Neurogene Inc. announced that the first patient in Cohort 2 received high-dose NGN-401 gene therapy in the Phase 1/2 trial for female pediatric patients with Rett syndrome, and high-dose NGN- 401 has been well-tolerated following dosing in May 2024. The Company also provided an update on interim safety data on the first three patients in the low-dose cohort during the IRSF ASCEND 2024 Rett Syndrome National Summit, which shows that NGN-401 has continued to have a favorable safety profile with no new treatment-related adverse events (AEs). During an oral and poster presentation, Bernhard Suter, M.D., Medical Director of the Blue Bird Circle Rett Center at Texas Children?s Hospital, Associate Professor of Pediatrics and Neurology at Baylor College of Medicine, and principal investigator in the NGN-401 clinical trial, will present an updated safety presentation on the first three low-dose patients.

These data show: NGN-401 continues to have a favorable safety profile; There have been no new treatment-related adverse events (AEs) since the last safety update during the American Society of Gene and Cell Therapy (ASGCT) Annual Meeting; all treatment-related AEs have been mild/Grade 1, and transient or resolving, and most AEs are known potential risks of AAV; No signs or symptoms indicative of MeCP2 overexpression toxicity have been reported, including in the patient with a mild genetic variant predicted to result in residual MeCP2 expression; No treatment-emergent or intracerebroventricular (ICV) procedure-related serious AEs.