Advances in treating acute myeloid leukemia

DNMT3A-R882: a mutation with many paradoxes

Understanding the underlying mechanism of acute myeloid leukemia (AML) has led to the discovery of novel biomarkers to help predict, treat and monitor leukemia. DNA (cytosine-5)-methyltransferase 3 A (DNMT3A) is considered a prognostic and therapeutic epigenetic target in AML patients with a hotspot mutation of R882. R882 mutation is associated with impaired differentiation of Hematopoietic stem cells in the bone marrow and disease progression. The prevalence of R882 mutation varied in different ethnicities and countries, and similarly, its prognostic impact differed among numerous studies. Nevertheless, the co-occurrence of mutations in R882 with NPM1 and FLT3 has been reported more frequently and is associated with a worse prognosis. These studies also suggest diverse results regarding bone marrow transplantation response as a treatment, while chemoresistance is reached as a conclusive outcome These findings highlight the crucial need for an in-depth discussion on the significance of the R882 mutation in AML patients. Understanding its impact on leukemic transformation, prognosis, and treatment is vital for advancing clinical implications.

WTAP and m6A-modified circRNAs modulation during stress response in acute myeloid leukemia progenitor cells

N6-methyladenosine (m6A) is one of the most prevalent and conserved RNA modifications. It controls several biological processes, including the biogenesis and function of circular RNAs (circRNAs), which are a class of covalently closed-single stranded RNAs. Several studies have revealed that proteotoxic stress response induction could be a relevant anticancer therapy in Acute Myeloid Leukemia (AML). Furthermore, a strong molecular interaction between the m6A mRNA modification factors and the suppression of the proteotoxic stress response has emerged. Since the proteasome inhibition leading to the imbalance in protein homeostasis is strictly linked to the stress response induction, we investigated the role of Bortezomib (Btz) on m6A regulation and in particular its impact on the modulation of m6A-modified circRNAs expression. Here, we show that treating AML cells with Btz downregulated the expression of the m6A regulator WTAP at translational level, mainly because of increased oxidative stress. Indeed, Btz treatment promoted oxidative stress, with ROS generation and HMOX-1 activation and administration of the reducing agent N-acetylcysteine restored WTAP expression. Additionally, we identified m6A-modified circRNAs modulated by Btz treatment, including circHIPK3, which is implicated in protein folding and oxidative stress regulation. These results highlight the intricate molecular networks involved in oxidative and ER stress induction in AML cells following proteotoxic stress response, laying the groundwork for future therapeutic strategies targeting these pathways.

The non-coding competing endogenous RNAs in acute myeloid leukemia: biological and clinical implications

Acute myeloid leukemia (AML) is a hematologic carcinoma that has seen a considerable improvement in patient prognosis because of genetic diagnostics and molecularly-targeted therapies. Nevertheless, recurrence and drug resistance remain significant obstacles to leukemia treatment. It is critical to investigate the underlying molecular mechanisms and find solutions. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), circular RNAs, long non-coding RNAs, and pseudogenes, have been found to be crucial components in driving cancer. The competing endogenous RNA (ceRNA) mechanism has expanded the complexity of miRNA-mediated gene regulation. A great deal of literature has shown that ncRNAs are essential to the biological functions of the ceRNA network (ceRNET). NcRNAs can compete for the same miRNA response elements to influence miRNA-target RNA interactions. Recent evidence suggests that ceRNA might be a potential biomarker and therapeutic strategy. So far, however, there have been no comprehensive studies on ceRNET about AML. What is not yet clear is the clinical application of ceRNA in AML. This study attempts to summarize the development of research on the related ceRNAs in AML and the roles of ncRNAs in ceRNET. We also briefly describe the mechanisms of ceRNA and ceRNET. What's more significant is that we explore the clinical value of ceRNAs to provide accurate diagnostic and prognostic biomarkers as well as therapeutic targets. Finally, limitations and prospects are considered.

Homoharringtonine is synergistically lethal with BCL-2 inhibitor APG-2575 in acute myeloid leukemia

Background

Despite advances in targeted agent development, effective treatment of acute myeloid leukemia (AML) remains a major clinical challenge. The B-cell lymphoma-2 (BCL-2) inhibitor exhibited promising clinical activity in AML, acute lymphoblastic leukemia (ALL) and diffuse large B-cell lymphoma (DLBCL) treatment. APG-2575 is a novel BCL-2 selective inhibitor, which has demonstrated anti-tumor activity in hematologic malignancies. Homoharringtonine (HHT), an alkaloid, exhibited anti-AML activity.

Methods

The synergistic effects of APG-2575 and HHT were studied in AML cell lines and primary samples. MTS was used to measure the cell viability. Annexin V/propidium iodide staining was used to measure the apoptosis rate by flow cytometry. AML cell xenografted mouse models were established to evaluate the anti-leukemic effect of BCL-2 inhibitor, HHT and their combination in vivo. Western blot was used to determine the expression of related proteins.

