Predictive Value of MSH2 Gene Expression in Colorectal Cancer Treated with Capecitabine

Genomic and epigenomic biomarkers in colorectal cancer: From diagnosis to therapy

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States. Despite ongoing efforts aimed at increasing screening for CRC and early detection, and development of more effective therapeutic regimens, the overall morbidity and mortality from this malignancy remains a clinical challenge. Therefore, identifying and developing genomic and epigenomic biomarkers that can improve CRC diagnosis and help predict response to current therapies are of paramount importance for improving survival outcomes in CRC patients, sparing patients from toxicity associated with current regimens, and reducing the economic burden associated with these treatments. Although efforts to develop biomarkers over the past decades have achieved some success, the recent availability of high-throughput analytical tools, together with the use of machine learning algorithms, will likely hasten the development of more robust diagnostic biomarkers and improved guidance for clinical decision-making in the coming years. In this chapter, we provide a systematic and comprehensive overview on the current status of genomic and epigenomic biomarkers in CRC, and comment on their potential clinical significance in the management of patients with this fatal malignancy, including in the context of precision medicine.

The clinical relevance of gene expression based prognostic signatures in colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent cancers, with more than one million new cases every year. In the last few decades, several advancements in therapeutic and preventative levels have reduced the mortality rate, but new biomarkers are required for improved prognosis. The alterations at the genetic and epigenetic level have been recognized as major players in tumorigenesis. The products of gene expression in the form of mRNA, microRNA, and long-noncoding RNA, have started to emerge as important regulatory molecules, playing an important role in cancer. Gene-expression based prognostic risk scores, which quantify and compare their expression, have emerged as promising biomarkers with enormous clinical value. These composite multi-gene models in which more than one gene is used to predict prognosis have been shown to be significantly effective in identifying patients with multiple clinico-pathological risks like overall mortality, response to chemotherapy, risk of metastasis, etc. The advent of microarray and advanced sequencing technologies have led to the generation of large datasets like TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus), which have fueled the search for new biomarkers. Continuous evaluation of these candidate biomarkers in clinical settings is promising to improve the management of CRC. These composite gene signatures provide potential in identifying high-risk patients, which might help clinicians to better manage these patients and design appropriate personalized therapeutic interventions. In this review, we emphasize on composite prognostic scores from diverse resources with clinical utility in CRC.

Predictive Biomarkers in Metastatic Colorectal Cancer: A Systematic Review

PURPOSE

The development and use of predictive biomarkers to guide treatment decisions are paramount not only for improving survival in patients with metastatic colorectal cancer (mCRC), but also for sparing them from unnecessary toxicity and reducing the economic burden of expensive treatments. We conducted a systematic review of published studies and evaluated the predictive biomarker landscape in the mCRC setting from a molecular and clinical viewpoint.

METHODS

Studies analyzing predictive biomarkers for approved therapies in patients with mCRC were identified systematically using electronic databases. Preclinical studies and those providing no relevant information were excluded.

RESULTS

A total of 173 studies comprising 148 biomarkers were selected for final analysis. Of all the biomarkers analyzed, 1.4% (two of 148) were explored in a prospective manner, whereas 98.6% (146 of 148) were evaluated in retrospective studies. Of the latter group, 78.8% (115 of 146) were not tested in subsequent phases, 9.6% (14 of 146) were tested in other retrospective cohorts, 8.9% (13 of 146) were retrospectively tested in at least one or more randomized cohorts, and only 2.7% (four of 146) were prospectively tested in a clinical trial. Finally, only 1.4% (two of 148) were validated sufficiently and are recognized as biomarkers for guiding treatment decision making in patients with mCRC. These markers were RAS mutational status for anti-EGFR antibodies and microsatellite instability status for anti-programmed cell death-1 drugs.

CONCLUSION

Despite notable efforts to identify predictive biomarkers for various therapies used in the mCRC setting, because of a lack of data beyond retrospective studies and successful biomarker-driven approaches, only two molecular biomarkers have thus far found their translation into the clinic, highlighting the imperative need for implementing novel strategies and additional research in this clinically important field.

