Metabolic reprograming is an emerging hallmark of tumor biology and an actively pursued opportunity in discovery of oncology drugs. Extensive efforts have focused on therapeutic targeting of glycolysis, whereas drugging mitochondrial oxidative phosphorylation (OXPHOS) has remained largely unexplored, partly owing to an incomplete understanding of tumor contexts in which OXPHOS is essential. Here, we report the discovery of IACS-010759, a clinical-grade small-molecule inhibitor of complex I of the mitochondrial electron transport chain. Treatment with IACS-010759 robustly inhibited proliferation and induced apoptosis in models of brain cancer and acute myeloid leukemia (AML) reliant on OXPHOS, likely owing to a combination of energy depletion and reduced aspartate production that leads to impaired nucleotide biosynthesis. In models of brain cancer and AML, tumor growth was potently inhibited in vivo following IACS-010759 treatment at well-tolerated doses. IACS-010759 is currently being evaluated in phase 1 clinical trials in relapsed/refractory AML and solid tumors.

TWEAK is a member of the TNF ligand family that induces angiogenesis in vivo. We report cloning of a receptor for TWEAK (TweakR) from a human umbilical vein endothelial cell (HUVEC) library. The mature form of TweakR has only one hundred and two amino acids and six cysteine residues in its extracellular region. Five different assays demonstrate TWEAK-TweakR binding, and the interaction affinity constant (Kd) is within a physiologically relevant range of 2.3 +/- 0.1 nM. The TweakR cytoplasmic domain binds TRAFs 1, 2, and 3. Cross-linking of TweakR induces HUVEC growth, and mRNA levels are upregulated in vitro by a variety of agents and in vivo following arterial injury. Soluble TweakR inhibits endothelial cell migration in vitro and corneal angiogenesis in vivo.

Highlights d PGD is a top hit in a loss-of-function genetics screen in OXPHOS-deficient cancer d OXPHOS-deficient cells depend on PGD in vitro and in vivo d PGD inhibition affects glycolysis, reductive carboxylation, and redox homeostasis d Pharmacological inhibition of OXPHOS renders PGD dependent

Tumor cells normally depend on both glycolysis and oxidative phosphorylation (OXPHOS) to provide the energy and macromolecule building blocks needed to enable continued tumor cell growth. Genetic or epigenetic inactivation of one of these two redundant pathways represents a metabolic vulnerability that should be susceptible to an inhibitor of the other pathway. Through an extensive medicinal chemistry campaign, IACS-10759 was identified as a potent inhibitor of complex I of oxidative phosphorylation. In isolated mitochondria or permeabilized cells, ATP production or oxygen consumption was inhibited at single digit nM concentrations in the presence of malate/glutamate, but not succinate. More directly, IACS-10759 inhibited the conversion of NADH to NAD+ in an immunoprecipitated complex I assay at low nM concentrations. Using genetic and pharmacological approaches, the specific complex I subunit inhibited by IACS-10759 has been identified and the mechanism of complex I inhibition is being investigated. Importantly, IACS-10759 is orally bioavailable with excellent physicochemical properties in preclinical species and achieved significant in vivo efficacy with daily oral dosing of 10-25 mg/kg. Specifically, there was a >50 day extension of median survival in an orthotopic AML cell line xenograft and robust regression in DLBCL and GBM xenograft models. In light of these results, as well as its drug like profile IACS-10759 has entered IND enabling studies with first-in-human studies targeted for third quarter of 2015. Citation Format: Marina Protopopova, Madhavi Bandi, Jennifer Bardenhagen, Christopher Bristow, Christopher Carroll, Edward Chang, Ningping Feng, Jason Gay, Mary Geck Do, Jennifer Greer, Marina Konopleva, Polina Matre, Zhijun Kang, Gang Liu, Florian Muller, Timothy Lofton, Timothy McAfoos, Yuting Sun, Melinda Smith, Jay Theroff, Yuanqiang Wu, Lynda Chin, Giulio Draetta, Philip Jones, Carlo Toniatti, M. Emilia Di Francesco, Joseph R. Marszalek. IACS-10759: A novel OXPHOS inhibitor which selectively kill tumors with metabolic vulnerabilities. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4380. doi:10.1158/1538-7445.AM2015-4380

Tumor cells normally depend on both glycolysis and oxidative phosphorylation (OXPHOS) to provide the energy and macromolecule building blocks for rapid growth. Metabolic vulnerabilities caused by inactivation of glycolysis render tumor cells highly dependent on OXPHOS, and represent a therapeutic opportunity. Through an extensive medicinal chemistry campaign, we have identified IACS-10759 as a potent inhibitor of complex I of OXPHOS. IACS-10759 effectively inhibits ATP production and oxygen consumption in isolated mitochondria, and inhibits the conversion of NADH to NAD+ in immunoprecipitated complex I in low nM range. The exact subunit that IACS-10759 binds to is under investigation. Importantly, IACS-10759 is orally bioavailable with excellent physicochemical properties in preclinical species, and shows significant efficacy in multiple tumor indications both in vitro and in vivo. Specifically, in a glycolysis-deficient xenograft model, IACS-10759 causes robust tumor regression, but has no effect in the same model when glycolysis is restored. In addition, in AML where tumor cells have been shown to be highly OXPHOS-dependent, IACS-10759 robustly suppresses cell growth and induces apoptosis in both primary AML samples and cell lines in vitro, but not in normal patient-derived bone marrow cells. Significantly, IACS-10759 extends median survival by over 50 days in an AML orthotopic xenograft model. Furthermore, IACS-10759 also shows selective efficacy in other cell line panels including pancreatic cancer, non-small cell lung cancer and colorectal cancer, and has synergism with glycolysis inhibitors. In light of these results, we are currently performing IND enabling studies for IACS-10759, with first-in-human studies targeted for fourth quarter of 2015. Citation Format: Marina Protopopova, Madhavi Bandi, Yuting Sun, Jennifer Bardenhagen, Christopher Bristow, Christopher Carroll, Edward Chang, Ningping Feng, Jason Gay, Mary Geck Do, Jennifer Greer, Marina Konopleva, Polina Matre, Zhijun Kang, Gang Liu, Florian Muller, Timothy Lofton, Timothy McAfoos, Melinda Smith, Jay Theroff, Jing Han, Yuanqing Wu, Lynda Chin, Giulio Draetta, Philip Jones, Carlo Toniatti, M. Emilia Di Francesco, Joseph R. Marszalek. IACS-10759: A novel OXPHOS inhibitor that selectively kills tumors with metabolic vulnerabilities. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr A65.