Chronic lymphocytic leukemia (CLL) is characterized by a highly abnormal immune defect in effector T cells of its microenvironment, attributed to the overexpression of PD-L1 which impairs the formation of a functional synapse with the leukemic tumor cells [101], thus limiting their ability to display an antitumor response. Here, CD274 is linked to B-cell chronic lymphocytic leukemia.