Isocitrate dehydrogenase inhibitors in acute myeloid leukemia

An integrative computational approach for the identification of dual inhibitors of isocitrate dehydrogenase 1 and 2 from phytocompounds of Phyllantus amarus

Genetic alterations of the genes encoding the isocitrate dehydrogenase (IDH) enzymes have been identified in about 20% of acute myeloid leukemia (AML) cases as well as many other forms of cancers. Notable among these alterations are the neomorphic IDH1_R132H and IDH2_R140Q mutations which lead to the production of an oncometabolite. Hence, their inhibition is widely considered a therapeutic strategy in the treatment of many cancers. While many inhibitors of the mutant enzymes have been developed, an inhibitor that is capable of co-inhibiting both enzymes are currently lacking while drug resistance has also limited the clinical usage of previously identified mono inhibitors. Consequently, this study employed molecular modeling approaches, such as molecular docking, molecular mechanics generalized Born Surface area (MM/GBSA), molecular dynamics (MD) simulation, and density functional theory (DFT) analysis to identify potential dual inhibitors of the previously mentioned mutant IDH1/2 from the phytocompounds of Phyllantus amarus. Of the 31 phytocompounds identified, 20 showed good binding affinities for both IDH1 _R132H and IDH2 _R140Q (ranging from -5.2 Kca/mol to -9.6 Kcal/mol) and had desirable pharmacokinetic properties. However, ellagic acid and pinoresinol possessed better pharmacokinetic properties, rendering suitable hits. Investigation of the behavior of the IDH1_R132H and IDH2_R140Q complexes with ellagic acid and pinoresinol via the RMSD, RMSF, and contact map analyses showed that all the complexes-maintained stability throughout the simulation time. Ultimately, ellagic acid and pinoresinol were identified as promising hits for the development of IDH1_R132H and IDH2_R140Q dual inhibitors. However, further experimental studies are needed to confirm their potential as therapies.Communicated by Ramaswamy H. Sarma.

Rationale design of novel substituted 1,3,5-triazine candidates as dual IDH1(R132H)/ IDH2(R140Q) inhibitors with high selectivity against acute myeloid leukemia: In vitro and in vivo preclinical investigations

In this study, novel substituted 1,3,5-triazine candidates (4a-d, 5a-j, and 6a-d) were designed as second-generation small molecules to act as dual IDH1 and IDH2 inhibitors according to the pharmacophoric features of both vorasidenib and enasidenib. Compounds 6a and 6b for leukemia cell lines showed from low to sub-micromolar GI50. Moreover, compounds 4c, 5f, and 6b described the frontier antitumor activity against THP1 and Kasumi Leukemia cancer cells with IC50 values of (10 and 12), (10.5 and 7), and (6.2 and 5.9) µg/mL, which were superior to those of cisplatin (25 and 28) µg/mL, respectively. Interestingly, compounds 4c, 6b, and 6d represented the best dual IDH1(R132H)/IDH2(R140Q) inhibitory potentials with IC50 values of (0.72 and 1.22), (0.12 and 0.93), and (0.50 and 1.28) µg/mL, respectively, compared to vorasidenib (0.02 and 0.08) µg/mL and enasidenib (0.33 and 1.80) µg/mL. Furthermore, the most active candidate (6b) has very promising inhibitory potentials towards HIF-1α, VEGF, and SDH, besides, a marked increase of ROS was observed as well. Besides, compound 6b induced the upregulation of P53, BAX, Caspases 3, 6, 8, and 9 proteins by 3.70, 1.99, 2.06, 1.73, 1.75, and 1.85-fold changes, respectively, and the downregulation for the BCL-2 protein by 0.55-fold change compared to the control. Besides, the in vivo behavior of compound 6b as an antitumor agent was evaluated in female mice bearing solid Ehrlich carcinoma tumors. Notably, compound 6b administration resulted in a prominent decrease in the weight and volume of the tumors, accompanied by improvements in biochemical, hematological, and histological parameters.

Lead optimisation of OXS007417: in vivo PK profile and hERG liability modulation to optimise a small molecule differentiation agent for the potential treatment of acute myeloid leukaemia

The development of a safe, efficacious, and widely effective differentiation therapy for AML would dramatically improve the outlook for many patients worldwide. To this aim, our laboratory has discovered a class of differentiation agents that demonstrate tumour regression in murine models in vivo. Herein, we report a lead optimisation process around compound OXS007417, which led to improved potency, solubility, metabolic stability, and off-target toxicity of this compound class. A hERG liability was investigated and successfully alleviated through addition of nitrogen atoms into key positions of the compound. OXS008255 and OXS008474 demonstrated an improved murine PK profile in respect to OXS007417 and a delay in tumour growth in a subcutaneous in vivo model using HL-60 cells.

Mitochondrial bioenergetics as a cell fate rheostat for responsive to Bcl-2 drugs: New cues for cancer chemotherapy

Pro-survival BCL-2 proteins prevent the initiation of intrinsic apoptosis (mitochondria-dependent pathway) by inhibiting the pro-apoptotic proteins BAX and BAK, while BH3-only proteins promote apoptosis by blocking pro-survival BCL-2 proteins. Disruptions in this delicate balance contribute to cancer cell survival and chemoresistance. Recent advances in cancer therapeutics involve a new generation of drugs known as BH3-mimetics, which are small molecules designed to mimic the action of BH3-only proteins. Promising effects have been observed in patients with hematological and solid tumors undergoing treatment with these agents. However, the rapid emergence of mitochondria-dependent resistance to BH3-mimetics has been reported. This resistance involves increased mitochondrial respiration, altered mitophagy, and mitochondria with higher and tighter cristae. Conversely, mutations in isocitrate dehydrogenase 1 and 2, catalyzing R-2-hydroxyglutarate production, promote sensitivity to venetoclax. This evidence underscores the urgency for comprehensive studies on bioenergetics-based adaptive responses in both BH3 mimetics-sensitive and -resistant cancer cells. Ongoing clinical trials are evaluating BH3-mimetics in combination with standard chemotherapeutics. In this article, we discuss the role of mitochondrial bioenergetics in response to BH3-mimetics and explore potential therapeutic opportunities through metabolism-targeting strategies.

Single cell and bulk RNA expression analyses identify enhanced hexosamine biosynthetic pathway and O-GlcNAcylation in acute myeloid leukemia blasts and stem cells

Introduction

Acute myeloid leukemia (AML) is the most common acute leukemia in adults with an overall poor prognosis and high relapse rate. Multiple factors including genetic abnormalities, differentiation defects and altered cellular metabolism contribute to AML development and progression. Though the roles of oxidative phosphorylation and glycolysis are defined in AML, the role of the hexosamine biosynthetic pathway (HBP), which regulates the O-GlcNAcylation of cytoplasmic and nuclear proteins, remains poorly defined.

Methods

We studied the expression of the key enzymes involved in the HBP in AML blasts and stem cells by RNA sequencing at the single-cell and bulk level. We performed flow cytometry to study OGT protein expression and global O-GlcNAcylation. We studied the functional effects of inhibiting O-GlcNAcylation on transcriptional activation in AML cells by Western blotting and real time PCR and on cell cycle by flow cytometry.

Results

We found higher expression levels of the key enzymes in the HBP in AML as compared to healthy donors in whole blood. We observed elevated O-GlcNAc Transferase (OGT) and O-GlcNAcase (OGA) expression in AML stem and bulk cells as compared to normal hematopoietic stem and progenitor cells (HSPCs). We also found that both AML bulk cells and stem cells show significantly enhanced OGT protein expression and global O-GlcNAcylation as compared to normal HSPCs, validating our in silico findings. Gene set analysis showed substantial enrichment of the NF-κB pathway in AML cells expressing high OGT levels. Inhibition of O-GlcNAcylation decreased NF-κB nuclear translocation and the expression of selected NF-κB-dependent genes controlling cell cycle. It also blocked cell cycle progression suggesting a link between enhanced O-GlcNAcylation and NF-κB activation in AML cell survival and proliferation.

