Long-term tolerability, safety and efficacy of adjunctive perampanel in the open-label, dose-ascending Study 231 and extension Study 233 in Japanese patients with epilepsy

Perampanel as only add-on epilepsy treatment in elderly: A subgroup analysis of real-world data from retrospective, multicenter, observational study

INTRODUCTION

Drug management of epilepsy in the elderly presents unique but data on this population are scarce. This study aimed to assess the effectiveness and tolerability of perampanel (PER) used as only add-on to a background anti-seizure medication (ASM) in the elderly in a real-world setting.

METHODS

We performed a subgroup analysis of patients aged ≥65 years included in a previous 12-month multicenter study on adults. Treatment discontinuation, seizure frequency, and adverse events were recorded at 3, 6 and 12 months after PER introduction. Sub-analyses by early (≤1 previous ASM) or late PER add-on were also conducted.

RESULTS

The sample included 65 subjects (mean age: 75.7 ± 7.2 years), with mainly focal (73.8%) epilepsy. The mean PER daily dose was ≈4 mg during all follow-up. Retention rates at 3, 6, and 12 months were 90.5%, 89.6%, and 79.4%ly. The baseline median normalized per 28-day seizure number significantly decreased at 3-, 6- and 12-month visits. One year after PER introduction, the responder rate (≥50% reduction in baseline seizure frequency) was 89.7%, with a seizure freedom rate of 72.4%. Adverse events occurred in 22 (34.9%) patients with dizziness and irritability being the most frequent. No major differences between early (41 patients, 63.1%), and late add-on groups were observed.

CONCLUSION

Adjunctive PER was effective and well-tolerated when used as only add-on treatment in elderly people with epilepsy in clinical practice, thus representing a suitable therapeutic option in this age category.

Efficacy and tolerability of perampanel in patients with seizures in real-world clinical practice: A systematic review and meta-analysis

Objectives: The aim of this study was to systematically review the efficacy and tolerability of perampanel (PER) when used as add-on treatment or monotherapy in patients with epilepsy aged 12 years and older in routine clinical practice.

Methods: Electronic and clinical trials databases were searched for observational studies of PER published up to 1 March 2022. The outcomes of interest were responder rates, adverse effects (AEs), and withdrawal rates. Subgroup analyses were performed to explore the potential factors that might affect the efficacy and safety of PER usage.

Results: A total of 56 studies, which included 10,688 patients, were enrolled. The results showed that after 3, 6, and 12 months of PER treatment, the pooled 50% responder rates in patients with epilepsy were 50.0% (95% CI: 0.41–0.60), 44.0% (95% CI: 0.38–0.50), and 39.0% (95% CI: 0.31–0.48), respectively, and the pooled seizure-free rates were 24.0% (95% CI: 0.17–0.32), 21.0% (95% CI: 0.17–0.25), and 20.0% (95% CI: 0.16–0.24), respectively. Subgroup analyses revealed that the efficacy of PER could be affected by the way in which PER is administrated. Patients in the groups where PER was used as the first add-on, primary monotherapy, or combined with non–enzyme-inducing AEDs (non-EIAEDs) displayed a high 50% responder rate and seizure-free rate when compared with those in the late add-on, conversion therapy, or combined with the EIAEDs groups, respectively. Furthermore, the incidences of AEs at 3, 6, and 12 months of PER treatment were 46% (95% CI: 0.38–0.55), 52.0% (95% CI: 0.43–0.60), and 46.0% (95% CI: 0.40–0.52), respectively. The withdrawal rates due to AEs were 8.0% (95% CI: 0.06–0.11), 16.0% (95% CI: 0.13–0.20), and 16% (95% CI: 0.11–0.21) at 3, 6, and 12 months of PER treatment, respectively. Subgroup analyses showed a higher withdrawal rate in the rapid (30%, 95% CI: 0.22–0.38) than in the slow (12%, 95% CI: 0.06–0.18) titration group.

Conclusion: Altogether, PER was effective and could be fairly tolerated in both short-term and long-term usage in patients with epilepsy in routine clinical practice. Furthermore, PER appeared to be more effective when PER was used as the first add-on, monotherapy, or concomitant with non-EIAEDs.

Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022384532.

Kainate Receptor Antagonists: Recent Advances and Therapeutic Perspective

Since the 1990s, ionotropic glutamate receptors have served as an outstanding target for drug discovery research aimed at the discovery of new neurotherapeutic agents. With the recent approval of perampanel, the first marketed non-competitive antagonist of AMPA receptors, particular interest has been directed toward 'non-NMDA' (AMPA and kainate) receptor inhibitors. Although the role of AMPA receptors in the development of neurological or psychiatric disorders has been well recognized and characterized, progress in understanding the function of kainate receptors (KARs) has been hampered, mainly due to the lack of specific and selective pharmacological tools. The latest findings in the biology of KA receptors indicate that they are involved in neurophysiological activity and play an important role in both health and disease, including conditions such as anxiety, schizophrenia, epilepsy, neuropathic pain, and migraine. Therefore, we reviewed recent advances in the field of competitive and non-competitive kainate receptor antagonists and their potential therapeutic applications. Due to the high level of structural divergence among the compounds described here, we decided to divide them into seven groups according to their overall structure, presenting a total of 72 active compounds.

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 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.

