Clinical Significance and Prognostic Relevance of Microsatellite Instability in Sporadic Colorectal Cancer Patients

Is Risk-Stratifying Patients with Colorectal Cancer Using a Deep Learning-Based Prognostic Biomarker Cost-Effective?

OBJECTIVES

Accurate risk stratification of patients with stage II and III colorectal cancer (CRC) prior to treatment selection enables limited health resources to be efficiently allocated to patients who are likely to benefit from adjuvant chemotherapy. We aimed to investigate the cost-effectiveness of a recently developed deep learning-based prognostic method, Histotyping, from the perspective of the Norwegian healthcare system.

METHODS

Two partitioned survival models were developed to assess the cost-effectiveness of Histotyping for two treatment cohorts: patients with CRC stage II and III. For each of the two cohorts, Histotyping was used for risk stratification to assign adjuvant chemotherapy and was compared with the standard of care (SOC) (adjuvant chemotherapy to all patients). Health outcomes measured in the model were quality-adjusted life years (QALYs) and life years (LYs) gained. Deterministic and probabilistic sensitivity analyses were performed to determine the impact of uncertainty. Scenario analyses were performed to assess the impact of the parameters with the greatest uncertainty.

RESULTS

Risk-stratifying patients with CRC stage II and III using Histotyping was dominant (less costly and more effective) compared to SOC. In patients with CRC stage II, the net monetary benefit of Histotyping was 270,934 Norwegian kroners (NOK) (year of valuation is 2021), and the net health benefit of Histotyping was 0.99. In stage III, the net monetary benefit of Histotyping was 195,419 NOK, and the net health benefit of Histotyping was 0.71.

CONCLUSIONS

 Risk-stratifying patients with CRC using Histotyping prior to the administration of adjuvant chemotherapy is likely to be a cost-effective strategy in Norway.

A cloud-based precision oncology framework for whole genome sequence analysis

Cancer is one of the wide-ranging diseases which have a high mortality rate impacting globally. This scenario can be switched by early detection and correct precision treatment, a major concern for cancer patients. Clinicians can figure out the best-suited treatments for cancer patients by analyzing the patient's genome, which will treat the patient well and minimize the chances of side effects as well. Therefore, we have developed a fast, robust, and efficient solution as our precision oncology framework based on the whole genome sequencing of the individual's DNA. This platform can perform the entire genomic analysis, starting from the quality assessment of the input file to the variant annotation and functional prediction, followed by a certain level of interpretation. This analysis helps in the molecular profiling of the tumors for the identification of the targetable alterations. It takes in FASTQ or BAM file as an input and provides us with two output reports: a primary report, which consists of the patients' details, a summary of the analysis, and a secondary report, which is an elaborated report comprised of numerous results obtained from the analysis such as base changes, codon changes, amino acid changes, TMB analysis, MSI analysis, the variant frequency with its effects and impacts, affected biomarkers, etc. This framework can be effectively utilized for cancer treatment guidance, identification and validation of novel biomarkers, oncology research & development, genomic analysis, and gene manipulation.

Construction and validation of "WCH-nomogram" for predicting the prognosis after resection of colorectal liver metastases

BACKGROUND

The prognostic predictive tool for patients with colorectal liver metastasis (CRLM) is limited and the criteria for administering preoperative neoadjuvant chemotherapy in CRLM patients remain controversial.

METHODS

This study enrolled 532 CRLM patients at West China Hospital (WCH) from January 2009 to December 2019. Prognostic factors were identified from the training cohort to construct a WCH-nomogram and evaluating accuracy in the validation cohort. Receiver operating characteristic (ROC) curve analysis was used to compare the prediction accuracy with other existing prediction tools.

RESULTS

From the analysis of the training cohort, four independent prognostic risk factors, namely tumor marker score, KRAS mutation, primary lymph node metastasis, and tumor burden score were identified on which a WCH-nomogram was constructed. The C-index of the two cohorts were 0.674 (95% CI: 0.634-0.713) and 0.655 (95% CI: 0.586-0.723), respectively, which was better than the previously reported predication scores (CRS, m-CS and GAME score). ROC curves showed AUCs for predicting 1-, 3-, and 5-year overall survival (OS) of 0.758, 0.709, and 0.717 in the training cohort, and 0.860, 0.669, and 0.692 in the validation cohort, respectively. A cutoff value of 114.5 points was obtained for the WCH-nomogram total score based on the maximum Youden index of the ROC curve of 5-year OS. Risk stratification showed significantly better prognosis in the low-risk group, however, the high-risk group was more likely to benefit from neoadjuvant chemotherapy.

CONCLUSIONS

The WCH-nomogram demonstrates superior prognostic stratification compared to prior scoring systems, effectively identifying CRLM patients who may benefit the most from neoadjuvant chemotherapy.

DNA mismatch repair system regulates the expression of PD-L1 through DNMTs in cervical cancer

BACKGROUND

Cervical cancer (CC) is a potential clinical application of PD-1/PD-L1 inhibitor. We aimed to study the mechanism of DNA mismatch repair (MMR) system regulating the expression of PD-L1 in CC through DNA methyltransferase (DNMTs).

METHODS

We collected pathological specimens from 118 cases of CC to analyze the relationship between PD-L1 expression and DNMTs in different MMR states. RNA interference (RNAi) technique was used to simulate the formation of CC cell line with MMR deficiency (dMMR) state, and subcutaneous tumor formation experiment was carried out in nude mice to verify the relationship between PD-L1 expression and DNMTs in MMR state.

RESULTS

The PD-L1 positive rate in 118 cases of CC was 58.47%, while the microsatellite instability (MSI) status accounted for 5.93%. There was a significant difference in the expression of PD-L1 between patients within the dMMR and MMR proficient (pMMR) groups (χ2 = 21.405, P < 0.001). Subcutaneous inoculation after infection of Siha cells led to successful tumorigenesis in nude mice, accompanied by a significant increase in the level of PD-L1 expression in the mouse tumors, while the expression level of MLH1 and MSH2 protein decreased significantly. We also found that PD-L1 expression was closely related to the expression of DNMTs.

CONCLUSION

PD-L1 is universal expressed on the surface of CC cells, dMMR status enhances the expression of PD-L1 on the surface of CC cells, dMMR states of CC are related to the demethylation status of the PD-L1 gene promoter region.

Management of Colorectal Cancer Using Nanocarriers-based Drug Delivery for Herbal Bioactives: Current and Emerging Approaches

Colorectal cancer (CRC) is a complex and multifactorial disorder in middle-aged people. Several modern medicines are available for treating and preventing it. However, their therapeutic uses are limited due to drawbacks, such as gastric perforation, diarrhea, intestinal bleeding, abdominal cramps, hair loss, nausea, vomiting, weight loss, and adverse reactions. Hence, there is a continuous quest for safe and effective medicines to manage human health problems, like CRC. In this context, herbal medicines are considered an alternative disease control system. It has become popular in countries, like American, European, and Asian, due to its safety and effectiveness, which has been practiced for 1000 years. During the last few decades, herbal medicines have been widely explored through multidisciplinary fields for getting active compounds against human diseases. Several herbal bioactives, like curcumin, glycyrrhizin, paclitaxel, chlorogenic acid, gallic acid, catechin, berberine, ursolic acid, betulinic acid, chrysin, resveratrol, quercetin, etc., have been found to be effective against CRC. However, their pharmacological applications are limited due to low bioavailability and therapeutic efficacy apart from their several health benefits. An effective delivery system is required to increase their bioavailability and efficacy. Therefore, targeted novel drug delivery approaches are promising for improving these substances' solubility, bioavailability, and therapeutic effects. Novel carrier systems, such as liposomes, nanoparticles, micelles, microspheres, dendrimers, microbeads, and hydrogels, are promising for delivering poorly soluble drugs to the target site, i.e., the colon. Thus, the present review is focused on the pathophysiology, molecular pathways, and diagnostic and treatment approaches for CRC. Moreover, an emphasis has been laid especially on herbal bioactive-based novel delivery systems and their clinical updates.

Pathological features associated with metastasis in patients with early invasive (pT1) colorectal carcinoma in colorectal polyps

AIMS

Colorectal carcinoma (CRC) arising in a colorectal polyp with invasion limited to the submucosa is sufficiently treated by complete endoscopic resection alone in many cases. Histological features of the carcinoma including tumour size, vascular invasion and poor tumour differentiation or evidence of de-differentiation, such as tumour budding, are associated with a higher risk for metastasis such that oncological resection is recommended. However, most malignant polyps with these features do not have lymph node metastases at the time of resection, so there is a need for better refinement of the histological risk features.

METHODS AND RESULTS

A total of 437 consecutive colorectal polyps with submucosal invasive carcinoma from a single centre, 57 of which had metastatic disease, were supplemented by 30 cases with known metastatic disease from two additional centres. Clinical and histological features of the polyp cancers were reviewed looking for differences between the 87 cancers with metastatic disease and the remaining cases without metastasis. A subgroup of 204 polyps removed intact was also analysed to ensure maximum histological accuracy.

CONCLUSIONS

This study confirmed larger invasive tumour size, vascular invasion and poor tumour differentiation as adverse predictive features. Prominent peritumoral desmoplasia and high cytological grade were additional adverse features. A predictive logistic regression model comprised of (i) presence of any form of vascular invasion; (ii) presence of high tumour budding (BD3); (iii) width of invasive tumour component > 8 mm; (iv) depth of invasive tumour > 1.5 mm; and (v) the finding of prominent expansile desmoplasia located within and beyond the deep invasive edge of the carcinoma, showed excellent performance in predicting metastatic disease.

A radiomics model fusing clinical features to predict microsatellite status preoperatively in colorectal cancer liver metastasis

PURPOSE

To study the combined model of radiomic features and clinical features based on enhanced CT images for noninvasive evaluation of microsatellite instability (MSI) status in colorectal liver metastasis (CRLM) before surgery.

