Pembrolizumab for the treatment of gastric cancer

Feature Engineering-Assisted Drug Repurposing on Disease-Drug Transcriptome Profiles in Gastric Cancer

Gastric cancer is one of the most common and deadly types of cancer in the world. To develop new biomarkers and drugs to diagnose and treat this cancer, it is necessary to identify the differences between the transcriptome profiles of gastric cancer and healthy individuals, identify critical genes associated with these differences, and make potential drug predictions based on these genes. In this study, using two gene expression datasets related to gastric cancer (GSE19826 and GSE79973), 200 genes that were ready for machine learning were selected, and their expression levels were analyzed. The best 100 genes for the model were chosen with the permutation feature importance method, and central genes, such as SCARB1, ETV3, SPATA17, FAM167A-AS1, and MTBP, which were shown to be associated with gastric cancer, were identified. Then, using the drug repurposing method with the Connectivity Map CLUE Query tools, potential drugs such as Forskolin, Gestrinone, Cediranib, Apicidine, and Everolimus, which showed a highly negative correlation with the expression levels of the selected genes, were identified. This study provides a method to develop new approaches to diagnosing and treating gastric cancer by comparing the transcriptome profiles of patients gastric cancer and performing a feature engineering-assisted drug repurposing analysis based on cancer data.

Geriatric nutritional risk index predicts the prognosis of gastric cancer patients treated with immune checkpoint inhibitors

The nutritional status is closely linked to the immune function of patients. Previous studies have demonstrated the utility of the Geriatric Nutritional Risk Index (GNRI) in assessing nutritional status. The aim of this study is to investigate the prognostic significance of GNRI in patients with gastric cancer who received immune checkpoint inhibitor (ICI) therapy. The study enrolled 89 gastric cancer patients who received different types of immune checkpoint inhibitors (ICIs) between August 2016 and December 2020, along with 57 patients who underwent chemotherapy during the same period as a control group. The GNRI cutoff point was established based on prior research. Differences in clinical and pathological features were analyzed using the Chi-square test or independent samples t-test. Univariate and multivariate analyses were used to identify prognostic factors for both progression-free survival (PFS) and overall survival (OS). Furthermore, nomograms were created to predict the likelihood of patient survival. There were 31 cases (21.2%) with GNRI < 92.00 and 115 cases (78.8%) with GNRI ≥ 92.00. Patients with low GNRI had significantly shorter PFS (21.33 months vs 28.37 months, P = .001) and OS (33.06 months vs 41.63 months, P = .001) than those with high GNRI, among all patients. Similar results were also found in patients treated with ICIs. Additionally, GNRI was identified as an independent prognostic factor. The C-index and 95% CI of the nomograms for predicting survival probabilities were 0.667 (0.600-0.735) and 0.685 (0.622-0.749), respectively. GNRI was significantly associated with survival time in patients with gastric cancer who received ICIs, patients with low GNRI had shorter PFS and OS. GNRI might be able to identify patients who might benefit from ICIs.

The viral etiology of EBV-associated gastric cancers contributes to their unique pathology, clinical outcomes, treatment responses and immune landscape

Epstein-Barr virus (EBV) is a pathogen known to cause a number of malignancies, often taking years for them to develop after primary infection. EBV-associated gastric cancer (EBVaGC) is one such malignancy, and is an immunologically, molecularly and pathologically distinct entity from EBV-negative gastric cancer (EBVnGC). In comparison with EBVnGCs, EBVaGCs overexpress a number of immune regulatory genes to help form an immunosuppressive tumor microenvironment (TME), have improved prognosis, and overall have an "immune-hot" phenotype. This review provides an overview of the histopathology, clinical features and clinical outcomes of EBVaGCs. We also summarize the differences between the TMEs of EBVaGCs and EBVnGCs, which includes significant differences in cell composition and immune infiltration. A list of available EBVaGC and EBVnGC gene expression datasets and computational tools are also provided within this review. Finally, an overview is provided of the various chemo- and immuno-therapeutics available in treating gastric cancers (GCs), with a focus on EBVaGCs.

