Comprehensive analysis of Excision repair complementation group 1, Glutathione S-transferase, Thymidylate synthase, and Uridine diphosphate glucuronosyltransferase 1A1 polymorphisms predictive for treatment outcome in patients with advanced gastric cancer treated with FOLFOX or FOLFIRI

Abstract

e15580 Background: Pharmacogenetic advances in cancer chemotherapy have the potential to predict clinical benefit to particular regimens. Oxaliplatin and irinotecan have shown to be effective in the treatment of gastric cancer. We assessed whether single nucleotide polymorphisms (SNPs) in ERCC1, GST, TS, and UGT1A1predicted overall survival in gastric cancer patients receiving FOLFOX and/or FOLFIRI chemotherapy. Methods: Total genomic DNA was extracted from whole blood of patient. The PCR- restriction fragment length polymorphism (RFLP) method was applied to detect the known variant sites of ERCC1, GST, TS, and UGT1A1. Results: Response rate of FOLFOX (N=75) was 24%. Grade 3–4 neutropenia and neurotoxicity were observed 34.7% and 16%, respectively. TTP and OS of 1st line administration of FOLFOX (N=35) was 3.1 months (95% CI, 0.1–6.1 months) and 13.9 months (95% CI, 12.2–15.6 months). Only the GSTM1 positive genotype showed a significantly better time to progression (P=0.023). But significant genotype variation of TS, GST and ERCC1,which assumed to affect to activity of oxaliplatin was not observed to RR, toxicity, and overall survival. Response rate of FOLFIRI (N=74) was 23%. Grade 3–4 neutropenia and diarrhea were observed 55.4% and 9.5%, respectively. TTP and OS of 1st line administration of FOLFIRI (N=33) was 4.9 months (95% CI, 3.5–6.4 months) and 19.0 months (95% CI, 8.5–29.5months). Low expression type (2R/2R, 2R/3C, and 3C/3C) of TS was associated with high incidence of grade ≥3 neutropenia. But significant genotype variation of UGT1A1,which assumed to affect to toxicity of irinotecan was not observed to RR, toxicity, and survival. Conclusions: In this study, GSTM1 positive genotype showed a significantly better time to progression in the advanced gastric cancer treated with FOLFOX. Low expression type (2R/2R, 2R/3C, and 3C/3C) of TS was associated with high incidence of grade ≥3 neutropenia in the advanced gastric cancer treated with FOLFIRI. Well designed prospective trial will be clearly identifying relations between chemotherapy and genetic variations. No significant financial relationships to disclose.