Lymph Node-Targeting Nanovaccine through Antigen-CpG Self-Assembly Potentiates Cytotoxic T Cell Activation

Targeting lymph nodes for enhanced cancer vaccination: From nanotechnology to tissue engineering

Lymph nodes (LNs) occupy a critical position in initiating and augmenting immune responses, both spatially and functionally. In cancer immunotherapy, tumor-specific vaccines are blooming as a powerful tool to suppress the growth of existing tumors, as well as provide preventative efficacy against tumorigenesis. Delivering these vaccines more efficiently to LNs, where antigen-presenting cells (APCs) and T cells abundantly reside, is under extensive exploration. Formulating vaccines into nanomedicines, optimizing their physiochemical properties, and surface modification to specifically bind molecules expressed on LNs or APCs, are common routes and have brought encouraging outcomes. Alternatively, porous scaffolds can be engineered to attract APCs and provide an environment for them to mature, proliferate and migrate to LNs. A relatively new research direction is inducing the formation of LN-like organoids, which have shown positive relevance to tumor prognosis. Cutting-edge advances in these directions and discussions from a future perspective are given here, from which the up-to-date pattern of cancer vaccination will be drawn to hopefully provide basic guidance to future studies.

Engineering customized nanovaccines for enhanced cancer immunotherapy

Nanovaccines have gathered significant attention for their potential to elicit tumor-specific immunological responses. Despite notable progress in tumor immunotherapy, nanovaccines still encounter considerable challenges such as low delivery efficiency, limited targeting ability, and suboptimal efficacy. With an aim of addressing these issues, engineering customized nanovaccines through modification or functionalization has emerged as a promising approach. These tailored nanovaccines not only enhance antigen presentation, but also effectively modulate immunosuppression within the tumor microenvironment. Specifically, they are distinguished by their diverse sizes, shapes, charges, structures, and unique physicochemical properties, along with targeting ligands. These features of nanovaccines facilitate lymph node accumulation and activation/regulation of immune cells. This overview of bespoke nanovaccines underscores their potential in both prophylactic and therapeutic applications, offering insights into their future development and role in cancer immunotherapy.

Let-7i enhances anti-tumour immunity and suppresses ovarian tumour growth

Cancer immunotherapy has seen significant success in the last decade for cancer management by enhancing endogenous cancer immunity. However, immunotherapies developed thus far have seen limited success in the majority of high-grade serous carcinoma (HGSC) ovarian cancer patients. This is largely due to the highly immunosuppressive tumour microenvironment of HGSC and late-stage identification. Thus, novel treatment interventions are needed to overcome this immunosuppression and complement existing immunotherapies. Here, we have identified through analysis of > 600 human HGSC tumours a critical role for Let-7i in modulating the tumoural immune network. Tumoural expression of Let-7i had high positive correlation with anti-cancer immune signatures in HGSC patients. Confirming this role, enforced Let-7i expression in murine HGSC tumours resulted in a significant decrease in tumour burden with a significant increase in tumour T cell numbers in tumours. In concert with the improved tumoural immunity, Let-7i treatment also significantly increased CD86 expression in antigen presenting cells (APCs) in the draining lymph nodes, indicating enhanced APC activity. Collectively, our findings highlight an important role of Let-7i in anti-tumour immunity and its potential use for inducing an anti-tumour effect in HGSC.

