Diagnostic, prognostic, and predictive biomarkers in gastric cancer: from conventional to novel biomarkers

Gastric cancer is a major health concern worldwide. The survival rate of Gastric cancer greatly depends on the stage at which it is diagnosed. Early diagnosis is critical for improving survival outcomes. To improve the chances of early diagnosis, regular screening tests, such as an upper endoscopy or barium swallow, are recommended for individuals at a higher risk due to factors like family history or a previous diagnosis of gastric conditions. Biomarkers can be detected and measured using non-invasive methods such as blood tests, urine tests, breath analysis, or imaging techniques. These non-invasive approaches offer many advantages, including convenience, safety, and cost-effectiveness, making them valuable tools for disease diagnosis, monitoring, and research. Biomarker-based tests have emerged as a useful tool for identifying gastric cancer early, monitoring treatment response, assessing the recurrence risk, and personalizing treatment plans. In this current review, we have explored both classical and novel biomarkers for gastric cancer. We have centralized their potential clinical application and discussed the challenges in Gastric cancer research.

Peptides for microbe-induced cancers: latest therapeutic strategies and their advanced technologies

Cancer is a significant global health concern associated with multiple distinct factors, including microbial and viral infections. Numerous studies have elucidated the role of microorganisms, such as Helicobacter pylori (H. pylori), as well as viruses for example human papillomavirus (HPV), hepatitis B virus (HBV), and hepatitis C virus (HCV), in the development of human malignancies. Substantial attention has been focused on the treatment of these microorganism- and virus-associated cancers, with promising outcomes observed in studies employing peptide-based therapies. The current paper provides an overview of microbe- and virus-induced cancers and their underlying molecular mechanisms. We discuss an assortment of peptide-based therapies which are currently being developed, including tumor-targeting peptides and microbial/viral peptide-based vaccines. We describe the major technological advancements that have been made in the design, screening, and delivery of peptides as anticancer agents. The primary focus of the current review is to provide insight into the latest research and development in this field and to provide a realistic glimpse into the future of peptide-based therapies for microbe- and virus-induced neoplasms.

Evolving perspectives regarding the role of the PD-1/PD-L1 pathway in gastric cancer immunotherapy

Gastric cancer (GC) is an increasing global health problem and is one of the leading cancers worldwide. Traditional therapies, such as radiation and chemotherapy, have made limited progress in enhancing their efficacy for advanced GC. The development of immunotherapy for advanced GC has considerably improved with a deeper understanding of the tumor microenvironment. Immunotherapy using checkpoint inhibitors is a new therapeutic option that has made substantial advances in the treatment of other malignancies and is increasingly used in other clinical oncology treatments. Particularly, therapeutic antibodies targeting the programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway have been effectively used in the clinical treatment of cancer. Monoclonal antibodies blocking the PD-1/PD-L1 pathway have been developed for cancer immunotherapy to enhance T cell function to restore the immune response and represent a breakthrough in the treatment of GC. This review provides an outline of the progress of PD-1/PD-L1 blockade therapy and its expression characteristics and clinical application in advanced GC.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

Expression of Programmed Death Ligand1 (PD-L1) in Gastric Carcinoma (Histopathological and Immunohistochemical Study)

OBJECTIVES

To evaluate immunohistochemical expression of PD-L1 in cases of gastric adenocarcinoma. To correlate PD-L1 immuno-histochemical expression with other available clinico-pathological parameters such as age, sex, grade, stage, lymph node (L.N) metastasis and others.

MATERIAL AND METHODS

The present retrospective study retrieved the data and archived paraffin blocks of 60 cases of Gastric carcinoma. Immunohistochemical evaluation was done to assess the expressions of PD-L1 in the tumor cells (TC), tumor infiltrated lymphocytes (TILs) and combined positive score (CPS).

RESULTS

TC PD-L1 expression was detected in 56.7% of cases, TILs PD-L1 expression was detected in 53.3 % of cases and CPS PD-L1 expression was detected in 63.3% of case, with no statistically significant correlation with clinico-pathological parameters except TILs PD-L1 expression showed statistically significant correlation with positive TILs (P value ˂0.019).

