Tumour location and efficacy of first-line EGFR inhibitors in KRAS/RAS wild-type metastatic colorectal cancer: retrospective analyses of two phase II randomised Spanish TTD trials

Laterality influence on gene expression of DNA damage repair in colorectal cancer

Colorectal carcinoma (CRC) is the third most common malignancy worldwide, and second in number of deaths in the world. The molecular pathogenesis of CRC is heterogeneous and can affect several genes. Moreover, genomic instability is recognized as an important part of CRC carcinogenesis and is tightly connected to DNA damage response. DNA damage repair (DDR) pathways are intrinsically associated with cancer development and establishment. Traditionally, CRC is considered as one coherent disease, however, new evidence shows that left and right-sided CRC present differences observed in clinical settings, as well as in pre-clinical studies. Therefore, this study aimed to investigate the impact of DDR transcriptional profiles on survival in different sublocations of the colon and rectum using Cox regression, survival analysis and differential gene expression. Right side colon (RSC) has DDR genes' expression associated only with higher risk of death, while left side colon (LSC) and Rectum have most genes' expression associated with lower risk. The pattern is the same with survival analysis. All significant DDR genes had lower expression associated with better survival in RSC, as opposed to LSC and Rectum. Our results demonstrate that RSC is distinctively different from LSC and Rectum. LSC and Rectum have similar DDR expression profiles.

From Dukes-MAC Staging System to Molecular Classification: Evolving Concepts in Colorectal Cancer

This historical review aimed to summarize the main changes that colorectal carcinoma (CRC) staging systems suffered over time, starting from the creation of the classical Duke’s classification, modified Astler–Coller staging, internationally used TNM (T—primary tumor, N—regional lymph nodes’ status, M—distant metastases) staging system, and ending with molecular classifications and epithelial–mesenchymal transition (EMT) concept. Besides currently used staging parameters, this paper briefly presents the author’s contribution in creating an immunohistochemical (IHC)-based molecular classification of CRC. It refers to the identification of three molecular groups of CRCs (epithelial, mesenchymal and hybrid) based on the IHC markers E-cadherin, β-catenin, maspin, and vimentin. Maspin is a novel IHC antibody helpful for tumor budding assessment, which role depends on its subcellular localization (cytoplasm vs. nuclei). The long road of updating the staging criteria for CRC has not come to an end. The newest prognostic biomarkers, aimed to be included in the molecular classifications, exert predictive roles, and become more and more important for targeted therapy decisions.

The efficacy of anti-EGFR therapy in treating metastatic colorectal cancer differs between the middle/low rectum and the left-sided colon

BACKGROUND

Clinically, metastatic rectal cancer has been considered a subset of left-sided colon cancer. However, heterogeneity has been proposed to exist between high and middle/low rectal cancers. We aimed to examine the efficacy of anti-epidermal growth factor receptor (EGFR) treatment for middle/low rectal and left-sided colon cancers.

METHODS

This study enrolled 609 patients with metastatic colorectal cancer who were treated with anti-EGFR therapy. They were divided into groups based on primary tumour locations: the right-sided colon, the left-sided colon or the middle/low rectum. The efficacy of first-line and non-first-line anti-EGFR treatment was analysed. Genomic differences in colorectal cancer data from The Cancer Genome Atlas (TCGA) were investigated and visualised with OncoPrint and a clustered heatmap.

RESULTS

On first-line anti-EGFR treatment, patients with middle/low rectal tumours had significantly lower progression-free survival, overall survival, and overall response rates (6.8 months, 27.8 months and 43%, respectively) than those with left-sided colon cancer (10.1 months, 38.3 months and 66%, respectively). Similar outcomes were also identified on non-first-line anti-EGFR treatment. In TCGA analysis, rectal tumours displayed genetic heterogeneity and shared features with both left- and right-sided colon cancer.

CONCLUSIONS

Anti-EGFR treatment has lower efficacy in metastatic middle/low rectal cancer than in left-sided colon cancer.

High-Grade Inflammation Attenuates Chemosensitivity and Confers to Poor Survival of Surgical Stage III CRC Patients

Background: Heterogeneous clinical and molecular characteristics are reported in colorectal cancer (CRC) with different tumor laterality. However, the outcome of left- and right-sided patients with stage I–III CRC and the role of chronic inflammation in survival differences between them remain unclear.

Method: A prospective study including 1,181 surgical patients with stage I–III CRC was carried out to investigate the involvement of circulating fibrinogen-to-pre-albumin (Alb) ratio (FPR) and primary tumor sidedness in the clinical outcome of those patients. We further investigated the effect of FPR on adjuvant chemotherapy response and recurrence in stage III patients.

