B7-H3 belongs to the B7 superfamily, a group of molecules that costimulate or downmodulate T cell responses. Although it has been shown that B7-H3 can inhibit T cell responses, several studies, most of them performed in murine systems, found B7-H3 to act in a co-stimulatory manner. In addition, B7-H3 is also expressed in various human cancers and is correlated with the poor outcome of cancer patients. The functional role of B7-H3 in cancer is still controversially discussed. In the present study, we compared B7-H3 expression in normal gastric tissues and gastric cancer tissue specimens and determined the effects of low B7-H3 expression on the human gastric cancer cell line SGC-7901 by using RNAi. B7-H3 expression in gastric specimens was determined by tissue qPCR and immunohistochemisty. A SGC-7901 cell line with low B7-H3 expression was established by lentiviral-mediated RNA interference to investigate the effect of B7-H3 on cancer cell migration and invasion in vitro. By establishing an orthotopic transplantation gastric cancer mouse model, the effect of B7-H3 on cell migration and invasion was studied in vivo. B7-H3 expression was significantly higher in the gastric cancer group than that in the normal gaster group. B7-H3 knockdown by RNA interference decreased cell migration and Transwell invasion up to 50% in vitro. In the orthotopic transplantation gastric cancer mouse model, the effect of inhibiting metastasis by knockdown of B7-H3 was assessed in terms of the average postmortem abdominal visceral metastatic tumor weight. The results revealed that inhibition of B7-H3 expression reduced gastric cancer metastasis in vivo. In conclusion, B7-H3 is aberrantly expressed in gastric cancer. In addition to modulating tumor immunity, B7-H3 may have a novel role in regulating SGC-7901 cell metastasis.

Butyrophilin molecules (commonly contracted to BTN), collectively take their name from the eponymous protein in cow's milk. They are considered to be members of the B7 family of costimulatory receptors, which includes B7.1 (CD80), B7.2 (CD86), and related molecules, such as PD-L1 (B7-H1, CD274), ICOS-L (CD275), and B7-H3 (CD276). These coreceptors modulate T cell responses upon antigen presentation by major histocompatibility complex and cognate αβ T cell receptor engagement. Molecules such as BTN3A1 (CD277), myelin oligodendrocyte glycoprotein, and mouse Skint1 and Btnl2, all members of the butyrophilin family, show greater structural and functional diversity than the canonical B7 receptors. Some butyrophilins mediate complex interactions between antigen-presenting cells and conventional αβ T cells, and others regulate the immune responses of specific γδ T cell subsets by mechanisms that have characteristics of both innate and adaptive immunity.

B7-H3, a member of the B7 family of immunoregulatory proteins, is overexpressed in cancer and promotes tumor growth, metastasis, and drug resistance. We discuss here the involvement of B7-H3 in cancer that goes beyond its immune regulatory function, and discuss the potential of B7-H3 as a biomarker and therapeutic target.

B7-H3 negatively regulates Th1-mediated immune responses. Here, we aimed to investigate whether B7-H3 is involved in the development of murine experimental allergic conjunctivitis (EC), which is predominantly mediated by Th2 cells. Intraperitoneal injection of anti-B7-H3 Ab during the induction phase of EC significantly augmented the severity of EC evaluated as conjunctival eosinophil numbers and Ag-induced IL-5 production by splenocytes. Injection of anti-B7-H3 Ab during the effector phase of EC did not significantly affect the severity of EC. In addition, transfer of Ag-primed splenocytes treated with anti-B7-H3 Ab in vitro did not significantly affect the severity of EC, compared to the splenocytes treated with the control Ab. Thus, regulation of EC by blocking of B7-H3 was observed during the induction phase but not the effector phase. Moreover, this study provides a new notion that B7-H3 regulates not only Th1-mediated but also Th2-mediated immune reactions.

