The emerging role of d-2-hydroxyglutarate as an oncometabolite in hematolymphoid and central nervous system neoplasms

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.

Targeting Oncometabolites in Peritoneal Cancers: Preclinical Insights and Therapeutic Strategies

Peritoneal cancers present significant clinical challenges with poor prognosis. Understanding the role of cancer cell metabolism and cancer-promoting metabolites in peritoneal cancers can provide new insights into the mechanisms that drive tumor progression and can identify novel therapeutic targets and biomarkers for early detection, prognosis, and treatment response. Cancer cells dynamically reprogram their metabolism to facilitate tumor growth and overcome metabolic stress, with cancer-promoting metabolites such as kynurenines, lactate, and sphingosine-1-phosphate promoting cell proliferation, angiogenesis, and immune evasion. Targeting cancer-promoting metabolites could also lead to the development of effective combinatorial and adjuvant therapies involving metabolic inhibitors for the treatment of peritoneal cancers. With the observed metabolomic heterogeneity in cancer patients, defining peritoneal cancer metabolome and cancer-promoting metabolites holds great promise for improving outcomes for patients with peritoneal tumors and advancing the field of precision cancer medicine. This review provides an overview of the metabolic signatures of peritoneal cancer cells, explores the role of cancer-promoting metabolites as potential therapeutic targets, and discusses the implications for advancing precision cancer medicine in peritoneal cancers.

Olutasidenib (FT-2102) in patients with relapsed or refractory IDH1-mutant glioma: A multicenter, open-label, phase Ib/II trial

BACKGROUND

Olutasidenib (FT-2102) is a highly potent, orally bioavailable, brain-penetrant and selective inhibitor of mutant isocitrate dehydrogenase 1 (IDH1). The aim of the study was to determine the safety and clinical activity of olutasidenib in patients with relapsed/refractory gliomas harboring an IDH1R132X mutation.

METHODS

This was an open-label, multicenter, nonrandomized, phase Ib/II clinical trial. Eligible patients (≥18 years) had histologically confirmed IDH1R132X-mutated glioma that relapsed or progressed on or following standard therapy and had measurable disease. Patients received olutasidenib, 150 mg orally twice daily (BID) in continuous 28-day cycles. The primary endpoints were dose-limiting toxicities (DLTs) (cycle 1) and safety in phase I and objective response rate using the Modified Response Assessment in Neuro-Oncology criteria in phase II.

RESULTS

Twenty-six patients were enrolled and followed for a median 15.1 months (7.3‒19.4). No DLTs were observed in the single-agent glioma cohort and the pharmacokinetic relationship supported olutasidenib 150 mg BID as the recommended phase II dose. In the response-evaluable population, disease control rate (objective response plus stable disease) was 48%. Two (8%) patients demonstrated a best response of partial response and eight (32%) had stable disease for at least 4 months. Grade 3‒4 adverse events (≥10%) included alanine aminotransferase increased and aspartate aminotransferase increased (three [12%], each).

CONCLUSIONS

Olutasidenib 150 mg BID was well tolerated in patients with relapsed/refractory gliomas harboring an IDH1R132X mutation and demonstrated preliminary evidence of clinical activity in this heavily pretreated population.

Implications of Concurrent IDH1 and IDH2 Mutations on Survival in Glioma-A Case Report and Systematic Review

Both IDH1 (isocitrate dehydrogenase 1) and IDH2 (isocitrate dehydrogenase 2) mutations play a vital role in the development of gliomas through disruption of normal cellular metabolic processes. Here we describe a case of a patient with an IDH-mutant astrocytoma, in which both IDH1 and IDH2 mutations were detected within the same tumour. The patient remains disease-free, nine and a half years after her initial diagnosis. Interrogation of cancer genomic databases and a systematic review was undertaken, demonstrating the rarity of the co-occurrence of IDH1 and IDH2 mutations in a variety of cancer types, and in glioma specifically. Due to the favourable outcome observed in this patient, the potential effect of concurrent IDH1 and IDH2 mutations on survival was also investigated.

