Biopharmaceutical company GTx is commencing a Phase II open-label study of selective androgen receptor modulator enobosarm (GTx-024), to treat estrogen receptor (ER) positive metastatic breast cancer.
The proof-of-concept study is designed to randomise 20 postmenopausal women with ER-positive metastatic breast cancer, and who have previously responded to hormone therapy, at around six sites in the US.
Dana Farber Cancer Institute inflammatory breast cancer programme director, Harvard Medical School assistant professor of medicine and enobosarm Phase II study clinical investigator Dr Beth Overmoyer said androgen (male hormone) therapy can be effective for women who’s cancer has progressed after tamoxifen treatment, but side-effects such as deepening of the voice and facial hair growth make this option unacceptable to many.
"Hopefully, treatment with enobosarm will result in efficacy similar to androgen therapy without the masculinising side effects," Overmoyer said.
Until the women show clinical progression or have completed the 336-day treatment period, 9mg of enobosarm will given each day.
Clinical benefit, which will be assessed at six months, is the primary endpoint, and is defined as either those women receiving treatment who have demonstrated a complete response, a partial response or stable disease.
GTx chief executive officer Mitchell Steiner said; "Enobosarm would be the first new targeted hormonal therapy introduced for the treatment of breast cancer in many years."