Tandem Mass Spectrometry Research Articles

PSV-20 Mycotoxin contamination trends in United States corn grain: 2019-2023

Abstract Mycotoxins are secondary fungal metabolites which may affect animal health, reproduction, and performance. These naturally occurring toxic metabolites are found in a variety of feedstuffs worldwide. Classic signs of mycotoxicosis in livestock can include reduced feed intake, diarrhea, and vomiting. Consideration of clinical signs alone will underestimate the true impact of mycotoxins on animals as inflammation, decreased nutrient digestibility, impaired gut integrity, and altered immune responses have also been associated with mycotoxin exposure. The objective of this study was to compare mycotoxin contamination levels of the 2023 corn crop with previous year trends. Samples were analyzed utilizing the liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for six major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A (OTA). Statistical analyses were performed with JMP Pro 16 software using one-way ANOVA and means were separated using Tukey’s HSD with significance reported at P ≤ 0.05. A limited number of 2023 samples were screened by time of abstract submission (n = 37); therefore, the contamination profile of this crop year will likely change as the sample pool expands and includes more samples originating from the Midwest. Contamination levels in corn for the tested toxin groups have remained consistent over the survey period. To date, 100% of the samples evaluated contained at least one mycotoxin, compared with 91% that was observed in 2022. Aflatoxin occurrence was numerically greater in 2023 corn compared with previous harvest years (27 vs. 11, 7, 5, and 3%, 2022 through 2019, respectively) while Afla mean contamination levels were similar across the study period (P > 0.05). The occurrence of FUM in 2023 corn was also numerically the greatest (97 vs. 79, 64, 64, and 78%, 2022 through 2019, respectively) and mean FUM contamination levels did not differ across the study period (P > 0.05). Occurrence of A-Trich was numerically increased in 2023 vs. 2022 (22 vs. 3%) but mean contamination level of positive samples for A-Trich was significantly less (P < 0.05) in 2023 vs. 2019 (21 vs. 330 parts per billion) and did not differ from other years in the study. The occurrence of B-Trich was numerically less in 2023 vs. 2022 (35 vs. 68%) while B-Trich mean contamination levels were similar across the study period (P > 0.05). Preliminary results of the 2023 US corn grain survey indicate mycotoxin occurrence is numerically increased while mean contamination levels are similar for most mycotoxin groups other than A-Trich. Continued surveillance is advised to assess the risk to livestock as new crop corn is fed out over the coming months.

Self-reported caffeine consumption miss-matched consumption measured by plasma levels of caffeine and its metabolites: results from two population-based studies.

Self-reported caffeine consumption has been widely used in research while it may be subject to bias. We sought to investigate the associations between self-reported caffeine consumption and plasma levels of caffeine and its two main metabolites (paraxanthine and theophylline) in the community. Data from two population-based studies (SKIPOGH1 and 2 (N = 1246) and CoLaus|PsyCoLaus (N = 4461)) conducted in Switzerland were used. Self-reported caffeine consumption was assessed using questionnaires. Plasma levels of caffeine and its metabolites were quantified by ultra-high performance liquid chromatography coupled to a tandem quadrupole mass spectrometer. In both studies, mean log plasma levels of caffeine and its two metabolites were over 6.48 (plasma levels = 652 ng/ml) when no caffeine consumption was reported. Subsequently, nonlinear associations between log plasma levels and self-reported caffeine consumption were observed in SKIPOGH, with a change of the slope at 3-5 cups of espresso per day in SKIPOGH1 but not SKIPOGH2. In CoLaus|PsyCoLaus, increased daily consumption of caffeinated beverages was associated with increased log plasma levels with a change of the slope at 3 cups. In both studies, declared caffeine consumption higher than 3-5 cups per day was not associated with higher plasma levels of caffeine and its metabolites. Self-reports of no or low caffeine consumption and consumption of more than 3-5 cups of coffee should be interpreted with caution, with possible under- or over-estimation. Quantifying plasma levels of caffeine and its metabolites may contribute to a better estimation of caffeine intake.

Prenatal ochratoxin A exposure, birth outcomes and infant growth in rural Burkina Faso: A human biomonitoring sub-study from the MISAME-III trial

Mycotoxin exposure during pregnancy has been associated with adverse birth outcomes and poor infant growth in low- and middle-income countries. We assessed multiple biomarkers and metabolites of exposure to mycotoxins during pregnancy and their associations with birth outcomes and infant growth in 305 pregnant participants, between 30 and 34 completed weeks of gestation, in rural Burkina Faso. In this study, whole blood microsamples were analyzed for mycotoxin concentrations using ultra-performance liquid chromatography coupled to tandem mass spectrometry. Unadjusted and adjusted associations between mycotoxin exposure, and birth outcomes and infant growth at 6 months were estimated using linear regression models for continuous outcomes and linear probability models with robust variance estimation for binary outcomes. Infant growth trajectories from birth to 6 months were compared by exposure status using mixed-effects models with random intercept for the individual infant and random slope for the infant's age. Ochratoxin A (OTA) exposure was detected in 50.8 % of the study participants, with aflatoxin G1, aflatoxin M1, cyclopiazonic acid, deoxynivalenol and T-2-toxin being detected in the range of 0.33 % and 2.31 % of the population. We found no statistically significant (p ≥ 0.05) associations between OTA exposure, and birth outcomes and infant growth. Despite this, the findings indicate a significant presence of ochratoxin A among pregnant participants. Public health policies and nutrition-sensitive interventions must ensure that OTA exposure is reduced in Burkina Faso.

