Evidence for a novel, effective approach to targeting carcinoma catabolism exploiting the first-in-class, anti-cancer mitochondrial drug, CPI-613

PLoS ONE · 2022 · 4 citations

• Biology
• Cancer research
• Cell biology

Clinical targeting of the altered metabolism of tumor cells has long been considered an attractive hypothetical approach. However, this strategy has yet to perform well clinically. Metabolic redundancy is among the limitations on effectiveness of many approaches, engendering intrinsic single-agent resistance or efficient evolution of such resistance. We describe new studies of the multi-target, tumor-preferential inhibition of the mitochondrial tricarboxylic acid (TCA) cycle by the first-in-class drug CPI-613® (devimistat). By suppressing the TCA hub, indispensable to many metabolic pathways, CPI-613 substantially reduces the effective redundancy of tumor catabolism. This TCA cycle suppression also engenders an apparently homeostatic accelerated, inefficient consumption of nutrient stores in carcinoma cells, eroding some sources of drug resistance. Nonetheless, sufficiently abundant, cell line-specific lipid stores in carcinoma cells are among remaining sources of CPI-613 resistance in vitro and during the in vivo pharmacological drug pulse. Specifically, the fatty acid beta-oxidation step delivers electrons directly to the mitochondrial electron transport system (ETC), by-passing the TCA cycle CPI-613 target and producing drug resistance. Strikingly, tested carcinoma cell lines configure much of this fatty acid flow to initially traverse the peroxisome enroute to additional mitochondrial beta-oxidation. This feature facilitates targeting as clinically practical agents disrupting this flow are available. Two such agents significantly sensitize an otherwise fully CPI-613-resistant carcinoma xenograft in vivo. These and related results are strong empirical support for a potentially general class of strategies for enhanced clinical targeting of carcinoma catabolism.

Abstract 2867: FDG-PET imaging as a potential biomarker of mitochondrial targeting by CPI-613, a novel inhibitor of mitochondrial metabolism

Cancer Research · 2017-07-01 · 1 citations

Abstract CPI-613 is a lipoate analogue that has been shown to inhibit the pyruvate dehydrogenase (PDH) and alpha-ketoglutarate dehydrogenase (KGDH) complexes selectively in tumor cells (reviewed in Exp.Rev.Clin.Pharma. 7, 837). These two enzymes control the vast majority of carbon flow into the tricarboxylic acid (TCA) cycle and play a central role in mitochondrial metabolism. PDH converts pyruvate into acetyl-CoA, which in turn can enter the TCA cycle for cellular respiration. Since pyruvate is the final product of glycolysis, PDH serves to link glycolysis to the TCA cycle. Early clinical trials with CPI-613 have demonstrated very promising clinical responses in pancreatic cancer, leukemia, and lymphoma when used in combination with standard chemotherapy. Moreover, apparently homeostatic responses of tumor cells to CPI-613 inhibition of mitochondrial metabolism include compensatory upregulation of glucose uptake. Thus, we hypothesized that we can use 18F-Fludeoxyglucose (FDG)-PET/CT, a translational imaging approach that measures cellular glucose uptake, as a biomarker for CPI-613 cellular delivery and its targeting of mitochondrial metabolism. Therefore, in this work we evaluated the in vitro and in vivo glucose uptake in cancer cells and tumor xenografts after treatment with CPI-613. To measure glucose uptake in vitro we pulsed BxPc3 pancreatic cancer cells with 3H 2-deoxyglucose for 15 or 60 minutes following 2 hours of treatment with CPI-613. We observed a significant upregulation (~100% increase) of cellular 2-deoxyglucose uptake, consistent with a compensatory increase in glucose uptake as a result of successful targeting of mitochondrial metabolism. We therefore examined whether this upregulation occurs in vivo using FDG-PET/CT. Mice bearing BxPc3 flank tumors were treated with 50mg/kg of CPI-613 and underwent FDG-PET/CT scans 4 hours and 24 hours post-CPI-613 treatment. Similar to the in vitro response, tumors treated with CPI-613 exhibited a 75% increase in 18F-FDG uptake compared to untreated controls at 4 hours post therapy. In the 24 hour post-therapy scans, tumor 18F-FDG was significantly decreased, indicating tumor cell killing, which corresponds to previously published data that demonstrated efficacy of CPI-613 against BxPc3 tumor xenografts. These results indicate the potential for using the initial FDG flare seen on PET imaging as a biomarker to detect mitochondrial targeting by CPI-613 immediately after CPI-613 treatment, a strategy that may be used, after further clinical validation, to stratify responders to this novel mitochondrial inhibitor. Citation Format: Kiran Solingapuram Sai, Zuzana Zachar, Frankis Almaguel, Shawn D. Stuart, Michael S. Dahan, Moises Guardado, Stephanie Rideout, Minghui Wang, Anirudh Sattiraju, Paul M. Bingham, Boris Pasche, Akiva Mintz. FDG-PET imaging as a potential biomarker of mitochondrial targeting by CPI-613, a novel inhibitor of mitochondrial metabolism [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 2867. doi:10.1158/1538-7445.AM2017-2867

