A Phase III, multi-center, randomized, 24 week, double-blind, parallel-group, placebocontrolled study to evaluate efficacy and safety of RO4917838 in stable patients with persistent, predominant negative symptoms of schizophrenia treated with antipsychotics followed by a 28 week, double-blind treatment period. - ND

INTERVENTION: Product Name: GlyT1(1) Pharmaceutical Form: Film‐coated tablet INN or Proposed INN: non ancora disponibile CAS Number: 845614‐11‐1 Current Sponsor code: RO4917838/F18 Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 10‐ Pharmaceutical form of the placebo: Film‐coated tablet Route of administration of the placebo: Oral use Product Name: GlyT1(1) Pharmaceutical Form: Film‐coated tablet INN or Proposed INN: non ancora disponibile CAS Number: 845614‐11‐1 Current Sponsor code: RO4917838/F18 Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 20‐ Pharmaceutical form of the placebo: Film‐coated tablet Route of administration of the placebo: Oral use CONDITION: Treatment of negative symptoms for patients with schizophrenia treated with antipsychotics. ; MedDRA version: 9.1 Level: LLT Classification code 10039626 PRIMARY OUTCOME: Main Objective: • Evaluate efficacy of 24 weeks treatment with RO4917838 in the PANSS negative symptom factor score in patients with persistent, predominant negative symptoms of schizophrenia treated with antipsychotics; • Evaluate safety and tolerability of 24 weeks treatment with RO4917838 in patients with persistent, predominant negative symptoms of schizophrenia treated with antipsychotics. Primary end point(s): Primary Efficacy: • Mean change from baseline in the PANSS negative symptom factor score at week 24. Secondary Objective: • To evaluate efficacy of 24 weeks treatment with RO4917838 in personal and social functioning using PSP total score in patients with persistent, predominant negative symptoms of schizophrenia treated with antipsychotics. INCLUSION CRITERIA: A patient may be included into Prospective Stabilization Period if the answer to all of the following statements is “yes”: Demographic 1. Male and female patients, aged 18 and above. 2. Female patients who are not either surgically sterile (e.g., tubal ligation or removal of ovaries or uterus) or post‐menopausal (no spontaneous menstrual periods for at least one year confirmed by a negative hormone panel) must agree for the entire study duration to use one of the following forms of contraception: (1) systemic hormonal treatment (2) an IUD which was implanted at least 2 months prior to screening or (3) ``doublebarrier`` contraception (condom, diaphragm and spermicide are each considered a barrier), or (4) agree to remain sexually abstinent during the entire study period (when contraception is not acceptable for cultural or religious beliefs). Procedural 3. Sign written informed consent after the scope and nature of the investigation have been explain