CD4 and B-cell chronic lymphocytic leukemia: After the first year of ibrutinib treatment, the pathologically high frequencies of exhausted or chronically activated effector/memory CD4 and CD8 T cells as well as Tregs are reduced, while naive T cells are preserved and T cell receptor (TCR) repertoire diversity is significantly increased in CLL patients (Ryan et al., 2016; Yin et al., 2017; Mhibik et al., 2019; Solman et al., 2020).