[Cenobamate-a new perspective for epilepsy treatment]

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 in Generalized Epilepsy and Combined Generalized and Focal Epilepsy

Background and Objectives

Cenobamate (CNB) is a United States Food and Drug Administration–approved antiseizure medication (ASM) for focal-onset seizures; however, its potential clinical effectiveness as a broad-spectrum ASM is not established. CNB has a proposed dual mechanism of action with preferential blockade of persistent sodium currents and positive allosteric modulation of the γ-aminobutyric acid-A (GABA-A) receptor. We evaluated the efficacy of CNB in drug refractory patients with genetic generalized epilepsies (GGE) or combined generalized and focal epilepsies (CGFE), including developmental and epileptic encephalopathies.

Methods

We performed a retrospective review and identified the following: cohort 1 (n = 4) with GGE, of which 2 patients had idiopathic generalized epilepsy, and cohort 2 with CGFE (n = 9), of which 4 patients had Lennox-Gastaut syndrome and 1 had Dravet syndrome.

Results

In cohort 1, all 3 patients with frequent generalized tonic-clonic seizures (GTCs) had a greater than 50% reduction in GTCs. In cohort 2, reduction in both generalized and focal-onset seizures was noted. In these groups together, the mean reduction of all seizure types was 58%, and ≥50% responder rate was 70% (SD = ±34.16, median = 50%). No worsening of generalized-onset seizures occurred in either cohort. Seventy-seven percent of patients experienced side effects, warranting a modification of treatment managed by slower titration, dose reduction of CNB, or discontinuing other ASMs.

Discussion

In our retrospective case series, CNB seems to be an effective ASM for patients with drug-resistant GGE and CGFE. The ongoing CNB trial assessing effectiveness for primary GTCs will provide more data on generalized-onset seizures.

Classification of Evidence

This study provides Class IV evidence that CNB in generalized epilepsy and combined generalized and focal epilepsy reduces seizure frequency.

Determination of the economically justifiable price of cenobamate in the treatment of focal-onset seizures in adult patients with drug-resistant epilepsy in Spain

OBJECTIVE

To determine the economically justifiable price (EJP) of cenobamate to become a cost-effective alternative compared with third-generation anti-seizure medications in the treatment of focal-onset seizures (FOS) in adult patients with drug-resistant epilepsy (DRE) in Spain.

METHODS

Cost-effectiveness analysis comparing cenobamate with brivaracetam, perampanel, eslicarbazepine acetate and lacosamide. Markov model simulation of treatment pathway over a 60-year time horizon. Determination of effectiveness and quality-adjusted life-years (QALYs) of each health status, and disutilities associated with treatment-related adverse events. Acquisition costs and use of medical resources were obtained from published literature and expert opinion. Base-case of cenobamate's EJP calculated applying a willingness-to-pay (WTP) threshold of €21,000/QALY. Analyses performed at different thresholds, including dominant price scenario. Results robustness were assessed through sensitivity analyses.

RESULTS

Base-case shows that cenobamate's daily EJP of €7.30 is cost-effective for a threshold of €21,000/QALY. At a daily price of €5.45, cenobamate becomes dominant over all treatment alternatives producing cost-savings for the national health system (NHS). Sensitivity analyses supported the robustness of base-case findings.

CONCLUSIONS

Treatment with cenobamate produces incremental clinical benefit over third generation ASMs and at the base-case EJP could represent a cost-effective option for the adjunctive treatment of FOS in adult patients with DRE in Spain.

[Epilepsy in the elderly]

The incidence rate of epilepsy has importantly increased during the last decades due to the rising expectation of life. Special clinical aspects have to be considered for the correct diagnosis and differential diagnosis of epileptic seizures in the elderly: On one hand, the etiology of epilepsy in the elderly is different from epilepsies of younger people with a higher rate of symptomatic epilepsies compared to younger people. On the other hand, seizures are more often clinically inconclusive as they frequently appear without motor symptoms and therefore require an accurate diagnostic differentiation from other attacks of unconsciousness. The most accurate diagnostic tool for the correct diagnosis of such seizures is the registration of the seizures by longtime-video-EEG-monitoring (LTVEM). If LTVEM cannot be performed also home-video-registration could be useful. Medical treatment of epilepsies in the elderly has to be done with special consideration of comorbidity and metabolic changes in this age group.