---
schema_version: "secwatch.filing_event.v1"
accession: "0001213900-26-050211"
form_type: "8-K"
ticker: "OSTX"
cik: "0001795091"
company_name: "OS Therapies Inc"
filed_at: "2026-04-30T23:59:59+00:00"
generated_at: "2026-05-15T01:03:37.644565+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# EMA rolling review for OST-HER2; ATGA aligns on 3-year OS endpoint; peak EU sales >$300M

## Summary
- EMA initiated rolling review of OST-HER2 CMA for preventing recurrence in resected pulmonary metastatic osteosarcoma.
- EMA and Australia TGA agreed 3-year overall survival as approvable endpoint; seroconversion data supports CMA.
- UK MHRA granted Advanced Therapy Medicinal Product (ATMP) designation to OST-HER2.
- Company forecasts peak European osteosarcoma sales exceeding $300M, with over $50M expected in 2027.
- Confirmatory Phase 3 trial initiation planned for Q3 2026 in Australia; FDA and MHRA meetings in Q2 2026.

## SEC filing metadata
- accession: 0001213900-26-050211
- form_type: 8-K
- ticker: OSTX
- cik: 0001795091
- company_name: OS Therapies Inc
- filed_at: 2026-04-30T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1795091/000121390026050211/0001213900-26-050211-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1795091/000121390026050211/ea0288588-8k_ostherapies.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001213900-26-050211
- JSON: https://secwatch.observer/filing/0001213900-26-050211.json
- Plain text: https://secwatch.observer/filing/0001213900-26-050211.txt

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