A personalised mRNA vaccine developed jointly by Merck and Moderna has shown promising results in reducing the risk of melanoma returning after surgery, raising hopes for a new approach to cancer treatment.In a large-scale trial involving more than 1,000 melanoma patients, participants received up to nine doses of the personalised vaccine at six-week intervals along with Merck’s immunotherapy drug Keytruda following surgery.According to five-year follow-up data, adding the vaccine to Keytruda reduced the risk of cancer recurrence by about 50 percent and the risk of the disease spreading to other parts of the body by nearly 59 percent, compared with Keytruda alone.The vaccine is designed to identify specific genetic changes in a patient’s tumour and train the immune system to target cancer cells carrying those changes.Researchers said no significant new safety concerns emerged from combining the vaccine with Keytruda. Most vaccine-related reactions were similar to the mild symptoms commonly seen after flu or COVID-19 vaccinations.Trials are also underway to explore the technology in other cancers, including lung, bladder, kidney, pancreatic and stomach cancers. Roche and BioNTech are separately testing mRNA-based cancer vaccines for colorectal and pancreatic cancers.Experts say the positive melanoma results could give further momentum to research into personalised cancer vaccines and potentially expand the use of mRNA technology in cancer treatment.