Prognostic value of tumoral thymidylate synthase and p53 in metastatic colorectal cancer patients receiving fluorouracil-based chemotherapy: phenotypic and genotypic analyses

Hypertension, type 2 diabetes, obesity, and p53 mutations negatively correlate with metastatic colorectal cancer patients' survival

Introduction

We studied the predictive and prognostic influences of hypertension (HT), type 2 diabetes (T2D), weight, and p53 mutations in metastatic colorectal cancer (CRC) patients.

Patients and methods

T2D was diagnosed according to the ADA criteria. HT was classified according to the ACC/AHA guidelines. BMI (body-mass index) was calculated and classified according to the WHO criteria. TruSigt™Oncology 500 kit was applied to construct the genomic libraries for Next Generation Sequencing (NGS) analysis. The Illumina NovaSeq 6000 technological platform and the Illumina TruSight Oncology 500 bioinformatics pipeline were applied to analyze results. Overall survival (OS) was calculated through Kaplan-Meier curves. Univariate and multivariate analyses were performed to assess the relationships between clinical and/or molecular covariates. Associations between HT, T2D, BMI, p53, and clinical variables were evaluated by the χ2 test. P < 0.05 were considered statistically significant.

Results

Two-hundred-forty-four patients were enrolled. One-hundred-twenty (49.2%), 110 (45.1%), and 50 (20.5%) patients were affected by overweight, HT, and T2D, respectively. DC (disease control) was achieved more frequently in patients without T2D (83.1%) compared to the diabetic ones (16.9%) (P = 0.0246). DC, KRAS mutational status, T2D, BMI, and concomitant presence of T2D, BMI, and HT associated with survival (P < 0.05). At multivariate analysis, age (≥65 vs. <65 years), response to first-line chemotherapy (DC vs. no DC), and concomitant presence of T2D, BMI, and HT (HR: 4.56; 95% CI: 2.40-8.67; P = 0.0217) emerged as independent prognostic variables. P53 was mutated in 31/53 analyzed cases (60.4%). The most frequent gene variants were p.Arg175His and p.Cys135Tyr. High BMI (>25 kg/m²) associated with occurrence of p53 mutations (P < 0.0001). P53 mutated patients presented a worse prognosis compared to the wild-type ones (HR: 3.21; 95% CI: 1.43-7.23; P = 0.0047).

Conclusion

Diabetic, hypertensive and overweight metastatic CRC patients are a negative prognostic subgroup deserving specific therapeutic strategies. P53 mutations associate with prognosis and BMI unrevealing complex and unexplored connections between metabolism and cancer occurrence.

MicroRNA-Assisted Hormone Cell Signaling in Colorectal Cancer Resistance

Despite substantial progress in cancer therapy, colorectal cancer (CRC) is still the third leading cause of cancer death worldwide, mainly due to the acquisition of resistance and disease recurrence in patients. Growing evidence indicates that deregulation of hormone signaling pathways and their cross-talk with other signaling cascades inside CRC cells may have an impact on therapy resistance. MicroRNAs (miRNAs) are small conserved non-coding RNAs thatfunction as negative regulators in many gene expression processes. Key studies have identified miRNA alterations in cancer progression and drug resistance. In this review, we provide a comprehensive overview and assessment of miRNAs role in hormone signaling pathways in CRC drug resistance and their potential as future targets for overcoming resistance to treatment.

Pharmacogenomics of 5-fluorouracil in colorectal cancer: review and update

BACKGROUND

Colorectal cancer (CRC) is a disease with high morbidity and mortality rates. 5-fluorouracil (5-FU) is the first-line recommended drug for chemotherapy in patients with CRC, and it has a good effect on a variety of other solid tumors as well. Unfortunately, however, due to the emergence of drug resistance the effectiveness of treatment may be greatly reduced. In the past decade, major progress has been made in the field of 5-FU drug resistance in terms of molecular mechanisms, pre-clinical (animal) models and clinical trials.

CONCLUSIONS

In this article we systematically review and update current knowledge on 5-FU pharmacogenomics related to drug uptake and activation, the expression and activity of target enzymes (DPD, TS and MTHFR) and key signaling pathways in CRC. Furthermore, a summary of drug combination strategies aimed at targeting specific genes and/or pathways to reverse 5-FU resistance is provided. Based on this, we suggest that causal relationships between genes, pathways and drug sensitivity should be systematically considered from a multidimensional perspective. In the design of research methods, emerging technologies such as CRISPR-Cas, TALENS and patient-derived xenograft models should be applied as far as possible to improve the accuracy of clinically relevant results.

5-fluorouracil and other fluoropyrimidines in colorectal cancer: Past, present and future

5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for colorectal cancer (CRC) in the palliative and adjuvant settings. Over the past four decades, several modulation strategies including the implementation of 5-FU-based combination regimens and 5-FU pro-drugs have been developed and tested to increase the anti-tumor activity of 5-FU and to overcome the clinical resistance. Despite the encouraging progress in CRC therapy to date, the patients' response rates to therapy continue to remain low and the patients' benefit from 5-FU-based therapy is frequently compromised by the development of chemoresistance. Inter-individual differences in the treatment response in CRC patients may originate in the unique genetic and epigenetic make-up of each individual. The critical element in the current trend of personalized medicine is the proper comprehension of causes and mechanisms contributing to the low or lack of sensitivity of tumor tissue to 5-FU-based therapy. The identification and validation of predictive biomarkers for existing 5-FU-based and new targeted therapies for CRC treatment will likely improve patients' outcomes in the future. Herein we present a comprehensive review summarizing options of CRC treatment and the mechanisms of 5-FU action at the molecular level, including both anabolic and catabolic ways. The main part of this review comprises the currently known molecular mechanisms underlying the chemoresistance in CRC patients. We also focus on various 5-FU pro-drugs developed to increase the amount of circulating 5-FU and to limit toxicity. Finally, we propose future directions of personalized CRC therapy according to the latest published evidence.

Polymorphisms of MTHFR and TYMS predict capecitabine-induced hand-foot syndrome in patients with metastatic breast cancer

Background

Breast cancer is a global problem, and a large number of new cases are diagnosed every year. Capecitabine is effective in patients with metastatic breast cancer (MBC). Hand-foot syndrome (HFS) is a common adverse effect of capecitabine. In this study, we investigated the association between single nucleotide polymorphisms (SNPs) in genes involved in capecitabine metabolism pathways and capecitabine-induced HFS in Chinese patients with MBC to identify some predictive genetic biomarkers.

Methods

We selected 3 genes involved in capecitabine metabolism and screened genetic variants in these target genes. We genotyped a total of 22 SNPs in the thymidylate synthase gene (TYMS), the methylene tetrahydrofolate reductase gene (MTHFR), and the ribonucleotide reductase M1 gene (RRM1) in 342 MBC patients treated with capecitabine-based chemotherapy. The genotype distributions of each SNP in patients with and without HFS were assessed using Pearson’s χ² test, and the relationship between HFS and genotypes of SNPs was determined using logistic regression analysis. The association between SNPs and their corresponding gene expression was analyzed using the Blood expression quantitative trait loci (eQTL) browser online tools.

Results

We found 4 positive sites for HFS in the TYMS and MTHFR genes: TYMS rs2606241 (P = 0.022), TYMS rs2853741 (P = 0.019), MTHFR rs3737964 (P = 0.029), and MTHFR rs4846048 (P = 0.030). Logistic regression analyses showed that the genotype AG of MTHFR rs3737964 [odds ratio (OR) = 0.54, 95% confidence interval (CI) 0.31–0.97, P = 0.038] and MTHFR rs4846048 (OR = 0.54, 95% CI 0.30–0.98, P = 0.042) were protective factors of HFS, whereas the genotype CT of TYMS rs2853741 (OR = 2.25, 95% CI 1.31–3.87, P = 0.012) increased the risk of HFS. The association between the genotype GT of TYMS rs2606241 (OR = 1.27, 95% CI 0.73–2.23, P = 0.012) and HFS was uncertain. Further eQTL analyses confirmed that the alleles of rs3737964 and rs4846048 affected the gene expression levels of MTHFR in cis.

Conclusions

We have identified four potentially useful pharmacogenetic markers, TYMS rs2606241, TYMS rs2853741, MTHFR rs3737964, and MTHFR rs4846048 to predict capecitabine-induced HFS in MBC patients.

High thymidylate synthase gene expression predicts poor outcome after resection of hepatocellular carcinoma

Introduction

Prognosis after resection of hepatocellular carcinoma (HCC) is highly variable. Compared to clinicopathologic factors, the use of molecular markers to predict outcome has not been well studied. We investigated the prognostic importance of thymidylate synthase (TS) gene expression and polymorphisms in patients after resection of HCC.