Discussion

Our study suggests the HBP may prove a potential target, alone or in combination with other therapeutic approaches, to impact both AML blasts and stem cells. Moreover, as insufficient targeting of AML stem cells by traditional chemotherapy is thought to lead to relapse, blocking HBP and O-GlcNAcylation in AML stem cells may represent a novel promising target to control relapse.

Epigenetic therapeutic strategies in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies, characterized by its aggressiveness and metastatic potential, with a 5-year survival rate of only 8-11%. Despite significant improvements in PDAC treatment and management, therapeutic alternatives are still limited. One of the main reasons is its high degree of intra- and inter-individual tumor heterogeneity which is established and maintained through a complex network of transcription factors and epigenetic regulators. Epigenetic drugs, have shown promising preclinical results in PDAC and are currently being evaluated in clinical trials both for their ability to sensitize cancer cells to cytotoxic drugs and to counteract the immunosuppressive characteristic of PDAC tumor microenvironment. In this review, we discuss the current status of epigenetic treatment strategies to overcome molecular and cellular PDAC heterogeneity in order to improve response to therapy.

Recent advance of clinically approved small-molecule drugs for the treatment of myeloid leukemia

Myeloid leukemia denotes a hematologic malignancy characterized by aberrant proliferation and impaired differentiation of blood progenitor cells within the bone marrow. Despite the availability of several treatment options, the clinical outlook for individuals afflicted with myeloid leukemia continues to be unfavorable, making it a challenging disease to manage. Over the past, substantial endeavors have been dedicated to the identification of novel targets and the advancement of enhanced therapeutic modalities to ameliorate the management of this disease, resulting in the discovery of many clinically approved small-molecule drugs for myeloid leukemia, including histone deacetylase inhibitors, hypomethylating agents, and tyrosine kinase inhibitors. This comprehensive review succinctly presents an up-to-date assessment of the application and synthetic routes of clinically sanctioned small-molecule drugs employed in the treatment of myeloid leukemia. Additionally, it provides a concise exploration of the pertinent challenges and prospects encompassing drug resistance and toxicity. Overall, this review effectively underscores the considerable promise exhibited by clinically endorsed small-molecule drugs in the therapeutic realm of myeloid leukemia, while concurrently shedding light on the prospective avenues that may shape the future landscape of drug development within this domain.

Crosstalk between DNA methylation and hypoxia in acute myeloid leukaemia

BACKGROUND

Acute myeloid leukaemia (AML) is a deadly disease characterised by the uncontrolled proliferation of immature myeloid cells within the bone marrow. Altered regulation of DNA methylation is an important epigenetic driver of AML, where the hypoxic bone marrow microenvironment can help facilitate leukaemogenesis. Thus, interactions between epigenetic regulation and hypoxia signalling will have important implications for AML development and treatment.

MAIN BODY

This review summarises the importance of DNA methylation and the hypoxic bone marrow microenvironment in the development, progression, and treatment of AML. Here, we focus on the role hypoxia plays on signalling and the subsequent regulation of DNA methylation. Hypoxia is likely to influence DNA methylation through altered metabolic pathways, transcriptional control of epigenetic regulators, and direct effects on the enzymatic activity of epigenetic modifiers. DNA methylation may also prevent activation of hypoxia-responsive genes, demonstrating bidirectional crosstalk between epigenetic regulation and the hypoxic microenvironment. Finally, we consider the clinical implications of these interactions, suggesting that reduced cell cycling within the hypoxic bone marrow may decrease the efficacy of hypomethylating agents.

CONCLUSION

Hypoxia is likely to influence AML progression through complex interactions with DNA methylation, where the therapeutic efficacy of hypomethylating agents may be limited within the hypoxic bone marrow. To achieve optimal outcomes for AML patients, future studies should therefore consider co-treatments that can promote cycling of AML cells within the bone marrow or encourage their dissociation from the bone marrow.

A Leukemic Target with a Thousand Faces: The Mitochondria

In the era of personalized medicine greatly improved by molecular diagnosis and tailor-made therapies, the survival rate of acute myeloid leukemia (AML) at 5 years remains unfortunately low. Indeed, the high heterogeneity of AML clones with distinct metabolic and molecular profiles allows them to survive the chemotherapy-induced changes, thus leading to resistance, clonal evolution, and relapse. Moreover, leukemic stem cells (LSCs), the quiescent reservoir of residual disease, can persist for a long time and activate the recurrence of disease, supported by significant metabolic differences compared to AML blasts. All these points highlight the relevance to develop combination therapies, including metabolism inhibitors to improve treatment efficacy. In this review, we summarized the metabolic differences in AML blasts and LSCs, the molecular pathways related to mitochondria and metabolism are druggable and targeted in leukemia therapies, with a distinct interest for Venetoclax, which has revolutionized the therapeutic paradigms of several leukemia subtype, unfit for intensive treatment regimens.

Diversity-oriented synthesis encoded by deoxyoligonucleotides

Diversity-oriented synthesis (DOS) is a powerful strategy to prepare molecules with underrepresented features in commercial screening collections, resulting in the elucidation of novel biological mechanisms. In parallel to the development of DOS, DNA-encoded libraries (DELs) have emerged as an effective, efficient screening strategy to identify protein binders. Despite recent advancements in this field, most DEL syntheses are limited by the presence of sensitive DNA-based constructs. Here, we describe the design, synthesis, and validation experiments performed for a 3.7 million-member DEL, generated using diverse skeleton architectures with varying exit vectors and derived from DOS, to achieve structural diversity beyond what is possible by varying appendages alone. We also show screening results for three diverse protein targets. We will make this DEL available to the academic scientific community to increase access to novel structural features and accelerate early-phase drug discovery.

The Therapeutic Potential of a Strategy to Prevent Acute Myeloid Leukemia Stem Cell Reprogramming in Older Patients

Acute myeloid leukemia (AML) is the most common and incurable leukemia subtype. Despite extensive research into the disease's intricate molecular mechanisms, effective treatments or expanded diagnostic or prognostic markers for AML have not yet been identified. The morphological, immunophenotypic, cytogenetic, biomolecular, and clinical characteristics of AML patients are extensive and complex. Leukemia stem cells (LSCs) consist of hematopoietic stem cells (HSCs) and cancer cells transformed by a complex, finely-tuned interaction that causes the complexity of AML. Microenvironmental regulation of LSCs dormancy and the diagnostic and therapeutic implications for identifying and targeting LSCs due to their significance in the pathogenesis of AML are discussed in this review. It is essential to perceive the relationship between the niche for LSCs and HSCs, which together cause the progression of AML. Notably, methylation is a well-known epigenetic change that is significant in AML, and our data also reveal that microRNAs are a unique factor for LSCs. Multiple-targeted approaches to reduce the risk of epigenetic factors, such as the administration of natural compounds for the elimination of local LSCs, may prevent potentially fatal relapses. Furthermore, the survival analysis of overlapping genes revealed that specific targets had significant effects on the survival and prognosis of patients. We predict that the multiple-targeted effects of herbal products on epigenetic modification are governed by different mechanisms in AML and could prevent potentially fatal relapses. Thus, these strategies can facilitate the incorporation of herbal medicine and natural compounds into the advanced drug discovery and development processes achievable with Network Pharmacology research.

A Study to Explore the Role of IDH1 (R132) Mutation on Imatinib Toxicity and Effect of ABCG2/OCT1 Expression on N-Desmethyl Imatinib Plasma Level in Egyptian Chronic Myeloid Leukemia Patients

Imatinib mesylate (IM) is the gold standard for treatment of Chronic Myeloid Leukemia (CML). This study aimed to gain more knowledge of the altered PK, pharmacogenetic factors, and gene expression leading to variable IM levels. Fifty patients with chronic phase-CML were enrolled in this study and divided as 25 responders and 25 non-responders (patients are directly recruited after response assessment). HPLC/MS/MS was used to determine trough and peak concentration of imatinib and N-desmethyl imatinib in the blood. PCR-RFLP technique was used to detect IDH1 gene mutation (R132). The median value of IM trough level was significantly higher, the P/T ratio was significantly lower and the α-1-acid glycoprotein (AGP) was significantly higher among responders compared to non-responders (P=0.007, 0.009 and 0.048, respectively). Higher N-desmethyl imatinib peak plasma concentration was observed with low mRNA expression of ABCG2 and OCT1 (P=0.01 and 0.037, respectively). IDH1 R132 gene mutation was associated with a significant increase in toxicities (P=0.028). In conclusion, IM trough level, P/T ratio and AGP was significantly higher in responders. In addition, ABCG2 and OCT1 gene expression may affect the interindividual PK variation. Although a prospective study with a larger patient population is necessary to validate these findings. IDH1 mutation is a predictor of increased toxicity with IM treatment.

