Neurogene (NGNE) said Monday it likely will not move forward with its NGN-101 CLN5 Batten disease gene therapy program after the US Food and Drug Administration denied a Regenerative Medicine Advance Therapy application for the program.

Neurogene shares were falling 35% in recent after-hours trading.

"Given the rarity of the disease, continued investment in the program was predicated on alignment on a streamlined registrational pathway with FDA," the company said, adding the regulator denied the RMAT application.

Neurogene said it's "evaluating options for the program."

Neurogene also said Monday it has seen "positive" interim results in the first four participants in the low-dose group of a phase 1/2 trial assessing NGN-401 gene therapy to treat female pediatric patients with Rett syndrome, a neurodevelopmental disease.

The company said it expects to provide an update of registrational trial design in H1 2025 and will release more interim phase 1/2 results in H2 2025.