METHODS

The study included 104 patients retrospectively and collected CT images of patients. We adjusted the region of interest to increase the number of MSI-H images. Radiomic features were extracted from these CT images. The logistic models of simple clinical features, simple radiomic features, and radiomic features with clinical features were constructed from the original image data and the expanded data, respectively. The six models were evaluated in the validation set. A nomogram was made to conveniently show the probability of the patient having a high MSI (MSI-H).

RESULTS

The model including radiomic features and clinical features in the expanded data worked best in the validation group.

CONCLUSION

A logistic regression prediction model based on enhanced CT images combining clinical features and radiomic features after increasing the number of MSI-H images can effectively identify patients with CRLM with MSI-H and low-frequency microsatellite instability (MSI-L), and provide effective guidance for clinical immunotherapy of CRLM patients with unknown MSI status.

Stage III deficient mismatch repair colon patients get greater benefit from earlier starting oxaliplatin-based chemotherapy regimen

We evaluate the prognostic value of chemotherapy and other prognostic factors on overall survival among colon patients with deficient mismatch repair (dMMR), and determine the optimum time to start chemotherapy after surgery. Data of 306 colon cancer patients with dMMR who received radical surgery were collected from three Chinese centers between August 2012 and January 2018. Overall survival (OS) was assessed with the Kaplan-Meier method and log-rank. Cox regression analysis were used to assess influencing prognosis factors. The median follow-up time for all patients was 45.0 months (range, 1.0-100). There was a nonsignificant OS benefit from chemotherapy for patients with stage I and stage II disease, including high-risk stage II disease (log-rank p: 0.386, 0.779, 0.921), and a significant OS benefit for patients with stage III and stage IV disease for receiving post-operation chemotherapy (log-rank p = 0.002, 0.019). Stage III patients benefitted from chemotherapy regimens that contained oxaliplatin (log-rank p = 0.004), and Starting chemotherapy with oxaliplatin treatment earlier resulted in better outcomes (95% CI 0.013-0.857; p = 0.035). Chemotherapy regimens containing oxaliplatin can prolong the survival time of stage III and IV dMMR colon cancer patients. This beneficial manifestation was more pronounced after starting chemotherapy treatment early post operation. High risk stage II dMMR colon patients including T₄N₀M₀ cannot benefit from chemotherapy.

Identification of an m6A-related lncRNA prognostic signature in colorectal cancer

Data sets of colorectal cancer (CRC) were obtained from The Cancer Genome Atlas (TCGA), three N6-methyladenosine (m6A) subtypes were identified using 21 m6A-related long noncoding RNAs (lncRNAs) and differential m6A subtypes of different CRC tumors were determined in this study to evaluate the m6A expression and the prognosis of patients with CRC. Subsequently, eight key lncRNAs were identified based on co-expression with 21 m6A-related genes in CRC tumors using the single-factor Cox and least absolute shrinkage and selection operator. Finally, an m6A-related lncRNA risk score model of CRC tumor was established using multifactor Cox regression based on the eight important lncRNAs and found to have a better performance in evaluating the prognosis of patients in the TCGA-CRC data set. TCGA-CRC tumor samples were divided based on the risk scores: high and low. Then, the clinical characteristics, tumor mutation load, and tumor immune cell infiltration difference between the high- and low-risk-score groups were explored, and the predictive ability of the risk score was assessed for immunotherapeutic benefits. We found that the risk score model can determine the overall survival, be a relatively independent prognostic indicator, and better evaluate the immunotherapeutic benefits for patients with CRC. This study provides data support for accurate immunotherapy in CRC.

Systematic review of machine learning-based radiomics approach for predicting microsatellite instability status in colorectal cancer

This study aimed to systematically summarize the performance of the machine learning-based radiomics models in the prediction of microsatellite instability (MSI) in patients with colorectal cancer (CRC). It was conducted according to the preferred reporting items for a systematic review and meta-analysis of diagnostic test accuracy studies (PRISMA-DTA) guideline and was registered at the PROSPERO website with an identifier CRD42022295787. Systematic literature searching was conducted in databases of PubMed, Embase, Web of Science, and Cochrane Library up to November 10, 2022. Research which applied radiomics analysis on preoperative CT/MRI/PET-CT images for predicting the MSI status in CRC patients with no history of anti-tumor therapies was eligible. The radiomics quality score (RQS) and Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) were applied to evaluate the research quality (full score 100%). Twelve studies with 4,320 patients were included. All studies were retrospective, and only four had an external validation cohort. The median incidence of MSI was 19% (range 8-34%). The area under the receiver operator curve of the models ranged from 0.78 to 0.96 (median 0.83) in the external validation cohort. The median sensitivity was 0.76 (range 0.32-1.00), and the median specificity was 0.87 (range 0.69-1.00). The median RQS score was 38% (range 14-50%), and half of the studies showed high risk in patient selection as evaluated by QUADAS-2. In conclusion, while radiomics based on pretreatment imaging modalities had a high performance in the prediction of MSI status in CRC, so far it does not appear to be ready for clinical use due to insufficient methodological quality.

Identification of a Prognostic Colorectal Cancer Model Including LncRNA FOXP4-AS1 and LncRNA BBOX1-AS1 Based on Bioinformatics Analysis

Background: Knowledge about the prognostic role of long noncoding RNA (lncRNA) in colorectal cancer (CRC) is limited. Therefore, we constructed a lncRNA-related prognostic model based on data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). Materials and Methods: CRC transcriptome and clinical data were downloaded from the GSE20916 dataset and the TCGA database, respectively. R software was used for data processing and analysis. The differential lncRNA expression within the two datasets was first screened, and then intersections were measured. Cox regression and the Kaplan-Meier method were used to evaluate the effects of various factors on prognosis. The area under the curve (AUC) of the receiver operating characteristic curve and a nomogram based on multivariate Cox analysis were used to estimate the prognostic value of the lncRNA-related model. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were applied to elucidate the significantly involved biological functions and pathways. Results: A total of 11 lncRNAs were crossed. The univariate Cox analysis screened out two lncRNAs, which were analyzed in the multivariate Cox analysis. A nomogram based on the two lncRNAs and other clinicopathological risk factors was constructed. The AUC of the nomogram was 0.56 at 3 years and 0.71 at 5 years. The 3-year nomogram model was compared with the ideal model, which showed that some indices of the 3-year model were consistent with the ideal model, suggesting that our model was highly accurate. The GO and KEGG enrichment analyses showed that positive regulation of secretion by cells, positive regulation of secretion, positive regulation of exocytosis, endocytosis, and the calcium signaling pathway were differentially enriched in the two-lncRNA-associated phenotype. Conclusions: A two-lncRNA prognostic model of CRC was constructed by bioinformatics analysis. The model had moderate prediction accuracy. LncRNA BBOX1-AS1 and lncRNA FOXP4-AS1 were identified as prognostic biomarkers.

Effects of deficient mismatch repair on the prognosis of patients with stage II and stage III colon cancer during different postoperative periods

Background

We evaluated the prognostic role of deficient mismatch repair (dMMR) systems in stage II and stage III colon cancer patients during different postoperative periods. We also assessed whether patients aged ≥75 could benefit from chemotherapy.

Methods

This retrospective study was conducted across three medical centers in China. Kaplan–Meier survival methods and Cox proportional hazards models were used to evaluate the differences in overall survival (OS) and disease-free survival (DFS) rates. Propensity score matching was performed to reduce imbalances in the baseline characteristics of the patients. Landmark analysis was performed to evaluate the role of dMMR during different postoperative periods.

Results

The median follow-up time for all patients was 45.0 months (25–75 IQR: 38.0–82.5). There was no significant OS (p = 0.350) or DFS (p = 0.752) benefit associated with dMMR for stage II and III patients during the first postoperative year. However, significant OS (p < 0.001) and DFS (p < 0.001) benefits were observed from the second postoperative year until the end of follow-up. These differences remained after propensity score matching. Moreover, chemotherapy produced no OS (HR = 0.761, 95% CI: 0.43–1.34, p = 0.341) or DFS (HR = 0.98, 95% CI: 0.51–1.88, p = 0.961) benefit for patients aged ≥75 years.

Conclusion

The benefits of dMMR in stage III patients were observed from the second postoperative year until the end of follow-up. However, the prognosis of patients with dMMR is not different from that of patients with proficient mismatch repair (pMMR) during the first postoperative year. In addition, elderly patients aged ≥75 years obtained no significant survival benefits from postoperative chemotherapy.

Learn to Estimate Genetic Mutation and Microsatellite Instability with Histopathology H&E Slides in Colon Carcinoma

Colorectal cancer is one of the most common malignancies and the third leading cause of cancer-related mortality worldwide. Identifying KRAS, NRAS, and BRAF mutations and estimating MSI status is closely related to the individualized therapeutic judgment and oncologic prognosis of CRC patients. In this study, we introduce a cascaded network framework with an average voting ensemble strategy to sequentially identify the tumor regions and predict gene mutations & MSI status from whole-slide H&E images. Experiments on a colorectal cancer dataset indicate that the proposed method can achieve higher fidelity in both gene mutation prediction and MSI status estimation. In the testing set, our method achieves 0.792, 0.886, 0.897, and 0.764 AUCs for KRAS, NRAS, BRAF, and MSI, respectively. The results suggest that the deep convolutional networks have the potential to provide diagnostic insight and clinical guidance directly from pathological H&E slides.

The Potential Role of Genomic Signature in Stage II Relapsed Colorectal Cancer (CRC) Patients: A Mono-Institutional Study

Purpose

The absolute benefit of adjuvant chemotherapy in stage II CRC is only 3–4%. The identification of biomarkers through molecular profiling could identify patients who will more benefit from adjuvant chemotherapy.

Patients and Methods

This retrospective analysis examined tissue blocks from 17 patients affected by relapsed stage II CRC, whose comprehensive genomic profiling of tumors was conducted through next-generation sequencing (NGS) via Roche-FoundationOne^®.

Results

Mutations were found in APC (76.5%), TP53 (58.8%) and KRAS (52.9%). Only KRAS wild-type samples showed FBXW7. APC frameshift mutations and MLH1 splice variant were conversely significant correlated (7% v 93%, P = 0.014). The median number of gene mutations reported was 6 (range 2–14). The TP53 mutation was associated most frequently with lung metastasis (P = 0.07) and high tumor budding (P = 0.03). Despite no statistical significance, lung recurrence, LVI/Pni, MSI and more than 6 genetic mutations were correlated to worse DFS and OS. Patients carried co-mutations of TP53-FBXW7 reported the worse DFS (4 v 14 months) and OS (4 v 65 months) compared to the other patients.

