BTK and mantle cell lymphoma: 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.