Monkey Hepatocytes Research Articles

The Comparative Metabolism of a Novel Hepatocellular Carcinoma Therapeutic Agent, 2,3-Diamino-N-(4-(benzo[d]thiazol-2-yl)phenyl)propanamide, in Human and Animal Hepatocytes.

[2,3-diamino-N-(4-(benzo[d]thiazol-2-yl)phenyl)propanamide], named as ETN101, is a novel therapeutic agent for hepatocellular carcinoma. In vitro studies examined ETN101 metabolites in human, mouse, rat, dog, and monkey hepatocytes and identified the drug-metabolizing enzymes involved using cDNA-expressed human recombinant cytochrome P450s (CYPs), carboxylesterases (CESs), N-acetyltransferase (NAT) 1, and human liver cytosol. ETN101 showed similar metabolic stability across hepatocytes from five species, with particularly comparable stability in humans, rats, and monkeys. Its half-life was 75.0 min in humans, 68.9 in rats, 73.1 in monkeys, 120.4 in mice, and 112.7 in dogs. Thirty-four ETN101 metabolites, including the major metabolite M1, were identified using liquid chromatography-high-resolution mass spectrometry. ETN101 was primarily metabolized to M1 and CYP1A2 is exclusively responsible for M1 metabolism. Both NAT1 and NAT2 were responsible for the N-acetylation of M1 to M2. ETN101 remained stable in human CESs. In conclusion, this study provides comprehensive insights into the metabolic characteristics of ETN101, valuable for its toxicological and clinical development.

Mechanistic Determinants of Daprodustat Drug-Drug Interactions and Pharmacokinetics in Hepatic Dysfunction and Chronic Kidney Disease: Significance of OATP1B-CYP2C8 Interplay.

Daprodustat is the first oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved recently for the treatment of anemia caused by chronic kidney disease (CKD) in adults receiving dialysis. We evaluated the role of organic anion transporting polypeptide (OATP)1B-mediated hepatic uptake transport in the pharmacokinetics (PKs) of daprodustat using in vitro and in vivo studies, and physiologically-based PK (PBPK) modeling of its drug-drug interactions (DDIs) with inhibitor drugs. In vitro, daprodustat showed specific transport by OATP1B1/1B3 in the transfected cell systems and primary human and monkey hepatocytes. A single-dose oral rifampin (OATP1B inhibitor) reduced daprodustat intravenous clearance by a notable9.9 ± 1.2-fold (P < 0.05) in cynomolgus monkeys. Correspondingly, volume of distribution at steady-state was also reduced by 5.0 ± 1.1-fold, whereas the half-life change was minimal (1.5-fold), corroborating daprodustat hepatic uptake inhibition by rifampin. A PBPK model accounting for OATP1B-CYP2C8 interplay was developed, which well described daprodustat PK and DDIs with gemfibrozil (CYP2C8 and OATP1B inhibitor) and trimethoprim (weak CYP2C8 inhibitor) within 25% error of the observed data in healthy subjects. About 18-fold increase in daprodustat area under the curve (AUC) following gemfibrozil treatment was found to be associated with strong CYP2C8 inhibition and moderate OATP1B inhibition. Moreover, PK modulation in hepatic dysfunction and subjects with CKD, in comparison to healthy control, was well-captured by the model. CYP2C8 and/or OATP1B inhibitor drugs (e.g., gemfibrozil, clopidogrel, rifampin, and cyclosporine) were predicted to perpetrate moderate-to-strong DDIs in healthy subjects, as well as, in target CKD population. Daprodustat can be used as a sensitive CYP2C8 index substrate in the absence of OATP1B modulation.

In Vitro Pharmacokinetic Behavior of Antiviral 3-Amidinophenylalanine Derivatives in Rat, Dog and Monkey Hepatocytes

Type II transmembrane serine proteases represent pharmacological targets for blocking entry and spread of influenza or coronaviruses. In this study, the depletion rates of the 3-amidinophenylalanine (3-APhA)-derived matriptase/TMPRSS2 inhibitors MI-463, MI-472, MI-485 or MI-1900 were determined by LC-MS/MS measurements over a period of 300 min using suspensions of rat, dog and cynomolgus monkey primary hepatocytes. From these in vitro pharmacokinetic (PK) experiments, intrinsic clearance values (Clint) were evaluated, and in vivo pharmacokinetic parameters (hepatic clearance, hepatic extraction ratio and bioavailability) were predicted. It was found that rat hepatocytes were the most active in the metabolism of 3-APhA derivatives (Clint 31.9-37.8 mL/min/kg), whereas dog and monkey cells displayed somewhat lower clearance of these compounds (Clint 6.6-26.7 mL/min/kg). These data support elucidation of important PK properties of anti-TMPRSS2/anti-matriptase 3-APhAs using mammalian hepatocyte models and thus contribute to the optimization of lead compounds.

