Activatable Polymer Nanoenzymes for Photodynamic Immunometabolic Cancer Therapy

Energy-storing DNA-based hydrogel remodels tumor microenvironments for laser-free photodynamic immunotherapy

Photodynamic therapy (PDT) is a promising modality for cancer treatment. However, limited tissue penetration of external radiation and complicated tumor microenvironments (TMEs) restrict the antitumor efficiency of PDT. Herein, we report an energy-storing DNA-based hydrogel, which enables tumor-selective PDT without external radiation and regulates TMEs to achieve boosted PDT-mediated tumor immunotherapy. The system is constructed with two ultralong single-stranded DNA chains, which programmed partial complementary sequences and repeated G-quadruplex forming AS1411 aptamer for photosensitizer loading via hydrophobic interactions and π-π stacking. Then, energy-storing persistent luminescent nanoparticles are incorporated to sensitize PDT selectively at tumor site without external irradiation, generating tumor antigen to agitate antitumor immune response. The system catalytically generates O2 to alleviate hypoxia and releases inhibitors to reverse the IDO-related immunosuppression, synergistically remodeling the TMEs. In the mouse model of breast cancer, this hydrogel shows a remarkable tumor suppression rate of 78.3 %. Our study represents a new paradigm of photodynamic immunotherapy against cancer by combining laser-free fashion and TMEs remodeling.

FSP1-mediated ferroptosis in cancer: from mechanisms to therapeutic applications

Ferroptosis is a new discovered regulated cell death triggered by the ferrous ion (Fe2+)-dependent accumulation of lipid peroxides associated with cancer and many other diseases. The mechanism of ferroptosis includes oxidation systems (such as enzymatic oxidation and free radical oxidation) and antioxidant systems (such as GSH/GPX4, CoQ10/FSP1, BH4/GCH1 and VKORC1L1/VK). Among them, ferroptosis suppressor protein 1 (FSP1), as a crucial regulatory factor in the antioxidant system, has shown a crucial role in ferroptosis. FSP1 has been well validated to ferroptosis in three ways, and a variety of intracellular factors and drug molecules can alleviate ferroptosis via FSP1, which has been demonstrated to alter the sensitivity and effectiveness of cancer therapies, including chemotherapy, radiotherapy, targeted therapy and immunotherapy. This review aims to provide important frameworks that, bring the regulation of FSP1 mediated ferroptosis into cancer therapies on the basis of existing studies.

Progress of proteolysis-targeting chimeras (PROTACs) delivery system in tumor treatment

Proteolysis targeting chimeras (PROTACs) can use the intrinsic protein degradation system in cells to degrade pathogenic target proteins, and are currently a revolutionary frontier of development strategy for tumor treatment with small molecules. However, the poor water solubility, low cellular permeability, and off-target side effects of most PROTACs have prevented them from passing the preclinical research stage of drug development. This requires the use of appropriate delivery systems to overcome these challenging hurdles and ensure precise delivery of PROTACs towards the tumor site. Therefore, the combination of PROTACs and multifunctional delivery systems will open up new research directions for targeted degradation of tumor proteins. In this review, we systematically reviewed the design principles and the most recent advances of various PROTACs delivery systems. Moreover, the constructive strategies for developing multifunctional PROTACs delivery systems were proposed comprehensively. This review aims to deepen the understanding of PROTACs drugs and promote the further development of PROTACs delivery system.

Enhancing in situ cancer vaccines using delivery technologies

In situ cancer vaccination refers to any approach that exploits tumour antigens available at a tumour site to induce tumour-specific adaptive immune responses. These approaches hold great promise for the treatment of many solid tumours, with numerous candidate drugs under preclinical or clinical evaluation and several products already approved. However, there are challenges in the development of effective in situ cancer vaccines. For example, inadequate release of tumour antigens from tumour cells limits antigen uptake by immune cells; insufficient antigen processing by antigen-presenting cells restricts the generation of antigen-specific T cell responses; and the suppressive immune microenvironment of the tumour leads to exhaustion and death of effector cells. Rationally designed delivery technologies such as lipid nanoparticles, hydrogels, scaffolds and polymeric nanoparticles are uniquely suited to overcome these challenges through the targeted delivery of therapeutics to tumour cells, immune cells or the extracellular matrix. Here, we discuss delivery technologies that have the potential to reduce various clinical barriers for in situ cancer vaccines. We also provide our perspective on this emerging field that lies at the interface of cancer vaccine biology and delivery technologies.

A dual-enzyme-like photosensitive nanozyme for remodeling the tumor immunosuppressive microenvironment to enhance immunotherapy

In "immune-cold" tumors, the upregulation of immunosuppressive cells and insufficient infiltration of lymphocytes contribute to the resistance against immune therapy. Herein, we have developed a dual-enzyme-like photosensitive nanozyme (PBAF) to remodel the tumor immunosuppressive microenvironment (TIME) and induce the tumor infiltration of cytotoxic T lymphocytes (CTLs). Specifically, PBAF exhibits peroxidase (POD)-like activity and glutathione oxidase (GSHOx)-like activity and can be stimulated by 750 nm laser, promoting oxidative stress at the tumor site. Consequently, this process further leads to the reconstruction of TIME in animal experiments, inducing tumor-associated macrophages (TAMs) toward the immunostimulatory M1 phenotype, eliminating myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). Simultaneously, PBAF also promotes dendritic cells (DCs) maturation to enhance CTLs infiltration into the tumor. The remodeled TIME and enhanced immune responses by PBAF demonstrate significant post-administration inhibition of recurrence and metastasis in the treatment of malignant tumors.

An artificial signaling pathway primitive-based intelligent biomimetic nanoenzymes carrier platform for precise treatment of Her2 (+) tumors

In tumor treatment, the deposition of nanoenzymes in normal tissues and cause potential side effects are unavoidable. Here, we designed an intelligent biomimetic nanoenzymes carrier platform (MSCintelligent) that endows the carrier platform with "wisdom" by introducing Affibody-Notch(core)-VP64-GAL4/UAS-HSV-TK artificial signal pathways to mesenchymal stem cells (MSCs). This intelligent nanoenzymes carrier platform is distinguished from the traditional targeting tumor microenvironment or enhancing affinity with tumor, which endue MSCintelligent with tumor signal recognition capacity, so that MSCintelligent can autonomously distinguish tumor from normal tissue cells and feedback edited instructions. In this study, MSCintelligent can convert tumor signals into HSV-TK instructions through artificial signal pathway after recognizing Her2 (+) tumor. Subsequently, the synthesized HSV-TK can rupture MSCintelligent under the mediation of ganciclovir, and release the preloaded Cu/Fe nanocrystal clusters to kill the tumor accurately. Meanwhile, MSCintelligent without recognizing tumors will not initiate the HSV-TK instructions, thus being unresponsive to GCV and blocking the release of nanoenzymes in normal tissues. Consequently, MSCintelligent is the first intelligent biomimetic nanoenzymes carrier platform, which represents a new biomimetic nanoenzymes targeting mode.