Targeting the Sphingolipid Rheostat in Gliomas

Gliomas are highly aggressive cancer types that are in urgent need of novel drugs and targeted therapies. Treatment protocols have not improved in over a decade, and glioma patient survival remains among the worst of all cancer types. As a result, cancer metabolism research has served as an innovative approach to identifying novel glioma targets and improving our understanding of brain tumors. Recent research has uncovered a unique metabolic vulnerability in the sphingolipid pathways of gliomas that possess the IDH1 mutation. Sphingolipids are a family of lipid signaling molecules that play a variety of second messenger functions in cellular regulation. The two primary metabolites, sphingosine-1-phosphate (S1P) and ceramide, maintain a rheostat balance and play opposing roles in cell survival and proliferation. Altering the rheostat such that the pro-apoptotic signaling of the ceramides outweighs the pro-survival S1P signaling in glioma cells diminishes the hallmarks of cancer and enhances tumor cell death. Throughout this review, we discuss the sphingolipid pathway and identify the enzymes that can be most effectively targeted to alter the sphingolipid rheostat and enhance apoptosis in gliomas. We discuss each pathway’s steps based on their site of occurrence in the organelles and postulate novel targets that can effectively exploit this vulnerability.

2-Hydroxyglutarate in Acute Myeloid Leukemia: A Journey from Pathogenesis to Therapies

The oncometabolite 2-hydroxyglutarate (2-HG) plays a key role in differentiation blockade and metabolic reprogramming of cancer cells. Approximatively 20–30% of acute myeloid leukemia (AML) cases carry mutations in the isocitrate dehydrogenase (IDH) enzymes, leading to a reduction in the Krebs cycle intermediate α-ketoglutarate (α-KG) to 2-HG. Relapse and chemoresistance of AML blasts following initial good response to standard therapy account for the very poor outcome of this pathology, which represents a great challenge for hematologists. The decrease of 2-HG levels through pharmacological inhibition of mutated IDH enzymes induces the differentiation of AML blasts and sensitizes leukemic cells to several anticancer drugs. In this review, we provide an overview of the main genetic mutations in AML, with a focus on IDH mutants and the role of 2-HG in AML pathogenesis. Moreover, we discuss the impact of high levels of 2-HG on the response of AML cells to antileukemic therapies and recent evidence for highly efficient combinations of mutant IDH inhibitors with other drugs for the management of relapsed/refractory (R/R) AML.

Changing Landscape of Systemic Therapy in Biliary Tract Cancer

Biliary tract cancers (BTC) are often diagnosed at advanced stages and have a grave outcome due to limited systemic options. Gemcitabine and cisplatin combination (GC) has been the first-line standard for more than a decade. Second-line chemotherapy (CT) options are limited. Targeted therapy or TT (fibroblast growth factor 2 inhibitors or FGFR2, isocitrate dehydrogenase 1 or IDH-1, and neurotrophic tyrosine receptor kinase or NTRK gene fusions inhibitors) have had reasonable success, but <5% of total BTC patients are eligible for them. The use of immune checkpoint inhibitors (ICI) such as pembrolizumab is restricted to microsatellite instability high (MSI-H) patients in the first line. The success of the TOPAZ-1 trial (GC plus durvalumab) is promising, with numerous trials underway that might soon bring targeted therapy (pemigatinib and infrigatinib) and ICI combinations (with CT or TT in microsatellite stable cancers) in the first line. Newer targets and newer agents for established targets are being investigated, and this may change the BTC management landscape in the coming years from traditional CT to individualized therapy (TT) or ICI-centered combinations. The latter group may occupy major space in BTC management due to the paucity of targetable mutations and a greater toxicity profile.

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.

Meta-analysis of whole-genome gene expression datasets assessing the effects of IDH1 and IDH2 mutations in isogenic disease models

Mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 are oncogenic drivers to a variable extent in several tumors, including gliomas, acute myeloid leukemia (AML), cholangiocarcinoma, melanoma, and thyroid carcinoma. The pathobiological effects of these mutations vary considerably, impeding the identification of common expression profiles. We performed an expression meta-analysis between IDH-mutant (IDH^mut) and IDH-wild-type (IDH^wt) conditions in six human and mouse isogenic disease models. The datasets included colon cancer cells, glioma cells, heart tissue, hepatoblasts, and neural stem cells. Among differentially expressed genes (DEGs), serine protease 23 (PRSS23) was upregulated in four datasets, i.e., in human colon carcinoma cells, mouse heart tissue, mouse neural stem cells, and human glioma cells. Carbonic anhydrase 2 (CA2) and prolyl 3-hydroxylase 2 (P3H2) were upregulated in three datasets, and SOX2 overlapping transcript (SOX2-OT) was downregulated in three datasets. The most significantly overrepresented protein class was termed intercellular signal molecules. An additional DEG set contained genes that were both up- and downregulated in different datasets and included oxidases and extracellular matrix structural proteins as the most significantly overrepresented protein classes. In conclusion, this meta-analysis provides a comprehensive overview of the expression effects of IDH mutations shared between different isogenic disease models. The generated dataset includes biomarkers, e.g., PRSS23 that may gain relevance for further research or clinical applications in IDH^mut tumors.

