Glutathione-Responsive Nanoparticles of Camptothecin Prodrug for Cancer Therapy

Polyoxometalate-Containing Nanocomposite Hydrogels for Cascade-Catalytic and Photothermal Dually Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) has emerged as a transformative paradigm in the realm of reactive oxygen species (ROS)-mediated cancer therapies. However, the lack of endogenous hydrogen peroxide (H2O2) in tumors and the low catalytic efficiency of traditional Fenton catalysts limit the therapeutic effect of CDT. Herein, an injectable nanocomposite hydrogel (HA-DOPA/W-POM/1-S-S-PEG@GOx) based on the hyaluronic acid-dopamine (HA-DOPA) matrix is designed to deliver tungsten-based polyoxometalates (W-POM) and peptide nanomicelles (1-S-S-PEG@GOx) for achieving cascade-catalytic and photothermal dually enhanced CDT. Upon tumor cell uptake, 1-S-S-PEG@GOx specifically responds to endogenous glutathione and disassembles to release glucose oxidase (GOx), which catalyzes the oxidation of glucose to produce H2O2. On the one hand, W-POM functions as peroxidase-like nanozymes to convert H2O2 into a hydroxyl radical (·OH) under the aid of GOx, enhancing the efficacy of CDT through cascade-catalytic reactions (i.e., glucose to H2O2 to ·OH). On the other hand, W-POM acts as a photothermal therapy agent, generating mild heat under near-infrared laser irradiation to achieve photothermal-enhanced CDT. This cascade-catalytic and photothermal dually enhanced CDT triggers an intracellular ROS storm, leading to apoptosis and ferroptosis of tumor cells. Importantly, in situ administration of HA-DOPA/W-POM/1-S-S-PEG@GOx alongside laser irradiation showcases enhanced antitumor efficacy and satisfactory biocompatibility in vivo, which holds great potential for the development of functional nanomedicine toward targeted tumor therapy.

SN-38-indoximod conjugate: carrier free nano-prodrug for cancer therapy

BACKGROUND

The integration of immunotherapy alongside chemotherapy represents a crucial approach in the treatment of cancer. Herein we report the SN-38-indoximod conjugate nano-prodrug to address the difficulties encountered by individuals. In this prodrug, SN-38 is connected to indoximod through a specific disulfide linker, which enables the release of the components in response to the tumor microenvironment characterized by elevated levels of glutathione, thereby facilitating programmed chemoimmunotherapy.

RESULTS

SN-38-indoximod conjugate was synthesized and fabricated to nano-prodrug by reprecipitation method. It showed comparable anti-cancer activity against A549 cells than SN-38 (IC50 = 0.24 ± 0.01 µM) with IC50 value 0.32 ± 0.04 µM. It inhibited 90% A549 cell at very lower concentration (IC90 = 6.07 ± 0.41 µM) as compared with SN-38 (IC90 = 24.60 ± 1.24 µM) and mixture of SN-38: indoximod (1:1, IC90 >30 µM). The nano-prodrug showed better size distribution profile and dispersion stability contains nanoparticles in effective size range (80-160 nm) required for the EPR effect.

CONCLUSION

This research offers valuable insights into the advancement of conjugate nano-prodrugs exhibiting synergistic pharmacological effects, while also presenting novel opportunities for the design of prodrug molecules capable of releasing drugs in response to diverse triggers.

Thermosensitive liposome-encapsulated gold nanocages for photothermal-modulated drug release and synergistic photothermal therapy

Delivery nanosystems have been widely developed to improve the efficacy of chemotherapy. However, their performance regarding the non-specific leakage of drugs remained unsatisfactory. Herein, gold nanocages (AuNCs) were used as carriers and thermo-sensitive liposome (TSL) as a protective shell to design a camptothecin (CPT)-loaded delivery nanosystem (AuNCs/CPT@TSL) for photothermal-modulated drug release. This approach effectively avoided the non-specific leakage of CPT and enabled the combination of photothermal therapy (PTT) and chemotherapy. In the simulated tumor microenvironment (pH = 5.5), the TSL shell prevented CPT leakage at 37 °C, with a release rate of only 11.4%. However, the release rate of CPT greatly increased to 85.4% when the temperature was elevated to 45 °C. The photothermal conversion efficiency of AuNCs/CPT@TSL reached up to 46.1%. At an incubation temperature of 37 °C, the cell survival rate decreased to 43.6% in AuNCs/CPT but remained above 90% in AuNCs/CPT@TSL, demonstrating the protective effect of the TSL shell. Under the combination of PTT and chemotherapy, cell viability drastically decreased to 10.9%, and the tumors completely disappeared, confirming the safe and reliable antitumor effect of AuNCs/CPT@TSL.

