Regional brain mGlu5 receptor occupancy following single oral doses of mavoglurant as measured by [11C]-ABP688 PET imaging in healthy volunteers.

Mavoglurant binds to same allosteric site on metabotropic glutamate receptor 5 (mGluR5) as [11C]-ABP688, a radioligand. This open-label, single-center pilot study estimates extent of occupancy of mGluR5 receptors following single oral doses of mavoglurant, using [11C]-ABP688 positron emission tomography (PET) imaging, in six healthy males aged 20-40 years. This study comprised three periods and six subjects were divided into two cohorts. On Day 1 (Period 1), baseline clinical data and safety samples were obtained along with PET scan. During Period 2 (1-7 days after Period 1), cohort 1 and 2 received mavoglurant 25 mg and 100 mg, respectively. During Period 3 (7 days after Period 2), cohort 1 and 2 received mavoglurant 200 mg and 400 mg, respectively. Mavoglurant showed the highest distribution volumes in the cingulate region with lower uptake in cerebellum and white matter, possibly because myelinated axonal sheets maybe devoid of mGlu5 receptors. Maximum concentrations of mavoglurant were observed around 2-3.25 h post-dose. Mavoglurant passed the blood-brain barrier and induced dose- and exposure-dependent displacement of [11C]-ABP688 from the mGluR5 receptors, 3-4 h post-administration (27%, 59%, 74%, 85% receptor occupancy for mavoglurant 25 mg, 100 mg, 200 mg, 400 mg dose, respectively). There were no severe adverse effects or clinically significant changes in safety parameters. This is the first human receptor occupancy study completed with Mavoglurant. It served to guide the dosing of mavoglurant in the past and currently ongoing clinical studies. Furthermore, it confirms the utility of [11C]-ABP688 as a unique tool to study drug-induced occupancy of mGlu5 receptors in the living human brain.

Mavoglurant (AFQ056) for the treatment of levodopa-induced dyskinesia in patients with Parkinson's disease: a meta-analysis.

BACKGROUND: Mavoglurant (AFQ056), a selective metabotropic glutamate receptor 5 (mGluR5) inhibitor, was tested for t levodopa-induced dyskinesia (LID) in patients with Parkinson's Disease (PD). However, clinical trials showed inconsistent results regarding the efficacy of mavoglurant in treating LID in patients with Parkinson's disease (PD). METHODS: A computer literature search of PubMed, Scopus, Web of science, and Cochrane CENTRAL was conducted until March 2021. We selected relevant randomized controlled trials comparing mavoglurant to placebo. Study data were extracted and pooled as mean difference (MD) in the meta-analysis model. RESULTS: Six RCTs were included in this meta-analysis with a total of 485 patients. Mavoglurant was not significantly superior to placebo in terms of the "off-time" (MD -0.27 h, 95% CI -0.65 to 0.11), "on time" (MD 0.29 h, 95% CI -0.09 to 0.66), Lang-Fahn activities of daily living dyskinesia scale (MD -0.95, 95% CI -1.98 to 0.07), UPDRS-III (MD -0.51, 95% CI -1.66 to 0.65), or UPDRS-IV (MD -0.41, 95% CI -0.85 to 0.03). However, the pooled modified abnormal involuntary movement scale favored the mavoglurant group than the placebo group (MD -2.53, 95% CI -4.23 to -0.82). CONCLUSIONS: This meta-analysis provides level one evidence that mavoglurant is not effective in treating the LID in patients with PD.

Mavoglurant in Parkinson's patients with l-Dopa-induced dyskinesias: Two randomized phase 2 studies.