Molecular and genomic landscapes in secondary & therapy related acute myeloid leukemia

Acute myeloid leukemia (AML) is a complex, aggressive myeloid neoplasm characterized by frequent somatic mutations that influence different functional categories' genes, resulting in maturational arrest and clonal expansion. AML can arise de novo (dn-AML) or can be secondary AML (s-AML) refers to a leukemic process which may arise from an antecedent hematologic disorder (AHD-AML), mostly from a myelodysplastic syndrome (MDS) or myeloproliferative neoplasm (MPN) or can be the result of an antecedent cytotoxic chemotherapy or radiation therapy (therapy-related AML, t-AML). Clinical and biological features in secondary and therapy-related AML are distinct from de novo AML. Secondary and therapy-related AML occurs mainly in the elderly population and responds worse to therapy with higher relapse rates due to resistance to cytotoxic chemotherapy. Over the last decade, advances in molecular genetics have disclosed the sub-clonal architecture of secondary and therapy-related AML. Recent investigations have revealed that cytogenetic abnormalities and underlying genetic aberrations (mutations) are likely to be significant factors dictating prognosis and critical impacts on treatment outcome. Secondary and therapy-related AML have a poorer outcome with adverse cytogenetic abnormalities and higher recurrences of unfavorable mutations compared to de novo AML. In this review, we present an overview of the clinical features of secondary and therapy-related AML and address the function of genetic mutations implicated in the pathogenesis of secondary leukemia. Detailed knowledge of the pathogenetic mechanisms gives an overview of new prognostic markers, including targetable mutations that will presumably lead to the designing and developing novel molecular targeted therapies for secondary and therapy-related AML. Despite significant advances in knowing the genetic aspect of secondary and therapy-related AML, its influence on the disease's pathophysiology, standard treatment prospects have not significantly evolved during the past three decades. Thus, we conclude this review by summarizing the modern and developing treatment strategies in secondary and therapy-related acute myeloid leukemia.

The Combined Treatment With the FLT3-Inhibitor AC220 and the Complex I Inhibitor IACS-010759 Synergistically Depletes Wt- and FLT3-Mutated Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with a high mortality rate and relapse risk. Although progress on the genetic and molecular understanding of this disease has been made, the standard of care has changed minimally for the past 40 years and the five-year survival rate remains poor, warranting new treatment strategies. Here, we applied a two-step screening platform consisting of a primary cell viability screening and a secondary metabolomics-based phenotypic screening to find synergistic drug combinations to treat AML. A novel synergy between the oxidative phosphorylation inhibitor IACS-010759 and the FMS-like tyrosine kinase 3 (FLT3) inhibitor AC220 (quizartinib) was discovered in AML and then validated by ATP bioluminescence and apoptosis assays. In-depth stable isotope tracer metabolic flux analysis revealed that IACS-010759 and AC220 synergistically reduced glucose and glutamine enrichment in glycolysis and the TCA cycle, leading to impaired energy production and de novo nucleotide biosynthesis. In summary, we identified a novel drug combination, AC220 and IACS-010759, which synergistically inhibits cell growth in AML cells due to a major disruption of cell metabolism, regardless of FLT3 mutation status.

Targeted Therapeutic Approach Based on Understanding of Aberrant Molecular Pathways Leading to Leukemic Proliferation in Patients with Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogenous hematopoietic neoplasm with various genetic abnormalities in myeloid stem cells leading to differentiation arrest and accumulation of leukemic cells in bone marrow (BM). The multiple genetic alterations identified in leukemic cells at diagnosis are the mainstay of World Health Organization classification for AML and have important prognostic implications. Recently, understanding of heterogeneous and complicated molecular abnormalities of the disease could lead to the development of novel targeted therapeutic agents. In the past years, gemtuzumab ozogamicin, BCL-2 inhibitors (venetovlax), IDH 1/2 inhibitors (ivosidenib and enasidenib) FLT3 inhibitors (midostaurin, gilteritinib, and enasidenib), and hedgehog signaling pathway inhibitors (gladegib) have received US Food and Drug Administration (FDA) approval for the treatment of AML. Especially, AML patients with elderly age and/or significant comorbidities are not currently suitable for intensive chemotherapy. Thus, novel therapeutic planning including the abovementioned target therapies could lead to improve clinical outcomes in the patients. In the review, we will present various important and frequent molecular abnormalities of AML and introduce the targeted agents of AML that received FDA approval based on the previous studies.

