Increased PD-1 expression on CD4+ and CD8+ T cells is involved in immune evasion in gastric cancer

Investigating T Cell Immune Dynamics and IL-6's Duality in a Microfluidic Lung Tumor Model

Interleukin 6 (IL-6), produced by immune cells, is crucial in promoting T cell trafficking to infection and inflammation sites, influencing various physiological and pathological processes. Concentrations of IL-6 and other cytokines and chemokines can influence T cell differentiation and activation. Understanding the dual faces of IL-6 within the tumor microenvironment is crucial to understanding its role. A flow-based microsystem was designed to investigate CD4+ T cell activation in response to different IL-6 gradients in an under-control 3D culture. The study found that cancer cells' response to varying IL-6 concentrations was dynamic and dose-sensitive, with immune cell migration rates showing sensitivity to the IL-6 gradient. A549 cell expansion increases gradually and time-dependently with 50 ng of IL-6, while Jurkat cell migration follows a time-dependent pattern. However, when a total of 100 ng IL-6 concentration is applied, A549 cells expand rapidly, potentially influencing Jurkat cell migration. Jurkat cell mobility is lower, possibly due to increased A549 cell presence and heightened cell-cell interactions. Different IL-6 concentration gradients can modulate the expression of some CD markers like CD69 and programed cell death protein 1 in CD4+ T cells, suggesting that IL-6 concentration gradients affect immune cell phenotypes. This suggests that IL-6 plays a crucial role in activating T helper cells and may be involved in the later phases of inflammation. Also, the increased levels of IFN-γ and TNF-α highlight IL-6's impact on T cell inflammatory response. This study emphasizes the intricate effects of IL-6 on T cell activation, phenotype, cytokine production, and phenotypic heterogeneity, providing valuable insights into immune response modulation in an experimental setting.

Impact of oxaliplatin and trastuzumab combination therapy on tumor markers and T lymphocyte subsets for advanced gastric cancer

BACKGROUND

Advanced gastric cancer (AGC) remains a challenging malignancy with poor prognosis. The combination of oxaliplatin and trastuzumab has shown promising results in AGC treatment. This study aimed to investigate the effects of oxaliplatin and trastuzumab combination therapy on serum tumor markers and T lymphocyte subsets in patients with AGC and to explore their potential as predictive biomarkers for treatment response.

AIM

To investigate the impact of oxaliplatin and trastuzumab combination therapy on serum markers and T cell subsets in patients with AGC.

METHODS

This prospective study enrolled 60 patients with AGC. All patients received oxaliplatin (130 mg/m2, every 3 weeks) and trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) for six cycles. Serum carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4) were measured before and after treatment. T-lymphocyte subsets, including CD3+, CD4+, CD8+, and CD4+ /CD8+ ratios, were also evaluated. The clinical response was assessed using the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

After six cycles of treatment, the CEA, CA19-9, and CA72-4 serum levels significantly decreased compared to baseline levels (P < 0.001). The percentages of CD3+ and CD4+ T lymphocytes increased significantly (P < 0.05), whereas the percentage of CD8+ T lymphocytes decreased (P < 0.05). The CD4+/CD8+ ratio also significantly increased after treatment (P < 0.05). Patients with a higher decrease in serum tumor markers (≥ 50% reduction) and a higher increase in CD4+/CD8+ ratio (≥ 1.5-fold) showed better clinical response rates (P < 0.05).

CONCLUSION

Oxaliplatin and trastuzumab combination therapy effectively reduced serum tumor marker levels and modulated T lymphocyte subsets in patients with AGC. Combination therapy not only has a direct antitumor effect, but also enhances the immune response in patients with AGC. Serum tumor markers and T lymphocyte subsets may serve as potential predictive biomarkers for treatment response in patients with AGC receiving combination therapy.

Combination of IFN-gamma with STING agonist and PD-1 immune checkpoint blockade: a potential immunotherapy for gastric cancer

Suppression of the cGAS-STING pathway is an immune escape mechanism in cancer cells. The critical role of this pathway in gastric cancer (GC) is not fully understood. Herein, we evaluated the effect of the interferon-gamma (IFN-gamma), STING agonist, PD-1 immune checkpoint blockade, and their combination on the cGAS-STING pathway in GC. Expression of cGAS and STING in tumor tissue samples and adjacent normal tissue (ANT) biopsies of fifty new GC patients was evaluated by quantitative real-time PCR (qRT-PCR). Moreover, cGAS and STING expression levels were examined in Peripheral Blood Mononuclear Cells (PBMC) samples of forty GC patients and twenty-five healthy subjects. The apoptosis rate of cancer cells was analyzed by Annexin V-FITC/PI. Cell proliferation was measured by the BrdU assay. Also, IFN-β levels were evaluated in the supernatants of the treated groups. The cGAS expression was decreased in patients with distant metastasis. Co-cultures treated with IFN-gamma showed an elevated level of cGAS and STING expressions in PBMC and cancer cells. The rate of apoptosis increased in all the treatment groups. In addition, the rate of proliferation in PBMCs increased in different treated groups. The main role of PBMCs in cytotoxicity was determined by a comparative analysis of the viability of cells treated with all treatments, both with and without PBMCs. The production of IFN-β was elevated in all treated groups. The current study suggests that a combination therapy using IFN-gamma, STING agonist, and anti-PD-1 antibody can provide a promising approach to the treatment of GC.

Expression characteristics of peripheral lymphocyte programmed death 1 and FoxP3+ Tregs in gastric cancer during surgery and chemotherapy

BACKGROUND

Programmed death 1 (PD-1) and CD4+CD25+FoxP3+ expression in peripheral blood T-cells has been previously reported in various types of cancer. However, the specific variation tendency during surgery and chemotherapy, as well as their relationship in gastric cancer patients, still remain unclear. Understanding this aspect may provide some novel insights for future studies on tumor recurrence and tumor immune escape, and also serve as a reference for determining the optimal timing and dose of clinical anti-PD-1 antibodies.

AIM

To observe and analyze the expression characteristics of peripheral lymphocyte PD-1 and FoxP3+ regulatory T cells (FoxP3+ Tregs) before and after surgery or chemotherapy in gastric cancer patients.

METHODS

Twenty-nine stomach cancer patients undergoing chemotherapy after a D2 gastrectomy provided 10 mL peripheral blood samples at each phase of the perioperative period and during chemotherapy. This study also included 29 age-matched healthy donors as a control group. PD-1 expression was detected on lymphocytes, including CD4+CD8+CD45RO+, CD4+CD45RO+, and CD8+CD45RO+ lymphocytes as well as regulatory T cells.

RESULTS

We observed a significant increase of PD-1 expression on immune subsets and a larger number of FoxP3+ Tregs in gastric cancer patients (P < 0.05). Following D2 gastrectomy, peripheral lymphocytes PD-1 expression and the number of FoxP3+ Tregs notably decrease (P < 0.05). However, during postoperative chemotherapy, we only observed a decrease in PD-1 expression on lymphocytes in the CD8+CD45RO+ and CD8+CD45RO+ populations. Additionally, linear correlation analysis indicated a positive correlation between PD-1 expression and the number of CD4+CD45RO+FoxP3high activated Tregs (aTregs) on the total peripheral lymphocytes (r = 0.5622, P < 0.0001).

CONCLUSION

The observed alterations in PD-1 expression and the activation of regulatory T cells during gastric cancer treatment may offer novel insights for future investigations into tumor immune evasion and the clinical application of anti-PD-1 antibodies in gastric cancer.

Progress of PD-1/PD-L1 signaling in immune response to liver transplantation for hepatocellular carcinoma

Primary liver cancer is one of the most common malignant tumors in China. The vast majority of primary liver cancer are hepatocellular carcinoma. Due to its high incidence and mortality from HCC, HCC has always been a feared type of cancer. Liver transplantation, as one of the important means to treat advanced liver cancer, has brought new hope to patients. However, as patients have been in a state of immunosuppression after liver transplantation, these patients face new problems of HCC recurrence and metastasis. A increasing number of studies have proved that blocking the PD-1/PD-L1 signaling pathway and restoring the immune killing inhibition of T cells can produce better therapeutic effects on tumors and chronic infectious diseases. As a promising treatment in the field of tumor immunotherapy, PD-1/PD-L1 inhibitors have achieved important results in liver cancer patients, but their application in liver transplantation patients is still highly controversial. This paper will introduce the mechanism of action of PD-1/PD-L1 signaling pathway and the current basic and clinical studies of PD-1/PD-L1 signaling pathway associated with immune response in HCC transplantation.