CONCLUSION

Our findings supported the expression of PD-L1 by TC, TILs, and CPS in gastric cancer, with increased expression in a subpopulation of TILs rich in PD-L1 identifying them as potential targets for PD-1/PD-L1 therapy.

CagA-specific Gastric CD8+ Tissue-Resident T Cells Control Helicobacter pylori During the Early Infection Phase

BACKGROUND & AIMS

Infection with Helicobacter pylori strongly affects global health by causing chronic gastritis, ulcer disease, and gastric cancer. Although extensive research into the strong immune response against this persistently colonizing bacterium exists, the specific role of CD8⁺ T cells remains elusive.

METHODS

We comprehensively characterize gastric H pylori-specific CD8⁺ T-cell responses in mice and humans by flow cytometry, RNA-sequencing, immunohistochemistry, and ChipCytometry, applying functional analyses including T-cell depletion, H pylori eradication, and ex vivo restimulation.

RESULTS

We define CD8⁺ T-cell populations bearing a tissue-resident memory (T_RM) phenotype, which infiltrate the gastric mucosa shortly after infection and mediate pathogen control by executing antigen-specific effector properties. These induced CD8⁺ tissue-resident memory T cells (T_RM cells) show a skewed T-cell receptor beta chain usage and are mostly specific for cytotoxin-associated gene A, the distinctive oncoprotein injected by H pylori into host cells. As the infection progresses, we observe a loss of the T_RM phenotype and replacement of CD8⁺ by CD4⁺ T cells, indicating a shift in the immune response during the chronic infection phase.

CONCLUSIONS

Our results point toward a hitherto unknown role of CD8⁺ T-cell response in this bacterial infection, which may have important clinical implications for treatment and vaccination strategies against H pylori.

Anti-CD40L therapy prevents the formation of precursor lesions to gastric B-cell MALT lymphoma in a mouse model

Mucosa-associated lymphoid tissue (MALT) lymphoma is a B-cell tumour that develops over many decades in the stomachs of individuals with chronic Helicobacter pylori infection. We developed a new mouse model of human gastric MALT lymphoma in which mice with a myeloid-specific deletion of the innate immune molecule, Nlrc5, develop precursor B-cell lesions to MALT lymphoma at only 3 months post-Helicobacter infection versus 9-24 months in existing models. The gastric B-cell lesions in the Nlrc5 knockout mice had the histopathological features of the human disease, notably lymphoepithelial-like lesions, centrocyte-like cells, and were infiltrated by dendritic cells (DCs), macrophages, and T-cells (CD4+ , CD8+ and Foxp3+ ). Mouse and human gastric tissues contained immune cells expressing immune checkpoint receptor programmed death 1 (PD-1) and its ligand PD-L1, indicating an immunosuppressive tissue microenvironment. We next determined whether CD40L, overexpressed in a range of B-cell malignancies, may be a potential drug target for the treatment of gastric MALT lymphoma. Importantly, we showed that the administration of anti-CD40L antibody either coincident with or after establishment of Helicobacter infection prevented gastric B-cell lesions in mice, when compared with the control antibody treatment. Mice administered the CD40L antibody also had significantly reduced numbers of gastric DCs, CD8+ and Foxp3+ T-cells, as well as decreased gastric expression of B-cell lymphoma genes. These findings validate the potential of CD40L as a therapeutic target in the treatment of human gastric B-cell MALT lymphoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Helicobacter pylori infection and PD-L1 expression in gastric cancer: A meta-analysis

BACKGROUND

High expression of programmed death ligand-1 (PD-L1) has been related to good response to immunotherapy patients with gastric cancer (GC). However, the influence of Helicobacter pylori (HP) infection on PD-L1 expression in GC remains unknown. A meta-analysis was performed to evaluate the association between HP infection and PD-L1 expression in GC.

METHODS

Observational studies that investigated the relationship between HP infection and PD-L1 expression in patients with GC were obtained by search electronic databases, including PubMed, Embase, Cochrane's Library and Web of Science. A random-effect model incorporating the possible influence of between-study heterogeneity was used to pool the results.

