Clinicopathologic implications of immune classification by PD-L1 expression and CD8-positive tumor-infiltrating lymphocytes in stage II and III gastric cancer patients

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.

Remodeling the hepatic immune microenvironment and demolishing T cell traps to enhance immunotherapy efficacy in liver metastasis

Immune checkpoint inhibitors (ICIs) exhibit compromised therapeutic efficacy in many patients with advanced cancers, particularly those with liver metastases. Much of this incapability can be ascribed as an irresponsiveness resulting from the "cold" hepatic tumor microenvironment that acts as T cell "traps" for which there currently lack countermeasures. We report a novel nanomedicine that converts the hepatic immune microenvironment to a "hot" phenotype by targeting hepatic macrophage-centric T cell elimination. Using the nanomedicine, composed of KIRA6 (an endothelium reticulum stress inhibitor), α-Tocopherol nanoemulsions, and anti-PD1 antibodies, we found its potency in murine models of orthotopic colorectal tumors and hepatic metastases, restoring immune responses and enhancing anti-tumor effects. A post-treatment scrutiny of the immune microenvironment landscape in the liver reveals repolarization of immunosuppressive hepatic macrophages, upregulation of Th1-like effector CD4+ T cells, and rejuvenation of dendritic cells along with CD8+ T cells. These findings suggest adaptations of liver-centric immune milieu modulation strategies to improve the efficacy of ICIs for a variety of "cold" tumors and their liver metastases.

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.

Immune checkpoints signature-based risk stratification for prognosis of patients with gastric cancer

Until now, few researches have comprehensive explored the role of immune checkpoints (ICIs) and tumor microenvironment (TME) in gastric cancer (GC) patients based on the genomic data. RNA-sequence data and clinical information were obtained from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD) database, GSE84437 and GSE84433. Univariate Cox analysis identified 60 ICIs with prognostic values, and these genes were then subjected to NMF cluster analysis and the GC samples (n = 804) were classified into two distinct subtypes (Cluster 1: n = 583; Cluster 2: n = 221). The Kaplan-Meier curves for OS analysis indicated that C1 predicted a poorer prognosis. The C2 subtype illustrated a relatively better prognosis and characteristics of "hot tumors," including high immune score, overexpression of immune checkpoint molecules, and enriched tumor-infiltrated immune cells, indicating that the NMF clustering in GC was robust and stable. Regarding the patient's heterogeneity, an ICI-score was constructed to quantify the ICI patterns in individual patients. Moreover, the study found that the low ICI-score group contained mostly MSI-low events, and the high ICI-score group contained predominantly MSI-high events. In addition, the ICI-score groups had good responsiveness to CTLA4 and PD-1 based on The Cancer Immunome Atlas (TCIA) database. Our research firstly constructed ICIs signature, as well as identified some hub genes in GC patients.

Programmed Death Ligand 1 (PD-L1) Expression and CD8 + Tumor-infiltrating Lymphocyte-based Tumor Immune Microenvironment Classification in Gynecologic Carcinosarcoma: Prognostic Impact and Implications for Therapy

To investigate the prevalence and prognostic significance of programmed death ligand-1 (PD-L1) expression and CD8 + tumor-infiltrating lymphocytes (TILs) in gynecologic carcinosarcoma, 81 cases (68 uterine, 12 ovarian, and 1 fallopian tube) were immunostained with PD-L1 and CD8 using tissue microarrays (3 mm core diameter) from intratumoral areas with the highest TILs. Tumor proportion score (TPS) ≥1% and combined positive score (CPS) ≥1 were considered positive for PD-L1. CD8 + TILs were counted in each core, and CD8 + TIL density (CD8TILD) was calculated. Cases were classified as CD8 Neg (<1.4/mm 2 CD8TILD), CD8 Pos (≥1.4/mm 2 CD8TILD) and CD8 HIGH (≥14/mm 2 CD8TILD) and grouped into 4 tumor immune microenvironment (TIME) groups: (1) PD-L-1 Pos /CD8 Pos , (2) PD-L1 Neg /CD8 Neg , (3) PD-L1 Pos /CD8 Neg , and (4) PD-L1 Neg /CD8 Pos . PD-L1 expression by TPS and CPS was detected in 19.8% and 39.6% cases, respectively. Kaplan-Meier curves with log-rank analysis showed that higher density of CD8 + TILs were associated with longer overall survival (OS) ( P =0.05 for CD8 Pos and P =0.014 for CD8 HIGH ), and CD8 HIGH status was associated with longer OS irrespective of tumor stage ( P =0.045, hazard ratio: 0.11, 95% confidence interval: 0.014-0.951). Thirty-three percent of patients belonged to TIME group 1. PD-L1 expression and TIME groups were not associated with OS or progression-free survival. We found that high density of CD8 + TILs is an independent indicator of better OS. In 33% cases PD-L1 expression is associated with increased CD8 + TILs ("acquired immune evasion" pattern of PD-L1 expression), hence they may benefit from anti PD-1/PD-L1 therapy. PD-L1 expression alone and TIME groups do not affect survival in gynecologic carcinosarcoma.

Prognostic role and clinical significance of tumor-infiltrating lymphocyte (TIL) and programmed death ligand 1 (PD-L1) expression in gastric cancer: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

This study intended to evaluate the prognostic effects of programmed death-ligand 1 (PD-L1) and tumor-infiltrating lymphocytes (TILs) in survival and their associations with clinicopathological characteristics in patients with gastric cancer.

METHODS

PubMed, Scopus, ProQuest, Web of Science, and Ovid databases were searched to obtain the relevant studies. Eleven studies with 2298 patients were included in this study.

RESULTS

Like the level of TILs, there were no significant associations between PD-L1 expression and TNM stage, lymph node metastasis, vascular invasion, and tumor location (All p values ≥ 0.05). Furthermore, there was no significant association between PD-L1 expression with overall survival (OS) (HR = 0.76, 95% CI: 0.55 to 1.05, p value = 0.10) and disease-free survival (DFS) (HR = 0.62, 95% CI: 0.10 to 3.68, p value = 0.59). In the assessment of TILs presence and survival association, the analysis showed no association between TILs presence and overall survival (OS) (HR = 0.95, 95% CI: 0.62 to 1.45).

CONCLUSIONS

In conclusion, the study has revealed no prognostic effect of PD-L1 and TILs in gastric cancer patients.

Prognostic Implication of EBV Infection in Gastric Carcinomas: A Systematic Review and Meta-Analysis

Background and objectives: This study aims to elucidate the prognostic implications of Epstein-Barr virus (EBV) infection in gastric carcinomas (GCs) through a systematic review and meta-analysis. Materials and Methods: In total, 57 eligible studies and 22,943 patients were included in this meta-analysis. We compared the prognoses of EBV-infected and non-infected GC patients. The subgroup analysis was performed based on the study location, molecular classification, and Lauren's classification. This study was checked according to the PRISMA 2020. The meta-analysis was performed using the Comprehensive Meta-Analysis software package. Results: EBV infection was found in 10.4% (95% confidence interval (CI) 0.082-0.131) of GC patients. The EBV-infected GC patients had a better overall survival compared with the EBV-non-infected GC patients (hazard ratio (HR) 0.890, 95% CI 0.816-0.970). In the subgroup analysis based on molecular classification, no significant differences were found between EBV+ and microsatellite instability and microsatellite stable (MSS)/EBV- subgroups (HR 1.099, 95% CI 0.885-1.364 and HR 0.954, 95% CI 0.872-1.044, respectively). In the diffuse type of Lauren's classification, EBV-infected GCs have a better prognosis compared with the EBV-non-infected GCs (HR 0.400, 95% CI 0.300-0.534). The prognostic impact of EBV infection was found in the Asian and American subgroups but not in the European subgroup (HR 0.880, 95% CI 0.782-0.991, HR 0.840, 95% CI 0.750-0.941, and HR 0.915, 95% CI 0.814-1.028). Conclusions: EBV infection is a favorable survival factor for GCs. However, the prognostic implications of EBV infection in the new molecular classification are not clear.

