Dendritic cells as therapeutic vaccines against cancer

Protein-Based Artificial Nanosystems in Cancer Therapy

Proteins, like actors, play different roles in specific applications. In the past decade, significant achievements have been made in protein-engineered biomedicine for cancer therapy. Certain proteins such as human serum albumin, working as carriers for drug/photosensitizer delivery, have entered clinical use due to their long half-life, biocompatibility, biodegradability, and inherent nonimmunogenicity. Proteins with catalytic abilities are promising as adjuvant agents for other therapeutic modalities or as anticancer drugs themselves. These catalytic proteins are usually defined as enzymes with high biological activity and substrate specificity. However, clinical applications of these kinds of proteins remain rare due to protease-induced denaturation and weak cellular permeability. Based on the characteristics of different proteins, tailor-made protein-based nanosystems could make up for their individual deficiencies. Therefore, elaborately designed protein-based nanosystems, where proteins serve as drug carriers, adjuvant agents, or therapeutic drugs to make full use of their intrinsic advantages in cancer therapy, are reviewed. Up-to-date progress on research in the field of protein-based nanomedicine is provided.

Annona muricata L.-Derived Polysaccharides as a Potential Adjuvant to a Dendritic Cell-Based Vaccine in a Thymoma-Bearing Model

Dendritic cells (DCs) are powerful antigen-presenting cells that are often used to evaluate adjuvants, particularly for adjuvant selection for various vaccines. Here, polysaccharides (named ALP) isolated from leaves of Annona muricata L., which are used in traditional medicine such as for bacterial infections and inflammatory diseases, were evaluated as an adjuvant candidate that can induce anti-tumor activity. We first confirmed the phenotypic (surface molecules, cytokines, antigen uptake, and antigen-presenting ability) and functional alterations (T cell proliferation/activation) of DCs in vitro. We also confirmed the adjuvant effect by evaluating anti-tumor activity and immunity using an ALP-treated DC-immunized mouse model. ALP functionally induced DC maturation by up-regulating the secretion of Th1-polarizing pro-inflammatory cytokines, the expression of surface molecules, and antigen-presenting ability. ALP triggered DC maturation, which is dependent on the activation of the MAPK and NF-κB signaling pathways. ALP-activated DCs showed an ample capacity to differentiate naive T cells to Th1 and activated CD8⁺ T cells effectively. The systemic administration of DCs that pulse ALP and ovalbumin peptides strongly increased cytotoxic T lymphocyte (CTL) activity (by 9.5% compared to that in the control vaccine groups), the generation of CD107a-producing multifunctional T cells, and Th1-mediated humoral immunity, and caused a significant reduction (increased protection by 29% over that in control vaccine groups) in tumor growth. ALP, which triggers the Th1 and CTL response, provides a basis for a new adjuvant for various vaccines.

An integrative histopathologic clustering model based on immuno-matrix elements to predict the risk of death in malignant mesothelioma

Objective

Previous studies have reported a close relationship between malignant mesothelioma (MM) and the immune matricial microenvironment (IMM). One of the major problems in these studies is the lack of adequate adjustment for potential confounders. Therefore, the aim of this study was to identify and quantify risk factors such as IMM and various tumor characteristics and their association with the subtype of MM and survival.

Methods

We examined IMM and other tumor markers in tumor tissues from 82 patients with MM. These markers were evaluated by histochemistry, immunohistochemistry, immunofluorescence, and morphometry. Logistic regression analysis, cluster analysis, and Cox regression analysis were performed.

Results

Hierarchical cluster analysis revealed two clusters of MM that were independent of clinicopathologic features. The high‐risk cluster included MM with high tumor cellularity, high type V collagen (Col V) fiber density, and low CD8⁺ T lymphocyte density in the IMM. Our results showed that the risk of death was increased for patients with MM with high tumor cellularity (OR = 1.63, 95% CI = 1.29‐2.89, P = .02), overexpression of Col V (OR = 2.60, 95% CI = 0.98‐6.84, P = .04), and decreased CD8 T lymphocytes (OR = 1.001, 95% CI = 0.995‐1.007, P = .008). The hazard ratio for the high‐risk cluster was 2.19 (95% CI = 0.54‐3.03, P < .01) for mortality from MM at 40 months.

Conclusion

Morphometric analysis of Col V, CD8⁺ T lymphocytes, and tumor cellularity can be used to identify patients with high risk of death from MM.

Biomimetic Nanotechnology toward Personalized Vaccines

While traditional approaches for disease management in the era of modern medicine have saved countless lives and enhanced patient well-being, it is clear that there is significant room to improve upon the current status quo. For infectious diseases, the steady rise of antibiotic resistance has resulted in super pathogens that do not respond to most approved drugs. In the field of cancer treatment, the idea of a cure-all silver bullet has long been abandoned. As a result of the challenges facing current treatment and prevention paradigms in the clinic, there is an increasing push for personalized therapeutics, where plans for medical care are established on a patient-by-patient basis. Along these lines, vaccines, both against bacteria and tumors, are a clinical modality that could benefit significantly from personalization. Effective vaccination strategies could help to address many challenging disease conditions, but current vaccines are limited by factors such as a lack of potency and antigenic breadth. Recently, researchers have turned toward the use of biomimetic nanotechnology as a means of addressing these hurdles. Recent progress in the development of biomimetic nanovaccines for antibacterial and anticancer applications is discussed, with an emphasis on their potential for personalized medicine.

Design strategy of optical probes for tumor hypoxia imaging

Clinical manifestations of tumors indicate that malignant phenotypes developing in the hypoxic microenvironment lead to resistance to cancer treatment, rendering chemotherapy, radiotherapy, and photodynamic therapy less sensitive and effective in patients with tumor. Visualizing the oxygen level in the tumor environment has garnered much attention due to its implications in precision tumor therapy. Following the rapid development of biomaterials in nanotechnology, various nanomaterials have been designed to visualize the oxygen levels in tumors. Here, we review recent research on detecting oxygen levels in solid tumors for tumor hypoxia imaging. To monitor the hypoxic level of tumors, two main strategies were investigated: directly detecting oxygen levels in tumors and monitoring the hypoxia-assisted reduced microenvironment. We believe that hypoxia as a tumor-specific microenvironment can be a breakthrough in the clinical treatment of tumors.

