GW Pharmaceuticals has kicked off a Phase III trial investigating its cannabidiol Epidiolex as an adjunctive therapy for the treatment of seizures associated with the rare genetic disorder Tuberous Sclerosis Complex.

Epilepsy is the key symptom of the disease, occurring in around 80-90% of patients, and represents a significant cause of morbidity and mortality.

“Our decision to evaluate Epidiolex in TSC is based on findings from the physician-led Epidiolex expanded access program, which found that TSC patients reported reductions in seizure activity,” stated Justin Gover, GW’s Chief Executive Officer.

Recent safety and efficacy data on 10 patients diagnosed with TSC showed that the percentage those reporting a 50% or greater reduction in seizures were 50 percent, 50 percent, 40 percent, 60 percent and 66 percent at two, three, six, nine, and 12 months of treatment with Epidiolex, respectively. Side effects were seen in five patients (50%) and most were resolved with anti-epileptic drug or CBD dose adjustment.

The Phase III dose-ranging trial will compare the drug versus placebo over 16 weeks in around 200 patients, aged one to 65, to assess its safety and efficacy as an adjunctive antiepileptic treatment. The primary measure of this trial is the percentage change from baseline in seizure frequency during the treatment period, and several secondary outcome measures will be also analysed. 

TSC is the third indication that GW is targeting within its Epidiolex clinical development program, which includes four Phase III pivotal trials in Dravet syndrome and Lennox-Gastaut syndrome, both rare and catastrophic forms of childhood-onset epilepsy. 

Last month shares in the UK company rocketed 140 percent after a Phase III Dravet syndrome trial showed that Epidiolex significantly reduced convulsive seizures over the entire treatment period compared with placebo.