A potential new gene therapy for the treatment of Duchenne muscular dystrophy (DMD), RGX-202, has received Fast Track designation from the US Food and Drug Administration (FDA).

This means that the drug candidate will have the opportunity to interact with the FDA more frequently and may qualify for priority review.

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In a press release by REGENXBIO, the developers of RGX-202, Debra Miller, founder and chief executive officer of CureDuchenne, a global charity supporting research and patient care in DMD, said, ”We are pleased that the FDA has granted Fast Track designation for RGX-202. Accelerating the development of medicines for Duchenne, especially potential one-time gene therapies like RGX-202, is critical for this community.”

RGX-202 is an adeno-associated virus (AAV)-based therapy that includes an optimized transgene for a novel microdystrophin. It is currently being investigated in a phase 1/2 clinical trial called AFFINITY DUCHENNE. 

The interventional, nonrandomized trial is currently recruiting patients with DMD, aged 4 to 11 years, at Arkansas Children’s Hospital and Ann & Robert H. Lurie Children’s Hospital of Chicago. It started on January 4, 2023 and is estimated to be completed in December 2025. Initial data from the trial are expected in the second half of 2023. 

DMD is a rare genetic disease caused by a mutation in the DMD gene, which encodes the dystrophin protein. This protein is essential for the health of muscle cells, and its absence leads to progressive muscle damage and atrophy.

There is currently no cure for DMD, but there are many experimental treatments in development.

Gene therapy in which a functional copy of the DMD gene is delivered to the body using an AAV vector is a promising approach. However, because the DMD gene is the largest gene in the human body, it cannot be delivered at its full length. 

RGX-202 contains a transgene for a novel microdystrophin that includes the functional elements of the C-terminal domain found in full-length dystrophin, which has been shown to improve muscle resistance to damage induced by contractions.


REGENXBIO receives FDA Fast Track designation for RGX-202, a novel gene therapy candidate for the treatment of Duchenne muscular dystrophy. News release. REGENXBIO Inc; April 11, 2023.