CCL2 and neoplasm: Inhibiting CCL2‐CCR2 has shown benefits to inhibition of tumor growth in many types of tumor models including prostate, mammary carcinoma, lung cancer, hepatocellular cancer, liver cancer, PDAC, and melanoma.[34, 57, 58, 59, 60, 61, 62] However, discontinuing anti‐CCL2 treatment would trigger recruitment of monocytes again and thus aggravate lung metastasis in mouse breast tumor.[8, 34] Additionally, inhibition of CCL5‐CCR5 axis is also an attractive solution to inhibit macrophage recruitment and suppress tumor progression in the breast tumor.[44]