A flowerlike FePt/MnO2/GOx-based cascade nanoreactor with sustainable O2 supply for synergistic starvation-chemodynamic anticancer therapy

Recent advances in chemodynamic nanotherapeutics to overcome multidrug resistance in cancers

Multidrug resistance (MDR) has become a major challenge in cancer therapy, it results in the failure of chemotherapy and anticancer drug development. Chemodynamic therapy (CDT), an emerging cancer treatment strategy, has been reported as a novel approach for cancer treatment characterized by low toxicity and minimal side effects. By generating robust cytotoxic hydroxyl radicals (·OH) via Fenton/Fenton-like reaction, CDT may cause cellular damage and oxidative stress-induced cell death. In recent years, many therapies based on CDT and/or combined with other treatment modalities are reported and exhibit exciting treatment efficacy in cancer treatment, such as photothermal therapy, photodynamic therapy, sonodynamic therapy, chemotherapy, starvation therapy and gas therapy etc. These combination therapies exhibit synergistic effects, significantly improving anticancer outcomes compared to CDT alone. Herein, we provide a comprehensive overview of CDT-based strategies in cancer treatment, highlighting developments of CDT and CDT-based combination strategies in tumor therapy, especially in overcoming MDR challenges. Finally, the opportunities and challenges of CDT and CDT-combination therapy in the clinical application are also addressed.

Tumor microenvironment-regulated nanoplatform for enhanced chemotherapy, cuproptosis and nonferrous ferroptosis combined cancer therapy

Therapeutic approaches combining various treatments have attracted intensive interests for tumor therapy. Nevertheless, these strategies still face many obstacles, such as overexpressed GSH and hypoxia, owing to the intricate tumor microenvironment (TME). Herein, a versatile nanoplatform, CeO2@CuO2@DOX-RSL3@HA (CCDRH), was initially constructed for promoting the antitumor efficiency via regulation of the TME. The CCDRH was prepared taking mixed valence CeO2 as the nanocarrier, followed by the attachment of CuO2 nanodots, DOX and RSL3 and the camouflaging of hyaluronic acid. The CuO2 could disassemble in the acidic TME to release Cu2+ and H2O2. The POD- and CAT-mimicking activities of CeO2 could convert H2O2 to ˙OH and O2, leading to the enhancement of chemo-chemodynamic therapy. Meanwhile, RSL3 could effectively suppress GPX4 expression, and the overloaded Cu2+ and Ce4+ could deplete excess GSH, resulting in an intensive accumulation of LPO and significant nonferrous ferroptosis. Additionally, Cu+ induces the oligomerization of lipoylated DLAT and downregulates iron-sulfur cluster proteins, resulting in potent cellular cuproptosis. The experimental results revealed that CCDRH exhibited high performance in tumor inhibition, which is attributed to the combined effect of enhanced chemotherapy, ferroptosis and cuproptosis. The study provides a new approach for improving anticancer efficiency via regulation of the TME.

Focused starvation of tumor cells using glucose oxidase: A comprehensive review

Starvation therapy targets the high metabolic demand of tumor cells. It primarily leans over the consumption of intracellular glucose and simultaneous blockade of alternative metabolic pathways. The strategy involves the use of glucose oxidase (GOx) for catalyzing the conversion of glucose into gluconic acid and hydrogen peroxide. Under these conditions, metabolic re-programming of tumor cells enables the utilization of substrates such as amino acids, fatty acids and lipids. This can be overcome by co-administration of chemo-, photo- and immuno-therapeutics together with glucose oxidase. Targeted delivery of glucose oxidase at tumor site can be enabled with the use of nanoformulations. In this review, we highlight that the outcomes of starvation therapy can be improved using rationally developed nano-formulations. It is possible to load synergistically acting bioactives in these formulations and deliver in site-specific manner and hence achieve the elimination of tumors cells with greater efficacy.

Recent advances in glucose oxidase-based nanocarriers for tumor targeting therapy

Glucose oxidase (GOx) can specifically catalyze the conversion of β-d-glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of oxygen, making it promising for tumor starvation therapy and oxidative therapy. However, GOx's immunogenicity, poor in vivo stability, short half-life, and potential systemic toxicity, limit its application in cancer therapy. Nanocarriers are capable of improving the pharmacological properties of therapeutic drugs (e.g. stability, circulating half-life, and tumor accumulation) and lower toxicity, hence resolving GOx issues and enhancing its efficacy. Although the application of targeted nanocarriers based on GOx has recently flourished, this field has not yet been reviewed and evaluated. Herein, we initially examined the mechanism of GOx-based nanocarriers for enhanced tumor therapy. Also, we present a comprehensive and up-to-date review that highlights GOx-based nanocarriers for tumor targeting therapy. This review expands on GOx-based nano-targeted combination therapies from both passive and active targeting perspectives, meanwhile, active targeting is further classified into ligand-mediated targeting and physical-mediated targeting. Furthermore, this review also emphasizes the present challenges and promising advancements.

