Immune escape and immunotherapy of acute myeloid leukemia

Identification of a novel monocyte/macrophage-related gene signature for predicting survival and immune response in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous hematological tumor with poor immunotherapy effect. This study was to develop a monocyte/macrophage-related prognostic risk score (MMrisk) and identify new therapeutic biomarkers for AML. We utilized differentially expressed genes (DEGs) in combination with single-cell RNA sequencing to identify monocyte/macrophage-related genes (MMGs). Eight genes were selected for the construction of a MMrisk model using univariate Cox regression analysis and LASSO regression analysis. We then validated the MMrisk on two GEO datasets. Lastly, we investigated the immunologic characteristics and advantages of immunotherapy and potential targeted drugs for MMrisk groups. Our study identified that the MMrisk is composed of eight MMGs, including HOPX, CSTB, MAP3K1, LGALS1, CFD, MXD1, CASP1 and BCL2A1. The low MMrisk group survived longer than high MMrisk group (P < 0.001). The high MMrisk group was positively correlated with B cells, plasma cells, CD4 memory cells, Mast cells, CAFs, monocytes, M2 macrophages, Endothelial, tumor mutation, and most immune checkpoints (PD1, Tim-3, CTLA4, LAG3). Furthermore, drug sensitivity analysis showed that AZD.2281, Axitinib, AUY922, ABT.888, and ATRA were effective in high-risk MM patients. Our research shows that MMrisk is a potential biomarker which is helpful to identify the molecular characteristics of AML immunology.

Application of omics in the diagnosis, prognosis, and treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most frequent leukemia in adults with a high mortality rate. Current diagnostic criteria and selections of therapeutic strategies are generally based on gene mutations and cytogenetic abnormalities. Chemotherapy, targeted therapies, and hematopoietic stem cell transplantation (HSCT) are the major therapeutic strategies for AML. Two dilemmas in the clinical management of AML are related to its poor prognosis. One is the inaccurate risk stratification at diagnosis, leading to incorrect treatment selections. The other is the frequent resistance to chemotherapy and/or targeted therapies. Genomic features have been the focus of AML studies. However, the DNA-level aberrations do not always predict the expression levels of genes and proteins and the latter is more closely linked to disease phenotypes. With the development of high-throughput sequencing and mass spectrometry technologies, studying downstream effectors including RNA, proteins, and metabolites becomes possible. Transcriptomics can reveal gene expression and regulatory networks, proteomics can discover protein expression and signaling pathways intimately associated with the disease, and metabolomics can reflect precise changes in metabolites during disease progression. Moreover, omics profiling at the single-cell level enables studying cellular components and hierarchies of the AML microenvironment. The abundance of data from different omics layers enables the better risk stratification of AML by identifying prognosis-related biomarkers, and has the prospective application in identifying drug targets, therefore potentially discovering solutions to the two dilemmas. In this review, we summarize the existing AML studies using omics methods, both separately and combined, covering research fields of disease diagnosis, risk stratification, prognosis prediction, chemotherapy, as well as targeted therapy. Finally, we discuss the directions and challenges in the application of multi-omics in precision medicine of AML. Our review may inspire both omics researchers and clinical physicians to study AML from a different angle.

BRD4 degraders may effectively counteract therapeutic resistance of leukemic stem cells in AML and ALL

Acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) are life-threatening hematopoietic malignancies characterized by clonal expansion of leukemic blasts in the bone marrow and peripheral blood. The epigenetic reader BRD4 and its downstream effector MYC have recently been identified as potential drug targets in human AML and ALL. We compared anti-leukemic efficacies of the small-molecule BET inhibitor JQ1 and the recently developed BRD4 degraders dBET1 and dBET6 in AML and ALL cells. JQ1, dBET1, and dBET6 were found to suppress growth and viability in all AML and ALL cell lines examined as well as in primary patient-derived AML and ALL cells, including CD34+/CD38- and CD34+/CD38+ leukemic stem and progenitor cells, independent of the type (variant) of leukemia or molecular driver expressed in leukemic cells. Moreover, we found that dBET6 overcomes osteoblast-induced drug resistance in AML and ALL cells, regardless of the type of leukemia or the drug applied. Most promising cooperative or even synergistic drug combination effects were seen with dBET6 and the FLT3 ITD blocker gilteritinib in FLT3 ITD-mutated AML cells, and with dBET6 and the multi-kinase blocker ponatinib in BCR::ABL1+ ALL cells. Finally, all BRD4-targeting drugs suppressed interferon-gamma- and tumor necrosis factor-alpha-induced expression of the resistance-related checkpoint antigen PD-L1 in AML and ALL cells, including LSC. In all assays examined, the BRD4 degrader dBET6 was a superior anti-leukemic drug compared with dBET1 and JQ1. Together, BRD4 degraders may provide enhanced inhibition of multiple mechanisms of therapy resistance in AML and ALL.

Strategies to reduce relapse risk in patients undergoing allogeneic stem cell transplantation for acute myeloid leukaemia

Allogeneic stem cell transplantation is a centrally important curative strategy in adults with acute myeloid leukaemia; however, relapse occurs in a significant proportion of patients and remains the leading cause of treatment failure. The prognosis for patients who relapse post-transplant remains poor, and the development of new strategies with the ability to reduce disease recurrence without increasing transplant toxicity remains a priority. In this review, within the context of our understanding of disease biology and the graft-versus-leukaemia (GVL) effect, we will discuss established, evolving and novel approaches for increasing remission rates, decreasing measurable residual disease pretransplant, future methods to augment the GVL effect and the opportunities for post-transplant maintenance. Future progress depends upon the development of innovative trials and networks, which will ensure the rapid assessment of emerging therapies in prospective clinical trials.

Donor lymphocyte infusion after allogeneic haematopoietic cell transplantation for haematological malignancies: basic considerations and best practice recommendations from the EBMT

Since the early description of three patients with relapsed leukaemia after allogeneic haematopoietic cell transplantation (HCT) who obtained complete remission after donor lymphocyte infusions (DLIs), the added value of this procedure to induce or maintain graft-versus-leukaemia immunity has been undisputed. For more than 30 years, DLIs have become common practice as prophylactic, pre-emptive, or therapeutic immunotherapy. However, as with many aspects of allogeneic HCT, centres have developed their own routines and practices, and many questions related to the optimal applications and toxicity, or to the immunobiology of DLI induced tumour-immunity, remain. As a part of the Practice Harmonization and Guidelines Committee and the Cellular Therapy and Immunobiology Working Party of the European Society for Blood and Marrow Transplantation effort, a panel of experts with clinical and translational knowledge in transplantation immunology and cellular therapy met during a 2-day workshop in September, 2023, in Lille, France, and developed a set of consensus-based recommendations for the application of unmanipulated DLI after allogeneic HCT for haematological malignancies. Given the absence of prospective data in the majority of publications, these recommendations are mostly based on retrospective studies and expert consensus.

Pulsed electric field induces exocytosis and overexpression of MAGE antigens in melanoma

Nanosecond pulsed electric field (nsPEF) has emerged as a promising approach for inducing cell death in melanoma, either as a standalone treatment or in combination with chemotherapeutics. However, to date, there has been a shortage of studies exploring the impact of nsPEF on the expression of cancer-specific molecules. In this investigation, we sought to assess the effects of nsPEF on melanoma-specific MAGE (Melanoma Antigen Gene Protein Family) expression. To achieve this, melanoma cells were exposed to nsPEF with parameters set at 8 kV/cm, 200 ns duration, 100 pulses, and a frequency of 10 kHz. We also aimed to comprehensively describe the consequences of this electric field on melanoma cells' invasion and proliferation potential. Our findings reveal that following exposure to nsPEF, melanoma cells release microvesicles containing MAGE antigens, leading to a simultaneous increase in the expression and mRNA content of membrane-associated antigens such as MAGE-A1. Notably, we observed an unexpected increase in the expression of PD-1 as well. While we did not observe significant differences in the cells' proliferation or invasion potential, a remarkable alteration in the cells' metabolomic and lipidomic profiles towards a less aggressive phenotype was evident. Furthermore, we validated these results using ex vivo tissue cultures and 3D melanoma culture models. Our study demonstrates that nsPEF can elevate the expression of membrane-associated proteins, including melanoma-specific antigens. The mechanism underlying the overexpression of MAGE antigens involves the initial release of microvesicles containing MAGE antigens, followed by a gradual increase in mRNA levels, ultimately resulting in elevated expression of MAGE antigens post-experiment. These findings shed light on a novel method for modulating cancer cells to overexpress cancer-specific molecules, thereby potentially enhancing their sensitivity to targeted anticancer therapy.

Establishment and validation of a gene mutation-based risk model for predicting prognosis and therapy response in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is a malignant clonal proliferative disease of hematopoietic system. Despite tremendous progress in uncovering the AML genome, only a small number of mutations have been incorporated into risk stratification and used as therapeutic targets. In this research, we performed to construct a predictive prognosis risk model for AML patients according to gene mutations.