Results

APG-2575 showed comparable anti-leukemic effect to the FDA-approved BCL-2 inhibitor ABT-199 in vitro and in vivo. Combined treatment of HHT with APG-2575 synergistically inhibited AML cell growth and engraftment. Mechanistically, HHT promoted degradation of myeloid cell leukemia-1 (MCL-1), which was reported to induce BCL-2 inhibitor resistant, through the PI3K/AKT/GSK3β signaling pathway.

Conclusion

Our results provide an effective AML treatment strategy through combination of APG-2575 and HHT, which is worthy of further clinical research.

Expression and prognostic significance of chromatin modulators EHMT2/G9a and KDM2b in acute myeloid leukemia

Epigenetics factors are critical for normal cell function and their regulation is sensitive to malignancy development. EHMT2/G9a and KDM2b are key epigenetics players in different cancer types. However, their expression profiles and related consequences in acute myeloid leukemia (AML) patients have not been known yet. In addition to routine lab work, expression levels of EHMT2/G9a and KDM2b were determined in 110 adult and pediatric patients with De Novo AML. Relations between their expression and patients' clinical data were tested by statistical methods. EHMT2/G9a and KDM2b were highly expressed in AML patients against control cases and associated with the presence of adverse genomic alterations. In response to induction chemotherapy, EHMT2/G9a and KDM2b showed to be significantly high in resistant and relapsed patients in comparison to the complete remission group. KDM2b overexpression was associated with CD11c (integrin alpha X) downregulation. Kaplan-Meier analysis indicated that EHMT2/G9a and KDM2b overexpression was correlated with poor survival status in AML patients. We conclude that EHMT2/G9a and KDM2b expression levels could be used as independent prognostic factors for AML disease.

Identification of mast cells as a candidate significant target of immunotherapy for acute myeloid leukemia

OBJECTION

Immunotherapy based on T cells is a new therapy for Acute myeloid leukemia (AML). However, there has not been considerable improvement compared with traditional chemotherapeutics. This study aimed to identify important immune cells, genes, and drugs associated with the immunotherapy of AML.

METHODS

The gene expression profile and clinical data of patients with AML were downloaded from TCGA database, and the abundance ratio of immune cells was obtained via CIBERSORT. Kaplan-Meier (KM) survival analysis was used to assess the relationship between immune cells and survival time of patients with AML. Differentially expressed genes (DEGs) analysis was conducted to obtained DEGs related to mast cells. Then, protein-protein interaction (PPI) analysis and enrichment analysis were performed to explore the hub genes. Finally, Connectivity Map (CMap) database was utilized to predicts potential drugs that may reverse or induce the mast cell-related gene expression.

RESULTS

Our study showed that mast cell was correlated with survival time of patients with AML, and 135 genes were screened to be related with mast cells. 6 hub genes were identified via PPI network, and 3 potential small molecule drugs were screened to be related to regulating the mast cell-related gene expression via CMap database.

CONCLUSION

The hub genes and drugs have high research value and clinical application in AML therapy. Our study not only provides gene targets and small molecule drugs for AML immunotherapy concerning mast cells but also provides new ideas for researchers to explore immunotherapy targets of other tumors.

Clinical outcome of older adults with acute myeloid Leukemia: An analysis of a large tertiary referral Center over two decades

OBJECTIVE

In older adults with acute myeloid leukemia (AML), the overall outcome is still dismal and long-term data on survival are scarce, particularly outside of clinical trials. Here, we assess characteristics, prognostic factors and long-term survival in patients ≥60 years who were treated for AML at our center over the past 17 years.

METHODS

590 older adults with newly diagnosed AML were characterized according to Eastern Cooperative Oncology Group (ECOG) score, Charlson comorbidity index (CCI), European LeukemiaNet (ELN) risk, type of therapy, serum ferritin (SF) and further baseline characteristics. Survival analysis was performed accordingly.

RESULTS

Median age was 68 years and most patients were in good general condition. Median follow-up was 55.8 months. Of all patients, 66% received intensive chemotherapy (IC) +/- allogeneic hematopoietic stem cell transplantation (allo-HSCT). The remaining cohort received palliative chemotherapy (PC, 26%) or best supportive care only (BSC, 8%). Enrollment rate for interventional clinical trials was 26%. 5-year overall survival (OS) and relapse-free survival (RFS) were 18% (median 12.5 months) and 11,5% (median 10.0 months). Long-term survival was independently influenced by ECOG score, ELN risk group, baseline SF, previous myocardial infarction, and choice of therapy, but not consistently by age or CCI. Considering therapeutic subgroups, the contribution of particular parameters in predicting OS was most compelling in IC patients, but less consistent with PC or BSC.

CONCLUSION

Our results provide thorough insights into prognostication within therapeutic subgroups and emphasize the need for more detailed prognostic algorithms and routine geriatric assessment in the treatment of older adults with AML.

Design of New Therapeutic Agents Targeting FLT3 Receptor Tyrosine Kinase Using Molecular Docking and 3D-QSAR Approach

Background:

FMS-like tyrosine kinase-3 (FLT3) belongs to the class III Receptor Tyrosine Kinase (RTK) family. FLT3 is involved in normal hematopoiesis and is generally expressed in early hematopoietic progenitor cells. Mutations either with an internal tandem duplication of FMS-like tyrosine kinase-3 (FLT3-ITD) or point mutation at the activation loop leads to the Acute Myeloid Leukemia (AML), a highly heterogeneous disease. Thus, FLT3 is an important therapeutic target for AML.

