Boarding Oncolytic Viruses onto Tumor-Homing Bacterium-Vessels for Augmented Cancer Immunotherapy

Sialidase-Chimeric Bioengineered Bacteria for Tumor-Sialoglycan-Triggered Solid Tumor Therapy

Adoptive cell therapies for solid tumors are usually limited by off-target antigens, incapable tissue infiltration, and cell function exhaustion. In contrast, bacterial cells possess the inherent competencies of preferential tumor targeting, deep tissue penetration, and high intratumoral bioactivity and represent promising alternatives to overcome these challenges. Here, a sialic-acid-responsive regulatory gene circuit is engineered into Escherichia coli MG1655 to express cytolysin of hemolysin E (HlyE). Furthermore, sialidases are bioorthogonally decorated onto the surface of azido-functionalized bioengineered bacteria for recognizing tumor sialoglycans and cleaving their sialosides into free sialic acids. As chemical inducers, sialic acids feedbackingly activate the bacterial gene circuit to produce HlyE and lyse tumor cells. This study mimics the tumor antigen-induced cytotoxin production and cell lysis that occurs in chimeric antigen receptor T (CAR-T) cells yet surmounts the intrinsic limitations of adoptive cell therapies. Moreover, sialidase-mediated tumor cell desialylation also reverses the immunosuppressive effect of glycoimmune checkpoints and further improves the therapeutic effect of solid tumors.

Microbe-material hybrids for therapeutic applications

As natural living substances, microorganisms have emerged as useful resources in medicine for creating microbe-material hybrids ranging from nano to macro dimensions. The engineering of microbe-involved nanomedicine capitalizes on the distinctive physiological attributes of microbes, particularly their intrinsic "living" properties such as hypoxia tendency and oxygen production capabilities. Exploiting these remarkable characteristics in combination with other functional materials or molecules enables synergistic enhancements that hold tremendous promise for improved drug delivery, site-specific therapy, and enhanced monitoring of treatment outcomes, presenting substantial opportunities for amplifying the efficacy of disease treatments. This comprehensive review outlines the microorganisms and microbial derivatives used in biomedicine and their specific advantages for therapeutic application. In addition, we delineate the fundamental strategies and mechanisms employed for constructing microbe-material hybrids. The diverse biomedical applications of the constructed microbe-material hybrids, encompassing bioimaging, anti-tumor, anti-bacteria, anti-inflammation and other diseases therapy are exhaustively illustrated. We also discuss the current challenges and prospects associated with the clinical translation of microbe-material hybrid platforms. Therefore, the unique versatility and potential exhibited by microbe-material hybrids position them as promising candidates for the development of next-generation nanomedicine and biomaterials with unique theranostic properties and functionalities.

Beyond the Gut: The intratumoral microbiome's influence on tumorigenesis and treatment response

The intratumoral microbiome (TM) refers to the microorganisms in the tumor tissues, including bacteria, fungi, viruses, and so on, and is distinct from the gut microbiome and circulating microbiota. TM is strongly associated with tumorigenesis, progression, metastasis, and response to therapy. This paper highlights the current status of TM. Tract sources, adjacent normal tissue, circulatory system, and concomitant tumor co-metastasis are the main origin of TM. The advanced techniques in TM analysis are comprehensively summarized. Besides, TM is involved in tumor progression through several mechanisms, including DNA damage, activation of oncogenic signaling pathways (phosphoinositide 3-kinase [PI3K], signal transducer and activator of transcription [STAT], WNT/β-catenin, and extracellular regulated protein kinases [ERK]), influence of cytokines and induce inflammatory responses, and interaction with the tumor microenvironment (anti-tumor immunity, pro-tumor immunity, and microbial-derived metabolites). Moreover, promising directions of TM in tumor therapy include immunotherapy, chemotherapy, radiotherapy, the application of probiotics/prebiotics/synbiotics, fecal microbiome transplantation, engineered microbiota, phage therapy, and oncolytic virus therapy. The inherent challenges of clinical application are also summarized. This review provides a comprehensive landscape for analyzing TM, especially the TM-related mechanisms and TM-based treatment in cancer.

Magnetically Induced Thermal Effects on Tobacco Mosaic Virus-Based Nanocomposites for a Programmed Disassembly of Protein Cages

Protein cages are promising tools for the controlled delivery of therapeutics and imaging agents when endowed with programmable disassembly strategies. Here, we produced hybrid nanocomposites made of tobacco mosaic virus (TMV) and magnetic iron oxide nanoparticles (IONPs), designed to disrupt the viral protein cages using magnetically induced release of heat. We studied the effects of this magnetic hyperthermia on the programmable viral protein capsid disassembly using (1) elongated nanocomposites of TMV coated heterogeneously with magnetic iron oxide nanoparticles (TMV@IONPs) and (2) spherical nanocomposites of polystyrene (PS) on which we deposited presynthesized IONPs and TMV via layer-by-layer self-assembly (PS@IONPs/TMV). Notably, we found that the extent of the disassembly of the protein cages is contingent upon the specific absorption rate (SAR) of the magnetic nanoparticles, that is, the heating efficiency, and the relative position of the protein cage within the nanocomposite concerning the heating sources. This implies that the spatial arrangement of components within the hybrid nanostructure has a significant impact on the disassembly process. Understanding and optimizing this relationship will contribute to the critical spatiotemporal control for targeted drug and gene delivery using protein cages.