Current and Emerging Techniques for Diagnosis and MRD Detection in AML: A Comprehensive Narrative Review

Acute myeloid leukemia (AML) comprises a group of hematologic neoplasms characterized by abnormal differentiation and proliferation of myeloid progenitor cells. AML is associated with poor outcome due to the lack of efficient therapies and early diagnostic tools. The current gold standard diagnostic tools are based on bone marrow biopsy. These biopsies, apart from being very invasive, painful, and costly, have low sensitivity. Despite the progress uncovering the molecular pathogenesis of AML, the development of novel detection strategies is still poorly explored. This is particularly important for patients that check the criteria for complete remission after treatment, since they can relapse through the persistence of some leukemic stem cells. This condition, recently named as measurable residual disease (MRD), has severe consequences for disease progression. Hence, an early and accurate diagnosis of MRD would allow an appropriate therapy to be tailored, improving a patient's prognosis. Many novel techniques with high potential in disease prevention and early detection are being explored. Among them, microfluidics has flourished in recent years due to its ability at processing complex samples as well as its demonstrated capacity to isolate rare cells from biological fluids. In parallel, surface-enhanced Raman scattering (SERS) spectroscopy has shown outstanding sensitivity and capability for multiplex quantitative detection of disease biomarkers. Together, these technologies can allow early and cost-effective disease detection as well as contribute to monitoring the efficiency of treatments. In this review, we aim to provide a comprehensive overview of AML disease, the conventional techniques currently used for its diagnosis, classification (recently updated in September 2022), and treatment selection, and we also aim to present how novel technologies can be applied to improve the detection and monitoring of MRD.

Targeted Therapy Development in Acute Myeloid Leukemia

Therapeutic developments targeting acute myeloid leukemia (AML) have been in the pipeline for five decades and have recently resulted in the approval of multiple targeted therapies. However, there remains an unmet need for molecular treatments that can deliver long-term remissions and cure for this heterogeneous disease. Previously, a wide range of small molecule drugs were developed to target sub-types of AML, mainly in the relapsed and refractory setting; however, drug resistance has derailed the long-term efficacy of these as monotherapies. Recently, the small molecule venetoclax was introduced in combination with azacitidine, which has improved the response rates and the overall survival in older adults with AML compared to those of chemotherapy. However, this regimen is still limited by cytotoxicity and is not curative. Therefore, there is high demand for therapies that target specific abnormalities in AML while sparing normal cells and eliminating leukemia-initiating cells. Despite this, the urgent need to develop these therapies has been hampered by the complexities of this heterogeneous disease, spurring the development of innovative therapies that target different mechanisms of leukemogenesis. This review comprehensively addresses the development of novel targeted therapies and the translational perspective for acute myeloid leukemia, including the development of selective and non-selective drugs.

The role of autophagy in acute myeloid leukemia development

INTRODUCTION

Autophagy is a highly conservative self-degradative process. It aims at elimination-impaired proteins and cellular organelles. Previous research confirmed the autophagy role in cancer pathogenesis.

AREAS COVERED

This article discusses the role of autophagy in the development of AML. Autophagy seems to be a 'double-sword' mechanism, hence, either its suppression or induction could promote neoplasm growth. This mechanism could also be the aim of the 'molecular targeted therapy.' Chemo- and radiotherapy induce cellular stress in neoplasm cells with subsequent autophagy suppression. Simultaneously, it is claimed that the autophagy suppression increases chemosensitivity 'in neoplastic cells. Some agents, like bortezomib, in turn could promote autophagy process, e.g. in AML (acute myeloid leukemia). However, currently there are not many studies focusing on the role of autophagy in patients suffering for AML. In this review, we summarize the research done so far on the role of autophagy in the development of AML.

EXPERT OPINION

The analysis of autophagy genes expression profiling in AML could be a relevant factor in the diagnostic process and treatment 'individualization.' Autophagy modulation seems to be a relevant target in the oncological therapy - it could limit disease progression and increase the effectiveness of treatment.

The Origin of Clonal Hematopoiesis and Its Implication in Human Diseases

Clonal expansion of hematopoietic cells is first observed in hematological malignancies where all the leukemic cells can be traced back to a single cell carrying oncogenic alterations. Interestingly, expansion of hematopoietic clones with defined genomic alterations, including single nucleotide variants (SNVs), small insertions and deletions (indels), and large structural chromosomal alterations (CAs), is also found in the healthy population. These genomic changes often affect leukemia driver genes. As a result, healthy individuals bearing such clonal hematopoiesis (CH) are at a higher risk of hematological malignancies. In addition to blood cancers, SNV/indel-related CH has been found associated with elevated cardiovascular and all-cause mortality, indicating adverse impacts of abnormalities in the blood on the normal functions of non-hematological tissues. In the past decade, much effort has been invested in understanding the origins of CH and its causal relationship with diseases in hematological and non-hematological tissues. Here, we review recent progress in these areas and discuss future directions that can be pursued to translate the acquired knowledge into better management of CH-related diseases.

The Effect of Oxidative Phosphorylation on Cancer Drug Resistance

Recent studies have shown that oxidative phosphorylation (OXPHOS) is a target for the effective attenuation of cancer drug resistance. OXPHOS inhibitors can improve treatment responses to anticancer therapy in certain cancers, such as melanomas, lymphomas, colon cancers, leukemias and pancreatic ductal adenocarcinoma (PDAC). However, the effect of OXPHOS on cancer drug resistance is complex and associated with cell types in the tumor microenvironment (TME). Cancer cells universally promote OXPHOS activity through the activation of various signaling pathways, and this activity is required for resistance to cancer therapy. Resistant cancer cells are prevalent among cancer stem cells (CSCs), for which the main metabolic phenotype is increased OXPHOS. CSCs depend on OXPHOS to survive targeting by anticancer drugs and can be selectively eradicated by OXPHOS inhibitors. In contrast to that in cancer cells, mitochondrial OXPHOS is significantly downregulated in tumor-infiltrating T cells, impairing antitumor immunity. In this review, we summarize novel research showing the effect of OXPHOS on cancer drug resistance, thereby explaining how this metabolic process plays a dual role in cancer progression. We highlight the underlying mechanisms of metabolic reprogramming in cancer cells, as it is vital for discovering new drug targets.

Glutamine metabolism and radiosensitivity: Beyond the Warburg effect

Mounting data suggest that cancer cell metabolism can be utilized therapeutically to halt cell proliferation, metastasis and disease progression. Radiation therapy is a critical component of cancer treatment in curative and palliative settings. The use of metabolism-based therapeutics has become increasingly popular in combination with radiotherapy to overcome radioresistance. Over the past year, a focus on glutamine metabolism in the setting of cancer therapy has emerged. In this mini-review, we discuss several important ways (DNA damage repair, oxidative stress, epigenetic modification and immune modulation) glutamine metabolism drives cancer growth and progression, and present data that inhibition of glutamine utilization can lead to radiosensitization in preclinical models. Future research is needed in the clinical realm to determine whether glutamine antagonism is a feasible synergistic therapy that can be combined with radiotherapy.

A tubulin binding molecule drives differentiation of acute myeloid leukemia cells

Despite much progress in developing better drugs, many patients with acute myeloid leukemia (AML) still die within a year of diagnosis. This is partly because it is difficult to identify therapeutic targets that are effective across multiple AML subtypes. One common factor across AML subtypes is the presence of a block in differentiation. Overcoming this block should allow for the identification of therapies that are not dependent on a specific mutation for their efficacy. Here, we used a phenotypic screen to identify compounds that stimulate differentiation in genetically diverse AML cell lines. Lead compounds were shown to decrease tumor burden and to increase survival in vivo. Using multiple complementary target deconvolution approaches, these compounds were revealed to be anti-mitotic tubulin disruptors that cause differentiation by inducing a G2-M mitotic arrest. Together, these results reveal a function for tubulin disruptors in causing differentiation of AML cells.