Advances in translational therapy for locally advanced gastric cancer

Translational therapy refers to a combination of chemotherapy, radiotherapy, targeted therapy, and immunotherapy for patients with advanced gastric cancer who are initially unable to undergo R0 resection. This treatment can achieve partial or complete remission of the unresectable tumors to meet the criteria for R0 resection, thus enabling the patients to prolong their survival time and improve their quality of life. In gastric cancer, translational therapy has been tried and improved. At present, there are a large number of patients with locally advanced gastric cancer in China, and the selection of suitable patients for translational therapy to prolong objective survival and improve survival quality is one of the hot spots in the field of gastric cancer research.

PD-1 and PD-L1 Expression Levels as a Potential Biomarker of Chronic Rhinosinusitis and Head and Neck Cancers

Inflammation is an etiological factor of various chronic diseases contributing to more than 50% of worldwide deaths. In this study, we focus on the immunosuppressive role of the programmed death-1 (PD-1) receptor and its ligand (PD-L1) in inflammatory-related diseases, including chronic rhinosinusitis and head and neck cancers. The study included 304 participants. Of this number, 162 patients had chronic rhinosinusitis with nasal polyps (CRSwNP), 40 patients had head and neck cancer (HNC) and there were 102 healthy subjects. The expression level of the PD-1 and PD-L1 genes in the tissues of the study groups was measured by qPCR and Western blot methods. The associations between the age of the patients and the extent of disease and genes' expression were evaluated. The study showed a significantly higher mRNA expression of PD-1 and PD-L1 in the tissues of both the CRSwNP and HNC patient groups compared to the healthy group. The severity of CRSwNP significantly correlated with the mRNA expression of PD-1 and PD-L1. Similarly, the age of the NHC patients influenced PD-L1 expression. In addition, a significantly higher level of PD-L1 protein was noticed also for both the CRSwNP and HNC patient groups. The increased expression of PD-1 and PD-L1 may be a potential biomarker of inflammatory-related diseases, including chronic rhinosinusitis and head and neck cancers.

Alterations in Hepatocellular Carcinoma-Specific Immune Responses Following Hepatitis C Virus Elimination by Direct-Acting Antivirals

Direct-acting antivirals (DAAs) have recently revolutionized the eradication of chronic hepatitis C virus (HCV) infection. However, the effects of DAAs on the development of hepatocellular carcinoma (HCC) remain unknown. Therefore, the present study aimed to investigate immune responses to HCC influenced by DAAs in HCV-infected patients and elucidate the underlying mechanisms. We compared immune responses to 19 different HCC-related tumor-associated antigen (TAA)-derived peptides and host immune cell profiles before and 24 weeks after a treatment with DAAs in 47 HLA-A24-positive patients. The relationships between the different immune responses and phenotypic changes in immune cells were also examined. The treatment with DAAs induced four types of immune responses to TAAs and markedly altered host immune cell profiles. Prominently, reductions in the frequencies of PD-1+CD4+ and PD-1+CD8+ T cells by DAAs were associated with enhanced immune responses to TAAs. The HCV F protein was identified as contributing to the increased frequency of PD-1+ T cells, which may be decreased after eradication by DAAs. DAAs altered the immune responses of patients to HCC by decreasing the frequency of PD-1-expressing CD4+ and CD8+ T cells.

Development of a human phage display-derived anti-PD-1 scFv antibody: an attractive tool for immune checkpoint therapy

Background

The PD-1 checkpoint pathway plays a major role in tumor immune evasion and the development of the tumor microenvironment. Clinical studies show that therapeutic antibodies blocking the PD-1 pathway can restore anti-tumor or anti-virus immune responses by the reinvigoration of exhausted T cells. Because of the promising results of anti-PD-1 monoclonal antibodies in cancer treatment, autoimmune disorders, and infectious diseases, the PD-1 has emerged as an encouraging target for different diseases.

Results

In the present study, we employed a human semi-synthetic phage library for isolation of some scFvs against the extracellular domain of PD-1 protein by panning process. After the panning, a novel anti-PD-1 scFv (SS107) was found that exhibited specific binding to PD-1 antigen and stimulated Jurkat T cells. The selected anti-PD-1 scFv could restore the production of IL-2 and IFN-γ by Jurkat T cells that were co-cultured with PD-L1 positive tumor cells.

Conclusion

This anti-PD-1 scFv with high specificity and the ability to reactivate exhausted T cells has the potential to be developed as an anti-cancer agent or to be used in combination with other therapeutic approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-022-00752-8.

Effect of operation introducing hyperthermic intraperitoneal chemotherapy on cellular immune function in patients with adenocarcinoma of esophagogastric junction

BACKGROUND

This study aims to take a closer look at the effect of radical operation, introducing hyperthermic intraperitoneal chemotherapy, on cellular immunity for patients suffering from AEG.

METHODS

252 cases of patients with advanced AEG were randomly divided into two distinct groups, namely, a HIPEC group and a surgery only group. T lymphocyte subsets, CD4 + CD25 + T cells, which are known as the regulatory T cells, and the programmed cell death protein 1 (PD-1) contained in T cells were detected by PREO and POD 9.

RESULTS

The two groups differed drastically in terms of the proportion of T lymphocyte subsets and CD4 + CD25 + , CD4 + PD-1 + , CD8 + PD-1 + T cells, based on the observation on POD 9. The percentage of CD3 + , CD3 + CD4 + T cells identified in the HIPEC group outnumbered the percentage in the surgery only group (P < 0.01), whereas the quantity of CD3 + CD8 + , CD4 + CD25 + , CD4 + PD-1 + , CD8 + PD-1 + T cells in the former group was much lower than that of the latter group (P < 0.05).

CONCLUSION

HIPEC, following the operation on patients with advanced AEG, is capable of improving the cellular immune function and facilitating the release of a cellular immunosuppressive state.

The Positive and Negative Immunoregulatory Role of B7 Family: Promising Novel Targets in Gastric Cancer Treatment

Gastric cancer (GC), with a heterogeneous nature, is the third leading cause of death worldwide. Over the past few decades, stable reductions in the incidence of GC have been observed. However, due to the poor response to common treatments and late diagnosis, this cancer is still considered one of the lethal cancers. Emerging methods such as immunotherapy with immune checkpoint inhibitors (ICIs) have transformed the landscape of treatment for GC patients. There are presently eleven known members of the B7 family as immune checkpoint molecules: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1, CD274), B7-DC (PDCD1LG2, PD-L2, CD273), B7-H2 (B7RP1, ICOS-L, CD275), B7-H3 (CD276), B7-H4 (B7x, B7S1, Vtcn1), B7-H5 (VISTA, Gi24, DD1α, Dies1 SISP1), B7-H6 (NCR3LG1), B7-H7 (HHLA2), and Ig-like domain-containing receptor 2 (ILDR2). Interaction of the B7 family of immune-regulatory ligands with the corresponding receptors resulted in the induction and inhibition of T cell responses by sending co-stimulatory and co-inhibitory signals, respectively. Manipulation of the signals provided by the B7 family has significant potential in the management of GC.

Immune normalization strategy against suboptimal health status: safe and efficacious therapy using mixed-natural killer cells

"Immune normalization" has emerged as a new paradigm in immunotherapy, which is proposed in cancer patients instead of conventional "immune-enhancement" therapy. Immune normalization may also be implemented in cancer prevention of "sub-healthy" individuals. We established in vitro cultured mixed-natural killer (NKM) cells to achieve immune normalization. The in vitro cytotoxicity of NKM cells was tenfold higher than that of peripheral blood mononuclear cells (PBMCs). The cytotoxicity of NKM cells was negatively correlated with the proportion of T-helper cells (cluster of differentiation: CD3+CD4+ T), and positively correlated with the proportion of NK cells (especially CD56^brightCD16^bright NK cells). Then, we defined "sub-healthy individuals" after measuring Programmed cell death protein-1 (PD-1) expression in PBMCs from 95 donors aged > 50 years. Furthermore, we evaluated the potential clinical application of NKM-cell therapy in 11 patients with malignant lymphoma, one patient with pancreatic cancer, and four sub-healthy individuals. NKM-cell therapy elicited good tolerance and side-effects were not found. In sub-healthy individuals, the proportion of CD3⁺PD-1⁺ T cells and CD3⁺CD8⁺PD-1⁺ T cells was reduced significantly after NKM-cell treatment. We demonstrated that a new method using NKM cells was safe and efficacious as adjuvant treatment for cancer patients as well as therapy for sub-healthy individuals. Normalization of the peripheral immune system through NKM-cell therapy could expand its scope of application in different disorders.

Role of CD8+ T lymphocyte cells: Interplay with stromal cells in tumor microenvironment

CD8+ T lymphocytes are pivotal cells in the host response to antitumor immunity. Tumor-driven microenvironments provide the conditions necessary for regulating infiltrating CD8+ T cells in favor of tumor survival, including weakening CD8+ T cell activation, driving tumor cells to impair immune attack, and recruiting other cells to reprogram the immune milieu. Also in tumor microenvironment, stromal cells exert immunosuppressive skills to avoid CD8+ T cell cytotoxicity. In this review, we explore the universal function and fate decision of infiltrated CD8+ T cells and highlight their antitumor response within various stromal architectures in the process of confronting neoantigen-specific tumor cells. Thus, this review provides a foundation for the development of antitumor therapy based on CD8+ T lymphocyte manipulation.

