OS Therapies Announces Development of Two Novel Tunable Antibody Drug Conjugate (tADC)-Based Therapeutic Candidates

• First therapeutic candidate targets Breast Cancer, Lung Cancer and Gastric Cancer

• Second therapeutic candidate targets platinum-resistant Ovarian Cancer, Fallopian Tube Cancer and Primary Peritoneal Cancer

OS Therapies (NYSE American: OSTX) (“OS Therapies” or “the Company”), a clinical-stage immunotherapy and Antibody Drug Conjugate (ADC) biopharmaceutical company, today announced the development and in vitro concept data for two novel ADC therapeutic candidates leveraging the Company’s proprietary SiLinker™ technology. The Company has completed target engagement tests for both therapeutic candidates and confirmed their therapeutic potential. These new constructs will target Breast, Lung and Gastric Cancer; and Ovarian, Fallopian Tube and Primary Peritoneal Cancer, respectively.

The Company is advancing its tADC platform through successive product development de-risking milestones and intends to out-license certain therapeutic candidates and components that are strategic to potential partners’ pipelines – particularly the ph-sensitive SiLinker™. The Company’s first tADC asset OST-tADC-FRα-H has achieved proof of concept in animal models of ovarian cancer. With the additional two constructs now added to the pipeline, the Company is positioning itself to become a key provider of intellectual property for new therapeutic product development to partners. All while continuing to focus its internal resources on bringing to market the OST-HER2 off-the-shelf immunotherapy cancer vaccine platform for canines with osteosarcoma, and for humans with osteosarcoma and other HER2 positive cancers such as breast cancer and colorectal cancer.

About OS Therapies

OS Therapies is a clinical stage oncology company focused on the identification, development and commercialization of treatments for Osteosarcoma (OS) and other solid tumors. 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. The Company has completed enrollment for a 41-patient Phase 2b clinical trial of OST-HER2 in resected, recurrent osteosarcoma, with results expected in the fourth quarter of 2024. OST-HER2 has completed a Phase 1 clinical study primarily in breast cancer patients, in addition to showing strong preclinical efficacy data in various models of breast cancer. In addition, OS Therapies is advancing its next generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which features tunable, tailored antibody-linker-payload candidates. This platform leverages the Company’s proprietary silicone linker technology, enabling the delivery of multiple payloads. For more information, please visit www.ostherapies.com.

Forward-Looking Statements

Statements in this press release about future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute forward-looking statements within the meaning of the federal securities laws. These forward-looking statements and terms such as “anticipate,” “expect,” “intend,” “may,” “will,” “should” or other comparable terms involve risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. Those statements include statements regarding the intent, belief or current expectations of OS Therapies and members of its management, as well as the assumptions on which such statements are based. Prospective investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties, including those described under the section entitled “Risk Factors” of our Registration Statement on Form S-1 declared effective by the Securities and Exchange Commission (the “SEC”) on July 31, 2024, as well as any of our periodic reports filed with the SEC, and that actual results may differ materially from those indicated by such forward-looking statements. Any forward-looking statements contained in this press release speak only as of the date hereof, and, except as required by the federal securities laws, OS Therapies specifically disclaims any obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise.

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