The role of neutrophils and TNF-related apoptosis-inducing ligand (TRAIL) in bacillus Calmette–Guérin (BCG) immunotherapy for urothelial carcinoma of the bladder

Prognostic role of the neutrophil/lymphocyte ratio in high-risk BCG-naïve non-muscle-invasive bladder cancer treated with intravesical gemcitabine/docetaxel

OBJECTIVES

To investigate the role of pretreatment neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in the prediction of response to sequential intravesical therapy, gemcitabine and docetaxel (Gem/Doce), given to patients with bacille Calmette-Guérin (BCG)- naïve high-risk non-muscle-invasive bladder cancer (NMIBC).

PATIENTS AND METHODS

A retrospective analysis was conducted on 115 patients who received intravesical Gem/Doce for high-risk NMIBC between January 2011 and December 2021. Data were computed as the median (interquartile range [IQR]) or mean (standard deviation [sd]). Cox regression analysis was performed to determine if neutrophilia, NLR, platelet counts, and PLR before instillation therapy were predictive of recurrence-free survival (RFS) and overall survival (OS). Predictive performance was estimated using Uno's C-statistic.

RESULTS

The median (IQR) follow-up for the overall cohort was 23 (13-36) months. The mean (sd) values for NLR, PLR and platelet counts were 3.4 (2.3), 142.2 (85.5), and 225.2 (75.1) × 109/L, respectively. NLR was associated with RFS, with a hazard ratio of 1.32 (95% confidence interval CI 1.19-1.46). Concordance analysis showed that NLR had a good ability to predict RFS (C-index: 0.7, P < 0.01). The PLR and platelet count were not associated with RFS and did not predict recurrence. In terms of OS, none of these cellular inflammatory markers showed any prediction value.

CONCLUSION

Pre-treatment NLR provides some predictive accuracy for RFS in high-risk BCG-naïve patients receiving Gem/Doce. Further prospective trials are needed to validate this finding.

Radiation-induced tumor immune microenvironments and potential targets for combination therapy

As one of the four major means of cancer treatment including surgery, radiotherapy (RT), chemotherapy, immunotherapy, RT can be applied to various cancers as both a radical cancer treatment and an adjuvant treatment before or after surgery. Although RT is an important modality for cancer treatment, the consequential changes caused by RT in the tumor microenvironment (TME) have not yet been fully elucidated. RT-induced damage to cancer cells leads to different outcomes, such as survival, senescence, or death. During RT, alterations in signaling pathways result in changes in the local immune microenvironment. However, some immune cells are immunosuppressive or transform into immunosuppressive phenotypes under specific conditions, leading to the development of radioresistance. Patients who are radioresistant respond poorly to RT and may experience cancer progression. Given that the emergence of radioresistance is inevitable, new radiosensitization treatments are urgently needed. In this review, we discuss the changes in irradiated cancer cells and immune cells in the TME under different RT regimens and describe existing and potential molecules that could be targeted to improve the therapeutic effects of RT. Overall, this review highlights the possibilities of synergistic therapy by building on existing research.

Polymorphonuclear Neutrophils and Tumors: Friend or Foe?

Tumor microenvironment (TME) is a dynamic network that apart from tumor cells includes also cells of the immune system, e.g., neutrophils, which are recruited from blood circulation. In TME, neutrophils are strongly implicated in the direct and indirect interactions with tumor cells or other immune cells, and they play roles in both preventing and/or facilitating tumor progression and metastasis. The dual role of neutrophils is determined by their high plasticity and heterogeneity. Analogous to the macrophages, neutrophils can express antitumoral (N1) and protumoral (N2) phenotypes which differ substantially in morphology and function. N1 phenotype characterizes with a high cytotoxic and proinflammatory activities, while N2 phenotype with immunosuppressive and prometastatic properties. The antitumoral effect of neutrophils includes for example the production of reactive oxygen species or proapoptotic molecules. The protumoral action of neutrophils relies on releasing of proangiogenic and prometastatic mediators, immunosuppressive factors, as well as on direct helping tumor cells in extravasation process. This chapter summarizes the heterogeneity of neutrophils in TME, as well as their dual role on tumor cells.

The inhibitory effect of rBCG on EB virus-positive tumours using an EB virus fusion gene

At present, studies have found that latent Epstein-Barr virus (EBV) infection is associated with a variety of human tumours, and a vaccine is not available in this field. In this research, RT-PCR was used to obtain BZLF1 (immediately expressed early antigen Z) and LMP2 (latent membrane protein 2) cDNA from EBV. A ZLP2 fusion gene containing a linker sequence that encoded the polypeptide (Gly₄Ser)₃ was obtained using the sequence splicing overlap extension method. Then, ZLP2 was inserted into pMV261 cells, and the recombinant plasmid pMV-ZLP2 was transformed into BCG competent cells. After EB virus-positive tumour cell (NPRC18) cancer models were established with C57BL/6 J mice, tumour weight, tumour formation time and mouse survival conditions were analyzed, and flow cytometry was used to analyze the quantities of CD8 + and CD4 + T cells. HE staining was used to detect and analyze lymphocyte infiltration, and statistical analysis was used to analyze the immunological effect of recombinant BCG (rBCG). Compared with the control group, rBCG could significantly prolong the survival time of mice, slow tumour growth and delay tumour formation time. Recombinant BCG exhibits an obvious immune effect in mice and an inhibitory effect on EBV-positive cancer.Key points• AZLP2 fusion gene with BZLF1 and LMP2 of EB virus was constructed.• ZLP2 fusion gene was expressed with rBCG.• rBCG with ZLP2 has an obvious effect on EBV-positive cancer.

