Zogenix has revealed top-line results from a second late-stage trial of its investigational Dravet syndrome drug ZX008, showing a significant reduction in seizures.

The study met its primary endpoint, demonstrating that the drug is superior to placebo as adjunctive therapy to stiripentol in the treatment of children and young adults with the condition, a difficult-to-treat form of childhood-onset epilepsy.

Patients taking ZX008 (low-dose fenfluramine hydrochloride) achieved a 54.7 percent greater reduction in mean monthly convulsive seizures compared to placebo, while the median reduction in monthly convulsive seizure frequency was 62.7 percent in the ZX008 group compared to 1.2 percent in placebo patients.

The drug also showed statistically significant improvement versus placebo in both key secondary measures, including patients with clinically meaningful reductions (>50 percent) in seizure frequency and longest seizure-free interval, the firm noted.

More than 90 percent of patients with Dravet syndrome have multiple seizures per day, which puts them at constant risk for falls and injury.

“These impressive study results show the significant impact the addition of ZX008 made in reducing the burden of convulsive seizures for patients who are not adequately controlled using stiripentol, the standard of care for the treatment of Dravet syndrome in Europe,” said Professor Rima Nabbout, department of Pediatric Neurology, Reference Center for Rare Epilepsies, Necker Enfants Malades Hospital, and Principal Investigator of Study 1504.

“If approved, ZX008 has the potential to be a transformative treatment for Dravet syndrome, a rare and serious form of epilepsy with few available treatment options.”

Also of note, the drug was generally well-tolerated in this study, with the adverse events consistent with those observed in the other Phase III trial published last year, and the known safety profile of fenfluramine.

The incidence of side effects was similar in both the treatment and placebo groups, with 97.7 percent of patients receiving ZX008 experiencing at least one treatment emergent adverse event compared to 95.5 percent of patients in the placebo group, the most common being decreased appetite, diarrhea, pyrexia, fatigue, and nasopharyngitis.

ZX008 is designated as an orphan drug in both the US and Europe, and has received Breakthrough Therapy designation in the US for the treatment of Dravet syndrome.