• Primary diagnosis of obsessive-compulsive disorder (OCD) as per Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition as confirmed by the MINI at Screening; The duration of the subject's illness must be ≥ 1 year

• An inadequate response to current Standard of Care medication defined as selective serotonin reuptake inhibitor (excluding fluvoxamine) or clomipramine treatment at an adequate and stable dose for at least 8 weeks prior to screening and at least 12 weeks at baseline (adequate dose defined by USPI labeling); an inadequate response as defined per the MGH-TRQ-OCD, there has been minimal or no meaningful clinical benefit as perceived by the subject

• Determined by the investigator to be medically stable at baseline/randomization as assessed by medical history, physical examination, laboratory test results, and electrocardiogram testing. Subjects must be physically able and expected to complete the trial as designed