Moderna and Merck's personalised mRNA vaccine cuts melanoma recurrence risk by 42% in late-stage trial

Moderna and Merck have released detailed phase 3 results for intismeran autogene, their personalised mRNA vaccine, in the INTerpath-001 trial (NCT05933577): added to Keytruda, it cut the risk of melanoma recurrence or death by 42% and of distant metastasis or death by 38% versus Keytruda alone. Released on Thursday after an oncology-website leak; August’s announcement said the trial met its primary and key secondary endpoints.

The trial enrolled 1,137 patients with high-risk, completely resected stage IIB–IV melanoma, randomised 2:1 to vaccine plus pembrolizumab or placebo plus pembrolizumab. At a median 24.6 months, two-year recurrence-free survival was 82.2% versus 70.0%; overall survival is not yet mature, though a “favourable trend” was reported.

“This new vaccine is something that we’ve never really seen before in terms of the efficacy that it has demonstrated,” Dr Michael Postow told CNN. “The field has been looking for a win and I think this one is a big one,” said Dr Hussein Tawbi.

Side effects were mainly a sore arm and fatigue, typical of mRNA Covid jabs; each dose takes about six weeks to brew at Moderna’s Massachusetts facility. The results are accepted by The New England Journal of Medicine and due to be presented on Saturday at ESMO’s Presidential Symposium I in Madrid. The companies are engaging regulators; RBC expects possible FDA approval next year (CNN). Moderna shares sank over 25% on Thursday — the steepest one-day fall on record, about $24bn wiped — after a rally of over 500% this year: a “sell-the-news” reaction.

Sources

• Reuters — Moderna sheds about $24 billion as cancer vaccine data triggers ‘sell-the-news’ retreat — https://www.reuters.com/business/healthcare-pharmaceuticals/moderna-sheds-about-24-billion-cancer-vaccine-data-triggers-sell-the-news-2026-10-22/
• CNN — Experimental mRNA vaccine cuts risk melanoma returns by 42% — https://www.cnn.com/2026/10/22/health/mnra-cancer-vaccine-moderna?cid=external-feeds_iluminar_meta
• Scientific American — Here’s what Moderna’s latest mRNA cancer vaccine data actually show — https://www.scientificamerican.com/article/heres-what-modernas-latest-mrna-cancer-vaccine-data-actually-show/
• AJMC — Merck, Moderna Cancer Vaccine Cuts Melanoma Recurrence Risk by 42% — https://www.ajmc.com/view/merck-moderna-cancer-vaccine-cuts-melanoma-recurrence-risk-by-42-
• Gulf News (AP) — Novel mRNA cancer vaccine helps reduce chances of melanoma patients’ tumours returning — https://gulfnews.com/world/americas/novel-mrna-cancer-vaccine-helps-reduce-chances-of-melanoma-patients-tumours-returning-1.500720463