The effect of PEGylation on the efficacy and uptake of an immunostimulatory nanoparticle in the tumor immune microenvironment

Mesoporous Silica Nanoparticles as an Ideal Platform for Cancer Immunotherapy: Recent Advances and Future Directions

Cancer immunotherapy recently transforms the traditional approaches against various cancer malignancies. Immunotherapy includes systemic and local treatments to enhance immune responses against cancer and involves strategies such as immune checkpoints, cancer vaccines, immune modulatory agents, mimetic antigen-presenting cells, and adoptive cell therapy. Despite promising results, these approaches still suffer from several limitations including lack of precise delivery of immune-modulatory agents to the target cells and off-target toxicity, among others, that can be overcome using nanotechnology. Mesoporous silica nanoparticles (MSNs) are investigated to improve various aspects of cancer immunotherapy attributed to the advantageous structural features of this nanomaterial. MSNs can be engineered to alter their properties such as size, shape, porosity, surface functionality, and adjuvanticity. This review explores the immunological properties of MSNs and the use of MSNs as delivery vehicles for immune-adjuvants, vaccines, and mimetic antigen-presenting cells (APCs). The review also details the current strategies to remodel the tumor microenvironment to positively reciprocate toward the anti-tumor immune cells and the use of MSNs for immunotherapy in combination with other anti-tumor therapies including photodynamic/thermal therapies to enhance the therapeutic effect against cancer. Last, the present demands and future scenarios for the use of MSNs for cancer immunotherapy are discussed.

Engineering approaches for innate immune-mediated tumor microenvironment remodeling

Cancer immunotherapy offers transformative promise particularly for the treatment of lethal cancers, since a correctly trained immune system can comprehensively orchestrate tumor clearance with no need for continued therapeutic intervention. Historically, the majority of immunotherapies have been T cell-focused and have included immune checkpoint inhibitors, chimeric antigen receptor T cells, and T-cell vaccines. Unfortunately T-cell-focused therapies have failed to achieve optimal efficacy in most solid tumors largely because of a highly immunosuppressed 'cold' or immune-excluded tumor microenvironment (TME). Recently, a rapidly growing treatment paradigm has emerged that focuses on activation of tumor-resident innate antigen-presenting cells, such as dendritic cells and macrophages, which can drive a proinflammatory immune response to remodel the TME from 'cold' or immune-excluded to 'hot'. Early strategies for TME remodeling centered on free cytokines and agonists, but these approaches have faced significant hurdles in both delivery and efficacy. Systemic toxicity from off-target inflammation is a paramount concern in these therapies. To address this critical gap, engineering approaches have provided the opportunity to add 'built-in' capabilities to cytokines, agonists, and other therapeutic agents to mediate improved delivery and efficacy. Such capabilities have included protective encapsulation to shield them from degradation, targeting to direct them with high specificity to tumors, and co-delivery strategies to harness synergistic proinflammatory pathways. Here, we review innate immune-mediated TME remodeling engineering approaches that focus on cytokines, innate immune agonists, immunogenic viruses, and cell-based methods, highlighting emerging preclinical approaches and strategies that are either being tested in clinical trials or already Food and Drug Administration approved.

Overcoming challenges in the delivery of STING agonists for cancer immunotherapy: A comprehensive review of strategies and future perspectives

STING (Stimulator of Interferon Genes) agonists have emerged as promising agents in the field of cancer immunotherapy, owing to their excellent capacity to activate the innate immune response and combat tumor-induced immunosuppression. This review provides a comprehensive exploration of the strategies employed to develop effective formulations for STING agonists, with particular emphasis on versatile nano-delivery systems. The recent advancements in delivery systems based on lipids, natural/synthetic polymers, and proteins for STING agonists are summarized. The preparation methodologies of nanoprecipitation, self-assembly, and hydrogel, along with their advantages and disadvantages, are also discussed. Furthermore, the challenges and opportunities in developing next-generation STING agonist delivery systems are elaborated. This review aims to serve as a reference for researchers in designing novel and effective STING agonist delivery systems for cancer immunotherapy.