Combining empirical knowledge, in silico molecular docking and ADMET profiling to identify therapeutic phytochemicals from Brucea antidysentrica for acute myeloid leukemia

Acute myeloid leukemia (AML) is one of the deadly cancers. Chemotherapy is the first-line treatment and the only curative intervention is stem cell transplantation which are intolerable for aged and comorbid patients. Therefore, finding complementary treatment is still an active research area. For this, empirical knowledge driven search for therapeutic agents have been carried out by long and arduous wet lab processes. Nonetheless, currently there is an accumulated bioinformatics data about natural products that enabled the use of efficient and cost effective in silico methods to find drug candidates. In this work, therefore, we set out to computationally investigate the phytochemicals from Brucea antidysentrica to identify therapeutic phytochemicals for AML. We performed in silico molecular docking of compounds against AML receptors IDH2, MCL1, FLT3 and BCL2. Phytochemicals were docked to AML receptors at the same site where small molecule drugs were bound and their binding affinities were examined. In addition, random compounds from PubChem were docked with AML targets and their docking score was compared with that of phytochemicals using statistical analysis. Then, non-covalent interactions between phytochemicals and receptors were identified and visualized using discovery studio and Protein-Ligand Interaction Profiler web tool (PLIP). From the statistical analysis, most of the phytochemicals exhibited significantly lower (p-value ≤ 0.05) binding energies compared with random compounds. Using cutoff binding energy of less than or equal to one standard deviation from the mean of the phytochemicals’ binding energies for each receptor, 12 phytochemicals showed considerable binding affinity. Especially, hydnocarpin (-8.9 kcal/mol) and yadanzioside P (-9.4 kcal/mol) exhibited lower binding energy than approved drugs AMG176 (-8.6 kcal/mol) and gilteritinib (-9.1 kcal/mol) to receptors MCL1 and FLT3 respectively, indicating their potential to be lead molecules. In addition, most of the phytochemicals possessed acceptable drug-likeness and absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Based on the binding affinities as exhibited by the molecular docking studies supported by the statistical analysis, 12 phytochemicals from Brucea antidysentrica (1,11-dimethoxycanthin-6-one, 1-methoxycanthin-6-one, 2-methoxycanthin-6-one, beta-carboline-1-propionic acid, bruceanol A, bruceanol D, bruceanol F, bruceantarin, bruceantin, canthin-6-one, hydnocarpin, and yadanzioside P) can be considered as candidate compounds to prevent and manage AML. However, the phytochemicals should be further studied using in vivo & in vitro experiments on AML models. Therefore, this study concludes that combination of empirical knowledge, in silico molecular docking and ADMET profiling is useful to find natural product-based drug candidates. This technique can be applied to other natural products with known empirical efficacy.

Selective CDK9 Inhibition by Natural Compound Toyocamycin in Cancer Cells

Simple Summary

By combining drug screens, transcriptomic studies, and in vitro assays, our study identified the natural product toyocamycin as a potent and selective CDK9 inhibitor. Thus, toyocamycin can be used as a new small molecule to modulate CDK9 activity in preclinical research. Through docking simulations, we identified its specific binding sites, which could spark some interest to design novel small molecule CDK9 inhibitors.

Abstract

Aberrant transcription in cancer cells involves the silencing of tumor suppressor genes (TSGs) and activation of oncogenes. Transcriptomic changes are associated with epigenomic alterations such as DNA-hypermethylation, histone deacetylation, and chromatin condensation in promoter regions of silenced TSGs. To discover novel drugs that trigger TSG reactivation in cancer cells, we used a GFP-reporter system whose expression is silenced by promoter DNA hypermethylation and histone deacetylation. After screening a natural product drug library, we identified that toyocamycin, an adenosine-analog, induces potent GFP reactivation and loss of clonogenicity in human colon cancer cells. Connectivity-mapping analysis revealed that toyocamycin produces a pharmacological signature mimicking cyclin-dependent kinase (CDK) inhibitors. RNA-sequencing revealed that the toyocamycin transcriptomic signature resembles that of a specific CDK9 inhibitor (HH1). Specific inhibition of RNA Pol II phosphorylation level and kinase assays confirmed that toyocamycin specifically inhibits CDK9 (IC₅₀ = 79 nM) with a greater efficacy than other CDKs (IC₅₀ values between 0.67 and 15 µM). Molecular docking showed that toyocamycin efficiently binds the CDK9 catalytic site in a conformation that differs from other CDKs, explained by the binding contribution of specific amino acids within the catalytic pocket and protein backbone. Altogether, we demonstrated that toyocamycin exhibits specific CDK9 inhibition in cancer cells, highlighting its potential for cancer chemotherapy.

Digital Droplet PCR in Hematologic Malignancies: A New Useful Molecular Tool

Digital droplet PCR (ddPCR) is a recent version of quantitative PCR (QT-PCR), useful for measuring gene expression, doing clonality assays and detecting hot spot mutations. In respect of QT-PCR, ddPCR is more sensitive, does not need any reference curve and can quantify one quarter of samples already defined as "positive but not quantifiable". In the IgH and TCR clonality assessment, ddPCR recapitulates the allele-specific oligonucleotide PCR (ASO-PCR), being not adapt for detecting clonal evolution, that, on the contrary, does not represent a pitfall for the next generation sequencing (NGS) technique. Differently from NGS, ddPCR is not able to sequence the whole gene, but it is useful, cheaper, and less time-consuming when hot spot mutations are the targets, such as occurs with IDH1, IDH2, NPM1 in acute leukemias or T315I mutation in Philadelphia-positive leukemias or JAK2 in chronic myeloproliferative neoplasms. Further versions of ddPCR, that combine different primers/probes fluorescences and concentrations, allow measuring up to four targets in the same PCR reaction, sparing material, time, and money. ddPCR is also useful for quantitating BCR-ABL1 fusion gene, WT1 expression, donor chimerism, and minimal residual disease, so helping physicians to realize that "patient-tailored therapy" that is the aim of the modern hematology.

Targeting Energy Metabolism in Cancer Treatment

Cancer is the second most common cause of death worldwide after cardiovascular diseases. The development of molecular and biochemical techniques has expanded the knowledge of changes occurring in specific metabolic pathways of cancer cells. Increased aerobic glycolysis, the promotion of anaplerotic responses, and especially the dependence of cells on glutamine and fatty acid metabolism have become subjects of study. Despite many cancer treatment strategies, many patients with neoplastic diseases cannot be completely cured due to the development of resistance in cancer cells to currently used therapeutic approaches. It is now becoming a priority to develop new treatment strategies that are highly effective and have few side effects. In this review, we present the current knowledge of the enzymes involved in the different steps of glycolysis, the Krebs cycle, and the pentose phosphate pathway, and possible targeted therapies. The review also focuses on presenting the differences between cancer cells and normal cells in terms of metabolic phenotype. Knowledge of cancer cell metabolism is constantly evolving, and further research is needed to develop new strategies for anti-cancer therapies.

Biology of IDH mutant cholangiocarcinoma

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are the most frequently mutated metabolic genes across human cancers. These hotspot gain-of-function mutations cause the IDH enzyme to aberrantly generate high levels of the oncometabolite, R-2-hydroxyglutarate, which competitively inhibits enzymes that regulate epigenetics, DNA repair, metabolism, and other processes. Among epithelial malignancies, IDH mutations are particularly common in intrahepatic cholangiocarcinoma (iCCA). Importantly, pharmacological inhibition of mutant IDH (mIDH) 1 delays progression of mIDH1 iCCA, indicating a role for this oncogene in tumor maintenance. However, not all patients receive clinical benefit, and those who do typically show stable disease rather than significant tumor regressions. The elucidation of the oncogenic functions of mIDH is needed to inform strategies that can more effectively harness mIDH as a therapeutic target. This review will discuss the biology of mIDH iCCA, including roles of mIDH in blocking cell differentiation programs and suppressing antitumor immunity, and the potential relevance of these effects to mIDH1-targeted therapy. We also cover opportunities for synthetic lethal therapeutic interactions that harness the altered cell state provoked by mIDH1 rather than inhibiting the mutant enzyme. Finally, we highlight key outstanding questions in the biology of this fascinating and incompletely understood oncogene.

