Discovery and Optimization of Allosteric Inhibitors of Mutant Isocitrate Dehydrogenase 1 (R132H IDH1) Displaying Activity in Human Acute Myeloid Leukemia Cells

Discovery of a septin-4 covalent binder with antimetastatic activity in a mouse model of melanoma

Cancer spreading through metastatic processes is one of the major causes of tumour-related mortality. Metastasis is a complex phenomenon which involves multiple pathways ranging from cell metabolic alterations to changes in the biophysical phenotype of cells and tissues. In the search for new effective anti-metastatic agents, we modulated the chemical structure of the lead compound AA6, in order to find the structural determinants of activity, and to identify the cellular target responsible of the downstream anti-metastatic effects observed. New compounds synthesized were able to inhibit in vitro B16-F10 melanoma cell invasiveness, and one selected compound, CM365, showed in vivo anti-metastatic effects in a lung metastasis mouse model of melanoma. Septin-4 was identified as the most likely molecular target responsible for these effects. This study showed that CM365 is a promising molecule for metastasis prevention, remarkably effective alone or co-administered with drugs normally used in cancer therapy, such as paclitaxel.

Palladium-catalyzed intramolecular aza-Wacker-type cyclization of vinyl cyclopropanecarboxamides to access conformationally restricted aza[3.1.0]bicycles

A palladium(ii)-catalyzed intramolecular oxidative aza-Wacker-type reaction of vinyl cyclopropanecarboxamides to access a series of conformationally restricted highly substituted aza[3.1.0]bicycles is reported. The transformation proceeded through a typical aza-Wacker reaction mechanism to forge a new C-N bond with oxygen as the terminal oxidant. The desired fused heterocycles were obtained in moderate yields. The process is tolerant of a range of functional aryl groups under mild conditions.

Synthesis of 3-Azabicyclo[3.1.0]hexane Derivates

3-Azabicyclo[3.1.0]hexanes are an important class of nitrogen-containing heterocycles that have been found to be key structural features in a wide range of biologically active natural products, drugs, and agrochemicals. As a cutting-edge area, the synthesis of these derivatives has made spectacular progress in recent decades, with various transition-metal-catalyzed and transition-metal-free catalytic systems being developed. In this review, we provide an overview of recent advances in the efficient methods for the synthesis of 3-azabicyclo[3.1.0]hexane derivatives since 2010, emphasizing the scope of substrates and synthesis' applications, as well as the mechanisms of these reactions.

Structure-based discovery of IHMT-IDH1-053 as a potent irreversible IDH1 mutant selective inhibitor

Through a structure-based irreversible drug design approach, we have discovered a highly potent IDH1-mutant inhibitor compound 16 (IHMT-IDH1-053) (IC₅₀ = 4.7 nM), which displays high selectivity against IDH1 mutants over IDH1 wt and IDH2 wt/mutants. The crystal structure demonstrates that 16 binds to the IDH1 R132H protein in the allosteric pocket adjacent to the NAPDH binding pocket through a covalent bond with residue Cys269. 16 inhibits 2-hydroxyglutarate (2-HG) production in IDH1 R132H mutant transfected 293T cells (IC₅₀ = 28 nM). In addition, it inhibits the proliferation of HT1080 cell line and primary AML cells which both bear IDH1 R132 mutants. In vivo, 16 inhibits 2-HG level in a HT1080 xenograft mouse model. Our study suggested that 16 would be a new pharmacological tool to study IDH1 mutant-related pathology and the covalent binding mode provided a novel approach for designing irreversible IDH1 inhibitors.

