Abstract Details

Title Cenobamate Plasma Concentrations in Patients Reaching =50% or 100% Responder Rates for =12 Months: A Post-hoc Analysis

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S13 - Epilepsy/Clinical Neurophysiology (EEG): Antiseizure Medications (1:36 PM-1:48 PM)

Poster/Presentation
Number 004

Background Cenobamate is an antiseizure medication approved in the US for treatment of focal seizures. Approval was based on data from two phase 2 studies (C013 and C017) and a phase 3 safety study (C021). Plasma concentrations may help physicians evaluate compliance, breakthrough seizures, and side effects. Steady-state trough plasma concentrations from the phase 2 studies with cenobamate 200 mg/day indicated reference ranges of 11.3-18.7 µg/mL for ≥50% responders and 10.8-19.8 µg/mL for those who were seizure-free for ≥12 months.

Objective To report post-hoc results of steady-state trough plasma concentrations with cenobamate 200 mg/day from 10 US study sites of a phase 3 safety study (C021) in ≥50% responders and seizure-free patients.

Design/Methods

Patients with uncontrolled focal seizures taking stable doses of 1-3 ASMs were enrolled in C021. During titration, increasing doses of cenobamate were administered (12.5, 25, 50, 100, 150, and 200 mg/day) biweekly; further increases to 400 mg/day by 50-mg/day increments biweekly were allowed. Trough cenobamate plasma concentrations were assessed on Visit 9 (first maintenance phase visit) and mean values were calculated for ≥50% responders and those who were seizure-free for ≥12 months at data cut-off.

Results

240 patients were included in the post-hoc analysis and 177 remained on cenobamate at data cut-off. Of patients remaining on cenobamate, mean trough plasma concentration at Visit 9 was 15.1 µg/mL. Those who achieved a ≥50% responder rate during maintenance phase (n=158) had a mean cenobamate trough concentration of 15.2 µg/mL. Patients who were seizure-free for ≥12 months (mean 23.5 months; n=60), had a mean trough cenobamate plasma concentration of 14.5 µg/mL.

Conclusions In the current post-hoc analysis, patients who achieved 50% responder rates or who had zero seizures for ≥12 months at data cut-off with cenobamate 200 mg/day had trough cenobamate plasma concentrations that were consistent with those observed in the phase 2 studies.

Authors/Disclosures
William E. Rosenfeld, MD, FAAN (Comprehensive Epilepsy Care Center for Children and Adults) PRESENTER	The institution of Dr. Rosenfeld has received personal compensation in the range of $500,000-$999,999 for serving as a Consultant for SK Life Science. Dr. Rosenfeld has received personal compensation in the range of $100,000-$499,999 for serving on a Speakers Bureau for SK Life Science.
Stephen Greene (SK Life Science Inc)	Stephen Greene has received personal compensation for serving as an employee of SK Life Science, Inc.
Louis Ferrari	Louis Ferrari has received personal compensation for serving as an employee of SK Life science.