Conclusion

According to the present analysis, the setting of relapsed CRC emerges as one of the fields of greatest utility for NGS, looking at personalized cancer care.

Update of gene expression/methylation and MiRNA profiling in colorectal cancer; application in diagnosis, prognosis, and targeted therapy

Background

Colorectal cancer is one of the most deadliest malignancies worldwide. Due to the dearth of appropriate biomarkers, the diagnosis of this mortal disease is usually deferred, in its turn, culminating in the failure of prevention. By the same token, proper biomarkers are at play in determining the quality of prognosis. In other words, the survival rate is contingent upon the regulation of such biomarkers.

Materials and methods

The information regarding expression (GSE41258, and GSE31905), methylation (GSE101764), and miRNA (dbDEMC) were downloaded. MEXPRESS and GEPIA confirmed the validated differentially expressed/methylated genes using TCGA data. Taking advantage of the correlation plots and receiver-operating-characteristic (ROC) curves, expression and methylation profiles were compared. The interactions between validated differentially expressed genes and differentially expressed miRNA were recognized and visualized by miRTarBase and Cytoscape, respectively. Then, the protein-protein interaction (PPI) network and hub genes were established via STRING and Cytohubba plugin. Utilizing R packages (DOSE, Enrichplot, and clusterProfiler) and DAVID database, the Functional Enrichment analysis and the detection of KEGG pathways were performed. Ultimately, in order to recognize the prognostic value of found biomarkers, they were evaluated through drawing survival plots for CRC patients.

Results

In this research, we found an expression profile (with 13 novel genes), a methylation profile (with two novel genes), and a miRNA profile with diagnostic value. Concerning diagnosis, the expression profile was evaluated more powerful in comparison with the methylation profile. Furthermore, a prognosis-related expression profile was detected.

Conclusion

In addition to diagnostic- and prognostic-applicability, the discerned profiles can assist in targeted therapy and current therapeutic strategies.

Mismatch repair protein deficiency assessed by immunohistochemistry in sporadic colorectal carcinoma

Context

Globally, colorectal carcinoma (CRC) ranks the third most commonly diagnosed malignant disease, one of the leading causes of cancer deaths.

Aims

To study the spectrum of clinicopathological characteristics of sporadic colorectal carcinoma and to assess mismatch repair gene deficiency by the expression pattern of the proteins assessed by immunohistochemistry.

Setting and Design

Observational study conducted in a tertiary care hospital in West Bengal.

Materials and Methods

Fifty-two surgically resected specimens of CRC received from January 2018 to May 2019 were studied for clinical, morphological, MSI status.

Statistical Analysis Used

IBM SPSS 23.

Results

A total of 50% of the cases belonged to younger and 50% to the older population, with male predominance being 53.8%. The most common histologic type was adenocarcinoma (88.5%). The majority was found to be well-differentiated carcinoma (50%). The majority cases were of the T3 stage accounting to 38.5%. A total of 24 out of 52 cases (46.15%) had an absent expression of at least one mismatch repair (MMR) protein. A significant correlation was found between the young age group and microsatellite instability (MSI) with a P value of 0.001. A significant association was found between MSI and tumor differentiation with P value of 0.018. A significant association was found between MSH6 and histological type with P value of 0.012. A significant association was found between MSI and tumor stage with P value of 0.032.

Conclusions

This study shows a significantly higher number of sporadic colon cancers involving the young age group, and younger cases showed significant association with MSI. This alarming trend needs validation by studies involving larger populations and can be helpful prognostically as well as in formulating chemotherapeutic regimens.

Exploring Serum NMR-Based Metabolomic Fingerprint of Colorectal Cancer Patients: Effects of Surgery and Possible Associations with Cancer Relapse

Background: Colorectal cancer (CRC) is the fourth most commonly diagnosed and third most deadly cancer worldwide. Surgery is the main treatment option for early disease; however, a relevant proportion of CRC patients relapse. Here, variations among preoperative and postoperative serum metabolomic fingerprint of CRC patients were studied, and possible associations between metabolic variations and cancer relapse were explored. Methods: A total of 41 patients with stage I-III CRC, planned for radical resection, were enrolled. Serum samples, collected preoperatively (t0) and 4–6 weeks after surgery before the start of any treatment (t1), were analyzed via NMR spectroscopy. NMR data were analyzed using multivariate and univariate statistical approaches. Results: Serum metabolomic fingerprints show differential clustering between t0 and t1 (82–85% accuracy). Pyruvate, HDL-related parameters, acetone, and 3-hydroxybutyrate appear to be the major players in this discrimination. Eight out of the 41 CRC patients enrolled developed cancer relapse. Postoperative, relapsed patients show an increase of pyruvate and HDL-related parameters, and a decrease of Apo-A1 Apo-B100 ratio and VLDL-related parameters. Conclusions: Surgery significantly alters the metabolomic fingerprint of CRC patients. Some metabolic changes seem to be associated with the development of cancer relapse. These data, if validated in a larger cohort, open new possibilities for risk stratification in patients with early-stage CRC.

The prevalence of DNA microsatellite instability in anaplastic thyroid carcinoma - systematic review and discussion of current therapeutic options

INTRODUCTION

Anaplastic thyroid carcinoma is a rare, rapidly progressing, highly aggressive thyroid malignancy. Responses to immune checkpoint inhibitors in mismatch repair-deficient/microsatellite instability-high tumours of other locations have shown promising results, and with the extended approval of the PD-1 receptor inhibitor pembrolizumab by the Food and Drug Administration, also anaplastic thyroid cancer (ATC) requires analysis for microsatellite instability (MSI) status.

MATERIAL AND METHODS

Systematic research for relevant literature was conducted in different databases. Prevalence, detection methods, and the potential prognostic/predictive value of MSI in view of the available targeted therapies were of special focus.

RESULTS

Selected citations revealed the prevalence of MSI in 7.4%, with mutations in the MSH2 gene (33%) being the most frequent, followed by MSH6 (25%) and MLH1 (16.7%) occurring in the following combinations: MLH1-MSH2 (8.3%), MSH2-MSH6 (8.3%), and MLH3-MSH5 (8.3%). No mutations in the PMS2 gene were reported. Sixty-six co-mutations in 9 cases were found, with TP53 (88.9%), NF1 (44.4 %), ATM (33.3%), and RB1 (33.3%) being the most frequent. No RAS mutations were noted. Survival ranged between 2.8 and 48 months, and patient age varied between 49 and 84 years. There are insufficient and heterogenous data concerning the predictive or prognostic value of mismatch repair-deficient/microsatellite instability status.

CONCLUSIONS

Tumour molecular profiling is fundamental in ATC for predictive, prognostic, as well as therapeutic reasons, and analysis of MSI status is strongly suggested because a small subgroup show the MSI signature and might profit from recently approved targeted therapies.

Occurrence of High Microsatellite-Instability/Mismatch Repair Deficiency in Nearly 2,000 Human Adenocarcinomas of the Gastrointestinal Tract, Pancreas, and Bile Ducts: A Study From a Large German Comprehensive Cancer Center

INTRODUCTION

Knowledge of the high microsatellite-instability (MSI-H)/mismatch repair deficiency (MMRd) status is of increasing interest for personalized neoadjuvant or adjuvant therapy planning. Only a few studies are available on MSI-H distribution in the Northern European Caucasian patient population. In this study, we focused on a large cohort of tumors of the upper gastrointestinal tract.

MATERIALS AND METHODS

Surgical material from a total of 1,965 patients was analyzed for MSI-H/MMRd status (including 1,267 carcinomas of the esophagus or stomach). All tumors were analyzed with an internationally recommended immunohistochemical panel consisting of four antibodies (MLH1, MSH2, PMS2, and MSH6). The results were molecularly objectified.

RESULTS

Adenocarcinomas with MSI-H/MMRd were detected with the following distribution: esophagus (1.4%), stomach (8.3%), small intestine (18.2%), large intestine (8.5%), intrahepatic bile ducts (1.9%), and pancreas (0%). In case of gastric tumors with MSI-H/MMRd, neoadjuvant therapy did not influence the prognosis of patients (p = 0.94). Within all tumor entities with MSI-H/MMRd, patients with a UICC stage 4 were also represented. In this advanced stage, 11.7% of patients with MSS tumors were diagnosed compared to 0.5% of patients with MSI-H tumors relative to the entire tumor collective.

DISCUSSION

In this study, the proportion of MSI-H/MMRd tumors in the stomach is smaller than would have been expected in knowledge of the data published by TCGA or AGRC. Negative prognostic effects regarding MSI-H status and neoadjuvant therapy as described by the MAGIC study group were not seen in our cohort. The extent to which the MSI-H/MMRd status should be known for neoadjuvant therapy planning must be clarified in prospective studies in the future. At present, there is no convincing data to dispense the neoadjuvant therapy for gastric carcinoma. Due to the very convincing, positive data regarding the response rates of MSI-H tumors to treatment with PD1/PD-L1 inhibitors, every metastatic carcinoma of the gastrointestinal tract should be tested for its MSI-H status.

Decreased mean platelet volume is associated with microsatellite instability in colorectal cancer: A propensity score-matched analysis

BACKGROUND

Patients with microsatellite instability-high (MSI-H) colorectal cancer (CRC) generally have a better prognosis and a more effective immune response than patients with microsatellite stable (MSS) CRC. Moreover, activated platelets play a crucial role in modulating innate immune cells. Mean platelet volume (MPV) is an indicator of platelet activation. This study is to examine the association between MPV and MSI status in CRC.

METHODS

We collected the clinical and pathological variables of 424 CRC patients diagnosed at the Harbin Medical University Cancer Hospital from January 2018 to December 2018. Associations between MPV levels and MSI status were examined. Propensity score matching (PSM) was performed to reduce the possibility of selection bias.

