An Automated Cartridge-Based Microfluidic System for Real-Time Quantification of BCR::ABL1 Transcripts in Chronic Myeloid Leukemia: An Italian Experience

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder caused by the <i>BCR::ABL1</i> fusion gene, resulting from a reciprocal translocation between chromosomes 22 and 9. Quantification of <i>BCR::ABL1</i> transcript levels in peripheral blood by RT-qPCR represents the gold standard for molecular response (MR) monitoring, providing essential clinical information on treatment efficacy. Xpert^® BCR-ABL Ultra is a fully automated in vitro diagnostic test that quantitatively detects e13a2 and e14a2 <i>BCR::ABL1</i> transcripts using a single-use cartridge that integrates RNA extraction, cDNA synthesis, nested real-time PCR, and signal detection within a rapid, closed, and user-friendly system. In this study, we evaluated Xpert^® BCR-ABL Ultra as an alternative to validated systems currently used by four highly specialized Italian laboratories affiliated with the Italian national laboratory network for CML. A total of 129 peripheral blood samples from CML patients at various disease stages, along with two external quality control materials, were analyzed. We assessed the test's repeatability, specificity, and stability. Concordance of <i>BCR::ABL1</i>%IS values generated by the different methods was evaluated using EUTOS criteria and Bland-Altman analysis. Finally, MR value concordance was analyzed based on European LeukemiaNet recommendations or calculated using the formula 2 - log₁₀(<i>BCR::ABL1</i>%IS). Xpert^® BCR-ABL Ultra demonstrated high repeatability and stability. The <i>BCR::ABL1</i>%IS values obtained with this assay showed strong concordance with those generated by local reference methods, and MR classifications were consistent across platforms. These findings confirm the robustness, accuracy, and efficiency of the Xpert^® BCR-ABL Ultra assay, supporting its use as a reliable alternative to currently validated systems for the routine clinical monitoring of CML patients.