Flow cytometry in acute myeloid leukemia and detection of minimal residual disease.

Acute myeloid leukemia (AML) is a common type of acute leukemia (AL), belonging to malignant tumors of the hematopoietic system with the characteristics of rapid disease development, control with extreme difficulties, easy recurrence, poor prognosis, and incidence rate increasing with age. The traditionally diagnostic standard of French American British (FAB), being based on the morphological examination with high human subjectivity, can no longer meet the demand of clinical diagnosis and treatment of AML. Requirements of objective accuracy and low-dose sample, have become the indispensable method for AML diagnosis and monitoring prognosis. Flow cytometry is a modern technology that can quickly and accurately detect the series, antigen distribution, differentiation stage of AML cells, minimal residual lesions after AML therapy, so as to provide the great significance in guiding clinical diagnosis, hierarchical treatment, and prognosis judgement. This article will systematically elaborate on the application of flow cytometry in the diagnosis and classification of AML, and the detection of minimal residual lesions, thereby providing reference significance for dynamic monitoring and prognostic observation of AML with different immune subtypes of FAB.

CAE-ResVGG FusionNet: A Feature Extraction Framework Integrating Convolutional Autoencoders and Transfer Learning for Immature White Blood Cells in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a highly aggressive cancer form that affects myeloid cells, leading to the excessive growth of immature white blood cells (WBCs) in both bone marrow and peripheral blood. Timely AML detection is crucial for effective treatment and patient well-being. Currently, AML diagnosis relies on the manual recognition of immature WBCs through peripheral blood smear analysis, which is time-consuming, prone to errors, and subject to inter-observers' variation. This study aimed to develop a computer-aided diagnostic framework for AML, called "CAE-ResVGG FusionNet", that precisely identifies and classifies immature WBCs into their respective subtypes. The proposed framework leverages an integrated approach, by combining a convolutional autoencoder (CAE) with finely tuned adaptations of the VGG19 and ResNet50 architectures to extract features from CAE-derived embeddings. The process begins with a binary classification model distinguishing between mature and immature WBCs followed by a multiclassifier further classifying immature cells into four subtypes: myeloblasts, monoblasts, erythroblasts, and promyelocytes. The CAE-ResVGG FusionNet workflow comprises four primary stages, including data preprocessing, feature extraction, classification, and validation. The preprocessing phase involves applying data augmentation methods using geometric transformations and synthetic image generation using the CAE to address imbalance in the WBC distribution. Feature extraction involves image embedding and transfer learning, where CAE-derived image representations are used by a custom integrated model of VGG19 and ResNet50 pretrained models. The classification phase employs a weighted ensemble approach that leverages VGG19 and ResNet50, where the optimal weighting parameters are selected using a grid search. The model performance was assessed during the validation phase using the overall accuracy, precision, and sensitivity, while the area under the receiver characteristic curve (AUC) was used to evaluate the model's discriminatory capability. The proposed framework exhibited notable results, achieving an average accuracy of 99.9%, sensitivity of 91.7%, and precision of 98.8%. The model demonstrated exceptional discriminatory ability, as evidenced by an AUC of 99.6%. Significantly, the proposed system outperformed previous methods, indicating its superior diagnostic ability.

Obesity Promotes the Ceramide-Mediated NADPH Oxidase in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a type of blood cancer of the myeloid cell lineage. Obesity is characterized by an increase in body weight that results in excessive fat accumulation. Obesity has been associated with an increased incidence of many cancers, including blood cancers. This study evaluated the role obesity in AML progression in a novel transgenic mouse model developed by crossing Flt3ITD mice with Lepob/ob mice. Leukemia burden was augmented in obese AML mice. In addition, it was determined that obesity upregulated the ceramide-mediated and ceramide-1-phosphate-mediated NADPH oxidase 2 (NOX2). Notably, increased oxidative pathways has been attributed to disease progression in AML. Taken together, this study demonstrates a direct link between obesity and the progression of AML in part by augmenting the ceramide mediated NOX2.

Association between ABO blood groups and hematological myeloid neoplasms in adolescents and adults.