Escherichia coli adhesion portion FimH functions as an adjuvant for cancer immunotherapy

Induction of antigen-specific immune activation by the maturation of dendritic cells (DCs) is a strategy used for cancer immunotherapy. In this study, we find that FimH, which is an Escherichia coli adhesion portion, induces toll-like receptor 4-dependent and myeloid differentiation protein 2-independent DC maturation in mice in vivo. A combined treatment regimen with FimH and antigen promotes antigen-specific immune activation, including proliferation of T cells, production of IFN-γ and TNF-α, and infiltration of effector T cells into tumors, which consequently inhibits tumor growth in mice in vivo against melanoma and carcinoma. In addition, combined therapeutic treatment of anti-PD-L1 antibodies and FimH treatment efficiently inhibits CT26 tumor growth in BALB/c mice. Finally, FimH promotes human peripheral blood DC activation and syngeneic T-cell proliferation and activation. Taken together, these findings demonstrate that FimH can be a useful adjuvant for cancer immunotherapy.

Rapid microsphere-assisted peptide screening (MAPS) of promiscuous MHCII-binding peptides in Zika virus envelope protein

Despite promising developments in computational tools, peptide-class II MHC (MHCII) binding predictors continue to lag behind their peptide-class I MHC counterparts. Consequently, peptide-MHCII binding is often evaluated experimentally using competitive binding assays, which tend to sacrifice throughput for quantitative binding detail. Here, we developed a high-throughput semiquantitative peptide-MHCII screening strategy termed microsphere-assisted peptide screening (MAPS) that aims to balance the accuracy of competitive binding assays with the throughput of computational tools. Using MAPS, we screened a peptide library from Zika virus envelope (E) protein for binding to four common MHCII alleles (DR1, DR4, DR7, DR15). Interestingly, MAPS revealed a significant overlap between peptides that promiscuously bind multiple MHCII alleles and antibody neutralization sites. This overlap was also observed for rotavirus outer capsid glycoprotein VP7, suggesting a deeper relationship between B cell and CD4+ T cell specificity which can facilitate the design of broadly protective vaccines to Zika and other viruses.

In situ genetic engineering of tumors for long-lasting and systemic immunotherapy

There is an urgent need for improved cancer immunotherapies. The nanoparticles described here deliver genes to stimulate the immune system to specifically kill tumor cells. This synthetic, biodegradable system avoids the use of common gene delivery materials like viruses that can have safety concerns and manufacturing limitations. Local nanoparticle delivery evades adverse side effects stemming from systemic administration of immune-activating therapeutics. Importantly, this technology causes a tumor-targeting response but does not require prior knowledge of a particular patient’s gene expression profile; thus, it can serve as a platform to combat many different solid cancers. Moreover, local nanoparticle administration causes a systemic cellular immune response, which has the potential to lead to better outcomes in the context of recurrence or metastasis.

Cancer immunotherapy has been the subject of extensive research, but highly effective and broadly applicable methods remain elusive. Moreover, a general approach to engender endogenous patient-specific cellular therapy, without the need for a priori knowledge of tumor antigen, ex vivo cellular manipulation, or cellular manufacture, could dramatically reduce costs and broaden accessibility. Here, we describe a biotechnology based on synthetic, biodegradable nanoparticles that can genetically reprogram cancer cells and their microenvironment in situ so that the cancer cells can act as tumor-associated antigen-presenting cells (tAPCs) by inducing coexpression of a costimulatory molecule (4-1BBL) and immunostimulatory cytokine (IL-12). In B16-F10 melanoma and MC38 colorectal carcinoma mouse models, reprogramming nanoparticles in combination with checkpoint blockade significantly reduced tumor growth over time and, in some cases, cleared the tumor, leading to long-term survivors that were then resistant to the formation of new tumors upon rechallenge at a distant site. In vitro and in vivo analyses confirmed that locally delivered tAPC-reprogramming nanoparticles led to a significant cell-mediated cytotoxic immune response with systemic effects. The systemic tumor-specific and cell-mediated immunotherapy response was achieved without requiring a priori knowledge of tumor-expressed antigens and reflects the translational potential of this nanomedicine.

Transdermal cold atmospheric plasma-mediated immune checkpoint blockade therapy

Despite the promise of immune checkpoint blockade (ICB) therapy against cancer, challenges associated with low objective response rates and severe systemic side effects still remain and limit its clinical applications. Here, we described a cold atmospheric plasma (CAP)-mediated ICB therapy integrated with microneedles (MN) for the transdermal delivery of ICB. We found that a hollow-structured MN (hMN) patch facilitates the transportation of CAP through the skin, causing tumor cell death. The release of tumor-associated antigens then promotes the maturation of dendritic cells in the tumor-draining lymph nodes, subsequently initiating T cell-mediated immune response. Anti-programmed death-ligand 1 antibody (aPDL1), an immune checkpoint inhibitor, released from the MN patch further augments the antitumor immunity. Our findings indicate that the proposed transdermal combined CAP and ICB therapy can inhibit the tumor growth of both primary tumors and distant tumors, prolonging the survival of tumor-bearing mice.

Chemokines and their Receptors: Multifaceted Roles in Cancer Progression and Potential Value as Cancer Prognostic Markers

Chemokines are chemotactic cytokines that mediate immune cell chemotaxis and lymphoid tissue development. Recent advances have indicated that chemokines and their cognate receptors play critical roles in cancer-related inflammation and cancer progression. On the basis of these findings, the chemokine system has become a new potential drug target for cancer immunotherapy. In this review, we summarize the essential roles of the complex network of chemokines and their receptors in cancer progression. Furthermore, we discuss the potential value of the chemokine system as a cancer prognostic marker. The chemokine system regulates the infiltration of immune cells into the tumor microenvironment, which induces both pro- and anti-immunity and promotes or suppresses tumor growth and proliferation, angiogenesis, and metastasis. Increasing evidence indicates the promising prognostic value of the chemokine system in cancer patients. While CCL2, CXCL10, and CX3CL1/CX3CR1 can serve as favorable or unfavorable prognostic factors depending on the cancer types, CCL14 and XCL1 possess good prognostic value. Other chemokines such as CXCL1, CXCL8, and CXCL12 are poor prognostic markers. Despite vast advances in our understanding of the complex nature of the chemokine system in tumor biology, knowledge about the multifaceted roles of the chemokine system in different types of cancers is still limited. Further studies are necessary to decipher distinct roles within the chemokine system in terms of cancer progression and to validate their potential value in cancer prognosis.

Cell-mediated immune resistance in cancer

The genetic and epigenetic aberrations that underlie immune resistance lead to tumors that are refractory to clinically established and experimental immunotherapies, including monoclonal antibodies and T cell-based therapies. From various forms of cytotoxic T cells to small molecule inhibitors that revamp the tumor microenvironment, these therapies have demonstrated notable responses in cancer models and a resistant subset of cancer patients, used both alone and in combination. However, even current approaches, such as those targeting checkpoint molecules, tumor ligands, and involving gene-related therapies, present a challenge in non-responding patients. In this perspective, we discuss the most common mechanisms of immune resistance, including tumor heterogeneity, tumor ligand and major histocompatibility complex modulation, anti-apoptotic pathways, checkpoint inhibitory ligands, immunosuppressive cells and factors in the tumor microenvironment, and activation-induced cell death. In addition, we discuss the strategies designed to circumvent these resistance pathways to showcase the potential of emerging technologies in battling the rise of resistance.

