Serum soluble B7-H4 is a prognostic marker for patients with non-metastatic clear cell renal cell carcinoma

Prognostic Value of B7H4 Expression in Patients with Solid Cancers: A Systematic Review and Meta-Analysis

V-set domain-containing T-cell activation inhibitor 1 (aliases VTCN1, B7H4) participates in tumour immune escape by delivering inhibitory signals to T cells. The purpose of this article was to assess the B7H4 prognostic value in solid cancers. Three databases were searched for relevant articles. The main endpoints were overall survival (OS), disease-specific survival (DSS), progression-free survival (PFS), recurrence-free survival (RFS), and disease-free survival (DFS). Appropriate hazard ratios (HRs) were pooled. The R studio software (version 4.0.3) was used for data analysis. Thirty-one studies met the inclusion criteria. High expression of B7H4 was associated with worse OS (HR = 1.52, 95% CI: 1.37-1.68) but not with DSS (HR = 1.14, 95% CI: 0.49-2.63), RFS (HR = 1.77, 95% CI: 0.75-4.18), DFS (HR = 1.29, 95% CI: 0.8-2.09), or PFS (HR = 1.71, 95% CI: 0.91-3.2) in patients with solid cancers. High expression of B7H4 is associated with a poorer prognosis in patients with solid cancers. B7H4 is a promising prognostic biomarker and immunotherapeutic target for various solid cancers because of its activity in cancer immunity and tumourigenesis.

Immune checkpoints and cancer immunotherapies: insights into newly potential receptors and ligands

Checkpoint markers and immune checkpoint inhibitors have been increasingly identified and developed as potential immunotherapeutic targets in various human cancers. Despite valuable efforts to discover novel immune checkpoints and their ligands, the precise roles of their therapeutic functions, as well as the broad identification of their counterpart receptors, remain to be addressed. In this context, it has been suggested that various putative checkpoint receptors can be induced upon activation. In the tumor microenvironment, T cells, as crucial immune response against malignant diseases as well as other immune central effector cells, such as natural killer cells, are regulated via co-stimulatory or co-inhibitory signals from immune or tumor cells. Studies have shown that exposure of T cells to tumor antigens upregulates the expression of inhibitory checkpoint receptors, leading to T-cell dysfunction or exhaustion. Although targeting immune checkpoint regulators has shown relative clinical efficacy in some tumor types, most trials in the field of cancer immunotherapies have revealed unsatisfactory results due to de novo or adaptive resistance in cancer patients. To overcome these obstacles, combinational therapies with newly discovered inhibitory molecules or combined blockage of several checkpoints provide a rationale for further research. Moreover, precise identification of their receptors counterparts at crucial checkpoints is likely to promise effective therapies. In this review, we examine the prospects for the application of newly emerging checkpoints, such as T-cell immunoglobulin and mucin domain 3, lymphocyte activation gene-3, T-cell immunoreceptor with Ig and ITIM domains (TIGIT), V-domain Ig suppressor of T-cell activation (VISTA), new B7 family proteins, and B- and T-cell lymphocyte attenuator, in association with immunotherapy of malignancies. In addition, their clinical and biological significance is discussed, including their expression in various human cancers, along with their roles in T-cell-mediated immune responses.

Prognostic Role of Soluble and Extracellular Vesicle-Associated PD-L1, B7-H3 and B7-H4 in Non-Small Cell Lung Cancer Patients Treated with Immune Checkpoint Inhibitors

The treatment of non-small cell lung cancer (NSCLC) has changed dramatically with the advent of immune checkpoint inhibitors (ICIs). Despite encouraging results, their efficacy remains limited to a subgroup of patients. Circulating immune checkpoints in soluble (s) form and associated with extracellular vesicles (EVs) represent promising markers, especially in ICI-based therapeutic settings. We evaluated the prognostic role of PD-L1 and of two B7 family members (B7-H3, B7-H4), both soluble and EV-associated, in a cohort of advanced NSCLC patients treated with first- (n = 56) or second-line (n = 126) ICIs. In treatment-naïve patients, high baseline concentrations of sPD-L1 (>24.2 pg/mL) were linked to worse survival, whereas high levels of sB7-H3 (>0.5 ng/mL) and sB7-H4 (>63.9 pg/mL) were associated with better outcomes. EV characterization confirmed the presence of EVs positive for PD-L1 and B7-H3, while only a small portion of EVs expressed B7-H4. The comparison between biomarker levels at the baseline and in the first radiological assessment under ICI-based treatment showed a significant decrease in EV-PD-L1 and an increase in EV-B7H3 in patients in the disease response to ICIs. Our study shows that sPD-L1, sB7-H3 and sB7-H4 levels are emerging prognostic markers in patients with advanced NSCLC treated with ICIs and suggests potential EV involvement in the disease response to ICIs.

