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

Current status of excision repair cross complementing-group 1 (ERCC1) in cancer

Cisplatin, carboplatin and oxaliplatin are some of the most widely used anti-cancer agents in solid tumours. The cytotoxicity of platinating agents is directly related to their ability to cause DNA intra-strand crosslinks that trigger a series of intracellular events that ultimately result in cell death. DNA intra-strand crosslinks are processed and repaired by the nucleotide excision repair pathway. It is now clear that nucleotide excision repair (NER) capacity may have a major impact on the emergence of resistance, normal tissue tolerance and patient outcomes. ERCC1 is a key player in NER. In this review, we provide an overview of mammalian NER and then focus on biochemical, structural and pre-clinical aspects of ERCC1. We then present current clinical evidence implicating ERCC1 as a predictive and prognostic marker in cancer. Early evidence also suggests that ERCC1 or the pathways involved in the regulation of ERCC1 expression may be attractive anti-cancer targets. Such agents are expected to potentiate the cytotoxicity of platinating agents and could have a major impact on cancer therapy.

Mechanisms of resistance to cisplatin and carboplatin

While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.

Polymorphism of XRCC1 predicts overall survival of gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population

Pharmacogenetic advances in cancer chemotherapy have the potential to predict clinical benefit to particular regimens. Platinum agents have shown to be effective in the treatment of gastric cancer. We assessed whether single nucleotide polymorphisms (SNPs) in xeroderma pigmentosum group D (XPD), X-ray repair cross complementing group 1 (XRCC1) and glutathione S-transferase P1 (GSTP1) predicted overall survival in gastric cancer patients receiving oxaliplatin-based chemotherapy in Chinese population. SNPs of XPD-751, XRCC1-399 and GSTP1-105 in 62 gastric cancer patients were evaluated using the TaqMan 5' nuclease assay. Genotypes were correlated to survival. The median overall survival time was 322 days (range: 56-2058 days). The median survival times for patients with Arg/Arg or Arg/Gln genotypes of XRCC1 gene were significantly longer than others (P=0.03). For 58 patients with ECOG PS (Eastern Cooperative Oncology Group performance status)<or=2, more obvious significance was demonstrated (P=0.002). Patients with XRCC1-399 Gln/Gln genotype demonstrated a significant worse survival. No significant association was found between SNPs of XPD-751, GSTP1-105 and survival (P=0.125, 0.475, respectively). XRCC1 genotyping might make tailor chemotherapy possible for gastric cancer patients treated with oxaliplatin-based chemotherapy.

Insights into the role of heritable genetic variation in the pharmacokinetics and pharmacodynamics of anticancer drugs

Pharmacogenetics in oncology will ideally allow oncologists to individualise therapy based on a genetic test result. Severe toxicity and clinically significant underdosing may be avoided, whereas predicted non-responders can be offered alternative therapy. This manuscript gives an overview of heritable variants in the genes of nine enzymes or pathways that have been studied most extensively in anticancer chemotherapy. Even though many pharmacogenetic association studies have been published, there is a need for more research. In particular, there is a need for replication of data and development of predictive models. Prospective trials are required to establish clinical value and cost-effectiveness of pharmacogenetic testing in oncology.

Prospective Assessment of XPD Lys751Gln and XRCC1 Arg399Gln Single Nucleotide Polymorphisms in Lung Cancer

PURPOSE

XRCC1 and XPD play key roles in the repair of DNA lesions and adducts. Contrasting findings have been reported on the effect of polymorphisms of these genes on the response to platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC). This study aimed to investigate the relationship between the XPD Lys751Gln and XRCC1 Arg399Gln genotypes and outcome in lung cancer patients.

EXPERIMENTAL DESIGN

We genotyped 203 NSCLC and 45 small-cell lung carcinoma (SCLC) patients for the two polymorphisms. Most of the patients (81%) received a platinum-based chemotherapy.

RESULTS

The patients' genotype frequencies did not significantly differ from controls and both groups were in Hardy-Weinberg equilibrium for the two polymorphisms. The XRCC1399 Gln/Gln variant genotype was associated with a higher median survival time (80 weeks versus 54.6 weeks for the Arg/Gln heterozygous and 55.6 weeks for the wild-type Arg/Arg genotype; P=0.09). At the multivariable analysis adjusted for histology, stage of the disease, performance status, age, and gender, the Gln/Gln genotype was associated with a better survival of borderline significance in the subgroup of patients treated with cisplatin (hazard ratio, 0.55; 95% CI, 0.30-1.00); this association became significant for those with grade 3-4 clinical toxicity (hazard ratio, 0.46; 95% CI, 0.22-0.98). No association between XPD Lys751Gln genotype and clinical outcome was found.

CONCLUSION

This prospective investigation provides suggestive evidence of a favorable effect of the XRCC1399 Gln/Gln genotype on survival in platinum-treated NSCLC and, for the first time, in SCLC patients also. This contrasts with other authors who did not include non-platinum-treated patients, but it does fit the expectation for a suboptimal ability to remove DNA adducts.

