"I tried every medication that existed; however, nothing would minimise, let alone, stop the seizures"1
This statement highlights a common experience for doctors and their patients with epilepsy: the ongoing search for effective therapies that can provide lasting relief from seizures. Finding the right treatment regimen often involves navigating a complex landscape of treatment options.1
Cenobamate, an adjunctive treatment for focal-onset seizures in adults, offers an interesting mechanism of action with its dual antiseizure activity. It promotes the inactivated state of voltage-gated sodium channels, blocking persistent sodium currents, and acts as a positive allosteric modulator of GABAA receptors at a site distinct from benzodiazepines.2
The following data deepdive will give you an overview of cenobamate's potential in achieving the seizure freedom and how real-world experience reflects the learnings from clinical trials.
Cenobamate treatment has been associated with considerable seizure freedom rates in two pivotal trials enrolling 659 patients.3 Efficacy of cenobamate was demonstrated in studies C013 and C017, two randomized, double- blind, placebo-controlled, multicenter studies (treatment lengths ≤ 18 weeks) in adults with uncontrolled focal seizures despite taking 1–3 ASMs.4
Study C013 reported seizure freedom in 28.3% of participants administered 200 mg/day of cenobamate (vs 8.8% of those taking placebo)5; Study C017 demonstrated seizure freedom in 21% of participants taking 400 mg/day of cenobamate (vs 1% with placebo).5
The results observed in clinical trials are similar in real-world settings, with higher dosages needed to achieve seizure freedom.2
Pietrafusa et al 2023: A retrospective study conducted at two Italian epilepsy centers evaluated the effectiveness of cenobamate (CNB) as an add-on treatment in 54 adult patients (median age: 27.9 years) with drug-resistant focal epilepsy. All patients received cenobamate through Angelini Pharma's Early Access Program (EAP) between 2020 and 2022. Seizure outcome, treatment-emergent adverse events, neuropsychological profile, and blood levels of CNB and concomitant ASMs were analyzed.3
Study population
All patients treated with add-on CNB, aged ≥18 years and diagnosed with drug-resistant focal epilepsy were included. The patients were taking in median of 3 ASMs and had been treated with median of 9 ASMs. 29.6% had vagal nerve stimulation therapy 35.2% had failed epilepsy surgery.3
Baseline period
The 4 weeks before starting CNB. Efficacy outcomes were evaluated at 3, 6, 9 and 12 months after the introduction of CNB. The primary efficacy endpoint was the percentage change in monthly baseline seizure frequency at the last follow-up visit (LFV). The seizure frequency up to the LFV was calculated as the number of seizures recorded during the treatment with CNB (including both the titration and maintenance phase), divided by the number of days from the initiation of CNB to the LFV. The result was multiplied by 28 to obtain a monthly frequency.3
Outcome
Following
CNB administration, a clinically meaningful reduction in seizure frequency was observed in most patients: 42.0% experienced a >75% reduction in baseline seizure frequency, and 20.2% achieved seizure freedom.3 At LFV the median dose of CNB was 201.8 mg/day. Nearly 60% of patients were able to reduce or withdraw one or more concomitant ASMs. None of the patients experiences significant alterations in QTc interval and no significant blood test alterations were registered. CNS-related side effects were the most reported. Ataxia and diplopia were more frequent with concomitant SCB in treatment regimen, likely explained by pharmacodynamic interaction. Many cases were resolved by lowering the number or dose of concomitant ASMs. In this real-world study cenobamate demonstrated to be tolerable and it provided sustained, clinically meaningful seizure reduction.3
Spanish Expanded Access Program (EAP) between August 2020 - June 2022: A multicenter, retrospective, observational study investigated real-world outcomes with cenobamate in a large cohort of patients (n=170) with highly drug-resistant epilepsy.2
Study population and baseline
Patients were over 18 years old, diagnosed with focal onset seizures and considered highly drug-resistant. The patient population had been treated in median of 12 ASMs and were taking in median 3 concomitant ASMs, of which lacosamide (35.9%), brivaracetam (35.3%), carbamazepine (34.1%), and clobazam (31.8%) were the most used. Many of the patients would have been ineligible for inclusion in the clinical trials based on their number of concomitant ASMs, their psychiatric comorbidities, or their recent history of status epilepticus.2
Mean CNB dosages/day were 176 mg, 200 mg, and 250 mg at 3, 6, and 12 months. The study data suggests that many patients experienced clinically relevant seizure reductions at cenobamate dose of 100 or 200 mg/day , but it seems that higher dosages were needed to achieve seizure freedom, particularly in the long term.2
This study showed that 63% of patients achieved a ≥50% reduction in seizure frequency, and 13.3% of patients were seizure-free at their last visit.2 The percentage, type, and severity of adverse events in this study were similar to those reported in clinical trials. The most frequent adverse events were somnolonce and dizziness. No body skin rashes were reported and there were no cases of drug reaction with eosinophilia and systemic symptoms (DRESS) or hypersensitivity syndrome (HSS). A particular tendency for a dose reduction or discontinuation of concomitant SCBs and clobazam was observed, similarly to earlier findings in post-hoc analysis of a CNB clinical trial C021. Efficacy of cenobamate in this study did not depend on the number of concomitant ASMs.2
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Ontozry® (cenobamat) 12,5 mg odragerad tablett samt 25 mg, 50 mg, 100 mg, 150 mg och 200 mg filmdragerade tabletter. Rx F. ATC-kod: N03AX25 - antiepileptika, övriga antiepileptika. Indikation: Ontozry är indicerat som tilläggsbehandling av fokala anfall, med eller utan sekundär generalisering hos vuxna patienter med epilepsi, som inte kontrollerats tillräckligt trots tidigare behandling med minst två antiepileptika. Kontraindikationer: Överkänslighet mot den aktiva substansen eller mot något hjälpämne, ärftligt kort QT-syndrom. Varningar: Patienter ska instrueras att uppsöka läkare om tecken på självmordstankar/självmordsbeteende uppstår, samt om tecken och symptom på läkemedelsreaktion med eosinofili och systemiska symtom (DRESS) inträffar. Innehåller laktos. Cenobamat kan minska exponeringen av substanser som metaboliseras via CYP3A4, CYP2B6 samt öka exponeringen av substanser som metaboliseras via CYP2C19. Cenobamat rekommenderas inte till fertila kvinnor som inte använder preventivmedel eller vid amning. MAH: Angelini Pharma S.p.A. Lokal kontakt: Angelini Pharma Nordics, nordic.medinfo@angelinipharma.com. Datum för senaste översyn av SPC: 9/2025. För pris och ytterligare information, se www.fass.se.