Polymorphisms in p53, GSTP1 and XRCC1 predict relapse and survival of gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy

Understanding and targeting resistance mechanisms in cancer

Resistance to cancer therapies has been a commonly observed phenomenon in clinical practice, which is one of the major causes of treatment failure and poor patient survival. The reduced responsiveness of cancer cells is a multifaceted phenomenon that can arise from genetic, epigenetic, and microenvironmental factors. Various mechanisms have been discovered and extensively studied, including drug inactivation, reduced intracellular drug accumulation by reduced uptake or increased efflux, drug target alteration, activation of compensatory pathways for cell survival, regulation of DNA repair and cell death, tumor plasticity, and the regulation from tumor microenvironments (TMEs). To overcome cancer resistance, a variety of strategies have been proposed, which are designed to enhance the effectiveness of cancer treatment or reduce drug resistance. These include identifying biomarkers that can predict drug response and resistance, identifying new targets, developing new targeted drugs, combination therapies targeting multiple signaling pathways, and modulating the TME. The present article focuses on the different mechanisms of drug resistance in cancer and the corresponding tackling approaches with recent updates. Perspectives on polytherapy targeting multiple resistance mechanisms, novel nanoparticle delivery systems, and advanced drug design tools for overcoming resistance are also reviewed.

Characteristics and response to next-generation sequencing-guided therapy in locally advanced or metastatic esophageal cancer

Esophageal cancer (EC) is a main cause of cancer-related deaths. However, genomic alterations and the clinical value of next-generation sequencing (NGS) in advanced or metastatic EC for precision therapy remain largely unclear. Herein, we performed comprehensive analyses on a cohort of 47 individuals with advanced or metastatic EC who underwent NGS between May 2017 and February 2020. Eventually, 227 mutated genes were identified in the cohort. TP53, NQO1, DPYD, GSTM1, XRCC1 and ERCC1 were the most mutated genes and associated with immune cell infiltration, autophagy and hypoxia. Patients who received NGS-guided treatments exhibited better objective remission rate (ORR) (72.22%), disease control rate (DCR) (88.89%), overall survival (OS) (P = .0019) and progression-free survival (PFS) (P = .0077) than those not receiving NGS-guided therapies. The multivariate analyses further demonstrated that the NGS-guided therapy was an independently prognostic factor (OS: hazard radio [HR] 0.31, 95% coincidence interval [CI] 0.1-0.97, P = .04). In conclusion, we depicted a comprehensive mutational landscape of 47 patients with locally advanced or metastatic EC and illustrated the utility of NGS testing to guide clinical management in improving ORR, DCR, OS and PFS.

SP1-induced lncRNA DUBR promotes stemness and oxaliplatin resistance of hepatocellular carcinoma via E2F1-CIP2A feedback

Oxaliplatin-based chemotherapy is widely used to treat advanced hepatocellular carcinoma (HCC), but many patients develop drug resistance that leads to tumor recurrence. Cancer stem cells (CSCs) are known to contribute to chemoresistance, the underlying mechanism, however, remains largely unknown. In this study, we discovered a specificity protein 1 (SP1)-induced long noncoding RNA--DPPA2 upstream binding RNA (DUBR) and its high expression in HCC tissues and liver CSCs. DUBR was associated with HCC progression and poor chemotherapy response. Moreover, DUBR facilitated the stemness and oxaliplatin resistance of HCC in vitro and in vivo. Mechanistically, DUBR upregulated cancerous inhibitor of protein phosphatase 2A (CIP2A) expression through E2F1-mediated transcription regulation. DUBR also exerted function by binding microRNA (miR)-520d-5p as a competing endogenous RNA to upregulate CIP2A at mRNA level. CIP2A, in turn, stabilized E2F1 protein and activated the Notch1 signaling pathway, thereby increasing the stemness feature of HCC and leading to chemoresistance. In conclusion, we identified SP1/DUBR/E2F1-CIP2A as a critical axis to activate the Notch1 signaling pathway and promote stemness and chemoresistance of HCC. Therefore, DUBR could be a potential target in HCC treatment.

Isoforms of the p53 Family and Gastric Cancer: A Ménage à Trois for an Unfinished Affair

Simple Summary

The p53 family is a complex family of transcription factors with different cellular functions that are involved in several physiological processes. A massive amount of data has been accumulated on their critical role in the tumorigenesis and the aggressiveness of cancers of different origins. If common features are observed, there are numerous specificities that may reflect particularities of the tissues from which the cancers originated. In this regard, gastric cancer tumorigenesis is rather remarkable, as it is induced by bacterial and viral infections, various chemical carcinogens, and familial genetic alterations, which provide an example of the variety of molecular mechanisms responsible for cell transformation and how they impact the p53 family. This review summarizes the knowledge gathered from over 40 years of research on the role of the p53 family in gastric cancer, which still displays one of the most elevated mortality rates amongst all types of cancers.

Abstract

Gastric cancer is one of the most aggressive cancers, with a median survival of 12 months. This illustrates its complexity and the lack of therapeutic options, such as personalized therapy, because predictive markers do not exist. Thus, gastric cancer remains mostly treated with cytotoxic chemotherapies. In addition, less than 20% of patients respond to immunotherapy. TP53 mutations are particularly frequent in gastric cancer (±50% and up to 70% in metastatic) and are considered an early event in the tumorigenic process. Alterations in the expression of other members of the p53 family, i.e., p63 and p73, have also been described. In this context, the role of the members of the p53 family and their isoforms have been investigated over the years, resulting in conflicting data. For instance, whether mutations of TP53 or the dysregulation of its homologs may represent biomarkers for aggressivity or response to therapy still remains a matter of debate. This uncertainty illustrates the lack of information on the molecular pathways involving the p53 family in gastric cancer. In this review, we summarize and discuss the most relevant molecular and clinical data on the role of the p53 family in gastric cancer and enumerate potential therapeutic innovative strategies.

