In this 5th version of the European LeukemiaNet guidance for adult patients, there are important changes in several areas of management based on evidence available since 2020, including the World Health Organisation's reclassification of CML as a biphasic disease. Previous advice to switch the tyrosine kinase inhibitor (TKI) on failure of molecular milestones, is modified to better account for individual patient circumstances. Our recommendations are summarized in tables designed to be read in conjunction with the text which offers justification and additional advice. We describe decision-making for first-line treatment, both in available drugs and their initial dosing. Similarly we elaborate on dose reduction rather than drug switching to manage toxicities and discuss treatment sequencing. Data have matured for the outcome of treatment discontinuation and for management of parenting for both men and women. We acknowledge that most patients will remain on treatment for many years and emphasize the needs to minimize side effects, manage co-morbidities and optimize quality of life. Recent advances in allogeneic stem cell transplantation have broadened access to alternative donors, and lessened limitations of age and co-morbidities such that transplant remains a valuable option for patients for whom long-term disease control is not achieved through TKI therapy.

• MeSH
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive * therapy   drug therapy   diagnosis   MeSH
• Protein Kinase Inhibitors * therapeutic use   MeSH
• Humans MeSH
• Disease Management MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Practice Guideline MeSH
• Geographicals
• Europe MeSH
• Names of Substances
• Protein Kinase Inhibitors * MeSH

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

Several studies have reported that chronic myeloid leukaemia (CML) patients expressing e14a2 BCR::ABL1 have a faster molecular response to therapy compared to patients expressing e13a2. To explore the reason for this difference we undertook a detailed technical comparison of the commonly used Europe Against Cancer (EAC) BCR::ABL1 reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assay in European Treatment and Outcome Study (EUTOS) reference laboratories (n = 10). We found the amplification ratio of the e13a2 amplicon was 38% greater than e14a2 (p = 0.015), and the amplification efficiency was 2% greater (P = 0.17). This subtle difference led to measurable transcript-type dependent variation in estimates of residual disease which could be corrected by (i) taking the qPCR amplification efficiency into account, (ii) using alternative RT-qPCR approaches or (iii) droplet digital PCR (ddPCR), a technique which is relatively insensitive to differences in amplification kinetics. In CML patients, higher levels of BCR::ABL1/GUSB were identified at diagnosis for patients expressing e13a2 (n = 67) compared to e14a2 (n = 78) when analysed by RT-qPCR (P = 0.0005) but not ddPCR (P = 0.5). These data indicate that widely used RT-qPCR assays result in subtly different estimates of disease depending on BCR::ABL1 transcript type; these differences are small but may need to be considered for optimal patient management.

• MeSH
• Fusion Proteins, bcr-abl * genetics   MeSH
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive * diagnosis   drug therapy   genetics   MeSH
• Imatinib Mesylate MeSH
• Real-Time Polymerase Chain Reaction MeSH
• Humans MeSH
• Neoplasm, Residual genetics   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
• Imatinib Mesylate MeSH