An examination of the efficacy and safety of fenfluramine in adults, children, and adolescents with Dravet syndrome in a real-world practice setting: A report from the Fenfluramine European Early Access Program

Fenfluramine treatment in pediatric patients with Dravet syndrome reduces seizure burden and overall healthcare costs: A retrospective and observational real-world study

OBJECTIVES

Dravet syndrome is a developmental and epileptic encephalopathy characterized by early onset epilepsy with multiple seizure types often intractable to treatment. Randomized clinical trials have demonstrated how treatment with fenfluramine significantly reduces seizure frequency in patients with Dravet syndrome. The study aims to (1) describe the efficacy and tolerability of fenfluramine in a Danish cohort of patients with Dravet syndrome; and (2) evaluate whether treatment with fenfluramine reduces epilepsy-related hospital contacts administrated by pediatricians or epilepsy-trained nurses.

METHODS

A retrospective registry-based cohort study at the Danish Epilepsy Centre, Filadelfia, Dianalund, Denmark, enrolled 30 pediatric patients with Dravet syndrome treated with fenfluramine between 2017 and 2023.

RESULTS

Thirty patients with Dravet syndrome (aged 3-21 years, 12 females) with a verified pathogenic SCN1A variant were included. They were treated with fenfluramine at a mean duration of 29 months with a mean maintenance dose of 0.5 mg/kg/day. The number of patient-years on treatment was 75 years. At last follow-up, 6 patients had discontinued treatment due to lack of efficacy or adverse effects. In the remaining 24 patients, generalized tonic-clonic seizures were reduced by ≥30% in 83%, by ≥50% in 67%, and by 100% in 25%. Additionally, 71% of the patients were reduced in concomitant anti-seizure medication, and 75% experienced a reduction (mean reduction at 52%, range 11%-94%) in epilepsy-related hospital contacts from baseline to the end of the treatment period.

SIGNIFICANCE

Treatment with fenfluramine effectively reduced seizure frequency and concomitant antiseizure medication in patients with Dravet syndrome. Furthermore, a decrease in epilepsy-related contacts by 80% was observed over 6 years of treatment, which may indicate cost-effective benefits.

PLAIN LANGUAGE SUMMARY

Patients with Dravet syndrome suffer from severe epileptic seizures that are difficult to treat with medication. Earlier, treatment with fenfluramine (an anti-seizure medication) has been documented to decrease the total number of seizures in patients with Dravet syndrome. This publication summarizes the experiences with fenfluramine in children with Dravet syndrome at the Danish Epilepsy Centre, Filadelfia, Dianalund, Denmark. Our publication also illustrates that treatment with fenfluramine may reduce the patients' number of yearly contacts with doctors and nurses specialized in epilepsy treatment, which may indicate cost-effectiveness.

Comprehensive scoping review of fenfluramine's role in managing generalized tonic-clonic seizures in developmental and epileptic encephalopathies

Developmental and epileptic encephalopathies (DEEs) are characterized by pharmacoresistant seizures and developmental delay. Patients with DEEs experience multiple seizure types, including tonic-clonic seizures (TCS) that can be generalized tonic-clonic (GTCS) or focal evolving to bilateral tonic-clonic (FBTCS). Fenfluramine (FFA) has demonstrated efficacy in reduction of TCS in patients with Dravet syndrome (DS), Lennox-Gastaut syndrome (LGS), and other DEEs. Using the PRISMA-ScR (Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Review) guidelines, we performed a scoping review to describe changes in TCS in patients treated with FFA. A comprehensive search of five literature databases was conducted up to February 14, 2023. Studies were included if they reported change in GTCS or TCS (but not FBTCS) after treatment with FFA in patients with DEEs. Duplicate patients and studies with unclear efficacy data were excluded. Fourteen of 422 studies met the eligibility criteria. Data extracted and evaluated by expert clinicians identified 421 unique patients with DS (in nine studies), CDKL5 deficiency disorder, SCN8A-related disorder, LGS, SCN1B-related disorder, and other DEEs. The median percent reduction in GTCS or TCS from baseline was available in 10 studies (n = 328) and ranged from 47.2% to 100%. Following FFA treatment, 10 studies (n = 144) reported ≥50% reduction in GTCS or TCS from baseline in 72% of patients; in nine of those (n = 112), 54% and 29% of patients achieved ≥75% and 100% reduction in GTCS or TCS from baseline, respectively. Overall, this analysis highlighted improvements in GTCS or TCS frequency when patients were treated with FFA regardless of the DEE evaluated. Future studies may confirm the impact of FFA on TCS reduction and on decreased premature mortality risk (including sudden unexpected death in epilepsy), improvement in comorbidities and everyday executive function, decreased health care costs, and improvement in quality of life.

