08:52 AM EDT, 08/11/2025 (MT Newswires) -- IO Biotech ( IOBT ) said Monday that its cancer vaccine candidate cylembio, combined with Merck's ( MRK ) pembrolizumab, demonstrated improved progression-free survival compared with pembrolizumab alone in a phase 3 trial evaluating the combination in patients with advanced melanoma.

Patients treated with the combination of cylembio and pembrolizumab exhibited a median progression-free survival of 19.4 months, compared with 11 months in individuals who were given pembrolizumab, IO Biotech ( IOBT ) said. The company said that primary endpoint results narrowly missed statistical significance.

The company also said that a trend towards improvement in overall survival was also observed, but noted the data was still not mature.

IO Biotech ( IOBT ) plans to meet with the US Food and Drug Administration to discuss the data and next steps for a potential regulatory submission this fall, it said.

Shares of IO Biotech ( IOBT ) were down 7% in recent Monday premarket activity.