Encapsulation of Platinum Prodrugs into PC7A Polymeric Nanoparticles Combined with Immune Checkpoint Inhibitors for Therapeutically Enhanced Multimodal Chemotherapy and Immunotherapy by Activation of the STING Pathway

Smart Organic-Inorganic Copolymer Nanoparticles Distinguish Between Microglia and Cancer Cells for Synergistic Immunotherapy in Glioma

The stimulator of interferon genes (STING) pathway has emerged as a new immunotherapy strategy with potent local stimulation specificity, showing promising potential to counteract the immunosuppression in glioma. Herein, a tumor microenvironment (TME) responsive nanoagonists are developed based on an organic-inorganic copolymer composed of the polymer PC6AB coupled with manganous phosphate ionic oligomers (MnP). The degradation of nanoagonists into PC6AB and MnP in the acidic TME enables spatiotemporal control of their delivery to tumor cells and immune cells, respectively. PC6AB with membranolytic activity selectively interacts with tumor cell membranes to induce immunogenic cell death, while manganese metal can activate the STING pathway in immune cells and trigger downstream immunostimulatory signals. Nanoagonists can stimulate robust antitumor immunity after local injection into the brain extracellular space (ECS), showing significant therapeutic efficacy in mouse glioma. Nanoagonists can achieve spatiotemporal orchestration of STING activation in response to TME and enhance immune response against "cold" solid tumors, providing a promising approach for clinical immunotherapy.

Nanoparticle-Based Strategies to Enhance the Efficacy of STING Activators in Cancer Immunotherapy

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway plays a critical role in triggering innate and adaptive immune responses through type I interferon activation and immune cell recruitment, holding significant promise for cancer therapy. While STING activators targeting this pathway have been developed, their clinical application is hindered by challenges such as poor membrane permeability, rapid degradation, suboptimal pharmacokinetics, off-target biodistribution, and toxicity. Nanoparticle-based delivery systems offer a promising solution by enhancing the stability, circulation time, tumor accumulation, and intracellular release of STING activators. Furthermore, combining nanoparticle-delivered STING activators with radiotherapy, chemotherapy, phototherapy, and other immunotherapies enables synergistic antitumor effects through multimodal mechanisms, addressing resistance to monotherapies and reducing risks of recurrence and metastasis. This review outlines the immunomodulatory mechanisms of the cGAS-STING pathway, surveys current STING-targeted activators, and comprehensively discusses recent advances in nanoparticle-mediated delivery strategies for STING activation. Additionally, we explore combinatorial approaches that integrate STING-targeted nanotherapies with conventional and emerging treatments. Finally, we highlight the current status, prospects, and challenges of nanoparticle-based STING activation for cancer immunotherapy.

Stimuli-Responsive Nodal Dual-Drug Polymer Nanoparticles for Cancer Therapy

Background

Polymeric drug delivery systems (DDSs) have gained significant attention in cancer therapy. However, these systems often respond to a single biological stimulus in tumor tissues or cells, limiting their effectiveness. While multi-sensitive DDSs improve therapeutic precision, their complex synthesis involving multi-step modifications remains challenging. Developing functionally integrated and simplified multiple stimuli-responsive DDSs is crucial to addressing tumor diversity and enhancing treatment efficacy.

Methods and Results

Here, we develop a dual-sensitive nodal dual-drug polymer nanoparticle (DDPoly NP) system for cancer therapy. This system combines a platinum(IV) prodrug (Cisplatin(IV)) with Demehylcantharidin (DMC) to create a dual-drug molecule (DDM). Then DDM is conjugated with methoxypolyethylene glycol (MPEG), forming a nodal dual-drug polymer (DDPoly). The amphiphilic polymer is capable of self-assembling into nanoparticles (DDPoly NPs) when in aqueous solution. The drug release experiments displayed that lower pH and reductive conditions simulating tumor microenvironment promoted the release of Cisplatin and DMC. Cytotoxicity studies demonstrated that DDPoly NPs exhibited superior anti-cancer activity compared to the single-drug system (SDPoly NPs). The IC50 values of DDPoly NPs against A549 cells (15.37 μM) and HeLa cells (17.05 μM) were significantly lower than those observed for SDPoly NPs, which were 40.48 μM for A549 cells and 38.11 μM for HeLa cells, respectively.

Conclusion

The study developed dual stimuli-responsive DDPoly NPs based on acid- and reduction-sensitive DDM, enabling tumor-specific activation without additional responsive components. DDPoly NPs triggered Pt(II) release via reduction and generated DMC through acid hydrolysis. The synergistic effect of DDPoly NPs lies in that DMC could inhibit the expression of serine/threonine protein phosphatase 2A (PP2A) and further elevate the expression of hyper-phosphorylated Akt (pAKt), thus blocking DNA repair to enhance Pt(II)-induced apoptosis. DDPoly NPs showed enhanced anti-cancer efficacy against cancer cells compared to SDPoly NPs, highlighting its potential for nanomedicine development.