Methods

Patients who underwent complete resection of HCC for whom tissue was available were identified. TS gene expression level and polymorphisms were determined in HCC specimens. Prognostic factors were evaluated using Kaplan-Meier curves and Cox proportional hazard models.

Results

The study included 67 patients. In univariate analysis, variables that negatively influenced survival included TNM stage, microvascular invasion, and high TS expression. For the high TS expression group, median survival was 54 months and 5-year actuarial survival was 47%. For the low TS expression group, median survival was not reached and the 5-year actuarial survival was 91%. In multivariate analysis, only high TS expression remained an independent predictor of poor survival (HR = 10.77, 95% CI 1.36–84.91; P = 0.02). TS gene polymorphisms were not associated with TS expression or overall survival.

Conclusions

High TS expression predicts poor outcome after resection of HCC. Molecular markers might be robust predictors of patient outcome after resection of HCC.

Synergistic effect of kaempferol and 5‑fluorouracil on the growth of colorectal cancer cells by regulating the PI3K/Akt signaling pathway

Combination chemotherapy with chemosensitizers can exert synergistic therapeutic effects, reduce toxicity, and delay the induction of drug resistance. In the present study, the antitumor effects were investigated, and the possible underlying mechanisms of kaempferol combined with 5‑fluorouracil (5‑FU) in colorectal cancer cells were explored. HCT‑8 or HCT‑116 cells were treated with various concentrations of kaempferol and/or 5‑FU for the indicated time‑points. An MTT assay was used to determine cell viability, whereas the synergistic effects were assessed by calculating the combination indices of kaempferol and 5‑FU. Annexin V analysis and Hoechst staining were used to determine cell apoptosis. q‑PCR and western blotting were performed to determine the expression levels of Bax, Bcl‑2, thymidylate synthase (TS), PTEN, PI3K, AKT, and p‑AKT. The combination of kaempferol and 5‑FU was determined to be more effective in inhibiting cell viability than either of the agents alone. The inhibition of tumors in response to kaempferol and 5‑FU was associated with the reduction in proliferation ability and stimulation of apoptosis. The protein results indicated that kaempferol and 5‑FU could significantly upregulate the expression levels of Bax and downregulate the expression levels of Bcl‑2 and TS. Furthermore, the combination treatment greatly inhibited the activation of the PI3K/Akt pathway, suggesting the involvement of this pathway in the synergistic effects. The present study demonstrated that kaempferol has a synergistic effect with 5‑FU by inhibiting cell proliferation and inducing apoptosis in colorectal cancer cells via suppression of TS or attenuation of p‑Akt activation. The combination of kaempferol and 5‑FU may be used as an effective therapeutic strategy for colorectal cancer.

Immunohistochemical investigation of prognostic biomarkers in resected colorectal liver metastases: a systematic review and meta-analysis

Background

Many studies have investigated the prognostic role of biomarkers in colorectal liver metastases (CRLM). However, no biomarker has been established in routine clinical practice. The aim of this study was to scrutinize the current literature for biomarkers evaluated by immunohistochemistry as prognostic markers in patients with resected CRLM.

Methods

A systematic review was performed according to the PRISMA guidelines. Articles were identified in the PubMed database with selected search terms and by cross-references search. The REMARK quality criteria were applied. Markers were included if they reported the prognostic impact of immunohistochemical markers in a multivariable setting in relation to overall survival (OS). A meta-analysis was conducted when more than one original article provided survival data of a marker.

Results

In total, 26 biomarkers were identified as independent significant markers for OS in resected CRLM. These biomarkers were found to be involved in multiple oncogenic signalling pathways that control cell growth, apoptosis, angiogenesis and evasion of immune detection. Among these biomarker candidates were Ki-67, EGFR, p53, hTERT, CD34, TSP-1, KISS1, Aurora kinase A and CDX2. CD34 and TSP-1 were reported as significantly associated with survival by more than one study and where therefore pooled in a meta-analysis.

Conclusion

A number of independent prognostic biomarkers for resected CRLM were identified. However, most markers were evaluated in a retrospective setting with small patient cohorts, without external validation. Large, prospective, multicentre studies with standardised methods are needed before biomarkers can translated into the clinic.

Phase 2 study of treatment selection based on tumor thymidylate synthase expression in previously untreated patients with metastatic colorectal cancer: A trial of the ECOG-ACRIN Cancer Research Group (E4203)

BACKGROUND

The authors hypothesized that patients with metastatic colorectal cancer (mCRC) who had tumors with low thymidylate synthase (TS-L) expression would have a higher response rate to combined 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) plus bevacizumab (FOLFOX/Bev) than those with high TS (TS-H) expression and that combined irinotecan and oxaliplatin (IROX) plus bevacizumab (IROX/Bev) would be more effective than FOLFOX/Bev in those with TS-H tumors.

METHODS

TS protein expression was determined in mCRC tissue. Patients who had TS-L tumors received FOLFOX/Bev, and those who had TS-H tumors were randomly assigned to receive either FOLFOX/Bev or IROX/Bev. The primary endpoint was the response rate (complete plus partial responses).

RESULTS

In total, 211 of 247 patients (70% TS-H) were registered to the treatment phase. Efficacy analyses included eligible patients who had started treatment (N = 186). The response rates for patients who received IROX/Bev (TS-H), FOLFOX/Bev (TS-H), and FOLFOX/Bev (TS-L) were 33%, 38%, and 49%, respectively (P = nonsignificant). The median progression-free survival (PFS) was 10 months (95% confidence interval [CI], 9-12 months; 10 months in the IROX/Bev TS-H group, 9 months in the FOLFOX/Bev TS-H group, and 13 months in the FOLFOX/Bev TS-L group). The TS-L group had improved PFS compared with the TS-H group that received FOLFOX/Bev (hazard ratio, 1.6; 95% CI, 1.0%-2.4%; P = .04; Cox regression). The median overall survival (OS) was 22 months (95% CI, 20 29 months; 18 months in the IROX/Bev TS-H group, 21 months in the FOLFOX/Bev TS-H group, and 32 months in the TS-L group). OS comparisons for the 2 TS-H arms and for the FOLFOX/Bev TS-H versus TS-L arms were not significantly different.

CONCLUSIONS

TS expression was prognostic: Patients with TS-L tumors who received FOLFOX/Bev had a longer PFS than those with TS-H tumors, along with a trend toward longer OS. Patients with TS-H tumors did not benefit more from IROX/Bev than from FOLFOX/Bev. Cancer 2018;124:688-97. © 2017 American Cancer Society.

Thymidylate synthase: a predictive biomarker in resected colorectal liver metastases receiving 5-FU treatment

AIM

To investigate the role of thymidylate synthase (TS) as a predictive biomarker in patients with resected colorectal liver metastases (CRLM).

MATERIALS & METHODS

PubMed, EMBASE and Cochrane Library were queried up to June 2017. Meta-analysis was performed using random-effects model. Risk of bias was assessed using funnel plots.

RESULTS

Six eligible studies were included, comprising a total of 542 patients. Meta-analysis demonstrated a trend to reduced overall survival in patients with resected CRLM with TS overexpression, with a hazard ratio of 1.13 (95% CI: 0.99-1.29; p = 0.08). In three studies where patients received systemic fluorouracil, the pooled hazard ratio was 2.25 (95% CI: 1.37-3.71; p = 0.001).

CONCLUSION

TS appears to be a clinically relevant predictive biomarker in patients with resected CRLM receiving systemic 5-FU.

Integrating TYMS, KRAS and BRAF testing in patients with metastatic colorectal cancer

AIM

To investigate the impact of thymidylate synthase (TYMS), KRAS and BRAF in the survival of metastatic colorectal cancer (mCRC) patients treated with chemotherapy.

METHODS

Clinical data were collected retrospectively from records of consecutive patients with mCRC treated with fluoropyrimidine-based chemotherapy from 1/2005 to 1/2007. Formalin-fixed paraffin-embedded tissues were retrieved for analysis. TYMS genotypes were identified with restriction fragment analysis PCR, while KRAS and BRAF mutation status was evaluated using real-time PCR assays. TYMS gene polymorphisms of each of the 3’ untranslated region (UTR) and 5’UTR were classified into three groups according to the probability they have for high, medium and low TYMS expression (and similar levels of risk) based on evidence from previous studies. Univariate and multivariate survival analyses were performed.

