Dravet syndrome doesn't just take seizures. It takes time.
Children with this rare, severe genetic form of epilepsy typically experience their first seizure before their first birthday. What follows is a life shaped by constant neurological crisis — seizures that don't respond to most medications, frequent hospitalisations, profound cognitive and developmental delays, and in too many cases, sudden unexplained death in epilepsy. Families describe it as a relentless emergency that never truly ends.
For decades, the medical community could offer management. Not a solution. Not even close.
Results published in the New England Journal of Medicine this week suggest that may be changing.
Zorevunersen, an investigational drug developed by Ionis Pharmaceuticals in partnership with Biogen, has shown results in children with Dravet syndrome that researchers describe as potentially disease-modifying — a phrase that means the drug isn't just suppressing symptoms, but changing the underlying course of the illness.
The drug works by targeting the genetic root of the problem. Dravet syndrome is caused by mutations in the SCN1A gene, which encodes a sodium channel protein (NaV1.1) critical for normal brain function. Most patients have only one working copy of this gene. Zorevunersen is an antisense oligonucleotide — a precisely engineered molecule that boosts the production of functional NaV1.1 protein from that remaining good copy, essentially helping the brain compensate for the mutation.
In the Phase 1/2a trial, children receiving zorevunersen experienced up to 85% reduction in motor seizures at three months and up to 87% reduction sustained across 20 months of follow-up in the open-label extension. These are not modest improvements. For children who might have been having dozens of seizures a week, these numbers represent a fundamental transformation in daily life.
But the results go beyond seizure counts.
Significant improvements were also recorded in cognition, communication, motor skills, and quality of life — measures that reflect whether children are actually living better, not just seizing less. Expressive and receptive communication improved significantly in extension study patients for more than 36 months. The drug was well-tolerated, with most side effects rated mild to moderate.
Zorevunersen has received Breakthrough Therapy Designation from the FDA — the agency's signal that a drug addresses a serious condition and has demonstrated substantial improvement over existing therapies. A global Phase 3 trial (the EMPEROR study) is currently enrolling approximately 150 patients across the US, UK, and Japan, with data expected in mid-2027.
Dravet syndrome affects around 1 in 15,700 people. It is considered one of the most severe and treatment-resistant childhood epilepsies known to medicine. For families who have lived inside that statistic — measuring time in seizures, in hospital stays, in things their children cannot do — this week's data is something they have been waiting their whole lives to read.
Not just fewer seizures. Better thinking. Better talking. Better living.
That is what a disease-modifying therapy looks like. 💙