Inhibition Of Pyruvate Dehydrogenase Research Articles

Andrographolide suppresses aerobic glycolysis and induces apoptotic cell death by inhibiting pyruvate dehydrogenase kinase 1 expression.

Metabolic disorder is a major characteristic of cancer cells, and controlling genes involved in metabolic shifts can be an effective strategy for cancer treatment. Andrographolide (AG), a diterpenoid lactone, is widely recognized as a natural anticancer drug due to its ability to inhibit cancer growth. The present study aimed to investigate the mechanism underlying the mitochondrial‑mediated anticancer effect of AG by inhibiting pyruvate dehydrogenase kinase 1 (PDK1) expression in lung cancer cells. Cells were treated with AG and PDK1 mRNA and protein expression was determined using reverse transcription‑quantitative PCR and western blotting, respectively. As a result, AG significantly inhibited the viability of human lung cancer cells and suppressed aerobic glycolysis by decreasing lactate generation. AG further decreased the PDK1 protein and mRNA levels in a dose‑dependent manner. AG‑induced cell death was assessed by flow cytometry and fluorescence microscopy. AG induced apoptotic cell death that was associated with the cleavage of poly (ADP ribose) polymerase, activation of caspase‑3, and mitochondrial damage, which was associated with an increase in reactive oxygen species and loss of mitochondrial membrane potential. AG‑induced cell death was partially suppressed via PDK1 overexpression in lung cancer cells. Therefore, the anticancer effects of AG on human lung cancer cells may negatively regulate the expression of PDK1.

Acylation of the rat brain proteins is affected by the inhibition of pyruvate dehydrogenase <i>in vivo</i>

Organism adaptation to metabolic challenges requires coupling of metabolism to gene expression. In this regard, acylations of histones and metabolic proteins acquire significant interest. We hypothesize that adaptive response to inhibition of a key metabolic process, catalyzed by the acetyl-CoA-generating pyruvate dehydrogenase (PDH) complex, is mediated by changes in the protein acylations. The hypothesis is tested by intranasal administration to animals of PDH-specific inhibitors acetyl(methyl)phosphinate (AcMeP) or acetylphosphonate methyl ester (AcPMe), followed by the assessment of physiological parameters, brain protein acylation, and expression/phosphorylation of PDHA subunit. At the same dose, AcMeP, but not AcPMe, decreases acetylation and increases succinylation of the brain proteins with apparent molecular masses of 15-20 kDa. Regarding the proteins of 30-50 kDa, a strong inhibitor AcMeP affects acetylation only, while a less efficient AcPMe mostly increases succinylation. The unchanged succinylation of the 30-50 kDa proteins after the administration of AcMeP coincides with the upregulation of desuccinylase SIRT5. No significant differences between the levels of brain PDHA expression, PDHA phosphorylation, parameters of behavior or ECG are observed in the studied animal groups. The data indicate that the short-term inhibition of brain PDH affects acetylation and/or succinylation of the brain proteins, that depends on the inhibitor potency, protein molecular mass, and acylation type. The homeostatic nature of these changes is implied by the stability of physiological parameters after the PDH inhibition.

Pyruvate Dehydrogenase Inhibition Leads to Decreased Glycolysis, Increased Reliance on Gluconeogenesis and Alternative Sources of Acetyl-CoA in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive disease characterized by poor outcomes and therapy resistance. Devimistat is a novel agent that inhibits pyruvate dehydrogenase complex (PDH). A phase III clinical trial in AML patients combining devimistat and chemotherapy was terminated for futility, suggesting AML cells were able to circumvent the metabolic inhibition of devimistat. The means by which AML cells resist PDH inhibition is unknown. AML cell lines treated with devimistat or deleted for the essential PDH subunit, PDHA, showed a decrease in glycolysis and decreased glucose uptake due to a reduction of the glucose transporter GLUT1 and hexokinase II. Both devimistat-treated and PDHA knockout cells displayed increased sensitivity to 2-deoxyglucose, demonstrating reliance on residual glycolysis. The rate limiting gluconeogenic enzyme phosphoenolpyruvate carboxykinase 2 (PCK2) was significantly upregulated in devimistat-treated cells, and its inhibition increased sensitivity to devimistat. The gluconeogenic amino acids glutamine and asparagine protected AML cells from devimistat. Non-glycolytic sources of acetyl-CoA were also important with fatty acid oxidation, ATP citrate lyase (ACLY) and acyl-CoA synthetase short chain family member 2 (ACSS2) contributing to resistance. Finally, devimistat reduced fatty acid synthase (FASN) activity. Taken together, this suggests that AML cells compensate for PDH and glycolysis inhibition by gluconeogenesis for maintenance of essential glycolytic intermediates and fatty acid oxidation, ACLY and ACSS2 for non-glycolytic production of acetyl-CoA. Strategies to target these escape pathways should be explored in AML.

