Predictive and prognostic roles of BRAF mutation in stage III colon cancer: results from intergroup trial CALGB 89803

Evaluating the utility of ZNF331 promoter methylation as a prognostic and predictive marker in stage III colon cancer: results from CALGB 89803 (Alliance)

While epigenomic alterations are common in colorectal cancers (CRC), few epigenomic biomarkers that risk-stratify patients have been identified. We thus sought to determine the potential of ZNF331 promoter hypermethylation (mZNF331) as a prognostic and predictive marker in colon cancer. We examined the association of mZNF331 with clinicopathologic features, relapse, survival, and treatment efficacy in patients with stage III colon cancer treated within a randomized adjuvant chemotherapy trial (CALGB/Alliance89803). Residual tumour tissue was available for genomic DNA extraction and methylation analysis for 385 patients. ZNF331 promoter methylation status was determined by bisulphite conversion and fluorescence-based real-time polymerase chain reaction. Kaplan-Meier estimator and Cox proportional hazard models were used to assess the prognostic and predictive role of mZNF331 in this well-annotated dataset, adjusting for clinicopathologic features and standard molecular markers. mZNF331 was observed in 267/385 (69.4%) evaluable cases. Histopathologic features were largely similar between patients with mZNF331 compared to unmethylated ZNF331 (unmZNFF31). There was no significant difference in disease-free or overall survival between patients with mZNF331 versus unmZNF331 colon cancers, even when adjusting for clinicopathologic features and molecular marker status. Similarly, there was no difference in disease-free or overall survival across treatment arms when stratified by ZNF331 methylation status. While ZNF331 promoter hypermethylation is frequently observed in CRC, our current study of a small subset of patients with stage III colon cancer suggests limited applicability as a prognostic marker. Larger studies may provide more insight and clarity into the applicability of mZNF331 as a prognostic and predictive marker.

BRAF + EGFR +/- MEK inhibitors after immune checkpoint inhibitors in BRAF V600E mutated and deficient mismatch repair or microsatellite instability high metastatic colorectal cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs) are the guideline endorsed first choice for patients with deficient mismatch repair or microsatellite instability high (dMMR/MSI-H) mCRC, however a significant proportion experience primary or secondary resistance. BRAF V600E mutated (BRAFm) and dMMR/MSI-H mCRC can be treated with BRAF + EGFR inhibitors but specific data on the efficacy after progression to ICIs are missing.

METHODS

We collected consecutive patients with BRAFm dMMR/MSI-H mCRC treated from 2017 to 2024 with a combination of BRAFi+EGFRi+/-MEKi, after disease progression on ICIs. A control cohort of BRAFm pMMR/MSS mCRC patients treated with encorafenib+cetuximab+/-binimetinib from 2nd line was used.

RESULTS

dMMR/MSI-H (n = 50) BRAFm mCRC patients were more often > 70-year-old, with right-sided primary tumors, without liver but more lymphnode metastases than pMMR/MSS (n = 170). They were treated more frequently beyond 2nd line and 45 % were primary progressors to ICIs. Lower ORR (18 % versus 32 %, p = 0.09) and DCR (60 % versus 73 %, p = 0.11) was seen without reaching significance in dMMR/MSI-H as compared to pMMR/MSS patients. After a median follow-up of 14.04 months, no differences in PFS (median 5.13 versus 4.50 months, HR 0.83, 95 %CI: 0.57-1.20, p = 0.31) and OS (median 10.75 versus 9.11 months, HR 0.89, 95 %CI: 0.59-1.32, p = 0.55) were observed.

CONCLUSIONS

Our results show that BRAFm dMMR/MSI-H mCRC patients benefit from BRAFi+EGFRi+/-MEKi after progression under ICIs. Despite lower ORR and DCR, the outcome is not different from that observed in pMMR/MSS BRAFm CRC and is in line with the results of the BEACON registration trial.

Tretinoin synergistically enhances the antitumor effect of combined BRAF, MEK, and EGFR inhibition in BRAFV600E colorectal cancer

Patients with BRAF-mutated colorectal cancer (BRAFV600E CRC) are currently treated with a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor. A fundamental problem in treating patients with BRAFV600E CRC is intrinsic and/or acquired resistance to this combination therapy. By screening 78 compounds, we identified tretinoin, a retinoid, as a compound that synergistically enhances the antiproliferative effect of a combination of BRAF inhibition and MEK inhibition with or without EGFR inhibition on BRAFV600E CRC cells. This synergistic effect was also exerted by other retinoids. Tretinoin, added to BRAF inhibitor and MEK inhibitor, upregulated PARP, BAK, and p-H2AX. When either RARα or RXRα was silenced, the increase in cleaved PARP expression by the addition of TRE to ENC/BIN or ENC/BIN/CET was canceled. Our results suggest that the mechanism of the synergistic antiproliferative effect involves modulation of the Bcl-2 family and the DNA damage response that affects apoptotic pathways, and this synergistic effect is induced by RARα- or RXRα-mediated apoptosis. Tretinoin also enhanced the antitumor effect of a combination of the BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor in a BRAFV600E CRC xenograft mouse model. Our data provide a rationale for developing retinoids as a new combination agent to overcome resistance to the combination therapy for patients with BRAFV600E CRC.

Single-Cell Profiling Reveals the Impact of Genetic Alterations on the Differentiation of Inflammation-Induced Murine Colon Tumors

Genetic mutations and chronic inflammation of the colon contribute to the development of colorectal cancer (CRC). Using a murine model of inflammation-induced colon tumorigenesis, we determined how genetic mutations alter colon tumor cell differentiation. Inflammation induced by enterotoxigenic Bacteroides fragilis (ETBF) colonization of multiple intestinal neoplasia (MinApcΔ716/+) mice triggers loss of heterozygosity of Apc causing colon tumor formation. Here, we report that the addition of BRAFV600E mutation (BRAFF-V600ELgr5tm1(Cre/ERT2)CleMinApcΔ716/+, BLM) or knocking out Msh2 (Msh2LoxP/LoxPVil1-creMinApcΔ716/+, MSH2KO) in the Min model altered colon tumor differentiation. Using single-cell RNA sequencing, we uncovered the differences between BLM, Min, and MSH2KO tumors at a single-cell resolution. BLM tumors showed an increase in differentiated tumor epithelial cell lineages and a reduction in the tumor stem cell population. Interestingly, the tumor stem cell population of BLM tumors had revival colon stem cell characteristics with low WNT signaling and an increase in RevCSC marker gene expression. In contrast, MSH2KO tumors were characterized by an increased tumor stem cell population that had higher WNT signaling activity compared to Min tumors. Furthermore, overall BLM tumors had higher expression of transcription factors that drive differentiation, such as Cdx2, than Min tumors. Using RNA velocity, we identified additional potential regulators of BLM tumor differentiation such as NDRG1. The role of CDX2 and NDRG1 as putative regulators for BLM tumor cell differentiation was verified using organoids derived from BLM tumors. Our results demonstrate the critical connections between genetic mutations and cell differentiation in inflammation-induced colon tumorigenesis. Understanding such roles will deepen our understanding of inflammation-associated colon cancer.

RAS/RAF/MAPK Pathway Mutations as Predictive Biomarkers in Middle Eastern Colorectal Cancer: A Systematic Review

Background

This review article aims to investigate the prevalence and spectrum of rat sarcoma (RAS) and V-Raf Murine Sarcoma Viral Oncogene Homolog B (BRAF) mutations, and their connection with geographical location, clinicopathological features, and other relevant factors in colorectal cancer (CRC) patients in the Middle East.

Methods

A systematic literature review, employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, was conducted to investigate the association between the frequency of relevant mutations and the descriptive clinicopathological characteristics of CRC patients. Multiple electronic databases, including PubMed, Science Direct, Web of Science, Scopus, and Google Scholar, were searched to analyze the relevant literature.

Results

A total of 19 eligible studies comprising 2960 patients with CRC were included in this review. A comprehensive analysis of the collected literature data as well as descriptive and methodological insights is provided. Men were predominant in reviewed studies for the region, accounting for 58.6%. Overall, RAS mutation prevalence was 38.1%. Kirsten RAS Viral Oncogene Homolog (KRAS) mutations were the most common, accounting for 37.1% of cases and distributed among different exons, with the G12D mutation being the most frequent in exon 2 (23.2%) followed by G12V (13.7%), G13D (10.1%), G12C (5.1%), G12A (5.04%), and G12S (3.6%). Neuroblastoma RAS Viral Oncogene Homolog (NRAS) mutations were identified in 3.3% of tumor samples, with the most common mutation site located in exons 2, 3, and 4, and codon 61 being the most common location for the region. The total mutation frequency in the BRAF gene was 2.6%, with the V600E mutation being the most common.

Conclusion

The distribution patterns of RAS and BRAF mutations among CRC patients exhibit notable variations across diverse ethnic groups. Our study sheds light on this phenomenon by demonstrating a higher prevalence of KRAS mutations in CRC patients from the Middle East, as compared with those from other regions. The identification of these mutations and geographical differences is important for personalized treatment planning and could potentially aid in the development of novel targeted therapies. The distinct distribution patterns of RAS and BRAF mutations among CRC patients across different ethnic groups, as well as the regional variability in mutation prevalence, highlight the need for further research in this area.