BACKGROUND: Two phase 2 randomized, double-blind studies were designed to evaluate efficacy and safety of immediate-release (study 1) and modified-release (study 2) mavoglurant formulations in PD l-dopa-induced dyskinesia. METHODS: Patients were randomized to mavoglurant 100-mg or placebo (4:3) groups (study 1) and mavoglurant 200-mg, mavoglurant 150-mg, or placebo (2:1:1) groups (study 2). Primary outcome was antidyskinetic efficacy, as measured by change from baseline to week 12 in modified Abnormal Involuntary Movement Scale total score. RESULTS: Differences in least-squares mean (standard error) change in modified Abnormal Involuntary Movement Scale total score in week 12 did not reach statistical significance in either study (study 1: mavoglurant 100 mg twice a day versus placebo, 1.7 [1.31]; study 2: mavoglurant 150 mg twice a day (-1.3 [1.16]) and 200 mg twice a day (-0.2 [1.03]) versus placebo). Adverse events incidence was higher with mavoglurant than with placebo. CONCLUSIONS: Both studies failed to meet the primary objective of demonstrating improvement of dyskinesia with mavoglurant treatment. © 2016 International Parkinson and Movement Disorder Society.

7TM X-ray structures for class C GPCRs as new drug-discovery tools. 1. mGluR5.

We illustrate, with a focus on mGluR5, how the recently published, first X-ray structures of mGluR 7TM domains, specifically those of mGluR1 and mGluR5 complexed with negative allosteric modulators (NAMs), will begin to influence ligand- (e.g., drug- or sweetener-) discovery efforts involving class C GPCRs. With an extensive docking study allowing full ligand flexibility and full side chain flexibility of all residues in the ligand-binding cavity, we have predicted and analyzed the binding modes of a variety of structurally diverse mGluR5 NAM ligands, showing how the X-ray structures serve to effectively rationalize each ligand's binding characteristics. We demonstrated that the features that are inherent in our earlier overlay model are preserved in the protein structure-based docking models. We identified structurally diverse compounds, which potentially act as mGluR NAMs, and revealed binding-site differences by performing high-throughput docking using a database of approximately six million structures of commercially available compounds and the mGluR1 and mGluR5 X-ray structures. By comparing the 7TM domains of the mGluR5 and mGluR1 X-rays structures, we identified selectivity factors within group I of the mGluRs. Similarly, using homology models that we built for mGluR2 and mGluR4, we have identified the factors leading to the selectivity between group I and groups II and III for ligands occupying the deepest portion of the mGluR5 binding cavity. Finally, we have proposed a structure-based explanation of the pharmacological switching within a set of positive allosteric modulators (PAMs) and their corresponding, very close NAM analogs.

Mavoglurant (AFQ056) in combination with increased levodopa dosages in Parkinson's disease patients.

Long-term use of levodopa (L-dopa) in patients with Parkinson's disease is associated with development of dyskinesia. This study explored whether Parkinson's disease patients with L-dopa-induced dyskinesia experience improved OFF-time from higher L-dopa doses without worsening of dyskinesias when receiving adjunctive mavoglurant. Patients with moderate-to-severe L-dopa-induced dyskinesia were randomized to receive mavoglurant or placebo. Mavoglurant (AFQ056) was up-titrated over two weeks from 25 mg twice daily (bid) to 100 mg bid (L-dopa kept stable), followed by three weeks during which the daily L-dopa dosage was increased by up to 300 mg/day. A sample size of 30 was initially planned; however, the study was terminated prematurely due to enrollment challenges. OFF-time showed greater improvements in the mavoglurant group (n = 7) compared with the placebo group (n = 7); difference at week 5 was -2.77 h (90% confidence interval -5.44, -0.09 h; p = 0.09). ON-time without troublesome dyskinesia increased more from baseline to week 5 in the mavoglurant group (4.38 h) versus the placebo group (0.63 h). Clinician-rated measures were conflicting. The Modified Abnormal Involuntary Movement Scale scores showed a slight improvement with mavoglurant compared with placebo, while the Unified Dyskinesia Rating Scale parts III and IV worsened slightly with mavoglurant compared with placebo. Due to the low patient numbers and conflicting clinician-rated outcomes data, our findings are not conclusive. However, our results suggest that mavoglurant combined with higher doses of L-dopa may be effective in treating patients with Parkinson's disease experiencing L-dopa-related motor fluctuations and dyskinesias.

Application of a Bayesian approach to physiological modelling of mavoglurant population pharmacokinetics.

