13 Feb 2026
OS Therapies is working to roll out listeria-based immunotherapy for both dogs and humans.
Chris Simpson
Job Title
Image: © Design Cells / Adobe Stock
Data from an osteosarcoma trial in dogs has been used to identify a biomarker pathway that has been linked to longer survival in humans.
Clinical stage oncology company OS Therapies announced positive biomarker data from its phase 2b clinical trial of OST-HER2, a listeria-based immunotherapy, in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma in humans.
The company found that activation of immune blood biomarkers in the interferon gamma pathway was predictive of overall survival, distinguishing long term survivors (older than 2 years) from short-term survivors (below 1 year).
Its biomarker pathway strategy was pre-specified based on data generated from a 2025 study of 118 canine metastatic osteosarcoma patients.
OS Therapies chief executive Paul Romness said: “Leveraging the power of comparative oncology, we were able to train and test potentially predictive biomarkers from the canine metastatic osteosarcoma trial in order to form a hypothesis to test in a pre-specified way in the human metastatic osteosarcoma trial.
“We believe the confirmation of this pre-specified pathway analysis in humans adds significant resolution to our clinical data, increasing the clinical interpretability of the two-year overall survival data for regulatory agencies.
“The confirmation of a pre-specified canine biomarker pathway being upregulated in a comparable human clinical study population leveraged canine biomarker data to a generate hypothesis that was tested in a pre-specified way and confirmed as a surrogate marker of clinical efficacy.”
He suggested the biomarker data strengthens the company’s pending Biologics License Application (BLA) submission.
OS Therapies is planning a BLA submission to the US Food and Drug Administration (FDA) and has pending marketing authorisation application submissions in the UK and Europe.
It is aiming to gain regulatory approval for OST-HER2 in the UK by the end of this year’s second quarter, the US by the end of the third quarter and Europe by year end.
The company’s wholly owned subsidiary, OS Animal Health Corp (OSAH), announced plans to trade on the NYSE American or Nasdaq Capital Markets national stock exchange in the first half of 2026.
OST-HER2 has previously been conditionally approved by the US Department of Agriculture (USDA) for the treatment of dogs with osteosarcoma, and OSAH will primarily focus on re-establishing its approval and commercialisation.
OSAH CVO Edward Robb said: “Canine osteosarcoma remains one of the most deadly forms of cancer in dogs.
“OST-HER2 has demonstrated potential to significantly improve patient outcomes in multiple research studies of canine osteosarcoma, including prevention of metastatic disease and prevention of amputation in frontline canine osteosarcoma.
“I intend to lead the regulatory effort with USDA to get OST-HER2 back on the market as a treatment option for canine osteosarcoma.”