Background: Prior research suggests a potential link between ABO blood types and susceptibility to various malignancies. The correlation between ABO blood types and hematological myeloid neoplasms, however, remains inadequately explored. Objective: This study investigates the association between ABO blood groups and the incidence of hematological myeloid neoplasms in adolescents and adults. Methods: In this retrospective clinical study, 1,022 adolescent and adult cases of myeloid neoplasms diagnosed at our institution were initially considered. After excluding conditions potentially linked to ABO blood types from prior studies, 792 eligible cases were analyzed. These cases were categorized based on disease subtypes and compared with a control group for blood type distribution. Results: Our findings reveal a significantly higher prevalence of blood type A in patients with myeloid neoplasms compared to the control group, except for chronic myelocytic leukemia and myeloproliferative neoplasms. Conversely, the prevalence of blood type AB in myeloid neoplasms was notably lower than in the control group. Conclusion: The study suggests a potential association between ABO blood types and the risk of developing hematological myeloid neoplasms in adolescents and adults. Further research is warranted to elucidate the underlying mechanisms of this relationship.

Outcome of adolescents and young adult acute myeloid leukemia patients compared with middle-aged patients: A single centre retrospective experience.

Adult acute myeloid leukemia (AML) patients under the age of 60 often receive similar intensive treatments, while outcomes between the adolescent and young adult (AYA) age group (18-39) and middle-aged adults (40-60 years) were seldom reported. We aim to study the characteristics and outcomes of AYA patients in comparison to middle-aged adults. A retrospective analysis was performed on AYA patients treated at Princess Margaret Cancer Center between 2008 and 2018. The primary outcomes include overall survival (OS), cumulative incidence of relapse (CIR), and non-relapse mortality (NRM). A total of 174 AYA patients and 176 middle-aged patients were included, with propensity score matching adjusting for potential major confounders. Comparing AYA and middle-aged patients, 5-year OS rates were similar at 54.6 % vs. 56.5 % (p=0.91), CIR rates at 29.5 % vs. 23.1 % (p=0.31), and similar NRM rates. Notably, non-transplanted AYA patients had a significantly higher CIR (39.8 %) compared to middle-aged patients (19.6 %) (p=0.0324), with more primary refractory/early relapsing disease. An observed trend toward improved OS in AYA patients post-2015 coincided with FLAG-IDA and haploidentical transplant implementations. In conclusion, the study suggests that AYA patients, particularly those not undergoing transplantation, may benefit from more intensive treatment strategies, emphasizing the need for tailored approaches in this age group.

Selective translation of nuclear mitochondrial respiratory proteins reprograms succinate metabolism in AML development and chemoresistance.

Mitochondrial adaptations dynamically reprogram cellular bioenergetics and metabolism and confer key properties for human cancers. However, the selective regulation of these mitochondrial responses remains largely elusive. Here, inspired by a genetic screening in acute myeloid leukemia (AML), we identify RAS effector RREB1 as a translational regulator and uncover a unique translation control system for nuclear-encoded mitochondrial proteins in human cancers. RREB1 deletion reduces mitochondrial activities and succinate metabolism, thereby damaging leukemia stem cell (LSC) function and AML development. Replenishing complex II subunit SDHD rectifies these deficiencies. Notably, inhibition of complex II re-sensitizes AML cells to venetoclax treatment. Mechanistically, a short RREB1 variant binds to a conserved motif in the 3' UTRs and cooperates with elongation factor eEF1A1 to enhance protein translation of nuclear-encoded mitochondrial mRNAs. Overall, our findings reveal a unique translation control mechanism for mitochondrial adaptations in AML pathogenesis and provide a potential strategy for targeting this vulnerability of LSCs.

[Cost-effectiveness analysis in the treatment of hematologic malignancies].

Recent advancements in treatment have improved the prognosis of hematologic malignancies. However, the increasing cost of therapeutic drugs has become an urgent issue. Cost-effectiveness analysis is performed using the incremental cost-effective ratio (ICER), a value calculated by dividing the incremental cost by the incremental quality-adjusted life year (QALY). The ICER must be compared with the willingness-to-pay (WTP) threshold, which differs between countries. Since the analysis should be made over a long time horizon, it is necessary to model and extrapolate the long-term outcomes of clinical trials to calculate cumulative costs and QALYs. This article discusses several approaches to cost-effectiveness analysis for chronic myelogenous leukemia, multiple myeloma, and CAR-T therapy. As even expensive treatments could be cost-effective if they provide long treatment-free survival, it is essential to judge cost-effectiveness by an appropriate method, rather than price alone.

