Efficacy and safety of evenamide, a glutamate modulator, added to a second-generation antipsychotic in inadequately/poorly responding patients with chronic schizophrenia: Results from a randomized, double-blind, placebo-controlled, phase 3, international clinical trial.

Background: Evenamide, a glutamate modulator, is currently in phase 3 of development as add-on treatment to antipsychotics in patients with inadequate response or treatment-resistant schizophrenia. This study was designed to determine if patients with chronic schizophrenia inadequately responding to a second-generation antipsychotic would benefit from add-on treatment with evenamide at a dose of 30 mg bid.

Methods: Study 008A was a prospective, 4-week, randomized, double-blind, placebo-controlled study evaluating the safety, tolerability, and efficacy of oral doses of evenamide of 30 mg bid in patients with chronic schizophrenia treated at stable therapeutic doses of a second-generation antipsychotic. Outpatients aged ≥18 years, both males and females, with a diagnosis of schizophrenia (DSM-V), who had been receiving antipsychotics for at least 2 years at stable doses, but still symptomatic (PANSS 70-85, CGI-S 4-6, predominant positive symptoms), were eligible for the study. Patients were randomised equally to evenamide 30 mg or placebo, given bid, after completing a 21-day screening period. The primary outcome (change from baseline in PANSS total score) was assessed weekly, with the primary endpoint at 4 weeks.

Results: A total of 291 patients were enrolled, of which 11 (3·8%) discontinued prematurely, overall. Add-on treatment with evenamide was associated to a statistically significant (the absolute difference of the two treatment groups for the PANSS Total at Day 29, primary efficacy endpoint, was = 2·5 [p-value<0.05] that is associated with a Cohen's d effect size = 0·33) and clinically meaningful benefit compared to placebo across all efficacy measures, and was well tolerated.

Conclusion: The demonstration of statistically significant and clinically meaningful benefit of evenamide, a glutamate modulator, as add-on treatment in patients with chronic schizophrenia inadequately responding to their second-generation antipsychotic may represent a new treatment paradigm for this population.