Cu2WS4-PEG Nanozyme as Multifunctional Sensitizers for Enhancing Immuno-Radiotherapy by Inducing Ferroptosis

Unavoidable damage to normal tissues and tumor microenvironment (TME) resistance make it challenging to eradicate breast carcinoma through radiotherapy. Therefore, it is urgent to develop radiotherapy sensitizers that can effectively reduce radiation doses and reverse the suppressive TME. Here, a novel biomimetic PEGylated Cu2WS4 nanozyme (CWP) with multiple enzymatic activities is synthesized by the sacrificing template method to have physical radiosensitization and biocatalyzer-responsive effects on the TME. Experiment results show that CWP can improve the damage efficiency of radiotherapy on breast cancer cell 4T1 through its large X-ray attenuation coefficient of tungsten and nucleus-penetrating capacity. CWP also exhibit strong Fenton-like reactions that produced abundant ROS and GSH oxidase-like activity decreasing GSH. This destruction of redox balance further promotes the effectiveness of radiotherapy. Transcriptome sequencing reveals that CWP induced ferroptosis by regulating the KEAP1/NRF2/HMOX1/GPX4 molecules. Therefore, owing to its multiple enzymatic activities, high-atomic W elements, nucleus-penetrating, and ferroptosis-inducing capacities, CWP effectively improves the efficiency of radiotherapy for breast carcinoma in vitro and in vivo. Furthermore, CWP-mediated radiosensitization can trigger immunogenic cell death (ICD) to improve the anti-PD-L1 treatments to inhibit the growth of primary and distant tumors effectively. These results indicate that CWP is a multifunctional nano-sensitizers for radiotherapy and immunotherapy.

Synergizing Pyroelectric Catalysis and Enzyme Catalysis: Establishing a Reciprocal and Synergistic Model to Enhance Anti-Tumor Activity

Nanozyme activity is greatly weakened by the microenvironment and multidrug resistance of tumor cells. Hence, a bi-catalytic nanoplatform, which promotes the anti-tumor activity through "charging empowerment" and "mutual complementation" processes involved in enzymatic and pyroelectric catalysis, by loading ultra-small nanoparticles (USNPs) of pyroelectric ZnSnO3 onto MXene nanozyme (V2CTx nanosheets), is developed. Here, the V2CTx nanosheets exhibit enhanced peroxidase activity by reacting V3+ with H2O2 to generate toxic ·OH, accelerated by the near-infrared (NIR) light mediated heat effect. The resulting V4+ is then converted to V3+ by oxidizing endogenous glutathione (GSH), realizing an enzyme-catalyzed cycle. However, the cycle will lose its persistence once GSH is insufficient; nevertheless, the pyroelectric charges generated by ZnSnO3 USNPs continuously support the V4+/V3+ conversion and ensure nanoenzyme durability. Moreover, the hyperthermia arising from the V2CTx nanosheets by NIR irradiation results in an ideal local temperature gradient for the ZnSnO3 USNPs, giving rise to an excellent pyroelectric catalytic effect by promoting band bending. Furthermore, polarized charges increase the tumor cell membrane permeability and facilitate nanodrug accumulation, thereby resolving the multidrug resistance issue. Thus, the combination of pyroelectric and enzyme catalysis together with the photothermal effect solves the dilemma of nanozymes and improves the antitumor efficiency.

Exosome-Inhibiting Polymeric Sonosensitizer for Tumor-Specific Sonodynamic Immunotherapy

Combination cancer immunotherapy based on electromagnetic energy and immunotherapy shows potent anti-cancer efficacy. However, as a factor that mediates tumor metastasis and immune suppression, the impact of tumor exosomes on therapy under electromagnetic energy stimulation remains unclear. Herein, findings indicate that sonodynamic therapy (SDT) increases serum exosome levels by inducing apoptotic exosomes and loosening the tumor extracellular matrix, promoting lung metastasis. To address this problem, an exosome-inhibiting polymeric sonosensitizer (EIPS) selectively inhibiting tumor exosome generation in response to the tumor biomarker is synthesized. EIPS consists of a semiconducting polymer backbone capable of inducing SDT and a poly(ethylene glycol) layer conjugated with a tumor-specific enzyme-responsive exosome inhibitor prodrug. After being cleaved by tumor Cathepsin B, EIPS releases active exosome inhibitors, preventing tumor exosome-mediated immune suppression and lung metastasis. As a result, EIPS elicits robust antitumor effects through the synergistic effect of SDT and tumor exosome inhibition, completely preventing lung metastasis and establishing a long-term immune memory effect. This is the first example showing that combining SDT with tumor-specific exosome inhibition can elicit a potent immune response without the help of typical immune agonists.

Dual-enzyme decorated semiconducting polymer nanoagents for second near-infrared photoactivatable ferroptosis-immunotherapy

Enzymes provide a class of potential options to treat cancer, while the precise regulation of enzyme activities for effective and safe therapeutic actions has been poorly reported. Dual-enzyme decorated semiconducting polymer nanoagents for second near-infrared (NIR-II) photoactivatable ferroptosis-immunotherapy are reported in this study. Such nanoagents (termed SPHGA) consist of hemoglobin (Hb)-based semiconducting polymer (SP@Hb), adenosine deaminase (ADA) and glucose oxidase (GOx) with loadings in a thermal-responsive nanoparticle shell. NIR-II photoactivation of SPHGA results in the generation of heat to trigger on-demand releases of two enzymes (ADA and GOx) via destroying the thermal-responsive nanoparticle shells. In the tumor microenvironment, GOx oxidizes glucose to form hydrogen peroxide (H2O2), which promotes the Fenton reaction of iron in SP@Hb, resulting in an enhanced ferroptosis effect and immunogenic cell death (ICD). In addition, ADA degrades high-level adenosine to reverse the immunosuppressive microenvironment, thus amplifying antitumor immune responses. Via NIR-II photoactivatable ferroptosis-immunotherapy, SPHGA shows an improved effect to absolutely remove bilateral tumors and effectively suppress tumor metastases in subcutaneous 4T1 breast cancer models. This study presents a dual-enzyme-based nanoagent with controllable therapeutic actions for effective and precise cancer therapy.

Personalized Nanovaccines Enhance Lymph Node Accumulation and Reprogram the Tumor Microenvironment for Improved Photodynamic Immunotherapy

Tumor immunotherapy has emerged as an efficacious therapeutic approach that mobilizes the patient's immune system to achieve durable tumor suppression. Here, we design a photodynamic therapy-motivated nanovaccine (Dex-HDL/ALA-Fe3O4) co-delivering 5-aminolevulinic acid and Fe3O4 nanozyme that demonstrate a long-term durable immunotherapy strategy. After vaccination, the nanovaccine exhibits obvious tumor site accumulation, lymph node homing, and specific and memory antitumor immunity evocation. Upon laser irradiation, Dex-HDL/ALA-Fe3O4 effectively generates reactive oxygen species at the tumor site not only to induce the immunogenic cell death-cascade but also to trigger the on-demand release of full types of tumor antigens. Intriguingly, Fe3O4 nanozyme-catalyzed hydrogen peroxide generated oxygen for alleviating tumor hypoxia and modifying the inhibitory tumor microenvironment, thereby exhibiting remarkable potential as a sensitizer. The intravenous administration of nanovaccines in diverse preclinical cancer models has demonstrated remarkable tumor regression and inhibition of postoperative tumor recurrence and metastasis, thereby enabling personalized treatment strategies against highly heterogeneous tumors.

