Dendritic cell-based therapeutic cancer vaccines: past, present and future

Enhancing Dendritic Cell Cancer Vaccination: The Synergy of Immune Checkpoint Inhibitors in Combined Therapies

Dendritic cell (DC) cancer vaccines are a promising therapeutic approach, leveraging the immune system to fight tumors. These vaccines utilize DCs' ability to present tumor-associated antigens to T cells, triggering a robust immune response. DC vaccine development has progressed through three generations. The first generation involved priming DCs with tumor-associated antigens or messenger RNA outside the body, showing limited clinical success. The second generation improved efficacy by using cytokine mixtures and specialized DC subsets to enhance immunogenicity. The third generation used blood-derived DCs to elicit a stronger immune response. Clinical trials indicate that cancer vaccines have lower toxicity than traditional cytotoxic treatments. However, achieving significant clinical responses with DC immunotherapy remains challenging. Combining DC vaccines with immune checkpoint inhibitors (ICIs), such as anticytotoxic T-lymphocyte Antigen 4 and antiprogrammed death-1 antibodies, has shown promise by enhancing T-cell responses and improving clinical outcomes. These combinations can transform non-inflamed tumors into inflamed ones, boosting ICIs' efficacy. Current research is exploring new checkpoint targets like LAG-3, TIM-3, and TIGIT, considering their potential with DC vaccines. Additionally, engineering T cells with chimeric antigen receptors or T-cell receptors could further augment the antitumor response. This comprehensive strategy aims to enhance cancer immunotherapy, focusing on increased efficacy and improved patient survival rates.

Current status and future of cancer vaccines: A bibliographic study

Background

Cancer vaccines are an important component of tumour immunotherapy. An increasing number of studies have shown that cancer vaccines have considerable clinical benefits. With the development of tumour precision medicine, cancer vaccines have become important because of their individualised targeting effects. However, few bibliometric studies have conducted comprehensive systematic reviews in this field. This study aimed to assess the scientific output and trends in cancer vaccine research from a global perspective.

Methods

We collected publications on cancer vaccines from the Web of Science Core Collection database, which was limited to articles and reviews in English. Microsoft Excel, VOS Viewer, and CiteSpace V were used for quantitative and visual analyses.

Results

A total of 7807 articles were included. From 1991 to 2022, the number of publications increased annually. The United States had the highest number of articles published in this field (48.28 %), the highest citation frequency (183,964 times), and the highest H-index (182). The National Institutes of Health topped the list with 476 articles. Schlom J had the highest number of published articles (128) and was the main investigator in this field. The journal, Cancer Immunology Immunotherapy, had published the highest number of articles in related fields. In recent years, tumour microenvironment, immune checkpoint inhibitors, particle vaccines, tumour antigens, and dendritic cells have become research hotspots related to cancer vaccines.

Conclusion

Cancer vaccines are a popular research topic in the field of tumour immunotherapy. Related research and publications will enter a boom stage. "Immune checkpoint inhibitors", "tumour microenvironment" and "dendritic cells" may become future research hotspots, while "T-cell suppressor" is a potential puzzle to be solved.

Targeting the pericyte antigen DLK1 with an alpha type-1 polarized dendritic cell vaccine results in tumor vascular modulation and protection against colon cancer progression

Despite the availability of various treatment options, colorectal cancer (CRC) remains a significant contributor to cancer-related mortality. Current standard-of-care interventions, including surgery, chemotherapy, and targeted agents like immune checkpoint blockade and anti-angiogenic therapies, have improved short-term patient outcomes depending on disease stage, but survival rates with metastasis remain low. A promising strategy to enhance the clinical experience with CRC involves the use of dendritic cell (DC) vaccines that incite immunity against tumor-derived blood vessels, which are necessary for CRC growth and progression. In this report, we target tumor-derived pericytes expressing DLK1 with a clinically-relevant alpha type-1 polarized DC vaccine (αDC1) in a syngeneic mouse model of colorectal cancer. Our pre-clinical data demonstrate the αDC1 vaccine's ability to induce anti-tumor effects by facilitating cytotoxic T lymphocyte activity and ablating the tumor vasculature. This work, overall, provides a foundation to further interrogate immune-mediated mechanisms of protection in order to help devise efficacious αDC1-based strategies for patients with CRC.

Prospective, randomized, double-blind phase 2B trial of the TLPO and TLPLDC vaccines to prevent recurrence of resected stage III/IV melanoma: a prespecified 36-month analysis

BACKGROUND

The tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine is made by ex vivo priming matured autologous dendritic cells (DCs) with yeast cell wall particles (YCWPs) loaded with autologous tumor lysate (TL). The tumor lysate, particle only (TLPO) vaccine uses autologous TL-loaded YCWPs coated with silicate for in vivo DC loading. Here we report the 36-month prespecified analyses of this prospective, randomized, double-blind trial investigating the ability of the TLPO and TLPLDC (±granulocyte-colony stimulating factor (G-CSF)) vaccines to prevent melanoma recurrence in high-risk patients.

METHODS

Patients with clinically disease-free stage III/IV melanoma were randomized 2:1 initially to TLPLDC versus placebo (n=124) and subsequently TLPO versus TLPLDC (n=63). All patients were randomized and blinded; however, the placebo control arm was replaced in the second randomization scheme with another novel vaccine; some analyses in this paper therefore reflect a combination of the two randomization schemes. Patients receiving the TLPLDC vaccine were further divided by their method of DC harvest (with or without G-CSF pretreatment); this was not randomized. The use of standard of care checkpoint inhibitors was not stratified between groups. Safety was assessed and Kaplan-Meier and log-rank analyses compared disease-free (DFS) and overall survival (OS).

RESULTS

After combining the two randomization processes, a total of 187 patients were allocated between treatment arms: placebo (n=41), TLPLDC (n=103), or TLPO (n=43). The allocation among arms created by the addition of patients from the two separate randomization schemes does not reflect concurrent randomization among all treatment arms. TLPLDC was further divided by use of G-CSF in DC harvest: no G-CSF (TLPLDC) (n=47) and with G-CSF (TLPLDC+G) (n=56). Median follow-up was 35.8 months. Only two patients experienced a related adverse event ≥grade 3, one each in the TLPLDC+G and placebo arms. DFS was 27.2% (placebo), 55.4% (TLPLDC), 22.9% (TLPLDC+G), and 60.9% (TLPO) (p<0.001). OS was 62.5% (placebo), 93.6% (TLPLDC), 57.7% (TLPLDC+G), and 94.6% (TLPO) (p=0.002).

CONCLUSIONS

The TLPO and TLPLDC (without G-CSF) vaccines were associated with improved DFS and OS in this clinical trial. Given production and manufacturing advantages, the efficacy of the TLPO vaccine will be confirmed in a phase 3 trial.

TRIAL REGISTRATION NUMBER

NCT02301611.

