Perampanel as precision therapy in rare genetic epilepsies

Perampanel in post-stroke epilepsy: Clinical practice data from the PERampanel as Only Concomitant antiseizure medication (PEROC) study

INTRODUCTION

Post-stroke epilepsy (PSE) is one of the most common causes of acquired epilepsy. Nevertheless, there is limited evidence regarding the clinical profile of antiseizure medications (ASMs) in PSE. This study aims to evaluate the 12-month effectiveness and tolerability of perampanel (PER) used as only add-on treatment in patients with PSE in a real-world setting.

METHODS

We performed a subgroup analysis of PSE patients included in a previous retrospective, longitudinal, multicentre observational study on adults. Treatment discontinuation, seizure frequency and adverse events were collected at 3, 6 and 12 months. Sub-analyses by early (≤1 previous ASM) or late PER add-on were also conducted.

RESULTS

Our analysis included 56 individuals with PSE, characterized by varying initial treatment modalities and timeframes relative to disease onset. We found notable retention rates (92.8%, 83.7%, and 69% at 3, 6, and 12 months), with treatment withdrawal mainly due to poor tolerability. One year after PER introduction, seizure frequency significantly reduced, with a responder rate (≥50% reduction) of 83.9% and a seizure-free rate of 51.6%. Adverse events occurred in 25 (46.3%) patients, mainly dizziness, irritability, and behavioural disorders. No major statistical differences were found between early (30 patients, 53.6%) and late add-on groups, except for a higher 6-month responder rate in the early add-on group.

CONCLUSION

Adjunctive PER was effective and well-tolerated in patients with PSE in a real-world setting. Perampanel demonstrated good efficacy and safety as both early and late add-on treatment, making it a compelling option for this unique patient population.

Allosteric competition and inhibition in AMPA receptors

Excitatory neurotransmission is principally mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype ionotropic glutamate receptors (AMPARs). Negative allosteric modulators are therapeutic candidates that inhibit AMPAR activation and can compete with positive modulators to control AMPAR function through unresolved mechanisms. Here we show that allosteric inhibition pushes AMPARs into a distinct state that prevents both activation and positive allosteric modulation. We used cryo-electron microscopy to capture AMPARs bound to glutamate, while a negative allosteric modulator, GYKI-52466, and positive allosteric modulator, cyclothiazide, compete for control of the AMPARs. GYKI-52466 binds in the ion channel collar and inhibits AMPARs by decoupling the ligand-binding domains from the ion channel. The rearrangement of the ligand-binding domains ruptures the cyclothiazide site, preventing positive modulation. Our data provide a framework for understanding allostery of AMPARs and for rational design of therapeutics targeting AMPARs in neurological diseases.

Perampanel for Treatment of People with a Range of Epilepsy Aetiologies in Clinical Practice: Evidence from the PERMIT Extension Study

INTRODUCTION

It is important to assess the effectiveness of an antiseizure medication in treating different epilepsy aetiologies to optimise individualised therapeutic approaches. Data from the PERaMpanel pooled analysIs of effecTiveness and tolerability (PERMIT) Extension study were used to assess the effectiveness and safety/tolerability of perampanel (PER) when used to treat individuals with a range of epilepsy aetiologies in clinical practice.

METHODS

A post hoc analysis was conducted of PERMIT Extension data from individuals with a known aetiology. Retention was assessed after 3, 6 and 12 months. Effectiveness was assessed after 3, 6 and 12 months and at the last visit (last observation carried forward). Effectiveness assessments included responder rate (≥ 50% seizure frequency reduction) and seizure freedom rate (no seizures since at least the prior visit). Safety/tolerability was assessed by evaluating adverse events (AEs) and AEs leading to discontinuation.

