Molecular pathology of Lynch syndrome

Mismatch Repair (MMR) Gene Mutation Carriers Have Favorable Outcome in Colorectal and Endometrial Cancer: A Prospective Cohort Study

Germline (Lynch syndrome, LS) and somatic deficiencies of mismatch repair proteins (MMRd) are linked to colorectal and endometrial cancer; however, their prognostic impact in Asian populations remains unclear. This prospective cohort study aimed to determine the prevalence and outcome of germline and somatic MMRd in cancer patients suspected of LS. Patients with colorectal or endometrial cancer suspected of LS were enrolled and underwent gene sequencing for germline MMRd (gMMRd) and immunohistochemistry staining of MMR proteins in a subset of the pathological samples (pMMRd). Among the 451 enrolled patients, 36 patients were gMMRd (+). Compared with gMMRd (-) patients, the 10-year relapse-free survival in gMMRd (+) patients was significantly higher (100% vs. 77.9%; p = 0.006), whereas the 10-year overall survival was similar (100% vs. 90.9%; p = 0.12). Among the 102 gMMRd (-) patients with available pMMR status, 13.7% were pMMRd (+). The 5-year relapse-free survival was 62.9% in gMMRd (-) pMMRd (+) patients and 35.0% in gMMRd (-) pMMRd (-) patients, both lower than gMMRd (+) patients (100%; p < 0.001). This study showed that having LS confers a favorable outcome in colorectal and endometrial cancer patients and highlights the importance of germline genetic testing following the detection of somatic MMRd.

Prevention, diagnosis and clinical management of hereditary breast cancer beyond BRCA1/2 genes

The detection of germline pathogenic variants (gPVs) in BRCA1/2 and other breast cancer (BC) genes is rising exponentially thanks to the advent of multi-gene panel testing. This promising technology, coupled with the availability of specific therapies for BC BRCA-related, has increased the number of patients eligible for genetic testing. Implementing multi-gene panel testing for hereditary BC screening holds promise to maximise benefits for patients at hereditary risk of BC. These benefits range from prevention programs to antineoplastic-targeted therapies. However, the clinical management of these patients is complex and requires guidelines based on recent evidence. Furthermore, applying multi-gene panel testing into clinical practice increases the detection of variants of uncertain significance (VUSs). This augments the complexity of patients' clinical management, becoming an unmet need for medical oncologists. This review aims to collect updated evidence on the most common BC-related genes besides BRCA1/2, from their biological role in BC development to their potential impact in tailoring prevention and treatment strategies.

An Unusual Presentation of Synchronous Breast Cancer and Skin Malignancy in a Patient with Lynch Syndrome: A Case Report and Review of the Literature

BACKGROUND

Lynch syndrome is an autosomal dominant condition that leads to an increased risk of many neoplasms. In the United Kingdom, NICE recommends that patients with colorectal and endometrial cancer should be tested for Lynch syndrome. There is conflicting evidence in the literature on the link between breast cancer and Lynch syndrome.

CASE PRESENTATION

A 54-year-old woman presented with a lump in her right breast with a background of locally advanced colorectal cancer and Lynch syndrome due to a MLH1 gene mutation. A core biopsy showed a grade 3, invasive, triple-negative NST carcinoma. The tumour was triple-negative with patchy positivity for CK14 and CK5/6. Simultaneously, a cystic skin lesion in the contralateral breast was noted, which comprised lesional cells with a proliferation of clear cells and bland basaloid cells. The lesion had evidence of sebaceous differentiation with AR, podoplanin and p63 positivity. MSH1 and PMS2 deficiency was found in the breast and skin lesions.

CONCLUSIONS

In Lynch syndrome, it is vital to be aware of the increased risk of various types of cancer. This case adds to the body of evidence of the spectrum of malignancies that can be encountered in patients with Lynch syndrome.

Insights into MLH1 Methylation in Endometrial Adenocarcinoma through Pyrosequencing Analysis: A Retrospective Observational Study

Background: In cancer care, the MLH1 gene is crucial for DNA mismatch repair (MMR), serving as a vital tumor suppressor. Evaluating MLH1 protein expression status, followed by analysis of MLH1 promoter methylation, has become a key diagnostic and prognostic approach. Our study investigates the complex link between MLH1 methylation and prognosis in endometrial adenocarcinoma (EA) patients. Methodology: MLH1 methylation status was accessed by a Pyrosequencing (PSQ) assay. Qualitative positivity for methylation was established if it exceeded the 11% cut-off; as well, a quantitative methylation analysis was conducted to establish correlations with clinicopathological data, relapse-free survival, and disease-free survival. Results: Our study revealed that 33.3% of patients without MLH1 methylation experienced relapses, surpassing the 23.3% in patients with methylation. Furthermore, 16.7% of patients without methylation succumbed to death, with a slightly higher rate of 17.6% in methylated patients. Qualitative comparisons highlighted that the mean methylation rate in patients experiencing relapse was 35.8%, whereas in those without relapse, it was 42.2%. This pattern persisted in disease-specific survival (DSS), where deceased patients exhibited a higher mean methylation level of 49.1% compared to living patients with 38.8%. Conclusions: Our findings emphasize the efficacy of PSQ for evaluating MLH1 methylation. While unmethylation appears to be associated with a higher relapse rate, the survival rate does not seem to be influenced by methylation. Quantitative percentages suggest that elevated MLH1 methylation is linked to relapse and mortality, though a study with a larger sample size would be essential for statistically significant results.

Current Trends in Vaccine Development for Hereditary Colorectal Cancer Syndromes

The coming of age for cancer treatment has experienced exponential growth in the last decade with the addition of immunotherapy as the fourth pillar to the fundamentals of cancer treatment-chemotherapy, surgery, and radiation-taking oncology to an astounding new frontier. In this time, rapid developments in computational biology coupled with immunology have led to the exploration of priming the host immune system through vaccination to prevent and treat certain subsets of cancer such as melanoma and hereditary colorectal cancer. By targeting the immune system through tumor-specific antigens-namely, neoantigens (neoAgs)-the future of cancer prevention may lie within arm's reach by employing neoAg vaccines as an immune-preventive modality for hereditary cancer syndromes like Lynch syndrome. In this review, we discuss the history, current trends, utilization, and future direction of neoAg-based vaccines in the setting of hereditary colorectal cancer.

Microsatellite instability and mismatch repair protein deficiency: equal predictive markers?

Current clinical guidelines recommend mismatch repair (MMR) protein immunohistochemistry (IHC) or molecular microsatellite instability (MSI) tests as predictive markers of immunotherapies. Most of the pathological guidelines consider MMR protein IHC as the gold standard test to identify cancers with MMR deficiency and recommend molecular MSI tests only in special circumstances or to screen for Lynch syndrome. However, there are data in the literature which suggest that the two test types may not be equal. For example, molecular epidemiology studies reported different rates of deficient MMR (dMMR) and MSI in various cancer types. Additionally, direct comparisons of the two tests revealed relatively frequent discrepancies between MMR IHC and MSI tests, especially in non-colorectal and non-endometrial cancers and in cases with unusual dMMR phenotypes. There are also scattered clinical data showing that the efficacy of immune checkpoint inhibitors is different if the patient selection was based on dMMR versus MSI status of the cancers. All these observations question the current dogma that dMMR phenotype and genetic MSI status are equal predictive markers of the immunotherapies.

Pathological Features of Colorectal Adenocarcinoma Patients Related to MLH1

Background

MLH1, one of the MMR proteins, is linked to DNA replication, its role being to repair the incorrect DNA sequences and to replace them with proper ones. The loss of the MLH1 gene expression is part of Lynch syndrome which can lead to a series of cancers like colorectal and endometrial ones. The aim of this paper is to correlate the levels of MLH1 in four different bio-logical fluids with clinicopathological features in colorectal cancer patients in order to predict them with high probability. Therefore, a mathematical model with given code in Matlab has been proposed to get the clinicopathological features with high probability by only introducing the values for MLH1 concentrations. All these data can be obtained in a very short time even before surgery which can be very helpful the surgeon and the oncologist.

Methods

Four types of samples (whole blood, saliva, urine and tissue) were analyzed using stochastic microsensors; concentrations of MLH1 were determined and compared with different macroscopic and micro-scopic pathological features to obtain mathematical models for early, non-invasive diagnostic of colorectal adenocarcinoma.

Results

There have been established criteria and mathematical models for tumor location, TNM grading system, depth of the tumor, lymphatic, vascular and perineural invasions and the presence of mucus in the tumoral mass.

Conclusions

By using whole blood, saliva and urine samples, the location can be approximated. The proposed mathematical models aimed to allow a minim/noninvasive characterization of the tumor and its location which can help the surgeon and the oncologist to choose faster the personalized treatment.

