The study will be conducted in three periods:~Screening Period (up to 2 weeks) during which patient eligibility will be assessed;~Double-blind Treatment Period (6 weeks) in which all patients will be randomized to receive placebo or lumateperone 42mg/day in 1:1 ratio.~Safety Follow-up Period (1 week) in which all patients will return to the clinic for a safety follow-up visit approximately one week after the last dose of study treatment.
This is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, fixed-dose study in patients with a primary diagnosis of MDD according to criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) who have an inadequate response to ongoing ADT.