Demystifying the management of cancer through smart nano-biomedicine via regulation of reactive oxygen species

Advancements in therapeutic strategies and combinatorial approaches for cancer management have led to the majority of cancers in the initial stages to be regarded as treatable and curable. However, certain high-grade cancers in the initial stages are still regarded as chronic and difficult to manage, requiring novel therapeutic strategies. In this era of targeted and precision therapy, novel strategies for targeted delivery of drug and synergistic therapies, integrating nanotherapeutics, polymeric materials, and modulation of the tumor microenvironment are being developed. One such strategy is the study and utilization of smart-nano biomedicine, which refers to stimuli-responsive polymeric materials integrated with the anti-cancer drug that can modulate the reactive oxygen species (ROS) in the tumor microenvironment or can be ROS responsive for the mitigation as well as management of various cancers. The article explores in detail the ROS, its types, and sources; the antioxidant system, including scavengers and their role in cancer; the ROS-responsive targeted polymeric materials, including synergistic therapies for the treatment of cancer via modulating the ROS in the tumor microenvironment, involving therapeutic strategies promoting cancer cell death; and the current landscape and future prospects.

Spatiotemporal-controllable ROS-responsive camptothecin nano-bomb for chemo/photo/immunotherapy in triple-negative breast cancer

Chemotherapy is still one of the major approaches in triple-negative breast cancer (TNBC) treatment. The development of new formulations for classic chemotherapeutic drugs remains interests in studies. Camptothecin (CPT) is powerful antitumor agents in TNBC treatment though its clinic applications are limited by its low water solubility and systemic toxicity. To prepare a spatiotemporal controllable CPT nano-formulation, we construct a ROS-responsive self-assembly nanoparticle by combining hydrophobic CPT and hydrophilic 5-floxuridine (FUDR). A ROS-sensitive thioketal (TK) linker is used to prepare CPT-TK-FUDR (CTF). Next, we introduced IR780-based phototherapy to elicit massive ROS regeneration due to the endogenous ROS is not sufficient. IR780 is modified with hyaluronic acid (HA) to prepare HA-modified IR780 (HAIR) for its biocompatibility and tumor targeting ability improvement. CTF and HAIR self-assemble to form an attractive nano-bomb (HAIR/CTF NPs). HA accurately guides the NPs to tumor sites via HA-receptor recognition on tumor cells. After internalization, overexpressed intracellular HAase in tumor cells disassembles the NPs to free the contents. Due to the presence of IR780 molecules, the scheduled irradiation of 808 nm laser induces massive reactive oxygen species (ROS) generation, which further result in the cleavage of TK linker for free drugs release. Additionally, ROS-mediated photodynamic therapy (PDT) and near-infrared laser-mediated photothermal therapy (PTT) synergistically worked to eradicate tumor cells. Then immunogenic cell death (ICD) was evoked by CPT and phototherapy to amplify antitumor immunity, thereby achieving primary and abscopal tumor inhibition. In conclusion, the HAIR/CTF nano-bomb realized spatiotemporal controllable drug release, exciting tumor eradication and attractive anti-metastasis efficacy via combination chemo/photo/immunotherapy, offering a valuable reference for the re-development of classic drug in future clinical practice.

Endosomal pH, Redox Dual-Sensitive Prodrug Micelles Based on Hyaluronic Acid for Intracellular Camptothecin Delivery and Active Tumor Targeting in Cancer Therapy

