British biotech company, GW Pharmaceuticals, came one step closer to getting its experimental cannabis-derived childhood epilepsy drug, Epidiolex, approved after completing a third late-stage trial.

GW’s CEO, Justin Gover, said in an interview with CNBC that children participating in the trial had previously tried 10 other anti-epileptic drugs but were still having up to three seizures a day.

“The impact that we have had that we have shown today is a hugely important potential breakthrough in the treatment of the condition called Lennox-Gastaut syndrome,” Gover said. Lennox-Gastaut syndrome is a rare and severe form of epilepsy that begins in childhood.

GW Pharma, based in the England, grows its own cannabis plants for research.

“The positive outcome in this second trial of Epidiolex in patients with Lennox-Gastaut syndrome demonstrates the effectiveness of this product in this particularly difficult to treat, childhood-onset epilepsy,” said Dr. Orrin Devinsky, of New York University Langone Medical Center’s Comprehensive Epilepsy Center, and principal investigator in the trial.

The results of the trial showed “high statistical significance,” which means the treatment was extremely effective in helping these patients.

The trial supports two earlier late-stage clinical studies, one in children with Lennox-Gastaut and one in patients with Dravet syndrome, another form of epilepsy—both of which demonstrated equally promising results. There are currently no FDA-approved treatments for Dravet syndrome.

“The unusual feature of this program is that we are developing the drug for two different types of epilepsy in parallel, and we have agreement from FDA to make one submission for the drug in two different indications,” Gover told the Telegraph. “That is unusual.”

This latest news puts GW Pharmaceuticals on track to file a new drug application with the FDA in the first half of 2017.

As to be expected, GW’s stock soared more than 17 percent after the announcement.