Advantage of HSP110 (T17) marker inclusion for microsatellite instability (MSI) detection in colorectal cancer patients

Immune-checkpoint gene expression and BCG response in non-muscle invasive bladder cancer

METHODS

One-hundred-six patients diagnosed with non-muscle invasive bladder cancer and treated with intravesical BCG were included and divided into two groups, BCG-responsive (n = 47) and -unresponsive (n = 59). Immunohistochemistry was used to evaluate PD-L1 expression and MSI was assessed by a commercial multiplex PCR kit. The mRNA expression profile of 15 immune checkpoints was performed using the nCounter technology. For in silico validation, two distinct cohorts sourced from the Gene Expression Omnibus (GEO) database were used.

RESULTS

Among the 106 patients, only one (<1 %) exhibited MSI instability. PD-L1 expression was present in 9.4 % of cases, and no association was found with BCG-responsive status. We found low gene expression of canonic actionable immune checkpoints PDCD1 (PD-1), CD274 (PD-L1), and CTLA4, while high expression was observed for CD276 (B7-H3), CD47, TNFRSF14, IDO1 and PVR (CD155) genes. High IDO1 expression levels was associated with worst overall survival. The PDCD1, CTLA4 and TNFRSF14 expression levels were associated with BCG responsiveness, whereas TIGIT and CD276 were associated with unresponsiveness. Finally, CD276 was validated in silico cohorts.

CONCLUSION

In NMIBC, MSI is rare and PD-L1 expression is present in a small subset of cases. Expression levels of PDCD1, CTLA4, TNFRSF14, TIGIT and CD276 could constitute predictive biomarkers of BCG responsiveness.

Overall Survival, BRAF, RAS, and MSI Status in Patients Who Underwent Cetuximab After Refractory Chemotherapy for Metastatic Colorectal Cancer

PURPOSE

Evaluate overall survival (OS), RAS, BRAF, and MSI frequencies in patients with metastatic colorectal cancer (mCRC), refractory to chemotherapy, and finally treated with cetuximab.

METHODS

A retrospective cohort study to evaluate 211 mCRC patients with wild-type KRAS treated with cetuximab. BRAF V600E, KRAS, NRAS gene mutations, and MSI status were identified using PCR techniques in a population of pre-treated patients who were refractory to fluoropyrimidines, oxaliplatin, and irinotecan. In addition, we evaluated the mutation frequency of the BRAF and NRAS genes and the MSI status of this population. Uni- and multivariate analyses were performed for independent prognostic factors of OS.

RESULTS

The median OS was 10.4 months, 6.6 months for patients with right and 11.5 months for left colon cancers (p = 0.02). The frequencies of mutations were BRAF at 3.9% (median OS of 4.9 months), NRAS at 3.38% (median OS of 6.9 months), and MSI-High status at 3.3% (median OS of 4.6 months). The OS, NRAS, and MSI frequencies were similar to those found in other studies that evaluated cetuximab in poly-treated patients and were associated with lower survival rates in univariate analyses. The frequency of BRAF mutations was lower than that found in previous studies. The only variable that remained significant for OS in the multivariate model was tumour laterality, with patients with right colon cancer presenting a worse prognosis (HR = 2.81).

CONCLUSION

Although BRAF, NRAS mutations, and MSI-High status were associated with shorter OS in univariate analyses, only tumour laterality remained an independent prognostic factor in the multivariate analysis.

Case report: Efficacy of immunotherapy as conversion therapy in dMMR/MSI-H colorectal cancer: a case series and review of the literature

Immunotherapy has demonstrated a role in the therapeutic landscape of a small subset of patients with colorectal carcinoma (CRC) that harbor a microsatellite instability (MSI-H) status due to a deficient DNA mismatch repair (dMMR) system. The remarkable responses to immune checkpoint inhibitors (ICIs) are now being tested in the neoadjuvant setting in localized CRC, where the dMMR/MSI-H status can be found in up to 15% of patients, with remarkable results obtained in NICHE2 and 3 trials, among others. This case series aims to report our experience at a tertiary center and provide a comprehensive analysis of the possible questions and challenges to overcome if ICIs were established as standard of care in a neoadjuvant setting, as well as the potential role they may have as conversion therapy not only in locoregional advanced CRC but also in oligometastatic disease.

Concordance in detection of microsatellite instability by PCR and NGS in routinely processed tumor specimens of several cancer types

BACKGROUND

Microsatellite instability (MSI) occurs in several cancer types and is commonly used for prognosis and as a predictive biomarker for immune checkpoint therapy.

METHODS

We analyzed n = 263 formalin-fixed paraffin-embedded (FFPE) tumor specimens (127 colorectal cancer (CRC), 55 endometrial cancer (EC), 33 stomach adenocarcinoma (STAD), and 48 solid tumor specimens of other tumor types) with a capillary electrophoresis based multiplex monomorphic marker MSI-PCR panel and an amplicon-based NGS assay for microsatellite instability (MSI+). In total, n = 103 (39.2%) cases with a known defect of the DNA mismatch repair system (dMMR), determined by a loss in protein expression of MSH2/MSH6 (n = 48, 46.6%) or MLH1/PMS2 (n = 55, 53.4%), were selected. Cases with an isolated loss of MSH6 or PMS2 were excluded.

RESULTS

The overall sensitivity and specificity of the NGS assay in comparison with the MSI-PCR were 92.2% and 98.8%. With CRC cases a nearly optimal concordance was reached (sensitivity 98.1% and specificity 100.0%). Whereas EC cases only show a sensitivity of 88.6% and a specificity of 95.2%, caused by several cases with instability in less than five monomorphic markers, which could be difficult to analyze by NGS (subtle MSI+ phenotype).

CONCLUSIONS

MSI analysis of FFPE DNA by NGS is feasible and the results show a high concordance in comparison with the monomorphic marker MSI-PCR. However, cases with a subtle MSI+ phenotype, most frequently manifest in EC, have a risk of a false-negative result by NGS and should be preferentially analyzed by capillary electrophoresis.

Discrepancy among microsatellite instability detection methodologies in non-colorectal cancer: Report of 3 cases

BACKGROUND

Microsatellite instability (MSI) is a predictive biomarker for cancer immunotherapy. The tumor-agnostic nature of MSI makes it a denominator for immunotherapy in several solid tumors. It can be assessed using next-generation sequencing (NGS), fluorescent multiplex PCR, and immunohistochemistry (IHC).

CASE SUMMARY

Here, we report 3 cases with discordant MSI results detected using different methods. A cholangiocellular carcinoma case revealed proficient mismatch repair (MMR) by IHC but high MSI (MSI-H) by liquid NGS. A cervical cancer case revealed deficient MMR by IHC, microsatellite stable by PCR, and MSI-H by NGS. Lastly, an endometrial cancer case revealed proficient MMR by IHC but MSI-H by NGS.