Methods

Next-generation sequencing (NGS) technology was utilized to detect gene mutation from 118 patients. mRNA expression profiles and related clinical information were mined from TCGA and GEO databases. Consensus cluster analysis was applied to obtain molecular subtypes, and differences in clinicopathological features, prognosis, and immune microenvironment of different clusters were systematically compared. According to the differentially expressed genes (DEGs) between clusters, univariate and LASSO regression analysis were applied to identify gene signatures to build a prognostic risk model. Patients were classified into high-risk (HR) and low-risk (LR) groups according to the median risk score (RS). Differences in prognosis, immune profile, and therapeutic sensitivity between two groups were analyzed. The independent predictive value of RS was assessed and a nomogram was developed.

Results

NGS detected 24 mutated genes, with higher mutation frequencies in CBL (63 %) and SETBP1 (49 %). Two clusters exhibited different immune microenvironments and survival probability (p = 0.0056) were identified. A total of 444 DEGs were screened in two clusters, and a mutation-associated risk model was constructed, including MPO, HGF, SH2B3, SETBP1, HLA-DRB1, LGALS1, and KDM5B. Patients in LR had a superior survival time compared to HR. Predictive performance of this model was confirmed and the developed nomogram further improved the applicability of the risk model with the AUCs for predicting 1-, 3-, 5-year survival rate were 0.829, 0.81 and 0.811, respectively. HR cases were more sensitive to erlotinib, CI-1040, and AZD6244.

Conclusion

These findings supplemented the understanding of gene mutations in AML, and constructed models had good application prospect to provide effective information for predicting prognosis and treatment response of AML.

Acquired immune resistance is associated with interferon signature and modulation of KLF6/c-MYB transcription factors in myeloid leukemia

Resistance to immunity is associated with the selection of cancer cells with superior capacities to survive inflammatory reactions. Here, we tailored an ex vivo immune selection model for acute myeloid leukemia (AML) and isolated the residual subpopulations as "immune-experienced" AML (ieAML) cells. We confirmed that upon surviving the immune reactions, the malignant blasts frequently decelerated proliferation, displayed features of myeloid differentiation and activation, and lost immunogenicity. Transcriptomic analyses revealed a limited number of commonly altered pathways and differentially expressed genes in all ieAML cells derived from distinct parental cell lines. Molecular signatures predominantly associated with interferon and inflammatory cytokine signaling were enriched in the AML cells resisting the T-cell-mediated immune reactions. Moreover, the expression and nuclear localization of the transcription factors c-MYB and KLF6 were noted as the putative markers for immune resistance and identified in subpopulations of AML blasts in the patients' bone marrow aspirates. The immune modulatory capacities of ieAML cells lasted for a restricted period when the immune selection pressure was omitted. In conclusion, myeloid leukemia cells harbor subpopulations that can adapt to the harsh conditions established by immune reactions, and a previous "immune experience" is marked with IFN signature and may pave the way for susceptibility to immune intervention therapies.

Unveiling novel insights in acute myeloid leukemia through single-cell RNA sequencing

Acute myeloid leukemia (AML) is a complex and heterogeneous group of aggressive hematopoietic stem cell disease. The presence of diverse and functionally distinct populations of leukemia cells within the same patient's bone marrow or blood poses a significant challenge in diagnosing and treating AML. A substantial proportion of AML patients demonstrate resistance to induction chemotherapy and a grim prognosis upon relapse. The rapid advance in next generation sequencing technologies, such as single-cell RNA-sequencing (scRNA-seq), has revolutionized our understanding of AML pathogenesis by enabling high-resolution interrogation of the cellular heterogeneity in the AML ecosystem, and their transcriptional signatures at a single-cell level. New studies have successfully characterized the inextricably intertwined interactions among AML cells, immune cells and bone marrow microenvironment and their contributions to the AML development, therapeutic resistance and relapse. These findings have deepened and broadened our understanding the complexity and heterogeneity of AML, which are difficult to detect with bulk RNA-seq. This review encapsulates the burgeoning body of knowledge generated through scRNA-seq, providing the novel insights and discoveries it has unveiled in AML biology. Furthermore, we discuss the potential implications of scRNA-seq in therapeutic opportunities, focusing on immunotherapy. Finally, we highlight the current limitations and future direction of scRNA-seq in the field.

Higher TIGIT+ γδ TCM cells may predict poor prognosis in younger adult patients with non-acute promyelocytic AML

Introduction

γδ T cells recognize and exert cytotoxicity against tumor cells. They are also considered potential immune cells for immunotherapy. Our previous study revealed that the altered expression of immune checkpoint T-cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) on γδ T cells may result in immunosuppression and is possibly associated with a poor overall survival in acute myeloid leukemia (AML). However, whether γδ T-cell memory subsets are predominantly involved and whether they have a relationship with clinical outcomes in patients with AML under the age of 65 remain unclear.

Methods

In this study, we developed a multicolor flow cytometry-based assay to monitor the frequency and distribution of γδ T-cell subsets, including central memory γδ T cells (TCM γδ), effector memory γδ T cells (TEM γδ), and TEM expressing CD45RA (TEMRA γδ), in peripheral blood from 30 young (≤65 years old) patients with newly diagnosed non-acute promyelocytic leukemia (also known as M3) AML (AMLy-DN), 14 young patients with AML in complete remission (AMLy-CR), and 30 healthy individuals (HIs).

Results

Compared with HIs, patients with AMLy-DN exhibited a significantly higher differentiation of γδ T cells, which was characterized by decreased TCM γδ cells and increased TEMRA γδ cells. A generally higher TIGIT expression was observed in γδ T cells and relative subsets in patients with AMLy-DN, which was partially recovered in patients with AMLy-CR. Furthermore, 17 paired bone marrow from patients with AMLy-DN contained higher percentages of γδ and TIGIT+ γδ T cells and a lower percentage of TCM γδ T cells. Multivariate logistic regression analyses revealed the association of high percentage of TIGIT+ TCM γδ T cells with an increased risk of poor induction chemotherapy response.

Conclusions

In this study, we investigated the distribution of γδ T cells and their memory subsets in patients with non-M3 AML and suggested TIGIT+ TCM γδ T cells as potential predictive markers of induction chemotherapy response.

Precision Medicine Approaches in Acute Myeloid Leukemia with Adverse Genetics

The treatment of acute myeloid leukemia (AML) with adverse genetics remains unsatisfactory, with very low response rates to standard chemotherapy and shorter durations of remission commonly observed in these patients. The complex biology of AML with adverse genetics is continuously evolving. Herein, we discuss recent advances in the field focusing on the contribution of molecular drivers of leukemia biogenesis and evolution and on the alterations of the immune system that can be exploited with immune-based therapeutic strategies. We focus on the biological rationales for combining targeted therapy and immunotherapy, which are currently being investigated in ongoing trials, and could hopefully ameliorate the poor outcomes of patients affected by AML with adverse genetics.

Targeting PRMT9-mediated arginine methylation suppresses cancer stem cell maintenance and elicits cGAS-mediated anticancer immunity

Current anticancer therapies cannot eliminate all cancer cells, which hijack normal arginine methylation as a means to promote their maintenance via unknown mechanisms. Here we show that targeting protein arginine N-methyltransferase 9 (PRMT9), whose activities are elevated in blasts and leukemia stem cells (LSCs) from patients with acute myeloid leukemia (AML), eliminates disease via cancer-intrinsic mechanisms and cancer-extrinsic type I interferon (IFN)-associated immunity. PRMT9 ablation in AML cells decreased the arginine methylation of regulators of RNA translation and the DNA damage response, suppressing cell survival. Notably, PRMT9 inhibition promoted DNA damage and activated cyclic GMP-AMP synthase, which underlies the type I IFN response. Genetically activating cyclic GMP-AMP synthase in AML cells blocked leukemogenesis. We also report synergy of a PRMT9 inhibitor with anti-programmed cell death protein 1 in eradicating AML. Overall, we conclude that PRMT9 functions in survival and immune evasion of both LSCs and non-LSCs; targeting PRMT9 may represent a potential anticancer strategy.

The KIR2DL family serves as prognostic biomarkers and correlates with immune infiltrates in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a prevalent haematological malignancy in which various immune and stromal cells in the bone marrow microenvironment have instrumental roles and substantially influence its progression. KIR2DL is a member of the immunoglobulin-like receptor family and a natural killer (NK) cell surface-specific receptor. However, its impact on immune infiltration regarding AML has not been addressed. We aimed to explore molecular markers associated with the immune microenvironment and prognosis of AML with a particular focus on KIR2DL family members. Analysis of data from The Cancer Genome Atlas and Genotype-Tissue Expression databases revealed that KIR2DL1, KIR2DL3 and KIR2DL4 expression were significantly upregulated in AML and associated with decreased overall survival (OS). Moreover, univariate Cox analysis implicated KIR2DL genes as independent prognostic markers of OS. Functional enrichment analysis revealed that KIR2DL genes were associated with immune cells, the immune microenvironment and NK cell-mediated cytotoxicity. Additionally, immune infiltration analyses revealed that KIR2DL upregulation was associated with stronger immune infiltration. Finally, we performed drug sensitivity profiling of KIR2DL genes using the Cellminer database. Collectively, our findings suggest that KIR2DL1, KIR2DL3 and KIR2DL4 have critical roles in AML and may represent novel biomarker genes for disease prognosis and immune infiltration.

