Watson Pharmaceuticals' TRELSTAR receives FDA approval for treatment of advanced prostate cancer

Watson Pharmaceuticals, Inc. (NYSE: WPI), today announced the U.S. Food and Drug Administration (FDA) approval of TRELSTAR® 22.5 mg (triptorelin pamoate for injectable suspension), a new twice-yearly formulation of TRELSTAR®, a proven, simple and effective palliative treatment of advanced prostate cancer. With an anticipated May launch, TRELSTAR® 22.5 mg is the first and only six-month intramuscular (IM) GnRH agonist available for the palliative treatment of advanced prostate cancer. TRELSTAR® 22.5 mg is also the only six-month GnRH agonist that is stored at room temperature; no refrigeration is required.  

TRELSTAR® 22.5 mg releases triptorelin pamoate, a gonadotropin releasing hormone (GnRH) agonist, over a prolonged period and, in turn, suppresses testosterone production for six months. Developed by Debiopharm Group and first approved in the U.S. in 2000, TRELSTAR® is indicated for the palliative treatment of advanced prostate cancer and is currently available in one-month (3.75 mg) and three-month (11.25 mg) forms.  The new, longer-acting six-month formulation is designed to provide patients and physicians with a more convenient therapeutic option that is well tolerated and as effective.

TRELSTAR® is administered via the MIXJECT® delivery system, which utilizes a thin (21-gauge) needle, and thereby offers easy administration with low incidence of injection site pain.  In fact, in the clinical trial, only 1.7% of patients reported injection site pain.  Following administration, the MIXJECT® needle is captured to help comply with OSHA regulations.

"TRELSTAR® 22.5 mg builds on our extensive and established urology portfolio, and the forthcoming May launch will mark another critical milestone in the growth of our Brand business," said Fred Wilkinson, Executive Vice President, Global Brands at Watson.  "We are confident that the unique combination of convenience, reliable testosterone and PSA suppression, and injection site tolerability of this longer-acting TRELSTAR® formulation will provide advanced prostate cancer patients and their physicians an important treatment option.  In fact, we plan to further evaluate and quantify the unique injection site tolerability this product offers as compared to other commonly used GnRH agonists later this year."

The approval is based on a 12-month (48 week) phase 3 study evaluating the efficacy, pharmacokinetics, and safety of TRELSTAR® 22.5 mg administered every six months (24 weeks) in patients with advanced prostate cancer.  Over the study, TRELSTAR® 22.5 mg produced a mean testosterone serum level of 12.8 ng/dL from month two through month 12, well below castration levels associated with androgen deprivation therapy.  By day 29, 97.5% of the clinical trial patients achieved castrate level, and >98% of all patients were below castrate level at month six and month 12.  Median prostate specific antigen (PSA) was also reduced by 96.4% at the end of the study. The most commonly reported adverse events associated with the use of TRELSTAR® 22.5 mg included hot flushes (71.7%), erectile dysfunction (10.0%), and testicular atrophy (7.5%).

SOURCE Watson Pharmaceuticals, Inc.