Upregulation of soluble B7-H3 in NSCLC-derived malignant pleural effusion: A potential diagnostic biomarker correlated with NSCLC staging

Higher serum sPD-L1 levels after radiotherapy indicate poor outcome in hepatocellular carcinoma patients

BACKGROUND

Our preclinical research reveals that radiotherapy (RT) promoted PD-L1 upregulation in tumor tissues and that higher PD-L1 after RT worsened the prognosis through immunosuppression. We sought to validate our experimental results in clinical cohorts and promote clinical application.

PATIENTS AND METHODS

In cohort 1, formalin-fixed paraffin-embedded samples were obtained from 46 HCC patients, 23 of whom received preoperative RT and the other 23 received direct surgery. A prospectively collected database contained 122 HCC patients treated with liver RT were enrolled in cohort 2. Blood samples were taken a day before and two weeks after RT. Patients in cohort 2 were further divided into two groups, exploration (73 patients) and validation (49 patients) groups.

RESULTS

In cohort 1, RT increased the expression of PD-L1 in tumor tissues (p = 0.001), and PD-L1 levels were associated with decreased cytotoxic T-cell infiltration and a trend toward poor prognosis (p = 0.14). Moreover, PD-L1 expression in tumor tissue positively correlated with soluble (s) PD-L1 in serum (R = 0.421, p = 0.046). Then, in cohort 2, we revealed RT increased sPD-L1 in serum (p < 0.001), which was associated with the number of circulating CD8+ T cells (R = -0.24, p = 0.036), indicating poor survival. Furthermore, patients with higher rate of sPD-L1 increase after RT have better treatment response (p < 0.001), PFS (p = 0.032) and OS (p = 0.045).

CONCLUSION

Higher post-RT serum sPD-L1, which may potentiate immune suppression effects, indicates a poor prognosis for HCC patients treated with RT.

Lung adenocarcinoma patients with malignant pleural effusions in hot adaptive immunity status have a longer overall survival

Malignant pleural effusion (MPE) is a common complication of lung adenocarcinoma (LADC) which is associated with a dismal prognosis. We investigated the prognostic role of PD-L1 and other immunomodulators expression in the immune compartment of MPE immune composition. MPE cytologic cell blocks of 83 LADC patients were analysed for the mRNA expression of 770 cancer-immune genes by the NanoString nCounter platform. The expression of relevant immune cell lineage markers was validated by immunohistochemistry (IHC) using quantitative pathology. The mRNA immune profiling identified four MPE patient clusters (C). C1/2 (adaptive+, hot) showed better overall survival (OS) than C3/4 (adaptive-, cold). Additionally, cold immunity profiles (adaptive-), C4 (innate+) were associated with worse OS than C3 (innate-). High PD-L1 expression was linked to the regulation of T cell activation and interferon signalling pathways. Genes of pattern recognition receptor and type I interferon signalling pathways were specifically upregulated in the long-survival (≥90 days) patient group. Moreover, immunomodulators were co-activated and highly expressed in hot adaptive immunity patient clusters, whereas CD274 (PD-L1), TNFRSF9 (4-1BB), VEGFA (VEGF-A) and CD276 (B7-H3) were upregulated in the groups referred as cold. The patient cluster, age and PD-L1 expression were independent prognosticators for LADC MPE patients (p-value < 0.05). Our study sheds light on the variances of immune contexture regarding different PD-L1 expression and survival conditions. It revealed four distinct prognostic patient clusters with specific immune cell components and immunomodulator expression profiles, which, collectively, is supportive for future therapeutic and prognosis for cancer management.