Method:

In the present work, docking and 3D-QSAR techniques were performed on a series of diaminopyrimidine derivatives as FLT3 kinase antagonists.

Results:

Docking study recognized important active site residues such as Leu616, Gly617, Val624, Ala642, Phe830, Tyr693, Cys694, Cys695, Tyr696 and Gly697 that participate in the inhibition of FLT3 kinase. Receptor-based CoMFA, RF-CoMFA and CoMSIA models were developed. RFCoMFA model revealed relatively better statistical results compared to other models. Furthermore, the selected RF-CoMFA model was evaluated using various validation techniques. Contour maps of the RF-CoMFA illustrated that steric and electronegative substitutions were favored at R1 position whereas steric and electropositive substitutions were favored at R2 position to enhance the potency.

Conclusion:

Based on the designed strategy, we derived from the contour map analysis, 14 novel FLT3 inhibitors were designed and their activities were predicted. These designed inhibitors exhibited more potent activity than the most active compounds of the dataset.

Low expression of miR-204 is associated with expression of CD34 and poor performance status in denovo AML

INTRODUCTION

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. There is growing evidence that microRNAs (miRNAs) provide prognostic information in AML. MiR-204 has a tumor suppressor function, and several studies have proven its role in solid cancers. The aim of this work is to evaluate the level of expression of miR-204 in adults newly diagnosed with AML with normal karyotype and to correlate its level of expression with disease outcome and different prognostic factors.

PATIENTS AND METHODS

The study included 87 adult patients newly diagnosed with AML. Detection of miR-204 was done using RT-PCR in patients and seven age-matched controls.

RESULTS

Acute myeloid leukemia patients showed significantly lower miR-204 expression, compared to control group (P = .029). Low miR-204 expression was significantly associated with positive CD34 (P = .017), with poor performance status (PS) (P = .009), and with the presence of diabetes mellitus (DM) (P = .014). Low expression of miR-204 was also significantly associated with shorter overall survival (OS) (P = .020) and disease-free survival (DFS) (P = .013). Low miR-204 expression was identified as an independent prognostic factor for prediction of shorter OS (P = .034) and DFS (P = .027) in AML.

CONCLUSION

To the best of our knowledge; this is the first time to prove the correlation between miR-204 expression and CD34 expression. Further study of this correlation is needed to confirm the role of miR-204 in CD34-positive cells, including leukemic stem cells. This correlation may have therapeutic implications. MiR-204 can be used as a biomarker for PS in AML patients.

A novel circular RNA (hsa_circ_0000370) increases cell viability and inhibits apoptosis of FLT3-ITD-positive acute myeloid leukemia cells by regulating miR-1299 and S100A7A

FLT3-ITD⁺ acute myeloid leukemia (AML) is an important subtype of AML, accounting for approximately 25 % of all AML cases in the world. Recently, increasing evidence has shown that circular RNAs (circRNAs) can act as effective biomarkers of various human cancers. However, the roles of circRNAs in AML remain largely unclear. In the present study, circ_0000370 was found to be significantly increased in FLT3-ITD⁺ AML and was demonstrated to act as an oncogenic circRNA of AML in vitro. TargetScan results showed that miR-1299, miR-370-3p, miR-502-5p, miR-1281 and miR-640 were potential targets of circ_0000370, and miR-1299 had the broadest range of interactome compared with other microRNAs of interest. Moreover, we demonstrated that S100A7A was a target gene of miR-1299, and circ_0000370 could regulate S100A7A expression by sponging miR-1299 in AML cell lines. Therefore, we suggest that the promoting effects of circ_0000370 on the progression of FLT3-ITD⁺ AML might be relevant to the inhibition of miR-1299 and the upregulation of S100A7A.

Single-Chain Variable Fragment-Based Bispecific Antibodies: Hitting Two Targets with One Sophisticated Arrow

Despite the success of monoclonal antibodies (mAbs) to treat some disorders, the monospecific molecular entity of mAbs as well as the presence of multiple factors and pathways involved in the pathogenesis of disorders, such as various malignancies, infectious diseases, and autoimmune disorders, and resistance to therapy have restricted the therapeutic efficacy of mAbs in clinical use. Bispecific antibodies (bsAbs), by concurrently recognizing two targets, can partly circumvent these problems. Serial killing of tumor cells by bsAb-redirected T cells, simultaneous blocking of two antigens involved in the HIV-1 infection, and concurrent targeting of the activating and inhibitory receptors on B cells to modulate autoimmunity are part of the capabilities of bsAbs. After designing and developing a large number of bsAbs for years, catumaxomab, a full-length bsAb targeting EpCAM and CD3, was approved in 2009 to treat EpCAM-positive carcinomas besides blinatumomab, a bispecific T cell engager antibody targeting CD19 and CD3, which was approved in 2014 to treat relapsed or refractory acute lymphoblastic leukemia. Furthermore, approximately 60 bsAbs are under investigation in clinical trials. The current review aims at portraying different formats of the single-chain variable fragment (scFv)-based bsAbs and shedding light on the scFv-based bsAbs in preclinical development, different phases of clinical trials, and the market.