Identification and characterization of the metabolites of moscatilin in mouse, rat, dog, monkey and human hepatocytes by LC-Orbitrap-MS/MS combined with diagnostic fragment ions and accurate mass measurements.

Moscatilin, a bibenzyl derivative from the stem of Dendrobium loddigesii, has been shown to have anticancer activity. The aim of this study was to identify and characterize the possible in vitro metabolites of moscatilin generated from hepatocytes. The metabolites generated in the hepatocytes of mouse, rat, dog, monkey and human were identified and characterized employing ultra-high-performance liquid chromatography coupled with quadrupole Orbitrap tandem mass spectrometry (LC-Orbitrap-MS/MS) based on diagnostic fragment ions and accurate mass measurements. A total of 18 metabolites were identified, among which seven were phase I and 11 were phase II metabolites. The plausible structures of the metabolites and the probable biotransformation pathways were proposed based on the diagnostic fragment ions, chemical formula and mass fragmentation pattern, as well as the accurate masses. The majority of phase I metabolites were generated by demethylation and hydroxylation, while phase II metabolites were mainly generated by glucuronidation, glutathione conjugation and sulfation. Our study first expounded the metabolites of moscatilin in mouse, rat, dog, monkey and human hepatocytes and provided a foundation for a further pharmacokinetic and toxicity study. More importantly, LC-Orbitrap-MS/MS combined with diagnostic fragment ions and accurate mass measurements has been proved to be an effective method for the rapid identification of bibenzyl derivatives and their metabolites.

In vitro metabolism, pharmacokinetics and drug interaction potentials of emvododstat, a DHODH inhibitor

Emvododstat was identified as a potent inhibitor of dihydroorotate dehydrogenase and is now in clinical development for the treatment of acute myeloid leukaemia and COVID-19. The objective of this paper is to evaluate the metabolism, pharmacokinetics, and drug interaction potentials of emvododstat. Emvododstat showed high binding to plasma protein with minimal distribution into blood cells in mouse, rat, dog, monkey, and human whole blood. O-Demethylation followed by glucuronidation appeared to be the major metabolic pathway in rat, dog, monkey, and human hepatocytes. CYP2C8, 2C19, 2D6, and 3A4 were involved in O-desmethyl emvododstat metabolite formation. Both emvododstat and O-desmethyl emvododstat inhibited CYP2D6 activity and induced CYP expression to different extents in vitro. Emvododstat and O-desmethyl emvododstat inhibited BCRP transporter activity but did not inhibit bile salt transporters and other efflux or uptake transporters. Neither emvododstat nor O-desmethyl emvododstat was a substrate for common efflux or uptake transporters investigated. Emvododstat is bioavailable in mice, rats, dogs, and monkeys following a single oral dose. The absorption was generally slow with the mean plasma Tmax ranging from 2 to 5 h; plasma exposure of O-desmethyl emvododstat was lower in rodents, but relatively higher in dogs and monkeys.

Azelaic Acid Esters as Pluripotent Immunomodulatory Molecules: Nutritional Supplements or Drugs

Azelaic acid and its esters, the azelates, occur naturally in organisms ranging from plants to humans. We have shown that diethyl azelate (DEA) exhibits a broad range of immunomodulatory activities in vitro and in vivo, and mitigates insulin resistance. To further investigate the therapeutic utility of DEA, we evaluated its mutagenicity in Salmonella typhimurium strains, examined metabolism of DEA in rat, dog, monkey and human primary hepatocytes and in human saliva, determined pharmacokinetics of DEA after an oral dose in rats, and queried its physicochemical properties for drug-like characteristics. DEA was not mutagenic in bacterial strains ± rat liver metabolic activation system S-9. It was chemically unstable in hepatocyte culture medium with a half-life of &lt;1 h and was depleted by the hepatocytes in &lt;5 min, suggesting rapid hepatic metabolism. DEA was also quickly degraded by human saliva in vitro. After an oral administration of DEA to rats, the di- and monoester were undetectable in plasma while the levels of azelaic acid increased over time, reached maximum at &lt;2 h, and declined rapidly thereafter. The observed pharmacological properties of DEA suggest that it has value both as a drug or a nutritional supplement.

