A multivariable prediction model of a major treatment response for focal-onset seizures: A post-hoc analysis of Phase III trials of perampanel

OBJECTIVE

Although 50 % reduction in seizure frequency is a common efficacy endpoint in clinical trials of antiepileptic drugs (AEDs), 75 % or greater reductions may be required to improve patients' health-related quality of life. Identification of clinical factors that are associated with high responder rates may help to inform clinicians on which patients may optimally benefit from treatment. We evaluated potential predictive factors for achieving major treatment responses (≥75 % reduction in seizure frequency per 28 days from study baseline) in patients with drug-resistant focal-onset seizures, with/without focal to bilateral tonic-clonic (FBTC) seizures in perampanel trials designed for regulatory approval.

METHODS

Univariate analyses using logistic regression were performed using data from three double-blind, placebo-controlled Phase III studies of adjunctive perampanel (Studies 304 [NCT00699972], 305 [NCT00699582], 306 [NCT00700310]), and their open-label extension study (OLEx; Study 307 [NCT00735397]). For the double-blind studies, baseline seizure frequency, number of baseline AEDs, baseline seizure type, baseline concomitant enzyme-inducing AEDs (EIAEDs), baseline carbamazepine, lamotrigine, or valproic acid, age at diagnosis, time since diagnosis, etiology, and perampanel plasma concentration were included individually with study treatment. The same factors were included for the OLEx analysis except for plasma concentration and treatment. Variables found to be significant predictors for a major treatment response in univariate analyses were subsequently included in multivariable analyses using backwards and forwards selection.

RESULTS

In the double-blind studies, 175/1374 patients had a major response to placebo (n = 25) or perampanel (n = 150). The best predictors of a major treatment response in multivariable models with forwards and backwards selection were: the presence of FBTC seizures during baseline (P = 0.0002), higher perampanel plasma concentration (P < 0.0001), older age at diagnosis (P = 0.0024 and 0.0045, respectively), and lower baseline seizure frequency (P = 0.0364 and 0.0127, respectively). In the OLEx, 217/1090 patients had a major treatment response. The best predictors of a major treatment response in the final multivariable model, regardless of backwards or forwards selection, were a lower baseline seizure frequency (P = 0.0022), the absence of focal impaired awareness seizures during baseline (P = 0.0011), the presence of FBTC seizures during baseline (P = 0.0164), lower number(s) of baseline AEDs (P = 0.0002), the absence of EIAEDs during baseline (P = 0.0059), an older age at diagnosis (P = 0.0054), and absence of structural etiologies (P = 0.0138).

SIGNIFICANCE

These analyses of placebo-controlled and long-term extension trial data identified a number of potential predictive factors for patients with focal-onset seizures achieving a major treatment response. These factors may help guide clinicians when predicting a patient's response to treatment and optimizing individual treatment regimens.

In Vitro Metabolism of Slowly Cleared G Protein-Coupled Receptor 139 Agonist TAK-041 Using Rat, Dog, Monkey, and Human Hepatocyte Models (HepatoPac): Correlation with In Vivo Metabolism

Hepatic metabolism of low-clearance compound TAK-041 was studied in two different in vitro model systems using rat, dog, monkey, and human suspended cryopreserved hepatocytes and HepatoPac micropatterned coculture model primary hepatocytes. The aim of this work was to investigate the most appropriate system to assess the biotransformation of TAK-041, determine any notable species difference in the rate and in the extent of its metabolic pathways, and establish correlation with in vivo metabolism. TAK-041 exhibited very low turnover in suspended cryopreserved hepatocyte suspensions for all species, with no metabolites observed in human hepatocytes. However, incubations conducted for up to 14 days in the HepatoPac model resulted in more robust metabolic turnover. The major biotransformation pathways of TAK-041 proceed via hydroxylation on the benzene ring fused to the oxotriazine moiety and subsequent sulfate, glucuronide, and glutathione conjugation reactions. The glutathione conjugate of TAK-041 undergoes further downstream metabolism to produce the cysteine S-conjugate, which then undergoes N-acetylation to mercapturic acid and/or conversion to β-lyase-derived thiol metabolites. The minor biotransformation pathways include novel ring closure and hydrolysis, hydroxylation, oxidative N-dealkylation, and subsequent reduction. The HepatoPac model shows a notable species difference in the rate and in the extent of metabolic pathways of TAK-041, with dogs having the fastest metabolic clearance and humans the slowest. Furthermore, the model shows its suitability for establishing correlation with in vivo metabolism of low-turnover and extensively metabolized compounds such as TAK-041, displaying an extensive and unusual downstream sequential β-lyase-derived thiol metabolism in preclinical species and human. SIGNIFICANCE STATEMENT: This study investigated the most appropriate in vitro system to assess the biotransformation of the low-turnover and extensively metabolized compound TAK-041, determine any notable species difference in the rate and in the extent of its metabolic pathways, and establish correlation with in vivo metabolism. The HepatoPac model was identified and showed its suitability for species comparison and establishing correlation, with in vivo metabolism displaying an extensive and unusual downstream sequential β-lyase-derived thiol metabolism in preclinical species and human.

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.

Meta-analysis of drug efficacy in adult vs pediatric trials of patients with PGTC seizures

Objective

A meta-analysis of published studies was performed to determine whether the efficacy of antiseizure drugs in adults with primary generalized tonic-clonic seizures (PGTCS) is comparable with that in the pediatric population (2–12 years of age).

Methods

Electronic searches were conducted in EMBASE, Medline, and the Cochrane Central Register of Controlled Trials for clinical trials of PGTCS in adults and children 2–12 years of age. Neurologists used standardized search and study evaluations to select eligible trials. Median percent reduction in seizure frequency from baseline and ≥50% responder rates were used to compare drug efficacy in adults and children.

Results

Among 7 adjunctive-therapy PGTCS trials in adults and children (2–12 years of age) that met evaluation criteria, effect sizes were consistent between adults and children for lamotrigine and topiramate. The baseline-subtracted median percent seizure reduction in seizure frequency ranged from 50.0% to 79.7% in children and 57.0% to 64.0% in adults. The ≥50% responder rate was similar between children and adults in a topiramate study (50% in children compared with 58% in adults).

Conclusions

This meta-analysis supports the use of drug response from antiseizure drug clinical trials for PGTCS in adults to predict comparable treatment response in children 2–12 years of age with PGTCS.

Open-label study to investigate the safety and efficacy of adjunctive perampanel in pediatric patients (4 to <12 years) with inadequately controlled focal seizures or generalized tonic-clonic seizures

Objective

Study 311 (NCT02849626) was a global, multicenter, open‐label, single‐arm study that assessed safety, tolerability, pharmacokinetics, and pharmacokinetics/pharmacodynamics of once‐daily adjunctive perampanel oral suspension in pediatric patients (aged 4 to <12 years) with focal seizures (FS) (with/without focal to bilateral tonic‐clonic seizures [FBTCS]) or generalized tonic‐clonic seizures (GTCS).

Methods

In the 311 Core Study, a 4‐week Pre‐treatment Period (Screening/Baseline) preceded a 23‐week Treatment Period (11‐week Titration; 12‐week Maintenance) and 4‐week Follow‐up. Endpoints included safety/tolerability (primary endpoint), median percent change in seizure frequency per 28 days from Baseline (Treatment Period), and 50% responder and seizure‐freedom rates (Maintenance Period). Patients were stratified by age (4 to <7; 7 to <12 years) and concomitant enzyme‐inducing anti‐seizure drug (EIASD) use.

