A revisited strategy for antiepileptic drug development in children: designing an initial exploratory step

Medical treatment in infants and young children with epilepsy: Off-label use of antiseizure medications. Survey Report of ILAE Task Force Medical Therapies in Children

OBJECTIVE

Antiseizure medications (ASMs) remain the mainstay of epilepsy treatment. These ASMs have mainly been tested in trials in adults with epilepsy, which subsequently led to market authorization (MA). For treatment of - especially young - children with epilepsy, several ASMs do not have a MA and guidelines are lacking, subsequently leading to "off-label" use of ASMs. Even though "off-label" ASM prescriptions for children could lead to more adverse events, it can be clinically appropriate and rational if the benefits outweigh the risks. This could be the case if "on-label" ASM, in mono- or polytherapy, fails to achieve adequate seizure control.

METHODS

The Medical Therapies Task Force of the International League Against Epilepsy (ILAE) Commission for Pediatrics performed a survey to study the current treatment practices in six classic, early life epilepsy scenarios. Our aim was not only to study first- and second-line treatment preferences but also to illustrate the use of "off-label" drugs in childhood epilepsies.

RESULTS

Our results reveal that several ASMs (e.g. topiramate, oxcarbazepine, benzodiazepines) are prescribed "off-label" in distinct scenarios of young children with epilepsy. In addition, recent scientific guidelines were not always adopted by several survey respondents, suggesting a potential knowledge gap.

SIGNIFICANCE

We report the relatively common use of "off-label" prescriptions that underlines the need for targeted and appropriately designed clinical trials, including younger patients, which will also result in the ability to generate evidence-based guidelines.

Drug Development for Rare Paediatric Epilepsies: Current State and Future Directions

Rare diseases provide a challenge in the evaluation of new therapies. However, orphan drug development is of increasing interest because of the legislation enabling facilitated support by regulatory agencies through scientific advice, and the protection of the molecules with orphan designation. In the landscape of the rare epilepsies, very few syndromes, namely Dravet syndrome, Lennox-Gastaut syndrome and West syndrome, have been subject to orphan drug development. Despite orphan designations for rare epilepsies having dramatically increased in the past 10 years, the number of approved drugs remains limited and restricted to a handful of epilepsy syndromes. In this paper, we describe the current state of orphan drug development for rare epilepsies. We identified a large number of compounds currently under investigation, but mostly in the same rare epilepsy syndromes as in the past. A rationale for further development in rare epilepsies could be based on the match between the drug mechanisms of action and the knowledge of the causative gene mutation or by evidence from animal models. In case of the absence of strong pathophysiological hypotheses, exploratory/basket clinical studies could be helpful to identify a subpopulation that may benefit from the new drug. We provide some suggestions for future improvements in orphan drug development such as promoting paediatric drug investigations, better evaluation of the incidence and the prevalence, together with the natural history data, and the development of new primary outcomes.

Safety and tolerability profile of new antiepileptic drug treatment in children with epilepsy

INTRODUCTION

Treatment of pediatric epilepsy requires a careful evaluation of the safety and tolerability profile of antiepileptic drugs (AEDs) to avoid or minimize as much as possible adverse events (AEs) on various organs, hematological parameters, and growth, pubertal, motor, cognitive and behavioral development.

AREAS COVERED

Treatment-emergent AEs (TEAEs) reported in the literature 2000-2018 regarding second- and third-generation AEDs used in the pediatric age, with exclusion of the neonatal period that exhibits specific peculiarities, have been described on the basis of their frequency, severity/tolerability, and particular association with a given AED.

EXPERT OPINION

Somnolence/sedation and behavioral changes, like irritability and nervousness, are among the most commonly observed TEAEs associated with almost all AEDs. Lamotrigine, Gabapentin, Oxcarbazepine, and Levetiracetam appear to be the best-tolerated AEDs with a ≤2% withdrawal rate, while Tiagabine and Everolimus are discontinued in up to >20% of the patients because of intolerable TEAEs. For some AEDs, literature data are scanty to draw a high-level evidence on their safety and tolerability profile. The reasons are: insufficient population size, short duration of treatments, or lack of controlled trials. A future goal is that of identifying clearer, easier, and more homogeneous methodological strategies to facilitate AED testing in pediatric populations.

Off-label use and manipulations of antiepileptic drugs in children: Analysis of the outpatient prescriptions in a tertiary center

OBJECTIVES

Little is known about off-label use and manipulations to achieve the prescribed dose of antiepileptic drugs (AEDs) in outpatient prescriptions. This study aimed to evaluate this practice in a tertiary center for child epilepsy.

