A Study of Bitopertin (RO4917838) in Combination With Selective Serotonin Reuptake Inhibitors (SSRIs) in Participants With Obsessive-Compulsive Disorder (OCD)

A Phase II, Multicenter, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study to Evaluate Efficacy and Safety of RO4917838 in Combination With Selective Serotonin Reuptake Inhibitors in Patients With Obsessive Compulsive Disorder

This multicenter, randomized, double-blind, parallel-group, placebo-controlled study will evaluate the efficacy and safety of bitopertin in combination with SSRI in participants with obsessive-compulsive disorder. Participants will be randomized to receive either bitopertin 30 milligrams (mg) or bitopertin 10 mg or placebo orally daily in addition to their background therapy with an SSRI. Participants will be allocated to one of two strata. Participants in Stratum 1 will start study drug on Day 1. Participants in Stratum 2 will receive placebo from Day 1 (placebo lead-in) and will then start study drug at the Week 2 visit. Participants in both strata will receive the study drug in addition to their background therapy with an SSRI until Week 16.

Inclusion Criteria:

• Primary diagnosis of OCD as per Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR)
• On a stable dose of SSRI for at least 8 weeks prior to screening an between screening and Day 1
• An insufficient response to current treatment with an SSRI given at an adequate dose for at least 12 weeks prior to Day 1
• Females who are not postmenopausal or surgically sterile and who have (or may have) male sexual partners must agree to use two adequate methods of contraception as defined by protocol from the start of screening until 90 days after the last dose of study drug

Exclusion Criteria:

• Primary OCD symptom of hoarding
• More than two unsatisfactory trials within the last 2 years with different serotonin reuptake inhibitors (not including the current treatment with an SSRI) given in an adequate dose for at least 12 weeks
• Failure of more than three augmentation therapies within the last 2 years
• Undergoing acute behavioral therapy or having acute behavioral therapy that was completed less than 4 weeks prior to Day 1
• Any primary DSM-IV-TR Axis I disorder other than OCD
• Current or prior history of bipolar disorder, schizophrenia or other psychotic disorders, schizoaffective disorder, autism or autistic spectrum disorders, borderline personality disorder, or Gilles de la Tourette syndrome if symptoms have persisted into adulthood
• Any eating disorder within the last 6 months
• History of DSM-IV-TR-defined substance dependence and/or substance abuse in the last 6 months, with the exception of nicotine
• Previous treatment with bitopertin or another Glycine transporter 1 inhibitor
• Positive urine drug screening for cannabis, amphetamines (including 3,4-methylenedioxymethamphetamine [MDMA]/ecstasy), cocaine, barbiturate, and/or opiates
• Prior or current general medical condition that may impair cognition or other neuropsychiatric functioning
• Body mass index less than (<) 18.5 kilogram per square meter (kg/m^2) or greater than (>) 40 kg/m^2
• Pregnant or lactating women