Results

One hundred eighty patients were enrolled (FS, n = 149; FBTCS, n = 54; GTCS, n = 31). The Core Study was completed by 146 patients (81%); the most common primary reason for discontinuation was adverse event (AE) (n = 14 [8%]). Mean (standard deviation) daily perampanel dose was 7.0 (2.6) mg/day and median (interquartile range) duration of exposure was 22.9 (2.0) weeks. The overall incidence of treatment‐emergent AEs (TEAEs; 89%) was similar between patients with FS (with/without FBTCS) and GTCS. The most common TEAEs were somnolence (26%) and nasopharyngitis (19%). There were no clinically important changes observed for cognitive function, laboratory, or electrocardiogram (ECG) parameters or vital signs. Median percent reductions in seizure frequency per 28 days from Baseline were as follows: 40% (FS), 59% (FBTCS), and 69% (GTCS). Corresponding 50% responder and seizure‐freedom rates were as follows: FS, 47% and 12%; FBTCS, 65% and 19%; and GTCS, 64% and 55%, respectively. Improvements in response/seizure frequency from Baseline were seen regardless of age or concomitant EIASD use.

Significance

Results from the 311 Core Study suggest that daily oral doses of adjunctive perampanel are generally safe, well tolerated, and efficacious in children age 4 to <12 years with FS (with/without FBTCS) or GTCS.

Adjunctive Perampanel Oral Suspension in Pediatric Patients From ≥2 to <12 Years of Age With Epilepsy: Pharmacokinetics, Safety, Tolerability, and Efficacy

Study 232, an open-label pilot study with an extension phase, evaluated the pharmacokinetics and preliminary safety/tolerability and efficacy of adjunctive perampanel oral suspension (≤0.18 mg/kg/d) in epilepsy patients aged ≥2 to <12 years. Patients were grouped into cohorts 1 (aged ≥7 to <12 years) and 2 (aged ≥2 to <7 years). The Core Study included pretreatment (≤2 weeks) and treatment phases (7-week titration; 4-week maintenance; 4-week follow-up [for those not entering the extension]). The extension phase consisted of 41-week maintenance and 4-week follow-up periods. Pharmacokinetic data were pooled with adolescent pharmacokinetic data from phase II/III studies. Population pharmacokinetic analysis showed that perampanel pharmacokinetics was independent of age, weight, or liver function, suggesting age- or weight-based dosing is not required and that the same dose can be given to adults and children to achieve exposures shown to be efficacious. Perampanel was well tolerated and efficacious for ≤52 weeks.

056 Perampanel and secondarily generalised seizures in a pooled analysis of phase III studies and their open-label extension: effect of enzyme-inducing antiepileptic drugs

Introduction

Perampanel is approved for adjunctive treatment of partial seizures, with or without secondarily generalised seizures (SGS), and primary generalised tonic-clonic seizures in epilepsy patients aged ≥12 years. Approval of perampanel for partial seizures was based on three randomised, double-blind, placebo-controlled, Phase III Studies 304 (NCT00699972), 305 (NCT00699582) and 306 (NCT00700310); patients completing these could enter open-label extension (OLEx) Study 307 (NCT00735397). Here, we report efficacy of perampanel as adjunctive treatment of SGS by co-administration of enzyme-inducing antiepileptic drugs (EIAEDs) versus non-EIAEDs in both the Phase III and OLEx studies.

Methods

In the double-blind studies, patients (≥12 years) with partial seizures, with or without SGS, receiving 1–3 AEDs at Baseline were randomised to placebo or 2–12 mg/day perampanel for 19 weeks. In the OLEx, patients received ≤12 mg/day perampanel for ≤272 weeks. Efficacy assessments included median percent change in SGS frequency/28 days, SGS 50% and 75% responder and seizure-freedom rates.

Results

For patients with SGS at pre-perampanel Baseline, 564 were in the double-blind studies and 388 received perampanel for ≥1 year in the OLEx. In the double-blind studies, perampanel co-administered with an EIAED (carbamazepine, eslicarbazepine, oxcarbazepine, phenytoin) had reduced efficacy compared with non-EIAEDs due to increased clearance; this was particularly evident at higher doses, although these differences were still greater than placebo. In the OLEx, concomitant administration of both non-EIAEDs and EIAEDs was associated with sustained efficacy, with slightly better efficacy during the first, second and third years of perampanel exposure for non-EIAEDs compared with EIAEDs.

Conclusion

Perampanel demonstrated good and sustained long-term efficacy against SGS. With the recent FDA approval of perampanel for monotherapy use for partial seizures, non-EIAED data may be more relevant for consideration if perampanel is used as a single agent (no other AED) while real-world data and experience are accumulated.

Study support

Eisai Inc.

Long-term effects of adjunctive perampanel on cognition in adolescents with partial seizures

OBJECTIVE

The aim of this study was to evaluate long-term effects of adjunctive perampanel on cognition, efficacy, growth, safety, and tolerability in adolescents with inadequately controlled partial seizures.

METHODS

Study 235, a multicenter, randomized, double-blind, placebo-controlled, parallel-group, Phase II study with an open-label extension phase (NCT01161524), was primarily designed to assess the effects of adjunctive perampanel on cognition. Patients (aged ≥12 to <18years) had a diagnosis of epilepsy with inadequately controlled partial seizures, with or without secondary generalization, despite receiving 1-3 antiepileptic drugs. During the double-blind phase, adjunctive perampanel or placebo was administered over a 6-week titration period and a 13-week maintenance period up to 12mg/day. During the extension phase, all patients received perampanel. Data from the extension phase are presented here. Study endpoints included change from baseline in Cognitive Drug Research (CDR) measures of cognition, seizure frequency, growth, development, the occurrence of treatment-emergent adverse events (TEAEs), and laboratory values.

RESULTS

A total of 114 patients entered the extension phase (prior double-blind treatment: placebo, n=41; perampanel, n=73). Perampanel had no effect on the CDR system global cognition score, continuity of attention, quality of episodic memory, quality of working memory, or speed of memory but was associated with a significant decline in power of attention at end of treatment compared with baseline (p=0.03). There were no effects on language skills or manual dexterity from baseline to end of treatment. At Weeks 40-52, median reduction in seizure frequency was 74.1%, and 50% responder rate was 66.0%. There were no clinically relevant effects of perampanel on growth or development at end of treatment compared with baseline. Overall, 84.2% of patients experienced at least one TEAE and 70.2% experienced at least one treatment-related TEAE. The most common TEAEs were dizziness (29.8%) and somnolence (19.3%). The TEAEs resulted in the discontinuation of treatment in 6.1% of patients.

CONCLUSIONS

In keeping with the 19-week double-blind phase, long-term adjunctive treatment with perampanel did not have any significant overall effects on the CDR system global cognition score in adolescent patients with inadequately controlled partial seizures. Similar trends were observed across the individual CDR system domains. Adjunctive perampanel showed sustained long-term seizure control and had a safety and tolerability profile similar to that observed in prior clinical studies.

055 Effect of common concomitant antiepileptic drugs during adjunctive treatment with perampanel: post hoc analysis from the open-label extension of a phase III study in patients with idiopathic generalised epilepsy

Introduction

Perampanel is approved for adjunctive treatment of partial seizures, with or without secondarily generalised seizures, and primary generalised tonic-clonic (PGTC) seizures in epilepsy patients aged ≥12 years. Perampanel is also approved for monotherapy use for partial seizures in the US. This post hoc analysis assessed the effects of the most common concomitant Baseline antiepileptic drugs (AEDs) on discontinuation rates and treatment-emergent adverse event (TEAE) incidence during adjunctive treatment with perampanel in patients (aged ≥12 years) with idiopathic generalised epilepsy (IGE) and PGTC seizures in the open-label extension (OLEx) Phase of Study 332 (NCT02307578).