Results: Our study showed that the right tumor location was significantly associated with poor recurrence-free survival (RFS) (p = 0.04, adjusted HR = 1.41, 95% CI = 1.02–1.94) and overall survival (OS) (p = 0.04, adjusted HR = 1.55, 95% CI = 1.01–2.38) only in the stage III disease. In these patients, T4 stage distribution (83.39 vs. 70.94%, p < 0.01) within right-sided cases was significantly higher than left-sided patients. Moreover, preoperative FPR within right-sidedness (p < 0.01), T4 stage (p < 0.05), and large cancer bulk (≥5 cm) (p < 0.05) subgroups was significantly elevated compared to their counterparts, and it was gradually rising following the increased cancer bulk (p trend < 0.01). High-FPR distribution (52.30 vs. 27.00%, p < 0.01) within right-sided patients with the stage III disease was significantly higher than that in the left-sided cases. RFS (p_log−rank < 0.01) and OS (p_log−rank < 0.01) of the high-FPR patients were extremely inferior to the low-FPR cases, and the significant associations were observed when they were adjusted by other confounders including primary tumor location (p < 0.01, adjusted HR = 1.96, 95% CI = 1.42–2.70 for RFS; p < 0.01, adjusted HR = 2.44, 95% CI = 1.59–3.75 for OS). Additionally, RFS of adjuvant chemotherapy-treated high-FPR patients was superior to the patients without chemotherapy (p_log−rank = 0.01) but was inferior to the low-FPR patients undergoing the treatment, especially in the 5-FU- and XELOX-treated subgroup.

Conclusion: These findings indicate that chronic high-grade inflammation weakens chemotherapy efficacy and contributes to the poor prognosis of stage III surgical CRC patients.

A Cross-Sectional Study for Evaluation of KRAS and BRAF Mutations by Reverse Dot Blot, PCR-RFLP, and Allele-Specific PCR Methods Among Patients with Colorectal Cancer

BACKGROUND

KRAS and BRAF genes are the biomarkers in Colorectal Cancer (CRC) which play prognostic and predictive roles in CRC treatment. Nowadays, the selection of rapid and available methods for studying KRAS and BRAF mutations in anti-EGFR therapy of patients suffering from CRC plays a significant role. In this study, the mutations of these two oncogenes were evaluated by different methods.

METHODS

This study was performed on 50 Formalin-Fixed Paraffin-Embedded (FFPE) tissue blocks of patients diagnosed with colorectal cancer. After DNA extraction, KRAS and BRAF gene mutations were evaluated using reverse dot blot, and results were compared with PCR-RFLP and allele-specific PCR for KRAS and BRAF mutations, respectively.

RESULTS

KRAS gene mutations were detected in 42% of patients, of which 30% were in codon 12 region, and 12% in codon 13. The most frequent mutations of KRAS were related to G12D and 10% of patients had BRAF mutated genes. The type of KRAS gene mutations could be evaluated by reverse dot blot method. In general, the results of PCR-RFLP and allele-specific PCR were similar to the findings by reverse dot blot method.

CONCLUSION

These findings suggest that PCR-RFLP and allele-specific PCR methods are suitable for screening the presence of the mutations in KRAS and BRAF oncogenes. In fact, another method with more sensitivity is needed for a more accurate assessment to determine the type of mutations. Due to higher speed of detection, reduced Turnaround Time (TAT), and possible role of some KRAS point mutations in overall survival, reverse dot blot analysis seems to be an optimal method.

KRAS and BRAF Mutations as Prognostic and Predictive Biomarkers for Standard Chemotherapy Response in Metastatic Colorectal Cancer: A Single Institutional Study

KRAS mutation is a confirmed predictive biomarker for anti-EGFR monoclonal antibody therapy response for metastatic colorectal cancer. However, its prognosis impact and the predictive potential for first-line standard chemotherapy remains unclear. On the other hand, V600E mutation is the most frequent and studied mutation in the BRAF gene, and it has been associated with a poor outcome of patients and a low response to anti-EGFR treatment. Thus, the aim of this study is to evaluate the role of KRAS and BRAF mutations as prognosis factors and predictive biomarkers for 1st line standard chemotherapy in metastatic colorectal cancer. KRAS mutations and BRAF V600E mutations exhibited a poor outcome (p = 0.021 and p < 0.0001, respectively). Cox multivariate analysis showed that the presence of liver metastasis (HR = 1.595; 95% CI: 1.086–2.343; p = 0.017), KRAS mutation (HR = 1.643; 95% CI: 1.110–2.431; p = 0.013) and BRAF V600E mutation (HR = 5.861; 95% CI: 2.531–13.570; p < 0.0001) were statistically significant co-variables for progression-free survival. Interestingly, patients with KRAS mutations were associated with a poor response to first line standard chemotherapy (p = 0.008). In contrast, the BRAF V600E mutation did not have any impact on the first line standard chemotherapy response (p = 0.540). Therefore, in the present study, we provide new insight on the role of KRAS and BRAF, not only as prognosis biomarkers, but also as first line standard chemotherapy response biomarkers in metastatic colorectal cancer.