RESULTS

PERMIT Extension included 1945 individuals with structural aetiology, 1012 with genetic aetiology, 93 with an infectious aetiology, and 26 with an immune aetiology. Retention rates at 12 months were 61.1% (structural), 65.9% (genetic), 56.8% (infectious) and 56.5% (immune). At the last visit, responder rates (total seizures) were 43.3% (structural), 68.3% (genetic), 37.0% (infectious) and 20.0% (immune), and corresponding seizure freedom rates were 15.8%, 46.5%, 11.1% and 5.0%, respectively. AE incidence rates were 58.0% (structural), 46.5% (genetic), 51.1% (infectious) and 65.0% (immune), and corresponding rates of discontinuation due to AEs over 12 months were 18.9%, 16.4%, 18.5% and 21.7%, respectively. The types of AEs reported were generally consistent across aetiology subgroups, with no idiosyncratic AEs emerging.

CONCLUSION

Although PER was effective and generally well tolerated when used to treat individuals with a range of epilepsy aetiologies in clinical practice, variability in its effectiveness and tolerability across the subgroups indicates that PER may be particularly useful for individuals with specific epilepsy aetiologies.

Perampanel for the treatment of epilepsy with genetic aetiology: Real-world evidence from the PERMIT Extension study

Genetic factors contribute to the aetiology of epilepsy in >50% of cases, and information on the use of antiseizure medications in people with specific aetiologies will help guide treatment decisions. The PERMIT Extension study pooled data from two real-world studies (PERMIT and PROVE) to investigate the effectiveness and safety/tolerability of perampanel (PER) when used to treat people with focal and generalised epilepsy in everyday clinical practice. This post-hoc analysis of PERMIT Extension explored the use of PER when used to treat individuals presumed to have epilepsy with a genetic aetiology. Assessments included retention rate (evaluated at 3, 6 and 12 months), effectiveness (responder and seizure freedom rates; evaluated at 3, 6, 12 months and the last visit [last observation carried forward) and tolerability (adverse events [AEs]). Of the 6822 people with epilepsy included in PERMIT Extension, 1012 were presumed to have a genetic aetiology. The most common genetic aetiologies were idiopathic generalised epilepsy (IGE; 58.2%), tuberous sclerosis (1.1%), Dravet syndrome (0.8%) and genetic epilepsy with febrile seizures plus (GEFS+; 0.5%). Retention rates at 3, 6 and 12 months in the total genetic aetiology population were 89.3%, 79.7% and 65.9%, respectively. In the total genetic aetiology population, responder rates at 12 months and the last visit were 74.8% and 68.3%, respectively, and corresponding seizure freedom rates were 48.9% and 46.5%, respectively. For the specific aetiology subgroups, responder rates at 12 months and the last visit were, respectively: 90.4% and 84.4% (IGE), 100% and 57.1% (tuberous sclerosis), 100% and 71.4% (Dravet syndrome), and 33.3% and 20.0% (GEFS+). Corresponding seizure freedom rates were, respectively: 73.1% and 64.6% (IGE), 33.3% and 22.2% (tuberous sclerosis), 20.0% and 28.6% (Dravet syndrome), and 0% and 0% (GEFS+). The incidence of AEs was 46.5% for the total genetic aetiology population, 48.8% for IGE, 27.3% for tuberous sclerosis, 62.5% for Dravet syndrome, and 20% for GEFS+. Tolerability findings were consistent with PER's known safety profile. PER was effective and generally well tolerated when used in individuals with a presumed genetic epilepsy aetiology in clinical practice. PER was effective across a wide range of genetic aetiologies.