Acylation of the Rat Brain Proteins is Affected by the Inhibition of Pyruvate Dehydrogenase in vivo.

Organism adaptation to metabolic challenges requires coupling of metabolism to gene expression. In this regard, acylations of histones and metabolic proteins acquire significant interest. We hypothesize that adaptive response to inhibition of a key metabolic process, catalyzed by the acetyl-CoA-generating pyruvate dehydrogenase (PDH) complex, is mediated by changes in the protein acylations. The hypothesis is tested by intranasal administration to animals of PDH-specific inhibitors acetyl(methyl)phosphinate (AcMeP) or acetylphosphonate methyl ester (AcPMe), followed by the assessment of physiological parameters, brain protein acylation, and expression/phosphorylation of PDHA subunit. At the same dose, AcMeP, but not AcPMe, decreases acetylation and increases succinylation of the brain proteins with apparent molecular masses of 15-20 kDa. Regarding the proteins of 30-50 kDa, a strong inhibitor AcMeP affects acetylation only, while a less efficient AcPMe mostly increases succinylation. The unchanged succinylation of the 30-50 kDa proteins after the administration of AcMeP coincides with the upregulation of desuccinylase SIRT5. No significant differences between the levels of brain PDHA expression, PDHA phosphorylation, parameters of behavior or ECG are observed in the studied animal groups. The data indicate that the short-term inhibition of brain PDH affects acetylation and/or succinylation of the brain proteins, that depends on the inhibitor potency, protein molecular mass, and acylation type. The homeostatic nature of these changes is implied by the stability of physiological parameters after the PDH inhibition.

Open-chain thiamine analogues as potent inhibitors of thiamine pyrophosphate (TPP)-dependent enzymes.

A common approach to studying thiamine pyrophosphate (TPP)-dependent enzymes is by chemical inhibition with thiamine/TPP analogues which feature a neutral aromatic ring in place of the positive thiazolium ring of TPP. These are potent inhibitors but their preparation generally involves multiple synthetic steps to construct the central ring. We report efficient syntheses of novel, open-chain thiamine analogues which potently inhibit TPP-dependent enzymes and are predicted to share the same binding mode as TPP. We also report some open-chain analogues that inhibit pyruvate dehydrogenase E1-subunit (PDH E1) and are predicted to occupy additional pockets in the enzyme other than the TPP-binding pockets. This opens up new possibilities for increasing the affinity and selectivity of the analogues for PDH, which is an established anti-cancer target.

PDK1- and PDK2-mediated metabolic reprogramming contributes to the TGFβ1-promoted stem-like properties in head and neck cancer

BackgroundResistance to chemotherapeutic drugs is a key factor for cancer recurrence and metastases in head and neck cancer (HNC). Cancer stem cells (CSCs) in tumors have self-renewal, differentiation, and higher drug resistance capabilities, resulting in a poor prognosis for patients. In glucose metabolism, pyruvate dehydrogenase kinase (PDK) inhibits pyruvate dehydrogenase and impedes pyruvate from being metabolized into acetyl-CoA and entering the tricarboxylic acid cycle to generate energy. Studies have reported that PDK1 and PDK2 inhibition suppresses the growth, motility, and drug resistance of cancer cells. Furthermore, while TGFβ1 levels are persistently elevated in HNC patients with poor prognosis, the role of PDK isoforms in the TGFβ1-promoted progression and stem-like properties of HNC is unclear.MethodsLevels of PDK1 and PDK2 were evaluated in HNC tissue microarrays by immunohistochemistry to explore potential clinical relevance. PDK1 and PDK2 were knocked down by the lentivirus shRNA system to investigate their role in TGFβ1-promoted tumor progression in vitro.ResultsWe found that PDK2 levels were increased in the later stage of HNC tissues compared to constant PDK1 expression. After PDK1 and PDK2 knockdown, we discovered increased ATP production and decreased lactate production in TGFβ1-treated and untreated HNC cells. However, only PDK2 silencing significantly inhibited the clonogenic ability of HNC cells. We subsequently found that TGFβ1-promoted migration and invasion capabilities were decreased in PDK1 and PDK2 knockdown cells. The tumor spheroid-forming capability, motility, CSC genes, and multidrug-resistant genes were downregulated in PDK1 and PDK2 silencing CSCs. PDK1 and PDK2 inhibition reversed cisplatin and gemcitabine resistance of CSCs, but not paclitaxel resistance.ConclusionThe results demonstrated that the PDK1- and PDK2-mediated Warburg effect contributes to the TGFβ1-enhanced stemness properties of HNC. Therefore, PDK1 and PDK2 may serve as molecular targets for the combination therapy of HNC.

