Using the Body's Immune System to Fight Cancer

Richard Edelson, MD

In 1982, Dr. Richard Edelson and his team were looking for a treatment for cutaneous T-cell lymphoma (CTCL), a cancer caused by the uncontrolled growth of white blood cells known as T-cells. The life expectancy of the advanced leukemic stage of CTCL was just 18 months and there was little he could do to relieve the extremely inflamed and painful skin associated with it. He knew that a powerful drug activated by light was used to stop the spread of psoriasis, so he decided to try using it to decrease the number of cancer cells in the blood, hoping to diminish the symptoms and perhaps prolong patient survival. He devised a method of bringing the blood outside the body, where it was mixed with the drug and exposed to light before being returned to the patient. He started with one patient who had not responded to high-dose chemotherapy and, in order to determine whether the procedure was safe, he initially treated the patient only two days in a row at monthly intervals for three months. It was not expected that the initial step of treating only 5 percent of the patient's malignant cells would produce any clinical results, and Dr. Edelson thought he would have to accelerate to treatments every day. But after just the third treatment, the extraordinary results surprised everyone: the patient was in complete remission! His skin was clear and there were no malignant cells detected in his blood. A larger clinical trial with 39 patients showed that one-quarter of them had a similar response, and in 1988 the Food and Drug Administration fast-track approved the treatment, known as photopheresis, for the treatment of CTCL.

Since then, photopheresis has been used around the world about 400,000 times to treat more than 20,000 patients. Today, it's used not just for CTCL, but also to treat graft-versus-host-disease (a side effect of bone marrow transplants) and to prevent rejection following heart transplants. Meanwhile, Dr. Edelson and his team have spent the last 20 years improving photopheresis and studying the mechanism by which it works. Since that first patient, they have learned that this procedure stimulates blood cells known as monocytes to transform into cells that act as an ignition to turn on the immune system. By exposing these cells to a patient's cancer cells, a kind of personalized vaccine is created in which the new cells are able to seek out and destroy cancer cells in the body. They hope to soon bring the new knowledge they acquired in the laboratory into clinical trials for other types of cancer. The support of patients willing to participate in research studies has brought an exciting new treatment to thousands of individuals and has the potential to bring it to many more.