Aberrant tumor cell expression of B7-H3, a member of the B7-family that stimulates interleukin-10 (IL-10) secretion, contributes to tumor immune evasion and tumor progression. The aim of this study was to investigate the expression of B7-H3 and IL-10 in ductal and lobular breast cancer tissues. Using immunohistochemistry, B7-H3 and IL-10 protein expression in tumor specimens of primary human breast cancer was investigated. The association between B7-H3 or IL-10 expression and clinicopathological variables was analyzed. The correlation between the expression of B7-H3 and IL-10 was also evaluated. In tumor tissues, the expression of B7-H3 and IL-10 was identified on the cell membrane and in the cytoplasm. Expression of B7-H3 was observed in 90.60% (106/117) of the specimens and 80.34% (94/117) expressed IL-10. Patients with a positive B7-H3 or high IL-10 expression were more likely to have positive lymph node metastasis (N1-3; P=0.018 or 0.035, respectively) and advanced disease (stage II-IV; P=0.011 or 0.039, respectively) compared to those with a negative or low expression. Furthermore, B7-H3 expression was correlated with IL-10 in tumor cells (R=0.545, P=0.000). High B7-H3 expression in human breast cancer tissues may be important in tumor progression and invasiveness. This expression appeared to be correlated with the ability of B7-H3 to promote IL-10 secretion.

Placental trophoblast cells form a cellular barrier between the potentially immunogenic fetus and maternal leukocytes. Trophoblasts subvert maternal immunity by producing surface-bound and soluble factors that interact with maternal leukocytes. Here, we describe the distribution of three members of the expanding family of B7 immunomodulatory molecules: B7-DC, B7-H2, and B7-H3. B7-DC and B7-H3 inhibit antigen-stimulated lymphocyte activation while B7-H2 serves in a regulatory capacity, often promoting a Th2 immunophenotype. First trimester and term placentas, purified trophoblast cells, choriocarcinoma cell lines, and human umbilical vein endothelial cells were analyzed for B7 family RNA and protein expression. Transcripts and proteins for all three B7s were present throughout gestation but were differentially expressed within the trophoblast and the stroma. Whereas B7-DC was prominent on the syncytiotrophoblast of early placenta, it was absent from the trophoblast at term. In contrast, B7-H2 and B7-H3 were prominent on the extravillous trophoblast throughout gestation. Lastly, stromal cells, including macrophages and endothelial cells, differentially expressed B7-DC, B7-H2, and B7-H3, depending on gestational age. Thus, all three of these newly discovered B7 proteins are differentially positioned at the maternal-fetal interface such that they could steer maternal leukocytes away from a harmful immune response and toward a favorable one.

OBJECTIVE

Compared with non-smoking counterparts, smoking-associated lung cancers have a higher mutational load, resulting in the creation of more tumor neoantigens and increased immunogenicity. B7-H3 (also known as CD276) belongs to a family of immune modulators that includes PD-1 and PD-L1 (also known as B7-H1 or CD274). Considering the evidence that PD-L1 inhibitors have been shown to be more effective against lung cancer in smokers, we herein examined the prognostic interaction of tumor B7-H3 expression level with smoking history in lung adenocarcinoma patients.

METHODS

Using tissue microarrays comprising 270 consecutive cases of lung adenocarcinoma, we evaluated tumor B7-H3 expression by immunohistochemistry. We examined the prognostic association between B7-H3 expression levels and smoking history, using Cox proportional hazards regression analysis and the log-rank test. Additionally, we used logistic regression analysis to examine the correlations between B7-H3 expression levels and clinicopathological/molecular features of lung adenocarcinoma.

