Cenobamate and Clobazam Combination as Personalized Medicine in Autoimmune-Associated Epilepsy With Anti-Gad65 Antibodies

Anti-GAD65 Antibodies Related Refractory Epilepsy Successfully Treated with Tocilizumab: A Case Report and Systematic Literature Review

Background

Although anti-GAD65 related epilepsy is rare, it needs more attention because it is refractory to the conventional therapies, has poor outcome and high relapse rate. In this study, we intended to report the efficacy of tocilizumab in the treatment of anti-GAD65 antibodies related refractory epilepsy based on our center's experience and literature review.

Methods

The clinical data of the patients managed with tocilizumab at Xiangya Hospital and those from the literature was collected and analysed.

Results

A female child presented at our center with neuropsychiatric symptoms and generalized tonic-clonic seizures (including status epilepticus) at the age of 3 years. She had positive anti-GAD65 autoantibodies. Her initial electroencephalograph showed multi-focal epileptic discharges and an early brain magnetic resonance imaging demonstrated increased intensity in the bilateral hippocampi and right insular cortex. She received several anti-seizures medications (ASMs) and immunotherapies without significant improvement; however, she experienced significant clinical, electrographic and radiological improvement after receiving four cycles of the tocilizumab. Literature review unveiled two more female cases. The mean age of seizure onset for three cases was 7.72 years, and they presented with refractory seizures (n=3), neuropsychiatric symptoms (n=3), ataxia (n=2), and anti-GAD autoantibodies were elevated in both the serum and cerebrospinal fluid (n=3). All three cases tried several combinations of ASMs and immunotherapies before tocilizumab but they remained with refractory epilepsy. Following several cycles of the tocilizumab, all cases had significant positive changes: seizure freedom (n=1), seizure control (n=2), improved-normal cognition (n=3), improved neuropsychiatry symptoms (n=2) and controlled ataxia (n=2).

Conclusion

Tocilizumab seems to be an effective therapy for the refractory anti-GAD65 related epilepsy as it can control seizures, improve cognition and neuropsychiatric symptoms.

Cenobamate add-on therapy for drug-resistant focal seizures: a systematic review and meta-analysis

INTRODUCTION

Cenobamate (CNB) is an anti-seizure medication (ASM) utilized for drug-resistant focal-onset seizures, which are difficult to manage with usual agents. Previous studies demonstrated that it can be effective in patients with refractory epilepsy.

METHODS

The MEDLINE, Cochrane, and Scopus databases were systematically searched up to 24 October 2024. A Random-effects model was employed to compute the Mean Difference (MD) and the Risk Ratio (RR) with 95% Confidence Intervals (CI). Statistical Analyses were performed utilizing RStudio 4.4.2.

RESULTS

Four studies were included, comprising 906 patients; 527 (59%) received CNB as add-on therapy. The results indicated that the 50% responder rate (RR 1.77; 95% CI: 1.28 to 2.44, p = 0.000551, I² = 70.3%) and seizure freedom (RR of 3.09; 95% CI: 1.91 to 5.00, p = 0.000004, I² = 8.7%) were significantly higher in this group.

CONCLUSIONS

In this meta-analysis of four studies, CNB as an add-on therapy significantly reduced seizure frequency in patients with uncontrolled focal seizures, making it a promising option for improved seizure control and quality of life.

Efficacy of add-on Cenobamate treatment in refractory epilepsy due to Rasmussen's encephalitis

OBJECTIVE

To assess antiseizure effects of cenobamate, a new antiseizure medication with at least two mechanisms of action, in the rare, highly pharmacoresistant and progressive epilepsy syndrome related to Rasmussen's encephalitis.

METHODS

Three patients from the epilepsy centers in Freiburg, Kork, and Valencia are reported with focal epilepsy which had been pharmacoresistant to more than 10 prior treatment regimens. Assessment included at least 1 year of follow-up after cenobamate introduction and included seizure frequency, seizure severity (in particular status epilepticus) and changes in co-medication.