Involvement of Heparanase in Gastric Cancer Progression and Immunotherapy

Heparanase is upregulated in various tumors, and its expression is closely associated with tumor growth, angiogenesis and metastasis, which accomplishes this mainly through degrading heparan sulfate and releasing heparin-binding growth factors thereby influencing multiple signaling pathways. In addition to its enzymatic degrading activity, heparanase can act via its non-enzymatic mechanisms that directly regulate various signaling. This review mainly focuses on the expression levels and role of heparanase in gastric cancer, and multiple genes and mechanisms regulating heparanase expression in gastric cancer. Furthermore, the development of heparanase-targeted immunotherapy and its potential application for treating gastric cancer are discussed.

A gene expression-based study on immune cell subtypes and glioma prognosis

Object

Glioma is a common malignant tumours in the central nervous system (CNS), that exhibits high morbidity, a low cure rate, and a high recurrence rate. Currently, immune cells are increasingly known to play roles in the suppression of tumourigenesis, progression and tumour growth in many tumours. Therefore, given this increasing evidence, we explored the levels of some immune cell genes for predicting the prognosis of patients with glioma.

Methods

We extracted glioma data from The Cancer Genome Atlas (TCGA). Using the Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm, the relative proportions of 22 types of infiltrating immune cells were determined. In addition, the relationships between the scales of some immune cells and sex/age were also calculated by a series of analyses. A P-value was derived for the deconvolution of each sample, providing credibility for the data analysis (P < 0.05). All analyses were conducted using R version 3.5.2. Five-year overall survival (OS) also showed the effectiveness and prognostic value of each proportion of immune cells in glioma; a bar plot, correlation-based heatmap (corheatmap), and heatmap were used to represent the proportions of immune cells in each glioma sample.

Results

In total, 703 transcriptomes from a clinical dataset of glioma patients were drawn from the TCGA database. The relative proportions of 22 types of infiltrating immune cells are presented in a bar plot and heatmap. In addition, we identified the levels of immune cells related to prognosis in patients with glioma. Activated dendritic cells (DCs), eosinophils, activated mast cells, monocytes and activated natural killer (NK) cells were positively related to prognosis in the patients with glioma; however, resting NK cells, CD8⁺ T cells, T follicular helper cells, gamma delta T cells and M0 macrophages were negatively related to prognosis in the patients with glioma. Specifically, the proportions of several immune cells were significantly related to patient age and sex. Furthermore, the level of M0 macrophages was significant in regard to interactions with other immune cells, including monocytes and gamma delta T cells, in glioma tissues through sample data analysis.

Conclusion

We performed a novel gene expression-based study of the levels of immune cell subtypes and prognosis in glioma, which has potential clinical prognostic value for patients with glioma.

Soft matter DNA nanoparticles hybridized with CpG motifs and peptide nucleic acids enable immunological treatment of cancer

Nucleic acids have been used as building blocks to assemble nanostructures by their sequence specific self-recognition properties, and resulting DNA architectures were applied as potential multifunctional drug carriers. Here, we report an amphiphilic lipid-DNA aggregate hybridized with pharmaceutically active DNA and peptide segments for cancer immunotherapy. The facile formulation of the CpG sequence and antigen peptide-bearing peptide nucleic acid representing immune-adjuvant and antigen, respectively, enabled the highly efficacious induction of antigen-specific immune activation. This immunotherapeutic formulation was evaluated in terms of multiple types of tumor growth and metastasis in vivo.

Development of an In Situ Cancer Vaccine via Combinational Radiation and Bacterial-Membrane-Coated Nanoparticles

Neoantigens induced by random mutations and specific to an individual's cancer are the most important tumor antigens recognized by T cells. Among immunologically "cold" tumors, limited recognition of tumor neoantigens results in the absence of a de novo antitumor immune response. These "cold" tumors present a clinical challenge as they are poorly responsive to most immunotherapies, including immune checkpoint inhibitors (ICIs). Radiation therapy (RT) can enhance immune recognition of "cold" tumors, resulting in a more diversified antitumor T-cell response, yet RT alone rarely results in a systemic antitumor immune response. Therefore, a multifunctional bacterial membrane-coated nanoparticle (BNP) composed of an immune activating PC7A/CpG polyplex core coated with bacterial membrane and imide groups to enhance antigen retrieval is developed. This BNP can capture cancer neoantigens following RT, enhance their uptake in dendritic cells (DCs), and facilitate their cross presentation to stimulate an antitumor T-cell response. In mice bearing syngeneic melanoma or neuroblastoma, treatment with BNP+RT results in activation of DCs and effector T cells, marked tumor regression, and tumor-specific antitumor immune memory. This BNP facilitates in situ immune recognition of a radiated tumor, enabling a novel personalized approach to cancer immunotherapy using off-the-shelf therapeutics.

Dendritic Cells/Macrophages-Targeting Feature of Ebola Glycoprotein and its Potential as Immunological Facilitator for Antiviral Vaccine Approach

In the prevention of epidemic and pandemic viral infection, the use of the antiviral vaccine has been the most successful biotechnological and biomedical approach. In recent times, vaccine development studies have focused on recruiting and targeting immunogens to dendritic cells (DCs) and macrophages to induce innate and adaptive immune responses. Interestingly, Ebola virus (EBOV) glycoprotein (GP) has a strong binding affinity with DCs and macrophages. Shreds of evidence have also shown that the interaction between EBOV GP with DCs and macrophages leads to massive recruitment of DCs and macrophages capable of regulating innate and adaptive immune responses. Therefore, studies for the development of vaccine can utilize the affinity between EBOV GP and DCs/macrophages as a novel immunological approach to induce both innate and acquired immune responses. In this review, we will discuss the unique features of EBOV GP to target the DC, and its potential to elicit strong immune responses while targeting DCs/macrophages. This review hopes to suggest and stimulate thoughts of developing a stronger and effective DC-targeting vaccine for diverse virus infection using EBOV GP.

Intracellularly Generated Immunological Gold Nanoparticles for Combinatorial Photothermal Therapy and Immunotherapy against Tumor

Gold nanoparticle (AuNP) has been widely used in cancer photothermal therapy (PTT) for ablating accessible tumor, while it is insufficient for inhibiting tumor metastasis and relapse in current stage. Here, we first developed a novel immunological AuNP through intracellular generation and exocytosis for combinatorial PTT and immunotherapy. Melanoma B16F10 cells were employed to generate AuNPs first and then shed nanoparticle trapped vesicles to extracellular environment with retained tumor antigens (AuNP@B16F10). By further introducing the nanoparticles into dendritic cells (DCs), DC-derived AuNPs (AuNP@DC_B16F10) were generated with enhanced biosafety, which can induce hyperthermia and provoke antitumor immune responses. This immunological nanoplatform demonstrated efficient inhibition or even eradication of primary tumor, tumor metastasis, as well as tumor relapse, with significantly improved overall survival of mice. With our design, the intracellularly generated AuNPs with immunological property could act as an effective treatment modality for cancer.