Cancer therapy with the viral and bacterial pathogens: The past enemies can be considered the present allies

Cancer continues to be one of the leading causes of mortality worldwide despite significant advancements in cancer treatment. Many difficulties have arisen as a result of the detrimental consequences of chemotherapy and radiotherapy as a common cancer therapy, such as drug inability to penetrate deep tumor tissue, and also the drug resistance in tumor cells continues to be a major concern. These obstacles have increased the need for the development of new techniques that are more selective and effective against cancer cells. Bacterial-based therapies and the use of oncolytic viruses can suppress cancer in comparison to other cancer medications. The tumor microenvironment is susceptible to bacterial accumulation and proliferation, which can trigger immune responses against the tumor. Oncolytic viruses (OVs) have also gained considerable attention in recent years because of their potential capability to selectively target and induce apoptosis in cancer cells. This review aims to provide a comprehensive summary of the latest literature on the role of bacteria and viruses in cancer treatment, discusses the limitations and challenges, outlines various strategies, summarizes recent preclinical and clinical trials, and emphasizes the importance of optimizing current strategies for better clinical outcomes.

Tuning cellular metabolism for cancer virotherapy

Oncolytic viruses (OVs) represent an emerging immunotherapeutic strategy owing to their capacity for direct tumor lysis and induction of antitumor immunity. However, hurdles like transient persistence and moderate efficacy necessitate innovative approaches. Metabolic remodeling has recently gained prominence as a strategic intervention, wherein OVs or combination regimens could reprogram tumor and immune cell metabolism to enhance viral replication and oncolysis. In this review, we summarize recent advances in strategic reprogramming of tumor and immune cell metabolism to enhance OV-based immunotherapies. Specific tactics include engineering viruses to target glycolytic, glutaminolytic, and nucleotide synthesis pathways in cancer cells, boosting viral replication and tumor cell death. Additionally, rewiring T cell and NK cell metabolism of lipids, amino acids, and carbohydrates shows promise to enhance antitumor effects. Further insights are discussed to pave the way for the clinical implementation of metabolically enhanced oncolytic platforms, including balancing metabolic modulation to limit antiviral responses while promoting viral persistence and tumor clearance.

Bio-inspired drug delivery systems: A new attempt from bioinspiration to biomedical applications

Natural organisms have evolved sophisticated and multiscale hierarchical structures over time to enable survival. Currently, bionic design is revolutionizing drug delivery systems (DDS), drawing inspiration from the structure and properties of natural organisms that offer new possibilities to overcome the challenges of traditional drug delivery systems. Bionic drug delivery has contributed to a significant improvement in therapeutic outcomes, providing personalized regimens for patients with various diseases and enhancing both their quality of life and drug efficacy. Therefore, it is important to summarize the progress made so far and to discuss the challenges and opportunities for future development. Herein, we review the recent advances in bio-inspired materials, bio-inspired drug vehicles, and drug-loading platforms of biomimetic structures and properties, emphasizing the importance of adapting the structure and function of organisms to meet the needs of drug delivery systems. Finally, we highlight the delivery strategies of bionics in DDS to provide new perspectives and insights into the research and exploration of bionics in DDS. Hopefully, this review will provide future insights into utilizing biologically active vehicles, bio-structures, and bio-functions, leading to better clinical outcomes.

Role and significance of virus-bacteria interactions in disease progression

Understanding disease pathogenesis caused by bacteria/virus, from the perspective of individual pathogen has provided meaningful insights. However, as viral and bacterial counterparts might inhabit the same infection site, it becomes crucial to consider their interactions and contributions in disease onset and progression. The objective of the review is to highlight the importance of considering both viral and bacterial agents during the course of coinfection. The review provides a unique perspective on the general theme of virus-bacteria interactions, which either lead to colocalized infections that are restricted to one anatomical niche, or systemic infections that have a systemic effect on the human host. The sequence, nature, and underlying mechanisms of certain virus-bacteria interactions have been elaborated with relevant examples from literature. It also attempts to address the various applied aspects, including diagnostic and therapeutic strategies for individual infections as well as virus-bacteria coinfections. The review aims to aid researchers in comprehending the intricate interplay between virus and bacteria in disease progression, thereby enhancing understanding of current methodologies and empowering the development of novel health care strategies to tackle coinfections.

Boarding pyroptosis onto nanotechnology for cancer therapy

Pyroptosis, a non-apoptotic programmed cellular inflammatory death mechanism characterized by gasdermin (GSDM) family proteins, has gathered significant attention in the cancer treatment. However, the alarming clinical trial data indicates that pyroptosis-mediated cancer therapeutic efficiency is still unsatisfactory. It is essential to integrate the burgeoning biomedical findings and innovations with potent technology to hasten the development of pyroptosis-based antitumor drugs. Considering the rapid development of pyroptosis-driven cancer nanotherapeutics, here we aim to summarize the recent advances in this field at the intersection of pyroptosis and nanotechnology. First, the foundation of pyroptosis-based nanomedicines (NMs) is outlined to illustrate the reliability and effectiveness for the treatment of tumor. Next, the emerging nanotherapeutics designed to induce pyroptosis are overviewed. Moreover, the cross-talk between pyroptosis and other cell death modalities are discussed, aiming to explore the mechanistic level relationships to provide guidance strategies for the combination of different types of antitumor drugs. Last but not least, the opportunities and challenges of employing pyroptosis-based NMs in potential clinical cancer therapy are highlighted.

