Polysaccharide-Based Stimulus-Responsive Nanomedicines for Combination Cancer Immunotherapy

Cancer immunotherapy is a promising antitumor approach, whereas nontherapeutic side effects, tumor microenvironment (TME) intricacy, and low tumor immunogenicity limit its therapeutic efficacy. In recent years, combination immunotherapy with other therapies has been proven to considerably increase antitumor efficacy. However, achieving codelivery of the drugs to the tumor site remains a major challenge. Stimulus-responsive nanodelivery systems show controlled drug delivery and precise drug release. Polysaccharides, a family of potential biomaterials, are widely used in the development of stimulus-responsive nanomedicines due to their unique physicochemical properties, biocompatibility, and modifiability. Here, the antitumor activity of polysaccharides and several combined immunotherapy strategies (e.g., immunotherapy combined with chemotherapy, photodynamic therapy, or photothermal therapy) are summarized. More importantly, the recent progress of polysaccharide-based stimulus-responsive nanomedicines for combination cancer immunotherapy is discussed, with the focus on construction of nanomedicine, targeted delivery, drug release, and enhanced antitumor effects. Finally, the limitations and application prospects of this new field are discussed.     

Leveraging β-Adrenergic Receptor Signaling Blockade for Improved Cancer Immunotherapy Through Biomimetic Nanovaccine

The establishment of effective antitumor immune responses of vaccines is mainly limited by insufficient priming tumor infiltration of T cells and immunosuppressive tumor microenvironment (TME). Targeting β-adrenergic receptor (β-AR) signaling exerts promising benefits on reversing the suppressive effects directly on T cells, but it appears to have considerably limited antitumor performance when combined with vaccine-based immunotherapies. Herein, a tumor membrane-coated nanoplatform for codelivery of adjuvant CpG and propranolol (Pro), a β-AR inhibitor is designed. The biomimetic nanovaccine displayed an improved accumulation in lymph nodes and sufficient drug release, thereby inducing dendritic cell maturation and antigen presentation. Meanwhile, the integration of vaccination and blockade of β-AR signaling not only promoted the priming of the naive CD8+ T cells and effector T cell egress from lymph nodes, but also alleviated the immunosuppressive TME by decreasing the frequency of immunosuppressive cells and increasing the tumor infiltration of B cells and NK cells. Consequently, the biomimetic nanovaccines outperformed greater prophylactic and therapeutic efficacy than nanovaccines without Pro encapsulation in B16-F10 melanoma mice. Taken together, the work explored a biomimetic nanovaccine for priming tumor infiltration of T cells and immunosuppressive TME regulation, offering tremendous potential for a combined β-AR signaling-targeting strategy in cancer immunotherapy.     

Biomineralized Bacterial Outer Membrane Vesicles Potentiate Safe and Efficient Tumor Microenvironment Reprogramming for Anticancer Therapy

The highly immunosuppressive tumor microenvironment (TME) in solid tumors often dampens the efficacy of immunotherapy. In this study, bacterial outer membrane vesicles (OMVs) are demonstrated as powerful immunostimulants for TME reprogramming. To overcome the obstacles of antibody-dependent clearance and high toxicity induced by OMVs upon intravenous injection (a classic clinically relevant delivery mode), calcium phosphate (CaP) shells are employed to cover the surface of OMVs, which enables potent OMV-based TME reprograming without side effects. Meanwhile, the pH-sensitive CaP shells facilitate the neutralization of acidic TME, leading to highly beneficial M2-to-M1 polarization of macrophages for improved antitumor effect. Moreover, the outer shells can be integrated with functional components like folic acid or photosensitizer agents, which facilitates the use of the OMV-based platform in combination therapies for a synergic therapeutic effect.     

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H₂O₂, GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.     

