OS Therapies Incorporated reported on Thursday that new biomarker analyses from its ongoing Phase 2b trial of OST-HER2 in recurrent, fully resected lung-metastatic osteosarcoma demonstrated a statistically significant increase in 12-month event-free survival (EFS), the study’s primary endpoint. According to company data, patients receiving OST-HER2 showed a 35% improvement in key immune activation signatures—including elevated CD8+ T-cell infiltration and interferon-gamma expression—compared with historical controls. The complete biomarker dataset is slated for public release on January 15, 2026, and will underpin the company’s planned submission of a Biologics License Application (BLA) to the U.S. Food and Drug Administration under the Accelerated Approval Program. Following the announcement, shares of OS Therapies declined on the New York exchange as investors reassessed the timing and likelihood of regulatory approval.

OS Therapies’ wholly owned subsidiary, OS Animal Health Corp., has filed a Form S-1 with the U.S. Securities and Exchange Commission in anticipation of an initial public offering on either the NYSE American or Nasdaq Capital Markets in the first half of 2026. Under the planned spin-off structure, existing OSTX shareholders will receive one share of OS Animal Health for every ten shares of OS Therapies held as of the subsidiary’s yet-to-be-determined record date. OS Animal Health will focus on re-establishing USDA conditional approval and commercializing OST-HER2 for canine osteosarcoma and other HER2-positive veterinary cancers. The global veterinary oncology market reached $1.58 billion in 2024 and is projected to grow to $4.77 billion by 2034, with the canine cancer segment accounting for over 86% of revenues and forecasting a 12.56% compound annual growth rate through 2030.