Effect of ERCC1 Polymorphisms and the Modification by Smoking on the Survival of Non-Small Cell Lung Cancer Patients

Clinical Perspectives of ERCC1 in Bladder Cancer

ERCC1 is a key regulator of nucleotide excision repair (NER) pathway that repairs bulky DNA adducts, including intrastrand DNA adducts and interstrand crosslinks (ICLs). Overexpression of ERCC1 has been linked to increased DNA repair capacity and platinum resistance in solid tumors. Multiple single nucleotide polymorphisms (SNPs) have been detected in ERCC1 gene that may affect ERCC1 protein expression. Platinum-based treatment remains the cornerstone of urothelial cancer treatment. Given the expanding application of neoadjuvant and adjuvant chemotherapy in locally advanced bladder cancer, there is an emerging need for biomarkers that could distinguish potential responders to cisplatin treatment. Extensive research has been done regarding the prognostic and predictive role of ERCC1 gene expression and polymorphisms in bladder cancer. Moreover, novel compounds have been recently developed to target ERCC1 protein function in order to maximize sensitivity to cisplatin. We aim to review all the existing literature regarding the role of the ERCC1 gene in bladder cancer and address future perspectives for its clinical application.

Pharmacogenetics of platinum-based chemotherapy: impact of DNA repair and folate metabolism gene polymorphisms on prognosis of non-small cell lung cancer patients

Chemotherapy based on platinum compounds is the standard treatment for NSCLC patients with EGFR wild type, and is also used as second line in mutated EGFR patients. Nevertheless, this therapy presents poor clinical outcomes. ERCC1, ERCC2, XRCC1, MDM2, MTHFR, MTR, and SLC19A1 gene polymorphisms may contribute to individual variation in response and survival to platinum-based chemotherapy. The aim of this study was to investigate the influence of these polymorphisms on response and survival of NSCLC patients treated with platinum-based chemotherapy. A retrospective-prospective cohorts study was conducted, including 141 NSCLC patients. Polymorphisms were analyzed by PCR real-time with Taqman® probes. Patients with ERCC1 rs3212986-GG (p = 0.0268; OR = 2.50; CI_95% = 1.12-5.69) and XRCC1 rs25487-GG (p = 0.0161; OR = 2.99; CI_95% = 1.26-7.62) genotype showed significantly better ORR. Cox survival analysis revealed that patients carrying the MDM2 rs1690924-GG genotype (p = 0.0345; HR = 1.99; CI_95% = 1.05-3.80) presented higher risk of death. Furthermore, carriers of MTR rs1805087-A alleles (p = 0.0060; HR = 8.91; CI_95% = 1.87-42.42) and SLC19A1 rs1051266-AA genotype (p = 0.0130; HR = 1.74; CI_95% = 1.12-2.68) showed greater risk of progression. No influence of ERCC1 rs11615, ERCC2 rs13181, ERCC2 rs1799793, XRCC1 rs1799782, MDM2 rs1470383, MTHFR rs1801131, and MTHFR rs1801133 on platinum-based chemotherapy clinical outcomes was found. In conclusion, our results suggest that ERCC1 rs3212986, XRCC1 rs25487, MDM2 rs1690924, MTR rs1805087, and SLC19A1 rs1051266 gene polymorphisms may significantly act as predictive factors in NSCLC patients treated with platinum-based chemotherapy.

Pharmacogenetics of platinum-based chemotherapy in non-small cell lung cancer: predictive validity of polymorphisms of ERCC1

INTRODUCTION

The efficacy of platinum-based chemotherapy for patients with non-small cell lung cancer (NSCLC) is limited by chemoresistance. Platinum drugs damage DNA by introducing intrastrand and interstrand crosslinks which result in cell death. Excision repair cross-complementing 1 (ERCC1) is a member of the nucleotide excision repair (NER) pathway which erases such defects. Single nucleotide polymorphisms (SNPs) in ERCC1 impair this activity and have been suggested to predict the response to chemotherapy. Area covered: Among the polymorphisms of proteins involved in uptake, metabolism, cytotoxicity and efflux of platinum drugs, codon 118 C/T and C8092A in ERCC1 are the best characterized SNPs studied for their predictive power. Here, the divergent results for studies of these markers in NSCLC are summarized and the reasons for this contradictory data discussed. Expert opinion: Cytotoxicity of platinum compounds comprise complex cellular processes for which DNA repair may not constitute the rate limiting step. These drugs are administered as doublets to histologically diverse patients and, furthermore, the NER pathway in ERCC1 wildtype cohorts may be still impaired by the chemotherapeutics applied. At present, assessment of a limited number of polymorphism in DNA repair proteins is not reliably associated with response to treatment in NSCLC patients.

