---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-332422"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2025-12-29T23:59:59+00:00"
generated_at: "2026-05-16T12:06:06.117915+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx's setrusumab fails Phase 3 primary endpoints in OI; expense cuts planned

## Summary
- Orbit and Cosmic studies did not meet primary endpoint of reducing annualized clinical fracture rate versus comparators.
- Both studies achieved secondary endpoint of significant improvement in bone mineral density (BMD).
- Company plans to implement significant expense reductions; evaluating next steps for the program.
- Safety profile unchanged; no new safety signals observed.

## SEC filing metadata
- accession: 0001193125-25-332422
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2025-12-29T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1515673/000119312525332422/0001193125-25-332422-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000119312525332422/rare-20251229.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-332422
- JSON: https://secwatch.observer/filing/0001193125-25-332422.json
- Plain text: https://secwatch.observer/filing/0001193125-25-332422.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.