CONCLUSION

IHC for MMR status is the first choice due to several advantages. However, in cases of indeterminate IHC results, molecular testing by MSI-PCR is preferred. Recently, NGS-based MSI assays are being widely used to detect MSI-H tumors. All three methods have high accuracy; however, the inconsistencies between them may lead to misdiagnosis.

Microsatellite Status Detection of Colorectal Cancer: Evaluation of Inconsistency between PCR and IHC

Objective: An essential component of precision medical treatment for colorectal cancer (CRC) is the use of microsatellite state in combination with polymerase chain reaction (PCR) and immunohistochemistry (IHC) as the primary clinical detection methods. Microsatellite instability-high (MSI-H) or mismatch-repair deficiency (dMMR) accounts for about 15% of all CRC patients. Characterized by a high mutation burden, MSI-H is a predictive biomarker of immune checkpoint inhibitors (ICIs). Misdiagnosis of microsatellite status has been shown to be an important cause of resistance to immune checkpoint inhibitors. Therefore, a rapid and accurate assessment of microsatellite status can be beneficial for precision medicine in CRC. Methods: We evaluated the rate of discordance between PCR and IHC detection of microsatellite status from a cohort of patients that had 855 colorectal cancers. PCR-based microsatellite assay was performed using a set of five monomorphic mononucleotide makers (NR-24, BAT-25, CAT-25, BAT-26, MONO-27) and two polymorphic pentanucleotide (Penta D and Penta E). IHC was used to detect the absence of mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2). The inconsistency rates of the two assays were evaluated. Results: Among 855 patients,15.6% (134 to 855) cases were identified as MSI-H by PCR, whereas 16.9% (145 to 855) cases were identified as dMMR by IHC. There were 45 patients with discordant results between IHC and PCR. Of these, 17 patients were classified as MSI-H/pMMR and 28 patients as MSS/dMMR. When the clinicopathological characteristics of these 45 patients were compared to those of the 855 patients, it was found that more patients were younger than 65 years old (80% to 63%), more were male (73% to 62%), more were located in the right colon (49% to 32%), and more were poorly differentiated (20% to 15%). Conclusion: Our study demonstrated a high concordance between the PCR and IHC results. In order to reduce the ineffective treatment of ICIs due to MSI misdiagnosis, the patient's age, gender, tumor location and degree of differentiation should be included in the clinician's selection of MSI testing in colorectal cancer.

Genomic profile of two Brazilian choroid plexus tumors by whole-exome sequencing

Choroid plexus tumors (CPTs) are rare intracranial neoplasms, representing <1% of all brain tumors, yet they represent 20% of first-year pediatric brain tumors. Although these tumors have been linked to TP53 germline mutations in the context of Li-Fraumeni syndrome, their somatic driver alterations remain poorly understood. In this study, we report two cases of lateral ventricle tumors: 3-yr-old male diagnosed with an atypical choroid plexus papilloma (aCPP), and a 6-mo-old female diagnosed with a choroid plexus carcinoma (CPC). We performed whole-exome sequencing of paired blood and tumor tissue in both patients, categorized somatic variants, and determined copy-number alterations. Our analysis revealed a tier II variant (Association for Molecular Pathology [AMP] criteria) in BRD1, a H3 and TP53 acetylation agent, in the aCPP. In addition, we detected copy-number gains on Chromosomes 12, 18, and 20 and copy-number losses on Chromosomes 13q and 22q (BRD1 locus) in this tumor. The CPC tumor had only a pathogenic germline TP53 variant, based on American College of Medical Genetics (ACMG) criteria, with a clinical and familiar history of Li-Fraumeni syndrome. The CPC patient presented loss of heterozygosity (LoH) of TP53 loci and hyperdiploid genome. Both tumors were microsatellite-stable. This is the first study performing whole-exome sequencing in Brazilian choroid plexus tumors, and in line with the literature, we corroborate the absence of recurrent somatic mutations in these tumors. Further studies with larger sample sizes are necessary to confirm our findings and better understand the underlying biology of these tumors.

Microsatellite instability assessment is instrumental for Predictive, Preventive and Personalised Medicine: status quo and outlook

A form of genomic alteration called microsatellite instability (MSI) occurs in a class of tandem repeats (TRs) called microsatellites (MSs) or short tandem repeats (STRs) due to the failure of a post-replicative DNA mismatch repair (MMR) system. Traditionally, the strategies for determining MSI events have been low-throughput procedures that typically require assessment of tumours as well as healthy samples. On the other hand, recent large-scale pan-tumour studies have consistently highlighted the potential of massively parallel sequencing (MPS) on the MSI scale. As a result of recent innovations, minimally invasive methods show a high potential to be integrated into the clinical routine and delivery of adapted medical care to all patients. Along with advances in sequencing technologies and their ever-increasing cost-effectiveness, they may bring about a new era of Predictive, Preventive and Personalised Medicine (3PM). In this paper, we offered a comprehensive analysis of high-throughput strategies and computational tools for the calling and assessment of MSI events, including whole-genome, whole-exome and targeted sequencing approaches. We also discussed in detail the detection of MSI status by current MPS blood-based methods and we hypothesised how they may contribute to the shift from conventional medicine to predictive diagnosis, targeted prevention and personalised medical services. Increasing the efficacy of patient stratification based on MSI status is crucial for tailored decision-making. Contextually, this paper highlights drawbacks both at the technical level and those embedded deeper in cellular/molecular processes and future applications in routine clinical testing.

Digital expression profile of immune checkpoint genes in medulloblastomas identifies CD24 and CD276 as putative immunotherapy targets

Introduction

Medulloblastoma is the most common and lethal pediatric malignant brain tumor. It comprises four main molecular subgroups: WNT-activated, SHH-activated, Group 3, and Group 4. Medulloblastoma treatment is surgical resection, craniospinal radiation, and chemotherapy. However, many patients do not respond to therapy, and most suffer severe side effects. Cancer immunotherapy targeting immune checkpoints (IC) (PD-1, PD-L1, and CTLA4) has been getting disappointing outcomes in brain tumors. Nevertheless, other less explored immune checkpoints may be promising candidates for medulloblastoma therapy.

Objectives

In the present study, we aimed to characterize the expression profile of 19 immune checkpoints in medulloblastoma.

Methods

We analyzed 88 formalin-fixed paraffin-embedded medulloblastomas previously classified for each molecular subgroup and three non-tumoral brain tissue. mRNA levels of 19 immune checkpoint-related genes were quantified using the nCounter (PanCancer Immune Profiling Panel) assay. Further in silico analysis was performed in two larger public microarray datasets, one of which enabled comparisons between tumoral and non-tumoral tissues. Immunohistochemistry of PD-L1 was performed in a subset of cases. Microsatellite instability was also molecularly analyzed.

