Children with Dravet syndrome experienced up to 91 per cent fewer seizures after receiving a new medication, according to research published in The New England Journal of Medicine.
The study found that zorevunersen, developed by Stoke Therapeutics in collaboration with Biogen, was well tolerated by most patients and may also help improve cognition, behaviour and quality of life.
Dravet syndrome is a severe genetic condition that causes frequent, difficult-to-control seizures and long-term neurodevelopmental impairment.
The condition can also cause feeding difficulties and movement problems and is associated with a high risk of premature death.
Current treatments do not control seizures in most patients, and there are no approved medicines that address the cognitive and behavioural effects of the condition.
Zorevunersen is designed to target the underlying cause of Dravet syndrome.
Most people with the condition have one faulty copy of the SCN1A gene, which means their nerve cells do not produce enough of a protein needed to function properly.
The treatment works by increasing levels of the protein produced by the healthy copy of the SCN1A gene, with the aim of restoring nerve-cell function.
Researchers have now published results from an initial trial and extension studies involving 81 children with Dravet syndrome in the UK and US.
The early studies were designed primarily to assess the safety and tolerability of zorevunersen, while also evaluating its effects on seizures, cognition, behaviour and quality of life.
A Phase Three trial is now underway to further evaluate the treatment.
Lead author Professor Helen Cross, director and professor of childhood epilepsy at the UCL Great Ormond Street Institute of Child Health and honorary consultant in paediatric neurology at Great Ormond Street Hospital, said: “I regularly see patients with hard-to-treat genetic epilepsies with impacts that go beyond seizures and it’s heart-breaking when treatment options are limited.
“This new treatment could help children with Dravet syndrome lead much healthier and happier lives.
“Overall, our findings showed that zorevunersen is safe to use and well tolerated by most patients and supports further evaluation in the ongoing Phase Three study.”
The initial trial included 81 children aged two to 18, who had an average of 17 seizures a month before the study began.
Participants were given up to 70mg of zorevunersen by lumbar puncture, either as a single dose or with additional doses two or three months later over a six-month period.
Of those children, 75 went on to take part in extension studies and continued to receive the drug every four months.
Patients who received a 70mg dose in the initial phase saw seizures fall by between 59 per cent and 91 per cent over the first 20 months of the extension studies, compared with seizure levels before the trial began.
Nineteen participants were treated at UK hospitals, including Great Ormond Street Hospital, Sheffield Children’s Hospital, Evelina London Children’s Hospital and The Royal Hospital for Children in Glasgow.
At Great Ormond Street Hospital, the trial was conducted at the National Institute for Health and Care Research Clinical Research Facility, which supports children taking part in experimental trials.
Galia Wilson, chair of trustees at Dravet Syndrome UK, said: “We regularly see the devastating impact that this condition has on the lives of families. That’s why we’re so thrilled about these latest results from the initial zorevunersen clinical trials.
“We’re now looking forward to the Phase Three clinical trials taking place to see if the early promise we see here will translate into real hope for all those families currently affected by Dravet syndrome.”