A BCG success story: From prevention of tuberculosis to optimal bladder cancer treatment

BCG and bladder cancer. Forty-eight years after Morales report

Although BCG use as an anticancer drug was nearly abandoned due to the poor results in most tumors, in 1976 Morales reported a relevant reduction in recurrence with intravesical BCG in few patients affected by NMIBC. Since then BCG was globally accepted as an empirical and effective therapy in treating Tis and preventing recurrence of intermediate and high risk NMIBC. Forty-eight years after Morales' report, although some open questions remain object of debate, we have been able to find answers to many doubts improving BCG activity and toxicity. We better select patients undergoing BCG and many trials have indicated the best dosage and schedule. Moreover, we are able to better identify the patient unresponsive to BCG who might benefit of a timely radical cystectomy. We are also aware of the difficulties and toxicities that can be encountered with BCG use in every-day clinical practice. Research is ongoing to obtain genetically modified BCG to increase its efficacy and reduce toxicity. Moreover, the combination of BCG with other immunotherapeutic drugs given intravesically or systemically, first immune checkpoint inhibitors, is under study to obtain a response in patients unresponsive or intolerant to BCG. Almost 50 years after Morales publication, intravesical BCG remains an inalienable tool against NMIBC.

Friend or Foe: Exploring the Relationship between the Gut Microbiota and the Pathogenesis and Treatment of Digestive Cancers

Digestive cancers are among the leading causes of cancer death in the world. However, the mechanisms of cancer development and progression are not fully understood. Accumulating evidence in recent years pointing to the bidirectional interactions between gut dysbiosis and the development of a specific type of gastrointestinal cancer is shedding light on the importance of this "unseen organ"-the microbiota. This review focuses on the local role of the gut microbiota imbalance in different digestive tract organs and annexes related to the carcinogenic mechanisms. Microbiota modulation, either by probiotic administration or by dietary changes, plays an important role in the future therapies of various digestive cancers.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Carcinoma In Situ (CIS): Is There a Difference in Efficacy between Various BCG Strains? A Comprehensive Review of the Literature

Introduction: Intravesical Bacillus Calmette-Guérin (BCG) immunotherapy is the standard of care for high-risk and intermediate-risk non-muscle-invasive bladder cancer (NMIBC) as well as for Carcinoma in situ (CIS). Evidence supports that the different BCG strains, despite genetic variability, are equally effective clinically for preventing the recurrence and progression of papillary NMIBC. The available evidence regarding possible differences in clinical efficacy between various BCG strains in CIS is lacking. Methods: We reviewed the literature on the efficacy of different BCG strains in patients with CIS (whether primary, secondary, concomitant, or unifocal/multifocal), including randomized clinical trials (RCTs), phase II/prospective trials, and retrospective studies with complete response rates (CRR), recurrence-free survival (RFS), or progression-free survival (PFS) as endpoints. Results: In most studies, being RCTs, phase II prospective trials, or retrospective studies, genetic differences between BCG strains did not translate into meaningful differences in clinical efficacy against CIS, regardless of the CIS subset (primary, secondary, or concurrent) or CIS focality (unifocal or multifocal). CRR, RFS, and PFS were not statistically different between various BCG strains. None of these trials were designed as head-to-head comparisons between BCG strains focusing specifically on CIS. Limitations include the small sample size of many studies and most comparisons between strains being indirect rather than head-to-head. Conclusions: This review suggests that the clinical efficacy of the various BCG strains appears similar, irrespective of CIS characteristics. However, based on the weak level of evidence available and underpowered studies, randomized studies in this space should be encouraged as no definitive conclusion can be drawn at this stage.

Intratumoral Influenza Vaccine Administration Attenuates Breast Cancer Growth and Restructures the Tumor Microenvironment through Sialic Acid Binding of Vaccine Hemagglutinin

Breast cancer continues to have a high disease burden worldwide and presents an urgent need for novel therapeutic strategies to improve outcomes. The influenza vaccine offers a unique approach to enhance the anti-tumor immune response in patients with breast cancer. Our study explores the intratumoral use of the influenza vaccine in a triple-negative 4T1 mouse model of breast cancer. We show that the influenza vaccine attenuated tumor growth using a three-dose intratumoral regimen. More importantly, prior vaccination did not alter this improved anti-tumor response. Furthermore, we characterized the effect that the influenza vaccine has on the tumor microenvironment and the underlying mechanisms of action. We established that the vaccine facilitated favorable shifts in restructuring the tumor microenvironment. Additionally, we show that the vaccine's ability to bind sialic acid residues, which have been implicated in having oncogenic functions, emerged as a key mechanism of action. Influenza hemagglutinin demonstrated binding ability to breast cancer cells through sialic acid expression. When administered intratumorally, the influenza vaccine offers a promising therapeutic strategy for breast cancer patients by reshaping the tumor microenvironment and modestly suppressing tumor growth. Its interaction with sialic acids has implications for effective therapeutic application and future research.

