Ultragenyx released additional long‑term clinical and biomarker data for UX‑111 (rebisufligene etisparvovec), its AAV9 gene therapy for Sanfilippo syndrome type A, reporting consistent and statistically significant biomarker improvements and functional benefits across age and disease severity. The company says UX‑111 remains well tolerated and has resubmitted the BLA after addressing prior CMC deficiencies. Ultragenyx expects a PDUFA window in the third quarter of 2026 and will present data at upcoming scientific meetings. The new dataset is intended to support the FDA’s reconsideration and to strengthen the therapy’s risk‑benefit case in a disease with high unmet need.