Therapeutic applications of nanobiotechnology

Nanobiotechnology, as a novel and more specialized branch of science, has provided a number of nanostructures such as nanoparticles, by utilizing the methods, techniques, and protocols of other branches of science. Due to the unique features and physiobiological characteristics, these nanostructures or nanocarriers have provided vast methods and therapeutic techniques, against microbial infections and cancers and for tissue regeneration, tissue engineering, and immunotherapies, and for gene therapies, through drug delivery systems. However, reduced carrying capacity, abrupt and non-targeted delivery, and solubility of therapeutic agents, can affect the therapeutic applications of these biotechnological products. In this article, we explored and discussed the prominent nanobiotechnological methods and products such as nanocarriers, highlighted the features and challenges associated with these products, and attempted to conclude if available nanostructures offer any scope of improvement or enhancement. We aimed to identify and emphasize the nanobiotechnological methods and products, with greater prospect and capacity for therapeutic improvements and enhancements. We found that novel nanocarriers and nanostructures, such as nanocomposites, micelles, hydrogels, microneedles, and artificial cells, can address the associated challenges and inherited drawbacks, with help of conjugations, sustained and stimuli-responsive release, ligand binding, and targeted delivery. We recommend that nanobiotechnology, despite having few challenges and drawbacks, offers immense opportunities that can be harnessed in delivering quality therapeutics with precision and prediction. We also recommend that, by exploring the branched domains more rigorously, bottlenecks and obstacles can also be addressed and resolved in return.

Development and validation of a tumor immune cell infiltration-related gene signature for recurrence prediction by weighted gene co-expression network analysis in prostate cancer

Introduction: Prostate cancer (PCa) is the second most common malignancy in men. Despite multidisciplinary treatments, patients with PCa continue to experience poor prognoses and high rates of tumor recurrence. Recent studies have shown that tumor-infiltrating immune cells (TIICs) are associated with PCa tumorigenesis.

Methods: The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets were used to derive multi-omics data for prostate adenocarcinoma (PRAD) samples. The CIBERSORT algorithm was used to calculate the landscape of TIICs. Weighted gene co-expression network analysis (WGCNA) was performed to determine the candidate module most significantly associated with TIICs. LASSO Cox regression was applied to screen a minimal set of genes and construct a TIIC-related prognostic gene signature for PCa. Then, 78 PCa samples with CIBERSORT output p-values of less than 0.05 were selected for analysis. WGCNA identified 13 modules, and the MEblue module with the most significant enrichment result was selected. A total of 1143 candidate genes were cross-examined between the MEblue module and active dendritic cell-related genes.

Results: According to LASSO Cox regression analysis, a risk model was constructed with six genes (STX4, UBE2S, EMC6, EMD, NUCB1 and GCAT), which exhibited strong correlations with clinicopathological variables, tumor microenvironment context, antitumor therapies, and tumor mutation burden (TMB) in TCGA-PRAD. Further validation showed that the UBE2S had the highest expression level among the six genes in five different PCa cell lines.

Discussion: In conclusion, our risk-score model contributes to better predicting PCa patient prognosis and understanding the underlying mechanisms of immune responses and antitumor therapies in PCa.

A bird's eye view on the role of dendritic cells in SARS-CoV-2 infection: Perspectives for immune-based vaccines

Coronavirus disease-19 (COVID-19) is a complex disorder caused by the pandemic diffusion of a novel coronavirus named SARS-CoV-2. Clinical manifestations vary from silent infection to severe pneumonia, disseminated thrombosis, multi-organ failure, and death. COVID-19 pathogenesis is still not fully elucidated, while increasing evidence suggests that disease phenotypes are strongly related to the virus-induced immune system's dysregulation. Indeed, when the virus-host cross talk is out of control, the occurrence of an aberrant systemic inflammatory reaction, named "cytokine storm," leads to a detrimental impairment of the adaptive immune response. Dendritic cells (DCs) are the most potent antigen-presenting cells able to support innate immune and promote adaptive responses. Besides, DCs play a key role in the anti-viral defense. The aim of this review is to focus on DC involvement in SARS-CoV-2 infection to better understand pathogenesis and clinical behavior of COVID-19 and explore potential implications for immune-based therapy strategies.

Modeling codelivery of CD73 inhibitor and dendritic cell-based vaccines in cancer immunotherapy

Dendritic cells (DCs) are the dominant class of antigen-presenting cells in humans; therefore, a range of DC-based approaches have been established to promote an immune response against cancer cells. The efficacy of DC-based immunotherapeutic approaches is markedly affected by the immunosuppressive factors related to the tumor microenvironment, such as adenosine. In this paper, based on immunological theories and experimental data, a hybrid model is designed that offers some insights into the effects of DC-based immunotherapy combined with adenosine inhibition. The model combines an individual-based model for describing tumor-immune system interactions with a set of ordinary differential equations for adenosine modeling. Computational simulations of the proposed model clarify the conditions for the onset of a successful immune response against cancer cells. Global and local sensitivity analysis of the model highlights the importance of adenosine blockage for strengthening effector cells. The model is used to determine the most effective suppressive mechanism caused by adenosine, proper vaccination time, and the appropriate time interval between injections.

Bio-vehicles of cytotoxic drugs for delivery to tumor specific targets for cancer precision therapy

Abnormal structural and molecular changes in malignant tissues were thoroughly investigated and utilized to target tumor cells, hence rescuing normal healthy tissues and lowering the unwanted side effects as non-specific cytotoxicity. Various ligands for cancer cell specific markers have been uncovered and inspected for directional delivery of the anti-cancer drug to the tumor site, in addition to diagnostic applications. Over the past few decades research related to the ligand targeted therapy (LTT) increased tremendously aiming to treat various pathologies, mainly cancers with well exclusive markers. Malignant tumors are known to induce elevated levels of a variety of proteins and peptides known as cancer "markers" as certain antigens (e.g., Prostate specific membrane antigen "PSMA", carcinoembryonic antigen "CEA"), receptors (folate receptor, somatostatin receptor), integrins (Integrin αvβ3) and cluster of differentiation molecules (CD13). The choice of an appropriate marker to be targeted and the design of effective ligand-drug conjugate all has to be carefully selected to generate the required therapeutic effect. Moreover, since some tumors express aberrantly high levels of more than one marker, some approaches investigated targeting cancer cells with more than one ligand (dual or multi targeting). We aim in this review to report an update on the cancer-specific receptors and the vehicles to deliver cytotoxic drugs, including recent advancements on nano delivery systems and their implementation in targeted cancer therapy. We will discuss the advantages and limitations facing this approach and possible solutions to mitigate these obstacles. To achieve the said aim a literature search in electronic data bases (PubMed and others) using keywords "Cancer specific receptors, cancer specific antibody, tumor specific peptide carriers, cancer overexpressed proteins, gold nanotechnology and gold nanoparticles in cancer treatment" was carried out.

Overcoming Chemoimmunotherapy-Induced Immunosuppression by Assemblable and Depot Forming Immune Modulating Nanosuspension

The deficiency of antigen-specific T cells and the induction of various treatment-induced immunosuppressions still limits the clinical benefit of cancer immunotherapy. Although the chemo-immunotherapy adjuvanted with Toll-like receptor 7/8 agonist (TLR 7/8a) induces immunogenic cell death (ICD) and in situ vaccination effect, indoleamine 2,3-dioxygenase (IDO) is also significantly increased in the tumor microenvironment (TME) and tumor-draining lymph node (TDLN), which offsets the activated antitumor immunity. To address the treatment-induced immunosuppression, an assemblable immune modulating suspension (AIMS) containing ICD inducer (paclitaxel) and supra-adjuvant (immune booster; R848 as a TLR 7/8a, immunosuppression reliever; epacadostat as an IDO inhibitor) is suggested and shows that it increases cytotoxic T lymphocytes and relieves the IDO-related immunosuppression (TGF-β, IL-10, myeloid-derived suppressor cells, and regulatory T cells) in both TME and TDLN, by the formation of in situ depot in tumor bed as well as by the efficient migration into TDLN. Local administration of AIMS increases T cell infiltration in both local and distant tumors and significantly inhibits the metastasis of tumors to the lung. Reverting treatment-induced secondary immunosuppression and reshaping "cold tumor" into "hot tumor" by AIMS also increases the response rate of immune checkpoint blockade therapy, which promises a new nanotheranostic strategy in cancer immunotherapy.