Results

We observed an absence of expression of the canonic ICs, namely PDCD1 (PD-1), CD274 (PD-L1), and CTLA4, as well as CD80, CD86, BTLA, IDO1, CD48, TNFSF14, CD160, CEACAM1, and CD244. PD-L1 protein expression was also practically absent. We found higher mRNA levels of CD24, CD47, CD276 (B7-H3), and PVR, and lower mRNA levels of HAVCR2, LAG3, and TIGIT genes, with significant differences across the four molecular subgroups. Compared to the non-tumor tissues, the expression levels of CD276 in all subgroups and CD24 in SHH, Group 3, and Group 4 subgroups are significantly higher. The in silico analysis confirmed the expression profile found in the Brazilian cohort, including the lower/absent expression of the canonic ICs. Moreover, it confirmed the overexpression of CD24 and CD276 in medulloblastomas compared with the non-tumor tissue. Additionally, CD276 and CD24 high levels were associated with worse survival.

Conclusion

These results highlight the low or absence of mRNA levels of the canonic targetable ICs in medulloblastomas. Importantly, the analysis revealed overexpression of CD24 and CD276, which can constitute prognostic biomarkers and attractive immunotherapy targets for medulloblastomas.

Cancer immune profiling unveils biomarkers, immunological pathways, and cell type score associated with glioblastoma patients' survival

Introduction

Glioblastoma (GBM), isocitrate dehydrogenase (IDH) wild-type (IDH ^wt), and grade 4 astrocytomas, IDH mutant (IDH ^mut), are the most common and aggressive primary malignant brain tumors in adults. A better understanding of the tumor immune microenvironment may provide new biomarkers and therapeutic opportunities.

Objectives

We aimed to evaluate the expression profile of 730 immuno-oncology-related genes in patients with IDH ^wt GBM and IDH ^mut tumors and identify prognostic biomarkers and a gene signature associated with patient survival.

Methods

RNA was isolated from formalin-fixed, paraffin-embedded sections of 99 tumor specimens from patients treated with standard therapy. Gene expression profile was assessed using the Pan-Cancer Immune Profiling Panel (Nanostring Technologies, Inc., Seattle, WA, USA). Data analysis was performed using nSolverSoftware and validated in The Cancer Genome Atlas. In addition, we developed a prognostic signature using the cox regression algorithm (Least Absolute Shrinkage and Selection Operator).

Results

We found 88 upregulated genes, high immunological functions, and a high macrophage score in IDH ^wt GBM compared to IDH ^mut tumors. Regarding IDH ^wt GBM, we found 24 upregulated genes in short-term survivors (STS) and overexpression of CD274 (programmed death-ligand 1, PD-L1). Immune pathways, CD45, cytotoxic, and macrophage scores were upregulated in STS. Two different prognostic groups were found based on the 12-gene signature (CXCL14, PSEN2, TNFRSF13C, IL13RA1, MAP2K1, TNFSF14, THY1, CTSL, ITGAE, CHUK, CD207, and IFITM1).

Conclusion

The elevated expression of immune-oncology-related genes was associated with worse outcome in IDH ^wt GBM patients. Increased immune functions, CD45, cytotoxic cells, and macrophage scores were associated with a more aggressive phenotype and may provide promising possibilities for therapy. Moreover, a 12 gene-based signature could predict patients' prognosis.

Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer

CONTEXT.—

The US Food and Drug Administration (FDA) approved immune checkpoint inhibitor therapy for patients with advanced solid tumors that have DNA mismatch repair defects or high levels of microsatellite instability; however, the FDA provided no guidance on which specific clinical assays should be used to determine mismatch repair status.

OBJECTIVE.—

To develop an evidence-based guideline to identify the optimal clinical laboratory test to identify defects in DNA mismatch repair in patients with solid tumor malignancies who are being considered for immune checkpoint inhibitor therapy.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Using the National Academy of Medicine-endorsed Grading of Recommendations Assessment, Development and Evaluation approach, the recommendations were derived from available evidence, strength of that evidence, open comment feedback, and expert panel consensus. Mismatch repair immunohistochemistry, microsatellite instability derived from both polymerase chain reaction and next-generation sequencing, and tumor mutation burden derived from large panel next-generation sequencing were within scope.

RESULTS.—

Six recommendations and 3 good practice statements were developed. More evidence and evidence of higher quality were identified for colorectal cancer and other cancers of the gastrointestinal (GI) tract than for cancers arising outside the GI tract.

CONCLUSIONS.—

An optimal assay depends on cancer type. For most cancer types outside of the GI tract and the endometrium, there was insufficient published evidence to recommend a specific clinical assay. Absent published evidence, immunohistochemistry is an acceptable approach readily available in most clinical laboratories.

Deficient mismatch repair/microsatellite unstable colorectal cancer: Diagnosis, prognosis and treatment

Microsatellite unstable (MSI) colorectal cancers (CRCs) are due to DNA mismatch repair (MMR) deficiency and occurs in15% of non-metastatic diseases and 5% in the metastatic setting. Nearly 30% of MSI CRCs occur in a context of constitutional mutation of the MMR system (Lynch syndrome). Others are sporadic cancers linked to a hypermethylation of the MLH-1 promoter. The pathogenic alterations of MMR genes lead to the accumulation of frequent somatic mutational events and these tumours arbour a high antigen burden and are highly infiltrated with cytotoxic T-cell lymphocytes. Microsatellite instability/DNA mismatch repair deficiency (MSI/dMMR) status has prognostic and predictive implications in non-metastatic and metastatic CRCs. The prognostic value of MSI status in non-metastatic CRCs has been studied extensively, yet the data are more limited for its predictive value in terms of adjuvant chemotherapy efficacy. In both cases (metastatic and non-metastatic settings) treatment with immune check-point inhibitors (ICIs) have shown a remarkable effectiveness in the context of MSI/dMMR status. Indeed, recent data from prospective cohorts and randomised trials have shown a dramatical improvement of survival with immunotherapy (programmed death-ligand 1 [PD-(L)1]   cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] blockage) in metastatic or non-metastatic MSI/dMMR CRC. In this review we report and discuss how and for whom to test for the MSI/dMMR phenotype, as well as the prognostic value of this phenotype and the new treatment recommendations options for this unique CRC population. Despite their efficacy, primary and secondary resistance to immune checkpoint inhibitors (ICIs) are observed in more than 50% MSI-H/dMMR CRC patients and in the future how to identify these patients and to overcome resistance will be an important challenge.

Microsatellite Instability: From the Implementation of the Detection to a Prognostic and Predictive Role in Cancers

Microsatellite instability (MSI) has been identified in several tumors arising from either germline or somatic aberration. The presence of MSI in cancer predicts the sensitivity to immune checkpoint inhibitors (ICIs), particularly PD1/PD-L1 inhibitors. To date, the predictive role of MSI is currently used in the selection of colorectal cancer patients for immunotherapy; moreover, the expansion of clinical trials into other cancer types may elucidate the predictive value of MSI for non-colorectal tumors. In clinical practice, several assays are used for MSI testing, including immunohistochemistry (IHC), polymerase chain reaction (PCR) and next-generation sequencing (NGS). In this review, we provide an overview of MSI in various cancer types, highlighting its potential predictive/prognostic role and the clinical trials performed. Finally, we focus on the comparison data between the different assays used to detect MSI in clinical practice.

