Suppression of the photoparoxysmal response in photosensitive epilepsy with cenobamate (YKP3089)

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 in refractory epilepsy: Overview of treatment options and practical considerations

Management of drug resistant epilepsy (DRE) represents a challenge to the treating clinician. This manuscript addresses DRE and provides an overview of treatment options, medical, surgical, and dietary. It addresses treatment strategies in polytherapy, then focuses on the role cenobamate (CNB) may play in reducing the burden of DRE while providing practical advice for its introduction. CNB is a recently approved, third generation, anti-seizure medication (ASM), a tetrazole-derived carbamate, thought to have a dual mechanism of action, through its effect on sodium channels as well as on GABAA receptors at a non-benzodiazepine site. CNB, having a long half-life, is an effective add-on ASM in refractory focal epilepsy with a higher response rate and a higher seizure-freedom rate than is usually seen in regulatory clinical trials. Experience post-licensing, though still limited, supports the findings of clinical trials and is encouraging. Its spectrum of action in relation to generalized epilepsies and seizures remains to be established, and there are no data on its efficacy in monotherapy. At the time of writing, CNB has been prescribed for some 50 000 individuals with DRE and focal epilepsy. A larger number is needed to fully establish its safety profile. It should at all times be introduced slowly to minimize the risk of serious allergic drug reactions. It has clinically meaningful interactions which must be anticipated and managed to maximize tolerability and likelihood of successful treatment. Despite the above, it may well prove to be of major benefit in the treatment of many patients with drug resistant epilepsy.

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.

Asymmetric Synthesis of US-FDA Approved Drugs over Five Years (2016–2020): A Recapitulation of Chirality

Chirality is a major theme in the design, discovery, and development of new drugs. Historically, pharmaceuticals have been synthesized as racemic mixtures. However, the enantiomeric forms of drug molecules have distinct biological properties. One enantiomer may be responsible for the desired therapeutic effect (eutomer), whereas the other may be inactive, interfere with the therapeutic form, or exhibit toxicity (distomer). Classical chemical synthesis usually leads to a racemic mixture unless stereospecific synthesis is employed. To meet the requirements of single-enantiomeric drugs, asymmetric synthesis has evolved at the forefront of drug discovery. Asymmetric synthesis involves the conversion of an achiral starting material into a chiral product. This review emphasizes the methods used for synthesizing FDA-approved chiral drugs during 2016–2020, with a special focus on asymmetric synthesis by means of chiral induction, resolution, or chiral pool.

Myoclonus as a Manifestation of Reflex Seizures

SUMMARY

Myoclonus is a motor symptom commonly associated with reflex seizures in people with idiopathic generalized epilepsies. The most frequently observed triggers of myoclonus are related to visual stimuli, including flashing lights or patterns; nonetheless, myoclonus can also be activated by movement, speech or reading, calculations, and praxis. Reflex myoclonic seizures may be the hallmark of a reflex epilepsy, but it may lead to the diagnosis of generalized epilepsy syndromes. In the setting of idiopathic generalized epilepsies, reflex myoclonus can persist despite optimal medical therapies and may be a marker for active, even medically intractable, epilepsy. In this article, the clinical significance, diagnosis, and treatment of myoclonus, associated with visual stimulation, movement, and praxis, will be reviewed.

Successful treatment of adult Dravet syndrome patients with cenobamate

Dravet syndrome (DS) is a rare, drug-resistant, severe developmental and epileptic encephalopathy caused by pathogenic variants in the α subunit of the voltage-gated sodium channel gene SCN1A. Hyperexcitability in DS results from loss of function in inhibitory interneurons. Thus sodium channel blockers are usually contraindicated in patients with DS as they may lead to disease aggravation. Cenobamate (CNB) is a novel antiseizure medication (ASM) with promising rates of seizure freedom in patients with focal-onset, drug-resistant epilepsy. CNB blocks persistent sodium currents by promoting the inactive states of sodium channels. In a multi-center study, we analyzed retrospectively the effect of an add-on therapy of CNB in adult patients with DS. We report four adult patients with DS in whom the use of CNB resulted in a significant seizure reduction of more than 80%, with a follow-up of up to 542 days. CNB was the first drug in these patients that resulted in a long-lasting and significant seizure reduction. No severe adverse events occurred. We highlight CNB as an ASM that may lead to a clinically meaningful reduction of seizure frequency in adult patients with DS. It is unclear, however, if all patients with DS benefit, requiring further investigation and functional experiments.

