---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-25-094921"
form_type: "8-K"
ticker: "MREO"
cik: "0001719714"
company_name: "Mereo BioPharma Group plc"
filed_at: "2025-07-10T23:59:59+00:00"
generated_at: "2026-05-18T08:46:43.996921+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.7
calibrated_materiality_score: 0.7
confidence: "high"
source: SEC EDGAR
---

# Mereo BioPharma and Ultragenyx Provide Update on Phase 3 Orbit and Cosmic Studies of UX143 in Osteogenesis Imperfecta

## Summary
- The Phase 3 Orbit study final analysis is expected around end of 2025, with a threshold of p<0.04.
- DMC informed Ultragenyx that UX143 has an acceptable safety profile and study should continue to final analysis.
- Safety in the younger patient population (Cosmic study) is consistent with other studies; no interim analysis of Cosmic data.
- Final analyses will occur after patients have been on therapy for at least 18 months; threshold for Cosmic is p<0.05.

## SEC filing metadata
- accession: 0000950170-25-094921
- form_type: 8-K
- ticker: MREO
- cik: 0001719714
- company_name: Mereo BioPharma Group plc
- filed_at: 2025-07-10T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.7
- calibrated_materiality_score: 0.7
- confidence: high
- sec_items: 8.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1719714/000095017025094921/0000950170-25-094921-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1719714/000095017025094921/mreo-20250709.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-25-094921
- JSON: https://secwatch.observer/filing/0000950170-25-094921.json
- Plain text: https://secwatch.observer/filing/0000950170-25-094921.txt

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