Polarization of Tumor-Associated Macrophages by Nanoparticle-Loaded Escherichia coli Combined with Immunogenic Cell Death for Cancer Immunotherapy

An all-in-one PEGylated NIR-II conjugated polymer for high-resolution blood circulation imaging and photothermal immunotherapy

Fluorescence imaging in the second near-infrared window (NIR-II) has shown tremendous potential for in vivo monitoring of biological processes, offering high spatial resolution and real-time imaging capabilities. Conjugated polymers, commonly used as photothermal agents (PTAs) in photothermal therapy, have emerged as promising candidates for NIR-II imaging. However, their imaging efficiency is compromised by aggregation, which arises from strong π-π stacking interactions between their extended π-conjugated backbones. In this work, we designed a novel conjugated polymer (CP) and developed an integrated nanoplatform (CPN-PEGnk, n = 2 or 5) through PEGylation. Notably, CPN-PEG5k exhibited a red-shift in NIR absorption along with a marked increase in NIR-II fluorescence intensity (2.97 folds greater) compared to physically encapsulated nanoparticles (F127@CPN). Furthermore, CPN-PEG5k retained a remarkable photothermal conversion efficiency of up to 58.6%. The exceptional NIR-II imaging performance of CPN-PEG5k was validated in detailed blood circulation imaging in mice, with a signal-to-background ratio of 8.9. In addition, in a breast cancer mouse model, CPN-PEG5k successfully eradicated tumors and stimulated immune responses, effectively suppressing tumor progression and metastasis. These findings underscore the potential of CPN-PEG5k in advancing conjugated polymer applications for NIR-II imaging.

Escherichia coli combination with PD-1 blockade synergistically enhances immunotherapy in glioblastoma multiforme by regulating the immune cells

BACKGROUND

Glioblastoma multiforme (GBM) is the most common and aggressive primary intracranial malignancy. It is characterized by insufficient infiltration of anti-tumor T lymphocytes within the tumor microenvironment (TME), rendering it an "immune cold" disease. This immune deficiency results in poor responses to immune checkpoint blockade (ICB) therapies. Recent studies have demonstrated that bacteria can proliferate within tumors and activate immune responses. Therefore, in this study, we employed Escherichia coli (E. coli) in combination with anti-PD-1 antibodies to treat GBM, with the aim of exploring the immune-activating potential of E. coli in GBM and its synergistic effect on anti-PD-1 therapy.

METHODS

The E. coli and anti-PD-1 antibody therapy were administered intravenously and intraperitoneally, respectively. Complete blood cell count, blood biochemical analysis, hematoxylin and eosin (H&E) staining, and agar plate culture were employed to evaluate the biosafety and tumor-targeting capability of E. coli. ELISA kits were used to detect innate immune cytokines. Flow cytometry and immunofluorescence staining were used to investigate T cells. Tumor volume of tumor-bearing mice was recorded to evaluate the combined treatment efficacy. H&E staining and immunofluorescence staining were used to observe the tumor inhibition markers.

RESULTS

E.coli can specifically target into the tumor region, and activate the innate immune response in mice. Immunofluorescence staining and flow cytometry results demonstrated that the combination treatment group exhibited a significant upregulation of cytotoxic CD8+ T cells and a marked suppression of regulatory T cells compared to the control group. The expression of Ki67 was significantly downregulated, and TUNEL staining revealed an increased number of apoptotic cells in the combination treatment group. Furthermore, the tumor growth rate in the combination treatment group was significantly slower than that in the control group.

CONCLUSIONS

E. coli exhibits potential anti-tumor activity and can activate the innate immune response and further regulate immune cells in the tumor tissues to synergize the effect of anti-PD-1 therapy on GBM, providing new insights to enhance the efficacy of GBM immunotherapy.

Overcoming hypoxia-induced breast cancer drug resistance: a novel strategy using hollow gold-platinum bimetallic nanoshells

Breast cancer (BC) is a significant cause of cancer-related deaths among women worldwide. Hypoxia, a common feature of solid tumor, is associated with drug resistance and a poor prognosis in BC. In this study, we present a strategy to overcome hypoxia-induced chemotherapy tolerance in BC. Specifically, we synthesized a hollow gold (Au)-platinum (Pt) bimetallic nanoshell for the first time, which acted as a drug delivery system (DDS) for doxorubicin (DOX). The photothermal effect, induced by the surface plasmon resonance (SPR) from the Au-Pt shell under near infrared-II (NIR-II) laser irradiation, not only directly causes tumor cell death through photothermal therapy (PTT), but also significantly enhances the catalase-like activity between Pt nanoparticles and endogenous H2O2. This, subsequently, results in a heightened yield of O2, which further facilitates the release of DOX. This process alleviates tumor hypoxia and down-regulating hypoxia-inducible factor-1α (HIF-1α), multidrug resistance gene 1 (MDR1), and P-glycoprotein (P-gp), which can reverse drug resistance and achieve more effective DOX chemotherapy effects. Significantly, the increased availability of oxygen further re-polarizes immunosuppressive M2 macrophages into antitumor M1 macrophages. This study presents a novel strategy to tackle tumor proliferation and enhance tumor response to chemotherapy, offering hope for reversing in drug resistance in cancerous lesions.

A Self-Cascading Catalytic Therapy and Antigen Capture Scaffold-Mediated T Cells Augments for Postoperative Brain Immunotherapy

The recruitment of T lymphocytes holds great potential for suppressing the most aggressive glioblastoma (GBM) recurrence with immunotherapy. However, the phenomenon of immune privilege and the generally low immunogenicity of vaccines often reduce the presence of lymphocytes within brain tumors, especially in brain tumor recurrence clusters. In this study, an implantable self-cascading catalytic therapy and antigen capture scaffold (CAS) that can boost catalytic therapy efficiency at post-surgery brain tumor and capture the antigens via urethane-polyethylene glycol-polypropylene glycol (PU-EO-PO) segments are developed for postoperative brain immunotherapy. The CAS consists of 3D-printed elastomers modified with iron (Fe2+) metal-organic frameworks (MOFs, MIL88) and acts as a programmed peroxide mimic in cancer cells to initiate the Fenton reaction and sustain ROS production. With the assistance of chloroquine (CQ), autophagy is inhibited through lysosome deacidification, which interrupts the self-defense mechanism, further enhances cytotoxicity, and releases antigens. Then, CAS containing PU-EO-PO groups acts as an antigen depot to detain autologous tumor-associated antigens to dendritic cells maturation and T cell augments for sustained immune stimulation. CAS enhanced the immune response to postoperative brain tumors and improved survival through brain immunotherapy.

Cocktail strategy-based nanomedicine: A synergistic cascade of starvation, NIR-II photothermal, and gas therapy for enhanced tumor immunotherapy

Immunotherapy has emerged as a highly promising strategy in the realm of cancer treatment, wherein immunogenic cell death (ICD) is considered a potential trigger for anti-tumor immunity by inducing adaptive immunity to dying cell antigens. This process is often accompanied by the exposure, active secretion, or passive release of a large number of damage-associated molecular patterns (DAMPs), which activate dendritic cells (DCs) and enhance their antigen-presenting capacity. Subsequently, it promotes the recruitment and activation of cytotoxic T lymphocytes, ultimately leading to tumor growth inhibition. In addition, polarizing the M2 phenotype of tumor-associated macrophages (TAMs) to the M1 phenotype is another way to activate anti-tumor immunity, which can further enhance the effect of anti-tumor immunotherapy. In this study, we engineered a composite nanoparticle of UiO-66-NH2@Gold nanoshells@GOx-P-Arg (denoted as UGsGP). The gold nano shells in UGsGP exhibit a broad Near-Infrared-II (NIR-II) absorption to give a high photothermal conversion efficiency and achieve photothermal therapy (PTT). The GOx in UGsGP involves the breakdown of glucose, which results in a decrease in ATP levels and an inhibition of HSP90 and HSP70 production, ultimately enhancing the heat sensitivity of the tumor for PTT. In addition, GOx-mediated starvation therapy by glucose exhaustion produces a substantial amount of hydrogen peroxide (H2O2), which can then react with P-Arg to produce intratumoral NO Thus, the synergistic effect of PTT resensitization, the photothermally-enhanced GOx-mediated starvation, and NO-based gas therapy promote the induction of ICD and the polarization of TAMs. The combination therapy exhibits significant antitumor effects both in vitro and in vivo. STATEMENT OF SIGNIFICANCE: (1) Gold nanoshells on the surface of UiO-66-NH2 display a broad absorption spectrum ranging from 900 to 1700 nm, combined with a high photothermal conversion efficiency of 74.0 %, demonstrating their remarkable ability to harness and convert light energy into heat for effective tumor ablation. (2) Under laser irradiation, GOx within the UGsGPs effectively consumes glucose, increasing intratumoral H2O2 levels, which then reacts with P-Arg to produce NO within the tumor. Concurrently, the reduction in ATP levels suppresses HSP90 and HSP70 production, thereby enhancing the tumor's sensitivity to photothermal therapy. (3) The synergistic combination of NO gas therapy, starvation therapy, and PTT promotes ICD induction and TAM polarization, thereby improving the therapeutic outcomes for primary and distant tumors.