In vivo anti-tumor effect of PARP inhibition in IDH1/2 mutant MDS/AML resistant to targeted inhibitors of mutant IDH1/2

Treatment options for patients with relapsed/ refractory acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are scarce. Recurring mutations, such as mutations in isocitrate dehydrogenase-1 and −2 (IDH1/2) are found in subsets of AML and MDS, are therapeutically targeted by mutant enzyme-specific small molecule inhibitors (IDH^mi). IDH mutations induce diverse metabolic and epigenetic changes that drive malignant transformation. IDH^mi alone are not curative and resistance commonly develops, underscoring the importance of alternate therapeutic options. We were first to report that IDH1/2 mutations induce a homologous recombination (HR) defect which confers sensitivity to poly (ADP)-ribose polymerase inhibitors (PARPi). Here, we show that the PARPi olaparib is effective against primary patient-derived IDH1/2-mutant AML/ MDS xeno-grafts (PDXs). Olaparib efficiently reduced overall engraftment and leukemia-initiating cell frequency as evident in serial transplantation assays in IDH1/2-mutant but not -wildtype AML/MDS PDXs. Importantly, we show that olaparib is effective in both IDH^mi-naïve and -resistant AML PDXs, critical given the high relapse and refractoriness rates to IDH^mi. Our pre-clinical studies provide a strong rationale for the translation of PARP inhibition to patients with IDH1/2-mutant AML/ MDS, providing an additional line of therapy for patients who do not respond to or relapse after targeted mutant IDH inhibition.

Targetable IDH1 mutation identified in a rare case of pancreatic serous cystadenocarcinoma but not a series of serous cystadenomas

Serous cystadenocarcinoma (SCAC) of the pancreas is rare, with only 35 cases reported in the literature. We present a case of SCAC, comparing the clinical presentation, management and molecular features of this case to a series of serous cystadenoma (SCA), which may be a precursor. Compared with SCAs (n = 5), SCAC was larger (11.5 vs median 3.6 cm). The case of SCAC invaded the spleen and exhibited distant metastasis, a requirement for diagnosis since pathologic features are otherwise indistinguishable from SCA. VHL mutations have been reported in about half of SCA in the literature. Accordingly, we identified either somatic or germline VHL mutations in 3 of 5 SCAs (60%), yet no pathogenic mutation was identified in the SCAC. A somatic mutation in IDH1 was found in SCAC only. This has been associated with multiple malignancies, is targetable with the drug ivosidenib and should be studied as a progression factor in SCAC.

Emvododstat, a Potent Dihydroorotate Dehydrogenase Inhibitor, Is Effective in Preclinical Models of Acute Myeloid Leukemia

Blocking the pyrimidine nucleotide de novo synthesis pathway by inhibiting dihydroorotate dehydrogenase (DHODH) results in the cell cycle arrest and/or differentiation of rapidly proliferating cells including activated lymphocytes, cancer cells, or virally infected cells. Emvododstat (PTC299) is an orally bioavailable small molecule that inhibits DHODH. We evaluated the potential for emvododstat to inhibit the progression of acute myeloid leukemia (AML) using several in vitro and in vivo models of the disease. Broad potent activity was demonstrated against multiple AML cell lines, AML blasts cultured ex vivo from patient blood samples, and AML tumor models including patient-derived xenograft models. Emvododstat induced differentiation, cytotoxicity, or both in primary AML patient blasts cultured ex vivo with 8 of 10 samples showing sensitivity. AML cells with diverse driver mutations were sensitive, suggesting the potential of emvododstat for broad therapeutic application. AML cell lines that are not sensitive to emvododstat are likely to be more reliant on the salvage pathway than on de novo synthesis of pyrimidine nucleotides. Pharmacokinetic experiments in rhesus monkeys demonstrated that emvododstat levels rose rapidly after oral administration, peaking about 2 hours post-dosing. This was associated with an increase in the levels of dihydroorotate (DHO), the substrate for DHODH, within 2 hours of dosing indicating that DHODH inhibition is rapid. DHO levels declined as drug levels declined, consistent with the reversibility of DHODH inhibition by emvododstat. These preclinical findings provide a rationale for clinical evaluation of emvododstat in an ongoing Phase 1 study of patients with relapsed/refractory acute leukemias.

Revisiting therapeutic strategies for ovarian cancer by focusing on redox homeostasis

Recent advances in molecular genetics have expanded our understanding of ovarian cancer. High levels of reactive oxygen species (ROS) and upregulation of antioxidant genes are common characteristic features of human cancers. This review reconsiders novel therapeutic strategies for ovarian cancer by focusing on redox homeostasis. A literature search was performed for preclinical and clinical studies published between January 1998 and October 2021 in the PubMed database using a combination of specific terms. ROS serves a central role in tumor suppression and progression by inducing DNA damage and mutations, genomic instability, and aberrant anti- and pro-tumorigenic signaling. Cancer cells increase their antioxidant capacity to neutralize the extra ROS. Additionally, antioxidants, such as CD44 variant isoform 9 (CD44v9) and nuclear factor erythroid 2-related factor 2 (Nrf2), mediate redox homeostasis in ovarian cancer. Furthermore, studies conducted on different cancer types revealed the dual role of antioxidants in tumor progression and inhibition. However, in animal models, genetic loss of antioxidant capacity in the host cannot block cancer initiation and progression. Host-derived antioxidant systems are essential to suppress carcinogenesis, suggesting that antioxidants serve a pivotal role in suppressing cancer development. By contrast, antioxidant activation in cancer cells confers aggressive phenotypes. Antioxidant inhibitors can promote cancer cell death by enhancing ROS levels. Concurrent inhibition of CD44v9 and Nrf2 may trigger apoptosis induction, potentiate chemosensitivity and enhance antitumor activities through the ROS-activated p38/p21 pathway. Antioxidants may have tumor-promoting and -suppressive functions. Therefore, an improved understanding of the role of antioxidants in redox homeostasis and developing antioxidant-specific inhibitors is necessary for treating ovarian cancer.

Diagnostic performance of edited 2HG MR spectroscopy of central glioma in the clinical environment

OBJECTIVE

Oncometabolite D-2-hydroxyglutarate (2HG) is pooled in isocitrate dehydrogenase (IDH)-mutant glioma cells. Detecting 2HG by MR spectroscopy (MRS) has been proven viable in the last decade but has not entirely found its way into the clinical routine. This study aimed to explore the adoption of 2HG MRS while acknowledging factors that influence its performance in the clinical environment.

METHODS

Thirty-nine MR spectra were acquired and reported prospectively in patients with suspected glioma using a 3 T system with Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence utilizing averaged free induction decay (FID) signals. Postprocessing and evaluation of spectra were performed with jMRUI and LCModel. 2HG concentration estimates, 2HG/Cr ratio, together with quality measures, including Cramér-Rao lower bounds (CRLBs), full-width at half-maximum (FWHM) values, and signal-to-noise ratio (SNR) were calculated using LCModel. Immunohistochemistry and genomic analysis results used as a ground truth were available for 15 patients.

RESULTS

The threshold for test positivity was set according to the ROC curve at 1 mM. Calculated sensitivity was 57.14% (95% CI 0.20-0.88), specificity 87.5% (95% CI 0.46-0.99), positive predictive value 80%, and negative predictive value 70%. Overall diagnostic accuracy was 73.33% (95% CI 0.45-0.92). The 2HG/Cr ratio with the cutoff value 0.085 significantly improved sensitivity and overall diagnostic accuracy [85.71%, 95% CI 0.42-1.00 and 86.67%, (95% CI 0.60-0.98), respectively].

CONCLUSION

Multiple factors compromising spectral quality in the clinical adoption of edited 2HG MRS resulted in diminished sensitivity but clinically acceptable specificity. Furthermore, the 2HG/Cr ratio performs better than the sole 2HG concentration estimate in the pre-operative setting.