Chemoimmunotherapy synergism: mechanisms and clinical applications

Chemoimmunotherapy, combining chemotherapy and immunotherapy, has emerged as a promising strategy for treating various cancers. This approach leverages the complementary mechanisms of both modalities to enhance tumor eradication. Recent advances have shed new light on the synergistic interactions between chemotherapy and immunotherapy, revealing complex mechanisms that contribute to improved clinical outcomes. Chemotherapy induces immunogenic cell death, releasing tumor antigens and damage-associated molecular patterns (DAMPs) that stimulate immune responses. It also modulates the tumor microenvironment, enhancing immune cell infiltration and reducing immunosuppressive elements. Concurrently, immunotherapy, particularly immune checkpoint inhibitors, activates the immune system to more effectively target and destroy cancer cells. Clinical evidence demonstrates significant benefits of chemoimmunotherapy in various cancers, including non-small-cell lung cancer, triple-negative breast cancer, and melanoma. Recent trials, such as KEYNOTE- 189 and IMpassion130, have shown improved overall survival and progression-free survival compared to chemotherapy alone. Emerging biomarkers, including tumor mutational burden, Programmed Death Ligand- 1 (PD-L1) expression, and immune cell infiltration patterns, are refining patient selection and response prediction. Novel strategies, such as nanoparticle-based drug delivery systems and personalized medicine approaches, are being explored to optimize chemoimmunotherapy combinations. However, challenges remain, including managing treatment-related toxicities, determining optimal dosing and sequencing, and addressing potential resistance mechanisms. Ongoing research focuses on elucidating the complex interplay between chemotherapy-induced immunomodulation and immune checkpoint inhibition to further improve treatment efficacy and patient outcomes. This review provides a comprehensive update on the mechanisms, clinical applications, and future directions of chemoimmunotherapy, highlighting its potential to revolutionize cancer treatment strategies. Clinical trial number: not applicable.

Unleashing the Potential of Metal Ions in cGAS-STING Activation: Advancing Nanomaterial-Based Tumor Immunotherapy

Immunotherapy is a critical modality in cancer treatment with diverse activation pathways. In recent years, the stimulator of interferon genes (STING) signaling pathway has exhibited significant potential in tumor immunotherapy. This pathway exerts notable antitumor effects by activating innate and adaptive immunity and regulating the tumor immune microenvironment. Various metal ions have been identified as effective activators of the STING pathway and, through the design and synthesis of nanodelivery platforms, have been applied in immunotherapy as well as in combination therapies, such as chemotherapy, chemodynamic therapy, photodynamic therapy, and cancer vaccines. Metal nanomaterials showcase unique advantages in immunotherapy; however, there are still aspects that require optimization. This review systematically examines existing metal-based nanomaterials, elaborates on the mechanisms by which different metal ions activate the STING pathway, and discusses their application models in tumor combination therapies. We also provide a comparative analysis of the advantages of metal nanomaterials over other treatment methods. Our exploration highlights the broad application prospects of metal nanomaterials in cancer treatment, offering new insights and directions for the advancement of tumor immunotherapy.

Advanced Polymeric Nanoparticles for Cancer Immunotherapy: Materials Engineering, Immunotherapeutic Mechanism and Clinical Translation

Cancer immunotherapy, which leverages immune system components to treat malignancies, has emerged as a cornerstone of contemporary therapeutic strategies. Yet, critical concerns about the efficacy and safety of cancer immunotherapies remain formidable. Nanotechnology, especially polymeric nanoparticles (PNPs), offers unparalleled flexibility in manipulation-from the chemical composition and physical properties to the precision control of nanoassemblies. PNPs provide an optimal platform to amplify the potency and minimize systematic toxicity in a broad spectrum of immunotherapeutic modalities. In this comprehensive review, the basics of polymer chemistry, and state-of-the-art designs of PNPs from a physicochemical standpoint for cancer immunotherapy, encompassing therapeutic cancer vaccines, in situ vaccination, adoptive T-cell therapies, tumor-infiltrating immune cell-targeted therapies, therapeutic antibodies, and cytokine therapies are delineated. Each immunotherapy necessitates distinctively tailored design strategies in polymeric nanoplatforms. The extensive applications of PNPs, and investigation of their mechanisms of action for enhanced efficacy are particularly focused on. The safety profiles of PNPs and clinical research progress are discussed. Additionally, forthcoming developments and emergent trends of polymeric nano-immunotherapeutics poised to transform cancer treatment paradigms into clinics are explored.