Visually sensitive seizures: An updated review by the Epilepsy Foundation

Light flashes, patterns, or color changes can provoke seizures in up to 1 in 4000 persons. Prevalence may be higher because of selection bias. The Epilepsy Foundation reviewed light-induced seizures in 2005. Since then, images on social media, virtual reality, three-dimensional (3D) movies, and the Internet have proliferated. Hundreds of studies have explored the mechanisms and presentations of photosensitive seizures, justifying an updated review. This literature summary derives from a nonsystematic literature review via PubMed using the terms "photosensitive" and "epilepsy." The photoparoxysmal response (PPR) is an electroencephalography (EEG) phenomenon, and photosensitive seizures (PS) are seizures provoked by visual stimulation. Photosensitivity is more common in the young and in specific forms of generalized epilepsy. PS can coexist with spontaneous seizures. PS are hereditable and linked to recently identified genes. Brain imaging usually is normal, but special studies imaging white matter tracts demonstrate abnormal connectivity. Occipital cortex and connected regions are hyperexcitable in subjects with light-provoked seizures. Mechanisms remain unclear. Video games, social media clips, occasional movies, and natural stimuli can provoke PS. Virtual reality and 3D images so far appear benign unless they contain specific provocative content, for example, flashes. Images with flashes brighter than 20 candelas/m² at 3-60 (particularly 15-20) Hz occupying at least 10 to 25% of the visual field are a risk, as are red color flashes or oscillating stripes. Equipment to assay for these characteristics is probably underutilized. Prevention of seizures includes avoiding provocative stimuli, covering one eye, wearing dark glasses, sitting at least two meters from screens, reducing contrast, and taking certain antiseizure drugs. Measurement of PPR suppression in a photosensitivity model can screen putative antiseizure drugs. Some countries regulate media to reduce risk. Visually-induced seizures remain significant public health hazards so they warrant ongoing scientific and regulatory efforts and public education.

Pharmacokinetics and safety of cenobamate, a novel antiseizure medication, in healthy Japanese, and an ethnic comparison with healthy non-Japanese

Cenobamate (XCOPRI and ONTOZRY) is a novel antiseizure medication for the treatment of focal-onset seizures. Nonetheless, there is limited information on the pharmacokinetics (PKs), safety, and efficacy of cenobamate in Asian people, including Japanese people. This study aimed to evaluate the PKs and safety of cenobamate after a single oral dose in healthy Japanese subjects and to compare the PKs with that reported in non-Japanese subjects. A randomized, double-blind, placebo-controlled, single ascending dose study was conducted at four dose levels of 50, 100, 200, and 400 mg. Subjects were randomly assigned to cenobamate or placebo in a 6:2 ratio. Cenobamate was rapidly absorbed, reaching its maximum plasma concentration (C_max ) in 0.75 to 2.25 h, and was eliminated with a mean half-life of 37.0 to 57.7 h. The C_max increased dose proportionally, whereas area under the concentration-time curve increased more than dose proportionally, which was consistent with the findings in non-Japanese subjects. The systemic exposure of cenobamate was comparable between Japanese and non-Japanese subjects at all dose levels evaluated. All adverse events were mild in severity, and their incidence did not show dose-dependent trends. Furthermore, there were no clinically significant issues in safety parameters, including sedation tests, neurologic examinations, and Columbia Suicide Severity Rating Scale interviews. In conclusion, the systemic exposure of cenobamate after a single dose in Japanese subjects increased by dose, which was similar to the pattern in non-Japanese subjects. In addition, a single dose of cenobamate was well-tolerated in the dose range of 50 to 400 mg in healthy Japanese subjects.

Efficacy of color lenses in abolishing photosensitivity: Beyond the one-type-fits-all approach?

