Abstracts

Rationale: Perampanel (PER) is a once-daily oral anti-seizure medication (ASM) for focal onset seizures (FOS) and generalized tonic-clonic seizures (GTCS). In the USA and Japan, PER is approved as monotherapy and adjunctive therapy for FOS, with/without focal to bilateral tonic-clonic seizures (FBTCS), in patients aged ≥ 4 years, and as adjunctive treatment of GTCS in patients aged ≥ 12 years. Since limited real-world data on the long-term efficacy of PER monotherapy are available, the PORTABLE study, an observational, multicenter, prospective study to assess the long-term efficacy and safety of PER first-line monotherapy in patients aged ≥ 4 years with FOS, with/without FBTCS, during routine clinical care in Japan, was conducted.

Methods: Patients with new-onset/recurrent epilepsy with FOS starting treatment with PER monotherapy were enrolled. All patient signed an informed consent. The observation period was up to 30 months. During the COVID-19 period, the research was carried out as a semi-virtual clinical study, and the digital technology of eConsent, ePRO (Patient Reported Outcome) was incorporated, which obviated the need for the participants to visit the facility. Also, subjects who showed a tendency for sleep disorder prior to study inclusion and agreed the sleep assessments took objective sleep assessments using a wearable device that made assessment in the home possible. The study was carried out as a multi-institutional collaboration of 15 facilities in Japan. The primary endpoint was the rate of seizure freedom at 24 months, and the secondary endpoints were the rates of seizure freedom at 6, 12, 18, and 30 months, the rate of retention of PER, and QOL. In addition, safety was evaluated based on the number of adverse events reported.

Results: Sixty-one patients (mean age 38 years old, 25 were woman) were enrolled between May 2021 and June 2022, and interim 12-month results obtained to date are reported. Sleep assessments could be taken in two patients, and one case for which interim data could be collected was reported here. The mean baseline seizure frequency was 2.9 times/month. The starting dose of PER was < 2 mg in 26.2% and 2 mg for 72.1%. The modal dose (the dose used for the longest period during observation) was median 2.0 mg/mean 3.1 mg. At 12 months, the seizure-freedom rate was 67.4%, the retention rate was 70.5% and QOL was stable. The most common adverse reactions were somnolence (14.8%), dizziness (11.5%), and psychiatric disorders such as irritability (8.2%). In addition, subgroup analyses were conducted by age (< 18 years, 18-64 years, and ≥65 years), starting dose (< 2 mg and 2 mg), and actual dose (< 4 mg and ≥4 mg). One patient showed improvement in sleep evaluation measurements (total sleep time, sleep efficiency, etc.).

Conclusions: The study confirmed PER’s efficacy and safety as a first-line therapy in patients with epilepsy who are naïve to antiepileptic drugs at 12 months of treatment, suggesting that PER may also be a treatment option for patients with new-onset/recurrent epilepsy.

Funding: This abstract was funded by Eisai Co., LTd.