Challenges for the development of mutant isocitrate dehydrogenases 1 inhibitors to treat glioma

Glioma is one of the most common types of brain tumors, and its high recurrence and mortality rates threaten human health. In 2008, the frequent isocitrate dehydrogenase 1 (IDH1) mutations in glioma were reported, which brought a new strategy in the treatment of this challenging disease. In this perspective, we first discuss the possible gliomagenesis after IDH1 mutations (mIDH1). Subsequently, we systematically investigate the reported mIDH1 inhibitors and present a comparative analysis of the ligand-binding pocket in mIDH1. Additionally, we also discuss the binding features and physicochemical properties of different mIDH1 inhibitors to facilitate the future development of mIDH1 inhibitors. Finally, we discuss the possible selectivity features of mIDH1 inhibitors against WT-IDH1 and IDH2 by combining protein-based and ligand-based information. We hope that this perspective can inspire the development of mIDH1 inhibitors and bring potent mIDH1 inhibitors for the treatment of glioma.

Base-Promoted Intramolecular Addition of Vinyl Cyclopropanecarboxamides to Access Conformationally Restricted Aza[3.1.0]bicycles

3-Azabicyclo[3.1.0]hexanes are common structural components in natural products and bioactive compounds. Traditionally, the metal-mediated cyclopropanation domino reaction of chain enzymes is the most commonly used strategy for the construction of this type of aza[3.1.0]bicycle derivative. In this study, a base-promoted intramolecular addition of alkenes used to deliver conformationally restricted highly substituted aza[3.1.0]bicycles is reported. This reaction was tailor-made for saturated aza[3.1.0] bicycle-containing fused bicyclic compounds that may be applied in the development of concise and divergent total syntheses of bioactive compounds.

The regulatory mechanisms and inhibitors of isocitrate dehydrogenase 1 in cancer

Reprogramming of energy metabolism is one of the basic characteristics of cancer and has been proved to be an important cancer treatment strategy. Isocitrate dehydrogenases (IDHs) are a class of key proteins in energy metabolism, including IDH1, IDH2, and IDH3, which are involved in the oxidative decarboxylation of isocitrate to yield α-ketoglutarate (α-KG). Mutants of IDH1 or IDH2 can produce d-2-hydroxyglutarate (D-2HG) with α-KG as the substrate, and then mediate the occurrence and development of cancer. At present, no IDH3 mutation has been reported. The results of pan-cancer research showed that IDH1 has a higher mutation frequency and involves more cancer types than IDH2, implying IDH1 as a promising anti-cancer target. Therefore, in this review, we summarized the regulatory mechanisms of IDH1 on cancer from four aspects: metabolic reprogramming, epigenetics, immune microenvironment, and phenotypic changes, which will provide guidance for the understanding of IDH1 and exploring leading-edge targeted treatment strategies. In addition, we also reviewed available IDH1 inhibitors so far. The detailed clinical trial results and diverse structures of preclinical candidates illustrated here will provide a deep insight into the research for the treatment of IDH1-related cancers.

Disabling Uncompetitive Inhibition of Oncogenic IDH Mutations Drives Acquired Resistance

Mutations in IDH genes occur frequently in acute myeloid leukemia (AML) and other human cancers to generate the oncometabolite R-2HG. Allosteric inhibition of mutant IDH suppresses R-2HG production in a subset of patients with AML; however, acquired resistance emerges as a new challenge, and the underlying mechanisms remain incompletely understood. Here we establish isogenic leukemia cells containing common IDH oncogenic mutations by CRISPR base editing. By mutational scanning of IDH single amino acid variants in base-edited cells, we describe a repertoire of IDH second-site mutations responsible for therapy resistance through disabling uncompetitive enzyme inhibition. Recurrent mutations at NADPH binding sites within IDH heterodimers act in cis or trans to prevent the formation of stable enzyme-inhibitor complexes, restore R-2HG production in the presence of inhibitors, and drive therapy resistance in IDH-mutant AML cells and patients. We therefore uncover a new class of pathogenic mutations and mechanisms for acquired resistance to targeted cancer therapies.

