Among the cancer patient population, resistance to therapy is a major cause for therapeutic
failure and for human sufferings, especially for the cancer with poor prognosis. Therefore,
finding factors that contribute to drug resistance is a major research interest. In
this study, we have investigated whether polymorphisms in genes that control import/export
of drugs (MDR1) and that repair DNA adducts (ERCC1) are involved with drug resistance
in non-small cell lung cancer (NSCLC) patients. We have recruited 95 patients with
advanced NSCLC (stages IIIB-IV) who were specifically treated with platinum-based
chemotherapy. We used the ligase detection reactions assay (LDR) to detect polymorphisms
in ERCC1 118C/T, and MDR1 2677T/A, E1/-129T/C, and C3435T in peripheral blood lymphocytes
from the patients. The haplotype of MDR1 gene single nucleotide polymorphisms (SNPs)
were analyzed using the SHEsis software platform on line. We found that none of the
single polymorphisms was associated with treatment response or related toxicity. However,
patients carrying at least one variant MDR1 2677 T allele was associated with a significantly
increased risk of drug resistance (OR=1.844, 95% CI=1.01-3.53, P=0.04) but also with
a significantly increased risk of gastrointestinal toxicity (P=0.03) but not hemato-,
hepato- or nephro-toxicities. Moreover, we analyzed the haplotypes of the three polymorphisms
in MDR1. The patients harboring the E1/-129T-2677T-3435C haplotype had a significantly
better response to chemotherapy compared with those having the other haplotypes (P=0.02,
95% CI=1.20-25.87), and a marginally significant association with increased risk of
gastrointestinal toxicity (P=0.02, 95% CI=1.15-3.88). Our results suggested that gene
polymorphisms in MDR1G2677T/A may be a predictive marker of platinum-based treatment
response and of secondary effects, especially gastrointestinal toxicity for advanced
NSCLC patients.
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