Sophiris Bio announces successful Phase III results for PRX 302 for treatment of benign prostatic hyperplasia

Sophiris Bio a biopharmaceutical company developing PRX 302 (topsalysin) for the treatment of urological diseases, announced final results from its Phase III "PLUS-1" study of PRX 302 as a treatment for lower urinary tract symptoms of benign prostatic hyperplasia (BPH, enlarged prostate).

PRX 302 demonstrated a statistically significant improvement in International Prostate Symptom Score (IPSS) total score from baseline over 12 months compared to the vehicle-only control group (7.60 vs. 6.58 point overall improvement; p = 0.043), the primary endpoint of the study. PRX302 continues to demonstrate a favourable safety profile, with no evidence of any treatment-related sexual or cardiovascular side effects.

The primary efficacy endpoint of the IPSS total score change from baseline over 52 weeks was analysed, per guidance from the FDA, using the repeated measures linear mixed model applied to the modified intent-to-treat population of every patient randomised and dosed with study drug. The 7.60-point overall improvement for the PRX 302 group was statistically significantly superior to the 6.58 point improvement in the vehicle-only group (p = 0.043). In a secondary efficacy analysis of IPSS total score using an ANCOVA model and LOCF (Last Observation Carried Forward) to impute missing post-baseline data, the improvement in IPSS for PRX 302 was well sustained over the 52 weeks following the single administration. The maximal effect of 8.31 points improvement in IPSS vs vehicle 6.89 points (p = 0.012) was achieved at Week 18 with 8.04 points of improvement for PRX 302 still remaining at Week 52 vs 6.64 points for patients treated with vehicle only (p = 0.022) representing an end-of-study preservation of 97% of the peak benefit.

Comment: The first patients have been dosed in a Phase IIa proof of concept trial of PRX 302 as a treatment for localised low to intermediate risk prostate cancer.