Synchronous metastatic gastric cancer-molecular background and clinical implications with special attention to mismatch repair deficiency

Current trends in the management of Gastro-oEsophageal cancers: Updates to the ESSO core curriculum (ESSO-ETC-UGI-WG initiative)

Gastro-oEsophageal Cancers (GECs) are severe diseases whose management is rapidly evolving. The European Society of Surgical Oncology (ESSO) is committed to the generation and spread of knowledge, and promotes the multidisciplinary management of cancer patients through its core curriculum. The present work discusses the approach to GECs, including the management of oligometastatic oesophagogastric cancers (OMEC), the diagnosis and management of peritoneal metastases from gastric cancer (GC), the management of Siewert Type II tumors, the importance of mesogastric excision, the role of robotic surgery, textbook outcomes, organ preserving options, the use of molecular markers and immune check-point inhibitors in the management of patients with GECs, as well as the improvement of current clinical practice guidelines for the management of patients with GECs. The aim of the present review is to provide a concise overview of the state-of-the-art on the management of patients with GECs and, at the same time, to share the latest advancements in the field and to foster the debate between surgical oncologists treating GECs worldwide. We are sure that our work will, at the same time, give an update to the advanced surgical oncologists and help the training surgical oncologists to settle down the foundations for their future practice.

Management of Microsatellite Instability High (MSI-H) Gastroesophageal Adenocarcinoma

BACKGROUND

Gastroesophageal cancer is a major cause of cancer-related mortality worldwide. Treatment of both early stage and advanced disease remains highly reliant on cytotoxic chemotherapy. About 4-24% of gastroesophageal cancers are microsatellite instability high (MSI-H). The MSI-H subtype is associated with favorable prognosis, resistance to cytotoxic chemotherapy, and sensitivity to immune checkpoint inhibitors (ICI). Recent studies have demonstrated promising activity of ICIs in the MSI-H subtype, resulting in fundamental changes in the management of MSI-H gastroesophageal adenocarcinoma.

PURPOSE

In this review, we discuss the prevalence, characteristics, prognosis, and management of MSI-H gastroesophageal adenocarcinoma, with a focus on recent and ongoing studies that have changed the landscape of treatment for the MSI-H subtype. We also discuss current challenges in the management of resectable and advanced MSI-H gastroesophageal cancer, including the need for more accurate biomarkers of response to ICI therapy.

Outcome and prognostic factors in patients undergoing salvage therapy for recurrent esophagogastric cancer after multimodal treatment

PURPOSE

Perioperative systemic treatment has significantly improved the outcome in locally advanced esophagogastric cancer. However, still the majority of patients relapse and die. Data on the optimal treatment after relapse are limited, and clinical and biological prognostic factors are lacking.

METHODS

Patients with a relapse after neoadjuvant/perioperative treatment and surgery for esophagogastric cancer were analyzed using a prospective database. Applied treatment regimens, clinical prognostic factors and biomarkers were analyzed.

RESULTS

Of 246 patients 119 relapsed. Among patients with a relapse event, those with an early relapse (< 6 months) had an inferior overall survival (OS 6.3 vs. 13.8 months, p < 0.001) after relapse than those with a late relapse (> 6 months). OS after relapse was longer in patients with a microsatellite-unstable (MSI) tumor. Systemic treatment was initiated in 87 patients (73% of relapsed pat.); among those OS from the start of first-line treatment was inferior in patients with an early relapse with 6.9 vs. 10.0 months (p = 0.037). In 27 patients (23% of relapsed pat.), local therapy (irradiation or surgical intervention) was performed due to oligometastatic relapse, resulting in a prolonged OS in comparison to patients without local therapy (median OS 35.2 months vs. 7.8 months, p < 0.0001). Multivariate analysis confirmed the prognostic benefit of the MSI status and a local intervention.

CONCLUSION

Patients relapsing after multimodal treatment have a heterogeneous prognosis depending on the relapse-free interval (if systemic treatment applied), extent of metastatic disease as well as MSI status. The benefit of additional local intervention after relapse should be addressed in a randomized trial.

Gene Regulatory Network Characterization of Gastric Cancer's Histological Subtypes: Distinctive Biological and Clinically Relevant Master Regulators

Gastric cancer (GC) molecular heterogeneity represents a major determinant for clinical outcomes, and although new molecular classifications have been introduced, they are not easy to translate from bench to bedside. We explored the data from GC public databases by performing differential gene expression analysis (DEGs) and gene network reconstruction to identify master regulators (MRs), as well as a gene set analysis (GSA) to reveal their biological features. Moreover, we evaluated the association of MRs with clinicopathological parameters. According to the GSA, the Diffuse group was characterized by an epithelial-mesenchymal transition (EMT) and inflammatory response, while the Intestinal group was associated with a cell cycle and drug resistance pathways. In particular, the regulons of Diffuse MRs, such as Vgll3 and Ciita, overlapped with the EMT and interferon-gamma response, while the regulons Top2a and Foxm1 were shared with the cell cycle pathways in the Intestinal group. We also found a strict association between MR activity and several clinicopathological features, such as survival. Our approach led to the identification of genes and pathways differentially regulated in the Intestinal and Diffuse GC histotypes, highlighting biologically interesting MRs and subnetworks associated with clinical features and prognosis, suggesting putative actionable candidates.