Revealing the Mysteries of Acute Myeloid Leukemia: From Quantitative PCR through Next-Generation Sequencing and Systemic Metabolomic Profiling

The efforts made in the last decade regarding the molecular landscape of acute myeloid leukemia (AML) have created the possibility of obtaining patients’ personalized treatment. Indeed, the improvement of accurate diagnosis and precise assessment of minimal residual disease (MRD) increased the number of new markers suitable for novel and targeted therapies. This progress was obtained thanks to the development of molecular techniques starting with real-time quantitative PCR (Rt-qPCR) passing through digital droplet PCR (ddPCR) and next-generation sequencing (NGS) up to the new attractive metabolomic approach. The objective of this surge in technological advances is a better delineation of AML clonal heterogeneity, monitoring patients without disease-specific mutation and designing customized post-remission strategies based on MRD assessment. In this context, metabolomics, which pertains to overall small molecules profiling, emerged as relevant access for risk stratification and targeted therapies improvement. In this review, we performed a detailed overview of the most popular modern methods used in hematological laboratories, pointing out their vital importance for MRD monitoring in order to improve overall survival, early detection of possible relapses and treatment efficacy.

The molecular mechanisms behind activation of FLT3 in acute myeloid leukemia and resistance to therapy by selective inhibitors

Acute myeloid leukemia is an aggressive cancer, which, in spite of increasingly better understanding of its genetic background remains difficult to treat. Mutations in the FLT3 gene are observed in ≈30% of the patients. Most of these mutations are internal tandem duplications (ITDs) of a sequence within the protein coding region, an activation mechanism that is almost non-existent with other genes and cancers. As patients each carry their own unique set of mutations, it is challenging to understand how ITDs activate the protein, and ascertain the risk for each individual patient. Available treatment options are limited due to development of drug resistance. Here, recent studies are reviewed that help to better understand the molecular mechanism behind activation of the FLT3 protein due to mutations. It is argued that difference in mutation sequences and especially location might be coupled to prognosis. When it comes to FLT3 inhibitors, key differences between them can be attributed to the mode of inhibition (type-1 and type-2 inhibitors), effective inhibitory coefficient in the blood plasma and off-target binding. Accounting for the position and length of insertions may in the future be used to predict prognosis and rationalise treatment. Development of new inhibitors must take into account the potential for resistance mutations. Inhibitors aimed at multiple specific targets are currently being developed. These, and as well as combination therapies will hopefully lead to longer periods during which targeted FLT3 therapy will remain effective.

Inhibition of pyrimidine biosynthesis by strobilurin derivatives induces differentiation of acute myeloid leukemia cells

All-trans retinoic acid-based differentiation therapies have succeeded in the treatment of acute promyelocytic leukemia, which is a rare subtype of acute myeloid leukemia (AML). Their clinical efficacy is negligible, however, for other subtypes of AML. Here, we showed that strobilurin derivatives, a well-established class of inhibitors of mitochondrial electron transport chain (ETC) complex III, possessed differentiation-inducing activity in AML cells. Impairment of mitochondrial ETC activity was involved in the differentiation effects of strobilurin derivatives, where reactive oxygen species generation appeared unnecessary. Conversely, strobilurin derivative-mediated differentiation was triggered by pyrimidine deficiency, which resulted from the inhibition of the mitochondrial-coupled dihydroorotate dehydrogenase enzyme. Moreover, strobilurin derivative-mediated pyrimidine depletion led to the activation of the Akt/mTOR cascade, which was required for the differentiation. Our study provided evidence that strobilurin derivatives may represent a novel class of differentiation-inducing agents for the treatment of AML.

Systematic review of epigenetic targets in acute myeloid leukemia

Acute myeloid leukemia (AML), although genetically and morphologically distinct from other B and T cell ALL subtypes, has one of the most rapidly progressing course and worse outcomes. The current diagnostic classification of AML offers best curative intent, the outcomes are not usually those that are expected at the start of therapy. This is partly attributed to the complex mechanism of leukemogenesis and resistance to chemotherapy. The underlying genetic mechanism of resistance is as complex as is the disease etiopathogenesis. Recent advances in therapy of drug resistant AML highlight the role of epigenetic targets. New FDA approved targeted therapy has also provided some evidence at improving outcomes in clinical trials. This review provides a detailed review of FDA approved targets and ongoing clinical trials for targeting CRISPER, CAR-T and other intestinal modalities for approach to epigenetictargets. However, this group of epigenetic targeted therapy needs more validation to prove its clinical efficacy. A systematic review of all published research on these targets, investigational agents and FDA approved targeted therapy summarizes this evidence. It also takes us through a brief review of mechanism of action and targets for therapy.

Can the New and Old Drugs Exert an Immunomodulatory Effect in Acute Myeloid Leukemia?

Simple Summary

The advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and of a tolerogenic microenvironment for acute myeloid leukemia (AML) fitness. We reviewed the “off-target” effects on the immune system of different drugs used in the treatment of AML to explore the advantages of this unexpected interaction.

Abstract

Acute myeloid leukemia (AML) is considered an immune-suppressive neoplasm capable of evading immune surveillance through cellular and environmental players. Increasing knowledge of the immune system (IS) status at diagnosis seems to suggest ever more attention of the crosstalk between the leukemic clone and its immunologic counterpart. During the last years, the advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and suppression for leukemia fitness. Considering all these premises, we reviewed the “off-target” effects on the IS of different drugs used in the treatment of AML, focusing on the main advantages of this interaction. The data reported support the idea that a successful therapeutic strategy should consider tailored approaches for performing leukemia eradication by both direct blasts killing and the engagement of the IS.

Isocitrate Dehydrogenase 2 Inhibitors for the Treatment of Hematologic Malignancies: Advances and Future Opportunities

Tumor cells frequently reprogram cellular metabolism from oxidative phosphorylation to glycolysis. Isocitrate dehydrogenase 2 (IDH2) has been intensively studied due to its involvement in the metabolic activity of cancer cells. Mutations in IDH2 promote neomorphic activity through the generation of oncometabolite 2-hydroxyglutarate (2-HG). The overproduced 2-HG can competitively inhibit α-KG-dependent dioxygenases to trigger cell differentiation disorders, a major cause of blood tumors. This review outlines recent progress in the identification of IDH2 inhibitors in blood cancer to provide a reference for ongoing and future clinical studies.

Mutational landscape of chronic myeloid leukemia: more than a single oncogene leukemia

The BCR-ABL1 fusion gene, which causes aberrant kinase activity and uncontrolled cell proliferation, is the hallmark of chronic myeloid leukemia (CML). The development of tyrosine kinase inhibitors (TKI) that target the BCR-ABL oncoprotein has led to dramatic improvement in CML management. However, some challenges remain to be addressed in the TKI era, including patient stratification and the selection of frontline TKIs and CML progression. Additionally, with the emerging goal of treatment-free remission (TFR) in CML management, biomarkers that predict the outcomes of stopping TKI remain to be identified. Notably, recent reports have revealed the power of genome screening in understanding the role of genome aberrations other than BCR-ABL1 in CML pathogenesis. These studies have discovered the presence of disease-phase specific mutations and linked certain mutations to inferior responses to TKI treatment and CML progression. A personalized approach that incorporates genetic data in tailoring treatment strategies has been successfully implemented in acute leukemia, and it represents a promising approach for the management of high-risk CML patients. In this article, we will review current knowledge about the mutational profile in different phases of CML as well as patterns of mutational dynamics in patients having different outcomes. We highlight the effects of somatic mutations involving certain genes (e.g. epigenetic modifiers) on the outcomes of TKI treatment. We also discuss the potential value of incorporating genetic data in treatment decisions and the routine care of CML patients as a future direction for optimizing CML management.

