IO Biotech (IOBT) 10-K 14 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 09, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--12-31
Entity Registrant Name	IO BIOTECH, INC.
Entity Central Index Key	0001865494
Entity File Number	001-41008
Entity Tax Identification Number	87-0909276
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	Ole Maaløes Vej 3
Entity Address, City or Town	Copenhagen N
Entity Address, Country	DK
Entity Address, Postal Zip Code	DK-2200
City Area Code	+45
Local Phone Number	7070 2980
Title of each class	Common stock, par value $0.001 per share
Trading Symbol(s)	IOBT
Name of each exchange on which registered	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 73.1
Entity Common Stock, Shares Outstanding		28,815,267
Document Annual Report	true
Document Transition Report	false
Documents incorporated by reference	Portions of the registrant’s proxy statement relating to its 2023 Annual Meeting of Stockholders have been incorporated by reference herein in response to Part III, as specifically set forth in Part III.
Auditor Name	EY Godkendt Revisionspartnerselskab
Auditor Firm ID	1757
Auditor Location	Copenhagen, Denmark

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 142,590	$ 211,531
Prepaid expenses and other current assets	5,629	10,207
Total current assets	148,219	221,738
Restricted cash	268	268
Property and equipment, net	741	155
Right of use lease asset	2,493
Other non-current assets	84	127
Total non-current assets	3,586	550
Total assets	151,805	222,288
Current liabilities
Accounts payable	4,004	3,928
Lease liability - current	515
Accrued expenses and other current liabilities	6,157	6,377
Total current liabilities	10,676	10,305
Lease liability - noncurrent	2,275
Other long-term liabilities		59
Total non-current liabilities	2,275	59
Total liabilities	12,951	10,364
Commitments and contingencies (Note 9)
Stockholders' equity
Preferred stock, par value of $0.001 per share; 5,000,000 shares authorized, no shares issued and outstanding as of December 31, 2022 and 2021
Common stock, par value of $0.001 per share; 300,000,000 shares authorized, 28,815,267 shares issued and outstanding as of December 31, 2022 and December 31, 2021, respectively	29	29
Additional paid-in capital	326,705	319,665
Accumulated deficit	(177,739)	(106,281)
Accumulated other comprehensive loss	(10,141)	(1,489)
Total stockholders' equity	138,854	211,924
Total liabilities, convertible preference shares and stockholders' equity	$ 151,805	$ 222,288

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	28,815,267	28,815,267
Common stock, shares outstanding	28,815,267	28,815,267

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses
Research and development	$ 46,986	$ 30,152
General and administrative	24,438	11,082
Total operating expenses	71,424	41,234
Loss from operations	(71,424)	(41,234)
Other income (expense)
Currency exchange gain, net	130	319
Interest income	1,411
Interest expense	(302)	(361)
Fair value adjustments on preference shares tranche obligations		(26,535)
Total other income (expense), net	1,239	(26,577)
Loss before income tax expense	(70,185)	(67,811)
Income tax expense	1,273	68
Net loss	(71,458)	(67,879)
Cumulative dividends on class B and C preference shares		(7,108)
Net loss attributable to common shareholders	$ (71,458)	$ (74,987)
Net loss per common share, basic	$ (2.48)	$ (17.30)
Net loss per common share, diluted	$ (2.48)	$ (17.30)
Weighted-average number of shares used in computing net loss per common share, basic	28,815,267	4,335,629
Weighted-average number of shares used in computing net loss per common share, diluted	28,815,267	4,335,629
Other comprehensive loss
Net loss	$ (71,458)	$ (67,879)
Foreign currency translation	(8,652)	(3,450)
Total comprehensive loss	$ (80,110)	$ (71,329)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preference Shares and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO	Class B Convertible Preference Stock	Class C Convertible Preference Stock	Common Stock	Common Stock IPO	Common Stock Class A Ordinary Shares	Additional Paid-In Capital	Additional Paid-In Capital IPO	Other Comprehensive Loss	Accumulated Deficit
Temporary equity, Balance at Dec. 31, 2020			$ 37,906
Temporary equity, Balance, shares at Dec. 31, 2020			584,583
Balance at Dec. 31, 2020	$ (35,303)						$ 28	$ 1,110		$ 1,961	$ (38,402)
Balance, shares at Dec. 31, 2020							177,200
Temporary equity, Issuance of class C preference shares, net of issuance costs of $340 and adjusted for settlement of tranche obligation of $28,276 of which $25,908 is non-cash				$ 175,509
Temporary equity, Issuance of class C preference shares, net of issuance costs of $340 and adjusted for fair value of tranche obligation of $25,908 at non-cash settlement, shares				1,194,864
Temporary equity, issuance of shares upon conversion of securities			$ (37,906)	$ (175,509)
Temporary equity, issuance of shares upon conversion of securities, shares			(584,583)	(1,194,864)
Exchange of preferred and ordinary shares of IO Biotech ApS into common stock of IO Biotech, Inc.	213,415				$ 21		$ (28)	213,422
Exchange of preferred and ordinary shares of IO Biotech ApS into common stock of IO Biotech, Inc., shares					20,592,413		(177,200)
Issuance of common stock, shares					354	8,222,500
Issuance of common stock		$ 103,350				$ 8			$ 103,342
Equity-based compensation	1,791							1,791
Foreign currency translation	(3,450)									(3,450)
Net loss	(67,879)										(67,879)
Balance at Dec. 31, 2021	211,924				$ 29			319,665		(1,489)	(106,281)
Balance, shares at Dec. 31, 2021					28,815,267
Equity-based compensation	7,040							7,040
Foreign currency translation	(8,652)									(8,652)
Net loss	(71,458)										(71,458)
Balance at Dec. 31, 2022	$ 138,854				$ 29			$ 326,705		$ (10,141)	$ (177,739)
Balance, shares at Dec. 31, 2022					28,815,267

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preference Shares and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Temporary equity, issuance cost	$ 11,765
Class C Convertible Preference Stock
Temporary equity, issuance costs	340
Temporary equity adjusted for settlement of tranche obligation	28,276
Temporary equity adjusted for settlement of tranche obligation non cash portion	$ 25,908

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net loss	$ (71,458)	$ (67,879)
Adjustment to reconcile net loss to net cash used in operating activities
Depreciation	104	2
Equity-based compensation	7,040	1,791
Fair value adjustments preference shares tranche obligations		26,535
Amortization of right of use lease asset	436
Foreign currency gain	(130)	(319)
Provision for deferred tax	87
Changes in operating assets and liabilities
Prepaid expenses and other current assets	4,578	(8,090)
Other noncurrent assets	(44)	(25)
Accounts payable	77	3,406
Lease liability	(139)
Accrued expenses and other current liabilities	(280)	3,933
Net cash used in operating activities	(59,729)	(40,646)
Cash flows from investing activities
Purchase of property and equipment	(690)	(153)
Net cash used in investing activities	(690)	(153)
Cash flows from financing activities
Proceeds from issuance of preference shares		149,941
Proceeds from issuance of common stock		115,115
Net cash provided by financing activities		252,951
Net (decrease) increase in cash, cash equivalents and restricted cash	(60,419)	212,152
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(8,522)	(3,758)
Cash, cash equivalents and restricted cash, beginning of period	211,799	3,405
Cash, cash equivalents and restricted cash, end of period	142,858	211,799
Components of cash, cash equivalents, and restricted cash
Cash and cash equivalents	142,590	211,531
Restricted cash	268	268
Total cash, cash equivalents, and restricted cash	$ 142,858	211,799
Supplemental disclosures of non-cash investing activities:
Exchange of preferred and ordinary shares of IO Biotech ApS into common stock of IO Biotech, Inc. upon closing of initial public offering		213,443
Non-cash portion of settlement of preference shares tranche obligation		25,908
Preferred Stock
Cash flows from financing activities
Issuance costs		(340)
Common Stock
Cash flows from financing activities
Issuance costs		$ (11,765)