Innovative LC-MS/MS method for therapeutic drug monitoring of fenfluramine and cannabidiol in the plasma of pediatric patients with epilepsy

We present a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying fenfluramine (FFA), its active metabolite norfenfluramine (norFFA), and Epidyolex®, a pure cannabidiol (CBD) oral solution in plasma. Recently approved by the EMA for the adjunctive treatment of refractory seizures in patients with Dravet and Lennox-Gastaut syndromes aged above 2 years, FFA and CBD still do not have established therapeutic blood ranges, and thus need careful drug monitoring to manage potential pharmacokinetic and pharmacodynamic interactions. Our method, validated by ICH guidelines M10, utilizes a rapid extraction protocol from 100 µL of human plasma and a reversed-phase C-18 HPLC column, with deuterated internal standards. The Thermofisher Quantiva triple-quadrupole MS coupled with an Ultimate 3000 UHPLC allowed multiple reaction monitoring detection, ensuring precise analyte quantification. The assay exhibited linear responses across a broad spectrum of concentrations: ranging from 1.64 to 1000 ng/mL for both FFA and CBD, and from 0.82 to 500 ng/mL for norFFA. The method proves accurate and reproducible, free from matrix effect. Additionally, FFA stability in plasma at 4 °C and -20 °C for up to 7 days bolsters its clinical applicability. Plasma concentrations detected in patients samples, expressed as mean ± standard deviation, were 0.36 ± 0.09 ng/mL for FFA, 19.67 ± 1.22 ng/mL for norFFA. This method stands as a robust tool for therapeutic drug monitoring (TDM) of FFA and CBD, offering significant utility in assessing drug-drug interactions in co-treated patients, thus contributing to optimized patient care in complex therapeutic scenarios.

New epilepsy therapies in development

Epilepsy is a common brain disorder, characterized by spontaneous recurrent seizures, with associated neuropsychiatric and cognitive comorbidities and increased mortality. Although people at risk can often be identified, interventions to prevent the development of the disorder are not available. Moreover, in at least 30% of patients, epilepsy cannot be controlled by current antiseizure medications (ASMs). As a result of considerable progress in epilepsy genetics and the development of novel disease models, drug screening technologies and innovative therapeutic modalities over the past 10 years, more than 200 novel epilepsy therapies are currently in the preclinical or clinical pipeline, including many treatments that act by new mechanisms. Assisted by diagnostic and predictive biomarkers, the treatment of epilepsy is undergoing paradigm shifts from symptom-only ASMs to disease prevention, and from broad trial-and-error treatments for seizures in general to mechanism-based treatments for specific epilepsy syndromes. In this Review, we assess recent progress in ASM development and outline future directions for the development of new therapies for the treatment and prevention of epilepsy.

Practical considerations for the use of fenfluramine to manage patients with Dravet syndrome or Lennox-Gastaut syndrome in clinical practice

