A personalized mRNA vaccine developed jointly by US drugmakers Merck and Moderna has shown potential to significantly reduce the risk of melanoma returning after surgery. The vaccine is given alongside Merck’s immunotherapy drug Keytruda, with researchers saying the approach could eventually open new treatment options for other tumors and cancers.

In a large study involving more than 1,000 melanoma patients, participants received up to nine doses of the personalized vaccine every six weeks after surgery, together with Keytruda. Five-year data from earlier research showed that adding the vaccine reduced the risk of cancer recurrence by about 50 percent and the risk of spread to other parts of the body by about 59 percent compared with Keytruda alone.

Researchers reported no new significant harmful side effects from combining the vaccine with Keytruda. Merck and Moderna are also testing the technology for non-small cell lung cancer, while studies are under way for bladder, kidney, pancreatic and stomach cancers. Some results from those trials may be available within one to two years.