Low-Grade Mucinous Neoplasm Arising in an Enteric Duplication Cyst of Pancreas: A Case Report and Literature Review

Background. Enteric duplication cysts are rare but can occur in various parts of the gastrointestinal tract, including the pancreas. Most enteric duplication cysts are benign; however, neoplastic transformation has been reported in a few cases, with adenocarcinoma being the most common malignant transformation. Case Presentation. We present an adult with a pancreatic enteric duplication cyst and low-grade mucinous neoplasm. The patient did not exhibit any clinically significant symptoms or physical signs. Imaging revealed a cystic mass in the pancreatic head. Upon pathological examination, the cyst was found to have a bilayered muscular wall with an inner surface lined with pseudostratified mucinous columnar epitheliums. High-power microscopy revealed low-grade dysplasia in epithelial cells. The final pathological diagnosis confirmed an enteric duplication cyst with a low-grade mucinous neoplasm. Conclusion. To the best of our knowledge, this is the first reported case of a low-grade mucinous neoplasm occurring in an enteric duplication cyst in the pancreas. The importance of complete surgical resection and adequate pathological sampling is emphasized to avoid the missed detection of dysplasia or malignancy in these duplication cysts.

Lynch Syndrome: From Multidisciplinary Management to Precision Prevention

BACKGROUND AND AIMS

Lynch syndrome (LS) is currently one of the most prevalent hereditary cancer conditions, accounting for 3% of all colorectal cancers and for up to 15% of those with DNA mismatch repair (MMR) deficiency, and it was one of the first historically identified. The understanding of the molecular carcinogenesis of LS tumors has progressed significantly in recent years. We aim to review the most recent advances in LS research and explore genotype-based approaches in surveillance, personalized cancer prevention, and treatment strategies.

METHODS

PubMed was searched to identify relevant studies, conducted up to December 2023, investigating molecular carcinogenesis in LS, surveillance strategies, cancer prevention, and treatment in LS tumors.

RESULTS

Multigene panel sequencing is becoming the benchmark in the diagnosis of LS, allowing for the detection of a pathogenic constitutional variant in one of the MMR genes. Emerging data from randomized controlled trials suggest possible preventive roles of resistant starch and/or aspirin in LS. Vaccination with immunogenic frameshift peptides appears to be a promising approach for both the treatment and prevention of LS-associated cancers, as evidenced by pre-clinical and preliminary phase 1/2a studies.

CONCLUSIONS

Although robust diagnostic algorithms, including prompt testing of tumor tissue for MMR defects and referral for genetic counselling, currently exist for suspected LS in CRC patients, the indications for LS screening in cancer-free individuals still need to be refined and standardized. Investigation into additional genetic and non-genetic factors that may explain residual rates of interval cancers, even in properly screened populations, would allow for more tailored preventive strategies.

Performance reporting design in artificial intelligence studies using image-based TNM staging and prognostic parameters in rectal cancer: a systematic review

PURPOSE

The integration of artificial intelligence (AI) and magnetic resonance imaging in rectal cancer has the potential to enhance diagnostic accuracy by identifying subtle patterns and aiding tumor delineation and lymph node assessment. According to our systematic review focusing on convolutional neural networks, AI-driven tumor staging and the prediction of treatment response facilitate tailored treat-ment strategies for patients with rectal cancer.

METHODS

This paper summarizes the current landscape of AI in the imaging field of rectal cancer, emphasizing the performance reporting design based on the quality of the dataset, model performance, and external validation.

RESULTS

AI-driven tumor segmentation has demonstrated promising results using various convolutional neural network models. AI-based predictions of staging and treatment response have exhibited potential as auxiliary tools for personalized treatment strategies. Some studies have indicated superior performance than conventional models in predicting microsatellite instability and KRAS status, offer-ing noninvasive and cost-effective alternatives for identifying genetic mutations.

CONCLUSION

Image-based AI studies for rectal can-cer have shown acceptable diagnostic performance but face several challenges, including limited dataset sizes with standardized data, the need for multicenter studies, and the absence of oncologic relevance and external validation for clinical implantation. Overcoming these pitfalls and hurdles is essential for the feasible integration of AI models in clinical settings for rectal cancer, warranting further research.

Molecular pathological classification of colorectal cancer-an update

Colorectal cancer (CRC) has a broad range of molecular alterations with two major mechanisms of genomic instability (chromosomal instability and microsatellite instability) and has been subclassified into 4 consensus molecular subtypes (CMS) based on bulk RNA sequence data. Here, we update the molecular pathological classification of CRC with an overview of more recent bulk and single-cell RNA data analysis for development of transcriptional classifiers and risk stratification methods, taking into account the marked inter-tumoural and intra-tumoural heterogeneity of CRC. The importance of the stromal and immune components or tumour microenvironment (TME) to prognosis has emerged from these analyses. Attempts to remove the contribution of the tumour microenvironment and reveal neoplastic-specific transcriptional traits involved identification of the CRC intrinsic subtypes (CRIS). The use of immunohistochemistry and digital pathology to implement classification systems are evolving fields. Conventional adenoma versus serrated polyp pathway transcriptomic analysis and characterisation of canonical LGR5+ crypt base columnar stem cell versus ANXA1+ regenerative stem cell phenotypes emerged as key properties for improved understanding of transcriptional signals involved in molecular subclassification of colorectal cancers. Recently, classification by three pathway-derived subtypes (PDS1-3) has been developed, revealing a continuum of intrinsic biology associated with biological, stem cell, histopathological, and clinical attributes.

Prognostic value and immunological role of PD-L1 gene in pan-cancer

OBJECTIVE

PD-L1, a target of immune checkpoint blockade, has been proven to take the role of an oncogene in most human tumors. However, the role of PD-L1 in human pan-cancers has not yet been fully investigated.

MATERIALS AND METHODS

Pan-cancer analysis was conducted to analyze expression, genetic alterations, prognosis analysis, and immunological characteristics of PD-L1. Estimating the correlation between PD-L1 expression and survival involved using pooled odds ratios and hazard ratios with 95% CI. The Kaplan-Meier (K-M) technique, COX analysis, and receiver operating characteristic (ROC) curves were applied to the survival analysis. Additionally, we investigated the relationships between PD-L1 and microsatellite instability (MSI), tumor mutational burden (TMB), DNA methyltransferases (DNMTs), the associated genes of mismatch repair (MMR), and immune checkpoint biomarkers using Spearman's correlation analysis. Also, immunohistochemical analysis and qRT-PCR were employed in evaluating PD-L1's protein and mRNA expression in pan-caner.

RESULTS

PD-L1 showed abnormal mRNA and protein expression in a variety of cancers and predicted prognosis in cancer patients. Furthermore, across a variety of cancer types, the aberrant PD-L1 expression was connected to the MSI, MMR, TMB, drug sensitivity, and tumor immune microenvironment (TIME). Moreover, PD-L1 was significantly correlated with infiltrating levels of immune cells (T cell CD8 + , neutrophil, and so on).

CONCLUSION

Our study provides a better theoretical basis and guidance for the clinical treatment of PD-L1.

Current status and perspectives of genetic testing in gastrointestinal cancer (Review)

Genetic testing has become widespread in daily medical care for gastrointestinal (GI) cancers. However, unlike breast cancer and non-small cell lung cancer, in which personalized medicine targeting various driver genes is standardized, the incidence of targeted gene abnormalities in GI cancers is low. Nevertheless, such abnormalities may be linked to therapeutic agents and the further development of therapeutic agents for personalized medicine for GI cancers is desired. A liquid biopsy is of great benefit in offering clinical decision support, in applications such as GI cancer screening, surgical interventions, monitoring disease status and enhancing patient survival outcomes, all of which would contribute to personalized medicine. Germline genetic testing is required for several types of GI cancer, which shows clinical indications of hereditary predisposition. The increasing use of multigene panel testing has redefined gene-cancer associations, and consequently the estimate of cancer risk that vary from low to high penetrance. Comprehensive genetic testing can enable the detection of novel treatment targets and the discovery of undefined multiple diagnostic/predictive markers, which may enhance the molecular-level understanding of GI cancers. Genetic testing can also aid the design of more appropriate and adequate genomic-driven therapies for patients who may benefit from other standardized therapeutic methods.

Genetic modifiers of repeat expansion disorders

Repeat expansion disorders (REDs) are monogenic diseases caused by a sequence of repetitive DNA expanding above a pathogenic threshold. A common feature of the REDs is a strong genotype-phenotype correlation in which a major determinant of age at onset (AAO) and disease progression is the length of the inherited repeat tract. Over a disease-gene carrier's life, the length of the repeat can expand in somatic cells, through the process of somatic expansion which is hypothesised to drive disease progression. Despite being monogenic, individual REDs are phenotypically variable, and exploring what genetic modifying factors drive this phenotypic variability has illuminated key pathogenic mechanisms that are common to this group of diseases. Disease phenotypes are affected by the cognate gene in which the expansion is found, the location of the repeat sequence in coding or non-coding regions and by the presence of repeat sequence interruptions. Human genetic data, mouse models and in vitro models have implicated the disease-modifying effect of DNA repair pathways via the mechanisms of somatic mutation of the repeat tract. As such, developing an understanding of these pathways in the context of expanded repeats could lead to future disease-modifying therapies for REDs.