Fenfluramine (FFA), an antiseizure medication (ASM) with serotonergic and sigma-1 receptor activity, is used to manage patients with developmental and epileptic encephalopathies (DEEs). It is approved in the US for treating seizures associated with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) in patients ≥2 years old and as add-on therapy for seizures associated with DS and LGS in the EU, UK, and Japan in similarly aged patients. Consensus guidelines for treatment of DS have recommended FFA to be an early-line ASM, and it has also shown efficacy in managing seizures associated with LGS. DS and LGS are DEEs associated with a range of seizure types, developmental impairments, and multiple comorbidities. Here we provide case vignettes describing 4 patients (3 DS and 1 LGS) aged 4-29 years old in whom up to 14 ASMs had previously failed, to illustrate real-world practice issues encountered by neurologists. This review provides guidance on the use of FFA in the context of ASM polytherapy and drug-drug interactions (DDIs), behavioral issues, dose titration, and adverse events. Along with data from the clinical trial program, these case vignettes emphasize the low risk of DDIs, a generally well-tolerated safety profile, and other seizure and nonseizure benefits (eg, improved cognition and sleep) associated with the use of FFA in DS or LGS. PLAIN LANGUAGE SUMMARY: Fenfluramine is used to treat seizures in individuals with Dravet syndrome and Lennox-Gastaut syndrome, but there are a range of issues that clinicians may face when treating patients. This review highlights four patients from the authors' everyday clinical work and offers guidance and practical considerations by neurologists with expertise in managing these complex conditions related to drug interactions, dosing, and side effects associated with fenfluramine.

Health care concerns in parents of children with different genetic developmental and epileptic encephalopathies: A qualitative study

AIM

To describe the experiences and unmet medical care needs of a group of parents of children with developmental and epileptic encephalopathies (DEEs) caused by the SCN1A, KCNQ2, CDKL5, PCDH19, and GNAO1 variants.

METHOD

A qualitative descriptive study was conducted. Participants were recruited using purposeful sampling. The inclusion criteria consisted of parents of children with DEEs caused by the SCN1A, KCNQ2, CDKL5, PCDH19, or GNAO1 variants, aged between 4 and 10 years old. In total, 21 parents were included. Data were acquired via researcher field notes and in-depth interviews. A thematic analysis was performed.

RESULTS

Three main themes were identified: (1) managing symptoms: epileptic seizures are experienced with great uncertainty and are accompanied by cognitive, behavioural, and motor symptoms; (2) accepting treatment: the ideal medication regimen is a challenge and the decision to withdraw or start a new therapy falls on the parents; and (3) therapeutic relationship and medical care: behaviours related to the health professional can hinder the therapeutic relationship with the parents. Parents are apprehensive about going to the emergency department.

INTERPRETATION

Professionals in emergency departments should acquire better knowledge of DEEs, welcome parents, and improve treatment for the children. The results of this study can serve as a starting point for a roadmap of relevant caregiver-reported outcomes in DEEs, to be implemented with new clinical trials and aetiology-targeted therapies.

WHAT THIS PAPER ADDS

Epileptic seizures are the symptom that is most experienced and feared by parents. The medication regime has no defined protocol and the decision to withdraw a medication is frequently left to parents.

Preocupaciones sobre la atención sanitaria en progenitores de niños con diferentes encefalopatías epilépticas genéticas del desarrollo: Un estudio cualitativo

Objetivo

Describir las experiencias y las necesidades de atención médica de un grupo de progenitores de niños con encefalopatías epilépticas y del desarrollo (EED) causadas por las variantes SCN1A, KCNQ2, CDKL5, PCDH19 y GNAO1.

Método

Se realizó un estudio cualitativo descriptivo. Los participantes fueron reclutados mediante un muestreo intencional. Los criterios de inclusión consistieron en progenitores de niños con EED causadas por las variantes SCN1A, KCNQ2, CDKL5, PCDH19 o GNAO1, con edades comprendidas entre los 4 y los 10 años. En total, se incluyeron 21 progenitores. Los datos se obtuvieron mediante entrevistas en profundidad y notas de campo del investigador. Se realizó un análisis temático.

Resultados

Se identificaron tres temas principales: (1) Manejando los síntomas, las crisis epilépticas se viven con gran incertidumbre, y se acompañan de síntomas cognitivos, conductuales y motores que limitan la vida del niño; b) Aceptando el tratamiento, la pauta de la medicación idónea es un reto, la decisión de retirar o comenzar una nueva terapia recae en los progenitores; y c) Relación terapéutica y atención médica, existen comportamientos y acciones del profesional que facilitan o dificultan la relación terapéutica con los progenitores. Acudir al servicio de urgencias es vivido con recelo por los progenitores.

