Role of observational studies in supporting extrapolation of efficacy data from adults to children with epilepsy - A systematic review of the literature using lacosamide as an example

Effectiveness and safety of Lacosamide in pediatric patients with epilepsy under four years: Results from a prospective cohort study in China

BACKGROUND

Lacosamide (LCM) has shown promising efficacy and safety outcomes in clinical trials. However, the evidence is limited among pediatric patients especially under four years in real-world. The study investigated the treatment outcomes and safety of LCM in patients under four years based on the data of the epilepsy registry of Children in China.

METHODS

A prospective cohort study was conducted among patients under 4 years who newly received LCM as monotherapy or adjunctive therapy. The treatment outcomes were measured by retention rate of LCM, 50 % response rates and seizure-free rates during follow-up. The retention rate of LCM was assessed using the Kaplan-Meier survival model. Adverse events were reported as a percentage of all participants.

RESULTS

Of 109 participants (mean follow-up: 18.6 months), 59 received LCM as monotherapy and 50 as adjunctive therapy. Sixty patients had focal epilepsy, 44 had generalized epilepsy and 5 had combined generalized and focal epilepsy. 70 % of patients in the monotherapy group and 41 % in the adjunctive therapy group remained on LCM treatment without additional treatments for at least one year. In patients with monotherapy, 50 % response rate and seizure-free rate were 75 % and 56 % at 12 months, respectively. In adjunctive therapy group, these rates were 51 % and 36 %, respectively. Lower baseline seizure frequency in both treatment groups (monotherapy: p < 0.001; adjunctive therapy: p = 0.02) and younger age groups within the monotherapy group (P = 0.04) correlated with a higher LCM retention rate. Adverse events were reported by 15 patients (13.8 %), with somnolence being the most common (7 of 15 patients).

CONCLUSION

With a comprehensive information and high-quality of data, the study demonstrates the effective treatment outcome and safety of LCM. The study adds reliable evidence to exiting real-word evidence of LCM in the specific age group of patients with epilepsy to fill the evidence gap.

Sources of pharmacokinetic and pharmacodynamic variability and clinical pharmacology studies of antiseizure medications in the pediatric population

Multiple treatment options exist for children with epilepsy, including surgery, dietary therapies, neurostimulation, and antiseizure medications (ASMs). ASMs are the first line of therapy, and more than 30 ASMs have U.S. Food and Drug Administration (FDA) approval for the treatment of various epilepsy and seizure types in children. Given the extensive FDA approval of ASMs in children, it is crucial to consider how the physiological and developmental changes throughout childhood may impact drug disposition. Various sources of pharmacokinetic (PK) variability from different extrinsic and intrinsic factors such as patients' size, age, drug-drug interactions, and drug formulation could result in suboptimal dosing of ASMs. Barriers exist to conducting clinical pharmacological studies in neonates, infants, and children due to ethical and practical reasons, limiting available data to fully characterize these drugs' disposition and better elucidate sources of PK variability. Modeling and simulation offer ways to circumvent traditional and intensive clinical pharmacology methods to address gaps in epilepsy and seizure management in children. This review discusses various physiological and developmental changes that influence the PK and pharmacodynamic (PD) variability of ASMs in children, and several key ASMs will be discussed in detail. We will also review novel trial designs in younger pediatric populations, highlight the role of extrapolation of efficacy in epilepsy, and the use of physiologically based PK modeling as a tool to investigate sources of PK/PD variability in children. Finally, we will conclude with current challenges and future directions for optimizing the efficacy and safety of these drugs across the pediatric age spectrum.

Efficacy and safety of lacosamide in pediatric patients with epilepsy: A systematic review and meta-analysis

OBJECTIVE

Lacosamide (LCM), is a third-generation antiseizure medicine, with limited clinical evidence for use in pediatric populations. We aimed to evaluate evidence for the efficacy and safety of LCM in pediatric patients with epilepsy.