Analyzing DNA barcoding and identifying toxins caused by neurotoxic mushroom poisoning using liquid chromatography tandem mass spectrometry

Background: Neurotoxic mushroom poisoning often exhibits rapid symptom onset, typically attributed to compounds such as Ibotenic acid, which affect the central nervous system. This study addresses a new case of mushroom-related food poisoning in southern Thailand. Objective: The objectives are to determine the presence of ibotenic acid in cases of mushroom-related food poisoning utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS) and to identify toxic Amanita species implicated in these cases. Materials and methods: Remnant mushroom samples obtained from three clinically reported cases were used. Nucleotide similarity was compared against the rRNA/ ITS databases using NCBI BLAST search. Phylogenetic analyses were conducted using maximum likelihood (ML) and FastTree approaches. LC-MS/MS was employed to separate of Ibotenic acid, determine its molecular weight and perform precursor ion fragmentation. Results: Analysis of the rRNA/ITS databases revealed a high nucleotide similarity between suspected mushroom samples and Amanita digitosa. Detailed phylogenetic analysis confirmed that mushroom samples from the three poisoning cases clustered with A. digitosa. LC-MS/MS analysis showed the presence of ibotenic acid, with precursor ion (m/z 159) and product ion (m/z 113.1) as the major toxic substances. Clinically, patients poisoned by ibotenic acid-containing mushrooms exhibited a short latent period with symptoms of nausea, vomiting, vertigo, delirium, confusion, and fatigue. Conclusion: The genus Amanita comprises both edible and inedible species that produce several lethal toxins. The report of ibotenic acid in A. digitosa is a novel finding, valuable for food safety monitoring and healthcare decision-maker. This is especially notable due to the accuracy and rapidity of the analytical process.

Measurement of Serum Vitamins B2 and B6 in Patients with Hashimoto’s Thyroiditis by LC–MS/MS Method

Vitamin B2 and vitamin B6 are cofactors and coenzymes in many biochemical reactions, and their sufficient serum concentrations may be crucial for the proper functioning of the thyroid gland. The aim of the study was to develop and validate a novel high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the determination of vitamin B2 and vitamin B6 in the serum of patients with Hashimoto’s thyroiditis (HT). Detection of the analytes was performed on a triple-quadrupole MS with multiple reaction monitoring using electrospray ionization. The mobile phase consisted of water and methanol, both containing 0.1% (v/v) formic acid. The analytes were isolated from serum by the one-step sample preparation of the trichloroacetic acid precipitation. Validation parameters, including linearity, accuracy, precision, limits of detection and quantification, and stability, were determined and fulfilled the criteria for analyzing compounds in biological fluids. The method was applied for the determination of the above vitamin concentrations in serum samples of 74 patients with HT and 33 healthy controls. The concentration of vitamin B2 was significantly lower in patients with HT compared to the control group (7.20 ± 7.86 ng/mL vs. 12.03 ± 9.62 ng/mL) and the concentration of vitamin B6 was also lower, but without a statistically significant difference (30.09 ± 19.16 ng/mL vs. 37.29 ± 23.02 ng/mL). We concluded that the vitamins concentration measurement may be helpful in the diagnosis of vitamin deficiencies and the supplementation strategy.

Exploring the fragmentation efficiency of proteins analyzed by MALDI-TOF-TOF tandem mass spectrometry using computational and statistical analyses.

Matrix-assisted laser desorption/ionization time-of-flight-time-of-flight (MALDI-TOF-TOF) tandem mass spectrometry (MS/MS) is a rapid technique for identifying intact proteins from unfractionated mixtures by top-down proteomic analysis. MS/MS allows isolation of specific intact protein ions prior to fragmentation, allowing fragment ion attribution to a specific precursor ion. However, the fragmentation efficiency of mature, intact protein ions by MS/MS post-source decay (PSD) varies widely, and the biochemical and structural factors of the protein that contribute to it are poorly understood. With the advent of protein structure prediction algorithms such as Alphafold2, we have wider access to protein structures for which no crystal structure exists. In this work, we use a statistical approach to explore the properties of bacterial proteins that can affect their gas phase dissociation via PSD. We extract various protein properties from Alphafold2 predictions and analyze their effect on fragmentation efficiency. Our results show that the fragmentation efficiency from cleavage of the polypeptide backbone on the C-terminal side of glutamic acid (E) and asparagine (N) residues were nearly equal. In addition, we found that the rearrangement and cleavage on the C-terminal side of aspartic acid (D) residues that result from the aspartic acid effect (AAE) were higher than for E- and N-residues. From residue interaction network analysis, we identified several local centrality measures and discussed their implications regarding the AAE. We also confirmed the selective cleavage of the backbone at D-proline bonds in proteins and further extend it to N-proline bonds. Finally, we note an enhancement of the AAE mechanism when the residue on the C-terminal side of D-, E- and N-residues is glycine. To the best of our knowledge, this is the first report of this phenomenon. Our study demonstrates the value of using statistical analyses of protein sequences and their predicted structures to better understand the fragmentation of the intact protein ions in the gas phase.

