ABSTRACT
Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in the cells of individuals with AML. Our study provides proof of concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.
Subject(s)
Dihydropyridines/pharmacology , Enzyme Inhibitors/pharmacology , Isocitrate Dehydrogenase/antagonists & inhibitors , Leukemia, Myeloid, Acute/drug therapy , Pyrazoles/pharmacology , Allosteric Regulation , Allosteric Site , Animals , Cell Differentiation/drug effects , Cell Line, Tumor , CpG Islands , Crystallography, X-Ray , Cytosine/chemistry , Cytosine/metabolism , DNA Methylation/drug effects , Dihydropyridines/chemistry , Dihydropyridines/pharmacokinetics , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacokinetics , Granulocytes/drug effects , Granulocytes/enzymology , Granulocytes/pathology , Humans , Isocitrate Dehydrogenase/chemistry , Isocitrate Dehydrogenase/genetics , Isocitrate Dehydrogenase/metabolism , Kinetics , Leukemia, Myeloid, Acute/enzymology , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/pathology , Male , Mice , Models, Molecular , Mutation , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/enzymology , Neoplastic Stem Cells/pathology , Primary Cell Culture , Protein Binding , Pyrazoles/chemistry , Pyrazoles/pharmacokinetics , Xenograft Model Antitumor AssaysABSTRACT
Optimization of a benzimidazolone template for potency and physical properties revealed 5-aryl-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones as a key template on which to develop a new series of mGlu2 positive allosteric modulators (PAMs). Systematic investigation of aryl-SAR led to the identification of compound 27 as a potent and highly selective mGlu2 PAM with sufficient pharmacokinetics to advance to preclinical models of psychosis. Gratifyingly, compound 27 showed full efficacy in the PCP- and MK-801-induced hyperlocomotion assay in rats at CSF concentrations consistent with mGlu2 PAM potency.