Helping the body kick out cancer.

Helping the body kick out cancer

With cancer, it's not that the body doesn't try to get rid of tumor cells, it's just that the effort fails. Steven A. Rosenberg and his colleagues at the National Cancer Institute have been investigating ways to boost the body's efforts; one such method has already had success in preliminary trials in humans (SN:12/7/85,p.359). But because the initial approach has some potentially serious side effects, Rosenberg and his colleagues are working on ways around the problem. In the Sept. 19 SCIENCE they report preliminary success in animal trials of one such method.

In their previous work, the researchers isolated a specific type of lymphocyte, or white blood cell, from the blood and incubated it with an immune system stimulator. They injected the resulting cells, called LAK (lymphokine-activated killer) cells, along with a booster of interleukin-2, into patients in whom all conventional therapy has failed. Of the first 55 patients treated, 21 showed a response and five of them have had a complete remission.

But the interleukin-2, while necessary for the process, also causes substantial side effects, primarily organ-damaging water retention. So Rosenberg is trying a more "dedicated" white blood cell, one that has already infiltrated the tumor.

In the mouse experiment, he and his colleagues collected white blood cells not from the blood but directly from tumors. In a series of experiments they found that the progeny of these cells, called tumor-infiltrating lymphocytes (TIL), had a dramatic effect on tumors.

When they combined TIL with only 10 to 20 percent of the interleukin-2 needed with LAK cells and an immune system suppressor to fight off the body's attempt to get rid of the foreign cells, the researchers say they were able to "cure" mice with induced cancer. In one experiment on 12 mice, they were able to clear up metastases in all the animals. The TIL cells, they found, are 50 to 100 times more potent than the LAK cells.

The researchers have been able to isolate the same class of white blood cells from human tumors. While they are currently awaiting U.S. Food and Drug Administration approval to try the procedure on humans, Rosenberg cautions that it is too early to tell whether the procedure will be successful. "A lot of things work in mice but don't work in people," he says. "I don't know if this will work."