Molecular Pathways: Evaluating the Potential for B7-H4 as an Immunoregulatory Target

Palmitoylation prevents B7-H4 lysosomal degradation sustaining tumor immune evasion

B7-H4 functions as an immune checkpoint in the tumor microenvironment (TME). However, the post-translational modification (PTM) of B7-H4 and its translational potential in cancer remains incompletely understood. We find that ZDHHC3, a zinc finger DHHC-type palmitoyltransferase, palmitoylates B7-H4 at Cys130 in breast cancer cells, preventing its lysosomal degradation and sustaining B7-H4-mediated immunosuppression. Knockdown of ZDHHC3 in tumors results in robust anti-tumor immunity and reduces tumor progression in murine models. Moreover, abemaciclib, a CDK4/6 inhibitor, primes lysosome activation and promotes lysosomal degradation of B7-H4 independently of the tumor cell cycle. Treatment with abemaciclib results in T cell activation and mitigates B7-H4-mediated immune suppression via inducing B7-H4 degradation in preclinical tumor models. Thus, B7-H4 palmitoylation is an important PTM controlling B7-H4 protein stability and abemaciclib may be repurposed to promote B7-H4 degradation, thereby treating patients with B7-H4 expressing tumors.

Identification of a Cancer Stem Cell-Related Gene Signature in Hepatocellular Carcinoma Based on Single-Cell RNA-Seq and Bulk RNA-Seq Analysis

Cancer stem cells (CSCs) are a heterogeneous group of tumor cells that play a significant role in tumorigenesis, therapeutic resistance, and recurrence in liver hepatocellular carcinoma (LIHC). This study combines clinical data sets from The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC) with bulk RNA sequencing data. This study also features the GSE156625 single-cell RNA sequencing (scRNA) data set from the GEO to explore the prognostic significance of CSC biomarkers (BCSCs) in LIHC. In this research, we introduce a developed prognostic risk model that relies on nine specific BCSCs, including ADM, CCL5, CD274, DLGAP5, HOXD9, IGF1, S100A9, SOCS2, and TNFRSF11B. It was found that high-risk patients experience shorter overall survival rates when compared to low-risk patients. Additionally, the study characterized the composition of immune cells within the tumor microenvironment (TME) and revealed significant variations in gene-expression levels and mutation rates between different risk groups. The model suggests that liver cancer progression might be driven by immune evasion independent of PD-L1 and highlights the potential of the low-risk BCSC group being sensitive to various treatments. Our findings offer a promising foundation for personalized LIHC therapy and highlight the need for further experimental validation of the roles of these CSCs in disease progression.

Harnessing 2D and 3D human endometrial cell culture models to investigate SARS-CoV-2 infection in early pregnancy

Vertical transmission of SARS-CoV-2 during human pregnancy remains highly controversial as most studies have focused on the third trimester or the peripartum period. Given the lack of early trimester data, determining the prevalence of vertical transmission during early pregnancy and assessing the potential risks for fetal morbidity and mortality pose a challenge. Therefore, we analysed the impact of SARS-CoV-2 infection on an endometrial 3D spheroid model system. The 3D spheroids are capable of decidualization and express angiotensin-converting enzyme 2 (ACE2) as well as transmembrane protease serine 2 (TMPRSS2), rendering them susceptible to SARS-CoV-2 infection. Employing this 3D cell model, we identified that SARS-CoV-2 can infect both non-decidualized and decidualized endometrial spheroids. Infection significantly increased the chemokine Monocyte chemoattractant protein-1 (MCP-1) compared to non-infected spheroids. Decidualized spheroids exhibited upregulated Interleukin (IL)-8 levels. Furthermore, RNA sequencing revealed dysregulation of several genes involved in tissue-specific immune response, Fc receptor signalling, angiotensin-activated signalling and actin function. Gene expression changes varied between SARS-CoV-2 infected non-decidualized and decidualized spheroids and genes associated with the innate immune system (CD38, LCN2 and NR4A3) were dysregulated as a potential mechanism for immune evasion of SARS-CoV-2. Altogether, our study demonstrates that endometrial spheroids are a useful model to examine the clinical implications of SARS-CoV-2 vertical transmission, warranting further investigations.

sB7-H4 is a diagnostic biomarker in epithelial ovarian cancer and correlates to platinum resistance

Ovarian cancer (OC), with its high mortality rate among gynecological cancers, is often diagnosed late due to the lack of early diagnostic symptoms and biomarkers. The tumor immune microenvironment has become a focal point in cancer diagnostic and therapeutic research. Among these, B7-H4, a checkpoint protein, plays a crucial role in immune regulation and tumor suppression, contributing to immune evasion within the tumor microenvironment. This study aims to identify the concentration of soluble B7-H4(sB7-H4) in the plasma of patients with OC and to evaluate its clinical significance. Through a comprehensive analysis involving enzyme-linked immunosorbent assay, immunohistochemistry, and multicolor immunofluorescence, we quantified sB7-H4 levels in patient plasma and ascites, correlating these findings with tissue expression and clinical outcomes. Results indicated a strong association between high sB7-H4 levels and advanced disease, surgical outcomes, lymphatic metastasis, and platinum resistance. When compared with traditional biomarkers CA125 and HE4, sB7-H4, especially in conjunction with these markers, enhances the diagnostic accuracy for epithelial ovarian cancer (EOC), offering insights into disease progression and therapeutic efficacy. This comprehensive analysis suggests that sB7-H4 is a promising biomarker for EOC, providing valuable insights into diagnosis, stage differentiation, treatment effectiveness, and prognosis.

Predictive value of ZFHX4 mutation for the efficacy of immune checkpoint inhibitors in non-small cell lung cancer and melanoma

Studies have shown that the Zinc finger homeobox 4 (ZFHX4) might be a factor in the prognosis of malignancies. However, little is known about the association between the ZFHX4 mutation and the effectiveness of immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) and melanoma. Three public ICIs-treated NSCLC cohorts were divided into discovery cohort (n=75) and validation cohort (n=62), which were used to evaluate the relationship between ZFHX4 mutation and ICIs effectiveness in NSCLC. Seven ICIs-treated melanoma cohorts (n = 418) were used to analyze the relationship between ZFHX4 mutation and immunotherapy efficacy in melanoma. NSCLC and skin cutaneous melanoma (SKCM) cohorts from The Cancer Genome Atlas (TCGA) were used to investigate underlying mechanism. Patients with ZFHX4 mutant-type (ZFHX4-Mut) showed a superior objective response rate (ORR) (P < 0.01) and longer progression-free survival (PFS) (P < 0.05) than patients with ZFHX4 wild-type (ZFHX4-WT) in NSCLC cohorts. In the melanoma cohorts, patients carrying ZFHX4-Mut had a higher ORR (P = 0.042) and longer overall survival (OS) (P = 0.011). Besides, patients with NSCLC and melanoma harboring ZFHX4-Mut had a higher tumor mutation burden (TMB) (P<0.001) and tumor neoantigen burden (TNB) (P<0.001) than those harboring ZFHX4-WT. ZFHX4 mutation was associated with higher levels of plasma B cells, activated CD4+ memory T cells, and CD8+ T cells. Seven DNA damage repair pathways were significantly enriched in the ZFHX4-Mut group. ZFHX4 mutation could serve as a predicter for the efficacy of ICIs therapy in NSCLC and melanoma.

Pancreatic Epithelial IL17/IL17RA Signaling Drives B7-H4 Expression to Promote Tumorigenesis

IL17 is required for the initiation and progression of pancreatic cancer, particularly in the context of inflammation, as previously shown by genetic and pharmacological approaches. However, the cellular compartment and downstream molecular mediators of IL17-mediated pancreatic tumorigenesis have not been fully identified. This study examined the cellular compartment required by generating transgenic animals with IL17 receptor A (IL17RA), which was genetically deleted from either the pancreatic epithelial compartment or the hematopoietic compartment via generation of IL17RA-deficient (IL17-RA-/-) bone marrow chimeras, in the context of embryonically activated or inducible Kras. Deletion of IL17RA from the pancreatic epithelial compartment, but not from hematopoietic compartment, resulted in delayed initiation and progression of premalignant lesions and increased infiltration of CD8+ cytotoxic T cells to the tumor microenvironment. Absence of IL17RA in the pancreatic compartment affected transcriptional profiles of epithelial cells, modulating stemness, and immunological pathways. B7-H4, a known inhibitor of T-cell activation encoded by the gene Vtcn1, was the checkpoint molecule most upregulated via IL17 early during pancreatic tumorigenesis, and its genetic deletion delayed the development of pancreatic premalignant lesions and reduced immunosuppression. Thus, our data reveal that pancreatic epithelial IL17RA promotes pancreatic tumorigenesis by reprogramming the immune pancreatic landscape, which is partially orchestrated by regulation of B7-H4. Our findings provide the foundation of the mechanisms triggered by IL17 to mediate pancreatic tumorigenesis and reveal the avenues for early pancreatic cancer immune interception. See related Spotlight by Lee and Pasca di Magliano, p. 1130.

