Targeting the Tumor Microenvironment in Acute Myeloid Leukemia: The Future of Immunotherapy and Natural Products

Construction of a stromal-related prognostic model in acute myeloid leukemia by comprehensive bioinformatics analysis

BACKGROUND

Stromal cells play a pivotal role in the tumor microenvironment (TME), significantly impacting the progression of acute myeloid leukemia (AML). This study sought to develop a stromal-related prognostic model for AML, aiming to uncover novel prognostic markers and therapeutic targets.

METHODS

RNA expression data and clinical profiles of AML patients were retrieved from the Cancer Genome Atlas (TCGA). The extent of stromal cell infiltration within the TME was quantified using the ESTIMATE algorithm. Associations between stromal scores and the French-American-British (FAB) classification, overall survival (OS), and the Cancer and Leukemia Group B (CALGB) cytogenetic risk categories were analyzed. Differentially expressed genes (DEGs) were identified, and gene ontology (GO) and protein-protein interaction (PPI) networks were constructed. Prognostic DEGs were selected through LASSO-cox regression analysis. A risk score model was then developed based on these DEGs. A stromal-related prognostic model (SPM) was constructed from the patients' risk scores (RS), and its efficacy was evaluated using Receiver Operating Characteristic (ROC) curves and a nomogram. The association between FAB, CALGB, age, and common mutations and SPM was also assessed. Ultimately, the SPM was validated using an external dataset from 246 patients in the TARGET-AML study.

RESULTS

Kaplan-Meier analysis revealed a significant association between stromal scores and patient survival (p = 0.04). LASSOCox regression identified four genes (MAP7D2, CDRT1, HOXB9, and IRX5) as highly predictive of survival. The prognostic model showed a strong correlation with overall survival, with higher scores indicating poorer outcomes (p = 1.48e-07). Older patients (over 60 years) faced significantly worse prognoses (p = 0.0055). Although no significant association was found between the SPM and the FAB classification (p = 0.063), both poor and intermediate/normal cytogenetic groups had significantly higher SPM risk scores than the favorable group (p = 0.0057 and 0.0026). External validation of the SPM in the TARGET-AML dataset confirmed a significant association with survival (p = 0.00035), with the area under the curve (AUC) for 10-year survival at 75.81 %.

CONCLUSION

Our research successfully established a stromal-related prognostic model in AML, offering new perspectives for prognostic evaluation and identifying potential targets for therapeutic intervention.

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

PURPOSE OF STUDY

Despite the various therapeutic options introduced for AML treatment, therapy resistance and relapse are still the main obstacles. It is well known that alterations in the bone marrow microenvironment (BMM) play a crucial role in leukemia growth and the treatment failure of AML. Evidence shows that exosomes alter the components of BMM in a way that support leukemia survival, leading to chemoresistance. In this study, we evaluated the effect of AML exosomes on the biological functions of human bone marrow mesenchymal stromal cells (h BM-MSCs), especially alteration in the expression of the JAK/STAT signaling genes, as a leukemia-favoring pathway.

METHOD

Exosomes were isolated from the HL-60 cell line and characterized using flow cytometry, Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) technique. The exosome protein content was assessed using a bicinchoninic acid (BCA) protein assay kit in order to determine the concentration of exosomes. Subsequently, MSCs were treated with varying concentrations of AML exosomes, and data was obtained using MTT, cell cycle, apoptosis, and ki67 assays. Additionally, gene expression analysis was conducted through qRT-PCR.

RESULT

AML exosomes regulated the viability and survival of MSCs in a concentration-dependent manner. The qRT-PCR data revealed that treatment with AML exosomes at a concentration of 50 μg/mL led to a significant upregulation of JAK2, STAT3, and STAT5 genes in MSCs.

CONCLUSION

Because the JAK/STAT signaling pathway has been shown to play a role in the proliferation and survival of leukemic cells, our results suggest that AML exosomes stimulate MSCs to activate this pathway. This activation may impede AML cell apoptosis, potentially leading to chemoresistance and relapse.

Evolving strategies to overcome barriers in CAR-T cell therapy for acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) is a complex and heterogeneous disease characterized by an aggressive clinical course and limited efficacious treatment options in the relapsed/refractory (R/R) setting. Chimeric antigen receptor (CAR)-modified T (CAR-T) cell immunotherapy is an investigational treatment strategy for R/R AML that has shown some promise. However, obstacles to successful CAR-T cell immunotherapy for AML remain.

AREAS COVERED

In analyses of clinical trials of CAR-T cell therapy for R/R AML, complete responses without measurable residual disease have been reported, but the durability of those responses remains unclear. Significant barriers to successful CAR-T cell therapy in AML include the scarcity of suitable tumor-target antigens (TTA), inherent T cell functional deficits, and the immunoinhibitory and hostile tumor microenvironment (TME). This review will focus on these barriers to successful CAR-T cell therapy in AML, and discuss scientific advancements and evolving strategies to overcome them.

