Pomaglumetad methionil: No significant difference as an adjunctive treatment for patients with prominent negative symptoms of schizophrenia compared to placebo

This study tested whether treatment with pomaglumetad methionil (LY2140023 monohydrate), a metabotropic glutamate receptor 2/3 agonist compared with placebo (PBO), when added to a fixed-dose second-generation antipsychotic (SGA) demonstrated significantly greater reduction of negative symptoms, as assessed by the 16-item Negative Symptom Assessment scale (NSA-16), in patients with schizophrenia. This parallel-group, 16-week study enrolled adults with schizophrenia who were receiving standard of care (SOC) therapy, which included ≥ 3 months treatment with one of four SGAs: aripiprazole, olanzapine, risperidone, or quetiapine. Patients received either 20 mg of twice daily LY2140023 monohydrate (LY2140023) or concurrent PBO SGA. The primary efficacy measure was change from baseline to final visit in NSA-16 total score. Secondary measures included additional measures of efficacy, cognition, and assessments of safety. Of 352 patients screened, 167 were randomly assigned to treatment, and 110 patients completed the study. Patients treated with LY2140023 and SOC failed to demonstrate a statistically significant improvement over patients treated with PBO and SOC on NSA-16 total score at endpoint or at any point during the study (all p > 0.131). Changes in secondary efficacy measures were not significantly different between groups at endpoint. With the exception of vomiting which was greater in the LY2140023 group, there were no statistically significant differences in safety and tolerability measures. This study found no benefit of adjunctive LY2140023 versus PBO for negative symptoms in patients with schizophrenia receiving treatment with SOC. LY2140023 was generally well-tolerated in these patients.