Mismatch repair deficiency may affect clinical outcome through immune response activation in metastatic gastric cancer patients receiving first-line chemotherapy

Potent therapeutic strategy in gastric cancer with microsatellite instability-high and/or deficient mismatch repair

Gastric cancer (GC) is a common malignancy that presents challenges in patient care worldwide. The mismatch repair (MMR) system is a highly conserved DNA repair mechanism that protects genome integrity during replication. Deficient MMR (dMMR) results in an increased accumulation of genetic errors in microsatellite sequences, leading to the development of a microsatellite instability-high (MSI-H) phenotype. Most MSI-H/dMMR GCs arise sporadically, mainly due to MutL homolog 1 (MLH1) epigenetic silencing. Unlike microsatellite-stable (MSS)/proficient MMR (pMMR) GCs, MSI-H/dMMR GCs are relatively rare and represent a distinct subtype with genomic instability, a high somatic mutational burden, favorable immunogenicity, different responses to treatment, and prognosis. dMMR/MSI-H status is a robust predictive biomarker for treatment with immune checkpoint inhibitors (ICIs) due to high neoantigen load, prominent tumor-infiltrating lymphocytes, and programmed cell death ligand 1 (PD-L1) overexpression. However, a subset of MSI-H/dMMR GC patients does not benefit from immunotherapy, highlighting the need for further research into predictive biomarkers and resistance mechanisms. This review provides a comprehensive overview of the clinical, molecular, immunogenic, and therapeutic aspects of MSI-H/dMMR GC, with a focus on the impact of ICIs in immunotherapy and their potential as neoadjuvant therapies. Understanding the complexity and diversity of the molecular and immunological profiles of MSI-H/dMMR GC will drive the development of more effective therapeutic strategies and molecular targets for future precision medicine.

The tumor immune composition of mismatch repair deficient and Epstein-Barr virus-positive gastric cancer: A systematic review

BACKGROUND

Gastric cancer (GC), known for its unfavorable prognosis, has been classified in four distinct molecular subtypes. These subtypes not only exhibit differences in their genome and transcriptome but also in the composition of their tumor immune microenvironment. The microsatellite instable (MSI) and Epstein-Barr virus (EBV) positive GC subtypes show clear clinical benefits from immune checkpoint blockade, likely due to a neoantigen-driven and virus-driven antitumor immune response and high expression of immune checkpoint molecule PD-L1. However, even within these subtypes response to checkpoint inhibition is variable, which is potentially related to heterogeneity in the tumor immune microenvironment (TIME) and expression of co-inhibitory molecules. We conducted a systematic review to outline the current knowledge about the immunological features on the TIME of MSI and EBV + GCs.

METHODS

A systematic search was performed in PubMed, EMBASE and Cochrane Library. All articles from the year 1990 and onwards addressing immune features of gastric adenocarcinoma were reviewed and included based on predefined in- and exclusion criteria.

RESULTS

In total 5962 records were screened, of which 139 were included that reported immunological data on molecular GC subtypes. MSI and EBV + GCs were reported to have a more inflamed TIME compared to non-MSI and EBV- GC subtypes. Compared to microsatellite stable (MSS) tumors, MSI tumors were characterized by higher numbers of CD8 + and FoxP3 + T cells, and tumor infiltrating pro- and anti-inflammatory macrophages. HLA-deficiency was most common in MSI tumors compared to other molecular GC subtypes and associated with lower T and B cell infiltrates compared to HLA-proficient tumors. EBV + was associated with a high number of CD8 + T cells, Tregs, NK cells and macrophages. Expression of PD-L1, CTLA-4, Granzyme A and B, Perforin and interferon-gamma was enriched in EBV + tumors. Overall, MSI tumors harbored a more heterogeneous TIME in terms of immune cell composition and immune checkpoints compared to the EBV + tumors.

DISCUSSION AND CONCLUSION

MSI and EBV + GCs are highly Handbook for Conducting a Literature-Based Health Assessment Using OHAT Approach for Systematic Review and Evidence Integration.; 2019pro-inflammatory immune cell populations. Although studies on the direct comparison of EBV + and MSI tumors are limited, EBV + tumors show less intra-subgroup heterogeneity compared to MSI tumors. More studies are needed to identify how Intra-subgroup heterogeneity impacts response to immunotherapy efficacy.

Global burden, risk factors, clinicopathological characteristics, molecular biomarkers and outcomes of microsatellite instability-high gastric cancer

Microsatellite instability-high (MSI-H) has gained considerable interests since it was approved as a tumor-agnostic biomarker in immunotherapy. However, the reported characteristics of MSI-H gastric cancer (GC) are inconsistent due to the biological complexity. Here, we aim to clarify the prevalence, risk factors, clinicopathological/molecular features and outcomes of MSI-H GC though a comprehensive review on 43246 patients from 134 cohorts. Overall, the proportion of MSI-H GC was 14.5% (95% CI, 13.3%-15.8%). Patients with MSI-H GC were less likely to have Epstein-Barr virus infection. High incidences of MSI-H GC were associated with female, older age, lower gastric body, Lauren intestinal histology, WHO tubular and mucinous subtypes, and early disease stage. Additionally, patients with MSI-H GC harbored more KRAS mutation, PD-L1 positivity, CD8 overexpression, and higher TMB, but less HER2 positivity and TP53 mutation. When treated with conventional strategy, the 5-year survival rates in MSI-H patients (70.3%) and MSI-L/MSS patients (43.7%) were significantly different (p<0.001). Patients with MSI-H GC derived larger benefit from immunotherapy in term of overall survival (pInteraction<0.001) and objective response (pInteraction=0.02). Since the prevalence of MSI-H GC is relatively high and associated with distinct clinicopathological and molecular characteristics, MSI testing should be conducted during standard diagnostical activity. Moreover, giving MSI-H tumors are often diagnosed at early stage and have favorable outcomes, less aggressive treatment strategies may be considered in clinical practice. In summary, this panoramic review may assist in design and/or interpretation of clinical trials, provide references in drug development, and constitute complementary information in drafting the clinical practice guideline.

Low incidence of microsatellite instability in gastric cancers and its association with the clinicopathological characteristics: a comparative study

Gastric cancer is a complex heterogeneous disease with different molecular subtypes that have clinical implications. It is characterized by high mortality rates and limited effective therapies. Microsatellite instability (MSI) has been recognized as a subgroup with a good prognosis based on TCGA and ACRG categorizations. Besides its prognostic and predictive value, gastric cancers with high MSI exhibit different clinical behaviors. The prevalence of high MSI has been assessed in gastric cancer worldwide, especially in East Asia, but there is a lack of such information in the Middle East. Therefore, this study aimed to investigate the incidence and status of MSI in Iranian gastric cancer patients using 53 samples collected from 2015 to 2020 at Taleghani Hospital Medical Center. DNA from tumoral and normal tissues were extracted and assessed through multiplex-PCR based on five mononucleotide repeats panel. Clinicopathological variables, including age, sex, Lauren classification, lymph node involvement, TNM stage, differentiation, localization, and tumor size, were also analyzed. With 2 males and 2 females, high microsatellite instability represented a small subgroup of almost 7.5% of the samples with a median age of 60.5 years. High microsatellite instability phenotypes were significantly associated with patients aged 68 years and older (p‑value of 0.0015) and lower lymph node involvement (p‑value of 0.0004). Microsatellite instability was also more frequent in females, with distal gastric location, bigger tumor size, and in the intestinal type of gastric cancer rather than the diffuse type.

Advances and key focus areas in gastric cancer immunotherapy: A comprehensive scientometric and clinical trial review (1999-2023)

BACKGROUND

Gastric cancer (GC) is the sixth most common cancer and third leading cause of cancer-related deaths worldwide. Current treatments mainly rely on surgery- and chemotherapy-based systemic; however, the prognosis remains poor for advanced disease. Recent studies have suggested that immunotherapy has significant potential in cancer therapy; thus, GC immunotherapy may improve quality of life and survival for patients with this disease.