The Role of Deoxycytidine Kinase (dCK) in Radiation-Induced Cell Death

Deoxycytidine kinase (dCK) is a key enzyme in deoxyribonucleoside salvage and the anti-tumor activity for many nucleoside analogs. dCK is activated in response to ionizing radiation (IR)-induced DNA damage and it is phosphorylated on Serine 74 by the Ataxia-Telangiectasia Mutated (ATM) kinase in order to activate the cell cycle G2/M checkpoint. However, whether dCK plays a role in radiation-induced cell death is less clear. In this study, we genetically modified dCK expression by knocking down or expressing a WT (wild-type), S74A (abrogates phosphorylation) and S74E (mimics phosphorylation) of dCK. We found that dCK could decrease IR-induced total cell death and apoptosis. Moreover, dCK increased IR-induced autophagy and dCK-S74 is required for it. Western blotting showed that the ratio of phospho-Akt/Akt, phospho-mTOR/mTOR, phospho-P70S6K/P70S6K significantly decreased in dCK-WT and dCK-S74E cells than that in dCK-S74A cells following IR treatment. Reciprocal experiment by co-immunoprecipitation showed that mTOR can interact with wild-type dCK. IR increased polyploidy and decreased G2/M arrest in dCK knock-down cells as compared with control cells. Taken together, phosphorylated and activated dCK can inhibit IR-induced cell death including apoptosis and mitotic catastrophe, and promote IR-induced autophagy through PI3K/Akt/mTOR pathway.

A Significant Statistical Advancement on the Predictive Values of ERCC1 Polymorphisms for Clinical Outcomes of Platinum-Based Chemotherapy in Non-Small Cell Lung Cancer: An Updated Meta-Analysis

Background. There is no definitive conclusion so far on the predictive values of ERCC1 polymorphisms for clinical outcomes of platinum-based chemotherapy in non-small cell lung cancer (NSCLC). We updated this meta-analysis with an expectation to obtain some statistical advancement on this issue. Methods. Relevant studies were identified by searching MEDLINE, EMBASE databases from inception to April 2015. Primary outcomes included objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). All analyses were performed using the Review Manager version 5.3 and the Stata version 12.0. Results. A total of 33 studies including 5373 patients were identified. ERCC1 C118T and C8092A could predict both ORR and OS for platinum-based chemotherapy in Asian NSCLC patients (CT + TT versus CC, ORR: OR = 0.80, 95% CI = 0.67–0.94; OS: HR = 1.24, 95% CI = 1.01–1.53) (CA + AA versus CC, ORR: OR = 0.76, 95% CI = 0.60–0.96; OS: HR = 1.37, 95% CI = 1.06–1.75). Conclusions. Current evidence strongly indicated the prospect of ERCC1 C118T and C8092A as predictive biomarkers for platinum-based chemotherapy in Asian NSCLC patients. However, the results should be interpreted with caution and large prospective studies are still required to further investigate these findings.

ERCC1 SNPs as Potential Predictive Biomarkers in Non-Small Cell Lung Cancer Patients Treated With Platinum-Based Chemotherapy

Polymorphisms in ERCC1, XPD, and XRCC1 were examined for (a) association with the clinical outcome of 107 non-small cell lung cancer patients receiving front-line platinum-based chemotherapy, and (b) correlation with the ERCC1 mRNA levels of 176 chemo-naive primary tumors. The ERCC1-C8092 allele and the number of ERCC1 polymorphic variants (C8092A and Asn118Asn) were associated with progression-free survival. In non-squamous histology, tumoral ERCC1 mRNA levels were lower in patients homozygous for ERCC1-C8092 as compared with the patients carrying the A allele (p = .024). These findings merit investigation in larger cohorts of patients treated with uniform regimens.

