Circulating microRNAs as promising testicular translatable safety biomarkers: current state and future perspectives.

Drug-induced testicular injury (DITI) is one of the often-observed and challenging safety issues seen during drug development. Semen analysis and circulating hormones currently utilized have significant gaps in their ability to detect testicular damage accurately. In addition, no biomarkers enable a mechanistic understanding of the damage to the different regions of the testis, such as seminiferous tubules, Sertoli, and Leydig cells. MicroRNAs (miRNAs) are a class of non-coding RNAs that modulate gene expression post-transcriptionally and have been indicated to regulate a wide range of biological pathways. Circulating miRNAs can be measured in the body fluids due to tissue-specific cell injury/damage or toxicant exposure. Therefore, these circulating miRNAs have become attractive and promising non-invasive biomarkers for assessing drug-induced testicular injury, with several reports on their use as safety biomarkers for monitoring testicular damage in preclinical species. Leveraging emerging tools such as 'organs-on-chips' that can emulate the human organ's physiological environment and function is starting to enable biomarker discovery, validation, and clinical translation for regulatory qualification and implementation in drug development.

2021 White Paper on Recent Issues in Bioanalysis: Mass Spec of Proteins, Extracellular Vesicles, CRISPR, Chiral Assays, Oligos; Nanomedicines Bioanalysis; ICH M10 Section 7.1; Non-Liquid & Rare Matrices; Regulatory Inputs (Part 1A - Recommendations on Endogenous Compounds, Small Molecules, Complex Methods, Regulated Mass Spec of Large Molecules, Small Molecule, PoC & Part 1B - Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine).

The 15th edition of the Workshop on Recent Issues in Bioanalysis (15th WRIB) was held on 27 September to 1 October 2021. Even with a last-minute move from in-person to virtual, an overwhelmingly high number of nearly 900 professionals representing pharma and biotech companies, contract research organizations (CROs), and multiple regulatory agencies still eagerly convened to actively discuss the most current topics of interest in bioanalysis. The 15th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on biomarker assay development and validation (BAV) (focused on clarifying the confusion created by the increased use of the term "Context of Use - COU"); mass spectrometry of proteins (therapeutic, biomarker and transgene); state-of-the-art cytometry innovation and validation; and, critical reagent and positive control generation were the special features of the 15th edition. This 2021 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2021 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1A) covers the recommendations on Endogenous Compounds, Small Molecules, Complex Methods, Regulated Mass Spec of Large Molecules, Small Molecule, PoC. Part 1B covers the Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine. Part 2 (ISR for Biomarkers, Liquid Biopsies, Spectral Cytometry, Inhalation/Oral & Multispecific Biotherapeutics, Accuracy/LLOQ for Flow Cytometry) and Part 3 (TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparabil ity & Cut Point Appropriateness) are published in volume 14 of Bioanalysis, issues 10 and 11 (2022), respectively.

Identification of Appropriate Endogenous Biomarker for Risk Assessment of Multidrug and Toxin Extrusion Protein-Mediated Drug-Drug Interactions in Healthy Volunteers.

Endogenous biomarkers are emerging to advance clinical drug-drug interaction (DDI) risk assessment in drug development. Twelve healthy subjects received a multidrug and toxin exclusion protein (MATE) inhibitor (pyrimethamine, 10, 25, and 75 mg) in a crossover fashion to identify an appropriate endogenous biomarker to assess MATE1/2-K-mediated DDI in the kidneys. Metformin (500 mg) was also given as reference probe drug for MATE1/2-K. In addition to the previously reported endogenous biomarker candidates (creatinine and N1 -methylnicotinamide (1-NMN)), N1 -methyladenosine (m1 A) was included as novel biomarkers. 1-NMN and m1 A presented as superior MATE1/2-K biomarkers since changes in their renal clearance (CLr ) along with pyrimethamine dose were well-correlated with metformin CLr changes. The CLr of creatinine was reduced by pyrimethamine, however, its changes poorly correlated with metformin CLr changes. Nonlinear regression analysis (CLr vs. mean total concentration of pyrimethamine in plasma) yielded an estimate of the inhibition constant (Ki ) of pyrimethamine and the fraction of the clearance pathway sensitive to pyrimethamine. The in vivo Ki value thus obtained was further converted to unbound Ki using plasma unbound fraction of pyrimethamine, which was comparable to the in vitro Ki for MATE1 (1-NMN) and MATE2-K (1-NMN and m1 A). It is concluded that 1-NMN and m1 A CLr can be leveraged as quantitative MATE1/2-K biomarkers for DDI risk assessment in healthy volunteers.