Histological Type, Cytotoxic T Cells and Macrophages in the Tumor Microenvironment Affect the PD-L1 Status of Gastric Cancer

Gastric cancer (GC) therapies include gastrectomy and chemoradiotherapy. The tumor immune microenvironment (TME) has implications for potential immunotherapy. We analyzed the expression of PD-L1, CD8, CTLA-4 and IFN-γ in the tumor and regional lymph node (LN) of patients with GC and compared it with clinical and pathological data. Paraffin blocks were collected from 97 patients undergoing gastrectomy/lymphadenectomy for GC. Double immunohistochemistry was performed for CD8 and PD-L1 and double immunofluorescence for CTLA-4 and IFN-γ. Statistical significance was set at p < 0.05. PD-L1 expression in tumor cells was associated with intestinal GC type (p = 0.046), the density of macrophages and CD8 + T cells (p < 0.001, both). The median number of CD8+ T cells was higher in PD-L1-positive than in -negative tumors. A cut-off of 28.5 CD8 + T cells in one high-magnification field predicted PD-L1-positive tumors (AUROC 0.797, sensitivity 74.2%, specificity 77.3%). IFN-γ expression in tumor cells was found in 37 GCs and was positively associated with CTLA4+ lymphocytes in the LN (p = 0.027) and CTLA4+/IFN-γ+ in tumors and the LN (all p < 0.001). The median overall survival (OS) was 17 months. In the group of deceased patients, IFN-γ expression in metastases correlated with lower OS (RHO = −0.314, p = 0.008). PD-L1 expression in tumor cells correlated with CD8 + T cells and macrophages in the TME and IFN-γ expression with suppressive CTLA4+/IFNγ+ immune cells in the TME and LN.

Clinicopathological features of PD-L1 protein expression, EBV positivity, and MSI status in patients with advanced gastric and esophagogastric junction adenocarcinoma in Japan

This real-world study examined the prevalence of programmed death ligand-1 (PD-L1) expression and assessed the frequency of microsatellite instability-high (MSI-H) status and Epstein-Barr virus (EBV) positivity in Japanese patients with advanced gastric and gastroesophageal junction (GEJ) adenocarcinoma. This multicenter (5 sites), retrospective, observational study (November 2018–March 2019) evaluated Japanese patients with advanced gastric and GEJ adenocarcinoma after surgical resection (Stage II/III at initial diagnosis) or unresectable advanced cancer (Stage IV). The primary objectives were prevalence of PD-L1 expression (combined positive score [CPS] ≥1), MSI status, and EBV positivity. Tumor specimens of 389/391 patients were analyzed (male, 67.1%; mean age, 67.6 ± 12.2 years); 241/389 (62%) were PD-L1 positive, 24/379 (6.3%) had MSI-H tumors, and 13/389 (3.3%) were EBV positive. PD-L1 expression was higher in tumor-infiltrating immune cells than in tumor cells for lower CPS cutoffs. Among patients with MSI-H tumors and EBV-positive tumors, 19/24 (79.2%) and 9/13 (69.2%), respectively, were PD-L1 positive. A greater proportion of patients with MSI-H tumors (83.3% [20/24]) were PD-L1 positive than those with MSI-low/stable tumors (60.8% [216/355]; p = .0297); similarly, an association was observed between history of H pylori infection and PD-L1 expression. A higher proportion of patients with MSI-H tumors demonstrated PD-L1 expression with a CPS ≥10 (66.7% [16/24]) vs those with MSI-low/stable tumors (24.8% [88/355]; p < .0001). The prevalence of PD-L1 positivity among Japanese patients was comparable to that in previous pembrolizumab clinical trials and studies in gastric cancer. Particularly, higher PD-L1 expression was observed in MSI-H tumors.

PD-L1 expression in EBV associated gastric cancer: a systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review and meta-analysis is to the summarize the evidence on programmed cell death protein ligand 1 (PD-L1) in Epstein-Barr virus associated gastric cancer (EBVaGC) and to estimate the expression rate of PD-L1 among this subtype of Gastric Cancer (GC).

MATERIALS AND METHODS

For this study, PubMed^®, EMBASE^® and Web of Science^® databases were searched for articles published until 1st November 2021. A total of 43 eligible publications with a total of 11,327 patients were included analysis based on inclusion and exclusion criteria. A total of 41 publications present data for proportion estimation and 33 for comparison of PD-L1 between EBV positive and negative GC. DerSimonian-Laird random-effects model was used for meta-analysis.

RESULTS

The analysis showed that in EBVaGC the pooled positivity rate for PD-L1 was 54.6% (p < 0.001), with a high heterogeneity between the included studies, which was associated with variation on positivity criteria for PD-L1 expression. Overall, the study reveals an increased association between PD-L1 and EBVaGC (OR = 6.36, 95% CI 3.91-10.3, p < 0.001). Furthermore, the study revealed that GC with lymphoid stroma (GCLS) is highly associated with EBV (OR = 17.4, 95% CI 6.83-44.1, p < 0.001), with a pooled EBV positivity rate of 52.9% (p < 0.001).

CONCLUSIONS

Patients with EBVaGC tend to show higher PD-L1 expression, which enhances EBV positivity as a promising marker for patient selection for immunotherapy targeted agents. A uniform criteria for PD-L1 positivity in tumor cells is needed, as well as further prospective studies to validate our findings and their prognostic significance.

Revisiting the 8th AJCC system for gastric cancer: A review on validations, nomograms, lymph nodes impact, and proposed modifications

Gastric cancer is the fifth most frequently diagnosed cancer worldwide, behind breast, lung, colorectal, and prostate cancers. In gastric cancer, multimodality treatment shows prospective benefits and also improves survival. Surgery, however, is the mainstay of curative treatment. The staging of gastric cancer patients is critical for harmonization of care. Accurate stages assure that informed clinical decisions are timely made. The American Joint Committee on Cancer (AJCC) staging system is the most widely applied system in to determine the disease's prognosis and survival prediction. The recently adopted 8th AJCC TNM staging system has been revised to enhance its survival predictive power. Subsequent studies have established the validity of the current edition, demonstrating improved stage stratification, discriminatory power, and survival prediction. However, other studies have cast doubt on the superiority of the new edition. Innovations aimed at further improving its prognosis have resulted in developing of novel models. Advances in our understanding of the tumor microenvironment and molecular categorization of cancer have resulted in proposals for their inclusion in TNM staging as potential complementary factors that enhance survival prediction and prognostic assessment ability. The purpose of this study is to conduct a review of the published literature regarding the validity of the 8th AJCC TNM staging system, proposed modifications, and nomograms.

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The 8th AJCC is valid in prognostic stratification of gastric cancer, however, revisions are still required.

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The yPT staging requires some modifications and inclusion of stages that currently don't exist in the 8th AJCC.

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High lymph nodes count and anatomical localization improve the prediction ability of the current AJCC.

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Nomograms comprising of individual prognostic factors are crucial to the current AJCC.

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Molecular markers positively influence survival prediction of gastric cancer.

PD-1 Blockade Elicits Ongoing Remission in Two Cases of Refractory Epstein-Barr Virus Associated Metastatic Gastric Carcinoma

Introduction: Over the last decade immunotherapy has revolutionized oncological treatment of malignancies across all entities including gastric cancer. The programmed cell death protein 1 (PD-1) inhibitor pembrolizumab has demonstrated durable responses and survival benefit in distinct patient subgroups with advanced gastric cancer. In 2017, pembrolizumab monotherapy was approved by the U.S. Food and Drug Administration (FDA) for the treatment of refractory metastatic gastric cancer overexpressing PD-L1, as well as for refractory advanced tumors with deficient DNA mismatch repair/microsatellite instability (dMMR/MSI) or high tumor mutational burden (TMB-H). However, several biomarker unselected studies have reported only limited single-agent immunotherapeutic efficacy. Thus, the identification of predictive biomarkers to select patient subgroups who are most eligible for immunotherapy is of particular importance. A growing number of studies consider Epstein–Barr virus associated gastric cancer (EBVaGC) as a molecularly distinct and immunogenic subtype which might be particularly sensitive to immune checkpoint inhibition. Case report: Here we present two cases of heavily pretreated patients with refractory, metastatic EBVaGC, who experienced a significant and sustained response to monotherapy with the PD-1 checkpoint inhibitor pembrolizumab. Conclusion: Comprehensive genetic testing for predictive biomarkers (e.g. PD-L1, MSI/dMMR, tTMB, EBV) to identify patient subgroups most eligible for immunotherapy is of particular importance in advanced gastric cancer, especially in patients that are refractory to conventional chemotherapy.

The New Era of Immunotherapy in Gastric Cancer

Simple Summary

Advanced gastric cancer remains a malignancy with a poor prognosis, with a median survival of about 12–15 months. In recent years, immune checkpoint inhibitors have emerged as a new standard of care for several malignancies, including advanced gastric cancer, and have demonstrated good clinical benefit in some populations. In this review paper, we describe the current status of immunotherapy in gastric cancer, with a focus on molecular and immunological profiles, biomarkers, major clinical trials, and novel immunotherapies.

