Association between polymorphisms of ERCC1 and XPD and survival in non-small-cell lung cancer patients treated with cisplatin combination chemotherapy

ERCC1/BRCA1 expression and gene polymorphisms as prognostic and predictive factors in advanced NSCLC treated with or without cisplatin

Background:

The FAST was a factorial trial in first-line treatment of advanced non-small-cell lung cancer (NSCLC), addressing the role of replacing cisplatin with a non-platinum agent. The prognostic and predictive effect of ERCC1/BRCA1 expression and ERCC1/XPD/XRCC1–3 gene polymorphisms on outcomes of patients was examined.

Methods:

Patients were randomised to receive treatment with or without cisplatin. ERCC1/BRCA1 expression was determined by immunohistochemistry. ERCC1 (C8092A, C118T), XPD (Lys751Gln), XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) gene polymorphisms were evaluated on tumour DNA by TaqMan allelic discrimination assay.

Results:

Tumour samples were available from 110 of 433 patients enrolled: 54.7% were ERCC1 positive and 51.4% were BRCA1 positive. Overall, ERCC1-negative patients had better response rate (P=0.004), progression-free survival (P=0.023) and overall survival (P=0.012) compared with positive ones, with no statistically significant treatment interaction. The BRCA1-positive patients showed numerically better outcomes, although not statistically significant, with no treatment interaction. Among DNA repair gene polymorphisms, only XRCC1 Gln/Gln genotype evidenced a potential prognostic role (P=0.036).

Conclusion:

This study confirms the prognostic role of ERCC1 expression and XRCC1 (Arg399Gln) polymorphism in advanced NSCLC treated with first-line chemotherapy. None of these biomarkers was shown to be a specific predictive factor of cisplatin efficacy.

DNA repair and cytotoxic drugs: the potential role of RAD51 in clinical outcome of non-small-cell lung cancer patients

Many of the cytotoxic drugs used in the treatment of non-small-cell lung carcinoma patients can interfere with DNA activity and the definition of an individual DNA repair profile could be a key strategy to achieve better response to chemotherapeutic treatment. Although DNA repair mechanisms are important factors in the prevention of carcinogenesis, these molecular pathways are also involved in therapy response. RAD51 is a crucial element in DNA repair by homologous recombination and has been shown to interfere with the prognosis of patients treated with chemoradiotherapy. There is increasing evidence that genetic polymorphisms in repair enzymes can influence DNA repair capacity and, consequently, affect chemotherapy efficacy. We conducted this review to show the possible influence of the RAD51 genetic variants in damage repair capacity and treatment response in non-small-cell lung carcinoma patients.

Thymidylate synthase and ERCC1 as predictive markers in patients with pulmonary adenocarcinoma treated with pemetrexed and cisplatin

Increased expression of thymidylate synthase (TS) is thought to be associated with resistance to antifolate drugs such as pemetrexed. Excision repair cross-complementation group 1 (ERCC1) is a predictive marker for platinum-based chemotherapy. This study evaluated whether the expression of TS and ERCC1 proteins is associated with clinical outcomes of the patients with pulmonary adenocarcinoma who were treated with pemetrexed/cisplatin as first-line chemotherapy. The expressions of TS and ERCC1 were evaluated by immunohistochemistry in biopsy specimens obtained from patients with pulmonary adenocarcinoma who had received pemetrexed/cisplatin as first-line treatment. Patients were categorized according to median H-score. Response rate (RR), progression-free survival (PFS) and overall survival (OS) were analyzed retrospectively. Both low TS and ERCC1 expressions were significantly associated with better RR (p = 0.037 and p = 0.015, respectively) and longer PFS (p < 0.001 and p = 0.004, respectively). Low ERCC1 expression was also associated with longer OS (p = 0.003) while TS only showed a trend (p = 0.105). TS expression was independent predictor for the better PFS in multivariate analysis (hazard ratio [HR] = 0.32, 95% confidence interval [CI]: 0.14-0.76). Combining the two markers, the low TS/low ERCC1 group showed significantly longer PFS (HR = 0.48, 95% CI: 0.26-0.75) and OS (HR = 0.57, 95% CI: 0.36-0.89) compared with high TS/high ERCC1 group. Protein expressions of TS and ERCC1 were associated with clinical outcomes in patients with pulmonary adenocarcinoma who were treated with pemetrexed/cisplatin as first-line chemotherapy. TS and ERCC1 protein expressions can be potential predictive markers in this setting.

Predictive role of ERCC1 and XPD genetic polymorphisms in survival of Chinese non-small cell lung cancer patients receiving chemotherapy

AIM

There is increasing evidence that ERCC1 and XPD have roles in response to chemotherapy among patients with NSCLC, but the results are conflicting. Therefore, we conducted the present prospective study in a Chinese population.

METHODS

A total of 632 primary NSCLC patients were included, followed-up from May 2006 to May 2011. Polymorphisms were detected by real time PCR with TaqMan probse, using genomic DNA extracted from peripheral blood samples. The Cox regression model was used to analyze the hazard ratios (HR) for ERCC1 and XPD.

RESULTS

The median time of follow-up was 31.6 months. Our results showed the ERCC1 118 T/T(HR=1.65, 95% CI=1.17-2.43) and XPD 751 Gln/ Gln genotypes (HR=1.52, 95%CI=1.04-2.08) were associated with an increased risk of death from NSCLC. Moreover, the ERCC118 T allele and XPD 751 Gln allele genotypes had a more higher risk of death from NSCLC among both ex-smokers and current smokers.

CONCLUSION

In summary, ERCC1 and XPD gene polymorphisms might provide better prognostic predictive information for NSCLC patients in Chinese populations, with smoking possibly interacting with the genotypes.

Variants in nucleotide excision repair core genes and susceptibility to recurrence of squamous cell carcinoma of the oropharynx

Genetically determined capacity for NER may modulate both cancer risk and prognosis. Thus, we evaluated associations of seven selected variants in the NER core genes with recurrence risk in 658 squamous cell carcinoma of the oropharynx (SCCOP) patients treated principally by radiation. The seven polymorphisms in the core NER genes (XPC-rs2228000, XPC-rs2228001, XPD-rs1799793, XPD-rs13181, XPG-rs17655, ERCC1-rs3212986 and XPA-rs1800975) were genotyped using PCR-RFLP method and log-rank test and multivariable Cox models were used to evaluate the associations in both dominant and recessive genetic models. In a dominant model, we found that polymorphisms of XPC-rs2228000, XPD-rs1799793 and XPG-rs17655 were significantly associated with disease-free survival (log-rank, p = 0.014; p = 0.00008; p = 0.0007, respectively), and these polymorphisms were significantly associated with recurrence risk of SCCOP (hazard ratio (HR) = 1.6, 95% confidence interval (CI) 1.1-2.3 for XPC-rs2228000; HR = 0.4, 95% 0.3-0.6 for XPD-rs1799793 and HR = 0.5, 95% CI 0.4-0.8 for XPG-rs17655) after multivariable adjustment. Moreover, the borderline significant or significant associations were also found for these three polymorphisms in HPV16/18-positive SCCOP patients (HR = 1.6, 95% CI 1.0-4.1 for XPC-rs2228000; HR = 0.2, 95% CI 0.1-0.5 for XPD-rs1799793 and HR = 0.1, 95% CI 0.0-0.9 for XPG-rs17655). However, similarly significant associations were not found for these polymorphisms in a recessive model. These findings suggest that polymorphisms of XPC-rs2228000, XPD-rs1799793 and XPG-rs17655 in the NER core genes may contribute to recurrence risk of SCCOP, particularly HPV-positive SCCOP, in a dominant but not in a recessive model. However, validation of these results is warranted.

