Effect of the mGluR5-NAM Basimglurant on Behavior in Adolescents and Adults with Fragile X Syndrome in a Randomized, Double-Blind, Placebo-Controlled Trial: FragXis Phase 2 Results.

Preclinical data suggest that inhibition of the metabotropic glutamate receptor 5 (mGluR5) receptor might hold therapeutic benefits in Fragile X syndrome (FXS). Treatment of Fmr1 knockout mice with mGluR5-negative allosteric modulators (NAMs) has been reported to correct a broad range of phenotypes related to FXS. The early short-term clinical trials with mGluR5 NAMs, including basimglurant, assessing the effects in individuals with FXS, were supportive of further exploration in larger, well-controlled trials. We evaluated basimglurant, a potent and selective mGluR5 NAM, in a 12-week, double-blind, parallel-group study of 183 adults and adolescents (aged 14-50, mean 23.4 years) with FXS. Individuals with an FMR1 full mutation were randomized to placebo or one of two doses of basimglurant. The primary efficacy endpoint was the change from baseline in behavioral symptoms using the Anxiety Depression and Mood Scale (ADAMS) total score. All treatment arms showed marked behavioral improvements from baseline to week 12 with less improvement in the basimglurant 1.5 mg arm than placebo; however, basimglurant 0.5 mg was inferior to placebo in the ADAMs total score. Treatment with basimglurant was overall well-tolerated. A higher incidence of adverse events classified as psychiatric disorders were reported in patients treated with basimglurant, including three patients with hallucinations or psychosis. In this phase 2 clinical trial, basimglurant did not demonstrate improvement over placebo. Evaluation of the overall risk-benefit in younger patient populations is an important consideration for the design of potential further investigations of efficacy with this class of medications.

Effect of bitopertin, a glycine reuptake inhibitor, on negative symptoms of schizophrenia: a randomized, double-blind, proof-of-concept study.

IMPORTANCE: In schizophrenia, the severity of negative symptoms is a key predictor of long-term disability. Deficient signaling through the N-methyl-D-aspartate receptor is hypothesized to underlie many signs and symptoms associated with schizophrenia in particular negative symptoms. Glycine acts as an N-methyl-D-aspartate receptor coagonist. Blockade of the glycine transporter type 1 to inhibit glycine reuptake and elevate synaptic glycine concentrations represents an effective strategy to enhance N-methyl-D-aspartate receptor transmission. OBJECTIVE: To determine the efficacy and safety of bitopertin (RG1678), a glycine reuptake inhibitor, in patients with schizophrenia and predominant negative symptoms who were stable while taking an antipsychotic treatment. DESIGN, SETTING, AND PARTICIPANTS: This randomized, double-blind, placebo-controlled, phase 2 proof-of-concept trial involved 323 patients with schizophrenia and predominant negative symptoms across 66 sites worldwide. INTERVENTIONS: Bitopertin (10, 30, or 60 mg/d) or placebo added to standard antipsychotic therapy for a treatment duration of 8 weeks. MAIN OUTCOMES AND MEASURES: Change from baseline in the Positive and Negative Syndrome Scale negative factor score. RESULTS: In the per-protocol population, 8 weeks of treatment with bitopertin was associated with a significant reduction of negative symptoms in the 10-mg/d (mean [SE] reduction in negative symptoms score, -25% [2%]; P = .049) and 30-mg/d (mean [SE], -25% [2%]; P = .03) bitopertin groups, a significantly higher response rate and a trend toward improved functioning in the 10-mg/d group when compared with placebo (mean [SE], -19% [2%]). Results reached trend-level significance in the intent-to-treat population. Estimates of bitopertin binding to glycine transporter type 1 showed that low to medium levels of occupancy yielded optimal efficacy in patients, consistent with findings in preclinical assays. CONCLUSIONS AND RELEVANCE: Bitopertin-mediated glycine reuptake inhibition may represent a novel treatment option for schizophrenia, with the potential to address negative symptoms. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00616798.

Paliperidone extended-release tablets in schizophrenia patients previously treated with risperidone.

To assess the effect of paliperidone extended-release (ER) tablets in patients with acute symptoms who had previously received risperidone. Data for this post-hoc analysis were pooled from three 6-week, double-blind, placebo-controlled trials in patients treated with paliperidone ER 3-12 mg/day or placebo. Patients had to have received risperidone for > or =4 weeks within 2 weeks of study entry. Assessments were done using the Positive and Negative Syndrome Scale, Clinical Global Impressions-Severity scale, Personal and Social Performance scale, the Simpson-Angus Scale , and adverse event (AE) reports. Altogether, 198 patients (paliperidone ER, n=142; placebo, n=56) met the established criteria. Mean (SD) duration of prior risperidone treatment and dose were 418.8 (572.8) days and 4.4 (2.5) mg/day for paliperidone ER and 527.0 (805.3) days and 4.1 (2.5) mg/day for placebo. Study completion rates were 61.3% for paliperidone ER versus 42.9% for placebo. At endpoint, paliperidone ER showed significant improvement versus placebo (P<0.05) in Positive and Negative Syndrome Scale, Clinical Global Impressions-Severity, and Personal and Social Performance scores. Mean baseline Simpson-Angus Scale scores were low, with no significant changes at endpoint in either group. AEs > or =10% with paliperidone ER versus placebo were headache (16.2 vs. 16.1%), insomnia (14.1 vs. 16.1%), and agitation (8.5 vs. 10.7%). AE-related discontinuations were 2.1% with paliperidone ER and 5.4% with placebo. In patients who had received risperidone previously but remained sufficiently symptomatic for enrollment, paliperidone ER was significantly more effective than placebo in reducing symptoms and producing functional gains.