RESULTS

424 CRC patients were divided into low-MPV group and high-MPV group according to the optimal cut-off value of MPV. 131 high-MPV patients were matched to low-MPV counterparts in a 1:1 ratio by propensity score matching. As MPV levels increased, the percentage of patients with MSI-H reduced. Furthermore, compared with MSS group, the MSI-H group had a significantly lower MPV levels (p= 0.003 after matching). In addition, logistic regression analysis identified reduced MPV as an independent risk factor for MSI-H in CRC patients after controlling for other potential parameters.

CONCLUSION

Lower MPV is associated with MSI-H subtype of CRC. Further study on MPV in MSI-H CRC is warranted.

Microsatellite Instability in Sporadic Colorectal Malignancy: A Pilot Study from Northern India

BACKGROUND

Three molecular pathways are described as the genetic basis of colorectal tumorigenesis. Among these, microsatellite instability (MSI) has shown greatest promise in serving as a biomarker to determine disease aggression by tumour biology, recurrence, and response to chemotherapy.

METHODOLOGY

This prospective observational pilot study included patients of colorectal cancers, in a population subset coming to a tertiary care hospital in northern India, who were operated with curative or palliative intent over a period of one year and followed up for a maximum of 55 months. The post-operative pathological assessment was done for MSI status using PCR technique, and an attempt was made to evaluate its correlation with conventional clinical and histological parameters, early recurrences, disease-free survival and overall survival in comparison to MSS type tumours in sporadic cases of colorectal malignancies.

RESULTS

Out of 38 patients of colorectal cancer, 26 were included in the study. Male to female ratio was 7:6 (n=14:12). Mean age of presentation was 48±14.2 years. Incidence of MSI was n=4 (15.4%). On subgroup analysis, age of presentation (p=0.044) and evidence of perineural invasion (p=0.017) was found to have significant statistical association with MSI tumour biology. Recurrence was seen in seven of the seventeen patients who previously had no synchronous or metastatic disease (41.2%). The mean disease-free survival for MSS was 21.32 months and was 25.25 months for MSI group which was statistically insignificant (p = 0.277). Out of four MSI tumour biology patients one was alive and without recurrence at 47 months. While the other two were alive and without recurrence till 27 months of follow-up.   Conclusion: Age and perineural invasion showed statistically significant association with MSI tumour biology. Due to the small sample size statistical significance was not established with site, recurrence rate, DFS and OS.

Computed Tomography-Based Radiomics Model to Preoperatively Predict Microsatellite Instability Status in Colorectal Cancer: A Multicenter Study

Objectives

To establish and validate a combined radiomics model based on radiomics features and clinical characteristics, and to predict microsatellite instability (MSI) status in colorectal cancer (CRC) patients preoperatively.

Methods

A total of 368 patients from four hospitals, who underwent preoperative contrast-enhanced CT examination, were included in this study. The data of 226 patients from a single hospital were used as the training dataset. The data of 142 patients from the other three hospitals were used as an independent validation dataset. The regions of interest were drawn on the portal venous phase of contrast-enhanced CT images. The filtered radiomics features and clinical characteristics were combined. A total of 15 different discrimination models were constructed based on a feature selection strategy from a pool of 3 feature selection methods and a classifier from a pool of 5 classification algorithms. The generalization capability of each model was evaluated in an external validation set. The model with high area under the curve (AUC) value from the training set and without a significant decrease in the external validation set was final selected. The Brier score (BS) was used to quantify overall performance of the selected model.

Results

The logistic regression model using the mutual information (MI) dimensionality reduction method was final selected with an AUC value of 0.79 for the training set and 0.73 for the external validation set to predicting MSI. The BS value of the model was 0.12 in the training set and 0.19 in the validation set.

Conclusion

The established combined radiomics model has the potential to predict MSI status in CRC patients preoperatively.

Loss of CDX-2 expression is an independent poor prognostic biomarker in patients with early-stage deficient mismatch repair colorectal cancer

AIM

To investigate the clinicopathological factors, molecular features, and prognostic implications associated with loss of Caudal-related homeobox transcription factor 2 (CDX-2) expression in colorectal cancer (CRC) patients.

METHODS

Immunohistochemistry for CDX-2 expression was performed on formalin-fixed, paraffin-embedded primary CRC tissue samples from 449 patients. Correlation between CDX-2 expression and clinicopathological and molecular characteristics was evaluated. Univariate and multivariate survival analyses were performed to determine the prognostic value of loss of CDX-2 expression.

RESULTS

Of 449 patients, 84% were stage I-III. CDX-2-negative expression was identified in 18 of 441 (4.1%) patients. Loss of CDX-2 expression was more commonly found in patients with right-sided tumors rather than left-sided tumors (odds ratio [OR] = 3.57; p = 0.009), deficient mismatch repair (dMMR) compared to proficient MMR (pMMR) (OR = 3.7; p = 0.012), and BRAF mutation compared to BRAF wild type (OR = 8.06; p = 0.002). Univariate analysis revealed that stage I-III CRC patients with loss of CDX-2 expression had significantly worse overall survival (OS) and disease-free survival (DFS) than those with positive CDX-2 expression (5-year OS = 33.3% vs. 74.6%, respectively; p < 0.001, and 5-year DFS: 42.9% vs. 69.5%, respectively; p = 0.004). Loss of CDX-2 expression remained significantly associated with worse OS compared to positive CDX-2 expression in multivariate analysis (hazard ratio [HR] = 2.4; 95% confidence interval [CI], 1.12-5.11; p = 0.023).

CONCLUSIONS

Loss of CDX-2 expression was found to be associated with right-sided tumor, dMMR status, and BRAF mutation. Moreover, loss of CDX-2 expression is a poor prognostic factor for OS in stage I-III, even among patients with dMMR tumors.

A Serum Metabolomics Classifier Derived from Elderly Patients with Metastatic Colorectal Cancer Predicts Relapse in the Adjuvant Setting

Simple Summary

Around 30–40% of patients with early stage colorectal cancer (eCRC) experience relapse after surgery. Current recommendations for adjuvant therapy are based on suboptimal risk-stratification tools. In elderly patients, risk of relapse assessment is particularly important to ultimately avoid unnecessary chemotherapy-related toxicity in this frailer population. Serum metabolomics via NMR spectroscopy may improve risk stratification by identifying patients with residual micrometastases after surgery and thus at higher risk of relapse. We evaluated the serum metabolomic fingerprints of 94 elderly patients with eCRC (65 relapse free and 29 relapsed), and of 75 elderly patients with metastatic disease. Metabolomics efficiently discriminated patients with relapse-free eCRC from those with metastatic disease, correctly predicting relapse in 69% of relapsed eCRC patients. The metabolomic score was strongly and independently associated with prognosis. Our data suggest metabolomics as a valid addition to standard tools to refine risk stratification for eCRC and warrant further investigation.

Abstract

Adjuvant treatment for patients with early stage colorectal cancer (eCRC) is currently based on suboptimal risk stratification, especially for elderly patients. Metabolomics may improve the identification of patients with residual micrometastases after surgery. In this retrospective study, we hypothesized that metabolomic fingerprinting could improve risk stratification in patients with eCRC. Serum samples obtained after surgery from 94 elderly patients with eCRC (65 relapse free and 29 relapsed, after 5-years median follow up), and from 75 elderly patients with metastatic colorectal cancer (mCRC) obtained before a new line of chemotherapy, were retrospectively analyzed via proton nuclear magnetic resonance spectroscopy. The prognostic role of metabolomics in patients with eCRC was assessed using Kaplan–Meier curves. PCA-CA-kNN could discriminate the metabolomic fingerprint of patients with relapse-free eCRC and mCRC (70.0% accuracy using NOESY spectra). This model was used to classify the samples of patients with relapsed eCRC: 69% of eCRC patients with relapse were predicted as metastatic. The metabolomic classification was strongly associated with prognosis (p-value 0.0005, HR 3.64), independently of tumor stage. In conclusion, metabolomics could be an innovative tool to refine risk stratification in elderly patients with eCRC. Based on these results, a prospective trial aimed at improving risk stratification by metabolomic fingerprinting (LIBIMET) is ongoing.

Revealing the developmental dynamics in male strobilus transcriptome of Gnetum luofuense using nanopore sequencing technology

Gnetum is a pantropical distributed gymnosperm genus. As being dioecious, Gnetum species apply female and male strobili to attract and provide nutrition to insect pollinators. Due to its unique gross morphology, a Gnetum male strobilus receives much attention in previous taxonomic and evolutionary studies. However, underlying molecular mechanisms that control male strobilus development and pollination adaptation have not been well studied. In the present study, nine full-length transcriptomes were sequenced from three developmental stages of the G. luofuense male strobili using Oxford Nanopore Technologies. In addition, weighted gene co-expression network analysis (WGCNA), and RT-qPCR analysis were performed. Our results show that a total of 3138 transcription factors and 466 long non-coding RNAs (lncRNAs) were identified, and differentially expressed lncRNAs and TFs reveal a dynamic pattern during the male strobilus development. Our results show that MADS-box and Aux/IAA TFs were differentially expressed at the three developmental stages, suggesting their important roles in the regulation of male strobilus development of G. luofuense. Results of WGCNA analysis and annotation of differentially expressed transcripts corroborate that the male strobilus development of G. luofuense is closely linked to plant hormone changes, photosynthesis, pollination drop secretion and reproductive organ defense. Our results provide a valuable resource for understanding the molecular mechanisms that drive organ evolution and pollination biology in Gnetum.

Mismatch repair deficiency and clinicopathological characteristics in endometrial carcinoma: a systematic review and meta-analysis

Background

Loss of mismatch repair (MMR) occurs frequently in endometrial carcinoma (EC) and is an important prognostic marker. However, the frequency of MMR deficiency (D-MMR) in EC remains inconclusive. This systematic review and meta-analysis addressed this inconsistency and evaluated related clinicopathology.

Methods

Electronic databases were searched for articles: PubMed, Science Direct, Web of Science, EMBASE, and the Wiley Online Library. Data were extracted from 25 EC studies of D-MMR to generate a clinical dataset of 7,459 patients. A random-effects model produced pooled estimates of D-MMR EC frequency with 95% confidence interval (CI) for meta-analysis.