OBJECTIVE

Red-light filtering lenses represent an additional option to medication in photosensitive epilepsy. Blue lenses (Clarlet Z1 F133) can dramatically reduce seizure frequency, with a substantial restriction in luminance that can limit their applicability in daily life. We investigated the efficacy of 4 blue lenses with higher transmittance and reduced chromatic distortion in abolishing the photoparoxysmal EEG response (PPR) compared to the gold-standard Z1 lenses.

METHODS

We reviewed EEG data during photic-and pattern stimulation in 19 consecutive patients (6-39 years) with photosensitivity (PS). Stimulation was performed at baseline and while wearing Z1 and the four new lenses. Lenses were tested in the same session by asking the patient to wear them in a sequentially randomized fashion while stimulating again with the most provocative photic/pattern stimuli. The primary outcome was the change in the initial PPR observed for each lens, categorized as no change, reduction, and abolition.

RESULTS

Photosensitivity was detected in 17 subjects (89.5%); pattern sensitivity (PtS) was identified in 14 patients (73.7%). The highest percentages of PPR abolition/reduction were observed with Z1, for both PS and PtS. Regarding the new lenses, B1 + G1 offered the best rates, followed by B1 + G2. B1 + G3 and B1 showed lower efficacy rates, particularly for PtS. In the comparative analysis, no significant differences in PPR suppression were detected between the five lenses for PS. For PtS, the capacity of Z1 for PPR abolition was significantly higher compared with B1 + G3 and B1.

CONCLUSIONS

This preliminary study suggests efficacy of the new group of blue lenses with potentially greater tolerability, particularly in regions with fewer sunlight hours during winter. In line with the current trend for personalized approach to treatment, this study suggests that in some patients there might be scope in extending the testing to offer the lens with the higher transmittance effective in abolishing the PPR.

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.

Efficacy and safety of cenobamate in patients with uncontrolled focal seizures: A meta-analysis

OBJECTIVE

To investigate the efficacy and safety of adjunctive cenobamate for treatment of uncontrolled focal seizures.

METHODS

We performed a systematic search of Web of Science, MEDLINE (Ovid and PubMed), Cochrane Library, EMBASE and Google Scholar to identify eligible studies. We included randomized placebo-controlled trials (RCTs) for uncontrolled focal seizures. We calculated the risk ratio (RR) of ≥50%, ≥75% and 100% reduction in seizure frequency from baseline, as well as dropout and serious adverse events related to treatment. Quality of included trials was assessed using the Cochrane Collaboration's tool.

RESULTS

Two RCTs with a total of 658 patients were included. A significantly larger proportion of patients allocated to cenobamate achieved 50% seizure reduction (RR 2.06, 95% CI 1.70-2.51, p < 0.001) as compared to placebo, subgroup analysis demonstrated that the most effective dose was at 400 mg (RR 2.28, 95% CI 1.57-3.32, p < 0.001). Patients achieving seizure-freedom during the treatment period were 14.9% with cenobamate and 4.5% with placebo (RR 5.32, 95% CI 2.94-9.62, p < 0.001). Dropouts (RR 1.40, 95% CI 1.01-1.94, p = 0.05) and incidence of serious adverse events (RR 1.48, 95% CI 0.93-2.33, p = 0.1) were not significantly higher in patients receiving cenobamate. However, subgroup analyses based on doses suggested that patients exposed to 400 mg cenobamate were more likely to dropout than placebo (RR 2.09, 95% CI 1.17- 3.71, p = 0.012).

CONCLUSION

Cenobamate demonstrated favourable efficacy for treatment of uncontrolled focal seizures and showed a dose-related fashion. Cenobamate could be well tolerated, the most common adverse events associated with cenobamate were dizziness, somnolence, fatigue, headache and nausea. Nevertheless, majority of them were mild to moderate in severity.

