Ultragenyx Submits BLA for UX111 Gene Therapy

The BLA submission for UX 111 is supported by available data, including from the ongoing pivotal Transpher A study, demonstrating treatment with UX 111 resulted in rapid and sustained decreased levels of HS in CSF in patients with Sanfilippo syndrome type A, and that sustained reduction in CSF HS exposure over time was correlated with improved long-term cognitive development compared to the decline observed during the same period of time in natural history data. The most frequently reported treatment-related adverse events to date were elevations in liver enzymes, and the majority of these events were mild (Grade 1) or moderate (Grade 2) in severity and all resolved.

The path to get a treatment to the point of a BLA filing has been long and perilous for the Sanfilippo community. They have had to watch their children, once thriving, lose their ability to speak and walk, and eventually die, while research programs were shelved due to regulatory and funding hurdles,” said Dr. Emil D. Kakkis,  chief executive officer and president of Ultragenyx. “We commend the FDA’s detailed evaluation and acceptance of cerebral spinal fluid (CSF) heparan sulfate (HS) as a well-characterized biomarker to support an accelerated approval pathway for mucopolysaccharidoses (MPS) disorders, including Sanfilippo syndrome. The FDA’s acceptance of CSF HS, which we define as a disease-cause biomarker since it measures the underlying disease, enabled us to file our BLA and may unlock the future accelerated approvals of a host of new therapies for these devastating MPS diseases that affect the brain.”

Earlier this year, Ultragenyx reached agreement with the FDA that CSF HS can be used as a surrogate endpoint for accelerated approval based on the body of data presented by the company, along with a consortium of academics and other industry sponsors at a workshop hosted by the Reagan-Udall Foundation for the FDA in February 2024.