Wirrell, Elaine C

Abstract Objective To assess the efficacy and safety of fenfluramine in patients with Dravet syndrome (DS) stratified by age, number of previously attempted antiseizure medications (ASMs), and SCN1A pathogenic variant status. Methods In this post hoc analysis, data from three randomized controlled trials (RCTs) in patients with DS (2–18 years) were pooled and stratified by age (<4; ≥4 years), number of previous ASMs (1–3; 4–6; ≥7), and SCN1A pathogenic variant status ( SCN1A +; SCN1A −). Stratified groups were assessed and compared with the pooled placebo group (change in monthly convulsive seizure frequency [MCSF], longest convulsive seizure‐free interval, and Clinical Global Impression–Improvement [CGI–I] scale scores rated by parents/caregivers and investigators), and safety (treatment‐emergent adverse events [TEAEs]: frequency, days to onset, and proportion resolved). Results Among 348 patients included in the RCTs, 216 were randomized to fenfluramine (0.7 mg/kg/day, n = 88; 0.4 mg/kg/day [with stiripentol], n = 43; 0.2 mg/kg/day, n = 85) and 132 to placebo. Compared with placebo, fenfluramine treatment (all doses combined) resulted in greater MCSF reductions, greater increases in longest convulsive seizure‐free intervals, and a higher proportion of parents/caregivers and investigators reporting clinically meaningful improvement (“Much Improved”, “Very Much Improved”) on CGI–I scores across all stratified groups. CGI–I scores were consistent across fenfluramine doses in most stratified groups, but patients with the fewest number of previous ASMs had the greatest frequency of clinically meaningful improvement on investigator‐rated CGI–I scores. Safety outcomes were similar across all strata. Most TEAEs resolved by end‐of‐study. Significance Fenfluramine treatment was associated with improved seizure outcomes and global functioning compared with placebo regardless of age, number of previous ASMs, and SCN1A status in patients with DS. Fenfluramine was well‐tolerated; no new safety signals were identified. Further studies with larger sample sizes (including adults) and a priori inferential analyses of stratified groups are warranted. Plain Language Summary Patients with Dravet syndrome struggle with seizures and everyday life. In three studies, patients aged 2–18 years received fenfluramine or placebo (sugar pill). Fenfluramine lowered seizures without many side effects. Researchers combined results from these studies to see how fenfluramine worked in different patient groups based on age, number of previous medications, and a gene called SCN1A . They looked at seizure reduction and whether doctors felt patients had improved. In all groups, fenfluramine worked better than placebo, with similar side effects. Researchers believe fenfluramine helped these patients, but some groups were small, so these results need to be confirmed.

ABSTRACT Objectives Dravet syndrome (DS) is a severe, drug‐resistant developmental and epileptic encephalopathy (DEE) that requires polytherapy for adequate seizure control. The need to combine multiple antiseizure medications (ASMs), together with variability in seizure types, safety considerations, and evolving patient needs, makes treatment optimization particularly complex for clinicians. As the United States (US) has one of the largest populations of DS patients and pediatric neurologists/epileptologists worldwide, this study aimed to develop US‐focused consensus guidance to guide clinicians in managing treatment combinations in DS. Methods A modified Delphi consensus methodology was applied. 35 statements tailored to the US clinical context were developed, covering six key themes: general treatment principles; strategies to support and empower caregivers; stiripentol (STP) as an add‐on to DS‐specific and nonspecific ASMs; use of fenfluramine (FFA) in STP‐containing regimens; use of cannabidiol (CBD) in STP‐containing regimens; and patient follow‐up during treatment initiation. Statements were submitted for online voting to 52 US clinicians with expertise in DS and experience with all approved DS‐specific ASMs. Agreement was rated using a 9‐point Likert scale, with predefined criteria used to determine strong, good, or absent consensus. Results 26 experts participated in the voting process. Of the 35 statements evaluated, 23 (66%) reached strong consensus, 6 (17%) reached good consensus, and 6 (17%) did not reach consensus. Strong agreement was observed for general principles of DS management, caregiver involvement, structured follow‐up, and several practical aspects of initiating and managing STP‐ and FFA‐containing regimens. Areas without consensus primarily concerned CBD efficacy expectations, dosing strategies, and pharmacokinetic interactions in complex polytherapy regimens. Significance This US‐focused consensus provides structured guidance to support clinical decision‐making in the management of polytherapy for DS. Plain language summary Dravet syndrome is a rare and severe form of epilepsy that begins in early childhood and causes seizures that are difficult to control and often persist throughout life. Because most patients require treatment with multiple medications, managing Dravet syndrome is complex and must adapt as patients grow and their needs change. This US‐focused consensus brings together published evidence and expert clinical experience to provide practical guidance on the management of polytherapy in Dravet syndrome, supporting clinicians in optimizing patient care.