RESULTS

In the three patients, cenobamate add on treatment proved superior to all prior antiseizure and immunomodulatory treatments which had been individually applied. Not only were focal to bilateral tonic-clonic seizure completely controlled, but also focal motor status epilepticus no longer occurred. Co-medication could be reduced in all patients.

SIGNIFICANCE

This case series in a rare and highly pharmacoresistant epilepsy syndrome suggests high efficacy of cenobamate add-on treatment for seizure control. This may be a valuable information in epilepsy related to Rasmussen encephalitis and calls for further elucidation of the mechanism involved in superior seizure control also compared to prior treatments including sodium channel blockers and benzodiazepines.

PLAIN LANGUAGE SUMMARY

Rasmussen's encephalitis is a rare type of epilepsy that gets worse over time and doesn't respond well to most seizure medications. We describe three patients who tried many treatments without much success, but when they added cenobamate to their treatment, it worked better than the other medications. This also let them lower the overall amount of medication they were taking.

Adjunctive cenobamate in people with focal onset seizures: Insights from the Italian Expanded Access Program

OBJECTIVE

This study was undertaken to assess the effectiveness/tolerability of adjunctive cenobamate, variations in the load of concomitant antiseizure medications (ASMs) and predictors of clinical response in people with focal epilepsy.

METHODS

This was a retrospective study at 21 centers participating in the Italian Expanded Access Program. Effectiveness outcomes included retention and responder rates (≥50% and 100% reduction in baseline seizure frequency). Tolerability/safety outcomes included the rate of treatment discontinuation due to adverse events (AEs) and their incidence. Total drug load was quantified as the number of concomitant ASMs and total defined daily dose (DDD). Concomitant ASMs were also classified according to their mechanism of action and pharmacokinetic interactions to perform explorative subgroup analyses.

RESULTS

A total of 236 subjects with a median age of 38 (Q1-Q3 = 27-49) years were included. At 12 months, cenobamate retention rate was 78.8% and responders were 57.5%. The seizure freedom rates during the preceding 3 months were 9.8%, 12.2%, 16.3%, and 14.0% at 3, 6, 9, and 12 months. A higher percentage of responders was observed among subjects treated with clobazam, although the difference was not statistically significant. A total of 223 AEs were recorded in 133 of 236 participants, leading to cenobamate discontinuation in 8.5% cases. At 12 months, a reduction of one or two concomitant ASMs occurred in 42.6% and 4.3% of the subjects. The median total DDD of all concomitant ASMs decreased from 3.34 (Q1-Q3 = 2.50-4.47) at baseline to 2.50 (Q1-Q3 = 1.67-3.50) at 12 months (p < .001, median percentage reduction = 22.2%). The highest rates of cotreatment withdrawal and reductions in the DDD were observed for sodium channel blockers and γ-aminobutyric acidergic modulators (above all for those linked to pharmacokinetic interactions), and perampanel.

SIGNIFICANCE

Adjunctive cenobamate was associated with a reduction in seizure frequency and in the burden of concomitant ASMs in adults with difficult-to-treat focal epilepsy. The type of ASM associated did not influence effectiveness except for a favorable trend with clobazam.

Autoimmune-associated seizure disorders

With the discovery of an expanding number of neural autoantibodies, autoimmune etiologies of seizures have been increasingly recognized. Clinical phenotypes have been identified in association with specific underlying antibodies, allowing an earlier diagnosis. These phenotypes include faciobrachial dystonic seizures with LGI1 encephalitis, neuropsychiatric presentations associated with movement disorders and seizures in NMDA-receptor encephalitis, and chronic temporal lobe epilepsy in GAD65 neurologic autoimmunity. Prompt recognition of these disorders is important, as some of them are highly responsive to immunotherapy. The response to immunotherapy is highest in patients with encephalitis secondary to antibodies targeting cell surface synaptic antigens. However, the response is less effective in conditions involving antibodies binding intracellular antigens or in Rasmussen syndrome, which are predominantly mediated by cytotoxic T-cell processes that are associated with irreversible cellular destruction. Autoimmune encephalitides also may have a paraneoplastic etiology, further emphasizing the importance of recognizing these disorders. Finally, autoimmune processes and responses to novel immunotherapies have been reported in new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES), warranting their inclusion in any current review of autoimmune-associated seizure disorders.

