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

Germline genetic polymorphisms may influence chemotherapy response and disease outcome in osteosarcoma: a pilot study

BACKGROUND

Osteosarcoma is the most common malignant bone tumor in children and young people. Efficacy of multiagent MAP (methotrexate, doxorubicin [Adriamycin], cisplatin) chemotherapy may be influenced by multiple cellular pathways. This pilot study aimed to investigate the association of 36 candidate genetic polymorphisms in MAP pathway genes with histological response, survival, and grade 3-4 chemotherapy toxicity in osteosarcoma.

METHODS

Blood samples were obtained from 60 patients who had completed MAP chemotherapy. All patients were manually genotyped for 5 polymorphisms. The remaining 31 polymorphisms were genotyped in 50 patients using the Illumina 610-Quad microarray. Associations between candidate polymorphisms and histological response, progression-free survival, and toxicity were estimated using Pearson chi-square and Fisher exact tests, the Kaplan-Meier method, the log-rank test, and the Cox proportional hazards model.

RESULTS

Poor histological response was increased in variants of ABCC2 c.24C>T (P = .011) and GSTP1 c.313A>G p.Ile(105)Val (P = .009), whereas MTHFD1 c.1958G>A p.Arg(653)Gln was protective (P = .03). Methotrexate toxicity was increased in variants of MTHFR c.1298A>C p.Glu(429)Ala (P = .038), ABCB1 c.3435T>C Ile(145)Ile (P = .027), and ABCC2 c.3563T>A p.Val(1188)Glu (P = .028). Variants of GSTP1 c.313A>G p.Ile(105)Val were at increased risk of myelosuppression (P = .024) and cardiac damage (P = .008).

CONCLUSIONS

This pilot study represents the most comprehensive study to date examining the role of genetic polymorphisms in osteosarcoma. Although small and retrospective, it shows that several polymorphisms appear to significantly influence toxicity and clinical outcome. These deserve prospective validation in the hope of optimizing treatment for resistant disease and reducing the late effects burden.

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

BACKGROUND AND AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Part 4: pharmacogenetic variability in anticancer pharmacodynamic drug effects

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

Part 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.

A metabonomic approach to chemosensitivity prediction of cisplatin plus 5-fluorouracil in a human xenograft model of gastric cancer

The prediction of chemosensitivity is a challenging problem in the management of cancer. In the present study, a metabonomic approach was proposed to assess the feasibility of chemosensitivity prediction in a human xenograft model of gastric cancer. BALB/c-nu/nu mice were transplanted with MKN-45 cell line to establish the xenograft model. The mice were then randomized into treatment group (cisplatin and 5-fluorouracil) and control group (0.9% sodium chloride), and their plasma were collected before treatment. Metabolic profiles of all plasma samples were acquired by using high-performance liquid chromatography coupled with a quadrupole time-of-flight mass spectrometer (HPLC/Q-TOF-MS). Based on the data of metabolic profiles and k-Nearest Neighbor algorithm, a prediction model for chemosensitivity was developed and an average accuracy of 90.4% was achieved. In addition, a series of endogenous metabolites, including 1-acyl-lysophosphatidycholines, polyunsaturated fatty acids and their derivatives, were determined as potential indicators of chemosensitivity. In conclusion, our results suggest that the proposed metabonomic approach allows effective chemosensitivity prediction in human xenograft model of gastric cancer. The approach presents a new concept in the chemosensitivtiy prediction of cancer and is expected to be developed as a powerful tool in the personalized cancer therapy.

ERCC1: impact in multimodality treatment of upper gastrointestinal cancer

Platinum-based drugs and radiation are key elements of multimodality treatment in a wide variety of solid tumors and especially tumors of the upper gastrointestinal tract. Cytotoxicity is directly related to their ability to cause DNA damage. This event consecutively triggers the nucleotide excision repair (NER) complex. The NER capacity has a major impact on chemo and radiation sensitivity, emergence of resistance and patient outcome. Excision repair cross-complementing group 1 (ERCC1) is a key molecule in NER. This review provides an overview of the NER complex with a focus on ERCC1. Recent literature has been analyzed and provides information regarding the potential role of ERCC1 as a prognostic factor in multimodality treatment of upper gastrointestinal cancer and cancer risk. To date, the role of ERCC1 as a predictive marker for individual multimodality treatment is far from being firmly established for routine use. However, with reliable methods, established cut-off values and validation in large, prospective, randomized trials, ERCC1 may possibly prove to play an important role as a tumor marker in individualized treatment for upper gastrointestinal cancer.

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.

A phase I/II and pharmacogenomic study of pemetrexed and cisplatin in patients with unresectable, advanced gastric carcinoma

This phase I/II study was conducted to determine the maximum recommended dose of pemetrexed when given in combination with a fixed dose of cisplatin, and the efficacy, toxicity and association of 5,10-methylenetetrahydrofolate reductase (MTHFR) variants with this pemetrexed--cisplatin combination, in patients with unresectable, advanced gastric carcinoma. Patients 18-70 years of age, with stage IV disease or post-surgery recurrence, no earlier palliative chemotherapy, 0 or 1 Eastern Cooperative Oncology Group performance status, were included. The cisplatin dose was 75 mg/m. In phase I, the initial dose of pemetrexed was 600 mg/m, escalated in 100 mg/m increments. In phase II, efficacy, including overall response rate, overall survival, as well as toxicity and MTHFR pharmacogenetics were investigated. Phase I enrolled 16 patients; 700 mg/m was defined as pemetrexed recommended dose. Thirteen serious adverse events were reported; the most common grade 3/4 toxicities were haematologic (10 of 13, 76.9%). Phase II enrolled 73 patients, 69 qualified for safety and 68 for efficacy analysis; 65 for pharmacogenomic analysis. Overall response rate was 23.5% (14.1%, 35.4%), disease control rate 55.9%, median overall survival 11.8 months (95% confidence interval, 7.2-18.5 months), progression-free survival 4.9 months (95% confidence interval, 2.8-7.1 months), and median response duration 5.4 months. Patients with MTHFR A1298C variants had median overall survival of 6.6 months, significantly shorter than patients with the wild type (median 18.5 months, P=0.001). The pemetrexed--cisplatin combination in patients with advanced gastric cancer generates modest efficacy and a manageable toxicity profile. The reduced overall survival in patients with MTHFR A1298C polymorphism variants deserves further investigation.

