Evaluation of the risk of EGFR tyrosine kinase inhibitor-induced diarrhea with cultured intestinal stem cells originated from crypts in monkeys and humans

Abstract

[Purpose] We aimed to evaluate the risk of EGFR tyrosine kinase inhibitors (EGFR-TKI)-induced diarrhea with cultured intestinal stem cells originated from crypts in monkeys and humans. [Methods] Isolated intestinal crypts were embedded in Matrigel and cultured in L-WRN conditioned media. After exposure to EGFR-TKIs, cellular ATP levels and LDH release were measured as markers of live and dead cells, respectively. [Results] EGFR-TKI exposure resulted in the decreased ATP levels prior to the increase in LDH release, suggesting the decreased intracellular metabolism. Susceptibility to ATP change was higher in afatinib compared with that in lapatinib, gefitinib and erlotinib, which corresponds to the high frequency of afatinib-induced diarrhea in the clinical situation. Toxic sensitivity of osimertinib, which selectively inhibits mutated type of EGFR and reduces diarrhea incidence, was lower than that of afatinib. Intra-spheroid drug accumulation ([TKI]) and [TKI]/K_d value was higher in afatinib, suggesting that toxic sensitivity corresponds to inhibition potency against EGFR. Afatinib is an irreversible EGFR inhibitor and recovery of decreased ATP levels was not confirmed even after drug removal from culture media. [Discussion] Cultured intestinal stem cells could capture the risks of EGFR-TKI-induced diarrhea. We revealed that cytotoxicity against intestinal stem cells could contribute to the occurrence of EGFR-TKI-induced diarrhea. Since toxic sensitivity reflected differences in inhibition potency and mode against EGFR, stem cell damage might be caused by on-target effect.