BOSTON – Adjunctive treatment with cannabidiol significantly reduced convulsive seizure frequency in Dravet syndrome patients in a randomized, double-blind, placebo-controlled trial.
Over a 14-week treatment period, including 2 weeks of titration and 12 weeks of maintenance, convulsive seizure frequency in 61 treated children and adolescents decreased from a median of 12.4 to 5.9 per month (median reduction of 39%), compared with a decrease from a median of 14.9 to 14.1 per month (median reduction of 13%) in 59 patients who received placebo, J. Helen Cross, MD, reported at the annual meeting of the American Academy of Neurology.
The proportion of patients with at least a 50% reduction in convulsive seizures was 42.6% with cannabidiol vs. 27.1% with placebo (odds ratio, 2.0), but this difference did not reach statistical significance, said Dr. Cross of the University College London Great Ormond Street Institute of Child Health and the Great Ormond Street Hospital for Children NHS Trust, London.
In a video interview, Dr. Cross discussed the findings and the importance of improving seizure control in patients with Dravet syndrome, a rare infantile-onset developmental and epileptic encephalopathy with very poor prognosis for long-term seizure control and neurodevelopmental outcomes.
Participants in the study (GWPCARE1) had a mean age of 10 years, but nearly a third were younger than 6 years. All had Dravet syndrome and drug-resistant seizures; the median number of antiepilepsy drugs previously tried was four, and the median number being used was three. Those randomized to the treatment group received cannabidiol oral solution up to 20 mg/kg per day.
Adverse events were common, occurring in 93.4% and 74.6% of treatment group and placebo group patients, respectively. But adverse events reported in the treatment group were mild or moderate in 84% of patients, and treatment was generally well tolerated.
“These are very complex patients with a high seizure burden... and therefore, to have another medication that looks as if it can be of benefit is really very exciting for this population,” Dr. Cross said, noting that cannabidiol was also shown in other studies presented at the AAN meeting (GWPCARE3 and GWPCARE4) to reduce seizure frequency in patients with Lennox-Gastaut syndrome.
GW Research sponsored the study. Dr. Cross is a member of the advisory boards for Eisai, GW Pharmaceuticals, Shire, and Zogenix.