REGENXBIO completed dosing in the confirmatory study of RGX-202 for Duchenne muscular dystrophy, supporting a planned FDA BLA submission in Q3 2026 and potential approval in 2027
Written By: Fariha Sameen, PharmD
Reviewed By: Pharmacally Editorial Team
REGENXBIO has completed dosing in the confirmatory portion of its AFFINITY DUCHENNE® program evaluating RGX-202, an investigational gene therapy for Duchenne muscular dystrophy (DMD). The study finished enrollment earlier than expected, driven by strong patient demand and investigator participation, positioning the company to submit a Biologics License Application (BLA) under the FDA’s accelerated approval pathway in the third quarter of 2026.
The planned regulatory submission will include safety data from 63 participants enrolled across the pivotal and confirmatory portions of the AFFINITY DUCHENNE study (NCT05693142), along with efficacy findings from the 30-patient pivotal cohort. REGENXBIO expects to provide 12-month functional outcomes for at least half of the pivotal-study participants at the time of filing.
RGX-202 Targets the Root Cause of Duchenne Muscular Dystrophy
Duchenne muscular dystrophy is a rare, progressive genetic disorder caused by mutations in the dystrophin gene. The absence of functional dystrophin leads to continuous muscle degeneration, loss of mobility, respiratory complications, cardiomyopathy, and premature death. The disease affects approximately one in every 3,500 to 5,000 boys born worldwide.
RGX-202 delivers a novel microdystrophin transgene using adeno-associated virus (AAV) gene therapy technology. Unlike other microdystrophin constructs, RGX-202 includes the C-terminal domain, a region believed to play an important role in preserving muscle structure and function. The therapy also incorporates a proactive immune suppression regimen and a manufacturing process intended to support high product purity and dosing consistency.
Pivotal Study Demonstrated Strong Biomarker and Functional Results
In recently reported topline data, RGX-202 met its primary endpoint, achieving at least 10% microdystrophin expression at Week 12 in more than 93% of treated patients.
Interim efficacy findings from patients who completed 12 months of follow-up (n=9) showed meaningful improvements across multiple timed function assessments and the North Star Ambulatory Assessment (NSAA), a widely used measure of motor function in ambulatory boys with Duchenne.
Investigators also observed a strong correlation between Week 12 microdystrophin expression and functional improvements at one year. These findings support microdystrophin expression as a surrogate endpoint reasonably likely to predict clinical benefit, a key consideration for accelerated approval.
The therapy was generally well tolerated and maintained a favorable safety profile across the study population.
Accelerated Approval Strategy Gains Momentum
Chief Executive Officer Curran Simpson said the completion of the confirmatory study highlights the significant unmet medical need in Duchenne and strengthens the company’s position for an accelerated approval filing. He noted that recent FDA interactions across rare disease programs reinforce continued regulatory support for the accelerated approval pathway when supported by meaningful biomarker and clinical data.
Regulatory Filing Expected in Q3 2026
REGENXBIO plans to initiate its BLA submission in the third quarter of 2026. If approved, RGX-202 could become the next gene therapy available for Duchenne muscular dystrophy patients in the United States.
To support potential commercialization, the company has already begun producing commercial-intended supply at its Manufacturing Innovation Center in Maryland. With confirmatory enrollment completed and pivotal data continuing to mature, the focus now shifts to regulatory review and long-term durability outcomes that could further establish RGX-202’s clinical value in Duchenne.
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About the Writer
Fariha Sameen, PharmD (LinkedIn), is a clinical pharmacy professional with hands-on experience in patient counselling, medication review, therapeutic monitoring, and clinical documentation across multiple departments. She has experience identifying and assessing drug-related problems and supporting medication safety practices. Her interests include pharmacovigilance, ADR reporting, clinical research, and medical writing focused on clear, evidence-based communication.