BRAF Mutations In Colorectal Carcinoma Research Articles

Frequency of KRAS and BRAF mutations in colorectal carcinoma and their association with clinical-pathological characteristics in a tertiary hospital in Kenya.

Colorectal carcinoma is a leading cause of cancer morbidity and mortality globally. Its management includes the use of targeted therapy which require assessment for biomarkers to choose eligible patients. KRAS and BRAF mutations are biomarkers predictive of response to anti-EGFR therapy. This study aimed at determining the frequency of BRAF V600E and KRAS exon 2,3,4 mutations in colorectal carcinoma patients at the Aga Khan University Hospital Nairobi, Kenya. Study participants were patients who had colectomy for colorectal carcinoma. They were identified from the laboratory information system. The patients age, gender and tumor location were determined from the medical records. The histological diagnosis, pathological tumor and nodal stage were confirmed by examining hematoxylin and eosin-stained slides prepared from the colectomy specimen. DNA was extracted from the specimens using Qiagen QIAamp DNA FFPE Tissue Kit and PCR performed using EntroGen KRAS/BRAF mutation analysis kit following manufacturer's protocol. One hundred fourteen patients were enrolled. Colorectal carcinoma was significantly more common in males than females. The mean age at diagnosis was 58 years. Majority of the tumors were in the right colon, were of pathological tumor stage T3 and had nodal involvement. Forty six percent (46%) of the cases had KRAS mutations while 5.3% had BRAF V600E mutation. KRAS mutation was associated with a high pathological tumor stage and nodal involvement. Colorectal carcinoma in our patients is more common in males and tend to occur at a younger age. The patients tend to have a high tumor pathological stage and nodal involvement at diagnosis. The high frequency of KRAS exon 2,3,4 mutation and low frequency of BRAF V600E mutations is similar to what has been reported in literature.

Enrichment of Bacteroides fragilis and enterotoxigenic Bacteroides fragilis in CpG island methylator phenotype-high colorectal carcinoma

ObjectivesData support that enterotoxigenic Bacteroides fragilis (ETBF) harbouring the Bacteroides fragilis toxin (bft) gene may promote colorectal tumourigenesis through the serrated neoplasia pathway. We hypothesized that ETBF may be enriched in colorectal carcinoma subtypes with high-level CpG island methylator phenotype (CIMP-high), BRAF mutation, and high-level microsatellite instability (MSI-high). MethodsQuantitative PCR assays were designed to quantify DNA amounts of Bacteroides fragilis, ETBF, and each bft gene isotype (bft-1, bft-2, or bft-3) in colorectal carcinomas in the Health Professionals Follow-up Study and Nurses' Health Study. We used multivariable-adjusted logistic regression models with the inverse probability weighting method. ResultsWe documented 4476 colorectal cancer cases, including 1232 cases with available bacterial data. High DNA amounts of Bacteroides fragilis and ETBF were positively associated with BRAF mutation (p ≤ 0.0003), CIMP-high (p ≤ 0.0002), and MSI-high (p < 0.0001 and p = 0.01, respectively). Multivariable-adjusted odds ratios (with 95% confidence interval) for high Bacteroides fragilis were 1.40 (1.06–1.85) for CIMP-high and 2.14 (1.65–2.77) for MSI-high, but 1.02 (0.78–1.35) for BRAF mutation. Multivariable-adjusted odds ratios for high ETBF were 2.00 (1.16–3.45) for CIMP-high and 2.86 (1.64–5.00) for BRAF mutation, but 1.09 (0.67–1.76) for MSI-high. Neither Bacteroides fragilis nor ETBF was associated with colorectal cancer-specific or overall survival. DiscussionThe tissue abundance of Bacteroides fragilis is associated with CIMP-high and MSI-high, whereas ETBF abundance is associated with CIMP-high and BRAF mutation in colorectal carcinoma. Our findings support the aetiological relevance of Bacteroides fragilis and ETBF in the serrated neoplasia pathway.

A Systematic Review and Meta-analysis on the Occurrence of Biomarker Mutation in Colorectal Cancer among the Asian Population.