Biological Characteristics and Clinical Significance of Soluble PD-1/PD-L1 and Exosomal PD-L1 in Cancer

The immune checkpoint pathway consisting of the cell membrane-bound molecule programmed death protein 1 (PD-1) and its ligand PD-L1 has been found to mediate negative regulatory signals that effectively inhibit T-cell proliferation and function and impair antitumor immune responses. Considerable evidence suggests that the PD-1/PD-L1 pathway is responsible for tumor immune tolerance and immune escape. Blockage of this pathway has been found to reverse T lymphocyte depletion and restore antitumor immunity. Antagonists targeting this pathway have shown significant clinical activity in specific cancer types. Although originally identified as membrane-type molecules, several other forms of PD-1/PD-L1 have been detected in the blood of cancer patients, including soluble PD-1/PD-L1 (sPD-1/sPD-L1) and exosomal PD-L1 (exoPD-L1), increasing the composition and functional complications of the PD-1/PD-L1 signaling pathway. For example, sPD-1 has been shown to block the PD-1/PD-L immunosuppressive pathway by binding to PD-L1 and PD-L2, whereas the role of sPD-L1 and its mechanism of action in cancer remain unclear. In addition, many studies have investigated the roles of exoPD-L1 in immunosuppression, as a biomarker for tumor progression and as a predictive biomarker for response to immunotherapy. This review describes the molecular mechanisms underlying the generation of sPD-1/sPD-L1 and exoPD-L1, along with their biological activities and methods of detection. In addition, this review discusses the clinical importance of sPD-1/sPD-L1 and exoPD-L1 in cancer, including their predictive and prognostic roles and the effects of treatments that target these molecules.

B7H3 expression and significance in idiopathic pulmonary fibrosis

The clinical significance of B7H3 (CD276) and its cleavage product soluble B7H3 (sB7H3) in idiopathic pulmonary fibrosis (IPF) is unknown. Mounting evidence suggests the potential utility of peripheral blood myeloid cell enumeration to predict disease outcome and indicate active lung disease. Here we hypothesized that sB7H3 is involved in regulation of circulating myeloid cells in pulmonary fibrosis. In support of this possibility, both plasma sB7H3 and B7H3+ cells were elevated in IPF patient blood samples, which correlated negatively with lung function. To analyze its function, the effects of sB7H3 on naïve or bleomycin-treated mice were examined. The results revealed that sB7H3 injection induced an influx of myeloid-derived suppressor cells (MDSCs) and Ccl2 expression in lung tissue of naïve mice, accompanied by enhanced overall inflammation. Additionally, sB7H3 caused accumulation of MDSCs in bone marrow with increased expression of inflammatory cytokines. Notably, in vitro assays revealed chemotaxis of MDSCs to sB7H3, which was dependent on TLT-2 (TREML2), a putative receptor for sB7H3. Thus, increased circulating sB7H3 and/or B7H3+ cells in IPF patient blood samples correlated with lung function decline and potential immunosuppressive status. The correlation of sB7H3 with deterioration of lung function might be due to its ability to enhance inflammation and recruitment of MDSCs into the lung and their expansion in the bone marrow, and thus potentially contribute to IPF exacerbation. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Targeting the immune checkpoint B7-H3 for next-generation cancer immunotherapy

Immune checkpoint inhibitors (ICIs) for programmed death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) have become preferred treatment strategies for several advanced cancers. However, response rates for these treatments are limited, which encourages the search for new ICI candidates. Recent reports have underscored significant roles of B7 homolog 3 protein (B7-H3) in tumor immunity and disease progression. While its multifaceted roles are being elucidated, B7-H3 has already entered clinical trials as a therapeutic target. In this review, we overview the recent results of clinical trials evaluating the antitumor activity and safety of B7-H3 targeting drugs. On this basis, we also discuss the challenges and opportunities arising from the application of these drugs. Finally, we point out current gaps to address in the understanding of B7-H3 function and regulation in order to fully unleash the future clinical utility of B7-H3-based therapies for the treatment of cancer.

