Intravesical Ty21a Vaccine Promotes Dendritic Cells and T Cell-Mediated Tumor Regression in the MB49 Bladder Cancer Model

Genetic engineering of Salmonella spp. for novel vaccine strategies and therapeutics

Salmonella enterica is a diverse species that infects both humans and animals. S. enterica subspecies enterica consists of more than 1,500 serovars. Unlike typhoidal Salmonella serovars which are human host-restricted, non-typhoidal Salmonella (NTS) serovars are associated with foodborne illnesses worldwide and are transmitted via the food chain. Additionally, NTS serovars can cause disease in livestock animals causing significant economic losses. Salmonella is a well-studied model organism that is easy to manipulate and evaluate in animal models of infection. Advances in genetic engineering approaches in recent years have led to the development of Salmonella vaccines for both humans and animals. In this review, we focus on current progress of recombinant live-attenuated Salmonella vaccines, their use as a source of antigens for parenteral vaccines, their use as live-vector vaccines to deliver foreign antigens, and their use as therapeutic cancer vaccines in humans. We also describe development of live-attenuated Salmonella vaccines and live-vector vaccines for use in animals.

The quantity, function and anti-tumor effect of Mucosal associated invariant T cells in patients with bladder cancer

BACKGROUND

Bladder cancer (BC), a prevalent malignancy in the urinary system, often poses challenges for effective treatment. Immunotherapy, harnessing the immune system, has exhibited promise in early-stage clinical trials. Mucosal associated invariant T (MAIT) cells, a subset of immune cells implicated in various diseases, including certain cancer, have yet to be explored in BC patients. We aimed to investigate the quantity, function, and anti-tumor effects of MAIT cells in BC patients.

METHODS

A total of 75 newly diagnosed BC patients and 183 healthy volunteers were included. Blood samples were collected and analyzed to evaluate the quantity and function of MAIT cells. Surgical resection provided BC tissues for further analysis, and the clinical features of BC tumors were collected and their relationship with MAIT cells was explored.

RESULTS

MAIT cells were identified in both healthy individuals and BC patients. The proportion of MAIT cells in the peripheral blood of BC patients did not significantly differ from that of healthy controls. However, the study revealed a correlation between the proportion of IFN-γ producing MAIT cells and tumor number and invasion in BC patients. Furthermore, MAIT cells exhibited cytotoxic effects on BC cells in vitro and in vivo.

CONCLUSIONS

This study sheds light on the role of MAIT cells in BC. While the quantity of MAIT cells showed no significant change in BC patients, their functional attributes and association with tumor characteristics suggest their potential as an immunotherapy target in BC treatment.

Type 2 innate lymphoid cells are not involved in mouse bladder tumor development

Therapies for bladder cancer patients are limited by side effects and failures, highlighting the need for novel targets to improve disease management. Given the emerging evidence highlighting the key role of innate lymphoid cell subsets, especially type 2 innate lymphoid cells (ILC2s), in shaping the tumor microenvironment and immune responses, we investigated the contribution of ILC2s in bladder tumor development. Using the orthotopic murine MB49 bladder tumor model, we found a strong enrichment of ILC2s in the bladder under steady-state conditions, comparable to that in the lung. However, as tumors grew, we observed an increase in ILC1s but no changes in ILC2s. Targeting ILC2s by blocking IL-4/IL-13 signaling pathways, IL-5, or IL-33 receptor, or using IL-33-deficient or ILC2-deficient mice, did not affect mice survival following bladder tumor implantation. Overall, these results suggest that ILC2s do not contribute significantly to bladder tumor development, yet further investigations are required to confirm these results in bladder cancer patients.

Co-delivery of oxaliplatin prodrug liposomes with Bacillus Calmette-Guérin for chemo-immunotherapy of orthotopic bladder cancer