Folate intake along with genetic polymorphisms in methylenetetrahydrofolate reductase and thymidylate synthase in patients with advanced gastric cancer

BACKGROUND

A relationship between dietary folate intake and efficacy of fluorouracil (FU) is supported by preclinical data. Furthermore, there are several reports that evaluated genetic polymorphisms of MTHFR (methylenetetrahydrofolate reductase) or TYMS (thymidylate synthase) and efficacy of FU. However, to our knowledge, there are no reports that evaluate simultaneously the effects of folate intake and genetic polymorphisms on clinical outcome of gastric cancer patients.

METHODS

We retrospectively analyzed the survival impact of estimated folate intake by a food frequency questionnaire and MTHFR and TYMS polymorphisms in 132 patients with advanced gastric cancer who were treated with first-line FU-based chemotherapy.

RESULTS

Median overall survival was 11.3 months (95% confidence interval, 9.4-13.4 mo) and median progression-free survival was 5.2 months (95% confidence interval, 4.1-6.3 mo). Patients with folate intake of >260 microg/day (n=88) showed longer overall survival compared with low folate intake (n=44; overall survival, 12.2 versus 8.4 mo). In a multivariate Cox model, patients who had folate intake of >260 microg/day, MTHFR 677 TT polymorphism, and TYMS-3' untranslated region 6-bp insertion were associated with better survival. Similar tendency was observed in progression-free survival. No interaction was observed between folate intake and favorable genotypes.

CONCLUSION

Folate intake and genetic polymorphisms of MTHFR and TYMS were associated with better clinical outcome by FU-based chemotherapy in advanced gastric cancer.

IMPACT

Our results suggested folate intake and folate-related genetic polymorphisms may play an important role in efficacy of FU-based chemotherapy in advanced gastric cancer.

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.

Clinical pharmacology and pharmacogenetics in a genomics era: the DMET platform

While no genome-wide pharmacogenetics study has yet been published, the field of pharmacogenetics is moving towards exploratory, large-scale analyses of the interaction between genetic variation and drug treatment. The Drug Metabolizing Enzymes and Transporters (DMET) platform offers a standardized set of 1936 variants in 225 genes related to drug absorption, distribution, metabolism and elimination that is useful to scan the genome for previously unknown associations between variation in absorption, distribution, metabolism and elimination genes and pharmacokinetic and pharmacodynamic outcomes of drug treatment. The purpose of this review is to put the DMET platform into context within the current study designs that have been used in pharmacogenetics, and to explore the role that DMET has played - and will play - in future pharmacogenetics studies.

MTHFR gene polymorphisms and response to chemotherapy in colorectal cancer: a meta-analysis

AIMS

Pharmacogenetic studies investigating the relationship between MTHFR gene polymorphisms and response to fluorouracil-based chemotherapy in patients with colorectal cancer have produced inconclusive results. In an attempt to interpret these results, a meta-analysis of all eligible studies published up until January 2009 was carried out.

MATERIALS & METHODS

A total of ten studies relating MTHFR C677T and six studies relating MTHFR A1298C to the response to chemotherapy in patients with colorectal cancer were included in the meta-analysis and random effects pooled odds ratios were estimated. The heterogeneity between studies, the sources of potential bias and the consistency of genetic effects across ethnicities were explored. Cumulative and recursive cumulative meta-analyses were also performed.

RESULTS

For both the C677T and A1298C polymorphisms, the main analysis revealed nonsignificant heterogeneity and a lack of association under the allele contrast, the recessive and dominant models. The subgroup analysis by ethnicity did not change this pattern of results. The lack of stability of the relative change of odds ratio in the recursive cumulative meta-analysis for both polymorphisms indicated the need for more evidence to support a definite lack of association. There was no differential magnitude of the effect in large versus small studies.

CONCLUSION

The available evidence indicates that MTHFR C677T and A1298C gene polymorphisms cannot be considered as reliable predictors of response to fluorouracil-based chemotherapy in patients with colorectal cancer.

Interaction between glutathione-S-transferase polymorphisms, smoking habit, and HPV infection in cervical cancer risk

PURPOSE

Human papillomavirus (HPV) infection is considered the major cause of cervical cancer (CC), but a number of infected women do not develop invasive lesions, suggesting the role of genetic susceptibility and environmental co-factors for cancer outbreak. The aim of this study was to investigate whether some GST polymorphisms could influence the risk to develop CC, either by themselves or in combination with smoking habit, in a cohort of high-risk HPV (HR-HPV) infected Italian women.

METHODS

The study population comprises 192 Italian women including 81 HR-HPV infected women bearing cervical lesions and 111 healthy controls. The cases include: 26 low-grade squamous intraepithelial lesions (LSILs), 30 high-grade-SIL, and 25 CCs, while controls were all negative for HPV. DNA was extracted from peripheral blood samples or cytobrush and individuals were genotyped for GSTM1, GSTT1, and GSTP1 polymorphisms using PCR and PCR/RFLP techniques.

RESULTS

On studying the association of GSTs gene polymorphisms with cervical cancer lesions, the combination of GSTM1 null, GSTT1 null and GSTP1 AA genotypes, independently on smoking habit, seems to be related to a 5.7-fold increased risk of developing CLs with a considerable statistical significance (P = 0.0091).

CONCLUSIONS

We suggest that the investigation of multiple gene polymorphisms, versus single genes, could contribute to a better understanding of the effect of susceptibility genes on cancer risk.

CyclinD1 and interleukin-1 receptor antagonist polymorphisms are associated with prognosis in neoadjuvant-treated gastric carcinoma

PURPOSE

We evaluated DNA polymorphisms in genes related to DNA repair, cell-cycle control and tumour microenvironment to determine possible associations with response and survival in neoadjuvant-treated gastric cancer patients.

