A novel personalized mRNA vaccine has been shown to significantly reduce the risk of melanoma recurrence when added to standard post-surgical treatment, according to results from an international clinical trial conducted by Moderna and Merck. The findings, released on October 27 and presented at the European Society of Medical Oncology meeting in Madrid, represent a major advancement in cancer immunotherapy.
The vaccine, named intismeran, is tailored to each patient’s tumor by identifying unique gene mutations that produce neoantigens—proteins that the immune system can be trained to recognize and attack. This approach employs mRNA technology similar to that used in some COVID-19 vaccines. Patients received nine doses of the vaccine administered three weeks apart alongside standard immunotherapy with Merck’s Keytruda.
The phase 3 trial enrolled over 1,100 patients with high-risk melanoma that had been surgically removed. After two years, 82% of the patients receiving intismeran remained free of recurrence, compared with 70% in the group receiving only Keytruda. This equates to a 42% reduction in the risk of the cancer returning. The study continues to monitor longer-term outcomes.
“This is a new frontier,” said Karen Knudsen, CEO of the Parker Institute, which funds cancer immunotherapy research. Experts not involved in the trial noted that the data represents an important step forward for oncology, as the personalized vaccine approach could potentially be adapted for other cancers, including lung, kidney, and pancreatic tumors.
Dr. Hussein Tawbi of the MD Anderson Cancer Center in Houston, a lead researcher on the study, described the results as a significant breakthrough for the field. Personal accounts of patients undergoing the treatment underscore its promise. Tony Hout, 62, from Cayuga, Indiana, joined the trial after melanoma was diagnosed on his ear and found to have begun spreading. Following surgery and the vaccine regimen, his recent scans show no signs of cancer.
Unlike vaccines that prevent infections, such as the HPV and hepatitis B vaccines which reduce cancer risk by blocking viruses, intismeran is designed to help prevent cancer from returning after surgery by priming the immune system against the tumor’s specific mutated proteins. Researchers emphasize that this personalized approach could mark a new phase in cancer treatment, providing targeted immune surveillance to halt disease progression.
Moderna and Merck had initially announced positive trial results in August, but the detailed data release was timed with the scientific conference. Some information was inadvertently disclosed ahead of schedule, prompting the companies to make the full findings public in advance of the meeting.