Merck and Moderna reported positive results from a randomized Phase 3 study of their personalized mRNA neoantigen vaccine, intismeran autogene, in combination with Keytruda for resected high-risk melanoma. The companies said the trial met its primary endpoint and showed a statistically significant improvement in recurrence-free survival alongside improved distant metastasis-free survival. The program is part of a long-running partnership in which Moderna builds individualized mRNA cancer vaccines based on a patient’s tumor neoantigen profile, paired with Merck’s anti–PD-1 immunotherapy. The companies characterized results as both statistically significant and clinically meaningful at an interim analysis, while noting overall survival follow-up remains immature. The Phase 3 readout extends investor and clinical focus on whether personalized mRNA vaccines can translate into broad, practice-changing oncology utility beyond other mRNA oncology successes.