CCR2 and neoplasm: Axes such as CCL2/CCR2 and CCL5/CCR5 regulate tumor-associated monocyte/macrophage (TAM) and regulatory T-cell (Treg) trafficking, often fostering immunosuppressive niches that hinder cytotoxic lymphocyte (CTL) function, whereas CXCL9/CXCL10 support CTL recruitment and are associated with benefit from PD-1/PD-L1 blockade [45,46,47,48] (Table 4).