CTLA4 and neoplasm: Combination treatments with radiotherapy and anti-PD-1 antibodies or anti-CTLA-4 antibodies could activate tumor-specific T cells in the tumor microenvironment (TME), increase the infiltration of CD8-positive T cells, and reduce the accumulation of myeloid-derived suppressor cells (MDSCs) and regulatory T cells, thereby improving anti-tumor immunity (41–44).