Photosensitizer-Amplified Antimicrobial Materials for Broad-Spectrum Ablation of Resistant Pathogens in Ocular Infections

The emergence of multidrug resistant (MDR) pathogens and the scarcity of new potent antibiotics and antifungals are one of the biggest threats to human health. Antimicrobial photodynamic therapy (aPDT) combines light and photosensitizers to kill drug-resistant pathogens; however, there are limited materials that can effectively ablate different classes of infective pathogens. In the present work, a new class of benzodiazole-paired materials is designed as highly potent PDT agents with broad-spectrum antimicrobial activity upon illumination with nontoxic light. The results mechanistically demonstrate that the energy transfer and electron transfer between nonphotosensitive and photosensitive benzodiazole moieties embedded within pathogen-binding peptide sequences result in increased singlet oxygen generation and enhanced phototoxicity. Chemical optimization renders PEP3 as a novel PDT agent with remarkable activity against MDR bacteria and fungi as well as pathogens at different stages of development (e.g., biofilms, spores, and fungal hyphae), which also prove effective in an ex vivo porcine model of microbial keratitis. The chemical modularity of this strategy and its general compatibility with peptide-based targeting agents will accelerate the design of highly photosensitive materials for antimicrobial PDT.

Molybdesum selenide-based platelet-rich plasma containing carboxymethyl chitosan/polyvinyl pyrrolidone composite antioxidant hydrogels dressing promotes the wound healing

Excess free radicals at the wound site can cause an inflammatory response, which is not conducive to wound healing. Hydrogels with antioxidant properties can prevent inflammatory storms by scavenging free radicals from the wound site and inhibiting the release of inflammatory factors. In this study, we prepared the carboxymethyl chitosan (CMCS)/polyvinyl pyrrolidone (PVP)/Molybdenum (IV) Selenide (MoSe2), and platelet-rich plasma (PRP) (CMCS/PVP/MoSe2/PRP) hydrogels for accelerating the repair of wounds. In the hydrogels, the MoSe2 can scavenge various free radicals to reduce oxidative stress at the site of inflammation, endowed the hydrogels with antioxidant properties. Interestingly, growth factors released by PRP assisted the tissue repair by promoting the formation of new capillaries. CMCS as a backbone not only showed good biocompatibility and biodegradability but also played a significant role in maintaining the sustained release of growth factors. In addition, incorporating PVP enhanced the tissue adhesion and mechanical properties. The multifunctional composite antioxidant hydrogels have good swelling properties and biodegradability, which is completely degraded within 28 days. Thus, the antioxidant CMCS/PVP/MoSe2/PRP hydrogels provide a new idea for designing ideal multifunctional wound dressings.

Atomic Engineering of Single-Atom Nanozymes for Biomedical Applications

Single-atom nanozymes (SAzymes) showcase not only uniformly dispersed active sites but also meticulously engineered coordination structures. These intricate architectures bestow upon them an exceptional catalytic prowess, thereby captivating numerous minds and heralding a new era of possibilities in the biomedical landscape. Tuning the microstructure of SAzymes on the atomic scale is a key factor in designing targeted SAzymes with desirable functions. This review first discusses and summarizes three strategies for designing SAzymes and their impact on reactivity in biocatalysis. The effects of choices of carrier, different synthesis methods, coordination modulation of first/second shell, and the type and number of metal active centers on the enzyme-like catalytic activity are unraveled. Next, a first attempt is made to summarize the biological applications of SAzymes in tumor therapy, biosensing, antimicrobial, anti-inflammatory, and other biological applications from different mechanisms. Finally, how SAzymes are designed and regulated for further realization of diverse biological applications is reviewed and prospected. It is envisaged that the comprehensive review presented within this exegesis will furnish novel perspectives and profound revelations regarding the biomedical applications of SAzymes.

Metabolic Modulation of Kynurenine Based on Kynureninase-Loaded Nanoparticle Depot Overcomes Tumor Immune Evasion in Cancer Immunotherapy

Evading recognition of immune cells is a well-known strategy of tumors used for their survival. One of the immune evasion mechanisms is the synthesis of kynurenine (KYN), a metabolite of tryptophan, which suppresses the effector T cells. Therefore, lowering the KYN concentration can be an efficient antitumor therapy by restoring the activity of immune cells. Recently, kynureninase (KYNase), which is an enzyme transforming KYN into anthranilate, was demonstrated to show the potential to decrease KYN concentration and inhibit tumor growth. However, due to the limited bioavailability and instability of proteins in vivo, it has been challenging to maintain the KYNase concentration sufficiently high in the tumor microenvironment (TME). Here, we developed a nanoparticle system loaded with KYNase, which formed a Biodegradable and Implantable Nanoparticle Depot named 'BIND' following subcutaneous injection. The BIND sustainably supplied KYNase around the TME while located around the tumor, until it eventually degraded and disappeared. As a result, the BIND system enhanced the proliferation and cytokine production of effector T cells in the TME, followed by tumor growth inhibition and increased mean survival. Finally, we showed that the BIND carrying KYNase significantly synergized with PD-1 blockade in three mouse models of colon cancer, breast cancer, and melanoma.

The Application of Nanoparticles Targeting Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAF) are the most abundant stromal cells in the tumor microenvironment (TME), especially in solid tumors. It has been confirmed that it can not only interact with tumor cells to promote cancer progression and metastasis, but also affect the infiltration and function of immune cells to induce chemotherapy and immunotherapy resistance. So, targeting CAF has been considered an important method in cancer treatment. The rapid development of nanotechnology provides a good perspective to improve the efficiency of targeting CAF. At present, more and more researches have focused on the application of nanoparticles (NPs) in targeting CAF. These studies explored the effects of different types of NPs on CAF and the multifunctional nanomedicines that can eliminate CAF are able to enhance the EPR effect which facilitate the anti-tumor effect of themselves. There also exist amounts of studies focusing on using NPs to inhibit the activation and function of CAF to improve the therapeutic efficacy. The application of NPs targeting CAF needs to be based on an understanding of CAF biology. Therefore, in this review, we first summarized the latest progress of CAF biology, then discussed the types of CAF-targeting NPs and the main strategies in the current. The aim is to elucidate the application of NPs in targeting CAF and provide new insights for engineering nanomedicine to enhance immune response in cancer treatment.