RESULTS

The analysis recovered 89 patients with mCRC (46.1% de novo metastatic disease and 53.9% relapsed). Of these, 46 patients (51.7%) had colon cancer and 43 (48.3%) rectal cancer as primary. All patients were treated with fluoropyrimidine-based chemotherapy (5FU or capecitabine) as single-agent or in combination with irinotecan or/and oxaliplatin or/and bevacizumab. With a median follow-up time of 14.8 mo (range 0-119.8), 85 patients (95.5%) experienced disease progression, and 63 deaths (70.8%) were recorded. The 3-year and 5-year OS rate was 25.4% and 7.7% while the 3-year progression-free survival rate was 7.1%. Multivariate analysis of TYMS polymorphisms, KRAS and BRAF with clinicopathological parameters indicated that TYMS 3’UTR polymorphisms are associated with risk for disease progression and death (P < 0.05 and P < 0.03 respectively). When compared to tumors without any del allele (genotypes ins/ins and ins/loss of heterozygosity (LOH) linked with high TYMS expression) tumors with del/del genotype (low expression group) and tumors with ins/del or del/LOH (intermediate expression group) have lower risk for disease progression (HR = 0.432, 95%CI: 0.198-0.946, P < 0.04 and HR = 0.513, 95%CI: 0.287-0.919, P < 0.03 respectively) and death (HR = 0.366, 95%CI: 0.162-0.827, P < 0.02 and HR = 0.559, 95%CI: 0.309-1.113, P < 0.06 respectively). Additionally, KRAS mutation was associated independently with the risk of disease progression (HR = 1.600, 95%CI: 1.011-2.531, P < 0.05). The addition of irinotecan in 1^st line chemotherapy was associated independently with lower risk for disease progression and death (HR = 0.600, 95%CI: 0.372-0.969, P < 0.04 and HR = 0.352, 95%CI: 0.164-0.757, P < 0.01 respectively).

CONCLUSION

The TYMS genotypes ins/ins and ins/LOH associate with worst prognosis in mCRC patients under fluoropyrimidine-based chemotherapy. Large prospective studies are needed for validation of our findings.

Relationship Between Thymidylate Synthase (TS) Genotype and TS Expression: A Tissue Microarray Analysis of Colorectal Cancers

Response of colorectal cancers to 5-fluorouracil appears to be influenced by differences in thymidylate synthase (TS) expression. To explore the relationship between TS 5’ genotype and expression, we analyzed paired tumor and normal tissue from 87 colorectal cancers by tissue microarray. A trend to an association between TS genotype and expression was observed, but the correlation was weak. Although the 2R homozygote was preferentially associated with TS expression (p<0.03), no relationship was observed for the 3R homozygote (p=1.0). The relationship between 5’ TS genotype and TS expression is not simple. For clinical trials incorporating TS status, detection of TS expression in tumors by immunohistochemistry must still remain the benchmark over genotype.

Cancer chemoresistance; biochemical and molecular aspects: a brief overview

The effectiveness of chemotherapy is one of the main challenges in cancer treatment and resistance to classic drugs and traditional treatment processes is an obstacle to this goal. Drug resistance that may be inherent or adventitious can cause poor treatment outcome and tumor relapse. In most cases, resistance to a drug can lead to resistance to many other drugs structure and function of which is not necessarily similar to the first drug. This phenomenon is the main mechanism behind failure of many of metastatic cancers. There are various molecular mechanisms involved in multidrug resistance, including change in the activity of membrane transporters (such as ABC transporters), increase of drug metabolism, change of the target enzyme (such as mutations that change thymidylate synthase and topoisomerases), promotion of DNA damage repair, and escape from drug induced apoptosis. Clinical and laboratory investigations on biomarkers involved in the response to chemotherapy have characterized the key factors behind the failure of treatments. Knowing the molecular factors involved in drug resistance may help us to develop new strategies for more promising chemotherapy and reduce the rate of relapse. In this brief review, molecular mechanisms and tumor microenvironment leading to decreased drug sensitivity, and strategies of reversing drug resistance are described.

Helicobacter pylori infection and a P53 codon 72 single nucleotide polymorphism: a reason for an unexplained Asian enigma

AIM

P53, the most commonly mutated tumor suppressor gene in all types of human cancer, is involved in cell cycle arrest and control of apoptosis. Although p53 contains several polymorphic sites, the codon 72 polymorphism is by far more common. There are divergent reports but many studies suggest p53 pro/pro SNP may be associated with susceptibility to developing various cancers in different regions of the world. The present study aimed to find any correlation between H. pylori infection and progression of carcinogenesis, by studying apoptosis and the p53 gene in gastric biopsies from north Indian population.

MATERIALS AND METHODS

A total of 921 biopsies were collected and tested for prevalence of H. pylori by rapid urease test (RUT), imprint cytology and histology. Apoptosis was studied by the TUNEL method. Analysis of p53 gene polymorphism at codon 72 was accomplished by PCR using restriction enzyme BstU1.

OBSERVATION

Out of 921 samples tested 56.7% (543) were H. pylori positive by the three techniques. The mean apoptotic index (AI) in the normal group was 2.12, while gastritis had the maximum 4.24 followed by gastric ulcer 2.28, gastropathy 2.22 and duodenal ulcer 2.08. Mean AI in cases with gastric cancer (1.72) was less than the normal group. The analysis of p53 72 SNP revealed that p53 (Arg/Arg), (Pro /Arg) variant are higher (40.59% and 33.66%) as compared to p53 pro/pro variant (25.74%) in the healthy population.

CONCLUSIONS

The North Indian population harbors Arg or Pro/Arg SNP that is capable of withstanding stress conditions; this may be the reason of low incidence of gastric disease in spite of high infection with H. pylori. There was no significant association with H. pylori infection and AI. However, there is increased apoptosis in gastritis which may occur independent of H. pylori or p53 polymorphism.

ERCC1 and TS Expression as Prognostic and Predictive Biomarkers in Metastatic Colon Cancer

In patients with metastatic colon cancer, response to first line chemotherapy is a strong predictor of overall survival (OS). Currently, oncologists lack diagnostic tests to determine which chemotherapy regimen offers the greatest chance for response in an individual patient. Here we present the results of gene expression analysis for two genes, ERCC1 and TS, measured with the commercially available ResponseDX: Colon assay (Response Genetics, Los Angeles, CA) in 41 patients with de novo metastatic colon cancer diagnosed between July 2008 and August 2013 at the University of California, San Diego. In addition ERCC1 and TS expression levels as determined by RNAseq and survival data for patients in TCGA were downloaded from the TCGA data portal. We found that patients with low expression of ERCC1 (n = 33) had significantly longer median OS (36.0 vs. 10.1 mo, HR 0.29, 95% CI .095 to .84, log-rank p = 9.0x10^-6) and median time to treatment to failure (TTF) following first line chemotherapy (14.1 vs. 2.4 mo, HR 0.17, 95% CI 0.048 to 0.58, log-rank p = 5.3x10^-4) relative to those with high expression (n = 4). After accounting for the covariates age, sex, tumor grade and ECOG performance status in a Cox proportional hazard model the association of low ERCC1 with longer OS (HR 0.18, 95% CI 0.14 to 0.26, p = 0.0448) and TTF (HR 0.16, 95% CI 0.14 to 0.21, p = 0.0053) remained significant. Patients with low TS expression (n = 29) had significantly longer median OS (36.0 vs. 14.8 mo, HR 0.25, 95% CI 0.074 to 0.82, log-rank p = 0.022) relative to those with high expression (n = 12). The combined low expression of ERCC1/TS was predictive of response in patients treated with FOLFOX (40% vs. 91%, RR 2.3, Fisher’s exact test p = 0.03, n = 27), but not with FOLFIRI (71% vs. 71%, RR 1.0, Fisher’s exact test p = 1, n = 14). Overall, these findings suggest that measurement of ERCC1 and TS expression has potential clinical utility in managing patients with metastatic colorectal cancer.