Lysosome activable polymeric vorinostat encapsulating PD-L1KD for a combination of HDACi and immunotherapy

PD-1/PD-L1 blocking therapy has become one of the most promising methods in the field of tumor treatment. However, it encounters the challenge of immune escape due to the exhaustion of T cells. Studies have shown that the epigenetic regulation drug histone deacetylase inhibitor (HDACi) may be able to reverse exhausted T cells by changing the epigenetic transcription program. Therefore, the combination of epigenetic therapy and PD-1/PD-L1 blockade therapy is expected to reverse the immune escape, whereas the overriding goal should aim at the spontaneous release and synergy of PD-1/PD-L1 blocking siRNA and HDACi. In this study, we develop PDDS{polyethylene glycol-b-asparaginate(diethylenetriamine-vorinostat), (PEG-b-P[Asp(DET-SAHA)_n] PPDS)}encapsulating siRNA-PD-L1to provide micelles siRNA-PD-L1-loaded micelles (siRNA@PPDS). Transmission electron microscope (TEM) images demonstrate that siRNA@PPDS micelles presented spherical morphology with a size of about 120 nm; hydrodynamic data analysis indicates pH sensitivity of siRNA@PPDS micelles. The experiments reveal that siRNA@PPDS micelles could be well uptaken by the tumor cells to silence the expression of PD-L1 protein in a dose-dependent manner; compared with the free SAHA, the SAHA-loaded micelles PPDS show higher cytotoxicity to induce tumor cell apoptosis and block cell cycle in G1 phase on melanoma-bearing mice, siRNA@PPDS has shown outstanding inhibition of tumor growth and pulmonary metastasis. By comprehensively activating the immune system, lysosome activable polymeric vorinostat encapsulating PD-L1KD for the combination therapy of PD-L1-KD and HDACIs can be an effective strategy to reverse the unresponsiveness of immune checkpoint inhibitors and a promising treatment to inhibit tumor growth, recurrence, and metastasis in clinic.

The Crosstalk between Microbiome and Immune Response in Gastric Cancer

Gastric cancer is the end result of a complex interplay between host genetics, environmental factors, and microbial factors. The link between gut microbiome and gastric cancer has been attributed to persistent activation of the host's immune system by gut microbiota. The end result of this dysregulated interaction between host epithelium and microbes is a state of chronic inflammation. Gut bacteria can promote anti-tumor immune responses through several mechanisms. These include triggering T-cell responses to bacterial antigens that can cross-react with tumor antigens or cause tumor-specific antigen recognition; engagement of pattern recognition receptors that mediate pro-immune or anti-inflammatory effects or via small metabolites that mediate systemic effects on the host. Here we review the role of the gut microbiome including H. pylori and non-H. pylori gastric bacteria, the immune response, and immunotherapy using checkpoint inhibitors. We also review the evidence for cross talk between the gut microbiome and immune response in gastric cancer.

PD-1 does not mark tumor-infiltrating CD8+ T cell dysfunction in human gastric cancer

Background

Overexpression of programmed cell death protein 1 (PD-1) is linked to CD8+ T cell dysfunction and contributes to tumor immune escape. However, the prevalence and functional regulations of PD-1 expression on CD8+ T cells in human gastric cancer (GC) remain largely unknown.

Methods

Flow cytometry was performed to analyze the level, phenotype, functional and clinical relevance of PD-1+CD8+ T cells in GC patients. Peripheral blood CD8+ T cells were purified and subsequently exposed to culture supernatants from digested primary GC tumor tissues (TSN) in vitro for PD-1 expression and functional assays. Tumor responses to adoptively transferred TSN-stimulated CD8+ T cells or to the TSN-stimulated CD8+ T cell transfer combined with an anti-PD-1 antibody injection were measured in an in vivo xenograft mouse model.

Results

GC patients’ tumors showed a significantly increased PD-1+CD8+ T cell infiltration. However, these GC-infiltrating PD-1+CD8+ T cells showed equivalent function to their PD-1−CD8+ counterparts and they did not predict tumor progression. High level of transforming growth factor-β1 (TGF-β1) in tumors was positively correlated with PD-1+CD8+ T cell infiltration, and in vitro GC-derived TGF-β1 induced PD-1 expression on CD8+ T cells via Smad3 signaling, whereas Smad2 signaling was involved in GC-derived TGF-β1-mediated CD8+ T cell dysfunction. Furthermore, GC-derived TGF-β1-mediated CD8+ T cell dysfunction contributed to tumor growth in vivo that could not be attenuated by PD-1 blockade.

Conclusions

Our data highlight that GC-derived TGF-β1 promotes PD-1 independent CD8+ T cell dysfunction. Therefore, restoring CD8+ T cell function by a combinational PD-1 and TGF-β1 blockade might benefit future GC immunotherapy.

Intracellular accumulation of PD-1 molecules in circulating T lymphocytes in advanced malignant melanoma: an implication for immune evasion mechanism

BACKGROUND

The blockade of cell surface PD-1 (_(sur)PD-1) by monoclonal antibodies, represented by nivolumab, provides the strategy to treat advanced malignant melanoma (AMM). The intracellular presence of PD-1 molecules have been reported in some T cell subsets, however, their kinetic association with those expressed on the cell surface, let alone their significance in antitumor immunity has been ill-investigated.

METHODS

Intracellular PD-1 expression status in T cell subsets in AMM cases during nivolumab administration was chronologically characterized. The kinetics of PD-1 molecules within AMM-derived T cells was assessed in vitro in conjunction with their functional properties.

RESULTS

Increase in _(sur)PD-1 and intracellular PD-1 (_(int)PD-1⁺) expression was characteristic for AMM T cells. After short-term culture, virtually _(sur)PD-1^- nivolumab-treated AMM T cells restore _(sur)PD-1 expression, which could not be explained by the detachment of nivolumab from PD-1 epitopes alone. The blockade of trans-Golgi network resulted in the decrease in the extent of _(sur)PD-1 recovery, suggesting the translocation of accumulated _(int)PD-1 to the cell surface. Antigen-specific PD-1⁺ T cells significantly increased in _(int)PD-1⁺ cells after treatment. In addition, a surge in _(int)PD-1⁺CD4⁺ T cells was observed prior to the emergence of skin rash as an immune-related adverse event (irAE).

CONCLUSIONS

Accumulated _(int)PD-1 in T cells may contribute to enhanced immune evasion in AMM. Evaluation of intracellular PD-1 expression would be useful for better management of nivolumab-treated AMM patients in view of predicting treatment response and the incidence of irAE. Our findings further support the necessity of periodical administration of nivolumab for treating AMM.

Predicting treatment response of patients with extranodal natural killer/T-cell lymphoma based on levels of PD-L1 mRNA and soluble PD-L1

Appropriate biomarkers may help predict patient response to treatment for extranodal natural killer/T‐cell lymphoma (ENKTL), a subtype of non‐Hodgkin's lymphoma in China. Programmed cell death receptor 1 (PD‐1) and its ligand (PD‐L1) have been investigated in various tumors. However, few studies have addressed expression of PD‐1/PD‐L1 in peripheral blood of ENKTL patients. To identify novel peripheral blood biomarkers for diagnosis and treatment of ENKTL, we retrospectively examined 89 healthy volunteers, 49 patients with ENKTL and 74 patients with diffuse large B‐cell lymphoma treated at West China Hospital from September 2017 to September 2018. Both patient groups showed significantly higher expression of PD‐1 and PD‐L1 on CD4+ T cells, higher levels of PD‐L1 mRNA in peripheral blood mononuclear cells (PBMCs) and higher levels of soluble PD‐L1 in plasma than healthy volunteers (P < .05). In ENKTL patients, levels of PD‐L1 mRNA and soluble PD‐L1 were related to disease stage, level of lactate dehydrogenase, lymphocyte count, and copies of Epstein‐Barr genome in blood. Levels of PD‐L1 mRNA and soluble PD‐L1 were similar between healthy volunteers and ENKTL patients who showed complete remission after treatment, and uni‐ and multivariate analyses identified soluble PD‐L1 as a predictor of treatment response in ENKTL patients. Our results suggest that the levels of PD‐L1 mRNA in PBMCs and soluble PD‐L1 in plasma are useful for ENKTL staging and prediction of treatment response.

