Duchenne muscular dystrophy (DMD) is an inherited disease that weakens a child’s muscles and eventually spreads throughout the child’s body. DMD is caused by mutations in the gene that helps create the dystrophin protein which in turn protects muscle fibers and keep them stable. DMD primarily affects two-to five-year-old boys. The dystrophin gene is on the X chromosome that contain genes. Boys only have one X chromosome whereas girls have two X chromosome genes.
Another symptom involves the heart muscle that may become enlarged, although some people have lived to age 40 or 50 with good treatment. Yet, there is no cure. The mutations (changes) rob the child’s body of dystrophin causing the muscle cells to eventually die. If it is still possible for a gene to manufacture some dystrophin, the child will exhibit milder symptoms called Becker muscular dystrophy.
Currently there is only one drug, Elevidys, approved as gene therapy for Duchenne muscular dystrophy. The drug’s approval has been limited to patients who are four or five years of age.
The AFFINITY DUCHENNE® Trial Design
The Phase 1/2 AFFINITY DUCHENNE trial evaluates a one-time intravenous dose of RGX-202 for safety, tolerability, and efficacy. The four ambulatory Duchenne pediatric patients participating in the trial are 4 through 11 years of age. Upon completion of a satisfactory independent safety review additional patients may be enrolled during the expansion phase.
Kenneth Mills, CEO of Regenxbio reported that one of the participants, a 12-year-old boy, exhibited increased microdystrophin expression. Caregivers for the other four participants who were also treated with RGX-202 reported improvements as well. These boys had completed their three-month assessments and displayed positive increases in RGX-202.
About RGX-202
The biology of RGX-202 is similar to naturally occurring dystrophin which protects the muscles from deteriorating. RGX-202 delivers a transgene, created in the lab, for a newly developed microdystrophin that involves elements of the C-Terminal (CT). CT has been found in some studies to transform key proteins that led to improvements in muscle resistance in dystrophic mice. Regenxbio plans to start a decisive trial towards the end of the year.