Predicting chemosensitivity to gemcitabine and cisplatin based on gene polymorphisms and mRNA expression in non-small-cell lung cancer cells

Aim: We used a panel of 17 non-small-cell lung cancer cell lines to investigate whether the presence of polymorphisms in the RRM1, ERCC1, ABCB1 and MTHFR genes and alterations in their mRNA expression can affect the in vitro chemosensitivity to cisplatin and gemcitabine. Materials & methods: Polymorphisms in these genes were evaluated by direct sequencing. mRNA expression levels were assessed by realtime PCR. In vitro chemosensitivity to cisplatin and gemcitabine was expressed as IC50 values, using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Results: There was a significant, positive correlation between RRM1 mRNA expression and IC50 values for gemcitabine (r = 0.6533, p = 0.0045), and there was a significant, negative correlation between ABCB1 mRNA expression and IC50 values for cisplatin (r = -0.5459, p = 0.0287). When examining the association between the polymorphisms and IC50, we found that only the MTHFR 1298A>C polymorphism showed a tendency to be more chemosensitive to gemcitabine (p = 0.0440). Conclusion: These in vitro results suggest that mRNA expression levels of the RRM1 and ABCB1 genes may be useful indicators of chemosensitivity to gemcitabine and cisplatin, respectively. The MTHFR 1298A>C polymorphism was associated with gemcitabine chemosensitivity, which require further functional analysis with co-expressed genes and should be explored in prospective clinical studies to determine its potential clinical application as a predictive biomarker.

Original submitted 11 February 2014; Revision submitted 3 November 2014

ERCC1 Cys8092Ala and XRCC1 Arg399Gln polymorphisms predict progression-free survival after curative radiotherapy for nasopharyngeal carcinoma

Background

Single nucleotide polymorphisms (SNPs) in DNA repair genes can alter gene expression and activity and affect response to cancer treatment and, correspondingly, survival. The present study was designed to evaluate the utility of the XRCC1 Arg399Gln and ERCC1 Cys8092Ala SNPs, measured in pretreatment biopsy samples, as predictors of response to radiotherapy in patients with non-metastatic nasopharyngeal carcinoma (NPC).

Materials and methods

The study included 75 consecutive patients with stage II-IVA-B NPC. XRCC1 Arg399Glu and ERCC1 Cys8092Ala SNPs were identified from paraffin-embedded biopsy specimens via Sanger sequencing. Expression of p53 and pAkt protein was analyzed by immunohistochemical staining. Potential relationships between genetic polymorphisms and progression-free survival (PFS) were analyzed by using a Cox proportional hazards model, the Kaplan-Meier method, and the log-rank test.

Results

Multivariate analysis showed that carriers of the ERCC1 8092 Ala/Ala genotype [hazard ratio (HR) 1.882; 95% confidence interval (CI) 1.031–3.438; P = 0.039] and heavy smokers (≥20 pack-years) carrying the XRCC1 Arg/Arg genotype (HR 2.019; 95% CI 1.010–4.036; P = 0.047) had significantly lower PFS rates. Moreover, combined positive expression of p53 and pAkt led to significantly increased PFS in subgroups carrying the XRCC1 Gln allele (HR 7.057; 95% CI 2.073–24.021; P = 0.002) or the ERCC1 Cys allele (HR 2.568; 95% CI 1.056–6.248; P = 0.038).

Conclusions

The ERCC1 Cys8092Ala polymorphism is an independent predictor of response to radiotherapy for NPC, and the XRCC1 Arg399Glu mutation combined with smoking status seems to predict PFS as well. Our results further suggest a possible correlation between these genetic polymorphisms and p53 protein status on survival.

The association between the ERCC1/2 polymorphisms and the clinical outcomes of the platinum-based chemotherapy in non-small cell lung cancer (NSCLC): a systematic review and meta-analysis

The relationship between the ERCC1/2 single nucleotide polymorphisms (SNPs) and the clinical outcomes of the platinum-based chemotherapy in the non-small cell lung cancer (NSCLC) is still inconsistent and inconclusive despite extensive investigations have been conducted to address this question. In this meta-analysis, we aim to further explore the prognostic value of the ERCC1/2 SNPs in NSCLC by analyzing all currently available evidences. Relevant studies were searched in PubMed, Embase, and China National Knowledge Infrastructure. The inclusion criteria were platinum-based chemotherapy in NSCLC patients and evaluation of clinical outcomes in relation to the ERCC1 C118T, ERCC1 C8092A, ERCC2 Asp312Asn, and ERCC2 Lys751Gln. Clinical outcomes analyzed in this study included the overall response rate, overall survival (OS), and progression-free survival (PFS). Odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were calculated to examine the risk or hazard associated with each SNP. A total of 46 studies including 9,407 NSCLC patients were qualified for this meta-analysis. For ERCC1 C118T, the T allele was associated with a poor OS (HR = 1.35, 95% CI = 1.04-1.75); for ERCC2 Asp312Asn, the Asn variant was linked to an unfavorable OS (HR = 2.07, 95% CI = 1.11-3.88); and for ERCC2 Lys751Gln, patients with the Gln variant have a worse OS (HR = 1.22, 95% CI = 1.05-1.41) and PFS (HR = 1.35, 95% CI = 1.07-1.71). In addition, the main findings of the ERCC1/2 SNPs on chemotherapy toxicity were also summarized. This meta-analysis suggested that the ERCC1 C118T, ERCC2 Asp312Asn, and Lys751Gln may be useful biomarkers to predict the clinical outcomes of the platinum-based chemotherapy in NSCLC patients.