Abstract

Immune checkpoint inhibitors (ICIs) such as anti-programmed cell death-1 (PD-1) or programmed cell death ligand-1 (PD-L1) monoclonal antibodies have prolonged survival in various types of malignancies, including advanced gastric cancer (AGC). Nivolumab, a monoclonal anti-PD-1 antibody, showed an improvement in overall survival at a later-line therapy in unselected AGC patients in the ATTRACTION-2 study or in combination with chemotherapy as first-line therapy in the global CheckMate-649 study. Another monoclonal anti-PD-1 antibody, pembrolizumab, showed single agent activity in tumors with high microsatellite instability or high tumor mutational burden. Furthermore, a recent KEYNOTE-811 study demonstrated significant improvement in response rate with pembrolizumab combined with trastuzumab and chemotherapy for HER2-positive AGC. Based on these results, ICIs are now incorporated into standard treatment for AGC patients. As a result of pivotal clinical trials, three anti-PD-1 antibodies were approved for AGC: nivolumab combined with chemotherapy as first-line treatment or nivolumab monotherapy as third- or later-line treatment in Asian countries; pembrolizumab for previously treated microsatellite instability-high (MSI-H) or tumor mutational burden-high AGC, or pembrolizumab combined with trastuzumab and chemotherapy for HER2-positive AGC in the United States; and dostarlimab for previously treated MSI-H AGC in the United States. However, a substantial number of patients have showed resistance to ICIs, highlighting the importance of the better selection of patients or further combined immunotherapy. This review focused on molecular and immunological profiles, pivotal clinical trials of ICIs with related biomarkers, and investigational immunotherapy for AGC.

Deep Learning based on hematoxylin-eosin staining outperforms immunohistochemistry in predicting molecular subtypes of gastric adenocarcinoma

In gastric cancer (GC), there are four molecular subclasses that indicate whether patients respond to chemotherapy or immunotherapy, according to the TCGA. In clinical practice, however, not every patient undergoes molecular testing. Many laboratories have used well-implemented in situ techniques (IHC and EBER-ISH) to determine the subclasses in their cohorts. Although multiple stains are used, we show that a staining approach is unable to correctly discriminate all subclasses. As an alternative, we trained an ensemble convolutional neuronal network using bagging that can predict the molecular subclass directly from hematoxylin-eosin histology. We also identified patients with predicted intra-tumoral heterogeneity or with features from multiple subclasses, which challenges the postulated TCGA-based decision tree for GC subtyping. In the future, Deep Learning may enable targeted testing for molecular subtypes and targeted therapy for a broader group of GC patients. This article is protected by copyright. All rights reserved.

Prognostic Value of Programmed Death Ligand-1 Expression in Solid Tumors Irrespective of Immunotherapy Exposure: A Systematic Review and Meta-Analysis

BACKGROUND

The programmed cell death-1/programmed cell death ligand-1 (PD-L1) pathway, which plays a crucial role in cancer immune surveillance, is the target of several approved immunotherapeutic agents and is used as a predictive biomarker in some solid tumors. However, its use as a prognostic marker (i.e., regardless of therapy used) is not established clearly with available data demonstrating inconsistent prognostic impact of PD-L1 expression in solid tumors.

METHODS

We conducted a systematic literature search of electronic databases and identified publications exploring the effect of PD-L1 expression on overall survival and/or disease-free survival. Hazard ratios were pooled in a meta-analysis using generic inverse-variance and random-effects modeling. We used the Deeks method to explore subgroup differences based on disease site, stage of disease, and method of PD-L1 quantification.

RESULTS

One hundred and eighty-six studies met the inclusion criteria. Programmed cell death ligand-1 expression was associated with worse overall survival (hazard ratio 1.33, 95% confidence interval 1.26-1.39; p < 0.001). There was significant heterogeneity between disease sites (subgroup p = 0.002) with pancreatic, hepatocellular, and genitourinary cancers associated with the highest magnitude of adverse outcomes. Programmed cell death ligand-1 was also associated with worse overall disease-free survival (hazard ratio 1.19, 95% confidence interval 1.09-1.30; p < 0.001). Stage of disease did not significantly affect the results (subgroup p = 0.52), nor did the method of quantification via immunohistochemistry or messenger RNA (subgroup p = 0.70).

CONCLUSIONS

High expression of PD-L1 is associated with worse survival in solid tumors albeit with significant heterogeneity among tumor types. The effect is consistent in early-stage and metastatic disease and is not sensitive to method of PD-L1 quantification. These data can provide additional information for the counseling of patients with cancer about prognosis.

Differential Expression of Genes Involved in Metabolism and Immune Response in Diffuse and Intestinal Gastric Cancers, a Pilot Ptudy

Gastric cancer (GC) is one of the major causes of cancer-related mortality worldwide. The vast majority of GC cases are adenocarcinomas including intestinal and diffuse GC. The incidence of diffuse GCs, often associated with poor overall survival, has constantly increased in USA and Europe The molecular basis of diffuse GC aggressivity remains unclear. Using mRNA from diffuse and intestinal GC tumor samples of a Western cohort, this study reports the expression level of the immunomodulatory aryl-hydrocarbon receptor (AhR), and genes involved in immune suppression (PD1, PD-L1, PD-L2) and the early steps of tryptophan metabolism (IDO1, IDO2, TDO2). Strongly increased expression of IDO1 (p < 0.001) and PD1 (p < 0.003) was observed in the intestinal sub-type. The highest expression of IDO1 and PDL1 correlated with early clinical stage and absence of lymphatic invasion (×25 p = 0.004, ×3 p = 0.04, respectively). Our results suggest that kynurenine, produced by tryptophan catabolism, and AhR activation play a central role in creating an immunosuppressive environment. Correspondingly, as compared to intestinal GCs, expression levels of IDO1-TDO2 and PD-L1 were less prominent in diffuse GCs which also had less infiltration of immune cells, suggesting an inactive immune response in the advanced diffuse GC. Confirmation of these patterns of gene expression will require a larger cohort of early and advanced stages of diffuse GC samples.

Immune Score Predicts Outcomes of Gastric Cancer Patients Treated with Adjuvant Chemoradiotherapy

Background

Substantial evidence has demonstrated that tumor-infiltrating lymphocytes (TILs) are correlated with patient prognosis. The TIL-based immune score (IS) affects prognosis in various cancers, but its prognostic impact in gastric cancer (GC) patients treated with adjuvant chemoradiotherapy remains unclear.

Methods

A total of 101 GC patients who received chemoradiotherapy after gastrectomy were retrospectively analyzed in this study. Immunohistochemistry staining for CD3+ and CD8+ T-cell counts in both tumor center (CT) and invasive margin (IM) regions was built into the IS. Patients were then divided into three groups based on their differential IS levels. The correlation between IS and clinical parameters was analyzed. The prognostic impact of IS and clinical parameters was evaluated using Kaplan-Meier analysis and Cox proportional hazard regression analysis. Receiver operating characteristic (ROC) curves were plotted to compare the area under the curve (AUC) of IS with other clinical parameters. Nomograms for disease-free survival (DFS) and overall survival (OS) prediction were constructed based on the identified parameters.

Results

Finally, 20 (19.8%), 57 (56.4%), and 24 (23.8%) GC patients were identified with low, intermediate, and high IS levels, respectively. GC patients with higher IS levels exhibited better DFS (p < 0.001) and OS (p < 0.001). IS was an independent prognostic factor for both DFS (p < 0.001) and OS (p < 0.001) in multivariate analysis. IS presented a better predictive ability than the traditional pathological tumor-node-metastasis (pTNM) staging system (AUC: 0.801 vs. 0.677 and 0.800 vs. 0.660, respectively) with respect to both DFS and OS. The C-index of the nomograms for DFS and OS prediction was 0.737 and 0.774, respectively.

Conclusions

IS is a strong predictive factor for both DFS and OS in GC patients treated with adjuvant chemoradiotherapy, which may complement the traditional pTNM staging system.

Prognostic significance of natural killer cell-associated markers in gastric cancer: quantitative analysis using multiplex immunohistochemistry

BACKGROUND

Natural killer (NK) cells mediate the anti-tumoral immune response as an important component of innate immunity. The aim of this study was to investigate the prognostic significance and functional implication of NK cell-associated surface receptors in gastric cancer (GC) by using multiplex immunohistochemistry (mIHC).

METHODS

We performed an mIHC on tissue microarray slides, including 55 GC tissue samples. A total of 11 antibodies including CD57, NKG2A, CD16, HLA-E, CD3, CD20, CD45, CD68, CK, SMA, and ki-67 were used. CD45 + CD3-CD57 + cells were considered as CD57 + NK cells.

