secwatch.observer — SEC 8-K summary
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Issuer:     Ultragenyx Pharmaceutical Inc. (RARE)
CIK:        0001515673
Form:       8-K
Filed at:   2026-03-12T23:59:59+00:00
Accession:  0001193125-26-103167
Event type: other_material
Sentiment:  positive
Materiality: 0.85
Item codes: 8.01
LLM model:  deepseek-v4-flash:cloud@v2

Ultragenyx DTX301 Phase 3 meets primary endpoint: 18% ammonia AUC reduction (p=0.018) in OTC deficiency
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- DTX301-treated patients (n=18) showed 18% reduction in 24-hour plasma ammonia AUC vs placebo (n=19) at Week 36 (p=0.018).
- 8 of 9 patients with abnormal baseline ammonia reached normal levels; treated patients maintained normal ammonia despite 27% mean reduction in scavenger meds.
- 71% of treated patients reported much improvement on PGIC vs 0% for placebo at Week 24.
- One SAE of acute hepatitis (resolved with steroids); 5 hyperammonemic crises in placebo (1 death) vs 1 in treated (no deaths).
- Study continues to second primary endpoint on treatment burden; data expected H1 2027.

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1515673/000119312526103167/0001193125-26-103167-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1515673/000119312526103167/rare-20260312.htm
  HTML page:      https://secwatch.observer/filing/0001193125-26-103167

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