Prognostic Value of Mismatch Repair Genes for Patients With Colorectal Cancer: Meta-Analysis

DNA mismatch repair was proposed to play a pivotal role in the development and prognosis of colorectal cancer. However, the prognostic value of mismatch repair on colorectal cancer is still unknown. The PubMed, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched. The articles about mismatch repair (including hMLH1, hMSH2, hMSH3, hMSH6, hPMSH1, and hPMSH2) deficiency for the prognosis of patients with colorectal cancer were included in the study. The hazard ratio and its 95% confidence interval were used to measure the impact of mismatch repair deficiency on survival time. Twenty-one articles were included. The combined hazard ratio for mismatch repair deficiency on overall survival was 0.59 (95% confidence interval: 0.50-0.69) and that on disease-free survival was 0.57 (95% confidence interval: 0.43-0.75). In subgroup analysis, there were a significant association between overall survival and mismatch repair deficiency in Asian studies (hazard ratio: 0.67; 95% confidence interval: 0.50-0.91) and Western studies (hazard ratio: 0.56; 95% confidence interval: 0.46-0.67). For disease-free survival, the hazard ratios in Asian studies and Western studies were 0.55 (95% confidence interval: 0.38-0.81) and 0.62 (95% confidence interval: 0.50-0.78), respectively. Our meta-analysis indicated that mismatch repair could be used to evaluate the prognosis of patients with colorectal cancer.

Gene expression of the mismatch repair gene MSH2 in primary colorectal cancer

Microsatellite instability (MSI) is caused by defective mismatch repair (MMR) and is one of the very few molecular markers with proven clinical importance in colorectal cancer with respect to heredity, prognosis, and treatment effect. The gene expression of the MMR gene MSH2 may be a quantitative marker for the level of MMR and a potential molecular marker with clinical relevance. The aim was to investigate the gene expression of MSH2 in primary operable colorectal cancer in correlation with MSI, protein expression, and promoter hypermethylation. In a cohort of 210 patients, the primary tumor and lymphnode metastases were analyzed with immunohistochemistry, methylation and MSI analyses, and quantitative polymerase chain reaction (PCR). The median gene expression of MSH2 was 1.00 (range 0.16-11.2, quartiles 0.70-1.51) and there was good agreement between the gene expression in primary tumor and lymph node metastasis (Spearman's rho = 0.57, p < 0.001, n = 73). The validity of gene expression analysis was made probable by a significant correlation to protein expression (p = 0.005). MSI was most often caused by deficient MLH1 and was not correlated to MSH2 expression. Hypermethylation of the MSH2 gene promoter was only detected in 14 samples and only at a low level with no correlation to gene expression. MSH2 gene expression was not a prognostic factor for overall survival in univariate or multivariate analysis. The gene expression of MSH2 is a potential quantitative marker ready for further clinical validation.

SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK are prognosis-related in colorectal cancer

AIM: To investigate the expression of markers that are correlated with the prognosis of colorectal cancer (CRC) patients.

METHODS: One hundred and fifty-six CRC patients were followed up for more than 3 years after radical surgery. Immunohistochemical (IHC) analysis was performed to detect the expression of 14 pathway-related markers (p53, APC, p21ras, E-cadherin, endothelin-B receptor, Shp2, ADCY-2, SPARCL1, neuroligin1, hsp27, mmp-9, MAPK, MSH2 and rho) in specimens from these patients. Bioinformatics analysis involving a Support Vector Machine (SVM) was used to determine the best prognostic model from combinations of these markers.

RESULTS: Seven markers (SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK) were significantly related to the prognosis and clinical pathological features of the CRC patients (P < 0.05). Prognostic models were established through SVM from combinations of these 7 markers and proved able to differentiate patients with dissimilar survival, especially in stage II/III patients. According to the best prognostic model, the p53/SPARCL1 model, patients having high p53 and low SPARCL1 expression had about 50% lower 3-year survival than others (P < 0.001).

CONCLUSION: SPARCL1, Shp2, MSH2, E-cadherin, p53, ADCY-2 and MAPK are potential prognostic markers in CRC. A p53/SPARCL1 bioinformatics model may be used as a supplement to tumor-nodes-metastasis staging.

