User-friendly relative quantification procedure for gas chromatography/mass spectrometry-based plasma metabolome analysis.

RATIONALE: Recently, metabolome analysis has been applied to a variety of research fields, but differences between batches or facilities can cause discrepancies in the results of such analyses. To resolve these issues using comprehensive metabolome analysis, in which it is difficult to perform quantitative analyses of all detected metabolites, internal standard compounds are used to obtain relative metabolite levels. This study investigated gas chromatography/mass spectrometry-based plasma metabolome analysis methods that are superior to relative quantification using internal standard compounds. METHODS: In experiment I, four analyses were performed under different analytical conditions at one facility, and then the data from the four analyses were compared. In experiment II, the same samples were analyzed at three facilities, and then the data from the three facilities were compared. RESULTS: Regarding the relative values obtained through comparisons with the internal standard compound, differences in the analytical results were observed among the four analytical conditions in experiment I and among the three facilities in experiment II, and the differences observed among the three facilities (experiment II) were larger. When correction was performed using plasma as a quality control, which is the procedure suggested in this study, these differences were markedly ameliorated. CONCLUSION: The suggested procedure involves the analysis of a plasma standard as a quality control for each batch and the calculation of relative target plasma to quality-control plasma values for each metabolite. This is an easy and low-cost method and could be readily employed by researchers during comprehensive plasma metabolome analysis.

Exploration of Metabolite Biomarkers to Predict the Efficacy of Dupilumab Treatment for Atopic Dermatitis.

Dupilumab (DUP) is the first biological agent used treating atopic dermatitis (AD). Notwithstanding its high cost, the type of patient group for which the drug is effective remains unclear. In this retrospective study, we aimed to identify novel and reliable biomarkers which can be measured before DUP administration and to predict the efficacy of DUP. Serum samples from 19 patients with AD treated with DUP were analysed by metabolome analysis using gas chromatography-mass spectrometry. Total 148 metabolites were detected, and the relative values of the metabolites were compared between the patient group that achieved 75% improvement in Eczema Area and Severity Index 16 weeks after administration of DUP (high responders: HR; n = 11) and that did not (low responders: LR; n = 8). The HR and LR groups had significant differences in the relative values of the eight metabolites (lactic acid, alanine, glyceric acid, fumaric acid, nonanoic acid, ribose, sorbitol, and ornithine), with ribose emerging as the best. Furthermore, we evaluated the serum concentrations of ribose and found that ribose may be a useful metabolite biomarker for predicting the efficacy of DUP in AD.

Itraconazole Modulates Phospholipid Levels in Tumor-associated Macrophages.

BACKGROUND/AIM: Itraconazole, an antifungal drug, repolarizes pro-tumorigenic M2 tumor-associated macrophages to anti-tumorigenic M1-like phenotypes, thereby inhibiting the proliferation of cancer cells; however, the underlying mechanism remains unclear. Therefore, we investigated the effect of itraconazole on membrane-associated lipids in tumor-associated macrophages (TAM). MATERIALS AND METHODS: M1 and M2 macrophages were derived from the human monocyte leukemia cell line (THP-1) and cultured with or without 10 µM itraconazole. Cells were homogenized and subjected to liquid chromatography/mass spectrometry (LC/MS) analysis to estimate the glycerophospholipid levels in the cells. RESULTS: Lipidomic analysis results, displayed on a volcano plot, revealed that itraconazole-induced altered phospholipid composition, with more pronounced changes in M2 macrophages than in M1. Notably, itraconazole significantly increased intracellular phosphatidylinositol and lysophosphatidylcholine levels in M2 macrophages. CONCLUSION: Itraconazole modulates the lipid metabolism of TAMs, which could have implications for the development of novel cancer therapies.

Comparative Evaluation of Plasma Metabolomic Data from Multiple Laboratories.

