MEMPHIS, Tenn. — GTx, Inc. announced today that it is initiating a proof of concept, Phase 2, open-label clinical study to evaluate enobosarm (GTx-024), a selective androgen receptor modulator (SARM), for the potential treatment of metastatic breast cancer.
"We know from prior studies that women with hormone receptor positive metastatic breast cancer which has progressed following treatment with tamoxifen often respond to androgen (male hormone) therapy; yet the side effects, such as facial hair growth and deepening of the voice, are not acceptable to most patients," said Beth A. Overmoyer, M.D., a clinical investigator in this enobosarm Phase 2 study and the Director, Inflammatory Breast Cancer Program, Dana Farber Cancer Institute and Assistant Professor of Medicine at the Harvard Medical School. "Hopefully, treatment with enobosarm will result in efficacy similar to androgen therapy without the masculinizing side effects."
"We believe enobosarm has the potential to selectively treat metastatic breast cancer while minimizing the unwanted side effects associated with steroidal androgens," said Mitchell S. Steiner, MD, Chief Executive Officer of GTx. "Enobosarm would be the first new targeted hormonal therapy introduced for the treatment of breast cancer in many years."
The proof of concept, Phase 2, open-label study will randomize twenty (20) postmenopausal women with estrogen receptor (ER) positive metastatic breast cancer who have previously responded to hormone therapy at approximately six clinical sites in the United States. The women will receive 9 mg of enobosarm once a day until they evidence clinical progression or have completed 336 days of treatment. The primary endpoint is clinical benefit, which will be assessed at 6 months, and is defined as either those women receiving treatment who have demonstrated a complete response (disappearance of all targeted lesions), a partial response (at least a 30% decrease in the sum of the diameters of the targeted lesions) or stable disease (no disease progression from baseline). The response from treatment will be correlated with androgen receptor (AR) status of tumor samples from the women. The study will recruit women 18 or older with ER positive metastatic breast cancer who have previously responded to adjuvant hormonal therapy for 3 years or longer and women diagnosed with metastatic disease who have been treated with hormonal therapy for at least 6 months and now have progressive disease.