Meta-analysis of microsatellite instability in relation to clinicopathological characteristics and overall survival in gastric cancer

Adjuvant Chemotherapy for Gastric Cancer Patients with Mismatch Repair Deficiency or Microsatellite Instability: Systematic Review and Meta-Analysis

BACKGROUND

Mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H) status serves as a predictor of a poor response to adjuvant chemotherapy among stage 2 colon cancer patients. This study aimed to investigate the efficacy of adjuvant chemotherapy in dMMR/MSI-H gastric cancer (GC).

METHODS

Clinical studies comparing adjuvant chemotherapy and surgery alone in dMMR/MSI-H GCs through June 2021 were retrieved to assess the survival of patients managed with both treatments. Two approaches were used to pool the hazard ratio (HR) of survival: (1) if Kaplan-Meier curves and number of patients at risk were provided, individual patient data were extracted. Cox models were used to calculate the HR with its 95% confidence interval (CI); (2) for study-level data, pooled HR was estimated using fixed/random-effects models.

RESULTS

Seven clinical studies were assessed. For dMMR/MSI-H versus mismatch repair-proficient (pMMR)/microsatellite stable (MSS)/microsatellite instability-low (MSI-L) status, the estimated 5-year disease-free survival (DFS) rate was 74.2% versus 51.5% (HR, 0.44; 95% CI, 0.32-0.62; P < 0.001) and the estimated 5-year OS rate was 60.5% versus 49.1% (HR, 0.71; 95% CI, 0.60-0.85; P < 0.001). The study-level data showed pooled HRs of 0.42 for DFS (95% CI, 0.31-0.57; P < 0.001) and 0.65 for OS (95% CI, 0.38-1.11; P = 0.114). For adjuvant chemotherapy versus observation of dMMR/MSI-H, the estimated 5-year DFS rate was 76.1% versus 73.3% (HR, 0.72; 95% CI, 0.45-1.15; P = 0.171) and the estimated 5-year OS rate was 73.5% versus 59.7% (HR, 0.62; 95% CI, 0.46-0.83; P = 0.001). Significant survival differences also were observed at study level.

CONCLUSIONS

The study findings confirm the benefit of adjuvant chemotherapy for dMMR/MSI-H GC patients.

Immunotherapy for gastric cancer: a 2021 update

Gastric cancer, the fifth most frequent cancer and the fourth leading cause of cancer deaths, accounts for a devastating death rate worldwide. Since the majority of patients with gastric cancer are diagnosed at advanced stages, they are not suitable for surgery and present with locally advanced or metastatic disease. Recent advances in immunotherapy have elicited a considerable amount of attention as viable therapeutic options for several cancer types. This work presents a summary of the currently ongoing clinical trials and critically addresses the efficacy of a large spectrum of immunotherapy approaches in the general population for gastric cancer as well as in relation to tumor genetic profiling.

Advanced oesophago-gastric adenocarcinoma in older patients in the era of immunotherapy. A review of the literature

Gastric (G) and gastro-esophageal junction (GEJ) adenocarcinomas are of the most common and deadly cancers worldwide and affect mainly patients over 70 years at diagnosis. Older age has been associated in gastric cancers with distal tumour location, well-differentiated adenocarcinoma and microsatellite instability and is not identified itself as an independent prognostic factor. As immune checkpoint inhibitors recently changed the landmark of advanced G and GEJ adenocarcinomas treatment, we decided to perform a literature review to define the evidence-level of clinical data in older patients. This work underlined the lasting low -inclusion rate of older patients and -implementation rate of frailty screening tools in clinical trials in G/GEJ carcinomas. In the first-line metastatic setting, two prospective randomized phase III studies have specifically assessed the efficacy of chemotherapy in older patients with HER2-negative gastric cancers, demonstrating the feasibility of reduced dose oxaliplatin-based chemotherapy regimen in this population. Only few data are available in HER2-positive tumors, or in the second-line setting. Furthermore, no specific trial with immune checkpoint inhibitors was performed in older frail patients whereas their benefit/adverse events ratio make them attractive candidates in this patient's population. We conclude that older fit patients can be treated in the same way as younger ones and included in clinical trials. Improving the outcome of older frail patients should be the oncology community next focus by implementing targeted interventions before initiating cancer therapy and designing specific clinical trials. Frailty screening tools and geriatric data collection have to be implemented in routine-practice and clinical trials.

Prognostic and predictive value of mismatch repair deficiency in gastric and gastroesophageal junction adenocarcinoma patients receiving neoadjuvant or adjuvant chemotherapy

BACKGROUND AND OBJECTIVES

Evidence is inconclusive regarding the prognostic significance of deficient DNA mismatch repair (dMMR) in gastric and gastroesophageal junction (GEJ) adenocarcinoma patients receiving chemotherapy. We aim to explore such associations with a large cohort.

METHODS

We retrospectively identified a consecutive cohort of patients who had histology proven gastric or GEJ adenocarcinoma and received neoadjuvant chemotherapy plus surgery or upfront surgery plus adjuvant chemotherapy. MMR status was assessed by immunohistochemistry staining on surgical specimen. The association of MMR status with tumor regression grade (TRG), overall survival (OS), and disease-free survival (DFS) were analyzed.

RESULTS

In total, 1568 patients received neoadjuvant or adjuvant chemotherapy, of which 128 (8.2%) had dMMR tumors. No significant difference was found in the frequencies of TRG categories between proficient MMR (pMMR) and dMMR tumors (p = .62). Among patients receiving neoadjuvant chemotherapy, dMMR status was associated with better OS (log-rank p = .044) and DFS (log-rank p = .022) in the univariate analysis; this association became nonsignificant after adjusting for pathologic stages and other prognostic factors. Similar results were found for patients receiving adjuvant chemotherapy.

CONCLUSIONS

dMMR status was not significantly associated with OS and DFS among gastric and GEJ adenocarcinoma patients with neoadjuvant and adjuvant platinum and fluorouracil-based chemotherapy.

Genomic and Transcriptomic Characteristics of Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) is a deadly disease with limited options for targeted therapy. With the help of next-generation sequencing studies over the last decade, we gained an understanding of the genomic architecture of EAC. The tumor suppressor gene TP53 is mutated in 70 to 80% of tumors followed by genomic alterations in CDKN2A, KRAS, ERBB2, ARID1A, SMAD4 and a long tail of less frequently mutated genes. EAC is characterized by a high burden of point mutations and genomic rearrangements, resulting in amplifications and deletions of genomic regions. The genomic complexity is likely hampering the efficacy of targeted therapies. Barrett's esophagus (BE), a metaplastic response of the esophagus to gastro-esophageal reflux disease, is the main risk factor for the development of EAC. Almost all EACs are derived from BE. The sequence from BE to EAC provides an opportunity to study the genomic evolution towards EAC. While the overlap of point mutations between BE and EAC within the same patient is, at times, surprisingly low, there is a correlation between the complexity of the genomic copy number profile and the development of EAC. Transcriptomic analyses separated EAC into a basal and a classical subtype, with the basal subtype showing a higher level of resistance to chemotherapy. In this review, we provide an overview of the current knowledge of the genomic and transcriptomic characteristics of EAC and their relevance for the development of the disease and patient care.

Gastric cancer molecular classification based on immunohistochemistry and in situ hybridization: Analysis in western patients after curative-intent surgery

BACKGROUND

Gastric cancer (GC) is a highly heterogeneous disease, and the identification of molecular subtyping of gastric adenocarcinoma emerged as a promising option to define therapeutic strategies and prognostic subgroups. However, the costs and technical complexity of molecular methodologies remains an obstacle to its adoption, and their clinical significance by other approaches needs further evidence.

AIM

To evaluate the clinicopathological characteristics and long-term survival of GC based on the subgroups of molecular classification by immunohistochemistry (IHC) and in situ hybridization (ISH).