RESULTS

The association of B7-H3 expression with survival differed by smoking history (Pinteraction=0.014); high B7-H3 expression was associated with decreased lung cancer-specific survival in moderate/heavy-smoking patients (smoking index [SI]≥400) (hazard ratio [HR]=3.07, 95% confidence interval [CI]=1.74-5.49, P=0.0001; log-rank: P<0.0001), but not in non/light-smoking patients (SI<400) (HR=1.14, 95% CI=0.63-1.96, P=0.64; log-rank: P=0.64). Interestingly, in moderate/heavy-smoking patients, high B7-H3 expression was associated with decreased survival in stage I cancer (log-rank; P=0.0005), whereas it showed no significant difference of survival in stage II-IV cancer (P=0.37). High B7-H3 expression was associated with smokers (univariable odds ratio [OR]=2.63, 95% CI=1.51-4.65; P=0.0005) and independently associated with EGFR wild-type status (multivariable OR=2.80, 95% CI=1.38-5.84; P=0.0042).

CONCLUSIONS

We demonstrated that the prognostic association of B7-H3 expression indeed differed according to smoking history. Our study also showed the significant association of high B7-H3 expression with EGFR wild-type and smoking patients, indicating the potential effectiveness of anti-B7-H3 therapy for EGFR wild-type or smokers' lung adenocarcinoma.

Neuroblastoma (NB) is the most common extra-cranial solid tumor of childhood and arises from developing sympathetic nervous system. Most primary tumors localize in the abdomen, the adrenal gland, or lumbar sympathetic ganglia. Amplification in tumor cells of MYCN, the major oncogenic driver, patients' age over 18 months, and the presence at diagnosis of a metastatic disease (stage IV, M) identify NB at high risk of treatment failure. Conventional therapies did not significantly improve the overall survival of these patients. Moreover, the limited landscape of somatic mutations detected in NB is hampering the development of novel pharmacological approaches. Major efforts aim to identify novel NB-associated surface molecules that activate immune responses and/or direct drugs to tumor cells and tumor-associated vessels. PVR (Poliovirus Receptor) and B7-H3 are promising targets, since they are expressed by most high-risk NB, are upregulated in tumor vasculature and are essential for tumor survival/invasiveness. PVR is a ligand of DNAM-1 activating receptor that triggers the cytolytic activity of natural killer (NK) cells against NB. In animal models, targeting of PVR with an attenuated oncolytic poliovirus induced tumor regression and elimination. Also B7-H3 was successfully targeted in preclinical studies and is now being tested in phase I/II clinical trials. B7-H3 down-regulates NK cytotoxicity, providing NB with a mechanism of escape from immune response. The immunosuppressive potential of NB can be enhanced by the release of soluble factors that impair NK cell function and/or recruitment. Among these, TGF-β1 modulates the cytotoxicity receptors and the chemokine receptor repertoire of NK cells. Here, we summarize the current knowledge on the main cell surface molecules and soluble mediators that modulate the function of NK cells in NB, considering the pros and cons that must be taken into account in the design of novel NK cell-based immunotherapeutic approaches.

BACKGROUND

In the tumor microenvironment, factors inhibiting the targeting of cancer cells by activated T cells have recently been noted. B7-H3 belongs to the B7 superfamily of immune regulatory ligands and plays an important role in the adaptive immune response of co-inhibitory/stimulatory factors in regulating T cells. However, the degree to which B7-H3 directly affects tumor immune evasion mechanisms remains unclear, particularly in patients with breast cancer. Regulatory T cells (Tregs) are known as a key player in the inhibition of immune mechanisms. The present study demonstrated that expression of B7-H3 on tumor cells and the number of Tregs in the tumor microenvironment independently affected prognosis in breast cancer patients.

METHODS

We immunohistochemically investigated the presence of B7-H3 and forkhead box P3 (Foxp3)-positive Tregs in pathological specimens from 90 patients with breast cancer.