Abstract This article summarizes data for 13 investigational treatments for which at least preliminary seizure outcome data in patients with epilepsy were reported at the Eighteenth Eilat Conference on New Antiepileptic Drugs and Devices held in Madrid, Spain, on May 3–6, 2026. The treatments reviewed include bexicaserin, a selective 5‐hydroxytryptamine (5‐HT, serotonin) type 2C (5‐HT 2C ) receptor superagonist investigated as a treatment for developmental and epileptic encephalopathies (DEEs); BMB‐101, a selective 5‐HT 2C receptor agonist investigated for the treatment of absence seizures and DEEs; elsunersen, an antisense oligonucleotide designed for the treatment of early‐onset SCN2A ‐DEE; EPX‐100 (clemizole hydrochloride), an antihistamine endowed with agonist activity at 5‐HT 2A and 5‐HT 2B receptors, repurposed as a treatment for DEEs; ES‐481, an antagonist of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptors containing the transmembrane AMPA receptor regulatory protein γ8 (TARP‐γ8), under investigation for the treatment of drug‐resistant epilepsy; ETX‐101, a gene therapy in development for the treatment of SCN1A ‐positive Dravet syndrome; PrevEp‐006 (intranasal seletracetam), a synaptic vesicle glycoprotein 2A (SV2A) ligand under investigation as an acute seizure rescue therapy; radiprodil, a negative allosteric modulator that binds to the GluN2B subunit of the N ‐methyl‐ D ‐aspartate (NMDA) receptor, in development for the treatment of seizures and other symptoms associated with GRIN‐related neurodevelopmental disorder, tuberous sclerosis complex, and focal cortical dysplasia type II; RAP‐219, a selective negative allosteric modulator of TARP‐γ8, in development for drug‐resistant focal epilepsy; relutrigine, a selective disease‐state sodium channel modulator investigated as a treatment for SCN2A ‐ and SCN8A ‐DEE; Staccato Alprazolam, a breath‐actuated device that delivers alprazolam to the lungs for rapid seizure termination; vormatrigine, a functionally selective sodium channel modulator in development for the treatment of focal seizures; and zorevunersen, an antisense oligonucleotide engineered to restore endogenous Nav1.1 protein expression, investigated for the treatment of Dravet syndrome. Overall, the evidence reviewed justifies expectations for improved health outcomes for the millions of children and adults with epilepsy who do not fully benefit from existing therapies.

Abstract Over the last 34 years, the Eilat Conference on New Antiepileptic Drugs and Devices has provided an interactive forum for stakeholders to discuss investigational and recently licensed treatments for seizures and epilepsy. The Eighteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVIII) took place in Madrid, Spain, on May 3–6, 2026. This article provides summaries of eight treatments in preclinical and early clinical development that were presented at EILAT XVIII. These include AUT00206, a positive allosteric modulator of Kv3.1 and Kv3.2 voltage‐gated potassium channels in development for the treatment of rare epilepsy syndromes as well as neurodevelopmental and neuropsychiatric disorders; ION283, an antisense oligonucleotide designed to suppress the expression of glycogen synthase 1, under investigation for the treatment of Lafora disease; MSCA‐7136, a selective allosteric RAS/mitogen‐activated protein kinase—extracellular signal regulated kinase (MEK) inhibitor being developed for the treatment of focal seizures associated with mesial temporal lobe epilepsy and seizures associated with tuberous sclerosis complex; OV329, a selective inhibitor of γ‐aminobutyric acid (GABA) aminotransferase, in development for the treatment of drug‐resistant focal seizures; PTI5803 (probenecid), an uricosuric agent and a blocker of pannexin 1 channels, repurposed as a treatment for seizures associated with focal cortical dysplasia; simufilam, a filamin A modulator under investigation for the treatment of tuberous sclerosis complex‐related epilepsy; SN‐2000, a selective allosteric phosphodiesterase 4B inhibitor, in development for the treatment of focal seizures; and sodium selenate, a promoter of the dephosphorylation of pathological hyperphosphorylated tau in the brain, under investigation as a disease‐modifying agent in mesial temporal lobe epilepsy. Treatments in more advanced clinical development are discussed in an accompanying article.