Prospects and challenges of CAR-T in the treatment of ovarian cancer

Ovarian cancer ranks as the seventh most prevalent cancer among women and is considered the most lethal gynecological malignancy on a global scale. The absence of reliable screening techniques, coupled with the insidious onset of nonspecific symptoms, often results in a delayed diagnosis, typically at an advanced stage characterized by peritoneal involvement. Management of advanced tumors typically involves a combination of chemotherapy and cytoreductive surgery. However, the therapeutic arsenal for ovarian cancer patients remains limited, highlighting the unmet need for precise, targeted, and sustained-release pharmacological agents. Genetically engineered T cells expressing chimeric antigen receptors (CARs) represent a promising novel therapeutic modality that selectively targets specific antigens, demonstrating robust and enduring antitumor responses in numerous patients. CAR T cell therapy has exhibited notable efficacy in hematological malignancies and is currently under investigation for its potential in treating various solid tumors, including ovarian cancer. Currently, numerous researchers are engaged in the development of novel CAR-T cells designed to target ovarian cancer, with subsequent evaluation of these candidate cells in preclinical studies. Given the ability of chimeric antigen receptor (CAR) expressing T cells to elicit potent and long-lasting anti-tumor effects, this therapeutic approach holds significant promise for the treatment of ovarian cancer. This review article examines the utilization of CAR-T cells in the context of ovarian cancer therapy.

Epithelial Expressed B7-H4 Drives Differential Immunotherapy Response in Murine and Human Breast Cancer

Combinations of immune checkpoint inhibitors (ICI, including anti-PD-1/PD-L1) and chemotherapy have been FDA approved for metastatic and early-stage triple-negative breast cancer (TNBC), but most patients do not benefit. B7-H4 is a B7 family ligand with proposed immunosuppressive functions being explored as a cancer immunotherapy target and may be associated with anti-PD-L1 resistance. However, little is known about its regulation and effect on immune cell function in breast cancers. We assessed murine and human breast cancer cells to identify regulation mechanisms of B7-H4 in vitro. We used an immunocompetent anti-PD-L1-sensitive orthotopic mammary cancer model and induced ectopic expression of B7-H4. We assessed therapy response and transcriptional changes at baseline and under treatment with anti-PD-L1. We observed B7-H4 was highly associated with epithelial cell status and transcription factors and found to be regulated by PI3K activity. EMT6 tumors with cell-surface B7-H4 expression were more resistant to immunotherapy. In addition, tumor-infiltrating immune cells had reduced immune activation signaling based on transcriptomic analysis. Paradoxically, in human breast cancer, B7-H4 expression was associated with survival benefit for patients with metastatic TNBC treated with carboplatin plus anti-PD-L1 and was associated with no change in response or survival for patients with early breast cancer receiving chemotherapy plus anti-PD-1. While B7-H4 induces tumor resistance to anti-PD-L1 in murine models, there are alternative mechanisms of signaling and function in human cancers. In addition, the strong correlation of B7-H4 to epithelial cell markers suggests a potential regulatory mechanism of B7-H4 independent of PD-L1.

SIGNIFICANCE

This translational study confirms the association of B7-H4 expression with a cold immune microenvironment in breast cancer and offers preclinical studies demonstrating a potential role for B7-H4 in suppressing response to checkpoint therapy. However, analysis of two clinical trials with checkpoint inhibitors in the early and metastatic settings argue against B7-H4 as being a mechanism of clinical resistance to checkpoints, with clear implications for its candidacy as a therapeutic target.

Targeting intratumoral hypoxia to enhance anti-tumor immunity

Cancers express a large battery of genes by which they establish an immunosuppressive tumor microenvironment. Many of these genes are induced by intratumoral hypoxia through transcriptional activation mediated by hypoxia-inducible factors HIF-1 and HIF-2. This review summarizes several recent reports describing hypoxia-induced mechanisms of immune evasion in sarcoma and breast, colorectal, hepatocellular, prostate and uterine cancer. These studies point to several novel therapeutic approaches to improve anti-tumor immunity and increase responses to immunotherapy.

The loss of B7-H4 expression in breast cancer cells escaping from T cell cytotoxicity contributes to epithelial-to-mesenchymal transition

BACKGROUND

B7 homology 4 (B7-H4), a potential target for cancer therapy, has been demonstrated to inhibit T cell cytotoxicity in the early stages of breast cancer. However, B7-H4 manipulating breast tumor immune microenvironment (TIME) in the tumor progression remains unknown.

METHODS

We engineered T cells with B7-H4-specific chimeric antigen receptors (CARs) and performed a T cell co-culture assay to characterize B7-H4 expression level in breast cancer cells escaping from T cell cytotoxicity. We generated B7-H4 knockout (KO) and overexpression (OE) breast cancer cells to determine the epithelial-to-mesenchymal transition (EMT) and stemness characteristics in vitro and in vivo, including tumor proliferation, migration, metastasis and chemoresistance. The Cancer Genome Atlas breast cancer database was accessed to investigate the correlation between B7-H4 expression levels and EMT characteristics in patients with breast cancer.

RESULTS

Our result found that B7-H4 expression level was significantly reduced in a subset of breast cancer cells that escaped from the cytotoxicity of B7-H4 CAR-T cells. Compared with wild type cells, B7-H4 KO cells prompt EMT and stemness characteristics, including migration, invasion and metastasis, and OE cells vice versa. The increase in H3K27me3 in KO cells confirmed the epigenetic reprogramming of cancer stem cells. The IC50 of doxorubicin or oxaliplatin significantly increased in KO cells, which was in agreement with a decrease in OE cells. Moreover, a trend of downregulated B7-H4 from stage I to stage II breast cancer patients indicates that the low-expressing B7-H4 breast cancer cells escaping from TIME have spread to nearby breast lymph nodes in the cancer progression.

CONCLUSIONS

Our study illuminates the novel role of renouncing B7-H4 in breast cancer cells through immune escape, which contributes to EMT processes and provides new insights for breast cancer treatments.

SGN-B7H4V, an investigational vedotin ADC directed to the immune checkpoint ligand B7-H4, shows promising activity in preclinical models

BACKGROUND

SGN-B7H4V is a novel investigational vedotin antibody-drug conjugate (ADC) comprising a B7-H4-directed human monoclonal antibody conjugated to the cytotoxic payload monomethyl auristatin E (MMAE) via a protease-cleavable maleimidocaproyl valine citrulline (mc-vc) linker. This vedotin linker-payload system has been clinically validated in multiple Food and Drug Administration approved agents including brentuximab vedotin, enfortumab vedotin, and tisotumab vedotin. B7-H4 is an immune checkpoint ligand with elevated expression on a variety of solid tumors, including breast, ovarian, and endometrial tumors, and limited normal tissue expression. SGN-B7H4V is designed to induce direct cytotoxicity against target cells by binding to B7-H4 on the surface of target cells and releasing the cytotoxic payload MMAE upon internalization of the B7-H4/ADC complex.

METHODS

B7-H4 expression was characterized by immunohistochemistry across multiple solid tumor types. The ability of SGN-B7H4V to kill B7-H4-expressing tumor cells in vitro and in vivo in a variety of xenograft tumor models was also evaluated. Finally, the antitumor activity of SGN-B7H4V as monotherapy and in combination with an anti-programmed cell death-1 (PD-1) agent was evaluated using an immunocompetent murine B7-H4-expressing Renca tumor model.

RESULTS

Immunohistochemistry confirmed B7-H4 expression across multiple solid tumors, with the highest prevalence in breast, endometrial, and ovarian tumors. In vitro, SGN-B7H4V killed B7-H4-expressing tumor cells by MMAE-mediated direct cytotoxicity and antibody-mediated effector functions including antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis. In vivo, SGN-B7H4V demonstrated strong antitumor activity in multiple xenograft models of breast and ovarian cancer, including xenograft tumors with heterogeneous B7-H4 expression, consistent with the ability of vedotin ADCs to elicit a bystander effect. In an immunocompetent murine B7-H4-expressing tumor model, SGN-B7H4V drove robust antitumor activity as a monotherapy that was enhanced when combined with an anti-PD-1 agent.

CONCLUSION

The immune checkpoint ligand B7-H4 is a promising molecular target expressed by multiple solid tumors. SGN-B7H4V demonstrates robust antitumor activity in preclinical models through multiple potential mechanisms. Altogether, these preclinical data support the evaluation of SGN-B7H4V as a monotherapy in the ongoing phase 1 study of SGN-B7H4V in advanced solid tumors (NCT05194072) and potential future clinical combinations with immunotherapies.

