To report safety for the full follow-up and efficacy through 156 weeks of CBD treatment in an OLE (NCT02544750).

Safety and efficacy of add-on CBD in TSC was demonstrated in a phase 3 randomized controlled trial (RCT; GWPCARE6 [NCT02544763]).

Patients who completed GWPCARE6 RCT were enrolled to receive CBD (Epidiolex^®; 100 mg/mL oral solution), starting dose 25 mg/kg/d with titration up to maximum 50 mg/kg/d. Primary endpoint: safety. Secondary endpoints: percentage change in TSC-associated (countable focal and generalized) seizures, responder rates, and Subject/Caregiver Global Impression of Change (S/CGIC).

Of 201 RCT completers, 199 (99%) entered OLE. At baseline, median (range) age was 10.7 years (1.1–56.8) and number of ASMs was 3 (0–5). Most common concomitant ASMs were valproate (43%), vigabatrin (37%), and clobazam (35%). Baseline median (Q1, Q3) monthly TSC-associated seizure frequency: 57 (28, 109). Thirty-four patients (17%) completed treatment; most common reason for withdrawal was transition to commercial product (93 [56%]). Median (range) treatment time: 631 days (18–1462). Mean (SD) modal dose: 28 mg/kg/d (9). AEs incidence: 96% of patients, serious AEs incidence: 28%; discontinuation because of an AE: 9%. Most common AEs: diarrhea (47%), seizures (30%), pyrexia (24%), and decreased appetite (24%). Overall, 7% of patients had elevation in ALT levels and 5% in AST levels. There was 1 death due to cardiopulmonary failure, deemed not treatment related. Median percentage reduction in TSC-associated seizures (12-week windows through 156 weeks): 53%–90%. Seizure responder rates (≥50%, ≥75%, and 100%) ranged from 52%–78%, 29%–69%, and 6%–31% across 12-week windows through 156 weeks. Improvements on S/CGIC were reported by 89% and 93% of subjects/caregivers at 52 and 104 weeks.

Add-on CBD treatment was well tolerated and produced sustained reductions in TSC-associated seizures for up to 156 wks in patients treated in OLE.