Evaluation of Efficacy and Safety of Milsaperidone as Adjunctive Therapy in Patients With Major Depressive Disorder

Who May Qualify: - Male or female patient 18 to 65 years of age, inclusive; - Meets DSM-5-TR criteria for MDD - Currently having an inadequate response to antidepressant therapy as confirmed by the Investigator using the Antidepressant Treatment Response Questionnaire (ATRQ) Who Should NOT Join This Trial: - Within the patients lifetime, has a confirmed DSM-5-TR psychiatric diagnosis other than MDD - Within 6 months of Screening, has a confirmed DSM-5-TR psychiatric diagnosis other than MDD - Within 12 months of Screening, has had any other psychiatric condition (other than MDD) that has been the main focus of treatment Always talk to your doctor about whether this trial is right for you.