Antiepileptic Efficacy Study of GWP42003-P in Children and Young Adults With Dravet Syndrome (GWPCARE1)

GWEP1332 Part B recruited an entirely new group of participants than GWEP1332 Part A. Participants who failed the entry criteria for Part A were eligible to take part in Part B. Part B was a 1:1 randomized, double-blind, placebo-controlled, 14-week comparison of GWP42003-P versus placebo. The aim of Part B was to assess the antiepileptic efficacy of GWP42003-P as an adjunctive antiepileptic treatment compared with placebo, with respect to the percentage change from baseline during the treatment period of the study in convulsive seizure frequency in children and young adults. Following the establishment of initial eligibility and baseline measurements, participants entered Part B and began a 28-day baseline observation period. Eligible participants were then randomized to receive either GWP42003-P or placebo on a 1:1 basis and titrated up to the target dose that was identified in Part A (up to 20 milligrams \[mg\] per kilogram \[kg\] per day), which was confirmed following completion of Part A by an independent Data Safety Monitoring Committee who reviewed unblinded safety and pharmacokinetic data from Part A. Participants received investigational medicinal product for 14 weeks, consisting of a titration period followed by a 12-week maintenance period. Efficacy and safety were monitored at various clinic visits and via telephone. After 14 weeks of treatment, all participants were offered the option of entering an open label extension (OLE) study. Entry was within seven days of the final treatment visit. Participants who did not immediately enter the OLE study commenced a down-titration taper period lasting up to 10 days. The taper period was interrupted if the participant wished to enter the open label extension study within the seven-day timeframe. For participants who opted not to enter the OLE study, a follow-up telephone call was made 28 days after the end of dosing and weekly safety telephone calls were made during the 28-day follow-up period.