Description of Business, Organization and Liquidity	12 Months Ended
Dec. 31, 2024
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 biopharmaceutical company developing novel, immune-modulatory, off-the-shelf therapeutic cancer vaccines based on our T-win® platform. 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. Corporate Reorganization IO Biotech ApS was incorporated in Denmark in December 2014. In November 2021, we completed a corporate reorganization (the “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. 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. IO Biotech, Inc. is a holding company formed in October 2021, which, prior to our initial public offering (“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 entered into a Share Contribution and Exchange Agreement, dated as of October 29, 2021, pursuant to which the Corporate Reorganization was effected. 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 $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 issued and 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 the issuance of 300,000,000 shares of common stock and 5,000,000 shares of preferred stock. The shares of preferred stock are currently undesignated. August 2023 Private Placement On August 9, 2023, the Company completed a private placement transaction (the “Private Placement”), pursuant to which we sold an aggregate of 37,065,647 shares of the Company’s common stock, par value $0.001 per share, and 37,065,647 warrants to purchase up to 37,065,647 shares of common stock (the “Warrants”) to certain institutional investors and existing shareholders (the “Purchasers”). Each Purchaser’s Warrant is exercisable for a number of shares of common stock equal to one hundred percent of the aggregate number of shares of common stock purchased by such Purchaser. The purchase price per share of common stock and Warrant was $2.025 (the “Purchase Price”). The Company received net proceeds from the Private Placement, after deducting $3.2 million in underwriting discounts and commissions and other offering costs, of $71.9 million. Refer to Note 11, "Stockholders' Equity" in in this Annual Report on Form 10-K for additional detail on the Private Placement. At-The-Market Equity Program On February 15, 2023, we filed a new prospectus supplement with the U.S. Securities and Exchange Commission (the “SEC”) with respect to the offer and sale of shares of our Common Stock, with an aggregate offering price of up to $19.5 million, establishing an at-the-market equity program. We also entered into a common stock sales agreement, dated February 15, 2023 (the “Sales Agreement”) by and between the Company and Cowen and Company, LLC for shares with an aggregate offering price of up to $75.0 million, through which we may, from time to time, sell shares through Cowen and Company, LLC, acting as agent and/or principal. Any shares offered and sold through the at-the-market equity program will be issued pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-269569), which was declared effective on February 10, 2023, the prospectus supplement related to the offering that forms a part of the registration statement, and any applicable prospectus supplements that may form a part of the registration statement in the future. The aggregate market value of shares eligible for sale under the prospectus supplement and under the Sales Agreement will be subject to the limitations of General Instruction I.B.6 of Form S-3, to the extent required under such instruction. We have not issued any shares pursuant to our at-the-market equity program as of December 31, 2024. European Investment Bank Term Loan Facility On December 19, 2024, the Company, through its subsidiary, IO Biotech ApS (the “Borrower”) entered into a Finance Contract (the “Finance Contract”) with the European Investment Bank (“EIB”), establishing three tranches of potential financing in an aggregate principal amount of up to €37.5 million, subject to certain conditions precedent (the “EIB Loan Facility”). See Note 8, “Term Loan Facility” in this Annual Report on Form 10-K for additional detail. 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 preclinical 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 preclinical research and clinical development. Our research and development may not 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 of 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, our IPO, the Private Placement and as of December 2024, the EIB Loan Facility. 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 our product development efforts are successful, it is uncertain when, if ever, we will realize significant revenue from product sales. As of December 31, 2024, we had an accumulated deficit of $359.3 million. We have incurred losses and negative cash flows from operations since inception, including net losses of $95.5 million and $86.1 million for the years ended December 31, 2024 and 2023, 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 $60.0 million as of December 31, 2024, along with the first two tranches of the EIB Loan will be sufficient to fund our operating expenses and capital requirements for at least 12 months from the date the financial statements are issued. Further, the Company believes that its operations are scalable and, if there is a need, certain cost reduction measures may be taken to preserve cash. Based on this assessment, management has concluded that there is no substantial doubt about our ability to continue as a going concern for this period, and the financial statements have been prepared on a going concern basis. We have based this evaluation on assumptions that may prove to be wrong, and we could exhaust our capital resources sooner than we expect. Our future capital requirements will depend on many factors, including: • the scope, prioritization and number of our research and development programs; • the scope, progress, results and costs of our clinical trials, including the results of IOB-013, data from which will be available in the third quarter of 2025; • the costs, timing and outcome of regulatory review of our product candidate; • the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims; • the costs to scale up and secure manufacturing arrangements for commercial production of Cylembio® in combination with pembrolizumab as a first-line treatment in advanced melanoma; • the costs of establishing and maintaining sales and marketing capabilities for Cylembio in combination with pembrolizumab as a first-line treatment in advanced melanoma, and any product candidate that obtains regulatory approval; and • the level of sales achieved, and costs related to the commercialization of Cylembio in combination with pembrolizumab as a first-line treatment in advanced melanoma. We will require additional capital to commercialize Cylembio (imsapepimut and etimupepimut, adjuvanted) in combination with pembrolizumab as a first-line treatment in advanced melanoma, and to continue to fund future discovery research, preclinical, clinical activities and commercialization of any of our product candidates. If we receive regulatory approval for Cylembio, we expect to incur significant commercialization expenses related to product manufacturing, sales, marketing and distribution, depending on where we choose to commercialize. Additional funds may not be available on a timely basis, on favorable terms, or at all, and such funds, if raised, may not be sufficient to enable us to continue to implement our long-term business strategy. If we are unable to raise sufficient additional capital, we could be forced to curtail our planned operations and the pursuit of our growth strategy. We will seek additional funding through public financings, debt financings (including EIB which has already been secured), 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 successfully meet scientific data end points from our clinical trials or obtain funding in due time, 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.

