Sophiris Bio Inc. announced that enrollment has begun and the first patients have been dosed in a Phase 3 trial of PRX302 (topsalysin) as a treatment for lower urinary tract symptoms of benign prostatic hyperplasia. The Phase 3 international, multi-center study, called the PLUS-1 study, will enroll approximately 440 patients. The randomized, double-blind and vehicle-controlled study will assess the safety and efficacy of a single intraprostatic injection of PRX302 (0.6 µg/g prostate) for the treatment of BPH.

The primary endpoint is the International Prostate Symptom Score (IPSS) total score change from baseline over 52 weeks. Secondary endpoints include Qmax change from baseline over 52 weeks. PRX302 is highly targeted to prostate tissue and is delivered directly to the prostate via a localized injection.

PRX302 is designed to be at least as efficacious as oral pharmaceuticals while being less invasive than surgical interventions, and without the sexual side effects that may be seen with existing treatments. In a previously completed randomized, double-blind, vehicle-controlled Phase 2b trial, PRX302 produced sustained clinically meaningful and significant improvement in both subjective and objective measures of BPH symptoms. In total, 126 patients with BPH have been treated with PRX302 and no drug-related erectile dysfunction or cardiovascular side effects have been reported. BPH is an enlarged prostate gland often resulting in a constricted or partially blocked urethra that can lead to frequent and difficult urination, discomfort, and other complications with urinating.

It is estimated that more than 5 million men in the United States alone are bothered by symptoms of BPH. Current oral drugs for BPH, which are taken daily, often lack sustainable efficacy and may be associated with undesirable side effects including sexual dysfunction. More aggressive treatment options include invasive surgical procedures, which may also cause sexual dysfunction.