The CD28-B7 Family in Anti-Tumor Immunity: Emerging Concepts in Cancer Immunotherapy

First-in-class small molecule inhibitors of ICOS/ICOSL interaction as a novel class of immunomodulators

The interaction of the inducible co-stimulator (ICOS) with its ligand (ICOSL) plays key roles in T-cell differentiation and activation of T-cell to B-cell functions. The ICOS/ICOSL pathway is a validated target for T-cell lymphomas induced by the proliferation of T-follicular helper (Tfh) cells. Moreover, the inhibition of ICOS/ICOSL interaction can decrease the enhancement of immunosuppressive regulatory T cells (Tregs) in both hematologic malignancies and solid tumors. However, targeting ICOS/ICOSL interaction is currently restricted to monoclonal antibodies (mAbs) and there are no small molecules in existence that can block ICOS/ICOSL. To fill this gap, we report herein the first time-resolved fluorescence resonance energy transfer (TR-FRET) assay to evaluate the ability of small molecules to inhibit ICOS/ICOSL interaction. Implementation of the developed TR-FRET assay in high-throughput screening (HTS) of a focused chemical library resulted in the identification of AG-120 as a first-in-class inhibitor of ICOS/ICOSL interaction. We further employed docking studies and molecular dynamics (MD) simulations to identify the plausible mechanism of blocking ICOS/ICOSL complex formation by AG-120. Using the structure-activity relationship (SAR) by catalog approach, we identified AG-120-X with an IC50 value of 4.68 ± 0.47 μM in the ICOS/ICOSL TR-FRET assay. Remarkably, AG-120-X revealed a dose-dependent ability to block ICOS/ICOSL interaction in a bioluminescent cellular assay based on co-culturing Jurkat T cells expressing ICOS and CHO-K1 cells expressing ICOSL. This work will pave the way for future drug discovery efforts aiming at the development of small molecule inhibitors of ICOS/ICOSL interaction as potential therapeutics for cancer as well as other diseases.

Cooperative Treatment of Gastric Cancer Using B7-H7 siRNA and Docetaxel; How Could They Modify Their Effectiveness?

Purpose

Despite the high prevalence of gastric cancer (GC), drug resistance is a major problem for effective chemotherapy. B7-H7 is a novel member of the B7 superfamily and is expressed in most common cancers. However, the role of B7-H7 on the aggressiveness of GC and chemosensitivity has remained unknown. Therefore, this study was designed to assess the effect of B7-H7 suppression using small interference RNA (siRNA) in combination with docetaxel on GC cells.

Methods

MTT test was applied to determine the IC50 of docetaxel and the combined effect of B7-H7 siRNA and docetaxel on the viability of the MKN-45 cells. To determine B7-H7, BCL-2, BAX, and caspase-3-8-9 genes expression, qRT-PCR was performed. Furthermore, flow cytometry was applied to evaluate apoptosis and the cell cycle status. Finally, to evaluate the effect of this combination therapy on migratory capacity and colony-forming ability, wound healing assay and colony formation test were employed, respectively.

Results

B7-H7 suppression increased the chemo-sensitivity of MKN-45 cells to docetaxel. The expression of B7-H7 mRNA was reduced after using B7-H7 siRNA and docetaxel in MKN-45 GC cells. Also, B7-H7 suppression alongside docetaxel reduced cell migration and colony formation rate, arrested the cell cycle at the G2-M phase, and induced apoptosis by modulating the expression of apoptotic target genes.

Conclusion

B7-H7 plays a significant role in the chemo-sensitivity and pathogenesis of GC. Therefore, B7-H7 suppression, in combination with docetaxel, may be a promising therapeutic approach in treating GC.

T cells, NK cells, and tumor-associated macrophages in cancer immunotherapy and the current state of the art of drug delivery systems

The immune system provides full protection for the body by specifically identifying 'self' and removing 'others'; thus protecting the body from diseases. The immune system includes innate immunity and adaptive immunity, which jointly coordinate the antitumor immune response. T cells, natural killer (NK) cells and tumor-associated macrophages (TAMs) are the main tumor-killing immune cells active in three antitumor immune cycle. Cancer immunotherapy focusses on activating and strengthening immune response or eliminating suppression from tumor cells in each step of the cancer-immunity cycle; thus, it strengthens the body's immunity against tumors. In this review, the antitumor immune cycles of T cells, natural killer (NK) cells and tumor-associated macrophages (TAMs) are discussed. Co-stimulatory and co-inhibitory molecules in the three activity cycles and the development of drugs and delivery systems targeting these molecules are emphasized, and the current state of the art of drug delivery systems for cancer immunotherapy are summarized.

B7-H7: A potential target for cancer immunotherapy

Cancer immunotherapy enhances the body's immunity against tumors by mitigating immune escape. Compared with traditional chemotherapy, immunotherapy has the advantages of fewer drugs, a wider range of action and fewer side effects. B7-H7 (also known as HHLA2, B7y) is a member of the B7 family of costimulatory molecules that was discovered more than 20 years ago. B7-H7 is mostly expressed in organs such as the breast, intestine, gallbladder and placenta and is detected predominantly in monocytes/macrophages in the immune system. Its expression is upregulated after stimulation by inflammatory factors such as lipopolysaccharide and interferon-γ. B7-H7/transmembrane and immunoglobulin domain containing 2 (TMIGD2) and killer cell immunoglobulin-like receptor, three Ig domains and long cytoplasmic tail 3 (KIR3DL3)-B7-H7 are the two currently confirmed signaling pathways for B7-H7. An increasing number of studies have demonstrated that B7-H7 is widely present in a variety of human tumor tissues, especially in programmed cell death-1 (PD-L1)-negative human tumors. B7-H7 promotes tumor progression, disrupts T-cell-mediated antitumor immunity, and inhibits immune surveillance. B7-H7 also triggers tumor immune escape and is associated with clinical stage, depth of tumor infiltration, metastasis, prognosis, and survival related to different tumor types. Multiple studies have shown that B7-H7 is a promising immunotherapeutic target. Herein, review the current literature on the expression, regulation, receptors and function of B7-H7 and its regulation/function in tumors.

An immune checkpoint-based signature predicts prognosis and chemotherapy response for patients with small cell lung cancer

BACKGROUND

Therapeutic options for small cell lung cancer (SCLC), a particularly lethal malignancy, remain limited. Members of the B7-CD28 family are compelling targets for immune checkpoint blockade strategies, which involve activating, inhibiting, and fine-tuning the T cell immune response. However, their clinical features and significance have not been explored comprehensively.

METHOD

We enrolled 228 patients with an initial diagnosis of SCLC, including 77 cases from Cbioportal and a validation cohort of 151 cases with qPCR data. Kaplan-Meier analysis and LASSO Cox model were used to identify a signature based on the B7-CD28 family, which was applied for accurate prediction of chemotherapy benefit and prognosis for SCLC patients. In addition, we applied bioinformatics analysis to explore potential signature-related molecular mechanisms and the immune landscape.

RESULTS

The mutation profiles of healthy tissues and SCLC tissues were distinct. A signature consisting of seven genes (CD86, ICOSLG, CD276, CD28, CTLA-4, PDCD1, and TMIGD2) was identified and applied to group patients based on risk level (high-risk and low-risk), producing two groups for which survival outcomes differed significantly (HR = 3.81, 95% CI: 2.16-6.74, P < 0.001). The immune checkpoint-based signature accurately predicted patient outcomes for the selected training and validation sets. Notably, low-risk patients were more likely to benefit from chemotherapy and showed greater immune activation. Additionally, time-dependent ROC curves and C-index analysis confirmed that the immune checkpoint-based signature has excellent predictive power for prognosis and chemotherapy benefit compared to clinically recognized parameters. Finally, multivariate analysis confirmed the identified signature as an independent risk factor for prognosis and chemotherapeutic response.

CONCLUSION

We systematically obtained a comprehensive molecular profile for B7-CD28 family members in SCLC patients, from which we produced a reliable and robust prognostic immune checkpoint-based signature with the potential to improve prognostic stratification and therapy strategies for SCLC patients.

Multi-omics analyses of CD276 in pan-cancer reveals its clinical prognostic value in glioblastoma and other major cancer types

BACKGROUND

CD276 (also known as B7-H3) is one of the most important immune checkpoints of the CD28 and B7 superfamily, and its abnormal expression is closely associated with various types of cancer. It has been shown that CD276 is able to inhibit the function of T cells, and that this gene may potentially be a promising immunotherapy target for different types of cancer.

