Merck and Moderna disclosed Phase 3 results showing their personalized mRNA neoantigen vaccine, intismeran autogene, added to Keytruda meaningfully reduced the risk of melanoma recurrence and improved outcomes versus Keytruda plus placebo. The program is designed to prompt patient-specific immune responses against neoantigens derived from tumor sequencing. In the randomized late-stage study, the partners reported statistically significant, clinically meaningful improvements at an interim analysis, while overall survival data remain immature. Merck and Moderna said the trial met its primary endpoint of recurrence-free survival and also reported gains in a secondary endpoint tied to distant metastasis-free survival. The announcement follows Phase 2 data reported earlier this year and positions the combination for regulatory review as a potential new adjuvant option in resected high-risk melanoma. The companies indicated no new safety signals at this point, but full details are expected upon publication.