Tumor dihydropyrimidine dehydrogenase expression is a useful marker in adjuvant therapy with oral fluoropyrimidines after curative resection of colorectal cancer

The Prognostic and Predictive Value of Dihydropyrimidine Dehydrogenase-Related Indicators in Clinical Outcomes of Chemotherapy in Colorectal Cancer Patients: a Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the third most common cancer worldwide. Predictive biomarkers are needed to predict patients' outcomes and to select a chemotherapy regimen. We assessed whether dihydropyrimidine dehydrogenase (DPD)-related indicators can predict CRC patients' outcomes. We searched the studies in PubMed, EmBase, and the Cochrane Library up to March 4, 2018. We mainly analyzed different CRC patients' outcomes according to specific DPD-related indicators. Twenty-five articles were included in the meta-analysis. The results showed that for disease-free survival (DFS), low DPD expression was significantly superior to high expression (I² = 72%; HR: 1.59; 95%CI: 1.21-2.09; p = 0.001). However, this result had a potential publication bias (Begg's test: p = 0.007; Egger's test: p = 0.004). Among patients treated with chemotherapy, a high thymidylate phosphorylase (TP)/DPD ratio was advantageous for DFS (I² = 63.7%; HR: 0.65; 95%CI: 0.46-0.92; p = 0.015), and this result did not have a publication bias. For overall survival (OS), low DPD expression was superior to high expression (I² = 74.4%; HR: 2.11; 95%CI: 1.48-3.00; p < 0.001), although this result had a publication bias (Egger's test: p = 0.003; Begg's test: p = 0.010). There was no difference in OS according to the TP/DPD ratio (I² = 0%; HR: 0.92; 95%CI: 0.75-1.13; p = 0.420). DFS and OS were better in CRC patients with low DPD expression than in those with high DPD expression. However, because of publication bias, more DPD indicator-related studies, especially with negative results, are still needed. Patients with a high TP/DPD ratio have better DFS but not OS.

Investigating the role of nucleoside transporters in the resistance of colorectal cancer to 5-fluorouracil therapy

Resistance to 5-fluorouracil (5FU) poses a constant challenge to the management of colorectal cancer (CRC). Consistent efforts were called for to identify molecular markers that can effectively predict patients' response. This study investigated the role of nucleoside transporters, particularly human equilibrative nucleoside transporter 1 (hENT1), in predicting clinical treatment outcome with 5FU-based therapy. Expression of a panel of nucleoside transporters in biopsied tumors from 7 CRC patients was measured by real-time PCR prior to 5FU-based chemotherapy. To provide mechanistic support for the role of hENT1 in 5FU resistance, cell viability of Caco-2 cells was measured, following incubation with varying concentrations of 5FU and a hENT1 inhibitor. Biopsied tumors were further subjected to global metabonomic profiling using gas chromatography/mass spectrometry. High hENT1 levels in tumor tissue correlated with poor clinical response to 5FU. Corroborating with the clinical findings, chemical inhibition of hENT1 in Caco-2 cells resulted in an augmentation of 5FU efficacy. Metabonomic profiling revealed that the pretreatment metabotype associated with non-responders to 5FU therapy was distinct from metabotype of responders (partial least-squares discriminant analysis Q(2) (cumulative) = 0.898, R(2)X = 0.513, R(2)Y = 0.996). This is the first clinical report on the relationships of intratumoral expression of nucleoside transporters and tumor metabotype with response to 5FU among CRC patients. Coupled to the in vitro findings, our preliminary data suggested hENT1 to be a potential codeterminant of clinical response to 5FU.

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.

Value of gene polymorphisms as markers of 5-FU therapy response in stage III colon carcinoma: a pilot study

PURPOSE

The role of pharmacogenetics in chemotherapy response in colon carcinoma is controversial. We studied the value of known SNPs in genes involved in 5-FU metabolism as biomarkers of chemotherapy response in patients with stage III colon carcinoma.

METHODS

DNA was isolated from normal colonic tissue of 60 patients with stage III colon carcinoma treated adjuvantly with 5-FU combined with leucovorin. The tested SNPs were validated SNPs on the OPRT, TYMS and DPYD genes and a synonymous SNP on the TYMP gene. Real-time PCR, sequencing and RFLP were used for genotyping.