METHODS

We retrospectively evaluated all patients who underwent D2-gastrectomy between 2009 and 2016 in a Western cohort of GC patients treated with curative intent. Microsatellite instability (MSI) status, E-cadherin, and p53 expression were analyzed by IHC, and Epstein-Barr virus (EBV) by ISH. Tissue microarrays were constructed for analysis. Clinicopathological characteristics and survival of GC were evaluated according to subtypes defined by The Cancer Genome Atlas (TCGA) Research Network Group and Asian Cancer Research Group (ACRG) classification systems.

RESULTS

A total of 287 GC patients were included. Based on IHC and ISH analysis, five profiles were defined as follows: E-cadherin aberrant (9.1%), MSI (20.9%), p53 aberrant (36.6%), EBV positivity (10.5%), and p53 normal (31%), which corresponded to tumors that showed no alteration in another profile. A flowchart according to the TCGA and ACRG classifications were used to define the subtypes, where clinical and pathological characteristics associated with GC subtypes were evidenced. Proximal location (P < 0.001), total gastrectomy (P = 0.001), and intense inflammatory infiltrate (P < 0.001) were characteristics related to EBV subtype. MSI subtype was predominantly associated with advanced age (P = 0.017) and the presence of comorbidities (P = 0.011). While Laurén diffuse type (P < 0.001) and advanced stage (P = 0.029) were related to genomically stable (GS) subtype. GS tumors and microsatellite stable/epithelial to mesenchymal transition phenotype subtype had worse disease-free survival (DFS) and overall survival (OS) than other subtypes. Conversely, MSI subtype of GC had better survival in both classifications. Type of gastrectomy, pT and the TCGA subtypes were independent factors associated to DFS and OS.

CONCLUSION

The IHC/ISH analysis was able to distinguish immunophenotypic groups of GC with distinct characteristics and prognosis, resembling the subtypes of the molecular classifications. Accordingly, this method of classification may represent a viable option for use in a clinical setting.

Current status and future potential of predictive biomarkers for immune checkpoint inhibitors in gastric cancer

Immunotherapy is revolutionising cancer treatment and has already emerged as standard treatment for patients with recurrent or metastatic gastric cancer (GC). Recent research has been focused on identifying robust predictive biomarkers for GC treated with immune checkpoint inhibitors (ICIs). The expression of programmed cell death protein-ligand-1 (PD-L1) is considered a manifestation of immune response evasion, and several studies have already reported the potential of PD-L1 expression as a predictive parameter for various human malignancies. Meanwhile, based on comprehensive molecular characterisation of GC, testing for Epstein-Barr virus and microsatellite instability is a potential predictive biomarker. Culminating evidence suggests that novel biomarkers, such as the tumour mutational burden and gene expression signature, could indicate the success of treatment with ICIs. However, the exact roles of these biomarkers in GC treated with ICIs remain unclear. Therefore, this study reviews recent scientific data on current and emerging biomarkers for ICIs in GC, which have potential to improve treatment outcomes.

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.

The value of restaging CT following neoadjuvant chemotherapy for resectable gastric cancer. A population-based study

Background

Response evaluation following neoadjuvant chemotherapy (NAC) in gastric cancer is debated. The aim of this study was to investigate the value of UICC-downstaging as mode of response evaluation following a MAGIC-style regimen of NAC.

Methods

Retrospective, population-based study on consecutive patients with resectable gastric adenocarcinoma receiving NAC from 2007 to 2016. CT-scan was obtained at diagnosis (rTNM) and repeated following NAC (yrTNM) to evaluate response in terms of downstaging. Further, yrTNM stage was crosstabulated to pathologic stage (ypTNM) to depict correlation between radiologic and pathologic assessment.

Results

Of 171 patients receiving NAC, 169 were available for response evaluation. For TNM-stages, 43% responded, 50% had stable disease and 7% progressed at CT. Crosstabulating yrTNM stage to ypTNM stage, 24% had concordant stages, with CT overstaging 38% and understaging 38% of the tumours, Cohen kappa ƙ = 0,06 (95%CI 0.004–0.12). Similar patterns of discordance were found for T-stages and N-stages separately. For M-category, restaging CT detected 12 patients with carcinomatosis, with an additional 14 diagnosed with carcinomatosis only at operation. No patient developed parenchymal or extra abdominal metastases, and none developed locally non-resectable tumour during delivery of NAC. Restaging CT with response evaluation was not able to stratify patients into groups of different long-term survival rates based on response mode.

Conclusions

Routine CT-scan following NAC is of limited value. Accuracy of CT staging compared to final pathologic stage is poor, and radiologic downstaging as measure of response evaluation is unreliable and unable to discriminate long-term survival rates based on response mode.

Prevalence and prognosis of microsatellite instability in oesogastric adenocarcinoma, NORDICAP 16-01

BACKGROUND

The prevalence and prognosis association of microsatellite instability (MSI) in oesogastric junction and gastric adenocarcinoma (OGC) have been reported with conflicting results.

METHODS

Patients with OGC from 2010 to 2015 were enrolled in this retrospective multicenter study. MSI was determined by genotyping. MLH1 promoter methylation and BRAFV600E mutation were screened in the MSI tumors.

RESULTS

Among 315 tumors analyzed, 39 (12.4%) were of the MSI phenotype. Compared to MSS tumors, MSI tumors were more frequent in patients >70 years (17% vs 9%, p=0.048) and in gastric antral primary (20% versus 5% in junction tumor and 12% in fundus tumor. Among 29 MSI tumors analyzed, 28 had a loss of MLH1 protein expression and 27 had MLH1 promotor hypermethylation. None had a BRAF V600E mutation. The 4-year cumulative incidence of recurrence for patients with resected tumor was significantly lower in dMMR tumors versus pMMR tumors (17% versus 47%, p=0.01). For the patients with unresectable tumor the median overall survival was 11 months in MSS group and 14 months in MSI group (p=0.24).

CONCLUSION

MSI prevalence in OGC was 12.4%, associated with antral localization and advanced age. Patients with MSI tumors had a lower cumulative incidence of recurrence after surgery. MSI phenotype was mainly associated with loss of MLH1 protein expression, MLH1 promotor hypermethylation and had no BRAFV600E mutation.

Association of histological subtype with risk of recurrence in craniopharyngioma patients: a systematic review and meta-analysis

It is controversial whether there is a different risk of recurrence between two histological subtypes in craniopharyngioma (CP) patients. Some reported that adamantinomatous craniopharyngioma (ACP) had a higher risk of recurrence than papillary craniopharyngioma (PCP), but others reported that there is no significant difference between them. So, we conducted this systematic review and meta-analysis to determine the association between the histological subtype of CP and the rate of recurrence. A comprehensive literature search was undertaken in PubMed, EMBASE, and Web of Science for all English articles published up to November 2020. Recurrence data stratified by ACP and PCP were extracted from studies meeting inclusion criteria. A pooled analysis of the association between the histological subtype of craniopharyngioma and rates of recurrence was performed. Thirteen articles containing 974 patients were included. When stratified by two pathological subtypes, the total recurrence rate of ACP was 26.0% and PCP was 14.1%, which showed ACP associated with a higher risk of tumor recurrence than PCP (odds ratio [OR] = 2.12, 95% confidence interval [CI] = 1.36, 3.30, P = 0.00). This is the first meta-analysis focusing on histological subtypes of CP. PCP associates with a lower risk of recurrence than ACP, indicating that ACP could act as one of recurrence risk factors for CP patients. Nevertheless, large sample size and well-designed multicenter studies in which the other clinical variables are controlled to determine the histological subtype of CP as an independent recurrence risk factor are needed.

