---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-24-112402"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2024-10-03T23:59:59+00:00"
generated_at: "2026-05-30T21:26:43.937026+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# UX701 gene therapy shows clinical activity; 6 of 15 Wilson disease patients tapered off standard-of-care

## Summary
- 15 patients enrolled across 3 dose cohorts; 6 completely tapered off chelators/zinc therapy; 1 additional began tapering.
- Non-ceruloplasmin bound copper stabilized to normal levels; ceruloplasmin-copper activity increased, indicating improved ATP7b function.
- UX701 well tolerated with no unexpected treatment-emergent adverse events or significant immunologic safety events.
- Company plans to enroll a fourth cohort at moderately increased dose with optimized immunomodulation regimen to enhance efficacy.
- Dose selection for randomized placebo-controlled Stage 2 and long-term follow-up in Stage 3 are planned.

## SEC filing metadata
- accession: 0000950170-24-112402
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2024-10-03T23:59:59+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/1515673/000095017024112402/0000950170-24-112402-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000095017024112402/rare-20241003.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-24-112402
- JSON: https://secwatch.observer/filing/0000950170-24-112402.json
- Plain text: https://secwatch.observer/filing/0000950170-24-112402.txt

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