Simultaneous Analysis of 272 Pesticides in Agricultural Products by the QuEChERS Method and Gas Chromatography with Tandem Mass Spectrometry.

The aim of this study is to develop a rapid and accurate method for simultaneous analysis of multi-residue pesticides and conduct pesticide monitoring in agricultural products produced by the production and distribution stage in Korea. The representative agricultural products were selected as brown rice, soybean, potato, mandarin, and green pepper and developed using gas chromatography with tandem mass (GC-MS/MS) for the analysis of 272 pesticide residues. The experimental samples were extracted by the QuEChERS-EN method and then cleaned up by using d-SPE, including MgSO4 and primary secondary amine (PSA) sorbents. The established method was validated in accordance with Codex CAC-GL/40, and the limit of quantitation (LOQ) was determined to be 0.01 mg/kg. A total of 243 pesticides satisfied the guidelines in five samples at three levels with values of 60 to 120% (recovery) and ≤45% (coefficient of variation, CV). The remaining 29 pesticides did not satisfy the guidelines, and these pesticides are expected to be used as a screening method for the routine inspection of agricultural products. As a result of analyzing 223 agricultural products in South Korea by applying the simultaneous analysis method, none of the detected levels in the samples exceeded the standard values based on maximum residue limits (MRLs). The developed method in this study will be used to inspect residual pesticides in agricultural products, and it is anticipated to contribute to the distribution of safe agricultural products to consumers.

Comprehensive clinical and genetic analyses of circulating bile acids and their associations with diabetes and its indices.

Bile acids (BAs) are cholesterol-derived compounds that regulate glucose, lipid, and energy metabolism. Despite their significance in glucose homeostasis, the association between specific BA molecular species and their synthetic pathways with diabetes mellitus (DM) is unclear. Here, we used a recently validated stable-isotope dilution highperformance liquid chromatography with tandem mass spectrometry (LC-MS/MS) method to quantify a panel of BAs in fasting plasma from subjects (n=2,145) and explored structural and genetic determinants of BAs linked to DM, insulin resistance and obesity. Multiple 12α-hydroxylated BAs were associated with DM [adjusted odds ratios (aORs):1.3-1.9 (all P<0.05)] and insulin resistance [aORs:1.3-2.2 (all P<0.05)]. Conversely, multiple 6a-hydroxylated BAs and isolithocholic acid (Iso-LCA) were inversely associated with DM and obesity [aORs:0.3-0.9 (all P<0.05)]. Genome-wide association studies (GWAS) revealed multiple genome-wide significant loci linked with nine of the 14 DM-associated BAs, including a locus for Iso-LCA (rs11866815). Mendelian randomization analyses showed genetically elevated DCA levels were causally associated with higher BMI, and Iso-LCA levels were causally associated with reduced BMI and DM risk. In conclusion, comprehensive large-scale quantitative mass spectrometry and genetics analyses show circulating levels of multiple structurally specific BAs, especially DCA and Iso-LCA, are clinically associated with and genetically linked to obesity and DM.

Discrimination of three commercial tuna species through species-specific peptides: From high-resolution mass spectrometry discovery to MRM validation

The risk of tuna adulteration is high driven by economic benefits. The authenticity of tuna is required to protect both consumers and tuna stocks. Given this, the study is designed to identify species-specific peptides for distinguishing three commercial tropical tuna species. The peptides derived from trypsin digestion were separated and detected using ultrahigh-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) in data-dependent acquisition (DDA) mode. Venn analysis showed that there were differences in peptide composition among the three tested tuna species. The biological specificity screening through the National Center for Biotechnology Information’s Basic Local Alignment Search Tool (NCBI BLAST) revealed that 93 peptides could serve as potential species-specific peptides. Finally, the detection specificity of species-specific peptides of raw meats and processed products was carried out by multiple reaction monitoring (MRM) mode based on a Q-Trap mass spectrometer. The results showed that three, one and two peptides of Katsuwonus pelamis, Thunnus obesus and Thunnus albacores, respectively could serve as species-specific peptides.