Phase II trial of bevacizumab and satraplatin in docetaxel-pretreated metastatic castrate-resistant prostate cancer

BACKGROUND

Satraplatin is an oral platinum compound that has demonstrated efficacy and tolerability in prostate cancer. Preclinical synergy between bevacizumab and platinum has been noted.

METHODS

Docetaxel-pretreated metastatic castrate-resistant prostate cancer patients with disease progression were eligible. Satraplatin 80 mg/m(2) orally on days 1 to 5, prednisone 5mg twice daily, and bevacizumab 10mg/kg on day 1, and 15 mg/kg on day 15 were administered in 35-day cycles.

RESULTS

Thirty one patients were enrolled. Grade 3 or 4 toxicities were pulmonary embolism in 2 patients and thrombocytopenia in 1 patient. 31% of the patients had a ≥ 30% decline in prostate-specific antigen. Median time to progression was 7.0 months (90% confidence interval [CI] 4.7-8.5mo) and median overall survival was 11.2 months (90% CI 9.1-16.4 mo). Polymorphism in the excision repair cross-complementation-1 (ERCC-1) gene was associated with time to progression (hazard ratio = 1.91). A circulating tumor cell count ≥ 5 was moderately prognostic of overall survival (hazard ratio = 1.49) as compared with CTC <5.

CONCLUSIONS

The combination was tolerable, and revealed promising efficacy in metastatic castrate-resistant prostate cancer. ERCC1 genotype maybe predictive of clinical benefit with platinum-based therapy in metastatic prostate cancer.

XRCC3 gene polymorphism is associated with survival in Japanese lung cancer patients

We focused on OGG1 Ser326Cys, MUTYH Gln324His, APEX1 Asp148Glu, XRCC1 Arg399Gln, and XRCC3 Thr241Met and examined the relationship between the different genotypes and survival of Japanese lung cancer patients. A total of 99 Japanese lung cancer patients were recruited into our study. Clinical data were collected, and genotypes of the target genes were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Survival analysis to verify the impact of these gene polymorphisms on the clinical outcome of lung cancer showed that lung squamous cell carcinoma patients with the Thr/Met genotype at XRCC3 had a significantly shorter survival time than those with the Thr/Thr genotype (13 months versus 48 months; log-rank test, p < 0.0001). Cox regression analysis showed that the carriers of XRCC3 genotypes were at a significantly higher risk [adjusted hazard ratio (HR) = 9.35, 95% confidence interval (CI) = 2.52-34.68, p = 0.001; adjusted HR = 9.05, 95% CI = 1.89-44.39, p = 0.006]. Our results suggest that XRCC3 Thr241Met may act as a favorable prognostic indicator for lung squamous cell carcinoma patients.

The A/G allele of eIF3a rs3740556 predicts platinum-based chemotherapy resistance in lung cancer patients

eIF3a is the largest subunit of eukaryotic translation initiation factor 3, which has been suggested to affect tumor progression and activity of nucleotide excision repair pathway contributing to platinum resistance. The purpose of this study was to investigate possible mutations in promoter and exon regions of eIF3a gene and to assess whether eIF3a mutation status have prognostic and predictive significance in platinum-based chemotherapeutic lung cancer patients. 771 lung cancer patients were enrolled and followed up. These patients were newly diagnosed with incident lung cancer, which was confirmed histologically or cytologically, and accepted platinum-based chemotherapy for at least two cycles. Three novel mutations of eIF3a were found, including 11279G>A in intron 6, Arg438Lys in exon 9, 29671G>A in intron 15, with minor allele frequency of 0.16, 0.18, 0.16, respectively. A-carrier patients of rs3740556 conferred a significantly better platinum-based chemotherapy response (p < 0.05) and seemed to live longer. eIF3a genetic polymorphisms can be considered as predictive tools for pretreatment evaluation of platinum-based chemotherapy. Lung cancer patients carrying rs3740556 A allele tended to have a favorable prognosis after treatment with platinum-based chemotherapy.

Association of ERCC1 SNPs with outcome in platinum-treated patients with advanced urothelial cancer: a Hellenic Cooperative Oncology Group study

Aim: The association between two polymorphisms of ERCC1 and treatment outcomes after platinum-based chemotherapy in patients with advanced urothelial cancer (UC) was examined. Materials & methods: Genotyping of 19007C>T and 8092C>A polymorphisms was determined by PCR amplification and RFLP in 113 advanced UC patients, treated with platinum-based chemotherapy. Results: Seventy eight patients (69%) were carriers of the 19007T polymorphic allele: 51 (45%) heterozygotes and 27 (24%) homozygotes. Fifty three (47%) patients were carriers of the 8092A polymorphic allele: the frequencies of C/A and A/A genotypes were 37% and 10%, respectively. The T/T genotype was independently associated with prolonged median cancer-specific survival (not-reached vs 14.8 months; p = 0.026). There was no interaction between T/T or any other genotype with the type of platinum derivative (cisplatin/carboplatin). Conclusion: 19007C>T, especially in its homozygotic state, but not 8092C>A polymorphism, could be a useful prognostic marker in advanced UC treated with platinum-based chemotherapy.

Original submitted 17 July 2012; Revision submitted 21 September 2012

Genetic polymorphism of XRCC1 Arg399Gln is associated with survival in non-small-cell lung cancer patients treated with gemcitabine/platinum

INTRODUCTION

Elevated DNA-repair capacity has been related to chemoresistance of platinum doublet chemotherapy in non-small-cell lung cancer (NSCLC). We evaluated whether single nucleotide polymorphisms of DN- repair genes excision repair cross-complementing group 1 (ERCC1), ERCC2, x-ray repair cross-complementing group 1 (XRCC1), XRCC3, and RRM1 associate with treatment outcome in NSCLC patients receiving gemcitabine plus platinum as their first-line chemotherapy.

METHODS

Genotyping for eight polymorphisms in five DNA-repair genes was performed with the GenomeLab nucleotide polymorphismstream Genotyping System in 62 advanced NSCLC patients in a training set and 45 patients in a validation set treated with gemcitabine/platinum.

RESULTS

In the training set, the wild-type genotype of XRCC1 Arg399Gln (G/G) was associated with decreased median overall survival (OS) (22 months, 95% confidence interval [CI], 10-34 months versus not reached, log-rank test, p = 0.005) than those carrying variant genotypes (G/A+A/A). In addition, there was a statistically significant longer median OS in patients carrying wild-type ERCC2 Asp312Asn genotype (G/G) (51 months, 95% CI, 19-82 months versus 10 months, log-rank test, p < 0.001) than those carrying heterozygous variant genotypes (G/A). In the multivariate Cox model, we found a significant effect of XRCC1 Arg399Gln (G/A+A/A versus G/G, hazard ratio [HR] 0.290; 95%CI, 0.12-0.705, p = 0.006) and ERCC2 Asp312Asn (G/A versus G/G, HR 14.04; 95% CI, 2.253-87.513, p = 0.005) polymorphisms on patients' OS. In the validation set, only XRCC1 399

CONCLUSIONS

Genetic polymorphism of XRCC1 Arg399Gln may be a candidate for contributing interindividual difference in the OS of gemcitabine/platinum-treated advanced NSCLC patients.

