Mycobacteria emulsified in olive oil-in-water trigger a robust immune response in bladder cancer treatment

Mycobacteria Treatment Inhibits Bladder Cancer Cell Migration, Invasion, and Anchorage-Independent Growth

Bladder cancer (BC) is a highly recurrent and invasive malignancy, with Mycobacterium bovis BCG serving as the primary immunotherapy, particularly for non-muscle-invasive bladder cancer (NMIBC). However, the mechanisms underlying BCG's antitumor effects and the potential of non-tuberculous mycobacteria like Mycobacterium brumae remain unclear. This study investigates the antitumor effects of M. bovis BCG and M. brumae on BC cell migration, invasion, and anchorage-independent growth. BC cell lines representing different stages of tumor differentiation were treated with either M. bovis BCG or M. brumae. Cell migration was assessed through wound healing and transwell assays, invasiveness by transwell invasion assays, MMP-9 production by gelatin zymography, and anchorage-independent growth via soft agar colony formation. Both mycobacteria inhibited individual cell migration across all BC lines, while collective migration was only reduced in intermediate-grade cells. Both treatments also reduced invasiveness, associated with decreased MMP-9 production. Furthermore, M. brumae inhibited anchorage-independent growth across all BC lines, while M. bovis BCG had a more selective effect, primarily inhibiting growth in high-grade cells. In conclusion, both mycobacteria reduce migration, invasion, and anchorage-independent growth of BC cells, with their effectiveness varying by species and tumor differentiation grade.

Urease-powered nanobots for radionuclide bladder cancer therapy

Bladder cancer treatment via intravesical drug administration achieves reasonable survival rates but suffers from low therapeutic efficacy. To address the latter, self-propelled nanoparticles or nanobots have been proposed, taking advantage of their enhanced diffusion and mixing capabilities in urine when compared with conventional drugs or passive nanoparticles. However, the translational capabilities of nanobots in treating bladder cancer are underexplored. Here, we tested radiolabelled mesoporous silica-based urease-powered nanobots in an orthotopic mouse model of bladder cancer. In vivo and ex vivo results demonstrated enhanced nanobot accumulation at the tumour site, with an eightfold increase revealed by positron emission tomography in vivo. Label-free optical contrast based on polarization-dependent scattered light-sheet microscopy of cleared bladders confirmed tumour penetration by nanobots ex vivo. Treating tumour-bearing mice with intravesically administered radio-iodinated nanobots for radionuclide therapy resulted in a tumour size reduction of about 90%, positioning nanobots as efficient delivery nanosystems for bladder cancer therapy.

Genomic analysis of Mycobacterium brumae sustains its nonpathogenic and immunogenic phenotype

Mycobacterium brumae is a rapid-growing, non-pathogenic Mycobacterium species, originally isolated from environmental and human samples in Barcelona, Spain. Mycobacterium brumae is not pathogenic and it's in vitro phenotype and immunogenic properties have been well characterized. However, the knowledge of its underlying genetic composition is still incomplete. In this study, we first describe the 4 Mb genome of the M. brumae type strain ATCC 51384T assembling PacBio reads, and second, we assess the low intraspecies variability by comparing the type strain with Illumina reads from three additional strains. Mycobacterium brumae genome is composed of a circular chromosome with a high GC content of 69.2% and containing 3,791 CDSs, 97 pseudogenes, one prophage and no CRISPR loci. Mycobacterium brumae has shown no pathogenic potential in in vivo experiments, and our genomic analysis confirms its phylogenetic position with other non-pathogenic and rapid growing mycobacteria. Accordingly, we determined the absence of virulence-related genes, such as ESX-1 locus and most PE/PPE genes, among others. Although the immunogenic potential of M. brumae was proved to be as high as Mycobacterium bovis BCG, the only mycobacteria licensed to treat cancer, the genomic content of M. tuberculosis T cell and B cell antigens in M. brumae genome is considerably lower than those antigens present in M. bovis BCG genome. Overall, this work provides relevant genomic data on one of the species of the mycobacterial genus with high therapeutic potential.

