Dissecting the Immune Landscape of Acute Myeloid Leukemia

Macrophage migration inhibitory factor blockade reprograms macrophages and disrupts prosurvival signaling in acute myeloid leukemia

The malignant microenvironment plays a major role in the development of resistance to therapies and the occurrence of relapses in acute myeloid leukemia (AML). We previously showed that interactions of AML blasts with bone marrow macrophages (MΦ) shift their polarization towards a protumoral (M2-like) phenotype, promoting drug resistance; we demonstrated that inhibiting the colony-stimulating factor-1 receptor (CSF1R) repolarizes MΦ towards an antitumoral (M1-like) phenotype and that other factors may be involved. We investigated here macrophage migration inhibitory factor (MIF) as a target in AML blast survival and protumoral interactions with MΦ. We show that pharmacologically inhibiting MIF secreted by AML blasts results in their apoptosis. However, this effect is abrogated when blasts are co-cultured in close contact with M2-like MΦ. We next demonstrate that pharmacological inhibition of MIF secreted by MΦ, in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF), efficiently reprograms MΦ to an M1-like phenotype that triggers apoptosis of interacting blasts. Furthermore, contact with reprogrammed MΦ relieves blast resistance to venetoclax and midostaurin acquired in contact with CD163+ protumoral MΦ. Using intravital imaging in mice, we also show that treatment with MIF inhibitor 4-IPP and GM-CSF profoundly affects the tumor microenvironment in vivo: it strikingly inhibits tumor vasculature, reduces protumoral MΦ, and slows down leukemia progression. Thus, our data demonstrate that MIF plays a crucial role in AML MΦ M2-like protumoral phenotype that can be reversed by inhibiting its activity and suggest the therapeutic targeting of MIF as an avenue towards improved AML treatment outcomes.

ZEB1 shapes AML immunological niches, suppressing CD8 T cell activity while fostering Th17 cell expansion

Acute myeloid leukemia (AML) progression is influenced by immune suppression induced by leukemia cells. ZEB1, a critical transcription factor in epithelial-to-mesenchymal transition, demonstrates immune regulatory functions in AML. Silencing ZEB1 in leukemic cells reduces engraftment and extramedullary disease in immune-competent mice, activating CD8 T lymphocytes and limiting Th17 cell expansion. ZEB1 in AML cells directly promotes Th17 cell development that, in turn, creates a self-sustaining loop and a pro-invasive phenotype, favoring transforming growth factor β (TGF-β), interleukin-23 (IL-23), and SOCS2 gene transcription. In bone marrow biopsies from AML patients, immunohistochemistry shows a direct correlation between ZEB1 and Th17. Also, the analysis of ZEB1 expression in larger datasets identifies two distinct AML groups, ZEB1high and ZEB1low, each with specific immunological and molecular traits. ZEB1high patients exhibit increased IL-17, SOCS2, and TGF-β pathways and a negative association with overall survival. This unveils ZEB1's dual role in AML, entwining pro-tumoral and immune regulatory capacities in AML blasts.

Coordinated Immune Cell Networks in the Bone Marrow Microenvironment Define the Graft versus Leukemia Response with Adoptive Cellular Therapy

Understanding how intra-tumoral immune populations coordinate to generate anti-tumor responses following therapy can guide precise treatment prioritization. We performed systematic dissection of an established adoptive cellular therapy, donor lymphocyte infusion (DLI), by analyzing 348,905 single-cell transcriptomes from 74 longitudinal bone-marrow samples of 25 patients with relapsed myeloid leukemia; a subset was evaluated by protein-based spatial analysis. In acute myelogenous leukemia (AML) responders, diverse immune cell types within the bone-marrow microenvironment (BME) were predicted to interact with a clonally expanded population of ZNF683 + GZMB + CD8+ cytotoxic T lymphocytes (CTLs) which demonstrated in vitro specificity for autologous leukemia. This population, originating predominantly from the DLI product, expanded concurrently with NK and B cells. AML nonresponder BME revealed a paucity of crosstalk and elevated TIGIT expression in CD8+ CTLs. Our study highlights recipient BME differences as a key determinant of effective anti-leukemia response and opens new opportunities to modulate cell-based leukemia-directed therapy.

