William B. Coley: His Hypothesis, His Toxin, and the Birth of Immunotherapy

Reprogramming a Doxycycline-Inducible Gene Switch System for Bacteria-Mediated Cancer Therapy

PURPOSE

Attenuated Salmonella typhimurium is a potential biotherapeutic antitumor agent because it can colonize tumors and inhibit their growth. The present study aimed to develop a doxycycline (Doxy)-inducible gene switch system in attenuated S. typhimurium and assess its therapeutic efficacy in various tumor-bearing mice models.

PROCEDURES

A Doxy-inducible gene switch system comprising two plasmids was engineered to trigger the expression of cargo genes (Rluc8 and clyA). Attenuated S. typhimurium carrying Rluc8 were injected intravenously into BALB/c mice bearing CT26 tumors, and bioluminescence images were captured at specified intervals post-administration of doxycycline. The tumor-suppressive effects of bacteria carrying clyA were evaluated in BALB/c mice bearing CT26 tumors and in C57BL/6 mice bearing MC38 tumors.

RESULTS

Expression of the fimE gene, induced only in the presence of Doxy, triggered a unidirectional switch of the POXB20 promoter to induce expression of the cargo genes. The switch event was maintained over a long period of bacterial culture. After intravenous injection of transformed Salmonella into mice bearing CT26 tumors, the bacteria transformed with the Doxy-inducible gene switch system for Rluc8 targeted only tumor tissues and expressed the payloads 2 days after Doxy treatment. Notably, bacteria carrying the Doxy-inducible gene switch system for clyA effectively suppressed tumor growth and prolonged survival, even after just one Doxy induction.

CONCLUSIONS

These results suggest that attenuated S. typhimurium carrying this novel gene switch system elicited significant therapeutic effects through a single induction triggering and were a potential biotherapeutic agent for tumor therapy.

Bacteria-Based Nanoprobes for Cancer Therapy

Surgical removal together with chemotherapy and radiotherapy has used to be the pillars of cancer treatment. Although these traditional methods are still considered as the first-line or standard treatments, non-operative situation, systemic toxicity or resistance severely weakened the therapeutic effect. More recently, synthetic biological nanocarriers elicited substantial interest and exhibited promising potential for combating cancer. In particular, bacteria and their derivatives are omnipotent to realize intrinsic tumor targeting and inhibit tumor growth with anti-cancer agents secreted and immune response. They are frequently employed in synergistic bacteria-mediated anticancer treatments to strengthen the effectiveness of anti-cancer treatment. In this review, we elaborate on the development, mechanism and advantage of bacterial therapy against cancer and then systematically introduce the bacteria-based nanoprobes against cancer and the recent achievements in synergistic treatment strategies and clinical trials. We also discuss the advantages as well as the limitations of these bacteria-based nanoprobes, especially the questions that hinder their application in human, exhibiting this novel anti-cancer endeavor comprehensively.

Revisiting Coley's Toxins: Immunogenic Cardiolipins from Streptococcus pyogenes

Coley's toxins, an early and enigmatic form of cancer (immuno)therapy, were based on preparations of Streptococcus pyogenes. As part of a program to explore bacterial metabolites with immunomodulatory potential, S. pyogenes metabolites were assayed in a cell-based immune assay, and a single membrane lipid, 18:1/18:0/18:1/18:0 cardiolipin, was identified. Its activity was profiled in additional cellular assays, which showed it to be an agonist of a TLR2-TLR1 signaling pathway with a 6 μM EC50 and robust TNF-α induction. A synthetic analog with switched acyl chains had no measurable activity in immune assays. The identification of a single immunogenic cardiolipin with a restricted structure-activity profile has implications for immune regulation, cancer immunotherapy, and poststreptococcal autoimmune diseases.

Research progress of nanovaccine in anti-tumor immunotherapy

Tumor vaccines aim to activate dormant or unresponsive tumor-specific T lymphocytes by using tumor-specific or tumor-associated antigens, thus enhancing the body's natural defense against cancer. However, the effectiveness of tumor vaccines is limited by the presence of tumor heterogeneity, low immunogenicity, and immune evasion mechanisms. Fortunately, multifunctional nanoparticles offer a unique chance to address these issues. With the advantages of their small size, high stability, efficient drug delivery, and controlled surface chemistry, nanomaterials can precisely target tumor sites, improve the delivery of tumor antigens and immune adjuvants, reshape the immunosuppressive tumor microenvironment, and enhance the body's anti-tumor immune response, resulting in improved efficacy and reduced side effects. Nanovaccine, a type of vaccine that uses nanotechnology to deliver antigens and adjuvants to immune cells, has emerged as a promising strategy for cancer immunotherapy due to its ability to stimulate immune responses and induce tumor-specific immunity. In this review, we discussed the compositions and types of nanovaccine, and the mechanisms behind their anti-tumor effects based on the latest research. We hope that this will provide a more scientific basis for designing tumor vaccines and enhancing the effectiveness of tumor immunotherapy.

