Melanoma vaccine cuts recurrence risk in phase 3 trial

A personalized melanoma vaccine reduced the risk of melanoma returning or causing death by 42 percent in a phase 3 trial, researchers reported at a European cancer conference this weekend. The melanoma vaccine, called intismeran autogene, was tested together with the immunotherapy drug Keytruda in patients whose melanoma had been removed by surgery. The result was presented at the 2026 European Society for Medical Oncology Congress in Madrid and reported by NPR on October 26, 2026.

The trial, known as INTerpath-001, compared the melanoma vaccine plus Keytruda with Keytruda alone. The immunotherapy drug is the brand name for pembrolizumab, a drug already used in melanoma care. Patients in the trial had high risk melanoma after surgery, a group in which the cancer often returns within the first two years. With The immunotherapy drug alone, about 30 percent of patients relapsed in that period in earlier reports. Adding the melanoma vaccine cut that share to under 20 percent, according to reports of the findings.

The melanoma vaccine is made for each patient. This mRNA cancer vaccine uses messenger RNA, the same type of technology used in some COVID-19 vaccines, to teach immune cells to recognize features of that person's tumor. The approach differs from standard vaccines, which target a virus or a protein shared by many patients. Here, the target is the tumor itself.

How the melanoma vaccine was tested

The melanoma vaccine was developed by Moderna and Merck, working together on the personalized treatment. In the phase 3 trial, patients received the melanoma vaccine alongside pembrolizumab after surgery to remove their melanoma. The control group received pembrolizumab alone. Researchers tracked whether the cancer returned and whether patients died during follow up. The 42 percent reduction covers recurrence or death, the combined measure used as the main result in the trial reports.

Melanoma Institute of Australia medical director Georgina Long presented the results in Madrid. She described the findings as a change in how the immune system can be used in a personal way to lower the risk of melanoma coming back or causing death. The trial supports earlier, smaller studies of the same melanoma vaccine, which had also pointed to a lower recurrence risk when the vaccine was added to pembrolizumab. The skin cancer trial result is the strongest test so far because it enrolled a larger group and compared the combination directly with standard immunotherapy alone.

What the melanoma vaccine results mean for patients

For patients, the the vaccine result matters because recurrence after surgery is the main worry in high risk melanoma. Surgery can remove the visible tumor, but microscopic cancer cells can remain and grow later. Immunotherapy with The immunotherapy drug already lowers that risk for many patients. The new data suggest that adding a the vaccine tailored to each tumor can lower it further. That could mean more patients stay free of cancer for longer after their operation.

Still, the skin cancer trial has drawn wide attention because it is the first phase 3 test of a personalized mRNA cancer vaccine to show this size of benefit. Other personalized vaccines are in testing for other cancers, but no other mRNA cancer vaccine has reached this stage with a comparable result in a large randomized trial, and no other skin cancer trial has reported this size of benefit. If later reviews confirm the finding, the same method could be tested more widely in cancers where surgery leaves a high risk of return.

What happens next for the the vaccine

The next step for the the vaccine is regulatory review, using the full data from INTerpath-001. The companies have not announced a filing date in the reports of the weekend presentation. Doctors will also look for longer follow up to see whether the lower recurrence rate holds over more years, and whether the benefit applies across patient subgroups. Safety data from the trial will be part of that review, since the vaccine is given with an immunotherapy drug that can cause immune related side effects on its own.

Patients with melanoma should talk with their treating team about trial options and approved treatments, since the the vaccine is not yet a standard option outside a trial. For now, the phase 3 result gives researchers a concrete reason to keep testing personalized vaccines, and it gives patients with high risk melanoma a reason to watch the regulatory process closely as the full data are published and reviewed.