AIM

To provide a comprehensive overview of the knowledge structure and research hotspots of GC immunotherapy.

METHODS

We conducted a bibliometric analysis of publications on immunotherapy related to GC in the Web of Science Core Collection database. We analyzed 2013 pub-lications from 1999 to February 1, 2023, using the VOSviewer and CiteSpace software. We assessed publication and citation distributions using the WoS platform and explored research countries, institutions, journals, authors, references, and keywords (co-occurrence, timeline view, and burst analysis). In addition, we examined 228 trials on immunotherapy, 137 on adoptive cell therapy, 274 on immune checkpoint inhibitors (ICIs), and 23 on vaccines from ClinicalTrials.gov and the International Clinical Trials Registry Platform. The Impact Index Per Article for the top ten high-cited papers collected from Reference Citation Analysis (RCA) are presented.

RESULTS

Our bibliometric analysis revealed that the study of immunotherapy in GC has developed rapidly in recent years. China accounted for almost half the publications, followed by the United States. The number of publications in recent years has been growing continuously, and most institutions and authors with the most publications are from China. The main keywords or clusters identified were "tumor microenvironment", "adoptive immunotherapy", "dendritic therapy", and "microsatellite instability".

CONCLUSION

Our analysis of 2013 publications indicated that immunotherapy for GC has led to several new developments in recent years. Considerable progress has been made in vaccinations, immune checkpoint therapy, and adoptive cellular therapy. In particular, ICIs and chimeric antigen receptor T-cells are novel options for the treatment of GC. We suggest that the combination of ICIs, chemotherapy, targeted therapy, and other immunotherapies should be the primary research direction in the future.

Perioperative Chemotherapy Could Not Improve the Prognosis of Gastric Cancer Patients With Mismatch Repair Deficiency: A Multicenter, Real-World Study

INTRODUCTION

To date, the role of deficient mismatch repair (dMMR) remains to be proven in gastric cancer, and it is difficult to judge its value in clinical application. Our study aimed to investigate how MMR status affected the prognosis in patients with gastrectomy, as well as the efficacy of neoadjuvant chemotherapy and adjuvant chemotherapy in patients with dMMR with gastric cancer.

MATERIALS AND METHODS

Patients with gastric cancer with certain pathologic diagnosis of dMMR or proficient MMR (pMMR) using immunohistochemistry from 4 high-volume hospitals in China were included. Propensity score matching was used to match patients with dMMR or pMMR in 1:2 ratios. Overall survival (OS) and progression-free survival (PFS) curves were plotted using the Kaplan-Meier method and compared statistically using the log-rank test. Univariate and multivariate Cox proportional hazards models based on hazard ratios (HRs) and 95% confidence intervals (CIs) were used to determine the risk factors for survival.

RESULTS

In total, data from 6176 patients with gastric cancer were ultimately analyzed, and loss of expression of one or more MMR proteins was observed in 293 patients (293/6176, 4.74%). Compared to patients with pMMR, patients with dMMR are more likely to be older (≥66, 45.70% vs. 27.94%, P < .001), distal location (83.51% vs. 64.19%, P < .001), intestinal type (42.21% vs. 34.46%, P < .001), and in the earlier pTNM stage (pTNM I, 32.79% vs. 29.09%, P = .009). Patients with gastric cancer with dMMR showed better OS than those with pMMR before PSM (P = .002); however, this survival advantage was not observed for patients with dMMR after PSM (P = .467). As for perioperative chemotherapy, results of multivariable Cox regression analysis showed that perioperative chemotherapy was not an independent prognostic factor for PFS and OS in patients with dMMR with gastric cancer (HR = 0.558, 95% CI, 0.270-1.152, P = .186 and HR = 0.912, 95% CI, 0.464-1.793, P = .822, respectively).

CONCLUSION

In conclusion, perioperative chemotherapy could not prolong the OS and PFS of patients with dMMR with gastric cancer.

Assessment of the reliability of MSI status and dMMR proteins deficiency screening on endoscopic biopsy material in esophagus and gastric adenocarcinoma

BACKGROUND

Microsatellite instability (MSI) is a negative predictive factor for neoadjuvant chemotherapy in resectable oesogastric adenocarcinoma and a crucial determinant for immunotherapy. We aimed to evaluate reliability of dMMR/MSI status screening performed on preoperative endoscopic biopsies.

METHODS

Paired pathological samples from biopsies and surgical specimen of oesogastric adenocarcinoma were retrospectively collected between 2009 and 2019. We compared dMMR status obtained by immunohistochemistry (IHC) and MSI status by PCR. dMMR/MSI status on surgical specimen was considered as reference.

RESULTS

PCR and IHC were conclusive on biopsies respectively for 53 (96.4%) and 47 (85.5%) of the 55 patients enrolled. IHC was not contributive for 1 surgical specimen. A third reading of IHC was carried out for 3 biopsies. MSI status was observed in 7 (12.5%) surgical specimens. When analyses were contributive, sensitivity and specificity of biopsies for dMMR/MSI were respectively 85% and 98% for PCR vs. 86% and 98% for IHC. Concordance rate between biopsies and surgical specimen was 96.2% for PCR and 97.8% for IHC.

CONCLUSIONS

Endoscopic biopsies are a suitable source of tissue for dMMR/MSI status determination in oesogastric adenocarcinoma which should be routinely performed at diagnosis to better adapt neoadjuvant treatment.

MINIABSTRACT

By comparison of dMMR phenotype obtained by immunohistochemistry and MSI status by PCR between match-paired samples of oesogastric cancer's endoscopic biopsies and surgical specimen, we observed that biopsies are a suitable source of tissue for dMMR/MSI status determination.

Correlation between mismatch repair and survival of patients with gastric cancer after 5-FU-based adjuvant chemotherapy

BACKGROUND

Almost all adjuvant chemotherapy regimens for gastric cancer recommended by guidelines are fluorouracil (5-FU) based, and 5-FU-based adjuvant chemotherapy plays an important role in reducing the recurrence of gastric cancer after surgery. However, the effect of mismatch repair (MMR) status on survival after 5-FU-based adjuvant chemotherapy in patients with gastric cancer remains controversial.

MATERIALS AND METHODS

We prospectively included patients with gastric cancer who underwent radical gastrectomy between March 14, 2017 and September 30, 2021. The included patients received 5-FU-based adjuvant chemotherapy or surgery alone. The MMR status of patients was divided into MMR proficient (pMMR) and MMR defective (dMMR) according to four MMR proteins. Peripheral blood was collected for systemic inflammation analysis. The main purpose of this study was to analyze the effect of MMR status on survival after 5-FU-based adjuvant chemotherapy in patients with gastric cancer. We also analyzed the differences in systemic inflammation levels in different MMR status and their impact on survival.

RESULTS

A total of 479 patients were enrolled, with a median follow-up period of time was 36 months. In the surgery alone group, dMMR gastric cancer had better disease-free survival (DFS) (hazard ratio [HR] = 4.33, 95% confidence interval [CI] 1.25-15.02, p = 0.02) than pMMR, and in the adjuvant chemotherapy group, there was no significant difference in DFS (HR = 1.16, 95% CI 0.65-2.07, p = 0.61) between dMMR and pMMR gastric cancer. The same results were seen for overall survival (OS). In addition, the result show that in the dMMR group, there was no difference in DFS (HR = 1.62, 95% CI 0.46-5.77, p = 0.45) between patients receiving adjuvant chemotherapy and those receiving surgery alone. In the pMMR group, the DFS values (HR = 0.59, 95%CI 0.35-0.99, p = 0.04) of patients receiving adjuvant chemotherapy were better than those of patients receiving surgery alone, and the same results were observed for OS. In addition, among pMMR patients, patients with a low platelet lymphocyte ratio (PLR) who received 5-FU adjuvant chemotherapy and those with a low neutrophil lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) who received surgery alone had better DFS and OS.