RESULTS

Ten studies with 1870 patients with GC contributed to the meta-analysis. Pooled results showed that HP infection was significantly associated with the tumour expression of PD-L1 (odds ratio [OR]: 1.90, 95% confidence interval: 1.33-2.72, p < .001; I²  = 53%). Subgroup analyses showed that the association between HP infection and PD-L1 expression in GC was not significantly affected by sample size, methods for PD-L1 evaluation and quality score (p for subgroup analyses all >.05). However, a stronger association was observed in studies with higher prevalence of HP infection (≥35%, OR: 2.58) as compared with those with lower prevalence (<35%, OR: 1.45, p for subgroup difference = .04).

CONCLUSION

Helicobacter pylori infection in GC patients is associated with tumour expression of PD-L1, suggesting HP infection may be a predictor of good response to immunotherapy in GC.

Incorporating Immunotherapy in the Management of Gastric Cancer: Molecular and Clinical Implications

Simple Summary

Gastric cancer is one of the most common malignant tumours worldwide, with the fifth and third highest morbidity and mortality, respectively, of all cancers. Survival is limited, as most of the patients are diagnosed at an advanced stage, and are not suitable for surgery with a curative intent. Chemotherapy has only modestly improved patients’ outcomes and is mainly given with a palliative intent. Immunotherapy has improved overall survival of patients with gastric cancer, and has thus become a new standard of care in clinic. In this review we discuss the strong molecular rationale for the administration of immunotherapy in this disease and analyse the clinical data supporting its use.

Abstract

Gastric cancer has a median survival of 11 months, and this poor prognosis has not improved over the last 30 years. Recent pre-clinical data suggest that there is high tumour-related neoantigen expression in gastric cancer cells, suggesting that a clinical strategy that enhances the host’s immune system against cancer cells may be a successful approach to improve clinical outcomes. Additionally, there has been an increasing amount of translational evidence highlighting the relevance of PD-L1 expression in gastric cancer cells, indicating that PD-1/PD-L1 inhibitors may be useful. Several molecular subgroups of gastric cancer have been identified to respond with excellent outcomes to immunotherapy, including microsatellite instable tumours, tumours bearing a high tumour mutational burden, and tumours related to a chronic EBV infection. In gastric cancer, immunotherapy has produced durable responses in chemo-refractory patients; however, most recently there has been a lot of enthusiasm as several large-scale clinical trials highlight the improved survival noted from the incorporation of immunotherapy in the first line setting for advanced gastric cancer. Our review aims to discuss current pre-clinical and clinical data supporting the innovative role of immunotherapy in gastric cancer.

PD-L1 Up-Regulation in Prostate Cancer Cells by Porphyromonas gingivalis

Chronic inflammation is known to contribute to various human cancers. Porphyromonas gingivalis (P. gingivalis), is a gram-negative oral keystone pathogen that may cause severe periodontitis and expresses several virulence factors to affect the host immune system. Periodontitis is a chronic infectious disease that while progression, may cause loss of attachment and destruction of the tooth supporting tissues. Prostate cancer is one of the most common malignancies in men. Increasing evidence links periodontitis with prostate cancer, however the mechanisms explaining this relationship remain unclear. The aim of this study was to investigate the expression and signaling pathway of programmed death ligand 1 (PD-L1) in a prostate cancer cell line after infection with P. gingivalis and stimulation with P. gingivalis components to reveal the mechanism of tumor-induced immune evasion associated with bacterial infection in the tumor environment. Prostate cancer cells were infected with different concentrations of viable P. gingivalis and treated with different concentrations of heat-killed P. gingivalis and P. gingivalis cell components, including the total membrane fraction, inner membrane fraction, outer membrane fraction, cytosolic fraction and peptidoglycan (PGN). Chemical inhibitors were used to block different important molecules of signaling pathways to assess the participating signal transduction mechanisms. PD-L1 expression was detected by Western blot after 24 h of infection. PD-L1 was demonstrated to be upregulated in prostate cancer cells after infection with viable and with heat-killed P. gingivalis membrane fractions. Also isolated PGN induced PD-L1 up-regulation. The upregulation was mediated by the NOD1/NOD2 signaling pathway. No upregulation could be detected after treatment of the cells with P. gingivalis lipopolysaccharide (LPS). These results indicate, that chronic inflammatory disease can contribute to tumor immune evasion by modifying the tumor microenvironment. Thus, chronic infection possibly plays an essential role in the immune response and may promote the development and progression of prostate cancer.

