Moderna and Merck’s Phase 3 melanoma results for the personalized mRNA vaccine intismeran autogene—paired with Keytruda—showed a 42% reduction in risk of recurrence or death versus Keytruda alone after a median follow-up of about two years. The study reported an additional 38% reduction in risk of metastatic spread or death. The data, which were accepted for publication in the New England Journal of Medicine, also highlighted substantially higher non-relapse rates: 82.2% in the combination arm versus 70% with Keytruda alone at two years. Overall survival was not yet mature, with follow-up still ongoing. Market reaction followed the disclosure quickly. Analysts and market participants pointed to adoption questions—including personalized manufacturing logistics—while investors weighed the strength of the effect against what had already been priced into expectations for next-generation mRNA oncology. Moderna and Merck said they are engaging with regulators as they seek approval based on the recurrence endpoints, with additional survival and patient-reported outcomes expected later.