Christopher Carroll

Chemogenetic Evaluation of the Mitotic Kinesin CENP-E Reveals a Critical Role in Triple-Negative Breast Cancer

Breast cancer patients with tumors lacking the three diagnostic markers (ER, PR, and HER2) are classified as triple-negative (primarily basal-like) and have poor prognosis because there is no disease-specific therapy available. To address this unmet medical need, gene expression analyses using more than a thousand breast cancer samples were conducted, which identified elevated centromere protein E (CENP-E) expression in the basal-a molecular subtype relative to other subtypes. CENP-E, a mitotic kinesin component of the spindle assembly checkpoint, is shown to be induced in basal-a tumor cell lines by the mitotic spindle inhibitor drug docetaxel. CENP-E knockdown by inducible shRNA reduces basal-a breast cancer cell viability. A potent, selective CENP-E inhibitor (PF-2771) was used to define the contribution of CENP-E motor function to basal-like breast cancer. Mechanistic evaluation of PF-2771 in basal-a tumor cells links CENP-E–dependent molecular events (e.g., phosphorylation of histone H3 Ser-10; phospho-HH3-Ser10) to functional outcomes (e.g., chromosomal congression defects). Across a diverse panel of breast cell lines, CENP-E inhibition by PF-2771 selectively inhibits proliferation of basal breast cancer cell lines relative to premalignant ones and its response correlates with the degree of chromosomal instability. Pharmacokinetic–pharmacodynamic efficacy analysis in a basal-a xenograft tumor model shows that PF-2771 exposure is well correlated with increased phospho-HH3-Ser10 levels and tumor growth regression. Complete tumor regression is observed in a patient-derived, basal-a breast cancer xenograft tumor model treated with PF-2771. Tumor regression is also observed with PF-2771 in a taxane-resistant basal-a model. Taken together, CENP-E may be an effective therapeutic target for patients with triple-negative/basal-a breast cancer. Mol Cancer Ther; 13(8); 2104–15. ©2014 AACR.

An inhibitor of oxidative phosphorylation exploits cancer vulnerability

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.A new inhibitor targeting the mitochondrial complex I shows antitumor activity in preclinical models of acute myeloid leukemia and glioblastoma relying on oxidative phosphorylation.

Abstract A65: IACS-10759: A novel OXPHOS inhibitor that selectively kills tumors with metabolic vulnerabilities

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.

Abstract PR01: IACS-010759 a novel inhibitor of oxidative phosphorylation advancing into first-in-human studies to exploit metabolic vulnerabilities

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. We have identified multiple contexts where all or a subset of these tumors demonstrate a dependence on mitochondrial OXPHOS, which represents an exciting therapeutic opportunity. 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 is inhibited at single digit nM concentrations in the presence of malate/glutamate, but not succinate. More directly, IACS-10759 inhibits the conversion of NADH to NAD+ in an immunoprecipitated complex I assay at low nM concentrations. Importantly, IACS-10759 is orally bioavailable with excellent pharmacokinetics properties in preclinical species, and has an overall profile suitable for clinical development. Our group and others have demonstrated that a variety of tumor types including: AML, plus subsets of lymphoma, breast, melanoma and PDAC are highly dependent on OXPHOS to meet energy and biomass demands. Treatment of multiple cell lines and patient derived xenograft (PDX) models in multiple cancer types with IACS-10759 led to decreased oxygen consumption rate (OCR). IACS-10759 treatment also led to a robust decrease in cell viability and often an increase in apoptosis with EC50 values between 1 nM - 50 nM across multiple lines. In multiple PDX models of primary AML IACS-10759 treatment extends the median survival. Efficacy was paralleled by robust modulation of OCR, aspartate, and p-AMPK levels. Additionally, tumor growth inhibition or regression was also observed in cell line and PDX xenograft models of lymphoma, triple negative breast, melanoma and PDAC treated with IACS-10759, indicating that subsets of several non-AML indications are also dependent on OXPHOS. Mechanistically, extensive metabolic profiling revealed that the response to IACS-10759 was associated with induction of a metabolic imbalances that negatively impacted energy homeostasis, amino acid biosynthesis, and NTP production due to reduced conversion of NADH to NAD+ by complex I, decreased ATP production, TCA cycle flux and nucleotide biosynthesis. As a result of the robust preclinical response in multiple model systems, IACS-10759 has been advanced through IND enabling studies. GLP safety and toxicology have been completed, clinical supplies manufactured, and a Phase I clinical trial in AML will be initiated during the second quarter of 2016. This abstract is also being presented as Poster B35. Citation Format: Philip Jones, M Emilia Di Francesco, Jennifer M. Molina, Marina Protopopova, Madhavi Bandi, Jennifer Bardenhagen, Christopher A. Bristow, Christopher L. Carroll, Ningping Feng, Jason P. Gay, Mary K. Geck Do, Jennifer M. Greer, Marina Konopleva, Zhijun Kang, Gang Liu, Timothy McAfoos, Pietro Morlacchi, Melinda G. Smith, Sonal Fnu, Jay P. Theroff, Giulio Draetta, Giulio Draetta, Carlo Toniatti, Joseph R. Marszalek. IACS-010759 a novel inhibitor of oxidative phosphorylation advancing into first-in-human studies to exploit metabolic vulnerabilities. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Targeting the Vulnerabilities of Cancer; May 16-19, 2016; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(1_Suppl):Abstract nr PR01.

