The purpose of this study is to evaluate the safety and tolerability of brexpiprazole as adjunctive treatment in an elderly population with major depressive disorder and an inadequate response to antidepressant treatment

Main Inclusion Criteria:

• • The patient is a man or woman aged ≥65 yrs

  • The patient has Major Depressive Disorder according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR™).
  • The patient has an inadequate response to at least one adequate antidepressant treatment in the current Major Depressive Episode (MDE).
  • The patient has had the current MDE for ≥8 weeks
  • The patient is currently treated with a protocol specified ADT for at least 6 weeks
  • The patient is judged to benefit from adjunctive treatment with brexpiprazole according to the clinical opinion of the investigator.
  • Montgomery and Åsberg Depression Rating Scale (MADRS) total score > 18 at screening and baseline
  • Clinical Global Impression - Severity (CGI-S) total score ≥3 at screening and baseline

Main Exclusion Criteria:

• • The patient has a clinically significant unstable illness

  • The patient has newly diagnosed or unstable diabetes
  • The patient has a Mini Mental State Exam (MMSE) score <24
  • The patient has received Transcranial Magnetic Stimulation (TMS) and/or electroconvulsive therapy (ECT) less than 6 months prior to the Screening.
  • The patient, in the opinion of the investigator or based on Columbia-Suicide Severity Rating Scale (C-SSRS) Suicidal Ideation and behaviour rating, is at significant risk of suicide

Other protocol defined inclusion and exclusion criteria may apply