Results

The overall pooled proportion of D-MMR was 24.477% (95% CI, 21.022 to 28.106) in EC. The Lynch syndrome subgroup had 22.907% pooled D-MMR (95% CI, 14.852 to 32.116). D-MMR was highest in type I EC (25.810) (95% CI, 22.503 to 29.261) compared to type II (13.736) (95% CI, 8.392 to 20.144). Pooled D-MMR was highest at EC stage and grades I–II (79.430% and 65.718%, respectively) and lowest in stages III–IV and grade III (20.168% and 21.529%). The pooled odd ratios comparing D-MMR to proficient MMR favored low-stage EC disease (1.565; 0.894 to 2.740), lymphovascular invasion (1.765; 1.293 to 2.409), and myometrial invasion >50% (1.271; 0.871 to 1.853).

Conclusions

Almost one-quarter of EC patients present with D-MMR tumors. The majority has less aggressive endometrioid histology. D-MMR presents at lower tumor stages compared to MMR-proficient cases in EC. However other metastatic parameters are comparatively higher in the D-MMR disease setting.

Assessment of mismatch repair deficiency, CDX2, beta-catenin and E-cadherin expression in colon cancer: molecular characteristics and impact on prognosis and survival - an immunohistochemical study

Microsatellite instability (MSI) or the deficiency of mismatch repair (MMR) proteins is one of the molecular pathways of colorectal tumorigenesis and may have important clinical implications in predicting the treatment response. We evaluated the relationship between clinicopathological features and MMR proteins [mutL homologue 1 (MLH1), mutS homologue 2 (MSH2), mutS homologue 6 (MSH6), postmeiotic segregation increased 2 (PMS2)], adhesion molecules (E-cadherin, beta-catenin) and caudal-type homeobox 2 (CDX2) in 31 patients with colon adenocarcinoma, using immunohistochemistry. We also aimed to assess the prognostic value of the studied proteins. MLH1 loss was correlated to PMS2 loss (p=0.006) and MSH2 loss (p=0.023); MSH2 loss was significantly associated to MSH6 loss (p=0.011). Tumors with MSH6 loss, together with tumors with PMS2 loss, covered all the patients with MSI status. We found a significant correlation between MSI tumors and mucinous histological type (p=0.03), but no significant associations with other clinicopathological features or with survival rate. There was a significant correlation between E-cadherin expression and differentiation degree (p=0.018) and between beta-catenin expression and lymph node invasion (p=0.046). No significant association between CDX2 loss and any clinical or pathological features was found (p>0.05). No significant differences were identified in overall survival according to E-cadherin, beta-catenin or CDX2 expression (p>0.05). In our study, PMS2 loss was significantly correlated with CDX2 loss (p=0.03). In conclusion, the molecular analysis of biological markers for colon cancer may be important for patient stratification, in order to select the optimal treatment algorithm. Our results suggest that probably the double panel (MSH6 and PMS2) is enough to detect the MSI status, instead of using the quadruple panel.

Molecular Oncology in Management of Colorectal Cancer

Colorectal cancers are the third most common cancers in the world. Management of both primary and metastatic colorectal cancers has evolved over the last couple of decades. Extensive research in molecular oncology has helped us understand and identify these complex intricacies in colorectal cancer biology and disease progression. These advances coupled with improved knowledge on various mutations have helped develop targeted chemotherapeutics and has allowed planning an effective treatment regimen in this era of immunotherapy with precision. The diverse chemotherapeutic and biological agents at our disposal can make decision making a very complex process. Molecular profile, including CIN, RAS, BRAF mutations, microsatellite instability, ctDNA, and consensus molecular subtypes, are some of the important factors which are to be considered while planning an individualized treatment regimen. This article summarizes the current status of molecular oncology in the management of colorectal cancer and should serve as a practical guide for the clinical team.

Evaluation of the Role of Circulating Tumor Cells and Microsatellite Instability Status in Predicting Outcome of Advanced CRC Patients

Colorectal cancer (CRC) remains one of the leading causes of cancer-related death due to its high metastatic potential. This study aimed to investigate the detection and heterogeneity of circulating tumor cells (CTCs) and the microsatellite instability (MSI) status in advanced CRC patients prior to any systemic front-line treatment. Peripheral whole blood was obtained from 198 patients. CTCs were detected using double immunofluorescence and a real time-polymerase chain reaction assay; whereas MSI status was evaluated using fragment analysis. Median age of the patients was 66 years, 63.1% were males, 65.2% had a colon/sigmoid tumor location and 90.4% had a good performance status (PS). MSI-High status was detected in 4.9% of the patients; 33.3%, 56.1% and 8.6% patients had at least one detectable CEACAM5⁺/EpCAM⁺, CEACAM5⁺/EpCAM^- and CEACAM5^-/EpCAM⁺ CTC, respectively, and 9.1% of the patients had CEACAM5mRNA-positive CTCs. Following multivariate analysis, age, PS and MSI were confirmed as independent prognostic factors for decreased time to progression, whereas age, PS and CTC presence were confirmed as independent prognostic factors for decreased overall survival. In conclusion, our data support the use of CEACAM5 as a dynamic adverse prognostic CTC biomarker in patients with metastatic CRC and MSI-High is considered an unfavorable prognostic factor in metastatic CRC patient tumors.

Microsatellite instability and sensitivity to fluoropyrimidine and oxaliplatin containing first-line chemotherapy in metastatic colorectal cancer

OBJECTIVES

To examine the effect of microsatellite instability (MSI) on the outcome of fluoropyrimidine and oxaliplatin containing first-line chemotherapy in metastatic colorectal cancer (mCRC).

METHODS

Patients with mCRC and treated with fluoropyrimidine/oxaliplatin first-line chemotherapy were included in our study. Demographic data, tumour characteristics, chemotherapy regimens, treatment responses and progression-free survival (PFS) were collected from medical records. The MSI analysis was performed using fluorescence-based PCR, and divided into MSI-high (MSI-H) and MSI-low (MSI-L)/microsatellite stable (MSS). Statistical analysis used Kaplan-Meier method, log-rank test and multivariate Cox model.

RESULTS

From 1 January 2015 to 1 May 2016, a total of 192 patients with mCRC were included in our study. Among these, 14 (7.29%) exhibited MSI-H and 178 (92.71%) were MSI-L/MSS. The objective response rate (p=0.79), disease control rate (p=0.22) and PFS (p=0.22) of fluoropyrimidine/oxaliplatin first-line chemotherapy were not significantly different between MSI-H and MSI-L/MSS tumours. But MSI-H tumours had a trend to better disease control rate (71.43% vs 54.49%) and PFS (6.50 m vs 5.40 m) than MSI-L/MSS tumours. Multivariate analysis indicated that MSI was not a predictive factor for PFS (p=0.18).

CONCLUSION

The effect of fluoropyrimidine/oxaliplatin first-line chemotherapy was not significantly different between MSI-H and MSI-L/MSS tumours. However, MSI-H tumours tended to have better disease control rate and PFS.

Surgical approach for rectal cancer: A network meta-analysis comparing open, laparoscopic, robotic and transanal TME approaches

BACKGROUND

The optimal approach for total mesorectal excision (TME) of rectal cancer remains controversial.

AIM

To compare short- and long-term outcomes after open (OpTME), laparoscopic (LapTME), robotic (RoTME) and transanal TME (TaTME).

METHODS

A systematic search of electronic databases was performed up to January 1, 2020 for randomized controlled trials (RCTs) comparing at least 2 TME strategies. A Bayesian arm-based random effect network meta-analysis (NMA) was performed, specifically, a mixed treatment comparison (MTC).

RESULTS

30 RCTs (and six updates) of 5586 patients with rectal cancer were included. No significant differences were identified in recurrence rates or survival rates. Operating time was shorter with OpTME (surface under the cumulative ranking curve [SUCRA] 0.96) compared to LapTME, RoTME and TaTME. Although OpTME was associated with the most blood loss (SUCRA 0.90) and had a slower recovery with increased length of stay (SUCRA 0.90) compared to the minimally invasive techniques, there was no difference in postoperative morbidity. OpTME was associated with a more complete TME specimen compared to LapTME (Risk Ratio [RR] 1.05, 95% Credible Interval [CrI] 1.01, 1.11), and TaTME had less involved CRMs (RR 0.173, 95% CrI 0.02, 0.76) versus LapTME. There were no differences between the modalities in terms of deep TME defects, DRM distance, or lymph node yield.

CONCLUSIONS

While OpTME was the most effective TME modality for short term histopathological resection quality, there was no difference in long-term oncologic outcomes. Minimally invasive approaches enhance postoperative recovery, at the cost of longer operating times. Technique selection should be based on individual tumour characteristics and patient expectations, as well as surgeon and institutional expertise.

Characterization of Chilean patients with sporadic colorectal cancer according to the three main carcinogenic pathways: Microsatellite instability, CpG island methylator phenotype and Chromosomal instability

Molecular classification of colorectal cancer is difficult to implement in clinical settings where hundreds of genes are involved, and resources are limited. This study aims to characterize the molecular subtypes of patients with sporadic colorectal cancer based on the three main carcinogenic pathways microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and chromosomal instability (CIN) in a Chilean population. Although several reports have characterized colorectal cancer, most do not represent Latin-American populations. Our study includes 103 colorectal cancer patients who underwent surgery, without neoadjuvant treatment, in a private hospital between 2008 and 2017. MSI, CIN, and CIMP status were assessed. Frequent mutations in KRAS, BRAF, and PIK3CA genes were analyzed by Sanger sequencing, and statistical analysis was performed by Fisher's exact and/or chi-square test. Survival curves were estimated with Kaplan-Meier and log-rank test. Based on our observations, we can classify the tumors in four subgroups, Group 1: MSI-high tumors (15%) are located in the right colon, occur at older age, and 60% show a BRAF mutation; Group 2: CIN-high tumors (38%) are in the left colon, and 26% have KRAS mutations. Group 3: [MSI/CIN/CIMP]-low/negative tumors (30%) are left-sided, and 39% have KRAS mutations; Group 4: CIMP-high tumors (15%) were more frequent in men and left side colon, with 27% KRAS and 7% presented BRAF mutations. Three percent of patients could not be classified. We found that CIMP-high was associated with a worse prognosis, both in MSI-high and MSI stable patients (p = 0.0452). Group 3 (Low/negative tumors) tend to have better overall survival compared with MSI-high, CIMP-high, and CIN-high tumors. This study contributes to understanding the heterogeneity of tumors in the Chilean population being one of the few characterizations performed in Latin-America. Given the limited resources of these countries, these results allow to improve molecular characterization in Latin-American colorectal cancer populations and confirm the possibility of using the three main carcinogenic pathways to define therapeutic strategies.