Unraveling the Interplay of KRAS, NRAS, BRAF, and Micro-Satellite Instability in Non-Metastatic Colon Cancer: A Systematic Review

Microsatellite Instability (MSI-H) occurs in approximately 15% of non-metastatic colon cancers, influencing patient outcomes positively compared to microsatellite stable (MSS) cancers. This systematic review focuses on the prognostic significance of KRAS, NRAS, and BRAF mutations within MSI-H colon cancer. Through comprehensive searches in databases like MEDLINE, EMBASE, and others until 1 January 2024, we selected 8 pertinent studies from an initial pool of 1918. These studies, encompassing nine trials and five observational studies involving 13,273 patients, provided insights into disease-free survival (DFS), survival after recurrence, and overall survival. The pooled data suggest that while KRAS and BRAF mutations typically predict poorer outcomes in MSS colorectal cancer, their impact is less pronounced in MSI contexts, with implications varying across different stages of cancer and treatment responses. In particular, adverse effects of these mutations manifest significantly upon recurrence rather than affecting immediate DFS. Our findings confirm the complex interplay between genetic mutations and MSI status, emphasizing the nuanced role of MSI in modifying the prognostic implications of KRAS, NRAS, and BRAF mutations in colon cancer. This review underscores the importance of considering MSI alongside mutational status in the clinical decision-making process, aiming to tailor therapeutic strategies more effectively for colon cancer patients.

Efficacy and safety of natural killer cells injection combined with XELOX chemotherapy in postoperative patients with stage III colorectal cancer in China: a prospective randomised controlled clinical trial study protocol

BACKGROUND

Colorectal cancer (CRC) is the second most frequently diagnosed cancer and the fifth leading cause of cancer-related death in China. However, resistance to multiple chemotherapeutics after surgery leads to failure of the main therapy to CRC. Natural killer (NK) cells are innate cytotoxic lymphocytes that exhibit strong cytotoxic activity against tumour cells. NK cell-based therapy, either alone or in combination with chemotherapy, has achieved favourable results and holds promise for addressing recurrence and metastasis in CRC patients after surgery.

METHODS AND ANALYSIS

This is a prospective, randomised controlled clinical trial to evaluate efficacy and safety of interleukin 2 activated NK cells injection combined with XELOX (capecitabine plus oxaliplatin)-based chemotherapy for postoperative CRC patients. Participants will be randomly divided into treatment group and control group, and every group includes 40 patients. The treatment group will also receive NK cells (5×109) with+XELOX-based chemotherapy, while the control group will receive only XELOX-based chemotherapy. This treatment will be repeated for eight cycles (6 months). The follow-up period lasts about 3 years, during which CEA, CA19-9, CA125, enhancement CT and colonoscopy will be conducted. The primary endpoints of this study are progression-free survival and overall survival, while the secondary endpoint is safety (number and severity of adverse events). Additionally, we aim to identify cancer stem cells in peripheral blood and predictive biomarkers (cytokines secreted by NK cells and activated markers of NK cells) that indicate patients who achieve an effective response.

ETHICS AND DISSEMINATION

The study has been approved by the Clinical Research Ethics Committee of our hospital (approval number 2023LLSC006) and the Chinese Clinical Trials. It will be conducted in accordance with the Declaration of Helsinki. Written informed consent will be obtained from all participants. The study findings will be submitted to peer-reviewed journals for publication.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trials Registry (ChiCTR2300075861).

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

KRAS and BRAF Mutation Rates and Survival Outcomes in Colorectal Cancer in an Ethnically Diverse Patient Cohort

KRAS and BRAF mutation rates in colorectal cancer (CRC) reported from various mono-ethnic studies vary amongst different ethnic groups. However, these differences in mutation rates may not be statistically significant or may be due to differences in environmental and/or laboratory factors across countries rather than racial genetic differences. Here, we compare the KRAS/BRAF mutation rates and survival outcomes in CRC between ethnic groups at a single institution. We also investigate the contributions of genetic, environmental, and laboratory factors to the variations in KRAS/BRAF mutation rates reported from different countries. Clinicopathological data from 453 ethnically diverse patients with CRC were retrospectively analyzed at Liverpool Hospital, NSW Australia (2014-2016). KRAS/BRAF mutations were detected using real-time PCR (Therascreen kits from Qiagen). Mismatch repair (MMR) status was determined using immunohistochemical staining. Four ethnic groups were analyzed: Caucasian, Middle Eastern, Asian, and South American. Overall survival data were available for 406 patients. There was no significant difference in KRAS mutation rates between Caucasians (41.1%), Middle Easterners (47.9%), Asians (44.8%), and South Americans (25%) (p = 0.34). BRAF mutation rates differed significantly between races (p = 0.025), with Caucasians having the highest rates (13.5%) and Middle Easterners the lowest (0%). A secondary analysis in which Caucasians were divided into three subgroups showed that ethnic grouping correlated significantly with KRAS mutation rate (p = 0.009), with central and eastern Europeans having the highest rates (58.3%). There were no significant differences in overall survival (OS) or disease-free survival (DFS) between the four races. The similarity in KRAS mutation rates across races raises the possibility that the differences in KRAS mutation rates reported from various countries may either not be statistically significant or may be due to environmental and/or laboratory factors rather than underlying racial genetic differences. In contrast, we verified that BRAF mutation rates differ significantly between races, suggesting racial genetic differences may be responsible for the discrepant BRAF mutation rates reported from different countries.

Different prognostic values of KRAS exon 2 submutations and BRAF V600E mutation in microsatellite stable (MSS) and unstable (MSI) stage III colon cancer: an ACCENT/IDEA pooled analysis of seven trials

BACKGROUND

The prognostic value of KRAS and BRAFV600E mutations in stage III colon cancer (CC) remains controversial and has never been clearly analyzed in patients with microsatellite instability-high (MSI-H) tumors due to sample size limitations. Data are also lacking for KRAS submutations and prognosis.

PATIENTS AND METHODS

We examined clinicopathological variables and prognosis in patients with surgically resected stage III CC who participated in seven clinical trials from the ACCENT/IDEA databases. Associations between KRAS exon 2 and BRAFV600E mutations and time to recurrence (TTR), overall survival (OS), and survival after recurrence (SAR) were assessed using a Cox model. We also analyzed the prognostic value of KRAS exon 2 submutations.

RESULTS

Among 8460 patients, 11.4% had MSI-H status. In the MSI-H group, BRAFV600E, KRAS exon 2 mutants, and double-wild-type statuses were detected in 40.6%, 18.1%, and 41.3%, respectively, whereas and in the microsatellite stable (MSS) group, these were detected in 7.7%, 38.6%, and 53.8%, respectively. In the MSS group, 5-year TTR rates of 61.8%, 66.3%, and 72.9% were observed among patients with BRAFV600E, KRAS exon 2 mutants, and those who were DWT, respectively [adjusted hazard ratio (HR) = 1.58 and 1.31, both P < 0.001]. In the MSI-H group, 5-year TTR rates did not differ significantly among the mutated subgroups. Similar results were found for OS. However, survival after relapse was significantly shorter in the KRAS exon 2- and BRAFV600E-mutated patients in both MSS (adjusted HR = 2.06 and 1.15; both P < 0.05) and MSI-H (adjusted HR = 1.99 and 1.81; both P < 0.05) groups. In the MSS group, KRAS exon 2 mutations were associated with TTR, but only p.G12C, p.G12D, and p.G13D were associated with poor outcomes after disease recurrence.

CONCLUSIONS

Testing for both KRAS and BRAFV600E mutations in stage III patients should be considered as they can better define individual patient prognosis, and may also enable patient selection for (neo)adjuvant trials dedicated to specific molecular subtypes with poor prognosis.

Pin1 inhibitor API-1 sensitizes BRAF-mutant thyroid cancers to BRAF inhibitors by attenuating HER3-mediated feedback activation of MAPK/ERK and PI3K/AKT pathways

BRAFV600E mutation is one of the most therapeutic targets in thyroid cancers. However, its specific inhibitors have shown little clinical benefit because they can reactivate the MAPK/ERK and PI3K/AKT pathways by feedback upregulating the transcription of HER3. Peptidyl-prolyl cis/trans isomerase Pin1 has been proven to be closely associated with tumor progression. Here, we aimed to determine antitumor activity of Pin1 inhibitor API-1 in thyroid cancer and its effect on cellular response to BRAF inhibitors. The results showed that API-1 exhibited strong antitumor activity against thyroid cancer. Meanwhile, it improved the response of BRAF-mutant thyroid cancer cells to BRAF inhibitor PLX4032 and there was a synergistic effect between them. Specially, a combination therapy of API-1 and PLX4032 significantly inhibited cell proliferation, colony formation, and the growth of xenograft tumors as well as induced cell apoptosis in BRAF-mutant thyroid cancer cells compared with API-1 or PLX4032 monotherapy. Similar results were also observed in transgenic mice with BrafV600E-driven thyroid cancer. Mechanistically, API-1 enhanced XPO5 ability to export pre-microRNA 20a (pre-miR-20a) from the nucleus to cytoplasm, thereby promoting the maturation of miR-20a-5p. Further studies showed that miR-20a-5p specifically targeted and down-regulated HER3, thereby blocking the reactivation of MAPK/ERK and PI3K/AKT signaling pathways caused by PLX4032. These results, taken together, demonstrate that Pin1 inhibitor API-1 significantly improves the sensitivity of BRAF-mutant thyroid cancer cells to PLX4032. Thus, this study not only determines the potential antitumor activity of Pin1 inhibitor API-1 in thyroid cancer but also offers an alternative therapeutic strategy for BRAF-mutant thyroid cancers by a combination of Pin1 inhibitor and BRAF kinase inhibitor.

Cuproptosis-related risk score predicts prognosis and characterizes the tumor microenvironment in colon adenocarcinoma

Introduction

Cuproptosis is a novel copper-dependent regulatory cell death (RCD), which is closely related to the occurrence and development of multiple cancers. However, the potential role of cuproptosis-related genes (CRGs) in the tumor microenvironment (TME) of colon adenocarcinoma (COAD) remains unclear.

