A Prognostic and Predictive Study of BCR-ABL Expression Based on Characterization of Fusion Transcripts

BCR-ABL translocation is a key hallmark of chronic myeloid leukemia (CML). The chemistry involves transcription of a novel 8.5 kb mRNA with a b3a2 and/ or b2a2 junction. Though there is an improvement in survival using the TKIs, there are causes for the treatment failures. Thus, the study focuses on the causes underlying the failed response. This study comprises BCR-ABL expression in correlation with age, gender and transcript type and disease monitoring in follow-up samples. Eighty-seven chronic phase CML patients were enrolled in the study. Out of these 24 patients were followed further. Quantitative Real time PCR was performed to assess the BCR-ABL expression followed by gel electrophoresis of PCR products. The results were expressed as CN/µg RNA. The results obtained were correlated with SPSS 16.0 software. We found three different types of the expression that includes b2a2, b3a2 and co-expression (b2a2 + b3a2). Higher incidence of b2a2 with a relatively equal incidence of co-expression was observed. The BCR-ABL expression was higher in males, in young patients and in those exhibiting co-expression of the transcripts. Greater relapse was seen in females and in older patients. The patients with co-expression of transcripts exhibited the highest expression; however these patients showed the best treatment response suggest the co-expression is the favourable parameter for CML patients. The transcript type and BCR-ABL expression are well correlated and hence can be considered as a prognostic as well as the predictive indicator considering the BCR-ABL expression for CML patients.