An Activatable Dual Polymer Nanosystem for Photoimmunotherapy and Metabolic Modulation of Deep-Seated Tumors

Nanomedicine in combination with immunotherapy has shown great potential in the cancer treatment, but phototherapeutic nanomaterials that specifically activate the immunopharmacological effects in deep tumors have rarely been developed due to limited laser penetration depth and tumor immune microenvironment. Herein, this work reports a newly synthesized semiconducting polymer (SP) grafted with imiquimod R837 and indoxmid encapsulated micelle (SPRIN-micelle) with strong absorption in the second near infrared window (NIR-II) that can relieve tumor immunosuppression and enhance the photothermal immunotherapy and catabolic modulation on tumors. Immune agonists (Imiquimod R837) and immunometabolic modulators (indoxmid) are covalently attached to NIR-II SP sensors via a glutathione (GSH) responsive self-immolation linker and then loaded into Pluronic F127 (F127) micelles by a temperature-sensitive critical micelle concentration (CMC)-switching method. Using this method, photothermal effect of SPRIN-micelles in deep-seated tumors can be activated, leading to effective tumor ablation and immunogenic cell death (ICD). Meanwhile, imiquimod and indoxmid are tracelessly released in response to the tumor microenvironment, resulting in dendritic cell (DC) maturation by imiquimod R837 and inhibition of both indoleamine 2,3-dioxygenase (IDO) activity and Treg cell expression by indoxmid. Ultimately, cytotoxic T-lymphocyte infiltration and tumor metastasis inhibition in deep solid tumors (9 mm) are achieved. In summary, this work demonstrates a new strategy for the combination of photothermal immunotherapy and metabolic modulation by developing a dual functional polymer system including activable SP and temperature-sensitive F127 for the treatment of deep solid tumors.

MnO2/Ce6 microbubble-mediated hypoxia modulation for enhancing sono-photodynamic therapy against triple negative breast cancer

Sono-photodynamic therapy (SPDT) has emerged as a promising treatment modality for triple negative breast cancer (TNBC). However, the hypoxic tumor microenvironment hinders the application of SPDT. Herein, in this study, a multifunctional platform (MnO2/Ce6@MBs) was designed to address this issue. A sono-photosensitizer (Ce6) and a hypoxia modulator (MnO2) were loaded into microbubbles and precisely released within tumor tissues under ultrasound irradiation. MnO2in situ reacted with the excess H2O2 and H+ and produced O2 within the TNBC tumor, which alleviated hypoxia and augmented SPDT by increasing ROS generation. Meanwhile, the reaction product Mn2+ was able to achieve T1-weighted MRI for enhanced tumor imaging. Additionally, Ce6 and microbubbles served as a fluorescence imaging contrast agent and a contrast-enhanced ultrasound imaging agent, respectively. In in vivo anti-tumor studies, under the FL/US/MR imaging guidance, MnO2/Ce6@MBs combined with SPDT significantly reversed tumor hypoxia and inhibited tumor growth in 4T1-tumor bearing mice. This work presents a theragnostic system for reversing tumor hypoxia and enhancing TNBC treatment.

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.

A Defect-Engineered Nanozyme for Targeted NIR-II Photothermal Immunotherapy of Cancer

Multienzyme-mimicking redox nanozymes, curated by defect engineering, in synergy with immunotherapy offer promising prospects for safe and efficient cancer therapy. However, the spatiotemporally precise immune response often gets challenged by off-target adverse effects and insufficient therapeutic response. Herein, a tumor cell membrane coated redox nanozyme (CMO-R@4T1) is reported for combinational second near-infrared window (NIR-II) photothermal immunotherapy. CMO-R@4T1 consists of a Cu-doped MoOx (CMO) nanozyme as the core, which is cloaked with tumor-cell-derived fused membranes with immunostimulants immobilized in the membrane shell. In addition to the enhanced tumor accumulation, the nanozyme can cause oxidative damage to tumor cells by the production of reactive oxygen species and attenuation of the antioxidant mechanism. CMO-R@4T1 also mediates a photothermal effect under NIR-II photoirradiation to trigger tumor eradication and immunogenic cell death, where the liberated agonist elicits the immune activation. Such a controlled therapeutic paradigm potentiates systemic primary tumor ablation, inhibits cancer metastasis to distant tumor, and procures long-term immunological memory. Thereby, this study takes advantage of defect engineering to illustrate a generic strategy to prepare cell-membrane-camouflaged nanozymes for targeted photo-immunotherapy of cancer.

Toward Type I/II ROS Generation Photoimmunotherapy by Molecular Engineering of Semiconducting Perylene Diimide

As prospective phototheranostic agents for cancer imaging and therapy, semiconducting organic molecule-based nanomedicines are developed. However, near-infrared (NIR) emission, and tunable type I (O2 • -) and type II (1O2) photoinduced reactive oxygen species (ROS) generation to boost cancer photoimmunotherapy remains a big challenge. Herein, a series of D-π-A structures, NIR absorbing perylene diimides (PDIs) with heavy atom bromide modification at the bay position of PDIs are prepared for investigating the optimal photoinduced type I/II ROS generation. The heavy atom effect has demonstrated a reduction of molecular ∆EST and promotion of the intersystem crossing processes of PDIs, enhancing the photodynamic therapy (PDT) efficacy. The modification of three bromides and one pyrrolidine at the bay position of PDI (TBDT) has demonstrated the best type I/II PDT performance by batch experiments and theoretical calculations. TBDT based nanoplatforms (TBDT NPs) enable type I/II PDT in the hypoxic tumor microenvironment as a strong immunogenic cell death (ICD) inducer. Moreover, TBDT NPs showing NIR emission allow in vivo bioimaging guided phototherapy of tumor. This work uses novel PDIs with adjustable type I/II ROS production to promote antitumor immune response and accomplish effective tumor eradication, consequently offering molecular guidelines for building high-efficiency ICD inducers.

Leveraging Semiconducting Polymer Nanoparticles for Combination Cancer Immunotherapy

Cancer immunotherapy has become a promising method for cancer treatment, bringing hope to advanced cancer patients. However, immune-related adverse events caused by immunotherapy also bring heavy burden to patients. Semiconducting polymer nanoparticles (SPNs) as an emerging nanomaterial with high biocompatibility, can eliminate tumors and induce tumor immunogenic cell death through different therapeutic modalities, including photothermal therapy, photodynamic therapy, and sonodynamic therapy. In addition, SPNs can work as a functional nanocarrier to synergize with a variety of immunomodulators to amplify anti-tumor immune responses. In this review, SPNs-based combination cancer immunotherapy is comprehensively summarized according to the SPNs' therapeutic modalities and the type of loaded immunomodulators. The in-depth understanding of existing SPNs-based therapeutic modalities will hopefully inspire the design of more novel nanomaterials with potent anti-tumor immune effects, and ultimately promote their clinical translation.

Hydrophobic ion pairing and microfluidic nanoprecipitation enable efficient nanoformulation of a small molecule indolamine 2, 3-dioxygenase inhibitor immunotherapeutic

Blockade of programmed cell death-1 (PD-1) is a transformative immunotherapy. However, only a fraction of patients benefit, and there is a critical need for broad-spectrum checkpoint inhibition approaches that both enhance the recruitment of cytotoxic immune cells in cold tumors and target resistance pathways. Indoleamine 2, 3-dioxygenase (IDO) small molecule inhibitors are promising but suboptimal tumor bioavailability and dose-limiting toxicity have limited therapeutic benefits in clinical trials. This study reports on a nanoformulation of the IDO inhibitor navoximod within polymeric nanoparticles prepared using a high-throughput microfluidic mixing device. Hydrophobic ion pairing addresses the challenging physicochemical properties of navoximod, yielding remarkably high loading (>10%). The nanoformulation efficiently inhibits IDO and, in synergy with PD-1 antibodies improves the anti-cancer cytotoxicity of T-cells, in vitro and in vivo. This study provides new insight into the IDO and PD-1 inhibitors synergy and validates hydrophobic ion pairing as a simple and clinically scalable formulation approach.