Comprehensive analysis of DNA mismatch repair-deficient gastric cancer in a Japanese hospital-based population

BACKGROUND

The attention on mismatch repair-deficient (dMMR) gastric cancer has increased in this era of anti-PD-1 blockade therapy; however, the prevalence and molecular genetics of patients with dMMR gastric cancer have not been completely investigated.

METHODS

Immunohistochemistry of MMR proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary gastric cancers of 513 consecutive patients. Genetic and/or epigenetic alterations of the MMR genes were also investigated.

RESULTS

Loss of expression of one or more MMR proteins was observed in 58 patients (11.3%); 54 patients showed loss of MLH1/PMS2, 3 patients showed loss of MLH1/PMS2/MSH6 and 1 patient showed loss of PMS2 alone. Among these 58 patients, 55 showed hypermethylation of the promoter region of MLH1. Genetic testing revealed that the remaining three patients had Lynch syndrome (n = 1) or Lynch-like syndrome (n = 2). A total of 15 patients (25.9% of all patients with dMMR gastric cancer and 2.9% of all patients with gastric cancer), including 11 patients with stage I-III dMMR gastric cancer who had recurrence and 4 patients with stage IV dMMR gastric cancer, are potential candidates for the use of anti-PD-1 blockades.

CONCLUSIONS

This is the first study to investigate the frequency and molecular genetic mechanisms of dMMR gastric cancer comprehensively, focusing on the benefit of using PD-1 blockades. Our observations will be beneficial in the clinical practice of metastatic gastric cancer.

Characterization and clinical evaluation of microsatellite instability and loss of heterozygosity in tumor-related genes in gastric cancer

Microsatellite instability (MSI) detection is widely used in the diagnosis and prognosis evaluation of colorectal cancer. However, for gastric cancer (GC), there is no standard panel of microsatellites (MSs) used in clinical guidance. The present study aimed to identify useful predictors of the clinical features and for the prognosis of GC, based on an investigation of MSI and loss of heterozygosity (LOH) in tumor-related genes. First, from 20 tumor-related genes which were proven to be important to the development of GC, 91 MSs were identified, and PCR amplification, short tandem repeat scanning analysis and TA clone sequencing were used to analyze MSI and LOH in the first set of 90 GC samples. Subsequently, the same method was used to detect the MSI/LOH of the optimized loci in the second set of 136 GC samples. MSI/LOH in the mismatch repair genes was highly consistent with that in oncogenes and tumor suppressor genes, respectively. The length of the core sequence was a main factor for the MSI/LOH rate. The MSI of 12 single loci was significantly associated with lymph node metastasis. The MSI in TP53-1 and the LOH in MGMT-10 were significantly associated with early stages of tumor infiltration depth. The LOH in MGMT-10, PTN-2 and MCC-17 was significantly associated with TNM stage. The LOH in TP53-1 and ERBB2-12 was associated with adenocarcinoma. The MSI/LOH in 6 single loci of 5 tumor-related genes was associated with poor prognosis of GC. The present study demonstrated that the MSI/LOH of loci in tumor-associated genes was associated with 4 clinicopathological characteristics and outcomes of GC. These results may provide potential specific biomarkers for the clinical prediction and treatment of GC.

Is there still a place for conventional histopathology in the age of molecular medicine? Laurén classification, inflammatory infiltration and other current topics in gastric cancer diagnosis and prognosis

Gastric cancer (GC) is the fifth most common cancer and the third cause of cancer-related deaths worldwide. In western countries, more than half of GC patients are diagnosed at advanced stages and 5-year survival rates range between 20-30%. The only curative treatment is surgery, and despite recent advances in oncological therapies, GC prognosis is still poor. The main prognostic tool for patient categorization and treatment selection is the TNM classification, but its limitations are being increasingly recognized. Early recurrences may occur in early-stage disease, and patients at the same stage show heterogeneous outcomes. Thus, there is a need to improve GC stratification and to identify new prognostic factors, which may allow us to select drug-susceptible populations, refine patient grouping for clinical trials and discover new therapeutic targets. Molecular classifications have been developed, but they have not been translated to the clinical practice. On the other hand, histological assessment is cheap and widely available, and it is still a mainstay in the era of molecular medicine. Furthermore, histological features are acquiring new roles as reflectors of the genotype-phenotype correlation, and their potential impact on patient management is currently being analyzed. The aim of this literature review is to provide a modern overview of the histological assessment of GC. In this study, we discuss recent topics on the histological diagnosis of GC, focusing on the current role of Laurén classification and the potential value of new histological features in GC, such as inflammatory infiltration and tumor budding.

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2019

The annual Eastern Canadian Gastrointestinal Cancer Consensus Conference 2019 was held in Morell, Prince Edward Island, 19-21 September 2019. Experts in medical oncology, radiation oncology, and surgical oncology who are involved in the management of patients with gastrointestinal malignancies participated in presentations and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses multiple topics in the management of anal, colorectal, biliary tract, and gastric cancers, including: radiotherapy and systemic therapy for localized and advanced anal cancer; watch and wait strategy for the management of rectal cancer; role of testing for dihydropyrimidine dehydrogenase (DPD) deficiency prior to commencement of fluoropyrimidine therapy; radiotherapy and systemic therapy in the adjuvant and unresectable settings for biliary tract cancer; and radiotherapy and systemic therapy in the perioperative setting for early-stage gastric cancer.

Her2-Positive and Microsatellite Instability Status in Gastric Cancer-Clinicopathological Implications

Gastric cancer (GC) is one of the leading causes of cancer-related death. The combination of new molecular classifications with clinicopathological data could contribute to the individualization of patients and to the development of new therapeutic strategies. We examined the various associations in two molecular types of GC: HER2-positive (human epidermal growth factor receptor 2) and microsatellite instability (MSI), assessing their influence on treatment and prognosis. A retrospective study of 142 GC patients was performed with molecular characterization through HER2 overexpression and DNA repair protein expression for MSI. The percentage of HER2-positive tumors was 13.4%, predominantly in men. Correlations were found with intestinal type, metastases, advanced stages and chemotherapy. Almost 75% of HER2-positive patients died. MSI occurred in 16.2%, associated with advanced age, female sex, distal location and intestinal type. These patients had few metastases and low stages. The percentage of deaths was higher among MSI patients who received perioperative chemotherapy. The determination of HER2 and MSI status in GC is important for their association with specific clinicopathological features and for their prognostic and predictive value.

The Emerging Role of Liquid Biopsy in Gastric Cancer

(1) Background: Liquid biopsy (LB) is a novel diagnostic method with the potential of revolutionizing the prevention, diagnosis, and treatment of several solid tumors. The present paper aims to summarize the current knowledge and explore future possibilities of LB in the management of metastatic gastric cancer. (2) Methods: This narrative review examined the most recent literature on the use of LB-based techniques in metastatic gastric cancer and the current LB-related clinical trial landscape. (3) Results: In gastric cancer, the detection of circulating cancer cells (CTCs) has been recognized to have a prognostic role in all the disease stages. In the setting of localized disease, cell-free DNA (cfDNA) and circulating tumor DNA (ctDNA) qualitative and quantitative detection have the potential to inform on the risk of cancer recurrence and metastatic dissemination. In addition, gastric cancer-released exosomes may play an essential part in metastasis formation. In the metastatic setting, the levels of cfDNA show a positive correlation with tumor burden. There is evidence that circulating tumor microemboli (CTM) in the blood of metastatic patients is an independent prognostic factor for shorter overall survival. Gastric cancer-derived exosomal microRNAs or clonal mutations and copy number variations detectable in ctDNA may contribute resistance to chemotherapy or targeted therapies, respectively. There is conflicting and limited data on CTC-based PD-L1 verification and cfDNA-based Epstein-Barr virus detection to predict or monitor immunotherapy responses. (4) Conclusions: Although preliminary studies analyzing LBs in patients with advanced gastric cancer appear promising, more research is required to obtain better insights into the molecular mechanisms underlying resistance to systemic therapies. Moreover, validation and standardization of LB methods are crucial before introducing them in clinical practice. The feasibility of repeatable, minimally invasive sampling opens up the possibility of selecting or dynamically changing therapies based on prognostic risk or predictive biomarkers, such as resistance markers. Research is warranted to exploit a possible transforming area of cancer care.