Interpretación

Los profesionales de los servicios de urgencias deben conocer mejor las EED, acoger a los progenitores y mejorar el tratamiento de los niños. Los resultados de este estudio pueden servir como punto de partida para una hoja de ruta de los resultados relevantes reportados por los cuidadores de las EED, a implementar nuevos ensayos clínicos y terapias dirigidas a la etiología.

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Fenfluramine below the age of 2 years in Dravet syndrome: What about safety and efficacy?

Dravet syndrome (DS) is a rare developmental and epileptic encephalopathy. Infants with DS are especially vulnerable to the detrimental effects of prolonged and frequent seizures on development. Fenfluramine (FFA) is approved for the treatment of DS in patients aged 2 years and older. This study aims to evaluate the safety and efficacy of FFA in patients with DS younger than 2 years. We analyzed safety, tolerability, seizure, and neuropsychological outcome in a real-world setting. Developmental profile was investigated using Griffiths Mental Development Scales (GMDS). Five patients received FFA at a mean age of 14.9 months (9.6-18.6). Median follow-up was 13 months (interquartile range [IQR] = 12.9-24.4). All patients showed good tolerance to FFA. No significant variation of body mass index or echocardiographic issue was observed. Monthly median convulsive seizure frequency (MCSF) was 1.71 (IQR = 1.56-3.27) at the 6-month baseline period and .92 (IQR = .43-1.28) at last follow-up, with a median 54.43 (IQR = 40.91-60.83) percentage reduction in MCSF. Two of five patients had a performance improvement on GMDS subscales. Overall, the use of FFA below the age of 2 years in our small sample of patients was safe and represents a promising opportunity for seizure control and for protection of the neurodevelopmental outcome.

What have we learned from the real-world efficacy of FFA in DS and LGS? A post-marketing study in clinical practice

OBJECTIVE

To evaluate the effectiveness and tolerability of fenfluramine (FFA) in routine clinical practice treating real-world populations with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS).

METHODS

This was a retrospective analysis of patients with DS or LGS who initiated FFA treatment from 2018 to 2022 at a single center. Patient demographics, medical history, seizure characteristics, and treatment outcomes were collected from electronic medical records. Duration of FFA treatment, dosage regimens, seizure frequency, seizure severity, improvements in cognitive, social, and motor outcomes, and adverse events were extracted and analyzed. Effectiveness was assessed using ≥50 % sustained reduction in monthly seizure frequency vs baseline for ≥2 consecutive months at 12 months; seizure freedom was a secondary measure.

RESULTS

Seizure frequency data was available for 56 of 68 patients included in the study. At 12 months, 50 patients (89.3 %) remained on FFA treatment; 58 % of these patients achieved a ≥50 % sustained response and 10 % experienced seizure freedom. Cognitive, motor, and social improvement were noted in 70.7 %, 36.2 %, and 27.6 % of patients, respectively. The total number of concomitant antiseizure medications was reduced by ≥1 in 29.4 % of patients. No differences were found between DS and LGS patients in these outcomes; age at start of FFA and age at the 12-month timepoint did not have an effect. At least one AE was experienced by 59.7% of patients; in 86.5% of the cases, AEs were plausibly related to treatment. While 70.3% of AEs were self-resolving and 81.8% of the remaining patients experienced mild AEs, 1 patient experienced a serious AE unrelated to FFA which resulted in the patient's death. There were no cases of pulmonary arterial hypertension or ventricular heart disease.

SIGNIFICANCE

The effectiveness and tolerability of FFA treatment in patients with DS or LGS in this retrospective analysis of real-world data were consistent with those seen in randomized clinical trials.

