お知らせ • Mar 12
Regenxbio Inc Reports New Positive Interim Data From Phase I/II Affinity Duchenne Trial Of RGX-202
REGENXBIO Inc. announced new positive interim data from the Phase I/II AFFINITY DUCHENNE trial of RGX-202, a potential best-in-class gene therapy for Duchenne muscular dystrophy. Trial investigator Carolina Tesi-Rocha, M.D., Clinical Professor, Neurology, Stanford School of Medicine, Stanford Children's Health, is presenting this data, including new functional, safety, biomarker, and cardiac MRI measures, at the Muscular Dystrophy Association (MDA) Clinical and Scientific Conference. Investigational RGX-202 continues to demonstrate evidence of positively changing disease trajectory for Duchenne. Pivotal dose participants exceeded external controls across functional measures at 1 year, including participants aged 8+. Cardiac MRI data for pivotal dose patients demonstrated stability at 1 year. Favorable safety profile continued with no serious adverse events or adverse events of special interest observed in Phase I/II study. New data from multiple measures supported liver safety in pivotal patients. Pivotal topline data expected Second Quarter 2026. AFFINITY DUCHENNE Phase I/II Interim Data Updates (data cut: January 5, 2026): In the interim functional results from seven participants treated at the pivotal dose level (2x1014 GC/kg), aged approximately 6 to 12 years at dosing, RGX-202 continues to demonstrate evidence of positively impacting disease trajectory on North Star Ambulatory Assessment (NSAA) and all timed function tests (Time to Stand, 10 Meter Walk-run, Time to Climb) at one year. Functional outcomes were analyzed using multiple validated methods to estimate expected disease progression without treatment, including the cTAP disease progression model and external control comparisons using coarsened exact matching and propensity score weighting. Propensity score weighting is the primary analysis method specified in the SAP for the pivotal trial. The pivotal dose participants demonstrated improved performance across all timed function tests and NSAA when compared to external control using propensity score weighting. The 95% confidence interval demonstrates favorability to RGX-202. On NSAA, pivotal dose participants exceeded expected disease trajectory and external controls. Five of the seven participants were aged 8+ at dosing, when functional decline is expected. At one year, participants (n=7) improved an average of +4.9 points compared to cTAP. The older participants (n=5) improved an average of +5.2 points compared to cTAP. Additionally, dose level 1 (1x1014 GC/kg) participants (n=3) exceeded expected disease trajectory and improved an average of +5.6 points compared to cTAP at two years. Pivotal dose participants demonstrated cardiac stability at one year post-treatment as measured by MRI endpoints, including mean left ventricular ejection fraction, global circumferential strain, and fibrosis assessed by late gadolinium enhancement. Baseline: Subjects (N) 7, Age 8.7*, Mean (range) (5.8-12.1), Left Ventricular Ejection Fraction 61.7%, Mean (range) (54-72), Median 60%, Global Circumferential Strain -20.4%, Mean (range) (-22% to -19%), Median -20.4%, Late Gadolinium Enhancement (LGE) 1 participant with fibrosis. 12 Months: Subjects (N) 7, Age 9.7, Mean (range) (6.8-13.1), Left Ventricular Ejection Fraction 61.6%, Mean (range) (57-74), Median 60%, Global Circumferential Strain -20.9%, Mean (range) (-23% to -17%), Median -21.5%, Late Gadolinium Enhancement (LGE) No change from baseline. Biomarker data from the Phase I/II study continues to support consistent, high expression and transduction of RGX-202 microdystrophin (n=13). New data from an additional patient, aged 3.6 at dosing, had a microdystrophin expression level of 51.2% at Week 12. The primary endpoint in the pivotal phase of AFFINITY DUCHENNE is the proportion of participants whose RGX-202 microdystrophin expression is >10% at Week 12. RGX-202 was appropriately localized to the sarcolemma, demonstrating that the differentiated construct with the inclusion of the C-Terminal (CT) domain is appropriately targeting the muscle. New interim safety data from all Phase I/II pivotal dose participants aged 1 to <12 years at dosing show no evidence of liver injury across multiple measures. Mean gamma-glutamyl transferase (GGT) and total bilirubin, recognized markers of liver inflammation in Duchenne, did not exceed the upper limit of normal up to two years post-treatment. A mean reduction in creatine kinase was observed at one year post-treatment (n=8) and supported by mean reductions in ALT (n=7), AST (n=7) and LDH (n=8). RGX-202 was well tolerated with no serious adverse events (SAEs) and no AEs of special interest (AESIs) in the Phase I/II study as of the data cut date (n=13). Common drug-related AEs included vomiting, fatigue, and nausea. All are typically anticipated with gene therapy administration. A proactive, short-course immune modulation regimen in combination with a differentiated construct and industry-leading product purity levels of more than 80% full capsids may contribute to a favorable safety profile for RGX-202. REGENXBIO expects to share topline pivotal data in early Second Quarter 2026 and request a pre-BLA meeting with the FDA in mid-2026. The Company continues to enroll approximately 30 participants aged 1+ in the confirmatory trial of RGX-202 and expects to have the majority of this trial enrolled at the time of BLA submission. RGX-202 is a potential best-in-class investigational gene therapy designed for improved function and outcomes in Duchenne. RGX-202 is the only gene therapy approved or in late-stage development for Duchenne with a differentiated microdystrophin construct that encodes key regions of naturally occurring dystrophin, including the C-Terminal (CT) domain. Additional design features such as codon optimization may potentially improve gene expression, increase protein translation efficiency and reduce immunogenicity. RGX-202 is designed to support the delivery and targeted expression of microdystrophin throughout skeletal and heart muscle using the NAV AAV8 vector and a well-characterized muscle-specific promoter (Spc5-12). RGX-202 is manufactured by REGENXBIO using its proprietary, high-yielding NAVXpress suspension-based platform process.