Oral azacitidine modulates the bone marrow microenvironment in patients with acute myeloid leukaemia in remission: A subanalysis from the QUAZAR AML-001 trial

Oral azacitidine (Oral-AZA) maintenance therapy improved relapse-free (RFS) and overall survival (OS) significantly versus placebo for AML patients in remission after intensive chemotherapy (IC) in the phase 3 QUAZAR AML-001 study. Immune profiling was performed on the bone marrow (BM) at remission and on-treatment in a subset of patients with the aim of identifying prognostic immune features and evaluating associations of on-treatment immune effects by Oral-AZA with clinical outcomes. Post-IC, increased levels of lymphocytes, monocytes, T cells and CD34 + CD117+ BM cells were prognostically favourable for RFS. CD3+ T-cell counts were significantly prognostic for RFS in both treatment arms. At baseline, high expression of the PD-L1 checkpoint marker was identified on a subset of CD34 + CD117+ BM cells; many of which were PD-L2+. High co-expression of T-cell exhaustion markers PD-1 and TIM-3 was associated with inferior outcomes. Oral-AZA augmented T-cell numbers during early treatment, increased CD4+:CD8+ ratios and reversed T-cell exhaustion. Unsupervised clustering analysis identified two patient subsets defined by T-cell content and expression of T-cell exhaustion markers that were enriched for MRD negativity. These results indicate that Oral-AZA modulates T-cell activity in the maintenance setting of AML, and these immune-mediated responses are associated with clinical outcomes.

Blasts in context: the impact of the immune environment on acute myeloid leukemia prognosis and treatment

Acute myeloid leukemia (AML) is a cancer that originates from the bone marrow (BM). Under physiological conditions, the bone marrow supports the homeostasis of immune cells and hosts memory lymphoid cells. In this review, we summarize our present understanding of the role of the immune microenvironment on healthy bone marrow and on the development of AML, with a focus on T cells and other lymphoid cells. The types and function of different immune cells involved in the AML microenvironment as well as their putative role in the onset of disease and response to treatment are presented. We also describe how the immune context predicts the response to immunotherapy in AML and how these therapies modulate the immune status of the bone marrow. Finally, we focus on allogeneic stem cell transplantation and summarize the current understanding of the immune environment in the post-transplant bone marrow, the factors associated with immune escape and relevant strategies to prevent and treat relapse.

Combined flow cytometry natural killer immunophenotyping and KIR/HLA-C genotyping reveal remarkable differences in acute myeloid leukemia patients, but suggest an overall impairment of the natural killer response

Introduction

Natural killer (NK) cells are key anti-tumor effectors of the innate immunity. Phenotypic differences allow us to discriminate in between three functional stages of maturation, named immature, mature and hypermature that are distinctive in terms of receptor expression, cytokine secretion, cytotoxic properties and organ trafficking. NKs display an impressive repertoire of highly polymorphic germline encoded receptors that can be either activating, triggering the effector's function, or inhibitory, limiting the immune response. In our study, we have investigated peripheral blood NK cells of acute myeloid leukemia (AML) patients.

Methods

The Killer Immunoglobulin-like receptors (KIRs) and the HLA-C genotypes were assessed, as HLA-C molecules are cognate antigens for inhibitory KIRs.

Results

The AA mainly inhibitory KIR haplotype was found in a higher proportion in AML, while a striking low frequency of the 2DS3 characterized the mainly activating Bx haplotype. Flow cytometry immunophenotyping evidenced a lower overall count of NK cells in AML versus healthy controls, with lower percentages of the immature and mature subpopulations, but with a markedly increase of the hypermature NKs. The analysis of the KIR2DL1, KIR2DL2, KIR2DL3, KIR3DL1, and NKG2A inhibitory receptors surface expression revealed a remarkable heterogeneity. However, an overall trend for a higher expression in AML patients could be noticed in all maturation subpopulations. Some of the AML patients with complex karyotypes or displaying a FLT3 gene mutation proved to be extreme outliers in terms of NK cells percentages or inhibitory receptors expression.

Discussion

We conclude that while the genetic background investigation in AML offers important pieces of information regarding susceptibility to disease or prognosis, it is flow cytometry that is able to offer details of finesse in terms of NK numbers and phenotypes, necessary for an adequate individual evaluation of these patients.

Prediction of prognosis and immunotherapy response of amino acid metabolism genes in acute myeloid leukemia

Background

Amino acid (AA) metabolism plays a crucial role in cancer. However, its role in acute myeloid leukemia (AML) is still unavailable. We screened out AA metabolic genes, which related to prognosis, and analyzed their correlation with tumor immune microenvironment in AML.

