Photothermal MnO2 nanoparticles boost chemo-photothermal therapy-induced immunogenic cell death in tumor immunotherapy

Nano-Proteolysis Targeting Chimeras (Nano-PROTACs) in Cancer Therapy

Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules that have the capability to induce specific protein degradation. While playing a revolutionary role in effectively degrading the protein of interest (POI), PROTACs encounter certain limitations that impede their clinical translation. These limitations encompass off-target effects, inadequate cell membrane permeability, and the hook effect. The advent of nanotechnology presents a promising avenue to surmount the challenges associated with conventional PROTACs. The utilization of nano-proteolysis targeting chimeras (nano-PROTACs) holds the potential to enhance specific tissue accumulation, augment membrane permeability, and enable controlled release. Consequently, this approach has the capacity to significantly enhance the controllable degradation of target proteins. Additionally, they enable a synergistic effect by combining with other therapeutic strategies. This review comprehensively summarizes the structural basis, advantages, and limitations of PROTACs. Furthermore, it highlights the latest advancements in nanosystems engineered for delivering PROTACs, as well as the development of nano-sized PROTACs employing nanocarriers as linkers. Moreover, it delves into the underlying principles of nanotechnology tailored specifically for PROTACs, alongside the current prospects of clinical research. In conclusion, the integration of nanotechnology into PROTACs harbors vast potential in enhancing the anti-tumor treatment response and expediting clinical translation.

Nanoparticle-mediated immunogenic cell death for cancer immunotherapy

The field of cancer therapy is witnessing the emergence of immunotherapy, an innovative approach that activates the body own immune system to combat cancer. Immunogenic cell death (ICD) has emerged as a prominent research focus in the field of cancer immunotherapy, attracting significant attention in recent years. The activation of ICD can induce the release of damage-associated molecular patterns (DAMPs), such as calreticulin (CRT), adenosine triphosphate (ATP), high mobility group box protein 1 (HMGB1), and heat shock proteins (HSP). Subsequently, this process promotes the maturation of innate immune cells, including dendritic cells (DCs), thereby triggering a T cell-mediated anti-tumor immune response. The activation of the ICD ultimately leads to the development of long-lasting immune responses against tumors. Studies have demonstrated that partial therapeutic approaches, such as chemotherapy with doxorubicin, specific forms of radiotherapy, and phototherapy, can induce the generation of ICD. The main focus of this article is to discuss and review the therapeutic methods triggered by nanoparticles for ICD, while briefly outlining their anti-tumor mechanism. The objective is to provide a comprehensive reference for the widespread application of ICD.

Manganese-based nanomaterials promote synergistic photo-immunotherapy: green synthesis, underlying mechanisms, and multiple applications

Single phototherapy and immunotherapy have individually made great achievements in tumor treatment. However, monotherapy has difficulty in balancing accuracy and efficiency. Combining phototherapy with immunotherapy can realize the growth inhibition of distal metastatic tumors and enable the remote monitoring of tumor treatment. The development of nanomaterials with photo-responsiveness and anti-tumor immunity activation ability is crucial for achieving photo-immunotherapy. As immune adjuvants, photosensitizers and photothermal agents, manganese-based nanoparticles (Mn-based NPs) have become a research hotspot owing to their multiple ways of anti-tumor immunity regulation, photothermal conversion and multimodal imaging. However, systematic studies on the synergistic photo-immunotherapy applications of Mn-based NPs are still limited; especially, the green synthesis and mechanism of Mn-based NPs applied in immunotherapy are rarely comprehensively discussed. In this review, the synthesis strategies and function of Mn-based NPs in immunotherapy are first introduced. Next, the different mechanisms and leading applications of Mn-based NPs in immunotherapy are reviewed. In addition, the advantages of Mn-based NPs in synergistic photo-immunotherapy are highlighted. Finally, the challenges and research focus of Mn-based NPs in combination therapy are discussed, which might provide guidance for future personalized cancer therapy.

Nanomaterial Delivery Vehicles for the Development of Neoantigen Tumor Vaccines for Personalized Treatment

Tumor vaccines have been considered a promising therapeutic approach for treating cancer in recent years. With the development of sequencing technologies, tumor vaccines based on neoantigens or genomes specifically expressed in tumor cells, mainly in the form of peptides, nucleic acids, and dendritic cells, are beginning to receive widespread attention. Therefore, in this review, we have introduced different forms of neoantigen vaccines and discussed the development of these vaccines in treating cancer. Furthermore, neoantigen vaccines are influenced by factors such as antigen stability, weak immunogenicity, and biosafety in addition to sequencing technology. Hence, the biological nanomaterials, polymeric nanomaterials, inorganic nanomaterials, etc., used as vaccine carriers are principally summarized here, which may contribute to the design of neoantigen vaccines for improved stability and better efficacy.