Stimuli-Responsive Polymer-Based Nanosystems for Cancer Theranostics

Stimuli-responsive polymers can respond to internal stimuli, such as reactive oxygen species (ROS), glutathione (GSH), and pH, biological stimuli, such as enzymes, and external stimuli, such as lasers and ultrasound, etc., by changing their hydrophobicity/hydrophilicity, degradability, ionizability, etc., and thus have been widely used in biomedical applications. Due to the characteristics of the tumor microenvironment (TME), stimuli-responsive polymers that cater specifically to the TME have been extensively used to prepare smart nanovehicles for the targeted delivery of therapeutic and diagnostic agents to tumor tissues. Compared to conventional drug delivery nanosystems, TME-responsive nanosystems have many advantages, such as high sensitivity, broad applicability among different tumors, functional versatility, and improved biosafety. In recent years, a great deal of research has been devoted to engineering efficient stimuli-responsive polymeric nanosystems, and significant improvement has been made to both cancer diagnosis and therapy. In this review, we summarize some recent research advances involving the use of stimuli-responsive polymer nanocarriers in drug delivery, tumor imaging, therapy, and theranostics. Various chemical stimuli will be described in the context of stimuli-responsive nanosystems. Accordingly, the functional chemical groups responsible for the responsiveness and the strategies to incorporate these groups into the polymer will be discussed in detail. With the research on this topic expending at a fast pace, some innovative concepts, such as sequential and cascade drug release, NIR-II imaging, and multifunctional formulations, have emerged as popular strategies for enhanced performance, which will also be included here with up-to-date illustrations. We hope that this review will offer valuable insights for the selection and optimization of stimuli-responsive polymers to help accelerate their future applications in cancer diagnosis and treatment.

Nanomedicine-Enabled Chemical Regulation of Reactive X Species for Versatile Disease Treatments

Reactive X species (RXS), encompassing elements such as O, N, C, S, Se, Cl, Br, I, and H, play vital roles in cell biology and physiological function, impacting cellular signal transduction, metabolic regulation, and disease processes. The redox unbalance of RXS is firmly implicated in an assortment of physiological and pathological disorders, including cancer, diabetes, cardiovascular disease, and neurodegenerative diseases. However, the intricate nature and multifactorial dependence of RXS pose challenges in comprehending and precisely modulating their biological behavior. Nanomaterials with distinct characteristics and biofunctions offer promising avenues for generating or scavenging RXS to maintain redox homeostasis and advance disease therapy. This minireview provides a tutorial summary of the relevant chemistry and specific mechanisms governing different RXS, focusing on cellular metabolic regulation, stress responses, and the role of nanomedicine in RXS generation and elimination. The challenges associated with chemically regulating RXS for diverse disease treatments are further discussed along with the future prospects, aiming to facilitate the clinical translation of RXS-based nanomedicine and open new avenues for improved therapeutic interventions.

Semiconducting Polymers for Cancer Immunotherapy

As a monumental breakthrough in cancer treatment, immunotherapy has attracted tremendous attention in recent years. However, one challenge faced by immunotherapy is the low response rate and the immune-related adverse events (irAEs). Therefore, it is important to explore new therapeutic strategies and platforms for boosting therapeutic benefits and decreasing the side effects of immunotherapy. In recent years, semiconducting polymer (SP), a category of organic materials with π-conjugated aromatic backbone, has been attracting considerable attention because of their outstanding characteristics such as excellent photophysical features, good biosafety, adjustable chemical flexibility, easy fabrication, and high stability. With these distinct advantages, SP is extensively explored for bioimaging and photo- or ultrasound-activated tumor therapy. Here, the recent advancements in SP-based nanomedicines are summarized for enhanced tumor immunotherapy. According to the photophysical properties of SPs, the cancer immunotherapies enabled by SPs with the photothermal, photodynamic, or sonodynamic functions are highlighted in detail, with a particular focus on the construction of combination immunotherapy and activatable nanoplatforms to maximize the benefits of cancer immunotherapy. Herein, new guidance and comprehensive insights are provided for the design of SPs with desired photophysical properties to realize maximized effectiveness of required biomedical applications.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Tumor Metabolism-Rewriting Nanomedicines for Cancer Immunotherapy

Cancer immunotherapy has become an established therapeutic paradigm in oncologic therapy, but its therapeutic efficacy remains unsatisfactory in the majority of cancer patients. Accumulating evidence demonstrates that the metabolically hostile tumor microenvironment (TME), characterized by acidity, deprivation of oxygen and nutrients, and accumulation of immunosuppressive metabolites, promotes the dysfunction of tumor-infiltrating immune cells (TIICs) and thereby compromises the effectiveness of immunotherapy. This indicates the potential role of tumor metabolic intervention in the reinvigoration of antitumor immunity. With the merits of multiple drug codelivery, cell and organelle-specific targeting, controlled drug release, and multimodal therapy, tumor metabolism-rewriting nanomedicines have recently emerged as an attractive strategy to strengthen antitumor immune responses. This review summarizes the current progress in the development of multifunctional tumor metabolism-rewriting nanomedicines for evoking antitumor immunity. A special focus is placed on how these nanomedicines reinvigorate innate or adaptive antitumor immunity by regulating glucose metabolism, amino acid metabolism, lipid metabolism, and nucleotide metabolism at the tumor site. Finally, the prospects and challenges in this emerging field are discussed.

Design and Mechanism Insight of Monodispersed AuCuPt Alloy Nanozyme with Antitumor Activity

The abrogation of the self-adaptive redox evolution of tumors is promising for improving therapeutic outcomes. In this study, we designed a trimetallic alloy nanozyme AuCuPt-PpIX (ACPP), which mimics up to five naturally occurring enzymes: glucose oxidase (GOD), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione peroxidase (GPx). Facilitated by these enzyme-mimicking traits, the constructed ACPP nanozymes can not only disrupt the established redox homeostasis in tumors through a series of enzymatic cascade reactions but also achieve cyclic regeneration of the relevant enzyme substrates. Density functional theory (DFT) calculations have theoretically explained the synergistic effect of multimetallic doping and the possible mechanism of enzymatic catalysis. The doped Cu and Pt sites are conducive to the adsorption, activation, and dissociation of reactant molecules, whereas the Au sites are conducive to desorption, which significantly improves catalytic efficiency via a synergistic effect. Additionally, ACPP nanozymes can improve the effect of protoporphyrin (PpIX)-enabled sonodynamic therapy (SDT) by alleviating hypoxia and initiating ferroptosis by inducing lipid peroxidation (LPO) and inhibiting GPX4 activity, thus achieving multimodal synergistic therapy. This study presents a typical paradigm to enable the use of multimetallic alloy nanozymes for the treatment of tumor cells with self-adaptive properties.

pH-Activated Scallop-Type Nanoenzymes for Oxidative Stress Amplification and Photothermal Enhancement of Antibacterial and Antibiofilm Effect