Methods

Patients completing the double-blind study could receive perampanel (≤12 mg/day) during the OLEx (6 week blinded Conversion Period;≤136 weeks’ Maintenance). Here, we report results for perampanel >4–8 mg/day and >8–12 mg/day.

Results

Most common concomitant Baseline AEDs were valproic acid (n=55), lamotrigine (n=53), levetiracetam (n=37), topiramate (n=21) and zonisamide (n=12); patients may have received >1 of these Baseline AEDs. The most common reasons for discontinuing were adverse event(s) (AE), ‘other’ and patient choice. Lamotrigine: patient choice, n=6/34 (>4–8 mg/day); AE/‘other’, both n=3/19 (>8–12 mg/day). Levetiracetam: patient choice, n=5/27 (>4–8 mg/day); AE, n=2/10 (>8–12 mg/day). Topiramate: ‘other’, n=3/15 (>4–8 mg/day); AE/‘other’, both n=1/6 (>8–12 mg/day). Valproic acid: patient choice, n=6/38 (>4–8 mg/day); ‘other’, n=4/17 (>8–12 mg/day). Zonisamide: patient choice/‘other’, both n=2/10 (>4–8 mg/day); no discontinuations (>8–12 mg/day). Patient-reported TEAEs ranged from: 88.2% (lamotrigine) to 93.3% (topiramate) for perampanel >4–8 mg/day, and 70.6% (valproic acid) to 100.0% (topiramate and zonisamide) for perampanel >8–12 mg/day. The most common TEAE was dizziness.

Conclusion

In this post hoc analysis, primary reasons for discontinuation and TEAE incidence differed between the most common Baseline AED subgroups and perampanel dose range, although TEAE types were similar. These data provide additional information on the safety of adjunctive perampanel in patients with IGE.

Study support

Eisai Inc.

Pharmacokinetic/pharmacodynamic analysis of adjunctive perampanel in subjects with partial-onset seizures

OBJECTIVES

Explore perampanel pharmacokinetics (PK) in all subjects (aged ≥12 years) vs adolescents (aged ≥12 to ≤17 years) with partial-onset seizures (POS) and identify factors explaining between-subject variability in efficacy using a population PK/pharmacodynamic (PD) analysis.

MATERIALS & METHODS

Population PK analysis was performed using nonlinear mixed-effect modeling with data from phase II/III randomized, double-blind, placebo-controlled studies of adjunctive perampanel in POS. Perampanel exposure was predicted for all subjects and adolescents. Population PK/PD analyses were performed using data from phase III studies to explore the relationship between perampanel exposure and 28-day average seizure frequency and responder probability.

RESULTS

Pooled perampanel PK data from 1318 subjects were described by a one-compartment disposition model. In the absence of antiepileptic drugs (AEDs) affecting perampanel PK, estimated perampanel apparent clearance (CL/F) was 0.668 L/h (all subjects) and 0.682 L/h (adolescent subjects). Co-administration of carbamazepine and oxcarbazepine/phenytoin reduced perampanel exposure. Gender, Asian race (excluding Japanese or Chinese), and increasing alanine aminotransferase lowered perampanel CL/F, but differences were small and not considered clinically relevant. Adolescent outcomes were similar to the total population. Based on PK/PD data from 1748 subjects, percent reduction in 28-day average seizure frequency from baseline and responder probability increased with increasing perampanel exposure; concomitant CYP3A-inducing AEDs lowered perampanel exposure but did not impact the slope for responder probability.

CONCLUSIONS

These results are consistent with previous analyses but expand on these through inclusion of a larger number of patients from different ethnic groups, and demonstrate that outcomes were similar between adults and adolescents.

Evaluation of perampanel as monotherapy for focal seizures: Experience from open-label extension studies

Perampanel, a selective, non-competitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, is approved for adjunctive treatment of focal seizures, with or without secondarily generalized seizures, and for primary generalized tonic–clonic seizures in patients with epilepsy aged ≥ 12 years. Perampanel was recently approved for monotherapy use for focal seizures in the U.S.A. Anti-seizure drug monotherapy may be preferable to polytherapy, which is generally associated with increased toxicity, non-compliance, and cost. Here, we report cases where patients had converted to perampanel monotherapy during open-label extension (OLEx) portions of 9 Phase II and III studies.

Of 2245 patients who enrolled in the OLEx studies, we identified 7 patients with drug-resistant focal seizures who discontinued all non-perampanel anti-seizure drugs and were maintained on perampanel monotherapy for ≥ 91 days until the end of data cut-off. Patients received perampanel monotherapy for up to 1099 days (157 weeks), most at a modal dose of 12 mg. Seizure data were available for 6 patients, of whom 5 had a ≥ 90% reduction in overall seizure frequency between baseline and their last 13-week period of monotherapy (3 were seizure-free). Perampanel monotherapy was generally well tolerated and the safety profile during perampanel monotherapy was consistent with clinical and post-marketing experience in the adjunctive setting.

This analysis included a small proportion of patients with highly drug-resistant focal seizures who converted to monotherapy during OLEx studies. While these limited data are encouraging in suggesting that perampanel might be useful as a monotherapy, further studies are required to explore outcomes in a less drug-resistant population, where a larger proportion of patients might benefit from monotherapy.

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Seven patients with drug-resistant focal seizures

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Patients on adjunctive perampanel converted to perampanel monotherapy

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Seizure frequency was markedly reduced.

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Perampanel monotherapy was generally well tolerated.

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These limited data suggest that perampanel might be useful as a monotherapy.

A retrospective, multicentre study of perampanel given as monotherapy in routine clinical care in people with epilepsy

PURPOSE

Perampanel is approved for adjunctive treatment of focal seizures, with or without secondarily generalised seizures, and for primary generalised tonic-clonic seizures in people with epilepsy aged ≥12 years. Perampanel was recently approved for monotherapy use for partial seizures in the United States. This study provides insight into the feasibility of perampanel monotherapy in real-world settings.

METHODS

This retrospective, non-interventional, multicentre study (NCT02736162) was conducted between January 2013 and March 2016 in specialist epilepsy centres in Europe and Russia. Eligible individuals had a diagnosis of epilepsy and received perampanel primary or secondary monotherapy as routine clinical care. The primary endpoint was proportion of individuals remaining on perampanel monotherapy, after conversion from perampanel adjunctive treatment, at 3, 6, 12, 18 and 24 months (retention rate).

RESULTS

Sixty individuals were in the safety set (female, 63%; white, 97%; aged 18 to <65 years, 73%). Most (85%) received secondary monotherapy with perampanel. At study cut-off, 68% of individuals were continuing on perampanel monotherapy (secondary monotherapy: 55%). The median duration of retention was not calculable due to the high number of individuals ongoing on monotherapy. Twelve individuals had treatment-emergent adverse events that started during perampanel monotherapy, the most frequent was dizziness (5%). One serious treatment-emergent adverse event was reported (pneumonia during adjunctive perampanel treatment).

CONCLUSIONS

In this small retrospective study of individuals who received perampanel monotherapy, the majority maintained monotherapy. Perampanel monotherapy may be an achievable option in some people with epilepsy.