Background: CPT is a pentacyclic monoterpene alkaloid with a wide spectrum of antitumor activity. Its clinical application is restricted due to poor water solubility, instability, and high toxicity. We developed a new kind of multifunctional micelles to improve its solubility, reduce the side effecs, and obtain enhanced antitumor effects. Methods: We constructed HA-CPT nano-self-assembly prodrug micelles, which combined the advantages of pH-sensitivity, redox-sensitivity, and active targeting ability to CD44 receptor-overexpressing cancer cells. To synthesize dual sensitive HA-CPT conjugates, CPT was conjugated with HA by pH-sensitive histidine (His) and redox-sensitive 3,3'-dithiodipropionic acid (DTPA). In vitro, we studied the cellular uptake and antitumor effect for tumor cell lines. In vivo, we explored the bio-distribution and antitumor effects of the micelles in HCT 116 tumor bearing nude mice. Results: The dual-sensitive and active targeting HA-His-ss-CPT micelles was proved to be highly efficient in CPT delivery by the in vitro cellular uptake study. The HA-His-ss-CPT micelles escaped from endosomes of tumor cells within 4 h after cellular uptake due to the proton sponge effect of the conjugating His and then quickly released CPT in the cytosol by glutathione (GSH). In mice, HA-His-ss-CPT micelles displayed efficient tumor accumulation and conspicuous inhibition of tumor growth. Conclusions: The novel, dual-sensitive, active targeting nano-prodrug micelles exhibited high efficiency in drug delivery and cancer therapy. This "all in one" drug delivery system can be realized in an ingenious structure and avoid intricate synthesis. This construction strategy can illume the design of nanocarriers responding to endogenous stimuli in tumors.

A fibroblast activation protein α-activatable nanoagent co-delivering diethyldithiocarbamate and copper for tumor therapy and imaging

Disulfiram (DSF), an FDA-approved drug for treating alcoholism, has been verified with Cu2+-dependent anticancer activity by forming Cu(DTC)2, the complex of one of its metabolites diethyldithiocarbamate (DTC) and Cu2+. Nevertheless, the antitumor effect is limited by insufficient Cu(DTC)2 formation in suit and off-target system toxicity. Herein, we developed a fibroblast activation protein α (FAPα) activatable nanoagent (HfD-HID-Cu) for co-delivery of DTC polymeric prodrug and exogenous Cu2+ to achieve enhanced cancer-specific therapy and activatable in situ fluorescence imaging meanwhile. HfD-HID-Cu was simply constructed through the co-assembly of the DTC polymeric prodrug (HA-fap-DTC) and the copper-loaded IR808-conjugated polymer (HA-IR-DPA-Cu), which could serve as the "OFF-to-ON" switch for chemotherapy and fluorescence. With the high expression of FAPα in tumor tissues, HA-fap-DTC could be activated specifically to release DTC, while maintaining inactive in normal tissues. The liberated DTC within tumor tissues could contend for Cu2+ from HA-IR-DPA-Cu, resulting in the formation of highly cytotoxic Cu(DTC)2in situ for chemotherapy, concomitant with the fluorescence recovery of cyanine dye for tumor imaging. This work provides an effective strategy for co-delivery of DTC prodrug and Cu2+ for tumor theranostic with improved selectivity and minimal side effects. STATEMENT OF SIGNIFICANCE: DSF-based antitumor therapy is highly dependent on Cu2+. However, the non-synchronous distribution of DSF/DTC and Cu2+ in tumor tissues attenuates the antitumor efficacy. The insufficient Cu(DTC)2 formation in suit and off-target distribution greatly limit the anti-tumor application. This study provides a nanoagent for co-delivery of DTC polymeric prodrug and Cu2+ by simple co-assembly to achieve their synchronous tumor distribution. It can be selectively activated by FAPα, forming cytotoxic Cu(DTC)2in suit for tumor-specific chemotherapy and reducing the systemic toxicity. In addition to chemotherapy, the nanoagent can emit fluorescence under the sequential triggering of FAPα and released DTC for tumor imaging. Overall, this study renders a promising strategy for improved Cu(DTC)2-based antitumor therapy and imaging.

G-Quadruplex-Programmed Versatile Nanorobot Combined with Chemotherapy and Gene Therapy for Synergistic Targeted Therapy

Developing synergistic targeted therapeutics to improve treatment efficacy while reducing side effects has proven promising for anticancer therapies, but how to conveniently modulate multidrug cooperation remains a challenge. Here, a novel synergistic strategy using a G-quadruplex-programmed versatile nanorobot (G4VN) containing two subunits of DNAzyme (DzG4) and ligand-drug conjugates (LDCs) is proposed to precisely target tumors and then execute both gene silencing and chemotherapy. As the core module of this nanorobot, a well-designed G4 responding to a high level of K+ in tumor microenvironment smartly kills three birds with one stone, which makes two TfR aptamers proximate to improve their efficiency of targeting tumor cells, and in situ activates a split 10-23 DNAzyme to downregulate target mRNA expression, meanwhile promotes the cell uptake of a GSH-responsive LDCs to enhance drug efficacy. Such a design enables a potently synergistic anticancer therapy with low side effects in vivo, showing great promise for broad applications in precision disease treatment.