Germline Variants in Cancer Predisposition Genes in Pediatric Patients with Central Nervous System Tumors

Central nervous system (CNS) tumors comprise around 20% of childhood malignancies. Germline variants in cancer predisposition genes (CPGs) are found in approximately 10% of pediatric patients with CNS tumors. This study aimed to characterize variants in CPGs in pediatric patients with CNS tumors and correlate these findings with clinically relevant data. Genomic DNA was isolated from the peripheral blood of 51 pediatric patients and further analyzed by the next-generation sequencing approach. Bioinformatic analysis was done using an "in-house" gene list panel, which included 144 genes related to pediatric brain tumors, and the gene list panel Neoplasm (HP:0002664). Our study found that 27% of pediatric patients with CNS tumors have a germline variant in some of the known CPGs, like ALK, APC, CHEK2, ELP1, MLH1, MSH2, NF1, NF2 and TP53. This study represents the first comprehensive evaluation of germline variants in pediatric patients with CNS tumors in the Western Balkans region. Our results indicate the necessity of genomic research to reveal the genetic basis of pediatric CNS tumors, as well as to define targets for the application and development of innovative therapeutics that form the basis of the upcoming era of personalized medicine.

Detection of Germline Mutations in a Cohort of 250 Relatives of Mutation Carriers in Multigene Panel: Impact of Pathogenic Variants in Other Genes beyond BRCA1/2

BACKGROUND

Several hereditary-familial syndromes associated with various types of tumors have been identified to date, evidencing that hereditary cancers caused by germline mutations account for 5-10% of all tumors. Advances in genetic technology and the implementation of Next-Generation Sequencing (NGS) have accelerated the discovery of several susceptibility cancer genes, allowing for the detection of cancer-predisposing mutations in a larger number of cases. The aim of this study is to highlight how the application of an NGS-multigene panel to a group of oncological patients subsequently leads to improvement in the identification of carriers of healthy pathogenic variants/likely pathogenic variants (PVs/LPVs) and prevention of the disease in these cases.

METHODS

Starting from a total of 110 cancer patients carrying PVs/LPVs in genes involved in cancer susceptibility detected via a customized NGS panel of 27 cancer-associated genes, we enrolled 250 healthy collateral family members from January 2020 to July 2022. The specific PVs/LPVs identified in each proband were tested in healthy collateral family members via Sanger sequencing.

RESULTS

A total of 131 out of the 250 cases (52%) were not carriers of the mutation detected in the affected relative, while 119 were carriers. Of these, 81/250 patients carried PVs/LPVs on BRCA1/2 (33%), 35/250 harbored PVs/LPVs on other genes beyond BRCA1 and BRCA2 (14%), and 3/250 (1%) were PVs/LPVs carriers both on BRCA1/2 and on another susceptibility gene.

CONCLUSION

Our results show that the analysis of BRCA1/2 genes would have only resulted in a missed diagnosis in a number of cases and in the lack of prevention of the disease in a considerable percentage of healthy carriers with a genetic mutation (14%).

A Highly Sensitive Pan-Cancer Test for Microsatellite Instability

Microsatellite instability (MSI) is an evolving biomarker for cancer detection and treatment. MSI was first used to identify patients with Lynch syndrome, a hereditary form of colorectal cancer (CRC), but has recently become indispensable in predicting patient response to immunotherapy. To address the need for pan-cancer MSI detection, a new multiplex assay was developed that uses novel long mononucleotide repeat (LMR) markers to improve sensitivity. A total of 469 tumor samples from 20 different cancer types, including 319 from patients with Lynch syndrome, were tested for MSI using the new LMR MSI Analysis System. Results were validated by using deficient mismatch repair (dMMR) status according to immunohistochemistry as the reference standard and compared versus the Promega pentaplex MSI panel. The sensitivity of the LMR panel for detection of dMMR status by immunohistochemistry was 99% for CRC and 96% for non-CRC. The overall percent agreement between the LMR and Promega pentaplex panels was 99% for CRC and 89% for non-CRC tumors. An increased number of unstable markers and the larger size shifts observed in dMMR tumors using the LMR panel increased confidence in MSI determinations. The LMR MSI Analysis System expands the spectrum of cancer types in which MSI can be accurately detected.

Preventive strategies in familial and hereditary colorectal cancer

Colorectal cancer is a leading cause of cancer-related deaths worldwide. While most cases are sporadic, a significant proportion of cases are associated with familial and hereditary syndromes. Individuals with a family history of colorectal cancer have an increased risk of developing the disease, and those with hereditary syndromes such as Lynch syndrome or familial adenomatous polyposis have a significantly higher risk. In these populations, preventive strategies are critical for reducing the incidence and mortality of colorectal cancer. This review provides an overview of current preventive strategies for individuals at increased risk of colorectal cancer due to familial or hereditary factors. The manuscript includes a discussion of risk assessment and genetic testing, highlighting the importance of identifying at-risk individuals and families. This review describes various preventive measures, including surveillance colonoscopy, chemoprevention, and prophylactic surgery, and their respective benefits and limitations. Together, this work highlights the importance of preventive strategies in familial and hereditary colorectal cancer.

Prognostic Biomarkers of Cell Proliferation in Colorectal Cancer (CRC): From Immunohistochemistry to Molecular Biology Techniques

Colorectal cancer (CRC) is one of the most common and severe malignancies worldwide. Recent advances in diagnostic methods allow for more accurate identification and detection of several molecular biomarkers associated with this cancer. Nonetheless, non-invasive and effective prognostic and predictive testing in CRC patients remains challenging. Classical prognostic genetic markers comprise mutations in several genes (e.g., APC, KRAS/BRAF, TGF-β, and TP53). Furthermore, CIN and MSI serve as chromosomal markers, while epigenetic markers include CIMP and many other candidates such as SERP, p14, p16, LINE-1, and RASSF1A. The number of proliferation-related long non-coding RNAs (e.g., SNHG1, SNHG6, MALAT-1, CRNDE) and microRNAs (e.g., miR-20a, miR-21, miR-143, miR-145, miR-181a/b) that could serve as potential CRC markers has also steadily increased in recent years. Among the immunohistochemical (IHC) proliferative markers, the prognostic value regarding the patients' overall survival (OS) or disease-free survival (DFS) has been confirmed for thymidylate synthase (TS), cyclin B1, cyclin D1, proliferating cell nuclear antigen (PCNA), and Ki-67. In most cases, the overexpression of these markers in tissues was related to worse OS and DFS. However, slowly proliferating cells should also be considered in CRC therapy (especially radiotherapy) as they could represent a reservoir from which cells are recruited to replenish the rapidly proliferating population in response to cell-damaging factors. Considering the above, the aim of this article is to review the most common proliferative markers assessed using various methods including IHC and selected molecular biology techniques (e.g., qRT-PCR, in situ hybridization, RNA/DNA sequencing, next-generation sequencing) as prognostic and predictive markers in CRC.

Mismatch Repair Screening of Gastrointestinal Cancers: The Impact on Lynch Syndrome Detection and Immunotherapy

INTRODUCTION

Mismatch repair immunohistochemistry (MMR IHC) or microsatellite instability (MSI) testing is now routinely performed in patients with colorectal cancer (CRC) to select those requiring Lynch syndrome testing. MMR IHC is also carried out on CRC and upper gastrointestinal (GI) cancers to select patients for immunotherapy. We review the Royal Marsden Hospital's pathway of molecular to germline testing for Lynch syndrome in the context of NICE guidance and the National Test Directory.

METHODS

We conducted (i) a retrospective audit of adherence to NICE guidance DG27 for patients diagnosed with CRC March 2017-August 2018 and (ii) a retrospective service evaluation of MMR IHC/Lynch syndrome testing in patients diagnosed with upper GI cancers January 2019-2020.

RESULTS

Of 394 patients with CRC, 346 (87.8%) had MMR IHC testing. Thirty-eight of 346 (10.9%) were MMR deficient (MMR-D) and 5 (1.4%) were found to have pathogenic germline variants causing Lynch syndrome. Of 405 patients with upper GI cancers, 221 (54.6%) had MMR IHC testing. Ten of 221 (4.5%) were MMR-D and 1 (0.5%) had a pathogenic germline variant causing Lynch syndrome.