More than the half number of the severe CAD patients without features of metabolic syndrome had hyperlipoprotein(a)-emia

Abstract Background It was reported that insulin suppresses apolipoprotein(a) synthesis in primary cultures of cynomolgus monkey hepatocytes (Neele DM. Diabetologia 1999). Therefore, there is a possibility that inverse association exists between lipoprotein(a); Lp(a) and metabolic syndrome (Mets) with insulin resistance/ hyperinsulinemia for the coronary atherosclerosis. Purpose The purpose is to examine the association between Lp(a) and Mets on the CAD patients. Method 847 male subjects with angiographically demonstrated CAD were enrolled. The subjects were divided into the five groups according to the scored numbers by the counting of Mets components shown below (presence 1, absence 0); 1. BMI ≥25kg/m2, 2. comorbidity of hypertension, 3. triglyceride ≥150mg/dL and/or HDL cholesterol &amp;lt;40mg/dL, 4. fasting plasma glucose ≥110mg/dL and/or comorbidity of diabetes mellitus (Group 0; without any Mets components, Group 4; with all Mets component). The insulin levels (μU/mL) and the prevalence of hyperLp(a)-emia (≥30 mg/dL) were compared between in Group 0 and in Group 4. The blood samples for laboratory tests were collected after an over night fast. Result As the scored numbers increased, the insulin levels increased (Group 0; 5.1 μU/mL versus Group 4; 11.4 μU/mL: p&amp;lt;0.0001) and the prevalence of hyperlipoprotein(a)-emia decreased (Group 0; 41.6% versus Group 4; 21.4%: p&amp;lt;0.01). The prevalence of hyperLp(a)-emia increased as the severity of coronary atherosclerosis aggravated (Figure 1; one vessel disease 21.5%, two vessel disease 27.0% three vessel disease 32.1%: one vessel disease versus three vessel disease p&amp;lt;0.01). Especially to limited the three vessel disease subjects (Figure 2), the prevalence of hyperlipoprotein(a)-emia in Group 0 was markedly high (56.7%). Conclusion More than the half number of severe CAD patients without features of Mets had hyperLp(a)-emia. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Application of a PBPK model to elucidate the changes of systemic and liver exposures for rosuvastatin, carotegrast, and bromfenac followed by OATP inhibition in monkeys.

The impact of organic anion‐transporting polypeptide (OATP) inhibition on systemic and liver exposures of three OATP substrates was investigated in cynomolgus monkeys. A monkey physiologically‐based pharmacokinetic (PBPK) model was constructed to describe the exposure changes followed by OATP functional attenuation. Rosuvastatin, bromfenac, and carotegrast were administered as a single intravenous cassette dose (0.5 mg/kg each) in monkeys with and without predosing with rifampin (RIF; 20 mg/kg) orally. The plasma exposure of rosuvastatin, bromfenac, carotegrast, and OATP biomarkers, coproporphyrin I (CP‐I) and CP‐III were increased 2.3, 2.1, 9.1, 5.4, and 8.8‐fold, respectively, when compared to the vehicle group. The liver to plasma ratios of rosuvastatin and bromfenac were reduced but the liver concentration of the drugs remained unchanged by RIF treatment. The liver concentrations of carotegrast, CP‐I, and CP‐III were unchanged at 1 h but increased at 6 h in the RIF‐treated group. The passive permeability, active uptake, and biliary excretion were characterized in suspended and sandwich‐cultured monkey hepatocytes and then incorporated into the monkey PBPK model. As demonstrated by the PBPK model, the plasma exposure is increased through OATP inhibition while liver exposure is maintained by passive permeability driven from an elevated plasma level. Liver exposure is sensitive to the changes of metabolism and biliary clearances. The model further suggested the involvement of additional mechanisms for hepatic uptakes of rosuvastatin and bromfenac, and of the inhibition of biliary excretion for carotegrast, CP‐I, and CP‐III by RIF. Collectively, impaired OATP function would not reduce the liver exposure of its substrates in monkeys.