To reduce recurrence rate after transurethral resection of bladder tumor, long-term intravesical instillations of Bacillus Calmette-Guérin (BCG) and/or chemotherapeutic drugs is the standard treatment for non-muscle invasive bladder carcinoma. However, the main challenges of intravesical therapy, such as short retention time and poor permeability of drugs in the bladder, often require frequent and high-dose administrations, leading to significant adverse effects and financial burden for patients. Aiming at addressing these challenges, we developed a novel approach, in which the cell-penetrating peptide modified oxaliplatin prodrug liposomes and a low-dose BCG were co-delivered via a viscous chitosan solution (LRO-BCG/CS). LRO-BCG/CS addressed these challenges by significantly improving the retention capability and permeability of chemotherapy agents across the bladder wall. Then, oxaliplatin triggered the immunogenic cell death, and the combination of BCG simultaneously further activated the systemic anti-tumor immune response in the MB49 orthotopic bladder tumor model. As a result, LRO-BCG/CS demonstrated superior anti-tumor efficacy and prolonged the survival time of tumor-bearing mice significantly, even at relatively low doses of oxaliplatin and BCG. Importantly, this combinational chemo-immunotherapy showed negligible side effects, offering a promising and well-tolerated therapeutic strategy for bladder cancer patients.

Intravesical Ty21a treatment of non-muscle invasive bladder cancer induces immune responses that correlate with safety and may be associated to therapy potential

BACKGROUND

Standard of care treatment of non-muscle invasive bladder cancer (NMIBC) with intravesical Bacillus Calmette Guérin (BCG) is associated with side effects, disease recurrence/progression and supply shortages. We recently showed in a phase I trial (NCT03421236) that intravesical instillation in patients with NMIBC with the maximal tolerated dose of Ty21a/Vivotif, the oral vaccine against typhoid fever, might have a better safety profile. In the present report, we assessed the immunogenicity of intravesical Ty21a in patients of the clinical trial that had received the maximal tolerated dose and compared it with data obtained in patients that had received standard BCG.

METHODS

Urinary cytokines and immune cells of patients with NMIBC treated with intravesical instillations of Ty21a (n=13, groups A and F in NCT03421236) or with standard BCG in a concomitant observational study (n=12, UROV1) were determined by Luminex and flow cytometry, respectively. Serum anti-lipopolysaccharide Typhi antibodies and circulating Ty21a-specific T-cell responses were also determined in the Ty21a patients. Multiple comparisons of different paired variables were performed with a mixed-effect analysis, followed by Sidak post-test. Single comparisons were performed with a paired or an unpaired Student's t-test.

RESULTS

As compared with BCG, Ty21a induced lower levels of inflammatory urinary cytokines, which correlated to the milder adverse events (AEs) observed in Ty21a patients. However, both Ty21a and BCG induced a Th1 tumor environment. Peripheral Ty21a-specific T-cell responses and/or antibodies were observed in most Ty21a patients, pointing the bladder as an efficient local immune inductive site. Besides, Ty21a-mediated stimulation of unconventional Vδ2 T cells was also observed, which turned out more efficient than BCG. Finally, few Ty21a instillations were sufficient for increasing urinary infiltration of dendritic cells and T cells, which were previously associated with therapeutic efficacy in the orthotopic mouse model of NMIBC.

CONCLUSIONS

Ty21a immunotherapy of patient with NMIBC is promising with fewer inflammatory cytokines and mild AE, but induction of immune responses with possible antitumor potentials. Future phase II clinical trials are necessary to explore possible efficacy of intravesical Ty21a.

The role of microbiota in tumorigenesis, progression and treatment of bladder cancer

For decades, the urinary system was regarded as a sterile environment due to the absence of any bacterial growth in clinical standard urine cultures from healthy individuals. However, a diverse array of microbes colonizes the urinary system in small quantities, exhibiting a variable compositional signature influenced by differences in sex, age, and pathological state. Increasing pieces of evidence suggest microbiota exists in tumor tissue and plays a crucial role in tumor microenvironment based on research in multiple cancer models. Current studies about microbiota and bladder cancer have preliminarily characterized the bladder cancer-related microbiota, but how the microbiota influences the biological behavior of bladder cancer remains unclarified. This review summarizes the characteristics of microbiota in bladder cancer, aims to propose possible mechanisms that microbiota acts in tumorigenesis and progression of bladder cancer based on advances in gut microbiota, and discusses the potential clinical application of microbiota in bladder cancer.