Methods

Transcriptome, somatic mutation, somatic copy number alteration and the corresponding clinicopathological data of COAD were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus database (GEO). Difference, survival and correlation analyses were conducted to evaluate the characteristics of CRGs in COAD patients. Consensus unsupervised clustering analysis of CRGs expression profile was used to classify patients into different cuproptosis molecular and gene subtypes. TME characteristics of different molecular subtypes were investigated by using Gene set variation analysis (GSVA) and single sample gene set enrichment analysis (ssGSEA). Next, CRG Risk scoring system was constructed by applying logistic least absolute shrinkage and selection operator (LASSO) cox regression analysis and multivariate cox analysis. Real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC) were used to exam the expression of key Risk scoring genes.

Results

Our study indicated that CRGs had relatively common genetic and transcriptional variations in COAD tissues. We identified three cuproptosis molecular subtypes and three gene subtypes based on CRGs expression profile and prognostic differentially expressed genes (DEGs) expression profile, and found that changes in multilayer CRGs were closely related to the clinical characteristics, overall survival (OS), different signaling pathways, and immune cell infiltration of TME. CRG Risk scoring system was constructed according to the expression of 7 key cuproptosis-related risk genes (GLS, NOX1, HOXC6, TNNT1, GLS, HOXC6 and PLA2G12B). RT-qPCR and IHC indicated that the expression of GLS, NOX1, HOXC6, TNNT1 and PLA2G12B were up-regulated in tumor tissues, compared with those in normal tissues, and all of GLS, HOXC6, NOX1 and PLA2G12B were closely related with patient survival. In addition, high CRG risk scores were significantly associated with high microsatellite instability (MSI-H), tumor mutation burden (TMB), cancer stem cell (CSC) indices, stromal and immune scores in TME, drug susceptibility, as well as patient survival. Finally, a highly accurate nomogram was constructed to promote the clinical application of the CRG Risk scoring system.

Discussion

Our comprehensive analysis showed that CRGs were greatly associated with TME, clinicopathological characteristics, and prognosis of patient with COAD. These findings may promote our understanding of CRGs in COAD, providing new insights for physicians to predict prognosis and develop more precise and individualized therapy strategies.

Evaluation of methylated DCR1 as a biomarker for response to adjuvant irinotecan-based therapy in stage III colon cancer: cancer and leukaemia Group B 89803 (Alliance)

Aberrantly methylated genes contribute to the landscape of epigenetic alterations in colorectal adenocarcinoma. The global CpG Island methylator phenotype (CIMP) and individually methylated genes are potential prognostic/predictive biomarkers. Research suggests an association between methylated DCR1 (mDCR1) and lack of benefit with irinotecan (IFL) treatment. We assessed the association between DCR1 methylation status and survival in patients receiving adjuvant fluorouracil/ leucovorin (5-FU/LV) or IFL. We analysed data from patients with stage III colon adenocarcinoma randomly assigned to adjuvant 5-FU/LV or IFL in CALGB 89803 (Alliance). The primary endpoint was overall survival (OS), and the secondary endpoint was disease-free survival (DFS). Using tumour sample DNA, we evaluated the association between survival, DCR1 methylation status, and molecular subgroups (BRAF, KRAS, mismatch repair status, CIMP status) using Kaplan-Meier estimator and Cox proportional hazard model. mDCR1 was observed in 221/400 (55%) colon cancers. Histopathologic features were similar between mDCR1 and unmethylated DCR1 (unDCR1) colon cancers. There was no difference in OS (p = 0.83) or DFS (p = 0.85) based on DCR1 methylation status. There was no association between methylation status and response to IFL . In patients with unDCR1 and KRAS-wildtype tumours, those who received IFL had a nearly two-fold worse DFS compared to patients who received 5-FU/LV (HR = 1.85, 95% CI (0.97-3.53, p = 0.06). This relationship was not notable among other subgroups. In stage III colon cancer patients, mDCR1 status did not associate with response to irinotecan. Larger studies may suggest an association between the iridocene response and molecular subgroups.

KRAS, NRAS, BRAF, PIK3CA, and AKT1 signatures in colorectal cancer patients in south-eastern Romania

Somatic mutations in the oncogenes of the epidermal growth factor receptor signaling pathway play vital roles in colorectal carcinogenesis and have been closely linked with clinical resistance to monoclonal therapy. In this study, we have analyzed the mutation frequencies of 5 genes and compared the genetic findings with clinicopathological variables in order to determine diagnostically relevant alterations and compare these findings with those of other studies In our Sanger sequencings, KRAS (exons 2, 3, and 4), NRAS (exons 2, 3, and 4), PIK3CA (exons 9 and 20), BRAF (exon 15), AKT1 (exon 2) genes, and microsatellite instability (MSI) status were analyzed using an ABI 3500 analyzer in a cohort of 58 Romanian colorectal cancer (CRC) patients who underwent surgical resection at Emergency County Clinical Hospital in Constanța, Romania. In our series, mutation rates of KRAS, BRAF, PIK3CA, and AKT1 genes were 39.63%, 8.62%, 6.88%, and 3.44%, respectively. By contrast, we did not find any tumor harboring mutation in the NRAS gene. Notably, the KRAS and PIK3CA mutations were not mutually exclusive, 1 patient harbored 2 mutations in exon2, codon 12 (Gly12Val) of KRAS and exon 20, codon 1047 (His1047Arg) of PIK3CA. The finding of our study are generally consistent with data found in the literature. Regarding to clinicopathological variables, mutation of KRAS was associated with distant metastasis at the time of diagnosis, while mutation of BRAF was significantly associated with MSI-H in contrast with MSI-L/MSS tumors. Moreover, PIK3CA mutation tends to be located in the proximal segment of the colon and to be well/moderately differentiated compared to wild-type tumors. In conclusion, the assessment of these mutations suggests that CRC patients from southeast Romania exhibit a mutation profile similar to other populations. These results could contribute to creating a better method of qualifying patients for molecularly targeted therapies and obtaining better screening strategies.

BRAF Mutations in Colorectal Liver Metastases: Prognostic Implications and Potential Therapeutic Strategies

Simple Summary

In this literature review, we investigated the relationship between BRAF mutation and prognosis in patients with colorectal cancer liver metastases. We also investigated factors affecting the prognosis of patients with BRAF mutations and summarized the latest research on targeted therapies.

Abstract

Surgery combined with chemotherapy and precision medicine is the only potential treatment for patients with colorectal cancer liver metastases (CRLM). The use of modern molecular biotechnology to identify suitable biomarkers is of great significance for predicting prognosis and formulating individualized treatment plans for these patients. BRAF mutations, particularly V600E, are widely believed to be associated with poor prognosis in patients with metastatic CRC (mCRC). However, it is unclear which specific factors affect the prognosis of CRLM patients with BRAF mutations. It is also unknown whether patients with resectable CRLM and BRAF mutations should undergo surgical treatment since there is an increased recurrence rate after surgery in these patients. In this review, we combined the molecular mechanism and clinical characteristics of BRAF mutations to explore the prognostic significance and potential targeted therapy strategies for patients with BRAF-mutated CRLM.

Microsatellite instability and chemosensitivity in solid tumours

The use of biomarkers that influence a targeted choice in cancer treatments is the future of medical oncology. Within this scenario, in recent years, an important role has been played by knowledge of microsatellite instability (MSI), a molecular fingerprint that identifies defects in the mismatch repair system. This knowledge has changed clinical practice in the adjuvant setting of colon cancer, and its role in the neoadjuvant setting in gastric tumours is becoming increasingly interesting, as well as in endometrial cancers in both early and advanced diseases. Furthermore, it has undoubtedly conditioned the first lines of treatment in the metastatic setting in different types of cancers. The incidence of MSI is different in different cancer types, as well as in early cancers versus metastatic disease. Knowing the incidence of MSI in the various histologies can provide insight into the potential use of this biomarker considering its prognostic value, especially in the early stages, and its predictive role with respect to treatment response. In particular, MSI can guide the choice of chemotherapy treatments in the adjuvant setting of colon and perioperative setting in gastric tumours, which could lead to immunotherapy treatments in these patients in both the early stages of the disease and the metastatic setting where the response to immunotherapy drugs in diseases with MSI is now well established. In this review, we focus on colon, gastric and endometrial cancers, and we briefly discuss other cancer types where MSI could have a potential role in oncological treatment decisions.

Survival benefit with adjuvant chemotherapy in stage III microsatellite-high/deficient mismatch repair colon cancer: a systematic review and meta-analysis

Clinical observations have demonstrated that microsatellite instability-high (MSI-H) and/or deficient MMR (dMMR) status are associated with favorable prognosis and no benefit from 5-Fluorouracil (5-FU)-based adjuvant chemotherapy in patients with resected stage II colorectal cancer (CRC). This study represents a systematic review and meta-analysis exploring the predictive role of MSI-H status in stage III CRC undergoing or not adjuvant chemotherapy. Published articles that evaluated the role of adjuvant chemotherapy in resected stage III CRC from inception to September 2020 were identified by searching the PubMed, EMBASE, and Cochrane Library databases. The random-effects model was conducted to estimate the pooled effect size of OS and DFS. The primary outcome of interest was OS. 21,590 patients with MSI-H/dMMR stage III CRC, from n = 17 retrospective studies, were analyzed. Overall, OS was improved with any adjuvant chemotherapy vs. any control arm (single-agent 5-FU or surgery alone): HR 0.42, 95% CI 0.26–0.66; P < 0.01. Conversely, DFS was not significantly improved (HR 0.7, 95% CI 0.45–1.09; P = 0.11). In patients with stage III MSI-H/dMMR CRC, adjuvant chemotherapy is associated with a significant OS improvement. Thus, MSI-H/dMMR status does represent a predictive factor for postoperative chemotherapy benefit in stage III CRC beyond its prognostic role.

