Clinical significance of clonal evolution in chronic myeloid leukemia

Abstract

Chronic myeloid leukemia (CML) is a hematological malignancy characterized by the Philadelphia (Ph) chromosome, which is formed by a t (9;22)(q34;q11) translocation. The aberrant activation of the ABL1 tyrosine kinase is caused by the BCR::ABL1 fusion gene on the Ph chromosome, leading to significant leukemic cell proliferation. CML is typically diagnosed in the chronic phase with few clinical symptoms and progresses to a blast crisis within years. CML acquires additional genetic abnormalities on top of BCR::ABL1 fusion during clonal evolution. ASXL1 mutations are found in the chronic phase, with a frequency of approximately 20%, whereas other mutations are rare. Most blast crisis cases have additional genetic abnormalities, including frequent ASXL1 and RUNX1 mutations. Recent studies have revealed that a subset of these genetic mutations affects the sensitivity of tyrosine kinase inhibitors to leukemic cells as well as patient prognosis, indicating applications for patient stratification and individualized treatment.