Isothiocyanates attenuate immune checkpoint blockage therapy in gastric cancer via induction of PD-L1 expression

The PD-1/PD-L1 immune checkpoint blockade therapy has shown revolutionary efficacy in the treatment of multiple cancers including gastric cancer. Isothiocyanates play important roles in cancer cell suppression and immunomodulation. However, the effects of isothiocyanates on immune checkpoint inhibitors are poorly understood in gastric cancer. The influence of three major isothiocyanates (sulforaphane, phenylethyl isothiocyanate, and benzhydryl isothiocyanate) on gastric cancer cell growth and PD-L1 expression was investigated. Syngeneic mouse models were administered by isothiocyanates and anti-PD-L1 monoclonal antibody, and the anti-tumor effects were assessed. The expression of PD-L1, proportion of lymphocytes and serum cytokine levels were detected to explore the underlying mechanisms. We found that PD-L1 expression was significantly induced by isothiocyanates which was associated with TAp63α up-regulation. We further revealed that TAp63α promoted PD-L1 through transcriptional activation. Combination treatment of isothiocyanates and anti-PD-L1 therapy weakened the sensitivity of gastric cancer cells to anti-PD-L1 drug. Moreover, in vivo studies illustrated that the interference effects of isothiocyanates on anti-PD-L1 antibody were related to PD-L1 expression and decreased infiltrating T lymphocytes in tumor bearing mouse hosts. Our findings provide novel insights as isothiocyanates could interfere with the successful application of immunotherapy in gastric cancer.

Prognostic Value of LHFPL Tetraspan Subfamily Member 6 (LHFPL6) in Gastric Cancer: A Study Based on Bioinformatics Analysis and Experimental Validation

Purpose

The identification of biomarkers and effective therapeutic targets for gastric cancer (GC), the most common cause of cancer-related deaths around the world, is currently a major focus in research. Here, we examined the utility of LHFPL6 as a prognostic biomarker and therapeutic target for GC.

Methods

We explored the clinical relevance, function, and molecular role of LHFPL6 in GC using the MethSurv, cBioPortal, TIMER, Gene Expression Profiling Interactive Analysis, ONCOMINE, MEXPRESS, and EWAS Atlas databases. The GSE118919, GSE29272, and GSE13861 datasets were used for differential expression analysis. Using The Cancer Genome Atlas, we developed a Cox regression model and assessed the clinical significance of LHFPLs. In addition, we used the “CIBERSORT” algorithm to make reliable immune infiltration estimations. Western blot and immunohistochemistry were used to examine protein expression. Cell migration and invasion were assessed using transwell experiments. THP-1-derived macrophages and GC cells were co-cultured in order to model tumor–macrophage interactions in vitro. The levels of CD206 and CD163 were measured using immunofluorescence assays. The results were visualized with the “ggplot2” and “circlize” packages.

Results

Our results showed that in GC, LHFPL6 overexpression was significantly associated with a poor prognosis. Our findings also suggested that LHFPL6 may be involved in the activation of the epithelial–mesenchymal transition. Furthermore, LHFPL6 expression showed a positive correlation with the abundance of M2 macrophages, which are potent immunosuppressors.

Conclusion

LHFPL6 could be a prognostic biomarker and therapeutic target for GC.

A novel strategy for combination of clofarabine and pictilisib is synergistic in gastric cancer

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Drug sensitivity testing identified novel drugs like clofarabine effective in treating gastric cancer.

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mRNA sequencing can be used to identify agents with synergistic activity to a reference compound.

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Pictilisib sensitizes gastric cancer to clofarabine treatment through AKT inhibition.

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The combination of clofarabine and pictilisib inhibits tumor growth in cell lines and PDX models.

