A Phase II Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy, Safety, and Tolerability of Orally Administered BI 409306 During a 28-week Treatment Period as Adjunctive Therapy to Antipsychotic Treatment for the Prevention of Relapse in Patients With Schizophrenia.

The objective of the study is to investigate the efficacy, safety and tolerability of BI 409306 once daily compared with placebo given for 28 weeks in patients with schizophrenia on antipsychotic treatment. The study is designed to show superiority of BI 409306 over placebo in preventing relapse of schizophrenia symptoms.