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ENL, identified in a genome-scale loss-of-function screen as a crucial requirement for proliferation of acute leukaemia, is required for leukaemic gene expression, and its YEATS chromatin-reader domain is essential for leukaemic growth. Gene control in acute leukaemia Recurrent chromosomal translocations involving the mixed lineage leukaemia (MLL) gene give rise to acute myeloid leukaemia (AML). Here, James Bradner and colleagues perform a genome-scale loss-of-function screen using CRISPR–Cas9 technology in MLL-AF4 AML cells. They find that the ENL gene is critical for cell proliferation and use a chemical genetic strategy of targeted protein degradation to show that loss of ENL suppresses transcriptional activation as well as leukaemic growth. ENL-dependent leukaemic growth depends on its YEATS chromatin reader domain, indicating that competitive antagonists of the YEATS domain could be potential therapeutics for AML. A related paper in this week's issue of Nature from Xiaobing Shi and colleagues provides insights into the function of the ENL YEATS domain in recognizing acetylated histones. Recurrent chromosomal translocations producing a chimaeric MLL oncogene give rise to a highly aggressive acute leukaemia associated with poor clinical outcome 1 . The preferential involvement of chromatin-associated factors as MLL fusion partners belies a dependency on transcription control 2 . Despite recent progress made in targeting chromatin regulators in cancer 3 , available therapies for this well-characterized disease remain inadequate, prompting the need to identify new targets for therapeutic intervention. Here, using unbiased CRISPR–Cas9 technology to perform a genome-scale loss-of-function screen in an MLL-AF4-positive acute leukaemia cell line, we identify ENL as an unrecognized gene that is specifically required for proliferation in vitro and in vivo . To explain the mechanistic role of ENL in leukaemia pathogenesis and dynamic transcription control, a chemical genetic strategy was developed to achieve targeted protein degradation. Acute loss of ENL suppressed the initiation and elongation of RNA polymerase II at active genes genome-wide, with pronounced effects at genes featuring a disproportionate ENL load. Notably, an intact YEATS chromatin-reader domain was essential for ENL-dependent leukaemic growth. Overall, these findings identify a dependency factor in acute leukaemia and suggest a mechanistic rationale for disrupting the YEATS domain in disease.

To report the findings of the 2019 Society for Hematopathology/European Association for Haematopathology Workshop within the categories of reactive eosinophilia, hypereosinophilic syndrome (HES), germline disorders with eosinophilia (GDE), and myeloid and lymphoid neoplasms associated with eosinophilia (excluding entities covered by other studies in this series). The workshop panel reviewed 109 cases, assigned consensus diagnosis, and created diagnosis-specific sessions. The most frequent diagnosis was reactive eosinophilia (35), followed by acute leukemia (24). Myeloproliferative neoplasms (MPNs) received 17 submissions, including chronic eosinophilic leukemia, not otherwise specified (CEL, NOS). Myelodysplastic syndrome (MDS), MDS/MPN, and therapy-related myeloid neoplasms received 11, while GDE and HES received 12 and 11 submissions, respectively. Hypereosinophilia and HES are defined by specific clinical and laboratory criteria. Eosinophilia is commonly reactive. An acute leukemic onset with eosinophilia may suggest core-binding factor acute myeloid leukemia, blast phase of chronic myeloid leukemia, BCR-ABL1-positive leukemia, or t(5;14) B-lymphoblastic leukemia. Eosinophilia is rare in MDS but common in MDS/MPN. CEL, NOS is a clinically aggressive MPN with eosinophilia as the dominant feature. Bone marrow morphology and cytogenetic and/or molecular clonality may distinguish CEL from HES. Molecular testing helps to better subclassify myeloid neoplasms with eosinophilia and to identify patients for targeted treatments.

ZBTB7A is frequently mutated in acute myeloid leukemia (AML) with t(8;21) translocation. However, the oncogenic collaboration between mutated ZBTB7A and the RUNX1–RUNX1T1 fusion gene in AML t(8;21) remains unclear. Here, we investigate the role of ZBTB7A and its mutations in the context of normal and malignant hematopoiesis. We demonstrate that clinically relevant ZBTB7A mutations in AML t(8;21) lead to loss of function and result in perturbed myeloid differentiation with block of the granulocytic lineage in favor of monocytic commitment. In addition, loss of ZBTB7A increases glycolysis and hence sensitizes leukemic blasts to metabolic inhibition with 2-deoxy-d-glucose. We observed that ectopic expression of wild-type ZBTB7A prevents RUNX1-RUNX1T1-mediated clonal expansion of human CD34+ cells, whereas the outgrowth of progenitors is enabled by ZBTB7A mutation. Finally, ZBTB7A expression in t(8;21) cells lead to a cell cycle arrest that could be mimicked by inhibition of glycolysis. Our findings suggest that loss of ZBTB7A may facilitate the onset of AML t(8;21), and that RUNX1-RUNX1T1-rearranged leukemia might be treated with glycolytic inhibitors.