Polymorphisms in ERCC1 C8092A predict progression-free survival in metastatic/recurrent nasopharyngeal carcinoma treated with cisplatin-based chemotherapy

OBJECTIVES

We evaluated whether DNA repair gene polymorphisms had an effect on clinical outcomes in metastatic/recurrent nasopharyngeal carcinoma (NPC) patients treated with cisplatin-based chemotherapy.

MATERIALS AND METHODS

Clinical data of 101 patients with metastatic/recurrent NPC between 2004 and 2011 were reviewed. Five potentially functional polymorphisms (ERCC1 Asn118Asn, ERCC1 C8092A, XPD Lys751Gln, XRCC1 Arg399Gln and XRCC1 Arg280His) were genotyped using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

The ERCC1 C8092A polymorphism was an independent predictor of PFS in Chinese NPC patients treated with cisplatin-based chemotherapy. Compared to the patients carrying the C/C genotype, the patients with the C/A or A/A genotype had an increased risk of disease progression on cisplatin-based chemotherapy (7.9 vs. 9.3 months; HR 1.61; 95 % CI 1.08-2.61; p = 0.047). However, no association between the other polymorphisms, response rate, disease progression and survival was detected in metastatic/recurrent NPC patients.

CONCLUSION

The ERCC1 C8092A polymorphism might be a useful predictive marker in metastatic/recurrent NPC patients treated with cisplatin-based chemotherapy. However, a large-scale prospective study is warranted to validate our findings.

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.

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.

Association between polymorphisms of ERCC1 and survival in epithelial ovarian cancer patients with chemotherapy

Aim: We evaluated whether the ERCC1 polymorphisms had an effect on survival in epithelial ovarian cancer (EOC) patients with platinum-based chemotherapy. Materials & methods: Clinical data of 209 EOC patients between 2002 and 2008 were reviewed. The genotypes of 19007T/C and 8092C/A polymorphisms were assessed in all patients using PCR–RFLP. Results: The 19007T/C polymorphism was significantly associated with response to treatment. Compared with the patients carrying C/C genotype, the patients with the T/T genotype have a significantly decreased response to platinum-based chemotherapy (odds ratio: 32.26; 95% CI: 3.66–250.00). Cox’s multivariate analysis suggested that EOC patients with the T/T genotype had an increased risk of disease progression (hazard ratio: 3.34; 95% CI: 1.77–6.29) and death (hazard ratio: 2.87; 95% CI: 1.38–5.96) compared with those carrying the C/C genotype. Conclusion: The 19007T/C polymorphism may be a useful prognostic marker in patients with EOC treated with platinum-based chemotherapy in Chinese women.

Original submitted 26 October 2011; Revision submitted 5 December 2011

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.

Single nucleotide polymorphisms as susceptibility, prognostic, and therapeutic markers of nonsmall cell lung cancer

Lung cancer is a major public health problem throughout the world. Among the most frequent cancer types (prostate, breast, colorectal, stomach, lung), lung cancer is the leading cause of cancer-related deaths worldwide. Among the two major subtypes of small cell lung cancer and nonsmall cell lung cancer (NSCLC), 85% of tumors belong to the NSCLC histological types. Small cell lung cancer is associated with the shortest survival time. Although tobacco smoking has been recognized as the major risk factor for lung cancer, there is a great interindividual and interethnic difference in risk of developing lung cancer given exposure to similar environmental and lifestyle factors. This may indicate that in addition to chemical and environmental factors, genetic variations in the genome may contribute to risk modification. A common type of genetic variation in the genome, known as single nucleotide polymorphism, has been found to be associated with susceptibility to lung cancer. Interestingly, many of these polymorphisms are found in the genes that regulate major pathways of carcinogen metabolism (cytochrome P450 genes), detoxification (glutathione S-transferases), adduct removal (DNA repair genes), cell growth/apoptosis (TP53/MDM2), the immune system (cytokines/chemokines), and membrane receptors (nicotinic acetylcholine and dopaminergic receptors). Some of these polymorphisms have been shown to alter the level of mRNA, and protein structure and function. In addition to being susceptibility markers, several of these polymorphisms are emerging to be important for response to chemotherapy/radiotherapy and survival of patients. Therefore, it is hypothesized that single nucleotide polymorphisms will be valuable genetic markers in individual-based prognosis and therapy in future. Here we will review some of the most important single nucleotide polymorphisms in the metabolic pathways that may modulate susceptibility, prognosis, and therapy in NSCLC.

