Long-term Safety and Efficacy of Mirabegron and Solifenacin in Combination Compared with Monotherapy in Patients with Overactive Bladder: A Randomised, Multicentre Phase 3 Study (SYNERGY II).

Background: The long-term potential of solifenacin and mirabegron combination treatment for patients with overactive bladder (OAB) has not been previously assessed.
Objectives: To evaluate the safety and efficacy of solifenacin succinate 5mg plus mirabegron 50mg tablets (combination treatment) versus solifenacin or mirabegron monotherapy in patients with OAB over 12 mo.
Design, Setting, and Participants: Randomised, double-blind, multicentre, phase 3 trial (SYNERGY II) of patients with "wet" OAB symptoms (urinary frequency and urgency with incontinence) for ≥3 mo. The study was conducted from March 2014 to September 2016; with 1829 patients randomised. The full analysis set was comprised of 1794 patients.
Outcome Measurements and Statistical Analysis: The primary objective was safety, measured as treatment-emergent adverse events (TEAEs). Efficacy was measured as the change from baseline to the end of treatment in the mean number of incontinence episodes/24h and micturitions/24h.
Results and Limitations: The median age was 60 yr (range 19-86 yr) and 1434 patients (80%) were female. Overall, 856 patients (47%) experienced ≥1 TEAE. TEAE frequency was slightly higher in the combination group (596 patients, 49%; mirabegron 126 patients, 41%; solifenacin 134 patients, 44%). Serious TEAEs were reported by 67 patients (3.7%); one was considered possibly treatment-related (mirabegron group, atrial fibrillation). Dry mouth was the most common TEAE (combination 74 patients, 6.1%; solifenacin 18 patients, 5.9%; mirabegron 12 patients, 3.9%). Combination therapy was statistically superior to mirabegron and solifenacin for the number of incontinence episodes (vs mirabegron: adjusted mean difference [AMD] -0.5, 95% confidence interval [CI] -0.7 to -0.2, p<0.001; vs solifenacin: AMD -0.1, 95% CI -0.4 to 0.1, p=0.002) and micturitions (vs mirabegron: AMD -0.5, 95% CI -0.8 to -0.2, p<0.001; vs solifenacin: AMD -0.4, 95% CI -0.7 to -0.1, p=0.004).
Conclusions: Mirabegron and solifenacin combination treatment for OAB symptoms was well tolerated over 12 mo and led to efficacy improvements over each monotherapy. This innovative combination is a treatment option that could become widely used in the clinic.
Patient Summary: This study looked at the safety and efficacy of a combination of solifenacin succinate 5mg plus mirabegron 50mg tablets over 12 mo in patients with the overactive bladder (OAB) symptoms of increased urination frequency, heightened urgency to urinate, and unintentional passing of urine. We compared this treatment with solifenacin succinate 5mg or mirabegron 50mg alone, and found that the combination treatment was well tolerated by patients and led to greater improvements in symptoms. This novel combination could be an improved treatment option in the clinical setting for patients with OAB. This study is registered at ClinicalTrials.gov as NCT02045862.
(Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)