Zogenix scores second late-stage study success for ZX008 in Dravet syndrome
Zogenix reported Thursday that a second Phase III study of the experimental drug ZX008 (low-dose fenfluramine hydrochloride) for the treatment of children and young adults with Dravet syndrome met its primary endpoint, as well as all key secondary goals. The company, whose shares jumped as much as 26 percent on the news, reaffirmed that it remains on track to submit regulatory filings for the drug in the EU and US during the fourth quarter.
In Study 1504, 87 patients with Dravet syndrome were randomised to treatment with ZX008 or placebo, both in combination with a stable background regimen of stiripentol plus other antiepileptic drugs. The main goal of the study was the change in convulsive seizure frequency versus placebo, while secondary endpoints included seizure frequency and longest seizure-free interval.
Top-line results showed that for the primary goal, patients taking ZX008 achieved a 54.7 percent greater reduction in mean monthly convulsive seizures versus placebo. Zogenix added that the median reduction in monthly convulsive seizure frequency was 62.7 percent in the ZX008 group compared to 1.2 percent in placebo patients.
In addition, results illustrated that 53.5 percent of patients in the ZX008 group achieved 50-percent or greater reduction in seizure frequency, compared to 6.8 percent of placebo-treated patients. Meanwhile, the proportions of patients with at least 75-percent reductions in seizure frequencies in these groups were 32.6 percent and 2.3 percent, respectively. The company noted the median longest seizure-free interval in the ZX008 arm was 22 days, versus 13 days in the placebo arm.
Zogenix said that the serious adverse-event rates were 14 percent in the ZX008 arm and 15.9 percent for the placebo group. The drugmaker added that adverse events were consistent with those observed in Study 1, which results detailed in September last year showed that ZX008 significantly reduced convulsive seizures versus placebo in patients with Dravet syndrome.
"We are encouraged by that (strength of seizure reduction data) and believe our drug will be used fairly early during treatment," CEO Stephen Farr said.
Last month, GW Pharmaceuticals' Epidiolex (cannabidiol) was approved by the FDA for the treatment of seizures associated with Lennox-Gastaut syndrome or Dravet syndrome in children at least two years old, making it the first therapy authorised in the US for the two severe, childhood-onset epilepsies (for related analysis, see ViewPoints: FDA gives GW a wide berth with Epidiolex).
For further related analysis, read also ViewPoints: Zogenix rounds the bases with epilepsy candidate.