In mass spectrometry-based metabolomics, the differences in the analytical results from different laboratories/machines are an issue to be considered because various types of machines are used in each laboratory. Moreover, the analytical methods are unique to each laboratory. It is important to understand the reality of inter-laboratory differences in metabolomics. Therefore, we have evaluated whether the differences in analytical methods, with the exception sample pretreatment and including metabolite extraction, are involved in the inter-laboratory differences or not. In this study, nine facilities are evaluated for inter-laboratory comparisons of metabolomic analysis. Identical dried samples prepared from human and mouse plasma are distributed to each laboratory, and the metabolites are measured without the pretreatment that is unique to each laboratory. In these measurements, hydrophilic and hydrophobic metabolites are analyzed using 11 and 7 analytical methods, respectively. The metabolomic data acquired at each laboratory are integrated, and the differences in the metabolomic data from the laboratories are evaluated. No substantial difference in the relative quantitative data (human/mouse) for a little less than 50% of the detected metabolites is observed, and the hydrophilic metabolites have fewer differences between the laboratories compared with hydrophobic metabolites. From evaluating selected quantitatively guaranteed metabolites, the proportion of metabolites without the inter-laboratory differences is observed to be slightly high. It is difficult to resolve the inter-laboratory differences in metabolomics because all laboratories cannot prepare the same analytical environments. However, the results from this study indicate that the inter-laboratory differences in metabolomic data are due to measurement and data analysis rather than sample preparation, which will facilitate the understanding of the problems in metabolomics studies involving multiple laboratories.

Genome-wide association study of gastric cancer- and duodenal ulcer-derived Helicobacter pylori strains reveals discriminatory genetic variations and novel oncoprotein candidates.

Genome-wide association studies (GWASs) can reveal genetic variations associated with a phenotype in the absence of any hypothesis of candidate genes. The problem of false-positive sites linked with the responsible site might be bypassed in bacteria with a high homologous recombination rate, such as Helicobacter pylori, which causes gastric cancer. We conducted a small-sample GWAS (125 gastric cancer cases and 115 controls) followed by prediction of gastric cancer and control (duodenal ulcer) H. pylori strains. We identified 11 single nucleotide polymorphisms (eight amino acid changes) and three DNA motifs that, combined, allowed effective disease discrimination. They were often informative of the underlying molecular mechanisms, such as electric charge alteration at the ligand-binding pocket, alteration in subunit interaction, and mode-switching of DNA methylation. We also identified three novel virulence factors/oncoprotein candidates. These results provide both defined targets for further informatic and experimental analyses to gain insights into gastric cancer pathogenesis and a basis for identifying a set of biomarkers for distinguishing these H. pylori-related diseases.

Itraconazole Inhibits Intracellular Cholesterol Trafficking and Decreases Phosphatidylserine Level in Cervical Cancer Cells.

BACKGROUND/AIM: Itraconazole shows anticancer activity in various types of cancer but its underlying mechanism is unclear. We investigated the effect of itraconazole on membrane-associated lipids. MATERIALS AND METHODS: To investigate the influences of itraconazole on cholesterol trafficking, cervical cancer CaSki cells were cultured with itraconazole and analyzed by Filipin staining followed by confocal microscopy. Effect on the glycerophospholipid profiles was analyzed by liquid chromatography/mass spectrometry (LC/MS). RESULTS: After itraconazole treatment, Filipin staining revealed cholesterol accumulation in the intracellular compartments, which was similar to the distribution after treatment of U18666A (cholesterol transport inhibitor). LC/MS analysis showed a significant decrease in phosphatidylserine levels and an increase in lysophosphatidylcholine levels in CaSki cells. CONCLUSION: Itraconazole inhibited cholesterol trafficking and altered the phospholipid composition. Alterations in the cell membrane can potentiate the anticancer activity of itraconazole.

Effect of a High-Fat Diet on the Small-Intestinal Environment and Mucosal Integrity in the Gut-Liver Axis.

Although high-fat diet (HFD)-related dysbiosis is involved in the development of steatohepatitis, its pathophysiology especially in the small intestine remains unclear. We comprehensively investigated not only the liver pathology but also the microbiome profile, mucosal integrity and luminal environment in the small intestine of mice with HFD-induced obesity. C57BL/6J mice were fed either a normal diet or an HFD, and their small-intestinal contents were subjected to microbial 16S rDNA analysis. Intestinal mucosal permeability was evaluated by FITC-dextran assay. The levels of bile acids in the small-intestinal contents were measured by liquid chromatography/mass spectrometry. The expression of tight junction molecules, antimicrobial peptides, lipopolysaccharide and macrophage marker F4/80 in the small intestine and/or liver was examined by real-time RT-PCR and immunohistochemistry. The abundance of Lactobacillus was markedly increased and that of Clostridium was drastically decreased in the small intestine of mice fed the HFD. The level of conjugated taurocholic acid was significantly increased and those of deconjugated cholic acid/secondary bile acids were conversely decreased in the small-intestinal contents. The expression of occludin, antimicrobial Reg IIIß/γ and IL-22 was significantly decreased in the small intestine of HFD-fed mice, and the intestinal permeability was significantly accelerated. Infiltration of lipopolysaccharide was significantly increased in not only the small-intestinal mucosa but also the liver of HFD-fed mice, and fat drops were apparently accumulated in the liver. Pathophysiological alteration of the luminal environment in the small intestine resulting from a HFD is closely associated with minimal inflammation involving the gut-liver axis through disturbance of small-intestinal mucosal integrity.