METHODS

A systematic review was performed using literature published from inception to February 2022 identified in MEDLINE, Embase, Cochrane Library, and four Chinese databases. Efficacy and safety outcome data were collected, and a meta-analysis was performed.

RESULT

Twenty-one studies involving 1230 pediatric patients were included. The median percent reduction in seizure frequency per 28 days from baseline to maintenance was 33.1% (95% confidence interval [CI] 22.7%, 43.5%). After 6 months of treatment, the 50%, 75%, and 100% responder rates were 53.3% (95% CI 40.7%, 65.9%), 28.3% (95% CI 20.8%, 35.8%), and 20.4% (95% CI 12.6%, 28.2%), respectively. After 12 months of treatment, the 50%, 75%, and 100% responder rates were 42.0% (95% CI 29.5%, 54.5%), 19.5% (95% CI 11.1%, 27.8%), and 15.2% (95% CI 6.6%, 23.8%), respectively. The most common adverse events (AEs) were drowsiness (15.0%), dizziness (9.9%), and somnolence (8.3%).

CONCLUSION

Lacosamide is generally effective and well tolerated to use in children with epilepsy. However, further research with high-quality data and long-term follow-up of LCM use in pediatric populations is needed.

Treatment of Focal-Onset Seizures in Children: Should This Be More Etiology-Driven?

To accelerate the process of licensing antiseizure medication (ASM) in children, extrapolation of efficacy data for focal-onset seizures from adults to children ≥2 or ≥4 years of age is now accepted. We summarized the efficacy evidence from randomized, controlled trials that was used to grant approval for the pediatric indication of focal-onset seizures for the different ASMs available in Europe. Data from high-quality randomized, controlled trials in young children are limited, especially on the use of ASMs in monotherapy. Licensure trials are typically focused on seizure type irrespective of etiology or epilepsy syndrome. We elaborate on the importance of etiology- or syndrome-driven research and treatment, illustrating this with examples of childhood epilepsy syndromes characterized by predominantly focal-onset seizures. Some of these syndromes respond well to standard ASMs used for focal-onset seizures, but others would benefit from a more etiology- or syndrome-driven approach. Advances in molecular genetics and neuroimaging have made it possible to reveal the underlying cause of a child's epilepsy and tailor research and treatment. More high-quality randomized, controlled trials based on etiology or syndrome type are needed, including those assessing effects on cognition and behavior. In addition, study designs such as "N-of-1 trials" could elucidate possible new treatment options in rare epilepsies. Broadening incentives currently in place to stimulate the development and marketing of drugs for rare diseases (applicable to some epilepsy syndromes) to more common pediatric epilepsy types and syndromes might be a means to enable high-quality trials, and ultimately allow more evidence-based treatment in children.

Why we urgently need improved seizure and epilepsy therapies for children and neonates

In contrast to epilepsy in adolescents and adults, neonatal seizures and early onset epilepsy poses unique challenges with significant repercussion for treatment choices. Most importantly, high seizure burden and epileptic encephalopathy are associated with developmental, behavioural and cognitive problems. The causes are multifactorial and include etiology, seizure burden, epileptic encephalopathy, but also antiseizure medication. In contrast to adults and older children only very few drugs have been licenced for infants and neonates, and after a long delay. Very recently, extrapolation of adult data has become possible as a path to speed up drug development for younger children but this is not necessarily possible for infants and neonates. With the advances in understanding the molecular basis of many epilepsies, targeted therapies become available, for example for KCNQ2 mutation related epilepsies, Dravet syndrome or tuberous sclerosis complex. Drug trials in neonates are particularly challenging because of their inconspicuous clinical presentation, the need for continuous EEG monitoring, high co-morbidity, and poor response to antiepileptic drugs. There is an urgent need for development of new drugs, evaluation of safety and efficacy of current antiseizure drugs, as well as for national policies and guidelines for the management of seizures and epilepsy in neonates and infants. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.