Globally, colorectal carcinoma (CRC) is the third most common cancer and the third major cause of cancer-related death in both sexes. KRAS and BRAF mutations are almost mutually exclusively involved in the pathogenesis of CRC. Both are major culprits in treatment failure and poor prognosis for CRC. Method. A systematic review and meta-analysis of various research was done following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. This trial is registered with PROSPERO CRD42021256452. The initial search included 646 articles; after the removal of noneligible studies, a total of 88 studies was finally selected. Data analysis was carried out using OpenMeta Analyst and Comprehensive Meta-Analysis 3.0 (CMA 3.0) software to investigate the prevalence of KRAS and BRAF mutations among patients with CRC in Asia. Results. The meta-analysis comprises of 25,525 sample sizes from Asia with most being male 15,743/25525 (61.7%). Overall prevalence of KRAS mutations was (59/88) 36.3% (95% CI: 34.5-38.2) with I2 = 85.54% (P value < 0.001). In 43/59 studies, frequency of KRAS mutations was majorly in codon 12 (76.6% (95% CI: 74.2–78.0)) and less in codon 13 (21.0% (95% CI: 19.1-23.0)). Overall prevalence of BRAF mutations was 5.6% (95% CI: 3.9-8.0) with I2 = 94.00% (P value < 0.001). When stratified according to location, a higher prevalence was observed in Indonesia (71.8%) while Pakistan has the lowest (13.5%). Conclusion. Total prevalence of KRAS and BRAF mutations in CRC was 36.6% and 5.6%, respectively, and the results conformed with several published studies on KRAS and BRAF mutations.

BRAF mutation: Current and future clinical pathological applications in colorectal carcinoma.

The aims are to review the relevance of the BRAF mutations in the clinical settings of colorectal carcinoma. All the literature concerning BRAF mutations and colorectal carcinoma published in PubMed from 2010 to 2018 was reviewed. Multiple variants of BRAF mutations exist in colorectal cancer, the most common type being V600E. The mutation is found in 5 to 15% of colorectal carcinomas and is less common in Asian populations. BRAF mutations are linked with older age, female gender, cigarette smoking and are more common in the right (proximal) portion of the large intestine. BRAF mutations are associated with carcinomas of high histological grade and advanced cancer stages. Often BRAF mutated carcinomas demonstrate adverse histological features such as lymphovascular invasion, perineural invasion, tumour budding and lymph node metastases. BRAF mutations are found in serrated polyposis syndrome and have a negative correlation with hereditary nonpolyposis colorectal cancer (HNPCC). An array of methods of detection of BRAF mutation in colorectal carcinoma are available, such as immunohistochemistry and next generation sequencing, etc. Combinatorial approaches involving anti-BRAF therapies targeting both MAPK signalling as well as the PI3K/mTOR pathway could be a new approach for treatment of metastatic colorectal carcinoma. To conclude, BRAF mutation is important in the pathogenesis of colorectal cancer. Further research on the detection method as well as its role in target therapy will help to improve the management of patients with colorectal cancer.

A study of BRAF mutation in colorectal carcinoma in Indian population.

BRAF mutation has been extensively studied and associated with various tumors. Targeted therapeutic intervention against BRAF mutation is established modality against many such tumors. Various studies have estimated that the prevalence of BRAF mutation in colorectal carcinoma (CRC) is 5%-25%. Considering epidemiology differences from Western population and paucity of studies on BRAF mutation in CRC in Asian patients, the present study was done to study the BRAF mutation in CRC in Indian population. The aim is to study the distribution of BRAF mutation and its correlation with the American Joint Committee on Cancer (AJCC) stage, grade, and other clinicopathological parameters in CRC. This was a cross-sectional study. Immunohistochemistry study was done using BRAFV600E monoclonal antibody (Clone VE1) for 65 consecutive cases of CRC in a tertiary care center. The results were statistically analyzed using SPSS version 2.0. This study found that BRAF mutation is not significantly present in CRC as only 4.6% of cases were positive for BRAFV600E mutation. However, there was statistically significant relation between increasing AJCC stage and BRAF mutation. This study concluded that BRAF mutation is not prevalent in Indian population with CRC. However, it is significantly related with advanced AJCC stages.

BRAF mutation is associated with poor clinicopathological outcomes in colorectal cancer: A meta-analysis.

