Ibrutinib is a first-in-class covalent Bruton tyrosine kinase (BTK) inhibitor that blocks the B-cell receptor (BCR) signaling within chronic lymphocytic leukemia (CLL) cells, a mechanism that plays a critical role in initiating and maintaining the disease, as well as in contributing to its progression [1,2]. This evidence concerns the gene BTK and B-cell chronic lymphocytic leukemia.