Endogenous Biomarkers Research Articles

Characterization of Renal OAT3 and Hepatic CYP3A Activities in Pregnant Women with Acute Pyelonephritis Using the Endogenous Biomarker Cortisol and 6β-Hydroxycortisol.

This study evaluates the impact of acute pyelonephritis in pregnant women on the in vivo activity of renal OAT3 using the endogenous biomarker (EB) 6β-hydroxycortisol (6β-OHF) renal clearance (CLrenal 6β-OHF) and AUC6β-OHF validated by correlating with the secretion clearance (CLsec) of the probe drug furosemide. Additionally, 6β-OHF formation clearance (CLformation 6β-OHF) as well as urinary (Ae6β-OHF/AeF) and plasma (AUC6βOHF/AUCF) ratios were also evaluated as EB for hepatic CYP3A activity. Pregnant women in their third trimester of gestation, diagnosed with acute pyelonephritis, were recruited before (pre-treatment, n = 8) and after (post-treatment, n = 8) cefuroxime treatment and resolution of acute pyelonephritis. All participants received a single dose of furosemide 40 mg for evaluation of OAT3 in vivo activity on both occasions followed by collection of urine and serial blood samples for 24 h. The CLrenal 6β-OHF (geometric mean and 95% CI) increased from 1.81 L/h (0.86-3.83) to 11.82 L/h (6.58-21.24), whereas the AUC6β-OHF decreased from 44.85 ng h/mL (30.96-64.98) to 24.20 ng h/mL (16.05-36.48) pre- and post-treatment. Significant statistical correlations were observed between furosemide CLsec and CLrenal 6β-OHF (R = 0.88, P =.01) and AUC6β-OHF (R = -0.66, P >.001). Additionally, the CLformation 6β-OHF was lower in pre-treatment 26.81 L/h (10.18-70.59) than in post-treatment 96.18 L/h (64.21-144.09), whereas AUC6βOHF/AUCF ratios were decreased from 0.014 (0.010-0.019) pre-treatment to 0.009 (0.006-0.013) post-treatment. Regarding Ae6β-OHF/AeF ratios, no differences were observed between pre-treatment and post-treatment. In conclusion, CLrenal 6β-OHF evaluates renal OAT3 activity when CYP3A is inhibited, whereas CLformation 6β-OHF evaluates hepatic CYP3A when OAT3 is inhibited, such as in pregnant women with acute pyelonephritis.

Chronic Kidney Disease: epidemiology, implications for clinical practice and equations for diagnosis

The article is based, among other things, on the updated KDIGO guideline for the evaluation and management of chronic kidney disease, which was published in Kidney International in March 2024. Chronic kidney disease is one of the most common chronic diseases, with a prevalence of around 10%, not least due to demographic ageing. The incidence of chronic kidney disease is approximately twice that of diabetes and approximately 20 times higher than that of cancer. Chronic kidney disease is classified using glomerular filtration rate and albuminuria. The definition of CKD may also include markers other than GFR and ACR. Patients with diabetes or hypertension should have GFR and ACR tested regularly. The individual risk of kidney failure requiring dialysis can be determined using a prediction equation. A better understanding of age- and gender-specific differences means that personalized therapy approaches are becoming increasingly important. Clinicians should be aware of the limitations of the endogenous biomarkers creatinine and cystatin C for determining GFR. For Germany, the equations of the European Kidney Function Consortium (EKFC) are recommended for estimating GFR.

In-depth mass-spectrometry reveals phospho-RAB12 as a blood biomarker of G2019S LRRK2-driven Parkinson's disease.