Ferric phosphate (FePOs) nanoenzymes can express peroxidase (POD) activity under the dual stimulation of an acidic environment and high H2O2 concentrations. In living organisms, this generates reactive oxygen species (ROS) in sites of lesion infection, and thus FePOs nanoenzymes can act as antimicrobial agents. Here, CeO2 and ZnO2 were immobilized in a scallop-type FePOs nanoenzyme material loaded with a photosensitizer, indocyanine green, to synthesize a multifunctional cascade nanoparticle system (FePOs-CeO2-ZnO2-ICG, FCZI NPs). H2O2 concentrations could be adjusted through the ZnO2 self-activation response to the slightly acidic environment in biofilms, further promoting the release of ROS from the POD-like reaction of FePOs, achieving amplification of oxidative stress, DNA and cell membrane damage, and exploiting the photodynamic/photothermal effects of indocyanine green to enhance the antibiofilm effects. CeO2 can remove redundant ROS by switching from Ce4+ to Ce3+ valence, enhancing its ability to fight chronic inflammation and oxidative stress and thus promoting the regeneration of tissues around infection. By maintaining the redox balance of normal cells, increasing ROS at the infection site, eliminating redundant ROS, and protecting normal tissues from damage, the synthesized system maximizes the elimination of biofilms and treatment at the infection site. Therefore, this work may pave the way for the application of biocompatible nanoenzymes.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

The kynurenine pathway presents multi-faceted metabolic vulnerabilities in cancer

The kynurenine pathway (KP) and associated catabolites play key roles in promoting tumor progression and modulating the host anti-tumor immune response. To date, considerable focus has been on the role of indoleamine 2,3-dioxygenase 1 (IDO1) and its catabolite, kynurenine (Kyn). However, increasing evidence has demonstrated that downstream KP enzymes and their associated metabolite products can also elicit tumor-microenvironment immune suppression. These advancements in our understanding of the tumor promotive role of the KP have led to the conception of novel therapeutic strategies to target the KP pathway for anti-cancer effects and reversal of immune escape. This review aims to 1) highlight the known biological functions of key enzymes in the KP, and 2) provide a comprehensive overview of existing and emerging therapies aimed at targeting discrete enzymes in the KP for anti-cancer treatment.

Sonodynamic Cytokine Nanocomplexes with Specific Stimulation towards Effector T Cell for Combination Cancer Immunotherapy

Cytokine therapy mediates the interaction between immune cells and non-immune cells in the tumor microenvironment (TME), forming a promising approach in cancer therapy. However, the dose-dependent adverse effects and non-selective stimulation of cytokines limit their clinical use. We herein report a sonodynamic cytokine nano-immunocomplex (SPNAI ) that specifically activates effector T cells (Teffs) for antitumor immunotherapy. By conjugating anti-interleukin-2 (anti-IL-2) antibodies S4B6 on the semiconducting polymer nanoparticles to afford SPNA , this nanoantibody SPNA can bind with IL-2 to form SPNAI which can block the interaction between IL-2 and regulatory T cells (Tregs), selectively activating Teffs in TME. Moreover, SPNAI generates 1 O2 to trigger immunogenic cell death of cancer cells upon sono-irradiation, which promotes the maturation of dendritic cells and the proliferation of Teffs. This SPNAI -mediated combination sonodynamic immunotherapy thus elevates the ratio of Teffs/Tregs in TME, resulting in inhibition of tumor growth, suppression of lung metastasis and prevention of tumor relapse.

Sm/Co-Doped Silica-Based Nanozymes Reprogram Tumor Microenvironment for ATP-Inhibited Tumor Therapy

Current applications of multifunctional nanozymes for reprogramming the redox homeostasis of the tumor microenvironment (TME) have been severely confronted with low catalytic activity and the ambiguity of active sites of nanozymes, as well as the stress resistance from the rigorous physical environment of tumor cells. Herein, the Sm/Co-doped mesoporous silica with 3PO-loaded nanozymes (denoted as mSC-3PO) are rationally constructed for simultaneously inhibiting energy production by adenosine triphosphate (ATP) inhibitor 3PO and reprogramming TME by multiactivities of nanozymes with photothermal effect assist, i.e., enhanced peroxidase-like, catalase-like activity, and glutathione peroxidase-like activities, facilitating reactive oxygen species (ROS) generation, promoting oxygen content, and restraining the over-expressed glutathione. Through the optimal regulation of nanometric size and doping ratio, the fabricated superparamagnetic mSC-3PO enables the excellent exposure of active sites and avoids agglomeration owing to the large specific surface and mesoporous structure, thus providing adequate Sm/Co-doped active sites and enough spatial distribution. The constructed Sm/Co centers both participate in the simulated biological enzyme reactions and carry out the double-center catalytic process (Sm3+ and Co3+ /Co2+ ). Significantly, as the inhibitor of glycolysis, 3PO can reduce the ATP flow by cutting down the energy transform, thereby inhibiting tumor angiogenesis and assisting ROS to promote the early withering of tumor cells. In addition, the considerable near-infrared (NIR) light absorption of mSC-3PO can adapt to NIR excitable photothermal treatment therapy and photoexcitation-promoted enzymatic reactions. Taken together, this work presents a typical therapeutic paradigm of multifunctional nanozymes that simultaneously reprograms TME and promotes tumor cell apoptosis with photothermal assistance.

Dendritic Cell Vaccines: A Shift from Conventional Approach to New Generations

In the emerging era of cancer immunotherapy, immune checkpoint blockades (ICBs) and adoptive cell transfer therapies (ACTs) have gained significant attention. However, their therapeutic efficacies are limited due to the presence of cold type tumors, immunosuppressive tumor microenvironment, and immune-related side effects. On the other hand, dendritic cell (DC)-based vaccines have been suggested as a new cancer immunotherapy regimen that can address the limitations encountered by ICBs and ACTs. Despite the success of the first generation of DC-based vaccines, represented by the first FDA-approved DC-based therapeutic cancer vaccine Provenge, several challenges remain unsolved. Therefore, new DC vaccine strategies have been actively investigated. This review addresses the limitations of the currently most adopted classical DC vaccine and evaluates new generations of DC vaccines in detail, including biomaterial-based, immunogenic cell death-inducing, mRNA-pulsed, DC small extracellular vesicle (sEV)-based, and tumor sEV-based DC vaccines. These innovative DC vaccines are envisioned to provide a significant breakthrough in cancer immunotherapy landscape and are expected to be supported by further preclinical and clinical studies.

Self-triggered thermoelectric nanoheterojunction for cancer catalytic and immunotherapy

The exogenous excitation requirement and electron-hole recombination are the key elements limiting the application of catalytic therapies. Here a tumor microenvironment (TME)-specific self-triggered thermoelectric nanoheterojunction (Bi0.5Sb1.5Te3/CaO2 nanosheets, BST/CaO2 NSs) with self-built-in electric field facilitated charge separation is fabricated. Upon exposure to TME, the CaO2 coating undergoes rapid hydrolysis, releasing Ca2+, H2O2, and heat. The resulting temperature difference on the BST NSs initiates a thermoelectric effect, driving reactive oxygen species production. H2O2 not only serves as a substrate supplement for ROS generation but also dysregulates Ca2+ channels, preventing Ca2+ efflux. This further exacerbates calcium overload-mediated therapy. Additionally, Ca2+ promotes DC maturation and tumor antigen presentation, facilitating immunotherapy. It is worth noting that the CaO2 NP coating hydrolyzes very slowly in normal cells, releasing Ca2+ and O2 without causing any adverse effects. Tumor-specific self-triggered thermoelectric nanoheterojunction combined catalytic therapy, ion interference therapy, and immunotherapy exhibit excellent antitumor performance in female mice.