Perampanel with concomitant levetiracetam and topiramate: Post hoc analysis of adverse events related to hostility and aggression

In 4 Phase III registration trials (3 in patients with partial seizures, N=1480; 1 in patients with PGTCS, N=163), perampanel administered to patients already receiving 1-3 concomitant antiepileptic drugs (AEDs) demonstrated statistically superior efficacy compared to placebo in reducing seizure frequency. However, use of perampanel in these studies was associated with a risk of psychiatric and behavioral adverse reactions, including aggression, hostility, irritability, anger, and homicidal ideation and threats. The present study is a post hoc analysis of pooled data from these 4 trials to determine if concomitant treatment with levetiracetam and/or topiramate increased the risk of hostility- and aggression-related AEs. Treatment-emergent AEs (TEAEs) were determined using a "Narrow & Broad" search based on the Medical Dictionary for Regulatory Activities (MedDRA) standard MedDRA query (SMQ) for hostility- and aggression-related events. The rate of hostility- and aggression-related TEAEs was observed to be similar among perampanel-treated patients: a) receiving levetiracetam (N=340) compared to those not receiving levetiracetam (N=779); b) receiving topiramate (N=223) compared to those not receiving topiramate (N=896); and c) receiving both levetiracetam and topiramate (N=47) compared to those not receiving levetiracetam and topiramate (N=1072). Severe and serious TEAEs related to hostility and aggression were rare and occurred at a similar rate regardless of concomitant levetiracetam and/or topiramate therapy. Taken together, these results suggest that concomitant treatment with levetiracetam and/or topiramate has no appreciable effect on the occurrence of hostility- or aggression-related TEAEs in patients receiving perampanel.

Effect of enzyme inhibition on perampanel pharmacokinetics: Why study design matters

OBJECTIVES

Perampanel, a selective, noncompetitive AMPA receptor antagonist, is indicated as adjunctive therapy for the treatment of partial seizures with or without secondarily generalized seizures and primary generalized tonic-clonic seizures in patients with epilepsy aged 12years and older. In vitro studies and Phase I trials indicate that perampanel is metabolized almost exclusively by CYP3A, with an elimination half-life (t_1/2) averaging approximately 105h. Understanding of pharmacokinetic (PK) interactions-enzyme inhibition or induction-and anticipating their occurrence are important for management of patients with epilepsy. Here we report PK results from a Phase I drug-drug interaction (DDI) study (Study 005) combining perampanel with the CYP3A inhibitor ketoconazole, as well as supplementary in silico predictions further exploring this interaction.

METHODS

A Phase I, randomized, open-label, two-period, two-treatment, two-way crossover study was conducted in 26 healthy adult male volunteers. Subjects were randomized to 1 of 2 treatment sequences. In one period, subjects received a single 1-mg fasting dose of perampanel (Day1); in the other period, subjects received ketoconazole 400mg once daily for 10days with a single 1-mg perampanel dose while fasting (Day3). Blood samples were drawn at multiple time points up to 288h after the perampanel dose. Pharmacokinetic parameters of perampanel were calculated by noncompartmental analysis, and safety was recorded. An integrated, physiologically based PK model built in Simcyp^® provided additional insight into this interaction. Drug-drug interaction intensity was measured by the ratio of systemic exposure (area under plasma concentration-time curve [AUC]) of perampanel in the presence or absence of concomitant ketoconazole.

RESULTS

Single oral doses of 1mg perampanel and once-daily oral doses of ketoconazole 400mg were safe and well tolerated. Maximum perampanel plasma concentration (C_max) and time to C_max showed no apparent differences when perampanel was administered alone versus with ketoconazole. Ketoconazole co-administration resulted in an approximate 20% increase in perampanel AUC (P<0.001). This increase, although statistically significant, was a<2.0-fold AUC change and alone would suggest a modest effect of ketoconazole. To further explore these results, DDI simulations were performed to query the findings and test additional study conditions. Using the actual trial conditions of Study 005, the simulations also predicted an AUC ratio increase <2-fold, providing verification of the simulation assumptions and the modest effect of ketoconazole for 10days. Simulations further suggested that an interaction effect of ketoconazole on perampanel exposure (>2-fold) of potential clinical significance could be predicted when using larger doses of ketoconazole (e.g., 200mg every 6h) coadministered for a greater time period (e.g., 30days), with AUC ratio as high as 3.36. Additionally, simulations suggested that a significant interaction with co-administration of perampanel and an inhibitor more potent than ketoconazole (such as itraconazole) could not be ruled out.

CONCLUSIONS

Selecting an appropriate study design is critical to fully characterize the PK interaction for drugs such as perampanel that have a long t_1/2. Although a negligible effect on perampanel PK was observed following co-administration of ketoconazole 400mg/day for 10days, this is likely due in part to the relatively brief co-administration period of ketoconazole and perampanel (<3 times the t_1/2 of perampanel). While short-term administration of a CYP3A inhibitor may not significantly increase perampanel exposure, such increases may be expected following chronic and larger dosing or with a more potent inhibitor.

Impact of perampanel on pharmacokinetics of concomitant antiepileptics in patients with partial-onset seizures: pooled analysis of clinical trials

Aims

To evaluate the impact of perampanel and demographics on clearance of concomitant antiepileptic drugs (AEDs), in patients with refractory partial‐onset seizures.

Methods

Pooled data from three Phase III clinical studies with adjunctive perampanel were used. Blood samples for evaluation of 11 concomitant AEDs were taken during baseline (before perampanel initiation), and at weeks 10, 14, and 19 during the maintenance phase of perampanel treatment (2–12 mg/day, once daily at bedtime). Models estimating apparent clearance of each concomitant AED were fitted to the data, and the effects of perampanel and demographic variables on clearance were determined. Final models were assessed with goodness of fit plots including population predictions and individual predictions against observations.

Results

No significant impact of perampanel on clearance was found for clonazepam (n = 81), levetiracetam (n = 330), phenobarbital (n = 54), phenytoin (n = 90), topiramate (n = 226) or zonisamide (n = 93). Statistically significant, but small and not clinically relevant increases in model‐predicted clearance were detected for carbamazepine (+4.3% with 12 mg perampanel; n = 379), clobazam (+3.4% males, +7.7% females, 12 mg; n = 114), lamotrigine (+9.3%, 12 mg; n = 356), and valproic acid (+5.0%, 12 mg; n = 349). Oxcarbazepine clearance was reduced (26%; n = 200), but the clinical relevance is unclear as levels of the active metabolite (the monohydroxy derivative of oxcarbazepine) were not measured.

Conclusions

Population PK data show that perampanel (2–12 mg/day, once daily at bedtime) has no relevant impact on the clearance of the most commonly used concomitant AEDs.

Cognitive effects of adjunctive perampanel for partial-onset seizures: A randomized trial

Objective

Assess cognitive effects of adjunctive perampanel in adolescents.

Methods

In this double‐blind study (ClinicalTrials.gov identifier: NCT01161524), patients aged 12 to <18 years with partial‐onset seizures despite receiving 1–3 antiepileptic drugs were randomized (2:1) to perampanel or placebo. Perampanel was increased weekly in 2‐mg increments to 8–12 mg/day (6‐week titration; 13‐week maintenance). Changes in neuropsychological outcomes were assessed at end of maintenance: Cognitive Drug Research (CDR) System Global Cognition Score (primary end point), five CDR System domain T‐scores (secondary end points), letter fluency, category fluency, and Lafayette Grooved Pegboard Test (LGPT).

Results

One hundred thirty‐three patients were randomized. In the full analysis set, there were no differences of perampanel (n = 79) vs. placebo (n = 44) in CDR System Global Cognition Score (least squares mean change, −0.6 vs. 1.6; p = 0.145), Quality of Working Memory (1.1 vs. 2.0; p = 0.579), or Power of Attention (−6.9 vs. −2.7; p = 0.219). There were small differences with perampanel vs. placebo in other CDR System domains: improvements in Quality of Episodic Memory (3.0 vs. −1.2; p = 0.012), and worsening in Continuity of Attention (−3.3 vs. 1.6; p = 0.013) and Speed of Memory (0.3 vs. 7.0; p = 0.032). Letter fluency, category fluency, and LGPT were not significantly different between groups. The most frequent adverse events with perampanel were dizziness (30.6%) and somnolence (15.3%).

