Eliciting Immunogenic Cell Death via a Unitized Nanoinducer

Self-Delivery Nanobooster to Enhance Immunogenic Cell Death for Cancer Chemoimmunotherapy

Inducing immunogenic cell death (ICD) is a promising strategy for cancer immunotherapy. Shikonin (SHK), a naphthoquinone compound from Lithospermum erythrorhizon, can stimulate antitumor immunity by inducing ICD. Nevertheless, the immunogenicity of tumor cells killed by SHK is weak. Endoplasmic reticulum (ER) stress is an important intracellular pathway of the ICD effect. Curcumin (CUR) can directly induce ER stress by disrupting Ca2+ homeostasis, which might enhance SHK-induced ICD effect. A self-delivery ICD effect nanobooster (CS-PEG NPs) was developed by the self-assembly of SHK (ICD inducer) and CUR (ICD enhancer) with the assistance of DSPE-PEG2K for cancer chemoimmunotherapy. CS-PEG NPs possessed effective CT26 tumor cell cellular uptake and tumor accumulation ability. Moreover, enhanced cytotoxicity against tumor cells and apoptosis promotion were achieved due to the synergistic effect of CUR and SHK. Notably, CS-PEG NPs induced obvious Ca2+ homeostasis disruption, ER stress, and ICD effect. Subsequently, the neoantigens produced by the robust ICD effect in vivo promoted dendritic cell maturation, which further recruited and activated cytotoxic T lymphocytes. Superior antitumor efficacy and systemic antitumor immunity were observed in the CT26-bearing BALB/c mouse model without side effects in major organs. This study offers a promising self-delivery nanobooster to induce strong ICD effect and antitumor immunity for cancer chemoimmunotherapy.

Targeting Hydrogel for Intelligent Recognition and Spatiotemporal Control in Cell-Based Therapeutics

Smart drug platforms based on spatiotemporally controlled release and integration of tumor imaging are expected to overcome the inefficiency and uncertainty of traditional theranostic modes. In this study, a composite consisting of a thermosensitive hydrogel (polyvinyl alcohol-carboxylic acid hydrogel (PCF)) and a multifunctional nanoparticle (Fe3O4@Au/Mn(Zn)-4-carboxyphenyl porphyrin/polydopamine (FAMxP)) is developed to combine tumor immunogenic cell death (ICD)/immune checkpoint blockade (ICB) therapy under the guidance of magnetic resonance imaging (MRI) and fluorescence imaging (FI). It can not only further recognize the target cells through the folate receptor of tumor cells, but also produce thermal dissolution after exposure to near-infrared light to slowly release FAMxP in situ, thereby prolonging the treatment time and avoiding tumor recurrence. As FAMxP entered the tumor cells, it released FAMx in a pH-dependent manner. Chemodynamic, photothermal and photodynamic therapy can cause significant ICD in cancer cells. ICB can thus be further enhanced by injecting anti-programmed cell death ligand 1, improving the effectiveness of tumor treatment. The developed PCF-FAMxP composite hydrogel may represent an updated drug design approach with simple compositions for cooperative MRI/FI-guided targeted therapeutic pathways for tumors.

Engineering nanomedicines for immunogenic eradication of cancer cells: Recent trends and synergistic approaches

Resistance to cancer immunotherapy is mainly attributed to poor tumor immunogenicity as well as the immunosuppressive tumor microenvironment (TME) leading to failure of immune response. Numerous therapeutic strategies including chemotherapy, radiotherapy, photodynamic, photothermal, magnetic, chemodynamic, sonodynamic and oncolytic therapy, have been developed to induce immunogenic cell death (ICD) of cancer cells and thereby elicit immunogenicity and boost the antitumor immune response. However, many challenges hamper the clinical application of ICD inducers resulting in modest immunogenic response. Here, we outline the current state of using nanomedicines for boosting ICD of cancer cells. Moreover, synergistic approaches used in combination with ICD inducing nanomedicines for remodeling the TME via targeting immune checkpoints, phagocytosis, macrophage polarization, tumor hypoxia, autophagy and stromal modulation to enhance immunogenicity of dying cancer cells were analyzed. We further highlight the emerging trends of using nanomaterials for triggering amplified ICD-mediated antitumor immune responses. Endoplasmic reticulum localized ICD, focused ultrasound hyperthermia, cell membrane camouflaged nanomedicines, amplified reactive oxygen species (ROS) generation, metallo-immunotherapy, ion modulators and engineered bacteria are among the most innovative approaches. Various challenges, merits and demerits of ICD inducer nanomedicines were also discussed with shedding light on the future role of this technology in improving the outcomes of cancer immunotherapy.

Advances in Nanomaterials for Immunotherapeutic Improvement of Cancer Chemotherapy

Immuno-stimulative effect of chemotherapy (ISECT) is recognized as a potential alternative to conventional immunotherapies, however, the clinical application is constrained by its inefficiency. Metronomic chemotherapy, though designed to overcome these limitations, offers inconsistent results, with effectiveness varying based on cancer types, stages, and patient-specific factors. In parallel, a wealth of preclinical nanomaterials holds considerable promise for ISECT improvement by modulating the cancer-immunity cycle. In the area of biomedical nanomaterials, current literature reviews mainly concentrate on a specific category of nanomaterials and nanotechnological perspectives, while two essential issues are still lacking, i.e., a comprehensive analysis addressing the causes for ISECT inefficiency and a thorough summary elaborating the nanomaterials for ISECT improvement. This review thus aims to fill these gaps and catalyze further development in this field. For the first time, this review comprehensively discusses the causes of ISECT inefficiency. It then meticulously categorizes six types of nanomaterials for improving ISECT. Subsequently, practical strategies are further proposed for addressing inefficient ISECT, along with a detailed discussion on exemplary nanomedicines. Finally, this review provides insights into the challenges and perspectives for improving chemo-immunotherapy by innovations in nanomaterials.

Chimeric Peptide-Engineered Self-Delivery Nanomedicine for Photodynamic-Triggered Breast Cancer Immunotherapy by Macrophage Polarization

A systemic treatment strategy is urgently demanded to suppress the rapid growth and easy metastasis characteristics of breast cancer. In this work, a chimeric peptide-engineered self-delivery nanomedicine (designated as ChiP-CeR) for photodynamic-triggered breast cancer immunotherapy by macrophage polarization. Among these, ChiP-CeR is composed of the photosensitizer of chlorine e6 (Ce6) and the TLR7/8 agonist of lmiquimod (R837), which is further modified with tumor matrix targeting peptide (Fmoc-K(Fmoc)-PEG8-CREKA. ChiP-CeR is preferred to actively accumulate at the tumor site via specific recognition of fibronectin, which can eradicate primary tumor growth through photodynamic therapy (PDT). Meanwhile, the destruction of primary tumors would trigger immunogenic cell death (ICD) effects to release high-mobility group box-1(HMGB1) and expose calreticulin (CRT). Moreover, ChiP-CeR can also polarize M2-type tumor-associated macrophages (TAMs) into M1-type TAMs, which can activate T cell antitumor immunity in combination with ICD. Overall, ChiP-CeR possesses superior antitumor effects against primary and lung metastatic tumors, which provide an applicable nanomedicine and a feasible strategy for the systemic management of metastatic breast cancer.

