Merck and Moderna’s mRNA melanoma vaccine cuts recurrence risk by 42% in Phase 3 trial

A Phase 3 study of a personalized mRNA vaccine for melanoma, developed by Merck and Moderna, showed a substantial improvement in patient outcomes.

Patients receiving the vaccine together with Merck’s checkpoint inhibitor Keytruda experienced a 42% lower risk of cancer recurrence or death compared with Keytruda alone.

The data, presented at the European Society for Medical Oncology meeting, represent the first pivotal success for a cancer vaccine in a century of attempts, and scientists say the platform could be adapted to other tumor types.

If regulatory approval follows, the therapy could add a new tool for oncologists treating high‑risk melanoma and may spur further development of mRNA‑based vaccines across oncology.