Significance

Perampanel did not differ from placebo in the global cognitive score, two of five subdomains, and four other cognitive measures. Perampanel was worse on two and better on one subdomain.

ADJUNCTIVE PERAMPANEL RCT FOR PGTC SEIZURES

We assessed efficacy and safety of perampanel (selective noncompetitive AMPA receptor antagonist) for primary generalised tonic-clonic (PGTC) seizures. Patients ≥12years with confirmed IGE; ≥3 PGTC seizures/8 weeks prior to randomization; receiving 1–3 concomitant AEDs were recruited. Trial consisted of 4–week screening; 4–8 week Baseline, 1:1 Randomization (perampanel titrated over 4 weeks to 8mg or highest tolerated dose versus placebo), 13–week Maintenance, 4–week Follow-up and Extension Phases. 164 patients were randomized; full analysis set included 81 patients each on perampanel and placebo. Median percent change in PGTC seizure frequency/28 days during Titration/Maintenance versus Baseline was –76.5% with perampanel versus –38.4% placebo; P<0.0001. 50% PGTC seizure responder rate was 64.2% with perampanel versus 39.5% placebo; P=0.0019. During Maintenance, 30.9% of perampanel patients were free of PGTC seizures versus 12.3% placebo. Treatment-emergent AEs (TEAEs) occurred in 82.7% of perampanel and 72.0% placebo patients; most common dizziness, fatigue, headache, somnolence, irritability. Serious TEAEs occurred in 6 (7.4%) perampanel and 7 (8.5%) placebo patients (one death in the perampanel group [accidental drowning; not treatment-related],one with placebo). In conclusion, adjunctive perampanel treatment up to 8mg improved seizure control in PGTC seizure patients, with almost 1/3 free of PGTC seizures during Maintenance. Perampanel was well tolerated. Study sponsor: Eisai Inc.

Perampanel for tonic-clonic seizures in idiopathic generalized epilepsy A randomized trial

OBJECTIVE

To assess efficacy and safety of adjunctive perampanel in patients with drug-resistant, primary generalized tonic-clonic (PGTC) seizures in idiopathic generalized epilepsy (IGE).

METHODS

In this multicenter, double-blind study (ClinicalTrials.gov identifier: NCT01393743; funded by Eisai Inc.), patients 12 years or older with PGTC seizures and IGE were randomized to placebo or perampanel during a 4-week titration period (perampanel up titrated from 2 to 8 mg/d, or highest tolerated dose) and 13-week maintenance period. The primary endpoint was percent change in PGTC seizure frequency per 28 days (titration plus maintenance vs baseline). The key secondary endpoint (primary endpoint for European Union registration) was 50% PGTC seizure responder rate (patients achieving $50% reduction in PGTC seizure frequency; maintenance vs baseline). Treatment-emergent adverse events were monitored.

RESULTS

Of 164 randomized patients, 162 comprised the full analysis set (placebo, 81; perampanel, 81). Compared with placebo, perampanel conferred a greater median percent change in PGTC seizure frequency per 28 days (238.4%vs 276.5%; p , 0.0001) and greater 50%PGTC seizure responder rate (39.5% vs 64.2%; p 5 0.0019). During maintenance, 12.3% of placebo treated patients and 30.9%of perampanel-treated patients achieved PGTC seizure freedom. For the safety analysis (placebo, 82; perampanel, 81), the most frequent treatment-emergent adverse events with perampanel were dizziness (32.1%) and fatigue (14.8%).

CONCLUSIONS

Adjunctive perampanel was well tolerated and improved control of drug-resistant PGTC seizures in patients with IGE.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that adjunctive perampanel reduces PGTC seizure frequency, compared with placebo, in patients with drug-resistant PGTC seizures in IGE.

Analysis of pooled phase III trials of adjunctive perampanel for epilepsy: Impact of mechanism of action and pharmacokinetics on clinical outcomes

AIM

To further explore the impact of concomitant antiepileptic drugs (AEDs) on the efficacy and tolerability of adjunctive perampanel for focal epilepsy.

METHODS

Data were pooled from three phase III trials of adjunctive perampanel in patients (≥12 years of age) with refractory partial-onset seizures. Concomitant AEDs were categorized according to whether or not they were enzyme-inducing AEDs (EIAEDs; known to reduce perampanel plasma concentrations) or sodium channel blockers (SCBs). Post hoc analyses assessed the impact of co-administration of non-EIAED SCBs and the overall number of concomitant AEDs on changes in seizure frequency, 50% responder rates, rates of treatment-emergent adverse events (TEAEs), and rates of discontinuation due to TEAEs, in patients randomized to receive daily placebo or perampanel 2, 4, 8, or 12mg.

RESULTS

Amongst 1480 randomized and treated patients, most were receiving two or more concomitant AEDs (n=1273, 86.0%), one or more EIAEDs (n=1083, 73.2%), and/or one or more SCBs (n=1203, 81.3%) at Baseline. The magnitude of seizure reduction appeared unaffected by the presence of non-EIAED SCBs, but lower in the presence of multiple AEDs. Frequency of TEAEs did not appear to be affected by the presence of non-EIAED SCBs or multiple AEDs.

CONCLUSION

Beyond the known interactions between perampanel and EIAEDs, perampanel efficacy appears to be unaffected by the use of concomitant non-EIAED SCBs, but may be reduced in the presence of multiple concomitant AEDs (possibly indicative of the presence of more refractory epilepsy). Nonetheless, with careful titration to balance efficacy and tolerability, perampanel may be combined with a range of AEDs, facilitating integration into treatment plans.

Psychiatric and behavioral adverse events in randomized clinical studies of the noncompetitive AMPA receptor antagonist perampanel

Objective

Perampanel, a selective, noncompetitive α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) glutamate receptor antagonist, is indicated for adjunctive treatment of partial seizures in patients ≥12 years based on three phase III clinical studies. The perampanel U.S. Prescribing Information includes a boxed warning for serious psychiatric and behavioral adverse reactions. To provide context for this warning, detail on psychiatric and behavioral safety data from perampanel clinical studies is presented.

Methods

An analysis of pooled safety data from three phase III studies in patients with partial seizures is presented. Data from phase I and phase II studies in patients with and without epilepsy were also analyzed. Psychiatric and behavioral treatment‐emergent adverse events (TEAEs) were evaluated according to Medical Dictionary for Regulatory Activities (MedDRA) terms, using “narrow” and “narrow‐and‐broad” standardized MedDRA queries (SMQs) for TEAEs suggestive of hostility/aggression.

Results

From the three phase III partial‐seizure studies, the overall rate of psychiatric TEAEs was higher in the 8 mg (17.2%) and 12 mg (22.4%) perampanel groups versus placebo (12.4%). In the “narrow” SMQ, hostility/aggression TEAEs were observed in 2.8% for 8 mg and 6.3% for 12 mg perampanel groups, versus 0.7% of placebo patients. “Narrow‐and‐broad” SMQs for hostility/aggression TEAE rates were 12.3% for 8 mg and 20.4% for 12 mg perampanel groups, versus 5.7% for placebo; rates for events resulting in discontinuation were perampanel = 1.6% versus placebo = 0.7%. For events reported as serious AEs (SAEs), rates were perampanel = 0.7% versus placebo = 0.2%. In nonepilepsy patients, psychiatric TEAEs were similar between patients receiving perampanel and placebo. In phase I subjects/volunteers, all psychiatric TEAEs were mild or moderate. These analyses suggest that psychiatric adverse effects are associated with use of perampanel.

