Spatio-temporal delivery of both intra- and extracellular toll-like receptor agonists for enhancing antigen-specific immune responses

Multifunctional Nanoparticle-Loaded Injectable Alginate Hydrogels with Deep Tumor Penetration for Enhanced Chemo-Immunotherapy of Cancer

Chemo-immunotherapy has become a promising strategy for cancer treatment. However, the inability of the drugs to penetrate deeply into the tumor and form potent tumor vaccines in vivo severely restricts the antitumor effect of chemo-immunotherapy. In this work, an injectable sodium alginate platform is reported to promote penetration of the chemotherapeutic doxorubicin (DOX) and delivery of personalized tumor vaccines. The injectable multifunctional sodium alginate platform cross-links rapidly in the presence of physiological concentrations of Ca2+, forming a hydrogel that acts as a drug depot and releases loaded hyaluronidase (HAase), DOX, and micelles (IP-NPs) slowly and sustainedly. By degrading hyaluronic acid (HA) overexpressed in tumor tissue, HAase can make tumor tissue "loose" and favor other components to penetrate deeply. DOX induces potent immunogenic cell death (ICD) and produces tumor-associated antigens (TAAs), which could be effectively captured by polyethylenimine (PEI) coated IP-NPs micelles and form personalized tumor vaccines. The vaccines efficaciously facilitate the maturation of dendritic cells (DCs) and activation of T lymphocytes, thus producing long-term immune memory. Imiquimod (IMQ) loaded in the core could further activate the immune system and trigger a more robust antitumor immune effect. Hence, the research proposes a multifunctional drug delivery platform for the effective treatment of colorectal cancer.

Rational Design of Lipid-Based Vectors for Advanced Therapeutic Vaccines

Recent advancements in vaccine delivery systems have seen the utilization of various materials, including lipids, polymers, peptides, metals, and inorganic substances, for constructing non-viral vectors. Among these, lipid-based nanoparticles, composed of natural, synthetic, or physiological lipid/phospholipid materials, offer significant advantages such as biocompatibility, biodegradability, and safety, making them ideal for vaccine delivery. These lipid-based vectors can protect encapsulated antigens and/or mRNA from degradation, precisely tune chemical and physical properties to mimic viruses, facilitate targeted delivery to specific immune cells, and enable efficient endosomal escape for robust immune activation. Notably, lipid-based vaccines, exemplified by those developed by BioNTech/Pfizer and Moderna against COVID-19, have gained approval for human use. This review highlights rational design strategies for vaccine delivery, emphasizing lymphoid organ targeting and effective endosomal escape. It also discusses the importance of rational formulation design and structure-activity relationships, along with reviewing components and potential applications of lipid-based vectors. Additionally, it addresses current challenges and future prospects in translating lipid-based vaccine therapies for cancer and infectious diseases into clinical practice.

Tumor Microenvironment-Responsive Nanoparticles Amplifying STING Signaling Pathway for Cancer Immunotherapy

Insufficient activation of the stimulator of interferon genes (STING) signaling pathway and profoundly immunosuppressive microenvironment largely limits the effect of cancer immunotherapy. Herein, tumor microenvironment (TME)-responsive nanoparticles (PMM NPs) are exploited that simultaneously harness STING and Toll-like receptor 4 (TLR4) to augment STING activation via TLR4-mediated nuclear factor-kappa B signaling pathway stimulation, leading to the increased secretion of type I interferons (i.e., 4.0-fold enhancement of IFN-β) and pro-inflammatory cytokines to promote a specific T cell immune response. Moreover, PMM NPs relieve the immunosuppression of the TME by decreasing the percentage of regulatory T cells, and polarizing M2 macrophages to the M1 type, thus creating an immune-supportive TME to unleash a cascade adaptive immune response. Combined with an anti-PD-1 antibody, synergistic efficacy is achieved in both inflamed colorectal cancer and noninflamed metastatic breast tumor models. Moreover, rechallenging tumor-free animals with homotypic cells induced complete tumor rejection, indicating the generation of systemic antitumor memory. These TME-responsive nanoparticles may open a new avenue to achieve the spatiotemporal orchestration of STING activation, providing a promising clinical candidate for next-generation cancer immunotherapy.

