Relationship between CXC chemokine receptor 4 expression and prognostic significance in acute myeloid leukemia

Relapse of acute myeloid leukemia after allogeneic stem cell transplantation: immune escape mechanisms and current implications for therapy

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the expansion of immature myeloid cells in the bone marrow (BM) and peripheral blood (PB) resulting in failure of normal hematopoiesis and life-threating cytopenia. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an established therapy with curative potential. Nevertheless, post-transplant relapse is common and associated with poor prognosis, representing the major cause of death after allo-HCT. The occurrence of relapse after initially successful allo-HCT indicates that the donor immune system is first able to control the leukemia, which at a later stage develops evasion strategies to escape from immune surveillance. In this review we first provide a comprehensive overview of current knowledge regarding immune escape in AML after allo-HCT, including dysregulated HLA, alterations in immune checkpoints and changes leading to an immunosuppressive tumor microenvironment. In the second part, we draw the line from bench to bedside and elucidate to what extend immune escape mechanisms of relapsed AML are yet exploited in treatment strategies. Finally, we give an outlook how new emerging technologies could help to improve the therapy for these patients, and elucidate potential new treatment options.

T22-PE24-H6 Nanotoxin Selectively Kills CXCR4-High Expressing AML Patient Cells In Vitro and Potently Blocks Dissemination In Vivo

Despite advances in the development of targeted therapies for acute myeloid leukemia (AML), most patients relapse. For that reason, it is still necessary to develop novel therapies that improve treatment effectiveness and overcome drug resistance. We developed T22-PE24-H6, a protein nanoparticle that contains the exotoxin A from the bacterium Pseudomonas aeruginosa and is able to specifically deliver this cytotoxic domain to CXCR4+ leukemic cells. Next, we evaluated the selective delivery and antitumor activity of T22-PE24-H6 in CXCR4+ AML cell lines and BM samples from AML patients. Moreover, we assessed the in vivo antitumor effect of this nanotoxin in a disseminated mouse model generated from CXCR4+ AML cells. T22-PE24-H6 showed a potent, CXCR4-dependent antineoplastic effect in vitro in the MONO-MAC-6 AML cell line. In addition, mice treated with nanotoxins in daily doses reduced the dissemination of CXCR4+ AML cells compared to buffer-treated mice, as shown by the significant decrease in BLI signaling. Furthermore, we did not observe any sign of toxicity or changes in mouse body weight, biochemical parameters, or histopathology in normal tissues. Finally, T22-PE24-H6 exhibited a significant inhibition of cell viability in CXCR4high AML patient samples but showed no activity in CXCR4low samples. These data strongly support the use of T22-PE24-H6 therapy to benefit high-CXCR4-expressing AML patients.

Resveratrol and Its Role in the Management of B-Cell Malignancies-A Recent Update

The growing incidence of B cell malignancies globally has prompted research on the pharmacological properties of phytoconstituents in cancer management. Resveratrol, a polyphenolic stilbenoid widely found in nature, has been explored for its anti-inflammatory and antioxidant properties, and promising results from different pre-clinical studies have indicated its potential for management of B cell malignancies. However, these claims must be substantiated by a greater number of clinical trials in diverse populations, in order to establish its safety and efficacy profile. In addition to this, there is a need to explore nanodelivery of this agent, owing to its poor solubility, which in turn may impact its bioavailability. This review aims to offer an overview of the occurrence and pathogenesis of B cell malignancies with a special focus on the inflammatory pathways involved, the mechanism of actions of resveratrol and its pharmacokinetic profile, results from pre-clinical and clinical studies, as well as an overview of the marketed formulations. The authors have also presented their opinion on the various challenges associated with the clinical development of resveratrol and future perspectives regarding therapeutic applications of this agent.

Upregulation of hsa-miR-625-5p Inhibits Invasion of Acute Myeloid Leukemia Cancer Cells through ILK/AKT Pathway

Objective

Acute myeloid leukemia (AML) is characterized by abnormalities of differentiation and growth of primary hematopoietic stem cells (HSCs) in the blood and bone marrow. In many studies, miR-625-5p has been shown to inhibit downstream pathways from affecting the metastasis and invasion of the integrin-linked kinase (ILK) signaling pathway. It has been proved that the expression of miR-625-5p decreases in AML cell lines. This study aimed to investigate the effect of miR-625-5p upregulation on the invasion of KG1 ell line in vitro.