Significance

Patients and caregivers should be counseled regarding the potential risk of psychiatric and behavioral events with perampanel in patients with partial seizures; patients should be monitored for these events during treatment, especially during titration and at higher doses.

Efficacy and safety of perampanel in adolescent patients with drug-resistant partial seizures in three double-blind, placebo-controlled, phase III randomized clinical studies and a combined extension study

OBJECTIVE

Assess perampanel's efficacy and safety as adjunctive therapy in adolescents (ages 12-17) with drug-resistant partial seizures.

METHODS

Adolescent patients enrolled in multinational, double-blind, placebo-controlled, phase III core studies (studies 304, 305, or 306) completed 19-week, double-blind phase (6-week titration/13-week maintenance) with once-daily perampanel or placebo. Upon completion, patients were eligible for the extension (study 307), beginning with 16-week, blinded conversion, during which placebo patients switched to perampanel. Patients then entered the open-label treatment.

RESULTS

Of 1480 patients from the core studies, 143 were adolescents. Pooled adolescent data from these core studies demonstrated median percent decreases in seizure frequency for perampanel 8 mg (34.8%) and 12 mg (35.6%) were approximately twice that of placebo (18.0%). Responder rates increased with perampanel 8 mg (40.9%) and 12 mg (45.0%) versus placebo (22.2%). Adolescents receiving concomitant enzyme-inducing antiepileptic drugs (AEDs) had smaller reductions in seizure frequency (8 mg:31.6%; 12 mg:26.8%) than those taking non-inducing AEDs (8 mg:54.6%; 12 mg:52.7%). Relative to pre-perampanel baseline, seizure frequency and responder rates during the extension (Weeks 1-52) improved with perampanel. Most commonly reported adverse events in adolescents during the core studies were dizziness (20.4%), somnolence (15.3%), aggression (8.2%), decreased appetite (6.1%), and rhinitis (5.1%). Dizziness (13.2%), somnolence (11.6%), and aggression (6.6%) most often led to perampanel interruption/dose adjustment during the extension.

SIGNIFICANCE

Data demonstrated adjunctive perampanel treatment in adolescents with drug-resistant partial seizures produced better seizure control versus placebo, sustained seizure frequency improvements, and a generally favorable safety profile. Results were comparable to the overall study population.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov Identifiers: Study 304: NCT00699972; 305: NCT00699582; 306: NCT00700310; Study 307: NCT00735397.

Perampanel in the treatment of partial seizures: Time to onset and duration of most common adverse events from pooled Phase III and extension studies

Perampanel (PER) is a novel noncompetitive AMPA-receptor antagonist approved in over 40 countries for treatment of partial seizures. The safety and tolerability of PER have been well-documented in three double-blind, randomized, placebo (PBO)-controlled Phase III studies and an open-label extension (OLE). This post hoc analysis evaluated the occurrence and characteristics of the most common treatment-emergent adverse events (TEAEs) associated with PER. Results from the Phase III studies were pooled; post hoc analyses on the double-blind phase and up to 1 year of the OLE were performed on the four most common TEAEs for which incidence was higher for PER than PBO. The four most common TEAEs were dizziness, somnolence, fatigue, and irritability. For most subjects in the Phase III double-blind studies, these TEAEs were observed during 6-week titration and were mild or moderate in severity. For severe AEs, no dose-response relationship was observed. Patients in the PBO group during Phase III (who therefore received their first PER treatment during OLE) experienced these TEAEs with incidence and timing similar to that of PER-treated patients in Phase III. The first onset of these TEAEs occurred during the early weeks of PER conversion in the OLE. After 6months and up to 1 year of PER treatment, low to no incidence of the first onset of the four TEAEs was observed. Post hoc analyses of data from pooled Phase III studies provide greater insight into occurrence/duration of TEAEs. Phase III double-blind and OLE data showed that dizziness, somnolence, fatigue, and irritability were the most common TEAEs reported by patients taking PER. Additionally, these results suggest consistency between studies in patient responses to onset of these TEAEs. Although concomitant antiepileptic drugs (AEDs) might be predicted to affect development of TEAEs in patients taking PER, an effect was not observed in this analysis. The low incidence of TEAEs in these studies provides additional support for long-term PER treatment.

Perampanel efficacy and safety by gender: Subanalysis of phase III randomized clinical studies in subjects with partial seizures

The antiepileptic drug (AED) perampanel is approved in ≥40 countries as adjunctive therapy for drug‐resistant partial seizures in patients with epilepsy. This post hoc analysis of pooled data from three phase III, double‐blind, randomized studies of perampanel examines between‐gender differences in perampanel efficacy and safety. Of the 1,478 subjects in the pooled analysis (719 male, 759 female), 1,109 were included in the pharmacokinetic/pharmacodynamic analysis. Perampanel oral clearance was 17% lower in female than in male patients not receiving enzyme‐inducing AEDs. Pooled efficacy analysis revealed that seizure frequency was reduced with perampanel treatment regardless of gender; a greater numerical reduction in seizure frequency and increased responder rates occurred in female participants at perampanel doses of 4, 8, and 12 mg. Tolerability was similar between groups, although common adverse events such as dizziness and headache occurred more frequently in female subjects. Modest elevations in perampanel exposure in female patients may result in meaningful between‐gender differences in efficacy and safety; therefore, dosing should be individualized and clinical response monitored.

Lack of effect of perampanel on QT interval duration: Results from a thorough QT analysis and pooled partial seizure Phase III clinical trials

INTRODUCTION

Perampanel is a selective, noncompetitive AMPA receptor antagonist approved as adjunctive treatment for partial seizures. To assess potential for delayed cardiac repolarization, a Phase I thorough QT study was performed, supplemented by plasma concentration-QT data modeled from 3 pooled Phase III studies.

METHODS

The Phase I thorough QT study (double-blind, combined fixed-sequence, parallel-group) quantified the effect of perampanel (6 mg once daily for 7 days, followed by dose escalation to a single 8-mg dose, a single 10-mg dose, then 12 mg once daily for 7 days), moxifloxacin positive control (single 400-mg dose on Day 16), and placebo on QT interval duration in healthy subjects (N = 261). Electrocardiograms were recorded at baseline, Day 7 (post 6 mg dose), and Day 16 (post 12 mg dose). Statistical comparisons were between the highest approved perampanel dose (12 mg) versus placebo, a "mid-therapeutic" dose (6 mg) versus placebo, and moxifloxacin versus placebo. Acknowledging that the Phase I thorough QT study could not incorporate a true "supratherapeutic" dose due to length of titration and tolerability concerns in healthy subjects, Phase III studies of perampanel included expanded electrocardiogram safety evaluations specifically intended to support concentration-QT response modeling. The lack of effect of perampanel on the QT interval is shown from pooled analysis of 3 double-blind, placebo-controlled, 19-week, Phase III studies with perampanel doses ≤ 12 mg (N = 1038, total perampanel; and N=442, placebo) in patients with partial seizures. QT measures were corrected for heart rate using Fridericia's (QTcF; the primary endpoint) and Bazett's (QTcB) formulas.

