CCL2 and neoplasm: Interestingly, experimental evidence suggests that blocking macrophage recruitment to untreated, and thus immunosuppressive, tumors is clinically beneficial.26,31,85,121 In contrast, in vivo repolarization of highly effective, tumor-clearing macrophages in tumors is dependent upon CCL2 signaling for additional monocyte/macrophage recruitment.137 These findings highlight the significance of the pro- or anti-inflammatory state of the TME and suggest that effective macrophage-targeting immunotherapy will require a clear understanding of the immunologic context of TAMs prior to treatment.