Mavoglurant (MVG) is an antagonist at the metabotropic glutamate receptor-5 currently under clinical development at Novartis Pharma AG for the treatment of central nervous system diseases. The aim of this study was to develop and optimise a population whole-body physiologically-based pharmacokinetic (WBPBPK) model for MVG, to predict the impact of drug-drug interaction (DDI) and age on its pharmacokinetics. In a first step, the model was fitted to intravenous (IV) data from a clinical study in adults using a Bayesian approach. In a second step, the optimised model was used together with a mechanistic absorption model for exploratory Monte Carlo simulations. The ability of the model to predict MVG pharmacokinetics when orally co-administered with ketoconazole in adults or administered alone in 3-11 year-old children was evaluated using data from three other clinical studies. The population model provided a good description of both the median trend and variability in MVG plasma pharmacokinetics following IV administration in adults. The Bayesian approach offered a continuous flow of information from pre-clinical to clinical studies. Prediction of the DDI with ketoconazole was consistent with the results of a non-compartmental analysis of the clinical data (threefold increase in systemic exposure). Scaling of the WBPBPK model allowed reasonable extrapolation of MVG pharmacokinetics from adults to children. The model can be used to predict plasma and brain (target site) concentration-time profiles following oral administration of various immediate-release formulations of MVG alone or when co-administered with other drugs, in adults as well as in children.

Mavoglurant Augmentation in OCD Patients Resistant to Selective Serotonin Reuptake Inhibitors: A Proof-of-Concept, Randomized, Placebo-Controlled, Phase 2 Study.

INTRODUCTION: To determine if mavoglurant (modified release) as an augmentation therapy to selective serotonin reuptake inhibitors (SSRIs) could have beneficial effects reducing Yale-Brown Obsessive Compulsive Scale (Y-BOCS) total score in patients with obsessive-compulsive disorder (OCD) resistant to SSRI treatment. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled, parallel-group, phase 2 study. Patients remained on their SSRI treatment and mavoglurant or placebo was added on. Non-smoking men and women aged 18-65 years primarily diagnosed with OCD according to Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR) criteria were randomized (1:1) to mavoglurant or placebo groups. After 50 patients were randomized, an interim analysis was conducted to determine whether the study should be continued. The primary outcome measure was absolute change in Y-BOCS from baseline at week 17. Safety was assessed by recording adverse events (AEs) and serious adverse events (SAEs). RESULTS: Interim analysis led to a decision to terminate the study. In total 38 (76.0%) participants completed 17 weeks of treatment and 37 (74.0%) completed the study. There was no significant difference in least squares (LS) mean change from baseline at week 17 in Y-BOCS total score for mavoglurant compared with placebo groups [-6.9 (1.75) vs. -8.0 (1.78), respectively; LS mean difference 1.1; 95% CI -3.9, 6.2; p = 0.671]. The incidence of AEs was higher in the mavoglurant compared with the placebo group (80.8% vs. 70.8%, respectively). CONCLUSION: This study of mavoglurant in OCD was terminated because of the lack of efficacy at interim analysis. The study did not support the use of an antagonist of mGluR5 receptors for OCD treatment. TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov: NCT01813019. FUNDING: This study was sponsored by Novartis Pharma AG, Basel, Switzerland.

The selective metabotropic glutamate receptor 5 antagonist mavoglurant (AFQ056) reduces the incidence of reflux episodes in dogs and patients with moderate to severe gastroesophageal reflux disease.

