Open-label study to investigate the safety and efficacy of adjunctive perampanel in pediatric patients (aged 4 to <12 years) with inadequately controlled focal-onset seizures: Japanese subgroup analysis.

• We assessed perampanel outcomes for pediatric Japanese patients from study 311. • Adjunctive perampanel for FOS was generally safe and well tolerated. • Perampanel was efficacious regardless of seizure types or EIASM status. • Perampanel is an effective treatment option in Japanese pediatric patients with FOS. To evaluate the safety and tolerability of adjunctive perampanel in a Japanese subpopulation of Study 311 (NCT02849626), which was a global, multicenter, open-label, single-arm study of children (aged 4 to <12 years) with inadequately controlled focal-onset seizures (FOS), with or without focal to bilateral tonic-clonic seizures (FBTCS) or generalized tonic-clonic seizures (GTCS). Study 311 comprised a Core Study, Extension A, and Extension B; this report focuses on the Japanese patient subgroup in the Core Study only. In the Core Study, Japanese patients (FOS only) received adjunctive perampanel ≤12 mg/day in a 23-week Treatment Phase. Endpoints included safety/tolerability (primary) and median percent change in seizure frequency per 28 days from baseline. Patients were stratified by age and concomitant enzyme-inducing anti-seizure medication (EIASM) use. Of 65 enrolled Japanese patients, 56 completed the Core Study and nine withdrew. The most common reason for discontinuation was adverse events (AEs) (n = 4 [6.2%]). The mean (standard deviation) daily dose of perampanel in Japanese FOS patients was 5.8 (2.2) mg/day. During the Core Study, treatment-emergent AEs (TEAEs) were reported by 89% of Japanese patients, most commonly nasopharyngitis (28%) and somnolence (28%). The median percent reduction in seizure frequency per 28 days from baseline was 37% and the lower limit of the 95% CI was greater than 10.5%, satisfying the pre-defined efficacy criteria. Perampanel was effective regardless of age or concomitant EIASM use. Perampanel as adjunctive therapy is generally safe, well-tolerated, and efficacious in Japanese children aged 4 to <12 years with FOS (with/without FBTCS). [ABSTRACT FROM AUTHOR]