Interrogation of gender disparity uncovers androgen receptor as the transcriptional activator for oncogenic miR-125b in gastric cancer

There is a male preponderance in gastric cancer (GC), which suggests a role of androgen and androgen receptor (AR). However, the mechanism of AR signaling in GC especially in female patients remains obscure. We sought to identify the AR signaling pathway that might be related to prognosis and examine the potential clinical utility of the AR antagonist for treatment. Deep learning and gene set enrichment analysis was used to identify potential critical factors associated with gender bias in GC (n = 1390). Gene expression profile analysis was performed to screen differentially expressed genes associated with AR expression in the Tianjin discovery set (n = 90) and TCGA validation set (n = 341). Predictors of survival were identified via lasso regression analyses and validated in the expanded Tianjin cohort (n = 373). In vitro and in vivo experiments were established to determine the drug effect. The GC gender bias was attributable to sex chromosome abnormalities and AR signaling dysregulation. The candidates for AR-related gene sets were screened, and AR combined with miR-125b was associated with poor prognosis, particularly among female patients. AR was confirmed to directly regulate miR-125b expression. AR-miR-125b signaling pathway inhibited apoptosis and promoted proliferation. AR antagonist, bicalutamide, exerted anti-tumor activities and induced apoptosis both in vitro and in vivo, using GC cell lines and female patient-derived xenograft (PDX) model. We have shed light on gender differences by revealing a hormone-regulated oncogenic signaling pathway in GC. Our preclinical studies suggest that AR is a potential therapeutic target for this deadly cancer type, especially in female patients.

How to Best Exploit Immunotherapeutics in Advanced Gastric Cancer: Between Biomarkers and Novel Cell-Based Approaches

Despite extensive research efforts, advanced gastric cancer still has a dismal prognosis with conventional treatment options. Immune checkpoint inhibitors have revolutionized the treatment landscape for many solid tumors. Amongst gastric cancer subtypes, tumors with microsatellite instability and Epstein Barr Virus positive tumors provide the strongest rationale for responding to immunotherapy. Various predictive biomarkers such as mismatch repair status, programmed death ligand 1 expression, tumor mutational burden, assessment of tumor infiltrating lymphocytes and circulating biomarkers have been evaluated. However, results have been inconsistent due to different methodologies and thresholds used. Clinical implementation therefore remains a challenge. The role of immune checkpoint inhibitors in gastric cancer is emerging with data from monotherapy in the heavily pre-treated population already available and studies in earlier disease settings with different combinatorial approaches in progress. Immune checkpoint inhibitor combinations with chemotherapy (CT), anti-angiogenics, tyrosine kinase inhibitors, anti-Her2 directed therapy, poly (ADP-ribose) polymerase inhibitors or dual checkpoint inhibitor strategies are being explored. Moreover, novel strategies including vaccines and CAR T cell therapy are also being trialed. Here we provide an update on predictive biomarkers for response to immunotherapy with an overview of their strengths and limitations. We discuss clinical trials that have been reported and trials in progress whilst providing an account of future steps needed to improve outcome in this lethal disease.

Amplification of the human epidermal growth factor receptor 2 (HER2) gene is associated with a microsatellite stable status in Chinese gastric cancer patients

BACKGROUND

Gastric cancer (GC) is one of the most common cancers worldwide. However, little is known about the combination of HER2 amplification and microsatellite instability (MSI) status in GC. This study aimed to analyze the correlation of HER2 amplification with microsatellite instability (MSI) status, clinical characteristics, and the tumor mutational burden (TMB) of patients.

METHODS

A total of 192 gastric cancer (GC) patients were enrolled in this cohort. To analyze genomic alterations (GAs), deep sequencing was performed on 450 target cancer genes. TMB was measured by an in-house algorithm. MSI status was inferred based on the MANTIS (Microsatellite Analysis for Normal-Tumor InStability) score.

RESULTS

The most frequently amplified genes in the GC patients included cyclin E1 (CCNE1), human epidermal growth factor receptor 2 (HER2), fibroblast growth factor receptor 2 (FGFR2), cyclin D1 (CCND1), fibroblast growth factor 19 (FGF19), fibroblast growth factor 3 (FGF3), and fibroblast growth factor 4 (FGF4). The frequency of HER2 amplification was 9.38% (18/192). HER2 amplification was higher in females than in males (14.52% vs. 6.92%, respectively, P=0.091), however, MSI was higher in males compared to females (7.69% vs. 4.84%, respectively, P=0.46). HER2 amplification was higher in metastatic loci compared to primary lesions (23.08% vs. 8.38%, respectively, P=0.079) and was lower in patients with high TMB (TMB-H) compared to those with low TMB (TMB-L) (4.0% vs. 11.35%, respectively, P=0.12). While the frequency of MSI in metastatic foci was higher than that in primary lesions (15.38% vs. 6.15%, respectively, P=0.48), MSI status was highly associated with TMB-H (20% vs. 0%, respectively, P=3.66×10-7). Furthermore, HER2 amplification was negatively correlated with MSI status in Chinese GC patients.

CONCLUSIONS

HER2 amplification was negatively correlated with TMB-H and MSI status, and MSI status was significantly associated with TMB-H in Chinese GC patients. These data suggested that HER2 amplification might be a negative indicator for GC immunotherapy.

A greater lymph node yield is required during pathological examination in microsatellite instability-high gastric cancer

Background

The impact of microsatellite status on lymph node (LN) yield during lymphadenectomy and pathological examination has never been assessed in gastric cancer (GC). In this study, we aimed to appraise the association between microsatellite instability-high (MSI-H) and LN yield after curative gastrectomy.

Methods

We retrospectively analyzed 1757 patients with GC undergoing curative gastrectomy and divided them into two groups: MSI-H (n = 185(10.5%)) and microsatellite stability (MSS) (n = 1572(89.5%)), using a five-Bethesda-marker (NR-24, BAT-25, BAT-26, CAT-25, MONO-27) panel. The median LN count and the percentage of specimens with a minimum of 16 LNs (adequate LN ratio) were compared between the two groups. The log odds (LODDS) of positive LN count (PLNC) to negative LN count (NLNC) and the target LN examined threshold (TLNT_(x%)) were calculated in both groups.

Results

Statistically significant differences were found in the median LN count between MSI-H and MSS groups for the complete cohort (30 vs. 28, p = 0.031), for patients undergoing distal gastrectomy (DG) (30 vs. 27, p = 0.002), for stage II patients undergoing DG (34 vs. 28, p = 0.005), and for LN-negative patients undergoing DG (28 vs. 24, p = 0.002). MSI-H was an independent factor for higher total LN count in patients undergoing DG (p = 0.011), but it was not statistically correlated to the adequate LN ratio. Statistically significant differences in PLNC, NLNC and LODDS were found between MSI-H GC and MSS GC (all p < 0.001). The TLNT_(90%) for MSI-H and MSS groups were 31 and 25, respectively. TLNT_(X%) of MSI-H GC was always higher than that of MSS GC regardless of the given value of X%.

Conclusions

MSI-H was associated with higher LN yield in patients undergoing gastrectomy for GC. Although MSI-H did not affect the adequacy of LN harvest, we speculate that a greater lymph node yield is required during pathological examination in MSI-H GC.

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.