Description of Business, Organization and Liquidity

12 Months Ended

Dec. 31, 2024

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 biopharmaceutical company developing novel, immune-modulatory, off-the-shelf therapeutic cancer vaccines based on our T-win® platform. 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.

Corporate Reorganization

IO Biotech ApS was incorporated in Denmark in December 2014. In November 2021, we completed a corporate reorganization (the “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.

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. IO Biotech, Inc. is a holding company formed in October 2021, which, prior to our initial public offering (“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 entered into a Share Contribution and Exchange Agreement, dated as of October 29, 2021, pursuant to which the Corporate Reorganization was effected.

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 $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 issued and 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 the issuance of 300,000,000 shares of common stock and 5,000,000 shares of preferred stock. The shares of preferred stock are currently undesignated.

August 2023 Private Placement

On August 9, 2023, the Company completed a private placement transaction (the “Private Placement”), pursuant to which we sold an aggregate of 37,065,647 shares of the Company’s common stock, par value $0.001 per share, and 37,065,647 warrants to purchase up to 37,065,647 shares of common stock (the “Warrants”) to certain institutional investors and existing shareholders (the “Purchasers”). Each Purchaser’s Warrant is exercisable for a number of shares of common stock equal to one hundred percent of the aggregate number of shares of common stock purchased by such Purchaser. The purchase price per share of common stock and Warrant was $2.025 (the “Purchase Price”). The Company received net proceeds from the Private Placement, after deducting $3.2 million in underwriting discounts and commissions and other offering costs, of $71.9 million. Refer to Note 11, "Stockholders' Equity" in in this Annual Report on Form 10-K for additional detail on the Private Placement.

