Immunotherapy in gastric cancer

Report from the 17th Annual Western Canadian Gastrointestinal Cancer Consensus Conference; Edmonton, Alberta; 11-12 September 2015

The 17th annual Western Canadian Gastrointestinal Cancer Consensus Conference (wcgccc) was held in Edmonton, Alberta, 11-12 September 2015. The wcgccc is an interactive multidisciplinary conference attended by health care professionals from across Western Canada (British Columbia, Alberta, Saskatchewan, and Manitoba) who are involved in the care of patients with gastrointestinal cancer. Surgical, medical, and radiation oncologists; pathologists; radiologists; and allied health care professionals participated in presentation and discussion sessions for the purposes of developing the recommendations presented here. This consensus statement addresses current issues in the management of gastric cancer.

Immunological battlefield in gastric cancer and role of immunotherapies

Like the wars predating the First World War where human foot soldiers were deemed tools in the battlefield against an enemy, so too are the host immune cells of a patient battling a malignant gastric cancer. Indeed, the tumour microenvironment resembles a battlefield, where the patient’s immune cells are the defence against invading tumour cells. However, the relationship between different immune components of the host response to cancer is more complex than an “us against them” model. Components of the immune system inadvertently work against the interests of the host and become pro-tumourigenic while other components soldier on against the common enemy – the tumour cell.

Efficacy of adoptive cellular therapy in patients with gastric cancer: a meta-analysis

Aim: To systemically evaluate the efficacy and safety of adoptive cellular therapy for the treatment of gastric cancer (GC). Materials & methods: We performed a systemic review and meta-analysis of nine eligible trials with GC and evaluated the effect of adoptive cellular therapy on the overall survival (OS) rate, T-cell subsets and adverse events. Results: Overall, 829 patients were involved in the analysis. Adoptive cellular therapy significantly improved the OS rate compared with the control group. Meanwhile, we observed greatly increased percentages of CD3+, CD4+ and CD4+/CD8+ in cellular therapy groups. Conclusion: Adoptive cellular therapy combined with adjuvant therapy resulted in significantly better OS rates, progression-free survival and T-lymphocyte responses in patients with GC.

Changing strategies for target therapy in gastric cancer

In spite of a worldwide decrease in the incidence of gastric cancer, this malignancy still remains one of the leading causes of cancer mortality. Great efforts have been made to improve treatment outcomes in patients with metastatic gastric cancer, and the introduction of trastuzumab has greatly improved the overall survival. The trastuzumab treatment took its first step in opening the era of molecular targeted therapy, however several issues still need to be resolved to increase the efficacy of targeted therapy. Firstly, many patients with metastatic gastric cancer who receive trastuzumab in combination with chemotherapeutic agents develop resistance to the targeted therapy. Secondly, many clinical trials testing novel molecular targeted agents with demonstrated efficacy in other malignancies have failed to show benefit in patients with metastatic gastric cancer, suggesting the importance of the selection of appropriate indications according to molecular characteristics in application of targeted agents. Herein, we review the molecular targeted agents currently approved and in use, and clinical trials in patients with metastatic gastric cancer, and demonstrate the limitations and future direction in treatment of advanced gastric cancer.

The prediction of survival of patients with gastric cancer with PD-L1 expression using contrast-enhanced ultrasonography

Gastric cancer is the one of the most common cancers around the world. The prognosis of gastric cancer remains poor, due to the biological characteristics of the primary tumor as well as the recurrence after treatment. Accumulating evidence suggests the implication of programmed death ligand-1 (PD-L1) in the pathogenesis and prognosis of cancer. This study aimed to explore the CEUS as a valuable tool to improve the assessment of the therapeutic effect of the PD-L1 blocker in the treatment of gastric cancer. A total number of 105 patients with gastric cancer were enrolled in this study from June 2008 to December 2011 in our hospital. The association of PD-L1 expression level (105 cases) and CEUS parameters (100 cases) with the prognosis of gastric cancer was examined. The results showed that PD-L1-positive staining was associated with the depth of invasion, differentiation, and poor prognosis of patients with gastric cancer. The CEUS intensity (positive) exhibited poor prognosis compared to the negative counterpart. Moreover, PD-L1 and CEUS co-positivity was significantly related to a poor prognosis. The characteristic of ultrasonography images correlated with the expression of PD-L1 (r = 0.46, P = 0.0003). Collectively, the mean intensity of contrast-enhanced ultrasonography is a useful predictor in the PD-L1 expression in gastric cancer. The ultrasonography and CEUS parameter could be considered as the predictor of response to PD-L1 blocker treatment in the clinical practice.