METHODS

Since few systematic studies have been published on the role of CD276 in cancer to date, the present study has employed single-cell sequencing and bioinformatics methods to analyze the expression patterns, clinical significance, prognostic value, epigenetic alterations, DNA methylation level, tumor immune cell infiltration and immune functions of CD276 in different types of cancer. In order to analyze the potential underlying mechanism of CD276 in glioblastoma (GBM) to assess its prognostic value, the LinkedOmics database was used to explore the biological function and co-expression pattern of CD276 in GBM, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed. In addition, a simple validation of the above analyses was performed using reverse transcription-quantitative (RT-q)PCR assay.

RESULTS

The results revealed that CD276 was highly expressed, and was often associated with poorer survival and prognosis, in the majority of different types of cancer. In addition, CD276 expression was found to be closely associated with T cell infiltration, immune checkpoint genes and immunoregulatory interactions between lymphoid and a non-lymphoid cell. It was also shown that the CD276 expression network exerts a wide influence on the immune activation of GBM. The expression of CD276 was found to be positively correlated with neutrophil-mediated immunity, although it was negatively correlated with the level of neurotransmitters, neurotransmitter transport and the regulation of neuropeptide signaling pathways in GBM. It is noteworthy that CD276 expression was found to be significantly higher in GBM compared with normal controls according to the RT-qPCR analysis, and the co-expression network, biological function and chemotherapeutic drug sensitivity of CD276 in GBM were further explored. In conclusion, the findings of the present study have revealed that CD276 is strongly expressed and associated with poor prognosis in most types of cancer, including GBM, and its expression is strongly associated with T-cell infiltration, immune checkpoint genes, and immunomodulatory interactions between lymphocytes and non-lymphoid cells.

CONCLUSIONS

Taken together, based on our systematic analysis, our findings have revealed important roles for CD276 in different types of cancers, especially GBM, and CD276 may potentially serve as a biomarker for cancer.

The potential of B7-H6 as a therapeutic target in cancer immunotherapy

Immune checkpoints are vital molecules that regulate T-cell function by activation or inhibition. Among the immune checkpoint molecules, the B7-family proteins are significantly involved in the immune escape of tumor cells. By binding to inhibitory receptors, they can suppress T-cell-mediated immunity. B7-family proteins are found at various stages of tumor microenvironment formation and promote tumorigenesis and tumor progression. B7-H6 (encoded by gene NCR3LG1) is a prominent member of the family. It has unique immunogenic properties and is involved in natural killer (NK) cell immunosurveillance by binding to the NKp30 receptor. High B7-H6 expression in certain tumor types and shortage of or low expression in healthy cells - except in cases of inflammatory or microbial stimulation - have made the protein an attractive target of research activities in recent years. The avoidance of NK-mediated B7-H6 detection is a mechanism through which tumor cells escape immune surveillance. The stimulation of tumorigenesis occurs by suppressing caspase cascade initiation and anti-apoptosis activity stimulation via the STAT3 pathway. The B7-H6-NKp30 complex on the tumor membrane activates the NK cells and releases both tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). B7-H6 is highly expressed in a wide range of tumor cells, including glioma, hematologic malignant tumors, and breast cancer cells. Clinical examination of cancer patients indicated that the expression of B7-H6 is related to distant metastasis status and permits postoperative prognosis. Because of its unique properties, B7-H6 has a high potential be utilized as a biological marker for cancer diagnosis and prognosis, as well as a target for novel treatment options.

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.

Co-deficiency of B7-H3 and B7-H4 identifies high CD8 + T cell infiltration and better prognosis in pancreatic cancer

Background

Immunotherapy is a novel hotspot for the treatment of pancreatic adenocarcinoma (PAAD). However, potential biomarkers which could identify the inflamed tumor microenvironment (TME) are urgently required.

Methods

In the present study, we measured the levels of B7-H3, B7-H4, and major tumor-infiltrating immune cells (TIICs) using bioinformatics analyses and immunohistochemistry (IHC) staining on PAAD samples represented in the tissue microarray (TMA) format. Statistical analysis and figures exhibition were performed using R 4.1.0, SPSS 26.0, and GraphPad Prism 6.0.

Results

B7-H3 and B7-H4 were up-regulated in PAAD compared with para-tumor tissues, and their expression exhibited no tight correlation in PAAD tissues. B7-H3 and B7-H4 were lowly expressed in well-differentiated PAAD tissues and correlated with poorly differentiated grades. Besides, single B7-H3 or B7-H4 expression exhibited limited prognostic value, but co-deficiency of B7-H3 and B7-H4 predicted a better prognosis in PAAD. Moreover, co-deficiency of B7-H3 and B7-H4 indicated immuno-hot tumors with high CD8 + T cell infiltration.

Conclusions

Overall, combined B7-H3 and B7-H4 expression is a promising stratification strategy to assess prognosis and immunogenicity in PAAD, which could be used as a novel classifier in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09294-w.

Different clinical significance of novel B7 family checkpoints VISTA and HHLA2 in human lung adenocarcinoma

Background: VISTA and HHLA2 are two recently identified members of the B7 homologue family of immune-regulatory molecules. But the expression patterns and clinical significance of VISTA and HHLA2 in lung adenocarcinoma (LUAD) remain largely unknown. Methods: Immunohistochemistry was performed to examine the expression of VISTA, HHLA2, PD-L1 and CD8⁺ tumor-infiltrating lymphocytes in 74 cases of LUAD. The expression of VISTA, HHLA2, PD-L1, CD68 and CD8 proteins was detected by multiplex immunofluorescence staining in the LUAD tissues. Results: High expression of VISTA and HHLA2 was observed in LUAD compared with noncancerous tissues. High VISTA expression in immune cells predicted a high mortality rate and worse survival. Conclusion: VISTA and HHLA2 are potential immunotherapeutic targets that possess different prognostic significance in LUAD.

A new biological triangle in cancer: intestinal microbiota, immune checkpoint inhibitors and antibiotics

Cancer immunotherapy has revolutionized the treatment of many malignant tumors. Although immune checkpoint inhibitors (ICIs) can reactivate the anti-tumor activity of immune cells, sensitivity to immune checkpoint inhibitor therapy depends on the complex tumor immune processes. In recent years, numerous researches have demonstrated the role of intestinal microbiota in immunity and metabolism of the tumor microenvironment, as well as the efficacy of immunotherapy. Epidemiological studies have further demonstrated the efficacy of antibiotic therapy on the probability of patients' response to ICIs and predictability of the short-term survival of cancer patients. Disturbance to the intestinal microbiota significantly affects ICIs-mediated immune reconstitution and is considered a possible mechanism underlying the development of adverse effects during antibiotic-based ICIs treatment. Intestinal microbiota, antibiotics, and ICIs have gradually become important considerations for the titer of immunotherapy. In the case of immunotherapy, the rational use of antibiotics and intestinal microbiota is expected to yield a better prognosis for patients with malignant tumors.

The Expression of Three Negative Co-Stimulatory B7 Family Molecules in Small Cell Lung Cancer and Their Effect on Prognosis

Background

In recent years, immune checkpoint inhibitors have shown significant effects in a variety of solid tumors. However, due to the low incidence of small cell lung cancer (SCLC) and its unclear mechanism, immune checkpoints in SCLC have not been fully studied.

Methods

We evaluated the expression of PD-L1, B7-H3, and B7-H4 in 115 SCLC tissue specimens using immunohistochemistry. The clinical data of patients with SCLC were retrospectively reviewed to investigate three negative co-stimulatory B7 family molecules’ ability to affect the prognosis of SCLC.

Results

Among the SCLC patients with complete follow-up data (n = 107), sixty-nine (64.49%) expressed moderate to high B7-H3 levels, which correlated positively with tumor sizes (P < 0.001). Eighty (74.77%) patients expressed moderate to high B7-H4 levels, which correlated positively with metastases (P = 0.049). The positive expression of B7-H3 and B7-H4 correlated significantly with shortened overall survival (OS) (B7-H3, P = 0.006; B7-H4, P = 0.019). PD-L1 was positively expressed only in 13.08% of cancer tissues, and there was no significant correlation with prognosis. The Cox proportional hazards regression showed that B7-H3 was an independent prognostic indicator of OS (P = 0.028; HR = 2.125 [95% CI = 0.985-4.462]).

Conclusions

Our results suggest that B7-H3 has a negative predictive effect on SCLC. This outcome provides a theoretical basis for the subsequent research on immune checkpoint inhibitors targeting B7-H3.

