Regenxbio plans to provide updates on its RGX-181 and RGX-381 gene therapy candidates for neuronal ceroid-lipofuscinosis type 2 (CLN2) disease in late infants, one of the most common forms of the disease. of Batten, in the second half of this year.
The company is currently reviewing U.S. Food and Drug Administration (FDA) requests for information regarding a clinical suspension the agency placed on a proposed RGX-181 trial, after the company submitted a request for a new investigational drug (IND).
In an open letter to the Batten’s disease community, Regenxbio said the FDA had requested more information regarding “the selection of the starting dose and certain procedures for administering the study drug.”
The delay in responding to the FDA’s request also pushed updates on the RGX-381 program into the second half of the year. Regenxbio intended to submit an IND application for RGX-381 this year to the FDA or foreign pharmaceutical regulators.
RGX-181 is a unique experimental gene therapy designed to provide a functional copy of the TPP1 gene to cells of the central nervous system (CNS, brain and spinal cord).
mutations in TPP1 cause CLN2. The enzyme produced by this gene is essential for breaking down fat and protein molecules called lipofuscins, which then build up in toxic amounts, eventually killing the cells they’re in. Nerve cells are particularly susceptible to damage from lipofuscins, resulting in the neurological symptoms seen in CLN2.
Preclinical data from studies involving animal models of CLN2 showed that a single injection of RGX-181 significantly improved neurological symptoms and animal survival times by increasing the amount of TPP1 enzyme in the CNS.
The FDA has granted the investigational therapy the Rare Pediatric Disease and Orphan Disease designations, both intended to make it easier to bring a potential drug to market.
RGX-381 is intended to provide the TPP1 gene directly to the retina – the layer of the eye containing photosensitive cells – to correct symptoms of CLN2 in the eyes (ocular manifestations). Ocular manifestations generally appear around the age of 4 years. They involve rapid vision loss, progressing to blindness over several years. There is currently no treatment for CLN2 related vision loss.
Both therapies use an adeno-associated virus to deliver their copies of TPP1. These non-replicating viruses are a common gene therapy tool, used because they cannot cause disease and rarely trigger immune responses.