Strategies and Advancements in Harnessing the Immune System for Gastric Cancer Immunotherapy

In cancer biology, cells and molecules that form the fundamental components of the tumor microenvironment play a major role in tumor initiation, and progression as well as responses to therapy. Therapeutic approaches that would enable and harness the immune system to target tumor cells mark the future of anticancer therapy as it could induce an immunological memory specific to the tumor type and further enhance tumor regression and relapse-free survival in cancer patients. Gastric cancer is one of the leading causes of cancer-related mortalities that has a modest survival benefit from existing treatment options. The advent of immunotherapy presents us with new approaches in gastric cancer treatment where adaptive cell therapies, cancer vaccines, and antibody therapies have all been used with promising outcomes. In this paper, we review the current advances and prospects in the gastric cancer immunotherapy. Special focus is laid on new strategies and clinical trials that attempt to enhance the efficacy of various immunotherapeutic modalities in gastric cancer.

Radiolabeling and evaluation of (64)Cu-DOTA-F56 peptide targeting vascular endothelial growth factor receptor 1 in the molecular imaging of gastric cancer

Noninvasive imaging of vascular endothelial growth factor receptor 1 (VEGFR1) remains a great challenge in early diagnosis of gastric cancer. Here we reported the synthesis, radiolabeling, and evaluation of a novel (64)Cu-radiolabeled peptide for noninvasive positron emission tomography (PET) imaging of VEGFR1 positive gastric cancer. The binding of modified peptide WHSDMEWWYLLG (termed as F56) to VEGER-1 expressed in gastric cancer cell BCG823 has been confirmed by immune-fluorescence overlap. DOTA-F56 was designed and prepared by solid-phase synthesis and folded in vitro. (64)Cu-DOTA-F56 was synthesized in high radiochemical yield and high specific activity (S.A. up to 255.6 GBq/mmol). It has excellent in vitro stability. Micro-PET imaging of (64)Cu-DOTA-F56 identifies tumor in BCG823 tumor-bearing mice, while that of (18)F-FDG does not. Immunohistochemical analysis of excised BCG823 xenograft showed colocalization between the PET images and the staining of VEGFR1. These results demonstrated that (64)Cu-DOTA-F56 peptide has potential as a noninvasive imaging agent in VEGFR1 positive tumors.

Kyoto global consensus report on Helicobacter pylori gastritis

OBJECTIVE

To present results of the Kyoto Global Consensus Meeting, which was convened to develop global consensus on (1) classification of chronic gastritis and duodenitis, (2) clinical distinction of dyspepsia caused by Helicobacter pylori from functional dyspepsia, (3) appropriate diagnostic assessment of gastritis and (4) when, whom and how to treat H. pylori gastritis.

DESIGN

Twenty-three clinical questions addressing the above-mentioned four domains were drafted for which expert panels were asked to formulate relevant statements. A Delphi method using an anonymous electronic system was adopted to develop the consensus, the level of which was predefined as ≥80%. Final modifications of clinical questions and consensus were achieved at the face-to-face meeting in Kyoto.

