Assessment of the long-term efficacy and safety of adjunctive perampanel in tonic-clonic seizures: Analysis of four open-label extension studies

Efficacy and safety of adjunctive perampanel treatment in pediatric patients with epilepsy aged 4-12 years: a real-world study

OBJECTIVE

To determine the efficacy and safety of perampanel (PER) as an adjunctive therapy in children aged 4-12 years with epilepsy.

METHODS

We performed a non-randomized, open-label, placebo-uncontrolled, real-world self-controlled study that included 216 young children (aged 4-12 years) with epilepsy who received PER as adjunctive therapy at the children's hospital affiliated with Chongqing Medical University from July 4, 2020, to September 20, 2023.

RESULTS

(1) The efficacy rates of adjunctive PER therapy at 3, 6, 9, and 12 months were 62.8%, 67.8%, 65.3%, and 61.2%, respectively. PER showed efficacy in alleviating focal seizures, generalized tonic-clonic seizures, myoclonic seizures, and absence seizures. The efficacy rates for variants of self-limited epilepsy with centrotemporal spikes (SeLECTS) and Lennox-Gastaut syndrome (LGS) were 89.5% and 66.7%, respectively. (2) Focal non-motor onset seizures with or without impaired awareness, focal to bilateral tonic-clonic seizures (FBTCS), LGS, variants of SeLECTS, the number of concomitant antiseizure medications (ASMs), a family history of epilepsy, and focal lesions on cranial magnetic resonance imaging were independent factors affecting efficacy. The order of PER addition did not affect efficacy. The retention rates at 3, 6, 9, and 12 months were 90.7%, 84.7%, 74.7%, 64.9%, respectively. (3) Adverse reactions occurred in 45 patients (45/216, 20.8%), with irritability/aggressive behavior (18/216, 8.3%) and somnolence (14/216, 6.5%) being the most common. Twelve patients (12/216, 5.6%) withdrew from the study because of adverse reactions.

CONCLUSION

In young Chinese children with epilepsy, PER is effective, safe, and well-tolerated as an adjunctive therapy, making it a viable option for use with broad-spectrum ASMs.

Long-term efficacy and safety of adjunctive perampanel in patients from the Asia-Pacific region with refractory focal-onset seizures in Study 335 open-label extension

OBJECTIVE

To evaluate the long-term efficacy, safety, and tolerability of adjunctive perampanel for the treatment of patients with refractory focal-onset seizures (FOS), with or without focal to bilateral tonic-clonic seizures (FBTCS), from the Asia-Pacific region.

METHODS

Study 335 (NCT01618695) was a randomized, double-blind, placebo-controlled, Phase III study. Patients aged ≥12 years with refractory FOS who completed the Core Study could enter an open-label extension (OLEx) Phase (6-week Conversion and ≥46-week Maintenance Period). Endpoints included median percent reduction in seizure frequency per 28 days, 50% responder and seizure-freedom rates, and treatment-emergent adverse events (TEAEs).

RESULTS

The Intent-to-Treat Analysis Set included 704 patients (529 received perampanel and 175 received placebo during the Core Study; all patients received perampanel during OLEx). The median percent reduction in seizure frequency and 50% responder rates in patients who received perampanel during the Core Study were maintained throughout the OLEx Phase (Week 64-75: 55.9% and 54.3%, respectively). Seizure freedom for ≥12 consecutive months at any time during perampanel treatment was achieved by 4.1% of patients with FOS and 14.2% of patients with FBTCS. Among patients treated with perampanel 4 mg/day (n = 83), median reduction in seizure frequency was lower in those who received concomitant enzyme-inducing anti-seizure medications (EIASMs) than those who received non-EIASMs. The most common TEAE was dizziness (n = 318; 46.8%); 141 (20.8%) patients had TEAEs that led to study/drug withdrawal.

SIGNIFICANCE

Overall, long-term seizure control was achieved with adjunctive perampanel in patients with refractory FOS, with or without FBTCS, in an Asia-Pacific population.

