CCL2 and cancer: Beyond GM-CSF, cytokines such as IL-17, IL-34, CXCL4, CXCL12, CCL2, CCL5, CCL20, and CSF2 also play significant roles in TAM recruitment, with other tumor-associated stromal cells participating in this process.21,447–455 Pan-cancer analysis has revealed that macrophages are significantly expanded in the blood of most cancer patients, and the number of macrophages is notably higher in patients who are non-responsive to immune checkpoint inhibitors compared to those who are responsive.