May 06, 2026 —
Encoded Therapeutics announced several key clinical and pipeline milestones, led by the dosing of the first patient in ENDEAVOR Part 2, the pivotal study of ETX101 for SCN1A-positive Dravet syndrome. The company also began dosing in ENDEAVOR Part 1B, an expansion study evaluating ETX101 in participants aged 4 to 18 years, broadening the program across the pediatric and adolescent Dravet population.
ETX101 is an investigational AAV9-based, cell-selective gene regulation therapy designed to increase SCN1A expression and restore sodium channel function in inhibitory interneurons. Dravet syndrome is a severe developmental and epileptic encephalopathy most commonly caused by SCN1A loss-of-function variants, leading to seizures, developmental impairment, behavioral symptoms, motor dysfunction, and high disease burden. By addressing the underlying genetic mechanism, ETX101 is being developed as a potential disease-modifying therapy rather than a symptomatic seizure-control approach alone.
The pivotal ENDEAVOR Part 2 study is evaluating seizure and neurodevelopmental outcomes in 30 infants and young children aged 6 months to 4 years. Enrollment is expected to complete by the end of 2026, with initial data anticipated by the end of 2027. The study is being conducted across multiple centers in the United States, United Kingdom, and Australia. In parallel, ENDEAVOR Part 1B will assess safety and preliminary efficacy in older children and adolescents aged 4 to 18 years, with initial data expected in the fourth quarter of 2026.
Encoded also announced that ETX101 has been selected for the FDA’s Chemistry, Manufacturing, and Controls Development and Readiness Pilot Program, or CDRP Program. The program is designed to help CMC development keep pace with accelerated clinical development timelines, particularly for therapies addressing serious unmet medical needs. For a complex AAV-based therapy such as ETX101, early CMC alignment may be critical to supporting late-stage development and potential regulatory review.
Beyond Dravet syndrome, Encoded nominated ETX301 as a development candidate for post-amputation neuroma pain, with an IND submission planned for 2027. ETX301 is an investigational AAV9-based vectorized microRNA therapy designed to selectively and durably knock down SCN9A, which encodes NaV1.7, a key mediator of pain signaling. The therapy is intended to target dorsal root ganglia nociceptive neurons and is designed for single intrathecal administration.
Preclinical data supporting ETX301 include durable NaV1.7 knockdown in non-human primates and sustained analgesic effects in rodent models of neuropathic pain. The initial target indication, lower limb post-amputation neuroma pain, represents a localized and well-defined neuropathic pain condition with substantial impact on function and quality of life.
Together, these updates highlight Encoded’s broader strategy of using AAV9-based precision genetic medicines to address severe neurological disorders through gene regulation, cell-selective expression, and durable modulation of disease-relevant pathways. With ETX101 moving into pivotal development and ETX301 advancing toward IND-enabling progress, Encoded is expanding its platform from pediatric epilepsy into chronic neuropathic pain.