Sustainable Clinical Development of Adjuvant Chemotherapy for Colon Cancer

Numerous clinical studies in an adjuvant setting have been conducted and the combination therapy of 5-fluorouracil and oxaliplatin has been established as the standard treatment for Stage III and as an option for high-risk Stage II patients. Biologics such as bevacizumab and antiepidermal growth factor receptor antibodies have failed to show additional survival benefits. The indication of adjuvant chemotherapy has been determined according to the pathological stage. Nevertheless, a pathological diagnosis does not necessarily result in selection of the optimal treatment. To improve treatment decisions, many trials have aimed to stratify patients into treatment groups using genomic testing. Recently, gene signature, Immunoscore, and circulating tumor DNA (ctDNA) assays have been reported and among them, ctDNA was shown to be a promising accurate predictive marker for recurrence. Treatment of ctDNA-positive patients with aggressive chemotherapy may reduce recurrence rates. The ultimate goal is to accurately predict the risk of recurrence and to prevent recurrence in colon cancer patients. In this review we focus on the clinical development of adjuvant chemotherapy and stratification of patients according to risk of recurrence and the future direction of adjuvant chemotherapy.

BRAF mutation status and its prognostic significance in 79 canine urothelial carcinomas: A retrospective study (2006-2019)

Urothelial carcinoma (UC) is the most common tumour of the canine urinary bladder. Recently, BRAF mutation testing emerged as a diagnostic option, but its prognostic significance is unknown. This study investigates the relationship between BRAF (variant V595E) mutation status and overall survival in UC-bearing dogs. Seventy-nine patients histologically diagnosed with UC of the bladder and/or urethra between 2006 and 2019 were included in this retrospective single-centre-study. Treatment consisted of meloxicam (n = 39, group 1 'Melox'), mitoxantrone and meloxicam (+/- followed by metronomic chlorambucil; n = 23, group 2 'Chemo') or partial cystectomy followed by meloxicam +/- mitoxantrone (n = 17, group 3 'Sx'). Survival was significantly influenced by treatment (p = .0002) and tumour location (p < .001) in both uni- and multivariable analyses. BRAF mutation was identified in 51 tumours (=64.6%) and had no statistically significant influence on overall survival: MST for BRAF-negative patients 359 versus 214 days for BRAF-positive dogs (p = .055). However, in BRAF-positive dogs, survival depended significantly on type of treatment in univariable analysis: MSTs for groups 1-3 were 151, 244 and 853 days, respectively (p = .006); In BRAF-positive group 2 ('Chemo')-patients, adjuvant metronomic chlorambucil after mitoxantrone more than doubled MST compared to patients receiving mitoxantrone alone (588 vs. 216 days; p = .030). In contrast, MSTs were not significantly different in BRAF-negative patients among the three treatment groups (p = .069). Multivariate analysis of these data was not possible due to group size limitations. This study identified tumour location and treatment type, but not BRAF mutation status, as independent prognostic factors for overall survival.

Mismatch Repair Status in Patient-Derived Colorectal Cancer Organoids Does Not Affect Intrinsic Tumor Cell Sensitivity to Systemic Therapy

DNA mismatch repair deficiency (dMMR) in metastatic colorectal cancer (mCRC) is associated with poor survival and a poor response to systemic treatment. However, it is unclear whether dMMR results in a tumor cell-intrinsic state of treatment resistance, or whether alternative mechanisms play a role. To address this, we generated a cohort of MMR-proficient and -deficient Patient-Derived Organoids (PDOs) and tested their response to commonly used drugs in the treatment of mCRC, including 5-fluorouracil (5-FU), oxaliplatin, SN-38, binimetinib, encorafenib, and cetuximab. MMR status did not correlate with the response of PDOs to any of the drugs tested. In contrast, the presence of activating mutations in the KRAS and BRAF oncogenes was significantly associated with resistance to chemotherapy and sensitivity to drugs targeting oncogene-activated pathways. We conclude that mutant KRAS and BRAF impact the intrinsic sensitivity of tumor cells to chemotherapy and targeted therapy. By contrast, tumor cell-extrinsic mechanisms-for instance signals derived from the microenvironment-must underlie the association of MMR status with therapy response. Future drug screens on rationally chosen cohorts of PDOs have great potential in developing tailored therapies for specific CRC subtypes including, but not restricted to, those defined by BRAF/KRAS and MMR status.

Early age of onset is an independent predictor for worse disease-free survival in sporadic rectal cancer patients. A comparative analysis of 980 consecutive patients

BACKGROUND

while interest on early-onset colorectal cancer (age ≤49) is on the rise, studies on early-onset rectal cancer (EORC) are limited. The aim of this study was to compare predictors for disease progression/recurrence between sporadic EORC and late-onset RC patients (LORC).

METHODS

163 EORC and 830 LORC operated between January 1st^, 2010 and April 30th^, 2021 at a tertiary center were included. Demographics, tumor characteristics, microsatellite status, gene mutations (KRAS, BRAF, NRAS, PI3Kca) and oncologic outcomes were compared. A Cox proportional hazards regression analysis was performed to ascertain the effect of variables on recurrence/progression and death. Recurrence/Progression free survival (R/PFS) and cancer specific survival (CSS) were analyzed by the Kaplan-Meier estimator.

RESULTS

Mean age of EORC was 42.16, (46% aged 45-49). A majority of EORC patients had a family history for CRC (p = 0.01) and underwent total neoadjuvant treatment (p = 0.01). EORC patients showed a higher rate of low-grade tumor differentiation (p < 0.0001), stage III-IV (p = 0.001), microsatellite instability (p = 0.02), locoregional nodal (p = 0.001) and distant metastases (p < 0.0001). Accordingly, more EORC patients underwent adjuvant treatment (p < 0.0001). Mutations were mostly reported among LORC cases (p = 0.04), whereas EORC patients showed a worse R/PFS (p = 0.02), even at stage I (p = 0.04). CSS did not differ (p = 0.11) across groups. Multivariate analysis indicated age of onset (p = 0.04) was an independent predictor for progression/recurrence.

CONCLUSIONS

Age of onset was shown to be an independent unfavorable predictor. Delayed diagnosis could explain this effect in the more advanced stages, while the worse outcomes in stage I may suggest a more aggressive disease behavior.

Impact of Relative Dose Intensity of FOLFOX Adjuvant Chemotherapy on Risk of Death Among Stage III Colon Cancer Patients

BACKGROUND

The National Comprehensive Cancer Network (NCCN) guidelines have recommended tailored chemotherapy for stage III high-risk (T4 and/or N2) and low-risk (T1-T3 and N1) colon cancer since 2018. Studies have investigated the effect of relative dose intensity (RDI) of FOLFOX on stage III colon cancer survival, however, none has performed a stratified analysis by risk profiles. This study aims to identify the FOLFOX optimal RDI for high-risk and low-risk stage III colon cancer patients.

METHODS

Data on 407 eligible patients, diagnosed with stage III colon cancer in 2011 who received FOLFOX, were collected by 8 population-based cancer registries. Multivariable Cox model and Fine-Gray competing risks model were employed to explore Optimal RDI defined as the lowest RDI administered without significant differences in either overall or cause-specific death.

RESULTS

Among the 168 high-risk patients, the optimal RDI cut-off was 70% (HR = 1.59 with 95% CI: 0.69-3.66 in overall mortality; HR = 1.24 with 95% CI: 0.42-3.64 in cause-specific mortality when RDI < 70% vs. RDI ≥ 70%). Among the 239 low-risk patients, none of the evaluated cut-offs were associated with significant differences in risk of death between comparison groups. The lowest assessed RDI was 45%, HR = 0.80; 95% CI: 0.24 to 2.73 for overall mortality and HR = 0.53; 95% CI: 0.06 to 4.95 for cause-specific mortality, when RDI <45% versus RDI ≥45%.

CONCLUSIONS

There is no significant harm on the risk of death when reducing RDI by <30% for high-risk patients. For the low-risk patients, we found that RDI as low as 45% did not significantly affect the risk of death.

Medullary Carcinoma of the Gastrointestinal Tract: Report on Two Cases with Immunohistochemical and Molecular Features

Medullary carcinoma of the colon is a rare histological variant characterized by a poorly differentiated morphology, an aberrant immunophenotype, and microsatellite instability. Despite the lack of glandular differentiation, medullary carcinoma is reported to have a good prognosis. It is typically located in the right colon and frequently affects older women. Due to its clinical, histological, biological, and genetic peculiarity, medullary carcinoma requires an accurate diagnosis and the awareness of this diagnostic possibility. We describe the morphological, immunohistochemical, and molecular findings of two interesting cases, the first one in the right colon of a patient and the second one in the terminal ileum of a patient with Crohn's disease. Deeper knowledge of all the biological and clinical features will allow appropriate and specific treatment of this tumor in the future.

KRAS and BRAF Mutations in Stage II/III Colon Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

KRAS and BRAF mutations are well-established predictive and prognostic factors in metastatic colorectal cancer, however their impact in the adjuvant setting has not yet been established.

METHODS

We performed a meta-analysis of adjuvant phase III trials in patients with stage II and III colon cancer with available data on the impact of KRAS/BRAF mutations on both disease-free survival (DFS) and overall survival (OS). Trials were subgrouped based on whether adjustment for microsatellite instability (MSI) was performed and the subgroup effect was analyzed through a meta-regression. To increase the precision of the estimates, a joint DFS/OS (so-called 'multivariate') meta-analysis was performed. All statistical tests were 2-sided.

