Determinants of chemosensitivity in gastric cancer (original) (raw)
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International Journal of Colorectal Disease, 2008
Objective Neoadjuvant chemotherapy in gastric cancer is now standard in the Western world; however, only 30-40% of the patients respond to induction therapy. Pretherapeutic predictors of response and prognosis would be of utmost interest to individualize treatment. Glutathione-S-transferase enzymes detoxify therapeutic drugs such as platin derivates and may influence outcome of the treated patients. Therefore, glutathione-S-transferase (GST) polymorphisms were assessed as predictive markers in cisplatinum-based neoadjuvant-treated gastric cancer. Materials and methods DNA was isolated from 139 patients with locally advanced gastric cancer (cT3/4 anyN cM0) before chemotherapy. Multiplex polymerase chain reaction was used for GSTT1 and GSTM1 genes, and allelic discrimination assay with the TaqMan system for the GSTP1 gene. Results One hundred ten patients could be analyzed for GSTT1 (T-:23; T + 87), 112 for GSTM1 (M-:52; M +:60) and 132 for GSTP1 (Ile/Ile: 55; Ile/Val: 59; Val/Val: 18). There was no significant correlation between any of the GSTT1, GSTM1, or GSTP1 genotypes and patients' characteristics or histopathological data; only the GSTM1+ genotype was associated with the non-intestinal subtype of the Lauren classification (p=0.045). GSTT1, GSTM1, and GSTP1 genotypes were not correlated with response to chemotherapy (p=0.57, p=0.38, p=0.33). In R0 resected patients, we found an improved survival for patients with the GSTM1present genotype compared to patients with the GSTM1-null genotype (p=0.017). Moreover, the GSTM1-present genotype showed a significantly better tumor-related (p=0.017) and disease-free survival (p=0.029). Conclusion None of the common GST polymorphisms predicts response in our study, but the GSTM1+ genotype was associated with a better prognosis in completely resected patients. Further investigations on chemotherapyassociated gene polymorphisms are warranted.
Cancer Treatment Reviews, 2009
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.
Journal of the Korean Surgical Society, 2010
The platinum-based modified FOLFOX-6 has been reported as an acceptable chemotherapeutic regimen in treatment of advanced gastric cancer patients. The response rate and drug-induced toxicity of platinum-based chemoagents is different according to several gene polymorphism such as ERCC1, XRCC1 and GSTP1 genes, which were related with therapeutic mechanisms. We aimed to evaluate the effect of gene polymorphism and determine the possibility as prediction factor for responsibility in advanced and recurrent gastric cancer patients treated with modified FOLFOX-6 regimen. Methods: This study was conducted with 55 patients. We sampled 20 ml of peripheral blood to isolate DNA from lymphocytes, and identified genotypes of 3 genes (ERCC1, XRCC1, GSTP1) by PCR-RFL of extracted DNA. Based on medical records, retrospective analysis was made on the patients' clinical characteristics. Results: The overall response rate to modified FOLFOX-6 was 40.0% (22/55). In polymorphism of ERCC1 C8092A, the wild type (CC) showed a statistically significantly lower response rates to chemoagents than the mutant type (CA/AA). In the subtypes of ERCC1 C118T, however, the wild type (CC) showed statistically significantly lower hematological toxicity than the mutant type (CA/AA). But, there was no statistically significance in survival analysis. Conclusion: We suggest that ERCC1 gene polymorphism is clinically more adequate as a feasible factor for predicting the response rate and toxicity of modified FOLFOX-6 regimen in gastric cancer patients.
Expression profiling and long lasting responses to chemotherapy in metastatic gastric cancer
2010
Current palliative chemotherapy (CT) regimens achieve clinical benefits in less than 50% of patients treated for metastatic gastric cancers, and long-term survivals are anecdotical. Genetic polymorphisms and differences at the level of transcription in genes involved in biological processes of drug metabolism, DNA repair and drug resistance can explain the observed individual differences in response to drugs, in survival and in different susceptibility to the toxic effects of CT. The possibility to classify patients on the basis of genetic signatures could help in choosing the CT regimen. We present herein an analysis of genetic and expression profiling of three patients affected by metastatic gastric cancer, treated with CT and alive, disease-free, at 66-82 months. Four patients with typical clinical outcome represented the control group. Expression profiling from paraffin-embedded tumor tissues was performed on an ad hoc set of genes involved in drug metabolism and resistance, DNA repair, cell cycle regulation and growth factors signalling. Genetic polymorphism analysis on DNA extracted from peripheral blood was done by pyrosequencing of genetic markers predictive of drug response. Expression analysis in long-term survivors revealed a significant upregulation of PTEN, TP63, GADD45a and MAPK1 genes. We found also an upregulation of CYP1A1, CYP3A4 and ERBB4 genes. EGF was found to be down-regulated in long-term survivors. ERCC1 C8092A polymorphism seems to be associated with survival in our set of patients. The present study shed light on a set of genes, which could have a predictive role in survival of patients with metastatic gastric tumors.
Pharmacogenetics for individualized cancer chemotherapy
Pharmacology & Therapeutics, 2005
The same doses of medication cause considerable heterogeneity in efficacy and toxicity across human populations. Genetic factors are thought to represent important determinants of drug efficacy and toxicity. Pharmacogenetics focuses on the prediction of the response of tumor and normal tissue to standard therapy by genetic profiling and, thereby, to select the most appropriate medication at optimal doses for each individual patient. In the present review, we discuss the relevance of single nucleotide polymorphisms (SNP) in genes, whose gene products act upstream of the actual drug target sites, that is, drug transporters and drug metabolizing phase I and II enzymes, or downstream of them, that is, apoptosis-regulating genes and chemokines. SNPs in relevant genes, which encode for proteins that interact with anticancer drugs, were also considered, that is, enzymes of DNA biosynthesis and metabolism, DNA repair enzymes, and proteins of the mitotic spindle. A significant body of evidence supports the concept of predicting drug efficacy and toxicity by SNP genotyping. As the efficacy of cancer chemotherapy, as well as the drug-related toxicity in normal tissues is multifactorial in nature, sophisticated approaches such as genome-wide linkage analyses and integrate drug pathway profiling may improve the predictive power compared with genotyping of single genes. The implementation of pharmacogenetics into clinical routine diagnostics including genotype-based recommendations for treatment decisions and risk assessment for practitioners represents a challenge for the future.