Lead author: Professor Helen Cross
In a paper published on Wednesday 4 March 2026 by Professor Helen Cross, President of our Medical Advisory Board, new data has been shared from Stoke Therapeutics’ phase 1/2 clinical trial of zorevunersen, a potential disease-modifying treatment for Dravet Syndrome.
The data shows that participants experienced a reduction in seizures of between 59% and 91% over 20 months on the treatment. The results also show, for the first time, the potential to reduce the impact of the condition on a child’s mental processes and behaviour. The children’s quality of life improved over a three-year period and most of the treatment’s side effects were mild.
These are very encouraging statistics and have generated excitement across the community.
It’s important to remember that a phase 1/2 trial is primarily designed to check safety and side effects of a treatment, and zorevunersen has been deemed safe.
Whilst the seizure reduction data is promising, we won’t have a full picture of how well it works across a larger group of people until the phase 3 trial is complete; this next stage is due to begin in the UK very soon and we will keep you updated as we learn more.
Read the full news story here.
We have included some Frequently Asked Questions below for those wanting to find out more.
FAQs
In a paper published by Professor Helen Cross, President of our Medical Advisory Board, new data has been shared from Stoke Therapeutics’ phase 1/2 clinical trial of zorevunersen, a potential disease-modifying treatment for Dravet Syndrome.
The data shows that participants experienced a reduction in seizures of between 59% and 91% over 20 months on the treatment. These are very encouraging statistics and have generated excitement across the community.
It’s important to remember that a phase 1/2 trial is primarily designed to check safety and side effects of a treatment, and zorevunersen has been deemed safe.
Whilst the seizure reduction data is promising, we won’t have a full picture of how well it works across a larger group of people until the phase 3 trial is complete; this next stage is due to begin in the UK very soon and we will keep you updated as we learn more.
Zorevunersen (produced by Stoke Therapeutics in collaboration with Biogen) works by tackling the underlying cause of the disease – a faulty gene.
Humans typically have two copies of the SCN1A gene and in most people with Dravet syndrome, one copy of this gene doesn’t produce enough of a protein for their nerve cells to function properly.
Zorevunersen works by increasing the levels of the protein produced by the healthy SCN1A gene, aiming to restore proper nerve-cell function. As it is targeting the underlying cause of Dravet Syndrome, zorevunersen aims to improve learning and behaviour, as well as seizure control.
So that zorevunersen can get into the brain, it is given via lumbar puncture (an injection into the spine).
Recruitment for phase 3 of this clinical trial is still open but there are very limited places and the criteria is restricted to certain types of patients in terms of age and seizure frequency. Talk to your care team if you would be interested in finding out more. Further details about this and other clinical trials are available here: Current Clinical Trials – Dravet Syndrome UK
The phase 3 trial will include Great Ormond Street Hospital, Sheffield Children’s Hospital and The Royal Hospital for Children in Glasgow
Even though this trial is beginning to enter phase 3 trials it is still likely to be several years away from potential routine NHS use. It must first complete phase three studies (estimated to be finished in late 2028), then be licensed by the UK regulator, and finally assessed for NHS funding.
The aim of the phase 1/2 trial is to determine the safety of a potential treatment. Over the course of this study, zorevunersen was generally well-tolerated. Cerebrospinal fluid protein elevations were the most common side effect, but no participants experienced symptoms of this. Some participants also had vomiting after the administration procedure, but this is a known side effect of lumbar punctures. One patient experienced a suspected unexpected serious adverse reaction following treatment, but the protocol was amended to prevent this happening again.
The phase 1/2 clinical trial included people up to the age of 18, so this potential treatment has never been tested in adults. Factors like years of seizures and medicines, plus how brains change as we get older, make it tricky to predict how well zorevunersen might work in adults.
However, other similar treatments for childhood conditions, like Spinraza for SMA, are given to adults too and have benefits like slowing decline and improving symptoms.
The only way to know for certain would be to have a clinical trial of zorevunersen in adults; Dravet Syndrome UK continues to advocate for this.
After repeated doses of zorevunersen, positive changes across five key areas of thinking skills and behaviour were seen. These improvements go against the usual pattern in Dravet Syndrome, where cognition and behaviour tend to stay the same or get worse over time.
No, therapies like zorevunersen are not a cure but disease-modifying treatments.
While they can improve different aspects of the condition, including seizures, cognition, and behaviour, they require repeated dosing and do not completely eliminate Dravet Syndrome or all its challenges; it is likely that people receiving treatments like zorevunersen will still have lifelong care needs. We won’t know their full impact until they’ve been trialled in more people over longer periods.