Triple expression of B7-1, B7-2 and 4-1BBL enhanced antitumor immune response against mouse H22 hepatocellular carcinoma

Development and Verification of an Immune-Related Gene Pairs Prognostic Signature in Hepatocellular Carcinoma

With the increasing prevalence of Hepatocellular carcinoma (HCC) and the poor prognosis of immunotherapy, reliable immune-related gene pairs (IRGPs) prognostic signature is required for personalized management and treatment of patients. Gene expression profiles and clinical information of HCC patients were obtained from the TCGA and ICGC databases. The IRGPs are constructed using immune-related genes (IRGs) with large variations. The least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct IRGPs signature. The IRGPs signature was verified through the ICGC cohort. 1,309 IRGPs were constructed from 90 IRGs with high variability. We obtained 50 IRGPs that were significantly connected to the prognosis and constructed a signature that included 17 IRGPs. In the TCGA and ICGC cohorts, patients were divided into high and low-risk patients by the IRGPs signature. The overall survival time of low-risk patients is longer than that of high-risk patients. After adjustment for clinical and pathological factors, multivariate analysis showed that the IRGPs signature is an independent prognostic factor. The Receiver operating characteristic (ROC) curve confirmed the accuracy of the signature. Besides, gene set enrichment analysis (GSEA) revealed that the signature is related to immune biological processes, and the immune microenvironment status is distinct in different risk patients. The proposed IRGPs signature can effectively assess the overall survival of HCC, and provide the relationship between the signature and the reactivity of immune checkpoint therapy and the sensitivity of targeted drugs, thereby providing new ideas for the diagnosis and treatment of the disease.

CD137 agonist induces gastric cancer cell apoptosis by enhancing the functions of CD8+ T cells via NF-κB signaling

Background

CD137 is a target for tumor immunotherapy. However, the role of CD137 in gastric cancer (GC), especially in inducing GC cell apoptosis, has not been studied.

Methods

Foxp3⁺ and CD8⁺ T cells in GCs were investigated using immunohistochemistry (IHC). CD137 expression in GCs was detected using flow cytometry, IHC and immunofluorescence (IF). Peripheral blood mononuclear cells (PBMCs) and CD8⁺ T cells isolated from peripheral blood were stimulated with a CD137 agonist in vitro. CD8⁺ T cell proliferation and p65 expression was examined using flow cytometry. P65 nuclear translocation was analyzed using IF. IL-10, TGF-β, IFN-γ, perforin and granzyme B were detected using real-time quantitative PCR (real-time PCR). PBMCs and primary GC cells were cocultured and stimulated with a CD137 agonist in vitro. Apoptosis of primary GC cells was detected using flow cytometry.

Results

Our data demonstrated that GC tumors showed characteristics of an immunosuppressive microenvironment. CD137 was predominantly expressed in CD8⁺ T cells in GCs and had a positive correlation with tumor cell differentiation. The CD137 agonist promoted CD8⁺ T cell proliferation and increased the secretion of IFN-γ, perforin and granzyme B, which induced primary GC cell apoptosis. Mechanistically, this study found that the CD137 agonist induced NF-κB nuclear translocation in CD8⁺ T cells.

Conclusion

Our results demonstrated that a CD137 agonist induced primary GC cell apoptosis by enhancing CD8⁺ T cells via activation of NF-κB signaling.

Comprehensive molecular profiling of the B7 family in gastrointestinal cancer

OBJECTIVES

B7 family has been identified as co-stimulatory or co-inhibitory molecules on T-cell response and plays an important role in tumour mortality and malignancy. In this study, the expression pattern of B7 family in gastrointestinal (GI) cancer was examined. Its upstream regulating mechanism, downstream targets and association with clinical parameters were also studied.

MATERIALS AND METHODS

The expression level of B7 members was analysed by FIREHOUSE. The gene mutation, DNA methylation, association with clinical parameters and downstream network of B7 members were analysed in cBioportal. The mutation frequency was analysed by Catalogue of Somatic Mutations in Cancer (COSMIC) analysis. The phylogenetic tree was constructed in MEGA7. The interaction protein domain analysis was performed by Pfam 31.0.

RESULTS

Differential expression of B7 family molecules was detected in different kinds of GI cancer. High-frequency gene alteration was found in tumour samples. There was negative correlation of promoter methylation and mRNA expression of B7 family members in tumour samples, suggesting the epigenetic basis of B7 family gene deregulation in GI cancer. The overexpression of B7-H1 in pancreatic cancer, B7-H5 in oesophageal cancer and B7-H6 in liver cancer were significantly associated with worse overall survival. Finally, by network analysis, we identified some potential interacting proteins for B7-1/2 and B7-H1/DC.

