Association of XRCC3 and XPD751 SNP with efficacy of platinum-based chemotherapy in advanced NSCLC patients

INTRODUCTION

The aim of this study was to investigate whe- ther X-ray repair cross-complementing group 3 (XRCC3) and xeroderma pigmentosum group D (XPD) single nucleotide polymorphism (SNP) affects the outcome of platinum- based chemotherapy in advanced non-small-cell lung cancer (NSCLC) patients.

MATERIAL AND METHODS

From September 2005 to June 2009, 355 advanced-stage NSCLC patients were accrued to compare the SNP variants with the outcome of platinum-based chemotherapy. TaqMan RT-PCR was used to evaluate the SNPs of the XRCC3 codon241 (Thr/Met) and XPD codon751 (Lys/Gln) DNA repair genes.

RESULTS

There was a lack of association between the studied SNPs and the response rate, progression-free survival or overall survival (OS) in the whole population. However, subgroup analysis revealed that XRCC3 241 Thr/Met or Met/Met allele was associated with marginally significantly longer OS than XRCC3 Thr/Thr allele (19.0 m vs. 12.5 m, p=0.081) in the patients treated with gemcitabine/ cisplatin or carboplatin (GP/GC) while it was correlated with a significantly shorter OS in the patients treated with non GP/GC (9.3 m vs. 16 m, p=0.003). XPD751 Lys/Lys had an association with statistical significantly longer OS than XPD751 Lys/Gln or Gln/Gln in the subgroup of elderly patients (14.10 m vs. 10 m, p=0.019) and patients with non-adenocarcinoma (12.6 m vs. 9 m, p=0.042).

CONCLUSIONS

XRCC3 Thr241Met played an opposite role in predicting prognosis of chemotherapy in NSCLC patients according to the first-line regimens. XPD 751 Lys/ Lys might be a better prognostic marker of elderly or noncarcinoma NSCLC subgroup treated with platinum-based chemotherapy.

Predictive effects of ERCC1 and XRCC3 SNP on efficacy of platinum-based chemotherapy in advanced NSCLC patients

OBJECTIVE

The purpose of the study was to investigate whether single-nucleotide polymorphisms of deoxyribonucleic acid repair gene excision repair cross-complementing group 1 at codon 118 and X-ray repair cross-complementing group 3 at codon 241 affected clinical outcomes in advanced non-small cell lung cancer patients receiving first-line platinum-based chemotherapy.

METHODS

A total of 130 patients treated with platinum-based doublets were examined for genotyping of excision repair cross-complementing group 1 118 and X-ray repair cross-complementing group 3 241 in peripheral blood lymphocytes with the method of the TaqMan assay plus the real-time polymerase chain reaction method. Multivariate logistic or Cox's regression analyses were used to adjust for possible confounding variables.

RESULTS

There were no differences in clinical characteristics among the different single-nucleotide polymorphisms. Overall response rate in the 130 patients was 20% with 85.4% of disease control rate. Followed up to 31 March 2008, there were 47 patients still alive. Overall survival was 15 months. No relationship was found between excision repair cross-complementing group 1 or X-ray repair cross-complementing group 3 single-nucleotide polymorphisms and tumor response to platinum-based chemotherapy. A significant correlation was found between excision repair cross-complementing group 1 118 C/T single-nucleotide polymorphisms and survival (P = 0.003). In the multivariate model, the survival was highly related with excision repair cross-complementing group 1 118 C/T or T/T genotypes and tumor response to chemotherapy.

CONCLUSIONS

Overall survival was significantly improved in the patients with excision repair cross-complementing group 1 118 T/T or C/T treated by platinum-based chemotherapy.

An introduction to molecular targeted therapy of cancer

The rapidly advancing elucidation of molecular targets in human cancers during the last decade has provided an excellent basis for the development of novel therapeutics. A huge variety of potential target structures have been identified, many of which are already being exploited for therapeutic purposes. This review introduces the reader into the concept of molecular targeted therapies, and provides some prototypic examples.

How could pharmacogenomics help improve patient survival?

Increasing knowledge regarding multiple genetic disturbances found in human lung cancers, particularly non-small cell lung cancer (NSCLC), have enabled predictive markers to be used in specialised centres in tailoring chemotherapy regimens and improving survival and response in subgroups of patients. Impressive responses are observed in patients with epidermal growth factor receptor (EGFR) tyrosine kinase mutations following treatment with gefitinib and erlotinib; and methylation of the mitotic checkpoint gene 14-3-3sigma in circulating tumour serum DNA predicts response to cisplatin/gemcitabine therapy. Expression of markers of DNA repair, ERCC1, RRM1 and BRCA1 are also determinants of response to cisplatin/gemcitabine, with low levels of mRNA predicting improved survival. Patients harbouring the Met/Met mutation in XRCC3 240 have significantly better survival compared with other mutations. These findings are presented in this article, as well as their relevance in customising chemotherapy - illustrated by a hypothetical model guiding treatment decisions in the management of NSCLC.

Gene Expression and Polymorphisms of DNA Repair Enzymes: Cancer Susceptibility and Response to Chemotherapy

Platinum compounds play a central role in cancer chemotherapy. Although treatment is limited by side effects, they continue to have widespread application. One of the main aims of clinical or translational research in cancer is the search for genetic factors that could foresee treatment outcomes, in biologic activity and toxic effects. This genetic analysis might allow selection of patients who will have the greatest benefit from chemotherapy. Furthermore, a better knowledge of the underlying molecular profile of the host and the tumor will facilitate screening for lung cancer susceptibility and tailoring of chemotherapy in individual patients, choosing those most likely to respond, adjusting doses more precisely in order to reduce less adverse effects, and establishing safety profiles based on individual genetic analyses. Herein, we discuss current knowledge regarding gene expression and polymorphisms of DNA repair enzymes in regard to cancer susceptibility and response to chemotherapy.