CONCLUSION

To our knowledge, this is the first prospective study to specifically explore the correlation between MMR and survival of patients with gastric cancer after 5-FU-based adjuvant chemotherapy. The results showed that gastric cancer patients with pMMR can benefit from 5-FU-based adjuvant chemotherapy, but those with dMMR cannot. Among pMMR patients, lower PLR and SII values with surgery alone and lower NLRs in those receiving 5-FU-based adjuvant chemotherapy were associated with higher DFS and OS.

Identification of a novel MSI-related ceRNA network for predicting the prognosis and immunotherapy response of gastric cancer

BACKGROUND

Mounting evidence has underscored the pivotal role of the competitive endogenous RNA (ceRNA) regulatory networks among various cancers. However, the behavior characteristics and complexity of the ceRNA network in Gastric cancer (GC) remains unclear. In this study, we aimed to clarify a Microsatellite instability (MSI)-related ceRNA regulatory network and identify potential prognostic markers associated with GC.

METHODS AND RESULTS

We extracted transcriptome data of GC patients from The Cancer Genome Atlas (TCGA) and identified differentially expressed lncRNAs, miRNAs and mRNAs based on MSI status. A hub ceRNA network including 1 lncRNAs (MIR99AHG), 2 miRNAs and 26 mRNAs specific to MSI was established in GC. We further constructed a prognostic model with seven target mRNAs by Lasso Cox regression, which yielded AUC values of 0.76. The prognostic model was further validated in an external independent dataset that integrated three GEO datasets. The characterization of immune cell infiltration and immunotherapy effects between high-risk and low-risk groups were then analyzed. Immune cell infiltration was significantly different between high- and low-risk groups based on risk scores. GC patients with lower risk scores correlated with better immune checkpoint inhibitor therapy (ICI) response. We further validated the expression and regulatory relationship of the ceRNA network in vitro experiments, and also confirmed the relationship between MIR99AHG and PD-L1.

CONCLUSIONS

Our research provides in-depth insights on the role of MSI-related ceRNA in GC and the prognosis and ICIs therapy response of GC patients can be assessed by the risk model based on MSI-related ceRNA network.

Biomarkers for chemotherapy and drug resistance in the mismatch repair pathway

Drugs targeting DNA repair have developed rapidly in cancer therapy, and numerous inhibitors have already been utilized in preclinical and clinical stages. To optimize the selection of patients for treatment, it is essential to discover biomarkers to anticipate chemotherapy response. The DNA mismatch repair (MMR) pathway is closely correlated with cancer susceptibility and plays an important role in the occurrence and development of cancers. Here, we give a concise introduction of the MMR genes and focus on the potential biomarkers of chemotherapeutic response and resistance. It has been clarified that the status of MMR may affect the outcome of chemotherapy. However, the specific underlying mechanisms as well as contradictory results continue to raise considerable controversy and concern. In this review, we summarize the current literature to provide a general overview.

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.

Mismatch repair deficiency, chemotherapy and survival for resectable gastric cancer: an observational study from the German staR cohort and a meta-analysis

PURPOSE

In a post hoc analysis of the MAGIC trial, patients with curatively resected gastric cancer (GC) and mismatch repair (MMR) deficiency (MMRd) had better median overall survival (OS) when treated with surgery alone but worse median OS when treated with additional chemotherapy. Further data are required to corroborate these findings.

METHODS

Between April 2013 and December 2018, 458 patients with curatively resected GC, including cancers of the esophagogastric junction Siewert type II and III, were identified in the German centers of the staR consortium. Tumor sections were assessed for expression of MLH1, MSH2, MSH6 and PMS2 by immunohistochemistry. The association between MMR status and survival was assessed. Similar studies published up to January 2021 were then identified in a MEDLINE search for a meta-analysis.

RESULTS

MMR-status and survival data were available for 223 patients (median age 66 years, 62.8% male), 23 patients were MMRd (10.3%). After matching for baseline clinical characteristics, median OS was not reached in any subgroup. Compared to perioperative chemotherapy, patients receiving surgery alone with MMRd and MMRp had a HR of 0.67 (95% CI 0.13-3.37, P = 0.63) and 1.44 (95% CI 0.66-3.13, P = 0.36), respectively. The meta-analysis included pooled data from 385 patients. Compared to perioperative chemotherapy, patients receiving surgery alone with MMRd had an improved OS with a HR of 0.36 (95% CI 0.14-0.91, P = 0.03), whereas those with MMRp had a HR of 1.18 (95% CI 0.89-1.58, P = 0.26).

CONCLUSION

Our data support a positive prognostic effect for MMRd in GC patients treated with surgery only and a differentially negative prognostic effect in patients treated with perioperative chemotherapy. MMR status determined by preoperative biopsies may be used as a predictive biomarker to select patients for perioperative chemotherapy in curatively resectable GC.

Pattern of recurrence and overall survival in esophagogastric cancer after perioperative FLOT and clinical outcomes in MSI-H population: the PROSECCO Study

BACKGROUND

FLOT regimen is the standard perioperative treatment in Western countries for patients with locally advanced gastric (GC) or gastroesophageal junction cancer (GEJC). High microsatellite instability (MSI-H) and Mismatch Repair deficient (dMMR) demonstrated a favorable prognostic role and a concomitant negative predictive impact on the benefit of perioperative 5-fluorouracil-based doublets; however, its role in pts receiving FLOT chemotherapy is still unclear.

METHODS

This is a retrospective, multicenter observational study of 265 pts with GC/GEJC treated with perioperative FLOT regimen in 11 Italian oncology centers between January 2017 to December 2021 and analyzed for microsatellite status.

RESULTS

The MSI-H phenotype was found in 27 (10.2%) of 265 analyzed tumors. Compared to microsatellite stable (MSS) and Mismatch Repair proficient (pMMR) cases, MSI-H/dMMR were more frequently female (48.1% vs. 27.3%, p = 0.0424), elderly pts (age > 70 years, 44.4% vs. 13.4%, p = 0.0003), Laurens's intestinal type (62.5% vs. 36.1%, p = 0.02) and pts with a primary location tumor in the antrum (37 vs. 14.3%, p = 0.0004). A statistically significant difference in the rate of pathologically negative lymph node emerged (63% vs 30.7%, p = 0.0018). Compared to the MSS/pMMR tumor population, the MSI-H/dMMR subgroup had a better DFS (median not reached [NR] vs. 19.5 [15.59-23.59] mos, p = 0.031) and OS (median NR vs. 34.84 [26.68-47.60] mos, p = 0.0316).

CONCLUSIONS

These real-world data confirm that FLOT treatment is effective in daily clinical practice for locally advanced GC/GEJC, also in the MSI-H/dMMR subgroup. It also showed a higher rate of nodal status downstaging and a better outcome of MSI-H/dMMR pts in comparison to MSS/pMMR.

Gastric carcinoma with lymphoid stroma derived from hamartomatous inverted polyp with osteoclast-like giant cells: a case report

Gastric carcinomas with lymphoid stroma (GCLS) are characterized by prominent stromal infiltration of lymphocyte and account for 1-4% of gastric cancers. Although, osteoclast-like giant cells (OGC) have been reported in some GCLS, OGCs in gastric tumors is exceedingly rare. A 60-year-old woman presented to our hospital after the finding of a positive fecal blood test during a routine medical check. Esophagogastroduodenoscopy revealed a Type 0-III + IIc tumor in the middle part of the gastric body. Biopsy revealed a poorly differentiated tumor and she was referred to our department. Early phase computed tomography showed thickening of the wall in the middle of the gastric body and enlargement of nearby lymph nodes. Laparoscopic total gastrectomy was performed. Pathological examination revealed a hamartomatous inverted polyp (HIP) in the submucosal layer with tub2-por1 tumor in the HIP. Prominent lymphocytic infiltration and OGCs were found around the tumor. Immunohistochemical analysis showed that the tumor cells were negative for EBER, MLH-1, and MSH2, 6. These findings suggest that this tumor was a non-microsatellite instability (MSI)-high GCLS without Epstein-Barr virus (EBV) infection. The patient's postoperative course was uneventful and she was discharged 11 days after surgery. She remains well 3 years after surgery.