Spatial Immunoprofiling of Adenoid Cystic Carcinoma Reveals B7-H4 Is a Therapeutic Target for Aggressive Tumors

PURPOSE

Adenoid cystic carcinoma (ACC) is a heterogeneous malignancy, and no effective systemic therapy exists for metastatic disease. We previously described two prognostic ACC molecular subtypes with distinct therapeutic vulnerabilities, ACC-I and ACC-II. In this study, we explored the ACC tumor microenvironment (TME) using RNA-sequencing and spatial biology to identify potential therapeutic targets.

EXPERIMENTAL DESIGN

Tumor samples from 62 ACC patients with available RNA-sequencing data that had been collected as part of previous studies were stained with a panel of 28 validated metal-tagged antibodies. Imaging mass cytometry (IMC) was performed using the Fluidigm Helios CyTOF instrument and analyzed with Visiopharm software. The B7-H4 antibody-drug conjugate AZD8205 was tested in ACC patient-derived xenografts (PDX).

RESULTS

RNA deconvolution revealed that most ACCs are immunologically "cold," with approximately 30% being "hot." ACC-I tumors with a poor prognosis harbored a higher density of immune cells; however, spatial analysis by IMC revealed that ACC-I immune cells were significantly restricted to the stroma, characterizing an immune-excluded TME. ACC-I tumors overexpressed the immune checkpoint B7-H4, and the degree of immune exclusion was directly correlated with B7-H4 expression levels, an independent predictor of poor survival. Two ACC-I/B7-H4-high PDXs obtained 90% complete responses to a single dose of AZD8205, but none were observed with isotype-conjugated payload or in an ACC-II/B7-H4 low PDX.

CONCLUSIONS

Spatial analysis revealed that ACC subtypes have distinct TMEs, with enrichment of ACC-I immune cells that are restricted to the stroma. B7-H4 is highly expressed in poor-prognosis ACC-I subtype and is a potential therapeutic target.

Ethacrynic acid suppresses B7-H4 expression involved in epithelial-mesenchymal transition of lung adenocarcinoma cells via inhibiting STAT3 pathway

Lung cancer is characterized by high incidence and mortality. 90% of cancer deaths are caused by metastases. The epithelial-mesenchymal transition (EMT) process in cancer cells is a prerequisite for the metastatic process. Ethacrynic acid (ECA) is a loop diuretic that inhibits the EMT process in lung cancer cells. EMT has been related to the tumour immunemicroenvironment. However, the effect of ECA on immune checkpoint molecules in the context of cancer has not been fully identified. In the present study, we found that sphingosylphosphorylcholine (SPC) and TGF-β1, awell-known EMT inducer, induced the expression of B7-H4 in lung cancer cells. We also investigated the involvement of B7-H4 in the SPC-induced EMT process. Knockdown of B7-H4 suppressed SPC-induced EMT, while B7-H4 overexpression enhanced EMT of lung cancer cells. ECA inhibited SPC/TGF-β1-induced B7-H4 expression via suppression of STAT3 activation. Moreover, ECA inhibits the colonization of mice lung by tail vein-injected LLC1 cells. ECA-treated mice increased the CD4-positive T cells in lung tumour tissues. In summary, these results suggested that ECA inhibits B7-H4 expression via STAT3 inhibition, leading to SPC/TGF-β1-induced EMT. Therefore, ECA might be an immune oncological drug for B7-H4-positive cancer, especially lung cancer.

The immune checkpoint molecule, VTCN1/B7-H4, guides differentiation and suppresses proinflammatory responses and MHC class I expression in an embryonic stem cell-derived model of human trophoblast

The placenta acts as a protective barrier to pathogens and other harmful substances present in the maternal circulation throughout pregnancy. Disruption of placental development can lead to complications of pregnancy such as preeclampsia, intrauterine growth retardation and preterm birth. In previous work, we have shown that expression of the immune checkpoint regulator, B7-H4/VTCN1, is increased upon differentiation of human embryonic stem cells (hESC) to an in vitro model of primitive trophoblast (TB), that VTCN1/B7-H4 is expressed in first trimester but not term human placenta and that primitive trophoblast may be uniquely susceptible to certain pathogens. Here we report on the role of VTCN1 in trophoblast lineage development and anti-viral responses and the effects of changes in these processes on major histocompatibility complex (MHC) class I expression and peripheral NK cell phenotypes.

Radiotherapy plus CAR-T cell therapy to date: A note for cautions optimism?

Radiotherapy (RT) is a traditional therapeutic regime that focuses on ionizing radiation, however, RT maintains largely palliative due to radioresistance. Factors such as hypoxia, the radiosensitivity of immune cells, and cancer stem cells (CSCs) all come into play in influencing the significant impact of radioresistance in the irradiated tumor microenvironment (TME). Due to the substantial advances in the treatment of malignant tumors, a promising approach is the genetically modified T cells with chimeric antigen receptors (CARs) to eliminate solid tumors. Moreover, CAR-T cells targeting CSC-related markers would eliminate radioresistant solid tumors. But solid tumors that support an immune deserted TME, are described as immunosuppressive and typically fail to respond to CAR-T cell therapy. And RT could overcome these immunosuppressive features; thus, growing evidence supports the combination of RT with CAR-T cell therapy. In this review, we provide a deep insight into the radioresistance mechanisms, advances, and barriers of CAR-T cells in response to solid tumors within TME. Therefore, we focus on how the combination strategy can be used to eliminate these barriers. Finally, we show the challenges of this therapeutic partnership.

A Novel Immune-Related Gene Prognostic Index (IRGPI) in Pancreatic Adenocarcinoma (PAAD) and Its Implications in the Tumor Microenvironment

PURPOSE

Pancreatic adenocarcinoma (PAAD) is one of the most lethal malignancies, with less than 10% of patients surviving more than 5 years. Existing biomarkers for reliable survival rate prediction need to be enhanced. As a result, the objective of this study was to create a novel immune-related gene prognostic index (IRGPI) for estimating overall survival (OS) and to analyze the molecular subtypes based on this index. Materials and procedures: RNA sequencing and clinical data were retrieved from publicly available sources and analyzed using several R software packages. A unique IRGPI and optimum risk model were developed using a machine learning algorithm. The prediction capability of our model was then compared to that of previously proposed models. A correlation study was also conducted between the immunological tumor microenvironment, risk groups, and IRGPI genes. Furthermore, we classified PAAD into different molecular subtypes based on the expression of IRGPI genes and investigated their features in tumor immunology using the K-means clustering technique.

RESULTS

A 12-gene IRGPI (FYN, MET, LRSAM1, PSPN, ERAP2, S100A1, IL20RB, MAP3K14, SEMA6C, PRKCG, CXCL11, and GH1) was established, and verified along with a risk model. OS prediction by our model outperformed previous gene signatures. According to the findings of our correlation studies, different risk groups and IRGPI genes were found to be tightly related to tumor microenvironments, and PAAD could be further subdivided into immunologically distinct molecular subtypes based on the expression of IRGPI genes.

CONCLUSION

The current study constructed and verified a unique IRGPI. Furthermore, our findings revealed a connection between the IRGPI and the immunological microenvironment of tumors. PAAD was differentiated into several molecular subtypes that might react differently to immunotherapy. These findings could provide new insights for precision and translational medicine for more innovative immunotherapy strategies.

The Monocyte, a Maestro in the Tumor Microenvironment (TME) of Breast Cancer

Breast cancer (BC) is well-known for being a leading cause of death worldwide. It is classified molecularly into luminal A, luminal B HER2-, luminal B HER2+, HER2+, and triple-negative breast cancer (TNBC). These subtypes differ in their prognosis; thus, understanding the tumor microenvironment (TME) makes new treatment strategies possible. The TME contains populations that exhibit anti-tumorigenic actions such as tumor-associated eosinophils. Moreover, it contains pro-tumorigenic populations such as tumor-associated neutrophils (TANs), or monocyte-derived populations. The monocyte-derived populations are tumor-associated macrophages (TAMs) and MDSCs. Thus, a monocyte can be considered a maestro within the TME. Moreover, the expansion of monocytes in the TME depends on many factors such as the BC stage, the presence of macrophage colony-stimulating factor (M-CSF), and the presence of some chemoattractants. After expansion, monocytes can differentiate into pro-inflammatory populations such as M1 macrophages or anti-inflammatory populations such as M2 macrophages according to the nature of cytokines present in the TME. Differentiation to TAMs depends on various factors such as the BC subtype, the presence of anti-inflammatory cytokines, and epigenetic factors. Furthermore, TAMs and MDSCs not only have a role in tumor progression but also are key players in metastasis. Thus, understanding the monocytes further can introduce new target therapies.