Soluble B7-CD28 Family Inhibitory Immune Checkpoint Proteins and Anti-Cancer Immunotherapy

Co-inhibitory B7-CD28 family member proteins negatively regulate T cell responses and are extensively involved in tumor immune evasion. Blockade of classical CTLA-4 (cytotoxic T lymphocyte-associated antigen-4) and PD-1 (programmed cell death protein-1) checkpoint pathways have become the cornerstone of anti-cancer immunotherapy. New inhibitory checkpoint proteins such as B7-H3, B7-H4, and BTLA (B and T lymphocyte attenuator) are being discovered and investigated for their potential in anti-cancer immunotherapy. In addition, soluble forms of these molecules also exist in sera of healthy individuals and elevated levels are found in chronic infections, autoimmune diseases, and cancers. Soluble forms are generated by proteolytic shedding or alternative splicing. Elevated circulating levels of these inhibitory soluble checkpoint molecules in cancer have been correlated with advance stage, metastatic status, and prognosis which underscore their broader involvement in immune regulation. In addition to their potential as biomarker, understanding their mechanism of production, biological activity, and pathological interactions may also pave the way for their clinical use as a therapeutic target. Here we review these aspects of soluble checkpoint molecules and elucidate on their potential for anti-cancer immunotherapy.

Evaluation of the role of soluble B7-H3 in association with membrane B7-H3 expression in gastric adenocarcinoma

BACKGROUND AND OBJECTIVE

Gastric adenocarcinoma (GAC) is one of the most common malignancies. Increasing data have indicated a correlation between soluble B7-H3 (sB7-H3) levels and tumor malignancies. In this study, we aim to investigate the level of soluble B7-H3 in serum of GAC patients. Further, we analyze the correlation between sB7-H3 level and tissue B7-H3 expression and explore the clinical evaluation value of sB7-H3 associated with pathological characteristics and prognosis of GAC patients.

METHODS

One hundred and twenty-eight serum and tissue samples of GAC 20 serum and tissue samples of gastritis patients and 77 serum, 5 tissue samples of healthy controls were collected. The serum levels of sB7-H3 were detected by Enzyme-linked immunosorbent assay (ELISA), while the expression of membrane B7-H3 (mB7-H3) and Ki67 were evaluated by immunohistochemistry. The correlation between sB7-H3 and mB7-H3, sB7-H3 and Ki67, sB7-H3 or mB7-H3 and clinical features were analyzed by Pearson's Chi-square test.

RESULTS

Both serum level of sB7-H3 and tissue B7-H3 of GAC patients were significantly higher than those of gastritis patients and healthy controls. sB7-H3 level was correlated with total B7-H3 expression in tissues (r= 0.2801, P= 0.0014). Notably, the concentration of sB7-H3 was correlated with its expression of membrane form in tumor cells (r= 0.3251, P= 0.002) while not in stromal cells (r= 0.07676, P= 0.3891). Moreover, the levels of sB7-H3 in patients with TNM stage III/IV or with Infiltration depth T3/T4 or with lymph node metastasis were significantly higher than those of patients with TNM stage I/II (P= 0.0020) or with Infiltration depth T1/T2 (P= 0.0169) or with no lymph node metastasis (P= 0.0086). Tumor B7-H3 score, but not stromal B7-H3 score, in patients with TNM stage III/IV or with lymph node metastasis was significantly higher than those with TNM stage I/II (P= 0.0150) or with no lymph node metastasis (P= 0.182).

CONCLUSIONS

Soluble B7-H3 level may reflect the tissue B7-H3 expression on tumor cells of GAC tissues. Elevated level of sB7-H3 in serum suggests poor clinical pathological characteristics of GAC patients.

Emerging immunotherapy targets in lung cancer

Immunotherapy has become the mainstay for lung cancer treatment, providing sustained therapeutic responses and improved prognosis compared with those obtained with surgery, chemotherapy, radiotherapy, and targeted therapy. It has the potential for anti-tumor treatment and killing tumor cells by activating human immunity and has moved the targets of anti-cancer therapy from malignant tumor cells to immune cell subsets. Two kinds of immune checkpoints, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death-1 (PD-1)/programmed death ligand 1 (PD-L1), are the main targets of current immunotherapy in lung cancer. Despite the successful outcomes achieved by immune checkpoint inhibitors, a small portion of lung cancer patients remain unresponsive to checkpoint immunotherapy or may ultimately become resistant to these agents as a result of the complex immune modulatory network in the tumor microenvironment. Therefore, it is imperative to exploit novel immunotherapy targets to further expand the proportion of patients benefiting from immunotherapy. This review summarizes the molecular features, biological function, and clinical significance of several novel checkpoints that have important roles in lung cancer immune responses beyond the CTLA-4 and PD-1/PD-L1 axes, including the markers of co-inhibitory and co-stimulatory T lymphocyte pathways and inhibitory markers of macrophages and natural killer cells.

