Knupp, Kelly G.

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 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.

Abstract Objective Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterized by drug‐resistant seizures and developmental slowing. Although cognitive and executive function deficits have been described, their early trajectory is not well understood. Methods The prospective ENVISION natural history study (NCT04537832) assessed cognitive, executive, and adaptive function in children younger than 5 years of age with SCN1A + DS every 6 months for up to 2 years using Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID‐III), Wechsler Preschool & Primary Scale of Intelligence, 4th Edition (WPPSI‐IV), Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3), Behavior Rating Inventory of Executive Function – Preschool Version (BRIEF‐P), and Pediatric Evaluation of Disability Inventory (PEDI). Results Fifty‐eight children were enrolled, with 47% younger than age 2 years. At least 80% of children did not achieve age‐appropriate milestones. Mean BSID‐III Cognitive raw scores increased minimally, with age‐equivalent gains of only 3 months over 1.5 years. Mean Cognitive Composite scores declined significantly by Month 12 (from 81.6 to 72.2; change: –11.0, 95% confidence interval [CI]: −15.3 to −6.8), signaling a widening gap compared with neurotypical development. Executive function worsened, with mean BRIEF‐P Global Executive Composite T‐scores increasing by 3.2 points/year. For some participants, scores were 5 standard deviations (SD) above the normative mean, reflecting abilities profoundly below age expectations (bottom .00003% of the population). Adaptive functioning worsened, with mean VABS‐3 Adaptive Behavior Composite decreasing from 78.7 to 68.1 over 1.5 years (change: –9.0, 95% CI: −11.9 to −6.1) and greater decline among children <2 years at enrollment, with scores decreasing by ~15 points (1 SD). Over half of children >3 years could not remove clothing independently; and when placed on a toilet, 48% could not use it. Significance Infants and young children with SCN1A + DS show significant and progressive developmental slowing across several domains, highlighting urgent need for therapies to mitigate the devastating impact on individuals and families.

Abstract Objective This study was undertaken to evaluate the response to second treatments for infantile epileptic spasms syndrome (IESS). Methods Infants aged 2–24 months with IESS were prospectively enrolled in the National Infantile Spasms Cohort study at 21 pediatric epilepsy centers in the United States from 2012 to 2018. We analyzed data from infants who initially received standard treatment (hormonal therapy [adrenocorticotropic hormone, high‐dose prednisolone] or vigabatrin), had continued or recurring epileptic spasms, and received a second treatment. We excluded those with tuberous sclerosis. Treatment groups included hormonal therapy followed by vigabatrin (reference), hormonal‐to‐hormonal, hormonal‐to‐nonstandard, vigabatrin‐to‐hormonal, and vigabatrin‐to‐nonstandard. Nonstandard treatments included other antiseizure medications and dietary therapy. Treatment groups were tested for differences in 3‐month clinical remission using a binary logistic regression to estimate odds ratios (ORs). Results There were 153 infants with IESS who received second treatments. The highest rates of 3‐month remission were among infants in the hormonal‐to‐vigabatrin (22/65, 34%) and vigabatrin‐to‐hormonal (9/26, 35%) groups, followed by vigabatrin‐to‐nonstandard (3/10, 30%), hormonal‐to‐hormonal (4/22, 18%), and hormonal‐to‐nonstandard (1/30, 3.3%). Compared to the hormonal‐to‐vigabatrin group (reference), fewer infants had remission in the hormonal‐to‐nonstandard group (OR = .07, 95% confidence interval [CI] = .01–.53), and there was a trend toward fewer infants in the hormonal‐to‐hormonal group (OR = .43, 95% CI = .13–1.4, p = .17). Following initial hormonal treatment, the number needed to treat was three infants for one additional infant to have remission when treated with vigabatrin compared to nonstandard therapy as the second treatment. Significance This updated analysis with an expanded sample size provided power for additional subgroup analysis. Overall response rates were low, and at best only one third had remission after second treatment. Results support a clinical strategy of switching mechanism of action when selecting a second medication for epileptic spasms (i.e., use vigabatrin after hormonal therapy, or hormonal therapy after vigabatrin). Our findings also support the use of standard over nonstandard therapies.