• OST-HER2 remains eligible for Priority Review Voucher ("PRV") if approved by the U.S. Food and Drug Administration's ("FDA") on or before September 30, 2029
• Company continues to benefit from its UK research and development program, through which it received approximately $900,000 in non-dilutive tax credits

Grasonville, Maryland--(Newsfile Corp. - November 13, 2026) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or the "Company"), the world leader in gene-edited, Listeria-based cancer immunotherapies, today announced that the FDA's shelving of the Commissioner's National Priority Voucher ("CNPV") has no impact on the Company's rare pediatric disease PRV prospects. The shelving does not affect the FDA's rare pediatric disease PRV program, a statutory program currently authorized through September 30, 2029, under which vouchers are transferable. OST-HER2 may qualify for a PRV if it is approved by the FDA on or before September 30, 2029.

"This action by the FDA does not affect OST-HER2's potential eligibility for a PRV, which, if received, could be an important source of non-dilutive capital to support the further development of our drug platform and new therapies to treat critical unmet needs," said Frank Knuettel II, OS Therapies' Chief Financial Officer. Mr. Knuettel continued "Receiving a PRV will represent a major value driver for our shareholders. When monetized, it will fund our ongoing R&D without equity dilution providing us with tremendous financial and strategic flexibility."

Additionally, OS Therapies continues to benefit from its UK research and development program and announces that it has received approximately $900,000 in the latest tax credit from the HM Revenue and Customers department of the UK government.

About OS Therapies
OS Therapies is a clinical stage oncology company focused on the identification, development, and commercialization of treatments for Osteosarcoma and other solid tumors. The Company is the world leader in gene-edited, Listeria-based cancer immunotherapies. 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 FDA and has received ODD, and Advanced Therapy Medicinal Products (ATMP) from the European Medicines Agency.

The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary 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 intends to complete a Biologics License Application (BLA) submission to the U.S. FDA for OST-HER2 in osteosarcoma in the fourth quarter of 2026 and, if approved, would become eligible to receive a PRV that it could then sell. The Company also anticipates requesting Conditional Marketing Authorisation Applications (CMAAs) from the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA)for OST-HER2 in the fourth quarter of 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 was previously conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma. The Company has also completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer.

In addition, OS Therapies is advancing its next-generation Antibody Drug Conjugate (ADC) and Drug Conjugates (DC), known as tunable ADC (tADC), which features tunable, tailored antibody-linker-payload candidates. This platform leverages the Company's proprietary silicon Si-Linker and Conditionally Active Payload (CAP) technology, enabling the delivery of multiple payloads per linker. For more information, please visit www.ostherapies.com.

Forward-Looking Statements

This press release contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are subject to the safe harbor created by the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, without limitation, statements regarding the timing of the Company's planned BLA submission and applications for conditional marketing authorization; the clinical development, regulatory review and potential approval and commercialization of OST-HER2; and the Company's potential eligibility for, receipt of, and ability to sell a PRV. Words such as "anticipate," "believe," "could," "expect," "intend," "may," "plan," "potential," "should," "will" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these words. These statements are based on the current expectations and assumptions of OS Therapies and its management and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such forward-looking statements. Such risks and uncertainties include, but are not limited to: changes in U.K. tax law or HMRC practice; fluctuations in foreign currency exchange rates; chemistry, manufacturing and controls (CMC) matters relating to OST-HER2; OST-HER2 product stability; the timing and outcome of regulatory submissions and the potential approval of OST-HER2 by the FDA and applicable foreign regulatory authorities; changes in, or the suspension, expiration or termination of, FDA priority review voucher programs, and the market value of any priority review voucher; the Company's funding runway and need for substantial additional capital; and the other risks and uncertainties described under the heading "Risk Factors" in the Company's most recent Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q and other filings with the Securities and Exchange Commission. The forward-looking statements contained in this press release speak only as of the date of this press release, and OS Therapies undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

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To view the source version of this press release, please visit https://www.newsfilecorp.com/release/323890