Effect of adjunctive perampanel on myoclonic and absence seizures: post-hoc analysis of data from the Extension Phase of a Phase III study in patients with idiopathic generalized epilepsy (IGE) (P3.236)

Objective: To assess the effects of adjunctive perampanel on myoclonic and absence seizures in IGE.

Background: Perampanel is a selective, non-competitive AMPA receptor antagonist, approved for adjunctive treatment of focal seizures, with or without secondarily generalized seizures, and for primary generalized tonic-clonic (PGTC) seizures in patients with epilepsy aged ≥12 years. Approval for PGTC seizures was based on the placebo-controlled Phase III Study 332 in patients with PGTC seizures and IGE. Since some AEDs can aggravate seizures in IGE, a post-hoc analysis was performed to assess myoclonic and absence seizure outcomes in the Extension Phase of Study 332.

Design/Methods: Study 332 methodology has been published (French et al. Neurology 2015;85:950–957). Patients completing the Double-blind study could receive perampanel during an Extension Phase, including a 6-week blinded Conversion Period (dose optimized to maximum of 12 mg/day) and up to 136 weeks’ unblinded Maintenance. For this post-hoc analysis, the following endpoints were assessed for absence and myoclonic seizures across the Extension Phase: median percent changes in seizure frequency per 28 days, and proportions of patients achieving reductions in seizure frequency of ≥50% (50% responder rate) or 100% (seizure freedom rate).

Results: Of 138 patients entering the Extension Phase, 76 experienced myoclonic (n=46) and/or absence (n=52) seizures at Pre-perampanel Baseline. At Weeks 40–52 of perampanel treatment, data were available for 65 of these patients (myoclonic, n=40; absence, n=43). At this time window, median percent changes in seizure frequency were −100.0% for both seizure types, 50% responder rates were 82.5% for myoclonic and 76.7% for absence seizures, and seizure freedom rates were 57.5% for myoclonic and 55.8% for absence seizures.

Conclusions: In this small, post-hoc analysis, median percent changes in frequency did not indicate any overall worsening of myoclonic or absence seizures in patients with IGE.

Study Supported by: Eisai Inc.

Disclosure: Dr. Brandt has received personal compensation for activities with Eisai, UCB and Desitin as a consultant, speaker and advisory board member. Dr. Wechsler has received personal compensation for activities with Cyberonics, Eisai, Sunovion, Marinus, and Lundbeck. Dr. O'Brien has received personal compensation for activities with UCB Pharma and Eisai Inc. Dr. O'Brien has received research support from Eisai Inc., UCB Pharma, Sanofi-Aventis Pharmaceuticals, Inc., SciGen, Marinus and UPS. Dr. Laurenza has received personal compensation for activities with Eisai Inc. as an employee. Dr. Patten has received personal compensation for activities with Eisa Ltd as an employee. Dr. Bibbiani has received personal compensation for activities with Eisai Inc. as an employee. Dr. Williams has received personal compensation for activities with Eisai, Inc.