Regnexbio’s bid to develop a gene therapy for Duchenne muscular dystrophy (DMD) has received an important regulatory lift.

The US Food and Drug Administration (FDA) granted fast track designation for Regenxbio’s DMD candidate RGX-202, hastening the gene therapy’s development timeline. RGX-202 is currently recruiting for the Phase I/II AFFINITY DUCHENNE study (NCT05693142), which will have initial data available in the second half of 2023.

The regulatory designation gives Regnexbio a much-needed push, as RGX-202 lags behind key competitors in the race to bring a DMD gene therapy to market.

Sarepta’s gene therapy SRP-9001 is in a Phase III trial (NCT05096221) and could receive an FDA accelerated approval by May 29. Meanwhile, Pfizer’s gene therapy PF-06939926 is recruiting patients in a Phase III trial (NCT04281485) after rebounding from earlier safety concerns.

The crowded field of DMD drug development also features monoclonal antibodies, synthetic steroids, and even an allogenic stem cell therapy.

DMD is characterized by alterations in the protein dystrophin, causing progressive muscle loss primarily in young boys. RGX-202 is a one-time gene therapy using an adeno-associated vector (AAV) to deliver microdystrophin, a shortened form of the dystrophin protein intended to restore partial muscle function.

Building Regenxbio’s pipeline

RGX-202 forms part of RegenxBio’s self-described “5×25 strategy” to have five AAV therapies in the market or in late-stage development by 2025. Regenxbio also has gene therapies in development for Hunter syndrome, age related macular degeneration, and diabetic retinopathy, among others.

The Phase I/II AFFINITY DUCCHENE study has a target enrollment of 18 boys between the ages of 4 and 11. The primary endpoint focuses on safety, while secondary endpoints include microdystrophin expression and the North Star Ambulatory Assessment (NSAA) which measures DMD function.

Cell & Gene Therapy coverage on Clinical Trials Arena is supported by Cytiva.

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