$OSTXJun 2, 2026, 11:08 AMAI processed
OSTX: OST-HER2 shows statistically significant 2.5‐yr OS benefit (75% vs 47%) in Phase 2b metastatic osteosarcoma
AI Summary
OS Therapies (OSTX) reported Phase 2b data showing OST-HER2 achieved a 2.5‐year overall survival of 75% vs a 47% pooled historical control (p=0.003) in fully resected pulmonary metastatic osteosarcoma, with no new patient deaths between years 2 and 2.5. The company is adding the data to regulatory dossiers, has EMA/TGA alignment that 3‐year OS (due early Q4‐2026) will be the key approvable endpoint, has upcoming FDA/MHRA meetings to seek alignment, and expects to start a confirmatory Phase 3 in late Q3‐2026 while pursuing accelerated/conditional authorizations in late 2026.
Positives
- Statistically significant 2.5‑year overall survival: 75% (OST-HER2) vs 47% (pooled historical control), p=0.003
- No new deaths in OST-HER2 group between 2.0 and 2.5 years, suggesting durability of the observed benefit
- EMA and Australian TGA aligned on 3‑year OS as key approvable endpoint; rolling review in Europe and scheduled meetings with FDA/MHRA
Negatives
- Comparison is to a pooled historical control rather than a randomized concurrent control
- Regulators require a confirmatory Phase 3 (must begin prior to any early market access), so approvals depend on future trial initiation and outcomes
- Timelines and approval expectations are forward‑looking and contingent on future data and regulatory alignment; company noted cash/runway risk into 2027