Immunotherapy in Gastro-Oesophageal Cancer: Current Practice and the Future of Personalised Therapy

Initial studies of immune checkpoint inhibitors in biomarker unselected gastro-oesophageal cancer yielded limited improvement in survival. However, emerging data from recent clinical trials suggest immunotherapies may offer a meaningful clinical benefit within selected populations. Gastro-oesophageal cancer is a heterogeneous disease with respect to histopathological and molecular features; hypermutation and the biology of immune checkpoint pathways are key to appropriate selection of populations most likely to benefit from immune checkpoint inhibitors. Programmed death-ligand 1 expression, typically measured using the combined positive score, is an important biomarker in determining which patients may benefit from immunotherapy agents. However, combined positive score thresholds are not standardised across trials and the benefit in programmed death-ligand 1-negative cohorts is uncertain. Data suggest that patients with tumours with microsatellite instability, high tumour mutational burden and Epstein-Barr Virus positivity are more likely to benefit from immunotherapy, which may be of importance within programmed death-ligand 1-negative populations. Here, we describe the current evidence base for the use of checkpoint inhibitors in the treatment of advanced gastro-oesophageal cancer and adjuvant treatment of high-risk oesophageal cancer, as well as the ongoing studies of immunotherapy in the treatment of patients with gastro-oesophageal cancers across an increasing range of clinical settings.

The Impact of Mismatch Repair Status on Prognosis of Patients With Gastric Cancer: A Multicenter Analysis

BACKGROUND

The clinical role of deficient DNA mismatch repair (dMMR)/microsatellite instability-high (MSI-H) in gastric cancer (GC) is still controversial. We aimed to analyze the relationship between dMMR/MSI-H and clinicopathological features along with survival.

METHODS

Patients who were diagnosed with GC at the three big cancer centers in China from 2015 to 2020 were evaluated retrospectively. MMR/MSI status was assessed using immunohistochemistry/PCR. Clinical and pathological data were collected from the medical record system.

RESULTS

A total of 196 patients with dMMR/MSI-H status were enrolled for analysis. The prevalence of MSI-H/dMMR in GC was 6.6%. Another 694 proficient MMR (pMMR) GC patients were enrolled for comparison. Compared with pMMR patients, dMMR/MSI-H patients were associated with older age, female predominance, distal location in the stomach, earlier TNM stage, intestinal subtype, better differentiation, and more negative HER2 status. The median overall survival (OS) of the dMMR/MSI-H group was better than that of the pMMR/microsatellite stability (MSS) group (not reached vs. 53.9 months, p = 0.014). Adjuvant chemotherapy had no impact in both disease-free survival (DFS) and OS of dMMR/MSI-H patients (p = 0.135 and 0.818, respectively). dMMR/MSI-H patients had poorer response and progression-free survival (PFS) of first-line chemotherapy, though they were statistically significant (p = 0.361 and 0.124, respectively).

CONCLUSIONS

dMMR/MSI-H GC patients have specific clinicopathological characteristics and better prognosis than pMMR patients.

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.

Pretreatment neutrophil-to-lymphocyte ratio predicts the benefit of gastric cancer patients with systemic therapy

Pretreatment neutrophil-to-lymphocyte ratio (NLR) has been reported to be associated with the prognosis of inoperable gastric cancer patients with systemic therapy. However, no consensus on the association has been reached. In this study, we mainly evaluated whether pretreatment NLR predicted the benefit of inoperable gastric cancer patients with systemic therapy, including chemotherapy, targeted therapy and immunotherapy. PubMed, Embase and Cochrane Library databases were systematically searched from inception up to September 16th, 2020. A total of 36 studies including 8614 patients were involved in the meta-analysis. Pooled data revealed that high pretreatment NLR was significantly associated with poor outcomes of OS (HR = 1.78, 95% CI = [1.59, 1.99]) and PFS (HR = 1.63, 95% CI = [1.39, 1.91]) in gastric cancer. Subgroup analyses stratified by country, study type, case load, analysis of HR, cutoff of pretreatment NLR, or treatment types arrived at the same conclusion. Pooled data based on different effect models and sensitivity analyses did not change the conclusion. Overall, high pretreatment NLR predicts the poor prognosis of inoperable gastric cancer patients with systemic therapy. Measurement of pretreatment NLR will assist clinicians with patient counseling and clinical treatment guiding accordingly.

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.

Harnessing biomarkers of response to improve therapy selection in esophago-gastric adenocarcinoma

Advanced esophago-gastric (OG) adenocarcinomas have a high mortality rate and new therapeutic options are urgently required. Despite recent advances in understanding the molecular characteristics of OG cancers, tumor heterogeneity poses a challenge in developing new therapeutics capable of improving patient outcomes. Consequently, chemotherapy remains the mainstay of systemic treatment, with the HER2 being the only predictive biomarker routinely targeted in clinical practice. Recent data indicate that immunotherapy will be incorporated into first-line chemotherapy, but further research is required to refine patient selection. This review will summarize the clinical strategies being evaluated to utilize our knowledge of predictive biomarkers with reference to novel therapeutics, and discuss the barriers to implementing precision oncology in OG adenocarcinoma.

A study of the immune infiltrate and patient outcomes in esophageal cancer

OBJECTIVES

Cancer patient outcomes and selection for novel therapies are heavily influenced by the immune contexture of the tumor microenvironment. Esophageal cancer is associated with poor outcomes. In contrast to colorectal cancer, where the immunoscore is increasingly used in prognostic staging, little is known about the immune cell populations in esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (SCC), and their clinical significance.

METHODS

Tissue microarrays were constructed from resected tumor tissue of 72 EAC patients and 23 SCC patients. Immunohistochemical staining of CD3, CD8, CD56, CD68, CD45RO, CD69, IFN-γ, IL-10, IL-4, IL-17, TGF-β, FOXP3 and CD107a was performed. Positivity was examined in both the stromal and epithelial compartments. Statistical analysis was performed to identify differences in immune cell infiltration and functional phenotypes between cancer subtypes and tissue compartments.

RESULTS

This study identified that esophageal tumors are enriched with CD45RO+ and CD8+ cells and such positivity is significantly higher in SCC compared with EAC. Furthermore, the expression of CD45RO positively correlates with that of CD8 within the tumors of both patient cohorts, suggesting a dominance of memory cytotoxic T cells. This is supported by strong positivity of degranulation marker CD107a in the stromal compartment of EAC and SCC tumors. Cytokine staining revealed a mixed pro- and anti-inflammatory profile within EAC tumors.

CONCLUSIONS

Esophageal tumors are enriched with memory cytotoxic T cells. Applying these measurements to a larger cohort will ascertain the clinical utility of assessing specific lymphocyte infiltrates in EAC and SCC tumors with regards to future immunotherapy use, patient prognosis and outcomes.

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.

Microsatellite instability in Gastric Cancer: Between lights and shadows

Gastric cancer (GC) represents an important contributor to the global burden of cancer, being one of the most common and deadly malignancies worldwide. According to TCGA and ACRG classifications, the microsatellite instable (MSI) group represents a significant subset of GCs and is currently in the limelight of many researches due to its favorable survival outcome in resectable stages compared to microsatellite stable tumors. MSI GCs hypermutated phenotype triggers immunosurveillance, making this molecular subgroup a promising candidate for immune checkpoint inhibitors treatment. Conversely, conflicting outcomes have been reported in chemotherapy settings. Due to the clinical relevance of these observations, in this review we report and discuss the molecular, pathological, prognostic, and predictive features of MSI gastric tumors.