Description of Business, Organi

Description of Business, Organization and Liquidity	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Organization and Liquidity	1. Description of Business, Organization and Liquidity Business IO Biotech, Inc. is a clinical-stage biotechnology company dedicated to the identification and development of disruptive immune therapies for the treatment of cancer. As used in these financial statements, unless the context otherwise requires, references to the “Company”, “we,” “us,” and “our” refer to IO Biotech, Inc. and its subsidiaries. IO Biotech ApS was incorporated in Denmark in December 2014. We are developing novel, immune-modulating cancer vaccines based on our T-win technology platform. Corporate reorganization In November 2021, we completed a corporate reorganization whereby IO Biotech ApS became a wholly-owned subsidiary of the Company. In connection with the corporate reorganization, each issued and outstanding Class A ordinary share ($ 0.16 par value) was exchanged on a one for one basis into shares of common stock of the Company ($ 0.001 par value). Each Class B and Class C preference share of IO Biotech ApS was exchanged on a one for one basis into shares of Class B and Class C preferred stock of the Company. Initial Public Offering ("IPO") In November 2021, we completed our IPO, selling an aggregate of 8,222,500 shares of common stock at a price to the public of $ 14.00 per share, including 1,072,500 shares of common stock sold pursuant to the underwriters’ exercise of their option to purchase additional shares of common stock. We received net proceeds from the IPO, after deducting underwriting discounts and commissions and other offering costs, of approximately $ 103.3 million. Immediately prior to the consummation of the IPO, all outstanding shares of our class A ordinary shares and class B and class C convertible preference shares were converted into 20,592,413 shares of common stock. Upon the closing of the IPO on November 9, 2021, a total of 28,815,267 shares of common stock were outstanding. Our common stock began trading on the Nasdaq Global Market on November 5, 2021 under the symbol “IOBT”. On November 9, 2021, we amended and restated the certificate of incorporation of IO Biotech, Inc. to authorize 300,000,000 shares of common stock and 5,000,000 shares of preferred stock. The shares of preferred stock are currently undesignated. Risks and Uncertainties We are subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance reporting capabilities. Our product candidates are in development. There can be no assurance that our research and development will be successfully completed, that adequate protection for our intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if our product development efforts are successful, it is uncertain when, if ever, we will generate significant revenue from product sales. We operate in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, we are dependent upon the services of our employees and consultants. Liquidity Considerations and Going Concern Basis of Accounting Since inception, we have devoted substantially all our efforts to business planning, conducting research and development, recruiting management and technical staff, and raising capital. We have financed our operations primarily through the issuance of convertible preference shares, convertible notes and, most recently, our IPO. Our continued discovery and development of product candidates will require significant additional research and development efforts, including extensive 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 product development efforts are successful, it is uncertain when, if ever, we will realize significant revenue from product sales. As of December 31, 2022, we had an accumulated deficit of $ 177.7 million. We have incurred losses and negative cash flows from operations since inception, including net losses of $ 71.5 million and $ 67.9 million for the years ended December 31, 2022 and 2021, respectively. We expect that our operating losses and negative cash flows will continue for the foreseeable future as we continue to develop our product candidates. We currently expect that our cash and cash equivalents of $ 142.6 million as of December 31, 2022 will be sufficient to fund our operating expenses and capital requirements for at least 12 months from the date the financial statements are issued. On this basis the financial statements are prepared on a going concern basis of accounting. However, additional funding will be necessary to fund future discovery research, pre-clinical and clinical activities. We will seek additional funding through public financings, debt financings, collaboration agreements, strategic alliances and licensing arrangements. Although we have been successful in raising capital in the past, there is no assurance that we will be successful in obtaining such additional financing on acceptable terms, or at all, and we may not be able to enter into collaborations or other arrangements. If we are unable to obtain funding, we could be forced to delay, reduce or eliminate our research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect our business prospects, even our ability to continue operations. Coronavirus Pandemic In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. In order to mitigate the spread of COVID-19, governments have imposed unprecedented restrictions on business operations, travel and gatherings, resulting in a global economic downturn and other adverse economic and societal impacts. The COVID-19 pandemic has also overwhelmed or otherwise led to changes in the operations of many healthcare facilities, including clinical trial sites. We cannot predict the scope and severity of any further disruptions as a result of COVID-19 and continuing resource constraints or their impacts on CROs, us, clinical trial sites and others. But continuing resource constraints or business disruptions for us or any of the third parties with whom we engage, including the collaborators, contract organizations, third-party manufacturers, suppliers, clinical trial sites, regulators and other third parties with whom we conduct business could materially and negatively impact our ability to conduct our business in the manner and on the timelines presently planned. The actual and perceived impact of the COVID-19 pandemic is changing daily, and its ultimate effect on our business cannot be predicted. As a result, there can be no assurance that we will not experience additional negative impacts associated with COVID-19, which could be significant. The COVID-19 pandemic may negatively impact our business, financial condition and results of operations causing interruptions or delays in the Company’s programs and services.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States (U.S. GAAP). Any reference in these notes to applicable guidance is meant to refer to U.S. GAAP, as found in the Accounting Standards Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). Prior to the completion of our IPO, we approved a 3.544 -for-1 stock split of our common stock. All share and per share amounts in the balance sheet and notes thereto have been retroactively adjusted for all periods presented to give effect to this split. Principles of Consolidation The Company’s consolidated financial statements include the accounts of its subsidiaries IO Biotech ApS, IO Bio US, Inc. and IO Biotech Limited. IO Bio US, Inc., a wholly owned subsidiary of IO Biotech ApS, was incorporated in Delaware in May 2021. IO Biotech Limited, a wholly owned subsidiary of IO Biotech ApS, was incorporated in the UK in August 2021. In November 2021, the Company engaged in a series of transactions, referred to collectively as the Corporate Reorganization. As a result of the Corporate Reorganization, IO Biotech ApS became a wholly-owned subsidiary of IO Biotech, Inc. and accordingly, our consolidated financial statements are those of IO Biotech, Inc. for the periods after the date of the Corporate Reorganization. IO Biotech, Inc. is a holding company formed in October 2021, which, prior to our IPO, had nominal assets and no liabilities, contingencies, or commitments, and which has not conducted any operations prior to our IPO other than acquiring the entire issued and outstanding stock of IO Biotech ApS. The Company, IO Biotech ApS, and the holders of all of the issued and outstanding equity interests of IO Biotech ApS have entered into a Share Contribution and Exchange Agreement, dated as of October 29, 2021, pursuant to which the Corporate Reorganization was effected. Management has concluded it has a single reporting segment for purposes of reporting financial condition and results of operations. All intercompany transactions and balances have been eliminated. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect certain reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting periods. Significant items subject to such estimates and assumptions include contract research organization accruals, the fair value of stock-based compensation awards, and valuation of the Company’s deferred tax assets. We base our estimates on historical experience and various other assumptions that we believe to be reasonable under the circumstances. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Currency and Currency Translation The financial statements are presented in U.S. dollars, our reporting currency. The functional currency of IO Biotech ApS and IO Biotech Limited is the Euro. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the functional currency are included in other income and expense in the statements of operations. Assets and liabilities recorded in our Euro functional currency are translated into the U.S. dollar reporting currency at the exchange rate on the balance sheet date. Our expenses in the Euro functional currency are translated into the U.S. dollar reporting currency at the average exchange rate prevailing during the year. Resulting translation adjustments are recorded to other comprehensive income (loss) (OCI). Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value. As of December 31, 2022 and 2021 we had money market funds of $ 88.0 million and $ 101.6 million , respectively, which are included in cash and cash equivalents and reported at fair value (Note 3). Concentrations of Credit Risk and Off-Balance Sheet Risk We maintain our cash in bank deposit and checking accounts that at times exceed insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk, however, we are exposed to the potential loss of uninsured deposits should a financial institution we maintain our cash deposits with fail. Fair Value of Financial Instruments Fair value is defined as the price we would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are as follows: Level 1 —Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 —Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and Level 3 —Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by us in determining fair value is greatest for instruments categorized in Level 3. We monitor the availability of inputs that are significant to the measurement of fair value to assess the appropriate categorization of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances, our policy is to recognize significant transfers between levels at the end of the reporting period. The significance of transfers between levels is evaluated based upon the nature of the financial instrument and size of the transfer relative to total net assets. As of December 31, 2022 and 2021, the Company only held Level 1 financial instruments, respectively. Property and Equipment, net Property and equipment consists of laboratory equipment, computer hardware and office furniture and are recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. The Company estimates useful life on an asset by asset basis, which generally consists of three years for computer hardware, five years for office furniture and five years for laboratory equipment. The Company reviews long-lived assets, such as property and equipment, for impairment when events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. If circumstances require a long-lived asset to be tested for possible impairment, recoverability is measured by comparison of the carrying amount of the assets to estimated future undiscounted cash flows that the assets are expected to generate. If the carrying amount of an asset exceeds its estimated future cash flows, then impairment expense is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. For the years ended December 31, 2022 and 2021 , no impairment expenses were recognized. Research and Development Expenses Research and development costs are expensed as incurred. The Company’s research and development expenses consist primarily of costs incurred for the development of its product candidates and include expenses incurred under agreements with contract manufacturing organizations, or CMOs, contract research organizations, or CROs, investigative sites and consultants to conduct clinical trials and preclinical and non-clinical studies, costs to acquire, develop and manufacture supplies for clinical trials and other studies, salaries and related costs, including equity-based compensation, depreciation and other allocated facility-related and overhead expenses and licensing fees and milestone payments incurred under product license agreements where no alternative future use exists. We may obtain grants from public and private funds for our research and development projects. The grant income for a given period is recognized as a cost reimbursement and is typically based on the time and the costs that we have spent on the specific project during that period. During the years ended December 31, 2022 and 2021, we had active cost reimbursement grants with Innovation Fund Denmark. The grants provided partial reimbursement of employment-related costs related to two employees pursuant to Business Ph.D. and Business post-doctoral programs. For the years ended December 31, 2022 and 2021, research and development expenses in the statements of operations include $ 0.03 million and $ 0.1 million, respectively, of grant income cost reimbursement. We have historically met the requirements to receive a tax credit in Denmark of up to 5.5 million Danish Kroner per year for losses resulting from research and development costs of up to 25.0 million Danish Kroner per year. The tax credit is reported as a reduction to research and development expense in the statements of operations. For the years ended December 31, 2022 and 2021 , research and development expenses include refundable tax credits of $ 0.8 million, respectively. Accrued Research and Development Costs Substantial portions of our pre-clinical and clinical trials are performed by third-party laboratories, medical centers, CMOs, CROs and other vendors. These vendors generally bill monthly for services performed, or bill based upon milestone achievement. For preclinical studies, we accrue expenses based upon estimated percentage of work completed and the contract milestones remaining. For clinical studies, expenses are accrued based upon the number of patients enrolled, the duration of the study and other investigative costs. We monitor patient enrollment, the progress of clinical studies and related activities to the extent possible through internal reviews of data reported to us by the CROs, correspondence with the CROs and clinical site visits. Our estimates depend on the timeliness and accuracy of the data provided by the CROs regarding the status of each program and total program spending. We periodically evaluate the estimates to determine if adjustments are necessary or appropriate based on information we receive. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASC 842”) to enhance the transparency and comparability of financial reporting related to leasing arrangements. Under this new lease standard, most leases are required to be recognized on the balance sheet as right-of-use (ROU) assets and lease liabilities. Disclosure requirements have been enhanced with the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. Prior to January 1, 2019, U.S. GAAP did not require lessees to recognize assets and liabilities related to operating leases on the balance sheet. The new standard establishes a right-of-use model that requires a lessee to recognize a ROU asset and corresponding lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement as well as the reduction of the right of use asset. The Company has adopted the standard effective January 1, 2022 and has chosen to use the effective date as our date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods prior to January 1, 2022. The new standard provides a number of optional practical expedients in transition. The Company has elected to apply the ‘package of practical expedients’ which allow the Company to not reassess (1) whether existing or expired arrangements contain a lease; (2) the lease classification of existing or expired leases; or (3) whether previous initial direct costs would qualify for capitalization under the new lease standard. The Company has also elected to apply (1) the practical expedient which allows us to not separate lease and non-lease components, for new leases entered into after adoption and (2) the short-term lease exemption for all leases with an original term of less than 12 months, for purposes of applying the recognition and measurements requirements in the new standard. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. Operating lease liabilities and their corresponding ROU assets are recorded based on the present value of future lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company will utilize the incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. As of the ASC 842 effective date, the Company’s incremental borrowing rate was approximately 6.5 % based on the remaining lease term of the applicable leases. The Company has elected to combine lease and non-lease components as a single component. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis. Convertible Preference Shares We classified convertible preference shares outside of stockholders’ equity on our balance sheet as certain liquidation events are not strictly within our control. We recorded the issuance of convertible preference shares at the issuance price less related issuance costs. Equity-Based Compensation We account for stock options granted in accordance with ASC 718, Compensation-Stock Compensation . In accordance with ASC 718, compensation expense is measured at the estimated fair value of the stock options at grant date and is included as compensation expense over the vesting period during which an employee provides service in exchange for the award. All share-based awards granted are measured based on the fair value on the date of the grant and compensation expense is recognized with respect to those awards over the requisite service period, which is generally the vesting period of the respective award. The Company reverses any previously recognized compensation cost associated with forfeited awards in the period the forfeiture occurs. Equity-based compensation expense is classified in the Company’s consolidated statements of operations and comprehensive loss in the same manner in which the award recipients’ payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes model. The following summarizes the inputs used: Expected volatility : The Company estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies because we lack company-specific historical and implied volatility information due in part to the limited time in which we have operated as a publicly traded company. We expect to continue to do so until such time as we have adequate historical data regarding the volatility of our traded stock price. Expected term : The expected term of the Company’s stock options has been determined based on the expected time to liquidity. The Company uses the simplified method prescribed by the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term of options granted because we lack company-specific historical and implied expected term information due in part to the limited time in which we have operated as a publicly traded company. Risk-free interest rate : The risk-free interest rate is based on the implied yield on a U.S. Treasury security at a constant maturity with a remaining term equal to the expected term of the option granted. Dividends : Expected dividend yield is zero because the Company does not pay cash dividends on common shares and does not expect to pay any cash dividends in the foreseeable future. Prior to the Company's IPO, valuations were updated when facts and circumstances indicated that the most recent valuation was no longer valid, including as a result of changes in the stage of development efforts, various exit strategies and their timing, and other scientific developments that could be related to the Company’s valuation, or, at a minimum, annually. Third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Income Taxes Deferred income tax assets and liabilities arise from temporary differences associated with differences between the financial statements and tax basis of assets and liabilities, as measured by the enacted tax rates, which are expected to be in effect when these differences reverse. Deferred tax assets and liabilities are classified as current or non-current, depending upon the classification of the asset or liabilities to which they relate. Deferred tax assets and liabilities not related to an asset or liability are classified as current or non-current depending on the periods in which the temporary differences are expected to reverse. Valuation allowances are established when necessary, to reduce deferred tax assets to the amount expected to be realized. We follow the provisions of ASC 740-10, Uncertainty in Income Taxes. We have not recognized a liability as a result of ASC 740-10. A reconciliation of the beginning and ending amount of unrecognized tax benefits has not been provided since there is no unrecognized benefit since the date of adoption and we have not recognized interest expense or penalties as a result of ASC 740-10. If there were an unrecognized tax benefit, we would recognize interest accrued related to unrecognized tax benefits in interest expense and penalties in operating expenses. We have identified Denmark and the U.S. as our major tax jurisdictions. Net Loss Per Share We calculate basic and diluted net loss per share attributable to ordinary shareholders in conformity with the two-class method required for participating securities. Our convertible preference shares were participating securities in Company distributions. The net loss attributable to ordinary shareholders is not allocated to the convertible preference shares as the holders of convertible preference shares do not have a contractual obligation to share in losses. Cumulative dividends on preference shares are added to net loss to arrive at net loss available to ordinary shareholders. Under the two-class method, basic net loss per share attributable to ordinary shareholders is computed by dividing the net loss attributable to ordinary shareholders by the weighted average number of ordinary shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is calculated by dividing net loss by the weighted average number of shares of ordinary shares and potential dilutive common share equivalents outstanding during the period if the effect is dilutive. Potentially dilutive securities include stock options to purchase common stock of the Company. In all periods presented, the Company’s outstanding stock options were excluded from the calculation of diluted net loss per share because their effects were anti-dilutive. Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker (CODM), in deciding how to allocate resources to an individual segment and in assessing performance. Our CODM is our chief executive officer. We have determined we operate in a single segment. Other Comprehensive Income (Loss) OCI is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Our OCI includes currency translation from the Euro, the functional currency of IO Biotech ApS and IO Biotech Limited, to the U.S. Dollar, our reporting currency. Emerging Growth Company Status We are an emerging growth company, as defined in the Jumpstart Our Business Startups Act (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. We have 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 we (1) are no longer an emerging growth company or (2) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. Recently Issued Accounting Standards In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging , and Topic 825, Financial Instruments . The guidance is effective for fiscal years beginning after December 15, 2022. The Company is assessing the potential impact of adopting ASU 2016-13 on our financial statements and financial statement disclosures and does not currently expect a material impact on our financial statements or financial statement disclosures upon adoption. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes . ASU 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. The Company has adopted the standard effective for fiscal year December 31, 2022. The adoption of the standard has not had a material impact on our financial statements or financial statement disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . ASU 2020-06 will simplify the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock. Limiting the accounting models results in fewer embedded conversion features being separately recognized from the host contract as compared with current GAAP. Convertible instruments that continue to be subject to separation models are (1) those with embedded conversion features that are not clearly and closely related to the host contract, that meet the definition of a derivative, and that do not qualify for a scope exception from derivative accounting and (2) convertible debt instruments issued with substantial premiums for which the premiums are recorded as paid-in capital. ASU 2020-06 also amends the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusions. ASU 2020-06 will be effective for us beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We are currently assessing the impact adoption of ASU 2020-06 will have on our financial statements and disclosures. Other than the items noted above, there have been no new accounting pronouncements not yet effective or adopted in the current year that we believe have a significant impact, or potential significant impact, to our consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements 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 are performed in a manner to maximize the use of observable inputs and minimize the use of unobservable inputs. The Company classified its money market funds within Level 1 as the fair value of the funds are based on their quoted market prices in an active market. The following tables present information about our 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 as of December 31, 2022 and 2021 (in thousands): December 31, 2022 Total Level 1 Level 2 Level 3 Assets Money market funds(1) $ 87,971 $ 87,971 $ — $ — Total assets measured at fair value $ 87,971 $ 87,971 $ — $ — December 31, 2021 Total Level 1 Level 2 Level 3 Assets Money market funds(1) $ 101,561 $ 101,561 $ — $ — Total assets measured at fair value $ 101,561 $ 101,561 $ — $ — (1) Money market funds with maturities of 90 days or less at the date of purchase are included within cash and cash equivalents in the accompanying consolidated balance sheets and are recognized at fair value. The following table presents a roll-forward of the fair value of the convertible note and preference shares tranche obligations for which fair value is determined by Level 3 inputs (in thousands): Preference Shares Tranche Obligations Balance, December 31, 2020 — Addition on issuance of Class C preference shares 2,425 Fair value adjustments 26,830 Currency exchange ( 979 ) Settlement of preference shares tranche obligation through issuance of preference shares ( 28,276 ) Balance, December 31, 2021 $ — Valuation techniques used to measure fair value maximize the use of relevant observable inputs and minimize the use of unobservable inputs. Our convertible notes and preference shares tranche obligations, which were issued and settled during the year ended December 31, 2021, were classified within Level 3 of the fair value hierarchy because the fair value measurement was based, in part, on significant inputs not observed in the market. As of December 31, 2022 and 2021, the Company only held Level 1 financial instruments, respectively. Our Class C Preference Shares Tranche Obligation was measured at fair value using a Black-Scholes option pricing valuation methodology. The fair value of Class C Preference Shares Tranche Obligation included inputs not observable in the market and thus represents a Level 3 measurement. The option pricing valuation methodology utilized required inputs based on certain subjective assumptions, including (1) expected stock price volatility; (2) calculation of an expected term; (3) a risk-free interest rate; and (4) expected dividends. The assumptions utilized to value the class C Preference Shares Tranche Obligation during 2021 were (1) expected stock price volatility of 73.7 %; (2) remaining term of 0.3 years; (3) a risk-free interest rate of 0.05 %; and (4) an expectation of no dividends. There were no transfers among Level 1, Level 2 or Level 3 categories in the years ended December 31, 2 0 22 and 2 0 21 .