M2 Macrophage Membrane-Mediated Biomimetic-Nanoparticle Carrying COX-siRNA Targeted Delivery for Prevention of Tendon Adhesions by Inhibiting Inflammation

Tendon adhesion is the most common outcome of tendon or tendon-to-bone healing after injury. Our group developed a hydrogel-nanoparticle sustained-release system previously to inhibit cyclooxygenases (COXs) expression and consequently prevent tendon adhesion and achieved satisfactory results. However, effective treatment of multiple tendon adhesions is always a challenge in research on the prevention of tendon adhesion. In the present study, an M2M@PLGA/COX-siRNA delivery system is successfully constructed using the cell membranes of M2 macrophages and poly (lactic-co-glycolic acid) (PLGA) nanoparticles. Targeting properties and therapeutic effects are observed in mice or rat models of flexor digitorum longus (FDL) tendon injury combined with rotator cuff injury. The results showed that the M2M@PLGA/COX-siRNA delivery system has low toxicity and remarkable targeting properties to the injured areas. Treatment with the M2M@PLGA/COX-siRNA delivery system reduced the inflammatory reaction and significantly improved tendon adhesion in both the FDL tendon and rotator cuff tissues. These findings indicate that the M2M@PLGA delivery system can provide an effective biological strategy for preventing multiple tendon adhesions.     

A ceramic-based anticancer drug delivery system to treat breast cancer

Drug delivery systems offer the advantage of sustained targeted release with minimal side effect. In the present study, the therapeutic efficacy of a porous silica–calcium phosphate nanocomposite (SCPC) as a new delivery system for 5-Fluorouracil (5-FU) was evaluated in vitro and in vivo. In vitro studies showed that two formulations; SCPC50/5-FU and SCPC75/5-FU hybrids were very cytotoxic for 4T1 mammary tumor cells. In contrast, control SCPCs without drug did not show any measurable toxic effect. Release kinetics studies showed that SCPC75/5-FU hybrid provided a burst release of 5-FU in the first 24 h followed by a sustained release of a therapeutic dose (30.7 μg/day) of the drug for up to 32 days. Moreover, subcutaneous implantation of SCPC75/5-FU hybrid disk in an immunocompetent murine model of breast cancer stopped 4T1 tumor growth. Blood analyses showed comparable concentrations of Ca, P and Si in animals implanted with or without SCPC75 disks. These results strongly suggest that SCPC/5-FU hybrids can provide an effective treatment for solid tumors with minimal side effects.     

Nanodrug Inducing Autophagy Inhibition and Mitochondria Dysfunction for Potentiating Tumor Photo-Immunotherapy

Anticancer immunotherapy is hampered by the poor tumor immunogenicity and immunosuppressive tumor microenvironment (TME). Herein, a liposome nanodrug co-encapsulating doxycycline hydrochloride (Doxy) and chlorin e6 (Ce6) to simultaneously induce autophagy inhibition and mitochondria dysfunction for potentiating tumor photo-immunotherapy is developed. Under near infrared laser irradiation, Ce6 generates cytotoxic reactive oxygen species (ROS) and elicits robust photodynamic therapy (PDT)-induced immunogenic cell death (ICD) for immunosuppressive TME remodeling. In addition, Doxy induced mitochondria dysfunction, which increases ROS generation and enhances PDT to exert more potent killing effect and more powerful ICD. Meanwhile, Doxy increases MHC-I expression on tumor cells surface by efficient autophagy inhibition, leading to more efficient antigen presentation and CTLs recognition to increase tumor immunogenicity. The nanodrugs elicit remarkable antitumor therapy by combining Ce6-mediated PDT and Doxy-induced autophagy inhibition and mitochondria dysfunction. The developed nanodrugs represent a highly efficient strategy for improving cancer immunotherapy.     

pH-responsive dual-functional hydrogel integrating localized delivery and anti-cancer activities for highly effective therapy in PDX of OSCC