RESULTS

Positive B7-H3 expression was associated with shorter recurrence-free survival (RFS) (p = 0.014). A higher percentage of Foxp3-positive cells also correlated with shorter RFS (p = 0.039). Multivariate analysis showed B7-H3 as an independent factor on RFS. Foxp3 expression in tumor-infiltrating lymphocytes (TILs) correlated significantly with larger tumor size (>2 cm), expression of human epidermal growth factor receptor 2 (HER2), and higher nuclear grade (p = 0.003, p < 0.001, p = 0.001, respectively). No correlation was identified between expression of B7-H3 and the percentage of Foxp3-positive TILs.

CONCLUSIONS

B7-H3 and Foxp3 can be regarded as markers of poor prognosis in breast cancer. These expressions were not correlated, suggesting that B7-H3 expression plays an independent role in tumor immune evasion, regardless of Tregs.

BACKGROUND

The purpose of this study was to validate B7-H3 as a new cancer-specific endothelial marker in clear cell renal cell carcinoma.

METHODS

B7-H3 expression patterns were compared between cancer and paired adjacent normal renal parenchyma by immunohistochemistry in paraffin-embedded specimens from 200 consecutive patients with clear cell renal cell carcinoma from January to December 2010. Four corpus luteum specimens were used as physiologic angiogenesis controls. B7-H3 messenger (m)RNA levels representing circulating endothelial cells were analyzed in 24 peripheral blood samples using real-time polymerase chain reaction. Collection and processing of tissue and peripheral blood samples was performed in compliance with the Declaration of Helsinki.

RESULTS

Cancer cell-specific expression of B7-H3 was detected in 19% of clear cell renal cell carcinoma specimens, and tumor vasculature B7-H3 expression was confirmed in 98% (196) of cases. A diffuse pattern of vascular B7-H3 expression was associated with multiple adverse clinical and pathologic features (P<0.001). B7-H3 expression was not detected in paired adjacent normal renal parenchyma or vessels, or in luteal blood vessels. The B7-H3 mRNA level of circulating endothelial cells in peripheral blood was significantly higher in metastatic clear cell renal cell carcinoma (P<0.001).

CONCLUSIONS

This pilot study indicates that B7-H3 is a cancer-specific endothelial marker of potential importance for the development of tumor-specific, vascular-targeted therapies, and is a prognostic marker in clear cell renal cell carcinoma.

B7-H3 (CD276), part of the B7 superfamily of immune checkpoint molecules, has been shown to have an immunomodulatory role. Its regulation, receptor and mechanism of action remain unclear. B7-H3 protein expression correlates with prostate cancer outcomes, and humanized monoclonal antibodies (that is, enoblituzumab) are currently being investigated for therapeutic use. Here we used genomic expression data to examine the relationship between B7-H3 mRNA expression and prostate cancer.

Prostatectomy tissue from 2781 patients were profiled using the Affymetrix HuEx 1.0 ST microarray. Pairwise comparisons were used to identify significant associations between B7-H3 expression and clinicopathologic variables, and survival analyses were used to evaluate the prognostic significance of B7-H3. Pearson's correlation analyses were performed to assess the relationship of B7-H3 expression with molecular subtypes and individual transcripts. Androgen receptor (AR) occupancy at the B7-H3 locus was determined using chromatin immunoprecipitation (ChIP), and androgen-dependent expression changes in B7-H3 was evaluated by quantitative reverse transcription PCR in LNCaP cell lines. Oncomine was queried to evaluate B7-H3 expression in metastatic disease.

B7-H3 mRNA expression was positively associated with higher Gleason score (P<0.001), tumor stage (P<0.001), and castrate resistant metastatic disease (P<0.0001). High B7-H3 expression correlated with the development of metastasis and prostate cancer specific mortality, but this was not significant on multi-variable analysis. B7-H3 expression correlated with ERG-positive disease (r=0.99) and AR expression (r=0.36). ChIP revealed an AR-binding site upstream of B7-H3, and the presence of androgens decreased B7-H3 expression in LNCaP suggesting potential direct AR regulation. Gene set enrichment analysis demonstrated an association of B7-H3 with androgen signaling as well as immune regulatory pathways.