Glutathione S-transferases genes variants and chemotherapy efficacy in gastrointestinal cancer patients: a meta-analysis based on 50 pharmacogenetic studies

Background: The role of glutathione s-transferase genes (GSTP1, GSTM1 and GSTT1) variants and the GSTP1 expression level on chemotherapy efficacy of gastrointestinal cancer (GIC) patients were inconsistent. Methods: A meta-analysis about GSTP1, GSTM1 and GSTT1 variants and the GSTP1 expression level on chemotherapy efficacy of GIC patients was performed using data from PubMed, PMC, EMBASE, Web of Science, and Wanfang database. Results: Our meta-analysis enrolled 50 publications including 6518 patients. We found that patients with GIC harboring GSTP1 (IIe105Val) Val locus had higher objective response rates (ORR) than the IIe/IIe genotypic patients (odds ratio (OR) = 1.580, 95% confidence interval (CI) = 1.159-2.154, P = 0.004). Significant associations were found between the Ile105Val variant and overall survival of Caucasian GIC patients (IIe/Val vs. IIe/IIe: OR = 0.797 (0.674-0.944), P = 0.009). Caucasian GIC patients and gastric cancer patients with GSTT1 null genotype had worse response rates compared to GSTT1 present patients (OR = 0.530 (0.356-0.789), P = 0.002; OR = 0.643 (0.463-0.895), P = 0.009, respectively). Conclusion: This meta-analysis illustrates that GSTP1 IIe105Val and GSTT1 null/present variants could be useful predictors of chemotherapy efficacy in patients with gastrointestinal cancer.

Demethoxycurcumin-Loaded Chitosan Nanoparticle Downregulates DNA Repair Pathway to Improve Cisplatin-Induced Apoptosis in Non-Small Cell Lung Cancer

Demethoxycurcumin (DMC), through a self-assembled amphiphilic carbomethyl-hexanoyl chitosan (CHC) nanomatrix has been successfully developed and used as a therapeutic approach to inhibit cisplatin-induced drug resistance by suppressing excision repair cross-complementary 1 (ERCC1) in non-small cell lung carcinoma cells (NSCLC). Previously, DMC significantly inhibited on-target cisplatin resistance protein, ERCC1, via PI3K-Akt-snail pathways in NSCLC. However, low water solubility and bioavailability of DMC causes systemic elimination and prevents its clinical application. To increase its bioavailability and targeting capacity toward cancer cells, a DMC-polyvinylpyrrolidone core phase was prepared, followed by encapsulating in a CHC shell to form a DMC-loaded core-shell hydrogel nanoparticles (DMC-CHC NPs). We aimed to understand whether DMC-CHC NPs efficiently potentiate cisplatin-induced apoptosis through downregulation of ERCC1 in NSCLC. DMC-CHC NPs displayed good cellular uptake efficiency. Dissolved in water, DMC-CHC NPs showed comparable cytotoxic potency with free DMC (dissolved in DMSO). A sulforhodamine B (SRB) assay indicated that DMC-CHC NPs significantly increased cisplatin-induced cytotoxicity by highly efficient intracellular delivery of the encapsulated DMC. A combination of DMC-CHC NPs and cisplatin significantly inhibited on-target cisplatin resistance protein, ERCC1, via the PI3K-Akt pathway. Also, this combination treatment markedly increased the post-target cisplatin resistance pathway including bax, and cytochrome c expressions. Thymidine phosphorylase (TP), a main role of the pyrimidine salvage pathway, was also highly inhibited by the combination treatment. The results suggested that enhancement of the cytotoxicity to cisplatin via administration of DMC-CHC NPs was mediated by down-regulation of the expression of TP, and ERCC1, regulated via the PI3K-Akt pathway.

The Profile of Serum microRNAs Predicts Prognosis for Resected Gastric Cancer Patients Receiving Platinum-Based Chemotherapy

BACKGROUND AND AIM

Adjuvant chemotherapy is an important component in the treatment of gastric cancer (GC) patients; however, some patients do not respond to the drugs. We aimed to develop a practical profile based on serum microRNAs (miRNAs) that can be used to predict patients likely to respond to treatment.

METHODS

Microarrays were used to screen cisplatin-resistant SGC7901/DDP GC cells and the parental SGC7901 cell lines for miRNAs related to chemotherapy sensitivity. The correlation between the expression patterns of identified serum miRNAs and overall survival was confirmed in 68 GC patients. Furthermore, we also validated the signature of the serum miRNAs in an independent cohort of 50 GC patients.

RESULTS

From the screening microarrays, we focused on miR-15a, miR-15b and miR-93 as downregulated miRNAs in the SGC7901/DDP cells and miR-27a, miR-106a and miR-664 as upregulated miRNAs. Only serum miR-106, miR-15a, miR-93 and miR-664 were useful in predicting the prognosis of patients who received adjuvant chemotherapy. We identified a signature of four serum miRNAs (miR-106, miR-15a, miR-93 and miR-664) that, when combined, can be used as a risk score for overall survival. Patients with a higher risk score had worse prognosis (p < 0.05). For the independent cohort of patients, the signature of the four miRNAs predicted prognosis well.

CONCLUSION

Our data showed that the risk score derived from the four serum miRNAs was closely associated with the overall survival in GC patients who received adjuvant chemotherapy.

Predictive role of GSTP1-containing exosomes in chemotherapy-resistant breast cancer

Anthracycline/taxane-based chemotherapy regimens are usually used as neoadjuvant chemotherapies to decrease tumour size and prevent metastasis of advanced breast cancer. However, patients have a high risk of developing chemo-resistance during treatment through still unknown mechanisms. Glutathione S-transferase P1 (GSTP1), which belongs to the family of phase II metabolic enzymes, has been reported to function in detoxifying several anti-cancer drugs by conjugating them with glutathione. Previous studies have identified GSTP1 as a predictor of prognosis and chemo-resistance in breast cancer patients, but the mechanisms governing GSTP1-dependent drug resistance are still unclear. We have found that GSTP1 expression is much higher in adriamycin-resistant cells and their corresponding exosomes. The role of GSTP1-containing exosomes in conferring drug resistance was analysed through cell apoptosis and immunofluorescence staining assays. Furthermore, we analysed 42 cases of paired breast cancer tissues collected before and after anthracycline/taxane-based neoadjuvant chemotherapy by immunohistochemistry. Higher GSTP1 expression was shown in the progressive disease (PD)/stable disease (SD) group than in the partial response (PR)/complete response (CR) group both in the samples collected before and after the chemotherapy treatment. Interestingly, GSTP1 partly re-localized from the cell nucleus to the cytoplasm upon treatment, and similar results were obtained for the exosomal marker Tumour susceptibility gene 101 protein (TSG101), which also increased in the cytoplasm after chemotherapy. After analysing the serum exosomes of 30 patients treated with anthracycline/taxane-based neoadjuvant chemotherapy, we discovered that the levels of GSTP1 in exosomes from patients in the PD/SD group were significantly higher than those in the PR/CR group. Here, for the first time, we investigated a novel role for GSTP1-containing exosomes and their capability to transfer drug resistance and evaluated their clinical use in predicting chemo-resistance.