Immune checkpoint inhibitors for the management of advanced non-small-cell lung carcinoma: a meta-analysis

This study is a meta-analysis assessing the safety and efficacy of programmed cell death-1/cell death-ligand 1 (PD-1/PD-L1) inhibitors in order to improve their efficacy in advanced non-small-cell lung cancer. We retrieved studies of anti-PD-1/PD-L1 therapies for non-small-cell lung cancer from electronic databases; 17 clinical trials were analyzed. The pooled hazard ratios for overall and progression-free survival (PFS), and the odds ratios (ORs) for the objective response rate (ORR) and adverse effects were calculated using Review Manager 5.3. The pooled hazard ratios for overall and PFS were 0.69 and 0.74, respectively, and the pooled OR for the ORR was 1.78, implying a significant improvement in overall survival (OS), PFS, and ORR with administration of PD-1/PD-L1 inhibitors. In subgroup analysis, the ORs of the ORR were 2.48 in PD-L1 positive versus negative tumors, and 0.99 for a high dose of PD-1/PD-L1 inhibitors versus a low dose. The ORs for the occurrence of any treatment-related adverse effects and grades 3-5 treatment-related adverse effects were 0.33 and 0.30, respectively, suggesting a good safety profile. PD-1/PD-L1 immunotherapy has superior outcomes in terms of the ORR, OS, and PFS with tolerable adverse effects when compared with chemotherapy.

B7-1 and GM-CSF enhance the anti-tumor immune effect of DC-tumor fusion vaccine in the treatment of prostate cancer

The treatment of castration-resistant prostate cancer (CRPC) is always a difficulty in the clinic. Most patients with localized tumor eventually develop CRPC, even if hormone therapy is initially effective. Increasing evidence shows immunotherapy has special advantages compared with traditional therapy in cancer treatment. In this study, we constructed the DC-PC-3 fusion vaccine with B7-1- and GM-CSF-specific modification, and studied its ability to stimulate specific immune response and anti-tumor effect in vitro. The results showed that fusion of DC and tumor cells can improve the expression of associated antigens of DCs. DC-tumor fusion vaccine can strongly promote T cell proliferation and IFN-γ secretion and induce a significant tumor-specific cytotoxic T lymphocyte response. In addition, the B7-1/GM-CSF-modified fusion vaccine showed a more significant anti-tumor effect and greater ability to stimulate the immune response than that without specific modification in vitro. Thus, GM-CSF/B7-1-modified fusion vaccine might be used as a potential therapy strategy for prostate cancer.

Therapeutic Interventions into Innate Immune Diseases by Means of Aptamers

The immune system plays a crucial role in the body's defense system against various pathogens, such as bacteria, viruses, and parasites, as well as recognizes non-self- and self-molecules. The innate immune system is composed of special receptors known as pattern recognition receptors, which play a crucial role in the identification of pathogen-associated molecular patterns from diverse microorganisms. Any disequilibrium in the activation of a particular pattern recognition receptor leads to various inflammatory, autoimmune, or immunodeficiency diseases. Aptamers are short single-stranded deoxyribonucleic acid or ribonucleic acid molecules, also termed "chemical antibodies," which have tremendous specificity and affinity for their target molecules. Their features, such as stability, low immunogenicity, ease of manufacturing, and facile screening against a target, make them preferable as therapeutics. Immune-system-targeting aptamers have a great potential as a targeted therapeutic strategy against immune diseases. This review summarizes components of the innate immune system, aptamer production, pharmacokinetic characteristics of aptamers, and aptamers related to innate-immune-system diseases.

Disease-related cellular protein networks differentially affected under different EGFR mutations in lung adenocarcinoma

It is unclear how epidermal growth factor receptor EGFR major driver mutations (L858R or Ex19del) affect downstream molecular networks and pathways. This study aimed to provide information on the influences of these mutations. The study assessed 36 protein expression profiles of lung adenocarcinoma (Ex19del, nine; L858R, nine; no Ex19del/L858R, 18). Weighted gene co-expression network analysis together with analysis of variance-based screening identified 13 co-expressed modules and their eigen proteins. Pathway enrichment analysis for the Ex19del mutation demonstrated involvement of SUMOylation, epithelial and mesenchymal transition, ERK/mitogen-activated protein kinase signalling via phosphorylation and Hippo signalling. Additionally, analysis for the L858R mutation identified various pathways related to cancer cell survival and death. With regard to the Ex19del mutation, ROCK, RPS6KA1, ARF1, IL2RA and several ErbB pathways were upregulated, whereas AURK and GSKIP were downregulated. With regard to the L858R mutation, RB1, TSC22D3 and DOCK1 were downregulated, whereas various networks, including VEGFA, were moderately upregulated. In all mutation types, CD80/CD86 (B7), MHC, CIITA and IFGN were activated, whereas CD37 and SAFB were inhibited. Costimulatory immune-checkpoint pathways by B7/CD28 were mainly activated, whereas those by PD-1/PD-L1 were inhibited. Our findings may help identify potential therapeutic targets and develop therapeutic strategies to improve patient outcomes.

A review of the research progress in T-lymphocyte immunity and cervical cancer

Cervical cancer develops as a result of T-cell immune evasion by human papillomavirus (HPV). T-cell immunity requires the participation of many factors, such as antigen-presenting cells (APCs), cytokines, co-stimulatory molecules, etc. HPV vaccines are promising treatments to prevent HPV infection and cervical cancer. This article mainly provides a summary of the number and function changes of T cells during HPV infection and cervical cancer development. Studies on t-cell immunotherapy, which is expected to become a new treatment for cervical cancer after surgery, radiotherapy, and chemotherapy, are also reviewed in this article.

B7-H3 and B7-H4 Expression in Breast Cancer and Their Association with Clinicopathological Variables and T Cell Infiltration

OBJECTIVES

B7-H3 and B7-H4 proteins are expressed in breast cancer tissues, but their relationships with respect to tumor immune surveillance and outcomes in breast cancer are not conclusive.

METHODS

We first examined B7-H3 and B7-H4 mRNA expression in the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) datasets. Next, mRNA and protein expression were assessed by RNAscope in situ hybridization (ISH) and immunohistochemistry in 10 pairs of breast cancer and matched normal tissues. Immunohistochemical staining of B7-H3, B7-H4, CD3, and CD8 was performed in tissue microarray slides containing 198 breast cancer samples. Association of B7-H3 and B7-H4 expression with survival was verified using the publicly accessible BreastMark tool.

RESULTS

B7-H3 and B7-H4 mRNA expression were significantly higher in breast cancer samples in the TCGA dataset than in normal breast tissues in the GTEx dataset. RNAscope ISH and immunohistochemistry showed that B7-H3 and B7-H4 mRNA and protein appeared to be mainly expressed in cancer cells. Expression of B7-H3 and B7-H4 tended to be associated with low-density scores of stromal tumor-infiltrating lymphocytes (TILs) as well as molecular subtypes. Expressions of B7-H3 and B7-H4 were negatively correlated with stromal CD3+ and CD8+ T cell infiltration density. B7-H3 and B7-H4 expression was not associated with survival, which was verified by BreastMark analysis.

CONCLUSION

Expression levels of B7-H3 and B7-H4 were independent of clinical outcomes of breast cancer. There was an inverse relationship between the expression of B7-H3 and B7-H4 in breast cancer and the density of stromal TILs and CD8+ T lymphocytes. This inverse relationship may represent a promising target in the field of breast cancer immunotherapy.

Engineering Newcastle Disease Virus as an Oncolytic Vector for Intratumoral Delivery of Immune Checkpoint Inhibitors and Immunocytokines

Newcastle disease virus (NDV) is an attractive candidate for oncolytic immunotherapy due to its ability to replicate in tumor cells and potentially to overcome the inherently immunosuppressive nature of the tumor microenvironment. The advent of checkpoint blockade immunotherapy over the past few years represents a paradigm shift in cancer therapy. However, the prevalence of severe immune-related adverse events with CTLA4 and PD1 pathway blockade in clinical studies, especially in combination therapy groups, is a cause for concern. Immunotherapies with cytokines have also been extensively explored, but they have been associated with adverse events in clinical trials. Oncolytic vectors engineered to express checkpoint blockade antibodies and cytokines could provide an avenue for reducing the clinical toxicity associated with systemic therapy by concentrating the immunomodulatory payload at the site of disease. In this study, we engineered six different recombinant viruses: NDVs expressing checkpoint inhibitors (rNDV-anti-PD1 and rNDV-anti-PDL1); superagonists (rNDV-anti-CD28); and immunocytokines, where the antibodies are fused to an immunostimulatory cytokine, such as interleukin 12 (IL-12) (rNDV-anti-CD28-murine IL-12 [mIL-12], rNDV-anti-PD1-mIL-12, and rNDV-anti-PDL1-mIL-12). These six engineered viruses induced tumor control and survival benefits in both highly aggressive unilateral and bilateral B16-F10 murine melanoma models, indicative of an abscopal effect. The data represent a strong proof of concept on which further clinical evaluation could build.IMPORTANCE Checkpoint inhibitor therapy has shown tremendous efficacy, but also frequent and often severe side effects-especially when multiple drugs of the class are used simultaneously. Similarly, many investigational immunotherapy agents, which have shown promise in animal models, have failed in clinical trials due to dose-limiting toxicity when administered systemically. This study utilized a murine melanoma model to evaluate the efficacy of intratumoral injections of recombinant NDVs engineered to express multiple immunotherapeutic proteins with well-documented side effects in humans. Our results indicate that intratumoral administration of these recombinant NDVs, particularly when combined with systemic CTLA4 checkpoint inhibition, exerts a robust effect in treated and nontreated tumors, indicative of a systemic antitumoral response. The intratumoral delivery of rNDVs expressing immunotherapeutic proteins may be an effective method of targeting the immune cell populations most relevant for antitumoral immunity and allowing us to restrict the use of systemic immunotherapy agents.

