Systematic review and meta-analysis of tumour microsatellite-instability status as a predictor of response to fluorouracil-based adjuvant chemotherapy in colorectal cancer

Analyzing pathogenic variants in mismatch repair genes: personalized prevention strategies for lynch syndrome in Chinese families

Background

This study aimed to analyze the pathogenic variants in one family with colorectal cancer and another with endometrial cancer and provide appropriate personalized prevention strategies for carriers of these genetic mutations.

Methods

One proband with colorectal cancer and another with endometrial cancer and their family members were enrolled in this study. Whole-exome sequencing was used to identify pathogenic gene mutations in both families. We compared the structural difference between the wild-type and mutant MSH2 proteins using SWISS-MODEL and PyMOL visualization software.

Results

We identified one novel mutation (NM_000251.2:c.1486delT:p.L496*) in the MSH2 gene in Family I and a known mutation (NM_001258271.1:c.884 + 4A > G) in the MLH1 gene in Family II. The novel mutation (NM_000251.2:c.1486delT:p.L496*) caused a stop gain mutation, resulting in the absence of amino acids 496-934 in the mutant MSH2 protein. This led to the loss of Domain 5 and alterations in the sequences of Domain 3 and Domain 4 regions, resulting in premature termination of MSH2 protein coding. The known mutation (NM_001258271.1:c.884 + 4A > G) in MLH1 causes the skipping of exon 10, producing a truncated protein and undergoing nonsense-mediated decay based on literature reports. Thus, 5-fluorouracil-based adjuvant chemotherapy is not recommended for patients with lynch syndrome.

Conclusion

The novel stop gain mutant (NM_000251.2:c.1486delT:p.L496*) in MSH2 is deemed pathogenic for LS, and the mutant (NM_001258271.1:c.884 + 4A > G) in MLH1 has been further confirmed to be pathogenic. These findings expand the spectrum of mismatch repair gene variations in the ethnic group Han of China and reaffirm the importance of genetic testing for LS.

New advances in the treatment of intermediate and advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, affecting millions of people worldwide. Due to the complexity and variability of the disease, there are major challenges in the treatment of HCC in its intermediate and advanced stages; despite advances in various treatment modalities, there are still gaps in our understanding of effective therapeutic strategies. Key findings from several studies have shown that the combination of immunotherapy and targeted therapy has a synergistic anti-tumor effect, which can significantly enhance efficacy with a favorable safety profile. In addition, other studies have identified potential biomarkers of therapeutic response, such as tumor protein 53 (TP53) and CTNNB1 (encoding β-conjugated proteins), thus providing personalized treatment options for patients with intermediate and advanced hepatocellular carcinoma. The aim of this article is to review the recent advances in the treatment of intermediate and advanced HCC, especially targeted immune-combination therapy, chimeric antigen receptor T cell therapy (CAR-T cell therapy), and gene therapy for these therapeutic options that fill in the gaps in our knowledge of effective treatment strategies, providing important insights for further research and clinical practice.

Development and evaluation of nomograms and risk stratification systems to predict the overall survival and cancer-specific survival of patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, and patients with HCC have a poor prognosis and low survival rates. Establishing a prognostic nomogram is important for predicting the survival of patients with HCC, as it helps to improve the patient's prognosis. This study aimed to develop and evaluate nomograms and risk stratification to predict overall survival (OS) and cancer-specific survival (CSS) in HCC patients. Data from 10,302 patients with initially diagnosed HCC were extracted from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2017. Patients were randomly divided into the training and validation set. Kaplan-Meier survival, LASSO regression, and Cox regression analysis were conducted to select the predictors of OS. Competing risk analysis, LASSO regression, and Cox regression analysis were conducted to select the predictors of CSS. The validation of the nomograms was performed using the concordance index (C-index), the Akaike information criterion (AIC), the Bayesian information criterion (BIC), Net Reclassification Index (NRI), Discrimination Improvement (IDI), the receiver operating characteristic (ROC) curve, calibration curves, and decision curve analyses (DCAs). The results indicated that factors including age, grade, T stage, N stage, M stage, surgery, surgery to lymph node (LN), Alpha-Fetal Protein (AFP), and tumor size were independent predictors of OS, whereas grade, T stage, surgery, AFP, tumor size, and distant lymph node metastasis were independent predictors of CSS. Based on these factors, predictive models were built and virtualized by nomograms. The C-index for predicting 1-, 3-, and 5-year OS were 0.788, 0.792, and 0.790. The C-index for predicting 1-, 3-, and 5-year CSS were 0.803, 0.808, and 0.806. AIC, BIC, NRI, and IDI suggested that nomograms had an excellent predictive performance with no significant overfitting. The calibration curves showed good consistency of OS and CSS between the actual observation and nomograms prediction, and the DCA showed great clinical usefulness of the nomograms. The risk stratification of OS and CSS was built that could perfectly classify HCC patients into three risk groups. Our study developed nomograms and a corresponding risk stratification system predicting the OS and CSS of HCC patients. These tools can assist in patient counseling and guiding treatment decision making.

Association of a novel frameshift variant and a known deleterious variant in MMR genes with Lynch syndrome in Chinese families

BACKGROUND

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome. This condition is characterized by germline variants in DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2. In this study, we analyzed the molecular defects and clinical manifestations of two families affected with CRC and proposed appropriate individual preventive strategies for all carriers of the variant.