Tumor-Microenvironment Characterization of the MB49 Non-Muscle-Invasive Bladder-Cancer Orthotopic Model towards New Therapeutic Strategies

Bacillus Calmette-Guérin (BCG) instillations for the treatment of non-muscle-invasive bladder cancer patients can result in significant side effects and treatment failure. Immune checkpoint blockade and/or decreasing tumor-infiltrating myeloid suppressor cells may be alternative or complementary treatments. Here, we have characterized immune cell infiltration and chemoattractant molecules in mouse orthotopic MB49 bladder tumors. Our data show a 100-fold increase in CD45⁺ immune cells from day 5 to day 9 tumors including T cells and mainly myeloid cells. Both monocytic myeloid-derived suppressor-cells (M-MDSC) and polymorphonuclear (PMN)-MDSC were strongly increased in day 9 tumors, with PMN-MDSC representing ca. 70% of the myeloid cells in day 12 tumors, while tumor associated macrophages (TAM) were only modestly increased. The kinetic of PD-L1 tumor expression correlated with published data from patients with PD-L1 expressing bladder tumors and with efficacy of anti-PD-1 treatment, further validating the orthotopic MB49 bladder-tumor model as suitable for designing novel therapeutic strategies. Comparison of chemoattractants expression during MB49 bladder tumors grow highlighted CCL8 and CCL12 (CCR2-ligands), CCL9 and CCL6 (CCR-1-ligands), CXCL2 and CXCL5 (CXCR2-ligands), CXCL12 (CXCR4-ligand) and antagonist of C5/C5a as potential targets to decrease myeloid suppressive cells. Data obtained with a single CCR2 inhibitor however showed that the complex chemokine crosstalk would require targeting multiple chemokines for anti-tumor efficacy.

Intravesical Ty21a Treatment of Non-muscle-invasive Bladder Cancer Shows a Good Safety Profile

Standard-of-care immunotherapy for non–muscle-invasive bladder cancer (NMIBC) with intravesical Bacillus Calmettte-Guérin (BCG) is associated with adverse events (AEs), disease recurrence/progression, and supply shortages. Preclinical data have shown that intravesical instillation of Ty21a/Vivotif, the oral vaccine against typhoid fever, may be an effective and safer alternative to BCG. We assessed the safety of intravesical Ty21a in NMIBC. For ethical reasons, patients with low- or intermediate-risk NMIBC not requiring BCG immunotherapy were enrolled. To determine the maximum tolerated dose, escalating doses of Ty21a/Vivotif were intravesically instilled in three patients once a week for 4 wk in phase 1a. In phase 1b, ten patients received the selected dose (1 × 10⁸ CFU) once a week for 6 wk, as for standard BCG therapy. At this dose, all patients completed their treatment. Most patients experienced minor systemic AEs, while half reported mild local bladder AEs. AEs only occurred after one or two instillations for 40% of the patients. Ty21a bacteria were only recovered in three out of 72 urinary samples at 1 wk after instillation. Intravesical Ty21a might be well tolerated with no cumulative side effects, no fever >39 °C, and lower risk of bacterial persistence than with BCG. Ty21a treatment thus warrants clinical trials to explore its safety and antitumor efficacy in high-risk NMIBC. This trial is registered on ClinicalTrials.gov as NCT03421236.

Patient summary

We examined the safety of a new intra-bladder immunotherapy for non–muscle-invasive bladder cancer as an alternative to the standard BCG treatment. Our data show that the Ty21a vaccine might be well tolerated. Further studies are needed to determine the safety and antitumor efficacy of this treatment.

Recombinant Attenuated Salmonella enterica as a Delivery System of Heterologous Molecules in Cancer Therapy

Simple Summary

Cancer is among the main causes of death of millions of individuals worldwide. Although survival has improved with conventional treatments, the appearance of resistant cancer cells leads to patient relapses. It is, therefore, necessary to find new antitumor therapies that can completely eradicate transformed cells. Bacteria-based tumor therapy represents a promising alternative treatment, particularly the use of live-attenuated Salmonella enterica, with its potential use as a delivery system of antitumor heterologous molecules such as tumor-associated antigens, cytotoxic molecules, immunomodulatory molecules, pro-apoptotic proteins, nucleic acids, and nanoparticles. In this review, we present the state of the art of current preclinical and clinical research on the use of Salmonella enterica as a potential therapeutic ally in the war against cancer.