Immunogenic cell death-based cancer vaccines: promising prospect in cancer therapy

Tumor immunotherapy is a promising approach for addressing the limitations of conventional tumor treatments, such as chemotherapy and radiotherapy, which often have side effects and fail to prevent recurrence and metastasis. However, the effectiveness and sustainability of immune activation in tumor immunotherapy remain challenging. Tumor immunogenic cell death, characterized by the release of immunogenic substances, damage associated molecular patterns (DAMPs), and tumor associated antigens, from dying tumor cells (DTCs), offers a potential solution. By enhancing the immunogenicity of DTCs through the inclusion of more immunogenic antigens and stimulating factors, immunogenic cell death (ICD) based cancer vaccines can be developed as a powerful tool for immunotherapy. Integrating ICD nanoinducers into conventional treatments like chemotherapy, photodynamic therapy, photothermal therapy, sonodynamic therapy, and radiotherapy presents a novel strategy to enhance treatment efficacy and potentially improve patient outcomes. Preclinical research has identified numerous potential ICD inducers. However, effectively translating these findings into clinically relevant applications remains a critical challenge. This review aims to contribute to this endeavor by providing valuable insights into the in vitro preparation of ICD-based cancer vaccines. We explored established tools for ICD induction, followed by an exploration of personalized ICD induction strategies and vaccine designs. By sharing this knowledge, we hope to stimulate further development and advancement in the field of ICD-based cancer vaccines.

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.

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

The application of nanoparticles-based ferroptosis, pyroptosis and autophagy in cancer immunotherapy

Immune checkpoint blockers (ICBs) have been applied for cancer therapy and achieved great success in the field of cancer immunotherapy. Nevertheless, the broad application of ICBs is limited by the low response rate. To address this issue, increasing studies have found that the induction of immunogenic cell death (ICD) in tumor cells is becoming an emerging therapeutic strategy in cancer treatment, not only straightly killing tumor cells but also enhancing dying cells immunogenicity and activating antitumor immunity. ICD is a generic term representing different cell death modes containing ferroptosis, pyroptosis, autophagy and apoptosis. Traditional chemotherapeutic agents usually inhibit tumor growth based on the apoptotic ICD, but most tumor cells are resistant to the apoptosis. Thus, the induction of non-apoptotic ICD is considered to be a more efficient approach for cancer therapy. In addition, due to the ineffective localization of ICD inducers, various types of nanomaterials have been being developed to achieve targeted delivery of therapeutic agents and improved immunotherapeutic efficiency. In this review, we briefly outline molecular mechanisms of ferroptosis, pyroptosis and autophagy, as well as their reciprocal interactions with antitumor immunity, and then summarize the current progress of ICD-induced nanoparticles based on different strategies and illustrate their applications in the cancer therapy.

Nanocatalysts for modulating antitumor immunity: fabrication, mechanisms and applications

Immunotherapy harnesses the inherent immune system in the body to generate systemic antitumor immunity, offering a promising modality for defending against cancer. However, tumor immunosuppression and evasion seriously restrict the immune response rates in clinical settings. Catalytic nanomedicines can transform tumoral substances/metabolites into therapeutic products in situ, offering unique advantages in antitumor immunotherapy. Through catalytic reactions, both tumor eradication and immune regulation can be simultaneously achieved, favoring the development of systemic antitumor immunity. In recent years, with advancements in catalytic chemistry and nanotechnology, catalytic nanomedicines based on nanozymes, photocatalysts, sonocatalysts, Fenton catalysts, electrocatalysts, piezocatalysts, thermocatalysts and radiocatalysts have been rapidly developed with vast applications in cancer immunotherapy. This review provides an introduction to the fabrication of catalytic nanomedicines with an emphasis on their structures and engineering strategies. Furthermore, the catalytic substrates and state-of-the-art applications of nanocatalysts in cancer immunotherapy have also been outlined and discussed. The relationships between nanostructures and immune regulating performance of catalytic nanomedicines are highlighted to provide a deep understanding of their working mechanisms in the tumor microenvironment. Finally, the challenges and development trends are revealed, aiming to provide new insights for the future development of nanocatalysts in catalytic immunotherapy.

Recent Developments in CaCO3 Nano-Drug Delivery Systems: Advancing Biomedicine in Tumor Diagnosis and Treatment

Calcium carbonate (CaCO3), a natural common inorganic material with good biocompatibility, low toxicity, pH sensitivity, and low cost, has a widespread use in the pharmaceutical and chemical industries. In recent years, an increasing number of CaCO3-based nano-drug delivery systems have been developed. CaCO3 as a drug carrier and the utilization of CaCO3 as an efficient Ca2+ and CO2 donor have played a critical role in tumor diagnosis and treatment and have been explored in increasing depth and breadth. Starting from the CaCO3-based nano-drug delivery system, this paper systematically reviews the preparation of CaCO3 nanoparticles and the mechanisms of CaCO3-based therapeutic effects in the internal and external tumor environments and summarizes the latest advances in the application of CaCO3-based nano-drug delivery systems in tumor therapy. In view of the good biocompatibility and in vivo therapeutic mechanisms, they are expected to become an advancing biomedicine in the field of tumor diagnosis and treatment.

Application of calcium overload-based ion interference therapy in tumor treatment: strategies, outcomes, and prospects

Low selectivity and tumor drug resistance are the main hinderances to conventional radiotherapy and chemotherapy against tumor. Ion interference therapy is an innovative anti-tumor strategy that has been recently reported to induce metabolic disorders and inhibit proliferation of tumor cells by reordering bioactive ions within the tumor cells. Calcium cation (Ca2+) are indispensable for all physiological activities of cells. In particular, calcium overload, characterized by the abnormal intracellular Ca2+ accumulation, causes irreversible cell death. Consequently, calcium overload-based ion interference therapy has the potential to overcome resistance to traditional tumor treatment strategies and holds promise for clinical application. In this review, we 1) Summed up the current strategies employed in this therapy; 2) Described the outcome of tumor cell death resulting from this therapy; 3) Discussed its potential application in synergistic therapy with immunotherapy.