Efficacy and safety of perampanel monotherapy in Chinese patients with focal-onset seizures: A single-center, prospective, real-world observational study

OBJECTIVE

Efficacy and safety of perampanel monotherapy for treating focal-onset seizures (FOS) has been barely studied in China. This observational study aimed to evaluate the efficacy and safety of perampanel monotherapy in treating Chinese patients with FOS.

METHODS

This single-center, prospective, real-world observational study enrolled patients aged ≥4 years with FOS who visited the Epilepsy Out-Patient Clinic of Nanjing Brain Hospital affiliated to Nanjing Medical University from January 2020 to December 2021. All patients were treated with perampanel monotherapy. Seizure-freedom rates after 6 and 12 months of treatment were calculated. Adverse events (AEs) were recorded.

RESULTS

Seventy patients with FOS were enrolled. The mean maintenance perampanel dose was 4.64 ± 1.55 mg/day. The 6- and 12-month retention rates of perampanel monotherapy were 78.6% (55/70) and 70.0% (49/70), respectively. The 6- and 12-month seizure-freedom rates were 69.84% (44/63) and 65.08% (41/63), respectively. Patients with focal to bilateral tonic-clonic seizures had significantly higher 6-month and numerically higher 12-month seizure freedom rates than patients with focal impaired awareness seizures (P = 0.046 and P = 0.204, respectively). Twenty-six (37.1%) patients experienced treatment-emergent AEs, and the most common AE was dizziness. Four (5.7%) patients withdrew from the study due to AEs. No new safety concern was observed.

SIGNIFICANCE

This is the first prospective study on the efficacy and safety of perampanel monotherapy in treating Chinese patients with FOS, and perampanel monotherapy was effective and safe in treating Chinese patients aged ≥4 years with FOS up to 12 months. More multicenter, real-world studies with large sample sizes and longer follow-ups are needed to further evaluate the long-term efficacy and safety of perampanel monotherapy.

Efficacy and safety of perampanel as early add-on therapy in Chinese patients with focal-onset seizures: a multicenter, open-label, single-arm study

Background

No interventional study has been conducted in China to assess efficacy and safety of perampanel in treating Chinese patients with epilepsy, nor has there been any study on perampanel early add-on therapy in China. This interventional study aimed to assess efficacy and safety of perampanel as an early add-on treatment of focal-onset seizures (FOS) with or without focal-to-bilateral tonic-clonic seizures (FBTCS) in Chinese patients.

Methods

In this multicenter, open-label, single-arm, phase 4 interventional study, Chinese patients ≥ 12 years old with FOS with or without FBTCS who failed anti-seizure medication (ASM) monotherapy from 15 hospitals in China were enrolled and treated with perampanel add-on therapy (8-week titration followed by 24-week maintenance). The primary endpoint was 50% responder rate. Secondary endpoints included seizure-freedom rate and changes in seizure frequency from baseline. Treatment-emergent adverse events (TEAEs) and drug-related TEAEs were recorded.

Results

The full analysis set included 150 patients. The mean maintenance perampanel dose was 5.9 ± 1.5 mg/day and the 8-month retention rate was 72%. The 50% responder rate and seizure-freedom rate for all patients during maintenance were 67.9 and 30.5%, respectively. Patients with FBTCS had higher 50% responder rate (96.0%) and seizure-freedom rate (76.0%) during maintenance. Patients on concomitant sodium valproate had a significantly higher seizure-freedom rate than those on concomitant oxcarbazepine. Eight-six (55.1%) patients experienced treatment-related TEAEs, and the most common TEAEs were dizziness (36.5%), hypersomnia (11.5%), headache (3.9%), somnolence (3.2%), and irritability (3.2%). Withdrawal due to TEAEs occurred to 14.7% of the patients.

Conclusion

Perampanel early add-on was effective and safe in treating Chinese patients≥12 years old with FOS with or without FBTCS.Clinical trial registrationwww.chictr.org.cn, Identifier ChiCTR2000039510.

