$	11,318	$	7,089
Increases recorded to income tax provision		7,175		4,248
Decreases recorded to income tax provision		—		(19	)
Valuation allowance	$	18,493	$	11,318

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Payments

The future minimum lease payments at December 31, 2021, are as follows:


2022	$	567
2023		583
2024		598
2025		613
Thereafter		415
Total minimum lease payments	$	2,776

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:


	YEAR ENDED DECEMBER 31,
	2021			2020
Numerator:
Net loss attributable to common stockholders	$	(36,124	)	$	(17,680	)
Denominator:
Weighted-average shares of common stock outstanding-basic and diluted		18,873,048			11,615,208
Net loss per share attributed to common stockholders-basic and diluted	$	(1.91	)	$	(1.52	)

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


	YEAR ENDED DECEMBER 31,
	2021		2020
Series B Preferred (as converted to common stock)		—		4,538,592
Series C Preferred (as converted to common stock)		—		2,454,196
Outstanding warrants for common stock		7,507,708		7,632,518
Outstanding stock options (as converted to common stock)		4,783,333		4,013,311
		12,291,041		18,638,617

Organization and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Jul. 29, 2021 USD ($) $ / shares shares	Jul. 14, 2021	Dec. 31, 2021 USD ($) Candidate $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Aug. 13, 2021 $ / shares shares
Organization And Basis Of Presentation [Line Items]
Number of product candidates \| Candidate			2
Net loss \| $			$ (36,124)	$ (17,680)
Accumulated deficit \| $			$ (80,295)	$ (44,171)
Common stock, shares, issued			28,689,842	11,635,094
Common stock par value \| $ / shares			$ 0.01	$ 0.01
Reverse stock split		one-for-2.4579
Stock split conversion ratio		0.407
IPO
Organization And Basis Of Presentation [Line Items]
Common stock, shares, issued	9,000,000
Common stock par value \| $ / shares	$ 8.00
Net proceeds \| $	$ 71,335
Convertible preferred stock converted into common stock	7,066,398
Underwriters’ Overallotment Option
Organization And Basis Of Presentation [Line Items]
Common stock, shares, issued					887,994
Common stock par value \| $ / shares					$ 8.00

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segment \| Segment		1
Cash and cash equivalent maturity period		90 days
Restricted cash	$ 424,000	$ 424,000	$ 266,000
Long-lived assets, impairment charge	553,000
Expected dividend assumed		$ 0
Percentage income taxes benefits upon ultimate settlement		50.00%
Expected right of use asset	1,300,000	$ 1,300,000
Expected lease liability	$ 2,400,000	$ 2,400,000
ASU 2019-12
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2021	Jan. 01, 2021
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true	true
Govenment
Significant Accounting Policies [Line Items]
Grants receivable	$ 1,076,000	$ 1,076,000	$ 624,000
Minimum
Significant Accounting Policies [Line Items]
Marketable debt securities maturities duration		90 days

Summary of Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
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
Leasehold Improvements
Significant Accounting Policies [Line Items]
Estimated Useful Life	Shorter of the useful life or remaining lease term

Fair Value of Financial Assets and Liabilities - Schedule of Information About Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Liabilities:
Long-term debt	$ 560	$ 483
Fair Value, Recurring
Liabilities:
Long-term debt	560	483
Warrant liability	18,252	6,831
Total	18,812	7,314
Level 3 \| Fair Value, Recurring
Liabilities:
Long-term debt	560	483
Warrant liability	18,252	6,831
Total	$ 18,812	$ 7,314

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References + Details

Fair Value of Financial Assets and Liabilities - Additional Information (Details) - Fair Value, Recurring - Level 3 - Unsecured Note	12 Months Ended
	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term debt, due month and year	2027-11
Debt instrument, credit rating	CCC
Measurement Input, Credit Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term debt, measurement input	15.83

Fair Value of Financial Assets and Liabilities - Schedule of Aggregate Fair Values of Liabilities, for Which Fair Value Determined by Level 3 Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Promissory Note
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance	$ 483	$ 420
Change in fair value	77	63
Balance	560	483
Series B Warrant Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance	6,831	2,226
Change in fair value	11,421	4,605
Balance	$ 18,252	$ 6,831