METHODS

We recruited two families diagnosed with CRC and combined their family history and immunohistochemical results to analyze the variants of probands and those of other family members by using whole exome sequencing. Subsequently, gene variants in each family were screened by comparing them with the variants available in the public database. Sanger sequencing was performed to verify the variant sites. An online platform ( https://www.uniprot.org ) was used to analyze the functional domains of mutant proteins.

RESULTS

A novel frameshift variant (NM_001281492, c.1129_1130del, p.R377fs) in MSH6 and a known deleterious variant (NM_000249.4:c.1731G > A, p.S577S) in MLH1 were identified in the two families with CRC. Using bioinformatics tools, we noted that the frameshift variant reduced the number of amino acids in the MSH6 protein from 1230 to 383, thereby leading to no MSH6 protein expression. The silent variant caused splicing defects and was strongly associated with LS. 5-Fluorouracil-based adjuvant chemotherapy is not recommended for patients with LS.

CONCLUSIONS

The novel frameshift variant (MSH6, c.1129_1130del, p.R377fs) is likely pathogenic to LS, and the variant (MLH1, c.1731G > A, p.S577S) has been further confirmed to be pathogenic to LS. Our findings underscore the significance of genetic testing for LS and recommend that genetic consultation and regular follow-ups be conducted to guide individualized treatment for cancer-afflicted families, especially those with a deficiency in MMR expression.

A perspective on emerging therapies in metastatic colorectal cancer: Focusing on molecular medicine and drug resistance

The majority of cancer cases are colorectal cancer, which is also the second largest cause of cancer-related deaths worldwide. Metastasis is the leading cause of death for patients with colorectal cancer. Metastatic colorectal cancer incidence are on the rise due to a tiny percentage of tumors developing resistant to medicines despite advances in treatment tactics. Cutting-edge targeted medications are now the go-to option for customized and all-encompassing CRC care. Specifically, multitarget kinase inhibitors, antivascular endothelial growth factors, and epidermal growth factor receptors are widely used in clinical practice for CRC-targeted treatments. Rare targets in metastatic colorectal cancer are becoming more well-known due to developments in precision diagnostics and the extensive use of second-generation sequencing technology. These targets include the KRAS mutation, the BRAF V600E mutation, the HER2 overexpression/amplification, and the MSI-H/dMMR. Incorporating certain medications into clinical trials has significantly increased patient survival rates, opening new avenues and bringing fresh viewpoints for treating metastatic colorectal cancer. These focused therapies change how cancer is treated, giving patients new hope and better results. These markers can significantly transform and individualize therapy regimens. They could open the door to precisely customized and more effective medicines, improving patient outcomes and quality of life. The fast-growing body of knowledge regarding the molecular biology of colorectal cancer and the latest developments in gene sequencing and molecular diagnostics are directly responsible for this advancement.

The English National Lynch Syndrome transformation project: an NHS Genomic Medicine Service Alliance (GMSA) programme

Objective

In England, through the Genomic Medicine Service Alliances (GMSAs), a national transformation project aims to embed robust pathways to deliver universal Lynch syndrome (LS) testing for patients with colorectal and endometrial cancers. Prior to commencement of the project, there was evidence of variation and low testing levels in eligible patients which is consistent with other health systems; however, we believe this is amenable to systematic improvement with responsibility for testing delivery by local cancer teams supported by regional infrastructure.

Methods and analysis

A project team and national oversight group was formed in May 2021 with membership including 21×cancer alliances, 7×GMSAs, charities and other stakeholders who agreed key performance indicators. 'LS champions' within each cancer team were identified and surveyed. Workforce training focused on effective identification of eligible patients, overcoming barriers and mainstreamed constitutional genetic testing. Comprehensive pathway data analysis was performed in conjunction with the National Disease Registration Service.

Results

Survey and baseline testing data illustrated variation, and a disparity between practice and perception, in levels of testing. The main reported barriers related to funding streams and systematic approaches. Multifaceted training programmes were produced to support workforce development. Champions responsible for testing delivery were appointed in >95% of cancer teams. We identified >9000 historically diagnosed LS patients to support ascertainment for a nationally coordinated screening programme.

Conclusion

This ongoing transformational project is strongly supported by stakeholders in England. Significant quality improvement has been implemented, facilitating systematic delivery of universal testing for LS nationally and reduction in variation in care.

Colorectal medullary carcinoma: heterogeneous presentations of a rare clinico-pathological entity. Report of two cases

Colorectal medullary carcinoma (CMC) is a rare subset of minimally differentiated carcinomas. CMC tend to be right-sided and present at an advanced stage. Despite this, distant metastases are rare at presentation. The liver and the regional lymph nodes represent the most common sites of metastases. Most of the time, CMCs exhibit mismatch repair deficiency and a strong association with high-level microsatellite instability. There is no conspicuous data regarding treatment strategies and short-term outcomes. CMC is supposed to be related to better prognosis compared to poorly-differentiated and undifferentiated colonic adenocarcinomas, but reports are controversial.This lesion, with heterogeneous presentations and unclear prognostic significance, may be unfamiliar to histopathologists and can lead to diagnostic uncertainty and overtreatments.Our aim is to renew the attention to this rare histological subtype through the report of two cases.

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.