SIGLEC7 encodes a sialic acid-binding immunoglobulin-like lectin that functions as an inhibitory immune checkpoint receptor primarily expressed on natural killer (NK) cells and macrophages. The protein mediates sialic acid-dependent binding to cells, preferentially recognizing α-2,3- and α-2,6-linked sialic acids and disialogangliosides including GD2 and GD3 12. Upon ligand binding, SIGLEC7 recruits cytoplasmic phosphatases via SH2 domains to inhibit immune cell activation through dephosphorylation of signaling molecules 3. In cancer contexts, tumor cells exploit SIGLEC7 for immune evasion by expressing sialic acid ligands that suppress NK cell cytotoxicity and macrophage phagocytosis 14. The receptor binds to MYC-driven disialyl-T glycans, functioning as a 'don't eat me' signal that prevents cancer cell clearance 5. SIGLEC7 expression correlates with poor prognosis in multiple cancer types including prostate and pancreatic cancers, where sialylated glycans on both tumor cells and cancer-associated fibroblasts engage SIGLEC7 to promote immunosuppressive macrophage differentiation 67. Therapeutically, blocking SIGLEC7-ligand interactions enhances anti-tumor immunity, making it a promising target for cancer immunotherapy combinations 14.