The Bruton tyrosine kinase (BTK) inhibitor ibrutinib is FDA approved for relapsed and untreated CLL, relapsed mantle cell lymphoma (MCL), relapsed MZL, and Waldenström macroglobulinemia.62-67 In the phase III trial (ClinicalTrials.gov identifier: NCT01886872) of ibrutinib versus ibrutinib with rituximab or bendamustine and rituximab in 547 elderly patients with untreated CLL, the median PFS was higher with patients receiving ibrutinib alone or with rituximab. Here, BTK is linked to B-cell chronic lymphocytic leukemia.