Cannabinoids for Epilepsy

Earlier last year, the most monumental approval of a cannabinoid occurred in the neurologic realm, specifically for the treatment of epilepsy. In June of 2018, the FDA approved Epidiolex for the treatment of a pair of pediatric epilepsies, namely Dravet and LGS. Epidiolex is a natural pharmaceutical-grade version of CBD and was able to demonstrate efficacy in a heavily pre-treated refractory population suffering from a debilitating disease (see Exhibit 7).

Exhibit 7:

Epidiolex trial data in Dravet and LGS Indication Doses tested Number of patients Average age Average number of AEDs currently prescribed Number of previously tried AEDs Median baseline seizure frequency Epidiolex seizure reduction Placebo seizure reduction p value Dropouts due to AEs Dravet 20mg/kg 120 10 3 4 13 convulsive seizures -39% (20mg/kg) -13% 0.0123 13% LGS Trial 1 20mg/kg 171 15 3 6 74 drop seizures -44% (20mg/kg) -22% 0.0135 14% LGS Trial 2 20mg/kg and 10mg/kg 225 16 3 7 85 drop seizures -42% (20mg/kg), -37% (10mg/kg) -17% 0.0047 (20mg/kg), 0.0016 (10mg/kg) 8% (20mg/kg), 1% (10mg/kg) Source: GW Pharmaceuticals

Dravet syndrome is an extremely malignant form of childhood epilepsy that typically presents itself within the first year of life with prolonged febrile and afebrile, generalized clonic or hemiclonic epileptic seizures in otherwise normally developing children. Around 10–14% of Dravet patients end up dying, typically around the age of six or seven.3 Besides the risk of death, by the time the children are teenagers they exhibit either severe or profound learning disabilities. In one study of 31 typical and borderline Dravet patients (14 were typical Dravet, 17 were borderline) who were followed until adulthood, 22.6% could speak no words at all, 29% could speak several words, 29% could make primitive conversation and 16.1% could make simple conversation and read to some extent. Only one (3.2%) with borderline Dravet could lead an independent life, although he developed psychosis.4 The incidence of Dravet ranges from 1:20,000 to 1:40,000 births, which suggests an overall disease prevalence of 5,500 patients in the US and 6,700 European patients.5

LGS, like Dravet, is a rare form of epilepsy, although it typically starts later in life, at between two and eight years of age vs six months for Dravet. As with Dravet, outcomes are extremely poor for these patients, with 90% becoming mentally handicapped with a progressive reduction in IQ. The mortality rate is high, although the exact percentage varies based on the study and ranges between 3% and 25%.6 Incidence estimates for LGS vary, but it accounts for approximately 2–5% of all childhood epilepsies. This suggests 16,000 pediatric patients with LGS in the US and 24,000 in Europe with prevalence potentially doubling if including adult LGS patients according to the LGS Foundation.

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