CD274 and neoplasm: Antibody blockade of PD-L1 in the context of PD-L1-deficient tumours (Fig. 5b) mimicked the effect seen in the combined tumour/host PD-L1-deficient setting, confirming that PD-L1, more so than PD-L2, was a main driver of immune suppression in the outgrowing PD-L1-deficient tumours.