Ecological risk assessment of organochlorine pesticide residues in sediment samples from Lake Tana and Hayqe in Northwest Ethiopia

In most developing countries, including Ethiopia, the excessive use of toxic and persistent pesticides for agricultural and malaria control purposes poses a significant challenge. This study focuses on evaluating the concentration and ecological risks associated with organochlorine pesticides (OCPs) in the sediments of Lake Tana and Hayqe. Employing a laboratory-based cross-sectional approach, the residues of OCPs in sediment samples were extracted using the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method, followed by dispersive solid phase extraction cleanup (d-SPE) techniques and analyzed for 18 OCPs by gas chromatography coupled to tandem mass spectrometry (GC-MS). The risk Quotient (RQ) method was adopted for ecological risk assessments by using fish, daphnia, and algae as indicators. The concentration of OCPs ranged from 10.11 to 125.65 μg/kg and 10.96–45.17 μg/kg in Lake Tana and Hayqe, respectively. There was a statistically significant difference in the mean concentration of OCPs across the sampling sites in Lake Tana. Deltamethrin and lindane exhibit comparatively lower concentrations among the OCPs, whereas endrin, DDT, and their metabolites were the predominant pesticides in the study area, exceeding WHO and USEPA residue limits, except for endosulfan. Risk Quotient values ranged from 0.006 to 865.4 in Lake Tana and 0.005 to 729.9 in Lake Hayqe, indicating potential low to high ecological risks for aquatic organisms. High ecological risks are particularly evident in fish, daphnia, and algae species exposed to α and β-Endosulfan, DDT, and their metabolites, while specifically in daphnia, endrin poses high ecological risks. The ANOVA test revealed there were statistically significant differences (p-value <0.05) among sampling sites in Lake Tana and the mean values between Lake Tana and Lake Hayqe, underscoring the importance of addressing pesticide-related ecological concerns in the region.

Surface assisted laser desorption/ionization mass spectrometry of lithium cationized lignans – A tool for rapid screening of plant extracts

Lignans are one of the most widespread classes of plant secondary metabolites possessing unique biological activities. The search for new sources of such compounds, their screening and identification in plant biomass is an urgent task, requiring the use of advanced analytical methods. In the present study, matrix-free surface assisted laser desorption/ionization (SALDI) mass spectrometry was proposed for its solution. The combination of carbon nanocoating sputtered on a target plate with lithium cationization allowed obtaining high-quality mass spectra of eight coniferous wood lignans with different bonds between aromatic units (secoisolariciresinol, matairesinol, 7-hydroxymatairesinol, nortrachelogenin, pinoresinol, guaiacylglycerol-β-guaiacyl ether, dehydrodihydrodiisoeugenol, and divanillin). Three types of fragmentation methods (post-source decay, high- and low-energy collision induced dissociation) for the first time were implemented on two types of MALDI instruments. Regardless of tandem mass spectrometry technique, lignans demonstrated the similar fragmentation patterns including the cleavage of bonds between aromatic units with the formation of mostly lithiated product ions. The low-energy collision induced dissociation in quadrupole ion trap provided the most informative tandem mass spectra and multi-stage fragmentation capabilities in structural studies. On this basis, an approach to rapid, high-throughput, and low-cost screening and tentative identification of lignans including isomeric compounds in plant biomass was developed and successfully tested on real samples of pine, fir, spruce, and larch knotwood extracts.

A de novo Mutation (p.Gln277X) of Cyclin D2 is Responsible for a Child with Megalencephaly-Polymicrogyria-Polydactyly-Hydrocephalus Syndrome.

Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH), a type of overgrowth syndrome, is characterized by progressive megalencephaly, cortical brain malformations, and distal limb anomalies. Previous studies have revealed that the overactivity of the phosphatidylinositol 3-kinase-Protein kinase Bpathway and the increased cyclin D2 (CCND2) expression were the main factors contributing to this disease. Here, we present the case of a patient who exhibited megalencephaly, polymicrogyria, abnormal neuronal migration, and developmental delay. Serum tandem mass spectrometry and chromosome examination did not detect any metabolic abnormalities or copy number variants. However, whole-exome sequencing and Sanger sequencing revealed a de novo nonsense mutation (NM_001759.3: c.829C>T; p.Gln277X) in the CCND2 gene of the patient. Bioinformatics analysis predicted that this mutation may disrupt the structure and surface charge of the CCND2 protein. This disruption could potentially prevent polyubiquitination of CCND2, leading to its resistance against degradation. Consequently, this could drive cell division and growth by altering the activity of key cell cycle regulatory nodes, ultimately contributing to the development of MPPH. This study not only presents a new case of MPPH and expands the mutation spectrum of CCND2 but also enhances our understanding of the mechanisms connecting CCND2 with overgrowth syndromes.