AIEgen-self-assembled nanoparticles with anti-PD-L1 antibody functionalization realize enhanced synergistic photodynamic therapy and immunotherapy against malignant melanoma

Immune checkpoint inhibitors (ICIs) become integral in clinical practice, yet their application in cancer therapy is constrained by low overall response rates and the primary resistance of cancers to ICIs. Herein, this study proposes aggregation-induced emission (AIE)-based nanoparticles (NPs) for a more effective and synergistic approach combining immunotherapy and photodynamic therapy (PDT) to achieve higher responses than anti-PD-L1 monotherapy. The TBP@aPD-L1 NPs are constructed by functionalizing azide group-modified TBP-2 (TBP-N3) with anti-PD-L1 antibodies via the DBCO-S-S-PEG2000-COOH linker. The anti-PD-L1 target the tumor cells and promote the TBP-N3 accumulation in tumors for enhanced PDT. Notably, the TBP-N3, featuring aggregation-induced emission, boosts reactive oxygen species (ROS) generation through both type I and type II processes for enhanced PDT. The TBP@aPD-L1-mediated PDT induces more powerful effects of direct tumor cell-killing and further elicits effective immunogenic cell death (ICD), which exerts anti-tumor immunity by activating T cells for ICI treatment and reshapes the tumor immune microenvironment (TIME), thereby enhancing the efficacy of PD-L1 blockade of anti-PD-L1. Consequently, TBP@aPD-L1 NPs demonstrated significantly enhanced inhibition of tumor growth in the mouse model of malignant melanoma (MM). Our NPs act as a facile and effective drug delivery platform for enhanced immunotherapy combined with enhanced PDT in treating MM.

Stromal Reprogramming Optimizes KRAS-Specific Chemotherapy Inducing Antitumor Immunity in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a clinically challenging cancer and is often characterized with rich stroma and mutated KRAS, which determines the tumor microenvironment (TME) and therapy response. Turning immunologically "cold" PDAC into "hot" is an unmet need to improve the therapeutic outcome. Herein, we propose a programmable strategy by sequential delivery of pirfenidone (PFD) and nanoengineered KRAS specific inhibitor (AMG510) and gemcitabine (GEM) liposomes. PFD could achieve precise reduction of the extracellular matrix (ECM) by reprogramming pancreatic stellate cells (PSCs). Subsequently, targeting the KRAS-directed oncogenic signaling pathway effectively inhibited tumor proliferation and migration, which sensitized a chemotherapeutic drug and promoted immunogenic cell death (ICD). In preclinical mouse models of PDAC, PFD mediated stromal modulation enhanced the deep penetration of nanoparticles and improved their subsequent performance in tumor growth inhibition. The molecular mechanisms elucidated that the stroma intervention and KRAS signal pathway regulation reshaped the immunosuppression of PDAC and optimized cytotoxic T-cell-mediated antitumor immunity with sustained antitumor memory. Overall, our study provides a practical strategy with clinical translational promise for immunologically cold tumor PDAC treatment.

Recent advances in nanoadjuvant-triggered STING activation for enhanced cancer immunotherapy

The development of effective cancer treatments is a popular in contemporary medical research. Immunotherapy, the fourth most common cancer treatment method, relies on activating autoimmune function to eradicate tumors and exhibits advantages such as a good curative effect and few side effects. In recent years, tumor vaccines that activate the stimulator of interferon genes (STING) pathway are being actively researched in the field of immunotherapy; however, their application is still limited because of the rapid clearance rate of tumor-related lymph nodes and low efficiency of antigen presentation. The rise of nanomedicine has provided new opportunities for solving these problems. By preparing materials with adjuvant effects nanoparticles, the small size of nanoparticles can be exploited to enable the entry of vaccines into tumor-related lymph nodes to accurately deliver STING agonists and activate the immune response. Based on this, this paper reviews various types of nano-adjuvants based on metals, platinum chemotherapy drugs, camptothecin derivatives, deoxyribonucleic acid, etc. and highlights the transformation prospects of these nano-adjuvants in tumor vaccines to provide a reference for promoting the development of nano-medicine and tumor vaccinology.

Nanomaterial-based cancer immunotherapy: enhancing treatment strategies

Cancer immunotherapy has emerged as a pivotal approach for treating various types of cancer, incorporating strategies such as chimeric antigen receptor T-cell (CAR-T) therapy, immune checkpoint blockade therapy, neoantigen peptides, mRNA vaccines, and small molecule modulators. However, the clinical efficacy of these therapies is frequently constrained by significant adverse effects and limited therapeutic outcomes. In recent years, the integration of nanotechnology into cancer immunotherapy has gained considerable attention, showcasing notable advantages in drug delivery, targeted accumulation, controlled release, and localized administration. This review focuses on nanomaterial-based immunotherapeutic strategies, particularly the development and application of nanocarriers such as liposomes, lipid nanoparticles, polymeric nanoparticles, and self-assembling scaffolds. We examine how these strategies can enhance the efficacy of cancer immunotherapy while minimizing adverse effects and analyze their potential for clinical translation.

