Efficacy of adjunctive brexpiprazole on symptom clusters of major depressive disorder: A post hoc analysis of four clinical studies

Background: Major depressive disorder (MDD) is a clinically heterogenous condition and its treatment should be individualized according to the presence of particular symptom clusters. The aim of this pooled analysis was to investigate the effects of adjunctive brexpiprazole on different symptom clusters in MDD. Methods: Data were included from four similarly designed, short-term, randomized, double-blind, placebo -controlled studies of adjunctive brexpiprazole in adults with MDD and inadequate response to 2-4 antidepressant treatments (ADTs), including 1 administered by investigators. Mean changes from baseline and Cohen's d effect sizes (ES) versus placebo were determined for the following Montgomery-Asberg Depression Rating Scale symptom clusters: core, anhedonia, dysphoria, retardation, vegetative, loss of interest, and lassitude. Results: Over 6 weeks, ADT + brexpiprazole 2 mg (n = 486) showed greater improvement than ADT + placebo (n = 585) for all symptom clusters: core (ES = 0.36; p < 0.0001), anhedonia (ES = 0.43; p < 0.0001), dysphoria (ES = 0.27; p < 0.0001), retardation (ES = 0.32; p < 0.0001), vegetative (ES = 0.29; p < 0.0001), loss of interest (ES = 0.30; p < 0.0001), and lassitude (ES = 0.33; p < 0.0001). Improvements of similar magnitude were observed for ADT + brexpiprazole 2-3 mg (n = 770) versus ADT + placebo (n = 788) (ES = 0.24-0.38; all clusters p < 0.0001). In most cases, improvement over ADT + placebo was observed from Week 1 onwards. Limitations: Post hoc analysis with no adjunctive active comparator. Conclusions: Patients receiving adjunctive brexpiprazole versus adjunctive placebo showed improvements across a range of MDD symptom clusters. Improvements appeared early (generally from Week 1) and were maintained over 6 weeks. These data indicate that adjunctive brexpiprazole may benefit multiple subtypes of patient with MDD and inadequate response to ADTs.