Prognostic implications of thymidylate synthase gene polymorphisms in patients with advanced small bowel adenocarcinoma treated with first-line fluoropyrimidine-based chemotherapy

Thymidylate synthase (TS) gene polymorphisms such as tandem repeat (TR) polymorphisms and single-nucleotide polymorphisms (SNPs) affect transcriptional efficiency of the TS gene and may be prognostic markers for fluoropyrimidine-based therapy in various gastrointestinal cancers. However, data for TS polymorphisms on clinical outcomes in advanced small bowel adenocarcinoma (SBA) are limited. We retrospectively enrolled 58 locally advanced/metastatic SBA patients treated with first-line fluoropyrimidine-based chemotherapy and analyzed the relationship between TS genotypes and clinical outcomes in 30 patients who were available for tumor tissue. Based on TR polymorphisms and a G>C SNP in the promoter region of the TS gene, 74% of patients had high TS expression genotypes (2R/3RG, 3RG/3RC, 3RG/3RG); the remainder had low TS expression genotypes (2R/2R, 2R/3RC, 3RC/3RC). After a median follow-up of 48.8 months, median progression-free survival (PFS) and overall survival (OS) in all patients were 6.0 and 11.3 months, respectively. However, patients with low TS expression genotypes had better median PFS (12.8 vs. 4.3 months, P=0.027) and OS (28.8 vs. 8.9 months, P=0.025) than those with high TS expression genotypes. In multivariate analysis, poor Eastern Cooperative Oncology Group performance status [hazard ratio (HR), 2.85; 95% CI, 1.02-7.93] and high TS expression genotypes (HR, 3.49; 95% CI, 1.13-10.78) were independent prognostic factors for worse OS. Therefore, TS genotypes, based on a G>C SNP in the TR sequence of the TS gene, may be a useful biomarker for predicting outcomes for fluoropyrimidine-based chemotherapy in patients with locally advanced/metastatic SBA.

Thymidylate synthase genetic polymorphism and plasma total homocysteine level in a group of Turkish patients with rheumatoid arthritis: relationship with disease activity and methotrexate toxicity

BACKGROUND

The polymorphism of thymidylate synthase (TS) gene and homocysteine are reported to have a relationship to methotrexate (MTX) metabolism, with conflicting results. The aim of this study was to determine homocysteine levels and the frequency of TS gene triple repeat (TS3R) and double repeat (TS2R) polymorphisms in a group of Turkish RA patients and evaluate its association with MTX toxicity and disease activity.

METHODS

Sixty-four patients with RA and 31 control subjects with a mean age of 48.7 ± 12.5 and 46.2 ± 13.4 years, were enrolled to the study. Demographic characteristics were obtained and number of patients with MTX-related adverse affects, were recorded in the patient group. The homocysteine levels and TS2R/TS3R polymorphisms of the TS gene were analyzed and the distribution of genotypes according to MTX toxicity and disease activity, were determined.

RESULTS

The demographic properties were similar between the patient and control subjects. Folic acid supplementation with a mean dose of 5mg folic acid/week, was present in all patients. Thirty-six of the 64 patients showed adverse effects to MTX treatment. The frequency of TS2R and TS3R polymorphisms were found to be similar in the patient and control groups. TS2R and TS3R gene polymorphisms were found to be similar in patients with and without MTX-related adverse events. The mean homocysteine level was also similar in patients with and without TS gene polymorphism, but was found to be higher (12.45μmol/L vs 10.7μmol/L) in patients with MTX-related side effects than in patients without side effects. The mean level of homocysteine was correlated with levels of ESR in the patient group.

CONCLUSIONS

In conclusion, homocysteine levels might effect the disease activity and toxicity of MTX but 2R and 3R polymorphisms in the TS gene, were not related with MTX-related toxicity in RA patients receiving folate supplementation. Further studies are needed to illuminate the polymorphisms in other enzymes that might be responsible from the MTX toxicity in patients suffering from RA.

Distinct gene expression profiles of proximal and distal colorectal cancer: implications for cytotoxic and targeted therapy

Colorectal cancer (CRC) is a heterogeneous disease with genetic profiles and clinical outcomes dependent on the anatomic location of the primary tumor. How location impacts the molecular makeup of a tumor and how prognostic and predictive biomarkers differ between proximal versus distal colon cancers is not well established. We investigated the associations between tumor location, KRAS and BRAF mutation status, and the mRNA expression of proteins involved in major signaling pathways, including tumor growth (EGFR), angiogenesis (VEGFR2), DNA repair (ERCC1) and fluoropyrimidine metabolism (TS). FFPE tumor specimens from 431 advanced CRC patients were analyzed. The presence of 7 different KRAS base substitutions and the BRAF V600E mutation was determined. ERCC1, TS, EGFR and VEGFR2 mRNA expression levels were detected by RT-PCR. BRAF mutations were significantly more common in the proximal colon (p<0.001), whereas KRAS mutations occurred at similar frequencies throughout the colorectum. Rectal cancers had significantly higher ERCC1 and VEGFR2 mRNA levels compared to distal and proximal colon tumors (p=0.001), and increased TS levels compared to distal colon cancers (p=0.02). Mutant KRAS status was associated with lower ERCC1, TS, EGFR, and VEGFR2 gene expression in multivariate analysis. In a subgroup analysis, this association remained significant for all genes in the proximal colon and for VEGFR2 expression in rectal cancers. The mRNA expression patterns of predictive and prognostic biomarkers as well as associations with KRAS and BRAF mutation status depend on primary tumor location. Prospective studies are warranted to confirm these findings and determine the underlying mechanisms.

miR-203 enhances chemosensitivity to 5-fluorouracil by targeting thymidylate synthase in colorectal cancer

MicroRNAs (miRNAs) are a conserved class of small non-coding RNAs that play important roles in diverse biological processes, including chemoresistance. However, the molecular mechanism as to how miR-203 modulates the chemosensitivity to 5-fluorouracil (5-FU) in colorectal cancer is poorly known. In the present study, we found that miR-203 was downregulated in the 5-FU-resistant cell line LoVo/5-Fu, and was inversely correlated with the extent of 5-FU chemoresistance. Cytotoxicity assay showed that the inhibition of miR-203 expression enhanced 5-FU chemoresistance in colorectal cancer cells, while miR-203 overexpression increased 5-FU chemosensitivity. We then validated that thymidylate synthase (TYMS) was a direct target of miR-203 and miR-203 suppressed TYMS protein levels. Silencing of TYMS enhanced 5-FU chemosensitivity, similar to the roles of miR-203. Finally, we discovered that miR-203 increased the inhibitory effects of 5-FU on tumor growth in vivo. Overall, our data indicate that miR-203 enhances 5-FU chemosensitivity via the downregulation of TYMS in colorectal cancer and provide important insight into the mechanism of 5-FU resistance in colorectal cancer patients. More important, the present study suggests that miR-203 has the potential as a therapeutic strategy for 5-FU-resistant colorectal cancer.

Molecular patterns in deficient mismatch repair colorectal tumours: results from a French prospective multicentric biological and genetic study

Background:

To test the prognostic value of tumour protein and genetic markers in colorectal cancer (CRC) and examine whether deficient mismatch repair (dMMR) tumours had a distinct profile relative to proficient mismatch repair (pMMR) tumours.

Methods:

This prospective multicentric study involved 251 stage I–III CRC patients. Analysed biomarkers were EGFR (binding assay), VEGFA, thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) expressions, MMR status, mutations of KRAS (codons 12–13), BRAF (V600E), PIK3CA (exons 9 and 20), APC (exon 15) and P53 (exons 4–9), CpG island methylation phenotype status, ploidy, S-phase, LOH.

Results:

The only significant predictor of relapse-free survival (RFS) was tumour staging. Analyses restricted to stage III showed a trend towards a shorter RFS in KRAS-mutated (P=0.005), BRAF wt (P=0.009) and pMMR tumours (P=0.036). Deficient mismatch repair tumours significantly demonstrated higher TS (median 3.1 vs 1.4) and TP (median 5.8 vs 3.5) expression relative to pMMR (P<0.001) and show higher DPD expression (median 14.9 vs 7.9, P=0.027) and EGFR content (median 69 vs 38, P=0.037) relative to pMMR.

Conclusions:

Present data suggesting that both TS and DPD are overexpressed in dMMR tumours as compared with pMMR tumours provide a strong rationale that may explain the resistance of dMMR tumours to 5FU-based therapy.

Can we improve the clinical risk score? The prognostic value of p53, Ki-67 and thymidylate synthase in patients undergoing radical resection of colorectal liver metastases

OBJECTIVES

The aim of this study was to assess whether biological markers can provide prognostic information additional to that supplied by the clinical risk score (CRS) in patients with colorectal liver metastases.

METHODS

A retrospective review of a prospectively maintained database was conducted. Patients selected for this study were treated between 1996 and 2011 with potentially curative liver surgery. Expressions of p53, Ki-67 and thymidylate synthase were assayed using immunohistochemical techniques on tissue microarrays.

RESULTS

A total of 98 (24%) of 406 patients met the inclusion criteria. The median follow-up was 103 months. Analysis revealed a correlation between p53 protein overexpression and high CRS (P = 0.058). Following multivariate analysis, only high CRS remained as an independent negative prognostic predictor of survival (P = 0.018), as well as an indicator of early recurrence of disease (P = 0.010). Of the biological markers investigated, only Ki-67 overexpression was identified as a positive predictor of survival on multivariate analysis (P = 0.038).

