A clinical trial shows a vaccine combined with the immune-boosting drug Interleukin-2 can improve outcomes for advanced melanoma, U.S. researchers say. The study, published in the New England Journal of Medicine, says therapeutic cancer vaccines unlike vaccines that prevent infection, are intended to jump-start the immune system to help it battle existing tumors. \"This is the first time that a vaccine has shown benefit in the treatment of patients with metastatic melanoma. The trial is an early example of success with a cancer vaccine,\" Dr. Howard Kaufman, a study co-investigator who is director for the Rush University Cancer Center, says in a statement. \"If we can use the body\'s own defense system to attack tumor cells, we provide a mechanism for ridding the body of cancer without destroying healthy tissue.\" The researchers randomly assigned 185 patients with metastatic melanoma the most serious type of melanoma to either a combination of the peptide vaccine, which is a small portion of protein that is present on the surface of the melanoma cancer cells, and Interleukin-2, a drug that activates the immune system, or a high dose of Interleukin-2 alone. The study, published in the New England Journal of Medicine, found about 16 percent of study participants given the vaccine and Interleukin-2 combination saw tumors shrink by 50 percent or more, compared with 6 percent given Interleukin-2 alone.