Gilbert's Syndrome and Irinotecan Toxicity: Combination with UDP-Glucuronosyltransferase 1A7 Variants Increases Risk

Irinotecan toxicity is more likely in patients with Gilbert's syndrome carrying the UGT1A1*28 allele combined with reduced function UGT1A7 N129K/R131K and UGT1A7-57T/G SNP. Based on the ability of UGT1A7 to metabolize and eliminate the active irinotecan metabolite 7-ethyl-10-hydroxycamptothecin, the UGT1A1/UGT1A7 SNP combination haplotype appears to be a superior risk predictor than Gilbert's syndrome alone.