License and Collaboration Agree

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License and Collaboration Agreements	4. License and Collaboration Agreements Clinical Trial Collaboration and Supply Agreements with MSD International GmbH In February 2018, we entered into a clinical collaboration with MSD International GmbH (MSDIG), to evaluate IO102 in combination with KEYTRUDA ® (pembrolizumab) in first-line treatment of patients with metastatic non-small cell lung cancer. Under the terms of the collaboration with MSDIG, we will conduct an international Phase 1/2 study to evaluate a combination therapy of IO102 and KEYTRUDA ® . We will sponsor the clinical trials and MSDIG will provide KEYTRUDA ® to be used in the clinical trials free of charge. We and MSDIG will be responsible for our own internal costs and expenses to support the study and we shall bear all other costs associated with conducting the study, including costs of providing IO102 for use in the study. The rights to the data from the clinical trials will be shared by us and MSDIG and we will maintain global commercial rights to IO102. In September 2021, we entered into a clinical collaboration with MSD to evaluate IO102-IO103 in combination with KEYTRUDA ® versus KEYTRUDA ® alone in treatment of patients with metastatic (advanced) melanoma. Under the terms of the collaboration with MSD, we will conduct an international Phase 3 study to evaluate a combination therapy of IO102-IO103 and KEYTRUDA ® . We will sponsor the clinical trials and MSD will provide KEYTRUDA ® to be used in the clinical trials free of charge. We and MSD will be responsible for our own internal costs and expenses to support the study and we shall bear all other costs associated with conducting the study, including costs of providing IO102-IO103 for use in the study. The rights to the data from the clinical trials will be shared by us and MSD and we will maintain global commercial rights to IO102-IO103. In December 2021, we entered into a clinical collaboration with MSD to evaluate IO102-IO103 in combination with KEYTRUDA ® in previously untreated patients with three different tumor types— metastatic NSCLC, SCCHN, and UBC. Under the terms of the collaboration with MSD, we will conduct an international Phase 2 study to evaluate a combination therapy of IO102-IO103 and KEYTRUDA ® . We will sponsor the clinical trials and MSD will provide KEYTRUDA ® to be used in the clinical trials free of charge. We and MSD will be responsible for our own internal costs and expenses to support the study and we shall bear all other costs associated with conducting the study, including costs of providing IO102-IO103 for use in the study. The rights to the data from the clinical trials will be shared by us and MSD and we will maintain global commercial rights to IO102-IO103. In November 2022, we entered into a clinical collaboration with MSD to evaluate IO102-IO103 in combination with KEYTRUDA ® as a neo-adjuvant/adjuvant therapy for patients with metastatic melanoma and SSCHN. Under the terms of the collaboration with MSD, we will conduct an international Phase 2 study to evaluate a combination therapy of IO102-IO103 and KEYTRUDA ® . We will sponsor the clinical trials and MSD will provide KEYTRUDA ® to be used in the clinical trials free of charge. We and MSD will be responsible for our own internal costs and expenses to support the study and we shall bear all other costs associated with conducting the study, including costs of providing IO102-IO103 for use in the study. The rights to the data from the clinical trials will be shared by us and MSD and we will maintain global commercial rights to IO102-IO103. Agreements with Herlev Hospital The Company has a number of existing agreements with the Herlev University Hospital in Denmark (Herlev) for scientific and other support of our ongoing development activities. In January 2021, the Company entered into an additional agreement with Herlev regarding the payment of specific services whereupon in addition to any consideration payable by the Company to Herlev pursuant to the existing agreements we were required to pay a fee to Herlev of DKK 5.0 million (approximately $ 0.8 million) in the event of an initial public offering or other liquidity event whereby all or substantially all of the value of the Company is realized in consideration for cash. The Company consummated its IPO in November 2021, resulting in this payment to Herlev becoming payable. Additionally, upon the completion of the IPO, the Company was obligated to make payments to Herlev in the aggregate amount of DKK 13.2 million, (which is approximately $ 2.1 million based on the exchange rate of DKK 6.54 to one U.S. Dollar on December 31, 2021). In total, the Company accrued for and expensed $ 2.9 million in consideration payable to Herlev Hospital in accordance with existing agreements. The $ 2.9 million was expensed to research and development expense for the year ended December 31, 2021 and was subsequently paid in February 2022.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Current Assets	5. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Prepaid contract research and development costs $ 1,695 $ 4,770 Insurance 1,716 3,197 Research and development tax credit receivable 792 841 Value-added tax refund receivable 741 1,250 Other 685 149 Total prepaid expenses and other current assets $ 5,629 $ 10,207

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, Net Property and equipment, net consist of the following (in thousands): December 31, 2022 2021 Laboratory equipment $ 544 $ 68 Computer hardware 79 35 Office furniture 233 64 Less: accumulated depreciation ( 115 ) ( 12 ) Total Property and Equipment, net $ 741 $ 155 For the years ended December 31, 2022 and 2021, the Company recognized $ 0.1 million and $ 0.0 million , respectively, of depreciation expense in the statements of operations.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	7. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2022 2021 Accrued contract research and development costs $ 1,936 $ 3,861 Professional fees 407 1,028 Employee compensation costs 1,863 1,027 Other liabilities 1,951 461 Total accrued expenses and other current liabilities $ 6,157 $ 6,377

