OS Therapies Gains EMA, MHRA, TGA Alignment for OST-HER2 Phase 3 Launch
OSTX•OS Therapies has achieved full alignment with EMA, MHRA and TGA on OST-HER2 Conditional Marketing Authorisation applications, hinging on Fall 2026 3-year overall survival data and pediatric plans. The Phase 3 trial is slated to start in late Q3 2026 in Australia, expanding to Europe, the U.K. and U.S. thereafter.
1. Regulatory Alignment on OST-HER2 Program
OS Therapies has secured full alignment with EMA, MHRA and TGA on all non-clinical, CMC, clinical safety and confirmatory Phase 3 protocol design elements for OST-HER2. The company earned ATMP designation in the EU and U.K., received positive EMA PDCO feedback, and holds a September 30, 2026 submission window for Conditional Marketing Authorisation Applications while finalizing Pediatric Investigation Plans.
2. Phase 3 Trial Initiation and Scope
The confirmatory Phase 3 study for pulmonary metastatic osteosarcoma is set to commence in Australia at the end of Q3 2026 using the existing Phase 2 drug product batch. Following early access decisions, the trial will expand into the U.K., continental Europe and the United States under aligned protocols and comparator frameworks.
3. FDA Engagement and BLA Pathway
OS Therapies submitted non-clinical and clinical BLA modules to the FDA in January 2026 and achieved alignment on Phase 3 design during a Type C meeting. A Type B Statistical Methods meeting is scheduled to set parameters for 3-year overall survival analysis, paving the way for a Pre-BLA review in early Fall 2026; the company’s CNPV letter of intent has been accepted.
4. OS Animal Health Canine Study Results
The company’s OS Animal Health subsidiary published peer-reviewed data showing OST-HER2 plus radiation significantly improved survival in frontline canine osteosarcoma compared with radiation alone, underscoring expanded therapeutic potential and bolstering its animal health pipeline.
