---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-25-090616"
form_type: "8-K"
ticker: "RARE"
cik: "0001515673"
company_name: "Ultragenyx Pharmaceutical Inc."
filed_at: "2025-06-27T23:59:59+00:00"
generated_at: "2026-05-18T15:48:48.759253+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Ultragenyx receives FDA Breakthrough Therapy Designation for GTX-102 in Angelman syndrome

## Summary
- FDA granted Breakthrough Therapy Designation for GTX-102 (apazunersen) for Angelman syndrome.
- Based on Phase 1/2 study in 74 patients (4-17 years) with full maternal UBE3A deletion showing consistent developmental gains.
- Designation aims to expedite development and review; may enable rolling submission and enhanced FDA guidance.
- Positive data shows rapid, sustained improvements across multiple symptom domains over up to three years.

## SEC filing metadata
- accession: 0000950170-25-090616
- form_type: 8-K
- ticker: RARE
- cik: 0001515673
- company_name: Ultragenyx Pharmaceutical Inc.
- filed_at: 2025-06-27T23:59:59+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/1515673/000095017025090616/0000950170-25-090616-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1515673/000095017025090616/rare-20250627.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-25-090616
- JSON: https://secwatch.observer/filing/0000950170-25-090616.json
- Plain text: https://secwatch.observer/filing/0000950170-25-090616.txt

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