Nitric oxide regulation of cellular metabolism: Adaptive tuning of cellular energy

Nitric oxide can interact with a wide range of proteins including many that are involved in metabolism. In this review we have summarized the effects of NO on glycolysis, fatty acid metabolism, the TCA cycle, and oxidative phosphorylation with reference to skeletal muscle. Low to moderate NO concentrations upregulate glucose and fatty acid oxidation, while higher NO concentrations shift cellular reliance toward a fully glycolytic phenotype. Moderate NO production directly inhibits pyruvate dehydrogenase activity, reducing glucose-derived carbon entry into the TCA cycle and subsequently increasing anaploretic reactions. NO directly inhibits aconitase activity, increasing reliance on glutamine for continued energy production. At higher or prolonged NO exposure, citrate accumulation can inhibit multiple ATP-producing pathways. Reduced TCA flux slows NADH/FADH entry into the ETC. NO can also inhibit the ETC directly, further limiting oxidative phosphorylation. Moderate NO production improves mitochondrial efficiency while improving O2 utilization increasing whole-body energy production. Long-term bioenergetic capacity may be increased because of NO-derived ROS, which participate in adaptive cellular redox signaling through AMPK, PCG1-α, HIF-1, and NF-κB. However, prolonged exposure or high concentrations of NO can result in membrane depolarization and opening of the MPT. In this way NO may serve as a biochemical rheostat matching energy supply with demand for optimal respiratory function.

Single-Cell RNA-Sequencing of 245 Tumor Samples from Patients with MGUS and Smoldering Multiple Myeloma Reveals Novel Insights into Malignant Plasma Cell Biology

Introduction Patients with Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Multiple Myeloma (SMM) exhibit variable risk of progression to full-blown Multiple Myeloma (MM), which cannot be fully explained by differences in tumor burden or genetic alterations. Therefore, characterizing non-genetic changes in malignant plasma cells may help to identify novel mechanisms of disease progression and improve prognostication. Our current understanding of transcriptomic alterations in patients with MGUS and SMM is based on bulk RNA-sequencing or microarray studies, which are affected by sample purity and interpatient variability. Here, we present results from the largest single-cell RNA-sequencing cohort (n=245) of tumor samples from patients with MGUS and SMM. Methods We performed single-cell RNA- and V(D)J-sequencing on 245 samples from 36 patients with MGUS, 136 patients with SMM, 37 patients with MM, and 25 healthy donors. Libraries were prepared with the Chromium Single-cell 5' and V(D)J enrichment kit by 10X Genomics and sequenced on NovaSeq at the Genomics Platform of the Broad Institute of MIT and Harvard (Cambridge, MA). CellRanger v.6.0.1. was used to extract FASTQ files and produce count matrices. Droplets with more than 15% of UMIs mapped to mitochondrial genes or fewer than 200 detected genes were removed, and doublets were identified using Scrublet, SCDS, and scDblFinder. Samples were integrated using Harmony, and plasma cells were annotated as malignant or normal based on the matched V(D)J clonotype information. Differential expression was performed at the single-cell level using Wilcoxon's rank-sum test. Results Overall, we sequenced 1,318,218 plasma cells, including 960,998 malignant and 357,220 normal plasma cells. Each patient's tumor formed a unique cluster, and tumors with similar cytogenetics clustered adjacent to each other. By comparing expression levels between malignant and normal plasma cells for each patient, we were able to identify differentially expressed genes per tumor and assess how frequently each gene is dysregulated across the cohort. This approach can provide a rationale for the prioritization of target validation and can potentially uncover clinically meaningful differences between disease stages. As hypothesized, our analysis recovered established markers of plasma cell malignancy that are useful diagnostically, such as the downregulation of CD27 (rank 1), CD99 (rank 2), and CD81 (rank 5), or therapeutically, such as the upregulation of GPRC5D (rank 9). Moreover, we discovered frequent downregulation of SH3BGRL3 (rank 3), a gene associated with cell migration, and SSR4 (rank 9), SELENOK (rank 11), OSTC (rank 15), and SPCS3 (rank 18), genes associated with protein folding and the regulation of endoplasmic reticulum (ER) stress. Interestingly, PDK1 (rank 17), an inhibitor of pyruvate dehydrogenase that is highly expressed in normal plasma cells, was frequently downregulated in malignant plasma cells, suggesting that the balance between oxidative phosphorylation and aerobic glycolysis may be different in malignant plasma cells. The most common upregulated genes were the oncogene MLLT3 (rank 1), the growth factor IGF1 (rank 2), and the proteasome regulator TJP1 (rank 3). By comparing the frequency of dysregulation between patients with SMM and MGUS, we observed that malignant plasma cells from patients with SMM were more likely to upregulate MYC, which is concordant with the known increase in MYC genetic alterations as the disease progresses. Furthermore, patients with SMM are more likely to show upregulation of CD47, which promotes immune evasion. Lastly, patients with MM were more likely to exhibit upregulation of the RNA helicase DDX21, the therapeutic target SLAMF7, the ER factor TXNDC11, and NFkB signaling factors PIM2 and IRF9, compared to patients with SMM. Discussion In conclusion, by leveraging the largest single-cell RNA-sequencing cohort of bone marrow samples from patients with MGUS and SMM, we uncovered novel insights into plasma cell malignancy, as well as differences in gene expression dysregulation between disease stages. Observations gleaned from this dataset could be used to nominate novel targets and prioritize target validation for the development of novel therapeutics for the treatment or prevention of MM.