Targeted next generation sequencing of MLH1-deficient, MLH1 promoter hypermethylated, and BRAF/RAS-wild-type colorectal adenocarcinomas is effective in detecting tumors with actionable oncogenic gene fusions

Oncogenic gene fusions represent attractive targets for therapy of cancer. However, the frequency of actionable genomic rearrangements in colorectal cancer (CRC) is very low, and universal screening for these alterations seems to be impractical and costly. To address this problem, several large scale studies retrospectivelly showed that CRC with gene fusions are highly enriched in groups of tumors defined by MLH1 DNA mismatch repair protein deficiency (MLH1d), and hypermethylation of MLH1 promoter (MLH1ph), and/or the presence of microsatellite instability, and BRAF/KRAS wild-type status (BRAFwt/KRASwt). In this study, we used targeted next generation sequencing (NGS) to explore the occurence of potentially therapeutically targetable gene fusions in an unselected series of BRAFwt/KRASwt CRC cases that displayed MLH1d/MLH1ph. From the initially identified group of 173 MLH1d CRC cases, 141 cases (81.5%) displayed MLH1ph. BRAFwt/RASwt genotype was confirmed in 23 of 141 (~16%) of MLH1d/MLH1ph cases. Targeted NGS of these 23 cases identified oncogenic gene fusions in nine patients (39.1%; CI95: 20.5%-61.2%). Detected fusions involved NTRK (four cases), ALK (two cases), and BRAF genes (three cases). As a secondary outcome of NGS testing, we identified PIK3K-AKT-mTOR pathway alterations in two CRC cases, which displayed PIK3CA mutation. Altogether, 11 of 23 (~48%) MLH1d/MLH1ph/BRAFwt/RASwt tumors showed genetic alterations that could induce resistance to anti-EGFR therapy. Our study confirms that targeted NGS of MLH1d/MLH1ph and BRAFwt/RASwt CRCs could be a cost-effective strategy in detecting patients with potentially druggable oncogenic kinase fusions.

CDX2 Loss With Microsatellite Stable Phenotype Predicts Poor Clinical Outcome in Stage II Colorectal Carcinoma

Current risk factors in stage II colorectal carcinoma are insufficient to guide treatment decisions. Loss of CDX2 has been shown to associate with poor clinical outcome and predict benefit for adjuvant chemotherapy in stage II and III colorectal carcinoma. The prognostic relevance of CDX2 in stage II disease has not been sufficiently validated, especially in relation to clinical risk factors, such as microsatellite instability (MSI) status, BRAF mutation status, and tumor budding. In this study, we evaluated the protein expression of CDX2 in tumor center and front areas in a tissue microarrays material of stage II colorectal carcinoma patients (n=232). CDX2 expression showed a partial or total loss in respective areas in 8.6% and 10.9% of patient cases. Patients with loss of CDX2 had shorter disease-specific survival when scored independently either in tumor center or tumor front areas (log rank P=0.012; P=0.012). Loss of CDX2 predicted survival independently of other stage II risk factors, such as MSI status and BRAF mutation status, pT class, and tumor budding (hazard ratio=5.96, 95% confidence interval=1.55-22.95; hazard ratio=3.70, 95% confidence interval=1.30-10.56). Importantly, CDX2 loss predicted inferior survival only in patients with microsatellite stable, but not with MSI-high phenotype. Interestingly, CDX2 loss associated with low E-cadherin expression, tight junction disruption, and high expression of ezrin protein. The work demonstrates that loss of CDX2 is an independent risk factor of poor disease-specific survival in stage II colorectal carcinoma. Furthermore, the study suggests that CDX2 loss is linked with epithelial-to-mesenchymal transition independently of tumor budding.

Low BRCA2 expression predicts poor prognoses in patients with rectal cancer receiving chemoradiotherapy

OBJECTIVE

Neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgery is now the standard care for patients with advanced rectal cancer. Because a certain proportion of these patients have poor response to CCRT, the risk stratification of survival outcomes needs to be investigated. DNA repair responses in tumor cells can regulate malignant potential and therapy resistance. In this study, we analyzed the clinical significance of principal DNA repair effectors in patients with rectal cancer.

METHODS

We applied data mining for DNA repair pathways in a published transcriptome for rectal cancer cases, and identified that tumors with BRCA2 downregulation correlated with poor response to CCRT. We next examined BRCA2 expression by using immunohistochemistry staining in tumor tissues of 172 patients with rectal cancer. The correlation between BRCA2 expression levels and clinical variables was further analyzed in this rectal cancer cohort.

RESULTS

Among clinical and pathological factors, low BRCA2-expression was significantly correlated with higher pre-treatment (Tx) tumor status (P = .013), post-Tx tumor (P < .001) and nodal status (P = .044), vascular invasion (P = .008), and poor tumor regression grades (P < .001). In analyses of survival outcomes, patients with low BRCA2-expression were associated with shorter local recurrence-free survival (LRFS; P = .0005) and disease-specific survival (P = .0269). Multivariate analyses confirmed the independent prognostic value of low BRCA2-expression for shorter LRFS (P = .045, hazard ratio = 4.695).

CONCLUSION

Low BRCA2-expression is a significant predictor for tumors in advanced stages, poor response to CCRT, and shorter survivals in patients with rectal cancer. Poly (adenosine diphosphate-ribose) polymerase inhibitors targeting DNA repair response in cells have demonstrated clinical efficacy in BRCA2-mutated patients with cancer. Further studies evaluating the efficacy of CCRT combined with these inhibitors in low BRCA2-expressing rectal cancers are encouraged.

Predicting the effect of 5-fluorouracil-based adjuvant chemotherapy on colorectal cancer recurrence: A model using gene expression profiles

It is critical to identify patients with stage II and III colorectal cancer (CRC) who will benefit from adjuvant chemotherapy (ACT) after curative surgery, while the only use of clinical factors is insufficient to predict this beneficial effect. In this study, we performed genetic algorithm (GA) to select ACT candidate genes, and built a predictive model of support vector machine (SVM) using gene expression profiles from the Gene Expression Omnibus database. The model contained four ACT candidate genes (EDEM1, MVD, SEMA5B, and WWP2) and TNM stage (stage II or III). After using Subpopulation Treatment Effect Pattern Plot to determine the optimal cutoff value of predictive scores, the validated patients from The Cancer Genome Atlas database can be divided into the predictive ACT-benefit/-futile groups. Patients in the predictive ACT-benefit group with 5-fluorouracil (5-Fu)-based ACT had significantly longer relapse-free survival (RFS) compared to those without ACT (P = .015); However, the difference in RFS in the predictive ACT-futile group was insignificant (P = .596). The multivariable analysis found that the predictive groups were significantly associated with the effect of ACT (P_interaction  = .011). Consequently, we developed a predictive model based on the SVM and GA algorithm which was further validated to define patients who benefit from ACT on recurrence.

Epidemiology of Microsatellite Instability High (MSI-H) and Deficient Mismatch Repair (dMMR) in Solid Tumors: A Structured Literature Review

Background. Given limited data on the epidemiology of MSI-H and dMMR across solid tumors (except colorectal cancer (CRC)), the current study was designed to estimate their prevalence. Materials and Methods. A structured literature review identified English language publications that used immunohistochemistry (IHC) or polymerase chain replication (PCR) techniques. Publications were selected for all tumors except CRC using MEDLINE, EMBASE, and Cochrane databases and key congresses; CRC and pan-tumor genomic publications were selected through a targeted review. Meta-analysis was performed to estimate pooled prevalence of MSI-H/dMMR across all solid tumors and for selected tumor types. Where possible, prevalence within tumor types was estimated by disease stages. Results. Of 1,176 citations retrieved, 103 and 48 publications reported prevalence of MSI-H and dMMR, respectively. Five pan-tumor genomic studies supplemented the evidence base. Tumor types with at least 5 publications included gastric (n = 39), ovarian (n = 23), colorectal (n = 20), endometrial (n = 53), esophageal (n = 6), and renal cancer (n = 8). Overall MSI-H prevalence (with 95% CI) across 25 tumors was based on 90 papers (28,213 patients) and estimated at 14% (10%–19%). MSI-H prevalence among Stage 1/2 cancers was estimated at 15% (8%–23%); Stages 3 and 4 prevalence was estimated at 9% (3%–17%) and 3% (1%–7%), respectively. Overall, dMMR prevalence across 13 tumor types (based on 54 papers and 20,383 patients) was estimated at 16% (11%–22%). Endometrial cancer had the highest pooled MSI-H and dMMR prevalence (26% and 25% all stages, respectively). Conclusions. This is the first comprehensive attempt to report pooled prevalence estimates of MSI-H/dMMR across solid tumors based on published data. Prevalence determined by IHC and PCR was generally comparable, with some variations by cancer type. Late-stage prevalence was lower than that in earlier stages.

Outcomes for Metastatic Colorectal Cancer Based on Microsatellite Instability: Results from the South Australian Metastatic Colorectal Cancer Registry

BACKGROUND

Microsatellite instability (MSI) is the molecular marker for DNA mismatch repair deficiency (dMMR) in colorectal cancer (CRC) and has been associated with better survival outcomes in early stage disease. In metastatic CRC (mCRC), outcomes for patients with MSI are less clear. There is evolving evidence that treatment pathways for MSI CRC should include programmed-death 1 (PD-1) antibodies.

