Moderna and Merck published five‑year interim results from the Phase 2 KEYNOTE trial combining personalized mRNA neoantigen therapy intismeran autogene (mRNA‑4157) with pembrolizumab, reporting a 49% reduction in melanoma recurrence and deaths compared with control. The open‑label study randomized patients with high‑risk resectable melanoma and delivered individualized LNP‑formulated mRNA encoding tumor neoantigens alongside anti‑PD‑1 therapy. The outcome strengthens evidence for personalized cancer mRNA vaccines as adjuvant immunotherapy and signals potential for late‑stage development. Sponsors and competitors will watch durability, manufacturing scalability, and regulatory pathways closely; the readout supports continued investment in patient‑specific mRNA oncology programs.