Non-Muscular Invasive Bladder Cancer: Re-envisioning Therapeutic Journey from Traditional to Regenerative Interventions

Non-muscular invasive bladder cancer (NMIBC) is one of the most common cancer and major cause of economical and health burden in developed countries. Progression of NMIBC has been characterized as low-grade (Ta) and high grade (carcinoma in situ and T1). The current surgical intervention for NMIBC includes transurethral resection of bladder tumor; however, its recurrence still remains a challenge. The BCG-based immunotherapy is much effective against low-grade NMIBC. BCG increases the influx of T cells at bladder cancer site and inhibits proliferation of bladder cancer cells. The chemotherapy is another traditional approach to address NMIBC by supplementing BCG. Notwithstanding, these current therapeutic measures possess limited efficacy in controlling NMIBC, and do not provide comprehensive long-term relief. Hence, biomaterials and scaffolds seem an effective medium to deliver therapeutic agents for restructuring bladder post-treatment. The regenerative therapies such as stem cells and PRP have also been explored for possible solution to NMIBC. Based on above-mentioned approaches, we have comprehensively analyzed therapeutic journey from traditional to regenerative interventions for the treatment of NMIBC.

Mathematical model of tumor immunotherapy for bladder carcinoma identifies the limitations of the innate immune response

Treatment for non-muscle invasive carcinoma of the bladder represents one of the few examples of successful tumor immunity. Six weekly intravesical instillations of Bacillus Calmette-Guerin (BCG), often followed by maintenance schedule, result in up to 50-70% clinical response. Current models suggest that the mechanism of action involves the non-specific activation of innate effector cells, which may be capable of acting in the absence of an antigen-specific response. For example, recent evidence suggests that BCG-activated neutrophils possess anti-tumor potential. Moreover, weekly BCG treatment results in a prime-boost pattern with massive influx of innate immune cells (107-108 PMN/ml urine). Calibrating in vivo data, we estimate that the number of neutrophil degranulations per instillation is approximately 106-107, more than sufficient to potentially eliminate ~106 residual tumor cells. Furthermore, neutrophils, as well as other innate effector cells are not selective in their targeting-thus surrounding cells may be influenced by degranulation and / or cytokine production. To establish if these observed conditions could account for clinically effective tumor immunity, we built a mathematical model reflecting the early events and tissue conditioning in patients undergoing BCG therapy. The model incorporates key features of tumor growth, BCG instillations and the observed prime / boost pattern of the innate immune response. Model calibration established that each innate effector cell must kill 90-95 bystander cells for achieving the expected 50-70% clinical response. This prediction was evaluated both empirically and experimentally and found to vastly exceed the capacity of the innate immune system. We therefore conclude that the innate immune system alone is unable to eliminate the tumor cells. We infer that other aspects of the immune response (e.g., antigen-specific lymphocytes) decisively contribute to the success of BCG immunotherapy.

Anti-tumor efficacy of plasmid encoding emm55 in a murine melanoma model

Emm55 is a bacterial gene derived from Streptococcus pyogenes (S. pyogenes) that was cloned into a plasmid DNA vaccine (pAc/emm55). In this study, we investigated the anti-tumor efficacy of pAc/emm55 in a B16 murine melanoma model. Intralesional (IL) injections of pAc/emm55 significantly delayed tumor growth compared to the pAc/Empty group. There was a significant increase in the CD8+ T cells infiltrating into the tumors after pAc/emm55 treatment compared to the control group. In addition, we observed that IL injection of pAc/emm55 increased antigen-specific T cell infiltration into tumors. Depletion of CD4+ or CD8+ T cells abrogated the anti-tumor effect of pAc/emm55. Combination treatment of IL injection of pAc/emm55 with anti-PD-1 antibody significantly delayed tumor growth compared to either monotherapy. pAc/emm55 treatment combined with PD-1 blockade enhanced anti-tumor immune response and improved systemic anti-tumor immunity. Together, these strategies may lead to improvements in the treatment of patients with melanoma.

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.

Mechanisms of BCG in the treatment of bladder cancer-current understanding and the prospect

Over 30 years' successful application of Bacillus Calmette Guerin (BCG) to the clinical treatment of bladder cancer has proved it one of the most promising immunotherapies for cancer. However, the applications and achievements have failed to uncover the mechanism of BCG works on bladder cancer fully. Clinically, the administration of BCG on patients results in no effect, or apparent resistance, and even severe adverse reactions, which are inexplicable. At present, the widely confirmed and accepted immunity mechanism of BCG fall in the processes of the absorption after the instillation of BCG, the internalization of BCG, cytokine release induced by a series of signal transduction pathways, and the effect stage of innate and acquired immune responses. Nonetheless, the limited ascertainments of the mechanism of BCG action cannot fully explain the clinical phenomenon caused by BCG. Therefore, the other mechanisms of BCG action have remained the research hotspot aiming to explore more targeted treatments or to initiate new therapeutic methods avoiding harm. By summarizing the recent research achievements of the mechanism of BCG works on bladder cancer, this review aims to provide clues for researchers to quest more valuable ideas.

Text mining in a literature review of urothelial cancer using topic model

Background

Urothelial cancer (UC) includes carcinomas of the bladder, ureters, and renal pelvis. New treatments and biomarkers of UC emerged in this decade. To identify the key information in a vast amount of literature can be challenging. In this study, we use text mining to explore UC publications to identify important information that may lead to new research directions.

Method

We used topic modeling to analyze the titles and abstracts of 29,883 articles of UC from Pubmed, Web of Science, and Embase in Mar 2020. We applied latent Dirichlet allocation modeling to extract 15 topics and conducted trend analysis. Gene ontology term enrichment analysis and Kyoto encyclopedia of genes and genomes pathway analysis were performed to identify UC related pathways.