Abstract Objective Invasive presurgical evaluation plays a key role in pediatric epilepsy surgery, particularly in magnetic resonance imaging (MRI)‐negative cases, by guiding resective, disconnective, or ablative procedures. This International League Against Epilepsy (ILAE) Pediatric Epilepsy Surgery Taskforce study provides an updated global overview of current invasive evaluation practices. Methods Group‐level data were collected from 61 epilepsy surgery programs (49 pediatric‐only) in 29 countries across six continents. Included were children and adolescents who underwent presurgical evaluation and epilepsy surgery in 2023. The study was designed to enable comparison with the similar ILAE survey conducted in 2004. Results A total of 2427 patients were included. Invasive evaluations were performed in 21.1% of cases, most frequently in North America (33.7%, higher than Europe: 18.0%, p = .003). Among invasive cases, 32.3% had no detectable MRI abnormalities. The main indication for invasive evaluation was seizure onset localization (88.1%), followed by motor or sensory mapping (17.2%) and language mapping (14.2%). Stereoelectroencephalography (SEEG) was the predominant technique (19.8% overall, 93.6% of invasive cases), more common in North America (30.0%, p = .021) and less common in South America (7.4%, p < .001). Subdural electrodes were used in only 3.2% of invasive cases, and combined depth and subdural approaches in 3.2%. SEEG‐guided radiofrequency thermocoagulation (RF‐TC) was performed in 40.9% of SEEG cases, most commonly in Asia (63.8%). In 16.2% of invasive evaluations, patients did not proceed to resection, disconnection, or ablation, with the highest rate in Europe (28.5%). Significance This global survey provides the first broad overview of invasive evaluation practices in pediatric epilepsy surgery across participating centers worldwide. It highlights the widespread adoption of SEEG, declining use of subdural electrodes, and increasing application of SEEG‐guided RF‐TC. The high proportion of MRI‐negative cases and the considerable proportion of patients not proceeding to resection, disconnection, or ablation underscore the complexity of contemporary surgical candidates and the need for further refinement of selection strategies.

Abstract Objective Pediatric epilepsy surgery is well established, but contemporary global data on referral and presurgical evaluation practices are lacking. This International League Against Epilepsy (ILAE) Pediatric Epilepsy Surgery Task Force study provides an updated overview of current trends and regional differences. Methods Group‐level data were collected from 61 epilepsy surgery programs (49 pediatric‐only) across 29 countries and six continents, identified through ILAE networks, and included all children and adolescents treated in 2023 who underwent presurgical evaluation/epilepsy surgery. Results Group‐level data were available for 2427 patients. Mean age at surgery was 9.1 ± 4.9 years; mean epilepsy duration was 5.3. At surgery, 3.2% were <1 year old (highest in Oceania: 5.1%), and 6.1% were nonpharmacoresistant (highest in Europe: 15.0%). Prior neurosurgery was reported in 14.2% (highest in North America: 28.8%), including 8.0% resections (6.1% for epilepsy, 1.5% for tumors; highest in Oceania: 16.5%), 2.3% disconnections (1.3% corpus callosotomy; highest in South America: 4.7%), and 4.2% neuromodulation (3.7% vagal nerve stimulation, .2% responsive neurostimulation, one deep brain stimulation; highest in North America: 12.2%). Developmental and epileptic encephalopathies (DEEs) at surgery included Lennox–Gastaut syndrome (7.4%), infantile epileptic spasms syndrome (5.1%), and DEE with spike–wave activation in sleep (1.5%). Presurgical investigations included fluorodeoxyglucose positron emission tomography (52.6%; highest in Oceania: 79.7%), genetic testing (46.8%; highest in Asia: 54.3%), magnetic resonance imaging (MRI) postprocessing (32.4%; highest in South America: 53.0%), functional MRI (fMRI; 15.2%; highest in North America: 40.3%), magnetoencephalography (11.9%; highest in North America: 39.3%), single photon emission computed tomography (9.6%; highest in North America: 22.2%), high‐density electroencephalography (EEG; 1.9%; highest in Europe: 4.7%), source localization (1.6%; highest in Oceania: 7.6%), Wada test (1.2%; highest in North America: 3.5%), and EEG‐fMRI (.5%; highest in Europe: 1.1%). Significance Despite some early surgeries, including in infancy and before pharmacoresistance, mean epilepsy duration before surgery remains >5 years. Reoperations are common, with resection more frequent than neuromodulation. Genetic testing in nearly half of patients reflects its growing relevance, and the high rate of DEEs underscores the complexity of surgical candidates.

Abstract Aims To compare the prevalence of autism spectrum disorder (ASD) in children with and without epilepsy using clinical diagnoses and chart review with research‐defined criteria and to examine sex ratios, age at ASD onset, and intellectual disability between groups. Method The Olmsted County birth cohort included 30 490 individuals, of whom 257 (0.84%) had epilepsy diagnosed before 19 years of age. The cohort was previously screened for ASD using three case definitions: research‐inclusive (ASD‐R I ), research‐narrow (ASD‐R N ), and clinically diagnosed ASD (ASD‐C). For those with ASD‐R I , we assessed sex, intellectual disability (IQ < 70), and age at ASD onset. Means and proportions are reported when available. Results ASD prevalence was significantly higher in participants with epilepsy across all definitions: ASD‐R I 21.4% versus 3.2%; ASD‐R N 14.0% versus 1.6%; and ASD‐C 7.9% versus 0.7%. Children with both epilepsy and ASD‐R I were more often female (38.2% vs 25.8%), had higher rates of intellectual disability (56.5% vs 15.4%), and met the ASD‐R I criteria at a younger age (mean 7 years 5 months vs 8 years 8 months). Interpretation Co‐occurring ASD and epilepsy are frequently associated with intellectual disability, earlier age at ASD diagnosis, and reduced male predominance.