Bacterial-Viral Interactions in Human Orodigestive and Female Genital Tract Cancers: A Summary of Epidemiologic and Laboratory Evidence

Infectious agents, including viruses, bacteria, fungi, and parasites, have been linked to pathogenesis of human cancers, whereas viruses and bacteria account for more than 99% of infection associated cancers. The human microbiome consists of not only bacteria, but also viruses and fungi. The microbiome co-residing in specific anatomic niches may modulate oncologic potentials of infectious agents in carcinogenesis. In this review, we focused on interactions between viruses and bacteria for cancers arising from the orodigestive tract and the female genital tract. We examined the interactions of these two different biological entities in the context of human carcinogenesis in the following three fashions: (1) direct interactions, (2) indirect interactions, and (3) no interaction between the two groups, but both acting on the same host carcinogenic pathways, yielding synergistic or additive effects in human cancers, e.g., head and neck cancer, liver cancer, colon cancer, gastric cancer, and cervical cancer. We discuss the progress in the current literature and summarize the mechanisms of host-viral-bacterial interactions in various human cancers. Our goal was to evaluate existing evidence and identify gaps in the knowledge for future directions in infection and cancer.

Implication of ARID1A Undercurrents and PDL1, TP53 Overexpression in Advanced Gastric Cancer

AT-rich interactive domain-containing protein 1A (ARID1A), TP53 and programmed cell death-ligand 1 (PDL1) are involved in several protein interactions that regulate the expression of various cancer-related genes involved in the progression of the cell cycle, cell proliferation, DNA repair, and apoptosis. In addition, gene expression analysis identified some common downstream targets of ARID1A and TP53. It has been established that tumors formed by ARID1A-deficient cancer cells exhibited elevated PDL1 expression. However, the aberrations in these molecules have not been studied in this population especially in Gastric Cancer (GC). In this backdrop we aimed to investigate the role of the ARID1A mutation and expression of ARID1A, TP53 and PDL1 genes in the etiopathogenesis of Gastric Cancer (GC) in the ethnic Kashmiri population (North India). The study included 103 histologically confirmed GC cases. The mutations, if any, in exon-9 of ARID1A gene was analysed by Polymerase Chain Reaction (PCR) followed by Sanger sequencing. The mRNA expression of the ARID1A, TP53 and PDL1 genes was analysed by Quantitative real time-PCR (qRT-PCR). We identified a nonsense mutation (c.3219; C > T) in exon-9 among two GC patients (∼2.0%), which introduces a premature stop codon at protein position 1073. The mRNA expression of the ARID1A, TP53 and PDL1 gene was significantly reduced in 25.3% and elevated in 47.6 and 39.8% of GC cases respectively with a mean fold change of 0.63, 2.93 and 2.43. The data revealed that reduced mRNA expression of ARID1A and elevated mRNA expression of TP53 and PDL1 was significantly associated with the high-grade and advanced stage of cancer. Our study proposes that ARAD1A under-expression and overexpression of TP53 and PDL1 might be crucial for tumor progression with TP53 and PDL1 acting synergistically.

Tissue Pathogens and Cancers: A Review of Commonly Seen Manifestations in Histo- and Cytopathology

Tissue pathogens are commonly encountered in histopathology and cytology practice, where they can present as either benign mimickers of malignancy or true malignancies. The aim of this review is to provide a timely synthesis of our understanding of these tissue pathogens, with an emphasis on pertinent diagnostic conundrums associated with the benign mimickers of malignancy that can be seen with viral infections and those which manifest as granulomas. The oncogenic pathogens, including viruses, bacteria, and parasites, are then discussed with relationship to their associated malignancies. Although not exhaustive, the epidemiology, clinical manifestations, pathogenesis, and histological findings are included, along with a short review of emerging therapies.

