Efficacy of cenobamate for uncontrolled focal seizures in patients with previous epilepsy-related surgery: Post hoc analysis of a phase 3, multicenter, open-label study

Objective: This post hoc analysis of 10 US study sites from a long-term open-label phase 3 study of adjunctive cenobamate evaluated the efficacy of cenobamate in patients with prior epilepsy-related surgery. Methods: Patients with uncontrolled focal seizures despite taking stable doses of 1–3 concomitant antiseizure medications (ASMs) received increasing doses of cenobamate (12.5, 25, 50, 100, 150, 200 mg/day) at 2-week intervals over 12 weeks (target dose, 200 mg/day). Further increases up to 400 mg/day using biweekly 50-mg/day increments were allowed during the maintenance phase. Dose adjustments of cenobamate and concomitant ASMs were allowed. Data were assessed until the last clinic visit on or after September 1, 2019. Results: Of the 240 eligible patients, 85 had prior epilepsy-related surgery and 155 were nonsurgical patients. Baseline focal seizure frequency per 28 days was numerically higher among prior surgery (mean=25.9/median=4.1/range=0.3–562.3) versus nonsurgical (mean=13.8/median=2.4/range=0.2–534.2) patients. Among all patients, 100 % seizure reduction ≥ 12 months at any consecutive month interval occurred in 30.6 % (26/85) prior surgery and 39.4 % (61/155; p > 0.05) nonsurgical patients (cenobamate treatment median duration=32.9 months). Among the 177 patients still receiving cenobamate at the data cutoff, 29.2 % (19/65) of prior surgery and 36.6 % (41/112; p > 0.05) of nonsurgical patients had 100 % seizure reduction ≥ 12 months at the data cutoff. Cenobamate was well tolerated. Conclusions: This post hoc analysis supports the efficacy of cenobamate in patients with refractory focal seizures despite prior surgery. These findings suggest cenobamate may be considered early in the treatment regimen, including, in some patients, before surgery is considered.