Abstract

Over a century ago, bacterial extracts were found to be useful in cancer therapy, but this treatment modality was obviated for decades. Currently, in spite of the development and advances in chemotherapies and radiotherapy, failure of these conventional treatments still represents a major issue in the complete eradication of tumor cells and has led to renewed approaches with bacteria-based tumor therapy as an alternative treatment. In this context, live-attenuated bacteria, particularly Salmonella enterica, have demonstrated tumor selectivity, intrinsic oncolytic activity, and the ability to induce innate or specific antitumor immune responses. Moreover, Salmonella enterica also has strong potential as a delivery system of tumor-associated antigens, cytotoxic molecules, immunomodulatory molecules, pro-apoptotic proteins, and nucleic acids into eukaryotic cells, in a process known as bactofection and antitumor nanoparticles. In this review, we present the state of the art of current preclinical and clinical research on the use of Salmonella enterica as a potential therapeutic ally in the war against cancer.

Novel intravesical bacterial immunotherapy induces rejection of BCG-unresponsive established bladder tumors

Background

Intravesical BCG is the gold-standard therapy for non-muscle invasive bladder cancer (NMIBC); however, it still fails in a significant proportion of patients, so improved treatment options are urgently needed.

Methods

Here, we compared BCG antitumoral efficacy with another live attenuated mycobacteria, MTBVAC, in an orthotopic mouse model of bladder cancer (BC). We aimed to identify both bacterial and host immunological factors to understand the antitumoral mechanisms behind effective bacterial immunotherapy for BC.

Results

We found that the expression of the BCG-absent proteins ESAT6/CFP10 by MTBVAC was determinant in mediating bladder colonization by the bacteria, which correlated with augmented antitumoral efficacy. We further analyzed the mechanism of action of bacterial immunotherapy and found that it critically relied on the adaptive cytotoxic response. MTBVAC enhanced both tumor antigen-specific CD4⁺ and CD8⁺ T-cell responses, in a process dependent on stimulation of type 1 conventional dendritic cells. Importantly, improved intravesical bacterial immunotherapy using MBTVAC induced eradication of fully established bladder tumors, both as a monotherapy and specially in combination with the immune checkpoint inhibitor antiprogrammed cell death ligand 1 (anti PD-L1).

Conclusion

These results contribute to the understanding of the mechanisms behind successful bacterial immunotherapy against BC and characterize a novel therapeutic approach for BCG-unresponsive NMIBC cases.

Emerging treatment landscape of non-muscle invasive bladder cancer

INTRODUCTION

Non-muscle invasive bladder cancer (NMIBC) accounts for 70-75% of all bladder cancers and is a heterogeneous disease characterized by a wide spectrum of recurrences and progression. Adjuvant treatment for intermediate- and high-risk NMIBC is mainly represented by Bacillus Calmette Guerin (BCG). However, 20%-40% of patients develop disease recurrences or persistence following BCG treatment and are classified as "BCG unresponsive' (BCGu), thus representing a therapeutic challenge due to their worse prognosis and unavailability of effective intravesical treatments.

AREAS COVERED

We provide an overview of completed and ongoing clinical trials assessing the role of innovative immunological and target agents in patients with BCGu and BCG naive (BCGn) NMIBCs. New treatment options are emerging, demonstrating promising clinical activity, namely, pembrolizumab, atezolizumab, oportuzumab monatox, nadofaragene firadenovec, and N-803.

EXPERT OPINION

The increasing number of newer therapeutic agents for patients with NMIBC poses challenges regarding the choice of the most suited treatment option for each patient and the best treatment sequence, given their diverse mechanisms of action and varying degrees of activity. Tailored treatment approaches are advocated, based on a deeper comprehension of disease features, available therapies, patient's characteristics, and consequently, on the identification and validation of prognostic and predictive biomarkers.

The inflammatory microenvironment and the urinary microbiome in the initiation and progression of bladder cancer

Accumulating evidence suggests that chronic inflammation may play a critical role in various malignancies, including bladder cancer. This hypothesis stems in part from inflammatory cells observed in the urethral microenvironment. Chronic inflammation may drive neoplastic transformation and the progression of bladder cancer by activating a series of inflammatory molecules and signals. Recently, it has been shown that the microbiome also plays an important role in the development and progression of bladder cancer, which can be mediated through the stimulation of chronic inflammation. In effect, the urinary microbiome can play a role in establishing the inflammatory urethral microenvironment that may facilitate the development and progression of bladder cancer. In other words, chronic inflammation caused by the urinary microbiome may promote the initiation and progression of bladder cancer. Here, we provide a detailed and comprehensive account of the link between chronic inflammation, the microbiome and bladder cancer. Finally, we highlight that targeting the urinary microbiome might enable the development of strategies for bladder cancer prevention and personalized treatment.

