Prognostic Implication of BCR-ABL Fusion Transcript Variants in Chronic Myeloid Leukemia (CML) Treated with Imatinib. A First of Its Kind Study on CML Patients of Kashmir

BACKGROUND: The prognostic significance of the common BCR-ABL transcripts like e13a2 (b2a2) and e14a2 (b3a2) in Chronic myeloid leukemia (CML) has been reported from patients treated with different tyrosine kinase inhibitors but its impact on clinical response and overall survival remains still unexplored. The aim of this study was to evaluate the prognostic significance of different transcript types in a cohort of CML patients treated with imatinib. METHODS: A total 42 confirmed cases of Chronic Myeloid Leukemia (CML) patients were recruited into our cohort study and a multiplex Reverse Transcriptase-Polymerase Chain Reaction technique (RT-PCR) was used to detect 3 main transcript types ‘e1a2’, ‘e13a2’, and ‘e14a2’ found in CML. RESULTS: Only two types of transcripts e13a2 (b2a2) and e14a2 (b3a2) were detected in our CML patients and none had the e1a2 type. All the patients were RT-PCR positive for either e13a2 or e14a2 fusion transcript demonstrating 100% concordance with their Ph+ve cytogenetic status at baseline. TLC count (range of 201-600x10(3)/µl) and platelet count (range of 201-900x10(3)/µl) at baseline were found to be associated more with the e14a2 (b3a2) than the e13a2 (b2a2) transcript type (p-value: 0.001). The two transcripts found did not relate significantly towards sex, age-group or indicated spleen size ranges as well as percentage ranges of blast cells. CONCLUSION: We conclude that there is no overall prognostic implication of either the e13a2 or the e14a2 transcript type across the spectrum of indicated clinical parameters evaluated. Even the overall survival analysis of the two transcript types revealed no prognostic association whatsoever.