• Molecules and Cells
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• v.44 no.5
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• pp.363-373
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• 2021

Immune checkpoint inhibitors have changed the paradigm of treatment options for non-small cell lung cancer (NSCLC). Monoclonal antibodies targeting programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) have gained wide attention for their application, which has been shown to result in prolonged survival. Nevertheless, only a limited subset of patients show partial or complete response to PD-1 therapy, and patients who show a response eventually develop resistance to immunotherapy. This article aims to provide an overview of the mechanisms of acquired resistance to anti-PD-1/PD-L1 therapy from the perspective of tumor cells and the surrounding microenvironment. In addition, we address the potential therapeutic targets and ongoing clinical trials, focusing mainly on NSCLC.

• Journal of Yeungnam Medical Science
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• v.38 no.4
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• pp.308-317
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• 2021

Cancer is the leading cause of death and is on the rise worldwide. Until 2010, the development of targeted treatment was mainly focused on the growth mechanisms of cancer. Since then, drugs with mechanisms related to tumor immunity, especially immune checkpoint inhibitors, have proven effective, and most pharmaceutical companies are striving to develop related drugs. Programmed cell death-1 and programmed cell death ligand-1 inhibitors have shown great success in various cancer types. They showed durable and sustainable responses and were approved by the U.S. Food and Drug Administration. However, the response to inhibitors showed low percentages of cancer patients; 15% to 20%. Therefore, combination strategies with immunotherapy and conventional treatments were used to overcome the low response rate. Studies on combination therapy have typically reported improvements in the response rate and efficacy in several cancers, including non-small cell lung cancer, small cell lung cancer, breast cancer, and urogenital cancers. The combination of chemotherapy or targeted agents with immunotherapy is one of the leading pathways for cancer treatment.

• Journal of Digestive Cancer Research
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• v.10 no.1
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• pp.22-30
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• 2022

Immune checkpoint inhibition has been established as a new treatment option for various types of carcinoma, and many clinical trials are being actively conducted as a treatment for advanced or metastatic gastric cancer, either as a monotherapy with an immune checkpoint inhibitor or as a combination therapy with standard chemotherapy. In the CheckMate-649 clinical trial to confirm the efficacy of the combination of nivolumab and chemotherapy (FP) in advanced gastric cancer and gastroesophageal junction cancer, nivolumab group showed improvement in overall survival in programmed death ligand 1-positive cancer patients compared with placebo group. Also, the combination therapy of pembrolizumab, trastuzumab and chemotherapy (FP) in first-line treatment was tested through the KEYNOTE-811 trial. The pembrolizumab group showed 22.7% of improvement in objective response rate compared with placebo group. Accordingly, the combination of nivolumab/pembrolizumab with standard chemotherapy was approved for the first-line treatment. In KEYNOTE-059 trials for patients with progressive disease after at least two lines of chemotherapy, pembrolizumab monotherapy showed improvement in objective response rate and overall survival, and the use of pembrolizumab was approved for the third-line or more treatment. In this article, we review the result of clinical trials related to immune checkpoint inhibitors that have been recently introduced in the treatment of gastric cancer.

• Radiation Oncology Journal
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• v.34 no.4
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• pp.250-259
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• 2016

Immune checkpoint blockades including monoclonal antibodies (mAbs) of cytotoxic T-lymphocyte antigen-4 (CTLA-4), programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1) have been emerged as a promising anticancer therapy. Several immune checkpoint blockades have been approved by US Food and Drug Administration (FDA), and have shown notable success in clinical trials for patients with advanced melanoma and non-small cell lung cancer. Radiotherapy is a promising combination partner of immune checkpoint blockades due to its potent pro-immune effect. This review will cover the current issue and the future perspectives for combined with radiotherapy and immune checkpoint blockades based upon the available preclinical and clinical data.

• Tuberculosis and Respiratory Diseases
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• v.87 no.1
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• pp.22-30
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• 2024

Tumor immune evasion is a complex process that involves various mechanisms, such as antigen recognition restriction, immune system suppression, and T cell exhaustion. The tumor microenvironment contains various immune cells involved in immune evasion. Recent studies have demonstrated that granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) induce immune evasion in lung cancer by modulating neutrophils and myeloid-derived suppressor cells. Here we describe the origin and function of G-CSF and GM-CSF, particularly their role in immune evasion in lung cancer. In addition, their effects on programmed death-ligand 1 expression and clinical implications are discussed.

• Tuberculosis and Respiratory Diseases
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• v.65 no.4
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• pp.343-350
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• 2008

PD-L1 is expressed in a variety of antigen-presenting cells and provides T cell tolerance via ligation with its receptor PD-1 and B7-1 on T cells. Stimulation with lipopolysaccharide (LPS) can increase the level of PD-L1 expression in B cells and macrophages, which suggests that this molecule plays a role in the immunosuppression observed in severe sepsis. The aim of this study was to identify which of the downstream pathways of TLR4 are involved in the up-regulation of PD-L1 by LPS in macrophages. Flow cytometry was used to examine the expression of PD-L1 in RAW 264.7 macrophages stimulated with LPS. The following chemical inhibitors were used to evaluate the role of each pathway: LY294002 for PI3K/Akt, SB202190 for p38 MAPK, and U0126 for MEK. LPS induced the expression of PD-L1 in a time- and dose-dependent manner. Transfection of siRNA for TLR4 suppressed the induction of PD-L1. Pretreatment with LY294002 and SB202190 decreased the level of PD-L1 expression but U0126 did not. Overall, the PI3K/Akt and p38 MAPK pathways are involved in the up-regulation of PD-L1 expression in RAW 264.7 macrophages stimulated with LPS.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.75.1-75.10
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• 2021

