The elucidation of tumor immunosuppression affected by cancer-associated fibroblasts

Development of immunotherapy, especially checkpoint inhibitors, dramatically improved the prognosis of some malignancies. However, problems on the occurrence of severe adverse effects and limited responses to these checkpoint inhibitors remain. Recently, tumor infiltrating lymphocytes (Tils) are the predictive markers of immunotherapies based on clinical evidence. The proportion of cytotoxic T cells in the tumor has been reported to affect the antitumor effect. TILs in the tumor are thought to be controlled by the interaction between cancer and tumor microenvironment. As a cause of tumor immunosuppression, cancer-associated fibroblasts (CAFs) play the main role in the tumor microenvironment. We considered the strong involvement of tumor microenvironment, particularly the role of CAFs, and reported the interaction between CAFs and proliferation, invasion, angiogenesis, and resistance in the conventional therapy. The correlation between CAFs and tumor immunity and the immunosuppression promoted by CAFs were also evaluated. Their effects will be reported in our future studies.