Biosynthetic neoantigen displayed on bacteria derived vesicles elicit systemic antitumour immunity

Self-luminous nanoengineered bacteria with the sustained release of interleukin 2 as an in situ vaccine for enhanced cancer immunotherapy

Bacteria-based in situ vaccination (ISV) has emerged as an effective therapeutic approach by activating anti-tumor immunity. However, inducing immunogenic cell death (ICD) and promoting effector T cell activation remain critical challenges in clinical applications of bacteria-based ISV. Here, we have developed a tumor microenvironment-activated nano-hybrid engineered bacterium as ISV. It was engineered with a blue-light response module (EL222) and self-luminous luminal hyaluronic acid (LHA) nanoparticles. Our study demonstrates that LHA generates local blue light stimulated by hydrogen peroxide, non-invasively activating the engineered Escherichia coli to produce IL-2. The engineered bacteria serve as an immunological adjuvant, promoting dendritic cell maturation, synergistically promoting T cell infiltration, and ultimately triggering a comprehensive activation of the immune system. Furthermore, when combined with the immune checkpoint inhibitor anti-PD-L1, this approach further effectively enhances cancer immunotherapy. Our results provide new strategies and promising prospects for the development of bacteria-based ISV immunotherapy. STATEMENT OF SIGNIFICANCE: This study developed a tumor microenvironment-activated nano-hybrid engineered bacteria (Ec-mIL2@LHA) as in situ vaccine for enhanced cancer immunotherapy. The LHA in bacterial vaccine non-invasively generated blue light upon stimulation by hydrogen peroxide of TME, leading to the sustained release of low-dose IL2 by engineered bacteria. In vitro and in vivo studies have demonstrated the bacterial in situ vaccine induced the immunogenic cell death and promote maturation of dendritic cells, ultimately triggering a comprehensive activation of anti-tumor immunity. After combination with anti-PD-L1, the bacterial in situ vaccine further effectively enhance cancer immunotherapy and inhibit metastasis. We provide a promising strategy to amplify antitumor immune effects by an engineered bacterial vaccine, showing potential clinical applications.

Nano drug delivery systems for advanced immune checkpoint blockade therapy

Immune checkpoint inhibitors (ICIs) have been widely utilized in the first-line therapy of various types of cancer. However, immune-related adverse events (irAEs) and resistance to ICIs remain intractable challenges for immune checkpoint blockade (ICB) therapy during clinic treatment. Nano drug delivery systems (NDDSs) have shown promising potential to improve anticancer efficacy and reduce side effects of small molecular drugs. The combination of nanotechnology and ICB provides new opportunities to overcome the challenges of immunotherapy. Nanoplatforms have been employed for direct delivery of ICIs, and they are preferred vehicles for combination therapy of ICIs and other therapeutic agents. In this review, the strategies of using NDDSs for advancing ICB therapy in recent years are surveyed, emphasizing the employment of NDDSs for combination treatment by ICIs and other agents to manipulate antitumor immunity. Analysis of current strategies for applying NDDSs for ICB leads to future research directions and development trends.

Extracellular Vesicle-Based Antitumor Nanomedicines

Extracellular vesicles (EVs) have emerged as promising bioactive carriers for delivering therapeutic agents, including nucleic acids, proteins, and small-molecule drugs, owing to their excellent physicochemical stability and biocompatibility. However, comprehensive reviews on the various types of EV-based nanomedicines for cancer therapy remain scarce. This review explores the potential of EVs as antitumor nanomedicines. Methods for EV extraction, drug loading, and engineering modifications are systematically examined, and the strengths and limitations of these technical approaches are critically assessed. Additionally, key strategies for developing EV-based antitumor therapies are highlighted. Finally, the opportunities and challenges associated with advancing EVs toward clinical translation are discussed. With the integration of multiple disciplines, robust EV-based therapeutic platforms are expected to be manufactured to provide more personalized and effective solutions for oncology patients.