Intravesical Pseudomonas aeruginosa mannose-sensitive Hemagglutinin vaccine triggers a tumor-preventing immune environment in an orthotopic mouse bladder cancer model

Bacillus Calmette-Guerin (BCG) immunotherapy can prevent recurrence and progression in selected patients with non-muscle-invasive bladder cancer (NMIBC); however, significant adverse events and treatment failure suggest the need for alternative agents. A commercial anti-infection vaccine comprises a genetically engineered heat-killed Pseudomonas aeruginosa (PA) expressing many mannose-sensitive hemagglutination (MSHA) fimbriae, termed PA-MSHA, which could be a candidate for bladder cancer intravesical therapy. In an immunocompetent orthotopic MB49 bladder cancer model, we characterized the antitumor effects and mechanisms of PA-MSHA compared with those of BCG. Three weekly intravesical PA-MSHA or BCG treatments reduced tumor involvement; however, only PA-MSHA prolonged survival against MB49 implantation significantly. In non-tumor-bearing mice after treatment, flow-cytometry analysis showed PA-MSHA and BCG induced an increased CD4/CD8 ratio, the levels of effector memory T cell phenotypes (CD44, CXCR-3, and IFN-γ), and the proportion of CD11b⁺Ly6G^-Ly6C^-IA/IE⁺ mature macrophages, but a decrease in the proportion of CD11b⁺Ly6G^-Ly6C⁺IA/IE^- monocytic myeloid-derived suppressor cells (Mo-MDSCs) and the expression of suppressive molecules on immune cells (PD-L1, PD-1, TIM-3, and LAG-3). Notably, PA-MSHA, but not BCG, significantly reduced PD-1 and TIM-3 expression on CD4⁺ T cells, which might account for the better effects of PA-MSHA than BCG. However, in tumor-bearing mice after treatment, the increased proportion of Mo-MDSCs and high expression of PD-L1 might be involved in treatment failure. Thus, modulating the balance among adaptive and innate immune responses was identified as a key process underlying PA-MSHA-mediated treatment efficacy. The results demonstrated mechanisms underlying intravesical PA-MSHA therapy, pointing at its potential as an alternative effective treatment for NMIBC.

Inhibition of the BTK-IDO-mTOR axis promotes differentiation of monocyte-lineage dendritic cells and enhances anti-tumor T cell immunity

Monocytic-lineage inflammatory Ly6c+CD103+ dendritic cells (DCs) promote antitumor immunity, but these DCs are infrequent in tumors, even upon chemotherapy. Here, we examined how targeting pathways that inhibit the differentiation of inflammatory myeloid cells affect antitumor immunity. Pharmacologic inhibition of Bruton's tyrosine kinase (BTK) and the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) or deletion of Btk or Ido1 allowed robust differentiation of inflammatory Ly6c+CD103+ DCs during chemotherapy, promoting antitumor T cell responses and inhibiting tumor growth. Immature Ly6c+c-kit+ precursor cells had epigenetic profiles similar to conventional DC precursors; deletion of Btk or Ido1 promoted differentiation of these cells. Mechanistically, a BTK-IDO axis inhibited a tryptophan-sensitive differentiation pathway driven by GATOR2 and mTORC1, and disruption of the GATOR2 in monocyte-lineage precursors prevented differentiation into inflammatory DCs in vivo. IDO-expressing DCs and monocytic cells were present across a range of human tumors. Thus, a BTK-IDO axis represses differentiation of inflammatory DCs during chemotherapy, with implications for targeted therapies.

Local induction of bladder Th1 responses to combat urinary tract infections

Given the high frequency of urinary tract infections (UTIs) and their recurrence, there is keen interest in developing effective UTI vaccines. Currently, most vaccine studies, including those in humans, involve parenteral vaccination aimed at evoking and sustaining elevated levels of systemic antibody directed at the uropathogens. In view of recent reports of aberrant Th2-biased bladder immune responses to infection, we hypothesized that immunizing mice intravesically with antigens from uropathogenic Escherichia coli (UPEC) combined with a Th1-skewing adjuvant could correct this defect and promote protection against UTIs. Here we report that compared with mice immunized subcutaneously with this vaccine combination, intravesically immunized mice were markedly more protected from UTIs because of their distinctive ability to recruit Th1 cells into the bladder. This mode of vaccination was effective even in mice that experienced multiple UTIs and displayed pronounced aberrant bladder immune responses. Thus, intravesical vaccination with one or more UPEC antigens to induce bladder Th1 responses represents a superior strategy to combat UTIs, especially in UTI-prone subjects.