SITC cancer immunotherapy resource document: a compass in the land of biomarker discovery

Since the publication of the Society for Immunotherapy of Cancer's (SITC) original cancer immunotherapy biomarkers resource document, there have been remarkable breakthroughs in cancer immunotherapy, in particular the development and approval of immune checkpoint inhibitors, engineered cellular therapies, and tumor vaccines to unleash antitumor immune activity. The most notable feature of these breakthroughs is the achievement of durable clinical responses in some patients, enabling long-term survival. These durable responses have been noted in tumor types that were not previously considered immunotherapy-sensitive, suggesting that all patients with cancer may have the potential to benefit from immunotherapy. However, a persistent challenge in the field is the fact that only a minority of patients respond to immunotherapy, especially those therapies that rely on endogenous immune activation such as checkpoint inhibitors and vaccination due to the complex and heterogeneous immune escape mechanisms which can develop in each patient. Therefore, the development of robust biomarkers for each immunotherapy strategy, enabling rational patient selection and the design of precise combination therapies, is key for the continued success and improvement of immunotherapy. In this document, we summarize and update established biomarkers, guidelines, and regulatory considerations for clinical immune biomarker development, discuss well-known and novel technologies for biomarker discovery and validation, and provide tools and resources that can be used by the biomarker research community to facilitate the continued development of immuno-oncology and aid in the goal of durable responses in all patients.

Prophylactic chemotherapeutic hyperthermic intraperitoneal perfusion reduces peritoneal metastasis in gastric cancer: a retrospective clinical study

Background

Peritoneal metastasis is the most frequent failure in gastric cancer. This study evaluated the role of prophylactic chemotherapeutic hyperthermic intraperitoneal perfusion (CHIP) in patients after D2 dissection.

Methods

Gastric cancer patients after D2 dissection were enrolled in this study. Patients received either chemotherapy (IV group) or CHIP (CHIP group). Sites of recurrence or metastasis, disease-free survival (DFS), overall survival (OS) and adverse events were evaluated.

Results

Twenty-two patients received CHIP treatment, and 21 patients received chemotherapy alone. The median DFS time was 24.5 and 36.5 months in the IV group and CHIP group (P = 0.044), respectively. The median OS time was 33.1 months in the IV group and not reached in the CHIP group (P = 0.037). We also found that CHIP could reduce the total recurrence/metastasis rate, especially that of peritoneal metastasis. In the subgroup analysis, DFS and OS were both superior in deficient mismatch repair (dMMR) patients than in proficient MMR (pMMR) patients.

Conclusion

This hypothesis-generating study indicates that CHIP might be feasible for gastric cancer patients after D2 resection.

Role of Immunotherapy in Advanced Gastroesophageal Cancer

PURPOSE OF REVIEW

Immunotherapy and tumor microenvironment have been at the forefront of cancer research over the past several decades. Here, we will review the role of immunotherapy in advanced gastroesophageal cancers including targeted antibodies, immunomodulating agents, vaccines, oncolytic virus therapy, and adoptive immunotherapy, and discuss the future direction for immunotherapy in this population.

RECENT FINDINGS

Targeted antibodies are already standard-of-care. An anti-PD-1 monoclonal antibody is currently FDA approved for second-line treatment of locally advanced or metastatic ESCC, as well as beyond second-line treatment of advanced G/GEJ cancers, and recent data suggests it may be considered in first-line treatment of advanced G/GEJ cancers. Combination therapies such as immunotherapy plus chemotherapy and/or radiotherapy, vaccines, oncolytic viral therapy, and adoptive immunotherapy in varying combinations are currently under active investigation. Several trials are ongoing and are hoped to reach more efficacious and individualized treatment options in advanced gastroesophageal cancer, where novel treatment options are desperately needed.

From Interconnection between Genes and Microenvironment to Novel Immunotherapeutic Approaches in Upper Gastro-Intestinal Cancers-A Multidisciplinary Perspective

Despite the progress during the last decade, patients with advanced gastric and esophageal cancers still have poor prognosis. Finding optimal therapeutic strategies represents an unmet need in this field. Several prognostic and predictive factors have been evaluated and may guide clinicians in choosing a tailored treatment. Data from large studies investigating the role of immunotherapy in gastrointestinal cancers are promising but further investigations are necessary to better select those patients who can mostly benefit from these novel therapies. This review will focus on the treatment of metastatic esophageal and gastric cancer. We will review the standard of care and the role of novel therapies such as immunotherapies and CAR-T. Moreover, we will focus on the analysis of potential predictive biomarkers such as Modify as: Microsatellite Instability (MSI) and PD-L1, which may lead to treatment personalization and improved treatment outcomes. A multidisciplinary point of view is mandatory to generate an integrated approach to properly exploit these novel antiproliferative agents.

A Molecular Stratification of Chilean Gastric Cancer Patients with Potential Clinical Applicability

Gastric cancer (GC) is a complex and heterogeneous disease. In recent decades, The Cancer Genome Atlas (TCGA) and the Asian Cancer Research Group (ACRG) defined GC molecular subtypes. Unfortunately, these systems require high-cost and complex techniques and consequently their impact in the clinic has remained limited. Additionally, most of these studies are based on European, Asian, or North American GC cohorts. Herein, we report a molecular classification of Chilean GC patients into five subtypes, based on immunohistochemical (IHC) and in situ hybridization (ISH) methods. These were Epstein-Barr virus positive (EBV+), mismatch repair-deficient (MMR-D), epithelial to mesenchymal transition (EMT)-like, and accumulated (p53+) or undetected p53 (p53-). Given its lower costs this system has the potential for clinical applicability. Our results confirm relevant molecular alterations previously reported by TCGA and ACRG. We confirm EBV+ and MMR-D patients had the best prognosis and could be candidates for immunotherapy. Conversely, EMT-like displayed the poorest prognosis; our data suggest FGFR2 or KRAS could serve as potential actionable targets for these patients. Finally, we propose a low-cost step-by-step stratification system for GC patients. To the best of our knowledge, this is the first Latin American report on a molecular classification for GC. Pending further validation, this stratification system could be implemented into the routine clinic.

Transcriptomic profiling reveals three molecular phenotypes of adenocarcinoma at the gastroesophageal junction

Cancers occurring at the gastroesophageal junction (GEJ) are classified as predominantly esophageal or gastric, which is often difficult to decipher. We hypothesized that the transcriptomic profile might reveal molecular subgroups which could help to define the tumor origin and behavior beyond anatomical location. The gene expression profiles of 107 treatment-naïve, intestinal type, gastroesophageal adenocarcinomas were assessed by the Illumina-HTv4.0 beadchip. Differential gene expression (limma), unsupervised subgroup assignment (mclust) and pathway analysis (gage) were undertaken in R statistical computing and results were related to demographic and clinical parameters. Unsupervised assignment of the gene expression profiles revealed three distinct molecular subgroups, which were not associated with anatomical location, tumor stage or grade (p > 0.05). Group 1 was enriched for pathways involved in cell turnover, Group 2 was enriched for metabolic processes and Group 3 for immune-response pathways. Patients in group 1 showed the worst overall survival (p = 0.019). Key genes for the three subtypes were confirmed by immunohistochemistry. The newly defined intrinsic subtypes were analyzed in four independent datasets of gastric and esophageal adenocarcinomas with transcriptomic data available (RNAseq data: OCCAMS cohort, n = 158; gene expression arrays: Belfast, n = 63; Singapore, n = 191; Asian Cancer Research Group, n = 300). The subgroups were represented in the independent cohorts and pooled analysis confirmed the prognostic effect of the new subtypes. In conclusion, adenocarcinomas at the GEJ comprise three distinct molecular phenotypes which do not reflect anatomical location but rather inform our understanding of the key pathways expressed.