Abstract A61: Tumor metabolic remodeling can modulate anticancer drug response: CPI-613 attack on tumor cell mitochondrial metabolism is mediated by metabolite availability

Molecular Cancer Research · 2016-01-01

Abstract We will describe recent progress in understanding the role of cancer metabolic remodeling in determining the response of tumors and tumor cells to a novel, first-in-class clinical agent class selectively targeting cancer cell mitochondrial metabolism. The reconfiguration of mitochondrial metabolism in cancer in general, and the tricarboxylic acid (TCA) cycle in particular, presents a rich source of potential therapeutic targets. Pyruvate dehydrogenase (PDH) and alpha ketoglutarate dehydrogenase (KGDH) are two gatekeeper enzymes regulating carbon flux into the mitochondrial TCA cycle. A key component of the altered regulatory processes in cancer is lipoic acid (lipoate), which not only functions as a cofactor for both PDH and KGDH, but also as source of regulatory information. Moreover, the lipoate-sensitive regulatory components of PDH and KGDH are substantially reconfigured in tumor cells, providing cancer-specific targets that can be successfully attacked with properly designed lipoate analogs. We developed and characterized CPI-613, a lipoic acid analog, which selectively targets mitochondrial metabolism in tumor cells by mobilizing lipoate-sensitive, cancer-specific regulation of PDH and KGDH, shutting down the two enzymes and thereby choking carbon flow through the TCA cycle. This attack on mitochondrial metabolism redundantly activates multiple cell death pathways (Zachar, et al., 2011, J Mol Med 89, 1137; Stuart, et al., 2014, Cancer&Metab 2, 4). In vitro, CPI-613 is uniformly effective in killing tumor cell lines (more than 50 tumor lines tested to date). Moreover, these drugs have produced compelling clinical responses (including complete remissions) in some, but not all patients with advanced, refractory, heavily pre-treated cancers in initial Phase I/II clinical trials (Pardee et al., 2014, Clin Cancer Res 20:5255). In an effort to explore the mechanisms of CPI-613 activity and characterize the reasons for differential patient responses, we have shown that the kinetics of the cancer cell death response to CPI-613 is profoundly affected by the carbon sources available to the cell (Zachar, et al., 2011, J Mol Med 89, 1137). For example, in media where pyruvate and glutamine (capable of producing net ATP synthesis only in the mitochondrial compartment) are the major carbon sources, death is rapid, completed within 4 hours (op cit). In contrast, when glucose is substituted for pyruvate, the cell death programs take up to 48 hours to complete. We have analyzed the mechanistic basis of this and related observations, including steady state and flux metabolomics, pharmacological inhibitors of non-TCA metabolic pathways, and manipulation of media composition to systematically characterize these dramatic effects of nutrient availability on cancer cell drug response. Our results demonstrate that CPI-613 induced inactivation of tumor cell KGDH is modulated by the potency of mitochondrial redox detoxification (Stuart, et al., 2014, Cancer&Metab 2, 4). Given that various metabolic pathways (for example, glycolysis) can ultimately contribute to mitochondrial ROS detoxification potential, it appears that substrate availability powerfully influences the cellular response to CPI-613. These insights open a number of fundamentally new approaches to increasing the fraction of patients who respond strongly to CPI-613 in the clinic. We will also report pre-clinical studies targeted at allowing planned future clinical trials to exploit these new insights. Citation Format: Shawn D. Stuart, Moises Guardado, Michael Dahan, Paul M. Bingham, Zuzana Zachar. Tumor metabolic remodeling can modulate anticancer drug response: CPI-613 attack on tumor cell mitochondrial metabolism is mediated by metabolite availability. [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 A61.

Lipoic acid and lipoic acid analogs in cancer metabolism and chemotherapy

Expert Review of Clinical Pharmacology · 2014-10-04 · 50 citations

The lipoic acid (lipoate) coenzyme is unique in all of mammalian metabolism. It is not only crucial to the function of some of the major enzymes feeding carbon into the tricarboxylic acid cycle, but also generates dynamic regulatory information about the metabolic status of the mitochondrial matrix, ultimately functioning to control these metabolic fluxes. Moreover, these lipoate-sensitive regulatory processes are apparently systematically redesigned in tumor cells and the affected enzymes commonly become especially central to cancer metabolism. Thus, lipoate-sensitive regulatory processes constitute potentially uniquely valuable targets for chemotherapeutic attack. Our goal here is to review the current status of our knowledge relevant to the use of lipoate and lipoate analogs to therapeutically attack malignant disease.

