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The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

BCR::ABL1-targeting tyrosine kinase inhibitors (TKIs) dominate the treatment of chronic myeloid leukemia (CML) over the past decades. In this study, we reported an unexpected role of neddylation inhibitors in desensitizing the therapeutic efficacy of BCR::ABL1-targeting TKIs in CML. Unlike their function in reducing drug resistance in many solid tumors, we revealed that neddylation inhibitors counteracted the cytotoxicity of TKIs against CML cells, both in cellular experiments and in animal model. Conversely, neddylation agonist sensitized the function of TKIs. RNA sequencing data revealed that neddylation inhibitor reversed the transcriptomic changes induced by TKI. Co-immunoprecipitation (co-IP) assay identified ABL1 kinase domain as a novel substrate for neddylation. Furthermore, an artificial intelligence (AI) 3-Dimensional spatial structure binding technology was employed to predict the impact of neddylation on the structure of ABL1 kinase domain. Finally, we provided potential evidence showing that TKI therapy decreased the expression of neddylation enzymes in the bone marrow of CML patients. Hence, our study offers new insights into the post-translational modification (PTM)-mediated drug resistance, and highlights the potential clinical benefits of neddylation agonists in improving the responsiveness of BCR::ABL1 TKIs in CML.

The selective allosteric ABL1 inhibitor ABL001 (asciminib) represents a new inhibitory mechanism for BCR–ABL1-driven malignancies, and its efficacy and evolving mechanisms of resistance do not overlap with those of other BCR–ABL1 kinase inhibitors. Dual targeting of gene fusion Current inhibitors targeting the BCR–ABL1 mutation have saved many lives but their application is limited by resistance-driving mutations. Here, the authors report the characterization of ABL001, a new allosteric ABL inhibitor. The compound represents a new inhibitory enzymatic mechanism for BCR–ABL-driven malignancies and could be applied for cases of resistance. The authors note that its efficacy and evolving mechanisms of resistance do not overlap with other BCR–ABL kinase inhibitors. Chronic myeloid leukaemia (CML) is driven by the activity of the BCR–ABL1 fusion oncoprotein. ABL1 kinase inhibitors have improved the clinical outcomes for patients with CML, with over 80% of patients treated with imatinib surviving for more than 10 years 1 . Second-generation ABL1 kinase inhibitors induce more potent molecular responses in both previously untreated and imatinib-resistant patients with CML 2 . Studies in patients with chronic-phase CML have shown that around 50% of patients who achieve and maintain undetectable BCR–ABL1 transcript levels for at least 2 years remain disease-free after the withdrawal of treatment 3 , 4 . Here we characterize ABL001 (asciminib), a potent and selective allosteric ABL1 inhibitor that is undergoing clinical development testing in patients with CML and Philadelphia chromosome-positive (Ph + ) acute lymphoblastic leukaemia. In contrast to catalytic-site ABL1 kinase inhibitors, ABL001 binds to the myristoyl pocket of ABL1 and induces the formation of an inactive kinase conformation. ABL001 and second-generation catalytic inhibitors have similar cellular potencies but distinct patterns of resistance mutations, with genetic barcoding studies revealing pre-existing clonal populations with no shared resistance between ABL001 and the catalytic inhibitor nilotinib. Consistent with this profile, acquired resistance was observed with single-agent therapy in mice; however, the combination of ABL001 and nilotinib led to complete disease control and eradicated CML xenograft tumours without recurrence after the cessation of treatment.

A large ex vivo screen of approved and investigational anti-cancer drugs in primary cells derived from CML and ALL patients identifies axitinib, a VEGFR inhibitor approved for the treatment of kidney cancer, as a potent inhibitor of BCR–ABL1(T315I) with unique binding interactions that overcome the gatekeeper resistance mutation, highlighting the potential of repurposing existing drugs for additional cancer types. Anti-leukaemia potential of axitinib Many chronic myeloid leukaemias (CMLs) and acute lymphoblastic leukaemias (ALLs) are driven by the BCR-ABL fusion gene. Targeting BCR-ABL with selective kinase inhibitors has revolutionized CML treatment, but patients often develop resistance, often due to secondary mutations in BCR-ABL . In this large-scale screen of approved and investigational anti-cancer drugs in primary cells from CML and ALL patients, Krister Wennerberg and colleagues identify axitinib, a multi-kinase inhibitor approved for the treatment of kidney cancer, as having activity in primary patient-derived CML and ALL cells, including cells with secondary resistance mutations. In one CML patient, for whom all other treatment options had been exhausted, axitinib induced reduced levels of circulating BCR - ABL transcripts. These preliminary clinical findings highlight the potential of repurposing existing drugs for additional cancer types. The BCR-ABL1 fusion gene is a driver oncogene in chronic myeloid leukaemia and 30–50% of cases of adult acute lymphoblastic leukaemia 1 . Introduction of ABL1 kinase inhibitors (for example, imatinib) has markedly improved patient survival 2 , but acquired drug resistance remains a challenge 3 , 4 , 5 . Point mutations in the ABL1 kinase domain weaken inhibitor binding 6 and represent the most common clinical resistance mechanism. The BCR–ABL1 kinase domain gatekeeper mutation Thr315Ile (T315I) confers resistance to all approved ABL1 inhibitors except ponatinib 7 , 8 , which has toxicity limitations. Here we combine comprehensive drug sensitivity and resistance profiling of patient cells ex vivo with structural analysis to establish the VEGFR tyrosine kinase inhibitor axitinib as a selective and effective inhibitor for T315I-mutant BCR–ABL1-driven leukaemia. Axitinib potently inhibited BCR–ABL1(T315I), at both biochemical and cellular levels, by binding to the active form of ABL1(T315I) in a mutation-selective binding mode. These findings suggest that the T315I mutation shifts the conformational equilibrium of the kinase in favour of an active (DFG-in) A-loop conformation, which has more optimal binding interactions with axitinib. Treatment of a T315I chronic myeloid leukaemia patient with axitinib resulted in a rapid reduction of T315I-positive cells from bone marrow. Taken together, our findings demonstrate an unexpected opportunity to repurpose axitinib, an anti-angiogenic drug approved for renal cancer, as an inhibitor for ABL1 gatekeeper mutant drug-resistant leukaemia patients. This study shows that wild-type proteins do not always sample the conformations available to disease-relevant mutant proteins and that comprehensive drug testing of patient-derived cells can identify unpredictable, clinically significant drug-repositioning opportunities.