Materials and Methods

In this experimental study, we investigated the impact of upregulation of miR-625-5p on invasion via the ILK/AKT pathway in the KG1 cell line. After transfection using the viral method, the cellular invasion was assessed by invasion assay and the levels of miR-625-5p genes and protein were evaluated by quantitative polymerase chain reaction (qPCR) and western blotting. Moreover, CXCR4 level was assessed by flow cytometry.

Results

The invasion significantly reduced in MiR-625-5p-transfected KG1 cells (P<0.01) that was concomitant with remarkably decreasing in the expression levels of ILK, NF-κB, and COX2 genes compare with the control group (P<0.01). Incontrast, MMP9, AP1, and AKT significantly increased (P<0.01, P<0.001 and P<0.01, respectively) and GSK3β did not change significantly in MiR-625-5p-transfected KG1 cells. The protein level of NF-κB decreased (P<0.01) and MMP9 increased, however it was not significant. Moreoever, the expression of CXCR4 was significantly lower (P<0.01) in comparison with the control group.

Conclusion

miR-625-5p leads to a reduction in cell invasion in the AML cell line through ILK pathway. Therefore, it could be a breakthrough in future AML-related research. However, further studies are needed to support this argument.

Acute Myeloid Leukemia Mutations and Future Mechanistic Target to Overcome Resistance

OPINION STATEMENT

Cytogenetics and mutation identification in acute myeloid leukemia have allowed for more targeted therapy. Many therapies have been approved by the FDA in the last 3 years including gilteritinib and azacitidine but the overall survival has remained stagnant at 25%. The inability to achieve complete remission was related to the residual leukemic stem cells (LSCs). Thus, the relationship between bone marrow niche and LSCs must be further explored to prevent treatment relapse/resistance. The development of immunotherapy and nanotechnology may play a role in future therapy to achieve the complete remission. Nano-encapsulation of drugs can improve drugs' bioavailability, help drugs evade resistance, and provide combination therapy directly to the cancer cells. Studies indicate targeting surface antigens such as CLL1 and CD123 using chimeric antibody receptor T cells can improve survival outcomes. Finally, new discoveries indicate that inhibiting integrin αvβ3 and acid ceramidase may prove to be efficacious.

Association of SDF-1 Gene Polymorphism with Increased Risk of Acute Myeloid Leukemia Patients

Background:

Acute myeloid leukemia (AML) is a heterogenous group of disorders that emerge from the malignant transformation of hematopoietic stem cells. Chemokine stromal cell-derived factor 1(SDF-1) and its receptor CXC receptor 4 (CXCR4) has an essential role in dissemination of blast cells. Study aimed to detect CXCR4 expression and the SDF-1 (rs1801157) gene polymorphisms and correlate them with prognosis and outcome in AML patients.

Subjects and Methods:

The study was conducted on 60 de-novo AML patients, and 60 healthy controls. SDF-1 (rs1801157) gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and CXCR4 expression was done using flow cytometry analysis.

Results:

SDF-1 dominant model (AG+AA) had higher risk AML (p 0.002). CXCR4 positive cases were associated significantly with toxic manifestations (p 0.019), lower CR rates (p 0.004), and unfavorable cytogenetics (p 0.027). Multivariate analysis showed that combined CXCR4positive with dominant SDF-1 considered as independent prognostic factor for shorter overall survival (OS) in AML patients (p 0.031).

Conclusion:

SDF-1 dominant model had a higher risk to develop AML, and CXCR4 positive expression predicts poor prognosis in AML patients and it could represent a targeted therapy in AML. In addition, CXCR4 could be easily integrated into the initial routine diagnostic work up of AML.

Chemokine receptor CXCR4: An important player affecting the molecular-targeted drugs commonly used in hematological malignancies

INTRODUCTION

A variety of molecular-targeted drugs have been widely used in hematological malignancies and have shown great advances. Nevertheless, as the use of drugs in clinical practice increases, the problem of relapse or of the disease being refractory to treatment is becoming apparent. This problem is closely related to the C-X-C chemokine receptor 4 (CXCR4).

AREAS COVERED

This review focuses mainly on the effect of CXCR4 on molecular-targeted drug resistance in hematological malignancies as well as the clinical efficacy of CXCR4 antagonists combined with molecular-targeted drugs. Relevant literatures published between 2006 and 2020 were searched using PubMed/Medline for this review.

