Moderna's personalized mRNA melanoma vaccine cuts cancer recurrence risk by half in five-year trial results

Jun 1, 2026

Five-year trial results show Moderna's personalized mRNA vaccine, intismeran, when combined with Merck's immunotherapy drug Keytruda, cuts the risk of melanoma recurrence or death by 49%. In the 157-patient study, 68.8% of patients on the combination therapy remained cancer-free, versus 49.1% on Keytruda alone. A larger Phase 3 trial is underway as the companies move toward seeking FDA approval.

Personalized mRNA melanoma vaccine trial

▪The five-year results were presented on June 1, 2026, at the American Society of Clinical Oncology’s annual meeting and published in the Journal of Clinical Oncology.
▪The trial was funded by Moderna and a subsidiary of Merck, which manufactures Keytruda.
▪A clinical trial of Moderna's personalized mRNA vaccine, intismeran, involved 157 patients in the U.S. and Australia with high-risk melanoma who had undergone surgery.
▪The trial compared patients receiving the vaccine combined with the immunotherapy drug Keytruda against patients receiving Keytruda alone.

Tumor-specific vaccine personalization process

▪In the trial, it took four to six weeks to create each personalized vaccine after surgery, and patients received up to nine doses.
▪Each vaccine is personalized by sequencing a patient's tumor to identify and encode up to 34 unique molecular targets called neoantigens.
▪The mRNA vaccine trains the immune system's T-cells to recognize and attack the specific neoantigens on a patient's cancer cells.

Five-year survival outcomes

▪After five years, 68.8% of patients receiving the combination therapy were cancer-free, compared to 49.1% of those who received only Keytruda.
▪The combination of the mRNA vaccine and Keytruda reduced the risk of melanoma recurrence or death by 49% over five years compared to Keytruda alone.
▪Adding the vaccine to treatment reduced the risk of the cancer metastasizing, or spreading to other parts of the body, by 59%.
▪The five-year overall survival rate was 92% for patients in the combination therapy group, versus 71% for those in the Keytruda-only group.

Keytruda immunotherapy combination

▪Side effects from the combination therapy were generally mild, including flu-like symptoms such as chills, headaches, and minor pain at the injection site.
▪The immunotherapy drug Keytruda (pembrolizumab) works by helping the immune system's T-cells recognize and attack cancer cells that would otherwise be hidden.

Phase 3 trial FDA pathway

▪Moderna and Merck intend to seek FDA approval for the vaccine, named intismeran, after the Phase 3 trial results are analyzed.
▪A larger Phase 3 trial of the vaccine is now underway, involving nearly 1,000 patients and expanding to Europe.
▪Researchers are also studying whether mRNA vaccines can be used to prevent the recurrence of other cancers, including lung cancer.