Mechanisms of immunogenicity in colorectal cancer

Background

The immune response in cancer is increasingly understood to be important in determining clinical outcomes, including responses to cancer therapies. New insights into the mechanisms underpinning the immune microenvironment in colorectal cancer are helping to develop the role of immunotherapy and suggest targeted approaches to the management of colorectal cancer at all disease stages.

Method

A literature search was performed in PubMed, MEDLINE and Cochrane Library databases to identify relevant articles. This narrative review discusses the current understanding of the contributors to immunogenicity in colorectal cancer and potential applications for targeted therapies.

Results

Responsiveness to immunotherapy in colorectal cancer is non-uniform. Several factors, both germline and tumour-related, are potential determinants of immunogenicity in colorectal cancer. Current approaches target tumours with high immunogenicity driven by mutations in DNA mismatch repair genes. Recent work suggests a role for therapies that boost the immune response in tumours with low immunogenicity.

Conclusion

With the development of promising therapies to boost the innate immune response, there is significant potential for the expansion of the role of immunotherapy as an adjuvant to surgical treatment in colorectal cancer.

Epigenetic biomarkers in progression from non-dysplastic Barrett's oesophagus to oesophageal adenocarcinoma: a systematic review protocol

INTRODUCTION

Barrett's oesophagus (BO), a metaplastic condition affecting the lower oesophagus due to long-standing gastro-oesophageal reflux and chronic inflammation, is a precursor lesion for oesophageal adenocarcinoma (OADC). There is no clinical test to predict which patients with BO will progress to OADC. The British Society of Gastroenterology recommends endoscopic surveillance of patients with BO. Epigenetic changes have been well characterised in the neoplastic progression of ulcerative colitis to colonic carcinoma, another gastrointestinal cancer associated with chronic inflammation. This systematic review protocol aims to identify and evaluate studies which examine epigenetic biomarkers in BO and their association with progression to OADC.

METHODS AND ANALYSIS

All prospective and retrospective primary studies, and existing systematic reviews investigating epigenetic markers including DNA methylation, histone modification, chromatin remodelling, micro and non-coding RNAs of all types will be eligible for inclusion. Eligible patients are those over the age of 18 with BO, BO with dysplasia, OADC or unspecified oesophageal cancer. A comprehensive search of bibliographic databases using combinations of text and index words relating to the population, prognostic markers and outcome will be undertaken with no language restrictions. Results will be screened by 2 independent reviewers and data extracted using a standardised proforma. The quality and risk of bias of individual studies will be assessed using the Quality in Prognostic Studies (QUIPS) tool. A narrative synthesis of all evidence will be performed with key findings tabulated. Meta-analysis will be considered where studies and reported outcomes are considered sufficiently homogeneous, both clinically and methodologically. Findings will be interpreted in the context of the quality of included studies. The systematic review will be reported according to PRISMA guidelines.

ETHICS AND DISSEMINATION

This is a systematic review of completed studies and no ethical approval is required. Findings from the full systematic review will be submitted for publication and presentation at national and international conferences which will inform future research on risk stratification in patients with BO.

REVIEW REGISTRATION NUMBER

CRD42016038654.

Surgery in the era of the 'omics revolution

Background

Surgery is entering a new phase with the revolution in genomic technology. Cheap, mass access to next‐generation sequencing is now allowing the analysis of entire human genomes at the DNA and RNA level. These data sets are being used increasingly to identify the molecular differences that underlie common surgical diseases, and enable them to be stratified for patient benefit.

Methods

This article reviews the recent developments in the molecular biology of colorectal, oesophagogastric and breast cancer.

Results

The review specifically covers developments in genetic predisposition, next‐generation sequencing studies, biomarkers for stratification, prognosis and treatment, and other 'omics technologies such as metabolomics and proteomics.

Conclusion

There are unique opportunities over the next decade to change the management of surgical disease radically, using these technologies. The directions that this may take are highlighted, including future advances such as the 100 000 Genomes Project.

May individualize cancer treatment

Expression and DNA methylation of TNF, IFNG and FOXP3 in colorectal cancer and their prognostic significance

BACKGROUND

Colorectal cancer (CRC) progression is associated with suppression of host cell-mediated immunity and local immune escape mechanisms. Our aim was to assess the immune function in terms of expression of TNF, IFNG and FOXP3 in CRC.

METHODS

Sixty patients with CRC and 15 matched controls were recruited. TaqMan quantitative PCR and methylation-specific PCR was performed for expression and DNA methylation analysis of TNF, IFNG and FOXP3. Survival analysis was performed over a median follow-up of 48 months.