Methods

We evaluated 472 amino acid metabolism-related genes in 132 AML patients. The predictive risk model was developed according to differentially expressed genes, univariate Cox and LASSO analyses. We validated the risk signature by survival analysis and independence tests. Single-sample gene set enrichment analysis (ssGSEA), tumor immune microenvironment (TME), tumor mutation burden (TMB), functional enrichment, and the IC50 of drugs were assessed to explore the correlations among the risk model, immunity, and drug sensitivity of AML.

Results

Six amino acid metabolism-related genes were confirmed to develop the risk model, including TRH, HNMT, TFEB, SDSL, SLC43A2, and SFXN3. The high-risk subgroup had an immune "hot" phenotype and was related to a poor prognosis. The high-risk group was also associated with more activity of immune cells, such as Tregs, had higher expression of some immune checkpoints, including PD1 and CTLA4, and might be more susceptible to immunotherapy. Xenobiotic metabolism, the reactive oxygen species (ROS) pathway, fatty acid metabolism, JAK/STAT3, and the inflammatory response were active in the high-risk subgroup. Furthermore, the high-risk subgroup was sensitive to sorafenib, selumetinib, and entospletinib. ssGSEA discovered that the processes of glutamine, arginine, tryptophan, cysteine, histidine, L-serine, isoleucine, threonine, tyrosine, and L-phenylalanine metabolism were more active in the high-risk subgroup.

Conclusion

This study revealed that AA metabolism-related genes were correlated with the immune microenvironment of AML patients and could predict the prognosis and immunotherapy response of AML patients.

Regulation of hematopoietic and leukemia stem cells by regulatory T cells

Adult bone marrow (BM) hematopoietic stem cells (HSCs) are maintained in a quiescent state and sustain the continuous production of all types of blood cells. HSCs reside in a specialized microenvironment the so-called HSC niche, which equally promotes HSC self-renewal and differentiation to ensure the integrity of the HSC pool throughout life and to replenish hematopoietic cells after acute injury, infection or anemia. The processes of HSC self-renewal and differentiation are tightly controlled and are in great part regulated through cellular interactions with classical (e.g. mesenchymal stromal cells) and non-classical niche cells (e.g. immune cells). In myeloid leukemia, some of these regulatory mechanisms that evolved to maintain HSCs, to protect them from exhaustion and immune destruction and to minimize the risk of malignant transformation are hijacked/disrupted by leukemia stem cells (LSCs), the malignant counterpart of HSCs, to promote disease progression as well as resistance to therapy and immune control. CD4⁺ regulatory T cells (Tregs) are substantially enriched in the BM compared to other secondary lymphoid organs and are crucially involved in the establishment of an immune privileged niche to maintain HSC quiescence and to protect HSC integrity. In leukemia, Tregs frequencies in the BM even increase. Studies in mice and humans identified the accumulation of Tregs as a major immune-regulatory mechanism. As cure of leukemia implies the elimination of LSCs, the understanding of these immune-regulatory processes may be of particular importance for the development of future treatments of leukemia as targeting major immune escape mechanisms which revolutionized the treatment of solid tumors such as the blockade of the inhibitory checkpoint receptor programmed cell death protein 1 (PD-1) seems less efficacious in the treatment of leukemia. This review will summarize recent findings on the mechanisms by which Tregs regulate stem cells and adaptive immune cells in the BM during homeostasis and in leukemia.

Mapping Cell Phenomics with Multiparametric Flow Cytometry Assays

Phenomics explores the complex interactions among genes, epigenetics, symbiotic microorganisms, diet, and environmental exposure based on the physical, chemical, and biological characteristics of individuals and groups. Increasingly efficient and comprehensive phenotyping techniques have been integrated into modern phenomics-related research. Multicolor flow cytometry technology provides more measurement parameters than conventional flow cytometry. Based on detailed descriptions of cell phenotypes, rare cell populations and cell subsets can be distinguished, new cell phenotypes can be discovered, and cell apoptosis characteristics can be detected, which will expand the potential of cell phenomics research. Based on the enhancements in multicolor flow cytometry hardware, software, reagents, and method design, the present review summarizes the recent advances and applications of multicolor flow cytometry in cell phenomics, illuminating the potential of applying phenomics in future studies.

