Ibrutinib is an inhibitor of Bruton’s tyrosine kinase (BTKi), a nonreceptor tyrosine kinase critical for BCR signal transduction, which has been approved for the treatment of relapsed/refractory CLL, and also in those harboring del (17)/TP53 mutations in the first-line setting. This evidence concerns the gene BCR and B-cell chronic lymphocytic leukemia.