---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-24-113085"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2024-10-07T23:59:59+00:00"
generated_at: "2026-05-30T19:12:22.399578+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx gets FDA Breakthrough Therapy Designation for setrusumab in osteogenesis imperfecta

## Summary
- Received FDA Breakthrough Therapy Designation for setrusumab (UX143) for OI Type I, III, IV in patients ≥2 years.
- Designation based on Phase 2 data from Orbit (14-month) and Asteroid studies showing significant fracture rate reduction.
- Breakthrough Therapy aims to expedite development and review for serious diseases with preliminary clinical evidence.
- Ultragenyx collaborates with Mereo BioPharma on UX143 development.
- Designation does not guarantee approval but may speed regulatory process.

## SEC filing metadata
- accession: 0000950170-24-113085
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2024-10-07T23:59:59+00:00
- event_type: regulatory
- 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/1515673/000095017024113085/0000950170-24-113085-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000095017024113085/rare-20241007.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-24-113085
- JSON: https://secwatch.observer/filing/0000950170-24-113085.json
- Plain text: https://secwatch.observer/filing/0000950170-24-113085.txt

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