NIR responsive nanosystem based on upconversion nanoparticle-engineered bacteria for immune/photodynamic combined therapy with bacteria self-clearing capability

Biological engineering bacteria hold great promise in tumor therapy due to their targeted delivery, tumor penetration, and tumor-specific activation capabilities. However, the use of live bacteria raises safety concerns, as they can potentially cause infections or adverse immune responses in patients. Additionally, most biological engineering bacteria are only responsive to blue light, which has limited penetration depth within biological tissues. To address these limitations, we have developed a nanoplatform that combines dual-emission upconversion nanoparticles (referred to as DDUCNPs), which can realize dual-wavelength emission under dual-wavelength excitation, with biological engineering bacteria for tumor treatment and the self-clearance of biological engineering bacteria after therapy in the near-infrared (NIR) window. This design allows us to utilize 980 nm light, which is converted to blue light by the DDUCNPs, to activate the bacteria and promote the controlled release of tumor necrosis factor-alpha (TNF-α) for precise tumor ablation. Subsequently, we employ 808 nm excitation to achieve light conversion into the red light, thereby activating photosensitizer molecules and generating singlet oxygen (ROS) for in vivo clearance of the bacteria involved in the treatment. Simultaneously, the generated ROS also undergoes photodynamic therapy (PDT) on the tumor to enhance the therapeutic effect. By combining these elements on a single platform, our system achieves the activation and self-clearance of biological engineering bacteria in the NIR window, effectively enabling tumor treatment. This approach overcomes the limitations of blue light penetration and addresses safety concerns associated with live bacteria, offering a promising strategy for precise and controlled tumor therapy.

NIR-Activated Hydrogel with Dual-Enhanced Antibiotic Effectiveness for Thorough Elimination of Antibiotic-Resistant Bacteria

Antibiotic resistance has become a critical health crisis globally. Traditional strategies using antibiotics can lead to drug-resistance, while inorganic antimicrobial agents can cause severe systemic toxicity. Here, we have developed a dual-antibiotic hydrogel delivery system (PDA-Ag@Levo/CMCS), which can achieve controlled release of clinical antibiotics levofloxacin (Levo) and classic nanoscale antibiotic silver nanoparticles (AgNPs), effectively eliminating drug-resistant P. aeruginosa. Benefiting from the photothermal (PTT) effect of polydopamine (PDA), the local high temperature generated by PDA-Ag@Levo/CMCS can quickly kill bacteria through continuous and responsive release of dual-antibiotics to restore sensitivity to ineffective antibiotics. Moreover, AgNPs could significantly improve the efficiency of traditional antibiotics by disrupting bacterial membranes and reducing their toxicity to healthy tissues. A clever combination of PTT and drug-combination therapy can effectively eliminate biofilms and drug-resistant bacteria. Mechanism studies have shown that PDA-Ag@Levo might eliminate drug-resistant P. aeruginosa by disrupting biofilm formation and protein synthesis, and inhibit the resistance mutation of P. aeruginosa by promoting the expression of related genes, such as rpoS, dinB, and mutS. Collectively, the synergistic effect of this dual-antibiotic hydrogel combined with PTT provides a creative strategy for eliminating drug-resistant bacteria in chronic infection wounds.

Tumor microenvironment immunomodulation by nanoformulated TLR 7/8 agonist and PI3k delta inhibitor enhances therapeutic benefits of radiotherapy

Infiltration of immunosuppressive cells into the breast tumor microenvironment (TME) is associated with suppressed effector T cell (Teff) responses, accelerated tumor growth, and poor clinical outcomes. Previous studies from our group and others identified infiltration of immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) as critical contributors to immune dysfunction in the orthotopic claudin-low tumor model, limiting the efficacy of adoptive cellular therapy. However, approaches to target these cells in the TME are currently lacking. To overcome this barrier, polymeric micellular nanoparticles (PMNPs) were used for the co-delivery of small molecule drugs activating Toll-like receptors 7 and 8 (TLR7/8) and inhibiting PI3K delta (PI3Kδ). The immunomodulation of the TME by TLR7/8 agonist and PI3K inhibitor led to type 1 macrophage polarization, decreased MDSC accumulation and selectively decreased tissue-resident Tregs in the TME, while enhancing the T and B cell adaptive immune responses. PMNPs significantly enhanced the anti-tumor activity of local radiation therapy (RT) in mice bearing orthotopic claudin-low tumors compared to RT alone. Taken together, these data demonstrate that RT combined with a nanoformulated immunostimulant diminished the immunosuppressive TME resulting in tumor regression. These findings set the stage for clinical studies of this approach.

A Multisynergistic Strategy for Bone Tumor Treatment: Orchestrating Oxidative Stress and Autophagic Flux Inhibition by Environmental-Response Nanoparticle

Tumor therapy has advanced significantly in recent years, but tumor cells can still evade and survive the treatment through various mechanisms. Notably, tumor cells use autophagy to sustain viability by removing impaired mitochondria and clearing excess reactive oxygen species (ROS). In this study, the aim is to amplify intracellular oxidative stress by inhibiting mitochondrial autophagic flux. Multisynergistic environmental-response nanoparticles (ERNs) are engineered by integrating gold nanoparticles and copper peroxide with borosilicate bioactive glass. The controlled release of copper and inhibition of autophagy flux triggered an overabundance and accumulation of oxidative stress within the tumor cells. This stress triggered immunogenic tumor cell death, believed to initiate a systemic immune response. The tumor microenvironment (TME) transitioned back to a normal physiological state as tumor cells are ablated. ERNs responded to the microenvironment changes by depositing hydroxyapatite on the surface and spontaneously enhancing bone regeneration. This innovative formulation facilitates the functional transition of ERNs from "anti-tumor therapy" to "biomineralization" that kills cancers and induces new bone formation. Overall, it is shown that the ERNs effectively eradicate cancers by utilizing chemodynamic therapy, starvation therapy, and immunotherapy.

Nano-Armed Limosilactobacillus reuteri for Enhanced Photo-Immunotherapy and Microbiota Tryptophan Metabolism against Colorectal Cancer

Despite being a groundbreaking approach to treating colorectal cancer (CRC), the efficacy of immunotherapy is significantly compromised by the immunosuppressive tumor microenvironment and dysbiotic intestinal microbiota. Here, leveraging the superior carrying capacity and innate immunity-stimulating property of living bacteria, a nanomedicine-engineered bacterium, LR-S-CD/CpG@LNP, with optical responsiveness, immune-stimulating activity, and the ability to regulate microbiota metabolome is developed. Immunoadjuvant (CpG) and carbon dot (CD) co-loaded plant lipid nanoparticles (CD/CpG@LNPs) are constructed and conjugated to the surface of Limosilactobacillus reuteri (LR) via reactive oxygen species (ROS)-responsive linkers. The inherent photothermal and photodynamic properties of oral CD/CpG@LNPs induce in situ cytotoxic ROS generation and immunogenic cell death of colorectal tumor cells. The generated neoantigens and the released CpG function as a potent in situ vaccine that stimulates the maturation of immature dendritic cells. The mature dendritic cells and metabolites secreted by LR subsequently facilitated the tumor infiltration of cytotoxic T lymphocytes to eradicate colorectal tumors. The further in vivo results demonstrate that the photo-immunotherapy and intestinal microbial metabolite regulation of LR-S-CD/CpG@LNPs collectively suppressed the growth of orthotopic colorectal tumors and their liver metastases, presenting a promising avenue for synergistic treatment of CRC via the oral route.

