Since TAMs are a heterogeneous population of cells, and could re-polarize from immunosuppressive M2 phenotypes to classically activated phenotypes by immunotherapy such as type 1 IFN [45] and anti-PD1 Abs [4], these reagents could inhibit migration of CCR2+ MDSCs and CCR4+ Tregs to the tumor site to induce anti-tumor immune responses in the tumor-bearing host. Here, CCR4 is linked to neoplasm.