The crosstalk between H. pylori virulence factors and the PD1:PD-L1 immune checkpoint inhibitors in progression to gastric cancer

BACKGROUND

The progression to gastric cancer has been linked to chronic infection with Helicobacter pylori (H. pylori). Immune checkpoint inhibitors (programmed cell death -1, PD-1; programmed cell death -ligand 1, PD-L1) have a role in cancer immune escape. The relationship between H. pylori virulence factors with PD-1, PD-L1 T helper 1 (Th1), T helper 17 (Th17), and regulatory T cell (Treg) response genes, has not been thoroughly investigated in the development of gastric cancer. Therefore, we evaluated how H. pylori virulence factors influence the expression levels of immune-related genes in the development of gastric immunopathology.

METHODS

A total of 92 gastric tissues of normal controls and patients with gastritis, gastric ulcer, and gastric cancer were examined for the expression of immune-checkpoint inhibitor genes (PD-1 PD-L1), Th1 (interferon- γ, IFN-γ), Th17 (interleukin- 17, IL-17, Retinoic-acid-receptor- related orphan nuclear receptor gamma t, RORγ-t), and Treg (Forkhead box P3, FOXP3) response genes with quantitative real-time PCR (qRT-PCR). Furthermore, correlation of H. pylori virulence factors' (cytotoxin-associated gene A, cagA; vacuolating cytotoxin gene A, vacA (s1,s2,m1,m2); blood group antigen-binding adhesin gene A, babA, duodenal ulcer promoting gene A, dupA; the putative neuraminyllactose-binding hemagglutinin homolog, hpaA; neutrophil-activating protein A napA; outer inflammatory protein A, oipA; urease A, ureA; and urease B, ureB) genotypes with a degree of inflammation and density of H. pylori were investigated. Next, the relationship between H. pylori virulence factors and immune-checkpoint inhibitor genes, and T-cell response genes was evaluated. Eventually, a decision tree model was developed to determine the clinical outcome of patients using expression data.

RESULTS

The intensity of PD-1 and PD-L1 mRNA expression was increased significantly in gastric tissue of patients with gastric ulcer (PD-1: 2.3 fold, p=0.01; PD-L1: 2.1 fold, p=0.004), and gastric cancer (PD-1: 2 fold, p= 0.04; PD-L1: 1.8 fold, p=0.05) compared with control subjects. Also, PD-1: PD-L1 expression was significantly higher in patients with gastritis, who were infected with a marked density of H. pylori compared with its mildly infected counterparts. Furthermore, a novel negative correlation was found between PD-1 (r= -0.43) and PD-L1 (r= -0.42) with FOXP3 in patients with gastritis. CagA-positive H. pylori strain's negative association with PD-L1 expression (r=-0.34) was detected in patients with gastritis. Interestingly, PD-1 mRNA expression correlated positively with vacA s2/m2, in gastritis (r=0.43) and ulcer (r=0.43) patients. Furthermore, PD-1: PDL1 expression negatively correlated with vacA m1/m2 (r=-0.43 for PD-1; r=-0.38 for PD-L1) in gastritis patients. Moreover, an inverse correlation of PDL1 was present with vacA m1 (r=0.52) and vacA s1/m1 (r=0.46) versus vacA m2 (r=-0.44) and vacA m1 (r=0.52) and vacA s1/m2 (r=-0.14) in ulcer patients, respectively. Also, a correlation of vacA m2 (r=-0.47) and vacA s1/s2 (r= 0.45) with PD-1 was detected in ulcer patients. In addition, a novel negative correlation between FOXP3 mRNA levels and napA was shown in patients with gastritis and ulcer (r=-0.59). Finally, a computer-based model that was developed showed that knowing the expression levels of PD-L1, RORγ-t, and vacA s1/m2 would be useful to detect the clinical outcome of a patient.

CONCLUSION

Our results suggested that PD-1:PD-L1 immune checkpoint inhibitors were increased in gastric pre-cancerous lesions that progress to gastric cancer. Herein, we report the relationship between H. pylori virulence factors and expression of host immune checkpoint inhibitors for diagnostic prediction of gastric malignancies using computer-based models.

