Novel seizure outcomes in patients with Lennox‐Gastaut syndrome: Post hoc analysis of seizure‐free days in rufinamide Study 303

OBJECTIVE: Drug development for patients with Lennox‐Gastaut syndrome (LGS) is based on clinical trials that use drop seizure counts. However, such counts do not assess total seizure burden and affect a patient's quality of life (QoL). In this post hoc analysis, we evaluated two novel seizure efficacy parameters related to QoL in pediatric patients with LGS, using seizure diary data from rufinamide Study 303 (NCT01405053). METHODS: Study 303 was a phase III, multicenter, randomized, controlled, open‐label study involving patients aged ≥1 to <4 years with inadequately controlled LGS. Patients were randomized 2:1 to receive add‐on therapy with rufinamide or any other approved antiseizure drug (ASD), in addition to their existing treatment of 1‐3 ASDs, across a 106‐week treatment phase. Seizure diaries, completed by parents or caregivers, recorded seizure occurrence, and were used in this post hoc analysis to evaluate two novel efficacy parameters comparing baseline vs postbaseline mean number of seizure‐free days and assessing time to reach the number of prerandomization seizures for patients receiving rufinamide or any other ASD. RESULTS: Patients received rufinamide (n = 25) or any other ASD (n = 12). For rufinamide, mean number of seizure‐free days was 42.2% greater postbaseline compared with baseline (P < 0.0001); only one rufinamide patient experienced a decrease in number of seizure‐free days postbaseline. Median time to reach the baseline number of seizures increased by 10.5 days for rufinamide and 0.5 days for the any‐other‐ASD group during the treatment phase, to 46.0 and 54.0 days, respectively. SIGNIFICANCE: Both of these novel and contrasting endpoints demonstrated potential improvements in seizure outcomes in patients receiving rufinamide postbaseline vs baseline. Although these parameters should be investigated in larger patient populations, our initial findings suggest that they could be applied as predefined primary endpoints for seizure assessment in future clinical trials for LGS drug development.