Fixed Assets, Net - Summary of Fixed Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total fixed assets	$ 4,188	$ 2,921
Less accumulated depreciation	(352)	(134)
Fixed assets, net	3,836	2,787
Construction in Progress
Property Plant And Equipment [Line Items]
Total fixed assets		1,216
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	77	24
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	933	1,213
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total fixed assets	112	112
Networking and Computer Equipment
Property Plant And Equipment [Line Items]
Total fixed assets	72	47
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total fixed assets	$ 2,994	$ 309

Fixed Assets, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 232	$ 91

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Payroll and employee related expenses	$ 2,096	$ 1,198
Third-party research and development expenses	632	1,299
Professional fees and other	710	645
Accrued expenses	$ 3,438	$ 3,142

Borrowings under Paycheck Protection Program - Additional Information (Details) - Paycheck Protection Program, CARES Act - USD ($) $ in Thousands		1 Months Ended
	Apr. 28, 2020	Apr. 30, 2021
Debt Instrument [Line Items]
Unsecured loan	$ 460
Fixed annual rate	1.00%
Loan forgiveness		$ 460
Loan, maturity period	2 years

Long-Term Debt - Additional Information (Details) - Periphagen, Inc. - USD ($) $ in Thousands		12 Months Ended
	Dec. 09, 2019	Dec. 31, 2021
Debt Instrument [Line Items]
Asset acquisition, assumption of promissory note	$ 1,000
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	$ 417	$ 560

Capital Stock - Additional Information (Details) - USD ($)					12 Months Ended
	Jul. 29, 2021	Jul. 14, 2021	Mar. 13, 2019	Nov. 13, 2018	Dec. 31, 2021	Dec. 31, 2020	Nov. 30, 2018
Capital Stock [Line Items]
Temporary equity, shares authorized						17,187,676
Conversion of convertible preferred stock to common stock					7,066,398
Preferred stock, shares authorized					10,000,000
Preferred stock, shares issued					0
Preferred stock par value					$ 0.01	$ 0.01
Common stock, shares authorized					150,000,000	75,000,000
Common stock, par value					$ 0.01	$ 0.01
Common stock, shares, issued					28,689,842	11,635,094
Common stock, shares, outstanding					28,689,842	11,635,094
Reverse stock split		one-for-2.4579
IPO including Underwriters' Option
Capital Stock [Line Items]
Common stock, par value	$ 8.00
Common stock, shares, issued	9,887,994
IPO
Capital Stock [Line Items]
Common stock, par value	$ 8.00
Common stock, shares, issued	9,000,000
Net proceeds after deducting underwriting discounts and commissions and offering expenses	$ 71,335,000
Convertible preferred stock converted into common stock	7,066,398
Minimum
Capital Stock [Line Items]
Conversion into common stock upon the closing of the sale of shares of common stock to the public					$ 25,000,000
Series B Convertible Preferred Stock
Capital Stock [Line Items]
Temporary equity, shares authorized					0	11,155,506
Preferred stock, shares authorized				11,155,506
Preferred stock, shares issued				9,026,618
Preferred stock par value				$ 0.01
Purchase price per share				$ 2.7696
Gross proceeds from issuance of convertible preferred stock				$ 25,000,000
Class of warrants issued per share				$ 6.81
Preferred shares issued as payment of convertible notes							1,751,658
Preferred shares issued as partial repayment of outstanding related party notes payable.							377,130
Series B Convertible Preferred Stock \| Maximum
Capital Stock [Line Items]
Class of warrants issued				7,344,982
Series C Convertible Preferred Stock
Capital Stock [Line Items]
Temporary equity, shares authorized					0	6,032,170
Preferred stock, shares issued			6,032,170
Preferred stock par value			$ 0.01
Purchase price per share			$ 3.73
Gross proceeds from issuance of convertible preferred stock			$ 22,500,000

