Cannabidiol Therapy Reduces Seizure Frequency in Dravet Syndrome

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The drug has already been given Orphan Drug and Fast Track Designation for the treatment of Dravey syndrome.

Investigators have announced positive results for the first phase 3 clinical trial of GW Pharmaceutical’s cannabidiol therapy Epidiolex in patients with Dravet syndrome.

The unpublished results mark a milestone for Epidiolex, which has already received Orphan Drug Designation and Fast Track Designation from the US FDA for the treatment of Dravet syndrome.

“The results of this Epidiolex pivotal trial are important and exciting as they represent the first placebo-controlled evidence to support the safety and efficacy of pharmaceutical cannabidiol in children with Dravet syndrome, one of the most severe and difficult-to-treat types of epilepsy,” said principal investigator Orrin Devinsky, MD, of New York University Langone Medical Center’s Comprehensive Epilepsy Center. “These data demonstrate that Epidiolex delivers clinically important reductions in seizure frequency together with an acceptable safety and tolerability profile, providing the epilepsy community with the prospect of an appropriately standardized and tested pharmaceutical formulation of cannabidiol being made available by prescription in the future.”

Results from a previous open-label, multicenter study were presented at the 2015 annual meeting of the American Epilepsy Society. 

The pivotal phase 3 study included 120 patients randomized to either 20 mg/day of Epidiolex (n=61) or placebo (n=59) as adjunctive therapy to current antiepileptic treatment regimens. Average patient age was 10 years, with 30% of participants under age 6. Median baseline seizure frequency was 13 per month. Primary endpoint was percent change in monthly seizure frequency during the 14-233k treatment period compared to 4-week baseline observation period.

Following the treatment period, participants taking Epidiolex experienced a statistically significant 39% mean reduction in seizure frequency compared to 13% in the placebo group (P=-0.01). The treatment difference between Epidiolex and placebo became evident in the first month and was sustained throughout the treatment period.

Epidiolex was well tolerated overall. Common adverse events included somnolence, diarrhea, decreased appetite, fatigue, pyrexia, vomiting, lethargy, upper respiratory tract infection, and convulsion. Eighty-four percent of those that reported an adverse event reported is as mild or moderate. Ten patients on Epidiolex experienced a serious adverse event compared to 3 taking placebo, and 8 patients in the treatment group discontinued treatment due to adverse events compared to 1 patient in the placebo group.

“In light of this positive data, we will now request a pre-NDA meeting with the FDA to discuss our proposed regulatory submission,” GW CEO Justin Grover said in a statement.

A second phase 3 trial in patients with Dravet syndrome is currently recruiting 150 patients, and a phase 3 trial in patients with Lennox-Gastaut syndrome is underway.