Antileukemia Activity of Human Natural Killer Cell-Derived Nanomagic Bullets against Acute Myeloid Leukemia (AML)

Background: Cancer is among the serious health problems of the medical world, for treatment of which severe treatments are used. However, the prognosis of cancer patients is still poor. The application of NK cell-derived exosomes (NK-Exo) is a new method for cancer immunotherapy. These nanoparticles with a size range of 30-120 nm are a small model of mother cells. In this study, the anti-tumor activity of NK-Exo and LAK-Exo (activated NK cell-derived exosome) against acute myeloid leukemia (AML) is investigated in vitro. Materials and Methods: The MACS method was performed for the separation of NK cells from the buffy coats of healthy donors, and an EXOCIBE kit was used for the isolation of NK-Exo. After treating the KG-1 cell line with different doses of NK-Exo, MTT assay, and annexin V-PE were done to evaluate cell proliferation and apoptosis, respectively, and for confirmation of involved proteins, Real-Time PCR and western blotting were performed. Results: Anti-tumor activity of NK-Exo and LAK-Exo was dose- and time-dependent. Their highest activities were observed following 48 hours of incubation with 50 µg/ml exosome (p<0.0001). However, this cytotoxic activity was also seen over a short period of time with low concentrations of NK-Exo (p<0.05) and LAK-Exo (p<0.001).The cytotoxic effect of LAK-Exo on target cells was significantly higher than NK-EXO. The induction of apoptosis by different pathways was time-point dependent. Total apoptosis was 34.56% and 51.6% after 48 hours of tumor cell coculture with 50µg/ml NK-Exo and LAK-Exo, respectively. Significant expression of CASPASE3, P38, and CYTOCHROME C genes was observed in the cells treated with 50 µg/ml NK-Exo and LAK-Exo. Conclusion: Our study confirmed the antileukemia activity of NK-Exo against AML tumor cells in vitro. Therefore, NK-Exo can be considered as a promising and effective treatment for leukemia therapy.

Lactate acid promotes PD-1+ Tregs accumulation in the bone marrow with high tumor burden of Acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) displayed poor response to programmed death-1 (PD-1) blockade therapy. Regulatory T cells (Tregs) was one of major immunosuppressive components in Tumor microenvironment and plays a vital role in the resistance of immunotherapy. Coinhibitory receptors regulate function of regulatory Tregs and are associated with resistance of PD-1 blockade. However, the coinhibitory receptors expression and differentiated status of Tregs in AML patients remain to be unclear.

METHODS

Phenotypic determination of Tregs and CD8+ T cells in bone marrow of healthy donors and AML patients was performed by flow cytometry. Coculture experiments of AML and Tregs in vitro were performed and the concentrations of lactate acid (LA) in the supernatant were examined by ELISA.

RESULTS

More Tregs differentiated into effector subsets in AML patients. However, PD-1 and T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) expression on Tregs were comparable in healthy donors and AML patients. Further analysis showed that PD-1+ and PD-1+TIGIT+Tregs are more abundant in the bone marrow of patients with higher leukemic load. Moreover, PD-1+ Tregs accumulation was associated with higher level of senescent CD4+ T cells and increased frequencies of exhausted CD4+ as well as CD8+ T cells. Notably, neither Tregs nor their effector subsets were decreased among patients in complete remission. PD-1 expression was significantly downregulated in Tregs after achieving complete remission. Mechanistically, both AML cell line (KG-1α) and primary AML blasts produced high concentration of LA. Blockade of LA by lactate transporter inhibitor abrogated the upregulation of PD-1 by AML cells.

CONCLUSION

PD-1+ Tregs accumulation in bone marrow in higher leukemic burden setting was linked to lactate acid secreted by AML blasts and decreased after disease remission. Our findings provided a novel insight into Tregs in AML and possible mechanism for resistance of PD-1 blockade in AML.

The remission status of AML patients after allo-HCT is associated with a distinct single-cell bone marrow T-cell signature

ABSTRACT

Acute myeloid leukemia (AML) is a hematologic malignancy for which allogeneic hematopoietic cell transplantation (allo-HCT) often remains the only curative therapeutic approach. However, incapability of T cells to recognize and eliminate residual leukemia stem cells might lead to an insufficient graft-versus-leukemia (GVL) effect and relapse. Here, we performed single-cell RNA-sequencing (scRNA-seq) on bone marrow (BM) T lymphocytes and CD34+ cells of 6 patients with AML 100 days after allo-HCT to identify T-cell signatures associated with either imminent relapse (REL) or durable complete remission (CR). We observed a higher frequency of cytotoxic CD8+ effector and gamma delta (γδ) T cells in CR vs REL samples. Pseudotime and gene regulatory network analyses revealed that CR CD8+ T cells were more advanced in maturation and had a stronger cytotoxicity signature, whereas REL samples were characterized by inflammatory tumor necrosis factor/NF-κB signaling and an immunosuppressive milieu. We identified ADGRG1/GPR56 as a surface marker enriched in CR CD8+ T cells and confirmed in a CD33-directed chimeric antigen receptor T cell/AML coculture model that GPR56 becomes upregulated on T cells upon antigen encounter and elimination of AML cells. We show that GPR56 continuously increases at the protein level on CD8+ T cells after allo-HCT and confirm faster interferon gamma (IFN-γ) secretion upon re-exposure to matched, but not unmatched, recipient AML cells in the GPR56+ vs GPR56- CD8+ T-cell fraction. Together, our data provide a single-cell reference map of BM-derived T cells after allo-HCT and propose GPR56 expression dynamics as a surrogate for antigen encounter after allo-HCT.

Targeting PRAME for acute myeloid leukemia therapy

Despite significant progress in targeted therapy for acute myeloid leukemia (AML), clinical outcomes are disappointing for elderly patients, patients with less fit disease characteristics, and patients with adverse disease risk characteristics. Over the past 10 years, adaptive T-cell immunotherapy has been recognized as a strategy for treating various malignant tumors. However, it has faced significant challenges in AML, primarily because myeloid blasts do not contain unique surface antigens. The preferentially expressed antigen in melanoma (PRAME), a cancer-testis antigen, is abnormally expressed in AML and does not exist in normal hematopoietic cells. Accumulating evidence has demonstrated that PRAME is a useful target for treating AML. This paper reviews the structure and function of PRAME, its effects on normal cells and AML blasts, its implications in prognosis and follow-up, and its use in antigen-specific immunotherapy for AML.

Exosome-shuttled FTO from BM-MSCs contributes to cancer malignancy and chemoresistance in acute myeloid leukemia by inducing m6A-demethylation: A nano-based investigation

Although bone marrow mesenchymal stem cells (BM-MSCs)-derived exosomes have been reported to be closely associated with acute myeloid leukemia (AML) progression and chemo-resistance, but its detailed functions and molecular mechanisms have not been fully delineated. Besides, serum RNA m6A demethylase fat mass and obesity-associated protein (FTO)-containing exosomes are deemed as important indicators for cancer progression, and this study aimed to investigate the role of BM-MSCs-derived FTO-exosomes in regulating the malignant phenotypes of AML cells. Here, we verified that BM-MSCs-derived exosomes delivered FTO to promote cancer aggressiveness, stem cell properties and Cytosine arabinoside (Ara-C)-chemoresistance in AML cells, and the underlying mechanisms were also uncovered. Our data suggested that BM-MSCs-derived FTO-exo demethylated m6A modifications in the m6A-modified LncRNA GLCC1 to facilitate its combination with the RNA-binding protein Hu antigen R (HuR), which further increased the stability and expression levels of LncRNA GLCC1. In addition, LncRNA GLCC1 was verified as an oncogene to facilitate cell proliferation and enhanced Ara-C-chemoresistance in AML cells. Further experiments confirmed that demethylated LncRNA GLCC1 served as scaffold to facilitate the formation of the IGF2 mRNA binding protein 1 (IGF2BP1)-c-Myc complex, which led to the activation of the downstream tumor-promoting c-Myc-associated signal pathways. Moreover, our rescuing experiments validated that the promoting effects of BM-MSCs-derived FTO-exo on cancer aggressiveness and drug resistance in AML cells were abrogated by silencing LncRNA GLCC1 and c-Myc. Thus, the present firstly investigated the functions and underlying mechanisms by which BM-MSCs-derived FTO-exo enhanced cancer aggressiveness and chemo-resistance in AML by modulating the LncRNA GLCC1-IGF2BP1-c-Myc signal pathway, and our work provided novel biomarkers for the diagnosis, treatment and therapy of AML in clinic.

CD8 + T cell-based molecular subtypes with heterogeneous immune landscapes and clinical significance in acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy. Although high-dose chemotherapy is the primary treatment option, it cannot cure the disease, and new approaches need to be developed. The tumor microenvironment (TME) plays a crucial role in tumor biology and immunotherapy. CD8 + T cells are the main anti-tumor immune effector cells, and it is essential to understand their relationship with the TME and the clinicopathological characteristics of AML.

METHODS

In this study, we conducted a systematic analysis of CD8 + T cell infiltration through multi-omics data and identified molecular subtypes with significant differences in CD8 + T cell infiltration and prognosis. We aimed to provide a comprehensive evaluation of the pathological factors affecting the prognosis of AML patients and to offer theoretical support for the precise treatment of AML.

