Faculty Member

Irinotecan is a first-line treatment for colorectal cancer and the prodrug of 7-ethyl-10-hydroxy-camptothecin (SN-38). However, its fatal gastrointestinal (GI) toxicity raises serious concern. In liver, irinotecan generates its inactive metabolite, SN-38G via UDP-glucuronosyltransferase (UGT)1A1. Subsequently, SN-38G is excreted into GI tract where it is reactivated by microbiome to yield the toxic metabolite, SN-38. Activation of toll-like receptor (TLR)/myeloid differentiation primary response 88 (MyD88) by bacterial endotoxin decreases drug-metabolizing enzymes. In this study, we treated C57BL6/J mice with 50 mg/kg irinotecan once daily until observing grade 4 diarrhea. Mice were sacrificed on day0, day2 and day8. Based on the finding in C57BL6/J mice, we repeated the treatment in Tlr2-/-Tlr4-/- and Myd88-/- mice to determine the impact of inflammation on UGT metabolism. Our toxicity study in C57BL6/J mice …