AZD8529, a positive allosteric modulator at the mGluR2 receptor, does not improve symptoms in schizophrenia: A proof of principle study.

INTRODUCTION

Activation of metabotropic glutamate (mGluR2/3) receptors has been proposed as an alternative mechanism to dopaminergic-based antipsychotics to correct glutamatergic deficits hypothesized to underlie schizophrenia symptoms. This study investigates the efficacy and safety of AZD8529, a selective positive allosteric modulator (PAM) at the mGlu2 receptor, in symptomatic patients with schizophrenia.

METHODS

Patients were randomized to receive AZD8529 40 mg, risperidone 4 mg, or placebo as monotherapy. Treatment lasted for 28 days, and clinical efficacy was assessed using Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression (CGI) scores.

RESULTS

There were no significant differences between patients treated with AZD8529 versus placebo in change from baseline to endpoint in PANSS total, negative and positive symptom subscale, or CGI-S scores. In contrast, risperidone demonstrated significant efficacy relative to placebo.

CONCLUSION

These results do not support a role for the mGluR-2 PAM AZD8529 as an antipsychotic and indicate that positive modulation of mGluR type 2 receptors alone is not sufficient for antipsychotic effects in acutely ill schizophrenia patients.