Tailoring nanovectors for optimal neoantigen vaccine efficacy

The primary objective of neoantigen vaccines is to elicit a robust anti-tumor immune response by generating neoantigen-specific T cells that can eradicate tumor cells. Despite substantial advancements in personalized neoantigen prediction using next-generation sequencing, machine learning, and mass spectrometry, challenges remain in efficiently expanding neoantigen-specific T cell populations in vivo. This challenge impedes the widespread clinical application of neoantigen vaccines. Nanovector-based neoantigen delivery systems have emerged as a promising solutions to this challenge. These nanovectors offer several advantages, such as enhanced stability, targeted intracellular delivery, sustained release, and improved antigen-presenting cell (APC) activation. Notably, they effectively deliver various neoantigen vaccine formulations (DC cell-based, synthetic long peptide (SLP)-based or DNA/mRNA-based) to APCs or T cells, thereby activating both CD4+ T and CD8+ T cells. This ultimately induces a specific anti-tumor immune response. This review focuses on recent innovations in neoantigen vaccine delivery vectors. We aim to identify optimal design parameters for vectors tailored to different neoantigen vaccine types, with an emphasis on enhancing the tumor microenvironment and stimulating the production of neoantigen-specific cytotoxic T cells. By maximizing the potential of these delivery systems, we aim to accelerate the clinical translation of neoantigen nanovaccines and advance cancer immunotherapy.

Bacterial outer membrane vesicles in tumor prevention and treatment: advancements in research and application

As one of the major challenges to global health, the innovation of prevention and treatment methods for tumors has consistently been a focal point in medical research. In recent years, bacterial membrane vesicles (MVs), particularly outer membrane vesicles (OMVs) secreted by Gram-negative bacteria, have garnered significant attention due to their unique biological characteristics and potential anti-tumor effects. OMVs are bilayer lipid nanocapsules that are actively released by bacteria during their growth, typically ranging in diameter from 20 to 300 nm. They are rich in various biomolecules, including lipids, proteins, nucleic acids, and other small molecules. These components not only reflect the outer membrane structure of bacteria but also contain numerous pathogen-associated molecular patterns (PAMPs) related to bacterial pathogenicity and immunogenicity. Consequently, OMVs play an important role in bacterial resistance, antimicrobial activity, gene transfer, signal transduction, and immune regulation. Research and application of OMVs in anti-tumor therapy have made significant progress. This paper reviews the classification, characteristics, preparation, safety evaluation, biological functions, and specific research advancements of OMVs as antitumor drugs, immunomodulators, and carriers. Additionally, common methods for the preparation and modification of OMVs, including preliminary extraction, purification, characterization, and drug loading, are discussed. This paper also summarizes the challenges faced by OMVs in anti-tumor research and outlines future development directions, aiming to provide a reference for the further application of OMVs in tumor treatment.

Exosomes, their sources, and possible uses in cancer therapy in the era of personalized medicine

Despite significant advances in immunotherapy, its efficacy in solid tumors remains limited. Exosomes, a primary type of extracellular vesicles, can transport diverse intracellular molecules to nearby or distant cells and organs, facilitating numerous biological functions. Research has shown that exosomes have the dual ability to both activate and suppress the immune system. Their potential as anticancer vaccines arise from the capacity to carry antigens and major histocompatibility complex (MHC) molecules. Exosomes derived from blood, saliva, urine, and cerebrospinal fluid serve as promising biomarkers for cancer diagnosis and prognosis. Recent advancements in exosome-based therapy have highlighted its utility in drug delivery and immunotherapy. This review examines the composition and sources of exosomes within the immune microenvironment of solid tumors and delves into the mechanisms and pathways through which exosomes impact immunotherapy. We further explore the clinical potential of engineered exosomes and exosome vaccines in solid tumor immunotherapy. These insights may pave the way for exosome-based strategies in cancer diagnosis, treatment, and prognosis, enhancing the effectiveness of immunotherapy for solid tumors.