Dual-Knockout of Mutant Isocitrate Dehydrogenase 1 and 2 Subtypes Towards Glioma Therapy: Structural Mechanistic Insights on the Role of Vorasidenib

Recently, Vorasidenib (AG-881) has been reported as a therapeutic alternative that exerts potent dual inhibitory activity against mIDH1/2 towards the treatment of low-grade glioma. However, structural and dynamic events associated with its dual inhibition mechanism remain unclear. As such, we employ integrative computer-assisted atomistic techniques to provide thorough structural and dynamic insights. Our analysis proved that the dual-targeting ability of AG-881 is mediated by Val255/Val294 within the binding pockets of both mIDH1 and mIDH2 which are shown to elicit a strong intermolecular interaction, thus favoring binding affinity. The structural orientations of AG-881 within the respective hydrophobic pockets allowed favorable interactions with binding site residues which accounted for its high binding free energy of -28.69 kcal/mol and -19.89 kcal/mol towards mIDH1 and mIDH2, respectively. Interestingly, upon binding, AG-881 was found to trigger systemic alterations of mIDH1 and mIDH2 characterized by restricted residue flexibility and a reduction in exposure of residues to the solvent surface area. As a result of these structural alterations, crucial interactions of the mutant enzymes were inhibited, a phenomenon that results in a suppression of the production of oncogenic stimulator 2-HG. Findings therefore provide thorough structural and dynamic insights associated with the dual inhibitory activity of AG-881 towards glioma therapy.

Hematopoietic Stem Cell Metabolism during Development and Aging

Cellular metabolism in hematopoietic stem cells (HSCs) is an area of intense research interest, but the metabolic requirements of HSCs and their adaptations to their niches during development have remained largely unaddressed. Distinctive from other tissue stem cells, HSCs transition through multiple hematopoietic sites during development. This transition requires drastic metabolic shifts, insinuating the capacity of HSCs to meet the physiological demand of hematopoiesis. In this review, we highlight how mitochondrial metabolism determines HSC fate, and especially focus on the links between mitochondria, endoplasmic reticulum (ER), and lysosomes in HSC metabolism.

Quantitative Analysis of Oncometabolite 2-Hydroxyglutarate

Gain-of-function mutations of isocitrate dehydrogenase 1 and 2 (IDH1/2) were demonstrated to induce the production and accumulation of oncometabolite 2-hydroxyglutarate (2HG). 2HG is a potent competitor of α-ketoglutarate (α-KG) and can inhibit multiple α-KG-dependent dioxygenases that are critical for regulating the metabolic and epigenetic state of cells. The accumulation of 2HG contributes to elevated risk of malignant tumors. 2HG carries an asymmetric carbon atom in its carbon backbone and therefore occurs in two enantiomers, D-2-hydroxyglutarate (D-2HG) and L-2-hydroxyglutarate (L-2HG). Each enantiomer is produced and metabolized in independent biochemical pathway and catalyzed by different enzymes. The accurate diagnosis of 2HG-related diseases relies on determining the configuration of the two enantiomers. Quantitative methods for analysis of D-2HG and L-2HG have been well developed. These analytical strategies mainly include the use of chiral chromatography medium to facilitate chromatographic separation of enantiomers prior to spectroscopy or mass spectrometry analysis and the use of chiral derivatization reagents to convert the enantiomers to diastereomers with differential physical and chemical properties that can improve their chromatographic separation. Here, we summarize and discuss these established methods for analysis of total 2HG as well as the determination of the enantiomers of D-2HG and L-2HG.

The Heterogeneity of Breast Cancer Metabolism

Despite advances in screening, therapy, and surveillance that have improved patient survival rates, breast cancer is still the most commonly diagnosed cancer and the second leading cause of cancer mortality among women [1]. Breast cancer is a highly heterogeneous disease rooted in a genetic basis, influenced by extrinsic stimuli, and reflected in clinical behavior. The diversity of breast cancer hormone receptor status and the expression of surface molecules have guided therapy decisions for decades; however, subtype-specific treatment often yields diverse responses due to varying tumor evolution and malignant potential. Although the mechanisms behind breast cancer heterogeneity is not well understood, available evidence suggests that studying breast cancer metabolism has the potential to provide valuable insights into the causes of these variations as well as viable targets for intervention.