PATIENTS AND METHODS

One hundred and seventy eight patients who received platinum/5FU-based chemotherapy were genotyped for 10 polymorphisms in nine genes (ERCC1: Asn118Asn, C > T; ERCC1: 8092C > A; TP53: Arg72Pro, G < C; cyclinD1: Pro241Pro, G > A; STK15: Phe31Ile, A > T; VEGF: 936C > T; TNF-alpha: -308G > A; interleukin-1b (IL-1B): -511C >T; IL-1 receptor antagonist (IL-1RN): variable tandem repeat; IL-8: -251T>A). Genotypes were correlated with histopathological and clinical response and overall (OS) and progression-free survival (PFS).

RESULTS

Only the cyclinD1 genotypes were associated with clinical response (P(x)(2)=0.044). Significantly worse survival rates were noted in patients homozygous for the G-allele as compared to patients with the AG or AA genotypes of the cyclinD1 polymorphism (OS: P(log-rank) = 0.024; PFS: P(log-rank)=0.007) and in patients homozygous for the short allele compared to all other genotypes at the IL-1RN polymorphic locus (OS: P(log-rank) = 0.026; PFS: P(log-rank) = 0.013). The combination of both unfavourable genotypes demonstrated strong prognostic relevance (OS: P(log-rank) = 0.006; PFS: P(log-rank) = 0.001). Multivariate analysis for OS in the group of completely resected patients (n = 139) revealed statistical significance for ypM (P < 0.001), histopathological response (P < 0.001) and the combined cyclinD1/IL-1RN genotypes (P = 0.043).

CONCLUSION

The cyclinD1 and IL-1RN polymorphisms were associated with survival. The combination of specific cyclinD1 and IL-1RN genotypes showed a particular prognostic relevance and should be considered an independent prognostic marker for neoadjuvant-treated gastric cancer patients.

Pharmacogenetics of fluoropyrimidine and cisplatin. A future application to gastric cancer treatment

Chemotherapy plays an important role in the treatment of gastric cancer both in adjuvant or advanced settings. Recent randomized trials in Japan have proved that S-1, a novel fluoropyrimidine derivative, and cisplatin are the most promising agents. However, both the efficacy and toxicity of a given regimen vary widely among patients due to the inherited variability of genes that involve drug anabolism and catabolism. A narrow therapeutic index of antitumor agents, i.e. a given regimen being too toxic and/or less effective to some segment of patients, prevents the overall improvement of treatment outcomes. Pharmacogenetics, a research field elucidating genetic polymorphism in drug metabolizing enzymes, may contribute to identifying patients who benefit from chemotherapy or who will experience life-threatening toxicity. There are several crucial enzymes identified involving anabolism and the catabolism of fluoropyrimidine and cisplatin, including dihydropyrimidine dehydrogenase, thymidylate synthase, orotate phosphoribosyl transferase, glutathione S transferase, and excision repair cross complementary group. Various polymorphisms and ethnic variabilities of these genes have been elucidated. This review highlights variations within biological functions, detection systems, and possible clinical applications of these enzymatic polymorphisms. This knowledge provides a tool to determine an optimum regimen according to the patient's drug metabolizing characteristics. This stance will contribute to establishing individualized therapies for gastric cancer, which offers superior efficacy with a minimal chance of severe toxicity.

Pharmacokinetics and pharmacogenomics in gastric cancer chemotherapy

Despite extensive efforts, treatment of gastric cancer by chemotherapy, the globally accepted standard, is yet undetermined, and uncertainty remains regarding the optimal regimen. Recent introduction of active "new generation agents" offers hope for improving patient outcomes. Current chemotherapeutic trials provided several regimens that may become a possible standard treatment, including docetaxel/cisplatin/5-FU (TCF) and cisplatin/S-1 for advanced and metastatic cancer and S-1 monotherapy in the adjuvant setting. Along with the development of novel active regimens, individual optimization of cancer chemotherapy has been attempted in order to reduce toxicity and enhance tumor response. Unlike the rare and limited contribution of pharmacokinetic studies, pharmacogenomic studies are increasing the potential to realize the therapeutics against gastric cancer. Despite the limited data, pharmacogenomics in gastric cancer have provided a number of putative biomarkers for the prediction of tumor response to chemotherapies and of toxicity.

Pharmacokinetics and pharmacogenomics in esophageal cancer chemoradiotherapy

Esophageal cancer is one of the most lethal malignancies. Surgical resection of the tumor from the primary site has been the standard treatment, especially for localized squamous cell carcinoma, but considerable clinical efforts during the last decade have resulted in novel courses of treatment. These options include chemoradiotherapy, consisting of a continuous infusion of 5-fluorouracil (5-FU), cisplatin (CDDP), and concurrent radiation. Given the substantial inter- and/or intra-individual variation in clinical outcome, future improvements will likely require the incorporation of a novel anticancer drug, pharmacokinetically guided administration of CDDP or 5-FU, and identification of potential responders by patient genetic profiling prior to treatment. In this review, the latest information on incidence, risk factors, biomarkers, therapeutic strategies, and the pharmacokinetically guided or genotype-guided administration of CDDP and 5-FU is summarized for future individualization of esophageal cancer treatment.

Toward molecularly selected chemotherapy for advanced gastric cancer: state of the art and future perspectives

In the last few years therapeutic options for gastric cancer patients have slowly, but constantly expanded following the introduction of both new chemotherapy agents and innovative indications for treatment. Along with the medical therapy also our knowledge of the molecular mechanisms underlying this disease has progressively improved. However although the available treatment options have undoubtedly increased no clear definitive indications can be made for a standard chemotherapy regimen and we are still unable to accurately select the appropriate treatment for the appropriate patient. Many molecular determinants of response/toxicity to chemotherapy agents have been identified, but only few of them seem to possess the necessary potential for a subsequent application in the clinical practice. Some of these factors have also been indicated as a therapeutic target for a novel class of anti-cancer compounds. This systematic review will analyse available data about these factors with the aim to constitute a starting point for future research.