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.

Tumor immune response and immunotherapy in gastric cancer

Remarkable developments in immuno-oncology have changed the landscape of gastric cancer (GC) treatment. Because immunotherapy intervenes with tumor immune response rather than directly targeting tumor cells, it is important to develop a greater understanding of tumor immunity. This review paper summarizes the tumor immune reaction and immune escape mechanisms while focusing on the role of T cells and their co-inhibitory signals, such as the immune checkpoint molecules programmed death-1 and programmed deathligand 1 (PD-L1). This paper also describes past clinical trials of immunotherapy for patients with GC and details their clinical implications. Strong predictive markers are essential to improve response to immunotherapy. Microsatellite instability, Epstein-Barr virus, PD-L1 expression, and tumor mutational burden are now regarded as potent predictive markers for immunotherapy in patients with GC. Novel immunotherapy and combination therapy targeting new immune checkpoint molecules such as lymphocyte-activation gene 3, T cell immunoglobulin, and mucin domain containing-3, and indoleamine 2,3-dioxygenase have been suggested, and trials are ongoing to evaluate their safety and efficacy. Immunotherapy is an important treatment option for patients with GC and has great potential for improving patient outcome, and further research in immuno-oncology should be carried out.

Loss of Tyrosine Phosphatase Delta Promotes Gastric Cancer Progression via Signal Transducer and Activator of Transcription 3 Pathways

BACKGROUND

The protein tyrosine phosphatase delta (PTPRD) is a tumor suppressor, and its role in gastric cancer (GC) remains poorly understood.

METHODS

The expressions of PTPRD were determined based on public data. In addition, the mRNA expressions of PTPRD in the GC samples, and the expressions of PTPRD in the GC cell lines including HGC27, SGC790, and BGC823, and gastric epithelial cell line GES-1 were determined by western blotting and quantitative real-time PCR. Furthermore, PTPRD siRNA was transfected into the HGC27 cell line, and then, cell proliferation, migration, and invasion were evaluated. The activity of signal transducer and activator of transcription 3 (STAT3) pathways in HGC27 cells transfected with PTPRD siRNA was determined by western blotting.

RESULTS

PTPRD deletion was found in the GC patients, and this deletion was found to be correlated with poor prognosis in the GC patients. Expression of PTPRD was significantly downregulated in gastric carcinoma specimens and tumor cell lines when compared with those in normal controls. PTPRD also plays a key role in the GC cells proliferation, invasion, and migration. Silencing PTPRD expression by siRNA dramatically promoted GC cells proliferation, invasion, and migration. Mechanism study demonstrated that phosphorylation of STAT3 was inhibited by silencing PTPRD expression and the according changes including inhibition of cell migration and invasion were observed.

CONCLUSION

This study supports PTPRD as a tumor suppressor and could be served as a marker for prognostic of GC. Silencing PTPRD could be a potential therapeutic in GC.

High Proportion of Potential Candidates for Immunotherapy in a Chilean Cohort of Gastric Cancer Patients: Results of the FORCE1 Study

Gastric cancer (GC) is a heterogeneous disease. This heterogeneity applies not only to morphological and phenotypic features but also to geographical variations in incidence and mortality rates. As Chile has one of the highest mortality rates within South America, we sought to define a molecular profile of Chilean GCs (ClinicalTrials.gov identifier: NCT03158571/(FORCE1)). Solid tumor samples and clinical data were obtained from 224 patients, with subsets analyzed by tissue microarray (TMA; n = 90) and next generation sequencing (NGS; n = 101). Most demographic and clinical data were in line with previous reports. TMA data indicated that 60% of patients displayed potentially actionable alterations. Furthermore, 20.5% were categorized as having a high tumor mutational burden, and 13% possessed micro-satellite instability (MSI). Results also confirmed previous studies reporting high Epstein-Barr virus (EBV) positivity (13%) in Chilean-derived GC samples suggesting a high proportion of patients could benefit from immunotherapy. As expected, TP53 and PIK3CA were the most frequently altered genes. However, NGS demonstrated the presence of TP53, NRAS, and BRAF variants previously unreported in current GC databases. Finally, using the Kendall method, we report a significant correlation between EBV+ status and programmed death ligand-1 (PDL1)+ and an inverse correlation between p53 mutational status and MSI. Our results suggest that in this Chilean cohort, a high proportion of patients are potential candidates for immunotherapy treatment. To the best of our knowledge, this study is the first in South America to assess the prevalence of actionable targets and to examine a molecular profile of GC patients.

Off-label use of common predictive biomarkers in gastrointestinal malignancies: a critical appraisal

The use of immunohistochemistry (IHC) as a companion diagnostic is an increasingly important part of the case workup by pathologists and is often central to clinical decision making. New predictive molecular markers are constantly sought for to improve treatment stratification parallel to drug development. Unfortunately, official biomarker guidelines lag behind, and pathologists are often left hesitating when medical oncologists request off-labelled biomarker testing. We performed a literature review of five commonly requested off-label IHC predictive biomarkers in gastrointestinal tract (GIT) malignancies: HER2, mismatch repair (MMR), PD-L1, BRAF V600E and ROS1. We found that HER2 amplification is rare and poorly associated to IHC overexpression in extracolonic and extragastric GIT cancers; however in KRAS wild type colorectal cancers, which fail conventional treatment, HER2 IHC may be useful and should be considered. For MMR testing, more evidence is needed to recommend reflex testing in GIT cancers for treatment purposes. MMR testing should not be discouraged in patients considered for second line checkpoint inhibitor therapy. With the exception of gastric tumors, PD-L1 IHC is a weak predictor of checkpoint inhibitor response in the GIT and should be replaced by MMR in this context. BRAF inhibitors showed activity in BRAF V600E mutated cholangiocarcinomas and pancreatic carcinomas in non-first line settings. ROS1 translocation is extremely rare and poorly correlated to ROS1 IHC expression in the GIT; currently there is no role for ROS1 IHC testing in GIT cancers. Overall, the predictive biomarker literature has grown exponentially, and official guidelines need to be updated more regularly to support pathologists’ testing decisions.

Identification of genomic features associated with immunotherapy response in gastrointestinal cancers

Gastrointestinal (GI) cancers prevail and account for an extremely high number of cancer deaths worldwide. The traditional treatment strategies, including surgery, chemotherapy, radiotherapy, and targeted therapy, have a limited therapeutic effect for advanced GI cancers. Recently, immunotherapy has shown promise in treating various refractory malignancies, including the GI cancers with mismatch repair deficiency (dMMR) or microsatellite instability (MSI). Thus, immunotherapy could be a promising treatment approach for GI cancers. Unfortunately, only a small proportion of GI cancer patients currently respond to immunotherapy. Therefore, it is important to discover predictive biomarkers for stratifying GI cancer patients response to immunotherapy. Certain genomic features, such as dMMR/MSI, tumor mutation burden (TMB), and tumor aneuploidy have been associated with tumor immunity and im-munotherapy response and may serve as predictive biomarkers for cancer immunotherapy. In this review, we examined the correlations between tumor immunity and three genomic features: dMMR/MSI, TMB, and tumor aneuploidy. We also explored their correlations using The Cancer Genome Atlas data and confirmed that the dMMR/MSI status, high TMB, and low tumor aneuploidy are associated with elevated tumor immunity in GI cancers. To improve the immunotherapeutic potential in GI cancers, more genetic or genomic features associated with tumor immune response need to be identified. Furthermore, it is worth exploring the combination of different immunotherapeutic methods and the combination of immunotherapy with other therapeutic approaches for cancer therapy.

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.