Cenobamate, a Sodium Channel Inhibitor and Positive Allosteric Modulator of GABAA Ion Channels, for Partial Onset Seizures in Adults: A Comprehensive Review and Clinical Implications

Medical management of epilepsy seeks to eliminate or to reduce the frequency of seizures, help patients maintain a normal lifestyle, and maintain psychosocial and occupational activities, while avoiding the negative side effects of long-term treatment. Current FDA approved drugs have been shown to have similar efficacy; however, they all share a commonality of having side effects that have the potential to significantly reduce a patient’s quality of life. Cenobamate, a newly-FDA approved drug used to treat partial-onset seizures in adult patients, has demonstrated promise in that it works on two proposed mechanisms that are commonly associated with epilepsy. Cenobamate acts as a positive allosteric modulator of the GABA_A ion channels and is effective in reducing repetitive neuronal firing by inhibition of voltage-gated sodium channels, although the complete mechanism of action is currently unknown. The efficacy of Cenobamate with its low toxicity and adverse drug reaction profile emphasizes the need to further evaluate antiepileptic therapies containing sulfamoylphenyl and/or carbamate moieties in their chemical structure. Recent studies have found more patients to be seizure free during the maintenance period when compared to placebo. The most common side effects reported in with Cenobamate are somnolence, dizziness, headache, nausea, and fatigue. There are currently ongoing phase III studies looking to further evaluate the long-term benefits of Cenobamate and investigate adverse events.

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

Introduction: Despite the introduction of numerous new antiseizure medications (ASMs) still about one-third of epilepsies remain drug-resistant. Therefore, new compounds with advanced efficacy are urgently needed. Cenobamate (CNB) is a new ASM that has been recently introduced in the United States for the treatment of adults with focal-onset seizures. The approval in Europe is under way.Areas covered: This review covers the pharmacological profile of CNB, the proof-of-concept trial, the two double-blind, placebo-controlled phase 2 trials investigating adjunct CNB in adults with focal-onset seizures, one open-label safety trial, and a variety of published abstract material that provided additional post hoc data.Expert opinion: In two placebo-controlled randomized multicenter phase 2 trials adjunct CNB showed unusually high efficacy with rates of seizure-free people with epilepsy (PWE) partially beyond 20%. However, during the clinical program cases of drug-related reactions with eosinophilia and systemic symptoms (DRESS syndrome) occurred. Therefore, an open-label safety study was performed in more than 1300 PWE with particularly slower titration schedules which did not add more cases with similar reactions. Taking into consideration the promising efficacy and the safety experience from the open-label trial, CNB applied according to the meanwhile recommended titration strategy, might offer a new prospect.

Critical Appraisal of Cenobamate as Adjunctive Treatment of Focal Seizures in Adults

Cenobamate (CNB) is the latest antiseizure medication (ASM) authorized for the treatment of focal-onset seizures in adults. Although the precise mechanism of action of CNB is not yet fully understood, this drug inhibits the persistent, rather than transient, voltage-gated sodium channel currents and is a positive allosteric modulator of synaptic and extrasynaptic GABA_A receptors, differently from benzodiazepines. CNB has a non-linear pharmacokinetic with a terminal half-life range of about 50/60 hours within the therapeutic dose range, which allows once daily administration. Cenobamate inhibits cytochrome P450 (CYP) 2C19 and induces CYP3A4 and 2B6, and hence can potentially interact with ASMs (eg, phenytoin, carbamazepine and clobazam) and no-ASMs drugs. In two randomized, double-blind, placebo-controlled trials in patients with focal epilepsies, CNB has shown a particularly good efficacy with a rate of seizure freedom of about 20% during the maintenance period in participants treated with the dose of 400 mg/day. The most common treatment-emergent adverse effects include central nervous system-related symptoms, like dizziness, diplopia, somnolence, and gait disturbances. Safety issues of particular interest are severe skin reactions (drug reaction with eosinophilia and systemic symptoms) and QT shortening, which contraindicates its use in subjects with familial short QT syndrome or in combination with other QT-shortening drugs. The recommended starting dose is 12.5 mg/day, which can be gradually titrated to the target dose (200 mg/day) and further increased up to 400 mg/day. There are several aspects of CNB that need to be still addressed, including the long-term efficacy and the efficacy in patients with generalized seizures. Ongoing studies will clarify these issues. The clinical relevance of the peculiar pharmacokinetics and the pattern of drug-drug interactions also require further investigation.

