US regulators have assigned GW Pharmaceuticals’ cannabidiol Epidiolex orphan drug designation for the treatment of the rare genetic disorder Tuberous Sclerosis Complex.

TSC causes non-malignant tumours to form in many different organs, with the brain and skin being the most commonly affected tissues. There are around 50,000 in the US and nearly 1 million people worldwide estimated to have the condition.

The most common symptom of TSC is also epilepsy, which occurs in around 80%-90% of patients and represents a significant cause of morbidity and mortality.

Earlier this month, GW started a Phase III clinical trial of Epirdiolex in TSC patients after findings from the physician-led expanded access programme for the drug reported reductions in seizure activity.

Recent safety and efficacy data on 10 patients diagnosed with TSC showed that the percentage those reporting a 50 percent 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 percent) and most were resolved with anti-epileptic drug or CBD dose adjustment.

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