A Systematic Review of the Predictive and Diagnostic Uses of Neuroinflammation Biomarkers for Epileptogenesis

A central role for neuroinflammation in epileptogenesis has recently been suggested by several investigations. This systematic review explores the role of inflammatory mediators in epileptogenesis, its association with seizure severity, and its correlation with drug-resistant epilepsy (DRE). The study analysed articles published in JCR journals from 2019 to 2024. The search strategy comprised the MESH, free terms of "Neuroinflammation", and selective searches for the following single biomarkers that had previously been selected from the relevant literature: "High mobility group box 1/HMGB1", "Toll-Like-Receptor 4/TLR-4", "Interleukin-1/IL-1", "Interleukin-6/IL-6", "Transforming growth factor beta/TGF-β", and "Tumour necrosis factor-alpha/TNF-α". These queries were all combined with the MESH terms "Epileptogenesis" and "Epilepsy". We found 243 articles related to epileptogenesis and neuroinflammation, with 356 articles from selective searches by biomarker type. After eliminating duplicates, 324 articles were evaluated, with 272 excluded and 55 evaluated by the authors. A total of 21 articles were included in the qualitative evaluation, including 18 case-control studies, 2 case series, and 1 prospective study. As conclusion, this systematic review provides acceptable support for five biomarkers, including TNF-α and some of its soluble receptors (sTNFr2), HMGB1, TLR-4, CCL2 and IL-33. Certain receptors, cytokines, and chemokines are examples of neuroinflammation-related biomarkers that may be crucial for the early diagnosis of refractory epilepsy or may be connected to the control of epileptic seizures. Their value will be better defined by future studies.

Spanish consensus on the management of concomitant antiseizure medications when using cenobamate in adults with drug-resistant focal seizures

OBJECTIVE

Cenobamate is an antiseizure medication (ASM) associated with high rates of seizure freedom and acceptable tolerability in patients with focal seizures. To achieve the optimal cenobamate dose for maximal potential effectiveness while avoiding or minimizing drug-related adverse events (AEs), the administration of cenobamate with other ASMs must be managed through concomitant ASM load reduction. A panel of Spanish epilepsy experts aimed to provide a Spanish consensus on how to adjust the dose of concomitant ASMs in patients with drug-resistant epilepsy (DRE) in order to improve the effectiveness and tolerability of adjunctive cenobamate.

METHODS

A three-stage modified Delphi consensus process was undertaken, including six Spanish epileptologists with extensive experience using cenobamate. Based on current literature and their own expert opinion, the expert panel reached a consensus on when and how to adjust the dosage of concomitant ASMs during cenobamate titration.

RESULTS

The expert panel agreed that tailored titration and close follow-up are required to achieve the best efficacy and tolerability when initiating cenobamate in patients receiving concomitant ASMs. When concomitant clobazam, phenytoin, phenobarbital, and sodium channel blockers are taken at high dosages, or when the patient is receiving two or more sodium channel blockers, dosages should be proactively lowered during the cenobamate titration period. Other concomitant ASMs should be reduced only if the patient reports a moderate/severe AE at any stage of the titration period.

SIGNIFICANCE

Cenobamate is an effective ASM with a dose-dependent effect. To maximize effectiveness while maintaining the best tolerability profile, co-medication management is needed. The recommendations included herein provide practical guidance for proactive and reactive management of co-medication in cenobamate-treated patients with DRE and a high drug load.

PLAIN LANGUAGE SUMMARY

Patients with epilepsy may continue to have seizures even after treatment with several different antiseizure medications (ASMs). Cenobamate is an ASM that can reduce seizures in these patients. In this study, six Spanish experts in epilepsy discussed the best way to use cenobamate in drug-resistant epilepsy. They provide practical guidance on when and how the dose of other ASMs might be adjusted to reduce side effects and optimize the use of cenobamate.