A Randomized Double-blind Placebo-controlled Phase 2 Dose-ranging Study of OnabotulinumtoxinA in Men with Benign Prostatic Hyperplasia

BackgroundBotulinum toxin treatment has been investigated as a minimally invasive alternative to oral medications in men with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (LUTS/BPH).ObjectiveTo explore the efficacy of onabotulinumtoxinA 100 U, 200 U, and 300 U versus placebo in men with LUTS/BPH in a phase 2 dose-ranging study.Design, setting, and participantsA multicenter double-blind randomized, placebo-controlled 72-wk study enrolled men ≥50 yr of age with LUTS/BPH, International Prostate Symptom Score (IPSS) ≥12, total prostate volume (TPV) 30–100 ml, and maximum flow rate (Qmax) 5–15 ml/s.InterventionSingle transperineal (n = 63) or transrectal (n = 311) administration of placebo (n = 94) or onabotulinumtoxinA 100 U (n = 95), 200 U (n = 94), or 300 U (n = 97) into the prostate transition zone.Outcome measurements and statistical analysisThe primary efficacy end point was a change from baseline in IPSS at week 12. Secondary end points were Qmax, TPV, and transition zone volume (TZV). Analysis of covariance and the Cochran-Mantel-Haenszel method assessed the efficacy and proportion of IPSS responders. Adverse events (AEs) were assessed.Results and limitationsSignificant improvements from baseline in IPSS, Qmax, TPV, and TZV were observed for all groups, including placebo, at week 12 (p < 0.001), with no significant differences between onabotulinumtoxinA and placebo. However, in an exploratory post hoc analysis, a significant reduction in IPSS versus placebo was observed with onabotulinumtoxinA 200 U in prior α-blocker users (n = 180) at week 12. AEs were comparable across all groups.ConclusionsReductions in LUTS/BPH symptoms were seen in all groups, including placebo, with no significant between-group differences owing to a large placebo effect from the injectable therapy. The findings from the post hoc analysis in men previously treated with α-blockers will be further explored in an appropriately designed study.Trial registrationhttp://www.Clinical Trials.gov; NCT00284518.