CONCLUSIONS

Ki-67 overexpression was a positive predictor of survival. Only high CRS remained an independent negative prognostic predictor.

Thymidylate synthase polymorphisms are associated to therapeutic outcome of advanced non-small cell lung cancer patients treated with platinum-based chemotherapy

Thymidylate synthase (TYMS) has three polymorphisms that may modulate thymidylate synthase (TS) expression levels: (1) 28 base pairs (bp) variable number tandem repeat (VNTR) (rs34743033); (2) single nucleotide polymorphism (SNP) C>G at the twelfth nucleotide of the second repeat of 3R allele (rs2853542); and (3) 6 bp sequence deletion (1494del6, rs34489327). This study was conducted to evaluate the influence of TYMS polymorphisms on the survival of Portuguese patients with advanced non-small cell lung cancer (NSCLC) undergoing platinum-based chemotherapy. Our results showed no statistically significant differences between VNTR genotypes; although, considering the SNP C>G, homozygotes 3RG presented a better prognostic at 36 months (p=0.004) and overall survival (p=0.003) when compared to 2R3RG patients. Patients with "median/high expression genotypes" demonstrated a better survival at 12 months (p=0.041) when compared to "low expression genotypes". Furthermore, 6 bp- carriers (p=0.006) showed a better survival at 12 months when compared to 6 bp+ homozygotes patients. When analyzing TYMS haplotypes, better survival at 12 months was observed for patients carrying haplotypes with the 6 bp- allele (2R6 bp-; p=0.026 and 3RG6 bp-; p=0.045). This is the first report that evaluates the three major TYMS polymorphisms in the therapeutic outcome of NSCLC in Portugal. According to our results, the TYMS polymorphisms may be useful tools to predict which advanced NSCLC patients could benefit more from platinum-based chemotherapy regimens.

Tissue-based biomarkers predicting outcomes in metastatic colorectal cancer: a review

Although there have been recent advances in the treatment of metastatic colorectal cancer, particularly with systemic chemotherapy, new biological agents and surgical metastasectomy, the disease remains difficult to treat. To personalise the management of mCRC and optimise patient outcomes, it is vital to acquire a deeper understanding of its natural history and mechanisms behind disease progression. This may be achieved by extensive study of tumour biomarkers: proteins or genetic alterations within neoplastic cells or their surrounding stroma that may be used to predict patient outcomes, disease trajectory and response to various therapies. The discovery of mutant Kirsten-RAS in determining patients who may be refractory to anti-epidermal growth factor receptor treatments has reinvigorated and reiterated the importance of our attempts to individualise cancer care. While many biomarkers have been studied and shown promise in the setting of mCRC, they are, with the exception of K-ras testing not used currently in a clinical setting due to conflicting results, small patient samples and methodological variations. Larger, multi-centric studies with uniform methods of tumour marker study are required to effectively tailor systemic therapies and select appropriate candidates for surgical metastasectomy.

Genetic variant rs16430 6bp > 0bp at the microRNA-binding site in TYMS and risk of sporadic breast cancer risk in non-Hispanic white women aged ≤ 55 years

Thymidylate synthase (TYMS) is involved in the folate metabolism and provision of nucleotides needed for DNA synthesis and repair. Thus, functional genetic variants in TYMS may alter cancer risk. In the study, we evaluated associations of three germline variants (rs2790 A > G, rs16430 6 bp > 0 bp, and rs1059394 C > T) in the predicted miRNA-binding sites of TYMS with risk of sporadic breast cancer in non-Hispanic white women aged ≤ 55. We found that carriers of the rs16430 0 bp variant allele had an increased risk of breast cancer [adjusted odd ratio (OR) = 1.37, 95% confidence interval (CI): 1.08-1.73; P = 0.010], compared with carriers of the 6 bp/6 bp genotype. This increased risk was more evident in older subjects (OR = 1.47, 95% CI = 1.06-2.03, P = 0.022), never smokers (OR = 1.67, 95% CI = 1.23-2.25, P < 0.001), never drinkers (OR = 1.44, 95% CI = 1.01-2.05, P = 0.043), and estrogen receptor-positive patients (OR = 1.46, 95% CI = 1.11-1.92, P = 0.006), regardless of tumor stages. The results are consistent with the functional analyses of rs16430 as previously reported, which showed that the 0 bp allele had a decrease in both luciferase activity by ∼ 70% and mRNA levels by ∼ 50% compared with the 6bp allele. Additionally, the rs16430 variant was predicted to influence the binding activity of miR-561. Taken together, these findings indicate that the TYMS rs16430 may contribute to the etiology of sporadic breast cancer in non-Hispanic white women aged ≤ 55 yr. Further validation in large population-based or cohort studies is needed.

Thymidylate synthase gene polymorphism and survival of colorectal cancer patients receiving adjuvant 5-fluorouracil

Limited studies indicate a possible association of 5'-UTR thymidylate synthase enhancer region polymorphism and treatment outcome in patients medicated with 5-fluorouracil (5-FU). The study was designed to verify the relationship in patients with colorectal cancer (CRC), a Polish population that received 5-FU-based adjuvant chemotherapy. The study analyzed 145 Astler-Coller B2 and C CRC patients. Genotyping for a variable number of tandem repeats and G to C single-nucleotide polymorphism in the 5'-UTR of the thymidylate synthase (TS) gene was carried out. TS genotypes were classified into high expression (high TS) and low expression types (low TS). High TS was found in 22.8% of patients. The right-side tumors were more frequently associated with high TS than the left-side tumors (p=0.024). High TS was only found in 9.3% of rectal tumors, but in 29.7% of colon cancers (p=0.0042). Disease-free survival after 20 months (DFS 20) was longer in subjects with low TS than in high TS (p=0.043). Patients who underwent chemotherapy had longer DFS 20 in the low TS than in the high TS subgroup (p=0.051). The low TS was found to be an independent good prognostic factor for DFS 20 in the whole group as well as in the subgroup treated with chemotherapy (p=0.024 and p=0.034, respectively). Patients with low TS did not show any differences in DFS 20 whether they were treated with adjuvant chemotherapy or not. Proximal CRC tumors are characterized by higher TS expression genotypes than distal tumors, and are at significantly greater risk of early recurrence during the first 20 months after surgery.

Predicting chemotherapeutic response and toxicity in colorectal cancer

SUMMARY While treatment for colorectal cancer has evolved significantly over the past 10 years with the introduction of active chemotherapeutic agents and targeted therapies, this has been at the cost of increased toxicity for patients; and significant financial burden for governments and patients. Predicting clinical outcomes, especially given the largely elderly patient population involved, is therefore paramount. This review seeks to summarize existing data regarding the prediction of response and toxicity to chemotherapy agents currently used in the treatment of colorectal cancer.

Influence of pharmacogenomic profiling prior to pharmaceutical treatment in metastatic colorectal cancer on cost effectiveness : a systematic review

BACKGROUND

Metastatic colorectal cancer (mCRC) imposes a substantial health burden on individual patients and society. Furthermore, rising costs in oncology cause a growing concern about reimbursement for innovations in this sector. The promise of pharmacogenomic profiling and related stratified therapies in mCRC is to improve treatment efficacy and potentially save costs. Among other examples, the commonly used epidermal growth factor receptor (EGFR) antibodies cetuximab and panitumumab are only effective in patients with kirsten rat sarcoma viral oncogene homolog (KRAS) wild-type cancers. Hence, the adaptation of predictive biomarker testing might be a valid strategy for healthcare systems worldwide.

OBJECTIVE

This study aims to review the clinical and economic evidence supporting pharmacogenomic profiling prior to the administration of pharmaceutical treatment in mCRC. Moreover, key drivers and areas of uncertainty in cost-effectiveness evaluations are analysed.

METHODS

A systematic literature review was conducted to identify studies evaluating the cost effectiveness of predictive biomarkers and the result dependent usage of pharmaceutical agents in mCRC.

RESULTS

The application of predictive biomarkers to detect KRAS mutations prior to the administration of EGFR antibodies saved treatment costs and was cost effective in all identified evaluations. However, because of the lack of data regarding cost-effectiveness analyses for predictive biomarker testing, e.g. for first-line treatment, definitive conclusions cannot be stated. Key drivers and areas of uncertainty in current cost-effectiveness analyses are, among others, the consideration of predictive biomarker costs, the characteristics of single predictive biomarkers and the availability of clinical data for the respective pharmaceutical intervention. Especially the cost effectiveness of uridine diphosphate-glucuronyl transferase 1A1 (UGT1A1) mutation analysis prior to irinotecan-based chemotherapy remains unclear.

