Merck and Moderna reported Phase 3 success for their personalized mRNA cancer vaccine, intismeran autogene, in adjuvant melanoma when combined with Merck’s Keytruda. The companies said the trial met its primary endpoint for slowing recurrence and disease spread, setting up a potential next regulatory push for neoantigen vaccination in earlier-stage treatment settings. The Phase 3 readout strengthens the case for individualized “neoantigen” vaccines and adds randomized late-stage evidence aimed at settling efficacy questions that earlier studies have struggled to resolve. The companies did not immediately release the full dataset, but the announcement is expected to influence how developers prioritize similar mRNA vaccine platforms. The trial design—personalized vaccination plus continued checkpoint therapy after surgical resection—also highlights an emerging combo strategy in immuno-oncology: pairing tumor-targeted vaccination with established systemic immunotherapy rather than attempting stand-alone immunization.