Non-muscle-invasive bladder cancer: An overview of potential new treatment options

AIM

This review article summarizes the current clinical practice guidelines around disease definitions and risk stratifications, and the treatment of non-muscle-invasive bladder cancer (NMIBC). Recently completed and ongoing clinical trials of novel and investigational therapies in Bacillus Calmette-Guérin (BCG)-naïve, BCG-recurrent, and BCG-unresponsive patient populations are also described, e.g., those involving immune checkpoint inhibitors, targeted therapies, other chemotherapy regimens, vaccines, and viral- or bacterial-based treatments. Finally, a brief overview of enhanced cystoscopy and drug delivery systems for the diagnosis and treatment of NMIBC is provided.

BACKGROUND

A global shortage of access to BCG is affecting the management of BCG-naïve and BCG-recurrent/unresponsive NMIBC; hence, there is an urgent need to assist patients and urologists to enhance the treatment of this disease.

METHODS

Searches of ClinicalTrials.gov, PubMed, and Google Scholar were conducted. Published guidance and conference proceedings from major congresses were reviewed.

CONCLUSION

Treatment strategies for NMIBC are generally consistent across guidelines. Several novel therapies have demonstrated promising antitumor activity in clinical trials, including in high-risk or BCG-unresponsive disease. The detection, diagnosis, surveillance, and treatment of NMIBC have also been improved through enhanced disease detection.

Repurposing Infectious Diseases Vaccines Against Cancer

Vaccines used to prevent infections have long been known to stimulate immune responses to cancer as illustrated by the approval of the Bacillus Calmette-Guérin (BCG) vaccine to treat bladder cancer since the 1970s. The recent approval of immunotherapies has rejuvenated this research area with reports of anti-tumor responses with existing infectious diseases vaccines used as such, either alone or in combination with immune checkpoint inhibitors. Here, we have reviewed and summarized research activities using approved vaccines to treat cancer. Data supporting a cancer therapeutic use was found for 16 vaccines. For 10 (BCG, diphtheria, tetanus, human papillomavirus, influenza, measles, pneumococcus, smallpox, typhoid and varicella-zoster), clinical trials have been conducted or are ongoing. Within the remaining 6, preclinical evidence supports further evaluation of the rotavirus, yellow fever and pertussis vaccine in carefully designed clinical trials. The mechanistic evidence for the cholera vaccine, combined with the observational data in colorectal cancer, is also supportive of clinical translation. There is limited data for the hepatitis B and mumps vaccine (without measles vaccine). Four findings are worth highlighting: the superiority of intravesical typhoid vaccine instillations over BCG in a preclinical bladder cancer model, which is now the subject of a phase I trial; the perioperative use of the influenza vaccine to limit and prevent the natural killer cell dysfunction induced by cancer surgery; objective responses following intratumoral injections of measles vaccine in cutaneous T-cell lymphoma; objective responses induced by human papillomavirus vaccine in cutaneous squamous cell carcinoma. All vaccines are intended to induce or improve an anti-tumor (immune) response. In addition to the biological and immunological mechanisms that vary between vaccines, the mode of administration and sequence with other (immuno-)therapies warrant more attention in future research.

Surface Labeling with Adhesion Protein FimH Improves Binding of Immunotherapeutic Agent Salmonella Ty21a to the Bladder Epithelium

BACKGROUND

Bladder cancer is the ninth most common cancer in men. 70% of these tumors are classified as non-muscle invasive bladder cancer and those patients receive 6 intravesical instillations with Mycobacterium bovis BCG after transurethral resection. However, 30% of patients show recurrences after treatment and experience severe side effects that often lead to therapy discontinuation. Recently, another vaccine strain, Salmonella enterica typhi Ty21a, demonstrated promising antitumor activity in vivo. Here we focus on increasing bacterial retention in the bladder in order to reduce the number of instillations required and improve antitumor activity.

OBJECTIVE

To increase the binding of Ty21a to the bladder wall by surface labeling of the bacteria with adhesion protein FimH and to study its effect in a bladder cancer mouse model.

METHODS

Binding of Ty21a with surface-labeled FimH to the bladder wall was analyzed in vitro and in vivo. The antitumor effect of a single instillation of Ty21a+FimH in treatment was determined in a survival experiment.