Gastric cancer (GC) is frequently characterized by resistance to standard chemotherapeutic regimens and poor clinical outcomes. We aimed to identify a novel therapeutic approach using drug sensitivity testing (DST) and our computational SynerySeq pipeline. DST of GC cell lines was performed with a library of 215 Federal Drug Administration (FDA) approved compounds and identified clofarabine as a potential therapeutic agent. RNA-sequencing (RNAseq) of clofarabine treated GC cells was analyzed according to our SynergySeq pipeline and identified pictilisib as a potential synergistic agent. Clonogenic survival and Annexin V assays demonstrated increased cell death with clofarabine and pictilisib combination treatment (P<0.01). The combination induced double strand breaks (DSB) as indicated by phosphorylated H2A histone family member X (γH2AX) immunofluorescence and western blot analysis (P<0.01). Pictilisib treatment inhibited the protein kinase B (AKT) cell survival pathway and promoted a pro-apoptotic phenotype as evidenced by quantitative real time polymerase chain reaction (qRT-PCR) analysis of the B-cell lymphoma 2 (BCL2) protein family members (P<0.01). Patient derived xenograft (PDX) data confirmed that the combination is more effective in abrogating tumor growth with prolonged survival than single-agent treatment (P<0.01). The novel combination of clofarabine and pictilisib in GC promotes DNA damage and inhibits key cell survival pathways to induce cell death beyond single-agent treatment.

Narrative review of pembrolizumab for the treatment of esophageal cancer: evidence and outlook

Objective

Based on the current evidence, review the efficacy and safety profile of pembrolizumab, along with its shortcomings, in an effort to define future research directions.

Background

The survival outcome of esophageal cancer (EC) is poor, especially in patients with advanced stage. Palliative surgery, chemotherapy, radiotherapy and chemoradiotherapy have limited efficacy in prolonging the survival time. Currently, immunotherapies, including adoptive cell therapy-based, antibody-based, and vaccine-based therapies, are attracting considerable attention. The mechanism of immunotherapy lies in the modification of immune response and prevention of immune escape. Immunomodulatory agents can block the programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) pathway, thereby allowing lymphocytes to attack tumor cells. This class of drugs has the potential to treat a variety of tumors and may substantially improve overall survival (OS) in some patients. Multiple clinical trials have shown that pembrolizumab has good efficacy and safety, enhances the EC treatment paradigm, and has even become the first-line treatment of choice for patients with PD-L1-positive recurrent or metastatic EC.

Methods

We reviewed the results of clinical trials of pembrolizumab for EC and gastroesophageal cancer presented at Embase, PubMed, the American Society of Clinical Oncology (ASCO) annual meetings, and the Cochrane Central Register of Controlled Trials.

Conclusions

Pembrolizumab has good efficacy and tolerability profiles, and has emerged as a second-line option for the treatment of PD-L1-positive locally advanced or metastatic ESCC. Pembrolizumab has many promising applications, and further investigations into its mechanisms should be conducted.

Hopes and failures in front-line advanced HER2-positive gastric cancer therapy

Human epidermal growth-factor receptor 2 (HER2) was an important therapeutic target in gastric cancer. Through the last decade, strategy with trastuzumab-based chemotherapy remains the first-line standard of treatment in advanced HER2-positive gastric cancer. Based on the Trastuzumab for Gastric Cancer trial, trastuzumab plus systemic chemotherapy of cisplatin and fluoropyrimidine as the backbone was established as the first-line therapy in advanced HER2-positive gastric cancer. Since then, studies have explored the optimization of the front-line strategy, including the dose of trastuzumab, chemotherapy regimen and maintenance therapy. A large number of clinical trials were conducted to explore the optimal front-line therapy regimens, such as lapatinib and pertuzumab. Safe and effective first-line regimens are still lacking. Recently, two phase II studies of combining immune checkpoint inhibitor in first-line treatment of advanced HER2-positive gastric cancer showed promising results. The progress of immunotherapy has gradually promoted the development of front-line treatment of advanced HER2-positive gastric cancer to potential chemotherapy-free strategies. Therefore, this article reviewed these significant clinical trials and focus on the front-line treatment strategies for HER2-positive gastric cancer.