RESULTS

Our results indicate that CD8 + T cell infiltration is accompanied by immunosuppression, and that there are two molecular subtypes, with the C2 subtype having a significantly worse prognosis than the C1 subtype, as well as less CD8 + T cell infiltration. We developed a signature to distinguish molecular subtypes using multiple machine learning algorithms and validated the prognostic predictive power of molecular subtypes in nine AML cohorts including 2059 AML patients. Our findings suggest that there are different immunosuppressive characteristics between the two subtypes. The C1 subtype has up-regulated expression of immune checkpoints such as CTLA4, PD-1, LAG3, and TIGITD, while the C2 subtype infiltrates more immunosuppressive cells such as Tregs and M2 macrophages. The C1 subtype is more responsive to anti-PD-1 immunotherapy and induction chemotherapy, as well as having higher immune and cancer-promoting variant-related pathway activity. Patients with the C2 subtype had a higher FLT3 mutation rate, higher WBC counts, and a higher percentage of blasts, as indicated by increased activity of signaling pathways involved in energy metabolism and cell proliferation. Analysis of data from ex vivo AML cell drug assays has identified a group of drugs that differ in therapeutic sensitivity between molecular subtypes.

CONCLUSIONS

Our results suggest that the molecular subtypes we constructed have potential application value in the prognosis evaluation and treatment guidance of AML patients.

Nucleic acid therapeutics as differentiation agents for myeloid leukemias

Differentiation therapy has proven to be a success story for patients with acute promyelocytic leukemia. However, the remaining subtypes of acute myeloid leukemia (AML) are treated with cytotoxic chemotherapies that have limited efficacy and a high likelihood of resistance. As differentiation arrest is a hallmark of AML, there is increased interest in developing differentiation-inducing agents to enhance disease-free survival. Here, we provide a comprehensive review of current reports and future avenues of nucleic acid therapeutics for AML, focusing on the use of targeted nucleic acid drugs to promote differentiation. Specifically, we compare and discuss the precision of small interfering RNA, small activating RNA, antisense oligonucleotides, and aptamers to modulate gene expression patterns that drive leukemic cell differentiation. We delve into preclinical and clinical studies that demonstrate the efficacy of nucleic acid-based differentiation therapies to induce leukemic cell maturation and reduce disease burden. By directly influencing the expression of key genes involved in myeloid maturation, nucleic acid therapeutics hold the potential to induce the differentiation of leukemic cells towards a more mature and less aggressive phenotype. Furthermore, we discuss the most critical challenges associated with developing nucleic acid therapeutics for myeloid malignancies. By introducing the progress in the field and identifying future opportunities, we aim to highlight the power of nucleic acid therapeutics in reshaping the landscape of myeloid leukemia treatment.

Benzosceptrin C induces lysosomal degradation of PD-L1 and promotes antitumor immunity by targeting DHHC3

Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blockade has become a mainstay of cancer immunotherapy. Targeting the PD-1/PD-L1 axis with small molecules is an attractive approach to enhance antitumor immunity. Here, we identified a natural marine product, benzosceptrin C (BC), that enhances the cytotoxicity of T cells to cancer cells by reducing the abundance of PD-L1. Furthermore, BC exerts its antitumor effect in mice bearing MC38 tumors by activating tumor-infiltrating T cell immunity. Mechanistic studies suggest that BC can prevent palmitoylation of PD-L1 by inhibiting DHHC3 enzymatic activity. Subsequently, PD-L1 is transferred from the membrane to the cytoplasm and cannot return to the membrane via recycling endosomes, triggering lysosome-mediated degradation of PD-L1. Moreover, the combination of BC and anti-CTLA4 effectively enhances antitumor T cell immunity. Our findings reveal a previously unrecognized antitumor mechanism of BC and represent an alternative immune checkpoint blockade (ICB) therapeutic strategy to enhance the efficacy of cancer immunotherapy.

Machine learning-based investigation of regulated cell death for predicting prognosis and immunotherapy response in glioma patients

Glioblastoma is a highly aggressive and malignant type of brain cancer that originates from glial cells in the brain, with a median survival time of 15 months and a 5-year survival rate of less than 5%. Regulated cell death (RCD) is the autonomous and orderly cell death under genetic control, controlled by precise signaling pathways and molecularly defined effector mechanisms, modulated by pharmacological or genetic interventions, and plays a key role in maintaining homeostasis of the internal environment. The comprehensive and systemic landscape of the RCD in glioma is not fully investigated and explored. After collecting 18 RCD-related signatures from the opening literature, we comprehensively explored the RCD landscape, integrating the multi-omics data, including large-scale bulk data, single-cell level data, glioma cell lines, and proteome level data. We also provided a machine learning framework for screening the potentially therapeutic candidates. Here, based on bulk and single-cell sequencing samples, we explored RCD-related phenotypes, investigated the profile of the RCD, and developed an RCD gene pair scoring system, named RCD.GP signature, showing a reliable and robust performance in predicting the prognosis of glioblastoma. Using the machine learning framework consisting of Lasso, RSF, XgBoost, Enet, CoxBoost and Boruta, we identified seven RCD genes as potential therapeutic targets in glioma and verified that the SLC43A3 highly expressed in glioma grades and glioma cell lines through qRT-PCR. Our study provided comprehensive insights into the RCD roles in glioma, developed a robust RCD gene pair signature for predicting the prognosis of glioma patients, constructed a machine learning framework for screening the core candidates and identified the SLC43A3 as an oncogenic role and a prediction biomarker in glioblastoma.

Identification and immunoassay of prognostic genes associated with the complement system in acute myeloid leukemia

Studies have associated the development of pulmonary leukemia with the activation of the complement system. However, the roles and mechanisms of complement system-related genes (CSRGs) in acute myeloid leukemia (AML) have not been investigated extensively. This study used The Cancer Genome Atlas (TCGA)-AML and GSE37642 datasets. Differentially expressed CSRGs (CSRDEGs) were identified by overlapping genes differentially expressed between the high and low CSRG score groups and key module genes identified in a weighted gene co-expression network analysis. Univariate and multivariate Cox analyses identified CSRG-related biomarkers, which were used to build a prognostic model. After gene set enrichment analysis (GSEA), immune-related and drug-sensitivity analyses were performed in the high- and low-risk groups. Four prognosis-related biomarkers were identified and used to develop a prognostic model: MEOX2, IGFBP5, CH25H, and RAB3B. The model's performance was verified in a test cohort (a subset of samples from the TCGA-AML dataset) and a validation cohort (GSE37642). The GSEA revealed that the high-risk group was mainly enriched for Golgi organization and cytokine-cytokine receptor interactions, and the low-risk group was mainly enriched in the hedgehog signaling pathway and spliceosome. Lastly, two immune cells were found to show differential infiltration between risk groups, which correlated with the risk scores. M1 macrophage infiltration was significantly positively correlated with RAB3B expression. Sensitivity to 36 drugs differed significantly between risk groups. This study screened four CSRG-related biomarkers (MEOX2, IGFBP5, CH25H, and RAB3B) to provide a basis for predicting AML prognosis.

Immunological dynamic characteristics in acute myeloid leukemia predict the long-term outcomes and graft-versus host-disease occurrences post-transplantation

To investigate the relationship between immune dynamic and graft-versus-host-disease (GVHD) risk, 111 initial diagnostic acute myeloid leukemia patients were reviewed. The flow cytometry data of 12 major lymphocyte subsets in bone marrow (BM) from 60 transplant patients at four different time points were analyzed. Additionally, 90 immune subsets in peripheral blood (PB) of 11 post-transplantation on day 100 were reviewed. Our results demonstrated that transplant patients had longer OS compared to non-transplant patients (P < 0.001). Among transplant patients, those who developed GVHD showed longer OS than those without GVHD (P < 0.05). URD donors and CMV-negative status donors were associated with improved OS in transplant patients (P < 0.05). Importantly, we observed a decreased Th/Tc ratio in BM at initial diagnostic in patients with GVHD compared to those without GVHD (P = 0.034). Receiver operating characteristic analysis indicated that a low Th/Tc ratio predicted an increased risk of GVHD with a sensitivity of 44.44% and specificity of 87.50%. Moreover, an increased T/NK ratio in BM of post-induction chemotherapy was found to be associated with GVHD, with a sensitivity of 75.76% and specificity of 65.22%. Additionally, we observed a decreased percentage of NK1 (CD56-CD16+NK) in PB on day 100 post-transplantation in the GVHD group (P < 0.05). These three indicators exhibit promising potential as specific and useful biomarkers for predicting GVHD. These findings provide valuable insights for the early identification and management of GVHD risk, thereby facilitating the possibility of improving patient outcomes.

