Study to Evaluate the Effect of AFQ056 in Obsessive Compulsive Disorder (OCD) Patients Resistant to Selective Serotonin Reuptake Inhibitor (SSRI) Therapy

Inclusion Criteria: * Male and female , non-smokers patients aged between 18 to 65 years (inclusive), * A primary diagnosis of obsessive-compulsive disorder (OCD) as per Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR 4th ed, year 2000), as confirmed by an Independent Rater. * Be on a stable appropriate dose of selective serotonin reuptake inhibitor (SSRI) treatment for at least 12 weeks prior to Baseline. * Have an insufficient response to current SSRI treatment (as per Inclusion Criterion 4) and confirmed by an Independent Rater. * Have a Yale-Brown Obsessive Compulsive Scale (Y-BOCS) of score ≥ 16 at Screening (and confirmed by an Independent Rater). * Patient must have their eligibility confirmed following the remote interview conducted by the Independent Rater. * Able to communicate well with the investigator, to understand and comply with the requirements of the study. Exclusion Criteria: * Diagnosis of primary OCD symptom of hoarding. * Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they are using effective methods of contraception (not including oral contraceptives) during dosing and for 30 days after last dosing of study medication. * History of more than two unsatisfactory trials with different SSRI within a period of 2 years prior to screening (not including the current treatment with SSRI's given in an adequate dose for at least 12 weeks). * Diagnosed with any primary DSM-IV-TR Axis I disorder other than OCD (as confirmed by an Independent Rater); with the exception of depression. * History of eating disorder (e.g. anorexia, bulimia) according to DSMIV within the last 6 months prior to Screening, (as confirmed by an Independent Rater). * Diagnosed with antisocial personality disorder (DSM-IV-TR Axis II), as confirmed by an Independent Rater. * Has current or past medical history of bipolar disorder, schizophrenia or other psychotic disorders, schizoaffective disorder, autism or autistic spectrum disorders, borderline personality disorder, within the last 6 months prior to Screening. * Smokers (use of tobacco products in the previous 3 months). * History of hallucinations/psychosis that would require antipsychotic treatment or DSM-IV criteria being met * Score "yes" on item 4 or item 5 of the Suicidal Ideation section of the C-SSRS, if this ideation occurred in the past 6 months, or "yes" on any item of the Suicidal Behavior section, except for the "Non- Suicidal Self-Injurious Behavior" (item also included in the Suicidal Behavior section), if this behavior occurred in the past 2 years.