(Bloomberg) -- GW Pharmaceuticals Plc surged in early U.S. trading after the drugmaker said its experimental, cannabis- based treatment for a rare form of epilepsy reduced seizures in a human trial.

The company’s American depositary receipts more than doubled to $85.50 at 8:03 a.m. in New York. Other companies with cannabis-based products also rose, including Zynerba Pharmaceuticals Inc., which gained 52 percent.

Epidiolex, a marijuana extract, reduced convulsive seizures in children with Dravet syndrome in a late-stage trial involving 120 individuals, GW said in a statement. The treatment reduced monthly convulsive seizures by 39 percent in the group receiving treatment, while a control group saw seizures fall 13 percent, GW said.

GW’s ADRs had tumbled 45 percent this year through Friday.

To contact the reporter on this story: Zachary Tracer in New York at ztracer1@bloomberg.net To contact the editors responsible for this story: Drew Armstrong at darmstrong17@bloomberg.net Cecile Daurat