Canadian urology firm Sophiris Bio has dosed the first patient in a Phase III trial of PRX302 (topsalysin) for the treatment for lower urinary tract symptoms of benign prostatic hyperplasia (BPH or enlarged prostate).
A total of 440 patients will be enrolled in the randomised, double-blind, vehicle-controlled, dose confirmation, multicentre Phase III trial, called the PLUS-1 study.
The trial is aimed at evaluating the safety and efficacy of a single intraprostatic injection of PRX302 (0.6 µg/g prostate) for the treatment of BPH.
Primary endpoint of the trial is the International Prostate Symptom Score (IPSS) total score change from baseline over 52 weeks, while the secondary endpoints include Qmax change from baseline (maximum urine flow) over 52 weeks.
Sophiris's lead candidate for BPH, PRX302, is designed to be as efficacious as pharmaceuticals, less invasive than the surgical interventions, and without the sexual side effects seen with existing treatments.
PRX302 is based on company's PORxin technology platform and is administered through intraprostatic, transperineal and transrectal injection.
It is precisely targeted to the prostate tissue constricting the urethra without damaging neighbouring healthy tissue.
According to the results from the randomised, double-blind, vehicle-controlled Phase IIb trial, PRX302 showed improvement in both subjective and objective measures of BPH symptoms.
In the trial, 126 patients with BPH were treated with PRX302 and no drug-related erectile dysfunction or cardiovascular side-effects have been reported.
PRX302 is designed to be a once-a-year treatment for the long-term relief of BPH symptoms without causing sexual dysfunction or sacrificing quality of life.
The drug candidate is a targeted prodrug consisting of a recombinant modified form of the Aeromonas protoxin proaerolysin, bearing a prostate-specific protease cleavage site, with potential antineoplastic activity.
Benign prostatic hyperplasia (BPH) is an enlarged prostate gland that often results in a constricted or partially blocked urethra which would lead to frequent and difficult urination, discomfort, and other complications with urinating.
Over five million men are estimated to be suffering from the symptoms of BPH in the US alone.
The company said existing once-daily oral drugs for BPH, often lack sustainable efficacy and may be associated with undesirable side effects including sexual dysfunction.
Image: Micrograph of nodular hyperplasia of the prostate, also known as benign prostatic hyperplasia (BPH) and benign prostatic hypertrophy. Photo: courtesy of Nephron.