Clinical significance of microsatellite instability for stage II or III colorectal cancer following adjuvant therapy with doxifluridine

Microsatellite instability (MSI) is a molecular marker that can provide valuable prognostic information for colorectal cancer (CRC). However, the predictive role of the MSI status remains less clear than its role in prognostication due to mixed results from previous studies. Therefore, this study investigated the usefulness of the MSI status as a predictive factor for stage II or III CRC patients who received adjuvant doxifluridine therapy. Among 3030 patients with CRC who underwent surgical resection between 1997 and 2006, 564 patients were diagnosed with stage II or III, and adjuvant doxifluridine therapy was administered to 394 patients (70.0%). The MSI status was assessed using the markers BAT25 and BAT26, and samples with instability at both markers were scored as exhibiting high-frequency MSI (MSI-H). Among the 564 patients, 290 patients (51.4%) had stage II, and MSI-H was found in 41 patients (7.3%). With a median follow-up duration of 35.1 months (range, 0.5-135.2), the 5-year overall survival (OS) rate and relapse-free survival (RFS) rate were 87.5 and 76.2%, respectively. MSI-H showed a favorable survival trend for OS (P = 0.098) and significant survival benefit for RFS (P = 0.037) in all patients. In a univariate analysis, the doxifluridine-treated patients with MSI-H showed improved RFS compared to those with low or stable MSI (MSI-L/S) (P = 0.036), while the MSI status was not significantly associated with OS (P = 0.107). In a multivariate analysis, MSI-H was not significantly associated with RFS (Hazard ratio = 2.467, P = 0.125). In conclusion, this study confirmed the positive prognostic role of MSI-H. However, MSI-H patients with stage II or III CRC did not seem to benefit from doxifluridine adjuvant therapy.

The predictive value of genetic variations in the vascular endothelial growth factor A gene in metastatic colorectal cancer

Single-nucleotide polymorphisms (SNPs) in the vascular endothelial growth factor A (VEGF-A) gene may have clinical implications. The aim of this study was to investigate the possible predictive value of the VEGF-A SNPs, in patients with metastatic colorectal cancer (mCRC) treated with first-line capecitabine and oxaliplatin (XELOX). The study included 72 patients with mCRC. Genomic DNA was isolated from whole blood, and SNPs were analyzed by PCR. SNPs were correlated with response and progression-free survival (PFS). Haplotypes were estimated using the PHASE program. Response was observed in 21% of the patients with the -2578 CA genotype compared with 59% of the patients with CC+AA, P=0.002, in 26% of the patients with the -460 CT genotype compared with 57% with CC+TT, P=0.01, and in 27% of the patients with the +405 GC genotype compared with 54% with GG+CC, P=0.02. Two SNPs were significantly related to PFS. A haplotype with a significant relationship to response was identified. The results demonstrated obvious relationships between genetic variations in the VEGF-A gene and response to first-line XELOX in patients with mCRC, which translated to a significant difference in PFS. The results call for validation in a larger cohort of patients.

The effect of DNA mismatch repair (MMR) status on oxaliplatin-based first-line chemotherapy as in recurrent or metastatic colon cancer

Colon cancer with DNA mismatch repair (MMR) defects reveals distinct clinical and pathologic features, including a better prognosis but reduced response to 5-fluorouracil (5-FU)-based chemotherapy. A current standard treatment for recurrent or metastatic colon cancer uses capecitabine plus oxaliplatin (CAPOX), or continuous-infusion fluorouracil plus oxaliplatin (FOLFOX). This study investigated the effect of MMR status on the treatment outcomes for CAPOX and FOLFOX as first-line combination chemotherapy in recurrent or metastatic colon cancer. We analyzed 171 patients who had been treated with CAPOX or FOLFOX as first-line combination chemotherapy in recurrent or metastatic colon adenocarcinoma between February 2004 and July 2008. Tumor expression of the MMR proteins, MLH1 and MSH2, was detected by immunohistochemistry (IHC) in surgically resected tumor specimens. The microsatellite instability (MSI) was analyzed by polymerase chain reaction (PCR) amplification, using fluorescent dye-labeled primers specific to microsatellite loci. Tumors with MMR defect were defined as those demonstrating a loss of MMR protein expression (MMR-D) and/or a microsatellite instability-high (MSI-H) genotype. In all, 75 patients (44%) received FOLFOX, and 96 patients (56%) received CAPOX as first-line combination chemotherapy. The incidence of colon cancer with MMR defect was 10/171 (6%). Colon cancers with MMR defect (MSI-H and/or MMR-D) are more commonly located in proximal to the splenic flexure (p=0.03). The MMR status did not significantly influence the overall response (p=0.95) to first-line CAPOX or FOLFOX treatment in patients with recurrent or metastatic colon cancer. According to the MMR status, there was no significant difference for PFS (p=0.50) and OS (p=0.47) in patients with recurrent or metastatic colon cancer treated with first-line CAPOX or FOLFOX. In colon cancers with MMR defect, there was no significant difference for PFS (p=0.48) and OS (p=0.56) between CAPOX and FOLFOX as first-line combination chemotherapy. However, in MMR intact, there was significant difference for OS between CAPOX and FOLFOX (p=0.04). OS was significantly better in patients treated with CAPOX when compared to patients with FOLFOX. The MMR status does not predict the effect of oxaliplatin-based combination chemotherapy as 1st line in recurrent or metastatic colon cancers. CAPOX in the first-line treatment of recurrent or metastatic colon cancer with MMR intacts showed a superior OS compared with FOLFOX unlike colon cancer with MMR defects.

