Ultragenyx disclosed new long‑term clinical data for UX‑111 (rebisufligene etisparvovec), an AAV9 gene therapy for Sanfilippo syndrome type A, showing durable biomarker improvements and meaningful functional benefits across ages and disease severities. The company resubmitted its BLA to the FDA after addressing manufacturing and CMC issues and expects a PDUFA date in the third quarter of 2026. Company statements emphasized consistent statistical benefit versus natural history controls and a favorable safety profile. Ultragenyx plans to present the expanded dataset at an upcoming scientific meeting and is positioning the resubmission as supported by longitudinal outcomes and improved CMC documentation.