Cenobamate tablets as a treatment for focal-onset seizures in adults

The cenobamate KORK study-A prospective monocenter observational study investigating cenobamate as an adjunctive therapy in refractory epilepsy, with comparisons to historical cohorts treated with add-on lacosamide, perampanel, and brivaracetam

OBJECTIVE

In Europe, cenobamate has been approved for use as an adjunctive therapy in adult patients with epilepsy (PWE) with focal-onset seizures (FOS) who have not responded satisfactorily to treatment with at least two antiseizure medications (ASMs). Pivotal trials and real-world observational studies have demonstrated a high efficacy of cenobamate, even in very difficult-to-treat epilepsies. Our aim was to investigate the efficacy of add-on cenobamate in adult PWE who were prospectively monitored. We compared these results with those previously obtained for add-on lacosamide, perampanel, and brivaracetam therapy.

METHODS

Patients were enrolled from the CENKORK study, which is a prospective, non-interventional, open-label, monocenter cohort study of adult PWE experiencing FOS. The titration of cenobamate was performed according to the guidelines outlined in the summary of product characteristics. The primary outcome measure was the retention rate at 6 months and 1 year. In addition, we assessed seizure-free rates, the proportion of patients achieving at least a 50% seizure reduction, adverse events, and the reasons for treatment discontinuation. These outcome measures were compared with historical controls treated with adjunctive lacosamide, perampanel, or brivaracetam at our center.

RESULTS

Between June 2021 and 2022, 172 PWE with ongoing FOS were included. 22 cases were lost to follow-up, leaving 150 cases for the 1-year assessment. The retention rates at 6 months and 1 year were 88.7% and 80%, respectively. Seizure freedom was achieved in 14% of patients at both the 6-month and 1-year marks, while the ≥50% responder rates were 50% and 61%, respectively. The 6-month retention rate was significantly higher in cenobamate than in other ASMs (p < 0.001 for each comparator). Adverse events were significantly more common with perampanel (p < 0.001).

SIGNIFICANCE

Add-on cenobamate proved to be particularly efficacious compared to our experience with other recently introduced ASMs.

PLAIN LANGUAGE SUMMARY

This observational study was carried out in 172 adult patients with difficult-to-treat epilepsy who were treated with adjunctive cenobamate. After 1 year, the data of 150 patients could be analyzed. Seizure freedom, in the preceding 3 months, was achieved in 14%. The rate of PWE continuing cenobamate was 80%. In our hands, cenobamate showed promising efficacy and tolerability even when compared to other recently introduced antiseizure medications.

Cenobamate Plasma Levels in Patients with Epilepsy: Correlation with Efficacy and Tolerability?

Objective: Cenobamate is approved by the European Medicine Agency for the treatment of adult patients with epilepsy (PWEs) with ongoing focal-onset seizures despite appropriate treatment with at least two established antiseizure medications. Pivotal trials and post-marketing real-world observational studies suggest high efficacy with unusually high seizure-free rates. The authors sought to investigate the plasma levels of cenobamate under steady-state conditions in seizure-free versus non-responding PWEs, and in PWEs who experienced adverse events versus those who did not. Methods: Blood samples were collected from adult PWEs who were treated with adjunct cenobamate under steady-state conditions. Daily doses, concomitant medications, efficacy, and tolerability were assessed. The plasma cenobamate levels of seizure-free versus non-responding PWEs and between PWEs with and those without clinical adverse events were compared. Results: Samples from 101 PWEs were included. Thirty-six PWEs were seizure-free and 65 were non-responders. In 31 PWEs, adverse events were apparent, whereas in the remaining 70, no tolerability issues were reported. A linear correlation was found between the daily doses (range: 100 mg-400 mg) and the plasma levels (3.8 mg/L-54.6 mg/L). Neither the daily doses nor the plasma levels differed significantly between the investigated subgroups. The main reason for this result was that the individual therapeutic ranges varied widely: seizure freedom and adverse effects were observed alongside low doses and plasma levels in some PWEs. Conversely, there were examples of PWEs who did not respond or who reported no tolerability issues at high doses or plasma levels. Conclusions: To evaluate the individual therapeutic range and to better understand the influence of other drugs in cases where concomitant medications are used, the therapeutic drug monitoring of cenobamate may be useful. A general therapeutic range cannot be defined.

Add-on treatment with cenobamate is already effective at low doses in refractory focal epilepsy: A prospective observational study

OBJECTIVE

Cenobamate, a novel antiseizure medication with a dual mechanism of action, has been shown in pivotal trials to significantly improve seizure control in treatment-resistant focal epilepsy. We aimed to evaluate whether these promising results could be confirmed in a real-world setting with a follow-up period of up to 12 months.

METHODS

Patients from a tertiary epilepsy center who received cenobamate add-on between June 2021 and October 2023 were followed up prospectively at 3, 6, and 12 months after treatment initiation for assessment of seizure outcomes and treatment-related adverse events.