Association of microsatellite instability (MSI) status with the 5-year outcome and genetic ancestry in a large Brazilian cohort of colorectal cancer

Colorectal cancer (CRC) has a high incidence and mortality worldwide. Microsatellite instability (MSI) is crucial in CRC, with distinct molecular and clinicopathological features in patients. Nowadays, it is a predictive marker for immunotherapy. We proposed to evaluate the 5-year outcome of MSI status in 1002 Brazilian CRC, and associate it with genetic ancestry, molecular and clinicopathological features. MSI evaluation was performed using molecular markers. MSI+ tumors were analyzed for alterations in 23 MSI-targeted genes. Genetic ancestry was evaluated using an Ancestry-Informative markers panel. MSI status was analyzed in relation to CRC specific survival and other clinical and genetic variables. MSI+ status was observed in 10.5% of cases. MSI+ status was significantly associated with the anatomic site right colon, mucinous histological type, clinical stage II, histological grade III/undifferentiated, no recurrence of disease, and live cases without cancer. No association of MSI status with genetic ancestry components was observed. MSI-targeted genes analyses showed the most frequently altered genes: ATM, EGFR, MRE11, ROCK1, and TGFBRII. There was a statistically significant difference in cancer-specific survival between cases according to MSI status. This study constitutes the most comprehensive analyses of the MSI impact on the Brazilian CRC. MSI+ frequency in Brazilian CRC agreed with the literature and was associated with several clinicopathological features related with less aggressive tumors, independently of their genetic ancestry.

Helicobacter pylori modulated host immunity in gastric cancer patients with S-1 adjuvant chemotherapy

BACKGROUND

Paradoxically, Helicobacter pylori-positive (HP+) advanced gastric cancer patients have a better prognosis than those who are HP-negative (HP-). Immunologic and statistical analyses can be used to verify whether systemic mechanisms modulated by HP are involved in this more favorable outcome.

METHODS

A total of 658 advanced gastric cancer patients who underwent gastrectomy were enrolled. HP infection, mismatch repair, programmed death-ligand 1 (PD-L1), and CD4/CD8 proteins, and microsatellite instability were analyzed. Overall survival (OS) and relapse free survival (RFS) rates were analyzed after stratifying clinicopathological factors. Cox proportional hazards regression analysis was performed to identify independent prognostic factors.

RESULTS

Among 491 cases that were analyzed, 175 (36%) and 316 (64%) cases were HP+ and HP⁻, respectively. Analysis of RFS indicated an interaction of HP status among the subgroups for S-1 dose (Pinteraction=0.0487) and PD-L1 (P = .016). HP+ patients in the PD-L1⁻ group had significantly higher five-year OS and RFS than HP- patients (81% vs. 68%; P = .0011; HR 0.477; 95% CI, 0.303-0.751 and 76% vs. 63% P = .0011; HR 0.508; 95% CI, 0.335-0.771, respectively). The five-year OS and RFS was also significantly higher for HP+ compared to HP- patients in the PD-L1-/S-1-reduced group (86% vs. 46%; P = .0014; HR 0.205; 95% CI, 0.07-0.602 and 83% vs. 34%; P = .001; HR 0.190; 95% CI, 0.072-0.498, respectively). Thus, HP status was identified as one of the most potentially important independent factors to predict prolonged survival.

CONCLUSION

This retrospective study suggests that an HP-modulated host immune system may contribute to prolonged survival in the absence of immune escape mechanisms of gastric cancer.

HSP110 as a Diagnostic but Not a Prognostic Biomarker in Colorectal Cancer With Microsatellite Instability

Determination of microsatellite instability (MSI) using molecular test and deficient mismatch repair (dMMR) using immunohistochemistry (IHC) has major implications on colorectal cancer (CRC) management. The HSP110 T₁₇ microsatellite has been reported to be more monomorphic than the common markers used for MSI determination. Large deletion of HSP110 T₁₇ has been associated with efficacy of adjuvant chemotherapy in dMMR/MSI CRCs. The aim of this study was to evaluate the interest of HSP110 deletion/expression as a diagnostic tool of dMMR/MSI CRCs and a predictive tool of adjuvant chemotherapy efficacy. All patients with MSI CRC classified by molecular testing were included in this multicenter prospective cohort (n = 381). IHC of the 4 MMR proteins was carried out. HSP110 expression was carried out by IHC (n = 343), and the size of HSP110 T₁₇ deletion was determined by PCR (n = 327). In the 293 MSI CRCs with both tests, a strong correlation was found between the expression of HSP110 protein and the size of HSP110 T₁₇ deletion. Only 5.8% of MSI CRCs had no HSP110 T₁₇ deletion (n = 19/327). HSP110 T₁₇ deletion helped to re-classify 4 of the 9 pMMR/MSI discordance cases as pMMR/MSS cases. We did not observe any correlation between HSP110 expression or HSP110 T₁₇ deletion size with time to recurrence in patients with stage II and III CRC, treated with or without adjuvant chemotherapy. HSP110 is neither a robust prognosis marker nor a predictor tool of adjuvant chemotherapy efficacy in dMMR/MSI CRC. However, HSP110 T₁₇ is an interesting marker, which may be combined with the other pentaplex markers to identify discordant cases between MMR IHC and MSI.

Accuracy and Clinical Relevance of Intra-Tumoral Fusobacterium nucleatum Detection in Formalin-Fixed Paraffin-Embedded (FFPE) Tissue by Droplet Digital PCR (ddPCR) in Colorectal Cancer

The use of droplet digital PCR (ddPCR) to identify and quantify low-abundance targets is a significant advantage for accurately detecting potentially oncogenic bacteria. Fusobacterium nucleatum (Fn) is implicated in colorectal cancer (CRC) tumorigenesis and is becoming an important prognostic biomarker. We evaluated the detection accuracy and clinical relevance of Fn DNA by ddPCR in a molecularly characterized, formalin-fixed, paraffin-embedded (FFPE) CRC cohort previously analyzed by qPCR for Fn levels. Following a ddPCR assay optimization and an analytical evaluation, Fn DNA were measured in 139 CRC FFPE cases. The measures of accuracy for Fn status compared to the prior results generated by qPCR and the association with clinicopathological and molecular patients’ features were also evaluated. The ddPCR-based Fn assay was sensitive and specific to positive controls. Fn DNA were detected in 20.1% of cases and further classified as Fn-high and Fn-low/negative, according to the median amount of Fn DNA that were detected in all cases and associated with the patient’s worst prognosis. There was a low agreement between the Fn status determined by ddPCR and qPCR (Cohen’s Kappa = 0.210). Our findings show that ddPCR can detect and quantify Fn in FFPE tumor tissues and highlights its clinical relevance in Fn detection in a routine CRC setting.

