MPS II DEVELOPING LIFE-CHANGING GENE THERAPIES MPS II Mucopolysaccharidosis Type II (MPS II), also known as Hunter syndrome, is a rare genetic disorder caused by mutation(s) in the gene that are responsible for making iduronate-2-sulfatase (IDS), an enzyme needed by cells to break down long chains of sugar molecules known as mucopolysaccharides. These sugar molecules are cellular waste products. As they build up in tissues, like the central nervous system (CNS), they cause progressive damage to these tissues and to many organs in the body, including the brain. In severe forms of MPS II, early developmental milestones in a child may be met, but delays become apparent by 18 to 24 months, with decline reported around six years of age. Children with MPS II may also show symptoms of severe behavioral effects. There remains a significant unmet medical need to prevent decline in cognition and other neurological aspects of the disease. Our investigational therapy, RGX-121, is designed to use the AAV9 vector to deliver the IDS gene directly to the CNS. We believe that once the AAV9 vector delivers the gene to cells, the cells can begin making the needed IDS enzyme, potentially preventing the onset and/or further progression of cognitive deficits. REGENXBIO has the following studies enrolling MPS II patients: Phase I/II clinical trial of RGX-121 in children 4 months to 5 years old This study aims to determine whether RGX-121 is safe, well-tolerated and potentially effective in children over four months and under the age of five years with severe MPS II. Learn more about this study: NCT03566043 Phase I/II clinical trial in children 5 years and older This study aims to determine whether RGX-121 is safe, well-tolerated, and potentially effective in children five years of age and over with severe MPS II. Learn more about this study: NCT04571970 Observational study of Pediatric MPS II patients This study will follow MPS II children who are between one month and eight years of age to document their cognitive, behavioral, and adaptive function over time. Some patients may be offered the opportunity to screen for other RGX-121 gene therapy studies. Learn more about this study: NCT04591834 Download Brochure On Gene Therapy In MPS DOWNLOAD Contact REGENXBIO Via Email CONTACT US Stay Updated On REGENXBIO Programs SUBSCRIBE SIGN UP Receive updates to stay connected on REGENXBIO programs and our commitment to patients. Subscribe CONTACT US 9804 Medical Center Drive, Rockville, MD 20850 240.552.8181 General Info | Medical Info | Patient Advocacy | Partners | Investors | Media FOLLOW US ©2021 REGENXBIO Inc. "NAV®" is a registered trademark of REGENXBIO Inc. All rights reserved. Privacy Policy | Terms and Conditions