Watson Pharmaceuticals will attempt to differentiate its Phase III benign prostatic hyperplasia candidate silodosin over existing treatments by emphasizing the compound's rapid onset of action and tolerability profile, the company told "The Pink Sheet" DAILY.

On Jan. 16, Watson released top-line data from two Phase III trials showing that silodosin achieved its primary and secondary endpoints. The trials' primary endpoint was to show that 8 mg of silodosin once a day for 12 weeks was superior to placebo based on the change in the International Prostate Symptom Score-1. The secondary endpoint was improvement in maximum urine flow.

As a result of the positive data, the firm said it is on track to submit an NDA for the alpha (1A)-adrenoceptor agonist in the first half of 2008. Watson told "The Pink Sheet" DAILY that it anticipates a possible launch in 2009.

If approved, silodosin would directly compete with GlaxoSmithKline's Avodart (dutasteride), Pfizer's Cardura XL (doxazosin extended-release) and Merck's Proscar (finasteride). According to Watson, approximately $1.7 billion is spent annually on BPH drugs.

Watson received the rights for silodosin in the U.S., Canada and Mexico under a 2004 agreement with Japan's Kissei Pharmaceuticals. Sildosin launched in Japan in May 2006 under the name Urief and is comarketed there with Daiichi Pharmaceutical.

Although silodosin would be Watson's first BPH branded product, the firm also markets Oxytrol (oxybutynin transdermal system) for overactive bladder. In addition, the firm anticipates completing a Phase III trial of an oxybutynin gel in the first or second quarter and is also pursuing a line extension of its prostate cancer treatment Trelstar (triptorelin injection) into advanced prostate cancer with partner Debiopharm.

- Jonathan M. Block (j.block@elsevier.com)

Phase III Results Buoy Watson’s Benign Prostatic Hyperplasia Candidate

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