Prognostic Utility of Tumor-Infiltrating Lymphocytes in Noncolorectal Gastrointestinal Malignancies

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) and mismatch repair gene mutation (MMR) status are emerging biomarkers in immunotherapy. MMR status and TILs have significant clinical implications with regard to treatment with checkpoint inhibitors. We designed a study to determine the frequency and prognostic utility of TILs and MMR in advanced unresectable noncolorectal gastrointestinal (NCGI) malignancies.

METHODS

This is a retrospective cohort study of patients who were diagnosed with advanced noncolorectal gastrointestinal tumors. Biopsy specimens were tested for MMR status by immunohistochemistry along with evaluation of TILs. Kaplan-Meier analysis was performed to determine the impact of TILS and MMR on survival.

RESULTS

We analyzed 146 patients; the mean age at diagnosis was 66.4 ± 11.2 years. 65.8% patients were male, and 62.3% patients had stage 4 disease. All cases had proficient MMR status. The percentage of patients with TILs >5 was 50.7%. There was no statistically significant difference in median overall survival (OS) by TILs when stratified by stage of tumor. When stratified by type of tumor, median OS by TILs level was significantly different for hepatocellular cancers (⩽5 TILs, 86 days versus >5 TILs 312 days, P = .031).

CONCLUSIONS

Our study suggests that MMR-deficient tumors are quite rare in advanced NCGI malignancies. More than 5 TILs per high power field, evaluated simply on a routine hematoxylin and eosin-stained glass slide confer a better prognosis to most noncolorectal gastrointestinal malignancies, especially hepatocellular carcinoma. This has immense clinical utility with regard to eligibility for immunotherapy.

Emerging Therapies in the Management of Advanced-Stage Gastric Cancer

Globally, gastric malignancy contributes to significant cancer-related morbidity and mortality. Despite a recent approval of two targeted agents, trastuzumab and ramucirumab, the treatment options for advanced-stage gastric cancer are limited. Consequently, the overall clinical outcomes for patients with advanced-stage gastric cancer remain poor. Numerous agents that are active against novel targets have been evaluated in the course of randomized trials; however, most have produced disappointing results because of the molecular heterogeneity of gastric cancer. The Cancer Genome Atlas (TCGA) project proposed a new classification system for gastric cancer that includes four different tumor subtypes based on molecular characteristics. This change led to the identification of several distinct and potentially targetable pathways. However, most agents targeting these pathways do not elicit any meaningful clinical benefit when employed for the treatment of advanced-stage gastric cancer. Most advanced-stage gastric cancer trials currently focus on agents that modulate tumor microenvironments and cancer cell stemness. In this review, we summarize data regarding novel compounds that have shown efficacy in early phase studies and show promise as effective therapeutic agents, with special emphasis on those for which phase III trials are either planned or underway.

The evolving immunotherapeutic landscape in advanced oesophagogastric cancer

Improvements in median overall survival in the advanced oesophagogastric (OG) setting have plateaued, underlining the need for improved therapeutic approaches in this patient population. Immunotherapeutics are inducing unexpected durable responses in an expanding list of advanced disease indications. Although OG cancers have traditionally been considered to be more challenging to treat with immunotherapy than some other malignancies because of their variable tumour mutational burden and relative scarcity of infiltrating T cells, immune checkpoint inhibitor (ICPI) trials conducted over the last few years suggest there is an important role for these treatments. ICPI efficacy may be demonstrated in specific molecular subtypes of OG cancer. This review outlines the improvements in defining predictive biomarkers of responsiveness to ICPIs. Increasingly, identification of an expanding list of ICPI resistance mechanisms will drive biomarker-directed research. In addition, the specific rationale to combine ICPIs with chemotherapies, radiotherapies, targeted therapies and other novel immunotherapeutic drugs will be discussed.

Association between density of tumor-infiltrating lymphocytes and prognoses of patients with gastric cancer

INTRODUCTION

Tumor-infiltrating lymphocytes (TILs) have been shown to be of prognostic significance in patients with gastric cancer. This study aims to investigate the association between density of TILs and prognoses of patients with gastric cancer.

METHODS

The relative studies of tumor-infiltrating lymphocytes in tumor tissue from patients with gastric cancer were systematically searched from PubMed and Embase until October 31, 2017. The pooled hazard ratios (HRs) and their 95% confidence intervals (95%CI) for overall survival (OS) were estimated.

RESULTS

Twenty-nine studies involving 4,942 patients were included into analyses. Subset of TILs included CD8, CD3, CD4, and FOXP3 T cell density. Results from meta-analyses revealed that high density of intratumoral CD8 T cells (HR = 0.77, 95% CI 0.63-0.95) and CD3 (HR = 0.62, 95% CI 0.49-0.77) were associated with significantly higher OS than those with low density in patients with gastric cancer. Moreover, a larger number of general TILs density also suggested a favorable prognosis (HR 0.75, 95% CI 0.67-0.84). However, patients with high density of intratumoral FOXP3 T or CD4 T cells were not statistically associated with higher or lower OS than those with low density (HR 1.41, 95% CI 0.97-2.05; HR = 0.86, 95% CI 0.47-1.57). Sample size and follow-up period seemed to influence study outcomes.

CONCLUSION

The present study revealed that high density of intratumoral CD8 and CD3 T cells were associated with better OS in patients with gastric cancer.

Optimal management of resected gastric cancer

Although advances in medical treatment for gastric cancer (GC) have been made, surgery remains the mainstay of cure for patients with localized disease. Improvement in surgical modalities leads to increased chance of cure for resected patients, but a non-negligible number of patients eventually relapse. On this basis, it has been hypothesized that the addition of complementary systemic or local treatments (such as chemotherapy and radiotherapy) could help in improving patients' survival by reducing the risk of recurrence. Several studies have tried to identify the best approach in localized GC: some of them have assessed the role of perioperative chemotherapy [CT] with different drug combinations, while others have focused on the benefit obtained by addition of radiotherapy, whose role is still under investigation. In particular, the role of chemoradiotherapy, both in adjuvant and neoadjuvant settings, is still uncertain. In the last few years, several clinicopathological and molecular factors have been investigated and identified as potential prognostic markers in GC. Many of these factors could have influenced the outcome of patients receiving combined treatments in the abovementioned studies. Patients have not been generally distinguished by the site of disease (esophageal, gastric and junctional cancers) and surgical approach, making data difficult to be interpreted. The purpose of this review was to shed light on these highly controversial topics.

Combined neutrophil/platelet/lymphocyte/differentiation score predicts chemosensitivity in advanced gastric cancer

Background

Gastric cancer is common in developing regions, and we hope to find out an economical but practical prognostic indicator. It was reported that pre-treatment peripheral neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), as well as differentiation status, were associated with cancer progression. Hence, we introduced a novel combined Neutrophil/platelet/lymphocyte/differentiation Score (cNPLDS) to improve the prediction value of palliative chemotherapeutic response in advanced gastric cancer.

Methods

According to statistical sample size estimation, 136 primary diagnosed unresectable advanced ptaients were included for a retrospective study. The follow-up end-point was progression free survival (PFS) during the first-line palliative chemotherapy. Differentiation stratified patients into well, medium and poor groups by score 1 to 3, while patients with neither elevated NLR and PLR, only one elevated, or both elevated were of the combined NLR-PLR score (cNPS) 1 to 3, respectively. The cNPLDS was calculated by multiplying the tumor differentiation score and cNPS.

Results

Determined by the receiver operating characteristic (ROC) curve, the optimal cut-off points for NLR and PLR were 3.04 and 223. Through univariate analysis and survival analysis, poor differentiation, high NLR, high PLR, high cNPS, and high cNPLDS respectively indicated inferior PFS during the first-line palliative chemotherapy. Patients were furhter classified into low to high risk groups by cNPLDS. Groups of elevated NLR, PLR, cNPS, and cNPLDS showed lower disease control rate. Compared to other parameters, cNPLDS significantly improved the accuracy in predicing the first-progression.

