secwatch.observer — SEC 8-K summary
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Issuer:     Ultragenyx Pharmaceutical Inc. (RARE)
CIK:        0001515673
Form:       8-K
Filed at:   2025-09-08T23:59:59+00:00
Accession:  0000950170-25-113553
Event type: other_material
Sentiment:  positive
Materiality: 0.80
Item codes: 8.01
LLM model:  deepseek-v4-flash:cloud@v2

Ultragenyx reports positive longer-term Phase 3 data for DTX401 gene therapy in GSDIa
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- DTX401 met primary endpoint at Week 48: mean cornstarch reduction 41% vs 10% placebo (p<0.0001).
- At Week 96, DTX401 and crossover groups each achieved mean 61% reduction in daily cornstarch from baseline.
- Two-thirds of participants eliminated at least one nighttime cornstarch dose; fasting tolerance improved through Year 2.
- 83% of DTX401 group and 95% of crossover reported improved disease burden at Week 96 per PGIC.
- Open-label cohort (n=3) achieved 95% mean cornstarch reduction at Week 24; all discontinued cornstarch by Week 36.

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1515673/000095017025113553/0000950170-25-113553-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1515673/000095017025113553/rare-20250908.htm
  HTML page:      https://secwatch.observer/filing/0000950170-25-113553

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer