A Potent Strategy of Combinational Blow Toward Enhanced Cancer Chemo-Photodynamic Therapy via Sustainable GSH Elimination

Nanoplatform-based strategies for enhancing the lethality of current antitumor PDT

Photodynamic therapy (PDT) exhibits great application prospects in future clinical oncology due to its spatiotemporal controllability and good biosafety. However, the antitumor efficacy of PDT is seriously hindered by many factors, including tumor hypoxia, limited light penetration ability, and strong defense mechanisms of tumors. Considering that it is difficult to completely solve the first two problems, enhancing the lethality of antitumor PDT has become a good idea to extend its clinical application. Herein, we summarize the nanoplatform-involved strategies to effectively amplify the tumoricidal capability of current PDT and then discuss the present bottlenecks and prospects of the nanoplatform-based PDT sensitization strategies in tumor therapy. We hope this review will provide some references for others to design high-performance PDT nanoplatforms for tumor therapy.

Tumor-targeting polymer nanohybrids with amplified ROS generation for combined photodynamic and chemodynamic therapy

Reactive oxygen species (ROS) generating strategies have been widely adopted for cancer therapy, but therapeutic efficacies are often low due to the complicated tumor microenvironment. In this study, we present the development of tumor-targeting polymer nanohybrids that amplify ROS generation by combining photodynamic therapy (PDT) and chemodynamic therapy (CDT) for cancer treatment. Such polymer nanohybrids contained three main components: a semiconducting polymer (SP) that acted as the photosensitizer for PDT, manganese dioxide (MnO2) that acted as the catalyst for CDT, and transferrin that mediated tumor targeting via binding to transferrin receptors overexpressed on the surface of tumor cells. The formed nanohybrids (TSM) showed obviously enhanced accumulation efficacy in tumor sites because of their targeting ability. In tumor sites, TSM produced singlet oxygen (1O2) under near-infrared (NIR) laser irradiation and a hydroxyl radical (˙OH) via reacting with hydrogen peroxide (H2O2), which resulted in amplified generation of ROS to achieve PDT/CDT combinational therapy. The growth of subcutaneous 4T1 tumors was remarkably inhibited via TSM-mediated treatment. In addition, this therapeutic efficacy could suppress tumor metastasis in the liver and lungs. This study presents a targeting hybrid nanoplatform to combine different ROS generating strategies for effective cancer therapy.

GSH/pH Cascade-Responsive Nanoparticles Eliminate Methicillin-Resistant Staphylococcus aureus Biofilm via Synergistic Photo-Chemo Therapy

Bacterial biofilm infection threatens public health, and efficient treatment strategies are urgently required. Phototherapy is a potential candidate, but it is limited because of the off-targeting property, vulnerable activity, and normal tissue damage. Herein, cascade-responsive nanoparticles (NPs) with a synergistic effect of phototherapy and chemotherapy are proposed for targeted elimination of biofilms. The NPs are fabricated by encapsulating IR780 in a polycarbonate-based polymer that contains disulfide bonds in the main chain and a Schiff-base bond connecting vancomycin (Van) pendants in the side chain (denoted as SP-Van@IR780 NPs). SP-Van@IR780 NPs specifically target bacterial biofilms in vitro and in vivo by the mediation of Van pendants. Subsequently, SP-Van@IR780 NPs are decomposed into small size and achieve deep biofilm penetration due to the cleavage of disulfide bonds in the presence of GSH. Thereafter, Van is then detached from the NPs because the Schiff base bonds are broken at low pH when SP@IR780 NPs penetrate into the interior of biofilm. The released Van and IR780 exhibit a robust synergistic effect of chemotherapy and phototherapy, strongly eliminate the biofilm both in vitro and in vivo. Therefore, these biocompatible SP-Van@IR780 NPs provide a new outlook for the therapy of bacterial biofilm infection.

Optimized strategies of ROS-based nanodynamic therapies for tumor theranostics

Reactive oxygen species (ROS) play a crucial role in regulating the metabolism of tumor growth, metastasis, death and other biological processes. ROS-based nanodynamic therapies (NDTs) are becoming attractive due to non-invasive, low side effects and tumor-specific advantages. NDTs have rapidly developed into numerous branches, such as photodynamic therapy, chemodynamic therapy, sonodynamic therapy and so on. However, the complexity of the tumor microenvironment and the limitations of existing sensitizers have greatly restricted the therapeutic effects of NDTs, which heavily rely on ROS levels. To address the limitations of NDTs, various strategies have been developed to increase ROS yield, which is an urgent aspect for the positive development of NDTs. In this review, the nanodynamic potentiation strategies in terms of unique properties and universalities of NDTs are comprehensively outlined. We mainly summarize the current dilemmas faced by each NDT and the respective solutions. Meanwhile, the NDTs universalities-based potentiation strategies and NDTs-based combined treatments are elaborated. Finally, we conclude with a discussion of the key issues and challenges faced in the development and clinical transformation of NDTs.

Recent Advances of Platinum-Based Anticancer Complexes in Combinational Multimodal Therapy

Platinum drugs with manifest therapeutic effects are widely used, but their systemic toxicity and the drug resistance acquired by cancer cells limit their clinical applications. Thus, the exploration on appropriate methods and strategies to overcome the limitations of traditional platinum drugs becomes extremely necessary. Combination therapy of platinum drugs can inhibit tumor growth and metastasis in an additive or synergistic manner, and can potentially reduce the systemic toxicity of platinum drugs and overcome platinum-resistance. This review summarizes the various modalities and current progress in platinum-based combination therapy. The synthetic strategies and therapeutic effects of some platinum-based anticancer complexes in the combination of platinum drugs with gene editing, ROS-based therapy, thermal therapy, immunotherapy, biological modelling, photoactivation, supramolecular self-assembly and imaging modality are briefly described. Their potential challenges and prospects are also discussed. It is hoped that this review will inspire researchers to have more ideas for the future development of highly effective platinum-based anti-cancer complexes.

Ablation of Gap Junction Protein Improves the Efficiency of Nanozyme-Mediated Catalytic/Starvation/Mild-Temperature Photothermal Therapy

Reactive oxygen species (ROS)-mediated tumor catalytic therapy is typically hindered by gap junction proteins that form cell-to-cell channels to remove cytotoxic ROS, thereby protecting tumor cells from oxidative damage. In this work, a multifunctional nanozyme, FePGOGA, is designed and prepared by Fe(III)-mediated oxidative polymerization (FeP), followed by glucose oxidase (GOx) and GAP19 peptides co-loading through electrostatic and π-π interactions. The FePGOGA nanozyme exhibits excellent cascade peroxidase- and glutathione-oxidase-like activities that efficiently catalyze hydrogen peroxide conversion to hydroxyl radicals and convert reduced glutathione to oxidized glutathione disulfide. The loaded GOx starves the tumors and aggravates tumor oxidative stress through glucose decomposition, while GAP19 peptides block the hemichannels by inducing degradation of Cx43, thus increasing the accumulation of intracellular ROS, and decreasing the transport of intracellular glucose. Furthermore, the ROS reacts with primary amines of heat shock proteins to destroy their structure and function, enabling tumor photothermal therapy at the widely sought-after mild temperature (mildPTT, ≤45 °C). In vivo experiments demonstrate the significant antitumor effectof FePGOGA on cal27 xenograft tumors under near-infrared light irradiation. This study demonstrates the successful ablation of gap junction proteins to overcome resistance to ROS-mediated therapy, providing a regulator to suppress tumor self-preservation during tumor starvation, catalytic therapy, and mildPTT.

Development of "smart" drug delivery systems for chemo/PDT synergistic treatment

Although chemotherapy and photodynamic therapy (PDT) have been developed for fighting cancer, the complex and heterogeneous nature of tumors makes it difficult for a single therapy to completely inhibit tumor growth. In order to reduce multidrug resistance of cancer cells to chemotherapeutic drugs and overcome low PDT efficiency in the hypoxic tumor microenvironment (TME), chemo/PDT synergistic treatment has received much attention in recent years. Depending on the characteristic signals of TME, various drug delivery systems can be constructed to target tumors and improve the therapeutic efficacy and the pharmacokinetic profile of anticancer drugs. This review highlights the synergistic strategies, treatment protocols, and design of chemo/PDT co-therapy in recent years to explore its scope and limitations. Taking advantage of stimuli-responsive materials and active cancer-targeting agents, cancer-targeting synergistic therapy is presented and discussed, providing ideas and suggestions for the construction of chemo/PDT co-therapy "smart" nanocarriers.

Copperphosphotungstate Doped Polyanilines Nanorods for GSH-Depletion Enhanced Chemodynamic/NIR-II Photothermal Synergistic Therapy

Introduction

The high concentration of glutathione (GSH) and hydrogen peroxide (H₂O₂) levels within the tumor microenvironment (TME) are the major obstacle to induce the unsatisfactory anticancer treatment efficiency. The synergistic cancer therapy strategies of the combination the GSH depletion enhanced chemodynamic therapy (CDT) with photothermal therapy (PTT) have been proved to be the promising method to significantly improve the therapeutic efficacy.

Methods

The copperphosphotungstate was incorporated into polyanilines to design copperphosphotungstate doped polyaniline nanorods (CuPW@PANI Nanorods) via chemical oxidant polymerization of aniline. The low long-term toxicity and biocompatibility were evaluated. Both in vitro and in vivo experiments were carried out to confirm the GSH depletion enhanced CDT/NIR-II PTT synergistic therapy.

Results

CuPW@PANI Nanorods feature biosafety and biocompatibility, strong NIR-II absorbance, and high photothermal-conversion efficiency (45.14%) in NIR-II bio-window, making them highly applicable for photoacoustic imaging and NIR-II PTT. Moreover, CuPW@PANI Nanorods could consume endogenous GSH to disrupt redox homeostasis and perform a Fenton-like reaction with H₂O₂ to produce cytotoxic •OH for the enhanced CDT. Furthermore, NIR-II photothermal-induced local hyperthermia accelerates •OH generation to enhance CDT, which realizes high therapeutic efficacy in vivo.

Conclusion

This study provides a proof of concept of GSH-depletion augmented chemodynamic/NIR-II photothermal therapy.

Cyclodextrin-Derived ROS-Generating Nanomedicine with pH-Modulated Degradability to Enhance Tumor Ferroptosis Therapy and Chemotherapy

Nowadays, destruction of redox homeostasis to induce cancer cell death is an emerging anti-cancer strategy. Here, the authors utilized pH-sensitive acetalated β-cyclodextrin (Ac-β-CD) to efficiently deliver dihydroartemisinin (DHA) for tumor ferroptosis therapy and chemodynamic therapy in a synergistic manner. The Ac-β-CD-DHA based nanoparticles are coated by an iron-containing polyphenol network. In response to the tumor microenvironment, Fe²⁺ /Fe³⁺ can consume glutathione (GSH) and trigger the Fenton reaction in the presence of hydrogen peroxide (H₂ O₂ ), leading to the generation of lethal reactive oxygen species (ROS). Meanwhile, the OO bridge bonds of DHA are also disintegrated to enable ferroptosis of cancer cells. Their results demonstrate that these nanoparticles acted as a ROS generator to break the redox balance of cancer cells, showing an effective anticancer efficacy, which is different from traditional approaches.