Alpha-Type 1 Polarized Dendritic Cells Loaded with Apoptotic Allogeneic Breast Cancer Cells Can Induce Potent Cytotoxic T Lymphocytes against Breast Cancer

Extending traditional antibody therapies: Novel discoveries in immunotherapy and clinical applications

Immunotherapy has been well regarded as one of the safer and antigen-specific anti-cancer treatments compared to first-generation chemotherapy. Since Coley's discovery, researchers focused on engineering novel antibody-based therapies. Including artificial and modified antibodies, such as antibody fragments, antibody-drug conjugates, and synthetic mimetics, the variety of immunotherapy has been rapidly expanding in the last few decades. Genetic and chemical modifications to monoclonal antibody have been brought into academia, in vivo trials, and clinical applications. Here, we have looked around antibodies overall. First, we elucidate the antibody structure and its cytotoxicity mechanisms. Second, types of therapeutic antibodies are presented. Additionally, there is a summarized list of US Food and Drug Administration (FDA)-approved therapeutic antibodies and recent clinical trials. This review provides a comprehensive overview of both the general function of therapeutic antibodies and a few main variations in development, including recent advent with the proposed mechanism of actions, and we introduce types of therapeutic antibodies, clinical trials, and approved commercial immunotherapeutic drugs.

Usefulness of IL-21, IL-7, and IL-15 conditioned media for expansion of antigen-specific CD8+ T cells from healthy donor-PBMCs suitable for immunotherapy

Clonal anergy and depletion of antigen-specific CD8+ T cells are characteristics of immunosuppressed patients such as cancer and post-transplant patients. This has promoted translational research on the adoptive transfer of T cells to restore the antigen-specific cellular immunity in these patients. In the present work, we compared the capability of PBMCs and two types of mature monocyte-derived DCs (moDCs) to prime and to expand ex-vivo antigen-specific CD8+ T cells using culture conditioned media supplemented with IL-7, IL-15, and IL-21. The data obtained suggest that protocols involving moDCs are as efficient as PBMCs-based cultures in expanding antigen-specific CD8+ T cell to ELA and CMV model epitopes. These three gamma common chain cytokines promote the expansion of naïve-like and central memory CD8+ T cells in PBMCs-based cultures and the expansion of effector memory T cells when moDCs were used. Our results provide new insights into the use of media supplemented with IL-7, IL-15, and IL-21 for the in-vitro expansion of early-differentiated antigen-specific CD8+ T cells for immunotherapy purposes.

Enhanced Human T Lymphocyte Antigen Priming by Cytokine-Matured Dendritic Cells Overexpressing Bcl-2 and IL-12

Dendritic cell (DC)-based vaccination is a promising immunotherapeutic strategy for cancer. However, clinical trials have shown only limited efficacy, suggesting the need to optimize protocols for human DC vaccine preparation. In this study, we systemically compared five different human DC vaccine maturation protocols used in clinical trials: (1) a four-cytokine cocktail (TNF-α, IL-6, IL-1β, and PGE2); (2) an α-DC-cytokine cocktail (TNF-α, IL-1β, IFN-α, IFN-γ, and poly I:C); (3) lipopolysaccharide (LPS)/IFN-γ; (4) TNF-α and PGE2; and (5) TriMix (mRNAs encoding CD40L, CD70, and constitutively active Toll-like receptor 4 electroporated into immature DCs). We found that the four-cytokine cocktail induced high levels of costimulatory and HLA molecules, as well as CCR7, in DCs. Mature DCs (mDCs) matured with the four-cytokine cocktail had higher viability than those obtained with the other protocols. Based on these features, we chose the four-cytokine cocktail protocol to further improve the immunizing capability of DCs by introducing exogenous genes. We showed that introducing exogenous Bcl-2 increased DC survival. Furthermore, introducing IL-12p70 rescued the inhibition of IL-12 secretion by PGE2 without impairing the DC phenotype. Introducing both Bcl-2 and IL-12p70 mRNAs into DCs induced enhanced cytomegalovirus pp65-specific CD8⁺ T cells secreting IFN-γ and TNF-α. Taken together, our data suggest that DC matured by the four-cytokine cocktail combined with exogenous Bcl-2 and IL-12p70 gene expression represents a promising approach for clinical applications in cancer immunotherapy.