Leucine-rich repeat kinase 2 (LRRK2) inhibition is a promising disease-modifying therapy for LRRK2-associated Parkinson's disease (L2PD) and idiopathic PD (iPD). However, pharmaco-dynamic readouts and progression biomarkers for clinical trials aiming for disease modification are insufficient since no endogenous marker reflecting enhanced kinase activity of the most common LRRK2 G2019S mutation has been reported yet in L2PD patients. Employing phospho-/proteomic analyses we assessed the impact that LRRK2 activating mutations had in peripheral blood mononuclear cells (PBMCs) from a LRRK2 clinical cohort from Spain (n=174). The groups of study encompassed G2019S L2PD patients (n=37), non-manifesting LRRK2 mutation carriers of G2019S, here, G2019S L2NMCs (n=27), R1441G L2PD patients (n=14), R1441G L2NMCs (n=11), iPD patients (n=40), and healthy controls (n=45). We identified 207 differential proteins in G2019S L2PD compared to controls (39 up/168 down) and 67 in G2019S L2NMCs (10 up/57 down). G2019S down-regulated proteins affected the endolysosomal pathway, proteostasis, and mitochondria, e.g., ATIC, RAB9A, or LAMP1. At the phospho-proteome level, we observed increases in endogenous phosphorylation levels of pSer106 RAB12 in G2019S carriers, which were validated by immunoblotting after 1 year of follow-up (n=48). Freshly collected PBMCs from 3 G2019S L2PD, 1 R1441G L2PD, 1 iPD, and 5 controls (n=10) showed strong diminishment of pSer106 RAB12 phosphorylation levels after in-vitro administration of the MLi-2 LRRK2 inhibitor. Using machine learning, we identified an 18-feature G2019S phospho-/protein signature discriminating G2019S L2PD, L2NMCs, and controls with 96% accuracy that correlated with disease severity, i.e., UPDRS-III motor scoring. Using easily accessible PBMCs from a LRRK2 clinical cohort, we identified elevated levels of pSer106 RAB12 as an endogenous biomarker of G2019S carriers. Our data suggest that monitoring pSer106 RAB12 phosphorylation could be a relevant biomarker for tracking LRRK2 activation, particularly in G2019S carriers. Future work may determine whether pSer106 RAB12 could help with patient enrichment and monitoring drug efficacy in LRRK2 clinical trials.

Inhibition of OATP1B1/3 Rather Than UGT1A1 May Be the Major Cause of the Bilirubin Elevation After Atazanavir Administration.

Atazanavir has been reported to increase total serum bilirubin level up to ninefold. It is widely believed that the observed total bilirubin elevation is primarily due to UGT1A1 inhibition. However, UGT enzymes are well-known as a low-affinity and high-capacity system, and the observed drug-drug interaction mediated by UGTs is usually less than twofold. There were discrepancies in the explanation of total bilirubin elevation due to UGT1A1 inhibition alone, suggesting the contribution of other mechanism(s) to the interaction. As atazanavir is a potent OATP1B1/3 inhibitor and the hepatic uptake of both unconjugated and conjugated bilirubin are mediated by OATP1B1/3, these transporters could be involved in the bilirubin-atazanavir interaction. To better understand the roles of UGT1A1 and OATP1B1/3 in this interaction, it would be useful to characterize the contribution of each individual pathway to the interaction. As multiple compounds, pathways, and potentially UGT1A1 polymorphism are involved, a thorough physiologically-based pharmacokinetic (PBPK) analysis was utilized to integrate the information from various relevant in vitro and clinical studies to quantitatively estimate the contribution of UGT1A1 and OATP1B1/3 inhibition to the interaction between bilirubin and atazanavir. The PBPK analysis indicated that UGT1A1 inhibition plays a modest role in bilirubin and atazanavir interaction contributing less than 33%. The results also suggested that unconjugated bilirubin is less sensitive than raltegravir upon UGT1A1 inhibition, therefore, unconjugated bilirubin may not be a useful endogenous biomarker for UGT1A1 inhibition. The analysis demonstrated that the metabolism of unconjugated bilirubin shares common features of other UGT enzyme-mediated reactions.

Endogenous plasma riboflavin is not a viable BCRP biomarker in human.