Pharmacological treatment of focal epilepsy in adults: an evidence based approach

INTRODUCTION

Focal seizures represent the most common seizure type and focal epilepsies the most common epilepsy type. Anti-seizure medications (ASMs) still represent the main form of treatment for epilepsy.

AREAS COVERED

The aim of this review article is to provide an overview of available evidence about current and upcoming pharmacological options and strategies for adults with focal epilepsy focusing on the last 5 years.

EXPERT OPINION

Seventeen drugs are currently approved for the treatment of focal seizures including cenobamate as the very latest option. Ten of these drugs are also licensed for monotherapy. Level A evidence for initial monotherapy is available for seven drugs with no robust data supporting that one drug is superior to the other. Safety, tolerability as well as pharmacoeconomic reasons would then drive treatment decisions. Data on adjunctive treatment are available for 13 ASMs showing again no obvious difference in terms of efficacy. Evidence on specific drug combinations is almost non-existent and the final decision of combining specific drugs is based on the experience of the individual clinician rather than on robust evidence. Current outcome measures do not consider number of previously failed drugs and the observation period is often too short.

Recent advancement in the discovery and development of anti-epileptic biomolecules: An insight into structure activity relationship and Docking

Although there have been many advancements in scientific research and development, the cause of epilepsy still remains an open challenge. In spite of high throughput research in the field of anti-epileptic drugs, efficacy void is still prevalent before the researchers. Researchers have persistently been exploring all the possibilities to curb undesirable side effects of the anti-epileptic drugs or looking for a more substantial approach to diminish or cure epilepsy. The drug development has shown a hope to medicinal chemists and researchers to carry further research by going through a substantial literature survey. This review article attempts to describe the recent developments in the anti-epileptic agents, pertaining to different molecular scaffolds considering their structure-activity relationship, docking studies and their mechanism of actions.

[Cenobamate-a new perspective for epilepsy treatment]

In spite of the introduction of numerous new antiseizure drugs (ASD) over the last decades, the percentage of drug-resistant epilepsies has remained almost stable. To achieve seizure freedom in such patients with any modified ASD regimen is an exception. Cenobamate (CNB) is a new ASD that showed unusually high efficacy in the pivotal placebo controlled, randomized trials. In both studies (C013 and C017), the rate of seizure-free patients was sometimes more than 20% and thus in a range never reached over the last decades in comparable trials with other new ASDs. This suggests that CNB which is already approved in the USA might actually offer a new and encouraging perspective for epilepsy treatment concerning efficacy. In this review the pharmacological profile, the currently known mode of action, and the results of the clinical trials are summarized.

Cenobamate for the treatment of focal epilepsies

INTRODUCTION

Antiseizure drugs (ASDs) play a central and crucial role in the treatment of epilepsy patients because the majority require anticonvulsant treatment for an extended period of time. Due to the fact that 30% of patients are refractory to medical treatment, new therapeutic options are necessary. Cenobamate is the latest approved antiepileptic drug in focal epilepsy, and its mode of action is thought to be mediated by blocking voltage-gated sodium channels and interaction with the GABAergic system.

AREAS COVERED

This article reviews animal studies, pharmacokinetics, pharmacodynamics, and the phase 1 to 3 trials and open-label extension data on cenobamate.

EXPERT OPINION

Cenobamate has the potential to perform as an important ASD because trial data are indicative of remarkable responder and seizure freedom rates so far not seen with other ASDs. Cenobamate demonstrated significant efficacy at a dosage between 100 and 400 mg per day. The side-effect profile of this drug is comparable to other ASDs and is mainly CNS related; in particular, somnolence, dizziness, headache, diplopia, and nystagmus. However, slow titration is mandatory to decrease the risk of drug rash with eosinophilia and systemic symptoms (DRESS) that was observed in several patients with fast uptitration schemes.