METHODS

We reviewed off-label use and manipulations of AEDs delivered to the outpatient's epilepsy clinic. Multivariate logistic regressions were used to determine the factors associated with off-label and manipulated uses.

RESULTS

Five hundred eleven consultations generated 897 AED deliveries (1.75/consultation). Off-label use involved 182 (20.3%) of prescribed AEDs. Factors associated with off-label use were polytherapy and new AEDs while increase of age and nondevelopmental and structural-metabolic etiologies have a protective effect. Among the 1725 doses of AEDs prescribed per day, 33.5% generated manipulations (n=582): 40% inadequate (n=237) and 60% adequate (203 syrups, 112 scored tablets, 30 drops medicine). Polytherapy (p<10^-4) and the absence of market authorization significantly favored manipulations whereas the increase in age restricted them.

CONCLUSION

Off-label use and manipulations of AEDs remain an important problem in home care of children with epilepsy. This is mainly a concern for the most vulnerable groups, i.e., young patients, patients undergoing polytherapy, and patients with developmental and epileptic encephalopathy (DEE). International initiatives have been launched to improve the availability of labeled and adapted drugs in this population.

Antiepileptic drugs for the treatment of infants with severe myoclonic epilepsy

BACKGROUND

This is an updated version of the original Cochrane review published in 2015, Issue 10.Severe myoclonic epilepsy in infants (SMEI), also known as Dravet syndrome, is a rare, refractory form of epilepsy, for which stiripentol (STP) has been recently licensed as add-on therapy.

OBJECTIVES

To evaluate the efficacy and tolerability of STP and other antiepileptic drug treatments (including ketogenic diet) for patients with SMEI.

SEARCH METHODS

For the latest update we searched the Cochrane Epilepsy Group Specialized Register (20 December 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 20 December 2016), MEDLINE (Ovid, 1946 to 20 December 2016) and ClinicalTrials.gov (20 December 2016). Previously we searched the World Health Organization (WHO) International Clinical Trials Registry Platform ICTRP, but this was not usable at the time of this update. We also searched the bibliographies of identified studies for additional references. We handsearched selected journals and conference proceedings and imposed no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-randomised controlled trials; double- or single-blinded or unblinded trials; and parallel-group studies. Administration of at least one antiepileptic drug therapy given singly (monotherapy) or in combination (add-on therapy) compared with add-on placebo or no add-on treatment.

DATA COLLECTION AND ANALYSIS

Review authors independently selected trials for inclusion according to predefined criteria, extracted relevant data and evaluated the methodological quality of trials. We assessed the following outcomes: 50% or greater seizure reduction, seizure freedom, adverse effects, proportion of dropouts and quality of life. We assessed outcomes by using a Mantel-Haenszel meta-analysis to calculate risk ratios (RRs) with 95% confidence intervals (95% CIs).

MAIN RESULTS

Since the last version of this review no new studies have been found. Specifically, we found no RCTs assessing drugs other than STP. The review includes two RCTs evaluating use of STP (total of 64 children). Both studies were generally at unclear risk of bias. A significantly higher proportion of participants had 50% or greater reduction in seizure frequency in the STP group compared with the placebo group (22/33 versus 2/31; RR 10.40, 95% CI 2.64 to 40.87). A significantly higher proportion of participants achieved seizure freedom in the STP group compared with the placebo group (12/33 versus 1/31; RR 7.93, 95% CI 1.52 to 41.21). Investigators found no significant differences in proportions of dropouts from the STP group compared with the placebo group (2/33 versus 8/31; RR 0.24, 95% CI 0.06 to 1.03). Only one study explicitly reported the occurrence of side effects, noting that higher proportions of participants in the STP group experienced side effects than in the placebo group (100% versus 25%; RR 3.73, 95% CI 1.81 to 7.67). We rated the quality of the evidence as low to moderate according to GRADE criteria, as most information is from studies judged to be at an unclear risk of bias.

AUTHORS' CONCLUSIONS

Data derived from two small RCTs indicate that STP is significantly better than placebo with regards to 50% or greater reduction in seizure frequency and seizure freedom. Adverse effects occurred more frequently with STP. Additional adequately powered studies with long-term follow-up should be conducted to unequivocally establish the long-term efficacy and tolerability of STP in the treatment of patients with SMEI.

Stiripentol and vigabatrin current roles in the treatment of epilepsy

INTRODUCTION

Stiripentol and vigabatrin are the two anticonvulsant drugs currently approved in severe infantile-onset epilepsies, respectively Dravet syndrome and infantile spasms.

