High blood levels of soluble OX40 (CD134), an immune costimulatory molecule, indicate reduced survival in patients with advanced colorectal cancer.

The interaction between tumor necrosis factor receptor superfamily, member 4 (OX40) on T cells and the OX40 ligand (OX40L) on antigen­presenting cells (APCs) is a pivotal step for T­cell activation and the promotion of antitumor immunity. However, it is hypothesized that soluble OX40 (sOX40) in blood suppresses T­cell activation by blocking the OX40/OX40L interaction. In the present study, the association between blood sOX40 levels and the clinical characteristics of advanced colorectal cancer (CRC) patients was investigated. Blood was collected from 22 patients with advanced CRC. Blood sOX40 levels were determined by enzyme­linked immunosorbent assay (ELISA). Messenger RNA (mRNA) expression encoding OX40 or cytokines was analyzed by quantitative RT­PCR. Blood sOX40 levels were positively correlated with the blood levels of carbohydrate antigen (CA) 19­9, carcinoembryonic antigen (CEA), C­reactive protein (CRP) and soluble programmed cell death ligand­1 (PD­L1) in patients but negatively correlated with the blood levels of albumin. Blood sOX40 levels were not correlated with the mRNA expression of interferon (IFN)­gamma, interleukin (IL)­6, IL­10 and IL­4 in the peripheral blood mononuclear cells (PBMCs) of the patients and were not correlated with the frequency of programmed cell death­1 (PD­1) expressing CD4+, CD8+ and CD56+ cells. Notably, according to both univariate and multivariate analyses, high blood sOX40 levels were significantly correlated with a reduced survival time in patients. Although activated Jurkat cells (a human T cell line) exhibited an upregulation of sOX40 production and OX40 mRNA expression, the OX40 mRNA expression of the PBMCs of patients was not correlated with blood sOX40 levels. High blood levels of sOX40 were correlated with a reduced survival time in patients with advanced CRC, possibly associated with the suppression of antitumor immunity by sOX40.

Claudin 7 as a possible novel molecular target for the treatment of pancreatic cancer.

BACKGROUND/OBJECTIVES: Pancreatic cancer consists of various subpopulations of cells, some of which have aggressive proliferative properties. The molecules responsible for the aggressive proliferation of pancreatic cancer may become molecular targets for the therapies against pancreatic cancer. METHODS: From a human pancreatic cancer cell line, MIA PaCa-2, MIA PaCa-2-A cells with an epithelial morphology and MIA PaCa-2-R cells with a non-epithelial morphology were clonogenically isolated by the limiting dilution method. Gene expression of these subpopulations was analyzed by DNA microarray. Gene knockdown was performed using siRNA. RESULTS: Although the MIA PaCa-2-A and MIA PaCa-2-R cells displayed the same DNA short tandem repeat (STR) pattern identical to that of the parental MIA PaCa-2 cells, the MIA PaCa-2-A cells were more proliferative than the MIA PaCa-2-R cells both in culture and in tumor xenografts generated in immunodeficient mice. Furthermore, the MIA PaCa-2-A cells were more resistant to gemcitabine than the MIA PaCa-2-R cells. DNA microarray analysis revealed a high expression of claudin (CLDN) 7 in the MIA PaCa-2-A cells, as opposed to a low expression in the MIA PaCa-2-R cells. The knockdown of CLDN7 in the MIA PaCa-2-A cells induced a marked inhibition of proliferation. The MIA PaCa-2-A cells in which CLDN7 was knocked down exhibited a decreased expression of phosphorylated extracellular signal-regulated kinase (p-Erk)1/2 and G1 cell cycle arrest. CONCLUSIONS: CLDN7 may be expressed in the rapidly proliferating and dominant cell population in human pancreatic cancer tissues and may be a novel molecular target for the treatment of pancreatic cancer.