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

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

Targeted Nano-Drug Delivery of Colchicine against Colon Cancer Cells by Means of Mesoporous Silica Nanoparticles

Antimitotics are important anticancer agents and include the natural alkaloid prodrug colchicine (COL). However, a major challenge of using COL as an anticancer drug is its cytotoxicity. We developed a novel drug delivery system (DDS) for COL using mesoporous silica nanoparticles (MSNs). The MSNs were functionalized with phosphonate groups, loaded with COL, and coated with folic acid chitosan-glycine complex. The resulting nanoformulation, called MSNsPCOL/CG-FA, was tested for action against cancer and normal cell lines. The anticancer effect was highly enhanced for MSNsPCOL/CG-FA compared to COL. In the case of HCT116 cells, 100% inhibition was achieved. The efficiency of MSNsPCOL/CG-FA ranked in this order: HCT116 (colon cancer) > HepG2 (liver cancer) > PC3 (prostate cancer). MSNsPCOL/CG-FA exhibited low cytotoxicity (4%) compared to COL (~60%) in BJ1 normal cells. The mechanism of action was studied in detail for HCT116 cells and found to be primarily intrinsic apoptosis caused by an enhanced antimitotic effect. Furthermore, a contribution of genetic regulation (metastasis-associated lung adenocarcinoma transcript 1 (MALAT 1), and microRNA (mir-205)) and immunotherapy effects (angiopoietin-2 (Ang-2 protein) and programmed cell death protein 1 (PD-1) was found. Therefore, this study shows enhanced anticancer effects and reduced cytotoxicity of COL with targeted delivery compared to free COL and is a novel method of developing cancer immunotherapy using a low-cost small-molecule natural prodrug.

Spatiotemporal Changes in Checkpoint Molecule Expression

Immune checkpoint inhibitors (ICIs), particularly PD-1/PD-L1 blockade, have led to therapeutic breakthrough in patients with advanced malignancy, covering the lung, breast, gastrointestinal, head and neck, urinary system, lymphoma, and solid tumor harboring MSI/dMMR. In certain cancer types, the expression level of immune checkpoint molecule will be required if the immune-based approaches are considered, especially the PD-L1 expression. However, in other types, survival benefit has been proven regardless of PD-L1 expression. It raises a question of how to select patients for immune therapy and whether the expression of immune checkpoint molecules will be optimal biomarkers. Before answering this question, a comprehensive map for the expression of immune checkpoint molecules is needed. In this chapter, we describe our current knowledge on the spatiotemporal changes in the expression of checkpoint molecules. We discuss the different frequencies of expression depending on tumor types and stages, the different patterns between primary and metastatic tumors, as well as the change of expression before and after treatment. The expression of PD-L1 has been most studied, but the threshold that separate "positive" and "negative" PD-L1 expressions and the consistency of testing platform remain under debate. Better understanding on the tumor microenvironment and expression of checkpoint molecules will help to identify patients who will benefit from checkpoint blockade therapy.

Current and Future Aspects of Immunotherapy for Esophageal and Gastric Malignancies

Esophagogastric (EG) cancer has a poor prognosis despite the use of standard therapies, such as chemotherapy and biologic agents. Recently, immune checkpoint inhibitors (ICIs) have been introduced as treatments for EG cancer; nivolumab and pembrolizumab have been approved in the United States and Europe to treat advanced EG cancer. Other ICIs, such as avelumab, durvalumab, ipilimumab, and tremelimumab, have been evaluated in several trials, although their roles are still not established in clinical practice. In addition, preclinical evidence suggests that combining an ICI with a tumor-targeting antibody can result in greater antitumor effects in metastatic EG cancer. There are not yet validated predictive biomarkers to identify which patients will respond best to ICI treatment. PD-L1 expression may predict intensity of response, although PD-L1-negative patients can still respond to ICIs. Despite differences in PD-L1 expression between Asian and non-Asian populations, no geographic differences in rates of treatment-related or immune-mediated/infusion-related adverse events have been reported. Also, several trials are currently evaluating combinations of ICIs, standard chemotherapy, and biologic agents as well as novel biomarkers to improve treatments and outcomes. Our review will address the current use of and evidence for ICIs for advanced EG cancer treatment and future trends in this area for clinical practice.