Cenobamate: First Approval

Cenobamate (XCOPRI^®) is an oral, small molecule neurotherapeutic azole compound that is being developed by SK Life Science Inc. and Arvelle Therapeutics for the treatment of epilepsy. Based on results of two pivotal phase 2 trials, cenobamate was recently approved in the USA for use in the treatment of partial-onset seizures in adult patients. This article summarizes the milestones in the development of cenobamate leading to this first approval.

Light-emitting-diode and Grass PS 33 xenon lamp photic stimulators are equivalent in the assessment of photosensitivity: Clinical and research implications

The assessment of the effect of photic stimulation is an integral component of an EEG exam and is especially important in patients referred for ascertained or suspected photosensitivity with or without a diagnosis of epilepsy. A positive test result relies on eliciting a specific abnormality defined as the "photoparoxysmal response". Reliability of this assessment is strongly influenced by technical and procedural variables, a critical one represented by the physical properties of the stimulators used. Established clinical norms are based on data acquired with the "gold-standard" Grass PS stimulators. These are no longer commercially available and have been replaced by stimulators using light emitting diode (LED) technology. To our knowledge no comparative study on their efficacy has been conducted. To address this gap, we recruited 39 patients aged 5-54 years, referred to two specialized centers with confirmed of suspected diagnosis of photosensitive epilepsy or generalized epilepsy with photosensitivity in a prospective randomized single-blind cross-over study to compare two commercially available LED-bases stimulation systems (FSA 10® and Lifeline® stimulators) against the Grass PS 33 xenon lamp device. Our findings indicate that the LED systems tested are equivalent to the Grass stimulator both in identifying the PPR in affected individuals.

Randomized phase 2 study of adjunctive cenobamate in patients with uncontrolled focal seizures

Objective

To evaluate the efficacy and safety of adjunctive cenobamate 200 mg/d in patients with uncontrolled focal (partial-onset) seizures despite treatment with 1 to 3 antiepileptic drugs.

Methods

In this multicenter, double-blind, placebo-controlled study, adults 18 to 65 years of age with focal seizures were randomized 1:1 (cenobamate:placebo) after an 8-week baseline period. The 12-week double-blind treatment period consisted of a 6-week titration phase and a 6-week maintenance phase. The primary outcome was percent change in seizure frequency (from baseline) per 28 days during double-blind treatment.

Results

Two hundred twenty-two patients were randomized; 113 received cenobamate and 109 received placebo; and 90.3% and 90.8% of patients, respectively, completed double-blind treatment. Median baseline seizure frequency was 6.5 in 28 days (range 0–237). Compared to placebo, cenobamate conferred a greater median percent seizure reduction (55.6% vs 21.5%; p < 0.0001) The responder rate (≥50% reduction in seizure frequency) was 50.4% for cenobamate and 22.2% for placebo (p < 0.0001). Focal seizures with motor component, impaired awareness, and focal to bilateral tonic-clonic seizures were significantly reduced with cenobamate vs placebo. During maintenance, 28.3% of cenobamate-treated and 8.8% of placebo-treated patients were seizure-free. Treatment-emergent adverse events reported in >10% in either group (cenobamate vs placebo) were somnolence (22.1% vs 11.9%), dizziness (22.1% vs 16.5%), headache (12.4% vs 12.8%), nausea (11.5% vs 4.6%), and fatigue (10.6% vs 6.4%).

Conclusion

Adjunctive treatment with cenobamate 200 mg/d significantly improved seizure control in adults with uncontrolled focal seizures and was well tolerated.

ClinicalTrials.gov identifier

NCT01397968.

Classification of evidence

This study provides Class I evidence that, for patients with uncontrolled focal seizures, adjunctive cenobamate reduces seizures.

Remarkably High Efficacy of Cenobamate in Adults With Focal-Onset Seizures: A Double-Blind, Randomized, Placebo-Controlled Trial

Safety and Efficacy of Adjunctive Cenobamate (YKP3089) in Patients With Uncontrolled Focal Seizures: A Multicentre, Double-Blind, Randomized, Placebo-Controlled, Dose-Responsive Trial

Krauss GL, Klein P, Brandt C, et al. Lancet Neurol. 2020;19(1):38-48. https://doi.org/10.1016/S1474-4422(19)30399-0.