OBJECTIVE

An analysis was performed to explore the impact of MSI status on overall survival (OS) in mCRC.

PATIENTS AND METHODS

South Australian Metastatic CRC Registry data were analysed to assess patient characteristics and survival outcomes, comparing patients with MSI CRC with those whose tumours were microsatellite stable (MSS). Kaplan-Meier survival analysis was used to assess OS. Cox regression analysis was undertaken to assess the independence of MSI as a prognostic factor.

RESULTS

Of 4359 patients registered on the database, 598 (14%) had been tested for, and 62 (10.1%) of these patients had, demonstrable MSI. There were significantly higher rates of right-sided primary (p < 0.001), poorly differentiated pathology (p = 0.002), and BRAF V600E mutation (p < 0.001) in the MSI group. The MSI group were also less likely to receive chemotherapy (p < 0.001) or to have liver surgery, but more likely to be diagnosed at an early stage. The median overall survival was 9.5 months for those with MSI CRC versus 21.3 months for MSS CRC patients (p = 0.052). Cox regression analysis indicated that MSI was not an independent predictor of OS. Independent predictors of better OS included having liver surgery for metastasis, having chemotherapy, and being initially diagnosed at an early stage.

CONCLUSIONS

Only 14% of patients with mCRC were tested for MSI, and 1 in 10 were found to be MSI high. The clinical characteristics of MSI mCRC are in keeping with those previously reported. MSI in this population-based registry was associated with a numerically lower survival which did not attain statistical significance.

Perspectives on Treatment of Metastatic Colorectal Cancer with Immune Checkpoint Inhibitor Therapy

Despite lengthening survival, death rates from metastatic colorectal cancer (CRC) remain unacceptably high, with a bright spot being the demonstration of durable responses in patients with CRC who have mismatch repair-deficient (dMMR) and/or microsatellite instability-high (MSI-H) tumors and are treated with immune checkpoint inhibitor therapy. Nivolumab and pembrolizumab, as well as nivolumab in combination with low-dose ipilimumab-all checkpoint inhibitors-are currently approved by the U.S. Food and Drug Administration (FDA) for patients with MSI-H/dMMR metastatic CRC that progressed following treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. Nonetheless, there are a number of questions and considerations in the use of these checkpoint inhibitor therapies. Using a question-and-answer format, this review summarizes the scientific rationale for immune checkpoint inhibitor therapy in CRC, including the effects of tumor factors such as genetic aberrations and mutational load on the immune response, particularly in patients with MSI-H/dMMR disease. We discuss response patterns, response criteria, and immune-related adverse events using findings from published efficacy and safety data of immune checkpoint inhibitor therapy in metastatic CRC. We also discuss issues surrounding treatment sequencing, incorporating approved checkpoint inhibitors into the current treatment paradigm, and the multiple investigational strategies that may optimize immunotherapy for advanced CRC in the future, including novel combination therapies. IMPLICATIONS FOR PRACTICE: Colorectal cancer (CRC) is the third most common cancer in the U.S. Despite advances in chemotherapy, survival remains poor for patients with metastatic CRC. Certain immunotherapy agents have demonstrated long-lasting responses in previously treated patients with immune-responsive microsatellite instability-high/mismatch repair-deficient metastatic CRC, leading to U.S. Food and Drug Administration approval of the immune checkpoint inhibitors nivolumab (with or without low-dose ipilimumab) and pembrolizumab in this population. Combination therapy (e.g., nivolumab with low-dose ipilimumab) has demonstrated numerically higher response rates and improved long-term clinical benefit relative to anti-programmed death-1 monotherapy. Ongoing trials are evaluating immunotherapy in the broader CRC population and novel combinations to optimize immunotherapy for advanced CRC.

Association of DNA repair gene polymorphisms with colorectal cancer risk and treatment outcomes

Colorectal cancer (CRC) is the third most common carcinoma worldwide. Despite the progress in screening and treatment, CRC remains a leading cause of cancer-related mortality. Alterations to normal nucleic acid processing may drive neoplastic transformation of colorectal epithelium. DNA repair machinery performs an essential function in the protection of genome by reducing the number of genetic polymorphisms/variations that may drive carcinogenicity. Four essential DNA repair systems are known which include nucleotide excision repair (NER), base excision repair (BER), mismatch repair (MMR), and double-strand break repair (DSBR). Polymorphisms of DNA repair genes have been shown to influence the risk of cancer development as well as outcomes of treatment. Several studies demonstrated the association between genetic polymorphism of DNA repair genes and increased risk of CRC in different populations. In this review, we have summarized the impact of DNA repair gene polymorphisms on risk of CRC development and treatment outcomes. Advancements of the current understanding for the impact of DNA repair gene polymorphisms on the risk and treatment of CRC may support diagnostic and predictive roles in patients with CRC.

Clinicopathological features of Egyptian colorectal cancer patients regarding somatic genetic mutations especially in KRAS gene and microsatellite instability status: a pilot study

Background

Colorectal cancer (CRC) is the third most common cause of cancer-related deaths which contributes to a significant public health problem worldwide with 1.8 million new cases and almost 861,000 deaths in 2018 according to the World Health Organization. It exhibits 7.4% of all diagnosed cancer cases in the region of the Middle East and North Africa. Molecular changes that happen in CRCs are chromosomal instability, microsatellite instability (MSI), and CpG island methylator phenotype. The human RAS family (KRAS, NRAS, and HRAS) is the most frequently mutated oncogenes in human cancer appearing in 45% of colon cancers. Determining MSI status across CRCs offers the opportunity to identify patients who are likely to respond to targeted therapies such as anti-PD-1. Therefore, a method to efficiently determine MSI status for every cancer patient is needed.

Results

KRAS mutations were detected in 31.6% of CRC patients, namely in older patients (p = 0.003). Codons 12 and 13 constituted 5/6 (83.3%) and 1/6 (16.7%) of all KRAS mutations, respectively. We found three mutations G12D, G12C, and G13D which occur as a result of substitution at c.35G>A, c.34G>T, and c.38G>A and have been detected in 4/6 (66.6%), 1/6 (16.7%), and 1/6 (16.7%) patients, respectively. Eleven (57.9%) patients had microsatellite instability-high (MSI-H) CRC. A higher percentage of MSI-H CRC was detected in female patients (p = 0.048). Eight patients had both MSI-H CRC and wild KRAS mutation with no statistical significance was found between MSI status and KRAS mutation in these studied patients.

Conclusion

In conclusion, considering that KRAS mutations confer resistance to EGFR inhibitors, patients who have CRC with KRAS mutation could receive more tailored management by defining MSI status. MSI-high patients have enhanced responsiveness to anti-PD-1 therapies. Thus, the question arises as to whether it is worth investigating this association in the routine clinical setting or not. Further studies with a larger number of patients are needed to assess the impact of MSI status on Egyptian CRC care.

5-fluorouracil and other fluoropyrimidines in colorectal cancer: Past, present and future

5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for colorectal cancer (CRC) in the palliative and adjuvant settings. Over the past four decades, several modulation strategies including the implementation of 5-FU-based combination regimens and 5-FU pro-drugs have been developed and tested to increase the anti-tumor activity of 5-FU and to overcome the clinical resistance. Despite the encouraging progress in CRC therapy to date, the patients' response rates to therapy continue to remain low and the patients' benefit from 5-FU-based therapy is frequently compromised by the development of chemoresistance. Inter-individual differences in the treatment response in CRC patients may originate in the unique genetic and epigenetic make-up of each individual. The critical element in the current trend of personalized medicine is the proper comprehension of causes and mechanisms contributing to the low or lack of sensitivity of tumor tissue to 5-FU-based therapy. The identification and validation of predictive biomarkers for existing 5-FU-based and new targeted therapies for CRC treatment will likely improve patients' outcomes in the future. Herein we present a comprehensive review summarizing options of CRC treatment and the mechanisms of 5-FU action at the molecular level, including both anabolic and catabolic ways. The main part of this review comprises the currently known molecular mechanisms underlying the chemoresistance in CRC patients. We also focus on various 5-FU pro-drugs developed to increase the amount of circulating 5-FU and to limit toxicity. Finally, we propose future directions of personalized CRC therapy according to the latest published evidence.

RPL22L1 induction in colorectal cancer is associated with poor prognosis and 5-FU resistance

We have previously demonstrated that loss of the tumor suppressive activity of ribosomal protein (RP) RPL22 predisposes to development of leukemia in mouse models and aggressive disease in human patients; however, the role of RPL22 in solid tumors, specifically colorectal cancer (CRC), had not been explored. We report here that RPL22 is either deleted or mutated in 36% of CRC and provide new insights into its mechanism of action. Indeed, Rpl22 inactivation causes the induction of its highly homologous paralog, RPL22L1, which serves as a driver of cell proliferation and anchorage-independent growth in CRC cells. Moreover, RPL22L1 protein is highly expressed in patient CRC samples and correlates with poor survival. Interestingly, the association of high RPL22L1 expression with poor prognosis appears to be linked to resistance to 5-Fluorouracil, which is a core component of most CRC therapeutic regimens. Indeed, in an avatar trial, we found that human CRC samples that were unresponsive to 5-Fluorouracil in patient-derived xenografts exhibited elevated expression levels of RPL22L1. This link between RPL22L1 induction and 5-Fluorouracil resistance appears to be causal, because ectopic expression or knockdown of RPL22L1 in cell lines increases and decreases 5-Fluorouracil resistance, respectively, and this is associated with changes in expression of the DNA-repair genes, MGMT and MLH1. In summary, our data suggest that RPL22L1 might be a prognostic marker in CRC and predict 5-FU responsiveness.

