agi-6780 and Leukemia--Myeloid--Acute

Mutations of IDH1 and IDH2, which produce the oncometabolite 2-hydroxyglutarate (2HG), have been identified in several tumors, including acute myeloid leukemia. Recent studies have shown that expression of the IDH mutant enzymes results in high levels of 2HG and a block in cellular differentiation that can be reversed with IDH mutant-specific small-molecule inhibitors. To further understand the role of IDH mutations in cancer, we conducted mechanistic studies in the TF-1 IDH2 R140Q erythroleukemia model system and found that IDH2 mutant expression caused both histone and genomic DNA methylation changes that can be reversed when IDH2 mutant activity is inhibited. Specifically, histone hypermethylation is rapidly reversed within days, whereas reversal of DNA hypermethylation proceeds in a progressive manner over the course of weeks. We identified several gene signatures implicated in tumorigenesis of leukemia and lymphoma, indicating a selective modulation of relevant cancer genes by IDH mutations. As methylation of DNA and histones is closely linked to mRNA expression and differentiation, these results indicate that IDH2 mutant inhibition may function as a cancer therapy via histone and DNA demethylation at genes involved in differentiation and tumorigenesis.

Topics: Cell Line, Tumor; Chromatin Immunoprecipitation; Chromatography, Liquid; DNA Methylation; Enzyme Inhibitors; Histones; Humans; Isocitrate Dehydrogenase; Leukemia, Myeloid, Acute; Mutation; Phenylurea Compounds; Principal Component Analysis; Reverse Transcriptase Polymerase Chain Reaction; Sulfonamides; Tandem Mass Spectrometry; Transcriptome

A number of human cancers harbor somatic point mutations in the genes encoding isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2). These mutations alter residues in the enzyme active sites and confer a gain-of-function in cancer cells, resulting in the accumulation and secretion of the oncometabolite (R)-2-hydroxyglutarate (2HG). We developed a small molecule, AGI-6780, that potently and selectively inhibits the tumor-associated mutant IDH2/R140Q. A crystal structure of AGI-6780 complexed with IDH2/R140Q revealed that the inhibitor binds in an allosteric manner at the dimer interface. The results of steady-state enzymology analysis were consistent with allostery and slow-tight binding by AGI-6780. Treatment with AGI-6780 induced differentiation of TF-1 erythroleukemia and primary human acute myelogenous leukemia cells in vitro. These data provide proof-of-concept that inhibitors targeting mutant IDH2/R140Q could have potential applications as a differentiation therapy for cancer.

Topics: Allosteric Site; Antineoplastic Agents; Catalytic Domain; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Crystallography, X-Ray; Enzyme Inhibitors; Erythropoiesis; Gene Expression Regulation, Leukemic; Glutarates; Hematopoiesis; Humans; Isocitrate Dehydrogenase; Leukemia, Erythroblastic, Acute; Leukemia, Myeloid, Acute; Molecular Targeted Therapy; Mutant Proteins; Phenylurea Compounds; Point Mutation; Protein Multimerization; Protein Structure, Secondary; Small Molecule Libraries; Sulfonamides

Topics: Animals; Benzeneacetamides; Cell Differentiation; Cell Transformation, Neoplastic; Enzyme Inhibitors; Glioma; Glutarates; Hematopoiesis; Humans; Imidazoles; Isocitrate Dehydrogenase; Leukemia; Leukemia, Myeloid, Acute; Phenylurea Compounds; Procollagen-Proline Dioxygenase; Sulfonamides