CONCLUSION

Pharmacogenomic profiling has the potential to improve the cost effectiveness of pharmaceutical treatment in mCRC. Hence, quantification of the economic impact of stratified medicine as well as cost-effectiveness analyses of pharmacogenomic profiling are becoming more important. Nevertheless, the methods applied in cost-effectiveness evaluations for the usage of predictive biomarkers for patient selection as well as the level of evidence required to determine clinical effectiveness are areas for further research. However, mCRC is one of the first indications in which stratified therapies are used in clinical practice. Thus, clinical and economic experiences could be helpful when adopting pharmacogenomic profiling into clinical practice for other indications.

Updated meta-analysis of the TP53 Arg72Pro polymorphism and gastric cancer risk

OBJECTIVE

The p53 tumor suppressor pathway plays an important role in gastric cancer (GC) development. Auto-regulatory feedback control of p53 expression is critical to maintaining proper tumor suppressor function. So far, several studies between p53 Arg72Pro polymorphism and GC have generated controversial and inconclusive results.

METHODS

To better assess the purported relationship, we performed a meta-analysis of 19 publications. Eligible studies were identified by searching the Pubmed database. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess any link.

RESULTS

Overall, a significant association was detected between the p53 Arg72Pro polymorphism and GC risk (Pro-allele vs. Arg-allele: OR=1.05, 95%CI=1.01-1.08; Pro/Pro vs. Arg/Arg: OR=1.13, 95%CI=1.04-1.22). Moreover, on stratified analysis by race, significantly increased risk was found for Asian populations (Pro-allele vs. Arg-allele: OR=1.06, 95%CI=1.02-1.10; Pro/Pro vs. Arg/Arg: OR=1.16, 95%CI=1.07-1.26; Pro/Pro+Pro/Arg vs. Arg/Arg: OR=1.58, 95%CI=1.09-2.27).

CONCLUSIONS

Our study provided evidence that the p53 72Pro allele may increase GC risk in Asians. Future studies with larger sample size are warranted to further confirm this association in more detail.

Management of colorectal cancer patients after resection of liver metastases: can we offer a tailored treatment?

Surgical resection remains the only option of cure for patients with colorectal liver metastases, and no patient should be precluded from surgery. There is much controversy not only regarding the most appropriate therapeutic approach in the neoadjuvant setting but also after surgery is performed. Many patients will experience early relapses but others will be long survivors. We need to establish reliable prognostic and predictive factors to offer a tailored treatment. Several prognostic factors after metastasectomy have been identified: high C-reactive protein levels, a high neutrophil-lymphocyte ratio, elevated neutrophil count and low serum albumin are related to a worst outcome. Elevated CEA and Ki 67 levels, intrahepatic and perihepatic lymph node invasion are also some of the markers related to a worst outcome. In contrast, the administration of preoperative chemotherapy has been associated with a better prognosis after hepatectomy. The administration of adjuvant chemotherapy should be done taking in consideration these factors. Regarding predictive factors, determination of ERCC1, TS, TP and DPD and UGT1 polymorphisms assessment could be considered prior to chemotherapy administration. This would avoid treatment related toxicities and increase this population quality of life.

Can population differences in chemotherapy outcomes be inferred from differences in pharmacogenetic frequencies?

Inter-ethnic differences in drug handling and frequencies of pharmacogenetic variants are increasingly being characterized. In this study, we systematically assessed the feasibility of inferring ethnic trends in chemotherapy outcomes from inter-ethnic differences in pharmacogenetic variant frequencies. Frequencies of 51 variants and chemotherapy outcomes of East Asian and Caucasian colorectal cancer patients on standard chemotherapy regimens were summarized by meta-analyses, and variant frequencies were validated by MassARRAY analysis. Inferences of relative chemotherapy outcomes were made by considering minor allele function and population differences in their frequency. Significant population differences in genotype distributions were observed for 13/23 (60%) and 27/35 (77%) variants in the meta-analyses and validation series, respectively. Across chemotherapy regimens, East Asians had lower rates of grade 3/4 toxicity for diarrhea and stomatitis/mucositis than Caucasians, which was correctly inferred from 13/18 (72%, P=0.018) informative genetic variants. With appropriate variant selection, inferring relative population toxicity rates from population genotype differences may be relevant.

Associations of polymorphisms of folate cycle enzymes and risk of breast cancer in a Brazilian population are age dependent

Polymorphisms in genes involved in folate metabolism have been shown to be implicated in breast cancer risk but with contradictory results. In this case-control study, we investigated the association between MTHFR C677T and A1298C, TYMS 5'-UTR, MTR A2756G and cSHMT C1420T and also the folate carrier (RFC1 G80A) and breast cancer risk in a northeastern Brazilian population. The study included 183 women diagnosed with breast cancer and 183 controls volunteers without any history of cancer. Also a significant number of healthy individuals were included for allelic frequency in the population studied. Risk of breast cancer was estimated by conditional logistic regression. An association with risk was found for women carrying the MTR A2756G polymorphic allele (AG, P = 0.0036; AG/GG, P = 0.0040), and a protective effect in carriers of the RFC1 G80A polymorphic allele (GA, P = 0.0015; AA, P = 0.0042). Stratifying the data by age (cutoff point of 50 years old), different distributions were observed for breast cancer risk. For women ≤50 years, the risk observed in the presence of the polymorphic allele MTR 2756 (AG/GG) in the general analysis was, restricted to this age group (P = 0.0118). Conversely, for women over 50, the risk of breast cancer development was statistically associated with the MTHFR 677CT genotype, but especially significant was risk associated with the presence of the polymorphic allele of cSHMT C1420T (P = 0.0120) and the protective effect associated with the RFC1 G80A polymorphism allele (P = 0.0021), was restrict to this age group. These data indicate that the cutoff age used (50 years old) was appropriate, since it was able to discriminate risk in each age group in the population studied and also to point to the importance of age in the analyses of cancer-associated polymorphisms.

Polymorphisms of folate pathway enzymes (methylenetetrahydrofolate reductase and thymidylate synthase) and their relationship with thymidylate synthase expression in human astrocytic tumors

Two important polymorphisms of folate cycle enzymes, methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) enhancer region (TSER) 28-bp tandem repeat, are related to risk of various types of cancer, including brain tumors, although there are few studies on this subject. A case-control study of these two polymorphisms in astrocytomas of different grades was carried out using polymerase chain reaction-restriction fragment length polymorphism, also determining the immunohistochemical expression of TS. The MTHFR 677 TT genotype was less associated with astrocytic tumors (odds ratio [OR]=0.00; p=0.0238), but the TSER polymorphism did not show any significant association. Combined genotype TT-double repeats/triple repeats (2R/3R) had a protective effect against astrocytomas (OR=0.00; p=0.0388). Expression of TS protein was observed in the majority of cases, with grade IV tumors being the exception. Moreover, the median H-score for the pilocytic astrocytomas was significantly higher when compared with that for diffuse tumors. There was an inverse correlation between the 2R/2R genotype and the highest TS-expressing tumors, and 3R/3R was relatively more frequent among the tumors grouped in the third and fourth quartiles. Our results provide support for the role of MTHFR and TS polymorphism in gliomagenesis, possibly because of the alteration of DNA methylation and repair status. Moreover, high levels of TS expression were detected in these tumors.

TS and ERCC-1 mRNA expressions and clinical outcome in patients with metastatic colon cancer in CONFIRM-1 and -2 clinical trials

To validate established cutoff levels of thymidylate synthase (TS) and excision repair cross-complementing (ERCC-1) intratumoral mRNA expressions in tumor samples from metastatic colorectal cancer (mCRC) patients treated with PTK787/ZK222584 (PTK/ZK). From 122 samples of patients with mCRC enrolled in CONFIRM-1 (Colorectal Oral Novel Therapy for the Inhibition of Angiogenesis and Retarding of Metastases) or CONFIRM-2, mRNA was isolated of microdissected formalin-fixed paraffin-embedded samples and quantitated using TaqMan-based technology. Existing TS and ERCC-1 cutoff levels were tested for their prognostic value in first-line and second-line therapy. TS expression was associated with overall survival (OS) in first-line, but not second-line therapy. ERCC-1 was associated with OS in patients treated with first-line and second-line FOLFOX4. In first-line FOLFOX4, combination of high TS and/or high ERCC-1 was associated with shorter OS. A correlation was observed between ERCC-1 expression and benefit from PTK/ZK+FOLFOX4 treatment. TS and ERCC-1 expression is associated with clinical outcome in mCRC. Baseline TS and ERCC-1 levels may allow the selection of patients who benefit from FOLFOX4 chemotherapy.

