OS Therapies is a clinical-stage biopharmaceutical company focused on developing treatments for osteosarcoma, a rare and aggressive bone cancer that primarily affects children and young adults. The company has no approved products and no commercial revenue. OS Therapies' lead program is OST-HER2, a cancer immunotherapy that uses a genetically weakened strain of the bacterium *Listeria monocytogenes* to stimulate the immune system to attack HER2-expressing cancer cells. OST-HER2 is designed for patients following surgical removal of osteosarcoma that has spread to the lungs. OST-HER2 has completed a Phase IIb trial and met its primary endpoint, and OS Therapies is now pursuing FDA Accelerated Approval and preparing Biologics License Application submissions in the U.S., U.K., and EU. Beyond osteosarcoma, OS Therapies intends to evaluate OST-HER2 in other HER2-expressing solid tumors. The company also has two early-stage Listeria-based programs in lung and prostate cancer, acquired from Ayala Pharmaceuticals in April 2025, and a preclinical antibody-drug conjugate platform targeting folate receptor alpha in ovarian and endometrial cancers. OS Therapies funds operations through equity and debt issuances, and outsources all manufacturing and research chemistry, keeping its headcount minimal. If approved, OS Therapies would sell OST-HER2 directly to oncology centers serving a small patient population of roughly 1,000 U.S. cases per year.