Membrane-encapsulated camouflaged nanomedicines in drug delivery

Owing to the limitations of conventional therapies, there has been an increasing need for nanomedicines for real-time diagnosis and effective treatment of life-threatening diseases. Despite the conceptual and technological success achieved by researchers worldwide, the complexities of biological systems, efficient engineering and formulation of monodispersed nanomedicines, inadequate information on bio–nano interactions, issues on health hazards, clinical trials and commercialization have set new challenges in biomedical research. This review highlights how the biological membrane improves the performance of nanomedicines in drug delivery. With the list of nanomedicines getting longer gradually to overcome the drawbacks of conventional therapeutics, it is important to concentrate on the interactions between nanostructures and living systems in order to improve the biocompatibility and therapeutic efficacy of functional nanomedicines.

CD90low MSCs modulate intratumoral immunity to confer antitumor activity in a mouse model of ovarian cancer

Both anti-tumoral and pro-tumoral effects of mesenchymal stem cells (MSCs) in preclinical treatment of ovarian cancer have been controversially demonstrated. In this study, we profiled the phenotypes of mouse compact bone-derived MSCs (CB-MSCs) and bone marrow-derived MSCs (BM-MSCs) and found that CB-MSCs expressed lower CD90 compared to BM-MSCs. We examined gene expression of immune regulating cytokines of CB-MSCs in 2D and 3D culture and under stimulation with TLR4 agonist LPS or immune activator VIC-008. Our data showed that when CB-MSCs were cultured in simulated in vivo 3D condition, CD90 expression was further decreased. Moreover, gene expressions of immune activating cytokines IL-12, IL-21, IFNγ and a pro-inflammatory cytokine CXCL10 in CB-MSCs were increased in 3D culture whereas gene expression of anti-inflammatory cytokines IL-10 and CCL5 were downregulated. Stimulation of CB-MSCs by LPS or VIC-008 presented similar profile of the cytokine gene expressions to that in 3D culture which might benefit the anti-tumor efficacy of CD90low MSCs. The anti-tumor effects of CD90low CB-MSCs alone or in combination with VIC-008 were evaluated in a syngeneic orthotopic mouse model of ovarian cancer. Treatment that combines CB-MSCs and VIC-008 significantly decreased tumor growth and prolonged mouse survival. This was associated with the increase of activated anti-tumoral CD4+ and CD8+ T cells and the decrease of Treg cells in the tumor microenvironment. Taken together, our study demonstrates the synergistic anti-tumoral efficacy by application of CB-MSCs combined with immune activator VIC-008 and provides new insight into CD90low MSCs as a new anti-tumor arsenal.

Recent Advances of Small Molecular Regulators Targeting G Protein- Coupled Receptors Family for Oncology Immunotherapy

The great clinical success of chimeric antigen receptor T cell (CAR-T) and PD-1/PDL-1 inhibitor therapies suggests the drawing of a cancer immunotherapy age. However, a considerable proportion of cancer patients currently receive little benefit from these treatment modalities, indicating that multiple immunosuppressive mechanisms exist in the tumor microenvironment. In this review, we mainly discuss recent advances in small molecular regulators targeting G Protein-Coupled Receptors (GPCRs) that are associated with oncology immunomodulation, including chemokine receptors, purinergic receptors, prostaglandin E receptor EP4 and opioid receptors. Moreover, we outline how they affect tumor immunity and neoplasia by regulating immune cell recruitment and modulating tumor stromal cell biology. We also summarize the data from recent clinical advances in small molecular regulators targeting these GPCRs, in combination with immune checkpoints blockers, such as PD-1/PDL-1 and CTLA4 inhibitors, for cancer treatments.

Strategies for developing and optimizing cancer vaccines

With the spotlight on cancer immunotherapy and the expanding use of immune checkpoint inhibitors, strategies to improve the response rate and duration of current cancer immunotherapeutics are highly sought. In that sense, investigators around the globe have been putting spurs on the development of effective cancer vaccines in humans after decades of efforts that led to limited clinical success. In more than three decades of research in pursuit of targeted and personalized immunotherapy, several platforms have been incorporated into the list of cancer vaccines from live viral or bacterial agents harboring antigens to synthetic peptides with the hope of stronger and durable immune responses that will tackle cancers better. Unlike adoptive cell therapy, cancer vaccines can take advantage of using a patient's entire immune system that can include more than engineered receptors or ligands in developing antigen-specific responses. Advances in molecular technology also secured the use of genetically modified genes or proteins of interest to enhance the chance of stronger immune responses. The formulation of vaccines to increase chances of immune recognition such as nanoparticles for peptide delivery is another area of great interest. Studies indicate that cancer vaccines alone may elicit tumor-specific cellular or humoral responses in immunologic assays and even regression or shrinkage of the cancer in select trials, but novel strategies, especially in combination with other cancer therapies, are under study and are likely to be critical to achieve and optimize reliable objective responses and survival benefit. In this review, cancer vaccine platforms with different approaches to deliver tumor antigens and boost immunity are discussed with the intention of summarizing what we know and what we need to improve in the clinical trial setting.

Cytotoxic Activity and Memory T Cell Subset Distribution of in vitro-Stimulated CD8+ T Cells Specific for HER2/neu Epitopes

Minimal residual disease remaining after resection of primary tumors can lead to tumor recurrence and metastasis, increasing mortality and morbidity rates among cancer patients. Thus, there is a need for new technologies for recognition and elimination of single cancer cells remaining in a patient's body after radiation therapy, chemotherapy, or surgical resection. Effector CD8⁺ T cells, also commonly known as cytotoxic T lymphocytes (CTLs), play a key role in antitumor cellular immunity and, when properly activated, are able to effectively destroy tumor cells. The aims of this study were to obtain CD8⁺ CTLs specific for the HER2/neu epitopes E75 and E88 and to assess the cytotoxic activity and composition of these cells in terms of the distribution of memory T-cell subsets. We obtained HER2-specific CD8⁺ T cells and assessed T cell subset distribution among them including naive T cells (T_N), central memory T cells (T_CM), effector memory T cells (T_EM), stem cell-like memory T cells (T_SCM) and terminally-differentiated T cells (T_EMRA) via eight-color flow cytometry. HER2-specific CTLs were largely (~40–50%) represented by T_SCM cells, a population capable of mounting pronounced antitumor immune responses due to a combination of effector function and self-maintenance. In comparison with activated peripheral blood mononuclear cells (PBMCs) and bulk CD8⁺ T cells, HER2-specific CTLs exhibited greater cytotoxicity against the HER2-expressing human breast adenocarcinoma cell line MCF-7 and produced higher levels of IFN-γ in response to tumor cells. We also showed the presence of HER2-specific CTLs in healthy individuals and increase in them in HER2-positive breast cancer patients. Collectively, our results suggest that HER2-specific CD8⁺ T cells isolated using this approach could be used for adoptive T-cell transfer to eliminate tumor cells and prevent metastasis and relapse in patients with HER2-overexpressing cancers.