Abstract LB-A15: IACS-010759 is a novel inhibitor of oxidative phosphorylation that selectively targets AML cells by inducing a metabolic catastrophe

Acute myeloid leukemia (AML) is a highly aggressive disease with a high mortality rate that encompasses several genetically and clinically diverse hematological malignancies characterized by clonal expansion of transformed stem/progenitor cells with limited ability to differentiate into mature blood cells. Standard of care for AML has progressed minimally in the past 30 years for relapse/refractory AML, with survival rates of 65 years. Therefore, novel, highly effective therapeutics are needed for this population. Targeting bioenergetic susceptibilities is an exciting area of oncology therapeutics that is potentially applicable in AML. Our group and others have shown that AML blasts depend significantly on mitochondrial oxidative phosphorylation to meet their energy and biomass production demands. Through an extensive medicinal chemistry campaign IACS-10759 was identified as a potent, selective inhibitor of complex I of the electron transport chain with excellent PK and a suitable overall profile. In AML cell lines and primary AML blasts treated ex vivo, we observe a robust decrease in proliferation and a concomitant increase in apoptosis with EC50 values of less than 10 nM. Response to IACS-10759 in AML cells was associated with induction of a metabolic catastrophe that negatively impacted the cells9 ability to sustain energy homeostasis, amino acid biosynthesis, and nucleotide production. In a primary AML patient derived xenograft model from a patient who was refractory to standard of care and salvage therapies, 42 days of IACS-10759 (QDx5/week) treatment at 10 mg/kg extended the median survival by greater than 2-fold. Inhibition of OXPHOS by IACS-10759 was confirmed in AML cell lines and PDX models by a decrease in oxygen consumption and significant changes in gene and protein expression, non-essential amino acids and nucleotides. Due to the robust response in AML cell lines, primary AML samples ex vivo, and in vivo efficacy in primary AML PDX models, IACS-10759 has been advanced through IND enabling studies with first-in-human studies targeted for the second quarter of 2016. Citation Format: Jennifer R. Molina, Marina Protopopova, Madhavi Bandi, Jennifer Bardenhagen, Christopher Bristow, Maria Alimova, Christopher Carroll, Edward Chang, Ningping Feng, Jason Gay, Mary Geck Do, Jennifer Greer, Sha Huang, Yongying Jiang, Marina Konopleva, Polina Matre, Zhijun Kang, Gang Liu, Timothy McAfoos, Pietro Morlacchi, Melinda Smith, Sonal Sonal, Jay Theroff, Quanyun Xu, Giulio Draetta, Philip Jones, Carlo Toniatti, M. Emilia Di Francesco, Joseph R. Marszalek. IACS-010759 is a novel inhibitor of oxidative phosphorylation that selectively targets AML cells by inducing a metabolic catastrophe. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr LB-A15.

