Applicability of second-generation upcyte®^{®} human hepatocytes for use in CYP inhibition and induction studies

Human upcyte$^{®}$ hepatocytes are proliferating hepatocytes that retain many characteristics of primary human hepatocytes. We conducted a comprehensive evaluation of the application of second-generation upcyte$^{®}$ hepatocytes from four donors for inhibition and induction assays using a selection of reference inhibitors and inducers. CYP1A2, CYP2B6, CYP2C9, and CYP3A4 were reproducibly inhibited in a concentration-dependent manner and the calculated IC$_{50}$ values for each compound correctly classified them as potent inhibitors. Upcyte$^{®}$ hepatocytes were responsive to prototypical CYP1A2, CYP2B6, CYP2C9, and CYP3A4 inducers, confirming that they have functional AhR-, CAR-, and PXR-mediated CYP regulation. A panel of 11 inducers classified as potent, moderate or noninducers of CYP3A4 and CYP2B6 were tested. There was a good fit of data from upcyte$^{®}$ hepatocytes to three different predictive models for CYP3A4 induction, namely the Relative Induction Score (RIS), AUC$_{u}$/F$_{2}$, and C$_{max,u}$/Ind$_{50}$. In addition, PXR (rifampicin) and CAR-selective (carbamazepine and phenytoin) inducers of CYP3A4 and CYP2B6 induction, respectively, were demonstrated. In conclusion, these data support the use of second-generation upcyte$^{®}$ hepatocytes for CYP inhibition and induction assays. Under the culture conditions used, these cells expressed CYP activities that were equivalent to or higher than those measured in primary human hepatocyte cultures, which could be inhibited or induced by prototypical CYP inhibitors and inducers, respectively. Moreover, they can be used to predict in vivo CYP3A4 induction potential using three prediction models. Bulk availability of cells from multiple donors makes upcyte$^{®}$ hepatocytes suitable for DDI screening, as well as more in-depth mechanistic investigations