FDA grants Breakthrough Therapy Designation to Encoded Therapeutics’ ETX101 for SCN1A+ Dravet syndrome, supported by Phase 1/2 data showing durable seizure reduction and neurodevelopmental improvement.
Written By: Sana Khan BPharm
Reviewed By: Pharmacally Editorial Team
Encoded Therapeutics announced that the U.S. Food and Drug Administration has granted Breakthrough Therapy Designation to ETX101 for the treatment of SCN1A-positive Dravet syndrome. This designation adds to a strong set of regulatory recognitions already awarded to ETX101, including Regenerative Medicine Advanced Therapy (RMAT), Fast Track, Orphan Drug, and Rare Pediatric Disease Designations.
The FDA’s decision highlights the serious nature of Dravet syndrome and the ongoing need for treatments that move beyond symptom management to address the underlying disease biology.
Breakthrough Therapy Designation
Breakthrough Therapy Designation is intended to speed the development and review of investigational therapies for serious or life-threatening conditions when early clinical evidence suggests substantial improvement over existing treatments.
According to Encoded Therapeutics, data from its ongoing Phase 1/2 studies (NCT05419492) of ETX101 showed durable seizure reduction along with improvements in neurodevelopment following a single administration. Based on these findings, the company believes ETX101 has the potential to redefine the standard of care for patients with Dravet syndrome by targeting the root cause of the disease.
Salvador Rico, M.D., Ph.D., Chief Medical Officer of Encoded Therapeutics, stated that the designation reflects the FDA’s recognition of the urgent need for disease-modifying options in Dravet syndrome and emphasized the company’s commitment to continued collaboration with the agency to advance ETX101 as efficiently as possible.
With this designation, Encoded will receive more frequent and intensive guidance from the FDA, including involvement of senior reviewers, as well as eligibility for rolling and priority review of a future marketing application.
About ETX101
ETX101 is an investigational AAV9-based gene regulation therapy designed to increase expression of the SCN1A gene in inhibitory interneurons, with the goal of restoring sodium channel function.
By targeting this core disease mechanism, ETX101 aims to address the full spectrum of Dravet syndrome manifestations, including seizures, cognitive and communication impairment, behavioural challenges, and motor dysfunction. The therapy is administered as a single intracerebroventricular injection and is intended to provide long-term benefit.
In addition to Breakthrough Therapy Designation from the FDA, ETX101 has received RMAT, Fast Track, Rare Pediatric Disease, and Orphan Drug Designations in the United States, as well as Orphan Designation from the European Medicines Agency.
About Dravet Syndrome
Dravet syndrome is a severe genetic developmental and epileptic encephalopathy that begins in infancy and is most commonly caused by loss-of-function variants in the SCN1A gene. The condition is marked by frequent and prolonged seizures that are often resistant to treatment, along with significant cognitive, behavioural, and motor impairments.
Individuals with Dravet syndrome face a lifelong disease burden and an increased risk of premature mortality. Despite available therapies, current treatment options are largely symptomatic and do not address the underlying genetic cause of the disorder.
References
Encoded Therapeutics Announces U.S. FDA Breakthrough Therapy Designation Granted to ETX101 for the Treatment of Dravet Syndrome, 12 January 2026, https://encoded.com/press-releases/encoded-therapeutics-announces-u-s-fda-breakthrough-therapy-designation-granted-to-etx101-for-the-treatment-of-dravet-syndrome/
A Clinical Study to Evaluate the Safety and Efficacy of ETX101 in Infants and Children with SCN1A-Positive Dravet Syndrome (ENDEAVOR), ClinicalTrials.gov ID NCT05419492, https://clinicaltrials.gov/study/NCT05419492
Reboux R, Napuri S. The Difficult Journey of a Child with Dravet Syndrome: Perspectives from a Parent and the Neuropaediatrician. Neurol Ther. 2025 Dec;14(6):2261-2272. Epub 2025 Sep 19. PMID: 40971140; PMCID: PMC12623555. https://doi.org/10.1007/s40120-025-00826-7