A man who had been given less than a year to live had a complete remission of advanced deadly skin cancer after an experimental treatment that revved up his immune system to fight the tumors. The 52-year-old patient's dramatic turnaround was the only success in a small study, leading doctors to be cautious in their enthusiasm. However, the treatment reported in ... The New England Journal of Medicine is being counted as the latest in a small series of successes involving immune-priming treatments against deadly skin cancers. Immunotherapy has become the most promising approach" to late-stage, death-sentence skin cancers, said Dr. Darrell Rigel, a dermatology researcher at the New York University Cancer Institute in New York. About 20 years ago, some scientists discovered that immune cells could latch onto and attack skin cancers. "There's a long history behind all of this," said Dr. Steven Rosenberg of the National Cancer Institute. In recent experiments, Rosenberg and other researchers have focused on souping up a certain kind of immune system cell - the "killer T cells" that envelop and kill foreign agents. Scientists focused ... on specific helper T cells that are adept at locking onto a cancer cell and guiding the killer cells to their target. The researchers drew blood from patients, located the special helper cells and then grew more of them in the laboratory. They then infused roughly 5 billion of the cells back into the patients without chemotherapy or the other harsh drugs. "It's a simpler and less toxic approach to melanoma than had been previously employed," said Dr. Louis Weiner, director of the cancer center at Georgetown University.