Abstract 4380: IACS-10759: A novel OXPHOS inhibitor which selectively kill tumors with metabolic vulnerabilities

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

Abstract 4971: IACS-010759, a novel inhibitor of complex I in Phase I clinical development to target OXPHOS dependent tumors

Tumor cells depend on both glycolysis and oxidative phosphorylation (OXPHOS) for energy and biomass production to support cell proliferation. Recent data has demonstrated a dependence of various tumor types on mitochondrial OXPHOS, which represents an exciting therapeutic opportunity. Through an extensive medicinal chemistry campaign, IACS-010759 was identified as a potent, selective inhibitor of complex I of the electron transport chain, which is orally bioavailable and has excellent PK and physicochemical properties in preclinical species. Our group and others have demonstrated that AML, plus subsets of glioblastoma, neuroblastoma, lymphoma, melanoma, triple negative breast cancer (TNBC) and pancreatic cancer (PDAC) are highly dependent on OXPHOS to meet energy and biomass demands. Treatment of multiple cell lines and patient derived xenograft (PDX) models in several cancer types with IACS-010759 led to a robust decrease in cell viability and often an increase in apoptosis with EC50 values between 1 nM - 50 nM across multiple lines. Through a series of mechanistic studies we established that IACS-10759 blocks complex I of the electron transport at the quinone binding site. Mechanistically, response to IACS-010759 was associated with induction of a metabolic imbalances that negatively impacted energy homeostasis, aspartate biosynthesis, and NTP production due to reduced conversion of NADH to NAD+ by complex I, decreased ATP production, TCA cycle flux and nucleotide biosynthesis. Tumor growth inhibition and regression have been observed in molecularly defined subsets of TNBC and PDAC PDX xenograft models treated with IACS-010759, indicating that subsets of these indications are dependent on OXPHOS. Furthermore, treating TNBC or PDAC PDX models post-chemotherapy with IACS-010759 extends progression free survival, consistent with IACS-010759 targeting recently described metabolically adapted residual tumor cells. In orthotopic xenograft models of primary AML cells, daily oral treatment with 1-7.5 mg/kg IACS-010759 extended the median survival. Efficacy was paralleled by robust modulation of OCR, aspartate, and a gene signature levels. Therefore, these readouts (OCR, aspartate and a nanostring geneset) have been validated for use as exploratory clinical biology of response endpoints. In parallel, completion of preclinical chemistry, manufacturing and control (CMC) as well as GLP safety and tolerability studies with IACS-010759 in multiple species have enabled the selection of a clinical entry dose. As a result of the robust response in multiple cell lines, primary patient samples, and efficacy in PDX models, a Phase I clinical trial in relapsed, refractory AML was initiated in October 2016, with a parallel trial in solid tumors expected to initiate in early 2017. Initial results from the on-going AML trial will be disclosed. Citation Format: Jennifer Molina, Madhavi Bandi, Jennifer Bardenhagen, Christopher Bristow, Christopher Carroll, Edward Chang, Jason Cross, Naval Daver, Ningping Feng, Jason Gay, Mary Geck Do, Jennifer Greer, Jing Han, Judy Hirst, Sha Huang, Yongying Jiang, Zhijun Kang, Marina Konopleva, Gang Liu, Helen Ma, Polina Matre, Timothy McAfoos, Funda Meric-Bernstam, Pietro Morlacchi, Florian Muller, Marina Protopopova, Melinda Smith, Sonal Sonal, Yuting Sun, Jay Theroff, Andrea Viale, Quanyun Xu, Carlo Toniatti, Giulio Draetta, Philip Jones, M. Emilia Di Francesco, Joseph R. Marszalek. IACS-010759, a novel inhibitor of complex I in Phase I clinical development to target OXPHOS dependent tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4971. doi:10.1158/1538-7445.AM2017-4971

