As a unique small-molecule inhibitor selectively binding to BTK in the context of a complex proteome to inhibit B cell activation [86], ibrutinib has succeeded in treating some mature B-cell neoplasms, including chronic lymphocytic leukemia (CLL) [11], mantle cell lymphoma [12], and Waldenström macroglobulinemia [87], as well as some non-GCB-type DLBCLs [88]. This evidence concerns the gene BTK and B-cell chronic lymphocytic leukemia.