Molecular mutation characteristics of mismatch and homologous recombination repair genes in gastrointestinal cancer

Gastrointestinal cancer is one of the most common types of cancer with high mortality rates. Mutations in several genes are reportedly involved in the progression of gastrointestinal cancer, including tumor protein 53 (TP53), APC regulator of WNT signaling pathway (APC), KRAS proto-oncogene GTPase (KRAS) and erb-b2 receptor tyrosine kinase 2 (ERBB2). Most notably, there are numerous mutations in DNA repair genes, including mismatch repair (MMR) and homologous recombination (HR) genes. The focus of the present study was to investigate the effects of MMR and HR gene mutations on genomic instability in gastrointestinal cancer. Using targeted capture and massively parallel genomic sequencing, 137 gastrointestinal cancer patients were analyzed for somatic single-nucleotide variants (SNVs) and insertion-deletion (indel) mutations in the exon regions of 183 cancer driver genes, including 4 MMR genes [MutL homolog MLH1, MLH2, MLH6 and PMS1 homolog 2, mismatch repair system component (PMS2)] and 15 HR genes [BRCA1 DNA repair associated (BRCA1), BRCA2 DNA repair associated (BRCA2), ATM serine/threonine kinase (ATM), phosphatase and tensin homolog, BLM RecQ like helicase, FA complementation group A, FA complementation group C, FA complementation group D2, FA complementation group E, FA complementation group F, FA complementation group G, nibrin, partner and localizer of BRCA2 and Werner syndrome RecQ like helicase]. A number of frequently mutated genes, including but not limited to, mechanistic target of rapamycin kinase, neurofibromin 1, APC and, in particular, DNA repair genes, including PMS2, ATM and BRCA2, were identified. Frequency analysis was performed based on the SNVs and indels in the 183 genes to indirectly indicate the relative status of genomic instability in each patient. Correlation analysis suggested that MMR and HR gene mutations directly affected the count of SNVs and indels. Overall, 56 of the gastrointestinal cancer patients (40%) were found to have an inactivation mutation (stopgain/frameshift/splicing) in one or more of the four MMR genes, whereas 112 patients (82%) harbored at least one HR gene inactivation mutation. In addition, patients with MMR or HR inactivation variants had more SNVs and indels compared with patients with no such mutations. No other clinical characteristics (including sex and age) appeared to have a statistically significant impact. Further analysis indicated that different MMR or HR genes exerted distinct effects on genomic instability. The results obtained in the current study may lay a foundation for investigations into the tumorigenic process and for the development of novel therapeutic strategies for the treatment of gastrointestinal cancer.

[Microsatellite instability : Review of methods and applications]

After introduction of the Bethesda microsatellite test panel demonstration of microsatellite instability (MSI) and/or loss of mismatch repair proteins (MMRD) was primarily used as a marker for cancer predisposition of Lynch syndrome (LS, previous: HNPCC). Nowadays MSI/MMRD has become an important biomarker to predict therapy response to checkpoint immunotherapies. MSI can be determined either by polymerase chain reaction (PCR)-based technologies with or without specification of fragment sizes or next generation sequencing (NGS) methods. Depending on the individual tumor entities, these test methods are used differently. Currently, MSI/MMRD is a tumor biomarker which covers a broad spectrum of indications in tumor pathology, especially in colorectal, endometrial and gastric cancer. In advanced carcinomas, MSI is an established predictor of therapy response to checkpoint-directed immunotherapies.

Detecting genetic hypermutability of gastrointestinal tumor by using a forensic STR kit

Growing evidence suggests that somatic hypermutational status and programmed cell death-1 overexpression are potential predictive biomarkers indicating treatment benefits from immunotherapy using immune checkpoint inhibitors. However, biomarker-matched trials are still limited, and many of the genomic alterations remain difficult to target. To isolate the potential somatic hypermutational tumor from microsatellite instability low/microsatellite stability (MSI-L/MSS) cases, we employed two commercial kits to determine MSI and forensic short tandem repeat (STR) alternations in 250 gastrointestinal (GI) tumors. Three types of forensic STR alternations, namely, allelic loss, Aadd, and Anew, were identified. 62.4% (156/250) of the patients with GI exhibited STR alternation, including 100% (15/15) and 60% (141/235) of the microsatellite high instability and MSI-L/MSS cases, respectively. 30% (75/250) of the patients exhibited STR instability with more than 26.32% (26.32%-84.21%) STR alternation. The cutoff with 26.32% of the STR alternations covered all 15 MSI cases and suggested that it might be a potential threshold. Given the similar mechanism of the mutations of MSI and forensic STR, the widely used forensic identifier STR kit might provide potential usage for identifying hypermutational status in GI cancers.

Deficient mismatch repair as a prognostic marker in stage II colon cancer patients

BACKGROUND

A number of reports have evaluated the relationship between deficient DNA mismatch repair (dMMR) and colorectal cancer prognosis. Unfortunately, the exact prognostic role of dMMR has not been clearly established due to contradictory results. This study aims to determine the prognostic impact of dMRR in stage II colon cancer patients only. The appropriate identification of high-risk stage II colon cancers is of paramount importance in the selection of patients who may benefit from adjuvant treatment after surgery.

METHODS

Four hundred and fifty-two patients with curative resection of stage II colon cancer were included. Hospital records were used as data source, providing clinical, surgical, pathology, oncology and follow-up information for statistical analysis focusing on overall survival (OS) and time to progression (TTP). Mismatch repair status was determined by immunohistochemistry. Patient survival was followed-up for a mean of 77·35 months.

RESULTS

dMMR was detected in 93 of 452 patients (20·6%). No impact on overall survival (Log-Rank, p = 0·583, 95% CI 0·76-1·67). However, the hazard ratio 0·50 for TTP was highly significant (Log-Rank, p = 0·012, 95% CI 0·28-0·87) in patients with dMMR compared with those with mismatch repair proficient tumours (pMMR).

CONCLUSIONS

Patients with dMMR tumours have a lower risk for recurrence compared to those with pMMR tumours, but this finding did not correlate to better overall survival.

Prognostic impact of ATM mutations in patients with metastatic colorectal cancer

Tumors bearing homologous recombination deficiency are extremely sensitive to DNA double strand breaks induced by several chemotherapeutic agents. ATM gene, encoding a protein involved in DNA damage response, is frequently mutated in colorectal cancer (CRC), but its potential role as predictive and prognostic biomarker has not been fully investigated. We carried out a multicenter effort aimed at defining the prognostic impact of ATM mutational status in metastatic CRC (mCRC) patients. Mutational profiles were obtained by means of next-generation sequencing. Overall, 35 out of 227 samples (15%) carried an ATM mutation. At a median follow-up of 56.6 months, patients with ATM mutated tumors showed a significantly longer median overall survival (OS) versus ATM wild-type ones (64.9 vs 34.8 months; HR, 0.50; 95% CI, 0.29-0.85; P = 0.01). In the multivariable model, ATM mutations confirmed the association with longer OS (HR, 0.57; 95% CI, 0.33-0.98; P = 0.04). The prognostic impact of ATM mutations was independent from TP53 mutational status and primary tumor location. High heterogeneity score for ATM mutations, possibly reflecting the loss of wild-type allele, was associated with excellent prognosis. In conclusion, we showed that ATM mutations are independently associated with longer OS in patients with mCRC.

[Expression of secreted frizzled-related protein 4 in DNA mismatch repair-deficient and mismatch repair-proficient colorectal cancers]

OBJECTIVE

To investigate the expressions of secreted frizzled-related protein 4 (SFRP4) in stage Ⅱ DNA mismatch repair-deficient (dMMR) and mismatch repair- proficient (pMMR) colorectal cancers and explore their clinical significance.

METHODS

We collected fresh stage Ⅱ colon cancer tissues with different MMR status detected by immunohistochemistry (IHC). The differentially expressed mRNAs between dMMR and pMMR tumors were identified by Affymetrix Human oeLncRNA gene chip, and the expression of SFRP4 in these cancer tissues and in colorectal cancer cell lines were detected using Western blotting and real- time quantitative PCR. The apoptosis rates of HCT116 cells with and without siRNA- mediated transient SFRP4 knockdown were determined using flow cytometry. We further investigated the expression pattern of Ki-67 and its correlation with SFRP4 expression.

RESULTS

Compared with pMMR colon cancer tissues or cells, both dMMR colon cancer tissues (P=0.014) and cells (P=0.0079) showed significantly increased expression of SFRP4, which was in negative correlation with Ki-67 (P=0.041). In HCT116 cells, transient SFRP4 knockdown resulted in decreased cell apoptosis, including both early apoptosis (P=0.003) and late apoptosis (P=0.024).

CONCLUSIONS

Up-regulation of SFRP4 in dMMR stage Ⅱ colon cancer promotes apoptosis and inhibits proliferation of the cancer cells, and may improve the prognosis of dMMR colon cancer.

Base excision repair capacity as a determinant of prognosis and therapy response in colon cancer patients

The DNA-damaging agent 5-fluorouracil represents the most commonly used chemotherapeutic drug for colorectal cancer patients. DNA lesions associated with 5-fluorouracil therapy are primarily repaired by base excision repair (BER) and mismatch repair (MMR) pathways. Published evidence suggests that the individual DNA repair capacity (DRC) may affect a patient's prognosis and response to chemotherapy. With this in mind, we designed a prospective study of which the main aim was to investigate BER-DRC in relation to 5-fluorouracil response as potential predictive and/or prognostic biomarker. BER-DRC was supplemented by a microsatellite instability (MSI) analysis which represents an indirect marker of MMR activity in the tumor. All parameters were measured in paired samples of tumor tissue and non-malignant adjacent mucosa of 123 incident colon cancer patients. Our results indicate that BER-DRC in non-malignant adjacent mucosa was positively associated with overall survival (P = 0.007) and relapse-free survival (P = 0.04). Additionally, in multivariate analysis, good therapy responders in TNM stage II and III with an elevated BER-DRC in mucosa exhibited better overall survival. Moreover, the overall survival of these patients was even better in the presence of a decreased BER-DRC in tumor tissue. The ratio of BER-DRC in tumor tissue over BER-DRC in mucosa positively correlated with advanced tumor stage (P = 0.003). With respect to MSI, we observed that MSI-high tumors were mostly localized in proximal colon; however, in our cohort, the MSI status affected neither patients' prognosis nor survival. In summary, the results of the present study suggest that the level of BER-DRC is associated with patients' survival. BER-DRC represents a potential prognostic biomarker, applicable for prediction of therapy response and useful for individual approach to patients.