Endogenous/Exogenous Nanovaccines Synergistically Enhance Dendritic Cell-Mediated Tumor Immunotherapy

Present and future of cancer nano-immunotherapy: opportunities, obstacles and challenges

Clinically, multimodal therapies are adopted worldwide for the management of cancer, which continues to be a leading cause of death. In recent years, immunotherapy has firmly established itself as a new paradigm in cancer care that activates the body's immune defense to cope with cancer. Immunotherapy has resulted in significant breakthroughs in the treatment of stubborn tumors, dramatically improving the clinical outcome of cancer patients. Multiple forms of cancer immunotherapy, including immune checkpoint inhibitors (ICIs), adoptive cell therapy and cancer vaccines, have become widely available. However, the effectiveness of these immunotherapies is not much satisfying. Many cancer patients do not respond to immunotherapy, and disease recurrence appears to be unavoidable because of the rapidly evolving resistance. Moreover, immunotherapies can give rise to severe off-target immune-related adverse events. Strategies to remove these hindrances mainly focus on the development of combinatorial therapies or the exploitation of novel immunotherapeutic mediations. Nanomaterials carrying anticancer agents to the target site are considered as practical approaches for cancer treatment. Nanomedicine combined with immunotherapies offers the possibility to potentiate systemic antitumor immunity and to facilitate selective cytotoxicity against cancer cells in an effective and safe manner. A myriad of nano-enabled cancer immunotherapies are currently under clinical investigation. Owing to gaps between preclinical and clinical studies, nano-immunotherapy faces multiple challenges, including the biosafety of nanomaterials and clinical trial design. In this review, we provide an overview of cancer immunotherapy and summarize the evidence indicating how nanomedicine-based approaches increase the efficacy of immunotherapies. We also discuss the key challenges that have emerged in the era of nanotechnology-based cancer immunotherapy. Taken together, combination nano-immunotherapy is drawing increasing attention, and it is anticipated that the combined treatment will achieve the desired success in clinical cancer therapy.

Engineered Carrier-Free Nanosystem-Induced In Situ Therapeutic Vaccines for Potent Cancer Immunotherapy

In situ vaccines that can stimulate tumor immune response have emerged as a breakthrough in antitumor therapy. However, the immunosuppressed tumor microenvironment and insufficient infiltration of immune cells lead to ineffective antitumor immunity. Hence, a biomimetic carrier-free nanosystem (BCC) to induce synergistic phototherapy/chemotherapy-driven in situ vaccines was designed. A carrier-free nanosystem was developed using phototherapeutic reagents CyI and celastrol as raw materials. In vitro and in vivo studies have shown that under NIR light irradiation, BCC-mediated photo/chemotherapy not only accelerates the release of drugs to deeper parts of tumors, achieving timing and light-controlled drug delivery to result in cell apoptosis, but also effectively stimulates the antitumor response to induce in situ vaccine, which could invoke long-lasting antitumor immunity to inhibit tumor metastasis and eliminate distant tumor. This therapeutic strategy holds promise for priming robust innate and adaptive immune responses, arresting cancer progression, and inducing tumor dormancy.

Pickering emulsion-guided monomeric delivery of monophosphoryl lipid A for enhanced vaccination

Immunological adjuvants are vaccine components that enhance long-lasting adaptive immune responses to weakly immunogenic antigens. Monophosphoryl lipid A (MPLA) is a potent and safe vaccine adjuvant that initiates an early innate immune response by binding to the Toll-like receptor 4 (TLR4). Importantly, the binding and recognition process is highly dependent on the monomeric state of MPLA. However, current vaccine delivery systems often prioritize improving the loading efficiency of MPLA, while neglecting the need to maintain its monomeric form for optimal immune activation. Here, we introduce a Pickering emulsion-guided MPLA monomeric delivery system (PMMS), which embed MPLA into the oil-water interface to achieve the monomeric loading of MPLA. During interactions with antigen-presenting cells, PMMS functions as a chaperone for MPLA, facilitating efficient recognition by TLR4 regardless of the presence of lipopolysaccharide-binding proteins. At the injection site, PMMS efficiently elicited local immune responses, subsequently promoting the migration of antigen-internalized dendritic cells to the lymph nodes. Within the draining lymph nodes, PMMS enhanced antigen presentation and maturation of dendritic cells. In C57BL/6 mice models, PMMS vaccination provoked potent antigen-specific CD8+ T cell-based immune responses. Additionally, PMMS demonstrated strong anti-tumor effects against E.G7-OVA lymphoma. These data indicate that PMMS provides a straightforward and efficient strategy for delivering monomeric MPLA to achieve robust cellular immune responses and effective cancer immunotherapy.

