• Meeting to occur in mid-September 2026
  • Interim 3-year Overall Survival data expected early September, 2026
  • Decisions on appropriate comparator arm to interpret OST-HER2 clinical efficacy, RMAT designation and Rolling Review expected following this meeting
  • Sustained overall survival benefit observed between 2-year and 2.5-year timepoints
  • U.K. MHRA Statistical Methods Scientific Advice Meeting granted in parallel

New York, New York and Rockville, Maryland--(Newsfile Corp. - August 13, 2026) - OS Therapies, Inc. (NYSE:OSTX) ("OS Therapies" or "the Company"), the world leader in gene-edited, Listeria-based cancer immunotherapies, today announced that the U.S. Food and Drug Administration (FDA) has granted the Company's requested Type C Statistical Methods meeting to review the 2.5 year overall survival data from the Phase 2b trial of OST-HER2 in the prevention of recurrence in fully resected, pulmonary metastatic osteosarcoma (the "Metastatic Osteosarcoma Trial"). The Company expects the FDA Type C Statistical Methods Meeting to occur in mid-September 2026 with members from division within the Center for Biologics Evaluation and Research (CBER), in parallel with the pending Biomarker Data Review Meeting being scheduled with members of the Center for Drug Evaluation and Research's (CDER) Biomarker Qualification Program (BQP). CBER is ultimately responsible for granting regulatory approval for gene-edited products such as OST-HER2. The Company expects to announce interim 3-year overall survival data in early September 2026.

Concurrent with this announcement, the U.K. Medicines and Healthcare products Regulatory Agency (MHRA) has granted a new Scientific Advice Meeting (SAM) to review the statistical methods that will be used to support the Company's pending Conditional Marketing Authorisation Application (CMAA) submission, including whether the Company can finalize its U.K. CMAA submission leveraging 2.5-year overall survival. This meeting is expected to occur in September 2026.