[Molecular profiling of myeloid/natural killer (NK) cell precursor acute leukemia].

Myeloid/natural killer (NK) cell precursor acute leukemia (MNKPL) has been described based on its clinical phenotype and immunophenotype, and proposed as a unique leukemia entity. However, due to its rarity and lack of defined distinctive molecular characteristics, there is currently no international consensus on this disease concept. We performed multi-omics analysis and revealed that MNKPL is distinct from acute myeloid leukemia, T-cell acute lymphoblastic leukemia, and mixed-phenotype acute leukemia. NOTCH1 and RUNX3 activation and BCL11B downregulation are hallmarks of MNKPL. Although NK cells have been classically considered to be lymphoid lineage-derived, our single-cell analysis using MNKPL cells suggested that NK cells and myeloid cells share common progenitor cells. Our retrospective case study uncovered that outcomes of MNKPL are unsatisfactory, even with hematopoietic cell transplantation. Multi-omics analysis and in vitro drug sensitivity assays revealed increased sensitivity to L-asparaginase and reduced levels of asparagine synthetase, supporting the clinically observed effectiveness of L-asparaginase.

[Aberrant mitochondrial dynamics in myeloid neoplasms].

Age-related clonal hematopoiesis and myeloid malignancies arise from hematopoietic stem cells and progenitors with genetic abnormalities. Advances in next-generation sequencing technology have led to the identification of a wide variety of genetic alterations involved in disease onset. However, it remains unclear how diverse genetic alterations, lacking disease specificity, lead to the development of myeloid malignancies and the progression of clonal hematopoiesis. Mitochondrial abnormalities and their roles in various pathological conditions such as aging, inflammation, neurological diseases, cardiac diseases, and cancer have recently been revealed, and have garnered attention as new therapeutic targets. This review focuses on regulation of mitochondrial dynamics and outlines the role of mitochondria in myeloid malignancies and clonal hematopoiesis.

[Allogeneic transplantation as a therapeutic option for atypical chronic myeloid leukemia].

Atypical chronic myeloid leukemia (aCML) is a rare disease classified as a myelodysplastic/myeloproliferative neoplasm (MDS/MPN). Recent advances in gene mutational profiling have clarified the characteristics of aCML as a disease entity relative to other MDS/MPNs. Although some studies suggest the efficacy of DNA demethylating agents and tyrosine kinase inhibitors, data about these agents are limited due to the small number of patients. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is only therapeutic option that can provide durable remission for aCML and other MDS/MPNs. Retrospective studies from Europe and Japan revealed the clinical results of allo-HSCT for aCML. This review summarizes the pathogenesis of aCML and the development of allo-HSCT and other therapeutic options.

[Pediatric acute myeloid leukemia].

Acute myeloid leukemia (AML) accounts for approximately 25% of pediatric leukemia cases in Japan, with approximately 150 patients being newly diagnosed with AML annually. Pediatric acute myeloid leukemia is classified into three groups: myeloid leukemia associated with Down syndrome (ML-DS), acute promyelocytic leukemia (APL), and de novo AML. Patients with ML-DS have an event-free survival rate over 80%; however, relapsed patients have dismal outcomes, even if they receive hematopoietic cell transplantation. APL is curable with all-trans retinoic acid and arsenic trioxide. In de novo AML, 10% of patients fail to achieve remission, and approximately 30% of patients who successfully achieve remission subsequently experience AML relapse. This review highlights the therapeutic approach for these three diseases with context from past clinical studies in Japan, and shares promising new therapeutic options for relapsed/refractory de novo AML.

[Chronic myeloid leukemia: 2024 update on novel therapeutic strategies].

Many patients with chronic myeloid leukemia (CML) can now maintain response thanks to the advent of tyrosine kinase inhibitors (TKIs) and STAMP inhibitors, but adverse events associated with prolonged TKI therapy have become a problem. Adequate management of adverse events is key to successful treatment, as some can significantly impact the patient's prognosis. The goal of CML treatment was once to prevent acute transformation, but now that many patients achieve deep remission and long-term survival, the goal has shifted to achieving long-term treatment free remission (TFR). It is essential to carefully consider disease risk, patient background, and adverse events of each therapeutic agent in order to make the appropriate choice. This article reviews the treatment of chronic phase CML (CML-CP) as described in the 2023 edition of the Guidelines for Hematopoietic Tumors, focusing on treatment options for first-line CML-CP, dose optimization of ponatinib, outcomes with the new CML drug asciminib, and TFR.

