OS Therapies Inc. Advances Toward Potential 2026 Osteosarcoma Treatment Launch with FDA RMAT Designation and Strong Clinical Data

Stonegate Capital Partners has initiated coverage on OS Therapies Inc. (NYSE: OSTX), highlighting the company's significant progress in advancing OST-HER2 toward potential regulatory approval and commercialization. The therapy has demonstrated compelling efficacy in osteosarcoma, an area with no new FDA-approved therapies in over 40 years, making this development particularly important for patients with recurrent, fully resected, pulmonary metastatic osteosarcoma.

The FDA confirmed that OST-HER2 meets the biological definition of a Regenerative Medicine Advanced Therapy (RMAT) and issued a Biologics License Application (BLA) number in preparation for an Accelerated Approval submission. Final 12-month Event Free Survival (EFS) results from the Phase 2b trial demonstrated statistically significant improvement, supported by interim 2-year Overall Survival (OS) data, further validating the clinical benefit of the treatment approach.

OS Therapies has secured a U.S. commercial partnership with Eversana, positioning the company for a potential U.S. launch in the first half of 2026. The therapy, built on a listeria-based immunotherapy platform, represents a novel approach to treating osteosarcoma. The company's regulatory advancements include a productive End of Phase 2 Meeting with the FDA in August 2025, where they aligned on CMC and non-clinical matters and confirmed no safety concerns with OST-HER2.

Internationally, OS Therapies has submitted an ILAP to the UK MHRA and scheduled an EMA rapporteur meeting in October 2025, with agencies signaling an intent to synchronize reviews via Project Orbis. The rare pediatric disease designation for OST-HER2 could qualify the company for a Priority Review Voucher (PRV) if approved before September 30, 2026, potentially monetizable at approximately $155–160 million based on recent transactions.

Financially, OS Therapies reported a net loss of $4.5 million for 2Q25, compared to $1.6 million in 2Q24, reflecting increased R&D and G&A expenses related to clinical and regulatory progress. The company maintains cash of $2.8 million at quarter-end, with recent financing extending runway into 2027 through warrant exchanges and inducement transactions totaling $7.9 million. Management expects this strengthened balance sheet, combined with potential PRV monetization, to provide multi-year capital runway to support commercialization efforts.