Assessment of the long-term efficacy and safety of adjunctive perampanel in adolescent patients with epilepsy: Post hoc analysis of open-label extension studies

OBJECTIVE

This post hoc analysis of four open-label extension (OLEx) studies evaluated the long-term efficacy and safety of adjunctive perampanel in adolescent patients (aged 12 to ≤17 years) with focal-onset seizures (FOS), with/without focal to bilateral tonic-clonic seizures (FBTCS), or generalized tonic-clonic seizures (GTCS).

METHODS

Patients who completed one of six double-blind, placebo-controlled studies could enter one of four OLEx studies comprising a blinded Conversion Period (6-16 weeks) followed by a Maintenance Phase (27 to ≤256 weeks; perampanel dose: ≤12 mg/day). Exposure, retention, seizure outcomes, and treatment-emergent adverse events (TEAEs) were analyzed. Efficacy outcomes were analyzed using observed case and last observation carried forward (LOCF) approaches; the latter was used to account for early dropouts.

RESULTS

The Full Analysis Set comprised 309 adolescents with FOS (FBTCS, n = 109) and 19 with GTCS, and the Safety Analysis Set comprised 311 with FOS (FBTCS, n = 110) and 19 with GTCS. Mean (standard deviation) cumulative duration of perampanel exposure (weeks) was: FOS, 77.7 (58.7); FBTCS, 88.7 (63.8); and GTCS, 97.0 (35.5). Retention rates were maintained for ≤2 years (FOS, 50.0 %; FBTCS, 57.1 %; GTCS, 41.7 %). Seizure control (median percent reduction in seizure frequency/28 days) was sustained for up to 2 years; FOS (59.4 %, n = 113), FBTCS (64.6 %, n = 53), and GTCS (86.5 %, n = 17). At Year 2, 50 % responder rates were: FOS, 58.4 % (n = 66); FBTCS, 54.7 % (n = 29); and GTCS, 82.4 % (n = 14); seizure-freedom rates were: FOS, 5.3 % (n = 6); FBTCS, 24.5 % (n = 13); and GTCS, 35.3 % (n = 6). Long-term seizure control was observed even in LOCF analyses. The incidence of TEAEs was highest during Year 1 (FOS, n = 269 [86.5 %]; FBTCS, n = 95 [86.4 %]; GTCS, n = 15 [78.9 %]), compared with Years 2-4; the most common (≥10 % of patients) were dizziness, somnolence, and nasopharyngitis. No new safety signals emerged with long-term treatment.

CONCLUSIONS

This post hoc analysis suggests that long-term (≤2 years) adjunctive perampanel (≤12 mg/day) is efficacious and generally well tolerated in adolescent patients with FOS, with or without FBTCS, or GTCS.

Impact of Antiseizure Medications on Appetite and Weight in Children

There are numerous potential factors that may affect growth in children with epilepsy, and these must be evaluated in any child with appetite and weight concerns. Antiseizure medications (ASMs) have potential adverse effects, and many may affect appetite, thus impacting normal growth and weight gain. The aim of this review is to focus on the impact of both epilepsy and ASMs on appetite and weight in children. We systematically reviewed studies using Medline assessing the impact of ASMs on appetite and weight in children. Eligible studies included randomized controlled trials and open-label studies (open-label extension and interventional) that targeted or included the pediatric population (0-18 years of age). Each study was classified using the American Academy of Neurology (AAN) Classification of Evidence for Therapeutic Studies, and the level of evidence for impact on appetite and weight in children was graded. ASMs associated with decreased appetite and/or weight loss include fenfluramine, topiramate, zonisamide, felbamate, rufinamide, stiripentol, cannabidiol, brivaracetam and ethosuximide; ASMs with minimal impact on weight and appetite in children include oxcarbazepine, eslicarbazepine, lamotrigine, levetiracetam, lacosamide, carbamazepine, vigabatrin and clobazam. The ASM most robustly associated with increased appetite and/or weight gain is valproic acid; however, both pregabalin and perampanel may also lead to modest weight gain or increased appetite in children. Certain ASMs may impact both appetite and weight, which may lead to increased morbidity of the underlying disease and impaired adherence to the treatment regimen.