RESULTS

Among CD45 + immune cells, the proportion of CD57 + NK cell was the lowest (3.8%), whereas that of CD57 + and CD57- T cells (65.5%) was the highest, followed by macrophages (25.4%), and B cells (5.3%). CD57 + NK cells constituted 20% of CD45 + CD57 + immune cells while the remaining 80% were CD57 + T cells. The expression of HLA-E in tumor cells correlated with that in tumoral T cells, B cells, and macrophages, but not CD57 + NK cells. The higher density of tumoral CD57 + NK cells and tumoral CD57 + NKG2A + NK cells was associated with inferior survival.

CONCLUSIONS

Although the number of CD57 + NK cells was lower than that of other immune cells, CD57 + NK cells and CD57 + NKG2A + NK cells were significantly associated with poor outcomes, suggesting that NK cell subsets play a critical role in GC progression. NK cells and their inhibitory receptor, NKG2A, may be potential targets in GC.

Epstein-Barr Virus-Associated Gastric Cancer: Old Entity with New Relevance

Gastric cancer (GC) represents a major public health issue worldwide, being the fifth most common cancer and one of the leading causes of death by cancer. In 2014, The Cancer Genome Atlas (TCGA) established that tumors positive for Epstein-Barr virus (EBV) are considered a specific subtype of GC (EBVaGC). Several meta-analyses have shown that EBVaGC represents almost 10% of all gastric cancer worldwide, with small differences in the geographic distribution. This tumor subtype has a high potential of being clinically relevant and studies have shown that it has specific features, a better prognosis, and increased overall survival. In this review, we summarize some of the most frequent aspects of EBVaGC, including the specific features of this GC subtype, data regarding the potential steps of EBVaGC carcinogenesis, and perspectives on treatment opportunities.

Randomized, open-label, phase 2 study of andecaliximab plus nivolumab versus nivolumab alone in advanced gastric cancer identifies biomarkers associated with survival

Background

Matrix metalloproteinase-9 (MMP9) selectively cleaves extracellular matrix proteins contributing to tumor growth and an immunosuppressive microenvironment. This study evaluated andecaliximab (ADX), an inhibitor of MMP9, in combination with nivolumab (NIVO), for the treatment of advanced gastric cancer.

Methods

Phase 2, open-label, randomized multicenter study evaluating the efficacy, safety, and pharmacodynamics of ADX+NIVO versus NIVO in patients with pretreated metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and adverse events (AEs). We explored the correlation of efficacy outcomes with biomarkers.

Results

144 patients were randomized; 141 were treated: 81% white, 69% male, median age was 61 years in the ADX+NIVO group and 62 years in the NIVO-alone group. The ORR was 10% (95% CI 4 to 19) in the ADX+NIVO group and 7% (95% CI 2 to 16) in the NIVO-alone group (OR: 1.5 (95% CI 0.4 to 6.1; p=0.8)). There was no response or survival benefit associated with adding ADX. AE rates were comparable in both treatment groups; the most common AEs were fatigue, decreased appetite, nausea, and vomiting. Programmed cell death ligand 1, interferon-γ (IFN), and intratumoral CD8+ cell density were not associated with treatment response or survival. The gene signature most correlated with shorter survival was the epithelial-to-mesenchymal gene signature; high transforming growth factor (TGF)-β fibrosis score was negatively associated with OS (p=0.036). Gene expression analysis of baseline tumors comparing long-(1+ years) and short-term (<1 year) survivors showed that GRB7 was associated with survival beyond 1 year. Human epidermal growth factor receptor 2 (HER2)-positive disease was associated with significantly longer survival (p=0.0077). Median tumor mutation burden (TMB) was 2.01; patients with TMB ≥median had longer survival (p=0.0025) and improved PFS (p=0.016). Based on a model accounting for TMB, TGF-β fibrosis, and HER2, TMB was the main driver of survival in this patient population.

Conclusion

Combination of ADX+NIVO had a favorable safety profile but did not improve efficacy compared with NIVO alone in patients with pretreated metastatic gastric or GEJ adenocarcinoma. HER2 positivity, higher TMB or GRB7, and lower TGF-β were associated with improved outcomes.

Trial registration number

NCT02864381 or GS-US-296–-2013.

Biomarker-targeted therapies for advanced-stage gastric and gastro-oesophageal junction cancers: an emerging paradigm

Advances in cancer biology and sequencing technology have enabled the selection of targeted and more effective treatments for individual patients with various types of solid tumour. However, only three molecular biomarkers have thus far been demonstrated to predict a response to targeted therapies in patients with gastric and/or gastro-oesophageal junction (G/GEJ) cancers: HER2 positivity for trastuzumab and trastuzumab deruxtecan, and microsatellite instability (MSI) status and PD-L1 expression for pembrolizumab. Despite this lack of clinically relevant biomarkers, distinct molecular subtypes of G/GEJ cancers have been identified and have informed the development of novel agents, including receptor tyrosine kinase inhibitors and monoclonal antibodies, several of which are currently being tested in ongoing trials. Many of these trials include biomarker stratification, and some include analysis of circulating tumour DNA (ctDNA), which both enables the noninvasive assessment of biomarker expression and provides an indication of the contributions of intratumoural heterogeneity to response and resistance. The results of these studies might help to optimize the selection of patients to receive targeted therapies, thus facilitating precision medicine approaches for patients with G/GEJ cancers. In this Review, we describe the current evidence supporting the use of targeted therapies in patients with G/GEJ cancers and provide guidance on future research directions.

Expression of the immune checkpoint receptors PD-1, LAG3, and TIM3 in the immune context of stage II and III gastric cancer by using single and chromogenic multiplex immunohistochemistry

We sought to determine the clinicopathological significance of PD-1, LAG3, and TIM3 in gastric cancer (GC) by examining their expression and immune context. Immunohistochemistry (IHC) for PD-1, TIM3, LAG3, and tumor-infiltrating immune cell (TIIC) markers was performed in 385 stage II/III GCs. Epstein-Barr virus (EBV) and microsatellite stability (MSI) testing were performed for molecular classification. Chromogenic multiplex IHC (mIHC) for PD1, TIM3, LAG3, CD3, CD8, FOXP3, CD68, and cytokeratin was performed in 58 of the total samples. PD-1, LAG3, and TIM3 expression in TIICs was observed in 91 (23.6%), 193 (50.1%), and 257 (66.8%) GCs by single IHC, respectively. The expression was associated with EBV⁺ and MSI-H molecular subtypes (p ≤ 0.001). A positive expression of LAG3 in the invasive margin of the tumor was associated with better prognosis in univariate (p = .020) and multivariate (p = .026) survival analyses. The expression of different immune checkpoint receptors (ICRs) was significantly positively correlated. Dual or triple ICR expression was more frequent in high PD-1 and TIM3 density groups than in low-density groups by mIHC (all p ≤ 0.05). ICRs were mainly expressed in CD3⁺CD8⁺ and CD3⁺CD8⁻ T cells. Fifty-eight GCs were classified into three groups by clustering analysis based on mIHC, and the group with the highest ICR expression in TIICs showed significantly better outcomes in progression-free survival (p = .020). In GC, PD-1, LAG3, and TIM3 expression is positively correlated and associated with better prognosis. Our study provides information for the application of effective immune checkpoint inhibitors against GC.

Correlation between tumor infiltrating immune cells and peripheral regulatory T cell determined using methylation analyses and its prognostic significance in resected gastric cancer

Peripheral regulatory T cells (pTregs) are a highly immunosuppressive fraction of CD4+ T cells. We aimed to evaluate the clinical significance of pTregs in patients with gastric cancer and to determine the correlation between pTregs and immune cell infiltration in tumor microenvironment. pTregs status was determined by assessing the pTreg/total T-cell ratio (ratio of Foxp3 Treg-specific demethylated region (TSDR) to CD3G/CD3D demethylation, so-called Cellular Ratio of Immune Tolerance “ImmunoCRIT”) using methylation analyses in 433 patients with gastric cancer who received curative surgery. Among 422 evaluable patients, 230 (54.5%) had high ImmunoCRIT (> 21.0). Patients with high ImmunoCRIT had significantly shorter disease-free survival (DFS) and overall survival (OS) than those with high ImmunoCRIT (p = 0.030, p = 0.008, respectively). In multivariate analysis, high ImmunoCRIT kept a prognostic role for shorter OS (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.4–2.9; p = 0.005). CD3+ cell density and CD4+ cell density was significantly higher within the tumor in high ImmunoCRIT group than those in low ImmunoCRIT group (CD3+ cell, 202.12/mm²vs. 172.2/mm², p = 0.029; CD4+ cell, 56.5/mm²vs. 43.5/mm², p = 0.007). In conclusion, the peripheral ImmunoCRIT determined by epigenetic methylation analysis provides prognostic information in resected gastric tumors.