Beyond the Guidelines: The Grey Zones of the Management of Gastric Cancer. Consensus Statements from the Gastric Cancer Italian Network (GAIN)

BACKGROUND

Management of gastric and gastroesophageal junction (GEJ) adenocarcinoma remains challenging, because of the heterogeneity in tumor biology within the upper gastrointestinal tract. Daily clinical practice is full of grey areas regarding the complexity of diagnostic, staging, and therapeutic procedures. The aim of this paper is to provide a guide for clinicians facing challenging situations in routine practice, taking a multidisciplinary consensus approach based on available literature.

METHODS

The GAIN (GAstric cancer Italian Network) group was established with the aims of reviewing literature evidence, discussing key issues in prevention, diagnosis, and management of gastric and GEJ adenocarcinoma, and offering a summary of statements. A Delphi consensus method was used to obtain opinions from the expert panel of specialists.

RESULTS

Forty-nine clinical questions were identified in six areas of interest: role of multidisciplinary team; risk factors; diagnosis; management of early gastric cancer and multimodal approach to localized gastric cancer; treatment of elderly patients with locally advanced resectable disease; and treatment of locally advanced and metastatic cancer.

CONCLUSIONS

The statements presented may guide clinicians in practical management of this disease.

Mismatch Repair Deficiency and Microsatellite Instability in Triple-Negative Breast Cancer: A Retrospective Study of 440 Patients

Purpose

To investigate the status of mismatch repair (MMR) and microsatellite instability (MSI) in triple-negative breast cancer (TNBC) and to examine correlations between MMR/MSI status and clinicopathological parameters.

Methods

We retrospectively collected tissue samples from 440 patients with TNBC and constructed tissue microarrays. Protein expression of MLH1, MSH2, MSH6, and PMS2 was detected by immunohistochemistry (IHC). We also analyzed 195 patient samples using MSI polymerase chain reaction (PCR) testing. Correlations between MSI status and clinicopathological parameters and prognosis were analyzed.

Results

The median age of the cohort was 49 years (range: 24–90 years) with a median follow-up period of 68 months (range: 1–170 months). All samples were positive for MLH1, MSH2, MSH6, and PMS2, except for one sample identified as MMR-deficient (dMMR) by IHC, with loss of MSH2 and intact MSH6 expression. MSI PCR revealed no case with high-frequency MSI (MSI-H), whereas 14 (7.2%) and 181 (92.8%) samples demonstrated low-frequency and absence of MSI events, respectively. The dMMR sample harbored low-frequency instability, as revealed by MSI PCR, and a possible EPCAM deletion in the tumor, as observed from next-generation sequencing. No correlations were detected between MMR or MSI status and clinicopathological parameters, programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) expression, or survival.

Conclusions

The incidence of dMMR/MSI-H is extremely low in TNBC, and rare discordant MSI PCR/MMR IHC results may be encountered. Moreover, MMR/MSI status may be of limited prognostic value. Further studies are warranted to explore other predictive immunotherapy biomarkers for TNBC.

Brazilian Group of Gastrointestinal Tumours' consensus guidelines for the management of oesophageal cancer

Oesophageal cancer is among the ten most common types of cancer worldwide. More than 80% of the cases and deaths related to the disease occur in developing countries. Local socio-economic, epidemiologic and healthcare particularities led us to create a Brazilian guideline for the management of oesophageal and oesophagogastric junction (OGJ) carcinomas. The Brazilian Group of Gastrointestinal Tumours invited 50 physicians with different backgrounds, including radiology, pathology, endoscopy, nuclear medicine, genetics, oncological surgery, radiotherapy and clinical oncology, to collaborate. This document was prepared based on an extensive review of topics related to heredity, diagnosis, staging, pathology, endoscopy, surgery, radiation, systemic therapy (including checkpoint inhibitors) and follow-up, which was followed by presentation, discussion and voting by the panel members. It provides updated evidence-based recommendations to guide clinical management of oesophageal and OGJ carcinomas in several scenarios and clinical settings.

Sexual Difference Matters: Females with High Microsatellite Instability Show Increased Survival after Neoadjuvant Chemotherapy in Gastric Cancer

Simple Summary

Here we report a sex- and age-specific analysis of 717 patients with gastric/gastro-esophageal adenocarcinomas treated with or without neoadjuvant chemotherapy (CTx) regarding overall survival (OS) and response to CTx. The analysis was also performed in molecular subtypes determined previously. Females demonstrated a significantly increased OS particularly in the group of patients treated with neoadjuvant CTx. Specifically in this patient group and taken into account the molecular subtypes, females with high microsatellite instability (MSI-H) showed the best survival followed by the male MSI-H, the female microsatellite stable (MSS) group and the male MSS group. Thus, we show an effect of sex on OS in gastric/gastro-esophageal cancer in particular for patients treated with neoadjuvant CTx. The superior survival of women with MSI-H tumors among the CTx patients implies that the combined consideration of these factors could contribute to an individualized treatment of the patients.

Abstract

We aimed to investigate patients with gastric/gastro-esophageal adenocarcinomas for sex- and age-specific differences regarding overall survival (OS) and response to neoadjuvant chemotherapy (CTx) under consideration of tumor specific molecular subtypes. Overall, 717 patients were analyzed, including 426 patients treated with and 291 treated without neoadjuvant CTx. Microsatellite instability (MSI) and Epstein-Barr virus positivity (EBV+) were determined previously. Females demonstrated a significantly increased OS (p = 0.035), particularly in the subgroup treated with CTx (p = 0.054). No significant differences regarding age were found. In the molecular subgroups, no sex-related differences were observed in the non-CTx group. However in the CTx group, females with MSI-high (H) tumors showed the best OS (p = 0.043), followed by the male MSI-H (p = 0.198) and female MSS (p = 0.114) compared to the male MSS group as reference. The interaction between sex and MSI in this patient group was noticeable (p = 0.053) and was included as a relevant factor in multivariable analyses. In conclusion, our results show an effect of sex on OS in gastric/gastro-esophageal cancer specifically for patients treated with neoadjuvant CTx. The superior survival of women with MSI-H tumors after neoadjuvant CTx implies that combined consideration of these factors could contribute to an individualized treatment of the patients.

Impact of microsatellite status on negative lymph node count and prognostic relevance after curative gastrectomy

BACKGROUND AND OBJECTIVES

The impact of microsatellite instability-high (MSI-H) phenotype on lymph node yield after lymphadenectomy has never been discussed in gastric cancer (GC). In this study, we aimed to assess the association of microsatellite status with negative lymph node count (NLNC) as well as its prognostic value.

METHODS

We retrospectively analyzed 1491 GC patients and divided them into two groups: MSI-H_GC (n = 141 [9.5%]) and microsatellite stability (MSS_GC ) (n = 1350 [90.5%]). The NLNC and survival data were compared between the two groups. The log odds of positive lymph nodes (LNs) to negative LNs and the target lymph node examined threshold (TLNT) were calculated in both groups.

RESULTS

A statistically significant difference was found in median NLNC (26 vs. 23, p < .001) between MSI-H_GC and MSS_GC patients. MSI status was an independent factor for NLNC (p < .001). NLNC showed positive prognostic value for cases with metastatic lymph node (LN₊ ) in both MSI-H_GC and MSS_GC groups. The TLNT_(90%) for MSI-H_GC and MSS_GC were 33 and 26, respectively.

CONCLUSIONS

MSI-H_GC was associated with higher NLNC in GC patients and this was independent of the presence of LN₊ . However, more LNs are needed during pathological examination to capture LN₊ cases in MSI-H_GC.

Gastric cancer is highly prevalent in Lynch syndrome patients with atrophic gastritis

BACKGROUND

Although gastric cancer is one of the Lynch syndrome (LS)-related tumors, the clinicopathological features of gastric cancer in patients with LS remain uncertain. To investigate the incidence risk and clinicopathological features of gastric neoplasms in LS, we conducted a retrospective cohort study in Japanese LS patients.