Identification of Glycochenodeoxycholate 3-O-Glucuronide and Glycodeoxycholate 3-O-Glucuronide as Highly Sensitive and Specific OATP1B1 Biomarkers.

The aim of this study was to investigate the sensitivity and specificity of endogenous glycochenodeoxycholate and glycodeoxycholate 3-O-glucuronides (GCDCA-3G and GDCA-3G) as substrates for organic anion transporting polypeptide 1B1 (OATP1B1) in humans. We measured fasting levels of plasma GCDCA-3G and GDCA-3G using liquid chromatography-tandem mass spectrometry in 356 healthy volunteers. The mean plasma levels of both compounds were ~ 50% lower in women than in men (P = 2.25 × 10-18 and P = 4.73 × 10-9 ). In a microarray-based genome-wide association study, the SLCO1B1 rs4149056 (c.521T>C, p.Val174Ala) variation showed the strongest association with the plasma GCDCA-3G (P = 3.09 × 10-30 ) and GDCA-3G (P = 1.60 × 10-17 ) concentrations. The mean plasma concentration of GCDCA-3G was 9.2-fold (P = 8.77 × 10-31 ) and that of GDCA-3G was 6.4-fold (P = 2.45x10-13 ) higher in individuals with the SLCO1B1 c.521C/C genotype than in those with the c.521T/T genotype. No other variants showed independent genome-wide significant associations with GCDCA-3G or GDCA-3G. GCDCA-3G was highly efficacious in detecting the SLCO1B1 c.521C/C genotype with an area under the receiver operating characteristic curve of 0.996 (P < 0.0001). The sensitivity (98-99%) and specificity (100%) peaked at a cutoff value of 180 ng/mL for men and 90 ng/mL for women. In a haplotype-based analysis, SLCO1B1*5 and *15 were associated with reduced, and SLCO1B1*1B, *14, and *35 with increased OATP1B1 function. In vitro, both GCDCA-3G and GDCA-3G showed at least 6 times higher uptake by OATP1B1 than OATP1B3 or OATP2B1. These data indicate that the hepatic uptake of GCDCA-3G and GDCA-3G is predominantly mediated by OATP1B1. GCDCA-3G, in particular, is a highly sensitive and specific OATP1B1 biomarker in humans.

A Multiplexed HILIC-MS/HRMS Assay for the Assessment of Transporter Inhibition Biomarkers in Phase I Clinical Trials: Isobutyryl-Carnitine as an Organic Cation Transporter (OCT1) Biomarker.

There is a growing interest in using endogenous compounds as drug transporter biomarkers to facilitate drug-drug interaction (DDI) risk assessment in early phase I clinical trials. Compared to other drug transporters, however, no valid biomarker for hepatic organic cation transporter (OCT) 1 has been described to date. The present work represents the first report of an endogenous compound, isobutyryl-l-carnitine (IBC), as a potential clinical OCT1 biomarker for DDI assessment. A hydrophilic interaction chromatography (HILIC)-mass spectrometry/high resolution mass spectrometry (MS/HRMS) assay with a simple sample preparation method was developed. The assay is capable of simultaneously quantifying multiple endogenous compounds, including IBC, thiamine, N1-methylnicotinamide (1-NMN), creatinine, carnitine, and metformin, which is a probe for OCT1 and OCT2 and MATE1 and MATE2K (multidrug and toxin extrusion proteins) in clinical studies. The HRMS assay was fit-for-purpose validated in human plasma and demonstrated good linearity, accuracy, and precision for all analytes. It was further applied to two phase I clinical trials to evaluate potential biomarkers for OCT1 and additional cation transporters (renal OCT2, MATE1, and MATE2K). The clinical data demonstrated that plasma IBC changes correlated well with in vitro data and supported its use as a liver OCT1 biomarker. The described HILIC-MS/HRMS assay can be used as a "biomarker cocktail" to simultaneously assess clinical DDI risk for the inhibition of OCT1/2 and MATEs in clinical studies with new drug candidates.

Dose-Dependent Inhibition of OATP1B by Rifampicin in Healthy Volunteers: Comprehensive Evaluation of Candidate Biomarkers and OATP1B Probe Drugs.

