Goodbye to accelerated phase of chronic myeloid leukaemia

Abstract Whether there is really a distinct accelerated phase (AP) at diagnosis in chronic myeloid leukemia (CML) in the context of tyrosine kinase-inhibitor (TKI)-therapy and whether co-variates identified as characterizing AP are simply adverse co-variates for outcomes, we studied 2,122 consecutive subjects in chronic phase (CP, n = 1,837) or AP (n = 285) according to the European LeukemiaNet (ELN) classification. AP subjects with increased basophils only had similar transformation-free survival (TFS) and survival compared with CP subjects in ELTS intermediate-risk. AP subjects with increased blasts only had worse TFS but similar survival compared with CP subjects in the ELTS high-risk; AP subjects with decreased platelets only, similar TFS but worse survival. Proportions of CP and AP subjects meeting the 2020 ELN TKI-response milestones were similar. However, worse outcomes were only seen in AP subjects failing to meet ELN milestones. Findings were similar using the 2022 International Consensus Classification (ICC) criteria replacing decreased platelets with additional cytogenetic abnormalities. Our data support the 2022 WHO classification of CML eliminating AP. We suggest adding a very high-risk cohort to the ELTS score including people with increased blasts or decreased platelets and dividing CML into 2 phases: CP and acute phase.