Enhancing oncolytic virus efficiency with methionine and N-(3-aminoprolil)methacrylamide modified acrylamide cationic block polymer

Oncolytic virus ablation of tumor cells has the advantages of high tumor selectivity, strong immunogenicity, and low side effects. However, the recognition and clearance of oncolytic viruses by the immune system are the main factors limiting their anti-tumor efficiency. As a highly biosafe and highly modifiable oncolytic virus vector, acrylamide can improve the long-term circulation of oncolytic viruses. Still, it is limited in its uptake efficiency by tumor cells. Herein, we constructed an N-hydroxymethyl acrylamide-b-(N-3-aminopropyl methacrylamide)-b-DMC block copolymer (NMA-b-APMA-b-DMA, NAD) as an oncolytic virus carrier, which not only improves the long-term circulation of oncolytic viruses in the body but also shows excellent stability for loading an oncolytic virus. The data shows that there was no obvious difference in the transfection effect of the NAD/Ad complex with or without neutralizing antibodies in the medium, which meant that the cationic carrier mediated by NAD/Ad had good serum stability. Only 10 micrograms of NAD carrier are needed to load the oncolytic virus, which can increase the transfection efficiency by 50 times. Cell experiments and mouse animal experiments show that NAD vectors can significantly enhance the anti-tumor effect of oncolytic viruses. We hope that this work will promote the application of acrylamide as an oncolytic virus vector and provide new ideas for methods to modify acrylamide for biomedical applications.

Tumor-targeted delivery of copper-manganese biomineralized oncolytic adenovirus for colorectal cancer immunotherapy

Oncolytic viral therapy (OVT) is a novel anti-tumor immunotherapy approach, specifically replicating within tumor cells. Currently, oncolytic viruses are mainly administered by intratumoral injection. However, achieving good results for distant metastatic tumors is challenging. In this study, a multifunctional oncolytic adenovirus, OA@CuMnCs, was developed using bimetallic ions copper and manganese. These metal cations form a biomineralized coating on the virus's surface, reducing immune clearance. It is known that viruses upregulate the expression of PD-L1. Copper ions in OA@CuMnCs can decrease the PD-L1 expression of tumor cells, thereby promoting immune cell-related factor release. This process involves antigen presentation and the combination of immature dendritic cells, transforming them into mature dendritic cells. It changes "cold" tumors into "hot" tumors, further inducing immunogenic cell death. While oncolytic virus replication requires oxygen, manganese ions in OA@CuMnCs can react with endogenous hydrogen peroxide. This reaction produces oxygen, enhancing the virus's replication ability and the tumor lysis effect. Thus, this multifunctionally coated OA@CuMnCs demonstrates potent amplification in immunotherapy efficacy, and shows great potential for further clinical OVT. STATEMENT OF SIGNIFICANCE: Oncolytic virus therapy (OVs) is a new anti-tumor immunotherapy method that can specifically replicate in tumor cells. Although the oncolytic virus can achieve a therapeutic effect on some non-metastatic tumors through direct intratumoral injection, there are still three major defects in the treatment of metastatic tumors: immune response, hypoxia effect, and administration route. Various studies have shown that the immune response in vivo can be overcome by modifying or wrapping the surface protein of the oncolytic virus. In this paper, a multifunctional coating of copper and manganese was prepared by combining the advantages of copper and manganese ions. The coating has a simple preparation method and mild conditions, and can effectively enhance tumor immunotherapy.

Liposome-based nanomedicine for immune checkpoint blocking therapy and combinatory cancer therapy

The discovery of immune checkpoint (IC) has led to a wave of leap forward in cancer immunotherapy that represents probably the most promising strategy for cancer therapy. However, the clinical use of immune checkpoint block (ICB) therapy is limited by response rates and side effects. A strategy that addresses the limitations of ICB therapies through combination therapies, using nanocarriers as mediators, has been mentioned in numerous research papers. Liposomes have been probably one of the most extensively used nanocarriers for clinical applications, with broad drug delivery and high safety. A timely review on this hot subject of research, i.e., the application of liposomes for ICB, is thus highly desirable for both fundamental and clinical translatable studies, but remains, to our knowledge, unexplored so far. For this purpose, this review is composed to address the dilemma of ICB therapy and the reasons for this dilemma. We later describe how other cancer treatments have broken this dilemma. Finally, we focus on the role of liposomes in various combinatory cancer therapy. This review is believed to serve as a guidance for the rational design and development of liposome for immunotherapy with enhanced therapeutic efficiency.