X-Linked Epilepsies: A Narrative Review

X-linked epilepsies are a heterogeneous group of epileptic conditions, which often overlap with X-linked intellectual disability. To date, various X-linked genes responsible for epilepsy syndromes and/or developmental and epileptic encephalopathies have been recognized. The electro-clinical phenotype is well described for some genes in which epilepsy represents the core symptom, while less phenotypic details have been reported for other recently identified genes. In this review, we comprehensively describe the main features of both X-linked epileptic syndromes thoroughly characterized to date (PCDH19-related DEE, CDKL5-related DEE, MECP2-related disorders), forms of epilepsy related to X-linked neuronal migration disorders (e.g., ARX, DCX, FLNA) and DEEs associated with recently recognized genes (e.g., SLC9A6, SLC35A2, SYN1, ARHGEF9, ATP6AP2, IQSEC2, NEXMIF, PIGA, ALG13, FGF13, GRIA3, SMC1A). It is often difficult to suspect an X-linked mode of transmission in an epilepsy syndrome. Indeed, different models of X-linked inheritance and modifying factors, including epigenetic regulation and X-chromosome inactivation in females, may further complicate genotype-phenotype correlations. The purpose of this work is to provide an extensive and updated narrative review of X-linked epilepsies. This review could support clinicians in the genetic diagnosis and treatment of patients with epilepsy featuring X-linked inheritance.

The latest advances in the pharmacological management of focal epilepsies in children: a narrative review

INTRODUCTION

Focal epilepsy constitutes the most common epilepsy in children, and medical treatment represents the first-line therapy in this condition. The main goal of medical treatment for children and adolescents with epilepsy is the achievement of seizure freedom or, in drug-resistant epilepsies, a significant seizure reduction, both minimizing antiseizure medications (ASM)-related adverse events, thus improving the patient's quality of life. However, up to 20-40% of pediatric epilepsies are refractory to drug treatments. New ASMs came to light in the pediatric landscape, improving the drug profile compared to that of the preexisting ones. Clinicians should consider several factors during the drug choice process, including patient and medication-specific characteristics.

AREAS COVERED

This narrative review aims to summarize the latest evidence on the effectiveness and tolerability of the newest ASMs administered as monotherapy or adjunctive therapy in pediatric epilepsies with focal onset seizures, providing a practical appraisal based on the existing evidence.

EXPERT OPINION

The latest ASMs have the potential to be effective in the pharmacological management of focal onset seizures in children, and treatment choice should consider several drug- and epilepsy-related factors. Future treatments should be increasingly personalized and targeted on patient-specific pathways. Future research should focus on discovering new chemical compounds and repurposing medications used for other indications.

Effectiveness and safety of mono- and add-on perampanel in pediatric patients with epilepsy: Experience from a single-center retrospective study

OBJECTIVE

To evaluate the effectiveness and safety of perampanel (PER) monotherapy (MT) or add-on therapy (AT) in Chinese children with epilepsy, as well as to evaluate the data from routine therapeutic drug monitoring (TDM) of PER for these pediatric patients.

METHODS

This retrospective and observational study was carried out on children with epilepsy (n = 340) from 2020 to 2022 at the Children's Hospital of Nanjing Medical University. Outcome measures were the responder rate (50% or greater seizure reduction), long-term efficacy, and tolerability (number and types of adverse events) in MT and AT groups. Concentrations of plasma PER obtained from these patients, if available, were analyzed too.

RESULTS

A total of 279 patients achieved at least 3 months of therapy, and 58.1% responded to PER therapy. 53 of the responders were seizure-free (32.7%). The retention rate dropped from 88.0% at 3 months to 40.6% at 12 months after treatment. Patients with MT achieved better seizure control than those with AT (P < 0.001). Intriguingly, PER exerted a very weak effect on patients who took more than 2 ASMs or were diagnosed with drug-resistant epilepsy. There were no significant differences in tolerability between the two groups. In addition, 179 patients were routinely monitored for PER, and the trough concentrations (C0 ) for these patients ranged from 30.0 to 992.0 ng/mL. However, no significant difference in C0 was observed between responders and nonresponders (333 ng/mL vs 325.5 ng/mL, P = 0.264).

SIGNIFICANCE

This study provides effectiveness and safety data on Chinese children with epilepsy treated with PER either as MT or as AT. The efficacy of patients receiving MT was much better than cases administered with more than 2 ASMs or diagnosed with drug-resistant epilepsy. In addition, no association was found between the plasma PER concentration and efficacy or safety.