Plasma lipidome differences in patients with and without significant carotid plaque

BackgroundAtherosclerosis is a major cause of ischemic stroke, and early detection of advanced atherosclerosis in the carotid artery is important for reducing morbidity and mortality. What is even more important is not only detection of atherosclerosis but early determination whether the patients are at high risk of an event with adverse effects as the size of the plaque does not necessarily reflect its potential to trigger such events. AimWe studied whether plasma lipidomics profile can be used as a diagnostic tool for stratification of stable or unstable plaques without the need of removing the carotid plaque. MethodsThis study used liquid chromatography high-resolution tandem mass spectrometry lipidomics to characterize lipid profiles in patients' plasma and found that patients with significant and complicated (vulnerable) atherosclerotic plaque had distinct lipid profiles compared to those with insignificant plaques. ResultsThe lipid classes that were most predictive of vulnerable plaque were lysophosphoethanolamines, fatty acyl esters of hydroxy fatty acids, free fatty acids, plasmalogens, and triacylglycerols. Most of these compounds were found decreased in plasma of patients with unstable plaques which enabled sufficient performance of a statistical model used for patient stratification. ConclusionsPlasma lipidomes measured by liquid chromatography-mass spectrometry show differences in patients with stable and unstable carotid plaques, therefore these compounds could potentially be used as biomarkers for unstable plaque in future clinical diagnosis.

Quantitative investigation of drug-drug interaction between bergenin and vilazodone in rats through UPLC-MS/MS assay

In this study, we firstly established and verified a method by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for the analysis of vilazodone and its metabolite M10 in rat plasma, then this method was used to explore the pharmacokinetics of vilazodone and M10 present or absence of 80 mg/kg bergenin in rats. Protein precipitation with acetonitrile was used to prepare the samples in this research. The mobile phase for liquid chromatography was consisted of 0.1% formic acid aqueous solution and acetonitrile. Brexpiprazole was used as the internal standard (IS), and the multiple reaction monitoring (MRM) mode was used for detection. The verification items required by the US Food and Drug Administration (FDA) guidelines such as selectivity, sensitivity, linearity, stability, recovery and matrix effect of this method were all met the standards. Besides, rats were used to explore the drug-drug interaction between vilazodone and bergenin, which were divided into two groups, and separately gavaged with the same-volume of carboxymethyl cellulose sodium (CMC-Na) solution and 80 mg/kg bergenin, respectively. The results showed that bergenin significantly affected the metabolism of vilazodone. It suggested that there was a potential drug-drug interaction between bergenin and vilazodone in rats. In clinical application, we should pay attention to the dose of vilazodone when in combination with bergenin.

Abstract RF01-02: A randomized Phase I pre-operative window trial of transdermal endoxifen in women planning mastectomy: evaluation of dermal safety, intra-mammary drug distribution, and biologic effects

Abstract Background: Breast cancer prevention requires only local exposure of the breast to active drug but oral preventive agents entail systemic exposure, with resultant adverse effects, limiting acceptance by high-risk women. Drug-delivery through the breast skin is an attractive option, but requires demonstration of dermal safety and drug distribution throughout the breast. We formulated the tamoxifen metabolite (E/Z)-endoxifen in a hydroalcoholic/oleic acid gel for transdermal delivery. We tested this in a placebo-controlled, double-blinded Phase I trial with dose escalation from 10 to 20 mg daily and evaluated dermal safety, intra-mammary drug distribution, and biologic effects in DCIS or invasive cancers. Methods: Women planning mastectomy for therapy for Stage 0-III breast cancer, or surgical risk reduction (N=32) were randomized (2:1) to placebo-gel or endoxifen-gel applied to the skin of both breasts for 3-5 weeks. Our primary endpoint, dermal safety was evaluated using the modified NCI Common Terminology Criteria for Adverse Events version 4. Endoxifen concentration, and modulation of circulating tamoxifen biomarkers were evaluated to demonstrate minimal systemic effects. Plasma and tissue concentration of endoxifen were determined using Liquid Chromatography – Tandem Mass Spectrometry. Tamoxifen-responsive circulating markers, insulin-like growth factor 1 (IGF1) and sex hormone-binding globulin (SHBG), were measured with enzyme-linked immunosorbent assays. Finally, we explored anti-cancer efficacy in tumors by measuring the modulation of tumor cell proliferation (Ki67 labeling index) and gene expression associated with tamoxifen response in proliferation (BIRC5, MKI67, MYBL2, CCNB1, AURKA), cell cycle (UBE2C, PLK1, CEP55, CDK1, RRM2, TOP2A, PTTG1), cancer-associated stromal genes of invasion (FN1, SERPINH1, PLOD2, PDGFA, ITGAV) and extracellular matrix (COL11A1, SPP1, COMP, BGN). Within-participant changes between baseline and post-treatment were assessed using the Wilcoxon signed rank test. Differences between treatment arms were assessed using the Wilcoxon rank sum test and the Kruskal-Wallis test. Results: endoxifen-gel at both doses incurred no dermal or systemic toxicity nor change in circulating biomarkers (IGF1, SHBG) compared to placebo. All treated breasts contained endoxifen at each of five sampling locations; the median per-person tissue concentration in the treated participants was 0.6 ng/g (IQR 0.4-1.6), significantly higher (p &amp;lt; 0.001) than the median plasma concentration (0.2 ng/mL, IQR 0.2-0.2). The median ratio of the more potent (Z)-isomer to (E)-isomer at each breast location was 1.5 (IQR 0.96-2.54, p &amp;lt; 0.05). We observed non-significant overall reduction in tumor Ki67 LI (median change -1.7 with IQR -5.8, 3.6) and gene expression of MKI67 and the genes associated with proliferation, and cell cycle. However, downregulation of invasion signature genes (FN1, SERPINH1, PLOD2, PDGFA, ITGAV) was significant (p=0.03) and a cluster of six participants demonstrated a consistent reduction of MKI67 and multiple gene signatures suggesting the possibility that their tumors might be early responders to low endoxifen exposure within 3 to 4 weeks of treatment. Conclusions: our evaluation of transdermal (E/Z) endoxifen 10 and 20 mg in hydroalcoholic/oleic acid formulation demonstrates lack of early dermal toxicity, and good tolerability over a month or so of therapy. Our findings warrant development of transdermal formulations of (Z)-endoxifen with better dermal permeation for a Phase 2 breast cancer prevention trial compared to low-dose oral SERMs so that women at high-risk for breast cancer may have a range of cancer prevention options available to them. Citation Format: Oukseub Lee, Latifa Bazzi, Yanfei Xu, Erik Pearson, Minhua Wang, Omid Hosseini, Azza Akasha, Jennifer Choi, Masha Kocherginsky, Kelly Benante, Thomas Helland, Gunnar Mellgren, Eileen Dimond, Marjorie Perloff, Brandy Heckman-Stoddard, Seema Khan, Scott Karlan, Melissa Pilewskie. A randomized Phase I pre-operative window trial of transdermal endoxifen in women planning mastectomy: evaluation of dermal safety, intra-mammary drug distribution, and biologic effects [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr RF01-02.