Transendothelial migration (TEM) of in vitro generated dendritic cell vaccine in cancer immunotherapy

Many efforts have been made to improve the efficacy of dendritic cell (DC) vaccines in DC-based cancer immunotherapy. One of these efforts is to deliver a DC vaccine more efficiently to the regional lymph nodes (rLNs) to induce stronger anti-tumor immunity. Together with chemotaxis, transendothelial migration (TEM) is believed to be a critical and indispensable step for DC vaccine migration to the rLNs after administration. However, the mechanism underlying the in vitro-generated DC TEM in DC-based cancer immunotherapy has been largely unknown. Currently, junctional adhesion molecules (JAMs) were found to play an important role in the TEM of in vitro generated DC vaccines. This paper reviews the TEM of DC vaccines and TEM-associated JAM molecules.

Turning "Cold" Into "Hot" Tumors-Opportunities and Challenges for Radio-Immunotherapy Against Primary and Metastatic Brain Cancers

The development of immunotherapies has revolutionized intervention strategies for a variety of primary cancers. Despite this promising progress, treatment options for primary brain cancer and brain metastasis remain limited and still largely depend on surgical resection, radio- and/or chemotherapy. The paucity in the successful development of immunotherapies for brain cancers can in part be attributed to the traditional view of the brain as an immunologically privileged site. The presence of the blood-brain barrier and the absence of lymphatic drainage were believed to restrict the entry of blood-borne immune and inflammatory cells into the central nervous system (CNS), leading to an exclusion of the brain from systemic immune surveillance. However, recent insight from pre-clinical and clinical studies on the immune landscape of brain cancers challenged this dogma. Recruitment of blood-borne immune cells into the CNS provides unprecedented opportunities for the development of tumor microenvironment (TME)-targeted or immunotherapies against primary and metastatic cancers. Moreover, it is increasingly recognized that in addition to genotoxic effects, ionizing radiation represents a critical modulator of tumor-associated inflammation and synergizes with immunotherapies in adjuvant settings. This review summarizes current knowledge on the cellular and molecular identity of tumor-associated immune cells in primary and metastatic brain cancers and discusses underlying mechanisms by which ionizing radiation modulates the immune response. Detailed mechanistic insight into the effects of radiation on the unique immune landscape of brain cancers is essential for the development of multimodality intervention strategies in which immune-modulatory effects of radiotherapy are exploited to sensitize brain cancers to immunotherapies by converting immunologically “cold” into “hot” environments.

Novel Cancer Therapeutics in Geriatrics: What is Unique to the Aging Patient?

With the worldwide trend of aging populations, the number of older adults who develop and survive cancer is likely to increase. In the last decade, oncology drug development has shifted away from conventional chemotherapeutics towards agents that can 'target' a driver mutation of a specific cancer or 'unleash' the patient's native immune system to attack the cancer-so-called molecularly targeted therapies and immunotherapeutics. The basic algorithms of cancer treatment in elderly patients are essentially the same as in younger patients; however, one needs to pay exceptional attention to the effects of co-morbidities, interaction with other drugs, and the organ function reserve of an older individual before determining his/her 'eligibility' for a specific cancer treatment modality. Despite the growing evidence of safety and effectiveness of combination chemotherapy in fit elderly patients, the data are still lacking concerning the use of currently approved targeted agents and immunotherapies. The current evidence, though limited, suggests reasonable tolerability with comparable efficacy in patients > 65 years old treated with immune-based therapies to that in younger controls; however, it is unclear if this leads to significant patient-relevant gains such as improved survival with an acceptable quality of life. Nonetheless, these newer agents remain better tolerated than cytotoxic chemotherapy in clinical practice, particularly in older patients. Alternatively, a personalized approach for elderly patients with consideration of the incidence and management of adverse effects, as well as strategies for optimizing efficacy in the context of an aging immune system, would be of utmost value in our aging cancer population. Future trials should also explore immune markers to predict response to these therapeutics in elderly patients, taking into consideration the effects of immunosenescence and immune modulation in aging hosts.

Activation of Human Dendritic Cells by Ascophyllan Purified from Ascophyllum nodosum

In our previous study, we showed that ascophyllan purified from Ascophyllum nodosum treatment promotes mouse dendritic cell (DC) activation in vivo, further induces an antigen-specific immune response and has anticancer effects in mice. However, the effect of ascophyllan has not been studied in human immune cells, specifically in terms of activation of human monocyte-derived DCs (MDDCs) and human peripheral blood DCs (PBDCs). We found that the treatment with ascophyllan induced morphological changes in MDDCs and upregulated co-stimulatory molecules and major histocompatibility complex class I (MHC I) and MHC II expression. In addition, pro-inflammatory cytokine levels in culture medium was also dramatically increased following ascophyllan treatment of MDDCs. Moreover, ascophyllan promoted phosphorylation of ERK, p38 and JNK signaling pathways, and inhibition of p38 almost completely suppressed the ascophyllan-induced activation of MDDCs. Finally, treatment with ascophyllan induced activation of BDCA1 and BDCA3 PBDCs. Thus, these data suggest that ascophyllan could be used as an immune stimulator in humans.

Induction of T cell-mediated immune response by dendritic cells pulsed with mRNA of sphere-forming cells isolated from patients with gastric cancer

Gastric cancer (GC) as the third most common cause of cancer-associated mortality worldwide is one of the cancers with very high heterogeneity. Cancer stem cells (CSCs) as a small subset of cancer cells in solid tumors with the self-renewal, differentiation and tumorigenic ability are responsible for tumor initiation, progression, recurrence, metastasis, and resistance to current treatments. Therefore, eradication of CSCs is very vital to cure cancer. Here, we first isolated and identified sphere-forming cells in tumor tissue from four GC patients and then analyzed T cell responses induced by monocyte-derived dendritic cells (DCs) loaded with total mRNA of sphere-forming cells in terms of interferon-gamma (IFN-γ) gene expression and specific cytotoxicity. Spheroid colonies were formed in serum-free media. Sphere-forming cells dissociated from tumorspheres heterogeneously expressed CD44, CD54, and epithelial cell adhesion molecule (EpCAM) markers and generated one tumor in nude mice. These results demonstrated that gastric CSCs were enriched in tumorspheres. Cytokine-matured DCs loaded with mRNA of sphere-forming cells were able to induce IFN-γ gene expression in T-lymphocytes after a 12-day co-culture. mRNA level of IFN-γ gene in these lymphocytes was more highly expressed compared to stimulated T-lymphocytes by DCs transfected with normal tissue (6.4-9.39 folds). Cytotoxic activity of primed T-lymphocytes with antigens of sphere-forming cells was significantly higher than normal tissue antigens and mock DCs (P ≤ 0.0001). Taken together, DCs loaded with mRNA of sphere-forming cells that elicit effectively specific T cell-mediated immune responses in vitro, may be considered as a promising therapeutic vaccination in GC patients in future.