Altered glycolysis triggers impaired mitochondrial metabolism and mTORC1 activation in diabetic β-cells

Chronic hyperglycaemia causes a dramatic decrease in mitochondrial metabolism and insulin content in pancreatic β-cells. This underlies the progressive decline in β-cell function in diabetes. However, the molecular mechanisms by which hyperglycaemia produces these effects remain unresolved. Using isolated islets and INS-1 cells, we show here that one or more glycolytic metabolites downstream of phosphofructokinase and upstream of GAPDH mediates the effects of chronic hyperglycemia. This metabolite stimulates marked upregulation of mTORC1 and concomitant downregulation of AMPK. Increased mTORC1 activity causes inhibition of pyruvate dehydrogenase which reduces pyruvate entry into the tricarboxylic acid cycle and partially accounts for the hyperglycaemia-induced reduction in oxidative phosphorylation and insulin secretion. In addition, hyperglycaemia (or diabetes) dramatically inhibits GAPDH activity, thereby impairing glucose metabolism. Our data also reveal that restricting glucose metabolism during hyperglycaemia prevents these changes and thus may be of therapeutic benefit. In summary, we have identified a pathway by which chronic hyperglycaemia reduces β-cell function.

A phase 2a trial investigating ninerafaxstat – a novel cardiac mitotrope for the treatment of diabetic cardiomyopathy (IMPROVE-DiCE)

Abstract Background Type 2 diabetes (T2D) is a significant, independent contributor to the development of heart failure (HF), driven by energetic, metabolic, structural and functional myocardial changes. The T2D heart is characterised by over-reliance on fatty acid utilisation, shows reduced glucose oxidation and inhibition of pyruvate dehydrogenase (PDH). This results in a diminished myocardial energy reserve and blunted adenosine triphosphate (ATP) generation as well as cardiac steatosis, contributing to lipotoxicity, and diastolic dysfunction. Purpose We assessed the effects of ninerafaxstat – a novel cardiac mitotrope designed to shift myocardial substrate utilisation in favour of glucose and thus, restore myocardial energy homeostasis – on cardiac metabolism & diastolic function in patients with T2D and obesity. Methods In this open-label, mechanistic phase 2a trial, we enrolled 21 patients with T2D & obesity (HbA1c median 7.0% (IQR 6.6, 7.8), weight 97kg (90, 102)) and subsequently treated them with 200mg ninerafaxstat twice daily for 4 or 8 weeks; (Fig. 1). Cardiac metabolism and function were assessed pre- & post-treatment using magnetic resonance imaging (MRI), 31P-, 1H- and, in a subset of n=9, hyperpolarized [1-13C]pyruvate MR spectroscopy. Results T2D patients at baseline presented with impaired myocardial energetics with a markedly reduced PCr/ATP (1.6 [1.4, 2.1]), myocardial steatosis (myocardial triglycerides 2.2% [1.5, 3.2]) left ventricular (LV) hypertrophy (LV mass 130g [98, 152]), and diastolic dysfunction (peak diastolic strain rate 0.86 1/s [0.82, 1.06]). Ninerafaxstat significantly improved myocardial energetics (PCr/ATP median by 32%, p<0.01), reduced myocardial triglyceride content (by 34%, p=0.03) and improved LV diastolic function (peak circumferential diastolic strain rate by 10%, peak LV filling rate by 11%, both p<0.05) (Fig. 2). PDH flux was increased in 7/9 subjects (mean 45%, p=0.08), consistent with improved glucose utilisation. Left ventricular volumes and mass, heart rate and blood pressure remained unchanged. Conclusions Treatment with ninerafaxstat significantly improves myocardial energetics, reduces myocardial steatosis and improves diastolic function in patients with T2D and obesity. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Imbria Pharmaaceuticals

Alpha-Lipoic Acid Protects Against Doxorubicin-Induced Cardiotoxicity by Regulating Pyruvate Dehydrogenase Kinase 4.