Tumor resistance to ferroptosis driven by Stearoyl-CoA Desaturase-1 (SCD1) in cancer cells and Fatty Acid Biding Protein-4 (FABP4) in tumor microenvironment promote tumor recurrence.

PROBLEM: Tumor recurrence is a major clinical issue that represents the principal cause of cancer-related deaths, with few targetable common pathways. Mechanisms by which residual tumors persist and progress under a continuous shift between hypoxia-reoxygenation after neoadjuvent-therapy are unknown. In this study, we investigated the role of lipid metabolism and tumor redox balance in tumor recurrence. METHODS: Lipidomics, proteomics and mass spectrometry imaging approaches where applied to mouse tumor models of recurrence. Genetic and pharmacological inhibitions of lipid mediators in tumors were used in vivo and in functional assays in vitro. RESULTS: We found that stearoyl-CoA desaturase-1 (SCD1) expressed by cancer cells and fatty acid binding protein-4 (FABP4) produced by tumor endothelial cells (TECs) and adipocytes in the tumor microenvironment (TME) are essential for tumor relapse in response to tyrosine kinase inhibitors (TKI) and chemotherapy. SCD1 and FABP4 were also found upregulated in recurrent human breast cancer samples and correlated with worse prognosis of cancer patients with different types of tumors. Mechanistically, SCD1 leads to fatty acid (FA) desaturation and FABP4 derived from TEM enhances lipid droplet (LD) in cancer cells, which cooperatively protect from oxidative stress-induced ferroptosis. We revealed that lipid mobilization and desaturation elicit tumor intrinsic antioxidant and anti-ferroptotic resources for survival and regrowth in a harsh TME. Inhibition of lipid transport from TME by FABP4 inhibitor reduced tumor regrowth and by genetic - or by pharmacological - targeting SCD1 in vivo, tumor regrowth was abolished completely. CONCLUSION: This finding unveils that it is worth taking advantage of tumor lipid addiction, as a tumor vulnerability to design novel treatment strategy to prevent cancer recurrence.

Possibility of detecting intraductal papillary mucinous neoplasms using metabolite biomarkers for pancreatic cancer.

Aim: The aim of this study was to identify whether metabolite biomarker candidates for pancreatic cancer (PC) could aid detection of intraductal papillary mucinous neoplasms (IPMN), recognized as high-risk factors for PC. Materials & methods: The 12 metabolite biomarker candidates, which were found to be useful to detect PC in our previous study, were evaluated for plasma samples from patients with PC (n = 44) or IPMN (n = 24) or healthy volunteers (n = 46). Results: Regarding the performance of individual biomarkers of PC and PC high-risk IPMN, lysine exhibited the best performance (sensitivity: 67.8%; specificity: 86.9%). The multiple logistic regression analysis-based detection model displayed high sensitivity and specificity values of 92.5 and 90.6%, respectively. Conclusion: Metabolite biomarker candidates for PC are useful for detecting high-risk IPMN, which can progress to PC.

Prospective Study Using Plasma Apolipoprotein A2-Isoforms to Screen for High-Risk Status of Pancreatic Cancer.

