Perampanel for Treatment of People with a Range of Epilepsy Aetiologies in Clinical Practice: Evidence from the PERMIT Extension Study

Abstract Introduction It is important to assess the effectiveness of an antiseizure medication in treating different epilepsy aetiologies to optimise individualised therapeutic approaches. Data from the PERaMpanel pooled analysIs of effecTiveness and tolerability (PERMIT) Extension study were used to assess the effectiveness and safety/tolerability of perampanel (PER) when used to treat individuals with a range of epilepsy aetiologies in clinical practice. Methods A post hoc analysis was conducted of PERMIT Extension data from individuals with a known aetiology. Retention was assessed after 3, 6 and 12 months. Effectiveness was assessed after 3, 6 and 12 months and at the last visit (last observation carried forward). Effectiveness assessments included responder rate (≥ 50% seizure frequency reduction) and seizure freedom rate (no seizures since at least the prior visit). Safety/tolerability was assessed by evaluating adverse events (AEs) and AEs leading to discontinuation. Results PERMIT Extension included 1945 individuals with structural aetiology, 1012 with genetic aetiology, 93 with an infectious aetiology, and 26 with an immune aetiology. Retention rates at 12 months were 61.1% (structural), 65.9% (genetic), 56.8% (infectious) and 56.5% (immune). At the last visit, responder rates (total seizures) were 43.3% (structural), 68.3% (genetic), 37.0% (infectious) and 20.0% (immune), and corresponding seizure freedom rates were 15.8%, 46.5%, 11.1% and 5.0%, respectively. AE incidence rates were 58.0% (structural), 46.5% (genetic), 51.1% (infectious) and 65.0% (immune), and corresponding rates of discontinuation due to AEs over 12 months were 18.9%, 16.4%, 18.5% and 21.7%, respectively. The types of AEs reported were generally consistent across aetiology subgroups, with no idiosyncratic AEs emerging. Conclusion Although PER was effective and generally well tolerated when used to treat individuals with a range of epilepsy aetiologies in clinical practice, variability in its effectiveness and tolerability across the subgroups indicates that PER may be particularly useful for individuals with specific epilepsy aetiologies.