RESULTS

Nine trials were selected (QUASAR 2, PETACC-8, N0147, CALGB-89803, NSABP-C07, NSABP-C08, PETACC-3, QUASAR, MOSAIC) including a total of 10893 patients. In the primary meta-analysis, KRAS mutation was associated with poor DFS (pooled HR = 1.36, 95% CI = 1.15-1.61, P < .001) and OS (pooled HR = 1.27, 95% CI = 1.03-1.55, P = .03) and BRAF mutation was also associated with poor DFS (pooled HR = 1.33, 95% CI = 1.00-1.78, P = .05) and OS (pooled HR = 1.49, 95% CI = 1.31-1.70, P < .001). MSI adjustment enhanced the effect of the mutations on outcome in the MSI-adjusted subgroup for both the KRAS mutation (pooled HR for DFS = 1.43, 95% CI = 1.15-1.79, P = .001; and pooled HR for OS = 1.33, 95% CI = 1.03-1.71, P = .03) and the BRAF mutation (pooled HR for DFS = 1.59, 95% CI = 1.22-2.07, P = .001; and pooled HR for OS = 1.67, 95% CI = 1.37-2.04, P < .001). The interaction between BRAF and MSI adjustment was statistically significant for DFS (P interaction = 0.02). This interaction was even more pronounced in the DFS/OS multivariate meta-analysis.

CONCLUSIONS

Both KRAS and BRAF mutations were statistically significantly associated with both DFS and OS, with the mutation effect being enhanced by MSI adjustment. Effective adjuvant treatment for microsatellite stable BRAF or KRAS-mutated colon cancer represents an unmet clinical need and exploring the use of recently available BRAF and KRAS inhibitors in this setting would be highly desirable.

Precision oncology in metastatic colorectal cancer - from biology to medicine

Remarkable progress has been made in the development of biomarker-driven targeted therapies for patients with multiple cancer types, including melanoma, breast and lung tumours, although precision oncology for patients with colorectal cancer (CRC) continues to lag behind. Nonetheless, the availability of patient-derived CRC models coupled with in vitro and in vivo pharmacological and functional analyses over the past decade has finally led to advances in the field. Gene-specific alterations are not the only determinants that can successfully direct the use of targeted therapy. Indeed, successful inhibition of BRAF or KRAS in metastatic CRCs driven by activating mutations in these genes requires combinations of drugs that inhibit the mutant protein while at the same time restraining adaptive resistance via CRC-specific EGFR-mediated feedback loops. The emerging paradigm is, therefore, that the intrinsic biology of CRC cells must be considered alongside the molecular profiles of individual tumours in order to successfully personalize treatment. In this Review, we outline how preclinical studies based on patient-derived models have informed the design of practice-changing clinical trials. The integration of these experiences into a common framework will reshape the future design of biology-informed clinical trials in this field.

Effect of sidedness on survival among patients with early-stage colon cancer: a SEER-based propensity score matching analysis

BACKGROUND

Most previous studies compared survival between left-sided and right-sided colon cancer without adjustment for clinicopathological parameters. We investigated the effect of sidedness on survival among patients with early-stage colon cancer, using a propensity score matching method.

METHODS

The 18 registry custom data within the SEER database were used to identify patients who were diagnosed with colon cancer between 2010 and 2014. A propensity score matching analysis was performed using the nearest neighbor method. Survival was estimated using the Kaplan-Meier method. A Cox proportional hazards model was applied to determine the prognostic factors.

RESULTS

In the unmatched cohort, 25,094 (35.72%) patients were diagnosed with left-sided colon cancer and 45,156 (64.28%) with right-sided colon cancer. After propensity score matching, each cohort included 5118 patients, and the clinicopathological characteristics were well balanced. In the unmatched cohort, left-sided colon cancer had superior all-cause (χ²=315, P<0.01) and cancer-specific (χ²=43, P<0.01) survival than right-sided tumors. However, in the matched cohort, no difference was observed for all-cause (χ²=0.7, P=0.4) and cancer-specific (χ²=0, P=0.96) survival between left and right colon cancer. The Cox model did not indicate sidedness as a prognostic factor. In the subgroup analysis, stage II right-sided colon cancer had a better survival outcome, while stage III left-sided tumors had a better survival outcome.

CONCLUSIONS

After adjusting for clinicopathological characteristics in this study, sidedness showed no impact on survival in early-stage colon cancer. However, sidedness was associated with prognostic differences in stages II and III early-stage colon cancer.

Molecular profiling of the colon cancer in South-Eastern Romania: Results from the MERCUR study

ABSTRACT

Colorectal cancer is a heterogeneous disease with multiple epigenetic alterations and different molecular features. The molecular classification is based on 2 major distinct pathways: microsatellite stable pathway and the microsatellite instability pathway. Molecular profiling of colorectal cancer provides important information regarding treatment and prognosis. Aim of the study was to assess the frequency of microsatellite instability in colon cancer and the clinicopathological characteristics of the tumors with high level of microsatellite instability (MSI-H) in our region. The secondary outcome was to assess the frequency of v-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations in colon cancer.The study included 129 patients with colon cancer fit for surgery. Demographic data, clinical and pathological data, immunohistochemistry staining pattern (4 mismatch repair proteins were investigated), and BRAF gene mutations were assessed. According to microsatellite instability status by polymerase chain reaction, patients were divided into 3 groups: microsatellite stable (MSS) = 108 patients, high level of microsatellite instability (MSI-H) = 15 patients and low level of microsatellite instability (MSI-L) = 6 patients. Different clinicopathological comparisons between MSS and MSI-H patients, and between MSS and MSI-L patients were performed.Microsatellite instability was found in 16.3% patients: 11.6% had MSI-H and 4.7% had MSI-L. Significantly more patients in the MSI-H group than in the MSS group were female (P = .01) and had a family history of colon cancer (P < .001). MSI-H and MSI-L groups were associated with the ascending colon location of the tumors, were mostly type G3, T2, and stage I whereas MSS tumors were mostly G2, pT3, and stage III. Overall, BRAF mutations were identified in 18/129 patients (13.9%). BRAF mutant tumors were predominantly associated with MSI-H and MSI-L tumors. Immunohistochemistry had a sensitivity of 76% and a specificity of 89% in detecting MSI tumors and an accuracy of 87.6%.The frequency of microsatellite instability in our study was 16.3%. MSI-H is a distinct molecular phenotype of colon cancer with particular features: female gender, family history of colorectal cancer, a predilection for the ascending colon, poorly differentiated, predominantly T2, and stage I. The frequency of BRAF mutations was 13.9% and mutations were more often present in the MSI tumors.

BRAF: A Two-Faced Janus

Gain-of-function of V-Raf Murine Sarcoma Viral Oncogene Homolog B (BRAF) is one of the most frequent oncogenic mutations in numerous cancers, including thyroid papillary carcinoma, melanoma, colon, and lung carcinomas, and to a lesser extent, ovarian and glioblastoma multiforme. This mutation aberrantly activates the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway, thereby eliciting metastatic processes. The relevance of BRAF mutations stems from its prognostic value and, equally important, from its relevant therapeutic utility as an actionable target for personalized treatment. Here, we discuss the double facets of BRAF. In particular, we argue the need to implement diagnostic molecular algorithms that are able to detect this biomarker in order to streamline and refine diagnostic and therapeutic decisions.

The Role of BRAF in Metastatic Colorectal Carcinoma-Past, Present, and Future

With a global incidence of 1.8 million cases, colorectal cancer represents one of the most common cancers worldwide. Despite impressive improvements in treatment efficacy through cytotoxic and biological agents, the cancer-related death burden of metastatic colorectal cancer (mCRC) is still high. mCRC is not a genetically homogenous disease and various mutations influence disease development. Up to 12% of mCRC patients harbor mutations of the signal transduction molecule BRAF, the most prominent being BRAFV600E. In mCRC, BRAFV600E mutation is a well-known negative prognostic factor, and is associated with a dismal prognosis. The currently approved treatments for BRAF-mutated mCRC patients are of little impact, and there is no treatment option superior to others. However, the gradual molecular understanding over the last decades of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway, resulted in the development of new therapeutic strategies targeting the involved molecules. Recently published and ongoing studies administering a combination of different inhibitors (e.g., BRAF, MEK, and EGFR) showed promising results and represent the new standard of care. In this review, we present, both, the molecular and clinical aspects of BRAF-mutated mCRC patients, and provide an update on the current and future treatment approaches that might direct the therapy of mCRC in a new era.

BRAF Mutation in Colorectal Cancers: From Prognostic Marker to Targetable Mutation

Simple Summary

Colorectal cancer with a mutation in an oncogene BRAF has paid much attention, as it comprises a population with dismal prognosis since two decades ago. A series of research since then has successfully changed this malignancy to be treatable with specific treatment. Here we thoroughly overviewed the basic, translational and clinical studies on colorectal cancer with BRAF mutation from a physician’s viewpoint. Accumulating lines of evidence suggest that intervention of the trunk cellular growth signal transduction pathway, namely EGFR-RAS-RAF-MEK-ERK pathway, is a clue to controlling this disease. However, it is not so straightforward. Recent studies unveil the diverse and plastic nature of this signal transduction pathway. We will introduce our endeavor to conquer this condition, based on newly arriving datasets, and discuss how we could open the door to future development of CRC treatment.