The Role of Pharmacogenetics in Adjuvant Treatment of Non-small Cell Lung Cancer

The disappointing results of long-term survival among patients with non-small cell lung cancer (NSCLC) may reflect the lack of knowledge of the ways in which molecular abnormalities of neoplastic cells affect responsiveness to anticancer therapy. Remarkable advances in the understanding of NSCLC cancer biology have been made over the past decade, including the discovery of critical mutations in oncogenes (i.e., mutation of K-Ras and c-myc gene), as well as the loss of tumor-suppressor genes, such as TP53, 16INK4, or Rb. The future challenge of NSCLC chemotherapy relies on the identification of molecular markers that are predictive of drug sensitivity and help in the selection of chemotherapeutic agents best suited to the individual patient. Other intriguing issues will be the identification of the optimal drug sequence in combination regimens, as well as polymorphisms of genes involved in severe toxicities.

A pharmacogenomic study of docetaxel and gemcitabine for the initial treatment of advanced non-small cell lung cancer

BACKGROUND

Pharmacogenomic profiling is an attractive strategy for individualizing chemotherapy. Several genetic polymorphisms predict the survival of patients with non-small cell lung cancer treated with platinum-based chemotherapy. This phase II clinical trial was performed using a non-platinum-based chemotherapy doublet. The impact of previously identified polymorphisms on clinical outcomes was assessed.

METHODS

Patients with advanced non-small cell lung cancer who had not received previous chemotherapy were treated with docetaxel 40 mg/m2 on days 1 and 8 and gemcitabine 800 mg/m2 days 1 and 8 every 21 days until disease progression or unacceptable toxicity. A pretreatment blood sample was obtained, and genomic DNA was analyzed for polymorphisms in DNA repair and metabolic genes.

RESULTS

Forty-nine patients were enrolled and evaluated for response and survival. The overall radiographic response rate was 38%, and the median survival was 8.6 months. Nonhematologic toxicity was generally mild. Two treatment related deaths occurred: one due to neutropenic sepsis during the first cycle and one due to pulmonary edema after 12 cycles of treatment. Polymorphisms in XPD, XRCC1, and XRCC3 did not significantly predict survival, but trends similar to those reported for platinum-based chemotherapy were observed. The wild-type XPD genotype was associated with prolonged survival and a significantly higher risk of grade 4 neutropenia (p = 0.02).

CONCLUSION

This regimen of docetaxel and gemcitabine is well tolerated and active for the treatment of advanced non-small cell lung cancer. The impact of XPD polymorphisms on hematologic toxicity is similar to what has been reported for platinum-based chemotherapy.

Polymorphisms in DNA repair genes and therapeutic outcomes of AML patients from SWOG clinical trials

Repair of damage to DNA resulting from chemotherapy may influence drug toxicity and survival in response to treatment. We evaluated the role of polymorphisms in DNA repair genes APE1, XRCC1, ERCC1, XPD, and XRCC3 in predicting therapeutic outcomes of older adults with acute myeloid leukemia (AML) from 2 Southwest Oncology Group (SWOG) clinical trials. All patients received standard chemotherapy induction regimens. Using logistic and proportional hazards regression models, relationships between genotypes, haplotypes, and toxicities, response to induction therapy, and overall survival were evaluated. Patients with XPD Gln751C/Asp312G (‘D’) haplotype were more likely to have complete response (OR = 3.06; 95% CI, 1.44-6.70) and less likely to have resistant disease (OR = 0.32; 95%CI, 0.14-0.72) than patients with other haplotypes. ERCC1 polymorphisms were significantly associated with lung (P = .037) and metabolic (P = .041) toxicities, and patients with the XRCC3 241Met variant had reduced risk of liver toxicity (OR = 0.32; 95%CI, 0.11-0.95). Significant associations with other toxicities were also found for variant XPD genotypes/haplotypes. These data from clinical trials of older patients treated for AML indicate that variants in DNA repair pathways may have an impact on both outcomes of patients and toxicities associated with treatments. With validation of results in larger samples, these findings could lead to optimizing individual chemotherapy options.

Genetic polymorphisms and treatment response in advanced non-small cell lung cancer

BACKGROUND

Genetic polymorphisms involved in DNA repair and apoptosis are suspected to influence patient response to cancer treatment. To evaluate the effect of genetic variations on chemotherapy and/or radiotherapy, we genotyped four single nucleotide polymorphisms (SNPs) in ATM (A60G), ERCC1 (Asn118Asn), APE1 (Asn148Glu), and iASPP (A67T), and examined their associations with treatment response among patients with advanced non-small cell lung cancer (NSCLC).

METHODS

Included in the study were 230 patients diagnosed with inoperable advanced NSCLC. Of these patients, 76 received platinum-based chemotherapy, 125 received chemotherapy plus radiation, and 29 received radiotherapy only. The SNPs were genotyped using the TaqMan methods.