Micro-to-Nano Oncolytic Microbial System Shifts from Tumor Killing to Tumor Draining Lymph Nodes Remolding for Enhanced Immunotherapy

Because the tumor-draining lymph nodes (TDLNs) microenvironment is commonly immunosuppressive, oncolytic microbe-induced tumor antigens aren't sufficiently cross-primed tumor specific T cells through antigen-presenting cells (e.g., dendritic cells (DCs)) in TDLNs. Herein, this work develops the micro-to-nano oncolytic microbial therapeutics based on pyranose oxidase (P2 O) overexpressed Escherichia coli (EcP) which are simultaneously encapsulated by PEGylated mannose and low-concentrated photosensitizer nanoparticles (NPs). Following administration, P2 O from this system generates toxic hydrogen peroxide for tumor regression and leads to the release of tumor antigens. The "microscale" EcP is triggered, following exposure to the laser irradiation, to secrete the "nanoscale" bacterial outer membrane vesicles (OMVs). The enhanced TDLNs delivery via OMVs significantly regulates the TDLNs immunomicroenvironment, promoting the maturation of DCs to potentiate tumor antigen-specific T cells immune response. The micro-to-nano oncolytic microbe is leveraged to exert tumor killing and remold TDLNs for initiating potent activation of DCs, providing promising strategies to facilitate microbial cancer vaccination.

The role of intestinal flora on tumor immunotherapy: recent progress and treatment implications

Immunotherapy, specifically immune checkpoint inhibitors, has emerged as a promising approach for treating malignant tumors. The gut, housing approximately 70 % of the body's immune cells, is abundantly populated with gut bacteria that actively interact with the host's immune system. Different bacterial species within the intestinal flora are in a delicate equilibrium and mutually regulate each other. However, when this balance is disrupted, pathogenic microorganisms can dominate, adversely affecting the host's metabolism and immunity, ultimately promoting the development of disease. Emerging researches highlight the potential of interventions such as fecal microflora transplantation (FMT) to improve antitumor immune response and reduce the toxicity of immunotherapy. These remarkable findings suggest the major role of intestinal flora in the development of cancer immunotherapy and led us to the hypothesis that intestinal flora transplantation may be a new breakthrough in modifying immunotherapy side effects.

NK cell-based tumor immunotherapy

Natural killer (NK) cells display a unique inherent ability to identify and eliminate virus-infected cells and tumor cells. They are particularly powerful for elimination of hematological cancers, and have attracted considerable interests for therapy of solid tumors. However, the treatment of solid tumors with NK cells are less effective, which can be attributed to the very complicated immunosuppressive microenvironment that may lead to the inactivation, insufficient expansion, short life, and the poor tumor infiltration of NK cells. Fortunately, the development of advanced nanotechnology has provided potential solutions to these issues, and could improve the immunotherapy efficacy of NK cells. In this review, we summarize the activation and inhibition mechanisms of NK cells in solid tumors, and the recent advances in NK cell-based tumor immunotherapy boosted by diverse nanomaterials. We also propose the challenges and opportunities for the clinical application of NK cell-based tumor immunotherapy.

Living virus-based nanohybrids for biomedical applications

Living viruses characterized by distinctive biological functions including specific targeting, gene invasion, immune modulation, and so forth have been receiving intensive attention from researchers worldwide owing to their promising potential for producing numerous theranostic modalities against diverse pathological conditions. Nevertheless, concerns during applications, such as rapid immune clearance, altering immune activation modes, insufficient gene transduction efficiency, and so forth, highlight the crucial issues of excessive therapeutic doses and the associated biosafety risks. To address these concerns, synthetic nanomaterials featuring unique physical/chemical properties are frequently exploited as efficient drug delivery vehicles or treatments in biomedical domains. By constant endeavor, researchers nowadays can create adaptable living virus-based nanohybrids (LVN) that not only overcome the limitations of virotherapy, but also combine the benefits of natural substances and nanotechnology to produce novel and promising therapeutic and diagnostic agents. In this review, we discuss the fundamental physiochemical properties of the viruses, and briefly outline the basic construction methodologies of LVN. We then emphasize their distinct diagnostic and therapeutic performances for various diseases. Furthermore, we survey the foreseeable challenges and future perspectives in this interdisciplinary area to offer insights. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Advances and challenges in the treatment of lung cancer

Lung cancer accounts for a relatively high proportion of malignant tumors. As the most prevalent type of lung cancer, non-small cell lung cancer (NSCLC) is characterized by high morbidity and mortality. Presently, the arsenal of treatment strategies encompasses surgical resection, chemotherapy, targeted therapy and radiotherapy. However, despite these options, the prognosis remains distressingly poor with a low 5-year survival rate. Therefore, it is urgent to pursue a paradigm shift in treatment methodologies. In recent years, the advent of sophisticated biotechnologies and interdisciplinary integration has provided innovative approaches for the treatment of lung cancer. This article reviews the cutting-edge developments in the nano drug delivery system, molecular targeted treatment system, photothermal treatment strategy, and immunotherapy for lung cancer. Overall, by systematically summarizing and critically analyzing the latest progress and current challenges in these treatment strategies of lung cancer, we aim to provide a theoretical basis for the development of novel drugs for lung cancer treatment, and thus improve the therapeutic outcomes for lung cancer patients.

