ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: To verify the prognostic significance of FLT3 signaling in BP progression, we compared critical prognostic factors of CML, including blast percentage, BCR::ABL1/ABL1 (%IS) ratio, BCR::ABL1 mutations, and overall patient survival between FLT3− and FLT3+ subgroups in BP-CML patients.