METHODS

LS patients with pathogenic mismatch repair (MMR) gene variants were extracted from the LS registry of the National Cancer Center Hospital, Japan. Cumulative risks of gastric neoplasm, including dysplasia and cancer, were estimated using the Kaplan-Meier method. Gastric atrophy was evaluated endoscopically and/or histologically. Immunohistochemical staining for MMR proteins was performed for all available specimens.

RESULTS

Of 118 eligible patients, 26 patients were diagnosed with 58 gastric neoplasms. The cumulative incidence of gastric neoplasm was 41.0% (95% confidence interval, 26.9-55.0) at the age of 70. Of these, 13 (50%) patients developed synchronous and/or metachronous multiple gastric neoplasms. Among the 49 gastric neoplasms available for detailed pathological evaluation, all were associated with intestinal metaplasia. Immunohistochemically, 42 (86%) were MMR-deficient. The individuals with gastric atrophy had a significantly higher risk of developing gastric neoplasms compared with those without gastric atrophy (26 cases/54 individuals vs. 0 cases/53 individuals) (P = 0.026).

CONCLUSION

LS patients, particularly those with atrophic gastritis, are at high risk of gastric neoplasm and often develop multiple tumors. Endoscopic surveillance for gastric cancer is recommended for LS patients, especially those with atrophic gastritis.

Prognostic impact of microsatellite instability in gastric cancer

Gastric cancer is a common and deadly cancer. Several factors are associated with its prognosis; however, controversy exists about the role of microsatellite instability (MSI). We aimed to determine the 5-year overall survival (OS) of MSI in gastric adenocarcinoma. A cross-sectional study was carried out on gastric adenocarcinoma in clinical stages I to III treated with D2 gastrectomy between 2010-2013. MSI was demonstrated by immunohistochemistry. We performed a survival analysis comparing cases with and without MSI. From 102 cases, 9.8% showed MSI. The median age was 63 years (range 33-91 years), and 57.8% were men. The more prevalent site of occurrence was the antrum (46.1%), 78.5% of the cases presented in stage III, 47.1% were of the diffuse type, 45.1% were of an intestinal type, and 7.8% were mixed. MSI cases were associated with lower clinical stages (stages I-II) and with better 5-year OS (100 vs. 47 months, p = 0.017). In a multivariate analysis, MSI was independently associated with better survival (HR = 0.209, 95% CI: 0.046-0.945, p = 0.042). MSI gastric cancers presented in early clinical stages and had favourable prognosis compared with non-MSI cancers.

[Neoadjuvant and perioperative treatment of gastric cancer, current studies and new biomarkers]

According to current German and European clinical practice guidelines perioperative chemotherapy is the recommended standard of care for localized gastric cancer beyond early cancers, i.e. in stage IB (T2 N0 M0 and T1 N1 M0) or greater. For patients who are able to tolerate intensive chemotherapy, the FLOT regimen (5-fluorouracil, folinic acid, oxaliplatin, docetaxel) should be administered preoperatively and postoperatively for four cycles each. Locally advanced nonmetastatic adenocarcinoma of the esophagogastric junction (AEG) should be treated with perioperative chemotherapy as for gastric cancer or alternatively with neoadjuvant chemoradiotherapy. The best approach for AEG is currently being investigated in ongoing clinical trials. The recommendation of perioperative treatment applies to all histopathological subtypes of gastric cancer. The article summarizes the contemporary data and provides an outlook on current progress in the field of medicinal perioperative treatment.

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.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

Inestabilidad microsatelital y cáncer gástrico

La inestabilidad microsatelital es causada por una alteración de los sistemas de reparación de apareamientoincorrecto, que puede afectar los microsatélites dentro de todo el genoma humano, produciendo errores en su replicación. Los estudios publicados, principalmente en la literatura inglesa, han encontrado que algunos tumores, como los gástricos, pueden expresar inestabilidad microsatelital. En la siguiente revisión de tema, se presenta una descripción de los sistemas de reparación de apareamientos incorrectos y su relación con la presencia de inestabilidad microsatelital en los tumores gástricos, así como su posible utilidad clínica, como factor asociado en la respuesta al tratamiento con inmunoterapia en los pacientes con dicha patología.

Cross-testing of major molecular markers indicates distinct pathways of tumorigenesis in gastric adenocarcinomas and synchronous gastrointestinal stromal tumors

Small subtype of the gastrointestinal stromal tumor (micro-GIST, MG) is usually asymptomatic and is frequently found incidentally in association with gastric adenocarcinoma (GAC). The background of this coincidence is still an open question. This study comprehensively characterized nine MGs and GACs present in the same surgical specimen by cross-testing the markers of the major pathogenetic pathways of both tumor types. All of the MGs were immunohistochemically positive for CD117/KIT, CD34, and DOG1. DOG1 was also detected in four GACs. Four MGs carried mutations in c-KIT (exons 9, 11, and 13) and two cases in PDGFRα (exon 18). None of the GACs carried activating mutations in c-KIT or PDGFRα. MMR immunopanel identified one GAC as microsatellite unstable tumor. No EBV-positive tumor was found. According to the TCGA molecular classification, one GAC was categorized in the MSI subgroup, three GACs in the genomically stable subgroup, and the rest into the chromosomal instability subgroup. Although a common carcinogenic effect cannot be ruled out, our data suggest a distinct molecular background in the evolvement of the synchronous MGs and GACs. The presence of a MG in gastric resection specimens may be indicative of the development of synchronous malignant tumors in or outside the stomach.

Microsatellite Status Affects Tumor Response and Survival in Patients Undergoing Neoadjuvant Chemotherapy for Clinical Stage III Gastric Cancer

Background

We assessed the association between microsatellite instability-high (MSI-H) and tumor response to neoadjuvant chemotherapy (NAC) as well as its prognostic relevance in patients with clinical stage III gastric cancer (cStage III GC).

Materials and Methods

The NAC + surgery and the control cohorts consisted of 177 and 513 cStage III GC patients, respectively. The clinical and pathological features were compared between patients with MSI-H [n=57 (8.3%)] and microsatellite stability or microsatellite instability-low (MSS/MSI-L) [n=633 (91.7%)]. Radiological and histological response to NAC were evaluated based on response evaluation criteria in solid tumors (RECIST) and tumor regression grade (TRG) systems, respectively. The log-rank test and Cox analysis were used to determine the survival associated with MSI status as well as tumor regression between the two groups in both NAC + surgery and the control cohorts.

Results

A statistically significant association was found between MSI-H and poor histological response to NAC (p=0.038). Significant survival priority of responders over poor-responders could only be observed in MSS/MSI-L but not in MSI-H tumors. However, patients with MSI-H had statistically significantly better survival compared to patients with MSS/MSI-L in both the NAC + surgery (hazard ratio=0.125, 95% CI, 0.017–0.897, p=0.037 ) and the control cohort (hazard ratio=0.479, 95% CI, 0.268–0.856, p=0.013).

Conclusion

MSI-H was associated with poorer regression and better survival after NAC for cStage III GC. TRG evaluation had prognostic significance in MSS/MSI-L but not in MSI-H. Further studies are needed to assess the value of NAC for cStage III GC patients with MSI-H phenotype.

Role and potential clinical utility of ARID1A in gastrointestinal malignancy

ARID1A (AT-rich interactive domain 1A) is a newly discovered tumor suppressor gene, and its encoded product is an important component of the SWI/SNF chromatin remodeling complex. ARID1A plays an important role in cell proliferation, invasion and metastasis, apoptosis, cell cycle regulation, epithelial mesenchymal transition, and the regulation of other of biological behaviors. Recently, ARID1A mutations have been increasingly reported in esophageal adenocarcinoma, gastric cancer, colorectal cancer, hepatocellular carcinoma, cholangiocarcinoma, pancreatic cancer, and other malignant tumors of the digestive system. This article reviews the relationship between ARID1A mutation and the molecular mechanisms of carcinogenesis, including microsatellite instability and the PI3K/ATK signaling pathway, and relates these mechanisms to the prognostic assessment of digestive malignancy. Further, this review describes the potential for molecular pathologic epidemiology (MPE) to provide new insights into environment-tumor-host interactions.