Engineering Au44 Nanoclusters for NIR-II Luminescence Imaging-Guided Photoactivatable Cancer Immunotherapy

Immunotherapy is an advanced therapeutic strategy of cancer treatment but suffers from the issues of off-target adverse effects, lack of real-time monitoring techniques, and unsustainable response. Herein, an ultrasmall Au nanocluster (NC)-based theranostic probe is designed for second near-infrared window (NIR-II) photoluminescence (PL) imaging-guided phototherapies and photoactivatable cancer immunotherapy. The probe (Au44MBA26-NLG for short) is composed of atomically precise and NIR-II emitting Au44MBA26 NCs (here MBA denotes water-soluble 4-mercaptobenzoic acid) conjugated with immune checkpoint inhibitor 1-cyclohexyl-2-(5H-imidazo[5,1-a]isoindol-5-yl)ethanol (NLG919) via a singlet oxygen (1O2)-cleavable linker. Upon NIR photoirradiation, the Au44MBA26-NLG not only enables NIR-II PL imaging of tumors in deep tissues for guiding tumor therapy but also allows the leverage of photothermal property for cancer photothermal therapy (PTT) and the photogenerated 1O2 for photodynamic therapy (PDT) and releasing NLG919 for cancer immunotherapy. Such a multiple effect modulated by Au44MBA26-NLG prompts the proliferation and activation of effector T cells, upshifts systemic antitumor T-lymphocyte (T cell) immunity, and finally suppresses the growth of both primary and distant tumors in living mice. Overall, this study may provide a promising theranostic nanoplatform toward NIR-II PL imaging-guided phototherapies and photoactivatable cancer immunotherapy.

Nanozyme: a rising star for cancer therapy

In recent years, nanozymes have attracted enormous attention due to their effectiveness in promoting various catalytic reactions. To date, thousands of nanozymes have been discovered, including oxidase-like nanozymes, peroxidase-like nanozymes, and catalase-like nanozymes, covering noble metal, transition metal, and carbon nanomaterials. These nanozymes have been widely applied in various fields, including environmental protection, biosensing and nanomedicine. There are many reviews about this rising star being used in analytical chemistry. However, few works about nanozymes were related to cancer therapy. In this study, we comprehensively summarize the latest research advances on the strategies for cancer therapy based on different nanozymes. With traditional cancer treatment (including chemotherapy, radiotherapy, phototherapy), nanozyme catalytic therapy exhibited a synergistic effect for limiting the growth of tumors. Opportunities and trends for nanozymes in future cancer therapy are also discussed.

External cold atmospheric plasma-responsive on-site hydrogel for remodeling tumor immune microenvironment

Although immunotherapy has recently emerged as a promising anti-tumor approach, it remains limited by the immunosuppressive tumor microenvironment. Cold atmospheric plasma irradiation can generate reactive oxygen species and trigger the presentation of tumor-associated antigens. Here, we exploited cold atmospheric plasma for on-site hydrogel application in the tumor environment, aiming to facilitate the sustainable uptake of tumor-associated antigens and nanoadjuvants by dendritic cells. Hyaluronic acid-tyramine conjugate was intratumorally injected as a liquid and formed an on-site hydrogel under irradiation with cold atmospheric plasma. Intratumoral delivery of hyaluronic acid-tyramine conjugate with transforming growth factor β-blocking nanoadjuvant (TLN) followed by cold atmospheric plasma irradiation yielded a micro-network of TLN-loaded hydrogel (TLN@CHG). In vivo intratumoral injection of TLN@CHG promoted the activation of dendritic cells and more effectively increased the proportion of CD4 T cells and CD8 T cells in the tumor microenvironment, compared to the groups receiving TLN or hydrogel alone. Moreover, in CT26 tumor model mice, cold atmospheric plasma-induced TLN@CHG therapy ablated the primary tumor and provided 100% survival among mice rechallenged with CT26 cells. Taken together, our findings suggest that an on-site hydrogel-based micro-network of TLN has the potential to remodel the tumor immune microenvironment. Although we used TLN in this study, the concept could be extended to support the sustained action of other nanoadjuvants in a hydrogel micro-network.

Nanotechnology-based photo-immunotherapy: a new hope for inhibition of melanoma growth and metastasis

Melanoma is the most aggressive form of skin cancer and there is a need for the development of effective anti-melanoma therapies as it shows high metastatic ability and low response rate. In addition, it has been identified that traditional phototherapy could trigger immunogenic cell death (ICD) to activate antitumor immune response, which could not only effectively arrest primary tumor growth, but also exhibit superior effects in terms of anti-metastasis, anti-recurrence for metastatic melanoma treatment However, the limited tumor accumulation of photosensitizers/photothermal agents and immunosuppressive tumor microenvironment severely weaken the immune effects. The application of nanotechnology facilitates a higher accumulation of photosensitizers/photothermal agents at the tumor site, which can thus improve the antitumor effects of photo-immunotherapy (PIT). In this review, we summarize the basic principles of nanotechnology-based PIT and highlight novel nanotechnologies that are expected to enhance the antitumor immune response for improved therapeutic efficacy.

Proteolysis-targeting chimeras in biotherapeutics: Current trends and future applications

The success of inhibitor-based therapeutics is largely constrained by the acquisition of therapeutic resistance, which is partially driven by the undruggable proteome. The emergence of proteolysis targeting chimera (PROTAC) technology, designed for degrading proteins involved in specific biological processes, might provide a novel framework for solving the above constraint. A heterobifunctional PROTAC molecule could structurally connect an E3 ubiquitin ligase ligand with a protein of interest (POI)-binding ligand by chemical linkers. Such technology would result in the degradation of the targeted protein via the ubiquitin-proteasome system (UPS), opening up a novel way of selectively inhibiting undruggable proteins. Herein, we will highlight the advantages of PROTAC technology and summarize the current understanding of the potential mechanisms involved in biotherapeutics, with a particular focus on its application and development where therapeutic benefits over classical small-molecule inhibitors have been achieved. Finally, we discuss how this technology can contribute to developing biotherapeutic drugs, such as antivirals against infectious diseases, for use in clinical practices.

