An In vivo-In vitro Correlation of Hepatic Clearance for Metabolism by Non-CYP with Custom Pooled Hepatocytes

The use of human pooled hepatocytes as a preclinical predictor of human pharmacokinetics for non-cytochrome P450 (CYP) metabolism has attracted attention at drug discovery due to their broad spectrum of metabolic enzyme activity, large lots production, and tight variation. In order to verify usability of human pooled hepatocytes for non-CYP metabolism evaluation, first, we evaluated 18 compounds primarily metabolized by non-CYP enzymes including UDP-glucuronosyltransferase, reductase, aldehyde oxidase, flavin-containing monooxygenase, and monoamineoxidase in individual hepatocytes and pooled hepatocytes from the same donors. The intrinsic clearance in pooled hepatocytes showed more than 70% of average clearance value in individuals in 16/18 compounds which suggest pooled hepatocytes maintained an average activity of the individual hepatocytes. Subsequently, in vivo-in vitro correlation (IVIVC) analysis using pooled hepatocytes were performed in 24 compounds. Although further studies are needed for IVIVC using hepatocytes as under-prediction trend or large variation were observed in this analysis, quantitative hepatic clearance prediction was successfully observed in aldehyde oxidase substrates using empirical scaling factor. The possible reasons for under-prediction or variation, and the possibility to improve the predictability for other non-CYP enzyme were also discussed.