CTLA4 and neoplasm: Meanwhile, tumor cells employ various immunosuppressive factors, including immune checkpoint molecules like CTLA4 and PD-1, as well as immunosuppressive cells like regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages (TAMs).9 TAMs not only produce immunosuppressive cytokines such as TGFβ and IL-10 but also VEGFs (vascular endothelial growth factors).