UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-41008 IO BIOTECH, INC. (Exact name of Registrant as specified in its Charter) Delaware 87-0909276 (State or other jurisdiction of inc ...

Exhibit 99.1 IO Biotech Announces 2023 Fourth-Quarter and Year-End Results • Completed enrollment of pivotal Phase 3 trial of lead investigational therapeutic cancer vaccine, IO102-IO103, in combination with KEYTRUDA® (pembrolizumab), in patients with advanced melanoma; planned interim analysis for overall response rate (ORR) expected in third quarter of 2024 by independent data monitoring committee • Progressed clinical development of IO102-IO103 with first patient dosed in Phase 2 basket trial of IO102-IO ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________________ to __________________ Commission File Number: 001-41008 IO Biotech, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________________ to __________________ Commission File Number: 001-41008 IO Biotech, Inc. (Exact Name of Registrant as Specified in its Charter) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Delaware 87-09 ...

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) Commission File Number: 001-41008 IO Biotech, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 87-0909276 (State or other jurisdiction of incorporation or organization) Ole Maaløes Vej 3 DK-2200 Copenhagen N Denmark NA (Address of principal executive offices) (Zip ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-41008 IO BIOTECH, INC. (Exact name of Registrant as specified in its Charter) (State or other jurisdiction of incorporation or organi ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________________ to __________________ WASHINGTON, DC 20549 Commission File Number: 001-41008 IO Biotech, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 Delaware 87-0909276 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) Ole Maaløes Vej 3 DK-2200 Copenhagen N Denmark NA (Address of principal executive offices) (Zip Code) Registrant's telephone number, including area code: +45 7070 298 ...

For the transition period from __________________ to __________________ UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number: 001-41008 IO Biotech, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 87-0 ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) (Address of principal executive offices) (Zip Code) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-41008 IO BIOTECH, INC. (Exact name of Registrant as specified in its Charter) Del ...