Bimodal accurate H2O2 regulation to equalize tumor-associated macrophage repolarization and immunogenic tumor cell death elicitation

Simultaneous implementation of tumor-associated macrophage (TAM) repolarization and immunogenic tumor cell death (ICD) elicitation enables tumor immunotherapy with high efficacy. However, the inconsistency of stimulation tolerance restricts simultaneous implementation. To address this obstacle, we validate that an H2O2-mediated regulatory strategy could achieve coordinated occurrences. To accomplish this, a bimodal responsive modulator is constructed, namely ZnO2-ATM (ATM: 3-amino-1,2,4-triazole), as an immune adjuvant to coordinate the occurrence of TAM repolarization and ICD elicitation through the endo/exogenous synergistic responsive production of H2O2. H2O2 produced by ZnO2-ATM reverses the immune-suppressive TAM from an M2 to an M1 phenotype, but induces tumor cell necrosis and promotes damage-related molecular pattern release, thereby evoking ICD. This H2O2-mediation bimodal responsive therapeutic strategy to induce the synergistic occurrence of TAM repolarization and ICD elicitation promotes effective immune effects against tumors, demonstrating that the ZnO2-ATM nanoadjuvant could be expected to provide new tools and paradigms for antitumor immunotherapy.

Nanomedicine based on chemotherapy-induced immunogenic death combined with immunotherapy to enhance antitumor immunity

Introduction

Chemo-immunotherapy based on inducing tumor immunogenic cell death (ICD)with chemotherapy drugs has filled the gaps between traditional chemotherapy and immunotherapy. It is verified that paclitaxel (PTX) can induce breast tumor ICD. From this basis, a kind of nanoparticle that can efficiently deliver different drug components simultaneously is constructed. The purpose of this study is for the sake of exploring the scheme of chemotherapy-induced ICD combined with other immunotherapy to enhance tumor immunogenicity and inhibit the growth, metastasis, and recurrence of breast tumors, so as to provide a research basis for solving the tough problem of breast cancer treatment.

Methods

Nanomedicine loaded with PTX, small interference RNA that suppresses CD47 expression (CD47siRNA, siCD47), and immunomodulator R848 were prepared by the double emulsification method. The hydrodynamic diameter and zeta potential of NP/PTX/siCD47/R848 were characterized. Established the tumor-bearing mice model of mouse breast cancer cell line (4T1) in situ and observed the effect of intravenous injection of NP/PTX/siCD47/R848 on the growth of 4T1 tumor in situ. Flow cytometry was used to detect the effect of drugs on tumor immune cells.

Results

NP/PTX/siCD47/R848 nano-drug with tumor therapeutic potential were successfully prepared by double emulsification method, with particle size of 121.5 ± 4.5 nm and surface potential of 36.1 ± 2.5 mV. The calreticulin on the surface of cell membrane and extracellular ATP or HMGB1 of 4T1 cells increased through treatment with NPs. NP/PTX-treated tumor cells could cause activation of BMDCs and BMDMs. After intravenous injection, NP/PTX could quickly reach the tumor site and accumulate for 24 h. The weight and volume of tumor in situ in the breast cancer model mice injected with nanomedicine through the tail vein were significantly lower than those in the PBS group. The ratio of CD8+/CD4+ T cells in the tumor microenvironment and the percentage of dendritic cells in peripheral blood increased significantly in breast cancer model mice injected with nano-drugs through the tail vein.

Discussion

Briefly, the chemotherapeutic drug paclitaxel can induce breast cancer to induce ICD. The nanomedicine which can deliver PTX, CD47siRNA, and R848 at the same time was prepared by double emulsification. NP/PTX/siCD47/R848 nano-drug can be enriched in the tumor site. The experiment of 4T1 cell tumor-bearing mice shows that the nano-drug can enhance tumor immunogenicity and inhibit breast tumor growth, which provides a new scheme for breast cancer treatment. (Graphical abstract).

Nanoengineered Endocytic Biomaterials for Stem Cell Therapy

Stem cells, ideal for the tissue repair and regeneration, possess extraordinary capabilities of multidirectional differentiation and self‐renewal. However, the limited spontaneous differentiation potential makes it challenging to harness them for tissue repair without external intervention. Although conventional approaches using biomolecules, small organic molecules, and ions have shown specific and effective functions, they face challenges such as in vivo diffusion and degradation, poor internalization, and side effects on adjacent cells. Nanoengineered biomaterials offer a solution by solidifying and nanosizing these soluble regulating molecules and ions, facilitating their uptake by stem cells. Once inside lysosomes, these nanoparticles release their contents in a controlled “molecule or ion storm,” efficiently altering the intracellular biological and chemical microenvironment to tune the differentiation of stem cells. This newly emerged approach for regulating stem cell fate has attracted much attention in recent years. This method has shown promising results and is poised to enhance clinical stem cell therapy. This review provides an overview of the design principles for nanoengineered biomaterials, discusses the categories and characteristics of nanoparticles, summarizes the application of nanoparticles in tissue repair and regeneration, and discusses the direction of nanoparticle‐enhanced stem cell therapy and prospects for its clinical application in regenerative medicine.

Dual-Functional Nanodroplet for Tumor Vasculature Ultrasound Imaging and Tumor Immunosuppressive Microenvironment Remodeling

Accurately evaluating tumor neoangiogenesis and conducting precise interventions toward an immune-favorable microenvironment are of significant clinical importance. In this study, a novel nanodroplet termed as the nanodroplet-based ultrasound contrast agent and therapeutic (NDsUCA/Tx) is designed for ultrasound imaging and precise interventions of tumor neoangiogenesis. Briefly, the NDsUCA/Tx shell is constructed from an engineered CMs containing the tumor antigen, vascular endothelial growth factor receptor 1 (VEGFR1) extracellular domain 2-3, and CD93 ligand multimerin 2. The core is composed of perfluorohexane and the immune adjuvant R848. After injection, NDsUCA/Tx is found to be enriched in the tumor vasculature with high expression of CD93. When triggered by ultrasound, the perfluorohexane in NDsUCA/Tx underwent acoustic droplet vaporization and generated an enhanced ultrasound signal. Some microbubbles exploded and the resultant debris (with tumor antigen and R848) together with the adsorbed VEGF are taken up by nearby cells. This cleared the local VEGF for vascular normalization, and also served as a vaccine to activate the immune response. Using a syngeneic mouse model, the satisfactory performance of NDsUCA/Tx in tumor vasculature imaging and immune activation is confirmed. Thus, a multifunctional NDsUCA/Tx is successfully developed for molecular imaging of tumor neoangiogenesis and precise remodeling of the tumor microenvironment.

Targeted intervention in nerve-cancer crosstalk enhances pancreatic cancer chemotherapy

Nerve-cancer crosstalk has gained substantial attention owing to its impact on tumour growth, metastasis and therapy resistance. Effective therapeutic strategies targeting tumour-associated nerves within the intricate tumour microenvironment remain a major challenge in pancreatic cancer. Here we develop Escherichia coli Nissle 1917-derived outer membrane vesicles conjugated with nerve-binding peptide NP41, loaded with the tropomyosin receptor kinase (Trk) inhibitor larotrectinib (Lar@NP-OMVs) for tumour-associated nerve targeting. Lar@NP-OMVs achieve efficient nerve intervention to diminish neurite growth by disrupting the neurotrophin/Trk signalling pathway. Moreover, OMV-mediated repolarization of M2-like tumour-associated macrophages to an M1-like phenotype results in nerve injury, further accentuating Lar@NP-OMV-induced nerve intervention to inhibit nerve-triggered proliferation and migration of pancreatic cancer cells and angiogenesis. Leveraging this strategy, Lar@NP-OMVs significantly reduce nerve infiltration and neurite growth promoted by gemcitabine within the tumour microenvironment, leading to augmented chemotherapy efficacy in pancreatic cancer. This study sheds light on a potential avenue for nerve-targeted therapeutic intervention for enhancing pancreatic cancer therapy.

The Rational Engineered Bacteria Based Biohybrid Living System for Tumor Therapy

Living therapy based on bacterial cells has gained increasing attention for their applications in tumor treatments. Bacterial cells can naturally target to tumor sites and active the innate immunological responses. The intrinsic advantages of bacteria attribute to the development of biohybrid living carriers for targeting delivery toward hypoxic environments. The rationally engineered bacterial cells integrate various functions to enhance the tumor therapy and reduce toxic side effects. In this review, the antitumor effects of bacteria and their application are discussed as living therapeutic agents across multiple antitumor platforms. The various kinds of bacteria used for cancer therapy are first introduced and demonstrated the mechanism of antitumor effects as well as the immunological effects. Additionally, this study focused on the genetically modified bacteria for the production of antitumor agents as living delivery system to treat cancer. The combination of living bacterial cells with functional nanomaterials is then discussed in the cancer treatments. In brief, the rational design of living therapy based on bacterial cells highlighted a rapid development in tumor therapy and pointed out the potentials in clinical applications.

