GTx, Inc announced the submission of a New Drug Application with the US Food and Drug Administration (FDA) for toremifene 80 mg, an oral selective estrogen receptor modulator (SERM), for the prevention of bone fractures in men with prostate cancer on androgen deprivation therapy (ADT).

"ADT has helped improve survival for men with advanced prostate cancer. Unfortunately, ADT may cause unintended serious estrogen deficiency side effects, such as a high risk of fractures, which can shorten survival," said Dr Mitchell Steiner, CEO of GTx. "If approved, toremifene 80 mg could become the first cancer care agent for the prevention of fractures in men receiving ADT."

Ipsen Group has licensed European toremifene rights from GTx and is planning to submit a marketing application in 2009 in its licensed territories for the use of toremifene 80 mg for this indication.

The submission 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. The clinical trial, the first ever fracture prevention study in men on ADT, was conducted under a special protocol assessment with FDA. Toremifene 80 mg met the primary endpoint of the clinical trial, a reduction in new morphometric vertebral fractures compared to placebo, as well as other key secondary endpoints related to estrogen deficiency side effects of ADT. Because there are no FDA approved treatments for this indication, GTx has requested priority review for toremifene 80 mg.

Additionally, in the phase-III clinical trial, toremifene 80 mg was generally well tolerated. Among the most common adverse events that occurred in over 2 per cent of study subjects in the toremifene and placebo groups were joint pain, dizziness, back pain, and extremity pain.

Toremifene has been marketed for the treatment of advanced breast cancer in more than 60 countries including the US. "The phase-III ADT clinical trial safety data are consistent with the existing 17 year pharmacovigilance database which includes approximately 480,000 patient years use of toremifene citrate," said Ronald A Morton chief medical officer of GTx.

ADT is the primary treatment for advanced prostate cancer in the U.S. Approximately 700,000 men with prostate cancer are being treated with ADT and an estimated 100,000 are anticipated to initiate ADT each year.

GTx 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 wasting and other serious medical conditions.