GW Pharmaceuticals plc, a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics from its proprietary cannabinoid product platform, has commenced the second of two phase 3 clinical trials of Epidiolex (cannabidiol or CBD) for the treatment of Lennox-Gastaut syndrome (LGS), a rare and severe form of childhood-onset epilepsy.

During 2014, GW received Orphan Drug designation from the US Food and Drug Administration (FDA) for Epidiolex for the treatment of LGS. GW anticipates that top-line data from this trial will be available in the first quarter of 2016.

“With the commencement of this trial, GW’s pivotal programme of four phase 3 trials for Epidiolex in Dravet syndrome and Lennox-Gastaut syndrome is now fully underway,” stated Justin Gover, GW’s chief executive officer.

“The long-term prognosis for Lennox-Gastaut syndrome patients is poor in terms of seizure control and cognitive development and patients typically have continued seizure activity into adulthood. GW is committed to bringing Epidiolex to patients as a new option to address this significant unmet need.”

The LGS phase 3 pivotal trial programme comprises two studies, both of which comprise a randomized, double-blind, 14-week comparison of Epidiolex versus placebo. The treatment period consists of a two-week titration period followed by a 12-week maintenance period. One phase 3 trial has two arms of 50 patients; 20mg/kg and placebo, whereas the second study also includes a low dose treatment arm, and therefore includes a total of 150 patients. The primary measure of efficacy in both trials will be the comparison between Epidiolex and placebo in the percentage change from baseline in number of drop seizures. Several additional efficacy and safety secondary outcome measures will be analysed. Following their participation in the studies, all patients are eligible to receive Epidiolex under a long term open label extension study.

In addition to the Epidiolex clinical programmes in LGS and Dravet syndrome, GW has also announced plans to develop Epidiolex in a third target indication, Tuberous Sclerosis Complex, a rare pediatric genetic disorder, the most common symptom of which is epilepsy. GW expects to commence a TSC phase 3 clinical programme in the second half of 2015.

LGS usually begins before 4 years of age, and can be caused by a number of conditions, including brain malformations, severe head injuries, central nervous system infections, and inherited degenerative or metabolic conditions. In 30 to 35 per cent of patients, no cause can be found. Patients commonly have frequent seizures of a wide variety, including convulsive, atonic seizures (brief loss of muscle tone and consciousness, causing abrupt falls). Drug resistance is one of the main features of LGS. Most children with LGS experience some degree of impaired intellectual functioning or information processing, as well as developmental delays and behavioural disturbances. It is estimated that there are approximately 14,000-18,500 patients with LGS in the United States and 23,000-31,000 patients with LGS in Europe.