Abstract

The Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is detected in 8–12% of metastatic colorectal cancers (mCRCs) and is strongly correlated with poor prognosis. The recent success of the BEACON CRC study and the development of targeted therapy have led to the determination of BRAF-mutated mCRCs as an independent category. For nearly two decades, a growing body of evidence has established the significance of the BRAF mutation in the development of CRC. Herein, we overview both basic and clinical data relevant to BRAF-mutated CRC, mainly focusing on the development of treatment strategies. This review is organized into eight sections, including clinicopathological features, molecular features, prognosis, the predictive value of anti-epidermal growth factor receptor (EGFR) therapy, resistant mechanisms for BRAF-targeting treatment, the heterogeneity of the BRAF mutation, future perspectives, and conclusions. A characterization of the canonical mitogen-activated protein kinase (MAPK) pathway is essential for controlling this malignancy, and the optimal combination of multiple interventions for treatments remains a point of debate.

Precision medicine for adjuvant chemotherapy of resected colorectal cancer

Colorectal cancer (CRC) is the most common cancer and the second leading cause of cancer death in Japan. Surgical resection is the only curative option for localized disease. However, undetectable micrometastases remaining after curative surgery may cause disease recurrence. Adjuvant chemotherapy aims to eradicate these micrometastases to improve the cure rate. Unfortunately, few reliable prognostic and predictive markers are available that identify patients at high risk for CRC during early-stage disease. However, promising biomarkers may become available in the near future. Such biomarkers provide information for stratifying a patient's risk and for selecting the optimal treatment. Here, we provide an overview of current relevant prognostic and predictive biomarkers applicable to adjuvant treatment of early-stage CRC and focus on the future of this field.

Mast Cells, microRNAs and Others: The Role of Translational Research on Colorectal Cancer in the Forthcoming Era of Precision Medicine

Colorectal cancer (CRC) is a heterogeneous disease, molecularly and anatomically, that develops in a multi-step process requiring the accumulation of several genetic or epigenetic mutations that lead to the gradual transformation of normal mucosa into cancer. In fact, tumorigenesis is extremely complex, with many immunologic and non-immunologic factors present in the tumor microenvironment that can influence tumorigenesis. In the last few years, a role for mast cells (MCs), microRNAs (miRNAs), Kirsten rat sarcoma (KRAS) and v-raf murine sarcoma viral oncogene homologue B (BRAF) in cancer development and progression has been suggested, and numerous efforts have been made to thoroughly assess their correlation with CRC to improve patient survival and quality of life. The identification of easily measurable, non-invasive and cost-effective biomarkers, the so-called "ideal biomarkers", for CRC screening and treatment remains a high priority. The aim of this review is to discuss the emerging role of mast cells (MCs), microRNAs (miRNAs), KRAS and BRAF as diagnostic and prognostic biomarkers for CRC, evaluating their influence as potential therapy targets in the forthcoming era of precision medicine.

Lysine-specific histone demethylase 1B (LSD2/KDM1B) represses p53 expression to promote proliferation and inhibit apoptosis in colorectal cancer through LSD2-mediated H3K4me2 demethylation

Epigenetic alterations have been reported to play critical roles in the development of colorectal cancer (CRC). However, the biological function of the lysine-specific histone demethylase 1B (LSD2/KDM1B) in CRC is not well understood. Therefore, we investigated the characteristics of LSD2 in CRC. We observed significant upregulation of LSD2 in CRC tissue compared to that in normal colorectal tissue. LSD2 promotes CRC cell proliferation and inhibits cell apoptosis through cell cycle regulation, promoting CRC progression both in vitro and in vivo. We found that LSD2 performs these functions by inhibiting the p53-p21-Rb pathway. Finally, we found that LSD2 directly binds to p53 and represses p53 expression via H3K4me2 demethylation at the p53 promoter. Our results revealed that LSD2 acts as an oncogene by binding and inhibiting p53 activity in CRC. Thus, LSD2 may be a new molecular target for CRC treatment.

Association Between Molecular Subtypes of Colorectal Tumors and Patient Survival, Based on Pooled Analysis of 7 International Studies

BACKGROUND AND AIMS

The heterogeneity among colorectal tumors is probably due to differences in developmental pathways and might associate with patient survival times. We studied the relationship among markers of different subtypes of colorectal tumors and patient survival.

METHODS

We pooled data from 7 observational studies, comprising 5010 patients with colorectal cancer. All the studies collected information on microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and mutations in KRAS and BRAF in tumors. Tumors with complete marker data were classified as type 1 (MSI-high, CIMP-positive, with pathogenic mutations in BRAF but not KRAS), type 2 (not MSI-high, CIMP-positive, with pathogenic mutations in BRAF but not KRAS), type 3 (not MSI-high or CIMP, with pathogenic mutations in KRAS but not BRAF), type 4 (not MSI-high or CIMP, no pathogenic mutations in BRAF or KRAS), or type 5 (MSI-high, no CIMP, no pathogenic mutations in BRAF or KRAS). We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for associations of these subtypes and tumor markers with disease-specific survival (DSS) and overall survival times, adjusting for age, sex, stage at diagnosis, and study population.

RESULTS

Patients with type 2 colorectal tumors had significantly shorter time of DSS than patients with type 4 tumors (HR_DSS 1.66; 95% CI 1.33-2.07), regardless of sex, age, or stage at diagnosis. Patients without MSI-high tumors had significantly shorter time of DSS compared with patients with MSI-high tumors (HR_DSS 0.42; 95% CI 0.27-0.64), regardless of other tumor markers or stage, or patient sex or age.

CONCLUSIONS

In a pooled analysis of data from 7 observational studies of patients with colorectal cancer, we found that tumor subtypes, defined by combinations of 4 common tumor markers, were associated with differences in survival time. Colorectal tumor subtypes might therefore be used in determining patients' prognoses.

Associations between molecular characteristics of colorectal serrated polyps and subsequent advanced colorectal neoplasia

PURPOSE

BRAF mutation and DNA hypermethylation have linked sessile serrated adenomas/polyps (SSA/Ps) to serrated colorectal cancer (CRC) in cross-sectional studies, but they have not been evaluated in a longitudinal study. We aimed to evaluate the associations between molecular markers of serrated polyps and subsequent advanced colorectal neoplasia.

METHODS

Study subjects included Kaiser Permanente Washington members aged 20-75 years who received an index colonoscopy between 1/1/1998 and 12/31/2007 and had hyperplastic polyps (HPs) or SSA/Ps according to study pathology review. Polyps from index colonoscopies were removed and assayed for BRAF mutation, CpG island methylator phenotype (CIMP), and MLH1 methylation. Pathology reports and biopsies from the subsequent lower gastrointestinal endoscopy through 1/1/2013 were reviewed for advanced colorectal neoplasia. We identified additional incident CRC cases through linkage to the Seattle-Puget Sound Surveillance Epidemiology and End Results registry. We used generalized estimating equations to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) for subsequent advanced colorectal neoplasia, comparing index serrated polyps with different molecular markers.

RESULTS

We included 553 individuals with index serrated polyps (420 HPs and 133 SSA/Ps) and 795 subsequent endoscopies. The prevalence of BRAF-mutant, CIMP-high, and MLH1-methylated serrated polyps were 51%, 4%, and 2%, respectively. BRAF and CIMP were not associated with subsequent advanced colorectal neoplasia. MLH1-methylated SSP/As were significantly more likely to have subsequent advanced neoplasia (OR = 4.66, 95% CI 1.06-20.51).

CONCLUSION

Our results suggest that BRAF-mutant and CIMP-high serrated polyps are not associated with subsequent advanced colorectal neoplasia. Among SSA/Ps, MLH1 methylation may be an important marker to identify high-risk CRC precursors.

The Role of Anti-Angiogenics in Pre-Treated Metastatic BRAF-Mutant Colorectal Cancer: A Pooled Analysis

Background. FOLFOXIRI plus Bevacizumab is one of the most frequently used first-line treatments for patients with BRAF-mutant colorectal cancer (CRC), while second-line treatment requires extensive further research. In this pooled analysis, we evaluate the impact of anti-angiogenics in patients with pre-treated BRAF-mutant CRC. Methods. We monitored patients in randomized, controlled studies who had advanced CRC and were undergoing second-line chemotherapy in addition to utilizing Bevacizumab, Ramucirumab or Aflibercept treatments. These data were pooled together with the data and results of BRAF-mutant patients enrolled in two phase III trials (TRIBE and TRIBE-2 study), who had been treated with second-line treatment both with or without Bevacizumab. Overall survival (OS), in relation to BRAF mutational status, was the primary focus. Results. Pooled analysis included 129 patients. Anti-angiogenics were found to have a significant advantage over the placebo in terms of OS (HR 0.50, 95%CI 0.29-0.85) (p = 0.01). Conclusions. Our pooled analysis confirms the efficacy of anti-angiogenics in pre-treated BRAF-mutant CRC, establishing the combination of chemotherapy plus Bevacizumab or Ramucirumab or Aflibercept as a valid treatment option.

BRAF-V600E and microsatellite instability prediction through CA-19-9/CEA ratio in patients with colorectal cancer

BACKGROUND

Early identification of colorectal cancer (CRC) patients that are BRAF-V600E mutant and/or microsatellite instability-high (MSI-High), has both prognostic and predictive value. We wanted to highlight an observation of utilizing 2 simple, rapid and universally available lab tests, i.e., carbohydrate cancer antigen 19-9 (CA 19-9) and carcinoembryonic antigen (CEA) tumor markers, the ratio (CA-19-9/CEA) of which can distinctly identify these patients from other molecular subsets of CRC.

