This is an outpatient, 2-arm, Phase 3, multicenter, randomized, double-blind, placebo-controlled study to assess the efficacy and safety of REL-1017 once daily (QD) as an adjunctive treatment of Major Depressive Disorder in patients with inadequate response to ongoing background antidepressant treatment. Eligible patients will continue to take their background antidepressant therapy and be randomized in a 1:1 ratio to treatment with REL-1017 or placebo for a 4 week treatment period.
