> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Neurogene Gene Therapy Patient Dies After Dosing
- URL: https://www.fdaweb.com/neurogene-gene-therapy-patient-dies-after-dosing/
- Published: 2024-11-22T12:00:00.000Z
- Updated: 2026-09-14T14:47:54.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5158243

Neurogene is [reporting](https://www.sec.gov/ix?doc=/Archives/edgar/data/1404644/000140464424000109/ngne-20241120.htm&ref=fdaweb.com) that a patient dosed in an ongoing Phase 1/2 gene therapy clinical trial for Rett syndrome has died following complications from a rare and life-threatening hyperinflammatory syndrome associated with systemic exposure to high doses of adeno-associated virus (AAV), the company says.

Neurogene says FDA has allowed it to proceed with the trial using a lower dose (1E15 vg) for both the pediatric and adolescent/adult cohorts. “Neurogene will also incorporate the 1E15 vg dose in its future registrational trial design planning,” it says.

NGN-401 is described as an investigational AAV9 gene therapy being developed as a one-time treatment for Rett syndrome. “It is the first clinical candidate to deliver the full-length human MECP2 gene under the control of Neurogene’s EXACT transgene regulation technology,” the company says. EXACT technology is designed to address a treatment approach that enables targeted levels of MECP2 transgene expression without causing toxic effects from overexpression that is often associated with conventional gene therapies, it says.