Soluble Programmed Cell Death Ligand 1 as a Novel Biomarker for Nivolumab Therapy for Non-Small-cell Lung Cancer.

BACKGROUND: Biomarkers for predicting the effect of anti-programmed cell death 1 (PD-1) monoclonal antibody against non-small-cell lung cancer (NSCLC) are urgently required. Although it is known that the blood levels of soluble programmed cell death ligand 1 (sPD-L1) are elevated in various malignancies, the nature of sPD-L1 has not been thoroughly elucidated. We investigated the significance of plasma sPD-L1 levels as a biomarker for anti-PD-1 monoclonal antibody, nivolumab therapy. PATIENTS AND METHODS: The present prospective study included 39 NSCLC patients. The patients were treated with nivolumab at the dose of 3 mg/kg every 2 weeks, and the effects of nivolumab on NSCLC were assessed according to the change in tumor size, time to treatment failure (TTF), and overall survival (OS). The baseline plasma sPD-L1 concentration was determined using an enzyme-linked immunosorbent assay. RESULTS: The area under the curve of the receiver operating characteristic curve was 0.761. The calculated optimal cutoff point for sPD-L1 in the plasma samples was 3.357 ng/mL. Of the 39 patients, 59% with low plasma sPD-L1 levels achieved a complete response or partial response and 25% of those with high plasma sPD-L1 levels did so. In addition, 22% of the patients with low plasma sPD-L1 levels developed progressive disease compared with 75% of those with high plasma sPD-L1 levels. The TTF and OS were significantly longer for those patients with low plasma sPD-L1 levels compared with the TTF and OS for those with high plasma sPD-L1 levels. CONCLUSION: The clinical benefit from nivolumab therapy was significantly associated with the baseline plasma sPD-L1 levels. Plasma sPD-L1 levels might represent a novel biomarker for the prediction of the efficacy of nivolumab therapy against NSCLC.

Nafamostat mesilate, a serine protease inhibitor, suppresses interferon-gamma-induced up-regulation of programmed cell death ligand 1 in human cancer cells.

Programmed cell death ligand-1 (PD-L1) plays a pivotal role in the suppression of antitumour immunity by binding to programmed cell death-1 (PD-1) on tumouricidal cytotoxic T lymphocytes (CTLs), rendering them inactive. As blockade of PD-1/PD-L1 interaction by the monoclonal antibodies induced effective T cell-mediated antitumour response, suppression of PD-L1 expression in tumour cells by the chemical agent might contribute to treatment against malignant tumours. Nafamostat mesilate (NM), a serine protease inhibitor that is frequently used in the clinic, potently suppressed interferon-gamma (IFN-gamma)-induced up-regulation of PD-L1 in cultured human lung cancer cells (HLC-1) at both the messenger RNA (mRNA) and protein levels. Interestingly, suppression of IFN-gamma-induced up-regulation of human leukocyte antigen (HLA)-ABC by NM was limited, suggesting that NM did not block CTL responses to tumour cells. NM treatment did not affect the activation status of signal transducer and activator of transcription (STAT) 1 or the induction of interferon regulatory factor (IRF)-1 expression in IFN-gamma-treated HLC-1 cells. Although NM treatment promoted the phosphorylation of extracellular signal-regulated kinases (Erk) 1/2, an Erk inhibitor, U0126, could not reverse the suppression of PD-L1 up-regulation by IFN-gamma. Suppression of IFN-gamma-induced up-regulation of PD-L1 by NM was not associated with the inhibition of nuclear factor kappa B (NF-kB) or protease-activated receptor (PAR)-1 pathway. Besides HLC-1 cells, NM suppressed IFN-gamma-induced PD-L1 up-regulation in three human pancreatic cancer cell lines. NM could potentiate the antitumour effect of cancer vaccines or immune checkpoint inhibitors by preventing IFN-gamma-induced PD-L1 up-regulation and blocking immune checkpoint suppression.