PLAIN LANGUAGE SUMMARY

The study reports the effects of perampanel on seizures and adverse effects in Chinese patients with epilepsy younger than 18 years. Seizures decreased in 58.1% of patients (responders); in a third of these responders, seizures stopped. After treatment was started, 88% of patients were still on perampanel at 3 months and 40.6% at 12 months. People who were treated with perampanel only were more likely to respond than those who received perampanel and other antiseizure treatments, although perampanel was tolerated equally well in these groups. Plasma perampanel concentration did not predict seizure response or adverse effects.

Understanding the role of AMPA receptors in autism: insights from circuit and synapse dysfunction

Autism spectrum disorders represent a diverse etiological spectrum that converge on a syndrome characterized by discrepant deficits in developmental domains often highlighted by concerns in socialization, sensory integration, and autonomic functioning. Importantly, the incidence and prevalence of autism spectrum disorders have seen sharp increases since the syndrome was first described in the 1940s. The wide etiological spectrum and rising number of individuals being diagnosed with the condition lend urgency to capturing a more nuanced understanding of the pathogenic mechanisms underlying the autism spectrum disorders. The current review seeks to understand how the disruption of AMPA receptor (AMPAr)-mediated neurotransmission in the cerebro-cerebellar circuit, particularly in genetic autism related to SHANK3 or SYNGAP1 protein dysfunction function and autism associated with in utero exposure to the anti-seizure medications valproic acid and topiramate, may contribute to the disease presentation. Initially, a discussion contextualizing AMPAr signaling in the cerebro-cerebellar circuitry and microstructural circuit considerations is offered. Subsequently, a detailed review of the literature implicating mutations or deletions of SHANK3 and SYNGAP1 in disrupted AMPAr signaling reveals how bidirectional pathogenic modulation of this key circuit may contribute to autism. Finally, how pharmacological exposure may interact with this pathway, via increased risk of autism diagnosis with valproic acid and topiramate exposure and potential treatment of autism using AMPAr modulator perampanel, is discussed. Through the lens of the review, we will offer speculation on how neuromodulation may be used as a rational adjunct to therapy. Together, the present review seeks to synthesize the disparate considerations of circuit understanding, genetic etiology, and pharmacological modulation to understand the mechanistic interaction of this important and complex disorder.

Unveiling the Multifaceted Problems Associated with Dysrhythmia

Dysrhythmia is a term referring to the occurrence of spontaneous and repetitive changes in potentials with parameters deviating from those considered normal. The term refers to heart anomalies but has a broader meaning. Dysrhythmias may concern the heart, neurological system, digestive system, and sensory organs. Ion currents conducted through ion channels are a universal phenomenon. The occurrence of channel abnormalities will therefore result in disorders with clinical manifestations depending on the affected tissue, but phenomena from other tissues and organs may also manifest themselves. A similar problem concerns the implementation of pharmacotherapy, the mechanism of which is related to the impact on various ion currents. Treatment in this case may cause unfavorable effects on other tissues and organs. Drugs acting through the modulation of ion currents are characterized by relatively low tissue specificity. To assess a therapy's efficacy and safety, the risk of occurrences in other tissues with similar mechanisms of action must be considered. In the present review, the focus is shifted prominently onto a comparison of abnormal electrical activity within different tissues and organs. This review includes an overview of the types of dysrhythmias and the basic techniques of clinical examination of electrophysiological disorders. It also presents a concise overview of the available pharmacotherapy in particular diseases. In addition, the authors review the relevant ion channels and their research technique based on patch clumping.

