PD-L1 blockade: rejuvenating T cells in CLL

In this issue of Blood, there are 2 articles by McClanahan et al describing T-cell defects in murine chronic lymphocytic leukemia (CLL) in the context of aging which show that therapeutic targeting of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) signaling prevents immune dysfunction and leukemia development.(1,2)