Capital Stock - Schedule of Common Stock Reserved For Future Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Capital Stock [Line Items]
Common stock reserved for future issuance	14,170,038	18,725,659
Series B Convertible Preferred Stock
Capital Stock [Line Items]
Common stock reserved for future issuance		4,538,592
Series C Convertible Preferred Stock
Capital Stock [Line Items]
Common stock reserved for future issuance		2,454,196
Stock Options Outstanding
Capital Stock [Line Items]
Common stock reserved for future issuance	4,783,333	4,013,311
Shares Available for Future Grant Under Stock Option Plan
Capital Stock [Line Items]
Common stock reserved for future issuance	1,878,997	87,042
Warrants
Capital Stock [Line Items]
Common stock reserved for future issuance	7,507,708	7,632,518

Warrants - Summary of Warrants Outstanding for Purchase of Common Stock (Details) - $ / shares		12 Months Ended
	Jun. 24, 2021	Dec. 31, 2021	Dec. 31, 2020	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
EXPIRATION DATES	2023-11	2025-11
Series B Conditional Warrants
Class Of Warrant Or Right [Line Items]
SHARES OF COMMON STOCK SUBJECT TO WARRANTS		3,672,484
EXERCISE PRICE PER SHARE		$ 6.81
EXPIRATION DATES	2023-11	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
EXPIRATION DATES		2029-03

Warrants - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jun. 24, 2021	Mar. 20, 2019	Dec. 31, 2021	Dec. 31, 2020	Nov. 13, 2018
Class Of Warrant Or Right [Line Items]
Fair value of warrant liability			$ 18,252	$ 6,831
Common stock, par value			$ 0.01	$ 0.01
Series B Warrants
Class Of Warrant Or Right [Line Items]
Class of warrant or right issued					3,672,484
Class of warrant or right period			5 years
Class of warrants issued per share			$ 6.81		$ 6.81
Expiration dates	2023-11		2025-11
Estimated fair value of warrants			$ 2,124
Extended expiration dates	2025-11
Class of warrants issued			3,672,484		3,672,484
Series B Conditional Warrants
Class Of Warrant Or Right [Line Items]
Class of warrants issued per share			$ 6.81
Expiration dates	2023-11		2025-11
Fair value of warrant liability			$ 18,252	$ 6,831
Extended expiration dates	2025-11
Class of warrants issued			3,672,484
NC Ohio Trust
Class Of Warrant Or Right [Line Items]
Class of warrants issued per share		$ 1.46	$ 1.46
Expiration dates			2029-03
Class of warrants issued		162,740	162,740	162,740
Common stock, par value		$ 0.01
Warrant liability			$ 1,070	$ 695
NC Ohio Trust \| Minimum
Class Of Warrant Or Right [Line Items]
Past services provided by beneficiary		15 years

Stock Options, Restricted Stock and Stock-based Compensation - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jul. 14, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	14,170,038	18,725,659
Number of shares available for grant	1,878,997
Intrinsic value of stock options vested	$ 6,648	$ 12
Unrecognized compensation cost related to unvested stock options	$ 6,298	$ 4,778
Stock-based awards are expected to be recognized over a weighted average period	2 years 3 months 3 days	3 years 18 days
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 awards under plan	0
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance			2,054,000