RESULTS

All 24 statements for 22 clinical questions after extensive modifications and omission of one clinical question were achieved with a consensus level of >80%. To better organise classification of gastritis and duodenitis based on aetiology, a new classification of gastritis and duodenitis is recommended for the 11th international classification. A new category of H. pylori-associated dyspepsia together with a diagnostic algorithm was proposed. The adoption of grading systems for gastric cancer risk stratification, and modern image-enhancing endoscopy for the diagnosis of gastritis, were recommended. Treatment to eradicate H. pylori infection before preneoplastic changes develop, if feasible, was recommended to minimise the risk of more serious complications of the infection.

CONCLUSIONS

A global consensus for gastritis was developed for the first time, which will be the basis for an international classification system and for further research on the subject.

Conjugation of toll-like receptor-7 agonist to gastric cancer antigen MG7-Ag exerts antitumor effects

AIM: To investigate the effects of our tumor vaccines on reversing immune tolerance and generating therapeutic response.

METHODS: Vaccines were synthesized by solid phase using an Fmoc strategy, where a small molecule toll-like receptor-7 agonist (T7) was conjugated to a monoclonal gastric cancer 7 antigen mono-epitope (T7-MG1) or tri-epitope (T7-MG3). Cytokines were measured in both mouse bone marrow dendritic cells and mouse spleen lymphocytes after exposed to the vaccines. BALB/c mice were intraperitoneally immunized with the vaccines every 2 wk for a total of three times, and then subcutaneously challenged with Ehrlich ascites carcinoma (EAC) cells. Three weeks later, the mice were killed, and the tumors were surgically removed and weighed. Serum samples were collected from the mice, and antibody titers were determined by ELISA using an alkaline phosphate-conjugated detection antibody for total IgG. Antibody-dependent cell-mediated cytotoxicity was detected by the lactate dehydrogenase method using natural killer cells as effectors and antibody-labeled EAC cells as targets. Cytotoxic T lymphocyte activities were also detected by the lactate dehydrogenase method using lymphocytes as effectors and EAC cells as targets.

RESULTS: Vaccines were successfully synthesized and validated by analytical high performance liquid chromatography and electrospray mass spectrometry, including T7, T7-MG1, and T7-MG3. Rapid inductions of tumor necrosis factor-α and interleukin-12 in bone marrow dendritic cells and interferon γ and interleukin-12 in lymphocytes occurred in vitro after T7, T7-MG1, and T7-MG3 treatment. Immunization with T7-MG3 reduced the EAC tumor burden in BALB/c mice to 62.64% ± 5.55% compared with PBS control (P < 0.01). Six or nine weeks after the first immunization, the monoclonal gastric cancer 7 antigen antibody increased significantly in the T7-MG3 group compared with the PBS control (P < 0.01). As for antibody-dependent cell-mediated cytotoxicity, antisera obtained by immunization with T7-MG3 were able to markedly enhance cell lysis compared to PBS control (31.58% ± 2.94% vs 18.02% ± 2.26%; P < 0.01). As for cytotoxic T lymphocytes, T7-MG3 exhibited obviously greater cytotoxicity compared with PBS control (40.92% ± 4.38% vs 16.29% ± 1.90%; P < 0.01).

CONCLUSION: A successful method is confirmed for the design of gastric cancer vaccines by chemical conjugation of T7 and multi-repeat-epitope of monoclonal gastric cancer 7 antigen.

Immunotherapy of Ovarian Cancer: The Role of Checkpoint Inhibitors

Ovarian cancer is the most important cause of gynecological cancer-related mortality, with the majority of women presenting with advanced disease. Although surgery and chemotherapy can improve survival rates, it is necessary to integrate alternative strategies to improve the outcomes. Advances in understanding the role of immune system in the pathogenesis of cancer have led to the rapid evolvement of immunotherapy, which might establish a sustained immune system response against recurring cancer cells. Recently, it has emerged that powerful immunologic effector cells may be blocked by inhibitory regulatory pathways controlled by specific molecules often called “immune checkpoints,” which turn off the immune system. Similarly, cancer cells are able to use these checkpoints to avoid immune control and rejection. Inhibition of these inhibitory pathways represents a potent strategy in the fight against cancer and is currently under investigation with encouraging results in some cancers, such as melanoma. In ovarian cancer researches are still in an early phase, but with promising results. In this review we will explore the rationale of immunotherapy in ovarian cancer with a special focus on these emerging molecules.

