FDA Rejects BLA for IO Biotech's Cylembio, Plans New Registrational Study

IO Biotech provided an update on the regulatory pathway for Cylembio after a pre-BLA meeting with the FDA. The FDA recommended against a BLA based on the IOB-013 trial results, which showed improved PFS but narrowly missed statistical significance. IO Biotech plans to continue dialogue with the FDA to align on a potential new registrational study. Enrollment in two Phase 2 clinical trials is complete.

IO Biotech (Nasdaq: IOBT), a clinical-stage biopharmaceutical company, has received a setback from the U.S. Food and Drug Administration (FDA) regarding its therapeutic cancer vaccine candidate, Cylembio. The FDA has advised against a Biologics License Application (BLA) submission based on data from the IOB-013 clinical trial, which showed improved progression-free survival (PFS) when Cylembio was combined with pembrolizumab, but the results did not achieve statistical significance.

The company plans to design a new registrational study and continue discussions with the FDA, while also seeking feedback from European regulators. To conserve capital during this period, IO Biotech is restructuring its operations with a workforce reduction of approximately 50 percent. The company aims to maintain operations through early 2026 and will incur restructuring charges of $1.0 to $1.5 million in Q3 2025.

The FDA's recommendation indicates significant regulatory challenges for the company. The restructuring and workforce reduction may disrupt operations and morale. The anticipated non-recurring charge of $1.0 - $1.5 million may strain the company's financial position during a crucial time of pursuing further studies.

IO Biotech maintains ongoing collaborations with Merck for pivotal trials, which can enhance credibility and support for future studies. The company's commitment to transparency about its clinical developments is evident in the topline results from the IOB-013 trial.

IO Biotech is conducting a Phase 3 trial in advanced melanoma and two Phase 2 trials in solid tumors with Cylembio. Enrollment in these trials is complete, indicating the company's progress in advancing its lead cancer vaccine candidate.