Treatment Strategies of Gastric Cancer-Molecular Targets for Anti-angiogenic Therapy: a State-of-the-art Review

Purpose

Recent studies have suggested that molecular targets for the anti-angiogenic therapy might constitute a basis for additional therapy in gastric cancer treatment. A vast number of molecules, receptors, pathways, specific interactions, and thus strategies that target gastric cancer angiogenesis specifically have been reported in numerous research articles and clinical trials.

Methods

We conducted a systematic literature review of molecularly targeted treatment strategies in gastric cancer on the following databases—PubMed, Google Scholar, and Scopus—on September 20, 2020. Multiple articles and evaluations were searched for studies reporting newly found and promising molecular anti-angiogenic therapy pathways. Eventually, 39 articles regarding the anti-angiogenic therapy in gastric cancer were included in the final analysis.

Results

As a consequence of the release of the pro-angiogenic molecules from the tumour cells, gastric cancer presents high angiogenic capability. Therefore, potential schemes for future treatment strategies include the decrease of the process ligands as well as the expression of their receptors. Moreover, the increase in the angiogenic inhibitor levels and direct aim for the inner walls of the endothelial cells appear as a promising therapeutic strategy. Beyond that, angiogenesis process inhibition seems to indirectly exaggerate the effects of chemotherapy in the considered patients.

Conclusions

The anti-angiogenic treatment in gastric cancer patients evaluates its significance especially in the early stages of the malignancy. The studies conducted so far show that most of the meaningful angiogenic factors and receptors with the potential molecular pathways should be further evaluated since they could potentially play a substantial role in future therapies.

Nanobodies targeting immune checkpoint molecules for tumor immunotherapy and immunoimaging (Review)

The immune checkpoint blockade is an effective strategy to enhance the anti-tumor T cell effector activity, thus becoming one of the most promising immunotherapeutic strategies in the history of cancer treatment. Several immune checkpoint inhibitor have been approved by the FDA, such as anti-CTLA-4, anti-PD-1, anti-PD-L1 monoclonal antibodies. Most tumor patients benefitted from these antibodies, but some of the patients did not respond to them. To increase the effectiveness of immunotherapy, including immune checkpoint blockade therapies, miniaturization of antibodies has been introduced. A single-domain antibody, also known as nanobody, is an attractive reagent for immunotherapy and immunoimaging thanks to its unique structural characteristic consisting of a variable region of a single heavy chain antibody. This structure confers to the nanobody a light molecular weight, making it smaller than conventional antibodies, although remaining able to bind to a specific antigen. Therefore, this review summarizes the production of nanobodies targeting immune checkpoint molecules and the application of nanobodies targeting immune checkpoint molecules in immunotherapy and immunoimaging.

LncRNA NUTM2A-AS1 positively modulates TET1 and HIF-1A to enhance gastric cancer tumorigenesis and drug resistance by sponging miR-376a

Long noncoding RNA NUTM2A‐AS1 has been shown to be dysregulated in non‐small cell lung carcinoma. To date, it is unclear whether NUTM2A‐AS1 plays a role in gastric cancer progression. The purpose of this study is to elucidate the molecular mechanism of the role of NUTM2A‐AS1 in gastric cancer. mRNA and protein levels were measured by RT‐qPCR and western blot methods. Invasion ability was examined by transwell assay. Cell viability was determined by MTT assay. Dual‐luciferase assay, RNA pull down, and RNA immunoprecipitation were used to confirm direct binding of between miR‐376a and NUTM2A‐AS1 or TET1. Xenografting tumor assay and TCGA analysis showed the contributory role of NUTM2A‐AS1 in vivo and human clinical setting. Our results suggested that NUTM2A‐AS1 promoted cell viability, invasion, and drug resistance of gastric cancer cells, which was largely rescued by miR‐376a. More interestingly, TET1 and HIF‐1A were negatively regulated by miR‐376a. TET1 could interact with HIF‐1A to modulate PD‐L1. Finally, we revealed that PD‐L1 was key to NUTM2A‐AS1‐ and miR‐376a‐mediated tumorigenesis and drug resistance. In summary, our conclusions facilitate us understand the underlying mechanism and develop novel treatment strategy for gastric cancer.

