Trans vs. cis: a computational study of enasidenib resistance due to IDH2 mutations.

Isocitrate dehydrogenase 2 (IDH2) is a homodimeric enzyme that plays an important role in energy production. A mutation R140Q in one monomer makes the enzyme tumourigenic. Enasidenib is an effective inhibitor of IDH2/R140Q. A secondary mutation Q316E leads to enasidenib resistance. This mutation was hitherto only found in trans, i.e. where one monomer has the R140Q mutation and the other carries the Q316E mutation. It is not clear if the mutation only leads to resistance when in trans or if it has been discovered in trans only by chance, since it was only reported in two patients. Using molecular dynamics (MD) simulations we show that the binding of enasidenib to IDH2 is indeed much weaker when the Q316E mutation takes place in trans not in cis, which provides a molecular explanation for the clinical finding. This is corroborated by non-covalent interaction (NCI) analysis and DFT calculations. Whereas the MD simulations show a loss of one hydrogen bond upon the resistance mutation, NCI and energy decomposition analysis (EDA) reveal that a multitude of interactions are weakened.

3D-QSAR, Scaffold Hopping, Virtual Screening, and Molecular Dynamics Simulations of Pyridin-2-one as mIDH1 Inhibitors.

Isocitrate dehydrogenase 1 (IDH1) is a necessary enzyme for cellular respiration in the tricarboxylic acid cycle. Mutant isocitrate dehydrogenase 1 (mIDH1) has been detected overexpressed in a variety of cancers. mIDH1 inhibitor ivosidenib (AG-120) was only approved by the Food and Drug Administration (FDA) for marketing, nevertheless, a range of resistance has been frequently reported. In this study, several mIDH1 inhibitors with the common backbone pyridin-2-one were explored using the three-dimensional structure-activity relationship (3D-QSAR), scaffold hopping, absorption, distribution, metabolism, excretion (ADME) prediction, and molecular dynamics (MD) simulations. Comparative molecular field analysis (CoMFA, R2 = 0.980, Q2 = 0.765) and comparative molecular similarity index analysis (CoMSIA, R2 = 0.997, Q2 = 0.770) were used to build 3D-QSAR models, which yielded notably decent predictive ability. A series of novel structures was designed through scaffold hopping. The predicted pIC50 values of C3, C6, and C9 were higher in the model of 3D-QSAR. Additionally, MD simulations culminated in the identification of potent mIDH1 inhibitors, exhibiting strong binding interactions, while the analyzed parameters were free energy landscape (FEL), radius of gyration (Rg), solvent accessible surface area (SASA), and polar surface area (PSA). Binding free energy demonstrated that C2 exhibited the highest binding free energy with IDH1, which was -93.25 ± 5.20 kcal/mol. This research offers theoretical guidance for the rational design of novel mIDH1 inhibitors.

Mutations in glioblastoma proteins do not disrupt epitope presentation and recognition, maintaining a specific CD8 T cell immune response potential.

Antigen-specific cytotoxic CD8 T cells are extremely effective in controlling tumor growth and have been the focus of immunotherapy approaches. We leverage in silico tools to investigate whether the occurrence of mutations in proteins previously described as immunogenic and highly expressed by glioblastoma multiforme (GBM), such as Epidermal Growth Factor Receptor (EGFR), Isocitrate Dehydrogenase 1 (IDH1), Phosphatase and Tensin homolog (PTEN) and Tumor Protein 53 (TP53), may be contributing to the differential presentation of immunogenic epitopes. We recovered Class I MHC binding information from wild-type and mutated proteins using the Immune Epitope Database (IEDB). After that, we built peptide-MHC (pMHC-I) models in HLA-arena, followed by hierarchical clustering analysis based on electrostatic surface features from each complex. We identified point mutations that are determinants for the presentation of a set of peptides from TP53 protein. We point to structural features in the pMHC-I complexes of wild-type and mutated peptides, which may play a role in the recognition of CD8 T cells. To further explore these features, we performed 100 ns molecular dynamics simulations for the peptide pairs (wt/mut) selected. In pursuit of novel therapeutic targets for GBM treatment, we selected peptides where our predictive results indicated that mutations would not disrupt epitope presentation, thereby maintaining a specific CD8 T cell immune response. These peptides hold potential for future GBM interventions, including peptide-based or mRNA vaccine development applications.

