REGENXBIO Inc. announced that enrollment has completed at dose level 2 and reported additional interim safety and efficacy in the Phase I/II AFFINITY DUCHENNE trial of RGX-202 in patients with Duchenne muscular dystrophy (Duchenne) ages 4 to11 years old. Time of post-administration follow up ranges from approximately three weeks to over nine months. All patients who reached three-month follow-up have completed the immunosuppression regimen per study protocol.

In new data from the third patient, aged 6.6 years, who received RGX-202 at dose level 1, RGX-202 microdystrophin expression was measured to be 83.4% compared to control at three months. A reduction from baseline in serum creatinine kinase (CK) levels of 93% was observed at ten weeks. The mean (SD) RGX-202 microdsytrophin expression levels (change from baseline) at three months following RGX-202 administration were 44.4% (n=3, SD:36.5%).

The patient data is presented below. Patient Age at Weight at Western blot (Jess method), CK Levels, Dosing (years) Dosing (kg) week 10 (% reduction from baseline). RGX-202 is designed to support the delivery and targeted expression of genes throughout skeletal and heart muscle using the NAV AAV8 vector, a vector used in numerous clinical trials, and a well-characterized muscle-specific promoter (Spc5-12).

The forward-looking statements include statements relating to, among other things, REGENXBIO's future operations, clinical trials, costs and cash flow. However, whether actual results and developments will conform with REGENXBIO's expectations and predictions is subject to a number of risks and uncertainties, including the timing of enrollment, commencement and completion and the success of preclinical studies conducted by REGENXBIO and its development partners, the timely development and launch of new products, the time development and launch of new products.