Unlocking the potential of amorphous calcium carbonate: A star ascending in the realm of biomedical application

Calcium-based biomaterials have been intensively studied in the field of drug delivery owing to their excellent biocompatibility and biodegradability. Calcium-based materials can also deliver contrast agents, which can enhance real-time imaging and exert a Ca2+-interfering therapeutic effect. Based on these characteristics, amorphous calcium carbonate (ACC), as a brunch of calcium-based biomaterials, has the potential to become a widely used biomaterial. Highly functional ACC can be either discovered in natural organisms or obtained by chemical synthesis However, the standalone presence of ACC is unstable in vivo. Additives are required to be used as stabilizers or core-shell structures formed by permeable layers or lipids with modified molecules constructed to maintain the stability of ACC until the ACC carrier reaches its destination. ACC has high chemical instability and can produce biocompatible products when exposed to an acidic condition in vivo, such as Ca2+ with an immune-regulating ability and CO2 with an imaging-enhancing ability. Owing to these characteristics, ACC has been studied for self-sacrificing templates of carrier construction, targeted delivery of oncology drugs, immunomodulation, tumor imaging, tissue engineering, and calcium supplementation. Emphasis in this paper has been placed on the origin, structural features, and multiple applications of ACC. Meanwhile, ACC faces many challenges in clinical translation, and long-term basic research is required to overcome these challenges. We hope that this study will contribute to future innovative research on ACC.

NIR-Activatable Heterostructured Nanoadjuvant CoP/NiCoP Executing Lactate Metabolism Interventions for Boosted Photocatalytic Hydrogen Therapy and Photoimmunotherapy

Near-infrared (NIR) laser-induced photoimmunotherapy has aroused great interest due to its intrinsic noninvasiveness and spatiotemporal precision, while immune evasion evoked by lactic acid (LA) accumulation severely limits its clinical outcomes. Although several metabolic interventions have been devoted to ameliorate immunosuppression, intracellular residual LA still remains a potential energy source for oncocyte proliferation. Herein, an immunomodulatory nanoadjuvant based on a yolk-shell CoP/NiCoP (CNCP) heterostructure loaded with the monocarboxylate transporter 4 inhibitor fluvastatin sodium (Flu) is constructed to concurrently relieve immunosuppression and elicit robust antitumor immunity. Under NIR irradiation, CNCP heterojunctions exhibit superior photothermal performance and photocatalytic production of reactive oxygen species and hydrogen. The continuous heat then facilitates Flu release to restrain LA exudation from tumor cells, whereas cumulative LA can be depleted as a hole scavenger to improve photocatalytic efficiency. Subsequently, potentiated photocatalytic therapy can not only initiate systematic immunoreaction, but also provoke severe mitochondrial dysfunction and disrupt the energy supply for heat shock protein synthesis, in turn realizing mild photothermal therapy. Consequently, LA metabolic remodeling endows an intensive cascade treatment with an optimal safety profile to effectually suppress tumor proliferation and metastasis, which offers a new paradigm for the development of metabolism-regulated immunotherapy.

Current Advances in Photodynamic Therapy (PDT) and the Future Potential of PDT-Combinatorial Cancer Therapies

Photodynamic therapy (PDT) is a two-stage treatment that implies the use of light energy, oxygen, and light-activated compounds (photosensitizers) to elicit cancerous and precancerous cell death after light activation (phototoxicity). The biophysical, bioengineering aspects and its combinations with other strategies are highlighted in this review, both conceptually and as they are currently applied clinically. We further explore the recent advancements of PDT with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors as well as the combination of PDT with radiotherapy and immunotherapy as future promising cancer treatments. Finally, we emphasize the potential significance of organoids as physiologically relevant models for PDT.

Long-Acting Nanohybrid Hydrogel Induces Persistent Immunogenic Chemotherapy for Suppressing Postoperative Tumor Recurrence and Metastasis

Despite the continuous advancement of surgical resection techniques, postoperative tumor recurrence and metastasis remain a huge challenge. Here, we constructed an injectable curcumin/doxorubicin-loaded nanoparticle (NanoCD) hydrogel, which could effectively inhibit tumor regrowth and metastasis via reshaping the tumor immune microenvironment (TIME) for highly effective postsurgical cancer treatment. NanoCD was prepared by the controlled assembly of curcumin (CUR) and doxorubicin (DOX) via π-π stacking and hydrogen bonding in the presence of human serum albumin. To facilitate prolonged treatment of postsurgical tumors, NanoCD was further incorporated into the temperature-sensitive Poloxamer 407 gel (NanoCD@Gel) for intracavity administration. Mechanistically, DOX induced the generation of intracellular reactive oxygen species (ROS) and CUR reduced the ROS metabolism by inhibiting thioredoxin reductase (TrxR). The synergy of DOX and CUR amplified intracellular ROS levels and thus resulted in enhanced immunogenic cell death (ICD) of tumor cells. Upon being injected into the tumor cavity after resection, the in situ-generated NanoCD@Gel allowed the local release of CUR and DOX in a controlled manner to induce local chemotherapy and persistently activate the antitumor immune response, thereby achieving enhanced immunogenic chemotherapy with reduced systemic toxicity. Our work provides an elegant strategy for persistently stimulating effective antitumor immunity to prevent postsurgical tumor recurrence and metastasis.

Boosting immunogenic cell death via hollow MnO2-based multiple stimuli-responsive drug delivery systems for improved cancer immunotherapy

Cancer treatment by inducing tumor cell immunogenic cell death (ICD) is critical for tumor therapy. However, ICD activation by single pathway is often limited in practical application due to its low efficiency. In addition, the low pH and anoxic microenvironments in solid tumors greatly limit the effective activation of ICD. Herein, hollow manganese dioxide (H-MnO2) nanomaterials were selected to load both Mitoxantrone (MTZ) and Chlorin e6 (Ce6) due to its hollow structure and ability to release drugs in the acidic environments. Thus, the synergy of photodynamic therapy (PDT), photothermal therapy (PTT) and chemotherapy can induce the process of immunogenic cell death, stimulate the maturation of dendritic cells (DCs), and activate the immune response to kill tumor cells dramatically. Efficient immunotherapeutic effects were obtained when MnO2-C/M-HA was given intravenously to 4T1 tumor-bearing BALB/c mice with 660 nm near-infrared laser irradiation. This study overcame the limitations of monotherapy and provided a multifunctional platform for tumor immunotherapy.

Aspect ratio-dependent dual-regulation of the tumor immune microenvironment against osteosarcoma by hydroxyapatite nanoparticles

