Mechanisms of Resistance to Targeted Therapies in Chronic Myeloid Leukemia.

Patients with newly diagnosed chronic myeloid leukemia (CML) usually received as first-line treatment a first- or second-generation tyrosine kinase inhibitor (TKI). Although initial responses are high, therapy fails in up to 40% of patients and initial response is lost within 2 years in approximately 25% of patients. In the last few years, intensive efforts have been spent to explain treatment failure, and different mechanisms of resistance have been identified, ranging from BCR-ABL1 kinase domain mutations to lack of adherence to therapy. In this review, we briefly summarize the clinical efficacy of approved TKIs and describe the main mechanisms of TKI resistance.