Hybrid nanoparticle-mediated simultaneous ROS scavenging and STING activation improve the antitumor immunity of in situ vaccines

In situ vaccine (ISV) is a versatile and personalized local immunotherapeutic strategy. However, the compromised viability and function of dendritic cells (DCs) in a tumor microenvironment (TME) largely limit the therapeutic efficacy. We designed a hybrid nanoparticle-based ISV, which accomplished superior cancer immunotherapy via simultaneously scavenging reactive oxygen species (ROS) and activating the stimulator of interferon genes (STING) pathway in DCs. This ISV was constructed by encapsulating a chemodrug, SN38, into diselenide bond-bridged organosilica nanoparticles, followed by coating with a Mn2+-based metal phenolic network. We show that this ISV can activate the STING pathway through Mn2+ and SN38 comediated signaling and simultaneously scavenge preexisting H2O2 in the TME and Mn2+-catalyzed •OH by leveraging the antioxidant property of diselenide and polyphenol. This ISV effectively activated DCs and protected them from oxidative damage, leading to remarkable downstream T cell activation and systemic antitumor immunity. This work highlights a nanoparticle design that manipulates DCs in the TME for improving the ISV.

YTHDF2 in peritumoral hepatocytes mediates chemotherapy-induced antitumor immune responses through CX3CL1-mediated CD8+ T cell recruitment

Peritumoral hepatocytes are critical components of the liver cancer microenvironment, However, the role of peritumoral hepatocytes in the local tumor immune interface and the underlying molecular mechanisms have not been elucidated. YTHDF2, an RNA N6-methyladenosine (m6A) reader, is critical for liver tumor progression. The function and regulatory roles of YTHDF2 in peritumoral hepatocytes are unknown. This study demonstrated that oxaliplatin (OXA) upregulated m6A modification and YTHDF2 expression in hepatocytes. Studies using tumor-bearing liver-specific Ythdf2 knockout mice revealed that hepatocyte YTHDF2 suppresses liver tumor growth through CD8+ T cell recruitment and activation. Additionally, YTHDF2 mediated the response to immunotherapy. Mechanistically, OXA upregulated YTHDF2 expression by activating the cGAS-STING signaling pathway and consequently enhanced the therapeutic outcomes of immunotherapeutic interventions. Ythdf2 stabilized Cx3cl1 transcripts in an m6A-dependent manner, regulating the interplay between CD8+ T cells and the progression of liver malignancies. Thus, this study elucidated the novel role of hepatocyte YTHDF2, which promotes therapy-induced antitumor immune responses in the liver. The findings of this study provide valuable insights into the mechanism underlying the therapeutic benefits of targeting YTHDF2.

Cobalt(III) prodrug-based nanomedicine for inducing immunogenic cell death and enhancing chemo-immunotherapy

Despite impressive advances in immune checkpoint blockade therapy, its efficacy as a standalone treatment remains limited. The influence of chemotherapeutic agents on tumor immunotherapy has progressively come to light in recent years, positioning them as promising contenders in the realm of combination therapy options for tumor immunotherapy. Herein, we present the rational design, synthesis, and biological evaluation of the first example of a Co(III) prodrug (Co2) capable of eliciting a localized cytotoxic effect while simultaneously inducing a systemic immune response via type II immunogenic cell death (ICD). To enhance its pharmacological properties, a glutathione-sensitive polymer was synthesized, and Co2 was encapsulated into polymeric nanoparticles (NP-Co2) to improve efficacy. Furthermore, NP-Co2 activates the GRP78/p-PERK/p-eIF2α/CHOP pathway, thereby inducing ICD in cancer cells. This facilitates the transformation of "cold tumors" into "hot tumors" and augments the effectiveness of the PD-1 monoclonal antibody (αPD-1). In essence, this nanomedicine, utilizing Co(III) prodrugs to induce ICD, provides a promising strategy to enhance chemotherapy and αPD-1 antibody-mediated cancer immunotherapy.

Encapsulation of Cu(II) Terpyridine Complexes into Polymeric Nanoparticles for Enhanced Anticancer Therapy

Cancer is one of the deadliest diseases worldwide. One of the most commonly applied therapeutic techniques to combat this disease is chemotherapy. Despite its success, the majority of clinically applied chemotherapeutic agents are associated with strong side effects and drug resistance. To overcome this limitation, much research efforts are devoted toward the development of new anticancer agents. Among the most promising class of compounds, Cu(II) complexes have emerged. Despite their strong cytotoxic effect, these agents are typically associated with low water solubility, low stability, and poor tumor selectivity. To overcome these limitations, herein, we report on the encapsulation of a promising Cu(II) terpyridine complex with the Pluronic F-127/Poloxamer-407 polymeric carrier into nanoparticles. Besides overcoming the pharmacological drawbacks, the nanoparticles were able to eradicate human breast adenocarcinoma monolayer cells as well as challenging multicellular tumor spheroids at nanomolar concentrations.

Platinum-based chemotherapy: trends in organic nanodelivery systems

Despite the investment in platinum drugs research, cisplatin, carboplatin and oxaliplatin are still the only Pt-based compounds used as first line treatments for several cancers, with a few other compounds being approved for administration in some Asian countries. However, due to the severe and worldwide impact of oncological diseases, there is an urge for improved chemotherapeutic approaches. Furthermore, the pharmaceutical application of platinum complexes is hindered by their inherent toxicity and acquired resistance. Nanodelivery systems rose as a key strategy to overcome these challenges, with recognized versatility and ability towards improving the safety, bioavailability and efficacy of the available drugs. Among the known nanocarriers, organic systems have been widely applied, taking advantage of their potential as drug vehicles. Researchers have mainly focused on the development of lipidic and polymeric carriers, including supramolecular structures, with an overall improvement of encapsulated platinum complexes. Herein, an overview of recent trends and strategies is presented, with the main focus on the encapsulation of platinum compounds into organic nanocarriers, showcasing the evolution in the design and development of these promising systems. This comprehensive review highlights formulation methods as well as characterization procedures, providing insights that may be helpful for the development of novel platinum nanocarriers aiming at future pharmaceutical applications.