Teleost cytotoxic T cells

Cell-mediated cytotoxicity is one of the major mechanisms by which vertebrates control intracellular pathogens. Two cell types are the main players in this immune response, natural killer (NK) cells and cytotoxic T lymphocytes (CTL). While NK cells recognize altered target cells in a relatively unspecific manner CTLs use their T cell receptor to identify pathogen-specific peptides that are presented by major histocompatibility (MHC) class I molecules on the surface of infected cells. However, several other signals are needed to regulate cell-mediated cytotoxicity involving a complex network of cytokine- and ligand-receptor interactions. Since the first description of MHC class I molecules in teleosts during the early 90s of the last century a remarkable amount of information on teleost immune responses has been published. The corresponding studies describe teleost cells and molecules that are involved in CTL responses of higher vertebrates. These studies are backed by functional investigations on the killing activity of CTLs in a few teleost species. The present knowledge on teleost CTLs still leaves considerable room for further investigations on the mechanisms by which CTLs act. Nevertheless the information on teleost CTLs and their regulation might already be useful for the control of fish diseases by designing efficient vaccines against such diseases where CTL responses are known to be decisive for the elimination of the corresponding pathogen. This review summarizes the present knowledge on CTL regulation and functions in teleosts. In a special chapter, the role of CTLs in vaccination is discussed.

Associations of B7-H3 and B7-H4 Expression in Ductal Carcinoma In Situ of the Breast With Clinicopathologic Features and T-Cell Infiltration

B7-H3 and B7-H4 play an inhibitory role in T-cell function by limiting proliferation and cytokine production. Information about B7-H3 and B7-H4 expression in ductal carcinoma in situ (DCIS) remains uncertain. The objective of this study was to evaluate the expression levels of B7-H3 and B7-H4 in DCIS and their associations with clinicopathologic features and T-cell infiltration. B7-H3 and B7-H4 mRNA and protein expression levels in 8 pairs of DCIS tissues and matched normal adjacent tissues were examined by RNAscope in situ hybridization and immunohistochemistry analysis. Immunohistochemical staining of B7-H3, B7-H4, CD3, and CD8 was performed for 79 DCIS samples using tissue microarray. RNAscope in situ hybridization and immunohistochemistry analysis revealed that expression levels of B7-H3 and B7-H4 in DCIS tissues were higher than those in corresponding normal tissues. B7-H3 and B7-H4 mRNA and protein appeared to be mainly expressed in DCIS carcinoma cells. High B7-H3 and B7-H4 expression was observed in 58 (73.4%) and 62 (78.5%) cases with DCIS, respectively. High B7-H3 expression was significantly associated with high-nuclear grade and presence of comedo-type necrosis (both P<0.05). B7-H3 expression in HR/HER2 subtype was higher than that in HR/HER2 subtype (P<0.05). B7-H3 and B7-H4 expression levels were negatively related to the density of CD3 and CD8 T-cell infiltrates. B7-H3 and B7-H4 may play an important role in immune surveillance mechanisms of DCIS. They might be useful targets to develop immune-based therapy to alter or prevent DCIS progression.

B7-CD28 gene family expression is associated with prognostic and immunological characteristics of diffuse large B-cell lymphoma

The B7-CD28 gene family plays a key role in regulating cellular immunity and is closely related to tumorigenesis and immune evasion. Here, we explored associations between clinical and immune features and B7-CD28 gene family expression in Gene Expression Omnibus (GEO) datasets representing 1812 diffuse large B-cell lymphoma (DLBCL) patients. This included 414 in the GSE10846 training cohort and 470 and 928 patients in the GSE31312 and GSE117556 validation cohorts, respectively. Four survival-associated genes identified in the GSE10846 cohort by univariate Cox analysis were incorporated into a multivariate analysis, ultimately establishing a three-gene risk signature. Risk scores assigned based on expression of these genes were validated by Kaplan–Meier and multivariable Cox analyses in the remaining datasets and in important clinical subsets. High-risk patients had shorter overall survival and, in some cases, progression-free survival than low-risk patients. Additionally, expression of programmed cell death 1 (PD-1) and programmed death ligand 1 (PD-L1), as well as several other important immune checkpoint genes, differed between high-risk and low-risk patients, as did the proportions of various immune-infiltrating cells. Finally, further analysis confirmed that these B7-CD28 genes play important roles in immune responses altered in DLBCL.

High expression of B7‑H2 or B7‑H3 is associated with poor prognosis in hepatocellular carcinoma

B7 family members have been associated with the signaling transduction pathways underlying tumor immune evasion in hepatocellular carcinoma. In the present study, associations between the clinical characteristics of patients with hepatocellular carcinoma (HCC) and the expression of B7-H2 and B7-H3 were analyzed. A total of 63 formalin-fixed and paraffin-embedded HCC tissues were collected to be used as a tissue microarray. Following this, the association between B7-H2/B7-H3 and the prognosis of patients with HCC was analyzed using Pearson's χ² test, the Kaplan-Meier method and receiver operating characteristic curve analysis. The results demonstrated that the expression of B7-H2 was significantly associated with recurrence (within 1 year) in patients with HCC (P<0.01), and that the expression of B7-H3 was associated with recurrence (within 1 year), metastasis and 2-year overall survival rate in patients with HCC (P<0.01, P=0.036 and P=0.016, respectively). In addition, the combined expression of B7-H2 and B7-H3 was associated with prognostic factors, including recurrence (within 1 year) and survival rate (within 2 years), in patients with HCC. In particular, an increased area under the curve was achieved when the combined expression of B7-H2 and B7-H3 was considered, compared with that for α-fetoprotein. Taken together, these results indicated that B7-H2- and/or B7-H3-positive expression indicates a poor clinical outcome for patients, and the combination of B7-H2 and B7-H3 may be a preferential prognostic biomarker in patients with HCC.

Immune Checkpoint Inhibitor-induced Reinvigoration of Tumor-infiltrating CD8+ T Cells is Determined by Their Differentiation Status in Glioblastoma

PURPOSE

Immune checkpoint inhibitors (ICI) are used for the treatment of various cancers, but clinical trials of anti-programmed cell death protein 1 (PD-1) with patients with recurrent glioblastoma (GBM) have failed to show clinical benefits. In this study, we examined the differentiation status of CD8⁺ tumor-infiltrating lymphocytes (TIL) from patients with primary GBM and their reinvigoration by ICIs to understand the nature of T-cell exhaustion in GBM.

EXPERIMENTAL DESIGN

We isolated TILs from 98 patients with newly diagnosed GBM and examined the expression of immune checkpoint receptors and T-cell transcription factors using flow cytometry. TILs were ex vivo stimulated with anti-CD3 in the presence of anti-PD-1 and/or anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) and their proliferation assessed.

RESULTS

CD8⁺ TILs had significantly increased expression of immune checkpoint receptors, including PD-1 and CTLA-4, compared with peripheral blood CD8⁺ T cells. Among CD8⁺ TILs, PD-1⁺ cells exhibited more terminally differentiated phenotypes (i.e., Eomes^hiT-bet^lo) than PD-1^- cells. These data were confirmed by analyzing NY-ESO-1₁₅₇-specific CD8⁺ TILs. Evaluating the proliferation of CD8⁺ TILs after ex vivo stimulation with anti-CD3 and anti-PD-1, we found that proliferation inversely correlated with the percentage of Eomes^hiT-bet^lo cells among PD-1⁺CD8⁺ TILs. When anti-CTLA-4 was used in combination with anti-PD-1, an additional increase in CD8⁺ TIL proliferation was observed in patients with low percentages of Eomes^hiT-bet^lo CD8⁺ TILs, who responded well to anti-PD-1 in ex vivo assays, but not in patients with high percentages of Eomes^hiT-bet^lo CD8⁺ TILs, who did not respond to anti-PD-1.