Results

There was a growing trend regarding UC treatment especially immune checkpoint therapy but not the staging of UC. The risk factors of UC carried in different countries such as cigarette smoking in the United State and aristolochic acid in Taiwan and China. GMCSF, IL-5, Syndecan-1, ErbB receptor, integrin, c-Met, and TRAIL signaling pathways are the most relevant biological pathway associated with UC.

Conclusions

The risk factors of UC may be dependent on the countries and GMCSF, IL-5, Syndecan-1, ErbB receptor, integrin, c-Met, and TRAIL signaling pathways are the most relevant biological pathway associated with UC. These findings may provide further UC research directions.

Two-Faced Roles of Tumor-Associated Neutrophils in Cancer Development and Progression

Neutrophils are the most abundant circulating leukocytes in humans. Neutrophil infiltration into tumor tissues has long been observed but its roles have been ignored due to the presumed short life cycle and metabolic incompetence of neutrophils. Recent advances in neutrophil biology research have revealed that neutrophils have a longer life cycle with a potential to express various bioactive molecules. Clinical studies have simultaneously unraveled an increase in the neutrophil–lymphocyte ratio (NLR), a ratio of absolute neutrophil to absolute lymphocyte numbers in cancer patient peripheral blood and an association of higher NLR with more advanced or aggressive disease. As a consequence, tumor-associated neutrophils (TANs) have emerged as important players in tumor microenvironment. The elucidation of the roles of TANs, however, has been hampered by their multitude of plasticity in terms of phenotypes and functionality. Difficulties are further enhanced by the presence of a related cell population—polymorphonuclear leukocyte (PMN)-myeloid-derived suppressor cells (MDSCs)—and various dissimilar aspects of neutrophil biology between humans and mice. Here, we discuss TAN biology in various tumorigenesis processes, and particularly focus on the context-dependent functional heterogeneity of TANs.

EB virus-positive tumors are inhibited by rBCG expressing hGM-CSF and LMP2A

For the development of safe and effective EBV (Epstein-Barr virus) vaccines, the Ag85A signal peptide from M. tuberculosis H37Rv was used to construct a recombinant secretory BCG (Bacillus Chalmette-Guérin) plasmid. The Ag85A gene, fused to the EBV LMP2A (latent membrane protein) and hGM-CSF (human granulocyte/macrophage colony-stimulating factor) genes, was inserted into the pMV261 vector (secretory BCG plasmid). The expression levels of the hGM-CSF and LMP2A proteins in rBCG (recombinant BCG) were measured by Western blot analysis. Humoral immunity, cellular immunity, and antitumor effects were determined by a series of experiments. The recombinant pMVGCA plasmid effectively expressed GCA (hGM-CSF and LMP2A fusion protein) in BCG after transformation, and the rBCG proteins were recognized by antibodies against hGM-CSF and LMP2A. Six weeks after immunization, the maximum dose of rBCG resulted in antibody titers of 1:19,800 (hGM-CSF antibody) and 1:21,800 (LMP2A antibody). When the effector:target ratio was 40:1, specific lysis was maximal and approximately two times stronger than that in mice immunized with the control. Tumorigenicity was lower in the rBCG treatment group, with a tumor inhibition rate of 0.81 ± 0.09 compared with the control groups. EB virus-positive tumors are inhibited by rBCG expressing an hGM-CSF and LMP2A fusion protein.

Immune Responses in Bladder Cancer-Role of Immune Cell Populations, Prognostic Factors and Therapeutic Implications

Immunosurveillance, which describes the immunologically mediated elimination of transformed cells, has been widely accepted in the context of bladder cancer for many decades with the successful use of Bacillus-Calmette Guerin for superficial bladder cancer since the 1970s. With the emergence of checkpoint inhibitor blockade in the treatment of urothelial cancers, there has been a resurgent interest in the immunology of bladder cancer. The theory of cancer immunoediting proposes that the immune system has both pro-tumorigenic and anti-tumor effects, the balance between the two determining the progression of an individual tumor. However, whilst there is evidence for the action of various immune cell populations in bladder cancer, a cohesive picture of the immune response to bladder cancer and its driving forces are still lacking. Additionally, little is still known about the normal immune landscape of the bladder. Future progress in bladder cancer therapeutic approaches will require a strong foundation in understanding the immunology of this disease. This review considers the evidence for the role of the main immune cell populations, both innate and adaptive, in the immune response to bladder cancer. Recent research and overarching themes in the immune response to bladder cancer are explored. The minimal evidence regarding the normal immune landscape of the human bladder is also summarized to contextualize downstream immune responses. Of specific interest are the innate and myeloid populations, some of which are resident in the human bladder and which have significant effects on downstream adaptive tumor immunity. We discuss factors which restrain the efficacy of populations known to have anti-tumor activity such as cytotoxic T cells, including the constraints on checkpoint blockade. Additionally, the effects on the immune response of tumor intrinsic factors such as the genomic subtype of bladder cancer and the effect of common therapies such as chemotherapy and intravesical Bacillus Calmette-Guerin are considered. A significant theme is the polarization of immune responses within the tumor by a heavily immunosuppressive tumor microenvironment which affects the phenotype of multiple innate and adaptive populations. Throughout, clinical implications are discussed with suggestions for future research directions and therapeutic targeting.