RESULTS

Among the patients who received chemotherapy only, ERCC1 (Asn118Asn) genotype was significantly associated with treatment response. Patients with either one or two T alleles (T/T+C/T) at Asn118Asn were more likely not to respond to platinum-based chemotherapy compared to those without the T allele (OR=4.10, 95% CI: 1.31-12.85). For patients who were treated with both chemotherapy and radiotherapy, treatment response seemed to differ substantially between patients with different genotypes of iASPP (A67T). Patients carrying an A allele (A/T+A/A) at A67T were more likely to respond to combined chemotherapy and radiotherapy compared to those not carrying the A allele (OR=0.25, 95% CI: 0.08-0.74). An association with treatment response was also suggested for the selected polymorphism in APE1, but no association was found for the ATM polymorphism.

CONCLUSION

We found that SNPs in ERCC1 and iASPP were associated with response to chemotherapy or combined chemotherapy and radiotherapy in NSCLC patients. These findings support the notion that genetic variations related to DNA repair or apoptosis may affect the effect of chemotherapy or radiation on NSCLC.

Pharmacogenetics of cancer chemotherapy

Significant heterogeneity in the efficacy and toxicity of chemotherapeutic agents is observed within cancer populations. Pharmacogenetics (PGx) is the study of inheritance in interindividual variation in drug disposition. The allure of pharmacogenetics, in the treatment of cancer patients, comes from the potential for individualisation of cancer therapy, minimizing toxicity, while maximizing efficacy. In this review we will focus on the current and potential clinical applications of pharmacogenetics in cancer therapy by citing relevant examples and discussing the possible approaches which may be used to establish a reliable, reproducible and cost-effective test for clinically relevant genetic polymorphisms, using easily accessible biological samples (e.g., blood and tumour samples). Ideally, routine management of patients would include analysis of their single nucleotide polymorphism linkage disequilibrium (SNP-LD) profile prior to treatment, allowing stratification of patients into treatment groups, thus individualising their therapy. In order to achieve this ambition, a combination of different approaches (candidate gene, genome-wide and pathway driven) will be required from scientists and clinician scientists, as well as an increased understanding and incorporation of pharmacogenetic aims and endpoints into current and future clinical trials.

DNA-Repair Gene Polymorphisms Predict Favorable Clinical Outcome Among Patients With Advanced Squamous Cell Carcinoma of the Head and Neck Treated With Cisplatin-Based Induction Chemotherapy

Purpose

Cisplatin kills tumor cells through DNA cross linking. Alterations in the function of DNA repair genes may affect DNA repair proficiency and influence cancer patients' response to cisplatin. We studied whether single nucleotide polymorphisms (SNPs) of DNA repair genes predict the response to cisplatin or prognosis in patients with squamous cell carcinoma of the head and neck (SCCHN).

Methods

A polymerase chain reaction–restriction fragment length polymorphism (RFLP) approach was used to determine the frequency of the SNPs: XPD-Asp312Asn, XPD-Lys751Gln, ERCC1-C8092A, and XRCC1-Arg399Gln in DNA from peripheral lymphocytes of 103 stage IV SCCHN patients.

Results

The frequencies of the distinct genotypes were, respectively, for the homozygous common allele, heterozygous and homozygous polymorphic variant: 53%, 40%, and 7% for ERCC1; 50%, 42%, and 8% for XPD-312; 35%, 57%, and 8% for XPD751; and 35%, 51%, and 13% for XRCC1. Patients with only common alleles at all the SNPs tested had a median overall survival of 5.1 months (range, 4.3 to 6.0 months) as compared with not reached for patients with at least one polymorphic variant (P < .001). Estimates from Cox's multivariate analysis suggest that the accumulation of each polymorphic variant decreases the probability of dying by a factor of 2.1 (P < .001; the presence of seven polymorphic variants confers a 175-fold protection). The accumulation of polymorphic variants increases by 2.94-fold the probability of achieving a complete response to treatment (P = .041).

Conclusion

Using a multivariate model, the presence of polymorphic variants in DNA-repair genes are powerful prognosis factors and response to cisplatin predictors among SCCHN patients.

Single nucleotide polymorphisms in DNA repair genes might be prognostic factors in muscle-invasive bladder cancer patients treated with chemoradiotherapy

DNA repair enzymes repair DNA damaged by platinum agents and ionising radiation. Single nucleotide polymorphisms (SNPs) in DNA repair genes modulate the repair capacity and might affect response and prognosis following platinum-based chemoradiotherapy (CRT). We investigated associations between the functional SNPs in DNA repair genes and response and survival in muscle-invasive bladder cancer patients treated with CRT to determine the predictive value of the SNPs in patient selection for bladder conservation therapy. The study group comprised 78 patients who underwent CRT for transitional cell carcinoma of the bladder. Single nucleotide polymorphisms in xeroderma pigmentosum complementation groups C (Lys939Gln, A/C), D (XPD; Lys751Gln, A/C), and G (Asp1104His, G/C), and X-ray repair cross-complementing groups 1 (XRCC1; Arg399Gln, G/A) and 3 (Thr241Met, T/C) genes were genotyped. Combined genotypes with at least one variant allele in XPD or XRCC1 were significantly associated with improved cancer-specific survival compared with remaining groups (P=0.009). In multivariate analysis, only the combined XPD and XRCC1 genotypes were independently associated with cancer-specific survival (P=0.04). The association was stronger in stage T3/T4 patients (P=0.0008). These results suggest that combined XPD and XRCC1 genotypes might be prognostic factors in muscle-invasive bladder cancer patients treated with CRT.

