Dravet Syndrome: New Therapy Reduces Seizures by Up to 91% in Children

A new experimental treatment is offering hope for children and families affected by Dravet syndrome, a rare and severe form of epilepsy. Initial trial results indicate that zorevunersen can significantly reduce seizure frequency – by as much as 91 percent in some young patients – and may too lessen the cognitive and behavioral challenges often associated with the condition. The findings, published in The New England Journal of Medicine, represent a potential turning point for a condition that has historically proven tricky to manage.

Understanding Dravet Syndrome and Its Impact

Dravet syndrome is a genetic disorder that begins in infancy, typically with prolonged seizures triggered by fever. These seizures often evolve into other types of epilepsy that are resistant to conventional medications. Beyond seizures, the condition can cause developmental delays, intellectual disability, speech difficulties, and movement problems. It affects approximately one in every 15,000 babies born in the UK, and carries a heightened risk of premature death. The impact on families is profound, often requiring constant vigilance and significantly impacting quality of life.

How Zorevunersen Works: Targeting the Genetic Root

Current epilepsy treatments often focus on managing symptoms, but zorevunersen aims to address the underlying cause of Dravet syndrome. The condition is frequently linked to a mutation in the SCN1A gene, which provides instructions for making a protein crucial for proper nerve cell function. Most people have two copies of this gene, but individuals with Dravet syndrome often have a faulty copy that doesn’t produce enough of the necessary protein.

Zorevunersen, developed by Stoke Therapeutics in collaboration with Biogen, is designed to increase production of the protein from the healthy copy of the SCN1A gene. The drug is administered via a lumbar puncture, allowing it to travel in spinal fluid to reach the brain where it’s needed. This approach differs from many existing epilepsy medications, which work by altering brain activity rather than correcting the genetic defect.

Trial Results: Safety and Efficacy in Early Studies

The initial clinical trial involved 81 children with Dravet syndrome, aged between two and 18, from both the United Kingdom and the United States. Before treatment, participants experienced an average of 17 seizures per month. Children received varying doses of zorevunersen, ranging from 10mg to 70mg, either as a single dose or in multiple doses over a three-month period.

The results showed a significant reduction in seizure frequency, with those receiving the 70mg dose experiencing a decrease of between 59 percent and 91 percent in seizures during the first 20 months of extension studies, compared to their seizure rates before treatment. Importantly, the drug was generally well-tolerated, with most side effects reported as mild. Researchers also observed improvements in quality of life among the children participating in the study.

Beyond Seizure Reduction: Potential Cognitive and Behavioral Benefits

While reducing seizure frequency is a primary goal in treating Dravet syndrome, the condition often has broader impacts on cognitive development, and behavior. The trial results suggest that zorevunersen may offer benefits in these areas as well. Researchers reported early evidence that the therapy could help mitigate some of the cognitive and behavioral challenges frequently associated with Dravet syndrome, though further investigation is needed to confirm these findings.

Participating Hospitals and Collaborative Research

The clinical trial was led by University College London (UCL) and Great Ormond Street Hospital (GOSH), with collaboration from several other institutions in the UK, including Sheffield Children’s Hospital, Evelina London Children’s Hospital, and The Royal Hospital for Children in Glasgow. Nineteen of the 81 participants were treated at UK hospitals. The study took place at GOSH’s National Institute of Health and Care Research’s Clinical Research Facility, a specialized center for pediatric clinical trials.

What Comes Next: Phase Three Trials and Future Outlook

The initial trial results are promising, but further research is essential to confirm the long-term safety and efficacy of zorevunersen. A larger Phase Three clinical trial is currently underway to evaluate the drug in a more extensive patient population. This phase will provide more robust data on the drug’s benefits and potential risks.

Professor Helen Cross, Director and Professor of Childhood Epilepsy at the UCL Institute of Child Health and an Honorary Consultant in Paediatric Neurology at GOSH, emphasized the potential impact of this treatment: “I regularly see patients with hard-to-treat genetic epilepsies with impacts that travel 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.”

Dravet Syndrome UK Chair of Trustees, Galia Wilson, echoed this sentiment, expressing excitement about the initial results and looking forward to the Phase Three trials to determine if the early promise translates into real hope for families affected by Dravet Syndrome.

For families like that of eight-year-old Freddie Truelove from Huddersfield, the impact of the trial has already been transformative. Freddie, who participated in the study, went from experiencing hundreds of seizures a day to just a few a week, allowing him to participate in activities his family previously thought impossible, such as swimming, skiing, and enjoying outdoor adventures. His mother, Lauren, shared that the treatment has “completely changed our lives,” giving them a future they never believed possible.