As a widely used anti-tumor anthracycline, the accumulation of Doxorubicin (DOX) in body causes irreparable cardiomyocyte damage and therefore is limited in clinical application. Strategies to prevent from DOX-associated cardiotoxicity are urgent for patients who undergo DOX-based chemotherapy. Since oxidative stress injury being the major reason for myocardial toxicity of DOX, here we demonstrated that, Alpha-lipoic acid (ALA), which is a reductive agent, plays a cardioprotective role in attenuating DOX-induced cardiotoxicity by inhibiting pyruvate dehydrogenase kinase 4 (PDK4) expression. In vivo, the beneficial effect of ALA was evidenced by increased survival rate, mechanical contraction, and oxidative phosphorylation, while decreased reactive oxidative species (ROS) and apoptosis. In vitro, PDK4 overexpression remarkably increased DOX-induced apoptosis and ROS production in H9C2 cells. Notably, the protective effect of ALA was abrogated by PDK4 overexpression. We further used PDK4 knockout mice to identify the role of PDK4 in DOX-induced cardiotoxicity. Results elicited that PDK4 deficiency showed a consistent effect in protecting DOX cardiotoxicity as ALA treatment, which was evidenced by restored redox homeostasis and mitochondrial metabolism, finally inhibited myocardial injury. In conclusion, the cardioprotective role of ALA against DOX cardiotoxicity was dependent on PDK4-mediated regulation of oxidative stress and mitochondria metabolism.

Sepsis, pyruvate, and mitochondria energy supply chain shortage.

Balancing high energy-consuming danger resistance and low energy supply of disease tolerance is a universal survival principle that often fails during sepsis. Our research supports the concept that sepsis phosphorylates and deactivates mitochondrial pyruvate dehydrogenase complex control over the tricarboxylic cycle and the electron transport chain. StimulatIng mitochondrial energetics in septic mice and human sepsis cell models can be achieved by inhibiting pyruvate dehydrogenase kinases with the pyruvate structural analog dichloroacetate. Stimulating the pyruvate dehydrogenase complex by dichloroacetate reverses a disruption in the tricarboxylic cycle that induces itaconate, a key mediator of the disease tolerance pathway. Dichloroacetate treatment increases mitochondrial respiration and ATP synthesis, decreases oxidant stress, overcomes metabolic paralysis, regenerates tissue, organ, and innate and adaptive immune cells, and doubles the survival rate in a murine model of sepsis.

Tumor cells dictate anti-tumor immune responses by altering pyruvate utilization and succinate signaling in CD8+ T cells

The tumor microenvironment (TME) is a unique metabolic niche that can inhibit Tcell metabolism and cytotoxicity. To dissect the metabolic interplay between tumors and Tcells, we establish an invitro system that recapitulates the metabolic niche of the TME and allows us to define cell-specific metabolism. We identify tumor-derived lactate as an inhibitor of CD8+ Tcell cytotoxicity, revealing an unexpected metabolic shunt in the TCA cycle. Metabolically fit cytotoxic Tcells shunt succinate out of the TCA cycle to promote autocrine signaling via the succinate receptor (SUCNR1). Cytotoxic Tcells are reliant on pyruvate carboxylase (PC) to replenish TCA cycle intermediates. By contrast, lactate reduces PC-mediated anaplerosis. The inhibition of pyruvate dehydrogenase (PDH) is sufficient to restore PC activity, succinate secretion, and the activation of SUCNR1. These studies identify PDH as a potential drug target to allow CD8+ Tcells to retain cytotoxicity and overcome a lactate-enriched TME.

Mitochondria-Targeting Polymer Micelle of Dichloroacetate Induced Pyroptosis to Enhance Osteosarcoma Immunotherapy.

Pyroptosis has been reported to improve the immunosuppressive tumor microenvironment and may be a strategy to enhance osteosarcoma treatment. The extent to which modulation of mitochondria could induce tumor pyroptosis to enhance immunotherapy has not been characterized. We synthesized a mitochondria-targeting polymer micelle (OPDEA-PDCA), in which poly[2-(N-oxide-N,N-diethylamino)ethyl methacrylate] (OPDEA) was used to target mitochondria and the conjugated dichloroacetate (DCA) was used to inhibit pyruvate dehydrogenase kinase 1 (PDHK1). This conjugate induced pyroptosis through initiation of mitochondrial oxidative stress. We found that OPDEA-PDCA targeted mitochondria and induced mitochondrial oxidative stress through the inhibition of PDHK1, resulting in immunogenic pyroptosis in osteosarcoma cell lines. Moreover, we showed that OPDEA-PDCA could induce secretion of soluble programmed cell death-ligand 1 (PD-L1) molecule. Therefore, combined therapy with OPDEA-PDCA and an anti-PD-L1 monoclonal antibody significantly suppressed proliferation of osteosarcoma with prolonged T cell activation. This study provided a strategy to initiate pyroptosis through targeted modulation of mitochondria, which may promote enhanced antitumor efficacy in combination with immunotherapy.