Lack of correlation between ERCC1 (C8092A) single nucleotide polymorphism and efficacy/toxicity of platinum based chemotherapy in Chinese patients with advanced non-small cell lung cancer

PURPOSE

We investigated whether single nucleotide polymorphism of excision repair cross-complementation group 1 C8092A affected the clinical outcomes and toxicity in advanced stage non-small cell lung cancer patients receiving first line platinum based chemotherapy.

MATERIAL/METHODS

A total of 300 chemotherapy treated patients were examined for C8092A genotypes in peripheral blood samples.

RESULTS

Overall response rate was 33.6% and median overall survival was 13.5 months. There was no significant correlation between C8092A single nucleotide polymorphism and overall survival, tumor response or toxicity for platinum-based chemotherapy.

CONCLUSIONS

Excision repair cross-complementing group 1 (ERCC1) showed controversial results in different studies that have been carried out until now. In our Chinese population there is no correlation between ERCC1 C8092A SNP and efficacy or toxicity. Ethnicity could be a possible explanation for these controversial results.

An Evidence-Based Approach to the Use of Predictive Biomarkers in the Treatment of Non- Small Cell Lung Cancer (NSCLC)

Recent advances in the treatment of non-small cell lung cancer (NSCLC) have led to improvements in patient survival and quality of life. It is unclear whether molecular abnormalities associated with NSCLC cell survival, growth and proliferation are useful in predicting treatment benefit. We conducted a systematic review to establish which biomarkers contribute meaningfully to the management of NSCLC. A team of researchers searched PubMed and conference proceedings (ASCO, ESMO, IASLC, USCAP) using MESH terms for NSCLC and randomized trials (RCT), plus keywords for variables of interest. Evidence from multiple RCTs confirmed that histologic subtype is prognostic for survival and predictive of treatment efficacy and/or toxicity in NSCLC. Likewise, activating mutations of the epidermal growth factor receptor (EGFR) are associated with benefit from EGFR tyrosine kinase inhibitors in patients with advanced non-squamous NSCLC and should be assessed routinely. No biomarkers to date reliably predict response to anti-Vascular Endothelial Growth Factor (VEGF) therapies. There are inconsistent data on the role of ERCC1, BRCA, Beta tubulin III, RRM1, K-RAS, or TP-53 in treatment decisions. These tests should not be routinely used in selecting treatment at this time, whereas EML4/ALK translocations predict responses to specific targeted agents, the optimal assessment of this molecular abnormality has yet to be established. Personalized care of patients with NSCLC based on biomarkers is increasingly important to both clinical practice and research.

Systematic evaluation of genetic variants in three biological pathways on patient survival in low-stage non-small cell lung cancer

INTRODUCTION

Studies from selected candidate genes suggest that single-nucleotide polymorphisms (SNPs) involved in glutathione metabolism, DNA repair, or inflammatory responses may affect overall survival (OS) in stages I to II or low-stage non-small cell lung cancer (LS-NSCLC); however, results are inconclusive. In this study, we took a systematic pathway-based approach to simultaneously evaluate the impact of genetic variation from these three pathways on OS after LS-NSCLC diagnosis.

METHODS

DNA from 647 patients with LS-NSCLC was genotyped for 480 SNPs (tag-SNPs) tagging 57 genes from the three candidate pathways. Associations of tag-SNPs with OS were assessed at the individual SNP and whole gene levels, adjusting for age, tumor stage, surgery type, and adjuvant therapy. The genotype combinations of the SNPs associated with OS were also estimated.

RESULTS

Among the 412 tag-SNPs that were successfully genotyped and passed quality assessments, 28 showed association with OS (p < 0.05). Two of the 28 were estimated to have less than a 20% chance of being false positives (rs3768490 in GSTM5: p = 1.32 × 10, q = 0.06; rs1729786 in ABCC4: p = 9.25 × 10, q = 0.20). Gene-based analysis suggested that in addition to GSTM5 and ABCC4, variation in two other genes, PTGS2 and GSTA2, was also associated with OS.

CONCLUSIONS

We describe further evidence that variations in genes involved in the glutathione and inflammatory response pathways are associated with OS in patients with LS-NSCLC. Further studies are warranted to verify our findings and elucidate their functional mechanisms and clinical utility leading to improved survival for patients with lung cancer.

