Prediction of the Clinical Risk of Drug-Induced Cholestatic Liver Injury Using an In Vitro Sandwich Cultured Hepatocyte Assay.

Drug-induced liver injury (DILI) is of concern to the pharmaceutical industry, and reliable preclinical screens are required. Previously, we established an in vitro bile acid-dependent hepatotoxicity assay that mimics cholestatic DILI in vivo. Here, we confirmed that this assay can predict cholestatic DILI in clinical situations by comparing in vitro cytotoxicity data with in vivo risk. For 38 drugs, the frequencies of abnormal increases in serum alkaline phosphatase (ALP), transaminases, gamma glutamyltranspeptidase (γGT), and bilirubin were collected from interview forms. Drugs with frequencies of serum marker increases higher than 1% were classified as high DILI risk compounds. In vitro cytotoxicity was assessed by monitoring lactate dehydrogenase release from rat and human sandwich-cultured hepatocytes (SCRHs and SCHHs) incubated with the test drugs (50 µM) for 24 hours in the absence or presence of a bile acids mixture. Receiver operating characteristic analyses gave optimal cutoff toxicity values of 19.5% and 9.2% for ALP and transaminases in SCRHs, respectively. Using this cutoff, high- and low-risk drugs were separated with 65.4-78.6% sensitivity and 66.7-79.2% specificity. Good separation was also achieved using SCHHs. In conclusion, cholestatic DILI risk can be successfully predicted using a sandwich-cultured hepatocyte-based assay.

Establishment of a Drug-Induced, Bile Acid-Dependent Hepatotoxicity Model Using HepaRG Cells.

Bile acid (BA) retention within hepatocytes is an underlying mechanism of cholestatic drug-induced liver injury (DILI). We previously developed an assay using sandwich-cultured human hepatocytes (SCHHs) to evaluate drug-induced hepatocyte toxicity accompanying intracellular BA accumulation. However, due to shortcomings commonly associated with the use of primary human hepatocytes (e.g., limited availability, lot-to-lot variability, and high cost), we examined if the human hepatic stem cell line, HepaRG, might also be applicable to our assay system. Consequently, mRNA expression levels of human BA efflux and uptake transporters were lower in HepaRG cells than in SCHHs but higher than in HepG2 human hepatoma cells. Nevertheless, HepaRG cells and SCHHs showed similar toxicity responses to 22 selected drugs, including cyclosporine A (CsA). CsA (10 µM) was cytotoxic toward HepaRG cells in the presence of BAs and also reduced the biliary efflux rate of [(3)H]taurocholic acid from 38.5% to 19.2%. Therefore, HepaRG cells are useful for the evaluation of BA-dependent drug toxicity caused by biliary BA efflux inhibition. Regardless, the prediction accuracy for cholestatic DILI risk was poor for HepaRG cells versus SCHHs, suggesting that our DILI model system requires further improvements to increase the utility of HepaRG cells as a preclinical screening tool.