Novel agents and regimens for hematological malignancies: recent updates from 2020 ASH annual meeting

Antibodies and chimeric antigen receptor-engineered T cells (CAR-T) are increasingly used for cancer immunotherapy. Small molecule inhibitors targeting cellular oncoproteins and enzymes such as BCR-ABL, JAK2, Bruton tyrosine kinase, FLT3, BCL-2, IDH1, IDH2, are biomarker-driven chemotherapy-free agents approved for several major hematological malignancies. LOXO-305, asciminib, "off-the-shelf" universal CAR-T cells and BCMA-directed immunotherapeutics as well as data from clinical trials on many novel agents and regimens were updated at the 2020 American Society of Hematology (ASH) Annual Meeting. Major developments and updates for the therapy of hematological malignancies were delineated at the recent Winter Symposium and New York Oncology Forum from the Chinese American Hematologist and Oncologist Network (CAHON.org). This study summarized the latest updates on novel agents and regimens for hematological malignancies from the 2020 ASH annual meeting.

Mitochondrial metabolism as a target for acute myeloid leukemia treatment

Acute myeloid leukemias (AML) are a group of aggressive hematologic malignancies resulting from acquired genetic mutations in hematopoietic stem cells that affect patients of all ages. Despite decades of research, standard chemotherapy still remains ineffective for some AML subtypes and is often inappropriate for older patients or those with comorbidities. Recently, a number of studies have identified unique mitochondrial alterations that lead to metabolic vulnerabilities in AML cells that may present viable treatment targets. These include mtDNA, dependency on oxidative phosphorylation, mitochondrial metabolism, and pro-survival signaling, as well as reactive oxygen species generation and mitochondrial dynamics. Moreover, some mitochondria-targeting chemotherapeutics and their combinations with other compounds have been FDA-approved for AML treatment. Here, we review recent studies that illuminate the effects of drugs and synergistic drug combinations that target diverse biomolecules and metabolic pathways related to mitochondria and their promise in experimental studies, clinical trials, and existing chemotherapeutic regimens.

New Treatment Options for Older Patients with Acute Myeloid Leukemia

OPINION STATEMENT

The treatment of acute myeloid leukemia (AML) has evolved considerably over the past several years. Advances in the field have historically benefited younger patients; however, a growing understanding of the molecular basis of leukemogenesis has brought multiple targeted agents to the clinic for patients of all ages. These therapies have expanded the therapeutic landscape for elderly patients from more than best supportive care and low-intensity monotherapy. In general, we currently utilize a backbone regimen of a hypomethylating agent (HMA) or low-intensity chemotherapy with the BCL-2 inhibitor venetoclax for the majority of elderly patients with newly diagnosed AML. For patients with targetable mutations, we employ a doublet/triplet strategy of HMA + a targeted inhibitor +/- venetoclax, often in the context of a clinical trial. CPX-351 is reserved for patients with secondary or therapy-related AML. In this review, we will outline our approach to the treatment of elderly patients with AML, with particular emphasis on recently approved agents and emerging novel therapies.

Decitabine combined with low dose idarubicin and cytarabine (D-IA) followed by allo-HSCT improves acute myeloid leukemia and higher-risk myelodysplastic syndrome patient outcomes: results from a retrospective study

Treatment for acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS) ineligible for intensive chemotherapy is a major challenge for clinicians. We enrolled 154 patients ineligible for intensive chemotherapy who were prescribed D-IA regimen (decitabine 15-20 mg/m² days 1 to 3-5, followed by idarubicin 3 mg/m² for 5-7 days and cytarabine 30 mg/m² for 7-14 days). For AML and MDS patients, the overall response rate after two cycles was 66.4% and 76.6%, respectively, and the 2-year overall survival rates were 29% and 31%, respectively. Fourteen (13.1%) AML and five (10.6%) MDS patients underwent allo-HSCT after complete remission. The allo-HSCT group survival time was significantly longer than the control group (median survival time not reached in HSCT group, 13 and 18.5 months in non-HSCT AML and MDS group). We concluded that D-IA regimen was effective and well tolerated for patients with AML or higher-risk MDS ineligible for intensive chemotherapy.

Outcomes for Patients With IDH-Mutated Acute Myeloid Leukemia Undergoing Allogeneic Hematopoietic Cell Transplantation

Disease relapse after hematopoietic cell transplantation (HCT) is a major cause of treatment failure for patients with acute myeloid leukemia (AML). Maintenance therapy after HCT for patients with targetable mutations such as mutated IDH1 or IDH2 may improve outcomes, and clinical trials evaluating this strategy are ongoing. However, clinical outcomes of IDH1- and IDH2-mutated AML patients after HCT have not been well described. The primary objective of this study was to describe the clinical characteristics and post-HCT outcomes of IDH-mutated AML patients. Survival outcomes included progression-free survival (PFS), overall survival, and cumulative incidences of relapse and nonrelapse mortality. In this multicenter retrospective analysis, 112 adult patients with IDH1- or IDH2-mutated AML who underwent HCT and did not receive an IDH inhibitor as maintenance therapy after HCT were identified at Massachusetts General Hospital, Dana Farber Cancer Institute, and Ohio State University. Mutation testing was performed using next-generation sequencing panels. Patient characteristics were collected retrospectively, and their survival outcomes were analyzed. Univariate and multivariate analyses were performed. The median patient age was 64.1 years. The median follow-up was 27.5 months. Among patients, 78.5% had intermediate- or adverse-risk disease by European LeukemiaNET criteria. Fifty-eight percent of patients received intensive induction chemotherapy, 82% of patients underwent HCT during first complete remission (CR) or CR with incomplete hematologic recovery (CRi), and 34% of patients received myeloablative conditioning. Frequently detected co-mutations were DNMT3A (35.7%), NPM1 (33.1%), and FLT3-ITD (13.4%); TP53 mutations were detected in 3.6% of patients. For IDH1-mutated patients transplanted during first CR/CRi, the 1- and 2-year PFS was 75% and 58%, respectively. For IDH2-mutated patients transplanted in first CR/CRi, the 1- and 2-year PFS was 64% and 58%, respectively. The 2-year cumulative incidence of relapse was 31% and 25% for IDH1- and IDH2-mutated cohorts, respectively. Multivariable analysis suggested first CR/CRi and age ≤60 was associated with improved outcomes for IDH2-mutated patients. To date, this is the largest multicenter study of outcomes of IDH-mutated AML patients after HCT. Our analysis provides important benchmarks for analysis and interpretation of results emerging from clinical trials evaluating maintenance IDH1 and IDH2 inhibitor therapy for AML patients after HCT.

Linking Metabolic Reprogramming, Plasticity and Tumor Progression

Simple Summary

In the present review, we discuss the role of metabolic reprogramming which occurs in malignant cells. The process of metabolic reprogramming is also known as one of the “hallmarks of cancer”. Due to several reasons, including the origin of cancer, tumor microenvironment, and the tumor progression stage, metabolic reprogramming can be heterogeneous and dynamic. In this review, we provide evidence that the usage of metabolic drugs is a promising approach to treat cancer. However, because these drugs can damage not only malignant cells but also normal rapidly dividing cells, it is important to understand the exact metabolic changes which are elicited by particular drivers in concrete tissue and are specific for each stage of cancer development, including metastases. Finally, the review highlights new promising targets for the development of new metabolic drugs.

Abstract

The specific molecular features of cancer cells that distinguish them from the normal ones are denoted as “hallmarks of cancer”. One of the critical hallmarks of cancer is an altered metabolism which provides tumor cells with energy and structural resources necessary for rapid proliferation. The key feature of a cancer-reprogrammed metabolism is its plasticity, allowing cancer cells to better adapt to various conditions and to oppose different therapies. Furthermore, the alterations of metabolic pathways in malignant cells are heterogeneous and are defined by several factors including the tissue of origin, driving mutations, and microenvironment. In the present review, we discuss the key features of metabolic reprogramming and plasticity associated with different stages of tumor, from primary tumors to metastases. We also provide evidence of the successful usage of metabolic drugs in anticancer therapy. Finally, we highlight new promising targets for the development of new metabolic drugs.

