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

Neuropsychopharmacology. 2018 Feb;43(3):503-512. doi: 10.1038/npp.2017.177. Epub 2017 Aug 17.

Abstract

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.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • DNA Methylation
  • Double-Blind Method
  • Excitatory Amino Acid Antagonists / adverse effects
  • Excitatory Amino Acid Antagonists / therapeutic use*
  • Female
  • Fragile X Mental Retardation Protein / genetics
  • Fragile X Syndrome / drug therapy*
  • Fragile X Syndrome / genetics
  • Fragile X Syndrome / metabolism
  • Fragile X Syndrome / psychology
  • Humans
  • Imidazoles / adverse effects
  • Imidazoles / therapeutic use*
  • Male
  • Middle Aged
  • Psychotropic Drugs / adverse effects
  • Psychotropic Drugs / therapeutic use*
  • Pyridines / adverse effects
  • Pyridines / therapeutic use*
  • RNA, Messenger / blood
  • Receptor, Metabotropic Glutamate 5 / antagonists & inhibitors*
  • Receptor, Metabotropic Glutamate 5 / metabolism
  • Treatment Failure
  • Young Adult

Substances

  • 2-chloro-4-(1-(4-fluorophenyl)-2,5-dimethyl-1H-imidazol-4-ylethynyl)pyridine
  • Excitatory Amino Acid Antagonists
  • FMR1 protein, human
  • GRM5 protein, human
  • Imidazoles
  • Psychotropic Drugs
  • Pyridines
  • RNA, Messenger
  • Receptor, Metabotropic Glutamate 5
  • Fragile X Mental Retardation Protein