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 ...