The TKI nilotinib was rationally designed to inhibit mutant forms of the BCR-ABL protein that display resistance to the TKI imatinib in patients with chronic myeloid leukemia (CML); both imatinib and nilotinib are approved for the treatment of CML. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.