Mechanisms of BCG immunotherapy and its outlook for bladder cancer

BCG immunotherapy is the gold-standard treatment for non-muscle-invasive bladder cancer at high risk of recurrence or progression. Preclinical and clinical studies have revealed that a robust inflammatory response to BCG involves several steps: attachment of BCG; internalization of BCG into resident immune cells, normal cells, and tumour urothelial cells; BCG-mediated induction of innate immunity, which is orchestrated by a cellular and cytokine milieu; and BCG-mediated initiation of tumour-specific immunity. As an added layer of complexity, variation between clinical BCG strains might influence development of tumour immunity. However, more than 40 years after the first use of BCG for bladder cancer, many questions regarding its mechanism of action remain unanswered. Clearly, a better understanding of the mechanisms underlying BCG-mediated tumour immunity could lead to improved efficacy, increased tolerance of treatment, and identification of novel immune-based therapies. Indeed, enthusiasm for bladder cancer immunotherapy, and the possibility of combining BCG with other therapies, is increasing owing to the availability of targeted immunotherapies, including checkpoint inhibitors. Understanding of the mechanism of action of BCG immunotherapy has advanced greatly, but many questions remain, and further basic and clinical research efforts are needed to develop new treatment strategies for patients with bladder cancer.

Interactions of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) with the Immune System: Implications for Inflammation and Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily. TRAIL has historically been distinct from the Fas ligand and TNFα in terms of selective apoptosis induction in tumor cells and has a nearly non-existent systemic toxicity. Consequently, in the search for an ideal drug for tumor therapy, TRAIL rapidly drew interest, promising effective tumor control with minimal side effects. However, euphoria gave way to disillusionment as it turned out that carcinoma cells possess or can acquire resistance to TRAIL-induced apoptosis. Additionally, studies on models of inflammation and autoimmunity revealed that TRAIL can influence immune cells in many different ways. While TRAIL was initially found to be an important player in tumor defense by natural killer cells or cytotoxic T cells, additional effects of TRAIL on regulatory T cells and effector T cells, as well as on neutrophilic granulocytes and antigen-presenting cells, became focuses of interest. The tumor-promoting effects of these interactions become particularly important for consideration in cases where tumors are resistant to TRAIL-induced apoptosis. Consequently, murine models have shown that TRAIL can impair the tumor microenvironment toward a more immunosuppressive type, thereby promoting tumor growth. This review summarizes the current state of knowledge on TRAIL’s interactions with the immune system in the context of cancer.

Improved antitumor efficacy of neutrophils stimulated by bacillus Calmette‑Guérin

Bacillus Calmette‑Guérin (BCG) has become a significant treatment for bladder cancer, and neutrophils are reported to be associated with the antitumor effect of BCG. The aim of the present study was to clarify the antitumor function of neutrophils stimulated by BCG. Initially, the killing effect and cytotoxic activity of neutrophils treated with BCG was detected. Subsequently, the effectiveness of BCG‑treated neutrophils extracted from tumor‑bearing mice was analyzed. The results revealed that the cytotoxic effect of neutrophils was stronger in the BCG‑treated group compared with that in the normal saline (NS)‑treated and control groups (P<0.05). A significantly higher concentration of cytokines tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β, IL‑6 and TNF‑related apoptosis‑inducing ligand occurred in the BCG‑treated neutrophil group compared with the NS and control groups (P<0.01), which was also associated with the BCG dose (P<0.01). The gross tumor volume percentage in BCG‑treated neutrophils from tumor‑bearing mice (BCGT group) was significantly lower in comparison with that in the NS‑treated neutrophils from tumor‑bearing mice (NST group; P<0.05). In addition, the survival rate of tumor‑bearing mice was higher in the BCGT group compared with the NST group (P<0.05), while more BCG‑treated neutrophils from tumor‑bearing mice were infiltrated in the MethA tumor (P<0.01). In conclusion, BCG‑treated neutrophils were observed to enhance the antitumor efficacy and extend the life span of mice.

Effectiveness of two different dose administration regimens of an IL-15 superagonist complex (ALT-803) in an orthotopic bladder cancer mouse model

BACKGROUND

We set out to determine if the administration of subcutaneous (SQ) ALT-803 was non-inferior to standard intravesical BCG treatment in a carcinogen induced mouse (C57BL/6J) bladder cancer model.

METHODS

Using this well-established carcinogen induced mouse model, we studied the effects of various dosing schemas of ALT-803 (SQ alone, SQ with intravesical BCG, intravesical alone, intravesical with intravesical BCG) compared to intravesical BCG alone (positive control) and PBS (negative control). The non-inferiority margin for the difference in bladder weight, as a surrogate for tumor mass, was defined as 7%.

RESULTS

All treatment groups (i.e., ALT-803 SQ alone, ALT-803 SQ with intravesical BCG, ALT-803 intravesical alone, ALT-803 intravesical with intravesical BCG and intravesical BCG alone) demonstrated a significant reduction in tumor burden as evident by bladder weights and H&E stain (p < 0.005). Non-inferiority tests between the intravesical BCG alone group and the additional treatment groups showed that SQ ALT-803 alone (p = 0.04) and BCG plus SQ ALT-803 (p = 0.009) were non-inferior to intravesical BCG alone. In this model, we did not see an appreciable infiltration of CD4⁺ T, CD8⁺ T or CD161/KLRB1⁺ natural killer (NK) cells in the bladder/tumor. When assessing peripheral blood mononuclear cells, SQ ALT-803 alone resulted in a robust induction of CD8⁺ T cells (p < 0.01), NKG2D⁺ NK cells (p < 0.005) and CD3⁺/NKG2D⁺ NKT cells (p < 0.005) compared to other groups, while in splenic tissue, SQ ALT-803 alone resulted in a robust induction of CD3⁺/NKG2D⁺ NKT cells (p < 0.005) compared to other groups.