High plasma levels of soluble programmed cell death ligand 1 are prognostic for reduced survival in advanced lung cancer.

OBJECTIVES: Programmed cell death-ligand 1 (PD-L1) expressed in tumor tissues is a key molecule for immune suppression, given its role in immune checkpoints. The significance and implication of soluble PD-L1 (sPD-L1) in the blood of lung cancer patients remain unknown. PATIENTS AND METHODS: Blood samples were prospectively collected from patients with advanced lung cancer, and the plasma sPD-L1 concentrations were measured by enzyme-linked immunosorbent assay. The correlations of the plasma sPD-L1 levels with clinico-pathological status, laboratory data, and survival of the patients were analyzed. RESULTS: Ninety-six patients with advanced lung cancer were analyzed, including 73 with adenocarcinoma, 12 with squamous cell carcinoma, and seven with small-cell lung cancer. Sixty-five were naïve to chemotherapy, and 20 had received two or more lines of chemotherapy. The mean plasma sPD-L1 concentration of all the patients was 6.95±2.90ng/ml (range 2.30-20.0ng/ml), and this value is significantly increased compared with that previously reported for normal subjects. No correlation of the plasma sPD-L1 level with histological subtypes, adenocarcinoma genetic status, smoking history, clinical stage or laboratory data was found. However, overall survival was significantly reduced in patients with high (≥7.32ng/ml) compared with low (<7.32ng/ml) plasma sPD-L1 levels (13.0 vs. 20.4 months, p=0.037). Multivariate analysis revealed that high sPD-L1 levels were significantly related to poor prognosis (hazard ratio 1.99, p=0.041). CONCLUSION: High plasma sPD-L1 levels were associated with poor prognosis in patients with advanced lung cancer, possibly associated with suppression of anti-tumor immunity. Clinical trial register and their clinical registration number: UMIN%000014760.

Vaccination with vascular progenitor cells derived from induced pluripotent stem cells elicits antitumor immunity targeting vascular and tumor cells.

Vaccination of BALB/c mice with dendritic cells (DCs) loaded with the lysate of induced vascular progenitor (iVP) cells derived from murine-induced pluripotent stem (iPS) cells significantly suppressed the tumor of CMS-4 fibrosarcomas and prolonged the survival of CMS-4-inoculated mice. This prophylactic antitumor activity was more potent than that of immunization with DCs loaded with iPS cells or CMS-4 tumor cells. Tumors developed slowly in mice vaccinated with DCs loaded with iVP cells (DC/iVP) and exhibited a limited vascular bed. Immunohistochemistry and a tomato-lectin perfusion study demonstrated that the tumors that developed in the iVP-immunized mice showed a marked decrease in tumor vasculature. Immunization with DC/iVP induced a potent suppressive effect on vascular-rich CMS-4 tumors, a weaker effect on BNL tumors with moderate vasculature, and nearly no effect on C26 tumors with poor vasculature. Treatment of DC/iVP-immunized mice with a monoclonal antibody against CD4 or CD8, but not anti-asialo GM1, inhibited the antitumor activity. CD8(+) T cells from DC/iVP-vaccinated mice showed significant cytotoxic activity against murine endothelial cells and CMS-4 cells, whereas CD8(+) T cells from DC/iPS-vaccinated mice did not. DNA microarray analysis showed that the products of 29 vasculature-associated genes shared between genes upregulated by differentiation from iPS cells into iVP cells and genes shared by iVP cells and isolated Flk-1(+) vascular cells in CMS-4 tumor tissue might be possible targets in the immune response. These results suggest that iVP cells from iPS cells could be used as a cancer vaccine targeting tumor vascular cells and tumor cells.

Gemcitabine enhances Wilms' tumor gene WT1 expression and sensitizes human pancreatic cancer cells with WT1-specific T-cell-mediated antitumor immune response.