A photo-responsive self-healing hydrogel loaded with immunoadjuvants and MoS2 nanosheets for combating post-resection breast cancer recurrence

Tumor recurrence after surgical resection remains a significant challenge in breast cancer treatment. Immune checkpoint blockade therapy, as a promising alternative therapy, faces limitations in combating tumor recurrence due to the low immune response rate. In this study, we developed an implantable photo-responsive self-healing hydrogel loaded with MoS2 nanosheets and the immunoadjuvant R837 (PVA-MoS2-R837, PMR hydrogel) for in situ generation of tumor-associated antigens at the post-surgical site of the primary tumor, enabling sustained and effective activation of the immune response. This PMR hydrogel exhibited potential for near-infrared (NIR) light response, tissue adhesion, self-healing, and sustained adjuvant release. When implanted at the site after tumor resection, NIR irradiation triggered a photothermal effect, resulting in the ablation of residual cancer cells. The in situ-generated tumor-associated antigens promoted dendritic cell (DC) maturation. In a mouse model, PMR hydrogel-mediated photothermal therapy combined with immune checkpoint blockade effectively inhibited the recurrence of resected tumors, providing new insights for combating post-resection breast cancer recurrence.

Liposomal Delivery of an Immunostimulatory CpG Induces Robust Antitumor Immunity and Long-Term Immune Memory by Reprogramming Tumor-Associated Macrophages

Tumor-associated macrophages (TAMs)-representative immune-suppressive cells in the tumor microenvironment (TME)-are known to promote tumor progression and metastasis, and thus are considered an attractive target for cancer therapy. However, current TAM-targeting strategies are insufficient to result in robust antitumor efficacy. Here, a small lipid nanoparticle encapsulating immunostimulatory CpG oligodeoxynucleotides (SLNP@CpG) is reported as a new immunotherapeutic modality that can reprogram TAMs and further bridge innate-to-adaptive immunity. It is found that SLNP@CpG treatment enhances macrophage-mediated phagocytosis of cancer cells and tumor antigen cross-presentation, and skews the polarization state of macrophages in vitro. Intratumoral injection of SLNP@CpG into an established murine E.G7-OVA tumor model significantly suppresses tumor growth and considerably prolongs survival, completely eradicating tumors in 83.3% of mice. Furthermore, tumor-free mice resist rechallenge with E.G7-OVA cancer cells through induction of immunological memory and long-term antitumor immunity. SLNP@CpG even exerts antitumor efficacy in an aggressive B16-F10 melanoma model by remodeling TME toward immune stimulation and tumor elimination. These findings suggest that, by modulating the function of TAMs and reshaping an immunosuppressive TME, the SLNP@CpG nanomedicine developed here may become a promising immunotherapeutic option applicable to a variety of tumors.

The role of dendritic cells in cancer immunity and therapeutic strategies

Dendritic cells (DCs) are asserted as the most potent antigen-presenting cells (APCs) that orchestrate both innate and adaptive immunity, being extremely effective in the induction of robust anti-cancer T cell responses. Hence, the modulation of DCs function represents an attractive target for improving cancer immunotherapy efficacy. A better understanding of the immunobiology of DCs, the interaction among DCs, immune effector cells and tumor cells in tumor microenvironment (TME) and the latest advances in biomedical engineering technology would be required for the design of optimal DC-based immunotherapy. In this review, we focus on elaborating the immunobiology of DCs in healthy and cancer environments, the recent advances in the development of enhancing endogenous DCs immunocompetence via immunomodulators as well as DC-based vaccines. The rapidly developing field of applying nanotechnology to improve DC-based immunotherapy is also highlighted.