As one of the most promising localized drug delivery systems for enhancing therapeutic efficacy and reducing systemic toxicity, supramolecular hydrogels self-assembled from natural products have recently attracted tremendous attention. However, the intricate drug loading process, limited drug entrapment efficacy, and lack of stimulus responsiveness considerably impede their potential for biological applications and raise the need for advanced hydrogel-based delivery systems. Therefore, the development of updated materials that integrate localized delivery and drug activity into a single system is extremely desired and has great potential to overcome the aforementioned shortcomings. In this study, a pH-responsive dual-functional isoG-based supramolecular hydrogel with both localized delivery and anti-cancer activity in one molecule is successfully developed in one pot by following a simple and green procedure. The isoguanosine-phenylboronic-guanosine (isoGPBG) hydrogel exhibits exceptional stability (more than one year), outstanding pH-responsiveness and excellent sustained release capability. Both in vitro and in vivo experiments demonstrate that the isoGPBG hydrogel not only shows acceptable biocompatibility and biodegradability but also significantly inhibit tumor growth (approximately 60% inhibition of tumor growth) and improve overall survival, especially in preclinical patient-derived xenograft (PDX) model of oral squamous cell carcinoma (OSCC). Therefore, the isoGPBG hydrogel, to the best of our knowledge, is the first example of pH-responsive dual-functional isoG-based supramolecular hydrogel integrating localized delivery and anti-cancer activity in one molecule. It is implied that the isoGPBG hydrogel could act as a smart dual-functional localized delivery system in the future for clinical cancer therapy.     

Cancer Modeling‐on‐a‐Chip with Future Artificial Intelligence Integration

Cancer is one of the leading causes of death worldwide, despite the large efforts to improve the understanding of cancer biology and development of treatments. The attempts to improve cancer treatment are limited by the complexity of the local milieu in which cancer cells exist. The tumor microenvironment (TME) consists of a diverse population of tumor cells and stromal cells with immune constituents, microvasculature, extracellular matrix components, and gradients of oxygen, nutrients, and growth factors. The TME is not recapitulated in traditional models used in cancer investigation, limiting the translation of preliminary findings to clinical practice. Advances in 3D cell culture, tissue engineering, and microfluidics have led to the development of “cancer‐on‐a‐chip” platforms that expand the ability to model the TME in vitro and allow for high‐throughput analysis. The advances in the development of cancer‐on‐a‐chip platforms, implications for drug development, challenges to leveraging this technology for improved cancer treatment, and future integration with artificial intelligence for improved predictive drug screening models are discussed.     

Simultaneous Quantification of Tumor Uptake for Targeted and Nontargeted Liposomes and Their Encapsulated Contents by ICPMS

Liposomes are intensively being developed for biomedical applications including drug and gene delivery. However, targeted liposomal delivery in cancer treatment is a very complicated multistep process. Unfavorable liposome biodistribution upon intravenous administration and membrane destabilization in blood circulation could result in only a very small fraction of cargo reaching the tumors. It would therefore be desirable to develop new quantitative strategies to track liposomal delivery systems to improve the therapeutic index and decrease systemic toxicity. Here, we developed a simple and nonradiative method to quantify the tumor uptake of targeted and nontargeted control liposomes as well as their encapsulated contents simultaneously. Specifically, four different chelated lanthanide metals were encapsulated or surface-conjugated onto tumor-targeted and nontargeted liposomes, respectively. The two liposome formulations were then injected into tumor-bearing mice simultaneously, and their tumor delivery was determined quantitatively via inductively coupled plasma mass spectroscopy (ICPMS), allowing for direct comparisons. Tumor uptake of the liposomes themselves and their encapsulated contents was consistent with targeted and nontargeted liposome formulations that were injected individually.     

Functionalized DNA Enables Programming Exosomes/Vesicles for Tumor Imaging and Therapy

Exosomes serve as significant information carriers that regulate important physiological and pathological processes. Herein, functionalized DNA is engineered to be a hinge that anchors quantum dots (QDs) onto the surface of exosomes, realizing a moderate and biocompatible labeling strategy. The QDs‐labeled exosomes (exosome–DNA–QDs complex) can be swiftly engulfed by tumor cells, indicating that exosome–DNA–QDs can be applied as a specific agent for tumor labeling. Furthermore, the engineered artificial vesicles of M1 macrophages (M1mv) are constructed via a pneumatic liposome extruder. The results reveal that the individual M1mv can kill tumor cells and realize desirable biological treatment. To reinforce the antitumor efficacy of M1mv and the specificity of drug release, a target‐triggered drug delivery system is constructed to realize a specific microRNA‐responded delivery system for visual therapy of tumors. These strategies facilitate moderate labeling and functionalization of exosomes/vesicles and construct artificial drug‐delivery vesicles that simultaneously possess biological treatment and chemotherapy functions, and thus have the potential to serve as a new paradigm for tumor labeling and therapy.     