Microsatellite Instability Is Rare in the Admixed Brazilian Population of Non-Small Cell Lung Cancer: A Cohort of 526 Cases

BACKGROUND

Microsatellite instability (MSI) in non-small cell lung cancer (NSCLC) is uncommon; however, most studies refer to European and Asian populations. There are currently no data on MSI frequency in highly admixed populations, such as the one represented by Brazilian NSCLC patients.

AIM

This study aimed to evaluate the frequency of MSI in Brazilian NSCLC patients.

METHODS

We evaluated 526 patients diagnosed with NSCLC at the Barretos Cancer Hospital (Brazil). The molecular MSI evaluation was performed using a hexa-plex marker panel by polymerase chain reaction followed by fragment analysis. The mutation profile of MSI-positive cases was performed using next-generation sequencing.

RESULTS

Only 1 patient was MSI positive (0.19%). This patient was a female, white, and active smoker, and she was diagnosed with clinical stage IV lung adenocarcinoma at 75 years old. The molecular profile exhibited 4 Tumor Protein p53 (TP53) mutations and the absence of actionable mutations in the Epidermal Growth Factor Receptor (EGFR), Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), or V-Raf Murine Sarcoma Viral Oncogene Homolog B1 (BRAF) genes.

CONCLUSIONS

The frequency of MSI in Brazilian NSCLC patients is equally rare, a finding that is consistent with the current literature based on other populations such as Europeans, North Americans, and Asians.

A Simplified Protocol for Microsatellite Instability Evaluation in Iranian Patients at Risk for Lynch Syndrome

OBJECTIVE

The most important tumor characteristic of Lynch syndrome (LS) is microsatellite instability (MSI). In the current study, BAT34c4 and BAT26 mononucleotide markers were evaluated as part of efforts to test a cost-effective panel for MSI testing in Iranian patients, comparing it with the Promega kit.

METHODS

Amsterdam II clinical criteria were used to identify patients at risk for LS. The MSI status of these patients was determined using BAT34c4 and BAT26 markers, as well as the Promega kit. The results of both methods were compared, and the sensitivity and specificity of new short tandem repeat (STR) markers were estimated using statistical formulas.

RESULTS

Of the 37 patients we studied who were at risk for LS, 27% showed MSI-high results, via the Promega kit. The same results were achieved for BAT34c4 and BAT26 separately.

CONCLUSIONS

The novel 2-marker kit for MSI testing has similar accuracy as the Promega kit at a lower cost, due to fewer markers and a more economical labeling method.

A 4-Gene Signature Associated With Recurrence in Low- and Intermediate-Risk Endometrial Cancer

Background

The molecular profile of endometrial cancer has become an important tool in determining patient prognosis and their optimal adjuvant treatment. In addition to The Cancer Genome Atlas (TCGA), simpler tools have been developed, such as the Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE). We attempted to determine a genetic signature to build a recurrence risk score in patients diagnosed with low- and intermediate-risk endometrial cancer.

Methods

A case-control study was conducted. The eligible patients were women diagnosed with recurrence low- and intermediate-risk endometrial cancer between January 2009 and December 2014 at a single institution; the recurrence patients were matched to two nonrecurrence patients with the same diagnosis by age and surgical staging. Following RNA isolation of 51 cases, 17 recurrence and 34 nonrecurrence patients, the expression profile was determined using the nCounter^® PanCancer Pathways Panel, which contains 770 genes.

Results

The expression profile was successfully characterized in 49/51 (96.1%) cases. We identified 12 genes differentially expressed between the recurrence and nonrecurrence groups. The ROC curve for each gene was generated, and all had AUCs higher than 0.7. After backward stepwise logistic regression, four genes were highlighted: FN1, DUSP4, LEF1, and SMAD9. The recurrence risk score was calculated, leading to a ROC curve of the 4-gene model with an AUC of 0.93, sensitivity of 100%, and specificity of 72.7%.

Conclusion

We identified a four-gene signature that may be associated with recurrence in patients with low- and intermediate-risk endometrial cancer. This finding suggests a new prognostic factor in this poorly explored group of patients with endometrial cancer.

Methylation profile of colon cancer genes in colorectal precursor lesions and tumor tissue: perspectives for screening

AIMS

Epigenetic alterations of genes involved in colorectal carcinogenesis are likely to be informative biomarkers for early detection. We assessed the methylation profile of a panel of seven colon cancer-related genes comparing normal colon, colorectal cancer (CRC) precursor lesions and cancer tissues from a Brazilian cohort.

METHODS

The cohort comprised 114 CRC patients, including 40 matched normal tissue, 47 patients with adenomas, 33 with serrated polyps and 8 with normal colonic biopsy. DNA methylation status of SEPT9, ALX4, NDRG4, BMP3, APC, p16 and MLH1 was determined by pyrosequencing and correlated with clinicopathological features. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for all genes using cancer endpoint.

RESULTS

The most frequently methylated genes in cancer and in precancer lesions were SEPT9, ALX4, NDRG4, and BMP3, ranging from 55.3 to 95% of the samples. Overall, the frequency of methylation of these four genes in normal colonic tissue was significantly lower as compared to cancer or precursor lesions both in adenoma-carcinoma (p < .001 and p < .050) and serrated (sessile-serrated lesion) (p < .001 and p < .050) pathways. Additionally, sensitivity for the cancer endpoint ranged from 65.6 to 91.8%, and specificity from 17.9 to 62.9% for SEPT9, ALX4, NDRG4, and BMP3 genes. Moreover, the comethylation of ≥4 genes was higher in sessile-serrated lesion (87.5%) and conventional adenomas (78.7%) than in hyperplastic polyps (43.7%) (p = .025) and was significantly associated with proximal cancers (p = .042).

CONCLUSIONS

Our study suggests the DNA methylation can constitute potential biomarkers in CRC screening of Brazilian population.

Microsatellite Instability Analysis in Gastric Carcinomas of Moroccan Patients

Aim: To investigate correlations between microsatellite instability (MSI) and the phenotype, clinicopathological features, and overall survival (OS) in Moroccan gastric cancer (GC) patients. We evaluated the mutation frequency of 22 MSI-target genes in MSI-positive tumors. Materials and Methods: MSI evaluation were performed for 97 gastric tumors by multiplex polymerase chain reaction (PCR) using a panel of five quasimonomorphic mononucleotide repeat markers (NR27, NR21, NR24, BAT25, and BAT26). The mutation profiles of 22 MSI-target genes were assessed by multiplex PCR and genotyping. Kaplan-Meier curves, the log-rank test, and the Cox proportional hazard regression model were used to conduct survival analyses. Results: Microsatellite stable (MSS) status was observed in 77/97 (79.4%) gastric cancer samples, MSI-Low in 7 (7.2%) samples, and MSI-High (MSI-H) in 13 (13.4%) cases. The MSI-H phenotype was significantly associated with older age (p = 0.004), tumor location (p < 0.001), and intestinal-type of Lauren classification (p < 0.001). Among the 22 MSI target genes analyzed, the most frequently altered genes were HSP110 (84.6%), EGFR (30.8%), BRCA2 (23.1%), MRE11 (23.1%), and MSH3 (23.1%). Multivariate analysis revealed the MSS phenotype (Hazard ratio, 0.23; 95% confidence interval, 0.7-7.4; p = 0.014) as an independent indicator of poor prognosis in our population. Conclusions: This study is the first analysis of MSI in Moroccan GC patients. MSI-H GCs have distinct clinicopathological features and an improved OS. We have identified candidate target genes altered in MSI-positive tumors with potential clinical implications. These findings can guide immunotherapy designed for Moroccan GC patients.