Pharmacogenetics in chemotherapy of colorectal cancer

Although in recent years, chemotherapeutic options for colorectal carcinoma have expanded, overall response rates are still too low, with high rates of toxicity. Pharmacogenetics aim at predicting both treatment response and adverse effects in individual patients. This review describes the current knowledge of pharmacogenetic markers in the systemic treatment of colorectal cancer. UGT1A1*28 leads to reduced conjugation of SN-38, the active metabolite of irinotecan, resulting in an increased rate of adverse effects, especially neutropenia. To a lesser extent, increased 5-FU toxicity is predicted by DPYD*2A. A variable number of tandem repeats polymorphism in the thymidylate synthase enhancer region, in combination with a single nucleotide polymorphism C>G, may predict poorer response to 5-FU. Efficacy of oxaliplatin is influenced by polymorphisms in components of DNA repair systems, such as ERCC1 and XRCC1. Polymorphic changes in the endothelial growth factor receptor probably predict cetuximab efficacy. Furthermore, the antibody-depended cell-mediated cytotoxic effect of cetuximab may be reduced by polymorphisms in the immunoglobin G fragment C receptors. Bevacizumab efficacy is suspected to be influenced by polymorphisms in the VEGF gene and the hypoxia inducible factor 1alpha gene. Although the interpretation of pharmacogenetic studies is complicated, results imply a promising way of pretreatment prediction of chemotherapy efficacy and toxicity.

Pharmacogenetic analyses of a phase III trial in metastatic gastroesophageal adenocarcinoma with fluorouracil and leucovorin plus either oxaliplatin or cisplatin: a study of the arbeitsgemeinschaft internistische onkologie

PURPOSE

To evaluate the association of germ-line polymorphisms of genes that may impact treatment outcome of platinum and fluorouracil combination chemotherapy in advanced gastric cancer (AGC).

PATIENTS AND METHODS

Blood samples of 156 patients enrolled onto a phase III study comparing fluorouracil, leucovorin, and oxaliplatin with fluorouracil, leucovorin, and cisplatin were collected. Polymorphisms within genes of TS, MTHFR, MTR, OPRT, XPD, ERCC1, XRCC1, XPA, GSTP1, GSTT1, and GSTM1 were genotyped using polymerase chain reaction-based techniques.

RESULTS

Median overall survival (OS) was 11.8 months (95% CI, 9.75 to 13.79 months) and median progression-free survival (PFS) was 5.8 months (95% CI, 4.99 to 6.61 months). The TS-3R/+6 haplotype (P = .004), the GSTT1 deletion polymorphism (P = .015), and genotypes of OPRT-Gly213Ala (P = .003) and XRCC1-Arg399Gln (P = .023) could be identified as independent predictors of OS. For PFS analyses, the TS-3R/+6 haplotye (P = .003) and MTR-A2756G (P = .01) were identified as independent positive predictors. The association between the GSTT1 deletion polymorphism and PFS showed only borderline significance (P = .053). Treatment related hematotoxicity in terms of grade 3/4 leukopenia was lowest among TS-3R/+6 haplotype carriers (P = .037). Grade 3/4 neutropenia was directly associated with the MTR-2756G/G genotype (P = .011), GSTP1-105Ile/Ile genotype (P = .02), and with the ERCC1-118T/8092C-haplotype (P = .042). In addition, significant associations between GSTP1-105Ile/Ile genotype and neurotoxicity and between the XPD-Asn312/751Gln haplotype and nephrotoxicity could be identified (P = .028 and P = .005, respectively).

CONCLUSION

These findings underline the hypothesis that germ-line polymorphisms may play an important role in individualizing chemotherapy in AGC and deserve further prospective evaluation in AGC patients.

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

PURPOSE

The aim of this study was to assess whether genetic polymorphisms in p53, glutathione S-transferase P1 (GSTP1), GSTM1, excision repair cross complementing group 1 (ERCC1) and X-ray repair cross-complementing group 1 (XRCC1) genes are associated with clinical outcome of gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy.

METHODS

The genetic polymorphisms in p53, GSTP1, GSTM1 (null), ERCC1 and XRCC1 were determined in 102 gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy using polymerase chain reaction-ligation detection reaction method.

RESULTS

Among the five studied polymorphisms, p53 codon 72 Pro/Pro, GSTP1 codon 105 Ile/Ile, and XRCC1 codon 399 Gln/Gln + Arg/Gln were associated with poor relapse-free survival and overall survival (P < 0.05); and the prognostic effect was retained in the Cox multivariate analysis. Combination analysis with the three polymorphisms using the Kaplan-Meier method and Cox multivariate analysis revealed that the relapse-free and overall survivals significantly increase with the number of favorable genotypes (P < 0.05). No significant association was found between the GSTM1 (null) or the ERCC1 codon 118 genotypes and the clinical outcome (P > 0.05).

CONCLUSION

Testing for p53 Arg72Pro, GSTP1 Ile105Val, and XRCC1 Arg399Gln polymorphisms may allow identification of gastric cancer patients who will benefit from oxaliplatin-based adjuvant chemotherapy. Selecting specific adjuvant treatments according to the individual genetic background may represent an innovative strategy that warrants prospective studies.

ERCC1 codon 118 C→T polymorphism associated with ERCC1 expression and outcome of FOLFOX-4 treatment in Asian patients with metastatic colorectal carcinoma

We analyzed the influence of codon 118 C→T polymorphism of ERCC1 on its protein expression levels, clinicopathological features, and outcome of 168 Chinese patients with metastatic colorectal carcinoma that had been treated with first-line FOLFOX-4 chemotherapy. A high prevalence of C/C genotype was noted (47.6%, n = 80; 168 patients in total). A marked increase of ERCC1 protein expression levels was also noted in patients with C/T or T/T genotypes (70%vs 20%; P < 0.01), which was associated with significantly lower response to FOLFOX-4 (36.4%vs 57.5%; p = 0.01), and shorter progression-free (7 months vs 13 months; P < 0.01) and overall (16 months vs 25 months; P < 0.01) survival times. By multivariate analysis, this polymorphism was also identified as an independent prognostic factor (P = 0.02). These data suggest that Asian populations have a significantly higher prevalence of the C/C genotype in ERCC1 codon 118, which could be a key determinant for good responses to oxaliplatin-based treatment and favorable outcomes.

