Announcement • Jun 09
OS Therapies Achieves Global Regulatory Alignment on Design of Phase 3 Trial of OST-HER2 In Fully Resected Pulmonary Metastatic Osteosarcoma OS Therapies Inc. achieved alignment on the design of its pending Phase 3 study of OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary metastatic osteosarcoma with the U.S. Food & Drug Administration (FDA) and the U.K. Medicines and Healthcare products Regulatory Agency (MHRA). A confirmatory Phase 3 study is required to have commenced prior to the grant of a Biologics License Application (BLA) under the Accelerated Approval Program in the U.S. and Conditional Marketing Authorisation Applications (CMAAs) in the U.K., Europe and Australia. The Phase 3 study has received substantial support from international KOLs as part of regulatory meetings and is expected to commence late in the third quarter in Australia making the Company eligible for regulatory decisions in the fourth quarter. This alignment amongst each of the four key regulatory agencies where we are seeking early market access allows us to move forward with confidence as we prepare the Clinical Trial Notification (CTN) scheme submission to the Australian Therapeutic Goods Administration (TGA) to gain authorization to initiate the Phase 3 study. Australia has a very attractive R&D tax incentive program complementing the company's existing UK R&D tax credit strategy to incentivize the initiation of global clinical trials, allowing us to initiate the Phase 3 with minimal cost. MHRA and TGA are allowing us to initiate the Phase 3 trial with the same drug product used in the Phase 2b trial, positioning the Phase 3 trial to open in the third quarter of 2026. FDA, MHRA, EMA and TGA have now aligned with the Company on the CMC plan and potency assays for commercial drug product. These alignments allow the Company to be positioned for potential year-end regulatory decisions and 2027 patient access. Both FDA and MHRA also aligned with the EMA and TGA to include the pharmacodynamic biomarker signature as a surrogate clinical efficacy endpoint in the Phase 3. EMA has already begun rolling review of the regulatory dossier and we expect decisions regarding rolling review and Regenerative Medicine Advanced Therapy (RMAT) designation in the United States following our upcoming Type B Pre-BLA Meeting following the successful Type C Phase 3 Design Meeting last week. OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD) and Rare Pediatric Disease Designation (RPDD) from the FDA, and ODD, FTD and Advanced Therapeutic Medicinal Product (ATMP) designation from the EMA and MHRA. Under the RPDD program, if the Company is granted a BLA in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The Company has begun filing a BLA for osteosarcoma with FDA and has received rolling review from the EMA. OST-HER2, the Company's lead asset, is an immunotherapy leveraging the immune-stimulatory effects of Listeria bacteria to initiate a strong immune response targeting the HER2 protein. OST-HER2 is designed to target two mutated extracellular epitopes and one mutated intracellular epitope of the HER2 oncogene, requiring only one of these three epitopes to be present in a tumor (or micro-metastasis) to trigger the desired immune response. OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD) and Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and has received ODD, FTD and ATMP from the European Medicines Agency. The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma, demonstrating clinically significant benefit in the 12-month event free survival (EFS) primary endpoint of the study and the overall survival (OS) secondary endpoint. The Company is seeking a Biologics License Application (BLA) from the U.S. FDA for OST-HER2 in osteosarcoma in 2026 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. The Company also anticipates receiving Conditional Marketing Authorisation Applications from the U.K.'s Medicines and Healthcare products Regulatory Agency and the EMA for OST-HER2 in 2026. OST-HER2 has completed a Phase 1 clinical study primarily in breast cancer patients, in addition to showing preclinical efficacy data in various models of breast cancer. OST-HER2 has been conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma. Announcement • Jun 03
OS Therapies Achieves Statistically Significant 2.5-Year Overall Survival In Phase 2b Trial of OST-HER2 In Fully Resected Pulmonary Metastatic Osteosarcoma OS Therapies Inc. announced that its Phase 2b trial of OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary metastatic osteosarcoma achieved statistically significant benefit for OST-HER2 treated patients in overall survival at the 2.5-year timepoint (75% vs. 47%, p = 0.003). The topline data shows improving OST-HER2 survival benefit when compared with the 2-year data (2-year overall survival was 75% vs. 60%, p = 0.034). No new patient deaths were reported between the 2 and 2.5-year timepoints in the OST-HER2 treated group. OST-HER2 data is supported by a unique, patent pending pharmacodynamic immune response biomarker signature (Antigen Presentation, NK Cell Activation, T Cell Activation, etc.) that was developed as a surrogate clinical efficacy endpoint. OS Therapies is now updating its ongoing U.S. and international regulatory market authorization submissions for OST-HER2 in Metastatic Osteosarcoma with this new clinical efficacy data. The European Medicines Agency and the Australian Therapeutic Goods Administration have already aligned on the use of 3-year overall survival data that will be available in early Fourth Quarter 2026 as the key clinical efficacy data to support the Company's conditional Marketing Authorisation Applications, with rolling review already underway in Europe. The Company has an upcoming Type B Pre-BLA Meeting with the U.S. Food & Drug Administration to gain alignment on use of the forthcoming 3-year overall survival to support a Biologics Licensing Application under the Accelerated Approval Program. OS Therapies also has an upcoming Type C Meeting with FDA, and a separate Scientific Advice Meeting with the U.K.'s Medicines and Healthcare products Regulatory Agency, both being held in early June 2026, to confirm each agency's alignment with the key design parameters already agreed upon with EMA and TGA for the confirmatory Phase 3 protocol. OST-HER2 has received Orphan Drug Designation, Fast Track Designation and Rare Pediatric Disease Designation from the FDA, and Orphan Drug Designation, Fast Track Designation and ATMP from the EMA. Under the Rare Pediatric Disease Designation program, if the Company is granted a Biologics Licensing Application in the United States, it will become eligible to receive a Priority Review Voucher which it intends to sell. The Company has begun filing a Biologics Licensing Application for OST-HER2 in pulmonary metastatic osteosarcoma with FDA under the Accelerated Approval Program for OST-HER2 and has received rolling review from the EMA. The Company also anticipates Conditional Marketing Authorisation decisions in Europe, the U.K. and Australia in late 2026. The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma, demonstrating clinically significant benefit in the 12-month event free survival primary endpoint of the study and the overall survival secondary endpoint. The Company is seeking a Biologics License Application from the U.S. FDA for OST-HER2 in osteosarcoma in 2026 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. The Company also anticipates receiving Conditional Marketing Authorisations from the U.K.'s Medicines and Healthcare products Regulatory Agency and the EMA for OST-HER2 in 2026. OST-HER2 has completed a Phase 1 clinical study primarily in breast cancer patients, in addition to showing preclinical efficacy data in various models of breast cancer. OST-HER2 has been conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma. The Company also anticipates reading out data from a Phase 1b study of OST-504 in castration resistant prostate cancer in the first half of 2026. Announcement • May 16
OS Therapies Incorporated announced delayed 10-Q filing On 05/15/2026, OS Therapies Incorporated announced that they will be unable to file their next 10-Q by the deadline required by the SEC. 