Apolipoprotein A2-ATQ/AT (apoA2-ATQ/AT) has been identified as a minimally invasive biomarker for detecting pancreatic cancer (PC) and high-risk (HR) individuals for PC. To establish an efficient enrichment strategy for HR, we carried out a plasma apoA2-ATQ/AT level-based prospective screening study among the general population. The subjects for the screening study were recruited at six medical check-up facilities in Japan between October 2015 and January 2017. We evaluated the positive predictive value (PPV) of the plasma apoA2-ATQ/AT level of ≤35 µg/mL for detecting PC and HR. Furthermore, we prospectively confirmed its diagnostic accuracy with another post-diagnosis population in a cross-sectional study. We enrolled 5120 subjects in experimental screening, with 84 subjects (1.3%) showing positive results for apoA2-ATQ/AT. Pancreatic abnormalities were recognized in 26 of the 84 subjects from imaging examinations. Pancreatic abnormalities detected included 1 PC and 15 HR abnormalities, such as cystic lesions including intraductal papillary mucinous neoplasm. The PPV of apoA2-ATQ/AT for detecting PC and HR was 33.3%. Moreover, a combination study with another cross-sectional study revealed that the area under the curve for apoA2-ATQ/AT to distinguish PC from healthy controls was 0.903. ApoA2-ATQ/AT has the potential to enrich PC and HR by increasing the diagnostic probability before imaging examinations.

Adrenic acid induces oxidative stress in hepatocytes.

Adrenic acid (ADA), which is an endogenously synthesized polyunsaturated free fatty acid, was significantly increased in nonalcoholic fatty liver disease (NAFLD) patients and NAFLD-model mice compared with the corresponding controls in our previous study. To elucidate the involvement of ADA in NAFLD and nonalcoholic steatohepatitis (NASH), we examined ADA-induced lipotoxicity in human hepatocarcinoma HepG2 cells. The ROS production in HepG2 cells was increased by exposure to ADA. It was also shown that the treatment with ADA decreased cell viability in a dose-dependent manner. The N-Acetyl-L-Cysteine pretreatment counteracted this ADA-induced ROS production and cell death. Furthermore, ADA modulated the expressions of SOD2, HO-1 and Gpx1 as antioxidant enzymes. These findings suggest that ADA could induce oxidative stress accompanied by cell death, providing new insights into lipotoxicity that is involved in the pathogenesis of NAFLD and NASH.

Detection of Novel Amino Acid Polymorphisms in the East Asian CagA of Helicobacter Pylori with Full Sequencing Data.

Cytotoxin-associated gene A (CagA) is generally accepted to be the most important virulence factor of Helicobacter pylori and increases the risk of developing gastric cancer. East Asian CagA, which includes the EPIYA-D segment at the C-terminal region, has a significantly higher gastric carcinogenic rate than Western CagA including the EPIYA-C segment. Although the amino acid polymorphism surrounding the EPIYA motif in the C-terminal region has been examined in detail, limited information is currently available on the amino acid polymorphism of the N-terminal region of East Asian CagA. In the present study, we analyzed the sequencing data of East Asian CagA that we obtained previously to detect amino acid changes (AACs) in the N-terminal region of East Asian CagA. Four highly frequent AACs in the N-terminal region of East Asian CagA were detected in our datasets, two of which (V356A, Y677F) exhibited reproducible specificity using a validation dataset from the NCBI database, which are candidate AACs related to the pathogenic function of CagA. We examined whether these AACs affect the functions of CagA in silico model. The computational docking simulation model showed that binding affinity between CagA and phosphatidylserine remained unchanged in the model of mutant CagA reflecting both AAC, whereas that between CagA and α5ß1 integrin significantly increased. Based on whole genome sequencing data we herein identified novel specific AACs in the N-terminal regions of EPIYA-D that have the potential to change the function of CagA.

Effects of differences in pre-analytical processing on blood protein profiles determined with SWATH-MS.

The purpose of the present study was to assess the differences between the human serum and plasma proteomes, and the stability of human plasma proteins under different storage conditions following blood collection, by means of SWATH-MS analysis. When we compared plasma and serum prepared immediately after blood sampling, 95.5% of 176 quantified proteins differed by less than 1.5-fold. When we compared plasma samples prepared by centrifugation after storage of blood at room temperature for 0, 15 or 30 min, or under refrigeration at 0-5 °C for 1, 4 or 8 h, no protein showed a significant change (q < 0.05) that amounted to 1.5-fold or more, except hemoglobins. Those proteins were greatly increased in a single sample at 8 h, probably due to hemolysis. Comparison of data from the same samples indicates that the blood proteome is more stable than the blood metabolome. The present results suggest that most components of the proteome are essentially the same in plasma and serum, and are stable under the storage conditions examined in the present study. However, it may be important to pay attention to the extent of coagulation, and levels of platelet and hemolysis-related proteins. SIGNIFICANCE: Pre-analytical processing and storage conditions after blood collection are expected to influence the blood proteome. Therefore, we investigated differences in the proteome between human serum and plasma, as well as the stability of human plasma proteins under different storage conditions: at room temperature for 0-30 min, or at 0-5 °C for 1-8 h, which may reflect the clinical situation of blood collection. Proteomics analysis with SWATH-MS identified 342 proteins, and 176 proteins quantified with two or more unique peptides were compared. The levels of most components of the proteome were similar in plasma and serum, and were stable under the storage conditions examined. However, it is necessary to consider the possibility of coagulation, as this affects the levels of platelet and hemolysis-related proteins. Interestingly, the blood proteome appears to be more stable than the blood metabolome, based on previously reported metabolomics data with same samples. These data will be helpful in designing protocols for blood sampling and for blood biomarker discovery and validation.

