Brexpiprazole for schizophrenia and as adjunct for major depressive disorder: a systematic review of the efficacy and safety profile for this newly approved antipsychotic - what is the number needed to treat, number needed to harm and likelihood to be helped or harmed?

OBJECTIVE: To describe the efficacy, tolerability and safety of brexpiprazole for the treatment of schizophrenia and as adjunct for major depressive disorder (MDD). DATA SOURCES: The pivotal registration trials were accessed by querying http://www.ncbi.nlm.nih.gov/pubmed/ and http://www.clinicaltrials.gov, for the search terms 'brexpiprazole' OR 'OPC-34712', and by also querying the EMBASE (Elsevier) commercial database for clinical poster abstracts, and by asking the manufacturer for copies of posters presented at congresses. Product labelling provided additional information. STUDY SELECTION: All available clinical reports of studies were identified. DATA EXTRACTION: Descriptions of the principal results and calculation of number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were extracted from the available study reports and other sources of information. DATA SYNTHESIS: Brexpiprazole is a new dopamine D2 receptor partial agonist that received approval for the treatment of schizophrenia and for adjunctive use for the treatment of MDD based on a clinical trial development programme that included two pivotal Phase III trials of brexpiprazole monotherapy in acute schizophrenia, and two pivotal Phase III trials of adjunctive brexpiprazole in acute MDD in patients who demonstrated inadequate response to standard antidepressant therapy. In addition, results from a 52-week relapse prevention/maintenance randomised placebo-controlled withdrawal study in patients with schizophrenia are available. In these trials, brexpiprazole was administered once daily and titrated to target doses. The recommended dose for the treatment of schizophrenia is 2-4 mg/day and that for MDD, 2 mg/day. Pooling together all the available data for the recommended target dose of brexpiprazole for acute schizophrenia from the above studies, the percentage of responders is 45.5% vs. 31.0% for placebo, yielding a NNT of 7 (95% CI 5-12). In the relapse prevention/maintenance trial, significantly fewer patients relapsed in the brexpiprazole group compared with placebo (13.5% vs. 38.5%), resulting in a NNT of 4 (95% CI 3-8). When the results for brexpiprazole 1, 2 and 3 mg from the two Phase III MDD trials are pooled together, 23.2% of the patients receiving brexpiprazole were responders, vs. 14.5% for placebo, yielding a NNT of 12 (95% CI 8-26). Brexpiprazole was well tolerated - for schizophrenia, discontinuation rates because of an adverse event (AE) were overall lower for patients receiving brexpiprazole vs. placebo, and for MDD a total of 3% of brexpiprazole-treated patients and 1% of placebo-treated patients discontinued because of AEs, resulting in a NNH of 53 (95% CI 30-235). Although the most commonly encountered AE noted in product labelling was akathisia (5.5% in the acute schizophrenia trials and 8.6% in the MDD trials), differences from placebo were small, generating a non-significant NNH of 112 for patients with schizophrenia and a modest NNH of 15 (95% CI 11-23) for patients with MDD. Short-term weight gain appears modest; however, more outliers with an increase of ≥ 7% of body weight were evident in open-label 52-week safety studies. Effects on glucose and lipids were small. Minimal effects on prolactin were observed, and no clinically relevant effects on the ECG QT interval were evident.
CONCLUSIONS: Clinical trials of brexpiprazole support its efficacy at the recommended target dose of 2-4 mg/day for the treatment of schizophrenia, and at the recommended target dose of 2 mg/day as adjunct to antidepressant medication for the treatment of MDD. Head-to-head comparisons with other available agents among patients with schizophrenia and MDD in the 'real world' are needed.