B7-H3 and digestive system cancers

Digestive system cancers (DSC) are the most common cancers worldwide and often associated with poor prognosis because of their characteristics of invasive and metastatic. Thus, it is particularly necessary to find novel molecular targets for early diagnosis, as well as targeted treatment of DSC. B7-H3, which was previously referred to as a modulatory ligand that regulate T-cell-mediated immune reaction, is a B7-family member of co-stimulatory biomolecules, and in recent years it was found that its concentration was remarkably up modulated in serum, as well as tissues of DSC patients. Numerous studies have documented that B7-H3 has a vital function in the DSC. Herein, we summarize the current literature on diagnosis and prognosis potential of B7-H3 in DSC including those of the esophagus, gastric, liver, pancreas, and colon.

Pleural biomarkers in diagnostics of malignant pleural effusion: a narrative review

Although cytology and pleural biopsy of pleural effusion (PE) are the gold standards for diagnosing malignant pleural effusion (MPE), these tools’ diagnostic accuracy is plagued by some limitations such as low sensitivity, considerable inter-observer variation and invasiveness. The assessment of PE biomarkers may hence be seen as an objective and non-invasive diagnostic alternative in MPE diagnostics. In this review, we summarize the characteristics and diagnostic accuracy of available PE biomarkers, including carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigens 125 (CA125), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 15-3 (CA15-3), a fragment of cytokeratin 19 (CYFRA 21-1), chitinase-like proteins (CLPs), vascular endothelial growth factor (VEGF) and its soluble receptor, endostatin, calprotectin, cancer ratio, homocysteine, apolipoprotein E (Apo-E), B7 family members, matrix metalloproteinase (MMPs) and tissue-specific inhibitors of metalloproteinases (TIMPs), reactive oxygen species modulator 1 (Romo1), tumor-associated macrophages (TAMs) and monocytes, epigenetic markers (e.g., cell-free microRNA and mRNA). We summarized the evidence from systematic review and meta-analysis for traditional tumor markers’ diagnostic accuracy. According to the currently available evidence, we conclude that the traditional tumor markers have high specificity (around 0.90) but low sensitivity (around 0.50). The diagnostic accuracy of novel tumor markers needs to be validated by further studies. None of these tumor biomarkers would have sufficient diagnostic accuracy to confirm or exclude MPE when used alone. A multi-biomarker strategy, also encompassing the use of artificial intelligence algorithms, may be a valuable perspective for improving the diagnostic accuracy of MPE.

B7-H3 Immune Checkpoint Protein in Human Cancer

B7-H3 belongs to the B7 family of immune checkpoint proteins, which are important regulators of the adaptive immune response and emerging key players in human cancer. B7-H3 is a transmembrane protein expressed on the surface of tumor cells, antigen presenting cells, natural killer cells, tumor endothelial cells, but can also be present in intra- and extracellular vesicles. Additionally, B7-H3 may be present as a circulating soluble isoform in serum and other body fluids. B7-H3 is overexpressed in a variety of tumor types, in correlation with poor prognosis. B7-H3 is a promising new immunotherapy target for anti-cancer immune response, as well as a potential biomarker. Besides its immunoregulatory role, B7-H3 has intrinsic pro-tumorigenic activities related to enhanced cell proliferation, migration, invasion, angiogenesis, metastatic capacity and anti-cancer drug resistance. B7-H3 has also been found to regulate key metabolic enzymes, promoting the high glycolytic capacity of cancer cells. B7-H3 receptors are still not identified, and little is known about the molecular mechanisms underlying B7-H3 functions. Here, we review the current knowledge on the involvement of B7-H3 in human cancer.

