From the laboratory perspective, effective management of patients with chronic myeloid leukemia (CML) requires accurate diagnosis, assessment of prognostic markers, sequential assessment of levels of residual disease and investigation of possible reasons for resistance, relapse or progression. Our scientific and clinical knowledge underpinning these requirements continues to evolve, as do laboratory methods and technologies. The European LeukemiaNet convened an expert panel to critically consider the current status of genetic laboratory approaches to help diagnose and manage CML patients. Our recommendations focus on current best practice and highlight the strengths and pitfalls of commonly used laboratory tests.

• MeSH
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive * diagnosis   genetics   therapy   MeSH
• Protein Kinase Inhibitors * MeSH
• Humans MeSH
• Recurrence MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Protein Kinase Inhibitors * MeSH

One of the indications for BCR::ABL1 mutation testing in chronic myeloid leukemia (CML) is when tyrosine kinase inhibitor therapy (TKI) needs to be changed for unsatisfactory response. In this study, we evaluated a droplet digital PCR (ddPCR)-based multiplex strategy for the detection and quantitation of transcripts harbouring mutations conferring resistance to second-generation TKIs (2GTKIs). Parallel quantitation of e13a2, e14a2 and e1a2 BCR::ABL1 fusion transcripts enables to express results as percentage of mutation positive- over total BCR::ABL1 transcripts. We determined the limit of blank in 60 mutation-negative samples. Accuracy was demonstrated by further analysis of 48 samples already studied by next generation sequencing (NGS). Mutations could be called down to 0.5% and across 3-logs of BCR::ABL1 levels. Retrospective review of BCR::ABL1 NGS results in 513 consecutive CML patients with non-optimal response to first- or second-line TKI therapy suggested that a ddPCR-based approach targeted against 2GTKI-resistant mutations would score samples as mutation-negative in 22% of patients with warning response to imatinib but only in 6% of patients with warning response to 2GTKIs. We conclude ddPCR represents an attractive method for easy, accurate and rapid screening for 2GTKI-resistant mutations impacting on TKI selection, although ddPCR cannot identify compound mutations.

• MeSH
• Fusion Proteins, bcr-abl * MeSH
• Drug Resistance, Neoplasm MeSH
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive * MeSH
• Protein Kinase Inhibitors MeSH
• Humans MeSH
• Mutation MeSH
• Polymerase Chain Reaction MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Fusion Proteins, bcr-abl * MeSH
• Protein Kinase Inhibitors MeSH