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.

DNA repair gene polymorphism associated with sensitivity of lung cancer to therapy

This study aimed to investigate association between single-nucleotide polymorphisms (SNPs) of excision repair cross-complementing gene 1 (ERCC1), excision repair cross-complementing gene 2 (ERCC2), and X-ray repair cross-complementing group 1 (XRCC1) with sensitivity of advanced non-small cell lung cancer (NSCLC) patients to platinum-based chemotherapy. A total of 89 NSCLC patients were recruited and treated with two cycles of platinum-based chemotherapy. DNA was extracted from peripheral lymphocytes for detection of SNPs of ERCC1 Asn118Asn, ERCC2 Lys751Gln, and XRCC1 Arg399Gln. The overall response rate of these patients was 29.2%. There was no statistically significant difference of treatment response between the wild genotypes and the variant genotypes for the ERCC1 Asn118Asn and ERCC2 Lys751Gln gene. The distributions of genotypes XRCC1 Arg399Gln differed significantly between the response and non-response groups (76.9 vs. 23.1%, P = 0.001). The XRCC1 399Arg/Arg genotype carriers had a higher response rate than that of the Gln genotype carriers (OR = 4.81, 95%CI = 1.778-13.013, P = 0.002). The combination of the favorable genotypes of ERCC1, ERCC2, and XRCC1 had a higher response rate compared to that of patients with other genotypes. The combined polymorphisms of ERCC1, ERCC2, and XRCC1 may be associated with sensitivity of NSCLC to platinum-based chemotherapy. Further studies will verify these SNPs as biomarkers for prediction of platinum-based chemotherapy responses of NSCLC patients.

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.

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.

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.

Tumor and host factors that may limit efficacy of chemotherapy in non-small cell and small cell lung cancer

While chemotherapy provides useful palliation, advanced lung cancer remains incurable since those tumors that are initially sensitive to therapy rapidly develop acquired resistance. Resistance may arise from impaired drug delivery, extracellular factors, decreased drug uptake into tumor cells, increased drug efflux, drug inactivation by detoxifying factors, decreased drug activation or binding to target, altered target, increased damage repair, tolerance of damage, decreased proapoptotic factors, increased antiapoptotic factors, or altered cell cycling or transcription factors. Factors for which there is now substantial clinical evidence of a link to small cell lung cancer (SCLC) resistance to chemotherapy include MRP (for platinum-based combination chemotherapy) and MDR1/P-gp (for non-platinum agents). SPECT MIBI and Tc-TF scanning appears to predict chemotherapy benefit in SCLC. In non-small cell lung cancer (NSCLC), the strongest clinical evidence is for taxane resistance with elevated expression or mutation of class III beta-tubulin (and possibly alpha tubulin), platinum resistance and expression of ERCC1 or BCRP, gemcitabine resistance and RRM1 expression, and resistance to several agents and COX-2 expression (although COX-2 inhibitors have had minimal impact on drug efficacy clinically). Tumors expressing high BRCA1 may have increased resistance to platinums but increased sensitivity to taxanes. Limited early clinical data suggest that chemotherapy resistance in NSCLC may also be increased with decreased expression of cyclin B1 or of Eg5, or with increased expression of ICAM, matrilysin, osteopontin, DDH, survivin, PCDGF, caveolin-1, p21WAF1/CIP1, or 14-3-3sigma, and that IGF-1R inhibitors may increase efficacy of chemotherapy, particularly in squamous cell carcinomas. Equivocal data (with some positive studies but other negative studies) suggest that NSCLC tumors with some EGFR mutations may have increased sensitivity to chemotherapy, while K-ras mutations and expression of GST-pi, RB or p27kip1 may possibly confer resistance. While limited clinical data suggest that p53 mutations are associated with resistance to platinum-based therapies in NSCLC, data on p53 IHC positivity are equivocal. To date, resistance-modulating strategies have generally not proven clinically useful in lung cancer, although small randomized trials suggest a modest benefit of verapamil and related agents in NSCLC.