Not Only Mutations Matter: Molecular Picture of Acute Myeloid Leukemia Emerging from Transcriptome Studies

The last two decades of genome-scale research revealed a complex molecular picture of acute myeloid leukemia (AML). On the one hand, a number of mutations were discovered and associated with AML diagnosis and prognosis; some of them were introduced into diagnostic tests. On the other hand, transcriptome studies, which preceded AML exome and genome sequencing, remained poorly translated into clinics. Nevertheless, gene expression studies significantly contributed to the elucidation of AML pathogenesis and indicated potential therapeutic directions. The power of transcriptomic approach lies in its comprehensiveness; we can observe how genome manifests its function in a particular type of cells and follow many genes in one test. Moreover, gene expression measurement can be combined with mutation detection, as high-impact mutations are often present in transcripts. This review sums up 20 years of transcriptome research devoted to AML. Gene expression profiling (GEP) revealed signatures distinctive for selected AML subtypes and uncovered the additional within-subtype heterogeneity. The results were particularly valuable in the case of AML with normal karyotype which concerns up to 50% of AML cases. With the use of GEP, new classes of the disease were identified and prognostic predictors were proposed. A plenty of genes were detected as overexpressed in AML when compared to healthy control, including KIT, BAALC, ERG, MN1, CDX2, WT1, PRAME, and HOX genes. High expression of these genes constitutes usually an unfavorable prognostic factor. Upregulation of FLT3 and NPM1 genes, independent on their mutation status, was also reported in AML and correlated with poor outcome. However, transcriptome is not limited to the protein-coding genes; other types of RNA molecules exist in a cell and regulate genome function. It was shown that microRNA (miRNA) profiles differentiated AML groups and predicted outcome not worse than protein-coding gene profiles. For example, upregulation of miR-10a, miR-10b, and miR-196b and downregulation of miR-192 were found as typical of AML with NPM1 mutation whereas overexpression of miR-155 was associated with FLT3-internal tandem duplication (FLT3-ITD). Development of high-throughput technologies and microarray replacement by next generation sequencing (RNA-seq) enabled uncovering a real variety of leukemic cell transcriptomes, reflected by gene fusions, chimeric RNAs, alternatively spliced transcripts, miRNAs, piRNAs, long noncoding RNAs (lncRNAs), and their special type, circular RNAs. Many of them can be considered as AML biomarkers and potential therapeutic targets. The relations between particular RNA puzzles and other components of leukemic cells and their microenvironment, such as exosomes, are now under investigation. Hopefully, the results of this research will shed the light on these aspects of AML pathogenesis which are still not completely understood.

Inhibition of Wee1 sensitizes AML cells to ATR inhibitor VE-822-induced DNA damage and apoptosis

Resistance to standard induction therapy and relapse remain the primary challenges for improving therapeutic effects in acute myeloid leukemia (AML); thus, novel therapeutic strategies are urgently required. Ataxia telangiectasia and Rad3-related protein (ATR) is a key regulator of different types of DNA damage, which is crucial for the maintenance of genomic integrity. The ATR-selective inhibitor VE-822 has proper solubility, potency, and pharmacokinetic properties. In this study, we investigated the anti-leukemic effects of VE-822 alone or combined with Wee1-selective inhibitor AZD1775 in AML cells. Our results showed that VE-822 inhibited AML cell proliferation and induced apoptosis in a dose-dependent manner. AZD1775 significantly promoted VE-822-induced inhibition of AML cell proliferation and led to a decreased number of cells in the G2/M phase. VE-822 and AZD1775 decreased the protein levels of ribonucleotide reductase M1 (RRM1) and M2 (RRM2) subunits, key enzymes in the synthesis of deoxyribonucleoside triphosphate, which increased DNA replication stress. VE-822 combined with AZD1775 synergistically induced AML cell apoptosis and led to replication stress and DNA damage in AML cell lines. Our study demonstrated that AZD1775 synergistically promotes VE-822-induced anti-leukemic activity in AML cell lines and provides support for clinical research on VE-822 in combination with AZD1775 for the treatment of AML patients.

Antigenic Targets for the Immunotherapy of Acute Myeloid Leukaemia

One of the most promising approaches to preventing relapse is the stimulation of the body’s own immune system to kill residual cancer cells after conventional therapy has destroyed the bulk of the tumour. In acute myeloid leukaemia (AML), the high frequency with which patients achieve first remission, and the diffuse nature of the disease throughout the periphery, makes immunotherapy particularly appealing following induction and consolidation therapy, using chemotherapy, and where possible stem cell transplantation. Immunotherapy could be used to remove residual disease, including leukaemic stem cells from the farthest recesses of the body, reducing, if not eliminating, the prospect of relapse. The identification of novel antigens that exist at disease presentation and can act as targets for immunotherapy have also proved useful in helping us to gain a better understand of the biology that belies AML. It appears that there is an additional function of leukaemia associated antigens as biomarkers of disease state and survival. Here, we discuss these findings.