A novel approach to seizures in neonates

THE CHALLENGE OF SEIZURE RECOGNITION

Recognition of seizures in neonates remains the foremost challenge to overcome. All neonates at risk for seizures, especially the critically ill, should undergo video-EEG monitoring. The initial step toward an accurate diagnosis is the accurate description and interpretation of the electro-clinical phenotype. THE IMPORTANCE OF SEIZURE SEMIOLOGY AND ASSOCIATION WITH ETIOLOGY: The early distinction between acute provoked seizures and neonatal-onset epilepsies serves as the primary determinant for guiding management, treatment choices, and duration. Seizures in neonates should be seen as a symptom, not a disease, and their semiology may suggest the etiology.

TREATMENT OF ACUTE PROVOKED SEIZURES

Neonates with hypoxic-ischemic encephalopathy respond best to phenobarbital, while levetiracetam is a better choice for neonates with congenital heart diseases. Anti-seizure medication can be discontinued after 72 h of seizure freedom, before discharge from the hospital.

TREATMENT OF NEONATAL EPILEPSIES

Neonates with epilepsy usually require a personalized, etiology-based approach in terms of choice and duration of treatment. Neonates with channelopathies tend to respond to sodium channel blockers such as carbamazepine, oxcarbazepine, or phenytoin. The surgical option should be considered early in cases of large brain malformations, such as hemimegalencephaly.

Efficacy of perampanel in pediatric epilepsy with known and presumed genetic etiology

OBJECTIVE

The efficacy of perampanel (PER) in pediatric epilepsy with specific etiologies has not been well established. Here, we investigated outcome and predictors of PER treatment in a pediatric cohort with known and presumed genetic etiology.

METHODS

We included pediatric patients with potential genetic epilepsy who received PER treatment and underwent whole-exome sequencing (WES) from January 2020 to September 2021. All patients were followed up for >12 months.

RESULTS

A total of 124 patients were included. Overall response rates were 51.6% and 49.6% at 6 months and 12 months, respectively. Pathogenic or likely pathogenic variants in 27 multiple genes were detected among 58 patients (46.8%) by WES. On performing multivariate logistic regression analysis, only developmental delay (OR = 0.406, P = 0.042) was a negative predictor of treatment response. However, the seizure onset age, positive WES results, and number of ASMs before PER administration were not significantly. Thirteen carriers with variants in the SCN1A gene showed a better response compared to eight patients with other sodium channels (P = 0.007), and to the other 45 patients with positive WES results (OR = 7.124, 95% CI = 1.306-38.860, P = 0.023). Adverse events were only reported in 23 patients, the most common being emotional problems.

INTERPRETATION

PER is safe and efficacious in pediatric patients with known and presumed genetic etiology. The response rate is comparable to that reported in other pediatric populations, and lower among those with developmental delay. A gene-specific response to PER is found along with better efficacy links to pathogenic variants in the SCN1A gene.

The broad-spectrum activity of perampanel: state of the art and future perspective of AMPA antagonism beyond epilepsy

Glutamate is the brain's main excitatory neurotransmitter. Glutamatergic neurons primarily compose basic neuronal networks, especially in the cortex. An imbalance of excitatory and inhibitory activities may result in epilepsy or other neurological and psychiatric conditions. Among glutamate receptors, AMPA receptors are the predominant mediator of glutamate-induced excitatory neurotransmission and dictate synaptic efficiency and plasticity by their numbers and/or properties. Therefore, they appear to be a major drug target for modulating several brain functions. Perampanel (PER) is a highly selective, noncompetitive AMPA antagonist approved in several countries worldwide for treating different types of seizures in various epileptic conditions. However, recent data show that PER can potentially address many other conditions within epilepsy and beyond. From this perspective, this review aims to examine the new preclinical and clinical studies-especially those produced from 2017 onwards-on AMPA antagonism and PER in conditions such as mesial temporal lobe epilepsy, idiopathic and genetic generalized epilepsy, brain tumor-related epilepsy, status epilepticus, rare epileptic syndromes, stroke, sleep, epilepsy-related migraine, cognitive impairment, autism, dementia, and other neurodegenerative diseases, as well as provide suggestions on future research agenda aimed at probing the possibility of treating these conditions with PER and/or other AMPA receptor antagonists.