GTx disappointed by drug for prevention of prostate cancer

MEMPHIS, Tenn.– Cancer Digest – GTx, Inc. today announced disappointing initial results of
a key clinical trial evaluating the effectiveness of its drug, toremifene, to prevent prostate cancer in men at high risk for the disease.	Prostate cancer is a hormonally driven disease, and both testosterone and estrogen are required for its development and progression. GTx believes that by selectively blocking estrogen receptors needed for prostate cell proliferation, toremifene 20 mg may be an ideal anti-estrogen for prevention of prostate cancer. (Image courtesy of GTx, Inc.)

The results were for a trial of nearly 1,600 men high grade prostatic intraepithelial neoplasia, or PIN, treated with 20mg doses of toremifene, which modifies an estrogen receptor that cancer uses to stimulate growth. PIN is a premalignant mass growing within the prostate.


“We designed the Phase III trial based upon the successful outcome of our Phase IIb clinical trial,” said Dr. Mitchell S. Steiner, CEO of GTx. “Toremifene 20 mg did also reduce prostate cancer in our Phase III study but based on our review of the topline data, there is not a sufficient reduction in cancers compared to placebo over a three year period to demonstrate the statistical significance required for this study. We intend to review all data from the study this summer to better understand the trial results and the ability of toremifene 20 mg to reduce cancer among these high-risk men.”

In the study 1,590 men with high grade PIN were randomly assigned to treatment with toremifene or placebo in a three-year clinical trial. The objective was to see if the drug reduced the incidence of prostate cancer among the men treated with at least one dose of the study drug and had undergone at least one on-study prostate biopsy.

In the initial analysis of the data, 45.5 percent of the men in the placebo group did develop prostate cancer within three years compared to 35.3 percent of the men in the toremifene group, but 10.2 percent reduction compared to the placebo group was not considered statistically significant.
In the study, there were no clinically significant differences in the adverse side effects experienced by men treated with toremifene and men receiving placebo.

GTx has submitted to FDA a protocol for the second toremifene study using an 80 mg dose trial and will meet with FDA this summer to finalize the trial design.

GTx has secured funding for this clinical study through the expansion of its partnership with Ipsen which was announced March 23, 2010. GTx expects to initiate the TREAT 2 (Toremifene for Reduction of fractures and other Estrogen deficiency side effects in men on Androgen deprivation Therapy) Phase III clinical trial by the end of 2010.

SOURCE: adapted from press materials provided by GTx, Inc.