Manganese Dioxide Nanoplatform with a Hollow Rhombic Dodecahedron Morphology for Drug Delivery

Manganese dioxide (MnO2) is considered as a promising drug carrier material suitable for the tumor microenvironment while lacking conducive structures for drug loading. Herein, we construct a MnO2 nanoplatform with a hollow rhombic dodecahedral morphology for drug delivery. In this work, we obtained zeolitic imidazolate framework nanoparticles (ZIF-90 NPs) via a coordination reaction. Furthermore, the drug-loading nanoparticles (ZIF-90/DOX NPs) were obtained by Schiff's base reaction and then selected as a sacrificial template to obtain the hollow nanoplatforms (ZIF-90@MnO2 NPs). Moreover, the photothermal effect and multiresponsive drug release behaviors were revealed by loading the photothermal agent IR-820 and the anticancer drug doxorubicin hydrochloride (DOX). Our study demonstrates that the ZIF-90@MnO2 NPs loaded with photosensitizers exhibited excellent photothermal conversion performance. Benefiting from the hollow structure and redox activity, remarkable drug loading and release performances of ZIF-90@MnO2 NPs were achieved. It is shown that ZIF-90@MnO2 NPs achieved a satisfactory drug-loading efficiency (up to ca. 69.7%) for DOX. More promisingly, the ZIF-90@MnO2 NPs exhibited significant glutathione (GSH)/pH-responsive drug release and degradation performances. Overall, this work highlights the potential of controlled drug release of nanocarriers and offers unique insights into the design of nanocarriers with hollow structures.

Amplifying "eat me signal" by immunogenic cell death for potentiating cancer immunotherapy

Immunogenic cell death (ICD) is a unique mode of cell death, which can release immunogenic damage-associated molecular patterns (DAMPs) and tumor-associated antigens to trigger long-term protective antitumor immune responses. Thus, amplifying "eat me signal" during tumor ICD cascade is critical for cancer immunotherapy. Some therapies (radiotherapy, photodynamic therapy (PDT), photothermal therapy (PTT), etc.) and inducers (chemotherapeutic agents, etc.) have enabled to initiate and/or facilitate ICD and activate antitumor immune responses. Recently, nanostructure-based drug delivery systems have been synthesized for inducing ICD through combining treatment of chemotherapeutic agents, photosensitizers for PDT, photothermal transformation agents for PTT, radiosensitizers for radiotherapy, etc., which can release loaded agents at an appropriate dosage in the designated place at the appropriate time, contributing to higher efficiency and lower toxicity. Also, immunotherapeutic agents in combination with nanostructure-based drug delivery systems can produce synergetic antitumor effects, thus potentiating immunotherapy. Overall, our review outlines the emerging ICD inducers, and nanostructure drug delivery systems loading diverse agents to evoke ICD through chemoradiotherapy, PDT, and PTT or combining immunotherapeutic agents. Moreover, we discuss the prospects and challenges of harnessing ICD induction-based immunotherapy, and highlight the significance of multidisciplinary and interprofessional collaboration to promote the optimal translation of this treatment strategy.

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.

PD-L1 Blockade Peptide-Modified Polymeric Nanoparticles for Oxygen-Independent-Based Hypoxic Tumor Photo/Thermodynamic Immunotherapy

Distant metastasis of malignant tumors is considered to be the main culprit for the failure of current antitumor treatments. Conventional single treatments often exhibit limited efficacy in inhibiting tumor metastasis. Therefore, there is a growing interest in developing collaborative antitumor strategies based on photothermal therapy (PTT) and free-radical-generated photodynamic therapy (PDT), especially utilizing oxygen-independent nanoplatforms, to address this challenge. Such antitumor strategies can enhance the therapeutic outcomes by ensuring the cytotoxicity of free radicals even in the hypoxic tumor microenvironment, thereby improving the effective suppression of primary tumors. Additionally, these approaches can stimulate the production of tumor-associated antigens and amplify the immunogenic cell death (ICD) effects, potentially feasible for enhancing the therapeutic outcomes of immunotherapy. Herein, we fabricated a functional nanosystem that co-loads IR780 and 2,2'-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride (AIPH) to realize PTT-triggered thermodynamic combination therapy via the oxygen-independent pathway for the elimination of primary tumors. Furthermore, the nanocomposites were surface-decorated with a predesigned complex peptide (PLGVRGC-anti-PD-L1 peptide, MMP-sensitive), which facilitated the immunotherapy targeting distant tumors. Through the specific recognition of matrix metalloproteinase (MMP), the sensitive segment on the obtained aNC@IR780A was cleaved. As a result, the freed anti-PD-L1 peptide effectively blocked immune checkpoints, leading to the infiltration and activation of T cells (CTLs). This nanosystem was proven to be effective at inhibiting both primary tumors and distant tumors, providing a promising combination strategy for tumor PTT/TDT/immunotherapy.