Dual-Functional Nanoplatform Based on Bimetallic Metal-Organic Frameworks for Synergistic Starvation and Chemodynamic Therapy

Tumor microenvironment (TME)-responsive chemodynamic therapy (CDT) mediated by nanozymes has been extensively studied in oral squamous cell carcinoma. However, the low catalytic efficiency due to insufficient H₂O₂ in the TME is still a major challenge for its clinical translation. Herein, we present an antitumor nanoplatform based on a Mn-Co organometallic framework material (MnCoMOF), which shows peroxidase-like (POD-like) activity, loaded with glucose oxidase (GOx@MnCoMOF), demonstrating the ability of H₂O₂ self-supply and H₂O₂ conversion to toxic hydroxyl radicals. The encapsulated GOx efficiently catalyzes glucose into gluconic acid and H₂O₂ at the tumor site, which can cut off the energy supply to inhibit tumor growth and produce a large amount of H₂O₂ and acid to compensate for their lack in the tumor microenvironment. The POD-like activity of MnCoMOF can convert H₂O₂ into hydroxyl radicals and eliminate tumor cells. The nanoplatform exhibits enhanced tumor cell cytotoxicity in a high-glucose medium compared with a low-glucose medium, illustrating sufficient generation of H₂O₂ from glucose by GOx. The in vivo results indicate that GOx@MnCoMOF has excellent antitumor efficacy and can remodel the immune-suppressive tumor microenvironment. In conclusion, the GOx@MnCoMOF nanoplatform possesses dual enzymatic activities, i.e., POD-like and glucose oxidase, to achieve improved tumor-suppressive efficiency through synergistic starvation and chemodynamic therapy, thus providing a new strategy for the clinical treatment of oral cancer.

Multifunctional and multimodality theranostic nanomedicine for enhanced phototherapy

Photodynamic therapy (PDT) has attracted much attention in recent years for its favorable therapeutic efficacy in cancer therapy. However, PDT alone is insufficient to improve the therapeutic efficiency mainly due to the limited penetration depth of light, the insufficient O₂ supply in the hypoxic microenvironment, and the high level of reducing substances in cancer cells. To overcome these limitations, a multifunctional MnO₂ nanoparticle was constructed with honeycomb MnO₂ which was loaded with the photosensitizer Ce6 and modified with polydopamine on its surface (HMnO₂/C&P) to achieve efficient PDT/mild photothermal treatment (PTT) combination therapy. HMnO₂/C&P had high drug loading contents (11.2% Ce6) and can be responsive to the tumor microenvironment (TME), supply O₂ to alleviate the hypoxic microenvironment, and clear GSH to reduce the consumption of ROS, thus enhancing the PDT effect. The introduction of PDA can improve the stability of HMnO₂/C&P, and further give the ability of PTT to act as nanomedicine. The results of in vitro and in vivo experiments show that HMnO₂/C&P based PDT/mild PTT combination therapy has an excellent inhibitory effect on tumor growth. Meanwhile, HMnO₂/C&P can act as a fluorescence imaging reagent and a TME triggerable magnetic resonance imaging (MRI) contrast agent, thus having excellent multimodal self-tracking abilities. Collectively, this study provides a new perspective on the design of multifunctional theranostic nanomedicine to maximize the efficacy of cancer phototherapy.

A dual gate-controlled intelligent nanoreactor enables collaborative precise treatment for cancer nanotherapy

Recently, disulfiram (DSF), approved by the FDA as an anti-alcoholic drug, has been proved as an effective antitumor drug after chelating with Cu²⁺. To overcome the shortage of intracellular Cu²⁺, we have constructed a dual gate-controlled intelligent nanoreactor (HA-DSF@HCuS@FePtMn, HDHF) via the ingenious combination of hollow copper sulfide (HCuS) nanoparticles, DSF and FePtMn nanocrystals. HDHF has a NIR-actuated gate and enzyme-actuated gate that could be opened in the hyaluronidase-abundant tumor microenvironment with NIR laser irradiation to trigger drug (DSF/FePtMn) release and synergistic therapy. Moreover, the FePtMn nanocrystals could continuously release Fe²⁺, which could catalyze H₂O₂ into highly cytotoxic hydroxyl radicals (˙OH), triggering chemodynamic therapy (CDT). When exposed to NIR laser, HCuS could collapse and release Cu²⁺, which could immediately chelate with DSF, forming the effective anticancer drug (Cu(DTC)₂) and enabling DSF-based chemotherapy. More importantly, the efficient photothermal therapy (PTT) effect of HCuS could accelerate the FePtMn-based CDT and the release of Cu²⁺/DSF, improving tumor treatment efficiency. Thus, this study represents a distinctive paradigm of a dual gate-controlled intelligent nanoreactor enabled PTT-augmented DSF-based chemotherapy and FePtMn-based CDT for cancer nanotherapy.

