Moderna and Merck released five‑year interim results from a personalized mRNA neoantigen therapy (intismeran autogene, mRNA‑4157) combined with pembrolizumab that showed a 49% reduction in melanoma recurrence and deaths in an adjuvant setting. The randomized Phase‑2 KEYNOTE trial enrolled resectable high‑risk melanoma patients and used individualized mRNA constructs encoding each patient’s top neoantigens delivered by lipid nanoparticles. The data highlight the clinical promise of tumor‑specific mRNA vaccines as an adjunct to checkpoint blockade and could accelerate investment and late‑stage planning for personalized cancer immunotherapies. Regulatory and manufacturing scalability questions remain for individualized mRNA products, but the clinical signal offers a strong commercial and scientific validation for the approach.