Fusion Protein Vaccine Based on Ag85B and STEAP1 Induces a Protective Immune Response against Prostate Cancer

(1) Background: There are currently limited treatments for castration-resistant prostate cancer. Immunotherapy involving Sipuleucel-T has increasingly drawn attention for prostate cancer management. BCG plays a vital role in treating bladder cancer, mainly by inducing immune activation, but is rarely used for prostate cancer. (2) Methods: The TCGA database, PCR, and Western blotting were used to analyze the expression of STEAP1 in mouse and human tissues. Then, we constructed a fusion protein vaccine with Mycobacterium tuberculosis Ag85B and three repeated octapeptide epitopes of a six-transmembrane epithelial antigen of the prostate 1 (STEAP1_186-193), Ag85B-3×STEAP1_186-193. The uptake of the fusion protein vaccine by DCs was evaluated by confocal microscopy, and DC markers were detected using flow cytometry after incubation with the fusion protein. The immune response against prostate cancer was evaluated by the LDH assay and xenografts in vitro and in vivo. Then, the tumor microenvironment was determined using IHC and ELISA. In addition, the epitope was mutated using CRISPR-Cas9 to illustrate that the fusion protein elicited immunization against STEAP1. (3) Results: The TCGA database analysis, PCR, and Western blotting showed that STEAP1 was highly expressed in human and murine prostate cancer. After the uptake of the purified fusion protein vaccine by DCs, CD11c, CD80, CD86, and MHC II were upregulated and triggered a cytotoxic T lymphocyte (CTL) response against TRAMP-C1 and RM1 cells in vitro. Furthermore, the fusion protein vaccine inhibited tumor growth and improved the tumor microenvironment in vivo, with more CD3⁺ cells and fewer FOXP3⁺ cells in the tumor. Serum IFN-γ and IL-2 were significantly higher than in the control group, while IL-4 expression was lower, indicating that the fusion protein vaccine activated Th1 immunity. The immune response against prostate cancer was greatly suppressed when the antigen targets were knocked out using CRISPR-Cas9. (4) Conclusion: In summary, our results provide the first evidence that a vaccine based on a fusion protein consisting of Ag85B and a prostate cancer octapeptide epitope with complete Freund’s adjuvant (CFA), triggers a robust immune response and inhibits tumor growth in murine prostate cancer.

The subtle interplay between gamma delta T lymphocytes and dendritic cells: is there a role for a therapeutic cancer vaccine in the era of combinatorial strategies?

Human gamma delta (γδ) T cells represent heterogeneous subsets of unconventional lymphocytes with an HLA-unrestricted target cell recognition. γδ T cells display adaptive clonally restricted specificities coupled to a powerful cytotoxic function against transformed/injured cells. Dendritic cells (DCs) are documented to be the most potent professional antigen-presenting cells (APCs) able to induce adaptive immunity and support the innate immune response independently from T cells. Several data show that the cross-talk of γδ T lymphocytes with DCs can play a crucial role in the orchestration of immune response by bridging innate to adaptive immunity. In the last decade, DCs, as well as γδ T cells, have been of increasing clinical interest, especially as monotherapy for cancer immunotherapy, even though with unpredictable results mainly due to immune suppression and/or tumor-immune escape. For these reasons, new vaccine strategies have to be explored to reach cancer immunotherapy's full potential. The effect of DC-based vaccines on γδ T cell is less extensively investigated, and a combinatorial approach using DC-based vaccines with γδ T cells might promote a strong synergy for long-term tumor control and protection against escaping tumor clones. Here, we discuss the therapeutic potential of the interaction between DCs and γδ T cells to improve cancer vaccination. In particular, we describe the most relevant and updated evidence of such combinatorial approaches, including the use of Zoledronate, Interleukin-15, and protamine RNA, also looking towards future strategies such as CAR therapies.

Extracellular vesicles as antigen carriers for novel vaccination avenues

Antigen delivery has always been a challenge in scientific practice of vaccine formulation. Yet, mammalian extracellular vesicles (EVs) or bacterial membrane vesicles (MVs) provide an innovative avenue for safe and effective delivery of antigenic material. They include intrinsically loaded antigens from EV-secreting cells or extrinsically loaded antigens onto pre-formed vesicles. Interestingly, many studies shed light on potential novel anti-cancer vaccination immunotherapy for therapeutic applications from mammalian cell host-derived EVs, as well as conventional vaccination for prophylactic applications using bacterial cell-derived MVs against infectious diseases. Here, we discuss the rationale, status quo and potential for both vaccine applications using EVs.

Plant-based vaccines and cancer therapy: Where are we now and where are we going?

Therapeutic vaccines are an effective approach in cancer therapy for treating the disease at later stages. The Food and Drug Administration (FDA) recently approved the first therapeutic cancer vaccine, and further studies are ongoing in clinical trials. These are expected to result in the future development of vaccines with relatively improved efficacy. Several vaccination approaches are being studied in pre-clinical and clinical trials, including the generation of anti-cancer vaccines by plant expression systems.This approach has advantages, such as high safety and low costs, especially for the synthesis of recombinant proteins. Nevertheless, the development of anti-cancer vaccines in plants is faced with some technical obstacles.Herein, we summarize some vaccines that have been used in cancer therapy, with an emphasis on plant-based vaccines.

Immune Checkpoint Inhibitors in EGFR-Mutated NSCLC: Dusk or Dawn?

Although immune checkpoint inhibitors (ICIs) that target programmed cell death protein-1/programmed cell death ligand-1 axis have significantly shifted the treatment paradigm in advanced NSCLC, clinical benefits of these agents are limited in patients with EGFR-mutated NSCLC. Several predictive biomarkers (e.g., programmed cell death ligand-1 expression, tumor mutation burden), which have been validated in EGFR-wild type NSCLC, however, are not efficacious in EGFR-mutated tumors, suggesting the unique characteristics of tumor microenvironment of EGFR-mutated NSCLC. Here, we first summarized the clinical evidence on the efficacy of ICIs in patients with EGFR-mutated NSCLC. Then, the cancer immunogram features of EGFR-mutated NSCLC was depicted to visualize the state of cancer-immune system interactions, including tumor foreignness, tumor sensitivity to immune effectors, metabolism, general immune status, immune cell infiltration, cytokines, and soluble molecules. We further discussed the potential subpopulations with EGFR mutations that could benefit from ICI treatment. Lastly, we put forward future strategies to adequately maximize the efficacy of ICI treatment in patients with EGFR-mutated NSCLC in the upcoming era of combination immunotherapies.