Glutathione-S-transferase pi (GSTP1) codon 105 polymorphism is not associated with oxaliplatin efficacy or toxicity in advanced colorectal cancer patients

PURPOSE

Oxaliplatin is detoxified by conjugation to glutathione via the enzyme Glutathione-S-transferase pi (GSTP1). The aim of this study is to investigate the association of GSTP1 Ile105Val genetic polymorphism with oxaliplatin efficacy and toxicity in advanced colorectal cancer (ACC) patients.

EXPERIMENTAL DESIGN

A total of 91 ACC patients received capecitabine and oxaliplatin (CAPOX) as a part of a multicentre phase-III study of the Dutch Colorectal Cancer Group. Tumour response was evaluated according to RECIST, toxicity was graded using CTC, and GSTP1 Ile105Val was determined by pyrosequencing.

RESULTS

Overall survival after CAPOX was similar for patients with the Ile/Ile (11.5 mo), Ile/Val (11.6 mo) and Val/Val (12.6 mo) genotypes (p=0.602). Likewise, there were no statistically significant differences in progression-free survival (p=0.252). Overall grades 3-4 toxicity was not related to genotype (p=0.313). There were no differences in any grade or grades 3-4 neurotoxicity amongst the patients who received > or =500 mg/m(2) of oxaliplatin (p-values of 0.376 and 0.772, respectively).

CONCLUSIONS

The results of this study indicate that the GSTP1 genotype is not predictive for progression-free survival or overall survival in ACC patients treated with CAPOX. Moreover, overall neurotoxicity and neurotoxicity in patients receiving 500 mg/m(2) of oxaliplatin was not associated with GSTP1 genotype.

ERCC1 polymorphism, expression and clinical outcome of oxaliplatin-based adjuvant chemotherapy in gastric cancer

AIM: To determine the influence of excision repair cross complementing group 1 (ERCC1) codon 118 polymorphism and mRNA level on the clinical outcome of gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy.

METHODS: Eighty-nine gastric cancer patients treated with oxalipatin-based adjuvant chemotherapy were included in this study. ERCC1 codon 118 C/T polymorphism was tested by polymerase chain reaction-ligation detection reaction (PCR-LDR) method in peripheral blood lymphocytes of those patients; and the intratumoral ERCC1 mRNA expression was measured using reverse transcription PCR in 62 patients whose tumor tissue specimens were available.

RESULTS: No significant relationship was found between ERCC1 codon 118 polymorphism and ERCC1 mRNA level. The median relapse-free and overall survival period was 20.1 mo and 28.4 mo, respectively. The relapse-free and overall survivals in patients with low levels of ERCC1 mRNA were significantly longer than those in patients with high levels (P < 0.05), while there was no significant association found between ERCC1 118 genotypes and the disease prognosis. Multivariate analysis also showed that ERCC1 mRNA level was a potential predictor for relapse and survival in gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy (P < 0.05).

CONCLUSION: ERCC1 codon 118 polymorphism has no significant impact on ERCC1 mRNA expression, and the intratumoral ERCC1 mRNA level but not codon 118 polymorphism may be a useful predictive parameter for the relapse and survival of gastric cancer patients receiving oxaliplatin-based adjuvant chemotherapy.

The polymorphisms of TS and MTHFR predict survival of gastric cancer patients treated with fluorouracil-based adjuvant chemotherapy in Chinese population

PURPOSE

The aim of this study was to investigate the association of the thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) polymorphisms with the clinical outcomes of gastric cancer patients treated with 5-FU-based adjuvant chemotherapy.

METHODS

One-hundred and sixteen patients with gastric cancer were treated with 5-FU-based adjuvant chemotherapy. The TS (a 28-bp tandem repeat polymorphism in the TS enhancer region (TSER) and a 6 bp deletion/insertion polymorphism in the 3'-untranslated region) and MTHFR C677T polymorphisms were determined in blood samples from those patients using PCR and PCR-LDR (ligation detection reaction) method, respectively.

RESULTS

The overall survival (OS) in patients with the TS ins6/ins6 genotype was significantly shorter than those in patients with the del6/del6 (P = 0.017) and ins6/del6 (P = 0.022) genotype. The relapse-free survival (RFS) and OS in patients with the MTHFR C/C genotype were significantly worse than those in patients with the T/T or C/T genotype (P = 0.043 and 0.040, respectively). Cox multivariate analysis also showed that patients with the TS ins6/ins6 genotype have worse OS than patients with the T/T or C/T genotype (HR = 2.437, P = 0.041), and the MTHFR C/C genotype was associated with shorter RFS (HR = 1.723, P = 0.031) and OS (HR = 1.681, P = 0.056). No significant association was found between the TSER polymorphism and the clinical outcomes (P > 0.05).

CONCLUSION

The polymorphisms of TS 3'-UTR ins6/del6 and MTHFR C677T appear to be potential prognostic factors in gastric cancer patients treated with 5-FU-based adjuvant chemotherapy, which may allow identification of gastric cancer patients who will benefit from 5-FU chemotherapy.