[Mitochondrial metabolism in AML cells].

Mitochondrial metabolic dependencies characteristic of acute myeloid leukemia (AML) have recently been identified, demonstrating that metabolic enzymes regulate AML gene expression and control cell differentiation and stemness. These mitochondrial metabolic adaptations occur independently of underlying genomic abnormalities and contribute to chemotherapy resistance and relapse. Mitochondrial alterations also lead to metabolic vulnerability of AML cells, whose metabolism is characterized by dependence on oxidative phosphorylation, fatty acid oxidation, reactive oxygen species (ROS) production, and mitochondrial dynamics. Currently, mitochondrial properties of AML cells and leukemia stem cells are being investigated, focusing on metabolism, signal transduction, mitochondrial respiration, ROS generation, and mitophagy. In addition, mitochondria-targeted agents have shown promising results in clinical trials. This paper outlines recent findings from preclinical and clinical trials on the utility of agents targeting mitochondria-related molecules and metabolic pathways and their efficacy in combination with existing chemotherapies.

[The role and regulation of EVI1 in normal hematopoiesis and hematopoietic malignancies].

EVI1 is a zinc finger transcription factor encoded by the MECOM locus and is essential for the development and maintenance of hematopoietic stem cells. However, overexpression of EVI1 in various myeloid malignancies is associated with aggressive clinical behavior and poor outcome. The locus encodes multiple isoforms that are differentially acting and independently regulated. EVI1 interacts with a variety of transcription and epigenetic factors via different domains. It also regulates cell survival, differentiation, and proliferation through a variety of mechanisms, including transcriptional activation and repression, regulation of other transcription factors' activity, and chromatin remodeling. While the mechanism by which 3q26 translocation leads to high EVI1 expression through enhancer hijacking of genes active in myeloid development is now better understood, regulation of EVI1 expression in the absence of chromosomal translocations and in normal hematopoiesis remains unclear. Recent studies have provided insight into the regulatory mechanisms of EVI1 expression and action, which may lead to development of targeted therapies in the near future.

Acute promyelocytic leukemia: A rare presentation without systemic disease.

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia characterized by an abnormal proliferation of promyelocytes. It is often associated with an aggressive clinical presentation involving complex coagulopathies including disseminated intravascular coagulation, with a significant risk of bleeding and/or thrombosis if treatment with all-trans-retinoic acid (ATRA) is not rapidly initiated. Here we present a unique case of APL which was isolated to femoral bone lesions, without definitive evidence of peripheral blood or bone marrow involvement, and without systemic sequelae.

Case report: Combination therapy with selinexor, decitabine and half-dose CAG regimen for relapsed elderly acute myeloid leukemia.

The treatment of elderly patients diagnosed with acute myeloid leukemia (AML) poses significant challenges. Currently, one promising strategy in therapeutic interventions for geriatric individuals revolves around the utilization of small molecule targeted drugs either independently or in conjunction with demethylating agents. In this report, we present the successful attainment of complete remission in an elderly female patient with relapsed AML, the patient underwent treatment with a combination of Selinexor, decitabine, and a half-dose CAG regimen for two cycles. Subsequently, the patient has sustained this remission through consolidation therapy involving a medium dose of Ara-c. This therapeutic regimen has demonstrated favorable outcomes in the management of relapsed AML in elderly individuals. Furthermore, the adverse reactions were manageable. In order to devise an efficacious treatment regimen for elderly patients suffering from relapsed and refractory acute myeloid leukemia, it is imperative to incorporate a larger cohort of cases for clinical investigation.

Hematopoietic and leukemic stem cells homeostasis: the role of bone marrow niche.

