Combination Radiation/Vaccine Therapy for Prostate Cancer May Benefit Some Patients from National Institutes of Health News, US Dept of Health and Human Services.

A pilot study of an experimental therapy for prostate cancer has found that a cancer vaccine can be safely administered to patients undergoing radiation therapy. In some patients receiving the vaccine, an immune response against tumor cells may occur, according to the results of a phase II clinical trial led by scientists at the National Cancer Institute (NCI), part of the National Institutes of Health. A strong immune response is an indication that the body is fighting the cancer.
This was the first trial to combine radiation and a cancer vaccine for treating prostate cancer, and the results now pave the way for a larger trial to evaluate the efficacy of the combination therapy in treating the disease. The combination therapy was well tolerated.

Cancer vaccines are intended either to treat existing cancers or to prevent the development of cancer. The experimental vaccine used in this study was designed to strengthen the body’s natural defenses against prostate cancer.

“The idea is that you can stimulate the body’s immune system to recognize and attack tumor cells through the use of a vaccine,” explained James L. Gulley, M.D., Ph.D., of NCI’s Laboratory of Tumor Immunology and Biology and the first author on the study. The study appears in the May 2005 issue of Clinical Cancer Research

Thirteen of 17 patients who received the combination therapy had at least a three-fold increase in immune cells that attack a protein on the surface of tumor cells, compared to no detectable increases in eight patients who received radiation alone. The researchers also found evidence that the vaccine may have “revved up” the immune systems of some patients against other tumor proteins.

The rationale for testing a vaccine/radiation combination came from the preclinical observations that radiation can alter tumor cells in a way that makes it easier for the body’s immune system to kill tumors. Furthermore, mice were cured of tumors when give