DISCUSSION

This study highlights the small but significant number of patients, with CRC or upper GI cancers, which were caused by Lynch syndrome. It also highlights weaknesses in our testing pathway that limit access to germline testing. As MMR testing increases, it is important that clinicians are aware that patients with MMR-D tumours require reflex somatic testing or referral for germline testing. We have incorporated the guidelines into a pathway for use in clinics and multidisciplinary teams.

Mismatch Repair Protein Expression in Endometrial Cancer: Assessing Concordance and Unveiling Pitfalls in Two Different Immunohistochemistry Assays

This study aimed to compare the concordance and interchangeability of the Dako/Agilent and Ventana/Roche mismatch repair (MMR) immunohistochemistry (IHC) assays commonly used in pathology. It also aimed to provide diagnostic insights by examining the frequency and characteristics of the dot-like artifact observed in MLH1 M1 clone staining in endometrial cancer. Fifty endometrial cancer cases with MMR deficiency, excised between 2011 and 2018, were included in the study. IHC was performed using primary antibody clones from Ventana/Roche (MLH1, clone M1; MSH2, G219-1129; MSH6, SP93; PMS2, A16-4) and Dako/Agilent (MLH1, ES05; MSH2, FE11; MSH6, EP49; PMS2, EP51). Both assays were conducted using respective autostainers. The Dako/Agilent assay showed a loss of MLH1 in 26 cases, MSH2 in 12 cases, MSH6 in 23 cases, and PMS2 in 28 cases. The two assays had a complete agreement in MMR protein expression or loss. The dot-like artifact in MLH1 M1 clone staining was observed in 77% (20/26) of cases, predominantly in the surface area of the tumor, ranging from 5% to 40% (median: 10%). These findings highlight the high concordance between the MMR-IHC assays and emphasize the importance of considering the dot-like artifact in MLH1 M1 clone staining when diagnosing endometrial cancer with MMR deficiency.

Lynch Syndrome Biopathology and Treatment: The Potential Role of microRNAs in Clinical Practice

Lynch syndrome (LS), also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is an autosomal dominant cancer syndrome which causes about 2-3% of cases of colorectal carcinoma. The development of LS is due to the genetic and epigenetic inactivation of genes involved in the DNA mismatch repair (MMR) system, causing an epiphenomenon known as microsatellite instability (MSI). Despite the fact that the genetics of the vast majority of MSI-positive (MSI+) cancers can be explained, the etiology of this specific subset is still poorly understood. As a possible new mechanism, it has been recently demonstrated that the overexpression of certain microRNAs (miRNAs, miRs), such as miR-155, miR-21, miR-137, can induce MSI or modulate the expression of the genes involved in LS pathogenesis. MiRNAs are small RNA molecules that regulate gene expression at the post-transcriptional level by playing a critical role in the modulation of key oncogenic pathways. Increasing evidence of the link between MSI and miRNAs in LS prompted a deeper investigation into the miRNome involved in these diseases. In this regard, in this study, we discuss the emerging role of miRNAs as crucial players in the onset and progression of LS as well as their potential use as disease biomarkers and therapeutic targets in the current view of precision medicine.

Acetaldehyde and defective mismatch repair increase colonic tumours in a Lynch syndrome model with Aldh1b1 inactivation

ALDH1B1 expressed in the intestinal epithelium metabolises acetaldehyde to acetate, protecting against acetaldehyde-induced DNA damage. MSH2 is a key component of the DNA mismatch repair (MMR) pathway involved in Lynch syndrome (LS)-associated colorectal cancers. Here, we show that defective MMR (dMMR) interacts with acetaldehyde, in a gene/environment interaction, enhancing dMMR-driven colonic tumour formation in a LS murine model of Msh2 conditional inactivation (Lgr5-CreER; Msh2flox/-, or Msh2-LS) combined with Aldh1b1 inactivation. Conditional (Aldh1b1flox/flox) or constitutive (Aldh1b1-/-) Aldh1b1 knockout alleles combined with the conditional Msh2flox/- intestinal knockout mouse model of LS (Msh2-LS) received either ethanol, which is metabolised to acetaldehyde, or water. We demonstrated that 41.7% of ethanol-treated Aldh1b1flox/flox Msh2-LS mice and 66.7% of Aldh1b1-/- Msh2-LS mice developed colonic epithelial hyperproliferation and adenoma formation, in 4.5 and 6 months, respectively, significantly greater than 0% in water-treated control mice. Significantly higher numbers of dMMR colonic crypt foci precursors and increased plasma acetaldehyde levels were observed in ethanol-treated Aldh1b1flox/flox Msh2-LS and Aldh1b1-/- Msh2-LS mice compared with those in water-treated controls. Hence, ALDH1B1 loss increases acetaldehyde levels and DNA damage that interacts with dMMR to accelerate colonic, but not small intestinal, tumour formation.

The MSH2 c.793-1G>A variant disrupts normal splicing and is associated with Lynch syndrome

Instruction

Lynch syndrome (LS) is the most common inherited cancer predisposition disorder of colorectal cancer (CRC) which is associated with pathogenic variants in 4 mismatch repair (MMR) genes. Here, we reported a multi-generation Chinese family clinically diagnosed with LS.

Methods

To identify the underlying pathogenic gene variants, 30 whole blood samples and 4 colorectal cancer tissue samples and their clinical data were obtained from this four-generation family. Microsatellite instability-high (MSI) testing, immunohistochemistry (IHC), and Whole-Exome Sequencing (WES) were performed to identify the MMR/MSI and the underlying gene variants. The minigene splicing assay and in vitro splicing assay were used to explore the function of this variant.

Results

MSI-H and dMMR was revealed by the MSI testing and IHC, Whole-Exome Sequencing (WES) in 3 patients successfully identified a splicing variant (c.793-1G>A) in intron 4 of MSH2. Sanger sequencing validated the WES results, and all the "healthy" individuals carrying the variant have been identified in the family by PCR. Bioinformatics analysis and in vitro minigene assay showed that the pathogenic variant affected the splicing process of MSH2 gene to generate 2 kinds defective transcription products, and consequently reduced the expression of MSH2 protein. The mutation carriers were later recommended for colonoscopy and other important cancer diagnostic inspections every 1-2 years because they both have a higher risk of LS.

Discussion

We found a pathogenic splicing variant (rs863225397, c.793-1G>A) of MSH2 gene, and furtherly confirmed that this mutation plays an important role in LS patients of this pedigree based on the vitro study. Our study indicates that one splicing mutation in the MSH2 gene (c.793-1G>A) causes LS and highlights the importance of LS gene testing.

The Prevalence and Molecular Landscape of Lynch Syndrome in the Affected and General Population

BACKGROUND

Lynch syndrome (LS) is the most frequent genetically pre-disposed colorectal cancer (CRC) syndrome, accounting for 2-3% of all CRC cases. In Estonia, ~1000 new cases are diagnosed each year. This retroactive and prospective study aimed to estimate the prevalence of LS and describe disease-causing variants in mismatch repair (MMR) genes in a diagnostic setting and in the Estonian general population.

METHODS

LS data for the diagnostic cohort were gathered from 2012 to 2022 and data for the general population were acquired from the Estonian Biobank (EstBB). Furthermore, we conducted a pilot study to estimate the improvement of LS diagnostic yield by raising the age limit to >50 years for immunohistochemistry analysis of MMR genes.

RESULTS

We estimated LS live birth prevalence between 1930 and 2003 in Estonia at 1:8638 (95% CI: 1: 9859-7588). During the study period, we gathered 181 LS individuals. We saw almost a six-fold increase in case prevalence, probably deriving from better health awareness, improved diagnostic possibilities and the implementation of MMR IHC testing in a broader age group.

CONCLUSION

The most common genes affected in the diagnostic and EstBB cohorts were MLH1 and PMS2 genes, respectively. The LS diagnosis mean age was 44.8 years for index cases and 36.8 years (p = 0.003) for family members. In the MMR IHC pilot study, 29% had LS.

Construction of the novel immune risk scoring system related to CD8+ T cells in uterine corpus endometrial carcinoma

BACKGROUND

Uterine corpus endometrial carcinoma (UCEC) is a gynecological malignant tumor with high incidence and poor prognosis. Although immunotherapy has brought significant survival benefits to advanced UCEC patients, traditional evaluation indicators cannot accurately identify all potential beneficiaries of immunotherapy. Consequently, it is necessary to construct a new scoring system to predict patient prognosis and responsiveness of immunotherapy.

METHODS

CIBERSORT combined with weighted gene co-expression network analysis (WGCNA), non-negative matrix factorization (NMF), and random forest algorithms to screen the module associated with CD8⁺ T cells, and key genes related to prognosis were selected out by univariate, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses to develop the novel immune risk score (NIRS). Kaplan-Meier (K-M) analysis was used to compare the difference of survival between high- and low- NIRS groups. We  also explored the correlations between NIRS, immune infiltration and immunotherapy, and three external validation sets were used to verify the predictive performance of NIRS. Furthermore, clinical subgroup analysis, mutation analysis, differential expression of immune checkpoints, and drug sensitivity analysis were performed to generate individualized treatments for patients with different risk scores. Finally, gene set variation analysis (GSVA) was conducted to explore the biological functions of NIRS, and qRT-PCR was applied to verify the differential expressions of three trait genes at cellular and tissue levels.