The concept of oligometastatic disease in gastric cancer: reality or fiction?

Positive results in the RENAISSANCE Trial will establish oligometastatic gastric cancer as a real independent entity where total surgical treatment will become the standard of care.

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.

Occurrence of High Microsatellite-Instability/Mismatch Repair Deficiency in Nearly 2,000 Human Adenocarcinomas of the Gastrointestinal Tract, Pancreas, and Bile Ducts: A Study From a Large German Comprehensive Cancer Center

INTRODUCTION

Knowledge of the high microsatellite-instability (MSI-H)/mismatch repair deficiency (MMRd) status is of increasing interest for personalized neoadjuvant or adjuvant therapy planning. Only a few studies are available on MSI-H distribution in the Northern European Caucasian patient population. In this study, we focused on a large cohort of tumors of the upper gastrointestinal tract.

MATERIALS AND METHODS

Surgical material from a total of 1,965 patients was analyzed for MSI-H/MMRd status (including 1,267 carcinomas of the esophagus or stomach). All tumors were analyzed with an internationally recommended immunohistochemical panel consisting of four antibodies (MLH1, MSH2, PMS2, and MSH6). The results were molecularly objectified.

RESULTS

Adenocarcinomas with MSI-H/MMRd were detected with the following distribution: esophagus (1.4%), stomach (8.3%), small intestine (18.2%), large intestine (8.5%), intrahepatic bile ducts (1.9%), and pancreas (0%). In case of gastric tumors with MSI-H/MMRd, neoadjuvant therapy did not influence the prognosis of patients (p = 0.94). Within all tumor entities with MSI-H/MMRd, patients with a UICC stage 4 were also represented. In this advanced stage, 11.7% of patients with MSS tumors were diagnosed compared to 0.5% of patients with MSI-H tumors relative to the entire tumor collective.

DISCUSSION

In this study, the proportion of MSI-H/MMRd tumors in the stomach is smaller than would have been expected in knowledge of the data published by TCGA or AGRC. Negative prognostic effects regarding MSI-H status and neoadjuvant therapy as described by the MAGIC study group were not seen in our cohort. The extent to which the MSI-H/MMRd status should be known for neoadjuvant therapy planning must be clarified in prospective studies in the future. At present, there is no convincing data to dispense the neoadjuvant therapy for gastric carcinoma. Due to the very convincing, positive data regarding the response rates of MSI-H tumors to treatment with PD1/PD-L1 inhibitors, every metastatic carcinoma of the gastrointestinal tract should be tested for its MSI-H status.

Surgical management of oligometastatic disease in gastric cancer

A distinctive subset of metastatic gastric cancer (MGC) is oligometastatic disease (OMD), which is characterized by metastatic lesions limited in number and location. Although growing evidence mainly based on retrospective analysis or single center case series has shown favorable prognosis in the management of OMD in gastric cancer with aggressive local treatment, no existing guidelines explicitely address the definition of OMD and there are still controversial opinions on how to proceed in a new era with more effective systemic therapy selection. In this review, we present the current advances and evidence as well as controversial on the management of OMD in MGC, including the definition, diagnosis, local aggressive treatments especially surgery, prognostic factors, current ongoing randomized clinical studied as well as challenges facing the field.

MSI as a predictive factor for treatment outcome of gastroesophageal adenocarcinoma

Gastroesophageal cancers are a major cause of death worldwide and treatment outcomes remain poor. Adequate predictive biomarkers have not been identified. Microsatellite instability (MSI) as a result of mismatch repair deficiency is present in four to twenty percent of gastroesophageal cancers and has been associated with favorable survival outcomes compared to microsatellite stable tumors. This prognostic advantage may be related to immunosurveillance, which may also explain the favorable response to immune checkpoint inhibition observed in MSI high (MSI-H) tumors. The value of conventional cytotoxic treatment in MSI-H tumors is unclear and results on its efficacy range from detrimental to beneficial effects. Here the recent data on MSI as a predictive factor for outcome of gastroesophageal cancer treatment is reviewed.

