GW Pharmaceuticals plc, a biopharmaceutical company focused on discovering, developing and commercialising novel therapeutics from its proprietary cannabinoid product platform, announced that the US Food and Drug Administration (FDA) has granted Orphan Drug designation for cannabidiol (CBD) for the treatment of Tuberous Sclerosis Complex (TSC).

TSC is a rare genetic disorder, the most common symptom of which is epilepsy. Epilepsy occurs in around 80-90 per cent of TSC patients and is a significant cause of morbidity and mortality. TSC is the third orphan indication that GW is targeting within its Epidiolex (CBD) clinical development programme, which includes four phase 3 pivotal trials in Dravet syndrome and Lennox-Gastaut syndrome, both rare and catastrophic forms of childhood-onset epilepsy. On April 11, 2016, GW announced it has commenced a phase 3 clinical trial of Epidiolex as an adjunctive therapy for the treatment of seizures associated with TSC.

Under the Orphan Drug Act, the FDA may grant orphan drug designation to drugs intended to treat a rare disease or condition - generally a disease or condition that affects fewer than 200,000 individuals in the U.S. The first NDA applicant to receive FDA approval for a particular active moiety to treat a particular disease with FDA orphan drug designation is entitled to a seven-year exclusive marketing period for that drug and use, unless the applicant is unable to assure sufficient quantities of the drug or another applicant is able to demonstrate that its version of the drug is clinically superior.

TSC is a genetic disorder that causes non-malignant tumors to form in many different organs, with the brain and skin being the most commonly affected tissues. There are approximately 50,000 in the United States and nearly 1 million people worldwide estimated to have TSC1. Epilepsy is the most common presenting symptom in TSC and is also the most common medical disorder in TSC. Up to 80 to 90% of individuals with TSC will develop epilepsy during their lifetime, with onset typically in childhood. The majority of children with TSC have onset of seizures during the first year of life, and up to one third of children with TSC will develop infantile spasms. Almost all seizure types can be seen in individuals with TSC, including tonic, clonic, tonic-clonic, atonic, myoclonic, atypical absence, partial, and complex partial. The seizures are often severe, and up to two-thirds of TSC patients do not respond adequately to available medical therapies. There are significant co-morbidities associated with TSC including cognitive impairment, autism spectrum disorders, and neurobehavioral disorders in individuals with TSC. 2

Epidiolex, GW’s lead cannabinoid product candidate, is a liquid formulation of pure plant-derived CBD, which is in development for the treatment of a number of rare pediatric epilepsy disorders. GW has conducted extensive pre-clinical research of CBD in epilepsy since 2007. This research has shown that CBD has significant anti-epileptiform and anticonvulsant activity using a variety of in vitro and in vivo models and has the ability to treat seizures in acute animal models of epilepsy with significantly fewer side effects than existing anti-epileptic drugs. To date, GW has received Orphan Drug Designation from the US Food and Drug Administration (FDA) for Epidiolex in the treatment of Dravet syndrome, Lennox-Gastaut syndrome and TSC. Additionally, GW has received Fast Track Designation from the FDA and Orphan Designation from the European Medicines Agency for Epidiolex for the treatment of Dravet syndrome. GW is currently evaluating additional clinical development programmes in other orphan seizure disorders.