Accumulating studies demonstrated that hydroxyapatite nanoparticles (HANPs) showed a selective anti-tumor effect, making them a good candidate for osteosarcoma (OS) treatment. However, the capacity of HANPs with different aspect ratios to regulate tumor immune microenvironment (TIM) was scarcely reported before. To explore it, the three HANPs with aspect ratios from 1.86 to 6.25 were prepared by wet chemical method. After a 24 or 72 h-exposure of OS UMR106 cells or macrophages to the nanoparticles, the tumor cells exhibited immunogenic cell death (ICD) indicated by the increased production of calreticulin (CRT), adenosine triphosphate (ATP) and high mobility group box 1 (HMGB1), and macrophages were activated with the release of pro-inflammatory cytokines. Next, the beneficial crosstalk between tumor cells and macrophages generated in the presence of HANPs for improved anti-tumor immunity activation. In the OS-bearing cognate rat model, HANPs inhibited OS growth, which was positively correlated with CRT and HMGB1 expression, and macrophage polarization in the tumor tissues. Additionally, HANPs promoted CD8+ T cell infiltration into the tumor and systemic dendritic cell maturation. Particularly, HANPs bearing the highest aspect ratio exhibited the strongest immunomodulatory and anti-tumor function. This study suggested the potential of HANPs to be a safe and effective drug-free nanomaterial to control the TIM for OS therapy. STATEMENT OF SIGNIFICANCE: Emerging studies demonstrated that hydroxyapatite nanoparticles (HANPs) inhibited tumor cell proliferation and tumor growth. However, the underlying anti-tumor mechanism still remains unclear, and the capacity of HANPs without any other additive to regulate tumor immune microenvironment (TIM) was scarcely reported before. Herein, we demonstrated that HANPs, in an aspect ratio-dependent manner, showed the potential to delay the growth of osteosarcoma (OS) and to regulate TIM by promoting the invasion of CD8+ T cells and F4/80+ macrophages, and inducing immunogenic cell death (ICD) in tumors. This work revealed the new molecular mechanism for HANPs against OS, and suggested HANPs might be a novel ICD inducer for OS treatment.

Prodrug-loaded semiconducting polymer hydrogels for deep-tissue sono-immunotherapy of orthotopic glioblastoma

Although immunotherapy has achieved great success in the treatment of a variety of tumors, its efficacy for glioblastoma (GBM) is still limited. Both the immunosuppressive tumor microenvironment (TME) and poor penetration of immunotherapeutic agents into tumors contributed to the poor anti-glioma immunity. Herein, we develop an injectable prodrug-loaded hydrogel delivery system with sono-activatable properties for sonodynamic therapy (SDT)-triggered immunomodulation for GBM treatment. The prodrug alginate hydrogels (APN), which contain semiconducting polymer nanoparticles (SPNs) and the NLG919 prodrug linked by singlet oxygen (1O2)-cleavable linkers, are in situ formed via coordination of alginate solution with Ca2+ in the TME. SPNs serve as sonosensitizers to produce 1O2 upon ultrasound (US) irradiation for SDT. The generated 1O2 not only induce immunogenic cell death, but also break 1O2-cleavable linkers to precisely activate the NLG919 prodrug. Antitumor immunity is significantly amplified due to the reversal of immunosuppression mediated by indolamine 2,3-dioxygenase-dependent tryptophan metabolism. This smart prodrug hydrogel platform potently inhibits tumor growth in orthotopic glioma-bearing mice. Collectively, this work provides a sono-activatable hydrogel platform for precise sono-immunotherapy against GBM.

Recent progress of metal-based nanomaterials with anti-tumor biological effects for enhanced cancer therapy

Metal-based nanomaterials have attracted broad attention recently due to their unique biological physical and chemical properties after entering tumor cells, namely biological effects. In particular, the abilities of Ca2+ to modulate T cell receptors activation, K+ to regulate stem cell differentiation, Mn2+ to activate the STING pathway, and Fe2+/3+ to induce tumor ferroptosis and enhance catalytic therapy, make the metal ions and metal-based nanomaterials play crucial roles in the cancer treatments. Therefore, due to the superior advantages of metal-based nanomaterials and the characteristics of the tumor microenvironment, we will summarize the recent progress of the anti-tumor biological effects of metal-based nanomaterials. Based on the different effects of metal-based nanomaterials on tumor cells, this review mainly focuses on the following five aspects: (1) metal-enhanced radiotherapy sensitization, (2) metal-enhanced catalytic therapy, (3) metal-enhanced ferroptosis, (4) metal-enhanced pyroptosis, and (5) metal-enhanced immunotherapy. At the same time, the shortcomings of the biological effects of metal-based nanomaterials on tumor therapy are also discussed, and the future research directions have been prospected. The highlights of promising biosafety, potent efficacy on biological effects for tumor therapy, and the in-depth various biological effects mechanism studies of metal-based nanomaterials provide novel ideas for the future biological application of the nanomaterials.

Promotion of ICD via Nanotechnology

Immunotherapy represents the most promising treatment strategy for cancer, but suffers from compromised therapeutic efficiency due to low immune activity of tumor cells and an immunosuppressive microenvironment, which significantly hampers the clinical translations of this treatment strategy. To promote immunotherapy with desired therapeutic efficiency, immunogenic cell death (ICD), a particular type of death capable of reshaping body's antitumor immune activity, has drawn considerable attention due to the potential to stimulate a potent immune response. Still, the potential of ICD effect remains unsatisfactory because of the intricate tumor microenvironment and multiple drawbacks of the used inducing agents. ICD has been thoroughly reviewed so far with a general classification of ICD as a kind of immunotherapy strategy and repeated discussion of the related mechanism. However, there are no published reviews, to the authors' knowledge, providing a systematic summarization on the enhancement of ICD via nanotechnology. For this purpose, this review first discusses the four stages of ICD according to the development mechanisms, followed by a comprehensive description on the use of nanotechnology to enhance ICD in the corresponding four stages. The challenges of ICD inducers and possible solutions are finally summarized for future ICD-based enhanced immunotherapy.

Local Drug Delivery Techniques for Triggering Immunogenic Cell Death

Immunogenic cell death (ICD), a dying state of the cells, encompasses the changes in the conformations of cell surface and the release of damage-associated molecular patterns, which could initiate an adaptive immune response by stimulating the dendritic cells to present antigens to T cells. Advancements in biomaterials, nanomedicine, and micro- and nano-technologies have facilitated the development of effective ICD inducers, but the potential toxicity of these vesicles encountered in drug delivery via intravenous administration hampers their further application. As alternatives, the local drug delivery systems have gained emerging attention due to their ability to prolong the retention of high payloads at the lesions, sequester drugs from harsh environments, overcome biological barriers to exert optimal efficacy, and minimize potential side effects to guarantee bio-safety. Herein, a brief overview of the local drug delivery techniques used for ICD inducers is provided, explaining how these techniques broaden, alter, and enhance the therapeutic capability while circumventing systemic toxicity at the same time. The historical context and prominent examples of the local administration of ICD inducers are introduced. The complexities, potential pitfalls, and opportunities for local drug delivery techniques in cancer immunotherapy are also discussed.

Usnea Acid-Incorporated Ca2+ /Mn2+ Ions Reservoirs for Elevated Ion-Interference Therapy through Synergetic Biocatalysis and Osmolarity Imbalance

Ion-interference therapy (IIT) utilizes ions to disturb intracellular biological processes and has been received increasing attention in tumor treatments recently. However, the low therapeutic efficiency still hinders its further biological applications. Herein, via a simple and one-pot gas diffusion process, polyethylene glycol (PEG)-modified Mn2+ ions and usnic acid (UA)-incorporated CaCO3 nanomaterials (PEG CaMnUA) as Ca2+ /Mn2+ ions reservoirs are prepared for magnetic resonance imaging (MRI)-guided UA-elevated IIT. Among PEG CaMnUA, UA not only increases cytoplasmic Ca2+ ions to amplify Ca2+ overload caused by CaCO3 decomposition, but also enhances Mn2+ ions-participated Fenton-like biocatalysis by intracellular H2 O2 generation and glutathione consumption. Then increasing the intracellular oxidative stress and decreasing the triphosadenine supply induce apoptosis together, resulting in UA-boosted IIT. The simple and efficient design of the dual ions reservoirs will contribute to improve the antitumor activity of IIT and further development of calcium-based nanomaterials in the future.