Albumin-Mediated Uptake Improves Human Clearance Prediction for Hepatic Uptake Transporter Substrates Aiding a Mechanistic In Vitro-In Vivo Extrapolation (IVIVE) Strategy in Discovery Research.

This study focused on exploring various in vitro to in vivo extrapolation (IVIVE) approaches with the primary goal of improving human hepatic clearance (CL) prediction for OATP substrates. To that effect, the impact of albumin-mediated uptake in human hepatocytes was investigated. In vitro hepatic uptake assay using suspended human hepatocytes was performed with 16 selected OATP substrates to determine the uptake CL in the absence and presence of 4% BSA and unbound hepatocyte to media partition coefficient (Kpuu). Substantial enhancement of the unbound uptake CL (PSu,inf) was observed in the presence of 4% BSA, demonstrating "albumin-mediated" uptake. Prediction of human hepatic CL was performed using two non-traditional IVIVE approaches: initial uptake CL (PSu,inf) and intrinsic metabolic CL (CLint,met) corrected by Kpuu based on extended clearance concept. Compared to traditional IVIVE using CLint,met only, the two tested IVIVE approaches significantly improved the prediction of human hepatic CL. Particularly, direct extrapolation from PSu,inf (+BSA) showed the most robust correlation with in vivo human hepatic CL for all 16 compounds with bias of 1.9-2.0 for two lots of human hepatocytes, respectively. In addition, PSu,inf (+BSA) and Kpuu were also determined in suspended cynomolgus monkey hepatocytes. Prediction of monkey hepatic CL was improved by both approaches, although with more bias compared to human. These results suggested supplementing 4% BSA in human hepatocyte uptake assay provides a useful tool to characterize hepatic uptake CL for OATP substrates, enabling more accurate human CL prediction without any empirical scaling factor (ESF).

The inverse association between lipoprotein(a) levels and metabolic syndorome and its components on coronary artery disease patients

Abstract Purpose Neele DM (Diabetologia 1999) showed that insulin suppressed apolipoprotein(a) synthesis by primary cultures of cynomolgus monkey hepatocytes. Therefore, there is a possibility that inverse association exists between lipoprotein(a) [Lp(a)] and metabolic syndorome (Mets) with insulin resistance/hyperinsulinemia for coronary atherosclerosis. Sung KC (Nutr Metab Cardiovasc Dis 2013) described the inverse association between Lp(a) levels and Mets and its components on an asian occupational cohort. And high levels of Lp(a) were associated with preclinical atherosclerosis, as evaluated by coronary calcium score with cardiac computed tomography. There is no similar examination on coronary artery disease (CAD) patients. The purpose is to examine similar considerations on CAD patients. Method 610 subjects with angiographically demonstrated CAD were enrolled. The patients who receiving medication for dyslipidemia and Insulin administration were excluded. The blood samples for laboratory tests were collected after an over night fast. Subjects were divided into four groups according to quartiles of Lp(a) levels (mg/dL). Ranges of quartile groups of Lp(a) were Q1: &amp;lt;9.0, Q2: 9.0–&amp;lt;16.0, Q3: 16.0–&amp;lt;30.0, Q4: ≥30.0. Results The inverse association Lp(a) levels and Mets and its component. The comparison of Q1 (bottom quartile) versus Q4 (top quartile) was shown below; the comorbidity rate of Mets 19.5% versus 8.0% (p&amp;lt;0.01), BMI (kg/m2) 23.5 versus 22.7 (p&amp;lt;0.05), trigyceride (mg/dL) 144.0 versus 107.5 (p&amp;lt;0.0001), HDL cholesterol (mg/dL) 46.8 versus 50.7 (p&amp;lt;0.05), the comorbidity rate of hypertension 60.4% versus 50.7% (p=0.084), glucose (mg/dL) 107.1 versus 100.6 (p&amp;lt;0.05), insulin (μU/mL) 8.49 versus 5.85 (p&amp;lt;0.0001), HOMA-R 2.26 versus 1.44 (p&amp;lt;0.0001). The mean number of diseased coronary vessel was higher in the Q4 group (2.07) than in the Q1 group (1.87) (p&amp;lt;0.05). Conclusion There was the inverse association between Lp(a) levels and Mets and its components on CAD patients. The robust association was found between Lp(a) levels and severity of coronary atherosclerosis despite this inverse correlation. Funding Acknowledgement Type of funding source: None

In Vitro Hepatic Uptake in Human and Monkey Hepatocytes in the Presence and Absence of Serum Protein and Its In Vitro to In Vivo Extrapolation.

