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# FDA Tells IO Biotech to Delay Cancer Vaccine Filing
- URL: https://www.fdaweb.com/fda-tells-io-biotech-to-delay-cancer-vaccine-filing/
- Published: 2025-09-29T12:00:00.000Z
- Updated: 2026-09-14T15:22:52.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5159954

IO Biotech says it has recently been advised by FDA not to submit a BLA for its experimental cancer vaccine Cylembio based on results from a recently completed Phase 3 trial in advanced melanoma. The FDA input came during a pre-BLA meeting at which the agency concluded that data from the IOB-013 trial — where Cylembio plus Merck’s Keytruda improved progression-free survival but narrowly missed statistical significance — were not sufficient to support a filing. As a result, the company plans to design a new registrational trial for Cylembio in first-line advanced melanoma.

Cylembio is described by the company as an investigational immune-modulatory vaccine designed to stimulate T cells to target both tumor cells and immune-suppressive cells in the tumor microenvironment. The company, in collaboration with Merck, continues to evaluate the therapy in other Phase 2 trials for advanced solid tumors and in the adjuvant setting.