XRCC1 R399Q polymorphism is associated with response to platinum-based neoadjuvant chemotherapy in bulky cervical cancer

OBJECTIVES

The aim of the study was to assess whether the genetic polymorphisms were associated with the tumor response in patients treated with platinum-based neoadjuvant chemotherapy (NAC) for bulky cervical cancer.

METHODS

We retrospectively reviewed the clinical data and recruited paraffin-embedded, formalin-fixed tissues of 36 patients with bulky cervical carcinoma. All patients underwent two or three cycles of platinum-based NAC followed by radical hysterectomy. We determined the genotypes of each single nucleotide polymorphism (SNP) of ERCC1, ERCC2, GGH, GSTP1, MTHFR, SLC19A1 and XRCC1 using single base primer extension assay.

RESULTS

The response to platinum-based NAC was higher in patients with SNP of XRCC1 R399Q (P=0.015), and there was a significant increased chance of treatment response in women with the G/G genotype (OR 38.0; 95% CI 1.66-870.45; P=0.023). The probability of response was also higher in patients with SNP of SLC19A1 6318C/T (P=0.032). There were dose-dependent influence of the number of alleles on the response to platinum-based chemotherapy (chi2 test for linear-by-linear association; P=0.009 for XRCC1 R399Q and P=0.017 for SLC19A1 6318C/T, respectively). Moreover, the multifactor dimensionality reduction (MDR) analysis documented that the combinations of XRCC1 R399Q and GGH-401C/T genetic polymorphisms were significantly associated with response to chemotherapy (P<0.0001).

CONCLUSIONS

Genetic polymorphism of XRCC1 R399Q is associated with response to platinum-based NAC in bulky cervical cancer, and MDR analysis documented association between gene-gene interaction of XRCC1 R399Q and treatment response.

Pharmacogenetics of colorectal cancer

Colorectal cancer is one of the most common types of cancer in both men and women. Multiple chemotherapy combinations exist; however, there is currently no strategy for individualised therapy selection prior to treatment. Genetic polymorphisms in genes involved in the metabolism, transport or targets for the commonly used chemotherapy drugs (5-fluorouracil, irinotecan and oxaliplatin) have been described. Many require validation in large prospective trials before they can be used as markers for outcome and/or toxicity. This review describes the data available on polymorphisms in key genes that are associated with chemotherapy toxicity and response in colorectal cancer.

Pharmacogenetic profiling and clinical outcome of patients with advanced gastric cancer treated with palliative chemotherapy

PURPOSE

To investigate whether polymorphisms with putative influence on fluorouracil/cisplatin activity are associated with clinical outcomes of patients with advanced gastric cancer (AGC).

PATIENTS AND METHODS

Peripheral blood samples from 175 prospectively enrolled AGC patients treated with fluorouracil/cisplatin palliative chemotherapy were used for genotyping 13 polymorphisms in nine genes (TS, MTHFR, XPD, ERCC1, XRCC1, XRCC3, GSTPI, GSTTI, GSTMI). Genotypes were correlated to response and survival.

RESULTS

The overall response rate was 41%, the median progression-free survival (PFS) was 24 weeks (range, 4 to 50 weeks), and the median overall survival (OS) was 39 weeks (range, 8 to 72+ weeks). Chemoresistance and poor survival were significantly associated with TS 5'-UTR 3G-genotype (2R/3G, 3C/3G, 3G/3G) and GSTP1 105 A/A homozygous genotype. Sixty-one patients (35%) did not show any of these risk genotypes (group 0), 57 patients (32.5%) showed one of the two risk genotypes (group 1), and 57 patients (32.5%) showed both risk genotypes (group 2). Median PFS and OS in group 0 patients were 32 weeks (range, 8 to 50 weeks) and 49 weeks (range, 18 to 72+ weeks), respectively. Group 1 and group 2 patients showed significantly worse PFS (median, 26 weeks [range, 6 to 44 weeks] and 14 weeks [range, 4 to 38 weeks], respectively) and worse OS (median, 39 weeks [range, 10 to 58 weeks] and 28 weeks [range, 8 to 56 weeks]), respectively, than group 0 patients. This adverse effect was retained in multivariate analysis.

CONCLUSION

Specific polymorphisms may influence clinical outcomes of AGC patients. Selecting palliative chemotherapy on the basis of pretreatment genotyping may represent an innovative strategy that warrants prospective studies.