It is well documented that human hepatic clearance based on in vitro metabolism or transporter assays systematically resulted in underprediction; therefore, large empirical scalars are often needed in either static or physiologically based pharmacokinetic (PBPK) models to accurately predict human pharmacokinetics (PK). In our current investigation, we assessed hepatic uptake in hepatocyte suspension in Krebs-Henseleit buffer in the presence and absence of serum. The results showed that the unbound intrinsic active clearance (CLu,int,active) values obtained by normalizing the unbound fraction in the buffer containing 10% serum were generally higher than the CLu,int,active obtained directly from protein free buffer, suggesting "protein-facilitated" uptake. The differences of CLu,int,active in the buffer with and without protein ranged from 1- to 925-fold and negatively correlated to the unbound serum binding of organic anion transporting polypeptide substrates. When using the uptake values obtained from buffer containing serum versus serum-free buffer, the median of scaling factors (SFs) for CLu,int,active reduced from 24.2-4.6 to 22.7-7.1 for human and monkey, respectively, demonstrating the improvement of in vitro to in vivo extrapolation in a PBPK model. Furthermore, values of CLu,int,active were significantly higher in monkey hepatocytes than that in human, and the species differences appeared to be compound dependent. Scaling up in vitro uptake values derived in assays containing species-specific serum can compensate for the species-specific variabilities when using cynomolgus monkey as a probe animal model. Incorporating SFs calibrated in monkey and together with scaled in vitro data can be a reliable approach for the prospective human PK prediction in early drug discovery. SIGNIFICANCE STATEMENT: We investigated the protein effect on hepatic uptake in human and monkey hepatocytes and improved the in vitro to in vivo extrapolation using parameters obtained from the incubation in the present of serum protein. In addition, significantly higher active uptake clearances were observed in monkey hepatocytes than in human, and the species differences appeared to be compound dependent. The physiologically based pharmacokinetic model that incorporates scaling factors calibrated in monkey and together with scaled in vitro human data can be a reliable approach for the prospective human pharmacokinetics prediction.

Metabolic profiling of senkyunolide A and identification of its metabolites in hepatocytes by ultra-high-performance liquid chromatography combined with diode-array detector and high-resolution mass spectrometry.

Senkyunolide A is one of the bioactive constituents originally isolated from Ligusticum chuanxiong Hort. To better understand the action of this constituent, it is necessary to study the metabolic profiles in different species. For the metabolic stability study, senkyunolide A at a concentration of 0.5 μM was individually incubated with hepatocytes of mouse, rat, dog, monkey and human at 37°C for 2 h. For metabolite profiling and identification, senkyunolide A (10 μM) was incubated with hepatocytes and the incubation samples were analyzed by ultra-high-performance liquid chromatography combined with diode-array detector and high-resolution mass spectrometry (UHPLC/DAD-HRMS). The identities of the metabolites were characterized by accurate masses, product ions and retention times. Senkyunolide A was metabolically unstable in hepatocytes. The in vitro half-lives were 136.2, 60.6, 33.65, 55.96 and 138 min in mouse, rat, dog, monkey and human hepatocytes, respectively. Furthermore, a total of 14 metabolites were detected. M1 and M9 were the most abundant metabolites in all species. The metabolic pathways of senkyunolide A involved the following pathways: (1) hydroxylation to form 10- and 11-hydroxysenkyunolide A, which further underwent epoxidation followed by GSH conjugation; (2) epoxidation followed by epoxide hydrolysis or GSH conjugation; and (3) aromatization to form 3-butylphthalide followed by hydroxylation. Hydroxylation, epoxidation, aromatization and GSH conjugation were the main metabolic pathways of senkyunolide A. This study provides an overview of the metabolic profiles of senkyunolide A, which is helpful for a better understanding of the action of this compound.