Higher B7-H3 expression correlates with Gleason grade, prostate cancer stage and poor oncologic outcomes in prostatectomy cohorts. B7-H3 expression appears to be related to androgen signaling as well as the immune reactome.

B7-H3 is a member of the B7 family thought to be a co-regulatory factor of antigen-specific T-cell immune response via co-stimulatory and co-inhibitory receptors. We evaluated its potential expression in head and squamous cell carcinoma (SCC) cell lines, and in clinical tissue samples obtained from 37 patients with human hypopharyngeal SCC. All head and neck SCC cell lines tested expressed both the B7-H3 gene and cell surface protein. The staining intensity of immunoreactivity by tumor cells was blindly evaluated by two head and neck surgeons and the results were categorized into 4 grades according to staining intensity. Eighty-seven percent of patients expressed B7-H3. B7-H3 expression was inversely correlated with the number of tumor infiltrating CD8+ T-cells (r=-0.4339, p=0.023). Patients who developed distant metastasis after tumor-free periods showed significantly higher B7-H3 expression scores compared to patients who did not develop distant metastasis during follow-up periods (p=0.048). Distant metastasis control ratio in patients with strong B7-H3 expression was significantly lower compared to that in patients with no to intermediate B7-H3 expression (p=0.040). Cause-specific survival ratio in patients with strong B7-H3 expression was significantly lower compared to that in patients with no to intermediate B7-H3 expression (p=0.028). Moreover, multivariate analysis revealed that strong B7-H3 expression was an independent prognostic factor in tumor-specific death in hypopharyngeal SCC (hazard ratio: 9.803, confidence interval: 0.018-0.539, p=0.0110).

Adoptive cellular immunotherapy has been proposed as an additional treatment of medulloblastoma, an intracranial tumor characterized by a particularly poor prognosis. However, little is known on the ability of the immune system to effectively attack this tumor. In this study, we show that activated human NK cells efficiently kill medulloblastoma cell lines in vitro. NK-mediated killing involved different activating receptors (including NKp46, NKp30, DNAM-1 and NKG2D) and correlated with the presence of their specific ligands on tumor cells. In contrast, the absence of major adhesion interactions, such as LFA-1/ICAM did not impair the NK-mediated cytotoxicity. Medulloblastoma expressed a number of tumor-associated molecules including CD146 and CD133, considered a marker for cancer stem cells. Remarkably, both CD133-positive and CD133-negative cell lines were susceptible to lysis. Tumor cells also expressed molecules that are currently used as diagnostic tools for neuroblastoma cell identification. In particular, B7 homolog 3 (B7-H3) was expressed by all the medulloblastoma cell lines analyzed, while the presence of GD(2) and NB84 was restricted to given cell lines and/or marked a defined tumor cell subset.

B7-H3, first recognized as a co-stimulatory molecule, is abnormally expressed in cancer tissues and is associated with cancer metastasis and a poor prognosis. However, as an initial event of metastasis, the relationship between the Epithelial-Mesenchymal Transition (EMT ) in cancer cells and B7-H3 has still not been investigated. In this study, we first analyzed B7-H3 expression by immunohistochemistry in colorectal cancer tissues. B7-H3 was expressed in the cancer cell membrane and was associated with the T stage of colorectal cancer; it also showed a positive correlation with MMP2 and MMP9 expression in cancer tissues. Over-expression of B7-H3 in SW480 cells allowed cancer cells to invade and metastasize more than the control cells, whereas invasion and metastasis capabilities were decreased after B7-H3 was knocked down in Caco-2 cells. We further showed that B7-H3 down-regulated the expression of E-cadherin and β-catenin and up-regulated N-cadherin and Vimentin expression, implying that B7-H3 promoted the EMT in colorectal cancer cells. We also checked another character of the EMT, the stemness of cancer cells. CD133, CD44 and Oct4 were significantly elevated after the SW480 cells were transfected with B7-H3 and reduced in Caco-2 cells after B7-H3 was inhibited. In subsequent studies, we proved that B7-H3 upregulated the expression of Smad1 via PI3K-Akt. In conclusion, B7-H3 promotes the EMT in colorectal cancer cells by activating the PI3K-Akt pathway and upregulating the expression of Smad1.

