STAT5B and chronic myelogenous leukemia, BCR-ABL1 positive: In hematological malignancies, such as chronic myeloid leukemia (CML) and other myeloproliferative neoplasms (MPNs), as well as in solid tumors, it has been shown that overexpression of STAT5 and deregulation of its phosphorylation contribute to disease progression and mediate resistance to tyrosine kinase inhibitors (TKIs) resistance [4,5].