On June 12, 2024, Ultragenyx Pharmaceutical Inc. announced that the Company held a successful meeting with the U.S. Food and Drug Administration during which the Company reached agreement with the Agency that cerebral spinal fluid heparan sulfate is a reasonable surrogate endpoint that could support submission of a biologics license application ("BLA") seeking accelerated approval for UX111 (ABO-102) AAV gene therapy for the treatment of Sanfilippo syndrome ("MPS IIIA"). The Company will need to finalize details of its BLA with the Agency in a pre-BLA meeting with the intent to file late this year or early next year. As discussed with the FDA, the BLA filing will be based on the available data including from the ongoing pivotal Transpher A study evaluating the safety and efficacy of UX111 in children with MPS IIIA.

Results from the Transpher A and long-term follow-up studies were recently presented at the 20th Annual WORLDSymposium.