Generated SecPen_NY-ESO-1_ubiquitin-pulsed dendritic cell cancer vaccine elicits stronger and specific T cell immune responses

Dendritic cell-based cancer vaccines (DC vaccines) have been proved efficient and safe in immunotherapy of various cancers, including melanoma, ovarian and prostate cancer. However, the clinical responses were not always satisfied. Here we proposed a novel strategy to prepare DC vaccines. In the present study, a fusion protein SNU containing a secretin-penetratin (SecPen) peptide, NY-ESO-1 and ubiquitin was designed and expressed. To establish the DC vaccine (DC-SNU), the mouse bone marrow-derived DCs (BMDCs) were isolated, pulsed with SNU and maturated with cytokine cocktail. Then peripheral blood mononuclear cells (PBMCs) from C57BL/6 mice inoculated intraperitoneally with DC-SNU were separated and cocultured with MC38/MC38^NY-ESO-1 tumor cells or DC vaccines. The results show that SNU was successfully expressed. This strategy made NY-ESO-1 entering cytoplasm of BMDCs more efficiently and degraded mainly by proteasome. As we expected, mature BMDCs expressed higher CD40, CD80 and CD86 than immature BMDCs. Thus, the PBMCs released more IFN-γ and TNF-α when stimulated with DC-SNU in vitro again. What's more, the PBMCs induced stronger and specific cytotoxicity towards MC38^NY-ESO-1 tumor cells. Given the above, it demonstrated that DC-SNU loaded with SecPen and ubiquitin-fused NY-ESO-1 could elicit stronger and specific T cell immune responses. This strategy can be used as a platform for DC vaccine preparation and applied to various cancers treatment.

Interleukin-1 as Innate Mediator of T Cell Immunity

The three-signal paradigm tries to capture how the innate immune system instructs adaptive immune responses in three well-defined actions: (1) presentation of antigenic peptides in the context of MHC molecules, which allows for a specific T cell response; (2) T cell co-stimulation, which breaks T cell tolerance; and (3) secretion of polarizing cytokines in the priming environment, thereby specializing T cell immunity. The three-signal model provides an empirical framework for innate instruction of adaptive immunity, but mainly discusses STAT-dependent cytokines in T cell activation and differentiation, while the multi-faceted roles of type I IFNs and IL-1 cytokine superfamily members are often neglected. IL-1α and IL-1β are pro-inflammatory cytokines, produced following damage to the host (release of DAMPs) or upon innate recognition of PAMPs. IL-1 activity on both DCs and T cells can further shape the adaptive immune response with variable outcomes. IL-1 signaling in DCs promotes their ability to induce T cell activation, but also direct action of IL-1 on both CD4+ and CD8+ T cells, either alone or in synergy with prototypical polarizing cytokines, influences T cell differentiation under different conditions. The activities of IL-1 form a direct bridge between innate and adaptive immunity and could therefore be clinically translatable in the context of prophylactic and therapeutic strategies to empower the formation of T cell immunity. Understanding the modalities of IL-1 activity during T cell activation thus could hold major implications for rational development of the next generation of vaccine adjuvants.

Analysis of tumor-immune dynamics in a delayed dendritic cell therapy model

We formulate a tumor-immune interaction model with a constant delay to capture the behavior following application of a dendritic cell therapy. The model is validated using experimental data from melanoma-induced mice. Through theoretical and numerical analyses, the model is shown to produce rich dynamics, such as a Hopf bifurcation and bistability. We provide thresholds for tumor existence and, in a special case, tumor elimination. Our work indicates a sensitivity in model outcomes to the immune response time. We provide a stability analysis for the high tumor equilibrium. For small delays in response, the tumor and immune system coexist at a low level. Large delays give rise to fatally high tumor levels. Our computational and theoretical work reveals that there exists an intermediate region of delay that generates complex oscillatory, even chaotic, behavior. The model then reflects uncertainty in treatment outcomes for varying initial tumor burdens, as well as tumor dormancy followed by uncontrolled growth to a lethal size, a phenomenon seen in vivo. Theoretical and computational analyses suggest efficacious treatments to use in conjunction with the dendritic cell vaccine. Additional analysis of a highly aggressive tumor additionally confirms the importance of representation with a time delay, as periodic solutions are strictly able to be generated when a delay is present.

Advances in epidermal growth factor receptor specific immunotherapy: lessons to be learned from armed antibodies

The epidermal growth factor receptor (EGFR) has been recognized as an important therapeutic target in oncology. It is commonly overexpressed in a variety of solid tumors and is critically involved in cell survival, proliferation, metastasis, and angiogenesis. This multi-dimensional role of EGFR in the progression and aggressiveness of cancer, has evolved from conventional to more targeted therapeutic approaches. With the advent of hybridoma technology and phage display techniques, the first anti-EGFR monoclonal antibodies (mAbs) (Cetuximab and Panitumumab) were developed. Due to major limitations including host immune reactions and poor tumor penetration, these antibodies were modified and used as guiding mechanisms for the specific delivery of readily available chemotherapeutic agents or plants/bacterial toxins, giving rise to antibody-drug conjugates (ADCs) and immunotoxins (ITs), respectively. Continued refinement of ITs led to deimmunization strategies based on depletion of B and T-cell epitopes or substitution of non-human toxins leading to a growing repertoire of human enzymes capable of inducing cell death. Similarly, the modification of classical ADCs has resulted in the first, fully recombinant versions. In this review, we discuss significant advancements in EGFR-targeting immunoconjugates, including ITs and recombinant photoactivable ADCs, which serve as a blueprint for further developments in the evolving domain of cancer immunotherapy.

Antibody-Based Immunotherapy: Alternative Approaches for the Treatment of Metastatic Melanoma

Melanoma is the least common form of skin cancer and is associated with the highest mortality. Where melanoma is mostly unresponsive to conventional therapies (e.g., chemotherapy), BRAF inhibitor treatment has shown improved therapeutic outcomes. Photodynamic therapy (PDT) relies on a light-activated compound to produce death-inducing amounts of reactive oxygen species (ROS). Their capacity to selectively accumulate in tumor cells has been confirmed in melanoma treatment with some encouraging results. However, this treatment approach has not reached clinical fruition for melanoma due to major limitations associated with the development of resistance and subsequent side effects. These adverse effects might be bypassed by immunotherapy in the form of antibody–drug conjugates (ADCs) relying on the ability of monoclonal antibodies (mAbs) to target specific tumor-associated antigens (TAAs) and to be used as carriers to specifically deliver cytotoxic warheads into corresponding tumor cells. Of late, the continued refinement of ADC therapeutic efficacy has given rise to photoimmunotherapy (PIT) (a light-sensitive compound conjugated to mAbs), which by virtue of requiring light activation only exerts its toxic effect on light-irradiated cells. As such, this review aims to highlight the potential clinical benefits of various armed antibody-based immunotherapies, including PDT, as alternative approaches for the treatment of metastatic melanoma.