RESULTS

The clinical cohort included 112 adult patients with 30% nonlesional cases and a wide spectrum of epileptogenic lesions underlying refractory focal epilepsy. We observed a significant reduction in monthly seizure frequency of all seizure types already after 3 months of treatment at a median cenobamate dose of 100 mg/day. Forty-six percent of patients were responders with a ≥50% seizure reduction, 26% had a ≥75% seizure reduction, and 9% became seizure-free. Among the 74 patients with available follow-up of 12 months, the responder rates reached 55%, 35%, and 19% for ≥50%, ≥75%, and 100% seizure reduction, respectively. After 3 months of treatment, 38% of patients reported adverse effects, mainly (84%) mild to moderate in intensity. Adjustment of comedication allowed successful management of adverse effects in 32% of patients. At a group level, there was no correlation between the cenobamate daily dose and the incidence of adverse events.

SIGNIFICANCE

We found a clinically relevant response to cenobamate already at a low daily dose of 100 mg also in a patient cohort with a higher degree of drug resistance than in pivotal trials. Our prospectively collected data provide real-world evidence for high efficacy and good tolerability of the drug, although no standardized treatment protocol or comparison with a control group was applied.

Cenobamate (YKP3089) and Drug-Resistant Epilepsy: A Review of the Literature

Cenobamate (CNB), ([(R)-1-(2-chlorophenyl)-2-(2H-tetrazol-2-yl)ethyl], is a novel tetrazole alkyl carbamate derivative. In November 2019, the Food and Drug Administration approved Xcopri®, marketed by SK Life Science Inc., (Paramus, NJ, USA) for adult focal seizures. The European Medicines Agency approved Ontozry® by Arvelle Therapeutics Netherlands B.V.(Amsterdam, The Neatherlands) in March 2021. Cenobamate is a medication that could potentially change the perspectives regarding the management and prognosis of refractory epilepsy. In this way, this study aims to review the literature on CNB's pharmacological properties, pharmacokinetics, efficacy, and safety. CNB is a highly effective drug in managing focal onset seizures, with more than twenty percent of individuals with drug-resistant epilepsy achieving seizure freedom. This finding is remarkable in the antiseizure medication literature. The mechanism of action of CNB is still poorly understood, but it is associated with transient and persistent sodium currents and GABAergic neurotransmission. In animal studies, CNB showed sustained efficacy and potency in the 6 Hz test regardless of the stimulus intensity. CNB was revealed to be the most cost-effective drug among different third-generation antiseizure medications. Also, CNB could have neuroprotective effects. However, there are still concerns regarding its potential for abuse and suicidality risk, which future studies should clearly assess, after which protocols should be changed. The major drawback of CNB therapy is the slow and complex titration and maintenance phases preventing the wide use of this new agent in clinical practice.

Cenobamate significantly improves seizure control in intellectually disabled patients with drug-resistant epilepsy and allows drug load reduction

Introduction

Epilepsy patients with intellectual disability often suffer from drug-resistant epilepsy (DRE), which severely affects patients' quality of life. Cenobamate (CNB) is a recently approved novel and effective ASM that can achieve high rates of seizure freedom in previously drug-resistant patients.

Methods

We performed a retrospective data analysis of the first patients treated with CNB at a single center. Outcome and treatment response were assessed at two different time points, and ASM burden was calculated.

Results

A 12 patients (7 males and 5 females) began treatment at a median age of 43 years, six of whom had developmental and epileptic encephalopathies. Prior to treatment with CNB, patients had tried a median of 13 different ASM. At the start of CNB therapy, patients were taking a median of 3 ASM. Treatment outcomes were available for 11 patients. After the first follow-up period (median 9 months), 55% of patients showed a significant seizure reduction of more than 50%, with three patients showing a reduction of more than 75% (27%). One patient achieved complete seizure freedom, while one patient did not respond to treatment. These response rates were consistently maintained at second follow-up after a median of 22 months. Ten patients (83%) reported adverse events (AE), the most common of which were dizziness and fatigue. No cases of drug reactions with eosinophilia and systemic symptoms (DRESS) were observed. The majority of AEs were mild and resolved over time. In addition, most patients were able to reduce their concomitant ASM.

Discussion

Cenobamate has been shown to be an effective ASM in patients with DRE and in patients with intellectual disabilities. After more than 1 year of treatment with CNB, close monitoring and management of drug-drug interactions may reduce enzyme-inducing ASMs and lead to better long-term outcomes. With CNB treatment, many patients can achieve a reduced overall drug burden while maintaining a reduction in seizures.

Is Cenobamate the Breakthrough We Have Been Wishing for?

Close to one-third of patients with epilepsies are refractory to current anti-seizure medications; however, trials with cenobamate suggest effectiveness in such patients with focal onset seizures. We searched for data published or otherwise reported on cenobamate and outlined these here. Despite being marketed in the USA, few studies are yet published in full, and trials are ongoing. Nevertheless, cenobamate showed potential for a high degree of efficacy in reducing seizures with an unprecedented seizure-free rate of up to 28%. Rare cases of hypersensitivity reactions seen in early trials seem to be avoided by the current recommended titration schedule. Other adverse events were rated mild-to-moderate and most commonly included dizziness, drowsiness, and headache. If data are confirmed in further published trials, cenobamate will be a welcome new treatment and further analyses may identify those that will benefit the most.