Researchers at the University of Pennsylvania have described a treatment that may signify a turning point in the long struggle to develop effective gene therapies against cancer.

It uses a disabled form of HIV-1, the virus that causes AIDS, to carry cancer-fighting genes into the patients’ T-cells. The team is using gene therapy to accomplish something that researchers have hoped to do for decades: train a person’s own immune system to kill cancer cells.

To make T-cells search out and destroy cancer, researchers have equipped them to do several tasks: recognize the cancer, attack it, multiply, and live on inside the patient. In some patients, the T-cells modified by the researchers multiplied to 1,000 to 10,000 times the number infused, wiped out the cancer, and then gradually diminished, leaving a population of “memory” cells that can quickly proliferate again if needed.

Ref.: David L. Porter, M.D., Bruce L. Levine, Ph.D., Michael Kalos, Ph.D., Adam Bagg, M.D., and Carl H. June, M.D., Chimeric Antigen Receptor-Modified T Cells in Chronic Lymphoid Leukemia, New England Journal of Medicine, August 2011