OS Therapies Requests FDA Type B Meeting To Review Its 2.5-Year OST-HER2 Overall Survival Data And To Confirm Alignment That 3-year Overall

OS Therapies, Inc. (NYSE: OSTX ) ("OS Therapies" or "the Company"), the world leader in gene-edited, Listeria-based cancer immunotherapies, today provided regulatory update on the Company's interactions with the U.S.

Food and Drug Administration (FDA) in its pursuit of a Biologics License Application (BLA) under the Accelerated Approval Program (Accelerated Approval) for OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary metastatic osteosarcoma (the "Metastatic Osteosarcoma Program").

OS Therapies has requested a Type B Meeting to review the Company's 2.5-year overall survival data and to confirm alignment that 3-year overall survival data is an approvable clinical efficacy endpoint.

The Company recently aligned with the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency on 3-year overall survival as the proposed approvable clinical endpoint to support Conditional Marketing Authorisations.

The Company has also submitted its pharmacodynamic response biomarker data to the FDA's Biomarkers, Endpoints, and other Tools (BEST) program for evaluation as a surrogate clinical efficacy data.

FDA and EMA have begun joint coordination on the OST-HER2 regulatory dossier to evaluate early market access.

OS Therapies intends to review with FDA the potential inclusion of concurrent natural history control database OST-400, "Recurrent Osteosarcoma after Resection in Children and Young Adults: A Retrospective Longitudinal Study," as an added synthetic control comparator arm at the meeting.

The Company recently made significant progress with recruitment for OST-400 that now allows the Company to respond to June 2025 Breakthrough Therapy Designation (BTD) request feedback and September 2025 End of Phase 2 Meeting guidance provided by FDA on OST-400's development.

OS Therapies also expects to review outstanding Rolling Review, Regenerative Medicine Advanced Therapy (RMAT) designation and BTD requests with FDA at the meeting.

The potential suitability of OST-400 as a second supportive comparator arm for Accelerated Approval is in addition to the suitability of pooled historical control data already shared with FDA to support Accelerated Approval.