INTRODUCTION: Soft tissue sarcomas (STSs) are malignant tumors arising from mesenchymal tissues. Patients with advanced and metastatic STSs have low overall survival rates and relatively limited treatment options. Oncostatin M (OSM) is a pleiotropic cytokine that was shown to carry both pro- and anti-tumorigenic properties in various cancer types. However, the role of OSM in STSs has not yet been elucidated. Moreover, the potential additive effects of combining OSM and anti-PD-1 therapy have not been carried out so far. METHODS: The aim of this study was to determine the effects of in vitro OSM administration on liposarcoma, leiomyosarcoma, and myxofibrosarcoma immune cells isolated from peripheral blood and tumor tissues and the potential cooperative nature of OSM and nivolumab in treating these STSs. We designed a cohort study to explore novel histology-driven therapies in our target STSs. The immune cells were isolated from the peripheral blood and tumors of patients with STS, and the proportions and phenotypes of immune cells were evaluated with flow cytometry after cultivation with therapeutic monoclonal antibodies. RESULTS: The proportion of peripheral CD45+ cells was not affected by OSM but was significantly increased by nivolumab, whereas both treatments had an effect on CD8+ T cells. In tumor tissues, CD8+ T cell and CD45‒ TRAIL+ cell cultures were boosted by nivolumab and significantly enriched by OSM. Our data suggest that OSM may play a role in the treatment of leiomyosarcoma, myxofibrosarcoma, and liposarcoma. CONCLUSION: In conclusion, the biological efficacy of OSM is reflected in the tumor microenvironment rather than in the peripheral blood of the patients in our cohort, and nivolumab could potentiate its mechanism of action in selected cases. Nevertheless, more histotype-tailored studies are needed to fully understand the functions of OSM in STSs.

3rd Department of Surgery 1st Faculty of Medicine Charles University and University Hospital Motol Prague Czechia

Chemokine Research Group Institute of Infection Immunity and Inflammation College of Medical Veterinary and Life Sciences University of Glasgow Glasgow UK

Department of Immunology 2nd Faculty of Medicine Charles University and University Hospital Motol Prague Czechia

Department of Methodology Faculty of Physical Education and Sport Charles University Prague Czechia

Department of Surgery Oncology and Gastroenterology University of Padova Padova Italy

Veneto Institute of Oncology IOV IRCCS Padova Italy

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