The immunological role of b7-h4 in pregnant women with sars-cov2 infection

Problem

T‐cells are key players in fighting the coronavirus disease 2019 (COVID‐19). The checkpoint molecule B7‐H4, a member of the B7 family, can inhibit T‐cell activation and proliferation by inhibiting NF‐kb expression. We aimed to elucidate the immunological role of soluble B7‐H4 (sB7‐H4) and B7‐H4 in pregnant women suffered from an acute Sars‐Cov2 infection.

Methods

Expression levels of sB7‐H4 and cytokines were detected by enzyme linked immunosorbent assay. B7‐H4 and cytokines mRNA expression was analyzed by qPCR, and B7‐H4 and NF‐κb (p65) protein levels were investigated by western blot and immunofluorescence staining in placenta chorionic villous and decidual basalis tissues of COVID‐19 affected women and healthy controls.

Results

Fibrinoid necrosis in the periphery of placental villi was increased in the COVID‐19‐affected patients. sB7‐H4 protein in maternal and cord blood serum and IL‐6/IL‐10 were increased while leukocytes were decreased during SARS‐CoV‐2 infection. Serum sB7‐H4 level was increased according to the severity of SARS‐Cov‐2 infection. Cytokines (IL‐6, IL‐18, IL‐1β, TNF‐α), B7‐H4 mRNA and protein in the decidual basalis tissues of COVID‐19‐infected pregnant women were significantly increased compared to healthy controls. IL‐18 and IL‐1β were significantly increased in the placenta chorionic villous samples of COVID‐19 affected patients, while NF‐κb (p65) expression was decreased.

Conclusions

The expression of the immunological marker sB7‐H4 correlated with the severity of COVID‐19 disease in pregnant women. sB7‐H4 and B7‐H4 can be used to monitor the progression of COVID‐19 infection during pregnancy, and for evaluating of the maternal immune status.

B7-H4 Immune Checkpoint Protein Affects Viability and Targeted Therapy of Renal Cancer Cells

Targeted therapy in combination with immune checkpoint inhibitors has been recently implemented in advanced or metastatic renal cancer treatment. However, many treated patients either do not respond or develop resistance to therapy, making alternative immune checkpoint-based immunotherapies of potential clinical benefit for specific groups of patients. In this study, we analyzed the global expression of B7 immune checkpoint family members (PD-L1, PD-L2, B7-H2, B7-H3, B7-H4, B7-H5, B7-H6, and B7-H7) in human renal cancer cells (Caki-1, A-498, and 786-O cell lines) upon treatment with clinically relevant targeted drugs, including tyrosine kinase inhibitors (Axitinib, Cabozantinib, and Lenvatinib) and mTOR inhibitors (Everolimus and Temsirolimus). Gene expression analysis by quantitative PCR revealed differential expression patterns of the B7 family members in renal cancer cell lines upon targeted drug treatments. B7-H4 gene expression was upregulated after treatment with various targeted drugs in Caki-1 and 786-O renal cancer cells. Knocking down the expression of B7-H4 by RNA interference (RNAi) using small interfering RNA (siRNA) decreased renal cancer cell viability and increased drug sensitivity. Our results suggest that B7-H4 expression is induced upon targeted therapy in renal cancer cells and highlight B7-H4 as an actionable immune checkpoint protein in combination with targeted therapy in advanced renal cancer cases resistant to current treatments.

Association of Soluble B7-H4 and Circulating Tumor Cells in Blood of Advanced Epithelial Ovarian Cancer Patients

Introduction

Epithelial ovarian cancer (EOC) is the deadliest gynecologic malignancy worldwide. Reliable predictive biomarkers are urgently needed to estimate the risk of relapse and to improve treatment management. Soluble immune-checkpoints in EOC are promising molecules serving as prognostic biomarkers accessible via liquid biopsy. We thus, aimed at elucidating the role of sB7-H4 in EOC.

Material and Methods

We analyzed soluble serum B7-H4 (sB7-H4) using ELISA and circulating tumor cells (CTCs) in blood applying the AdnaTest OvarianCancer in 85 patients suffering from advanced EOC. Findings were correlated with clinical parameters as well as survival data.

Results

sB7-H4 was detectable in 14.1% patients, CTCs in 32.9% patients and simultaneous presence of CTCs and sB7-H4 was found in 7% patients, respectively. Although no association between sB7-H4 and CTC could be documented, each of them served as independent predictive factors for overall survival (OS).

Conclusion

sB7-H4 and CTCs are independent prognostic biomarkers for impaired survival in EOC. As they are easily accessible via liquid biopsy, they may be of potential benefit for the prediction of therapy response and survival for EOC patients.

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.