CONCLUSIONS

Overall, our study suggested that B7 member deregulation was strongly involved in GI cancer tumorigenesis.

Identification of a p53 target, CD137L, that mediates growth suppression and immune response of osteosarcoma cells

p53 encodes a transcription factor that transactivates downstream target genes involved in tumour suppression. Although osteosarcoma frequently has p53 mutations, the role of p53 in osteosarcomagenesis is not fully understood. To explore p53-target genes comprehensively in calvarial bone and find out novel druggable p53 target genes for osteosarcoma, we performed RNA sequencing using the calvarial bone and 23 other tissues from p53^+/+ and p53^−/− mice after radiation exposure. Of 23,813 genes, 69 genes were induced more than two-fold in irradiated p53^+/+ calvarial bone, and 127 genes were repressed. Pathway analysis of the p53-induced genes showed that genes associated with cytokine-cytokine receptor interactions were enriched. Three genes, CD137L, CDC42 binding protein kinase gamma and Follistatin, were identified as novel direct p53 target genes that exhibited growth-suppressive effects on osteosarcoma cell lines. Of the three genes, costimulatory molecule Cd137l was induced only in calvarial bone among the 24 tissues tested. CD137L-expressing cells exhibited growth-suppressive effects in vivo. In addition, recombinant Fc-fusion Cd137l protein activated the immune response in vitro and suppressed osteosarcoma cell growth in vivo. We clarified the role of CD137L in osteosarcomagenesis and its potential therapeutic application. Our transcriptome analysis also indicated the regulation of the immune response through p53.

Tumor-targeted costimulation with antibody-fusion proteins improves bispecific antibody-mediated immune response in presence of immunosuppressive factors

Therapeutic strategies aiming for the induction of an effective immune response at the tumor site can be severely hampered by the encounter of an immunosuppressive microenvironment. We investigated here the potential of concerted costimulation by tumor-directed antibody-fusion proteins with B7.1, 4-1BBL and OX40L to enforce bispecific antibody-induced T cell stimulation in presence of recognized immunosuppressive factors including IL-10, TGF-β, indoleamine 2,3-dioxygenase (IDO), PD-L1 and regulatory T cells. The expression and activity of these factors was demonstrated in the HT1080-FAP/PBMC co-culture setting, where individual and combined costimulation were still capable to enhance T cell stimulation, even though the general activation level was reduced. Additional blockade of TGF-ß or PD-1 resulted especially effective in further enhancing the degree of T cell activation. Here, best outcome was achieved by combined costimulation of targeted 4-1BBL and B7.1. Furthermore, their individual impact on the proliferation of naïve, memory and effector CD8⁺ and CD4⁺ T cell subsets, suggest the coverage of a comprehensive T cell response. Thus, our costimulatory antibody-fusion proteins show great potential to support T cell activation in adverse conditions dictated by the tumor microenvironment.

4-1BB Agonists: Multi-Potent Potentiators of Tumor Immunity

Immunotherapy is a rapidly expanding field of oncology aimed at targeting, not the tumor itself, but the immune system combating the cancerous lesion. Of the many approaches currently under study to boost anti-tumor immune responses; modulation of immune co-receptors on lymphocytes in the tumor microenvironment has thus far proven to be the most effective. Antibody blockade of the T cell co-inhibitory receptor cytotoxic T lymphocyte antigen-4 (CTLA-4) has become the first FDA approved immune checkpoint blockade; however, tumor infiltrating lymphocytes express a diverse array of additional stimulatory and inhibitory co-receptors, which can be targeted to boost tumor immunity. Among these, the co-stimulatory receptor 4-1BB (CD137/TNFSF9) possesses an unequaled capacity for both activation and pro-inflammatory polarization of anti-tumor lymphocytes. While functional studies of 4-1BB have focused on its prominent role in augmenting cytotoxic CD8 T cells, 4-1BB can also modulate the activity of CD4 T cells, B cells, natural killer cells, monocytes, macrophages, and dendritic cells. 4-1BB’s expression on both T cells and antigen presenting cells, coupled with its capacity to promote survival, expansion, and enhanced effector function of activated T cells, has made it an alluring target for tumor immunotherapy. In contrast to immune checkpoint blocking antibodies, 4-1BB agonists can both potentiate anti-tumor and anti-viral immunity, while at the same time ameliorating autoimmune disease. Despite this, 4-1BB agonists can trigger high grade liver inflammation which has slowed their clinical development. In this review, we discuss how the underlying immunobiology of 4-1BB activation suggests the potential for therapeutically synergistic combination strategies in which immune adverse events can be minimized.