Acute Myeloid Leukemia: Is That All There Is?

Acute myeloid leukemia (AML) is characterized by the clonal proliferation of malignant myeloid blast cells in the marrow along with impaired normal hematopoiesis. With an almost stagnant approach for the management of patients with AML in the last three decades, the main purpose of this paper is to increase our understanding of recent scientific advancements for the enhanced diagnosis and treatment of AML. Existing research data related to different approaches for a possible improvement in AML management has been collected and discussed. The identification of recurrently mutated genes, such as CCAAT-enhancer-binding proteins α (CEBPα), Fms-related tyrosine kinase 3 (FLT3), and nucleophosmin 1 (NPM1) along with the classic diagnostic karyotype has improved prognostic-risk stratification. Moreover, mutations affecting cellular metabolism like isocitrate dehydrogenase (IDH1), lysine-specific demethylase 1 (LSD 1), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) have become a huge success by providing targets for novel therapeutic drugs. Checkpoint inhibitors (CPI) and vaccination against tumor-associated antigen are added options considered, which require further trials before their efficacy can be determined. An important tool in monitoring early response to therapy, minimal residual disease (MRD) assays can be further refined by including pretreatment parameters such as cytogenetic and molecular markers. Potential side effects and resistance to treatment remains a huge barrier in completely finding success against AML and work needs to be done to find combinations of immunotherapies to possibly reduce adaptive resistance by AML.

Analysis of Candidate Idarubicin Drug Resistance Genes in MOLT-3 Cells Using Exome Nuclear DNA

Various gene alterations related to acute leukemia are reported to be involved in drug resistance. We investigated idarubicin (IDR) resistance using exome nuclear DNA analyses of the human acute leukemia cell line MOLT-3 and the derived IDR-resistant cell line MOLT-3/IDR. We detected mutations in MOLT-3/IDR and MOLT-3 using both Genome Analysis Toolkit (GATK) and SnpEff program. We found 8839 genes with specific mutations in MOLT-3/IDR and 1162 genes with accompanying amino acid mutations. The 1162 genes were identified by exome analysis of polymerase-related genes using Kyoto Encyclopedia of Genes and Genomes (KEGG) and, among these, we identified genes with amino acid changes. In resistant strains, LIG and helicase plurality genes showed amino-acid-related changes. An amino acid mutation was also confirmed in polymerase-associated genes. Gene ontology (GO) enrichment testing was performed, and lipid-related genes were selected from the results. Fluorescent activated cell sorting (FACS) was used to determine whether IDR permeability was significantly different in MOLT-3/IDR and MOLT-3. The results showed that an IDR concentration of 0.5 μg/mL resulted in slow permeability in MOLT-3/IDR. This slow IDR permeability may be due to the effects of amino acid changes in polymerase- and lipid-associated genes.

Pseudogene BMI1P1 expression as a novel predictor for acute myeloid leukemia development and prognosis

The BMI1P1 levels of 144 de novo AML patients and 36 healthy donors were detected by real-time quantitative PCR (RQ-PCR). BMI1P1 was significantly down-regulated in AML compared with control (P < 0.001). A receiver operating characteristic (ROC) curve revealed that BMI1P1 expression could differentiate patients with AML from control subjects (AUC = 0.895, 95% CI: 0.835–0.954, P < 0.001). The percentage of blasts in bone marrow (BM) was significantly lower in BMI1P1 high-expressed group versus low-expressed group (P = 0.008). BMI1P1 high-expressed cases had significantly higher complete remission (CR) than BMI1P1 low-expressed cases (P = 0.023). Furthermore, Kaplan–Meier demonstrated that both whole AML cohort and non-M3-AML patients with low BMI1P1 expression showed shorter leukemia free survival (LFS, P = 0.002 and P = 0.01, respectively) and overall survival (OS, P < 0.001 and P = 0.011, respectively) than those with high BMI1P1 expression. Multivariate analysis also showed that BMI1P1 over-expression was an independent favorable prognostic factor for OS in both whole and non-M3 cohort of AML patients (HR = 0.462, 95% CI = 0.243–0.879, P = 0.019 and HR = 0.483, 95% CI = 0.254–0.919, P = 0.027). To further investigate the significance of BMI1P1 expression in the follow-up of AML patients, we monitored the BMI1P1 level in 26 de novo AML patients and found that the BMI1P1 level increased significantly from the initial diagnosis to post-CR (P < 0.001). These results indicated that BMI1P1 might contribute to the diagnosis of AML and the assessment of therapeutic effect.