The role of CPT1A as a biomarker of breast cancer progression: a bioinformatic approach

Breast cancer is the commonest malignancy of women and with its incidence on the rise, the need to identify new targets for treatment is imperative. There is a growing interest in the role of lipid metabolism in cancer. Carnitine palmitoyl-transferase-1 (CPT-1); the rate limiting step in fatty acid oxidation, has been shown to be overexpressed in a range of tumours. There are three isoforms of CPT-1; A, B and C. It is CPT-1A that has been shown to be the predominant isoform which is overexpressed in breast cancer. We performed a bioinformatic analysis using readily available online platforms to establish the prognostic and predictive effects related to CPT-1A expression. These include the KM plotter, the Human Protein Atlas, the cBioPortal, the G2O, the MethSurvand the ROC plotter. A Network analysis was performed using the Oncomine platform and signalling pathways constituting the cancer hallmarks, including immune regulation as utilised by NanoString. The epigenetic pathways were obtained from the EpiFactor website. Spearman correlations (r) to determine the relationship between CPT-1A and the immune response were obtained using the TISIDB portal. Overexpression of CPT-1A largely confers a worse prognosis and CPT-1A progressively recruits a range of pathways as breast cancer progresses. CPT-1A's interactions with cancer pathways is far wider than previously realised and includes associations with epigenetic regulation and immune evasion pathways, as well as wild-type moderate to high penetrant genes involved in hereditary breast cancer. Although CPT-1A genomic alterations are detected in 9% of breast carcinomas, both the alteration and the metagene associated with it, confers a poor prognosis. CPT-1A expression can be utilised as a biomarker of disease progression and as a potential therapeutic target.

Exosomal B7-H4 from irradiated glioblastoma cells contributes to increase FoxP3 expression of differentiating Th1 cells and promotes tumor growth

Background

Glioblastoma (GBM) is the most common and aggressive form of primary brain tumor. Although numerous postoperative therapeutic strategies have already been developed, including radiotherapy, tumors inevitably recur after several years of treatment. The coinhibitory molecule B7–H4 negatively regulates T cell immune responses and promotes immune escape. Exosomes mediate intercellular communication and initiate immune evasion in the tumor microenvironment (TME).

Objective

This study aimed to determine whether B7–H4 is upregulated by radiation and loaded into exosomes, thus contributing to immunosuppression and enhancing tumor growth.

Methods

Iodixanol density-gradient centrifugation and flow cytometry were used to verify exosomal B7–H4. Naïve T cells were differentiated into Th1 cells, with or without exosomes. T cell-secreted cytokines and markers of T cell subsets were measured. Mechanistically, the roles of B7–H4, and ALIX in GBM were analyzed using databases and tissue samples. Co‐immunoprecipitation, and pull-down assays were used to tested the direct interactions between ATM and ALIX or STAT3. In vitro ATM kinase assays, western blotting, and site-directed mutation were used to assess ATM-mediated STAT3 phosphorylation. Finally, the contribution of exosomal B7–H4 to immunosuppression and tumor growth was investigated in vivo.

Results

Exosomes from irradiated GBM cells decreased the anti-tumor immune response of T cell in vitro and in vivo via delivered B7–H4. Mechanistically, irradiation promoted exosome biogenesis by increasing the ATM-ALIX interaction. Furthermore, the ATM-phosphorylated STAT3 was found to directly binds to the B7–H4 promoter to increase its expression. Finally, the radiation-induced increase in exosomal B7–H4 induced FoxP3 expression during Th1 cell differentiation via the activated STAT1 pathway. In vivo, exosomal B7–H4 decreased the radiation sensitivity of GBM cells, and reduced the survival of GBM mice model.

Conclusion

This study showed that radiation-enhanced exosomal B7–H4 promoted immunosuppression and tumor growth, hence defining a direct link between irradiation and anti-tumor immune responses. Our results suggest that co-administration of radiotherapy with anti-B7-H4 therapy could improve local tumor control and identify exosomal B7–H4 as a potential tumor biomarker.

Diagnosis Biomarkers of Cholangiocarcinoma in Human Bile: An Evidence-Based Study

Simple Summary

A liquid biopsy has the characteristics of low trauma and easy acquisition in the diagnosis of cholangiocarcinoma. Many researchers try to find diagnostic or prognostic biomarkers of CCA through blood, urine, bile and other body fluids. Due to the close proximity of bile to the lesion and the stable nature, bile gradually comes into people’s view. The evaluation of human bile diagnostic biomarkers is not only to the benefit of screening more suitable clinical markers but also of exploring the pathological changes of the disease.

Abstract

Cholangiocarcinoma (CCA) is a multifactorial malignant tumor of the biliary tract, and the incidence of CCA is increasing in recent years. At present, the diagnosis of CCA mainly depends on imaging and invasive examination, with limited specificity and sensitivity and late detection. The early diagnosis of CCA always faces the dilemma of lacking specific diagnostic biomarkers. Non-invasive methods to assess the degree of CAA have been developed throughout the last decades. Among the many specimens looking for CCA biomarkers, bile has gotten a lot of attention lately. This paper mainly summarizes the recent developments in the current research on the diagnostic biomarkers for CCA in human bile at the levels of the gene, protein, metabolite, extracellular vesicles and volatile organic compounds.

Aryl Hydrocarbon Receptor Directly Regulates VTCN1 Gene Expression in MCF-7 Cells

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the toxicity of dioxins and polycyclic aromatic hydrocarbons. Recent studies have suggested that AhR is involved in cancer immunity. In the present study, we examined whether AhR regulates the expression of immune checkpoint genes in breast cancer cells. We discovered that the mRNA expression of V-set domain containing T cell activation inhibitor 1 (VTCN1) that negatively regulates T cell immunity was upregulated by AhR agonists in breast cancer cell lines, MCF-7 and T47D. Furthermore, AhR knockout or knockdown experiments clearly demonstrated that upregulation of VTCN1 gene expression by 3-methylcholanthrene was AhR dependent. Luciferase reporter and chromatin immunoprecipitation assays revealed that this upregulation of VTCN1 gene expression was induced by the recruitment of AhR to the AhR responsive element in the VTCN1 gene promoter in MCF-7 cells. Taken together, AhR directly regulates VTCN1 gene expression in MCF-7 cells.

Clinical significance and correlation of PD-L1, B7-H3, B7-H4, and TILs in pancreatic cancer

BACKGROUND

B7 molecules play significant roles in regulating tumor immunity, but their expression patterns and immuno-biological correlations in pancreatic cancer (PaCa) have not been fully discussed.

METHODS

RNA-sequencing data of B7 molecules of PaCa samples in the Cancer Genome Atlas (TCGA) dataset was downloaded from the UCSC Xena to assess the expression, correlation, and mutation of the B7 family in PaCa. Next, two PaCa tissue microarrays (TMAs, Cat. HPanA150CS02 and HPanA120Su02) were obtained from Outdo BioTech (Shanghai, China). To detect the expression levels of PD-L1, B7-H3 and B7-H4, immunohistochemistry (IHC) staining was performed on these TMAs.

RESULTS

Most B7 molecules, including B7-1, B7-2, PD-L1, B7-DC, B7-H2, and B7-H5 exhibited similar expression patterns, but B7-H3, B7-H4, B7-H6, and B7-H7 showed outlier expression patterns compared with other B7 molecules. Besides, B7 molecules were genetically stable and exhibited low alteration frequency. IHC staining indicated PD-L1, B7-H3, and B7-H4 were up-regulated in PaCa tissues and showed uncorrelated expression patterns. Furthermore, high expression of PD-L1 and B7-H3 indicated poor-differentiated grades in PaCa. PD-L1 was positively, but B7-H4 was negatively correlated with CD8+ TILs infiltration in PaCa. Moreover, combined PD-L1 and B7-H4 expression was a novel subtyping strategy in PaCa, namely patients with both high PD-L1 and B7-H4 expression exhibited decreased CD8+ TILs infiltration in tumor tissues.

CONCLUSION

Overall, we systemically analyzed the expression patterns of B7 molecules and proposed a novel subtyping strategy in PaCa. Patients with both high PD-L1 and B7-H4 expression exhibited the immuno-cold phenotype, which may be not suitable for immunotherapy.