Dendritic Cells as a Therapeutic Strategy in Acute Myeloid Leukemia: Vaccines

Dendritic cells (DCs) serve as professional antigen-presenting cells (APC) bridging innate and adaptive immunity, playing an essential role in triggering specific cellular and humoral responses against tumor and infectious antigens. Consequently, various DC-based antitumor therapeutic strategies have been developed, particularly vaccines, and have been intensively investigated specifically in the context of acute myeloid leukemia (AML). This hematological malignancy mainly affects the elderly population (those aged over 65), which usually presents a high rate of therapeutic failure and an unfavorable prognosis. In this review, we examine the current state of development and progress of vaccines in AML. The findings evidence the possible administration of DC-based vaccines as an adjuvant treatment in AML following initial therapy. Furthermore, the therapy demonstrates promising outcomes in preventing or delaying tumor relapse and exhibits synergistic effects when combined with other treatments during relapses or disease progression. On the other hand, the remarkable success observed with RNA vaccines for COVID-19, delivered in lipid nanoparticles, has revealed the efficacy and effectiveness of these types of vectors, prompting further exploration and their potential application in AML, as well as other neoplasms, loading them with tumor RNA.

Immunotherapies of acute myeloid leukemia: Rationale, clinical evidence and perspective

Acute myeloid leukemia (AML) is a prevalent hematological malignancy that exhibits a wide array of molecular abnormalities. Although traditional treatment modalities such as chemotherapy and allogeneic stem cell transplantation (HSCT) have become standard therapeutic approaches, a considerable number of patients continue to face relapse and encounter a bleak prognosis. The emergence of immune escape, immunosuppression, minimal residual disease (MRD), and other contributing factors collectively contribute to this challenge. Recent research has increasingly highlighted the notable distinctions between AML tumor microenvironments and those of healthy individuals. In order to investigate the potential therapeutic mechanisms, this study examines the intricate transformations occurring between leukemic cells and their surrounding cells within the tumor microenvironment (TME) of AML. This review classifies immunotherapies into four distinct categories: cancer vaccines, immune checkpoint inhibitors (ICIs), antibody-based immunotherapies, and adoptive T-cell therapies. The results of numerous clinical trials strongly indicate that the identification of optimal combinations of novel agents, either in conjunction with each other or with chemotherapy, represents a crucial advancement in this field. In this review, we aim to explore the current and emerging immunotherapeutic methodologies applicable to AML patients, identify promising targets, and emphasize the crucial requirement to augment patient outcomes. The application of these strategies presents substantial therapeutic prospects within the realm of precision medicine for AML, encompassing the potential to ameliorate patient outcomes.

Immune-driven clonal cell selection at the intersection among cancer, infections, autoimmunity and senescence

Immune surveillance mechanisms play a crucial role in maintaining lifelong immune homeostasis in response to pathologic stimuli and aberrant cell states. However, their persistence, especially in the context of chronic antigenic exposure, can create a fertile ground for immune evasion. These escaping cell phenotypes, harboring a variety of genomic and transcriptomic aberrances, chiefly in human leukocyte antigen (HLA) and antigen presentation machinery genes, may survive and proliferate, featuring a scenario of clonal cell expansion with immune failure characteristics. While well characterized in solid and, to some extent, hematological malignancies, little is known about their occurrence and significance in other disease contexts. Historical literature highlights the role for escaping HLA-mediated recognition as a strategy adopted by virus to evade from the immune system, hinting at the potential for immune aberrant cell expansion in the context of chronic infections. Additionally, unmasked in idiopathic aplastic anemia as a mechanism able to rescue failing hematopoiesis, HLA clonal escape may operate in autoimmune disorders, particularly in tissues targeted by aberrant immune responses. Furthermore, senescent cell status emerging as immunogenic phenotypes stimulating T cell responses, may act as a bottleneck for the selection of such immune escaping clones, blurring the boundaries between neoplastic transformation, aging and inflammation. Here we provide a fresh overview and perspective on this immune-driven clonal cell expansion, linking pathophysiological features of neoplastic, autoimmune, infectious and senescence processes exposed to immune surveillance.

A global bibliometric and visualized analysis of the links between the autophagy and acute myeloid leukemia

Background and objectives: Autophagy is a cellular process where damaged organelles or unwanted proteins are packaged into a double-membrane structure and transported to lysosomes for degradation. Autophagy plays a regulatory role in various hematologic malignancies, including acute myeloid leukemia (AML). However, there are few bibliometric studies on the role of autophagy in AML. The purpose of this study is to clarify the role of autophagy in acute myeloid leukemia through bibliometric analysis. Methods: The literature on autophagy and AML research from 2003 to 2023 was searched in Web of Science Core Collection, and bibliometric tools such as VOSviewer 1.6.18, Cite Space (6.1.R3), RStudio (R package bibliometrix), and Scimago Graphica were used to understand the current status and hotspots of autophagy and AML research. The study conducted an analysis of various dimensions including the quantity of publications, countries, institutions, journals, authors, co-references, keywords, and to predict future development trends in this field by drawing relevant visualization maps. Results: A total of 343 articles were obtained, published in 169 journals, written by 2,323 authors from 295 institutions in 43 countries. The journals with the most publications were Blood and Oncotarget. China had the most publications, and Chongqing Medical University and Sun Yat-sen University had the most publications. The author with the highest number of publications was Tschan, Mario P. The main types of research included clinical research, in vitro experiments, in vivo experiments, public database information, and reviews, and the forms of therapeutic effects mainly focused on genetic regulation, traditional Chinese medicine combination, autophagy inhibitors, and drug targets. The research hotspots of autophagy and AML in the past 17 years have focused on genetic regulation, autophagy inhibition, and targeted drugs. Chemotherapy resistance and mitochondrial autophagy will be the forefront of research. Conclusion: The gradual increase in the literature on autophagy and AML research and the decline after 2022 could be a result of authors focusing more on the type of research and the quality of the literature. The current research hotspots are mainly genetic regulation, autophagy inhibition, and autophagy-related targeted drugs. In future, autophagy will remain the focus of the AML field, with research trends likely to focus more on AML chemotherapy resistance and mitochondrial autophagy.

Immune checkpoint blockade in hematological malignancies: current state and future potential

Malignant cells are known to evade immune surveillance by engaging immune checkpoints which are negative regulators of the immune system. By restoring the T-lymphocyte mediated anti-tumor effect, immune checkpoint inhibitors (ICI) have revolutionized the treatment of solid tumors but have met rather modest success in hematological malignancies. Currently, the only FDA approved indications for ICI therapy are in classic hodgkin lymphoma and primary mediastinal B cell lymphoma. Multiple clinical trials have assessed ICI therapy alone and in combination with standard of care treatments in other lymphomas, plasma cell neoplasms and myeloid neoplasms but were noted to have limited efficacy. These trials mostly focused on PD-1/PDL-1 and CTLA-4 inhibitors. Recently, there has been an effort to target other T-lymphocyte checkpoints like LAG-3, TIM-3, TIGIT along with improving strategies of PD-1/PDL-1 and CTLA-4 inhibition. Drugs targeting the macrophage checkpoint, CD47, are also being tested. Long term safety and efficacy data from these ongoing studies are eagerly awaited. In this comprehensive review, we discuss the mechanism of immune checkpoint inhibitors, the key takeaways from the reported results of completed and ongoing studies of these therapies in the context of hematological malignancies.

Effects of Combinatory In Vitro Treatment with Immune Checkpoint Inhibitors and Cytarabine on the Anti-Cancer Immune Microenvironment in De Novo AML Patients

Despite substantial progress in the diagnostic and therapeutic procedures, acute myeloid leukaemia (AML) still constitutes a significant problem for patients suffering from its relapses. A comprehensive knowledge of the disease's molecular background has led to the development of targeted therapies, including immune checkpoint inhibitors, and demonstrated beneficial effects on several types of cancer. Here, we aimed to assess in vitro the potential of the immune checkpoint blockage for supporting anti-cancer responses to the AML backbone therapy with cytarabine. PBMCs of AML patients were collected at admission and, following the therapy, eight complete remission (CR) and eight non-responders (NR) subjects were selected. We assessed the effects of the in vitro treatment of the cells with cytarabine and the immune checkpoint inhibitors: anti-CTLA-4, anti-PD-1, anti-PD-L1. The study protocol allowed us to evaluate the viability of the cancer and the immune cells, proliferation status, phenotype, and cytokine release. Anti-PD-L1 antibodies were found to exert the most beneficial effect on the activation of T cells, with a concomitant regulation of the immune balance through Treg induction. There was no direct influence on the blast cells; however, the modulation of the PD-1/PD-L1 axis supported the expansion of lymphocytes. Changes in the response between CR and NR patients might result from the differential expression of PD-1 and PD-L1, with lower levels in the latter group. The tested blockers appear to support the anti-cancer immune responses rather than directly improve the effects of cytarabine. In conclusion, checkpoint proteins' modulators might improve the anti-cancer responses in the tumour environment.

Myeloid leukemia-derived galectin-1 downregulates CAR expression to hinder cytotoxicity of CAR T cells

BACKGROUND

Chimeric antigen receptor (CAR) T cells have shown significant activity in B-lineage malignancies. However, their efficacy in myeloid leukemia has not been successful due to unclear molecular mechanisms.

METHODS

We conducted in vitro and in vivo experiments to investigate whether myeloid leukemia cells directly induce CAR down-regulation. Furthermore, we designed a CD33 CARKR in which all lysines in the cytoplasmic domain of CAR were mutated to arginine and verified through in vitro experiments that it could reduce the down-regulation of surface CARs and enhance the killing ability. Transcriptome sequencing was performed on various AML and ALL cell lines and primary samples, and the galectin-1-specific inhibitory peptide (anginex) successfully rescued the killing defect and T-cell activation in in vitro assays.

