Chasing GW, Zogenix scores a win in second Dravet phase 3

The chemical structure of the active ingredient in Zogenix's drug. (Klaus Hoffmeier/Public domain)

A second confirmatory phase 3 trial of Zogenix’s Dravet syndrome drug has met its primary endpoint. The efficacy hit and an unsurprising safety profile set the company up to compete with GW Pharmaceuticals in Dravet, sending Zogenix stock up 18% in premarket trading.

Dravet is a rare form of childhood epilepsy that causes seizures and later affects speech and walking. Zogenix thinks it can reduce the number of seizures children suffer through low, daily doses of the 5-HT reuptake inhibitor fenfluramine. That hypothesis received support from phase 3 data last year, and has now received a further boost from the results of a confirmatory study.

Investigators enrolled 87 children and young adults with Dravet and randomized them to take ZX008 or placebo. The trial linked ZX008 to a 55% reduction in mean monthly seizures, resulting in the trial hitting its primary endpoint with a p value of less than 0.001. Zogenix also racked up successes against secondary endpoints that looked at the proportion of patients to experience 50% and 75% reductions in their monthly seizures.

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The efficacy data are in line with the results from Zogenix’s first phase 3 trial, which established it as a viable competitor to GW’s Epidiolex. That competitive status could have been undermined by a bad safety profile, but Zogenix came through the second phase 3 unscathed. Notably, neither trial saw a case of cardiac valvulopathy or pulmonary hypertension, adverse events associated with an earlier product that featured the same active ingredient.

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With efficacy and safety data in hand, Zogenix is now preparing to file for approval.

“Based on these highly compelling top-line results from both of our pivotal studies, we are now focused on submitting applications for regulatory approvals in the U.S. and Europe in the fourth quarter of 2018,” Zogenix CEO Stephen Farr, Ph.D., said in a statement.

That timeline puts Zogenix behind GW, which won FDA approval last month and is working through the process in Europe. But, barring any surprises, ZX008 should offer near-term competition to GW.