CONCLUSIONS

In primary GBM, the differentiation status of CD8⁺ TILs determines their reinvigoration ability upon ICI treatment.

A Phase 2 Study to Assess the Immunomodulatory Capacity of a Lecithin-based Delivery System of Curcumin in Endometrial Cancer

Curcumin is a botanical with anti-tumor and immunomodulatory properties. We hypothesized that curcumin supplementation might influence inflammatory biomarker levels in endometrial carcinoma (EC). In this open-label, non-randomized phase 2 study (NCT02017353), seven EC patients consumed 2 g/day Curcumin Phytosome (CP) orally for 2 weeks. Blood was taken at baseline, days 1, 7, 14, and 21. The following analytes were measured: curcuminoids and metabolites, 56 inflammatory biomarkers, COX-2, frequencies of myeloid-derived suppressor cells, dendritic cells and NK cells, expression of MHC molecules on leukocytes and monocytes and activation/memory status of T cells. Patients completed quality of life (QoL) questionnaires at baseline and end of treatment. Curcumin metabolites were detectable in plasma upon CP intake. CP downregulated MHC expression levels on leukocytes (P = 0.0313), the frequency of monocytes (P = 0.0114) and ICOS expression by CD8⁺ T cells (P = 0.0002). However, CP upregulated CD69 levels on CD16⁻ NK cells (P = 0.0313). No differences were observed regarding inflammatory biomarkers, frequencies of other immune cell types, T cell activation and COX-2 expression. A non-significant trend to improved QoL was observed. Overall, CP-induced immunomodulatory effects in EC were modest without significant QoL changes. Given the small population and the observed variability in inter-patient biomarker levels, more research is necessary to explore whether benefits of CP can be obtained in EC by different supplementation regimens.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT02017353; www.clinicaltrialsregister.eu, identifier 2013-001737-40.

Analysis of the Expression and Regulation of PD-1 Protein on the Surface of Myeloid-Derived Suppressor Cells (MDSCs)

Myeloid-derived suppressor cells (MDSCs) that are able to suppress T cell function are a heterogeneous cell population frequently observed in cancer, infection, and autoimmune disease. Immune checkpoint molecules, such as programmed death 1 (PD-1) expressed on T cells and its ligand (PD-L1) expressed on tumor cells or antigen-presenting cells, have received extensive attention in the past decade due to the dramatic effects of their inhibitors in patients with various types of cancer. In the present study, we investigated the expression of PD-1 on MDSCs in bone marrow, spleen, and tumor tissue derived from breast tumor-bearing mice. Our studies demonstrate that PD-1 expression is markedly increased in tumor-infiltrating MDSCs compared to expression in bone marrow and spleens and that it can be induced by LPS that is able to mediate NF-κB signaling. Moreover, expression of PD-L1 and CD80 on PD-1⁺ MDSCs was higher than on PD-1⁻ MDSCs and proliferation of MDSCs in a tumor microenvironment was more strongly induced in PD-1⁺ MDSCs than in PD-1⁻ MDSCs. Although we could not characterize the inducer of PD-1 expression derived from cancer cells, our findings indicate that the study on the mechanism of PD-1 induction in MDSCs is important and necessary for the control of MDSC activity; our results suggest that PD-1⁺ MDSCs in a tumor microenvironment may induce tumor development and relapse through the modulation of their proliferation and suppressive molecules.

B7-H3 and B7-H4 expression in phyllodes tumors of the breast detected by RNA in situ hybridization and immunohistochemistry: Association with clinicopathological features and T-cell infiltration

Phyllodes tumors are rare biphasic breast tumors with the potential for both local recurrence and distant metastasis. The aberrant expression of B7-H3 and B7-H4 B7 molecules could be potential targets for future development of immunotherapeutic approaches. This work was undertaken to evaluate the expression of B7-H3 and B7-H4 in phyllodes tumors and assess the association with the grade and clinical behavior of phyllodes tumors. In addition, the roles of B7-H3 and B7-H4 in the regulation of tumor immune surveillance were evaluated by assessing the relationship between B7-H3/B7-H4 expression and T-cell infiltration. The messenger RNA and protein expression of B7-H3/B7-H4 were determined by RNAscope in situ hybridization and immunohistochemistry, respectively, in 101 phyllodes tumors (60 benign, 26 borderline, and 15 malignant) using a tissue microarray. Immunohistochemistry for CD3 and CD8 was also performed. B7-H3 messenger RNA and protein appeared to be concentrated mainly in the stromal compartment of phyllodes tumors. However, B7-H4 messenger RNA and protein were undetectable in the stromal compartment of phyllodes tumors. Stromal B7-H3 messenger RNA and protein expression were noted in 10 (16.7%) and 31 (51.7%) of 60 benign phyllodes tumors, 12 (46.1%) and 20 (76.9%) of 26 borderline phyllodes tumors, and 10 (66.7%) and 13 (86.7%) of 15 malignant phyllodes tumors, respectively. Stromal B7-H3 messenger RNA and protein expression increased as phyllodes tumors progressed from benign to borderline and finally to the malignant grade (Pearson's R = 0.411, p < 0.001 and Pearson's R = 0.293, p = 0.003, respectively). The recurrence rate was higher in the stromal B7-H3 messenger RNA or protein-positive group than in the negative group, but this difference was not significant. Stromal B7-H3 protein expression inversely correlated with the densities of CD3⁺ and CD8⁺ T-cell infiltrates ( p = 0.001 and p = 0.027, respectively). These results suggest that B7-H3 is involved in the progression of phyllodes tumors and may contribute to their immune surveillance.

Association of B7-H4, PD-L1, and tumor infiltrating lymphocytes with outcomes in breast cancer

B7-H4 (VTCN1) is a member of the CD28/B7 family of immune co-inhibitory molecules. The relationship of tumor and stromal B7-H4 protein expression with PD-L1, tumor infiltrating lymphocytes (TILs) and its association with clinico-pathological variables are not well defined. Herein, we explore the expression level of B7-H4 protein in breast cancer and evaluate its association with TILs, levels of PD-L1 expression, and clinico-pathological characteristics in two independent populations. In this study, we used multiplexed automated quantitative immunofluorescence (QIF) to measure the levels of B7-H4 and PD-L1 protein and determined TILs through pathologist assessment of H&E-stained preparations in over a thousand breast cancer cases from two institutions represented in tissue microarray format. Associations between the marker levels, major clinico-pathological variables, and survival were analyzed. We detected B7-H4 protein was highly expressed in both breast cancer and stromal cells. Its expression was independent of breast cancer intrinsic subtypes. PD-L1 expression was higher in triple negative breast cancers. Neither B7-H4 nor PD-L1 were associated with survival in breast cancer. Our study shows there is a mutually exclusive pattern of B7-H4 with both tumor PD-L1 expression and TILs in all breast cancers, independent of breast cancer intrinsic subtype. This exclusive pattern suggests that some breast tumors may preferentially use one B7-related immune evasion mechanism/pathway. This could explain the clinical benefit that is seen only in a fraction of patients with immune checkpoint inhibitors directed exclusively towards PD-L1 in breast cancer.

Single-Cell Transcriptomics in Cancer Immunobiology: The Future of Precision Oncology

Cancer is a heterogeneous and complex disease. Tumors are formed by cancer cells and a myriad of non-cancerous cell types that together with the extracellular matrix form the tumor microenvironment. These cancer-associated cells and components contribute to shape the progression of cancer and are deeply involved in patient outcome. The immune system is an essential part of the tumor microenvironment, and induction of cancer immunotolerance is a necessary step involved in tumor formation and growth. Immune mechanisms are intimately associated with cancer progression, invasion, and metastasis; as well as to tumor dormancy and modulation of sensitivity to drug therapy. Transcriptome analyses have been extensively used to understand the heterogeneity of tumors, classifying tumors into molecular subtypes and establishing signatures that predict response to therapy and patient outcomes. However, the classification of the tumor cell diversity and specially the identification of rare populations has been limited in these transcriptomic analyses of bulk tumor cell populations. Massively-parallel single-cell RNAseq analysis has emerged as a powerful method to unravel heterogeneity and to study rare cell populations in cancer, through unsupervised sampling and modeling of transcriptional states in single cells. In this context, the study of the role of the immune system in cancer would benefit from single cell approaches, as it will enable the characterization and/or discovery of the cell types and pathways involved in cancer immunotolerance otherwise missed in bulk transcriptomic information. Thus, the analysis of gene expression patterns at single cell resolution holds the potential to provide key information to develop precise and personalized cancer treatment including immunotherapy. This review is focused on the latest single-cell RNAseq methodologies able to agnostically study thousands of tumor cells as well as targeted single-cell RNAseq to study rare populations within tumors. In particular, we will discuss methods to study the immune system in cancer. We will also discuss the current challenges to the study of cancer at the single cell level and the potential solutions to the current approaches.

