Ultragenyx Resubmits BLA for UX111 Gene Therapy for Sanfilippo Syndrome Type A to FDA
RARE sits 32% above its 52-week low of $18.41.
Summary
Ultragenyx Pharmaceutical has resubmitted its Biologics License Application (BLA) for UX111 gene therapy to the FDA, addressing prior regulatory concerns and including new long-term clinical data for Sanfilippo syndrome type A.
Key Events · Product Development and Regulatory · RARE
-
BLA Resubmission for UX111
Ultragenyx Pharmaceutical Inc. has resubmitted its Biologics License Application (BLA) for UX111 (rebisufligene etisparvovec) AAV9 gene therapy for Sanfilippo syndrome type A (MPS IIIA) to the U.S. Food and Drug Administration (FDA).
-
Addresses Prior Complete Response Letter (CRL)
The resubmission includes comprehensive responses to chemistry, manufacturing, and controls (CMC)-related observations outlined in a Complete Response Letter (CRL) issued in July 2025.
-
Includes Longer-Term Clinical Data
The filing contains substantial longer-term data on multiple measures of neurologic benefit and additional long-term clinical data from current patients, as requested by the FDA.
-
Potential First-in-Class Therapy
If approved, UX111 would be the first approved therapy for Sanfilippo syndrome type A, addressing a significant unmet medical need.
Analysis · RARE · Life Sciences
Ultragenyx Pharmaceutical's resubmission of the Biologics License Application (BLA) for UX111 is a critical step forward for a potential first-in-class gene therapy. The company has addressed the Chemistry, Manufacturing, and Controls (CMC) observations from the July 2025 Complete Response Letter (CRL) and included additional long-term clinical data. This move signals progress in overcoming prior regulatory hurdles and brings the company closer to potentially launching a significant treatment for Sanfilippo syndrome type A, a condition with no approved therapies. Investors should monitor the FDA's review process and the anticipated PDUFA action date in Q3 2026, as approval would unlock a new revenue stream and validate the company's gene therapy platform.
How filings like this one have moved
In the 30 days to Sep 14, 2026, 35.8% of the 1045 measured filings Wiseek scored 8 moved their stock by 5% or more by the next session's close. The median move was -0.43%. These are measured outcomes after filings of this importance, not a forecast for this one.
Measured one observation per ticker per day, after exclusions. Current figures: Filing Impact Tracker · open dataset
At the time of this filing, RARE was trading at $24.26 on NASDAQ in the Life Sciences sector, with a market capitalization of approximately $2.3B. The 52-week trading range was $18.41 to $46.50. This filing was assessed with positive market sentiment and an importance score of 8 out of 10.