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Leases	8. Leases On January 1, 2022, the Company adopted ASC 842 using the modified retrospective transition approach allowed under ASU 2018-11 which releases companies from presenting comparative periods and related disclosures under ASC 842 and requires a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption (Note 2). The Company had an immaterial cumulative-effect adjustment to the opening balance of accumulated deficit as of January 1, 2022. The Company is party to three operating leases for laboratory and office space. The Company’s finance leases are immaterial both individually and in the aggregate. The Company has elected to apply the short-term lease exception to all leases of one year or less. As of December 31, 2022 , this exception applied to one operating lease for office and laboratory space in Denmark that expired on December 31, 2022 and another operating lease for office space in the UK that is payable month to month. Further, the Company has applied the guidance in ASC 842 to our corporate office and laboratory leases and has determined that these should be classified as operating leases. Consequently, as a result of the adoption of ASC 842 on January 1, 2022, we recognized an ROU lease asset of approximately $ 2.3 million with a corresponding lease liability of approximately $ 2.4 million based on the present value of the minimum rental payments of such leases. In accordance with ASC 842, the beginning balance of the ROU lease asset was reduced by the existing deferred rent liability at inception of approximately $ 0.1 million. In the consolidated balance sheet as of December 31, 2022 , the Company has an ROU asset balance of $ 2.5 million and a current and non-current lease liability of $ 0.5 million and $ 2.3 million, respectively, relating to the ROU lease asset. The balance of both the ROU lease asset and the lease liabilities primarily consists of future payments under the Company’s office leased in New York, New York, Rockville, Maryland and Copenhagen, Denmark. The Company is party to an operating lease in Copenhagen, Denmark for office and laboratory space that commenced in March 2021 with the initial term set to expire in January 2025. Base rent for this initial lease was approximately $ 0.1 million annually. The Company amended its operating lease in Copenhagen, Denmark on September 1, 2022 with a new term set to expire in December 2027. The base rent for the amended lease is approximately $ 0.2 million annually. The Company is party to an operating lease in New York, New York for office and laboratory space that commenced in October 2021 with the initial term set to expire in January 2027. Base rent for this lease is approximately $ 0.2 million annually. The Company is party to an operating lease in Rockville, Maryland for office and laboratory space that commenced in December 2021 with the initial term set to expire in May 2027. Base rent for this lease is approximately $ 0.3 million annually. Rent expense for the years ended December 31, 2022 and 2021 was $ 0.8 million and $ 0.3 million, respectively. Quantitative information regarding the Company’s leases for the year ended December 31, 2022 is as follows (in thousands): Year ended Lease Cost December 31, 2022 Operating lease cost $ 755 Operating cash flows paid for amounts included in the measurement of lease liabilities $ 419 Operating lease liabilities arising from obtaining right‑of‑use assets $ 2,600 Remaining lease term (years) 4.47 Weighted average discount rate 6.5 % Future lease payments (undiscounted) under noncancelable leases are as follows as of December 31, 2022 (in thousands): Future Lease Payments Amount 2023 $ 678 2024 711 2025 731 2026 751 2027 354 Thereafter — Total $ 3,225 The Company’s leases do not provide an implicit rate, therefore the Company used its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company used the incremental borrowing rate on January 1, 2022 for operating leases that commenced prior to that date, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies From time to time, we may be party to litigation arising in the ordinary course of its business. We were not subject to any material legal proceedings during the years ended December 31, 2022 and 2021, and, to our knowledge, no material legal proceedings are currently pending or threatened. Contractual Obligations and Commitments We enter into contracts in the ordinary course of business with third-party service providers for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts generally provide for termination upon notice of 30 to 90 days , and therefore, we believe that our non-cancelable obligations under these agreements are not material and we cannot reasonably estimate whether they will occur. However, in the event of a termination of any contracts with CROs or other institutions and with respect to active patients enrolled in our clinical trials, we may be financially obligated for a period beyond the contractual termination notice periods. We may also enter into additional research, manufacturing, supplier, lease and other agreements in the future, which may require up-front payments and even long-term commitments of cash.. Indemnification Agreements We enter into certain types of contracts that contingently requires us to indemnify various parties against claims from third parties. These contracts primarily relate to procurement, service, consultancy or license agreements under which we may be required to indemnify vendors, service providers or licensees for certain claims, including claims that may be brought against them arising from our acts or omissions with respect to our products, technology, intellectual property or services. The Company, as permitted under Delaware law and in accordance with its amended and restated certification of incorporation and amended and restated bylaws and pursuant to indemnification agreements with certain of its officers and directors, indemnifies its officers and directors for certain events or occurrences, subject to certain limits, which the officer or director is or was serving at the Company’s request in such capacity. From time to time, we may receive indemnification claims under these contracts in the normal course of business. In the event that one or more of these matters were to result in a claim against us, an adverse outcome, including a judgment or settlement, may cause a material adverse effect on our future business, operating results or financial condition. It is not possible to estimate the maximum amount potentially payable under these contracts since we have no history of prior indemnification claims and the unique facts and circumstances involved in each particular claim will be determinative.

Convertible Preference Shares

Convertible Preference Shares	12 Months Ended
	Dec. 31, 2022
Temporary Equity Disclosure [Abstract]
Convertible Preference Shares	10. Convertible Preference Shares As of December 31, 2022 and 2 0 21 , we had no preference shares authorized, issued and outstanding. Sales and Issuances of Preference Shares During the Years Ended December 31, 2022 and 2021 In January 2021, we completed an investment agreement, Class C Investment Agreement, for the sale and issuance of up to 1,263,804 Class C preference shares to new investors and existing related-party investors at a subscription price of $ 121.55 per share. Then, pursuant to the Class C Investment Agreement, we issued 505,520 Class C preference shares for gross cash proceeds of $ 61.5 million. The Class C Investment Agreement further provided for a milestone closing in the event of certain development milestones before April 2022, whereby purchasers of Class C preference shares are obligated to a further subscription amount of $ 88.4 million, or the Preference Shares Tranche Obligation, which resulted in a further issuance of 689,344 Class C preference shares at a subscription price of $ 128.19 per share. We incurred issuance costs of $ 0.3 million in connection with the issuances of the Class C preference shares. We concluded that the Preference Shares Tranche Obligation met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the class C preference shares. Therefore, we allocated the proceeds received from the issuance of shares under the Class C Investment Agreement between the Preference Shares Tranche Obligation and the Class C preference shares. The fair value of the Preference Shares Tranche Obligation of $ 2.4 million on issuance was allocated from the $ 61.5 million proceeds of the Class C preference shares financing and was classified as a current liability on the balance sheet as the Class C preference shares would become redeemable upon a Deemed Liquidation Event, the occurrence of which is not within our control. In March 2021, prior to a milestone closing, an investor elected to purchase and we issued 35,825 Class C preference shares for gross cash proceeds of $ 4.2 million pursuant to the Class C Investment Agreement. As a result of entering into a collaboration agreement with Merck in September 2021, the number of Class C preference shares issued in March 2021 was adjusted downward to 32,568 Class C preference shares. In October 2021, investors purchased and we issued 656,776 Class C preference shares for gross cash proceeds of $ 84.1 million pursuant to the Class C Investment Agreement, resulting in the settlement of the preference shares tranche obligations. Immediately prior to consummation of our IPO, all outstanding Class B and Class C preference shares were converted into 20,415,213 shares of common stock.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Class of Stock Disclosures [Abstract]
Stockholders' Equity	11. Stockholders' Equity Common and Preferred Stock In November 2021, we completed our IPO selling an aggregate of 8,222,500 shares of common stock at $ 14.00 per share, which included 1,072,500 shares that represented the full exercise of an option to purchase additional shares granted to the underwriters in connection with the IPO. The offering resulted in $ 103.3 million of net proceeds to us, after deducting underwriting discounts and commissions and other offering expenses. Upon the closing of our IPO, we filed an amended and restated certificate of incorporation, which authorized us to issue 300,000,000 shares of common stock and 5,000,000 shares of preferred stock. The shares of preferred stock are currently undesignated. Common stockholders are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. Common stockholders are entitled to receive dividends, if and when declared by the Company's board of directors (Board). No dividends have been declared or paid by us through December 31, 2022. As of December 31, 2022 and 2021 , the Company had 28,815,267 common shares outstanding, respectively.

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Equity-Based Compensation	12. Equity-Based Compensation Employee Equity Plan Prior to our IPO, we issued warrants to certain employees, board members and advisors (Pre-IPO Plan). Each vested warrant entitled the warrant holder to a single class A ordinary share. Holders of stock warrants were entitled to exercise the vested portion of the stock warrant. Stock warrants generally vest over a three-year period and expire five years from the vest date. In November 2021, our Board adopted, and our stockholders approved, the 2021 Equity Incentive Plan (2021 Equity Plan), which became effective on November 4, 2021. The 2021 Equity Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, awards of restricted stock, restricted stock units and other stock-based awards. The number of shares of our common stock reserved for issuance under the 2021 Equity Plan is equal to 2,465,150 , subject to an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2022 and continuing until, and including, the fiscal year ending December 31, 2031, equal to the lesser of (1) 4 % of the number of shares of common stock outstanding on the first day of such fiscal year or (2) such other amount determined by our Board . The 2,396,413 outstanding warrants granted under the Pre-IPO Plan were transferred to the 2021 Equity Plan and no further warrants were available to be issued under the Pre-IPO Plan. As of December 31, 2022, we had 1,389,248 options available for future grant under the 2021 Equity Plan. The following table summarizes our stock options activity for the years ended December 31, 2022 and 2021: Number of Weighted- Weighted- Aggregate Outstanding December 31, 2020 89,935 $ 15.00 4.6 $ — Granted 2,981,678 $ 14.58 — $ — Outstanding December 31, 2021 3,071,613 $ 13.12 8.5 $ — Granted 1,211,155 $ 5.34 — $ — Cancelled or forfeited ( 362,596 ) $ 12.51 — $ — Outstanding, December 31, 2022 3,920,172 $ 10.77 8.1 $ — Exercisable at December 31, 2022 993,841 $ 13.04 7.3 $ — 2021 Employee Stock Purchase Plan In November 2021, our board of directors adopted and our stockholders approved the 2021 Employee Stock Purchase Plan (2021 ESPP), which became effective on November 4, 2021. The number of shares of our common stock reserved for issuance under the 2021 ESPP is equal to 257,272 , subject to an annual increase, to be added on the first day of each fiscal year, beginning January 1, 2023, equal to the lesser of (1) 1 % of the number of shares of common stock outstanding on the first day of such fiscal year; (2) 257,272 shares of our common stock; or (3) such other amount determined by our board of directors. As of December 31, 2022, the Board had not yet approved any offering under the 2021 ESPP. Equity-Based Compensation In October 2021, our Board approved the amendment of all nonvested warrant awards issued in July and August 2021 with an exercise price of $ 19.62 per share to reduce the exercise price of such warrants to $ 12.64 per share. Warrants to purchase an aggregate of 670,849 shares of our Class A ordinary shares were modified. The vesting schedule of such awards was not modified. The modification resulted in a $ 0.6 million charge which will be recognized over the remaining vesting periods of each award averaging 3.75 years. All share-based awards granted are measured based on the fair value on the date of the grant and compensation expense is recognized with respect to those awards over the requisite service period, which is generally the vesting period of the respective award. Forfeitures related to equity-based compensation awards are recognized as they occur, and we reverse any previously recognized compensation cost associated with forfeited awards in the period the forfeiture occurs. For the years ended December 31, 2022 and 2021, we recorded equity-based compensation expense of $ 7.0 million and $ 1.8 million , respectively, related to the issuance of stock options and warrants. As of December 31, 2022, there was $ 17.5 million of unrecognized compensation cost related to unvested stock-based compensation arrangements that is expected to be recognized over a weighted average period of 2.8 years. The fair values of the options granted were estimated based on the Black-Scholes model, using the following assumptions: Year Ended December 31, 2022 2021 Expected volatility 74.0 % - 77.3 % 72.9 % - 82.6 % Risk-free interest rate 1.62 % - 4.2 % 0.79 % - 1.45 % Expected term (in years) 5.5 - 6.0 5.5 - 9.0 Expected dividend yield 0 % 0 % Equity-based compensation expense recorded as research and development and general and administrative expenses is as follows (in thousands): December 31, 2022 2021 Research and development $ 2,859 $ 600 General and administrative 4,181 1,191 Total equity-based compensation $ 7,040 $ 1,791