Engineered nanoparticles for precise targeted drug delivery and enhanced therapeutic efficacy in cancer immunotherapy

The advent of cancer immunotherapy has imparted a transformative impact on cancer treatment paradigms by harnessing the power of the immune system. However, the challenge of practical and precise targeting of malignant cells persists. To address this, engineered nanoparticles (NPs) have emerged as a promising solution for enhancing targeted drug delivery in immunotherapeutic interventions, owing to their small size, low immunogenicity, and ease of surface modification. This comprehensive review delves into contemporary research at the nexus of NP engineering and immunotherapy, encompassing an extensive spectrum of NP morphologies and strategies tailored toward optimizing tumor targeting and augmenting therapeutic effectiveness. Moreover, it underscores the mechanisms that NPs leverage to bypass the numerous obstacles encountered in immunotherapeutic regimens and probes into the combined potential of NPs when co-administered with both established and novel immunotherapeutic modalities. Finally, the review evaluates the existing limitations of NPs as drug delivery platforms in immunotherapy, which could shape the path for future advancements in this promising field.

Elucidation of Spatial Cooperativity in Chemo-Immunotherapy by a Sequential Dual-pH-Responsive Drug Delivery System

Combining immune checkpoint blockade with chemotherapy through nanotechnology is promising in terms of safety and efficacy. However, the distinct subcellular distribution of each ingredient's action site makes it challenging to acquire an optimal synergism. Herein, a dual-pH responsive hybrid polymeric micelle system, HNP(αPDL16.9, Dox5.3), is constructed as a proof-of-concept for the spatial cooperativity in chemo-immunotherapy. HNP retains the inherent pH-transition of each polymer, with stepwise disassembly under discrete pH thresholds. Within weakly acidic extracellular tumor environment, αPDL1 is first released to block the checkpoint on cell membranes. The remaining intact Doxorubicin-loaded micelle NP(Dox)5.3 displays significant tropism toward tumor cells and releases Dox upon lysosomal pH for efficient tumor immunogenic cell death without immune toxicity. This sequential-released pattern boosts DC activation and primes CD8+ T cells, leading to enhanced therapeutic performance than single agent or an inverse-ordered combination in multiple murine tumor models. Using HNP, the indispensable role of conventional type 1 DC (cDC1) is identified in chemo-immunotherapy. A co-signature of cDC1 and CD8 correlates with cancer patient survival after neoadjuvant Pembrolizumab plus chemotherapy in clinic. This study highlights spatial cooperativity of chemo- and immuno-agents in immunoregulation and provides insights into the rational design of drug combination for future nanotherapeutics development.

Highly cytotoxic Cu(II) terpyridine complexes as chemotherapeutic agents

Cancer is considered as the biggest medicinal challenge worldwide. During a typical treatment, the tumorous tissue is removed in a surgical procedure and the patient further treated by chemotherapy. One of the most frequently applied drugs are platinum complexes. Despite their clinical success, these compounds are associated with severe side effects and low therapeutic efficiency. To overcome these limitations, herein, the synthesis and biological evaluation of Cu(II) terpyridine complexes as chemotherapeutic drug candidates is suggested. The compounds were found to be highly cytotoxic in the nanomolar range against various cancer cell lines. Mechanistic insights revealed that the compounds primarily accumulated in the cytoplasm and generated reactive oxygen species in this organelle, triggering cell death by apoptosis. Based on their high therapeutic effect, these metal complexes could serve as a starting point for further drug development.

Activating CD8+ T Cells by Pt(IV) Prodrug-Based Nanomedicine and aPD-L1 Antibody for Enhanced Cancer Immunotherapy

Recent years have witnessed substantial progress in cancer immunotherapy, specifically T cell-based therapies. However, the application of T cell therapies has been primarily limited to hematologic malignancies, with limited success in the treatment of solid tumors. The main challenge in treating solid tumor is immune escape, which is characterized by reduced antigenicity, diminished immunogenicity, and the development of suppressive tumor immune microenvironments. To address these obstacles and restore T cell-mediated anti-tumor responses, a novel nanoparticle formulation known as PRA@Oxa-c16 is developed. This innovative approach combines retinoic acid and Pt(IV) to specifically target and overcome immune escape. Notably, the therapeutic efficacy of PRA@Oxa-c16 primarily relies on its ability to induce anti-tumor T cell responses, in contrast to the cytotoxicity associated with conventional chemotherapeutic agents. When combined with an immune checkpoint blockade, anti-programmed death-ligand 1 antibody, PRA@Oxa-c16 effectively eliminates solid tumors and induces immune memory responses, which prevent tumor metastasis and recurrence. This promising approach holds great potential for enhancing the treatment of solid tumors with T cell-based immunotherapy.