Dendron-polymer hybrid mediated anticancer drug delivery for suppression of mammary cancer

Dendron-polymer-based nanoscale and stimuli-responsive drug delivery systems have shown great promise in tumor-targeting accumulation without significant toxicity.Here we report a dendronized polymer-doxorubicin(DOX)hybrid(DPDH)with an improved in vivo drug delivery efficiency for cancer therapy compared with a linear polymer-DOX conjugate(LPDC).The in vitro drug release profile of DOX indicates that DPDH displays pH-responsive drug release due to cleavage of hydrazone bonds since a greater amount of DOX is released at pH 5.2 at a faster rate than at pH 7.4.DPDH efficiently enters 4 T1 cells and releases DOX to induce cytotoxicity and apoptosis.Owing to the dendronzied structure,DPDH has a significantly longer blood circulation time than LPDC.DPDH substantially enhances the therapeutic efficacy to suppress tumor growth in a 4 T1 mammary cancer model than LPDC as well as free drug,evidenced from tumor growth inhibition,TUNEL assessment and histological analysis.Biosafety of DPDH is also confirmed from hemolysis,body weight shifts during treatment and pathological analysis.This study demonstrates the use of dendronized polymer-DOX hybrids for specific drug molecules is a promising approach for drug delivery.     

Novel PdPtCu Nanozymes for Reprogramming Tumor Microenvironment to Boost Immunotherapy Through Endoplasmic Reticulum Stress and Blocking IDO-Mediated Immune Escape

Breaking immunosuppressive tumor microenvironment (TME) has unique effects on inhibiting tumor growth and recurrence. Here, an endoplasmic reticulum (ER) targeted PdPtCu nanozyme (PNBCT^ER) is prepared to boost immunotherapy. First, PNBCT^ER has three kinds of enzyme activities, including catalase (CAT), glutathione oxidase (GSHOx), and peroxidase (POD)-like activities, which can reshape the TME. Second, PNBCT^ER kills tumor cells by photodynamic therapy (PDT) and photothermal therapy (PTT). Third, guided by T^ER, PNBCT^ER not only realizes the combination therapy of PDT, PTT and chemodynamic therapy (CDT), but also damages the ER of tumor cells and actives antitumor immune response, which breaks through the immune blockade of TME. Finally, the NLG919 blocks the tryptophan/kynurenine immune escape pathway and reverses the immunosuppressive TME. The strategy that reshaping the TME by enzyme catalysis and breaking immunosuppression provides a novel way for the application of combination therapy in tumor.     

A Self-Disguised Nanospy for Improving Drug Delivery Efficiency via Decreasing Drug Protonation

Nanoscale drug carriers play a crucial role in reducing side effects of chemotherapy drugs. However, the mononuclear phagocyte system (MPS) and the drug protonation after nanoparticles (NPs) burst release still limit the drug delivery efficiency. In this work, a self-disguised Nanospy is designed to overcome this problem. The Nanospy is composed of: i) poly (lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) loading doxorubicin is the core structure of the Nanospy. ii) CD47 mimic peptides (CD47p) is linked to NPs which conveyed the “don't eat me” signal. iii) 4-(2-aminoethyl) benzenesulfonamide (AEBS) as the inhibitor of Carbonic anhydrase IX (CAIX) linked to NPs. Briefly, when the Nanospy circulates in the bloodstream, CD47p binds to the regulatory protein α (SIRPα) on the surface of macrophages, which causes the Nanospy escapes from phagocytosis. Subsequently, the Nanospy enriches in tumor and the AEBS reverses the acidic microenvironment of tumor. Due to above characteristics, the Nanospy reduces liver macrophage phagocytosis by 25% and increases tumor in situ DOX concentration by 56% compared to PLGA@DOX treatment. In addition, the Nanospy effectively inhibits tumor growth with a 63% volume reduction. This work presents a unique design to evade the capture of MPS and overcomes the influence of acidic tumor microenvironment (TME) on weakly alkaline drugs.     