Disease recurrence after therapy, due to the persistence of resistant leukemic cells, represents a fundamental problem in the treatment of leukemia. Elucidating the mechanisms responsible for the maintenance of leukemic cells, before and after treatment, is therefore critical to identify curative modalities. It has become increasingly clear that cell-autonomous mechanisms are not solely responsible for leukemia maintenance. Here, we report a role for Pml in mesenchymal stem cells (MSCs) in supporting leukemic cells of both CML and AML. Mechanistically, we show that Pml regulates pro-inflammatory cytokines within MSCs, and that this function is critical in sustaining CML-KLS and AML ckit + leukemic cells non-cell autonomously. Persistence of resistant leukemic cells after therapy is the main cause of relapse. Here, the authors show that mesenchymal stem cells-derived PML is involved in the maintenance of leukemia cells through Cxcl1 and IL6 and that PML inhibition enhances sensitivity to chemotherapy.

The updated International Consensus Classification (ICC) of B-acute lymphoblastic leukemia (B-ALL) and T-acute lymphoblastic leukemia (T-ALL) includes both revisions to subtypes previously outlined in the 2016 WHO classification and several newly described entities. The ICC classification incorporates recent clinical, cytogenetic, and molecular data, with a particular emphasis on whole transcriptome analysis and gene expression (GEX) clustering studies. B-ALL classification is modified to further subclassify BCR::ABL1-positive B-ALL and hypodiploid B-ALL. Additionally, nine new categories of B-ALL are defined, including seven that contain distinguishing gene rearrangements, as well as two new categories that are characterized by a specific single gene mutation. Four provisional entities are also included in the updated B-ALL classification, although definitive identification of these subtypes requires GEX studies. T-ALL classification is also updated to incorporate BCL11B-activating rearrangements into early T-precursor (ETP) ALL taxonomy. Additionally, eight new provisional entities are added to the T-ALL subclassification. The clinical implications of the new entities are discussed, as are practical approaches to the use of different technologies in diagnosis. The enhanced specificity of the new classification will allow for improved risk stratification and optimized treatment plans for patients with ALL.

Recently, mutations of the GATA binding protein 2 ( GATA2 ) gene were identified in acute myeloid leukemia (AML) patients with CEBPA double mutations ( CEBPA double-mut ), but the interaction of this mutation with other genetic alterations and its dynamic changes during disease progression remain to be determined. In this study, 14 different missense GATA2 mutations, which were all clustered in the highly conserved N-terminal zinc finger 1 domain, were identified in 27.4, 6.7, and 1 % of patients with CEBPA double-mut , CEBPA single-mut , and CEBPA wild type, respectively. All but one patient with GATA2 mutation had concurrent CEBPA mutation. GATA2 mutations were closely associated with younger age, FAB M1 subtype, intermediate-risk cytogenetics, expression of HLA-DR, CD7, CD15, or CD34 on leukemic cells, and CEBPA mutation, but negatively associated with FAB M4 subtype, favorable-risk cytogenetics, and NPM1 mutation. Patients with GATA2 mutation had significantly better overall survival and relapse-free survival than those without GATA2 mutation. Sequential analysis showed that the original GATA2 mutations might be lost during disease progression in GATA2 -mutated patients, while novel GATA2 mutations might be acquired at relapse in GATA2- wild patients. In conclusion, AML patients with GATA2 mutations had distinct clinic-biological features and a favorable prognosis. GATA2 mutations might be lost or acquired at disease progression, implying that it was a second hit in the leukemogenesis of AML, especially those with CEBPA mutation.

Purpose Dinaciclib inhibits cyclin-dependent kinases 1, 2, 5, and 9 with a better therapeutic index than flavopiridol in preclinical studies. This study assessed the activity of dinaciclib in acute leukemia both in the clinic and in vitro. Methods Adults with relapsed/refractory acute myeloid leukemia ( n  = 14) and acute lymphoid leukemia ( n  = 6) were treated with dinaciclib 50 mg/m 2 given as a 2-h infusion every 21 days. Results Most patients had dramatic but transient reduction in circulating blasts; however, no remissions were achieved on this schedule. The most common toxicities were gastrointestinal, fatigue, transaminitis, and clinical and laboratory manifestations of tumor lysis syndrome, including one patient who died of acute renal failure. Dinaciclib pharmacokinetics showed rapid (2 h) achievement of maximum concentration and a short elimination/distribution phase. Pharmacodynamic studies demonstrated in vivo inhibition of Mcl-1 expression and induction of PARP cleavage in patients’ peripheral blood mononuclear cells 4 h after dinaciclib infusion, but the effects were lost by 24 h and did not correlate with clinical outcome. Correlative in vitro studies showed that prolonged exposures to dinaciclib, at clinically attainable concentrations, result in improved leukemia cell kill. Conclusions While dinaciclib given as a 2-h bolus did not exhibit durable clinical activity, pharmacokinetic and pharmacodynamic data support the exploration of prolonged infusion schedules in future trials in patients with acute leukemias.