SIGNIFICANCE

Comprehensive scanning of IDH single amino acid variants in base-edited leukemia cells uncovers recurrent mutations conferring resistance to IDH inhibition through disabling NADPH-dependent uncompetitive inhibition. Together with targeted sequencing, structural, and functional studies, we identify a new class of pathogenic mutations and mechanisms for acquired resistance to IDH-targeting cancer therapies. This article is highlighted in the In This Issue feature, p. 1.

Effects of cancer-associated point mutations on the structure, function, and stability of isocitrate dehydrogenase 2

Mutations in isocitrate dehydrogenase (IDH) are frequently found in low-grade gliomas, secondary glioblastoma, chondrosarcoma, acute myeloid leukemias, and intrahepatic cholangiocarcinoma. However, the molecular mechanisms of how IDH2 mutations induce carcinogenesis remain unclear. Using overlapping PCR, transfection, immunoblotting, immunoprecipitation, measurements of enzyme activity, glucose, lactic acid, ATP, and reactive oxygen species (ROS), cell viability, protein degradation assays post-inhibition of the 26S proteasome (bortezomib) or HSP90 (17-AAG), and a homology model, we demonstrated that the properties of ten cancer-associated IDH2 variants (R140G/Q/W and R172S/K/M/W/G/C/P) arising from point mutations are closely related to their structure and stability. Compared with wild-type IDH2, the R172 and R140 point mutations resulted in a decrease in IDH2 activity, ROS, and lactate levels and an increase in glucose and ATP levels under normal and hypoxic conditions, indicating that mutant IDH2 increases cell dependency on mitochondrial oxidative phosphorylation, and reduces glycolysis under hypoxia. Overexpression of most of IDH2 point mutants showed anti-proliferative effects in the 293T and BV2 cell lines by inhibition of PI3K/AKT signaling and cyclin D1 expression and/or induced the expression of TNF-α and IL-6. Furthermore, bortezomib treatment resulted in dramatic degradation of IDH2 mutants, including R140G, R140Q, R140W, R172S and R172K, whereas it had little impact on the expression of WT and other mutants (R172M, R172W, R172G, R172C and R172P). In addition, targeting HSP90 minimally affected the expression of mutated IDH2 due to a lack of interaction between HSP90 and IDH2. The homology model further revealed that changes in conformation and IDH2 protein stability appeared to be associated with these point mutations. Taken together, our findings provide information important for understanding the molecular mechanisms of IDH2 mutations in tumors.

Recent advances of IDH1 mutant inhibitor in cancer therapy

Isocitrate dehydrogenase (IDH) is the key metabolic enzyme that catalyzes the conversion of isocitrate to α-ketoglutarate (α-KG). Two main types of IDH1 and IDH2 are present in humans. In recent years, mutations in IDH have been observed in several tumors, including glioma, acute myeloid leukemia, and chondrosarcoma. Among them, the frequency of IDH1 mutations is higher than IDH2. IDH1 mutations have been shown to increase the conversion of α-KG to 2-hydroxyglutarate (2-HG). IDH1 mutation-mediated accumulation of 2-HG leads to epigenetic dysregulation, altering gene expression, and impairing cell differentiation. A rapidly emerging therapeutic approach is through the development of small molecule inhibitors targeting mutant IDH1 (mIDH1), as evidenced by the recently approved of the first selective IDH1 mutant inhibitor AG-120 (ivosidenib) for the treatment of IDH1-mutated AML. This review will focus on mIDH1 as a therapeutic target and provide an update on IDH1 mutant inhibitors in development and clinical trials.

