Guess the Therapy Answer February 4, 2026

Which investigational gene therapy for Glycogen Storage Disease Type Ia did Ultragenyx recently finish submission of a BLA for?

Answer: DTX401

See below for further reading on DTX401:

Ultragenyx Finishes Rolling Submission of BLA for Glycogen Storage Disease Gene Therapy DTX401

Ultragenyx has completed its submission of a rolling biologics license application (BLA) to the FDA for DTX401, an investigational adeno-associated virus serotype 8 (AAV8) vector gene therapy expressing the human G6PC gene that is intended to treat Glycogen Storage Disease Type Ia (GSDIa).

The BLA is supported by 96-week data from the randomized, placebo-controlled phase 3 GlucoGene clinical trial (NCT05139316). Ultragenyx noted that the nonclinical and clinical modules of the BLA were submitted to the FDA in August 2025; it has now also completed submission of the chemistry, manufacturing, and controls (CMC) module of the BLA, thus finishing the BLA package.

Ultragenyx's Glycogen Storage Disease Gene Therapy DTX401 Continues to Enable Decreases in Reductions in Daily Cornstarch Intake at 96 Weeks

Ultragenyx has reported that in the phase 3 GlucoGene clinical trial (NCT05139316), patients treated with DTX401, an investigational adeno-associated virus serotype 8 (AAV8) vector-based gene therapy that is intended to treat glycogen storage disease type Ia, showed even greater reductions in daily cornstarch intake at 96 weeks post treatment compared with 48 weeks post treatment.

In comparison with previously reported 48-week data, the 96-week data showed that patients in both the ongoing DTX401 group and the group with crossover from placebo to DTX401 had greater reductions in their total daily cornstarch intake at their most recent visit compared with baseline. Specifically, the ongoing DTX401 group (n = 20) and crossover group (n = 19) together showed a 61% reduction from baseline at 96 weeks. Furthermore, patients in the DTX401 group achieved a 70% mean reduction in nighttime cornstarch intake and patients in the crossover group achieved a 75% mean reduction in nighttime cornstarch intake. Ultragenyx highlighted that across both these groups, 2 of 3 patients were able to completely eliminate 1 or more nighttime cornstarch doses in the posttreatment period.