OS Therapies Completes FDA Type C Statistical Methods Meeting and Provides Update on Global Regulatory Coordination for OST-HER2 Under Project Orbis

Recent U.K. MHRA Scientific Advice Meeting (SAM) that resulted in full alignment to initiate confirmatory Phase 3 trial in U.K. with existing Phase 2 drug product paved the way Conditional Marketing Authorisation Application (CMAA) submission in the coming weeks and Phase 3 trial initiation in mid Q4/'26 following Phase 2b drug product requalification MHRA's SAM participants' recommendation to Project Orbis U.K. leadership to take the global regulatory leadership mantle with U.S. FDA and EMA, coupled with granting the Company access to U.K. national patient registry, the UK Clinical Practice Research Datalink (CPRD) to strengthen comparator data while Phase 3 is ongoing to further improve interpretability of data during early market access phase Since 2021, 29 MHRA-led products have been approved by U.S. FDA via Project Orbis Company continues to engage with U.S. FDA on the non-Orbis Accelerated Approval route after successful Type C Statistical Methods Meeting that resulted in alignment on amended Phase 3 study design as buildout of OST-400 natural history database expands to include U.K. national patient registry data and Company awaits FDA decisions on RMAT, Rolling Review and CNPV ahead of the pending Q4/'26 completion of its ongoing BLA filing initiated in Q1/'26 BLAs granted via Project Orbis are eligible to receive Priority Review Vouchers (PRVs) and may also be granted via the Accelerated Approval Program Patient previously reported as lost to follow-up confirmed to be alive

OS Therapies, Inc. (NYSE American: OSTX) ("OS Therapies" or the "Company") , the world leader in gene-edited, Listeria-based cancer immunotherapies, today provided an update on global early market access regulatory coordination efforts being led by the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) following the Company's acceptance of MHRA's request to become the lead regulatory agency to drive early market access for OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary metastatic osteosarcoma (the "Metastatic Osteosarcoma Program") under Project Orbis. Project Orbis is the U.S. Food & Drug Administration (FDA) Oncology Center of Excellence (OCE) initiative started in May 2019 to provide a framework for concurrent submission and review of oncology products among international partners. Since 2021, 29 MHRA-led oncology products have been approved by the FDA under Project Orbis.

FDA has aligned with the Company on the proposed adaptive design of the pending Phase 3 study, paving the way for the U.K. portion of the global study to begin with the requalified materia...