RESULTS

None of the studied genotypes was associated with any of the tumor or patient characteristics. Moreover, none of the genotypes studied had effect on patient survival.

CONCLUSION

In conclusion, the tested SNPs are not biomarkers of chemotherapy response in our stage III colon cancer patients group.

[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.

Apoptosis signaling proteins as prognostic biomarkers in colorectal cancer: a review

Colorectal cancer is a leading cause of cancer related mortality in the Western world. In recent years, combination 5-fluorouracil based adjuvant chemotherapy as first line treatment of this disease has led to improved disease free and overall survival. However drug resistance, both innate and acquired, remains an obstacle in the effective treatment of this disease. Apoptotic pathways are frequently altered in both tumor progression and drug resistance; therefore proteins associated with this pathway may have potential as prognostic biomarkers for this disease. Identification of clinical biomarkers that are able to identify patients who are more likely to respond to specific chemotherapy will lead to more personalized, effective, and less toxic therapy. This review focuses on the current status of apoptosis related proteins as biomarkers for colorectal cancer and discusses the possible application of systems approaches in this context.

UGT1A1*28 polymorphism predicts irinotecan-induced severe toxicities without affecting treatment outcome and survival in patients with metastatic colorectal carcinoma

BACKGROUND

It is known that the uridine-diphosphoglucuronosyl transferase 1A1 (UGT1A1)*28 polymorphism reduces UGT1A1 enzyme activity, which may lead to severe toxicities in patients who receive irinotecan. This study was conducted to assess the influence of this polymorphism on the efficacy and toxicity of irinotecan treatment in Chinese patients with metastatic colorectal carcinoma (CRC).

METHODS

In total, 128 patients with metastatic CRC who had received previous treatment with irinotecan plus 5-fluorouracil/leucovorin were analyzed retrospectively. Genomic DNA samples were obtained from patients' leukocytes, and genotypes were determined by analyzing the sequence of TATA boxes in the UGT1A1 gene. The influence of the UGT1A1*28 polymorphism on toxicity and treatment outcome was analyzed.

RESULTS

Approximately 20% of patients were identified with the UGT1A1*28 polymorphism, including 15.6% (n = 20 patients) with the thymine-adenine (TA)6/TA7 genotype and 4.7% (n = 6 patients) with the TA7/TA7 genotype. The remaining 79.7% of patients (n = 102) had wild type TA6/TA6. Marked increases in grade 3 or 4 neutropenia (53.8% vs 4.9%; P < .01), neutropenic fever (38.5% vs 3.9%; P < .01), diarrhea (26.9% vs 5.9%; P < .01), and pretreatment bilirubin level (23.1% vs 8.8%; P = .04) were observed in patients who had the TA6/TA7 or TA7/TA7 genotypes. Patients' pretreatment bilirubin levels correlated well with irinotecan-induced neutropenia (P < .01). It was noted that, although the requirement for irinotecan dose reduction was significantly greater in patients who had this genetic variant (42.3% vs 12.7%; P < .01), it did not affect the response rate to irinotecan-based chemotherapy (42.3% vs 45.1%; P = .80), and it did not significantly affect progression-free survival (10 months vs 11 months; P = .94) or overall survival (19 months vs 18 months; P = .84).

CONCLUSIONS

The current data suggested that the UGT1A1*28 polymorphism may be a key determinant for predicting irinotecan-induced severe toxicities without affecting treatment outcome for patients with metastatic CRC. Further prospective studies are warranted for using this polymorphism to optimize irinotecan-based chemotherapy.

The multidisciplinary management of gastrointestinal cancer. The use of molecular markers in the diagnosis and treatment of colorectal cancer

Rapidly growing insights into the molecular biology of colorectal cancer led to high hopes for the identification of molecular markers to be used in optimised and tailored treatment regimens for this disorder. However, no molecular marker has yet made it into daily practice. In this review we will discuss some of the potential molecular markers, focus on the lessons learnt from marker development and identify strategies for the future.

