 - The participants depressive symptoms have previously demonstrated nonresponse to: Esketamine or ketamine in the current major depressive episode per clinical judgment, or all of the 4 oral antidepressant treatment options available for the double-blind induction Phase Duloxetine, Escitalopram, Sertraline, and Venlafaxine extended release XR in the current major depressive episode based on MGH-ATRQ, or an adequate course of treatment with electroconvulsive therapy ECT in the current major depressive episode, defined as at least 7 treatments with unilateral ECT 