Mesoporous silica/organosilica nanoparticles for cancer immunotherapy

Cancer is one of the fatal diseases in the history of humankind. In this regard, cancer immunotherapeutic strategies have revolutionized the traditional mode of cancer treatment. Silica based nano-platforms have been extensively applied in nanomedicine including cancer immunotherapy. Mesoporous silica nanoparticles (MSN) and mesoporous organosilica nanoparticles (MON) are attractive candidates due to the ease in controlling the structural parameters as needed for the targeted immunotherapeutic applications. Especially, the MON provide an additional advantage of controlling the composition and modulating the biological functions to actively synergize with other immunotherapeutic strategies. In this review, the applications of MSN, MON, and metal-doped MSN/MON in the field of cancer immunotherapy and tumor microenvironment regulation are comprehensively summarized by highlighting the structural and compositional attributes of the silica-based nanoplatforms.

Tailor-Made Autophagy Cascade Amplification Polymeric Nanoparticles for Enhanced Tumor Immunotherapy

Chemotherapeutics can induce immunogenic cell death (ICD) by triggering autophagy and mediate antitumor immunotherapy. However, using chemotherapeutics alone can only cause mild cell-protective autophagy and be incapable of inducing sufficient ICD efficacy. The participation of autophagy inducer is competent to enhance autophagy, so the level of ICD is promoted and the effect of antitumor immunotherapy is highly increased. Herein, tailor-made autophagy cascade amplification polymeric nanoparticles STF@AHPPE are constructed to enhance tumor immunotherapy. Arginine (Arg), polyethyleneglycol-polycaprolactone, and epirubicin (EPI) are grafted onto hyaluronic acid (HA) via disulfide bond to form the AHPPE nanoparticles and autophagy inducer STF-62247 (STF) is loaded. When STF@AHPPE nanoparticles target to tumor tissues and efficiently enter into tumor cells with the help of HA and Arg, the high glutathione concentration leads to the cleavage of disulfide bond and the release of EPI and STF. Finally, STF@AHPPE induces violent cytotoxic autophagy and strong ICD efficacy. As compared to AHPPE nanoparticles, STF@AHPPE nanoparticles kill the most tumor cells and show the more obvious ICD efficacy and immune activation ability. This work provides a novel strategy for combining tumor chemo-immunotherapy with autophagy induction.

Biomaterials That Induce Immunogenic Cell Death

The immune system takes part in most physiological and pathological processes of the body, including the occurrence and development of cancer. Immunotherapy provides a promising modality for inhibition and even the cure of cancer. During immunotherapy, the immunogenic cell death (ICD) of tumor cells induced by chemotherapy, radiotherapy, phototherapy, bioactive materials, and so forth, triggers a series of cellular responses by causing the release of tumor-associated antigens and damage-associated molecular patterns, which ultimately activate innate and adaptive immune responses. Among them, the ICD-induced biomaterials attract increasing conditions as a benefit of biosafety and multifunctional modifications. This Review summarizes the research progress in biomaterials for inducing ICD via triggering endoplasmic reticulum oxidative stress, mitochondrial dysfunction, and cell membrane rupture and discusses the application prospects of ICD-inducing biomaterials in clinical practice for cancer immunotherapy.

Curdione ameliorates sepsis-induced lung injury by inhibiting platelet-mediated neutrophil extracellular trap formation

Sepsis-associated acute lung injury remains to be a major cause of morbidity and mortality worldwide, and there is a lack of effective therapeutic drugs. Curdione, an activeingredient of Curcuma zedoary, a traditional Chinese medicine (TCM), possesses a variety of pharmacological actions, such as anti-inflammatory, antioxidant and inhibition of platelet aggregation. However, whether curdione protects against sepsis-induced lung injury is still undetermined. In this study, we investigated the effects of curdione on sepsis-induced lung injury. Cecal ligation and puncture (CLP) surgery was performed in mice to establish a model of sepsis. Twenty-four hours after CLP, bronchoalveolar lavage fluid (BALF) and lung tissue samples were harvested for investigation. The protective effects of curdione on acute lung injury and potential mechanisms were explored by detecting pathological sections, exudative proteins, oxidative responses, inflammatory factors, platelet activation, neutrophil infiltration, and neutrophil extracellular trap (NET) formation in the lung and were further verified in vitro. We showed that treatment with curdione clearly relieved histopathological changes, reduced inflammatory cytokine elevation and total protein concentrations in BALF, and decreased oxidative stress responses in lung tissues. In addition, curdione inhibited platelet activation, further blocking the interaction between platelets and neutrophils. Finally, neutrophil infiltration and NET formation was also reduced in mice treated with curdione. In conclusion, curdione alleviates sepsis-induced lung injury by inhibiting platelet-mediated neutrophil recruitment, infiltration, and NET formation as well as its anti-inflammatory and antioxidant properties. Curdione has great therapeutic potential in sepsis.

Multifunctional Nano-Biomaterials for Cancer Therapy via Inducing Enhanced Immunogenic Cell Death

Immunotherapy is considered to be one of the most promising methods to overcome cancer. Immunogenic cell death (ICD), as a special form of cell death that can trigger an antitumor immune response, has attracted increasing attention for cancer immunotherapy. Presently, ICD-mediating immunotherapy needs to overcome many hurdles including a lack of targeted delivery systems for ICD inducers, insufficient antitumor immunity, and the immunosuppressive tumor microenvironment. Recent research has demonstrated that nano-biomaterials exhibit unique biochemphysical properties at the nanoscale, providing a prospective approach to overcoming these obstacles. In this review, the authors first survey the occurrence, processes, and detection methods of ICD. Subsequently, the recent advances of nano-biomaterials applied to enhance ICD according to the key steps in the process of ICD, particularly with a focus on the mechanisms and lifting schemes are investigated. Finally, based on the achievement in the representative studies, the prospects and challenges of nanotechnology in ICD for cancer therapy are discussed to enable clinical translation.