A strategically designed small molecule attacks alpha-ketoglutarate dehydrogenase in tumor cells through a redox process

Cancer & Metabolism · 2014-03-10 · 181 citations

BACKGROUND: Targeting cancer cell metabolism is recognized as a promising arena for development of cancer chemotherapeutics. Moreover, redox metabolism is also systematically altered in tumor cells. Indeed, there is growing reason to believe that tumor-specific alteration of redox control of metabolism will be central to understanding and attacking malignancy. We report here that lipoate analog CPI-613 attacks a gate-keeping, lipoate-using metabolic enzyme, alpha-ketoglutarate dehydrogenase (KGDH), by a redox mechanism selectively in tumors cells. RESULTS: CPI-613 inhibited KGDH function strongly and rapidly, selectively in tumor cells. Moreover, CPI-613 induced a correspondingly rapid, powerful redox signal in tumor cell mitochondria. This signal was associated with redox modification of KGDH (including extensive enzyme glutathionylation and redox blockage of enzyme lipoate sulfhydryls), correlating with KGDH inactivation. The source of this tumor-specific mitochondrial redox modulatory signal was not electron transport complexes (I or III), but was largely or entirely the E3 (dihydrolipoamide dehydrogenase) component of dehydrogenases, including KGDH. Finally, we demonstrated that KGDH activity was redox regulated (in tumor cells), as expected if a tumor-specific redox process (auto)regulates KGDH. CONCLUSIONS: Our data demonstrate that lipoate analog CPI-613 attacks redox control of KGDH activity in tumor cells, perhaps by modulation of an existing lipoate-sensitive allosteric process normally governing tumor cell KGDH activity. Together with its previously reported, mechanistically distinct (non-redox) effects on the other major, lipoate-using mitochondrial metabolic enzyme, pyruvate dehydrogenase, CPI-613's KGDH effects indicate that this agent simultaneously attacks multiple central, essential components of tumor cell metabolic regulation.

Cancer Metabolism: A Nexus of Matter, Energy, and Reactive Oxygen Species

Cancer drug discovery and develogment/Cancer drug discovery and development · 2014-01-01 · 2 citations

Abstract 1122: Lipoic acid analogs induce ROS, leading to potent mitochondrial enzyme inhibition, metabolic dysfunction and cell death in tumor cells

Cancer Research · 2012-04-01

Abstract The targeting of tumor cell metabolism has emerged as an attractive candidate for chemotherapeutics. In particular, tumor cell mitochondria are dramatically reprogrammed to generate large amounts of biosynthetic intermediates to fuel cell division. We previously described a novel class of non-redox active lipoic acid analogs (“thioctoids”) which effect dramatic inactivation of the mitochondrial enzyme complex pyruvate dehydrogenase (PDH) (PMID:21769686). We have recently completed a comprehensive metabolomic study indicating that thioctoids down-regulate multiple mitochondria-associated enzymes. Each of these target enzymes are key control points for entry of carbon into the TCA cycle, including the alpha-ketoglutarate dehydrogenase complex and the branch-chain dehydrogenase/amino trasferase complex. In addition we will present data that reactive oxygen species (ROS) play a direct regulatory role in these inactivations and are a major contributor to the resultant cell cycle arrest and multiple cell death pathways which follow. Taken together, our results indicate that thioctoids are potent inhibitors of tumor cell mitochondrial energy metabolism, owing, apparently, to the central regulatory role of lipoic acid in mitochondrial lipoamide dehydrogenase-containing enzyme complexes. We hypothesize that thioctoids are ‘misread’ by these complexes resulting in increased levels of ROS leading to the further shutdown of redox-sensitive metabolic enzymes and ultimately cell death. As a consequence of these novel properties, thioctoids attack tumor-specific metabolism far more broadly and pervasively than other agents directed at individual metabolic steps or activities. Thioctoids are exceptionally well tolerated in animal studies and as a result may have high clinical potential. They are currently in early stage human clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1122. doi:1538-7445.AM2012-1122

Non-redox-active lipoate derivates disrupt cancer cell mitochondrial metabolism and are potent anticancer agents in vivo

Journal of Molecular Medicine · 2011-07-18 · 218 citations