Nilotinib has shown greater efficacy than imatinib in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukaemia (CML) in chronic phase after a minimum follow-up of 12 months. We present data from the Evaluating Nilotinib Efficacy and Safety in clinical Trials–newly diagnosed patients (ENESTnd) study after a minimum follow-up of 24 months. ENESTnd was a phase 3, multicentre, open-label, randomised study. Adult patients were eligible if they had been diagnosed with chronic phase, Philadelphia chromosome-positive CML within the previous 6 months. Patients were randomly assigned (1:1:1) to receive nilotinib 300 mg twice a day, nilotinib 400 mg twice a day, or imatinib 400 mg once a day, all administered orally, by use of a computer-generated randomisation schedule, using permuted blocks, and stratified according to Sokal score. Efficacy results are reported for the intention-to-treat population. The primary endpoint was major molecular response at 12 months, defined as BCR–ABL transcript levels on the International Scale (BCR–ABL IS) of 0·1% or less by real-time quantitative PCR in peripheral blood. This study is registered with ClinicalTrials.gov, number NCT00471497. 282 patients were randomly assigned to receive nilotinib 300 mg twice daily, 281 to receive nilotinib 400 mg twice daily, and 283 to receive imatinib. By 24 months, significantly more patients had a major molecular response with nilotinib than with imatinib (201 [71%] with nilotinib 300 mg twice daily, 187 [67%] with nilotinib 400 mg twice daily, and 124 [44%] with imatinib; p<0·0001 for both comparisons). Significantly more patients in the nilotinib groups achieved a complete molecular response (defined as a reduction of BCR–ABL IS levels to ≤0·0032%) at any time than did those in the imatinib group (74 [26%] with nilotinib 300 mg twice daily, 59 [21%] with nilotinib 400 mg twice daily, and 29 [10%] with imatinib; p<0·0001 for nilotinib 300 mg twice daily vs imatinib, p=0·0004 for nilotinib 400 mg twice daily vs imatinib). There were fewer progressions to accelerated or blast phase on treatment, including clonal evolution, in the nilotinib groups than in the imatinib group (two with nilotinib 300 mg twice daily, five with nilotinib 400 mg twice daily, and 17 with imatinib; p=0·0003 for nilotinib 300 mg twice daily vs imatinib, p=0·0089 for nilotinib 400 mg twice daily vs imatinib). At 24 months, survival was comparable in all treatment groups, but fewer CML-related deaths had occurred in both the nilotinib groups than in the imatinib group (five with nilotinib 300 mg twice daily, three with nilotinib 400 mg twice daily, and ten with imatinib). Overall, the only grade 3 or 4 non-haematological adverse events that occurred in at least 2·5% of patients were headache (eight [3%] with nilotinib 300 mg twice daily, four [1%] with nilotinib 400 mg twice daily, and two [<1%] with imatinib) and rash (two [<1%], seven [3%], and five [2%], respectively). Grade 3 or 4 neutropenia was more common with imatinib than with either dose of nilotinib (33 [12%] with nilotinib 300 mg twice daily, 30 [11%] with nilotinib 400 mg twice daily, and 59 [21%] with imatinib). Serious adverse events were reported in eight additional patients in the second year of the study (four with nilotinib 300 mg twice daily, three with nilotinib 400 mg twice daily, and one with imatinib). Nilotinib continues to show better efficacy than imatinib for the treatment of patients with newly diagnosed CML in chronic phase. These results support nilotinib as a first-line treatment option for patients with newly diagnosed disease. Novartis.

