REGENXBIO Inc. has announced positive topline and interim functional data from the pivotal Phase III portion of the Phase I/II/III AFFINITY DUCHENNE® trial of RGX-202, an investigational gene therapy being developed for individuals with Duchenne muscular dystrophy. RGX-202 is designed to deliver a microdystrophin via AAV8 through a one-time IV infusion.
The newly released data comes from ambulatory individuals treated at a 2×1014 GC/kg dose. According to REGENXBIO, the trial met its primary endpoint of at least 10% microdystrophin expression at week 12, with 93% of participants reaching that threshold at week 12 (n=30). The company also shared that 80% of individuals had >40% microdystrophin expression and that RGX-202 was appropriately localized to the sarcolemma.
Additionally, REGENXBIO notes that RGX-202 microdystrophin expression demonstrated statistically significant correlation with functional improvement at one year as measured by North Star Ambulatory Assessment (NSAA) change from baseline (in 9 individuals aged 5-12 years old). Results also indicate a favorable safety profile and positive biomarker data.
According to REGENXBIO, the FDA has indicated that the use of RGX-202 microdystrophin expression as a surrogate endpoint will be based on the correlation analysis with clinical outcomes (e.g. does microdystrophin expression correlate to changes in NSAA), and that externally controlled trials may be adequate for demonstrating substantial evidence of effectiveness. The company plans to discuss this data with the FDA at a future meeting and pursue accelerated approval for RGX-202.
PPMD is pleased to learn this news. “For decades, our community has pushed for therapies that can change the trajectory of this disease, and today’s news gives us renewed optimism,” said PPMD’s Pat Furlong. We applaud the dedication of the patients and families who participated in this research, and look forward to further updates from REGENXBIO.
Read REGENXBIO’s press release here. Read the company’s community letter below:
May 14, 2026
Dear Duchenne Community,
We are pleased to share an update on the AFFINITY DUCHENNE® trial of RGX-202*, REGENXBIO’s investigational gene therapy for Duchenne muscular dystrophy.
This morning, REGENXBIO shared positive topline and interim functional and safety data from the pivotal Phase III portion of the trial. You can read more about this update in our press release.
RGX-202 is designed to deliver a novel microdystrophin protein that includes the C- Terminal (CT) domain found in naturally occurring dystrophin. The pivotal Phase III portion of the AFFINITY DUCHENNE study evaluated RGX-202 in 31 participants.
The trial met its primary endpoint, with 93% of participants achieving greater than 10% microdystrophin expression at Week 12. In 9 participants who reached one year post- dosing, functional improvement (changes from baseline) were demonstrated on the NSAA and timed function tests. RGX-202 was also well tolerated to date.
Additionally, we were encouraged to see that among the 9 participants with one year of follow-up, microdystrophin expression levels were statistically significantly correlated with NSAA change from baseline.
These AFFINITY DUCHENNE data support our plans to file a Biologics License Application in the U.S. using the FDA’s accelerated approval pathway in 2027.
To learn more about our work, visit regenxbiodmdtrials.com.
We extend our sincere thanks to the patients, families and investigators who are participating in our clinical trial. Your participation continues to guide our work and help advance research for Duchenne. If you have questions, please email us at duchenne@regenxbio.com.
Sending our best wishes on behalf of the Team at REGENXBIO,
Naz Dastgir, DO, Executive Director, Clinical Development
Vivian Fernandez, Executive Director, Patient Advocacy
The post REGENXBIO Shares Topline Results from Pivotal Phase III AFFINITY DUCHENNE® Study of RGX-202 appeared first on Parent Project Muscular Dystrophy.