Recent reports suggest that plasma riboflavin may serve as a biomarker for BCRP inhibition in humans. However, the clinical data supporting this claim have been limited, with only two studies showing modest increases in riboflavin levels after administration of a BCRP inhibitor. We have recently demonstrated that co-administration of 375 mg once daily (q.d.) cedirogant, an invitro BCRP inhibitor, significantly increased rosuvastatin (an OATP1B1/1B3 and BCRP substrate) exposures but did not change the levels of the OATP1B endogenous biomarker coproporphyrin-I, demonstrating that cedirogant is a clinical BCRP inhibitor. Samples from this same cedirogant clinical drug-drug interaction study were utilized to test the hypothesis that endogenous plasma riboflavin is a biomarker of BCRP inhibition. Plasma riboflavin levels in the absence of cedirogant ranged from 1 to 10 ng/mL across the 11 participants analyzed with minimal (<20%) intrasubject variability over a 24-hour interval. Contrary to expectations, 375 mg q.d. oral administration of cedirogant did not increase riboflavin levels. These data strongly suggest that endogenous plasma riboflavin is not a viable biomarker for BCRP inhibition in humans.

Ultra-Sensitive Quantification of Coproporphyrin-I and -III in Human Plasma Using Ultra-Performance Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry.

Organic anion transporting polypeptides (OATP) 1B1 and 1B3 are expressed in liver cells and are involved in drug uptake in the liver. OATP1B activity varies due to polymorphisms and is decreased by OATP1B inhibitors. Variability of OATP1B activity impacts the pharmacokinetics of OATP1B substrate drugs through drug-drug interactions. Lately, coproporphyrin-I (CP-I) and -III (CP-III) have been featured as quantitative endogenous biomarkers for evaluating the activity of OATP1B. CP-III has been reported to be transported not only by OATP1B but also by OATP2B1 in vitro. We have established a highly sensitive assay for the simultaneous measurement of CP-I and CP-III using a small volume of human plasma. The sample was pretreated by solid-phase extraction and analyzed by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). This method that uses 100 μL of plasma met the acceptance criteria of the US Food and Drug Administration guidance for bioanalytical method validation, and the lower limit of quantification was 0.01 ng/mL for both coproporphyrins. The clinical application of the method was evaluated by measuring plasma CP-I and CP-III concentrations in healthy volunteers and rheumatoid arthritis (RA) patients. The measured concentrations were within the calibration range (0.01-50 ng/mL). Using this novel method to measure plasma concentrations of CP-I and CP-III may contribute to the evaluation of the activities of OATP1B1, OATP1B3, and OATB2B1 in healthy individuals and patients with various clinical conditions including RA.

Effects of Cimetidine and Dolutegravir on the Endogenous Drug-Drug Interaction Biomarkers for Organic Cation Transporter 2 and Multidrug and Toxin Extrusion Protein 1 in Healthy Volunteers.

This study was designed to assess the quantitative performance of endogenous drug-drug interaction (DDI) biomarkers (N1-methylnicotinamide (1-NMN), N1-methyladenosine (m1A), and creatinine) for the organic cation transporters, OCT2 and MATE1/2K in the kidney. Ten healthy volunteers received cimetidine (400 and 800 mg, single dose) or dolutegravir (50 mg, twice a day) together with metformin (500 mg). Cimetidine and dolutegravir were considered to act mainly as MATE1/2K and OCT2 inhibitors, respectively. The renal clearance (CLr) of metformin was decreased by 15.5% and 42.5% by cimetidine 400 and 800 mg, and by 26.8% and 56.9% by dolutegravir first and fifth doses, respectively. CLr ratio (CLrR) of 1-NMN were 0.93 and 0.64 for cimetidine 400 and 800 mg, and 0.87 and 0.47 for dolutegravir first and fifth doses, respectively. CLrR of m1A was less than that of 1-NMN: 1.0 and 0.80 for cimetidine 400 and 800 mg, and 0.77 and 0.71 for dolutegravir first and fifth doses, respectively. CLr of creatinine was significantly decreased only by cimetidine 800 mg. Individual CLrR of 1-NMN and m1A showed a positive correlation with the corresponding CLrR of metformin with r2 of 0.58 and 0.55, respectively. When evaluated individually, m1A showed a better correlation during cimetidine periods (r2 0.64) than 1-NMN (r2 0.36), but vice versa during dolutegravir periods (r2 1-NMN, 0.80; m1A, 0.32). These results suggest that 1-NMN and m1A might be more promising than creatinine as endogenous biomarkers for quantitatively assessing the DDI potential of investigational drugs for OCT2 and MATE1/2K based on their CLrR change.

