According to a November 23 article from Muscular Dystrophy News, the FDA recently granted Orphan Drug designation to clinical-stage biotechnology company Regenxbio’s experimental gene therapy candidate, RGX-202. The gene therapy, designed for Duchenne muscular dystrophy (DMD), is still currently in the preclinical development phase.
So what exactly is RGX-202? According to Regenxbio, RGX-202 is:
an investigational gene therapy utilizing a novel microdystrophin construct [that] aims to address the underlying cause of DMD, independent of genetic mutation, by potentially enabling production of microdystrophin in muscle cells to protect them from damage and ultimately preserve muscle function.
As current therapeutic options may only help those with certain gene mutations, RGX-202 could change the treatment arena for people with DMD. The therapy, which uses a proprietary NAV AAV8 vector, is designed for a singular administration. Once administered, RGX-202 could code for shortened, but still functional, dystrophin while also enhancing gene expression.
Recently, the drug was given Orphan Drug designation from the FDA. This status is granted to products intended to treat, cure, or prevent rare diseases within the United States; these are defined as conditions affecting under 200,000 Americans. Because of this status, Regenxbio also receives a variety of incentives, such as fee waivers, tax credits, increased regulatory assistance, and 7 years of market exclusivity upon approval.
Duchenne Muscular Dystrophy (DMD)
Duchenne muscular dystrophy (DMD) is one of the nine muscular dystrophy subsets. This rare condition results from a genetic mutation, inherited in an X-linked recessive pattern, which prevents the body from making dystrophin. Normally, this protein plays a role in muscle strength and protection. Because their bodies do not make dystrophin in the muscles, people with DMD experience progressive muscle weakness and degeneration. Symptoms usually manifest prior to 6 years old, and may often appear between ages 2-3. These include, but are not limited to:
- Progressive muscle weakness that begins in the lower extremities
- Learning disabilities
- Delayed speech
- A “waddling” gait
- Difficulty walking, running, jumping, or changing positions
- Frequent tripping and/or falling
- Lumbar lordosis
- Enlarged calves
- Respiratory failure
- Heart disease