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes We are subject to U.S. federal, state and foreign corporate income taxes. Our loss before provision (benefit) for income taxes for the years ended December 31, 2022 and 2021 consisted of the following (in thousands): Year Ended December 31, 2022 2021 Domestic $ ( 1,885 ) $ 206 Foreign ( 68,300 ) ( 68,017 ) Total $ ( 70,185 ) $ ( 67,811 ) Our provision for income taxes consists of the following (in thousands): Year Ended December 31, 2022 2021 Current: Federal $ 1,059 $ 114 State 86 23 Foreign 52 18 1,197 155 Deferred: Federal 76 ( 72 ) State — ( 15 ) Foreign — — 76 ( 87 ) Total provision for income taxes $ 1,273 $ 68 Reconciliation of Effective Tax Rate Our effective tax rate for the years ended December 31, 2022 and 2021 is different from the statutory rate in the U.S. primarily due to the valuation allowance against deferred tax assets as a result of insufficient sources of income. The reconciliation of the statutory income tax rate to our effective income tax rate is as follows: Year Ended December 31, 2022 2021 Income tax benefit at the statutory rate 21.0 % 21.0 % Permanent differences 0.7 ( 6.5 ) Difference in tax rate 1.0 1.0 R&D Deduction 4.0 — Change in valuation allowance ( 27.4 ) ( 15.6 ) Other ( 1.1 ) — Total ( 1.8 )% ( 0.1 )% Deferred Taxes Deferred tax assets and liabilities represent future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities and for loss carryforwards using enacted tax rates expected to be in effect in the years in which the differences reverse. A valuation allowance is recorded when it is more likely than not that some or all of the deferred tax assets will not be realized. The principal components of the Company’s deferred tax assets consisted of the following (in thousands): December 31, 2022 2021 Deferred tax assets: Net operating loss carryforwards $ 31,338 $ 14,693 Equity-based compensation expense 1,828 345 Accrued compensation 21 88 ROU Lease Liability 618 — Capitalized R&D 1,231 — Other 529 73 Total deferred tax assets $ 35,565 $ 15,199 Valuation allowance ( 34,984 ) ( 15,112 ) Net deferred tax assets $ 581 $ 87 ROU Lease Asset 567 — Other Liabilities 14 — Total deferred tax liabilities 581 — Net deferred tax asset (liability) $ — $ 87 In 2017, the U.S. enacted the Tax Cuts and Jobs Act (the 2017 Tax Act), which contained a provision that requires capitalization and amortization of research and development expenses for tax purposes starting in 2022. Previously, these expenses could be deducted in the year incurred. The implementation of this provision increased our deferred tax asset and valuation allowance by approximately $ 1.2 million in 2022. We determine whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50%. When realization of a deferred tax asset is more likely than not to occur, the benefit related to the deductible temporary differences attributable to operations is recognized as a reduction of income tax expense. Valuation allowances are provided against deferred tax assets when, based on all available evidence, it is considered more likely than not that some portion or all of the recorded deferred tax assets will not be realized in future periods. We cannot be certain that future income in Denmark will be sufficient to realize the Company’s deferred tax assets. Accordingly, a full valuation allowance has been provided against our net deferred tax assets in Denmark. We have also provided a full valuation allowance against our net deferred tax assets in the U.S. for IO Bio US, Inc. The Company's valuation allowance increased by $ 19.9 million in 2022. The increase in 2022 is primarily the result of an increase in net operating loss carryforwards (NOL carryforwards) in Denmark. Available Carryforward Tax Losses As of December 31, 2022 , we had NOL carryforwards of approximately $ 140.5 million that can be carried forward indefinitely according to Danish Tax Authority regulations. Uncertain Tax Positions We determine our uncertain tax positions based on whether and how much of a tax benefit taken by us in our tax filings is more likely than not to be sustained upon examination by the relevant income tax authorities. We have reviewed the tax positions taken, or to be taken, in our tax returns for all tax years currently open to examination by the Danish Tax Authority. As of December 31, 2022 and 2021 , we have no t recorded an uncertain tax position liability. Tax filings in Denmark remain subject to examination by the Danish Tax Authority. As of December 31, 2022, tax y ears 2019 and forward were generally open to examination by the Danish Tax Authority . Other Tax Matters The Company recognizes accrued interest related to unrecognized tax benefits and penalties as income tax expense. The Company does not have any material unrecognized tax benefits which would affect the effective tax rate, if recognized. The Company does not have any unrecognized tax benefits which would reverse within the next twelve months. The Company is eligible for the Danish enhanced research and development tax allowance, providing for an increase in the deductible value of the amount of certain R&D expenditures. For 2019, the deduction is set at 101.5 %. Furthermore, the deduction for R&D expenditures is set at 130 % for 2020 through 2022, 108 % for 2023 through 2025, and 110 % for 2026. The tax allowance is reported as a reduction to research and development expense in the statements of operations. For the years ended December 31, 2022 and 2021, we applied for refundable tax credit of 25 million DKK for each year and a receivable was recorded for $ 0.8 million, respectively.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	14. Net Loss Per Share Basic and diluted net loss per ordinary share is calculated as follows (in thousands except share and per share amounts): Year Ended December 31, 2022 2021 Net loss $ ( 71,458 ) $ ( 67,879 ) Cumulative dividends on Class B and C preference shares — ( 7,108 ) Net loss attributable to common shareholders $ ( 71,458 ) $ ( 74,987 ) Net loss per common share, basic and diluted $ ( 2.48 ) $ ( 17.30 ) Weighted-average number of shares used in computing net loss per common share, basic and diluted 28,815,267 4,335,629 The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per Class A ordinary share, as their effect is anti-dilutive: December 31, 2022 2021 Convertible preference shares — — Stock options to purchase common stock 3,920,172 3,071,613 Stock warrants to purchase Class A ordinary shares — —