Next-Generation Digital Histopathology of the Tumor Microenvironment

Progress in cancer research is substantially dependent on innovative technologies that permit a concerted analysis of the tumor microenvironment and the cellular phenotypes resulting from somatic mutations and post-translational modifications. In view of a large number of genes, multiplied by differential splicing as well as post-translational protein modifications, the ability to identify and quantify the actual phenotypes of individual cell populations in situ, i.e., in their tissue environment, has become a prerequisite for understanding tumorigenesis and cancer progression. The need for quantitative analyses has led to a renaissance of optical instruments and imaging techniques. With the emergence of precision medicine, automated analysis of a constantly increasing number of cellular markers and their measurement in spatial context have become increasingly necessary to understand the molecular mechanisms that lead to different pathways of disease progression in individual patients. In this review, we summarize the joint effort that academia and industry have undertaken to establish methods and protocols for molecular profiling and immunophenotyping of cancer tissues for next-generation digital histopathology-which is characterized by the use of whole-slide imaging (brightfield, widefield fluorescence, confocal, multispectral, and/or multiplexing technologies) combined with state-of-the-art image cytometry and advanced methods for machine and deep learning.

Immunoscore is a strong predictor of survival in the prognosis of stage II/III gastric cancer patients following 5-FU-based adjuvant chemotherapy

The prognostic impact of Immunoscore (IS) in gastric cancer (GC) patients treated with adjuvant chemotherapy remains unelucidated. We evaluated the CD3 + , CD8 + , and Foxp3 + T-lymphocyte densities in tumor centers and invasive margin regions of 389 patients with surgically resected stage II/III GC who received 5-FU-based adjuvant chemotherapy and investigated the impact of IS on survival. In univariate analysis, high CD3 + , CD8 + , and Foxp3 + T-lymphocyte densities in the invasive margin were correlated with better prognosis (all P < 0.05). Patients with high IS had significantly longer disease-free survival (DFS; P < 0.001) and overall survival (OS; P < 0.001). In multivariate analysis, IS demonstrated a powerful prognostic impact on patient outcome [DFS, hazard ratio (HR) = 0.465; 95% confidence interval (CI), 0.306-0.707, P < 0.001; OS, HR = 0.478; 95% CI, 0.308-0.743, P = 0.001]. Additionally, although all EBV-positive cases had high IS, IS was similar in both microsatellite instability (MSI)-high and microsatellite stable (MSS)/MSI-low groups (83.3% and 80.5%, respectively). Subgroup analysis according to MSI status revealed that high IS patients had significant DFS and OS benefits in both MSS/MSI-low (DFS, HR = 0.527, 95% CI, 0.341-0.816, P = 0.004; OS, HR = 0.528, 95% CI, 0.334-0.837, P = 0.007) and MSI-high (DFS, HR = 0.166, 95% CI, 0.033-0.826, P = 0.028; OS, HR = 0.177, 95% CI, 0.036-0.883, P = 0.035) groups. Thus, the assessment of immune cell infiltration based on IS may provide a strong indicator of survival in stage II/III GC patients with curative resection following 5-FU-based adjuvant chemotherapy.

Effect of Prognostic Nutrition Index in Gastric or Gastro-oesophageal Junction Cancer Patients Undergoing Nivolumab Monotherapy

BACKGROUND/AIM

We hypothesised that the prognostic nutrition index (PNI) is useful for evaluating host immunity and response to immune checkpoint inhibitors. We investigated the effect of PNI on nivolumab monotherapy efficacy in advanced or recurrent gastric cancer (GC) or gastro-oesophageal junction cancer (GOC) patients.

PATIENTS AND METHODS

We retrospectively examined 110 patients, divided them into a high-PNI group and a low-PNI group, and compared treatment efficacy, adverse events (AEs), and survival between the groups.

RESULTS

Median overall survival (OS) was significantly longer in the high-PNI group than in the low-PNI group (205 vs. 109 days; p<0.001). Multivariate analysis revealed that low PNI was an independent risk factor for OS (hazard ratio=2.398; 95% confidence interval=1.384-4.154; p=0.002). The overall response rate and frequency of AEs were not significantly different between the groups.

CONCLUSION

PNI could be a useful prognostic factor in GC or GOC patients undergoing nivolumab monotherapy.

Epstein-Barr virus-associated gastric cancer: disease that requires special approach

Epstein-Barr virus-associated gastric cancer [EBV-associated GC, EBV( +) GC] is a distinct molecular subtype of gastrointestinal (GI) cancers. It accounts for up to 10% of all molecular subtypes of gastric cancer (GC). It has unique genetic and epigenetic features, which determine its definitive phenotype with male and younger age predominance, proximal stomach localization, and diffuse adenocarcinoma histology. EBV( +) GC also has a unique epigenetic profile and mutational status with frequent mutations of PIK3CA, ARID1A and BCOR, and PD-L1 and PD-L2 amplifications, as well. The aim of this review is to highlight clinical significance of EBV( +) GC and prognostic role of EBV infection, and to determine potentially appropriate drug therapy for this disease.

CD8+ Tumour-Infiltrating Lymphocytes and Tumour Microenvironment Immune Types as Biomarkers for Immunotherapy in Sinonasal Intestinal-Type Adenocarcinoma

BACKGROUND

Intestinal-type adenocarcinoma (ITAC) is a rare tumour occurring in the ethmoid sinus. Recent years have brought advances in endoscopic surgery and precision radiotherapy; however, five-year overall survival has not improved and remains at 35-80%, depending on tumour stage and histology. Therefore, there is a need for new therapeutic options.

METHODS

We evaluated CD8⁺ tumour-infiltrating lymphocytes (TILs) and tumour microenvironment immune type (TMIT, combining CD8⁺ TILs and PD-L1) as predictive biomarkers for immunotherapy in a series of 133 ITAC. All results were correlated to clinical and follow-up data.

RESULTS

The presence of intratumoural CD8⁺ TILs was low in 57% of cases and high in 8% of cases. Tumoural PD-L1 positivity was observed in 26% of cases. CD8⁺ TILs and TMIT correlated with the histological subtype of ITAC and with better overall survival. The presence of stromal PD-L1-positive macrophages was related to intratumoural CD8⁺ TILs. PD-L1 expression on tumour cells or macrophages did not show prognostic value.

CONCLUSIONS

TMIT classification did not have additional prognostic value over CD8⁺ TILs alone. The modest percentage of CD8^high/PD-L1^pos cases indicates that ITAC is a lowly immunogenic tumour type. Nevertheless, a proportion of ITAC, especially the papillary and colonic subtypes, could benefit from therapy with immune checkpoint inhibitors.

Differential prognostic impact of CD8+ T cells based on human leucocyte antigen I and PD-L1 expression in microsatellite-unstable gastric cancer

BACKGROUND

The aim of the study was to determine the human leucocyte antigen class-I (HLA-I), programmed death-ligand 1 (PD-L1) expression and tumour-infiltrating lymphocytes (TILs) of microsatellite instability-high gastric cancer.

METHODS

The HLA-I expression type was determined by immunohistochemistry of HLA-A, HLA-B, HLA-C and β2-microglobulin in the centre of the tumour (CT) and in the invasive margin (IM) of samples from 293 patients (total loss vs. preserved type). PD-L1 expression and TIL density was examined immunohistochemically. HLA-I genotyping was also performed.

RESULTS

The expression loss of the HLA-I molecules was significantly associated with low TIL density. According to survival analyses, the HLA-I expression type and PD-L1 positivity were not independent prognostic factors. The TIL density had no prognostic implication when survival analysis was performed for the whole patient group; however, high CD8⁺ TIL infiltration was significantly associated with good prognosis in only HLA-I-preserved-type/PD-L1-positive group (p = 0.034). The homozygosity of the HLA-I allele was more frequently observed in the total loss type group.

CONCLUSIONS

We confirmed differential prognostic implication of CD8⁺ TILs according to the HLA-I and PD-L1 expression. Determination of the HLA-I expression could be helpful to select patients who would benefit from anti-PD-1/PD-L1 therapy.