Current and Future Therapies for Advanced Gastric Cancer

The treatment of patients with advanced gastric cancer remains a challenging area of oncology. Extensive trials of differing chemotherapy regimens have yielded no international consensus on the optimal combination, and overall survival with chemotherapy alone remains poor. Recently an improved understanding of the molecular drivers of the disease has opened up promising new avenues of treatment through the use of biological targeted agents. The anti-HER2 monoclonal antibody trastuzumab was the first targeted agent to significantly prolong survival in the first-line treatment of a molecularly-selected subgroup of patients. More recently the anti-vascular endothelial growth factor receptor 2 monoclonal antibody ramucirumab has demonstrated a modest survival benefit in previously treated patients as both a monotherapy and in combination with chemotherapy. Immunotherapy and the use of checkpoint inhibitors are a further exciting area of development with promising preliminary results for the activity of the anti-Programmed Death 1 Receptor antibody pembrolizumab and ongoing trials of a number of immune-modulating agents. Continuing research to identify novel targets and therapies aims to make further incremental gains in survival. In this review we outline the evidence base supporting current chemotherapy regimens and describe the latest advances in the development and use of molecularly targeted and immune-modulating agents.

Gastric cancer and the epoch of immunotherapy approaches

The incidence of gastric cancer (GC) fell dramatically over the last 50 years, but according to IARC-Globocan 2008, it is the third most frequent cause of cancer-related deaths with a case fatality GC ratio higher than other common malignancies. Surgical resection is the primary curative treatment for GC though the overall 5-year survival rate remains poor (approximately 20%-25%). To improve the outcome of resectable gastric cancer, different treatment strategies have been evaluated such as adjuvant or perioperative chemotherapy. In resected gastric cancer, the addition of radiotherapy to chemotherapy does not appear to provide any additional benefit. Moreover, in metastatic patients, chemotherapy is the mainstay of palliative therapy with a median overall survival of 8-10 mo and objective response rates of merely 20%-40%. Therefore, the potential for making key beneficial progress is to investigate the GC molecular biology to realize innovative therapeutic strategies, such as specific immunotherapy. In this review, we provide a panoramic view of the different immune-based strategies used for gastric cancer treatment and the results obtained in the most significant clinical trials. In detail, firstly we describe the therapeutic approaches that utilize the monoclonal antibodies while in the second part we analyze the cell-based immunotherapies.

Helicobacter pylori update: gastric cancer, reliable therapy, and possible benefits

Helicobacter pylori infection contributes to the development of diverse gastric and extragastric diseases. The infection is necessary but not sufficient for the development of gastric adenocarcinoma. Its eradication would eliminate a major worldwide cause of cancer death, therefore there is much interest in identifying how, if, and when this can be accomplished. There are several mechanisms by which H pylori contributes to the development of gastric cancer. Gastric adenocarcinoma is one of many cancers associated with inflammation, which is induced by H pylori infection, yet the bacteria also cause genetic and epigenetic changes that lead to genetic instability in gastric epithelial cells. H pylori eradication reduces both. However, many factors must be considered in determining whether treating this bacterial infection will prevent cancer or only reduce its risk-these must be considered in designing reliable and effective eradication therapies. Furthermore, H pylori infection has been proposed to provide some benefits, such as reducing the risks of obesity or childhood asthma. When tested, these hypotheses have not been confirmed and are therefore most likely false.

Immunotherapy in Melanoma, Gastrointestinal (GI), and Pulmonary Malignancies

Oncologic immunotherapy involves stimulating the immune system to more effectively identify and eradicate tumor cells that have successfully adapted to survive the body's natural immune defenses. Immunotherapy has shown great promise thus far by prolonging the lives of patients with a variety of malignancies, and has added a crucial new set of tools to the oncologists' armamentarium. The aim of this paper is to provide an overview of immunotherapy treatment options that are currently available and under active research for melanoma, gastrointestinal (esophageal, gastric, pancreatic, and colorectal), and pulmonary malignancies. Potential biomarkers that may predict favorable responses to immunotherapies are discussed where applicable, as are future avenues of research in this rapidly evolving field.