Xeroderma pigmentosum group D haplotype predicts for response, survival, and toxicity after platinum-based chemotherapy in advanced nonsmall cell lung cancer

BACKGROUND

The treatment of lung cancer has reached a therapeutic plateau. Several mechanisms of platinum resistance have been described, including the removal of platinum-DNA adduct by nucleotide excision repair (NER). Polymorphisms within the Xeroderma pigmentosum Group D protein (XPD), a member of the NER pathway, are associated with alterations in enzyme activity and may change sensitivity to platinum-based chemotherapy. The authors investigated the relation between XPD polymorphisms and treatment response, toxicity, and overall survival in patients who received platinum-based chemotherapy for advanced nonsmall cell lung cancer (NSCLC).

METHODS

Between 2001 and 2002, 108 patients with chemotherapy-naive, advanced NSCLC were recruited. Associations between XPD312/751 polymorphisms and XPD haplotype and treatment response, toxicity. and survival were evaluated.

RESULTS

Significant correlations were observed between XPD haplotype and Grade 4 neutropenia and overall survival together with a greater response to platinum-based chemotherapy for the XPD *A haplotype.

CONCLUSIONS

The XPD haplotype may represent a useful pharmacogenomic marker of platinum-based chemotherapy in patients with advanced NSCLC and requires prospective validation.

Lack of association between DNA repair gene ERCC1 polymorphism and risk of lung cancer in a Chinese population

The ERCC1 (Excision Repair Cross Complementation Group 1) gene is involved in the nucleotide excision repair pathway. This study was designed to examine whether ERCC1 Asn118Asn (G19007A) polymorphism, which has been associated with risk of some cancers among Caucasians, may be associated with risk of lung cancer in a Chinese population. ERCC1 Asn118Asn (G19007A) genotypes were determined in DNA samples from 151 cases and 143 controls. The distribution of genotypes between cases and controls was not associated with an increased risk of lung cancer (AA versus GG: adjusted OR (odds ratio) = 1.41, 95% CI (confidence interval) = 0.76-2.59; AG versus GG: adjusted OR = 0.78, 95% CI = 0.47-1.29; and AA + AG versus GG: adjusted OR = 0.93, 95% CI = 0.73-1.19). The frequency A (0.20) of the A-allele was significantly lower among these Chinese controls than in the Caucasian control populations (A = 0.54-0.65) (All P < 0.001). No statistically significant effects of age, histological subtype or smoking were found. These findings suggest that ERCC1 Asn118Asn (G19007A) polymorphism may play a limited role for lung cancer in this Chinese population.

Polymorphisms in DNA repair genes modulate survival in cisplatin/gemcitabine-treated non-small-cell lung cancer patients

BACKGROUND

Impaired DNA repair capacity may favorably affect survival in cisplatin/gemcitabine-treated non-small-cell lung cancer (NSCLC) patients. We investigated the association of survival with genetic polymorphisms in X-ray repair cross-complementing group 1 and group 3 (XRCC3), xeroderma pigmentosum group D (XPD), excision repair cross-complementing group 1, ligase IV, ribonucleotide reductase, TP53, cyclooxygenase-2, interleukin-6, peroxisome proliferator-activated receptor gamma, epidermal growth factor, methylene-tetra-hydrofolate reductase and methionine synthase.

PATIENTS AND METHODS

One hundred and thirty-five stage IV or IIIB (with malignant pleural effusion) NSCLC patients treated with cisplatin/gemcitabine from different hospitals of the Spanish Lung Cancer Group were genotyped for 14 different polymorphisms in 13 genes. Polymorphisms were detected by the TaqMan method, using genomic DNA extracted from baseline blood samples.

RESULTS

Median survival was significantly increased in patients harboring XRCC3 241 MetMet: 16 months versus 10 months for patients with ThrMet and 14 months for those with ThrThr (P = 0.01). The risk of death ratio was significantly lower for MetMet than for ThrMet patients (hazard ratio, 0.43; P = 0.01). In the multivariate Cox model, XRCC3 241 remained an independent prognostic factor (hazard ratio: XRCC3 241 MetMet, 0.44; P = 0.01), and XPD 751 and XRCC1 399 also emerged as significant prognostic factors (hazard ratios: XPD 751 LysGln, 0.46, P = 0.03; XRCC1 399 ArgGln, 0.61, P = 0.04). No other association was observed between genotype and survival.

CONCLUSION

XRCC3 241 MetMet is an independent determinant of favorable survival in NSCLC patients treated with cisplatin/gemcitabine. A simple molecular assay to determine the XRCC3 241 genotype can be useful for customizing chemotherapy.