CONCLUSION

Subcutaneous ALT-803 treatment alone or in combination with intravesical BCG was well tolerated and was not inferior to intravesical BCG alone. CD8⁺ T, NKG2D⁺ NK and CD3⁺/NKG2D⁺ NKT cell induction along with induction of key cytokines remain steadfast mechanisms behind ALT-803. The enhanced therapeutic index seen with BCG and ALT-803, administered SQ or intravesically, provides a powerful justification for the further development of these regimens.

SIU-ICUD consultation on bladder cancer: basic science

PURPOSE

To provide a condensed summary of the Basic Science chapter that was included in the Third International Consultation on Bladder Cancer.

METHODS

World bladder cancer basic science experts used the published literature to create summaries of recent progress in their areas of expertise.

RESULTS

The completion of several large-scale genomics projects coupled with a strong collaborative culture within the research community and the exciting clinical activity of immune checkpoint blockade have combined to transform the bladder cancer research landscape. Bladder cancer molecular subtypes and the presence of specific DNA alterations provide important information about disease heterogeneity that has direct implications for clinical management, and some can be targeted by compounds that are already clinically available. Tests are being developed that can measure many of these alterations non-invasively in peripheral blood or urine, raising confidence that they could be used as biomarkers for surveillance and monitoring the effects of local and systemic therapies.

CONCLUSIONS

Although the bulk of the mechanistic work lies ahead, the genomics results have created a hypothesis-generating description of bladder cancer heterogeneity that has set the stage for deeper mechanistic studies, and they have already provided us with extremely attractive candidate biomarkers to guide clinical practice. Here, we will summarize the recent progress in basic bladder cancer research and highlight near-term opportunities for the future.

Tumor-derived granzyme B-expressing neutrophils acquire antitumor potential after lipid A treatment

Neutrophils are known to possess both pro- and anti-tumor properties, a feature that could be related to the diversity and plasticity of these cells. Here we explored the hypothesis that under an appropriate environment and stimuli, neutrophils could induce an effective response against tumor cells. In a rat and mouse models, we show that a substantial amount of colon tumor associated-neutrophils (TAN) expressed the cytolytic enzyme granzyme B, which is absent in spleen or blood circulating neutrophils. This TAN population was also found into tumors of patients with colon cancer. Tumor neutrophil infiltration was correlated with an increase of chemokines known to attract neutrophils in both rat models and patients. These cells were involved in a Lipid A analog-mediated colon tumor regression. Mechanistically, treating the rats with the Lipid A analog triggered granzyme B release from neutrophils in tumor cell vicinity, which was correlated to tumor regression. Alteration of granzyme B function in tumor cells decreased the cytotoxic effect of Lipid A in rat and mouse models. Granzyme B expression in neutrophils could be induced by the lipid A analog but also by some of the cytokines that were detected in the tumor microenvironment. These results identify a subpopulation of neutrophils expressing granzyme B that can act as a key player of lipid A-mediated colon cancer regression in rat and mouse models and the molecular mechanisms involved may provide novel approaches for human therapeutic intervention.

TLR7 agonist in combination with Salmonella as an effective antimelanoma immunotherapy

AIM

We evaluated a novel approach combining the use of attenuated Salmonella immunotherapy with a Toll-like receptor agonist, imiquimod, in B16F1 melanoma-bearing mice.

MATERIALS & METHODS

B16F1 melanoma-bearing mice were daily treated with topical imiquimod in combination with one intratumoral injection of attenuated Salmonella enterica serovar Typhimurium LVR01.

RESULTS

The combined therapy resulted in retarded tumor growth and prolonged survival. Combination treatment led to an enhancement in the expression of pro-inflammatory cytokines and chemokines in the tumor microenvironment, with a Th1-skewed profile, resulting in a broad antitumor response. The induced immunity was effective in controlling the occurrence of metastasis.

CONCLUSION

Salmonella LVR01 immunotherapy in combination with imiquimod is a novel approach that could be considered as an effective antimelanoma therapy.

The Formation and Function of Granulomas

Granulomas are organized aggregates of macrophages, often with characteristic morphological changes, and other immune cells. These evolutionarily ancient structures form in response to persistent particulate stimuli-infectious or noninfectious-that individual macrophages cannot eradicate. Granulomas evolved as protective responses to destroy or sequester particles but are frequently pathological in the context of foreign bodies, infections, and inflammatory diseases. We summarize recent findings that suggest that the granulomatous response unfolds in a stepwise program characterized by a series of macrophage activations and transformations that in turn recruit additional cells and produce structural changes. We explore why different granulomas vary and the reasons that granulomas are protective and pathogenic. Understanding the mechanisms and role of granuloma formation may uncover new therapies for the multitude of granulomatous diseases that constitute serious medical problems while enhancing the protective function of granulomas in infections.

Neutrophils in Cancer: Two Sides of the Same Coin

Neutrophils are the most abundant leukocytes in blood and are considered to be the first line of defense during inflammation and infections. In addition, neutrophils are also found infiltrating many types of tumors. Tumor-associated neutrophils (TANs) have relevant roles in malignant disease. Indeed neutrophils may be potent antitumor effector cells. However, increasing clinical evidence shows TANs correlate with poor prognosis. The tumor microenvironment controls neutrophil recruitment and in turn TANs help tumor progression. Hence, TANs can be beneficial or detrimental to the host. It is the purpose of this review to highlight these two sides of the neutrophil coin in cancer and to describe recent studies that provide some light on the mechanisms for neutrophil recruitment to the tumor, for neutrophils supporting tumor progression, and for neutrophil activation to enhance their antitumor functions.

