[Strategical consideration of the interaction between tumor microenvironment and tumor immunity]

In cancer immunotherapy, the importance of tumor microenvironment (TME) has recently been highlighted. TME, where trafficked T lymphocytes with tumoricidal activity, particularly endowed by dendritic cells in the sentinel lymph nodes, suppress cancer cells, consists of multiple cellular components, such as fibroblasts, macrophages, myeloid-derived suppressor cells, monocytes, neutrophils, regulatory T cells, and NK cells, and non-cellular components, such as extracellular matrix and blood and lymphatic vessels. These stroma-forming components have been demonstrated to be mutually interrelated and to provide pro-cancer propensity. The recent clinical success of immune checkpoint inhibitors in cancer treatment has again highlighted the importance of controlling the immunosuppressive milieu of TME to achieve an improved clinical outcome. Simultaneously, understanding the unsuccessful clinical efficacy mediated by adoptively transferred cancer antigen receptor gene-modified T cells against solid tumors has similarly drawn a conclusion. This review presents some recent and notable progresses in cancer immunotherapy, thus aiming at an opportunity to understand the interrelation between tumor immunity in cancer-bearing host and TME.