Can GSTM1 and GSTT1 polymorphisms predict clinical outcomes of chemotherapy in gastric and colorectal cancers? A result based on the previous reports

Background

Gastric and colorectal cancers remain the major causes of cancer-related death. Although chemotherapy improves the prognosis of the patients with gastrointestinal cancers, some patients do not benefit from therapy and are exposed to the adverse effects. The polymorphisms in genes including GSTM1 and GSTT1 have been explored to predict therapeutic efficacy; however, the results were inconsistent and inconclusive.

Materials and methods

A systematic review and meta-analysis was performed by searching relevant studies about the association between the GSTM1 and GSTT1 polymorphisms and chemotherapy efficacy in gastrointestinal cancers in databases such as PubMed, EMBASE, Web of Science, Chinese National Knowledge Infrastructure, and Wanfang database up to January 10, 2016. Subgroup analyses were also performed according to ethnicity, cancer type, evaluation criteria, study type, chemotherapy type, and age.

Results

A total of 19 articles containing 3,217 cases were finally included. Overall analysis suggested that no significance was found between overall toxicity, neurotoxicity, neutropenia, gastrointestinal toxicity, tumor response, and progression-free survival, and the polymorphisms in GSTM1 and GSTT1, while GSTM1 polymorphism associated with overall survival (OS; hazard ratio =1.213, 95% confidence interval =1.060–1.388, P=0.005). Subgroup analyses suggested that neurotoxicity was associated with GSTM1 polymorphism in the Asian population, neutropenia was associated with GSTM1 polymorphism in palliative chemotherapy and older patients (mean age >60 years), and tumor response was associated with GSTT1 polymorphism in gastric cancer and responders defined by complete and partial responses. Meanwhile, GSTM1 was associated with OS in Caucasians, Asians, those with colorectal cancer, and patients with mean age <60 years. GSTT1 polymorphism was also associated with OS in Caucasians and patients with mean age >60 years.

Conclusion

The polymorphisms in GSTM1 and GSTT1 did not associate with the chemotherapy-related toxicity in gastrointestinal cancers, while GSTT1 polymorphism associated with OS, and further well-designed, larger-scale epidemiological studies are needed to validate our results.

Predictive value of GSTP1 Ile105Val polymorphism in clinical outcomes of chemotherapy in gastric and colorectal cancers: a systematic review and meta-analysis

PURPOSE

Gastric and colorectal cancers remain the major causes of cancer-related death with a bad prognosis. Up to now, platinum combined with fluoropyrimidines has been most commonly used in chemotherapy regimens of gastric and colorectal cancers. Recently, a series of studies have been conducted to investigate the associations of biomarkers, such as GSTP1 Ile105Val polymorphism, with the chemotherapy efficacy in gastric and colorectal cancers; however, the results were not consistent and inconclusive. Here, we performed a systematic review and meta-analysis to summarize the associations of GSTP1 Ile105Val polymorphism with the chemotherapy efficacy in gastric and colorectal cancers.

METHODS

A systematic review was conducted to search relevant studies in English databases (PubMed, ISI Web of Science, and EMBASE) up to November 30, 2015. The pooling ORs or HRs were used to assess the strength of the associations of GSTP1 Ile105Val polymorphism with clinical outcomes such as tumor response, toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

Forty-one papers containing 8169 cases were finally included in the present meta-analysis study. Of which, 28 articles were performed in colorectal cancers, one in gastrointestinal carcinoma (gastric and colon cancer), 11 in gastric cancers, and one in colorectal and gastroesophageal cancers. After pooling all the eligible studies, we identified significant associations of GSTP1 Ile105Val polymorphism with chemotherapy-related tumor response (G vs. A: OR 1.697, 95 % CI 1.191-2.418; GG vs. AA: OR 2.804, 95 % CI 1.414-5.560; AG vs. AA: OR 1.540, 95 % CI 1.011-2.347; GG vs. AAAG: OR 2.139, 95 % CI 1.256-3.641), PFS (GG vs. AA, HR 0.640, 95 % CI 0.455-0.900; AGGG vs. AA: HR 0.718, 95 % CI 0.562-0.919), and OS (AG vs. AA: HR 0.857, 95 % CI 0.746-0.986; GG vs. AA: HR 0.679, 95 % CI 0.523-0.882; AGGG vs. AA: HR 0.663, 95 % CI 0.542-0.812) in gastric and colorectal cancers and no significant association was found between the polymorphism with toxicity.

CONCLUSIONS

GSTP1 Ile105Val polymorphism was associated with tumor response, PFS, and OS in gastric and colorectal cancers after chemotherapy.

Influences of ERCC1, ERCC2, XRCC1, GSTP1, GSTT1, and MTHFR polymorphisms on clinical outcomes in gastric cancer patients treated with EOF chemotherapy

This study investigated the associations between genetic polymorphisms of six genes involved in DNA repair, detoxification pathways, and fluoropyrimidine metabolism and clinical outcomes in MGC patients receiving EOF treatment. This retrospective study included 108 Chinese MGC patients receiving EOF as first-line chemotherapy. Nine single nucleotide polymorphisms (SNPs) of six genes (ERCC1 rs2298881, ERCC2 rs13181 and rs1799793, XRCC1 rs25487 and rs25489, GSTP1 rs1695, GSTT1 rs2266637, and MTHFR rs1801133 and rs1801131) were genotyped, and the associations between each SNP and clinical outcome were analyzed. XRCC1 rs25487 A allele was significantly associated with progression disease (PD) to EOF (p = 0.002), and patients with AA genotype had significantly poorer progression-free survival (PFS) (p = 0.001) and overall survival (OS) (p = 0.041) compared with patients with the G allele (GG + GA). ERCC2 rs13181 G allele was significantly associated with PD (p = 0.026), and G carriers (GG + GT) tended to have poorer PFS (p = 0.092) than TT homozygotes. ERCC2 rs1799793 GA genotype was associated with unfavorable PFS (p = 0.034) and a tendency toward poorer OS (p = 0.090) compared with GG homozygotes. Patients were categorized as either good (0 risk factors) or poor risk (≥1 unfavorable SNPs) using a prognostic index based on XRCC1 rs25487 AA, ERCC2 rs13181 (GG + GT), and ERCC2 rs1799793 GA genotypes, with median OS and PFS of 534 days, 281 days (p = 0.009) and 206 days, and 123 days (p < 0.001), respectively. These results suggest that the prognostic index comprising XRCC1 rs25487, ERCC2 rs13181, and rs1799793 polymorphisms may be a useful predictor of clinical outcomes in MGC treated with EOF.

