London ? The body’s own immune system can fight the deadly cancer melanoma if scientists can flip the system’s “off” switch to “on,” 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: the regulatory cells that normally keep disease-fighting cells in check.

By shutting those inhibiting cells off, 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 at a cancer meeting.

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.

In another study, Dr. Jeffrey Weber, a professor of medicine at the University of Southern California in Los Angeles, 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.