The mechanism of increasing infiltration of CD8+ cytotoxic T cells after chemotherapy might be that chemotherapy like gemcitabine, 5-Fluorouracil, etc, might decrease Treg and MDSC numbers and increase pro-inflammatory cytokines (such as IFN-γ, IL-2, IL-6, etc) in the tumor region, leading to T cell infiltration to the tumor (24, 25), though further validation is needed. This evidence concerns the gene IL2 and neoplasm.