To address the most appropriate endogenous biomarker for drug-drug interaction risk assessment, eight healthy subjects received an organic anion transporting polypeptide 1B (OATP1B) inhibitor (rifampicin, 150, 300, and 600 mg), and a probe drug cocktail (atorvastatin, pitavastatin, rosuvastatin, and valsartan). In addition to coproporphyrin I, a widely studied OATP1B biomarker, we identified at least 4 out of 28 compounds (direct bilirubin, glycochenodeoxycholate-3-glucuronide, glycochenodeoxycholate-3-sulfate, and hexadecanedioate) that presented good sensitivity and dynamic range in terms of the rifampicin dose-dependent change in area under the plasma concentration-time curve ratio (AUCR). Their suitability as OATP1B biomarkers was also supported by the good correlation of AUC0-24h between the endogenous compounds and the probe drugs, and by nonlinear regression analysis (AUCR-1 vs. rifampicin plasma Cmax (maximum total concentration in plasma)) to yield an estimate of the inhibition constant of rifampicin. These endogenous substrates can complement existing OATP1B-mediated drug-drug interaction risk assessment approaches based on agency guidelines in early clinical trials.

Evaluation of OptiFlow™-MS/MS for bioanalysis of pharmaceutical drugs and metabolites.

Aim: Microflow tandem mass spectrometry-based methods have been proposed as options to improve sensitivity and selectivity while improving sample utility and solvent consumption. Here, we evaluate a newly introduced microflow source, OptiFlow™, for quantitative performance. Results/methodology: We performed a comparison of the OptiFlow and IonDrive™ sources, respectively, on the same triple quadrupole mass spectrometer. The comparison used a neat cocktail of commercially available drugs and extracted plasma samples monitoring midazolam and alprazolam metabolites. Microflow produced a 2-4× signal increase for the neat drug cocktail and a 5-10× increase for extracted plasma samples. Conclusion: The OptiFlow method consistently gave increased signal response relative to the IonDrive method and enabled a better lower limit of quantitation for defining phamacokinetics.

2019 White Paper on Recent Issues in Bioanalysis: Chromatographic Assays (Part 1 - Innovation in Small Molecules and Oligonucleotides & Mass Spectrometric Method Development Strategies for Large Molecule Bioanalysis).

The 2019 13th Workshop on Recent Issues in Bioanalysis (WRIB) took place in New Orleans, LA, USA on April 1-5, 2019 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, week-long event - a full immersion week of bioanalysis, biomarkers, immunogenicity and gene therapy. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LCMS, hybrid LBA/LCMS, LBA cell-based/flow cytometry assays and qPCR approaches. This 2019 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2019 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations on Innovation in Small Molecules and Oligonucleotides & Mass Spec Method Development Strategies for Large Molecules Bioanalysis. Part 2 (2018 FDA BMV Guidance, 2019 ICH M10 BMV Draft Guideline and regulatory agencies' input on bioanalysis, biomarkers, immunogenicity and gene therapy) and Part 3 (New Insights in Biomarkers Assays Validation, Current & Effective Strategies for Critical Reagent Management, Flow Cytometry Validation in drug discovery & development & CLSI H62, Interpretation of the 2019 FDA Immunogenicity Guidance and The Gene Therapy Bioanalytical Challenges) are published in volume 11 of Bioanalysis, issues 23 and 24 (2019), respectively.

2018 White Paper on Recent Issues in Bioanalysis: 'A global bioanalytical community perspective on last decade of incurred samples reanalysis (ISR)' (Part 1 - small molecule regulated bioanalysis, small molecule biomarkers, peptides & oligonucleotide bioanalysis).

The 2018 12th Workshop on Recent Issues in Bioanalysis (12th WRIB) took place in Philadelphia, PA, USA on April 9-13, 2018 with an attendance of over 900 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day full immersion in bioanalysis, biomarkers and immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LC-MS, hybrid ligand binding assay (LBA)/LC-MS and LBA/cell-based assays approaches. This 2018 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2018 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for LC-MS for small molecules, peptides, oligonucleotides and small molecule biomarkers. Part 2 (hybrid LBA/LC-MS for biotherapeutics and regulatory agencies' inputs) and Part 3 (large molecule bioanalysis, biomarkers and immunogenicity using LBA and cell-based assays) are published in volume 10 of Bioanalysis, issues 23 and 24 (2018), respectively.

A fully automated and validated human plasma LC-MS/MS assay for endogenous OATP biomarkers coproporphyrin-I and coproporphyrin-III.