Cancer Immunotherapy Elicited by Immunogenic Cell Death Based on Smart Nanomaterials

Cancer immunotherapy has been a revolutionary cancer treatment modality because it can not only eliminate primary tumors but also prevent metastases and recurrent tumors. Immunogenic cell death (ICD) induced by various treatment modalities, including chemotherapy, phototherapy, and radiotherapy, converts dead cancer cells into therapeutic vaccines, eliciting a systemic antigen-specific antitumor. However, the outcome effect of cancer immunotherapy induced by ICD has been limited due to the low accumulation efficiency of ICD inducers in the tumor site and concomitant damage to normal tissues. The boom in smart nanomaterials is conducive to overcoming these hurdles owing to their virtues of good stability, targeted lesion site, high bioavailability, on-demand release, and good biocompatibility. Herein, the design of targeted nanomaterials, various ICD inducers, and the applications of nanomaterials responsive to different stimuli, including pH, enzymes, reactive oxygen species, or dual responses are summarized. Furthermore, the prospect and challenges are briefly outlined to provide reference and inspiration for designing novel smart nanomaterials for immunotherapy induced by ICD.

Self-immolative polymer-based immunogenic cell death inducer for regulation of redox homeostasis

Doxorubicin (DOX), widely used as an anticancer drug, is considered an immunogenic cell death (ICD) inducer that enhances cancer immunotherapy. However, its extended application as an ICD inducer has been limited owing to poor antigenicity and inefficient adjuvanticity. To enhance the immunogenicity of DOX, we prepare a reactive oxygen species (ROS)-responsive self-immolative polymer (R-SIP) that can efficiently destroy redox homeostasis via self-immolation-mediated glutathione depletion in cancer cells. Owing to its amphiphilic nature, R-SIP self-assemble into nano-sized particles under aqueous conditions, and DOX is efficiently encapsulated inside the nanoparticles by a simple dialysis method. Interestingly, when treated with 4T1 cancer cells, DOX-encapsulated R-SIP (DR-SIP) induces the phosphorylation of eukaryotic translation initiation factor 2α and overexpression of ecto-calreticulin, resulting in endoplasmic reticulum-associated ICD. In addition, DR-SIP contributes to the maturation of dendritic cells by promoting the release of damage-associated molecular patterns (DAMPs) from cancer cells. When intravenously administered to tumor-bearing mice, DR-SIP remarkably inhibits tumor growth compared with DOX alone. Overall, DR-SIP may have the potential to elicit an immune response as an ICD inducer.

Immuno-photodynamic Therapy (IPDT): Organic Photosensitizers and Their Application in Cancer Ablation

Photosensitizer-based photodynamic therapy (PDT) has been considered as a promising modality for fighting diverse types of cancers. PDT directly inhibits local tumors by a minimally invasive strategy, but it seems to be incapable of achieving complete eradication and fails to prevent metastasis and recurrence. Recently, increasing events proved that PDT was associated with immunotherapy by triggering immunogenic cell death (ICD). Upon a specific wavelength of light irradiation, the photosensitizers will turn the surrounding oxygen molecules into cytotoxic reactive oxygen species (ROS) for killing the cancer cells. Simultaneously, the dying tumor cells release tumor-associated antigens, which could improve immunogenicity to activate immune cells. However, the progressively enhanced immunity is typically limited by the intrinsic immunosuppressive tumor microenvironment (TME). To overcome this obstacle, immuno-photodynamic therapy (IPDT) has come to be one of the most beneficial strategies, which takes advantage of PDT to stimulate the immune response and unite immunotherapy for inducing immune-OFF tumors to immune-ON ones, to achieve systemic immune response and prevent cancer recurrence. In this Perspective, we provide a review of recent advances in organic photosensitizer-based IPDT. The general process of immune responses triggered by photosensitizers (PSs) and how to enhance the antitumor immune pathway by modifying the chemical structure or conjugating with a targeting component was discussed. In addition, future perspectives and challenges associated with IPDT strategies are also discussed. We hope this Perspective could inspire more innovative ideas and provide executable strategies for future developments in the war against cancer.

Heterostructural Nanoadjuvant CuSe/CoSe2 for Potentiating Ferroptosis and Photoimmunotherapy through Intratumoral Blocked Lactate Efflux

The desirable curative effect in clinical immunotherapy has been challenging due to the immunosuppressive tumor microenvironment (TME) with high lactic acid (LA) metabolism in solid tumors. Although targeting metabolic reprogramming of tumor cells can restore the survival and function of immune cells in the TME, it is also plagued by insufficient immunogenicity. Herein, an activatable immunomodulatory nanoadjuvant CuSe/CoSe₂@syrosingopine (CSC@Syro) is constructed for simultaneously relieving immunosuppressive TME and boosting tumor immune response. Specifically, CuSe/CoSe₂ (CSC) exhibits TME-activated glutathione (GSH) depletion and hydroxyl radical (^•OH) generation for potential ferroptosis. Meanwhile, the remarkable photothermal conversion efficiency and elevated photocatalytic ROS level both promote CSC heterostructures to induce robust immunogenic cell death (ICD). Besides, the loaded syrosingopine inhibitor achieves LA metabolism blockade in cancer cells by downregulating the expression of monocarboxylate transporter 4 (MCT4), which could sensitize ferroptosis by intracellular milieu acidification and neutralize the acidic TME to alleviate immunosuppression. Hence, advanced metabolic modulation confers the potentiated immune infiltration of ICD-stimulated T lymphocytes and further reinforces antitumor therapy. In brief, CSC@Syro-mediated synergistic therapy could elicit potent immunogenicity and suppress tumor proliferation and metastasis effectually by integrating the tumor metabolic regulation and ferroptosis with immunotherapy.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

Nanodrug constructed using dietary antioxidants for immunotherapy of metastatic tumors

Immunogenic cell death (ICD) induced by reactive oxygen species (ROS) represents a particular form of tumor cell death for approaching the problem of low immunogenicity of tumors in immunotherapy, while the oxidative damage to normal cells of current ICD inducers hinders their clinical application. Herein, a new ICD inducer VC@cLAV constructed solely by dietary antioxidants, lipoic acid (LA) and vitamin C (VC), is developed, which could promote heavy intracellular ROS production in cancer cells for ICD induction while acting as an anti-oxidant in non-cancer cells for cytoprotection, and thus hold high biosafety. In vitro studies show that VC@cLAV induced a release of antigens and a maturation rate of DCs up to 56.5%, approaching the positive control (58.4%). In vivo combined with αPD-1, VC@cLAV showed excellent antitumor activity against both primary and distant metastatic tumors with an inhibition rate of 84.8% and 79.0% compared to 14.2% and 10.0% in the αPD-1 alone group. Notably, VC@cLAV established a long-term antitumor immune memory effect against tumor rechallenging. This study not only presents a new kind of ICD inducer but also provides an impetus for the development of dietary antioxidant-based cancer drugs.

Boosting Checkpoint Immunotherapy with Biomaterials

The immune checkpoint blockade (ICB) therapy has revolutionized the field of cancer treatment, while low response rates and systemic toxicity limit its clinical outcomes. With the rapid advances in nanotechnology and materials science, various types of biomaterials have been developed to maximize therapeutic efficacy while minimizing side effects by increasing tumor antigenicity, reversing immunosuppressive microenvironment, amplifying antitumor immune response, and reducing extratumoral distribution of checkpoint inhibitors as well as enhancing their retention within target sites. In this review, we reviewed current design strategies for different types of biomaterials to augment ICB therapy effectively and then discussed present representative biomaterial-assisted immune modulation and targeted delivery of checkpoint inhibitors to boost ICB therapy. Current challenges and future development prospects for expanding the ICB with biomaterials were also summarized. We anticipate this review will be helpful for developing emerging biomaterials for ICB therapy and promoting the clinical application of ICB therapy.