Hepatic Metabolic Enzyme Activity with Endogenous Substances-Current Status, Challenges and Limitations.

Precision dosing is essential in improving drug efficacy and minimizing adverse reactions, especially in liver impaired patients. However, there is no objective index to directly evaluate the body's ability to metabolize specific drugs. Many factors affect the activity of enzymes, and alter the systemic exposure of substrate drugs, like genetic polymorphism, drug-drug interactions and physiological/pathological state. So, quantifying the activities of enzymes dynamically would be helpful to make precision dosing. Recently, some endogenous substrates of enzymes, such as 6β-hydroxycortisol (6β-OH-cortisol)/cortisol and 6β-hydroxycortisone, have been identified to investigate variations in drug enzymes in humans. Clinical data obtained support their performance as surrogate probes in terms of reflecting the activities of corresponding enzyme. Therefore, a group of Monitored endogenous biomarkers in multiple points can address the uncertainty in drug metabolization in the preclinical phase and have the potential to fulfill precision dosing. This review focuses on recent progress in the contribution of endogenous substances to drug precision dosing, factors that influence enzyme activities, and drug exposure in vivo.

Abnormally high plasma concentrations of M-4, the active metabolite of edoxaban, at the onset of acute kidney injury in a patient receiving rifampin and clarithromycin: a case report

BackgroundEdoxaban, the only factor Xa inhibitor with active metabolites, is metabolized by carboxylesterase-1 to its main active metabolite, M-4, which is a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) and is excreted in bile and urine. Because the area under the plasma concentration–time curve ratio of M-4 to parent compound is typically less than 10% in healthy subjects, M-4 is generally considered to exhibit negligible antithrombotic activity in patients treated with edoxaban. However, we identified a case in which drug interactions and kidney impairment led to a substantive increase in plasma M-4 concentrations.Case presentationThis case report involved a 68-year-old man with pancreatic cancer who was orally administered edoxaban tablets for prevention of thrombus formation in non-valvular atrial fibrillation, in addition to rifampin and clarithromycin (CAM) for treatment of mycobacterium avium complex lung disease. These medications were temporarily discontinued for a pancreaticoduodenectomy but were resumed 8 days post-surgery (POD8). On POD9, the patient developed acute kidney injury, and the trough concentrations of edoxaban and M-4 were 131.1 ng/mL and 115.8 ng/mL, respectively (M-4 ratio: 88.3%). On POD11, the M-4 trough concentration and M-4 ratio increased to 216.2 ng/mL and 186.2%, respectively. The plasma concentration of coproporphyrin-I, an endogenous biomarker of OATP1B1 activity, increased during this period.ConclusionsThis case suggests that in patients with impaired renal function taking edoxaban, co-administration of carboxylesterase-1 inducers such as rifampin and/or OATP1B1 inhibitors such as rifampin or clarithromycin may increase plasma concentrations of M-4 to clinically non-negligible levels.

Lipid and Corticosteroid Biomarkers Under the Influence of Bisphosphonates.

Detecting the use of bisphosphonates (BPs) in equine athletes is of interest to regulators and laboratories due to the threat to welfare issues for the potential to provide analgesic effects and manipulating bone structure. The detection of BPs in biological matrices is challenging due to erratic biological elimination and inconsistent analytical recoveries. Therefore, complementary approaches are needed to provide evidence of their misuse in racehorses. BPs have two sub-classes: nitrogenous and non-nitrogenous. This study investigated plasma elimination following administration of one example from each sub-class, together with changes in endogenous eicosanoid and corticosteroids. Zoledronic acid (ZA) and tiludronic acid (TA) were administered by IV infusion to 8 thoroughbred horses with an 11-month washout period between each administration. Sample preparation for quantification of BPs by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilised a two-step solid phase extraction (SPE) consisting of polymeric reversed-phase followed by weak anion exchange prior to derivatisation using trimethyl orthoacetate. Endogenous biomarkers were analysed after protein precipitation and SPE with polymeric reversed-phase prior to liquid chromatography-high resolution mass spectrometry (LC-HRMS) using data independent acquisition. The LC-MS/MS analysis showed ZA was undetectable after 8 h post-administration while TA was detected up to the final collection point of 28 days post-administration. The LC-HRMS analysis utilised targeted (i.e., prior inclusion list of compounds) approaches to monitor level changes of eicosanoid and corticosteroid biomarkers. Putative biomarkers were identified and now subject to validation for translation into routine sample analysis for improved retrospectivity to detecting BP misuse in equine plasma.