Establishment of a novel double-monoclonal antibody sandwich enzyme-linked immunosorbent assay (ELISA): tool for human B7-H4 detection in autoimmune diseases

B7-H4, one of the immunoregulatory proteins, plays an inhibitory role by inhibiting T cell proliferation and cytokine production. Nevertheless, the significance of soluble B7-H4 (sB7-H4) in autoimmune diseases is unclear. In our study, we developed two novel mouse anti-human B7-H4 monoclonal antibodies (mAbs) (clones 8D4 and 7E1) with utilities for flow cytometry, immunoblotting and immunofluorescence. We characterized 7E1 as a functional antibody with antagonistic activity, which could promote T cell proliferation and regulate cytokine production. Furthermore, based on the different epitope specificities, we established a novel enzyme-linked immunosorbent assay (ELISA) which could detect sB7-H4 sensitively and specifically. Using this ELISA kit, sB7-H4 was observed in a high proportion of autoimmune diseases patients. We found that the levels of sB7-H4 were significantly higher in patients with systemic lupus erythematosus (SLE), type I diabetes (T1D) and Graves' disease (GD). Together, sB7-H4 in human serum is regarded not only as a regulator of T cell activation but may also be a diagnostic marker of autoimmune diseases.

Immune evasion in renal cell carcinoma: biology, clinical translation, future directions

Targeted therapies and immune checkpoint inhibitors have advanced the treatment landscape of Renal Cell Carcinoma (RCC) over the last decade. While checkpoint inhibitors have demonstrated survival benefit and are currently approved in the front-line and second-line settings, primary and secondary resistance is common. A comprehensive understanding of the mechanisms of immune evasion in RCC is therefore critical to the development of effective combination treatment strategies. This article reviews the current understanding of the different, yet coordinated, mechanisms adopted by RCC cells to evade immune killing; summarizes various aspects of clinical translation thus far, including the currently registered RCC clinical trials exploring agents in combination with checkpoint inhibitors; and provides perspectives on the current landscape and future directions for the field.

Overexpression of B7-H4 promotes renal cell carcinoma progression by recruiting tumor-associated neutrophils via upregulation of CXCL8

The immune checkpoint molecule B7 family member H4 (B7-H4) plays a similar role to programmed death-ligand 1 in tumor immune evasion by regulating T-cell-mediated immune responses. However, besides the role in T-cell immunity, B7-H4 also affects tumor cell biology by promoting tumor cell proliferation, metastasis and angiogenesis. In order to explore the effect of B7-H4 on tumor cell biology, it is necessary to investigate the gene expression profile when B7-H4 is overexpressed. In the present study, 786-O cells were transfected to stably express B7-H4. A microarray technique was subsequently used to screen B7-H4-related differentially expressed genes (DEGs) in B7-H4/786-O cells compared with negative control (NC)/786-O cells. The protein expression of the upregulated DEGs, including non-metastatic cells 5, NME/NM23 family member 5 (NME5), membrane metalloendopeptidase (MME), vascular non-inflammatory molecule 1 (VNN1), matrix metalloproteinase (MMP) 7, tumor necrosis factor, C-X-C motif chemokine ligand (CXCL) 8, CXCL1 and C-C motif chemokine ligand (CCL) 2, was investigated using western blotting. Kidney renal papillary cell carcinoma mRNA-sequencing data obtained from The Cancer Genome Atlas revealed that chemokines, including CXCL1/2/3, CXCL8, MMP7 and CCL20, were positively correlated with B7-H4 gene expression. Furthermore, 59 clinical renal cell carcinoma tissues were collected and analyzed by immunohistochemical staining. The results revealed the positive correlation of B7-H4 with CCL20 and CXCL8, and validated the DEGs identified in tumor cell lines. 786-O transfectants were inoculated into non-obese diabetic/severe combined immunodeficiency mice, and tumor growth was investigated. B7-H4 overexpression promoted tumor growth and administration of anti-CXCL8 antibody reversed this effect. Furthermore, B7-H4 overexpression increased the number of tumor-infiltrating neutrophils while inhibition of CXCL8 abrogated this effect. These data indicated that recruitment of neutrophils in the tumor microenvironment by CXCL8 serves an important role in the tumor promotion effect of B7-H4. The present study revealed a novel mechanism of B7-H4 in tumor promotion in addition to T cell inhibition.

Combined detection of CA19-9 and B7-H4 in the diagnosis and prognosis of pancreatic cancer

BACKGROUND

There were no specific indicators for the early detection of pancreatic cancer.

OBJECTIVE

To analyze the diagnostic and prognostic value of CA19-9 plus B7-H4 detection in preoperative serum or surgical tissues of patients with pancreatic cancer.