Wilms' tumor gene (WT1), which is expressed in human pancreatic cancer (PC), is a unique tumor antigen recognized by T-cell-mediated antitumor immune response. Gemcitabine (GEM), a standard therapeutic drug for PC, was examined for the regulation of WT1 expression and the sensitizing effect on PC cells with WT1-specific antitumor immune response. Expression of WT1 was examined by quantitative PCR, immunoblot analysis, and confocal microscopy. Antigenic peptide of WT1 presented on HLA class I molecules was detected by mass spectrometry. WT1-specific T-cell receptor gene-transduced human T cells were used as effecter T cells for the analysis of cytotoxic activity. GEM treatment of human MIAPaCa2 PC cells enhanced WT1 mRNA levels, and this increase is associated with nuclear factor kappa B activation. Tumor tissue from GEM-treated MIAPaCa2-bearing SCID mice also showed an increase in WT1 mRNA. Some human PC cell lines other than MIAPaCa2 showed up-regulation of WT1 mRNA levels following GEM treatment. GEM treatment shifted WT1 protein from the nucleus to the cytoplasm, which may promote proteasomal processing of WT1 protein and generation of antigenic peptide. In fact, presentation of HLA-A*2402-restricted antigenic peptide of WT1 (CMTWNQMNL) increased in GEM-treated MIAPaCa2 cells relative to untreated cells. WT1-specific cytotoxic T cells killed MIAPaCa2 cells treated with an optimal dose of GEM more efficiently than untreated MIAPaCa2 cells. GEM enhanced WT1 expression in human PC cells and sensitized PC cells with WT1-specific T-cell-mediated antitumor immune response.

The identification of a novel Paneth cell-associated antigen in a familial adenomatous polyposis mouse model.

Wnt signaling is important for the differentiation of the Paneth cell lineage in the small intestine. However, abnormal Wnt signaling predisposes to intestinal tumorigenesis in the familial adenomatous polyposis (FAP) mouse model. Vaccination with dendritic cells fused with tumor cells from FAP mice, in which Wnt signaling is constitutively activated, induced humoral immunity and suppressed intestinal tumor development. We identified the novel antigen Apa1 (Adenomatous polyposis antigen 1) recognized by antibodies in vaccinated mouse serum. Apa1 was localized in the Paneth cell-like tumor cells showing cytoplasmic ß-catenin accumulation and also in normal Paneth cells at the bottom of the crypts. Phospholipase A2 (Pla2g2a), known to act as an anti-bacterial agent and a major suppressor of intestinal tumors, was also expressed in the Paneth cells. These results suggest that Apa1 might be involved in anti-microbial defense and could influence tumor development in FAP mice via modulation of commensal microbiota.

Combined treatment with dendritic cells and 5-fluorouracil elicits augmented NK cell-mediated antitumor activity through the tumor necrosis factor-alpha pathway.

Antitumor effects and mechanism of combined therapy with a dendritic cell (DC) vaccine and fluorouracil (5-FU) were investigated. Cytotoxic activity against MC38 cells, untreated or pretreated with 5-FU, was examined in splenocytes from mice inoculated with DCs: DCs pulsed with MC38 lysate or treated with LPS or both and untreated DCs. Inoculation with all types of DCs induced the significant cytotoxic activity of splenocytes, and pretreatment of MC38 cells with 5-FU significantly enhanced the cytotoxic activity of splenocytes. Depletion of natural killer (NK) cells, but not of CD8 or CD4 T cells, in the splenocytes from DC (without MC38 lysate-pulse or LPS treatment thereafter)-inoculated mice decreased the cytotoxic activity. The cytotoxic effect was eliminated by treatment with a monoclonal antibody (mAb) against tumor necrosis factor (TNF)-alpha and was partially inhibited by concanamycin A. Inoculation of mice with DCs upregulated TNFalpha expression on NK cells. MC38 cells pretreated with 5-FU exhibited enhanced expression of procaspase 8 and efficiently underwent apoptosis by TNF-alpha with activation of caspase 8. Although treatment with 5-FU upregulated Rae-1 expression on MC38 cells, the NK-cell-mediated cytotoxic activity was not suppressed by treatment with an anti-Rae-1 mAb or an antinatural killer group 2D mAb or both. These results indicate that combined therapy with a DC vaccine and 5-FU is a promising strategy for cancer treatment mediated by the tumoricidal activity of NK cells through the TNF-alpha pathway.

