Raloxifene May Slow Progression of Androgen Independent Prostate Cancer

March 21, 2006. In a small study to be published in the April, 2006 issue of the British Journal of Urology International, researchers at Cedars-Sinai Medical Center have shown that Raloxifene, a drug commonly used to treat osteoporosis, has a potential clinical benefit in treating men with prostate cancer. This study has implications for the approximately 35,000 men who will die this year of advanced prostate cancer in the United States alone.

Prostate cancer is the leading cause of cancer and the second leading cause of cancer-related death among men living in the US. Approximately one in six men will be diagnosed with prostate cancer during his lifetime.

“We undertook this study because we desperately need new therapies for patients with advanced prostate cancer,” said David B. Agus, M.D., research director of the Louis Warschaw Prostate Cancer Center at Cedars-Sinai and principal investigator of the study.

Twenty-one patients with Androgen Independent Prostate Cancer (AIPC) and evidence of disease progression were enrolled into the clinical trial and given daily oral raloxifene.

Eighteen patients remained on study throughout and were counted in the evaluation of the drug's efficacy. Three withdrew before the first evaluation. At the first evaluation, five men had stable disease and continued on the study for a median of five cycles. The longest response was 17 cycles. Drug related toxicity was minimal.

Since Raloxifene is a drug already on the market, researchers were able to run this Phase II clinical trial without Phase I tests for toxicity. They identified the presence of the beta isoform of the estrogen receptor in prostate cancer tissue samples, then moved directly into studies of animals with human prostate cancer, and then onto human clinical trials. The entire process took only 2-3 years.

“It used to be that to show effectiveness through research studies, cancer drugs needed to shrink tumors by 50 percent,” Agus said. “Now, the new way of thinking about the effectiveness of cancer drugs is whether they can slow cancer’s growth, which ultimately may significantly benefit patients.”

Through the study, patients were given a daily oral dosage of Raloxifene, and the disease and its symptoms were followed on a regular basis. Some of the patients in the clinical trial taking Raloxifene showed evidence of disease stabilization manifested by a slowing or stopping of the growth of their prostate cancer.

According to Ronald L. Shazer, M.D., primary author of the manuscript, “The outcome from the Phase II clinical trial merits further study in a randomized clinical trial to demonstrate the clinical benefit of this targeted therapy.”

This article posted March 21, 2006 by J. Strax.