Possible Involvement of Lipids in the Effectiveness of Kombu in Individuals with Abnormally High Serum Triglyceride Levels.

In Japan, Kombu (Laminaria japonica), which is a type of seaweed, is considered to be a foodstuff with health-promoting benefits, and Japanese people actively incorporate Kombu into their diets. Previously, we reported that the frequent intake of Kombu reduced the serum triglyceride levels of subjects with abnormally high serum triglyceride levels. In the current human study, we performed metabolomic analysis of serum lipids, and then the molecular species profiles of phosphatidylcholines (PC), phosphatidylethanolamines (PE), lysophosphatidylcholines (LPC), lysophosphatidylethanolamines (LPE), and free fatty acids (FFA) were evaluated. As a result, it was found that there were no marked differences between the lipid profiles obtained before and after the intake of Kombu for 4 wk in all subjects. In the subjects with abnormal serum triglyceride levels, the intake of Kombu improved the subjects' molecular species profiles in terms of their serum levels of the diacyl and acyl forms of PC, PE, LPC, and LPE, and FFA. Furthermore, the intake of Kombu also tended to increase the serum levels of both the plasmanyl and plasmenyl forms of PC and PE in these subjects. The lipid alterations observed in our study might be related to the functionality of Kombu. Furthermore, it is important to evaluate the quality of lipids as well as the quantity of lipids in various types of research, including food functionality studies.

Effects of Helicobacter pylori on the glutathione-related pathway in gastric epithelial cells.

Virulence factors of Helicobacter pylori (H. pylori) are diverse, so various biological responses happen in a host infected with H. pylori. The aim of this study is to conduct the metabolomics-based evaluation on H. pylori infection. AGS human gastric carcinoma cells were infected with H. pylori strain 26695, and then the altered metabolite pathways in the infected AGS cells were analyzed by metabolomics. Metabolites related to the glutathione (GSH) cycle were downregulated by H. pylori infection. Next, we evaluated the effects of H. pylori on the GSH-related pathway in AGS cells infected with H. pylori isolated from patients with atrophic gastritis (AG), duodenal ulcer (DU) and gastric cancer (GC). We found that the declined degree of GSH levels and oxidative stress were greater in AGS cells infected with GC strains than DU and AG-derived strains. There were no significant differences in almost mRNA expressions of GSH-related factors among different clinical strains, but the protein expression of glutathione synthetase was lower in AGS cells infected with GC-derived strains than DU and AG-derived strains. Our data demonstrates that GC-derived H. pylori-induced oxidative stress in a host is stronger and GC-derived strains may have suppressive influences on the host's GSH-related defense systems.

GC/MS and LC/MS-based Tissue Metabolomic Analysis Detected Increased Levels of Antioxidant Metabolites in Colorectal Cancer.

Late-stage colorectal cancer is resistant to current treatments. Understanding the biological processes responsible for the development and progression of colorectal cancer could aid the development of new diagnostic and treatment approaches. We used gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry-based metabolomic analysis to measure metabolite levels in pairs of colorectal cancer tissue samples and samples of the adjacent macroscopically normal mucosal tissue from 10 colon cancer patients. Regarding nucleotide metabolomic intermediates, the colorectal cancer tissue contained lower levels of ribulose 5-phosphate and higher levels of xanthine, adenine, and hypoxanthine than the normal tissue. The levels of antioxidant metabolites, such as sulfur-containing amino acids, were also significantly higher in the colorectal cancer tissue. The level of tryptophan was decreased, and the levels of molecules downstream of the tryptophan pathway, such as kynurenine and quinolinic acid, which protect colorectal cancer against the host's immune system and function in de novo nicotinamide adenine dinucleotide synthesis, were increased in the colorectal cancer tissue. The colorectal cancer tissue samples also contained higher levels of lysophospholipids and fatty acids, especially stearic acid and polyunsaturated fatty acids, including arachidonic acid and docosahexaenoic acid. Thus, understanding these cancer-specific alterations could make it possible to detect colorectal cancer early and aid the development of additional treatments for the disease, leading to improvements in colorectal cancer patients' quality of life.