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events We have evaluated subsequent events through the date on which the consolidated financial statements were issued. The Company has concluded that no subsequent events have occurred that require disclosure to the consolidated financial statements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States (U.S. GAAP). Any reference in these notes to applicable guidance is meant to refer to U.S. GAAP, as found in the Accounting Standards Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). Prior to the completion of our IPO, we approved a 3.544 -for-1 stock split of our common stock. All share and per share amounts in the balance sheet and notes thereto have been retroactively adjusted for all periods presented to give effect to this split.
Principles of Consolidation	Principles of Consolidation The Company’s consolidated financial statements include the accounts of its subsidiaries IO Biotech ApS, IO Bio US, Inc. and IO Biotech Limited. IO Bio US, Inc., a wholly owned subsidiary of IO Biotech ApS, was incorporated in Delaware in May 2021. IO Biotech Limited, a wholly owned subsidiary of IO Biotech ApS, was incorporated in the UK in August 2021. In November 2021, the Company engaged in a series of transactions, referred to collectively as the Corporate Reorganization. As a result of the Corporate Reorganization, IO Biotech ApS became a wholly-owned subsidiary of IO Biotech, Inc. and accordingly, our consolidated financial statements are those of IO Biotech, Inc. for the periods after the date of the Corporate Reorganization. IO Biotech, Inc. is a holding company formed in October 2021, which, prior to our IPO, had nominal assets and no liabilities, contingencies, or commitments, and which has not conducted any operations prior to our IPO other than acquiring the entire issued and outstanding stock of IO Biotech ApS. The Company, IO Biotech ApS, and the holders of all of the issued and outstanding equity interests of IO Biotech ApS have entered into a Share Contribution and Exchange Agreement, dated as of October 29, 2021, pursuant to which the Corporate Reorganization was effected. Management has concluded it has a single reporting segment for purposes of reporting financial condition and results of operations. All intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect certain reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting periods. Significant items subject to such estimates and assumptions include contract research organization accruals, the fair value of stock-based compensation awards, and valuation of the Company’s deferred tax assets. We base our estimates on historical experience and various other assumptions that we believe to be reasonable under the circumstances. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.
Currency and Currency Translation	Currency and Currency Translation The financial statements are presented in U.S. dollars, our reporting currency. The functional currency of IO Biotech ApS and IO Biotech Limited is the Euro. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the functional currency are included in other income and expense in the statements of operations. Assets and liabilities recorded in our Euro functional currency are translated into the U.S. dollar reporting currency at the exchange rate on the balance sheet date. Our expenses in the Euro functional currency are translated into the U.S. dollar reporting currency at the average exchange rate prevailing during the year. Resulting translation adjustments are recorded to other comprehensive income (loss) (OCI).
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value. As of December 31, 2022 and 2021 we had money market funds of $ 88.0 million and $ 101.6 million , respectively, which are included in cash and cash equivalents and reported at fair value (Note 3).
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk We maintain our cash in bank deposit and checking accounts that at times exceed insured limits. We have not experienced any losses in such accounts and believe we are not exposed to any significant credit risk, however, we are exposed to the potential loss of uninsured deposits should a financial institution we maintain our cash deposits with fail.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price we would receive to sell an investment in a timely transaction or pay to transfer a liability in a timely transaction with an independent buyer in the principal market, or in the absence of a principal market, the most advantageous market for the investment or liability. A framework is used for measuring fair value utilizing a three-tier hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are as follows: Level 1 —Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 —Quoted prices in markets that are not considered to be active or financial instrument valuations for which all significant inputs are observable, either directly or indirectly; and Level 3 —Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. Financial instruments are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the investment. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by us in determining fair value is greatest for instruments categorized in Level 3. We monitor the availability of inputs that are significant to the measurement of fair value to assess the appropriate categorization of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances, our policy is to recognize significant transfers between levels at the end of the reporting period. The significance of transfers between levels is evaluated based upon the nature of the financial instrument and size of the transfer relative to total net assets.
Property and Equipment, net	Property and Equipment, net Property and equipment consists of laboratory equipment, computer hardware and office furniture and are recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. The Company estimates useful life on an asset by asset basis, which generally consists of three years for computer hardware, five years for office furniture and five years for laboratory equipment. The Company reviews long-lived assets, such as property and equipment, for impairment when events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. If circumstances require a long-lived asset to be tested for possible impairment, recoverability is measured by comparison of the carrying amount of the assets to estimated future undiscounted cash flows that the assets are expected to generate. If the carrying amount of an asset exceeds its estimated future cash flows, then impairment expense is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the asset. For the years ended December 31, 2022 and 2021 , no impairment expenses were recognized.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. The Company’s research and development expenses consist primarily of costs incurred for the development of its product candidates and include expenses incurred under agreements with contract manufacturing organizations, or CMOs, contract research organizations, or CROs, investigative sites and consultants to conduct clinical trials and preclinical and non-clinical studies, costs to acquire, develop and manufacture supplies for clinical trials and other studies, salaries and related costs, including equity-based compensation, depreciation and other allocated facility-related and overhead expenses and licensing fees and milestone payments incurred under product license agreements where no alternative future use exists. We may obtain grants from public and private funds for our research and development projects. The grant income for a given period is recognized as a cost reimbursement and is typically based on the time and the costs that we have spent on the specific project during that period. During the years ended December 31, 2022 and 2021, we had active cost reimbursement grants with Innovation Fund Denmark. The grants provided partial reimbursement of employment-related costs related to two employees pursuant to Business Ph.D. and Business post-doctoral programs. For the years ended December 31, 2022 and 2021, research and development expenses in the statements of operations include $ 0.03 million and $ 0.1 million, respectively, of grant income cost reimbursement. We have historically met the requirements to receive a tax credit in Denmark of up to 5.5 million Danish Kroner per year for losses resulting from research and development costs of up to 25.0 million Danish Kroner per year. The tax credit is reported as a reduction to research and development expense in the statements of operations. For the years ended December 31, 2022 and 2021 , research and development expenses include refundable tax credits of $ 0.8 million, respectively.
Accrued Research and Development Costs	Accrued Research and Development Costs Substantial portions of our pre-clinical and clinical trials are performed by third-party laboratories, medical centers, CMOs, CROs and other vendors. These vendors generally bill monthly for services performed, or bill based upon milestone achievement. For preclinical studies, we accrue expenses based upon estimated percentage of work completed and the contract milestones remaining. For clinical studies, expenses are accrued based upon the number of patients enrolled, the duration of the study and other investigative costs. We monitor patient enrollment, the progress of clinical studies and related activities to the extent possible through internal reviews of data reported to us by the CROs, correspondence with the CROs and clinical site visits. Our estimates depend on the timeliness and accuracy of the data provided by the CROs regarding the status of each program and total program spending. We periodically evaluate the estimates to determine if adjustments are necessary or appropriate based on information we receive.
Leases	Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASC 842”) to enhance the transparency and comparability of financial reporting related to leasing arrangements. Under this new lease standard, most leases are required to be recognized on the balance sheet as right-of-use (ROU) assets and lease liabilities. Disclosure requirements have been enhanced with the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. Prior to January 1, 2019, U.S. GAAP did not require lessees to recognize assets and liabilities related to operating leases on the balance sheet. The new standard establishes a right-of-use model that requires a lessee to recognize a ROU asset and corresponding lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement as well as the reduction of the right of use asset. The Company has adopted the standard effective January 1, 2022 and has chosen to use the effective date as our date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods prior to January 1, 2022. The new standard provides a number of optional practical expedients in transition. The Company has elected to apply the ‘package of practical expedients’ which allow the Company to not reassess (1) whether existing or expired arrangements contain a lease; (2) the lease classification of existing or expired leases; or (3) whether previous initial direct costs would qualify for capitalization under the new lease standard. The Company has also elected to apply (1) the practical expedient which allows us to not separate lease and non-lease components, for new leases entered into after adoption and (2) the short-term lease exemption for all leases with an original term of less than 12 months, for purposes of applying the recognition and measurements requirements in the new standard. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on specific facts and circumstances, the existence of an identified asset(s), if any, and the Company’s control over the use of the identified asset(s), if applicable. Operating lease liabilities and their corresponding ROU assets are recorded based on the present value of future lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company will utilize the incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. As of the ASC 842 effective date, the Company’s incremental borrowing rate was approximately 6.5 % based on the remaining lease term of the applicable leases. The Company has elected to combine lease and non-lease components as a single component. Operating leases are recognized on the balance sheet as ROU lease assets, lease liabilities current and lease liabilities non-current. Fixed rents are included in the calculation of the lease balances while variable costs paid for certain operating and pass-through costs are excluded. Lease expense is recognized over the expected term on a straight-line basis.
Convertible Preference Shares	Convertible Preference Shares We classified convertible preference shares outside of stockholders’ equity on our balance sheet as certain liquidation events are not strictly within our control. We recorded the issuance of convertible preference shares at the issuance price less related issuance costs.
Equity-Based Compensation	Equity-Based Compensation We account for stock options granted in accordance with ASC 718, Compensation-Stock Compensation . In accordance with ASC 718, compensation expense is measured at the estimated fair value of the stock options at grant date and is included as compensation expense over the vesting period during which an employee provides service in exchange for the award. All share-based awards granted are measured based on the fair value on the date of the grant and compensation expense is recognized with respect to those awards over the requisite service period, which is generally the vesting period of the respective award. The Company reverses any previously recognized compensation cost associated with forfeited awards in the period the forfeiture occurs. Equity-based compensation expense is classified in the Company’s consolidated statements of operations and comprehensive loss in the same manner in which the award recipients’ payroll costs are classified or in which the award recipients’ service payments are classified. The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes model. The following summarizes the inputs used: Expected volatility : The Company estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies because we lack company-specific historical and implied volatility information due in part to the limited time in which we have operated as a publicly traded company. We expect to continue to do so until such time as we have adequate historical data regarding the volatility of our traded stock price. Expected term : The expected term of the Company’s stock options has been determined based on the expected time to liquidity. The Company uses the simplified method prescribed by the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term of options granted because we lack company-specific historical and implied expected term information due in part to the limited time in which we have operated as a publicly traded company. Risk-free interest rate : The risk-free interest rate is based on the implied yield on a U.S. Treasury security at a constant maturity with a remaining term equal to the expected term of the option granted. Dividends : Expected dividend yield is zero because the Company does not pay cash dividends on common shares and does not expect to pay any cash dividends in the foreseeable future. Prior to the Company's IPO, valuations were updated when facts and circumstances indicated that the most recent valuation was no longer valid, including as a result of changes in the stage of development efforts, various exit strategies and their timing, and other scientific developments that could be related to the Company’s valuation, or, at a minimum, annually. Third-party valuations were performed in accordance with the guidance outlined in the American Institute of Certified Public Accountants’ Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation.
Income Taxes	Income Taxes Deferred income tax assets and liabilities arise from temporary differences associated with differences between the financial statements and tax basis of assets and liabilities, as measured by the enacted tax rates, which are expected to be in effect when these differences reverse. Deferred tax assets and liabilities are classified as current or non-current, depending upon the classification of the asset or liabilities to which they relate. Deferred tax assets and liabilities not related to an asset or liability are classified as current or non-current depending on the periods in which the temporary differences are expected to reverse. Valuation allowances are established when necessary, to reduce deferred tax assets to the amount expected to be realized. We follow the provisions of ASC 740-10, Uncertainty in Income Taxes. We have not recognized a liability as a result of ASC 740-10. A reconciliation of the beginning and ending amount of unrecognized tax benefits has not been provided since there is no unrecognized benefit since the date of adoption and we have not recognized interest expense or penalties as a result of ASC 740-10. If there were an unrecognized tax benefit, we would recognize interest accrued related to unrecognized tax benefits in interest expense and penalties in operating expenses. We have identified Denmark and the U.S. as our major tax jurisdictions.
Net Loss Per Share	Net Loss Per Share We calculate basic and diluted net loss per share attributable to ordinary shareholders in conformity with the two-class method required for participating securities. Our convertible preference shares were participating securities in Company distributions. The net loss attributable to ordinary shareholders is not allocated to the convertible preference shares as the holders of convertible preference shares do not have a contractual obligation to share in losses. Cumulative dividends on preference shares are added to net loss to arrive at net loss available to ordinary shareholders. Under the two-class method, basic net loss per share attributable to ordinary shareholders is computed by dividing the net loss attributable to ordinary shareholders by the weighted average number of ordinary shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is calculated by dividing net loss by the weighted average number of shares of ordinary shares and potential dilutive common share equivalents outstanding during the period if the effect is dilutive. Potentially dilutive securities include stock options to purchase common stock of the Company. In all periods presented, the Company’s outstanding stock options were excluded from the calculation of diluted net loss per share because their effects were anti-dilutive.
Segments	Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker (CODM), in deciding how to allocate resources to an individual segment and in assessing performance. Our CODM is our chief executive officer. We have determined we operate in a single segment.
Other Comprehensive Income (loss)	Other Comprehensive Income (Loss) OCI is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Our OCI includes currency translation from the Euro, the functional currency of IO Biotech ApS and IO Biotech Limited, to the U.S. Dollar, our reporting currency.
Emerging Growth Company Status	Emerging Growth Company Status We are an emerging growth company, as defined in the Jumpstart Our Business Startups Act (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. We have 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 we (1) are no longer an emerging growth company or (2) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging , and Topic 825, Financial Instruments . The guidance is effective for fiscal years beginning after December 15, 2022. The Company is assessing the potential impact of adopting ASU 2016-13 on our financial statements and financial statement disclosures and does not currently expect a material impact on our financial statements or financial statement disclosures upon adoption. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes . ASU 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. It also clarifies and simplifies other aspects of the accounting for income taxes. The Company has adopted the standard effective for fiscal year December 31, 2022. The adoption of the standard has not had a material impact on our financial statements or financial statement disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . ASU 2020-06 will simplify the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock. Limiting the accounting models results in fewer embedded conversion features being separately recognized from the host contract as compared with current GAAP. Convertible instruments that continue to be subject to separation models are (1) those with embedded conversion features that are not clearly and closely related to the host contract, that meet the definition of a derivative, and that do not qualify for a scope exception from derivative accounting and (2) convertible debt instruments issued with substantial premiums for which the premiums are recorded as paid-in capital. ASU 2020-06 also amends the guidance for the derivatives scope exception for contracts in an entity’s own equity to reduce form-over-substance-based accounting conclusions. ASU 2020-06 will be effective for us beginning after December 15, 2023. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We are currently assessing the impact adoption of ASU 2020-06 will have on our financial statements and disclosures. Other than the items noted above, there have been no new accounting pronouncements not yet effective or adopted in the current year that we believe have a significant impact, or potential significant impact, to our consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Assets Measured at Fair Value	The following tables present information about our 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 as of December 31, 2022 and 2021 (in thousands): December 31, 2022 Total Level 1 Level 2 Level 3 Assets Money market funds(1) $ 87,971 $ 87,971 $ — $ — Total assets measured at fair value $ 87,971 $ 87,971 $ — $ — December 31, 2021 Total Level 1 Level 2 Level 3 Assets Money market funds(1) $ 101,561 $ 101,561 $ — $ — Total assets measured at fair value $ 101,561 $ 101,561 $ — $ — (1) Money market funds with maturities of 90 days or less at the date of purchase are included within cash and cash equivalents in the accompanying consolidated balance sheets and are recognized at fair value.
Roll-forward of Fair Value of Convertible Note and Preference Shares Tranche Obligations for Which Fair Value Determined by Level 3 Inputs	The following table presents a roll-forward of the fair value of the convertible note and preference shares tranche obligations for which fair value is determined by Level 3 inputs (in thousands): Preference Shares Tranche Obligations Balance, December 31, 2020 — Addition on issuance of Class C preference shares 2,425 Fair value adjustments 26,830 Currency exchange ( 979 ) Settlement of preference shares tranche obligation through issuance of preference shares ( 28,276 ) Balance, December 31, 2021 $ —

