Neurogene Advances AAV9 Gene Therapy NGN-401 for Rett Syndrome With Registrational Trial Progress

NEW YORK, Jan. 12, 2026 (BUSINESS WIRE) — Neurogene Inc. (Nasdaq: NGNE), a clinical-stage biotechnology company focused on genetic medicines for rare neurological disorders, reported significant progress in the development of NGN-401, an AAV9-based gene therapy for the treatment of Rett syndrome, alongside multiple anticipated milestones expected in 2026.

During the fourth quarter of 2025, Neurogene dosed multiple participants in the Embolden™ registrational trial evaluating NGN-401, an adeno-associated virus (AAV) gene therapy, marking a key step toward completion of enrollment. The company expects to complete dosing in the registrational trial in the second quarter of 2026 across 13 active U.S. clinical sites.

NGN-401 is an investigational AAV9 gene therapy designed as a one-time treatment for Rett syndrome. The therapy uses an AAV9 vector to deliver the full-length human MECP2 gene, regulated by Neurogene’s proprietary EXACT™ transgene control technology. This AAV-based gene therapy approach is intended to achieve therapeutic MECP2 expression while avoiding overexpression-related toxicity, a critical challenge in Rett syndrome treatment.

Neurogene continues to monitor participants enrolled in its ongoing Phase 1/2 trial of AAV gene therapy NGN-401, with plans to present updated interim safety and efficacy data in mid-2026. The planned data presentation will include pediatric patients (ages 4–10) and adolescent/adult patients (ages ≥11), with at least 12 months of follow-up for all participants. Previously reported interim results demonstrated durable, multidomain clinical improvements across a broad spectrum of disease severity following AAV9 gene therapy administration.

In parallel with clinical advancement, Neurogene has initiated early commercial-readiness activities for its AAV gene therapy program, including payer engagement and internal chemistry, manufacturing, and controls (CMC) efforts to support commercial-scale AAV manufacturing. The company expects its current cash runway to extend into the first quarter of 2028, supporting continued advancement toward a planned Biologics License Application (BLA) submission.

NGN-401 has received multiple regulatory designations recognizing its potential as a differentiated AAV gene therapy, including FDA START Pilot Program selection, Regenerative Medicine Advanced Therapy (RMAT) designation, Orphan Drug designation, Fast Track designation, and Rare Pediatric Disease designation. Internationally, the AAV gene therapy has also been granted PRIME, orphan, and Advanced Therapy Medicinal Product (ATMP) designations by the European Medicines Agency, as well as ILAP designation from the UK MHRA.