Stimulus-Responsive Nano-Prodrug Strategies for Cancer Therapy: A Focus on Camptothecin Delivery

Camptothecin (CPT) is a highly cytotoxic molecule with excellent antitumor activity against various cancers. However, its clinical application is severely limited by poor water solubility, easy inactivation, and severe toxicity. Structural modifications and nanoformulations represent two crucial avenues for camptothecin's development. However, the potential for further structural modifications is limited, and camptothecin nanoparticles fabricated via physical loading have the drawbacks of low drug loading and leakage. Prodrug-based CPT nanoformulations have shown unique advantages, including increased drug loading, reduced burst release, improved bioavailability, and minimal toxic side effects. Stimulus-responsive CPT nano-prodrugs that respond to various endogenous or exogenous stimuli by introducing various activatable linkers to achieve spatiotemporally responsive drug release at the tumor site. This review comprehensively summarizes the latest research advances in stimulus-responsive CPT nano-prodrugs, including preparation strategies, responsive release mechanisms, and their applications in cancer therapy. Special focus is placed on the release mechanisms and characteristics of various stimulus-responsive CPT nano-prodrugs and their application in cancer treatment. Furthermore, clinical applications of CPT prodrugs are discussed. Finally, challenges and future research directions for CPT nano-prodrugs are discussed. This review to be valuable to readers engaged in prodrug research is expected.

Maleimide functionalized polycaprolactone micelles for glutathione quenching and doxorubicin delivery

High glutathione production is known to be one of the defense mechanisms by which many cancer cells survive elevated oxidative stress. By explicitly targeting glutathione in these cancer cells and diminishing its levels, oxidative stress can be intensified, ultimately triggering apoptosis or programmed cell death. Herein, we developed a novel approach by creating maleimide-functionalized polycaprolactone polymers, specifically using 2,3-diiodomaleimide functionality to reduce the level of glutathione in cancer cells. Polycaprolactone was chosen to conjugate the 2,3-diiodomaleimide functionality due to its biodegradable and biocompatible properties. The amphiphilic block copolymer was synthesized using PEG as a macroinitiator to make corresponding polymeric micelles. The resulting 2,3-diiodomaleimide-conjugated polycaprolactone micelles effectively quenched glutathione, even at low concentrations (0.01 mg mL-1). Furthermore, we loaded these micelles with the anticancer drug doxorubicin (DOX), which exhibited pH-dependent drug release. We obtained a loading capacity (LC) of 3.5% for the micelles, one of the highest LC reported among functional PCL-based micelles. Moreover, the enhanced LC doesn't affect their release profile. Cytotoxicity experiments demonstrated that empty and DOX-loaded micelles inhibited cancer cell growth, with the DOX-loaded micelles displaying the highest cytotoxicity. The ability of the polymer to quench intracellular GSH was also confirmed. This approach of attaching maleimide to polycaprolactone polymers shows promise in depleting elevated glutathione levels in cancer cells, potentially improving cancer treatment efficacy.

Prediction of immunotherapy response of bladder cancer with a pyroptosis-related signature indicating tumor immune microenvironment

Background

Although prognostic models based on pyroptosis-related genes (PRGs) have been constructed in bladder cancer (BLCA), the comprehensive impact of these genes on tumor microenvironment (TME) and immunotherapeutic response has yet to be investigated.

Methods

Based on expression profiles of 52 PRGs, we utilized the unsupervised clustering algorithm to identify PRGs subtypes and ssGSEA to quantify immune cells and hallmark pathways. Moreover, we screened feature genes of distinct PRGs subtypes and validated the associations with immune infiltrations in tissue using the multiplex immunofluorescence. Univariate, LASSO, and multivariate Cox regression analyses were employed to construct the scoring scheme.

Results

Four PRGs clusters were identified, samples in cluster C1 were infiltrated with more immune cells than those in others, implying a favorable response to immunotherapy. While the cluster C2, which shows an extremely low level of most immune cells, do not respond to immunotherapy. CXCL9/CXCL10 and SPINK1/DHSR2 were identified as feature genes of cluster C1 and C2, and the specimen with high CXCL9/CXCL10 was characterized by more CD8 + T cells, macrophages and less Tregs. Based on differentially expressed genes (DEGs) among PRGs subtypes, a predictive model (termed as PRGs score) including five genes (CACNA1D, PTK2B, APOL6, CDK6, ANXA2) was built. Survival probability of patients with low-PRGs score was significantly higher than those with high-PRGs score. Moreover, patients with low-PRGs score were more likely to benefit from anti-PD1/PD-L1 regimens.

