PHILADELPHIA—Additional data on the outcomes of children and young adults with treatment-resistant epilepsy who received open-label treatment with cannabidiol reinforce signals of safety and efficacy for the investigational drug, researchers said at the 69th Annual Meeting of the American Epilepsy Society.
Orrin Devinsky, MD, of New York University Langone Medical Center’s Comprehensive Epilepsy Center, and colleagues shared data for 261 patients (mean age, 11.8) who enrolled in an expanded-access program to receive Epidiolex, a liquid form of cannabidiol developed by GW Pharmaceuticals. The latest presentation includes twice as many patients as were reported in April. Safety data for 313 patients, including 52 patients who had not yet received 12 weeks of treatment or who withdrew from treatment, also were presented.
Patients in the program had various types of severe epilepsy, including Dravet syndrome (17% of patients) and Lennox-Gastaut syndrome (15% of patients). In all cases, cannabidiol was added to patients’ current antiepileptic drug regimens.
After 12 weeks of treatment, there was a 45% median reduction in total seizures across all patients, and the effect was maintained at 36 weeks. In addition, 27% of patients experienced a 50% or greater reduction in seizures, and 9% of all patients were seizure-free after 12 weeks of treatment.
Cannabidiol was well tolerated, with 4% of patients withdrawing due to side effects. Adverse events that occurred in 10% or more patients included somnolence (23% of patients), diarrhea (23%), fatigue (17%), decreased appetite (17%), convulsions (17%), and vomiting (10%). Most adverse events were mild or moderate and transient, the researchers said. Twelve percent of patients withdrew from treatment due to lack of clinical effect. Serious adverse events in 16 patients were deemed possibly related to treatment, including altered liver enzymes (four patients), status epilepticus/convulsion (four patients), diarrhea (four patients), decreased weight (three patients), and thrombocytopenia (one patient).
Among all patients, clobazam cotherapy was associated with a higher rate of treatment response, although this effect was not seen in the Dravet syndrome or Lennox-Gastaut syndrome groups, said the investigators.
The response rates in treatment-resistant patients that were seen in the expanded-access program support the likelihood that cannabidiol may help some patients, said Dr. Devinsky. Controlled studies are needed to confirm the results, he said. Results from four phase III trials in patients with Dravet syndrome and in patients with Lennox-Gastaut syndrome are expected in 2016. One trial in patients with Dravet syndrome already is complete. Investigators plan to complete an analysis of the results by the end of February, Dr. Devinsky said.
—Jake Remaly