Abstract 1875: Oxidative metabolism as a novel therapeutic target to eradicate T-ALL with mitochondrial complex I inhibitor IACS-010759
Authors: Baran Natalia , Lodi Alessia , Sweeney Shannon , Kuruvilla Vinitha Mary , Cavazos Antonio , Skwarska Anna , Velandy Sriram Shanmuga , Harutyunyan Karine , Feng Ningping , Gay Jason , Kaminski Marcin , Jabbour Elias J. , Ferrando Adolfo , Francesco M. Emilia Di , Marszalek Joseph R. , Tiziani Stefano , Konopleva Marina 
Published: August 2018

Abstract
Adult T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy with limited treatment options, largely driven by the activating Notch1 mutations. Oncogenic Notch1 facilitates c-Myc signaling and glutamine oxidation, induces metabolic stress and increased reliance on oxidative metabolism maintained by AMPK and modulates metabolism under energy stress by mTOR (Kishton, Cell Metabolism 2016; Chan, Blood 2007).
In this study, we report pre-clinical activity of the novel OXPHOS inhibitor (OXPHOSi) IACS-010759 in NOTCH-mutated T-ALL, and characterize the cellular and metabolic responses to OxPhos inhibition. Exposure to IACS-010759 (0-370 nM) in vitro for 5 days drastically reduced T-ALL viability, with EC50 ranging from 0.001-10 nM for T-ALL cell lines and 13-45 nM for T-ALL PDX models (n=5). Oral administration of IACS-010759 at 7.5 mg/kg daily was tolerable in both, aggressive T-ALL PDX and in Notch-1 mutated murine T-ALL model, significantly reduced leukemia burden and extended survival. Functional metabolic characterization of T-ALL confirmed that IACS-010759 effectively inhibited mitochondrial respiration and caused striking dose-dependent decrease in basal and maximal OCR, ATP and NADH production. Pharmacological inhibition of Complex I with IACS-010759, similar to knockout of Complex I subunit NDUSF4 using CRISPR-CAS9, induced catastrophic changes in mitochondria, with induction of ROS, DNA damage and compensatory mTOR pathway activation. Further, OXPHOSi led to downregulation of mitochondrial Complex I, II, III and IV, decrease of wide range of TCA cycle enzymes and proteins involved in the mitochondrial transport. This translated into decrease of TCA cycle intermediates and reduction in ATP and NADH content by metabolomic analysis. Using stable isotope-resolved metabolomics (SIRM) flux analysis, IACS-010759 (30 nM at 24 hr) significantly decreased flux of glucose through the TCA cycle and redirected it towards glycolysis, additionally increased utilization of glutamine for fueling the TCA cycle, in particular through reductive metabolism, uncovering reliance on glutaminolysis as an additional therapeutic target. Consistent with this hypothesis, combined therapy of OXPHOSi with Glutaminase (GLS-i) or mTOR inhibitors caused additive or synergistic reduction of viability of T-ALL cells, and elicited anti-leukemia activity in T-ALL resistant to Complex I inhibitor alone. Ongoing in vivo studies will address the impact of Complex I Inhibition in the context of genetic GLS knockout utilizing Notch1-mutated GLS fl/fl murine model (Herranz, Nat Med 2016). Taken together, our findings indicate that OXPHOSi, alone and more so in combination with GLS inhibition, constitutes an novel therapeutic modality that targets unique metabolic vulnerability of Notch1- mutated T-ALL cells.
Citation Format: Natalia Baran, Alessia Lodi, Shannon Sweeney, Vinitha Mary Kuruvilla, Antonio Cavazos, Anna Skwarska, Sriram Shanmuga Velandy, Karine Harutyunyan, Ningping Feng, Jason Gay, Marcin Kaminski, Elias J. Jabbour, Adolfo Ferrando, M. Emilia Di Francesco, Joseph R. Marszalek, Stefano Tiziani, Marina Konopleva. Oxidative metabolism as a novel therapeutic target to eradicate T-ALL with mitochondrial complex I inhibitor IACS-010759 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1875.