OS Therapies Incorporated

What they do

OS Therapies is a clinical-stage biopharmaceutical company focused on developing treatments for osteosarcoma and other solid tumors. Its lead candidate, OST-HER2 (OST31-164), is a cancer immunotherapy designed to produce a cellular immune response against the HER2 antigen. The company also owns the OST-tADC platform, a next-generation antibody-drug conjugate technology using silicone dioxide linkers. As of the latest filings, the company has not generated any revenue from drug sales.

Revenue drivers

• OST-HER2 — Lead product candidate targeting recurrent, fully resected pulmonary metastatic osteosarcoma; no revenue yet, but Phase IIb data showed 75% two-year overall survival vs. 40% historical control.
• OST-tADC platform — Next-generation antibody-drug conjugate platform, still pre-clinical; potential future revenue if developed.
• Potential expansion into other solid tumors — Company plans to evaluate OST-HER2 in breast, esophageal, and lung cancers, alone or with HER2-targeting antibodies, but no products are commercialized.

Recent performance

For fiscal year 2025, net loss was $28.8 million, up from $8.9 million in 2024 and $7.8 million in 2023. Diluted EPS improved to -$0.98 in 2025 from -$1.28 in 2024, but operating cash flow worsened to -$14.2 million in 2025 from -$7.3 million in 2024. As of March 31, 2026, the company had cash and equivalents of $917,552, total assets of $7.3 million, and total liabilities of $17.1 million, resulting in negative shareholder equity of $10.8 million. The independent registered public accounting firm has expressed substantial doubt about the company's ability to continue as a going concern.

Strategy

The company is focused on obtaining regulatory approval for OST-HER2 in osteosarcoma. It has submitted non-clinical and CMC modules of its BLA to the FDA and expects to submit the clinical module after a Type B meeting in Q2 2026. It also plans to submit conditional MAA filings to the MHRA and EMA in Q2 2026 and initiate confirmatory studies in Q3 2026. If approved under the FDA's Accelerated Approval Program before September 30, 2029, the company would be eligible for a Priority Review Voucher. The company also intends to explore OST-HER2 in other solid tumors and develop its OST-tADC platform.

Risks

• Going concern risk — Independent auditors have expressed substantial doubt about the company's ability to continue as a going concern due to negative equity and limited cash.
• No revenue and reliance on funding — The company has no product revenue and must raise capital to fund operations; failure to do so would delay or discontinue programs.
• Regulatory and approval uncertainty — OST-HER2 is not yet approved; regulatory pathways are uncertain and delays in approval would prevent commercialization.
• Dependence on single product candidate — The company relies heavily on OST-HER2, and setbacks in its development would materially harm the business.

Outlook

Management expects to engage with the FDA regarding potential regulatory pathways and to release additional biomarker data in Q2 2026. The company anticipates submitting the clinical BLA module in Q2 2026 and completing conditional MAA submissions to the MHRA and EMA in the same period. Confirmatory clinical studies are expected to begin in Q3 2026. However, the company's ability to fund these activities is uncertain given its cash position of $917,552 as of March 31, 2026.