GENGLYCOS (pariglasgene brecaparvovec-opnr)

Aug. 19, 2026: Ultragenyx Pharmaceutical (NASDAQ: RARE) said the FDA granted accelerated approval to GENGLYCOS (pariglasgene brecaparvovec-opnr; DTX401), its first gene therapy approval, for adult and pediatric patients age 8+ with glycogen storage disease type Ia (GSDIa). The labeled indication is to reduce daily cornstarch intake as an adjunct to nutritional management.

Approval was supported by the 48-week randomized, double-blind, placebo-controlled Phase 3 GlucoGene study in 46 participants age 8+; in the modified ITT population (DTX401 n=20, placebo n=24), DTX401 significantly reduced cornstarch requirements versus placebo (p<0.001). Participants crossed over at Week 48, with follow-up analyses at Weeks 96 and 144.

As a condition of accelerated approval, Ultragenyx will provide two years of safety/efficacy data from open-label commercial treatment of 50 patients plus 20 controls through its existing GSDIa Disease Monitoring Program, and will follow previously treated trial participants and new commercial patients for 10 years. The company also received a Priority Review Voucher upon approval.

Safety information in the release includes serious adverse events during Weeks 1-48 such as anaphylaxis/infusion reactions, adrenal insufficiency, high lactate, and hypoglycemia; common adverse reactions included elevated ALT/AST (71%), nausea (38%), hypertriglyceridemia (29%), headache (24%), and adrenal insufficiency (24%).