METHODS

One hundred and eighty-eight patients with pancreatic cancer and 25 controls were recruited. Their preoperative serum CA19-9 level was detected chemiluminescently, and B7-H4 expression in pancreatic cancer tissues was assessed immunohistochemically. The diagnostic and prognostic utility of detecting CA19-9, B7-H4 and their combination was evaluated.

RESULTS

CA19-9 and B7-H4 levels were significantly upregulated in patients with pancreatic cancer compared with those in controls. The diagnostic value of combined CA19-9 plus B7-H4 detection was markedly better than that achieved from their separate detection analyzed with receiver operating characteristic curve. Sensitivity and specificity of the combined detection in the pancreatic cancer group was significantly increased compared with single detection. B7-H4 detection showed better prognostic value than detection of CA19-9. However, CA19-9 had high sensitivity and low specificity, while B7-H4 showed the opposite. The sensitivity of the combined prognosis was not significantly different to B7-H4 alone.

CONCLUSION

The combined detection of CA19-9 and B7-H4 could become a new method for the clinical diagnosis and prognosis of pancreatic cancer.

Immune checkpoint: The novel target for antitumor therapy

Inhibitory checkpoint molecules include programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), cytotoxic T lymphocyte antigen-4 (CTLA-4), human endogenous retrovirus-H Long terminal repeat-associating 2 (HHLA2), B7 homolog 4 protein (B7-H4), T cell membrane protein-3 (TIM-3) and Lymphocyte-activation gene 3 (LAG-3), which are up-regulated during tumorigenesis. These pathways are essential to down-regulate the immune system by blocking the activation of T cells. In recent years, immune checkpoint blockers (ICBs) against PD-1, PD-L1, CTLA-4 or TIM-3 has made remarkable progress in the clinical application, revolutionizing the treatment of malignant tumors and improving patients' overall survival. However, the efficacy of ICBs in some patients does not seem to be good enough, and more immune-related adverse events (irAEs) will inevitably occur. Therefore, biomarkers research provides practical guidance for clinicians to identify patients who are most likely to benefit from or exhibit resistance to particular types of immune checkpoint therapy. There are two points in general. On the one hand, given the spatial and temporal differential expression of immune checkpoint molecules during immunosuppression process, it is essential to understand their mechanisms to design the most effective individualized therapy. On the other hand, due to the lack of potent immune checkpoints, it is necessary to combine them with novel biomarkers (such as exosomes and ctDNA) and other anticancer modalities (such as chemotherapy and radiotherapy).

B7-H4, a promising target for immunotherapy

The coinhibitory molecule B7-H4, an important member of the B7 family, is abnormally expressed in tumors, inflammation and autoimmune diseases. B7-H4 negatively regulates T cell immune response and promotes immune escape by inhibiting the proliferation, cytokine secretion, and cell cycle of T cells. Moreover, B7-H4 plays an extremely important role in tumorigenesis and tumor development including cell proliferation, invasion, metastasis, anti-apoptosis, etc. In addition, B7-H4 has the other biological functions, such as protection against type 1 diabetes (T1D) and islet cell transplantation. Therefore, B7-H4 has been identified as a novel marker or a therapeutic target for the treatment of tumors, inflammation, autoimmune diseases, and organ transplantation. Here, we summarized the expression profiles, physiological and pathological functions, and regulatory mechanisms of B7-H4, the signaling pathways involved, as well as B7-H4-based immunotherapy.

Current Perspectives in Cancer Immunotherapy

Different immunotherapeutic approaches have proved to be of significant clinical value to many patients with different types of advanced cancer. However, we need more precise immunotherapies and predictive biomarkers to increase the successful response rates. The advent of next generation sequencing technologies and their applications in immuno-oncology has helped us tremendously towards this aim. We are now moving towards the realization of personalized medicine, thus, significantly increasing our expectations for a more successful management of the disease. Here, we discuss the current immunotherapeutic approaches against cancer, including immune checkpoint blockade with an emphasis on anti-PD-L1 and anti-CTLA-4 monoclonal antibodies. We also analyze a growing list of other co-inhibitory and co-stimulatory markers and emphasize the mechanism of action of the principal pathway for each of these, as well as on drugs that either have been FDA-approved or are under clinical investigation. We further discuss recent advances in other immunotherapies, including cytokine therapy, adoptive cell transfer therapy and therapeutic vaccines. We finally discuss the modulation of gut microbiota composition and response to immunotherapy, as well as how tumor-intrinsic factors and immunological processes influence the mutational and epigenetic landscape of progressing tumors and response to immunotherapy but also how immunotherapeutic intervention influences the landscape of cancer neoepitopes and tumor immunoediting.

Correction: Serum soluble B7-H4 is a prognostic marker for patients with non-metastatic clear cell renal cell carcinoma

[This corrects the article DOI: 10.1371/journal.pone.0199719.].