RESULTS

Among the modules clustered by WGCNA, the magenta module was most positively associated with CD8⁺ T cells. Three genes (CTSW, CD3D and CD48) were selected to construct NIRS after multiple screening procedures. NIRS was confirmed as an independent prognostic factor of UCEC, and patients with high NIRS had significantly worse prognosis compared to those with low NIRS. The high NIRS group showed lower levels of infiltrated immune cells, gene mutations, and expression of multiple immune checkpoints, indicating reduced sensitivity to immunotherapy. Three module genes were identified as protective factors positively correlated with the level of CD8⁺ T cells.

CONCLUSIONS

In this study, we constructed NIRS as a novel predictive signature of UCEC. NIRS not only differentiates patients with distinct prognoses and immune responsiveness, but also guides their therapeutic regimens.

QuPath Algorithm Accurately Identifies MLH1-Deficient Inflammatory Bowel Disease-Associated Colorectal Cancers in a Tissue Microarray

Current methods for analysing immunohistochemistry are labour-intensive and often confounded by inter-observer variability. Analysis is time consuming when identifying small clinically important cohorts within larger samples. This study trained QuPath, an open-source image analysis program, to accurately identify MLH1-deficient inflammatory bowel disease-associated colorectal cancers (IBD-CRC) from a tissue microarray containing normal colon and IBD-CRC. The tissue microarray (n = 162 cores) was immunostained for MLH1, digitalised, and imported into QuPath. A small sample (n = 14) was used to train QuPath to detect positive versus no MLH1 and tissue histology (normal epithelium, tumour, immune infiltrates, stroma). This algorithm was applied to the tissue microarray and correctly identified tissue histology and MLH1 expression in the majority of valid cases (73/99, 73.74%), incorrectly identified MLH1 status in one case (1.01%), and flagged 25/99 (25.25%) cases for manual review. Qualitative review found five reasons for flagged cores: small quantity of tissue, diverse/atypical morphology, excessive inflammatory/immune infiltrations, normal mucosa, or weak/patchy immunostaining. Of classified cores (n = 74), QuPath was 100% (95% CI 80.49, 100) sensitive and 98.25% (95% CI 90.61, 99.96) specific for identifying MLH1-deficient IBD-CRC; κ = 0.963 (95% CI 0.890, 1.036) (p < 0.001). This process could be efficiently automated in diagnostic laboratories to examine all colonic tissue and tumours for MLH1 expression.

Characterization of sebaceous and non-sebaceous cutaneous manifestations in patients with lynch syndrome: a systematic review

A subset of patients with Lynch Syndrome demonstrates cutaneous manifestations of the disorder. Characterization of these Lynch-related skin lesions could help in early recognition of patients with Lynch Syndrome. A broad search of the literature on OVID Medline and Embase was carried out to capture papers reporting cutaneous manifestations in Lynch Syndrome patients. The results were uploaded into Mendeley reference management software. The PRISMA workflow was used in the literature selection process. In this systematic review, data were collected from 961 cases from 413 studies, including 380 molecularly confirmed Lynch Syndrome cases. The main skin lesions were: Sebaceous adenomas (43%), sebaceous carcinomas (27%), keratoacanthomas (16%), sebaceomas (13%), squamous cell carcinomas (23%), and basal cell carcinomas (10%). MSH2 variants were the most common underlying genotype (72%). Assessment of mismatch repair by immunohistochemistry, microsatellite instability analysis, or both were performed on 328 skin lesions from 220 (58%) molecularly confirmed cases. In those skin lesions, 95% of Immunohistochemistry and 90% of the microsatellite instability test results were concordant with the underlying genotype. Sebaceous skin lesions are well-recognised phenotypic features of Lynch Syndrome. Our results show that squamous and basal cell carcinomas are relatively common in patients with Lynch syndrome; however, available evidence cannot confirm that Lynch syndrome is causal. Immunohistochemistry and/or microsatellite instability testing of skin tumours in patients with a family history of Lynch Syndrome-associated cancers may be a useful approach in identifying patients requiring referral to Clinical Genetics and/or consideration of germline genetic testing for Lynch Syndrome.

CT-based deep learning model for the prediction of DNA mismatch repair deficient colorectal cancer: a diagnostic study

BACKGROUND

Stratification of DNA mismatch repair (MMR) status in patients with colorectal cancer (CRC) enables individual clinical treatment decision making. The present study aimed to develop and validate a deep learning (DL) model based on the pre-treatment CT images for predicting MMR status in CRC.

METHODS

1812 eligible participants (training cohort: n = 1124; internal validation cohort: n = 482; external validation cohort: n = 206) with CRC were enrolled from two institutions. All pretherapeutic CT images from three dimensions were trained by the ResNet101, then integrated by Gaussian process regression (GPR) to develop a full-automatic DL model for MMR status prediction. The predictive performance of the DL model was evaluated using the area under the receiver operating characteristic curve (AUC) and then tested in the internal and external validation cohorts. Additionally, the participants from institution 1 were sub-grouped by various clinical factors for subgroup analysis, then the predictive performance of the DL model for identifying MMR status between participants in different groups were compared.

RESULTS

The full-automatic DL model was established in the training cohort to stratify the MMR status, which presented promising discriminative ability with the AUCs of 0.986 (95% CI 0.971-1.000) in the internal validation cohort and 0.915 (95% CI 0.870-0.960) in the external validation cohort. In addition, the subgroup analysis based on the thickness of CT images, clinical T and N stages, gender, the longest diameter, and the location of tumors revealed that the DL model showed similar satisfying prediction performance.

CONCLUSIONS

The DL model may potentially serve as a noninvasive tool to facilitate the pre-treatment individualized prediction of MMR status in patients with CRC, which could promote the personalized clinical-making decision.

Insights on the Association between Thyroid Diseases and Colorectal Cancer

Benign and malignant thyroid diseases (TDs) have been associated with the occurrence of extrathyroidal malignancies (EMs), including colorectal cancers (CRCs). Such associations have generated a major interest, as their characterization may provide useful clues regarding diseases’ etiology and/or progression, with the possible identification of shared congenital and environmental elements. On the other hand, elucidation of the underlying molecular mechanism(s) could lead to an improved and tailored clinical management of these patients and stimulate an increased surveillance of TD patients at higher threat of developing EMs. Here, we will examine the epidemiological, clinical, and molecular findings connecting TD and CRC, with the aim to identify possible molecular mechanism(s) responsible for such diseases’ relationship.

Deep Learning Applied to Raman Spectroscopy for the Detection of Microsatellite Instability/MMR Deficient Colorectal Cancer

Defective DNA mismatch repair is one pathogenic pathway to colorectal cancer. It is characterised by microsatellite instability which provides a molecular biomarker for its detection. Clinical guidelines for universal testing of this biomarker are not met due to resource limitations; thus, there is interest in developing novel methods for its detection. Raman spectroscopy (RS) is an analytical tool able to interrogate the molecular vibrations of a sample to provide a unique biochemical fingerprint. The resulting datasets are complex and high-dimensional, making them an ideal candidate for deep learning, though this may be limited by small sample sizes. This study investigates the potential of using RS to distinguish between normal, microsatellite stable (MSS) and microsatellite unstable (MSI-H) adenocarcinoma in human colorectal samples and whether deep learning provides any benefit to this end over traditional machine learning models. A 1D convolutional neural network (CNN) was developed to discriminate between healthy, MSI-H and MSS in human tissue and compared to a principal component analysis–linear discriminant analysis (PCA–LDA) and a support vector machine (SVM) model. A nested cross-validation strategy was used to train 30 samples, 10 from each group, with a total of 1490 Raman spectra. The CNN achieved a sensitivity and specificity of 83% and 45% compared to PCA–LDA, which achieved a sensitivity and specificity of 82% and 51%, respectively. These are competitive with existing guidelines, despite the low sample size, speaking to the molecular discriminative power of RS combined with deep learning. A number of biochemical antecedents responsible for this discrimination are also explored, with Raman peaks associated with nucleic acids and collagen being implicated.

Coronary artery disease-associated immune gene RBP1 and its pan-cancer analysis

Purpose

To identify immune-related biomarkers in coronary artery disease (CAD), investigate their possible function in the immunological milieu of tumors, and initially investigate the mechanisms and therapeutic targets shared by CAD and cancer.