Tumor-Related Molecular Mechanisms of Oxaliplatin Resistance

Oxaliplatin was the first platinum drug with proven activity against colorectal tumors, becoming a standard in the management of this malignancy. It is also considered for the treatment of pancreatic and gastric cancers. However, a major reason for treatment failure still is the existence of tumor intrinsic or acquired resistance. Consequently, it is important to understand the molecular mechanisms underlying the appearance of this phenomenon to find ways of circumventing it and to improve and optimize treatments. This review will be focused on recent discoveries about oxaliplatin tumor-related resistance mechanisms, including alterations in transport, detoxification, DNA damage response and repair, cell death (apoptotic and nonapoptotic), and epigenetic mechanisms.

Association between the ERCC1 rs11615 polymorphism and clinical outcomes of oxaliplatin-based chemotherapies in gastrointestinal cancer: a meta-analysis

Purpose

The relationship between the excision repair cross-complementing 1 (ERCC1) rs11615 polymorphism (C/T) and responses to oxaliplatin-based chemotherapy for gastric cancer (GC) and colorectal cancer (CRC) patients is controversial. Therefore, we performed a meta-analysis to assess this relationship.

Method

Relevant studies were retrieved by searching the PubMed database. A systematic review and meta-analysis was performed to evaluate the predictive value of the ERCC1 rs11615 polymorphism for the clinical outcomes of GC and CRC patients receiving oxaliplatin-based chemotherapy. Therapeutic response to chemotherapy, progression-free survival (PFS), and overall survival (OS) were analyzed.

Results

A total of 22 studies were included in this meta-analysis, including 1,242 cases of GC and 1,772 cases of CRC. For the ERCC1 rs11615 polymorphism, the T allele was associated with a reduced response to chemotherapy in Asians and GC patients (P<0.05). On the other hand, the T allele was associated with a significant increase in the risk for shorter PFS and OS in all patients (PFS: hazard ratio [HR] =1.22, P<0.001, 95% confidence interval [CI] =0.93–1.51 and OS: HR =1.12, P<0.001, 95% CI =0.85–1.40).

Conclusion

The ERCC1 rs11615 polymorphism was closely associated with the clinical outcomes of GC and CRC patients treated with oxaliplatin-based chemotherapy.

Perspectives on new biomarkers in gastric cancer: Diagnostic and prognostic applications

Gastric cancer is considered one of the most deadly tumors worldwide. Even with the decline in its incidence, the mortality rate of this disease has remained high, mainly due to its late diagnosis and to the lack of precise prognostic markers. The main purpose of this review is to present genetic, epigenetic and proteomic molecular markers that may be used in a diagnostic and prognostic manner and to discuss the pros and cons of each type of marker for improving clinical practice. In this sense, we observed that the use of genetic markers, especially mutations and polymorphisms, should be carefully considered, as they are strongly affected by ethnicity. Proteomic-based markers show promise, but the higher costs of the associated techniques continue to make this approach expensive for routine use. Alternatively, epigenetic markers appear to be very promising, as they can be detected in bodily fluids as well as tissues. However, such markers must be used carefully because epigenetic changes may occur due to environmental factors and aging. Despite the advances in technology and its access, to date, there are few defined biomarkers of prognostic and diagnostic use for gastric tumors. Therefore, the use of a panel of several approaches (genetic, epigenetic and proteomic) should be considered the best alternative for clinical practice.

Nucleotide excision repair related gene polymorphisms and genetic susceptibility, chemotherapeutic sensitivity and prognosis of gastric cancer

Human genomic DNA is in a dynamic balance of damage and repair. Cells employ multiple and specific repair pathways, such as nucleotide excision repair (NER), as unrepaired DNA damage has deleterious consequences and could give rise to carcinogenesis. Gene polymorphisms play a crucial role in predicting the risk and prognosis of cancer. Polymorphisms of NER-related genes could alter the ability of NER to effectively monitor and repair DNA damage, and thus may be associated with genetic susceptibility, chemotherapeutic sensitivity and prognosis of cancer. In recent years, increasing studies have focused on the association between polymorphisms of NER genes and gastric cancer, the world's fourth most common cancer and the second most common cause for cancer-related death. Here we reviewed the recent studies on the associations between polymorphisms of NER genes and gastric cancer from perspectives of genetic susceptibility, chemotherapeutic sensitivity and prognosis.

ERCC1 siRNA ameliorates drug resistance to cisplatin in gastric carcinoma cell lines

The present study examined the effects of cisplatin (DDP) on gastric carcinoma cells by inhibiting the expression of excision repair cross-complementing 1 (ERCC1) using RNA interference (RNAi). mRNA and protein expression of ERCC1 were measured in various gastric carcinoma cell lines using reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis. Cells were treated with different concentrations of DDP and the cell viability was measured using an MTT assay. The correlation between the expression of the ERCC1 gene and the resistance to DDP in the cells was determined. The specific ERCC1 small interfering RNA (siRNA) was synthesized and then transfected into SGC-7901/DDP cells. Alterations in intracellular ERCC1 mRNA expression and protein levels were detected using RT-PCR and western blot analysis, the number of apoptotic cells were measured using flow-cytometry and the cell viability was measured using an MTT assay. The gene expression of ERCC1 correlated with the resistance to DDP of the cells. mRNA expression of ERCC1 was significantly reduced 24 h following transfection of ERCC1 siRNA compared with the mock control group. In addition, the number of apoptotic cells was increased and cell viability was significantly decreased in the ERCC1 siRNA-transfected group compared with the mock control group, suggesting that the sensitivity of SGC-7901/DDP cells to DDP had significantly increased. Cells transfected with siRNA1, siRNA2 and siRNA3 were significantly more sensitive to DPP (161, 381 and 249%, respectively) compared with the mock controls (P<0.05). The results of the present study showed that drug resistance to DDP in gastric carcinoma is correlated with increased expression of ERCC1; therefore, inhibition of ERCC1 by siRNA may ameliorate resistance to DDP in gastric carcinoma.