Integrated analysis reveals distinct molecular, clinical, and immunological features of B7-H3 in acute myeloid leukemia

The role of B7‐H3 in acute myeloid leukemia (AML) is not fully understood. Two previous studies investigating its expression and significances in AML are partially different. In this study, we aimed to systematically characterize the genomic and immune landscape in AML patients with altered B7‐H3 expression using multi‐omics data in the public domain. We found significantly increased B7‐H3 expression in AML compared to either other hematological malignancies or healthy controls. Clinically, high B7‐H3 expression was associated with old age, TP53 mutations, wild‐type WT1 and CEBPA, and the M3 and M5 FAB subtypes. Moreover, we observed that increased B7‐H3 expression correlated significantly with a poor outcome of AML patients in four independent datasets. Gene set enrichment analysis (GSEA) revealed the enrichment of the “EMT” oncogenic gene signatures in high B7‐H3 expressers. Further investigation suggested that B7‐H3 was more likely to be associated with immune‐suppressive cells (macrophages, neutrophils, dendritic cells, and Th17 cells). B7‐H3 was also positively associated with a number of checkpoint genes, such as VISTA (B7‐H5), CD80 (B7‐1), CD86 (B7‐2), and CD70. In summary, we uncovered distinct genomic and immunologic features associated with B7‐H3 expression in AML. This may lead to a better understanding of the molecular mechanisms underlying B7‐H3 dysregulation in AML and to the development of novel therapeutic strategies.

Paving the Way for Immunotherapy in Pediatric Acute Myeloid Leukemia: Current Knowledge and the Way Forward

Simple Summary

Immunotherapy may be an attractive treatment option to increase survival, and to reduce treatment-related side effects, for children with acute myeloid leukemia (AML). While immunotherapies have shown successes in many cancer types, the development and subsequent clinical implementation have proven difficult in pediatric AML. To expedite the development of immunotherapy, it will be crucial to understand which pediatric AML patients are likely to respond to immunotherapies. Emerging research in solid malignancies has shown that the number and phenotype of immune cells in the tumor microenvironment is predictive of response to several types of immunotherapies. Such a predictive model may also be applicable for AML and, thus, knowledge on the immune cells infiltrating the bone marrow environment is needed. Here, we discuss the current state of knowledge on these infiltrating immune cells in pediatric AML, as well as ongoing immunotherapy trials, and provide suggestions concerning the way forward.

Abstract

Immunotherapeutic agents may be an attractive option to further improve outcomes and to reduce treatment-related toxicity for pediatric AML. While improvements in outcome have been observed with immunotherapy in many cancer types, immunotherapy development and implementation into patient care for both adult and pediatric AML has been hampered by an incomplete understanding of the bone marrow environment and a paucity of tumor-specific antigens. Since only a minority of patients respond in most immunotherapy trials across different cancer types, it will be crucial to understand which children with AML are likely to respond to or may benefit from immunotherapies. Immune cell profiling efforts hold promise to answer this question, as illustrated by the development of predictive scores in solid cancers. Such information on the number and phenotype of immune cells during current treatment regimens will be pivotal to generate hypotheses on how and when to intervene with immunotherapy in pediatric AML. In this review, we discuss the current understanding of the number and phenotype of immune cells in the bone marrow in pediatric AML, ongoing immunotherapy trials and how comprehensive immune profiling efforts may pave the way for successful clinical trials (and, ultimately, implementation into patient care).

Vaccine and Cell-based Therapeutic Approaches in Acute Myeloid Leukemia

Over the past decade, our increased understanding of the interactions between the immune system and cancer cells has led to paradigm shifts in the clinical management of solid and hematologic malignancies. The incorporation of immune-targeted strategies into the treatment landscape of acute myeloid leukemia (AML), however, has been challenging. While this is in part due to the inability of the immune system to mount an effective tumor-specific immunogenic response against the heterogeneous nature of AML, the decreased immunogenicity of AML cells also represents a major obstacle in the effort to design effective immunotherapeutic strategies. In fact, AML cells have been shown to employ sophisticated escape mechanisms to evade elimination, such as direct immunosuppression of natural killer cells and decreased surface receptor expression leading to impaired recognition by the immune system. Yet, cellular and humoral immune reactions against tumor-associated antigens (TAA) of acute leukemia cells have been reported and the success of allogeneic stem cell transplantation and monoclonal antibodies in the treatment of AML clearly provides proof that an immunotherapeutic approach is feasible in the management of this disease. This review discusses the recent progress and persisting challenges in cellular immunotherapy for patients with AML.