Stock Options, Restricted Stock and Stock-based Compensation - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number Of Stock Options, Shares Outstanding	4,013,311	928,286
Number Of Stock Options, Shares, Granted	808,711	3,221,378
Number Of Stock Options, Shares, Exercised	(24,410)	(21,359)
Number Of Stock Options, Shares, Cancelled or forfeited	(14,279)	(114,994)
Number Of Stock Options, Shares Outstanding	4,783,333	4,013,311	928,286
Exercisable as of December 31, 2021	2,052,111
Unvested as of December 31, 2021	2,731,222
Weighted-Average Exercise Price, Outstanding	$ 1.52	$ 1.43
Weighted-Average Exercise Price, Granted	6.34	1.55
Weighted-Average Exercise Price, Exercised	1.46	1.46
Weighted-Average Exercise Price, Cancelled or forfeited	1.55	1.46
Weighted-Average Exercise Price, Outstanding	2.34	$ 1.52	$ 1.43
Exercisable as of December 31, 2021	1.84
Unvested as of December 31, 2021	$ 2.72
Weighted- Average Remaining Contractual Term (In Years), Outstanding	8 years 6 months 3 days	4 years 5 months 12 days	3 years 6 months 3 days
Weighted- Average Remaining Contractual Term (In Years), Granted	9 years 4 months 2 days	3 years 9 months 29 days
Exercisable as of December 31, 2021	8 years 2 months 4 days
Unvested as of December 31, 2021	8 years 9 months 3 days
Aggregate Intrinsic Value, Outstanding	$ 26,393	$ 13,818	$ 120
Aggregate Intrinsic Value, Granted	1,194	$ 10,997
Exercisable as of December 31, 2021	12,272
Unvested as of December 31, 2021	$ 14,121

Stock Options, Restricted Stock and Stock-based Compensation - Schedule of Fair Value of Stock Options Granted Was Estimated on Black-Scholes Options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
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 years
Risk-free interest rate	0.89%	0.45%
Expected volatility	83.80%	74.86%
Exercise price	$ 4.97	$ 1.55
Fair value of common stock	$ 4,970	$ 1,550
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected option life (years)	10 years	10 years
Risk-free interest rate	1.35%	0.92%
Expected volatility	89.02%	89.07%
Exercise price	$ 11.23	$ 1.55
Fair value of common stock	$ 11,230	$ 4,970

Stock Options, Restricted Stock and Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	$ 2,963	$ 2,107
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	1,226	847
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock based compensation expense	$ 1,737	$ 1,260

Income Taxes - Reconciliation of Income Tax Expense (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income at US statutory rate	21.00%	21.00%
Permanent adjustments	(0.59%)	(1.07%)
Mark to market	(6.64%)	(5.47%)
State taxes, net of federal benefit	4.01%	6.65%
Valuation allowance	(19.86%)	(23.95%)
Tax credits	2.08%	2.84%
Effective income tax rate	0.00%	0.00%

Income Taxes - Schedule of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Net operating losses	$ 13,892	$ 7,934
Intangibles	654	750
Accrued expenses & other	243	346
Deferred revenue	34	68
Stock Compensation	820	431
Credits	2,850	1,789
Total deferred tax assets	18,493	11,318
Valuation allowance	(18,493)	(11,318)	$ (7,089)
Net deferred tax assets (liability)	$ 0	$ 0

Income Taxes - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Income Taxes [Line Items]
Income tax examination, description	The federal and state tax returns are generally subject to examination for the years ended December 31, 2014 through December 31, 2021. There are currently no pending tax examinations.
Federal
Income Taxes [Line Items]
Operating loss carryforwards	$ 8,815
Operating loss carryforwards indefinite	$ 42,780
Operating loss carryforwards, begin to expire year	2027
Tax credit carryforward	$ 1,950
Tax credit carryforward, begin to expire year	2036
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 48,363
Operating loss carryforwards, begin to expire year	2032
Tax credit carryforward	$ 1,139
Tax credit carryforward, begin to expire year	2028

Income Taxes - Summary of Changes in Valuation Allowance for Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Valuation allowance	$ 11,318	$ 7,089
Increases recorded to income tax provision	7,175	4,248
Decreases recorded to income tax provision		(19)
Valuation allowance	$ 18,493	$ 11,318

Exclusive Licensing Agreement with a Related Party - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2021	Dec. 31, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development service revenue, related party		$ 125,000	$ 125,000
Exclusive Licensing Agreement \| Ventagen
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment from related party	$ 1,000,000
Due from related parties	2,500,000
Future payment made upon the achievement of sales	5,000,000
Related party costs	$ 4,000,000
Commercial purposes at a price of cost plus percentage	25.00%
Related party transactions, ownership percentage	49.50%
Licensing agreement clinical trial period	8 years
Potential future milestone payment		2,500,000	2,500,000
Additional variable consideration amount payable to customer		$ 0	$ 0
Exclusive Licensing Agreement \| Ventagen \| ASC 606
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront license fee	$ 1,000,000
Exclusive Licensing Agreement \| Ventagen \| Founders
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Related party transactions, ownership percentage	47.00%

