Long‑term data show that adding Merck’s Keytruda to Moderna’s personalized neoantigen cancer vaccine sustained a roughly 49% reduction in risk of recurrence or death at five years, the companies reported. The follow‑up strengthens the vaccine’s clinical signal after earlier readouts and supports ongoing Phase III planning and regulatory discussions. The trial combined an mRNA‑based personalized vaccine with anti‑PD‑1 therapy to enhance tumor‑specific immunity; personalized neoantigen vaccines use sequencing of a patient’s tumor to design individualized mRNA immunogens. The five‑year durability of effect was highlighted by industry analysts as evidence of durable tumor control and as reinforcing the commercial outlook for combination immunotherapies. Companies emphasized the role of long‑term follow‑up in confirming durability for immuno‑oncology combos and noted next steps include confirmatory studies and regulatory engagement. The result is likely to shape development strategies for other personalized cancer vaccine efforts across the sector.