Experience of perampanel monotherapy beyond initial titration to achieve seizure freedom in patients with focal-onset seizures with newly diagnosed or currently untreated recurrent epilepsy: A post hoc analysis of the open-label Study 342 (FREEDOM).

Objective: This post hoc analysis evaluated whether continued treatment with perampanel monotherapy beyond initial titration may be appropriate for patients with focal-onset seizures (FOS) with currently untreated epilepsy to achieve seizure freedom with an effective dose.

Methods: Study 342 (NCT03201900; FREEDOM) is a single-arm, open-label, Phase III study of perampanel monotherapy. Patients aged ≥12 years with untreated FOS received perampanel 4 mg/d in a 32-week Treatment Phase (6-week Titration and 26-week Maintenance Periods); in case of seizure(s) during Maintenance Period, patients could enter a 30-week Treatment Phase (4-week Titration and 26-week Maintenance Periods) to be up-titrated to perampanel 8 mg/d. The primary endpoint was seizure-freedom rate during Maintenance Period in the modified Intent-to-Treat (mITT) Analysis Set (patients who had ≥1 post-dose efficacy measurement during Maintenance Period); safety was monitored. This analysis of 4-mg/d efficacy data assessed the proportion of patients achieving seizure freedom during the Maintenance Period (responders) relative to patients with an early/later response (depending on seizure status during the Titration Period).

Results: In the mITT population (n = 73), 46 patients were 4-mg/d responders; of whom, 37 (80.4%) were early responders and nine (19.6%) were later responders. The mean (standard deviation) percent reductions in FOS frequency from baseline at the end of the 4-mg/d Titration Period were 100.0% (0.0%; early responders) and 46.3% (97.3%; later responders). Among the 27 4-mg/d nonresponders, nine (33.3%) patients who had an early response experienced seizure(s) during the subsequent 4-mg/d Maintenance Period. Safety outcomes were similar, regardless of responder status, without new safety concerns.

Significance: Some patients with untreated FOS may benefit from continued treatment beyond initial titration of perampanel monotherapy to achieve seizure freedom, suggesting that it may not be appropriate to make treatment decisions to discontinue or switch from perampanel monotherapy solely based on seizure response before an effective dose has been reached.