Somatic mutations in the isocitrate dehydrogenase (IDH) enzymes contribute to the pathogenesis of acute myeloid leukemia (AML) and other malignancies via production of the `oncometabolite' D-2-hydroxyglutarate (D-2HG). D-2HG blocks differentiation of malignant cells by inhibiting ?-ketoglutarate (?KG)-dependent enzymes that regulate chromatin structure and gene expression. Small molecule inhibitors of mutant IDH enzymes are emerging as promising new therapies for patients with AML, but their efficacy remains limited to the subset of patients with IDH mutations. 2HG is a chiral molecule that can exist in either the D- or L- enantiomer. Biochemical assays show that L-2HG functions much more potently than D-2HG as an inhibitor of ?KG-dependent chromatin-modifying enzymes, but biological sources and activities of L-2HG are poorly understood. Preliminary data presented in this proposal describe a previously unknown metabolic pathway where under conditions of oxygen limitation (a.k.a. hypoxia), cells potently and selectively produce L-2HG via promiscuous enzymatic reduction of ?KG by lactate dehydrogenase. L-2HG stabilizes hypoxia-inducible factor 1? (HIF1?) and increases repressive histone modifications characteristic of the undifferentiated/stem cell state. The hypoxia-induced L-2HG pathway is active in primary embryonic and hematopoietic stem cells (ESCs/HSCs) and leukemia cells, and experimental manipulations that increase L-2HG levels block the differentiation of primary HSCs and ESCs. Normal blood stem cells and leukemia cells reside in and depend on hypoxic regions of the bone marrow. Thus, L-2HG might represent a molecular mechanism whereby hypoxic niches promote and maintain the immature state of normal blood stem cells and leukemia stem/progenitor cells. This hypothesis will be rigorously tested by (1) using in vitro systems to elucidate the effects of L-2HG on hematopoietic cell gene expression, epigenetic modifications, and differentiation, (2) employing in vivo mouse models to determine if L-2HG influences normal or malignant hematopoiesis, and (3) utilizing patient samples to determine if deregulated L-2HG metabolism is a feature of human leukemia. The proposed investigations will expand the armamentarium of strategies to therapeutically target 2HG in cancer, particularly for the large cohort of patients who lack IDH mutations. The applicant, Dr. Andrew Intlekofer, an Assistant Attending with the Lymphoma Service at Memorial Sloan Kettering Cancer Center (MSKCC), has outlined a 5-year career plan that builds upon his research background studying molecular mechanisms of cell differentiation and his clinical training in oncology and malignant hematology. Dr. Intlekofer will conduct the proposed research under the mentorship of Dr. Craig Thompson, an internationally recognized expert in cancer metabolism with a strong track record of training successful physician scientists. MSKCC provides the ideal institutional environment for Dr. Intlekofer to embark on the proposed research program and transition to a position as an independent academic investigator with his own laboratory and R01 funding.

Public Health Relevance

New drugs that target metabolic pathways have shown promise for the treatment of cancer, but the benefits of these drugs have been restricted to rare patients whose cancers have mutations in metabolic enzymes. We have identified a new metabolic pathway whereby normal stem cells and almost all cancer cells produce a metabolite called L-2-hydroxyglutarate (L-2HG) that regulates key aspects of cell identity and function. The proposed research will test the importance of L-2HG in normal stem blood stem cells and leukemia cells to determine how L-2HG affects cells and whether targeting the L-2HG pathway represents a useful and broadly applicable strategy for treating cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Clinical Investigator Award (CIA) (K08)
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Subcommittee I - Transistion to Independence (NCI)
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Lim, Susan E
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Sloan-Kettering Institute for Cancer Research
New York
United States
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Intlekofer, Andrew M; Joffe, Erel; Batlevi, Connie L et al. (2018) Integrated DNA/RNA targeted genomic profiling of diffuse large B-cell lymphoma using a clinical assay. Blood Cancer J 8:60
Harding, James J; Lowery, Maeve A; Shih, Alan H et al. (2018) Isoform Switching as a Mechanism of Acquired Resistance to Mutant Isocitrate Dehydrogenase Inhibition. Cancer Discov 8:1540-1547
Intlekofer, Andrew M; Shih, Alan H; Wang, Bo et al. (2018) Acquired resistance to IDH inhibition through trans or cis dimer-interface mutations. Nature 559:125-129
Intlekofer, Andrew M; Wang, Bo; Liu, Hui et al. (2017) L-2-Hydroxyglutarate production arises from noncanonical enzyme function at acidic pH. Nat Chem Biol 13:494-500