OS Therapies Receives USDA Guidance for OST-HER2 Canine Osteosarcoma

BALTIMORE, Md. — October 7, 2026 — Clinical-stage biopharmaceutical firm OS Therapies (OS Animal Health) announced it has received official regulatory guidance from the United States Department of Agriculture (USDA) Center for Veterinary Biologics establishing the evaluation and submission pathway for its candidate immunotherapy, OST-HER2 (daznelimgene lisbac), in dogs with osteosarcoma. This regulatory clarity establishes a defined pathway toward potential conditional and full USDA licensure for canine bone cancer.

Therapeutic Mechanism & Platform

OST-HER2 utilizes an attenuated, bioengineered Listeria monocytogenes vector designed to deliver HER2/neu tumor-associated antigens directly to antigen-presenting cells. In canine patients diagnosed with osteosarcoma—a highly aggressive malignant bone tumor with high metastatic potential—OST-HER2 stimulates a potent cell-mediated immune response targeting residual microscopic metastatic cells, particularly in the lungs.

Clinical Guidance & Next Steps

The USDA regulatory pathway outlines the specific target animal safety study parameters, field efficacy trial designs, and manufacturing validation requirements necessary for market submission. The alignment provides OS Therapies with a structured roadmap to advance its canine oncology pipeline while serving as a translational clinical model for companion animal care.