Merck and Moderna mRNA Vaccine Cuts Melanoma Recurrence Risk by 42 Percent

RAHWAY, N.J. — A personalized mRNA cancer vaccine developed by Merck & Co. and Moderna Inc. reduced the risk of melanoma returning or causing death by 42 percent when combined with standard immunotherapy, according to Phase 3 clinical trial results released by the companies.

The late-stage study evaluated the investigational mRNA treatment alongside Keytruda, Merck's anti-PD-1 therapy, in patients with high-risk stage III or stage IV melanoma who had previously undergone surgical resection. Results were compared against patients receiving Keytruda alone, demonstrating a statistically significant improvement in recurrence-free survival.

The experimental vaccine is manufactured individually for each patient using mRNA technology designed to target specific neoantigens derived from the patient's tumor sequencing. The custom therapy aims to train the immune system to recognize and attack distinct cancer mutations.

Adverse events reported during the trial were consistent with previously observed safety profiles for both treatments. Serious treatment-related side effects occurred in a minority of participants, with overall tolerability matching expectations established in earlier phase testing.

Based on the clinical trial outcomes, the drugmakers plan to submit the data to global regulatory authorities to seek approval. Additional trials are also being launched to evaluate the personalized vaccine combination across other cancer types.