Genetic variants in genes involved in mechanisms of chemoresistance to anticancer drugs

Refractoriness to the pharmacological treatment of cancer is dependent on the expression levels of genes involved in mechanisms of chemoresistance and on the existence of genetic variants that may affect their function. Thus, changes in genes encoding solute carriers may account for considerable inter-individual variability in drug uptake and the lack of sensitivity to the substrates of these transporters. Moreover, changes in proteins involved in drug export can affect their subcellular localization and transport ability and hence may also modify the bioavailability of antitumor agents. Regarding pro-drug activation or drug inactivation, genetic variants are responsible for changes in the activity of drug-metabolizing enzymes, which affect drug clearance and may determine the lack of response to anticancer chemotherapy. The presence of genetic variants may also decrease the sensitivity to pharmacological agents acting through molecular targets or signaling pathways. Recent investigations suggest that changes in genes involved in DNA repair may affect the response to platinum-based drugs. Since most anticancer agents activate cell death pathways, the evasion of apoptosis plays an important role in chemoresistance. Several genetic variants affecting death-receptor pathways, the mitochondrial pathway, downstream caspases and their natural modulators, and the p53 pathway, whose elements are mutated in more than half of tumors, and survival pathways, have been reported. The present review summarizes the available data regarding the role of genetic variants in the different mechanisms of chemoresistance and discusses their potential impact in clinical practice and in the development of tools to predict and overcome chemoresistance.

Polymorphisms of ERCC1 genotype associated with response to imatinib therapy in chronic phase chronic myeloid leukemia

DNA repair machinery may contribute to the mechanism of the action in imatinib. We examined the association between the single nucleotide polymorphism (SNP) markers involved in the DNA repair enzyme pathway (ERCC1/2/4/5, XRCC1/2/4/5) and the clinical outcomes following an imatinib therapy in chronic phase chronic myeloid leukemia (CML) patients. A total of 169 Korean patients were included. Of the 19 SNPs from these patients, those with the TT genotype of ERCC1 (rs11615) showed a higher probability of achieving major cytogenetic response [P = 0.002, HR 5.14 (95 % CI 1.83-14.43)], complete cytogenetic response [P = 0.012, HR 3.47 (95 % CI 1.31-9.17)], and major molecular response [P = 0.001, HR 5.71 (95 % CI 2.13-15.30)] than those with CC or CT genotypes. This suggests that SNP markers on ERCC1 may predict the response to imatinib therapy, which proposes the potential involvement of the DNA repair machinery in the mechanism of imatinib action in chronic phase CML.

Meta-analysis on pharmacogenetics of platinum-based chemotherapy in non small cell lung cancer (NSCLC) patients

AIM

To determine the pharmacogenetics of platinum-based chemotherapy in Non Small Cell Lung Cancer (NSCLC) patients.

METHODS

Publications were selected from PubMed, Cochrane Library and ISI Web of Knowledge. A meta-analysis was conducted to determine the association between genetic polymorphisms and platinum-based chemotherapy by checking odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Data were extracted from 24 publications, which included 11 polymorphisms in 8 genes for meta-analysis. MDR1 C3435T (OR = 1.97, 95% CI: 1.11-3.50, P = 0.02), G2677A/T (OR = 2.61, 95% CI: 1.44-4.74, P = 0.002) and GSTP1 A313G (OR = 0.32, 95% CI: 0.17-0.58, P = 0.0002) were significantly correlated with platinum-based chemotherapy in Asian NSCLC patients.

CONCLUSION

Attention should be paid to MDR1 C3435T, G2677A/T and GSTP1 A313G for personalized chemotherapy treatment for NSCLC patients in Asian population in the future.

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.

Role of the RAD51 G172T polymorphism in the clinical outcome of cervical cancer patients under concomitant chemoradiotherapy

INTRODUCTION

Cervical cancer is one of the most common cancers diagnosed in women worldwide. Mammalian cells are constantly exposed to a wide variety of genotoxic agents from both endogenous and exogenous sources. The RAD51 protein is required for meiotic and mitotic recombination and plays a central role in homology-dependent recombinational repair of double-strand breaks (DSBs). Given the functional relevance of the DNA repair system on carcinogenesis, potential associations between genetic polymorphisms of DNA repair genes, cancer risk and response to therapy have been intensively evaluated. This is the first study evaluating the role of the RAD51 G172T genetic variants in cancer prognosis and clinical outcome of cervical cancer patients.

MATERIAL AND METHODS

We analyzed RAD51 G172T polymorphism genotypes in cervical cancer patients who underwent a platinum-based chemotherapy in combination with radiotherapy. Genotyping was performed by Taqman™ Allelic Discrimination methodology.

RESULTS AND DISCUSSION

Concerning the overall survival rates found using Kaplan-Meier method and Log Rank Test, we observed that the mean survival rates were statistically different according to the patients RAD51 genotypes. The group of patients carrying the T allele present a higher mean survival rate than the other patients (102.3months vs. 86.4months, P=0.020). Using the Cox regression analysis, we found an increased overall survival time for T-carrier patients, when compared with GG genotype, with tumor stage, age and presence of lymph nodes as covariates [hazard ratio (HR), 0.373; 95% CI, 0.181-0.770; P=0.008]. Among patients (n=193), RAD51 genotype frequency distributions were not under the influence of clinicopathologic characteristics, namely, treatment response (P=0.508), recurrence (P=0.150) and tumor stage (P=0.250).

CONCLUSIONS

This is the first study evaluating the role of the RAD51 G172T genetic variants in cancer prognosis and clinical outcome of cervical cancer patients. Our results indicate an influence of the RAD51 genetic variants in overall survival of cervical cancer. Thereby, RAD51 G172T genotypes may provide additional prognostic information in cervical cancer patients who underwent cisplatin-based chemotherapy in combination with radiotherapy.

Association of cytidine deaminase and xeroderma pigmentosum group D polymorphisms with response, toxicity, and survival in cisplatin/gemcitabine-treated advanced non-small cell lung cancer patients

BACKGROUND

Selecting patients according to key genetic characteristics may help to tailor chemotherapy and optimize the treatment in non-small cell lung cancer (NSCLC). Genetic variations in drug metabolism may affect the clinical response, toxicity, and prognosis of NSCLC patients treated with cisplatin/gemcitabine-based therapy.

PATIENTS AND METHODS

We evaluated seven single-nucleotide polymorphisms of six genes CDA Lys27Gln (A/C); CDA C435T; ERCC1 C118T; XRCC3 Thr241Met (C/T); XPD Lys751Gln (A/C); P53 Arg72Pro (G/C), and RRM1 C524T in 192 chemotherapy-naive patients with advanced NSCLC treated with cisplatin/gemcitabine-based regimen by TaqMan probe-based assays with 7300 Real-Time PCR System, using genomic DNA extracted from blood samples.