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): December 31, 2022 2021 Prepaid contract research and development costs $ 1,695 $ 4,770 Insurance 1,716 3,197 Research and development tax credit receivable 792 841 Value-added tax refund receivable 741 1,250 Other 685 149 Total prepaid expenses and other current assets $ 5,629 $ 10,207

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consist of the following (in thousands): December 31, 2022 2021 Laboratory equipment $ 544 $ 68 Computer hardware 79 35 Office furniture 233 64 Less: accumulated depreciation ( 115 ) ( 12 ) Total Property and Equipment, net $ 741 $ 155

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2022
Payables and Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2022 2021 Accrued contract research and development costs $ 1,936 $ 3,861 Professional fees 407 1,028 Employee compensation costs 1,863 1,027 Other liabilities 1,951 461 Total accrued expenses and other current liabilities $ 6,157 $ 6,377

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Schedule of Quantitative Information Regarding Leases	Quantitative information regarding the Company’s leases for the year ended December 31, 2022 is as follows (in thousands): Year ended Lease Cost December 31, 2022 Operating lease cost $ 755 Operating cash flows paid for amounts included in the measurement of lease liabilities $ 419 Operating lease liabilities arising from obtaining right‑of‑use assets $ 2,600 Remaining lease term (years) 4.47 Weighted average discount rate 6.5 %
Schedule of Future Lease Payments (Undiscounted) under Noncancelable Leases	Future lease payments (undiscounted) under noncancelable leases are as follows as of December 31, 2022 (in thousands): Future Lease Payments Amount 2023 $ 678 2024 711 2025 731 2026 751 2027 354 Thereafter — Total $ 3,225

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rental Payments Under Noncancellable Leases	Future lease payments (undiscounted) under noncancelable leases are as follows as of December 31, 2022 (in thousands): Future Lease Payments Amount 2023 $ 678 2024 711 2025 731 2026 751 2027 354 Thereafter — Total $ 3,225

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Stock Options Activity	The following table summarizes our stock options activity for the years ended December 31, 2022 and 2021: Number of Weighted- Weighted- Aggregate Outstanding December 31, 2020 89,935 $ 15.00 4.6 $ — Granted 2,981,678 $ 14.58 — $ — Outstanding December 31, 2021 3,071,613 $ 13.12 8.5 $ — Granted 1,211,155 $ 5.34 — $ — Cancelled or forfeited ( 362,596 ) $ 12.51 — $ — Outstanding, December 31, 2022 3,920,172 $ 10.77 8.1 $ — Exercisable at December 31, 2022 993,841 $ 13.04 7.3 $ —
Summary of Assumptions for Estimated Fair Value of Options	The fair values of the options granted were estimated based on the Black-Scholes model, using the following assumptions: Year Ended December 31, 2022 2021 Expected volatility 74.0 % - 77.3 % 72.9 % - 82.6 % Risk-free interest rate 1.62 % - 4.2 % 0.79 % - 1.45 % Expected term (in years) 5.5 - 6.0 5.5 - 9.0 Expected dividend yield 0 % 0 %
Schedule of Equity-based Compensation Expense	Equity-based compensation expense recorded as research and development and general and administrative expenses is as follows (in thousands): December 31, 2022 2021 Research and development $ 2,859 $ 600 General and administrative 4,181 1,191 Total equity-based compensation $ 7,040 $ 1,791

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Loss Before Provision (Benefit) for Income Taxes	Our loss before provision (benefit) for income taxes for the years ended December 31, 2022 and 2021 consisted of the following (in thousands): Year Ended December 31, 2022 2021 Domestic $ ( 1,885 ) $ 206 Foreign ( 68,300 ) ( 68,017 ) Total $ ( 70,185 ) $ ( 67,811 )
Schedule of Provision for Income Taxes	Our provision for income taxes consists of the following (in thousands): Year Ended December 31, 2022 2021 Current: Federal $ 1,059 $ 114 State 86 23 Foreign 52 18 1,197 155 Deferred: Federal 76 ( 72 ) State — ( 15 ) Foreign — — 76 ( 87 ) Total provision for income taxes $ 1,273 $ 68
Reconciliation of the Statutory Income Tax Rate to our Effective Income Tax Rate	The reconciliation of the statutory income tax rate to our effective income tax rate is as follows: Year Ended December 31, 2022 2021 Income tax benefit at the statutory rate 21.0 % 21.0 % Permanent differences 0.7 ( 6.5 ) Difference in tax rate 1.0 1.0 R&D Deduction 4.0 — Change in valuation allowance ( 27.4 ) ( 15.6 ) Other ( 1.1 ) — Total ( 1.8 )% ( 0.1 )%
Schedule of Principal Components of Deferred Tax Assets	The principal components of the Company’s deferred tax assets consisted of the following (in thousands): December 31, 2022 2021 Deferred tax assets: Net operating loss carryforwards $ 31,338 $ 14,693 Equity-based compensation expense 1,828 345 Accrued compensation 21 88 ROU Lease Liability 618 — Capitalized R&D 1,231 — Other 529 73 Total deferred tax assets $ 35,565 $ 15,199 Valuation allowance ( 34,984 ) ( 15,112 ) Net deferred tax assets $ 581 $ 87 ROU Lease Asset 567 — Other Liabilities 14 — Total deferred tax liabilities 581 — Net deferred tax asset (liability) $ — $ 87 In 2017, the U.S. enacted the Tax Cuts and Jobs Act (the 2017 Tax Act), which contained a provision that requires capitalization and amortization of research and development expenses for tax purposes starting in 2022. Previously, these expenses could be deducted in the year incurred. The implementation of this provision increased our deferred tax asset and valuation allowance by approximately $ 1.2 million in 2022.

Net Loss Per Share (Table)

Net Loss Per Share (Table)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted net loss per ordinary share is calculated as follows (in thousands except share and per share amounts): Year Ended December 31, 2022 2021 Net loss $ ( 71,458 ) $ ( 67,879 ) Cumulative dividends on Class B and C preference shares — ( 7,108 ) Net loss attributable to common shareholders $ ( 71,458 ) $ ( 74,987 ) Net loss per common share, basic and diluted $ ( 2.48 ) $ ( 17.30 ) Weighted-average number of shares used in computing net loss per common share, basic and diluted 28,815,267 4,335,629
Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share	The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per Class A ordinary share, as their effect is anti-dilutive: December 31, 2022 2021 Convertible preference shares — — Stock options to purchase common stock 3,920,172 3,071,613 Stock warrants to purchase Class A ordinary shares — —

Description of Business, Orga_2

Description of Business, Organization and Liquidity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Nov. 09, 2021
Description Of Business Organization And Liquidity [Line Items]
Accumulated deficit		$ (177,739)	$ (106,281)
Net losses		(71,458)	(67,879)
Cash and cash equivalents		$ 142,590	$ 211,531
Common stock, par value		$ 0.001	$ 0.001
Net proceeds from IPO, after deducting underwriting discounts, commissions and offering costs	$ 103,300
Convertible preference share issued upon conversion				20,592,413
Common stock shares outstanding		28,815,267	28,815,267	28,815,267
Common stock shares authorized		300,000,000	300,000,000	300,000,000
Preferred stock shares authorized		5,000,000	5,000,000
Class A Ordinary Shares
Description Of Business Organization And Liquidity [Line Items]
Common stock, par value	$ 0.16
Common stock conversion basis	one for one
Class B Preference Shares
Description Of Business Organization And Liquidity [Line Items]
Common stock, par value	$ 0.001
Common stock conversion basis	one for one
Class C Preference Shares
Description Of Business Organization And Liquidity [Line Items]
Common stock, par value	$ 0.001
Common stock conversion basis	one for one
Undesignated Preferred Stock
Description Of Business Organization And Liquidity [Line Items]
Preferred stock shares authorized		5,000,000		5,000,000
Underwriters
Description Of Business Organization And Liquidity [Line Items]
Shares issued	1,072,500
IPO
Description Of Business Organization And Liquidity [Line Items]
Shares issued	8,222,500
Common stock shares sold, price per share	$ 14

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, kr in Millions		12 Months Ended
	Nov. 01, 2021	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2022 DKK (kr)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 DKK (kr)
Property, Plant and Equipment [Line Items]
Stock split, description	3.544-for-1 stock split
Stock split, conversion ratio	3.544
Money market funds		$ 88,000,000		$ 101,600,000
Impairment expenses		$ 0		$ 0
Operating lease incremental borrowing rate on remaining lease | $ / shares		$ 6.5
Expected dividend yield		0%	0%	0%
Unrecognized tax benefits		$ 0		$ 0
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		3 years	3 years
Office furniture
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years	5 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years	5 years
Research and Development Expense
Property, Plant and Equipment [Line Items]
Grant income cost reimbursement		$ 30,000		100,000
Research and Development Expense | Danish Tax Authority
Property, Plant and Equipment [Line Items]
Refundable tax credit | kr			kr 25
Refundable tax credit receivable		$ 800,000		$ 800,000
Research and Development Expense | Maximum | Danish Tax Authority
Property, Plant and Equipment [Line Items]
Tax credit carryforward | kr					kr 5.5
Refundable tax credit | kr			kr 25

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets Measured at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets
Total assets measured at fair value	$ 87,971	$ 101,561
Money Market Funds [Member]
Assets
Total assets measured at fair value	87,971	101,561
Level 1
Assets
Total assets measured at fair value	87,971	101,561
Level 1 | Money Market Funds [Member]
Assets
Total assets measured at fair value	$ 87,971	$ 101,561

Fair Value Measurements - Roll-

Fair Value Measurements - Roll-forward of Fair Value of Convertible Note and Preference Shares Tranche Obligations for Which Fair Value Determined by Level 3 Inputs (Details) - Level 3 - Preference Shares Tranche Obligations $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Addition in cash on issuance of Class C preference shares	$ 2,425
Fair value adjustments	26,830
Currency exchange	(979)
Settlement of preference shares tranche obligation through issuance of preference shares	$ 28,276

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	$ 0	$ 0
Class C Convertible Preference Stock | Expected Stock Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preference stock measurement input		0.737
Class C Convertible Preference Stock | Remaining Term
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Remaining term		3 months 18 days
Class C Convertible Preference Stock | Risk-Free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preference stock measurement input		0.05
Class C Convertible Preference Stock | Expectation of Dividends
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preference stock measurement input		0

