Real‐world effectiveness of highly purified cannabidiol in epilepsy associated with 15q11.2‐q13.1 duplication and deletion syndromes: A multicenter study

This multicenter retrospective study evaluated the effectiveness and safety of highly purified cannabidiol (CBD) in 22 patients with 15q11.2-q13.1 duplication or deletion syndromes (15q-DDS), including 12 with 15q duplication syndrome (dup15q) and 10 with Angelman syndrome (AS). Median (interquartile range [IQR]) age at CBD initiation was 14.5 (10-22.5) years, with a median (IQR) follow-up of 21 (14-33) months. All dup15q and two AS patients presented with a Lennox-Gastaut phenotype. At last observation, mean seizure reduction was 55.7% (95% confidence interval 38.7-72.7), with 63.6% patients achieving ≥50% reduction, 40.9% achieving ≥75% reduction, and 18.2% achieving seizure freedom. Tonic seizures in dup15q and myoclonic seizures in AS showed the most notable reductions. EEG improvement was observed in 7/16 patients, with marked improvement observed in two dup15q patients. Clinical improvement on the Clinical Global Impression-Improvement scale was reported in 72.7%, alongside nonseizure benefits such as improved sleep, behavior, and attention in a subset of patients. CBD was well tolerated; no patient discontinued CBD due to side effects alone, and retention at last visit was 81.8%. These findings suggest that CBD may provide clinically meaningful benefit in patients with 15q-DDS, including seizure reduction and improvements in sleep, behavior, and attention in selected cases. PLAIN LANGUAGE SUMMARY: Epilepsy secondary to 15q11.2-q13.1 duplication or deletion syndromes (15q-DDS) is often severe, making daily life difficult for patients and their families. In this study, treatment with highly purified cannabidiol (CBD) reduced seizures in many patients with 15q-DDS. CBD was generally well tolerated, and caregivers also reported improvements in sleep, behavior, and attention in a number of cases. Overall, these findings suggest that CBD may be a helpful treatment option for people with 15q-DDS.