RESULTS

In the Phase I thorough QT study, the positive control moxifloxacin caused peak time-matched, baseline-adjusted, placebo-corrected (ΔΔ) QTcF of 12.15 ms at 4h postdose, confirming a drug effect on QTc interval and study assessment sensitivity. Mean baseline-adjusted (Δ) QTcF versus nominal time curves were comparable between perampanel 12 mg and placebo, with most ΔQTcF values being slightly negative. Healthy subjects receiving perampanel 6 and 12 mg doses for 7 days showed no evidence of effects on cardiac repolarization. Peak ΔΔQTcF was 2.34 ms at 1.5h postdose for perampanel 6 mg and 3.92 ms at 0.5h postdose for perampanel 12 mg. At every time point, the upper 95% confidence limit of ΔΔQTcF for perampanel 6 and 12 mg was <10 ms. Phase III studies revealed no clinically significant difference between patients with partial seizures treated with perampanel or placebo in QTcF and QTcB values >450 ms, with no dose-dependent increases or large incremental changes from baseline of >60 ms. Regression analysis of individual plasma perampanel concentrations versus corresponding QTc interval values in Phase I thorough QT and Phase III studies demonstrated no relationship between perampanel concentrations and QT interval duration.

CONCLUSION

Treatment with perampanel 6 mg and 12 mg for 7 days did not delay cardiac repolarization in healthy volunteers. In a population analysis of 1480 patients with partial seizures treated with perampanel doses ≤ 12 mg or placebo, no clinically significant trends in QT interval data were noted. Based on the thorough QT study and evaluations from pooled Phase III studies, there is no evidence of prolonged QT interval duration with perampanel treatment.

Perampanel efficacy and tolerability with enzyme-inducing AEDs in patients with epilepsy

OBJECTIVE

Evaluate the impact of concomitant enzyme (CYP3A4)-inducer antiepileptic drugs (EIAEDs) on the efficacy and safety of perampanel in patients from the 3 phase-III clinical trials.

METHODS

Patients with pharmacoresistant partial-onset seizures in the 3 phase-III clinical studies were aged 12 years and older and receiving 1 to 3 concomitant antiepileptic drugs. Following 6-week baseline, patients were randomized to once-daily, double-blind treatment with placebo or perampanel 8 or 12 mg (studies 304 and 305) or placebo or perampanel 2, 4, or 8 mg (study 306).

RESULTS

Treatment response assessed by median percent reduction in seizure frequency and responder rates improved with perampanel compared with placebo. However, at 8 and 12 mg, the treatment response was significantly greater in patients receiving non-EIAEDs. The treatment effect (perampanel-placebo) also demonstrated a dose-dependent increase in all patients. The overall incidence of treatment-emergent adverse events was similar regardless of the presence of EIAEDs. Occurrence of some adverse events, such as fatigue, somnolence, dizziness, irritability, was greater in patients receiving non-EIAEDs, as was discontinuation because of adverse events.

CONCLUSIONS

Perampanel shows efficacy and safety in the presence and absence of EIAEDs. As systemic exposure to perampanel increases, so does efficacy. Given the extensive metabolism of perampanel, systemic exposure is clearly reduced with concomitant administration of CYP3A4 inducers. This supports the strategy of dosing perampanel to clinical effect. Recognition of these pharmacokinetic interactions will be important in the optimization of this novel medication.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that 2 to 12 mg/d doses of perampanel reduced seizure frequency and improved responder rate in the presence and absence of EIAEDs.

Efficacy and safety of perampanel in the subgroup of elderly patients included in the phase III epilepsy clinical trials

Clinical data regarding use of antiepileptic drugs in the elderly are generally scarce. Therefore, a subanalysis of subjects aged ≥ 65 years who participated in the 3 phase III perampanel studies was undertaken to determine efficacy and safety in these patients. Efficacy (change in seizure frequency/28 days and 50% responder rate) in the elderly subgroup was found to be consistent with the adult population. Adverse event rates were also largely similar, with some exceptions. Because risks of falls, dizziness, and fatigue were greater in the elderly, careful titration of perampanel in patients aged ≥ 65 years is suggested, especially at higher doses, where balancing tolerability and clinical response is necessary.

The practical impact of altered dosing on perampanel plasma concentrations: pharmacokinetic modeling from clinical studies

RATIONALE

Perampanel is a selective AMPA receptor antagonist approved for adjunctive therapy in patients with refractory partial-onset seizures. Perampanel is metabolized primarily via CYP3A4, yet it has a relatively long half-life of 105h; it is, therefore, recommended that perampanel be given once daily (preferably at bedtime). Many patients occasionally have less-than-perfect adherence to their drug regimen, and given the known pharmacokinetic interactions of perampanel with commonly used enzyme-inducing antiepileptic drugs (EIAEDs), we explored the effects of a missed dose on steady-state perampanel plasma concentrations and the ramifications of "make up" doses in these patients. Although perampanel is approved for once-daily dosing, some clinicians may elect to give perampanel as a divided dose (i.e., twice daily), so we also sought to examine the pharmacokinetic impact of twice- versus once-daily dosing.

METHODS

Pharmacokinetic simulations were performed using validated perampanel pharmacokinetic parameters, derived from 19 phase I studies in 606 subjects, to investigate the effect on perampanel plasma concentration of (1) missing a dose of perampanel followed by delayed replacement of the missed dose, (2) missing a dose followed by resumption of scheduled therapy, and (3) missing a dose in the presence/absence of carbamazepine. Simulations were done for a typical patient receiving an 8-mg once-daily or a 4-mg twice-daily dose using the nonlinear mixed effects program, NONMEM v7.2, in conjunction with PDx-pop v5.

RESULTS

Our results corroborate that given the pharmacokinetic characteristics of perampanel, a missed dose is unlikely to cause as much fluctuation in plasma concentration as would be expected for a drug with a short half-life. Importantly, simulations suggest that supplementing a missed dose 6-12h later, followed by continuation of the regular schedule, may not result in any significant "spikes" in perampanel plasma concentrations. Simulations demonstrated that twice-daily dosing offered little advantage in further flattening the concentration-time profile of perampanel in the adherent patient. However, fluctuations in plasma concentrations are minimized by twice-daily dosing in patients receiving concomitant EIAEDs.

CONCLUSIONS

These pharmacokinetic simulations suggest that the long half-life of perampanel may be advantageous in conferring a relatively smooth concentration-time profile with a once-daily or twice-daily dosing, even in the presence of concomitant EIAEDs. However, the results of the present study suggest that perampanel replacement is recommended for patients taking an EIAED to mitigate the potential risks associated with reduced exposure. Confirmation of the ultimate clinical impact of these findings will require further study.

Perampanel for adjunctive treatment of partial-onset seizures: a pooled dose-response analysis of phase III studies

OBJECTIVE

To better understand the relationship between efficacy and perampanel dose, integrated actual (last) dose data from three phase III trials and an extension study (blinded Conversion Period; open-label Maintenance Period) were analyzed.

METHODS

Seizure frequency data were analyzed in patients who were randomized to and completed the 13-week Maintenance Period of the phase III studies on perampanel 8 mg, and who received an actual (last) dose of 12 mg during (1) the extension 16-week blinded Conversion Period or (2) weeks 1-13 of the extension Maintenance Period. Due to a treatment-by-region interaction (p = 0.042), analyses excluded patients from the Latin America region (n = 162/1,480; 10.9% of the treated cohort).

RESULTS

Of 372 patients randomized to 8 mg in the phase III studies, 273 completed the Maintenance Period at 8 mg and 267 entered the extension study. In patients who then had an actual (last) dose of 12 mg during the extension blinded Conversion Period (n = 217), median percent change in seizure frequency per 28 days improved from -32.4% (8 mg, phase III Maintenance Period) to -44.2% (12 mg, extension blinded Conversion Period); 50% responder rates increased slightly from 37.3% to 42.9%. In patients who completed the phase III studies on 8 mg and had an actual (last) dose of 12 mg during weeks 1-13 of the extension Maintenance Period (n = 181), median percent change in seizure frequency per 28 days improved from -34.1% (phase III Maintenance Period) to -46.0% (weeks 1-13 extension Maintenance Period); 50% responder rates were 39.2% and 46.4%. Seizure control remained substantially unchanged in patients who completed the phase III studies at 12 mg and continued on that dose during the extension.