XRCC1 and XPD genetic polymorphisms and clinical outcomes of gastric cancer patients treated with oxaliplatin-based chemotherapy: a meta-analysis

This meta-analysis aimed to obtain a comprehensive and reliable assessment of the relationships between XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms and the clinical outcomes of gastric cancer (GC) patients treated with oxaliplatin-based chemotherapy. The PubMed, CINAHL, Web of Science, CISCOM, EBSCO, Google Scholar, Cochrane Library, and CBM databases were searched for relevant articles published before September 1, 2013 without language restrictions. Crude odd ratios (ORs) or hazard risk (HR) [95 % confidence intervals (CI)] were calculated. Twelve clinical cohort studies were assessed with a total 1,024 GC patients treated with oxaliplatin-based chemotherapy. Our meta-analysis findings revealed that GC patients with the GA+AA (A carrier) genotypes of XRCC1 Arg399Gln showed a lower effective clinical response (CR+PR) than those with the GG (A non-carrier) genotype (OR=0.41, 95 % CI 0.20∼0.82, P=0.012). However, there was no statistically significant difference in effective clinical response between those with XPD AC+CC (C carrier) genotypes and CC (C non-carrier) genotype (OR=0.55, 95 % CI 0.28∼1.07, P=0.076). Furthermore, the GA+AA genotypes of XRCC1 Arg399Gln was associated with a worse progression-free survival (PFS) and overall survival (OS) compared with the CC genotype (PFS, HR=1.90, 95 % CI 1.12∼2.69, P<0.001; OS, HR=2.13, 95 % CI 0.79∼3.47, P=0.002, respectively). No relationships were found between XPD Lys751Gln polymorphism and both PFS and OS (all P>0.05). No publication bias was detected in this meta-analysis. Results from the current meta-analysis indicate that XRCC1 Arg399Gln polymorphism may be associated with poor clinical outcomes in GC patients treated with oxaliplatin-based chemotherapy.

Association between polymorphisms in XRCC1 gene and treatment outcomes of patients with advanced gastric cancer: a systematic review and meta-analysis

Background

Many reports have shown inconsistent results on the relationship between single nucleotide polymorphisms (SNPs) of X-ray repair cross complementing protein (XRCC1) gene and platinum-based chemotherapeutic efficacy. This meta-analysis aimed to summarize published data about the association between two SNPs of XRCC1 (Arg194Trp and Arg399Gln) and treatment outcomes of patients with advanced gastric cancer.

Methodology/Principal Findings

We retrieved the relevant articles from MEDLINE, Web of Knowledge, and the China National Knowledge Infrastructure (CNKI) databases. Studies were selected according to specific inclusion and exclusion criteria. Study quality was assessed according to the guidelines outlined by Hayden, et al. and PRISMA guidelines. We estimated the odds ratio (OR) for response rate versus no response after platinum-based chemotherapy. Progression-free survival (PFS) and overall survival (OS) were evaluated by pooled Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs). We found that none of the XRCC1 Arg194Trp and Arg399Gln polymorphisms was significantly associated with tumor response. Stratified analysis by ethnicity or sensitivity analysis also showed that XRCC1 SNPs were not related with chemotherapy response. Patients with minor variant A allele were likely to have poorer 2-year survival rate than those with G/G genotype. However, in the group of 5-year follow up, there was no significant association between the A allele and OS yet.

Conclusions/Significance

There is no evidence to support the use of XRCC1 Arg194Trp and Arg399Gln polymorphisms as prognostic predictors of TR and PFS in gastric patients treated with platinum-based chemotherapy. The relationship between minor variant A allele and OS requires further verification.

Genetic polymorphisms of ERCC1‑118, XRCC1‑399 and GSTP1‑105 are associated with the clinical outcome of gastric cancer patients receiving oxaliplatin‑based adjuvant chemotherapy

The aim of the present study was to determine whether specific molecular parameters may serve as predictors of treatment outcomes and toxicity of oxaliplatin (OXA)‑based chemotherapy, which is used as an adjuvant treatment in resected gastric cancer. All gastric cancer patients examined in the study received an OXA/5‑fluorouracil chemotherapeutic regimen. Genetic polymorphisms of certain platinum‑related genes were determined by the TaqMan 5' nuclease assay and direct sequencing. Relapse‑free survival (RFS), overall survival (OS) and toxicity were evaluated according to each genotype. Following adjustment for the most relevant clinical variables, excision repair cross‑complimentary group 1 (ERCC1)‑118 and X-ray repair cross-complementing protein 1 (XRCC1‑399) demonstrated significant predictive value for RFS and OS. We also demonstrated that carrying at least one variant XRCC1 Arg399Gln or glutathione S-transferase π 1 (GSTP1) Ile105Val allele significantly increased the risk of any grade 3 or 4 hematological toxicity. In particular, carrying at least one variant GSTP1 Ile105Val allele was also significantly correlated with an increased risk of grade 3 or 4 gastrointestinal toxicity and neurotoxicity. Our data suggested that gastric cancer patients harboring ERCC1‑118 C/C and XRCC1‑399 A/G or A/A genotypes may benefit from receiving OXA‑based adjuvant chemotherapy, and carrying at least one variant XRCC1 Arg399Gln or GSTP1 Ile105Val allele may contribute to the occurrence of adverse drug effects associated with OXA‑based chemotherapy.

Association of XRCC1 gene polymorphisms with the survival and clinicopathological characteristics of gastric cancer

Polymorphisms of the DNA repair gene X-ray repair cross-complementing protein 1 (XRCC1) Arg194Trp, Arg280His, and Arg399Gln have been shown to alter the DNA repair activity and to be associated with genetic susceptibility to several types of cancer. We indentified genotypes of 944 surgically resected gastric cancer (GC) patients by the SNaPshot method to investigate the association of these polymorphisms with clinical progression and outcomes of GC in a Chinese population. The XRCC1 codon 280 His carriers (Arg/His+His/His) held a significantly lower risk of distant metastasis in the dominant model (Pearson chi-square test P=0.019). A weak association of these cases with reduced risk of lymph node metastasis was also found (Pearson chi-square test P=0.051). Individuals carrying at least one Trp allele of XRCC1 codon 194 had an increased risk of death compared with those with Arg/Arg homozygotes in diffuse-type GC (adjusted hazard ratio=1.34, 95% confidence interval=1.05-1.71). Our findings demonstrated that the genetic variant Arg280His in XRCC1 may contribute to cancer progression and that XRCC1 Arg194Trp variants may act as a favorable prognostic indicator of resected GC, particularly among the diffuse-type GC. Larger studies are needed to verify our results in different populations.

Effect of TP53 codon 72 and MDM2 SNP309 polymorphisms on survival of gastric cancer among patients who receiving 5-fluorouracil-based postoperative adjuvant chemotherapy

PURPOSE

Several studies have examined the prognostic value of the TP53 Arg72Pro polymorphism (rs1042522) and/or MDM2 SNP309 (rs2279744) in multiple tumors. Our aim was to determine whether these two genetic variants were correlated with clinical outcome of gastric cancer.