Immunoinformatics design of multiepitopes peptide-based universal cancer vaccine using matrix metalloproteinase-9 protein as a target

A new approach toward cancer therapy is the use of cancer vaccine, yet the different molecular bases of cancers, reduce the effectiveness of this approach. In this article, we aim to use matrix metalloproteinase-9 protein (MMP9) which is an essential molecule in the survival and metastasis of all types of cancers as a target for universal cancer vaccine design. The reference sequence of MMP9 protein was obtained from NCBI databases. Furthermore, the B-cell and T cell-related peptides were analyzed using the IEDB website and other related soft wares. The best candidate peptides were then visualized using chimera software. Three peptides were found to be good candidates for interactions with B cells (SLPE, RLYT, and PALPR), while 10 peptides were found as good targets for interactions with MHC1 and another 10 peptides founded suitable for interactions with MHC2 with population coverages of 94.77 and 90.67%, respectively. Finally, the immune response simulation and molecular docking were done using the C-IMMSIM simulator and AutoDock Vina to confirm the effectiveness of the proposed vaccine. By the end of this project: twenty-three peptide-based vaccine was designed for use as a universal cancer vaccine which has a high world population coverage for MHC1 (94.77%) and MHC2 (90.67%) related alleles.

Nanoparticle-Delivered HIV Peptides to Dendritic Cells a Promising Approach to Generate a Therapeutic Vaccine

Finding a functional cure for HIV-1 infection will markedly decrease the social and economic burden of this disease. In this work, we have taken advantage of the antigen presenting cell role of human dendritic cells (DCs) to try to induce an immune response to HIV-derived peptide delivered to DCs using two different polycationic nanoparticles: a G4 PAMAM dendrimer modified to a 70/30 ratio of hydroxyl groups/amines and a cyclodextrin derivative. We have studied peptide delivery using a fluorescence peptide and have studied the immune response generation by cytokine determination and flow cytometry. We have found a robust delivery of the antigenic peptide to DCs and activated dendritic cell-mediated peripheral blood mononuclear cells (PBMCs) proliferation using the mixed lymphocyte reaction. However, no expression of markers indicating activation of either B or T lymphocytes was observed. Moreover, the release of the pro-inflammatory cytokine TNF-α or IL-2 was only observed when DCs treated with either the dendrimer or the dendriplex containing the peptide. Antigenic peptide delivery to DCs is a promising approach to generate a vaccine against HIV-1 infection. However, more studies, including the simultaneous delivery of several antigenic peptides from different viral proteins, can markedly improve the immune response.

Breakthrough concepts in immune-oncology: Cancer vaccines at the bedside

Clinical approval of the immune checkpoint blockade (ICB) agents for multiple cancer types has reinvigorated the long-standing work on cancer vaccines. In the pre-ICB era, clinical efforts focused on the Ag, the adjuvants, the formulation, and the mode of delivery. These translational efforts on therapeutic vaccines range from cell-based (e.g., dendritic cells vaccine Sipuleucel-T) to DNA/RNA-based platforms with various formulations (liposome), vectors (Listeria monocytogenes), or modes of delivery (intratumoral, gene gun, etc.). Despite promising preclinical results, cancer vaccine trials without ICB have historically shown little clinical activity. With the anticipation and expansion of combinatorial immunotherapeutic trials with ICB, the cancer vaccine field has entered the personalized medicine arena with recent advances in immunogenic neoantigen-based vaccines. In this article, we review the literature to organize the different cancer vaccines in the clinical space, and we will discuss their advantages, limits, and recent progress to overcome their challenges. Furthermore, we will also discuss recent preclinical advances and clinical strategies to combine vaccines with checkpoint blockade to improve therapeutic outcome and present a translational perspective on future directions.

Tumor-derived exosomes: the next generation of promising cell-free vaccines in cancer immunotherapy

Identification of immunogenic tumor antigens that are efficiently processed and delivered by dendritic cells to prime the immune system and to induce an appropriate immune response is a research hotspot in the field of cancer vaccine development. High biosafety is an additional demand. Tumor-derived exosomes (TEXs) are nanosized lipid bilayer encapsulated vesicles that shuttle bioactive information to the tumor microenvironment facilitating tumor progression. However, accumulating evidence points toward the capacity of TEXs to efficiently stimulate immune responses against tumors provided they are appropriately administered. After briefly describing the function of exosomes in cancer biology and their communication with immune cells, we summarize in this review in vitro and preclinical studies eliciting the potency of TEXs in inducing effective anti-tumor responses and recently modified strategies further improving TEX-vaccination efficacy. We interpret the available data as TEXs becoming a lead in cancer vaccination based on tumor antigen-selective high immunogenicity.

Tumor growth inhibition by mSTEAP peptide nanovaccine inducing augmented CD8+ T cell immune responses

Poly(lactic-co-glycolic) acid (PLGA) has been successfully used in drug delivery and biomaterial applications, but very little attention has been directed towards the potential in vivo effects of peptide-loaded PLGA nanoparticles (NPs), specifically the potency of intravenous (IV) STEAP peptide-loaded PLGA-NP (nanovaccine) dosing and whether STEAP-specific CD8⁺ T cells directly play a key role in tumor inhibition. To address these concerns, syngeneic prostate cancer mouse models were established and treated with either mSTEAP peptide emulsified in incomplete Freund's adjuvant (IFA) via subcutaneous (SC) injection or mSTEAP peptide nanovaccine containing the same amount of peptide via IV or SC injection. Meanwhile, mice were treated with either CD8b mAb followed by nanovaccine treatment, free mSTEAP peptide, or empty PLGA-NPs. Immune responses in these mice were examined using cytotoxicity assays at 14 days after treatment. Tumor size and survival in various treatment groups were measured and monitored. The results demonstrated that mSTEAP peptide nanovaccine resulted in tumor inhibition by eliciting a significantly stronger CD8⁺ T cell immune response when compared with the controls. Moreover, the survival periods of mice treated with mSTEAP nanovaccine were significantly longer than those of mice treated with mSTEAP peptide emulsified in IFA or the treatment controls. Additionally, it was observed that the peptide nanovaccine was mainly distributed in the mouse liver and lungs after IV injection. These findings suggest that the peptide nanovaccine is a promising immunotherapeutic approach and offers a new opportunity for prostate cancer therapies.

Nanomedicine for improvement of dendritic cell-based cancer immunotherapy

Dendritic cell (DC)-based cancer immunotherapy has shown impressive outcomes, including the development of the first FDA-approved anti-cancer vaccine. However, the clinical application of DC-based cancer immunotherapy is associated with various challenges. Promising novel tools for the administration of cancer vaccines has emerged from recent developments in nanoscale biomaterials. One current strategy to enhance targeted drug delivery, while minimizing drug-related toxicities, is the use of nanoparticles (NPs). These can be utilized for antigen delivery into DCs, which have been shown to provide potent T cell-stimulating effects. Therefore, NP delivery represents one promising approach for creating an effective and stable immune response without toxic side effects. The current review surveys cancer immunotherapy with particular attention toward NP-based delivery methods that target DCs.

