Shares of GW Pharmaceuticals (GWPH) doubled on Monday with the much-anticipated release of positive data from a phase 3 study of Epidiolex, the company’s proprietary formulation of cannabidiol. The study tested Epidiolex in young patients with a severe and debilitating form of epilepsy called Dravet syndrome.
In conjunction with existing anti-epilepsy medications, patients receiving Epidiolex demonstrated a median reduction in monthly seizures of 39%, compared with a reduction of 13% in placebo-treated patients (p=0.01). Placebo response was a point of concern among investors leading into this data release given the historical confounding response in children.
On average, patients were already receiving 3 AEDs, and the average age of trial participants was 10 years. Patients had a median baseline convulsive seizure frequency per month of 13. The study randomized 120 patients to receive either Epidiolex 20mg/kg/day (n=61) or placebo (n=59), added to current anti-epileptic drugs.
Unanswered questions remain, however. Ten patients on Epidiolex experienced a serious adverse event (SAE), compared with three patients on placebo, and these SAEs went uncharacterized on a GW conference call Monday morning. Eight patients discontinued Epidiolex due to adverse events, compared with one patient on placebo.
GW is running a second phase 3 trial in Dravet syndrome, this one including 150 patients, which will be complete in the second half of this year. Two larger phase 3 studies of the drug in Lennox-Gastaut Syndrome, another rare and severe form of epilepsy, will be complete next quarter.
