A Randomized, Placebo-Controlled Study of the Efficacy and Safety of Fixed-Dose Brexpiprazole 2 mg/d as Adjunctive Treatment of Adults With Major Depressive Disorder

OBJECTIVE: To assess the efficacy, safety, and tolerability of brexpiprazole as adjunct to antidepressant treatment (ADT) in adults with major depressive disorder (MDD) and inadequate response to ADTs. METHODS: Outpatients with inadequate response to 1-3 ADTs during their current depressive episode (DSM-IV-TR criteria) were administered prospective, open-label ADT. Those patients with inadequate response to prospective ADT were randomized to double-blind, adjunctive brexpiprazole 2 mg/d or placebo. The primary efficacy end point was the change from baseline (randomization) to week 6 in Montgomery-Åsberg Depression Rating Scale (MADRS) total score. Key secondary efficacy end points were the change in Sheehan Disability Scale (SDS) mean score for all patients and the change in MADRS total score for subgroups with minimal response to prospective ADT and DSM-5-defined anxious distress. The study was conducted from July 2014 to May 2016. RESULTS: Adjunctive brexpiprazole (n = 191) improved MADRS total score from baseline to week 6 versus placebo (n = 202; least squares mean difference 95% confidence limits: -2.30 -3.97, -0.62; P = .0074). There was no separation between groups for the SDS mean score (-0.22 -0.66, 0.23; P = .33). Adjunctive brexpiprazole also improved MADRS total score versus placebo in the subgroups with minimal response to prospective ADT (-2.25 -4.23, -0.27; P = .026) and anxious distress (-2.98 -5.24, -0.72; P = .0099). Treatment with adjunctive brexpiprazole was well tolerated with no unexpected side effects. CONCLUSIONS: This study adds to the substantial body of evidence for the efficacy and tolerability of brexpiprazole as adjunctive treatment in patients with MDD and inadequate response to ADTs. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02196506; EudraCT number: 2014-000062-22​​​.