At the 2014 American Society of Hematology (ASH) Annual Meeting, Dr Simon Rule (Derriford Hospital, Plymouth, UK) discusses recent studies of the Bruton’s tyrosine kinase inhibitor, ibrutinib, in mantle cell lymphoma (MCL), including in patients with relapsed or refractory MCL who progress after bortezomib therapy and mutational analysis of these patients with primary resistance to ibrutinib, and ibrutinib in combination with rituximab.