RESULTS

CAR down-regulation induced by myeloid leukemia cells under conditions of low effector-to-tumor ratio, which in turn impairs the cytotoxicity of CAR T cells. In contrast, lysosomal degradation or actin polymerization inhibitors can effectively alleviate CAR down-regulation and restore CAR T cell-mediated anti-tumor functions. In addition, this study identified galectin-1 as a critical factor used by myeloid leukemia cells to induce CAR down-regulation, resulting in impaired T-cell activation.

CONCLUSION

The discovery of the role of galectin-1 in cell surface CAR down-regulation provides important insights for developing strategies to restore anti-tumor functions.

AMPK activation induces immunogenic cell death in AML

Survival of patients with acute myeloid leukemia (AML) can be improved by allogeneic hematopoietic stem cell transplantation (allo-HSCT) because of the antileukemic activity of T and natural killer cells from the donor. However, the use of allo-HSCT is limited by donor availability, recipient age, and potential severe side effects. Similarly, the efficacy of immunotherapies directing autologous T cells against tumor cells, including T-cell recruiting antibodies, chimeric antigen receptor T-cell therapy, and immune checkpoint inhibitors are limited in AML because of multiple mechanisms of leukemia immune escape. This has prompted a search for novel immunostimulatory approaches. Here, we show that activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), a master regulator of cellular energy balance, by the small molecule GSK621 induces calreticulin (CALR) membrane exposure in murine and human AML cells. When CALR is exposed on the cell surface, it serves as a damage-associated molecular pattern that stimulates immune responses. We found that GSK621-treated murine leukemia cells promote the activation and maturation of bone marrow-derived dendritic cells. Moreover, vaccination with GSK621-treated leukemia cells had a protective effect in syngeneic immunocompetent recipients bearing transplanted AMLs. This effect was lost in recipients depleted of CD4/CD8 T cells. Together, these results demonstrate that AMPK activation by GSK621 elicits traits of immunogenic cell death and promotes a robust immune response against leukemia. Pharmacologic AMPK activation thus represents a new potential target for improving the activity of immunotherapy in AML.

Granulocyte-Macrophage-Colony-Stimulating-Factor Combined with Prostaglandin E1 Create Dendritic Cells of Leukemic Origin from AML Patients' Whole Blood and Whole Bone Marrow That Mediate Antileukemic Processes after Mixed Lymphocyte Culture

Although several (chemotherapeutic) protocols to treat acute myeloid leukemia (AML) are available, high rates of relapses in successfully treated patients occur. Strategies to stabilize remissions are greatly needed. The combination of the (clinically approved) immune-modulatory compounds Granulocyte-Macrophage-Colony-Stimulating-Factor (GM-CSF) and Prostaglandine E1 (PGE-1) (Kit-M) converts myeloid blasts into dendritic cells of leukemic origin (DCleu). After stimulation with DCleu ex vivo, leukemia-specific antileukemic immune cells are activated. Therefore, Kit-M treatment may be an attractive immunotherapeutic tool to treat patients with myeloid leukemia. Kit-M-mediated antileukemic effects on whole bone marrow (WBM) were evaluated and compared to whole blood (WB) to evaluate the potential effects of Kit-M on both compartments. WB and WBM samples from 17 AML patients at first diagnosis, in persisting disease and at relapse after allogeneic stem cell transplantation (SCT) were treated in parallel with Kit-M to generate DC/DCleu. Untreated samples served as controls. After a mixed lymphocyte culture enriched with patients' T cells (MLC), the leukemia-specific antileukemic effects were assessed through the degranulation- (CD107a+ T cells), the intracellular IFNγ production- and the cytotoxicity fluorolysis assay. Quantification of cell subtypes was performed via flow cytometry. In both WB and WBM significantly higher frequencies of (mature) DCleu were generated without induction of blast proliferation in Kit-M-treated samples compared to control. After MLC with Kit-M-treated vs. not pretreated WB or WBM, frequencies of (leukemia-specific) immunoreactive cells (e.g., non-naive, effector-, memory-, CD3+β7+ T cells, NK- cells) were (significantly) increased, whereas leukemia-specific regulatory T cells (Treg, CD152+ T cells) were (significantly) decreased. The cytotoxicity fluorolysis assay showed a significantly improved blast lysis in Kit-M-treated WB and WBM compared to control. A parallel comparison of WB and WBM samples revealed no significant differences in frequencies of DCleu, (leukemia-specific) immunoreactive cells and achieved antileukemic processes. Kit-M was shown to have comparable effects on WB and WBM samples regarding the generation of DCleu and activation of (antileukemic) immune cells after MLC. This was true for samples before or after SCT. In summary, a potential Kit-M in vivo treatment could lead to antileukemic effects in WB as well as WBM in vivo and to stabilization of the disease or remission in patients before or after SCT. A clinical trial is currently being planned.

Cytokine-Induced Memory-Like NK Cells: Emerging strategy for AML immunotherapy

Acute myeloid leukemia (AML) is a heterogeneous disease developed from the malignant expansion of myeloid precursor cells in the bone marrow and peripheral blood. The implementation of intensive chemotherapy and hematopoietic stem cell transplantation (HSCT) has improved outcomes associated with AML, but relapse, along with suboptimal outcomes, is still a common scenario. In the past few years, exploring new therapeutic strategies to optimize treatment outcomes has occurred rapidly. In this regard, natural killer (NK) cell-based immunotherapy has attracted clinical interest due to its critical role in immunosurveillance and their capabilities to target AML blasts. NK cells are cytotoxic innate lymphoid cells that mediate anti-viral and anti-tumor responses by producing pro-inflammatory cytokines and directly inducing cytotoxicity. Although NK cells are well known as short-lived innate immune cells with non-specific responses that have limited their clinical applications, the discovery of cytokine-induced memory-like (CIML) NK cells could overcome these challenges. NK cells pre-activated with the cytokine combination IL-12/15/18 achieved a long-term life span with adaptive immunity characteristics, termed CIML-NK cells. Previous studies documented that using CIML-NK cells in cancer treatment is safe and results in promising outcomes. This review highlights the current application, challenges, and opportunities of CIML-NK cell-based therapy in AML.

Comprehensive analysis of the RSK gene family in acute myeloid leukemia determines a prognostic signature for the prediction of clinical prognosis and treatment responses

OBJECTIVE

The prognosis of acute myeloid leukemia (AML) remains poor although the basic and translational research has been highly productive in understanding the genetics and pathopoiesis of AML and a plethora of targeted therapies have been developed. Consequently, it is crucial to deepen the knowledge of molecular pathogenesis underlying AML for the advancement of new treatment options.

METHOD

A RSK gene family-related signature was constructed to investigate whether RSK gene family members were useful in predicting the prognosis of AML patients. The relationship between the RSK gene family-related signature and the infiltration of immune cells was further assessed using the CIBERSORT algorithm. The 'oncoPredict' package was used to analyze relationships between the RSK gene family-related signature and the sensitivity to drugs or small molecules.

RESULTS

Patients were classified into two groups using the RSK gene family-related signature following the median risk score. Overall survival (OS) was significantly longer in patients with low-risk scores than that in patients with high-risk scores as showed by both training and validation datasets. Moreover, the signature was helpful in predicting 1-year, 3-year, and 5-year OS in training and validation datasets. In addition, it was identified that low-risk patients exhibited greater sensitivity to 20 drugs or small molecules and that high-risk patients had higher sensitivity to 38 drugs or small molecules.

CONCLUSION

RSK gene family members, particularly RPS6KA1 and RPS6KA4, may help to predict prognosis for AML patients. Furthermore, RPS6KA1 may serve as a novel drug target for AML.

A new prognostic risk model for acute myeloid leukemia patients based on telomere-related genes

Telomere maintenance is critical to ensure unlimited cancer cell proliferation, but the role of telomere-related genes in acute myeloid leukemia (AML) has not yet been thoroughly discussed. This study aims to develop a new prognostic risk model based on telomere-related genes and analyze potential mechanisms and targets. Cox regression analyses were used to build the prognostic risk model. Kaplan-Meier (KM) survival analysis and receiver operating characteristic (ROC) curve were used to assess the model performance. At the same time, we analyzed the relationship between the risk score and chemotherapy and immunotherapy and preliminarily explored possible mechanisms of immune resistance. The real-time polymerase chain reaction (PCR) was used to detect the prognosis gene expression levels. Finally, a prognostic signature of six telomere-related genes (TGPS6) including ALDH2, CDK18, DNMT3B, FRAT2, LGALSL, and RBL2 was constructed. The TGPS6 score was confirmed as an independent prognostic factor (HR 2.74, CI [2.13-3.53], p < 0.001) in AML and the five-year area under the ROC curve (AUC) value of the score in the training and validation set reached 0.74, 0.81 respectively. In addition, the TGPS6 perfected the European LeukemiaNet (ELN) 2017 prognosis risk stratification and performed well in both AML and cytogenetically normal AML (CN-AML) cohorts. The TGPS6 score also provided a reference for chemotherapy and immunotherapy in patients with AML.