The bone marrow microenvironment (BMM) has highly specialized anatomical characteristics that provide a sanctuary place for hematopoietic stem cells (HSCs) that allow appropriate proliferation, maintenance, and self-renewal capacity. Several cell types contribute to the constitution and function of the bone marrow niche. Interestingly, uncovering the secrets of BMM and its interaction with HSCs in health paved the road for research aiming at better understanding the concept of leukemic stem cells (LSCs) and their altered niche. In fact, they share many signals that are responsible for interactions between LSCs and the bone marrow niche, due to several biological similarities between LSCs and HSCs. On the other hand, LSCs differ from HSCs in their abnormal activation of important signaling pathways that regulate survival, proliferation, drug resistance, invasion, and spread. Targeting these altered niches can help in better treatment choices for hematological malignancies and bone marrow disorders in general and acute myeloid leukemia (AML) in particular. Moreover, targeting those niches may help in decreasing the emergence of drug resistance and lower the relapse rate. In this article, the authors reviewed the most recent literature on bone marrow niches and their relations with either normal HSCs and AML cells/LSC, by focusing on pathogenetic and therapeutic implications.

Epitope prime editing shields hematopoietic cells from CD123 immunotherapy for acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant cancer characterized by abnormal differentiation of hematopoietic stem and progenitor cells (HSPCs). While chimeric antigen receptor T (CAR-T) cell immunotherapies target AML cells, they often induce severe on-target/off-tumor toxicity by attacking normal cells expressing the same antigen. Here, we used base editors (BEs) and a prime editor (PE) to modify the epitope of CD123 on HSPCs, protecting healthy cells from CAR-T-induced cytotoxicity while maintaining their normal function. Although BE effectively edits epitopes, complex bystander products are a concern. To enhance precision, we optimized prime editing, increasing the editing efficiency from 5.9% to 78.9% in HSPCs. Epitope-modified cells were resistant to CAR-T lysis while retaining normal differentiation and function. Furthermore, BE- or PE-edited HSPCs infused into humanized mice endowed myeloid lineages with selective resistance to CAR-T immunotherapy, demonstrating a proof-of-concept strategy for treating relapsed AML.

Effect of AML-exosomes on the cellular and molecular properties of bone marrow mesenchymal stromal cells: Expression of JAK/STAT signaling genes.

PURPOSE OF STUDY: Despite the various therapeutic options introduced for AML treatment, therapy resistance and relapse are still the main obstacles. It is well known that alterations in the bone marrow microenvironment (BMM) play a crucial role in leukemia growth and the treatment failure of AML. Evidence shows that exosomes alter the components of BMM in a way that support leukemia survival, leading to chemoresistance. In this study, we evaluated the effect of AML exosomes on the biological functions of human bone marrow mesenchymal stromal cells (h BM-MSCs), especially alteration in the expression of the JAK/STAT signaling genes, as a leukemia-favoring pathway. METHOD: Exosomes were isolated from the HL-60 cell line and characterized using flow cytometry, Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) technique. The exosome protein content was assessed using a bicinchoninic acid (BCA) protein assay kit in order to determine the concentration of exosomes. Subsequently, MSCs were treated with varying concentrations of AML exosomes, and data was obtained using MTT, cell cycle, apoptosis, and ki67 assays. Additionally, gene expression analysis was conducted through qRT-PCR. RESULT: AML exosomes regulated the viability and survival of MSCs in a concentration-dependent manner. The qRT-PCR data revealed that treatment with AML exosomes at a concentration of 50 µg/mL led to a significant upregulation of JAK2, STAT3, and STAT5 genes in MSCs. CONCLUSION: Because the JAK/STAT signaling pathway has been shown to play a role in the proliferation and survival of leukemic cells, our results suggest that AML exosomes stimulate MSCs to activate this pathway. This activation may impede AML cell apoptosis, potentially leading to chemoresistance and relapse.

A simplified and robust risk stratification model for stem cell transplantation in pediatric acute myeloid leukemia.

The efficacy of stem cell transplantation (SCT) in pediatric acute myeloid leukemia (pAML) remains unsatisfactory due to the limitations of existing prognostic models in predicting efficacy and selecting suitable candidates. This study aims to develop a cytomolecular risk stratification-independent prognostic model for SCT in pAML patients at CR1 stage. The pAML SCT model, based on age, KMT2A rearrangement (KMT2A-r), and minimal residual disease at end of course 1 (MRD1), effectively classifies patients into low-, intermediate-, and high-risk groups. We validate the effectiveness in an internal validation cohort and in four external validation cohorts, consisting of different graft sources and donors. Moreover, by incorporating the FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD) allelic ratio, the pAML SCT model is refined, enhancing its ability to effectively select suitable candidates. We develop a simple and robust risk stratification model for pAML patients undergoing SCT, to aid in risk stratification and inform pretransplant decision-making at CR1 stage.