Natural and synthetic 2-oxoglutarate derivatives are substrates for oncogenic variants of human isocitrate dehydrogenase 1 and 2.

Variants of isocitrate dehydrogenase (IDH) 1 and 2 (IDH1/2) alter metabolism in cancer cells by catalyzing the NADPH-dependent reduction of 2-oxoglutarate (2OG) to (2R)-hydroxyglutarate. However, it is unclear how derivatives of 2OG can affect cancer cell metabolism. Here, we used synthetic C3- and C4-alkylated 2OG derivatives to investigate the substrate selectivities of the most common cancer-associated IDH1 variant (R132H IDH1), of two cancer-associated IDH2 variants (R172K IDH2, R140Q IDH2), and of WT IDH1/2. Absorbance-based, NMR, and electrochemical assays were employed to monitor WT IDH1/2 and IDH1/2 variant-catalyzed 2OG derivative turnover in the presence and absence of 2OG. Our results reveal that 2OG derivatives can serve as substrates of the investigated IDH1/2 variants, but not of WT IDH1/2, and have the potential to act as 2OG-competitive inhibitors. Kinetic parameters reveal that some 2OG derivatives, including the natural product 3-methyl-2OG, are equally or even more efficient IDH1/2 variant substrates than 2OG. Furthermore, NMR and mass spectrometry studies confirmed IDH1/2 variant-catalyzed production of alcohols in the cases of the 3-methyl-, 3-butyl-, and 3-benzyl-substituted 2OG derivatives; a crystal structure of 3-butyl-2OG with an IDH1 variant (R132C/S280F IDH1) reveals active site binding. The combined results highlight the potential for (i) IDH1/2 variant-catalyzed reduction of 2-oxoacids other than 2OG in cells, (ii) modulation of IDH1/2 variant activity by 2-oxoacid natural products, including some present in common foods, (iii) inhibition of IDH1/2 variants via active site binding rather than the established allosteric mode of inhibition, and (iv) possible use of IDH1/2 variants as biocatalysts.

From a dimer to a monomer: Construction of a chimeric monomeric isocitrate dehydrogenase.

Many isocitrate dehydrogenases (IDHs) are dimeric enzymes whose catalytic sites are located at the intersubunit interface, whereas monomeric IDHs form catalytic sites with single polypeptide chains. It was proposed that monomeric IDHs were evolved from dimeric ones by partial gene duplication and fusion, but the evolutionary process had not been reproduced in laboratory. To construct a chimeric monomeric IDH from homo-dimeric one, it is necessary to reconstitute an active center by a duplicated region; to properly link the duplicated region to the rest part; and to optimize the newly formed protein surface. In this study, a chimeric monomeric IDH was successfully constructed by using homo-dimeric Escherichia coli IDH as a start point by rational design and site-saturation mutagenesis. The ~67 kDa chimeric enzyme behaved as a monomer in solution, with a Km of 61 µM and a kcat of 15 s-1 for isocitrate in the presence of NADP+ and Mn2+ . Our result demonstrated that dimeric IDHs have a potential to evolve monomeric ones. The evolution of the IDH family was also discussed.

Structural engineering of chimeric antigen receptors targeting HLA-restricted neoantigens.

Chimeric antigen receptor (CAR) T cells have emerged as a promising class of therapeutic agents, generating remarkable responses in the clinic for a subset of human cancers. One major challenge precluding the wider implementation of CAR therapy is the paucity of tumor-specific antigens. Here, we describe the development of a CAR targeting the tumor-specific isocitrate dehydrogenase 2 (IDH2) with R140Q mutation presented on the cell surface in complex with a common human leukocyte antigen allele, HLA-B*07:02. Engineering of the hinge domain of the CAR, as well as crystal structure-guided optimization of the IDH2R140Q-HLA-B*07:02-targeting moiety, enhances the sensitivity and specificity of CARs to enable targeting of this HLA-restricted neoantigen. This approach thus holds promise for the development and optimization of immunotherapies specific to other cancer driver mutations that are difficult to target by conventional means.

