Cancer immunotherapy: special issue of BMB Reports in 2021

Basically, cancer is a disease initiated by mutations in the genome. However, cancer is regarded not only as a genetical disease but also an immunological disease because cancer cells can be targeted by the immune system. The immune system recognizes mutated proteins as non-self, foreign antigens, so-called neoantigens, and exerts diverse effector functions to eliminate tumor cells. Anti-tumor immune responses resemble immune responses against viruses. In anti-tumor immune responses, CD8+ and CD4+ T cells are the main effector cells. In addition, dendritic cells (DCs) play a crucial role in the priming of CD8+ and CD4+ T cells, and natural killer (NK) cells also contribute to the anti-tumor immune responses. Recently, immune checkpoint inhibitors (ICIs), including antibodies against cytotoxic T-lymphocyte-associated protein 4 (CTLA- 4), programmed cell death 1 (PD-1), and programmed cell death ligand 1 (PD-L1), became available for the treatment of various types of cancer. Moreover, chimeric antigenic receptor (CAR)-T cells have been successfully used to treat hematologic malignancies. However, current cancer immunotherapy has some limitations. ICIs fail to control tumors in a considerable proportion of cancer patients and CAR-T cell therapy does not effectively control solid tumors. To overcome these limitations, further research and development are required. In the current issue of BMB Reports, seven review articles in the field of cancer immunotherapy were published. [BMB Reports 2021; 54(1): 1-1].