Quantitative Prediction of Drug-Drug Interactions Caused by CYP3A Induction Using Endogenous Biomarker 4β-Hydroxycholesterol.

Evaluation of the CYP3A induction risk is important in early drug development stages. This study focused on 4β-hydroxycholesterol (4β-HC) as an endogenous biomarker of drug-drug interactions (DDIs) caused by CYP3A induction. We investigated a new approach using 4β-HC for quantitative prediction of DDIs caused by CYP3A induction based on the mechanistic static pharmacokinetic (MSPK) model. The induction ratio, i.e., the ratio of plasma 4β-HC or 4β-HC/cholesterol (4β-HC/C) with and without a coadministered CYP3A inducer, and the ratio of the area under the plasma concentration-time curve (AUCR), i.e., the ratio of the AUC of plasma CYP3A substrate drugs with and without a coadministered CYP3A inducer, were collected. The scaling factor (d) in the MSPK model was calculated from the induction ratio of 4β-HC or 4β-HC/C based on the systemic term in the MSPK model. The AUCR of 18 CYP3A substrates with and without coadministration of seven CYP3A inducers were then predicted by substituting the calculated d value into the MSPK model. This approach showed that approximately 84% of the predicted AUCR values were within a twofold range of the observed values, showing that this approach can be a good tool to quantitatively predict DDIs caused by CYP3A induction. SIGNIFICANCE STATEMENT: A concise approach to predict drug interactions with adequate accuracy is preferable in the early drug development stage. In this study, a new approach using 4β-hydroxycholesterol for quantitative prediction of drug-drug interactions caused by CYP3A induction was investigated. The predictability was verified using seven CYP3A inducers and 18 substrates.

Applications of the Cholesterol Metabolite, 4β-Hydroxycholesterol, as a Sensitive Endogenous Biomarker for Hepatic CYP3A Activity Evaluated within a PBPK Framework

Background/Objectives: Plasma levels of 4β-hydroxycholesterol (4β-OHC), a CYP3A-specific metabolite of cholesterol, are elevated after administration of CYP3A inducers like rifampicin and carbamazepine. To simulate such plasma 4β-OHC increase, we developed a physiologically based pharmacokinetic (PBPK) model of cholesterol and 4β-OHC in the Simcyp PBPK Simulator (Version 23, Certara UK Ltd.) using a middle-out approach. Methods: Relevant physicochemical properties and metabolic pathway data for CYP3A and CYP27A1 was incorporated in the model. Results: The PBPK model recovered the observed baseline plasma 4β-OHC levels in Caucasian, Japanese, and Korean populations. The model also captured the higher baseline 4β-OHC levels in females compared to males, indicative of sex-specific differences in CYP3A abundance. More importantly, the model recapitulated the increased 4β-OHC plasma levels after multiple-dose rifampicin treatment in six independent studies, indicative of hepatic CYP3A induction. The verified model also captured the altered 4β-OHC levels in CYP3A4/5 polymorphic populations and with other CYP3A inducers. The model is limited by scant data on relative contributions of CYP3A and CYP27A1 pathways and does not account for regulatory mechanisms that control plasma cholesterol and 4β-OHC levels. Conclusion: This study provides a quantitative fit-for-purpose and framed-for-future modelling framework for an endogenous biomarker to evaluate the DDI risk with hepatic CYP3A induction.

Utility of Biomarker-Informed Drug Interaction Evaluation in Drug Development and Regulatory Decision Making.

