Ultragenyx Pharmaceutical Inc. shares surged 14% in after-hours trading on Wednesday following the U.S. Food and Drug Administration’s accelerated approval of its gene therapy for glycogen storage disease type Ia (GSDIa).
The FDA granted approval for GENGLYCOS, also known as DTX401, the company’s first gene therapy and its fifth overall FDA authorization. The approval includes a Priority Review Voucher, a regulatory incentive typically awarded for significant drug approvals.
GSDIa is an ultra-rare genetic metabolic disorder affecting an estimated 1,500 to 2,500 patients in the U.S. The condition results from a deficiency in the enzyme required to release glucose from the liver into the bloodstream. Patients currently manage the disease with continuous raw cornstarch intake to prevent life-threatening hypoglycemia episodes.
The FDA’s decision was based on data from the 48-week Phase 3 GlucoGene study, which enrolled 46 participants aged eight years and older. The trial, designed as a randomized, double-blind, placebo-controlled study, demonstrated a reduction in cornstarch requirements for patients treated with DTX401 compared to placebo.
GENGLYCOS is approved for use in adult and pediatric patients eight years and older. Distribution will occur through a national network of Qualified Treatment Centers with specialized expertise in gene therapy administration. The therapy is manufactured at Ultragenyx’s Gene Therapy Manufacturing Facility in Bedford, Massachusetts.
As part of the accelerated approval pathway, Ultragenyx committed to providing two years of safety and efficacy clinical data from open-label commercial treatment of 50 patients and 20 control patients through its existing GSDIa Disease Monitoring Program. The control group will include patients ineligible for GENGLYCOS due to anti-AAV8 antibodies.