Locally advanced and metastatic gastric cancer: current management and new treatment developments

The management of gastric cancer remains a challenge. In recent years, the most important advances have been achieved in the adjuvant setting for patients with locally advanced disease, where significant survival benefits have been demonstrated for both perioperative chemotherapy and adjuvant chemoradiotherapy. These findings have changed the standard of care for patients with resectable disease. In the setting of metastatic gastric cancer, the development of new cytotoxic regimens must consider the balance between efficacy and toxicity in patients whose overall prognosis is poor. Major advances in recent years include the development of orally administered fluoropyrimidine analogues, which can be used in place of intravenous fluorouracil, and the addition of newer agents such as oxaliplatin and docetaxel, which have demonstrated efficacy in patients with advanced disease. Targeted therapies have had a major impact on the management of certain malignancies, and while their evaluation in the treatment of advanced gastric cancer remains early, it is likely that these agents will continue to be developed and studied in combination with chemotherapy. This article reviews recent advances in the use of chemotherapy for advanced gastric cancer. Targeted therapies, their mechanisms of action and emerging data supporting their use in gastric cancer are also discussed. The two randomized phase III trials supporting adjuvant therapy for locally advanced, resectable gastric cancer are discussed in detail, together with strategies for future trials in this area. Overall, there remains optimism that further incremental gains will be achieved with future studies combining chemotherapy, radiotherapy and targeted therapies, both in the adjuvant and metastatic disease settings.

Effects of Genetic Polymorphisms of Glutathione S-transferase P1 on Helicobacter pylori-associated Gastric Cancer

BACKGROUND/AIMS

Glutathione S-transferase P1 (GSTP1) scavenges radicals via its peroxidase activity. The purpose of this study was to determine the association of GSTP1 genetic polymorphisms with the expression of H. pylori-associated gastroduodenal disease.

METHODS

This study involved 1,911 subjects, comprising patients with four diseases (gastric cancer, dysplasia, benign gastric ulcer, and duodenal ulcer disease) and controls. Biallelic polymorphisms were genotyped by restriction fragment length polymorphism techniques.

RESULTS

The frequency of the genetic polymorphism at nucleotide 313 of GSTP1 did not differ among the five study groups. However, when the gastric cancer group was subdivided into advanced gastric cancer (AGC) and early gastric cancer, the frequency of the G/G genotype was significantly higher in the AGC group than in all the control subgroups (OR: 1.2, 95% CI: 1.1-4.9). The frequency of this genotype differed significantly in the H. pylori-positive AGC group (OR: 2.7, 95% CI: 1.1-6.3) but not in the H. pylori-negative group. Furthermore, the difference was greater in the intestinal type, and was not found in diffuse types of disease.

CONCLUSIONS

This study found that genetic polymorphisms of GSTP1 were associated with H. pylori-associated gastric cancer only during the advanced stage of gastric cancer, with intestinal-type histology evident in H. pylori-positive subjects.

Thymidylate synthase and methylenetetrahydrofolate reductase gene polymorphisms and toxicity to capecitabine in advanced colorectal cancer patients

PURPOSE

To evaluate the effect of thymidylate synthase (TYMS) and methylenetetrahydrofolate reductase (MTHFR) genotypes on toxicity in patients treated with capecitabine for advanced colorectal cancer and to determine the effect of these polymorphisms on the pretreatment levels of serum folate and plasma homocysteine.

EXPERIMENTAL DESIGN

Fifty-four patients with a diagnosis of metastatic colorectal cancer were treated with fixed-dose capecitabine. Germ line DNA from patients was genotyped for TYMS TSER, TSER*3G>C, and 3'-untranslated 6 bp insertion/deletion (3' untranslated region insertion/deletion), and MTHFR c.677C>T and c.1298A>C using PCRs and RFLP. Toxicity was graded by National Cancer Institute Common Toxicity Criteria version 2.0. Response was assessed by Response Evaluation Criteria in Solid Tumors.

RESULTS

MTHFR c.677C>T and c.1298A>C genotypes and diplotypes predicted for grade 2/3 toxicities, whereas the TYMS genotypes had no influence. MTHFR c.677 genotype tended to predict overall survival (P = 0.08). MTHFR c.677 influenced pretreatment homocysteine (P < 0.05) and serum folate levels (P < 0.05). Multivariate analysis suggests that MTHFR c.1298 is an independent predictor of toxicity.

CONCLUSIONS

This study suggests that common genetic variation in MTHFR but not TYMS may be useful for predicting toxicity from capecitabine in patients with advanced colorectal cancer. In addition, MTHFR single nucleotide polymorphisms predicted serum folate and plasma homocysteine levels, and, combined, these factors may be important predictors of capecitabine-induced toxicity.

Modified FOLFOX-6 chemotherapy in advanced gastric cancer: Results of phase II study and comprehensive analysis of polymorphisms as a predictive and prognostic marker

Background

The objective of this study was to evaluate the efficacy and toxicity of infusional 5-fluorouracil (5-FU), folinic acid and oxaliplatin (modified FOLFOX-6) in patients with advanced gastric cancer (AGC), as first-line palliative combination chemotherapy. We also analyzed the predictive or prognostic value of germline polymorphisms of candidate genes associated with 5-FU and oxaliplatin.

Methods

Seventy-three patients were administered a 2 hour infusion of oxaliplatin (100 mg/m²) and folinic acid (100 mg/m²) followed by a 46 hour continuous infusion of 5-FU (2,400 mg/m²). Genomic DNA from the patients' peripheral blood mononuclear cells was extracted. Ten polymorphisms within five genes were investigated including TS, GSTP, ERCC, XPD and XRCC.

Results

The overall response rate (RR) was 43.8%. Median time to progression (TTP) and overall survival (OS) were 6.0 months and 12.6 months, respectively. Toxicities were generally tolerable and manageable. The RR was significantly higher in patients with a 6-bp deletion homozygote (-6 bp/-6 bp) in TS-3'UTR (55.0% vs. 30.3% in +6 bp/+6 bp or +6 bp/-6 bp, p = 0.034), and C/A or A/A in XPD156 (52.0% vs. 26.1% in C/C, p = 0.038). The -6 bp/-6 bp in TS-3'UTR was significantly associated with a prolonged TTP and OS. In a multivariate analysis, the 6-bp deletion in TS-3'UTR was identified as an independent prognostic marker of TTP (hazard ratio = 0.561, p = 0.032).

Conclusion

Modified FOLFOX-6 chemotherapy appears to be active and well tolerated as first line chemotherapy in AGC patients. The 6-bp deletion in TS-3'UTR might be a candidate to select patients who are likely to benefit from 5-FU based modified FOLFOX-6 in future large scale trial.

