ABSTRACT
Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are frequently found in several human cancer types including acute myeloid leukemia (AML) and lead to the production of high levels of the oncometabolite (R)-2-hydroxyglutarate (R-2HG). Here we report the characterization of BAY1436032, a novel pan-mutant IDH1 inhibitor, both in vitro and in vivo. BAY1436032 specifically inhibits R-2HG production and colony growth, and induces myeloid differentiation of AML cells carrying IDH1R132H, IDH1R132C, IDH1R132G, IDH1R132L and IDH1R132S mutations. In addition, the compound impacts on DNA methylation and attenuates histone hypermethylation. Oral administration of BAY1436032 led to leukemic blast clearance, myeloid differentiation, depletion of leukemic stem cells and prolonged survival in two independent patient-derived xenograft IDH1 mutant AML mouse models. Together, BAY1436032 is highly effective against all major types of IDH1 mutant AML.
Subject(s)
Aniline Compounds/therapeutic use , Antineoplastic Agents/therapeutic use , Benzimidazoles/therapeutic use , Enzyme Inhibitors/therapeutic use , Isocitrate Dehydrogenase/antagonists & inhibitors , Leukemia, Myeloid, Acute/drug therapy , Neoplasm Proteins/antagonists & inhibitors , Aniline Compounds/pharmacology , Animals , Antineoplastic Agents/pharmacology , Benzimidazoles/pharmacology , Cell Line, Tumor , DNA Methylation/drug effects , Enzyme Inhibitors/pharmacology , Glutarates/metabolism , Histone Code/drug effects , Humans , Isocitrate Dehydrogenase/genetics , Leukemia, Myeloid, Acute/enzymology , Leukemia, Myeloid, Acute/genetics , Methylation/drug effects , Mice , Molecular Targeted Therapy , Mutation , Mutation, Missense , Myeloid Cells/drug effects , Myelopoiesis/drug effects , Neoplasm Proteins/genetics , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/enzymology , Point Mutation , Protein Processing, Post-Translational/drug effects , Tumor Stem Cell Assay , Xenograft Model Antitumor AssaysABSTRACT
Canonical mutations in IDH1 and IDH2 produce high levels of the R-enantiomer of 2-hydroxyglutarate (R-2HG), which is a competitive inhibitor of α-ketoglutarate (αKG)-dependent enzymes and a putative oncometabolite. Mutant IDH1 collaborates with HoxA9 to induce monocytic leukemia in vivo. We used two mouse models and a patient-derived acute myeloid leukemia xenotransplantation (PDX) model to evaluate the in vivo transforming potential of R-2HG, S-2HG and αKG independent of the mutant IDH1 protein. We show that R-2HG, but not S-2HG or αKG, is an oncometabolite in vivo that does not require the mutant IDH1 protein to induce hyperleukocytosis and to accelerate the onset of murine and human leukemia. Thus, circulating R-2HG acts in a paracrine manner and can drive the expansion of many different leukemic and preleukemic clones that may express wild-type IDH1, and therefore can be a driver of clonal evolution and diversity. In addition, we show that the mutant IDH1 protein is a stronger oncogene than R-2HG alone when comparable intracellular R-2HG levels are achieved. We therefore propose R-2HG-independent oncogenic functions of mutant IDH1 that may need to be targeted in addition to R-2HG production to exploit the full therapeutic potential of IDH1 inhibition.