License and Collaboration Agr_2

License and Collaboration Agreements - Additional Information (Details) $ in Thousands, kr in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 DKK (kr)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 DKK (kr)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development expense	$ 46,986		$ 30,152
Herlev
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment fee for specific services	800	kr 5
Consideration payable	$ 2,900
Fee payable for specific services			2,100	kr 13.2
Research and development expense			$ 2,900

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid contract research and development costs	$ 1,695	$ 4,770
Insurance	1,716	3,197
Research and development tax credit receivable	792	841
Value-added tax refund receivable	741	1,250
Other	685	149
Total prepaid expenses and other current assets	$ 5,629	$ 10,207

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 0.1	$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation	$ (115)	$ (12)
Total Property and Equipment, net	741	155
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	544	68
Computer hardware
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	79	35
Office furniture
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 233	$ 64

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued contract research and development costs	$ 1,936	$ 3,861
Professional fees	407	1,028
Employee compensation costs	1,863	1,027
Other liabilities	1,951	461
Total accrued expenses and other current liabilities	$ 6,157	$ 6,377

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) Lease	Dec. 31, 2021 USD ($)	Jan. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Rent expense	$ 800	$ 300
Number of operating leases | Lease	3
Right of use lease asset	$ 2,493		$ 2,300
Lease liability			2,400
Operating lease liability, current	515
Operating lease, liability, non-current	$ 2,275
Deferred rent			$ 100
Office and Laboratory | Denmark
Lessee, Lease, Description [Line Items]
Lease expiration	Dec. 31, 2022
Number of operating leases | Lease	1
Operating lease annual base rent	$ 100
Operating lease amended base rent	200
Office and Laboratory | New York, NY
Lessee, Lease, Description [Line Items]
Operating lease annual base rent	200
Office and Laboratory | Maryland
Lessee, Lease, Description [Line Items]
Operating lease annual base rent	$ 300

Leases - Schedule of Quantitati

Leases - Schedule of Quantitative information Regarding Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 755
Operating cash flows paid for amounts included in the measurement of lease liabilities	419
Operating lease liabilities arising from obtaining right-of-use assets	$ 2,600
Remaining lease term (years)	4 years 5 months 19 days
Weighted average discount rate	6.50%

Leases - Schedule of Future Lea

Leases - Schedule of Future Lease Payments (Undiscounted) under Noncancelable Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2023	$ 678
2024	711
2025	731
2026	751
2027	354
Thereafter	0
Total	$ 3,225

Commitments and Contingencies_2

Commitments and Contingencies (Additional Information) (Details)	12 Months Ended
	Dec. 31, 2022
Minimum
Other Commitments [Line Items]
Contractual obligations termination notice period	30 days
Maximum
Other Commitments [Line Items]
Contractual obligations termination notice period	90 days

Convertible Preference Shares -

Convertible Preference Shares - Additional information (Details) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended
	Oct. 31, 2021 USD ($) shares	Mar. 31, 2021 USD ($) shares	Jan. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) Vote $ / shares shares	Dec. 31, 2021 $ / shares shares	Nov. 09, 2021 shares
Class Of Stock [Line Items]
Preference shares authorized				5,000,000	5,000,000
Preference shares issued				0	0
Preference shares outstanding				0	0
Preference share per share | $ / shares				$ 0.001	$ 0.001
Convertible preference share issued upon conversion						20,592,413
Number of votes per share | Vote				1
Class C Preference Shares
Class Of Stock [Line Items]
Convertible preference shares, shares issued	656,776	35,825	505,520
Temporary equity, subscription price per share | $ / shares			$ 121.55
Proceeds from issuance of preference shares | $	$ 84.1	$ 4.2	$ 61.5
Temporary equity, issuance costs | $			$ 0.3
Convertible preference shares, shares authorized			1,263,804
Number of shares issued for adjusted downward		32,568
Class C Preference Shares | Tranche Obligation
Class Of Stock [Line Items]
Convertible preference shares, shares issued			689,344
Temporary equity, subscription price per share | $ / shares			$ 128.19
Proceeds from issuance of preference shares | $				$ 61.5
Temporary equity, subscription amount | $			$ 88.4
Fair value of preference shares tranche obligation | $				$ 2.4
Class B and Class C Preference Shares
Class Of Stock [Line Items]
Preference shares authorized				0	0
Preference shares issued				0	0
Preference shares outstanding				0	0
Convertible preference share issued upon conversion						20,415,213

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) Vote shares	Dec. 31, 2021 shares	Nov. 09, 2021 shares
Subsidiary, Sale of Stock [Line Items]
Net proceeds from IPO, after deducting underwriting discounts, commissions and offering costs | $	$ 103,300,000
Common stock shares authorized		300,000,000	300,000,000	300,000,000
Preferred stock shares authorized		5,000,000	5,000,000
Number of votes per share | Vote		1
Common stock shares outstanding		28,815,267	28,815,267	28,815,267
IPO
Subsidiary, Sale of Stock [Line Items]
Shares issued	8,222,500
Common stock shares sold, price per share | $ / shares	$ 14
Underwriters
Subsidiary, Sale of Stock [Line Items]
Shares issued	1,072,500
Undesignated Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Preferred stock shares authorized		5,000,000		5,000,000
Dividend Declared
Subsidiary, Sale of Stock [Line Items]
Dividends | $		$ 0
Dividend Paid
Subsidiary, Sale of Stock [Line Items]
Dividends | $		$ 0

Equity-Based Compensation - Add

Equity-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended				12 Months Ended
	Nov. 04, 2021	Nov. 30, 2021	Oct. 31, 2021	Aug. 31, 2021	Jul. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity-based compensation expense						$ 7,040	$ 1,791
Unrecognized compensation cost						$ 17,500
Unrecognized compensation cost, recognition period						2 years 9 months 18 days
Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants granted transferred to plan						1,211,155	2,981,678
Nonvested Warrant Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period						3 years 9 months
Warrants, weighted average exercise price			$ 12.64	$ 19.62	$ 19.62
Modification amount						$ 600
Weighted average period						3 years 9 months
Nonvested Warrant Awards | Class A Ordinary Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants to purchase aggregate shares			670,849
Pre-IPO Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants available for future grant		0
Employee Equity Plan | Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period						3 years
Expiration period from vest date						5 years
Weighted average period						3 years
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	2,465,150
Maximum percentage of shares that may be issued under the plan as a proportion of outstanding capital stock	4%
Number of warrants available for future grant						1,389,248
2021 Equity Incentive Plan | Pre-IPO Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of warrants granted transferred to plan		2,396,413
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance	257,272
2021 Employee Stock Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum percentage of shares that may be issued under the plan as a proportion of outstanding capital stock	1%

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Stock Options Activity (Details) - Warrant - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Warrants, Beginning balance	3,071,613	89,935
Number of Warrants, Granted	1,211,155	2,981,678
Number of Warrants, Cancelled or forfeited	(362,596)
Number of Warrants, Ending balance	3,920,172	3,071,613	89,935
Number of Warrants, Exercisable	993,841
Weighted-average exercise price per share, Beginning balance	$ 13.12	$ 15
Weighted-average exercise price per share, Granted	5.34	14.58
Weighted-average exercise price per share, Cancelled or forfeited	12.51
Weighted-average exercise price per share, Ending balance	10.77	$ 13.12	$ 15
Weighted-average exercise price per share, Exercisable	$ 13.04
Weighted-average remaining contractual term (in years), Outstanding	8 years 1 month 6 days	8 years 6 months	4 years 7 months 6 days
Weighted-average remaining contractual term (in years), Exercisable	7 years 3 months 18 days

Equity-Based Compensation - Sum

Equity-Based Compensation - Summary of Assumptions for Estimated Fair Value of Options (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility minimum	74%	72.90%
Expected volatility maximum	77.30%	82.60%
Risk-free interest rate minimum	1.62%	0.79%
Risk-free interest rate maximum	4.20%	1.45%
Expected dividend yield	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years	9 years

Equity-Based Compensation - S_2

Equity-Based Compensation - Schedule of Equity-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total equity-based compensation	$ 7,040	$ 1,791
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total equity-based compensation	2,859	600
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total equity-based compensation	$ 4,181	$ 1,191

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) kr in Millions	12 Months Ended
	Dec. 31, 2022 DKK (kr)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Provision increase deferred tax assets and valuation allowance		$ 1,200,000
Valuation allowance		19,900,000
Deferred tax assets, credit carryforwards		140,500,000
Unrecognized tax benefits		$ 0	$ 0
Danish Tax Authority
Operating Loss Carryforwards [Line Items]
Open tax year	2019	2019
Danish Tax Authority | Research and Development Expense
Operating Loss Carryforwards [Line Items]
Effective income tax rate				101.50%
Refundable tax credit | kr	kr 25
Refundable tax credit receivable		$ 800,000	$ 800,000
Danish Tax Authority | Research and Development Expense | Maximum
Operating Loss Carryforwards [Line Items]
Refundable tax credit | kr	kr 25
Danish Tax Authority | 2020 through 2022 | Research and Development Expense
Operating Loss Carryforwards [Line Items]
Effective income tax rate	130%	130%
Danish Tax Authority | 2023 through 2025 | Research and Development Expense
Operating Loss Carryforwards [Line Items]
Effective income tax rate	108%	108%
Danish Tax Authority | Period 2026 | Research and Development Expense
Operating Loss Carryforwards [Line Items]
Effective income tax rate	110%	110%

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Domestic	$ (1,885)	$ 206
Foreign	(68,300)	(68,017)
Loss before income tax expense	$ (70,185)	$ (67,811)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 1,059	$ 114
State	86	23
Foreign	52	18
Current	1,197	155
Deferred:
Federal	76	(72)
State		(15)
Deferred	76	(87)
Total provision for income taxes	$ 1,273	$ 68

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Statutory Income Tax Rate to our Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income tax benefit at the statutory rate	21%	21%
Permanent differences	0.70%	(6.50%)
Difference in tax rate	1%	1%
R&D Deduction	4%
Change in valuation allowance	(27.40%)	(15.60%)
Other	(1.10%)
Total	(1.80%)	(0.10%)

Income Taxes - Schedule of Prin

Income Taxes - Schedule of Principal Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 31,338	$ 14,693
Equity-based compensation expense	1,828	345
Accrued compensation	21	88
ROU Lease Liability	618
Capitalized R&D	1,231
Other	529	73
Total deferred tax assets	35,565	15,199
Valuation allowance	(34,984)	(15,112)
Net deferred tax assets	581	87
ROU Lease Asset	567
Other Liabilities	14
Total deferred tax liabilities	$ 581
Net deferred tax asset (liability)		$ 87

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Ordinary Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net loss	$ (71,458)	$ (67,879)
Cumulative dividends on Class B and C preference shares		(7,108)
Net loss attributable to common shareholders	$ (71,458)	$ (74,987)
Net loss per common share, basic	$ (2.48)	$ (17.30)
Net loss per common share, diluted	$ (2.48)	$ (17.30)
Weighted-average number of shares used in computing net loss per common share, basic	28,815,267	4,335,629
Weighted-average number of shares used in computing net loss per common share, diluted	28,815,267	4,335,629

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Stock Options to Purchase Common Stock
Earnings Per Share Basic [Line Items]
Outstanding potentially dilutive securities	3,920,172	3,071,613