Protecting Against Postsurgery Oral Cancer Recurrence with an Implantable Hydrogel Vaccine for In Situ Photoimmunotherapy

Oral squamous cell carcinoma (OSCC) often recurs aggressively and metastasizes despite surgery and adjuvant therapy, driven by postoperative residual cancer cells near the primary tumor site. An implantable in situ vaccine hydrogel was designed to target residual OSCC cells post-tumor removal. This hydrogel serves as a reservoir for the sustained localized release of δ-aminolevulinic acid (δ-ALA), enhancing protoporphyrin IX-mediated photodynamic therapy (PDT), and a polydopamine-hyaluronic acid composite for photothermal therapy (PTT). Additionally, immune adjuvants, including anti-CD47 antibodies (aCD47) and CaCO3 nanoparticles, are directly released into the resected tumor bed. This approach induces apoptosis of residual OSCC cells through sequential near-infrared irradiation, promoting calcium interference therapy (CIT). The hydrogel further stimulates immunogenic cell death (ICD), facilitating the polarization of tumor-associated macrophages from the M2 to the M1 phenotype. This facilitates phagocytosis, dendritic cell activation, robust antigen presentation, and cytotoxic T lymphocyte-mediated cytotoxicity. In murine OSCC models, the in situ vaccine effectively prevents local recurrence, inhibits orthotopic OSCC growth and pulmonary metastases, and provides long-term protective immunity against tumor rechalle nge. These findings support postoperative in situ vaccination with a biocompatible hydrogel implant as a promising strategy to minimize residual tumor burden and reduce recurrence risk after OSCC resection.

Oral administration of Sophora Flavescens-derived exosomes-like nanovesicles carrying CX5461 ameliorates DSS-induced colitis in mice

Ulcerative colitis (UC) belongs to chronic inflammatory disease with a relapsing characterization. Conventional oral drugs of UC are restricted in clinical by premature degradation in the gastrointestinal tract, modest efficacy, and adverse effects. CX5461 can treat autoimmune disease, immunological rejection, and vascular inflammation. However, low solubility, intravenous administration, and non-inflammatory targeting limited its clinical application. Herein, this work aims to develop Sophora Flavescens-derived exosomes-like nanovesicles carrying CX5461 (SFELNVs@CX5461) for efficient CX5461 oral delivery for UC therapy. We identified SFELNVs as nano-diameter (80 nm) with negative zeta potential (-32mV). Cellular uptake has shown that SFELNVs were targeted uptake by macrophages, thus increasing drug concentration. Additionally, oral SFELNVs@CX5461 exhibited good safety and stability, as well as inflammation-targeting ability in the gastrointestinal tract of dextran sodium sulfate (DSS)-induced colitis mice. In vivo, oral administration of SFELNVs and CX5461 could relieve mice colitis. More importantly, combined SFELNVs and CX5461 alleviated mice colitis by inhibiting pro-inflammatory factors (TNF-α, IL-1β, and IL-6) expression and promoting M2 macrophage polarization. Furthermore, SFELNVs promoted M2 polarization by miR4371c using miRNA sequencing. Our results suggest that SFELNVs@CX5461 represents a novel orally therapeutic drug that can ameliorate colitis, and a promising targeting strategy for safe UC therapy.

Harnessing Bacterial Membrane Components for Tumor Vaccines: Strategies and Perspectives

Tumor vaccines stand at the vanguard of tumor immunotherapy, demonstrating significant potential and promise in recent years. While tumor vaccines have achieved breakthroughs in the treatment of cancer, they still encounter numerous challenges, including improving the immunogenicity of vaccines and expanding the scope of vaccine application. As natural immune activators, bacterial components offer inherent advantages in tumor vaccines. Bacterial membrane components, with their safer profile, easy extraction, purification, and engineering, along with their diverse array of immune components, activate the immune system and improve tumor vaccine efficacy. This review systematically summarizes the mechanism of action and therapeutic effects of bacterial membranes and its derivatives (including bacterial membrane vesicles and hybrid membrane biomaterials) in tumor vaccines. Subsequently, the authors delve into the preparation and advantages of tumor vaccines based on bacterial membranes and hybrid membrane biomaterials. Following this, the immune effects of tumor vaccines based on bacterial outer membrane vesicles are elucidated, and their mechanisms are explained. Moreover, their advantages in tumor combination therapy are analyzed. Last, the challenges and trends in this field are discussed. This comprehensive analysis aims to offer a more informed reference and scientific foundation for the design and implementation of bacterial membrane-based tumor vaccines.