Biomimetic Nanoparticle Vaccines for Cancer Therapy

It is currently understood that, in order for a tumor to successfully grow, it must evolve means of evading immune surveillance. In the past several decades, researchers have leveraged increases in our knowledge of tumor immunology to develop therapies capable of augmenting endogenous immunity and eliciting strong antitumor responses. In particular, the goal of anticancer vaccination is to train the immune system to properly utilize its own resources in the fight against cancer. Although attractive in principle, there are currently only limited examples of anticancer vaccines that have been successfully translated to the clinic. Recently, there has been a significant push towards the use of nanotechnology for designing vaccine candidates that exhibit enhanced potency and specificity. In this progress report, we discuss recent developments in the field of anticancer nanovaccines. By taking advantage of the flexibility offered by nanomedicine to purposefully program immune responses, this new generation of vaccines has the potential to address many of the hurdles facing traditional platforms. A specific emphasis is placed on the emergence of cell membrane-coated nanoparticles, a novel biomimetic platform that can be used to generate personalized nanovaccines that elicit strong, multi-antigenic antitumor responses.

Chemokines and Chemokine Receptors: Orchestrating Tumor Metastasization

Metastasis still represents the primary cause of cancer morbidity and mortality worldwide. Chemokine signalling contributes to the overall process of cancer growth and metastasis, and their expression in both primary tumors and metastatic lesions correlate with prognosis. Chemokines promote tumor metastasization by directly supporting cancer cell survival and invasion, angiogenesis, and by indirectly shaping the pre-metastatic niches and antitumor immunity. Here, we will focus on the relevant chemokine/chemokine receptor axes that have been described to drive the metastatic process. We elaborate on their role in the regulation of tumor angiogenesis and immune cell recruitment at both the primary tumor lesions and the pre-metastatic foci. Furthermore, we also discuss the advantages and limits of current pharmacological strategies developed to target chemokine networks for cancer therapy.

TSR-033, a Novel Therapeutic Antibody Targeting LAG-3, Enhances T-Cell Function and the Activity of PD-1 Blockade In Vitro and In Vivo

Progressive upregulation of checkpoints on tumor-infiltrating lymphocytes promotes an immunosuppressive tumor microenvironment, severely compromising tumor immunity. Lymphocyte activation gene-3 (LAG-3) is a coinhibitory receptor associated with impaired T-cell function and is frequently coexpressed with programmed cell death protein-1 (PD-1) in the context of human cancers. Targeting LAG-3 in conjunction with PD-1 thus represents a strategy to amplify and broaden the therapeutic impact of PD-1 blockade alone. We have generated a high affinity and selective humanized monoclonal IgG4 antibody, TSR-033, which binds human LAG-3 and serves as a functional antagonist, enhancing in vitro T-cell activation both in mixed lymphocyte reactions and staphylococcal enterotoxin B-driven stimulation assays. In a humanized mouse non-small cell lung carcinoma model, TSR-033 boosted the antitumor efficacy of PD-1 monotherapy, with a concomitant increase in immune activation. Analogous studies in a murine syngeneic tumor model using surrogate antibodies demonstrated significant synergy between LAG-3 and PD-1 blockade-combination treatment led to a marked improvement in therapeutic efficacy, increased T-cell proliferation, IFNγ production, and elicited durable immunologic memory upon tumor rechallenge. Taken together, the pharmacologic activity of TSR-033 demonstrates that it is a potent anti-LAG-3 therapeutic antibody and supports its clinical investigation in cancer patients.

A Self-Delivery Chimeric Peptide for Photodynamic Therapy Amplified Immunotherapy

In this paper, a self-delivery chimeric peptide PpIX-PEG₈ -KVPRNQDWL is designed for photodynamic therapy (PDT) amplified immunotherapy against malignant melanoma. After self-assembly into nanoparticles (designated as PPMA), this self-delivery system shows high drug loading rate, good dispersion, and stability as well as an excellent capability in producing reactive oxygen species (ROS). After cellular uptake, the ROS generated under light irradiation could induce the apoptosis and/or necrosis of tumor cells, which would subsequently stimulate the anti-tumor immune response. On the other hand, the melanoma specific antigen (KVPRNQDWL) peptide could also activate the specific cytotoxic T cells for anti-tumor immunity. Compared to immunotherapy alone, the combined photodynamic immunotherapy exhibits significantly enhanced inhibition of melanoma growth. Both in vitro and in vivo investigations confirm that PDT of PPMA has a positive effect on anti-tumor immune response. This self-delivery system demonstrates a great potential of this PDT amplified immunotherapy strategy for advanced or metastatic tumor treatment.

Current State of Dendritic Cell-Based Immunotherapy: Opportunities for in vitro Antigen Loading of Different DC Subsets?

Dendritic cell (DC) based cancer immunotherapy aims at the activation of the immune system, and in particular tumor-specific cytotoxic T lymphocytes (CTLs) to eradicate the tumor. DCs represent a heterogeneous cell population, including conventional DCs (cDCs), consisting of cDC1s, cDC2s, plasmacytoid DCs (pDCs), and monocyte-derived DCs (moDCs). These DC subsets differ both in ontogeny and functional properties, such as the capacity to induce CD4+ and CD8+ T-cell activation. MoDCs are most frequently used for vaccination purposes, based on technical aspects such as availability and in vitro expansion. However, whether moDCs are superior over other DC subsets in inducing anti-tumor immune responses, is unknown, and likely depends on tumor type and composition of the tumor microenvironment. In this review, we discuss cellular aspects essential for DC vaccination efficacy, and the most recent findings on different DC subsets that could be used for DC-based cancer immunotherapy. This can prove valuable for the future design of more effective DC vaccines by choosing different DC subsets, and sheds light on the working mechanism of DC immunotherapy.