Tumor lysate-loaded Bacterial Ghosts as a tool for optimized production of therapeutic dendritic cell-based cancer vaccines

Cancer immunotherapy with dendritic cell (DC)-based vaccines has been used to treat various malignancies for more than two decades, however generally showed a limited clinical success. Among various factors responsible for their modest clinical activity is the lack of universally applied, standardized protocols for the generation of clinical-grade DC vaccines, capable of inducing effective anti-tumor immune responses. We investigated Bacterial Ghosts (BGs) - empty envelopes of Gram-negative bacteria - as a tool for optimized production of DC vaccines. BGs possess various intact cell surface structures, exhibiting strong adjuvant properties required for the induction of DC maturation, whereas their empty internal space can be easily filled with a source tumor antigens, e.g. tumor lysate. Hence BGs emerge as an excellent platform for both the induction of immunogenic DC maturation and loading with tumor antigens in a single-step procedure. We compared the phenotype, cytokine secretion profile, functional activity and ability to induce immunogenic T-cell responses in vitro of human monocyte-derived DCs generated using BG platform and DCs matured with widely used lipopolysaccharide (LPS) plus interferon-γ cocktail and loaded with tumor lysate. Both approaches induced DC maturation, however BG-based protocol was superior to LPS-based protocol in terms of the ability to induce DCs with a lower tolerogenic potential, resulting in a more robust CD8⁺ T cell activation and their functional activity as well as significantly lower induction of regulatory T cells. These superior parameters are attributed, at least in part, to the ability of BG-matured DCs to resist potential immunosuppressive and pro-tolerogenic activity of various tumor cell lysates, including melanoma, renal carcinoma and glioblastoma.

Identification of proteins derived from Listeria monocytogenes inducing human dendritic cell maturation

Dendritic cells (DCs) are potent antigen-presenting cells (APCs) that can promote antitumor immunity when pulsed with tumor antigens and then matured by stimulatory agents. Despite apparent progress in DC-based cancer immunotherapy, some discrepancies were reported in generating potent DCs. Listeria monocytogenes as an intracellular microorganism is able to effectively activate DCs through engaging pattern-recognition receptors (PRRs). This study aimed to find the most potent components derived from L. monocytogenes inducing DC maturation. The preliminary results demonstrated that the ability of protein components is higher than DNA components to promote DC maturation and activation. Protein lysate fractionation demonstrated that fraction 2 HIC (obtained by hydrophobic interaction chromatography) was able to efficiently mature DCs. F2HIC-matured DCs are able to induce allogeneic CD8(+) T cells proliferation better than LPS-matured DCs and induce IFN-γ producing CD8(+) T cells. Mass spectrometry results showed that F2HIC contains 109 proteins. Based on the bioinformatics analysis for these 109 proteins, elongation factor Tu (EF-Tu) could be considered as a PRR ligand for stimulating DC maturation.

Antitumor dendritic cell-based vaccines: lessons from 20 years of clinical trials and future perspectives

Dendritic cells (DCs) are versatile elements of the immune system and are best known for their unparalleled ability to initiate and modulate adaptive immune responses. During the past few decades, DCs have been the subject of numerous studies seeking new immunotherapeutic strategies against cancer. Despite the initial enthusiasm, disappointing results from early studies raised some doubts regarding the true clinical value of these approaches. However, our expanding knowledge of DC immunobiology and the definition of the optimal characteristics for antitumor immune responses have allowed a more rational development of DC-based immunotherapies in recent years. Here, after a brief overview of DC immunobiology, we sought to systematize the knowledge provided by 20 years of clinical trials, with a special emphasis on the diversity of approaches used to manipulate DCs and their consequent impact on vaccine effectiveness. We also address how new therapeutic concepts, namely the combination of DC vaccines with other anticancer therapies, are being implemented and are leveraging clinical outcomes. Finally, optimization strategies, new insights, and future perspectives on the field are also highlighted.