Dravet syndrome: A systematic literature review of the illness burden

We performed a systematic literature review and narrative synthesis according to a pre-registered protocol (Prospero: CRD42022376561) to identify the evidence associated with the burden of illness in Dravet syndrome (DS), a developmental and epileptic encephalopathy characterized by drug-resistant epilepsy with neurocognitive and neurobehavioral impairment. We searched MEDLINE, Embase, and APA PsychInfo, Cochrane's database of systematic reviews, and Epistemonikos from inception to June 2022. Non-interventional studies reporting on epidemiology (incidence, prevalence, and mortality), patient and caregiver health-related quality of life (HRQoL), direct and indirect costs and healthcare resource utilization were eligible. Two reviewers independently carried out the screening. Pre-specified data were extracted and a narrative synthesis was conducted. Overall, 49 studies met the inclusion criteria. The incidence varied from 1:15 400-1:40 900, and the prevalence varied from 1.5 per 100 000 to 6.5 per 100 000. Mortality was reported in 3.7%-20.8% of DS patients, most commonly due to sudden unexpected death in epilepsy and status epilepticus. Patient HRQoL, assessed by caregivers, was lower than in non-DS epilepsy patients; mean scores (0 [worst] to 100/1 [best]) were 62.1 for the Kiddy KINDL/Kid-KINDL, 46.5-54.7 for the PedsQL and 0.42 for the EQ-5D-5L. Caregivers, especially mothers, were severely affected, with impacts on their time, energy, sleep, career, and finances, while siblings were also affected. Symptoms of depression were reported in 47%-70% of caregivers. Mean total direct costs were high across all studies, ranging from $11 048 to $77 914 per patient per year (PPPY), with inpatient admissions being a key cost driver across most studies. Mean costs related to lost productivity were only reported in three publications, ranging from approximately $19 000 to $20 000 PPPY ($17 596 for mothers vs $1564 for fathers). High seizure burden was associated with higher resource utilization, costs and poorer HRQoL. The burden of DS on patients, caregivers, the healthcare system, and society is profound, reflecting the severe nature of the syndrome. Future studies will be able to assess the impact that newly approved therapies have on reducing the burden of DS.

Fenfluramine in the treatment of Dravet syndrome: Results of a third randomized, placebo-controlled clinical trial

OBJECTIVE

This study was undertaken to assess the safety and efficacy of fenfluramine in the treatment of convulsive seizures in patients with Dravet syndrome.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group, phase 3 clinical trial enrolled patients with Dravet syndrome, aged 2-18 years with poorly controlled convulsive seizures, provided they were not also receiving stiripentol. Eligible patients who had ≥6 convulsive seizures during the 6-week baseline period were randomized to placebo, fenfluramine .2 mg/kg/day, or fenfluramine .7 mg/kg/day (1:1:1 ratio) administered orally (maximum dose = 26 mg/day). Doses were titrated over 2 weeks and maintained for an additional 12 weeks. The primary endpoint was a comparison of the monthly convulsive seizure frequency (MCSF) during baseline and during the combined titration-maintenance period in patients given fenfluramine .7 mg/kg/day versus patients given placebo.

RESULTS

A total of 169 patients were screened, and 143 were randomized to treatment. Mean age was 9.3 ± 4.7 years (±SD), 51% were male, and median baseline MCSF in the three groups ranged 12.7-18.0 per 28 days. Patients treated with fenfluramine .7 mg/kg/day demonstrated a 64.8% (95% confidence interval = 51.8%-74.2%) greater reduction in MCSF compared with placebo (p < .0001). Following fenfluramine .7 mg/kg/day, 72.9% of patients had a ≥50% reduction in MCSF compared with 6.3% in the placebo group (p < .0001). The median longest seizure-free interval was 30 days in the fenfluramine .7 mg/kg/day group compared with 10 days in the placebo group (p < .0001). The most common adverse events (>15% in any group) were decreased appetite, somnolence, pyrexia, and decreased blood glucose. All occurred in higher frequency in fenfluramine groups than placebo. No evidence of valvular heart disease or pulmonary artery hypertension was detected.

SIGNIFICANCE

The results of this third phase 3 clinical trial provide further evidence of the magnitude and durability of the antiseizure response of fenfluramine in children with Dravet syndrome.