A B7-CD28 family based signature demonstrates significantly different prognoses and tumor immune landscapes in lung adenocarcinoma

B7 family ligands and CD28 family receptors have complicated interaction for modulating immune functions. They play a central role in response to immunotherapy and outcome of patients with lung adenocarcinoma (LUAD). Thus, we analyzed B7-CD28 family gene expression profiles in LUAD and generated a signature to predict prognosis and immune host status. B7-CD28 family gene expression profiles and clinical data of LUAD from The Cancer Genome Atlas (TCGA) were analyzed. In the training cohort, prognostic association was assessed and then a prognostic signature was built with stepwise multivariable Cox analysis. The signature was validated by Kaplan-Meier and multivariable Cox analysis in several published gene expression datasets and a Fudan University cohort. Expression of immune cell populations and other immunotherapy predictors was further investigated. In TCGA LUAD cohort, eight B7-CD28 family genes had prognostic association with p values <0.05. Stepwise regression generated a gene signature including two genes, CD28 and CD276. Signature high-risk cases had worse overall survival (OS) and disease-free survival (DFS) in three published gene expression datasets and a Fudan University validation cohort. The B7-CD28 family based signature also significantly stratified OS and DFS in important clinical subsets, including stage I-II and EGFR mutant subsets. Signature high- and low-risk tumor had significantly different expressions of PD-L1 and tumor infiltrating leukocytes. The B7-CD28 family based signature demonstrates significantly different prognoses and tumor immune landscapes in LUAD. Whether it could serve as potential biomarkers for immunotherapy needs further investigation.

B7-H3 promotes metastasis, proliferation, and epithelial-mesenchymal transition in lung adenocarcinoma

Background

Lung adenocarcinoma is the most common pathological type of lung cancer. However, the mechanisms underlying its development are still poorly understood. B7-H3 was discovered as a new member of the B7 costimulatory family.

Methods

We detected the expression status of B7-H3 protein in lung adenocarcinoma tissues, and evaluated the relationship of B7-H3 expression and patients' prognosis. Then, we silenced its expression in A549 cells by transient siRNA transfection to ascertain the function of B7-H3 in lung adenocarcinoma cells. Western blotting was used to detect the expression of epithelial-mesenchymal transition (EMT) related proteins.

Results

We found that B7-H3 overexpressed in lung adenocarcinoma. It is correlated with lymph node metastasis, distant metastasis, and disease stage. The Cox regression analysis showed that B7-H3 might serve as an independent prognostic marker of lung adenocarcinoma. We also found that B7-H3 promoted proliferation, invasion and migration of A549 cells in vitro. B7-H3 also could promote EMT progression by regulating EMT-related molecules.

Conclusion

B7-H3 is a potential target for the treatment of lung adenocarcinoma.

CCL5-deficiency enhances intratumoral infiltration of CD8+ T cells in colorectal cancer

Colorectal cancer (CRC) is the third most common solid tumor in the world and shows resistance to several immunotherapies, particularly immune checkpoint blockade which has therapeutic effects on many other types of cancer. Cytotoxic CD8⁺ T cell has been considered as one of the main populations of effector immune cells in antitumor immunity; however, the absence of CD8⁺ T cells in the central tumor area has become a major obstacle for solid tumor immunotherapy, particularly for CRC. Thus, novel therapeutic strategies that could promote CD8⁺ T cells to accumulate in the central tumor area are urgently needed. Here, we demonstrated that CCL5-deficiency delayed tumor growth and metastasis via facilitating CD8⁺ T cells to accumulate into tumor site in CRC mouse models. Furthermore, CCL5-deficiency could upregulate PD-1 and PD-L1 expression and reduce the resistance to anti-PD-1 antibody therapy in CRC mouse model. Mechanically, the results of RNA-sequencing, in vitro coculture system and hypoxia measurements demonstrated that knockdown of CCL5 could result in the metabolic disorders in CD11b^hiF4/80^low TAMs and suppress the expression of S100a9 to promote the migration of CD8⁺ T cells in the tumor microenvironment. These findings were verified by the data of clinical samples from CRC patients, suggesting that CCL5 may provide a potential therapeutic target for the combined PD-1-immunotherapy of CRC.

Expression of Programmed Death-Ligand 1 by Human Colonic CD90+ Stromal Cells Differs Between Ulcerative Colitis and Crohn's Disease and Determines Their Capacity to Suppress Th1 Cells

Background and Aims

The role of programmed cell death protein 1 (PD-1) and its ligands in the dysregulation of T helper immune responses observed in the inflammatory bowel disease (IBD) is unclear. Recently, a novel concept emerged that CD90⁺ colonic (myo)fibroblasts (CMFs), also known as stromal cells, act as immunosuppressors, and are among the key regulators of acute and chronic inflammation. The objective of this study was to determine if the level of the PD-1 ligands is changed in the IBD inflamed colonic mucosa and to test the hypothesis that changes in IBD-CMF-mediated PD-1 ligand-linked immunosuppression is a mechanism promoting the dysregulation of Th1 cell responses.

Methods

Tissues and cells derived from Crohn's disease (CD), ulcerative colitis (UC), and healthy individuals (N) were studied in situ, ex vivo, and in culture.

Results

A significant increase in programmed death-ligand 1 (PD-L1) was observed in the inflamed UC colonic mucosa when compared to the non-inflamed matched tissue samples, CD, and healthy controls. UC-CMFs were among the major populations in the colonic mucosa contributing to the enhanced PD-L1 expression. In contrast, PD-L1 expression was decreased in CD-CMFs. When compared to CD-CMFs and N-CMFs, UC-CMFs demonstrated stronger suppression of IL-2, Th1 transcriptional factor Tbet, and IFN-γ expression by CD3/CD28-activated CD4⁺ T cells, and this process was PD-L1 dependent. Similar observations were made when differentiated Th1 cells were cocultured with UC-CMFs. In contrast, CD-CMFs showed reduced capacity to suppress Th1 cell activity and addition of recombinant PD-L1 Fc to CD-CMF:T cell cocultures partially restored the suppression of the Th1 type responses.

Conclusion

We present evidence showing that increased PD-L1 expression suppresses Th1 cell activity in UC. In contrast, loss of PD-L1 expression observed in CD contributes to the persistence of the Th1 inflammatory milieu in CD. Our data suggest that dysregulation of the Th1 responses in the inflamed colonic mucosa of IBD patients is promoted by the alterations in PD-L1 expression in the mucosal mesenchymal stromal cell compartment.

Knockdown of B7H6 inhibits tumor progression in triple-negative breast cancer

The B7 family, the most common family of secondary signaling molecules, consists of eight cell-surface proteins, which regulate the T-cell mediated immune response by delivering co-inhibitory or co-stimulatory signals through their corresponding ligands. Among them, natural killer cell cytotoxicity receptor 3 ligand 1 (NCR3LG1, also known as B7H6) has been reported as a new member, and is involved in tumor progression of various types of human cancer. However, the role of B7H6 in triple-negative breast cancer (TNBC) remains unknown. In the present study, western blotting was performed to determine the protein expression levels of B7H6 in a normal mammary epithelial cell line (MCF-10A), non-TNBC breast cancer cell lines (MCF-7 and AU565) and TNBC cell lines (MDA-MB-231 and MDA-MB-468). B7H6 was knocked down using small interfering RNA, and an MTT assay was performed to determine proliferation ability, flow cytometry was used to analyze apoptosis, and Transwell and wound-healing assays were performed to measure migration ability. Expression of proliferation-associated proteins (SMAD family member 4 and β-catenin) and apoptosis-associated proteins (BCL2 associated X, BCL2 apoptosis regulator and caspase-3) were analyzed by western blotting. The results demonstrated that B7H6 was highly expressed in TNBC cells, and that knockdown of B7H6 inhibited cell proliferation and migration, and promoted apoptosis. Furthermore, the results revealed that proliferation and apoptosis-associated proteins were altered in the B7H6-knockdown MDA-MB-231 cells. In conclusion, the present study demonstrated that B7H6 may have significant roles in the regulation of cell proliferation, apoptosis and migration of TNBC cells.