Near-infrared absorbing semiconducting polymer nanomedicines for cancer therapy

As a new type of organic optical nanomaterials, semiconducting polymer nanoparticles (SPNs) have the advantages of good optical characteristics and photostability, low toxicity concerns, and relatively simple preparation processes. Particularly, near-infrared (NIR) absorbing SPNs have shown a great promise in biomedicine. In addition to acting as nanoprobes for molecular imaging, these SPNs can produce local heat and reactive oxygen species with the stimulation of NIR light, allowing photothermal therapy (PTT) and photodynamic therapy (PDT), respectively. Herein, we summarize the recent development of SPN-based nanomedicines for cancer therapy. The rational designs of SPNs for enhanced PTT, PDT, or combinational PTT/PDT to achieve effective ablation of tumor tissues are highlighted. Via loading/conjugating SPNs with other therapeutic elements (such as chemotherapeutic drugs and immunotherapeutic agents), phototherapy-combined chemotherapy or immunotherapy can be realized, which is then discussed. In especial, the constructions of SPN-based nanomedicines for NIR photoactivatable chemotherapy and immunotherapy are introduced with representative examples. Finally, we discuss the current challenges and key concerns of SPNs for their biomedical applications and give an outlook for their future clinical translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Activating Nanomedicines with Electromagnetic Energy for Deep-Tissue Induction of Immunogenic Cell Death in Cancer Immunotherapy

Immunotherapy is an attractive approach for cancer therapy, while its antitumor efficacy is still limited, especially for non-immunogenic tumors. Nanomedicines can be utilized to convert the non-immunogenic "cold" tumors to immunogenic "hot" tumors via inducing immunogenic cell death (ICD), thereby promoting the antitumor immune response. Some nanomedicines that can produce local heat and reactive oxygen species upon the stimulation of electromagnetic energy are the main candidates for inducing the ICD effect. However, their applications are often restricted due to the poor tissue penetration depths of electromagnetic energy, such as light. By contrast, ultrasound, X-ray, alternating magnetic field, and microwave show excellent tissue penetration depths and thereby can be used for sonodynamic therapy, radiotherapy, magnetic hyperthermia therapy, and microwave ablation therapy, all of which can effectively induce ICD. Herein, the combination of deep-tissue electromagnetic energy with nanomedicines for inducing ICD and cancer immunotherapy are summarized. In particular, the designs of nanomedicines to amplify ICD effect in the presence of deep-tissue electromagnetic energy and sensitize tumors to various immunotherapies will be discussed. At the end of this review, a brief conclusion and discussion of current challenges and further perspectives in this subfield are provided.

Semiconducting Titanate Supported Ruthenium Clusterzymes for Ultrasound-Amplified Biocatalytic Tumor Nanotherapies

The external-stimulation-induced reactive-oxygen-species (ROS) generation has attracted increasing attention in therapeutics for malignant tumors. However, engineering a nanoplatform that integrates with efficient biocatalytic ROS generation, ultrasound-amplified ROS production, and simultaneous relief of tumor hypoxia is still a great challenge. Here, we create new semiconducting titanate-supported Ru clusterzymes (RuNC/BTO) for ultrasound-amplified biocatalytic tumor nanotherapies. The morphology and chemical/electronic structure analysis prove that the biocatalyst consists of Ru nanoclusters that are tightly stabilized by Ru-O coordination on BaTiO₃ . The peroxidase (POD)- and halogenperoxidase-like biocatalysis reveals that the RuNC/BTO can produce abundant •O₂ ^- radicals. Notably, the RuNC/BTO exhibits the highest turnover number (63.29 × 10^-3 s^-1 ) among the state-of-the-art POD-mimics. Moreover, the catalase-like activity of the RuNC/BTO facilitates the decomposition of H₂ O₂ to produce O₂ for relieving the hypoxia of the tumor and amplifying the ROS level via ultrasound irradiation. Finally, the systematic cellular and animal experiments have validated that the multi-modal strategy presents superior tumor cell-killing effects and suppression abilities. We believe that this work will offer an effective clusterzyme that can adapt to the tumor microenvironment-specific catalytic therapy and also provide a new pathway for engineering high-performance ROS production materials across broad therapeutics and biomedical fields.

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.

A CaCO3-based synergistic immunotherapy strategy for treating primary and distal tumors

Low response rate limits the widespread application of cancer immunotherapy. To improve the response rate of immunotherapy, a CaCO₃-based composite nanomaterial was developed to induce immunogenic cell death for enhancing immunotherapy against 4T1 primary and distal tumors.

Pyroptosis-Mediated Synergistic Photodynamic and Photothermal Immunotherapy Enabled by a Tumor-Membrane-Targeted Photosensitive Dimer

Overcoming the resistance to apoptosis and immunosuppression of tumor cells is a significant challenge in augmenting the effect of cancer immunotherapy. Pyroptosis, a lytic programmed cell-death pathway unlike apoptosis, is considered a type of immunogenic cell death (ICD) that can intensify the ICD process in tumor cells, releasing dramatically increased tumor-associated antigens and damage-associated molecular patterns to promote cancer immunotherapy. Herein, a tumor cell membrane-targeted aggregation-induced emission photosensitive dimer is found to be able to achieve highly efficient ICD under the synergistic effect of photodynamic and photothermal therapy. The photosensitive dimer can efficiently produce type-I reactive oxygen species (ROS) by photodynamic therapy in hypoxic tumor tissue, leading to pyroptosis by direct cell membrane damage, which is further reinforced by its photothermal effect. Furthermore, the enhanced ICD effect based on the dimer can completely eliminate the primary tumor on the seventh day of treatment and can also boost systemic antitumor immunity by generating immune memory, which is demonstrated by the superior antitumor therapeutic effects on both solid tumors and metastatic tumors when healing 4T1 tumor mouse models with poor immunogenicity.

A Polymeric Extracellular Matrix Nanoremodeler for Activatable Cancer Photo-Immunotherapy

Cancer immunotherapy has shown tremendous potential to train the intrinsic immune system against malignancy in the clinic. However, the extracellular matrix (ECM) in tumor microenvironment is a formidable barrier that not only restricts the penetration of therapeutic drugs but also prevents the infiltration of antitumor immune cells. We herein report a semiconducting polymer-based ECM nanoremodeler (SPNcb) to combine photodynamic antitumor activity with cancer-specific inhibition of collagen-crosslinking enzymes (lysyl oxidase (LOX) family) for activatable cancer photo-immunotherapy. SPNcb is self-assembled from an amphiphilic semiconducting polymer conjugated with a LOX inhibitor (β-aminopropionitrile, BAPN) via a cancer biomarker (cathepsin B, CatB)-cleavable segment. BAPN can be exclusively activated to inhibit LOX activity in the presence of the tumor-overexpressed CatB, thus blocking collagen crosslinking and decreasing ECM stiffness. Such an ECM nanoremodeler synergizes immunogenic phototherapy and checkpoint blockade immunotherapy to improve the tumor infiltration of cytotoxic T cells, inhibiting tumor growth and metastasis.

Attenuating Metabolic Competition of Tumor Cells for Favoring the Nutritional Demand of Immune Cells by a Branched Polymeric Drug Delivery System

Tumor cells are dominant in the nutritional competition in the tumor microenvironment, and their metabolic abnormalities often lead to microenvironmental acidosis and nutrient deprivation, thereby impairing the function of immune cells and diminishing the antitumor therapeutic effect. Herein, a branched polymeric conjugate and its efficacy in attenuating the metabolic competition of tumor cells are reported. Compared with the control nanoparticles prepared from its linear counterpart, the branched-conjugate-based nanoparticles can more efficiently accumulate in the tumor tissue and interfere with the metabolic processes of tumor cells to increase the concentration of essential nutrients and reduce the level of immunosuppressive metabolites in the TME, thus creating a favorable environment for infiltrated immune cells. Its combined treatment with an immune checkpoint inhibitor (ICI) achieves an enhanced antitumor effect. The work presents a promising approach for targeting metabolic competition in the TME to enhance the chemo-immunotherapeutic effect against cancers.