Prognostic Immune Cell Profiling of Malignant Pleural Effusion Patients by Computerized Immunohistochemical and Transcriptional Analysis

Malignant pleural effusion (MPE) is a severe condition of advanced tumors without effective therapy. We used digitalized immunohistochemical and transcriptional approaches to investigate the prognostic influence of immune cells and expression variance of associated immunomodulatory molecules in MPE. Cytology tissue microarrays were constructed from MPE cell blocks of 155 patients with five tumor entities. Immune cells lineage markers were quantified by computational cytopathology on immunohistochemistry. mRNA expression analysis of nine lineage markers and 17 immunomodulators was performed by NanoString. Immunohistochemically quantified high B cells to leukocytes ratio (hazard ratio (HR) = 0.70, p-value = 0.043) and low neutrophils to leukocytes ratio (HR = 1.78, p-value = 0.003) were favorable prognosticators for overall survival independent of tumor entity. Correspondingly, patients with high B cells but low neutrophils gene expression signature showed longer median overall survival of 500 days (HR = 2.29, p-value = 0.009). Regarding targetable molecule expressions, lung adenocarcinomas were characterized by high PD-L1, but mesothelioma by high LAG-3. Ovarian carcinoma was least immunogenic. Independent of tumor entity, the condition of the immune system in MPE liquids is able to provide additional prognostic cytologic information. Combined analysis of lineage specific markers and related immunomodulators may direct immune-based therapeutic decisions.

Molecular Characterization of a Long-Term Survivor Double Metastatic Non-Small Cell Lung Cancer and Pancreatic Ductal Adenocarcinoma Treated with Gefitinib in Combination with Gemcitabine Plus Nab-Paclitaxel and mFOLFOX6 as First and Second Line Therapy

The management of multiple primary cancers, an event not so infrequent in oncology practice, is a critical issue due to the lack of literature. In this study, we reported the case of a patient with non-small cell metastatic lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) who received gefitinib in combination with gemcitabine plus nab-paclitaxel and with mFOLFOX6 in first and second line, respectively. It achieved a progression-free survival and a28-months overall survival (OS) for NSCLC and PFS-1 and OS of 20 and 13 months, respectively for PDAC. Moreover, the combination of gefitinib and chemotherapy treatmentsshowed a good safety profile. Given the insignificant frequency of this case, we performed a molecular characterization of both neoplasms with the aim to investigate the existence of particular activated pathways and/or similar immunological mutations. It is interesting to note that two neoplasms shared a common mutation ofthe B7-H3 gene, with the consecutive impairment of its expressed protein. In both PDAC and NSCLC, the expression of this protein was associated with a worse survival rate. Since B7-H3 is an anti-apoptotic protein, the reduction of its expression or function should justify a pro-apoptotic activity with a leading justification of the long survival of the patient considered in this report.

Making cold malignant pleural effusions hot: driving novel immunotherapies

Malignant pleural effusions, arising from either primary mesotheliomas or secondary malignancies, heralds advanced disease and poor prognosis. Current treatments, including therapeutic thoracentesis and tube thoracostomy, are largely palliative. The immunosuppressive environment within the pleural cavity includes myeloid derived suppressor cells, T-regulatory cells, and dysfunctional T cells. The advent of effective immunotherapy with checkpoint inhibitors and adoptive cell therapies for lung cancer and other malignancies suggests a renewed examination of local and systemic therapies for this malady. Prior strategies reporting remarkable success, including instillation of the cytokine interleukin-2, perhaps coupled with checkpoint inhibitors, should be further evaluated in the modern era.