Nanomedicine Strategies for Targeting Tumor Stroma

The tumor stroma, or the microenvironment surrounding solid tumors, can significantly impact the effectiveness of cancer therapies. The tumor microenvironment is characterized by high interstitial pressure, a consequence of leaky vasculature, and dense stroma created by excessive deposition of various macromolecules such as collagen, fibronectin, and hyaluronic acid (HA). In addition, non-cancerous cells such as cancer-associated fibroblasts (CAFs) and the extracellular matrix (ECM) itself can promote tumor growth. In recent years, there has been increased interest in combining standard cancer treatments with stromal-targeting strategies or stromal modulators to improve therapeutic outcomes. Furthermore, the use of nanomedicine, which can improve the delivery and retention of drugs in the tumor, has been proposed to target the stroma. This review focuses on how different stromal components contribute to tumor progression and impede chemotherapeutic delivery. Additionally, this review highlights recent advancements in nanomedicine-based stromal modulation and discusses potential future directions for developing more effective stroma-targeted cancer therapies.

STING agonist-loaded mesoporous manganese-silica nanoparticles for vaccine applications

Cyclic dinucleotides (CDNs), as one type of Stimulator of Interferon Genes (STING) pathway agonist, have shown promising results for eliciting immune responses against cancer and viral infection. However, the suboptimal drug-like properties of conventional CDNs, including their short in vivo half-life and poor cellular permeability, compromise their therapeutic efficacy. In this study, we have developed a manganese-silica nanoplatform (MnOx@HMSN) that enhances the adjuvant effects of CDN by achieving synergy with Mn2+ for vaccination against cancer and SARS-CoV-2. MnOx@HMSN with large mesopores were efficiently co-loaded with CDN and peptide/protein antigens. MnOx@HMSN(CDA) amplified the activation of the STING pathway and enhanced the production of type-I interferons and other proinflammatory cytokines from dendritic cells. MnOx@HMSN(CDA) carrying cancer neoantigens elicited robust antitumor T-cell immunity with therapeutic efficacy in two different murine tumor models. Furthermore, MnOx@HMSN(CDA) loaded with SARS-CoV-2 antigen achieved strong and durable (up to one year) humoral immune responses with neutralizing capability. These results demonstrate that MnOx@HMSN(CDA) is a versatile nanoplatform for vaccine applications.

Emerging Trends in Nano-Driven Immunotherapy for Treatment of Cancer

Despite advancements in the development of anticancer medications and therapies, cancer still has the greatest fatality rate due to a dismal prognosis. Traditional cancer therapies include chemotherapy, radiotherapy, and targeted therapy. The conventional treatments have a number of shortcomings, such as a lack of selectivity, non-specific cytotoxicity, suboptimal drug delivery to tumour locations, and multi-drug resistance, which results in a less potent/ineffective therapeutic outcome. Cancer immunotherapy is an emerging and promising strategy to elicit a pronounced immune response against cancer. Immunotherapy stimulates the immune system with cancer-specific antigens or immune checkpoint inhibitors to overcome the immune suppressive tumour microenvironment and kill the cancer cells. However, delivery of the antigen or immune checkpoint inhibitors and activation of the immune response need to circumvent the issues pertaining to short lifetimes and effect times, as well as adverse effects associated with off-targeting, suboptimal, or hyperactivation of the immune system. Additional challenges posed by the tumour suppressive microenvironment are less tumour immunogenicity and the inhibition of effector T cells. The evolution of nanotechnology in recent years has paved the way for improving treatment efficacy by facilitating site-specific and sustained delivery of the therapeutic moiety to elicit a robust immune response. The amenability of nanoparticles towards surface functionalization and tuneable physicochemical properties, size, shape, and surfaces charge have been successfully harnessed for immunotherapy, as well as combination therapy, against cancer. In this review, we have summarized the recent advancements made in choosing different nanomaterial combinations and their modifications made to enable their interaction with different molecular and cellular targets for efficient immunotherapy. This review also highlights recent trends in immunotherapy strategies to be used independently, as well as in combination, for the destruction of cancer cells, as well as prevent metastasis and recurrence.