Polymorphisms/Haplotypes in DNA Repair Genes and Smoking: A Bladder Cancer Case-Control Study

Bladder cancer is associated with tobacco smoking and occupational exposure. The repair of DNA damage has a key role in protecting the genome from the insults of cancer-causing agents. We analyzed 13 polymorphisms in seven DNA repair genes belonging to different repair pathways [X-ray repair cross-complementing group 1 (XRCC1): 26304C>T, 26651A>G, 28152A>G; xeroderma pigmentosum-D (XPD): 23591A>G, 35931A>C; excision repair complementing defective in Chinese hamster, group 1 (ERCC1): 19007C>T; XRCC3: 4541T>C, 17893A>G, 18067C>T; proliferating cell nuclear antigen (PCNA): 6084G>C; ERCC4: 30028C>T, 30147A>G; and XRCC2-31479A>G] in 317 incident bladder cancer patients and 317 controls. After adjustment for age and smoking, the PCNA-6084C variant was significantly associated with an increased risk of bladder cancer [CC + CG versus GG, odds ratio (OR), 1.61; 95% confidence interval (95% CI), 1.00-2.61], as well as the XRCC1-26651G variant (GG+AG versus AA: OR, 1.73; 95% CI, 1.17-2.56). After stratifying by smoking habits, an elevated risk for carriers of the XRCC3-18067T allele was detected both in current (TT versus CC: OR, 2.65; 95% CI, 1.21-5.80; CT versus CC: OR, 1.96; 95% CI, 1.09-3.52) and never smokers (TT versus CC: OR, 4.34; 95% CI, 1.14-16.46; CT versus CC: OR, 2.02; 95% CI, 0.72-5.66), whereas an opposite and slightly weaker effect was associated to the XRCC3-17893G allele in current smokers (GG versus AA: OR, 0.30; 95%CI, 0.11-0.82; AG versus AA: OR, 0.73; 95% CI, 0.42-1.27). XRCC3,XRCC1, ERCC4, and XPD-ERCC1 haplotype frequencies were estimated by the maximum likelihood method. The XRCC3-TAT haplotype was associated with an enhanced risk in the current smokers group (OR, 1.62; 95% CI, 1.15-2.29), whereas a reduction of the risk in the overall sample was observed in the presence of the XRCC3-TAC (OR, 0.69; 95% CI, 0.50-0.97). A significant protective effect of the XPD-ERCC1-ACC haplotype was observed among never smokers (OR, 0.16; 95% CI, 0.03-0.81). Our results suggest that polymorphisms and/or haplotypes in XRCC3, XRCC1, and PCNA genes and spanning XPD-ERCC1 region may modulate bladder cancer risk and that some of these effects may preferentially affect current smokers.

ERCC1 codon 118 polymorphism is a predictive factor for the tumor response to oxaliplatin/5-fluorouracil combination chemotherapy in patients with advanced colorectal cancer

PURPOSE

The aim of our study was to assess whether the polymorphism of the nucleotide excision repair enzyme, excision repair cross-complementing rodent repair deficiency, complementation group 1 (ERCC1), had an effect on the tumor response in patients treated with standard chemotherapy regimens for a metastatic colorectal cancer. We have studied the synonymous polymorphism that causes a single nucleotide change C to T at codon 118 converting a codon of common usage (AAC) to a less used codon (AAT), both coding asparagine. This change results in a decreased ERCC1 gene expression, which impairs repair activity.

EXPERIMENTAL DESIGN

Ninety-one patients with a median age of 55.1 years treated for a metastatic colorectal cancer were included in our retrospective study. The ERCC1 polymorphism was analyzed in the normal tissue of all patients.

RESULTS

Twenty (22%) were homozygous for AAC codon (C/C genotype), 30 were (33%) homozygous for AAT codon (T/T genotype), and 41 (45%) were heterozygous (C/T genotype). The objective response rate to oxaliplatin in combination with 5-fluorouracil (5-FU) was significantly higher in the T/T genotype group compared with the C/T and the C/C genotype groups (61.9%, 42.3%, and 21.4%, respectively; P = 0.018). By contrast, no significant difference was observed when patients were treated with either 5-FU alone (45%, 29.2%, and 33.3%, respectively; P = 0.407) or in combination with irinotecan (46.1%, 25.0%, and 27.3%, respectively; P = 0.305).

CONCLUSIONS

Our observations allowed us to define the first useful predictive criterion for oxaliplatin/5-FU response in patients with metastatic colorectal cancer.

Pharmacogenetics for individualized cancer chemotherapy

The same doses of medication cause considerable heterogeneity in efficacy and toxicity across human populations. Genetic factors are thought to represent important determinants of drug efficacy and toxicity. Pharmacogenetics focuses on the prediction of the response of tumor and normal tissue to standard therapy by genetic profiling and, thereby, to select the most appropriate medication at optimal doses for each individual patient. In the present review, we discuss the relevance of single nucleotide polymorphisms (SNP) in genes, whose gene products act upstream of the actual drug target sites, that is, drug transporters and drug metabolizing phase I and II enzymes, or downstream of them, that is, apoptosis-regulating genes and chemokines. SNPs in relevant genes, which encode for proteins that interact with anticancer drugs, were also considered, that is, enzymes of DNA biosynthesis and metabolism, DNA repair enzymes, and proteins of the mitotic spindle. A significant body of evidence supports the concept of predicting drug efficacy and toxicity by SNP genotyping. As the efficacy of cancer chemotherapy, as well as the drug-related toxicity in normal tissues is multifactorial in nature, sophisticated approaches such as genome-wide linkage analyses and integrate drug pathway profiling may improve the predictive power compared with genotyping of single genes. The implementation of pharmacogenetics into clinical routine diagnostics including genotype-based recommendations for treatment decisions and risk assessment for practitioners represents a challenge for the future.