CD4 T-cells transduced with CD80 and 4-1BBL mRNA induce long-term CD8 T-cell responses resulting in potent antitumor effects

Therapeutic cancer vaccines are an attractive alternative to conventional therapies to treat malignant tumors, and more importantly, to prevent recurrence after primary therapy. However, the availability of professional antigen-presenting cells (APCs) has been restricted by difficulties encountered in obtaining sufficient professional APCs for clinical use. We have prepared an alternative cellular vaccine with CD4 T-cells that can be expanded easily to yield a pure and homogeneous population in vitro. To enhance their potency as a therapeutic vaccine, in vitro expanded CD4 T-cells were transfected with RNAs encoding the costimulatory ligands CD80, 4-1BBL, or both (CD80-T, 4-1BBL-T, and CD80/4-1BBL-T-cells, respectively). We observed augmented cell vitality in CD80/4-1BBL-T-cells in vitro and in vivo. Significant CD8 T-cell responses eliciting in vivo proliferation and cytotoxicity were obtained with CD80/4-1BBL-T-cell vaccination compared to CD80-T and 4-1BBL-T-cell vaccinations. In contrast, β2m-deficient CD80/4-1BBL-T-cells were not as effective as wile-type CD80/4-1BBL-T-cells in priming CD8 T-cells. Furthermore, CD80/4-1BBL-T-cell immunization resulted in curing established EG7 tumors, resulting in the generation of memory CD8 T-cell responses, and elicited therapeutic antitumor responses against B16 melanoma. These results suggest that CD4 T-cells endowed with costimulatory ligands allow the design of effective vaccination strategies against cancer.

T-cell engager-armed oncolytic vaccinia virus significantly enhances antitumor therapy

Oncolytic vaccinia virus (VV) therapy has shown promise in preclinical models and in clinical studies. However, complete responses have rarely been observed. This lack of efficacy is most likely due to suboptimal virus spread through the tumor resulting in limited tumor cell destruction. We reasoned that redirecting T cells to the tumor has the potential to improve the antitumor activity of oncolytic VVs. We, therefore, constructed a VV encoding a secretory bispecific T-cell engager consisting of two single- chain variable fragments specific for CD3 and the tumor cell surface antigen EphA2 (EphA2-T-cell engager-armed VV (EphA2-TEA-VV)). In vitro, EphA2-TEA-VV's ability to replicate and induce oncolysis was similar to that of unmodified virus. However, only tumor cells infected with EphA2-TEA-VV induced T-cell activation as judged by the secretion of interferon-γ and interleukin-2. In coculture assays, EphA2-TEA-VV not only killed infected tumor cells, but in the presence of T cells, it also induced bystander killing of noninfected tumor cells. In vivo, EphA2-TEA-VV plus T cells had potent antitumor activity in comparison with control VV plus T cells in a lung cancer xenograft model. Thus, arming oncolytic VVs with T-cell engagers may represent a promising approach to improve oncolytic virus therapy.

Combining antibody-directed presentation of IL-15 and 4-1BBL in a trifunctional fusion protein for cancer immunotherapy

Influencing the cytokine receptor network that modulates the immune response holds great potential for cancer immunotherapy. Although encouraging results have been obtained by focusing on individual members of the common γ-chain (γc) receptor family and TNF receptor superfamily so far, combination strategies might be required to further improve the effectiveness of the antitumor response. Here, we propose the combination of interleukin (IL)-15 and 4-1BBL in a single, tumor-directed molecule. Therefore, a trifunctional antibody fusion protein was generated, composed of a tumor-specific recombinant antibody, IL-15 linked to a fragment of the IL-15Rα chain (RD) and the extracellular domain of 4-1BBL. In soluble and targeted forms, the trifunctional antibody fusion protein RD_IL-15_scFv_4-1BBL was shown to stimulate activated T-cell proliferation and induce T-cell cytotoxicity to a similar degree as the bifunctional scFv_RD_IL-15 fusion protein. On the other hand, in targeted form, the trifunctional fusion protein was much more effective in inducing T-cell proliferation and IFN-γ release of unstimulated peripheral blood mononuclear cells (PBMC). Here, the additional signal enhancement could be attributed to the costimulatory activity of 4-1BBL, indicating a clear benefit for the simultaneous presentation of IL-15 and 4-1BBL in one molecule. Furthermore, the trifunctional antibody fusion protein was more effective than the corresponding bifunctional fusion proteins in reducing metastases in a tumor mouse model in vivo. Hence, the targeted combination of IL-15 and 4-BBL in the form of a trifunctional antibody-fusion protein is a promising new approach for cancer immunotherapy.

