IO Biotech’s off-the-shelf cancer vaccine, Cylembio, narrowly missed the primary endpoint of progression-free survival in a phase 3 melanoma trial but showed encouraging data in patient subgroups and overall survival trends. The combination with Merck’s Keytruda demonstrated earlier and sustained separation of survival curves. Despite the statistical miss, the company plans to engage the FDA to explore regulatory pathways, citing supportive safety data and subgroup benefits. This contrasts with personalized mRNA vaccines in development, positioning Cylembio as a potentially more readily available option.