The measurement of endogenous biomarkers in plasma and urine before and after administration of an investigational drug in a clinical study may provide an early indication of its drug-drug interaction (DDI) potential via a specific pathway. In the first international harmonized guideline on drug interaction studies, the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) M12, endogenous biomarkers have been recognized as an emerging approach in the transporter- and enzyme-based DDI risk assessment. Clinical Pharmacology Roundtable Conference 2024 held at Pharmaceuticals and Medical Devices Agency (PMDA) brought together experts from regulatory agencies, academia, and industries to discuss potential advantages and challenges of the biomarkers approach in drug development and regulatory decision making. This meeting report facilitates stakeholders involved in drug development in better understanding the utility of biomarker approaches and promotes early implementation of biomarker-informed DDI evaluation in regulatory use.

Characterization and Prediction of Organic Anion Transporting Polypeptide 1B Activity in Prostate Cancer Patients on Abiraterone Acetate Using Endogenous Biomarker Coproporphyrin I.

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are important hepatic transporters. We previously identified OATP1B3 being critically implicated in the disposition of abiraterone. We aimed to further investigate the effects of abiraterone on the activities of OATP1B1 and OATP1B3 utilizing a validated endogenous biomarker coproporphyrin I (CP-I). We used OATP1B-transfected cells to characterize the inhibitory potential of abiraterone against OATP1B-mediated uptake of CP-I. Inhibition constant (K i) was incorporated into our physiologically based pharmacokinetic (PBPK) modeling to simulate the systemic exposures of CP-I among cancer populations receiving either our model-informed 500 mg or clinically approved 1000 mg abiraterone acetate (AA) dosage. Simulated data were compared with clinical CP-I concentrations determined among our nine metastatic prostate cancer patients receiving 500 mg AA treatment. Abiraterone inhibited OATP1B3-mediated, but not OATP1B1-mediated, uptake of CP-I in vitro, with an estimated K i of 3.93 μM. Baseline CP-I concentrations were simulated to be 0.81 ± 0.26 ng/ml and determined to be 0.72 ± 0.16 ng/ml among metastatic prostate cancer patients, both of which were higher than those observed for healthy subjects. PBPK simulations revealed an absence of OATP1B3-mediated interaction between abiraterone and CP-I. Our clinical observations confirmed that CP-I concentrations remained comparable to baseline levels up to 12 weeks post 500 mg AA treatment. Using CP-I as an endogenous biomarker, we identified the inhibition of abiraterone on OATP1B3 but not OATP1B1 in vitro, which was predicted and observed to be clinically insignificant. We concluded that the interaction risk between AA and substrates of OATP1Bs is low. SIGNIFICANCE STATEMENT: The authors used the endogenous biomarker coproporphyrin I (CP-I) and identified abiraterone as a moderate inhibitor of organic anion transporting polypeptide (OATP) 1B3 in vitro. Subsequent physiologically based pharmacokinetic (PBPK) simulations and clinical observations suggested an absence of OATP1B-mediated interaction between abiraterone and CP-I among prostate cancer patients. This multipronged study concluded that the interaction risk between abiraterone acetate and substrates of OATP1Bs is low, demonstrating the application of PBPK-CP-I modeling in predicting OATP1B-mediated interaction implicating abiraterone.

Identification of protein biomarkers in wastewater linked to the incidence of COVID-19

Wastewater-based epidemiological (WBE) surveillance is a viable disease surveillance technique capable of monitoring the spread of infectious disease agents in sewershed communities. In addition to detecting viral genomes in wastewater, WBE surveillance can identify other endogenous biomarkers that are significantly elevated and excreted in the saliva, urine, and/or stool of infected individuals. Human protein biomarkers allow the realization of real-time WBE surveillance using highly sensitive biosensors. In this study, we analyzed endogenous protein biomarkers present in wastewater influent through liquid chromatography–tandem mass spectrophotometry and scaffold data-independent acquisition to identify candidate target protein biomarkers for WBE surveillance of SARS-CoV-2. We found that out of the 1382 proteins observed in the wastewater samples, 44 were human proteins associated with infectious diseases. These included immune response substances such as immunoglobulins, cytokine–chemokines, and complements, as well as proteins belonging to antimicrobial and antiviral groups. A significant correlation was observed between the intensity of human infectious disease-related protein biomarkers in wastewater and COVID-19 case numbers. Real-time WBE surveillance using biosensors targeting immune response proteins, such as antibodies or immunoglobulins, in wastewater holds promise for expediting the implementation of relevant policies for the effective prevention of infectious diseases in the near future.