RESULTS

The CDA 435 T/T genotype was significantly associated with better response (p = 0.03). The CDA 435 C/T genotype was associated with a significantly increased risk of nonhematological toxicity of grade ≥3 (p = 0.02) after adjusting for performance status, age, and type of treatment regimen. In the multivariate Cox model, the XPD 751 C/C genotype was a significant prognostic factor of longer progression-free survival (p = 0.006).

CONCLUSION

Our data suggest polymorphic variations of drug metabolic gene were associated with response and toxicity of cisplatin/gemcitabine-based therapy and progression-free survival of patients with advanced NSCLC.

Identification of Nkx2-3 and TGFB1I1 expression levels as potential biomarkers to predict the effects of FOLFOX4 chemotherapy

This study was designed to detect global gene expressions of primary advanced colorectal cancer (ACC) patients who have undergone FOLFOX4 chemotherapy and screen valuable biomarkers to predict the effects of chemotherapy. Samples from primary ACC patients who have undergone FOLFOX4 chemotherapy were collected. Their chemotherapy effects were evaluated and divided into chemotherapy sensitive group (experimental group) and non-sensitive group (control group). Cancerous tissue gene expression profiles were detected by chip technology. Two groups with differentially expressed genes were screened by cluster analysis and significance analysis of microarrays (SAM). Valuable biomarkers were screened by bioinformatics analysis. Immunohistochemical analysis was performed to characterize the pattern of Nkx2-3 and TGFB1I1 expression. Nkx2-3 and TGFB1I1 signal log ratio were used Receiver Operating Characteristic (ROC) analyses to calculate its own predicting accuracy. Thirty cases were divided into experimental group (13 cases) and control group (17 cases). There was evident difference in the tumor cell biology states of the two groups; that is, 25 ESTs (21 genes) were upregulated and 5 ESTs (5 genes) were downregulated. Nkx2-3 protein was observed on the nucleus of the cancer cells and TGFB1I1 protein was observed on the nucleus and cytoplasm of the cancer cells in experimental group. Their prediction accuracies were 85.3% and 76.7% respectively. Nkx2-3 and TGFB1I1 expressions in control group are very low, but highly expressed in the experimental group; Nkx2-3 and TGFB1I1 may be classified as valuable biomarkers, as these can predict the effects of primary ACC patients who will undergo FOLFOX4.

Effect of polymorphisms in XPD on clinical outcomes of platinum-based chemotherapy for Chinese non-small cell lung cancer patients

PURPOSE

Xeroderma pigmentosum group D (XPD) codes for a DNA helicase involved in nucleotide excision repair that removes platinum-induced DNA damage. Genetic polymorphisms of XPD may affect DNA repair capacity and lead to individual differences in the outcome of patients after chemotherapy. This study aims to identify whether XPD polymorphisms affect clinical efficacy among advanced non-small cell lung cancer (NSCLC) patients treated with platinum-based chemotherapy.

EXPERIMENTAL DESIGN

353 stage III-IV NSCLC patients receiving platinum-based chemotherapy as the first-line treatment were enrolled in this study. Four potentially functional XPD polymorphisms (Arg(156)Arg, Asp(312)Asn, Asp(711)Asp and Lys(751)Gln) were genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or PCR-based sequencing.

RESULTS

Variant genotypes of XPD Asp(312)Asn, Asp(711)Asp and Lys(751)Gln were significantly associated with poorer NSCLC survival (P = 0.006, 0.006, 0.014, respectively, by log-rank test). The most common haplotype GCA (in order of Asp(312)Asn, Asp(711)Asp and Lys(751)Gln) also exhibited significant risk effect on NSCLC survival (log-rank P = 0.001). This effect was more predominant for patients with stage IIIB disease (P = 2.21×10(-4), log-rank test). Increased risks for variant haplotypes of XPD were also observed among patients with performance status of 0-1 and patients with adenocarcinoma. However, no significant associations were found between these polymorphisms, chemotherapy response and PFS.

CONCLUSIONS

Our study provides evidence for the predictive role of XPD Asp(312)Asn, Asp(711)Asp and Lys(751)Gln polymorphisms/haplotype on NSCLC prognosis in inoperable advanced NSCLC patients treated with platinum-based chemotherapy.

Disease-free survival of patients after surgical resection of non-small cell lung carcinoma and correlation with excision repair cross-complementation group 1 expression and genotype

BACKGROUND AND OBJECTIVE

Expression of excision repair cross-complementation group 1 (ERCC1) is recognized as a favourable prognostic marker in patients who have undergone surgical resection of non-small cell lung cancer (NSCLC). However, in patients treated with adjuvant chemotherapy after surgical resection, ERCC1 correlated with poor prognosis. Class III beta tubulin (TUBB3) is also known to be a predictive marker of the efficacy of treatment with taxanes or vinorelbine.

METHODS

Tumour tissues (n = 363) from patients with surgically resected NSCLC were analysed retrospectively. Tissue sections were labelled with ERCC1- and TUBB3-specific antibodies. Using genomic DNA from 262 patients, single nucleotide polymorphisms of the ERCC1 gene (T19007C and C8092A) were genotyped by PCR-restriction fragment length polymorphism analysis.

RESULTS

Only 5.9% of patients with stage I disease (14/238) and 61.6% of patients with stages II-III disease (77/125) received adjuvant chemotherapy. Relapses were noted in 30.6% (111) of patients, and among these, 31 ultimately succumbed. The relapse rate (RR) was 24.8% for stage I disease, and 41.6% for stages II-III disease. The RR was significantly lower in ERCC1-positive (24.3%) as compared with ERCC1-negative patients (36.3%, P = 0.014) and was lower in patients with the AA/CA genotype at the ERCC1 C8092A locus (29.5%) compared with those with the CC genotype (42.1%, P = 0.034). The median disease-free survival (DFS) time was 62.3 months. DFS was significantly greater in ERCC1-positive patients (62.3 months) than in ERCC1-negative patients (48.0 months, P = 0.042). In a multivariate analysis, ERCC1 expression and the C8092A polymorphism were independent prognostic factors in patients with stage I disease who were naïve to chemotherapy.

CONCLUSIONS

ERCC1 expression and the AA/CA genotype at the C8092A locus were correlated with a good prognosis in patients who had undergone surgical resection of NSCLC.

Response to gemcitabine-platinum chemotherapy by single nucleotide polymorphisms of RRM1 and ERCC1 genes in patients with non-small-cell lung cancer

BACKGROUND

  RRM1, the regulatory subunit of ribonucleotide reductase, is involved in carcinogenesis and the response to gemcitabine. Two single nucleotide polymorphisms (SNP) in the RRM1 gene (RR37 and RR524) impact promoter activity and are associated with prognosis. The excision repair cross-complementation group 1 protein (ERCC1) is associated with platinum resistance. A SNP of the ERCC1 gene (T19007C) has been reported as a prognostic marker in platinum-treated non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

  Patients with stage IIIB or IV NSCLC were treated with gemcitabine and platinum (GP) as first-line chemotherapy. Adenocarcinoma was the most frequent histological type, followed by squamous cell carcinoma and then other types. SNP were analyzed with real time-polymerase chain reaction using genomic DNA extracted from peripheral blood.