Immune characteristics and prognostic implications of mucosal-associated invariant T cells in acute myeloid leukemia

Increasing evidence suggests that mucosal-associated invariant T cells (MAITs) play a crucial role in anti-tumor responses against various cancers. In this study, we investigated the immune characteristics of MAIT cells in patients with acute myeloid leukemia (AML). Using multi-parameter flow cytometry, we performed phenotypic and functional analysis of MAITs in peripheral blood or bone marrow samples collected from 131 patients with AML including 99 newly diagnosed, 18 remission, and 14 relapsed cases, as well as 69 healthy controls. We found that MAITs exhibit signs of aging and exhaustion, particularly in CD8+ MAITs subset, at newly diagnosis. MAITs exhibit an effector memory or terminally differentiated phenotype. Frequency and number of MAITs reflect AML cell genetic features, tumor burden, disease status, and treatment responsiveness. Moreover, MAITs exhibit a highly activated or even exhausted state, as indicated by upregulation of PD-1. Furthermore, impaired production of Th1-type cytokines and increased secretion of Th17-type cytokines, granzyme B, and perforin were observed in MAITs from AML patients. Additionally, MAITs shifted toward producing cytokines that promote tumor progression, such as IL-8. Lower frequency of MAITs was associated with poorer overall survival (OS), and multivariate analysis revealed that MAITs frequency < 2.12% was an independent prognostic factor affecting OS. Collectively, our findings suggest that MAITs may play a role in immune deficiency in AML, emphasizing their potential importance in AML pathogenesis and treatment. These discoveries provide a theoretical basis for the development of novel immunotherapeutic strategies in AML.

Identifying prognostic biomarker related to immune infiltration in acute myeloid leukemia

The immune cells of tumor microenvironment (TME) constitute a vital element of the tumor tissue. There is increasing evidence for their clinical significance in predicting prognosis and therapeutic outcomes. However, the TME immune cell infiltrating pattern of the bone marrow in acute myeloid leukemia (AML) patients remains unclear. Here, RNA-sequencing results of AML patients from TCGA database were used to quantify the abundance of 28 types of immune cells in the TME using the single-sample gene set enrichment analysis algorithm. We comprehensively evaluated the immune infiltration status in the TCGA-LAML cohort and defined two immunophenotypes: the immune hot and immune cold subtypes. Additionally, we constructed a TME score reflecting the immune infiltrating pattern of the patients using Cox regression algorithm. Subtypes with high TME score were characterized by over-activation of immune inflammation-related pathways, release of inflammatory factors, T-cell dysfunction, and poor prognosis. Subtypes with a low TME score were characterized by relatively low immune infiltration and immune exclusion. Our analysis indicated that patients in the low TME score group were more sensitive to chemotherapeutic drugs, and those in high TME score were more likely to respond to immunotherapy. Our study provides a new direction to evaluate anti-tumor therapy from immune infiltration of the TME, and the individualized scoring system in this study has important clinical significance in identifying patients who respond to immunotherapy.

Construction of an acute myeloid leukemia prognostic model based on m6A-related efferocytosis-related genes

Background

One of the most prevalent hematological system cancers is acute myeloid leukemia (AML). Efferocytosis-related genes (ERGs) and N6-methyladenosine (m6A) have an important significance in the progression of cancer, and the metastasis of tumors.

Methods

The AML-related data were collected from The Cancer Genome Atlas (TCGA; TCGA-AML) database and Gene Expression Omnibus (GEO; GSE9476, GSE71014, and GSE13159) database. The "limma" R package and Venn diagram were adopted to identify differentially expressed ERGs (DE-ERGs). The m6A related-DE-ERGs were obtained by Spearman analysis. Subsequently, univariate Cox and Least Absolute Shrinkage and Selection Operator (LASSO) were used to construct an m6A related-ERGs risk signature for AML patients. The possibility of immunotherapy for AML was explored. The pRRophetic package was adopted to calculate the IC50 of drugs for the treatment of AML. Finally, the expression of characterized genes was validated by quantitative reverse transcription-PCR (qRT-PCR).

Results

Based on m6A related-DE-ERGs, a prognostic model with four characteristic genes (UCP2, DOCK1, SLC14A1, and SLC25A1) was constructed. The risk score of model was significantly associated with the immune microenvironment of AML, with four immune cell types, 14 immune checkpoints, 20 HLA family genes and, immunophenoscore (IPS) all showing differences between the high- and low-risk groups. A total of 56 drugs were predicted to differ between the two groups, of which Erlotinib, Dasatinib, BI.2536, and bortezomib have been reported to be associated with AML treatment. The qRT-PCR results showed that the expression trends of DOCK1, SLC14A1 and SLC25A1 were consistent with the bioinformatics analysis.

Conclusion

In summary, 4 m6A related- ERGs were identified and the corresponding prognostic model was constructed for AML patients. This prognostic model effectively stratified the risk of AML patients.

Identification and validation of necroptosis-related gene signatures to predict clinical outcomes and therapeutic responses in acute myeloid leukemia

BACKGROUND

Necroptosis is a tightly regulated form of necrotic cell death that promotes inflammation and contributes to disease development. However, the potential roles of necroptosis-related genes (NRGs) in acute myeloid leukemia (AML) have not been elucidated fully.

METHODS

We conducted a study to identify a robust biomarker signature for predicting the prognosis and immunotherapy efficacy based on NRGs in AML. We analyzed the genetic and transcriptional alterations of NRGs in 151 patients with AML. Then, we identified three necroptosis clusters. Moreover, a necroptosis score was constructed and assessed based on the differentially expressed genes (DEGs) between the three necroptosis clusters.

RESULTS

Three necroptosis clusters were correlated with clinical characteristics, prognosis, the tumor microenvironment, and infiltration of immune cells. A high necroptosis score was positively associated with a poor prognosis, immune-cell infiltration, expression of programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1), immune score, stromal score, interferon-gamma (IFNG), merck18, T-cell dysfunction-score signatures, and cluster of differentiation-86, but negatively correlated with tumor immune dysfunction and exclusion score, myeloid-derived suppressor cells, and M2-type tumor-associated macrophages. Our observations indicated that a high necroptosis score might contribute to immune evasion. More interestingly, AML patients with a high necroptosis score may benefit from treatment based on immune checkpoint blockade.

CONCLUSIONS

Consequently, our findings may contribute to deeper understanding of NRGs in AML, and facilitate assessment of the prognosis and treatment strategies.

The diagnostic/prognostic roles and biological function of the IFIT family members in acute myeloid leukemia

BACKGROUND

The Interferon-induced protein with tetratricopeptide repeat (IFIT) family, IFIT1/2/3/5, play an important role in different tumors progression. However, the prognosis significance and biological role of IFIT family members in acute myeloid leukemia (AML) remains unclear.

METHODS

We obtained the gene expression data and clinical information of 173 AML patients from The Cancer Genome Atlas (TCGA) database. Several databases were used in our study, including GEPIA, MethSurv, STRING, GSCA and GeneMANIA database.

RESULTS

The mRNA expression of IFIT1/2/3/5 was elevated in AML patients and had a high ability to distinguish AML from controls based on the receiver operating characteristic (ROC) curve (AUC > 0.9). Kaplan-Meier survival analysis showed that higher levels of IFIT2/3/5 expression predict poor prognosis in AML patients. Besides, the DNA methylation analysis suggested that 7 CpG sites of IFIT2, 4 CpG sites of IFIT3 and 10 CpG sites of IFIT5 were significantly associated with the prognosis of AML patients. In addition, IFIT2/3/5 expression was significantly positively associated with the immune cell infiltration and immune checkpoint expression, such as CTLA4, PDCD1, LAG3, and TIGIT. Finally, drug sensitivity analysis revealed that AML patients with high expression of IFIT2/3/5 were resistant to multiple drugs, but sensitive to dasatinib.

CONCLUSION

IFIT family genes might serve as biomarkers for diagnosis, prognosis and drug sensitivity in AML patients. The activation or blocking of IFIT-related signaling pathways may provide novel insights into immunotherapy for patients with AML.

A novel prognostic classification integrating lipid metabolism and immune co-related genes in acute myeloid leukemia

Background

As a severe hematological malignancy in adults, acute myeloid leukemia (AML) is characterized by high heterogeneity and complexity. Emerging evidence highlights the importance of the tumor immune microenvironment and lipid metabolism in cancer progression. In this study, we comprehensively evaluated the expression profiles of genes related to lipid metabolism and immune modifications to develop a prognostic risk signature for AML.

Methods

First, we extracted the mRNA expression profiles of bone marrow samples from an AML cohort from The Cancer Genome Atlas database and employed Cox regression analysis to select prognostic hub genes associated with lipid metabolism and immunity. We then constructed a prognostic signature with hub genes significantly related to survival and validated the stability and robustness of the prognostic signature using three external datasets. Gene Set Enrichment Analysis was implemented to explore the underlying biological pathways related to the risk signature. Finally, the correlation between signature, immunity, and drug sensitivity was explored.

