Interim five‑year data from a randomized Phase II trial show that combining Moderna’s personalized neoantigen mRNA candidate (mRNA‑4157/intismeran autogene) with pembrolizumab reduced melanoma recurrence and deaths by about 49% versus pembrolizumab alone. The trial tested patient‑customized mRNA encoding up to dozens of tumor neoantigens delivered in lipid nanoparticles alongside standard PD‑1 blockade. Investigators sequenced tumor neoantigens for each patient and manufactured individualized mRNA therapies, aiming to prime T‑cell responses against residual disease after resection. The result provides clinical proof‑of‑concept for personalized neoantigen mRNA immunotherapy in the adjuvant setting and could accelerate pivotal plans if durability and safety hold in larger studies.