Epidermal growth factor receptor R497K polymorphism is a favorable prognostic factor for patients with colorectal carcinoma

PURPOSE

It has been shown that the R497K polymorphism of the epidermal growth factor receptor (EGFR) has attenuated functions in ligand binding, tyrosine kinase activation, and growth stimulation. Because the activation of EGFR results in an unfavorable prognosis of patients with colorectal carcinoma, a pilot study was conducted to assess the influence of this polymorphism on colorectal carcinoma patients.

EXPERIMENTAL DESIGN

We retrospectively analyzed the effect of the R497K polymorphism of EGFR on clinicopathologic features in 209 colorectal carcinoma patients, including 100 with stage II/III colorectal carcinoma receiving curative surgery and the other 109 with metastatic diseases.

RESULTS

An excellent correlation in codon 497 statuses examined by patients' WBCs and tumor tissues was found but no significant between-group difference in patients with or without colorectal carcinoma (P = 0.97). A marked decrease on EGFR phosphorylation (P < 0.01) and c-Myc activation (P = 0.02) was observed in patients with R497K polymorphism, which is associated with decreased invasion (P = 0.01), lower nodal involvement (P = 0.02), reduced subsequent metastasis (P < 0.01), and longer disease-free (P < 0.01) as well as overall (P < 0.01) survival in stage II/III colorectal carcinoma patients who had received curative surgery. For patients with metastatic colorectal carcinoma, this polymorphism was associated with a higher response to 5-fluorouracil/oxaliplatin treatment (P = 0.02) and a longer survival (P < 0.01). By multivariate analysis, this polymorphism was also identified as an independent prognostic factor (P = 0.03).

CONCLUSIONS

These data suggest that the R497K polymorphism of the EGFR, by reducing its activation and a consequential down-regulation of its target genes, could be a key determinant for reduced tumor recurrence of stage II/III colorectal carcinoma patients receiving curative surgery and a longer survival of patients with stage II/III as well as metastatic colorectal carcinoma.

Predictive and prognostic markers in colorectal cancer

Despite recent advances in the treatment of both early and advanced colorectal cancer, it remains the second leading cause of cancer deaths in the western world. There is, therefore, a pressing need to optimize the use of the currently available systemic therapies and to identify active new agents for the treatment of this disease. Pharmacogenomic studies have shown that genetically determined variability in key cellular functions can influence toxicity, response to treatment and survival. Numerous examples of these single ‘classical’ markers have been identified for a wide range of agents and each has been studied with regard to its effect on response. However, in any individual or tumor it is likely that a number of complex, interacting factors are involved in determining the likelihood of benefit with a given therapeutic agent. Microarray-based gene-expression profiling has allowed the complex range of molecular changes occurring in the cell and surrounding stroma to be assessed in relation to response and prognosis. Predictive gene sets have been developed and, along with other markers, are being assessed in prospective clinical trials. Treatment may soon be individualized by using this technology to predict which patients will benefit from a particular systemic therapy or which are likely to develop recurrence.

The prognostic significance of thymidylate synthase and dihydropyrimidine dehydrogenase in colorectal cancer of 303 patients adjuvantly treated with 5-fluorouracil

Cytotoxic effect of 5-fluorouracil 5-FU is mediated through inhibition of thymidylate synthase (TS), and 5-FU is catabolised by dihydropyrimidine dehydrogenase (DPD). Efficacy of 5-FU may therefore depend on the TS and DPD activity of colorectal cancer. Archival tumour specimens from 303 consecutive patients were analysed for the expression of TS and DPD using immunohistochemistry. All patients were completely resected for colorectal cancer stages II-III and have subsequently received adjuvant treatment with 5-FU. In a multivariate analysis adjusting for the impact of bowel obstruction and vascular tumour invasion, diffuse TS pattern was significantly associated with increased risk of recurrence (hazard ratio (HR) = 1.9; 95% confidence interval (CI): 1.1-3.2; p = 0.02), but without significant association to death (HR = 1.6; 95% CI: 0.9-2.8; p = 0.08). High TS intensity was not significantly associated with lower risk of recurrence (HR = 0.6; 95% CI: 0.3-1.1; p = 0.07) or death (HR = 0.6; 95% CI: 0.3-1.2; p = 0.2). High DPD intensity was significantly associated with increased risk of recurrence (HR = 1.5; 95% CI: 1.1-2.3; p = 0.03) and death (HR = 1.6; 95% CI: 1.1-2.5; p = 0.02). Patients with a combination of low TS and high DPD intensity were at significantly increased risk of both recurrence (HR = 2.1; 95% CI: 1.0-4.2; p = 0.04) and death (HR = 2.0; 95% CI: 1.0-4.0; p = 0.05). No relationship between tolerability and toxicity of 5-FU and TS and DPD expression was found. It is concluded that characterizing colorectal carcinomas by TS and DPD expression may disclose subsets of patients with significantly greater risk of disease recurrence and early death. This may be utilized in the selection of patients for treatment approaches and for decision on follow-up programs.