Dynamic immune profiling identifies the stronger graft-versus-leukemia (GVL) effects with haploidentical allografts compared to HLA-matched stem cell transplantation

Haploidentical stem cell transplantation (haplo-SCT) achieves superior or at least comparable clinical outcomes to HLA-matched sibling donor transplantation (MSDT) in treating hematological malignancies. To define the underlying regulatory dynamics, we analyzed time courses of leukemia burden and immune abundance of haplo-SCT or MSDT from multiple dimension. First, we employed two nonirradiated leukemia mouse models which carried human AML-ETO or MLL-AF9 fusion gene to establish haplo-identical and major histocompatibility (MHC)-matched transplantation models and investigated the immune cell dynamic response during leukemia development in vivo. We found that haplo-matching the MHCs of leukemia cells with recipient mouse T cells prolonged leukemic mice survival and reduced leukemia burden. The stronger graft-versus-leukemia activity in haplo-SCT group mainly induced by decreased apoptosis and increased cytotoxic cytokine secretion including tumor necrosis factor-α, interferon-γ, pore-forming proteins and CD107a secreted by T cells or natural killer cells. Furthermore, we conducted a prospective clinical trial which enrolled 135 patients with t(8;21) acute myeloid leukemia that displayed minimal residual disease before transplantation and underwent either haplo-SCT or MSDT. The results showed that the haplo-SCT slowed the kinetics of the leukemia burden in vivo and reduced the cumulative incidence of relapse compared with MSDT. Ex vivo experiments showed that, 1 year after transplantation, cytotoxic T lymphocytes from the haplo-SCT group had higher cytotoxicity than those from the MSDT group during the same period. Our results unraveled the role of immune cells in superior antileukemia effects of haplo-SCT compared with MSDT.

CAR T cells for other pediatric non-B-cell hematologic malignancies

As CAR T-cell therapy has advanced in B-cell acute lymphoblastic leukemia, research is now underway to develop similar therapies for other lymphoid and myeloid malignancies for pediatric patients. Barriers, including antigen selection and on-target/off-tumor toxicity, have prevented the rapid development of immune-based therapies for T-lineage and myeloid malignancies. More recently, unique strategies have been developed to overcome these barriers, with several products advancing to clinical trials. For T-lineage diseases, targets have focused on CD5, CD7, and CD38, whereas myeloid disease targets have predominately focused on CD123, CD33, and, more recently, CLL-1. This review provides a comprehensive overview of these targets and approaches to overcoming safety concerns in the development of CAR T-cell therapies for pediatric patients with T-lineage and myeloid malignancies.

The MHC-II antigen presentation machinery and B7 checkpoint ligands display distinctive patterns correlated with acute myeloid leukaemias blast cells HLA-DR expression

Acute Myeloid Leukaemia (AML) is a neoplasia characterised by rapid proliferation and an increased rate of relapses. The AML blasts display features of antigen-presenting cells (APC), and thus can directly modulate the anti-tumour T cell responses. The bone marrow of a group consisting of 30 newly diagnosed patients and four healthy donors (HD) was investigated for the expression of HLA-DR, several molecules involved in MHC-II antigen-presentation and MHC-II groove editing, like HLA-DM, CD74 and CLIP, as well as a set of immune checkpoint ligands, like ICOS-L, B7.2, PD-L2 and B7-H3. The patients were further characterised for their genetic anomalies and distributed to favourable, intermediate and adverse ELN risk categories. We were able to show that while 23% of our patients displayed a low level of HLA-DR surface expression, all patients displayed higher HLA-DM and CD74 expression compared to HD. However, a higher CLIP expression was noticed only in the HLA-DR low patients. The co-inhibitory PD-L2 and B7-H3 molecules were increased in the cases with normal HLA-DR expression; oppositely, the co-stimulatory ICOS-L and the dual function B7.2 were significantly increased in the cases with HLA-DR low expression. Furthermore, no favourable ELN risk cases were found within the HLA-DR low group. All in all, these data show that the AML with low versus normal HLA-DR expression display different profiles of MHC class II machinery molecules and B7 ligands, which are correlated with distinct ELN stratification. Furthermore, as our study included healthy individuals, it offers valuable information about the expression levels that should be considered as normal for these markers known to cause differences in peptide repertoires, reflected further in distinct T-cells polarisation pathways.

