---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-130498"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2026-03-30T23:59:59+00:00"
generated_at: "2026-05-15T08:22:08.251207+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.55
calibrated_materiality_score: 0.55
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx receives FDA IND clearance for UX016 in GNE myopathy; Phase 1/2 to start H2 2026

## Summary
- FDA cleared IND for UX016, a prodrug of sialic acid for GNE myopathy, a rare inherited neuromuscular disorder.
- UX016 is a small molecule prodrug designed to enhance sialic acid delivery to muscle cells.
- Phase 1/2 study planned for H2 2026, enrolling ~24 adults aged 18–55 in the US; externally funded by a patient group.
- Study will evaluate safety, pharmacokinetics, and efficacy including muscle strength and functional measures through 48 weeks.

## SEC filing metadata
- accession: 0001193125-26-130498
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2026-03-30T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.55
- calibrated_materiality_score: 0.55
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1515673/000119312526130498/0001193125-26-130498-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000119312526130498/rare-20260330.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-130498
- JSON: https://secwatch.observer/filing/0001193125-26-130498.json
- Plain text: https://secwatch.observer/filing/0001193125-26-130498.txt

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