Disabling partners in crime: Gold nanoparticles disrupt multicellular communications within the tumor microenvironment to inhibit ovarian tumor aggressiveness

The tumor microenvironment (TME) plays a key role in the poor prognosis of many cancers. However, there is a knowledge gap concerning how multicellular communication among the critical players within the TME contributes to such poor outcomes. Using epithelial ovarian cancer (EOC) as a model, we show how crosstalk among cancer cells (CC), cancer associated fibroblasts (CAF), and endothelial cells (EC) promotes EOC growth. We demonstrate here that co-culturing CC with CAF and EC promotes CC proliferation, migration, and invasion in vitro and that co-implantation of the three cell types facilitates tumor growth in vivo. We further demonstrate that disruption of this multicellular crosstalk using gold nanoparticles (GNP) inhibits these pro-tumorigenic phenotypes in vitro as well as tumor growth in vivo. Mechanistically, GNP treatment reduces expression of several tumor-promoting cytokines and growth factors, resulting in inhibition of MAPK and PI3K-AKT activation and epithelial-mesenchymal transition - three key oncogenic signaling pathways responsible for the aggressiveness of EOC. The current work highlights the importance of multicellular crosstalk within the TME and its role for the aggressive nature of EOC, and demonstrates the disruption of these multicellular communications by self-therapeutic GNP, thus providing new avenues to interrogate the crosstalk and identify key perpetrators responsible for poor prognosis of this intractable malignancy.     

Rosmarinic Acid-Crosslinked Supramolecular Nanoassembly with Self-Regulated Photodynamic and Anti-Metastasis Properties for Synergistic Photoimmunotherapy

A primary concern about photodynamic therapy (PDT) is its inability to regulate the generation levels of reactive oxidative species (ROS) based on the complex microenvironment, resulting in the impairment toward normal tissues and immunosuppression. Besides, tumor metastasis also compromises PDT's efficacy and drives mortality. However, it is very challenging to achieve such two goals within one nanosystem. Here, the nanoassembly (CPR) with self-regulated photodynamic and antimetastasis properties comprises three parts: chlorin e6-conjugated β-cyclodextrin (CD-Ce6) acts as the main PDT agent and ferrocene (Fc)-terminated phenylboronic acid-containing conjugates entering into the cavity of CD-Ce6, as well as rosmarinic acid (RA)–boronic acid crosslinked shell. Compared with non-crosslinked counterpart, CPR displays better stability and enhanced tumor accumulation. Under laser irradiation, CPR generates plenty of ROS to damage tumor cells and induce immunogenic cell death. Mildly acidic TME partly cleaves the crosslinkers to dissociate antioxidant RAs from micelles, which together with Fc in CPR scavenge PDT-induced ROS in the TME. By contrast, under acidic lysosomal conditions, Fc catalyzes abundant H₂O₂ in tumor cells to produce highly cytotoxic •OH, while RA continuously reduces ferroptosis-generated Fc⁺ into Fc, both to augment the PDT efficacy in tumor cells. CPR also remarkably hinders the epithelial-mesenchymal transition to prevent the lung metastasis.     