Oncocyte Membrane-Camouflaged Multi-Stimuli-Responsive Nanohybrids for Synergistic Amplification of Tumor Oxidative Stresses and Photothermal Enhanced Cancer Therapy

The combination of various therapeutic modalities has received considerable attention for improving antitumor performance. Herein, an innovative nanohybrid, namely CaO₂@FePt-DOX@PDA@CM (CFDPM), was developed for synergistic chemotherapy/chemodynamic therapy/Ca²⁺ overloading-mediated amplification of tumor oxidative stress and photothermal enhanced cancer therapy. Camouflage of the 4T1 cell membrane enabled CFDPM to escape the immune surveillance and accumulate in the tumor tissue. Ca²⁺, released from CaO₂, could lead to mitochondrial dysfunction and facilitate the production of reactive oxygen species to amplify intracellular oxidative stress. Meanwhile, the increase of H₂O₂ concentration could enhance the efficiency of the chemodynamic therapy (CDT). Moreover, the hypoxic condition could be alleviated remarkably, which is attributed to the sufficient O₂ supply by CaO₂, resulting in the suppression of drug resistance and promotion of the chemotherapeutic effect. The nanohybrids involving Ca²⁺ overloading/CDT/chemotherapy could synergistically amplify the tumor oxidative stresses and remarkably aggravate the death of cancer cells. Significantly, the excellent photothermal conversion performance of CFDPM could further promote the tumoricidal effect. The in vitro and in vivo studies revealed that CFDPM could effectively advance the therapeutic efficiency via the cooperation of various therapeutic modalities to optimize their individual virtue, which would open a valuable avenue for effective cancer treatment.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

PDGFB targeting biodegradable FePt alloy assembly for MRI guided starvation-enhancing chemodynamic therapy of cancer

The application of chemodynamic therapy (CDT) for cancer is a serious challenge owing to the low efficiency of the Fenton catalyst and insufficient H₂O₂ expression in cells. Herein, we fabricated a PDGFB targeting, biodegradable FePt alloy assembly for magnetic resonance imaging (MRI)-guided chemotherapy and starving-enhanced chemodynamic therapy for cancer using PDGFB targeting, pH-sensitive liposome-coated FePt alloys, and GOx (pLFePt-GOx). We found that the Fenton-catalytic activity of FePt alloys was far stronger than that of traditional ultrasmall iron oxide nanoparticle (UION). Upon entry into cancer cells, pLFePt-GOx nanoliposomes degraded into many tiny FePt alloys and released GOx owing to the weakly acidic nature of the tumor microenvironment (TME). The released GOx-mediated glucose consumption not only caused a starvation status but also increased the level of cellular H₂O₂ and acidity, promoting Fenton reaction by FePt alloys and resulting in an increase in reactive oxygen species (ROS) accumulation in cells, which ultimately realized starving-enhanced chemodynamic process for killing tumor cells. The anticancer mechanism of pLFePt-GOx involved ROS-mediated apoptosis and ferroptosis, and glucose depletion-mediated starvation death. In the in vivo assay, the systemic delivery of pLFePt-GOx showed excellent antitumor activity with low biological toxicity and significantly enhanced T₂-weighted magnetic resonance imaging (MRI) signal of the tumor, indicating that pLFePt-GOx can serve as a highly efficient theranostic tool for cancer. This work thus describes an effective, novel multi-modal cancer theranostic system.

Disruption of dual homeostasis by a metal-organic framework nanoreactor for ferroptosis-based immunotherapy of tumor

Ferroptosis, a newfound non-apoptotic cell death pathway that is iron- and reactive oxygen species (ROS)-dependent, has shown a promise for tumor treatment. However, engineering ferroptosis inducers with sufficient hydrogen peroxide (H₂O₂) and iron supplying capacity remains a great challenge. To address this issue, herein, we report a powerful nanoreactor by modifying MnO₂, glucose oxidase, and polyethylene glycol on iron-based metal-organic framework nanoparticles for disrupting redox and iron metabolism homeostasis, directly providing the Fenton reaction-independent downstream ferroptosis for tumor therapy. By consuming glutathione and oxidizing glucose to increase the H₂O₂ level in cancer cells and downregulating ferroportin 1 to accumulate intracellular iron ions, the homeostasis disruptor could effectively enhance the ferroptosis. Subsequently, the ferroptosis cells release tumor immune-associated antigens, which combine with in situ injected aptamer-PD-L1 to further strengthen the tumor treatment efficiency. This work not only paves a way to enhance the efficacy of ferroptosis-based cancer therapy by associating intracellular redox homeostasis with the iron metabolism system in tumor cells but also offers an engineered nanoreactor as a promising mimetic antigen for activating immunotherapy.

