Present interim data for a phase I/II/III microdystrophin gene therapy clinical trial of RGX-202 in Duchenne muscular dystrophy.

Duchenne is a severe, progressive, degenerative muscle disease caused by mutations in the DMD gene which encodes for dystrophin, without which muscles degenerate and become weak, eventually leading to loss of movement and independence, required support for breathing, cardiomyopathy, and premature death.

RGX-202 is an investigational, one-time AAV gene therapy designed to deliver an optimized microdystrophin gene.  RGX-202 is the only gene therapy that encodes for a novel microdystrophin protein that includes the C-Terminal (CT) domain found in naturally occurring dystrophin.  In preclinical studies, the CT domain has been shown to protect muscles from contraction-induced stress and to improve muscle repair.

AFFINITY DUCHENNE®, a phase I/II/III multi-center, open-label trial of a one-time intravenous administration of RGX-202 at two dose-levels (DL1, 1x10¹⁴ or DL2, 2x10¹⁴ genome copies/kg body weight) is enrolling ambulatory boys aged one and above with Duchenne to evaluate safety, tolerability, and clinical efficacy. 

As of November 8, 2024, RGX-202 has been well tolerated in the Phase I/II portion (n=11) with no serious adverse events in boys aged 1-11 years old.  Participants demonstrated robust RGX-202 microdystrophin expression three months following RGX-202 administration at DL1 (10.4 – 83.4%; n = 3) and DL2 (20.8-77.2%; n = 6).  Functionally, RGX-202 participants demonstrated mean improved function on the North Star Ambulatory Assessment (NSAA) and time function tests at DL1 (12 months follow-up; n = 3) and DL2 (9 months follow-up; n = 2).  These participants also exceeded available external natural history controls matched for age and baseline function.

In the Phase I/II patients, RGX-202 has been well tolerated and demonstrated both robust RGX-202 microdystrophin expression and functional improvements.