CD274 and diffuse large B-cell lymphoma: Such heterogeneity in the prevalence of PD-L1 expression might be the reason for the current disappointing low rate of clinical responses to PD-1/PD-L1 immune-checkpoints in DLBCL patients [103,104], as well as for the controversial prognostic significance of PD-L1 expression with studies reporting its association with poorer outcome [92,93,94,96,105,106], undetectable prognostic significance [107], or trends towards better event-free survival [97].