Targeting IDH Mutations in AML: Wielding the Double-edged Sword of Differentiation

The genomic characterization of acute myeloid leukemia (AML) by DNA sequencing has illuminated subclasses of the disease, with distinct driver mutations, that might be responsive to targeted therapies. Approximately 15-23% of AML genomes harbor mutations in one of two isoforms of isocitrate dehydrogenase (IDH1 or IDH2). These enzymes are constitutive mediators of basic cellular metabolism, but their mutated forms in cancer synthesize an abnormal metabolite, 2- hydroxyglutarate, that in turn acts as a competitive inhibitor of multiple gene regulatory enzymes. As a result, leukemic IDH mutations cause changes in genome structure and gene activity, culminating in an arrest of normal myeloid differentiation. These discoveries have motivated the development of a new class of selective small molecules with the ability to inhibit the mutant IDH enzymes while sparing normal cellular metabolism. These agents have shown promising anti-leukemic activity in animal models and early clinical trials, and are now entering Phase 3 study. This review will focus on the growing preclinical and clinical data evaluating IDH inhibitors for the treatment of IDH-mutated AML. These data suggest that inducing cellular differentiation is central to the mechanism of clinical efficacy for IDH inhibitors, while also mediating toxicity for patients who experience IDH Differentiation Syndrome. Ongoing trials are studying the efficacy of IDH inhibitors in combination with other AML therapies, both to evaluate potential synergistic combinations as well as to identify the appropriate place for IDH inhibitors within existing standard-of-care regimens.

Construction of Spiro[3-azabicyclo[3.1.0]hexanes] via 1,3-Dipolar Cycloaddition of 1,2-Diphenylcyclopropenes to Ninhydrin-Derived Azomethine Ylides

The multi-component 1,3-dipolar cycloaddition of ninhydrin, α-amino acids (or peptides), and cyclopropenes for the synthesis of spirocyclic heterocycles containing both 3-azabicyclo[3.1.0]hexane and 2H-indene-1,3-dione motifs has been developed. This method provides easy access to 3-azabicyclo[3.1.0]hexane-2,2′-indenes with complete stereoselectivity and a high degree of atom economy under mild reaction conditions. A broad range of cyclopropenes and α-amino acids have been found to be compatible with the present protocol, which offers an opportunity to create a new library of biologically significant scaffold (3-azabicyclo[3.1.0]hexane). In addition, the сomprehensive study of mechanism of azomethine ylide formation from ninhydrin and sarcosine was performed by means of M11 density functional theory (DFT) calculations. It has been revealed that experimentally observed 1-methylspiro[aziridine-2,2′-indene]-1′,3′-dione is a kinetically controlled product of this reaction and appears to act as a 1,3-dipole precursor. This theoretical study also shed light on the main transformations of the azomethine ylide derived from ninhydrin and sarcosine such as a 1,3-dipolar cycloaddition to cyclopropene dipolarophiles, a dimerization reaction and a (1+5) electrocyclization reaction. The antitumor activity of some synthesized compounds against cervical carcinoma (HeLa­) cell line was evaluated in vitro by MTS-assay.

Molecular mechanisms mediating relapse following ivosidenib monotherapy in IDH1-mutant relapsed or refractory AML

Isocitrate dehydrogenase (IDH) 1 and 2 mutations result in overproduction of D-2-hydroxyglutarate (2-HG) and impaired cellular differentiation. Ivosidenib, a targeted mutant IDH1 (mIDH1) enzyme inhibitor, can restore normal differentiation and results in clinical responses in a subset of patients with mIDH1 relapsed/refractory (R/R) acute myeloid leukemia (AML). We explored mechanisms of ivosidenib resistance in 174 patients with confirmed mIDH1 R/R AML from a phase 1 trial. Receptor tyrosine kinase (RTK) pathway mutations were associated with primary resistance to ivosidenib. Multiple mechanisms contributed to acquired resistance, particularly outgrowth of RTK pathway mutations and 2-HG-restoring mutations (second-site IDH1 mutations, IDH2 mutations). Observation of multiple concurrent mechanisms in individual patients underscores the complex biology of resistance and has important implications for rational combination therapy design. This trial was registered at www.clinicaltrials.gov as #NCT02074839.

