New York, March 27, 2026
OS Therapies has achieved a significant regulatory milestone by securing meetings with multiple global health authorities, including the U.S. Food and Drug Administration, European Medicines Agency, Medicines and Healthcare products Regulatory Agency, and Therapeutic Goods Administration. These discussions aim to review and align on the design of a global confirmatory Phase 3 clinical trial for the company’s lead immunotherapy candidate OST-HER2, targeting metastatic osteosarcoma, a rare and aggressive bone cancer with limited treatment options. The meetings are scheduled for the second quarter of 2026, with trial initiation expected in the third quarter of 2026, beginning in Australia.
Global Regulatory Alignment for Accelerated Approval
The coordinated engagement with multiple regulatory agencies marks a crucial step toward potential accelerated approval pathways. The planned Phase 3 trial is a prerequisite for submitting a Biologics License Application (BLA) in the United States and obtaining Conditional Marketing Authorisations (CMAs) in Europe and the United Kingdom.
OS Therapies aims to secure these approvals in the second half of 2026, highlighting the urgency to address unmet needs in patients with advanced osteosarcoma. The company has also confirmed that it is on track to deliver clinical and biomarker data requested by regulators ahead of a key pre-BLA meeting, reinforcing confidence in the therapy’s development pathway. This synchronized global regulatory strategy reflects increasing collaboration among agencies to accelerate innovative cancer treatments to market.
Innovative Immunotherapy Targeting HER2
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OST-HER2 represents a novel approach in oncology, utilizing a Listeria-based immunotherapy platform designed to stimulate the immune system to target HER2-expressing tumor cells. The therapy has already demonstrated statistically significant improvements in event-free survival and overall survival in earlier clinical studies, positioning it as a promising candidate for patients with limited options. Importantly, OST-HER2 has received multiple regulatory designations, including Orphan Drug Designation, Fast Track Designation, and Rare Pediatric Disease Designation, underscoring its potential impact in rare cancers. These designations may also enable incentives such as a Priority Review Voucher (PRV) upon approval, further enhancing its commercial and strategic value.
Addressing Critical Unmet Needs in Osteosarcoma
Metastatic osteosarcoma remains a devastating condition, particularly affecting children and young adults, with no significant advancements in standard of care for over four decades. OS Therapies is positioning OST-HER2 as a first-in-class immunotherapy capable of transforming treatment outcomes. The therapy’s ability to activate immune responses while maintaining favorable tolerability makes it a strong candidate for early market access programs. In parallel, the company has initiated market access and health technology assessment (HTA) activities in Europe, preparing for potential commercialization. With regulatory momentum building and Phase 3 trials on the horizon, OST-HER2 could represent a breakthrough advancement in rare pediatric oncology, offering new hope to patients facing this life-threatening disease.
Source: OS Therapies press release