Vascular endothelial growth factor gene polymorphisms associated with prognosis for patients with colorectal cancer

PURPOSE

Vascular endothelial growth factor (VEGF) or its family may be considered to play an important role in lymphangiogenesis and lymphatic tumor spread, thereby affecting prognosis of colorectal cancer. Accordingly, the present study analyzed VEGF gene polymorphisms and their effect on the prognosis for patients with colorectal cancer.

EXPERIMENTAL DESIGN

Four hundred and forty-five consecutive patients with surgically treated colorectal adenocarcinoma were enrolled in the present study. The genomic DNA was extracted from fresh colorectal tissue and three VEGF (-2578C>A, -634G>C, and +936C>T) gene polymorphisms were determined using a PCR/denaturing high-performance liquid chromatography assay.

RESULTS

Multivariate survival analysis showed that the survival for the patients with the -634 G/C genotype [overall survival (OS): hazard ratio (HR), 0.158; P < 0.001] or C/C genotype (OS: HR, 0.188; P < 0.001) were better than for the patients with the -634G/G genotype, whereas the +936 C/T genotype (OS: HR, 12.809; P < 0.001) or T/T genotype (OS: HR, 37.260; P < 0.001) was associated with a worse survival compared with the +936 C/C genotype. In haplotype analysis, the -2578A/-634G/+936T haplotype exhibited a significantly worse survival when compared with the wild -2578C/-634G/+936C haplotype (OS: HR, 3.866; P < 0.001).

CONCLUSIONS

VEGF gene polymorphisms were found to be an independent prognostic marker for patients with colorectal cancer. Accordingly, the analysis of VEGF gene polymorphisms can help identify patient subgroups at high risk of a poor disease outcome.

Cisplatin plus weekly CPT-11/docetaxel in advanced esophagogastric cancer: a phase I study with pharmacogenetic assessment of XPD, XRCC3 and UGT1A1 polymorphisms

PURPOSE

A multicenter phase I trial to establish the recommended dose of CPT-11/docetaxel plus cisplatin in advanced esophagogastric cancer patients and to correlate the efficacy and toxicity with genetic polymorphisms in DNA repair genes (XPD and XRCC3) and the UGT1A1 gene.

METHODS

Four dose levels with a fixed dose of cisplatin (60 mg/m(2)), day 1, and dose-escalation of CPT-11 (50-70 mg/m(2)) and docetaxel (25-30 mg/m(2)), days 1 and 8, every 3 weeks were planned. Polymorphisms of XPD (Asp312Asn and Lys751Gln), XRCC3 (Thr241Met) and UGT1A1*28 were examined in baseline peripheral blood.

RESULTS

Twenty-eight patients were included at three different dose levels. Dose-limiting toxicities were febrile neutropenia and diarrhea; the recommended dose was established at CPT-11 60 mg/m(2) and docetaxel 25 mg/m(2) plus cisplatin 60 mg/m(2). Objective response was observed in 13 patients (50%). Median time to progression was 6.6 months, and median survival was 11.3 months. Median time to progression was 9.7 months for patients harboring the XRCC3 Met241Met genotype versus 8.4 months for patients with Thr241Met and 3.1 months for those with Thr241Thr (P = .04).

CONCLUSIONS

CPT-11/docetaxel plus cisplatin is active in patients with advanced esophagogastric cancer. XRCC3 Met241Thr polymorphisms could be a useful marker to predict prognosis in patients treated with a cisplatin-based chemotherapy. However, these results are required to be confirmed with a great number of patients.

Impacts of excision repair cross-complementing gene 1 (ERCC1), dihydropyrimidine dehydrogenase, and epidermal growth factor receptor on the outcomes of patients with advanced gastric cancer

Using laser-captured microdissection and a real-time RT-PCR assay, we quantitatively evaluated mRNA levels of the following biomarkers in paraffin-embedded gastric cancer (GC) specimens obtained by surgical resection or biopsy: excision repair cross-complementing gene 1 (ERCC1), dihydropyrimidine dehydrogenase (DPD), methylenetetrahydrofolate reductase (MTHFR), epidermal growth factor receptor (EGFR), and five other biomarkers related to anticancer drug sensitivity. The study group comprised 140 patients who received first-line chemotherapy for advanced GC. All cancer specimens were obtained before chemotherapy. In patients who received first-line S-1 monotherapy (69 patients), low MTHFR expression correlated with a higher response rate (low: 44.9% vs high: 6.3%; P=0.006). In patients given first-line cisplatin-based regimens (combined with S-1 or irinotecan) (43 patients), low ERCC1 correlated with a higher response rate (low: 55.6% vs high: 18.8%; P=0.008). Multivariate survival analysis of all patients demonstrated that high ERCC1 (hazard ratio (HR): 2.38 (95% CI: 1.55-3.67)), high DPD (HR: 2.04 (1.37-3.02)), low EGFR (HR: 0.34 (0.20-0.56)), and an elevated serum alkaline phosphatase level (HR: 1.00 (1.001-1.002)) were significant predictors of poor survival. Our results suggest that these biomarkers are useful predictors of clinical outcomes in patients with advanced GC.

Pharmacogenetics and stomach cancer: an update

Although new drugs and association regimens have been used in recent years, the chemotherapeutic outcome for gastric cancer is still poor and improvement in patient survival is not satisfactory. Pharmacogenetics could represent a useful approach to optimize chemotherapeutic treatments in order to identify individuals that are true candidates for clinical benefits from therapy, avoiding the development of severe side effects. The most recent update regarding gastric cancer pharmacogenetics highlights a prominent role of genetic polymorphisms of thymidylate synthase and glutathione S-transferase in the pharmacological treatment with commonly used drugs, such as 5-fluorouracil and platinum derivatives. In order to validate the genetic markers, further larger scale and controlled studies are required. A future challenge is represented by the introduction of targeted therapy in gastric cancer treatment, with the potential emerging tool of pharmacogenetic impact on this field.

