Interaction with its ligand, programmed death ligand-1 (PD-L1), expressed on transformed, stromal and myeloid-derived cells in the tumour microenvironment (TME) and tumour-draining lymph nodes, promotes tumour immune evasion—and thereby disease progression—by suppressing effector T cell proliferation, migration, and anti-tumour immune responses while enhancing immune regulatory cells1. The gene discussed is CD274; the disease is neoplasm.