Tumor-Associated Macrophages Provide Significant Prognostic Information in Urothelial Bladder Cancer

Inflammation is an important feature of carcinogenesis. Tumor-associated macrophages (TAMs) can be associated with either poor or improved prognosis, depending on their properties and polarization. Current knowledge of the prognostic significance of TAMs in bladder cancer is limited and was investigated in this study. We analyzed 184 urothelial bladder cancer patients undergoing transurethral resection of a bladder tumor or radical cystectomy. CD68 (pan-macrophage marker), MAC387 (polarized towards type 1 macrophages), and CLEVER-1/Stabilin-1 (type 2 macrophages and lymphatic/blood vessels) were detected immunohistochemically. The median follow-up time was 6.0 years. High macrophage counts associated with a higher pT category and grade. Among patients undergoing transurethral resection, all studied markers apart from CLEVER-1/Stabilin-1 were associated with increased risk of progression and poorer disease-specific and overall survival in univariate analyses. High levels of two macrophage markers (CD68/MAC387^+/+ or CD68/CLEVER-1^+/+ groups) had an independent prognostic role after transurethral resection in multivariate analyses. In the cystectomy cohort, MAC387, alone and in combination with CD68, was associated with poorer survival in univariate analyses, but none of the markers were independent predictors of outcome in multivariate analyses. In conclusion, this study demonstrates that macrophage phenotypes provide significant independent prognostic information, particularly in bladder cancers undergoing transurethral resection.

Complications of intravesical bacillus calmette-guérin

Intravesical Bacillus Calmette-Guérin (BCG) is an important treatment for the management of non-muscle invasive bladder cancer because of its proven efficacy and favourable safety profile. The most common complications associated with BCG treatment are relatively minor. They include urinary frequency, cystitis, fever, and hematuria. Although serious complications are rare, patients can develop severe, life-threatening sepsis with disseminated mycobacterial infection. We report a rare case of periurethral diverticulum formation after intravesical BCG and review the literature on the potential complications of this treatment modality.

Construction of a recombinant-BCG containing the LMP2A and BZLF1 genes and its significance in the Epstein-Barr virus positive gastric carcinoma

The signal peptide Ag85B of Bacillus Chalmette-Guerin (BCG) was used to construct a recombinant plasmid of BCG. The BCG-Ag85B gene and fused EBV LMP2A and BZLF1 genes were amplified and successively inserted into the Escherichia coli-BCG shuttle-vector pMV261. The recombinant plasmids were then amplified in E. coli DH5α and transformed into competent BCG. The expression of BZLF1 and LMP2A fusion proteins in recombinant-BCG (rBCG) was shown by Western blot. After the injection of recombinant-BCG into mice, antibodies against the fusion protein BZLF1 and LMP2A were measured by ELISA, and the cellular immune effects were determined by the lactate dehydrogenate (LDH) release assays. The results confirmed that the cloned genes of BCG-Ag85B and Z2A were correctly inserted into the vector pMV261. The recombinant plasmid pMVZ2A expressed Z2A in BCG effectively after transformation. The rBCG proteins were recognized by the BZLF1 (LMP2A) antibody. An ELISA demonstrated that rBCG could stimulate the generation of antibody against the fusion protein. The fusion gene was constructed successfully, and the rBCG induced humoral and cellular immune response in mice.

On the cytokines produced by human neutrophils in tumors

Although traditionally viewed as short-lived innate immunity cells, only playing a crucial role in host defense toward infections, neutrophils have recently become subject of a new wave of research in diverse areas including in tumors. Indeed, increasing experimental evidence indicate that neutrophils may directly or indirectly influence the tumor fate through the release of a wide array of molecules able to exert either pro-tumor or anti-tumor functions depending on the microenvironment milieu, including cytokines. This review therefore attempts to uncover the role that neutrophils play during the different steps of tumor development (from promotion to progression), as well as in anti-tumor responses, via cytokine production.

CLT1 targets bladder cancer through integrin α5β1 and CLIC3

High-grade non-muscle-invasive bladder cancer is commonly treated with Bacillus Calmette-Guérin, an immunotherapeutic that depends on fibronectin and tumor cell integrin α5β1 for internalization into bladder cancer cells. We previously showed that the anti-angiogenic peptide CLT1 forms cytotoxic complexes with fibronectin that are cooperatively internalized into proliferating endothelium through ligation of integrins and chloride intracellular channel 1. While CLT1 has no effect on mature, differentiated cells, we show here that CLT1 is highly cytotoxic for a panel of bladder tumor cell lines as well as a variety of cell lines derived from kidney, lung, breast, and prostate cancer. Paralleling our previous results, we found CLT1-induced tumor cell death to be increased in the presence of fibronectin, which mediated CLT1 internalization and subsequent autophagic cell death in a mechanism that depends on tumor cell integrin α5β1 and chloride intracellular channel 3 (CLIC3). This mechanistic link was further supported by our results showing upregulation of α5β1 and CLIC3 in CLT1-responsive tumor cell lines and colocalization with CLT1 in tumor tissues. Incubating tumor tissue from patients with bladder cancer with fluorescein-conjugated CLT1 resulted in a strong and specific fluorescence whereas normal bladder tissue remained negative. On the basis of its affinity for bladder tumor tissue and strong antitumor effects, we propose that CLT1 could be useful for targeting bladder cancer.