EXPERT OPINION

Achieving durable remissions in R/R AML will likely require a multifaceted approach that integrates advancements in TTA selection, enhancement of the intrinsic quality of CAR-T cells, and development of strategies to overcome inhibitory mechanisms in the AML TME.

Macrophages as Potential Therapeutic Targets in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogenous malignant hemopathy, and although new drugs have emerged recently, current treatment options still show limited efficacy. Therapy resistance remains a major concern due to its contribution to treatment failure, disease relapse, and increased mortality among patients. The underlying mechanisms of resistance to therapy are not fully understood, and it is crucial to address this challenge to improve therapy. Macrophages are immune cells found within the bone marrow microenvironment (BMME), of critical importance for leukemia development and progression. One defining feature of macrophages is their plasticity, which allows them to adapt to the variations in the microenvironment. While this adaptability is advantageous during wound healing, it can also be exploited in cancer scenarios. Thus, clinical and preclinical investigations that target macrophages as a therapeutic strategy appear promising. Existing research indicates that targeting macrophages could enhance the effectiveness of current AML treatments. This review addresses the importance of macrophages as therapeutic targets including relevant drugs investigated in clinical trials such as pexidartinib, magrolimab or bexmarilimab, but also provides new insights into lesser-known therapies, like macrophage receptor with a collagenous structure (MACRO) inhibitors and Toll-like receptor (TLR) agonists.

Development of a Competitive Nutrient-Based T-Cell Immunotherapy Designed to Block the Adaptive Warburg Effect in Acute Myeloid Leukemia

Background: T-cell-based adoptive cell therapies have emerged at the forefront of cancer immunotherapies; however, failed long-term survival and inevitable exhaustion of transplanted T lymphocytes in vivo limits clinical efficacy. Leukemia blasts possess enhanced glycolysis (Warburg effect), exploiting their microenvironment to deprive nutrients (e.g., glucose) from T cells, leading to T-cell dysfunction and leukemia progression. Methods: Thus, we explored whether genetic reprogramming of T-cell metabolism could improve their survival and empower T cells with a competitive glucose-uptake advantage against blasts and inhibit their uncontrolled proliferation. Results: Here, we discovered that high-glucose concentration reduced the T-cell expression of glucose transporter GLUT1 (SLC2A1) and TFAM (mitochondrion transcription factor A), an essential transcriptional regulator of mitochondrial biogenesis, leading to their impaired expansion ex vivo. To overcome the glucose-induced genetic deficiency in metabolism, we engineered T cells with lentiviral overexpression of SLC2A1 and/or TFAM transgene. Multi-omics analyses revealed that metabolic reprogramming promoted T-cell proliferation by increasing IL-2 release and reducing exhaustion. Moreover, the engineered T cells competitively deprived glucose from allogenic blasts and lessened leukemia burden in vitro. Conclusions: Our findings propose a novel T-cell immunotherapy that utilizes a dual strategy of starving blasts and cytotoxicity for preventing uncontrolled leukemia proliferation.

Nanotechnology-assisted combination drug delivery: a progressive approach for the treatment of acute myeloid leukemia

Acute myeloid leukemia (AML), a heterogeneous hematopoietic cancer prevalent in adults, has been a leading cause of leukemia-associated deaths for decades. Despite advancements in understanding its pathology and pharmacological targets, therapeutic strategies have seen minimal change. The standard treatment, combining cytarabine and anthracycline, has persisted, accompanied by challenges such as pharmacokinetic issues and non-specific drug delivery, leading to severe side effects. Nanotechnology offers a promising solution through combination drug delivery. FDA-approved CPX351 (VYXEOS™) a liposomal formulation delivering doxorubicin and cytarabine, exemplifies enhanced therapeutic efficacy. Ongoing research explores various nanocarriers for delivering multiple bioactives, addressing drug targeting, pharmacokinetics and chemoresistance. This review highlights nanotechnology-based combination therapies for the effective management of AML, presenting a potential breakthrough in leukemia.

Establishment and validation of a prognostic immune-related lncRNA risk model for acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is a cancer arising in the bone marrow and is the most common type of adult leukemia. AML has a poor prognosis, and currently, its prognosis evaluation does not include immune status assessment. This study established an immune-related long non-coding RNA (lncRNA) prognostic risk model for AML based on immune lncRNAs screening.

Methods

To construct training and validation cohorts, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) public databases were accessed to obtain gene expression profiles and clinical data. The correlation between lncRNAs and immunity genes was analyzed using the "limma" package, and the immune-related lncRNAs were obtained. Through least absolute shrinkage and selection operator regression, a prognostic model was established with immune-related lncRNAs. Using the median risk score, patients were divided into high- and low-risk groups. The Kaplan-Meier method was used for survival analysis, whereas the accuracy of the risk model was evaluated using time-dependent receiver operating characteristic curves, risk score distribution, survival status, and risk heat maps. We utilized univariate and multivariate Cox regression to examine the association between risk score and clinical variables and AML survival and prognosis.