Trained immunity: Target for prophylaxis and therapy

Trained immunity is a de facto memory for innate immune responses, leading to long-term functional reprogramming of innate immune cells. In physiological conditions, trained immunity leads to adaptive states that enhance resistance against pathogens and contributes to immunosurveillance. Dysregulated trained immunity can however lead either to defective innate immune responses in severe infections or cancer or to inflammatory and autoimmune diseases if trained immunity is inappropriately activated. Here, we review the immunological and molecular mechanisms that mediate trained immunity induction and propose that trained immunity represents an important target for prophylactic and therapeutic approaches in human diseases. On the one hand, we argue that novel approaches that induce trained immunity may enhance vaccine efficacy. On the other hand, induction of trained immunity in cancer, and inhibition of exaggerated induction of trained immunity in inflammatory disorders, are viable targets amenable for new therapeutic approaches.

Does Early Childhood BCG Vaccination Improve Survival to Midlife in a Population With a Low Tuberculosis Prevalence? Quasi-experimental Evidence on Nonspecific Effects From 32 Swedish Birth Cohorts

The Bacillus Calmette-Guérin (BCG) vaccine for tuberculosis (TB) is widely used globally. Many high-income countries discontinued nationwide vaccination policies starting in the 1980s as the TB prevalence decreased. However, there is continued scientific interest in whether the general childhood immunity boost conferred by the BCG vaccination impacts adult health and mortality in low-TB contexts (known as nonspecific effects). While recent studies have found evidence of an association between BCG vaccination and survival to ages 34-45, it is unclear whether these associations are causal or driven by the unobserved characteristics of those who chose to voluntarily vaccinate. We use the abrupt discontinuation of mandatory BCG vaccination in Sweden in 1975 as a natural experiment to estimate the causal nonspecific effect of the BCG vaccine on cohort survival to midlife. Applying two complementary study designs, we find no evidence that survival to age 40 was affected by the discontinuation of childhood BCG vaccination. The results are consistent among both males and females and are robust to several sensitivity tests. Overall, despite prior correlational studies suggesting large nonspecific effects, we do not find any population-level evidence for a nonspecific effect of the BCG vaccine discontinuation on survival to age 40 in Sweden.

Using bugs as drugs: administration of bacteria-related microbes to fight cancer

Driven by the advancement of microbiology and cancer biology, bioengineering of bacteria-related microbes has demonstrated great potential in targeted cancer therapy. Presently, the major administration routes of bacteria-related microbes for cancer treatment include intravenous injection, intratumoral injection, intraperitoneal injection, and oral delivery. Administration routes of bacteria play a key role in anticancer therapeutic efficacy since different delivery approaches might exert an anticancer effect through diverse mechanisms. Herein, we provide an overview of the primary routes of bacteria administration as well as their advantages and limitations. Furthermore, we discuss that microencapsulation can overcome the current challenges of direct administration of free bacteria. We also review the latest advancements in combining functional particles with engineered bacteria to fight against cancer, which can be further coupled with conventional anticancer therapies to improve the therapeutic effect. Eventually, we highlight the application prospect of bioprinting in cancer bacteriotherapy, which enables the long-term sustained delivery and individualized dose regimen, representing a new paradigm for personalized cancer treatment.

Does Therapeutic Repurposing in Cancer Meet the Expectations of Having Drugs at a Lower Price?