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.

Bimetallic infinite coordination nanopolymers via phototherapy and STING activation for eliciting robust antitumor immunity

Phototherapy can trigger immunogenic cell death of tumors in situ, whereas it is virtually impossible to eradicate the tumor due to the intrinsic resistance and inefficient anti-tumor immunity. To overcome these limitations, novel bimetallic infinite coordination nanopolymers (TA-Fe/Mn-OVA@MB NPs) were synthesized using model antigen ovalbumin (OVA) as a template to assemble tannic acid (TA) and bi-metal, supplemented with methylene blue (MB) surface absorption. The formulated TA-Fe/Mn-OVA@MB NPs possess excellent photothermal and photodynamic therapy (PTT/PDT) performance, which is adequate to destroy tumor cells by physical and chemical attack. Especially, these TA-Fe/Mn-OVA@MB NPs are capability of promoting the dendritic cells (DCs) maturation and antigen presentation via manganese-mediated cGAS-STING pathway activation, finally activating cytotoxicity T lymphocyte and promoting memory T lymphocyte differentiation in the peripheral lymphoid organs. In conclusion, this research offers a versatile metal-polyphenol nanoplatform to integrate functional metals and therapeutic molecule for topical phototherapy and robust anti-tumor immune activation.

Hypoxia-ameliorated photothermal manganese dioxide nanoplatform for reversing doxorubicin resistance

Drug resistance is a huge hurdle in tumor therapy. Tumor hypoxia contributes to chemotherapy resistance by inducing the hypoxia-inducible factor-1α (HIF-1α) pathway. To reduce tumor hypoxia, novel approaches have been devised, providing significant importance to reverse therapeutic resistance and improve the effectiveness of antitumor therapies. Herein, the nanosystem of bovine serum albumin (BSA)-templated manganese dioxide (MnO₂) nanoparticles (BSA/MnO₂ NPs) loaded with doxorubicin (DOX) (DOX-BSA/MnO₂ NPs) developed in our previous report was further explored for their physicochemical properties and capacity to reverse DOX resistance because of their excellent photothermal and tumor microenvironment (TME) response effects. The DOX-BSA/MnO₂ NPs showed good biocompatibility and hemocompatibility. Meanwhile, DOX-BSA/MnO₂ NPs could greatly affect DOX pharmacokinetic properties, with prolonged circulation time and reduced cardiotoxicity, besides enhancing accumulation at tumor sites. DOX-BSA/MnO₂ NPs can interact with H₂O₂ and H⁺ in TME to form oxygen and exhibit excellent photothermal effect to further alleviate hypoxia due to MnO₂, reversing DOX resistance by down-regulating HIF-1α expression and significantly improving the antitumor efficiency in DOX-resistant human breast carcinoma cell line (MCF-7/ADR) tumor model. The hypoxia-ameliorated photothermal MnO₂ platform is a promising strategy for revering DOX resistance.

Biomineralized Manganese Oxide Nanoparticles Synergistically Relieve Tumor Hypoxia and Activate Immune Response with Radiotherapy in Non-Small Cell Lung Cancer

Radiotherapy (RT) is currently considered as an essential treatment for non-small cell lung cancer (NSCLC); it can induce cell death directly and indirectly via promoting systemic immune responses. However, there still exist obstacles that affect the efficacy of RT such as tumor hypoxia and immunosuppressive tumor microenvironment (TME). Herein, we report that the biomineralized manganese oxide nanoparticles (Bio-MnO₂ NPs) prepared by mild enzymatic reaction could be a promising candidate to synergistically enhance RT and RT-induced immune responses by relieving tumor hypoxia and activating cGAS-STING pathway. Bio-MnO₂ NPs could convert endogenic H₂O₂ to O₂ and catalyze the generation of reactive oxygen species so as to sensitize the radiosensitivity of NSCLC cells. Meanwhile, the release of Mn²⁺ into the TME significantly enhanced the cGAS-STING activity to activate radio-immune responses, boosting immunogenic cell death and increasing cytotoxic T cell infiltration. Collectively, this work presents the great promise of TME reversal with Bio-MnO₂ NPs to collaborate RT-induced antitumor immune responses in NSCLC.