In this study, three interesting observations were made with respect to PD-1/PD-L1 expression: (1) RT-DLBCL cells were more likely to express PD-1 (opposed to PD-L1, which was felt to be expressed by histiocytes in the tumor microenvironment), (2) PD-1/PD-L1 expression was associated with better responses to checkpoint blockade, (3) PD-1/PD-L1 expression was associated with ibrutinib pre-treatment. This evidence concerns the gene CD274 and diffuse large B-cell lymphoma.