Enhancement of Immune Response of Bioconjugate Nanovaccine by Loading of CpG through Click Chemistry

CpG is a widely used adjuvant that enhances the cellular immune response by entering antigen-presenting cells and binding with receptors. The traditional physical mixing of the antigen and CpG adjuvant results in a low adjuvant utilization rate. Considering the efficient delivery capacity of nanovaccines, we developed an attractive strategy to covalently load CpG onto the nanovaccine, which realized the co-delivery of both CpG and the antigen. Briefly, the azide-modified CpG was conjugated to a bioconjugate nanovaccine (NP-OPS) against Shigella flexneri through a simple two-step reaction. After characterization of the novel vaccine (NP-OPS-CpG), a series of in vitro and in vivo experiments were performed, including in vivo imaging, lymph node sectioning, and dendritic cell stimulation, and the results showed that more CpG reached the lymph nodes after covalent coupling. Subsequent flow cytometry analysis of lymph nodes from immunized mice showed that the cellular immune response was greatly promoted by the nanovaccine coupled with CpG. Moreover, by analyzing the antibody subtypes of immunized mice, NP-OPS-CpG was found to further promote a Th1-biased immune response. Thus, we developed an attractive method to load CpG on a nanovaccine that is simple, convenient, and is especially suitable for immune enhancement of vaccines against intracellular bacteria.

Locoregional Lymphatic Delivery Systems Using Nanoparticles and Hydrogels for Anticancer Immunotherapy

The lymphatic system has gained significant interest as a target tissue to control cancer progress, which highlights its central role in adaptive immune response. Numerous mechanistic studies have revealed the benefits of nano-sized materials in the transport of various cargos to lymph nodes, overcoming barriers associated with lymphatic physiology. The potential of sustained drug delivery systems in improving the therapeutic index of various immune modulating agents is also being actively discussed. Herein, we aim to discuss design rationales and principles of locoregional lymphatic drug delivery systems for invigorating adaptive immune response for efficient antitumor immunotherapy and provide examples of various advanced nanoparticle- and hydrogel-based formulations.

Universal and Translational Nanoparticulate CpG Adjuvant

CpG, an agonist of toll-like receptor 9 (TLR9), has become a novel adjuvant that substantially potentiates cellular immunity. However, this agonist may increase systemic toxicity by diffusing into blood after administration and is difficult to be internalized by immune cells to reach TLR9 located in endosomes as a result of the characteristics of negative charge of CpG. Here, we applied a scalable and controllable flash nanocomplexation technology to prepare nanoparticulate CpG adjuvant (npCpG), CpG encapsulated in a physical cross-linking network of protamine and TPP. The nanoadjuvant could redirect CpG into draining lymph nodes to reduce systemic diffusion to improve safety. Further, a combination of npCpG and influenza H1N1 hemagglutinin antigen showed excellent humoral and cellular immunity, evoking high levels of antibodies and cytokines and inducing a great expansion of splenocytes in immunized mice. Also, the nanoadjuvant combined with ovalbumin antigen led to a potent cytotoxic T-cell response, substantially inhibited tumor growth, and improved the survival rate of mice in a melanoma model. This study showed the universal performances of npCpG in infectious disease prevention and tumor immunotherapy to demonstrate the translational potential.

Reduction-Sensitive Protein Nanogels Enhance Uptake of Model and Tumor Lysate Antigens In Vitro by Mouse- and Human-Derived Dendritic Cells

Peptides and proteins represent an emerging class of powerful therapeutics. Peptide and protein nanogels are attractive carriers for the transport and delivery of biologically active peptides and proteins because they allow essentially quantitative encapsulation of these biologics. One interesting field of use of peptide and protein nanogels is the transport of antigens and adjuvants in cancer immunotherapy. This study demonstrates the use of reduction-sensitive protein nanogels for the delivery of ovalbumin and oxidized tumor lysate-based antigens to mouse and human-donor-derived dendritic cells. Challenging mouse-derived and human dendritic cells with reduction-sensitive ovalbumin nanogels was found to significantly enhance antigen uptake as compared to the use of the corresponding free protein antigen. The experiments with mouse-derived dendritic cells further showed that the administration of ovalbumin in the form of reduction-sensitive nanogels enhanced dendritic cell maturation as well as the presentation of the SIINFEKL epitope as compared to experiments that use free ovalbumin. In addition to ovalbumin as a model antigen, the feasibility of reduction-sensitive nanogels was also demonstrated for the delivery of oxidized, whole tumor lysate-based cancer antigens. In experiments with dendritic cells harvested from human donors, dendritic cell uptake of the oxidized tumor lysate antigen was significantly enhanced in experiments that used oxidized tumor lysate nanogels as compared to the free antigen.