Low pH Facilitates Heterodimerization of Mutant Isocitrate Dehydrogenase IDH1-R132H and Promotes Production of 2-Hydroxyglutarate.

Isocitrate dehydrogenase 1 (IDH1) is a key metabolic enzyme for maintaining cytosolic levels of α-ketoglutarate (AKG) and preserving the redox environment of the cytosol. Wild-type (WT) IDH1 converts isocitrate to AKG; however, mutant IDH1-R132H that is recurrent in human cancers catalyzes the neomorphic production of the oncometabolite d-2-hydroxyglutrate (D-2HG) from AKG. Recent work suggests that production of l-2-hydroxyglutarte in cancer cells can be regulated by environmental changes, including hypoxia and intracellular pH (pHi). However, it is unknown whether and how pHi affects the activity of IDH1-R132H. Here, we show that in cells IDH1-R132H can produce D-2HG in a pH-dependent manner with increased production at lower pHi. We also identify a molecular mechanism by which this pH sensitivity is achieved. We show that pH-dependent production of D-2HG is mediated by pH-dependent heterodimer formation between IDH1-WT and IDH1-R132H. In contrast, neither IDH1-WT nor IDH1-R132H homodimer formation is affected by pH. Our results demonstrate that robust production of D-2HG by IDH1-R132H relies on the coincidence of (1) the ability to form heterodimers with IDH1-WT and (2) low pHi or highly abundant AKG substrate. These data suggest cancer-associated IDH1-R132H may be sensitive to physiological or microenvironmental cues that lower pH, such as hypoxia or metabolic reprogramming. This work reveals new molecular considerations for targeted therapeutics and suggests potential synergistic effects of using catalytic IDH1 inhibitors targeting D-2HG production in combination with drugs targeting the tumor microenvironment.

Assessing acquired resistance to IDH1 inhibitor therapy by full-exon IDH1 sequencing and structural modeling.

Somatic mutations in hotspot regions of the cytosolic or mitochondrial isoforms of the isocitrate dehydrogenase gene (IDH1 and IDH2, respectively) contribute to the pathogenesis of acute myeloid leukemia (AML) by producing the oncometabolite 2-hydroxyglutarate (2-HG). The allosteric IDH1 inhibitor, ivosidenib, suppresses 2-HG production and induces clinical responses in relapsed/refractory IDH1-mutant AML. Herein, we describe a clinical case of AML in which we detected the neomorphic IDH1 p.R132C mutation in consecutive patient samples with a mutational hotspot targeted next-generation sequencing (NGS) assay. The patient had a clinical response to ivosidenib, followed by relapse and disease progression. Subsequent sequencing of the relapsed sample using a newly developed all-exon, hybrid-capture-based NGS panel identified an additional IDH1 p.S280F mutation known to cause renewed 2-HG production and drug resistance. Structural modeling confirmed that serine-to-phenylalanine substitution at this codon sterically hinders ivosidenib from binding to the mutant IDH1 dimer interface and predicted a similar effect on the pan-IDH inhibitor AG-881. Joint full-exon NGS and structural modeling enables monitoring IDH1 inhibitor-treated AML patients for acquired drug resistance and choosing follow-up therapy.

Role of traditional CHO PET parameters in distinguishing IDH, TERT and MGMT alterations in primary diffuse gliomas.

