Melanoma treatment uses immune system to kill cancer cells

A combination of two immunotherapy drugs used against highly advanced melanoma — the deadliest form of skin cancer — caused tumors to dramatically shrink or disappear, according to a study released Wednesday. The results of the research from the Memorial Sloan Kettering Cancer Center in New York are part of a transformative advance in harnessing the body's immune system to kill cancer cells.

In the new study, some 40 percent of patients in the study saw reduction in their huge tumors from the treatment, which combines a drug called ipilimumab and an experimental new immunotherapy known as Nivolumab. They're part of a treatment trend that uses the immune system to help reject cancer.

,Immunotherapies are being found effective against lung, kidney and many other cancers, as well.

Immunotherapy has been a dream of cancer researchers for more than a century. But the field has been marked by a few tantalizing successes, followed by years of failure. Researchers believe they now understand the immune system well to start employing it reliably against cancer.

The treatment starts with the understanding that a type of immune system cells — white blood cells called killer T-cells — try to destroy cancer cells. But cancer cells are tricky and they release an array of chemicals to keep the killer T-cells at bay. To completely destroy the cancer cell, the killer T-cell usually has to connect to it in two places.

The next step was to aim the killer T-cells at the second site. Several experimental drugs have been developed for that.  

Also, the drugs have side effects — often nothing more than a bad rash, but they also can cause inflammation of the intestine or the liver. And they are expensive. 

Despite those limitations, immunotherapy is an exciting new concept. Experts say it stands a very good chance of curing many patients whose cancer would have been fatal.