CD4 and neoplasm: Previous studies have shown that the infiltration of lymphocytes, such as CD4+ T cells, NK cells, and plasma cells, was high in the tumor microenvironment (Almatroodi et al., 2016; Engblom et al., 2016; Jiang et al., 2016; Jain et al., 2017; Janakiram et al., 2017; Pierce et al., 2017; Song et al., 2017) and that the effectiveness of immunotherapy may be attributed to the upregulation of ICGs (e.g., programmed death-1, programmed death ligand-1, and cytotoxic T lymphocyte antigen-4) (Llosa et al., 2015).