Effect of leucovorin on the antitumor efficacy of the 5-FU prodrug, tegafur-uracil, in human colorectal cancer xenografts with various expression levels of thymidylate synthase

The combination of oral tegafur-uracil (UFT) with leucovorin (LV) is used to treat patients with stage II to III colon cancer based on the results of postoperative randomized studies in which UFT/LV treatment showed an equivalent efficacy to intravenous 5-FU plus LV therapy. However, whether the addition of LV to UFT can elevate the antitumor activity of UFT in colorectal tumors with high expression levels of thymidylate synthase (TS), which affects 5-FU efficacy, remains to be clarified. This study investigated the effect of LV on the antitumor activity of UFT and/or 5-FU prodrugs in low folate diet-fed nude mice using human colorectal cancer xenografts with various expression levels of TS. The addition of LV to UFT resulted in a 55-79% inhibition of tumor growth among 11 types of colorectal tumor xenograft, whereas UFT alone showed 23-67% antitumor activity. Although there was an inverse relationship between the antitumor effect of UFT alone and UFT plus LV and tumoral TS activity, UFT plus LV appeared to have a more potent antitumor effect than UFT alone on colorectal tumors such as Co-3 and KM12C/5-FU with high expression levels of TS. This finding was confirmed by the significant positive correlation between the relative inhibition ratio of UFT/LV to UFT alone and TS levels in tumors. To investigate the reason for the higher efficacy of UFT/LV on colorectal cancer xenografts with high TS activity, intratumoral levels of reduced folates and a ternary complex of TS after oral UFT with or without LV were measured using Co-3 xenografts. Elevated levels of reduced folates and an increased ternary complex of TS in LV-treated tumors were noted. Our results indicate that a combined therapy of UFT with LV may contribute to the treatment of colorectal cancer patients with low and high expression levels of tumoral TS by increased formation of the ternary complex of TS leading to potentiated antitumor efficacy of UFT.

Amplification of thymidylate synthetase in metastatic colorectal cancer patients pretreated with 5-fluorouracil-based chemotherapy

Resistance to 5-fluorouracil (5-FU) represents a major contributor to cancer-related mortality in advanced colorectal cancer patients. Genetic variations and expression alterations in genes involved in 5-FU metabolism and effect have been shown to modulate 5-FU sensitivity in vitro, however these alterations do not fully explain clinical resistance to 5-FU-based chemotherapy. To determine if alterations of DNA copy number in genes involved in 5-FU metabolism-impacted clinical resistance to 5-FU-based chemotherapy, we assessed thymidylate synthetase (TYMS) and thymidine phosphorylase (TYMP) copy number in colorectal liver metastases. DNA copy number of TYMS and TYMP was evaluated using real time quantitative PCR in frozen colorectal liver metastases procured from 62 patients who were pretreated with 5-FU-based chemotherapy prior to surgical resection (5-FU exposed) and from 51 patients who received no pretreatment (unexposed). Gain of TYMS DNA copy number was observed in 18% of the 5-FU exposed metastases, while only 4% of the unexposed metastases exhibited TYMS copy gain (p = 0.036). No significant differences were noted in TYMP copy number alterations between 5-FU-exposed and -unexposed metastases. Median survival time was similar in 5-FU-exposed patients with metastases containing TYMS amplification and those with no amplification. However, TYMS amplification was associated with shorter median survival in patients receiving post-resection chemotherapy (hazard ratio = 2.7, 95% confidence interval = 1.1-6.6; p = 0.027). These results suggest amplification of TYMS amplification as a putative mechanism for clinical resistance to 5-FU-based chemotherapy and may have important ramifications for the post-resection chemotherapy choices for metastatic colorectal cancer.

Clinical, laboratory and molecular factors predicting chemotherapy efficacy and toxicity in colorectal cancer

Colorectal cancer (CRC) treatment has evolved significantly over the last ten years with the use of active chemotherapeutic agents including fluoropyrimidines, oxaliplatin and irinotecan plus targeted monoclonal antibodies bevacizumab, cetuximab and panitumumab. The addition of newer chemotherapeutic agents and targeted therapies has improved patient outcomes at the cost of increased toxicity with not all patients benefiting from these treatments. It is necessary for clinicians to more accurately predict clinical outcomes particularly in the predominantly elderly CRC patient population. This review aims to summarise existing data regarding the use of clinical and laboratory variables plus molecular markers in predicting response, survival and toxicity to chemotherapy agents and targeted monoclonal antibodies currently used in the treatment of CRC.

[Recent developments of pharmacogenomics in the treatment of colorectal cancers]

Colorectal cancer (CCR), which is one of the most common causes of cancer, has benefited from the major advances in the understanding of the intracellular signaling pathways implicated in the initiation, growing and local and metastasis dissemination of tumor, which have occurred during the 20 past years. The pharmacogenomics approach, especially the determination of the genetic polymorphisms, tries to find prognosis and predictive biomarkers permitting to identify patients who could benefit from a particular treatment or those exhibiting higher risks of toxicity. Among the numerous biomarkers, which have been studied, few are currently in use in clinical practice. The phenotyping of DPD and UGT1A1 activities, and to a lesser extent, its genotyping, appears as the most useful tool in terms of prediction of toxicities induced by two major drugs: 5-FU and irinotecan. For oxaliplatin, the determination of the polymorphisms of reparases and detoxification systems such as GSTpi seems interesting, but its exact place should be more defined. It is in the field of targeted therapies that the pharmacogenomics approach seems to be the more relevant. KRAS mutation is a dramatic example of single nucleotide polymorphism, which is able to identify a priori patients that could receive or not an anti-EGFR monoclonal antibody such as cetuximab or panitumumab. It is obvious that pre-clinical identification of molecular biomarkers predictive of the sensitivity of the drug targets, which subsequently implicate the selection of patients and the rational evaluation of responses, will be the cornerstone of any clinical trials concerning targeted therapies. Besides the determination of drug target polymorphisms, it is also important to consider those related to the distribution and metabolism. In this area, the determination of enzymatic activities should recover its place besides the genomic profiling.

Correlation between thymidylate synthase gene variants, RNA and protein levels in primary colorectal adenocarcinomas

This study was designed to compare thymidylate synthase (TS) genotype, mRNA and protein levels in primary colorectal adenocarcinoma, and to examine the correlation between microsatellite instability (MSI) and TS expression. The TS genotype of 68 patients with colorectal cancer was determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis in peripheral blood mononuclear cells and tumour tissue. The TS mRNA levels in tumour tissue were measured by reverse-transcription PCR, and TS protein levels and MSI status were assessed using immunohistochemistry. Significantly higher mRNA and protein levels were observed in patients with the TS 3R/3R versus the 2R/2R and 2R/3R genotypes. There was no correlation between TS single nucleotide polymorphism and TS expression. Individuals homozygous for the six base-pair insertion in the 3'-untranslated region had significantly higher TS mRNA levels than heterozygous and homozygous wild type individuals. The TS mRNA and protein levels were significantly higher in microsatellite unstable tumours compared with microsatellite stable tumours. There was a significant association between the number of TS enhancer region repeats (in blood) and intratumoural TS mRNA and protein levels. A larger case series investigating the role of TS gene polymorphisms as predictors of sensitivity to 5-fluorouracil-based chemotherapy is required.

UGT1A and TYMS genetic variants predict toxicity and response of colorectal cancer patients treated with first-line irinotecan and fluorouracil combination therapy

Background:

The impact of thymidylate synthase (TYMS) and UDP-glucoronosyltransferase 1A (UGT1A) germline polymorphisms on the outcome of colorectal cancer (CRC) patients treated with irinotecan plus 5-fluorouracil (irinotecan/5FU) is still controversial. Our objective was to define a genetic-based algorithm to select patients to be treated with irinotecan/5FU.

Methods:

Genotyping of TYMS (5′TRP and 3′UTR), UGT1A1^*28, UGT1A9^*22 and UGT1A7^*3 was performed in 149 metastatic CRC patients treated with irinotecan/5FU as first-line chemotherapy enrolled in a randomised phase 3 study. Their association with response, toxicity and survival was investigated by univariate and multivariate statistical analysis.

Results:

TYMS 3TRP/3TRP genotype was the only independent predictor of tumour response (OR=5.87, 95% confidence interval (CI)=1.68–20.45; P=0.005). UGT1A1^*28/^*28 was predictive for haematologic toxicity (OR=6.27, 95% CI=1.09–36.12; P=0.04), specifically for neutropenia alone (OR=6.40, 95% CI=1.11–37.03; P=0.038) or together with diarrhoea (OR=18.87, 95% CI=2.14–166.67; P=0.008). UGT1A9^*1/^*1 was associated with non-haematologic toxicity (OR=2.70, 95% CI=1.07–6.82; P=0.035). Haplotype VII (all non-favourable alleles) was associated with non-haematologic toxicity (OR=2.11, 95% CI=1.12–3.98; P=0.02).

