A Randomized, Parallel-Group, Double-Blind, Placebo-Controlled, Monotherapy Study of the Efficacy, Safety, and Tolerability of SPT-300 in Adults With Major Depressive Disorder (MDD), With or Without Anxious Distress

Inclusion Criteria: * Participant is a male or female between 18 and 65 years of age, inclusive willing and able and have capacity to provide written informed consent. * Participants must have a primary diagnosis of MDD. Participants with a diagnosis of comorbid generalized anxiety disorder, social anxiety disorder, or panic disorder (with or without agoraphobia) may be included if not the focus of treatment over the past 6 months prior to Screening and the Investigator considers MDD to be the primary diagnosis at Screening and Baseline. * Eligible participants must have a current depressive…