Exceeded target by dosing a total of 25 participants with NGN-401 in registrational trial due to strong demand from Rett syndrome community

NGN-401 has been generally well-tolerated, with no cases of HLH at the 1E15 vg dose; additional interim Phase 1/2 data expected mid-2026

Topline data from Embolden anticipated in 2H 2027

Neurogene Inc. (NASDAQ:NGNE), a clinical-stage company founded to bring life-changing genetic medicines to patients and families affected by rare neurological diseases, today announced the successful completion of dosing in the Embolden™ registrational trial of NGN-401, an investigational gene therapy designed to be a potential best-in-class, one-time treatment for Rett syndrome. While the initial enrollment target was 20 participants, the statistical analysis plan pre-specified an intent-to-treat (ITT) population of up to 24 participants, providing flexibility to support robust trial execution. Due to strong demand from the Rett syndrome community and to ensure timely completion of dosing, the Company elected to overenroll the trial and dose all eligible participants already in screening for a total of 25.