RESULTS

FimH-labeled Ty21a showed significant (p < 0.0001) improved binding to mouse and human cell lines in vitro. Furthermore, FimH labeled bacteria showed ∼5x more binding to the bladder than controls in vivo. Enhanced binding to the bladder via FimH labeling induced a modest improvement in median but not in overall mice survival.

CONCLUSIONS

FimH labeling of Ty21a significantly improved binding to bladder tumor cells in vitro and the bladder wall in vivo. The improved binding leads to a modest increase in median survival in a single bladder cancer mouse study.

The Roles of T cells in Bladder Pathologies

T lymphocytes play important roles in the skin and mucosal surfaces such as the gut and lung. Until recently the contributions of T cells to mammalian bladder immunity were largely unknown. With newer techniques, including single-cell RNA sequencing and reporter mice, an understanding is emerging of T cell roles in bladder diseases (bacterial infections, bladder cancer, chronic inflammation). In these pathologies, many bladder T cell responses can be harmful to the host through suboptimal clearance of bacteria or cancer cells, or by modulating autoinflammation. Recent findings suggest that T cell behavior might be influenced by resident T cell interactions with the bladder microbiota and other immunostimulants. Thus, regulating bladder T cell functions could emerge as a putative immunotherapy to treat some bladder diseases.

Bacillus Calmette-Guerin (BCG): Its fight against pathogens and cancer

Bacillus Calmette-Guerin (BCG) is the only FDA approved first line therapy for patients with nonmuscle invasive bladder cancer. Since the turn of the 20th century BCG has been used as a vaccine for protection against Mycobacterium tuberculosis (Mtb) and has also been found to have protection against nontuberculosis related pathogens. Recently the role of "trained immunity" has been identified as a possible mechanism for BCG vaccine-mediated immunity to Mtb. Similarly, BCG has been used as an immunotherapy for bladder cancer for more than 40 years, and the underlying mechanisms for BCG-mediated anti-tumor activity is poorly characterized. Several studies have shown that multiple immune pathways contribute to the immune response, and efficacy of intravesicle BCG as a cancer therapy. It is vital that we integrate our understanding of BCG as a vaccine and as a cancer therapeutic to facilitate design of future studies in order to maximize the immunotherapeutic potential of BCG. In this review we will outline the role of BCG as a vaccine, the known immune pathways that are activated by intravesical BCG and outline a potential clinical study integrating BCG vaccination prior to intravesicle instillation of BCG.

ATM Mutations Benefit Bladder Cancer Patients Treated With Immune Checkpoint Inhibitors by Acting on the Tumor Immune Microenvironment

Immune checkpoint inhibitors (ICIs) have shown promising results in bladder cancer (BC). However, only some patients respond to ICIs. DNA repair defects (DDR) play an important role in the therapeutic response of bladder cancer. Therefore, we aimed to elucidate the association between ICIs in bladder cancer and ataxia telangiectasia mutated (ATM), a core component of the DNA repair system. From a collected immunotherapy cohort (n = 210) and The Cancer Genome Atlas (TCGA)-Bladder cancer cohort, which were both retrieved from publicly available resources, we performed a series of analyses to evaluate the prognostic value and potential mechanism of ATM in bladder cancer immunotherapy. We found that ATM-mutant (ATM-MT) bladder cancer patients derived greater benefit from ICIs [overall survival (OS), hazard ratio (HR) = 0.28, [95% confidence interval (CI), 0.16 to 0.51], P = 0.007] and showed a higher mutation load (P < 0.05) and immunogenicity (P < 0.05) than ATM-wild-type (ATM-WT) patients. The immune inflammatory response to antigenic stimulation, the regulation of the IFN pathway and the macrophage activation pathway were significantly enriched in the ATM-MT group (NES > 1, P < 0.05), while insulin-like growth factor receptor signaling pathways and vasculogenesis were significantly downregulated (NES < −1, P < 0.05). ATM mutation significantly upregulated the number of DNA damage repair pathway gene mutations (P < 0.05). ATM mutations resulted in increased bladder cancer sensitivity to 29 drugs (P < 0.05), including cisplatin and BMS-536924, an IGF-1R inhibitor. Our results demonstrate the importance of ATM as a prognostic signature in bladder cancer and reveal that ATM may impact the effects of ICIs by acting on the tumor immune microenvironment.

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.