Comparison of the inducibility of CYP mRNA exposed to typical inducers in fresh and cryopreserved cynomolgus monkey hepatocytes

Herein, we evaluated CYPs and their nuclear receptor mRNA induction by exposure to typical inducers, omeprazole, rifampicin, and phenobarbital in cynomolgus monkey hepatocytes. Six freshly-isolated hepatocytes and 6 cryopreserved hepatocytes from cynomolgus monkey liver were prepared for a 14-day monolayer culture, 28-day co-culture with feeder cells, and 28-day 3D spheroid culture with feeder cells. Omeprazole and rifampicin respectively induced CYP1A1 and CYP3A8 mRNAs, while phenobarbital induced CYP2C43, CYP2C75, and CYP3A8, and slightly induced CYP2B6. The nuclear receptors AHR, PXR, and CAR mRNA levels, which were activated by omeprazole, rifampicin, and phenobarbital, respectively, tended to decrease via exposure to inducers despite the increase in CYP mRNA levels. These trends were similar for all three culture methods. No evident difference was observed in CYP mRNA induction between fresh and cryopreserved hepatocytes. Based on mRNA levels, the co-culture and 3D spheroid culture methods are more reasonable than monolayer culture for CYP evaluation, because the use of feeder cells can reduce the number of hepatocytes, improve the cell adhesion, and maintain the mRNA expression levels. In addition, co-culture method is more cost-effective, as common culture plates can be used.

Fluoroquinolones suppress gluconeogenesis by inhibiting fructose 1,6-bisphosphatase in primary monkey hepatocytes

Dysglycemia is one of the most serious adverse events associated with the clinical use of certain fluoroquinolones. The purpose of this study was to investigate the effects of the representative fluoroquinolones moxifloxacin and gatifloxacin on hepatic gluconeogenesis using primary monkey hepatocytes. Glucose production was induced after the cells were incubated for 4 h with 10 mM sodium lactate and 1 mM sodium pyruvate as gluconeogenic substrates. Under these conditions, moxifloxacin and gatifloxacin dose-dependently suppressed gluconeogenesis at concentrations of 100 μM or higher. Transcriptome analysis of rate-limiting enzymes involved in hepatic gluconeogenesis revealed that moxifloxacin and gatifloxacin at a concentration of 1000 μM did not affect the expression of key gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase, glucose 6-phosphatase, and fructose 1,6-bisphosphatase. Furthermore, metabolome analysis, in vitro glucose production assay using additional gluconeogenic substrates, and fructose 1,6-bisphosphatase assay using the cell extracts showed that fluoroquinolones enzymatically suppressed hepatic gluconeogenesis by inhibiting fructose 1,6-bisphosphatase. These inhibitory effects may involve in the clinically relevant dysglycemia associated with fluoroquinolones in human.

Woolly Monkey-HBV Infection in Squirrel Monkeys as a Surrogate Nonhuman Primate Model of HBV Infection.

Development of curative therapies for chronic hepatitis B virus (HBV) infection will likely require new animal models. Here, we evaluate HBV infection in squirrel monkeys based on the high‐sequence homology of the HBV receptor, Na+/taurocholate co‐transporting peptide (NTCP), between humans and squirrel monkeys. HBV PreS1 peptide was examined for binding human and squirrel monkey NTCP. Immunodeficient Fah −/−, NOD, Rag1 −/−, Il2Rg null (FNRG) mice engrafted with human or squirrel monkey hepatocytes were challenged with HBV or Woolly Monkey HBV (WMHBV). In addition, adult squirrel monkeys were inoculated with HBV, WMHBV, adeno‐associated virus containing an infectious genome of HBV (AAV‐HBV), and AAV‐WMHBV. Finally, neonate squirrel monkeys were assessed for the potential of chronic infection with WMHBV. PreS1 peptide efficiently bound to human and squirrel monkey NTCP but not to mouse or capuchin NTCP. FNRG mice engrafted with squirrel monkey hepatocytes were susceptible to infection by WMHBV but not human HBV. Similarly, adult squirrel monkeys could be infected with WMHBV but not human HBV, whereas chimeric mice engrafted with human hepatocytes were susceptible to HBV but not WMHBV. Infection of squirrel monkeys with AAV‐WMHBV yielded maximum viremia of 108 genomes/mL with detectable virus for up to 8 months. Notably, covalently closed circular DNA was detected in the liver of these animals. Infection of neonates with WMHBV led to detectable viremia for up to 6 months. Conclusions: Adult and neonate squirrel monkeys exhibited prolonged WMHBV viremia lasting 6‐8 months. This is greater than twice the duration of viremia achieved in other nonhuman primates and suggests that squirrel monkeys may be a suitable model for testing HBV therapeutics.