Thirty years of Epstein-Barr virus-associated gastric carcinoma

Thirty years have passed since a possible association of Epstein-Barr virus (EBV) with gastric carcinoma was reported. We now know EBV-associated gastric carcinoma to be a specific subtype of gastric carcinoma. Global epigenetic methylation and counteraction of the antitumour microenvironment are two major characteristics of this subtype of gastric carcinoma. Recent development of therapeutic modalities for gastric carcinoma, such as endoscopic mucosal dissection and immune checkpoint inhibitor therapy, has made the presence of EBV infection a biomarker for the treatment of gastric carcinoma. This review presents a portrait of EBV-associated gastric carcinoma from initiation to maturity that we define as the 'gastritis-infection-cancer sequence', followed by its molecular abnormalities and interactions with immune checkpoint molecules and the microenvironment. EBV non-coding RNAs (microRNA and circular RNA) and exosomes derived from EBV-infected cells that were previously behind the scenes are now recognized for their roles in EBV-associated gastric carcinoma. The virus utilizes cellular machinery skilfully to control infected cells and their microenvironment. We should thus strive to understand virus-host interactions more fully in the following years to overcome this virus-driven subtype of gastric carcinoma.

The landscape and prognostic value of tumor-infiltrating immune cells in gastric cancer

Background

Gastric cancer (GC) is the fourth most frequently diagnosed malignancy and the second leading cause of cancer-associated mortality worldwide. The tumor microenvironment, especially tumor-infiltrating immune cells (TIICs), exhibits crucial roles both in promoting and inhibiting cancer growth. The aim of the present study was to evaluate the landscape of TIICs and develop a prognostic nomogram in GC.

Materials and Methods

A gene expression profile obtained from a dataset from The Cancer Genome Atlas (TCGA) was used to quantify the proportion of 22 TIICs in GC by the CIBERSORT algorithm. LASSO regression analysis and multivariate Cox regression were applied to select the best survival-related TIICs and develop an immunoscore formula. Based on the immunoscore and clinical information, a prognostic nomogram was built, and the predictive accuracy of it was evaluated by the area under the curve (AUC) of the receiver operating characteristic curve (ROC) and the calibration plot. Furthermore, the nomogram was validated by data from the International Cancer Genome Consortium (ICGC) dataset.

Results

In the GC samples, macrophages (25.3%), resting memory CD4 T cells (16.2%) and CD8 T cells (9.7%) were the most abundant among 22 TIICs. Seven TIICs were filtered out and used to develop an immunoscore formula. The AUC of the prognostic nomogram in the TCGA set was 0.772, similar to that in the ICGC set (0.730) and whole set (0.748), and significantly superior to that of TNM staging alone (0.591). The calibration plot demonstrated an outstanding consistency between the prediction and actual observation. Survival analysis revealed that patients with GC in the high-immunoscore group exhibited a poor clinical outcome. The result of multivariate analysis revealed that the immunoscore was an independent prognostic factor.

Discussion

The immunoscore could be used to reinforce the clinical outcome prediction ability of the TNM staging system and provide a convenient tool for risk assessment and treatment selection for patients with GC.

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.

Clinicopathologic significance of human leukocyte antigen class I expression in patients with stage II and III gastric cancer

Human leukocyte antigen class I (HLA I) molecules composed of alpha (heavy) chain, including HLA-A, -B, or -C encoded by HLA genes, and beta-2-microglobulin (β2M) are membrane proteins on all nucleated cells that display peptide antigens for recognition by CD8-positive cytotoxic T cells. Here, we examined the clinicopathologic signification of HLA I expression in patients with gastric cancer (GC). Immunohistochemistry was performed to detect HLA A/B/C, β2M, CD8, p53, and programmed death-ligand 1 (PD-L1) in the center and invasive margin of the tumor in 395 stage II and III GCs using tissue array method. Additionally, Epstein-Barr virus (EBV) infection and microsatellite instability (MSI) status were investigated. Negative expression of HLA A/B/C and β2M was observed in 258 (65.3%) and 235 (59.5%) of 395 stage II and III GCs, respectively. Negative HLA I expression was significantly associated with aggressive clinicopathologic features. Furthermore, negative expression of HLA A/B/C and β2M was inversely correlated with CD8-positive cytotoxic T cell infiltration, EBV-positivity, and PD-L1 expression (all p < 0.001). Patients with HLA A/B/C-negative GC had worse overall survival (OS) (p = 0.019) and combined analysis with both HLA A/B/C and β2M expression status significantly predicted OS in univariate (p = 0.004) and multivariate survival analysis (p = 0.016). Negative expression of HLA A/B/C and β2M was frequently observed in stage II and III GCs, particularly with the aggressive clinicopathologic features, and correlated with an unfavorable prognosis and host immune response status. These findings contribute to further development of immunotherapy.

Clinical and molecular prognostic markers of survival after surgery for gastric cancer: tumor-node-metastasis staging system and beyond

For accurately predicting prognosis and for effectively describing cancer states at a certain point during treatment to other care providers and patients, various staging systems have been utilized in gastric cancer. Among these, the UICC/AJCC tumor-node-metastasis (TNM) staging system is most widely used. However, even within the same substage, gastric cancers can vary substantially in regards to prognosis after treatment. For more accurate and individualized prognostication, staging systems have been found to benefit from including molecular markers and genomic subtypes, in addition to clinicopathological parameters, such as age, sex, tumor size, tumor location, Lauren classification, number of lymph nodes resected, extent of surgical resection, lymphovascular invasion, and adjuvant chemotherapy. In this review article, we review and summarize relevant biomarkers for gastric cancer that can be incorporated into the current anatomy-based TNM staging system, as well as results from validation studies thereof.

Development and Validation of an Easy-to-Implement, Practical Algorithm for the Identification of Molecular Subtypes of Gastric Cancer: Prognostic and Therapeutic Implications

BACKGROUND

Gastric cancer (GC) is a heterogeneous disease, and substantial efforts have been made to develop a molecular biology-based classification system for GC. Analysis of the genomic signature is not always feasible, and thus, we aimed to (i) develop and validate a practical immunohistochemistry (IHC)- and polymerase chain reaction (PCR)-based molecular classification of GC and (ii) to assess HER2 status according to this classification.

MATERIALS AND METHODS

A total of 894 consecutive patients with GC from two individual cohorts (training, n = 507; validation, n = 387) were classified using Epstein-Barr virus (EBV) in situ hybridization, microsatellite instability (MSI) testing, and IHC for E-cadherin and p53.

RESULTS

We were able to classify patients into five groups in the training cohort: group 1 (MSI⁺), group 2 (EBV^-, MSI^-, non-epithelial-mesenchymal transition [non-EMT]-like, p53^-), group 3 (EBV⁺), group 4 (EBV^-, MSI^-, non-EMT-like, p53⁺), and group 5 (EBV^-, MSI^-, EMT-like). In the training cohort, each group showed different overall survival (OS) after gastrectomy (p < .001); group 1 had the best prognosis, and group 5 showed the worst survival outcome. The significant impact of the classification system on OS was also verified in the validation cohort (p = .004). HER2 positivity was observed in 6.5% of total population, and most of HER2-positive cases (93.1%) were included in groups 2 and 4.

CONCLUSION

We developed and validated a modified IHC- and PCR-based molecular classification system in GC, which showed significant impact on survival, irrespective of stage or other clinical variables. We also found close association between HER2 status and non-EMT phenotype in our classification system.

IMPLICATIONS FOR PRACTICE

Molecular classification of gastric cancer suggested by previous studies mostly relies on extensive genomic data analysis, which is not always available in daily practice. The authors developed a simplified immunohistochemistry- and polymerase chain reaction-based molecular classification of gastric cancer and proved the prognostic significance of this classification, as well as the close association between HER2 status and certain groups of the classification, in the largest consecutive cohort of gastric cancer. Results of this study suggest that this scheme is a cost-effective, easy-to-implement, and feasible way of classifying gastric cancer in daily clinical practice, also serving as a practical tool for aiding therapeutic decisions and predicting prognosis.

Tumor microenvironment immune types in gastric cancer are associated with mismatch repair however, not HER2 status

The treatment of patients with human epidermal growth factor receptor 2 (HER2)-negative gastric cancer is a major challenge. Immunotherapy using immune checkpoint inhibitors is a rapidly growing field. In a number of malignancy types it has been demonstrated that patients with mismatch repair deficiency efficiently respond to programmed death-ligand 1 (PD-L1) blockade therapy. Recent studies have evaluated tumor microenvironment immune types to predict which patients may clinically benefit from immunotherapy. The present study aimed to evaluate the immunohistochemical expression of PD-L1 in 70 gastric cancer tissue samples. Potential associations between PD-L1 expression and mismatch repair deficiency, HER2 and Epstein Barr virus (EBV) status were then investigated in the context of the tumor microenvironment. A positive association was identified for PD-L1 expression with mismatch repair deficiency and EBV status; however, no association was revealed with HER2 status. Immunohistochemistry was then used to classify the microenvironment immune types. This demonstrated that the majority of the gastric cancer samples (73%) belonged to the tumor microenvironment immune type II [PD-L1-/cluster of differentiation 8 (CD8)+ low], which involves an immune ignorant state and has a low sensitivity to immunotherapy. However, 7% of the gastric cancer cases were identified to belong to the tumor microenvironment immune type I (PD-L1+/CD8+ high), which exhibits adaptive immune escape responses and a high chance of reversion with immune checkpoint blockade therapy. In conclusion, the present study emphasized the importance of evaluating tumor microenvironment immune types, mismatch repair deficiency status and EBV status, rather than PD-L1 expression alone, when evaluating the eligibility of a patient for immunotherapy with anti-programmed cell death protein-1/PD-L1 antibodies.