RESULTS

  Based on responses to GP patients were classified as responders or non-responders. The response rate was significantly higher in patients with the RR AC-CT genotype (35/64, 54.7%) compared to those with the RR CC-TT genotype (56/147, 38.1%, P= 0.025). No significant difference in response rate was observed according to ERCC1 genotype. In 128 patients with non-squamous cell lung cancer, RR AC-CT + ERCC1 CC (63.2%) and RR AC-CT + ERCC1 CT/TT (61.9%) showed higher response rates compared to RR CC-TT + ERCC1 CC (36.5%), and RR CC-TT + ERCC1 CT/TT (22.2%; P= 0.004). Progression-free and overall survival times were not different between genotypes.

CONCLUSIONS

  We observed significantly different responses to the GP regimen according to SNP of the RRM1 and ERCC1 genes.

Genetic variations in multiple drug action pathways and survival in advanced stage non-small cell lung cancer treated with chemotherapy

PURPOSE

Variations in genes related to biological activity of anticancer drugs could influence treatment responses and lung cancer prognosis. Genetic variants in four biological pathways, that is, glutathione metabolism, DNA repair, cell cycle, and epidermal growth factor receptor (EGFR), were systematically investigated to examine their association with survival in advanced stage non-small cell lung cancer (NSCLC) treated with chemotherapy.

EXPERIMENTAL DESIGN

A total of 894 tagging single-nucleotide polymorphisms (SNP) in 70 genes from the four pathways were genotyped and analyzed in a 1,076-patient cohort. Association with overall survival was analyzed at SNP and whole-gene levels within all patients and major chemotherapy agent combination groups.

RESULTS

A poorer overall survival was observed in patients with genetic variations in GSS (glutathione pathway) and MAP3K1 (EGFR pathway; HR = 1.45; 95% CI = 1.20-1.77 and HR = 1.25; 95% CI = 1.05-1.50, respectively). In the stratified analysis on patients receiving platinum plus taxane treatment, we observed a hazardous effect on overall survival by the MAP3K1 variant (HR = 1.38; 95% CI = 1.11-1.72) and a protective effect by RAF1 (HR = 0.64; 95% CI = 0.50-0.82) in the EGFR pathway. In patients receiving platinum plus gemcitabine treatment, RAF1 and GPX5 (glutathione pathway) genetic variations showed protective effects on survival (HR = 0.54; 95% CI = 0.38-0.77; HR = 0.67; 95% CI = 0.52-0.85, respectively); in contrast, NRAS (EGFR pathway) and GPX7 (glutathione pathway) variations showed hazardous effects on overall survival (HR = 1.91; 95% CI = 1.30-2.80; HR = 1.83; 95% CI = 1.27-2.63, respectively). All genes that harbored these significant SNPs remained significant by whole-gene analysis.

CONCLUSION

Common genetic variations in genes of EGFR and glutathione pathways may be associated with overall survival among patients with advanced stage NSCLC treated with platinum, taxane, and/or gemicitabine combinations.

Pharmacogenomics of cisplatin-based chemotherapy in ovarian cancer patients of different ethnic origins

AIM

There is a substantial difference between Asians and Caucasians in their reaction to platinum drugs. To determine whether population-related genomics contribute to differences in patient outcomes, pharmacogenomic relevance of polymorphisms in some genes, the protein activities of which may affect aspects of cisplatin metabolism, were evaluated.

PATIENTS & METHODS

Nineteen polymorphisms in ten genes were tested for correlations with the efficacy and toxicity of a cisplatin-cyclophosphamide regimen in Yakut and Russian patients with ovarian cancer.

RESULTS

The CYP2E1 7632T>A polymorphism was associated with progression-free survival (p = 0.015) in Yakuts. In Russians, progression-free survival was correlated with the GSTP1 Ile105Val polymorphism (p = 0.004). Yakut patients with the GSTT1-null genotype had a higher risk for nephrotoxicity. By contrast, in the Russian group, nephrotoxicity was more frequent among patients with heterozygous ERCC1 genotypes. Severe emesis in Yakuts was independently associated with two polymorphisms in the CYP2E1 gene but in Russians, it was more common in patients with the GSTT1-null genotype. Differences in genotypic correlations with anemia were also observed.

CONCLUSION

Significant differences in genotype distribution between Russian and Yakut women were observed for ten of the 19 polymorphisms, but none of them seemed to be a clear casual candidate and further studies involving more markers are required.

Predictive role of XRCC5/XRCC6 genotypes in digestive system cancers

Cancers are a worldwide concern; oral, esophageal and gastrointestinal cancers represent important causes of cancer-related mortality and contribute to a significant burden of human health. The DNA repair systems are the genome caretakers, playing a critical role in the initiation and progression of cancers. However, the association between the genomic variations of DNA repair genes and cancer susceptibility is not well understood. This review focuses on the polymorphic genotypes of the non-homologous end-joining DNA repair system, highlighting the role of two genes of this pathway, XRCC5 and XRCC6, in the susceptibility to digestive system cancers and discussing their potential contributions to personalized medicine.

Single nucleotide polymorphisms in MDR1 gen correlates with outcome in advanced non-small-cell lung cancer patients treated with cisplatin plus vinorelbine

New therapeutic approaches are being developed based on the findings that several genetic abnormalities underlying NSCLC could influence chemosensitivity. In this study, we assessed whether the presence of polymorphisms in ERCC1, XPD, RRM1 and MDR1 genes can affect the efficacy and the tolerability of cisplatin and vinorelbine in NSCLC patients.

MATERIAL AND METHODS

Eligible patients had histological confirmed stage IV or IIIB (with malignant pleural effusion) non-small-cell lung cancer (NSCLC) previously untreated with chemotherapy; World Health Organization performance status (PS) 0-1. Patients received intravenous doses of vinorelbine 25 mg/m² on day 1 and 8 and cisplatin 75 mg/m² on day 1, every 21 days, for a maximum of eight cycles.

RESULTS

94 patients were included. Median age was 61 years; 84% were male; WHO performance status (PS) was 0 in 24%; and 88% of patients had stage IV disease. The median number of cycles was 6. Overall median survival was 10.92 months (95% CI 9.0-12.9). Overall median time to progression was 5.89 months (95% CI 5.2-6.6). Results of the multivariate analysis for time to progression showed that ECOG 0 (hazard ratio [HR] ECOG 1 vs. ECOG 0, 1.74; p=0.036), MDR13435CC (HR CT vs. CC, 2.01; p=0.017; HR TT vs. CC, 1.54; p=0.22), and decreasing age (HR of age, 0.97; p=0.016) were the most powerful prognostic factors significantly related to lower risk of progression. Whereas ECOG 0 was the only prognostic factor for survival (HR ECOG 1 vs. ECOG 0, 3.02; p=0.001). There was no significant association between any of the SNPs analysed and the occurrence of vinorelbine and cisplatin-related toxicity.

CONCLUSION

In our results, the most important prognostic factors associated with lower risk of progression were MDR1 3435 CC genotype, PS 0 and younger age.

Role of DNA repair gene polymorphisms in the efficiency of platinum-based adjuvant chemotherapy for non-small cell lung cancer

BACKGROUND

Cisplatin-based adjuvant treatment of non-small cell lung cancer (NSCLC) has become standard, thanks to the studies that have shown a significant survival advantage. The identification of patients who could benefit from this adjuvant treatment would allow ineffective and toxic administrations to be avoided. Immunohistochemical expression of the excision repair cross-complementation group (ERCC)-1 protein has been associated with response to platinum-based chemotherapy in patients with NSCLC, and some polymorphisms of the genes involved in DNA repair have been shown to be associated with survival in advanced NSCLC.