Conclusion

PRGs are closely associated with TME and oncogenic pathways. PRGs score is a promising indicator for predicting clinical outcome and immunotherapy response.

Bioorthogonal In Situ Polymerization of Dendritic Agents for Hijacking Lysosomes and Enhancing Antigen Presentation in Cancer Cells

A low-generation lysine dendrimer, SPr-G2, responds to intracellular glutathione to initiate bioorthogonal in situ polymerization, resulting in the formation of large assemblies in mouse breast cancer cells. The intracellular large assemblies of SPr-G2 can interact with lysosomes to induce lysosome expansion and enhance lysosomal membrane permeabilization, leading to major histocompatibility complex class I upregulation on tumor cell surfaces and ultimately tumor cell death. Moreover, the use of the SPr-G2 dendrimer to conjugate the chemotherapeutic drug, camptothecin (CPT), can boost the therapeutic potency of CPT. Excellent antitumor effects in vitro and in vivo are obtained from the combinational treatment of the SPr-G2 dendrimer and CPT. This combinational effect also enhances antitumor immunity through promoting activation of cytotoxic T cells in tumor tissues and maturation of dendritic cells. This study can shed new light on the development of peptide dendritic agents for cancer therapy.

Glutathione-depleting Liposome Adjuvant for Augmenting the Efficacy of a Glutathione Covalent Inhibitor Oridonin for Acute Myeloid Leukemia Therapy

BACKGROUND

Discrepancies in the utilization of reactive oxygen species (ROS) between cancer cells and their normal counterparts constitute a pivotal juncture for the precise treatment of cancer, delineating a noteworthy trajectory in the field of targeted therapies. This phenomenon is particularly conspicuous in the domain of nano-drug precision treatment. Despite substantial strides in employing nanoparticles to disrupt ROS for cancer therapy, current strategies continue to grapple with challenges pertaining to efficacy and specificity. One of the primary hurdles lies in the elevated levels of intracellular glutathione (GSH). Presently, predominant methods to mitigate intracellular GSH involve inhibiting its synthesis or promoting GSH efflux. However, a conspicuous gap remains in the absence of a strategy capable of directly and efficiently clearing GSH.

METHODS

We initially elucidated the chemical mechanism underpinning oridonin, a diminutive pharmacological agent demonstrated to perturb reactive oxygen species, through its covalent interaction with glutathione. Subsequently, we employed the incorporation of maleimide-liposomes, renowned for their capacity to disrupt the ROS delivery system, to ameliorate the drug's water solubility and pharmacokinetics, thereby enhancing its ROS-disruptive efficacy. In a pursuit to further refine the targeting for acute myeloid leukemia (AML), we harnessed the maleic imide and thiol reaction mechanism, facilitating the coupling of Toll-like receptor 2 (TLR2) peptides to the liposomes' surface via maleic imide. This strategic approach offers a novel method for the precise removal of GSH, and its enhancement endeavors are directed towards fortifying the precision and efficacy of the drug's impact on AML targets.

RESULTS

We demonstrated that this peptide-liposome-small molecule machinery targets AML and consequently induces cell apoptosis both in vitro and in vivo through three disparate mechanisms: (I) Oridonin, as a Michael acceptor molecule, inhibits GSH function through covalent bonding, triggering an initial imbalance of oxidative stress. (II) Maleimide further induces GSH exhaustion, aggravating redox imbalance as a complementary augment with oridonin. (III) Peptide targets TLR2, enhances the directivity and enrichment of oridonin within AML cells.

CONCLUSION

The rationally designed nanocomplex provides a ROS drug enhancement and targeted delivery platform, representing a potential solution by disrupting redox balance for AML therapy.

Selenization of Small Molecule Drugs: A New Player on the Board

There is an urgent need to develop safer and more effective modalities for the treatment of a wide range of pathologies due to the increasing rates of drug resistance, undesired side effects, poor clinical outcomes, etc. Throughout the years, selenium (Se) has attracted a great deal of attention due to its important role in human health. Besides, a growing body of work has unveiled that the inclusion of Se motifs into a great number of molecules is a promising strategy for obtaining novel therapeutic agents. In the current Perspective, we have gathered the most recent literature related to the incorporation of different Se moieties into the scaffolds of a wide range of known drugs and their feasible pharmaceutical applications. In addition, we highlight different representative examples as well as provide our perspective on Se drugs and the possible future directions, promises, opportunities, and challenges of this ground-breaking area of research.

