Monocyte maturation mediators upregulate cd83, icam-1 and mhc class 1 expression on ewing’s sarcoma, enhancing t cell cytotoxicity

Ewing’s sarcoma (EwS) is a pediatric solid tumor entity with low somatic mutational burden and a low rate of tumor-infiltrating T cells, indicating a low extent of immunogenicity. In EwS, immunogenicity may furthermore be significantly diminished by a predominantly M2 macrophage driven pro-tumorigenic tumor microenvironment. In the past, we demonstrated that CHM1³¹⁹-specific TCR-transgenic T cells are able to control EwS growth in a preclinical mouse model as well as in a patient with metastatic disease. However, new adjuvant techniques to induce long lasting and curative CHM1³¹⁹-specific TCR-transgenic T cell-mediated anti-tumor responses are needed. In this work, we sought to identify a technique to improve the cytotoxic effect of CHM1³¹⁹-specific TCR-transgenic T cell by altering the immunogenic cell surface marker expression on EwS cell lines using different cytokines. We demonstrate that TNF, IL-6, IL-1β and PGE₂ cause pro-immunogenic CD83, MHC class I and II as well as ICAM-1 upregulation in EwS cell lines. This observation was associated with significantly improved recognition and killing of the tumor cells by EwS-specific CHM1³¹⁹ /HLA-A*02:01-restricted TCR-transgenic T cells. Conclusively, we demonstrate that the induction of an inflammatory signature renders EwS more susceptible to adoptive T cell therapy. TNF, which is upregulated during inflammatory processes, is of particular translational interest as its secretion may be induced in the patients e.g., by irradiation and hyper-thermia in the clinical setting. In future clinical protocols, this finding may be important to identify appropriate conditioning regimens as well as point of time for adoptive T cell-based immunotherapy in EwS patients.