A personalized cancer vaccine combined with standard immunotherapy reduced the risk of melanoma recurrence or death by 42% compared with immunotherapy alone, according to results from a phase 3 trial involving 1,137 patients.
The trial tested intismeran autogene, an mRNA vaccine developed by Moderna and Merck, alongside pembrolizumab. Participants had surgery to remove high-risk melanoma before treatment. At two years, 82.2% of those given the combination were alive without their cancer returning, compared with 70% of patients who received pembrolizumab and a placebo.
A vaccine designed around each tumor
Researchers analyzed each patient's tumor and healthy tissue to identify mutations that could produce recognizable cancer markers, known as neoantigens. The vaccine was then tailored to encode up to 34 selected targets, helping the immune system learn to identify cancer cells that may remain after surgery. Pembrolizumab supports this response by blocking a signal tumors can use to weaken immune activity.
After a median follow-up of 24.6 months, the combination also showed an advantage in preventing melanoma from spreading to distant parts of the body. Researchers have not yet established whether the treatment improves overall survival, and follow-up is continuing.
The findings come from a large randomized phase 3 trial, following earlier encouraging results. However, each vaccine must be individually designed and manufactured, and its availability will depend in part on regulatory review and the ability to deliver personalized treatment at scale.
If further research confirms its benefits, this approach could help bring precision medicine into post-surgery cancer care and inform tailored vaccines for other cancer types.