Exclusive Licensing Agreement with a Related Party - Additional Information (Details 1) - Exclusive Licensing Agreement - Ventagen - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2014-04-01 $ in Thousands	Mar. 31, 2014 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue, remaining performance obligation, amount	$ 1,000
Revenue, remaining performance obligation, expected timing of satisfaction, period	8 years

Technology License Agreement - Additional Information (Details) - BWH License - USD ($) $ in Thousands			12 Months Ended
	Sep. 15, 2020	Jan. 20, 2018	Dec. 31, 2021	Dec. 31, 2020
Technology License Agreement [Line Items]
Committed amount to remitting in support of clinical trial		$ 750
Committed period to remitting in support of clinical trial		3 years
Non-refundable fee		$ 40
Expense for startup and patient fees for clinical trials			$ 28	$ 269
Payment for license fee	$ 100
Payment at the time of entering into license	141
Payment for annual license fee	50
Maximum amount upon achievement of various clinical, commercial and sales milestones	$ 39,000

Commitments and Contingencies - Additional Information (Details)		12 Months Ended
	Feb. 04, 2019 USD ($) ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Rent expense		$ 459,000	$ 619,000
Noncancelable operating lease term		7 years
Office space noncancelable operating lease expiration date		2026
Loss related to indemnification obligations		$ 0
Corporate, Clinical and Manufacturing Operations \| Massachusetts
Commitments And Contingencies Disclosure [Line Items]
Area of lease property \| ft²	15,197
Lease expiration date	Aug. 31, 2026
Property modification cost paid by landlord	$ 765,000
Deferred rent	$ 765,000
Ellka Holdings, LLC
Commitments And Contingencies Disclosure [Line Items]
Lease termination payment			$ 115,000

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022	$ 567
2023	583
2024	598
2025	613
Thereafter	415
Total minimum lease payments	$ 2,776

Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (36,124)	$ (17,680)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	18,873,048	11,615,208
Net loss per share attributable to common stockholders, basic and diluted	$ (1.91)	$ (1.52)

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Net Loss Per Share - Schedule of Potential Shares of Common Stock Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share	12,291,041	18,638,617
Series B Preferred (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		4,538,592
Series C Preferred (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		2,454,196
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	7,632,518
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	4,783,333	4,013,311

Subsequent events - Additional Information (Details)	Dec. 30, 2022 USD ($)	Feb. 24, 2022 USD ($) Installment
Subsequent Event [Line Items]
Loan, maximum borrowing capacity	$ 5,000,000.0
Cash proceeds amount equal to at least from the issuance and sale of equity securities	$ 75,000,000.0
Loan Agreement
Subsequent Event [Line Items]
Number of consecutive \| Installment		24
Loan Agreement \| Subsequent Event
Subsequent Event [Line Items]
Loan agreement date		Feb. 24, 2022
Loan, maximum borrowing capacity		$ 25,000,000.0
Long-term debt		$ 20,000,000.0
Loan Agreement \| Term Loan \| Subsequent Event
Subsequent Event [Line Items]
Debt instrument, payment		monthly
Debt instrument final payment fee percentage		4.50%
Debt instrument, commencing date		Feb. 01, 2024
Loan Agreement \| Maximum \| Subsequent Event
Subsequent Event [Line Items]
Debt instrument subject to prepayment premium percentage		3.00%
Loan Agreement \| Maximum \| Term Loan \| Subsequent Event
Subsequent Event [Line Items]
Interest rate		5.75%
Loan Agreement \| Minimum \| Subsequent Event
Subsequent Event [Line Items]
Debt instrument subject to prepayment premium percentage		1.00%
Loan Agreement \| Prime Rate \| Minimum \| Term Loan \| Subsequent Event
Subsequent Event [Line Items]
Interest rate		2.50%