Integrated “gut–liver”-on-a-chip (iGLoC): an immune-competent and metabolically active microphysiological model of the gut–liver axis for drug screening, validated by abemaciclib pharmacokinetics, hepatotoxicity, and drug–drug interaction studies

An immune-competent, metabolically active gut-liver microphysiological platform (iGLoC) was engineered to investigate the pharmacokinetics, metabolism, hepatotoxicity, and drug-drug interaction (DDI) liabilities of the oral CDK4/6 inhibitor abemaciclib. The system integrates a mucus-secreting Caco-2/HT-29 intestinal epithelium co-cultured with THP-1-derived macrophages and 3D HepG2 spheroids in interconnected PMMA/PDMS microfluidic chips linked by a controlled-flow bridging channel. Intestinal barrier morphology, tight-junction integrity, transepithelial electrical resistance, P-glycoprotein transport, and paracellular permeability were functionally validated, while hepatic spheroids exhibited stable albumin and urea secretion and pharmacologically inducible CYP3A4 activity relative to 2D HepG2 monolayers, while remaining less CYP3A4-competent than primary hepatocytes. Following apical dosing with abemaciclib, serial sampling from apical, basolateral, and hepatic chambers combined with a validated UPLC-MS/MS assay enabled time-resolved quantification of parent drug and major metabolites (M2, M20). The platform reproduced an oral-like disposition profile characterized by luminal depletion, a transient basolateral peak, and delayed hepatic appearance, along with formation of clinically relevant metabolites. Pre-treatment with rifampicin (CYP3A4/P-gp inducer) or clarithromycin (CYP3A4/P-gp inhibitor) and induction of colitis-like injury with dextran sulfate sodium generated distinct, mechanistically consistent alterations in intestinal permeability, metabolite output, and hepatic exposure that mirrored reported clinical DDIs and inflammation-associated variability. Abemaciclib also elicited concentration-dependent hepatocellular injury and modulation of gut-immune cytokine responses at clinically relevant levels. iGLoC innovates through immune-competent gut-liver integration under flow, quantitative clinical PK validation for abemaciclib, and mechanistic resolution of CYP3A4/P-gp DDIs and inflammation effects. Collectively, these data demonstrate that iGLoC represents a human-relevant organ-on-a-chip platform capable of evaluating oral bioavailability, first-pass metabolism, metabolite formation, hepatotoxicity, and drug interaction potential. The system shows promise for preclinical assessment of small-molecule therapeutics, including those used in precision oncology applications.