Merck and Moderna announced Phase 3 success for their personalized neoantigen mRNA vaccine intismeran autogene in adjuvant melanoma, reporting a statistically significant improvement in reducing recurrence and distant spread when added to Keytruda. The companies said the trial met its primary endpoint of recurrence-free survival and a secondary endpoint of distant metastasis-free survival at an interim analysis. The program is designed to stimulate immunity against patient-specific tumor neoantigens using an autogene approach. Patients in the pivotal study had cutaneous melanoma resected and were randomized to receive Keytruda plus placebo or Keytruda plus the individualized vaccine, with the study continuing to evaluate additional endpoints including overall survival. The result follows earlier skepticism around whether personalized neoantigen vaccines could scale beyond proof-of-concept in randomized settings. If further data and safety reporting align with expectations, the trial could validate a platform that integrates Big Pharma checkpoint therapy with tailored mRNA immunotherapy.