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Platinum Prodrug Nanoparticles with COX-2 Inhibition Amplify Pyroptosis for Enhanced Chemotherapy and Immune Activation of Pancreatic Cancer

Pyroptosis, an emerging mechanism of programmed cell death, holds great potential to trigger a robust antitumor immune response. Platinum-based chemotherapeutic agents can induce pyroptosis via caspase-3 activation. However, these agents also enhance cyclooxygenase-2 (COX-2) expression in tumor tissues, leading to drug resistance and immune evasion in pancreatic cancer and significantly limiting the effectiveness of chemotherapy-induced pyroptosis. Here, an amphiphilic polymer (denoted as PHDT-Pt-In) containing both indomethacin (In, a COX-2 inhibitor) and platinum(IV) prodrug (Pt(IV)) is developed, which is responsive to glutathione (GSH). This polymer self-assemble into nanoparticles (denoted as Pt-In NP) that can disintegrate in cancer cells due to the GSH responsiveness, releasing In to inhibit the COX-2 expression, hence overcoming the chemoresistance and amplifying cisplatin-induced pyroptosis. In a pancreatic cancer mouse model, Pt-In NP significantly inhibit tumor growth and elicit both innate and adaptive immune responses. Moreover, when combined with anti-programmed death ligand (α-PD-L1) treatment, Pt-In NP demonstrate the ability to completely suppress metastatic tumors, transforming "cold tumors" into "hot tumors". Overall, the sustained release of Pt(IV) and In from Pt-In NP amplifies platinum-drug-induced pyroptosis to elicit long-term immune responses, hence presenting a generalizable strategy for pancreatic cancer.

Cell Death Pathway Regulation by Functional Nanomedicines for Robust Antitumor Immunity

Cancer immunotherapy has become a mainstream cancer treatment over traditional therapeutic modes. Cancer cells can undergo programmed cell death including ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis which are find to have intrinsic relationships with host antitumor immune response. However, direct use of cell death inducers or regulators may bring about severe side effects that can also be rapidly excreted and degraded with low therapeutic efficacy. Nanomaterials are able to carry them for long circulation time, high tumor accumulation and controlled release to achieve satisfactory therapeutic effect. Nowadays, a large number of studies have focused on nanomedicines-based strategies through modulating cell death modalities to potentiate antitumor immunity. Herein, immune cell types and their function are first summarized, and state-of-the-art research progresses in nanomedicines mediated cell death pathways (e.g., ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis) with immune response provocation are highlighted. Subsequently, the conclusion and outlook of potential research focus are discussed.

Targeting DNA Damage and Repair Machinery via Delivering WEE1 Inhibitor and Platinum (IV) Prodrugs to Stimulate STING Pathway for Maximizing Chemo-Immunotherapy in Bladder Cancer

Both cisplatin-based chemotherapy and immune checkpoint blockers (ICBs)-based immunotherapy are the first-line treatments for patients with advanced bladder cancer. Cancer cells can develop resistance to cisplatin through extensive DNA repair, while a low response rate to ICBs is mostly due to the presence of an immunosuppressive microenvironment and low PD-L1 expression. Herein, a glutathione (GSH)-responsive nanoparticle (NP2) loaded with cisplatin prodrug (Pt (IV)) and WEE1 inhibitor (MK1775) is designed. NP2 can be triggered by GSH in cancer cells, and the released MK1775 can inhibit the activity of WEE1 protein, which ultimately increases DNA damage by cisplatin. Genome-wide RNA sequencing first reveals that NP2 can inhibit DNA repair machinery by interfering with the cell cycle and significantly activate the stimulator of interferon genes pathway. Tumor growth is significantly inhibited by NP2 in vivo. As innate and adaptive immune responses are stimulated, the immunosuppressive microenvironment is modified, and the "immune cold tumor" is transformed into an "immune hot tumor". In addition, NP2 can upregulate PD-L1 expression in tumor cells, thereby increasing the response rate of PD-L1 monoclonal antibody (αPD-L1) and eliciting long-term immune responses in both primary and metastatic tumors.

