REGENXBIO has initiated the pivotal Phase III trial for its gene therapy candidate, RGX-202, targeting Duchenne muscular dystrophy (DMD). This advancement follows promising outcomes from the Phase I/II trial, leading to FDA approval for expansion into a Phase I/II/III study and access to the accelerated approval pathway. The company anticipates filing a Biologics License Application (BLA) in 2026.
RGX-202: A Novel Approach to DMD Treatment
RGX-202 is an investigational gene therapy employing a unique microdystrophin construct. Data from the Phase I/II trial indicated that recipients of RGX-202 exhibited superior clinical outcomes compared to natural history benchmarks. Functional improvements were observed in all patients treated with both dose levels at 12 and nine months, respectively, alongside a positive safety profile.
Competitive Landscape
This progress positions REGENXBIO as a significant competitor to Sarepta Therapeutics, whose gene therapy Elevidys (delandistrogene moxeparvovec-rokl) has already received FDA approval. Sarepta reported $190.5 million in worldwide sales for Elevidys in its third-quarter earnings report.
Expert Commentary
Aravindhan Veerapandiyan, MD, a child neurologist at Arkansas Children’s Hospital, stated, “There remains a critical need for new therapeutic options for patients with Duchenne muscular dystrophy. I am very pleased to see the advancement of the RGX-202 program to the pivotal stage, which offers promise for a broader patient population and am highly encouraged by the functional data presented today demonstrating RGX-202’s potential to alter the course of the disease. The safety, functional, and biomarker data shared today reinforce the positive feedback from families, highlighting improvements in patients’ daily activities and underscoring the potential benefits of this treatment.”
Clinical Trial Data
Specialized testing revealed improvements in patient function. Across both dose levels in the Phase I/II trial, RGX-202 positively influenced the disease trajectory in all five participants. Patients demonstrated stable or improved function on the North Star Ambulatory Assessment (NSAA) and timed function tests, when measured against external natural history controls matched for age and baseline function. Patients receiving the higher dose exhibited improved performance on NSAA and timed function tests at nine months, surpassing natural history controls. The NSAA mean score at this dose improved by 5.5 points.
Biomarker Data
REGENXBIO also presented new biomarker data indicating consistent, high expression and transduction of RGX-202 microdystrophin. The therapy was appropriately localized to the sarcolemma, indicating effective targeting of the muscle. In patients aged eight and older, the highest reported levels of microdystrophin expression were observed compared to other approved or investigational gene therapies for DMD.
Company Statements
Curran M. Simpson, president and CEO of REGENXBIO, commented, “The initiation of our pivotal trial and newly released positive functional data are exciting milestones on our path to rapidly deliver RGX-202, the only next generation gene therapy in pivotal phase, to the Duchenne community. The totality of our data demonstrates that RGX-202 provides evidence of improving outcomes for boys with Duchenne and altering the trajectory of this devastating disease, with consistent, robust expression of our novel microdystrophin translating into significant clinical benefit.”
Simpson added, “Based on the strength of the Phase I/II data and our positive discussions and alignment with the FDA, we are quickly advancing RGX-202 toward a BLA filing in 2026 using the accelerated approval pathway. We continue to evaluate opportunities to expand the RGX-202 program to benefit Duchenne patients worldwide.”
