ClinicalTrials.gov identifier: NCT02196506; EudraCT number: 2014-000062-22​​​.

Adjunctive brexpiprazole 2-3 mg/day improved symptoms of depression compared with adjunctive placebo in patients with MDD and an inadequate response to ADTs, and was well tolerated with no unexpected side effects.

Objective:Brexpiprazole is a serotonin-noradrenaline-dopamine agent that binds with high affinity to multiple serotonin, norepinephrine and dopamine receptors. In particular, Brexpiprazole is a partial agonist at dopamine D2/D3 and 5-HT1A receptors and an antagonist at 5-HT2A and norepinephrine alpha1B receptors.We assessed the efficacy and safety of brexpiprazole versus placebo as adjunctive therapy to anti-depressant therapy (ADT) in subjects with MDD who demonstrated inadequate response to ADT.Methods:This trial had 3 phases: a screening phase (7-28 days); a prospective phase (Phase A): 8-week, single-blind placebo plus an investigator-determined, open-label ADT; a randomized phase (Phase B): 6-week, double-blind, adjunctive brexpiprazole (2 mg/day) vs. placebo in patients with an inadequate response to ADT.The primary efficacy endpoint was the change from the end of Phase A (Week 8) to the end of Phase B (Week 14) in MADRS Total Score. The key secondary endpoint was the change in mean SDS score. Other secondary endpoints were mean change in CGI-S, IDS-R, HAMD and HAMA.Results:Of 379 randomized patients, completion rates at Week 14 were high (92.9%). Statistically significant improvements in mean MADRS Total score were observed for subjects receiving adjunctive brexpiprazole 2mg/day compared with placebo (p=0.0001) at endpoint. In addition, on all secondary endpoints Brexpiprazole showed a statistically significant advantage over placebo.Commonly reported adverse events in the brexpiprazole group (>5% and more than twice placebo) were weight gain (8.0%), akathisia (7.4%).Conclusions:Brexpiprazole was effective and well tolerated as adjunctive treatment for MDD patients with an inadequate response to ADT.

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Adjunctive brexpiprazole did not differentiate from ADT+placebo on the primary endpoint of full remission. A number of design elements in this previously untried study design may have contributed to the study result. Brexpiprazole was well tolerated.