REGENXBIO Inc. reported additional interim safety and efficacy data in the Phase I/II AFFINITY DUCHENNE trial of RGX-202 in patients with Duchenne muscular dystrophy (Duchenne) ages 4 to11 years old, including RGX-202 microdystrophin expression from dose level 2 and video of trial clinic assessments demonstrating initial evidence of strength and functional improvement. Time of post-administration follow up ranges from approximately seven weeks to over eleven months. All patients who reached three-month follow-up have completed the immunosuppression regimen per study protocol.

In new data from the first patient, aged 12.1 years, who received RGX-202 at dose level 2, RGX-202 micrody Strophin expression was measured to be 75.7% compared to control at three months. Among patients aged 8 to 11 years old at screening, RGX-202 microdsytrophin expression levels (change from baseline) at three months following RGX-202 administration was higher in dose level 2. The patient data is presented below. In addition, new recordings of the AFFINITY DUCHenNE trial clinic assessments and home videos shared with trial investigators by caregivers illustrate patients treated with RGX-202 are demonstrating initial evidence of strength andfunctional improvement.

The company plan to present strength and functional assessment data for both dose levels from the trial later this year, but the company plan to present strength andfunctional assessment data for both dose levels of the trial later this year, the company expects to make a pivotal dose determination in mid-2024. RGX-202 is designed to support the delivery and targeted expression of genes throughout skeletal and heart muscle using theNAV 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, the company's future operations, clinical trials, costs and cash flow.

However, whether actual results and developments will conform with the company'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 clinical trials conducted by REGENXBIO, its licensees and its partners, the timing of commencement and completion and the success the success of preclinical studies conducted by REGENXBI O and its development partners, the timely development and launch of new products, the ability to obtain and maintain regulatory approval of product candidates, the ability to obtain and maintaining intellectual property protection for product candidates and technology, trends and challenges in the business and markets in which REGENXBIO operates, the size and growth of potential markets in which REGENX BIO operates, the size and development of potential markets, and the company expects to initiate pivotal trial in second half of 2024. The company expects to initiate pivotal trial to initiate pivotal trial in Second half of 2024. The trial is expected to initiate pivotal trial in second quarter of 2024.

The company expects the pivotal trial in second half of 2022. The company expects to make a pivotal doses determination in mid-20 2024. RGX-202 isdesigned to support the delivery and targeted expressions of genes throughout skeletal and heart Muscle using the NAV8 vector, a vector use in numerous clinical trials, and an well-characterized muscle- specific promoter (Spc5- 12).

The forward-looking statements includes statements relating to, among other Things, the size and growth of potentially potential markets, including the size and growth of potential market opportunities, including the potential markets, and the company's potential markets.