OS Therapies Inc. provided a global regulatory update on OST-HER2 for preventing or delaying recurrent, fully resected pulmonary metastatic osteosarcoma.

OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, today provided a global regulatory update for OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma (the "Human Metastatic Osteosarcoma Program").

Following the submission of the Non-Clinical and Chemistry, Manufacturing & Controls (CMC) modules of its Biologics License Application (BLA) to U.S. Food & Drug Administration (FDA) at the end of January 2026, the Company anticipates releasing additional biomarker data from its Human Metastatic Osteosarcoma Program in the first quarter of 2026. These analyses are intended to further characterize immune pathway activation and evaluate the relationship between biomarker expression and observed clinical outcomes.

The Company expects to complete conditional Marketing Authorisation Application (MAA) submissions to both the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA) by the end of the first quarter of 2026. The Company remains on track to submit the Clinical BLA module to the FDA following an anticipated Type D meeting expected to occur in March 2026.

"We continue to advance our global regulatory strategy following previously reported pre-specified biomarker analyses demonstrating concordant immune pathway activation signatures and clinical outcomes in both human and canine elite responders (long term survivors) when compared with patients who showed no clinical benefit," said Paul Romness, MPH, CEO of OS Therapies. "We have now nearly completed additional follow-on biomarker analyses designed to further elucidate the drug's treatment effect and its relationship to clinical outcomes. We are hopeful the data will provide further support for the use of these biomarkers as surrogate endpoints of clinical efficacy. We expect to share this data in the coming weeks."

Concurrent with this announcement, the Company disclosed that it is assembling a meeting of U.S., U.K. and European osteosarcoma key opinion leaders to review the clinical and biomarker data from the Human Metastatic Osteosarcoma Program and provide input on proposed confirmatory trial designs for the Company's confirmatory clinical development program. The Company is seeking a BLA under the Accelerated Approval Program ('Accelerated Approval') in the U.S. and conditional MAAs in the U.K. and Europe, which all require confirmatory studies to be initiated prior to approval. The Company anticipates initiating the confirmatory trial in the third quarter of 2026 with the opening of a single site that allows it to meet the Accelerated Approval statutory requirement, with broader site activation expected following regulatory approval.

OST-HER2 has received FDA Orphan Drug Designation (ODD) and Fast Track Designation from the FDA & EMA and has received Rare Pediatric Disease Designation (RPDD) from the FDA. Under the RPDD program, if the Company receives Accelerated Approval in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The most recent publicly disclosed PRV transaction occurred in January 2026 at a reported value of $200 million.

Additionally, the Company announced that it has been informed that Ayala Pharmaceuticals, Inc. ('Ayala') has informed its shareholders that Ayala is dissolving. The Company acquired all listeria-based clinical, pre-clinical and intellectual property assets from Ayala in April 2025, issuing to Ayala the equivalent of 4.8 million shares of OS Therapies common stock that became eligible for trading on October 9, 2025. The Company was informed by Ayala representatives that Ayala completed the liquidation of its OS Therapies common stock on February 9, 2026, and no longer holds any securities in the Company.

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