OWE-019 Mechanisms of chemotherapy-induced diarrhoea

IntroductionBcr-Abl inhibitors, such as bosutinib and imatinib, are predominantly used for treatment of chronic myeloid leukaemia. However, lower gastrointestinal toxicity, such as diarrhoea, is a prevalent adverse drug reaction (ADR). For example, bosutinib and imatinib cause diarrhoea in up to 90% and 50% of patients, respectively.1 This can decrease patient quality of life, treatment efficacy and in severe cases cause patient hospitalisation. We aim to elucidate the mechanism of Bcr-Abl inhibitor-induced diarrhoea to help abrogate the aforementioned issues.MethodsCaco-2 cells (human colorectal cancer cells resembling small intestinal cells) were differentiated into monolayers of polarised enterocytes and utilised as an in vitro model. Cells were seeded into transwells and electrical resistance or flux of FITC-dextran (a fluorescently labelled polysaccharide) across the monolayer was measured to assess changes in paracellular permeability. Enteroids (small intestinal organoids) produced from male BALB/c mice were used as an ex vivo model. Changes in permeability of enteroids were determined by leakage of injected FITC-dextran out of the enteroid. Changes in mRNA levels, protein levels and protein localization of tight junction components were studied using RTqPCR, immunoblotting and immunofluorescence, respectively. Drug-induced cell death was assessed by CellTitreGlo and Toxilight assays for Caco-2 cells and enteroids, respectively. Results were analysed by ANOVA and are representative of ≥3 independent experiments.Results25 µM bosutinib increased paracellular permeability of Caco-2 monolayers to ions and FITC-dextran (ANOVA, p