Immunopotentiation by Lymph-Node Targeting of a Malaria Transmission-Blocking Nanovaccine

A successful malaria transmission blocking vaccine (TBV) requires the induction of a high antibody titer that leads to abrogation of parasite traversal of the mosquito midgut following ingestion of an infectious bloodmeal, thereby blocking the cascade of secondary human infections. Previously, we developed an optimized construct UF6b that elicits an antigen-specific antibody response to a neutralizing epitope of Anopheline alanyl aminopeptidase N (AnAPN1), an evolutionarily conserved pan-malaria mosquito midgut-based TBV target, as well as established a size-controlled lymph node targeting biodegradable nanoparticle delivery system that leads to efficient and durable antigen-specific antibody responses using the model antigen ovalbumin. Herein, we demonstrate that co-delivery of UF6b with the adjuvant CpG oligodeoxynucleotide immunostimulatory sequence (ODN ISS) 1018 using this biodegradable nanoparticle vaccine delivery system generates an AnAPN1-specific immune response that blocks parasite transmission in a standard membrane feeding assay. Importantly, this platform allows for antigen dose-sparing, wherein lower antigen payloads elicit higher-quality antibodies, therefore less antigen-specific IgG is needed for potent transmission-reducing activity. By targeting lymph nodes directly, the resulting immunopotentiation of AnAPN1 suggests that the de facto assumption that high antibody titers are needed for a TBV to be successful needs to be re-examined. This nanovaccine formulation is stable at -20°C storage for at least 3 months, an important consideration for vaccine transport and distribution in regions with poor healthcare infrastructure. Together, these data support further development of this nanovaccine platform for malaria TBVs.

Nanobiomaterial-based vaccination immunotherapy of cancer

Cancer immunotherapies including cancer vaccines, immune checkpoint blockade or chimeric antigen receptor T cells have been exploited as the attractive treatment modalities in recent years. Among these approaches, cancer vaccines that designed to deliver tumor antigens and adjuvants to activate the antigen presenting cells (APCs) and induce antitumor immune responses, have shown significant efficacy in inhibiting tumor growth, preventing tumor relapse and metastasis. Despite the potential of cancer vaccination strategies, the therapeutic outcomes in preclinical trials are failed to promote their clinical translation, which is in part due to their inefficient vaccination cascade of five critical steps: antigen identification, antigen encapsulation, antigen delivery, antigen release and antigen presentation to T cells. In recent years, it has been demonstrated that various nanobiomaterials hold great potential to enhance cancer vaccination cascade and improve their antitumor performance and reduce the off-target effect. We summarize the cutting-edge advances of nanobiomaterials-based vaccination immunotherapy of cancer in this review. The various cancer nanovaccines including antigen peptide/adjuvant-based nanovaccines, nucleic acid-based nanovaccines as well as biomimetic nanobiomaterials-based nanovaccines are discussed in detail. We also provide some challenges and perspectives associated with the clinical translation of cancer nanovaccines.

