New Therapy Reduces Dravet Syndrome Seizures By Over 90 Percent
According to the Epilepsy Foundation, an estimated 3.4 million Americans live with epilepsy, a chronic neurological disorder characterized by abnormal electrical activity in the brain that causes sudden and recurrent seizures, including about 470,000 children living with an epilepsy diagnosis. While there is no long-term, universal cure for epilepsy, various treatments allow 70 percent of people to lead seizure-free lives.
In 2026, University College London and Great Ormond Street Hospital collaborated on an international clinical trial involving an experimental therapy for children living with a severe and hard-to-treat form of the disorder. The results were highly promising, suggesting that the treatment is both safe and effective, with the ability to greatly improve the health and lives of affected individuals.
Published in The New England Journal of Medicine, the study focused on young patients living with Dravet syndrome, a rare, incurable genetic epileptic condition that starts in infancy. Individuals living with Dravet syndrome frequently experience extended seizures, generally triggered by fever. Over the course of the study, researchers determined that an investigational drug, zorevunersen, could reduce seizure occurrences by more than 90 percent. Furthermore, the study indicated that regular zorevunersen may reduce the impact of Dravet syndrome on cognitive function and behavior. Children involved in the three-year study enjoyed an overall improvement in quality of life, while the reported side effects were typically mild.
Due to the rarity and severity of Dravet syndrome, seizures associated with the disorder have long proven resistant to treatments and difficult to control. In addition to seizures, children living with the disorder encounter long-term neurodevelopmental challenges, including feeding problems in infancy, difficulty moving, and an elevated risk of premature death. In the past, treatment options remained limited, with available medications failing to completely control seizures, and none of the approved therapies mitigating the cognitive and behavioral complications.
Developed by Stoke Therapeutics, in collaboration with Biogen, zorevunersen addresses the underlying cause of Dravet syndrome by targeting the faulty gene associated with the disorder. Normal genetic profiles consist of two copies of the SCN1A gene, but in individuals living with Dravet syndrome, one of the copies is defective and unable to produce the key protein Nav1.1 which plays a key role in controlling electrical activity in the brain. Zorevunersen increases Nav1.1 production in the healthy copy of the gene, boosting overall protein levels towards normal levels and restoring function in key cells including inhibitory interneurons which act as breaks or regulators of electrical signaling.
The study involved 81 individuals between the ages of two and 18 years from the United States and the United Kingdom, with a focus on safety and tolerability, in addition to the drug's ability to decrease seizure frequency while improving cognitive function, behavior, and quality of life. Individuals averaged 17 seizures per month before taking the drug. Researchers provided zorevunersen in different dosages, and patients saw seizures reduced by between 59 and 91 percent. Following the success of the initial study, researchers have launched a larger Phase Three trial.
According to lead author Professor Helen Cross, the director of childhood epilepsy at the UCL Institute of Child Health and an honorary consultant in pediatric neurology at Great Ormond Street Hospital, the 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."