Neurogene's NGN-401 gene therapy for Rett syndrome has been granted Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA). The designation is based on the FDA's review of interim efficacy and safety data from the Phase 1/2 trial, with a data cutoff date of October 30, 2025. The interim data demonstrated clinically meaningful, durable, and multidomain functional improvements, including continued skill acquisition over time, for patients with Rett syndrome. NGN-401 is designed as a one-time treatment, delivering the full-length human MECP2 gene using Neurogene's proprietary EXACT transgene regulation technology. The therapy is administered intracerebroventricularly to achieve broad targeting directly to the brain and nervous system. The Embolden registrational clinical trial for NGN-401 is currently underway, with completion of dosing expected in the second quarter of 2026. Neurogene plans to present additional interim Phase 1/2 clinical data in mid-2026.