SAS included 1703 patients (trial: n=427; non-trial: n=1276). Most patients received 1–2 (trial: 29.7%, n=127/427; non-trial: 26.2%, n=334/1276) prior anti-seizure medications. Discontinuation rates were 47.8% (trial, n=204/427) and 47.6% (non-trial, n=608/1276). Most common primary reason for discontinuation was adverse events (26.7%, trial; 21.6%, non-trial). Mean (standard deviation) maximum doses were 7.0 (3.1) (trial) and 6.5 (3.2) (non-trial) mg/day. Based on known titration schedules, the most common schedule at trial sites was every 2 weeks (39.1%) and at non-trial sites was weekly (23.4%). Retention rates at 24 months were 54.7% (trial, n=133/243) and 46.1% (non-trial, n=368/799). At Months 22–24, median reductions in seizure frequency/28 days were 66.7% (n=17/129; trial) and 95.0% (n=34/200; non-trial); 50% responder rates were 64.7% (n=11/17) and 82.4% (n=28/34), respectively. Treatment-emergent adverse events (TEAEs) occurred in 52.2% (trial, n=223/427) and 37.7% (non-trial, n=481/1276) of patients; most common was dizziness (11.5% vs 6.0%).

Efficacy was observed at both trial and non-trial sites. Differences in retention rates, titration schedules, and TEAE incidence may reflect prior experience gained by sites involved in previous perampanel clinical trials. Differences in patient numbers at trial and non-trial sites should be considered when interpreting these data.

Funding: Eisai Inc.