Lymph nodes may be a source for immunetherapy in gastric cancer

BACKGROUND

adoptive immunotherapy is a promising cancer therapy. Immune cells are capable of recognizing and destroying cancer cells and represent a powerful strategy, however, this approach remains technically complicated, due to the need to select and isolate immune cells from these, present cancer antigens to those cells, expanding and reinjecting them. Lymph nodes recovered during gastric cancer surgery may represent an option for immunotherapy, since they harbor an enormous amount of immune cells, which have already been presented to cancer antigens. The advantage of selecting only cancer-negative lymph has not been determined yet. The status of immune checkpoints in the immune cells within the lymph nodes was analyzed in order to try to solve this problem.

MATERIALS AND METHODS

Tissue microarrays were constructed and automated immunostaining for PD-1 and PD-L1 was performed on 143 lymph nodes from 70 patients with gastric adenocarcinoma.

RESULTS

In positive nodes, PD-L1 was only positivity in cancer cells (6%) and PD-1 was positive for B lymphocytes (60%), T lymphocytes (70%) and one case in cancer cells (2.5%). In negative nodes, most cases were positive for PD-1 in B (73.1%) and T (71.65%) lymphocytes.

CONCLUSIONS

Expression of PD-1 and PD-L1 in gastric cancer lymph nodes was demonstrated for the first time. PD-1 is expressed in positive and negative nodes, which could activate the PD-1 pathway. Lymphocytes from tumor-free lymph nodes were negative for PD-L1, and this might represent an advantage for selecting these lymph nodes as a potential source of immune cells for adoptive immunotherapy.

Low Expression of Programmed Death 1 (PD-1), PD-1 Ligand 1 (PD-L1), and Low CD8+ T Lymphocyte Infiltration Identify a Subgroup of Patients With Gastric and Esophageal Adenocarcinoma With Severe Prognosis

Prognosis of gastric and esophageal cancer is poor and treatment improvements are needed. Programmed cell death 1 receptor (PD-1) interaction with its ligand PD-L1 in tumor micro-environment promotes immune tolerance and blocking monoclonal antibodies have entered clinical practice. However, clinical significance of PD-1 and PD-L1 expression in gastric and esophageal adenocarcinomas, particularly in non-Asian patients, is still unclear. Three tissue microarrays including 190 clinically annotated esophageal (n = 31) and gastric (n = 159) adenocarcinomas and 58 paired mucosa specimens, were stained with PD-1, PD-L1, and CD8-specific reagents in indirect immunohistochemistry assays. PD-L1 expression was detectable in 23.2% of cancer specimens. High PD-1 expression was detectable in 37.3% of cases and high CD8+ infiltration in 76%. PD-L1 and high PD1 expression significantly correlated with each other (r_s = 0.404, P < 0.0001) and both significantly correlated with CD8+ infiltration (r_s = 0.435, P = 0.0003, and r_s = 0.444; P = 0.0004, respectively). CD8+ lymphocyte infiltration correlated with improved survival in univariate (P = 0.009), but not multivariate analysis. Most interestingly, multivariate analysis and Kaplan-Meier curves indicate that combined low PD-1/PD-L1 expression and low CD8+ lymphocyte infiltration significantly correlate with poor prognosis. Our data document the clinical significance of a microenvironmental signature including PD-1/PD-L1 expression and CD8+ lymphocyte infiltration in gastric and esophageal adenocarcinomas and contribute to identify a patients' subset requiring more aggressive peri-operative treatments.

Increased PD-1-positive macrophages in the tissue of gastric cancer are closely associated with poor prognosis in gastric cancer patients

Background

Programmed cell death 1 (PD-1) is one of the immune checkpoint molecules that negatively regulate the function of T cells. Although recent studies indicate that PD-1 is also expressed on other immune cells besides T cells, its role remains unclear. This study aims to evaluate PD-1 expression on macrophages and examine its effect on anti-tumor immunity in gastric cancer (GC) patients.

Methods

The frequency of PD-1⁺ macrophages obtained from GC tissue was determined by multicolor flow cytometry (n = 15). Double immunohistochemistry staining of PD-1 and CD68 was also performed to evaluate the correlations among the frequency of PD-1⁺ macrophages, clinicopathological characteristics, and prognosis in GC patients (n = 102).

Results

The frequency of PD-1⁺ macrophages was significantly higher in GC tissue than in non-tumor gastric tissue. The phagocytotic activity of PD-1⁺ macrophages was severely impaired compared with that of PD-1⁻ macrophages. The 5-year disease-specific survival rates in patients with PD-1⁺ macrophage^Low (the frequency of PD-1⁺ macrophages; < 0.85%) and those with PD-1⁺ macrophage^High (the frequency of PD-1⁺ macrophages; ≥ 0.85%) were 85.9 and 65.8%, respectively (P = 0.008). Finally, multivariate analysis showed the frequency of PD-1⁺ macrophage to be an independent prognostic factor.

Conclusions

The function of PD-1⁺ macrophage was severely impaired and increased frequency of PD-1⁺ macrophage worsened the prognosis of GC patients. PD-1–PD-L1 therapies may function through a direct effect on macrophages in GC.

The promising role of monoclonal antibodies for gastric cancer treatment

Gastric cancer (GC) is the second leading cause of cancer-related death world-wide. Despite improvements in prevention, early detection and various therapeutic options, the prognosis is still poor. GC is often diagnosed at an advanced stage with survivals less than 1 year. Chemotherapy as the mainstay of treatment in advanced stage is not of notable advantages, underlining the need for novel more effective therapeutic options. Based on current knowledge of molecular and cellular mechanisms, a number of novel biologic approaches such as monoclonal antibodies have been recently introduced for cancer treatment that mainly affect the immune system or target signaling pathways playing role in cancer and metastasis development. In this review, various monoclonal antibodies for GC therapy were explained.

Effect of Radical Surgery for Advanced Adenocarcinoma of Esophagogastric Junction on Perioperative Cellular Cell Immunity

Background: To investigate the perioperative peripheral blood levels of CD4⁺CD25⁺ regulatory T cells, programed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3) in patients with advanced Siewert type II adenocarcinoma of esophagogastric junction (AEG). Methods: Patients (n = 102) with advanced Siewert type II AEG underwent open total gastrectomy/proximal gastrectomy with a transhiatal resection of the distal esophagus and lymphadenectomy of the lower mediastinum and the abdominal D2 compartment. Flow cytometry was used to detect CD4⁺CD25⁺ T cells, PD-1 and LAG-3 expression on both CD4⁺ and CD8⁺ T cells in the peripheral blood of the Siewert type II AEG patients prior to surgery and on postoperative day (POD) 1, 3, 7, and 9. Results: The proportion of CD4⁺CD25⁺ T cells rapidly decreased on POD 1, then gradually increased and peaked at POD 7. The proportion of CD4⁺PD-1⁺ T cells significantly increased after surgery, reaching a maximum on POD 1, and remained significantly elevated on POD 3 compared to the preoperative day. The proportion of CD8⁺ PD-1⁺ and CD4⁺LAG-3⁺ T cells gradually increased after surgery and reached a peak at POD 7. The change in proportion of CD8⁺LAG-3⁺ T cells in the peripheral venous blood lymphocytes after surgery was not statistically significant. Conclusion: The change in the CD4⁺PD-1⁺ T lymphocyte ratio may likely reflect the cellular immunity status of the perioperative period.

Increased regulatory B cells are involved in immune evasion in patients with gastric cancer

Accumulating evidence has indicated that immune regulatory cells are involved in the establishment of tumoral immune evasion. However, the role of regulatory B cells (Bregs) in this remains unclear. Here, we identified a role for Bregs in immune evasion in gastric cancer (GC) patients. The frequency of peripheral Bregs was significantly higher in GC patients than in healthy controls (P = 0.0023). Moreover, the frequency of CD19⁺CD24^hiCD27⁺ B cells in GC tissue was significantly higher than in peripheral blood and healthy gastric tissue. Carboxyfluorescein succinimidyl ester labeling revealed that CD19⁺CD24^hiCD27⁺ B cells could suppress the proliferation of autologous CD4⁺ T cells. Moreover, CD19⁺CD24^hiCD27⁺ B cells inhibited the production of interferon-gamma by CD4⁺ T cells. Double staining immunohistochemistry of interleukin-10 and CD19 revealed 5-year overall survival rates of 65.4% and 13.3% in Breg^Low and Breg^High groups, respectively (P < 0.0001). Multivariate analysis indicated that the frequency of Bregs was an independent prognostic indicator in GC patients. Taken together, our results show the existence of Bregs in GC tissue, and indicate that they are significantly correlated with the prognosis of GC patients.

