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 yesterday's issue of 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 clinical professor of dermatology at the New York University Medical Center in Manhattan who had no role in the research.
Still, the immune-priming experiments have yet to yield a consistent therapy. Even researchers who worked on the experiment involving nine patients and just one success are quick to couch the result. "This is only one patient," said study co-author Dr. Cassian Yee of the Fred Hutchinson Cancer Research Center in Seattle.
Researchers used a single infection-fighting cell from the man's immune system, CD4 T cell, copies of which were grown in a laboratory. The disease had spread to the man's lungs and a lymph node before he received the two-hour infusion of lab-grown immune system cells. Sixty days later, all signs of the disease were gone. He remained in remission for the following two years at which point he requested not to be contacted further by researchers or the media, a spokesman for the research center said.
Doctors had long thought immune system cells, which so effectively attack foreign threats like viruses, were giving a pass to cancer cells. The theory was that because cancers cells are generated by the body, the immune system perceived them as part of the body.
But 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, a pioneer in that research.
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.
The new research took a different approach. The Hutchinson center scientists focused instead on specific helper T cells that are adept at locking onto a cancer cell and guiding the killer cells to their target. It's possible the treatment spurred his immune system to expand its cancer-fighting ability in new ways, Yee said. But the case raised many unanswered questions. The man had been treated earlier with other drugs. It's possible those treatments had already weakened or altered the cancer.
Also, none of the eight other patients in the study did as well. It's not clear why.
Professor Karol Sikora, a cancer expert at London's Imperial College, said of the research, "I think we will be able to harness the power of the immune system. Patients will live with their cancer, and die with their cancer, but not of their cancer; it will be like diabetes today."
Facts about melanoma
The most common and deadly form of skin cancer, it begins in the melanocytes, the cells found in the epidermis, the top layer of the skin. They make the brown pigment called melanin, which makes skin tan and protects deeper layers of the skin from the sun's harmful effects. Cancer begins when radiation overloads and damages the cells, causing mutations.
Because most of these cells still make melanin, melanoma tumors are often brown or black though they can also have no color. Melanoma most often appears on the trunk of fair-skinned men and on the lower legs of fair-skinned women, but it can appear other places, too. Having dark skin lowers the risk, but a person with dark skin can still develop melanoma.
Almost always curable in its early stages but likely to spread to other parts of the body if untreated.
More than 62,000 people in the United States will be diagnosed with melanoma in 2008. Almost 8,500 patients will die from it.
SOURCE: AMERICAN CANCER SOCIETY
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