Encoded's Gene Therapy Aims to Rewrite the Future of Dravet Syndrome

SOUTH SAN FRANCISCO, CA – April 27, 2026 – Clinical-stage biotech firm Encoded Therapeutics is poised to take center stage at a major scientific conference, where it will present highly anticipated data on a one-time gene therapy for a devastating form of childhood epilepsy. The company announced it will deliver an oral presentation on its lead candidate, ETX101, during the prestigious Presidential Symposium at the 29th Annual Meeting of the American Society of Gene & Cell Therapy (ASGCT) in May.

The presentation will feature interim safety and efficacy results from the POLARIS Phase 1/2 clinical trials of ETX101 in children with SCN1A+ Dravet syndrome. For families and clinicians battling this relentless condition, the event marks a moment of significant hope, potentially heralding a shift from lifelong symptom management to a single-dose, disease-modifying intervention.

A New Approach for a Devastating Disease

Dravet syndrome is a rare and severe developmental and epileptic encephalopathy that begins in the first year of life. It is characterized by frequent, prolonged, and treatment-resistant seizures. However, the impact of the disease extends far beyond seizures, causing profound cognitive dysfunction, developmental delays, motor impairments, and a significantly increased risk of sudden unexpected death in epilepsy (SUDEP).

In nearly 90% of cases, the disorder is caused by a spontaneous mutation in the SCN1A gene. This gene provides instructions for making the NaV1.1 sodium channel, which is critical for the proper function of GABAergic inhibitory neurons—the brain's 'braking system.' With only one functional copy of the gene, these neurons cannot fire properly, leading to the brain hyperexcitability that drives the disease's debilitating symptoms.

Current treatments, which include a cocktail of anti-seizure medications, specialized diets, and nerve stimulation, offer only partial relief from seizures and do little to address the underlying neurodevelopmental decline. This leaves a vast unmet need for therapies that can correct the fundamental genetic problem.

Beyond Seizure Control: The Promise of ETX101

Encoded Therapeutics' ETX101 is designed to do just that. Instead of replacing the faulty gene, it employs a sophisticated gene regulation approach. The therapy uses a well-studied adeno-associated virus (AAV9) vector to deliver a payload directly into the cerebrospinal fluid via a one-time intracerebroventricular injection. This payload contains an engineered regulatory element designed to selectively target GABAergic neurons and dial up the expression of the existing healthy copy of the SCN1A gene.

The goal is to restore NaV1.1 protein levels to near-normal, re-establishing the brain's inhibitory balance and addressing the root cause of the disease. The approach represents a new frontier in precision medicine, aiming to modulate the body's own genetic machinery with cellular specificity.

While the full data set will be revealed at ASGCT, previously disclosed interim results from the POLARIS program have already generated significant excitement. Data presented in late 2025 from 19 participants showed that ETX101 was well-tolerated and demonstrated dose-dependent efficacy. At the highest dose tested, patients experienced a median reduction in monthly seizure frequency of 87%.

More remarkably, the therapy appeared to impact the disease's neurodevelopmental course. Clinicians observed progressive and meaningful gains in cognitive and adaptive skills in treated children, particularly those who received the therapy before the age of two. This suggests ETX101 may have the potential to rescue or even prevent the developmental stagnation that is a hallmark of Dravet syndrome, a feat current treatments cannot achieve.

A High-Stakes Showcase at ASGCT

The selection of ETX101 for an oral presentation at the ASGCT Presidential Symposium is a significant external validation. This session is reserved for the highest-rated and most impactful scientific abstracts submitted to the conference, placing Encoded's work among the most promising advancements in the entire field of gene and cell therapy this year.

“We are incredibly proud to present our latest POLARIS data at this prestigious ASGCT platform, showcasing ETX101's potential to improve seizure control and fundamentally rescue learning and cognitive development in children living with Dravet syndrome,” said Sal Rico, M.D., Ph.D., Chief Medical Officer of Encoded, in the company's press release. “These findings underscore our vector engineering approach and its potential to deliver precision one‑time genetic medicines for neurological disorders.”

While Encoded is making strides, it is not alone in the race to develop a disease-modifying therapy for Dravet. Stoke Therapeutics is advancing an antisense oligonucleotide (ASO) therapy, Zorevunersen, which also aims to boost NaV1.1 protein levels. However, Stoke's approach requires repeat dosing, distinguishing it from Encoded's one-and-done gene therapy strategy, which could offer a significant long-term advantage if proven safe and durable.

A Platform for the Future of Neurological Medicine

Encoded's ambitions extend well beyond Dravet syndrome. The company will also present two scientific posters at ASGCT that highlight the versatility of its 'vector engineering' platform. One poster will detail preclinical data on NociPro, a novel regulatory element designed to target pain-sensing neurons for the treatment of chronic pain. Another will showcase an experimental approach for Angelman syndrome, a different severe neurogenetic disorder, which uses a vectorized microRNA to unsilence the UBE3A gene.

Together, these presentations paint a picture of a company building a powerful and adaptable technology engine capable of addressing a wide range of neurological conditions. This platform approach has already attracted high-profile validation, including a 2024 collaboration with Prevail Therapeutics, a subsidiary of Eli Lilly and Company, granting Lilly access to Encoded’s proprietary regulatory elements.

Supported by over $239 million in venture financing from top-tier investors like GV (formerly Google Ventures) and ARCH Venture Partners, Encoded is methodically advancing its pipeline. The upcoming ASGCT presentation will be a critical data point for the company, its investors, and most importantly, the patient communities who see these scientific advances as a beacon of hope for a different future.