Expression patterns of programmed death-1 and programmed death-1 ligand-1 on T cells in gastric cancer

The aim of the present study was to evaluate programmed death-1 (PD-1) and programmed death-1 ligand-1 (PD-L1) expression in gastric carcinoma and to assess their effect on survival rate. A total of 170 surgically resected specimens were obtained from patients diagnosed with gastric carcinoma at St. Vincents Hospital, The Catholic University of Korea. Paraffin tissue sections from tissue microarray blocks were subjected to immunohistochemical analysis of PD-1 and PD-L1. In addition, PD-1 expression on CD4⁺ and CD8⁺ T cells isolated from peripheral blood mononuclear cells and gastric cancer tissues was evaluated by multicolor flow cytometry. PD-1 and PD-L1 were expressed in 30.0 and 60.5% of the gastric cancer tissues, respectively. The expression of PD-L1 was higher in patients with advanced T (P=0.035) and Tumor, Node and Metastasis stage (P=0.05). The patients with positive PD-L1 expression had shorter disease-free survival time than those without PD-L1 expression (P=0.005). Additionally, PD-L1 expression was significantly associated with poor prognosis (P=0.015). PD-1 and PD-L1 expression levels were significantly higher on CD8⁺ T cells than on CD4⁺ T cells (P<0.001). The data of the present study suggested that PD-L1 expression may be an independent indicator of poor prognosis in patients with gastric cancer. Furthermore, PD-L1 expression may play a role in immune evasion of gastric cancer.

Peripheral blood T lymphocytes are downregulated by the PD-1/PD-L1 axis in advanced gastric cancer

INTRODUCTION

Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) function as an immune checkpoint pathway that can be exploited by tumor cells to evade immuno-surveillance. The precise role of PD-1/PD-L1 inhibition of the immune response in GC is unknown. The study investigated PD-1 and PD-L1 expression on peripheral T-cells and its potential association with clinicopathological features in gastric cancer (GC) patients.

MATERIAL AND METHODS

PD-1/PD-L1 expression on CD4(+) and CD8(+) T-cells from peripheral blood of 40 patients primarily diagnosed with advanced GC was evaluated by multicolor flow cytometry.

RESULTS

The frequency of CD4(+)PD-1(+) and CD8(+)PD-1(+) cells in GC patients was higher than in the control group (p < 0.0001 and p < 0.01, respectively). Expression of PD-1 on CD8(+) cells in GC was higher than in the control group (p < 0.0001). The frequency of CD4(+)PD-L1(+) and CD8(+)PD-L1(+) cells was higher than in the control group (p < 0.0001). Expression of PD-L1 on CD4(+) and CD8(+) cells in GC was higher than in the control group (p < 0.0001). A higher frequency of CD4(+)PD-1(+) cells was found in diffuse-type compared to intestinal tumors (p < 0.029). A higher frequency of CD8(+)PD-1(+) cells was found in patients with poorly differentiated compared to well/moderately differentiated tumors (p < 0.019).

CONCLUSIONS

Downregulation of peripheral blood CD4(+) and CD8(+) lymphocytes can be associated with PD-1/PD-L1 expression. This can lead to attenuation of the general immune response in GC.

Radiation combined with macrophage depletion promotes adaptive immunity and potentiates checkpoint blockade

Emerging evidence suggests a role for radiation in eliciting anti-tumour immunity. We aimed to investigate the role of macrophages in modulating the immune response to radiation. Irradiation to murine tumours generated from colorectal (MC38) and pancreatic (KPC) cell lines induced colony-stimulating factor 1 (CSF-1). Coincident with the elevation in CSF-1, macrophages increased in tumours, peaking 5 days following irradiation. These tumour-associated macrophages (TAMs) were skewed towards an immunosuppressive phenotype. Macrophage depletion via anti-CSF (aCSF) reduced macrophage numbers, yet only achieved tumour growth delay when combined with radiation. The tumour growth delay from aCSF after radiation was abrogated by depletion of CD8 T cells. There was enhanced recognition of tumour cell antigens by T cells isolated from irradiated tumours, consistent with increased antigen priming. The addition of anti-PD-L1 (aPD-L1) resulted in improved tumour suppression and even regression in some tumours. In summary, we show that adaptive immunity induced by radiation is limited by the recruitment of highly immunosuppressive macrophages. Macrophage depletion partly reduced immunosuppression, but additional treatment with anti-PD-L1 was required to achieve tumour regression.

Surface CD200 and CD200R antigens on lymphocytes in advanced gastric cancer: a new potential target for immunotherapy

INTRODUCTION

Gastric cancer (GC) is one of the leading causes of cancer death worldwide. The membrane glycoprotein CD200, widely expressed on multiple cells/tissues, uses a structurally similar receptor (CD200R), delivering immunoregulatory signals. There is evidence that CD200/CD200R signaling suppresses anti-tumor responses in different types of malignancies. Little is known about the CD200/CD200R pathway in GC. The aim of the study was to evaluate the frequencies of CD200+ and CD200R+ lymphocytes in patients with GC.

MATERIAL AND METHODS

Forty patients primarily diagnosed with GC and 20 healthy volunteers (control group) were enrolled. The viable peripheral blood lymphocytes underwent labeling with fluorochrome-conjugated monoclonal antibodies and were analyzed using a flow cytometer.

RESULTS

In the GC group, the percentages of T CD3+, CD3+/CD4+, and CD3+/CD8+ cells expressing CD200 antigen were higher than in the control group (p < 0.00013, p < 0.0004, and p < 0.0006, respectively). In the GC group, the frequencies of T CD3+, CD3+/CD4+ and CD3+/CD8+ cells expressing CD200R were lower than in the control group (p < 0.0009, p < 0.004, and p < 0.002, respectively). The percentage of B CD19+/CD200+ lymphocytes was higher in GC patients than in the control group (p < 0.00005). Lower frequency of B CD19+/CD200R+ cells was observed in GC patients compared to the control group (p < 0.0001). No differences in the frequencies of CD200+ and CD200R+ lymphocytes were found in relation to either UICC stage or histological grading of the tumors.

CONCLUSIONS

For GC pathogenesis, deregulation of the CD200/CD200R axis is important. High percentages of lymphocytes with CD200 expression may contribute to the continuous T cell activation and development of chronic inflammation and influence gastric carcinogenesis.

Skin resident memory CD8+ T cells are phenotypically and functionally distinct from circulating populations and lack immediate cytotoxic function

The in-depth understanding of skin resident memory CD8+ T lymphocytes (TRM ) may help to uncover strategies for their manipulation during disease. We investigated isolated TRM from healthy human skin, which expressed the residence marker CD69, and compared them to circulating CD8+ T cell populations from the same donors. There were significantly increased proportions of CD8+ CD45RA- CD27- T cells in the skin that expressed low levels of killer cell lectin-like receptor G1 (KLRG1), CD57, perforin and granzyme B. The CD8+ TRM in skin were therefore phenotypically distinct from circulating CD8+ CD45RA- CD27- T cells that expressed high levels of all these molecules. Nevertheless, the activation of CD8+ TRM with T cell receptor (TCR)/CD28 or interleukin (IL)-2 or IL-15 in vitro induced the expression of granzyme B. Blocking signalling through the inhibitory receptor programmed cell death 1 (PD)-1 further boosted granzyme B expression. A unique feature of some CD8+ TRM cells was their ability to secrete high levels of tumour necrosis factor (TNF)-α and IL-2, a cytokine combination that was not seen frequently in circulating CD8+ T cells. The cutaneous CD8+ TRM are therefore diverse, and appear to be phenotypically and functionally distinct from circulating cells. Indeed, the surface receptors used to distinguish differentiation stages of blood T cells cannot be applied to T cells in the skin. Furthermore, the function of cutaneous TRM appears to be stringently controlled by environmental signals in situ.

Prognostic significance of tumor immune microenvironment and immunotherapy: Novel insights and future perspectives in gastric cancer

Despite a decrease in gastric cancer incidence, the development of novel biologic agents and combined therapeutic strategies, the prognosis of gastric cancer remains poor. Recently, the introduction of modern immunotherapy, especially using immune checkpoint inhibitors, led to an improved prognosis in many cancers. The use of immunotherapy was also associated with manageable adverse event profiles and promising results in the treatment of patients with gastric cancer, especially in heavily pretreated patients. These data have led to an accelerated approval of some checkpoint inhibitors in this setting. Understanding the complex relationship between the host immune microenvironment and tumor and the immune escape phenomenon leading to cancer occurrence and progression will subsequently lead to the identification of prognostic immune markers. Furthermore, this understanding will result in the discovery of both new mechanisms for blocking tumor immunosuppressive signals and pathways to stimulate the local immune response by targeting and modulating different subsets of immune cells. Due to the molecular heterogeneity of gastric cancers associated with different clinico-biologic parameters, immune markers expression and prognosis, novel immunotherapy algorithms should be personalized and addressed to selected subsets of gastric tumors, which have been proven to elicit the best clinical responses. Future perspectives in the treatment of gastric cancer include tailored dual immunotherapies or a combination of immunotherapy with other targeted agents with synergistic antitumor effects.

