Regenxbio Inc., a Maryland-based gene therapy company, announced new interim data from the Phase I/II AFFINITY DUCHENNE trial of RGX-202 in patients with Duchenne muscular dystrophy. The data, presented at the Muscular Dystrophy Association Clinical and Scientific Conference, showed that participants receiving the pivotal dose exceeded external controls across functional measures at one year, according to the company.
Trial specifics
The AFFINITY DUCHENNE trial is a Phase I/II study evaluating RGX-202 as a gene therapy for Duchenne muscular dystrophy. According to the interim data, participants receiving the pivotal dose demonstrated functional outcomes exceeding external controls at one year, including among participants aged eight and older. The company also reported cardiac MRI data for pivotal dose patients alongside safety, biomarker, and additional functional data at the conference. The trial appears to rely on external control comparisons rather than a randomized placebo-controlled design.
The company described RGX-202 as a gene therapy candidate for Duchenne muscular dystrophy, and the presentation of data at the MDA conference suggests the program remains in active clinical development. The company did not state whether a pivotal trial or registrational study is planned, nor did it indicate whether the current Phase I/II data would support a regulatory submission. No existing approvals for RGX-202 were referenced.
Research context
RGX-202 is a gene therapy designed to deliver a functional gene construct intended to produce a form of dystrophin, the protein that is absent or deficient in patients with Duchenne muscular dystrophy. Duchenne is caused by mutations in the DMD gene, which encodes dystrophin, a structural protein that stabilizes muscle cell membranes during contraction. Without functional dystrophin, muscle fibers undergo progressive damage, leading to loss of ambulation and cardiorespiratory decline. Gene therapies for Duchenne typically deliver a truncated version of the dystrophin gene, known as micro-dystrophin, using adeno-associated virus vectors. The company did not specify the vector serotype or transgene design for RGX-202 in the available materials.
The treatment landscape for Duchenne muscular dystrophy includes corticosteroids as long-standing standard of care, along with several targeted therapies. Key competitors include:
- Sarepta Therapeutics’ delandistrogene moxeparvovec (Elevidys), an AAV-based micro-dystrophin gene therapy that received accelerated approval from the US FDA in 2023 for ambulatory Duchenne patients aged four and five, later expanded to include broader age groups, but as of November 14, 2025, revised to limit Elevidys to ambulatory Duchenne patients aged 4 years and older with the non-ambulatory indication removed.
- Sarepta Therapeutics’ eteplirsen (Exondys 51), an exon-skipping antisense oligonucleotide approved by the US FDA in 2016 for patients with a confirmed mutation amenable to exon 51 skipping
- NS Pharma’s viltolarsen (Viltepso), an exon 53 skipping therapy approved by the US FDA in 2020
The interim data from the AFFINITY DUCHENNE trial position RGX-202 within a competitive field where Sarepta’s Elevidys holds the only approved gene therapy. Regenexbio will be hoping RGX-202 can differentiate on durability, cardiac outcomes, or efficacy in older patients.