Sustainability of seizure reduction and seizure control with adjunctive cenobamate: Post hoc analysis of a phase 3, open‐label study.

Objective: In this post hoc analysis of a subset of patients from a long‐term, open‐label phase 3 study, we assessed ≥50%, ≥75%, ≥90%, and 100% seizure reduction and sustainability of these responses with cenobamate using a time‐to‐event analytical approach. Methods: Of 240 patients with uncontrolled focal seizures who had adequate seizure data available, 214 completed the 12‐week titration phase and received ≥1 dose of cenobamate in the maintenance phase (max dose 400 mg/day) and were included in this post hoc analysis. Among patients who met an initial given seizure‐reduction level (≥50%, ≥75%, ≥90%, or 100%), sustainability of that response was measured using a time‐to‐event methodology. An event was defined as the occurrence of a study visit at which the seizure frequency during the interval since the prior study visit exceeded the initially attained reduction level. Study visits during the maintenance phase occurred at 3‐month intervals. Results: Of the 214 patients analyzed, 188 (88%), 177 (83%), 160 (75%), and 145 (68%) met ≥50%, ≥75%, ≥90%, and 100% seizure‐reduction responses, respectively, for at least one study visit interval during the maintenance phase. The median (95% confidence interval [CI]) time to first visit without a ≥50% seizure reduction was not reached by 30 months of follow‐up (53% of patients maintained their initial ≥50% seizure reduction). Median (95% CI) time to first visit without sustaining the initial ≥75%, ≥90%, or 100% seizure reduction was 13.0 (7.5–21.9) months, 7.5 (5.4–11.6) months, and 7.0 (5.3–10.4) months, respectively. Among the 145 patients who had 100% seizure reduction during at least one study visit, 22% remained seizure‐free for at least 30 months and 63% had ≤3 study visits with seizures. Significance: Adjunctive treatment with cenobamate led to sustained seizure reductions during the maintenance phase of the phase 3 safety study. [ABSTRACT FROM AUTHOR]