E. coli Phagelysate: A Primer to Enhance Nanoparticles and Drug Deliveries in Tumor

The tumor microenvironment (TME), where cancer cells reside, plays a crucial role in cancer progression and metastasis. It maintains an immunosuppressive state in many tumors and regulates the differentiation of precursor monocytes into M1 (anti-tumor)- and M2 (pro-tumor)-polarized macrophages, and greatly reduces anticancer drug and nanoparticle delivery. As a result, the effectiveness of recently developed chemo- and/or nanotechnology-mediated immune and magnetic nanoparticle hyperthermia (mNPH) therapies is inhibited significantly. One of the ways to overcome this limitation is to use E. coli phagelysate as a primer to modify the tumor microenvironment by switching tumor-associated M2 macrophages to anti-tumor M1 macrophages, and initiate the infiltration of tumor-associated macrophages (TAMs). Recently, bacteriophages and phage-induced lysed bacteria (bacterial phagelysates-BPLs) have been shown to be capable of modifying the tumor-associated environment. Phage/BPL-coated proteins tend to elicit strong anti-tumor responses from the innate immune system, prompting phagocytosis and cytokine release. It has also been reported that the microenvironments of bacteriophage- and BPL-treated tumors facilitate the conversion of M2-polarized TAMS to a more M1-polarized (tumoricidal) environment post-phage treatment. This paper demonstrates the feasibility and enhanced efficacy of combining E. coli phagelysate (EcPHL) and mNPH, a promising technology for treating cancers, in a rodent model. Specifically, we illustrate the EcPHL vaccination effect on the TME and mNP distribution in Ehrlich adenocarcinoma tumors by providing the tumor growth dynamics and histology (H&E and Prussian blue) distribution of mNP in tumor and normal tissue.

Fusobacterium nucleatum and cancer

Accumulating evidence demonstrates that the oral pathobiont Fusobacterium nucleatum is involved in the progression of an increasing number of tumors types. Thus far, the mechanisms underlying tumor exacerbation by F. nucleatum include the enhancement of proliferation, establishment of a tumor‐promoting immune environment, induction of chemoresistance, and the activation of immune checkpoints. This review focuses on the mechanisms that mediate tumor‐specific colonization by fusobacteria. Elucidating the mechanisms mediating fusobacterial tumor tropism and promotion might provide new insights for the development of novel approaches for tumor detection and treatment.

Effective Combinations of Immunotherapy and Radiotherapy for Cancer Treatment

Though single tumor immunotherapy and radiotherapy have significantly improved the survival rate of tumor patients, there are certain limitations in overcoming tumor metastasis, recurrence, and reducing side effects. Therefore, it is urgent to explore new tumor treatment methods. The new combination of radiotherapy and immunotherapy shows promise in improving therapeutic efficacy and reducing recurrence by enhancing the ability of the immune system to recognize and eradicate tumor cells, to overcome tumor immune tolerance mechanisms. Nanomaterials, as new drug-delivery-system materials of the 21st century, can maintain the activity of drugs, improve drug targeting, and reduce side effects in tumor immunotherapy. Additionally, nanomaterials, as radiosensitizers, have shown great potential in tumor radiotherapy due to their unique properties, such as light, heat, electromagnetic effects. Here, we review the mechanisms of tumor immunotherapy and radiotherapy and the synergy of radiotherapy with multiple types of immunotherapies, including immune checkpoint inhibitors (ICIs), tumor vaccines, adoptive cell therapy, and cytokine therapy. Finally, we propose the potential for nanomaterials in tumor radiotherapy and immunotherapy.

Current status of immunotherapy for non-small cell lung cancer

Nowadays, lung cancer is still the deadliest oncological disease in the world. Among them, non-small cell lung cancer (NSCLC) accounts for 80%∼85% of all lung cancers, and its 5-year survival rate is less than 15%, making the situation critical. In the past decades, despite some clinical advances in conventional treatments, the overall survival rate of NSCLC is still not optimistic due to its unique physiological conditions and the frequent occurrence of tumor escape. In recent years, immunotherapy has become a new hot spot in lung cancer research, including antibody therapy and cell therapy, which have been developed and utilized one after another, especially immune checkpoint inhibitor (ICI). These approaches have effectively improved the overall survival rate and objective response rate of NSCLC patients by enhancing the immune capacity of the body and targeting tumor cells more effectively, which is more specific and less toxic compared with conventional chemotherapy, and providing more strategies for NSCLC treatment. In this paper, we reviewed the relevant targets, clinical progress and adverse reaction in monoclonal antibodies, antibody-drug conjugates, ICI, bispecific antibodies, T-cell receptor engineered T cell therapy (TCR-T), Chimeric antigen receptor T-cell immunotherapy (CAR-T), and also report on their combination therapy from the immune-related background to provide better NSCLC treatment and prospective.