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Bitopertin modestly effective for treatment-resistant schizophrenia

Bitopertin, a selective GlyT1-mediated glycine-reuptake inhibitor, may be modestly effective for adjunctive treatment of schizophrenia among individuals with suboptimal response to antipsychotics, according to recent findings.

“Many patients with schizophrenia require high doses of medication for their ongoing psychotic symptoms. Glutamate theories and findings from studies showing efficacy of sarcosine, an endogenous, non-selective glycine-reuptake inhibitor mediated by GlyT1, offer an alternative approach,” Dragana Bugarski-Kirola, MD, medical director at Roche, and colleagues wrote.

To assess efficacy of bitopertin as adjunctive treatment for ongoing antipsychotic therapy in schizophrenia, researchers conducted three phase 3, randomized, double-blind, placebo-controlled multisite studies in outpatient clinics in Asia, Europe, North and South America. Study participants (n = 1,772) were randomly assigned to 12 weeks of placebo or one of two fixed doses of oral, once-daily bitopertin in addition to current antipsychotic treatment. Participants received either 10 mg or 20 mg of bitopertin or 5 mg or 10 mg of bitopertin.

After 12 weeks of treatment, an additional 40 weeks of double-blind treatment was conducted to assess maintenance, followed by a randomized 40-week washout period to determine withdrawal effects.

One of the three studies met the primary endpoint, in which Positive and Negative Syndrome Scale (PANSS) Positive Symptom Factor scores significantly differed from placebo at week 12 among participants who received 10 mg of bitopertin (P = .0028).

Participants who received 5 mg, 10 mg and 20 mg of bitopertin in the other two studies did not exhibit significant improvements compared with placebo.

Placebo responses varied across study sites and may have contributed to differences in efficacy, according to researchers.

One death by suicide was attributed to study treatment.

Serious adverse events were low across all study groups and sites.

These findings suggest that bitopertin may have modest efficacy for suboptimal responders to antipsychotic therapy, according to researchers. – by Amanda Oldt

Disclosure: Bugarski-Kirola reports no relevant financial disclosures. Please see the study for a full list of relevant financial disclosures.