EXPERT OPINION

Monoclonal antibodies and non-antibody molecular-targeted drugs provide new therapeutic approaches for B-lineage malignancies and leukemia, but the clinical activity of these drugs is affected by CXCR4. In general, high CXCR4 expression or mutation inhibits the effects of molecular-targeted drugs, but there are exceptions, and in studies of proteasome inhibitors bortezomib (Bz) in multiple myeloma (MM), low CXCR4 expression or loss of CXCR4 was associated with Bz resistance (BzR) and poor treatment outcomes. Given that CXCR4 is a critical mediator of molecular-targeted drug resistance, numerous studies have combined molecular-targeted drugs with CXCR4 antagonists, which synergistically enhance the anti-proliferative/pro-apoptotic effect of molecular-targeted drugs.

Targeting CXCR4 in AML and ALL

The interaction of acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) blasts with the bone marrow microenvironment regulates self-renewal, growth signaling, as well as chemotherapy resistance. The chemokine receptor, CXC receptor 4 (CXCR4), with its ligand chemokine ligand 12 (CXCL12), plays a key role in the survival and migration of normal and malignant stem cells to the bone marrow. High expression of CXCR4 on AML and ALL blasts has been shown to be a predictor of poor prognosis for these diseases. Several small molecule inhibitors, short peptides, antibodies, and antibody drug conjugates have been developed for the purposes of more effective targeting and killing of malignant cells expressing CXCR4. In this review we will discuss recent results and strategies in targeting CXCR4 with these agents in patients with AML or ALL.

Association between the Wilms tumor-1 rs16754 polymorphism and acute myeloid leukemia: A MOOSE-compliant meta-analysis

The Wilms tumor-1 (WT1) protein is an important regulator of malignant hematopoiesis and has been implicated in the pathogenesis of acute myeloid leukemia (AML). Recently special attention has been paid to the relationship of the WT1 single nucleotide polymorphism (SNP) rs16754 with AML risk and outcome, but the conflicting results made it difficult to draw definitive conclusions. In the present study, we systematically reviewed the literature and performed a meta-analysis of existing evidence. We searched Embase, Pubmed, Web of Science, Medline, Cochrane Library, Wanfang, and China National Knowledge Infrastructure databases using predefined search methodology for relevant studies. We pooled odd ratio (OR) with 95% confidence intervals (95% CI) to evaluate the association between SNP rs16754 and AML risk. In addition, we analyzed hazard ratio (HR) with 95% CI for overall survive, relapse-free survival, and disease-free survival. Q-statistic was used to assess the homogeneity and Egger test was used to evaluate publication bias. Eleven studies met the inclusion criteria for analysis. The results of fixed-effect meta-analyses revealed no association between SNP rs16754 and AML risk (AA + GA vs GG: OR = 0.92, 95% CI: 0.71-1.19, P = .518; AA vs GA + GG: OR = 1.23, 95% CI: 0.86-1.76, P = .262; AA vs GG: OR = 1.05, 95% CI: 0.68-1.63, P = .820; AG vs AA: OR = 0.77, 95% CI: 0.53-1.13, P = .186; AG vs GG: OR = 0.89, 95% CI: 0.68-1.16, P = .376). In subgroup analysis by race, age, and disease type, we did not find any significant association. However, the presence of rs16754 GA/GG genotype was associated with improved overall survive (HR = 0.48, 95% CI: 0.26-0.91, P = .024) and relapse-free survival (HR = 0.82, 95% CI: 0.68-1.00, P = .048) compared with the rs16754 AA. In summary, the WT1 SNP rs16754 was not associated with AML risk, but it had a significant impact on clinical outcome in AML patients.

Location First: Targeting Acute Myeloid Leukemia Within Its Niche

Despite extensive research and development of new treatments, acute myeloid leukemia (AML)-backbone therapy has remained essentially unchanged over the last decades and is frequently associated with poor outcomes. Eradicating the leukemic stem cells (LSCs) is the ultimate challenge in the treatment of AML. Emerging evidence suggests that AML remodels the bone marrow (BM) niche into a leukemia-permissive microenvironment while suppressing normal hematopoiesis. The mechanism of stromal-mediated protection of leukemic cells in the BM is complex and involves many adhesion molecules, chemokines, and cytokines. Targeting these factors may represent a valuable approach to complement existing therapies and overcome microenvironment-mediated drug resistance. Some strategies for dislodging LSCs and leukemic blasts from their protective niche have already been tested in patients and are in different phases of the process of clinical development. Other strategies, such as targeting the stromal cells remodeling processes, remain at pre-clinical stages. Development of humanized xenograft mouse models, which overcome the mismatch between human leukemia cells and the mouse BM niche, is required to generate physiologically relevant, patient-specific human niches in mice that can be used to unravel the role of human AML microenvironment and to carry out preclinical studies for the development of new targeted therapies.