FDA clearance of GW Pharmaceuticals' Epidiolex to treat seizures marks first US approval of cannabinoid-derived drug

GW Pharmaceuticals on Monday said the FDA approved Epidiolex (cannabidiol) oral solution for the adjunctive treatment of seizures linked to Lennox-Gastaut syndrome or Dravet syndrome in patients at least two years old. The company noted that the therapy will be launched following US Drug Enforcement Administration scheduling, which is expected to occur in the next 90 days. CEO Justin Gover remarked that the approval marks "a historic milestone, offering patients and their families the first and only FDA-approved [cannabidiol] medicine to treat two severe, childhood-onset epilepsies." 

Approval was backed by safety and efficacy data from three late-stage trials involving a total of 516 patients. According to study data unveiled in 2016, the addition of Epidiolex to other antiepileptic drug regimens significantly reduced the frequency of convulsive seizures versus placebo in patients with Dravet syndrome. Meanwhile, the company has also reported data from one study of 225 patients with drug-resistant Lennox-Gastaut syndrome and another involving 171 such patients, showing that Epidiolex, in combination with current anti-epileptic drugs, was associated with significant declines in seizure frequency. 

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In April, an FDA advisory panel unanimously voted in favour of recommending approval of Epidiolex for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome or Dravet syndrome. Prior to the committee vote, FDA staff had concluded that the submitted data provided "substantial evidence" for the drug's efficacy. 

The agency said cannabidiol "does not cause intoxication or euphoria that comes from tetrahydrocannabinol (THC)," pointing out that it is THC "that is the primary psychoactive component of marijuana." FDA Commissioner Scott Gottlieb said "we'll continue to support rigorous scientific research on the potential medical uses of marijuana-derived products and work with product developers who are interested in bringing patients safe and effective, high quality products." However, he indicated that "we are prepared to take action when we see the illegal marketing of cannabidiol-containing products with serious, unproven medical claims."

The FDA awarded Epidiolex orphan drug status in 2014 for the treatment of Lennox-Gastaut syndrome. The drug was also granted fast track and orphan drug designations by the agency for use in patients with Dravet syndrome. 

Meanwhile, Epidiolex is also under review in Europe, where the therapy has been granted orphan drug status for the treatment of both Lennox-Gastaut syndrome and Dravet syndrome. GW Pharmaceuticals said a final decision regarding approval by European regulators is expected in the first quarter of next year.

In 2016, the FDA approved Insys Therapeutics' Syndros (dronabinol), a synthetic formulation of THC, for use in treating AIDS-related anorexia, as well as for nausea and vomiting associated with cancer chemotherapy. Insys recently initiated a Phase III trial of its cannabidiol oral solution for the treatment of infantile spasms. It is also testing its cannabidiol oral solution in mid-stage studies for refractory childhood absence epilepsy and Prader-Willi syndrome in paediatric patients.

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