IDH1 mutations induce organelle defects via dysregulated phospholipids

Infiltrating gliomas are devastating and incurable tumors. Amongst all gliomas, those harboring a mutation in isocitrate dehydrogenase 1 mutation (IDH1mut) acquire a different tumor biology and clinical manifestation from those that are IDH1WT. Understanding the unique metabolic profile reprogrammed by IDH1 mutation has the potential to identify new molecular targets for glioma therapy. Herein, we uncover increased monounsaturated fatty acids (MUFA) and their phospholipids in endoplasmic reticulum (ER), generated by IDH1 mutation, that are responsible for Golgi and ER dilation. We demonstrate a direct link between the IDH1 mutation and this organelle morphology via D-2HG-induced stearyl-CoA desaturase (SCD) overexpression, the rate-limiting enzyme in MUFA biosynthesis. Inhibition of IDH1 mutation or SCD silencing restores ER and Golgi morphology, while D-2HG and oleic acid induces morphological defects in these organelles. Moreover, addition of oleic acid, which tilts the balance towards elevated levels of MUFA, produces IDH1mut-specific cellular apoptosis. Collectively, these results suggest that IDH1mut-induced SCD overexpression can rearrange the distribution of lipids in the organelles of glioma cells, providing new insight into the link between lipid metabolism and organelle morphology in these cells, with potential and unique therapeutic implications.

A review of FDA-approved acute myeloid leukemia therapies beyond '7 + 3'

Introduction: The standard anthracycline and cytarabine-based chemotherapy for acute myeloid leukemia (AML) has changed relatively little since the 1970s and produces unsatisfactory outcomes in many patients. In the past two decades, a better understanding of the pathophysiology and heterogeneity of this disease has led to promising new therapies, resulting in a flurry of new drug approvals.Areas covered: The MEDLINE database, ClinicalTrials.gov and conference proceedings were reviewed for the most salient literature concerning FDA-approved drugs for AML beyond standard chemotherapy: gemtuzumab ozogamicin, hypomethylating agents, Fms-like tyrosine kinase 3 (FLT3) inhibitors, isocitrate dehydrogenase (IDH) inhibitors, venetoclax, liposomal cytarabine and daunorubicin (CPX-351), and hedgehog pathway inhibitors. Key evidence for their efficacy is discussed. For each drug category, indications, typical usage and responses, major toxicities, and future directions for research are highlighted.Expert opinion: The treatment paradigm for AML is rapidly evolving. Promising new drugs targeting driver mutations have improved outcomes in specific AML subgroups. In parallel, advances in low-intensity therapies have allowed patients unfit for standard induction chemotherapy to achieve meaningful disease control. Further work is ongoing to identify synergistic drug combinations as well as optimal treatment selection guided by individual patient and disease features.

Isocitrate dehydrogenase 1 from Acinetobacter baummanii (AbIDH1) enzymatic characterization and its regulation by phosphorylation

Acinetobacter baumannii encodes all enzymes required in the tricarboxylic acid (TCA) cycle and glyoxylate bypass except for isocitrate dehydrogenase kinase/phosphatase (IDHKP), which can phosphorylate isocitrate dehydrogenase (IDH) at a substrate-binding Ser site and control the carbon flux in enterobacteria, such as Escherichia coli. The potential kinase was not successfully pulled down from A. baumannii cell lyase; therefore, whether the IDH 1 from A. baumannii (AbIDH1) can be phosphorylated to regulate intracellular carbon flux has not been clarified. Herein, the AbIDH1 gene was cloned, the encoded protein was expressed and purified to homogeneity, and phosphorylation and enzyme kinetics were evaluated in vitro. Gel filtration and SDS-PAGE analyses showed that AbIDH1 is an 83.5 kDa homodimer in solution. The kinetics showed that AbIDH1 is a fully active NADP-dependent enzyme. The Michaelis constant K_m is 46.6 (Mn²⁺) and 18.1 μM (Mg²⁺) for NADP⁺ and 50.5 (Mn²⁺) and 65.4 μM (Mg²⁺) for the substrate isocitrate. Phosphorylation experiments in vitro indicated that AbIDH1 is a substrate for E. coli IDHKP. The activity of AbIDH1 treated with E. coli IDHKP immediately decreased by 80% within 9 min. Mass spectrometry indicated that the conserved Ser113 of AbIDH1 is phosphorylated. Continuous phosphorylation-mimicking mutants (Ser113Glu and Ser113Asp) lack almost all enzymatic activity. Side-chain mutations at Ser113 (Ser113Thr, Ser113Ala, Ser113Gly and Ser113Tyr) remarkably reduce the enzymatic activity. Understanding the potential of AbIDH1 phosphorylation enables further investigations of the AbIDH1 physiological functions in A. baumannii.

Advances in Epigenetic Cancer Therapeutics

Cancer has traditionally been hailed a genetic disease, dictated by successive genetic aberrations which alter gene expression. Yet, recent advances in molecular sequencing technologies, enabling the characterisation of cancer patient phenotypes on a large scale, have highlighted epigenetic changes as a hallmark of cancer. Epigenetic modifications, including DNA methylation and demethylation and histone modifications, have been found to play a key role in the pathogenesis of a wide variety of cancers through the regulation of chromatin state, gene expression and other nuclear events. Targeting epigenetic aberrations offers remarkable promise as a potential anti-cancer therapy given the reversible nature of epigenetic changes. Hence, epigenetic therapy has emerged as a rapidly advancing field of cancer research. A plethora of epigenetic therapies which inhibit enzymes of post-translational histone modifications, so-called 'writers', 'erasers' and 'readers', have been developed, with several epigenetic inhibitor agents approved for use in routine clinical practice. Epigenetic therapeutics inhibit the methylation or demethylation and acetylation or deacetylation of DNA and histone proteins. Their targets include writers (DNA methyltransferases [DNMT], histone acetyltransferases [HAT] and histone deacetylases [HDAC]) and erasers (histone demethylases [HDM] and histone methylases [HMT]). With new epigenetic mechanisms increasingly being elucidated, a vast array of targets and therapeutics have been brought to the fore. This review discusses recent advances in cancer epigenetics with a focus on molecular targets and mechanisms of action of epigenetic cancer therapeutics.

Current and emerging molecular and epigenetic disease entities in acute myeloid leukemia and a critical assessment of their therapeutic modalities

Acute myeloid leukemia (AML) is the most frequently diagnosed acute leukemia, and its incidence increases with age. Although the etiology of AML remains unknown, exposure to genotoxic agents or some prior hematologic disorders could lead to the development of this condition. The pathogenesis of AML involves the development of malignant transformation of hematopoietic stem cells that undergo successive genomic alterations, ultimately giving rise to a full-blown disease. From the disease biology perspective, AML is considered to be extremely complex with significant genetic, epigenetic, and phenotypic variations. Molecular and cytogenetic alterations in AML include mutations in those subsets of genes that are involved in normal cell proliferation, maturation and survival, thus posing significant challenge to targeting these pathways without attendant toxicity. In addition, multiple malignant cells co-exist in the majority of AML patients. Individual subclones are characterized by unique genetic and epigenetic abnormalities, which contribute to the differences in their response to treatment. As a result, despite a dramatic progress in our understanding of the pathobiology of AML, not much has changed in therapeutic approaches to treat AML in the past four decades. Dose and regimen modifications with improved supportive care have contributed to improved outcomes by reducing toxicity-related side effects. Several drug candidates are currently being developed, including targeted small-molecule inhibitors, cytotoxic chemotherapies, monoclonal antibodies and epigenetic drugs. This review summarizes the current state of affairs in the pathobiological and therapeutic aspects of AML.

Therapeutic targeting of FLT3 and associated drug resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease caused by several gene mutations and cytogenetic abnormalities affecting differentiation and proliferation of myeloid lineage cells. FLT3 is a receptor tyrosine kinase commonly overexpressed or mutated, and its mutations are associated with poor prognosis in AML. Although aggressive chemotherapy often followed by hematopoietic stem cell transplant is the current standard of care, the recent approval of FLT3-targeted drugs is revolutionizing AML treatment that had remained unchanged since the 1970s. However, despite the dramatic clinical response to targeted agents, such as FLT3 inhibitors, remission is almost invariably short-lived and ensued by relapse and drug resistance. Hence, there is an urgent need to understand the molecular mechanisms driving drug resistance in order to prevent relapse. In this review, we discuss FLT3 as a target and highlight current understanding of FLT3 inhibitor resistance.