BTK and leukemia: This pathway has been targeted in B-cell lymphomas and leukemias with several BCR-directed agents, such as inhibitors of Bruton's tyrosine kinase (BTK9), spleen tyrosine kinase (SYK) and phosphatidylinositol-3-kinase (PI3K) (Buggy and Elias, 2012; Dreyling et al., 2017; Liu and Mamorska-Dyga, 2017).