Research progress and clinical prospect of immunocytotherapy for the treatment of hepatocellular carcinoma

As a common malignant tumor, hepatocellular carcinoma (HCC) has high fatality rate due to its strong metastasis and high degree of malignancy. Current treatment strategies adopted in clinical practice were still conventional surgery, assisted with interventional therapy, radiotherapy and chemotherapy. However these treatments have limited effects with high recurrence rate. Current research progress of immunocytotherapy has shown that tumor cells can be directly identified and killed by stimulating the immune function and enhancing the anti-tumor immunity in tumor microenvironment. Targeted immunotherapeutics have therefore become the hope of conquering cancer in the future. It can kill tumor cells without damaging the body's immune system and function, restore and strengthen the body's natural anti-tumor immune system. It can reduce the toxic side effects of radiotherapy and chemotherapy, reduce the recurrence rate and prolong the survival period of patients with HCC. Currently, the immune cells widely studied are mainly as follows: Dendritic cells (DC), Cytokine-induced killer (CIK), DC-CIK, Chimeric antigen receptor T cells (CAR-T), Tumor infiltrating lymphocyte (TIL) and Natural killer cell (NK). Immunocytotherapy is a long-term treatment method, some studies have combined traditional therapy with immunocytotherapy and achieved significant effects, providing experimental basis for the application of immunocytotherapy. However, there are still some difficulties in the clinical application of immune cells. In this article, we discuss the application of immunocytotherapy in the clinical treatment of HCC, their effectiveness either alone or in combination with conventional therapies, and how future immunocytotherapeutics can be further improved from investigations in tumour immunology.

Factor VIII Fc Fusion Protein but not FVIII Drives Human Monocyte-Derived Dendritic Cell Activation via FcγRIIa

This study compares the effect of recombinant Factor VIII Fc fusion protein (rFVIII-Fc) with recombinant FVIII (rFVIII) on monocyte-derived dendritic cells (moDC's). Cells treated with rFVIII-Fc showed morphological changes typical for cell activation, had a significant up-regulation of cell activation markers and produced higher levels of pro-inflammatory cytokines. Even after stimulation with Lipopolysaccharides, the addition of rFVIII-Fc led to increased expression of activation markers, indicating that rFVIII-Fc is capable of amplifying the maturation signal. On the contrary, cultivation of moDC's with rFVIII did not alter cell morphology or increase surface activation marker expression and pro-inflammatory cytokine production. The binding of the Fc domain to the activating Fcγ receptor IIa (FcγRIIa) can cause cell activation. Therefore, the effect of rFVIII-Fc on FcγRIIa was analyzed in detail. Cultivation of moDC's with rFVIII-Fc led to increased phosphorylation of FcγRIIa, which was not detected for rFVIII. Blocking FcγRIIa prior to the cultivation with rFVIII-Fc significantly reduced the activating effect of rFVIII-Fc, indicating that rFVIII-Fc-induced moDC activation was caused by FcγRIIa. Moreover, rFVIII-Fc bound to FCGR2A-transfected human embryonic kidney 293 cells. Taken together, our data present a new mechanism of moDC activation by rFVIII-Fc via FcγRIIa.

Photodynamic Modulation of Type 1 Interferon Pathway on Melanoma Cells Promotes Dendritic Cell Activation

The immune response against cancer generated by type-I-interferons (IFN-1) has recently been described. Exogenous and endogenous IFN-α/β have an important role in immune surveillance and control of tumor development. In addition, IFN-1s have recently emerged as novel DAMPs for the consecutive events connecting innate and adaptive immunity, and they also have been postulated as an essential requirement for induction of immunogenic cell death (ICD). In this context, photodynamic therapy (PDT) has been previously linked to the ICD. PDT consists in the administration of a photosensitizer (PS) and its activation by irradiation of the affected area with visible light producing excitation of the PS. This leads to the local generation of harmful reactive oxygen species (ROS) with limited or no systemic defects. In the current work, Me-ALA inducing PpIX (endogenous PS) was administrated to B16-OVA melanoma cells. PpIX preferentially localized in the endoplasmic reticulum (ER). Subsequent PpIX activation with visible light significantly induced oxidative ER-stress mediated-apoptotic cell death. Under these conditions, the present study was the first to report the in vitro upregulation of IFN-1 expression in response to photodynamic treatment in melanoma. This IFN-α/β transcripts upregulation was concurrent with IRF-3 phosphorylation at levels that efficiently activated STAT1 and increased ligand receptor (cGAS) and ISG (CXCL10, MX1, ISG15) expression. The IFN-1 pathway has been identified as a critical molecular pathway for the antitumor host immune response, more specifically for the dendritic cells (DCs) functions. In this sense, PDT-treated melanoma cells induced IFN-1-dependent phenotypic maturation of monocyte-derived dendritic cells (DCs) by enhancing co-stimulatory signals (CD80, MHC-II) and tumor-directed chemotaxis. Collectively, our findings showed a new effect of PDT-treated cancer cells by modulating the IFN-1 pathway and its impact on the activation of DCs, emphasizing the potential relevance of PDT in adoptive immunotherapy protocols.

Current Approaches and Challenges in the Molecular Therapeutic Targeting of Glioblastoma

Surgical resection continues to predominate as the primary treatment modality in glioblastoma (GBM). Effective chemotherapeutic/biologic agents capable of targeting GBM have yet to be developed in part because of the exceptionally heterogeneous nature and unique microenvironmental conditions associated with this malignant neoplasm. Temozolomide and bevacizumab represent the only U.S. Food and Drug Administration-approved agents for primary and recurrent GBM, respectively. Given the high therapeutic resistance of GBM to current therapies, as well as the failure of bevacizumab to prolong overall survival, new therapeutic agents are urgently warranted and are now in the preclinical and clinical phases of development. Accordingly, clinical trials evaluating the efficacy of immune checkpoint inhibition, chimeric antigen receptor T cell therapy, virotherapies, and tumor vaccination therapy are all under way in GBM. Herein, we review the application of current/novel therapeutics in GBM and in so doing attempt to highlight the most promising solutions to overcome current failures.

Unleashing Tumour-Dendritic Cells to Fight Cancer by Tackling Their Three A's: Abundance, Activation and Antigen-Delivery

Recent advances in cancer immunotherapy have mainly focused on re-activating T-cell responses against cancer cells. However, both priming and activation of effector T-cell responses against cancer-specific antigens require cross-talk with dendritic cells (DCs), which are responsible for the capturing, processing and presentation of tumour-(neo)antigens to T cells. DCs consequently constitute an essential target in efforts to generate therapeutic immunity against cancer. This review will discuss recent research that is unlocking the cancer-fighting potential of tumour-infiltrating DCs. First, the complexity of DCs in the tumour microenvironment regarding the different subsets and the difficulty of translating mouse data into equivalent human data will be briefly touched upon. Mainly, possible solutions to problems currently faced in DC-based cancer treatments will be discussed, including their infiltration into tumours, activation strategies, and antigen delivery methods. In this way, we hope to put together a broad picture of potential synergistic therapies that could be implemented to harness the full capacity of tumour-infiltrating DCs to stimulate anti-tumour immune responses in patients.

Enhancing Dendritic Cell Therapy in Solid Tumors with Immunomodulating Conventional Treatment

Dendritic cells (DCs) are the most potent antigen-presenting cells and are the key initiator of tumor-specific immune responses. These characteristics are exploited by DC therapy, where DCs are ex vivo loaded with tumor-associated antigens (TAAs) and used to induce tumor-specific immune responses. Unfortunately, clinical responses remain limited to a proportion of the patients. Tumor characteristics and the immunosuppressive tumor microenvironment (TME) of the tumor are likely hampering efficacy of DC therapy. Therefore, reducing the immunosuppressive TME by combining DC therapy with other treatments could be a promising strategy. Initially, conventional cancer therapies, such as chemotherapy and radiotherapy, were thought to specifically target cancerous cells. Recent insights indicate that these therapies additionally augment tumor immunity by targeting immunosuppressive cell subsets in the TME, inducing immunogenic cell death (ICD), or blocking inhibitory molecules. Therefore, combining DC therapy with registered therapies such as chemotherapy, radiotherapy, or checkpoint inhibitors could be a promising treatment strategy to improve the efficacy of DC therapy. In this review, we evaluate various clinical applicable combination strategies to improve the efficacy of DC therapy.

