Patterns of clonal evolution in transformed chronic myelogenous leukemia

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm that typically progresses from an indolent phase to a more aggressive acute leukemia.
• The blastic transformation phase of CML significantly worsens prognosis.

Purpose of the Study:

• To characterize the types of acute leukemias arising from blastic transformation in Chronic myelogenous leukemia (CML).
• To identify associated cytogenetic abnormalities in CML patients undergoing blastic transformation.
• To report the survival outcomes for patients in acute blast crisis.

Main Methods:

• Retrospective analysis of 75 patients with Chronic myelogenous leukemia (CML) who experienced acute blastic transformation.
• Classification of acute leukemias based on morphology and immunophenotype.
• Cytogenetic analysis to detect new abnormalities in addition to the Philadelphia chromosome (Ph).

Main Results:

• Of 75 CML patients studied, 61 developed non-lymphoid acute leukemias (54 myeloblastic, 3 promyelocytic, 1 myelomonocytic, 1 erythroblastic, 2 megakaryoblastic), and 10 developed lymphoid acute leukemias.
• Fifty-two patients exhibited new cytogenetic abnormalities, including trisomies, isochromosome 17q, and additional Philadelphia chromosome markers.
• The median survival after diagnosis of acute blast crisis was 61 days.

Conclusions:

• Blastic transformation in Chronic myelogenous leukemia (CML) frequently results in myeloid leukemias and is often accompanied by new cytogenetic aberrations.
• The development of acute blast crisis in CML portends a poor prognosis with a very short median survival.