Long-term efficacy and safety of perampanel as a first add-on therapy in patients with focal epilepsy: Three-year extension study

PURPOSE

We investigated the long-term efficacy and safety of perampanel as a first add-on therapy in patients with focal epilepsy.

METHODS

This retrospective study represented the 3-year extension phase of a multicenter, open-label, phase 4, prospective study of perampanel as a first add-on therapy in patients with focal epilepsy. Seizure and safety outcomes were assessed annually from the start of the extension study, and the retention rate was calculated from the start of perampanel exposure in the original study.

RESULTS

The 50% responder and seizure freedom rates were 84.8% and 58.7%, respectively, during the third year and 71.7% and 32.6%, respectively, during the entire 3-year period of the extension study. The 1-, 2-, and 3-year retention rates were 62.5%, 53.1%, and 52.1%, respectively. Efficacies were higher in patients that were aged >55 years, male, and receiving ≤4 mg of perampanel. Perampanel was generally well tolerated; 47.3% of patients experienced at least one adverse event during the 3 years of extension (46 adverse events (AEs) in 35 patients). The most common AEs were dizziness (33.8%), somnolence (5.4%), anger (4.1%), and irritability (4.1%). AEs were resolved with perampanel dose reduction or discontinuation in 10 (13.5%) and 12 (16.2%) patients, respectively.

CONCLUSION

Long-term treatment with perampanel as a first add-on therapy did not raise new safety signals in patients with focal epilepsy. Especially at low perampanel doses (≤4 mg/day), sustained improvement in seizure control was achieved, which could potentially avoid adverse drug reactions.

Perampanel as first add-on antiseizure medication: Italian consensus clinical practice statements

Background

When use of a single antiseizure medication (ASM) fails to induce seizure remission, add-on therapy is justified. Perampanel (PER) is approved in Europe as adjunctive therapy for focal, focal to bilateral tonic-clonic seizures and generalized tonic-clonic seizures. Aim of the study was to establish whether PER is suitable for first add-on use.

Methods

A Delphi methodology was adopted to assess consensus on a list of 39 statements produced by an Expert Board of 5 epileptologists. Using an iterative process, statements were finalized by a Delphi Panel of 84 Italian pediatric and adult neurologists. Each statement was rated anonymously to determine level of agreement on a 9-point Likert scale. Consensus was established as agreement by at least 80% of the panelists. The relevance of each statement was also assessed on a 3-point scale.

Results

Consensus was achieved for 37 statements. Characteristics of PER considered to justify its use as first add-on include evidence of a positive impact on quality of life based on long term retention data, efficacy, tolerability, and ease of use; no worsening of cognitive functions and sleep quality; a low potential for drug interactions; a unique mechanism of action. Potential unfavorable factors are the need for a relatively slow dose titration; the potential occurrence of behavioral adverse effects; lack of information on safety when used in pregnancy; limited access to plasma PER levels.

Conclusion

Perampanel has many features which justify its use as a first add-on. Choice of an ASM as first add-on should be tailored to individual characteristics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02450-y.

Perampanel effectiveness and tolerability in patients with epilepsy at long-term follow-up

INTRODUCTION

The main of the present study was to assess the effectiveness and tolerability of perampanel (PER) in association with 1 or 2 concomitant antiseizure medications (ASMs) in patients with epilepsy throughout a follow-up period of 24 months or longer in a real-world setting.