Identification of an Immune-Related Gene Signature Based on Immunogenomic Landscape Analysis to Predict the Prognosis of Adult Acute Myeloid Leukemia Patients

Acute myeloid leukemia (AML) is a hematopoietic malignancy characterized by highly heterogeneous molecular lesions and cytogenetic abnormalities. Immune disorders in AML and impaired immune cell function have been found to be associated with abnormal karyotypes in AML patients. Immunotherapy has become an alternative therapeutic method that can improve the outcomes of AML patients. For solid tumors, the expression patterns of genes associated with the immune microenvironment provide valuable prognostic information. However, the prognostic roles of immune genes in AML have not been studied as yet. In this study, we identified 136 immune-related genes associated with overall survival in AML patients through a univariate Cox regression analysis using data from TCGA-AML and GTEx datasets. Next, we selected 24 hub genes from among the 136 genes based on the PPI network analysis. The 24 immune-related hub genes further underwent multivariate Cox regression analysis and LASSO regression analysis. Finally, a 6 immune-related gene signature was constructed to predict the prognosis of AML patients. The function of the hub IRGs and the relationships between hub IRGs and transcriptional factors were investigated. We found that higher levels of expression of CSK, MMP7, PSMA7, PDCD1, IKBKG, and ISG15 were associated with an unfavorable prognosis of AML patients. Meanwhile, patients in the TCGA-AML datasets were divided into a high risk score group and a low risk score group, based on the median risk score value. Patients in the high risk group tended to show poorer prognosis [P = 0.00019, HR = 1.89 (1.26–2.83)]. The area under the curve (AUC) was 0.6643. Multivariate Cox Regression assay confirmed that the 6 IRG signature was an independent prognostic factor for AML. The prognostic role of the immune related-gene signature was further validated using an independent AML dataset, GSE37642. In addition, patients in the high risk score group in the TCGA dataset were found to be of an advanced age, IDH mutation, and M5 FAB category. These results suggested that the proposed immune related-gene signature may serve as a potential prognostic tool for AML patients.

A Screening of Antineoplastic Drugs for Acute Myeloid Leukemia Reveals Contrasting Immunogenic Effects of Etoposide and Fludarabine

BACKGROUND

Recent evidence demonstrated that the treatment of acute myeloid leukemia (AML) cells with daunorubicin (DNR) but not cytarabine (Ara-C) results in immunogenic cell death (ICD). In the clinical setting, chemotherapy including anthracyclines and Ara-C remains a gold standard for AML treatment. In the last decade, etoposide (Eto) and fludarabine (Flu) have been added to the standard treatment for AML to potentiate its therapeutic effect and have been tested in many trials. Very little data are available about the ability of these drugs to induce ICD.

METHODS

AML cells were treated with all four drugs. Calreticulin and heat shock protein 70/90 translocation, non-histone chromatin-binding protein high mobility group box 1 and adenosine triphosphate release were evaluated. The treated cells were pulsed into dendritic cells (DCs) and used for in vitro immunological tests.

RESULTS

Flu and Ara-C had no capacity to induce ICD-related events. Interestingly, Eto was comparable to DNR in inducing all ICD events, resulting in DC maturation. Moreover, Flu was significantly more potent in inducing suppressive T regulatory cells compared to other drugs.

CONCLUSIONS

Our results indicate a novel and until now poorly investigated feature of antineoplastic drugs commonly used for AML treatment, based on their different immunogenic potential.

Impact of Bone Marrow miR-21 Expression on Acute Myeloid Leukemia T Lymphocyte Fragility and Dysfunction

BACKGROUND

Acute myeloid leukemia (AML) is a hematopoietic malignancy in which antitumor immunity is impaired. The therapeutic management of AML requires understanding the mechanisms involved in the fragility and immune dysfunction of AML T lymphocytes.

METHODS

In this study, T lymphocytes from healthy donors (HD) and AML patients were used. Extracellular vesicles (EVs) from leukemic cells were screened for their microRNA content and impact on T lymphocytes. Flow cytometry, transcriptomic as well as lentiviral transduction techniques were used to carry out the research.

