Personalized mRNA Cancer Vaccine Cuts Melanoma Recurrence Risk by 42% in Phase III Trial

A Phase III trial showed that intismeran autogene, a personalized mRNA therapy, combined with pembrolizumab, reduced the risk of death or recurrence by 42% in high-risk melanoma patients. The study, presented at ESMO 2026, enrolled 1,137 patients and demonstrated improved recurrence-free and distant metastasis-free survival. Despite the positive clinical results, a data leak caused shares of manufacturers Moderna and Merck to fall.

Merck and Moderna's Phase 3 trial showed a 42% reduction in melanoma recurrence or death risk when combining their mRNA vaccine with Keytruda. The trial involved 1,137 patients with high-risk melanoma. Overall survival data is pending. The vaccine is not yet approved, and commercial success is uncertain. Moderna aims for approval in 2025.

Moderna and Merck reported that their cancer vaccine, combined with Merck's Keytruda, reduced melanoma death and recurrence risk by 42% in a trial of 1,100 patients. The results, based on two-year data, will be presented at the European Society for Medical Oncology meeting. Analysts expected a 40%+ risk reduction.

Moderna's stock fell over 1% after Phase 3 melanoma vaccine trial data showed a 42% reduction in recurrence or death risk. Analysts had mixed reactions, with price targets ranging from $80 to $137. The trial, conducted with Merck, involved 1,137 participants and reported side effects like fever and fatigue. Full data will be presented at a cancer conference in Madrid.

Moderna and Merck's Phase 3 trial of personalized melanoma vaccine intismeran autogene with Keytruda showed a 42% reduction in recurrence or death risk vs. Keytruda alone. Two-year recurrence-free survival was 82.2% for the combination vs. 70.0% for Keytruda alone. The combination had more adverse events. Specialists called results clinically meaningful but not yet establishing longer life. Moderna shares fell 17.57% following the release.

Moderna (MRNA) reported Phase 3 results showing its melanoma combo vaccine with Keytruda reduced recurrence/death risk by ~42% and distant metastasis by ~38%. The EU and FDA approved other Moderna vaccines. Analysts had mixed reactions: Citi reiterated a Sell rating, Bernstein maintained Market Perform with a $45 target, and TD Cowen kept Hold with a $90 target. MRNA stock showed volatility.