Upregulation of B7-H4 Is Involved in and Related to the Severity of Acute Pancreatitis

The expression and clinical significance of co-stimulator B7-H4 in acute pancreatitis (AP) is still unclear. In vitro study showed that the expression of soluble B7-H4 (sB7-H4) and proportions of membrane B7-H4-positive CD14⁺ cells in the peripheral blood mononuclear cells were upregulated in response to stimulation with plasma from AP patients, lipopolysaccharides, or tumor necrosis factor α (TNF-α). sB7-H4 in the plasma of AP patients were positively correlated with interleukin (IL)-6, IL-10, IL-17A, TNF-α, and interferon-γ The areas under the curves (AUCs) of receiver operating characteristic (ROC) curves of plasma sB7-H4 to distinguish the AP patients from healthy donors, the mild AP (MAP) from the moderately severe acute pancreatitis (MSAP)+severe acute pancreatitis (SAP) or the SAP from the MAP+MSAP were 0.78 (P < 0.001) or 0.773 (P < 0.001) or 0.764 (P < 0.001). sB7-H4 in the plasma of patients were positively correlated with the RANSON scores, Bedside Index of Severity of Acute Pancreatitis scores, Marshall scores, and Acute Physiology And Chronic Health Evaluation II scores; and the AUCs of ROC curves of plasma sB7-H4 in the prediction of local complications was 0.726 (P = 0.001). In conclusion, the co-stimulator B7-H4 is involved in the immune response in AP.

Expression of the Costimulatory Molecule B7-H4 in the Decidua and Placental Tissues in Patients with Placental Abruption

B7 homolog 4 protein (B7-H4), a member of the B7 family, is a immunomodulatory membrane protein. The aim of the study was to evaluate the expression of this protein in the decidua and placental tissues in case of placental abruption (PA) compared to cases of retained placental tissue (RPT) and controls. Tissue samples were obtained from 47 patients with PA, 60 patients with RPT, and 41 healthy controls. The samples were stained for B7-H4 expression, analyzed by an expert pathologist, and a semi-quantitative scale was applied. A statistical analysis revealed that the expression of B7-H4 was significantly higher in the decidua in PA samples compared to samples from patients with RPT (p-value < 0.001) and healthy controls (p-value < 0.001). The expression of B7-H4 in the placental chorionic villus was significantly higher in PA samples in relation to samples from healthy controls (p-value < 0.001) but not in relation to RPT samples (p-value = 0.0853). This finding suggests that B7-H4 might play an important role in mechanisms restoring reproductive tract homeostasis. Further research is necessary in regard to the role of B7-H4 in PA.

Current Status and Future Directions of Immunotherapies in Soft Tissue Sarcomas

Immunotherapy in soft tissue sarcoma (STS) has experienced a surge of interest in the past decade, contributing to an expanding number of therapeutic options for this extremely heterogenous group of rare malignancies. Immune checkpoint inhibitors (CPIs) targeting the PD-1 and CTLA-4 axes have demonstrated promising responses in a select number of STS subtypes, including rarer subtypes, such as alveolar soft part sarcoma, SWI/SNF-deficient sarcomas, clear cell sarcoma, and angiosarcoma. Multiple pan-subtype sarcoma trials have facilitated the study of possible predictive biomarkers of the CPI response. It has also become apparent that certain therapies, when combined with CPIs, can enhance response rates, although the specific mechanisms of this possible synergy remain unconfirmed in STS. In addition to CPIs, several other immune targeting agents, including anti-tumour-associated macrophage and antigen-directed therapies, are now under assessment in STS with promising efficacy in some subtypes. In this article, we review the state of the art in immunotherapy in STS, highlighting the pre-clinical and clinical data available for this promising therapeutic strategy.

The immunogenomic landscape of resected intrahepatic cholangiocarcinoma

BACKGROUND AND AIMS

Cholangiocarcinoma (CCA) is a deadly and highly therapy-refractory cancer of the bile ducts, with early results from immune checkpoint blockade trials showing limited responses. Whereas recent molecular assessments have made bulk characterizations of immune profiles and their genomic correlates, spatial assessments may reveal actionable insights.

APPROACH AND RESULTS

Here, we have integrated immune checkpoint-directed immunohistochemistry with next-generation sequencing of resected intrahepatic CCA samples from 96 patients. We found that both T-cell and immune checkpoint markers are enriched at the tumor margins compared to the tumor center. Using two approaches, we identify high programmed cell death protein 1 or lymphocyte-activation gene 3 and low CD3/CD4/inducible T-cell costimulator specifically in the tumor center as associated with poor survival. Moreover, loss-of-function BRCA1-associated protein-1 mutations are associated with and cause elevated expression of the immunosuppressive checkpoint marker, B7 homolog 4.

CONCLUSIONS

This study provides a foundation on which to rationally improve and tailor immunotherapy approaches for this difficult-to-treat disease.

The B7H4-PDL1 classifier stratifies immuno-phenotype in cervical cancer

BACKGROUND

It has been revealed that B7H4 is negatively correlated with PDL1 and identifies immuno-cold tumors in glioma. However, the application of the B7H4-PDL1 classifier in cancers has not been well testified.

METHODS

A pan-cancer analysis was conducted to evaluate the immunological role of B7H4 using the RNA-sequencing data downloaded from the Cancer Genome Atlas (TCGA). Immunohistochemistry (IHC) and multiplexed quantitative immunofluorescence (QIF) were performed to validate the primary results revealed by bioinformatics analysis.

RESULTS

The pan-cancer analysis revealed that B7H4 was negatively correlated with PDL1 expression and immune cell infiltration in CeCa. In addition, patients with high B7H4 exhibited the shortest overall survival (OS) and relapse-free survival (RFS) while those with high PDL1 exhibited a better prognosis. Multiplexed QIF showed that B7H4 was mutually exclusive with PDL1 expression and the B7H4-high group exhibited the lowest CD8 + T cell infiltration. Besides, B7H4-high predicted highly proliferative subtypes, which expressed the highest Ki67 antigen. Moreover, B7H4-high also indicated a lower response to multiple therapies.

CONCLUSIONS

Totally, the B7H4-PDL1 classifier identifies the immunogenicity and predicts proliferative subtypes and limited therapeutic options in CeCa, which may be a convenient and feasible biomarker in clinical practice.

Impact of immune cells on the hallmarks of cancer: A literature review

Tumor-infiltrating immune cells (TIICs) are critical players in the tumor microenvironment, modulating cancer cell functions. TIICs are highly heterogenic and plastic and may either suppress cancers or provide support for tumor growth. A wide range of studies have shed light on how tumor-associated macrophages, dendritic cells, neutrophils, mast cells, natural killer cells and lymphocytes contribute for the establishment of several hallmarks of cancer and became the basis for successful immunotherapies. Many of those TIICs play pivotal roles in several hallmarks of cancer. This review contributes to elucidate the multifaceted roles of immune cells in cancer development, highlighting molecular components that constitute promising therapeutic targets. Additional studies are needed to clarify the relation between TIICs and hallmarks such as enabling replicative immortality, evading growth suppressors, sustaining proliferative signaling, resisting cell death and genome instability and mutation, to further explore their therapeutic potential and improve the outcomes of cancer patients.

Elevated expression of B7 homolog 4 is associated with disease progression in upper urinary tract urothelial carcinoma

Background

B7 homolog 4 (B7-H4) is a negative regulator of immune responses, but its immunoregulatory role in the tumor microenvironment of upper urinary tract urothelial carcinoma (UTUC) remains unclear.

Methods

We measured the immunohistochemical expression of B7-H4, CD8 and T cell intracellular antigen 1 (TIA-1), a marker of activated CD8, in 133 patients with UTUC who underwent nephroureterectomy. We also studied the relationship between B7-H4, CD8 and TIA-1 expression and clinicopathological characteristics.

Results

B7-H4 was mainly expressed on the surface in tumor cells, while CD8 and TIA-1 were often expressed in tumor-infiltrating lymphocytes. Elevated expression of B7-H4 in tumor cells was associated with a poorer histological grade, higher pT stage, regional lymph node metastasis, lymphovascular invasion, poorer response of recurrent metastatic lesions to systemic chemotherapy and shorter overall survival. Expression of CD-8 or TIA-1 alone did not correlate directly with clinicopathological characteristics, but among the patients with higher B7-H4 expression in the primary tumors, those with higher CD8 or TIA-1 expression had a better response to systemic chemotherapy, and longer survival, than these with lower CD8 or TIA-1 expression. Cox multivariate regression analysis revealed that higher expression of B7-H4 was associated with shorter overall survival.

Conclusions

These findings suggest that B7-H4 expression in the tumor microenvironment influences the progression of UTUC through cancer immunity and metabolic activity. Tumor cell-associated B7-H4 might be a potential target for cancer immunotherapies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-03011-5.

Development of a novel anti-B7-H4 antibody enhances anti-tumor immune response of human T cells

BACKGROUND

B7-H4 is a member of the B7 superfamily that is expressed on the surface of tumors and exhibits limited expression on normal tissue. B7-H4 negatively regulates tumor immunity by interacting with the B7-H4 receptor, which is expressed by activated CD8 + T cells. Hence, we sought to generate an immunomodulatory antibody that targets B7-H4 and blocks the immunosuppressive activity of B7-H4.