Metformin alleviates the cognitive impairment caused by aluminum by improving energy metabolism disorders in mice

Long-term exposure to environmental aluminum was found to be related to the occurrence and development of neurodegenerative diseases. Energy metabolism disorders, one of the pathological features of neurodegenerative diseases, may occur in the early stage of the disease and are of potential intervention significance. Here, sub-chronic aluminum exposure mouse model was established, and metformin was used to intervene. We found that sub-chronic aluminum exposure decreased the protein levels of phosphorylation AMPK (p-AMPK), glucose transporter 1 (GLUT1) and GLUT3, taking charge of glucose uptake in the brain, reduced the levels of lactate shuttle-related proteins monocarboxylate transporter 4 (MCT4) and MCT2, as well as lactate content in the cerebral cortex, while increased hypoxia-inducible factor-1α (HIF-1α) level to drive downstream pyruvate dehydrogenase kinase 1 (PDK1) expression, thereby inhibiting pyruvate dehydrogenase (PDH) activity, and ultimately led to ATP depletion, neuronal death, and cognitive dysfunction. However, metformin could rescue these injuries. Thus, it came to a conclusion that aluminum could damage glucose uptake, interfere with astrocyte-neuron lactate shuttle (ANLS), interrupt the balance in energy metabolism, and resulting in cognitive function, while metformin has a neuroprotective effect against the disorder of energy metabolism caused by aluminum in mice.

Phase 3, multicenter, randomized study of CPI-613 with modified FOLFIRINOX (mFFX) versus FOLFIRINOX (FFX) as first-line therapy for patients with metastatic adenocarcinoma of the pancreas (AVENGER500).

4023 Background: Metastatic pancreatic cancer (mPC) remains a deadly disease with very limited treatment options. FFX is a standard first-line therapy for mPC with a median overall survival (mOS) of 11.1 months. CPI-613 is a stable intermediate of a lipoate analog that inhibits pyruvate dehydrogenase and α-ketoglutarate dehydrogenase enzymes of the tricarboxylic cycle preferentially within the mitochondria of cancer cells. In a phase I study, CPI-613+mFFX was safe and exhibited promising signal of efficacy. Methods: A global, randomized phase 3 trial was conducted across 73 sites to investigate the efficacy and safety of CPI-613 in combination with mFFX compared to standard dose FFX in treatment-naïve patients with mPC. Treatment was administered in 2-weekly cycles until progression or intolerable toxicity. In the experimental arm, CPI-613 at 500 mg/m2 was given intravenously on days 1 and 3. The doses of irinotecan, oxaliplatin, and 5-fluorouracil in the experimental arm were 65 mg/m2, 140 mg/m2, and 2,400 mg/2, respectively. Primary endpoint was OS. Secondary endpoints were progression-free survival (PFS), overall response rate (ORR), duration of response, pharmacokinetics, patient reported outcomes and safety. Results: 528 patients were randomly assigned (266 in test and 262 in control arm). There were 362 deaths, with a mOS of 11.1 months for CPI-613+mFFX vs. 11.7 months for FFX [hazard ratio (HR), 0.95; 95% CI, 0.77 to 1.18; P = 0.655]; mPFS was 7.8 months vs. 8.0 months respectively [HR, 0.99; 95% CI, 0.76 to 1.29; P = 0.94]; ORR was 39% in the test arm vs. 34% in the control arm [ORR ratio, 1.23 (95% CI, 0.86 to 1.75)]. Grade ≥ 3 treatment-emergent adverse events with ≥ 10% frequency in CPI-613 plus mFFX vs. FFX arm were diarrhea (11.2% vs. 19.6%), hypokalemia (13.1% vs. 14.9%), anemia (13.9% vs. 13.6%), neutropenia (11.2% vs. 14.0%), thrombocytopenia (11.6% vs. 13.6%) and fatigue (10.8% vs. 11.5%). Conclusions: The addition of CPI-613 to mFFX failed to show significant improvements of ORR, PFS or OS. The mFFX in the test arm that had the lowest prospectively tested doses of FFX was without compromise on PFS or OS and may be considered as a reference for future FFX administration. Clinical trial information: NCT03504423.

Phase 1b results of a multicenter, randomized phase 1b/2 study of gemcitabine and cisplatin +/- CPI-613 as first-line therapy for patients with advanced biliary tract cancer (BilT-04).

