Personalized mRNA Melanoma Vaccine Intismeran Hits Major Milestone, Cutting Recurrence Risk by 42% in Landmark Phase 3 Trial

Image: Collected

A personalized mRNA cancer vaccine, intismeran autogene, has delivered the first positive Phase 3 result for an mRNA-based cancer therapy, offering new hope for patients with high-risk melanoma.

Developed by Moderna and Merck, intismeran—when combined with the immunotherapy Keytruda (pembrolizumab)—reduced the risk of melanoma recurrence or death by 42% compared with Keytruda alone. The findings come from the pivotal INTerpath-001 trial, presented at the European Society for Medical Oncology (ESMO) Congress 2026.

The study enrolled 1,137 patients with completely resected stage IIB–IV melanoma. After a median follow-up of 24.6 months, 82.2% of patients receiving the vaccine-plus-Keytruda combination were alive without cancer recurrence at two years, compared with 70.0% of those receiving Keytruda alone.

Intismeran is tailored to each patient’s tumor. It uses sequencing data to encode up to 34 tumor-specific neoantigens, effectively teaching the immune system to recognize and attack cancer cells that may remain after surgery.

The treatment also reduced the risk of distant metastasis or death by 38%. At 24 months, distant metastasis-free survival was 88.5% with the combination versus 80.2% with Keytruda alone.

The benefit became even stronger after patients completed the six-month vaccination course. In a pre-specified analysis, the combination reduced the risk of recurrence or death by 58% beyond that point.

Overall survival data remain immature, so researchers say longer follow-up is needed to determine whether the improved recurrence-free survival will translate into longer life. Safety signals were broadly manageable, with grade 3 or higher adverse events reported in 23.6% of patients on the combination versus 20.3% on Keytruda alone.

Moderna and Merck are now preparing regulatory submissions and preparing for a potential commercial launch, subject to approval. The companies are also testing the approach in lung, bladder and kidney cancers.