Upregulation of PD-L1 and APE1 is associated with tumorigenesis and poor prognosis of gastric cancer

INTRODUCTION

Gastric cancer is a fatal malignancy with a rising incidence rate. Effective methods for early diagnosis, monitoring metastasis, and prognosis are currently unavailable for gastric cancer. In this study, we examined the association of programmed death ligand-1 (PD-L1) and apurinic/apyrimidinic endonuclease 1 (APE1) expression with the prognosis of gastric cancer.

METHODS

The expressions of PD-L1 and APE1 were detected by immunohistochemistry in 107 cases of human gastric carcinoma. The correlation of PD-L1 and APE1 expression with the clinicopathologic features of gastric carcinoma was analyzed by SPSS version 19.0.

RESULTS

The positive expression rates of PD-L1 and APE1 in gastric cancer tissues were 50.5% (54/107) and 86.9% (93/107), respectively. PD-L1 and APE1 positive expressions were significantly associated with depth of invasion, lymph node metastasis, pathological type, overall survival, and higher T stage. Furthermore, the expression of PD-L1 in highly differentiated gastric cancers was higher than that in poorly differentiated cancers (P=0.008). Moreover, the expression of APE1 and PD-L1 in gastric cancers was positively correlated (r=0.336, P<0.01). Multivariate analysis showed that the depth of invasion was a significant prognostic factor (risk ratio 19.91; P=0.000), but there was no significant relationship with PD-L1, APE1, prognosis, and other characteristics.

CONCLUSION

The deregulation of PD-L1 and APE1 might contribute to the development and the poor prognosis of gastric cancer. Our findings suggest that high expression of PD-L1 and APE1 is a risk factor of gastric cancer and a new biomarker to predict the prognosis of gastric cancer. Furthermore, our findings suggest that targeting the PD-L1 and APE1 signaling pathways may be a new strategy for cancer immune therapy and targeted therapy for gastric cancer, especially in patients with deep invasion and lymph node metastasis.

Changing the natural history of metachronous gastric cancer after H. pylori eradication

Metachronous gastric cancer occurs frequently following endoscopic removal of an early gastric cancer. H. pylori eradication significantly reduces that risk. While, the pathogenesis of this phenomenon remains unclear, it is clear that the natural history of metachronous gastric cancer is altered following H. pylori eradication. Genetic instability of host cells induced by inflammation, H. pylori, host or environmental factors can result in the production of malignant cells. H. pylori eradication reduces and alters the inflammation, and can reverse epigenetic damage and abnormal expression of miRNA's. Fundamentally, H. pylori eradication stops the progression and may reverse some of the damage to the mucosa resulting in improved acid secretion and improving the gastric microbiome. Because the risk of developing metachronous cancer varies among patients, prospective research is needed to identify reliable biomarkers to predict development of metachronous cancer as well as to define surveillance methods, intervals, and duration. Some candidate examples of prognostic or predictive biomarkers for the prediction of subsequent risk include the presence or absence, titers, and changes in anti-H. pylori IgG and or anti-CagA antibodies, serum pepsinogens, gastrin, and miRNAs.

Harnessing immunosurveillance: current developments and future directions in cancer immunotherapy

Despite improved methods of cancer detection and disease management over the last few decades, cancer remains a major public health problem in many societies. Conventional therapies, such as chemotherapy, radiation, and surgery, are not usually sufficient to prevent disease recurrence. Therefore, efforts have been focused on developing novel therapies to manage metastatic disease and to prolong disease-free and overall survival, by modulating the immune system to alleviate immunosuppression, and to enhance antitumor immunity. This review discusses protumor mechanisms in patients that circumvent host immunosurveillance, and addresses current immunotherapy modalities designed to target these mechanisms. Given the complexity of cancer immunosuppressive mechanisms, we propose that identification of novel disease biomarkers will drive the development of more targeted immunotherapy. Finally, administration of different classes of immunotherapy in combination regimens, will be the ultimate route to impact low survival rates in advanced cancer patients.

