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CD47 (cluster of differentiation 47; integrin-associated protein, IAP)
is a widely expressed transmembrane glycoprotein that regulates cell adhesion,
migration and immune recognition. On tumour cells, CD47 binds
SIRPα on macrophages and other myeloid cells, activating an
inhibitory signal that suppresses phagocytosis and functions as a
“don't eat me” immune checkpoint. CD47 is frequently
overexpressed in many hematologic and solid malignancies and can promote immune
evasion, tumour-cell survival, metastatic progression and resistance to therapy.
Blocking the CD47–SIRPα interaction can restore macrophage-mediated
phagocytosis and enhance antigen presentation and downstream antitumour immune
responses. The typical cancer-associated direction is therefore
up, while the desired anticancer modulation is generally
down, receptor blockade or disruption of CD47–SIRPα
signalling.
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