PLUS investigated the efficacy and safety of mirabegron add-on therapy in men with overactive bladder (OAB) symptoms receiving tamsulosin for underlying lower urinary tract symptoms attributable to benign prostatic hyperplasia (BPH).
Materials and Methods:
In this Phase 4 study, a 4-week, tamsulosin 0.4 mg run-in period was followed by a 12-week, randomized, double-blind, treatment period in which patients initially received mirabegron 25 mg or placebo add-on therapy. At 4 weeks, doses were titrated to mirabegron 50 mg or placebo equivalent. Efficacy endpoints: changes from baseline to end of treatment in mean number of micturitions/day (primary), mean volume voided (MVV)/micturition, number of urgency episodes/day, Total Urgency and Frequency Score (TUFS), and total International Prostate Symptom Score (IPSS; secondary). Safety: treatment-emergent adverse events (TEAEs) and post-void residual (PVR) volume and maximum urinary flow (Q max) assessments.
Of 676 men, most were ≥65 years old (380 [56.2%] patients). Tamsulosin plus mirabegron (TAM+MIRA) was statistically superior to tamsulosin plus placebo (TAM+PL) in reducing the mean number of micturitions/day (–2.00 versus –1.62, adjusted difference: –0.39, 95% confidence interval: –0.76, –0.02). Statistically superior results were noted for TAM+MIRA in MVV/micturition, urgency episodes/day, and TUFS (not IPSS). Higher overall TEAE rates were observed with TAM+PL, although higher rates of drug-related TEAEs were noted with TAM+MIRA. Urinary retention rates were higher in the TAM+MIRA group. PVR volume and Q max results were not clinically meaningful.
The results of PLUS underscore the utility of mirabegron add-on therapy to treat men with OAB symptoms receiving tamsulosin for BPH.