In situ formed reactive oxygen species-responsive dipyridamole prodrug hydrogel: Spatiotemporal drug delivery for chemoimmunotherapy

In the realm of combined cancer immunotherapy, the strategic combination of therapeutics targeting both cancer cells and macrophages holds immense potential. However, the major challenges remain on how to achieve facile spatiotemporal delivery of these therapies, allowing ease of manipulation and ensuring differential drug release for enhanced synergistic therapeutic effects. In the present study, we introduced a tumor microenvironment (TME)-adapted hydrogel with the phenylboronic acid-modified dipyridamole prodrug (DIPP) as a crosslinker. This prodrug hydrogel scaffold, 3BP@DIPPGel, could be formed in situ by a simple mixture of DIPP and poly(vinyl alcohol) (PVA), and loaded with a high ratio of 3-bromopyruvic acid (3BP). The 3BP@DIPPGel enables spatiotemporal localized delivery of dipyridamole (DIP) and 3BP with distinct release kinetics that effectively reshape the immunosuppressive TME. Upon reactive oxygen species (ROS) stimulation, 3BP@DIPPGel preferentially released 3BP, inducing tumor-specific pyroptosis via the ROS/BAX/caspase-3/GSDME signaling pathway and decreasing the secretion of chemokines such as CCL8 to counteract macrophage recruitment. Subsequently, the crosslinked DIP is released, triggering the tumor-associated macrophages (TAMs) polarization towards the immunostimulatory M1 phenotype via the CCR2/JAK2/STAT3 cascade signaling pathway. This dual action from 3BP@DIPPGel leads to the restoration of tumor cell immunogenicity with high efficacy and activation of immune cells. Furthermore, the 3BP@DIPPGel-based chemoimmunotherapy upregulates the expression of sialic-acid-binding Ig-like lectin 10 and hence sensitizing tumors to anti-CD24 therapy in the tumor-bearing mice. Therefore, this strategy can have significant potential in the prevention of tumor metastases and recurrence. To the best of our understanding, this study represents a pioneering showcase of tumor pyroptosis, induced by glycolytic inhibitors, which can be effectively coordinated with DIP-mediated TAM polarization for immune activation, offering a new paradigm for differentially sustained drug delivery to foster cancer immunotherapy.

Research progress of tumor-associated macrophages in immune checkpoint inhibitor tolerance in colorectal cancer

The relevant mechanism of tumor-associated macrophages (TAMs) in the treatment of colorectal cancer patients with immune checkpoint inhibitors (ICIs) is discussed, and the application prospects of TAMs in reversing the treatment tolerance of ICIs are discussed to provide a reference for related studies. As a class of drugs widely used in clinical tumor immunotherapy, ICIs can act on regulatory molecules on cells that play an inhibitory role-immune checkpoints-and kill tumors in the form of an immune response by activating a variety of immune cells in the immune system. The sensitivity of patients with different types of colorectal cancer to ICI treatment varies greatly. The phenotype and function of TAMs in the colorectal cancer microenvironment are closely related to the efficacy of ICIs. ICIs can regulate the phenotypic function of TAMs, and TAMs can also affect the tolerance of colorectal cancer to ICI therapy. TAMs play an important role in ICI resistance, and making full use of this target as a therapeutic strategy is expected to improve the immunotherapy efficacy and prognosis of patients with colorectal cancer.

Nanomaterial combined engineered bacteria for intelligent tumor immunotherapy

Cancer remains the leading cause of human death worldwide. Compared to traditional therapies, tumor immunotherapy has received a lot of attention and research focus due to its potential to activate both innate and adaptive immunity, low toxicity to normal tissue, and long-term immune activity. However, its clinical effectiveness and large-scale application are limited due to the immunosuppression microenvironment, lack of spatiotemporal control, expensive cost, and long manufacturing time. Recently, nanomaterial combined engineered bacteria have emerged as a promising solution to the challenges of tumor immunotherapy, which offers spatiotemporal control, reversal of immunosuppression, and scalable production. Therefore, we summarize the latest research on nanomaterial-assisted engineered bacteria for precise tumor immunotherapies, including the cross-talk of nanomaterials and bacteria as well as their application in different immunotherapies. In addition, we further discuss the advantages and challenges of nanomaterial-engineered bacteria and their future prospects, inspiring more novel and intelligent tumor immunotherapy.

Paclitaxel Prodrug Enables Glutathione Depletion to Boost Cancer Treatment

Herein, we constructed a paclitaxel (PTX) prodrug (PA) by conjugating PTX with acrylic acid as a cysteine-depleting agent. The as-synthesized PA can assemble with diacylphosphatidylethanolamine-PEG2000 to form stable nanoparticles (PA NPs). After endocytosis into cells, PA NPs can specifically react with cysteine and trigger release of PTX for chemotherapy. On the other hand, the depletion of cysteine can greatly downregulate the intracellular content of glutathione and lead to oxidative stress outburst-provoking ferroptosis. The released PTX can elicit antitumor immune response by inducing immunogenic cell death, thus promoting dendritic cells maturation and cascaded cytotoxic T lymphocytes activation, which not only produces a robust immunotherapy effect but also synergizes the ferroptosis therapy by inhibiting cysteine transport via the release of interferon-γ in the activated immune system. As a result, PA NPs exhibit favorable in vitro and in vivo antitumor performance with reduced systemic toxicity. Our work highlights the potential of simple molecular design of prodrugs for enhancing the therapeutic efficacy toward malignant cancer.

Interference of ATP-Adenosine Axis by Engineered Biohybrid for Amplifying Immunogenic Cell Death-Mediated Antitumor Immunotherapy

Immunogenic cell death (ICD) often results in the production and accumulation of adenosine (ADO), a byproduct that negatively impacts the therapeutic effect as well as facilitates tumor development and metastasis. Here, an innovative strategy is elaborately developed to effectively activate ICD while avoiding the generation of immunosuppressive adenosine. Specifically, ZIF-90, an ATP-responsive consumer, is synthesized as the core carrier to encapsulate AB680 (CD73 inhibitor) and then coated with an iron-polyphenol layer to prepare the ICD inducer (AZTF), which is further grafted onto prebiotic bacteria via the esterification reaction to obtain the engineered biohybrid (Bc@AZTF). Particularly, the designed Bc@AZTF can actively enrich in tumor sites and respond to the acidic tumor microenvironment to offload AZTF nanoparticles, which can consume intracellular ATP (iATP) content and simultaneously inhibit the ATP-adenosine axis to reduce the accumulation of adenosine, thereby alleviating adenosine-mediated immunosuppression and strikingly amplifying ICD effect. Importantly, the synergy of anti-PD-1 (αPD-1) with Bc@AZTF not only establishes a collaborative antitumor immune network to potentiate effective tumoricidal immunity but also activates long-lasting immune memory effects to manage tumor recurrence and rechallenge, presenting a new paradigm for ICD treatment combined with adenosine metabolism.

Recent Progress on Nanomedicine-Mediated Repolarization of Tumor-Associated Macrophages for Cancer Immunotherapy

Tumor-associated macrophages (TAMs) constitute the largest number of immune cells in the tumor microenvironment (TME). They play an essential role in promoting tumor progression and metastasis, which makes them a potential therapeutic target for cancer treatment. TAMs are usually divided into two categories: pro-tumoral M2-like TAMs and antitumoral M1 phenotypes at either extreme. The reprogramming of M2-like TAMs toward a tumoricidal M1 phenotype is of particular interest for the restoration of antitumor immunity in cancer immunotherapy. Notably, nanomedicines have shown great potential for cancer therapy due to their unique structures and properties. This review will briefly describe the biological features and roles of TAMs in tumor, and then discuss recent advances in nanomedicine-mediated repolarization of TAMs for cancer immunotherapy. Finally, perspectives on nanomedicine-mediated repolarization of TAMs for effective cancer immunotherapy are also presented.

