Moderna and Merck released five‑year interim data from a Phase II trial combining individualized mRNA neoantigen immunotherapy (mRNA‑4157; intismeran autogene) with pembrolizumab in resected high‑risk melanoma. The combination reduced recurrence and death by 49% compared with pembrolizumab alone in the randomized cohort, the companies reported. The personalized mRNA therapy encodes up to 34 patient‑specific neoantigens and is delivered via lipid nanoparticles. Trial investigators sequenced tumors to design bespoke vaccines and administered them alongside the PD‑1 inhibitor to boost tumor‑specific T‑cell responses. The result supports continued development of personalized mRNA immunotherapies in adjuvant oncology. If confirmed in larger pivotal trials, the approach could redefine adjuvant strategies by pairing checkpoint inhibition with individualized vaccines; sponsors will weigh scalability, manufacturing timelines and regulatory pathways for bespoke cancer medicines.