Hybrid Nanomaterials for Cancer Immunotherapy

Nano-immunotherapy has been recognized as a highly promising strategy for cancer treatment in recent decades, which combines nanotechnology and immunotherapy to combat against tumors. Hybrid nanomaterials consisting of at least two constituents with distinct compositions and properties, usually organic and inorganic, have been engineered with integrated functions and enormous potential in boosting cancer immunotherapy. This review provides a summary of hybrid nanomaterials reported for cancer immunotherapy, including nanoscale metal-organic frameworks, metal-phenolic networks, mesoporous organosilica nanoparticles, metallofullerene nanomaterials, polymer-lipid, and biomacromolecule-based hybrid nanomaterials. The combination of immunotherapy with chemotherapy, chemodynamic therapy, radiotherapy, radiodynamic therapy, photothermal therapy, photodynamic therapy, and sonodynamic therapy based on hybrid nanomaterials is also discussed. Finally, the current challenges and the prospects for designing hybrid nanomaterials and their application in cancer immunotherapy are outlined.

A Phase-Change Mediated Intelligent Nanoplatform for Chemo/Photothermal/Photodynamic Therapy of Cancer

Up to now, chemotherapy is still the main strategy for cancer treatment. However, the emergence of chemo-resistance and systemic side effects often seriously affects the treatment and prognosis. Herein, an intelligent nanoplatform based on dendritic mesoporous organosilica nanoparticles (DMON) is constructed. The encapsulated phase-change material, 1-tetradecanol (TD) can serve as a "doorkeeper" and enable the responsive release of drugs based on the temperature changes. Meanwhile, polyethylene glycol (PEG) is used to improve the dispersibility and biocompatibility. Cisplatin is chosen as the model of chemotherapy drug, which is co-loaded with indocyanine green (ICG) in DMON to produce DMON-PEG-cisplatin/ICG-TD (DPCIT). Exciting, the hyperthermia and reactive oxygen species induced by ICG under the NIR-laser irradiation will initiate a phase transition of TD to release cisplatin, thus leading a combined therapy (chemo/photothermal/photodynamic therapy). The results indicated that under laser irradiation, DPCIT can kill cancer cells and inhibit tumor growth efficiently. In addition, the designed nanoplatform reveals minimal systemic toxicity in vivo, in contrast, the distinct liver damage can be observed by the direct treatment of cisplatin. Overall, this research may provide a general approach for the targeted delivery and controlled release of chemotherapy drugs to realize a cooperatively enhanced multimodal tumor therapy.

Enhanced Immunotherapy Based on Combining the Pro-phagocytosis and Anti-phagocytosis Checkpoint Blockade for Tumor Eradication

Compared to the activation of acquired immunity by the immune checkpoint blockade, the activation of innate immunity via anti-phagocytosis checkpoint blockade could significantly increase the beneficiary population of immunotherapy. However, the activation of innate immunity and the occurrence of phagocytosis are only accomplished when the interaction between pro-phagocytosis signals and anti-phagocytosis signals is realized. Herein, a versatile nanoplatform (DHMR) based on mesoporous silicon nanoparticles (MSNPs) has been constructed. Two drugs, doxorubicin, a chemotherapeutic drug which could initiate tumor cells to release pro-phagocytosis signals, and RRx-001, an immunoadjuvant that could effectively implement the anti-phagocytosis checkpoint blockade, were loaded in MSNPs. Further decoration of hyaluronic acid encapsulation endows DHMR with the function of tumor targeting and long circulation. Ultimately, the DHMR system could efficiently and accurately target tumor tissue, release the drugs in the tumor microenvironment, achieve the activation of innate immunity, and finally dramatically inhibit the growth and metastasis of tumor cells.

Evoking tumor associated macrophages by mitochondria-targeted magnetothermal immunogenic cell death for cancer immunotherapy

Immunogenic cell death (ICD) based on endoplasmic reticulum (ER) stress has been widely studied as the fundamentals of cancer immunotherapy. However, the currently available ICD inducers are still very rare and mostly highly toxic chemotherapeutic drugs. Herein, a novel ICD modality based on mitochondrial heat stress by magnetic hyperthermia treatment (MHT), is proposed for effectively evoking tumor-associated macrophages (TAMs) against cancer cells. A monodisperse and biocompatible nanomedicine by grafting arginyl-glycyl-aspartic acid (RGD) and (3-carboxypropyl)triphenylphosphonium bromide (TPP) onto the surface of superparamagnetic ZnCoFe₂O₄@ZnMnFe₂O₄ nanoparticles (MNPs), named as MNPs-RGD-TPP (MRT), was synthesized for mitochondrial heat stress-induced oxidative damage of tumor cells under the magnetothermal manipulation. Such heat stress-damaged mitochondria can cause the immunogenic death of tumor cells to release damage-associated molecular patterns (DAMPs), including ATP and HSP 70, to M1-polarize TAMs, resulting in the reactivated immunoresponse of macrophages against cancer cells. The effectiveness and robustness of MRT nanomedicine in evoking TAMs-mediated extracellular killing or phagocytosis are verified both in vitro and in vivo. Such a therapeutic approach based on mitochondria-targeted magnetothermal ICD for activating TAMs may be instructive to future anticancer immunotherapy.

Biodegradable Ca2+ Nanomodulators Activate Pyroptosis through Mitochondrial Ca2+ Overload for Cancer Immunotherapy

Pyroptosis provides a new direction and broad prospects for cancer immunotherapy. However, the development of a nanoplatform as a pyroptosis inducer is limited, and the discovery of a new type of nano-pyroptosis inducer for cancer immunotherapy is still imminent. Herein, biodegradable Ca²⁺ nanomodulators (CaNMs) are prepared as pyroptosis inducers for cancer immunotherapy via mitochondrial Ca²⁺ overload. The obtained CaNMs can decompose under low pH to release Ca²⁺ and curcumin, leading to a sudden surge in mitochondrial Ca²⁺ ions, eventually resulting in pyroptosis. We not only confirm the occurrence of mitochondrial Ca²⁺ overload-triggered pyroptosis for the first time but also reveal the robust immune responses via CaNMs, along with remarkably suppressing tumor proliferation and lung metastasis. This work will provide new strategies and inspiration for pyroptosis-mediated cancer treatments, greatly contributing to the further development of Ca²⁺ nanomodulators.

A Selective Reduction of Osteosarcoma by Mitochondrial Apoptosis Using Hydroxyapatite Nanoparticles

Background

In recent years, using hydroxyapatite nanoparticles (HANPs) for tumor therapy attracted increasing attention because HANPs were found to selectively suppress the growth of tumor cells but exhibit ignorable toxicity to normal cells.