Rab37 mediates trafficking and membrane presentation of PD-1 to sustain T cell exhaustion in lung cancer

BACKGROUND

Programmed cell death protein 1 (PD-1) is an immune checkpoint receptor expressed on the surface of T cells. High expression of PD-1 leads to T-cell dysfunction in the tumor microenvironment (TME). However, the mechanism of intracellular trafficking and plasma membrane presentation of PD-1 remains unclear.

METHODS

Multiple databases of lung cancer patients were integratively analyzed to screen Rab proteins and potential immune-related signaling pathways. Imaging and various biochemical assays were performed in Jurkat T cells, splenocytes, and human peripheral blood mononuclear cells (PBMCs). Rab37 knockout mice and specimens of lung cancer patients were used to validate the concept.

RESULTS

Here, we identify novel mechanisms of intracellular trafficking and plasma membrane presentation of PD-1 mediated by Rab37 small GTPase to sustain T cell exhaustion, thereby leading to poor patient outcome. PD-1 colocalized with Rab37-specific vesicles of T cells in a GTP-dependent manner whereby Rab37 mediated dynamic trafficking and membrane presentation of PD-1. However, glycosylation mutant PD-1 delayed cargo recruitment to the Rab37 vesicles, thus stalling membrane presentation. Notably, T cell proliferation and activity were upregulated in tumor-infiltrating T cells from the tumor-bearing Rab37 knockout mice compared to those from wild type. Clinically, the multiplex immunofluorescence-immunohistochemical assay indicated that patients with high Rab37+/PD-1+/TIM3+/CD8+ tumor infiltrating T cell profile correlated with advanced tumor stages and poor overall survival. Moreover, human PBMCs from patients demonstrated high expression of Rab37, which positively correlated with elevated levels of PD-1+ and TIM3+ in CD8+ T cells exhibiting reduced tumoricidal activity.

CONCLUSIONS

Our results provide the first evidence that Rab37 small GTPase mediates trafficking and membrane presentation of PD-1 to sustain T cell exhaustion, and the tumor promoting function of Rab37/PD-1 axis in T cells of TME in lung cancer. The expression profile of Rab37high/PD-1high/TIM3high in tumor-infiltrating CD8+ T cells is a biomarker for poor prognosis in lung cancer patients.

An Immunomodulatory Zinc-Alum/Ovalbumin Nanovaccine Boosts Cancer Metalloimmunotherapy Through Erythrocyte-Assisted Cascade Immune Activation

Cancer therapeutic vaccines are powerful tools for immune system activation and eliciting protective responses against tumors. However, their efficacy has often been hindered by weak and slow immune responses. Here, the authors introduce an immunization strategy employing senescent erythrocytes to facilitate the accumulation of immunomodulatory zinc-Alum/ovalbumin (ZAlum/OVA) nanovaccines within both the spleen and solid tumors by temporarily saturating liver macrophages. This approach sets the stage for boosted cancer metalloimmunotherapy through a cascade immune activation. The accumulation of ZAlum/OVA nanovaccines in the spleen substantially enhances autophagy-dependent antigen presentation in dendritic cells, rapidly initiating OVA-specific T-cell responses against solid tumors. Concurrently, ZAlum/OVA nanovaccines accumulated in the tumor microenvironment trigger immunogenic cell death, leading to the induction of individualized tumor-associated antigen-specific T cell responses and increased T cell infiltration. This erythrocyte-assisted cascade immune activation using ZAlum/OVA nanovaccines results in rapid and robust antitumor immunity induction, holding great potential for clinical cancer metalloimmunotherapy.

