IO Biotech (NASDAQ:IOBT) stock gained 6.1% after revealing topline data from its pivotal Phase 3 trial evaluating Cylembio, an experimental cancer vaccine, combined with Merck’s (NSE:PROR) KEYTRUDA in patients with advanced melanoma.
The study demonstrated clinical benefits in progression-free survival (PFS) for the combination treatment versus KEYTRUDA alone, though it narrowly fell short of statistical significance on its primary endpoint. Patients receiving both therapies experienced a median PFS of 19.4 months compared to 11.0 months for those on KEYTRUDA monotherapy, with a hazard ratio of 0.77.
A particularly striking result was seen in patients with PD-L1 negative tumors, where the combined treatment yielded a median PFS of 16.6 months, markedly higher than the 3.0 months seen with KEYTRUDA alone. The regimen was generally well-tolerated and raised no new safety concerns.
“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 engage with the FDA this fall to explore the potential filing of a Biologics License Application based on these outcomes. While overall survival data remain immature, early indicators suggest the combination therapy may offer benefits across multiple patient groups.
IO Biotech also intends to share more comprehensive findings from the trial at an upcoming medical conference.
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