RESULTS

We observed increased cell death of T lymphocytes from AML patients. EVs from leukemia myeloid cell lines harbored several miRNAs, including miR-21, and were able to induce T lymphocyte death. Compared to that in HD, miR-21 was overexpressed in both the bone marrow fluid and infiltrating T lymphocytes of AML patients. MiR-21 induces T lymphocyte cell death by upregulating proapoptotic gene expression. It also increases the immunosuppressive profile of T lymphocytes by upregulating the IL13, IL4, IL10, and FoxP3 genes.

CONCLUSIONS

Our results demonstrate that miR-21 plays a significant role in AML T lymphocyte dysfunction and apoptosis. Targeting miR-21 may be a novel approach to restore the efficacy of the immune response against AML.

B7-Positive and B7-Negative Acute Myeloid Leukemias Display Distinct T Cell Maturation Profiles, Immune Checkpoint Receptor Expression, and European Leukemia Net Risk Profiles

Acute myeloid leukemia (AML) is generally considered a poorly immunogenic malignancy, displaying a “non-inflamed” leukemia microenvironment (LME), leading to T cell tolerance. However, the immune landscape of AML is much more heterogeneous. Since B7 expression is regarded as a consequence of an interferon-mediated “inflammatory” phenotype, we have investigated by flow cytometry the B7 checkpoint ligands B7.1, B7.2, programmed death ligand 1 (PD-L1), PD-L2, ICOS-L, B7-H3, and B7-H4 on the AML blasts of 30 newly diagnosed patients and their corresponding receptors [cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed death 1 (PD-1), and inducible T cell costimulator (ICOS)] on bone marrow (BM) T cell maturation populations. We could thus evidence B7-negative and B7-positive leukemias either with an isolated expression or part of eight different checkpoint ligand “signatures” that always included an inhibitory B7 molecule. B7-positive AMLs encompassed intermediate and adverse European Leukemia Net (ELN) risk cases and displayed mainly central memory CD4+ T cells with high ICOS levels and effector CD8+ T cells with high PD-1 expression. B7-negative cases were rather classified as AML with recurrent genetic anomalies and displayed predominantly naive T cells, with the exception of NPM1 mutated AMLs, which expressed B7-H3. These different B7 immune profiles suggest that specific immunotherapies are required to target the distinct immune evasion strategies of this genetically heterogeneous disease.

Immunomodulation with pomalidomide at early lymphocyte recovery after induction chemotherapy in newly diagnosed AML and high-risk MDS

An immunosuppressive microenvironment promoting leukemia cell immune escape plays an important role in the pathogenesis of AML. Through its interaction with cereblon, a substrate receptor for the E3 ubiquitin ligase complex, pomalidomide leads to selective ubiquitination of transcription factors Aiolos and Ikaros thereby promoting immune modulation. In this phase I trial, 51 newly diagnosed non-favorable risk AML and high-risk MDS patients were enrolled and treated with AcDVP16 (cytarabine 667 mg/m²/day IV continuous infusion days 1-3, daunorubicin 45 mg/m² IV days 1-3, etoposide 400 mg/m² IV days 8-10) induction therapy followed by dose- and duration-escalation pomalidomide beginning at early lymphocyte recovery. Forty-three patients (AML: n = 39, MDS: n = 4) received pomalidomide. The maximum tolerated dose of pomalidomide was 4 mg for 21 consecutive days. The overall complete remission (CR + CRi) rate, median overall survival, and disease-free survival were 75%, 27.1 and 20.6 months, respectively. Subset analyses revealed 86% CR/CRi rate in AML patients with unfavorable-risk karyotype treated with pomalidomide. Pomalidomide significantly decreased Aiolos expression in both CD4⁺ and CD8⁺ peripheral blood and bone marrow T cells, promoted T cell differentiation, proliferation, and heightened their cytokine production. Finally, pomalidomide induced distinct gene expression changes in immune function-related ontologies in CD4⁺ and CD8⁺ T cells.

