The dual expression of minor and major bcr/abl chimeric mRNA in blast crisis of chronic myelogenous leukemia

T-cell blast crisis of chronic myelogenous leukemia presented with coexisting p210 and p190 BCR-ABL transcripts and t(10;11)(q11;p15)

Background

Blast transformation of chronic myelogenous leukemia (CML) to T lymphoblastic lymphoma/acute lymphoblastic leukemia (T‐LBL/ALL) is rare, and the molecular mechanism is still unclear.

Case report

A 28‐year‐old woman who developed T‐ALL with coexpressing both p210 and p190 BCR‐ABL transcripts five years after the initial diagnosis of CML in chronic phase. The proliferation of bone marrow was extremely active with blast cells over 20%. Chromosome analysis revealed t(9;22)(q34;q11) and t(10;11)(q25;p15). Flow immunophenotyping showed that blasts expressed CD4, CD7, CD11b, CD38, CD34, CD33, and cCD3.

Conclusion

It is the first T‐cell blast of CML case with coexisting p210 and p190 as well as additional chromosome translocations. Through review this case and previous reports, we will reveal that CML patients with T‐lymphocyte transformation depend on potential molecular and pathological mechanism.

Successful treatment of lymphoid blastic crisis in chronic myelogenous leukemia with the additional bcr/abl transcript using imatinib-combined chemotherapy and high-dose chemotherapy with allogeneic bone marrow stem cell transplantation

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder characterized by the presence of the Philadelphia chromosome. Although the major BCR/ABL transcript is present in majority of CML patients, the minor BCR/ABL transcript is rarely reported as an additional chromosomal abnormality related to the progression of CML. We describe the case of a 37-year-old woman who had CML and pain in the extremities. She was diagnosed with lymphoid blast crisis of CML on the basis of the following findings: presence of promyelocytes, myelocytes, and metamyelocytes in peripheral blood smear; detection of major and minor BCR/ABL transcripts by polymerase chain reaction analysis; proliferation of lymphoblastic cells with abnormal B-cell phenotype; and aberrant expression of myeloid antigens in the bone marrow. The patient underwent one course of idarubicin and cytosine arabinose therapy combined with imatinib followed by daunorubicin/cyclophosphamide plus vincristine and prednisone/L: -asparaginase (DNR/COP/L: -ASP) therapy, high-dose cytosine arabinose, and CHOP therapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone). Subsequently, the patient underwent high-dose chemotherapy (total body irradiation and cyclophosphamide) followed by allogeneic bone marrow stem cell transplantation from a human leukocyte antigen (HLA)-matched unrelated donor. After these treatments, the patient was disease-free for 19 months. Our case suggests that these treatments may be feasible, safe, and effective for the treatment of patients with blast crisis CML expressing the minor BCR/ABL transcript.

Is p190 bcr-abl rearrangement necessary for acute transformation in some p210 CML of childhood?

Chronic myeloid leukemia (CML) is a rare disease in childhood which is almost exclusively associated with bcr-abl p210 (M-bcr) rearrangements. It has been suggested that co-expression of p190 and p210 may be a pathway of CML progression in adult patients. We report two cases of pediatric patients with a diagnosis of CML who presented co-expression of the p210 and p190 transcripts during progression to the blastic phase. The present data suggest that p190 may be a secondary event in at least some cases of childhood CML, suggesting an association with progression to a blastic crisis in these patients.

Analysis of mRNA transcripts in chronic myeloid leukemia patients

The nature of BCR/ABL hybrid mRNA was analyzed by RT-PCR in cells from 33 patients (22 males, 11 females) with chronic myeloid leukemia (CML). b3a2 mRNA was found in 14 cases, whereas 13 patients had b2a2 mRNA and six had both kinds of mRNA, with a predominance of the b3a2 type. The type of mRNA present showed no significant correlation with age, hemoglobin level, number of leukocytes and platelets, percentage of blasts or basophils or the presence of splenomegaly at diagnosis. There was also no correlation with sex or duration of the chronic phase. When these results were combined with those reported by other groups, a significant association (P = 0.029) was observed for mRNA type vs. sex, with a predominance of men in the groups expressing b2a2 (2.68:1) and b3a2 (1.33:1). We conclude that the classification of patients according to mRNA type does not homogenize the clinical and hematological data within groups, where variance is large, nor does it allow a differentiation between groups.