METHODS

We genotyped the two SNPs, TP53 codon 72 polymorphism and MDM2 SNP309, in 940 gastric cancer patients with complete follow-up information and analyzed the correlation between the SNPs and gastric cancer survival.

RESULTS

The two SNPs were not significantly associated with gastric cancer survival. However, the TP53 codon 72 polymorphism had a prominent correlation with clinical outcome of patients receiving 5-fluorouracil (5-Fu)-based postoperative chemotherapy [Arg/Arg + Arg/Pro vs. Pro/Pro, adjusted hazard ratio (HR) = 1.63, 95 % confidence interval (CI) = 1.08-2.44]. Moreover, the unfavorable effect of Arg allele on survival outcome was more predominant for subgroups of older (age >60 years), male, intestinal histology type, advanced stage (T3/T4), and none metastasis of lymph node (N0) or distant (M0) (adjusted HR = 2.34, 95 % CI = 1.24-4.44 for age >60 years; 1.72, 1.10-2.69 for male; 2.30, 1.10-4.80 for intestinal; 1.62, 1.01-2.59 for T3/T4; 3.42, 1.26-9.24 for N0; and 1.62, 1.06-2.47 for M0). Among multiple chemotherapy regimens, the association was only significant in the subgroup of 5-Fu/calcium folinate plus oxaliplatin (FOLFOX) chemotherapy regimen (adjusted HR = 4.47, 95 % CI = 1.21-16.55).

CONCLUSIONS

Our findings showed that TP53 codon 72 polymorphism was associated with survival of gastric cancer patients treated with 5-Fu-based postoperative chemotherapy. The codon 72 polymorphism may be a potential prognostic factor.

Association of CASP7 polymorphisms and survival of patients with non-small cell lung cancer with platinum-based chemotherapy treatment

BACKGROUND

CASP7 plays a crucial role in cancer development and chemotherapy efficacy. We, therefore, explored whether single nucleotide polymorphisms (SNPs) of the CASP7 gene can modulate outcomes of patients with advanced non-small cell lung cancer (NSCLC) treated with first-line platinum-based chemotherapy.

METHODS

We systematically genotyped 17 SNPs of CASP7 first in a discovery set of 279 patients with advanced NSCLC treated with platinum-based chemotherapy and then replicated the results in an independent set of 384 patients, in whom we evaluated associations with overall survival (OS) and progress-free survival (PFS) by Kaplan-Meier analysis and Cox hazards regression analysis.

RESULTS

In both discovery and validation sets as well as in the pooled analysis, heterozygotes of CASP7 rs2227310 and rs4353229 as well as rs12415607 variant allele were strongly associated with a better OS of NSCLC (in the pooled sample: adjusted hazard ratio [HR], 0.73; 95% CI = 0.59-0.90; P = .003; HR, 0.72; 95% CI = 0.59-0.89; P = .002; and HR, 0.76; 95% CI = 0.62-0.94; P = .009; respectively). In stratified analyses of the pooled data set, treated with paclitaxel, individuals carrying variant allele of rs2227310, rs4353229, and rs12415607 had significantly improved OS (HR, 0.60; 95% CI = 0.41-0.87; P = .008; HR, 0.58; 95% CI = 0.39-0.84; P = .004; and HR, 0.61; 95% CI = 0.42-0.89; P = .010; respectively).

CONCLUSIONS

This study provides evidence that genetic variations of CASP7 may modulate OS and PFS of patients with advanced NSCLC treated with platinum-based chemotherapy.

Pro variant of TP53 Arg72Pro contributes to gastric cancer risk in Asians: evidence from a meta-analysis

BACKGROUND

Previous studies investigating the association between TP53 Arg72Pro polymorphism and gastric cancer (GC) risk in Asian population have reported controversial results. Thus, a meta-analysis was performed.

METHODS

A comprehensive literature search was conducted and 17 case-control studies were finally included, involving a total of 5,990 GC cases and 6,812 controls. Subgroup analyses were performed by the sample size.

RESULTS

Meta-analysis of all 17 studies showed variant genotypes of TP53 Arg72Pro to be associated with an elevated GC risk in three genetic comparison models (OR(Pro vs. Arg)=1.13, 95%CI 1.03-1.25, P(OR)=0.01; OR(Homozygote comparison model)=1.33, 95%CI 1.07-1.64, P(OR)=0.009; OR(Dominant genetic model)=1.13, 95%CI 1.05-1.22, P(OR)=0.002). Besides, a more obvious association was observed after the heterogeneity was decreased (all P values less than 0.001). This association was further identified by both subgroup and sensitivity analyses.

CONCLUSIONS

This meta-analysis suggests the Pro variant of TP53 Arg72Pro contributes to gastric cancer risk in Asians.

Polymorphisms in ERCC1, GSTs, TS and MTHFR predict clinical outcomes of gastric cancer patients treated with platinum/5-Fu-based chemotherapy: a systematic review

BACKGROUND

Despite genetic polymorphism in response to platinum/5-Fu chemotherapy in gastric cancer (GC) has been studied, data reported so far are conflicting and critical consideration is needed before translation to the treatment of GC.

METHODS

We performed a meta-analysis by using 20 eligible studies to examine polymorphisms of ERCC1, GSTs, TS and MTHFR in predicting clinical outcomes (response rate, overall survival and toxicity) of GC patients treated with platinum/5-Fu-based chemotherapy. The association was measured using random/fixed effect odds ratios (ORs) or hazard ratios (HRs) combined with their 95% confidence intervals (CIs) according to the studies' heterogeneity. Statistical analysis was performed with the software STATA 9.0 package.

RESULTS

No significant association was found between response rate and genetic polymorphism in TS, MTHFR, ERCC1, GSTM1 and GSTP1. However, response rate was higher in GSTT1 (+) genotype compared with GSTT1 (-) genotype (T-/T+: OR=0.67, 95% CI: 0.47-0.97). With regard to long term outcomes, we could observe a significant longer overall survival in TS 3R/3R [(2R2R+2R3R)/3R3R: HR=1.29, 95% CI: 1.02-1.64] and GSTP1 GG/GA [(GG+AG)/AA: HR=0.51, 95% CI: (0.39, 0.67)] genotypes. In addition, significant association was demonstrated between toxicity and genetic polymorphism in TS, MTHFR and GSTP1 in included studies.

CONCLUSION

Polymorphisms of ERCC1, GSTs, TS and MTHFR were closely associated with clinical outcomes of GC patients treated with platinum/5-Fu-based chemotherapy. Studies with large sample size using the method of multi-variant analyses may help us to give more persuasive data on the putative association in future.