B7 family proteins are important immune response regulators, and can mediate oncogenic signaling and cancer development. We have used human triple-negative breast cancer cell lines with different expression levels of B7-H3 to evaluate its effects on the sensitivity to 22 different anticancer compounds in a drug screen. API-2 (triciribidine) and everolimus (RAD-001), two inhibitors that target the PI3K/AKT/mTOR pathway, showed enhanced inhibition of cell viability and proliferation in B7-H3 knockdown tumor cells compared to their B7-H3 expressing counterparts. Similar inhibition was seen in control cells treated with an anti-B7-H3 monoclonal antibody. In B7-H3 overexpressing cells, the effects of the two drugs were reduced, supported also by in vivo experiments in which B7-H3 overexpressing xenografts were less sensitive to everolimus than control tumors. In API-2 and everolimus-treated B7-H3 overexpressing cells, phospho-mTOR levels were decreased. However, phosphorylation of p70S6K was differentially regulated in B7-H3 cells treated with API-2 or everolimus, suggesting a different B7-H3-mediated mechanism downstream of mTOR. Both API-2 and everolimus decreased the glycolysis of the cells, whereas knockdown of B7-H3 decreased and B7-H3 overexpression increased the glycolytic capacity. In conclusion, we have unveiled a previously unknown relationship between B7-H3 expression and glycolytic capacity in tumor cells, and found that B7-H3 confers resistance to API-2 and everolimus. The results provide novel insights into the function of B7-H3 in cancer, and suggest that targeting of B7-H3 may be a novel alternative to improve current anticancer therapies.

Transforming growth factor-beta 1 (TGF-β1) suppresses T cell function, promoting tumor immune escape. Yet, whether the depression of TGF-β1 on T cell function is mediated by co-inhibitory molecules B7-H3 and B7-H4 remains largely unclear. Here, we demonstrated that TGF-β1 elevated the expression of miR-155 in colorectal cancer cells through SMAD3 and SMAD4. The upregulated miR-155 attenuated miR-143 by inhibiting its direct target, the transcription factor CEBPB. Consequently, the direct target genes of miR-143, B7-H3 and B7-H4, were augmented in the cytoplasm and membrane of tumor cells. Over-expression of B7-H3 and B7-H4 in HCT-116 cells induced T cells to secrete TGF-β1 and the immunosuppressive cytokines IL-2, IL-6, and IL-17. Restoration of miR-143 inhibited the growth of HCT-116 xenograft tumors in mice, and also repressed the expression of B7-H3 and B7-H4 in the tumors. Thus, this study reveals the mechanism by which TGF-β1 leads to T cell-mediated tumor evasion through an increase in B7-H3 and B7-H4 expression.

B7‑H3, a newly identified co‑stimulatory molecule, has been reported to be highly expressed in a number of types of cancer and is associated with a poor prognosis. Transwell experiments and a wound-healing assay were used to detect the role of over‑expressed B7‑H3 on cell migration and invasion in colorectal cancer (CRC) cells. The expression level of matrix metallopeptidase 9 (MMP‑9) was further investigated by zymography experiments and western blot analysis, and involvement of the Janus kinase 2 (Jak2) signal transducer and activator of transcription 3 (STAT3) signaling pathway was determined using AG490, a Jak2 selective inhibitor. Data showed that overexpression of B7‑H3 promoted cell migration and invasion in CRC. Further investigation certified that enhanced expression of B7‑H3 elevated MMP‑9 through upregulation of the Jak2‑Stat3 signaling pathway. Due to its pro‑migratory and pro‑invasive function, B7‑H3 may serve as a therapeutic target in the treatment of CRC.