BACKGROUND:

More than a third of patients with epilepsy are treatment resistant, and thus new, more effective therapies to achieve seizure freedom are needed. Cenobamate (YKP3089), an investigational antiepileptic drug, has shown broad-spectrum anticonvulsant activity in preclinical studies and seizure models. We aimed to evaluate the safety, efficacy, and tolerability of adjunctive cenobamate in patients with uncontrolled focal (partial)-onset epilepsy.

METHODS:

We did a multicenter, double-blind, randomized, placebo-controlled, dose–response study at 107 epilepsy and neurology centers in 16 countries. Adult patients (aged 18-70 years) with focal seizures despite treatment with 1 to 3 antiepileptic drugs were randomly assigned (1:1:1:1) via an interactive web response system, by block sizes of 4 within each country, to adjuvant once daily oral cenobamate at dose groups of 100 mg, 200 mg, or 400 mg, or placebo following an 8-week baseline assessment. Patients, investigators, and study personnel were masked to treatment assignment. The study included a 6-week titration phase and 12-week maintenance phase. The primary efficacy outcomes were percentage change in 28-day focal seizure frequency (focal aware motor, focal impaired awareness, or focal to bilateral tonic–clonic seizures) from baseline analyzed in the modified intention-to-treat population (≥1 dose and any postbaseline seizure data) and responder rates (≥50% reduction) analyzed in the maintenance phase population (≥1 dose in the maintenance phase and any maintenance phase seizure data). The primary efficacy outcomes were analyzed using a hierarchal step-down procedure comparing 200 mg versus placebo, 400 mg versus placebo, then 100 mg versus placebo. Safety and tolerability were compared descriptively across treatment groups for all randomized patients. This study is registered with ClinicalTrials.gov, number NCT01866111.

FINDINGS:

Between July 31, 2013, and June 22, 2015, 437 patients were randomly assigned to either placebo (n = 108) or cenobamate 100 mg (n = 108), 200 mg (n = 110), or 400 mg (n = 111). Of these patients, 434 (106 [98%] in placebo group, 108 [100%] in 100 mg group, 109 [99%] in 200 mg group, and 111 [100%] in 400 mg group) were included in the modified intention-to-treat population, and 397 (102 [94%] in placebo group, 102 [94%] in 100 mg group, 98 [89%] in 200 mg group, and 95 [86%] in 400 mg group) were included in the modified intention-to-treat maintenance phase population. Median percentage changes in seizure frequency were −24.0% (interquartile range: −45.0 to −7.0%) for the placebo group compared to −35.5% (−62.5 to −15.0%; P = .0071) for the 100 mg dose group, −55.0% (−73.0 to −23.0%; P < .0001) for the 200 mg dose group, and −55.0% (−85.0 to −28.0%; P < .0001) for the 400 mg dose group. Responder rates during the maintenance phase were 25% (26 of 102 patients) for the placebo group compared to 40% (41 of 102; odds ratio: 1.97, 95% confidence interval: 1.08-3.56; P = .0365) for the 100 mg dose group, 56% (55 of 98; 3.74, 2.06-6.80; P < .0001) for the 200 mg dose group, and 64% (61 of 95; 5.24, 2.84-9.67; P < .0001) for the 400 mg dose group. Treatment-emergent adverse events occurred in 76 (70%) of 108 patients in the placebo group, 70 (65%) of 108 in the 100 mg group, 84 (76%) of 110 in the 200 mg group, and 100 (90%) of 111 in the 400 mg group. Treatment-emergent adverse events led to discontinuation in 5 (5%) patients in the placebo group, 11 (10%) in the 100 mg dose group, 15 (14%) in the 200 mg dose group, and 22 (20%) in the 400 mg dose group. One serious case of drug reaction with eosinophilia and systemic symptoms occurred in the 200 mg cenobamate group. No deaths were reported.

INTERPRETATION:

Adjunctive cenobamate reduced focal (partial)-onset seizure frequency, in a dose-related fashion. Treatment-emergent adverse events were most frequent in the highest dose group. Cenobamate appears to be an effective treatment option in patients with uncontrolled focal seizures.