NEW YORK, March 31, 2026 — OS Therapies, Inc
a clinical-stage oncology company specializing in listeria-based cancer immunotherapies, has announced the completion of its biomarker and clinical data submission to the U.S. Food and Drug Administration (FDA) in preparation for a pivotal Pre-Biologics License Application (Pre-BLA) meeting. This milestone represents a major step forward for its lead candidate OST-HER2, which targets osteosarcoma, a rare and aggressive form of bone cancer. The company also reported its full-year 2025 financial results and outlined an ambitious regulatory roadmap aimed at securing accelerated approval in the United States and conditional authorizations in Europe and the United Kingdom by late 2026.
Biomarker Strategy Strengthens Accelerated Approval Pathway
A key highlight of the announcement is the FDA’s alignment with OS Therapies on the use of immune biomarkers as surrogate endpoints for clinical efficacy, a strategy that could significantly expedite the regulatory pathway. The company confirmed that pre-specified immune biomarker signatures demonstrated strong correlation with clinical outcomes, reinforcing their potential to support a Biologics License Application under the Accelerated Approval Program.
This approach is particularly important in rare cancers like osteosarcoma, where traditional large-scale trials can be challenging. By leveraging validated biomarker-driven endpoints, OS Therapies aims to accelerate patient access to innovative treatments while maintaining robust scientific standards. The upcoming Pre-BLA meeting expected in May 2026 will be critical in confirming the regulatory framework and final requirements for submission.
In parallel, the company is advancing discussions with global regulators, including the European Medicines Agency (EMA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA), with plans to submit Marketing Authorization Applications (MAAs) in April 2026. These coordinated global efforts position OST-HER2 as a strong candidate for multi-regional approvals within a compressed timeline..
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Clinical Data Demonstrates Strong Survival Outcomes
The Phase 2b clinical trial of OST-HER2 has delivered promising results, achieving statistically significant improvements in both event-free survival (EFS) and overall survival (OS). Notably, the company reported 75% two-year overall survival, a meaningful outcome in a disease setting with limited treatment options.
The therapy is designed to harness the immune-stimulatory properties of Listeria-based technology, targeting the HER2 protein to trigger a robust anti-tumor immune response. This innovative mechanism differentiates OST-HER2 from conventional therapies and underscores its potential as a next-generation immunotherapy for solid tumors.
Additionally, regulatory momentum has been strengthened by multiple designations, including Orphan Drug Designation, Fast Track Designation, and Rare Pediatric Disease Designation from the FDA, as well as Advanced Therapy Medicinal Product (ATMP) designation from the EMA. These recognitions not only validate the therapy’s potential but also provide regulatory incentives such as expedited review timelines and potential eligibility for a Priority Review Voucher (PRV).
The convergence of strong clinical outcomes, regulatory alignment, and biomarker validation significantly enhances the probability of accelerated approval, offering new hope for patients with limited therapeutic options.
Global Expansion and Strategic Growth Outlook
Beyond regulatory progress, OS Therapies is actively positioning itself for commercialization and long-term growth. The company plans to initiate a confirmatory Phase 3 clinical trial in Australia in the third quarter of 2026, aimed at validating efficacy data and supporting full approval pathways.
Strategically, the company has strengthened its pipeline through the acquisition of a listeria monocytogenes immunotherapy platform, reducing future financial obligations and enhancing its intellectual property portfolio, with patents extending through 2040. Furthermore, a commercialization partnership and ongoing capital raises are supporting the transition from clinical development to market readiness.
The company is also expanding into comparative oncology, leveraging canine osteosarcoma models to inform human clinical development, a novel approach that highlights the translational potential of its platform. In parallel, its subsidiary initiatives aim to drive veterinary applications and broaden therapeutic impact across species.
With anticipated regulatory decisions in the second half of 2026, OS Therapies is entering a transformative phase, where successful approvals could establish OST-HER2 as a first-in-class immunotherapy for osteosarcoma. The company’s integrated strategy—combining innovative science, regulatory acceleration, and global expansion—positions it at the forefront of oncology innovation.
Source: OS Therapies press release