Background/Aims:The clinical relevance of the BRAF mutation in colorectal carcinoma (CRC) remains controversial. We performed a comprehensive meta-analysis to evaluate the precise relationship of BRAF mutation to clinicopathological features.Materials and Methods:A systematic search of the electronic databases, including PubMed, the Web of Knowledge, and the China Journal Net was performed between January 2005 and December 2015. Outcomes of interest included gender, tumor site, tumor differentiation, node involvement, tumor size, and AJCC stage. We calculated the pooled odds ratios (ORs) or risk ratios with 95% confidence intervals (CIs) for each study using a random or fixed-effect model.Results:Twenty-five studies with a total of 13208 patients were included. BRAF mutation-positive CRC patients were 1464 (11.1%). Our meta-analysis revealed that, in patients with CRC, the BRAF mutation was associated with female, proximal site, poor differentiation, >5 cm size, and advanced AJCC stage.Conclusions:This meta-analysis demonstrated that BRAF mutation was closely related to adverse pathological features and poor outcome of CRC.

Automated PCR detection of BRAF mutations in colorectal adenocarcinoma: a diagnostic test accuracy study

BackgroundTesting for BRAF mutations in colorectal carcinoma (CRC) is important in the screening pathway for Lynch syndrome and is of prognostic value to guide management. This is a diagnostic accuracy...

Immunohistochemistry using the BRAF V600E mutation‐specific monoclonal antibody VE1 is not a useful surrogate for genotyping in colorectal adenocarcinoma

The presence of a BRAF mutation is a strong marker for poor prognosis of colorectal carcinoma (CRC), and can be used as evidence of a sporadic mechanism of mismatch repair deficiency. BRAF mutation may also predict resistance to EGFR-targeted therapy. A BRAF V600E-specific antibody has recently become commercially available. The aim of this study was to determine whether immunohistochemistry can predict BRAF mutations in CRC. Immunohistochemistry was performed on 52 genotyped CRC cases (17 BRAF mutant, 18 KRAS mutant, 17 BRAF/KRAS wild-type) with monoclonal antibody VE1. Cytoplasmic staining was observed in 71% of BRAF V600E mutant tumours (moderate or strong staining in 50% of these cases). Weak cytoplasmic staining was observed in 17% of KRAS mutant tumours and 35% of wild-type tumours. Non-specific nuclear staining was common. The sensitivity and specificity of immunohistochemistry with VE1 for BRAF mutation were 71% and 74%, respectively; when only moderate or strong staining was considered to be positive, the specificity was 100%, but the sensitivity only 35%. Immunohistochemistry with VE1 is not a useful surrogate for genotyping in CRC. Although moderate or strong cytoplasmic staining is specific for BRAF V600E mutations, this antibody is insufficiently sensitive to serve as an effective screening tool.

Molecular biomarker profile of EGFR copy number, KRAS and BRAF mutations in colorectal carcinoma

Anti-EGFR therapy is approved by US Food and Drug Administration (FDA) as mono-therapy or as part of combination chemotherapy for metastatic colorectal carcinoma. Monoclonal anti-EGFR antibodies cetuximab and panitumumab have shown benefits for those patients with wild-type KRAS gene. Patients with KRAS mutation in codon 12 or 13 are unresponsive to targeted anti-EGFR therapy. Mutations of BRAF, the main downstream target gene of KRAS, also negatively impact the patients’ response to the therapy. On the contrary, EGFR gene amplification in colon cancer predicts a better response to anti-EGFR therapy. The correlation of EGFR amplification with KRAS and BRAF mutation status is not only of academic interests but also of clinical importance. Previous studies have shown that EGFR mutation is mutually exclusive with KRAS and BRAF mutations in lung cancer. However, there is limited data on colorectal cancer so far. In this study, 28 colorectal cancer samples are tested for KRAS and BRAF mutations by PCR and for EGFR gene copy number by fluorescence in situ hybridization (FISH). EGFR high-copies, KRAS mutation and BRAF mutation are found in 15 (54%), 13 (46%) and 3 (11%) samples, respectively. A pattern is seen between KRAS mutations (13 positive samples) and BRAF mutations (3 positive samples). However, high EGFR high copy number is not mutually-exclusive with KRAS or BRAF mutations. Six samples with KRAS mutations and 2 with BRAF mutation show co-existing high EGFR copy number. These account for 29% of total cases tested. Five cases are triple negative for EGFR, KRAS and BRAF alterations. The results from our study indicate that high EGFR copy number with concurrent KRAS or BRAF mutations is quite common in colon cancer and the therapeutic response with anti-EGFR agents in this patient population requires further investigation.