Mitochondria-Targeted Degradable Nanocomposite Combined with Laser and Ultrasound for Synergistic Tumor Therapies

Although the development of safe and efficient cancer therapeutic agents is essential, this process remains challenging. In this study, a mitochondria-targeted degradable nanoplatform (PDA-MnO₂-IR780) for synergistic photothermal, photodynamic, and sonodynamic tumor treatment was investigated. PDA-MnO₂-IR780 exhibits superior photothermal properties owing to the integration of polydopamine, MnO₂, and IR780. IR780, a photosensitizer and sonosensitizer, was used for photodynamic therapy and sonodynamic therapy. When PDA-MnO₂-IR780 was delivered to the tumor site, MnO₂ was decomposed by hydrogen peroxide, producing Mn²⁺ and oxygen. Meanwhile, alleviating tumor hypoxia promoted the production of reactive oxygen species during photodynamic therapy and sonodynamic therapy. Moreover, large amounts of reactive oxygen species could reduce the expression of heat shock proteins and increase the heat sensitivity of tumor cells, thereby improving the photothermal treatment effect. In turn, hyperthermia caused by photothermal therapy accelerated the production of reactive oxygen species in photodynamic therapy. IR780 selectively accumulation in mitochondria also promoted tumor apoptosis. In this system, the mutual promotion of photothermal therapy and photodynamic therapy/sonodynamic therapy had an enhanced therapeutic effect. Moreover, the responsive degradable characteristic of PDA-MnO₂-IR780 in the tumor microenvironment ensured excellent biological safety. These results reveal a great potential of PDA-MnO₂-IR780 for safe and highly-efficiency synergistic therapy for cancer.

Dual-Targeted Fe₃O₄@MnO₂ Nanoflowers for Magnetic Resonance Imaging-Guided Photothermal-Enhanced Chemodynamic/Chemotherapy for Tumor

The construction of high-efficiency tumor theranostic platform will be of great interest in the treatment of cancer patients; however, significant challenges are associated with developing such a platform. In this study, we developed high-efficiency nanotheranostic agent based on ferroferric oxide, manganese dioxide, hyaluronic acid and doxorubicin (FMDH-D NPs) for dual targeting and imaging guided synergetic photothermal-enhanced chemodynamic/chemotherapy for cancer, which improved the specific uptake of drugs at tumor site by the dual action of CD44 ligand hyaluronic acid and magnetic nanoparticles guided by magnetic force. Under the acidic microenvironment of cancer cells, FMDH-D could be decomposed into Mn²⁺ and Fe²⁺ to generate •OH radicals by triggering a Fenton-like reaction and responsively releasing doxorubicin to kill cancer cells. Meanwhile, alleviating tumor hypoxia improved the efficacy of chemotherapy in tumors. The photothermal properties of FMDH generated high temperatures, which further accelerated the generation of reactive oxygen species, and enhanced effects of chemodynamic therapy. Furthermore, FMDH-D NPs proved to be excellent T₁/T₂-weighted magnetic resonance imaging contrast agents for monitoring the tumor location. These results confirmed the considerable potential of FMDH-D NPs in a highly efficient synergistic therapy platform for cancer treatment.

Novel monodisperse FePt nanocomposites for T2-weighted magnetic resonance imaging: biomedical theranostics applications

Given the high incidence and mortality of cancer, current research is focused on designing efficient diagnostic methods. At present, clinical diagnoses are made based on X-ray, computed tomography, magnetic resonance imaging (MRI), ultrasound, and fiber optic endoscopy. MRI is a powerful diagnostic tool because it is non-invasive, has a high spatial resolution, uses non-ionizing radiation, and has good soft-tissue contrast. However, the long relaxation time of water protons may result in the inability to distinguish different tissues. To overcome this drawback of MRI, magnetic resonance contrast agents can enhance the contrast, improve the sensitivity of MRI-based diagnoses, increase the success rate of surgery, and reduce tumor recurrence. This review focuses on using iron-platinum (FePt) nanoparticles (NPs) in T2-weighted MRI to detect tumor location based on dark-field changes. In addition, existing methods for optimizing and improving FePt NPs are reviewed, and the MRI applications of FePt NPs are discussed. FePT NPs are expected to strengthen MRI resolution, thereby helping to inhibit tumor development.