---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-24-072119"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2024-06-12T23:59:59+00:00"
generated_at: "2026-06-01T04:49:34.926531+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx and Mereo report setrusumab cuts fracture rate 67% and boosts BMD 22% in OI Phase 2

## Summary
- Median annualized fracture rate reduced 67% from 0.72 to 0.00 (p=0.0014) over mean 16 months in 24 patients.
- Lumbar spine BMD increased 22% from baseline at month 12 (p<0.0001); Z-score normalized from -1.73 to -0.49.
- No treatment-related serious adverse events or hypersensitivity reactions; most common AEs: infusion-related events, headache.
- Phase 3 portion of Orbit study enrolled 158 patients; Cosmic study enrolled 69 patients; 14-month data to be presented at future meeting.

## SEC filing metadata
- accession: 0000950170-24-072119
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2024-06-12T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1515673/000095017024072119/0000950170-24-072119-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000095017024072119/rare-20240611.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-24-072119
- JSON: https://secwatch.observer/filing/0000950170-24-072119.json
- Plain text: https://secwatch.observer/filing/0000950170-24-072119.txt

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