An Adaptive, Phase IIb/III, Double-Blind, Randomized, Placebo-Controlled, Multi-Center Study of the Safety and Efficacy OF NaBen® , A D-Amino Acid Oxidase Inhibitor, as an Add-on Treatment for Schizophrenia in Adolescents

• Male or female subjects who are between 12 and 17 years of age inclusive

• Physician confirmed DSM-IV or -V diagnosis of schizophrenia based on MINI International Neuropsychiatric Interview for Schizophrenia and Psychotic Disorders Studies for Children and Adolescents, version 6.0 (MINI-KID, Version 6.0)

• Are clinically stable with residual symptoms, defined as a total score of ≥ 60 of PANSS and a score of ≥ 40 for SANS

• An unchanged antipsychotic medication regimen for at least eight (8) weeks prior to randomization into the study and expected to remain unchanged during the study (longer for depot or long-acting antipsychotics: ten (10) months for Aripiprazole (Maintena®) and Paliperidone (Xeplion®); six (6) months for Olanzapine pamoate monohydrate (Zypadhera®); and at least 6 times duration of the reported half life or minimum four (4) months for other depot or long-acting antipsychotics)

• In good general physical health and all physical exam, neurological exam and laboratory assessments (urine/blood routine, biochemical tests and ECG) are clinically unremarkable per the investigator

• Subject has a negative urine illicit drug screening test

• Subject understands and is willing to sign the Informed Assent Form (IAF) prior to study entry and agrees to be available for all the study visits

• The subject's guardian understands and is willing to sign the Informed Consent Form (ICF) prior to study entry and agrees to be available for all the study visits

• Must not be a danger to self or others and must have family support available to be maintained as outpatients