Results

Eight genes were identified from the analysis and verified in the clinical samples, including APOBEC3C, MSMO1, ATP13A2, SMPDL3B, PLA2G4A, TNFSF15, IL2RA, and HGF, to develop a risk-scoring model that effectively stratified patients with AML into low- and high-risk groups, demonstrating significant differences in survival time. The risk signature was negatively related to immune cell infiltration. Samples with AML in the low-risk group, as defined by the risk signature, were more likely to be responsive to immunotherapy, whereas those at high risk responded better to specific targeted drugs.

Conclusions

This study reveals the significant role of lipid metabolism- and immune-related genes in prognosis and demonstrated the utility of these signature genes as reliable bioinformatic indicators for predicting survival in patients with AML. The risk-scoring model based on these prognostic signature genes holds promise as a valuable tool for individualized treatment decision-making, providing valuable insights for improving patient prognosis and treatment outcomes in AML.

Immunotherapy with Monoclonal Antibodies for Acute Myeloid Leukemia: A Work in Progress

In the last few years, molecularly targeted agents and immune-based treatments (ITs) have significantly changed the landscape of anti-cancer therapy. Indeed, ITs have been proven to be very effective when used against metastatic solid tumors, for which outcomes are extremely poor when using standard approaches. Such a scenario has only been partially reproduced in hematologic malignancies. In the context of acute myeloid leukemia (AML), as innovative drugs are eagerly awaited in the relapsed/refractory setting, different ITs have been explored, but the results are still unsatisfactory. In this work, we will discuss the most important clinical studies to date that adopt ITs in AML, providing the basis to understand how this approach, although still in its infancy, may represent a promising therapeutic tool for the future treatment of AML patients.

Asymmetric anti-CLL-1×CD3 bispecific antibody, ABL602 2+1, with attenuated CD3 affinity endows potent antitumor activity but limited cytokine release

BACKGROUND

Acute myeloid leukemia (AML) is a type of leukemia in adults with a high mortality rate and poor prognosis. Although targeted therapeutics, chemotherapy, and hematopoietic stem cell transplantation can improve the prognosis, the recurrence rate is still high, with a 5-year survival rate of approximately 40%. This study aimed to develop an IgG-based asymmetric bispecific antibody that targets CLL-1 and CD3 for treating AML.

METHODS

ABL602 candidates were compared in terms of binding activity, T-cell activation, and tumor-killing activities. ABL602-mediated T-cell activation and tumor-killing activities were determined by measuring the expression of activation markers, cytokines, cytolytic proteins, and the proportion of dead cells. We evaluated in vivo tumor growth inhibitory activity in two mouse models bearing subcutaneously and orthotopically engrafted human AML. Direct tumor-killing activity and T-cell activation in patient-derived AML blasts were also evaluated.

RESULTS

ABL602 2+1 showed a limited CD3 binding in the absence of CLL-1, suggesting that steric hindrance on the CD3 binding arm could reduce CLL-1 expression-independent CD3 binding. Although the CD3 binding activity was attenuated compared with that of 1+1, ABL602 2+1 exhibited much stronger T-cell activation and potent tumor-killing activities in AML cell lines. ABL602 2+1 efficiently inhibited tumor progression in subcutaneously and orthotopically engrafted AML mouse models. In the orthotopic mouse model, tumor growth inhibition was observed by gross measurement of luciferase activity, as well as a reduced proportion of AML blasts in the bone marrow, as determined by flow cytometry and immunohistochemistry (IHC) staining. ABL602 2+1 efficiently activated T cells and induced the lysis of AML blasts, even at very low effector:target (E:T) ratios (eg, 1:50). Compared with the reference 1+1 antibody, ABL602 did not induce the release of cytokines including interleukin-6 and tumor necrosis factor-α in the healthy donor-derived peripheral blood mononuclear cell.

CONCLUSIONS

With its potent tumor-killing activity and reduced cytokine release, ABL602 2+1 is a promising candidate for treating patients with AML and warrants further study.

Increased TIM-3 and galectin-9 serum levels in patients with advanced systemic mastocytosis

BACKGROUND

Systemic mastocytosis is characterized by expansion of clonal mast cells in various tissues. Several biomarkers with diagnostic and therapeutic potential have recently been characterized in mastocytosis, such as the serum marker tryptase and the immune checkpoint molecule PD-L1.

OBJECTIVE

We aimed to investigate whether serum levels of other checkpoint molecules are altered in systemic mastocytosis and whether these proteins are expressed in mastocytosis infiltrates in the bone marrow.

METHODS

Levels of different checkpoint molecules were analyzed in serum of patients with different categories of systemic mastocytosis and healthy controls and correlated to disease severity. Bone marrow biopsies from patients with systemic mastocytosis were stained to confirm expression.

RESULTS

Serum levels of TIM-3 and galectin-9 were increased in systemic mastocytosis, particularly in advanced subtypes, compared with healthy controls. TIM-3 and galectin-9 levels were also found to correlate with other biomarkers of systemic mastocytosis, such as serum tryptase and KIT D816V variant allele frequency in the peripheral blood. Moreover, we observed expression of TIM-3 and galectin-9 in mastocytosis infiltrates in bone marrow.

CONCLUSIONS

Together, our results demonstrate for the first time that serum levels of TIM-3 and galectin-9 are increased in advanced systemic mastocytosis. Moreover, TIM-3 and galectin-9 are expressed in bone marrow infiltrates in mastocytosis. These findings provide a rationale for exploring TIM-3 and galectin-9 as diagnostic markers and eventually therapeutic targets in systemic mastocytosis, particularly in advanced forms.

STAT5 promotes PD-L1 expression by facilitating histone lactylation to drive immunosuppression in acute myeloid leukemia

Immunotherapy is a revolutionized therapeutic strategy for tumor treatment attributing to the rapid development of genomics and immunology, and immune checkpoint inhibitors have successfully achieved responses in numbers of tumor types, including hematopoietic malignancy. However, acute myeloid leukemia (AML) is a heterogeneous disease and there is still a lack of systematic demonstration to apply immunotherapy in AML based on PD-1/PD-L1 blockage. Thus, the identification of molecules that drive tumor immunosuppression and stratify patients according to the benefit from immune checkpoint inhibitors is urgently needed. Here, we reported that STAT5 was highly expressed in the AML cohort and activated the promoter of glycolytic genes to promote glycolysis in AML cells. As a result, the increased-lactate accumulation promoted E3BP nuclear translocation and facilitated histone lactylation, ultimately inducing PD-L1 transcription. Immune checkpoint inhibitor could block the interaction of PD-1/PD-L1 and reactive CD8+ T cells in the microenvironment when co-culture with STAT5 constitutively activated AML cells. Clinically, lactate accumulation in bone marrow was positively correlated with STAT5 as well as PD-L1 expression in newly diagnosed AML patients. Therefore, we have illustrated a STAT5-lactate-PD-L1 network in AML progression, which demonstrates that AML patients with STAT5 induced-exuberant glycolysis and lactate accumulation may be benefited from PD-1/PD-L-1-based immunotherapy.

Progress of research on PD-1/PD-L1 in leukemia

Leukemia cells prevent immune system from clearing tumor cells by inducing the immunosuppression of the bone marrow (BM) microenvironment. In recent years, further understanding of the BM microenvironment and immune landscape of leukemia has resulted in the introduction of several immunotherapies, including checkpoint inhibitors, T-cell engager, antibody drug conjugates, and cellular therapies in clinical trials. Among them, the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is a significant checkpoint for controlling immune responses, the PD-1 receptor on tumor-infiltrating T cells is bound by PD-L1 on leukemia cells. Consequently, the activation of tumor reactive T cells is inhibited and their apoptosis is promoted, preventing the rejection of the tumor by immune system and thus resulting in the occurrence of immune tolerance. The PD-1/PD-L1 axis serves as a significant mechanism by which tumor cells evade immune surveillance, and PD-1/PD-L1 checkpoint inhibitors have been approved for the treatment of lymphomas and varieties of solid tumors. However, the development of drugs targeting PD-1/PD-L1 in leukemia remains in the clinical-trial stage. In this review, we tally up the basic research and clinical trials on PD-1/PD-L1 inhibitors in leukemia, as well as discuss the relevant toxicity and impacts of PD-1/PD-L1 on other immunotherapies such as hematopoietic stem cell transplantation, bi-specific T-cell engager, chimeric antigen receptor T-cell immunotherapy.

Unveiling T cell evasion mechanisms to immune checkpoint inhibitors in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous and aggressive hematologic malignancy that is associated with a high relapse rate and poor prognosis. Despite advances in immunotherapies in solid tumors and other hematologic malignancies, AML has been particularly difficult to treat with immunotherapies, as their efficacy is limited by the ability of leukemic cells to evade T cell recognition. In this review, we discuss the common mechanisms of T cell evasion in AML: (1) increased expression of immune checkpoint molecules; (2) downregulation of antigen presentation molecules; (3) induction of T cell exhaustion; and (4) creation of an immunosuppressive environment through the increased frequency of regulatory T cells. We also review the clinical investigation of immune checkpoint inhibitors (ICIs) in AML. We discuss the limitations of ICIs, particularly in the context of T cell evasion mechanisms in AML, and we describe emerging strategies to overcome T cell evasion, including combination therapies. Finally, we provide an outlook on the future directions of immunotherapy research in AML, highlighting the need for a more comprehensive understanding of the complex interplay between AML cells and the immune system.