Therapeutic efficacy of Stiripentol

The effectiveness of Stiripentol for the treatment of seizures associated with Dravet syndrome was established in 2 multicenter placebo-controlled double-blind randomized studies (Study 1 and Study 2), conducted according to similar protocols. To be enrolled in either study, patients were required to be 3 years to less than 18 years of age, to have Dravet syndrome (ILAE classification of epilepsy, 1989), and to be inadequately controlled on clobazam and valproate, with at least 4 generalized clonic or tonic-clonic seizures per month despite optimized therapy.

Eligible patients were enrolled in a 1-month baseline period during which they continued to receive their optimized antiepileptic treatment. Following this 1-month baseline, patients were randomly allocated to receive either Stiripentol (fixed dose of 50 mg/kg/day in divided doses with no dose titration) or placebo, added to their treatment with clobazam and valproate. Duration of double-blind treatment was 2 months. The frequency of generalized clonic or tonic-clonic seizures during the study was recorded by patients and/or their caregivers, using a diary. Although patients with Dravet syndrome have several different types of seizures, only generalized clonic or tonic-clonic seizures were recorded, as other seizure types can be difficult to recognize by patients and/or their caregivers as seizures.

The primary efficacy endpoint for both studies was the responder rate. A responder was defined as a patient who experienced a greater than 50% decrease in the frequency (per 30 days) of generalized clonic or tonic-clonic seizures during the double-blind treatment period compared tothe 4-week baseline period (i.e., placebo run-in). The mean change from baseline in frequency of generalized clonic or tonic clonic seizures was also evaluated.

In Study 1 (n=41), 21 patients were randomized to Stiripentol, and 20 patients to placebo. In Study 2 (n=23), 12 patients were randomized to Stiripentol, and 11 patients to placebo. In both studies, the demographic and baseline clinical characteristics were similar between the treatment groups.

Table 5 summarizes the results of the primary endpoint for Stiripentol in each study.