Gastroesophageal cancer: Navigating the immune and genetic terrain to improve clinical outcomes

Recent advances in our understanding of the molecular biology of gastric and oesophageal cancers have shown that gastroesophageal adenocarcinoma should be considered as one disease spectrum. Clinical management of these cancers is challenging, with poor outcomes in both early and late disease settings. Certain molecular subsets of gastroesophageal adenocarcinoma demonstrate features that suggest immunotherapy could be an effective treatment. Immunogenetic markers, including mismatch repair deficiency, PD-L1 status and tumour infiltrating lymphocytes influence overall prognosis. They may also determine the response to adjuvant and neoadjuvant conventional chemotherapy. Initial results from immunotherapy trials for gastroesophageal cancer have however been mixed, with poor overall responses in the first- and second-line settings. This review aims to discuss how better understanding of these immune and genetic interactions may lead to better selection of patients for conventional and immune based therapies, and therefore improve patient outcomes. We also discuss the challenges in implementing this new understanding in routine practice, and the current limitations of immune based treatments for gastroesophageal cancer.

Oligometastatic gastric cancer: An emerging clinical entity with distinct therapeutic implications

Gastric cancer (GC) remains responsible for a high burden worldwide being the third leading cause of cancer-related mortality. Most of patients present at an advanced stage at diagnosis and are thus candidates to standard chemotherapy resulting in median survival of less than 1 year. Oligometastatic gastric cancer is an increasingly recognized clinical entity characterized by limited metastatic spread that has been showing to benefit from aggressive multimodality strategies encompassing chemotherapy and surgery. The ongoing RENAISSANCE/AIO-FLOT5 (NCT02578368) phase III trial is aimed at evaluating if perioperative chemotherapy with FLOT in combination with surgical resection of the primary tumour and metastases could become the new standard of care for oligometastatic GC. In the meantime, in addition to currently available clinical parameters, the emerging predictive/prognostic role of biomarkers such mismatch repair deficiency/microsatellite instability high status needs to be specifically addressed also in this subgroup of GC to assist in patient selection.

[Epidemiology of microsatellite instability across solid neoplasms]

Microsatellite instability (MSI) is a predictive biomarker for the efficacy of immune checkpoint inhibitors, regardless of the tumor type. While clinical characteristics of MSI cancer patients have been largely described in tumor localizations frequently associated with this genetic phenotype (i.e. colorectal cancer, endometrial cancer), it remains poorly characterized in other neoplasms. Pan-tumor high-throughput genome sequence analyses have contributed to the broadening of knowledge about the landscape of MSI. This review aims at synthetizing the literature concerning the frequency of MSI status in solid cancers, according to the cancer stage and the hereditary or sporadic origin of the mismatch repair deficiency. We then check for other cancers frequently associated with MSI and describe the clinical and pathological characteristics that should suggest a MSI phenotype.

From Tumor Immunology to Immunotherapy in Gastric and Esophageal Cancer

Esophageal and gastric cancers represent tumors with poor prognosis. Unfortunately, radiotherapy, chemotherapy, and targeted therapy have made only limited progress in recent years in improving the generally disappointing outcome. Immunotherapy with checkpoint inhibitors is a novel treatment approach that quickly entered clinical practice in malignant melanoma and renal cell cancer, but the role in esophageal and gastric cancer is still poorly defined. The principal prognostic/predictive biomarkers for immunotherapy efficacy currently considered are PD-L1 expression along with defects in mismatch repair genes resulting in microsatellite instability (MSI-H) phenotype. The new molecular classification of gastric cancer also takes these factors into consideration. Available reports regarding PD-1, PD-L1, PD-L2 expression and MSI status in gastric and esophageal cancer are reviewed to summarize the clinical prognostic and predictive role together with potential clinical implications. The most important recently published clinical trials evaluating checkpoint inhibitor efficacy in these tumors are also summarized.

The Thomsen-Friedenreich Antigen: A Highly Sensitive and Specific Predictor of Microsatellite Instability in Gastric Cancer

Microsatellite instability (MSI) is a distinct molecular subtype of gastric cancer. In recent years, the clinical consequences of MSI and the therapeutic opportunities to target this peculiar cancer subtype became evident. However, despite the importance of MSI for the stratification of patients, the time and resources required for diagnosis still present an obstacle. In an attempt to identify a new marker for MSI in gastric cancer, we evaluated the expression of five cancer-associated glycan epitopes in a cohort of 13 MSI and 17 microsatellite stable (MSS) cases. Our analysis revealed a highly significant (p < 0.001) association between the expression of the Thomsen-Friedenreich (TF) antigen and MSI status. Hence, we present here the identification of the first single marker for MSI in gastric cancer, excelling with a specificity of 94% (16/17), sensitivity of 69.2% (9/13), negative predictive value of 80% (16/20), and positive predictive value of 90% (9/10). The TF antigen, detected by simple antibody-based assays, is highly specific for carcinoma being undetectable in gastric healthy and premalignant epithelia. This finding lays the basis for new studies and holds promise in improving the rapid identification of MSI in the clinical setting.