Organic Anion-Transporting Polypeptide Genes Are Not Induced by the Pregnane X Receptor Activator Rifampin: Studies in Hepatocytes In Vitro and in Monkeys In Vivo.

Induction potentials of the pregnane X receptor (PXR) activator rifampin (RIF) on transporter genes [e.g., organic anion-transporting polypeptides (OATPs)] are still in its infancy or remain controversial in the field. The present investigations characterized changes in transporter gene expression by RIF in sandwich-cultured hepatocytes from multiple donors of human and cynomolgus monkey using real-time quantitative reverse transcription polymerase chain reaction method. Three-day treatment of RIF significantly induced CYP3A4 (∼60-fold induction), but not CYP1A2 and CYP2D6 genes. SLC51B was the most highly induced uptake transporter gene (>10-fold) in both human and monkey hepatocytes. A greater induction of CYP2C9 was observed in monkey hepatocytes than that in humans. ATP-binding cassette (ABC)B1 and ABCC2 were induced slightly above 2-fold in human and monkey hepatocytes and appeared to be dose-dependent. The induction of OATP and other transporter genes was generally less than 2-fold and considered not clinically relevant. SLCO2B1 was not detectable in monkey hepatocytes. To investigate in vivo OATP induction, RIF (18 mg/kg per day) was orally dosed to cynomolgus monkeys for 7 days. Pitavastatin and antipyrine were intravenously dosed before and after RIF treatment as exogenous probes of OATP and CYP activities, respectively. Plasma coproporphyrin-I (CP-I) and coproporphyrin-III (CP-III) were measured as OATP endogenous biomarkers. Although a significant increase of antipyrine clearance (CL) was observed after RIF treatment, the plasma exposures of pitavastatin, CP-I, and CP-III remained unchanged, suggesting that OATP function was not significantly altered. The results suggested that OATP transporters were not significantly induced by PXR ligand RIF. The data are consistent with current regulatory guidances that the in vitro characterization of transporter induction during drug development is not required. SIGNIFICANCE STATEMENT: Organic anion-transporting polypeptide (OATP) genes were not induced by rifampin in sandwich-cultured human and monkey hepatocytes OATP functions measured by OATP probe pitavastatin and endogenous marker coproporphyrins were not altered in monkeys in vivo by 7-day rifampin treatment. The data suggested that OATP transporters are unlikely induced by the pregnane X receptor ligand rifampin, which are consistent with current regulatory guidances that the in vitro characterization of OATP1B induction during drug development is not required.

Comparison of mRNA expression profiles of drug-metabolizing enzymes and transporters in fresh and cryopreserved cynomolgus monkey hepatocytes

In this study, freshly isolated and cryopreserved cynomolgus monkey hepatocytes were seeded on Cell-able® plates with feeder cells to form spheroids and were cultured for 28 days. As a control, hepatocytes were also cultured with or without feeder cells on collagen-coated plates. We verified the mRNA expression levels of drug-metabolizing enzyme-related genes and the leakage of enzymes (AST, ALT, LDH, and γ-GTP) as indicators of cell survival. As a result, the patterns of target mRNA expression in fresh and cryopreserved hepatocytes were very similar during the culture period between culture methods. mRNA expression levels were highly maintained at day 28 using the 3D spheroid and co-culture methods, demonstrating that these methods are useful for maintenance of liver function. Leakage of AST and ALT was higher at day 3 but decreased at day 14. LDH was not detected, suggesting that the cell viability was also maintained during the culture period. Furthermore, the functional differences between fresh and cryopreserved hepatocytes were not clearly detected. The co-culture method was useful for long-term culture not requiring 3D structure, and the 3D spheroid culture method was effective as well. With these techniques, cynomolgus monkey hepatocytes are expected to exhibit smaller individual differences and high reproducibility.

Characterization of Hepatocytes Uptake Clearance of Organic Anion Transporting Polypeptide (OATPs) Substrates in Human and Cynomolgus Cryopreserved Hepatocytes

