Cannabis-based Epidiolex helps some epilepsy sufferers

May 9, 2019 | Disease

Melanie senior

Epilepsy is characterized by recurrent, unprovoked seizures. These result from disturbances to the brain’s normal patterns of electrical impulses.  A seizure may last a few seconds or a few minutes, causing changes in movement, behavior, feeling or awareness.

Injury to the brain is one of the most common causes of epilepsy, but for many of the estimated 65 million epilepsy sufferers worldwide, the cause remains unknown. Most cases are adequately treated with one or more of the dozen or so drugs on the market, which include UCB’s Keppra (leveteracitam) and Vimpat (lacosamide) and GlaxoSmithKline’s Lamictal (lamotrigine). Generic carbamazepine and formulations of valproic acid are also widely used.

The challenge in treating epilepsy is two-fold. The first issue, common to many areas of medicine, is diagnosing the disease and finding the right treatment for the right patient. A diagnosis of epilepsy occurs when a person has experienced two or more unprovoked seizures over 24 hours apart. But often the condition is not picked up. Even when it is, our lack of understanding of the disease’s precise causes in each individual, and of how some of the available treatments actually work, means patients often have to try out multiple medications one after the other.

Key opinion leaders in the field report that only 70% of patients fully respond to therapy and are freed from seizures.

A second area of unmet need in epilepsy is among the rarer forms of the disease, many among children, that are highly resistant to existing drugs. These include Lennox-Gastaut Syndrome (LGS), a severe form of childhood-onset epilepsy characterized by multiple seizures, cognitive dysfunction and with a very poor prognosis, and Dravet Syndrome.

A new category of epilepsy treatment, derived from cannabis, was approved in the US in 2018 for both these rarer forms of the condition. GW Pharmaceuticals’ Epidiolex (cannabidiol) is the first prescription medication formulation of highly-purified, plant-derived cannabidiol – a molecule found in the cannabis plant (but not the one responsible for highs associated with recreational use of cannabis). The drug was found in Phase III trials to reduce the frequency of seizures among patients taking it alongside their standard medications, relative to those taking only standard treatments.

Epidiolex is currently under review in Europe, and is also in Phase III trials for seizures associated with tuberous sclerosis complex (TSC). TSC is a rare, multi-system genetic disease that causes benign tumors to grow in the brain and other vital organs, and is closely associated with epilepsy.

Cenobamate is another promising anti-epileptic drug candidate, whose approval submission has just been accepted by the US FDA.  Developed by Korean company SK Life Science, the molecule showed promising efficacy results in Phase III trials of adults with partial-onset seizures. As is the case for several approved epilepsy treatments, cenobamate’s mechanism of action is not completely understood, and trials also revealed some safety issues. These may well prove surmountable, though, given unmet need among the estimated third of epilepsy sufferers whose seizures remain uncontrolled.