RESULTS

TNF was suppressed in tumour and IFNG was suppressed in peripheral blood mononuclear cells (PBMCs) of patients with CRC. Tumours showed enhanced expression of FOXP3 and was significantly higher when tumour size was >38 mm (median tumour size; P=0.006, Mann-Whitney U-test). Peripheral blood mononuclear cell IFNG was suppressed in recurrent CRC (P=0.01). Methylated TNFpromoter (P=0.003) and TNFexon1 (P=0.001) were associated with significant suppression of TNF in tumours. Methylated FOXP3cpg was associated with significant suppression of FOXP3 in both PBMC (P=0.018) and tumours (P=0.010). Reduced PBMC FOXP3 expression was associated with significantly worse overall survival (HR=8.319, P=0.019).

CONCLUSIONS

We have detected changes in the expression of immunomodulatory genes that could act as biomarkers for prognosis and future immunotherapeutic strategies.

A study of genomic instability in early preneoplastic colonic lesions

It is difficult to explain the differential rates of progression of premalignant colonic lesions and differences in behaviour of morphologically similar lesions. Heterogeneity for microsatellite instability (MSI) and promoter methylation in driving these phenomena forward may explain this; however, no previous analysis has examined this in detail at the gland level, the smallest unit of colorectal premalignant lesions. We aimed to carry out an analysis of gland level genomic instability for MSI and promoter methylation. MSI occurred significantly more frequently (20%) in colonic glands than has previously been observed in whole colorectal polyps. Significant promoter methylation was seen in MLH1, PMS2, MLH3 and MSH3 as well as significant heterogeneity for both MSI and promoter methylation. Methylation and MSI may have a significant role in driving forward colorectal carcinogenesis, although in the case of MSI, this association is less clear as it occurs significantly more frequently than previously thought, and may simply be a passenger in the adenoma-carcinoma sequence. Promoter methylation in MLH1, MLH3, MSH3 and PMS2 was also found to be significantly associated with MSI and should be investigated further. A total of 273 colorectal glands (126 hyperplastic, 147 adenomatous) were isolated via laser capture microdissection (targeted at regions of MLH1 loss) from 93 colonic polyps and tested for MSI, and promoter methylation of the DNA mismatch repair genes MLH1, MSH2, MLH3, MSH6, PMS2, MGMT and MLH3 via methylation specific multiplex ligation-dependent probe amplification. Logistic regression modelling was then used to identify significant associations between promoter methylation and gland histological type and MSI status.

TERC polymorphisms are associated both with susceptibility to colorectal cancer and with longer telomeres

BACKGROUND AND AIMS

Shorter telomeres have been associated with increased risk of malignancy, including colorectal cancer (CRC). Telomere length is heritable and may be an intermediate phenotype linked to genetic susceptibility to CRC.

METHODS

In a large sample, the study investigated whether candidate single nucleotide polymorphisms (SNP) in 'telomere biology' genes were associated with telomere length in leucocytes. SNP associated with an increased risk of CRC were searched for separately.

RESULTS

Carriers of the common allele at SNP rs10936599, near the telomerase RNA component (TERC) locus, had significantly longer telomeres. It was independently found that the same rs10936599 allele was associated with increased risk of both CRC and colorectal adenomas. Neither telomere length nor CRC risk was associated with variation near telomerase reverse transcriptase or other telomere biology genes. In silico analysis showed that SNP rs2293607 was strongly correlated with rs10936599, mapped within TERC transcripts, had a predicted effect on messenger RNA folding and lay at a reported transcription factor binding site. TERC mRNA were expressed, differing only at the alleles of rs2293607, in CRC cell line HCT116. The long-telomere/CRC-risk allele was associated with higher levels of TERC mRNA and the formation of longer telomeres.

CONCLUSIONS

Common genetic variation at TERC is associated with both longer telomeres and an increased risk of CRC, a potential mechanism being reduced levels of cell senescence or death. This finding is somewhat paradoxical, given retrospective studies reporting that CRC cases have shorter telomeres than controls. One possibility is that that association actually results from poorer survival in patients with longer telomeres.

A pilot study of ultrasound guided Durasphere injection in the treatment of faecal incontinence

AIM

To assess injection of Durasphere under direct endoanal ultrasound guidance as a treatment for faecal incontinence.