Methods

Download the CAD-related dataset GSE60681 from the GEO database. GSVA and WGCNA analyses were performed based on the GSE60681 dataset to identify the modules most pertinent to CAD, identify candidate hub genes and finally intersect the genes associated with immunity downloaded from the import database to find the hub genes. The GTEx, CCLE, and TCGA database were used to examine the expression of the hub gene in normal tissues, tumor cell lines, tumor tissues, and different tumor STAGES. One-factor cox and Kaplan-Meier analyses were performed to explore the prognosis of hub genes. Hub gene methylation levels in CAD and cancer were analyzed in the diseaseMeth 3.0 and ualcan databases, respectively. R package CiberSort processed the GSE60681 dataset to assess immune infiltration in CAD. TIMER2.0 evaluated hub genes with pan-cancer immune infiltration. The hub genes were analyzed for drug sensitivity and correlation with TMB, MSI, MMR, cancer-related functional status, and immune checkpoints in different tumors. Finally, GSEA was carried out on the crucial genes.

Results

WGCNA were used to pinpoint the green modules that were most closely related to CAD and intersections with immune-related genes were taken to remember the pivotal gene RBP1. RBP1 is hypermethylated in CAD and multiple cancers. Its expression levels in different cancers were associated with poor prognosis of cancer, with significant expression levels at higher stages of cancer staging. The immune infiltration results showed that RBP1 was closely associated with CAD and tumor-associated immune infiltration. The results indicated that RBP1 was strongly correlated with TMB, MSI, MMR, cancer-associated functional status, and immune checkpoints in various cancers. RBP1 was related to the sensitivity of six anticancer drugs. GSEA showed RBP1 was associated with immune cell activation, immune response, and cancer development.

Conclusion

RBP1 is a pivotal gene associated with immunity in CAD and pan-cancer and may mediate the development of CAD and cancer through immunity, making it a common therapeutic target for both.

Tumor-independent Detection of Inherited Mismatch Repair Deficiency for the Diagnosis of Lynch Syndrome with High Specificity and Sensitivity

Lynch syndrome (LS) is the most common hereditary cancer syndrome. Early diagnosis improves prognosis and reduces health care costs, through existing cancer surveillance methods. The problem is finding and diagnosing the cancer predisposing genetic condition. The current workup involves a complex array of tests that combines family cancer history and clinical phenotypes with tumor characteristics and sequencing data, followed by a challenging task to interpret the found variant(s). On the basis of the knowledge that an inherited mismatch repair (MMR) deficiency is a hallmark of LS, we have developed and validated a functional MMR test, DiagMMR, that detects inherited MMR deficiency directly from healthy tissue without need of tumor and variant information. The validation included 119 skin biopsies collected from clinically pathogenic MMR variant carriers (MSH2, MSH6) and controls, and was followed by a small clinical pilot study. The repair reaction was performed on proteins extracted from primary fibroblasts and the interpretation was based on the MMR capability of the sample in relation to cutoff, which distinguishes MMR proficient (non-LS) from MMR deficient (LS) function. The results were compared with the reference standard (germline NGS). The test was shown to have exceptional specificity (100%) with high sensitivity (89%) and accuracy (97%). The ability to efficiently distinguish LS carriers from controls was further shown with a high area under the receiving operating characteristic (AUROC) value (0.97). This test offers an excellent tool for detecting inherited MMR deficiency linked to MSH2 or MSH6 and can be used alone or with conventional tests to recognize genetically predisposed individuals.

SIGNIFICANCE

Clinical validation of DiagMMR shows high accuracy in distinguishing individuals with hereditary MSH2 or MSH6 MMR deficiency (i.e., LS). The method presented overcomes challenges faced by the complexity of current methods and can be used alone or with conventional tests to improve the ability to recognize genetically predisposed individuals.

Immunogenomic Biomarkers and Validation in Lynch Syndrome

Lynch syndrome (LS) is an inherited disorder in which affected individuals have a significantly higher-than-average risk of developing colorectal and non-colorectal cancers, often before the age of 50 years. In LS, mutations in DNA repair genes lead to a dysfunctional post-replication repair system. As a result, the unrepaired errors in coding regions of the genome produce novel proteins, called neoantigens. Neoantigens are recognised by the immune system as foreign and trigger an immune response. Due to the invasive nature of cancer screening tests, universal cancer screening guidelines unique for LS (primarily colonoscopy) are poorly adhered to by LS variant heterozygotes (LSVH). Currently, it is unclear whether immunogenomic components produced as a result of neoantigen formation can be used as novel biomarkers in LS. We hypothesise that: (i) LSVH produce measurable and dynamic immunogenomic components in blood, and (ii) these quantifiable immunogenomic components correlate with cancer onset and stage. Here, we discuss the feasibility to: (a) identify personalised novel immunogenomic biomarkers and (b) validate these biomarkers in various clinical scenarios in LSVH.

Lynch Syndrome Genetics and Clinical Implications

Lynch syndrome (LS) is one of the most prevalent hereditary cancer syndromes in humans and accounts for some 3% of unselected patients with colorectal or endometrial cancer and 10%-15% of those with DNA mismatch repair-deficient tumors. Previous studies have established the genetic basis of LS predisposition, but there have been significant advances recently in the understanding of the molecular pathogenesis of LS tumors, which has important implications in clinical management. At the same time, immunotherapy has revolutionized the treatment of advanced cancers with DNA mismatch repair defects. We aim to review the recent progress in the LS field and discuss how the accumulating epidemiologic, clinical, and molecular information has contributed to a more accurate and complete picture of LS, resulting in genotype- and immunologic subtype-specific strategies for surveillance, cancer prevention, and treatment.

A Pathogenic Variant Reclassified to the Pseudogene PMS2P1 in a Patient with Suspected Hereditary Cancer

The PMS2 gene is involved in DNA repair by the mismatch repair pathway. Deficiencies in this mechanism have been associated with Lynch Syndrome (LS), which is characterized by a high risk for colorectal, endometrial, ovarian, breast, and other cancers. Germinal pathogenic variants of PMS2 are associated with up to 5% of all cases of LS. The prevalence is overestimated for the existence of multiple homologous pseudogenes. We report the case of a 44-year-old woman diagnosed with breast cancer at 34 years without a relevant cancer family history. The presence of pathogenic variant NM_000535.7:c.1A > T, (p.Met1Leu) in PMS2 was determined by next-generation sequencing analysis with a panel of 322 cancer-associated genes and confirmed by capillary sequencing in the patient. The variant was determined in six family members (brothers, sisters, and a son) and seven non-cancerous unrelated individuals. Analysis of the amplified region showed high homology of PMS2 with five of its pseudogenes. We determined that the variant is associated with the PMS2P1 pseudogene following sequence alignment analysis. We propose considering the variant c.1A > T, (p.Met1Leu) in PMS2 for reclassification as not hereditary cancer-related, given the impact on the diagnosis and treatment of cancer patients and families carrying this variant.

Immune desert in MMR-deficient tumors predicts poor responsiveness of immune checkpoint inhibition

Background

Although many efforts have been devoted to identify biomarkers to predict the responsiveness of immune checkpoint inhibitors, including expression of programmed death-ligand 1 (PD-L1) and major histocompatibility complex (MHC) I, microsatellite instability (MSI), mismatch repair (MMR) defect, tumor mutation burden (TMB), tertiary lymphoid structures (TLSs), and several transcriptional signatures, the sensitivity of these indicators remains to be further improved.

Materials and methods

Here, we integrated T-cell spatial distribution and intratumor transcriptional signals in predicting the response to immune checkpoint therapy in MMR-deficient tumors including tumors of Lynch syndrome (LS).

Results

In both cohorts, MMR-deficient tumors displayed personalized tumor immune signatures, including inflamed, immune excluded, and immune desert, which were not only individual-specific but also organ-specific. Furthermore, the immune desert tumor exhibited a more malignant phenotype characterized by low differentiation adenocarcinoma, larger tumor sizes, and higher metastasis rate. Moreover, the tumor immune signatures associated with distinct populations of infiltrating immune cells were comparable to TLSs and more sensitive than transcriptional signature gene expression profiles (GEPs) in immunotherapy prediction. Surprisingly, the tumor immune signatures might arise from the somatic mutations. Notably, patients with MMR deficiency had benefited from the typing of immune signatures and later immune checkpoint inhibition.

Conclusion

Our findings suggest that compared to PD-L1 expression, MMR, TMB, and GEPs, characterization of the tumor immune signatures in MMR-deficient tumors improves the efficiency of predicting the responsiveness of immune checkpoint inhibition.