OBJECTIVE

The aim of our study was to evaluate the progression-free survival and tolerability of adjuvant treatment with platinum-based chemotherapy in patients with NSCLC, according to common DNA repair gene polymorphisms and ERCC1 expression.

METHODS

We investigated the association of three DNA repair gene polymorphisms - Asn118Asn in ERCC1 (rs11615), Lys751Gln in ERCC2 (rs13181), and Asp1104His in ERCC5 (rs17655) - with the progression-free survival of 85 patients treated with platinum-based chemotherapy after surgery for NSCLC.

RESULTS

We did not find significant associations between any of these polymorphisms and progression-free survival, nor did we observe any difference in progression-free survival according to ERCC1 expression.

CONCLUSION

The previously reported impact of DNA repair gene polymorphisms on platinum-based chemotherapy treatment of advanced NSCLC was not observed in our study in the adjuvant setting.

Association between DNA-repair polymorphisms and survival in pancreatic cancer patients treated with combination chemotherapy

AIM

This multicenter study evaluated the association of 11 candidate polymorphisms in eight genes with outcome of pancreatic cancer patients treated with the equivalent polychemotherapeutic regimens: cisplatin/epirubicin/capecitabine/gemcitabine, cisplatin/docetaxel/capecitabine/gemcitabine and gemcitabine/capecitabine plus epirubicin/cisplatin intra-arterial infusion.

PATIENTS & METHODS

Towards this end, polymorphisms were assessed in DNA from 122 pancreatic cancer stage-III/IV patients, and their associations with toxicity/response and progression-free survival (PFS) and overall survival were evaluated using Pearson-χ(2) and log-rank test.

RESULTS

Patients harboring XPD Gln751Gln, XPD Asp312Asn + Asn312Asn or XRCC1 Arg399Gln + Gln399Gln genotypes had a worse prognosis. XPD Gln751Gln (hazard ratio: 1.9; p = 0.003), as well as a combination of over two risk genotypes (hazard ratio: 2.7; p < 0.001), emerged as independent predictors for death risk at multivariate analysis. No correlations were observed with toxicity. Conversely, XPD Gln751Gln was associated with shorter PFS, while the lack of association with overall survival/PFS in gemcitabine monotherapy-treated patients suggested its role only for platinum-based regimens.

CONCLUSION

Polymorphisms of DNA-repair genes appear to be candidate biomarkers of primary resistance to gemcitabine/cisplatin-based polychemotherapeutic regimens. The relatively small sample size, coupled with the retrospective and exploratory design of the present study, imply that these results should be considered as hypothesis generators, and should be further evaluated in larger and adequately designed retrospective/prospective studies.

Pharmacogenetic analyses of cisplatin-induced nephrotoxicity indicate a renoprotective effect of ERCC1 polymorphisms

AIM

We investigated whether genetic polymorphisms may contribute to the interpatient variability of cisplatin-induced nephrotoxicity.

PATIENTS & METHODS

Polymorphisms in the candidate genes GSTM1, GSTT1, OCT1, OCT2, LARP2, ERCC1, XRCC1 and EPO were analyzed for associations with nephrotoxicity in 79 cancer patients receiving cisplatin-containing chemotherapy.

RESULTS

Higher cisplatin dose was associated with strongly decreased estimated glomerular filtration rates (eGFR) (r(2) = 0.205). Two highly genetically linked polymorphisms in the ERCC1 gene, 8092C>A and Asn118Asn, were significantly associated with change in eGFR, accounting for an additional 13% of interindividual variability. Homozygous carriers of the 8092A allele in ERCC1 showed no reduction in eGFR, compared with the 11.5% mean eGFR decrease in C allele carriers (p = 0.004). Homozygous carriers of the C allele of Asn118Asn showed no reduction in eGFR, compared with the 12.8% mean eGFR decrease seen in T allele carriers (p = 0.047). Polymorphisms in the other candidate genes were not associated with cisplatin-induced nephrotoxicity.

CONCLUSION

Genetic polymorphisms in ERCC1 may be valuable predictors of cisplatin-induced nephrotoxicity.

Polymorphisms of ERCC1 C118T/C8092A and MDR1 C3435T predict outcome of platinum-based chemotherapies in advanced non-small cell lung cancer: a meta-analysis

BACKGROUND AND AIMS

With great progress made in individualized chemotherapy, pharmacogenetics is gradually put on the agenda. We performed this meta-analysis to compare outcome to platinum-based chemotherapies in advanced non-small cell lung cancer (NSCLC) with different ERCC1 C118T/C8092A and MDR1 C3435T polymorphisms.

METHODS

Relevant studies were identified according to search strategy in this meta-analysis. Inclusion criteria were patients with advanced NSCLC who were receiving platinum-based chemotherapies. We evaluated the relationship between single nucleotide polymorphisms (SNP) and outcome of platinum-based chemotherapies. RevMan and STATA package were used for the comprehensive quantitative analyses.

RESULTS

Twenty studies were included in the meta-analysis. There was no significant association between SNPs and objective response or overall survival of platinum-based chemotherapies with CC vs. CT/TT: ERCC1 C118T (OR 1.21, 95% CI 0.81-1.82 for objective response; HR 1.09, 95% CI 0.79-1.51 for overall survival); ERCC1 C8092A SNP (OR 0.84, 95% CI 0.59-1.18; HR 1.26, 95% CI 0.68-2.36) and MDR1 C3435T SNP (HR 1.11, 95% CI 0.78-1.56). Ethnic stratification provided the same results. We found a significant difference for MDR1 C3435T (OR 2.22, 95% CI 1.46-3.37; OR 2.63, 95% CI 1.56-4.45 for Asians; OR 1.61, 95% CI 0.79-3.28 for Caucasians).

CONCLUSIONS

We found no evidence to support the use of ERCC1 C118T/C8092A polymorphisms as prognostic predictors of platinum-based chemotherapies in NSCLC. For the MDR1 C3435T SNP, a significant association with objective response was detected for CC genotype in overall and Asian populations stratified. Multiple and large-scale studies with ethnic stratification are required for the correlation between biomarkers and tumor prognosis.

ERCC1 and XRCC1 as biomarkers for lung and head and neck cancer

Advanced stage non-small cell lung cancer and head and neck squamous cell carcinoma are both treated with DNA damaging agents including platinum-based compounds and radiation therapy. However, at least one quarter of all tumors are resistant or refractory to these genotoxic agents. Yet the agents are extremely toxic, leading to undesirable side effects with potentially no benefit. Alternative therapies exist, but currently there are no tools to predict whether the first-line genotoxic agents will work in any given patient. To maximize therapeutic success and limit unnecessary toxicity, emerging clinical trials aim to inform personalized treatments tailored to the biology of individual tumors. Worldwide, significant resources have been invested in identifying biomarkers for guiding the treatment of lung and head and neck cancer. DNA repair proteins of the nucleotide excision repair pathway (ERCC1) and of the base excision repair pathway (XRCC1), which are instrumental in clearing DNA damage caused by platinum drugs and radiation, have been extensively studied as potential biomarkers of clinical outcomes in lung and head and neck cancers. The results are complex and contradictory. Here we summarize the current status of single nucleotide polymorphisms, mRNA, and protein expression of ERCC1 and XRCC1 in relation to cancer risk and patient outcomes.

