Merck and Moderna reported positive top-line results from a Phase 3 trial of an investigational mRNA-based treatment for people with completely removed, high-risk melanoma.The treatment, called intismeran autogene, is designed using the unique mutation pattern in a patient's tumor. It is given with the immunotherapy pembrolizumab, also known as KEYTRUDA.In the trial, the combination met its main goal of improving recurrence-free survival and also met a key goal related to keeping cancer from spreading to distant parts of the body, compared with KEYTRUDA alone.The study enrolled 1,137 people and will continue to look at other outcomes, including overall survival. The companies said they plan to present the full data at a medical meeting and discuss possible filings with regulators.The treatment is still being studied and is not being presented as an approved vaccine. The result is an early sign that cancer care tailored to one person's tumor may become a useful part of future treatment.