Pharmacological diversity amongst approved and emerging antiseizure medications for the treatment of developmental and epileptic encephalopathies

Developmental and epileptic encephalopathies (DEEs) are rare neurodevelopmental disorders characterised by early-onset and often intractable seizures and developmental delay/regression, and include Dravet syndrome and Lennox-Gastaut syndrome (LGS). Rufinamide, fenfluramine, stiripentol, cannabidiol and ganaxolone are antiseizure medications (ASMs) with diverse mechanisms of action that have been approved for treating specific DEEs. Rufinamide is thought to suppress neuronal hyperexcitability by preventing the functional recycling of voltage-gated sodium channels from the inactivated to resting state. It is licensed for adjunctive treatment of seizures associated with LGS. Fenfluramine increases extracellular serotonin levels and may reduce seizures via activation of specific serotonin receptors and positive modulation of the sigma-1 receptor. Fenfluramine is licensed for adjunctive treatment of seizures associated with Dravet syndrome and LGS. Stiripentol is a positive allosteric modulator of type-A gamma-aminobutyric acid (GABAA) receptors. As a broad-spectrum inhibitor of cytochrome P450 enzymes, its antiseizure effects may additionally arise through pharmacokinetic interactions with co-administered ASMs. Stiripentol is licensed for treating seizures associated with Dravet syndrome in patients taking clobazam and/or valproate. The mechanism(s) of action of cannabidiol remains largely unclear although multiple targets have been proposed, including transient receptor potential vanilloid 1, G protein-coupled receptor 55 and equilibrative nucleoside transporter 1. Cannabidiol is licensed as adjunctive treatment in conjunction with clobazam for seizures associated with Dravet syndrome and LGS, and as adjunctive treatment of seizures associated with tuberous sclerosis complex. Like stiripentol, ganaxolone is a positive allosteric modulator at GABAA receptors. It has recently been licensed in the USA for the treatment of seizures associated with cyclin-dependent kinase-like 5 deficiency disorder. Greater understanding of the causes of DEEs has driven research into the potential use of other novel and repurposed agents. Putative ASMs currently in clinical development for use in DEEs include soticlestat, carisbamate, verapamil, radiprodil, clemizole and lorcaserin.

Fenfluramine: A Review in Dravet and Lennox-Gastaut Syndromes

Fenfluramine (Fintepla®) is an oral anti-seizure medication (ASM) with a novel mechanism of action consisting of activity in the serotonergic system coupled with positive allosteric modulation effects at sigma-1 receptors. Originally approved for use at high doses as an appetite suppressant, it was subsequently withdrawn after being linked to valvular heart disease (VHD) and pulmonary arterial hypertension (PAH), before being investigated for use at low doses as an adjunctive ASM in patients with developmental epileptic encephalopathies, including Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) who have pharmacoresistant seizures. In clinical trials, treatment with adjunctive fenfluramine markedly reduced convulsive seizure frequency in patients with DS that were sustained for up to 3 years, and reduced drop seizure frequency in patients with LGS that were sustained for up to 1 year. Notably, fenfluramine was also associated with clinically meaningful improvements in aspects of everyday executive functioning (EF) not entirely explainable by seizure reduction alone. Furthermore, it was generally well tolerated with, importantly, no reports of VHD or PAH. Thus, adjunctive fenfluramine is a novel and effective treatment for pharmacoresistant seizures associated with DS and LGS that may also improve aspects of everyday EF in some patients.

Black-Box Warnings of Antiseizure Medications: What is Inside the Box?

Antiseizure medications can cause serious adverse reactions and have deleterious drug interactions that often complicate the clinical management of patients. When the US Food and Drug Administration (FDA) wants to alert healthcare providers and patients about the risk of potentially serious or fatal drug reactions, the FDA requires the manufacturers of these medications to format these warnings within a "black-box" border, and prominently display this box on the first section of the package insert; such warnings are called "black-box warnings (BBWs)". The BBW is a way for the FDA to urge physicians to evaluate patients more rigorously and carefully weigh the risks and benefits, before prescribing medication that has the potential to cause serious adverse reactions, and to formulate a plan for close monitoring during therapy. The FDA BBW provides the extra layer of safety but many healthcare providers fail to comply with these warnings. Currently, there are 26 FDA-approved antiseizure medications in the US market, 38% of which have received BBWs, and most of the antiseizure medications with BBWs are older-generation drugs. Some antiseizure medications have multiple BBWs; for example, valproic acid has three BBWs including hepatotoxicity, fetal risk, and pancreatitis, carbamazepine has BBWs of serious skin and hematological reactions, and felbamate also has two BBWs including hepatic failure and aplastic anemia. The purpose of this review is to provide insight into each BBW received by antiseizure medications and discuss the FDA recommendations for evaluating the drug benefit/risk, and for monitoring parameters before the initiation of and during treatment.