Detection of Microsatellite Instability: State of the Art and Future Applications in Circulating Tumour DNA (ctDNA)

Simple Summary

Microsatellite instability (MSI) is a molecular fingerprint for defects in the mismatch repair system (dMMR) and is associated with higher risks of cancers. MSI/dMMR tumours are characterized by the accumulation of mutations throughout the genome, and particularly in microsatellite (MS) DNA repeat sequences. MSI stands as a major biomarker for familial cancer risk assessment, cancer prognosis, and therapeutic choices. Standard-of-care classification of MSI/dMMR tumours is most frequently achieved using immunohistochemistry or PCR-based assay directed against a set of five MS regions. However, novel molecular methods based on tumour tissue or plasma samples have been developed and could enter in the future trends of MSI testing. Here, we provide insights into these emerging approaches and discuss their advantages and limitations.

Abstract

Microsatellite instability (MSI) is a molecular scar resulting from a defective mismatch repair system (dMMR) and associated with various malignancies. MSI tumours are characterized by the accumulation of mutations throughout the genome and particularly clustered in highly repetitive microsatellite (MS) regions. MSI/dMMR status is routinely assessed in solid tumours for the initial screening of Lynch syndrome, the evaluation of cancer prognosis, and treatment decision-making. Currently, pentaplex PCR-based methods and MMR immunohistochemistry on tumour tissue samples are the standard diagnostic methods for MSI/dMMR. Other tissue methods such as next-generation sequencing or real-time PCR-based systems have emerged and represent viable alternatives to standard MSI testing in specific settings. The evolution of the standard molecular techniques has offered the opportunity to extend MSI determination to liquid biopsy based on the analysis of cell-free DNA (cfDNA) in plasma. This review aims at synthetizing the standard and emerging techniques used on tumour tissue samples for MSI/dMMR determination. We also provide insights into the MSI molecular techniques compatible with liquid biopsy and the potential clinical consequences for patients with solid cancers.

Clinicopathological and molecular characterization of Brazilian families at risk for Lynch syndrome

Lynch syndrome (LS), is the most common hereditary colorectal cancer syndrome. However, it is poorly characterized in Brazil. Therefore, we aimed to determine the spectrum of pathogenic variants in Mismatch Repair (MMR) genes and investigate the MLH1 promotor methylation role as a second hit in LS tumors. Tumor screening through microsatellite instability and immunohistochemistry for MMR proteins was performed in 323 cases who met clinical criteria. BRAF-V600E and MLH1 promoter methylation were analyzed for all MLH1-deficient tumors. Patients with MMR deficient tumor proceeded to germline genetic testing. MMR deficient tumors were detected in 41% of patients recruited. About half of patients carried a pathogenic germline variant. Two recurrent variants in MLH1 and three novel pathogenic variants were identified. Furthermore, pathogenic germline variants with concomitant somatic MLH1 hypermethylation were found in 6% of cases. Predictive genetic testing was offered to 387 relatives. Overall, 127 tumors were diagnosed in 100 LS patients, from 62 unrelated families. Our molecular data provide new information about the spectrum of MMR mutations, which contributes to a better characterization of LS in Brazil. Furthermore, we call attention to the possibility of failure in the diagnosis of germline MLH1 mutation carriers when somatic MLH1 hypermethylation is used to rule out LS.

Management of Non-Colorectal Digestive Cancers with Microsatellite Instability

Microsatellite instability (MSI) is a hallmark of genetic predisposition to DNA damage. It arises from either germline or somatic events leading to impaired function of the mismatch repair system. It can be detected via genetic sequencing or immunohistochemistry with relatively high concordance rates. The presence of MSI in a tumor reflects a high neoantigen load and predicts favorable treatment response to immune checkpoint inhibitors (ICIs). In gastrointestinal cancers, MSI is a predictive biomarker for ICIs with potential prognostic impact but its clinical utility varies widely depending on tumor type. This may be explained by the complexity of tumor microenvironment as highlighted by recent translational studies. In this review, we will discuss the predictive and prognostic value of MSI status in non-colorectal cancers of the digestive system, important clinical trials involving ICIs and potential strategies to overcome resistance to immunotherapy.

Pyknon-Containing Transcripts Are Downregulated in Colorectal Cancer Tumors, and Loss of PYK44 Is Associated With Worse Patient Outcome

Pyknons are specific human/primate-specific DNA motifs at least 16 nucleotides long that are repeated in blocks in intergenic and intronic regions of the genome and can be located in a new class of non-coding RNAs of variable length. Recent studies reported that pyknon deregulation could be involved in the carcinogenesis process, including colorectal cancer. We evaluated the expression profile of a set of 12 pyknons in a set of molecularly characterized colorectal cancer (CRC) patients. The pyknons (PYK10, PYK14, PYK17, PYK26, PYK27, PYK40, PYK41, PYK42, PYK43, PYK44, PYK83, and PYK90) expression was determined by qRT-PCR. A pilot analysis of 20 cases was performed, and consistent results were obtained for PYK10, PYK17, PYK42, PYK44, and PYK83. Further, the expression of the selected pyknons was evaluated in 73 CRC cases. Moreover, in 52 patients, we compared the expression profile in both tumor and normal tissues. All five pyknons analyzed showed significantly lower expression levels in the tumor compared to normal tissue. It was observed an association between expression of PYK10 with TP53 mutations (p = 0.029), PYK17 to histologic grade (p = 0.035), and PYK44 to clinical staging (p = 0.016). Moreover, levels of PYK44 were significantly associated with the patient's poor overall survival (p = 0.04). We reported the significant downregulation of pyknons motifs in tumor tissue compared with the normal counterpart, and the association of lower PYK44 expression with worse patient outcome. Further studies are needed to extend and validate these findings and determine the clinical-pathological impact.

Role of Genetic Ancestry in 1,002 Brazilian Colorectal Cancer Patients From Barretos Cancer Hospital

Background: Colorectal cancer (CRC) is the third most frequent and the second deadliest cancer worldwide. The ethnic structure of the population has been gaining prominence as a cancer player. The purpose of this study was to determine the genetic ancestry of Brazilian CRC patients. Moreover, we intended to interrogate its impact on patients' clinicopathological features.