BACKGROUND

Human Ig-like transcript 4 (ILT-4) is a member of the inhibitory receptor family for immune function. Little is known about the expression levels of ILT-4 in tumor cells.

METHODS

We have studied the expression levels of ILT-4 both in vitro in cancer cell lines and in vivo in tumor tissues from 70 patients with non-small cell lung cancer (NSCLC) by reverse transcriptase-polymerase chain reaction, fluorescence-activated cell sorting, and immunohistochemical analysis.

RESULTS

Three cancer cell lines (H1299, A549, and U1810) express ILT-4 messenger RNA, and only two cell lines (H1299 and A549) express ILT-4 protein on the cell surface. Approximately 37.1% of 70 tumor tissue samples express ILT-4, which is localized in the cell membrane and cytoplasm. In addition, tumor cells and stromal and plasma cells also express ILT-4. The number of infiltrating lymphoid cells in the tumor tissues that express B7-H3 was much lower than those that did not, but there is no significant correlation between ILT-4 expression and disease progression including nodal metastasis.

CONCLUSIONS

These findings suggest that ILT-4 is frequently expressed in both tumor and stromal cells of NSCLC, and it might play an important role in regulation of the host immune system.

In humans and mice naturally occurring regulatory T cells (nTregs) are crucial for the maintenance of peripheral tolerance by controlling not only potentially autoreactive T cells but virtually all cells of the adaptive and innate immune system. Here we show that co-culture of murine dendritic cells (DC) and nTregs results in an immediate increase of cAMP in DC, responsible for a rapid down-regulation of co-stimulatory molecules (CD80, CD86). In addition, the inhibitory surface molecule B7-H3 on DC is up-regulated. Subsequently, nTreg-derived IL-10 inhibits the cytokine production (IL-6, IL-12) of suppressed DC therewith preserving their silent phenotype. Hence, our data indicate that nTregs effectively control exuberant immune responses by directly limiting the stimulatory capacity of DC via a sophisticated chronologic action of inhibitory signals.

T cells play critical roles in anti-tumor immunity. Up-regulation of immune checkpoint molecules (PD-1, PD-L1, CTLA-4, TIM-3, Lag-3, TIGIT, CD73, VISTA, B7-H3) in the tumor microenvironment is an important mechanism that restrains effector T cells from the anti-tumor activity. To date, immune checkpoint antibodies have demonstrated significant clinical benefits for cancer patients treated with mono- or combination immunotherapies. However, many tumors do not respond to the treatment well, and merely blocking the immune suppression pathways by checkpoint-regulatory antibodies may not render optimal tumor growth inhibition. Binding of the antibody Fc-hinge region to Fc gamma receptors (FcγRs) has been shown to exert a profound impact on antibody function and in vivo efficacy. Investigation of immune checkpoint antibodies regarding their effector functions and impact on therapeutic efficacy has gained more attention in recent years. In this review, we discuss Fc variants of antibodies against immune checkpoint targets and the potential mechanisms of how FcγR-binding could influence the anti-tumor activity of these antibodies.

