Company: RGNX
Filing Date: 2025-03-13
Form Type: 10-K
Source: 0000950170-25-038770
Chunk: 82

Company: REGENXBIO Inc.
Filing Date: 2025-03-13
Form: 10-K
Item: Item 1
Chunk 82
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 and premature death. There is presently no cure for Duchenne, and there is a significant unmet need for disease modifying treatment options. Duchenne is one of the most common fatal genetic disorders affecting children, primarily boys. Duchenne is estimated to occur in approximately one in every 3,500-5,000 live male births and has an estimated prevalence of more than 30,000 cases in the U.S., Europe and Japan. 

RGX-202 is designed to deliver a transgene for a novel microdystrophin that includes the functional elements of the C-Terminal (CT) domain found in naturally occurring dystrophin. Presence of the CT domain has been shown in preclinical studies to recruit several key proteins to the muscle cell membrane, leading to improved muscle resistance to contraction-induced muscle damage in dystrophic mice. Additional design features may potentially improve gene expression, increase translational efficiency and reduce immunogenicity. RGX-202 is designed to support the delivery and targeted expression of the transgene throughout skeletal and heart muscle using the NAV AAV8 vector, and a well-characterized muscle-specific promoter (Spc5-12).

We have received orphan drug product, Fast Track designation and rare pediatric disease designation from the FDA for RGX‑202.

Clinical Development of RGX-202

AFFINITY DUCHENNE® is a multicenter, open-label Phase I/II/III trial of RGX-202 in ambulatory patients aged one and older. Patients receive a dose of 2x1014 GC/kg. The pivotal phase of the trial is expected to support a BLA submission using the accelerated approval pathway in 2026.

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To support potential accelerated approval, the primary endpoint is the proportion of participants whose RGX-202 microdystrophin expression is ≥ 10% at Week 12. Secondary endpoints include change from baseline on timed function tests including time to stand, 10 meter walk/run and time to climb in participants ages 4 and older. Participants aged 1 to < 4 years will be evaluated using the Peabody Developmental Motor Scale-Third Edition and stride velocity 95th centile. Patients will be assessed on the North Star Ambulatory Assessment (NSAA) as an exploratory endpoint.

In March 2024 and May 2024, we reported interim safety and efficacy data from the Phase I/II portion of the trial, including positive RGX-202 microdystrophin expression results for the first two patients who received RGX