Company: RGNX
Filing Date: 2025-06-25
Form Type: 424B3
Source: 0001193125-25-146911
Chunk: 2

Company: REGENXBIO Inc.
Filing Date: 2025-06-25
Form: 424B3
Chunk 2
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, current conditions and expected future developments, as well as other factors we believe are appropriate under the circumstances. However, whether actual results and developments will conform with our expectations and predictions is subject to a number of risks, uncertainties, assumptions and other important factors, including, but not limited to:

| • |     | our ability to establish and maintain development partnerships, including our collaboration with AbbVie Inc. to                  
 develop and commercialize ABBV-RGX-314 and our collaboration with Nippon Shinyaku Co., Ltd. to develop and commercialize RGX-121 
 and RGX-111;                                                                                                                     |

| • |     | our ability to obtain and maintain regulatory approval of our product candidates, and the labeling for any 
 approved products;                                                                                         |

| • |     | the timing of enrollment, commencement, completion and the success of our AAVIATE®, AFFINITY BEYOND®, AFFINITY DUCHENNE®, ALTITUDE®, ASCENT™, ATMOSPHERE® and 
 CAMPSIITE® clinical trials;                                                                                                                                   |

| • |     | the timing of commencement and completion and the success of preclinical studies conducted by us and our 
 development partners;                                                                                    |

| • |     | the timely development and launch of new products; |

| • |     | the scope, progress, expansion and costs of developing and commercializing our product candidates; |

| • |     | our ability to obtain, maintain and enforce intellectual property protection for our product candidates and 
 technology, and defend against third-party intellectual property-related claims;                            |

| • |     | our expectations regarding the development and commercialization of product candidates currently being developed 
 by third parties that utilize our technology;                                                                    |

| • |     | our anticipated growth strategies; |

| • |     | our expectations regarding competition; |

| • |     | the anticipated trends and challenges in our business and the market in which we operate; |

| • |     | our ability to attract or retain key personnel; |

| • |     | the size and growth of the potential markets for our product candidates and the ability to serve those markets; |

| • |     | the rate and degree of market acceptance of any of our products that are approved; |

| • |     | our expectations regarding our expenses and revenue; |

| • |     | our expectations regarding our need for additional financing and our ability to obtain additional financing; |

| • |     | our expectations regarding the outcome of legal proceedings; |

| •