ERCC1 Genotype and Phenotype in Epithelial Ovarian Cancer Identify Patients Likely to Benefit From Paclitaxel Treatment in Addition to Platinum-Based Therapy

Purpose

To investigate the effect of excision repair cross-complementation group 1 (ERCC1) on treatment response and survival of patients treated with platinum chemotherapy with or without paclitaxel.

Patients and Methods

Tumor samples from epithelial ovarian cancer patients were evaluated for ERCC1 mRNA expression and a single nucleotide polymorphism at codon 118 (C>T). Of 178 patients treated with postoperative platinum-based chemotherapy, 75 were also given paclitaxel. For all of these patients, ERCC1 expression and genotype were analyzed for associations with treatment response and survival.

Results

Among the 103 patients treated with platinum without paclitaxel, the C/C genotype, compared with C/T and T/T, was associated with greater risk of disease progression and death (hazard ratio [HR], 1.95, P = .051; HR, 2.01, P = .033, respectively); high levels of ERCC1 mRNA, compared with low levels, were associated with greater risk of disease progression (HR, 2.41; P = .014). Similarly, when the ERCC1 data were combined, patients with the C/C genotype and high ERCC1 expression had greater risk for disease progression (HR, 3.73; P = .003) compared with those with low expression and non-C/C genotype. However, for the 75 patients treated with platinum plus paclitaxel, the C/C genotype and high ERCC1 expression were not associated with poor prognosis, suggesting that paclitaxel may help to alleviate ERCC1-related platinum resistance.

Conclusion

Ovarian cancer patients with high ERCC1 expression or the C/C genotype at codon 118 may benefit from the combination of platinum and paclitaxel, while those with low ERCC1 expression or the C/T or T/T genotype may respond well to platinum without paclitaxel.

Multiplex PCR detection of GSTM1, GSTT1, and GSTP1 gene variants: simultaneously detecting GSTM1 and GSTT1 gene copy number and the allelic status of the GSTP1 Ile105Val genetic variant

The glutathione S-transferase (GST) genes GSTM1, GSTT1, and GSTP1 are involved in the detoxification of a broad range of toxic substances. Genetic polymorphisms in these genes have been studied intensively for their potential role in cancer susceptibility and drug response. In Caucasians, the enzyme activity of GSTM1 and GSTT1 is absent in approximately 50 and 15% of the population, respectively, due to deletions of both chromosomal copies of the genes. A trimodal phenotype pattern exists in which individuals with two, one, or no functional genes are fast, intermediate, or slow "conjugators," respectively. Most studies investigating the effect of the GSTM1 and GSTT1 deletions do not distinguish between fast and intermediate conjugators because the applied genotyping assays only detect if at least one copy of either gene is present. We present a multiplex PCR assay that detects if an individual has none, one, or two copies of the GSTM1 and GSTT1 genes and simultaneously detects the allelic status of the GSTP1 Ile105Val genetic variant. A total of 200 Danes, 100 Somalis, and 100 Greenlanders were genotyped. This multiplex PCR assay enables future large-scale studies to investigate the role of GSTs.

Polymorphism of the DNA repair enzyme XRCC1 is associated with treatment prediction in anthracycline and cyclophosphamide/methotrexate/5-fluorouracil-based chemotherapy of patients with primary invasive breast cancer

OBJECTIVES

Outcome and survival in anthracycline-based and cyclophosphamide/methotrexate/5-fluorouracil-based chemotherapy of invasive breast cancer are unpredictable. Insights into treatment prediction are expected from studies searching for an association between genetic polymorphisms and treatment outcome effects. A common feature of treatment with chemoreagents is therapeutically induced DNA damage. Therefore, we tested the hypothesis of a relationship between event-free survival and genotype distributions of seven polymorphic DNA repair enzymes and four cell cycle regulators.

BASIC METHODS

This case-case comparison included 180 patients with primary invasive breast cancer diagnosed between 1986 and 2000 and subjected to adjuvant chemotherapy (anthracycline/cyclophosphamide or cyclophosphamide/methotrexate/5-fluorouracil). Ninety-two patients were reported without recurrence and 88 were reported with recurrences or dead. Median clinical follow-up was 61.7 months. Constitutional DNA isolated from archived tissues was genotyped at 19 loci by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Statistical analyses included adjusted risk estimates, Kaplan-Meier analyses, Cox proportional hazard model, and permutation testing.

MAIN RESULTS

Carriers of the XRCC1_1196_AA genotype had a reduced risk for recurrence/death (odds ratio adjusted 0.19; 95% confidence interval: 0.06-0.61), which was observed in survival analyses of all patients (P=0.003) and patients treated with chemotherapy but not radiotherapy (P=0.006). Multivariate analysis confirmed XRCC1 as a potential treatment predictor (hazard ratio 0.62; 95% confidence interval: 0.43-0.89). The result was stable upon permutation testing. No other significant associations were observed.

CONCLUSION

The DNA repair enzyme XRCC1 is a potential treatment predictor for the outcome and survival of anthracycline and cyclophosphamide/methotrexate/5-fluorouracil-based chemotherapy of invasive breast cancer.

How do we improve outcomes for gastric cancer?

Although the incidence of gastric cancer is decreasing globally, it remains the second leading cause of cancer death, accounting for 600,000 deaths annually worldwide. It is particularly common in Asia and especially in China, Japan and Korea. In Singapore, it is the fourth commonest cancer in men, who have a 1:50 lifetime risk of developing gastric cancer. Gastric cancer traditionally carries a poor prognosis because of late presentation at an advanced stage of disease. If diagnosed at an early stage, it is a curable disease. Four strategies will systematically help to improve outcomes for gastric cancer: (i) early detection by screening of high-risk groups; (ii) clarification of the hypothesis that Helicobacter pylori eradication in endemic areas with a high incidence of gastric cancer is an effective primary prevention strategy; (iii) improvement of treatment by well-designed clinical trials, coupled with molecular characterization of tumors; and (iv) improving our biological understanding of gastric carcinogenesis.

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.