Adult Major Depressive Disorder

This is a phase 2, multicenter, randomized, double-blind, placebo-controlled, parallel-arm trial to assess the efficacy, safety, and tolerability of centanafadine once-daily (QD) extended-release (XR) capsules for the treatment of adult subjects diagnosed with Major Depressive Disorder (MDD) who have reported inadequate response to at least 1 but no more than 3 treatments for depression in their current major depressive episode. The trial will evaluate the efficacy and safety of centanafadine QD XR capsules as monotherapy or as adjunct to the selective serotonin reuptake inhibitor (SSRI), escitalopram. The trial will consist of up to a 28-day screening period, a 6-week double-blind treatment period, and a 7-day safety follow-up period. The trial is planned to be conducted on an outpatient basis with 336 subjects in the United States.