FDA Rejects Ultragenyx's Gene Therapy for Rare Disease - Sanfilippo Syndrome
- Thy TX NGUYEN
- Jul 16
- 1 min read
Updated: Aug 7
The FDA has declined to approve Ultragenyx Pharmaceutical's gene therapy, UX111, for treating Sanfilippo syndrome type A, a rare genetic disorder. The rejection, issued on July 11, 2025, was due to manufacturing concerns, not related to the quality of the therapy itself. This decision came ahead of the expected action date, causing Ultragenyx’s shares to drop by 5.4%.
Ultragenyx remains optimistic, noting that many of the FDA's concerns about manufacturing have already been addressed. The company plans to resubmit its application with updated clinical data. Experts believe this setback is a “speed bump” rather than a permanent roadblock, allowing the company a chance to fix the issues and move forward.
UX111 has shown promise in clinical trials, significantly reducing toxic buildup in the brain and improving cognitive and communication abilities in children. Despite the therapy's positive results, the FDA’s decision highlights the challenges in gene therapy production, which can complicate the approval process.
The rejection has put pressure on Ultragenyx to resolve the FDA’s concerns and resubmit the application. The company aims to provide additional trial data and expects a new review to take up to six months once the revised application is submitted.
Many in the rare disease community are closely watching as Ultragenyx navigates the regulatory hurdles. With no disease-modifying treatments for Sanfilippo syndrome type A, UX111 represents a crucial potential breakthrough for children affected by this severe condition.
Created: July 16th, 2025
Citations:
Choudhury, K. (2025, July 11). US FDA declines to approve Ultragenyx's gene therapy for rare genetic disorder. Reuters.
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