The addition of blinatumomab to consolidation chemotherapy in adults with B-cell precursor acute lymphoblastic leukemia who had minimal residual disease–negative status after treatment improved overall and relapse-free survival.

Mutations in the protein tyrosine phosphatase SHP2 affect cells in the bone marrow environment, which leads to aberrant activation of resident haematopoietic stem cells and thereby contributes to the development of leukaemia. A mutated microenvironment in leukaemia Hereditary mutations in the tyrosine phosphatase SHP2 (encoded by PTPN11 ), part of the Ras signalling pathway, have been linked to a syndrome leading to an increased risk of developing leukaemia. Previous studies in mouse models have shown that the function of haematopoietic stem cells carrying these mutations is defective, which suggests a cell-autonomous effect. Cheng-Kui Qu and colleagues find that the mutations also affect cells in the bone marrow environment, blocking their normal control on haematopoietic stem cells and thereby promoting the development of leukaemia. Administration of CCL3 receptor antagonists effectively reversed oncogenesis driven by the Ptpn11 -mutated bone marrow microenvironment. Germline activating mutations of the protein tyrosine phosphatase SHP2 (encoded by PTPN11 ), a positive regulator of the RAS signalling pathway 1 , are found in 50% of patients with Noonan syndrome 2 . These patients have an increased risk of developing leukaemia 3 , especially juvenile myelomonocytic leukaemia (JMML), a childhood myeloproliferative neoplasm (MPN). Previous studies have demonstrated that mutations in Ptpn11 induce a JMML-like MPN through cell-autonomous mechanisms that are dependent on Shp2 catalytic activity 4 , 5 , 6 , 7 . However, the effect of these mutations in the bone marrow microenvironment remains unclear. Here we report that Ptpn11 activating mutations in the mouse bone marrow microenvironment promote the development and progression of MPN through profound detrimental effects on haematopoietic stem cells (HSCs). Ptpn11 mutations in mesenchymal stem/progenitor cells and osteoprogenitors, but not in differentiated osteoblasts or endothelial cells, cause excessive production of the CC chemokine CCL3 (also known as MIP-1α), which recruits monocytes to the area in which HSCs also reside. Consequently, HSCs are hyperactivated by interleukin-1β and possibly other proinflammatory cytokines produced by monocytes, leading to exacerbated MPN and to donor-cell-derived MPN following stem cell transplantation. Remarkably, administration of CCL3 receptor antagonists effectively reverses MPN development induced by the Ptpn11 -mutated bone marrow microenvironment. This study reveals the critical contribution of Ptpn11 mutations in the bone marrow microenvironment to leukaemogenesis and identifies CCL3 as a potential therapeutic target for controlling leukaemic progression in Noonan syndrome and for improving stem cell transplantation therapy in Noonan-syndrome-associated leukaemias.

Leukemia is the most prevalent form of blood cancer, affecting individuals across all age groups. Early and accurate diagnosis is crucial for effective treatment and improved clinical outcomes. Peripheral blood smear analysis, a key non-invasive diagnostic tool, often suffers from subjective interpretation, inter-observer variability, and a lack of readily available expertise. Although deep learning approaches, particularly Convolutional Neural Networks (CNNs), have demonstrated exceptional performance in binary classification tasks, multiclass classification of leukemia subtypes remains challenging due to limited data availability and morphological similarities between subtypes. This study presents a novel hybrid methodology that combines pre-trained CNN architectures, including VGG16, InceptionV3, and ResNet50, with advanced classification models such as Random Forest (RF), Support Vector Machine (SVM), Extreme Gradient Boosting (XGBoost), and the deep learning-based Multi-Layer Perceptron (MLP). The method leverages publicly available datasets, the Acute Lymphoblastic Leukemia Image Database (ALL-IDB) and the Munich AML Morphology Dataset, to classify healthy cells, lymphoblasts, and myeloblasts. Pre-trained CNNs are employed for feature extraction, while the classifiers refine the predictions for improved accuracy. The proposed approach demonstrated exceptional performance, with the InceptionV3 + SVM combination achieving the highest accuracy of 88%, followed closely by VGG16 + XGBoost at 87%. MLP-based models also achieved strong results, effectively capturing non-linear patterns in the data. In contrast, ResNet50 exhibited limitations, likely due to overfitting caused by the small dataset. The novelty of this work lies in the integration of pre-trained deep learning architectures with hybrid classification techniques, enabling robust multiclass classification in data-constrained scenarios. This innovative approach offers a scalable and precise diagnostic tool, improving the speed and reliability of leukemia subtype identification and providing significant potential to enhance clinical decision-making and patient care.