4094 Background: Patients (pts) with advanced biliary tract cancers (BTC) have a poor prognosis despite systemic chemotherapy. Gemcitabine (G) and cisplatin (C) is a standard first-line systemic therapy with a reported overall response rate (ORR) of 26% and median overall survival (OS) of 11.7 months (mo). CPI-613/Devimistat (D) is a stable intermediate of a lipoate analog that inhibits pyruvate dehydrogenase and a-ketoglutarate dehydrogenase enzymes of the tricarboxylic (TCA) cycle, preferentially within the mitochondria of cancer cells augmenting chemotherapeutic cytotoxicity. Methods: An investigator-initiated, multi-institutional phase 1b/2 trial is underway across 10 sites in the US investigating the combination of G 1000 mg/m2, C 25 mg/m2 and D (dose levels: (-1) 500, (1) 1000, (2) 1500 and (3) 2000 mg/m2) (GCD) on days 1 and 8 every 21 days in pts with previously untreated advanced BTC. The primary objective of the phase 1b portion (n = 20 pts; TiTE-CRM methodology) was to determine the recommended phase 2 dose (RP2D). The primary objective of the ongoing phase 2 portion (n = 48-58 pts; 2:1 randomization with Bayesian control arm) is to determine the best ORR with an alternative hypothesis of 43% (null of 25%); with 80% power and one-sided alpha of 0.05. Secondary objectives include evaluation of progression-free survival (PFS), OS, and safety. Exploratory objectives include targeted exome/ transcriptomic analysis using tissue, and metabolomic analysis using plasma (pre-, on- and post-treatment). Results: 20 pts were enrolled on phase 1b; median age 65 years (range 43-75), ECOG PS 0/1 (9/11), male/female (11/9), Caucasian (85%), intrahepatic/hilar/distal cholangiocarcinoma and gallbladder (9/5/3/3), and metastatic/locally advanced stage (15/5). CPI-613 dose level assignments were 1 pt each for (-1) and (1), 2 pts on (2), and 16 pts on (3). Median follow-up was 9.4 mos and median number of cycles was 9. Only 1 pt had dose-limiting toxicity (grade 2 creatinine elevation). RP2D for CPI-613 was 2000 mg/m2. In phase 1b, ORR was 40% (7 PR, 1 CR). Median PFS not estimable (NE) but probability of PFS at 9 months was 68.1% [95% CI, 38.1%-85.8%]. Median OS is 16.3 months [95% CI, 9.1-NE]. One locally advanced pt was resected with pathologic CR. Conclusions: The combination of GCD was well tolerated and demonstrates encouraging efficacy with ORR, PFS and OS in phase 1b. The randomized phase 2 portion of the trial is open and accruing patients. Clinical trial information: NCT04203160.

Phase 1/2 study of devimistat in combination with hydroxychloroquine (HCQ) in patients with relapsed or refractory (R/R) clear cell sarcoma (CCS).

TPS11595 Background: CCS of the soft tissues is a rare and aggressive subtype of sarcoma that often starts in the tendons of the arms or legs. It is molecularly characterized by t(12;22)(q13;q12) translocation, resulting in EWSR1-ATF1 or EWSR1-CREB1 gene fusion. Despite reports of occasional responses to systemic therapies, currently available therapies have shown limited efficacy in advanced CCS. Therefore, there is a significant unmet medical need for more active agents in CCS. Devimistat is a stable intermediate of a lipoate analog that inhibits pyruvate dehydrogenase and α-ketoglutarate dehydrogenase enzymes of the tricarboxylic acid (TCA) cycle preferentially within the mitochondria of cancer cells. Devimistat induces autophagy in cancer cells. In a metastatic mouse model of CCS, treatment with devimistat in combination with chloroquine significantly suppressed tumor growth (Egawa et al, 2018). Based on this data, we hypothesized that inhibition of autophagy with HCQ may sensitize cancer cells to devimistat with increased efficacy and acceptable toxicity. Given its expected synergy, we have initiated a single-arm phase I/II prospective, multicenter, open-label, non-randomized study to evaluate maximally tolerated dose (MTD), safety, and efficacy of devimistat in combination with HCQ in patients with R/R CCS. Methods: In the phase 1 portion of the study, patients with R/R CCS and other fusion-positive R/R sarcomas will be enrolled and a standard 3+3 design will be followed to evaluate toxicity, MTD, and recommended phase 2 dose. There will be two patient groups based on weight, and dose escalation will be conducted separately for each group. Starting dose of HCQ will be 5mg/kg PO BID for patients < 45 kg and 200 mg PO BID for patients ≥45 kg on days 1 through 5 of every 28 days. The first dose of HCQ each day will be followed 2 hours later by 1,000 mg/m2 devimistat (for patients < 45 kg) and 2,000 mg/m2 of devimistat (for patients ≥ 45 kg) administered over 2 hours. A maximum of 36 patients will be enrolled for the phase I portion, 18 for each patient group. In the phase 2 portion of the study, only relapsed or refractory CCS patients will be enrolled, and the response rate will be determined using RECIST 1.1. In phase 2, pharmacokinetics, duration of response, clinical benefit rate, progression-free survival, overall survival, safety, and patient-reported outcomes will also be assessed. This portion of the study will utilize Simon’s admissible two-stage design with 29 patients. This study started enrolling participants in November 2021 and has dosed six patients to date. The first two dose-escalation cohorts for patients ≥45 kg have been completed without DLT and the third dose level will be opening shortly. Clinical trial information: NCT04593758.