BACKGROUND: Transient lower esophageal sphincter relaxations (TLESRs) induced by gastric distension are modulated by the metabotropic glutamate receptor 5 (mGluR5) that influences the vagal reflex loop. We therefore aimed to examine the effects of the selective mGluR5 antagonist mavoglurant (AFQ056) on the number of TLESRs in dogs and reflux episodes in patients with gastroesophageal reflux disease (GERD). METHODS: In a dog model, the number of meal-induced TLESRs was determined after intravenous (0.03, 0.1, 0.3, and 1 mg kg-1 ) and oral (1, 3, and 10 mg kg-1 ) doses of mavoglurant with reference to vehicle. In a multicenter, randomized, double-blind, placebo-controlled, three-period crossover study, the incidence of meal-induced reflux episodes was assessed by esophageal impedance monitoring after single, oral doses of mavoglurant (50 and 400 mg) or baclofen (40 mg) in 30 patients with moderate to severe GERD. KEY RESULTS: In dogs, mavoglurant reduced the number of TLESRs after intravenous and oral administration. In patients with GERD, the incidence of postprandial reflux episodes was significantly lower at a dose of 400 mg mavoglurant (-37.5% ; 90% confidence interval [CI]: -57.8, -17.2), whereas there was no significant difference at 50 mg of mavoglurant compared to placebo. A significantly lower incidence of reflux episodes was also noted with the active comparator baclofen (-50.3%; 90% CI: -66.2, -34.3), thereby validating this study. CONCLUSIONS AND INFERENCES: These data suggest a potential clinical benefit of mGluR5 antagonists such as mavoglurant in patients with GERD, particularly in those with persisting symptoms despite treatment with proton pump inhibitors.

mGlu5 negative allosteric modulators: a patent review (2013 - 2016).

INTRODUCTION: The pursuit of small molecule mGlu5 NAMs as treatments for a variety of psychiatric and neurodegenerative disorders has developed into a mature field. In addition to extensive preclinical studies, multiple compounds have advanced into clinical trials with the most advanced studies occurring in patients with FXS, PD-LID, and MDD. Areas covered: This review begins with an update of the clinical activity with mGlu5 NAMs, and then moves into a summary of patent applications filed since 2013. The summaries are organized into three separate sections: (1) inventions centered on improvements to existing clinical compounds; (2) new small molecules that maintain the prototypical disubstituted alkyne chemotype found in many mGlu5 NAM compounds; and (3) new small molecules that are not from a disubstituted alkyne chemotype. Expert opinion: It is a critical moment for mGlu5 NAM research as recent reports from clinical trials have included some significant disappointments that have blunted prior optimism. Still, research in this area remains active, and recent years have added several more attractive small molecules to this field. There is now an arsenal of diverse chemotypes available to continue to probe this target in the hopes that a drug may yet emerge.

Reduction of a Whole-Body Physiologically Based Pharmacokinetic Model to Stabilise the Bayesian Analysis of Clinical Data.

Whole-body physiologically based pharmacokinetic (PBPK) models are increasingly used in drug development for their ability to predict drug concentrations in clinically relevant tissues and to extrapolate across species, experimental conditions and sub-populations. A whole-body PBPK model can be fitted to clinical data using a Bayesian population approach. However, the analysis might be time consuming and numerically unstable if prior information on the model parameters is too vague given the complexity of the system. We suggest an approach where (i) a whole-body PBPK model is formally reduced using a Bayesian proper lumping method to retain the mechanistic interpretation of the system and account for parameter uncertainty, (ii) the simplified model is fitted to clinical data using Markov Chain Monte Carlo techniques and (iii) the optimised reduced PBPK model is used for extrapolation. A previously developed 16-compartment whole-body PBPK model for mavoglurant was reduced to 7 compartments while preserving plasma concentration-time profiles (median and variance) and giving emphasis to the brain (target site) and the liver (elimination site). The reduced model was numerically more stable than the whole-body model for the Bayesian analysis of mavoglurant pharmacokinetic data in healthy adult volunteers. Finally, the reduced yet mechanistic model could easily be scaled from adults to children and predict mavoglurant pharmacokinetics in children aged from 3 to 11 years with similar performance compared with the whole-body model. This study is a first example of the practicality of formal reduction of complex mechanistic models for Bayesian inference in drug development.

Mavoglurant in adolescents with fragile X syndrome: analysis of Clinical Global Impression-Improvement source data from a double-blind therapeutic study followed by an open-label, long-term extension study.

