A personalised cancer vaccine has shown encouraging results in a major trial involving more than 1,000 patients with high-risk melanoma. Developed by Moderna and Merck, the Intismeran vaccine is given after surgery alongside Keytruda, an immunotherapy drug already used to treat cancer. Early results suggest the combination significantly extends the period patients remain cancer-free and reduces the risk of melanoma spreading to other organs compared with Keytruda alone. The vaccine uses mRNA technology to create treatment specifically tailored to each patient’s tumour. Scientists analyse genetic mutations from a removed tumour sample and produce a vaccine that trains the immune system to recognise and attack remaining cancer cells. Researchers are also testing similar personalised vaccines against lung, bladder and kidney cancers. Cancer specialists have described the findings as potentially significant evidence that personalised cancer vaccines can work, while cautioning that full trial results still require independent review. Regulatory approval would also be needed before the treatment could become routinely available to patients.