BTK and B-cell chronic lymphocytic leukemia: For example, Bruton tyrosine kinase (BTK)-inhibitors such as ibrutinib and acalabrutinib improve CLL therapy, reducing the impact of adverse prognostic covariates such as fludarabine resistance, del (11q), unmutated IGHV and TP53 mutation/abnormality and purine-analogue resistance [40,41,42,43,44,45].