A Clinical Study That Will Measure How Well SEP-363856 Works and How Safe it is in Adults With Generalized Anxiety Disorder

This is a multicenter, randomized, double-blind, parallel-group, flexible dose, outpatient study evaluating the efficacy and safety of SEP-363856 flexibly dosed (50 - 75 mg/day) versus placebo over an 8-week Treatment Period in subjects with GAD. This study is projected to randomize approximately 434 subjects to 2 treatment groups (SEP-363856 \[50 - 75 mg/day\] or placebo) in a 1:1 ratio. Approximately 30 additional subjects (N = 15 per treatment group) are projected to enroll in the Japan Cohort. Treatment assignment will be stratified by country. Study drug will be taken at approximately the same time each evening at bedtime .