IO Biotech Halts Cylembio Development

IO Biotech leaves Cylembio, respectively, due to FDA rejection and failure of melanoma trial strain in cash flow and strategy.

IO Biotech has stated it is considering strategic options following the abandonment of its IDO x PD-L1 immunotherapy candidate, Cylembio, which troubled the company during its oncology ambitions in the competitive BioTech marketplace.

This is after the Keynote-D18 first-line melanoma trial did not pass the initial progression-free survival target. Even though the miss occurred, IO Biotech had filed a potential US filing previously and hoped regulatory discussions would pull the program back into life. These plans were actually terminated in September because the FDA recommended the non-submission.

The company had recently, as early as November, scheduled meetings with regulators to discuss the design of a new phase 3 trial. Nonetheless, it had less than $31 million in cash, which could only cover operations through to the first quarter of 2026, a sum insufficient to sustain its operations on an already dubious development route. Lack of good positive regulation feedback has now compelled a redefinition of priorities.

The evolution brings into the limelight more global issues of early-stage BioTech companies attempting to achieve complex immuno-oncology with stricter capital markets. Although, at least temporarily, optimism prevailed following Replimune's success in resubmitting their oncolytic virus therapy, there was no apparent change in regulatory attitude to the good of IO Biotech.

The latest other mRNA-4359 program from Moderna is still in the preclinical stage of development as the third mRNA-IDO x PD-L1 program in phase 1/2 trials. The failure highlights the riskiness of BioTech innovation, where innovation potential is not always successful in both regulatory and commercial terms.