Dinuclear Rhenium(I) Tricarbonyl Complexes as Anticancer Drug Candidates

Cancer is one of the deadliest diseases worldwide. Chemotherapy remains one of the most dominant forms for anticancer treatment. Despite their clinical success, the used chemotherapeutic agents are associated with severe side effect and pharmacological limitations. To overcome these drawbacks there is a need for the development of new types of chemotherapeutic agents. Herein, the chemical synthesis and biological evaluation of dinuclear rhenium(I) complexes as potential chemotherapeutic drug candidates are proposed. The metal complexes were found to be internalized by an energy dependent endocytosis pathway, primary accumulating in the mitochondria. The rhenium(I) complexes demonstrated to induce cell death against a variety of cancer cells in the micromolar range through apoptosis. The lead compound showed to eradicate a pancreatic carcinoma multicellular tumor spheroid at micromolar concentrations.

Novel Pt(IV) complex OAP2 induces STING activation and pyroptosis via mitochondrial membrane remodeling for synergistic chemo-immunotherapy

Mitochondrial membrane remodeling can trigger the release of mitochondrial DNA (mtDNA), leading to the activation of cellular oxidative stress and immune responses. While the role of mitochondrial membrane remodeling in promoting inflammation in hepatocytes is well-established, its effects on tumors have remained unclear. In this study, we designed a novel Pt(IV) complex, OAP2, which is composed of oxaliplatin (Oxa) and acetaminophen (APAP), to enhance its anti-tumor effects and amplify the immune response. Our findings demonstrate that OAP2 induces nuclear DNA damage, resulting in the production of nuclear DNA. Additionally, OAP2 downregulates the expression of mitochondrial Sam50, to promote mitochondrial membrane remodeling and trigger mtDNA secretion, leading to double-stranded DNA accumulation and ultimately synergistically activating the intracellular cGAS-STING pathway. The mitochondrial membrane remodeling induced by OAP2 overcomes the limitations of Oxa in activating the STING pathway and simultaneously promotes gasdermin-D-mediated cell pyroptosis. OAP2 also promotes dendritic cell maturation and enhances the quantity and efficacy of cytotoxic T cells, thereby inhibiting cancer cell proliferation and metastasis. Briefly, our study introduces the first novel small-molecule inhibitor that regulates mitochondrial membrane remodeling for active immunotherapy in anti-tumor research, which may provide a creative idea for targeting organelle in anti-tumor therapy.

Tissue biomarkers of immune checkpoint inhibitor therapy

Cancer immunotherapy has been rejuvenated by the growing understanding of the immune system's role in tumor activity over the past two decades. During cancer initiation and progression, tumor cells employ various mechanisms that resemble peripheral immune tolerance to evade the antitumor responses of the immune system. Immune checkpoint molecules are the major mechanism of immune resistance that are exploited by tumor cells to inhibit T-cell activation and suppress immune responses. The targeting of immune checkpoint pathways has led to substantial improvements in survival rates in a number of solid cancers. However, a lack of understanding of the heterogeneity of the tumor microenvironment (TME) has resulted in inefficient therapy responses. A greater understanding of the TME is needed to identify patients likely to respond, and those that will have resistance to immune checkpoint inhibitors (ICIs). Advancement in spatial single-cell technologies has allowed deeper insight into the phenotypic and functional diversities of cells in the TME. In this review, we provide an overview of ICI biomarkers and highlight how high-dimensional spatially resolved, single-cell approaches provide deep molecular insights into the TME and allow for the discovery of biomarkers of clinical benefit.

Simultaneous Activation of Pyroptosis and cGAS-STING Pathway with Epigenetic/ Photodynamic Nanotheranostic for Enhanced Tumor Photoimmunotherapy

Promoting innate immunity through pyroptosis induction or the cyclic GMP-AMP synthase-stimulator of interferon gene (cGAS-STING) pathway activation has emerged as a potent approach to counteract the immunosuppressive tumor microenvironment and elicit systemic antitumor immunity. However, current pyroptosis inducers and STING agonists often suffer from limitations including instability, unpredictable side effects, or inadequate intracellular expression of gasdermin and STING. Here, a tumor-specific nanotheranostic platform that combines photodynamic therapy (PDT) with epigenetic therapy to simultaneously activate pyroptosis and the cGAS-STING pathway in a light-controlled manner is constructed. This approach involves the development of oxidation-sensitive nanoparticles (NP1) loaded with the photosensitizer TBE, along with decitabine nanomicelles (NP2). NP2 enables the restoration of STING and gasdermin E (GSDME) expression, while NP1-mediated PDT facilitates the release of DNA fragments from damaged mitochondria to potentiate the cGAS-STING pathway, and promotes the activation of caspase-3 to cleave the upregulated GSDME into pore-forming GSDME-N terminal. Subsequently, the released inflammatory cytokines facilitate the maturation of antigen-presentation cells, triggering T cell-mediated antitumor immunity. Overall, this study presents an elaborate strategy for simultaneous photoactivation of pyroptosis and the cGAS-STING pathway, enabling targeted photoimmunotherapy in immunotolerant tumors. This innovative approach holds significant promise in overcoming the limitations associated with existing therapeutic modalities and represents a valuable avenue for future clinical applications.