Abstract Objectives Dravet syndrome (DS) is a drug‐resistant developmental and epileptic encephalopathy, often requiring three or more antiseizure medications (ASMs). Consequently, the therapeutic landscape is highly complex, combining DS‐specific agents (stiripentol, STP; cannabidiol, CBD; fenfluramine, FFA), non‐specific ASMs, and non‐pharmacologic options such as dietary therapy or neuromodulation. In addition, recognition of patients' changing needs across the lifespan, together with the essential contribution of caregiver education to effective treatment oversight—including awareness of potential drug–drug interactions and adverse events—emphasizes the value of an integrated and forward‐looking approach. A consensus initiative was developed to guide clinicians in the management of patients with DS, with a particular focus on STP‐containing regimens. Methods Based on a literature review and clinical vignette discussions, a nominal group of five international DS experts developed 38 statements across six themes: (i) general principles, (ii) guiding physicians to empower families, (iii) STP as add‐on to specific and non‐specific Dravet ASMs, (iv) FFA in regimens containing STP, (v) CBD in regimens containing STP, and (vi) patient follow‐up during treatment initiation. Statements were scored on a 9‐point Likert scale (1 = strongly disagree, 9 = strongly agree) first by the nominal group and then by an international panel of 59 DS clinicians. Consensus was defined as ≥75% rating ≥7 and/or a median ≥8. Results Thirty‐four of the 38 statements (89%) reached consensus among both the nominal group and the international panel; one did not reach consensus in either, and three reached consensus only among the nominal group. Both panels agreed on the importance of involving families in treatment decisions and follow‐up, as well as on key aspects of polytherapy management, including ASM initiation, treatment adjustments, and adverse event management. Significance This international consensus integrates evidence and clinical expertise to establish shared principles that address a long‐standing gap in the polytherapeutic management of Dravet syndrome. Plain Language Summary Dravet syndrome is a rare and severe form of epilepsy that begins in early childhood, with seizures that often persist throughout life. Because the disease is highly drug resistant, most patients are treated with polytherapy, making clinical management complex for clinicians. This consensus brings together published evidence and expert experience to provide practical guidance on the management of polytherapy in Dravet syndrome, supporting clinicians in optimizing patient care.

Abstract Objective Dravet syndrome (DS) is the prototypic developmental and epileptic encephalopathy, characterized by drug‐resistant seizures, developmental slowing, and many other morbidities. Detailed characterization of behavioral phenotypes and social–emotional skill development are limited. Methods We prospectively assessed behavioral and social–emotional problems in the ENVISION natural history study (NCT04537832) of children with DS associated with SCN1A pathogenic variants ( SCN1A + DS) enrolled at <5 years of age. Assessments every 3 months for up to 2 years included the Child Behavior Checklist (CBCL), Strengths and Difficulties Questionnaire (SDQ), Brief Infant‐Toddler Social and Emotional Assessment (BITSEA), and Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3). Results Fifty‐eight children with DS enrolled at 16 sites worldwide. Problematic behaviors—inattention, aggressive or oppositional behaviors, and withdrawn and autistic behaviors—began before age 3 years, became more evident with age, and were clinically significant in many children by age 3–4 years. CBCL Total, Externalizing, and Internalizing Problems T‐scores rose by approximately 3 points per year, and BITSEA Problem scale scores increased by 2.3 points annually ( p = .002). SDQ Hyperactivity scores worsened over time ( p = .013), whereas emotional difficulties remained stable. VABS‐3 Socialization domain scores, which were already more than 1 SD below the normative mean at baseline, decreased further, particularly in younger participants. Correlation analyses showed that poorer communication abilities were associated with increased problematic behaviors ( R = −.55 for CBCL Total Problems and VABS‐3 Communication scores). Mixed‐effects modeling identified age as the strongest predictor of worsening behavioral outcomes. Significance We found that behavioral and social–emotional problems are inherent components of DS that present in toddlerhood and worsen throughout early childhood. This highlights the need to diagnose and manage these issues early. Targeted therapy may alleviate the wide‐ranging morbidities that are intrinsic to DS, including the social–emotional and behavior problems that frequently emerge.