AIM: A validated LC-MS/MS assay for the quantitation of coproporphyrin-I and -III (CP-I, CP-III) in human plasma has been developed to understand the utility of both as possible endogenous biomarkers for organic anion-transporting polypeptides (OATP)-mediated drug-drug interactions (DDIs). MATERIALS AND METHODS:  Human plasma extracts were analyzed for CP-I and CP-III using a Sciex API 6500+ mass spectrometer. Results: The assay was utilized for plasma samples from a clinical DDI study involving a new chemical entity that presented as an OATP inhibitor in vitro. A formal DDI study, with a probe drug (atorvastatin), was also included as part of the clinical study. CONCLUSION: Changes in CP-I area under the plasma concentration versus time curve (AUC0-48 h) were observed, which were similar to the AUC ratio obtained with atorvastatin. These results support the idea that plasma CP-I may have utility in Phase I by supporting the rapid assessment of OATP inhibition risk.

HPLC-high-resolution mass spectrometry with polarity switching for increasing throughput of human in vitro cocktail drug-drug interaction assay.

AIM: Evaluation of HPLC-high-resolution mass spectrometry (HPLC-HRMS) full scan with polarity switching for increasing throughput of human in vitro cocktail drug-drug interaction assay. MATERIALS & METHODS: Microsomal incubates were analyzed using a high resolution and high mass accuracy Q-Exactive mass spectrometer to collect integrated qualitative and quantitative (qual/quant) data. RESULTS: Within assay, positive-to-negative polarity switching HPLC-HRMS method allowed quantification of eight and two probe compounds in the positive and negative ionization modes, respectively, while monitoring for LOR and its metabolites. CONCLUSION: LOR-inhibited CYP2C19 and showed higher activity for CYP2D6, CYP2E1 and CYP3A4. Overall, LC-HRMS-based nontargeted full scan quantitation allowed to improve the throughput of the in vitro cocktail drug-drug interaction assay.

A multiplex HRMS assay for quantifying selected human plasma bile acids as candidate OATP biomarkers.

AIM: Selected bile acids (BAs) in plasma have been proposed as endogenous probes for assessing drug-drug interactions involving hepatic drug transporters such as the organic anion-transporting polypeptides (OATP1B1 and OATP1B3). MATERIALS & METHODS: Plasma extracts were analyzed for selected BAs using a triple TOF API6600 high-resolution mass spectrometer. RESULTS: Glycodeoxycholic acid 3-sulfate, glycochenodeoxycholic acid 3-sulfate, glycodeoxycholic acid 3-O-ß-glucuronide and glycochenodeoxycholic acid 3-O-ß-glucuronide are presented as potential OATP1B1/3 biomarkers. CONCLUSION: Six BAs are quantified in human plasma using a multiplexed high-resolution mass spectrometry method. Glycodeoxycholic acid 3-sulfate and glycodeoxycholic acid 3-O-ß-glucuronide are proposed as potential biomarkers based on observed four- to fivefold increase in plasma AUC (vs placebo), following administration of a compound known to present as an OATP1B1/3 inhibitor in vitro.

LC-MS/MS assay for N1-methylnicotinamide in humans, an endogenous probe for renal transporters.

BACKGROUND: N1-methylnicotinamide (1-NMN) has been proposed as a potential clinical biomarker to assess drug-drug interactions involving organic cation transporters (OCT2) and multidrug and toxin extrusion protein transporters. RESULTS: A hydrophilic interaction liquid chromatography-MS/MS assay, to quantify 1-NMN, in human plasma and urine is reported. MATERIALS & METHODS: A hydrophilic interaction chromatography (HILIC)-tandem mass spectrometry (MS/MS) assay to quantify 1-NMN in human plasma and urine is reported. The basal 1-NMN levels in plasma and urine were 4-120 and 2000-15,000 ng/ml, respectively. CONCLUSION: 1-NMN plasma AUCs increased two- to fourfold versus placebo following the administration of a clinical candidate that in vitro experiments indicated was an OCT2 inhibitor. The described hydrophilic interaction liquid chromatography-MS/MS assay can be used to assess a clinical compound candidate for the inhibition of OCT2 and multidrug and toxin extrusion protein transporter in first-in-human studies.

2017 White Paper on recent issues in bioanalysis: aren't BMV guidance/guidelines 'Scientific'? (Part 1 - LCMS: small molecules, peptides and small molecule biomarkers).

The 2017 11th Workshop on Recent Issues in Bioanalysis (11th WRIB) took place in Los Angeles/Universal City, California from 3 April 2017 to 7 April 2017 with participation of close to 750 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, weeklong event - A Full Immersion Week of Bioanalysis, Biomarkers and Immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small and large molecule analysis involving LCMS, hybrid LBA/LCMS and ligand-binding assay (LBA) approaches. This 2017 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2017 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations for Small Molecules, Peptides and Small Molecule Biomarkers using LCMS. Part 2 (Biotherapeutics, Biomarkers and Immunogenicity Assays using Hybrid LBA/LCMS and Regulatory Agencies' Inputs) and Part 3 (LBA: Immunogenicity, Biomarkers and PK Assays) are published in volume 9 of Bioanalysis, issues 23 and 24 (2017), respectively.