Potentially functional polymorphisms in DNA repair genes and non-small-cell lung cancer survival: a pathway-based analysis

To assess systematically whether potentially functional polymorphisms in DNA repair genes influence the clinical behavior of non-small-cell lung cancer (NSCLC), we examined the impact of a comprehensive panel of 218 signal nucleotide polymorphisms (SNP) in 50 candidate DNA repair genes on overall survival of NSCLC in a case-cohort of 568 lung cancer patients. SNPs associated with lung cancer prognosis primarily mapped to 14 genes in different repair pathways, and 6 SNPs were remained in the final model after multivariate stepwise Cox regression analysis: ATM rs189037; MRE11A rs11020802; ERCC2 rs1799793; MBD4 rs140693; XRCC1 rs25487, and PMS1 rs5742933. In the combined analysis of these 6 SNPs, an increasing number of unfavorable loci was associated with a poorer prognosis (P for trend: <0.0001) and patients having 2-4 unfavorable loci had a 1.99-fold elevated risk of death 95% confidence interval (CI) = 1.58-2.50, compared with those carrying 0-1 unfavorable loci, and this elevated risk was more evident among stages I-II patients (hazard ratio = 3.04, 95% CI = 1.86-4.98, P for heterogeneity: 0.07). Furthermore, a significant effect of SNPs in nucleotide excision repair pathway on lung cancer survival was observed among 185 stages III-IV patients treated with platinum-based chemotherapy without surgical operation: XPC rs2228000 (Ala499Val; P = 0.002) and ERCC1 rs11615 (Asn118Asn; P = 0.012). Our data indicate that potentially functional polymorphisms in DNA repair genes may serve as candidate prognostic markers of clinical outcome of NSCLC.

Association between polymorphisms of DNA repair genes and survival of advanced NSCLC patients treated with platinum-based chemotherapy

BACKGROUND

Single nucleotide polymorphism (SNP) in DNA repair genes can be used to explain the differences in survival of platinum-treated non-small cell lung cancer (NSCLC) patients regardless of their performance status. To define the role of DNA repair gene SNPs in NSCLC patients, we investigated the association between survival and 12 different SNPs of 9 DNA repair genes.

METHODS

340 patients were treated with platinum-based chemotherapy. Polymorphisms were detected by real time PCR with TaqMan probe, using genomic DNA extracted from peripheral blood samples. Multivariate logistic or Cox regression analyses were used to adjust for possible confounding variables.

RESULTS

The median overall survival time was 15 months and it was significantly longer in patients harboring ERCC1 118 C/T or T/T allele: 18 months as compared to 13.8 months for the C/C allele (P=0.014). Subgroup analysis revealed that ERCC1 118 C/T or T/T was associated with increased survival in elderly patients (P=0.018), male (P=0.022), squamous carcinoma (P=0.003), smoker (P=0.076) and those treated with non-gemcitabine/cisplatin or carboplatin (non-GP/GC) regimen (P=0.023). XRCC3C/C was associated with better survival in non-gemcitabine/cisplatin treated patients (P=0.014). Both of CCNH-V270A C/C or C/T and XPD 751 A/A showed a significant longer survival in the squamous cell carcinoma subgroup (P=0.047 and P=0.034 respectively).

CONCLUSION

Present data indicates that ERCC1 118 C/T or T/T might provide a better prognostic predictive marker of NSCLC patients treated with platinum-based chemotherapy, mainly in elderly subgroup, male, squamous carcinoma, smoker and those treated with non-GP/GC regimen.

Part 4: pharmacogenetic variability in anticancer pharmacodynamic drug effects

Response to treatment with anticancer drugs is subject to wide interindividual variability. This variability is expressed not only as differences in severity and type of toxicity, but also as differences in effectiveness. Variability in the constitution of genes involved in the pharmacokinetic and pharmacodynamic pathways of anticancer drugs has been shown to possibly translate into differences in treatment outcome. The overall knowledge in the field of pharmacogenetics has tremendously increased over the last couple of years, and has thereby provided opportunities for patient-tailored anticancer therapy. In previous parts of this series, we described pharmacogenetic variability in anticancer phase I and phase II drug metabolism and drug transport. This fourth part of a four-part series of reviews is focused on pharmacodynamic variability and encompasses genetic variation in drug target genes such as those encoding thymidylate synthase, methylene tetrahydrofolate reductase, and ribonucleotide reductase. Furthermore, genetic variability in other pharmacodynamic candidate genes involved in response to anticancer drugs is discussed, including genes involved in DNA repair such as those encoding excision repair crosscomplementing group 1 and group 2, x-ray crosscomplementing group 1 and group 3, and breast cancer genes 1 and 2. Finally, somatic mutations in KRAS and the gene encoding epidermal growth factor receptor (EGFR) and implications for EGFR-targeted drugs are discussed. Potential implications and opportunities for patient and drug selection for genotype-driven anticancer therapy are outlined.

Part 1: background, methodology, and clinical adoption of pharmacogenetics

Equivalent drug doses may lead to wide interpatient variability with regard to drug response, reflected by differences in drug activity and normal tissue toxicity. A major factor responsible for this variability is variation among patients in their genetic constitution. Genetic polymorphism may affect the activity of proteins encoded, which in turn may lead to changes in the pharmacokinetic and pharmacodynamic behavior of a drug, observed as differences in drug transport, drug metabolism, and pharmacodynamic drug effects. Recent insights into the functional effect of polymorphism in genes that are involved in the pharmacokinetics and pharmacodynamics of anticancer drugs have provided opportunities for patient-tailored therapy in oncology. Individualized pharmacotherapy based on genotype will help to increase treatment efficacy while reducing unnecessary toxicity, especially of drugs characterized by a narrow therapeutic window, such as anticancer drugs. We provide a series of four reviews aimed at implementing pharmacogenetic-based drug and dose prescription in the daily clinical setting for the practicing oncologist. This first part in the series describes the functional impact of genetic polymorphism and provides a general background to and insight into possible clinical consequences of pharmacogenetic variability. It also discusses different methodologies for clinical pharmacogenetic studies and provides a concise overview about the different laboratory technologies for genetic mutation analysis that are currently widely applied. Subsequently, pharmacogenetic association studies in anticancer drug transport, phase I and II drug metabolism, and pharmacodynamic drug effects are discussed in the rest of the series. Opportunities for patient-tailored pharmacotherapy are highlighted.

[Advances of drug resistance marker of gemcitabine for non-small cell lung cancer]

随着药物基因组学、药物遗传学的发展，基因指导下个体化治疗成为提高非小细胞肺癌（non-small cell lung cancer, NSCLC）化疗疗效的有效途径之一。确定药物的相关预测性分子标志物从而指导临床治疗、提高疗效被广泛关注。吉西他滨是目前NSCLC常用化疗药物之一，本文主要阐述了近年来吉西他滨药物耐药相关基因在NSCLC个体化治疗方面的研究进展。

Pharmacogenetic and germline prognostic markers of lung cancer

INTRODUCTION

Lung cancer is the leading global cause of cancer-related mortality. Interindividual variability in treatment response and cancer outcomes has focused attention on genetic polymorphisms as prognostic markers. We evaluated the overall contribution of candidate polymorphism association studies to our current understanding of the genetic predictors of lung cancer outcomes.

