“The patient group that took the potential vaccine and Keytruda saw a 44% reduction in the risk of death or the cancer returning, the companies said.

The treatments continued for about a year in both groups unless the disease came back or side effects became too severe.
Merck and Moderna expect to start a phase 3 study next year, and the companies say they intend to expand their approach to other tumor types.”

https://www.nbcnews.com/health/health-news/moderna-says-personalized-mrna-cancer-vaccine-effective-advanced-melan-rcna61526