IO Biotech stock rises as cancer vaccine shows promising results

Published 11/08/2025, 14:14
© Reuters.

Investing.com -- IO Biotech (NASDAQ:IOBT) stock rose 6.1% after announcing topline results from its pivotal Phase 3 trial of Cylembio, an investigational cancer vaccine, in combination with Merck (NSE:PROR)’s KEYTRUDA for advanced melanoma patients.

The trial showed clinical improvement in progression-free survival (PFS) compared to KEYTRUDA alone, though it narrowly missed statistical significance on the primary endpoint. Patients treated with the combination achieved 19.4 months of median PFS versus 11.0 months for those on KEYTRUDA monotherapy, with a hazard ratio of 0.77.

Particularly notable was the effect in PD-L1 negative tumor patients, where the combination therapy demonstrated median PFS of 16.6 months compared to just 3.0 months with KEYTRUDA alone. The combination was well-tolerated with no new safety concerns identified.

"In this study, patients treated with Cylembio in combination with pembrolizumab have achieved the longest median PFS ever observed in a Phase 3 clinical study in advanced melanoma," said Omid Hamid, Director of Clinical Research and Immunotherapy at The Angeles Clinic and Research Institute.

The company plans to meet with the FDA this fall to discuss potential submission of a Biologics License Application based on these results. While overall survival data is not yet mature, early trends show improvement favoring the combination therapy across multiple patient subgroups.

IO Biotech intends to present more detailed results from the study at an upcoming medical meeting.

This article was generated with the support of AI and reviewed by an editor. For more information see our T&C.

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