AREAS COVERED

For both, the indication was discovered by chance thanks to an exploratory study. Both demonstrated indisputable efficacy through randomized-controlled trials. Stiripentol as adjunctive therapy to clobazam and valproate performed better than placebo, and vigabatrin as first-line monotherapy better than the reference steroid therapy in spasms due to tuberous sclerosis. At one-year treatment vigabatrin and steroids were equally efficient in the other etiologies of spasms. However, it took more than 20 years for both drugs to be approved world-wide.

EXPERT OPINION

Stiripentol suffered from pharmacokinetic potentiation of clobazam, thus raising the question whether it was efficient per se. Finally, animal models and pharmacogenetic data on CYP2C19 confirmed its specific anticonvulsant effect. Stiripentol (in comedication with clobazam and valproate) is therefore to be recommended for Dravet patients. Vigabatrin was found to have a frequent and irreversible retinal toxicity, which required an alternative visual testing to be detected in young children. Today the benefit/risk ratio of vigabatrin as first-line is considered to be positive in infantile spasms, given the severity of this epilepsy and the lack of a safer alternative therapy.

Antiepileptic drugs for the treatment of infants with severe myoclonic epilepsy

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 11, 2013.Severe myoclonic epilepsy in infants (SMEI), also known as Dravet syndrome, is a rare, refractory form of epilepsy, for which stiripentol (STP) has been recently licensed as add-on therapy.

OBJECTIVES

To evaluate the efficacy and tolerability of STP and other antiepileptic drug treatments (including ketogenic diet) for patients with SMEI.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (27 April 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 27 April 2015) and MEDLINE (1946 to 27 April 2015). We systematically searched the online trials registry ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform and the bibliographies of identified studies for additional references. We handsearched selected journals and conference proceedings and imposed no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-randomised controlled trials; double- or single-blinded or unblinded trials; and parallel-group studies. Administration of at least one antiepileptic drug therapy given singly (monotherapy) or in combination (add-on therapy) compared with add-on placebo or no add-on treatment.

DATA COLLECTION AND ANALYSIS

Review authors independently selected trials for inclusion according to predefined criteria, extracted relevant data and evaluated the methodological quality of trials. We assessed the following outcomes: 50% or greater seizure reduction, seizure freedom, adverse effects, proportion of dropouts and quality of life. We assessed outcomes by using a Mantel-Haenszel meta-analysis to calculate risk ratios (RRs) with 95% confidence intervals (95% CIs).

MAIN RESULTS

In the updated search, we identified no additional studies suitable for inclusion. We found no RCTs assessing drugs other than STP. The previous version of this review included two RCTs evaluating use of STP (total of 64 children). Both studies were generally at unclear risk of bias. A significantly higher proportion of participants had 50% or greater reduction in seizure frequency in the STP group compared with the placebo group (22/33 vs 2/31; RR 10.40, 95% CI 2.64 to 40.87). A significantly higher proportion of participants achieved seizure freedom in the STP group compared with the placebo group (12/33 vs 1/31; RR 7.93, 95% CI 1.52 to 41.21). Investigators found no significant differences in proportions of dropouts from the STP group compared with the placebo group (2/33 vs 8/31; RR 0.24, 95% CI 0.06 to 1.03). Only one study explicitly reported the occurrence of side effects, noting that higher proportions of participants in the STP group experienced side effects than in the placebo group (100% vs 25%; RR 3.73, 95% CI 1.81 to 7.67).

AUTHORS' CONCLUSIONS

Data derived from two small RCTs indicate that STP is significantly better than placebo with regards to 50% or greater reduction in seizure frequency and seizure freedom. Adverse effects occurred more frequently with STP. Additional adequately powered studies with long-term follow-up should be conducted to unequivocally establish the long-term efficacy and tolerability of STP in the treatment of patients with SMEI.

Pharmacological characterization of an antisense knockdown zebrafish model of Dravet syndrome: inhibition of epileptic seizures by the serotonin agonist fenfluramine

