Background: Docetaxel-based chemotherapy regimens have demonstrated activity in advanced gastric cancer (AGC). However, a high rate of grade 3/4 hematotoxicity was reported with these regimens. Our purpose was to identify pharmacogenetic markers with potential to detect patients with increased risk to encounter severe hematotoxicity following treatment with 5-fluorouracil, leucovorin, oxaliplatin and docetaxel (FLOT).
Patients and methods: Polymorphisms of genes involved in DNA repair, drug transport and metabolism were determined in 50 AGC patients receiving FLOT within a phase II trial. DNA was extracted from peripheral blood. Genotyping was carried out using PCR-based techniques.
Results: Patients possessing TS-group A genotypes (2R/2R, 2R/3RC, 3RC/3RC) were at increased risk for grade 3/4 hematotoxicity compared with patients harboring a TS-group B genotype (2R/3RG, 3RC/3RG, 3RG/3RG). In all, 59% (20 of 34) of patients with TS-group A genotypes developed grade 3/4 hematotoxicity compared with 25% (4 of 16) of those having TS-group B genotypes (P=0.035). Grade 3/4 neutropenia occurred in 53% (18 of 34) of TS-group A patients compared with 19% (3 of 16) in TS-group B patients (P=0.032). Multivariate analyses identified TS-group A genotypes as significant predictors of grade 3/4 overall hematotoxicity {odds ratio (OR) 4.62 [95% confidence interval (CI) 1.22; 17.44], P=0.024} and neutropenia [OR 5.74 (95% CI 1.03; 32.08), P=0.047].
Conclusion: TS-promoter polymorphisms may be associated with hematotoxicity in AGC patients receiving FLOT.