In contrast, in a prospective study of 50 patients with advanced gastrointestinal cancer including 30 patients with PC, UGT1A1-genotyping-guided dose modification of FOLFIRABRAX (irinotecan, fluorouracil, leucovorin, and nab-paclitaxel) with prophylactic pegfilgrastim was tolerable in patients with UGT1A1 wild type or UGT1A1*1/*28 genotypes. The gene discussed is UGT1A1; the disease is pachyonychia congenita.