"As part of this research grant we have had encouraging results involving two smaller clinical studies", stated Svend Freytag, Ph.D., division head of Research, Radiation Oncology, Henry Ford Hospital. Dr. Freytag, along with Benjamin Movsas, M.D., chair of Radiation Oncology and Hans Stricker, M.D., vice chair of Urology at Henry Ford Hospital are the study's key researchers.
Because of the results from the previous trials, NCI approved a phase III trial involving 280 prostate cancer patients over a three-year period. A phase III trial is the final stage in a study to determine if the treatment being studied should become the standard treatment.
Currently radiation therapy - without the gene therapy - or surgical removal of the prostate is the standard treatment for patients with localized prostate cancer, with similar cure rates. Prostate cancer is the second leading cause of cancer death for men according to the American Cancer Society.
"When you consider that across the world most trials involving gene therapy are in very early stages of development involving research in test tubes, the fact that Henry Ford Hospital is now embarking on a major phase III clinical trial to test this as a new standard treatment, is a testament to the world class innovative research taking place right here", stated Dr. Movsas, principal investigator of the study. "To my knowledge, this is the only place in the world where such a gene therapy study is available for this group of patients", he added.
The first FDA-approved clinical trial studied approximately 15 men who previously had radiation therapy alone and experienced cancer regrowth. They were given only the suicide gene therapy, which was proven safe. Suicide gene therapy uses two specific genes, encased in a virus - the one associated with the common cold, to convert non-toxic drugs into highly toxic agents when the genes are inserted into a tumour. The genes activate chemotherapeutic agents locally to destroy the cancer cells and make them more sensitive to enhance the effectiveness of radiation therapy.
In this setting gene therapy didn't eliminate the cancer, but it did slow its rate of growth and delayed by an average of 2,5 years, when the patients began hormone therapy. Since hormone therapy can be associated with many side effects, delaying the therapy can improve a patient's quality of life.
The second trial of about 25 men with newly diagnosed prostate cancer combined the suicide gene therapy with radiation therapy. Again, it proved safe and demonstrated a benefit in a certain class of patients. Researchers found that all of the patients with intermediate-risk prostate cancer - the group eligible for this study - had excellent responses following the combined treatment, with no evidence of cancer regrowth to date.
The main criteria for the phase III study requires either a patient's PSA to be in the range of 10-20 and/or a Gleason score of 7 - moderately differentiated tumour cells on the prostate biopsy.
In this randomized study, half of the patients will receive the standard treatment for intermediate prostate cancer involving Intensity Modulated Radiation Therapy (IMRT), a high-precision radiation therapy technique using computer-controlled x-ray beams so that the radiation delivery conforms to the shape of the tumour. The other half will receive the combination treatment involving the gene therapy with IMRT to see which treatment is most effective.