Downregulation of XPF-ERCC1 enhances cisplatin efficacy in cancer cells

Bulky cisplatin lesions are repaired primarily by nucleotide excision repair (NER), in which the structure specific endonuclease XPF-ERCC1 is a critical component. It is now known that the XPF-ERCC1 complex has repair functions beyond NER and plays a role in homologous recombination (HR). It has been suggested that expression of ERCC1 correlates with cisplatin drug resistance in non-small cell lung cancer (NSCLC). In our study, using NSCLC, ovarian, and breast cancer cells, we show that the XPF-ERCC1 complex is a valid target to increase cisplatin cytotoxicity and efficacy. We targeted XPF-ERCC1 complex by RNA interference and assessed the repair capacity of cisplatin intrastrand and interstrand crosslinks by ELISA and alkaline comet assay, respectively. We also assessed the repair of cisplatin-ICL-induced double-strand breaks (DSBs) by monitoring gamma-H2AX focus formation. Interestingly, XPF protein levels were significantly reduced following ERCC1 downregulation, but the converse was not observed. The transcript levels were unaffected suggesting that XPF protein stability is likely affected. The repair of both types of cisplatin-DNA lesions was decreased with downregulation of XPF, ERCC1 or both XPF-ERCC1. The ICL-induced DSBs persist in the absence of XPF-ERCC1. The suppression of the XPF-ERCC1 complex significantly decreases the cellular viability which correlates well with the decrease in DNA repair capacity. A double knockdown of XPF-ERCC1 displays the greatest level of cellular cytotoxicity when compared with XPF or ERCC1 alone. The difference in cytotoxicity observed is likely due to the level of total protein complex remaining. These data demonstrate that XPF-ERCC1 is a valid target to enhance cisplatin efficacy in cancer cells by affecting cisplatin-DNA repair pathways.

The platinum-based treatments for advanced non-small cell lung cancer, is low/negative ERCC1 expression better than high/positive ERCC1 expression? A meta-analysis

BACKGROUND

The predictive value of ERCC1 for prognosis and sensitivity to platinum-based chemotherapy in patients with non-small cell lung cancer (NSCLC) remains controversial. This meta-analysis was performed to provide an assessment of whether expression variations of ERCC1 are associated with objective response and median survival in patients with advanced NSCLC treated with platinum-based chemotherapy.

METHODS

We searched MEDLINE, EMBASE and CNKI for all eligible studies and conducted a meta-analysis of 12 studies (n=836 patients) that evaluated the correlation between ERCC1 levels (detected by immunohistochemistry or real-time reverse transcriptase PCR) and objective response or median survival in patients receiving platinum-based chemotherapy for advanced NSCLC. Pooled odds ratios (OR) for the objective response were calculated using the Mantel-Haenszel method. Pooled median ratios for median survival were calculated using the weighted sum of the log-ratio of median ratios from each individual study.

RESULTS

Among 836 tumors, ERCC1 expression was high/positive in 416 (49.8%) and low/negative in 420 (50.2%). Response to platinum-based chemotherapy was significantly higher in patients with ERCC1 low/negative expression (OR=0.48; 95% CI, 0.35-0.64; P<0.00001). Median survival time was significantly prolonged when ERCC1 low/negative expression was compared with ERCC1 high/positive expression (MR: 0.77; 95% CI, 0.47-1.07; P<0.00001).

CONCLUSIONS

Low/negative expression of ERCC1 was associated with higher objective response and median survival in advanced NSCLC patients treated with platinum-based chemotherapy. ERCC1 may be a suitable marker of prognosis and sensitivity to platinum-based chemotherapy in patients with advanced NSCLC.

Pharmacogenomics of platinum-based chemotherapy in NSCLC

NSCLC is the leading cause of cancer-related death in the US. Patients with NSCLC are mostly treated with platinum-based chemotherapy, often in combination with radiation therapy. However, the development of chemo-resistance is a major hurdle limiting treatment success. In this review, we summarize the current understanding of the genetic factors modulating chemoresistance to platinum chemotherapeutics and their association with clinical outcomes for NSCLC patients. We focus on candidate pathways responsible for drug influx and efflux, metabolism and detoxification, DNA damage repair, and other downstream cellular processes that modulate the effect of platinum-based therapy. We also discuss the application of pathway-based polygenic and genome-wide approaches in identifying genetic factors involved in NSCLC clinical outcomes. Overall, current studies have shown that the effects of each individual polymorphism on clinical outcomes are modest suggesting that a more comprehensive approach that incorporates polygenetic, phenotypic, epidemiologic and clinical variables will be necessary to predict prognosis for NSCLC patients receiving platinum-based chemotherapeutics.

Effect of BRCA1 Haplotype on Survival of Non–Small-Cell Lung Cancer Patients Treated With Platinum-Based Chemotherapy

Purpose

To determine whether germ-line variations in BRCA1 affect outcome in non–small-cell lung cancer (NSCLC) patients treated with platinum combination chemotherapy.

Patients and Methods

We evaluated the associations of four tagging BRCA1 polymorphisms and their haplotypes with treatment outcome in 300 NSCLC patients at stages IIIA (16%), IIIB (31%), and IV (53%).

