As a result, the trial will include additional patients in cohort 1 and a dose-escalation cohort.

NGN-401 is 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 technology.

“We are excited to share that we have met our first 2024 program milestones, including dosing the third patient in the NGN-401 phase 1/2 trial for Rett syndrome and expansion of the trial to include more patients in the current dosing cohort and the addition of a high dose cohort,” said Rachel McMinn, CEO and founder of Neurogene.

“Our clinical development strategy has been to build flexibility and optionality early in the program with two concurrent dose cohorts designed to generate a more complete data package, which we expect will inform future registration discussions with global health authorities.

“We expect that expansion of the clinical trial and the removal of staggered dosing in cohort 1 will enable us to treat more patients in a shorter period of time. Based on this update, we expect to complete enrollment of cohort 1 in the second half of 2024.”

Rett syndrome is a rare genetic neurological disorder that occurs almost exclusively in girls and causes severe impairments, affecting speech and movement. 

So far, research has found NGN-401 to be generally well-tolerated with no adverse events or signs of overexpression-related toxicity observed in any patient.

Neurogene’s EXACT gene regulation platform technology is a self-contained transgene regulation platform that can be tuned to deliver a desired level of transgene expression within a narrow and therapeutically relevant range, with the goal of avoiding transgene-related toxicities associated with conventional gene therapy.

The company remains on track to report interim clinical data from cohort 1 in Q4 of 2024 and additional data, including from cohort 2, in the second half of 2025.