glutaminase and Leukemia--Myeloid--Acute

Topics: Animals; Carbon-Nitrogen Ligases; DNA-Binding Proteins; Gene Expression Regulation, Enzymologic; Glutaminase; Histone-Lysine N-Methyltransferase; Humans; Leukemia, Myeloid, Acute; Myeloid-Lymphoid Leukemia Protein; Protein Conformation; Protein Structure, Tertiary; Proto-Oncogenes; Purine Nucleotides; Pyrophosphatases; Transcription Factors

We treated 13 adult patients with acute leukemia or chronic myelocytic leukemia (CML) in blast phase using succinylated Acinetobacter glutaminase-asparaginase (SAGA) administered on a daily dose schedule. SAGA reduced the peripheral blast count in two patients with acute lymphoblastic leukemia and two with blastic CML; however, no patient achieved either complete or partial remission. Marked central nervous system toxic effects (encephalopathy and coma) were observed, limiting treatment in patients whose disease appeared responsive; this effect finally prompted early discontinuance of the trial. Other toxic effects observed included nausea, hyperglycemia, and respiratory alkalosis. Hypersensitivity reactions to the enzyme were not seen. Pharmacologic analyses showed that prolonged blood glutamine depletion was achieved only by daily enzyme administration; however, we noted the importance of performing amino acid analysis on blood which was deproteinized immediately following phlebotomy. Our results demonstrate excessive central nervous system toxicity when glutaminase-asparaginase is administered on a daily schedule. Because of this effect, we propose that future trials of similar enzymes be limited to short courses of enzyme therapy, possibly with the addition of antimetabolites or amino acid analogs, which could enhance the antitumor effect without increasing toxicity.

Topics: Acinetobacter; Adult; Antineoplastic Agents; Asparaginase; Clinical Trials as Topic; Drug Administration Schedule; Follow-Up Studies; Glutaminase; Humans; Leukemia; Leukemia, Lymphoid; Leukemia, Myeloid; Leukemia, Myeloid, Acute

A glutaminase-asparaginase enzyme from Achromobacter sp has antitumour activity in vitro and in animals. Glutaminase was administered in doses of 3500-20 000 IU/m2 body surface area/day to six patients with acute lymphoblastic leukaemia (ALL) and three patients with acute myeloid leukaemia (AML). The enzyme had a blood half life of 80 minutes but depletion of blood glutamine persisted for 12 hours after single doses. Seven patients, including four (two with AML and two with ALL) resistant to asparaginase, received repeated doses of glutaminase. Antileukaemic effects were observed in all seven; one elderly patient developed metabolic acidosis. Study of this new antileukaemic agent in patients with acute leukaemia at an earlier stage of their disease is now justified.

Topics: Acidosis; Adolescent; Adult; Aged; Alcaligenes; Asparagine; Child; Clinical Trials as Topic; Female; Glutaminase; Glutamine; Half-Life; Humans; Leukemia, Lymphoid; Leukemia, Myeloid, Acute; Male

Asparagine is a non-essential amino acid since it can either be taken up via the diet or synthesized by asparagine synthetase. Acute lymphoblastic leukemia (ALL) cells do not express asparagine synthetase or express it only minimally, which makes them completely dependent on extracellular asparagine for their growth and survival. This dependency makes ALL cells vulnerable to treatment with L-asparaginase, an enzyme that hydrolyzes asparagine. To date, all clinically approved L-asparaginases have significant L-glutaminase co-activity, associated with non-immune related toxic side effects observed during therapy. Therefore, reduction of L-glutaminase co-activity with concomitant maintenance of its anticancer L-asparaginase effect may effectively improve the tolerability of this unique drug. Previously, we designed a new alternative variant of Erwinia chrysanthemi (ErA; Erwinaze) with decreased L-glutaminase co-activity, while maintaining its L-asparaginase activity, by the introduction of three key mutations around the active site (ErA-TM). However, Erwinaze and our ErA-TM variant have very short half-lives in vivo. Here, we show that the fusion of ErA-TM with an albumin binding domain (ABD)-tag significantly increases its in vivo persistence. In addition, we evaluated the in vivo therapeutic efficacy of ABD-ErA-TM in a B-ALL xenograft model of SUP-B15. Our results show a comparable long-lasting durable antileukemic effect between the standard-of-care pegylated-asparaginase and ABD-ErA-TM L-asparaginase, but with fewer co-glutaminase-related acute side effects. Since the toxic side effects of current L-asparaginases often result in treatment discontinuation in ALL patients, this novel ErA-TM variant with ultra-low L-glutaminase co-activity and long in vivo persistence may have great clinical potential.

