BTK and B-cell chronic lymphocytic leukemia: The Bruton’s tyrosine kinase (BTK) inhibitors, along with other targeted drugs such as the BCL-2 inhibitors, have fundamentally changed the treatment landscape of chronic lymphocytic leukemia (CLL) and have been transforming the treatment algorithms of other B cell malignancies (Pal Singh et al., 2018; Lucas and Woyach, 2019; Rhodes and Barrientos, 2020).