Association between single nucleotide polymorphisms in the XRCC1 and RAD51 genes and clinical radiosensitivity in head and neck cancer

PURPOSE

Individual variability in radiosensitivity is large in cancer patients. Single nucleotide polymorphisms (SNPs) in genes involved in DNA repair and in protection against reactive oxygen species (ROS) could be responsible for such cases of radiosensitivity. We investigated the association between the occurrence of acute reactions in 101 patients with squamous cell carcinoma of the head and neck (SCCHN) after radiotherapy (RT) and five genetic polymorphisms: XRCC1 c.1196A>G, XRCC3 c.722C>T, RAD51 (c.-3429G>C, c.-3392G>T), and GSTP1 c.313A>G.

MATERIALS AND METHODS

Genetic polymorphisms were detected by high resolution melting analysis (HRMA). The development of acute reactions (oral mucositis, skin erythema and dysphagia) associated with genetic polymorphisms was modeled using Cox proportional hazards, accounting for biologically effective dose (BED).

RESULTS

Development of grade ≥2 mucositis was increased in all patients (chemo-radiotherapy and radiotherapy alone) with XRCC1-399Gln allele (HR=1.72). The likelihood of developing grade ≥2 dysphagia was higher in carriers of RAD51 c.-3429 CC/GC genotypes (HR=4.00). The presence of at least one SNP or the co-presence of both SNPs in XRCC1 p.Gln399Arg /RAD51 c.-3429 G>C status were associated to higher likelihood of occurrence of acute toxicities (HR=2.03).

CONCLUSIONS

Our findings showed an association between genetic polymorphisms, XRCC1 c.1196A>G and RAD51 c.-3429 G>C, and the development of radiation-induced toxicities in SCCHN patients.

Part 3: Pharmacogenetic variability in phase II anticancer drug metabolism

Equivalent drug doses may lead to wide interpatient variability in drug response to anticancer therapy. Known determinants that may affect the pharmacological response to a drug are, among others, nongenetic factors, including age, gender, use of comedication, and liver and renal function. Nonetheless, these covariates do not explain all the observed interpatient variability. Differences in genetic constitution among patients have been identified to be important factors that contribute to differences in drug response. Because genetic polymorphism may affect the expression and activity of proteins encoded, it is a key covariate that is responsible for variability in drug metabolism, drug transport, and pharmacodynamic drug effects. We present a series of four reviews about pharmacogenetic variability. This third part in the series of reviews is focused on genetic variability in phase II drug-metabolizing enzymes (glutathione S-transferases, uridine diphosphoglucuronosyl transferases, methyltransferases, sulfotransferases, and N-acetyltransferases) and discusses the effects of genetic polymorphism within the genes encoding these enzymes on anticancer drug therapy outcome. Based on the literature reviewed, opportunities for patient-tailored anticancer therapy are proposed.

CYP2A6 and ERCC1 polymorphisms correlate with efficacy of S-1 plus cisplatin in metastatic gastric cancer patients

Background:

We evaluated the association between polymorphisms of cytochrome P450 2A6 (CYP2A6)/excision repair cross-complementation group 1 (ERCC1)/X-ray repair cross-complementing group 1(XRCC1) and treatment outcomes of metastatic gastric cancer (MGC) patients treated with S-1/cisplatin.

Methods:

Among MGC patients (n=108), who received S-1 (40 mg m⁻² b.i.d., days 1–14) and cisplatin (60 mg m⁻², day 1) every 3 weeks, we analysed the wild-type allele (W) and variants (V) of CYP2A6 (*4, *7, *9, *10), and the polymorphisms of ERCC1 (rs11615, rs3212986) and XRCC1 (rs25487).

Results:

Patients having fewer CYP2A6 variants had better response rates (W/W vs W/V other than *1/*4 vs V/V or *1/*4=66.7 vs 58.3 vs 32.3% P=0.008), time to progression (TTP) (7.2 vs 6.1 vs 3.5 months, P=0.021), and overall survival (23.2 vs 15.4 vs 12.0 months, P=0.004). ERCC1 19442C>A (rs3212986) was also associated with response rate (C/C, 46.7% vs C/A, 55.3% vs A/A, 87.5%) (P=0.048) and TTP (4.4 vs 7.6 vs 7.9 months) (P=0.012). Patients carrying both risk genotypes of CYP2A6 (V/V or 1/*4) and ERCC1 19442C>A (C/C) vs those carrying none showed an adjusted odds ratio of 0.113 (P=0.004) for response, and adjusted hazard ratios of 3.748 (P=0.0001) for TTP and 2.961 (P=0.006) for death.

Conclusion:

Polymorphisms of CYP2A6 and ERCC1 19442C>A correlated with the efficacy of S-1/cisplatin.

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.

Translational medicine and reliability of single-nucleotide polymorphism studies: can we believe in SNP reports or not?

BACKGROUND

The number of genetic association studies is increasing exponentially. Nonetheless, genetic association reports are prone to potential biases which may influence the reported outcome.

AIM

We hypothesized that positive outcome for a determined polymorphism might be over-reported across genetic association studies analysing a small number of polymorphisms, when compared to studies analysing the same polymorphism together with a high number of other polymorphisms.

METHODS

We systematically reviewed published reports on the association of glutathione s-transferase (GST) single-nucleotide polymorphisms (SNPs) and cancer outcome.

RESULT

We identified 79 eligible trials. Most of the studies examined the GSTM1, theGSTP1 Ile105Val mutation, and GSTT1polymorphisms (n = 54, 57 and 46, respectively). Studies analysing one to three polymorphisms (n = 39) were significantly more likely to present positive outcomes, compared to studies examining more than 3 polymorphisms (n=40) p = 0.004; this was particularly evident for studies analysing the GSTM1polymorphism (p =0.001). We found no significant associations between journal impact factor, number of citations, and probability of publishing positive studies or studies with 1-3 polymorphisms examined.

CONCLUSIONS

We propose a new subtype of publication bias in genetic association studies. Positive results for genetic association studies analysing a small number of polymorphisms (n = 1-3) should be evaluated extremely cautiously, because a very large number of such studies are inconclusive and statistically under-powered. Indeed, publication of misleading reports may affect harmfully medical decision-making and use of resources, both in clinical and pharmacological development setting.