Prognostic value of preoperative absolute lymphocyte count in recurrent hepatocellular carcinoma following thermal ablation: a retrospective analysis

Purpose

To investigate the prognostic value of preoperative absolute lymphocyte count (ALC) in recurrent hepatocellular carcinoma (RHCC) following thermal ablation.

Materials and methods

We retrospectively analyzed the relationship between preoperative ALC and the clinicopathologic factors and long-term prognosis in 423 RHCC patients who underwent curative thermal ablation. Correlation analysis, receiver operating characteristic (ROC) calculation, Kaplan–Meier curves, and multivariate regression were used for statistical analysis.

Results

The median time to recurrence was 12 months for RHCC patients after thermal ablation. On multivariate Cox regression analysis, preoperative ALC was an independent risk factor for cancer recurrence, along with tumor differentiation and α-fetoprotein level. ALC ≥1.64×10⁹/L defined by ROC calculation was associated with prolonged survival (area under the curve 0.741, P<0.001). Patients with ALC ≥1.64×10⁹/L showed a mean survival of 20.2 months versus 11.6 months for patients with ALC <1.64×10⁹/L (P<0.001). Patients were stratified into high and low groups according to ALC status. After excluding the basic parameters between groups, the 1- and 3-year recurrence rates in the high group were 20.9% and 29.5%, respectively, which were significantly lower than those of the low group (58.4% and 71.9%, respectively; P<0.001). The recurrence-free survival rates in the two groups analyzed by Kaplan–Meier curves were significantly different (P<0.001).

Conclusion

Preoperative ALC is a powerful prognostic factor for RHCC recurrence after thermal ablation, which suggests that maintaining a high ALC in RHCC patients might improve cancer outcomes.

Expression and clinical significance of Centrosomal protein 55 (CEP55) in human urinary bladder transitional cell carcinoma

Bladder cancer (BC) is one among the most common and lethal urothelial malignancies worldwide. The expression of cancer-testis (CT) antigens in some tumours and restricted expression among normal tissues make CT antigens as attractive vaccine targets. In this context, we evaluated Centrosomal protein 55 kDa (CEP55), which is specifically expressed in normal human testis and various malignancies. Until the expression pattern of CEP55 in transitional cell carcinoma (TCC) of human urinary bladder and its clinical significance are not known. The aim of the present study is to evaluate mRNA/protein expression of CEP55 in TCCs of urinary bladder and correlate its expression with the clinicopathological characteristics of BC patients. In this study, the methods of quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were used to investigate mRNA/protein expression of CEP55 in TCC. Independent Student's t test, ANOVA and Chi-square (χ(2)) were used to analyze the data statistically. We observed CEP55 mRNA overexpression in testis and 48.7% of BC patients. Relative mean fold expression of CEP55 mRNA was found to be significantly (p<0.01) higher in muscle-invasive bladder cancer (MIBC) as compared to non-muscle-invasive bladder cancer (NMIBC) patients (7.88±3.88 vs. 4.75±2.30, p=0.01). CEP55 protein expression was evaluated using IHC and cytoplasmic staining pattern was recorded in formalin fixed, paraffin-embedded (FFPE) bladder tumour tissues. No significant difference was observed in protein expression of CEP55 between the two groups (NMIBC and MIBC patients) (72.2% vs. 69.0%, p=0.774). No significant protein expression of CEP55 was observed among adjacent noncancerous tissues (ANCTs) and benign prostatic hyperplasia (BPH) used as control. Our study results suggest that CEP55 mRNA/protein expression was observed is specific to TCC of human urinary bladder and might be used as a diagnostic biomarker and vaccine target in development of BC specific immunotherapy.