Drug resistance, predictive markers and pharmacogenomics in colorectal cancer

Resistance to chemotherapy limits the effectiveness of current cancer therapies, including those used to treat colorectal cancer, which is the second most common cause of cancer death in Europe and the United States. 5-Fluorouracil-based chemotherapy regimens are the standard treatment for colorectal cancer in both the adjuvant and advanced disease settings. Drug resistance is thought to cause treatment failure in over 90% of patients with metastatic cancer, while drug resistant micrometastic tumour cells may also reduce the impact of adjuvant chemotherapy treatment. The identification of panels of biomarkers that not only identify those patients most likely to benefit from chemotherapy treatment, but also which chemotherapies to use, would be a major advance. In this review, we describe molecular mechanisms of drug resistance that may be relevant to colorectal cancer. We also describe the results of predictive biomarker studies in this disease. Finally, we discuss how pharmacogenomics and other high through-put technologies may impact on the clinical management of colorectal cancer in the future.

Carboxylesterase isoform 2 mRNA expression in peripheral blood mononuclear cells is a predictive marker of the irinotecan to SN38 activation step in colorectal cancer patients

PURPOSE

Irinotecan (CPT11) is a prodrug activated in humans mainly by carboxylesterase 2 (CES2) generating the SN38 metabolite responsible for the drug efficacy and toxicity. The interpatients variability in CPT11 activation step could cause unpredictable toxicity. To identify a predictive molecular marker for CPT11 activation in cancer patients, we investigated the CES2 mRNA expression in peripheral blood mononuclear cells (PBMC) and correlated it to CPT11 activation rate, toxic effects, and response.

EXPERIMENTAL DESIGN

Forty-five colorectal cancer patients were treated with a CPT11-including regimen (FOLFIRI). CES2 mRNA expression in PBMC was quantified by reverse transcription-PCR in real time. Plasma concentrations of CPT11, SN38, and SN38-glucuronide were determined by high-performance liquid chromatography and the pharmacokinetic variables calculated adopting the noncompartmental model. Toxicity was evaluated by the National Cancer Institute Common Toxicity Criteria scale and response by the WHO criteria.

RESULTS

A high interindividual variability in CES2 mRNA relative expression was observed (median, 1.45; range, 0.01-28.21). CES2 mRNA expression level was significantly associated with CPT11 activation ratio [(AUC(SN38) + AUC(SN38G))/AUC(CPT11)]. Patients with CES2 mRNA expression above the median cutoff value presented an activation ratio higher (median, 0.25; range, 0.15-0.42) than those with CES2 mRNA below the median (median, 0.20; range, 0.10-0.40; P = 0.013). This was associated with a nonsignificant trend of 1.34-fold increase of SN38 AUC in the group of patients with high CES2 mRNA expression (mean, 1.03 +/- 0.62 versus 0.77 +/- 0.32 micromol/L hour). Eight of 23 high CES2 mRNA-expressing patients (34.8%) developed grade 3 to 4 neutropenia or diarrhea compared with 2 of 22 (9.1%) in the low CES2-expressing group (P = 0.071).

CONCLUSION

Our data support a predictive power of CES2 mRNA expression in PBMC for the activation rate of CPT11.

