GW Pharmaceuticals has kicked off a late-stage trial assessing its investigational cannabidiol Epidiolex in patients with Dravet syndrome, a rare and treatment-resistant form of childhood epilepsy for which there is no approved treatment in the US.

The Phase III trial is the second part of a two-part randomised, double-blind, placebo-controlled parallel group safety, tolerability, pharmacokinetic and efficacy study of the drug in children with the syndrome who are being treated with other anti-epileptic drugs. 

Part one - the pharmacokinetic and dose-finding elements of the trial - completed earlier this year. Part two is a 14-week comparison of Epidiolex versus placebo in a total of 100 patients to assess the drug’s safety and efficacy as an adjunctive anti-epileptic treatment. 

Top-line data should be available by the end of this year, with a view of submitting a New Drug Application in the US mid-2016, the British drugmaker said.