Landscape of Tumor Suppressor Mutations in Acute Myeloid Leukemia

Acute myeloid leukemia is mainly characterized by a complex and dynamic genomic instability. Next-generation sequencing has significantly improved the ability of diagnostic research to molecularly characterize and stratify patients. This detailed outcome allowed the discovery of new therapeutic targets and predictive biomarkers, which led to develop novel compounds (e.g., IDH 1 and 2 inhibitors), nowadays commonly used for the treatment of adult relapsed or refractory AML. In this review we summarize the most relevant mutations affecting tumor suppressor genes that contribute to the onset and progression of AML pathology. Epigenetic modifications (TET2, IDH1 and IDH2, DNMT3A, ASXL1, WT1, EZH2), DNA repair dysregulation (TP53, NPM1), cell cycle inhibition and deficiency in differentiation (NPM1, CEBPA, TP53 and GATA2) as a consequence of somatic mutations come out as key elements in acute myeloid leukemia and may contribute to relapse and resistance to therapies. Moreover, spliceosomal machinery mutations identified in the last years, even if in a small cohort of acute myeloid leukemia patients, suggested a new opportunity to exploit therapeutically. Targeting these cellular markers will be the main challenge in the near future in an attempt to eradicate leukemia stem cells.

Isocitrate dehydrogenase inhibitors in acute myeloid leukemia

Isocitrate dehydrogenase (IDH) is a key enzyme involved in the conversion of isocitrate to α-ketoglutarate (α-KG) in the tricarboxylic acid (TCA) cycle. IDH mutation produces a neomorphic enzyme, which can lead to the abnormal accumulation of R-2-HG and promotes leukemogenesis. IDH mutation occurs in 20% of acute myeloid leukemia (AML) patients, mainly including IDH1 R132, IDH2 R140, and IDH2 R172. Different mutant isoforms have different prognostic values. In recent years, IDH inhibitors have shown good clinical response in AML patients. Hence, enasidenib and ivosidenib, the IDH2 and IDH1 inhibitors developed by Agios Pharmaceuticals, have been approved by the Food and Drug Administration on 1 August 2017 and 20 July 2018 for the treatment of adult relapsed or refractory (R/R) AML with IDH2 and IDH1 mutations, respectively. IDH inhibitor monotherapy for R/R AML is efficacious and safe; however, there are problems, such as primary or acquired resistance. Clinical trials of IDH inhibitors combined with hypomethylating agents or standard chemotherapy for the treatment of R/R AML or newly diagnosed AML, as well as in post hematopoietic stem cell transplantation as maintenance therapy, are ongoing. This article summarizes the use of IDH inhibitors in AML with IDH mutations.

Identification of IDH-mutant gliomas by a prognostic signature according to gene expression profiling

BACKGROUND

Isocitrate dehydrogenase (IDH) mutations are the most common genetic aberrations in gliomagenesis. We aimed to build a high-efficiency prediction gene signature in patients with IDH-mutant glioma.

METHODS

In total, 167 gliomas from Chinese Glioma Genome Atlas (CGGA) dataset were included for discovery. The Cancer Genome Atlas (TCGA) dataset was used for validation. R language was the main software environment for our statistical operation and graphics.

RESULTS

We applied the Time-Dependent ROC Curve (timeROC) method to estimate the gene prediction accuracy of 3 years and 5 years in two datasets. Seven genes were selected for further analysis (AUC ≥ 0.7 in two datasets). A seven-gene enrichment score was established to predict the overall survival of 3 years and 5 years for IDH- mutant glioma patients. Moreover, the seven-gene signature was an independent prognostic indicator for patients with IDH-mutant glioma. Gene Ontology (GO) Analysis of associated genes revealed signature-related biological process of cell cycle and division.

CONCLUSION

We have identified a seven-gene signature that can provide a more accurate predictor of 3 years and 5 years for patients with IDH-mutant glioma. Moreover, the signature may potentially help neurosurgeons with the clinical personalized management of gliomas.

Targeting IDH1 and IDH2 Mutations in Acute Myeloid Leukemia

PURPOSE OF REVIEW

Over the past decade, the pathogenic role of mutations in isocitrate dehydrogenases (IDH) 1 and 2, affecting approximately 20% of patients with AML, has been defined, allowing for the development of specific therapeutic strategies for IDH-mutant AML. In this review, the landscape and progress of targeted therapeutics aimed at IDH mutations in AML and related myeloid malignancies will be described.