Enhancing Dendritic Cell Activation Through Manganese-Coated Nanovaccine Targeting the cGAS-STING Pathway

Background

Nanovaccines have emerged as a promising vaccination strategy, exhibiting their capacity to deliver antigens and adjuvants to elicit specific immune responses. Despite this potential, optimizing the design and delivery of nanovaccines remains a challenge.

Methods

In this study, we engineered a dendritic mesoporous silica-based nanocarrier enveloped in a metal-phenolic network (MPN) layer containing divalent manganese ions and tannic acid (MSN@MT). This nanocarrier was tailored for antigen loading to serve as a nanovaccine, aiming to activate the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway in dendritic cells (DCs). Our experimental approach encompassed both cellular assays and mouse immunizations, allowing a comprehensive evaluation of the nanovaccine's impact on DC activation and its influence on the generation of antigen-specific T-cell responses.

Results

MSN@MT demonstrated a remarkable enhancement in humoral and cellular immune responses in mice compared to control groups. This highlights the potential of MSN@MT to effectively trigger the cGAS-STING pathway in DCs, resulting in robust immune responses.

Conclusion

Our study introduces MSN@MT, a unique nanocarrier incorporating divalent manganese ions and tannic acid, showcasing its exceptional ability to amplify immune responses by activating the cGAS-STING pathway in DCs. This innovation signifies a stride in refining nanovaccine design for potent immune activation.

Nanovaccine-based strategies for lymph node targeted delivery and imaging in tumor immunotherapy

Therapeutic tumor vaccines have attracted considerable attention in the past decade; they can induce tumor regression, eradicate minimal residual disease, establish lasting immune memory and avoid non-specific and adverse side effects. However, the challenge in the field of therapeutic tumor vaccines is ensuring the delivery of immune components to the lymph nodes (LNs) to activate immune cells. The clinical response rate of traditional therapeutic tumor vaccines falls short of expectations due to inadequate lymph node delivery. With the rapid development of nanotechnology, a large number of nanoplatform-based LN-targeting nanovaccines have been exploited for optimizing tumor immunotherapies. In addition, some nanovaccines possess non-invasive visualization performance, which is benefit for understanding the kinetics of nanovaccine exposure in LNs. Herein, we present the parameters of nanoplatforms, such as size, surface modification, shape, and deformability, which affect the LN-targeting functions of nanovaccines. The recent advances in nanoplatforms with different components promoting LN-targeting are also summarized. Furthermore, emerging LNs-targeting nanoplatform-mediated imaging strategies to both improve targeting performance and enhance the quality of LN imaging are discussed. Finally, we summarize the prospects and challenges of nanoplatform-based LN-targeting and /or imaging strategies, which optimize the clinical efficacy of nanovaccines in tumor immunotherapies.

Biomaterials Facilitating Dendritic Cell-Mediated Cancer Immunotherapy

Dendritic cell (DC)-based cancer immunotherapy has exhibited remarkable clinical prospects because DCs play a central role in initiating and regulating adaptive immune responses. However, the application of traditional DC-mediated immunotherapy is limited due to insufficient antigen delivery, inadequate antigen presentation, and high levels of immunosuppression. To address these challenges, engineered biomaterials have been exploited to enhance DC-mediated immunotherapeutic effects. In this review, vital principal components that can enhance DC-mediated immunotherapeutic effects are first introduced. The parameters considered in the rational design of biomaterials, including targeting modifications, size, shape, surface, and mechanical properties, which can affect biomaterial optimization of DC functions, are further summarized. Moreover, recent applications of various engineered biomaterials in the field of DC-mediated immunotherapy are reviewed, including those serve as immune component delivery platforms, remodel the tumor microenvironment, and synergistically enhance the effects of other antitumor therapies. Overall, the present review comprehensively and systematically summarizes biomaterials related to the promotion of DC functions; and specifically focuses on the recent advances in biomaterial designs for DC activation to eradicate tumors. The challenges and opportunities of treatment strategies designed to amplify DCs via the application of biomaterials are discussed with the aim of inspiring the clinical translation of future DC-mediated cancer immunotherapies.