Self-Assembly of Erlotinib-Platinum(II) Complexes for Epidermal Growth Factor Receptor-Targeted Photodynamic Therapy

Due to cell mutation and self-adaptation, the application of clinical drugs with early epidermal growth factor receptor (EGFR)-targeted inhibitors is severely limited. To overcome this limitation, herein, the synthesis and in-depth biological evaluation of an erlotinib-platinum(II) complex as an EGFR-targeted anticancer agent is reported. The metal complex is able to self-assemble inside an aqueous solution and readily form nanostructures with strong photophysical properties. While being poorly toxic toward healthy cells and upon treatment in the dark, the compound was able to induce a cytotoxic effect in the very low micromolar range upon irradiation against EGFR overexpressing (drug resistant) human lung cancer cells as well as multicellular tumor spheroids. Mechanistic insights revealed that the compound was able to selectively degrade the EGFR using the lysosomal degradation pathway upon generation of singlet oxygen at the EGFR. We are confident that this work will open new avenues for the treatment of EGFR-overexpressing tumors.

Disruption of Iron Homeostasis to Induce Ferroptosis with Albumin-Encapsulated Pt(IV) Nanodrug for the Treatment of Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common pathological type of lung cancer , accounting for approximately 85% of lung cancers. For more than 40 years, platinum (Pt)-based drugs are still one of the most widely used anticancer drugs even in the era of precision medicine and immunotherapy. However, the clinical limitations of Pt-based drugs, such as serious side effects and drug resistance, have not been well solved. This study constructs a new albumin-encapsulated Pt(IV) nanodrug (HSA@Pt(IV)) based on the Pt(IV) drug and nanodelivery system. The characterization of nanodrug and biological experiments demonstrate its excellent drug delivery and antitumor effects. The multi-omics analysis of the transcriptome and the ionome reveals that nanodrug can activate ferroptosis by affecting intracellular iron homeostasis in NSCLC. This study provides experimental evidence to suggest the potential of HSA@Pt(IV) as a nanodrug with clinical application.

cGAS-STING Pathway Activation and Systemic Anti-Tumor Immunity Induction via Photodynamic Nanoparticles with Potent Toxic Platinum DNA Intercalator Against Uveal Melanoma

The cGAS-STING pathway, as a vital innate immune signaling pathway, has attracted considerable attention in tumor immunotherapy research. However, STING agonists are generally incapable of targeting tumors, thus limiting their clinical applications. Here, a photodynamic polymer (P1) is designed to electrostatically couple with 56MESS-a cationic platinum (II) agent-to form NPPDT -56MESS. The accumulation of NPPDT -56MESS in the tumors increases the efficacy and decreases the systemic toxicity of the drugs. Moreover, NPPDT -56MESS generates reactive oxygen species (ROS) under the excitation with an 808 nm laser, which then results in the disintegration of NPPDT -56MESS. Indeed, the ROS and 56MESS act synergistically to damage DNA and mitochondria, leading to a surge of cytoplasmic double-stranded DNA (dsDNA). This way, the cGAS-STING pathway is activated to induce anti-tumor immune responses and ultimately enhance anti-cancer activity. Additionally, the administration of NPPDT -56MESS to mice induces an immune memory effect, thus improving the survival rate of mice. Collectively, these findings indicate that NPPDT -56MESS functions as a chemotherapeutic agent and cGAS-STING pathway agonist, representing a combination chemotherapy and immunotherapy strategy that provides novel modalities for the treatment of uveal melanoma.

Developing a Ruthenium(III) Complex to Trigger Gasdermin E-Mediated Pyroptosis and an Immune Response Based on Decitabine and Liposomes: Targeting Inhibition of Gastric Tumor Growth and Metastasis

To develop next-generation metal drugs with high efficiency and low toxicity for targeting inhibition of gastric tumor growth and metastasis, we not only optimized a series of ruthenium (Ru, III) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes to obtain a Ru(III) complex (4b) with remarkable cytotoxicity in vitro but also constructed a 4b-decitabine (DCT)/liposome (Lip) delivery system (4b-DCT-Lip). The in vivo results showed that 4b-DCT-Lip not only had a stronger capacity to inhibit gastric tumor growth and metastasis than 4b-DCT but also addressed the co-delivery problems of 4b-DCT and improved their targeting ability. Furthermore, we confirmed the mechanism of 4b-DCT/4b-DCT-Lip inhibiting the growth and metastasis of a gastric tumor. DCT-upregulated gasdermin E (GSDME) was cleaved by 4b-activated caspase-3 to afford GSDME-N terminal and then was aggregated to form nonselective pores on the cell membrane of a gastric tumor, thereby inducing pyroptosis and a pyroptosis-induced immune response.

