GTx, Inc. announced that the United States Food and Drug Administration has accepted for filing and review the New Drug Application (NDA) for toremifene 80 mg, an oral selective estrogen receptor modulator, which GTx seeks to market for the prevention of bone fractures in men with prostate cancer on androgen deprivation therapy (ADT).

The NDA is supported by results from a two year, double blind, placebo controlled, randomized phase III clinical trial of 1,382 men with advanced prostate cancer on ADT.

GTx expects to hear within several weeks whether the NDA will receive priority or standard review.

ADT, primary treatment for advanced prostate cancer, has improved survival in men with prostate cancer. Approximately 700,000 men with prostate cancer are being treated with ADT and an estimated 100,000 are anticipated to initiate ADT each year.

ADT works by reducing testosterone to castrate levels. Testosterone, through the process of aromatization, is converted to estrogen. Healthy elderly men actually have higher levels of estrogen than do postmenopausal women. Because ADT reduces testosterone levels by up to 95%, it also substantially depletes estrogen levels.

Although estrogen is commonly thought of as a female sex hormone, it plays a critical role in men's health. Estradiol is the primary hormone responsible for bone turnover and bone quality. It is also important for cognition and the regulation of certain central nervous system functions and metabolism. Depletion of estrogen can result in serious side effects of ADT, including a high risk of bone fractures, adverse lipid changes and increased risk of cardiovascular disease, as well as common symptomatic side effects such as growth of breast tissue often accompanied by tenderness and pain, and hot flashes.

Of patients on ADT, up to 77 percent develop significant bone loss, making them susceptible to fracture. Recent studies indicate that the annual risk of fracture in men on ADT is 5% to 8%, or three times higher than the risk of fracture for postmenopausal women. Fractures are serious and can reduce survival in men on ADT by more than three years.

GTx, Inc., headquartered in Memphis, Tennessee, is a biopharmaceutical company dedicated to the discovery, development, and commercialization of small molecules that selectively target hormone pathways to treat cancer, osteoporosis and bone loss, muscle loss and other serious medical conditions.