Moderna and Merck Melanoma Vaccine Hits Phase 3 Goals in Historic mRNA Cancer Trial

Moderna and Merck announced Wednesday that their personalized mRNA cancer vaccine, called intismeran autogene, met its primary endpoints in a Phase 3 trial targeting high-risk melanoma, marking the first time a therapy of this kind has succeeded at that stage of testing. The 1,137-patient study enrolled people who had already undergone surgery to remove melanoma, one of the deadliest forms of skin cancer, and tested the vaccine combined with Merck's immunotherapy Keytruda against Keytruda alone. Interim results showed the combination significantly extended the time before cancer returned or spread, though full data have not yet been published in a peer-reviewed journal and will be presented at an upcoming medical meeting.

Moderna CEO Stephane Bancel called the findings a pivotal moment for cancer research, and Merck's Dean Y. Li described them as a landmark. Markets responded dramatically: Moderna shares surged roughly 145%, closing around 154 dollars, after touching an intraday high of 163 dollars, while Merck gained about 10.6% to 149.52 dollars.

Analysts at Mizuho flagged Moderna as having a particular competitive advantage based on the new data. Investors and researchers view the results as potentially opening the door to a broader wave of personalized mRNA cancer vaccines, though analysts cautioned they would await the full dataset before drawing definitive conclusions on efficacy and overall survival, which the trial will continue to assess.