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.

NIR-II fluorescence and PA imaging guided activation of STING pathway in photothermal therapy for boosting cancer immunotherapy by theranostic thermosensitive liposomes

Photothermal immunotherapy has shown great potential for efficient cancer treatment. However, the immunosuppressive tumor microenvironment forms a heavy barrier for photothermal-induced anti-tumor immunity by inhibiting dendritic cell (DC) maturation and cytotoxic T cell response. Moreover, the lack of reliable spatiotemporal imaging modalities makes photothermal immunotherapy difficult to guide tumor ablation and monitor therapeutic outcomes in real time. Herein, we designed a theranostic thermosensitive liposome (PLDD) as a versatile nanoplatform to boost the adaptive anti-tumor immunity of photothermal immunotherapy and to achieve multiple bioimaging modalities in a real-time manner. PLDD contains two major functional components: a multifunctional photothermal agent (DTTB) and an immune potentiator STING pathway agonist (DMXAA). Upon irradiation, the heat generated by DTTB induced the immunogenic cell death (ICD) of the tumor and dissociated the structure of thermosensitive liposome to release DMXAA, which ultimately activated the STING pathway and promoted the ICD-induced immune response by increasing DC cell maturation and T cell recruitment. Moreover, the DTTB in PLDD displayed excellent second near-infrared (NIR-II) fluorescence and photoacoustic (PA) dual-modal imaging, which provided omnibearing information on the tumor and guided the subsequent therapeutic operation. Therefore, this versatile PLDD with light-triggered promotion of anti-tumor immunity and multiple spatiotemporal imaging profiles holds great potential for the future development of cancer immunotherapy.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Encapsulation of Ru(II) Polypyridine Complexes for Tumor-Targeted Anticancer Therapy

Ru(II) polypyridine complexes have attracted much attention as anticancer agents because of their unique photophysical, photochemical, and biological properties. Despite their promising therapeutic profile, the vast majority of compounds are associated with poor water solubility and poor cancer selectivity. Among the different strategies employed to overcome these pharmacological limitations, many research efforts have been devoted to the physical or covalent encapsulation of the Ru(II) polypyridine complexes into nanoparticles. This article highlights recent developments in the design, preparation, and physicochemical properties of Ru(II) polypyridine complex-loaded nanoparticles for their potential application in anticancer therapy.

Delivery of Immunostimulatory Cargos in Nanocarriers Enhances Anti-Tumoral Nanovaccine Efficacy

Finding a long-term cure for tumor patients still represents a major challenge. Immunotherapies offer promising therapy options, since they are designed to specifically prime the immune system against the tumor and modulate the immunosuppressive tumor microenvironment. Using nucleic-acid-based vaccines or cellular vaccines often does not achieve sufficient activation of the immune system in clinical trials. Additionally, the rapid degradation of drugs and their non-specific uptake into tissues and cells as well as their severe side effects pose a challenge. The encapsulation of immunomodulatory molecules into nanocarriers provides the opportunity of protected cargo transport and targeted uptake by antigen-presenting cells. In addition, different immunomodulatory cargos can be co-delivered, which enables versatile stimulation of the immune system, enhances anti-tumor immune responses and improves the toxicity profile of conventional chemotherapeutic agents.

Advances in HPV-associated tumor management: Therapeutic strategies and emerging insights

With the rapid increase in the incidence of cervical cancer, anal cancer and other cancers, human papillomavirus (HPV) infection has become a growing concern. Persistent infection with high-risk HPV is a major cause of malignant tumors. In addition, microbiota and viruses such as human immunodeficiency virus, herpes simplex virus, and Epstein-Barr virus are closely associated with HPV infection. The limited effectiveness of existing treatments for HPV-associated tumors and the high rates of recurrence and metastasis in patients create an urgent need for novel and effective approaches. In recent years, HPV vaccine coverage has increased and can reduce the incidence of serious adverse events. Overall, this article provides a comprehensive overview of HPV biology, microbiome, and other viral interactions in cancer development, highlighting the need for a more comprehensive approach to cancer prevention and treatment. Current and emerging HPV-related cancer control and treatment strategies are also further explored.

Immunogenic Cell Death Inducing Metal Complexes for Cancer Therapy

Cancer is one of the deadliest diseases worldwide. Recent statistics have shown that metastases and tumor relapse are the leading causes of cancer-associated deaths. While traditional treatments are able to efficiently remove the primary tumor, secondary tumors remain poorly accessible. Capitalizing on this there is an urgent need for novel treatment modalities. Among the most promising approaches, increasing research interest has been devoted to immunogenic cell death inducing agents that are able to trigger localized cell death of the cancer cells as well as induce an immune response inside the whole organism. Preliminary studies have shown that immunogenic cell death inducing compounds could be able to overcome metastatic and relapsing tumors. Herein, the application of metal complexes as immunogenic cell death inducing compounds is systematically reviewed.