Tumor associated macrophages reprogrammed by targeted bifunctional bioorthogonal nanozymes for enhanced tumor immunotherapy

Cancer immunotherapy has emerged as a promising cancer treatment. However, its efficacy is often limited by the immunosuppressive tumor microenvironment (TME) in solid tumors. Herein, a new strategy has been presented by using bioorthogonal chemistry to reprogram TME. We designed a bifunctional mannose (Man) vector decorated palladium bioorthogonal nanozyme for in-situ synthesis of histone deacetylase inhibitor (HDACi) vorinostat (FDA approved) with the ability to remodel tumor microenvironment. To the best of our knowledge, this is the first report to use a bioorthogonal nanozyme for cancer immunotherapy. In particular, the nanozyme could preferentially accumulate in M2 macrophages (termed M2Φ) to achieve local M2 re-education, which effectively avoided unnecessary inflammation in normal tissues. Moreover, vorinostat-induced TME reprogramming was synergistic with peroxidase-like activity of the nanozyme, and achieved enhanced tumor synergistic immunotherapy. In colon cancer (CT26)-tumor-bearing BALB/c mice, the nanozyme demonstrated macrophages polarization targeting M2Φ and activation of innate immune system, resulting in significantly enhanced tumor growth inhibition. Our work not only provides a new effective way to reprogram TME in vivo, but also shed light on the design of novel bioorthogonal nanozymes for cancer immunotherapy.     

A Trojan-Horse-Like Biomimetic Nano-NK to Elicit an Immunostimulatory Tumor Microenvironment for Enhanced GBM Chemo-Immunotherapy

Although the chemo- and immuno-therapies have obtained good responses for several solid tumors, including those with brain metastasis, their clinical efficacy in glioblastoma (GBM) is disappointing. The lack of safe and effective delivery systems across the blood-brain barrier (BBB) and the immunosuppressive tumor microenvironment (TME) are two main hurdles for GBM therapy. Herein, a Trojan-horse-like nanoparticle system is designed, which encapsulates biocompatible PLGA-coated temozolomide (TMZ) and IL-15 nanoparticles (NPs) with cRGD-decorated NK cell membrane (R-NKm@NP), to elicit the immunostimulatory TME for GBM chemo-immunotherapy. Taking advantage of the outer NK cell membrane cooperating with cRGD, the R-NKm@NPs effectively traversed across the BBB and targeted GBM. In addition, the R-NKm@NPs exhibited good antitumor ability and prolonged the median survival of GBM-bearing mice. Notably, after R-NKm@NPs treatment, the locally released TMZ and IL-15 synergistically stimulated the proliferation and activation of NK cells, leading to the maturation of dendritic cells and infiltration of CD8⁺ cytotoxic T cells, eliciting an immunostimulatory TME. Lastly, the R-NKm@NPs not only effectively prolonged the metabolic cycling time of the drugs in vivo, but also has no noticeable side effects. This study may offer valuable insights for developing biomimetic nanoparticles to potentiate GBM chemo- and immuno-therapies in the future.     

Self‐Assembly of an Amphiphilic Janus Camptothecin–Floxuridine Conjugate into Liposome‐Like Nanocapsules for More Efficacious Combination Chemotherapy in Cancer

The combination of camptothecin (CPT) and fluoropyrimidine derivatives acts synergistically at a 1:1 molar ratio. Practically, the greatest challenge is the development of a single liposomal formulation that can both encapsulate and maintain this drug combination at an exact 1:1 ratio to achieve coordinated pharmacokinetics. Consequently, a new type of liposome‐like nanocapsule (NC) is developed from a highly symmetric Janus camptothecin–floxuridine conjugate (JCFC) amphiphile, which is synthesized by coupling two hydrophobic CPT molecules and two hydrophilic floxuridine (FUDR) molecules to multivalent pentaerythritol via a hydrolyzable ester linkage. JCFC NCs possess remarkably high drug‐loading contents, and no premature release because of the highly stable co‐delivery of the drug combination without the need for any carrier. It is shown that JCFC NCs consistently provide synergy and avoid antagonism in a broad panel of tumor cell lines. In vivo delivery of JCFC NCs leads to longer blood retention half‐life, higher tumorous accumulation and cellular uptake of drugs, and greatly enhanced efficacy in murine tumor models compared to CPT, FUDR, and CPT + FUDR. This liposomal strategy can be extended to other hydrophilic and hydrophobic anticancer drugs that are coupled to pentaerythritol to self‐assemble into nanocapsules for drug self‐delivery, pointing to potential clinical translation in near future.