Related Experiment Video
Updated: Jul 13, 2026

Multi-Gene Single Nucleotide Polymorphism Detection in Gastric Cancer Based on Ion Semiconductor Sequencing Platform
Published on: May 10, 2024
Increased frequency of uridine diphosphate glucuronosyltransferase 1A1 7/7 in patients experiencing severe
Marwan G Fakih1, Mary Ellen Ross, Petr Starostik
1Department of Medicine, Roswell Park Cancer Institute, Buffalo, NY 14263, USA. marwan.fakih@roswellpark.org
Background:
Uridine diphosphate glucuronosyltransferase (UGT) 1A1 7/7 polymorphism has been linked with an increased risk of irinotecan-induced severe toxicities. We evaluated UGT1A1 polymorphism in patients developing grade 3/4 toxicity after initiation of irinotecan to determine the frequency of this polymorphism in this population.
Patients And Methods:
Twenty patients with grade 3/4 irinotecan-induced toxicity underwent UGT1A1 genotyping in an exploratory study. The frequency of UGT1A1 7/7 and the pattern of toxicity associated with this polymorphism were described.
Results:
Forty percent of patients with grade 3/4 toxicities had a UGT1A 7/7 polymorphism (vs. 10% in general population). Six of 7 patients requiring hospitalization, 7 of 10 patients with grade 4 neutropenia, and 3 of 3 patients with grade 4 diarrhea, had UGT1A1 7/7 polymorphism.
Conclusion:
Uridine diphosphate glucuronosyltransferase 1A1 7/7 is prevalent in patients with irinotecan grade 3/4 toxicity, especially in patients with treatment-related hospitalizations and grade 4 toxicities. Our data support the need for more prospective studies that evaluate the predictive value of UGT1A1 as well as UGT1A1-based dosing in patients receiving irinotecan.
Related Concept Videos
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Phase II Reactions: Glucuronidation
Drug toxicity: Idiosyncratic Reactions
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
Drug Accumulation During Multiple Dosing: Intermittent IV Infusions
