Denmark-based clinical-stage biopharmaceutical company IO Biotech (NASDAQ:IOBT) on Monday announced results from its pivotal Phase 3 IOB-013/KN-D18 trial evaluating Cylembio used in combination with Merck & Co Inc 's (NYSE:MRK) anti-PD-1 therapy, KEYTRUDA (pembrolizumab) versus pembrolizumab alone in first-line treatment of advanced melanoma.

The study enrolled 407 patients and met its primary endpoint of progression free survival (PFS) improvement, though statistical significance was narrowly missed (HR 0.77; p=0.056; threshold p≤0.045). Median PFS was 19.4 months for the combined therapy versus 11.0 months for pembrolizumab monotherapy. In patients without prior anti-PD-1 therapy, median PFS reached 24.8 months.

Notable benefit was observed in PD-L1 negative patients, with median PFS of 16.6 months for the combined therapy compared to three months for pembrolizumab alone.

A trend toward overall survival improvement was observed across most subgroups, with data expected to mature within nine months. In addition to this, the combination was well tolerated, with no new safety signals reported.

IO Biotech plans to meet with the US Food and Drug Administration this autumn to discuss a potential Biologics License Application submission.