SIGNIFICANCE

Increasing perampanel dose from 8 to 12 mg can produce additional benefits in seizure control in at least some patients who tolerate the higher dose.

Development of perampanel in epilepsy

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors play a key role in mediating glutamatergic transmission in the cortex. Perampanel (2-[2-oxo-1-phenyl-5-pyridin-2-yl-1,2-dihydropyridin-3-yl] benzonitrile) is a potent, orally active, highly selective, non-competitive AMPA-type glutamate receptor antagonist, identified via a focused discovery program at Eisai Research Laboratories. Development of perampanel as adjunctive therapy for the treatment of partial-onset seizures was planned in keeping with regulatory guidance and guidelines on antiepileptic drug (AED) development. This is the first AED with a specific action on glutamate-mediated excitatory neurotransmission to show evidence of efficacy and tolerability in reducing treatment-refractory partial-onset seizures in Phase III clinical trials. Perampanel (Fycompa(®)) has been approved in the EU and the United States for adjunctive treatment of partial-onset seizures.

Perampanel, a selective, noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist, as adjunctive therapy for refractory partial-onset seizures: interim results from phase III, extension study 307

PURPOSE

To evaluate safety, tolerability, and seizure outcome data during long-term treatment with once-daily adjunctive perampanel (up to 12 mg/day) in patients with refractory partial-onset seizures.

METHODS

Study 307 was an extension study for patients completing the double-blind phase of three pivotal phase III trials (studies 304, 305, and 306). The study consisted of two phases: an open-label treatment phase (including a 16-week blinded conversion period and a planned 256-week maintenance period) and a 4-week follow-up phase. Patients were blindly titrated during the conversion period to their individual maximum tolerated dose (maximum 12 mg/day). Adverse events (AEs) were monitored throughout the study and seizure frequency recorded. The interim data cutoff date for analyses was December 1, 2010.

KEY FINDINGS

In total, 1,218 patients were enrolled in the study. At the interim cutoff date, 1,186 patients were in the safety analysis set; 1,089 (91.8%) patients had >16 weeks of exposure to perampanel, 580 (48.9%) patients had >1 year of exposure, and 19 (1.6%) patients had >2 years of exposure. At the interim analysis, 840 (70.8%) patients remained on perampanel treatment. The large majority of patients (n = 1,084 [91%]) were titrated to 10 mg or 12 mg/day. Median (range) duration of exposure was 51.4 (1.1-128.1) weeks. Treatment-emergent AEs were reported in 87.4% of patients. The most frequent were dizziness (43.9%), somnolence (20.2%), headache (16.7%), and fatigue (12.1%). Serious AEs were reported in 13.2% of patients. In the intent-to-treat analysis set (n = 1,207), the frequency of all seizures decreased over the first 26 weeks of perampanel treatment in patients with at least 26 weeks of exposure to perampanel (n = 1,006 [83.3%]); this reduction was maintained in patients with at least 1 year of exposure (n = 588 [48.7%]). The overall median percent changes in seizure frequency in patients included in each 13-week interval of perampanel treatment were -39.2% for weeks 14-26 (n = 1,114), -46.5% for weeks 40-52 (n = 731), and -58.1% for weeks 92-104 (n = 59). Overall responder rates in patients included in each 13-week interval of perampanel treatment were 41.4% for weeks 14-26 (n = 1,114), 46.9% for weeks 40-52 (n = 731), and 62.7% for weeks 92-104 (n = 59). During the blinded conversion period, the reduction in seizure frequency in patients previously randomized to placebo (-42.4%, n = 369) was similar to that in patients previously randomized to perampanel (-41.5%, n = 817).

SIGNIFICANCE

Consistent with pivotal phase III trials, these interim results demonstrated that perampanel had a favorable tolerability profile in patients with refractory partial-onset seizures over the longer term. The decrease in seizure frequency was consistent and maintained in those patients over at least 1 year of perampanel exposure.

Adjunctive perampanel for refractory partial-onset seizures: randomized phase III study 304

OBJECTIVE

To assess efficacy and safety of once-daily 8 or 12 mg perampanel, a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist, when added to concomitant antiepileptic drugs (AEDs) in the treatment of drug-resistant partial-onset seizures.

METHODS

This was a multicenter, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT00699972). Patients (≥12 years, with ongoing seizures despite 1-3 AEDs) were randomized (1:1:1) to once-daily perampanel 8 mg, 12 mg, or placebo. Following baseline (6 weeks), patients entered a 19-week double-blind phase: 6-week titration (2 mg/week increments to target dose) followed by a 13-week maintenance period. Percent change in seizure frequency was the primary endpoint; 50% responder rate was the primary endpoint for EU registration.

RESULTS

Of 388 patients randomized and treated, 387 provided seizure frequency data. Using this intent-to-treat population over the double-blind phase, the median percent change in seizure frequency was -21.0%, -26.3%, and -34.5% for placebo and perampanel 8 and 12 mg, respectively (p = 0.0261 and p = 0.0158 for 8 and 12 mg vs placebo, respectively). Fifty percent responder rates during the maintenance period were 26.4%, 37.6%, and 36.1%, respectively, for placebo, perampanel 8 mg, and perampanel 12 mg; these differences were not statistically significant for 8 mg (p = 0.0760) or 12 mg (p = 0.0914). Sixty-eight (17.5%) patients discontinued, including 40 (10.3%) for adverse events. Most frequent treatment-emergent adverse events were dizziness, somnolence, irritability, headache, fall, and ataxia.

CONCLUSIONS

This trial demonstrated that once-daily, adjunctive perampanel at doses of 8 or 12 mg improved seizure control in patients with uncontrolled partial-onset seizures. Doses of perampanel 8 and 12 mg were safe, and tolerability was acceptable.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that once-daily 8 and 12 mg doses of adjunctive perampanel are effective in patients with uncontrolled partial-onset seizures.

GW320659 for the treatment of attention-deficit/hyperactivity disorder in children

OBJECTIVE

To assess the safety, tolerability, and efficacy of GW320659, a chemically novel inhibitor of norepinephrine and dopamine reuptake, in pediatric attention-deficit/hyperactivity disorder (ADHD).

METHOD

This was a multicenter, open-label, dose-titration study of seven daily dose levels of GW320659: 1.25, 2.5, 5, 7.5,10,12.5, and 15 mg. Treatment began with the lowest dose of GW320659 and increased weekly until subjects (mean age 9.1 years) achieved a maximum acceptable dose. Subjects remained at their maximum acceptable dose for a 4-week treatment period. The key efficacy end-point was clinical response (Clinical Global Impressions of Improvement score of 1 or 2 and an improvement of 5 or more points on at least one of the Conners Parent or Teacher Rating Scales Tscore). Other end-points included assessments of safety and of quality of life using the Child Health Questionnaire Parent Form 28 (CHQ-PF28).

RESULTS

Fifty-one subjects entered the titration phase and 46 subjects completed the study. During the treatment phase, these 46 subjects received a mean dose of 14.2 mg/day and the maximum exposure to GW320659 was 11 weeks. At the end of the treatment period, 76% of subjects showed improvement with GW320659 and there were significant improvements in 7 of the 12 subscales of the CHQ-PF28 compared with baseline (p < .05). Adverse events were generally mild; only five subjects required downward titration because of adverse events (three psychiatric, one neurological and urological, one cardiovascular), and no subject withdrew because of adverse events.

CONCLUSIONS

GW320659 may have clinically relevant efficacy in pediatric ADHD and was well tolerated in this short-term initial study in children.