Systematic pan-cancer analysis of the potential tumor diagnosis and prognosis biomarker P4HA3

Purpose: Prolyl 4-hydroxylase subunit alpha 3 (P4HA3) is implicated in several cancers' development. However, P4HA3 has not been reported in other cancers, and the exact mechanism of action is currently unknown. Materials and methods: First, the expression profile of P4HA3 was analyzed using a combination of the University of California Santa Cruz (UCSC) database, Cancer Cell Line Encyclopedia (CCLE) database, and Genotype-Tissue Expression (GTEx) database. UniCox and Kaplan-Meier were used to analyze the predictive value of P4HA3. The expression of P4HA3 was analyzed in clinical staging, immune subtypes, and Molecular subtypes. Secondly, the correlation of P4HA3 with immunomodulatory genes, immune checkpoint genes, RNA modification genes, immune cell infiltration, cancer-related functional status, tumor stemness index, DNA mismatch repair (MMR) genes and DNA Methyltransferase was examined. The role of P4HA3 in DNA methylation, copy number variation (CNV), mutational status, tumor mutational burden (TMB), and microsatellite instability (MSI) was also analyzed. In addition, gene set enrichment analysis (GSEA) was used to explore the potential functional mechanisms of P4HA3 in pan-cancer. Finally, P4HA3-related drugs were searched in CellMiner, Genomics of Drug Sensitivity in Cancer (GDSC), and Cancer Therapeutics Response Portal (CTRP) databases. Results: P4HA3 is significantly overexpressed in most cancers and is associated with poor prognosis. P4HA3 is strongly associated with clinical cancer stage, immune subtypes, molecular subtypes, immune regulatory genes, immune checkpoint genes, RNA modifier genes, immune cell infiltration, cancer-related functional status, tumor stemness index, MMR Gene, DNA Methyltransferase, DNA methylation, CNV, mutational status, TMB, and MSI are closely related. Available enrichment analysis revealed that P4HA3 is associated with the epithelial-mesenchymal transition and immune-related pathways. There are currently 20 drugs associated with P4HA3. Conclusion: In human pan-cancer, P4HA3 is associated with poor patient prognosis and multiple immune cells and may be a novel immunotherapeutic target. It may act on tumor progression through the epithelial-mesenchymal transition (EMT) pathway.

Colorectal surveillance outcomes from an institutional longitudinal cohort of lynch syndrome carriers

Objective

Lynch Syndrome (LS) carriers have a significantly increased risk of developing colorectal cancer (CRC) during their lifetimes. Further stratification of this patient population may help in identifying additional risk factors that predispose to colorectal carcinogenesis. In most LS patients CRC may arise from adenomas, although an alternative non-polypoid carcinogenesis pathway has been proposed for PMS2 carriers. Using data from our institutional LS cohort, our aim was to describe our current colorectal screening outcomes with a focus on the incidence of adenomas in the context of different MMR genotypes and patient demographics such as gender, race, and ethnicity.

Design

We collected demographics, genetic, colonoscopy, and pathology results from a total of 163 LS carriers who obtained regular screening care at MD Anderson Cancer Center. Data were extracted from the electronic health records into a REDCap database for analysis. Logistic regressions were performed to measure the association between MMR variants and the likelihood of adenomas, advanced adenomas, and CRC. Then, we analyzed the cumulative incidences of these outcomes for the first 36 months following enrollment using Kaplan-Meier incidence curves, and Cox proportional hazard regressions.

Results

On multivariate analysis, age (≥45 years old) was associated with an increased risk of developing adenomas (P=0.034). Patients with a prior or active cancer status were less likely to develop adenomas (P=0.015), despite of the lack of association between surgical history with this outcome (P=0.868). We found no statistically significant difference in likelihood of adenoma development between MLH1 and MSH2/EPCAM, MSH6, and PMS2 carriers. Moreover, we observed no statistically significant difference in the likelihood of advanced adenomas or CRC for any measured covariates. On Cox proportional hazard, compared to MLH1 carriers, the incidence of adenomas was highest among MSH2/EPCAM carriers during for the first 36-months of follow-up (P<0.001). We observed a non-statistically significant trend for Hispanics having a higher and earlier cumulative incidence of adenomas compared to non-Hispanics (P=0.073). No MMR carrier was more likely to develop advanced adenomas. No difference in the incidence of CRC by MMR gene (P=0.198).

Conclusion

Screening recommendations for CRC in LS patients should be based on specific MMR variants and should also be tailored to consider patient demographics.

Hereditary breast cancer: syndromes, tumour pathology and molecular testing

Hereditary factors account for a significant proportion of breast cancer risk. Approximately 20% of hereditary breast cancers are attributable to pathogenic variants in the highly penetrant BRCA1 and BRCA2 genes. A proportion of the genetic risk is also explained by pathogenic variants in other breast cancer susceptibility genes, including ATM, CHEK2, PALB2, RAD51C, RAD51D and BARD1, as well as genes associated with breast cancer predisposition syndromes - TP53 (Li-Fraumeni syndrome), PTEN (Cowden syndrome), CDH1 (hereditary diffuse gastric cancer), STK11 (Peutz-Jeghers syndrome) and NF1 (neurofibromatosis type 1). Polygenic risk, the cumulative risk from carrying multiple low-penetrance breast cancer susceptibility alleles, is also a well-recognised contributor to risk. This review provides an overview of the established breast cancer susceptibility genes as well as breast cancer predisposition syndromes, highlights distinct genotype-phenotype correlations associated with germline mutation status and discusses molecular testing and therapeutic implications in the context of hereditary breast cancer.

Concurrent intraventricular intracranial myxoid mesenchymal tumor and ependymoma in a long-term Ewing sarcoma survivor

Intracranial myxoid mesenchymal tumor, FET::CREB fusion positive is a rare, recently described central nervous system neoplasm. It is characterized by EWSR1::CREB family transcription factor fusion, typically arises in children and adolescents, and is locally aggressive even after gross total resection. Currently, there are little data available to guide management and gauge long-term prognosis. Furthermore, there have been no reports of these lesions occurring simultaneously with other intracranial neoplasms or in patients with a history of malignancy. Here we describe the first case of a very unusual patient with intracranial myxoid mesenchymal tumor of the right lateral ventricle with a concurrent fourth ventricular ependymoma who had a remote history of Ewing sarcoma of the right fibula.

Biomarkers in the development of individualized treatment regimens for colorectal cancer

Introduction

Colorectal cancer (CRC) is the third most common and second most deadly malignancy in the world with an estimated 1. 9 million cases and 0.9 million deaths in 2020. The 5-year overall survival for stage I disease is 92% compared to a dismal 11% in stage IV disease. At initial presentation, up to 35% of patients have metastatic colorectal cancer (mCRC), and 20–50% of stage II and III patients eventually progress to mCRC. These statistics imply both that there is a proportion of early stage patients who are not receiving adequate treatment and that we are not adequately treating mCRC patients.

Body

Targeted therapies directed at CRC biomarkers are now commonly used in select mCRC patients. In addition to acting as direct targets, these biomarkers also could help stratify which patients receive adjuvant therapies and what types. This review discusses the role of RAS, microsatellite instability, HER2, consensus molecular subtypes and ctDNA/CTC in targeted therapy and adjuvant chemotherapy.

Discussion

Given the relatively high recurrence rate in early stage CRC patients as well as the continued poor survival in mCRC patients, additional work needs to be done beyond surgical management to limit recurrence and improve survival. Biomarkers offer both a potential target and a predictive method of stratifying patients to determine those who could benefit from adjuvant treatment.

Improved NGS-based detection of microsatellite instability using tumor-only data

Microsatellite instability (MSI) is a molecular signature of mismatch repair deficiency (dMMR), a predictive marker of immune checkpoint inhibitor therapy response. Despite its recognized pan-cancer value, most methods only support detection of this signature in colorectal cancer. In addition to the tissue-specific differences that impact the sensitivity of MSI detection in other tissues, the performance of most methods is also affected by patient ethnicity, tumor content, and other sample-specific properties. These limitations are particularly important when only tumor samples are available and restrict the performance and adoption of MSI testing. Here we introduce MSIdetect, a novel solution for NGS-based MSI detection. MSIdetect models the impact of indel burden and tumor content on read coverage at a set of homopolymer regions that we found are minimally impacted by sample-specific factors. We validated MSIdetect in 139 Formalin-Fixed Paraffin-Embedded (FFPE) clinical samples from colorectal and endometrial cancer as well as other more challenging tumor types, such as glioma or sebaceous adenoma or carcinoma. Based on analysis of these samples, MSIdetect displays 100% specificity and 96.3% sensitivity. Limit of detection analysis supports that MSIdetect is sensitive even in samples with relatively low tumor content and limited microsatellite instability. Finally, the results obtained using MSIdetect in tumor-only data correlate well (R=0.988) with what is obtained using tumor-normal matched pairs, demonstrating that the solution addresses the challenges posed by MSI detection from tumor-only data. The accuracy of MSI detection by MSIdetect in different cancer types coupled with the flexibility afforded by NGS-based testing will support the adoption of MSI testing in the clinical setting and increase the number of patients identified that are likely to benefit from immune checkpoint inhibitor therapy.