Soluble immune checkpoints in cancer: production, function and biological significance

Immune checkpoints play important roles in immune regulation, and blocking immune checkpoints on the cell membrane is a promising strategy in the treatment of cancer. Based on this, monoclonal antibodies are having much rapid development, such as those against CTLA-4 (cytotoxic T lymphocyte antigen 4) and PD-1 (programmed cell death protein 1).But the cost of preparation of monoclonal antibodies is too high and the therapeutic effect is still under restrictions. Recently, a series of soluble immune checkpoints have been found such as sCTLA-4 (soluble CTLA-4) and sPD-1 (soluble PD-1). They are functional parts of membrane immune checkpoints produced in different ways and can be secreted by immune cells. Moreover, these soluble checkpoints can diffuse in the serum. Much evidence has demonstrated that these soluble checkpoints are involved in positive or negative immune regulation and that changes in their plasma levels affect the development, prognosis and treatment of cancer. Since they are endogenous molecules, they will not induce immunological rejection in human beings, which might make up for the deficiencies of monoclonal antibodies and enhance the utility value of these molecules. Therefore, there is an increasing need for investigating novel soluble checkpoints and their functions, and it is promising to develop relevant therapies in the future. In this review, we describe the production mechanisms and functions of various soluble immune checkpoint receptors and ligands and discuss their biological significance in regard to biomarkers, potential candidate drugs, therapeutic targets, and other topics.

Soluble B7-H3 (sB7-H3) is over-expressed in the serum of type 1 diabetes patients

Type 1 Diabetes (T1D) is an autoimmune disease resulting from insulin-secreting β-cells mediated by autoreactive T cells. We demonstrated increased level of sB7-H3 in T1D patients than in healthy control group. This result suggests that B7-H3 may be may be a promising biomarker associated with the pathogenesis of T1D.

B7-H3 in tumors: friend or foe for tumor immunity?

B7-H3 is a type I transmembrane co-stimulatory molecule of the B7 family. B7-H3 mRNA is widely distributed in most tissues; however, B7-H3 protein is not constitutively expressed. Few molecules have been shown to mediate the regulation of B7-H3 expression, and their regulatory mechanisms remain unexplored. Recently, TREM-like transcript 2 (TLT-2) has been identified as a potential receptor of B7-H3. However, TLT-2 may not be the only receptor of B7-H3, as B7-H3 has many contradictory roles. As a co-stimulatory molecule, B7-H3 increases the proliferation of both CD4+ and CD8+ T-cells and enhances cytotoxic T-cell activity. However, greatly increased T-cell proliferation and IL-2 levels have been observed in the absence of B7-H3. Thus far, it has been shown that various tumors test positive for B7-H3 expression and that B7-H3 levels correlate with tumor growth, invasion, metastasis, malignant stage, and recurrence rate. Furthermore, transfection of cells with a B7-H3 plasmid and treatment with monoclonal antibodies to block B7-H3 are the main immunotherapeutic strategies for cancer treatment. Several groups have generated anti-B7-H3 antibodies and observed tumor growth suppression in vitro and in vivo. Therefore, it is likely that B7-H3 plays an important role in cancer diagnosis and treatment, aside from its role as a co-stimulatory molecule.

Reduced sB7-H3 Expression in the Peripheral Blood of Systemic Lupus Erythematosus Patients

Both membrane-bound and soluble forms of costimulatory molecules play important roles in immune-regulatory networks. B7-H3, a member of the B7 family, has been found with aberrant expression in tumors and infectious disease. However, the significance of sB7-H3 expression in systemic lupus erythematosus (SLE) has not been investigated. Using the peripheral blood of 78 SLE patients, we established a comprehensive database containing clinical data and relevant laboratory tests. We found that sB7-H3 expression in SLE patients was significantly lower compared with the healthy individuals. In addition, sB7-H3 levels in the patients were positively correlated with the disease activity as indicated by SLE disease activity index score, rashes, fever, and inflammatory cytokines. Moreover, sB7-H3 was associated with the counts of red blood cells and hemoglobin. Our findings suggest that sB7-H3 might counteract the aberrant immune response and potentially serve as a monitoring indicator of disease progression and therapeutic target in SLE treatment.