B7-H6 expression is induced by lipopolysaccharide and facilitates cancer invasion and metastasis in human gliomas

Although great progress has been made in treatment regimens, gliomas are still incurable and the 5-year survival remains poor. Studies focusing on molecules that regulate tumorigenesis or tumor immunity may provide potential therapeutic strategies for patients with glioma. B7-H6 is selectively expressed in tumor cells and plays vital roles in host immune responses. In this study, we demonstrated that B7-H6 was expressed in glioma cell lines, including CRT, U251, SHG-44, SF-295, TG-905 and U373, and tumor tissues isolated from glioma patients. Moreover, the expression levels of B7-H6 were significantly correlated with glioma grade. Previous studies reported that inflammatory mediators and cytokines induced the expression of B7 family members including programmed death-ligand 1, B7-H2 and B7-H4. Therefore, we explored the regulation of B7-H6 expression in gliomas and showed that lipopolysaccharide induced the expression of B7-H6 in glioma cells. To further analyze the roles of B7-H6 in gliomas, the expression of B7-H6 in glioma cells was knocked down. The results of cell counting kit-8, colony formation, wound healing, and transwell migration and invasion assays demonstrated that the proliferation, migration and invasion of glioma cells were inhibited after knocking down B7-H6. To elucidate the specific mechanisms of B7-H6 function in cancer progression, we examined the expression levels of proteins involved in cell apoptosis, migration and invasion. We demonstrated that the expression levels of E-cadherin and Bcl-2 associated X protein increased, and the expression levels of vimentin, N-cadherin, matrix metalloproteinase-2, matrix metalloproteinase-9 and survivin decreased after knocking down B7-H6. In conclusion, B7-H6 plays important roles in glioma, and targeting B7-H6 may provide a novel therapeutic strategy for glioma patients.

Overexpression of HHLA2, a member of the B7 family, is associated with worse survival in human colorectal carcinoma

Background

Colorectal carcinoma (CRC) is one of the most common malignancies, and immunotherapy has opened a new field of cancer treatment in recent years. Generally, CRC does not benefit from immunotherapy. HHLA2, a member of the B7 family, is a novel immune checkpoint molecule, and the prognostic value of HHLA2 in CRC patients and the association between HHLA2 expression and clinicopathological characteristics remains unknown.

Materials and methods

This study included 63 patients diagnosed with CRC, and their resected specimens were obtained and constructed as a tissue microarray. Expression of HHLA2 and CD8 was detected by the double immunohistochemistry method. Based on follow-up data, correlations of HHLA2 expression and clinicopathological features, including overall survival, in CRC patients were evaluated.

Results

High HHLA2 expression was detected in CRC tumor tissues, compared to the adjacent noncancerous tissues. HHLA2 expression level was significantly related to the depth of invasion (P=0.044) and CD8⁺ T-cell infiltration status (P=0.016), and predicted high mortality rate (P=0.035). HHLA2 acted as an independent predictive factor in the overall survival of CRC patients (P=0.039, hazard ratio=2.162, 95% CI 1.041–3.084).

Conclusion

HHLA2 expression is upregulated in CRC patients, and HHLA2 is an independent prognostic factor of overall survival of CRC patients. High HHLA2 expression is closely correlated with CD8 T-cell infiltration status and can predict poor prognosis in CRC patients.

Immunohistochemical and Image Analysis-Based Study Shows That Several Immune Checkpoints are Co-expressed in Non-Small Cell Lung Carcinoma Tumors

INTRODUCTION

The understanding of immune checkpoint molecules' co-expression in non-small cell lung carcinoma (NCLC) is important to potentially design combinatorial immunotherapy approaches.

METHODS

We studied 225 formalin-fixed, paraffin-embedded tumor tissues from stage I-III NCLCs - 142 adenocarcinomas (ADCs) and 83 squamous cell carcinomas (SCCs) - placed in tissue microarrays. Nine immune checkpoint markers were evaluated; four (programmed death ligand 1 [PD-L1], B7-H3, B7-H4, and indoleamine 2,3-dioxygenase 1 [IDO-1]) expressed predominantly in malignant cells (MCs) and five (inducible T cell costimulator, V-set immunoregulatory receptor, T-cell immunoglobulin mucin family member 3, lymphocyte activating 3, and OX40) expressed mostly in stromal tumor-associated inflammatory cells (TAICs). All markers were examined using a quantitative image analysis and correlated with clinicopathologic features, TAICs, and molecular characteristics.

RESULTS

Using above the median value as positive expression in MCs and high density of TAICs expressing those markers, we identified higher expression of immune checkpoints in SCC than ADC. Common simultaneous expression by MCs was PD-L1 + B7-H3 + IDO-1 in ADC and PD-L1 + B7-H3, or B7-H3 + B7-H4, in SCC. TAICs expressing checkpoint were significantly higher in current smokers than in never smokers. Almost all the immune checkpoint markers showed positive correlation with TAICs expressing inflammatory cell markers. KRAS-mutant ADC specimens showed higher expression of PD-L1 in MCs and of B7-H3, T-cell immunoglobulin mucin family member 3, and IDO-1 in TAICs than wild type. Kaplan-Meier survival curves showed worse prognosis in ADC patients with higher B7-H4 expression by MCs.

CONCLUSIONS

We found frequent immunohistochemical co-expression of immune checkpoints in surgically resected NCLC tumors and correlated with tumor histology, smoking history, tumor size, and the density of inflammatory cells and tumor mutational status.

Prognostic role of B7-H4 in patients with non-small cell lung cancer: A meta-analysis

B7 homolog 4 (B7-H4) has been recently reported to be a prognostic marker in non-small cell lung cancer (NSCLC) in some studies. However, the results remained conflicting. Thus, we aimed to comprehensively assess the association between B7-H4 expression and prognosis of NSCLC patients by performing a meta-analysis. Relevant publications were thoroughly searched of PubMed, Embase, Web of Science and China National Knowledge Infrastructure (CNKI). The pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were applied to evaluate the effects. A total of 9 studies comprising 1444 patients were included in this meta-analysis. B7-H4 overexpression was associated with presence of lymph node metastasis (OR=3.59, 95%CI=2.39-5.38, p<0.001; fixed effect), advanced TNM stage (OR=2.36, 95%CI=1.2-4.67, p=0.013; random effect), and poor differentiation (OR=2.11, 95%CI=1.12-3.99, p=0.021; fixed effect). However, B7-H4 had no significant correlation with gender, age or histology in NSCLC. Furthermore, in a fixed effects model, the results indicated that B7-H4 overexpression was significantly associated with poor OS (HR=2.03, 95%CI=1.41-2.92, p<0.001). This meta-analysis demonstrated that high B7-H4 expression is an unfavorable prognostic factor in NSCLC. Because few studies were included for meta-analysis and almost all included studies were performed on Chinese patients, therefore; large scale prospective studies are needed to verify our results.

Inducible Co-Stimulator (ICOS) as a potential therapeutic target for anti-cancer therapy

INTRODUCTION

The recent success of checkpoint-inhibitors in cancer treatment paved the way for the development of new strategies of agonist and antagonist agents against B7 superfamily members. Inducible Co-Stimulator (ICOS), a co-stimulatory receptor for T-cell enhancement, arouses interest. Areas covered: We performed an extensive literature search with PUBMED using the keywords 'ICOS' and 'cancer' to discuss its involvement in oncogenesis, its expression in different malignancies, and its targeting in relevant preclinical studies. We also searched the Clinicaltrials.gov database for recent updates on early phase clinical trials. Expert opinion: ICOS/ICOSL axis has a dual effect and might participate in anti-tumour T cell response as well as a pro-tumour response due to its connection with regulatory T-cells (Tregs) suppressive activity. Therefore, both antagonist and agonist antibodies might be of interest in the targeting ICOS/ICOSL pathway for cancer treatment. In preclinical studies, ICOS agonist monoclonal antibodies (mAbs) have shown to potentiate the effect of inhibitory checkpoint blockade. In contrast, antagonistic anti-ICOS mAbs could not only inhibit lymphoid tumour cells expressing ICOS, but also dampen immunosuppressive Tregs. Two agonist and one antagonist mAbs are evaluated in phase I/II trials. Efficacy, safety, and combination strategies with anti-ICOS agonist or antagonist have yet to be specified.