Pharmacokinetics, tolerability, and clinical effectiveness of perampanel in Japanese patients with epilepsy

OBJECTIVE

We aimed to evaluate the influence of concomitant antiepileptic drugs (AEDs) on serum perampanel concentration and to correlate the concentration with clinical response and tolerability.

METHODS

A total of 4224 serum samples were obtained from 763 pediatric, adolescent, and adult patients for routine therapeutic drug monitoring. We compared the extent of enzyme induction between cytochrome P450 3A4 (CYP3A4) inducer regimens and built a statistical model to estimate the serum perampanel concentration that considered use of CYP3A4 inducers and inhibitors. To assess the tolerability and clinical effectiveness of perampanel therapy, we used the nested case-control approach. The case group was matched with the control group for age, sex, epilepsy type, and perampanel exposure periods.

RESULTS

Concomitant use of the inducers phenytoin, carbamazepine, and phenobarbital dose-dependently reduced the perampanel concentration by 51 %, 67 %, and 37 %, respectively. The estimate model showed a good correlation between the predicted and measured concentrations (r² = 0.62, p < 0.001). In 206 patients, the seizure reduction from baseline was > 50 % and the median perampanel concentration was 351 ng/mL (interquartile range, 191-603 ng/mL). Adverse events, such as somnolence, dizziness, and irritability, were experienced by 185 patients. The responder odds ratio was 5.1-fold higher in patients with a serum concentration > 600 ng/mL than in those with a serum concentration < 200 ng/mL; however, the former group had a 7.9-fold higher incidence of adverse events.

CONCLUSION

Therapeutic drug monitoring is clinically useful to assess drug interactions between perampanel and CYP3A4 inducers and inhibitors. We recommend that the target concentration of perampanel is initially set at 200-600 ng/mL. Serum concentrations > 600 ng/mL were associated with greater anti-seizure effects but had an increased risk of adverse events.

Effectiveness and safety of perampanel as early add-on treatment in patients with epilepsy and focal seizures in the routine clinical practice: Spain prospective study (PERADON)

OBJECTIVE

Perampanel (PER) has been shown to be effective as an adjunctive therapy for controlling refractory focal-onset seizures (FOS). However, the information as early add-on for the treatment of FOS in the clinical practice is still scarce and must be further assessed.

METHODS

An observational prospective study was conducted to evaluate the effectiveness of early add-on PER, assessed as 50% responders (seizure frequency reduced by at least 50% during the last 3 months as compared with baseline) rate at 6 and 12 months, in patients with FOS in the routine clinical practice of Spain.

RESULTS

One hundred and thirteen patients (mean age: 40.3 years, 51.3% male) with FOS received PER as early add-on (1st add-on: 37.2% and 2nd: 62.8%) for a mean exposure of 11 months (mean PER dose: 6.3 mg/day at month 12). At 6 months, 50.4% and 20.4% of the patients were responders and seizure-free (respectively) relative to baseline (3 months prior to PER initiation), and at 12 months, 68.1% and 26.5% of the patients were responders and seizure-free (respectively), relative to baseline (3 months prior to PER initiation). The retention rate at 6 and 12 months was 83.2% and 80.5%, respectively. The percentage of seizure-free patients at 12 months was significantly (p = 0.033) higher when PER was added as first vs. second add-on. The number of concomitant antiepileptic drugs (AEDs) was significantly reduced from baseline to 6 and 12 months (p = 0.001). Treatment was simplified in 23.9% of patients at the end of the observation period. Drug-related adverse events (AEs), most mild or moderate, were reported in 30.1% of patients, with irritability (8%) and dizziness (7.1%) as the most frequent ones.

CONCLUSIONS

This is the first observational, prospective study to evaluate efficacy and safety of early adjunctive treatment with PER in patients with focal epilepsy at 12 months. Perampanel demonstrated a good efficacy and safety profile when used at a median dose of 6 mg/day, regardless of the combination with other AEDs. Adverse events were mild or moderate, with dizziness being the most frequent one.

The value of human epileptic tissue in the characterization and development of novel antiepileptic drugs: The example of CERC-611 and KRM-II-81

The need for improved antiepileptics is clearly mandated despite the existence of multiple existing medicines from different chemical and mechanistic classes. Standard of care agents do not fully control epilepsies and have a variety of side-effect and safety issues. Patients typically take multiple antiepileptic drugs and yet many continue to have seizures. Antiepileptic-unresponsive seizures are life-disrupting and life-threatening. One approach to seizure control is surgical resection of affected brain tissue and associated neural circuits. Although non-human brain studies can provide insight into novel antiepileptic mechanisms, human epileptic brain is the bottom-line biological substrate. Human epileptic brain can provide definitive information on the presence or absence of the putative protein targets of interest in the patient population, the potential changes in these proteins in the epileptic state, and the engagement of novel molecules and their functional impact in target tissue. In this review, we discuss data on two novel potential antiepileptic drugs. CERC-611 (LY3130481) is an AMPA receptor antagonist that selectively blocks AMPA receptors associated with the auxiliary protein TARP γ-8 and is in clinical development. KRM-II-81 is a positive allosteric modulator of GABA_A receptors selectively associated with protein subunits α2 and α 3. Preclinical data on these compounds argue that patient-based biological data increase the probability that a newly discovered molecule will translate its antiepileptic potential to patients.