The evolution of colorectal cancer genetics-Part 1: from discovery to practice

Validation of Faecal Pyruvate Kinase Isoenzyme Type M2 (Faecal M2PK Quick) Test in Detection of Colorectal Adenoma and Adenocarcinoma Among High-Risk Malaysian Population

BACKGROUND

Colorectal neoplasia is a multistep process that can lead to the development of colorectal cancer. Colonoscopy is the gold standard for diagnosis and screening of colorectal cancer, but its uptake is often hindered by unpleasant experiences and logistic obstacles. Therefore, non-invasive biomarker tests such as the M2-pyruvate kinase (M2PK) test have been explored as a potential screening tool.

OBJECTIVE

This study aims to evaluate the efficacy of the M2PK Quick Stool Test (ScheBo®) in detecting colorectal adenoma and adenocarcinoma in high-risk Malaysian populations using colonoscopy as the comparison.

METHODS

A prospective, cross-sectional, multicenter study was conducted from December 2017 to December 2019 in four hospitals in Malaysia. Participants were eligible if they met any of the following criteria: personal or family history of colorectal polyps or cancer, inherited syndromes, altered bowel habits, rectal bleeding, unintended weight loss, loss of appetite, abdominal pain or cramps, or unexplained iron deficiency, or an Asia-Pacific Colorectal Screening score of 4-7. Participants provided a stool sample that was tested for M2PK using the M2PK Quick Test. Participants then underwent a colonoscopy, and any lesions found were biopsied and sent for histopathological examination.

RESULTS

A total of 562 participants were included in the study, of whom 89 had a positive M2PK test. Presence of adenoma and/or dysplastic lesions were confirmed in 14.4% and adenocarcinoma in 3.0% of the participants. The M2PK Quick Stool Test showed a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 58.8%, 85.5%, 11.2% and 98.5%, respectively in detecting colorectal adenocarcinoma. For detection of colorectal adenoma, this test yielded a sensitivity, specificity, PPV and NPV of 27.3%, 86.3%, 27.0% and 86.5%, respectively.

CONCLUSIONS

The M2PK Quick Stool Test showed a moderate accuracy in detecting colorectal adenocarcinoma and adenomas in the studied population.

Overview of microRNAs as liquid biopsy biomarkers for colorectal cancer sub-type profiling and chemoresistance

Colorectal cancer (CRC) is the third most common cancer worldwide. It has also been demonstrated that over the last ten years the incidence of CRC among younger people below the age of 50 is also increasing. Screening for colorectal cancer is of utmost importance; the rationale behind screening is to target the malignancy and reduce the incidence and mortality of the disease. Diagnostic methods to screen for incidence or relapse are therefore a requisite to detect cancer as early as possible. Scientific findings demonstrate that many deaths are due to lack of screening and therefore early identification will lead to greater survivability. In colorectal cancer, diagnostic tests include liquid biopsy biomarkers. Since the discovery of microRNAs (miRNAs), many studies have demonstrated the relationship between miRNAs and the various sub-types of CRC. Several miRNAs have been identified after analysing serum or plasma samples in patients, and such miRNAs were found to be significantly dysregulated. Such findings place the possibility of miRNAs to be at the epicentre of novel diagnostic techniques for CRC identification and sub-type stratification, including other characteristics associated with CRC development such as patient prognosis. The following review serves to underline the latest findings for miRNAs with such potential for routine diagnostic employment in CRC diagnostics and treatments.

In Vivo Anti Cancer Potential of Pyrogallol in Murine Model of Colon Cancer

Background: Colon cancer is aggressive and it causes 0.5 million deaths per year. Practicing natural medicines for cancer treatment is safer than conventional drugs. World health organization emphasizes on the importance of practicing natural medicines and developing natural product based drugs for cancer treatment. Recently we reported an anti colon cancer activity associated with pyrogallol isolated from medicinal plant Acacia nilotica in HT-29 cells in vitro. To extend our observation in this study we evaluated in vivo colon tumor remission property of acetone extract of A. nilotica (ACE) and pyrogallol. Materials and Methods: In vivo toxicity of ACE and pyrogallol was assessed and In vivo tumor remission activity of ACE and pyrogallol was determined in murine model. Results: Mice were tolerated different doses of ACE and pyrogallol. Tumor size was considerably reduced in pyrogallol treated mice similar to doxorubicin. Tumor bearing mice treated with ACE and pyrogallol showed mild decline in body weight. Conclusion: Pyrogallol was found to be an effective anti colon cancer agent with less toxicity.