OBJECTIVE: Isocitrate dehydrogenase (IDH) mutation, telomerase reverse transcriptase (TERT) promoter mutation and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status are diagnostic, prognostic, predictive and therapeutic biomarkers for primary diffuse gliomas, and this study aimed to explore the relationship between choline (CHO) positron emission tomography (PET) parameters and these molecular alterations. METHODS: Twenty-eight patients who were histopathologically diagnosed with primary diffuse glioma and underwent presurgical CHO PET/CT were retrospectively analyzed, and IDH, TERT and MGMT alterations were examined. The volume of interest (VOI) was semiautomatically defined based on standardized uptake value (SUV) thresholds, and 5 traditional CHO parameters, namely, SUVmax, SUVmean, metabolic tumor volume (MTV), total lesion CHO uptake (TLC) and tumor-to-normal contralateral cortex activity ratio (T/N ratio), were calculated. Wilcoxon rank-sum tests and receiver operating characteristic (ROC) curves were applied to evaluate the differences and performances of the CHO parameters, and their capability to stratify patient prognosis was also evaluated. RESULTS: All 5 parameters were significantly higher in IDH-wildtype gliomas than in IDH-mutant gliomas (p = 0.0001-0.037), and SUVmax, SUVmean, TLC and the T/N ratio exhibited good performances in distinguishing the IDH status (areas under the ROC curve (AUCs) 0.856-0.918, accuracies 0.857-0.893) as well as stratifying patient prognosis. Although the differences and performances of the traditional parameters in distinguishing diverse TERT and MGMT statuses were moderate in the whole population, the T/N ratio and TLC displayed certain predictive value in discriminating the TERT status in the IDH-mutant and IDH-wildtype subgroups (p = 0.028-0.048, AUCs 0.857-0.860, accuracies 0.800-0.917, respectively). CONCLUSIONS: Traditional CHO PET parameters are capable of distinguishing IDH but not TERT or MGMT alterations in the whole population. In accordance with the clinical understanding of TERT promoter mutations, the T/N ratio and TLC can also discriminate the TERT status in IDH subgroups.

Dysregulation of the Sirt5/IDH2 axis contributes to sunitinib resistance in human renal cancer cells.

Sunitinib (Sun), a tyrosine kinase inhibitor of vascular endothelial growth factor receptor, is the standard first-line treatment against advanced clear cell renal cell carcinoma (RCC), but resistance to therapy is inevitable. Reactive oxygen species production is associated with sensitivity to chemotherapy, but the underlying mechanisms are not completely understood. Here, we investigated the mechanisms contributing to Sun resistance using the RCC cell lines ACHN and 786-O. We report that Sun-resistant cells exhibited reduced apoptosis, increased cell viability, increased reactive oxygen species production and disrupted mitochondrial function. Furthermore, chronic Sun treatment resulted in an up-regulation of Sirt5/isocitrate dehydrogenase 2 (IDH2) expression levels. Knockdown of Sirt5/IDH2 impaired mitochondrial function and partially attenuated Sun resistance. Finally, up-regulation of Sirt5 enhanced the expression of IDH2 via modulation of succinylation at K413 and promoted protein stability. In conclusion, dysregulation of Sirt5/IDH2 partially contributes to Sun resistance in RCC cells by affecting antioxidant capacity.

Chiral discrimination in a mutated IDH enzymatic reaction in cancer: a computational perspective.

Chiral discrimination in biological systems, such as L-amino acids in proteins and d-sugars in nucleic acids, has been proposed to depend on various mechanisms, and chiral discrimination by mutated enzymes mediating cancer cell signaling is important in current research. We have explored how mutated isocitrate dehydrogenase (IDH) catalyzes the oxidative decarboxylation of isocitrate to α-ketoglutarate which in turn is converted to d-2-hydroxyglutatrate (d-2HG) as a preferred product instead of l-2-hydroxyglutatrate (l-2HG) according to quantum chemical calculations. Using transition state structure modeling, we delineate the preferred product formation of d-2HG over l-2HG in an IDH active site model. The mechanisms for the formation of d-2HG over l-2HG are assessed by identifying transition state structures and activation energy barriers in gas and solution phases. The calculated reaction energy profile for the formation of d-2HG and l-2HG metabolites shows a 29 times higher value for l-2HG as compared to d-2HG. Results for second-order Møller-Plesset perturbation theory (MP2) do not alter the observed trend based on Density Functional Theory (DFT). The observed trends in reaction energy profile explain why the formation of D-2HG is preferred over l-2HG and reveal why mutation leads to the formation of d-2HG instead of l-2HG. For a better understanding of the observed difference in the activation barrier for the formation of the two alternative products, we performed natural bond orbital analysis, non-covalent interactions analysis and energy decomposition analysis. Our findings based on computational calculations clearly indicate a role for chiral discrimination in mutated enzymatic pathways in cancer biology.