METHODS

Anti-B7-H4 antibodies were generated using the hybridoma technique and screened by a binding assay based on B7-H4-expressing tumor cells. The B7-H4 antagonistic antibodies were further screened based on their checkpoint blockade activity using a SEB-stimulated peripheral blood mononuclear cell (PBMC) assay, which comprised B7-H4-expressing antigen presenting cells (APCs) and activated T cells. To assess the immunomodulatory activity of anti-B7-H4 antibodies, activated human CD8+ T cells were cultured in B7-H4 protein-coated plates, and the production of IL-2 and the proliferation rate of CD8+ T cells were measured. In addition, we evaluated the ADCC effect of anti-B7-H4 antibodies against tumor cell lines. The in vivo antitumor efficacy of the anti-B7-H4 antibody was also evaluated in human T cell-engrafted NOG mice.

RESULTS

A panel of anti-B7-H4 antibodies was generated. The top 23 antibodies were screened to identify antibodies that disabled B7-H4-mediated inhibition. Antibody 17 exhibited the greatest induction of the production of IL-2 and IFN-gamma in SEB-stimulated PBMCs. Antibody 17 was constructed as a chimeric antibody (CH17) with a human IgG1 constant domain. CH17 showed high affinity for human B7-H4 and fully cross-reacted with cynomolgus B7-H4. Additionally, CH17 mediated potent antibody-dependent cell cytotoxicity (ADCC) against different B7-H4-positive tumor cell lines. More importantly, CH17 relieved B7-H4-mediated T cell suppression by enhancing IL2 production and promoting T cell proliferation. In an MDA-MB-468-bearing mouse model in which human pan-T cells were engrafted, CH17 delayed tumor growth by engaging T cells and exerted a synergistic effect in combination with an anti-human PD-1 antibody.

CONCLUSIONS

We successfully generated an immunomodulatory antibody targeting B7-H4 that possesses both T cell immune checkpoint inhibitory activity and ADCC activity in B7-H4-positive tumors. B7-H4-targeting antibodies might represent a promising immunotherapy for B7-H4-expressing tumors.

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.

Comparative Analysis and in vitro Experiments of Signatures and Prognostic Value of Immune Checkpoint Genes in Colorectal Cancer

Purpose

Immune checkpoints, as pivotal regulators of immune escape in cancer, can motivate the emergence of immune checkpoint inhibitors (ICIs). The aim of this study is to identify the expression of the immune checkpoint genes (ICGs) in colorectal cancer (CRC) and to relate their individual as well as combined expression to prognosis and therapeutic effectiveness in CRC.

Methods

RNA expression of 47 ICGs and clinical information of CRC patients were collected from two public databases to elucidate the expression levels and prognostic values of these ICGs in CRC. Then, the Shapiro–Wilk normality test was used to determine the normality of variables. Overall survival (OS) rates of each subset were found by Kaplan–Meier method, and the statistical significance was determined by the Log rank test (p < 0.05).

Results

The expression of 13 and 9 ICGs was significantly associated with CRC prognosis in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) cohorts. A series of ICGs was found to be significantly associated with TMB, neoantigens and MMR in CRC indicating that the combination of immunotherapy treatment biomarkers and ICGs may achieve accurate prognostic stratification of CRC, and potentially identify CRC cases that might respond to checkpoint inhibitors (CPIs). The subsets of high or low PD1/PD-L1/IDO1 expression stratified by CD48 were accurately associated with prognosis in CRC. In addition, in vitro experiments confirmed that VTCN1(B7-H4)-KD increases anti-PD-L1-mediated NK cell cytotoxicity on CRC tumor cells.

Conclusion

Although the expression of a single immune-checkpoint molecule does not predict the efficacy of immunotherapy in CRC, our findings infer that subsets defined by ICGs are associated with prognosis and imply the possibility that VTCN1 and CD48 serve as new immunotherapeutic targets.

Abnormal expression of the costimulatory molecule B7-H4 in placental chorionic villous and decidual basalis tissues of patients with preeclampsia and HELLP syndrome

BACKGROUND

B7-H4, a checkpoint molecule of the B7 family, regulates a broad spectrum such as T-cell activation, cytokine secretion, tumour progression, and invasion capacities. Our previous data revealed that soluble B7-H4 (sB7-H4) blood serum levels are elevated in women at high risk for the hypertensive pregnancy disorder preeclampsia (PE) in the first trimester, as well as in patients with confirmed early/late-onset PE.

AIM

We here aim to investigate the expression pattern of B7-H4 in placental tissues of PE and HELLP Syndrome versus control group.

METHODS

B7-H4 protein expression and localization were investigated by immunoblotting and co-immunohistochemistry in placental chorionic villous and decidual basalis tissues.

RESULTS

B7-H4 protein was prominently expressed at the cell membrane, in the cytoplasm of the syncytiotrophoblast (STB) and interstitial extravillous trophoblast (EVT). B7-H4 protein levels in placental chorionic villous tissue were significantly higher in women with early-onset/late-onset PE and HELLP, while it was decreased in decidual basalis tissues of early-onset PE and HELLP compared with controls.

CONCLUSION

B7-H4 was inversely expressed in placental chorionic villous and decidual basalis tissues of PE and HELLP patients. The increase in B7-H4 in the STB in PE and HELLP may lead to excessive apical expression and release of soluble B7-H4 in the maternal circulation. In contrast, the decrease in B7-H4 in decidual basalis tissues could be related to the decrease in invasion ability of the EVT in PE. Thus, the current results strongly suggest that B7-H4 is involved in the pathogenesis of PE and HELLP.

Glycosylation of Immune Receptors in Cancer

Evading host immune surveillance is one of the hallmarks of cancer. Immune checkpoint therapy, which aims to eliminate cancer progression by reprogramming the antitumor immune response, currently occupies a solid position in the rapidly expanding arsenal of cancer therapy. As most immune checkpoints are membrane glycoproteins, mounting attention is drawn to asking how protein glycosylation affects immune function. The answers to this fundamental question will stimulate the rational development of future cancer diagnostics and therapeutic strategies.

The Regulatory Cross-Talk between microRNAs and Novel Members of the B7 Family in Human Diseases: A Scoping Review

The members of the B7 family, as immune checkpoint molecules, can substantially regulate immune responses. Since microRNAs (miRs) can regulate gene expression post-transcriptionally, we conducted a scoping review to summarize and discuss the regulatory cross-talk between miRs and new B7 family immune checkpoint molecules, i.e., B7-H3, B7-H4, B7-H5, butyrophilin like 2 (BTNL2), B7-H6, B7-H7, and immunoglobulin like domain containing receptor 2 (ILDR2). The current study was performed using a six-stage methodology structure and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. PubMed, Embase, Scopus, Cochrane, ProQuest, and Google Scholar were systematically searched to obtain the relevant records to 5 November 2020. Two authors independently reviewed the obtained records and extracted the desired data. After quantitative and qualitative analyses, we used bioinformatics approaches to extend our knowledge about the regulatory cross-talk between miRs and the abovementioned B7 family members. Twenty-seven articles were identified that fulfilled the inclusion criteria. Studies with different designs reported gene-miR regulatory axes in various cancer and non-cancer diseases. The regulatory cross-talk between the aforementioned B7 family molecules and miRs might provide valuable insights into the pathogenesis of various human diseases.

B Cells versus T Cells in the Tumor Microenvironment of Malignant Lymphomas. Are the Lymphocytes Playing the Roles of Muhammad Ali versus George Foreman in Zaire 1974?

Malignant lymphomas are a heterogeneous group of malignancies that develop both in nodal and extranodal sites. The different tissues involved and the highly variable clinicopathological characteristics are linked to the association between the lymphoid neoplastic cells and the tissues they infiltrate. The immune system has developed mechanisms to protect the normal tissue from malignant growth. In this review, we aim to explain how T lymphocyte-driven control is linked to tumor development and describe the tumor-suppressive components of the resistant framework. This manuscript brings forward a new insight with regard to intercellular and intracellular signaling, the immune microenvironment, the impact of therapy, and its predictive implications. A better understanding of the key components of the lymphoma environment is important to properly assess the role of both B and T lymphocytes, as well as their interplay, just as two legendary boxers face each other in a heavyweight title final, as was the case of Ali versus Foreman.