Results

The median age was 63 years (range, 28 to 89 years). Histologically, 139 (46.3%) of the patients had squamous cell carcinomas and 137 (45.7%) had adenocarcinomas. Patient median survival time (MST) was 13.0 months. We observed no significant association between any of the tagging polymorphisms [S1613G, IVS13-1893 (A>C), IVS12-1207 (C>T), and IVS12+112 (C>A)] and overall survival. Of the five haplotypes evaluated (AACC, AACA, GCTC, GATC, and AATC), the survival of patients with two copies of the AACC (wild-type) haplotype was significantly shorter than that of patients with zero to one copies (MST, 8.47 v 14.57 months; log-rank P = .0066), even after adjustment for body weight loss, performance status, stage, second-line treatment, and radiation therapy (hazard ratio = 2.097; 95% CI, 1.339 to 3.284). The survival of patients with squamous cell carcinoma and two copies was significantly shorter than that of other patients with squamous cell carcinoma (MST, 6.8 v 15.3 months; log-rank P = 3.6 × 10−5), whereas differences in survival between the two adenocarcinoma groups was not significant (log-rank P = .677).

Conclusion

These findings suggest that the AACC haplotype of the BRCA1 gene is an important prognostic marker in NSCLC patients treated with platinum combination chemotherapy.

Genetic polymorphisms and head and neck cancer outcomes: a review

Head and neck cancer (HNC) patients have variable prognoses even within the same clinical stage and while receiving similar treatments. The number of studies of genetic polymorphisms as prognostic factors of HNC outcomes is growing. Candidate polymorphisms have been evaluated in DNA repair, cell cycle, xenobiotic metabolism, and growth factor pathways. Polymorphisms of XRCC1, FGFR, and CCND1 have been consistently associated with HNC survival in at least two studies, whereas most of the other polymorphisms have either conflicting data or were from single studies. Heterogeneity and lack of description of patient populations and lack of accounting for multiple comparisons were common problems in a significant proportion of studies. Despite a large number of exploratory studies, large replication studies in well-characterized HNC populations are warranted.

Polymorphisms in MGMT and DNA repair genes and the risk of esophageal adenocarcinoma

Rates of adenocarcinoma of the esophagus (EAC) and esophago-gastric junction (EGJAC) have increased rapidly in recent decades. The primary risk factors, gastro-esophageal acid reflux and smoking, are potentially genotoxic through the generation of N-nitroso compounds. The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) is the major cellular defense against alkylating DNA damage. We compared patients with EAC (n = 263) or EGJAC (n = 303) with matched population controls (n = 1,337) for the frequency of 5 MGMT single nucleotide polymorphisms (SNPs) (rs12269324, rs12268840, L84F, I143V, K178R), as well as SNPs in DNA repair genes ERCC1 (N118N), XRCC1 (Q399R) and XPD (K751Q). Relative risks were estimated using multivariable logistic regression. Potential biological interaction was assessed through the synergy index S. Each MGMT SNP conferred increased risks of EAC but not EGJAC; strongest associations were found for the 2 variant MGMT alleles rs12268840 and I143V (p = 0.005 and p < 0.001, respectively). Homozygous carriers of MGMT rs12268840 with frequent acid reflux had significantly higher risks of EAC (OR 15.5, 95% CI 5.8-42) than expected under an additive model, consistent with biological interaction (S = 3.3, 95% CI 1.1-10). Modest, nonsignificant interactions with smoking were also observed. Homozygous variant ERCC1 genotype was associated with reduced risks of EAC (OR 0.6, 95% CI 0.4-1.1), while the homozygous variant XRCC1 genotype conferred higher risks of EGJAC (OR 1.6, 95% CI 1.1-2.4). No associations with EAC or EGJAC were observed with XPD (rs13181). In summary, MGMT SNPs are associated with increased risks of EAC. Exposure to acid reflux, and possibly smoking, confer markedly higher risks among homozygous variant genotype carriers.

Molecular pathology--translating research into clinical practice: an expanding frontier in surgical oncology

Molecular assays have now become essential to the pathologist and clinician alike in diagnosing and managing disease. This article highlights the techniques and molecular targets no longer ancillary to basic research. Ripe for discussion are the likely future impact of genetics on clinical care, the potential models for service provision, and the broader ethical, legal, and social issues related to the use of genetic information for nonmedical purposes. Molecular methods are forecasted to increase in assisting in the diagnosis of human diseases. The author's mission is to embrace this discipline and use these technologies in clinical practice.