RNA-Based Immunostimulatory Liposomal Spherical Nucleic Acids as Potent TLR7/8 Modulators

Immunostimulatory spherical nucleic acids (IS-LSNAs) comprised of RNA selective for toll-like receptors (TLRs) 7/8 are synthesized and characterized. These structures consist of liposomal cores functionalized with a dense shell of RNA inserted into the wall of the lipid core via hydrophobic cholesterol moieties. IS-LSNAs potently activate TLR7/8 via NF-κΒ signaling in reporter cell lines and in primary immune cells as evidenced by cytokine production and the upregulation of costimulatory receptors. Importantly, they are preferentially taken up by plasmacytoid dendritic cells, an observation that makes them potentially useful for immunotherapy. In addition, these structures contain a core that can be loaded with antigens and used to prime T cells. In this regard, it is shown that dendritic cells treated with IS-SNAs loaded with ovalbumin peptide can prime ova specific CD8⁺ T cells. In addition to introducing the first IS-LSNAs consisting of RNA, these experiments show that one can facilitate an antigen-specific T cell response greater than that of free or cationic lipid-transfected RNA of the same sequence selective for TLR7/8. This work points toward the promise of using IS-LSNAs comprised of RNA as potent and highly tunable TLR-specific agents for the development of vaccines and other pharmaceuticals that require selective immunomodulation.

Does the Immunocompetent Status of Cancer Patients Have an Impact on Therapeutic DC Vaccination Strategies?

Although different types of therapeutic vaccines against established cancerous lesions in various indications have been developed since the 1990s, their clinical benefit is still very limited. This observed lack of effectiveness in cancer eradication may be partially due to the often deficient immunocompetent status of cancer patients, which may facilitate tumor development by different mechanisms, including immune evasion. The most frequently used cellular vehicle in clinical trials are dendritic cells (DCs), thanks to their crucial role in initiating and directing immune responses. Viable vaccination options using DCs are available, with a positive toxicity profile. For these reasons, despite their limited therapeutic outcomes, DC vaccination is currently considered an additional immunotherapeutic option that still needs to be further explored. In this review, we propose potential actions aimed at improving DC vaccine efficacy by counteracting the detrimental mechanisms recognized to date and implicated in establishing a poor immunocompetent status in cancer patients.

Harnessing the Induction of CD8+ T-Cell Responses Through Metabolic Regulation by Pathogen-Recognition-Receptor Triggering in Antigen Presenting Cells

Cytotoxic CD8⁺ T-cells are key players of the immune responses against viruses. During the priming of a CD8⁺ T-cell response, the activation of a naïve T-cell by a professional antigen presenting cell (APC) involves the induction of various intracellular and metabolic pathways. The modulation of these pathways at the level of APCs or T-cells offers great potential to enhance the induction of robust effector cells and the generation of long-lived memory cells. On the one hand, signaling through pathogen recognition receptors (PRRs) expressed by APCs can greatly influence T-cell priming, and the potential of several PRR ligands as adjuvants are being studied. On the other hand, the engagement of several metabolic processes, at play in APCs and T-cells upon stimulation, implies that modulating cellular metabolism can impact on priming efficacy. Here, we review recent efforts to understand the interplay between PRR mediated signaling and metabolic pathway modulation in this context, through three examples: interplay between TLR4 and fatty acid metabolism, between TLR9 and IDO, and between STING and autophagy. These initial works highlight the potential for harnessing the induction of antiviral CD8⁺ T-cell responses using synergistic modulation of metabolic and PRR pathways.

Decrease in Intracellular Perforin Levels and IFN-γ Production in Human CD8+ T Cell Line following Long-Term Exposure to Asbestos Fibers

Although the tumorigenicity of asbestos, which is thought to cause mesothelioma, has been clarified, its effect on antitumor immunity requires further investigation. We previously reported a decrease in the percentage of perforin⁺ cells of stimulated CD8⁺ lymphocytes derived from patients with malignant mesothelioma. Therefore, we examined the effects of long-term exposure to asbestos on CD8⁺ T cell functions by comparing long-term cultures of the human CD8⁺ T cell line EBT-8 with and without exposure to chrysotile (CH) asbestos as an in vitro model. Exposure to CH asbestos at 5 μg/ml or 30 μg/ml did not result in a decrease in intracellular granzyme B in EBT-8 cells. In contrast, the percentage of perforin⁺ cells decreased at both doses of CH exposure. CH exposure at 30 μg/ml did not suppress degranulation following stimulation with antibodies to CD3. Secreted production of IFN-γ stimulated via CD3 decreased by CH exposure at 30 μg/ml, although the percentage of IFN-γ⁺ cells induced by PMA/ionomycin did not decrease. These results indicate that long-term exposure to asbestos can potentially suppress perforin levels and the production of IFN-γ in human CD8⁺ T cells.

Fluorine-19 MRI for detection and quantification of immune cell therapy for cancer

Over the past two decades, immune cell therapy has emerged as a potent treatment for multiple cancers, first through groundbreaking leukemia therapy, and more recently, by tackling solid tumors. Developing successful therapeutic strategies using live cells could benefit from the ability to rapidly determine their in vivo biodistribution and persistence. Assaying cell biodistribution is unconventional compared to traditional small molecule drug pharmacokinetic readouts used in the pharmaceutical pipeline, yet this information is critical towards understanding putative therapeutic outcomes and modes of action. Towards this goal, efforts are underway to visualize and quantify immune cell therapy in vivo using advanced magnetic resonance imaging (MRI) techniques. Cell labeling probes based on perfluorocarbon nanoemulsions, paired with fluorine-19 MRI detection, enables background-free quantification of cell localization and survival. Here, we highlight recent preclinical and clinical uses of perfluorocarbon probes and ¹⁹F MRI for adoptive cell transfer (ACT) studies employing experimental T lymphocytes, NK, PBMC, and dendritic cell therapies. We assess the forward looking potential of this emerging imaging technology to aid discovery and preclinical phases, as well as clinical trials. The limitations and barriers towards widespread adoption of this technology, as well as alternative imaging strategies, are discussed.

