A Phase 2 Trial of OPC-64005 for Major Depressive Disorder

Inclusion Criteria: * Patients with a DSM-5 classification-based diagnosis of "major depressive disorder, single episode" or "major depressive disorder, recurrent episode" with the current episode persisting for ≥4 weeks to ≤1 year * Patients with a total score of ≥18 on the 17-item Hamilton Rating Scale for Depression (HAM-D) Exclusion Criteria: * Patients with a diagnosis of any of the following diseases according to DSM-5 Neurocognitive disorders, history or complication of schizophrenia spectrum or other psychotic disorder, history or complication of bipolar and related disorders, feeding and eating disorders, obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, personality disorders, neurodevelopmental disorders, substance-related and addictive disorders (within 180 days prior to informed consent) * Patients exhibiting mood-incongruent psychotic features in the current major depressive episode * Patients who, in the opinion of the investigator or subinvestigator, are judged to have treatment-resistant depression, ie, a certain degree of therapeutic effect is not obtained by administration of 2 or more antidepressants having different mechanisms of action at sufficient doses for at least 6 weeks for the current major depressive episode * Patients receiving augmentation treatment, such as antipsychotics, for the current major depressive episode (excluding the use of sulpiride for depression/depressive state or gastric/duodenal ulcer)