METHOD

A total of 23 patients with varying degrees of persistent faecal leakage and/or soiling were recruited. Durasphere was injected in the intersphincteric plane under direct ultrasound guidance. All patients were given a general anaesthetic. Patients had ano-rectal physiology, endoanal ultrasound, continence scoring and quality of life measures assessed at 0, 1, 3, 6 and 12 months.

RESULTS

A total of 21 patients were followed up for at least 12 months, with two being excluded at the follow-up stage. Friedman two-way analysis of variance of the Cleveland Clinic Score, Faecal Incontinence Quality of Life Score and Diary Response Score demonstrated a significant sustained improvement. There was no significant improvement in number of bowel movements. There was a significant difference in anal squeeze pressure after therapy, but no significant difference in anal resting pressure. Six patients reported no improvement after Durasphere therapy.

CONCLUSIONS

Durasphere gave sustained improvements in quality of life and continence scores in this study group. Strict criteria are needed to ascertain suitability for Durasphere therapy.

Peutz-Jeghers syndrome: a systematic review and recommendations for management

Peutz-Jeghers syndrome (PJS, MIM175200) is an autosomal dominant condition defined by the development of characteristic polyps throughout the gastrointestinal tract and mucocutaneous pigmentation. The majority of patients that meet the clinical diagnostic criteria have a causative mutation in the STK11 gene, which is located at 19p13.3. The cancer risks in this condition are substantial, particularly for breast and gastrointestinal cancer, although ascertainment and publication bias may have led to overestimates in some publications. Current surveillance protocols are controversial and not evidence-based, due to the relative rarity of the condition. Initially, endoscopies are more likely to be done to detect polyps that may be a risk for future intussusception or obstruction rather than cancers, but surveillance for the various cancers for which these patients are susceptible is an important part of their later management. This review assesses the current literature on the clinical features and management of the condition, genotype-phenotype studies, and suggested guidelines for surveillance and management of individuals with PJS. The proposed guidelines contained in this article have been produced as a consensus statement on behalf of a group of European experts who met in Mallorca in 2007 and who have produced guidelines on the clinical management of Lynch syndrome and familial adenomatous polyposis.

FDG-PET as a "metabolic biopsy" tool in non-lung lesions with indeterminate biopsy

The differentiation of benign versus malignant disease in a lesion identified on conventional imaging is a commonly encountered problem. Attempted biopsy is often unsuccessful or falsely reassuring and may lead to the patient being sent for more invasive and potentially morbid investigations. Having previously identified the value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in this circumstance in patients with lung lesions, our current aim was to investigate the role of FDG-PET in helping to identify more accurately those patients with malignant lesions outside the lung. FDG-PET scanning was performed in 50 patients; most had undergone unsuccessful biopsy of a lesion outside the lung, while in a smaller number no attempt at biopsy had been made as it had been considered too dangerous. Follow-up was by histology or, if this was unavailable, by clinical progress to death or a minimum of 12 months post scan. Visual and quantitative analysis was performed. On visual analysis, the positive and negative predictive values were 89% and 100%, respectively. On quantitative (SUV>2.5) analysis, positive and negative predictive values were 93% and 86%, respectively. A negative FDG-PET study in these circumstances virtually excludes malignancy and allows the patient to be reassured. A positive scan encourages the clinician to pursue further biopsy to confirm a histological diagnosis. FDG-PET therefore assists in deciding which patients need to undergo further investigation.

FDG-PET as a "metabolic biopsy" tool in thoracic lesions with indeterminate biopsy

A common problem encountered in clinical medicine is the classification of a lung lesion (nodule/opacity) on conventional imaging. Often attempts at biopsy are unsuccessful or are falsely reassuring, and the decision to send the patient for more invasive and potentially morbid procedures can be difficult. Our aim was to investigate the role of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in helping to identify more accurately those patients with malignant lesions. Sixty-three patients underwent FDG-PET scans following unsuccessful biopsy of a lung lesion or, in a lesser number of cases, when an attempt at biopsy was considered too dangerous. Follow-up was by histology or, if this was unavailable, by clinical progress to death or a minimum of 18 months post scan. Visual and quantitative analysis was performed. On visual analysis, positive and negative predictive values were 90% and 100%, respectively. On quantitative (SUV>2.5) analysis, positive and negative predictive values were 90% and 85%, respectively. We interpret these results as showing that the use of FDG-PET scans in patients in this circumstance is non-invasive and highly sensitive in diagnosing malignancy. The high positive predictive value suggests that those with a positive scan must undergo further investigation, while the 100% negative predictive value means those with no FDG uptake can safely be spared further invasive investigations