Breaking: FDA Agrees Heparan Sulfate is a Reasonable Surrogate Endpoint for UX111

June 12, 2024


Ultragenyx Pharmaceutical Inc. announced just minutes ago that it held a successful meeting with the U.S. Food and Drug Administration (FDA), during which they reached agreement that cerebral spinal fluid (CSF) heparan sulfate (HS) 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 FDA in a pre-BLA meeting. Ultragenyx intends to file a BLA in late 2024 or early 2025.

This is a massive “interim win” for the entire Sanfilippo Syndrome community (and by extension more broadly for patients with neurodegenerative forms of MPS). Establishing cerebral spinal fluid heparan sulfate as a reasonable surrogate endpoint will have a significant impact on the development of therapies aiming to treat the underlying enzyme deficiency of Sanfilippo.

This major milestone in FDA decision-making comes on the heels of the February 2024 workshop hosted by the Reagan Udall Foundation regarding “Developing Biomarkers to Support Accelerated Approval in Rare Diseases.” Cure Sanfilippo Foundation were among the organizations and industry experts urging the FDA to recognize the scientific relevance and utility of cerebrospinal fluid heparan sulfate, as a primary biomarker to support accelerated approval in the neuronopathic MPS disorders.

“This is one of the major barriers we have all been working so hard together to overcome,” said Cara O’Neill, Co-Founder and Chief Science Officer of Cure Sanfilippo Foundation and mother of Eliza. “Thanks to the many families, partners, and supporters who we walk forward with. We hope this is the beginning of heralding change in the way ultra rare disease treatments are developed for children in such great need.”

Cure Sanfilippo Foundation’s donors provided a significant early investment in the development of this treatment through the initial sponsor Abeona Therapeutics and academic study site in the US, along with many other co-funding organizations in the community.

“While drug development never moves as fast as this disease necessitates, we must recognize the important progress that has been made over the past decade,” said O’Neill. “Our thanks go out to Ultragenyx for picking up the program and continuing to push forward. With hope!”

Read Ultragenyx complete press release for more information.

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