Smac mimetic enables the anticancer action of BCG-stimulated neutrophils through TNF-α but not through TRAIL and FasL

BCG, the current gold standard immunotherapy for bladder cancer, exerts its activity via recruitment of neutrophils to the tumor microenvironment. Many patients do not respond to BCG therapy, indicating the need to understand the mechanism of action of BCG-stimulated neutrophils and to identify ways to overcome resistance to BCG therapy. Using isolated human neutrophils stimulated with BCG, we found that TNF-α is the key mediator secreted by BCG-stimulated neutrophils. RT4v6 human bladder cancer cells, which express TNFR1, CD95/Fas, CD95 ligand/FasL, DR4, and DR5, were resistant to BCG-stimulated neutrophil conditioned medium but effectively killed by the combination of conditioned medium and Smac mimetic. rhTNF-α and rhFasL, but not rhTRAIL, in combination with Smac mimetic, generated signature molecular events similar to those produced by BCG-stimulated neutrophils in combination with Smac mimetic. However, experiments using neutralizing antibodies to these death ligands showed that TNF-α secreted from BCG-stimulated neutrophils was the key mediator of anticancer action. These findings explain the mechanism of action of BCG and identified Smac mimetics as potential combination therapeutic agents for bladder cancer.

Mapping the cytokine profile of painful bladder syndrome/interstitial cystitis in human bladder and urine specimens

PURPOSE

This study investigated the cytokine profile in bladder tissue and urine of painful bladder syndrome/interstitial cystitis (PBS/IC) patients.

METHODS

Multiplex analysis of 23 cytokines was performed with a multiple antigen bead assay (Luminex 100 IS) on cold cup bladder biopsy and urine specimens collected during cystoscopy with hydrodistention (HD) under general anesthesia from 10 PBS/IC patients (ICS definition). Collected tissue specimens and urine from pre-HD and post-HD (mean 27 days) were compared to banked urine and tissue specimens (n = 10) collected from control subjects without PBS/IC symptoms.

RESULTS

Univariate comparison of bladder tissue levels found significant elevation of IL-16, IL-18, CTACK, ICAM-1, MCP-3, SCGFβ, TRAIL, and VCAM-1 in PBS/IC relative to controls. Multivariate analysis revealed VCAM-1 and ICAM-1 were responsible for the discrimination of both tissue and urine of PBS/IC from controls. Urine levels of MCP-3 and TRAIL were significantly reduced a month after HD in concert with improvement in standardized measures of clinical symptoms (pain, urgency, and frequency (PUF) overall score [mean 25.8 ± 5.5 vs. 20.3 ± 7, p = 0.04] and symptom score [mean 18.2 ± 3.2 vs. 12.2 ± 5.9; p = 0.009]). Post-HD urine levels of MCSF(r = 0.88; p = 0.003), MCP-3 (r = 0.81; p = 0.01), SDF1α (r = 0.82; p = 0.01), and IL-18 (r = 0.64; p = 0.08) positively correlated with improved symptom scores.

CONCLUSIONS

These results indicate significant elevation of cytokines in PBS/IC bladder tissue relative to controls. Significant reduction in post-HD urine levels of MCP-3 and TRAIL relative to pre-HD in PBS/IC was associated with clinical improvement (as measured by PBS/IC symptom scores) to qualify them as biomarker candidates.

Bacterial immunotherapy of gastrointestinal tumors

Background

Cancer immunotherapy using bacteria dates back over 150 years. The deeper understanding on how the immune system interferes with the tumor microenvironment has led to the re-emergence of bacteria or their related products in immunotherapeutic concepts. In this review, we discuss recent approaches on experimental bacteriolytic therapy, emphasizing the specific interplay between bacteria, immune cells and tumor cells to break the tumor-induced tolerance.

Results

Experimental research during the last decades demonstrated beneficial but also adverse influence of bacteria on tumor growth. There is a strong correlation between chronic infections and tumor incidence. However, acute bacterial infections have favourable effects on tumor growth often contributing to complete remission. Tumor regression is usually attributable to both direct tumor cell killing (via apoptosis and/or necrosis, depending on the applied bacteria) and indirect immune stimulation. This includes (I) elimination of immunosuppressive immune cells (i.e. tumor-associated macrophages, myeloid-derived suppressor, and regulatory T cells), (II) suppression of Th2-directed cytokine secretion (TGFα, IL10), (III) providing a pro-inflammatory micro-milieu (tumor infiltrating neutrophils) and (IV) supporting the influx of cytotoxic T cells into tumors. This finally forces the development of an immunological memory and may provide long-term protection against cancer.

Conclusion

Immunotherapy using bacteria is still a double-edged sword. Experiences from the last years have substantially contributed to when bacteria and defined components thereof might be integrated into immunotherapeutic concepts. Attempts in transferring this approach into the clinics are on their way.

The role of c-FLIP splice variants in urothelial tumours

Deregulation of apoptosis is common in cancer and is often caused by overexpression of anti-apoptotic proteins in tumour cells. One important regulator of apoptosis is the cellular FLICE-inhibitory protein (c-FLIP), which is overexpressed, for example, in melanoma and Hodgkin's lymphoma cells. Here, we addressed the question whether deregulated c-FLIP expression in urothelial carcinoma impinges on the ability of death ligands to induce apoptosis. In particular, we investigated the role of the c-FLIP splice variants c-FLIP(long) (c-FLIP(L)) and c-FLIP(short) (c-FLIP(S)), which can have opposing functions. We observed diminished expression of the c-FLIP(L) isoform in urothelial carcinoma tissues as well as in established carcinoma cell lines compared with normal urothelial tissues and cells, whereas c-FLIP(S) was unchanged. Overexpression and RNA interference studies in urothelial cell lines nevertheless demonstrated that c-FLIP remained a crucial factor conferring resistance towards induction of apoptosis by death ligands CD95L and TRAIL. Isoform-specific RNA interference showed c-FLIP(L) to be of particular importance. Thus, urothelial carcinoma cells appear to fine-tune c-FLIP expression to a level sufficient for protection against activation of apoptosis by the extrinsic pathway. Therefore, targeting c-FLIP, and especially the c-FLIP(L) isoform, may facilitate apoptosis-based therapies of bladder cancer in otherwise resistant tumours.

