The BTK inhibitor ibrutinib initially represented a new standard in the therapy of r/r CLL showing even enduring responses in CLL with TP53 mutations or del17p (133), and later it was shown that even in the therapy of CLL with mutated IGHV status the results were superior to the previous gold-standard immunochemotherapy concepts (216). Here, BTK is linked to B-cell chronic lymphocytic leukemia.