Facts and Hopes in Cancer Antigens Recognized by T Cells.

T cells are key effectors of our immune response against tumors and exert their antitumor effects upon recognizing a variety of tumor-specific peptides presented by HLA molecules on the surface of tumor cells. The identification of the tumor-specific antigens of a given tumor is not required for immune checkpoint therapy (ICT), which mainly reactivates existing tumor-specific T cells together with T cells of unknown specificities. To decrease the activation of non-tumor-specific T cells, active or passive immunizations against tumor-specific antigens are considered.