Dendritic/pancreatic carcinoma fusions for clinical use: Comparative functional analysis of healthy- versus patient-derived fusions.

Fetal calf serum (FCS)-independent pancreatic cancer cells were established in plasma protein fraction (PPF)-supplemented medium that is an agent of good manufacturing practice (GMP) grade. Dendritic cells (DCs) were activated with the Toll-like receptor agonist, penicillin-inactivated Streptococcus pyogenes (OK-432) that is also a GMP grade agent. Therefore, sufficient amounts of FCS-independent fusions were successfully generated with decreased potential hazards of FCS. The FCS-independent fusions expressed tumor-associated antigens, HLA-DR, costimulatory molecules, IL-12, and IL-10. Stimulation of T cells with fusions from healthy donors resulted in proliferation of T cells with high expression levels of perforin/granzyme B and IFN-gamma and efficient induction of antigen-specific cytotoxic T lymphocytes (CTLs). Selection and expansion of T-cell clones were confirmed by TCR Vbeta analysis. However, fusions from patients with metastatic pancreatic cancer induced increased expression levels of TGF-beta1 in CD4+ CD25high T cells and low levels of CTLs with decreased IFN-gamma production.

In vitro generation of cytotoxic and regulatory T cells by fusions of human dendritic cells and hepatocellular carcinoma cells.

BACKGROUND: Human hepatocellular carcinoma (HCC) cells express WT1 and/or carcinoembryonic antigen (CEA) as potential targets for the induction of antitumor immunity. In this study, generation of cytotoxic T lymphocytes (CTL) and regulatory T cells (Treg) by fusions of dendritic cells (DCs) and HCC cells was examined. METHODS: HCC cells were fused to DCs either from healthy donors or the HCC patient and investigated whether supernatants derived from the HCC cell culture (HCCsp) influenced on the function of DCs/HCC fusion cells (FCs) and generation of CTL and Treg. RESULTS: FCs coexpressed the HCC cells-derived WT1 and CEA antigens and DCs-derived MHC class II and costimulatory molecules. In addition, FCs were effective in activating CD4+ and CD8+ T cells able to produce IFN-gamma and inducing cytolysis of autologous tumor or semiallogeneic targets by a MHC class I-restricted mechanism. However, HCCsp induced functional impairment of DCs as demonstrated by the down-regulation of MHC class I and II, CD80, CD86, and CD83 molecules. Moreover, the HCCsp-exposed DCs failed to undergo full maturation upon stimulation with the Toll-like receptor 4 agonist penicillin-inactivated Streptococcus pyogenes. Interestingly, fusions of immature DCs generated in the presence of HCCsp and allogeneic HCC cells promoted the generation of CD4+ CD25high Foxp3+ Treg and inhibited CTL induction in the presence of HCCsp. Importantly, up-regulation of MHC class II, CD80, and CD83 on DCs was observed in the patient with advanced HCC after vaccination with autologous FCs. In addition, the FCs induced WT1- and CEA-specific CTL that were able to produce high levels of IFN-gamma. CONCLUSION: The current study is one of the first demonstrating the induction of antigen-specific CTL and the generation of Treg by fusions of DCs and HCC cells. The local tumor-related factors may favor the generation of Treg through the inhibition of DCs maturation; however, fusion cell vaccination results in recovery of the DCs function and induction of antigen-specific CTL responses in vitro. The present study may shed new light about the mechanisms responsible for the generation of CTL and Treg by FCs.