An acidic residue buried in the dimer interface of isocitrate dehydrogenase 1 (IDH1) helps regulate catalysis and pH sensitivity.

Isocitrate dehydrogenase 1 (IDH1) catalyzes the reversible NADP+-dependent conversion of isocitrate to α-ketoglutarate (αKG) to provide critical cytosolic substrates and drive NADPH-dependent reactions like lipid biosynthesis and glutathione regeneration. In biochemical studies, the forward reaction is studied at neutral pH, while the reverse reaction is typically characterized in more acidic buffers. This led us to question whether IDH1 catalysis is pH-regulated, which would have functional implications under conditions that alter cellular pH, like apoptosis, hypoxia, cancer, and neurodegenerative diseases. Here, we show evidence of catalytic regulation of IDH1 by pH, identifying a trend of increasing kcat values for αKG production upon increasing pH in the buffers we tested. To understand the molecular determinants of IDH1 pH sensitivity, we used the pHinder algorithm to identify buried ionizable residues predicted to have shifted pKa values. Such residues can serve as pH sensors, with changes in protonation states leading to conformational changes that regulate catalysis. We identified an acidic residue buried at the IDH1 dimer interface, D273, with a predicted pKa value upshifted into the physiological range. D273 point mutations had decreased catalytic efficiency and, importantly, loss of pH-regulated catalysis. Based on these findings, we conclude that IDH1 activity is regulated, at least in part, by pH. We show this regulation is mediated by at least one buried acidic residue ∼12 Å from the IDH1 active site. By establishing mechanisms of regulation of this well-conserved enzyme, we highlight catalytic features that may be susceptible to pH changes caused by cell stress and disease.

Structure-based design, synthesis and bioactivity evaluation of macrocyclic inhibitors of mutant isocitrate dehydrogenase 2 (IDH2) displaying activity in acute myeloid leukemia cells.

The enzymes involved in the metabolic pathways in cancer cells have been demonstrated as important therapeutic targets such as the isocitrate dehydrogenase 2 (IDH2). A series of macrocyclic derivatives was designed based on the marketed IDH2 inhibitor AG-221 by using the conformational restriction strategy. The resulted compounds showed moderate to good inhibitory potential against different IDH2-mutant enzymes. Amongst, compound C6 exhibited better IDH2R140Q inhibitory potency than AG-221, and showed excellent activity of 2-hydroxyglutarate (2-HG) suppression in vitro and its mesylate displayed good pharmacokinetic profiles. Moreover, C6 performed strong binding mode to IDH2R140Q after computational docking and dynamic simulation, which may serve as a good starting point for further development.

Molecular modeling studies to discover novel mIDH2 inhibitors with high selectivity for the primary and secondary mutants.

Mutant isocitrate dehydrogenase 2 (mIDH2) is an emerging target for the treatment of cancer. AG-221 is the first mIDH2 inhibitor approved by the FDA for acute myeloid leukemia treatment, but its acquired resistance has recently been observed, necessitating the development of new inhibitor. In this study, a multi-step virtual screening protocol was employed for the analysis of a large database of compounds to identify potential mIDH2 inhibitors. To this end, we firstly utilized molecular dynamics (MD) simulations and binding free energy calculations to elucidate the key factors affecting ligand binding and drug resistance. Based on these findings, the receptor-ligand interaction-based pharmacophore (IBP) model and hierarchical docking-based virtual screening were sequentially carried out to assess 212,736 compounds from the Specs database. The resulting hits were finally ranked by PAINS filter and ADME prediction and the top compounds were obtained. Among them, six molecules were identified as mIDH2 putative inhibitors with high selectivity by interacting with the capping residue Asp312. Furthermore, subsequent docking and MD experiments demonstrated that compound V2 might have potential inhibitory activity against the AG-221-resistant mutants, thereby making it a promising lead for the development of novel mIDH2 inhibitors.

