Additional Results from Two Randomized, Placebo-Controlled Trials of Stiripentol in Dravet Syndrome Highlight a Rapid Antiseizure Efficacy with Longer Seizure-Free Periods.

Abstract

The efficacy of stiripentol in Dravet syndrome children was evidenced in two randomized, double-blind, placebo-controlled, phase 3 studies, namely STICLO France (October 1996-August 1998) and STICLO Italy (April 1999-October 2000), but data were not fully exploited at the time. This post-hoc analysis used additional information, notably collected during the open-label extension (OLE) month, or reported by caregivers in individual diaries, to evaluate new outcomes. Overall, 64 patients were included (31 in the placebo group, 33 in the stiripentol group) of whom 34 (53.1%) were female. Patients' mean and median (25%; 75%) age were 9.2years (range 3.0-20.7years) and 8.7years (6.0; 12.1) respectively. At the end of the double-blind treatment period, 72% of the patients in the stiripentol group had a≥50% decrease in generalized tonic-clonic seizure (GTCS) frequency, versus 7% in the placebo group (P<0.001), 56% had a profound (≥75%) decrease versus 3% in the placebo group (P<0.001), and 38% were free of GTCS, but none in the placebo group (P<0.001). The onset of stiripentol efficacy was rapid, significant from the fourth day of treatment onwards. The median longest period of consecutive days with no GTCS was 32days in the stiripentol group compared to 8.5days in the placebo group (P<0.001). Further to the switch to the third month OLE, an 80.2% decrease in seizure frequency from baseline was observed in patients previously receiving placebo, while no change in efficacy was observed in those already on stiripentol. Adverse events were more frequent in the stiripentol group, with significantly more episodes of somnolence, anorexia, and weight decrease than in the placebo group. Altogether these new analyses of the STICLO data reinforce the evidence for a remarkable efficacy of stiripentol in Dravet syndrome, with a demonstrated rapid onset of action and sustained response, as also evidenced in further post-randomized trials.