Mechanism of antitumor effect on mouse hepatocellular carcinoma by intratumoral injection of OK-432, a streptococcal preparation.

Intratumoral (i.t.) injection of OK-432, a streptococcal preparation, into implanted tumors of mouse hepatocellular carcinoma (MIH-2) showed antitumor effect including tumor eradication. Intraperitoneal administration of same dose OK-432 did not exhibit tumor suppressive effect. In vitro cytotoxic test suggested that direct cytotoxic effect of OK-432 was not associated with antitumor activity by i.t.-OK-432 treatment. It was also found that Toll-like receptor 4 signaling was not involved in i.t.-OK-432 treatment. Three mice out of five, which had shown tumor eradication by i.t.-OK-432 treatment did not reject re-challenge of MIH-2 cells. Splenocytes from i.t.-OK-432 treated mice did not produce IFN-gamma by stimulation with MIH-2 cells in vitro, but produced abundant IFN-gamma by stimulation with OK-432. Immunofluorescence microscopy demonstrated that CD4+T cells, but not CD8+T cells, infiltrated to i.t.-OK-432 treated tumor tissue produced IFN-gamma. Tumor-infiltrating CD4+T cells from i.t.-OK-432 treated tumor tissue produced IFN-gamma by in vitro stimulation with OK-432 higher than those from untreated tumor tissue. IFN-gamma directly induced apoptosis of MIH-2 cells in vitro. Collectively, i.t.-OK-432 treatment induced priming of CD4+T cells to antigenecity of OK-432, and repetitive i.t.-OK-432 treatment induced IFN-gamma production from OK-432-sensitized CD4+T cells in tumor site, leading to apoptosis of MIH-2 cells susceptible to IFN-gamma.

Antitumour activity mediated by CD4+ cytotoxic T lymphocytes against MHC class II-negative mouse hepatocellular carcinoma induced by dendritic cell vaccine and interleukin-12.

When BALA/c mice with BNL hepatocellular carcinoma (HCC) were treated with dendritic cells fused with BNL cells (DC/BNL) and recombinant murine interleukin (IL)-12, tumour development was significantly suppressed, whereas treatment with either DC/BNL or IL-12 alone did not show a tumour-suppressive effect. Antitumour activity induced by DC/BNL + IL-12 was abrogated by depletion of CD4+ T cells, but not by depletion of CD8+ T cells or natural killer cells. Splenic CD4+ T cells and CD8+ T cells from DC/BNL-treated mice showed cytotoxic activity against BNL cells after 3 days of incubation with DC/BNL, although BNL cells do not express major histocompatibility complex (MHC) class II molecules even after treatment with interferon (INF)-gamma. Furthermore, CD4+ T cells killed syngeneic-irrelevant CT26 cells and even allogeneic Hepa1-6 cells. This cytotoxicity was blocked by concanamycin A, but not by an anti-Fas ligand (FasL) monoclonal antibody, indicating that cytotoxic activity was mediated by perforin. Immunofluorescence microscopy demonstrated that abundant CD4+ T cells and MHC class II-positive macrophages, but not CD8(+) T cells, had infiltrated tumour tissue in mice treated with DC/BNL + IL-12. Flow cytometric analysis of tumour-infiltrating cells in mice treated with DC/BNL + IL-12 showed increases in CD4+ T cells and MHC class II+ CD11b+ cells but not in CD8+ T cells or MHC class I+ CD11b+ cells. Our results suggest that, in BNL-bearing mice treated with DC/BNL + IL-12, tumour macrophages activated by INF-gamma produced by IL-12-stimulated T cells might present BNL tumour antigens and activate DC/BNL-primed CD4+ cytotoxic T lymphocytes (CTLs) in a MHC class II-dependent manner, leading to perforin-mediated bystander killing of neighbouring MHC class II-negative tumour cells.