Therapeutic repurposing emerged as an alternative to the traditional drug discovery and development model (DDD) of new molecular entities (NMEs). It was anticipated that by being faster, safer, and cheaper, the development would result in lower-cost drugs. As defined in this work, a repurposed cancer drug is one approved by a health regulatory authority against a non-cancer indication that then gains new approval for cancer. With this definition, only three drugs are repurposed for cancer: Bacillus Calmette-Guerin (BCG) vaccine (superficial bladder cancer, thalidomide [multiple myeloma], and propranolol [infantile hemangioma]). Each of these has a different history regarding price and affordability, and it is not yet possible to generalize the impact of drug repurposing on the final price to the patient. However, the development, including the price, does not differ significantly from an NME. For the end consumer, the product's price is unrelated to whether it followed the classical development or repurposing. Economic constraints for clinical development, and drug prescription biases for repurposing drugs, are barriers yet to be overcome. The affordability of cancer drugs is a complex issue that varies from country to country. Many alternatives for having affordable drugs have been put forward, however these measures have thus far failed and are, at best, palliative. There are no immediate solutions to the problem of access to cancer drugs. It is necessary to critically analyze the impact of the current drug development model and be creative in implementing new models that genuinely benefit society.

Synergistic potential of immune checkpoint inhibitors and therapeutic cancer vaccines

Cancer vaccines and immune checkpoint inhibitors (ICIs) function at different stages of the cancer immune cycle due to their distinct mechanisms of action. Therapeutic cancer vaccines enhance the activation and infiltration of cytotoxic immune cells into the tumor microenvironment (TME), while ICIs, prevent and/or reverse the dysfunction of these immune cells. The efficacy of both classes of immunotherapy has been evaluated in monotherapy, but they have been met with several challenges. Although therapeutic cancer vaccines can activate anti-tumor immune responses, these responses are susceptible to attenuation by immunoregulatory molecules. Similarly, ICIs are ineffective in the absence of tumor-infiltrating lymphocytes (TILs). Further, ICIs are often associated with immune-related adverse effects that may limit quality of life and compliance. However, the combination of the improved immunogenicity afforded by cancer vaccines and restrained immunosuppression provided by immune checkpoint inhibitors may provide a suitable platform for therapeutic synergism. In this review, we revisit the history and various classifications of therapeutic cancer vaccines. We also provide a summary of the currently approved ICIs. Finally, we provide mechanistic insights into the synergism between ICIs and cancer vaccines.

Positron Emission Tomography Probes for Imaging Cytotoxic Immune Cells

Non-invasive positron emission tomography (PET) imaging of immune cells is a powerful approach for monitoring the dynamics of immune cells in response to immunotherapy. Despite the clinical success of many immunotherapeutic agents, their clinical efficacy is limited to a subgroup of patients. Conventional imaging, as well as analysis of tissue biopsies and blood samples do not reflect the complex interaction between tumour and immune cells. Consequently, PET probes are being developed to capture the dynamics of such interactions, which may improve patient stratification and treatment evaluation. The clinical efficacy of cancer immunotherapy relies on both the infiltration and function of cytotoxic immune cells at the tumour site. Thus, various immune biomarkers have been investigated as potential targets for PET imaging of immune response. Herein, we provide an overview of the most recent developments in PET imaging of immune response, including the radiosynthesis approaches employed in their development.

Highlights of the 3rd international BCG symposium: 100th anniversary of the first administration of BCG

2021 was the year of the 100th anniversary of the first administration of the Bacillus Calmette-Guérin (BCG) to a human being. It was the start of a long journey of the world’s most widely used vaccine and the oldest vaccine still in use. More than 4 billion children have been vaccinated with BCG for protection against tuberculosis. However, over the years it became apparent that BCG also has beneficial non-specific effects. As such, it provides protection against various heterologous infectious and non-infectious diseases and is used to treat non-muscle-invasive bladder cancer. As BCG was developed at the Institut Pasteur de Lille by Albert Calmette and Camille Guérin, the Institute has celebrated this important anniversary with an international scientific symposium on all aspects of BCG, held from November 17 to 19, 2021 at the Institut Pasteur de Lille. It covered BCG against tuberculosis and described novel vaccine approaches, the effect of BCG against heterologous infections, including BCG and COVID-19, the effect of BCG against cancer, and BCG against auto-immune and inflammatory diseases. To discuss these areas, the symposium gathered close to 200 participants from all five continents, 2/3 on-line. This article presents the highlights of this 3^rd International Symposium on BCG.