Loperamide, an antidiarrheal agent, induces apoptosis and DNA damage in leukemia cells

Loperamide, an antidiarrheal agent, is frequently used to treat patients with leukemia with symptoms of diarrhea during treatment. However, the effect of loperamide on leukemia cells is unknown. The MTT assay was used to explore the cytotoxic effect of loperamide on leukemia cells. Morphological analysis and flow cytometry were performed to determine the level of apoptosis in leukemia cells following loperamide treatment. Western blotting was conducted to test the activation of the apoptotic pathway. The comet assay was used to determine the DNA damage induced by loperamide. Loperamide potently inhibited the proliferation of leukemia cell lines and primary leukemia cells from 9 patients with acute myeloid leukemia (AML) and 6 patients with acute lymphocytic leukemia (ALL) in a dose-dependent manner. Loperamide increased the expression of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase, decreased the expression of myeloid cell lekeumia-1 and induced the apoptosis of leukemia cells. In addition, treatment with 20 µM loperamide increased the expression level of the protein rH2ax and promoted the formation of long DNA comet tails, thus triggering DNA damage in leukemia cells. Finally, DNA damage was confirmed by the activation of the ataxia telangiectasia mutated serine/threonine kinase (ATM)-checkpoint kinase 2 (Chk2) signaling pathway. The phosphorylation level of ATM (Ser1981) and Chk2 (Thr68) was activated and upregulated following DNA damage triggered by loperamide. Loperamide was demonstrated to perform an inhibitory role in the growth of leukemia cell lines and primary leukemia cells. Of note, apoptosis and DNA damage were induced following loperamide treatment in leukemia cell lines and primary leukemia cells.

Efficacy of single-agent decitabine in relapsed and refractory acute myeloid leukemia

Improving therapy for relapsed/refractory AML remains a challenge. We performed a retrospective analysis of outcomes following decitabine treatment in 34 patients with relapsed/refractory AML (median age, 62; median Charlson comorbidity score, 6). Decitabine, 20 mg/m² daily, was given in 5- (25%) or 10-day (75%) cycles. Overall response rate (OR) was 30% with 21% complete remission and 9% partial remission rate. Patients with therapy-related myeloid neoplasm (t-MN) and secondary AML had a significantly higher OR compared to those with de novo AML (70 vs. 30%; p = .02). Median overall survival of all patients was 8.5 months. Median survival in patients with t-MN or secondary AML was 12.4 months compared to 8 months in those with de novo AML (p = .20). Fifteen (44%) patients proceeded to hematopoietic stem cell transplant. These data support using 10-day treatment cycles of decitabine in patients with relapsed/refractory AML, particularly for those with secondary or therapy-related AML.

A novel approach for the identification of efficient combination therapies in primary human acute myeloid leukemia specimens

Appropriate culture methods for the interrogation of primary leukemic samples were hitherto lacking and current assays for compound screening are not adapted for large-scale investigation of synergistic combinations. In this study, we report a novel approach that efficiently distills synthetic lethal interactions between small molecules active on primary human acute myeloid leukemia (AML) specimens. In single-dose experiments and under culture conditions preserving leukemia stem cell activity, our strategy considerably reduces the number of tests needed for the identification of promising compound combinations. Initially conducted with a selected library of 5000 small molecules and 20 primary AML specimens, it reveals 5 broad classes of sensitized therapeutic target pathways along with their synergistic patient-specific fingerprints. This novel method opens new avenues for the development of AML personalized therapeutics and may be generalized to other tumor types, for which in vitro cancer stem cell cultures have been developed.

Oridonin effectively reverses the drug resistance of cisplatin involving induction of cell apoptosis and inhibition of MMP expression in human acute myeloid leukemia cells

Cisplatin is the first generation platinum-based chemotherapy agent. However, the extensive application of cisplatin inevitably causes drug resistance, which is a major obstacle to cancer chemotherapy. Oridonin is a diterpenoid isolated from Rabdosia rubescens with potent anticancer activity. The aim of our study is to investigate the role of oridonin to reverse the cisplatin-resistance in human acute myeloid leukemia (AML) cells. The effect of oridonin on human AML cell proliferation was evaluated by MTT assay, cell migration and invasion were evaluated by transwell migration and invasion assays in cisplatin-resistant human AML cells. Furthermore, cell apoptosis was examined by flow cytometry. The inhibitive effect of oridonin in vivo was determined using xenografted nude mice. In addition, the expressions of MMP2 and MMP9 were detected by Western blot. There was a synergistic antitumor effect between cisplatin and oridonin on cisplatin-resistant human AML cells in vitro and in vivo. In addition, the combination of cisplatin and oridonin synergistically induced cell apoptosis. Furthermore, the combination treatment not only inhibited AML cell migration and invasion, but more significantly, decreased the expressions of MMP2 and MMP9 proteins. Our results suggest that the synergistic effect between both agents is likely to be driven by the inhibition of MMP expression and the resulting increased apoptosis.