Advances in immuno-oncology biomarkers for gastroesophageal cancer: Programmed death ligand 1, microsatellite instability, and beyond

Blockade of the programmed death ligand 1 (PD-L1) and programmed cell death 1 (PD-1) receptor axis represents an effective form of cancer immunotherapy. Preclinical evidence initially suggested that gastric and gastroesophageal junction (GEJ) cancers are potentially immunotherapy-sensitive tumors. Early phase clinical trials have demonstrated promising antitumor activity with PD-1/PD-L1 blockade in advanced or metastatic gastric/GEJ cancer. Microsatellite instability (MSI) and PD-L1 expression have been shown to predict higher response to PD-1 inhibitors as highlighted by the recent approvals of pembrolizumab in treatment-refractory solid tumors with MSI status and the third-line or greater treatment of PD-L1 positive advanced gastric/GEJ cancers. However, predictive and prognostic biomarkers remain an ongoing need. In this review, we detail the preclinical evidence and early tissue biomarker analyses illustrating potential predictive biomarkers to PD-1/PD-L1 blockade in gastric/GEJ cancer. We also review the clinical development of PD-1/PD-L1 inhibitors in gastric/GEJ cancer and highlight several areas in need of future investigation in order to optimize the efficacy of PD-1/PD-L1 blockade in gastric/GEJ cancer.

Anti-PD-1 and Anti-CTLA-4 Therapies in Cancer: Mechanisms of Action, Efficacy, and Limitations

Melanoma, a skin cancer associated with high mortality rates, is highly radio- and chemotherapy resistant but can also be very immunogenic. These circumstances have led to a recent surge in research into therapies aiming to boost anti-tumor immune responses in cancer patients. Among these immunotherapies, neutralizing antibodies targeting the immune checkpoints T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) are being hailed as particularly successful. These antibodies have resulted in dramatic improvements in disease outcome and are now clinically approved in many countries. However, the majority of advanced stage melanoma patients do not respond or will relapse, and the hunt for the “magic bullet” to treat the disease continues. This review examines the mechanisms of action and the limitations of anti-PD-1/PD-L1 and anti-CTLA-4 antibodies which are the two types of checkpoint inhibitors currently available to patients and further explores the future avenues of their use in melanoma and other cancers.

PD-1 and its ligands are important immune checkpoints in cancer

Checkpoint programmed death-1 (PD-1)/programmed cell death ligands (PD-Ls) have been identified as negative immunoregulatory molecules that promote immune evasion of tumor cells. The interaction of PD-1 and PD-Ls inhibits the function of T cells and tumor-infiltrating lymphocytes (TIL) while increasing the function of immunosuppressive regulatory T cells (Tregs). This condition causes the tumor cells to evade immune response. Thus, the blockade of PD-1/PD-L1 enhances anti-tumor immunity by reducing the number and/or the suppressive activity of Tregs and by restoring the activity of effector T cells. Furthermore, some monoclonal antibodies blockading PD-1/PD-Ls axis have achieved good effect and received Food and Drug Administration approval. The role of PD-1/PD-Ls in tumors has been well studied, but little is known on the mechanism by which PD-1 blocks T-cell activation. In this study, we provide a brief overview on the discovery and regulatory mechanism of PD-1 and PD-L1 dysregulation in tumors, as well as the function and signaling pathway of PD-1 and its ligands; their roles in tumor evasion and clinical treatment were also studied.

PD-L1 expression is a prognostic factor in subgroups of gastric cancer patients stratified according to their levels of CD8 and FOXP3 immune markers

Current studies aiming at identifying single immune markers with prognostic value have limitations in the context of complex antitumor immunity and cancer immune evasion. Here, we show how the integration of several immune markers influences the predictions of prognosis of gastric cancer (GC) patients. We analyzed Tissue Microarray (TMA) by multiplex immunohistochemistry and measured the expression of immune checkpoint molecule PD-L1 together with antitumor CD8 T cells and immune suppressive FOXP3 Treg cells in a cohort of GC patients. Unsupervised hierarchical clustering analysis of these markers was used to define correlations between CD8 T, FOXP3 Treg and PD-L1 cell densities. We found that FOXP3 and PD-L1 densities were elevated while CD8 T cells were decreased in tumor tissues compared to their adjacent normal tissues. However, patient stratification based on each one of these markers individually did not show significant prognostic value on patient survival. Conversely, combination of the ratios of CD8/FOXP3 and CD8/PD-L1 enabled the identification of patient subgroups with different survival outcomes. As such, high densities of PD-L1 in patients with high CD8/FOXP3 and low CD8/PD-L1 ratios correlated with increased survival. Collectively, this work demonstrates the need for the integration of several immune markers to obtain more meaningful survival prognosis and patient stratification. In addition, our work provides insights into the complex tumor immune evasion and immune regulation by the tumor-infiltrating effector and suppressor cells, informing on the best use of immunotherapy options for treating patients.

Inhibition of IL-6-JAK/Stat3 signaling in castration-resistant prostate cancer cells enhances the NK cell-mediated cytotoxicity via alteration of PD-L1/NKG2D ligand levels

To investigate whether IL‐6 signaling affects the susceptibility of castration‐resistant prostate cancer (CRPC) cells to cytotoxic action of natural killer (NK) cells, CRPC cell lines (having different IL‐6 levels) were developed by lentiviral transduction. While observing no secreted IL‐6 level in parental C4‐2 and CWR22Rv1 cells, we found the IL‐6 expression/secretion in these cells was induced after the transduction process and the IL‐6 level difference in C4‐2siIL‐6/sc and CWR22siIL‐6/sc cell CRPC cell sets could be detected. We then found that IL‐6‐knockdown cells were more susceptible to NK cell cytotoxicity than control cells due to lowered programmed death receptor ligand 1 (PD‐L1) and increased NK group 2D (NKG2D) ligand levels. In animal studies, to concur with the in vitro results, we found that IL‐6‐expressing cell‐derived tumors were more resistant to NK cell action than the tumors of IL‐6‐knockdown cells. Further, we discovered that JAK‐Stat3 is the most critical IL‐6 downstream signaling that modulates PD‐L1/NKG2D ligand levels in CRPC cells. Furthermore, inhibition of the JAK or Stat3 signaling effectively increased the susceptibility of C4‐2sc and CWRsc cells to NK cell cytotoxicity. We observed the most effective cytotoxicity when the PD‐L1 Ab and JAK inhibitor (or Stat 3 inhibitor) were used together. These results suggest that the strategy of targeting IL‐6 signaling (or its downstream signaling) may enhance the NK cell‐mediated immune action to CRPC tumors, thus yielding clinical implications in developing future immunotherapeutics of exploiting this strategy to treat patients with CRPC.

Tumor-infiltrating CD4+ T cells in patients with gastric cancer

Background

T lymphocytes play an indispensably important role in clearing virus and tumor antigen. There is little knowledge about impacts of inhibitory molecules with cytokine on tumor-infiltrating CD4⁺ T-cells in the presence of gastric cancer (GC). This study investigated the distribution of tumor-infiltrating T-cells subset and the differentiation as well as inhibitory phenotype of T-cells from blood and tissues of GC patients.

Materials and methods

Patients with GC diagnosed on the basis of pre-operative staging and laparotomy findings were approached for enrollment between 2014 and 2015 at the Affiliated Cancer Hospital of Zhengzhou University, China. Phenotypic analysis based on isolation of tumor-infiltrating lymphocytes and intracellular IFN-γ staining assay is conducted. Statistical analysis is performed to show significance.

Results

The results showed that the percentage of CD4⁺ T-cells among CD3⁺ cells in tumors was significantly higher than that in the matched paraneoplastic tissue. CD4⁺ CD25^high CD127^low regulatory T-cells (Tregs), PD-1⁺, Tim-3⁺, and PD-1⁺ Tim-3⁺ cells were up-regulated on tumor infiltrating T-cells from patients with GC compared to their expressions on corresponding peripheral blood and peritumoral T-cells. Blockades of PD-1⁺ and Tim-3⁺ were effective in restoring tumor infiltrating T-cells’ production of interferon-gamma (IFN-γ). Combined PD-1⁺ and Tim-3⁺ inhibition had a synergistic effect on IFN-γ secretion by CD4⁺ T-cells.

Conclusion

The results suggested that the composition, inhibitors, and location of the immune infiltrate should be considered when evaluating antitumor immunotherapy. A new insight into the mechanisms underlying T cell dysfunction is provided.

Electronic supplementary material

The online version of this article (10.1186/s12935-017-0489-4) contains supplementary material, which is available to authorized users.

Understanding immune phenotypes in human gastric disease tissues by multiplexed immunohistochemistry

Background

Understanding immune phenotypes and human gastric disease in situ requires an approach that leverages multiplexed immunohistochemistry (mIHC) with multispectral imaging to facilitate precise image analyses.