Phase II study of tailored chemotherapy for advanced colorectal cancer with either 5-fluouracil and leucovorin or oxaliplatin and irinotecan based on the expression of thymidylate synthase and dihydropyrimidine dehydrogenase

BACKGROUND

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are essential enzymes for 5-fluorouracil (5-FU) metabolism. In patients with advanced colorectal cancer (ACRC), retrospective studies have shown that low expression levels of TS and DPD correlated with response to 5-FU. We performed a prospective study in which the choice of first-line chemotherapy with either 5-FU or a non-5-FU containing regimen was based on TS and DPD expression.

PATIENTS AND METHODS

Fresh-frozen samples of metastases were obtained from 58 previously untreated patients with ACRC. mRNA expression of TS and DPD was quantified using an RT-PCR assay. Patients with low tumor expression of both TS and DPD received weekly bolus 5-FU/leucovorin (LV) 500 mg/m2 (group A); patients with high TS and/or DPD received 3-weekly oxaliplatin 85 mg/m2 and irinotecan 200 mg/m2 (group B). After progression, cross-over to the alternative regimen was attempted.

RESULTS

Of 53 eligible patients, 31 had tumors with both low TS and low DPD, and were treated in group A. A response was observed in 11 patients [35%; 95% confidence interval (CI) 19% to 54%]. Cross-over to second-line oxaliplatin/irinotecan resulted in a partial response in two out of 16 patients (13%; 95% CI 1% to 38%). In group B, four out of 22 patients responded (18%; 95% CI 5% to 40%), while no responses were observed in 12 patients after cross-over to 5-FU/LV (0%; 95% CI 0% to 28%).

CONCLUSIONS

Prospective selection of 5-FU/LV chemotherapy based on low TS and DPD expression in patients with ACRC did not confirm the high response rates reported in retrospective studies. The procedure of obtaining metastatic tissue and quantitation of enzymes appeared feasible but cumbersome. Before assessing the clinical utility of a predictive marker in a randomized trial, future studies should focus on prospective validation of the assay in a large and well defined population.

Have we made progress in pharmacogenomics? The implementation of molecular markers in colon cancer

For the last 40 years, 5-fluorouracil (5-FU) has remained the treatment of choice in both the adjuvant and advanced treatment of colorectal cancer (CRC). However, 5-FU monotherapy produces response rates of only 10–20% in the advanced setting. 5-FU has been combined with newer agents, such as oxaliplatin and irinotecan, and this has significantly increased response rates to 40–50% in the advanced setting. More recently, novel biological agents, such as the monoclonal antibodies targeting either the epidermal growth factor receptor or vascular endothelial growth factor, have shown to provide additional clinical benefit for patients with metastatic CRC. A number of predictive markers have been identified for CRC to date. However, their usefulness as individual markers of response has led to somewhat inconclusive results. Therefore, there is a need to identify panels of predictive markers of response to therapy for advanced CRC, in order to improve these disappointing response rates. The advent of high-throughput methodologies, such as microarrays, enables tumor samples to be profiled on a global scale. This technology has been utilized to develop predictive markers for a wide range of tumor types to date, and hopefully this technology can be translated into the CRC setting with the hope of predicting the response of each individual tumor to chemotherapy.

Role of Genomic Markers in Colorectal Cancer Treatment

For the last four decades, fluorouracil (FU) has been the main treatment of choice in colorectal cancer (CRC) in both the advanced and adjuvant settings. In the advanced setting, FU monotherapy produces response rates of only 10% to 20%. Furthermore, in resected stage III CRC, FU monotherapy has increased overall survival by only 20%. The combination of FU with newer therapies such as oxaliplatin and irinotecan has significantly improved response rates to 40% to 50%. Despite these improvements, more than half of advanced CRC patients derive no benefit from treatment; this is due to either acquired or inherent drug resistance. This review aims to highlight the current prognostic and predictive markers that have been identified for CRC to date. The limited use of these predictive markers underscores the importance of and need for multiple marker testing in order to improve response rates and decrease toxicity. This review will also focus on high throughput methods to identify panels of predictive markers for CRC, which ultimately aim to tailor treatment according to an individual patient and tumor profile.