Advanced Generation Therapeutics: Biomimetic Nanodelivery System for Tumor Immunotherapy

Tumor immunotherapy is a safe and effective strategy for precision medicine. However, immunotherapy for most cancer cases still ends in failure, with the root causes of the immunosuppressive and extraordinary heterogeneity of the solid tumors microenvironment. The emerging biomimetic nanodelivery system provides a promising tactic to improve the immunotherapy effect while reducing the adverse reactions on nontarget cells. Herein, we summarize the relationship between tumor occurrence and tumor immune microenvironment, mechanism of tumor immune escape, immunotherapy classification (including adoptive cellular therapy, cytokines, cancer vaccines, and immune checkpoint inhibitors) and recommend target cells for immunotherapy first, and then emphatically introduce the recent advances and applications of the latest biomimetic nanodelivery systems (e.g., immune cells, erythrocytes, tumor cells, platelets, bacteria) in tumor immunotherapy. Meanwhile, we separately summarize the application of tumor vaccines. Finally, the predictable challenges and perspectives in a forward exploration of biomimetic nanodelivery systems for tumor immunotherapy are also discussed.

Oncolytic adenoviruses expressing checkpoint inhibitors for cancer therapy

Despite the remarkable success of immune checkpoint inhibitors (ICIs), primary resistance to ICIs causes only subsets of patients to achieve durable responses due to the complex tumor microenvironment (TME). Oncolytic viruses (OVs) can overcome the immunosuppressive TME and promote systemic antitumor immunity in hosts. Engineered OVs armed with ICIs would likely have improved effectiveness as a cancer therapy. According to the diverse immune cell landscapes among different types of tumors, we rationally and precisely generated three recombinant oncolytic adenoviruses (OAds): OAd-SIRPα-Fc, OAd-Siglec10-Fc and OAd-TIGIT-Fc. These viruses were designed to locally deliver SIRPα-Fc, Siglec10-Fc or TIGIT-Fc fusion proteins recognizing CD47, CD24 or CD155, respectively, in the TME to achieve enhanced antitumor effects. Our results suggested that OAd-SIRPα-Fc and OAd-Siglec10-Fc both showed outstanding efficacy in tumor suppression of macrophage-dominated tumors, while OAd-TIGIT-Fc showed the best antitumor immunity in CD8+ T-cell-dominated tumors. Importantly, the recombinant OAds activated an inflammatory immune response and generated long-term antitumor memory. In addition, the combination of OAd-Siglec10-Fc with anti-PD-1 significantly enhanced the antitumor effect in a 4T1 tumor model by remodeling the TME. In summary, rationally designed OAds expressing ICIs tailored to the immune cell landscape in the TME can precisely achieve tumor-specific immunotherapy of cancer.

A Bionic Yeast Tumor Vaccine Using the Co-Loading Strategy to Prevent Post-Operative Tumor Recurrence

Immunotherapy is an effective adjunct to surgery for preventing tumor recurrence and metastasis in postoperative tumor patients. Although mimicking microbial invasion and immune activation pathways can effectively stimulate the immune system, the limited capacity of microbial components to bind antigens and adjuvants restricts the development of this system. Here, we construct bionic yeast carriers (BYCs) by in situ polymerization of mesoporous silica nanoparticles (MSNs) within the yeast capsules (YCs). BYCs can mimic the yeast infection pathway while utilizing the loading capacity of MSNs for multiple substances. Pore size and hydrophobicity-modified BYC can be loaded with both antigen and adjuvant R848. Oral or subcutaneous injection uptake of coloaded BYCs demonstrated positive therapeutic effects as a tumor therapeutic vaccine in both the transplantation tumor model and the metastasis tumor model. 57% of initial 400 mm3 tumor recurrence models are completely cured with coloaded BYCs via combination therapy with surgery, utilizing surgically resected tumors as antigens. The BYCs construction and coloading strategy will provide insights and optimistic approaches for the development of effective and controllable cancer vaccine carriers.

Bacteria and Bacterial Components as Natural Bio-Nanocarriers for Drug and Gene Delivery Systems in Cancer Therapy

Bacteria and bacterial components possess multifunctional properties, making them attractive natural bio-nanocarriers for cancer diagnosis and targeted treatment. The inherent tropic and motile nature of bacteria allows them to grow and colonize in hypoxic tumor microenvironments more readily than conventional therapeutic agents and other nanomedicines. However, concerns over biosafety, limited antitumor efficiency, and unclear tumor-targeting mechanisms have restricted the clinical translation and application of natural bio-nanocarriers based on bacteria and bacterial components. Fortunately, bacterial therapies combined with engineering strategies and nanotechnology may be able to reverse a number of challenges for bacterial/bacterial component-based cancer biotherapies. Meanwhile, the combined strategies tend to enhance the versatility of bionanoplasmic nanoplatforms to improve biosafety and inhibit tumorigenesis and metastasis. This review summarizes the advantages and challenges of bacteria and bacterial components in cancer therapy, outlines combinatorial strategies for nanocarriers and bacterial/bacterial components, and discusses their clinical applications.