Methods

We developed a novel 4-color mIHC assay based on tyramide signal amplification that allowed us to reliably interrogate immunologic checkpoints, including programmed death-ligand 1 (PD-L1), cytotoxic T cells (CD8⁺T) and regulatory T cells (Foxp3), in formalin-fixed, paraffin-embedded tissues of various human gastric diseases. By observing cell phenotypes within the disease tissue microenvironment, we were able to determine specific co-localized staining combinations and various measures of cell density.

Results

We found that PD-L1 was expressed in gastric ulcer and in tumor cells (TCs), as well as in tumor-infiltrating immune cells (TIICs), but not in normal gastric mucosa or other gastric intraepithelial neoplastic tissues. Furthermore, we found no significant reduction in CD8⁺T cells, whereas the ratio of CD8⁺T:Foxp3 cells and CD8⁺T:PD-L1 cells was suppressed in tumor tissues and elevated in adjacent normal tissues. An unsupervised hierarchical analysis also identified correlations between CD8⁺T and Foxp3⁺ tumor-infiltrating lymphocyte (TIL) densities and average PD-L1 levels. Three main groups were identified based on the results of CD8⁺T:PD-L1 ratios in gastric tumor tissues. Furthermore, integrating CD8⁺T:Foxp3 ratios, which increased the complexity for immune phenotype status, revealed 6–7 clusters that enabled the separation of gastric cancer patients at the same clinical stage into different risk-group subsets.

Conclusions

Characterizing immune phenotypes in human gastric disease tissues via multiplexed immunohistochemistry may help guide PD-L1 clinical therapy. Observing unique disease tissue microenvironments can improve our understanding of immune phenotypes and cell interactions within these microenvironments, providing the ability to predict safe responses to immunotherapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1311-8) contains supplementary material, which is available to authorized users.

Exhaustion of T lymphocytes in the tumor microenvironment: Significance and effective mechanisms

T lymphocytes play crucial roles in adaptive immune responses to tumors. However, due to different tolerance mechanisms and inhibitory effects of the tumor microenvironment (TME) on T cells, responses to tumors are insufficient. In fact, cellular and molecular suppressive mechanisms repress T cell responses in the TME, resulting in senescent, anergic and exhausted lymphocytes. Exhaustion is a poor responsive status of T cells, with up-regulated expression of inhibitory receptors, decreased production of effective cytokines, and reduced cytotoxic activity. Low immunogenicity of tumor antigens and inadequate presentation of tumor-specific antigens results in inappropriate activation of naive T lymphocytes against tumor antigens. Moreover, when effector cytotoxic T cells enter TME, they encounter a complicated network of cells and cytokines that suppress their effectiveness and turn them into exhausted T cells. Thus, the mechanism of T cell exhaustion in cancer is different from that in chronic infections. In this review we will discuss the main components such as inhibitory receptors, inflammatory cells, stromal cells, cytokine milieu as well as environmental and metabolic conditions in TME which play role in development of exhaustion. Furthermore, recent therapeutic methods available to overcome exhaustion will be discussed.

Expression and clinical significance of programmed death-1 on lymphocytes and programmed death ligand-1 on monocytes in the peripheral blood of patients with cervical cancer

The programmed death-1 (PD-1) signaling pathway serves a critical role in immune regulation and tolerance by suppressing the activation and proliferation of T cells. The aim of the present study was to investigate the effect of PD-1 and programmed death-ligand 1 (PD-L1) on the development of cervical carcinoma and cervical intraepithelial neoplasia (CIN). A total of 40 healthy controls (HC), 40 patients with CIN and 66 newly diagnosed cervical cancer patients were recruited. The expression level of PD-1 expression on peripheral cluster of differentiation (CD)4⁺ and CD8⁺ T cells and PD-L1 on monocytes was analyzed by flow cytometry. The expression level of soluble PD-L1 in serum was determined by an ELISA. The results of the present study demonstrated that the PD-1 expression level on CD4⁺ and CD8⁺ T cells was significantly increased in CIN and cervical cancer, compared with that in HC. In addition, the PD-1 expression level on CD4⁺ and CD8⁺ T cells was increased in cervical cancer, compared with that in CIN. However, the expression level of PDL-1 on CD14⁺ monocytes was increased in cancer and CIN, but limited in cancer and CIN. In addition, PD-1 expression on CD4⁺ T cells was positively associated with PD-1 expression on CD8⁺ T cells in cervical cancer (P<0.05). Further analyses revealed that the proportion of PD-1 on CD4⁺ and CD8⁺ T cells were positively associated with tumor stages. However, no difference in the degree of soluble PD-1 among cancer, CIN and HC cells was revealed. The results suggested that the PD-1 signaling pathway is involved in the development of CIN and cervical cancer.

Enhancing NK cell-mediated cytotoxicity to cisplatin-resistant lung cancer cells via MEK/Erk signaling inhibition

Major progress has been made clinically in inhibiting the programmed death receptor 1 (PD-1)/PD-L1 interaction to enhance T cell-mediated immune function, yet the effectiveness of anti-PD-L1/PD-1 agents in enhancing natural killer (NK) cell’s function remains largely unknown. Susceptibilities of cisplatin-resistant A549CisR and H157CisR cells vs. parental cells to the cytotoxic action of NK cells were examined. We found cisplatin-resistant cells more resistant to NK cell cytotoxicity than parental cells. There were constitutively higher expressions of PD-L1 in A549CisR and H157CisR cells than in parental cells in vitro, as well as in H157CisR cell-derived tumors than H157P cell-derived tumors. In contrast, we observed that the expression of PD-1 in NK cells was induced after co-culture with cisplatin-resistant cells. We also observed increased susceptibility of cisplatin-resistant cells to NK cell cytotoxicity when neutralizing antibody of PD-1 or PD-L1 was added. Further, we found that the NK group 2, member D (NKG2D) ligand levels were lower in A549CisR and H157CisR cells than in parental cells. Meanwhile, we discovered that the MEK/Erk signaling pathway played a significant role in this regulation, and the addition of a MEK/Erk pathway inhibitor significantly enhanced the PD-L1 Ab effect in enhancing NK cell cytotoxicity to cisplatin-resistant cells.

Folic acid-functionalized polyethylenimine superparamagnetic iron oxide nanoparticles as theranostic agents for magnetic resonance imaging and PD-L1 siRNA delivery for gastric cancer

Programmed death ligand-1 (PD-L1), which is highly expressed in gastric cancers, interacts with programmed death-1 (PD-1) on T cells and is involved in T-cell immune resistance. To increase the therapeutic safety and accuracy of PD-1/PD-L1 blockade, RNA interference through targeted gene delivery was performed in our study. We developed folic acid (FA)- and disulfide (SS)–polyethylene glycol (PEG)-conjugated polyethylenimine (PEI) complexed with superparamagnetic iron oxide Fe₃O₄ nanoparticles (SPIONs) as a siRNA-delivery system for PD-L1 knockdown. The characterization, binding ability, cytotoxicity, transfection efficiency, and cellular internalization of the polyplex were determined. At nitrogen:phosphate (N:P) ratios of 10 or above, the FA-PEG-SS-PEI-SPIONs bound to PD-L1 siRNA to form a polyplex with a diameter of approximately 120 nm. Cell-viability assays showed that the polyplex had minimal cytotoxicity at low N:P ratios. The FA-conjugated polyplex showed higher transfection efficiency and cellular internalization in the folate receptor-overexpressing gastric cancer cell line SGC-7901 than a non-FA-conjugated polyplex. Subsequently, we adopted the targeted FA-PEG-SS-PEI-SPION/siRNA polyplexes at an N:P ratio of 10 for function studies. Cellular magnetic resonance imaging (MRI) showed that the polyplex could also act as a T₂-weighted contrast agent for cancer MRI. Furthermore, one of four PD-L1 siRNAs exhibited effective PD-L1 knockdown in PD-L1-overexpressing SGC-7901. To determine the effects of the functionalized polyplex on T-cell function, we established a coculture model of activated T cells and SGC-7901 cells and demonstrated changes in secreted cytokines. Our findings highlight the potential of this class of multifunctional theranostic nanoparticles for effective targeted PD-L1-knockdown therapy and MRI diagnosis in gastric cancers.

Immunotherapeutic Strategies for Gastric Carcinoma: A Review of Preclinical and Clinical Recent Development

Gastric carcinoma (GC) is the 2nd most common cause of cancer-related death. Despite advances in conventional treatment and surgical interventions, a high percentage of GC patients still have poor survival. Recently, immunotherapy has become a promising approach to treat GC. Here, we present preclinical and clinical studies encouraging the use of vaccination, adoptive T-cell therapy (ACT), and immune checkpoint inhibitors, such as programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). The ongoing immunotherapy clinical trials have shown promising results in safety and tolerability even in late-stage GC patients. Moreover, we highlight that the combination of ACT with chemotherapy could be the best choice to treat GC.