I-8, a novel inhibitor of mutant IDH1, inhibits cancer progression in vitro and in vivo

Isocitrate dehydrogenase 1 mutations have been discovered in an array of hematologic malignancies and solid tumors. These mutations could cause the production of high levels of 2-hydroxyglutarate, which in turn implicated in epigenetic changes and impaired cell differentiation. Here, we described the characterization of compound I-8, a novel mutant IDH1 inhibitor, both in vitro and in vivo. Compound I-8 specifically inhibited 2-HG production, reduced histone methylation levels, induced differentiation and depleted stem characteristics in engineered and endogenous IDH1 mutant cells. In addition, oral administration of I-8 also significantly suppressed 2-HG production and histone methylation with dose of 150 mg/kg. And I-8 treatment also could induce differentiation and attenuate stem characteristics in tumor tissue. Together, these studies indicated that compound I-8 has clinical potential in tumor therapies as a effective mutant IDH1 inhibitor, and provided scientific guidance for the development of mutant IDH1 inhibitor in the future.

Stereo- and Regioselective 1,3-Dipolar Cycloaddition of the Stable Ninhydrin-Derived Azomethine Ylide to Cyclopropenes: Trapping of Unstable Cyclopropene Dipolarophiles

A stereo- and regioselective 1,3-dipolar cycloaddition of the stable ninhydrin-derived azomethine ylide [2-(3,4-dihydro-2 H-pyrrolium-1-yl)-1-oxo-1 H-inden-3-olate, DHPO] to differently substituted cyclopropenes has been established. As a result, an efficient synthetic protocol was developed for the preparation of biologically relevant spiro[cyclopropa[ a]pyrrolizine-2,2'-indene] derivatives. DHPO has proved to be an effective trap for such highly reactive and unstable substrates as parent cyclopropene, 1-methylcyclopropene, 1-phenylcyclopropene, and 1-halo-2-phenylcyclopropenes. It has also been found that 3-nitro-1,2-diphenylcyclopropene undergoes a nucleophilic substitution reaction in alcohols and thiols to afford 3-alkoxy- and 3-arylthio-substituted 1,2-diphenylcyclopropenes, which can be captured as corresponding 1,3-dipolar cycloadducts in the presence of DHPO. These new approaches provide a straightforward strategy for the synthesis of functionally substituted cyclopropa[ a]pyrrolizine derivatives. The factors governing regio- and stereoselectivity have been revealed by means of quantum mechanical calculations (M11 density functional theory), including previously unreported N_ylide- H_cyclopropene second-orbital interactions. The outcome of this work contributes to the study of 1,3-dipolar cycloaddition, as well as enriches chemistry of cyclopropenes and methods for the construction of polycyclic compounds with cyclopropane fragments.

Synthesis and biological evaluation of 3-aryl-4-indolyl-maleimides as potent mutant isocitrate dehydrogenase-1 inhibitors

A series of 3-aryl-4-indolylmaleimide IDH1/R132H inhibitors with a novel structure was obtained by high-throughput screening and structure-based optimization. Most compounds such as 7a, 7d, 7h, 7i, 7k and 7o showed high inhibitory effects on IDH1/R132H and were highly selective against IDH1/WT, IDH2/WT, GDH, GK, and FBP. Evaluation of the biological activities and function at cellular level showed that compounds 7h, 7i and 7k could effectively suppress the production of 2-hydroxyglutaric acid in U87MG cells expressing IDH1/R132H. Additionally, 7h could reversed the differentiation block of the myeloid leukemic cell line, TF-1, caused by the overexpression of IDH1/R132H. We also explore the structure-activity relationship based on the experimental data, with an attempt to pave the way for future studies.