ß-hydroxybutyrate protects hepatocytes against endoplasmic reticulum stress in a sirtuin 1-independent manner.

ß-hydroxybutyrate (BHB), a major ketone body in mammals, is produced from fatty acids through mitochondrial fatty acid oxidation in hepatocytes. To elucidate the role of BHB in the hepatic endoplasmic reticulum (ER), we examined the effects of BHB on hepatic ER stress induced by tunicamycin. In mouse hepatoma Hepa1c1c7 cells, BHB treatment suppressed the protein expression of ER stress responsive genes and increased cell viability, while reducing the protein expression of apoptosis inducible genes, without causing any alterations in the protein expression of sirtuin 1 (SIRT1) or the phosphorylation of AMP-activated protein kinase. The intraperitoneal administration of BHB also reduced the protein expression of ER stress responsive genes in mouse livers. In human hepatoma HepG2 cells, the protein expression levels of ER stress responsive genes were increased by the partial inhibition of BHB production with siRNA targeting endogenous 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) lyase, whereas they were decreased by promoting BHB production with fenofibrate. These findings revealed that BHB helps to suppress hepatic ER stress via a SIRT1-independent pathway, and it might be possible to manipulate ER stress by regulating BHB production genetically or pharmacologically.

Serum level of octanoic acid predicts the efficacy of chemotherapy for colorectal cancer.

The survival times of patients with advanced colorectal cancer (CRC) have increased due to the introduction of chemotherapy involving irinotecan and cetuximab. However, further studies are required on the effective pretreatment methods for identifying patients with CRC who would respond to particular treatments. The aim of the present study was to identify biomarkers for predicting the efficacy of chemotherapy for CRC. A total of 123 serum samples were collected from 31 patients with CRC just prior to each of the first four rounds of chemotherapy. Serum metabolome analysis was performed using a multiplatform metabolomics system, and univariate Cox regression hazards analysis of the time to disease progression was conducted. Octanoic acid and 1,5-anhydro-D-glucitol were identified as biomarker candidates. In addition, the serum level of octanoic acid was indicated to be significantly associated with the time to disease progression (hazard ratio, 3.3; 95% confidence interval, 1.099-11.840; P=0.033). The serum levels of fatty acids, in particular polyunsaturated fatty acids, tended to be downregulated in the partial response group. The findings of the present study suggest that the serum level of octanoic acid may serve as a useful predictor for the prognosis of CRC.

Metabolomics-based Discovery of Serum Biomarkers to Predict the Side-effects of Neoadjuvant Chemoradiotherapy for Esophageal Squamous Cell Carcinoma.

BACKGROUND/AIM: Neoadjuvant chemoradiotherapy has side-effects that adversely affect patients' quality of life. The aim of this study was to identify serum metabolite biomarkers that might be used to predict the side-effects of neoadjuvant chemoradiotherapy for esophageal squamous cell carcinoma (ESCC). PATIENTS AND METHODS: Metabolomic analysis of serum samples from 26 patients with ESCC that were collected before neoadjuvant chemoradiotherapy was performed. The metabolites associated with hematological toxicity or nephrotoxicity were evaluated. RESULTS: Serum levels of glutaric acid, glucuronic acid, and cystine were significantly higher in hematological toxicity, and phosphatidylcholines and phosphatidylethanolamines exhibited a tendency to be higher in those with hematological toxicity. The serum level of pyruvic acid was significantly lower in nephrotoxicity, and lysophosphatidylcholines and lysophosphatidylethanolamines tended to be lower in those with nephrotoxicity. CONCLUSION: Our study found that serum levels of some metabolites differed significantly between patients with and without hematological or renal side-effects. These metabolites may be useful biomarkers for predicting hematological toxicity or nephrotoxicity after neoadjuvant chemoradiotherapy for ESCC.