Nanotechnology-based diagnostics and therapeutics in acute lymphoblastic leukemia: a systematic review of preclinical studies

Background: Leukemia is a malignant disease that threatens human health and life. Nano-delivery systems improve drug solubility, bioavailability, and blood circulation time, and release drugs selectively at desired sites using targeting or sensing strategies. As drug carriers, they could improve therapeutic outcomes while reducing systemic toxicity. They have also shown promise in improving leukemia detection and diagnosis. The study aimed to assess the potential of nanotechnology-based diagnostics and therapeutics in preclinical human acute lymphoblastic leukemia (h-ALL). Methods: We performed a systematic search through April 2022. Articles written in English reporting the toxicity, efficacy, and safety of nanotechnology-based drugs (in the aspect of treatment) and specificity, limit of detection (LOD), or sensitivity (in the aspect of the detection field) in preclinical h-ALL were included. The study was performed according to PRISMA instructions. The methodological quality was assessed using the QualSyst tool. Results: A total of 63 original articles evaluating nanotechnology-based therapeutics and 35 original studies evaluating nanotechnology-based diagnostics were included in this review. As therapeutics in ALL, nanomaterials offer controlled release, targeting or sensing ligands, targeted gene therapy, photodynamic therapy and photothermic therapy, and reversal of multidrug-resistant ALL. A narrative synthesis of studies revealed that nanoparticles improve the ratio of efficacy to the toxicity of anti-leukemic drugs. They have also been developed as a vehicle for biomolecules (such as antibodies) that can help detect and monitor leukemic biomarkers. Therefore, nanomaterials can help with early diagnostics and personalized treatment of ALL. Conclusion: This review discussed nanotechnology-based preclinical strategies to achieve ALL diagnosis and therapy advancement. This involves modern drug delivery apparatuses and detection devices for prompt and targeted disease diagnostics. Nonetheless, we are yet in the experimental phase and investigational stage in the field of nanomedicine, with many features remained to be discovered as well as numerous problems to be solved.

Nanobubble-based anti-hepatocellular carcinoma therapy combining immune check inhibitors and sonodynamic therapy

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, posing a global threat to human healthcare, and current approved treatment strategies do not produce satisfactory outcomes. Here, nanobubbles (NBs) were prepared that carried Immune Check Inhibitors (ICIs), PD-L1 antibody (PD-L1 Ab) and sonodynamic agent CHLORIN E6 (Ce₆); the anti-cancer properties of these NBs were analyzed from the point of view of immune and sonodynamic therapies. The PD-L1 Ab/Ce₆-NBs could inhibit tumor growth through regulating reactive oxygen species (ROS) production, apoptosis, and most importantly, the function of associated immunocytes, including natural killer cells and lymphocytes. The tumor tissues highly expressed markers of immunogenic tumor cell death (ICD) in which the expression of calreticulin (CRT) and ICD-related immune cytokines (CD80, CD86, INF-γ, and IL-2) were increased in PD-L1 Ab/Ce₆-NB treated mice. PD-L1 Ab/Ce₆-NBs also promoted murine spleen lymphocyte proliferation and cytotoxic activity, as well as CD8+ T cell infiltration in the tumor tissues, and downregulation of the PD-L1 protein and mRNA expression. Furthermore, Bax expression was increased and Bcl-2 was inhibited at the mRNA and protein levels in a murine subcutaneous transplanted tumor model. These results indicate that PD-L1 Ab/Ce₆-NBs can induce ROS-dependent ICD to further boost anti-cancer immune responses under the action of targeting the PD-1/PD-L1 immune check point in the tumor microenvironment as a promising therapeutic agent for HCC.