Checkpoint regulator B7x is epigenetically regulated by HDAC3 and mediates resistance to HDAC inhibitors by reprogramming the tumor immune environment in colorectal cancer

HDAC inhibitors are efficacious for treating lymphoma, but display limited efficacy in treating solid tumors. Here, we investigated the relationship between HDAC inhibitor resistance and the tumor immune environment in colorectal cancer. Our data indicated that among the investigated immune factors, B7x expression was enhanced in HDAC inhibitor-resistant colorectal cancer models in vitro and in vivo. In addition, gene manipulation results demonstrated that xenograft mice with tumors derived from a B7x-overexpressing CT-26 colorectal cancer cell line were resistant to HDAC inhibitor treatment. Notably, we found that there is a negative relationship between HDAC and B7x expression in both colorectal cancer cell lines and patients’ tumors. Furthermore, our data indicated that elevated expression of B7x was related to a poor prognosis in colorectal tumor patients. Interestingly, treatment with a specific inhibitor or siRNA of HDAC3, but not HDAC2, 6, and 8, resulted in obvious upregulation of B7x expression in colorectal cancer cells. In addition, our data showed that a cell line with high HDAC3 expression and low B7x expression had decreased enrichment of acetylated histone H3 in the promoter region of the gene encoding B7x. This pattern was reversed by addition of HDAC3 inhibitors. Mechanistically, we found that HDAC3 regulated B7x transcription by promoting the binding of the transcription activator C/EBP-α with the B7x promoter region. Importantly, our data indicated that an antibody neutralizing B7x augmented the response to HDAC inhibitor in the colorectal cancer xenograft model and the lung metastasis model by increasing the ratios of both CD4-positive and CD8-positive T cells. In summary, we demonstrated a role of B7x in HDAC inhibitor resistance and identified the mechanism that dysregulates B7x in colorectal cancer. Our work provides a novel strategy to overcome HDAC inhibitor resistance.

Correlation Patterns Among B7 Family Ligands and Tryptophan Degrading Enzymes in Hepatocellular Carcinoma

Mechanisms of dysfunctional T cell immunity in Hepatocellular Carcinoma (HCC) need to be well defined. B7 family molecules provide both co-stimulatory and co-inhibitory signals to T cells while tryptophan degrading enzymes like Indoleamine 2,3 dioxygenase (IDO) and Tryptophan 2,3 Dioxygenase (TDO) mediate tumor immune tolerance. It is necessary to identify their in situ correlative expression, which informs targets for combined immunotherapy approaches. We investigated B7 family molecules, IDO, TDO and immune responsive effectors in the tumor tissues of patients with HCC (n = 28) using a pathway-focused quantitative nanoscale chip real-time PCR. Four best correlative expressions, namely (1) B7-1 & PD-L2, (2) B7-H2 & B7-H3, (3) B7-2 & PD-L1, (4) PD-L1 & PD-L2, were identified among B7 family ligands, albeit they express at different levels. Although TDO expression is higher than IDO, PD-L1 correlates only with IDO but not TDO. Immune effector (Granzyme B) and suppressive (PD-1 and TGF-β) genes correlate with IDO and B7-1, B7-H5, PD-L2. Identification of the in situ correlation of PD-L1, PD-L2 and IDO suggest their cumulative immuno suppressive role in HCC. The distinct correlations among B7-1, B7-2, B7-H2, and B7-H3, correlation of PD-1 with non-cognate ligands such as B7-1 and B7-H5, and correlation of tumor lytic enzyme Granzyme B with IDO and PD-L2 suggest that HCC microenvironment is complexly orchestrated with both stimulatory and inhibitory molecules which together neutralize and blunt anti-HCC immunity. Functional assays demonstrate that both PDL-1 and IDO synergistically inhibit T cell responses. Altogether, the present data suggest the usage of combined immune checkpoint blocking strategies targeting co-inhibitory B7 molecules and IDO for HCC management.

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.

High expression of B7-H3 on stromal cells defines tumor and stromal compartments in epithelial ovarian cancer and is associated with limited immune activation

BACKGROUND

B7-H3 and B7-H4 are highly expressed by many human malignancies making them attractive immunotherapeutic targets. However, their expression patterns and immune contexts in epithelial ovarian cancer have not been well characterized.

METHODS

We used flow cytometry, immunohistochemistry, and genomic analyses to determine the patterns of B7-H3, B7-H4, and PD-L1 expression by tumor, stromal, and immune cells in the ovarian tumor microenvironment (TME). We analyzed immune cell frequency and expression of PD-1, TIM3, LAG3, ICOS, TIA-1, granzyme B, 2B4, CD107a, and GITR on T cells; CD20, CD22, IgD, BTLA, and CD27 on B cells; CD16 on monocytes; and B7-H3, B7-H4, PD-L1, PD-L2, ICOSL, CD40, CD86, and CLEC9a on antigen-presenting cells by flow cytometry. We determined intratumoral cellular location of immune cells using immunohistochemistry. We compared differences in immune infiltration in tumors with low or high tumor-to-stroma ratio and in tumors from the same or unrelated patients.

RESULTS

On non-immune cells, B7-H4 expression was restricted to tumor cells whereas B7-H3 was expressed by both tumor and stromal cells. Stromal cells of the ovarian TME expressed high levels of B7-H3 compared to tumor cells. We used this differential expression to assess the tumor-to-stroma ratio of ovarian tumors and found that high tumor-to-stroma ratio was associated with increased expression of CD16 by monocytes, increased frequencies of PD-1^high CD8⁺ T cells, increased PD-L1 expression by APCs, and decreased CLEC9a expression by APCs. We found that expression of PD-L1 or CD86 on APCs and the proportion of PD-1^high CD4⁺ T cells were strongly correlated on immune cells from tumors within the same patient, whereas expression of CD40 and ICOSL on APCs and the proportion of PD-1^high CD8⁺ T cells were not.

CONCLUSIONS

This study provides insight into the expression patterns of B7-H3 and B7-H4 in the ovarian TME. Further, we demonstrate an association between the tumor-to-stroma ratio and the phenotype of tumor-infiltrating immune cells. We also find that some but not all immune parameters show consistency between peritoneal metastatic sites. These data have implications for the design of immunotherapies targeting these B7 molecules in epithelial ovarian cancer.

Advances and Challenges of Nanoparticle-Based Macrophage Reprogramming for Cancer Immunotherapy

Despite the progress of modern medicine, oncological diseases are still among the most common causes of death of adult populations in developed countries. The current therapeutic approaches are imperfect, and the high mortality of oncological patients under treatment, the lack of personalized strategies, and severe side effects arising as a result of treatment force seeking new approaches to therapy of malignant tumors. During the last decade, cancer immunotherapy, an approach that relies on activation of the host antitumor immune response, has been actively developing. Cancer immunotherapy is the most promising trend in contemporary fundamental and practical oncology, and restoration of the pathologically altered tumor microenvironment is one of its key tasks, in particular, the reprogramming of tumor macrophages from the immunosuppressive M2-phenotype into the proinflammatory M1-phenotype is pivotal for eliciting antitumor response. This review describes the current knowledge about macrophage classification, mechanisms of their polarization, their role in formation of the tumor microenvironment, and strategies for changing the functional activity of M2-macrophages, as well as problems of targeted delivery of immunostimulatory signals to tumor macrophages using nanoparticles.

Tumor cell expression of B7-H4 correlates with higher frequencies of tumor-infiltrating APCs and higher CXCL17 expression in human epithelial ovarian cancer

B7-H4, an immune suppressive member of the B7 family, is highly expressed in a wide variety of human malignancies making it an attractive immunotherapeutic target. However, the association between B7-H4 expression in the tumor microenvironment and the immune infiltrate has not been comprehensively examined. To evaluate the immune tumor microenvironment, we analyzed epithelial ovarian tumors from 28 patients using flow cytometry, immunohistochemistry, functional, and genomic analyses. We determined B7-H4 expression patterns and compared the immune infiltrates of tumors with high and low surface expression of B7-H4. Frequencies and phenotypes of tumor and immune cells were determined using multiple flow cytometry panels. Immunohistochemistry was used to analyze cellular infiltration and location. Publicly available datasets were interrogated to determine intratumoral cytokine and chemokine expression. We found that B7-H4 was predominantly expressed by tumor cells in the epithelial ovarian tumor microenvironment. Surface expression of B7-H4 on tumor cells was correlated with higher levels of infiltrating mature antigen-presenting cells. Further, expression of CXCL17, a monocyte and dendritic cell chemoattractant, correlated strongly with B7-H4 expression. T cells expressed activation markers, but T cells expressing a combination of markers associated with T cell activation/exhaustion phenotype were not prevalent. Overall, our data suggest that B7-H4 is associated with a pro-inflammatory tumor microenvironment.