Enhanced Chemo-Immunotherapy Strategy Utilizing Injectable Thermosensitive Hydrogel for The Treatment of Diffuse Peritoneal Metastasis in Advanced Colorectal Cancer

Patients with colorectal cancer (CRC) and diffuse peritoneal metastasis (PM) are not eligible for surgical intervention. Thus, palliative treatment remains the standard of care in clinical practice. Systemic chemotherapy fails to cause drug accumulation at the lesion sites, while intraperitoneal chemotherapy (IPC) is limited by high clearance rates and associated complications. Given the poor prognosis, a customized OxP/R848@PLEL hydrogel delivery system has been devised to improve the clinical benefit of advanced CRC with diffuse PM. This system is distinguished by its simplicity, security, and efficiency. Specifically, the PLEL hydrogel exhibits excellent injectability and thermosensitivity, enabling the formation of drug depots within the abdominal cavity, rendering it an optimal carrier for IPC. Oxaliplatin (OxP), a first-line drug for advanced CRC, is cytotoxic and enhances the immunogenicity of tumors by inducing immunogenic cell death. Furthermore, OxP and resiquimod (R848) synergistically enhance the maturation of dendritic cells, promote the expansion of cytotoxic T lymphocytes, and induce the formation of central memory T cells. Moreover, R848 domesticates macrophages to an anti-tumor phenotype. OxP/R848@PLEL effectively eradicates peritoneal metastases, completely inhibits ascites production, and significantly prolongs mice lifespan. As such, it provides a promising approach to managing diffuse PM in patients with CRC without surgical indications.

Lipid-based nanoparticles as drug delivery systems for cancer immunotherapy

Immune checkpoint inhibitors (ICIs) have shown remarkable success in cancer treatment. However, in cancer patients without sufficient antitumor immunity, numerous data indicate that blocking the negative signals elicited by immune checkpoints is ineffective. Drugs that stimulate immune activation-related pathways are emerging as another route for improving immunotherapy. In addition, the development of nanotechnology presents a promising platform for tissue and cell type-specific delivery and improved uptake of immunomodulatory agents, ultimately leading to enhanced cancer immunotherapy and reduced side effects. In this review, we summarize and discuss the latest developments in nanoparticles (NPs) for cancer immuno-oncology therapy with a focus on lipid-based NPs (lipid-NPs), including the characteristics and advantages of various types. Using the agonists targeting stimulation of the interferon genes (STING) transmembrane protein as an exemplar, we review the potential of various lipid-NPs to augment STING agonist therapy. Furthermore, we present recent findings and underlying mechanisms on how STING pathway activation fosters antitumor immunity and regulates the tumor microenvironment and provide a summary of the distinct STING agonists in preclinical studies and clinical trials. Ultimately, we conduct a critical assessment of the obstacles and future directions in the utilization of lipid-NPs to enhance cancer immunotherapy.

Engineered Nanoprobes for Immune Activation Monitoring

The activation of the immune system is critical for cancer immunotherapy and treatments of inflammatory diseases. Non-invasive visualization of immunoactivation is designed to monitor the dynamic nature of the immune response and facilitate the assessment of therapeutic outcomes, which, however, remains challenging. Conventional imaging modalities, such as positron emission tomography, computed tomography, etc., were utilized for imaging immune-related biomarkers. To explore the dynamic immune monitoring, probes with signals correlated to biomarkers of immune activation or prognosis are urgently needed. These emerging molecular probes, which turn on the signal only in the presence of the intended biomarker, can improve the detection specificity. These probes with "turn on" signals enable non-invasive, dynamic, and real-time imaging with high sensitivity and efficiency, showing significance for multifunctionality/multimodality imaging. As a result, more and more innovative engineered nanoprobes combined with diverse imaging modalities were developed to assess the activation of the immune system. In this work, we comprehensively review the recent and emerging advances in engineered nanoprobes for monitoring immune activation in cancer or other immune-mediated inflammatory diseases and discuss the potential in predicting the efficacy following treatments. Research on real-time in vivo immunoimaging is still under exploration, and this review can provide guidance and facilitate the development and application of next-generation imaging technologies.