RARE Reports New Upbeat Data From Sanfilippo Syndrome Drug Study

Core Insights - Ultragenyx Pharmaceutical reported promising findings from its pivotal study of UX111, a gene therapy for Sanfilippo syndrome type A (MPS IIIA) [1][2][8] Clinical Findings - The phase I/II/III Transpher A study showed statistically significant improvements in cognitive and communication skills in MPS IIIA patients treated with UX111, alongside a notable reduction in cerebrospinal fluid (CSF) heparan sulfate levels [2][3] - Treatment with UX111 resulted in a median CSF-HS reduction of 65% across all treated patients and 66% in the modified intention-to-treat (mITT) group, with an average follow-up duration of 34 months [3] - All 10 patients excluded from the mITT group due to older age or advanced disease retained meaningful functional abilities, which is significant as such functions typically deteriorate in late childhood and early adolescence [5] Safety Profile - All doses of UX111 were reported to be generally safe and well-tolerated, with treatment-related adverse events mostly mild to moderate in severity [6] Regulatory Developments - Ultragenyx submitted a biologics license application (BLA) to the FDA for UX111 under the accelerated approval pathway, with a final decision expected in the second half of 2025 [8][9] - If approved, UX111 will be the first FDA-approved therapy for MPS IIIA in the United States, affecting approximately 3,000 to 5,000 patients [9] Pipeline Overview - Ultragenyx has several other gene therapy candidates in its pipeline, including UX143 for osteogenesis imperfecta and UX701 for Wilson disease, with various stages of development and regulatory designations [11][12][13] Market Performance - In the past three months, shares of Ultragenyx (RARE) have declined by 10%, compared to an 8.7% decline in the industry [4]