Clickable Biomaterials for Modulating Neuroinflammation

Crosstalk between the nervous and immune systems in the context of trauma or disease can lead to a state of neuroinflammation or excessive recruitment and activation of peripheral and central immune cells. Neuroinflammation is an underlying and contributing factor to myriad neuropathologies including neurodegenerative diseases like Alzheimer's disease and Parkinson's disease; autoimmune diseases like multiple sclerosis; peripheral and central nervous system infections; and ischemic and traumatic neural injuries. Therapeutic modulation of immune cell function is an emerging strategy to quell neuroinflammation and promote tissue homeostasis and/or repair. One such branch of 'immunomodulation' leverages the versatility of biomaterials to regulate immune cell phenotypes through direct cell-material interactions or targeted release of therapeutic payloads. In this regard, a growing trend in biomaterial science is the functionalization of materials using chemistries that do not interfere with biological processes, so-called 'click' or bioorthogonal reactions. Bioorthogonal chemistries such as Michael-type additions, thiol-ene reactions, and Diels-Alder reactions are highly specific and can be used in the presence of live cells for material crosslinking, decoration, protein or cell targeting, and spatiotemporal modification. Hence, click-based biomaterials can be highly bioactive and instruct a variety of cellular functions, even within the context of neuroinflammation. This manuscript will review recent advances in the application of click-based biomaterials for treating neuroinflammation and promoting neural tissue repair.

Emerging advances in nanomedicine for breast cancer immunotherapy: opportunities and challenges

Breast cancer is one of the most common causes of cancer-related morbidity and mortality in women worldwide. Early diagnosis and an appropriate therapeutic approach for all cancers are climacterics for a favorable prognosis. Targeting the immune system in breast cancer is already a clinical reality with notable successes, specifically with checkpoint blockade antibodies and chimeric antigen receptor T-cell therapy. However, there have been inevitable setbacks in the clinical application of cancer immunotherapy, including inadequate immune responses due to insufficient delivery of immunostimulants to immune cells and uncontrolled immune system modulation. Rapid advancements and new evidence have suggested that nanomedicine-based immunotherapy may be a viable option for treating breast cancer.

Comparison of the uptake of untargeted and targeted immunostimulatory nanoparticles by immune cells in the microenvironment of metastatic breast cancer

To alter the immunosuppressive tumor microenvironment (TME), we developed an immunostimulatory nanoparticle (NP) to reprogram a tumor's dysfunctional and inhibitory antigen-presenting cells (APCs) into properly activated APCs that stimulate tumor-reactive cytotoxic T cells. Importantly, systemic delivery allowed NPs to efficiently utilize the entire microvasculature and gain access into the majority of the perivascular TME, which coincided with the APC-rich tumor areas leading to uptake of the NPs predominantly by APCs. In this work, a 60 nm NP was loaded with a STING agonist, which triggered robust production of interferon β, resulting in activation of APCs. In addition to untargeted NPs, we employed 'mainstream' ligands targeting fibronectin, αvβ3 integrin and P-selectin that are commonly used to direct nanoparticles to tumors. Using the 4T1 mouse model, we assessed the microdistribution of the four NP variants in the tumor immune microenvironment in three different breast cancer landscapes, including primary tumor, early metastasis, and late metastasis. The different NP variants resulted in variable uptake by immune cell subsets depending on the organ and tumor stage. Among the NP variants, therapeutic studies indicated that the untargeted NPs and the integrin-targeting NPs exhibited a remarkable short- and long-term immune response and long-lasting antitumor effect.

Targeting innate immune system by nanoparticles for cancer immunotherapy

Various cancer therapies have advanced remarkably over the past decade. Unlike the direct therapeutic targeting of tumor cells, cancer immunotherapy is a new strategy that boosts the host's immune system...