Engineered probiotics with sustained release of interleukin-2 for the treatment of inflammatory bowel disease after oral delivery

Inflammatory bowel disease (IBD) is a kind of auto-immune disease characterized by disrupted intestinal barrier and mucosal epithelium, imbalanced gut microbiome and deregulated immune responses. Therefore, the restoration of immune equilibrium and gut microbiota could potentially serve as a hopeful approach for treating IBD. Herein, the oral probiotic Escherichia coli Nissle 1917 (ECN) was genetically engineered to express secretable interleukin-2 (IL-2), a kind of immunomodulatory agent, for the treatment of IBD. In our design, probiotic itself has the ability to regulate the gut microenvironment and IL-2 at low dose could selectively promote the generation of regulatory T cells to elicit tolerogenic immune responses. To improve the bioavailability of ECN expressing IL-2 (ECN-IL2) in the gastrointestinal tract, enteric coating Eudragit L100-55 was used to coat ECN-IL2, achieving significantly enhanced accumulation of engineered probiotics in the intestine. More importantly, L100-55 coated ECN-IL2 could effectively activated Treg cells to regulate innate immune responses and gut microbiota, thereby relieve inflammation and repair the colon epithelial barrier in dextran sodium sulfate (DSS) induced IBD. Therefore, genetically and chemically modified probiotics with excellent biocompatibility and efficiency in regulating intestinal microflora and intestinal inflammation show great potential for IBD treatment in the future.

Photodynamic Therapy Derived Personalized Whole Cell Tumor Vaccine Prevents Postsurgery Tumor Recurrence and Metastasis

In order to avoid the time-consuming and laborious identification of tumor-specific antigens (TSAs) during the traditional vaccine fabrication process, a versatile photodynamic therapy (PDT)-based method is developed to construct a whole-tumor antigen tumor vaccine (TV) from surgically resected tumor tissues for personalized immunotherapy. Mucoadhesive nanoparticles containing small-molecular photosensitizer are fabricated and directly co-incubated with suspended tumor cells obtained after cytoreduction surgery. After irradiation with a 405 nm laser, potent immunogenic cell death of cancer cells could be induced. Along with the release of TSAs, the as-prepared TV could activate safe and robust tumor-specific immune responses, leading to efficient suppression of postsurgery tumor recurrence and metastasis. The as-prepared TV cannot only be applied alone through various administration routes but also synergize with immunoadjuvant, chemotherapeutics, and immune checkpoint blockers to exert more potent immune responses. This work provides an alternative way to promote the clinical translation of PDT, which is generally restricted by the limited penetration of light. Moreover, the versatile strategy of vaccine fabrication also facilitates the clinical application of personalized whole-cell tumor vaccines.

Photosynthetic bacteria-based whole-cell inorganic-biohybrid system for multimodal enhanced tumor radiotherapy

The whole-cell inorganic-biohybrid systems show special functions and wide potential in biomedical application owing to the exceptional interactions between microbes and inorganic materials. However, the hybrid systems are still in stage of proof of concept. Here, we report a whole-cell inorganic-biohybrid system composed of Spirulina platensis and gold nanoclusters (SP-Au), which can enhance the cancer radiotherapy through multiple pathways, including cascade photocatalysis. Such systems can first produce oxygen under light irradiation, then convert some of the oxygen to superoxide anion (•O2-), and further oxidize the glutathione (GSH) in tumor cells. With the combination of hypoxic regulation, •O2- production, GSH oxidation, and the radiotherapy sensitization of gold nanoclusters, the final radiation is effectively enhanced, which show the best antitumor efficacy than other groups in both 4T1 and A549 tumor models. Moreover, in vivo distribution experiments show that the SP-Au can accumulate in the tumor and be rapidly metabolized through biodegradation, further indicating its application potential as a new multiway enhanced radiotherapy sensitizer.