Polymorphisms of DNA Repair Genes: ERCC1 G19007A and ERCC2/XPD C22541A in a Northeastern Chinese Population

DNA repair systems are responsible for maintaining the integrity of the genome and have a critical role in protecting against mutations that can lead to cancer. DNA repair gene products of ERCC1 and ERCC2/XPD are involved in the nucleotide excision repair pathway. The allele frequencies of the polymorphisms ERCC1 G19007A and ERCC2/XPD C22541A were examined in a northeastern Chinese population. The allele frequencies were 0.21 (A) and 0.79 (G) for ERCC1 G19007A and 0.49 (A) and 0.51 (C) for ERCC2/XPD C22541A. Comparison with average frequencies from previously reported Caucasian studies demonstrated that the A-allele frequency of ERCC1 G19007A was much lower in the northeastern Chinese population, indicating a remarkable ethnic difference (chi((1)) (2) = 160.09, p < 0.001), and that allele frequencies of ERCC2/XPD C22541A showed marginal racial differences (chi((1)) (2) = 4.36, p = 0.04). We have previously reported that both homozygote carriers of the A-allele as well as homozygous carriers of a high-risk haplotype (which includes the AA genotype in ERCC1 G19007A) were at increased risk of basal cell carcinoma, breast cancer, and lung cancer among Caucasians. The low A-allele frequency of ERCC1 G19007A in the Chinese population may suggest that the genetic contribution to cancer risk differs substantially between ethnic groups.

Predicting drug response and toxicity based on gene polymorphisms

The sequencing of the human genome has allowed the identification of thousands of gene polymorphisms, most often single nucleotide polymorphims (SNP), which may play an important role in the expression level and activity of the corresponding proteins. When these polymorphisms occur at the level of drug metabolising enzymes or transporters, the disposition of the drug may be altered and, consequently, its efficacy may be compromised or its toxicity enhanced. Polymorphisms can also occur at the level of proteins directly involved in drug action, either when the protein is the target of the drug or when the protein is involved in the repair of drug-induced lesions. There again, these polymorphisms may lead to alterations in drug efficacy and/or toxicity. The identification of functional polymorphisms in patients undergoing chemotherapy may help the clinician prescribe the optimal drug combination or schedule and predict with more accuracy the response to these prescriptions. We have recorded in this review the polymorphisms that have been identified up till now in genes involved in anticancer drug activity. Some of them appear especially important in predicting drug toxicity and should be determined in routine before drug administration; this is the case of the most common variations of thiopurine methyltransferase for 6-mercaptopurine and of dihydropyrimidine dehydrogenase for fluorouracil. Other appear determinant for drug response, such as the common SNPs found in glutathione S-transferase P1 or xereoderma pigmentosum group D enzyme for the activity of oxaliplatin. However, confusion factors may exist between the role of gene polymorphisms in cancer risk or overall prognosis and their role in drug response.

Sarcomas and pharmacogenetics

Sarcomas are a heterogeneous group of tumors, requiring different chemotherapeutic approaches. Recently, several regimens for metastatic tumors were evaluated with respect to the different responses to conventional chemotherapy of the various histologic subtypes of sarcomas. The impact of pharmacogenetics in the progress of chemotherapy appears to be crucial in defining the clinical response to many drugs, such as anthracycline or alkylating agents, that are widely used in treatment regimens for soft tissue sarcomas (STS) or sarcomas of the bone. Polymorphisms of metabolizing enzymes (e.g., cytochrome P450 and glutathione-S-transferase), transporter proteins (reduced folate carrier and P-glycoprotein) or target proteins (thymidylate synthase, methylenetetrahydrofolate reductase, dihydrofolate reductase, and c-KIT) may be responsible for an altered clinical outcome, in terms of both response and toxicity. The administration of new chemotherapeutic agents, such as imatinib for gastrointestinal tumors (GIST), requires the study of genetic polymorphisms possibly affecting the integrity of the target (c-KIT), which may provide valid information regarding possible developments of therapy. For STS and sarcoma of the bone, the genetic markers, which could be unambiguously predictive of the phenotypic profile of patients, are as yet undetermined.

High mutagen sensitivity in peripheral blood lymphocytes predicts poor overall and disease-specific survival in patients with stage III non-small cell lung cancer treated with radiotherapy and chemotherapy

PURPOSE

To investigate whether the bleomycin sensitivity assay, an in vitro peripheral blood lymphocyte assay, can predict outcome in patients with inoperable stage III non-small-cell lung cancer (NSCLC) treated with definitive radiotherapy and chemotherapy.

EXPERIMENTAL DESIGN

We identified 102 patients with inoperable stage III NSCLC cell lung cancer treated with definitive radiotherapy and chemotherapy. The patients' pretreatment peripheral blood lymphocyte cultures were treated with the radiomimetic mutagen bleomycin. An index of bleomycin sensitivity was determined by counting the number of chromatid breaks in 50 metaphases. The correlation between bleomycin sensitivity (expressed as mean breaks per cell) and clinical outcome was analyzed.

