Inui, T., et al.
Caco-2 cells, which are widely used to evaluate the pharmacokinetics of orally administered drugs in the small intestine in vitro, have little or no CYP3A4 activity, which plays a major role in drug metabolism. In addition, it is difficult to accurately evaluate the function of transporters by using inhibitors of specific transporters due to the off-target nature of the inhibitors. In this study, we focused on the fact that biopsy-derived human intestinal organoid monolayers have high expression and activity of various pharmacokinetics-related genes including CYP3A4, and we produced human intestinal organoids lacking MDR1, a major transporter, and evaluated their utility. The results showed that knockout of MDR1 did not affect gene expression or activity of other drug-metabolizing enzymes and transporters. In addition, MDR1-KO monolayers were able to correctly evaluate the effects of drugs that use MDR1 as a substrate. On the other hand, MDR1 inhibitors on normal organoid monolayers could not correctly evaluate the effects of drugs using MDR1 as a substrate due to off-targeting of the inhibitors. Therefore, our results suggest that MDR1-KO human intestinal organoid-derived monolayers can evaluate MDR1 function more accurately than conventional evaluation systems. In the future, we would like to create a more accurate pharmacokinetic evaluation panel using organoid strains in which other pharmacokinetic-related molecules are knocked out.