• OS Animal Health (OSAH), a wholly-owned subsidiary of OS Therapies (OSTX), targeting Initial Public Offering (IPO) on NYSE American or Nasdaq Capital Markets national stock exchange in the first half of 2026 (1H/2026)
• OSTX shareholders expected to receive one (1) share of OSAH for every ten (10) shares of OSTX owned as of the expected to-be-determined 1H/2026 record date
• OSAH to focus primarily on the re-establishment of USDA conditional approval and commercialization of immunotherapy OST-HER2 for canine osteosarcoma and other HER2 positive cancers in animals
• OST-HER2 featured in 2025 2x Emmy-nominated and Anthem Award-winning documentary 'Shelter Me: Cancer Pioneers' streaming on PBS
• OSTX reiterates release date of January 15, 2026 for biomarker data from Phase 2b OST-HER2 trial in human pulmonary metastatic osteosarcoma that will be used to support upcoming Biologics License Application submission with US FDA

New York, New York--(Newsfile Corp. - January 14, 2026) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, today announced that its wholly-owned subsidiary OS Animal Health Corp (OSAH) has filed a Form S-1 with the Securities Exchange Commission (SEC) in preparation for an Initial Public Offering (IPO). OSAH intends to list on either the NYSE American or Nasdaq Capital Markets national stock exchange in the first half of 2026 (1H/2026). OS Therapies shareholders are expected to receive one (1) share of OSAH for every ten (10) shares of OS Therapies owned as of the to-be-determined 1H/2026 record date.

provided evidence of key similarities in the molecular makeup and clinical behavior of human and canine osteosarcoma. Many of the genes that are upregulated in canine patients with better clinical outcomes are indicative of interactions between tumors and immune cells, suggesting that patients with osteosarcoma fare better when their immune systems mount a robust anti-tumor response. The knowledge gained from the study is helping researchers explain why many patients lack a strong immune response to osteosarcoma, and how that response might be improved. Data from an OST-HER2 showed upregulation of specific immune activation biomarkers that predicted clinical outcomes. in a subset of OST-HER2-treated patients, with an additional manuscript describing the clinical and immune biomarker data having recently been submitted for peer-review publication.

"As parent company OS Therapies diligently pursues a Biologics Licensing Application (BLA) under the Accelerated Approval Program (Accelerated Approval) for OST-HER2 in human osteosarcoma, we have been relying heavily on data generated from naturally occurring osteosarcoma in domestic canines to generate key immune biomarker signature hypotheses that we are using to pre-specify treatment outcomes biomarkers in our human OST-HER2 metastatic osteosarcoma program," said Paul Romness, MPH, Chairman & CEO of OS Therapies and Interim-CEO of OS Animal Health. "Two (2) separate research studies in different disease settings of canine osteosarcoma have shown improved patient outcomes in response to OST-HER2 treatment, with specific immune biomarkers being associated with antitumor immunity and improved clinical outcomes. There is a significant market opportunity for a novel treatment such as OST-HER2 that has demonstrated strong immune activation and treatment outcomes in canine osteosarcoma."

OSAH intends to focus primarily on the re-establishment of United States Department of Agriculture (USDA) conditional approval and commercialization of OST-HER2 for osteosarcoma in canines, as well as the treatment of HER2-positive cancers in animals. according to Towards Health, driven primarily by the North American market due to its advanced veterinary infrastructure and high expenditure on pet healthcare. , the canine cancer segment held the largest revenue share of over 86.09% in 2024 and is also expected to grow at the highest growth rate of 12.56% during 2025-2030. This growth is due to the rising prevalence of cancer and growing awareness of treatment options. In addition, the increasing pet dog population also contributes to the segment's growth.

"Canine osteosarcoma remains one of the most deadly forms of cancer in dogs," said Edward Robb, DVM, Chief Veterinary Officer (CVO) of OS Animal Health. "OST-HER2 has demonstrated potential to significantly improve patient outcomes in multiple research studies of canine osteosarcoma, including prevention of metastatic disease and prevention of amputation in frontline canine osteosarcoma. I intend to lead the regulatory effort with USDA to get OST-HER2 back on the market as a treatment option for canine osteosarcoma."

OST-HER2 was featured in the 2025 documentary 'Shelter Me: Cancer Pioneers' (trailer and full-length film ) that was and won a . OST-HER2's development for canine osteosarcoma was advanced as part of the Comparative Oncology is the study of naturally developing cancers in animals as models for human disease.

About OS Animal Health

OS Animal Health (OSAH) is a wholly owned subsidiary of OS Therapies, Inc. (NYSE American: OSTX) dedicated to improving outcomes for pets with cancer. The company is focused on developing and commercializing OST-HER2, an off-the-shelf immunotherapy candidate for canine osteosarcoma that has previously received conditional approval from the USDA for the treatment of this aggressive bone cancer in dogs. Operating with a separate, animal-health-focused strategy and capital structure, OS Animal Health is working to re-establish USDA conditional approval and bring innovative immunotherapies to the veterinary oncology market, with the goal of extending and improving the lives of dogs living with osteosarcoma, and animals living with other HER2 positive cancers.

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 Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and Fast-Track and Orphan Drug designations from the U.S. FDA and 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. The Company anticipates submitting a Biologics Licensing Application (BLA) to 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. 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.

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 .

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 the 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, most recent Quarterly Report on Form 10-Q 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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