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Phase 3 of ZX008 in Dravet Syndrome Meets Primary and Secondary Endpoints

DECEMBER 04, 2017
Mathew Shanley
Positive safety and efficacy data from Zogenix’s Study 1 trial were released this morning, exhibiting ZX008's (low-dose fenfluramine hydrochloride) ability to achieve a clinically meaningful benefit to Dravet Syndrome patients.

Top-line results from the pivotal Phase 3 clinical trial of the investigational drug in refractory epilepsy were previously reported in September, and additional data were presented at the 71st American Epilepsy Society (AES) Annual Meeting last week.

Dravet syndrome is a rare pediatric epilepsy disorder characterized by a wide variety of seizure types, and is often associated with a high mortality rate. It almost always begins in the first year of life in an otherwise healthy infant. Those affected can also experience developmental delays, and, at present, there aren’t any approved orphan drugs to treat the condition.

The new data showed the odds of achieving a clinically meaningful (≥50%) or substantial (≥75%) reduction in convulsive seizure frequency were 29- and 50-times higher, respectively, among patients treated with ZX008 0.8 mg/kg/day than in patients treated with placebo.

“These new data demonstrate Dravet syndrome patients treated with ZX008 achieved a clinically meaningful reduction in seizure frequency. If approved, ZX008 could play an important role in changing the treatment paradigm for patients and their families whose lives have been greatly impacted by the lack of effective seizure control provided by current treatment options,” said Lieven Lagae, M.D., Ph.D., Professor at the University of Leuven, Belgium, Head of the Pediatric Neurology Department and Director of the Childhood Epilepsy Program at the University of Leuven Hospitals, and Principal Investigator of Study 1 in Europe in a press release.

Study 1 met its primary objective in demonstrating that ZX008, as an adjunctive therapy, is superior to placebo when dosed at 0.8 mg/kg/day based on change in the frequency of convulsive seizures between the 6-week baseline observation period and the 14-week treatment period (p<0.001).

Patients taking ZX008at that dose achieved a nearly 64% reduction in mean monthly convulsive seizures compared to placebo. Monthly, the median percent reduction in convulsive seizure frequency was 72.4% among ZX008 patients compared to 17.4% in placebo patients.

The same analysis showed that 0.2 mg/kg/day of ZX008 was also superior to placebo, as patients taking that dose achieved a reduction in mean monthly convulsive seizures of 33.7% compared to placebo, allowing a key secondary endpoint to be met.

Additionally, both doses of ZX008 demonstrated statistically significant improvements compared to placebo in other key secondary measures, including the proportion of patients with clinically meaningful reductions in seizure frequency and longest seizure-free interval.

The most common treatment-related adverse events (AEs) in Study 1 included diarrhea, vomiting, fatigue, pyrexia, nasopharynges, upper respiratory tract infection, fall, weight loss, decreased appetite, lethargy, seizure, and somnolence.

In January 2016, Zogenix received Fast Track Designation from the U.S. Food and Drug Administration (FDA) for ZX008 for the treatment of seizures associated with Dravet Syndrome. Last week, Zogenix announced that the first patient was enrolled in a Phase 3 clinical trial of ZX008 for Lennox-Gastaut syndrome (LGS).

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