Randomized, Double-Blind, Placebo-Controlled Trial of the mGlu2/3 Negative Allosteric Modulator Decoglurant in Partially Refractory Major Depressive Disorder.

OBJECTIVE: To assess putative antidepressant and procognitive effects of decoglurant, a selective metabotropic glutamate receptor type 2/3 (mGlu2/3) negative allosteric modulator, as adjunctive treatment to selective serotonin reuptake inhibitors and/or serotonin-norepinephrine reuptake inhibitors (SSRIs/SNRIs) in patients with partially refractory major depressive disorder (MDD), diagnosed using DSM-IV-TR criteria. METHODS: This randomized, placebo-controlled, double-blind, multicenter phase 2 trial consisted of 4 weeks' screening, 6 weeks' treatment, and 8 weeks' follow-up between September 2011 and June 2014. Individuals with Montgomery-Åsberg Depression Rating Scale (MADRS) score ≥ 25 and Clinical Global Impressions-Severity of Illness scale score ≥ 4, despite up to 2 adequate trials of an SSRI/SNRI and compliance confirmed by positive SSRI/SNRI blood levels, were randomized to decoglurant 5 mg (n = 101), 15 mg (n = 102), or 30 mg (n = 55) daily or placebo (n = 99) as adjunct to ongoing treatment with 1 SSRI/SNRI. An adaptive design was used with an interim analysis after 30 patients in each group had received 6 weeks' treatment. The primary outcome variable was change in MADRS total score from baseline to end of treatment. Primary assessments were performed by fully blinded centralized raters. RESULTS: Of 357 participants, 310 completed 6 weeks' treatment. At 6 weeks, no significant differences between any active treatment arm and placebo in reducing MADRS total score or response or remission rates were observed. Decoglurant exerted no significant effects on Cambridge Neuropsychological Test Automated Battery cognitive accuracy and cognitive speed composite scores or on secondary measures of mood and functioning. A relatively high placebo response was observed, which may have constrained the ability to detect treatment effects. No deaths occurred; few patients reported serious adverse events. CONCLUSIONS: Decoglurant was well tolerated overall but did not exert any antidepressant or procognitive effects. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01457677.

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.

Efficacy and Safety of Basimglurant as Adjunctive Therapy for Major Depression: A Randomized Clinical Trial.

IMPORTANCE: Antagonism of the postsynaptic metabotropic glutamate subtype 5 receptor is a novel approach to modulate glutamatergic function and has proven efficacy in a number of preclinical behavioral models of depression. OBJECTIVE: To evaluate the safety and efficacy of basimglurant modified-release (MR) vs placebo as adjunctive therapy to ongoing antidepressant medication therapy in patients with MDD who had inadequate response within the current episode. DESIGN, SETTING, AND PARTICIPANTS: In this phase 2b, double blind, randomized clinical trial of 333 adult patients with a DSM-IV-TR diagnosis of MDD across 59 research clinics globally, patients were assigned to 1 of 2 doses of basimglurant MR (0.5 or 1.5 mg) or placebo once daily, adjunctive to ongoing antidepressant medication therapy (selective serotonin reuptake inhibitor or serotonin and norepinephrine reuptake inhibitor). Patients were enrolled from October 5, 2011, through July 26, 2013. INTERVENTIONS: Six-week treatment with 0.5 mg of basimglurant MR, 1.5-mg basimglurant MR, or placebo once daily, adjunctive to ongoing antidepressant medication therapy. MAIN OUTCOMES AND MEASURES: The primary end point was the mean change from baseline score on the Montgomery-Åsberg Depression Rating Scale (MADRS), as rated by the clinician at week 6. Other measures included patient-rated MADRS, Quick Inventory of Depressive Symptomatology-Self-Report, Clinical Global Impression-Improvement, Patient Global Impression-Improvement, and Clinical Global Impression-Severity Scales and adverse events. RESULTS: A total of 596 patients were screened, and 333 were randomized into the study (mean [SD] age, 47 [11.2] years; 216 female [65.1%]). The primary end point (mean change in clinician-rated MADRS score from baseline to end of treatment) was not met (effect size [ES] = 0.16, P = .42; intent-to-treat [ITT] mixed-effects model for repeated measures [MMRM] analysis for comparing 1.5-mg basimglurant MR and placebo). Across secondary and exploratory end points, 1.5-mg basimglurant MR revealed larger improvements vs placebo on the patient-rated MADRS (-16.2 vs -13.3, ES = 0.28, nominal P = .04), Quick Inventory of Depressive Symptomatology-Self-Report (-7.5 vs -5.8; ES = 0.37, nominal P = .009), Clinical Global Impression-Improvement mean score, and Patient Global Impression-Improvement mean score. Improvements were also seen in the patient-rated MADRS remission rate (36.0% vs 22.0%; nominal P = .03) and response rate (50.5% vs 40.4%; nominal P = .13), A 0.5-mg dose of basimglurant MR had no benefit over placebo in any of these measures. The most common adverse event was dizziness, which was mostly transient and of mild intensity. CONCLUSIONS AND RELEVANCE: No difference was observed on the study's primary outcome measure, the clinician-rated MADRS change from baseline to end of treatment, between adjunctive basimglurant MR vs placebo. Adjunctive 1.5-mg basimglurant MR daily revealed, however, an antidepressant effect across secondary end points, particularly in patient-rated measures. These findings combined with good tolerability warrant further investigation with this compound in depressive disorders. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01437657.

Mechanism of amyloid removal in patients with Alzheimer disease treated with gantenerumab.

BACKGROUND: Gantenerumab is a fully human anti-Aß monoclonal antibody in clinical development for the treatment of Alzheimer disease (AD). OBJECTIVES: To investigate whether treatment with gantenerumab leads to a measurable reduction in the level of Aß amyloid in the brain and to elucidate the mechanism of amyloid reduction. DESIGN: A multicenter, randomized, double-blind, placebo-controlled, ascending-dose positron emission tomographic study. Additionally, ex vivo studies of human brain slices from an independent sample of patients who had AD were performed. SETTING: Three university medical centers. PATIENTS: Patients with mild-to-moderate AD. INTERVENTION: Two consecutive cohorts of patients received 2 to 7 infusions of intravenous gantenerumab (60 or 200 mg) or placebo every 4 weeks. Brain slices from patients who had AD were coincubated with gantenerumab at increasing concentrations and with human microglial cells. MAIN OUTCOME MEASURES: Percent change in the ratio of regional carbon 11-labeled Pittsburgh Compound B retention in vivo and semiquantitative assessment of gantenerumab-induced phagocytosis ex vivo. RESULTS: Sixteen patients with end-of-treatment positron emission tomographic scans were included in the analysis. The mean (95% CI) percent change from baseline difference relative to placebo (n = 4) in cortical brain amyloid level was -15.6% (95% CI, -42.7 to 11.6) for the 60-mg group (n = 6) and -35.7% (95% CI, -63.5 to -7.9) for the 200-mg group (n = 6). Two patients in the 200-mg group showed transient and focal areas of inflammation or vasogenic edema on magnetic resonance imaging scans at sites with the highest level of amyloid reduction. Gantenerumab induced phagocytosis of human amyloid in a dose-dependent manner ex vivo. CONCLUSION: Gantenerumab treatment resulted in a dose-dependent reduction in brain amyloid level, possibly through an effector cell-mediated mechanism of action.