Topics: Asparaginase; Asparagine; Aspartate-Ammonia Ligase; Glutaminase; Humans; Leukemia, Myeloid, Acute; Precursor Cell Lymphoblastic Leukemia-Lymphoma

Acute myeloid leukemia (AML) is a blood cancer that is poorly responsive to conventional cytotoxic chemotherapy and a diagnosis of AML is usually fatal. More effective and better-tolerated therapies for AML are desperately needed. Activating mutations in FMS-like tyrosine kinase 3 (FLT3) are one of the most frequently observed genetic defects in AML. FLT3 inhibitors have shown impressive anti-leukemic activity in clinical trials; however, sustained remissions using these inhibitors as monotherapy have not been achieved. Our previous studies have implicated impaired glutamine metabolism in response to FLT3 inhibitors as a dominant factor causing AML cell death. In this study, we have employed metabolic flux analysis to examine the effects of FLT3 inhibition on glutamine utilization in FLT3-mutated AML cells using stable isotope tracers. We found that the FLT3 inhibitor AC220 inhibited glutamine flux into the antioxidant factor glutathione profoundly due to defective glutamine import. We also found that the glutaminase inhibitor CB-839 similarly impaired glutathione production by effectively blocking flux of glutamine into glutamate. Moreover, the combination of AC220 with CB-839 synergized to deplete glutathione, induce mitochondrial reactive oxygen species, and cause loss of viability through apoptotic cell death. In vivo, glutaminase inhibition with CB-839 facilitated leukemic cell elimination by AC220 and improved survival significantly in a patient-derived xenograft AML mouse model. Therefore, targeting glutaminase in combination with FLT3 may represent an effective therapeutic strategy for improving treatment of FLT3-mutated AML.

Topics: Animals; Benzeneacetamides; Benzothiazoles; Cell Line, Tumor; Female; fms-Like Tyrosine Kinase 3; Glutamic Acid; Glutaminase; Glutamine; Humans; Leukemia, Myeloid, Acute; Mice; Mice, Inbred NOD; Mice, Transgenic; Phenylurea Compounds; Thiadiazoles; Xenograft Model Antitumor Assays

Metabolic reprogramming has been described as a hallmark of transformed cancer cells. In this study, we examined the role of the glutamine (Gln) utilization pathway in acute myeloid leukemia (AML) cell lines and primary AML samples. Our results indicate that a subset of AML cell lines is sensitive to Gln deprivation. Glutaminase (GLS) is a mitochondrial enzyme that catalyzes the conversion of Gln to glutamate. One of the two GLS isoenzymes, GLS1 is highly expressed in cancer and encodes two different isoforms: kidney (KGA) and glutaminase C (GAC). We analyzed mRNA expression of GLS1 splicing variants, GAC and KGA, in several large AML datasets and identified increased levels of expression in AML patients with complex cytogenetics and within specific molecular subsets. Inhibition of glutaminase by allosteric GLS inhibitor bis-2-(5-phenylacetamido-1, 2, 4-thiadiazol-2-yl) ethyl sulfide or by novel, potent, orally bioavailable GLS inhibitor CB-839 reduced intracellular glutamate levels and inhibited growth of AML cells. In cell lines and patient samples harboring IDH1/IDH2 (Isocitrate dehydrogenase 1 and 2) mutations, CB-839 reduced production of oncometabolite 2-hydroxyglutarate, inducing differentiation. These findings indicate potential utility of glutaminase inhibitors in AML therapy, which can inhibit cell growth, induce apoptosis and/or differentiation in specific leukemia subtypes.

Topics: Antineoplastic Agents; Apoptosis; Benzeneacetamides; Cell Differentiation; Cell Proliferation; Energy Metabolism; Enzyme Inhibitors; Glutamate Dehydrogenase; Glutamic Acid; Glutaminase; Glutamine; Glutarates; Humans; Isocitrate Dehydrogenase; Leukemia, Myeloid, Acute; Mutation; Protein Isoforms; Sulfides; Thiadiazoles

