BTK and B-cell chronic lymphocytic leukemia: To date BTK overexpression/hyperactivation has been shown in several B cell-derived malignancies such as chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), mantle cell lymphoma (MCL), Waldenström’s Macroglobulinemia (WM), Marginal Zone Lymphoma (MZL), in the most common form of non-Hodgkin lymphoma i.e., activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL), and in multiple myeloma (MM) (3).