OS Therapies Appoints Craig Eagle, MD as Strategic Advisor

• Senior leadership roles at Guardant Health, Genentech and Pfizer
• Regulatory, clinical and commercial expertise in therapeutics and biomarkers
• Will assist with osteosarcoma regulatory advice and oncology pipeline prioritization

New York, New York--(Newsfile Corp. - April 8, 2026) - OS Therapies, Inc. (NYSE:OSTX) ("OS Therapies" or "the Company"), the world leader in gene-edited, listeria-based cancer immunotherapies, today announced that Craig Eagle, MD, was appointed to the Company's newly-formed strategic advisory board. The Company's strategic advisory board is being formed to assist the Company in fine-tuning its osteosarcoma regulatory execution plan and to help develop a detailed pipeline development plan to prioritize the highest value opportunities beyond osteosarcoma. The Company currently has clinical-stage pipeline assets in breast cancer, colorectal cancer, non-small cell lung cancer, prostate cancer, HPV-related cancers, as well as several other oncology indications.

"I am excited to help advise OS Therapies at this crucial time in the Company's life cycle," said Craig Eagle, MD, inaugural member of the Company's strategic advisory board. "I have been following the listeria-based immuno-oncology field for well over a decade. With OS Therapies' focus on an ultra-rare pediatric cancer where other immunotherapy assets have faced significant challenges, they are showing the value of this more comprehensive listeria-based immunostimulatory approach. Having been privy to the biomarker data from the Phase 2b trial, I am confident in the direction the Company is going and its prospects in osteosarcoma and beyond."

Dr. Craig Eagle currently serves as Guardant Health's Chief Medical Officer. Prior to joining Guardant Health, Dr. Eagle served as Vice President of Medical Affairs Oncology for Genentech, where he oversaw the medical programs across the oncology portfolio and developed innovative cancer trials and strategies in personalized health care. Prior to Genentech, Dr. Eagle held several leadership roles at Pfizer, including oncology business lead for the United Kingdom and Canada, global lead for Oncology Strategic Alliances and Partnerships, and global head of the Oncology Therapeutic Area Global Medical and Outcomes Group, where he oversaw the U.S. oncology business, an extensive clinical trial program, health outcomes assessments, and scientific collaborations. Dr. Eagle attended medical school at the University of New South Wales in Sydney, Australia and received his general internist training at Royal North Shore Hospital in Sydney. Dr. Eagle completed his specialist training in hemato-oncology and laboratory hematology at Royal Prince Alfred Hospital in Sydney and was granted a Fellowship in the Royal Australasian College of Physicians (FRACP) and the Royal College of Pathologists Australasia (FRCPA).

"Given Dr. Eagle's expertise in oncology therapeutic and biomarker development, we are very pleased to be able to leverage his experience as we engage with global regulators on the utility of our biomarker data to drive the regulatory process forward, as well as thinking through prioritization of our pipeline to create maximum shareholder value once the Company is commercial," said Paul Romness, MPH, Chair & CEO of OS Therapies.

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. The Company is the world leader in 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 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD) and Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and has received ODD, FTD and ATMP from the European Medicines Agency. The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma, demonstrating statistically significant benefit in the 12-month event free survival (EFS) primary endpoint of the study and the overall survival (OS) secondary endpoint. The Company anticipates receiving a Biologics License Application (BLA) from the U.S. FDA for OST-HER2 in osteosarcoma in 2026 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. The Company also anticipates receiving Conditional Marketing Authorisations from the U.K.'s Medicines and Healthcare products Regulatory Agency and the EMA for OST-HER2 in 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 has been conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma. The Company also anticipates reading out data from a Phase 1b study of OST-504 in castration resistant prostate cancer in the first half of 2026.

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 silicone 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

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. OS Therapies cautions readers that forward-looking statements are based on management's expectations and assumptions as of the date of this press release and are subject to certain risks and uncertainties that could cause actual results to differ materially, including, but not limited to our expected to provide cash runway into 2027, the intended use of net proceeds from the offering, the potential approval of OST-HER2 by the U.S. FDA and other risks and uncertainties described in "Risk Factors" in the Company's most recent Annual Report on Form 10-K and other subsequent documents the Company files with the Securities and Exchange Commission. 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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To view the source version of this press release, please visit https://www.newsfilecorp.com/release/291627