Stonegate Capital Partners has updated its coverage on OS Therapies Inc. (NYSE: OSTX), highlighting the company's advancement of key clinical, regulatory, and commercial milestones during the third quarter of 2025. The biopharmaceutical company is moving closer to bringing its lead candidate, OST-HER2, to patients with recurrent, fully resected, pulmonary metastatic osteosarcoma.
Final two-year overall survival data from the 41-patient Phase 2b trial showed a 75% survival rate for patients treated with OST-HER2, compared to 40% in historical controls. Notably, 100% of patients who were event-free at 12 months survived to the two-year mark, reinforcing the treatment's durable benefit. Building on a successful End-of-Phase 2 interaction with regulators, management is preparing harmonized filings for both U.S. and international markets.
The company expects to submit applications to the UK Medicines and Healthcare products Regulatory Agency (MHRA) and the U.S. Food and Drug Administration (FDA) around year-end. This regulatory push is supported by OS Therapies' partnership with Eversana and a commercial launch plan that anticipates initial Priority Review Voucher monetization in 2026 and commercial OST-HER2 revenues beginning in early 2027. The company has secured a UK MHRA pre-MAA meeting and an FDA Type C meeting, both scheduled for the fourth quarter of 2025, with plans for a UK Marketing Authorization Application submission and a U.S. Biologics License Application filing in January 2026 under Project Orbis.
In parallel regulatory developments, the UK MHRA has accepted the use of historical controls and real-world comparators for a conditional marketing authorization application, while the European Medicines Agency has provided feedback supporting the use of two-year overall survival from the Phase 2b trial as the primary efficacy endpoint for conditional approval. The FDA has aligned with the company on safety, non-clinical, and chemistry, manufacturing, and controls requirements, with ongoing discussions around applying updated overall survival-focused oncology guidance to the existing efficacy package.
Subsequent to the quarter-end, OS Therapies announced its intent to spin off OS Animal Health (OSAH) into a separately financed, standalone public company in the first half of 2026. OSTX shareholders are expected to receive direct equity participation in the new listing. OS Animal Health targets a substantial U.S. canine osteosarcoma opportunity and will be housed within OSAH as a standalone public entity.
Beyond its lead asset, OS Therapies continues to leverage the acquired Ayala/Advaxis listeria platform. The OST-504 Phase 1b trial in biochemically recurrent prostate cancer has completed its last patient visit, with an initial data readout expected in the fourth quarter of 2025.
Financially, OS Therapies reported a net loss of $6.9 million for the third quarter of 2025, compared to $2.9 million in the same period last year. This increase was driven primarily by higher regulatory and pre-commercial spending ahead of OST-HER2 filings. The company ended the quarter with approximately $1.9 million in cash and equivalents, supplemented by post-quarter proceeds tied to a previously announced approximately $7.8 million warrant exercise and inducement exchange, extending the company's financial runway into late 2026. During the quarter, OSTX terminated an equity line of credit and established an at-the-market program, adding flexibility as it positions the balance sheet for potential OST-HER2 approval and Priority Review Voucher monetization ahead of the September 30, 2026 sunset date.
Stonegate Capital Partners uses a probability-adjusted Discounted Cash Flow Model when valuing OSTX, returning a valuation range of $5.59 to $7.58 with a midpoint of $6.44. The firm notes that this model is highly leveraged to future years due to the long-term nature of OS Therapies' industry, leading to potential for significant re-ratings as new information becomes available.