An E-Learning Module to Improve Nongenetic Health Professionals' Assessment of Colorectal Cancer Genetic Risk: Feasibility Study

BACKGROUND

Nongenetic health providers may lack the relevant knowledge, experience, and communication skills to adequately detect familial colorectal cancer (CRC), despite a positive attitude toward the assessment of history of cancer in a family. Specific training may enable them to more optimally refer patients to genetic counseling.

OBJECTIVE

The aim of this study was to develop an e-learning module for gastroenterologists and surgeons (in training) aimed at improving attitudes, knowledge, and comprehension of communication skills, and to assess the feasibility of the e-learning module for continued medical education of these specialists.

METHODS

A focus group helped to inform the development of a training framework. The e-learning module was then developed, followed by a feasibility test among a group of surgeons-in-training (3rd- and 4th-year residents) and then among gastroenterologists, using pre- and posttest questionnaires.

RESULTS

A total of 124 surgeons-in-training and 14 gastroenterologists participated. The e-learning was positively received (7.5 on a scale of 1 to 10). Between pre- and posttest, attitude increased significantly on 6 out of the 10 items. Mean test score showed that knowledge and comprehension of communication skills improved significantly from 49% to 72% correct at pretest to 67% to 87% correct at posttest.

CONCLUSIONS

This study shows the feasibility of a problem-based e-learning module to help surgeons-in-training and gastroenterologists in recognizing a hereditary predisposition in patients with CRC. The e-learning led to improvements in attitude toward the assessment of cancer family history, knowledge on criteria for referral to genetic counseling for CRC, and comprehension of communication skills.

Development of a new analog of SGK1 inhibitor and its evaluation as a therapeutic molecule of colorectal cancer

Colorectal cancer (CRC) is one of the most leading causes of cancer-related death worldwide. The serum and glucocorticoid inducible kinase SGK1 is highly expressed and involved in several tumors. GSK650394, a SGK1 inhibitor, has been proved to be effective in impeding tumor growth in vitro. In this study, we developed a novel analog of GSK650394, and evaluated its effects on CRC cells and tumor growth both in vitro and in vivo. HCT116 cells were treated with a concentration gradient of new developed compounds and cholecystokinin octapeptide (CCK-8) assay was used to calculate the IC50 value of every analog. Cell proliferation analysis was estimated from EdU staining and flow cytometry in vitro, and immunohistochemistry of Ki67 and PCNA in vivo. Cell migration analysis was examined using the transwell assay. In vivo tumor growth was determined in athymic nude mice by injecting the HCT116 cells in the subcutaneous tissue, followed by the injection of QGY-5-114-A. We found that new developed GSK650394 analog QGY-5-114-A has lower IC50 value, and treatment with QGY-5-114-A significantly inhibited CRC cell proliferation and migration in vitro. Besides that, colonic tumor growth was also dramatically restricted by QGY-5-114-A in vivo. In conclusion, pharmacological treatment with QGY-5-114-A impedes CRC tumor cell proliferation, migration and tumor growth.

Gatekeeper role of gastroenterologists and surgeons in recognising and discussing familial colorectal cancer

This study aimed to gain insight into the gatekeeper role of surgeons and gastroenterologists (including residents) during a first consultation at a tertiary gastro-intestinal centre regarding referral for genetic counselling, and to test the feasibility of a checklist for indications for referral. Consecutive patients were invited before and after introduction of a checklist, to complete a questionnaire assessing their perception of discussing cancer genetic topics. Initial consultations were audiotaped to assess the quality of this discussion by gastroenterologists and surgeons. Data on completeness of the checklist and referral were collected from medical files. No significant differences were found between the Before and After group regarding patients’ reports of discussing cancer in the family (77 %, n = 34 vs 89 %, n = 33, p = 0.16). In 28 % (n = 10) of the audiotaped consultations family history was adequately discussed, in 58 % (n = 21) it was considered inadequate and in 14 % (n = 5) of consultations it was not discussed at all. A checklist was present in 53 % (n = 27) of the medical files. Of these, 5 (19 %) were incomplete. Gastroenterologists and surgeons (in training) have difficulty in fulfilling their gatekeeper role of recognizing patients at familial risk for CRC. Although they often discuss familial cancer during the initial consultation, their exploration seems insufficient to reveal indications for referral for genetic counselling. Therefore, healthcare professionals should not only understand genetics and the importance of cancer family history, but also be effective in the communication of this subject to enable more adequate referral of patients for genetic counselling.