Analysis of human biological samples using porous graphitic carbon columns and liquid chromatography-mass spectrometry: a review.

Liquid chromatography-mass spectrometry (LC-MS) has emerged as a powerful analytical technique for analyzing complex biological samples. Among various chromatographic stationary phases, porous graphitic carbon (PGC) columns have attracted significant attention due to their unique properties-such as the ability to separate both polar and non-polar compounds and their stability through all pH ranges and to high temperatures-besides the compatibility with LC-MS. This review discusses the applicability of PGC for SPE and separation in LC-MS-based analyses of human biological samples, highlighting the diverse applications of PGC-LC-MS in analyzing endogenous metabolites, pharmaceuticals, and biomarkers, such as glycans, proteins, oligosaccharides, sugar phosphates, and nucleotides. Additionally, the fundamental principles underlying PGC column chemistry and its advantages, challenges, and advances in method development are explored. This comprehensive review aims to provide researchers and practitioners with a valuable resource for understanding the capabilities and limitations of PGC columns in LC-MS-based analysis of human biological samples, thereby facilitating advancements in analytical methodologies and biomedical research.

New Biomarkers for Renal Transporter-Mediated Drug-Drug Interactions: Metabolomic Effects of Cimetidine, Probenecid, Verapamil, and Rifampin in Humans.

The inhibition of renal transport proteins organic cation transporter 2 (OCT2), multidrug and toxin extrusion proteins (MATE1, MATE2-K), and organic anion transporters (OAT1, OAT3) causes clinically relevant drug-drug interactions (DDI). Endogenous biomarkers could be used to improve risk prediction of such renal DDIs. While a number of biomarkers for renal DDIs have been described so far, multiple criteria for valid biomarkers have frequently not been investigated, for example, specificity, metabolism, or food effects. Therefore, there is a need for novel biomarkers of renal DDIs. Here, we investigated the global metabolomic effects following the administration of two classical inhibitors of renal transport proteins [cimetidine (OCT2/MATEs), probenecid (OATs)] in human plasma and urine of healthy volunteers. Additionally, we investigated metabolomic effects of two inhibitors of other transporters [verapamil (P-glycoprotein), rifampin (organic anion transporting polypeptides)] as controls. This analysis shows that both cimetidine and probenecid affect compounds involved in caffeine metabolism, carnitines, and sulfates. Hierarchical cluster analysis of the effects of all four inhibitors on endogenous compounds identified multiple promising new sensitive and specific biomarker candidates for OCT2/MATE- or OAT-mediated DDIs. For OCT2/MATEs, 5-amino valeric acid betaine (median log2-fold change of estimated renal elimination: -3.62) presented itself as a promising candidate. For OATs, estimated renal elimination of 7-methyluric acid and cinnamoylglycine (median log2-fold changes -3.10 and -1.92, respectively) was both sensitive and specific. This study provides comprehensive information on metabolomic effects of transport protein inhibition in humans and identifies putative new sensitive and specific biomarkers for renal transporter-mediated DDIs.

Coproporphyrin-I as a Selective OATP1B Biomarker Can Be Used to Delineate the Mechanisms of Complex Drug-Drug Interactions: Cedirogant Case Study.

