Patients with major depressive disorder (MDD) often have inadequate response to antidepressant treatment (ADT) requiring augmentation with other treatments. Cariprazine is a D3-preferring D3/D2 and serotonin 5-HT1A receptor partial agonist approved to treat schizophrenia and manic, mixed, and depressive episodes of bipolar I disorder. The efficacy of cariprazine as an adjunctive treatment for patients with MDD and inadequate response to ADT alone has been evaluated in phase 2/3 randomized, double-blind, placebo-controlled trials. Post hoc analyses of one phase 3 trial (NCT03738215) evaluated cariprazine + ADT for improving depressive symptoms in subgroups of patients categorized by 1) the level of response to ongoing ADT at baseline and 2) the number of ADTs associated with inadequate response during the current episode.

Patients were randomized to placebo + ADT (n=254), cariprazine 1.5 mg/d + ADT (n=252), or cariprazine 3 mg/d + ADT (n=253) for 6 weeks of double-blind treatment. Post hoc analyses evaluated change from baseline to week 6 in MADRS total score in subgroups of patients who had ≥25%–<50% or <25% response to ongoing ADT at baseline, and in subgroups of patients who had inadequate response to 1 or ≥2 ADTs in the current episode. Analyses used a mixed-effects model for repeated measures; least squares mean differences (LSMD) versus placebo with 95% confidence interval (95% CI) were calculated.

At baseline, 65.1% (n=486) of patients had an ADT response level between 25%–<50% and 34.9% (n=261) of patients had an ADT response level <25%. Mean MADRS total score reductions were greater for cariprazine 1.5 mg/d + ADT versus placebo + ADT in both ADT response subgroups (25%–<50% ADT response: -14.8 vs -11.9, LSMD [95% CI]=-2.3 [-4.2, -0.3]; <25% response to ADT: (-14.7 vs -11.7, LSMD [95% CI]=-2.6 [-5.5, 0.3]). For cariprazine 3 mg/d + ADT, mean change in MADRS total score was numerically greater versus placebo in both response subgroups (25%–<50% response=-14.2, LSMD [95% CI]=-1.5 [-3.5, 0.4]; <25% response= -12.3, LSMD [95% CI]=-0.74 [-3.6, 2.1]). Approximately 86% (n=644) and 14% (n=105) of patients in this study had inadequate response to 1 ADT or ≥2 ADTs, respectively, during the current episode. The LSMD (95% CI) in MADRS total score change for cariprazine 1.5 mg/d + ADT versus placebo + ADT was -2.3 (-4.1, -0.6) in the subgroup of patients with 1 previous ADT and -3.2 [-7.1, 0.8]) in the subgroup of patients with ≥2 previous ADTs. For cariprazine 3 mg/d + ADT, the LSMD (95% CI) in MADRS total score change versus placebo was -0.7 (-2.5, 1.0) in the 1 previous ADT subgroup and -4.7 (-8.8, -0.6) in the ≥2 previous ADTs subgroup.

In these post hoc analyses, cariprazine + ADT was associated with greater reductions in MADRS total score versus placebo regardless of the level of response to ongoing ADT at baseline or number of prior ADT failures in the current episode.

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