METHODS

We examined the results of 90 studies that evaluated associations between genetic polymorphisms and lung cancer outcomes published between January 1990 and May 2009.

RESULTS

A total of 170 genetic variations in 90 studies were identified. Overall survival was a primary outcome in 81% of the studies and toxicity in 19%. Candidate polymorphisms in the DNA repair/synthesis pathway were the most frequently studied. Strong evidence in large-scale confirmatory studies of any single polymorphism was lacking. Polymorphisms of EGFR, XRCC1, and ERCC1 were associated with pharmacogenetic outcomes, whereas polymorphisms of MDM2, p53, and GSTM1 were associated with prognostic outcomes. All remaining polymorphisms had results lacking or failing replication testing. Heterogeneity in study populations, incomplete reporting of important population or study characteristics, inadequate power, and inconsistencies in methodology were common.

CONCLUSIONS

Although the quality of existing studies involving the candidate polymorphism approach is highly variable, a small set of candidate polymorphisms was identified as potential biomarkers of clinical or pharmacogenetic outcome and would benefit from further replication testing. Newer approaches including haplotype tagging, pathway, genome-wide association, and combination methods with validative approaches may facilitate a more accurate prediction of lung cancer outcomes by genetic variation.

Role of the XRCC5/XRCC6 dimer in carcinogenesis and pharmacogenomics

Over the past few decades, the incidence of cancer has rapidly increased all over the world and cancer remains a major threat to public health. It is believed that cancer results from a series of genetic alterations that lead to the progressive disorder of the normal mechanisms controlling cell proliferation, differentiation, death and/or genomic stability. The response of the cell to genetic injury and its ability to maintain genomic stability by means of a variety of DNA repair mechanisms are therefore essential in preventing tumor initiation and progression. From the same viewpoint, the relative role of DNA repair as a biomarker for prognosis, predictor of drug and therapy responses or indeed as a target for novel gene therapy, is very promising. In this article, we have summarized the studies investigating the association between the XRCC5/XRCC6 dimer and the susceptibility to multiple cancers and discuss its role in carcinogenesis and its potential application to anticancer drug discovery.

Novel compounds in the treatment of lung cancer: current and developing therapeutic agents

Lung cancer is the leading cause of cancer-related death in the United States. Though incremental advances have been made in the treatment of this devastating disease during the past decade, new therapies are urgently needed. Traditional cytotoxic agents have been combined with other modalities with improved survival for early-stage patients. Newer cytotoxic agents targeting the same or different mechanisms have been developed at different stages. Optimization of various chemotherapy regimens in different settings is one of the aims of current clinical trials. Some predictive biomarkers (eg, excision repair cross-complementing 1, ERCC1) and histotypes (eg, adenocarcinoma) are found to be associated with resistance/response to some cytotoxic drugs. Another notable advance is the addition of targeted therapy to lung cancer treatment. Targeted agents such as erlotinib and bevacizumab have demonstrated clinical benefits and gained Food and Drug Administration approval for lung cancer. More agents targeting various signaling pathways critical to lung cancer are at different stages of development. Along with the effort of new targeted drug discovery, biomarkers such as epidermal growth factor receptor and anaplastic lymphoma kinase mutations have proven useful for patient selection, and more predictive biomarkers have been actively evaluated in non-small cell lung cancer. The paradigm of lung cancer treatment has shifted towards biomarker-based personalized medicine.

The ERCC1 N118N polymorphism does not change cellular ERCC1 protein expression or platinum sensitivity

Genetic polymorphisms in ERCC1 are thought to contribute to altered sensitivity to platinum-based chemotherapy. Although ERCC1 N118N (500 C>T, rs11615) is the most studied polymorphism, the impact of this polymorphism on platinum-based chemotherapy remains unclear. This is the first study in which the functional impact of ERCC1 N118N on gene expression and platinum sensitivity was explored. The aim of this study is to investigate if the reduced codon usage frequency of AAT, which contains the variant allele of the silent mutation, has functional impact on ERCC1 in a well-controlled biological system. Specifically, the ERCC1 cDNA clone with either the C or T allele was introduced into an ERCC1 deficient cell line, UV20, and assayed for the effect of the two alleles on ERCC1 transcription, translation and platinum sensitivity. Both ERCC1 mRNA and protein expression levels increased upon cisplatin treatment, peaking at 4h post-treatment, however there were no differences between the two alleles (p>0.05). Cells complemented with ERCC1 showed significantly higher survival proportion than the parental cell line following platinum exposure (p<0.0001), although no differences were observed between the cells transfected with the wild type or the polymorphic allele. These data suggest that N118N itself is not related to the phenotypic differences in ERCC1 expression or function, but rather this polymorphism may be linked to other causative variants or haplotypes.

No evidence of an association of ERCC1 and ERCC2 polymorphisms with clinical outcomes of platinum-based chemotherapies in non-small cell lung cancer: a meta-analysis

BACKGROUND

The nucleotide excision repair (NER) pathway modulates platinum-based chemotherapeutic efficacy by removing drug-induced DNA damage.

METHODS

To summarize published data on the association between NER genes and responses to platinum-based chemotherapies in non-small cell lung cancer (NSCLC), we performed a meta-analysis of 17 published studies of ERCC1 C118T/C8092A and ERCC2 Lys751Gln/Asp312Asn polymorphisms, including 2097 cancer patients. Primary outcomes included objective response (TR) (i.e., complete response+partial response vs. stable disease+progressive disease), progression-free survival (PFS) and overall survival (OS). We calculated odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) to estimate the risk or hazard.

RESULTS

We found that none of the ERCC1 C118T/C8092A and ERCC2 Lys751Gln/Asp312Asn polymorphisms alone was statistically significantly associated with objective response, PFS and OS in NSCLC patients.

CONCLUSION

There is no evidence to support the use of NER ERCC1 C118T/C8092A and ERCC2 Lys751Gln/Asp312Asn polymorphisms as prognostic predictors of platinum-based chemotherapies in NSCLC.

Pharmacogenetics in breast cancer: steps toward personalized medicine in breast cancer management

There is wide individual variability in the pharmacokinetics, pharmacodynamics, and tolerance to anticancer drugs within the same ethnic group and even greater variability among different ethnicities. Pharmacogenomics (PG) has the potential to provide personalized therapy based on individual genetic variability in an effort to maximize efficacy and reduce adverse effects. The benefits of PG include improved therapeutic index, improved dose regimen, and selection of optimal types of drug for an individual or set of individuals. Advanced or metastatic breast cancer is typically treated with single or multiple combinations of chemotherapy regimens including anthracyclines, taxanes, antimetabolites, alkylating agents, platinum drugs, vinca alkaloids, and others. In this review, the PG of breast cancer therapeutics, including tamoxifen, which is the most widely used therapeutic for the treatment of hormone-dependent breast cancer, is reviewed. The pharmacological activity of tamoxifen depends on its conversion by cytochrome P450 2D6 (CYP2D6) to its abundant active metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the coadministration of other drugs that inhibit CYP2D6 function, produce little endoxifen and hence derive limited therapeutic benefit from tamoxifen; the same can be said about the different classes of therapeutics in breast cancer. PG studies of breast cancer therapeutics should provide patients with breast cancer with optimal and personalized therapy.