Camptothecin-based prodrug nanomedicines for cancer therapy

Camptothecin (CPT) is a cytotoxic alkaloid that attenuates the replication of cancer cells via blocking DNA topoisomerase 1. Despite its encouraging and wide-spectrum antitumour activity, its application is significantly restricted owing to its instability, low solubility, significant toxicity, and acquired tumour cell resistance. This has resulted in the development of many CPT-based therapeutic agents, especially CPT-based nanomedicines, with improved pharmacokinetic and pharmacodynamic profiles. Specifically, smart CPT-based prodrug nanomedicines with stimuli-responsive release capacity have been extensively explored owing to the advantages such as high drug loading, improved stability, and decreased potential toxicity caused by the carrier materials in comparison with normal nanodrugs and traditional delivery systems. In this review, the potential strategies and applications of CPT-based nanoprodrugs for enhanced CPT delivery toward cancer cells are summarized. We appraise in detail the chemical structures and release mechanisms of these nanoprodrugs and guide materials chemists to develop more powerful nanomedicines that have real clinical therapeutic capacities.

Stimuli-Responsive Prodrug Chemistries for Cancer Therapy

Prodrugs are pharmacologically inactive, chemically modified derivatives of active drugs, which, following in vivo administration, are converted to the parent drugs through chemical or enzymatic cleavage. The prodrug approach holds tremendous potential to create the enhanced version of an existing pharmacological agent and leverage those improvements to augment the drug molecules' bioavailability, targeting ability, therapeutic efficacy, safety, and marketability. Especially in cancer therapy, prodrug application has received substantial attention. A prodrug can effectively broaden the therapeutic window of its parent drug by enhancing its release at targeted tumor sites while reducing its access to healthy cells. The spatiotemporally controlled release can be achieved by manipulating the chemical, physical, or biological stimuli present at the targeted tumor site. The critical strategy comprises drug-carrier linkages that respond to physiological or biochemical stimuli in the tumor milieu to yield the active drug form. This review will focus on the recent advancements in the development of various fluorophore-drug conjugates that are widely used for real-time monitoring of drug delivery. The use of different stimuli-cleavable linkers and the mechanisms of linker cleavage will be discussed. Finally, the review will conclude with a critical discussion of the prospects and challenges that might impede the future development of such prodrugs.

Development of a novel sialic acid-conjugated camptothecin prodrug for enhanced cancer chemotherapy

Camptothecin (CPT) is an attractive natural drug for cancer chemotherapy. However, the poor water solubility, non-targeting feature, and adverse side effects of CPT are significant obstacles to developing an effective anticancer drug. Here, for the first time, 9-thiol-sialic acid (9-SH-Sia) is coupled to CPT by forming a disulfide releasable carbonate linkage, resulting in a novel CPT prodrug (CPT-ss-Sia) that self-assembles into nanostructures in an aqueous solution. Strikingly, CPT-ss-Sia exhibited excellent in vitro properties, including enhanced water solubility, glutathione (GSH)-triggered CPT release, and increased E-lactone ring stability. Furthermore, CPT-ss-Sia had good cancer cell-killing ability comparable to CPT. Intravenous administration of CPT-ss-Sia significantly inhibited the growth of multiple types of tumors. Histological analysis showed that CPT-ss-Sia treatment significantly reduced lesions in tumor-bearing mice compared to CPT treatment. Notably, CPT-ss-Sia treatment did not adversely affect the body weight of the mice. This is the first report of the 9-SH-Sia conjugate-based prodrug. Overall, CPT-ss-Sia has broad clinical application prospects.

Tumor permeable self-delivery nanodrug targeting mitochondria for enhanced chemotherapy

Drug self-delivery systems (DSDSs) have been extensively exploited to enhance drug loading capacity and avoid excipient-related toxicity issues. However, deficient tumor targeting, inferior tumor permeability, prominent burst release, and nonspecific subcellular distribution remain major obstacles. Herein, we reported a ROS-responsive amphiphilic prodrug (CPT-S-NO) synthesized by the conjugation of zwitterionic tertiary amine-oxide (TAO) moiety and hydrophobic camptothecin (CPT) through a thioether linkage, which formed a nanoparticulate DSDS in an aqueous solution. CPT-S-NO, compared with CPT-11 and the water-soluble TAO-modified CPT prodrug (CPT-NO), exhibited prolonged blood circulation, enhanced tumor accumulation, deep tumor penetration, efficient mitochondrial targeting, and ROS-activated drug release to induce mitochondrial dysfunction, corporately conducing to the superior antitumor efficacy in vivo. This TAO decoration strategy promises potential applications in designing multipotent DSDSs for various drugs.