RECENT FINDINGS

Since 2013, several mutant IDH-targeted inhibitors have been developed, and nearly a dozen clinical trials have opened specifically for IDH-mutant hematologic malignancies. Preliminary results for several of these investigations have shown evidence of safety, tolerability, and encouraging evidence of efficacy. Targeting IDH mutations in AML is a biologically informed and rational strategy to promote clinical responses, primarily through differentiation and maturation of the malignant clone. The use of IDH targeted therapy is expected to soon become part of a genomically defined and individualized AML treatment strategy.

Metabolic strategies of melanoma cells: Mechanisms, interactions with the tumor microenvironment, and therapeutic implications

Melanomas are metabolically heterogeneous, and they are able to adapt in order to utilize a variety of fuels that facilitate tumor progression and metastasis. The significance of metabolism in melanoma is supported by growing evidence of impact on the efficacy of contemporary therapies for this disease. There are also data to support that the metabolic phenotypes of melanoma cells depend upon contributions from both intrinsic oncogenic pathways and extrinsic factors in the tumor microenvironment. This review summarizes current understanding of the metabolic processes that promote cutaneous melanoma tumorigenesis and progression, the regulation of cancer cell metabolism by the tumor microenvironment, and the impact of metabolic pathways on targeted and immune therapies.

Breast Cancer Metabolism

Despite advances in screening, therapy, and surveillance that have improved survival rates, breast cancer is still the most commonly diagnosed cancer and the second leading cause of cancer mortality among women [1]. Breast cancer is a highly heterogeneous disease rooted in a genetic basis and reflected in clinical behavior. The diversity of breast cancer hormone receptor status and the expression of surface molecules has guided therapy decisions for decades; however, subtype-specific treatment often yields diverse responses due to varying tumor evolution and malignant potential. Although understanding the mechanisms behind breast cancer heterogeneity is still a challenge, available evidence suggests that studying its metabolism has the potential to give valuable insight into the causes of these variations, as well as viable targets for intervention.

IDH mutations associated impact on related cancer epidemiology and subsequent effect toward HIF-1α

Particular mutations in the isocitrate dehydrogenase gene (IDH) were discovered in several gliomas citing astrocytoma, oligodendroglioma, and glioblastoma multiform, but also in leukemia; these mutations were discovered in nearly all cases of secondary glioblastomas, they evolve from lower-grade gliomas, but are limited in primary high-grade glioblastoma multiform. These mutations distinctively produce (D)-2-hydroxyglutarate (D-2-HG) from alpha-ketoglutarate (α-KG). (D)-2-hydroxyglutarate is accumulated to very high concentrations which inhibit the function of enzymes that are dependent on alpha-ketoglutarate. This modification leads to a hyper-methylated state of DNA and histones, resulting in different gene expression that can activate oncogenes and inactivate tumor-suppressor genes. In our work we review the impact of the mutations that occur in IDH genes, we focus on their impact on distribution in cancer. As IDH mutations appear in many different conditions we expose the extent of IDH mutations and derivate their impact on cancer prognosis, diagnosis, and even their oncogenicity, we will also link their impact to HIF-1α and derivate some target and finally, we present some of the therapeutics under research and out on market.

Measurement of Oncometabolites D-2-Hydroxyglutaric Acid and L-2-Hydroxyglutaric Acid

We describe a liquid chromatography-tandem mass spectrometry assay for measurement of D-2-hydroxyglutaric acid and L-2-hydroxyglutaric acid. These metabolites are increased in specific inborn errors of metabolism and are now recognized as oncometabolites. The measurement of D-2-hydroxyglutarate in peripheral blood may be used as a biomarker for screening and follow-up of patients with IDH-mutated acute myeloid leukemia.

Impending Impact of Molecular Pathology on Classifying Adult Diffuse Gliomas

BACKGROUND

Progress in molecular oncology during the last decade has enabled investigators to more precisely define and group gliomas. The impacts of isocitrate dehydrogenase (IDH) mutation (mut) status and other molecular markers on the classification, prognostication, and management of diffuse gliomas are likely to be far-reaching.

METHODS

Clinical experience and the medical literature were used to assess the current status of glioma categorization and the likely impact of the pending revision of the classification scheme of the World Health Organization (WHO).

RESULTS

IDH-mut is a defining event in most adult fibrillary astrocytomas (FAs) and nearly all oligodendrogliomas (ODs). The IDH-mut status of most gliomas can be established by immunohistochemistry for the most common mutant of IDH1 (R132H). IDH wild-type (wt) diffuse gliomas include several familiar entities -- in particular, glioblastoma (GBM) and most pediatric gliomas -- as well as an assortment of less well-defined entities. The codeletion of 1p/19q distinguishes OD from FA, which, by contrast, shows frequent loss of the α thalassemia/mental retardation syndrome X-linked protein. Mixed oligoastrocytomas are typically classifiable as either OD or FA using molecular testing.