METHODS

All patients with metastatic CRC from December 2016 to February 2019 were identified, and included in the study if they had both CA19-9 and CEA tests available. Circulating tumor DNA (ctDNA) testing and tissue genetic testing results were used to categorize patients into BRAF V600E microsatellite stable (MSS), MSI-High, RAS mutant MSS and RAS/RAF wild type CRCs. Kruskal-Wallis test was used to compare the CA19-9/CEA ratio between mutation types and the pairwise p values were adjusted for multiple comparisons with Holm method. For sensitivity analysis, the same analysis was repeated for the mean and median ratio of each patient. All tests were two-sided with alpha level set at 0.05 for statistical significance.

RESULTS

BRAF-V600E MSS CRC patients had a discordantly profound elevation in CA-19-9 levels as opposed to the CEA levels. Patients in the BRAF V600E MSS subset had the highest median CA19-9/CEA ratio versus the least median ratio in MSI-High patients. The median of maximum CA-19-9/CEA ratio was 28.92 (range, 2.76-707.27) in BRAF-V600E MSS patients and 4.06 (range, 0.46-166.74) in MSI-High subset of patients.

CONCLUSIONS

To date, this is the first report utilizing the ratio of tumor markers CA19-9/CEA as a predictive rather than just prognostic tool to identify BRAF-V600E MSS and MSI-High CRC patients.

Dietary Insulin Load and Cancer Recurrence and Survival in Patients With Stage III Colon Cancer: Findings From CALGB 89803 (Alliance)

BACKGROUND

Evidence suggests that diets inducing postprandial hyperinsulinemia may be associated with increased cancer-related mortality. The goal of this study was to assess the influence of postdiagnosis dietary insulin load and dietary insulin index on outcomes of stage III colon cancer patients.

METHODS

We conducted a prospective observational study of 1023 patients with resected stage III colon cancer enrolled in an adjuvant chemotherapy trial who reported dietary intake halfway through and six months after chemotherapy. We evaluated the association of dietary insulin load and dietary insulin index with cancer recurrence and survival using Cox proportional hazards regression adjusted for potential confounders; statistical tests were two-sided.

RESULTS

High dietary insulin load had a statistically significant association with worse disease-free survival (DFS), comparing the highest vs lowest quintile (adjusted hazard ratio [HR] = 2.77, 95% confidence interval [CI] = 1.90 to 4.02, Ptrend < .001). High dietary insulin index was also associated with worse DFS (highest vs lowest quintile, HR = 1.75, 95% CI = 1.22 to 2.51, Ptrend= .01). The association between higher dietary insulin load and worse DFS differed by body mass index and was strongest among patients with obesity (HR = 3.66, 95% CI = 1.88 to 7.12, Pinteraction = .04). The influence of dietary insulin load on cancer outcomes did not differ by mutation status of KRAS, BRAF, PIK3CA, TP53, or microsatellite instability.

CONCLUSIONS

Patients with resected stage III colon cancer who consumed a high-insulinogenic diet were at increased risk of recurrence and mortality. These findings support the importance of dietary management following resection of colon cancer, and future research into underlying mechanisms of action is warranted.

Unique characteristics of CpG island methylator phenotype (CIMP) in a Chinese population with colorectal cancer

Background

Molecular characteristics of CpG island methylator phenotype (CIMP) in colorectal cancer (CRC) have been well documented in Western, but not in Chinese, populations.

Methods

We investigated the incidence of CIMP, BRAF/KRAS mutation, and microsatellite instability (MSI) in a Chinese population with CRC (n = 401) and analysed associations between CIMP status and clinicopathological and molecular features.

Results

A total of 41 cases, 310 cases, and 40 cases were classified as CIMP-high, CIMP-low, and CIMP-negative, respectively. We detected a significantly low incidence of BRAF mutation in adenomas (2%) and CRC (0.7%), and a relatively low incidence of KRAS mutation (24.9%) compared with that in other populations. We also detected a relatively low incidence of CIMP-high (10.2%), which was significantly associated with younger age (≤49 years of age), female sex, and proximal tumour location.

Conclusions

This study revealed unique characteristics of CIMP in a Chinese population with colorectal cancer. Developing specific CIMP markers based on unique populations or ethnic groups will further help to fully elucidate CIMP pathogenesis.

BRAF-Mutated Colorectal Cancer: Clinical and Molecular Insights

Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity in the world. It is a heterogeneous disease, which can be classified into different subtypes, characterized by specific molecular and morphological alterations. In this context, BRAF mutations are found in about 10% of CRC patients and define a particular subtype, characterized by a dismal prognosis, with a median survival of less than 12 months. Chemotherapy plus bevacizumab is the current standard therapy in first-line treatment of BRAF-mutated metastatic CRC (mCRC), with triplet (FOLFOXIRI) plus bevacizumab as a valid option in patients with a good performance status. BRAF inhibitors are not so effective as compared to melanoma, because of various resistance mechanisms. However, the recently published results of the BEACON trial will establish a new standard of care in this setting. This review provides insights into the molecular underpinnings underlying the resistance to standard treatment of BRAF-mutated CRCs, with a focus on their molecular heterogeneity and on the research perspectives both from a translational and a clinical point of view.

Genomic Profiling of Blood-Derived Circulating Tumor DNA from Patients with Colorectal Cancer: Implications for Response and Resistance to Targeted Therapeutics

Molecular profiling of circulating tumor DNA (ctDNA) is a promising noninvasive tool. Here, next-generation sequencing (NGS) of blood-derived ctDNA was performed in patients with advanced colorectal cancer. We investigated ctDNA-derived genomic alterations, including potential actionability, concordance with tissue NGS, and serial dynamics in 78 patients with colorectal cancer using a clinical-grade NGS assay that detects single nucleotide variants (54-73 genes) and selected copy-number variants, fusions, and indels. Overall, 63 patients [80.8% (63/78)] harbored ctDNA alterations; 59 [75.6% (59/78)], ≥1 characterized alteration (variants of unknown significance excluded). All 59 patients had actionable alterations potentially targetable with FDA-approved drugs [on-label and/or off-label (N = 54) or with experimental drugs in clinical trials (additional five patients); University of California San Diego Molecular Tumor Board assessment]: 45, by OncoKB (http://oncokb.org/#/). The tissue and blood concordance rates for common specific alterations ranged from 62.3% to 86.9% (median = 5 months between tests). In serial samples from patients on anti-EGFR therapy, multiple emerging alterations in genes known to be involved in therapeutic resistance, including KRAS, NRAS, BRAF, EGFR, ERBB2, and MET were detected. In conclusion, over 80% of patients with stage IV colorectal cancer had detectable ctDNA, and the majority had potentially actionable alterations. Concordance between tissue and blood was between 62% and 87%, despite a median of 5 months between tests. Resistance alterations emerged on anti-EGFR therapy. Therefore, biopsy-free, noninvasive ctDNA analysis provides data relevant to the clinical setting. Importantly, sequential ctDNA analysis detects patterns of emerging resistance allowing for precision planning of future therapy.

TYMS/KRAS/BRAF molecular profiling predicts survival following adjuvant chemotherapy in colorectal cancer

BACKGROUND

Patients with stage II-III colorectal cancer (CRC) treated with adjuvant chemotherapy, gain a 25% survival benefit. In the context of personalized medicine, there is a need to identify patients with CRC who may benefit from adjuvant chemotherapy. Molecular profiling could guide treatment decisions in these patients. Thymidylate synthase (TYMS) gene polymorphisms, KRAS and BRAF could be included in the molecular profile under consideration.

AIM

To investigate the association of TYMS gene polymorphisms, KRAS and BRAF mutations with survival of CRC patients treated with chemotherapy.

METHODS

A retrospective study studied formalin-fixed paraffin-embedded tissues (FFPEs) of consecutive patients treated with adjuvant chemotherapy during January/2005-January/2007. FFPEs were analysed with PCR for the detection of TYMS polymorphisms, mutated KRAS (mKRAS) and BRAF (mBRAF). Patients were classified into three groups (high, medium and low risk) according to 5’UTR TYMS polymorphisms Similarly, based on 3’UTR polymorphism ins/loss of heterozygosity (LOH) patients were allocated into two groups (high and low risk of relapse, respectively). Cox regression models examined the associated 5-year survival outcomes.

RESULTS

One hundred and thirty patients with early stage CRC (stage I-II: 55 patients; stage III 75 patients; colon: 70 patients; rectal: 60 patients) were treated with surgery and chemotherapy. The 5-year disease free survival and overall survival rate was 61.6% and 73.9% respectively. 5’UTR polymorphisms of intermediate TYMS polymorphisms (2RG/3RG, 2RG/LOH, 3RC/LOH) were associated with lower risk for relapse [hazard ratio (HR) 0.320, P = 0.02 and HR 0.343, P = 0.013 respectively] and death (HR 0.368, P = 0.031 and HR 0.394, P = 0.029 respectively). The 3’UTR polymorphism ins/LOH was independently associated with increased risk for disease recurrence (P = 0.001) and death (P = 0.005). mBRAF (3.8% of patients) was associated with increased risk of death (HR 4.500, P = 0.022) whereas mKRAS (39% of patients) not.

CONCLUSION

Prospective validating studies are required to confirm whether 2RG/3RG, 2RG/LOH, 3RC/LOH, absence of ins/LOH and wild type BRAF may indicate patients at lower risk of relapse following adjuvant chemotherapy.

Influence of Molecular Status on Recurrence Site in Patients Treated for a Stage III Colon Cancer: a Post Hoc Analysis of the PETACC-8 Trial

BACKGROUND

Recurrence patterns in stage III colon cancer (CC) patients according to molecular markers remain unclear. The objective of the study was to assess recurrence patterns according to microsatellite instability (MSI), RAS and BRAF^V600E status in stage III CC patients.