A highly selective and sensitive LC-MS/HRMS assay for quantifying coproporphyrins as organic anion-transporting peptide biomarkers.

AIM: Coproporphyrin-I (CP-I) and coproporphyrin-III (CP-III) in plasma and urine have been proposed as biomarkers for assessing drug-drug interactions involving hepatic drug transporters such as organic anion-transporting peptides (OATP), 1B1 and 1B3. Materials & methods: Plasma and urine extracts were analyzed for CP-I/CP-III using a TripleTOF API6600 mass spectrometer. Results: Previously unreported, CP-I/CP-III doubly charged ions (m/z 328.14) were used as precursor ions to improve the assay sensitivity and selectivity over the singly charged precursor ions (m/z 655.28). Levels of CP-I and CP-III measured ranged 0.45-1.1 and 0.050-0.50 ng/ml in plasma and 5-35 and 1-35 ng/ml in urine, respectively. CONCLUSION: The described highly selective and sensitive CP-I/CP-III LC-HRMS assay offers options for earlier characterization and clinical safety projections for OATP1B1/3-mediated drug-drug interactions along with pharmacokinetic analyses of a new chemical entity as part of first-in-human clinical studies.

2016 White Paper on recent issues in bioanalysis: focus on biomarker assay validation (BAV) (Part 1 - small molecules, peptides and small molecule biomarkers by LCMS).

The 2016 10th Workshop on Recent Issues in Bioanalysis (10th WRIB) took place in Orlando, Florida with participation of close to 700 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations, and regulatory agencies worldwide. WRIB was once again a 5-day, weeklong event - A Full Immersion Week of Bioanalysis including Biomarkers and Immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small and large molecule analysis involving LCMS, hybrid LBA/LCMS, and LBA approaches, with the focus on biomarkers and immunogenicity. This 2016 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. This white paper is published in 3 parts due to length. This part (Part 1) discusses the recommendations for small molecules, peptides and small molecule biomarkers by LCMS. Part 2 (Hybrid LBA/LCMS and regulatory inputs from major global health authorities) and Part 3 (large molecule bioanalysis using LBA, biomarkers and immunogenicity) will be published in the Bioanalysis journal, issue 23.

Unconjugated payload quantification and DAR characterization of antibody-drug conjugates using high-resolution MS.

AIM: The application of high-resolution MS to antibody-drug conjugate (ADC) drug development may provide insight into their safety and efficacy. Quantification of unconjugated cytotoxic drug (payload) and characterization of drug-to-antibody ratio distribution were determined in plasma using orthogonal acceleration quadrupole-time-of-flight MS. RESULTS: Unconjugated payload quantification determined by quadrupole-time-of-flight-based MRM(highresolution) and triple quadrupole-based multiple reaction monitoring were comparable and achieved detection limits of 0.030 and 0.015 ng/ml, respectively. As determined by immunocapture and TOF-MS, drug-to-antibody ratio remained unchanged up to 3-weeks postdose for an ADC containing engineered glutamine linkers, but declined from four to three over 2 weeks in an ADC containing engineered cysteine linkers. CONCLUSION: The use of high-resolution MS in ADC drug discovery confirms its utility within the bioanalytical discipline.

Advances in high-resolution MS and hepatocyte models solve a long-standing metabolism challenge: the loratadine story.

BACKGROUND: Loratadine (LOR, Claritin(®)) is a long-acting antihistamine used to treat allergic rhinitis. The major active human metabolite, desloratadine (DL, Clarinex(®)), is extensively metabolized to 3-hydroxydesloratadine (3-OH-DL) (M40) and subsequently glucuronidated before elimination. This study revealed the ability of a novel, long-term hepatocyte micropatterned co-culture (MPCC) model to generate in vivo metabolites. Metabolites were detected and characterized using non-targeted MS/MS(ALL) with SWATH™ acquisition by a UHPLC-Q-TOF system. Results & methodology: Human MPCCs extensively metabolized LOR and formed 3-OH-DL-glucuronide (M13). Cross-species comparisons revealed monkey- and rat-specific metabolites with gender-specific DL-pyridine-N-oxide formation in male rats. These results demonstrate a first for an in vitro hepatocyte model to generate circulating metabolites of LOR and detect species-specific differences. Early focus on human metabolites could have spared characterization of nonhuman metabolites in preclinical species.