ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: However, whilst TKI therapy has transformed the treatment of CML, 25–30% of CP-CML patients fail TKI therapy, where half of these cases have mutations in the BCR-ABL1 kinase domain (Baccarani et al., 2013), while the reason for failure in the remaining 50% of patients is unclear.