METHODS

All stage III CC patients from the PETACC-8 randomized trial tested for MSI, RAS and BRAF^V600E status were included. The site and characteristics of recurrence were analyzed according to molecular status. Survival after recurrence (SAR) was analyzed.

RESULTS

A total of 1650 patients were included. Recurrence occurred in 434 patients (26.3%). Microsatellite stable (MSS) patients had a significantly higher recurrence rate (27.2% vs. 18.7%, P = 0.02) with a trend to more pulmonary recurrence (28.8% vs. 12.9%, P = 0.06) when compared to MSI patients. MSI patients experienced more regional lymph nodes compared to MSS (12.9% vs. 4%, P = 0.046). In the MSS population, the recurrence rate was significantly higher in RAS (32.2%) or BRAF (32.3%) patients when compared to double wild-type patients (19.9%) (p < 0.001); no preferential site of recurrence was observed according to RAS and BRAF^V600E mutations. Finally, decreased SAR was observed in the case of peritoneal recurrence or more than two recurrence sites.

CONCLUSIONS

Microsatellite, RAS and BRAF^V600E status influences recurrence rates in stage III CC patients. However, only microsatellite status seems to be associated with specific recurrence patterns. More than two recurrence sites and recurrence in the peritoneum were associated with poorer SAR.

Prognostic impact of tumor location in colon cancer: the Monitoring of Cancer Incidence in Japan (MCIJ) project

BACKGROUND

Colorectal cancer (CRC) is globally one of the most common cancers. Although studies have found a significant prognostic impact of cancer location for right-sided colon cancers compared with those of the left-side, evidence is lacking in a Japanese population. Therefore, we investigated 5-year net survival in colon cancer by tumor site in a Japanese population.

METHODS

Diagnoses obtained between 2006 and 2008 in 21 population-based cancer registries from the Monitoring of Cancer Incidence in Japan (MCIJ) project were used. Colon cancer patients were categorized as having right-sided (C18.0-18.4) or left-sided colon cancer (C18.5-C18.7). We calculated the 5-year net survival for subjects diagnosed from 2006 until 2008 by anatomical subsite according to sex, age groups, tumor stage at diagnosis. We applied the excess mortality model to calculate excess hazard ratios (EHRs) and 95% confidential intervals (CIs) with and without adjustment for age, sex and cancer stages to evaluate the effect of location of colon cancer.

RESULTS

This study analyzed a total of 62,350 colon cancer subjects. Five-year net survivals for subjects with left- and right-sided colon cancer were 74.0% (95% CI, 73.4-74.7%) and 70.4% (95% CI, 69.7-71.0%), respectively. Compared with left-sided colon cancers, the EHR for right-sided colon cancers was 1.20 (95% CI, 1.16-1.25) after adjustment for age, sex and stage.

CONCLUSION

Our study found that the net survival for right-sided colon cancer was significantly lower than that for left-sided colon cancer. The anatomical site of cancer in the colon might be an important stratification factor in future studies of colon cancer.

Prognostic association of PTGS2 (COX-2) over-expression according to BRAF mutation status in colorectal cancer: Results from two prospective cohorts and CALGB 89803 (Alliance) trial

BACKGROUND

Prostaglandin-endoperoxide synthase 2 (PTGS2, cyclooxygenase-2, COX-2)-prostaglandin E2 (PGE2) pathway promotes tumour progression. Considering evidence suggesting increased PGE2 synthesis by BRAF mutation in tumour cells, we hypothesised that the association of tumour PTGS2 (COX-2) expression with colorectal cancer mortality might be stronger in BRAF-mutated tumours than in BRAF-wild-type tumours.

METHODS

Using 1708 patients, including 1200 stage I-IV colorectal carcinoma cases in the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS) and 508 stage III colon cancer cases in a National Cancer Institute-sponsored randomised controlled trial of adjuvant therapy (CALGB/Alliance 89803), we evaluated tumour PTGS2 (COX-2) expression status using immunohistochemistry. We examined the prognostic association of PTGS2 (COX-2) expression in strata of BRAF mutation status by multivariable Cox proportional hazards regression models to adjust for potential confounders, including disease stage, tumour differentiation, microsatellite instability status and KRAS and PIK3CA mutations.

RESULTS

In NHS and HPFS, the association of PTGS2 (COX-2) expression with colorectal cancer-specific survival differed by BRAF mutation status (Pinteraction = 0.0005); compared with PTGS2 (COX-2)-negative/low carcinomas, the multivariable-adjusted hazard ratios for PTGS2 (COX-2)-high carcinomas were 2.44 (95% confidence interval, 1.39-4.28) in BRAF-mutated cases and 0.82 (95% confidence interval, 0.65-1.04) in BRAF-wild-type cases. Differential prognostic associations of PTGS2 (COX-2) expression in strata of BRAF mutation status were similarly observed in CALGB/Alliance 89803 trial (Pinteraction = 0.03).

CONCLUSIONS

The association of tumour PTGS2 (COX-2) expression with colorectal cancer mortality is stronger in BRAF-mutated tumours than in BRAF-wild-type tumours, supporting interactive roles of PTGS2 (COX-2) expression and BRAF mutation statuses in prognostication of patients with colorectal cancer; ClinicalTrials.gov Identifier, NCT00003835.

Prognostic implications of mismatch repair deficiency in patients with nonmetastatic colorectal and endometrial cancer

Background

The clinical relevance of mismatch repair (MMR) status in patients with nonmetastatic cancer across tumour types remains unclear. Our goal was to investigate the prognostic role of MMR deficiency in patients with stage I-III colorectal and endometrial cancer.

Methods

Patients with nonmetastatic colorectal and endometrial cancer with tumour tissue available for analysis were identified through the Hellenic Cooperative Oncology Group (HeCOG)'s tumour repository. Patients had been referred to Departments of Medical Oncology affiliated with HeCOG. MMR protein expression was evaluated by immunohistochemistry. The primary outcome measure was overall survival (OS).

Results

From May 1990 to September 2012, 1158 patients with nonmetastatic colorectal (N = 991) and endometrial cancer (N = 167) were identified (median age: 64 years, men: 544). All patients with colorectal and 109 (65%) with endometrial cancer had received adjuvant treatment. MMR deficiency was observed in 114 (11.5%) of colorectal and 80 (47.9%) of endometrial tumours. More commonly deficient proteins were PMS2 (69 patients, 7%) and MLH1 (63 patients, 6.5%) in colorectal cancer and MSH2 (58 patients, 34.7%) in endometrial cancer. Colorectal MMR-deficient (dMMR) tumours were more likely to be right sided (65 % dMMR vs 27 % proficient MMR, pMMR; p < 0.001), high grade (31% vs 15%, χ², p < 0.001) and with a mucinous component (64% vs 42%, p < 0.001). Endometrial dMMR tumours were more often of endometrioid histology (51.4 % endometrioid vs 20 % serous/clear cell, p = 0.020). Compared with MMR proficiency, MMR deficiency was associated with improved OS in patients with endometrial cancer (HR = 0.38, 95% CI 0.20 to 0.76, p = 0.006), but not in patients with colorectal cancer (HR = 0.73, 95% CI 0.49 to 1.09, p = 0.130). After adjusting for age, stage and grade, MMR deficiency maintained its favourable prognostic significance in patients with endometrial cancer (HR = 0.42, 95% CI 0.20 to 0.88, p = 0.021).

Conclusions

DMMR was associated with improved outcomes in patients with nonmetastatic endometrial cancer, but not in patients with nonmetastatic colorectal cancer who received adjuvant chemotherapy.

Relationship between CpG island methylation phenotype, microsatellite instability phenotype and mutation of KRAS, NRAS, and BRAF genes in colorectal cancer

OBJECTIVE

CpG island methylation phenotype (CIMP) and microsatellite instability (MSI) are two different molecular mechanisms in colorectal cancer (CRC). Proto-oncogene KRAS, mutations in NRAS and BRAF play an important role in the formation of colorectal cancer. The correlation between the molecular typing of CIMP and MSI and the genes of KRAS, NRAS and BRAF was explored in this study.

METHODS

A total of 110 paraffin-embedded specimens of colorectal cancer were collected from the Chinese People's Liberation Army Rocket Army Special Medical Center during the period from May 2017 to September 2018. CIMP were detected by DNA methylation quantitative PCR (Methylight). Mutations in KRAS, NRAS, and BRAF genes were detected by realtime fluorescence quantitative PCR (qPCR); MSI typing was detected by sequencing.

RESULTS

Of the 110 colorectal cancer samples, 11 cases (10%) were CIMP-H, 92 cases (83.64%) were CIMP-L, and 7 cases (6.36%) were CIMP-0. 10 cases (9.09%) were MSI-H, and 100 cases (90.91%) were MSS and MSI-L. The mutation rates of KRAS, NRAS and BRAF genes were 50% (55 cases), 6.36% (7 cases) and 5.45% (6 cases), respectively. There was no significant correlation between CIMP group and MSI group (P > 0.05). Also, no significant differences were found in the mutations between the three subtypes of the CIMP group and the KRAS, NRAS genes (P > 0.05), while there was a statistically significant difference among the three subtypes of the BR and the BRAF gene mutations (P < 0.0001). There were no obvious differences between the three states of microsatellites and the mutations of KRAS and NRAS genes (P > 0.05), and the differences between them and BRAF gene mutations were statistically significant (P < 0.01).

CONCLUSIONS

The BRAF gene mutation is closely related to the two types of CIMP and MSI, which may be an important part of the above two molecular mechanisms, and provide a reference for the treatment of the patients with CIMP-H and MSI-H.