Methods: Retrospective observational cohort study with 1,002 patients with CRC admitted from 2000 to 2014 at Barretos Cancer Hospital. Following tumor DNA isolation, genetic ancestry was assessed using a specific panel of 46 ancestry informative markers. Survival rates were obtained by the Kaplan–Meier method, and the log-rank test was used to compare the survival curves. Multivariable Cox proportional regression models were used to estimate hazard ratios (HRs).

Results: We observed considerable admixture in the genetic composition, with the following average proportions: European 74.2%, African 12.7%, Asian 6.5%, and Amerindian 6.6%. The multivariate analysis for cancer-specific survival showed that clinical stage, lymphovascular invasion, and the presence of recurrence were associated with an increased relative risk of death from cancer (p < 0.05). High African proportion was associated with younger age at diagnosis, while high Amerindian proportion was associated with the mucinous histological subtype.

Conclusions: This represents the larger assessment of genetic ancestry in a population of Brazilian patients with CRC. Brazilian CRC patients exhibited similar clinicopathological features as described in Western countries.

Impact: Genetic ancestry components corroborated the significant admixture, and importantly, patients with high African proportion develop cancer at a younger age.

Microsatellite instability and its associations with the clinicopathologic characteristics of diffuse large B-cell lymphoma

Microsatellite instability (MSI) has been investigated as a prognostic and predictive factor for chemotherapy in colorectal cancer and has recently been demonstrated to be predictive of the PD‐1/PD‐L1 checkpoint blockade response in various solid tumors. However, MSI status in diffuse large B‐cell lymphomas (DLBCLs) has not been thoroughly explored. This study investigated MSI status in DLBCLs and analyzed the associations between MSI and clinicopathologic characteristics and clinical outcomes. Ninety‐two cases of primary DLBCLs treated with R‐CHOP/CHOP chemotherapy between 2009 and 2017 were collected. MSI detection was performed by the Promega MSI Analysis System. The protein expression of MLH1, MSH2, MSH6, and PMS2 was detected by immunohistochemistry. The associations of MSI‐H and MSI‐L with progression‐free survival (PFS) and overall survival (OS) were assessed by COX models and Kaplan–Meier curves. The correlations of complete response (CR) after R‐CHOP/CHOP chemotherapy with MSI‐H and MSI‐L were examined by univariate and multivariate logistic regression analyses, respectively. 3 of 92 cases (3.2%) were high MSI (MSI‐H), and 9 cases (9/92, 9.8%) exhibited low MSI (MSI‐L). One case with MSI‐H showed negative expression of MSH2 and MSH6. Univariate analysis indicated that MSI‐L was correlated with poor response to R‐CHOP/CHOP chemotherapy in DLBCLs (OR, 0.178; 95% CI, 0.041‐0.776; P = .022). Multivariate analysis showed that MSI‐L was an independent predictive factor for non‐CR to R‐CHOP/CHOP chemotherapy (OR, 0.144; 95% CI, 0.027‐0.761; P = .023). Kaplan‐Meier curves showed that there was a trend that MSI‐H patients had favorable PFS (P = .36) and OS (P = .48), which did not have statistical significance and MSI‐L was not significantly correlated with PFS (P = .24) and OS (P = .52).Our study indicated that there existed MSI‐H and MSI‐L in DLBCLs. MSI‐L could be an independent predictive factor for the chemotherapy response in DLBCLs.

Microsatellite instability: a review of what the oncologist should know

The patients with high microsatellite instability (MSI-H)/mismatch repair deficient (dMMR) tumors recently have been reported that can benefit from immunotherapy, and MSI can be used as a genetic instability of a tumor detection index. However, many studies have shown that there are many heterogeneous phenomena in patients with MSI tumors in terms of immunotherapy, prognosis and chemotherapy sensitivity. Here we mainly review the research results of MSI detection methods, the mechanisms of MSI occurrence and its relationship with related tumors, aiming to make a brief analysis of the current research status of MSI and provide comparable reference and guidance value for further research in this field.

[Expressions of HSP110 family members in the testes and epididymis of mice at different stages of development and their regulation by hormones]

OBJECTIVE

To study the expressions of the members of HSP110 family in the testis and epididymis of mice at different stages of development and whether they are regulated by hormones.

METHODS

The testicular and epididymis tissues of mice at different ages (14, 21, 28, 35, 42, 49, 70, and 90 days after birth, 3 mice at each age) were collected for RT-PCR detection of the expression levels of HSP110 family members. Forty-eight mice were randomized into 3 groups for sham operation, castration, or castration with testosterone injections every other day (starting at 7 days after castration), and at 1, 3, 5, and 7 days after first testosterone injection, the expressions of HSP110 family in the epididymis were detected using RT-PCR.

RESULTS

The mRNA expression levels of HSP110 family members underwent obvious variations with the development of the mice: HSPA4, HSPA4l and HSPH1 expressions in the testicles of the mice first increased and then decreased, and gradually became stable; they also exhibited similar temporal patterns of changes in the epididymis. In the castrated mice, the mRNA expressions of HSPA4 and HSPA4l in the epididymis decreased significantly with the reduction of serum hormone levels (P &lt; 0.05), and became normal after the supplementation of exogenous hormone.

CONCLUSIONS

The expression levels of HSP110 family are affected by developmental regulation, and the expressions of HSPA4 and HSPA4l are under the regulation by hormones.

Mutation profiling of cancer drivers in Brazilian colorectal cancer

The molecular basis of colorectal cancer (CRC) can guide patient prognosis and therapy. In Brazil, knowledge on the CRC mutation landscape is limited. Here, we investigated the mutation profile of 150 cancer-related genes by next-generation sequencing and associated with microsatellite instability (MSI) and genetic ancestry in a series of 91 Brazilian CRC patients. Driver mutations were found in the APC (71.4%), TP53 (56.0%), KRAS (52.7%), PIK3CA (15.4%) and FBXW7 (10.9%) genes. Overall, genes in the MAPK/ERK, PIK3/AKT, NOTCH and receptor tyrosine kinase signaling pathways were mutated in 68.0%, 23.1%, 16.5%, and 15.3% of patients, respectively. MSI was found in 13.3% of tumors, most of which were proximal (52.4%, P< 0.001) and had a high mutation burden. European genetic ancestry was predominant (median of 83.1%), followed by Native American (4.1%), Asian (3.4%) and African (3.2%). NF1 and BRAF mutations were associated with African ancestry, while TP53 and PIK3CA mutations were inversely correlated with Native American ancestry. Our study suggests that Brazilian CRC patients exhibit a mutation profile similar to other populations and identify the most frequently mutated genes, which could be useful in future target therapies and molecular cancer screening strategies.