The long-term effectiveness and mechanism of oncolytic virotherapy combined with anti-PD-L1 antibody in colorectal cancer patient

Colorectal cancer (CRC) is known to be resistant to immunotherapy. In our phase-I clinical trial, one patient achieved a 313-day prolonged response during the combined treatment of oncolytic virotherapy and immunotherapy. To gain a deeper understanding of the potential molecular mechanisms, we performed a comprehensive multi-omics analysis on this patient and three non-responders. Our investigation unveiled that, initially, the tumor microenvironment (TME) of this responder presented minimal infiltration of T cells and natural killer cells, along with a relatively higher presence of macrophages compared to non-responders. Remarkably, during treatment, there was a progressive increase in CD4+ T cells, CD8+ T cells, and B cells in the responder's tumor tissue. This was accompanied by a significant upregulation of transcription factors associated with T-cell activation and cytotoxicity, including GATA3, EOMES, and RUNX3. Furthermore, dynamic monitoring of peripheral blood samples from the responder revealed a rapid decrease in circulating tumor DNA (ctDNA), suggesting its potential as an early blood biomarker of treatment efficacy. Collectively, our findings demonstrate the effectiveness of combined oncolytic virotherapy and immunotherapy in certain CRC patients and provide molecular evidence that virotherapy can potentially transform a "cold" TME into a "hot" one, thereby improving sensitivity to immunotherapy.

Advances in Nanomaterials for Immunotherapeutic Improvement of Cancer Chemotherapy

Immuno-stimulative effect of chemotherapy (ISECT) is recognized as a potential alternative to conventional immunotherapies, however, the clinical application is constrained by its inefficiency. Metronomic chemotherapy, though designed to overcome these limitations, offers inconsistent results, with effectiveness varying based on cancer types, stages, and patient-specific factors. In parallel, a wealth of preclinical nanomaterials holds considerable promise for ISECT improvement by modulating the cancer-immunity cycle. In the area of biomedical nanomaterials, current literature reviews mainly concentrate on a specific category of nanomaterials and nanotechnological perspectives, while two essential issues are still lacking, i.e., a comprehensive analysis addressing the causes for ISECT inefficiency and a thorough summary elaborating the nanomaterials for ISECT improvement. This review thus aims to fill these gaps and catalyze further development in this field. For the first time, this review comprehensively discusses the causes of ISECT inefficiency. It then meticulously categorizes six types of nanomaterials for improving ISECT. Subsequently, practical strategies are further proposed for addressing inefficient ISECT, along with a detailed discussion on exemplary nanomedicines. Finally, this review provides insights into the challenges and perspectives for improving chemo-immunotherapy by innovations in nanomaterials.

Path to bacteriotherapy: From bacterial engineering to therapeutic perspectives

The major reason for the failure of conventional therapies is the heterogeneity and complexity of tumor microenvironments (TMEs). Many malignant tumors reprogram their surface antigens to evade the immune surveillance, leading to reduced antigen-presenting cells and hindered T-cell activation. Bacteria-mediated cancer immunotherapy has been extensively investigated in recent years. Scientists have ingeniously modified bacteria using synthetic biology and nanotechnology to enhance their biosafety with high tumor specificity, resulting in robust anticancer immune responses. To enhance the antitumor efficacy, therapeutic proteins, cytokines, nanoparticles, and chemotherapeutic drugs have been efficiently delivered using engineered bacteria. This review provides a comprehensive understanding of oncolytic bacterial therapies, covering bacterial design and the intricate interactions within TMEs. Additionally, it offers an in-depth comparison of the current techniques used for bacterial modification, both internally and externally, to maximize their therapeutic effectiveness. Finally, we outlined the challenges and opportunities ahead in the clinical application of oncolytic bacterial therapies.

Harnessing and Mimicking Bacterial Features to Combat Cancer: From Living Entities to Artificial Mimicking Systems

Bacterial-derived micro-/nanomedicine has garnered considerable attention in anticancer therapy, owing to the unique natural features of bacteria, including specific targeting ability, immunogenic benefits, physicochemical modifiability, and biotechnological editability. Besides, bacterial components have also been explored as promising drug delivery vehicles. Harnessing these bacterial features, cutting-edge physicochemical and biotechnologies have been applied to attenuated tumor-targeting bacteria with unique properties or functions for potent and effective cancer treatment, including strategies of gene-editing and genetic circuits. Further, the advent of bacteria-inspired micro-/nanorobots and mimicking artificial systems has furnished fresh perspectives for formulating strategies for developing highly efficient drug delivery systems. Focusing on the unique natural features and advantages of bacteria, this review delves into advances in bacteria-derived drug delivery systems for anticancer treatment in recent years, which has experienced a process from living entities to artificial mimicking systems. Meanwhile, a summary of relative clinical trials is provided and primary challenges impeding their clinical application are discussed. Furthermore, future directions are suggested for bacteria-derived systems to combat cancer.

Copper Deposition in Polydopamine Nanostructure to Promote Cuproptosis by Catalytically Inhibiting Copper Exporters of Tumor Cells for Cancer Immunotherapy

Cuproptosis is an emerging programmed cell death, displaying great potential in cancer treatment. However, intracellular copper content to induce cuproptosis is unmet, which mainly ascribes to the intracellular pumping out equilibrium mechanism by copper exporter ATP7A and ATP7B. Therefore, it is necessary to break such export balance mechanisms for desired cuproptosis. Mediated by diethyldithiocarbamate (DTC) coordination, herein a strategy to efficiently assemble copper ions into polydopamine nanostructure (PDA-DTC/Cu) for reprogramming copper metabolism of tumor is developed. The deposited Cu2+ can effectively trigger the aggregation of lipoylated proteins to induce cuproptosis of tumor cells. Beyond elevating intracellular copper accumulation, PDA-DTC/Cu enables to break the balance of copper metabolism by disrupting mitochondrial function and restricting the adenosine triphosphate (ATP) energy supply, thus catalytically inhibiting the expressions of ATP7A and ATP7B of tumor cells to enhance cuproptosis. Meanwhile, the killed tumor cells can induce immunogenic cell death (ICD) to stimulate the immune response. Besides, PDA-DTC/Cu NPs can promote the repolarization of tumor-associated macrophages (TAMs ) to relieve the tumor immunosuppressive microenvironment (TIME). Collectively, PDA-DTC/Cu presented a promising "one stone two birds" strategy to realize copper accumulation and inhibit copper export simultaneously to enhance cuproptosis for 4T1 murine breast cancer immunotherapy.

Nanomaterial-assisted oncolytic bacteria in solid tumor diagnosis and therapeutics

Cancer presents a formidable challenge in modern medicine due to the intratumoral heterogeneity and the dynamic microenvironmental niche. Natural or genetically engineered oncolytic bacteria have always been hailed by scientists for their intrinsic tumor-targeting and oncolytic capacities. However, the immunogenicity and low toxicity inevitably constrain their application in clinical practice. When nanomaterials, characterized by distinctive physicochemical properties, are integrated with oncolytic bacteria, they achieve mutually complementary advantages and construct efficient and safe nanobiohybrids. In this review, we initially analyze the merits and drawbacks of conventional tumor therapeutic approaches, followed by a detailed examination of the precise oncolysis mechanisms employed by oncolytic bacteria. Subsequently, we focus on harnessing nanomaterial-assisted oncolytic bacteria (NAOB) to augment the effectiveness of tumor therapy and utilizing them as nanotheranostic agents for imaging-guided tumor treatment. Finally, by summarizing and analyzing the current deficiencies of NAOB, this review provides some innovative directions for developing nanobiohybrids, intending to infuse novel research concepts into the realm of solid tumor therapy.

Advances in bacteria-based drug delivery systems for anti-tumor therapy

In recent years, bacteria have gained considerable attention as a promising drug carrier that is critical in improving the effectiveness and reducing the side effects of anti-tumor drugs. Drug carriers can be utilised in various forms, including magnetotactic bacteria, bacterial biohybrids, minicells, bacterial ghosts and bacterial spores. Additionally, functionalised and engineered bacteria obtained through gene engineering and surface modification could provide enhanced capabilities for drug delivery. This review summarises the current studies on bacteria-based drug delivery systems for anti-tumor therapy and discusses the prospects and challenges of bacteria as drug carriers. Furthermore, our findings aim to provide new directions and guidance for the research on bacteria-based drug systems.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Protein-assisted synthesis of chitosan-coated minicells enhance dendritic cell recruitment for therapeutic immunomodulation within pulmonary tumors

The efficacy of cancer therapies is significantly compromised by the immunosuppressive tumor milieu. Herein, we introduce a previously unidentified therapeutic strategy that harnesses the synergistic potential of chitosan-coated bacterial vesicles and a targeted chemotherapeutic agent to activate dendritic cells, thereby reshaping the immunosuppressive milieu for enhanced cancer therapy. Our study focuses on the protein-mediated modification of bacterium-derived minicells with chitosan molecules, facilitating the precise delivery of Doxorubicin to tumor sites guided by folate-mediated homing cues. These engineered minicells demonstrate remarkable specificity in targeting lung carcinomas, triggering immunogenic cell death and releasing tumor antigens and damage-associated molecular patterns, including calreticulin and high mobility group box 1. Additionally, the chitosan coating, coupled with bacterial DNA from the minicells, initiates the generation of reactive oxygen species and mitochondrial DNA release. These orchestrated events culminate in dendritic cell maturation via activation of the stimulator of interferon genes signaling pathway, resulting in the recruitment of CD4+ and CD8+ cytotoxic T cells and the secretion of interferon-β, interferon-γ, and interleukin-12. Consequently, this integrated approach disrupts the immunosuppressive tumor microenvironment, impeding tumor progression. By leveraging bacterial vesicles as potent dendritic cell activators, our strategy presents a promising paradigm for synergistic cancer treatment, seamlessly integrating chemotherapy and immunotherapy.