Smart Targeted Delivery Systems for Enhancing Antitumor Therapy of Active Ingredients in Traditional Chinese Medicine

As a therapeutic tool inherited for thousands of years, traditional Chinese medicine (TCM) exhibits superiority in tumor therapy. The antitumor active components of TCM not only have multi-target treatment modes but can also synergistically interfere with tumor growth compared to traditional chemotherapeutics. However, most antitumor active components of TCM have the characteristics of poor solubility, high toxicity, and side effects, which are often limited in clinical application. In recent years, delivering the antitumor active components of TCM by nanosystems has been a promising field. The advantages of nano-delivery systems include improved water solubility, targeting efficiency, enhanced stability in vivo, and controlled release drugs, which can achieve higher drug-delivery efficiency and bioavailability. According to the method of drug loading on nanocarriers, nano-delivery systems can be categorized into two types, including physically encapsulated nanoplatforms and chemically coupled drug-delivery platforms. In this review, two nano-delivery approaches are considered, namely physical encapsulation and chemical coupling, both commonly used to deliver antitumor active components of TCM, and we summarized the advantages and limitations of different types of nano-delivery systems. Meanwhile, the clinical applications and potential toxicity of nano-delivery systems and the future development and challenges of these nano-delivery systems are also discussed, aiming to lay the foundation for the development and practical application of nano-delivery systems of TCM in clinical settings.

Cuproptosis Induced by ROS Responsive Nanoparticles with Elesclomol and Copper Combined with αPD-L1 for Enhanced Cancer Immunotherapy

Cuproptosis is a new cell death that depends on copper (Cu) ionophores to transport Cu into cancer cells, which induces cell death. However, existing Cu ionophores are small molecules with a short blood half-life making it hard to transport enough Cu into cancer cells. Herein, a reactive oxygen species (ROS)-sensitive polymer (PHPM) is designed, which is used to co-encapsulate elesclomol (ES) and Cu to form nanoparticles (NP@ESCu). After entering cancer cells, ES and Cu, triggered by excessive intracellular ROS, are readily released. ES and Cu work in a concerted way to not only kill cancer cells by cuproptosis, but also induce immune responses. In vitro, the ability of NP@ESCu to efficiently transport Cu and induce cuproptosis is investigated. In addition, the change in the transcriptomes of cancer cells treated with NP@ESCu is explored by RNA-Seq. In vivo, NP@ESCu is found to induce cuproptosis in the mice model with subcutaneous bladder cancer, reprograming the tumor microenvironment. Additionally, NP@ESCu is further combined with anti-programmed cell death protein ligand-1 antibody (αPD-L1). This study provides the first report of combining nanomedicine that can induce cuproptosis with αPD-L1 for enhanced cancer therapy, thereby providing a novel strategy for future cancer therapy.

Self-Propelled Enzymatic Nanomotors from Prodrug-Skeletal Zeolitic Imidazolate Frameworks for Boosting Multimodel Cancer Therapy Efficiency

Self-propelled nanomotors, which can autonomous propelled by harnessing others type of energy, have shown tremendous potential as drug delivery systems for cancer therapy. However, it remains challenging for nanomotors in tumor theranostics because of their structural complexity and deficient therapeutic model. Herein, glucose-fueled enzymatic nanomotors (GC6@cPt ZIFs) are developed through encapsulation of glucose oxidase (GOx), catalase (CAT), and chlorin e6 (Ce6) using cisplatin-skeletal zeolitic imidazolate frameworks (cPt ZIFs) for synergetic photochemotherapy. The GC6@cPt ZIFs nanomotors can produce O₂ through enzymatic cascade reactions for propelling the self-propulsion. Trans-well chamber and multicellular tumor spheroids experiments demonstrate the deep penetration and high accumulation of GC6@cPt nanomotors. Importantly, the glucose-fueled nanomotor can release the chemotherapeutic cPt and generate reactive oxygen species under laser irradiation, and simultaneously consume intratumoral over-expressed glutathione. Mechanistically, such processes can inhibit cancer cell energy and destroy intratumoral redox balance to synergistically damage DNA and induce tumor cell apoptosis. Collectively, this work demonstrates that the self-propelled prodrug-skeleton nanomotors with oxidative stress activation can highlight a robust therapeutic capability of oxidants amplification and glutathione depletion to boost the synergetic cancer therapy efficiency.