PDCD1 and B-cell chronic lymphocytic leukemia: Similarly, a study using the Eμ-TCL1 adoptive transfer mouse model of chronic lymphocytic leukemia (CLL), observed that combination of ibrutinib with blocking antibodies targeting the PD-1 or PD-L1 axis in vivo improved CD8 T cell effector function and control of lymphocyte proliferation (54).