Synthetic Particles for Cancer Vaccines: Connecting the Inherent Supply Chain

Cancer vaccines have opened a new paradigm for safe and effective antitumor therapy, but they still suffer from shortcomings such as insufficient immunogenicity and immune tolerance, which seldom makes them the first choice in clinic. In fact, similar to providing a high-end product, a robust antitumor effect depends on the inherent supply chain, which attains, processes, and presents tumor-associated antigens via antigen presenting cells to T cells, which then leads to lysis of the cancer cells to release more antigens to complete the supply chain. Under these circumstances, the failure of cancer vaccines can be treated as a blockade or chain rupture. Thus, for effective tumor treatment, the key is to rationally design logistic systems to restore the supply chain.Under these circumstances, this Account summarizes our recent attempts to exploit the immunogenic trait of synthetic particles to enhance the distribution, presentation, and immune activations of the whole priming process in cancer vaccines: (1) Raw material (tumor antigen/signals) procurement: We illustrated the efforts to deliver antigens to antigen presenting cells (APCs) and draining lymph nodes for potent internalizations, and put more emphasis on the structural effect of sizes, charges, shapes, and assembly strategies for the antigen depot, lymph node transfer, and APC endocytosis. (2) Manufacture of cytotoxic T lymphocytes (CTLs) via APC recognition and presentation: We centered on exploiting the softness of two-dimensional graphene and Pickering emulsions to dynamically potentiate the immune recognition, and demonstrating the recent advances in lysosome escape strategies for enhanced antigen cross-presentations. (3) Marketing the accumulations of CTLs and the reversal of an immunosuppressive microenvironment within the tumor: We demonstrated the previous attempts to inherently cultivate the tumor tropism of the T cells via the multiantigenic repertoire and discussed the advances and challenges of combinatory cancer vaccines with an immune checkpoint blockade to reinforce the antitumor efficacy. Collectively, this Account aims to illustrate the potential of the particulate cancer vaccines to recapitalize the inherent host immune responses for the maximum antitumor effect. And by integrating the antitumor supply chain, optimized synthetic particles may shed light on the development of safe and effective particulate cancer vaccines.

Cell and tissue engineering in lymph nodes for cancer immunotherapy

In cancer, lymph nodes (LNs) coordinate tumor antigen presentation necessary for effective antitumor immunity, both at the levels of local cellular interactions and tissue-level organization. In this review, we examine how LNs may be engineered to improve the therapeutic outcomes of cancer immunotherapy. At the cellular scale, targeting the LNs impacts the potency of cancer vaccines, immune checkpoint blockade, and adoptive cell transfer. On a tissue level, macro-scale biomaterials mimicking LN features can function as immune niches for cell reprogramming or delivery in vivo, or be utilized in vitro to enable preclinical testing of drugs and vaccines. We additionally review strategies to induce ectopic lymphoid sites reminiscent of LNs that may improve antitumor T cell priming.

Highly efficient cascading synergy of cancer photo-immunotherapy enabled by engineered graphene quantum dots/photosensitizer/CpG oligonucleotides hybrid nanotheranostics

Currently, photoimmunotherapy based on a theranostic nanoplatform emerges as a promising modality in advanced cancer therapy. In this study, a new type of versatile nanoassemblies (denoted as PC@GCpD(Gd)) was rationally designed by integrating the polydopamine stabilized graphene quantum dots (GQD)-photosensitizer nanocomposites (denoted as GCpD), immunostimulatory polycationic polymer/CpG oligodeoxynucleotide (CpG ODN) nanoparticles (denoted as PC) and Gd³⁺/Cy3 imaging probes for dual magnetic resonance/fluorescence imaging-guided photoimmunotherapy. PC@GCpD(Gd) effectively killed the tumor cells through the amplified photothermal and photodynamic effects mediated by GCpD, and contemporaneously delivered CpG ODN to the targeted endosomal Toll-like receptor 9 (TLR9) to continuously stimulate the secretion of proinflammatory cytokines and the maturation of dendritic cells, thereby resulting in the activation and infiltration of T lymphocytes. As a result, PC@GCpD(Gd) achieved robust inhibition efficiency to almost completely suppress the EMT6 murine mammary cancer model under laser irradiation, implying the superior synergy of combined photoimmunotherapy. Moreover, the in vivo delivery and biodistribution of PC@GCpD(Gd) could be tracked using the high-quality bimodal magnetic resonance imaging/fluorescence imaging. This study highlighted the potent prospect of hybrid PC@GCpD(Gd) nanoassemblies for precise cancer photoimmunotherapy with a cascading effect.