Asciminib, an agent that targets the myristoyl pocket of BCR::ABL, was compared with imatinib and with imatinib plus second-generation tyrosine kinase inhibitors. Outcomes were better with asciminib in both comparisons.

Chronic myeloid leukemia (CML) is a malignant clonal disease involving hematopoietic stem cells that is characterized by myeloid cell proliferation in bone marrow and peripheral blood, and the presence of the Philadelphia (Ph) chromosome with BCR-ABL fusion gene. Treatment of CML has dramatically improved since the advent of tyrosine kinase inhibitors (TKI). However, there are a small subset of CML patients who develop resistance to TKI. Mutations in the ABL kinase domain (KD) are currently recognized as the leading cause of TKI resistance in CML. In this review, we discuss the concept of resistance and summarize recent advances exploring the mechanisms underlying CML resistance. Overcoming TKI resistance appears to be the most successful approach to reduce the burden of leukemia and enhance cures for CML. Advances in new strategies to combat drug resistance may rapidly change the management of TKI-resistant CML and expand the prospects for available therapies.

Chronic myeloid leukemia (CML) is characterized by the presence of the BCR-ABL1 fusion gene, which encodes a constitutive active tyrosine kinase considered to be the pathogenic driver capable of initiating and maintaining the disease. Despite the remarkable efficacy of tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1, some patients may not respond (primary resistance) or may relapse after an initial response (secondary resistance). In a small proportion of cases, development of resistance is accompanied or shortly followed by progression from chronic to blastic phase (BP), characterized by a dismal prognosis. Evolution from CP into BP is a multifactorial and probably multistep phenomenon. Increase in BCR-ABL1 transcript levels is thought to promote the onset of secondary chromosomal or genetic defects, induce differentiation arrest, perturb RNA transcription, editing and translation that together with epigenetic and metabolic changes may ultimately lead to the expansion of highly proliferating, differentiation-arrested malignant cells. A multitude of studies over the past two decades have investigated the mechanisms underlying the closely intertwined phenomena of drug resistance and disease progression. Here, we provide an update on what is currently known on the mechanisms underlying progression and present the latest acquisitions on BCR-ABL1-independent resistance and leukemia stem cell persistence.

The BCR::ABL1 oncogene plays a crucial role in the development of chronic myeloid leukemia (CML). Previous studies have investigated the involvement of mitochondrial dynamics in various cancers, revealing potential therapeutic strategies. However, the impact of BCR::ABL1 on mitochondrial dynamics remains unclear. In this study, we demonstrated that BCR::ABL1 is sufficient to induce excessive mitochondrial fragmentation by activating dynamin‐related protein (DRP)1 through the mitogen‐activated protein kinase (MAPK) pathway. Leukocytes obtained from patients with CML and the BCR::ABL1‐positive cell lines exhibited increased mitochondrial fragmentation compared to leukocytes obtained from healthy donors and BCR::ABL1‐negative cells. Furthermore, the analysis of BCR::ABL1‐transduced cells showed increased phosphorylation of DRP1 at serine 616 and extracellular signal‐regulated kinase (ERK) 1/2. Moreover, the inhibition of DRP1 and upstream mitogen‐activated extracellular signal‐regulated kinase (MEK) 1/2 suppressed mitochondrial fragmentation. Strikingly, DRP1 inhibition effectively reduced the viability of BCR::ABL1‐positive cells and induced necrotic cell death. Additionally, a label‐free artificial intelligence‐driven flow cytometry successfully identified not only the BCR::ABL1‐transduced cells but also peripheral leukocytes from CML patients by assessing mitochondrial morphological alterations. These findings suggested the crucial role of BCR::ABL1‐induced mitochondrial fragmentation in driving BCR::ABL1‐positive cell proliferation, and the potential use of mitochondrial morphological alterations as a clinical biomarker for the label‐free detection of CML cells. BCR::ABL1 promotes mitochondrial fragmentation by activating DRP1 via the MAPK pathway. These mitochondrial alterations may enhance cell proliferation, making them as promising therapeutic targets for BCR::ABL1‐positive leukemia and potential early CML diagnosis biomarkers through AI‐driven flow cytometry.

Ponatinib was developed to overcome resistance to the tyrosine kinase inhibitors used to treat leukemias that are positive for the Philadelphia chromosome. In a phase 1 study, ponatinib was associated with dramatic antitumor effects, with pancreatitis as a dose-limiting toxicity. The fusion protein product of the Philadelphia chromosome (Ph), BCR-ABL, is a constitutively active tyrosine kinase that gives rise to chronic myeloid leukemia (CML) and a subset of acute lymphoblastic leukemia (Ph-positive ALL). 1 , 2 Three tyrosine kinase inhibitors targeting the BCR-ABL protein (imatinib, nilotinib, and dasatinib) have been approved for the treatment of patients with newly diagnosed chronic-phase CML. 3 – 5 Resistance to tyrosine kinase inhibitors is the major reason for the failure of therapy in patients with Ph-positive disease. Primary or secondary resistance to imatinib occurs in approximately 20 to 30% of patients with newly diagnosed chronic-phase CML. 3 , 6 Second-generation . . .