Programmed Death-1 Ligands, PD-L1 and PD-L2, Show Distinctive and Restricted Patterns of Expression in Lymphoma Subtypes

The success of immunotherapy using immune checkpoint blockade in solid tumors and in relapsed/refractory classical Hodgkin lymphoma and chronic lymphocytic leukemia holds promise for targeted therapy in hematologic malignancies. Since efficacy of immunomodulatory therapy is correlated with numbers of cells that express programmed death (PD-1) ligands, we evaluated the expression of PD-L1 and PD-L2 proteins using immunohistochemistry in over 702 diagnostic lymphoma biopsies. In classical Hodgkin lymphoma, PD-L1 and PD-L2 were expressed in 82% and 41% of cases respectively, and PD-L1 but not PD-L2 expression correlated with Epstein Barr Virus in tumor cells.

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