Prognostic Significance of Programmed Death Ligand 1 Expression and Tumor-Infiltrating Lymphocytes in Axial Osteosarcoma

OBJECTIVE

To characterize the intratumoral immune microenvironment and evaluate its clinical implications in patients with primary axial osteosarcoma.

METHODS

Immunohistochemistry was used to interpret tumor programmed death ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes (TILs) profile of cluster of differentiation 8 (CD8), PD-L1, and programmed death 1 (PD-1) within 69 tumor specimens.

RESULTS

Overall, all tumor specimens presented lymphocytic infiltrates, with PD-L1+ TILs being the most common subset (mean, 215.1 per slide mm²). Positive tumor PD-L1 expression was presented in 43.5% of tumors. Moderate to strong relationships were detected among TILs subsets and tumor PD-L1 expression. In addition, the density of PD-L1+ TILs was significantly correlated with favorable clinicopathologic features, including earlier Enneking stage. The positivity of tumor PD-L1 expression was associated with the tumor site and pathologic grade (P = 0.021 and 0.037, respectively). In univariate survival analysis, the high density of PD-L1+ TILs or CD8+ TILs was significantly correlated with both prolonged event-free survival and overall survival (OS), whereas the high infiltration of PD-1+ TILs was significantly associated with reduced OS, as was the positive tumor PD-L1 expression. Furthermore, multivariate analysis showed that CD8+ TILs and PD-L1+ TILs remained their significance for both event-free survival (P = 0.012 and 0.004, respectively) and OS (P = 0.033 and 0.002, respectively). However, both PD-1+ TILs and tumor PD-L1 expression failed to reach significance for OS.

CONCLUSIONS

Our results suggested that the immune microenvironment is of clinically relevant significance in patients with axial osteosarcoma. Specifically, we identified both PD-L1+ TILs and CD8+ TILs as independent favorable prognostic markers.

Prognostic impact of p16 and PD-L1 expression in patients with oropharyngeal squamous cell carcinoma receiving a definitive treatment

Aims

Limited information is available regarding the precise differences in the tumour immune microenvironment (TIM) of patients with human papilloma virus (HPV)-associated and non-HPV-associated oropharyngeal squamous cell carcinoma (OPSCC). Here, we retrospectively reviewed 137 patients with OPSCC treated with a definitive treatment to identify molecular relationships in the TIM.

Materials and methods

We used immunohistochemical analysis to assess p16 status, programmed death ligand 1 (PD-L1) level, and/or CD8⁺ tumour-infiltrating lymphocyte (TIL) density, followed by prognostic evaluation of these immune-related parameters.

Results

Multivariate analyses demonstrated that PD-L1 level on immune cells but not on tumour cells or CD8⁺ TIL density was a significant predictive factor of disease-free survival (DFS) and overall survival (OS). Additionally, subgroup analyses demonstrated that patients positive for p16 and PD-L1 expression on immune cells had favourable DFS and OS, whereas patients negative for p16 and PD-L1 expression on immune cells showed worse DFS and OS.

Conclusions

We demonstrated that PD-L1 expression on immune cells but not tumour cells might represent a useful prognostic biomarker in patients with OPSCC receiving a definitive treatment. We propose that a co-assessment of p16 and PD-L1 expression on immune cells would have greater prognostic potential compared with evaluation of each factor alone in patients with OPSCC.

A subset of diffuse-type gastric cancer is susceptible to mTOR inhibitors and checkpoint inhibitors

Background

Mechanistic target of rapamycin (mTOR) pathway is essential for the growth of gastric cancer (GC), but mTOR inhibitor everolimus was not effective for the treatment of GCs. The Cancer Genome Atlas (TCGA) researchers reported that most diffuse-type GCs were genomically stable (GS). Pathological analysis suggested that some diffuse-type GCs developed from intestinal-type GCs.

Methods

We established patient-derived xenograft (PDX) lines from diffuse-type GCs, and searched for drugs that suppressed their growth. Diffuse-type GCs were classified into subtypes by their gene expression profiles.

Results

mTOR inhibitor temsirolimus strongly suppressed the growth of PDX-derived diffuse-type GC-initiating cells, which was regulated via Wnt-mTOR axis. These cells were microsatellite unstable (MSI) or chromosomally unstable (CIN), inconsistent with TCGA report. Diffuse-type GCs in TCGA cohort could be classified into two clusters, and GS subtype was major in cluster I while CIN and MSI subtypes were predominant in cluster II where PDX-derived diffuse-type GC cells were included. We estimated that about 9 and 55% of the diffuse-type GCs in cluster II were responders to mTOR inhibitors and checkpoint inhibitors, respectively, by identifying PIK3CA mutations and MSI condition in TCGA cohort. These ratios were far greater than those of diffuse-type GCs in cluster I or intestinal-type GCs. Further analysis suggested that diffuse-type GCs in cluster II developed from intestinal-type GCs while those in cluster I from normal gastric epithelial cells.

Conclusion

mTOR inhibitors and checkpoint inhibitors might be useful for the treatment of a subset of diffuse-type GCs which may develop from intestinal-type GCs.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1121-3) contains supplementary material, which is available to authorized users.

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.

Somatic mutational profiles of stage II and III gastric cancer according to tumor microenvironment immune type

We aimed to determine somatic mutational profiles of stage II/III gastric cancers (GCs) according to their tumor microenvironment immune types (TMITs), which classify cancer based on co-assessment of PD-L1 expression and CD8⁺ tumor infiltrating lymphocytes. Eighty patients with stage II/III GC were classified as follows: TMIT I (PD-L1⁺ /CD8^High ), TMIT II (PD-L1^- /CD8^Low ), TMIT III (PD-L1⁺ /CD8^Low ), and TMIT IV (PD-L1^- /CD8^High ). Deep targeted sequencing using a panel of 170 cancer-related genes was performed on an Illumina HiSeq-2500 system. Most frequently mutated genes included GNAQ (41.3%), TP53 (38.8%), CREBBP (35.0%), and MAP3K1 (35.0%). PIK3CA mutations were observed more frequently in TMIT I (45.8%) and III (66.7%), than in II (12.0%) and IV (8.0%). Other genes with enriched mutations within TMIT I included ATM (33.3%), BRCA2 (33.3%), MAP3K4 (29.2%), and FLT4 (25.0%). FGFR3, MAP3K1, and RUNX1 mutations were more frequently found in TMIT II. TMIT III had a unique somatic mutation profile harboring enriched mutations of histone modifiers including CREBBP and KMT2A, and we found FGFR2 amplification exclusively within TMIT IV. Fuzzy clustering analysis based on somatic mutation frequencies identified a hypermutated group (cluster 1) and a hypomutated group (cluster 2). Cluster 1 had significant associations with TMIT I, EBV⁺ GCs, and MSI-H GCs (P = .023, .014, and .004), and had better overall survival (P = .057) than Cluster 2. TMIT I, EBV⁺ , and MSI-H GCs were estimated to have greater tumor mutational burden (P = .023, .003, and .015). By analyzing somatic mutation profiles according to TMIT classification, we identified TMIT-specific genetic alterations that provide clues for biological linkage between GC genetics and microenvironment.

Computational measurement of tumor immune microenvironment in gastric adenocarcinomas

The use of four groups of tumor immune microenvironments (TME) based on PD-L1 and tumor-infiltrating T lymphocytes (TIL) is a reliable biomarker for anti-PD-1/PD-L1 inhibitor therapy. We classified the TME in 241 gastric cancers which were subdivided according to 40 EBV+, 76 microsatellite instability-high (MSI-H), and 125 EBV-/microsatellite-stable (MSS) subtypes by quantitative image analysis (QIA) and correlated the results with mRNA expression levels. The mean PD-L1 ratio and CD8 ratio in EBV+, MSI-H, and EBV−/MSS GCs were significantly different (P < 0.006). The PD-L1 ratio and CD8 ratio obtained by QIA correlated well with the RNA levels of PD-L1 (r = 0.63) and CD8 (r = 0.67), respectively. The TME were type I (PD-L1^H/CD8^H) in 45, type II (PD-L1^L/CD8^L) in 106, type III (PD-L1^H/CD8^L) in 8, and type IV (PD-L1^L/CD8^H) in 82 cases. The type I TME was significantly associated with high TIL (P = 3.0E-11) and EBV+ status (P = 8.55E-08). In conclusion, QIA results correlated well with the mRNA expression levels and classified TME of gastric cancers.

