New cannabis-based epilepsy drug showing 'promise' in clinical trials on children

Epidiolex was developed for children with illnesses that resist other treatment

A marijuana plant (MARCEL VAN HOORN/AFP/Getty Images)

A new cannabis-based drug for children with severe epilepsy is showing “promising” signs in clinical trials.

Epidiolex is being tested on children with Dravet Syndrome and other forms of epilepsy that do not respond to existing drugs.

Its manufacturer, GW Pharmaceuticals, said most of the 60 children in the trials so far had seen the frequency of both “drop” and convulsive seizures fall.

The most common side effects were somnolence (sleepiness) and fatigue in a fifth and a tenth of patients respectively.

Dr Elizabeth Thiele, director of the Pediatric Epilepsy Program at Massachusetts General Hospital, said she was “very encouraged” by the preliminary results.

“I believe that Epidiolex has the potential to be an important advance in treatment for these treatment-resistant children and will likely have a significant role as a future therapy,” she added.

The drug, which does not have any intoxicating effects, is a liquid made of a purified cannabidiol extracted from marijuana plants grown under licence at a secret location in Britain.

The US Food and Drug Administration fast-tracked the drug’s status to allow the trials earlier this year and placebo-controlled clinical trials for Dravet Syndrome and Lennox-Gastaut Syndrome are due to start.

Both forms of epilepsy start in childhood and are difficult to treat.

Out of 151 patients in safety testing for the drug, 26 experienced serious adverse effects and two died, although GW Pharmaceuticals said independent investigations found they were unrelated to the trial.

The children in the study, with an average age of 11, were all receiving other treatment alongside the Epidiolex and two were removed from the study because of “adverse effects” and another four due to “a lack of clinical effect”.

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The patients are all between the ages of one and 18 with illnesses shown to be resistant to many or all of the anti-epilepsy treatments, including drugs and a ketogenic diets.

Maria Roberta Cilio, who is testing the drug at the Benioff Children’s Hospital in San Francisco, said studies on animals had showed cannabidiol works as an anticonvulsant.

“It’s important to get seizure control at any age but in children, uncontrolled seizures may impact brain and neurocognitive development, which can have an extraordinary effect on quality of life and contribute to progressive cognitive impairment,” she added.

“This trial is pioneering a new treatment for children with the most severe epilepsies, for whom nothing else works.

“But we are just at the beginning, combining experts in the field with a brave institution ready to take this on, and courageous patients looking for hope.”

Epidiolex has only been tested on American children so far but trials are expected to expand across Europe, including at Great Ormond Street Hospital in London.