Recent advances in pharmacotherapy for epilepsy

PURPOSE OF REVIEW

Epilepsy affects 70 million people worldwide and is a significant cause of morbidity and early mortality. The mainstay of therapy is oral medications. Epilepsy drug development is escalating, driven by continued drug resistance in up to a third of epilepsy patients. Treatment development now focuses on discovery of novel mechanisms of action and syndrome-specific therapies.

RECENT FINDINGS

Difficult-to-treat epilepsy related to conditions including tuberous sclerosis complex (TSC), Lennox Gastaut syndrome (LGS) and Dravet syndrome (DS) have been the target of recent developments. Disease-modifying therapy for epilepsy related to TSC with vigabatrin at onset of first electroencephalographic epileptiform changes, rather than after first clinical seizure, has demonstrated strongly positive seizure and developmental outcomes. Fenfluramine, approved for DS and, more recently, LGS, has robust data supporting efficacy, safety/tolerability, as well as mortality, quality of life and cognitive function. Rescue therapy has expanded to include better tolerated benzodiazepines in the form of nasal midazolam and valium. Cenobamate, a first-in-class inactivator of the persistent voltage-gated sodium channel and approved for adult partial onset epilepsy, has exceptional efficacy and tolerability and will be expanded to children and to generalized onset epilepsy in adults.

SUMMARY

The repertoire of available and developmental therapies for epilepsy is rapidly expanding, and now includes disease-modifying vigabatrin in TSC and agents with extraordinary efficacy, fenfluramine and cenobamate.

Investigational new drugs for the treatment of Dravet syndrome: an update

INTRODUCTION

While there are already approved anticonvulsants for treatment of children with Dravet syndrome, disease modifying therapy is at its beginning.

AREAS COVERED

This narrative review is updating the latest information about efficacy and safety of both anticonvulsant and disease modifying investigational drugs for Dravet syndrome. Relevant publications were searched for in MEDLINE, GOOGLE SCHOLAR, SCINDEKS, and CLINICALTRIALS.GOV databases, from the dates of their foundation till January 2023.

EXPERT OPINION

The main advancements were made in the treatment of Dravet syndrome with confirmed haploinsufficiency of SCN1A gene. The application of antisense oligonucleotides has so far proven to be the most successful within disease-modifying therapy, but it also requires further refinement of the methodology of application and delivery to target cells, as well as additional testing of the effectiveness of antisense oligonucleotides outside of TANGO technology. Also, the full potential of gene therapy has yet to be explored, given that high capacity adenoviral vectors that can incorporate the SCN1A gene have recently been prepared.

Fenfluramine treatment for Dravet syndrome: Caregiver- and clinician-reported benefits on the quality of life of patients, caregivers, and families living in Germany, Spain, Italy, and the United Kingdom

OBJECTIVE

Clinical trial data and prior preliminary research indicate that fenfluramine (FFA) provides meaningful improvements in seizure-related and quality of life (QOL) outcomes for individuals with Dravet syndrome (DS), their caregivers, and their families. This study sought to replicate and extend these preliminary findings in a new sample of individuals with DS and their families who live in European countries.

METHODS

Study participants were European clinicians and parents caring for individuals with DS who had participated in an EU FFA Early Access Program. Participants completed one-on-one semi-structured interviews and were asked the extent to which they noticed changes in a number of the child's seizure- and non-seizure-related QOL domains after starting FFA treatment. Participants were also asked about the benefits of FFA treatment to the caregivers' lives and for the family unit.