Inhibitor potency varies widely among tumor-relevant human isocitrate dehydrogenase 1 mutants

Mutations in isocitrate dehydrogenase 1 (IDH1) drive most low-grade gliomas and secondary glioblastomas and many chondrosarcomas and acute myeloid leukemia cases. Most tumor-relevant IDH1 mutations are deficient in the normal oxidization of isocitrate to α-ketoglutarate (αKG), but gain the neomorphic activity of reducing αKG to D-2-hydroxyglutarate (D2HG), which drives tumorigenesis. We found previously that IDH1 mutants exhibit one of two reactivities: deficient αKG and moderate D2HG production (including commonly observed R132H and R132C) or moderate αKG and high D2HG production (R132Q). Here, we identify a third type of reactivity, deficient αKG and high D2HG production (R132L). We show that R132Q IDH1 has unique structural features and distinct reactivities towards mutant IDH1 inhibitors. Biochemical and cell-based assays demonstrate that while most tumor-relevant mutations were effectively inhibited by mutant IDH1 inhibitors, R132Q IDH1 had up to a 16 300-fold increase in IC₅₀ versus R132H IDH1. Only compounds that inhibited wild-type (WT) IDH1 were effective against R132Q. This suggests that patients with a R132Q mutation may have a poor response to mutant IDH1 therapies. Molecular dynamics simulations revealed that near the NADP⁺/NADPH-binding site in R132Q IDH1, a pair of α-helices switches between conformations that are more wild-type-like or more mutant-like, highlighting mechanisms for preserved WT activity. Dihedral angle changes in the dimer interface and buried surface area charges highlight possible mechanisms for loss of inhibitor affinity against R132Q. This work provides a platform for predicting a patient's therapeutic response and identifies a potential resistance mutation that may arise upon treatment with mutant IDH inhibitors.

3-(7-Azaindolyl)-4-indolylmaleimides as a novel class of mutant isocitrate dehydrogenase-1 inhibitors: Design, synthesis, and biological evaluation

A series of 3-(7-azainodyl)-4-indolylmaleimides was designed, synthesized, and evaluated for their isocitrate dehydrogenase 1 (IDH1)/R132H inhibitory activities. Many compounds such as 11a, 11c, 11e, 11g, and 11s exhibited favorable inhibitory effects on IDH1/R132H and were highly selective against the wild-type IDH1. Evaluation of the biological activities at the cellular level showed that compounds 11a, 11c, 11e, 11g, and 11s could effectively suppress the production of 2-hydroxyglutaric acid in U87MG cells expressing IDH1/R132H. Preliminary structure-activity relationship (SAR) and molecular modeling studies were discussed based on the experimental data obtained. These findings may provide new insights into the development of novel IDH1/R132H inhibitors.

Beyond Brooding on Oncometabolic Havoc in IDH-Mutant Gliomas and AML: Current and Future Therapeutic Strategies

Isocitrate dehydrogenases 1 and 2 (IDH1,2), the key Krebs cycle enzymes that generate NADPH reducing equivalents, undergo heterozygous mutations in >70% of low- to mid-grade gliomas and ~20% of acute myeloid leukemias (AMLs) and gain an unusual new activity of reducing the α-ketoglutarate (α-KG) to D-2 hydroxyglutarate (D-2HG) in a NADPH-consuming reaction. The oncometabolite D-2HG, which accumulates >35 mM, is widely accepted to drive a progressive oncogenesis besides exacerbating the already increased oxidative stress in these cancers. More importantly, D-2HG competes with α-KG and inhibits a large number of α-KG-dependent dioxygenases such as TET (Ten-eleven translocation), JmjC domain-containing KDMs (histone lysine demethylases), and the ALKBH DNA repair proteins that ultimately lead to hypermethylation of the CpG islands in the genome. The resulting CpG Island Methylator Phenotype (CIMP) accounts for major gene expression changes including the silencing of the MGMT (O⁶-methylguanine DNA methyltransferase) repair protein in gliomas. Glioma patients with IDH1 mutations also show better therapeutic responses and longer survival, the reasons for which are yet unclear. There has been a great surge in drug discovery for curtailing the mutant IDH activities, and arresting tumor proliferation; however, given the unique and chronic metabolic effects of D-2HG, the promise of these compounds for glioma treatment is uncertain. This comprehensive review discusses the biology, current drug design and opportunities for improved therapies through exploitable synthetic lethality pathways, and an intriguing oncometabolite-inspired strategy for primary glioblastoma.