Background: Programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) have important roles in tumor evasion of the immune system. Objectives: This study aimed to assess the diagnostic utility of circulating PD-1 and PD-L1 levels in healthy dogs and dogs with tumors. Methods: Circulating PD-1 and PD-L1 levels in the serum of 71 dogs with tumors were compared with those of 52 healthy dogs by performing enzyme-linked immunosorbent assay (ELISA). Results: The ELISA results revealed higher circulating PD-1 and PD-L1 levels in dogs with tumors (2.9 [2.2-3.7] ng/mL; median [IQR] and 2.4 [1.4-4.4] ng/mL, respectively) than in healthy dogs (2.4 [1.9-3.0] ng/mL; p = 0.012 and 1.4 [0.9-2.1] ng/mL; p < 0.001, respectively). Especially, there was a significant difference in circulating PD-1 levels between healthy dogs and dogs with malignant epithelial tumors (2.4 [1.9-3.0] ng/mL and 3.1 [2.6-4.4] ng/mL, respectively; p < 0.01). In addition, there was a significant difference in circulating PD-L1 levels between healthy dogs and dogs with lymphomas (1.4 [0.9-2.1] ng/mL and 2.7 [1.6-5.8] ng/mL, respectively; p < 0.001). Conclusion: This study indicates that circulating PD-1 and PD-L1 have potential as tumor diagnostic biomarkers in dogs with tumors.

• BMB Reports
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• v.54 no.1
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• pp.12-20
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• 2021

In the last decade, we have witnessed an unprecedented clinical success in cancer immunotherapies targeting the programmed cell-death ligand 1 (PD-L1) and programmed cell-death 1 (PD-1) pathway. Besides the fact that PD-L1 plays a key role in immune regulation in tumor microenvironment, recently a plethora of reports has suggested a new perspective of non-immunological functions of PD-L1 in the regulation of cancer intrinsic activities including mesenchymal transition, glucose and lipid metabolism, stemness, and autophagy. Here we review the current understanding on the regulation of expression and intrinsic protumoral activity of cancer-intrinsic PD-L1.

• Journal of the Korean Society of Radiology
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• v.85 no.2
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• pp.394-408
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• 2024

Purpose To develop models to predict programmed death ligand 1 (PD-L1) expression in pulmonary squamous cell carcinoma (SCC) using CT. Materials and Methods A total of 97 patients diagnosed with SCC who underwent PD-L1 expression assay were included in this study. We performed a CT analysis of the tumors using pretreatment CT images. Multiple logistic regression models were constructed to predict PD-L1 positivity in the total patient group and in the 40 advanced-stage (≥ stage IIIB) patients. The area under the receiver operating characteristic curve (AUC) was calculated for each model. Results For the total patient group, the AUC of the 'total significant features model' (tumor stage, tumor size, pleural nodularity, and lung metastasis) was 0.652, and that of the 'selected feature model' (pleural nodularity) was 0.556. For advanced-stage patients, the AUC of the 'selected feature model' (tumor size, pleural nodularity, pulmonary oligometastases, and absence of interstitial lung disease) was 0.897. Among these factors, pleural nodularity and pulmonary oligometastases had the highest odds ratios (8.78 and 16.35, respectively). Conclusion Our model could predict PD-L1 expression in patients with lung SCC, and pleural nodularity and pulmonary oligometastases were notable predictive CT features of PD-L1.

• Journal of Gastric Cancer
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• v.24 no.1
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• pp.29-56
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• 2024

In recent years, remarkable progress has been made in the molecular profiling of gastric cancer. This progress has led to the development of various molecular classifications to uncover subtype-specific dependencies that can be targeted for therapeutic interventions. Human epidermal growth factor receptor 2 (HER2) is a crucial biomarker for advanced gastric cancer. The recent promising results of novel approaches, including combination therapies or newer potent agents such as antibody-drug conjugates, have once again brought attention to anti-HER2 targeted treatments. In HER2-negative diseases, the combination of cytotoxic chemotherapy and programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors has become the established standard of care in first-line settings. In the context of gastric cancer, potential biomarkers such as PD-L1 expression, Epstein-Barr virus, microsatellite instability, and tumor mutational burden are being considered for immunotherapy. Recently, promising results have been reported in studies on anti-Claudin18.2 and fibroblast growth factor receptor 2 treatments. Currently, many ongoing trials are aimed at identifying potential targets using novel approaches. Further investigations will be conducted to enhance the progress of these therapies, addressing challenges such as primary and acquired resistance, tumor heterogeneity, and clonal evolution. We believe that these efforts will improve patient prognoses. Herein, we discuss the current evidence of potential targets for systemic treatment, clinical considerations, and future perspectives.