PD-L1 Expression On tumor Cells Was Associated With Unfavorable Prognosis In Esophageal Squamous Cell Carcinoma

Background: Evidence about the association between programmed cell death ligand 1 (PD-L1) expression and prognosis of esophageal squamous cell carcinoma (ESCC) were limited and controversial. Thus, the present study aims to investigate the prognostic value of tumor immune microenvironment (TIM) based on PD-L1 expression and CD8+ T cell infiltration in ESCC tissues.

Methods: From September 2008 to March 2010, a total of 146 ESCC patients received radical esophagectomy were retrospectively analyzed in our present study. PD-L1 expression and CD8+ T cell infiltration were evaluated through immunohistochemistry. The clinicopathological characteristics and survival were analyzed.

Results: There were 111 male and 35 female. The median age was 59.1 years (37-78 years). The positive rate of PD-L1 expression was 61.7%. The rate of high CD8+ T cell infiltration was 33%. No significant differences were found between clinicopathological features and PD-L1 expression or CD8+ T cell infiltration. PD-L1 expression was significantly associated with poor overall survival (P=0.010). However, CD8+ T cell infiltration was not a prognostic risk factor. Type of TIM was significantly associated with the prognosis of ESCC patients (P=0.021).

Conclusions: PD-L1 expression was an independent risk factor for the prognosis of ESCC patients. Immunotherapy may achieve promising outcomes in ESCC patients with type I TIM.

Comparative Molecular Analysis of Gastrointestinal Adenocarcinomas

We analyzed 921 adenocarcinomas of the esophagus, stomach, colon, and rectum to examine shared and distinguishing molecular characteristics of gastrointestinal tract adenocarcinomas (GIACs). Hypermutated tumors were distinct regardless of cancer type and comprised those enriched for insertions/deletions, representing microsatellite instability cases with epigenetic silencing of MLH1 in the context of CpG island methylator phenotype, plus tumors with elevated single-nucleotide variants associated with mutations in POLE. Tumors with chromosomal instability were diverse, with gastroesophageal adenocarcinomas harboring fragmented genomes associated with genomic doubling and distinct mutational signatures. We identified a group of tumors in the colon and rectum lacking hypermutation and aneuploidy termed genome stable and enriched in DNA hypermethylation and mutations in KRAS, SOX9, and PCBP1.

TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes in colorectal carcinomas

Inhibitors targeting the PDCD1 (programmed cell death 1, PD-1) immune checkpoint pathway have revolutionized cancer treatment strategies. The TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PDCD1 ligand 1, PD-L1) expression and tumor-infiltrating lymphocytes (TIL) has been proposed to predict response to immunotherapy. It remains to be determined clinical, pathological, and molecular features of TIME subtypes of colorectal cancer. Using 812 colon and rectal carcinoma cases from the Nurses' Health Study and Health Professionals Follow-up Study, we examined the association of tumor characteristics and survival outcomes with four TIME subtypes (TIME 1, CD274^low/TIL^absent; TIME 2, CD274^high/TIL^present; TIME 3, CD274^low/TIL^present; and TIME 4, CD274^high/TIL^absent). In survival analyses, Cox proportional hazards models were adjusted for potential confounders, including microsatellite instability (MSI) status, CpG island methylator phenotype (CIMP) status, LINE-1 methylation level, and KRAS, BRAF, and PIK3CA mutation status. TIME subtypes 1, 2, 3 and 4 had 218 (27%), 117 (14%), 103 (13%), and 374 (46%) colorectal cancer cases, respectively. Compared with TIL-absent subtypes (TIME 1 and 4), TIL-present subtypes (TIME 2 and 3) were associated with high-level MSI, high-degree CIMP, BRAF mutation, and higher amounts of neoantigens (p < 0.001). TIME subtypes were not significantly associated with colorectal cancer-specific or overall survival. In conclusion, TIL-present TIME subtypes of colorectal cancer are associated with high levels of MSI and neoantigen load, supporting better responsiveness to cancer immunotherapy. Further studies examining tumor molecular alterations and additional factors in the tumor microenvironment may inform development of immunoprevention and immunotherapy strategies.

Four distinct immune microenvironment subtypes in gastric adenocarcinoma with special reference to microsatellite instability

Introduction

Programmed death-ligand 1 (PD-L1) can be overexpressed in tumours other than Epstein-Barr virus (EBV)-positive (EBV⁺) or microsatellite instability-high (MSI-H) gastric cancer (GC) subtypes. We aimed to determine the tumour immune microenvironment (TME) classification of GC to better understand tumour-immune interactions and help patient selection for future immunotherapy with special reference to MSI-H.

Methods

Immunohistochemistry (IHC) for PD-L1 and CD8⁺ T cells in three distinct subtypes of GC (43 EBV⁺, 79 MSI-H and 125 EBV^-/MSS) were performed and analysed. In 66 MSI-H GC, mutation counts were compared with PD-L1 expression and survival of the patients.

Results

GC TME divided by PD-L1 IHC and tumour-infiltrating lymphocytes (TIL) measured by intratumoural CD8 density showed: (1) about 40% of GC are type I (PD-L1⁺/TIL⁺) consisting ~70% of MSI-H or EBV⁺ GC, and ~15% of EBV^-/microsatellite stable (MSS) GC patients show the best survival in both disease-free (HR 2.044) and overall survival (HR 1.993); this type would respond to a checkpoint blockade therapy; (2) almost 30% of GC are type II (PD-L1^-/TIL^-) with the worst survival; (3) approximately 10% of GC are type III (PD-L1⁺/TIL^-); and (4) up to 20% are type IV (PD-L1^-/TIL⁺) and, unexpectedly, ~25% of EBV⁺ or MSI-H GC are within this subtype. In MSI-H GC, frequent frameshift mutations were observed in ARID1A, RNF43, NF1, MSH6, BRD3, NCOA3, BCORL1, TNKS2 and NPM1 and the numbers of frameshift mutation correlated significantly with PD-L1 expression (P<0.05).

Discussion

GC can be classified into four TME types based on PD-L1 and TIL, and numbers of frameshift mutation correlate well with PD-L1 expression in MSI-H GC.

Intratumoural PD-L1 expression is associated with worse survival of patients with Epstein-Barr virus-associated gastric cancer

BACKGROUND

This study investigated the clinical relevance and prognostic impact of the overall expression of programmed cell death protein ligand-1 (PD-L1) and programmed cell death protein ligand-2 (PD-L2), in patients with Epstein-Barr virus-associated gastric cancer (EBVaGC).

METHODS

After reviewing 1318 consecutive cases of surgically resected or endoscopic submucosal dissected gastric cancers, the expression status of PD-L1 and PD-L2 in 120 patients with EBVaGC identified by EBV-encoded RNA in situ hybridisation was retrospectively analysed using immunohistochemistry (IHC). For each IHC marker, positivity was separately in intraepithelial tumour cells (iTu-) and immune cells in the tumour stroma area (str-).

RESULTS

Among 116 eligible patients, 57 (49.1%) and 66 patients (56.9%) were determined as iTu-PD-L1-positive and str-PD-L1-positive, respectively, whereas 23 (21.6%) and 45 patients (38.8%) were determined as iTu-PD-L2 positive and str-PD-L2 positive, respectively. Intraepithelial tumour cell PD-L1 positivity was found to be significantly associated with lymph node (LN) metastasis (P=0.012) and a poor disease-free survival (DFS) (P=0.032), yet not overall survival (P=0.482). In a multivariate analysis, iTu-PD-L1 positivity was independently associated with a poor DFS (P=0.006, hazard ratio=12.085). In contrast, str-PD-L2-positivity was related to a lower T category (P=0.003), absence of LN metastasis (P=0.032) and perineural invasion (P=0.028). Intraepithelial tumour cell and str-PD-L2 positivity showed a trend towards an improved DFS, although not significant (P=0.060 and P=0.073, respectively).

CONCLUSIONS

Intraepithelial tumour cells PD-L1 expression can be used to predict a poor outcome in patients with EBVaGC and can represent a rational approach for PD-1/PD-L pathway-targeted immunotherapy.