Encoded Therapeutics Raises $275M to Advance AAV Gene Therapy ETX101 for Dravet Syndrome

Encoded Therapeutics closed a $275 million Series F financing, co-led by GV and an undisclosed healthcare investor, with participation from ARCH Venture Partners, Braidwell, Farallon Capital Management, Illumina Ventures, Invus, Janus Henderson Investors, Matrix Capital Management, Nolan Capital, RTW Investments, SoftBank Vision Fund 2, and Venrock.¹ Proceeds will fund the pivotal study of ETX101 in infants and young children with SCN1A-positive Dravet syndrome, an expansion study in children and adolescents up to age 18, and commercial-scale buildout of Encoded's internal GMP manufacturing capabilities.¹ The financing also positions ETX301, a separate pipeline candidate, toward a 2027 Investigational New Drug submission for post-amputation neuroma pain.¹

Kartik Ramamoorthi, Ph.D., chief executive officer of Encoded, said, "The interim Phase 1/2 POLARIS data we recently shared at the European Epilepsy Congress demonstrate substantial and sustained seizure frequency reductions alongside encouraging developmental gains. This progress strengthens our conviction in ETX101 and the potential of our approach to meaningfully alter the course of Dravet syndrome. With pivotal development underway, this financing gives us the resources to advance ETX101 toward registration while continuing to build the capabilities and pipeline that will define Encoded's next stage."¹ Brendan Bulik-Sullivan, Ph.D., general partner at GV, said, "The emerging clinical profile of ETX101 is increasingly compelling with durable seizure control and promising neurodevelopmental signals, reinforcing its potential as a transformative therapy. We are pleased to co-lead this financing and support Encoded as it advances ETX101 through pivotal development."¹

What does ETX101 do, and what data supports it?

ETX101 is designed as a one-time, disease-modifying treatment for Dravet syndrome caused by SCN1A mutations, using an AAV9 vector to deliver a gene regulation therapy that upregulates the patient's own remaining functional copy of SCN1A within GABAergic inhibitory interneurons, rather than delivering the SCN1A coding sequence itself.² This approach reflects a specific engineering constraint: SCN1A is a large gene, which has historically made it difficult to package within the size limits of standard AAV vectors, and simply over-expressing SCN1A can itself be deleterious, ruling out straightforward gene replacement.³ Encoded's preclinical work, published in Human Gene Therapy, showed that a single dose of the AAV9 gene regulation construct rescued mortality and seizure phenotypes in a Dravet syndrome mouse model and was well tolerated in nonhuman primates.² Interim Phase 1/2 POLARIS data presented at the European Epilepsy Congress showed substantial, sustained reductions in seizure frequency alongside developmental and cognitive gains across 21 treated participants in the ENDEAVOR, WAYFINDER, and EXPEDITION studies that comprise the program.⁴

How does this fit in with other approaches to treating Dravet syndrome?

Dravet syndrome is a severe, infantile-onset genetic epilepsy caused by SCN1A mutations in roughly 80% of cases, disrupting the balance of excitatory and inhibitory signaling in the brain and producing frequent, often treatment-resistant seizures alongside developmental and cognitive impairment.⁵ Encoded is not the only company pursuing a genetic medicine approach to the disease. BioPharm International spoke with Daniel Fischer, co-founder and CEO of Tevard Biosciences, at the 2025 BIO International Convention, where he discussed his company's alternative approach to the same SCN1A size constraint: "By using tRNAs, we can actually target diseases which are not amenable to traditional methods of gene therapy," Fischer said.³ Rather than delivering or regulating the SCN1A gene directly, Tevard's platform uses suppressor tRNAs to correct premature stop-codon mutations, which account for roughly 25% of Dravet cases.³ Encoded's gene regulation strategy addresses the same underlying packaging-capacity problem differently — rather than delivering a replacement copy of the gene, it upregulates expression from the patient's existing functional allele.

David Schenkein, M.D., general partner and co-lead of life sciences at GV, said, "Progress with ETX101 provides important validation of Encoded's differentiated approach to genetic medicine and the broader potential of its platform. Encoded is well positioned to build a significant portfolio of medicines across neurological diseases, where more precise and durable biological intervention could meaningfully improve outcomes."¹

What happens next?

Encoded expects to advance ETX101 through pivotal development toward registration, alongside the previously announced expansion study for older children and adolescents.¹ The company will also use the financing to scale up internal GMP manufacturing and continue building out its broader precision genetic medicines pipeline in neurology, including advancing ETX301 toward a planned 2027 IND submission.¹

References

1. Encoded Therapeutics, Inc. Encoded Therapeutics Raises $275 Million in Series F Financing to Advance ETX101 Through Pivotal Development and Accelerate its Precision Genetic Medicines Neurology Pipeline. Press release. Published September 9, 2026. Accessed September 10, 2026.
2. Tanenhaus A, Stowe T, Young A, et al. Cell-Selective Adeno-Associated Virus-Mediated SCN1A Gene Regulation Therapy Rescues Mortality and Seizure Phenotypes in a Dravet Syndrome Mouse Model and Is Well Tolerated in Nonhuman Primates. Hum Gene Ther. 2022;33(13-14):711-727. doi:10.1089/hum.2022.037.
3. Cole C. Patient-Driven Innovation and an Investigational tRNA-based Gene Therapy. BioPharm International. Published June 17, 2025. Accessed September 10, 2026.
4. Meglio M. ETX101 Gene Therapy Shows Early Developmental, Seizure Benefits in Dravet Syndrome. CGTLive. Published May 13, 2026. Accessed September 10, 2026.
5. Zhang G, Huang S, Wei M, et al. Dravet Syndrome: Novel Insights Into SCN1A-Mediated Epileptic Neurodevelopmental Disorders Within the Molecular Diagnostic-Therapeutic Framework. Front Neurosci. 2025;19:1634718. doi:10.3389/fnins.2025.1634718.