- Shares in California-based Zogenix, Inc. surged higher by more than 120% Friday morning, buoyed by positive Phase 3 results from the biotech's lead and only drug candidate, a treatment for a rare form of epilepsy.
- Treatment with Zogenix's drug, known as ZX008, led to a significantly greater reduction in the monthly frequency of convulsive seizures compared to placebo for pediatric patients with Dravet syndrome.
- Zogenix still awaits data from its second Phase 3 trial studying ZX008, which if positive would support a filing for approval of the drug in the U.S. and Europe in the second half of next year.
Dravet syndrome usually manifests itself early in infancy as long-lasting, fever-related seizures. Unlike more common forms of epilepsy, infants and children with Dravet syndrome don't respond to standard anti-epileptic treatment. Continued seizures can result in cognitive and developmental impairment.
Zogenix's ZX008 is a low-dose form of fenfluramine hydrochloride, a drug that has been used to treat the condition for years under a compassionate use program in Belgium. The biotech hopes to win approval for its formulation of the drug in both the U.S. and Europe.
Friday's results put Zogenix one step closer to that goal.
Patients in the study were randomized to either a 0.8 mg/kg daily dose of ZX008, a 0.2 mg/kg daily dose or placebo. Treatment (or placebo) was given on top of anti-epileptic drugs for three and a half months.
The higher dose of ZX008 led to a 72.4% reduction from baseline in average monthly convulsive seizures, compared to a 17.4% reduction for those on placebo. Notably, ZX008 showed a strong dose-response relationship, with the lower dose also beating out placebo.
No unusual safety signals emerged compared to the known profile of fenfluramine. Almost all patients on ZX008 did, however, experience at least one treatment-emergent adverse event compared to 65% of those on placebo.
Results from Zogenix's second study are expected in the first half of next year, setting up a submission later in 2018.
Success could put Zogenix in competition with GW Pharma, whose cannabidiol-based drug Epidiolex has shown efficacy in treating Dravet syndrome as well. The London-based biopharma has started a rolling submission of Epidiolex to regulators for approval in both Dravet syndrome and Lennox-Gastaut syndrome.
Shares in GW Pharma fell by more than 10% when trading opened Friday morning, before paring back some of those losses — likely a reaction to the potential competitive threat from Zogenix.