IO Biotech has resorted to halving its workforce after the FDA knocked back its plans to seek approval for its cancer vaccine.
The therapeutic vaccine, called Cylembio, failed to beat Merck & Co.’s Keytruda in a phase 3 melanoma trial last month. Undeterred by the top-line failure—and pointing to a “trend toward an improvement” in the incoming overall survival data—IO said at the time that it still planned to head to the FDA in the fall “to discuss the totality of data” and determine next steps for submitting an approval application.
Now, the word has come through from the regulator, and it’s not what IO wanted to hear. When it comes to an approval application based on data from the failed phase 3 study, the FDA has recommended that IO not bother.
“We had a productive meeting with FDA; while this is not the outcome we had hoped for, we respect FDA’s feedback and remain confident in the therapeutic potential of Cylembio,” IO CEO Mai-Britt Zocca, Ph.D., said in a Sept. 29 release.
“We look forward to continuing the dialogue with FDA to align on the design for a potential new registrational study,” Zocca added. “Additionally, we plan to discuss the data from our IOB-013 study with European regulators and determine a path to submission in the EU.”
As the company works out a route around today’s setback, IO announced that half of the company’s workforce won’t be joining it on the next stage of the regulatory journey. With IO’s cash due to run out in the first quarter of 2026, the layoffs are needed as part of a “plan to conserve capital while [IO] pursues a pathway to regulatory approval for Cylembio and works to complete ongoing studies.”
Unlike high-profile personalized cancer vaccines being developed by mRNA companies Moderna and BioNTech, Cylembio is a combination of two off-the-shelf vaccines derived from IO’s T-win platform. The aim is to stimulate T cells against tumor cells in the tumor microenvironment.
IO has touted the platform as having a “highly differentiated mechanism of action [that] has demonstrated clinical activity without additional significant systemic toxicity when administered in combination with an approved anti-PD-1 therapy.”