GENGLYCOS (pariglasgene brecaparvovec-opnr)

September 1, 2026: Ultragenyx Pharmaceutical (NASDAQ: RARE) announced publication of 96-week Phase 3 GlucoGene data in The Journal of Inherited Metabolic Disease for GENGLYCOS/DTX401 (pariglasgene brecaparvovec-opnr) in glycogen storage disease type Ia (GSDIa). The company said GENGLYCOS was recently FDA-approved for patients aged 8 and older under accelerated approval to reduce daily cornstarch intake as an adjunct to nutritional management.

The Phase 3 study previously met its primary endpoint at Week 48: mean cornstarch reduction was 41% with DTX401 (n=20) versus 10% with placebo (n=24) (p<0.0001). By Week 96, both the original DTX401 group (n=20) and crossover group (n=19) showed mean 61% reductions from baseline; 67% and 72%, respectively, achieved at least 50% reduction.

Nighttime burden also improved: at Week 48, 50% of DTX401-treated patients eliminated at least one nighttime cornstarch dose versus 7% on placebo (p=0.031). By Week 96, 67% in both treated groups eliminated at least one nighttime dose, and complete elimination occurred in 33% of original DTX401 patients and 42% of crossover patients.

Patients maintained glycemic control, with low hypoglycemia levels, improved time in euglycemic range, and improved fasting tolerance. DTX401 was generally well tolerated; common treatment-related adverse events were transient liver enzyme elevations. Continued approval may depend on confirmatory trials.