BACKGROUND: A phase II randomized, placebo-controlled, double-blind study and subsequent open-label extension study evaluated the efficacy, safety, and tolerability of mavoglurant (AFQ056), a selective metabotropic glutamate receptor subtype-5 antagonist, in treating behavioral symptoms in adolescent patients with fragile X syndrome (FXS). A novel method was applied to analyze changes in symptom domains in patients with FXS using the narratives associated with the clinician-rated Clinical Global Impression-Improvement (CGI-I) scale. METHODS: In the core study, patients were randomized to receive mavoglurant (25, 50, or 100 mg BID) or placebo over 12 weeks. In the extension, patients received 100 mg BID mavoglurant (or the highest tolerated dose) for up to 32 months. Global improvement, as a measure of treatment response, was assessed using the CGI-I scale. Investigators assigning CGI-I scores of 1 (very much improved), 2 (much improved), 6 (much worse), or 7 (very much worse) were provided a standard narrative template to collect further information about the changes observed in patients. Investigator feedback was coded and clustered into categories of improvement or worsening to identify potential areas of improvement with mavoglurant. Treatment effect in each category was characterized using the Cochran-Mantel-Haenszel test. RESULTS: A total of 134 and 103 patients had reached 2 weeks or more of core and extension study treatment, respectively, by the pre-assigned cutoff date for investigator feedback. In the core study, 34 CGI-I scores of 1 or 2 were reported in 28 patients; one patient scored 6. Analysis of the CGI-I narratives did not indicate greater treatment response in patients receiving mavoglurant compared with placebo in any specific improvement domain. There were 54 CGI-I scores of 1 or 2 in 47 patients in the extension study. The most frequently reported categories of improvement were behavior and mood (79.3 and 76.6 % in core and extension studies, respectively), engagement (75.9 and 78.7 %), and communication (69.0 and 61.7 %). CONCLUSIONS: A method was established to capture and categorize FXS symptoms using CGI-I narratives. Although this method did not show benefit of drug over placebo, narratives from investigators were mostly based on parental report and thus do not represent a completely objective alternative assessment. TRIAL REGISTRATION: The studies described are registered at ClinicalTrials.gov with clinical trial identifier numbers NCT01357239 and NCT01433354.

Implications of metabotropic glutamate receptor structures for drug discovery in neurotherapeutics.

Recent technological advances in the field of membrane protein structural biology have led to significantly improved success rates in the structure resolution of G protein-coupled receptors. Apart from gaining insight into the mechanics of receptor biology, these technical advances facilitate the application of structure-based drug discovery to G protein-coupled receptors. Structure-based drug discovery has the potential to significantly increase the efficiency and success rate of drug discovery campaigns against this important family of drug targets. Recently, structures of mGlu1 and mGlu5 transmembrane domains were reported in complex with negative allosteric modulators. Analysis of these structures reveals a fascinating insight into the historical difficulties associated with the drug discovery efforts for these receptors and provides an important novel template for structure-based drug discovery approaches to identify more diverse and better quality chemotypes.

Mavoglurant as a treatment for Parkinson's disease.

INTRODUCTION: A major unresolved issue in the Parkinson's disease (PD) treatment is the development of l-DOPA-induced dyskinesias (LIDs) as a side effect of chronic L-DOPA administration. Currently, LIDs are managed in part by reducing the L-DOPA dose or by the administration of amantadine. However, this treatment is only partially effective. A potential strategy, currently under investigation, is the coadministration of metabotropic glutamate receptor 5 (mGluR5) negative allosteric modulators (NAMs) and L-DOPA; a treatment that results in the improvement of dyskinesia symptoms and that permits reductions in l-DOPA dosage frequency. AREAS COVERED: The authors examine the role of mGluR5 in the pathophysiology of PD and the potential use of mGluR5 NAM as an adjuvant therapy together with a primary treatment with L-DOPA. Specifically, the authors look at the mavoglurant therapy and the evidence presented through preclinical and clinical trials. EXPERT OPINION: Interaction between mGluR5 NAM and L-DOPA is an area of interest in PD research as concomitant treatment results in the improvement of LID symptoms in humans, thus enhancing the patient's quality of life. However, few months ago, Novartis decided to discontinue clinical trials of mavoglurant for the treatment of LID, due to the lack of efficacy demonstrated in trials NCT01385592 and NCT01491529, although no safety concerns were involved in this decision. Nevertheless, the potential application of mGluR5 antagonists as neuroprotective agents must be considered and further studies are warranted to better investigate their potential.