Neurogene Inc. announced a business update and provided its outlook for 2024. Key milestones for the Company?s clinical-stage gene therapy product candidates remain on track for 2024, while the Company continues to advance its discovery-stage transgene regulation portfolio. Anticipated 2024 Key Milestones: Rett Syndrome ?

NGN-401- Expand ongoing Phase 1/2 clinical trial for NGN-401 for Rett syndrome in 1H:24 to enroll a larger cohort of patients; Report interim Phase 1/2 clinical data for NGN-401 for Rett syndrome in 4Q:24. CLN5 Batten Disease ? NGN-101: Report interim Phase 1/2 clinical data for NGN-101 in 2H:24, Engage in discussions with U.S. Food and Drug Administration (FDA) regarding a streamlined registrational pathway for NGN-101 in 2H:24.

Neurogene announced that the Data Safety Monitoring Board (?DSMB?) for the ongoing Phase 1/2 clinical trial of NGN-401 in female pediatric patients with Rett syndrome has recommended that the trial continue, which enables dosing of the third patient. This recommendation was based on safety data collected to date, following dosing of the first patient in the third quarter of 2023 and the second patient in the fourth quarter of 2023. Neurogene also announced that the United Kingdom (UK) Medicines and Healthcare products Regulatory Agency (MHRA) has approved the Company?s clinical trial application (CTA) for NGN-401, marking the second regulatory clearance for NGN-401 in pediatric patients with Rett syndrome.

This clearance enables Neurogene to expand enrollment in the Phase 1/2 trial beyond the United States to include patients with Rett syndrome in the UK, and is part of Neurogene?s global development and trial expansion strategy. The ongoing NGN-401 Phase 1/2 clinical trial specifies a cohort of five patients, each receiving a total dose of 1×1015 total vector genomes delivered via intracerebral ventricular administration, which Neurogene believes may show promising efficacy results based on the nonclinical data package generated for NGN-401. In the first half of 2024, Neurogene plans to expand the trial to include (1) more patients in Cohort 1 of the trial for the low dose, and (2) a higher dose cohort to maximize the efficacy potential while still maintaining a favorable safety profile, pending regulatory clearances.

Importantly, based on a comprehensive nonclinical dataset, the EXACT transgene regulation technology embedded in NGN-401 mechanistically constrains MECP2 transgene expression levels, allowing for the potential to dose escalate and enhance biodistribution to the brain, without the commensurate increase in MECP2 transgene expression observed with conventional gene therapy. Neurogene expects to report interim clinical data from Cohort 1 in the fourth quarter of 2024, which is expected to include extensive follow up data on the first number of patients dosed. Neurogene has completed enrollment of Cohorts 1 and 2 in the ongoing Phase 1/2 clinical trial for CLN5 Batten disease, and interim clinical data are expected in the second half of 2024.

Neurogene is currently enrolling a final higher dose cohort. In the fourth quarter of 2023, Neurogene completed a positive meeting with the FDA regarding the future potency assay. The FDA accepted Neurogene?s proposed potency assay strategy and provided alignment with the testing approach, which will allow release of all future NGN-101 batches.

To enable a go/no-go decision to advance the program into a registration study, Neurogene is collecting and analyzing natural history data for CLN5 Batten disease and planning to request a clinical/regulatory strategy meeting with the FDA in the second half of 2024. The focus of this meeting will be to align with the FDA on the expected clinical requirements to support a streamlined registration pathway, which will be necessary to move this program forward into a pivotal clinical trial.