• Overview of CML: epidemiology, pathophysiology, diagnosis, and WHO classification updates. • Focus on TKI resistance: PI3K/AKT, MAPK, JAK/STAT, SRC/AKT pathways. • Insights into genetic mutations driving resistance, advancing clinical strategies for CML.

Background/Objectives: Chronic myeloid leukemia (CML) is a hematopoietic stem cell malignancy initiated by the BCR::ABL1 oncoprotein. Although tyrosine kinase inhibitors (TKIs) have revolutionized CML therapy, resistance remains a major clinical challenge. Emerging evidence suggests that metabolic reprogramming contributes to TKI resistance, yet its relationship with oxidative stress and autophagy remains poorly characterized. Methods: Metabolic profiles, redox-related parameters, and autophagy markers were assessed in parental K562, imatinib-sensitive K562-S, and imatinib-resistant K562-R cells. Metabolic activity was first assessed via the MTT assay to determine the half-maximal inhibitory concentration (IC₅₀) for each line, which was subsequently used as the treatment dose. Glycolytic and mitochondrial functions were profiled via Seahorse extracellular flux analysis under basal conditions. Oxidative stress was assessed via reactive oxygen species (ROS) and nitric oxide (NO) levels, and the levels of autophagy markers (p62 and LC3-I/II) were measured via Western blotting. Results: Imatinib reduced metabolic activity in K562 and K562-S cells (IC₅₀ = 0.445 and 0.137 µM, respectively), whereas K562-R cells retained high metabolic activity across the tested range (0.1–1 µM), which was consistent with a resistant phenotype. Compared with parental K562 cells, both K562-S and K562-R cells presented reduced glycolytic activity. K562-S cells displayed greater basal respiration than K562-R cells, which presented reduced basal respiration and proton leakage but preserved spare respiratory capacity, indicating a distinct mitochondrial respiratory phenotype. Imatinib increased ROS in K562 and K562-S cells but not in K562-R cells, whereas NO increased in all three lines. Autophagy-related alterations occurred in K562 and K562-S cells, while K562-R cells presented minimal changes. Conclusions: Imatinib resistance involves distinct metabolic and autophagic adaptations across K562-derived cell lines. These pathways may represent potential therapeutic targets warranting further investigation to overcome TKI resistance in CML.

Chronic myeloid leukemia (CML) is driven by the constitutive tyrosine kinase activity of the BCR::ABL1 fusion protein and is effectively treated with tyrosine kinase inhibitors (TKIs). However, therapeutic resistance and the persistence of leukemic stem cells (LSCs) remain important clinical challenges. TKI resistance cannot be explained solely by BCR::ABL1-dependent mechanisms and involves a complex interplay between signaling, metabolic, redox, and autophagic adaptations. In this review, we integrate current knowledge on BCR::ABL1-dependent and BCR::ABL1-independent resistance mechanisms, with particular emphasis on metabolic reprogramming in CML LSCs and TKI-resistant leukemic cells. Available evidence indicates that primitive CML populations can exhibit enhanced mitochondrial oxidative metabolism, whereas TKI-resistant and persistent leukemic populations may engage glycolysis, the pentose phosphate pathway, fatty acid oxidation, and amino acid metabolism to different extents. Rather than representing mutually exclusive metabolic states, oxidative and glycolytic programs may coexist and vary according to cellular differentiation, microenvironmental conditions, and therapeutic pressure. These metabolic adaptations are interconnected with major signaling pathways, including PI3K/AKT/mTOR, JAK/STAT, Wnt/β-catenin, and Hedgehog signaling, as well as with redox regulation and autophagy. Preclinical studies suggest that combining TKIs with metabolism- or autophagy-directed interventions may help exploit vulnerabilities associated with leukemic persistence. However, the heterogeneity of metabolic phenotypes, potential toxicity to normal hematopoietic cells, and limited clinical validation of candidate metabolic biomarkers currently constrain their therapeutic translation. Further studies are therefore required to determine which metabolic dependencies are clinically actionable and whether biomarker-guided strategies can improve the targeting of persistent CML cells.

Chronic myeloid leukaemia (CML) is driven by the constitutively active BCR::ABL1 fusion tyrosine kinase. Although tyrosine kinase inhibitors (TKIs) have dramatically improved patient survival, therapeutic resistance and the persistence of leukemic stem cells (LSCs) remain major barriers to durable disease control and treatment-free remission. This review examines BCR::ABL1-dependent and independent mechanisms of TKI resistance, with particular emphasis on metabolic reprogramming as an adaptive component of CML persistence. Accumulating evidence indicates that resistant and primitive CML populations do not conform to a single metabolic phenotype. Instead, therapeutic pressure selects and reshapes heterogeneous cell states capable of dynamically redistributing energy production and substrate utilization among glycolysis, oxidative phosphorylation, fatty acid oxidation, glutamine metabolism, and other amino acid pathways. This metabolic plasticity is further influenced by mitochondrial fitness, redox regulation, the bone marrow microenvironment, epigenetic-metabolic interactions, and immunometabolic mechanisms. Single-cell and spatial approaches are beginning to resolve the cellular heterogeneity underlying these adaptive states and their association with treatment response. Metabolic vulnerabilities therefore provide a rationale for combining BCR::ABL1 inhibition, including asciminib, with strategies targeting mitochondrial metabolism, glycolysis, fatty acid oxidation, glutamine utilization, autophagy, or hypoxia-responsive pathways. However, most such combinations remain preclinical, highlighting the need for biomarker-guided patient stratification and prospective clinical validation.