IO Biotech shares surge 26.75% after-hours on positive Cylembio Phase 3 trial results showing improved progression-free survival in melanoma.

IO Biotech, Inc. (IOBT) surged 26.75% in after-hours trading following the presentation of updated Phase 3 trial results for Cylembio at the Jefferies Global Healthcare Conference. The trial demonstrated a median progression-free survival of 19.4 months for Cylembio versus 11.0 months for pembrolizumab alone in advanced melanoma patients, with no significant added systemic toxicity. The data highlighted a $5.6 billion U.S. market opportunity and plans to align with the FDA on a new Phase 3 design. These positive clinical and commercial signals drove the sharp after-hours rally, overshadowing earlier analyst concerns about the company’s financial instability.