Engineered biological nanoparticles as nanotherapeutics for tumor immunomodulation

Biological nanoparticles, or bionanoparticles, are small molecules manufactured in living systems with complex production and assembly machinery. The products of the assembly systems can be further engineered to generate functionalities for specific purposes. These bionanoparticles have demonstrated advantages such as immune system evasion, minimal toxicity, biocompatibility, and biological clearance. Hence, bionanoparticles are considered the new paradigm in nanoscience research for fabricating safe and effective nanoformulations for therapeutic purposes. Harnessing the power of the immune system to recognize and eradicate malignancies is a viable strategy to achieve better therapeutic outcomes with long-term protection from disease recurrence. However, cancerous tissues have evolved to become invisible to immune recognition and to transform the tumor microenvironment into an immunosuppressive dwelling, thwarting the immune defense systems and creating a hospitable atmosphere for cancer growth and progression. Thus, it is pertinent that efforts in fabricating nanoformulations for immunomodulation are mindful of the tumor-induced immune aberrations that could render cancer nanotherapy inoperable. This review systematically categorizes the immunosuppression mechanisms, the regulatory immunosuppressive cellular players, and critical suppressive molecules currently targeted as breakthrough therapies in the clinic. Finally, this review will summarize the engineering strategies for affording immune moderating functions to bionanoparticles that tip the tumor microenvironment (TME) balance toward cancer elimination, a field still in the nascent stage.

Outer membrane vesicles generated by an exogenous bacteriophage lysin and protection against Acinetobacter baumannii infection

BACKGROUND

The outer membrane vesicles (OMVs) produced by Gram-negative bacteria can modulate the immune system and have great potentials for bacterial vaccine development.

RESULTS

A highly active Acinetobacter baumannii phage lysin, LysP53, can stimulate the production of OMVs after interacting with A. baumannii, Escherichia coli, and Salmonella. The OMVs prepared by the lysin (LOMVs) from A. baumannii showed better homogeneity, higher protein yield, lower endotoxin content, and lower cytotoxicity compared to the naturally produced OMVs (nOMVs). The LOMVs contain a significantly higher number of cytoplasmic and cytoplasmic membrane proteins but a smaller number of periplasmic and extracellular proteins compared to nOMVs. Intramuscular immunization with either LOMVs or nOMVs three times provided robust protection against A. baumannii infections in both pneumonia and bacteremia mouse models. Intranasal immunization offered good protection in the pneumonia model but weaker protection (20-40%) in the bacteremia model. However, with a single immunization, LOMVs demonstrated better protection than the nOMVs in the pneumonia mouse model.

CONCLUSIONS

The novel lysin approach provides a superior choice compared to current methods for OMV production, especially for vaccine development.

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

Extracellular vesicles in cancer therapy: Roles, potential application, and challenges

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer as they play important roles in cancer development and progression. Considering their natural capacity to facilitate cell-to-cell communication as well as their high physiochemical stability and biocompatibility, EVs serve as superior delivery systems for a wide range of therapeutic agents, including medicines, nanomaterials, nucleic acids, and proteins. Therefore, EVs-based cancer therapy is of greater interest to researchers. Mounting studies indicate that EVs can be improved in efficiency, specificity, and safety for cancer therapy. However, their heterogeneity of physicochemical properties and functions is not fully understood, hindering the achievement of bioactive EVs with high yield and purity. Herein, we paid more attention to the EVs applications and their significance in cancer therapy.

Unveiling clinical applications of bacterial extracellular vesicles as natural nanomaterials in disease diagnosis and therapeutics

