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 .

Inclusion criteria

(list is not all inclusive)

• Male or female subject between 18 to 65 years of age.
• Subject meets DSM-5 criteria for a diagnosis of Generalized Anxiety Disorder.
• Subject must be willing and able to comply with the study procedures and visit schedule and must be able to understand and follow verbal and written instructions.

Exclusion criteria

(list is not all inclusive)

• Subject has DSM-5-based diagnosis of any disorder other than Generalized Anxiety Disorder that was the primary focus of treatment within 12 months before Screening.
• Subjects who report an inadequate response to more than 3 antidepressant treatments
• Subject is at significant risk of harming self or others based on Investigator's judgment.
• Subject has any clinically significant unstable medical condition or any clinically significant chronic disease that in the opinion of the Investigator, would limit the subject's ability to complete and/or participate in the study.
• Female subject who is pregnant, lactating, or plans to get pregnant during the study.