IL-15 and a Two-Step Maturation Process Improve Bone Marrow-Derived Dendritic Cell Cancer Vaccine

In the last 20 years, dendritic cells (DCs) have been largely used as a platform for therapeutic vaccination in cancer patients. However, despite its proven safety and ability to induce cancer specific immune responses, the clinical benefits of DC-based immunotherapy are currently very limited. Thus, novel approaches are still needed to boost its efficacy. Our group recently showed that squaric acid treatment of antigens is an important adjuvant that can increase vaccine-induced downstream immune responses and therapeutic outcomes. Here we further improved this dendritic cell vaccine formulation by developing a new method for differentiating and maturing DCs from their bone marrow precursors. Our data demonstrate that bone marrow-derived DCs differentiated with GM-CSF and IL-15 and matured with a maturation cocktail in two steps present a more mature and immunogenic phenotype, compared to standard DC preparations. Further suppression of the prostaglandin E₂ pathway achieved even more immunogenic DC phenotypes. This vaccine was more potent at delaying tumor growth, improved animal survival and induced a more immunogenic and Th1-skewed T cell response in an ovarian cancer mouse model. These promising results support future efforts for the clinical translation of this approach.

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.

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.

Diamonds in the Rough: Harnessing Tumor-Associated Myeloid Cells for Cancer Therapy

Therapeutic approaches that engage immune cells to treat cancer are becoming increasingly utilized in the clinics and demonstrated durable clinical benefit in several solid tumor types. Most of the current immunotherapies focus on manipulating T cells, however, the tumor microenvironment (TME) is abundantly infiltrated by a heterogeneous population of tumor-associated myeloid cells, including tumor-associated macrophages (TAMs), tumor-associated dendritic cells (TADCs), tumor-associated neutrophils (TANs), and myeloid-derived suppressor cells (MDSCs). Educated by signals perceived in the TME, these cells often acquire tumor-promoting properties ultimately favoring disease progression. Upon appropriate stimuli, myeloid cells can exhibit cytoxic, phagocytic, and antigen-presenting activities thereby bolstering antitumor immune responses. Thus, depletion, reprogramming or reactivation of myeloid cells to either directly eradicate malignant cells or promote antitumor T-cell responses is an emerging field of interest. In this review, we briefly discuss the tumor-promoting and tumor-suppressive roles of myeloid cells in the TME, and describe potential therapeutic strategies in preclinical and clinical development that aim to target them to further expand the range of current treatment options.

Cell death and immunity in cancer: From danger signals to mimicry of pathogen defense responses

The immunogenicity of cancer cells is an emerging determinant of anti-cancer immunotherapy. Beyond developing immunostimulatory regimens like dendritic cell-based vaccines, immune-checkpoint blockers, and adoptive T-cell transfer, investigators are beginning to focus on the immunobiology of dying cancer cells and its relevance for the success of anticancer immunotherapies. It is currently accepted that cancer cells may die in response to anti-cancer therapies through regulated cell death programs, which may either repress or increase their immunogenic potential. In particular, the induction of immunogenic cancer cell death (ICD), which is hallmarked by the emission of damage-associated molecular patterns (DAMPs); molecules analogous to pathogen-associated molecular patterns (PAMPs) acting as danger signals/alarmins, is of great relevance in cancer therapy. These ICD-associated danger signals favor immunomodulatory responses that lead to tumor-associated antigens (TAAs)-directed T-cell immunity, which paves way for the removal of residual, treatment-resistant cancer cells. It is also emerging that cancer cells succumbing to ICD can orchestrate "altered-self mimicry" i.e. mimicry of pathogen defense responses, on the levels of nucleic acids and/or chemokines (resulting in type I interferon/IFN responses or pathogen response-like neutrophil activity). In this review, we exhaustively describe the main molecular, immunological, preclinical, and clinical aspects of immunosuppressive cell death or ICD (with respect to apoptosis, necrosis and necroptosis). We also provide an extensive historical background of these fields, with special attention to the self/non-self and danger models, which have shaped the field of cell death immunology.

Bags versus flasks: a comparison of cell culture systems for the production of dendritic cell-based immunotherapies

In recent years, cell-based therapies targeting the immune system have emerged as promising strategies for cancer treatment. This review summarizes manufacturing challenges related to production of antigen presenting cells as a patient-tailored cancer therapy. Understanding cell-material interactions is essential because in vitro cell culture manipulations to obtain mature antigen-producing cells can significantly alter their in vivo performance. Traditional antigen-producing cell culture protocols often rely on cell adhesion to surface-treated hydrophilic polystyrene flasks. More recent commercial and investigational cancer immunotherapy products were manufactured using suspension cell culture in closed hydrophobic fluoropolymer bags. The shift to closed cell culture systems can decrease risks of contamination by individual operators, as well as facilitate scale-up and automation. Selecting closed cell culture bags over traditional open culture systems entails different handling procedures and processing controls, which can affect product quality. Changes in culture vessels also entail changes in vessel materials and geometry, which may alter the cell microenvironment and resulting cell fate decisions. Strategically designed culture systems will pave the way for the generation of more sophisticated and highly potent cell-based cancer vaccines. As an increasing number of cell-based therapies enter the clinic, the selection of appropriate cell culture vessels and materials becomes a critical consideration that can impact the therapeutic efficacy of the product, and hence clinical outcomes and patient quality of life.

The enhanced antitumor-specific immune response with mannose- and CpG-ODN-coated liposomes delivering TRP2 peptide

PURPOSE

Dendritic cell (DC)-based cancer vaccines is a newly emerging and potent form of immune therapy. As for any new technology, there are still considerable challenges that need to be addressed. Here, we investigate the antitumor potential of a novel liposomal vaccine, M/CpG-ODN-TRP2-Lipo.

METHODS

We developed a vaccination strategy by assembling the DC-targeting mannose and immune adjuvant CpG-ODN on the surface of liposomes, which were loaded with melanoma-specific TRP2_180-188 peptide as liposomal vaccine. M/CpG-ODN-TRP2-Lipo treatment was used to intendedly induce activation of DCs and antitumor- specific immune response in vivo.

RESULTS

Our results demonstrated in vitro that the prepared liposomal particles were efficiently taken up by DCs. This uptake led to an enhanced activation of DCs, as measured by the upregulation of MHC II, CD80, and CD86. Furthermore, M/CpG-ODN-TRP2-Lipo effectively inhibited the growth of implanted B16 melanoma and prolonged the survival of mice. This therapy significantly reduced the number of myeloid-derived suppressor cells (MDSCs) and regulatory T cells, while simultaneously increasing the number of activated T cells, tumor antigen-specific CD8⁺ cytotoxic T cells, and interferon-γ-producing cells. At the same time, it was found to suppress tumor angiogenesis and tumor cell proliferation, as well as up-regulate their apoptosis. Interestingly, MyD88-knockout mice had significantly shorter median survival times compared to wild-type mice following the administration of M/CpG-ODN-TRP2-Lipo.