Molecular cloning, functional characterization and phylogenetic analysis of TRAIL in Japanese pufferfish Takifugu rubripes

In this study, the complementary DNA (cDNA) of Japanese pufferfish Takifugu rubripes tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) was cloned by reverse-transcription PCR. The open reading frame of the TRAIL consisted of 870 bases. The deduced amino-acid sequence of the TRAIL showed a high homology with the sequences of other teleosts. Recombinant soluble TRAIL was fused with a small ubiquitin-related modifier gene to enhance the soluble expression level in Escherichia coli BL21 (DE3). In vitro, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide (MTT) assay indicated that the purified soluble TRAIL was able to induce apoptosis of Jurkat and HeLa cells in a dose-dependent manner.

Immunotherapeutic efficacy of Mycobacterium indicus pranii in eliciting anti-tumor T cell responses: critical roles of IFNγ

Mycobacterium indicus pranii (MIP) is approved for use as an adjuvant (Immuvac/Cadi-05) in the treatment of leprosy. In addition, its efficacy is being investigated in clinical trials on patients with tuberculosis and different tumors. To evaluate and delineate the mechanisms by which autoclaved MIP enhances anti-tumor responses, the growth of solid tumors consisting of Sp2/0 (myeloma) and EL4 (thymoma) cells was studied in BALB/c and C57BL/6 mice, respectively. Treatment of mice with a single intra-dermal (i.d.) injection of MIP 3 days after Sp2/0 implantation greatly suppresses tumor growth. MIP treatment of tumor bearing mice lowers Interleukin (IL)6 but increases IL12p70 and IFNγ amounts in sera. Also, increase in CD8(+) T cell mediated lysis of specific tumor targets and production of high amounts of IL2 and IFNγ by CD4(+) T cells upon stimulation with specific tumor antigens in MIP treated mice is observed. Furthermore, MIP is also effective in reducing the growth of EL4 tumors; however, this efficacy is reduced in Ifnγ(-/-) mice. In fact, several MIP mediated anti-tumor responses are greatly abrogated in Ifnγ(-/-) mice: increase in serum Interleukin (IL)12p70 amounts, induction of IL2 and lysis of EL4 targets by splenocytes upon stimulation with specific tumor antigens. Interestingly, tumor-induced increase in serum IL12p70 and IFNγ and reduction in growth of Sp2/0 and EL4 tumors by MIP are not observed in nonobese diabetic severe combined immunodeficiency mice. Overall, our study clearly demonstrates the importance of a functional immune network, in particular endogenous CD4(+) and CD8(+) T cells and IFNγ, in mediating the anti-tumor responses by MIP.

Immunotherapy for urothelial carcinoma: current status and perspectives

Intravesical instillation of bacillus Calmette Guérin (BCG) for the treatment of urothelial carcinoma (UC) of the bladder is based on the BCG-induced immune response, which eradicates and prevents bladder cancer. The results of recent studies have suggested that not only major histocompatibility complex (MHC)-nonrestricted immune cells such as natural killer cells, macrophages, neutrophils, etc., but also MHC-restricted CD8⁺ T cells play an important role and are one of the main effectors in this therapy. Better understanding of the mechanism of BCG immunotherapy supports the idea that active immunotherapy through its augmented T cell response can have great potential for the treatment of advanced UC. In this review, progress in immunotherapy for UC is discussed based on data from basic, translational and clinical studies. We also review the escape mechanism of cancer cells from the immune system, and down-regulation of MHC class I molecules.

TRAIL-mediated signaling in prostate, bladder and renal cancer

Tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a death receptor ligand that has the ability to preferentially initiate apoptosis in malignant cells with minimal toxicity to normal cells. TRAIL-based therapeutics, including recombinant TRAIL, TRAIL-receptor agonistic antibodies and TRAIL gene therapy, have now entered clinical trials. Although these therapeutics are promising, concerns regarding TRAIL resistance are causing research efforts to shift towards the identification of effective combination therapies. Small-molecule inhibitors, natural compounds, and drugs approved for treatment of diseases other than cancer have been shown to affect TRAIL receptors, antiapoptotic proteins and survival pathways in prostate, bladder and renal cell lines and in preclinical models. Changes in endogenous TRAIL and TRAIL receptor expression during the development of genitourinary malignancies and the way in which the expression pattern is affected by treatment are of great interest, and understanding the biological consequences of such changes will be important to maximize the potential of TRAIL-based therapeutics.

Mycobacterium bovis bacillus Calmette-Guérin-induced macrophage cytotoxicity against bladder cancer cells

Many details of the molecular and cellular mechanisms involved in Mycobacterium bovis bacillus Calmette-Guérin (BCG) immunotherapy of bladder cancer have been discovered in the past decades. However, information on a potential role for macrophage cytotoxicity as an effector mechanism is limited. Macrophages play pivotal roles in the host innate immunity and serve as a first line of defense in mycobacterial infection. In addition to their function as professional antigen-presenting cells, the tumoricidal activity of macrophages has also been studied with considerable interest. Studies have shown that activated macrophages are potent in killing malignant cells of various tissue origins. This review summarizes the current understanding of the BCG-induced macrophage cytotoxicity toward bladder cancer cells with an intention to inspire investigation on this important but underdeveloped research field.