Mutational profile of Brazilian lung adenocarcinoma unveils association of EGFR mutations with high Asian ancestry and independent prognostic role of KRAS mutations

Lung cancer is the deadliest cancer worldwide. The mutational frequency of EGFR and KRAS genes in lung adenocarcinoma varies worldwide per ethnicity and smoking. The impact of EGFR and KRAS mutations in Brazilian lung cancer remains poorly explored. Thus, we investigated the frequency of EGFR and KRAS mutations in a large Brazilian series of lung adenocarcinoma together with patients’ genetic ancestry, clinicopathological and sociodemographic characteristics. The mutational frequency of EGFR was 22.7% and KRAS was 20.4%. The average ancestry proportions were 73.1% for EUR, 13.1% for AFR, 6.5% for AME and 7.3% for ASN. EGFR mutations were independently associated with never-smokers, high-Asian ancestry, and better performance status. KRAS mutations were independently associated with tobacco exposure and non-Asian ancestry. EGFR-exon 20 mutations were associated with worse outcome. The Cox regression model indicated a worse outcome for patients whose were older at diagnosis (>61 y), solid histological subtype, loss of weight (>10%), worse performance status (≥2), and presence of KRAS mutations and EGFR mutational status in TKi non-treated patients. In conclusion, we assessed the clinicopathological and ethnic impact of EGFR and KRAS mutations in the largest series reported of Brazilian lung adenocarcinomas. These findings can support future clinical strategies for Brazilian lung cancer patients.

MSI/MMR-deficient tumor diagnosis: Which standard for screening and for diagnosis? Diagnostic modalities for the colon and other sites: Differences between tumors

Microsatellite instability (MSI), which is caused by deficiency of the DNA mismatch repair (MMR) system, is the molecular abnormality observed in tumors associated with Lynch syndrome. Lynch syndrome represents one of the most frequent conditions of cancer predisposition in human, thus requiring specific care and genetic counseling. Moreover, research has recently focused increasingly on MMR deficiency due to its positive predictive value for the efficacy of immune checkpoints inhibitors (ICKi) in metastatic tumors, regardless of their primary origin. MSI has also been demonstrated to constitute an independent prognostic factor in several tumor types, being also associated with alternative response to chemotherapy. These observations have led many professional medical organizations to recommend universal screening of all newly diagnosed colorectal cancers for dMMR/MSI status and increasing evidence support the evaluation of MSI in all human tumors regardless of the cancer tissue of origin. Currently, two standard reference methods, namely immunohistochemistry and polymerase chain reaction, are recommended for the detection of dMMR/MSI status. These methods are equally valid as the initial screening test for dMMR/MSI in colorectal cancer. To date, there is no recommendation for the detection of dMMR/MSI in other primary tumors. In this review, we will present a comprehensive overview of the methods used for evaluation of tumor dMMR/MSI status in colorectal cancer, as well as in other tumor sites. We will see that the evaluation of this status remains challenging in some clinical settings, with the need to improve the above methods in these specific contexts.

Microbiota Profile and Impact of Fusobacterium nucleatum in Colorectal Cancer Patients of Barretos Cancer Hospital

Microbial diversity has been pointed out as a major factor in the development and progression of colorectal cancer (CRC). We sought to explore the richness and abundance of the microbial community of a series of colorectal tumor samples treated at Barretos Cancer Hospital, Brazil, through 16S rRNA sequencing. The presence and the impact of Fusobacterium nucleatum (Fn) DNA in CRC prognosis was further evaluated by qPCR in a series of 152 CRC cases. An enrichment for potentially oncogenic bacteria in CRC was observed, with Fusobacterium being the most abundant genus in the tumor tissue. In the validation dataset, Fn was detected in 35/152 (23.0%) of fresh-frozen tumor samples and in 6/57 (10.5%) of paired normal adjacent tissue, with higher levels in the tumor (p = 0.0033). Fn DNA in the tumor tissue was significantly associated with proximal tumors (p = 0.001), higher depth of invasion (p = 0.014), higher clinical stages (p = 0.033), poor differentiation (p = 0.011), MSI-positive status (p < 0.0001), BRAF mutated tumors (p < 0.0001), and the loss of expression of mismatch-repair proteins MLH1 (p < 0.0001), MSH2 (p = 0.003), and PMS2 (p < 0.0001). Moreover, the presence of Fn DNA in CRC tissue was also associated with a worse patient cancer-specific survival (69.9 vs. 82.2% in 5 years; p = 0.028) and overall survival (63.5 vs. 76.5%; p = 0.037). Here we report, for the first time, the association of F. nucleatum presence with important clinical and molecular features in a Brazilian cohort of CRC patients. Tumor detection and classification based on the gut microbiome might provide a promising approach to improve the prediction of patient outcome.

Relationship between Fusobacterium nucleatum, inflammatory mediators and microRNAs in colorectal carcinogenesis

AIM

To examine the effect of Fusobacterium nucleatum (F. nucleatum) on the microenvironment of colonic neoplasms and the expression of inflammatory mediators and microRNAs (miRNAs).

METHODS

Levels of F. nucleatum DNA, cytokine gene mRNA (TLR2, TLR4, NFKB1, TNF, IL1B, IL6 and IL8), and potentially interacting miRNAs (miR-21-3p, miR-22-3p, miR-28-5p, miR-34a-5p, miR-135b-5p) were measured by quantitative polymerase chain reaction (qPCR) TaqMan^® assays in DNA and/or RNA extracted from the disease and adjacent normal fresh tissues of 27 colorectal adenoma (CRA) and 43 colorectal cancer (CRC) patients. KRAS mutations were detected by direct sequencing and microsatellite instability (MSI) status by multiplex PCR. Cytoscape v3.1.1 was used to construct the postulated miRNA:mRNA interaction network.

RESULTS

Overabundance of F. nucleatum in neoplastic tissue compared to matched normal tissue was detected in CRA (51.8%) and more markedly in CRC (72.1%). We observed significantly greater expression of TLR4, IL1B, IL8, and miR-135b in CRA lesions and TLR2, IL1B, IL6, IL8, miR-34a and miR-135b in CRC tumours compared to their respective normal tissues. Only two transcripts for miR-22 and miR-28 were exclusively downregulated in CRC tumour samples. The mRNA expression of IL1B, IL6, IL8 and miR-22 was positively correlated with F. nucleatum quantification in CRC tumours. The mRNA expression of miR-135b and TNF was inversely correlated. The miRNA:mRNA interaction network suggested that the upregulation of miR-34a in CRC proceeds via a TLR2/TLR4-dependent response to F. nucleatum. Finally, KRAS mutations were more frequently observed in CRC samples infected with F. nucleatum and were associated with greater expression of miR-21 in CRA, while IL8 was upregulated in MSI-high CRC.

CONCLUSION

Our findings indicate that F. nucleatum is a risk factor for CRC by increasing the expression of inflammatory mediators through a possible miRNA-mediated activation of TLR2/TLR4.