Bacterial extracellular vesicles (BEVs) are naturally occurring bioactive membrane-bound nanoparticles released by both gram-negative and gram-positive bacterial species, exhibiting a multifaceted role in mediating host-microbe interactions across various physiological conditions. Increasing evidence supports BEVs as essential mediators of cell-to-cell communicaiton, influencing bacterial pathogenicity, disease mechanisms, and modulating the host immune response. However, the extent to which these BEV-mediated actions can be leveraged to predict disease onset, guide treatment strategies, and determine clinical outcomes remains uncertain, particularly in terms of their clinical translation potentials. This review briefly describes BEV biogenesis and their internalisation by recipient cells and summarises methods for isolation and characterization, essential for understanding their composition and cargo. Further, it discusses the potential of biofluid-associated BEVs as biomarkers for various diseases, spanning both cancer and non-cancerous conditions. Following this, we outline the ongoing human clinical trials of using BEVs for vaccine development. In addition to disease diagnostics, this review explores the emerging research of using natural or engineered BEVs as smart nanomaterials for applications in anti-cancer therapy and bone regeneration. This discussion extends to key factors for unlocking the clinical potential of BEVs, such as standardization of BEV isolation and characterisation, as well as other hurdles in translating these findings to the clinical setting. We propose that addressing these hurdles through collaborative research efforts and well-designed clinical trials holds the key to fully harnessing the clinical potential of BEVs. As this field advances, this review suggests that BEV-based nanomedicine has the potential to revolutionize disease management, paving the way for innovative diagnosis, therapeutics, and personalized medicine approaches. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) from both host cells and bacteria serve as multifunctional biomaterials and are emerging in the fields of biomedicine, bioengineering, and biomaterials. However, the majority of current studies focus on host-derived EVs, leaving a gap in comprehensive research on bacteria-derived EVs (BEVs). Although BEVs offer an attractive option as nanomaterials for drug delivery systems, their unique nanostructure and easy-to-modify functions make them a potential method for disease diagnosis and treatment as well as vaccine development. Our work among the pioneering studies investigating the potential of BEVs as natural nanobiomaterials plays a crucial role in both understanding the development of diseases and therapeutic interventions.

Nanomaterial Delivery Vehicles for the Development of Neoantigen Tumor Vaccines for Personalized Treatment

Tumor vaccines have been considered a promising therapeutic approach for treating cancer in recent years. With the development of sequencing technologies, tumor vaccines based on neoantigens or genomes specifically expressed in tumor cells, mainly in the form of peptides, nucleic acids, and dendritic cells, are beginning to receive widespread attention. Therefore, in this review, we have introduced different forms of neoantigen vaccines and discussed the development of these vaccines in treating cancer. Furthermore, neoantigen vaccines are influenced by factors such as antigen stability, weak immunogenicity, and biosafety in addition to sequencing technology. Hence, the biological nanomaterials, polymeric nanomaterials, inorganic nanomaterials, etc., used as vaccine carriers are principally summarized here, which may contribute to the design of neoantigen vaccines for improved stability and better efficacy.

Roles of exosomes in immunotherapy for solid cancers

Although immunotherapy has made breakthrough progress, its efficacy in solid tumours remains unsatisfactory. Exosomes are the main type of extracellular vesicles that can deliver various intracellular molecules to adjacent or distant cells and organs, mediating various biological functions. Studies have found that exosomes can both activate the immune system and inhibit the immune system. The antigen and major histocompatibility complex (MHC) carried in exosomes make it possible to develop them as anticancer vaccines. Exosomes derived from blood, urine, saliva and cerebrospinal fluid can be used as ideal biomarkers in cancer diagnosis and prognosis. In recent years, exosome-based therapy has made great progress in the fields of drug transportation and immunotherapy. Here, we review the composition and sources of exosomes in the solid cancer immune microenvironment and further elaborate on the potential mechanisms and pathways by which exosomes influence immunotherapy for solid cancers. Moreover, we summarize the potential clinical application prospects of engineered exosomes and exosome vaccines in immunotherapy for solid cancers. Eventually, these findings may open up avenues for determining the potential of exosomes for diagnosis, treatment, and prognosis in solid cancer immunotherapy.

PD-L1-Expressing Extracellular Vesicles for the Treatment of Pneumonia

Acute respiratory distress syndrome (ARDS) is a severe lung condition with a high mortality rate and a lack of effective drug therapy. In this work, we developed mesenchymal stem cell (MSC)-derived extracellular vesicles with high PD-L1 expression (MSC-EVs-PD-L1) for treating lipopolysaccharide (LPS)-induced pneumonia by intratracheal administration. We found an upregulation of PD-1 expression in the inflammatory region of murine lungs; hence, MSC-EVs-PD-L1 exerted immunosuppressive effects via the PD-1/PD-L1 signaling pathway. Furthermore, we treated LPS-induced pneumonia mice by intratracheal administration, which enabled heavy drug accumulation in the lungs of mice and better therapeutic efficacy compared to systemic administration. Our results suggest that MSC-EVs-PD-L1 has the potential to provide a universal platform technology for the immunotherapy of pneumonia.

