Irinotecan-Induced Toxicity: A Pharmacogenetic Study Beyond UGT1A1

Area of Science:

• Pharmacogenomics
• Oncology
• Drug Metabolism

Background:

• Irinotecan treatment is associated with dose-limiting side effects impacting patient quality of life.
• Understanding genetic factors influencing irinotecan metabolism and transport is crucial for managing toxicity.
• Focus on carboxylesterases (CES) and drug transporters, beyond UGT1A1, in irinotecan metabolism.

Purpose of the Study:

• To investigate the correlation between single nucleotide polymorphisms (SNPs) in irinotecan metabolism and transport genes and irinotecan-related toxicity.
• To identify potential genetic markers for predicting irinotecan-induced adverse events.

Main Methods:

• Genotyping of 15 SNPs in CES1, CES2, SLCO1B1, ABCB1, ABCC2, and ABCG2 genes in patients enrolled in the Code Geno or IRI28 studies.
• Analysis of irinotecan-related toxicity in 299 evaluable patients.
• Statistical analysis to determine the association between SNPs and toxicity, including odds ratios and confidence intervals.

Main Results:

• 28.8% of patients experienced severe irinotecan-related toxicity.
• ABCG2 c.421C>A variant allele carriers showed a significantly higher risk of toxicity (OR 1.88).
• CES1 variants (c.1165-41C>T and n.95346T>C) were associated with a lower risk of thrombocytopenia.

Conclusions:

• Single nucleotide polymorphisms (SNPs) in ABCG2 and CES1 genes may serve as predictive markers for irinotecan-induced toxicity.
• These findings could contribute to personalized medicine approaches in irinotecan therapy.
• Further research is warranted to validate these genetic markers in clinical practice.