Study of the Safety and Efficacy of Fixed Dose OPC-34712 as Adjunctive Therapy in the Treatment of Adults With Major Depressive Disorder (the Pyxis Trial)

Inclusion Criteria:

- Male or female subjects between 18 and 65 years of age, with diagnosis of major
depressive disorder, as defined by DSM-IV-TR criteria

- The current depressive episode must be equal to or greater than 8 weeks in duration

- Subjects must report a history for the current depressive episode of an inadequate
response to no more than three adequate antidepressant treatments

Exclusion Criteria:

- Females who are breast-feeding and/or who have a positive pregnancy test result prior
to receiving study drug

- Subjects who report an inadequate response to more than three adequate trials of
antidepressant treatments during current depressive episode at a therapeutic dose for
an adequate duration.

- Subjects with a current Axis I (DSM-IV-TR) diagnosis of: Delirium, dementia, amnestic
or other cognitive disorder, Schizophrenia, schizoaffective disorder, or other
psychotic disorder, Bipolar I or II disorder

- Subjects with a clinically significant current Axis II (DSM-IV-TR) diagnosis of
borderline, antisocial, paranoid, schizoid, schizotypal or histrionic personality
disorder