Long-term cenobamate safe for patients with treatment-resistant focal seizures

Long-term use of cenobamate in the adjunctive setting appears to be safe and tolerable in the treatment of refractory focal seizures among patients taking up to three antiseizure medications (ASMs), according to the results of the open-label extension (OLE) of the YKP3089C013 study.

The 12-week randomized study examined the effect of adjunctive cenobamate treatment in adult patients with uncontrolled focal seizures. Of the 149 patients who underwent the double-blind treatment, 85 (57 percent) participated in the OLE phase.

During the OLE, dose adjustments of cenobamate and concomitant ASMs were allowed. The median duration of treatment with cenobamate was 6.8 years (range, 6.4–7.8), with the median modal daily dose being 200 mg (range, 50–400).

The probability of treatment continuation was 73 percent at year 1, 67 percent at year 2, 63 percent at year 3, 61 percent at year 4, 60 percent at year 5, and 59 percent at year 6. Among the 107 patients who continued at year 1, the probability of continuing treatment at years 2–5 was 92 percent, 87 percent, 83 percent, and 82 percent, respectively.

The most common reasons for discontinuation were patient withdrawal (n=29, 19.5 percent), adverse event (n=15, 10.1 percent), and lack of efficacy (n=8, 5.4 percent).

Treatment-emergent adverse events (TEAEs) that resulted in treatment withdrawal were fatigue (1.3 percent, 2/149), ataxia (1.3 percent, 2/149), and memory impairment or amnesia (1.3 percent, 2/149). Dizziness (32.9 percent, 49/149) was the most frequently reported TEAE, followed by headache (26.8 percent, 40/149) and somnolence (21.5 percent, 32/149). These events were primarily mild or moderate in severity.