Human HLA-A*02:01/CHM1(+) allo-restricted T cell receptor transgenic CD8(+) T Cells specifically inhibit Ewing sarcoma growth in vitro and in vivo

The endochondral bone protein Chondromodulin-I (CHM1) provides oncogene addiction in Ewing sarcoma (ES). We pre-clinically tested the targetability of CHM1 by TCR transgenic, allo-restricted, peptide specific T cells to treat ES. We previously generated allo-restricted wildtype CD8(+) T cells directed against the ES specific antigen CHM1(319) causing specific responses against ES. However, utilization of these cells in current therapy protocols is hampered due to high complexity in production, relatively low cell numbers, and rapid T cell exhaustion. In order to provide off-the-shelf products in the future, we successfully generated HLA-A*02:01-restricted T cell receptor (TCR) transgenic T cells directed against CHM1(319) by retroviral transduction. After short-term expansion a 100% purified CHM1(319)-TCR-transgenic T cell population expressed a CD62L(+)/CD45RO and CD62L(+)/CD45RA(+) phenotype. These cells displayed specific in vitro IFNg and granzyme B release in co-culture with HLA-A*02:01(+) ES cell lines expressing CHM1. When co-injected with ES cells in Rag2(−/−)ɣc(−/−) mice, CHM1-specific TCR-transgenic T cells significantly inhibited the formation of lung and liver metastases in contrast to control mice. Lungs and livers of representative mice displayed CD8(+) T cell infiltration in the presence (control group treated with unspecific T cells) and in the absence (study group) of metastatic disease, respectively. Furthermore, mice receiving unspecific T cells showed signs of graft-versus-host-disease in contrast to all mice, receiving CHM1(319)-TCR-transgenic T cells. CHM1(319) specific TCR-transgenic T cells were successfully generated causing anti-ES responses in vitro and in vivo. In the future, CHM1(319)-TCR-transgenic T cells may control minimal residual disease rendering donor lymphocyte infusions more efficacious and less toxic.