FDA Delays Approval For Ultragenyx's Gene Therapy, But Not A Dealbreaker, Says Analyst

The U.S. Food and Drug Administration issued on Friday a Complete Response Letter for Ultragenyx Pharmaceutical Inc.’s RARE Biologics License Application (BLA) for UX111 (ABO-102) AAV gene therapy for Sanfilippo syndrome type A (MPS IIIA). 

In the CRL, the FDA requested that the company provide additional information and improvements related to specific aspects of CMC and observations from the recently completed manufacturing facility inspections.

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The company believes that these observations are readily addressable, related to facilities and processes, and are not directly related to the quality of the product.

The company will work with the FDA over the next few months to resolve the observations. Once resolution is achieved, the company expects to resubmit the BLA and anticipates a six-month review period following the resubmission.

The CRL did not note any review issues related to the clinical data package or clinical inspections and asked that updated clinical data from current patients be included in the resubmission.

William Blair sees the CRL as another unfortunate setback for the company. “However, UX111 revenue is not central to our investment thesis,” the analyst wrote.

Analyst Sami Corwin says it’s not unusual for gene therapies to receive CRLs due to chemistry, manufacturing and controls (CMC) issues — especially for those made outside the body (ex-vivo).

While Corwin believes the FDA’s concerns can likely be addressed quickly, the timeline for resolving the CRL and resubmitting the Biologics License Application (BLA) is uncertain.

This delay could also impact the BLA submission for DTX401, a treatment for glycogen storage disease type Ia (GSDIa).

It’s unclear whether the FDA's request for updated data from current UX111 patients will significantly delay the BLA resubmission. Although this could increase the risk of losing the Priority Review Vouchers (PRVs) tied to the approvals of UX111 and DTX401 — which must be approved before October 2026 under current law — the company believes it can still file both applications in time to retain the PRVs.

Wedbush maintains Ultragenyx with a Neutral, lowering the price target from $35 to $34.

Morgan Stanley maintains Ultragenyx with an Overweight, lowering the price target from $65 to $55.

RARE Price Action: Ultragenyx stock is up 0.88% at $29.77 at publication on Monday.

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