At-The-Market Equity Program

On February 15, 2023, we filed a new prospectus supplement with the U.S. Securities and Exchange Commission (the “SEC”) with respect to the offer and sale of shares of our Common Stock, with an aggregate offering price of up to $19.5 million, establishing an at-the-market equity program. We also entered into a common stock sales agreement, dated February 15, 2023 (the “Sales Agreement”) by and between the Company and Cowen and Company, LLC for shares with an aggregate offering price of up to $75.0 million, through which we may, from time to time, sell shares through Cowen and Company, LLC, acting as agent and/or principal. Any shares offered and sold through the at-the-market equity program will be issued pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-269569), which was declared effective on February 10, 2023, the prospectus supplement related to the offering that forms a part of the registration statement, and any applicable prospectus supplements that may form a part of the registration statement in the future. The aggregate market value of shares eligible for sale under the prospectus supplement and under the Sales Agreement will be subject to the limitations of General Instruction I.B.6 of Form S-3, to the extent required under such instruction. We have not issued any shares pursuant to our at-the-market equity program as of December 31, 2024.

European Investment Bank Term Loan Facility

On December 19, 2024, the Company, through its subsidiary, IO Biotech ApS (the “Borrower”) entered into a Finance Contract (the “Finance Contract”) with the European Investment Bank (“EIB”), establishing three tranches of potential financing in an aggregate principal amount of up to €37.5 million, subject to certain conditions precedent (the “EIB Loan Facility”). See Note 8, “Term Loan Facility” in this Annual Report on Form 10-K for additional detail.

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 preclinical 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 preclinical research and clinical development. Our research and development may not 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 of 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, our IPO, the Private Placement and as of December 2024, the EIB Loan Facility.

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 our product development efforts are successful, it is uncertain when, if ever, we will realize significant revenue from product sales.

As of December 31, 2024, we had an accumulated deficit of $359.3 million. We have incurred losses and negative cash flows from operations since inception, including net losses of $95.5 million and $86.1 million for the years ended December 31, 2024 and 2023, 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 $60.0 million as of December 31, 2024, along with the first two tranches of the EIB Loan will be sufficient to fund our operating expenses and capital requirements for at least 12 months from the date the financial statements are issued. Further, the Company believes that its operations are scalable and, if there is a need, certain cost reduction measures may be taken to preserve cash. Based on this assessment, management has concluded that there is no substantial doubt about our ability to continue as a going concern for this period, and the financial statements have been prepared on a going concern basis. We have based this evaluation on assumptions that may prove to be wrong, and we could exhaust our capital resources sooner than we expect. Our future capital requirements will depend on many factors, including:

•

the scope, prioritization and number of our research and development programs;

•

the scope, progress, results and costs of our clinical trials, including the results of IOB-013, data from which will be available in the third quarter of 2025;

•

the costs, timing and outcome of regulatory review of our product candidate;

•

the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims;

•

the costs to scale up and secure manufacturing arrangements for commercial production of Cylembio® in combination with pembrolizumab as a first-line treatment in advanced melanoma;

•

the costs of establishing and maintaining sales and marketing capabilities for Cylembio in combination with pembrolizumab as a first-line treatment in advanced melanoma, and any product candidate that obtains regulatory approval; and

•

the level of sales achieved, and costs related to the commercialization of Cylembio in combination with pembrolizumab as a first-line treatment in advanced melanoma.

We will require additional capital to commercialize Cylembio (imsapepimut and etimupepimut, adjuvanted) in combination with pembrolizumab as a first-line treatment in advanced melanoma, and to continue to fund future discovery research, preclinical, clinical activities and commercialization of any of our product candidates. If we receive regulatory approval for Cylembio, we expect to incur significant commercialization expenses related to product manufacturing, sales, marketing and distribution, depending on where we choose to commercialize. Additional funds may not be available on a timely basis, on favorable terms, or at all, and such funds, if raised, may not be sufficient to enable us to continue to implement our long-term business strategy. If we are unable to raise sufficient additional capital, we could be forced to curtail our planned operations and the pursuit of our growth strategy. We will seek additional funding through public financings, debt financings (including EIB which has already been secured), 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 successfully meet scientific data end points from our clinical trials or obtain funding in due time, 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.