This morning, USA-based CNS focused biotech firm Zogenix (Nasdaq: ZGNX) announced new positive efficacy and safety data from their pivotal Phase III clinical trial of ZX008 in Dravet syndrome.
The new Study 1 results 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 0.8mg/kg/day than in patients treated with placebo.
The data were presented at the American Epilepsy Society annual meeting presently taking place in Washington DC.
Despite the psoitive trial results, Zogenx’ shares fell 7.46% to $36.00 by mid-morning trading today.
The study also measured improvement on the Clinical Global Impression (CGI-C) rating. 55% of patients treated with ZX008 0.8mg/kg/day were rated by parents/caregivers as very much improved or much improved in overall condition on the CGI-C compared to 10% of the placebo group (p=0.001) and 62.5% of patients treated with ZX008 0.8mg/kg/day were rated by investigators as very much improved or much improved in overall condition on the CGI-C compared to 10% of the placebo group (p=0.001).
ZX008 is designated as an orphan drug in both the USA and Europe, and has received Fast Track designation in the USA for the treatment of Dravet syndrome.
“Dravet syndrome is a rare form of intractable epilepsy for which a significant unmet medical need currently exists,” said Lieven Lagae, 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. “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,” Dr Lagae added.
As previously reported, Study 1 met its primary objective of demonstrating that ZX008, at a dose of 0.8mg/kg/day, is superior to placebo as adjunctive therapy in the treatment of Dravet syndrome in children and young adults 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 ZX008 0.8 mg/kg/day achieved a 63.9% reduction in mean monthly convulsive seizures compared to placebo (p<0.001). The median percent reduction in monthly convulsive seizure frequency was 72.4% among ZX008 0.8 mg/kg/day patients, compared to 17.4% in placebo patients.
A key secondary endpoint was the same analysis for a comparison of ZX008 0.2mg/kg/day and placebo. Patients taking ZX008 0.2mg/kg/day achieved a reduction in mean monthly convulsive seizures of 33.7% compared to placebo (p=0.019). ZX008 0.8mg/kg/day and ZX008 0.2mg/kg/day also demonstrated statistically significant improvements versus placebo in additional key secondary measures, including the proportion of patients with clinically meaningful reductions in seizure frequency and longest seizure-free interval.
“Our confidence in the potential of ZX008 as an effective treatment for seizures associated with Dravet syndrome continues to strengthen with the new data showing that both caregivers and clinicians perceived patients’ overall condition to be very much or much improved following treatment with ZX008,” said Stephen Farr, president and chief executive of Zogenix, adding: “The overall data to date reinforce the potential of ZX008 to be an important new treatment for seizure control in children and young adults with Dravet syndrome, and we look forward to sharing top-line results from our second pivotal Phase III trial, Study 1504, in the second quarter of 2018.”