Dravet syndrome (DS) is one of the most pharmacoresistant and devastating forms of childhood epilepsy syndromes. Distinct de novo mutations in the SCN1A gene are responsible for over 80% of DS cases. While DS is largely resistant to treatment with existing anti-epileptic drugs, promising results have been obtained in clinical trials with human patients treated with the serotonin agonist fenfluramine as an add-on therapeutic. We developed a zebrafish model of DS using morpholino antisense oligomers (MOs) targeting scn1Lab, the zebrafish ortholog of SCN1A. Zebrafish larvae with an antisense knockdown of scn1Lab (scn1Lab morphants) were characterized by automated behavioral tracking and high-resolution video imaging, in addition to measuring brain activity through local field potential recordings. Our findings reveal that scn1Lab morphants display hyperactivity, convulsive seizure-like behavior, loss of posture, repetitive jerking and a myoclonic seizure-like pattern. The occurrence of spontaneous seizures was confirmed by local field potential recordings of the forebrain, measuring epileptiform discharges. Furthermore, we show that these larvae are remarkably sensitive to hyperthermia, similar to what has been described for mouse models of DS, as well as for human DS patients. Pharmacological evaluation revealed that sodium valproate and fenfluramine significantly reduce epileptiform discharges in scn1Lab morphants. Our findings for this zebrafish model of DS are in accordance with clinical data for human DS patients. To our knowledge, this is the first study demonstrating effective seizure inhibition of fenfluramine in an animal model of Dravet syndrome. Moreover, these results provide a basis for identifying novel analogs with improved activity and significantly milder or no side effects.

The case for assessing cannabidiol in epilepsy

Intractable epilepsies have an extraordinary impact on cognitive and behavioral function and quality of life, and the treatment of seizures represents a challenge and a unique opportunity. Over the past few years, considerable attention has focused on cannabidiol (CBD), the major nonpsychotropic compound of Cannabis sativa. Basic research studies have provided strong evidence for safety and anticonvulsant properties of CBD. However, the lack of pure, pharmacologically active compounds and legal restrictions have prevented clinical research and confined data on efficacy and safety to anecdotal reports. Pure CBD appears to be an ideal candidate among phytocannabinoids as a therapy for treatment-resistant epilepsy. A first step in this direction is to systematically investigate the safety, pharmacokinetics, and interactions of CBD with other antiepileptic drugs and obtain an initial signal regarding efficacy at different dosages. These data can then be used to plan double-blinded placebo-controlled efficacy trials. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.

Antiepileptic drugs for the treatment of severe myoclonic epilepsy in infancy

BACKGROUND

Severe myoclonic epilepsy in infants (SMEI), also known as Dravet syndrome, is a rare, refractory form of epilepsy, for whose treatment stiripentol (STP) has been recently licensed for add-on use.

OBJECTIVES

To evaluate the efficacy and tolerability of STP and other antiepileptic drug treatments (including ketogenic diet) as therapy for patients with SMEI.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (15 May 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 4 of 12, The Cochrane Library, April 2013), MEDLINE (1946 to May 2013) and SCOPUS (1823 to May 2013). The online trials registries ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were systematically searched. The bibliographies of any identified study were searched for further references. We handsearched selected journals and conference proceedings. No language restrictions were imposed.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-randomised controlled trials; double- or single-blinded or unblinded trials; and parallel-group studies. Administration of at least one antiepileptic drug therapy given singly (monotherapy) or in combination (add-on therapy) compared with add-on placebo or no add-on treatment.

DATA COLLECTION AND ANALYSIS

Review authors independently selected trials for inclusion according to predefined criteria, extracted relevant data and evaluated the methodological quality of trials. The following outcomes were assessed: at least 50% seizure reduction, seizure freedom, adverse effects, proportion of dropouts and quality of life. Outcomes were assessed using a Mantel-Haenszel meta-analysis to calculate risk ratio (RR) with 95% confidence intervals (95% CIs).

MAIN RESULTS

No RCTs assessing drugs other than STP were found. Two RCTs evaluating the use of STP (total of 64 children) were included. Both studies were generally at unclear risk of bias. A significantly higher proportion of participants had 50% or greater reduction in seizure frequency in the STP group compared with the placebo group (22/33 vs 2/31; RR 10.40, 95% CI 2.64 to 40.87). A significantly higher proportion of participants achieved seizure freedom in the STP group compared with the placebo group (12/33 vs 1/31; RR 7.93, 95% CI 1.52 to 41.21). No significant difference in the proportion of dropouts was found in the STP group compared with the placebo group (2/33 vs 8/31; RR 0.24, 95% CI 0.06 to 1.03). Only one study explicitly reported the occurrence of side effects; higher proportions of participants were reported to experience side effects in the STP group compared with the placebo group (100% vs 25%; RR 3.73, 95% CI 1.81 to 7.67).

AUTHORS' CONCLUSIONS

Data derived from two small RCTs indicate that STP is significantly better than placebo with regards to 50% or greater reduction in seizure frequency and seizure freedom. Adverse effects occurred more frequently with STP. Further adequately powered studies with long-term follow-up should be conducted to unequivocally establish the long-term efficacy and tolerability of STP in the treatment of SMEI.