Genetic mutations of p53 and k-ras in gastric carcinoma patients from Hunan, China

This case-control study investigated the mutations in p53 and k-ras genes of 123 gastric carcinoma patients and 129 normal individuals from Hunan, China. By isolating genomic DNA from peripheral blood and employing polymerase chain reaction-single strand conformation polymorphism and DNA sequencing, the mutations of p53 exons-5, 6, 7, and 8 and k-ras were detected. The overall mutation frequency of p53 was 29.3%, and mutation was found in all four exons studied. The point mutations were predominant and among them, G:C→A:T was the highest (41.7%), followed by A:T→G:C (25%), G:C→C:G (11.1%), G:C→T:A (8.3%), and A:T→T:A (2.8%). The frameshift mutation was 11.1%. Mutations were detected in codons-131, 132, 133, 135, 149, 151, 162, 167, 173, 174, and 175 of exon 5, codons-193, 197, 213, and 215 of exon 6, codons-245, 246, 248, 249, and 270 of exon 7, and codons-271, 272, 273, and 282 of exon 8 of p53. The overall frequency of mutation in k-ras was 9.8%, mostly in codon-12 (91.7%) and in codon-13 (8.3%). There was no significant relationship between p53 and k-ras gene mutation in gastric carcinoma patients. Also, the relationships between p53 mutation and age, sex, smoking or drinking, and tumor metastasis were not significant. However, the patients with high/high-middle differentiated gastric carcinoma had a higher association with of p53 mutations. This study identified some novel p53 mutations in gastric cancer and showed mutation pattern and frequency of p53 and k-ras in the population of the central southern region of China.

Useful genetic variation databases for oncologists investigating the genetic basis of variable treatment response and survival in cancer

Identification of the genetic basis of variable treatment response, prognosis and survival in cancer patients (i.e. personalized medicine) is an important aim in current medicine. Millions of genetic variations exist in the human genome, some of which are already found to be directly involved in variable treatment response and survival among cancer patients. GENETIC VARIATION DATABASES: Special databases curate, compile, organize and post information related to these genetic variations for the scientific community in a user friendly and free-to-access manner via the World Wide Web. FUTURE DIRECTIONS AND CONCLUSION: Clinicians have a critical role in genetic predictive and prognostic studies. In this review, main public-domain databases on genetic variations, including the two comprehensive genetic variation databases (dbSNP and HapMap), a pharmacogenomics database (PharmGKB), two resequencing-based genetic variation databases (SeattleSNPs and EGP), a population-based genetic variation database (JSNPs), and a copy-number variant database (DGV), and their utility in cancer research are discussed. Utilization of these databases can assist clinicians in their studies related to treatment response and prognosis in cancer patients.

BRCA1 and XRCC1 polymorphisms associated with survival in advanced gastric cancer treated with taxane and cisplatin

This study evaluated the influence of genetic polymorphism influencing drug metabolism on survival in taxane- and cisplatin-treated advanced gastric cancer (AGC). Peripheral blood samples from 207 AGC patients treated with first-line chemotherapy of taxane and cisplatin were used. We investigated polymorphisms that influenced the metabolism of taxane (ATP-binding cassette transporter B1 (ABCB1)), cisplatin (glutathione S-transferase M1 (GSTM1), glutathione S-transferase P1 (GSTP1), glutathione S-transferase T1 (GSTT1), excision repair cross complementing 1 (ERCC1), X-ray Cross Complementing group 3 (XRCC3), X-ray Cross Complementing group 4 (XRCC4), X-ray Cross Complementing group 1 (XRCC1), breast cancer (BRCA1)), and 5-fluorouracil (methylene tetrahydrofolate reductase (MTHFR), thymidylate synthase (TYMS)). A total of 207 patients were enrolled between May 2004 and Dec 2008, and 200 patients were analyzed. The overall response rate was 38.5%. Time to progression and overall survival time were 4.3 +/- 0.19 months and 11.9 +/- 1.05 months, respectively. There was no significant association between genetic polymorphism and response rate. However, the BRCA1 mutant TT homozygote was associated with significant prolongation of overall survival (hazard ratio [HR] = 0.43; 95% confidence interval [CI], 0.20-0.92; P = 0.03) and progression-free survival (HR = 0.51; 95% CI, 0.26-1.00; P = 0.05). Also, the XRCC1 194 CT genotype was associated with inferior overall survival, relative to the XRCC1 194 CC homozygotes (HR = 1.49; 95% CI, 0.11-2.07; P = 0.018).These findings suggest that BRCA1 TT and XRCC1 194 CT genotypes could be modest prognostic markers of AGC response in taxane- and cisplatin-treated patients.

The combination of ERCC1 and XRCC1 gene polymorphisms better predicts clinical outcome to oxaliplatin-based chemotherapy in metastatic colorectal cancer

PURPOSE

To evaluate the effect of excision repair cross-complementing group 1 (ERCC1) and X-ray cross-complementing group 1 (XRCC1) gene polymorphisms on treatment outcome in patients receiving oxaliplatin-based regimens for metastatic colorectal cancer.

METHODS

Hundred and thirteen patients with a diagnosis of metastatic colorectal cancer were treated with oxaliplatin-based chemotherapy. ERCC1 codon 118C/T and XRCC1 codon 399A/G polymorphisms were tested by real-time polymerase chain reaction (RT-PCR) method in peripheral blood lymphocytes of these patients. Disease control rates and survivals were compared by types of genotypes.

RESULTS

Analyses of the patterns of the polymorphism located at ERCC1 codon 118 showed that 55 (48.67%) patients were homozygous for C/C genotype, 15 (13.27%) were homozygous for the T/T genotype, and 43 (38.06%) were heterozygous for C/T genotype. Analyses of the polymorphism located at XRCC1 codon 399 showed that 61 (53.98%) patients were homozygous for A/A genotype, 13 (11.50%) were homozygous for the G/G genotype, and 39 (34.52%) were heterozygous for A/G genotype. After two cycles of chemotherapy, there was complete response (CR) in 1 patient, partial response (PR) in 24 patients, and stable disease (SD) in 56 patients. Altogether in 81 (71.68%) patients the disease was controlled after chemotherapy. Thirty-two (28.32%) patients showed disease progression. After adjusting for some clinical factors, both the ERCC1 polymorphism and the XRCC1 polymorphism lost their roles in predicting DCR (P = 0.662, P = 0.631) and MST (P = 0.692, P = 0.572). But the combination of ERCC1 and XRCC1 polymorphisms was significantly associated with DCR (P = 0.01) and MST (P = 0.000) independently.

CONCLUSIONS

This is the first study which showed that polymorphisms of ERCC1 and XRCC1, in combination not individually, were independent predictors for DCR and OS. This may contribute to the selection of patients who would benefit from oxaliplatin-based chemotherapy for metastatic colorectal cancer.