RESULTS

High bleomycin sensitivity (defined as a mean of >1.02 chromatid breaks/cell, representing the third quartile of bleomycin sensitivity) predicted poor disease-specific survival and overall survival. The 6-year disease-specific survival was 27% in patients with high bleomycin sensitivity compared with 46% in patients without such sensitivity (P = 0.0094). The association remained statistically significant when adjusted for smoking status, age, and radiation dose. The 6-year overall survival was 19% for patients with high bleomycin sensitivity and 29% for those without (P = 0.0193). There was a trend toward worse local regional control and worse disease-free survival among patients with high bleomycin sensitivity. There was no difference between the two groups in distant metastasis-free survival or radiation treatment-related complications.

CONCLUSIONS

High bleomycin sensitivity correlated with poor overall survival and disease-specific survival in these patients with stage III NSCLC treated with radiotherapy and chemotherapy. Bleomycin sensitivity may function as a biomarker for poor clinical outcome for this group of patients.

Predictors of the response to gefitinib in refractory non-small cell lung cancer

Gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has a response rate of 10% to 20% in refractory non-small cell lung carcinoma. Although female gender, adenocarcinoma, and never having smoked are possible markers of a favorable response, mutations of the EGFR gene have also been reported to be highly significant predictors of response. Seventy patients with relapsed non-small cell lung carcinoma were enrolled in the Expanded Access Program. After the drug became available commercially, 28 more patients were treated with gefitinib. Response evaluations were feasible in 80 patients. Twenty-seven tumor specimens (8 responders and 19 nonresponders) were available for the sequence analysis of the EGFR gene. The response rate was 25% (20/80) and the disease control rate (remission + stable disease) was 47.5% (38/80). The response rate was significantly higher for adenocarcinoma (41.0%) versus non-adenocarcinoma (9.8%, P = 0.001), in those who never smoked (58.8%) versus smokers (15.9%, P < 0.001), and in females (42.1%) versus males (19.7%, P = 0.049). A deletion or mutation of the EGFR gene was found in six of eight responders. Remission was noted in all patients with a mutation, whereas the response rate was 9.5% (2/21) in patients without a mutation (P < 0.001). The predictors of response showed significant correlations with survival and time to progression. In a multivariate logistic analysis, the independent predictors of response were smoking history and adenocarcinoma. Given that 9.5% of smokers and 6.7% of those with non-adenocarcinoma showed a mutation of the EGFR gene, the genetic profile may replace those variables as an independent predictor of a response.

Nucleotide excision repair as a marker for susceptibility to tobacco-related cancers: a review of molecular epidemiological studies

DNA repair is a complicated biological process consisting of several distinct pathways that play a central role in maintaining genomic stability. Research on DNA repair and cancer risk is a vital, emerging field that recently has seen rapid advances facilitated by the completion of the Human Genome Project. In this review, we described phenotypic and genotypic markers of nucleotide excision repair (NER) that have been used in molecular epidemiology studies. We summarized the population-based studies to date that have examined the association between DNA repair capacity phenotype and genetic polymorphisms of the NER genes and risk of tobacco-related cancers, including cancers of the lung, head and neck, prostate, bladder, breast, and esophagus. We also included studies of melanoma and nonmelanoma skin cancers because individuals with defective NER, such as patients with xeroderma pigmentosum (XP) are highly susceptible to ultraviolet light (UV)-induced melanoma and nonmelanoma skin cancers. The published data provide emerging evidence that DNA repair capacity may contribute to genetic susceptibility to cancers in the general population. However, many of the studies are limited in terms of the size of the study populations. Furthermore, all published findings are still considered preliminary, the assays used in the studies have yet to be validated, and the results need to be confirmed. Large and well-designed population-based studies are warranted to assess gene-gene and gene-environment interactions and to ultimately determine, which biomarkers of DNA repair capacity are useful for screening high-risk populations for primary prevention and early detection of tobacco-related cancers.

Expression of a splicing variant in the 5′-UTR of the human ERCC1 gene is not cancer related

Cisplatin is the most commonly used chemotherapeutic agent in the treatment of ovarian cancer. One of the mechanisms of resistance of ovarian tumours to cisplatin is increased nucleotide excision repair activity, in particular increased levels of the endonuclease ERCC1. Since 30-40% of ovarian cancers develop resistance to cisplatin after treatment and these tumours are usually incurable, ERCC1 expression is potentially useful as a predictive marker for the effectiveness of cisplatin-based chemotherapy. Using RT-PCR and Northern blotting, we have examined the expression of a 42 bp differentially spliced sequence in exon 1 of the human ERCC1 gene, loss of which has previously been reported to be correlated with higher levels of ERCC1 mRNA in ovarian cancer cell lines. We report here that this alternate transcript is ubiquitous in human tissues and cancer cell lines, is absent in mouse and thus does not appear to be cancer related.