CD4 and neoplasm: Increasingly, researchers have combined the immune-activating effects of PDT with immunotherapies that enhance tumor immunogenicity (e.g., immunoadjuvants) or immunotherapies that reduce immunosuppression in the tumor microenvironment (e.g., immune checkpoint inhibitors, anti-PD-1, anti-PD-L1, and anti-CTLA4 antibodies, etc.), which ultimately increased tumor infiltration of cytotoxic CD4+/CD8+ T cells and memory T cells that produced significant antitumor effects, as shown in Figure 6.