RESULTS

25 parent caregivers and 16 clinicians participated. The caregivers and clinicians reported improvements in both seizure-related (i.e., reductions in seizure activity, improvements in the frequency or type of seizure triggers and post-ictal recovery times, and improved post-seizure function) and non-seizure-related (e.g., cognition, focus, alertness, speech, academic performance, behavior, sleep, motor function) QOL domains after FFA treatment in individuals with DS. Caregivers also reported improved mood and more time for things they enjoyed, felt less overwhelmed, reported better sleep quality, and had less personal and family stress; clinicians corroborated most of these reports. All clinicians (100%) and most (96%) caregivers said they would "very likely" or "quite likely" recommend FFA to others with DS.

CONCLUSIONS

Real-world experience in Europe with FFA treatment is associated with meaningful improvements in many QOL domains for individuals with DS and their families; replicating findings from a previous study of DS patients and their families from the USA. Caregivers and clinicians provided specific examples of the benefits of FFA for people with DS, caregivers, and their families and are very likely to recommend FFA to others with DS.

Psychobehavioural and Cognitive Adverse Events of Anti-Seizure Medications for the Treatment of Developmental and Epileptic Encephalopathies

The developmental and epileptic encephalopathies encompass a group of rare syndromes characterised by severe drug-resistant epilepsy with onset in childhood and significant neurodevelopmental comorbidities. The latter include intellectual disability, developmental delay, behavioural problems including attention-deficit hyperactivity disorder and autism spectrum disorder, psychiatric problems including anxiety and depression, speech impairment and sleep problems. Classical examples of developmental and epileptic encephalopathies include Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex. The mainstay of treatment is with multiple anti-seizure medications (ASMs); however, the ASMs themselves can be associated with psychobehavioural adverse events, and effects (negative or positive) on cognition and sleep. We have performed a targeted literature review of ASMs commonly used in the treatment of developmental and epileptic encephalopathies to discuss the latest evidence on their effects on behaviour, mood, cognition, sedation and sleep. The ASMs include valproate (VPA), clobazam, topiramate (TPM), cannabidiol (CBD), fenfluramine (FFA), levetiracetam (LEV), brivaracetam (BRV), zonisamide (ZNS), perampanel (PER), ethosuximide, stiripentol, lamotrigine (LTG), rufinamide, vigabatrin, lacosamide (LCM) and everolimus. Bromide, felbamate and other sodium channel ASMs are discussed briefly. Overall, the current evidence suggest that LEV, PER and to a lesser extent BRV are associated with psychobehavioural adverse events including aggressiveness and irritability; TPM and to a lesser extent ZNS are associated with language impairment and cognitive dulling/memory problems. Patients with a history of behavioural and psychiatric comorbidities may be more at risk of developing psychobehavioural adverse events. Topiramate and ZNS may be associated with negative effects in some aspects of cognition; CBD, FFA, LEV, BRV and LTG may have some positive effects, while the remaining ASMs do not appear to have a detrimental effect. All the ASMs are associated with sedation to a certain extent, which is pronounced during uptitration. Cannabidiol, PER and pregabalin may be associated with improvements in sleep, LTG is associated with insomnia, while VPA, TPM, LEV, ZNS and LCM do not appear to have detrimental effects. There was variability in the extent of evidence for each ASM: for many first-generation and some second-generation ASMs, there is scant documented evidence; however, their extensive use suggests favourable tolerability and safety (e.g. VPA); second-generation and some third-generation ASMs tend to have the most robust evidence documented over several years of use (TPM, LEV, PER, ZNS, BRV), while evidence is still being generated for newer ASMs such as CBD and FFA. Finally, we discuss how a variety of factors can affect mood, behaviour and cognition, and untangling the associations between the effects of the underlying syndrome and those of the ASMs can be challenging. In particular, there is enormous heterogeneity in cognitive, behavioural and developmental impairments that is complex and can change naturally over time; there is a lack of standardised instruments for evaluating these outcomes in developmental and epileptic encephalopathies, with a reliance on subjective evaluations by proxy (caregivers); and treatment regimes are complex involving multiple ASMs as well as other drugs.