Cancer cells require glutamine to adapt to increased biosynthetic activity. The limiting step in intracellular glutamine catabolism involves its conversion to glutamate by glutaminase (GA). Different GA isoforms are encoded by the genes GLS1 and GLS2 in humans. Herein, we show that glutamine levels control mitochondrial oxidative phosphorylation (OXPHOS) in acute myeloid leukemia (AML) cells. Glutaminase C (GAC) is the GA isoform that is most abundantly expressed in AML. Both knockdown of GLS1 expression and pharmacologic GLS1 inhibition by the drug CB-839 can reduce OXPHOS, leading to leukemic cell proliferation arrest and apoptosis without causing cytotoxic activity against normal human CD34(+) progenitors. Strikingly, GLS1 knockdown dramatically inhibited AML development in NSG mice. The antileukemic activity of CB-839 was abrogated by both the expression of a hyperactive GAC(K320A) allele and the addition of the tricarboxyclic acid cycle product α-ketoglutarate, indicating the critical function of GLS1 in AML cell survival. Finally, glutaminolysis inhibition activated mitochondrial apoptosis and synergistically sensitized leukemic cells to priming with the BCL-2 inhibitor ABT-199. These findings show that targeting glutamine addiction via GLS1 inhibition offers a potential novel therapeutic strategy for AML.

Topics: Animals; Antineoplastic Agents; Apoptosis; Benzeneacetamides; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Cell Proliferation; Citric Acid Cycle; Enzyme Inhibitors; Gene Knockdown Techniques; Glutaminase; Glutamine; Humans; Leukemia, Myeloid, Acute; Mice; Mitochondria; Oxidative Phosphorylation; Oxygen Consumption; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Thiadiazoles; Xenograft Model Antitumor Assays

The incidence of mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) in de novo acute myeloid leukemia (AML) is approximately 20%. These mutations result in distinct metabolic characteristics including dependency of cancer cells on glutamine as the main source for α-ketoglutarate, which is consumed by leukemia cells to produce a cancer-derived metabolite, 2-hydroxyglutarate. We sought to exploit this glutamine addiction therapeutically in mutant IDH primary AML cells from patients by measuring cell growth after exposure to a small molecule glutaminase inhibitor, BPTES. We found that BPTES only suppressed the growth of AML cells expressing mutant IDH compared with those expressing wild type IDH. This study lays the groundwork for strategies to target a specific subtype of AML metabolically with IDH mutations with a unique reprogramming of intermediary metabolism that culminates in glutamine dependency of cancer cells for survival.

Topics: Cell Line, Tumor; Cell Survival; Female; Glutaminase; Humans; Isocitrate Dehydrogenase; Leukemia, Myeloid, Acute; Male; Mutation; Sulfides; Thiadiazoles

Cancer cells require nutrients and energy to adapt to increased biosynthetic activity, and protein synthesis inhibition downstream of mammalian target of rapamycin complex 1 (mTORC1) has shown promise as a possible therapy for acute myeloid leukemia (AML). Glutamine contributes to leucine import into cells, which controls the amino acid/Rag/mTORC1 signaling pathway. We show in our current study that glutamine removal inhibits mTORC1 and induces apoptosis in AML cells. The knockdown of the SLC1A5 high-affinity transporter for glutamine induces apoptosis and inhibits tumor formation in a mouse AML xenotransplantation model. l-asparaginase (l-ase) is an anticancer agent also harboring glutaminase activity. We show that l-ases from both Escherichia coli and Erwinia chrysanthemi profoundly inhibit mTORC1 and protein synthesis and that this inhibition correlates with their glutaminase activity levels and produces a strong apoptotic response in primary AML cells. We further show that l-ases upregulate glutamine synthase (GS) expression in leukemic cells and that a GS knockdown enhances l-ase-induced apoptosis in some AML cells. Finally, we observe a strong autophagic process upon l-ase treatment. These results suggest that l-ase anticancer activity and glutamine uptake inhibition are promising new therapeutic strategies for AML.

Topics: Adult; Aged; Aged, 80 and over; Amino Acid Transport System ASC; Animals; Apoptosis; Asparaginase; Autophagy; Bacterial Proteins; Biological Transport; Cell Line, Tumor; Dickeya chrysanthemi; Drug Screening Assays, Antitumor; Escherichia coli Proteins; Female; Glutaminase; Glutamine; Humans; Leukemia, Myeloid, Acute; Leukemia, Myelomonocytic, Acute; Male; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Nude; Middle Aged; Minor Histocompatibility Antigens; Multiprotein Complexes; Protein Biosynthesis; RNA Interference; RNA, Small Interfering; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays; Young Adult

Topics: Acinetobacter; Animals; Asparaginase; Disease Models, Animal; Glutaminase; Leukemia, Experimental; Leukemia, Myeloid, Acute; Neoplasm Transplantation; Rats; Rats, Inbred BN; Transplantation, Homologous