Increased expression of programmed cell death protein 1 on NK cells inhibits NK-cell-mediated anti-tumor function and indicates poor prognosis in digestive cancers

Abnormal expression of activating/inhibitory receptors leads to natural killer (NK) cells dysfunction in tumor. Here we show that programmed cell death protein 1 (PD-1), a well-known immune checkpoint of T cells, is highly expressed on peripheral and tumor-infiltrating NK cells from patients with digestive cancers including esophageal, liver, colorectal, gastric and biliary cancer. The increased PD-1 expression on NK cells indicates poorer survival in esophageal and liver cancers. Blocking PD-1/PD-L1 signaling markedly enhances cytokines production and degranulation and suppresses apoptosis of NK cells in vitro. PD-1/PD-L1 exerts inhibitory effect through repressing the activation of PI3K/AKT signaling in NK cells. More importantly, a PD-1 blocking antibody was found to significantly suppress the growth of xenografts in nude mice, and this inhibition of tumor growth was completely abrogated by NK depletion. These findings strongly suggested that PD-1 is an inhibitory regulator of NK cells in digestive cancers. PD-1 blockade might be an efficient strategy in NK cell-based tumor immunotherapy.

Beyond melanoma: inhibiting the PD-1/PD-L1 pathway in solid tumors

Immune checkpoint inhibitors have been identified as breakthrough treatment in melanoma given its dramatic response to PD-1/PD-L1 blockade. This is likely to extend to many other cancers as hundreds of clinical trials are being conducted or proposed using this exciting modality of therapy in a variety of malignancies. While immune checkpoint inhibitors have been extensively studied in melanoma and more recently in lung cancer, little is known regarding immune checkpoint blockade in other cancers. This review will focus on the tumor immune microenvironment, the expression of PD-1/PD-L1 and the effect of immune modulation using PD-1 or PD-L1 inhibitors in patients with head and neck, prostate, urothelial, renal, breast, gastrointestinal and lung cancers.

Role of modern immunotherapy in gastrointestinal malignancies: a review of current clinical progress

Gastrointestinal (GI) cancers are a group of highly aggressive malignancies with a huge disease burden worldwide. There is clearly a significant unmet need for new drugs and therapies to further improve the treatment outcomes of GI malignancies. Immunotherapy is a novel treatment strategy that is emerging as an effective and promising treatment option against several types of cancers. CTLA-4 and PD-1 are critical immune checkpoint molecules that negatively regulate T cell activation via distinct mechanisms. Immune checkpoint blockade with antibodies directed against these pathways has already shown clinical efficacy that has led to their FDA approval in the treatment of several solid tumors including melanoma, non-small cell lung cancer, renal cell carcinoma, urothelial carcinoma, and head and neck cancer. This review will summarize the current clinical progress of modern immunotherapy in the field of GI tumors, with a special focus on immune checkpoint blockade.

Expression of Programmed Cell Death Protein 1 by Tumor-Infiltrating Lymphocytes and Tumor Cells is Associated with Advanced Tumor Stage in Patients with Esophageal Adenocarcinoma

Background

Despite recent advances in the therapy for adenocarcinoma of the esophagogastric junction (AEG), overall prognosis remains poor. Programmed cell death protein 1 (PD1) is a co-inhibitory receptor primarily expressed by T-cells. Tumor cells can escape anticancer immune responses by triggering the PD1 pathway. Moreover, PD1 receptor engagement on cancer cells may trigger tumor-intrinsic growth signals. This study aimed to evaluate the potential clinical relevance of PD1 expression by tumor-infiltrating lymphocytes (TILs) and cancer cells in the AEG.

Methods

Patients with AEG who underwent esophagectomy from 1992 to 2011 were included in the study. Expression of PD1was evaluated by immunohistochemistry and correlated with long-term overall survival (OS), disease-free survival (DFS), and various clinicopathologic parameters.

Results

Tumor biospecimens from 168 patients were analyzed. In the analysis, 81% of the patients showed high tumoral frequencies (>5%) of PD1-expressing TILs (TIL-PD1⁺), and 77% of patient tumors harbored high levels (>5%) of PD1⁺ cancer cells (cancer-PD1⁺). Expression of PD1 by TILs and cancer cells correlated significantly (p < 0.05) with patients’ tumor stage and lymph node involvement. Compared with the patients who had low tumoral frequencies of PD1⁺ TILs or cancer cells, the TIL-PD1⁺ and cancer-PD1⁺ patients demonstrated significantly reduced DFS in the univariate analysis (5-year DFS: 73.3 vs. 41.9%, log-rank 0.008 and 71.3 vs. 41.6%, p = 0.008, respectively). Additionally, the cancer-PD1⁺ patients showed significantly decreased OS in the univariate analysis compared with the cancer-PD1⁻ patients (5-year OS: 68.8 vs. 43.5%; p = 0.047). However, these correlations did not reach significance in the multivariate analysis.

Conclusions

The PD1 receptor is expressed by both TILs and cancer cells in AEG. High expression of PD1 is associated with advanced tumor stage and lymph node involvement, but not with survival.

Immune checkpoint inhibition and its relationship with hypermutation phenoytype as a potential treatment for Glioblastoma

Glioblastoma (GBM) is the most common malignant brain tumour in adults. Current prognosis with standard treatment is poor. Immunotherapy is a new paradigm in tumour management. Specifically, recent advances in the field of immune checkpoint molecules have led to dramatic results in many cancers. Inhibition of one particular, programmed cell death-1 (PD-1) has recently been shown to be highly effective in melanoma and non-small cell lung cancer. There has also been recent data to suggest potential benefit in GBM. There also appears to be a relationship between immune checkpoint inhibition and hypermutation, in particular with the mismatch repair process. In this review we look at the current knowledge of immune checkpoint inhibitors with a focus on the PD-1 pathway. We will also review the evidence of PD-1 inhibition in GBM and the role of hypermutation in PD-1 inhibition.

Tumor antigen-specific CD8+ T cells are negatively regulated by PD-1 and Tim-3 in human gastric cancer

Cytotoxic CD8 T lymphocytes that are present in tumors and capable of recognizing tumor epitopes are nevertheless generally important in eliciting tumor rejection. NY-ESO-1 is a major target of CD8⁺ T cell recognition in gastric cancer (GC) and is among the most immunogenic tumor antigens defined to date. Thus, identifying the immune escape mechanisms responsible for inducing tumor-specific CD8⁺ T cell dysfunction may reveal effective strategies for immunotherapy. In an effort to understand in vivo tolerance mechanisms, we assessed the phenotype and function of NY-ESO-1-specific CD8⁺ T cells derived from peripheral blood lymphocytes (PBLs) and tumor-associated lymphocytes (TALs) of GC patients. Here, we report that Tim-3 expression defines a subpopulation of PD-1⁺ exhausted NY-ESO-1-specific CD8⁺ T cell and PD-1⁺Tim-3⁺ CD8⁺ T cells represented the largest subset of NY-ESO-1-specific CD8⁺ T cells in GC patients. Functionally, CD8⁺PD-1⁺Tim-3⁺ T cells were more impaired in IFN-γ, TNF-α and IL-2 production compared with PD-1⁺Tim-3^- or PD-1^-Tim-3^- subsets. Dual blockade of Tim-3 and PD-1 during T-cell priming efficiently augmented proliferation and cytokine production by NY-ESO-1-specific CD8⁺ T cells could potentially be improved by therapeutic targeting of these inhibitory receptors, indicating that antitumor function of NY-ESO-1-specific CD8⁺ T cells could potentially be improved by therapeutic targeting of these inhibitory receptors.

CRISPR-Cas9-mediated disruption of PD-1 on human T cells for adoptive cellular therapies of EBV positive gastric cancer

The successful use of immune cell checkpoint inhibitors PD-1 and PD-L1, over the past 5 y has raised the concern of using immunotherapy to treat various cancers. Epstein-Barr virus-associated gastric cancer (EBVaGC) exhibits high infiltration of lymphocytes and high amplification of immune-related genes including PD-L1 as distinguished from Epstein-Barr virus-non-associated gastric cancer (EBVnGC). Here, we presume that this PD-1/PD-L1 pathway may hinder the efficacy of adoptive T cell therapy toward EBVaGC. These studies reveal possibility of generating PD-1-disrupted CTL by CRISPR-Cas9 system and demonstrate enhanced immune response of these PD-1-disrupted CTLs to the EBV-LMP2A antigen and superior cytotoxicity to the EBV-positive gastric cancer cell. In addition, when combined with low-dose radiotherapy, these PD-1-disrupted CTLs mediated an impressive antitumor effect in a xenograft mouse model of EBVaGC. Taken together, these studies illustrate PD-1/PD-L1-mediated immune tolerance of EBVaGC and provide a new strategy for targeting immune checkpoints to break the tolerance for the T cell-based adoptive therapy.