A STUDY ON THE EXPRESSION OF BCR-ABL TRANSCRIPT IN MIXED PHENOTYPE ACUTE LEUKEMIA (MPAL) CASES USING THE REVERSE TRANSCRIPTASE POLYMERASE REACTION ASSAY (RT-PCR) AND ITS CORRELATION WITH HEMATOLOGICAL REMISSION STATUS POST INITIAL INDUCTION THERAPY

Abstract

Introduction: The MPAL comprise 2-5% of all acute leukemia. The present WHO 2008 classification has separated two groups in MPAL based on t(9;22) positivity and MLL rearrangement. Aims & Objectives: The aim of the present pilot study is to note the incidence of BCR-ABL transcript in MPAL cases using the RT-PCR assay and to correlate the status with hematological remission post induction. Materials & Methods: A total of 10 MPAL cases classified on Flow-cytometry based on the current WHO 2008 criteria were enrolled. In all the cases Bone marrow or peripheral blood sample in EDTA was processed for molecular studies and the RT-PCR reaction carried out using primers specific to the t (9;22) and t(4;11) translocation. The post induction check marrow slides were also reviewed. Results: Out of the total 10 MPAL cases, 7/10 (70%) were adult and 3/10 (30%) pediatric cases. A total of 4/10 (40%) cases showed positivity for the t(9;22) transcript and none for t (4;11). Of the 4 positive cases, 3/10(30%) were adult cases and 1/10(10%) pediatric case. The BCR-ABL transcript type in adult cases was b3a2 (p210) in 2/3 (66%) and e1a2 (p190) in 1/3 (33.3%) case. The single pediatric case was positive for b3a2 transcript. Discussion & Conclusion: All the 4 positive MPAL cases presented with high TLC and low platelet count (p<0.05). The positive cases also showed hematological remission at post induction check marrow (blasts<5%). This could partly be explained due to good response to the imatinib added to the treatment protocol.