Effects of Mycobacterium bovis Calmette et Guérin (BCG) in oncotherapy: Bladder cancer and beyond

The Mycobacterium bovis Bacillus Calmette et Guérin (BCG) vaccine was generated in 1921 with the efforts of a team of investigators, Albert Calmette and Camille Guérin, dedicated to the determination to develop a vaccine against active tuberculosis (TB) disease. Since then, BCG vaccination is used globally for protection against childhood and disseminated TB; however, its efficacy at protecting against pulmonary TB in adult and aging populations is highly variable. Due to the BCG generated immunity, this vaccine later proved to have an antitumor activity; though the standing mechanisms behind are still unclear. Recent studies indicate that both innate and adaptive cell responses may play an important role in BCG eradication and prevention of bladder cancer. Thus, cells such as natural killer (NK) cells, macrophages, dendritic cells, neutrophils but also MHC-restricted CD4 and CD8 T cells and γδ T cells may play an important role and can be one the main effectors in BCG therapy. Here, we discuss the role of BCG therapy in bladder cancer and other cancers, including current strategies and their impact on the generation and sustainability of protective antitumor immunity against bladder cancer.

Easily applicable modifications to electroporation conditions improve the transformation efficiency rates for rough morphotypes of fast-growing mycobacteria

Electroporation is the most widely used and efficient method to transform mycobacteria. Through this technique, fast- and slow-growing mycobacteria with smooth and rough morphotypes have been successfully transformed. However, transformation efficiencies differ widely between species and strains. In this study, the smooth and rough morphotypes of Mycobacteroides abscessus and Mycolicibacterium brumae were used to improve current electroporation procedures for fast-growing rough mycobacteria. The focus was on minimizing three well-known and challenging limitations: the mycobacterial restriction-modification systems, which degrade foreign DNA; clump formation of electrocompetent cells before electroporation; and electrical discharges during pulse delivery, which were reduced by using salt-free DNA solution. Herein, different strategies are presented that successfully address these three limitations and clearly improve the electroporation efficiencies over the current procedures. The results demonstrated that combining the developed strategies during electroporation is highly recommended for the transformation of fast-growing rough mycobacteria.

Novel anticancer therapy in BCG unresponsive non-muscle-invasive bladder cancer

INTRODUCTION

Many patients with non-muscle-invasive bladder cancer (NMIBC) failed intravesical BCG therapy. Currently, radical cystectomy is the recommended standard of care for those patients. There is unfortunately no effective other second-line therapy recommended.

AREAS COVERED

In this review, we present the topics of BCG unresponsive NMIBC; definition, prognosis, and further treatment options: immunotherapy, intravesical chemotherapy, gene therapy, and targeted individualized therapy.

EXPERT OPINION

There are major challenges of the management of NMIBC who failed BCG therapy as many patients refuse or are unfit for radical cystectomy. Multiple new modalities currently under investigation in ongoing clinical trials to better treat this category of patients. Immunotherapy, especially PD-1/PD-L1 inhibitors, offers exciting and potentially effective strategies for the treatment of BCG unresponsive NMIBC. As the data expands, it is sure that soon there will be established new guidelines for NMIBC.

Mycobacteria-Based Vaccines as Immunotherapy for Non-urological Cancers

The arsenal against different types of cancers has increased impressively in the last decade. The detailed knowledge of the tumor microenvironment enables it to be manipulated in order to help the immune system fight against tumor cells by using specific checkpoint inhibitors, cell-based treatments, targeted antibodies, and immune stimulants. In fact, it is widely known that the first immunotherapeutic tools as immune stimulants for cancer treatment were bacteria and still are; specifically, the use of Mycobacterium bovis bacillus Calmette-Guérin (BCG) continues to be the treatment of choice for preventing cancer recurrence and progression in non-invasive bladder cancer. BCG and also other mycobacteria or their components are currently under study for the immunotherapeutic treatment of different malignancies. This review focuses on the preclinical and clinical assays using mycobacteria to treat non-urological cancers, providing a wide knowledge of the beneficial applications of these microorganisms to manipulate the tumor microenvironment aiming at tumor clearance.

Each Mycobacterium Requires a Specific Culture Medium Composition for Triggering an Optimized Immunomodulatory and Antitumoral Effect

Mycobacterium bovis bacillus Calmette-Guérin (BCG) remains the first treatment option for non-muscle-invasive bladder cancer (BC) patients. In research laboratories, M. bovis BCG is mainly grown in commercially available media supplemented with animal-derived agents that favor its growth, while biomass production for patient treatment is performed in Sauton medium which lacks animal-derived components. However, there is not a standardized formulation of Sauton medium, which could affect mycobacterial characteristics. Here, the impact of culture composition on the immunomodulatory and antitumor capacity of M. bovis BCG and Mycolicibacterium brumae, recently described as efficacious for BC treatment, has been addressed. Both mycobacteria grown in Middlebrook and different Sauton formulations, differing in the source of nitrogen and amount of carbon source, were studied. Our results indicate the relevance of culture medium composition on the antitumor effect triggered by mycobacteria, indicating that the most productive culture medium is not necessarily the formulation that provides the most favorable immunomodulatory profile and the highest capacity to inhibit BC cell growth. Strikingly, each mycobacterial species requires a specific culture medium composition to provide the best profile as an immunotherapeutic agent for BC treatment. Our results highlight the relevance of meticulousness in mycobacteria production, providing insight into the application of these bacteria in BC research.

