|
 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 Thursday'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 dermatology researcher at the New York University Cancer Institute in New York 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.
And two years after his remarkable recovery, the patient fell out of contact with researchers and scientists do not know his current condition. The man, who lives in a small town in Oregon, has declined media interviews, Yee said.
Melanoma is a cancer in the skin cells that make pigments and cause skin to tan, as part of the body's attempt to protect itself from ultraviolet radiation in sunlight. Cancer begins when radiation overloads and damages the cells, causing mutations.
About 62,000 news cases are diagnosed in the United States each year, and there are about 8,000 melanoma deaths.
When caught early, melanomas can be easily treated by surgically removing the cancerous patch of skin. But "once it has spread, basically nothing works," Rigel said.
Recently, however, scientists began thinking they might have another option
-- helping the body's immune system.
Doctors had long thought that 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. Experiments have also involved giving patients chemotherapy or other drugs that are toxic to patients but can help the immune system's ability to fight cancer.
[to top of second column] |
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.
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.
The fourth patient they treated was the Oregon man, who had a melanoma on his back before it had spread to his groin and right lung. He was treated in July 2005. Two months after the treatment, advanced scans of his body revealed no tumors. Two years after the treatment, he had no symptoms.
More good news: There were no harmful side effects. What's more, an analysis showed that his immune system had targeted not only one type of protein target on cancer cells, but two others as well.
It's possible the treatment spurred his immune system to expand its cancer-fighting ability in new ways, Yee said.
However, 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.
___
On The Net:
New England Journal: http://nejm.org/
[Associated
Press; By MIKE STOBBE]
Copyright 2008 The Associated
Press. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
