Neoleukin Therapeutics: Neurogene Faces Challenges in Rett Syndrome Gene Therapy Trial

Neurogene Inc. Navigates Challenges in Rett Syndrome Gene Therapy Trial

Neurogene Inc., a clinical-stage biotechnology company, focuses on developing genetic therapies for rare neurological diseases. Recently, it provides an update on its Phase 1/2 open-label clinical trial of its gene therapy candidate, NGN-401, aimed at treating Rett syndrome. This update comes on the heels of a serious adverse event (SAE) involving a participant who received a high dose of NGN-401. On November 11, 2024, Neurogene reports that the participant is in critical condition due to a systemic hyperinflammatory syndrome, a severe immune response associated with high doses of adeno-associated virus (AAV). In light of this, Rachel McMinn, Ph.D., CEO of Neurogene, highlights the company's commitment to participant safety and expresses condolences to the affected family.

In response to the SAE, Neurogene engages with the U.S. Food and Drug Administration (FDA) to secure permission to continue the trial with a lower dose of 1E15 vg, while pausing enrollment for the high-dose cohort. The company notes that, to date, there have been no other treatment-related SAEs reported among participants receiving the lower dose, nor in the first two participants of the high-dose cohort. Adverse events reported in the low-dose group are mild and manageable, with no signs of MeCP2 overexpression toxicity or complications related to the intracerebroventricular procedure. Despite the need to revise its protocol following the discontinuation of the high-dose cohort, Neurogene remains focused on transparency and the welfare of its participants.

The interim data from the low-dose cohort shows promising results, with participants experiencing significant improvements in various areas related to Rett syndrome. According to Dr. McMinn, participants receiving the 1E15 vg dose have shown a 28 to 52 percent improvement on the Rett Syndrome Behavioral Questionnaire, with all rated as "much improved" on the Clinical Global Impression-Improvement scale. Given these encouraging results, Neurogene plans to update its trial protocol and will resume dosing once revisions are finalized. The company anticipates providing further updates on the trial design in the first half of 2025, reinforcing its commitment to advancing gene therapies for rare neurological conditions.

In addition to the clinical trial update, Neurogene reports its financial results for the third quarter of 2024, underscoring its focus on research and development. The emphasis on safety and efficacy in the ongoing trials sets a precedent in the biotechnology sector, particularly in developing treatments for rare diseases. As Neurogene navigates these challenges, it maintains its vision of delivering innovative therapies that can significantly alter the trajectory of conditions like Rett syndrome, which is characterized by developmental regression and loss of acquired abilities.