Faculty Bibliography

Rationale: The Generalized Tonic-Clonic Convulsion (GTCC) is often associated with post-ictal electrographic slowing, and at times suppression. The mechanism of post-ictal EEG suppression is not known but may reflect involvement of bilateral subcortical networks. We examined the electrographic activity occurring after seizures with bilateral movement to determine if there are post-ictal features unique to the GTCC. Methods: We reviewed the video EEG of 100 consecutive inpatients of the NYU Comprehensive Epilepsy Center that had bilateral movement as part of their seizure semiology. Each seizure was reviewed by 2 reviewers; any records in which the patient was obscured on the video were excluded from further analysis. Any seizure with bilateral symmetric tonic, vibratory and clonic phases (defined as bilateral movement > and < 5 Hz respectively) in that order was categorized as "typical GTCC" (tGTCC). If one phase was absent, asymmetric or the progression was different, it was considered an "atypical GTCC" (aGTCC). If two phases were absent it was not a GTCC (nGTCC). All aGTCC were reviewed by at least 3 reviewers. The post-ictal EEG was categorized as: "suppression", defined as background voltage <10uV; "slowing" defined as decreased amplitude and/or frequency compared to baseline while still >10uV; or "no change from baseline." Results: 104 seizures from 100 patients were reviewed, 5 patients were excluded due to obscured video or EEG, leaving 97 seizures reviewed. 41 were tGTCC, 14 were aGTCC and 42 were nGT

Despite the expanding treatment options in the past two decades, a third of patients with epilepsy remain treatment resistant, and there is a continued need for new therapies. After many years of repeated success, several late-stage clinical development programs for antiseizure drugs have seen unexpected failures to demonstrate superiority of the experimental drug over placebo, which has led to a re-examination of how clinical trials are conducted in this heterogeneous and often unpredictable condition. There are numerous sources of variability in epilepsy trials that can reduce effect size. Methods to improve diagnostic accuracy and outcome assessment are needed to ensure that promising compounds have the best chance to get to patients. 2013 Future Science Ltd

A working group was created to address clinical "gaps to care" as well as opportunities for development of new treatment approaches for epilepsy. The working group primarily comprised clinicians, trialists, and pharmacologists. The group identified a need for better animal models for both efficacy and tolerability, and noted that animal models for potential disease-modifying or antiepileptogenic effect should mirror conditions in human trials. For antiseizure drugs (ASDs), current animal models have not been validated with respect to their relationship to efficacy in common epilepsy syndromes. The group performed an "expert opinion" survey of perceived efficacy of the available ASDs, and identified a specific unmet need for ASDs to treat tonic-atonic and myoclonic seizures. No correlation has as yet been demonstrated between animal models of tolerability and adverse effects (AEs), versus tolerability in humans. There is a clear opportunity for improved therapies in relation to dose-related AEs. The group identified common and rare epilepsy syndromes that could represent opportunities for clinical trials. They identified opportunities for antiepileptogenic (AEG) therapies in both adults and children, acknowledging that the presence of a biomarker would substantially improve the chances of a successful trial. However, the group acknowledged that disease-modifying therapies (given after the first seizure or after the development of epilepsy) would be easier to study than AEG therapies.

Purpose of Review: Selection of the ideal antiepileptic drug (AED) for an individual patient can be a daunting process. Choice of treatment should be based on several factors, including but not limited to epilepsy classification, AED mechanism of action, AED side-effect profile, and drug interactions. Special consideration must be given to populations such as women, older adults, patients with other medical comorbidities, and patients who are newly diagnosed.Recent Findings: Head-to-head trials between AEDs in newly diagnosed patients rarely demonstrate that one AED is more or less effective. The second-generation drugs, lamotrigine, topiramate, oxcarbazepine, zonisamide, and levetiracetam, have undergone head-to-head trials confirming similar efficacy and equal or better tolerability than standard drugs in focal epilepsy.Summary: A thoughtful approach to the AED selection process must factor in data from clinical AED trials as well as a variety of patient characteristics and confounding factors. When neurologists apply an individualized approach to AED drug selection for their patients, they can find an effective and well-tolerated drug for most patients.