Abstract 335: Title: IACS-010759 is a novel clinical candidate that targets AML cells by inducing a metabolic catastrophe through inhibition of oxidative phosphorylation

Tumor cells depend on both glycolysis and oxidative phosphorylation (OXPHOS) for energy and biomass production leading to robust cell proliferation. Recent data has demonstrated a dependence of various tumor types on mitochondrial OXPHOS, which represents an exciting therapeutic opportunity. Through an extensive medicinal chemistry campaign, IACS-10759 was identified as a potent, selective inhibitor of complex I of the electron transport chain, which is orally bioavailable and has excellent PK and physicochemical properties in preclinical species. Our group and others have demonstrated that a variety of tumor types including: AML, plus subsets of lymphoma, breast, melanoma and PDAC are highly dependent on OXPHOS to meet energy and biomass demands. Treatment of multiple cell lines and patient derived xenograft (PDX) models in multiple cancer types with IACS-10759 led to decreased oxygen consumption rate (OCR). IACS-10759 treatment also led to a robust decrease in cell viability and often an increase in apoptosis with EC50 values between 1 nM - 50 nM across multiple lines. Through a series of mechanistic studies we established that IACS-10759 blocks complex I of the electron transport at the quinone binding site. In an orthotopic xenograft model of primary AML cells derived from a patient who was refractory to standard of care and salvage therapies, 42 days of IACS-10759 treatment with 3 and 10 mg/kg orally using a 5 on/2 off schedule extended the median survival by greater than 2-fold. Efficacy was paralleled by robust modulation of OCR, aspartate, and p-AMPK levels. Additionally, tumor growth inhibition or regression was also observed in cell line and PDX xenograft models of lymphoma, triple negative breast, melanoma and PDAC treated with IACS-10759, indicating that subsets of several non-AML indications are also dependent on OXPHOS. Mechanistically, extensive metabolic profiling and flux analysis revealed that the response to IACS-10759 was associated with induction of a metabolic imbalance that negatively impacted energy homeostasis, amino acid biosynthesis, and NTP production due to reduced conversion of NADH to NAD+ by complex I, decreased ATP production, TCA cycle flux and nucleotide biosynthesis. As a result of the robust response in multiple cell lines, primary patient samples, and efficacy in PDX models, IACS-10759 has been advanced through IND enabling studies. GLP safety and toxicology have been completed, and we expect to file an IND at the end of 1Q2016 and initiate a Phase I clinical trial in AML during the second quarter of 2016. Citation Format: Jennifer R. Molina, Marina Protopopova, Madhavi Bandi, Jennifer Bardenhagen, Christopher Bristow, Christopher Carroll, Edward Chang, Ningping Feng, Jason Gay, Mary Geck Do, Jennifer Greer, Sha Huang, Yongying Jiang, Marina Konopleva, Polina Matre, Jing Han, Zhijun Kang, Gang Liu, Timothy McAfoos, Pietro Morlacchi, Melinda Smith, Sonal Gera, Jay Theroff, Quanyun Xu, Juliana Velez, Carlo Toniatti, Timothy Heffernan, Giulio Draetta, M. Emilia Di Francesco, Philip Jones, Joseph R. Marszalek. Title: IACS-010759 is a novel clinical candidate that targets AML cells by inducing a metabolic catastrophe through inhibition of oxidative phosphorylation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 335.

Abstract 4455: Relapsed/refractory AML responds robustly to IACS-10759, a novel OXPHOS inhibitor