Conclusion:

TYMS and UGT1A polymorphisms influence on tumour response and toxicities derived from irinotecan/5FU treatment in CRC patients. A genetic-based algorithm to optimise treatment individualisation is proposed.

Pharmacogenetic assessment of toxicity and outcome in patients with metastatic colorectal cancer treated with LV5FU2, FOLFOX, and FOLFIRI: FFCD 2000-05

PURPOSE

The aim was to investigate whether germline polymorphisms within candidate genes known or suspected to be involved in fluorouracil (FU), oxaliplatin, and irinotecan pathways were associated with toxicity and clinical outcome in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Blood samples from 349 patients included in the Fédération Francophone de Cancérologie Digestive 2000-05 randomized trial, which compared FU plus leucovorin (LV5FU2) followed by FU, leucovorin, and oxaliplatin (FOLFOX) followed by FU, leucovorin, and irinotecan (FOLFIRI; sequential arm) with FOLFOX followed by FOLFIRI (combination arm) in terms of progression-free survival (PFS) and overall survival, were collected. Twenty polymorphisms within the DPD, TS, MTHFR, ERCC1, ERCC2, GSTP1, GSTM1, GSTT1, and UGT1A1 genes were genotyped.

RESULTS

The ERCC2-K751QC allele was independently associated with an increased risk of FOLFOX-induced grade 3 or 4 hematologic toxicity (P = .01). In the sequential arm, TS-5'UTR3RG and GSTT1 alleles were independently associated with response to LV5FU2 (P = .009) and FOLFOX (P = .01), respectively. The effect of oxaliplatin on tumor response increased with the number of MTHFR-1298C alleles (test for trend, P = .008). The PFS benefit from first-line FOLFOX was restricted to patients with 2R/2R (hazard ratio [HR] = 0.39; 95% CI, 0.23 to 0.68) or 2R/3R (HR = 0.59; 95% CI, 0.42 to 0.82) TS-5'UTR genotypes, respectively. Conversely, patients with the TS-5'UTR 3R/3R genotype did not seem to benefit from the adjunction of oxaliplatin (HR = 0.96; 95% CI, 0.66 to 1.40; trend between the three HRs, P = .006).

CONCLUSION

A pharmacogenetic approach may be a useful strategy for personalizing and optimizing chemotherapy in mCRC patients and deserves confirmation in additional prospective studies.

Molecular predictive and prognostic markers in colon cancer

Colorectal cancer remains one of the major cancer related death despite progress in the cytotoxic treatment of colorectal cancer (CRC) over the past decade. The introduction of targeted agents has improved the progression free and overall survival of metastatic disease. However, 40-50% of patients do not experience beneficial effects and it remains a challenge to select patients likely to respond to therapy. Several new molecular predictive and prognostic markers have been identified and are now being translated into routine clinical practice. K-Ras mutation is the first established molecular marker with a lack of response in K-Ras mutated patients treated with an epidermal growth factor receptor (EGFR)-targeted therapy. The validation of predictive and prognostic markers will result in more successful and less toxic therapeutic regimens for cancer patients. This review aims to summarize the most important currently available predictive and prognostic molecular markers in colorectal cancer.

Relationship of polymorphism of the tandem repeat sequence in the thymidylate synthase gene and the survival of stage III colorectal cancer patients receiving adjuvant 5-flurouracil-based chemotherapy

BACKGROUND

The aim of this study was to determine whether the different polymorphisms in the thymidylate synthase (TS) gene, novel G>C single nucleotide polymorphism (SNP) and variable number of tandem repeat (VNTR), may be related with disease-free survival (DFS) in patients with stage III colorectal cancer receiving adjuvant chemotherapy.

METHODS

The study included 201 patients with pathologic TNM stage III colon cancer who received adjuvant 5-fluorouracil (5-FU)-based chemotherapy after surgery. DNA was extracted from fresh tumor tissue and sequenced. Patients with TS genotypes of 2R3G, 3C3G, or 3G3G were assigned to a high expression group, and those with 2R2R, 2R3C, or 3C3C, to a low expression group.

RESULTS

Frequencies of the TS tandem repeat polymorphisms among the tumor genotypes were 6.0% in 2R2R, 25.4% in 2R3R, and 68.7% in 3R3R. The low expression group included 52 patients (25.9%), and the high expression group included 149 patients (74.1%). Groups classified according to possession of VNTR, SNP, and low- or high-expression genotypes did not differ significantly in DFS. In multivariate analysis, only tumor stage showed significant prognostic value (hazard ratio (HR) 2.05, 95% CI = 1.24-3.37, P = 0.005).

CONCLUSIONS

TS polymorphisms do not predict clinical outcome of colorectal cancer patients treated with adjuvant 5-FU-based chemotherapy.

Topoisomerase I expression correlates to response to neoadjuvant irinotecan-based chemoradiation in rectal cancer

Biomarkers may help predict the efficacy of neoadjuvant chemoradiation in patients with rectal cancer. We hypothesized that the expression of topoisomerase I (Topo I) and thymidylate synthase (TS) may help predict the treatment response in patients undergoing irinotecan and capecitabine-based chemoradiation. Patients with rectal cancer (cT3/4Nx or Tx/N+) received neoadjuvant chemoradiotherapy within clinical studies with irinotecan and capecitabine. Samples of normal and tumour tissues were collected before the start of the treatment and during surgical resection. Topo I and TS were measured using real-time PCR. The results of gene expression levels were compared between responders (defined as ypT0-2 ypN0) and nonresponders (ypT3-4 or ypN1/2). A total of 38 patients were analysed, 18 of them were responders. The biopsies of the untreated tumour tissue of responding patients showed a significant higher expression of Topo I compared with nonresponding patients (P = 0.015). Normal tissue did not show this difference (P = 0.126). During chemoradiation, the Topo I expression in tumour tissue of responders decreased significantly. TS did not show any differences between responders and nonresponders before treatment, but a significant decrease in the tumour tissue of responders was noted at the end of the treatment. Our data suggest that Topo I expression in rectal tumour mucosa might serve as a predictor of response to the neoadjuvant irinotecan-based chemoradiation, and hence might be a factor contributing to the development of individualized treatment.

Comparative analysis of thymidylate synthase at the protein, mRNA, and DNA levels as prognostic markers in colorectal adenocarcinoma

BACKGROUND AND OBJECTIVES

To determine the best routinely available molecular methodology for assessing thymidylate synthase (TS) as a prognostic marker in colorectal adenocarcinoma, TS was examined at the protein, mRNA, and DNA levels. Direct comparison of these routinely available assays has not been systematically studied across a large colon cancer patient cohort with long-term follow-up.

METHODS

We studied 150 surgically resected colorectal adenocarcinoma patients who received postoperative 5-Fluorouracil (5-FU) chemotherapy. TS immuunohistochemistry and real-time quantitative RT-PCR and PCR genotyping on patient-matched tumor and normal tissues were performed.

RESULTS

Surprisingly, mRNA values in normal tissue varied from 0.11 to 62.0 and significantly correlated with mRNA values of matched tumor tissues. Although higher tumor/normal ratios of mRNA expression trended toward poorer patient survival, neither this nor TS immunohistochemistry results were statistically significant predictors. TS tumor genotype was generally concordant with matched normal tissues. Further, the 2R/3R genotype of 5'-TSER was significantly correlated with poorer patient survival (P = 0.0249) and was also an independent prognostic marker on multivariate analysis.

CONCLUSION

TS genotyping on paraffin-embedded fixed tissues proved to be the most useful method for prediction of outcome of 5-FU treatment in patients with colorectal adenocarcinoma.

P53 Arg72Pro polymorphism in gastric cancer patients

INTRODUCTION

Polymorphism in codon 72, exon 4 of p53 may alter apoptosis and cancer progression.

PATIENTS AND METHODS

P53 Arg72Pro genotype was assessed by PCR from 84 gastric cancer patients and 185 controls. The control group was comparable in sex, race, age, smoking, and alcohol intake to the cancer group.

RESULTS AND DISCUSSION

There was no difference among the frequency of the alleles or genotypes between the groups. P53 Pro/Pro was associated to a lower risk of metastatic disease (p = 0.02) but not to lymph nodes metastasis or worst prognosis. Arg/Arg or Arg/Pro genotype may be associated to metastatic disease.