CONCLUSIONS

The current practice of designating IDH-mut WHO grade 4 astrocytoma as secondary GBM will likely be discouraged, and primary or de novo GBM, which is always IDH-wt, may lose this qualification. Histologically, low- or intermediate-grade IDH-wt gliomas with molecular changes characteristic of GBM might justify the designation of GBM WHO grade 3. Mixed oligoastrocytoma is losing popularity as a diagnostic term because most cases will fall into either the FA or OD category. Distinguishing IDH-mut from IDH-wt tumors in clinical trials is likely to clarify sensitivity rates or tumor resistance among subgroups, thus suggesting opportunities for targeted therapy.

Changes in urinary metabolic profiles of colorectal cancer patients enrolled in a prospective cohort study (ColoCare)

INTRODUCTION

Metabolomics is a valuable tool for biomarker screening of colorectal cancer (CRC). In this study, we profiled the urinary metabolomes of patients enrolled in a prospective patient cohort (ColoCare). We aimed to describe changes in the metabolome in the longer clinical follow-up and describe initial predictors as candidate markers with possibly prognostic significance.

METHODS

In total, 199 urine samples from CRC patients pre-surgery (n=97), 1-8 days post-surgery (n=12) and then after 6 and 12 months (n=52 and 38, respectively) were analyzed using both GC-MS and ¹H-NMR. Both datasets were analyzed separately with built in uni- and multivariate analyses of Metaboanalyst 2.0. Furthermore, adjusted linear mixed effects regression models were constructed.

RESULTS

Many concentrations of the metabolites derived from the gut microbiome were affected by CRC surgery, presumably indicating a tumor-induced shift in bacterial species. Associations of the microbial metabolites with disease stage indicate an important role of the gut microbiome in CRC.We were able to differentiate the metabolite profiles of CRC patients prior to surgery from those at any post-surgery timepoint using a multivariate model containing 20 marker metabolites (AUCROC=0.89; 95% CI:0.84-0.95).

CONCLUSION

To the best of our knowledge, this is one of the first metabolomic studies to follow CRC patients in a prospective setting with repeated urine sampling over time. We were able to confirm markers initially identified in case-control studies and pin point metabolites which may serve as candidates for prognostic biomarkers of CRC.

Metabolic dysregulation in monogenic disorders and cancer - finding method in madness

Cancer is a prime example of a disease process in which carcinogenic and metabolic changes are intertwined to promote cell survival and growth. One approach to unravel this complex relationship is by studying rare, monogenic disorders caused by mutations in genes encoding metabolic enzymes or regulators. There are hundreds of these diseases, most of which manifest in childhood and are collectively termed 'inborn errors of metabolism' (IEMs). Several IEMs demonstrate the consequences of chronic, systemic loss of a particular metabolic activity that can result in malignancy. In this Opinion article, we present a conceptual categorization of IEMs associated with cancer and discuss how assessment of these rare diseases might inform us about the biological foundations of common types of cancer and opportunities for cancer diagnosis and therapy.

FOXOs support the metabolic requirements of normal and tumor cells by promoting IDH1 expression

FOXO transcription factors are considered bona fide tumor suppressors; however, recent studies showed FOXOs are also required for tumor survival. Here, we identify FOXOs as transcriptional activators of IDH1. FOXOs promote IDH1 expression and thereby maintain the cytosolic levels of α-ketoglutarate and NADPH. In cancer cells carrying mutant IDH1, FOXOs likewise stimulate mutant IDH1 expression and maintain the levels of the oncometabolite 2-hydroxyglutarate, which stimulates cancer cell proliferation and inhibits TET enzymes and histone demethylases. Combined, our data provide a new paradigm for the paradoxical role of FOXOs in both tumor suppression and promotion.

Genomic discoveries in adult astrocytoma

Astrocytomas are the most common glial tumor of the central nervous system. Within this category, glioblastoma is the most prevalent and malignant primary brain tumor. Glioblastoma can arise de novo, or through progression from lower-grade lesions, but is uniformly associated with poor outcomes despite surgical resection, chemotherapy, and radiation therapy. Recent genomic discoveries have provided new insight into gliomagenesis and have identified key genetic alterations that have diagnostic, prognostic and predictive capacity. Numerous molecular classification schemes have been proposed to sort tumors into clinically meaningful categories to guide treatment. However, creating therapy targeted towards these alterations has been made challenging by the redundancy of essential signal transduction pathways affected in these tumors, intratumoral heterogeneity, and the hypermutated profiles of recurrent tumors. Future treatment strategies will require a personalized approach with consideration of the unique genetic profile of a specific tumor and the use of multimodality therapies.

