UGT1A1 and biliary tract cancer: In another study, Sharma et al. reported that dose-limiting toxicity occurred in 4/10 (40%) in DV (UGT1A1*28/*28) patients who received mFOLFIRINOX with a 90 mg/m2 irinotecan dose, and this dose reduction was not tolerable for DV patients with pancreatic and biliary tract cancers [13].