CD4 and neoplasm: Prior studies have identified changes in the tumor microenvironment in response to management with EGFR TKIs, resulting in changes including alterations in the populations of tumor infiltrating lymphocytes (TILs), such as an increase number of effector CD8 + T cells and increased antitumor CD4 + T cells, increased M1 tumor-associated macrophages (TAMs) and decreased M2 TAMs, increased MHC I and MHC II expression, and increased secretion of pro-inflammatory cytokines [29, 30].