FDA Grants Breakthrough Therapy Designation to Potential Dravet Syndrome Therapy

The FDA has granted Breakthrough Therapy Designation to Zogenix’s drug ZX008, a therapy intended to treat seizures associated with Dravet syndrome.

The FDA’s Breakthrough Therapy Designation is based on the results from Zogenix’s first global Phase 3 trial of ZX008, Study 1. The trial met the primary efficacy endpoint, as well as key secondary efficacy endpoints.

An estimated 16,000 to 29,000 patients live with Dravet syndrome, a life-threatening form of epilepsy that typically presents during the first year of life as frequent fever-related seizures.

Patients with Dravet syndrome often have a mutation in SCN1A gene, resulting in an improper function of brain cells. The underlying cause of the condition, however, varies from patient to patient.

At around a patient’s second year of life, intellectual development begins to deteriorate, leading to a lack of coordination, poor development of language, orthopedic conditions, hyperactivity, sleeping difficulties, chronic infections and difficulty relating to others.

Between 15% to 25% of patients with Dravet syndrome have a family history of epilepsy or febrile seizures. These patients require constant care, and approximately 10% to 20% of patients will pass away before 10 years of age due to sudden unexpected death in epilepsy (SUDEP).

Seizures associated with Dravet syndrome are unable to be treated with therapies indicated for epilepsy, and there are currently no approved treatments for Dravet syndrome seizures.

ZX008 is a low-dose fenfluramine liquid solution that decreases the number of seizures patients with Dravet syndrome experience. In September 2017, positive Phase 3 results proved ZX008 to be a superior adjunctive therapy.

The primary efficacy measure of the study found that a ZX008 dosage of 0.8 mg/kg/day caused a 72.4% median monthly reduction of seizures in patients. In patients taking ZX008 0.2 mg/kg/day saw a 33.7% monthly average decrease of convulsions.

“We are very pleased that the FDA has granted Breakthrough Therapy Designation based on the efficacy and safety results from Study 1 reported in fall of 2017,” said Gail M. Farfel, Ph.D., Chief Development Officer of Zogenix, in a press release. “We look forward to working closely with the FDA as we conclude our Phase 3 clinical program in Dravet syndrome, a rare and catastrophic form of childhood epilepsy.”

ZX008 has been granted Orphan Drug Designation in the U.S. and Europe for Dravet syndrome and Lennox-Gastaut syndrome indications. The drug has also received Fast Track designation by the FDA for the treatment of Dravet syndrome.

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