Analysis to Estimate Genetic Variations in the Idarubicin-Resistant Derivative MOLT-3

Gene alterations are a well-established mechanism leading to drug resistance in acute leukemia cells. A full understanding of the mechanisms of drug resistance in these cells will facilitate more effective chemotherapy. In this study, we investigated the mechanism(s) of drug resistance in the human acute leukemia cell line MOLT-3 and its idarubicin-resistant derivative MOLT-3/IDR through complete mitochondrial and nuclear DNA analyses. We identified genetic differences between these two cell lines. The ND3 mutation site (p.Thr61Ile) in the mitochondrial DNA sequence was unique to MOLT-3/IDR cells. Moreover, we identified five candidate genes harboring genetic alterations, including GALNT2, via CGH array analysis. Sequencing of the GALNT2 exon revealed a G1716K mutation present within the stop codon in MOLT-3/IDR cells but absent from MOLT-3 cells. This mutation led to an additional 18 amino acids in the protein encoded by GALNT2. Using real-time PCR, we determined an expression value for this gene of 0.35. Protein structure predictions confirmed a structural change in GALNT2 in MOLT-3/IDR cells that corresponded to the site of the mutation. We speculate that this mutation may be related to idarubicin resistance.

An Evaluation of Treatment Patterns and Outcomes in Elderly Patients Newly Diagnosed With Acute Myeloid Leukemia: A Retrospective Analysis of Electronic Medical Records From US Community Oncology Practices

BACKGROUND

Many elderly patients with acute myeloid leukemia (AML) are considered ineligible for standard intensive induction therapy due to performance status and comorbidities. We analyzed treatment patterns and outcomes among elderly patients newly diagnosed with AML in the US community oncology setting.

METHODS

A retrospective observational study was conducted using patient-level data from a network of US community oncology practices provided by Altos Solutions. Patients aged ≥ 60 years, diagnosed with AML between November 2005 and February 2014, with ≥ 1 recorded visit and ≥ 6 months between diagnosis and data cutoff, were included. Only patients who received active treatment or best supportive care (BSC) per National Comprehensive Cancer Network (NCCN) AML Guidelines were analyzed.

RESULTS

Of 1139 patients meeting the inclusion criteria, 922 (median age 76 years) received NCCN-recommended treatments: standard induction (n = 5), low-intensity therapy (n = 425), BSC with hydroxyurea (HU) (n = 36), or BSC without HU (n = 455). For the low-intensity therapy cohort, median time from diagnosis to treatment initiation was 17 days; median duration of therapy was 5.1 months. Median overall survival (OS) from diagnosis in the low-intensity, BSC with HU, and BSC without HU groups was 12.3, 7.0, and 49.4 months, respectively. Median time to next therapy/death was 10.1 months in patients receiving low-intensity therapy. A higher proportion of patients receiving low-intensity therapy required transfusion or other supportive care versus those receiving BSC.

CONCLUSIONS

As expected, OS in patients receiving low-intensity therapy or BSC with HU is poor for elderly patients with AML. Remarkably, intensive induction strategies are rarely used for older patients in community oncology practice.

Superior anti-tumor activity of the MDM2 antagonist idasanutlin and the Bcl-2 inhibitor venetoclax in p53 wild-type acute myeloid leukemia models

Background

Venetoclax, a small molecule BH3 mimetic which inhibits the anti-apoptotic protein Bcl-2, and idasanutlin, a selective MDM2 antagonist, have both shown activity as single-agent treatments in pre-clinical and clinical studies in acute myeloid leukemia (AML). In this study, we deliver the rationale and molecular basis for the combination of idasanutlin and venetoclax for treatment of p53 wild-type AML.

Methods

The effect of idasanutlin and venetoclax combination on cell viability, apoptosis, and cell cycle progression was investigated in vitro using established AML cell lines. In vivo efficacy was demonstrated in subcutaneous and orthotopic xenograft models generated in female nude or non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. Mode-of-action analyses were performed by means of cell cycle kinetic studies, RNA sequencing as well as western blotting experiments.

Results

Combination treatment with venetoclax and idasanutlin results in synergistic anti-tumor activity compared with the respective single-agent treatments in vitro, in p53 wild-type AML cell lines, and leads to strongly superior efficacy in vivo, in subcutaneous and orthotopic AML models. The inhibitory effects of idasanutlin were cell-cycle dependent, with cells arresting in G1 in consecutive cycles and the induction of apoptosis only evident after cells had gone through at least two cell cycles. Combination treatment with venetoclax removed this dependency, resulting in an acceleration of cell death kinetics. As expected, gene expression studies using RNA sequencing showed significant alterations to pathways associated with p53 signaling and cell cycle arrest (CCND1 pathway) in response to idasanutlin treatment. Only few gene expression changes were observed for venetoclax treatment and combination treatment, indicating that their effects are mediated mainly at the post-transcriptional level. Protein expression studies demonstrated that inhibition of the anti-apoptotic protein Mcl-1 contributed to the activity of venetoclax and idasanutlin, with earlier inhibition of Mcl-1 in response to combination treatment contributing to the superior combined activity. The role of Mcl-1 was confirmed by small hairpin RNA gene knockdown studies.

Conclusions

Our findings provide functional and molecular insight on the superior anti-tumor activity of combined idasanutlin and venetoclax treatment in AML and support its further exploration in clinical studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0280-3) contains supplementary material, which is available to authorized users.