Advances in immunotyping of colorectal cancer

Immunotherapy has transformed treatment for various types of malignancy. However, the benefit of immunotherapy is limited to a minority of patients with mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) (dMMR-MSI-H) colorectal cancer (CRC). Understanding the complexity and heterogeneity of the tumor immune microenvironment (TIME) and identifying immune-related CRC subtypes will improve antitumor immunotherapy. Here, we review the current status of immunotherapy and typing schemes for CRC. Immune subtypes have been identified based on TIME and prognostic gene signatures that can both partially explain clinical responses to immune checkpoint inhibitors and the prognosis of patients with CRC. Identifying immune subtypes will improve understanding of complex CRC tumor heterogeneity and refine current immunotherapeutic strategies.

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.

Rethinking Antigen Source: Cancer Vaccines Based on Whole Tumor Cell/tissue Lysate or Whole Tumor Cell

Cancer immunotherapies have improved human health, and one among the important technologies for cancer immunotherapy is cancer vaccine. Antigens are the most important components in cancer vaccines. Generally, antigens in cancer vaccines can be divided into two categories: pre-defined antigens and unidentified antigens. Although, cancer vaccines loaded with predefined antigens are commonly used, cancer vaccine loaded with mixed unidentified antigens, especially whole cancer cells or cancer cell lysates, is a very promising approach, and such vaccine can obviate some limitations in cancer vaccines. Their advantages include, but are not limited to, the inclusion of pan-spectra (all or most kinds of) antigens, inducing pan-clones specific T cells, and overcoming the heterogeneity of cancer cells. In this review, the recent advances in cancer vaccines based on whole-tumor antigens, either based on whole cancer cells or whole cancer cell lysates, are summarized. In terms of whole cancer cell lysates, the focus is on applying whole water-soluble cell lysates as antigens. Recently, utilizing the whole cancer cell lysates as antigens in cancer vaccines has become feasible. Considering that pre-determined antigen-based cancer vaccines (mainly peptide-based or mRNA-based) have various limitations, developing cancer vaccines based on whole-tumor antigens is a promising alternative.

Ultrasound Responsive Nanovaccine Armed with Engineered Cancer Cell Membrane and RNA to Prevent Foreseeable Metastasis

Cancer vaccine has been considered as a promising immunotherapy by inducing specific anti-tumor immune response. Rational vaccination at suitable time to efficiently present tumor associated antigen will boost tumor immunity and is badly needed. Here, a poly (lactic-co-glycolic acid) (PLGA)-based cancer vaccine of nanoscale is designed, in which engineered tumor cell membrane proteins, mRNAs, and sonosensitizer chlorin e6 (Ce6) are encapsulated at high efficiency. The nanosized vaccine can be efficiently delivered into antigen presentation cells (APCs) in lymph nodes after subcutaneous injection. In the APCs, the encapsulated cell membrane and RNA from engineered cells, which have disturbed splicing resembling the metastatic cells, provide neoantigens of metastatic cancer in advance. Moreover, the sonosensitizer Ce6 together with ultrasound irradiation promotes mRNA escape from endosome, and augments antigen presentation. Through 4T1 syngeneic mouse model, it has been proved that the proposed nanovaccine is efficient to elicit antitumor immunity and thus prevent cancer metastasis.

Biomimetic Cell-Derived Nanoparticles: Emerging Platforms for Cancer Immunotherapy

Cancer immunotherapy can significantly prevent tumor growth and metastasis by activating the autoimmune system without destroying normal cells. Although cancer immunotherapy has made some achievements in clinical cancer treatment, it is still restricted by systemic immunotoxicity, immune cell dysfunction, cancer heterogeneity, and the immunosuppressive tumor microenvironment (ITME). Biomimetic cell-derived nanoparticles are attracting considerable interest due to their better biocompatibility and lower immunogenicity. Moreover, biomimetic cell-derived nanoparticles can achieve different preferred biological effects due to their inherent abundant source cell-relevant functions. This review summarizes the latest developments in biomimetic cell-derived nanoparticles for cancer immunotherapy, discusses the applications of each biomimetic system in cancer immunotherapy, and analyzes the challenges for clinical transformation.