Ultragenyx has finalized its rolling Biologics License Application submission to the U.S. Food and Drug Administration for DTX401, an AAV8 gene therapy targeting Glycogen Storage Disease Type Ia. The application, built on data from 52 treated patients with up to six years of follow-up, includes nonclinical, clinical and, as of December 30, the chemistry, manufacturing and controls modules. Phase 3 GlucoGene study results showed significant reductions in both quantity and frequency of daily cornstarch intake, maintenance of low hypoglycemia levels, improved euglycemia and fasting tolerance, and meaningful gains on the Patient Global Impression of Change scale. DTX401 holds Rare Pediatric Disease, orphan drug, Fast Track and regenerative medicine advanced therapy designations from the FDA, as well as orphan drug and PRIME designations from the European Medicines Agency.

Shares of Ultragenyx surged by approximately 15.5% on unusually heavy volume, with roughly 11 million shares trading versus an average daily turnover of 1.7 million. The move reflected investor optimism over the DTX401 submission and its potential to become the first approved therapy addressing the underlying cause of GSDIa. Market capitalization stands near $1.9 billion, and while the jump signals bullish sentiment, recent trends in earnings estimate revisions have shown downward adjustments, suggesting that some analysts remain cautious about short-term momentum.

Ultragenyx’s partnered Phase 3 Orbit and Cosmic studies of setrusumab for osteogenesis imperfecta failed to meet primary endpoints but did achieve secondary endpoints, including statistically significant improvements in bone mineral density. Wells Fargo analyst Benjamin Burnett maintained an overweight rating, lowering his price target to $45 from $65—implying upside of over 128% from yesterday’s closing level—citing a favorable risk-reward profile ahead of FDA feedback on the therapy. Burnett noted that while net losses persist and revenue is driven by a small portfolio of marketed products, the potential approval of DTX401 and positive secondary data for setrusumab justify continued investor interest.