Acute myeloid leukemia (AML) is a highly aggressive disease that is made up of several genetically and clinically diverse hematological malignancies that are characterized by clonal expansion of malignant stem/progenitor cells with limited ability to differentiate into mature blood cells. Standard of care for AML has progressed minimally in the past 30 years for relapse/refractory AML, with survival rates of 65 years. Therefore, novel, highly effective therapeutics are needed for this population. Growing evidence suggests that in AML, metabolism is altered and that the tumor cells become highly dependent of mitochondria oxidative phosphorylation (OXPHOS) for their survival. We developed IACS-10759 as a novel small molecule inhibitor of complex I that potently inhibits oxygen consumption, eliminates hypoxia, and strongly inhibits the proliferation of cells grown in galactose medium with EC50 values between 1-10 nM. When AML cell lines as well as primary AML cells from relapsed/refractory patients were treated ex vivo with IACS-10759, apoptosis was robustly induced with EC50 values also ranging between 1-10 nM. It is noteworthy, that while apoptosis was induced in primary AML cells, normal patient-derived bone marrow cells were not sensitive. In AML orthotopic xenografts, daily oral dosing with 15 mg/kg IACS-10759 extended median survival to 70 days from 18 days in control animals. Taken together, the robust response in AML cell lines, primary AML samples ex vivo, and efficacy in orthotopic xenografts, 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, Christophor 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, Jay Theroff, Yuting Sun, Yuanqiang Wu, Melinda Smith, Lynda Chin, Giulio Draetta, Philip Jones, Carlo Toniatti, M. Emilia Di Francesco, Joseph R. Marszalek. Relapsed/refractory AML responds robustly to IACS-10759, a novel OXPHOS inhibitor. [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 4455. doi:10.1158/1538-7445.AM2015-4455

Abstract 949: Identification of OXPHOS inhibitors which selectively kill tumors with specific metabolic vulnerabilities

Inhibition of mitochondria complex I in tumors that are metabolically dependent on oxidative phosphorylation (OXPHOS) for their survival offers unique synthetic lethal opportunities. Examples of dependent contexts are AML and DLBCL, where OXPHOS is highly active and subpopulations of glioblastoma and neuroblastoma that possess genetic alterations which make them glycolysis deficient. In addition, several lines of evidence indicate that after treatment with chemo or targeted therapy, residual tumor cells become reliant on OXPHOS for their continued survival. In each of these cellular states, excessive dependence on OXPHOS renders tumor cells vulnerable to therapeutic targeting strategies that exploit this addiction. We have generated a series of novel, highly potent complex I inhibitors, which in vitro inhibit complex I with IC 50 values 50 values between 1-10 nM. Lead compounds specifically induce apoptosis with EC 50 values between 1-10 nM in OXPHOS dependent cancer models such as AML and DLBCL cell lines and in glycolysis deficient cancer cell lines. Of note, apoptosis is induced in primary AML cells but not in normal patient-derived CD34+ cells. These compounds are orally bioavailable with excellent pharmacokinetics properties in preclinical species making them appropriate tools for proof-of-concept studies in vivo. In agreement with data in cell culture, we have shown that daily oral treatment with as low as 5 -10 mg/kg of our OXPHOS inhibitors is well tolerated and induce strong regression of NB-1 (glycolysis-deficient cells) subcutaneous and intracranial xenografts. We have also demonstrated that sustained pharmacological inhibition of OXPHOS induce regression of DLBCL subcutaneous models and dramatically increase mice survival in an OCI-AML3 orthotopic xenograft model. In addition to synthetic lethality in monotherapy, we are exploring whether OXPHOS inhibition can overcome resistance to radiotherapy, chemotherapy and specific targeted therapies. Taken together, these data strongly support the notion that inhibiting OXPHOS in hypersensitive populations could be a novel, innovative therapeutic approach and justifies evaluation of OXPHOS inhibitors in a clinical setting. Citation Format: Joseph R. Marszalek, Madhavi Bandi, Jennifer Bardenhagen, Christopher Bristow, Christopher Carroll, Edward Chang, Ninping Feng, Barbara Czako, Jason Gay, Mary Geck Do, Jennifer Greer, Ryan M. Johnson, Marina Konopleva, Zhijun Kang, Gang Liu, Timothy Lofton, Timothy McAfoos, Marina Protopopova, Alessia Petrocchi, Florian Muller, Jay Theroff, Yuanqing Wu, Lynda Chin, Giulio Draetta, Philip Jones, Carlo Toniatti, Emilia Di Francesco. Identification of OXPHOS inhibitors which selectively kill tumors with specific metabolic vulnerabilities. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 949. doi:10.1158/1538-7445.AM2014-949