A high-throughput SAMDI-mass spectrometry assay for isocitrate dehydrogenase 1.

The enzyme isocitrate dehydrogenase 1 (IDH1) catalyzes the conversion of isocitrate to alpha-ketoglutarate (αKG) and has emerged as an important therapeutic target for glioblastoma multiforme (GBM). Current methods for assaying IDH1 remain poorly suited for high-throughput screening of IDH1 antagonists. This paper describes a high-throughput and quantitative assay for IDH1 that is based on the self-assembled monolayers for matrix-assisted laser desorption/ionization-mass spectrometry (SAMDI-MS) method. The assay uses a self-assembled monolayer presenting a hydrazide group that covalently captures the αKG product of IDH1, where it can then be detected by MALDI-TOF mass spectrometry. Co-capture of an isotopically-labeled αKG internal standard allows the αKG concentration to be quantitated. The assay was used to analyze a series of standard αKG solutions and produced minimal error in measured αKG concentration values. The suitability of the assay for high-throughput analysis was evaluated in a 384-sample biochemical IDH1 screen. Cells expressing IDH1 were lysed and the lysate was applied to the monolayer to capture αKG, which was then quantitated using the SAMDI-MS assay. Cells in which IDH1 expression was reduced by small-interfering RNA exhibited a corresponding decrease in αKG concentration as measured by the assay. Application of the assay toward the high-throughput screening of IDH1 inhibitors or knockdown agents may facilitate the discovery of treatments for GBM.

Interaction between IDH1 WT and calmodulin and its implications for glioblastoma cell growth and migration.

Isocitrate dehydrogenase (IDH) mutations are found in low-grade gliomas, and the product of the IDH mutant (MT), 2-hydroxyglutarate (2-HG), is the first known oncometabolite. However, the roles of the IDH wild type (WT) in high-grade glioblastoma, which rarely has the IDH mutation, are still unknown. To investigate possible pathways related to IDH WT in gliomas, we carried out bioinformatics analysis, and found that IDH1 has several putative calmodulin (CaM) binding sites. Pull-down and quantitative dissociation constant (Kd) measurements using recombinant proteins showed that IDH1 WT indeed binds to CaM with a higher affinity than IDH1 R132H MT. This biochemical interaction was demonstrated also in the cellular environment by immunoprecipitation with glioblastoma cell extracts. A synthetic peptide for the suggested binding region interfered with the interaction between CaM and IDH1, confirming the specificity of the binding. Direct binding between the synthetic peptide and CaM was observed in an NMR binding experiment, which additionally revealed that the peptide initially binds to the C-lobe of CaM. The physiological meaning of the CaM-IDH1 WT binding was shown with trifluoperazine (TFP), a CaM antagonist, which disrupted the binding and inhibited survival and migration of glioblastoma cells with IDH1 WT. As CaM signaling is activated in glioblastoma, our results suggest that IDH1 WT may be involved in the CaM-signaling pathway in the tumorigenesis of high-grade gliomas.

Water Networks and Correlated Motions in Mutant Isocitrate Dehydrogenase 1 (IDH1) Are Critical for Allosteric Inhibitor Binding and Activity.

Point mutations in human isocitrate dehydrogenase 1 (IDH1) can drive malignancies, including lower-grade gliomas and secondary glioblastomas, chondrosarcomas, and acute myeloid leukemias. These mutations, which usually affect residue R132, ablate the normal activity of catalyzing the NADP+-dependent oxidation of isocitrate to α-ketoglutarate (αKG) while also acquiring a neomorphic activity of reducing αKG to d-2-hydroxyglutarate (D2HG). Mutant IDH1 can be selectively therapeutically targeted due to structural differences that occur in the wild type (WT) versus mutant form of the enzyme, though the full mechanisms of this selectivity are still under investigation. Here we probe the mechanistic features of the neomorphic activity and selective small molecule inhibition through a new lens, employing WaterMap and molecular dynamics simulations. These tools identified a high-energy path of water molecules connecting the inhibitor binding site with the αKG and NADP+ binding sites in mutant IDH1. This water path aligns spatially with the α10 helix from WT IDH1 crystal structures. Mutating residues at the termini of this water path specifically disrupted inhibitor binding and/or D2HG production, revealing additional key residues to consider in optimizing druglike molecules against mutant IDH1. Taken together, our findings from molecular simulations and mutant enzyme kinetic assays provide insight into how disrupting water paths through enzyme active sites can impact not only inhibitor potency but also substrate recognition and activity.