Branched Polyethylenimine-Superparamagnetic Iron Oxide Nanoparticles (bPEI-SPIONs) Improve the Immunogenicity of Tumor Antigens and Enhance Th1 Polarization of Dendritic Cells

Nanoparticles in the field of dendritic cell (DC) research are emerging as a promising method of enhancing the efficacy of cancer immunotherapy. We investigated the effect of branched polyethylenimine-superparamagnetic iron oxide nanoparticles (bPEI-SPIONs) on tumor cells loaded onto DCs. The tumor antigens were prepared as follows: (1) apoptotic U266 cells with ultraviolet B (UVB) irradiation followed by a 2 h incubation in the absence (2 h postirradiated cells) or (2) presence of bPEI-SPIONs (bPEI-SPION 2 h postirradiated cells) and (3) apoptotic U266 cells with UVB irradiation followed by an overnight 16 h incubation (16 h postirradiated cells). bPEI-SPIONs render U266 cells sensitive to UVB irradiation through reactive oxygen species production to accelerate apoptotic death. The 2 h postirradiated cells and bPEI-SPION 2 h postirradiated cells released immunogenic proteins, including Hsp70, Hsp90, and HMGB1. The DCs loaded with bPEI-SPION 2 h postirradiated cells showed the highest IL-12p70 production and Th1 polarization compared with other DCs. These results suggest that bPEI-SPIONs are a promising method of enhancing the immunogenicity of tumor cells and promoting Th1 polarization of DCs loaded with these tumor cells.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

Generation of potent cytotoxic T lymphocytes against castration-resistant prostate cancer cells by dendritic cells loaded with dying allogeneic prostate cancer cells

To induce a potent cytotoxic T lymphocyte (CTL) response in dendritic cell (DC)-based immunotherapy against prostate cancer, various tumour antigens should be loaded onto DCs. The aim of this study was to establish a method of immunotherapy for castration-resistant prostate cancer (CRPC) using prostate cancer-specific CTLs generated in vitro by DCs. Monocyte-derived DCs from patients with CRPC were induced to mature using a standard cytokine cocktail (in IL-1β, TNF-α, IL-6 and PGE(2) : standard DCs, sDCs) or using an α-type 1-polarized DC (αDC1) cocktail (in IL-1β, TNF-α, IFN-α, IFN-γ and polyinosinic:polycytidylic acid) and loaded with the UVB-irradiated CRPC cell line PC-3. Antigen-loaded DCs were evaluated by morphological and functional assays. The αDC1s significantly increased the expression of several molecules related to DC maturation, regardless of whether the αDC1s were loaded with tumour antigens or not, compared to sDCs. The αDC1s showed a higher production of interleukin-12 both during maturation and after subsequent stimulation with CD40L, which was not significantly affected by loading with tumour antigens, as compared to standard DCs (sDCs). Prostate cancer-specific CTLs against autologous CRPC cells were successfully induced by αDC1s loaded with dying PC-3 cells. Autologous αDC1s loaded with an allogeneic CRPC cell line can generate greater CRPC-specific CTL responses as compared to sDCs and may provide a novel source of DC-based vaccines that can be used for the development of immunotherapy in patients with CRPC.

Dendritic cell engineering for tumor immunotherapy: from biology to clinical translation

Dendritic cells (DCs) are the most potent APCs, with the ability to orchestrate a repertoire of immune responses. DCs play a pivotal role in the initiation, programming and regulation of tumor-specific immune responses, as they are poised to take up, process and present tumor antigens to naive or effector T lymphocytes. Although, to an extent, DC-based immunotherapeutic strategies have successfully induced specific anti-tumor responses in animal models, their clinical efficacy has rarely been translated into the clinic. This article attempts to present a complete picture of recent developments of DC-based therapeutic strategies addressing multiple components of tumor immunoenvironment. It also showcases certain practical intricacies in order to explore novel strategies for providing new impetus to DC-based cancer vaccination.