Does microsatellite instability predict the efficacy of adjuvant chemotherapy in colorectal cancer? A systematic review with meta-analysis

BACKGROUND

Microsatellite instability (MSI) status in predicting the efficacy of adjuvant chemotherapy in colorectal cancer remains controversial.

MATERIALS AND METHODS

Studies were identified through PubMed, Embase and ASCO proceedings with a combination of keywords (colorectal cancer, chemotherapy and MSI).

RESULTS

A MA was performed for treated and non-treated MSI population on seven studies. Statistical calculations were performed on 7 studies representing 3690 patients; mean age: 65.5 years; 810 stage II and 2444 stage III (75%). MSI-high (MSI-H) was found in 454 patients (14% of the global population), and microsatellite stable (MSS) in 2871. A total of 1444 patients received 5-fluorouracil (5FU)-based chemotherapy, whereas 1518 patients did not. For MSI-H patients, there was no statistically significant difference for RFS whether or not they received chemotherapy (5 studies); HR RFS: 0.96 (95% confidence interval (CI): 0.62-1.49); HR OS (6 studies): 0.70 (95% CI: 0.44-1.09; p=0.12). Elsewhere, we found a significant interaction between MSI status (MSI-H or MSS) and therapeutic status suggesting a lesser benefit for MSI-H than for MSS patients (HR interaction RFS: 0.77 (95% CI: 0.67-0.87)).

CONCLUSION

We found similar RFS for treated and untreated MSI-H patients, showing that MSI-H status, in addition to being a good prognostic factor is also a predictive factor of non response.

Microsatellite instability: a predictive marker in metastatic colorectal cancer?

Microsatellite instability (MSI) status is a good prognostic factor for colorectal cancer (CRC), but its predictive value for chemosensitivity remains controversial. We recently performed a meta-analysis (MA) in adjuvant setting showing that MSI high (MSI-H) status did not predict the efficacy of chemotherapy. Studies were identified by electronic search through PubMed, Embase and ASCO proceedings online databases, using several keywords (colorectal cancer, chemotherapy, microsatellite instability). For each study, we calculated the ratio of response rate, complete and partial responses divided by stable disease and progression. Our MA dealt with the predictive value of MSI status on the effect of metastatic chemotherapy using various combinations of 5FU, oxaliplatin or CPT11. From 159 articles and 76 abstracts, we selected only seven independent studies. Data were analysed with a random-effect model (due to heterogeneity between studies) using EasyMA software. Statistical calculations were performed on five studies representing 860 patients (mean age 63 years; 87 MSI-H; 733 microsatellite stable [MSS] tumors). A total of 287 patients received 5FU-based chemotherapy, whereas 574 patients received combinations of 5FU or capecitabine with oxaliplatin and/or irinotecan. Our MA found no benefit of metastatic chemotherapy in terms of response rate for MSI-H patients compared with MSS patients. The global hazard ratio for response rate was 0.83 (95% confidence interval: 0.95; 0.65-1.05; p = 0.11). In conclusion, MSI status did not predict the effect of chemotherapy for metastatic CRC. Metastatic chemotherapy had a similar effect on both MSI-H or on MSS tumors.