RGNX · REGENXBIO Inc.

REGENXBIO's 8-K discloses transformative Phase III data for RGX-202, its gene therapy for Duchenne muscular dystrophy, marking a potential best-in-class treatment. The AFFINITY DUCHENNE trial met its primary endpoint at Week 12 with high statistical significance, driven by 93% of 30 participants achieving over 10% microdystrophin expression, including 80% above 40%, with appropriate sarcolemma localization due to the unique C-Terminal domain. Interim functional data from nine patients aged 5-12 showed statistically significant NSAA improvements versus external controls and strong correlation with microdystrophin levels, validating the surrogate endpoint per FDA discussions. Safety was favorable with a proactive immune suppression regimen and high-purity manufacturing (>80% full capsids), showing no elevated liver markers and only two resolved serious events: subacute myocarditis and asymptomatic liver injury. This supports REGENXBIO's accelerated approval strategy, with FDA open to external controls for large effects, and plans for BLA submission targeting 2027 launch. Dosing completion across 60 patients expected mid-year, plus ex-U.S. study design. Pipeline momentum includes AbbVie-partnered surabgene lomparvovec advancing to pivotal readouts and RGX-121 hold lift. Q1 2026 financial results were released alongside, with webcast discussing drivers. CEO Curran Simpson highlighted late-stage milestones positioning for first-in-class therapies in rare diseases.