Elizabeth Thiele, MD, PhDElizabeth Thiele, MD, PhD
Cannabidiol (CBD) is officially under review by the FDA for the treatment of seizures associated with tuberous sclerosis complex (TSC), according to an announcement from GW Pharmaceuticals.

The drug, marketed as Epidiolex, has received priority review and has been assigned a PDUFA date of July 31, 2020. Epidiolex was previously approved in June 2018 for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome in patients age 2 and older.

“We are pleased with the FDA’s acceptance of our Epidiolex sNDA filing with Priority Review, an action that underscores the unmet need for new treatment options for patients with TSC, a rare and severe childhood-onset disease,” said Justin Gover, GW’s chief executive officer, in a statement. “More than 60% of individuals with TSC do not achieve seizure control with standard antiepileptic drug treatments…we look forward to working with the FDA during the review process to expand the Epidiolex product label for use in TSC.”

At the 2019 American Epilepsy Society Annual Meeting, lead investigator Elizabeth Thiele, MD, PhD, director of pediatric epilepsy and the Herscot Center for Tuberous Sclerosis Complex at Massachusetts General Hospital, presented the findings from the GWPCARE6 trial, which examined 2 doses of cannabidiol versus placebo in patients with TSC.
 
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The phase 3 trial included 224 patients, 75 of whom were randomly assigned to receive 25 mg CBD, 73 to 50 mg CBD, and 76 to placebo. Median baseline monthly TSC-associated seizure frequency was between 54 and 61 across the 3 groups. Notably, patients in the trial had previously tried and discontinued treatment with a median of 4 antiepileptic drugs and were currently taking a mean of 3, the most common of which were valproate (45%), vigabatrin (33%), levetiracetam (29%), and clobazam (27%).

Compared with placebo (22%), 36% of patients in the 25 mg group and 40% in the 50 mg group experienced a ≥50% reduction in seizures. In addition, 48% of patients in both treatment groups reported a significantly greater reduction in total seizure frequency compared with placebo (27%; P = .0013 and P = .0018, respectively).

Notably, caregivers reported an overall improvement in 69% of those patients in the 25 mg group (odds ratio [OR], 2.25; P = .0074) and 62% of those in the 50 mg group (OR, 1.77; = .0580) compared with 40% of those in the placebo group.

Although adverse events (AEs) were common, most were mild to moderate in severity. The most common included diarrhea (25 mg: 31%; 50 mg: 56%; placebo: 25%), decreased appetite (25 mg: 20%; 50 mg: 23%; placebo: 12%), and somnolence (25 mg: 13%; 50 mg: 26%; placebo: 9%).

Discontinuation of treatment due to AEs occurred in 11% of the 25 mg group, 14% of the 50 mg group, and 3% of placebo patients. As well, 12% of the 25 mg patients (n = 9) and 25% of the 50 mg patients (n = 18) had elevated liver enzymes. Of those, 81% were also taking valproate.

“The higher dose wasn’t way more effective than the lower dose, and that suggests that, for the majority of patients, the lower dose should be effective,” Thiele, who is also professor of neurology at Harvard Medical School, told NeurologyLive in an interview. “I think that’s good because a lower dose of medication usually means better tolerability.”
REFERENCES
1. GW Pharmaceuticals and Greenwich Biosciences announce FDA acceptance of sNDA filing with priority review for Epidiolex® (cannabidiol) in the treatment of seizures associated with tuberous sclerosis complex [news release]. Carlsbad CA: GW Pharmaceuticals. March 31, 2020. Accessed April 1, 2020. biospace.com/article/releases/gw-pharmaceuticals-and-greenwich-biosciences-announce-fda-acceptance-of-snda-filing-with-priority-review-for-epidiolex-cannabidiol-in-the-treatment-of-seizures-associated-with-tuberous-sclerosis-complexpdufa-date-of-july-31-2020/
2. Thiele E, Wong M. Cannabidiol (CBD) treatment in patients with seizures associated with tuberous sclerosis complex: a randomized, double-blind, placebo-controlled phase 3 trial (GWPCARE6). Presented at: 2019 American Epilepsy Society Annual Meeting. December 7–10, 2019; Baltimore, Maryland. Abstract 1.293.