REGENXBIO Reports Positive Phase 3 AFFINITY DUCHENNE Results for RGX-202 Gene Therapy

REGENXBIO announced positive topline and interim functional data from the pivotal Phase 3 portion of the AFFINITY DUCHENNE trial evaluating investigational gene therapy RGX-202 in patients with Duchenne muscular dystrophy (DMD). According to the company, the trial met its primary endpoint with high statistical significance, with 93% of participants achieving microdystrophin expression above 10% at Week 12 (p<0.0001).¹

The Phase 1/2/3 AFFINITY DUCHENNE study evaluated RGX-202 in ambulatory boys aged 1 year and older. Interim data also demonstrated a statistically significant correlation between RGX-202 microdystrophin expression levels and functional improvement, including North Star Ambulatory Assessment scores in a subset of patients evaluated at 12 months post-treatment.¹

REGENXBIO reported that average microdystrophin expression reached 71.1% across all participants and 41.6% in boys older than 8 years of age. Additionally, 80% of participants achieved microdystrophin expression levels above 40%.¹

Safety and Functional Findings

According to the company, RGX-202 was generally well tolerated and demonstrated a favorable interim safety profile, with no new safety concerns identified.¹ Interim functional analyses included nine participants aged older than 4 years who were evaluated one year after treatment.¹

“Duchenne muscular dystrophy is a rare, progressive neuromuscular disease characterized by worsening muscle weakness and loss of function, and there continues to be a critical unmet need for therapies that can reliably alter the course of the disease,” Dr. Aravindhan Veerapandiyan, principal investigator for the AFFINITY DUCHENNE trial at Arkansas Children’s Hospital, said in a press release. “It’s encouraging to see robust microdystrophin expression, correlation with functional outcomes, and a manageable safety profile.”¹

DMD is a rare inherited neuromuscular disorder caused by mutations in the dystrophin gene and is characterized by progressive muscle degeneration and weakness.² Current gene therapy approaches for DMD often focus on delivering shortened microdystrophin constructs intended to restore muscle function.³

Regulatory Plans and Manufacturing Strategy

REGENXBIO stated that the topline findings support plans for a potential accelerated approval filing in 2027. The company also reported that more than 20 participants have been enrolled in the confirmatory portion of the study, with dosing expected to be completed in all 60 patients across the pivotal and confirmatory trials by mid-2026.¹

According to REGENXBIO, RGX-202 includes a differentiated therapeutic design featuring a novel microdystrophin construct containing the C-terminal domain, along with a proactive immune suppression regimen and suspension-based manufacturing process intended to improve product purity and durability.¹

“These topline results are exciting for the Duchenne community,” said Pat Furlong, founding president of Parent Project Muscular Dystrophy. “For decades, our community has pushed for therapies that can change the trajectory of this disease, and today’s news gives us renewed optimism.”¹

The company said additional data from the AFFINITY DUCHENNE trial are expected to be presented at future scientific meetings and included in planned regulatory submissions.

References

• REGENXBIO Announces Positive Topline Results from Pivotal Phase III AFFINITY DUCHENNE® Study of RGX-202. (2026 May 14). PR Newswire. https://www.prnewswire.com/news-releases/regenxbio-announces-positive-topline-results-from-pivotal-phase-iii-affinity-duchenne-study-of-rgx-202-302771834.html?utm_source=chatgpt.com

1. National Institute of Neurological Disorders and Stroke: Duchenne muscular dystrophy information page
2. Muscular Dystrophy Association: Gene therapy approaches for Duchenne muscular dystrophy