Elevated SPINK2 gene expression is a predictor of poor prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) has a high mortality rate and its clinical management remains challenging. The aim of the present study was to identify the hub genes involved in AML. In order to do so, the gene expression data of the GSE9476 database, including 26 AML and 10 normal samples, were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were then identified via bioinformatics analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed on DEGs. Furthermore, the most upregulated genes were selected for further investigation in the Oncomine, gene expression profiling interactive analysis and UALCAN datasets. In total, 1,744 upregulated and 1,956 downregulated genes were detected. The GO and KEGG results revealed that upregulated genes were enriched in metabolic processes, while downregulated genes were associated with the immune response. Serine protease inhibitor Kazal-type 2 (SPINK2) ranked first among all the upregulated genes and was regarded as a hub gene in the development of AML. The overexpression of SPINK2 was validated in 12 patients with AML from the Linyi Central Hospital and in data from the Oncomine and Gene Expression Profiling Interactive Analysis (GEPIA) databases. Furthermore, the UALCAN and GEPIA datasets demonstrated that patients with high SPINK2 levels had shorter survival times. In conclusion, the results from the present study revealed that the SPINK2 gene was upregulated in patients with AML and that elevated SPINK2 expression was associated with poor outcomes in these patients.

Imunophenotypic Evaluation as a Tool for Monitoring Risks for Blood Malignancies in Gas Station Workers

Background:

Gas station workers are exposed to carcinogenic substances with impact on the hematologic and immune systems. The aim was to apply the immunophenotyping as a tool in the biological monitoring.

Methods:

This is a workplace-based case-control study with 49 workers and 26 controls. Medical interviews, hematological exams, and immunophenotyping analyses were performed. According to risk behavior (cleaning flannel and mistrust in the automatic fuel supply) the workers were divided into two groups: low risk (group 1) and high risk (group 2).

Results:

The results showed that CD16, HLA-DR, CD25, CD56+, CD16 CD56 low, and CD56 high expressions were higher in workers when compared to the control group (P =0.020, P =0.001, P =0.001; P =0.034, P=0.023, and P =0.008, respectively). The expressions of CD2, CD8, CD10, CD8low, and CD4/CD8 ratios were lower (P =0.016, P =0.001, P=0.001, P= 0.017, P = 0.0259, and P =0.029, respectively). Headache and paresthesia complaints were associated with workers when compared to the control group (OR = 4.091, 95% CI, 1.400 -11.951, P = 0.014; OR =12.12, 95% CI, 1.505 - 97.61, P =0.004). Using cleaning flannel and mistrust in the automatic fuel supply (risk behaviors) were associated with group 2 (OR = 9.71, 95% CI, 2.60-36.26, P = 0.005; OR = 18.18, 95% CI, 2.04-161.37, P = 0.004).

Conclusions:

The results strengthen the worker’s immunosuppression hypothesis, which may contribute to some disorders and the carcinogenesis process. The evaluation of the immune system by flow cytometry is a promising tool for monitoring blood malignancy risk in addition to regular classic hematological exams.

A skewed distribution and increased PD-1+Vβ+CD4+/CD8+ T cells in patients with acute myeloid leukemia

The limited application of immunotherapy in acute myeloid leukemia (AML) may be due to poor understanding of the global T cell immune dysfunction in AML. In this study, we analyzed the distribution characteristics of 24 TCR Vβ subfamilies in CD3+, CD4+, and CD8+ T cells in AML patients and healthy controls. The percentage of TCR Vβ subfamily T cells was predominately lower in most AML cases, while it was increased in some cases. TCR Vβ2+T cells were increased in AML, particularly TCR Vβ2+CD4+T cells, which were significantly higher. To further address the immunosuppression in different Vβ subfamilies, we characterized the distribution of program death-1 (PD-1)+T cells in TCR Vβ subfamilies of CD4+ and CD8+T cells. Significantly higher levels of PD-1+Vβ+T cells were found for most Vβ subfamilies in most AML cases. A higher percentage of PD-1+Vβ2+T cells with a high number of Vβ2+T cells was found in all of the CD3+, CD4+, and CD8+ T cell subsets. Moreover, increasing PD-1+Vβ7.2, Vβ8+, Vβ14+, Vβ16+, and Vβ22+CD8+T cells were distributed in the AML-M5 subtype group compared with the AML-M3 group. In addition, higher PD-1+ Vβ5.2+ and PD-1+ Vβ12+CD8+T cells were associated with AML patients who had a poor response to chemotherapy. In conclusion, increased PD-1+Vβ+T cells is a common characteristic of AML, higher PD-1+Vβ2+T cells may be associated with a low antileukemia effect, and higher PD-1+Vβ5.2+ and PD-1+Vβ12+CD8+T cells may be related to poor prognosis in AML. These characteristics may be worth considering as immune biomarkers for clinical outcome in AML.