Targeting colorectal cancer via its microenvironment by inhibiting IGF-1 receptor-insulin receptor substrate and STAT3 signaling

The tumor microenvironment (TME) exerts critical pro-tumorigenic effects through cytokines and growth factors that support cancer cell proliferation, survival, motility and invasion. Insulin-like growth factor-1 (IGF-1) and signal transducer and activator of transcription 3 (STAT3) stimulate colorectal cancer development and progression via cell autonomous and microenvironmental effects. Using a unique inhibitor, NT157, which targets both IGF-1 receptor (IGF-1R) and STAT3, we show that these pathways regulate many TME functions associated with sporadic colonic tumorigenesis in CPC-APC mice, in which cancer development is driven by loss of the Apc tumor suppressor gene. NT157 causes a substantial reduction in tumor burden by affecting cancer cells, cancer-associated fibroblasts (CAF) and myeloid cells. Decreased cancer cell proliferation and increased apoptosis were accompanied by inhibition of CAF activation and decreased inflammation. Furthermore, NT157 inhibited expression of pro-tumorigenic cytokines, chemokines and growth factors, including IL-6, IL-11 and IL-23 as well as CCL2, CCL5, CXCL7, CXCL5, ICAM1 and TGFβ; decreased cancer cell migratory activity and reduced their proliferation in the liver. NT157 represents a new class of anti-cancer drugs that affect both the malignant cell and its supportive microenvironment.

Germline Analysis from Tumor-Germline Sequencing Dyads to Identify Clinically Actionable Secondary Findings

PURPOSE

To evaluate germline variants in hereditary cancer susceptibility genes among unselected cancer patients undergoing tumor-germline sequencing.

EXPERIMENTAL DESIGN

Germline sequence data from 439 individuals undergoing tumor-germline dyad sequencing through the LCCC1108/UNCseq™ (NCT01457196) study were analyzed for genetic variants in 36 hereditary cancer susceptibility genes. These variants were analyzed as an exploratory research study to determine whether pathogenic variants exist within the germline of patients undergoing tumor-germline sequencing. Patients were unselected with respect to indicators of hereditary cancer predisposition.

RESULTS

Variants indicative of hereditary cancer predisposition were identified in 19 (4.3%) patients. For about half (10/19), these findings represent new diagnostic information with potentially important implications for the patient and their family. The others were previously identified through clinical genetic evaluation secondary to suspicion of a hereditary cancer predisposition. Genes with pathogenic variants included ATM, BRCA1, BRCA2, CDKN2A, and CHEK2 In contrast, a substantial proportion of patients (178, 40.5%) had Variants of Uncertain Significance (VUS), 24 of which had VUS in genes pertinent to the presenting cancer. Another 143 had VUS in other hereditary cancer genes, and 11 had VUS in both pertinent and nonpertinent genes.

CONCLUSIONS

Germline analysis in tumor-germline sequencing dyads will occasionally reveal significant germline findings that were clinically occult, which could be beneficial for patients and their families. However, given the low yield for unexpected germline variation and the large proportion of patients with VUS results, analysis and return of germline results should adhere to guidelines for secondary findings rather than diagnostic hereditary cancer testing. Clin Cancer Res; 22(16); 4087-94. ©2016 AACRSee related commentary by Mandelker, p. 3987.

Opportunities for immunotherapy in microsatellite instable colorectal cancer

Microsatellite instability (MSI), the somatic accumulation of length variations in repetitive DNA sequences called microsatellites, is frequently observed in both hereditary and sporadic colorectal cancer (CRC). It has been established that defects in the DNA mismatch repair (MMR) pathway underlie the development of MSI in CRC. After the inactivation of the DNA MMR pathway, misincorporations, insertions and deletions introduced by DNA polymerase slippage are not properly recognized and corrected. Specific genomic regions, including microsatellites, are more prone for DNA polymerase slippage and, therefore, more susceptible for the introduction of these mutations if the DNA MMR capacity is lost. Some of these susceptible genomic regions are located within the coding regions of genes. Insertions and deletions in these regions may alter their reading frame, potentially resulting in the transcription and translation of frameshift peptides with c-terminally altered amino acid sequences. These frameshift peptides are called neoantigens and are highly immunogenic, which explains the enhanced immunogenicity of MSI CRC. Neoantigens contribute to increased infiltration of tumor tissue with activated neoantigen-specific cytotoxic T lymphocytes, a hallmark of MSI tumors. Currently, neoantigen-based vaccination is being studied in a clinical trial for Lynch syndrome and in a trial for sporadic MSI CRC of advanced stage. In this Focussed Research Review, we summarize current knowledge on molecular mechanisms and address immunological features of tumors with MSI. Finally, we describe their implications for immunotherapeutic approaches and provide an outlook on next-generation immunotherapy involving neoantigens and combinatorial therapies in the setting of MSI CRC.