Mycolicibacterium brumae Is a Safe and Non-Toxic Immunomodulatory Agent for Cancer Treatment

Intravesical Mycobacterium bovis Bacillus Calmette-Guérin (BCG) immunotherapy remains the gold-standard treatment for non-muscle-invasive bladder cancer patients, even though half of the patients develop adverse events to this therapy. On exploring BCG-alternative therapies, Mycolicibacterium brumae, a nontuberculous mycobacterium, has shown outstanding anti-tumor and immunomodulatory capabilities. As no infections due to M. brumae in humans, animals, or plants have been described, the safety and/or toxicity of this mycobacterium have not been previously addressed. In the present study, an analysis was made of M. brumae- and BCG-intravenously-infected severe combined immunodeficient (SCID) mice, M. brumae-intravesically-treated BALB/c mice, and intrahemacoelic-infected-Galleria mellonella larvae. Organs from infected mice and the hemolymph from larvae were processed to count bacterial burden. Blood samples from mice were also taken, and a wide range of hematological and biochemical parameters were analyzed. Finally, histopathological alterations in mouse tissues were evaluated. Our results demonstrate the safety and non-toxic profile of M. brumae. Differences were observed in the biochemical, hematological and histopathological analysis between M. brumae and BCG-infected mice, as well as survival curves rates and colony forming units (CFU) counts in both animal models. M. brumae constitutes a safe therapeutic biological agent, overcoming the safety and toxicity disadvantages presented by BCG in both mice and G. mellonella animal models.

Bacillus Calmette-Guérin (BCG) Therapy for Bladder Cancer: An Update

Physicians treating patients affected by nonmuscle-invasive bladder cancer (NMIBC) have been in shock during the last six years since manufacturing restrictions on the production of the first-option medicine, Mycobacterium bovis Bacillus Calmette-Guérin (BCG), have resulted in worldwide shortages. This shortage of BCG has led to a rethinking of the established treatment guidelines for the rationing of the administration of BCG. Some possible schedule modifications consist of a decrease in the length of maintenance treatment, a reduction in the dose of BCG in intravesical instillations or the use of different BCG substrains. All these strategies have been considered valuable in times of BCG shortage. In addition, the lack of availability of BCG has also led to the general recognition of the need to find new treatment options for these patients so that they are not dependent on a single treatment. Few alternatives are committed to definitively replacing BCG intravesical instillations, but several options are being evaluated to improve its efficacy or to combine it with other chemotherapeutic or immunotherapeutic options that can also improve its effect. In this article, we review the current state of the treatment with BCG in terms of all of the aforementioned aspects.

Intravesical Mycobacterium brumae triggers both local and systemic immunotherapeutic responses against bladder cancer in mice

The standard treatment for high-risk non-muscle invasive bladder cancer (BC) is the intravesical administration of live Mycobacterium bovis BCG. Previous studies suggest improving this therapy by implementing non-pathogenic mycobacteria, such as Mycobacterium brumae, and/or different vehicles for mycobacteria delivery, such as an olive oil (OO)-in-water emulsion. While it has been established that BCG treatment activates the immune system, the immune effects of altering the mycobacterium and/or the preparation remain unknown. In an orthotopic murine BC model, local immune responses were assessed by measuring immune cells into the bladder and macromolecules in the urine by flow cytometry and multiplexing, respectively. Systemic immune responses were analyzed by quantifying sera anti-mycobacteria antibody levels and recall responses of ex vivo splenocytes cultured with mycobacteria antigens. In both BCG- and M. brumae-treated mice, T, NK, and NKT cell infiltration in the bladder was significantly increased. Notably, T cell infiltration was enhanced in OO-in-water emulsified mycobacteria-treated mice, and urine IL-6 and KC concentrations were elevated. Furthermore, mycobacteria treatment augmented IgG antibody production and splenocyte proliferation, especially in mice receiving OO-in-water emulsified mycobacteria. Our data demonstrate that intravesical mycobacterial treatment triggers local and systemic immune responses, which are most significant when OO-in-water emulsified mycobacteria are used.