OS Therapies, a clinical-stage immunotherapy and antibody drug conjugate (ADC) biopharmaceutical company, announced the launch of OS Animal Health, Inc., a wholly owned subsidiary focused on commercializing OST-HER2 for the treatment of canine osteosarcoma.
OST-HER2 is an off-the-shelf immunotherapy candidate that has shown positive clinical data in both human pediatric and canine osteosarcoma. Parent company OS Therapies is advancing towards an FDA Accelerated Approval submission, anticipated in the third quarter of 2025, for the prevention of recurrence in paediatric patients with fully resected, lung-metastatic osteosarcoma. Concurrently, its wholly-owned subsidiary, OS Animal Health, is focused on re-establishing USDA conditional approval for OST-HER2 in canine osteosarcoma, with a targeted submission in the second half of 2025.
“Osteosarcoma is the most common canine cancer, affecting more than 40,000 dogs in the US each year,” said Paul Romness, CEO of OS Therapies. “Given the recent issuance of a new patent protecting the commercial manufacturing process for OST-HER2 and the rest of our listeria immunotherapy platform into 2040, we now have a clear commercial opportunity to greatly improve health outcomes in this deadly canine cancer through OS Animal Health.”
To advance OST-HER2 in the veterinary space with the attention it deserves, OS Animal Health will operate independently from the parent company, with separate funding aligned to the needs of the animal health market.
“Selling into the animal health cancer market is substantially different than selling into the human cancer market, and as such we have created this new corporate structure that will be capitalized separately and independently from the parent company’s balance sheet so that we can deliver on this unique market opportunity without diluting OS Therapies share structure,” Romness added. “Our current animal health advisors are providing the clinical and regulatory expertise we need to move the USDA process forward. We expect OS Animal Health to begin generating revenue as early as 2025.”
According to Grandview Research, the veterinary oncology market is valued at 1.57 billion, with canine osteosarcoma representing 86% of the total – approximately $1.35 billion. OS Therapies estimates OST-HER2’s addressable opportunity in US canine osteosarcoma to be over $150 million.
The canine osteosarcoma treatment market is currently dominated by chemotherapy, radiation therapy, and surgical procedures such as amputation and tumour resection – approaches that often result in limited overall survival outcomes. OST-HER2 has the potential to significantly improve how this aggressive cancer is treated in dogs, offering a less invasive and more targeted alternative to current options.
OST-HER2 is also featured in the PBS documentary Shelter Me: The Cancer Pioneers, which offers a look into canine comparative oncology, a field that compares treatment of cancers in dogs to those in people and covers developing treatments for rare forms of cancer. The movie is available via streaming on the PBS website.
OST-HER2, being developed by parent company OS Therapies, Inc. for paediatric osteosarcoma, has received Rare Paediatric Disease Designation (RPDD) for osteosarcoma from the US FDA, and if it receives a conditional BLA via Accelerated Review prior to September 30, 2026, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to immediately sell. The most recent PRV sale, valued at $155 million, occurred in May 2025.
OS Therapies is a clinical stage oncology company focused on the identification, development, and commercialization of treatments for osteosarcoma and other solid tumours.
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