Detection of KRAS and BRAF Mutations in Colorectal Carcinoma : Roles for High-Sensitivity Locked Nucleic Acid-PCR Sequencing and Broad-Spectrum Mass Spectrometry Genotyping

KRAS and BRAF mutations predict the resistance of colorectal carcinomas to therapy targeted to the epidermal growth factor receptor, but their detection can be challenging because of high testing volume, frequently low tumor content, and the spectrum of rarer mutations in these genes. To address these issues, we evaluated a locked nucleic acid (LNA)-PCR sequencing assay to detect low levels of mutant DNA, and we also evaluated a mass spectrometry genotyping assay (Sequenom, San Diego, CA) that is suitable for broad mutation screening. Clinical cases (n = 308) previously tested for KRAS and BRAF by standard sequencing were retested by LNA-PCR sequencing incorporating an LNA oligonucleotide to suppress amplification of nonmutant DNA, and by a Sequenom assay panel targeting common mutations in both genes. Standard sequencing detected 121 KRAS (39%) and 10 BRAF mutations; retesting with the LNA-based method and the Sequenom assay detected 19 (140/308, 45%) and 6 (127/308, 41%) additional KRAS mutants, respectively. One additional BRAF mutant was detected by the Sequenom assay. The analytical sensitivities were 0.3% for both KRAS and BRAF by LNA-PCR and from 1% to 10% for the Sequenom assays, depending on the specific mutation. Given these results, standard sequencing is suboptimal for mutation detection in metastatic and treated lesions even with predissection for tumor enrichment. High-sensitivity LNA-PCR sequencing detects significantly more mutations, whereas the Sequenom platform shows intermediate sensitivity but offers significant advantages for broader mutation screening.

BRAF mutations in colorectal carcinoma suggest two entities of microsatellite‐unstable tumors

BRAF mutations in colorectal carcinoma suggest two entities of microsatellite‐unstable tumors

BRAF mutations in colorectal carcinoma suggest two entities of microsatellite‐unstable tumors

Alterations of BRAF have been implicated in the carcinogenesis of colorectal tumors with microsatellite instability (MSI). These alterations were attributed to defective DNA mismatch repair, which underlies MSI. It was the objective of this study to clarify the role of BRAF in colorectal carcinoma with MSI. After sequencing for BRAF and KRAS in 82 colorectal tumor samples with or without MSI, mismatch repair protein expression was analyzed by immunohistochemistry, and promoter methylation of hMLH1 was analyzed with a methylation-specific polymerase chain reaction. Results were correlated with the germline status of hMLH1 or hMSH2 and clinical characteristics. BRAF was mutated more often in tumors with MSI than in tumors without MSI (27% vs. 5%; P = 0.016). The most prevalent BRAF alteration, V599E, occurred only in tumors with MSI. BRAF V599E was associated with more frequent hMLH1 promoter methylation (P = 0.07) and loss of hMLH1 (P = 0.02). The median age of patients with BRAF V599E was older compared with the median age of patients without this mutation (P = 0.001; 78 vs. 49 yrs). No BRAF alterations occurred in patients with germline mutations of mismatch repair genes. Five novel BRAF mutations were identified. Although BRAF V599E was common in colorectal carcinomas with MSI, it was not a consequence of deficient mismatch repair. The current data showed instead that the BRAF V599E mutation was associated only with a subgroup of colorectal carcinomas with MSI that were obtained from older patients without hereditary nonpolyposis colorectal carcinoma and showed epigenetic silencing of hMLH1. These results indicated that tumors with MSI caused by epigenetic MLH1 silencing have a distinct mutational background from that of tumors with genetic loss of mismatch repair, suggesting that there are two genetically distinct entities of microsatellite-instable tumors.