Cedirogant is an inverse agonist of retinoic acid-related orphan receptor gamma thymus developed for the treatment of chronic plaque psoriasis. Cedirogant induces cytochrome P450 (CYP) 3A4 while inhibiting P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1, and OATP1B3 in vitro. Static drug-drug interactions (DDIs) predictions suggested possible clinical induction of CYP3A4, and inhibition of P-gp, BCRP, and OATP1B1, leading to challenges in interpreting DDI studies between cedirogant and substrates of CYP3A, P-gp, BCRP, and OATP1B1/3. Here the effects of cedirogant on the pharmacokinetics of two statin drugs were investigated in healthy participants. Coproporphyrin-I (CP-I), a selective endogenous OATP1B biomarker, was used to assess the impact of cedirogant on OATP1B. Cedirogant (375 mg once daily) increased rosuvastatin maximum plasma concentration (Cmax) and area under the plasma concentration curve (AUCtau) by 141% and 55%, respectively when co-administered, whereas atorvastatin Cmax increased by 40% with no effect on its AUCtau compared with administration of rosuvastatin/atorvastatin alone. Cedirogant did not increase CP-I exposures, indicating no clinical OATP1B inhibition. The increased rosuvastatin exposure and minimal change in atorvastatin exposure with co-administration of cedirogant is attributed to BCRP inhibition and interplay between P-gp/BCRP inhibition and CYP3A induction, respectively. Correlation analysis with data from two investigational drugs (glecaprevir and flubentylosin) demonstrated that OATP1B1 R-value of > 1.5 and [Cmax,u]/[OATP1B1 IC50] of > 0.1 are associated with > 1.25-fold increase in CP-I Cmax ratio. This demonstrates the utility of CP-I in disentangling mechanisms underlying a complex DDI involving multiple transporters and enzymes and proposes refined criteria for static OATP1B inhibition predictions.

Relevance of plasma lenvatinib concentrations and endogenous urinary cytochrome P450 3A activity biomarkers in clinical practice.

Lenvatinib (LEN), a multitarget tyrosine kinase inhibitor used in various cancer treatments, is mainly metabolized by cytochrome P450 3A (CYP3A) enzymes. The importance of therapeutic drug monitoring (TDM) in patients administered LEN has been proposed. Although some biomarkers of endogenous CYP3A activity have been reported, their utility in dosage adjustments has not been well evaluated. This study investigated the correlation between plasma LEN concentrations and endogenous urinary CYP3A biomarkers in clinical practice. Concentrations of plasma LEN (N = 225) and CYP3A biomarkers (cortisol, 6β-hydroxycortisol, deoxycholic acid, and 1β-hydroxydeoxycholic acid) in urine (N = 214) from 20 patients (hepatocellular carcinoma, N = 6; thyroid cancer, N = 3; endometrial cancer, N = 8; and renal cell carcinoma, N = 3) collected for consultation for up to 1 year were evaluated using liquid chromatography-tandem mass spectrometry. Moreover, plasma trough LEN concentrations were predicted using a three-compartment model with linear elimination for outpatients administered LEN before sample collection. Moderate correlations were observed between the quantified actual concentrations and the predicted trough concentrations of LEN, whereas there was no correlation with endogenous urinary CYP3A biomarkers. The utility of endogenous urinary CYP3A biomarkers could not be determined. However, TDM for outpatients administered orally available medicines may be predicted using a nonlinear mixed effect model (NONMEM). This study investigated the utility of endogenous urinary CYP3A biomarkers for personalized medicine and NONMEM for predicting plasma trough drug concentrations. These findings will provide important information for further clinical investigation and detailed TDM.

An assessment of the antihyperlipidemic ingredients of Qi Ge Decoction based on metabolomics combined with serum pharmacochemistry.

This study aims to explore the pharmacological substance basis of Qi Ge Decoction (QG) in antihyperlipidemia through a combination of metabolomics and serum pharmacochemistry. We used ultra-performance liquid chromatography quadrupole-time-of-flight/MS (UPLC Q-TOF/MS) to analyze and identify the chemical constituents of QG in vitro and in blood chemical components. The metabolomics technology was used to analyze serum biomarkers of QG in preventing and treating hyperlipidemia. We constructed a mathematical model of the relationship between constituents absorbed into the blood and endogenous biomarkers and explored the potential therapeutic application of QG for the prevention and treatment of hyperlipidemia. Compared with the model group, the levels of total cholesterol and triglyceride in the QG group were significantly decreased (P < 0.01). A total of 12 chemical components absorbed into the blood were identified, and 48 biomarkers of the hyperlipidemia model were obtained from serum metabolomic analysis, of which 15 metabolites were backregulated after QG intervention. Puerarin, hesperetin, puerarin xyloside, calycosin, and monohydroxy-tetramethoxyflavone had a high correlation with the biomarkers regulated by QG. This study elucidated the material basis of QG in the intervention of hyperlipidemia, thereby facilitating future research aimed at further revealing the pharmacodynamic material basis of QG's antihyperlipidemic effects.