Engineered Microorganisms for Advancing Tumor Therapy

Engineered microorganisms have attracted significant interest as a unique therapeutic platform in tumor treatment. Compared with conventional cancer treatment strategies, engineering microorganism-based systems provide various distinct advantages, such as the intrinsic capability in targeting tumors, their inherent immunogenicity, in situ production of antitumor agents, and multiple synergistic functions to fight against tumors. Herein, the design, preparation, and application of the engineered microorganisms for advanced tumor therapy are thoroughly reviewed. This review presents a comprehensive survey of innovative tumor therapeutic strategies based on a series of representative engineered microorganisms, including bacteria, viruses, microalgae, and fungi. Specifically, it offers extensive analyses of the design principles, engineering strategies, and tumor therapeutic mechanisms, as well as the advantages and limitations of different engineered microorganism-based systems. Finally, the current challenges and future research prospects in this field, which can inspire new ideas for the design of creative tumor therapy paradigms utilizing engineered microorganisms and facilitate their clinical applications, are discussed.

Engineering nanomedicines for immunogenic eradication of cancer cells: Recent trends and synergistic approaches

Resistance to cancer immunotherapy is mainly attributed to poor tumor immunogenicity as well as the immunosuppressive tumor microenvironment (TME) leading to failure of immune response. Numerous therapeutic strategies including chemotherapy, radiotherapy, photodynamic, photothermal, magnetic, chemodynamic, sonodynamic and oncolytic therapy, have been developed to induce immunogenic cell death (ICD) of cancer cells and thereby elicit immunogenicity and boost the antitumor immune response. However, many challenges hamper the clinical application of ICD inducers resulting in modest immunogenic response. Here, we outline the current state of using nanomedicines for boosting ICD of cancer cells. Moreover, synergistic approaches used in combination with ICD inducing nanomedicines for remodeling the TME via targeting immune checkpoints, phagocytosis, macrophage polarization, tumor hypoxia, autophagy and stromal modulation to enhance immunogenicity of dying cancer cells were analyzed. We further highlight the emerging trends of using nanomaterials for triggering amplified ICD-mediated antitumor immune responses. Endoplasmic reticulum localized ICD, focused ultrasound hyperthermia, cell membrane camouflaged nanomedicines, amplified reactive oxygen species (ROS) generation, metallo-immunotherapy, ion modulators and engineered bacteria are among the most innovative approaches. Various challenges, merits and demerits of ICD inducer nanomedicines were also discussed with shedding light on the future role of this technology in improving the outcomes of cancer immunotherapy.

Image-Guided Photothermal and Immune Therapy of Tumors via Melanin-Producing Genetically Engineered Bacteria

Photothermal therapy (PTT) is a new treatment modality for tumors. However, the efficient delivery of photothermal agents into tumors remains difficult, especially in hypoxic tumor regions. In this study, an approach to deliver melanin, a natural photothermal agent, into tumors using genetically engineered bacteria for image-guided photothermal and immune therapy is developed. An Escherichia coli MG1655 is transformed with a recombinant plasmid harboring a tyrosinase gene to produce melanin nanoparticles. Melanin-producing genetically engineered bacteria (MG1655-M) are systemically administered to 4T1 tumor-bearing mice. The tumor-targeting properties of MG1655-M in the hypoxic environment integrate the properties of hypoxia targeting, photoacoustic imaging, and photothermal therapeutic agents in an "all-in-one" manner. This eliminates the need for post-modification to achieve image-guided hypoxia-targeted cancer photothermal therapy. Tumor growth is significantly suppressed by irradiating the tumor with an 808 nm laser. Furthermore, strong antitumor immunity is triggered by PTT, thereby producing long-term immune memory effects that effectively inhibit tumor metastasis and recurrence. This work proposes a new photothermal and immune therapy guided by an "all-in-one" melanin-producing genetically engineered bacteria, which can offer broad potential applications in cancer treatment.

Self-Assembled Nanoparticles from the Amphiphilic Prodrug of Resiquimod for Improved Cancer Immunotherapy

Tumor-associated macrophages (TAMs) usually adopt a tumor-promoting M2-like phenotype, which largely impedes the immune response and therapeutic efficacy of solid tumors. Repolarizing TAMs from M2 to the antitumor M1 phenotype is crucial for reshaping the tumor immunosuppressive microenvironment (TIME). Herein, we developed self-assembled nanoparticles from the polymeric prodrug of resiquimod (R848) to reprogram the TIME for robust cancer immunotherapy. The polymeric prodrug was constructed by conjugating the R848 derivative to terminal amino groups of the linear dendritic polymer composed of linear poly(ethylene glycol) and lysine dendrimer. The amphiphilic prodrug self-assembled into nanoparticles (PLRS) of around 35 nm with a spherical morphology. PLRS nanoparticles could be internalized by antigen-presenting cells (APCs) in vitro and thus efficiently repolarized macrophages from M2 to M1 and facilitated the maturation of APCs. In addition, PLRS significantly inhibited tumor growth in the 4T1 orthotopic breast cancer model with much lower systemic side effects. Mechanistic studies suggested that PLRS significantly stimulated the TIME by repolarizing TAMs into the M1 phenotype and increased the infiltration of cytotoxic T cells into the tumor. This study provides an effective polymeric prodrug-based strategy to improve the therapeutic efficacy of R848 in cancer immunotherapy.

Nanomaterials in modulating tumor-associated macrophages and enhancing immunotherapy

Tumor-associated macrophages (TAMs) are predominantly present in the tumor microenvironment (TME) and play a crucial role in shaping the efficacy of tumor immunotherapy. These TAMs primarily exhibit a tumor-promoting M2-like phenotype, which is associated with the suppression of immune responses and facilitation of tumor progression. Interestingly, recent research has highlighted the potential of repolarizing TAMs from an M2 to a pro-inflammatory M1 status-a shift that has shown promise in impeding tumor growth and enhancing immune responsiveness. This concept is particularly intriguing as it offers a new dimension to cancer therapy by targeting the tumor microenvironment, which is a significant departure from traditional approaches that focus solely on tumor cells. However, the clinical application of TAM-modulating agents is often challenged by issues such as insufficient tumor accumulation and off-target effects, limiting their effectiveness and safety. In this regard, nanomaterials have emerged as a novel solution. They serve a dual role: as delivery vehicles that can enhance the accumulation of therapeutic agents in the tumor site and as TAM-modulators. This dual functionality of nanomaterials is a significant advancement as it addresses the key limitations of current TAM-modulating strategies and opens up new avenues for more efficient and targeted therapies. This review provides a comprehensive overview of the latest mechanisms and strategies involving nanomaterials in modulating macrophage polarization within the TME. It delves into the intricate interactions between nanomaterials and macrophages, elucidating how these interactions can be exploited to drive macrophage polarization towards a phenotype that is more conducive to anti-tumor immunity. Additionally, the review explores the burgeoning field of TAM-associated nanomedicines in combination with tumor immunotherapy. This combination approach is particularly promising as it leverages the strengths of both nanomedicine and immunotherapy, potentially leading to synergistic effects in combating cancer.