Abstract PS10-03: Impact of Baseline Oestradiol and Testosterone on the Preventive Effect of Anastrozole

Abstract It is well known that serum levels of oestradiol and testosterone, esp free hormone levels, influence the risk of developing breast cancer in postmenopausal women (Thomas et al 1997, Hankinson et al 1998, Kaaks et al 2005, Tin Tin et al 2021). However very little is known about how these hormone levels influence the effectiveness of aromatase inhibitors. In the IBIS-II Prevention Trial we compared anastrozole to placebo in 3864 women at high risk of breast cancer (Cuzick et al 2020). Of these women 3644 (94.3%) had a baseline blood sample. In those with a valid blood sample, 72 in the anastrozole arm and 142 in the placebo arm developed breast cancer (including DCIS) after 12.9 years of follow up (OR = 0.49, 95% CI 0.37–0.66 P&amp;lt; 0.0001). For each case two controls were selected, matched on age, treatment arm and follow up longer than the matching case. In these women oestradiol (E2), testosterone (Testo) and SHBG were measured by liquid chromatography – tandem mass spectroscopy, and E2/SHBG and Testo/SHBG ratios were computed to approximate free hormone levels, and analysed in quartiles. Hormone replacement therapy was not allowed during the trial, and women with use within 3 months prior to entry or outlier hormone values were excluded from these analyses. In the placebo arm higher levels of both of these ratios were associated with a higher breast cancer rate (OR per quartile 1.25 (1.04-1.59), P=0.018) for E2/SHBG and (OR per quartile 1.22 (1.02-1.47), P = 0.032) for Testo/SHBG), whereas no significant effect was seen in the anastrozole arm (OR = 1.05 (0.81-1.37), and 1.16 (0.90-1.49), resp) (Table). Neither treatment interaction was significant. Absolute numbers of cases were similar between the anastrozole and placebo arms in the lowest quartile of E2/SHBG (18 anastrozole, 22 placebo), but higher numbers were seen in the placebo arm for the other quartiles. Similar results were seen for testo/SHBG, and supportive, but weaker results were seen for these two hormones without an SHBG adjustment, SHBG and BMI at entry. Adjusting for other risk factors had no influence on these findings. Effect sizes were similar during the 5 year treatment period and thereafter. There were too few ER negative cases to compare results by receptor status. Vasomotor side effects were higher with increasing E2/SHBG levels in both arms, but no other hormone showed an effect, and no hormone level was significantly associated with gynaecologic or musculoskeletal side effects. As aromatase inhibitors effectively eliminate the production of oestradiol in postmenopausal women, these results suggest they may be more effective in postmenopausal women with high oestradiol or testosterone levels, and raise questions about their value in women in the lower quartile of serum levels for these hormones for prevention and possibly adjuvant treatment. Table: Risk of breast cancer by quartiles of the oestradiol/SHBG in ratio high risk women treated with anastrozole or placebo. Citation Format: Jack Cuzick, Kim Chu, Brian Keevil, Antony Howell, Bernardo Bonanni, Evans Gareth, Kaija Holli, Sibylle Loibl, Nicholas Zdenkowski, Steven Cummings, Mitch Dowsett. Impact of Baseline Oestradiol and Testosterone on the Preventive Effect of Anastrozole [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS10-03.