Evaluating combinations of costimulatory antibody-ligand fusion proteins for targeted cancer immunotherapy

Combinatory strategies are becoming of increasing interest in cancer immunotherapy. Costimulation by individual members of the immunoglobulin-like (Ig)- and TNF superfamily have already shown promising antitumor potential, thus prompting the exploration of their synergistic abilities in combinatorial approaches. Here, we pursued a targeted strategy with antibody-fusion proteins composed of a tumor-directed antibody and the extracellular domain of the costimulatory ligand B7.1, 4-1BBL, OX40L, GITRL or LIGHT, respectively. Costimulatory activity was assessed in an experimental setting where initial T cell activation was induced by a bispecific antibody (tumor-related antigen × CD3). Advantage of combined targeted costimulation was shown for either B7.1 or 4-1BBL with OX40L, GITRL, LIGHT and 4-1BBL in terms of T cell proliferation and IFN-γ release. Since encouraging results were obtained by the combination of B7.1 and 4-1BBL, we adapted the model system for a time-shift setting. Here, enhanced proliferation and granzyme B expression as well as reduced PD-1 expression on the T cell population demonstrated the benefit of costimulation-assisted restimulation. Finally, the antitumor potential of this combinatorial setting was confirmed in vivo in a lung metastasis mouse model. Thus, combinatorial approaches with costimulatory antibody-ligand fusion proteins seem a promising strategy to be further investigated for cancer immunotherapy.

Identification and quantification of total coumarins from Urtica dentata Hand and its roles in promoting immune tolerance via TLR4-mediated dendritic cell immaturation

Urtica dentata Hand (UDH) is traditionally used in the Alpine region as a herbal medicine. Immunotherapy using total coumarins (TC) of UDH has been proposed, yet the cellular and molecular mechanisms remain incompletely characterized. Additionally, there is no method available for the quantification of the main coumarins in UDH. We describe maturation-resistant, TC-conditioned dendritic cell (DC), which expressed much lower MHC class II (I-Ak) and CD86, showed reduced capacity to stimulate effector T cell responses and upregulated PD-Ll (programmed death ligand-1). TC-DC-stimulated regulatory cells (Treg) were superior alloantigen-specific suppressor of the T effector response as compared to those stimulated by control (CTR)-DC. Furthermore, TC-conditioned DC increased the levels of Foxp3 and CTLA-4 in the CD25 T cell population. TC-DC downregulated toll like receptor 4 (TLR4) protein expression in response to LPS. This indicates that down-regulation of TLR4 in response to TC on DC is a critical signaling pathway that regulates the phenotype and function of DC. We also established a sensitive and specific high-performance liquid chromatography-diodearray detection-mass spectrometry (HPLC-DAD-MS) method for simultaneous identification of its main coumarins, 6,6',7,7'-tetramethoxyl-8,8'-biscoumarin (1), 7,7'-dihydroxy-6,6'-dimethoxy-8,8'-biscoumarin (2), 7,7'-dimethoxy-6,6'-biscoumarin (3), and scoparone (4). A demonstration of this mechanism and the method for identification and quantification of TC in UDH endorsed their potential as a tolerance-promoting herbal medicine to prevent or treat transplantation rejection and autoimmune diseases.

Targeting costimulatory molecules to improve antitumor immunity

The full activation of T cells necessitates the concomitant activation of two signals, the engagement of T-cell receptor by peptide/major histocompatibility complex II and an additional signal delivered by costimulatory molecules. The best characterized costimulatory molecules belong to B7/CD28 and TNF/TNFR families and play crucial roles in the modulation of immune response and improvement of antitumor immunity. Unfortunately, tumors often generate an immunosuppressive microenvironment, where T-cell response is attenuated by the lack of costimulatory molecules on the surface of cancer cells. Thus, targeting costimulatory pathways represent an attractive therapeutic strategy to enhance the antitumor immunity in several human cancers. Here, latest therapeutic approaches targeting costimulatory molecules will be described.