CONCLUSIONS

The results suggested that the antitumor activities of the vaccine partially rely on the Myd88 signaling pathway. Interestingly, compared to whole tumor cell lysate-based vaccine, M/CpG-ODN-TRP2-Lipo, tumor specific antigen peptide-based vaccine, improved survival of tumor-bearing mice as well as enhanced their antitumor responses. All in all, we describe a novel vaccine formulation, M/CpG-ODN-TRP2-Lipo, with the aim of improving antitumor responses by alleviating the immunosuppressive environment in tumors.

SYK-targeted dendritic cell-mediated cytotoxic T lymphocytes enhance the effect of immunotherapy on retinoblastoma

PURPOSE

Retinoblastoma (RB) is the most common primary intraocular tumor in children. Chemotherapy is currently the main method of RB treatment. Unfortunately, RB often becomes chemoresistant and turns lethal. Here, we used in vitro cell immunotherapy to explore whether adoptive immunotherapy could be used as a potential treatment for RB. We focused on spleen tyrosine kinase (SYK), which is significantly upregulated in RB cells and serves as a marker for RB cells.

METHODS

Using lentiviruses, we genetically modified dendritic cells (DCs) to express and present the SYK peptide antigen to cytotoxic T lymphocytes (CTLs) in vitro. We used SYK-negative cell lines (MDA-MB-231, MCF-10A, and hTERT-RPE1) and SYK-positive cell lines (MCF-7 and RB-Y79) to evaluate the specificity and cytotoxicity of DC presented CTLs using FACS, live-cell imaging, and RNA interference.

RESULTS

The cytotoxicity of CTLs induced by SYK-overexpressing DCs (SYK-DC-CTLs) was enhanced more than three times in SYK-positive cell lines compared with SYK-negative cell lines. DCs primed with SYK could drive CTL cytotoxicity against SYK-positive cell lines but not against SYK-negative cell lines. Moreover, SYK-silenced RB-Y79 cells successfully evaded the cytotoxic attack from SYK-DC-CTLs. However, SYK-DC-CTLs could target SYK overexpressed hTERT-RPE1 cells, suggesting that SYK is a specific antigen for RB. Furthermore, SYK-DC-CTL exhibited specific cytotoxicity against carboplatin-resistant RB-Y79 cells in vitro.

CONCLUSIONS

Our data showed that SYK could be a potential immunotherapy target mediated by DCs. We propose SYK as a candidate target for treatment of chemoresistant RB.

Immunotherapy of patient with hepatocellular carcinoma using cytotoxic T lymphocytes ex vivo activated with tumor antigen-pulsed dendritic cells

Purpose The aim of this study was to evaluate the clinical response of immunotherapy with dendritic cell-cytotoxic T lymphocytes (DC-CTLs) in patients with hepatocellular carcinoma (HCC).

Method Sixty-eight patients with a confirmed diagnosis of HCC and who received follow-up until December 2015 were enrolled. We measured immune phenotypes of DCs and activated T cells using flow cytometry and clinical indexes using an electrochemiluminescence method.

Results DCs exhibited up-regulation of the maturation markers CD83, CD80, CD11c, and CD86 on day8. Levels of IFN-γ and TNF-α were higher in the DCs pulsed with tumor-associated antigens (TAAs) than in DCs with a non-proliferative recombinant adenovirus. The percentage of regulatory T cells (Tregs) decreased in patients after DC-CTLs therapy. In addition, serum levels of AFP, AFP-L3, ALT, and CA19-9 were significantly reduced in these patients. Quality of life was improved, especially on physical functioning scales. Median overall survival (OS) and progression-free survival (PFS) were 8.2 months and 4.3 months, respectively, for the control group and 12.8 months and 9 months, respectively, for the DC-CTL group. Patients treated with DC-CTLs therapy showed a statistically significant PFS and OS curve (OS: p=0.016; PFS: p<0.0001). In addition, no serious adverse reactions were observed.

Conclusion This study indicated that Tregs, as well as serum levels of AFP, AFP-L3, ALT, and CA19-9, which were correlated with a poor prognosis, decreased after DC-CTL treatments. The OS, PFS and the quality of life of HCC patients partially improved.

Caveolin-1 Expression Increases upon Maturation in Dendritic Cells and Promotes Their Migration to Lymph Nodes Thereby Favoring the Induction of CD8+ T Cell Responses

Dendritic cell (DC) trafficking from peripheral tissues to lymph nodes (LNs) is a key step required to initiate T cell responses against pathogens as well as tumors. In this context, cellular membrane protrusions and the actin cytoskeleton are essential to guide DC migration towards chemotactic signals. Caveolin-1 (CAV1) is a scaffolding protein that modulates signaling pathways leading to remodeling of the actin cytoskeleton and enhanced migration of cancer cells. However, whether CAV1 is relevant for DC function and specifically for DC migration to LNs is unknown. Here, we show that CAV1 expression is upregulated in DCs upon LPS- and TNF-α-induced maturation. CAV1 deficiency did not affect differentiation, maturation, or the ability of DCs to activate CD8⁺ T cells in vitro. However, CAV1-deficient (CAV1^-/-) DCs displayed reduced in vivo trafficking to draining LNs in control and inflammatory conditions. In vitro, CAV1^-/- DCs showed reduced directional migration in CCL21 gradients in transwell assays without affecting migration velocity in confined microchannels or three-dimensional collagen matrices. In addition, CAV1^-/- DCs displayed reduced activation of the small GTPase Rac1, a regulator of actin cytoskeletal remodeling, and lower numbers of F-actin-forming protrusions. Furthermore, mice adoptively transferred with peptide-pulsed CAV1^-/- DCs showed reduced CD8⁺ T cell responses and antitumor protection. Our results suggest that CAV1 promotes the activation of Rac1 and the formation of membrane protrusions that favor DC chemotactic trafficking toward LNs where they can initiate cytotoxic T cell responses.

Beyond the vicious cycle: The role of innate osteoimmunity, automimicry and tumor-inherent changes in dictating bone metastasis

Bone metastasis is a fatal consequence of a subset of solid malignancies that fail to respond to conventional therapies. While a myriad of factors contribute to osteotropism and disseminated cell survival and outgrowth in bone, efforts to inhibit tumor cell growth in the bone-metastatic niche have largely relied on measures that disrupt the bi-directional interactions between bone resident and tumor cells. However, the targeting of isolated stromal interactions has proven ineffective to date in inhibiting bone-metastatic progression and patient mortality. Osteoimmune regulation is now emerging as a critical determinant of metastatic growth in the bone microenvironment. While this has highlighted the importance of innate immune populations in dictating the temporal development of overt bone metastases, the osteoimmunological processes that underpin tumor cell progression in bone remain severely underexplored. Along with tumor-intrinsic alterations that occur specifically within the bone microenvironment, innate osteoimmunological crosstalk poses an exciting area of future discovery and therapeutic development. Here we review current knowledge of the unique exchange that occurs between bone resident cells, innate immune populations and tumor cells that leads to the establishment of a tumor-permissive milieu.