Rare Disease Report

GW Pharmaceuticals Provides Update on Their Cannabidiol Product To Treat Dravet Syndrome

OCTOBER 15, 2014
James Radke

Cannabis can cure children of seizures!  As we have written before, that makes for a nice TED talk and CNN special.  However, the data examining the efficacy of cannabis on seizure control is mostly anecdotal and therefore, of limited interest to the FDA.
One company not relying on anecdotal evidence is GW pharmaceuticals who are conducting properly designed clinical trials with their investigational cannabidiol product, Epidiolex which is an oral liquid formulation that contains plant-derived cannabidiol for the treatment of children with Dravet syndrome or Lennox-Gastaut syndrome – two rare conditions in which children are besieged with epileptic seizures at a very young age.  Cannabidiol is a non-psychoactive molecule from the cannabis plant.
This week, GW Pharmaceuticals provided an update on their clinical programs during their Research Day. The full webcast can be found by clicking here.   The presentation included a number of conditions that Epidiolex may be effective for. Below is the data presented that focused on Dravet syndrome.

Dravel Syndrome

Dravet syndrome or severe myoclonic epilepsy of infancy (SMEI), is a severe form of epilepsy.  It appears during the first year of life with frequent febrile seizures.  Later, other types of seizures typically arise, including myoclonus (involuntary muscle spasms).  Status epilepticus – a state of continuous seizure requiring emergency medical care – also may occur.  Children with Dravet syndrome typically experience poor development of language and motor skills, hyperactivity, and difficulty relating to others. 

Anticonvulsants may reduce seizures in Dravet syndrome. A ketogenic diet (high fat, low carbohydrates) may be beneficial in some patients. At present, no orphan drugs are approved for Dravet syndrome.

During the Research Day webcast, GW Pharmaceuticals did not provide details on the clinical study design but they did state that in 12 children with Dravet syndrome (average age 8 yrs) given Epidiolex, the efficacy in reducing seizure activity was promising. Below is the efficacy data from the 12 children with Dravet syndrome provided by the company during their webcast.
 Response Week 1-4
Week 5-8
Week 9-12
Week 13-16
Median reduction
in seizue activity
-72% -62% -51% -56%
 ≥50% responders 58% 67% 58% 56%
 ≥70% responders 50% 42% 42% 33%
 ≥90% responders 33% 33% 25% 22%
 Seizure free 33% 33% 25% 22%

Similar reductions were also observed in 12 children with ‘drop’ seizures; 4 of which had Lennox-Gastaut syndrome.  

Adverse Events

Safety data were made available on 151 patients (58 patients with 12 weeks treatment effect data plus 93 additional patients for whom 12 week treatment effect data is not yet available) and represents approximately 50 patient-years of exposure to Epidiolex. The most common adverse events (occurring in 10% or more patients and resulting from all causes) were somnolence (19% of patients) and  fatigue (11% of patients).

Future Studies

The protocol for the first Phase 2/3 Dravet syndrome clinical trial is finalized and the trial is on track to commence this month. An additional Phase 3 Dravet syndrome clinical trial is expected to begin in early 2015. GW also expects to start two Phase 3 trials in Lennox-Gastaut syndrome in the first quarter of 2015.

The first Phase 2/3 trial is designed as a two-part randomized double-blind, placebo-controlled parallel group dose escalation, safety, tolerability, pharmacokinetic and efficacy trial of single and multiple doses of Epidiolex to treat Dravet syndrome in children who are being treated with other anti-epileptic drugs. Part one comprises the pharmacokinetic and dose-finding elements of the trial in a total of 30 patients over a 3 week treatment period. Part two is a placebo-controlled safety and efficacy evaluation of Epidiolex over a 3 month treatment period in a total of 80 patients.

Image of cannabis leaf courtesy wikimedia commons.
Image of Dravet syndrome clinical trial program from GW Pharmaceuticals’ webcast.

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