OS Therapies Launches Subsidiary To Commercialize Canine Osteosarcoma Treatment

(RTTNews) - OS Therapies, Inc. (OSTX), a clinical-stage biopharma company specializing in immunotherapies and antibody-drug conjugates, has launched a new subsidiary, OS Animal Health, Inc., to lead the commercialization of its immunotherapy candidate OST-HER2 for canine osteosarcoma.

The market opportunity for OST-HER2 in treating canine osteosarcoma is estimated to exceed $150 million in the U.S. annually. This projection is supported by recent clinical data demonstrating the drug's effectiveness in both preventing amputations in frontline treatment and controlling metastases. These findings build on earlier data that previously secured a conditional USDA approval for OST-HER2 based on improved overall survival rates post-amputation.

OS Animal Health will apply an updated commercial manufacturing process in its upcoming USDA application for renewed conditional approval, expected in the second half of 2025. The process is backed by a newly issued patent extending protection for OST-HER2 and the company's listeria immunotherapy platform through 2040.

OST-HER2, an off-the-shelf immunotherapy, has shown promising clinical results in both human pediatric and canine osteosarcoma. While OS Therapies plans to submit a request for FDA Accelerated Approval in Q3 2025 for pediatric patients, its animal health subsidiary will independently pursue regulatory approval and commercialization in the veterinary market. This structure will allow OS Animal Health to secure dedicated funding without affecting the parent company's equity.

CEO Paul Romness highlighted that canine osteosarcoma affects over 40,000 dogs annually in the U.S., noting that the subsidiary was created to capitalize on a clear market opportunity to improve canine health outcomes. He emphasized that veterinary oncology differs significantly from human cancer treatment, necessitating a distinct operational and financial model. OS Animal Health aims to begin generating revenue in 2025.

The veterinary oncology market, valued at $1.57 billion, sees canine osteosarcoma accounting for 86% (approx. $1.35 billion) of that total, according to Grandview Research. Currently, standard treatments—chemotherapy, radiation, and surgery—often yield limited success. OST-HER2 is positioned as a less invasive, targeted alternative.

The therapy also features in the PBS documentary Shelter Me: The Cancer Pioneers, which explores comparative oncology between humans and dogs. The film is available for streaming on the PBS website.

OST-HER2 has also been granted Rare Pediatric Disease Designation (RPDD) by the FDA for pediatric osteosarcoma. If it obtains a conditional BLA through Accelerated Review before September 30, 2026, OS Therapies will qualify for a Priority Review Voucher (PRV), which it intends to sell. A recent PRV was sold for $155 million in May 2025.

Thursday, OSTX closed at $1.66, down 7.78%, and is currently trading after hours at $1.68, down 1.20%, on the NYSE American.