Immune checkpoint inhibitor combination therapy for gastric cancer: Research progress

Gastric cancer is one of the most common types of cancer; notably, gastric cancer is one of the top five malignancies with regards to incidence and mortality rates. The symptoms of early gastric cancer are not typical, exhibiting only slight upper abdominal discomfort. When the symptoms become more obvious, the lesion has usually progressed to an advanced stage. Notably, >90% of inpatients already have locally advanced or metastatic gastric cancer at the time of initial diagnosis, with limited treatment options for advanced gastric cancer. These options include chemotherapy, targeted therapy and immune checkpoint inhibitors (ICIs). With regards to ICIs, the clinical benefit of monotherapy for advanced gastric cancer is limited; however, combinations of ICIs and other therapies may have clinical benefit. Relevant clinical studies have demonstrated that combinations of ICIs with chemotherapy, anti-vascular targeted therapy or other molecular targeted therapies, and the use of two ICIs, improve outcomes for patients with advanced gastric cancer. This article is a review of progress in the use of ICIs in combination with other therapies for the treatment of gastric cancer. The purpose of this article was to advance gastric cancer immunotherapy and to improve the overall therapeutic benefit for patients with advanced gastric cancer.

Patient-Derived Orthotopic Xenograft models in gastric cancer: a systematic review

Patient-Derived Xenografts (PDXs) are, so far, the best preclinical model to validate targets and predictors of response to therapy. While subcutaneous implantation very rarely allows metastatic dissemination, orthotopic implantation (Patient-Derived Orthotopic Xenograft-PDOX) increases metastatic capability. Using a modified tool to analyze model validity, we performed a systematic review of Embase, PubMed, and Web of Science up to December 2018 to identify all original publications describing gastric cancer (GC) PDOXs. We identified ten studies of PDOX model validation from January 1981 to December 2018 that fulfilled the inclusion and exclusion criteria. Most models (70%) were derived from human GC cell lines rather than tissue fragments. In 90% of studies, the implantation was performed in the subserosal layer. Tumour engraftment rate ranged from 0 to 100%, despite the technique. Metastases were observed in 40% of PDOX models implanted into the subserosal layer, employing either cell suspension or cell line-derived tumour fragments. According to our modified model validity tool, half of the studies were defined as unclear because one or more validation criteria were not reported. Available GC PDOX models are not adequate according to our model validity tool. There is no demonstration that the submucosal site is more effective than the subserosal layer, and that tissue fragments are better than cell suspensions for successful engraftment and metastatic spread. Further studies should strictly employ model validity tools and large samples with orthotopic implant sites mirroring as much as possible the donor tumour characteristics.

Induction/reversal of drug resistance in gastric cancer by non-coding RNAs (Review)

Gastric cancer (GC) is one of the most prevalent and malignant types of cancer worldwide. In China, it is the second most common type of cancer and the malignancy with the highest incidence and mortality rate. Chemotherapy for GC is not always effective due to the development of drug resistance. Drug resistance, which is frequently observed in GC, undermines the success rate of chemotherapy and the survival of patients with GC. The dysregulation of non‑coding RNAs (ncRNAs), primarily microRNAs (miRNAs or miRs) and long non‑coding RNAs (lncRNAs), is involved in the development of GC drug resistance via numerous mechanisms. These mechanisms contribute to the involvement of a large and complex network of ncRNAs in drug resistance. In this review, we focus on and summarize the latest research on the specific mechanisms of action of miRNAs and lncRNAs that modulate drug resistance in GC. In addition, we discuss future prospects and clinical applications of ncRNAs as potential targeted therapies against the chemoresistance of GC.