Ibrutinib, a first-in-class Bruton's tyrosine kinase (BTK) irreversible inhibitor, also targeting other kinases such as ITK [1] and EGFR [2], is changing treatment paradigms of some chronic lymphoproliferative disorders such as chronic lymphocytic leukemia (CLL), mantle cell lymphoma and Waldenström macroglobulinemia [3]. The gene discussed is BTK; the disease is mantle cell lymphoma.