Abstract PS07-01: Exemestane and breast cancer prevention: how low can we go? Drug and biomarker tissue levels in a randomized presurgical trial on exemestane alternative dosing regimen

Abstract Exemestane is an effective drug to reduce breast cancer risk reaching an overall 65% reduction in breast cancer in the placebo–controlled phase III MAP.3 trial. To improve its acceptability in primary prevention programs, we are seeking the minimal effective dose. In a 3-arm presurgical trial of 4-6 weeks before breast surgery in 180 postmenopausal women with ER-positive breast cancer, we investigated the activity of alternative exemestane schedules: 25 mg per day (QD), 25 mg three times/week (TIW) or 25 mg per week (QW) and showed that in adherent participants TIW was not inferior to QD in reducing circulating estradiol (Serrano et al JAMA Oncol. doi:10.1001/jamaoncol.2023.0089). Moreover, Ki67 reduction was seen in all arms with no significant difference among arms. Here, we analyzed the concentration of sex steroids, exemestane, and its main metabolite in the cancer and adjacent non-cancerous breast tissue. Tissues samples were homogenized before liquid-liquid extraction. After reconstitution, samples were analyzed by coupling liquid chromatography with tandem mass spectrometry (Sciex QTRAP 6500, Nexera system, Shimadzu). We obtained breast cancer tissue from 93 and non-cancerous breast tissue from 117 participants to measure exemestane, 17-OH-exemestane, and sex steroids. Exemestane and 17-OH-exemestane concentrations were detectable only in the QD arm, while in TIW and QW arms levels were below the Lower Limit of Detection (&amp;lt; LLD). Median exemestane level was 3807 fmol/g and 17485 fmol/g and median 17-OH-exemestane level was 338 fmol/g and 1343 fmol/g in cancer and non-cancerous tissue, respectively. Interestingly, drug and its metabolite accumulated 4-5-fold in non-cancerous tissue compared to cancer tissue in the QD arm. Despite the between-arm drug concentration difference, estradiol was almost completely suppressed in all arms in the non-cancerous tissue, attaining level &amp;lt; LLD in QD and TIW arms, and barely detectable in QW arm. The median in the QW arm was &amp;lt; LLD (&amp;lt; LLD, interquartile range &amp;lt; LLD, 25.5 fmol/g) showing no differences in QD vs TIW and QD vs QW (p = 0.364 and p = 0.693 respectively). While a dose-response trend was observed in cancer tissue, estradiol level was &amp;lt; LLD (&amp;lt; LLD,52.2 fmol/g) on QD, 17.1 (&amp;lt; LLD, 125.3) on TIW, and 128 (&amp;lt; LLD, 224.8) on QW (p=0.046 QD vs TIW arms). Estrone showed a clear dose response trend among arms, whereas no differences were observed for testosterone and androstenedione for both cancer and non-cancerous tissue in all arms. The Ki-67 change was analyzed in the previous paper; here we report the data for those patients who had drug and hormones tissue concentration measured, where Ki-67 decreased in all arms: median Ki67 change from baseline was QD -8 (-10, -3), TIW -6 (-11, -2), QW -4 (-8, -1). Conclusions: Exemestane 25 mg three times a week maintains comparable activity to the standard dose on tissue estradiol suppression and Ki67 decrease. Considering the estradiol suppression in non-cancerous tissue of the lowest exemestane dose, QW might even be considered for breast cancer risk reduction in primary prevention. Further analyses are ongoing to investigate the correlation with other biomarkers including the role of polymorphic UGT2B17 genotype that could identify candidates to lower exemestane dosage. Citation Format: Davide Serrano, Harriet Johansson, Bjørn-Erik Bertelsen, Gunnar Mellgren, Parijatham Thomas, Katherine Crew, Nagi B Kumar, Debora Macis, Valentina Aristarco, Aliana Guerrieri Gonzaga, Sara Gandini, Mauro D’Amico, Tania Buttiron Webber, Irene Maria Briata, Stefano Spinaci, Viviana Galimberti, Giuseppe Viale, Lana A. Vornik, Eduardo Villar-Sanchez, Powel Brown, Brandy M Heckman-Stoddard, Eva Szabo, Bernardo Bonanni, Andrea De Censi. Exemestane and breast cancer prevention: how low can we go? Drug and biomarker tissue levels in a randomized presurgical trial on exemestane alternative dosing regimen [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS07-01.

Abstract PO5-13-03: Early Detection of Breast Cancer using Targeted Plasma Metabolomic Profiling

