IO Biotech Presents New Data at AACR 2024 Further Supporting Dual Mechanism of Action of Lead Cancer Vaccine, IO102-IO103

IO Biotech (Nasdaq: IOBT), a clinical-stage biopharmaceutical company developing novel, immune-modulating therapeutic cancer vaccines based on its T-win® platform, today shared new data related to the company’s lead therapeutic cancer vaccine candidate, IO102-IO103, at the American Association for Cancer Research (AACR) Annual Meeting 2024, taking place April 5-10, 2024, in San Diego, California.

“These data build on earlier studies that demonstrated the mechanism of IO102 and IO103,” said Mai-Britt Zocca, Ph.D., President and CEO of IO Biotech. “We now clearly see that used together, IO102-IO103 create an environment in and around the tumor that allow for enhanced anti-tumor activity, at a much greater level than either could do on its own. With this additional data, we further understand the mechanistic rationale for the clinical effect observed in the Phase 1/2 study of IO102-IO103 that we hope to confirm in our ongoing Phase 3 pivotal study.”

The data presented in the AACR poster are from two different animal tumor models and show that vaccines targeting IDO1 and PD-L1 expressing cells can cooperatively reduce tumor growth with each contributing to the anti-tumor effect through distinct molecular pathways. Where high levels of IDO1 and PD-L1 expression were seen in the tumor microenvironment (TME), the IDO1 vaccine predominantly reduced myeloid-derived immune suppression, while the PD-L1 vaccine enhanced anti-tumor T-effector functions. In contrast, where IDO1 and PD-L1 expression was lower, the IDO1 vaccine resulted in a clear increase in T cell infiltration and activation and the PD-L1 vaccine impacted the myeloid cell compartment. While further studies are needed to fully discern the relationship between IDO1+/PD-L1+ target populations within the TME and the impact of IDO1/PD-L1 targeted vaccination, our data support the use of a dual antigen approach to reduce the immunosuppression and enhance anti-tumor effect.

The poster can be found on the “Posters & Publications” page of the IO Biotech website and on the AACR website. Details for the presentation are below:

Title: Immune modulatory cancer vaccines against IDO1 and PD-L1 trigger distinct pathways and cooperatively reduce tumor growth in preclinical models Abstract Number: 4094Time: Tuesday, April 9, 2024 9:00 AM - 12:30 PM PTPresenter: Marion Chapellier, Ph.D., Senior Scientist R&D and translational research

About IO102-IO103

IO102-IO103 is an investigational, off-the-shelf therapeutic cancer vaccine designed to kill both tumor cells and immune-suppressive cells in the tumor microenvironment (TME) by stimulating activation and expansion of T cells against indoleamine 2,3-dioxygenase (IDO) and/or programmed death-ligand 1 (PD-L1) cells. The company is currently conducting a pivotal Phase 3 trial (IOB-013/KN-D18; NCT05155254) investigating IO102-IO103 in combination with pembrolizumab versus pembrolizumab alone in patients with advanced melanoma, a Phase 2 basket trial (IOB-022/KN-D38; NCT05077709) investigating IO102-IO103 in combination with pembrolizumab as first line treatment in patients with solid tumors, and a Phase 2 basket trial (IOB-032/PN-E40; NCT05280314) investigating IO102-IO103 in combination with pembrolizumab as neo-adjuvant/adjuvant treatment of patients with solid tumors.

The clinical trials are sponsored by IO Biotech and conducted in collaboration with Merck, and Merck is supplying pembrolizumab. IO Biotech maintains global commercial rights to IO102-IO103.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

About the IOB-013/KN-D18 Pivotal Phase 3 Clinical Trial

IOB-013/KN-D18 (Clinical Trials.gov: NCT05155254) is an open label, randomized Phase 3 clinical trial of IO102-IO103 in combination with pembrolizumab versus pembrolizumab alone in patients with previously untreated, unresectable or metastatic (advanced) melanoma, being conducted in collaboration with Merck. Patients have been enrolled from centers across the United States, Europe, Australia, Turkey, Israel and South Africa. The primary endpoint of the study is progression free survival. Biomarker analyses will also be conducted. IO Biotech is sponsoring the Phase 3 trial and Merck is supplying pembrolizumab. IO Biotech maintains global commercial rights to IO102-IO103.

About IO Biotech

IO Biotech is a clinical-stage biopharmaceutical company developing novel, immune-modulating therapeutic cancer vaccines based on its T-win® platform. The T-win platform is based on a novel approach to cancer vaccines designed to activate T cells to target the immunosuppressive cells in the tumor microenvironment. IO Biotech is advancing its lead cancer vaccine candidate, IO102-IO103, in clinical trials, and additional pipeline candidates through preclinical development. Based on positive Phase 1/2 first line metastatic melanoma data, IO102-IO103, in combination with pembrolizumab, has been granted a breakthrough therapy designation for the treatment of advanced melanoma by the US Food and Drug Administration. IO Biotech is headquartered in Copenhagen, Denmark and has US headquarters in New York, New York.

For further information, please visit www.iobiotech.com. Follow us on our social media channels on LinkedIn and X (@IOBiotech).

Forward-Looking Statement

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements, including regarding the timing of the interim and primary analyses of the company’s Phase 3 trial, current or future clinical trials, their progress, enrollment or results, or the company’s financial position or cash runway, are based on IO Biotech’s current assumptions and expectations of future events and trends, which affect or may affect its business, strategy, operations or financial performance, and actual results and other events may differ materially from those expressed or implied in such statements due to numerous risks and uncertainties. Forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified. Because forward-looking statements are inherently subject to risks and uncertainties, you should not rely on these forward-looking statements as predictions of future events. These forward-looking statements speak only as of the date hereof and should not be unduly relied upon. Except to the extent required by law, IO Biotech undertakes no obligation to update these statements, whether as a result of any new information, future developments or otherwise.

Contact:Maryann Cimino, Director of Investor Relations IO Biotech, [e-mail]