Fully Automated GeneXpert BCR-ABL1 Assay versus Standard Nonautomated BCR-ABL1 Real-Time Reverse Transcription-Polymerase Chain Reaction Quantitation: A Study from Tertiary Care Institute in India.

Background: Molecular monitoring of chronic myeloid leukemia (CML) patients receiving tyrosine kinase inhibitors at various time points after diagnosis is indispensable for therapeutic stratification. Thus, standardization and reproducibility of these tests to an international scale are of paramount importance. Standard TRUPCR BCR-ABL1 by quantitative real-time reverse transcription-polymerase chain reaction and Xpert BCR-ABL Ultra performed on the Cepheid GeneXpert^® Instrument Systems (GeneXpert) were used to perform molecular monitoring in CML patients.

Materials and methods: Twenty-six samples (6 diagnostic and 20 monitoring samples) were tested on both platforms, and the BCR-ABL1 transcript ratio was compared. Kappa statistic was applied to calculate the agreement between the two tests, and Chi-square test was used to evaluate the difference in proportions in the two groups. The costs between the two tests were also compared, however, no statistical analysis was done for the same.

Results: All six diagnostic samples were detected by TRUPCR, but only four could be detected by GeneXpert. One of these was a minor BCR-ABL1 transcript (p190) which cannot be detected by GeneXpert. Among the 20 monitoring samples, there was moderate agreement between the two tests, with a P = 0.01. The cost of TRUPCR was significantly less compared to GeneXpert.

Conclusion: Standard BCR-ABL1 estimation by TRUPCR is superior and much more cost-effective than GeneXpert. GeneXpert inspite being an easy-to-use, fully automated platform lacks the benefit of customization with a high cost making the standard reverse transcription-polymerase chain reaction techniques more feasible and usable for molecular monitoring in CML patients.