Gene Therapy Cuts Epilepsy Seizures Over 90%
Three patients with drug-resistant epilepsy saw monthly seizures fall by more than 90% in an early-stage clinical trial reported in The New England Journal of Medicine.
Updated on Nov. 4, 2026 in Stroke
Researchers reported that three participants with drug-resistant epilepsy had seizures reduced by more than 90% after receiving experimental gene therapy delivered directly into brain tissue. The participants did not experience serious side effects.
Why it matters
The approach targets the small patch of brain tissue that generates seizures, offering a possible alternative for people who have developed resistance to at least two anti-seizure drugs. The sample is very small, so the results are preliminary.
The trial enrolled three patients who had been diagnosed with epilepsy 10-25 years earlier and had developed resistance to at least two anti-seizure drugs. Larger studies and longer follow-up are needed to confirm the reduction in seizures and assess durability.
The players
Yang Dai
Yang Dai is a neurosurgeon at Xuanwu Hospital of Capital Medical University in Beijing who led the study.
Xuanwu Hospital of Capital Medical University
Xuanwu Hospital of Capital Medical University is a major hospital in Beijing where the study was conducted.
The details
The gene therapy uses adeno-associated virus 9 to deliver a gene into neurons, producing a receptor that binds to clozapine. Clozapine then activates these receptors, reducing activity in the targeted neurons. All three participants had hippocampal sclerosis on one side of the hippocampus.
Timeline
Participants were diagnosed with epilepsy 10-25 years before enrollment.
Participants averaged at least two seizures per month in the three months before enrollment.
Results were published in The New England Journal of Medicine on November 4, 2026.
Roadmap
The results come from an early-stage gene therapy approach developed with the involvement of Focalis Bio, a Canterbury-based company. The study is a first step toward testing whether targeted gene delivery can offer an alternative for drug-resistant epilepsy.
For people with drug-resistant epilepsy, this approach remains experimental and is not yet available as a treatment. Patients should continue working with their neurologists on current options while larger studies are awaited.
The takeaway
Gene therapy has shown early promise in reducing seizures in a few patients with drug-resistant epilepsy. Its safety and effectiveness will need confirmation in larger trials before it can be considered a treatment option.
Further reading
For more on brain-related conditions, see our Stroke coverage.