PURPOSE OF REVIEW: Preclinical research in epileptology has been very successful in producing effective drugs. Unfortunately, however, seizures are still not adequately controlled in a third of the affected individuals, and comorbidities still impose a major burden on the quality of life. New preclinical and clinical drug development strategies are needed to identify drugs that target these unmet medical needs. RECENT FINDINGS: Even in recent years, the antiseizure approach based on screenings has contributed to the identification of new drugs. Thus, it should not be abandoned. However, we propose that a radically new approach, specifically designed to tackle the existing gaps in care, should be developed to complement the traditional screening. This new approach will require integrated strategies for preclinical screening and experimental trial design. In this review, we will attempt to address some of the issues that must be resolved to engage this effort. Are there suitable models to tackle the unmet therapeutic needs in epilepsy? Are there ways to de-risk the transition from preclinical to clinical studies? Are there ways to improve the efficiency of clinical trials and to design ad hoc trials for the unmet therapeutic needs? SUMMARY: Development and validation of a new, integrated strategy for antiepilepsy drug development is needed to identify truly innovative drugs.

OBJECTIVE: Preapproval randomized controlled trials of antiepileptic drugs provide data in limited patient groups. We assessed the side effect and seizure reduction profile of tiagabine (TGB) in typical clinical practice. METHODS: Investigators recorded adverse effect (AE), seizure, and assessment-of-benefit data prospectively in sequential patients treated open label with TGB. RESULTS: Two hundred ninety-two patients (39 children) were enrolled to be treated long term with TGB. Seizure types were focal-onset (86%), generalized-onset (12%), both focal- and generalized-onset (0.3%), and multiple associated with Lennox-Gastaut Syndrome (2%). Two hundred thirty-one received at least one dose of TGB (median=28mg/day) and had follow-up seizure or AE data reported. Common AEs were fatigue, dizziness, psychomotor slowing, ataxia, gastrointestinal upset, weight change, insomnia, and "others" (mostly behavioral). Serious AEs occurred in 19 patients: behavioral effects (n=12), status epilepticus (n=3), others (n=3), and sudden unexplained death (n=1). No patients experienced suicidal ideation/behavior, rash, nephrolithiasis, or organ failure. Seizure outcomes were seizure freedom (5%), >/=75% reduction (12%), >/=50% reduction (23%), and increased number of seizures (17%), or new seizure type (1%). CONCLUSIONS: Behavioral AEs occurred in a larger proportion of patients compared to those reported in TGB preapproval randomized controlled trials. A moderate percentage of patients had a meaningful reduction in seizure frequency. In clinical practice, TGB remains a useful antiepileptic drug.

The ideal proof-of-principle study design provides a strong efficacy signal over the shortest duration, while exposing the fewest patients possible. Data from a large database (Pfizer Inc) which studied add-on pregabalin for the treatment of partial seizures was used to model how duration of baseline, post-randomization treatment period, and number of subjects impact the likelihood of an interpretable efficacy signal. Data from four double-blind, randomized, placebo-controlled, phase III studies that had at least one 600mg/day treatment arm were combined. The common 6-week baseline period was divided into weekly intervals, as was the 12-week post-randomization period. Two methods of analysis were used: logistic regression performed on 50% responder rate and the Hodges-Lehmann estimate on percentage reduction from baseline seizure rate. A simulation-based re-sampling approach was used to determine sufficient sample size. Four weeks of baseline with 3 weeks of treatment were determined to be clinically and statistically sufficient. A reasonable sample size was estimated to be 40-50 patients per group, if a highly efficacious drug was used. These modeling results indicate that the efficacy of an antiepileptic drug can be demonstrated in a relatively short period of time with a reasonable sample size.