Advances of Bacterial Biomaterials for Disease Therapy

Bacteria have immense potential as biological therapeutic agents that can be used to treat diseases, owing to their inherent immunomodulatory activity, targeting capabilities, and biosynthetic functions. The integration of synthetic biomaterials with natural bacteria has led to the construction of bacterial biomaterials with enhanced functionality and exceptional safety features. In this review, recent progress in the field of bacterial biomaterials, including bacterial drug delivery systems, bacterial drug-producing factories, bacterial biomaterials for metabolic engineering, bacterial biomaterials that can be remotely controlled, and living bacteria hydrogel formulations, is described and summarized. Furthermore, future trends in advancing next-generation bacterial biomaterials for enhanced clinical applications are proposed in the conclusion.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Engineered bacteria in tumor immunotherapy

As the limitations of cancer immunotherapy become increasingly apparent, there is considerable anticipation regarding the utilization of biological tools to enhance treatment efficacy, particularly bacteria and their derivatives. Leveraging advances in genetic and synthetic biology technologies, engineered bacteria now play important roles far beyond those of conventional immunoregulatory agents, and they could function as tumor-targeting vehicles and in situ pharmaceutical factories. In recent years, these engineered bacteria play a role in almost every aspect of immunotherapy. It is nothing short of impressive to keep seeing different strain of bacteria modified in diverse ways for unique immunological enhancement. In this review, we have scrutinized the intricate interplay between the immune system and these engineered bacteria. These interactions generate strategies that can directly or indirectly optimize immunotherapy and even modulate the effects of combination therapies. Collectively, these engineered bacteria present a promising novel therapeutic strategy that promises to change the current landscape of immunotherapy.

Free Radicals Generated in Perfluorocarbon-Water (Liquid-Liquid) Interfacial Contact Electrification and Their Application in Cancer Therapy

Electron transfer during solid-liquid contact electrification has been demonstrated to produce reactive oxygen species (ROS) such as hydroxyl radicals (•OH) and superoxide anion radicals (•O2-). Here, we show that such a process also occurs in liquid-liquid contact electrification. By preparing perfluorocarbon nanoemulsions to construct a perfluorocarbon-water "liquid-liquid" interface, we confirmed that electrons were transferred from water to perfluorocarbon in ultrasonication-induced high-frequency liquid-liquid contact to produce •OH and •O2-. The produced ROS could be applied to ablate tumors by triggering large-scale immunogenic cell death in tumor cells, promoting dendritic cell maturation and macrophage polarization, ultimately activating T cell-mediated antitumor immune response. Importantly, the raw material for producing •OH is water, so the tumor therapy is not limited by the endogenous substances (O2, H2O2, etc.) in the tumor microenvironment. This work provides new perspectives for elucidating the mechanism of generation of free radicals in liquid-liquid contact and provides an excellent tumor therapeutic modality.

Supramolecular Peptide Amphiphile Nanospheres Reprogram Tumor-associated Macrophage to Reshape the Immune Microenvironment for Enhanced Breast Cancer Immunotherapy

Tumor immunotherapy has become a research hotspot in cancer treatment, with macrophages playing a crucial role in tumor development. However, the tumor microenvironment restricts macrophage functionality, limiting their therapeutic potential. Therefore, modulating macrophage function and polarization is essential for enhancing tumor immunotherapy outcomes. Here, a supramolecular peptide amphiphile drug-delivery system (SPADS) is utilized to reprogram macrophages and reshape the tumor immune microenvironment (TIM) for immune-based therapies. The approach involved designing highly specific SPADS that selectively targets surface receptors of M2-type macrophages (M2-Mφ). These targeted peptides induced M2-Mφ repolarization into M1-type macrophages by dual inhibition of endoplasmic reticulum and oxidative stresses, resulting in improved macrophagic antitumor activity and immunoregulatory function. Additionally, TIM reshaping disrupted the immune evasion mechanisms employed by tumor cells, leading to increased infiltration, and activation of immune cells. Furthermore, the synergistic effect of macrophage reshaping and anti-PD-1 antibody (aPD-1) therapy significantly improved the immune system's ability to recognize and eliminate tumor cells, thereby enhancing tumor immunotherapy efficacy. SPADS utilization also induced lung metastasis suppression. Overall, this study demonstrates the potential of SPADS to drive macrophage reprogramming and reshape TIM, providing new insights, and directions for developing more effective immunotherapeutic approaches in cancer treatment.

Chimeric Peptide-Engineered Self-Delivery Nanomedicine for Photodynamic-Triggered Breast Cancer Immunotherapy by Macrophage Polarization

A systemic treatment strategy is urgently demanded to suppress the rapid growth and easy metastasis characteristics of breast cancer. In this work, a chimeric peptide-engineered self-delivery nanomedicine (designated as ChiP-CeR) for photodynamic-triggered breast cancer immunotherapy by macrophage polarization. Among these, ChiP-CeR is composed of the photosensitizer of chlorine e6 (Ce6) and the TLR7/8 agonist of lmiquimod (R837), which is further modified with tumor matrix targeting peptide (Fmoc-K(Fmoc)-PEG8-CREKA. ChiP-CeR is preferred to actively accumulate at the tumor site via specific recognition of fibronectin, which can eradicate primary tumor growth through photodynamic therapy (PDT). Meanwhile, the destruction of primary tumors would trigger immunogenic cell death (ICD) effects to release high-mobility group box-1(HMGB1) and expose calreticulin (CRT). Moreover, ChiP-CeR can also polarize M2-type tumor-associated macrophages (TAMs) into M1-type TAMs, which can activate T cell antitumor immunity in combination with ICD. Overall, ChiP-CeR possesses superior antitumor effects against primary and lung metastatic tumors, which provide an applicable nanomedicine and a feasible strategy for the systemic management of metastatic breast cancer.

Synergistic Brilliance: Engineered Bacteria and Nanomedicine Unite in Cancer Therapy

Engineered bacteria are widely used in cancer treatment because live facultative/obligate anaerobes can selectively proliferate at tumor sites and reach hypoxic regions, thereby causing nutritional competition, enhancing immune responses, and producing anticancer microbial agents in situ to suppress tumor growth. Despite the unique advantages of bacteria-based cancer biotherapy, the insufficient treatment efficiency limits its application in the complete ablation of malignant tumors. The combination of nanomedicine and engineered bacteria has attracted increasing attention owing to their striking synergistic effects in cancer treatment. Engineered bacteria that function as natural vehicles can effectively deliver nanomedicines to tumor sites. Moreover, bacteria provide an opportunity to enhance nanomedicines by modulating the TME and producing substrates to support nanomedicine-mediated anticancer reactions. Nanomedicine exhibits excellent optical, magnetic, acoustic, and catalytic properties, and plays an important role in promoting bacteria-mediated biotherapies. The synergistic anticancer effects of engineered bacteria and nanomedicines in cancer therapy are comprehensively summarized in this review. Attention is paid not only to the fabrication of nanobiohybrid composites, but also to the interpromotion mechanism between engineered bacteria and nanomedicine in cancer therapy. Additionally, recent advances in engineered bacteria-synergized multimodal cancer therapies are highlighted.

Evolving Tumor Characteristics and Smart Nanodrugs for Tumor Immunotherapy

Typical physiological characteristics of tumors, such as weak acidity, low oxygen content, and upregulation of certain enzymes in the tumor microenvironment (TME), provide survival advantages when exposed to targeted attacks by drugs and responsive nanomedicines. Consequently, cancer treatment has significantly progressed in recent years. However, the evolution and adaptation of tumor characteristics still pose many challenges for current treatment methods. Therefore, efficient and precise cancer treatments require an understanding of the heterogeneity degree of various factors in cancer cells during tumor evolution to exploit the typical TME characteristics and manage the mutation process. The highly heterogeneous tumor and infiltrating stromal cells, immune cells, and extracellular components collectively form a unique TME, which plays a crucial role in tumor malignancy, including proliferation, invasion, metastasis, and immune escape. Therefore, the development of new treatment methods that can adapt to the evolutionary characteristics of tumors has become an intense focus in current cancer treatment research. This paper explores the latest understanding of cancer evolution, focusing on how tumors use new antigens to shape their "new faces"; how immune system cells, such as cytotoxic T cells, regulatory T cells, macrophages, and natural killer cells, help tumors become "invisible", that is, immune escape; whether the diverse cancer-associated fibroblasts provide support and coordination for tumors; and whether it is possible to attack tumors in reverse. This paper discusses the limitations of targeted therapy driven by tumor evolution factors and explores future strategies and the potential of intelligent nanomedicines, including the systematic coordination of tumor evolution factors and adaptive methods, to meet this therapeutic challenge.