Genetic alterations in gastric cancer patients according to sex

To date, few reports have investigated the genetic alterations and clinicopathological features in gastric cancer (GC) according to sex. In total, 2673 GC patients receiving curative surgery were enrolled. Among the 2673 GC patients, 1979 (74.0%) patients were male. After propensity-score matching, 846 patients were enrolled for the analysis, including 423 males and 423 females. There was no significant difference in the clinicopathological features between the sexes. Regarding the initial recurrence pattern, the males were more likely to develop tumor recurrence and liver metastasis than the females, especially in stage III GC. Regarding the molecular analysis, the males had higher PD-L1 expression than the females, especially in stage III GC. In addition, the patients aged ≥ 65 years had higher PD-L1 expression than the patients younger than 65 years. The multivariate analysis demonstrated that sex was among the independent prognostic factors affecting overall survival (OS) and disease-free survival (DFS). Among the patients with liver metastases, PD-L1 expression was more common among the aged male patients. The males were associated with more tumor recurrence and higher PD-L1 expression than the females, especially in stage III GC. For GC patients with liver metastases, PD-L1 testing is recommended, especially among aged male patients.

Remnant gastric cancer: a neglected group with high potential for immunotherapy

PURPOSE

The importance of targeted therapy and interest in the study of predictive markers in gastric cancer (GC) have increased in recent years with the use of anti-HER2 therapy and immunotherapy with anti-PD1/PD-L1 for microsatellite instability (MSI) and PD-L1 + tumors. However, the behavior of remnant GC (RGC) in this scenario is poorly reported. Thus, this study aims to evaluate the clinicopathological characteristics and prognosis of RGC and its association with the expression of current markers for targeted therapy.

METHODS

All RGC resections performed in a single center from 2009 to 2019 were retrospectively reviewed. As a comparison group, 53 primary proximal GC (PGC) who underwent total D2-gastrectomy were selected. HER2, MSI status and PD-L1 expression were analyzed by immunohistochemistry. Combined Positive Score (CPS) was used to determine PD-L1 positivity.

RESULTS

A total of 40 RGC were included. RGC patients were older (p = 0.001), had lower BMI (p = 0.001) and number of resected lymph nodes (p < 0.001) compared to the PGC. Regarding markers expression, MSI was higher in RGC than PGC (27.5% vs 9.4%, p = 0.022). The frequency of CPS-positive was 32.5% and 26.4% in RGC and PGC, respectively (p = 0.522). HER2 positivity was 17.5% and 22.6% for RGC and PGC, respectively (p = 0.543). In survival analysis, DFS was better for RGC CPS-positive than RGC CPS-negative (p = 0.039) patients. There was no difference in survival considering MSI status.

CONCLUSION

RGC had higher incidence of MSI than PGC, and CPS-positive RGC was associated with better survival. The immunological profile of RGC patients suggests that they would be good candidates for immunotherapy.

Towards Personalization in the Curative Treatment of Gastric Cancer

Gastric cancer is the fifth most common cancer worldwide and has a high mortality rate. In the last decades, treatment strategy has shifted from an exclusive surgical approach to a multidisciplinary strategy. Treatment options for patients with resectable gastric cancer as recommended by different worldwide guidelines, include perioperative chemotherapy, pre- or postoperative chemoradiotherapy and postoperative chemotherapy. Although gastric cancer is a heterogeneous disease with respect to patient-, tumor-, and molecular characteristics, the current standard of care is still according to a one-size-fits-all approach. In this review, we discuss the background of the different treatment strategies in resectable gastric cancer including the current standard, the specific role of radiotherapy, and describe the current areas of research and potential strategies for personalization of therapy.

Clinicopathologic Characteristics and Long-Term Outcome of Gastric Cancer Patients with Family History: Seven-Year Follow-Up Study for Korean Health Check-Up Subjects

Methods

This study was conducted on asymptomatic healthy individuals who underwent upper gastrointestinal endoscopy for the purpose of GC screening. Patients who were diagnosed with GC between October 2003 and December 2013 at Seoul National University Hospital Healthcare System Gangnam Center were identified. Demographic and clinicopathologic characteristics were compared between the groups with and without FHx of GC. Overall survival (OS) and recurrence-free survival (RFS) were assessed as primary outcomes.

Results

There were no significant differences in tumor characteristics according to FHx of GC. However, preexisting adenoma was more frequent in patients with FHx than in those without FHx (14.5% vs. 6.3%, p = 0.035). The proportion of patients with microsatellite instability (MSI) was also higher in groups with FHx of GC (43.2% vs. 13.2%, p = 0.006). Helicobacter pylori infection rates of patients with FHx of GC tended to be higher although not significant (70.5% vs. 61.3%, p = 0.188). However, OS and RFS at 5 years of the GC patients with FHx were not significantly different from those of patients without FHx.

Conclusion

Preexisting adenoma and GC with MSI are more common in patients with FHx of GC than in those without. There were no significant differences in the survival rate according to FHx.

UR, Jesus VHF, Jr WLC, Prolla G. Brazilian Group of Gastrointestinal Tumours' consensus guidelines for the management of gastric cancer

Gastric cancer is among the ten most common types of cancer worldwide. Most cases and deaths related to the disease occur in developing countries. Local socio-economic, epidemiologic and healthcare particularities led us to create a Brazilian guideline for the management of gastric carcinomas. The Brazilian Group of Gastrointestinal Tumors (GTG) invited 50 physicians with different backgrounds, including radiology, pathology, endoscopy, nuclear medicine, genetics, oncological surgery, radiotherapy and clinical oncology, to collaborate. This document was prepared based on an extensive review of topics related to heredity, diagnosis, staging, pathology, endoscopy, surgery, radiation, systemic therapy and follow-up, which was followed by presentation, discussion, and voting by the panel members. It provides updated evidence-based recommendations to guide clinical management of gastric carcinomas in several scenarios and clinical settings.

Gastrointestinal cancers: current biomarkers in esophageal and gastric adenocarcinoma

Esophageal and gastric adenocarcinomas are frequently diagnosed at an advanced stage and have a dismal prognosis. Even in patients with potentially curative cancer, nearly 50% will develop recurrent disease despite aggressive treatments. A number of biomarkers currently guide treatment decisions for patients with esophageal and gastric adenocarcinoma and include human epidermal growth factor receptor 2 (HER2) amplification, mismatch repair deficiency/microsatellite instability (dMMR/MSI-H) and program death-ligand 1 (PD-L1) expression. This review will focus on the function, testing and FDA-approved targeted therapies for HER2, dMMR/MSI-H and PD-L1. In addition, a number of novel targets in esophageal and gastric cancer are being studied in clinical trials. Neurotrophic-tropomyosin receptor kinase (NTRK), claudin-18 (CLDN18)/Rho GTPase activating protein 26 (ARHGAP26) gene fusion, fibroblast growth factor receptor (FGFR), lymphocyte-activation gene 3 (LAG3) and T cell immunoglobulin and mucin-domain containing-3 (TIM3) will be briefly reviewed. Despite several biomarkers used in the selection of treatment therapies, treatment outcomes remain poor. Future research efforts will focus on the identification of new biomarkers, moving existing biomarkers into earlier lines of therapy, and evaluating new combinations of existing biomarkers and therapies.