Purpose

This study aimed to investigate the capacities of HANPs with different morphologies and particle sizes against two kinds of osteosarcoma (OS) cells, human OS 143B cells and rat OS UMR106 cells.

Methods

Six kinds of HANPs with different morphologies and particle sizes were prepared by wet chemical method. Then, the antitumor effect of these nanoparticles was characterized by means of in vitro cell experiments and in vivo tumor-bearing mice model. The underlying antitumor mechanism involving mitochondrial apoptosis was also investigated by analysis of intracellular calcium, expression of apoptosis-related genes, reactive oxygen species (ROS), and the endocytosis efficiency of the particles in tumor cells.

Results

Both in vitro cell experiments and in vivo mice model evaluation revealed the anti-OS performance of HANPs depended on the concentration, morphology, and particle size of the nanoparticles, as well as the OS cell lines. Among the six HANPs, rod-like HANPs (R-HANPs) showed the best inhibitory activity on 143B cells, while needle-like HANPs (N-HANPs) inhibited the growth of UMR106 cells most efficiently. We further demonstrated that HANPs induced mitochondrial apoptosis by selectively raising intracellular Ca²⁺ and the gene expression levels of mitochondrial apoptosis-related molecules, and depolarizing mitochondrial membrane potential in tumor cells but not in MC3T3-E1, a mouse pre-osteoblast line. Additionally, the anti-OS activity of HANPs also linked with the endocytosis efficiency of the particles in the tumor cells, and their ability to drive oxidative damage and immunogenic cell death (ICD).

Conclusion

The current study provides an effective strategy for OS therapy where the effectiveness was associated with the particle morphology and cell line.

Connecting Calcium-Based Nanomaterials and Cancer: From Diagnosis to Therapy

As the indispensable second cellular messenger, calcium signaling is involved in the regulation of almost all physiological processes by activating specific target proteins. The importance of calcium ions (Ca²⁺) makes its "Janus nature" strictly regulated by its concentration. Abnormal regulation of calcium signals may cause some diseases; however, artificial regulation of calcium homeostasis in local lesions may also play a therapeutic role. "Calcium overload," for example, is characterized by excessive enrichment of intracellular Ca²⁺, which irreversibly switches calcium signaling from "positive regulation" to "reverse destruction," leading to cell death. However, this undesirable death could be defined as "calcicoptosis" to offer a novel approach for cancer treatment. Indeed, Ca²⁺ is involved in various cancer diagnostic and therapeutic events, including calcium overload-induced calcium homeostasis disorder, calcium channels dysregulation, mitochondrial dysfunction, calcium-associated immunoregulation, cell/vascular/tumor calcification, and calcification-mediated CT imaging. In parallel, the development of multifunctional calcium-based nanomaterials (e.g., calcium phosphate, calcium carbonate, calcium peroxide, and hydroxyapatite) is becoming abundantly available. This review will highlight the latest insights of the calcium-based nanomaterials, explain their application, and provide novel perspective. Identifying and characterizing new patterns of calcium-dependent signaling and exploiting the disease element linkage offer additional translational opportunities for cancer theranostics.

Host-guest interaction-based supramolecular prodrug self-assemblies for GSH-consumption augmented chemotherapy

The over-expressed cellular glutathione (GSH) severely restricts the chemotherapeutic efficacy due to the GSH-induced detoxification of chemical drugs. Herein, how to construct effective drug delivery systems with GSH-consumption property is still a general concern and a major challenge. In this study, the host-guest interactions between water-soluble pillar[6]arene (WP[6]) and chlorambucil-arylboronic acid (Cb-BA) were utilized to construct supramolecular prodrug self-assemblies (SPSAs) with specific stimuli-responsive property. Notably, the BA moiety could not only consume GSH but also rapidly bind curcumin (Cur), which could inhibit the thioredoxin reductase (TrxR) to further reduce the GSH biosynthesis pathway. Benefiting from the functionality of BA-Cur conjugates, the GSH levels could be significantly downregulated, paving a novel way to enhance chemotherapeutic efficacy. In vitro and in vivo investigations demonstrated that this two-pronged GSH-depletion strategy could amplify the cellular oxidative stress and achieve excellent anti-tumor efficacy.

In Situ Tumor Vaccination with Calcium-Linked Degradable Coacervate Nanocomplex Co-Delivering Photosensitizer and TLR7/8 Agonist to Trigger Effective Anti-Tumor Immune Responses

In situ anti-tumor vaccination is an attractive type of cancer immunotherapy which relies on the effectiveness of dendritic cells (DCs) to engulf tumor antigens, become activated, and present antigens to T cells in lymphoid tissue. Here, a multifunctional nanocomplex based on calcium crosslinked polyaspartic acid conjugated to either a toll-like receptor (TLR)7/8 agonist or a photosensitizer is reported. Intratumoral administration of the nanocomplex followed by laser irradiation induces cell killing and hence generation of a pool of tumor-associated antigens, with concomitant promotion of DCs maturation and expansion of T cells in tumor-draining lymph nodes. Suppression of tumor growth is observed both at the primary site and at the distal site, thereby hinting at successful induction of an adaptive anti-tumor response. This strategy holds promise for therapeutic application in a pre-operative and post-operative setting to leverage to mutanome of the patient's own tumor to mount immunological memory to clear residual tumor cells and metastasis.

Non-cytotoxic Nanoparticles Re-educating Macrophages Achieving both Innate and Adaptive Immune Responses for Tumor Therapy

Macrophages are important antigen-presenting cells to combat tumor via both innate and adaptive immunity, while they are programmed to M2 phenotype in established tumors and instead promote cancer development and metastasis. Here, we develop a nanomedicine that can re-educate M2 polarized macrophages to restore their anti-tumor activities. The nanomedicine has a core-shell structure to co-load IPI549, a PI3Kγ inhibitor, and CpG, a Toll-like receptor 9 agonist. Specifically, the hydrophobic IPI549 is self-assembled into a pure drug nano-core, while MOF shell layer is coated for CpG encapsulation, achieving extra-high total drugs loading of 44%. Such nanosystem could facilitate intracellular delivery of the payloads but without any cytotoxicity, displaying excellent biocompatibility. After entering macrophages, the released IPI549 and CpG exert a synergistic effect to switch macrophages from M2 to M1 phenotype, which enables anti-tumor activities via directly engulfing tumor cells or excreting tumor killing cytokines. Moreover, tumor antigens released from the dying tumor cells could be effectively presented by the re-educated macrophages owing to the up-regulation of various antigen presenting mediators, resulting in infiltration and activation of cytotoxic T lymphocytes. As a result, the nanosystem triggers a robust anti-tumor immune response in combination with PD-L1 antibody to inhibit tumor growth and metastasis. This work provides a non-cytotoxic nanomedicine to modulate tumor immune microenvironment by reprograming macrophages.