AJHE2501 - CME/CMLE - Blast phase of chronic myeloid leukemia presenting as early T-cell precursor acute lymphoblastic leukemia-AJHE2501

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This article discusses the rare instances of chronic myeloid leukemia in blast phase (CML-BP) presenting with early T-cell precursor acute lymphoblastic leukemia (ETP-ALL), detailing the cases of three patients managed at M.D. Anderson Cancer Center. Chronic myeloid leukemia (CML) typically progresses through defined phases, with most blast phase transformations presenting as myeloid or precursor-B cells. However, cases involving early T-cell precursors forming acute lymphoblastic leukemia are exceptionally rare. <br /><br />The study reviews the pathological, immunophenotypic, and molecular genetic features of these patients. A key method involved fluorescence in situ hybridization (FISH), which revealed the characteristic BCR::ABL1 fusion gene present in both blast-phase cells and neutrophils, helping distinguish CML-BP from de novo Philadelphia chromosome-positive ETP-ALL.<br /><br />The three patients, all male, exhibited common features of severe leukocytosis, anemia, thrombocytopenia, and increased serum lactate dehydrogenase, with some showing splenomegaly or lymphadenopathy. Bone marrow analyses displayed high cellularity and a high percentage of blasts, which were mostly negative for myeloperoxidase. Genetic analysis confirmed typical BCR::ABL1 fusion alongside other mutations (e.g., TET2, BCOR, RUNX1, and STAG2).<br /><br />Despite receiving multi-agent chemotherapy and tyrosine kinase inhibitors, two patients died quickly post-diagnosis, underlining the aggressive nature of this condition; however, one patient who underwent a stem cell transplant survived 14 months post-transformation.<br /><br />Given its aggressive progression and poor prognosis, recognizing such CML-BP cases early allows for expedient treatment decisions, potentially benefiting from intensive therapies and stem cell transplantation. The findings stress the importance of detailed diagnosis to differentiate these cases from other lymphoid neoplasms.

Keywords

chronic myeloid leukemia

blast phase

early T-cell precursor

acute lymphoblastic leukemia

BCR::ABL1 fusion gene

fluorescence in situ hybridization

Philadelphia chromosome

tyrosine kinase inhibitors

stem cell transplantation

genetic mutations