Advances in anti-tumor based on various anaerobic bacteria and their derivatives as drug vehicles

Cancer therapies, such as chemotherapy and radiotherapy, are often unsatisfactory due to several limitations, including drug resistance, inability to cross biological barriers, and toxic side effects on the body. These drawbacks underscore the need for alternative treatments that can overcome these challenges and provide more effective and safer options for cancer patients. In recent years, the use of live bacteria, engineered bacteria, or bacterial derivatives to deliver antitumor drugs to specific tumor sites for controlled release has emerged as a promising therapeutic tool. This approach offers several advantages over traditional cancer therapies, including targeted drug delivery and reduced toxicity to healthy tissues. Ongoing research in this field holds great potential for further developing more efficient and personalized cancer therapies, such as E. coli, Salmonella, Listeria, and bacterial derivatives like outer membrane vesicles (OMVs), which can serve as vehicles for drugs, therapeutic proteins, or antigens. In this review, we describe the advances, challenges, and future directions of research on using live bacteria or OMVs as carriers or components derived from bacteria of delivery systems for cancer therapy.

Immunotherapy: cancer immunotherapy and its combination with nanomaterials and other therapies

Immunotherapy is a new type of tumor treatment after surgery, radiotherapy and chemotherapy, and can be used to manage and destroy tumor cells through activating or strengthening the immune response. Immunotherapy has the benefits of a low recurrence rate and high specificity compared to traditional treatment methods. Immunotherapy has developed rapidly in recent years and has become a research hotspot. Currently, chimeric antigen receptor T-cell immunotherapy and immune checkpoint inhibitors are the most effective tumor immunotherapies in clinical practice. While tumor immunotherapy brings hope to patients, it also faces some challenges and still requires continuous research and progress. Combination therapy is the future direction of anti-tumor treatment. In this review, the main focus is on an overview of the research progress of immune checkpoint inhibitors, cellular therapies, tumor vaccines, small molecule inhibitors and oncolytic virotherapy in tumor treatment, as well as the combination of immunotherapy with other treatments.

Virus-Protein Corona Replacement Strategy to Improve the Antitumor Efficacy of Intravenously Injected Oncolytic Adenovirus

Intravenous administration of oncolytic adenoviruses (OVs) is a hopeful tumor therapeutic modality. However, the sharp clearance of OVs by the immune system dampens its effectiveness. Many studies have attempted to extend the circulation of intravenously administered OVs, almost all by preventing OVs from binding to neutralizing antibodies and complements in the blood, but the results have not been satisfactory. In contrast to previous conclusions, we found that the key to improving the circulation of OVs is to prevent the formation of the virus-protein corona rather than simply preventing the binding of neutralizing antibodies or complements to OVs. After identifying the key protein components of the virus-protein corona, we proposed a virus-protein corona replacement strategy, where an artificial virus-protein corona was formed on OVs to completely prevent the interaction of OVs with key virus-protein corona components in the plasma. It was found that this strategy dramatically prolonged the circulation time of OVs by over 30 fold and increased the distribution of OVs in tumors by over 10-fold, resulting in superior antitumor efficacy in primary and metastatic tumor models. Our finding provides a perspective on intravenous delivery of OVs, shifting the focus of future studies from preventing OV binding with neutralization antibodies and complements to preventing OVs from interacting with key virus-protein corona components in the plasma.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

A "bulldozer" driven by anoxic bacteria for pancreatic cancer chemo-immunotherapy

Immune evasion is a major obstacle for pancreatic ductal adenocarcinoma (PDAC) therapy. Inhibition of autophagy can improve antigen presentation and enlarge immunogenic cell death (ICD) effect to generate a strong anti-tumor immune response. However, abundant extracellular matrix dominated by hyaluronic acid (HA) hinders the deep penetration of autophagy inhibitors and ICD inducers. Herein, an intelligent autophagy inhibitor hydroxychloroquine (HCQ) and chemotherapeutic drug doxorubicin (DOX) co-loaded "bulldozer" (HD@HH/EcN) driven by anoxic bacteria was constructed for PDAC chemo-immunotherapy. Results demonstrated that probiotic Escherichia coli 1917 (EcN) could carry hyaluronidases (HAases)-hybrided albumin nanoparticles (HD@HH) to reach PDAC tumor tissue quickly and accurately. Thereafter, HAases can efficiently cleave the tumor matrix barrier and promote HD@HH/EcN to accumulate at tumor hypoxic core significantly. After that, high level of glutathione (GSH) in tumor microenvironment (TME) induces intermolecular disulfide bond in HD@HH nanoparticles breakage, to precisely release HCQ and DOX. DOX can induce ICD effect. Meanwhile, HCQ can amplify DOX induced ICD effect by inhibiting tumor autophagy, which further increase cell surface expression of major histocompatibility complex class I (MHC-I) and augment recruitment of CD8+ T cell to improve immunosuppressive TME. This study provides a new strategy for PDAC chemo-immunotherapy.

Oncolytic Virus-Driven Biotherapies from Bench to Bedside

With advances in cancer biology and an ever-deepening understanding of molecular virology, oncolytic virus (OV)-driven therapies have developed rapidly and become a promising alternative to traditional cancer therapies. In recent years, satisfactory results for oncolytic virus therapy (OVT) are achieved at both the cellular and organismal levels, and efforts are being increasingly directed toward clinical trials. Unfortunately, OVT remains ineffective in these trials, especially when performed using only a single OV reagent. In contrast, integrated approaches, such as using immunotherapy, chemotherapy, or radiotherapy, alongside OVT have demonstrated considerable efficacy. The challenges of OVT in clinical efficacy include the restricted scope of intratumoral injections and poor targeting of intravenous administration. Further optimization of OVT delivery is needed before OVs become a viable therapy for tumor treatment. In this review, the development process and antitumor mechanisms of OVs are introduced. The advances in OVT delivery routes to provide perspectives and directions for the improvement of OVT delivery are highlighted. This review also discusses the advantages and limitations of OVT monotherapy and combination therapy through the lens of recent clinical trials and aims to chart a course toward safer and more effective OVT strategies.