The prevalence of germline pathogenic variants in Estonian colorectal cancer patients: results from routine clinical setting 2016-2021

Background: Colorectal cancer (CRC) is the third most common cancer in Estonia in both women and men. According to the Estonian National Institute for Health Development, in 2017, there were 357 new colon cancer only cases in women and 282 in men. For colorectal cancer, the number for men and women altogether was 1040 in the same year. In 2018, there were over 1.8 million new cases worldwide. The Mayo Clinic found in a prospective, two-year multi-site study of CRC patients that 15.5% of patients carried pathogenic germline variants (PGV), using an >80 gene Next Generation Sequencing (NGS) panel. Material and methods: This retrospective study aimed to analyse the estimated prevalence of pathogenic/likely pathogenic germline variants in Estonian colorectal cancer patients using NGS in a routine clinical setting. We gathered five-year data (July 2016-July 2021) of colorectal cancer patients (mostly not selected for age or family history) tested with either Illumina TruSight Cancer (94 genes) or TruSight Hereditary Cancer (113 genes) NGS panels. Results: Three hundred and fourteen NGS analyses were performed due to either CRC or polyposis in anamnesis and/or family anamnesis, including 126 CRC cases and 44 colorectal polyposis cases, while 144 were either healthy family members or had other types of cancers. While a known disease-causing variant was identified in 16.4% of all cancer patients tested, we found that 21.4% of CRC patients had such a variant. Among the 44 colorectal polyps cases MLH1, gene was the most affected one (25%), the second and third most affected genes were MSH2 and CHEK2. Other genes with disease-causing variants found in CRC patients included APC, BLM, BMPR1A, BRCA1, FANCM, MSH6, MUTYH, PMS2, SMAD4, SPINK1 and VHL. Conclusion: Our result give an overview of genetic testing of CRC patients, the prevalence of disease-causing variants and their landscape in Estonia. According to Estonian data, only 2.7-6.1% of CRC patients are genetically tested, which is around ten times less frequently than breast cancer patients and their family members. The diagnostic yield of CRC patients is 21.4%, suggesting that genetic testing will likely improve timely diagnosis and outcomes.

Overview of predictive and prognostic biomarkers and their importance in developing a clinical pharmacology treatment plan in colorectal cancer patients

INTRODUCTION

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Although overall survival for CRC patients has improved with earlier screening, survival continues to vary substantially across stages. Also, while the introduction of targeted therapies, including VEGF and EGFR inhibitors, has contributed to improving survival, better tools are needed to optimize patient selection and maximize therapeutic benefits. Emerging biomarkers can be used to guide pharmacologic decision-making, as well as monitor treatment response, clarify the need for adjuvant therapies, and indicate early signs of recurrence. This is a narrative review examining the current and evolving use of predictive and prognostic biomarkers in colorectal cancer.

AREAS COVERED

Areas covered include mutations of the MAPK (KRAS, BRAF) and HER2 pathways and their impacts on treatment decisions. In addition, novel methods for assessing tumor mutations and tracking treatment responses are examined.

EXPERT OPINION

The standard of care pathway for staging, and treatment selection and surveillance, of CRC will expand to include novel biomarkers in the next 5 years. It is anticipated that these new biomarkers will assist in decision-making regarding selection of targeted therapies and, importantly, in risk stratification for treatment decisions in patients at high risk for recurrence.

Scalable detection of technically challenging variants through modified next-generation sequencing

BACKGROUND

Some clinically important genetic variants are not easily evaluated with next-generation sequencing (NGS) methods due to technical challenges arising from high- similarity copies (e.g., PMS2, SMN1/SMN2, GBA1, HBA1/HBA2, CYP21A2), repetitive short sequences (e.g., ARX polyalanine repeats, FMR1 AGG interruptions in CGG repeats, CFTR poly-T/TG repeats), and other complexities (e.g., MSH2 Boland inversions).

METHODS

We customized our NGS processes to detect the technically challenging variants mentioned above with adaptations including target enrichment and bioinformatic masking of similar sequences. Adaptations were validated with samples of known genotypes.

RESULTS

Our adaptations provided high-sensitivity and high-specificity detection for most of the variants and provided a high-sensitivity primary assay to be followed with orthogonal disambiguation for the others. The sensitivity of the NGS adaptations was 100% for all of the technically challenging variants. Specificity was 100% for those in PMS2, GBA1, SMN1/SMN2, and HBA1/HBA2, and for the MSH2 Boland inversion; 97.8%-100% for CYP21A2 variants; and 85.7% for ARX polyalanine repeats.

CONCLUSIONS

NGS assays can detect technically challenging variants when chemistries and bioinformatics are jointly refined. The adaptations described support a scalable, cost-effective path to identifying all clinically relevant variants within a single sample.

A Previously Unrecognized Molecular Landscape of Lynch Syndrome in the Mexican Population

Lynch syndrome (LS) is the main hereditary colorectal cancer syndrome. There have been few reports regarding the clinical and molecular characteristics of LS patients in Latin America; this is particularly true in the Mexican population, where no information is available. The present study aims to describe the clinical and molecular spectrum of variants in a cohort of patients diagnosed with LS in Mexico. We present a retrospective analysis of 412 patients with suspected LS, whose main site of cancer diagnosis was the colon (58.25%), followed by the endometrium (18.93%). Next-generation sequencing analysis, with an extensive multigene panel, showed that 27.1% (112/414) had a variant in one of the genes of the mismatch repair pathway (MMR); 30.4% (126/414) had a variant in non-MMR genes such as CHEK2, APC, MUTYH, BRCA1, and BRCA2; and 42.5% (176/414) had no genetic variants. Most of the variants were found in MLH1. Pathogenic variants (PVs) in MMR genes were identified in 65.7% (96/146) of the total PVs, and 34.24% (45/146) were in non-MMR genes. Molecular and clinical characterization of patients with LS in specific populations allowed personalized follow-up, with the option for targeted treatment with immune checkpoint inhibitors and the development of public health policies. Moreover, such characterization allows for family cascade testing and consequent prevention strategies.

PD-1 blockage combined with vaccine therapy can facilitate immune infiltration in tumor microenvironment of Lynch syndrome colon cancer

Background: Lynch syndrome is a genetic disease resulting from mismatch repair gene mutation. Vaccine therapy can enhance the immunogenicity of Lynch syndrome and improve the therapeutic efficacy of immunotherapy. However, there is no approved Lynch syndrome vaccine coming onto the market.

Methods: Herein, we used gene knockdown method to construct Lynch syndrome cell model, paving way for us to develop Lynch syndrome tumor lysate vaccine. Then the isograft technique was employed for constructing the tumor-bearing mouse model of Lynch syndrome. And this isograft model was treated with PD-1 monoclonal antibody and tumor vaccine, respectively. Flow cytometry was used for detecting the proportion of immune cells and immunosuppressive cells, and ELISA was used for detecting the contents of chemokines and cytokines in the blood circulation system and tumor tissues of mice. Finally, IHC was used to detect the effects of tumor vaccines as well as PD-1 antibody on tumor tissue proliferation and angiogenesis.

Results: The results demonstrated that tumor vaccine could prolong the overall survival of mice, and improve the disease-free survival rate of mice. The vaccine could increase the proportion of inflammatory cells and decrease the proportion of anti-inflammatory cells in the blood circulation system of mice. In addition, tumor vaccine could also improve inflammatory infiltration in the tumor microenvironment and reduce the proportion of immunosuppressive cells. The results of IHC showed that tumor vaccine could inhibit angiogenesis and tumor cell proliferation in mouse tumor tissues.

Conclusion: In colon cancer associated with Lynch syndrome, tumor vaccine can hinder the growth of tumor cells, and assist immunotherapy whose therapeutic effect on this kind of cancer is thus enhanced.

Surgical management of a solitary metastatic ovarian adenocarcinoma with colonic origin presenting as gigantic bilateral ovarian masses

Metastatic ovarian tumors with a gastrointestinal origin have always been a challenge in surgery; in many cases, the primary tumor is diagnosed after the metastasis. This case was presented with bilateral abdominal masses, which were adenocarcinomas originating from gastrointestinal tract. Following colonoscopy and finding a mass, total colectomy was performed.

The key clinical message, in this case, is that large, bilateral masses in the absence of ascites are suggestive for an extragonadal origin for which one of the primary sources is GI, so endoscopy and colonoscopy should be carried out for these patients (for gastric and colonic cancers). Resecting the primary tumor with metastasis is controversial, and not currently enough data are available. Our assumption is that we have to rule out the secondary sites of metastasis and peritoneal seeding, for which palliative chemotherapy and ostomy diversion for obstructive cases is the only option. In cases with no secondary site of metastasis surgery is considered an option, but the risk of metachronous metastasis is high, and the prognosis is poor.