Conclusions

This study indicates that the novel parameter cNPLDS is superior to NLR or PLR alone, or even cNPS, in predicting the first-line chemosensitivity in advanced gastric cancer.

Gene expression profiles for a prognostic immunoscore in gastric cancer

Background

Increasing evidence has indicated an association between immune infiltration in gastric cancer and clinical outcome. However, reliable prognostic signatures, based on systematic assessments of the immune landscape inferred from bulk tumour transcriptomes, have not been established. The aim was to develop an immune signature, based on the cellular composition of the immune infiltrate inferred from bulk tumour transcriptomes, to improve the prognostic predictions of gastric cancer.

Methods

Twenty‐two types of immune cell fraction were estimated based on large public gastric cancer cohorts from the Gene Expression Omnibus using CIBERSORT. An immunoscore based on the fraction of immune cell types was then constructed using a least absolute shrinkage and selection operator (LASSO) Cox regression model.

Results

Using the LASSO model, an immunoscore was established consisting of 11 types of immune cell fraction. In the training cohort (490 patients), significant differences were found between high‐ and low‐immunoscore groups in overall survival across and within subpopulations with an identical TNM stage. Multivariable analysis revealed that the immunoscore was an independent prognostic factor (hazard ratio 1·92, 95 per cent c.i. 1·54 to 2·40). The prognostic value of the immunoscore was also confirmed in the validation (210) and entire (700) cohorts.

Conclusion

The proposed immunoscore represents a promising signature for estimating overall survival in patients with gastric cancer.

Immunoscore predicts prognosis

Neutrophil-to-lymphocyte ratio as prognostic indicator in gastrointestinal cancers: a systematic review and meta-analysis

An accurate, time efficient, and inexpensive prognostic indicator is needed to reduce cost and assist with clinical decision making for cancer management. The neutrophil-to-lymphocyte ratio (NLR), which is derived from common serum testing, has been explored in a variety of cancers. We sought to determine its prognostic value in gastrointestinal cancers and performed a meta-analysis of published studies using the Meta-analysis Of Observational Studies in Epidemiology guidelines. Included were randomized control trials and observational studies that analyzed humans with gastrointestinal cancers that included NLR and hazard ratios (HR) with overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), and/or cancer-specific survival (CSS).

We analyzed 144 studies comprising 45,905 patients, two-thirds of which were published after 2014. The mean, median, and mode cutoffs for NLR reporting OS from multivariate models were 3.4, 3.0, 5.0 (±IQR 2.5-5.0), respectively. Overall, NLR greater than the cutoff was associated with a HR for OS of 1.63 (95% CI, 1.53-1.73; P < 0.001). This association was observed in all subgroups based on tumor site, stage, and geographic region. HR for elevated NLR for DFS, PFS, and CSS were 1.70 (95% CI, 1.52-1.91, P < 0.001), 1.64 (95% CI, 1.36-1.97, P < 0.001), and 1.83 (95% CI, 1.50-2.23, P < 0.001), respectively.

Available evidence suggests that NLR greater than the cutoff reduces OS, independent of geographic location, gastrointestinal cancer type, or stage of cancer. Furthermore, DFS, PFS, and CSS also have worse outcomes with elevated NLR.

Hypermutation and microsatellite instability in gastrointestinal cancers

Recent progress in cancer genome analysis using next-generation sequencing has revealed a high mutation burden in some tumors. The particularly high rate of somatic mutation in these tumors correlates with the generation of neo-antigens capable of eliciting an immune response. Identification of hypermutated tumors is therefore clinically valuable for selecting patients suitable for immunotherapy treatment. There are several known causes of hypermutation in tumors, such as ultraviolet light in melanoma, tobacco smoke in lung cancer, and excessive APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like) activity in breast and gastric cancer. In gastrointestinal cancers, one of the leading causes of hypermutation is a defect in DNA mismatch repair, which results in microsatellite instability (MSI). This review will focus on the frequency, characteristics and genomic signature of hypermutated gastrointestinal cancers with MSI. Detection of tumor hypermutation in cancer is expected to not only predict the clinical benefit of immune checkpoint inhibitor treatment, but also to provide better surgical strategies for the patients with hypermutated tumors. Thus, in an era of precision medicine, identification of hypermutation and MSI will play an important role directing surgical and chemotherapeutic treatment.

Emerging biomarkers for immunomodulatory cancer treatment of upper gastrointestinal, pancreatic and hepatic cancers

Carcinomas of the oesophagus, stomach, pancreas and liver are common and account for a disproportionately high number of cancer deaths. There is a need for new treatment options for patients with advanced disease. Immunomodulatory treatments including immune checkpoint blockade offer a promising new approach, with efficacy shown in other solid tumour types. However, only a small proportion of patients with carcinomas of the oesophagus, stomach, pancreas and liver have responded to single agent checkpoint inhibitors, and there is a need for markers that are predictive of response to guide treatment of individual patients. Predictive markers may include epidemiological factors such as ethnicity, the genomic status of the tumour, circulating markers, expression of immune checkpoint molecules, and other features of the stromal/immune response at the site of the tumour. This review will focus on predictive biomarkers for immune checkpoint blockade in oesophageal, gastric, pancreatic and hepatocellular carcinomas, including the genomic context and immune landscape in which they occur. Pancreatic carcinomas are largely resistant to immune checkpoint inhibition in trials to date, therefore emerging immunomodulatory treatments in this tumour type are also reviewed.

Immunotherapy for Esophageal and Gastric Cancer

PD-L1 upregulation occurs in approximately 40% of gastroesophageal cancers. However, unlike other solid tumors, there is minimal PD-L1 expressed on the cancer cells; rather, expression occurs predominantly on infiltrating myeloid cells. Preliminary clinical data involving single-agent PD-1/PD-L1 inhibitors in metastatic gastroesophageal cancer have reported response rates of 22%-27% for patients with PD-L1⁺ tumors and 10%-17% for unselected patients. The phase III ONO-4538-12 (ATTRACTION 2) trial has demonstrated an improved overall survival for nivolumab compared with placebo for patients with heavily pretreated gastric cancer. In the future, we will need better biomarkers to select those most likely to respond and/or identify patients who may need combination immunotherapeutics or alternate strategies. A number of subsets of gastric cancer with different immune signatures, most notably tumors positive for Epstein-Barr virus and microsatellite instability, have been identified, with approximately 50% and 94% PD-L1⁺ staining seen on tumor cells and immune cells in the EBV subtype and approximately 33% and 45% PD-L1⁺ staining seen on tumor cells and immune cells in MSI high tumors. Both subtypes demonstrate PD-L1⁺ immune cells with tumor-infiltrating patterns, unlike the more commonly seen PD-L1⁺ immune cells at the invasive margin. PD-L2 expression has been reported in 52% of esophageal adenocarcinomas but little is known about the expression of other immune checkpoints. Additional factors that suggest gastroesophageal cancers may respond to checkpoint inhibition include the high somatic mutation burden and the link with chronic inflammation. Here we provide a comprehensive review of the checkpoint inhibitor data published to date in advanced esophagogastric cancers and rationalize how the immune microenvironment in these diverse tumors can explain response or resistance to immunotherapeutics.

Pembrolizumab for treatment of advanced gastric and gastroesophageal junction adenocarcinoma

Pembrolizumab is a monoclonal antibody directed against PD-1 that is US FDA approved for treatment of advanced PD-L1 positive gastric and gastroesophageal junction adenocarcinoma in patients who have progressed on at least two prior lines of chemotherapy. This article summarizes the clinical evidence regarding safety, tolerability and efficacy of pembrolizumab in this setting. In addition, this article describes the investigational use of pembrolizumab as first- and second-line therapy and in combination with other treatments. Finally, this review compares other checkpoint inhibitors to pembrolizumab for the treatment of this disease, and explores predictive biomarkers of response to PD-1 blockade.