Identification of High-Affinity Small Molecule Targeting IDH2 for the Clinical Treatment of Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is symbolized by an increase in the number of myeloid cells in the bone marrow and an arrest in their maturation, frequently resulting in hematopoietic insufficiency (granulocytopenia, thrombocytopenia, or anemia) with or without leukocytosis either by a predominance of immature forms or a loss of normal hematopoiesis. IDH2 gene encodes for isocitrate dehydrogenase enzyme which is involved in the TCA cycle domino effect and converts isocitrate to alpha-ketoglutarate. In the U.S, the annual incidence of AML progressively increases with age to a peak of 12.6 per 100,000 adults of 65 years or older. Mutations in isocitrate dehydrogenase 2 (arginine 132) have been demonstrated to be recurrent gene alterations in acute myeloid leukemia (AML) by forming 2-Hydroxy alpha ketoglutarate which, instead of participating in TCA cycle, accumulates to form AML. The current study approaches by molecular docking and virtual screening to elucidate inhibitor with superior affinity against IDH2 and achieve a pharmacological profile. To obtain the best established drug Molegro Virtual Docker algorithm was executed. The compound AG-221 (Pub CID 71299339) having the high affinity score was subjected to similarity search to retrieve the drugs with similar properties. The virtual screened compound SCHEMBL16391748 (PubChem CID-117816179) shows high affinity for the protein. Comparative study and ADMET study for both the above compounds resulted in equivalent chemical properties. Virtual screened compound SCHEMBL16391748 (PubChem CID-117816179) shows the lowest re-rank score. These drugs are identified as high potential IDH2 inhibitors and can halt AML when validated through further In vitro screening.

Pharmacological characterization of TQ05310, a potent inhibitor of isocitrate dehydrogenase 2 R140Q and R172K mutants.

Isocitrate dehydrogenase 2 (IDH2), an important mitochondrial metabolic enzyme involved in the tricarboxylic acid cycle, is mutated in a variety of cancers. AG-221, an inhibitor primarily targeting the IDH2-R140Q mutant, has shown remarkable clinical benefits in the treatment of relapsed or refractory acute myeloid leukemia patients. However, AG-221 has weak inhibitory activity toward IDH2-R172K, a mutant form of IDH2 with more severe clinical manifestations. Herein, we report TQ05310 as the first mutant IDH2 inhibitor that potently targets both IDH2-R140Q and IDH2-R172K mutants. TQ05310 inhibited mutant IDH2 enzymatic activity, suppressed (R)-2-hydroxyglutarate (2-HG) production and induced differentiation in cells expressing IDH2-R140Q and IDH2-R172K, but not in cells expressing wild-type IDH1/2 or mutant IDH1. TQ05310 bound to both IDH2-R140Q and IDH2-R172K, with Q316 being the critical residue mediating the binding of TQ05310 with IDH2-R140Q, but not with IDH2-R172K. TQ05310 also had favorable pharmacokinetic characteristics and profoundly inhibited 2-HG production in a tumor xenografts model. The results of the current study establish a solid foundation for further clinical investigation of TQ05310, and provide new insight into the development of novel mutant IDH2 inhibitors.

Kinase Networks Regulate Metabolism: I'D(H1) Never Have Guessed!

Mutations in isoforms of isocitrate dehydrogenase (IDH) enzymes are described in multiple cancers and both mutant and wild-type IDH are important for the generation and maintenance of tumors, but how their activity is regulated is poorly understood. An article in this issue of Cancer Discovery identifies a novel posttranslational mechanism of IDH1 regulation involving phosphorylation of specific tyrosine residues by a network of kinases that alter the specificity of substrate and cofactor binding, dimer formation, and ultimately enzyme activity.See related article by Chen et al., p. 756.