NEW YORK and ROCKVILLE, Md., May 29, 2026
OS Therapies announced the publication of four scientific articles focused on OST-HER2 and osteosarcoma in Drug Discovery World, while reaffirming plans to present 2.5-year overall survival data from its Phase 2b clinical trial at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. The upcoming presentation is expected to provide an important update on the potential of OST-HER2 to prevent or delay recurrence in patients with fully resected pulmonary metastatic osteosarcoma, a rare and aggressive bone cancer with limited treatment options.
Scientific Publications Reinforce Focus on Osteosarcoma Innovation
The four published articles explore critical issues shaping the future of osteosarcoma treatment, including advances in drug development, comparative oncology, regulatory science, and accelerated approval pathways. The publications examine how canine osteosarcoma models can support biomarker discovery and therapy development, while also addressing the need for regulatory flexibility to accelerate access to innovative treatments for patients facing significant unmet medical needs. Together, these articles underscore the growing scientific and regulatory momentum behind efforts to improve outcomes for osteosarcoma patients and support the advancement of novel therapeutic approaches such as OST-HER2.
Phase 2b Trial Data Position OST-HER2 for Regulatory Advancement
OST-HER2 is an investigational cancer immunotherapy that utilizes a gene-edited Listeria-based platform designed to stimulate a targeted immune response against the HER2 protein. The therapy has already demonstrated encouraging results in a Phase 2b study involving patients with recurrent, fully resected lung metastatic osteosarcoma. According to the company, the trial achieved clinically meaningful improvements in the 12-month event-free survival (EFS) primary endpoint and the overall survival (OS) secondary endpoint. The upcoming ASCO presentation will provide extended follow-up data, including 2.5-year overall survival outcomes that could further strengthen the therapy’s clinical profile and support future regulatory submissions.
Advertisement
Multiple Regulatory Designations Support Development Strategy
The development of OST-HER2 has received significant regulatory recognition from both U.S. and European authorities. The therapy has been granted Orphan Drug Designation (ODD), Fast Track Designation (FTD), and Rare Pediatric Disease Designation (RPDD) by the U.S. Food and Drug Administration, as well as ODD, FTD, and Advanced Therapy Medicinal Product (ATMP) designation from the European Medicines Agency. These designations are intended to accelerate development and review processes for therapies targeting rare and serious diseases. OS Therapies plans to seek a Biologics License Application (BLA) for OST-HER2 in the United States during the second half of 2026 and is also pursuing Conditional Marketing Authorizations (CMAs) in Europe, the United Kingdom, and Australia.
Building a Broader Oncology Pipeline
Beyond osteosarcoma, OS Therapies continues to expand its oncology pipeline through additional clinical and preclinical programs. The company reported that OST-HER2 has completed a Phase 1 clinical study in breast cancer patients and has shown promising preclinical activity in multiple breast cancer models. The therapy has also received conditional approval from the U.S. Department of Agriculture for the treatment of canine osteosarcoma, highlighting its potential across both human and veterinary oncology. Additionally, the company expects to report data from a Phase 1b study of OST-504 in castration-resistant prostate cancer. With multiple development programs advancing simultaneously, OS Therapies aims to strengthen its position as a leader in Listeria-based cancer immunotherapies while addressing critical unmet needs in rare and difficult-to-treat cancers.
Source: OS Therapies press release