Assessment of combined expression of B7-H3 and B7-H4 as prognostic marker in esophageal cancer patients

The co-stimulatory ligands of B7-family have been confirmed to play an important role in negatively regulating the T-cell mediated anti-tumor immunity. In addition, these inhibitory molecules are also aberrantly expressed on various human cancers tissues, and significantly associated with cancer progression and patients' poor prognoses. We have previously reported that B7-H3 and B7-H4 ligands are highly expressed in human esophageal cancer tissues. Herein, we tried to further analyze the value of their combined expression on prognostic prediction for esophageal cancer patients. We found that the combined expression of both B7-H3 and B7-H4 could be used as a valuable risk factor for predicting the prognosis of esophageal cancer patients (P=0.003). Moreover the status of these patients with high expression of both B7-H3 and B7-H4, was positively and significantly associated with the tumor invasion depth (P=0.0414) and TNM stage (P=0.0414). The Cox multivariate proportional hazards regression analysis revealed that the tumor size (P=0.007), the TNM stage (P=0.024) and the status of both B7-H3 and B7-H4 high expression (P=0.011), could be used as an independent risk factor for predicting patients' postoperative prognosis, respectively. In conclusion, our data indicated that the combined application of B7-H3 and B7-H4 expression can be effectively used as a prognostic marker in esophageal cancer patients.

Expression of B7-H2 on CD8+ T cells in colorectal cancer microenvironment and its clinical significance

The knowledge about B7-H2 expression in tumor is growing, but many questions remain unresolved. Especially in human tumor microenvironment, little studies were done. To explore the expression and clinical significance of B7-H2 on T cells in colorectal cancer microenvironment, fresh tumor tissues and paired non-tumor tissues collected from 25 patients with colorectal cancer were made to research B7-H2 expression on the infiltrating T cells including CD8⁺ T cells and CD4⁺ T cells. Also, tumor bearing mice were sacrificed on day 5, day 10, day 15, day 20, day 25 and flow cytometry was used to analyze B7-H2 expression on CD8⁺ T cells and CD4⁺ T cells in mouse tumors and spleens. Then, it was found that B7-H2 expression on CD8⁺ T cells in patients' tumor tissues was significantly higher than in non-tumor tissues. The expression of B7-H2 on CD8⁺ T cells in tumor microenvironment was significantly higher in patients with age ≤60 years old and the stage I-II. The expression level of B7-H2 on CD8⁺ T cells in mouse tumors and spleens both reached the highest level at the early stage of inoculation (on day 5), decreased to the lowest level on day 10 and day 15 separately, and then gradually increased. In mouse spleens, B7-H2 expression on CD8⁺ T cells was all significantly higher than on CD4⁺ T cells in five time periods. So, in this study, it was found that B7-H2 expression on CD8⁺ T cells in tumor microenvironment was closely related to the progression of colorectal cancer.

PD-1/PD-L1 in disease

Aim: Expression of PD-1 on T/B cells regulates peripheral tolerance and autoimmunity. Binding of PD-1 to its ligand, PD-L1, leads to protection against self-reactivity. In contrary, tumor cells have evolved immune escape mechanisms whereby overexpression of PD-L1 induces anergy and/or apoptosis of PD-1 positive T cells by interfering with T cell receptor signal transduction. PD-L1 and PD-1 blockade using antibodies are in human clinical trials as an alternative cancer treatment modality. Areas covered: We describe the role of PD-1/PD-L1 in disease in the context of autoimmunity, neurological disorders, stroke and cancer. Conclusion: For immunotherapy/vaccines to be successful, the expression of PD-L1/PD-1 on immune cells should be considered, and the combination of checkpoint inhibitors and vaccines may pave the way for successful outcomes to disease.

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

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

The tissue distribution and significance of B7-H4 in laryngeal carcinoma

The costimulatory signals CD28 and B7 have been shown to control tumor invasion and metastasis by regulating T cell activation, whereas the distribution characteristics of B7-associated proteins in laryngeal carcinoma (LC) tissue are still unclear. Here, the expression of members of the B7 superfamily, including B7-H1 (PD-L1), B7-DC (PD-L2) and B7-H4, in fifty-two LC samples was determined by immunohistochemistry, and the relationship between B7-H4 and epithelial-mesenchymal transition (EMT)-associated markers was further assessed by immunofluorescence double staining. Furthermore, the human LC cell lines, Hep-2 and TU212 cells, were further transfected to overexpress B7-H4, and cell invasion and metastasis were analyzed. The results showed that B7-H1, B7-DC and B7-H4 were expressed in the tumor cells, and their expression was restricted to the cell membrane and the cytoplasm. The positive rates of these molecules in the tumor tissues were 57.7% (30/52), 32.7% (17/52) and 34.6% (18/52), respectively. Interestingly, double immunofluorescence staining showed that B7-H4 is coexpression with EMT-related markers, including p-Smad2/3, Snail and Vimentin, in carcinoma cells. Moreover, overexpression of B7-H4 in Hep-2 cells promotes the expression of pSmad2/3 and Snail by activating AKT-STAT3 signaling. Transwell and wound-healing assays demonstrated that B7-H4 enhanced both Hep-2 and TU212 cell invasion and metastasis. Our results suggest that B7-H4 transmits feedback signaling to tumor cells and promotes invasion and metastasis by promoting EMT progression. Therefore, blocking B7-H4 signaling might be a novel treatment strategy for LC.

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.

Trial Watch: Immunostimulatory monoclonal antibodies for oncological indications

The goal of cancer immunotherapy is to establish new or boost pre-existing anticancer immune responses that eradicate malignant cells while generating immunological memory to prevent disease relapse. Over the past few years, immunomodulatory monoclonal antibodies (mAbs) that block co-inhibitory receptors on immune effectors cells - such as cytotoxic T lymphocyte-associated protein 4 (CTLA4), programmed cell death 1 (PDCD1, best known as PD-1) - or their ligands - such as CD274 (best known as PD-L1) - have proven very successful in this sense. As a consequence, many of such immune checkpoint blockers (ICBs) have already entered the clinical practice for various oncological indications. Considerable attention is currently being attracted by a second group of immunomodulatory mAbs, which are conceived to activate co-stimulatory receptors on immune effector cells. Here, we discuss the mechanisms of action of these immunostimulatory mAbs and summarize recent progress in their preclinical and clinical development.

QSAR, docking, ADMET, and system pharmacology studies on tormentic acid derivatives for anticancer activity

To explore the anticancer compounds from tormentic acid derivatives, a quantitative structure-activity relationship (QSAR) model was developed by the multiple linear regression methods. The developed QSAR model yielded a high activity-descriptors relationship accuracy of 94% referred by regression coefficient (r² = .94) and a high activity prediction accuracy of 91%. The QSAR study indicates that chemical descriptors, chiV5, T_T_Cl_7, T_2_T_4, SsCH3count, and Epsilon3 are significantly correlated with anticancer activity. This validated model was further been used for virtual screening and thus identification of new potential breast cancer inhibitors. Lipinski's rule of five, ADMET risk and synthetic accessibility are used to filter false positive hits. Filtered compounds were then docked to identify the possible target binding pocket, to obtain a set of aligned ligand poses and to prioritize the predicted active compounds. The scrutinized compounds, as well as their metabolites, were predicted and analyzed for different pharmacokinetics parameters such as absorption, distribution, metabolism, excretion, and toxicity. Finally, the top-ranked compound NB-12 was evaluated by system pharmacology approach. Later studied the metabolic networks, disease biomarker networks, pathway maps, drug-target networks and generate significant gene networks. The strategy applied in this research work may act as a framework for rational design of potential anticancer drugs.

Adoptively transferred Vγ9Vδ2 T cells show potent antitumor effects in a preclinical B cell lymphomagenesis model

A central issue for adoptive cellular immunotherapy is overcoming immunosuppressive signals to achieve tumor clearance. While γδ T cells are known to be potent cytolytic effectors that can kill a variety of cancers, it is not clear whether they are inhibited by suppressive ligands expressed in tumor microenvironments. Here, we have used a powerful preclinical model where EBV infection drives the de novo generation of human B cell lymphomas in vivo, and autologous T lymphocytes are held in check by PD-1/CTLA-4-mediated inhibition. We show that a single dose of adoptively transferred Vδ2+ T cells has potent antitumor effects, even in the absence of checkpoint blockade or activating compounds. Vδ2+ T cell immunotherapy given within the first 5 days of EBV infection almost completely prevented the outgrowth of tumors. Vδ2+ T cell immunotherapy given more than 3 weeks after infection (after neoplastic transformation is evident) resulted in a dramatic reduction in tumor burden. The immunotherapeutic Vδ2+ T cells maintained low cell surface expression of PD-1 in vivo, and their recruitment to tumors was followed by a decrease in B cells expressing PD-L1 and PD-L2 inhibitory ligands. These results suggest that adoptively transferred PD-1lo Vδ2+ T cells circumvent the tumor checkpoint environment in vivo.