Abstract Background: Breast cancer (BC) is the second leading cause of cancer death among women. Accordingly, early diagnosis is key to the successful treatment, management, and care of BC. Recent studies confirmed that plasma metabolites could be reliable cancer biomarkers, allowing for the development of a minimally invasive routine blood test that can be used for screening, as well as for monitoring disease evolution in patients. The exact metabolic pathways involved in early BC development remain unclear. Metabolomic profiling of women with BC may help to identify new biomarkers to predict breast cancer long before symptoms appear. The purpose of this study was to validate a plasma metabolomic biomarker panel for an improved risk assessment for early detection BC in 241 patients, and to understand the potential role and the relationship between BC subtypes and hormone receptor status. Methods: Our study included a total of 185 plasma samples from women with biopsy-confirmed BC and 56 plasma samples from healthy controls. A targeted, quantitative mass spectrometry (MS)-based metabolomics approach was used to analyze 138 metabolites in plasma samples using a combination of direct injection (DI) MS and reverse-phase high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). The sample set was split into a discovery set and validation set. Metabolite concentration data, clinical data, and hormones receptor status were used to determine optimal biomarker sets. The same biomarkers and regression models were used and assessed on the validation models. The area under the receiver operator characteristic curves (AUROC), sensitivities and specificities at selected cut off points were calculated for each subgroup. Results: A large proportion of BC patients were at an early stage, with 98 at stage I (53.0 %), 70 at stage II (37.8%), and 17 at stage III (9.2%). The BC patients were of all subtypes: 138 luminal A (76,2%), 23 luminal B (12.7%), 5 hormone receptor-negative/HER2-positive (2.8%), and 15 triples negative (8.3%). A feature selection was performed on the training set using Partial Least-Squares Discriminant Analysis (PLS-DA), and the top performing metabolites were identified as the most important in discriminating BC from healthy subjects. The impact of age was also investigated. Features with &amp;gt;80% missing values were removed. To predict BC, the best signature comprised 9 variables implicated in fatty acid metabolism, amino acid metabolism, polyamine biosynthesis and related signaling pathways We further developed and validated a logistic regression with AUROC &amp;gt; 0.9 using these metabolites and other clinical data for detecting different stages and subtypes of BC. Conclusion: This study identified and validated a simple, high-performing, metabolite-based test for the early detection of BC. After confirmation in other independent cohort studies, our findings could provide the foundations for the development of a blood-based routine test for women at the highest risk for BC that is cost-effective, accurate and reliable. In addition, this approach could be used to complement other modalities especially for BC patients with dense breasts. Citation Format: Jean-Francois Haince, Lun Zhang, Rashid Ahmed Bux, Paramjit S. Tappia, Bram Ramjiawan, David Wishart, Andrew Maksymiuk. Early Detection of Breast Cancer using Targeted Plasma Metabolomic Profiling [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-13-03.

A Novel RP-UHPLC-MS/MS Approach for the Determination of Tryptophan Metabolites Derivatized with 2-Bromo-4'-Nitroacetophenone.

Many biologically active metabolites of the essential amino acid L-tryptophan (Trp) are associated with different neurodegenerative diseases and neurological disorders. Precise and reliable methods for their determination are needed. Variability in their physicochemical properties makes the analytical process challenging. In this case, chemical modification of analyte derivatization could come into play. Here, we introduce a novel fast reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) coupled with tandem mass spectrometry (MS/MS) method for the determination of Trp and its ten metabolites in human plasma samples after derivatization with 2-bromo-4'-nitroacetophenone (BNAP). The derivatization procedure was optimized in terms of incubation time, temperature, concentration, and volume of the derivatization reagent. Method development comprises a choice of a suitable stationary phase, mobile phase composition, and gradient elution optimization. The developed method was validated according to the ICH guidelines. Results of all validation parameters were within the acceptance criteria of the guideline, i.e., intra- and inter-day precision (expressed as relative standard deviation; RSD) were in the range of 0.5-8.2% and 2.3-7.4%, accuracy was in the range of 93.3-109.7% and 94.7-110.1%, limits of detection (LODs) were in the range of 0.15-9.43 ng/mL, coefficients of determination (R2) were higher than 0.9906, and carryovers were, in all cases, less than 8.8%. The practicability of the method was evaluated using the blue applicability grade index (BAGI) with a score of 65. Finally, the developed method was used for the analysis of Alzheimer's disease and healthy control plasma to prove its applicability. Statistical analysis revealed significant changes in picolinic acid (PA), anthranilic acid (AA), 5 hydroxyindole-3-acetic acid (5-OH IAA), and quinolinic acid (QA) concentration levels. This could serve as the basis for future studies that will be conducted with a large cohort of patients.

A Workflow for Improved Analysis of Cross-Linking Mass Spectrometry Data Integrating Parallel Accumulation-Serial Fragmentation with MeroX and Skyline.

Cross-linking mass spectrometry (XL-MS) has evolved into a pivotal technique for probing protein interactions. This study describes the implementation of Parallel Accumulation-Serial Fragmentation (PASEF) on timsTOF instruments, enhancing the detection and analysis of protein interactions by XL-MS. Addressing the challenges in XL-MS, such as the interpretation of complex spectra, low abundant cross-linked peptides, and a data acquisition bias, our current study integrates a peptide-centric approach for the analysis of XL-MS data and presents the foundation for integrating data-independent acquisition (DIA) in XL-MS with a vendor-neutral and open-source platform. A novel workflow is described for processing data-dependent acquisition (DDA) of PASEF-derived information. For this, software by Bruker Daltonics is used, enabling the conversion of these data into a format that is compatible with MeroX and Skyline software tools. Our approach significantly improves the identification of cross-linked products from complex mixtures, allowing the XL-MS community to overcome current analytical limitations.