Ultragenyx Pharmaceutical has announced that the US FDA has accepted a priority review for its groundbreaking gene therapy.

 

The Biologics License Application (BLA) is for DTX401 AAV gene therapy (pariglasgene brecaparvovec), aimed at treating Glycogen Storage Disease Type Ia (GSDIa), a rare, life-threatening genetic disorder caused by mutations in the G6PC gene.

 

The FDA granted Priority Review and set a Prescription Drug User Fee Act (PDUFA) action date of August 23, 2026.

 

“Current dietary approaches to managing GSDIa place an extraordinary burden on individuals and families while still leaving patients with significant medical needs, including the risk of potentially life-threatening episodes of acute hypoglycemia and accumulation of long-term complications over their lifetime,” said Eric Crombez, chief medical officer at Ultragenyx. 

 

“If approved, DTX401 would be the first treatment to address the disease at its root cause. We appreciate the FDA’s timely acceptance of the BLA and will continue to work with the Agency throughout its review process.”

 

The application is backed by a robust clinical program involving 52 treated patients with up to six years of follow-up. Data from the Phase 3 GlucoGene study, a randomized, double-blind, placebo-controlled trial, show that patients treated with DTX401 experienced substantial reductions in both the amount and frequency of daily cornstarch intake while maintaining low hypoglycemia levels, improved euglycemia, and enhanced fasting tolerance. 

 

These outcomes also translated into significant improvements in patient-reported quality of life, as measured by the Patient Global Impression of Change (PGIC) scale. DTX401 was reported to be well tolerated with an acceptable safety profile.

 

If approved, DTX401 will be manufactured entirely in the U.S. at Ultragenyx’s new gene therapy facility in Bedford, Massachusetts.

 

DTX401 is an investigational AAV8 gene therapy designed to deliver stable expression and activity of G6Pase under its native promoter, allowing liver cells to respond to normal glucose-regulating hormones like insulin and cortisol.