Underground Adaptation to a Hostile Environment: Acute Myeloid Leukemia vs. Natural Killer Cells

Acute myeloid leukemia (AML) is a heterogeneous group of malignancies which incidence increases with age. The disease affects the differentiation of hematopoietic stem or precursor cells in the bone marrow and can be related to abnormal cytogenetic and/or specific mutational patterns. AML blasts can be sensitive to natural killer (NK) cell antitumor response. However, NK cells are frequently defective in AML patients leading to tumor escape. NK cell defects affect not only the expression of the activating NK receptors, including the natural cytotoxicity receptors, the NK group 2, member D, and the DNAX accessory molecule-1, but also cytotoxicity and IFN-γ release. Such perturbations in NK cell physiology could be related to the adaptation of the AML to the immune pressure and more generally to patient’s clinical features. Various mechanisms are potentially involved in the inhibition of NK-cell functions in AML, including defects in the normal lymphopoiesis, reduced expression of activating receptors through cell-to-cell contacts, and production of immunosuppressive soluble agents by leukemic blasts. Therefore, the continuous cross-talk between AML and NK cells participates to the leukemia immune escape and eventually to patient’s relapse. Methods to restore or stimulate NK cells seem to be attractive strategies to treat patients once the complete remission is achieved. Moreover, our capacity in stimulating the NK cell functions could lead to the development of preemptive strategies to eliminate leukemia-initiating cells before the emergence of the disease in elderly individuals presenting preleukemic mutations in hematopoietic stem cells.

Allogeneic Hematopoietic Stem Cell Transplantation in FLT3-ITD-Positive Acute Myelogenous Leukemia: The Role for FLT3 Tyrosine Kinase Inhibitors Post-Transplantation

In recent years, allogeneic hematopoietic stem cell transplantation (allo-HSCT) has become increasingly common in patients with acute myelogenous leukemia (AML) due to improved donor availability and the use of nonmyeloablative regimens. However, despite the potential clinical gains with allo-HSCT, the post-transplantation outcomes for many patients, especially those with high-risk disease, remain dismal. Patients with AML who have internal tandem duplication mutations in the tyrosine kinase receptor FLT3 (FLT3-ITD) face particularly poor outcomes, even after allo-HSCT, which appears to only partially mitigate the poor prognosis associated with this mutation. Experimental treatments to reduce the likelihood of relapse and improve survival following allo-HSCT include maintenance with FLT3-specific tyrosine kinase inhibitors (TKIs), several of which are currently being evaluated in clinical studies. Preliminary data and case reports suggest that FLT3 TKIs can be effective in the post-transplantation setting, particularly for patients with FLT3-ITD mutations. Improvements in donor matching, transplantation procedures, and supportive care have allowed a greater number of patients to undergo allo-HSCT than ever before. For these patients, it is essential to identify effective post-transplantation therapies to reduce the risk of relapse and improve disease-free survival.

Prevalence and Prognostic Impact of Wilms' Tumor 1 (WT1) Gene, Including SNP rs16754 in Cytogenetically Normal Acute Myeloblastic Leukemia (CN-AML): An Iranian Experience

BACKGROUND

The aim of this study was to evaluate the effect of Wilms' tumor 1 (WT1) gene mutations in adult cytogenetically normal acute myeloblastic leukemia (CN-AML) patients on survival and clinical outcome.

PATIENTS AND METHODS

A total of 88 untreated Iranian adult patients with CN-AML were selected as a study group. Exons 7 (including the SNP rs16754), 8, and 9 as a WT1 gene hotspot region were evaluated by polymerase chain reaction and direct sequencing for detection of mutations. Response to treatment and clinical outcome including overall survival (OS) and disease-free survival (DFS) were evaluated according to WT1 gene mutational status.

RESULTS

WT1 gene mutations were found in 12.5% of patients, most of which were found in exon 7. Complete remission was lower and relapse was higher in patients with WT1 gene mutation compared with WT1 gene wild type patients. OS and DFS was significantly lower in patients with WT1 gene mutation compared with patients with WT1 gene wild type (P < .001). Also, we did not find any significant effects of SNP rs16754 in exon 7 on clinical outcome and survival in patients with CN-AML.

CONCLUSION

WT1 gene mutations are a predictor indicator of a poor prognosis factor in CN-AML patients. It is recommended that WT1 gene mutations be included in the molecular testing panel in order to better diagnose and confirm their prognostic significance for better management and treatment strategy.

Influence of Bone Marrow Microenvironment on Leukemic Stem Cells: Breaking Up an Intimate Relationship

The bone marrow microenvironment (BMM) plays a critical role in hematopoietic stem cells (HSCs) maintenance and regulation. There is increasing interest in the role of the BMM in promoting leukemia stem cell (LSC) maintenance, resistance to conventional chemotherapy and targeted therapies, and ultimately disease relapse. Recent studies have enhanced our understanding of how the BMM regulates quiescence, self-renewal, and differentiation of LSC. In this comprehensive review, we discuss recent advances in our understanding of the crosstalk between the BMM and LSC, and the critical signaling pathways underlying these interactions. We also discuss potential approaches to exploit these observations to create novel strategies for targeting therapy-resistant LSC to achieve relapse-free survival in leukemic patients.