Ultragenyx Pharmaceutical Inc. filed an 8-K with the U.S. Securities and Exchange Commission on August 19, 2026, announcing that the FDA granted accelerated approval for GENGLYCOS (pariglasgene brecaparvovec-opnr) in adult and pediatric patients eight years and older with glycogen storage disease type Ia.

Key Highlights

  • FDA Accelerated Approval: GENGLYCOS (also known as DTX401) received accelerated approval for GSDIa in patients aged eight years and older.
  • Phase 3 Trial Basis: Approval is based on data from the 48-week randomized, double-blind, placebo-controlled GlucoGene study involving 46 participants.
  • Statistically Significant Result: The treated group showed a reduction in cornstarch requirements versus placebo (p<0.001).
  • Post-Marketing Commitment: Ultragenyx agreed to provide two years of safety and efficacy data from open-label commercial treatment of 50 patients and 20 control patients.
  • Long-Term Follow-Up: The Disease Monitoring Program will evaluate previously treated trial participants and new commercial patients for a total of 10 years.

GENGLYCOS Approval Details and Post-Marketing Requirements

According to the filing, the FDA granted accelerated approval for GENGLYCOS on August 19, 2026. The therapy, pariglasgene brecaparvovec-opnr, is indicated for adult and pediatric patients eight years and older with glycogen storage disease type Ia (GSDIa). Ultragenyx Pharmaceutical Inc. (NASDAQ:RARE) disclosed the approval in a current report filed under Item 8.01 (Other Events).

The company disclosed that approval was supported by the GlucoGene Phase 3 study, a 48-week randomized, double-blind, placebo-controlled trial. The study treated 46 participants with DTX401 at a dose of 1.0 x 10^13 GC/kg or placebo. The modified intention-to-treat population included 44 participants, with 20 receiving DTX401 and 24 receiving placebo. At Week 48, eligible participants crossed over to receive the alternate treatment, with subsequent analyses conducted at Week 96 and Week 144, according to the filing.

As a condition of accelerated approval, the filing states that Ultragenyx has agreed to provide two years of safety and efficacy clinical data drawn from open-label commercial treatment of 50 patients and 20 control patients, channeled through an enhancement of its existing GSDIa Disease Monitoring Program (DMP). The filing notes the control group will consist of patients who sought commercial treatment but cannot receive GENGLYCOS due to the presence of anti-AAV8 antibodies. The DMP will also evaluate previously treated clinical trial participants alongside new commercial patients for a total of 10 years.

What Was Disclosed

Ultragenyx filed an 8-K on August 19, 2026, reporting FDA accelerated approval of GENGLYCOS for GSDIa in patients eight years and older, along with the Phase 3 data supporting approval and the post-marketing study commitments required by the FDA.