Engineered bacterial outer membrane vesicles encapsulating oncolytic adenoviruses enhance the efficacy of cancer virotherapy by augmenting tumor cell autophagy

Oncolytic adenovirus (Ad) infection promotes intracellular autophagy in tumors. This could kill cancer cells and contribute to Ads-mediated anticancer immunity. However, the low intratumoral content of intravenously delivered Ads could be insufficient to efficiently activate tumor over-autophagy. Herein, we report bacterial outer membrane vesicles (OMVs)-encapsulating Ads as microbial nanocomposites that are engineered for autophagy-cascade-augmented immunotherapy. Biomineral shells cover the surface antigens of OMVs to slow their clearance during in vivo circulation, enhancing intratumoral accumulation. After entering tumor cells, there is excessive H₂O₂ accumulation through the catalytic effect of overexpressed pyranose oxidase (P₂O) from microbial nanocomposite. This increases oxidative stress levels and triggers tumor autophagy. The autophagy-induced autophagosomes further promote Ads replication in infected tumor cells, leading to Ads-overactivated autophagy. Moreover, OMVs are powerful immunostimulants for remolding the immunosuppressive tumor microenvironment, facilitating antitumor immune response in preclinical cancer models in female mice. Therefore, the present autophagy-cascade-boosted immunotherapeutic method can expand OVs-based immunotherapy.

Multifunctional Nano-Biomaterials for Cancer Therapy via Inducing Enhanced Immunogenic Cell Death

Immunotherapy is considered to be one of the most promising methods to overcome cancer. Immunogenic cell death (ICD), as a special form of cell death that can trigger an antitumor immune response, has attracted increasing attention for cancer immunotherapy. Presently, ICD-mediating immunotherapy needs to overcome many hurdles including a lack of targeted delivery systems for ICD inducers, insufficient antitumor immunity, and the immunosuppressive tumor microenvironment. Recent research has demonstrated that nano-biomaterials exhibit unique biochemphysical properties at the nanoscale, providing a prospective approach to overcoming these obstacles. In this review, the authors first survey the occurrence, processes, and detection methods of ICD. Subsequently, the recent advances of nano-biomaterials applied to enhance ICD according to the key steps in the process of ICD, particularly with a focus on the mechanisms and lifting schemes are investigated. Finally, based on the achievement in the representative studies, the prospects and challenges of nanotechnology in ICD for cancer therapy are discussed to enable clinical translation.

Bacterial-Mediated Tumor Therapy: Old Treatment in a New Context

Targeted therapy and immunotherapy have brought hopes for precision cancer treatment. However, complex physiological barriers and tumor immunosuppression result in poor efficacy, side effects, and resistance to antitumor therapies. Bacteria-mediated antitumor therapy provides new options to address these challenges. Thanks to their special characteristics, bacteria have excellent ability to destroy tumor cells from the inside and induce innate and adaptive antitumor immune responses. Furthermore, bacterial components, including bacterial vesicles, spores, toxins, metabolites, and other active substances, similarly inherit their unique targeting properties and antitumor capabilities. Bacteria and their accessory products can even be reprogrammed to produce and deliver antitumor agents according to clinical needs. This review first discusses the role of different bacteria in the development of tumorigenesis and the latest advances in bacteria-based delivery platforms and the existing obstacles for application. Moreover, the prospect and challenges of clinical transformation of engineered bacteria are also summarized.

Engineered bacteria for augmented in situ tumor vaccination

In situ tumor vaccination has aroused tremendous interest with its capability for eliciting strong and systemic antitumor immune responses. Unlike traditional cancer vaccines, in situ tumor vaccination avoids the laborious process of tumor antigen identification and can modulate tumor immunosuppressive microenvironment at the same time. In recent years, bacteria have been used as both efficient tumor-targeted delivery vehicles and potent adjuvants. Regarding the rapid development in this area, in this review, we summarize recent advances in the application of bacteria for in situ cancer vaccination. We illustrate the mechanisms of bacteria as both efficient tumor immunogenic cell death inducers and tumor-targeted delivery platforms. Then we comprehensively review the engineering strategies for designing bacteria-based in situ vaccination, including chemical modification, nanotechnology, and genetic engineering. The current dilemma and future directions are discussed at the end of this review.