B7-H4 is highly expressed in aggressive Epstein-Barr virus positive diffuse large B-cell lymphoma and inhibits apoptosis through upregulating Erk1/2 and Akt signalling pathways

Background

B7-H4 is among the B7 family members which may serve as a new targetable immune checkpoint molecule. It was reported that high level of serum B7-H4 level may be correlated with lymphoma. Nevertheless, the role of B7-H4 in Epstein-Barr Virus-Positive diffuse large B cell lymphoma (EBV⁺DLBCL) has not been addressed although it has been suggested that B7-H4 could promote tumor growth and metastatic progression in certain cancers.

Methods

Between January 2005 and November 2017 at the department of Hematology, Shanghai Jiao Tong University School of Medicine affiliated Shanghai General Hospital 260 DLBCL samples were analyzed for EBV-encoded small RNA (EBV-EBER) by in situ hybridization. The expression level of B7-H4 in DLBCL tumor tissue was evaluated by immunohistochemistry. Furthermore, the role of B7-H4 in DLBCL was further investigated in DLBCL cell line.

Results

EBV⁺DLBCL patients suffered from markedly lower overall survival (OS) and progression-free survival (PFS) rates in our study. We showed that B7-H4 was significantly overexpressed in 16 EBV⁺-subgroup cases out of 260 DLBCL patients. We further found that EBV infection in lymphoblast cells led to enhanced expression of B7-H4 followed by increased cell viability and reduced apoptosis. In contrast, inhibition of B7-H4 simultaneously impaired cell viability and induced apoptosis. Mechanistically, inhibiting B7-H4 resulted in decreased phosphorylation Erk 1/2 and Akt.

Conclusion

Our study reveals a critical role of B7-H4 in EBV⁺DLBCL development by regulating cell survival and apoptosis through the Erk and Akt signalling pathways. Targetting B7-H4 may be promising in the therapy of EBV⁺DLBCL.

Combinatorial Approaches With Checkpoint Inhibitors to Enhance Anti-tumor Immunity

Treatment of cancer patients has been recently revolutionized by the application of various immunotherapeutics. However, the response rates are still limited ranging between approximately 20 and 40% suggesting that combinations of immunotherapy with conventional treatment, like chemotherapy, radiation, epigenetic modulators, targeted therapies using small molecules as well as other (immuno) therapeutics, might be an option to increase systemic anti-tumor immunity. It is postulated that different non-immune based therapies in combination with immunotherapies could reprogram the immune suppressive tumor microenvironment and enhance the immunogenicity of tumor cells leading to an improved therapeutic efficacy and a better patients' outcome. Despite there exist various examples of increased objective responses achieved by adding these different therapies to immunotherapies, strategies for rational and evidence-based design of checkpoint inhibitor combinations to maximize the clinical benefit for patients are urgently required. Therefore, the main purpose of this review is to summarize recent results obtained from experimental models and clinical trials to enhance tumor immunogenicity by combining immunotherapy with other therapeutic options to maximize patients' outcome and minimize adverse events.

Identification of three subtypes of triple-negative breast cancer with potential therapeutic implications

Background

Heterogeneity and lack of targeted therapies represent the two main impediments to precision treatment of triple-negative breast cancer (TNBC), and therefore, molecular subtyping and identification of therapeutic pathways are required to optimize medical care. The aim of the present study was to define robust TNBC subtypes with clinical relevance.

Methods

Gene expression profiling by means of DNA chips was conducted in an internal TNBC cohort composed of 238 patients. In addition, external data (n = 257), obtained by using the same DNA chip, were used for validation. Fuzzy clustering was followed by functional annotation of the clusters. Immunohistochemistry was used to confirm transcriptomics results: CD138 and CD20 were used to test for plasma cell and B lymphocyte infiltrations, respectively; MECA79 and CD31 for tertiary lymphoid structures; and UCHL1/PGP9.5 and S100 for neurogenesis.

Results

We identified three molecular clusters within TNBC: one molecular apocrine (C1) and two basal-like-enriched (C2 and C3). C2 presented pro-tumorigenic immune response (immune suppressive), high neurogenesis (nerve infiltration), and high biological aggressiveness. In contrast, C3 exhibited adaptive immune response associated with complete B cell differentiation that occurs in tertiary lymphoid structures, and immune checkpoint upregulation. External cohort subtyping by means of the same approach proved the robustness of these results. Furthermore, plasma cell and B lymphocyte infiltrates, tertiary lymphoid structures, and neurogenesis were validated at the protein levels by means of histological evaluation and immunohistochemistry.

Conclusion

Our work showed that TNBC can be subcategorized in three different subtypes characterized by marked biological features, some of which could be targeted by specific therapies.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1148-6) contains supplementary material, which is available to authorized users.

The prognostic value of B7-H4 in pancreatic cancer: Systematic review and meta-analysis

BACKGROUND

There were many reports suggesting that different kinds of tumors can express B7-H4; however, the prognostic value in cancer was still unclearly. Therefore, we conducted a meta-analysis to investigate the relationship between overexpression of B7-H4 with the prognostic value in pancreatic cancer patients.

MATERIALS AND METHODS

The Pubmed, Embase, Cochrane Library, Ovid, Web of Science, and Chinese research database (including CBM, CNKI, and WAN FANG) were searched for related literature published until October 12, 2017. The pooled odds ratios (ORs) and/or pooled hazard ratios (HRs) for clinical pathological factors and overall survival (OS) were calculated and analyzed using Stata software. To assess whether an individual study had an impact on the result, sensitivity analysis was performed for all included individual studies using the fixed-effects model. Publication bias was evaluated using Egger's and Begg's tests.

RESULTS

Data from 6 observational studies including 442 patients were summarized in this meta-analysis, and each study was eligible for inclusion based on included and exclude criteria. The pooled results indicated that the B7-H4 overexpression could predict the presentation of lymph node metastasis (OR = 3.94, 95% CI: 1.22-12.66, P = .022), advanced TNM stage (T = the extent of the primary tumor, N = regional lymph nodes, M = distant metastases) (III+IV vs I+II; OR = 7.63, 95% CI: 2.46-23.66, P < .001), and the poor OS (HR = 3.00, 95%CI = 2.20-4.10, P < .001) in PC patients.

CONCLUSIONS

This study reveals that high expression of B7-H4 is an unfavorable prognostic factor for patients with pancreatic cancer. These results may guide the clinical management of this patient population.

Tumor-expressed immune checkpoint B7x promotes cancer progression and antigen-specific CD8 T cell exhaustion and suppressive innate immune cells

B7x (B7-H4 or B7S1) is a coinhibitory member of the B7 immune checkpoint ligand family that regulates immune function following ligation with its unknown cognate receptors. B7x has limited expression on normal tissues, but is up-regulated on solid human tumors to inhibit anti-tumor immunity and associates with poor clinical prognosis. We assessed the contribution of cytokine stimuli to induce surface B7x expression on cancer cells and the role of tumor-expressed B7x in a murine pulmonary metastasis model, and finally evaluated the potential interaction between B7x and Neuropilin-1, a suggested potential cognate receptor. We showed that pro-inflammatory and anti-inflammatory cytokines IFNγ, TNFα, and IL-10 did not induce expression of B7x on human or murine cancer cells. Following i.v. injection of CT26, a murine colon cancer cell line in the BALB/c background, we observed a significant increase in tumor burden in the lung of B7x-expressing CT26 mice compared to B7x-negative parental CT26 control mice. This was marked by a significant increase in M2 tumor associated macrophages and antigen-specific CD8 T cell exhaustion. Finally, we found through multiple systems that there was no evidence for B7x and Neuropilin-1 direct interaction. Thus, the B7x pathway has an essential role in modulating the innate and adaptive immune cell infiltrate in the tumor microenvironment with its currently unknown cognate receptor(s).

B7-H4 overexpression is essential for early hepatocellular carcinoma progression and recurrence

B7-H4, another member of costimulatory molecule, has been shown to be overexpressed in multiple types of tumors, including hepatocellular carcinoma (HCC). However, the specific biological role of B7-H4 in HCC still needs to be further explored. In this study, we observed that B7-H4 was highly overexpressed in HCC tissues and cells, and its overexpression strongly correlated with patient's TNM stage, overall survival and early recurrence. Downregulation of B7-H4 significantly suppressed cell growth, invasion, and stemness of HCC by inducing apoptosis in the in vitro experiment. In addition, depletion of B7-H4 could help restore CD8⁺ T anti-tumor immunity by elevating the expression and secretion levels of CD107a, granzyme A, granzyme B, perforin and IFN-γ. In a xenografted mouse model of HCC, stable depletion of B7-H4 resulted in significantly smaller mean tumor volume and less mean tumor weight after 30 days of growth, compared to the control group. Together, our results provide insights into the diverse functions of B7-H4 involved in the pathogenesis, recurrence and anti-tumor immunity of HCC, indicating B7-H4 as a novel and effective approach for future treatment strategies that benefits anticancer therapy.