PD-L1 and HER2 Expression in Gastroesophageal Cancer: a Matched Case Control Study

Immunotherapy with check-point inhibitors serves as a promising treatment strategy in patients with upper gastrointestinal (GI) tumors. Human epidermal growth factor receptor 2 (HER2) is the only identified therapeutic target in upper GI tumors, whose potential interaction with programmed death-ligand 1 (PD-L1) is unknown. The aim of this study was the investigation of PD-L1 and HER2 in upper GI tumors. We retrospectively identified patients with HER2 positive gastroesophageal cancers and matched them with a HER2 negative group. We investigated the tumor specimens for HER2 status and PD-L1 expression, with the following assessments being performed: i) staining of tumor cells in terms of tumor proportion score (TPS), ii) staining for tumor-associated immune cells (TAIs), iii) interface pattern and iv) combined positive score (CPS). Both HER2 positive and negative group consisted of 59 patients. Expression of PD-L1 in TAIs and interface pattern were associated with a favorable outcome (p = 0.02, HR = 0.8; p = 0.04, HR = 0.39; respectively) in patients with localized disease, whereas TPS was associated with an unfavorable outcome in patients with advanced tumor (p = 0.02, HR = 1.4). These effects were HER2 independent. PD-L1 expression in its different assessment is equally observed in HER2 positive and negative patients. Future studies will show whether dual inhibition of HER2 and PD-L1 improves survival of this selected patient population.

Better prognosis of gastric cancer patients with high levels of tumor infiltrating lymphocytes is counteracted by PD-1 expression

The prognostic potential of anti-tumor immune responses is becoming increasingly important in adenocarcinoma of the gastroesophageal junction and stomach (AGE/S) especially regarding the use of immune checkpoint inhibitors. This study analyzes for the first time the prognostic impact of tumor-infiltrating lymphocytes (TILs) and checkpoint inhibitors in a large Caucasian cohort in patients with AGE/S. We screened tissue samples from 438 therapy-naïve patients with AGE/S undergoing surgery between 1992 and 2005, examined in a tissue microarray (TMA) and stained against human CD3, CD4, CD8, PD-1, and PD-L1. Out of 438 tissue samples, 210 were eligible for multivariate analysis. This revealed that high infiltration with CD3+, CD4+, or CD8+ TILs was associated with an increased overall survival in AGE/S patients, which could only be confirmed in multivariate analysis for CD3 (HR: 0.326; p = .023). Independent improved survival was limited to gastric cancer patients and to early tumor stages as long as TILs did not express PD-1 (HR: 1.522; p = .021). Subgroup analyses indicate that TIL-dependent anti-tumor immune response is only effective in gastric cancer patients in early stages of disease in PD-1 negative TILs. Combined analysis of PD-1 and CD3 could serve as a prognostic marker for the clinical outcome of gastric cancer patients and could also be of interest for immunotherapy.

Mismatch Repair System Genomic Scars in Gastroesophageal Cancers: Biology and Clinical Testing

Alterations in the mismatch repair (MMR) system result in genomic instability, neoantigen production, and immune response in cancer. There is evidence that gastroesophageal tumors with MMR deficiency may be susceptible to immune-checkpoint inhibitors treatment, especially in those presenting at advanced-stage disease. Although a number of biomarkers have been developed in histology-agnostic settings to assess MMR status, there is evidence that a tumor-specific testing approach would improve the selection of patients for immunotherapy. However, no testing methods have been developed specifically for gastroesophageal cancers so far. Here, we discuss the state of the art, current advances, and future perspectives of MMR-related biomarkers’ biologic and clinical role in gastroesophageal cancers.

Immunophenotype based on inflammatory cells, PD-1/PD-L1 signalling pathway and M2 macrophages predicts survival in gastric cancer

Background

Immune response against cancer has prognostic impact but its role in gastric cancer is poorly known. The aim of the study was to assess the prognostic significance of immune cell score (CD3+, CD8+), tumour immune escape (PD-L1, PD-1) and immune tolerance (Clever-1).

Methods

After exclusion of Epstein-Barr virus positive (n = 4) and microsatellite instable (n = 6) tumours, the study included 122 patients with GC undergoing D2 gastrectomy. CD3+ and CD8+ based ICS, PD-L1, PD-1 and Clever-1 expressions were evaluated. Differences in survival were examined using Cox regression adjusted for confounders. The primary outcome was 5-year survival.

Results

The 5-year overall survival rate was 43.4%. High ICS was associated with improved overall survival (adjusted HR 0.48 (95% CI 0.26–0.87)) compared to low ICS. In the high ICS group, patients with PD-L1 expression (5-year survival 69.2 vs. 53.1%, p = 0.317), high PD-1 (5-year survival 70.6 vs. 55.3% p = 0.312) and high Clever-1 (5-year survival 72.0% vs. 45.5% (p = 0.070) had poor prognosis.

Conclusions

High ICS was associated with improved survival. In the high ICS group, patients with high PD-L1, PD-1 and Clever-1 had poor prognosis highlighting the importance of immune escape and immune tolerance in GC.

Gastrointestinal tissue-based molecular biomarkers: a practical categorisation based on the 2019 World Health Organization classification of epithelial digestive tumours

Molecular biomarkers have come to constitute one of the cornerstones of oncological pathology. The method of classification not only directly affects the manner in which patients are diagnosed and treated, but also guides the development of drugs and of artificial intelligence tools. The aim of this article is to organise and update gastrointestinal molecular biomarkers in order to produce an easy-to-use guide for routine diagnostics. For this purpose, we have extracted and reorganised the molecular information on epithelial neoplasms included in the 2019 World Health Organization classification of tumours. Digestive system tumours, 5th edn.

Current status of treatment with immune checkpoint inhibitors for gastrointestinal, hepatobiliary, and pancreatic cancers

The development of immune checkpoint inhibitors (ICIs) targeting cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), or programmed cell death protein ligand 1 (PD-L1) has revolutionized the treatment strategy in various types of cancers. In addition, recent studies have revealed that tumor microsatellite instability (MSI) status and tumor mutation burden (TMB) contribute significantly to the therapeutic response to anti-PD-1 monoclonal antibody (mAb), which led to an accelerated approval to pembrolizumab for the treatment of MSI-high or mismatch-repair-deficient solid tumors after conventional chemotherapies in 2017 and for the treatment of TMB-high solid tumors in 2020 by the United States Food and Drug Administration (FDA). In the field of gastrointestinal cancers, many clinical trials evaluating the safety and efficacy of various regimens such as ICI monotherapy, the combination of anti-CTLA-4 mAb and anti-PD-1/PD-L1 mAb, and combination of ICI and conventional chemotherapy or tyrosine kinase inhibitor have been reported or are in progress. This review summarizes MSI status and TMB in gastrointestinal, hepatobiliary, and pancreatic cancers, and provides the results of most relevant clinical trials evaluating ICIs. We also discuss the development of biomarkers required for improving the selection of patients with a high probability of benefiting from treatment with ICIs, and potential therapeutic strategies that could help to enhance anticancer responses of ICIs.

Challenges surrounding postoperative adjuvant chemotherapy for T2N0 gastric cancer

Determining the requirement for adjuvant chemotherapy in patients with stage IB gastric cancer (GC), and particularly for those with stage T2N0 (muscularis propria) disease, remains challenging. Patients with stage II/III disease benefit from postoperative adjuvant therapy; however, the randomized trials examining whether such therapy affords any survival benefit to patients with T2N0 disease are not sufficient. Current evidence suggests that not all patients with T2N0 disease should undergo such treatment, but only those with a high risk. To date, a number of retrospective studies have attempted to identify factors that are predictive of increased risk in an effort to guide adjuvant therapy-related clinical decision making. The National Comprehensive Cancer Network and the Chinese Society of Clinical Oncology have published guidelines regarding factors associated with increased patient risk. As a result, treatment decisions for patients with stage T2N0 disease are currently determined on an individualized basis, in light of risk factors and the potential benefits of treatment. The present review surveyed current evidence related to the treatment of patients with high-risk GC and highlighted the potential avenues for future investigated.