Accumulation of 2-hydroxyglutarate in gliomas correlates with survival: a study by 3.0-tesla magnetic resonance spectroscopy

INTRODUCTION

Previous magnetic resonance spectroscopy (MRS) and mass spectroscopy studies have shown accumulation of 2-hydroxyglutarate (2HG) in mutant isocitrate dehydrogenase (IDH) gliomas. IDH mutation is known to be a powerful positive prognostic marker in malignant gliomas. Hence, 2HG accumulation in gliomas was assumed to be a positive prognostic factor in gliomas, but this has not yet been proven. Here, we analyzed 52 patients harboring World Health Organization (WHO) grade II and III gliomas utilizing 3.0-tesla MRS.

RESULTS

Mutant IDH gliomas showed significantly higher accumulation of 2HG (median 5.077 vs. 0.000, p =0.0002, Mann-Whitney test). 2HG was detectable in all mutant IDH gliomas, whereas in 10 out of 27 (37.0%) wild-type IDH gliomas, 2HG was below the detectable range (2HG =0) (p =0.0003, chi-squared test). Screening for IDH mutation by 2HG analysis was highly sensitive (cutoff 2HG =1.489 mM, sensitivity 100.0%, specificity 72.2%). Gliomas with high 2HG accumulation had better overall survival than gliomas with low 2HG accumulation (p =0.0401, Kaplan-Meier analysis).

DISCUSSION

2HG accumulation detected by 3.0-tesla MRS not only correlates well with IDH status, but also positively correlates with survival in WHO grade II and III gliomas.

Action at a distance: allostery and the development of drugs to target cancer cell metabolism

Cancer cells must carefully regulate their metabolism to maintain growth and division under varying nutrient and oxygen levels. Compelling data support the investigation of numerous enzymes as therapeutic targets to exploit metabolic vulnerabilities common to several cancer types. We discuss the rationale for developing such drugs and review three targets with central roles in metabolic pathways crucial for cancer cell growth: pyruvate kinase muscle isozyme splice variant 2 (PKM2) in glycolysis, glutaminase in glutaminolysis, and mutations in isocitrate dehydrogenase 1 and 2 isozymes (IDH1/2) in the tricarboxylic acid cycle. These targets exemplify the drugging approach to cancer metabolism, with allosteric modulation being the common theme. The first glutaminase and mutant IDH1/2 inhibitors have entered clinical testing, and early data are promising. Cancer metabolism provides a wealth of novel targets, and targeting allosteric sites promises to yield selective drugs with the potential to transform clinical outcomes across many cancer types.

Molecular basis of mast cell disease

Mastocytosis is an incurable and sometimes fatal haematological disorder grossly described as the accumulation of abnormal mast cells in the bone marrow and other organs causing tissue and organ damage. The clinical manifestations of this disease are extremely variable; disease phenotypes range from indolent to aggressive, and often present with associated non-mast cell haematological disorders (AHNMD), mainly myeloproliferative neoplasm and myelodysplastic syndromes. Recent efforts to genetically dissect the mechanisms that define aggressive and non-aggressive mastocytosis have generated a list of recurrent somatic mutations in mastocytosis patients that are associated with and may predict the evolution towards aggressive disease phenotypes. Here we review these mutations and discuss the molecular mechanisms associated with these mutations in an effort to better understand the biology of this disease and to predict its onset and evolution, with the ultimate goal of devising new and improved treatment strategies.

Hypoxia signaling pathways in cancer metabolism: the importance of co-selecting interconnected physiological pathways

Both tumor hypoxia and dysregulated metabolism are classical features of cancer. Recent analyses have revealed complex interconnections between oncogenic activation, hypoxia signaling systems and metabolic pathways that are dysregulated in cancer. These studies have demonstrated that rather than responding simply to error signals arising from energy depletion or tumor hypoxia, metabolic and hypoxia signaling pathways are also directly connected to oncogenic signaling mechanisms at many points. This review will summarize current understanding of the role of hypoxia inducible factor (HIF) in these networks. It will also discuss the role of these interconnected pathways in generating the cancer phenotype; in particular, the implications of switching massive pathways that are physiologically 'hard-wired’ to oncogenic mechanisms driving cancer.