November 10, 2006
The body's immune system can fight the deadly cancer melanoma if scientists can flip the system's â€œoffâ€ switch to â€œon,â€ two preliminary studies suggest.
Scientists have long sought to rev up the disease-fighting cells of the immune system to fight melanoma. The new work addresses the other side of the coin â€“ the regulatory cells that normally keep disease-fighting cells in check.
By shutting off those inhibiting cells, scientists hope to enable the disease-fighting cells to mount a continuous attack on the cancer. Two new studies of that strategy were reported this week in Prague, Czech Republic, at a European cancer research meeting.
â€œThis is a fundamentally different approach to treating cancer,â€ said Dr. Alexander Eggermont, professor of surgical oncology at the University of Rotterdam, Netherlands, the conference's chairman. Eggermont was not connected to either of the skin cancer research papers.
Advanced melanoma is a devastating disease for which there is no effective treatment. The average life expectancy is about nine months, and less than 20 percent of patients survive more than two years after diagnosis.
In one paper, Dr. Jason Chesney from the J.G. Brown Cancer Center in Louisville, Ky., reported that when patients with advanced melanoma were given a drug combination to knock out their T-regulatory cells, tumors shrank or remained stable in five of seven participants.
â€œThis is a landmark study,â€ said Dr. Anna Pavlick, director of the melanoma program at New York University Medical Center's cancer institute, who was not involved in the study. â€œWhat it shows is that by suppressing T-regulatory cells, we can take the brakes off a patient's immune system.â€
In another study presented Wednesday, Dr. Jeffrey Weber, a professor of medicine at the University of Southern California, described how he and colleagues were able to block a protein on the T-regulatory cells. That inhibited them enough for the immune system to attack cancer cells.
Out of 25 patients tested, 24 are alive after 17 months, and three are free of cancer.