BTK inhibitors (BTKi) have replaced several chemotherapy-based regimens in standard of care for some of the B-lineage lymphoid malignancies, especially in patients with CLL and mantle cell lymphoma (MCL) (D’Cruz and Uckun, 2013; Thompson and Burger, 2018; Bond et al., 2019; Jurczak et al., 2019; Kim, 2019). This evidence concerns the gene IBTK and cancer.