Nanoparticle/Engineered Bacteria Based Triple-Strategy Delivery System for Enhanced Hepatocellular Carcinoma Cancer Therapy

Background

New treatment modalities for hepatocellular carcinoma (HCC) are desperately critically needed, given the lack of specificity, severe side effects, and drug resistance with single chemotherapy. Engineered bacteria can target and accumulate in tumor tissues, induce an immune response, and act as drug delivery vehicles. However, conventional bacterial therapy has limitations, such as drug loading capacity and difficult cargo release, resulting in inadequate therapeutic outcomes. Synthetic biotechnology can enhance the precision and efficacy of bacteria-based delivery systems. This enables the selective release of therapeutic payloads in vivo.

Methods

In this study, we constructed a non-pathogenic Escherichia coli (E. coli) with a synchronized lysis circuit as both a drug/gene delivery vehicle and an in-situ (hepatitis B surface antigen) Ag (ASEc) producer. Polyethylene glycol (CHO-PEG2000-CHO)-poly(ethyleneimine) (PEI25k)-citraconic anhydride (CA)-doxorubicin (DOX) nanoparticles loaded with plasmid encoded human sulfatase 1 (hsulf-1) enzyme (PNPs) were anchored on the surface of ASEc (ASEc@PNPs). The composites were synthesized and characterized. The in vitro and in vivo anti-tumor effect of ASEc@PNPs was tested in HepG2 cell lines and a mouse subcutaneous tumor model.

Results

The results demonstrated that upon intravenous injection into tumor-bearing mice, ASEc can actively target and colonise tumor sites. The lytic genes to achieve blast and concentrated release of Ag significantly increased cytokine secretion and the intratumoral infiltration of CD4/CD8+T cells, initiated a specific immune response. Simultaneously, the PNPs system releases hsulf-1 and DOX into the tumor cell resulting in rapid tumor regression and metastasis prevention.

Conclusion

The novel drug delivery system significantly suppressed HCC in vivo with reduced side effects, indicating a potential strategy for clinical HCC therapy.

Tea polyphenol-engineered hybrid cellular nanovesicles for cancer immunotherapy and androgen deprivation therapy

Androgen deprivation therapy (ADT) is a crucial and effective strategy for prostate cancer, while systemic administration may cause profound side effects on normal tissues. More importantly, the ADT can easily lead to resistance by involving the activation of NF-κB signaling pathway and high infiltration of M2 macrophages in tumor microenvironment (TME). Herein, we developed a biomimetic nanotherapeutic platform by deriving cell membrane nanovesicles from cancer cells and probiotics to yield the hybrid cellular nanovesicles (hNVs), loading flutamide (Flu) into the resulting hNVs, and finally modifying the hNVs@Flu with Epigallocatechin-3-gallate (EGCG). In this nanotherapeutic platform, the hNVs significantly improved the accumulation of hNVs@Flu-EGCG in tumor sites and reprogramed immunosuppressive M2 macrophages into antitumorigenic M1 macrophages, the Flu acted on androgen receptors and inhibited tumor proliferation, and the EGCG promoted apoptosis of prostate cancer cells by inhibiting the NF-κB pathway, thus synergistically stimulating the antitumor immunity and reducing the side effects and resistance of ADT. In a prostate cancer mouse model, the hNVs@Flu-EGCG significantly extended the lifespan of mice with tumors and led to an 81.78% reduction in tumor growth compared with the untreated group. Overall, the hNVs@Flu-EGCG are safe, modifiable, and effective, thus offering a promising platform for effective therapeutics of prostate cancer.

Metabolic Regulation-Mediated Reversion of the Tumor Immunosuppressive Microenvironment for Potentiating Cooperative Metabolic Therapy and Immunotherapy

Tumor cells exhibit heightened glucose (Glu) consumption and increased lactic acid (LA) production, resulting in the formation of an immunosuppressive tumor microenvironment (TME) that facilitates malignant proliferation and metastasis. In this study, we meticulously engineer an antitumor nanoplatform, denoted as ZLGCR, by incorporating glucose oxidase, LA oxidase, and CpG oligodeoxynucleotide into zeolitic imidazolate framework-8 that is camouflaged with a red blood cell membrane. Significantly, ZLGCR-mediated consumption of Glu and LA not only amplifies the effectiveness of metabolic therapy but also reverses the immunosuppressive TME, thereby enhancing the therapeutic outcomes of CpG-mediated antitumor immunotherapy. It is particularly important that the synergistic effect of metabolic therapy and immunotherapy is further augmented when combined with immune checkpoint blockade therapy. Consequently, this engineered antitumor nanoplatform will achieve a cooperative tumor-suppressive outcome through the modulation of metabolism and immune responses within the TME.

Co-delivery of doxorubicin and STING agonist cGAMP for enhanced antitumor immunity

Many chemotherapeutic agents can induce immunogenic cell death (ICD), which leads to the release of danger-associated molecular patterns (DAMPs) and tumor-associated antigens. This process promotes dendritic cells (DCs) maturation and cytotoxic T lymphocyte (CTL) infiltration. However, cancer cells can employ diverse mechanisms to evade the host immune system. Recent studies have shown that stimulator of interferon genes (STING) agonists, such as cGAMP, can amplify ICD-triggered immune responses and enhance the infiltration of immune cells into the tumor microenvironment (TME). Building upon these findings, we constructed a doxorubicin (DOX) and cGAMP co-delivery system (DOX/cGAMP@NPs) for melanoma and triple-negative breast cancer (TNBC) therapy. The results demonstrated that DOX could effectively destroy tumors and induce the release of DAMPs by ICD. Furthermore, in orthotopic 4T1 tumors mice model and subcutaneous B16 tumor mice model, cGAMP could promote the maturation of DCs and CD8+ T cell activation and infiltration by inducing the secretion of type I interferons and pro-inflammation cytokine, which amplified the antitumor immune response induced by DOX. This strategy also promoted the depletion of immunosuppressive cells, potentially alleviating the immunosuppressive TME. In conclusion, our study highlights the combination of DOX-induced ICD and the immune-enhancing properties of cGAMP holds significant implications for future research and clinical applications.

The emerging tumor microbe microenvironment: From delineation to multidisciplinary approach-based interventions

Intratumoral microbiota has become research hotspots, and emerges as a non-negligent new component of tumor microenvironments (TME), due to its powerful influence on tumor initiation, metastasis, immunosurveillance and prognosis despite in low-biomass. The accumulations of microbes, and their related components and metabolites within tumor tissues, endow TME with additional pluralistic features which are distinct from the conventional one. Therefore, it's definitely necessary to comprehensively delineate the sophisticated landscapes of tumor microbe microenvironment, as well as their functions and related underlying mechanisms. Herein, in this review, we focused on the fields of tumor microbe microenvironment, including the heterogeneity of intratumor microbiota in different types of tumors, the controversial roles of intratumoral microbiota, the basic features of tumor microbe microenvironment (i.e., pathogen-associated molecular patterns (PAMPs), typical microbial metabolites, autophagy, inflammation, multi-faceted immunomodulation and chemoresistance), as well as the multidisciplinary approach-based intervention of tumor microbiome for cancer therapy by applying wild-type or engineered live microbes, microbiota metabolites, antibiotics, synthetic biology and rationally designed biomaterials. We hope our work will provide valuable insight to deeply understand the interplay of cancer-immune-microbial, and facilitate the development of microbes-based tumor-specific treatments.

Oral probiotics microgel plus Galunisertib reduced TGF-β blockade resistance and enhanced anti-tumor immune responses in colorectal cancer

Transforming growth factor β (TGF-β), a versatile immunosuppressive cytokine, has gained increasing attention as a potential target for cancer immunotherapy. However, current strategies are constrained by tumor heterogeneity and drug resistance. Therapeutic probiotics, such as Escherichia coli Nissle1917 (EcN), not only regulate the gut microbiota to increase beneficial bacteria with anti-tumor effects, but also modulate immune factors within the body, thereby enhancing immunity. In this study, we developed an oral microgel delivery system of EcN@(CS-SA)2 by electrostatic interaction between chitosan (CS) and sodium alginate (SA), aiming to enhance its bioavailability in the gastrointestinal tract (GIT). Notably, EcN@(CS-SA)2 microgel showed a synergistic enhancement of the anti-tumor efficacy of Galunisertib (Gal, a TGF-β inhibitor) by inducing apoptosis and immunogenic cell death (ICD) in tumor cells, as well as promoting increased infiltration of CD8+ T cells into the tumor microenvironment (TME).