Dendritic cells cross-talk with tumour antigen-specific CD8+ T cells, Vγ9γδT cells and Vα24NKT cells in patients with glioblastoma multiforme and in healthy donors

The finding that dendritic cells (DCs) orchestrate innate and adaptive immune responses has stimulated research on harnessing DCs for developing more effective vaccines for DC therapy. The expression of cytomegalovirus (CMV) antigens in glioblastoma multiforme (GBM) presents a unique opportunity to target these viral proteins for tumour immunotherapy. Here, we demonstrate that Vγ9γδT cells, innate immune cells activated by zoledronate (Z) and Vα24 natural killer (Vα24NK) cells, innate/adaptive immune cells activated by α‐galactosylceramide (G) can link innate and adaptive immunities through cross‐talk with interferon (IFN) DCs from patients with glioblastoma multiforme (GBM) and healthy donors in a manner that can amplify the activation and proliferation of CMVpp65‐specific CD8⁺ T cells. The IFN DCs derived from patients with GBM used in this study express lower levels of programmed cell death ligand (PD)‐L1 and PD‐L2 and higher levels of C‐C receptor 7 (CCR7) than the most commonly used mature interleukin (IL)‐4 DCs. The expression level of programmed cell death 1 (PD‐1) on CD8⁺ T cells, including CMVpp65‐specific CD8⁺ T cells, expanded by IFN DCs pulsed with the CMVpp65‐peptide and Z plus G (IFN DCs/P+Z+G), was lower than that expanded by IFN DCs pulsed with the peptide alone (IFN DCs/P). Multi‐functional T cells, including human leucocyte antigen (HLA)‐A*0201‐restricted CMVpp65‐specific CD8⁺ T cells, Vγ9γδT cells and Vα24NKT cells, efficiently kill the HLA‐A*0201‐positive GBM cell line expressing CMVpp65 protein (T98G). These findings indicate that DC therapy using IFN DCs/P+Z+G and/or CTL therapy using CMVpp65‐specific CD8⁺ T cells expanded by IFN DCs/P+Z+G may lead to a good clinical outcome for patients with GBM.

Combined encapsulation of a tumor antigen and immune cells using a self-assembling immunostimulatory DNA hydrogel to enhance antigen-specific tumor immunity

Our previous study demonstrated that the incorporation of a tumor antigen into a self-assembling DNA hydrogel, comprised of a DNA containing un-methylated cytosine-phosphate-guanine (CpG) dinucleotides (CpG DNA), efficiently induced antigen-specific tumor immunity after intra-tumoral injection into tumor-bearing mice. We hypothesized that the additional incorporation of immune cells, the target for the antigen and immunostimulatory CpG DNA, would increase the antitumor response. To prove this, immune cells were also encapsulated into the CpG DNA hydrogel and delivered along with the antigen. Mouse dendritic DC2.4 cells maintained their form even after incorporation into the DNA hydrogel. The incorporation of mouse macrophage-like J774.1 cells and RAW264.7 cells into CpG DNA hydrogel did not significantly affect their viability. J774.1, RAW264.7, DC2.4, and mouse bone marrow-derived dendritic cells (BMDCs) were efficiently activated when incorporated into the CpG DNA hydrogel. The CpG DNA hydrogel incorporated with both the tumor antigen and BMDCs effectively induced antigen-specific immune responses, and retarded tumor growth following intradermal administration before and after tumor inoculation without severe local and systemic adverse events. These data indicate that the combined delivery of a tumor antigen and immune cells using an immunostimulatory CpG DNA hydrogel is effective in inducing antigen-specific antitumor immunity.

CD40L coding oncolytic adenovirus allows long-term survival of humanized mice receiving dendritic cell therapy

Dendritic cells (DCs) are crucial players in promoting immune responses. Logically, adoptive DC therapy is a promising approach in cancer immunotherapy. One of the major obstacles in cancer immunotherapy in general is the immunosuppressive tumor microenvironment, which hampers the maturation and activation of DCs. Therefore, human clinical outcomes with DC therapy alone have been disappointing. In this study, we use fully serotype 3 oncolytic adenovirus Ad3-hTERT-CMV-hCD40L, expressing human CD40L, to modulate the tumor microenvironment with subsequently improved function of DCs. We evaluated the synergistic effects of Ad3-hTERT-CMV-hCD40L and DCs in the presence of human peripheral blood mononuclear cells ex vivo and in vivo. Tumors treated with Ad3-hTERT-CMV-hCD40L and DCs featured greater antitumor effect compared with unarmed virus or either treatment alone. 100% of humanized mice survived to the end of the experiment, while mice in all other groups died by day 88. Moreover, adenovirally-delivered CD40L induced activation of DCs, leading to induction of Th1 immune responses. These results support clinical trials with Ad3-hTERT-CMV-hCD40L in patients receiving DC therapy.

A novel function of API5 (apoptosis inhibitor 5), TLR4-dependent activation of antigen presenting cells

Dendritic cell (DC)-based vaccines are recognized as a promising immunotherapeutic strategy against cancer. Various adjuvants are often incorporated to enhance the modest immunogenicity of DC vaccines. More specifically, many of the commonly used adjuvants are derived from bacteria. In the current study, we evaluate the use of apoptosis inhibitor 5 (API5), a damage-associated molecular pattern expressed by many human cancer cells, as a novel DC vaccine adjuvant. We showed that API5 can prompt activation and maturation of DCs and activate NFkB by stimulating the Toll-like receptor signaling pathway. We also demonstrated that vaccination with API5-treated DCs pulsed with OVA, E7, or AH1-A5 peptides led to the generation of OVA, E7, or AH1-A5-specific CD8 + T cells and memory T cells, which is associated with long term tumor protection and antitumor effects in mice, against EG.7, TC-1, and CT26 tumors. Additionally, we determined that API5-mediated DC activation and immune stimulation are dependent on TLR4. Lastly, we showed that the API5 protein sequence fragment that is proximal to its leucine zipper motif is responsible for the adjuvant effects exerted by API5. Our data provide evidence that support the use of API5 as a promising adjuvant for DC-based therapies, which can be applied in combination with other cancer therapies. Most notably, our results further support the continued investigation of human-based adjuvants.

The Sulfated Polysaccharides of Brown Algae and Products of Their Enzymatic Transformation as Potential Vaccine Adjuvants

The review is devoted to critical analysis of literature data, deal with effects and mechanisms of action of sulfated polysaccharides (PSs) – fucoidans from brown algae and products of their enzymatic transformation as potential adjuvants for enhancement of anti-infective and antitumor immune response. Numerous experimental data indicate that sulfated PSs demonstrate properties of vaccine adjuvants. Application perspectiveness of fucoidans as vaccine adjuvants is defined by their high biocompatibility, low-toxicity, safety and good tolerance by macroorganism, and also mechanisms of their immunomodulatory action. In particular, fucoidans are agonists of receptors of innate immunity and strong inducers of cellular and humoral immune response. At presenting the data of structural - functional interrelations, attention focused to the defining role of degree of sulfation, uronic acids and polyphenols contents, and also molecular mass in actions of fucoidans to innate and adaptive immunity cells. Insufficiency of literary data on studying of correlation of structure – physicochemical characteristics with adjuvanticities of the sulfated PSs, and also the problem of standardization of their active fractions are noted. Special attention is paid to the analysis of immunomodulatory and adjuvant activity of fucoidan oligosaccharides. Presented here results of experimental trial indicate that, despite the difficulties due to preparation of highly purified structurally characterized fractions and complex structure of fucoidans, these substances can be used as safe and effective adjuvants in vaccines against various pathogens including viruses, and also in antitumor vaccines.