Transporter‐mediated clearance plays significant roles in drug bioavailability and elimination, and evaluation of potential transporter‐mediated drug‐drug interactions (DDI) is recommended by regulatory agencies during drug development. Currently, the direct extrapolation from in vitro to in vivo is a common approach for human clearance prediction for the compounds that are metabolized by hepatic cytochrome P450 enzymes; however, challenge remains when using the similar approaches in prediction of transporter‐mediated clearance. Recent publications attempted to establish the in‐vitro‐to‐ in vivo scaling based on hepatocyte uptake studies and in vivo pharmacokinetic (PK) data from the preclinical animals. However, the differences in homology of transporter proteins and the associated substrate specificity in transporters between human and preclinical animals complicate the prediction using the correcting factors obtained from the preclinical animals' in‐vitro‐to‐ in vivo scaling. In this study, we obtained the in vitro hepatic uptake clearance in cynomolgus monkey and human for 14 literature compounds that were known as OATPs substrates and had clinical DDI reported. Hepatic uptake was conducted using the oil‐spin method. For each selected substrate, the uptake assay was conducted in the time course from 0.25 minute to 15 minutes in KHB buffer with 10% serum. The uptake clearance was estimated from the linear uptake phase. For each selected substrate, the uptake clearance was characterized in three lots (including single donor and pooled donors lots) of human and monkey cryopreserved hepatocytes. In addition, we tested different lots of human (7 lots) and monkey (10 lots) cryopreserved hepatocytes using rosuvastatin as a control probe to examine the variability among lots and donors. In summary, rosuvastatin uptake clearance in cynomolgus monkey hepatocytes was about 2.5 folds higher on average compared to that in human hepatocytes. Generally, for other OATPs substrates studied, hepatic uptake clearance in cynomolgus monkey appeared to be higher than that in human. Furthermore, variability of uptake clearance was also observed among lots and donors. The results obtained in the current investigations are useful for human prediction through understanding the source of variations and establishing the correlations of in vitro‐in vivo scaling.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Identification of novel glutathione conjugates of terbinafine in liver microsomes and hepatocytes across species

1. Terbinafine (TBF), a common antifungal agent, has been associated with rare incidences of hepatotoxicity. It is hypothesized that bioactivation of TBF to reactive intermediates and subsequent binding to critical cellular proteins may contribute to this toxicity. In the present study, we have characterized the bioactivation pathways of TBF extensively in human, mouse, monkey, dog and rat liver microsomes and hepatocytes.2. A total of twenty glutathione conjugates of TBF were identified in hepatocytes; thirteen of these conjugates were also detected in liver microsomes. To the best of our knowledge, only two of these conjugates have been reported previously. The conjugates were categorized into three groups based on their mechanism of formation: (a) alkene/alkyne oxidation followed by glutathione conjugation, with or without N-demethylation, (b) arene oxidation followed by glutathione conjugation, with or without N-demethylation, and (c) N-dealkylation followed by glutathione conjugation of the allylic aldehyde, alcohol and acid intermediates.3. Differences were observed across species in the contributions of these pathways toward overall metabolic turnover. We conclude that, in addition to the glutathione conjugates known to form by Michael addition to the allylic aldehyde, there are other pathways involving the formation of arene oxides and alkene/alkyne epoxides that may be relevant to the discussion of TBF-mediated idiosyncratic drug reactions.

Comparison of uptake transporter functions in hepatocytes in different species to determine the optimal model for evaluating drug transporter activities in humans

A thorough understanding of species-dependent differences in hepatic uptake transporters is critical for predicting human pharmacokinetics (PKs) from preclinical data.In this study, the activities of organic anion transporting polypeptide (OATP/Oatp), organic cation transporter 1 (OCT1/Oct1), and sodium-taurocholate cotransporting polypeptide (NTCP/Ntcp) in cultured rat, dog, monkey and human hepatocytes were compared.The activities of hepatic uptake transporters were evaluated with respect to culture duration, substrate and species-dependent differences in hepatocytes. Longer culture duration reduced hepatic uptake transporter activities across species except for Oatp and Ntcp in rats. Comparable apparent Michaelis–Menten constant (Km,app) values in hepatocytes were observed across species for atorvastatin, estradiol-17β-glucuronide and metformin. The Km,app values for rosuvastatin and taurocholate were significantly different across species. Rat hepatocytes exhibited the highest Oatp percentage of uptake transporter-mediated permeation clearance (PSinf,act) while no difference in %PSinf,act of probe substrates were observed across species. The in vitro hepatocyte inhibition data in rats, monkeys and humans provided reasonable predictions of in vivo drug–drug interaction (DDIs) between atorvastatin/rosuvastatin and rifampin.These findings suggested that using human hepatocytes with a short culture time is the most robust preclinical model for predicting DDIs for compounds exhibiting active hepatic uptake in humans.