METHODS

This retrospective, observational, multi-center study collected data from both underage (<18 years old) and adult patients who had started PER in association with 1 or 2 ASMs. Only patients who had started PER and were followed up for at least 24 months were included. Response to treatment was analyzed at the 24-, 36-, and 48-month visits by considering the last visit undergone by patients. Subgroup analyses were performed according to age, gender, and epilepsy type and patients were categorized following PER treatment in concomitance with 1 or 2 ASMs to evaluate the factors affecting the achievement of seizure freedom (SF) at the 24-month FU.

RESULTS

Ninety-four patients were included (mean age 36.89 years; 51.1% female). At the 24-month follow-up visit, 90 (95.74%) patients were still receiving PER concomitantly with 1 or 2 ASMs. The mean PER dose was 6.02 mg/day and SF was achieved by 33 (35.1%) patients. A significantly higher SF rate was found in patients who had started PER with only 1 ASM when compared to those who had started PER with 2 concomitant ASMs. Effectiveness was maintained also in the subgroups of patients with a 36- or 48-month follow-up visit. Adult patients had a higher final daily dosage of PER than underage patients. Logistic regression found that the lowest number of previously failed ASMs was associated with a higher SF rate (p = 0.036).

CONCLUSION

Perampanel demonstrated a good effectiveness in association with 1 or 2 ASMs in both pediatric and adult patients, without having to use a high dose of the drug. The possibility to present SF was higher when PER was added early. Finally, the maintenance of effectiveness was observed also in the subgroups of patients with a follow-up of 36 and 48 months.

Long-term safety of adjunctive cenobamate in patients with uncontrolled focal seizures: Open-label extension of a randomized clinical study

Objective

This study was undertaken to examine long‐term (up to 7.8 years) retention rate, safety, and tolerability of the antiseizure medication (ASM) cenobamate as adjunctive treatment in the open‐label extension (OLE) of study YKP3089C013 (C013; ClinicalTrials.gov: NCT01397968).

Methods

Patients who completed the 12‐week, multicenter, multinational, double‐blind, randomized, placebo‐controlled C013 study, which examined adjunctive cenobamate treatment of adults with uncontrolled focal seizures, were eligible to enroll in the OLE. During the OLE, dose adjustments of cenobamate and concomitant ASMs were allowed. Safety assessments included frequency of treatment‐emergent adverse events (TEAEs) and serious TEAEs, TEAE severity, and TEAEs leading to discontinuation. Probability of patient continuation in the OLE was examined using a Kaplan–Meier analysis.

Results

One hundred forty‐nine patients entered the OLE (median duration of cenobamate treatment = 6.25 years). As of the data cutoff, 57% of patients (85/149) remained in the OLE (median treatment duration = 6.8 years, range = 6.4–7.8 years). The median modal daily cenobamate dose was 200 mg (range = 50–400 mg). The probability of treatment continuation at 1–6 years of cenobamate treatment was 73%, 67%, 63%, 61%, 60%, and 59%, respectively. Among patients who continued at 1 year (n = 107), the probability of continuing at Years 2–5 was 92%, 87%, 83%, and 82%. The most common discontinuation reasons were patient withdrawal (19.5%, 29/149), adverse event (10.1%, 15/149), and lack of efficacy (5.4%, 8/149). TEAEs leading to discontinuation in 1% or more of patients were fatigue (1.3%, 2/149), ataxia (1.3%, 2/149), and memory impairment or amnesia (1.3%, 2/149). Dizziness (32.9%, 49/149), headache (26.8%, 40/149), and somnolence (21.5%, 32/149) were the most frequently reported TEAEs and were primarily mild or moderate in severity.

Significance

Long‐term retention in the C013 OLE study demonstrated sustained safety and tolerability of adjunctive cenobamate treatment up to 7.8 years in adults with treatment‐resistant focal seizures taking one to three ASMs.