Oncolytic virus-based hepatocellular carcinoma treatment: Current status, intravenous delivery strategies, and emerging combination therapeutic solutions

Current treatments for advanced hepatocellular carcinoma (HCC) have limited success in improving patients' quality of life and prolonging life expectancy. The clinical need for more efficient and safe therapies has contributed to the exploration of emerging strategies. Recently, there has been increased interest in oncolytic viruses (OVs) as a therapeutic modality for HCC. OVs undergo selective replication in cancerous tissues and kill tumor cells. Strikingly, pexastimogene devacirepvec (Pexa-Vec) was granted an orphan drug status in HCC by the U.S. Food and Drug Administration (FDA) in 2013. Meanwhile, dozens of OVs are being tested in HCC-directed clinical and preclinical trials. In this review, the pathogenesis and current therapies of HCC are outlined. Next, we summarize multiple OVs as single therapeutic agents for the treatment of HCC, which have demonstrated certain efficacy and low toxicity. Emerging carrier cell-, bioengineered cell mimetic- or nonbiological vehicle-mediated OV intravenous delivery systems in HCC therapy are described. In addition, we highlight the combination treatments between oncolytic virotherapy and other modalities. Finally, the clinical challenges and prospects of OV-based biotherapy are discussed, with the aim of continuing to develop a fascinating approach in HCC patients.

A self-guidance biological hybrid drug delivery system driven by anaerobes to inhibit the proliferation and metastasis of colon cancer

Colorectal cancer is often accompanied by multiple organ metastasis. Anaerobic Bifidobacterium Infantis (BI) bacterial can selectively grow in hypoxic colorectal tumor microenvironment (TME), to own the natural advantage of preferentially colorectal tumor targeting. Herein, a self-guidance biological hybrid drug delivery system (BI-ES-FeAlg/DOX) based on BI was constructed to inhibit the proliferation and metastasis of colon cancer. Results demonstrated that BI-ES-FeAlg/DOX could overcome physical barriers to target and accumulate in colon tumor tissues. Then DOX was released to kill tumor cells along with the phase transition (solid to liquid) of FeAlg hydrogel, due to Fe³⁺ was reduced to Fe²⁺by intracellular GSH. Meanwhile, BI-ES selectively colonized into tumors and expressed endostatin (ES) protein to down-regulate VEGF and bFGF expression, exerting anti-angiogenic effect. Moreover, FeAlg catalyzed H₂O₂ in the local tumor to generate cytotoxic ·OH, further enhancing the antitumor effect. The pharmacodynamic result in AOM/DSS model proved that BI-ES-FeAlg/DOX had the best therapeutic effect, with the final V/V₀ of 2.19 ± 0.57, which was significantly lower than the other groups. Meanwhile, on CT-26 tumor-bearing model, it also showed an outstanding anti-tumor effect with inhibition rate of 82.12% ± 3.08%. In addition, lung metastases decreased significantly in tumor metastasis model after BI-ES-FeAlg/DOX treatment.

Photodynamic therapy-improved oncolytic bacterial immunotherapy with FAP-encoding S. typhimurium

Genetically engineered bacterial cancer therapy presents several advantages over conventional therapies. However, the anticancer effects of bacterium-based therapies remain insufficient, and serious side effects may be incurred with the increase in therapeutic dosages. Photodynamic therapy (PDT) suppresses tumor growth by producing reactive oxygen species (ROS) through specific laser-activated photosensitizers (PSs). Tumor-specific PS delivery and activatable ROS generation are two critical aspects for PDT advancement. Here, we propose PDT-enhanced oncolytic bacterial immunotherapy (OBI) by using genetically engineered avirulent Salmonella expressing a fluorogen-activating protein (FAP). Upon binding to a fluorogen, FAP could be activated and generate fluorescence and ROS. The instant activation of persistent fluorescence was detected in tumors through bacterium-based imaging. In a colon cancer model, PDT-OBI showed an enhanced tumor inhibition effect and prolonged animal survival. Mechanically, PDT generated ROS, resulting in the killing of cancer cells and over-accumulated bacteria. The pathogen-associated molecular patterns and damage-associated molecular patterns released from the destroyed bacteria and cancer cells recruited and activated immune cells (macrophages, neutrophils, and dendritic cells), which released additional proinflammatory cytokines (TNF-α and IL-1β); reduced anti-inflammatory cytokines (IL-10); and further enhanced immune cell infiltration in a positive-feedback manner, thus reducing bacterium-induced side effects and improving anticancer activities. This synergistic therapy has promising potential for cancer immunotherapy.

Strategies for Advanced Oncolytic Virotherapy: Current Technology Innovations and Clinical Approaches

Oncolytic virotherapy is a type of nanomedicine with a dual antitumor mechanism. Viruses are engineered to selectively infect and lyse cancer cells directly, leading to the release of soluble antigens which induce systemic antitumor immunity. Representative drug Talimogene laherparepvec has showed promising therapeutic effects in advanced melanoma, especially when combined with immune checkpoint inhibitors with moderate adverse effects. Diverse viruses like herpes simplex virus, adenovirus, vaccina virus, and so on could be engineered as vectors to express different transgenic payloads, vastly expanding the therapeutic potential of oncolytic virotherapy. A number of related clinical trials are under way which are mainly focusing on solid tumors. Studies about further optimizing the genome of oncolytic viruses or improving the delivering system are in the hotspot, indicating the future development of oncolytic virotherapy in the clinic. This review introduces the latest progress in clinical trials and pre-clinical studies as well as technology innovations directed at oncolytic viruses. The challenges and perspectives of oncolytic virotherapy towards clinical application are also discussed.