Results

In the immune-related lncRNA prognostic risk model, the prognosis was better for low-risk than for high-risk patients, indicating risk score of this model as an independent indicator of prognosis. The area under the curve value for 1-, 3-, and 5-year survival of TCGA patients was 0.817, 0.859, and 0.909, respectively, whereas that of GEO patients (of dataset GPL96-GSE37642) was 0.603, 0.652, and 0.624, respectively. Gene set enrichment analysis revealed the enrichment of multiple pathways, such as antigen processing, B-cell receptor signaling pathway, natural killer cell-mediated cytotoxicity, and chemokines, in high-risk patients.

Conclusions

In this study, immune-related lncRNA prognostic risk models effectively predicted AML survival and provided potential treatment targets.

Analysis of prognostic biomarker models and immune microenvironment in acute myeloid leukemia by integrative bioinformatics

BACKGROUND

Acute myeloid leukemia (AML) is a hematological cancer driven on by aberrant myeloid precursor cell proliferation and differentiation. A prognostic model was created in this study to direct therapeutic care.

METHODS

Differentially expressed genes (DEGs) were investigated using the RNA-seq data from the TCGA-LAML and GTEx. Weighted Gene Coexpression Network Analysis (WGCNA) examines the genes involved in cancer. Find the intersection genes and construct the PPI network to discover hub genes and remove prognosis-related genes. A nomogram was produced for predicting the prognosis of AML patients using the risk prognosis model that was constructed using COX and Lasso regression analysis. GO, KEGG, and ssGSEA analysis were used to look into its biological function. TIDE score predicts immunotherapy response.

RESULTS

Differentially expressed gene analysis revealed 1004 genes, WGCNA analysis revealed 19,575 tumor-related genes, and 941 intersection genes in total. Twelve prognostic genes were found using the PPI network and prognostic analysis. To build a risk rating model, RPS3A and PSMA2 were examined using COX and Lasso regression analysis. The risk score was used to divide the patients into two groups, and Kaplan-Meier analysis indicated that the two groups had different overall survival rates. Univariate and multivariate COX studies demonstrated that risk score is an independent prognostic factor. According to the TIDE study, the immunotherapy response was better in the low-risk group than in the high-risk group.

CONCLUSIONS

We eventually selected out two molecules to construct prediction models that might be used as biomarkers for predicting AML immunotherapy and prognosis.

A potential area of use for immune checkpoint inhibitors: Targeting bone marrow microenvironment in acute myeloid leukemia

Acute myeloid leukemia (AML) arises from the cells of myeloid lineage and is the most frequent leukemia type in adulthood accounting for about 80% of all cases. The most common treatment strategy for the treatment of AML includes chemotherapy, in rare cases radiotherapy and stem cell and bone marrow transplantation are considered. Immune checkpoint proteins involve in the negative regulation of immune cells, leading to an escape from immune surveillance, in turn, causing failure of tumor cell elimination. Immune checkpoint inhibitors (ICIs) target the negative regulation of the immune cells and support the immune system in terms of anti-tumor immunity. Bone marrow microenvironment (BMM) bears various blood cell lineages and the interactions between these lineages and the noncellular components of BMM are considered important for AML development and progression. Administration of ICIs for the AML treatment may be a promising option by regulating BMM. In this review, we summarize the current treatment options in AML treatment and discuss the possible application of ICIs in AML treatment from the perspective of the regulation of BMM.

The potential role of the thymus in immunotherapies for acute myeloid leukemia

Understanding the factors which shape T-lymphocyte immunity is critical for the development and application of future immunotherapeutic strategies in treating hematological malignancies. The thymus, a specialized central lymphoid organ, plays important roles in generating a diverse T lymphocyte repertoire during the infantile and juvenile stages of humans. However, age-associated thymic involution and diseases or treatment associated injury result in a decline in its continuous role in the maintenance of T cell-mediated anti-tumor/virus immunity. Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that mainly affects older adults, and the disease's progression is known to consist of an impaired immune surveillance including a reduction in naïve T cell output, a restriction in T cell receptor repertoire, and an increase in frequencies of regulatory T cells. As one of the most successful immunotherapies thus far developed for malignancy, T-cell-based adoptive cell therapies could be essential for the development of a durable effective treatment to eliminate residue leukemic cells (blasts) and prevent AML relapse. Thus, a detailed cellular and molecular landscape of how the adult thymus functions within the context of the AML microenvironment will provide new insights into both the immune-related pathogenesis and the regeneration of a functional immune system against leukemia in AML patients. Herein, we review the available evidence supporting the potential correlation between thymic dysfunction and T-lymphocyte impairment with the ontogeny of AML (II-VI). We then discuss how the thymus could impact current and future therapeutic approaches in AML (VII). Finally, we review various strategies to rejuvenate thymic function to improve the precision and efficacy of cancer immunotherapy (VIII).