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.

Before it's here, it's on the Bloomberg Terminal. LEARN MORE