Moderna and Merck report positive Phase 3 results for melanoma mRNA vaccine

A late-stage trial involving 1,137 patients with high-risk melanoma found that the combination of Merck's pembrolizumab (Keytruda) and Moderna's personalized mRNA vaccine, intismeran autogene, delayed cancer recurrence compared with pembrolizumab alone. Participants received surgery to remove visible tumors, then were randomized to receive either Keytruda alone or Keytruda plus up to nine doses of the vaccine every three weeks. The companies said the vaccine met its primary endpoint, showing longer recurrence-free survival and a lower rate of distant metastasis in the combination group.

Intismeran is designed from each patient’s tumor sample to target up to 34 neoantigens, aiming to train the immune system to recognize mutated cancer proteins. Safety findings were consistent with earlier studies, with no new adverse signals reported. The trial has not yet been independently verified, and overall survival data remain immature.

"These Phase 3 findings represent a pivotal moment for the field of cancer research," said Stéphane Bancel, CEO of Moderna.

If regulatory agencies approve the vaccine, it could become the first mRNA-based therapeutic cancer vaccine to reach the market, potentially expanding the use of mRNA technology beyond infectious diseases.