Progressive Host-Directed Strategies to Potentiate BCG Vaccination Against Tuberculosis

The pursuit to improve the TB control program comprising one approved vaccine, M. bovis Bacille Calmette-Guerin (BCG) has directed researchers to explore progressive approaches to halt the eternal TB pandemic. Mycobacterium tuberculosis (M.tb) was first identified as the causative agent of TB in 1882 by Dr. Robert Koch. However, TB has plagued living beings since ancient times and continues to endure as an eternal scourge ravaging even with existing chemoprophylaxis and preventive therapy. We have scientifically come a long way since then, but despite accessibility to the standard antimycobacterial antibiotics and prophylactic vaccine, almost one-fourth of humankind is infected latently with M.tb. Existing therapeutics fail to control TB, due to the upsurge of drug-resistant strains and increasing incidents of co-infections in immune-compromised individuals. Unresponsiveness to established antibiotics leaves patients with no therapeutic possibilities. Hence the search for an efficacious TB immunization strategy is a global health priority. Researchers are paving the course for efficient vaccination strategies with the radically advanced operation of core principles of protective immune responses against M.tb. In this review; we have reassessed the progression of the TB vaccination program comprising BCG immunization in children and potential stratagems to reinforce BCG-induced protection in adults.

The Role of The Tumor Microbiome in Tumor Development and Its Treatment

Commensal bacteria and other microorganisms that reside in the human body are closely associated with the development and treatment of cancers. Recently, tumor microbiome (TM) has been identified in a variety of cancers such as pancreatic, lung, and breast cancers. TM has different compositions in different tumors and has different effects on tumors. TM plays an important role in the formation of the tumor microenvironment, regulation of local immunity, and modification of tumor cell biology, and directly affects the efficacy of drug treatment for tumors. TM is expected to be a biomarker for tumors, and engineered tumor-targeting bacteria and anti-cancer microbial agents (GEN-001) have an important role in the treatment of tumors. This paper reviews the relevant studies on TM in recent years and describes its distribution in different tumors, its correlation with clinical features, its effect on local immunity, and the research directions of TM in tumor treatment.

Recombinant BCG to Enhance Its Immunomodulatory Activities

The bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium bovis derivative that has been widely used as a live vaccine against tuberculosis for a century. In addition to its use as a tuberculosis vaccine, BCG has also been found to have utility in the prevention or treatment of unrelated diseases, including cancer. However, the protective and therapeutic efficacy of BCG against tuberculosis and other diseases is not perfect. For three decades, it has been possible to genetically modify BCG in an attempt to improve its efficacy. Various immune-modulatory molecules have been produced in recombinant BCG strains and tested for protection against tuberculosis or treatment of several cancers or inflammatory diseases. These molecules include cytokines, bacterial toxins or toxin fragments, as well as other protein and non-protein immune-modulatory molecules. The deletion of genes responsible for the immune-suppressive properties of BCG has also been explored for their effect on BCG-induced innate and adaptive immune responses. Most studies limited their investigations to the description of T cell immune responses that were modified by the genetic modifications of BCG. Some studies also reported improved protection by recombinant BCG against tuberculosis or enhanced therapeutic efficacy against various cancer forms or allergies. However, so far, these investigations have been limited to mouse models, and the prophylactic or therapeutic potential of recombinant BCG strains has not yet been illustrated in other species, including humans, with the exception of a genetically modified BCG strain that is now in late-stage clinical development as a vaccine against tuberculosis. In this review, we provide an overview of the different molecular engineering strategies adopted over the last three decades in order to enhance the immune-modulatory potential of BCG.

Graphene Oxide and Graphene Quantum Dots as Delivery Systems of Cationic Porphyrins: Photo-Antiproliferative Activity Evaluation towards T24 Human Bladder Cancer Cells

The development of new photodynamic therapy (PDT) agents designed for bladder cancer (BC) treatments is of utmost importance to prevent its recurrence and progression towards more invasive forms. Here, three different porphyrinic photosensitizers (PS) (TMPyP, Zn-TMPyP, and P1-C₅) were non-covalently loaded onto graphene oxide (GO) or graphene quantum dots (GQDs) in a one-step process. The cytotoxic effects of the free PS and of the corresponding hybrids were compared upon blue (BL) and red-light (RL) exposure on T24 human BC cells. In addition, intracellular reactive oxygen species (ROS) and singlet oxygen generation were measured. TMPyP and Zn-TMPyP showed higher efficiency under BL (IC₅₀: 0.42 and 0.22 μm, respectively), while P1-C₅ was more active under RL (IC₅₀: 0.14 μm). In general, these PS could induce apoptotic cell death through lysosomes damage. The in vitro photosensitizing activity of the PS was not compromised after their immobilization onto graphene-based nanomaterials, with Zn-TMPyP@GQDs being the most promising hybrid system under RL (IC₅₀: 0.37 μg/mL). Overall, our data confirm that GO and GQDs may represent valid platforms for PS delivery, without altering their performance for PDT on BC cells.