Sophiris Bio, a urology company based in La Jolla, Calif., released data from its transrectal safety study, in which PRX302, the company's drug candidate for the treatment of benign prostatic hyperplasia (BPH or enlarged prostate), was well tolerated through three months following a transrectal injection.

The results support the use of a transrectal ultrasound (TRUS) guided injection for the delivery of PRX302 directly into the prostate. This route of administration will be used in future clinical trials of PRX302 in patients with BPH.

The primary objective of this small study was to evaluate the safety and tolerability of delivering PRX302 via a transrectal route of administration using TRUS. The data allow an assessment as to whether the safety profile from the transrectal delivery was similar to that observed with the transperineal route of administration, which had been used in all previous clinical studies with PRX302.

"The decision to move to a transrectal route of delivering PRX302 directly into the prostate as opposed to transperineal was made based on the input of our advisors and leading urologists treating patients with BPH," said Randall Woods, CEO of Sophiris Bio. "The transrectal route enables PRX302 to be administered by a urologist in an office based setting, in a brief procedure that does not require catheterization. To date 126 patients with BPH have been treated with PRX302 with a similar safety and tolerability profile between the transrectal and transperineal routes of administration."

This ongoing randomized, placebo controlled, double-blind, multicenter, phase I/II study enrolled 40 patients with moderate to severe BPH. Patients were randomized within one of four ascending dose cohorts, and the decision to move to the next higher dose was guided by an independent data monitoring committee that reviewed the safety data through day 15.

The primary endpoint of the study was to evaluate the three-month safety and tolerability of escalating doses of PRX302, although patients are to continue to be evaluated through month 12. The data from all four cohorts through month three indicate that PRX302 continues to be well tolerated with an adverse event profile similar to that seen in previous clinical studies using a transperineal injection. No drug-related sexual function adverse events were observed, and there were no reports of bacteremia or sepsis. Improvement in the International Prostate Symptom Score (IPSS) was observed in all cohorts. Given the small sample size of eight patients on PRX302 and two patients on placebo in each cohort, no statistically significant differences were observed.