Ultragenyx's UX111 Gene Therapy Approval Delayed by FDA Until 2026

Ultragenyx Pharmaceuticals has received a Complete Response Letter from the FDA for its UX111 AAV gene therapy, delaying potential approval to 2026. The FDA has requested additional information on manufacturing and processing areas observed during facility inspections. The company plans to resubmit the application once the issues are resolved and anticipates a six-month review period. The FDA's clinical review continues, noting the strength of neurodevelopmental outcome data and supportive biomarker evidence.

Ultragenyx Pharmaceuticals has received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA) for its UX111 AAV gene therapy, delaying potential approval to 2026. The CRL cited specific chemistry, manufacturing, and controls (CMC) related observations that are resolvable [2]. The FDA's clinical review acknowledged the robustness of the clinical data and supportive biomarker evidence, but requested additional information on manufacturing and processing areas observed during facility inspections.

The company plans to address the CMC observations and resubmit the Biologics License Application (BLA) as soon as possible. Ultragenyx anticipates a six-month review period following the resubmission. The FDA's clinical review continues, noting the strength of the neurodevelopmental outcome data and supportive biomarker evidence.

The CRL did not note any review issues related to the clinical data package nor clinical inspections. The company believes the CMC observations are readily addressable and many have already been addressed. The company will work with the FDA over the next few months to resolve the observations.

If approved, UX111 will be a novel in vivo gene therapy for Sanfilippo syndrome type A (MPS IIIA), a rare fatal lysosomal storage disease with no approved treatment that primarily affects the brain. The therapy addresses the underlying SGSH enzyme deficiency responsible for abnormal accumulation of heparan sulfate in the brain, resulting in progressive cell damage and neurodegeneration.

Ultragenyx is committed to bringing novel therapies to patients for the treatment of serious rare and ultra-rare genetic diseases. The company has built a diverse portfolio of approved medicines and treatment candidates aimed at addressing diseases with high unmet medical need and clear biology.

References:
[1] https://www.marketscreener.com/quote/stock/MERCK-CO-INC-13611/news/Merck-FDA-approval-for-Bravecto-Quantum-50488339/
[2] https://ir.ultragenyx.com/news-releases/news-release-details/ultragenyx-receives-complete-response-letter-fda-ux111-aav-gene