Moderna-Merck personalized melanoma vaccine cuts recurrence risk by 42% in late-stage trial

A personalized mRNA vaccine from Moderna and Merck, given alongside Keytruda after surgery, lowered the risk of high-risk melanoma returning within two years by 42% in a trial of more than 1,100 patients.

A personalized cancer vaccine developed by Moderna and Merck reduced the risk of melanoma returning two years after surgery by 42% when added to standard treatment, according to results of a late-stage trial released on Thursday.

The study enrolled more than 1,100 people with high-risk melanoma that had been surgically removed. All received Merck's immunotherapy Keytruda and were randomly assigned to also get the custom vaccine, called intismeran, or a placebo. After two years, 82% of those who received the vaccine had no recurrence, compared with 70% of those on Keytruda alone.

MD Anderson Cancer Center in Houston

Each vaccine is built from mutations unique to a patient's tumor and is given in nine doses three weeks apart, training the immune system to attack abnormal proteins created by those mutations. The full process, from genetic analysis of the tumor to a finished vaccine, takes about six weeks, according to Moderna President Stephen Hoge.

"The field has been looking for a win and I think this one is a big one," said Dr. Hussein Tawbi of MD Anderson Cancer Center in Houston, an investigator in the study. Side effects were mostly a sore arm and fatigue, similar to COVID-19 vaccination. The companies are discussing regulatory approval with authorities and have not disclosed a price. Detailed results are set to be presented at the European Society for Medical Oncology meeting in Madrid.