Inhibition of Glycolysis and Glutaminolysis: An Emerging Drug Discovery Approach to Combat Cancer

Cancer cells have a very different metabolism from that of normal cells from which they are derived. Their metabolism is elevated, which allows them to sustain higher proliferative rate and resist some cell death signals. This phenomenon, known as the "Warburg effect", has become the focus of intensive efforts in the discovery of new therapeutic targets and new cancer drugs. Both glycolysis and glutaminolysis pathways are enhanced in cancer cells. While glycolysis is enhanced to satisfy the increasing energy demand of cancer cells, glutaminolysis is enhanced to provide biosynthetic precursors for cancer cells. It was recently discovered that there is a tyrosine phosphorylation of a specific isoform of pyruvate kinase, the M2 isoform, that is preferentially expressed in all cancer cells, which results in the generation of pyruvate through a unique enzymatic mechanism that is uncoupled from ATP production. Pyruvate produced through this unique enzymatic mechanism is converted primarily into lactic acid, rather than acetyl-CoA for the synthesis of citrate, which would normally then enter the citric acid cycle. Inhibition of key enzymes in glycolysis and glutaminolysis pathways with small molecules has provided a novel but emerging area of cancer research and has been proven effective in slowing the proliferation of cancer cells, with several inhibitors being in clinical trials. This review paper will cover recent advances in the development of chemotherapeutic agents against several metabolic targets for cancer therapy, including glucose transporters, hexokinase, pyruvate kinase M2, glutaminase, and isocitrate dehydrogenase.

Design, synthesis and biological activity of 3-pyrazine-2-yl-oxazolidin-2-ones as novel, potent and selective inhibitors of mutant isocitrate dehydrogenase 1

Isocitrate dehydrogenases (IDHs) catalyze the oxidative decarboxylation of isocitrate to alpha-ketoglutarate (α-KG) generating carbon dioxide and NADPH/NADH. Evidence suggests that the specific mutations in IDH1 are critical to the growth and reproduction of some tumor cells such as gliomas and acute myeloid leukemia, emerging as an attractive antitumor target. In order to discovery potent new mutant IDH1 inhibitors, we designed, synthesized and evaluated a series of allosteric mIDH1 inhibitors harboring the scaffold of 3-pyrazine-2-yl-oxazolidin-2-ones. All tested compounds effectively suppress the D-2-hydroxyglutarate (D-2-HG) production in cells transfected with IDH1-R132H and IDH1-R132C mutations at 10 μM and 50 μM. Importantly, compound 3g owns the similar inhibitory activity to the positive agent NI-1 and shows no significant toxicity at the two concentrations. The parallel artificial membrane permeation assay of the blood-brain barrier (PAMPA-BBB) identified 3g with a good ability to penetrate the blood-brain barrier (BBB). These findings indicate that 3g deserves further optimization as a lead compound for the treatment of patients with IDH1 mutated brain cancers.

Isocitrate dehydrogenase (IDH) inhibition as treatment of myeloid malignancies: Progress and future directions

Isocitrate dehydrogenase (IDH) is an essential metabolic enzyme. Over the last two decades, there has been a growing focus on the metabolic derangements that occur with IDH1 and IDH2 mutations. The altered IDH protein leads to accumulation of 2-hydroxyglutarate (2-HG), a metabolite with oncogenic activity via epigenetic mechanisms. The advent of IDH inhibitors has engendered hope in novel and targeted therapies in IDH1/2 mutant myeloid malignancies. We here summarize the basic physiology of IDH, the metabolic and oncogenic consequences of mutant IDH1/2, and the clinical significance of IDH inhibition in hematologic malignancies. We also discuss completed and ongoing clinical trials focusing on the inhibition of IDH proteins, which have demonstrated preliminary indications of efficacy. The promise of IDH inhibition is now being further investigated as a novel therapeutic approach for AML and other myeloid malignancies.