Accumulation of Intramyocellular Acetylcarnitine is Associated with Glycolytic ATP Production In Vivo During Incremental Contractions in Human Skeletal Muscle

The interplay in vivo between muscle bioenergetics (ATP production) and intermediary metabolism in working skeletal muscle is not fully understood. During contractions, acetylcarnitine (AC) production may be an important modulator of energetic pathway and fuel selection for the support of ATP production. As contraction intensity and energetic demand increase, free carnitine in the mitochondria buffers excess acetyl‐CoA by converting it into AC and free CoA. This process enables greater flux of pyruvate into the mitochondria by lessening acetyl‐CoA’s product inhibition of pyruvate dehydrogenase. Further, as AC accumulates in the mitochondria, it will move into the cytosol, where by its conversion to malonyl‐CoA it can have the additional effect of inhibiting fatty acid translocation into the mitochondria. Here, a new method combining noninvasive magnetic resonance spectroscopic (MRS) measures of AC (by 1H MRS) with phosphorus MRS measures of ATP production was used to investigate the link between [AC] and energy production in vivo. Our primary aim was to test the novel hypothesis that AC accumulation during muscular work would be directly associated with nonoxidative (i.e., wherein the fate of pyruvate is lactate) glycolytic ATP production. Using a 3‐Tesla MR system with a dual‐tuned (1H/31P) surface coil, intracellular phosphorus metabolites and pH were measured in the vastus lateralis muscle of 8 males (mean 28.4 yr, range 25‐45) during 8 min of incremental isotonic contractions (0.5 Hz, 2‐min stages at 6, 9, 12, and 15% maximal torque). These metabolites and pH were then used to calculate ATP production (mM·s‐1) via oxidative phosphorylation, nonoxidative glycolysis, and the creatine kinase reaction (CK) throughout the contraction protocol. [AC] was measured in resting muscle pre‐ and post‐contractions. Spearman rank correlation coefficients (rs) were calculated to evaluate associations between post‐contraction [AC] and ATP production during the incremental protocol. On average, 13.1% (range 8.6 ‐ 17.3) of ATP production during the contraction protocol was from CK, 11.3% (0.4 ‐ 29.3) through glycolysis, and 75.6% (55.3 ‐ 90) by oxidative metabolism. [AC] increased > 5‐fold, from 4.4 mM pre‐contractions (1.6‐11.6, n = 7) to 22.5 mM post (13.6 ‐ 33.8, n = 8; p = 0.004). Post‐contraction [AC] was positively correlated with absolute (mM·s‐1) and relative (% total) glycolytic ATP production (rs = 0.95, p = 0.001), supporting our primary hypothesis. Notably, post‐contraction [AC] was negatively correlated with relative (rs = ‐0.81 p = 0.02) but not absolute (rs = ‐0.14, p = 0.75) oxidative ATP production. Thus, cytosolic AC accumulated more when there was greater reliance on glycolysis and a relatively lower overall contribution from oxidative metabolism – a situation consistent with a buildup of acetyl‐CoA in the mitochondria. These results demonstrate, for the first time, the connection between energetic pathway selection and a key metabolic intermediate in working muscle in vivo. Intramyocellular AC may be a valuable tool for probing muscle energetics, substrate utilization, and metabolic flexibility in the future.

Pyruvate Dehydrogenase Kinase Protects Dopaminergic Neurons from Oxidative Stress in Drosophila DJ-1 Null Mutants.

DJ-1 is one of the causative genes of early-onset familial Parkinson’s disease (PD). As a result, DJ-1 influences the pathogenesis of sporadic PD. DJ-1 has various physiological functions that converge to control the levels of intracellular reactive oxygen species (ROS). Based on genetic analyses that sought to investigate novel antioxidant DJ-1 downstream genes, pyruvate dehydrogenase (PDH) kinase (PDK) was demonstrated to increase survival rates and decrease dopaminergic (DA) neuron loss in DJ-1 mutant flies under oxidative stress. PDK phosphorylates and inhibits the PDH complex (PDC), subsequently downregulating glucose metabolism in the mitochondria, which is a major source of intracellular ROS. A loss-of-function mutation in PDK was not found to have a significant effect on fly development and reproduction, but severely ameliorated oxidative stress resistance. Thus, PDK plays a critical role in the protection against oxidative stress. Loss of PDH phosphatase (PDP), which dephosphorylates and activates PDH, was also shown to protect DJ-1 mutants from oxidative stress, ultimately supporting our findings. Further genetic analyses suggested that DJ-1 controls PDK expression through hypoxia-inducible factor 1 (HIF-1), a transcriptional regulator of the adaptive response to hypoxia and oxidative stress. Furthermore, CPI-613, an inhibitor of PDH, protected DJ-1 null flies from oxidative stress, suggesting that the genetic and pharmacological inhibition of PDH may be a novel treatment strategy for PD associated with DJ-1 dysfunction.