Anti-angiogenic therapy has been successfully applied to treat colorectal cancer (CRC). Ginsenoside Rg3, derived from the Chinese herb ginseng, has anti-vascularization effects and can inhibit tumor growth and metastasis, and can sensitize cancer cells to chemotherapy. Therefore, in the present study, we investigated whether Rg3 could be appropriate for CRC treatment. Growth of CRC cells was assessed by an MTT (methyl thiazolyl tetrazolium) assay in vitro and using orthotopic xenograft models in vivo. mRNA expression was evaluated using real-time PCR. Protein levels were tested by western blotting, flow cytometry and immunohistochemistry. Migration was determined using a wound-healing assay. Stemness was further confirmed using a plate clone formation assay. We found that Rg3 repressed the growth and stemness of CRC cells both in vitro and in vivo. Rg3 also impaired the migration of CRC cells in vitro. Rg3 downregulated the expressions of angiogenesis-related genes, and repressed the vascularization of CRC xenografts. In addition, Rg3 strengthened the cytotoxicity of 5-Fluorouracil and oxaliplatin against orthotopic xenografts in vivo. Moreover, Rg3 downregulated the expressions of B7-H1 and B7-H3, high expressions of which were associated with reduced overall survival (OS) of CRC patients. Hence, Rg3 not only repressed the growth and stemness of CRC cells, but could also remodel the tumor microenvironment through repressing angiogenesis and promoting antitumor immunity. Therefore, Rg3 could be a novel therapeutic for the CRC treatment.

Renal cell carcinoma (RCC) is an immunogenic and proangiogenic cancer. Although antivascular endothelial growth factor (VEGF) therapies achieve impressive responses in some patients, many tumors eventually develop resistance to such therapy. The B7 family molecules such as CTLA-4, PD-1, and PD-L1 are pivotal players in immune checkpoints that positively or negatively regulate various immune responses. Recently, immunotherapy based on blocking immune checkpoints with anti-CTLA4, anti-PD-1, or anti-PD-L1 antibodies has been proposed as a potential new approach to the treatment of metastatic RCC. Higher expression of PD-L1 and B7-H4 in the tumors is associated with a poor prognosis in RCCs, however, the clinical impact of serum levels of B7 family molecules has not been elucidated in patients with metastatic RCCs receiving VEGF-targeted agents. We assessed the preoperative serum levels of B7 family molecules, including CD80, CD86, PD-1, PD-L1, B7-H3, B7-H4, and CTLA-4, and CD28 in RCC patients, and determined their relations with various clinicopathological characteristics. Elevated preoperative serum levels of PD-L1 and B7-H4 were correlated with less differentiated tumors, higher invasive and metastatic potential, a worse response to anti-VEGF therapy, and shorter overall survival. These findings suggested that investigating preoperative serum levels of PD-L1 and B7-H4 might not only be useful to assess the biological aggressiveness of RCCs, but also to predict the efficacy of anti-VEGF therapy and the eventual prognosis, indicating the future design of clinical trials of therapies targeting immune checkpoint in advanced RCCs.

Current cancer gene therapies aim at the induction of systemic antitumor immune responses. Tumors may deliver antigens to T-cells, but may lack the costimulatory signals necessary for mounting an effective response. The purpose of this study was to evaluate the efficacy of an adenoviral delivery of the <em>B7</em>-<em>H3</em> costimulatory molecule in mice to induce antitumor immune responses. Colon cancers were established by orthotopic injection of syngeneic colon cancer cells into the cecum on Balb/c mice. After two weeks, these mice were treated by intratumoral injection of an adenovirus expressing mouse <em>B7</em>-<em>H3</em> (Ad-<em>B7</em>-<em>H3</em>-GFP) or a control virus (Ad-GFP). Ad-<em>B7</em>-<em>H3</em>-GFP treatment resulted in a reduction of tumor size compared to the controls. In addition, the occurrence of secondary metastasis was significantly reduced in <em>B7</em>-<em>H3</em> treated mice compared to control animals (lymph node 7/10 vs. 10/10; liver 2/10 vs. 8/10, p<or=0.05). Ad-<em>B7</em>-<em>H3</em>-GFP treated animals showed significantly higher frequencies of tumor-specific interferon-gamma producing CD8+ T-cells (p<or=0.05) and higher interleukin-12 levels (p<or=0.01) than control animals. This study demonstrates that adenoviral <em>B7</em>-<em>H3</em> transfer is able to induce a specific cellular antitumor immune response leading to primary tumor regression and reduction of secondary metastasis in vivo.