Merck & Moderna’s Personalized mRNA Vaccine Sustains 49% Risk Reduction in Melanoma at Five Years

CAMBRIDGE, Mass. & RAHWAY, N.J.— January 20, 2026— In a landmark update for the oncology sector, Moderna and Merck (known as MSD outside the U.S.) have released five-year follow-up data from the Phase IIb KEYNOTE-942 trial. The results show that the combination of intismeran autogene (mRNA-4157/V940) and Keytruda continued to reduce the risk of recurrence or death by 49% (HR=0.51) in patients with resected high-risk melanoma compared to Keytruda alone.

The data represents a critical “maintenance of effect,” as the 49% risk reduction reported at the five-year mark remains identical to the results seen at three years. Analysts from William Blair noted that this stability suggests the personalized vaccine successfully reprograms the adaptive immune system for long-term surveillance. For patients with stage III/IV melanoma—who face high recurrence rates even after successful surgery—this durable five-year window is widely considered a “functional milestone” for potential cure.

Intismeran autogene is a bespoke individualized neoantigen therapy (INT). Each dose is custom-manufactured by sequencing a patient’s unique tumor to identify up to 34 neoantigens, which are then encoded into a synthetic mRNA strand. When administered alongside Keytruda, the vaccine provides the “GPS coordinates” for the immune system, while the checkpoint inhibitor releases the “brakes,” enabling a precision attack on any remaining microscopic cancer cells.

The companies are now looking toward 2026/2027 as a transformative period for the platform. A global Phase III trial (INTerpath-001) in adjuvant melanoma is already fully enrolled, with interim data potentially expected later this year. Beyond skin cancer, the partnership is aggressively expanding into other high-unmet-need areas, including ongoing Phase III studies in non-small cell lung cancer (NSCLC) and Phase II trials in renal cell and bladder cancers.