X-linked neonatal-onset epileptic encephalopathy associated with a gain-of-function variant p.R660T in GRIA3

The X-linked GRIA3 gene encodes the GLUA3 subunit of AMPA-type glutamate receptors. Pathogenic variants in this gene were previously reported in neurodevelopmental diseases, mostly in male patients but rarely in females. Here we report a de novo pathogenic missense variant in GRIA3 (c.1979G>C; p. R660T) identified in a 1-year-old female patient with severe epilepsy and global developmental delay. When exogenously expressed in human embryonic kidney (HEK) cells, GLUA3_R660T showed slower desensitization and deactivation kinetics compared to wildtype (wt) GLUA3 receptors. Substantial non-desensitized currents were observed with the mutant but not for wt GLUA3 with prolonged exposure to glutamate. When co-expressed with GLUA2, the decay kinetics were similarly slowed in GLUA2/A3_R660T with non-desensitized steady state currents. In cultured cerebellar granule neurons, miniature excitatory postsynaptic currents (mEPSCs) were significantly slower in R660T transfected cells than those expressing wt GLUA3. When overexpressed in hippocampal CA1 neurons by in utero electroporation, the evoked EPSCs and mEPSCs were slower in neurons expressing R660T mutant compared to those expressing wt GLUA3. Therefore our study provides functional evidence that a gain of function (GoF) variant in GRIA3 may cause epileptic encephalopathy and global developmental delay in a female subject by enhancing synaptic transmission.

Glutamate is the excitatory neurotransmitter in brain, abnormality of which causes excitotoxicity and diseases. Here we identified a pathogenic missense variant in GRIA3 gene in a female patient with severe epilepsy and global developmental delay. The X-linked GRIA3 gene encodes GLUA3, a subunit of glutamate receptors. Through electrophysiological analysis of the mutant GLUA3 in a cell line and mouse neurons, we found this mutant makes strengthened glutamate receptors. This study thus indicates that the variant causes epileptic encephalopathy and global developmental delay by enhancing glutamate signaling in brain.

Assessment of the long-term efficacy and safety of adjunctive perampanel in tonic-clonic seizures: Analysis of four open-label extension studies

OBJECTIVE

This post hoc analysis evaluated long-term efficacy and safety in patients with focal to bilateral tonic-clonic seizures (FBTCS) or generalized tonic-clonic seizures (GTCS) who entered open-label extension (OLEx) studies to receive long-term adjunctive perampanel.

METHODS

Patients aged 12 years and older who completed phase II or III randomized, double-blind, placebo-controlled studies could enter an OLEx study, each comprising a blinded conversion period followed by an open-label maintenance period (32-424 weeks; maximum perampanel dose = 12 mg/d). Exposure, seizure outcomes, and treatment-emergent adverse events (TEAEs) were analyzed.

RESULTS

Baseline characteristics were generally balanced between patients with FBTCS (n = 720) and GTCS (n = 138). Mean (standard deviation) cumulative duration of perampanel exposure was 102.3 (70.3) weeks (FBTCS) and 83.9 (38.4) weeks (GTCS). Retention rates were 50.0% for up to 4 years (FBTCS) and 49.2% for up to 2 years (GTCS). Across OLEx treatment durations, median reductions in seizure frequency per 28 days were 66.7% (FBTCS) and 80.6% (GTCS). Fifty percent and 75% responder and seizure-freedom rates were 59.5%, 45.3%, and 18.4%, respectively (FBTCS), and 72.5%, 51.5%, and 16.7%, respectively (GTCS). Efficacy was sustained for up to 4 years (FBTCS) and up to 3 years (GTCS), even when accounting for early dropouts. TEAE incidence was highest during Year 1 (FBTCS, 85.3%; GTCS, 86.2%); most common were dizziness and somnolence. During Year 1, serious TEAEs were reported in 81 (11.3%; FBTCS) and 10 (7.2%; GTCS) patients. TEAEs were consistent with the known safety profile of perampanel; no new safety signals were identified with long-term treatment.

SIGNIFICANCE

This post hoc analysis suggests long-term (up to 4 years) adjunctive perampanel (up to 12 mg/d) is efficacious and well tolerated in patients (aged 12 years and older) with FBTCS or GTCS.