A NOVEL INTRAVESICAL THERAPY FOR SUPERFICIAL BLADDER CANCER IN AN ORTHOTOPIC MODEL: ONCOLYTIC REOVIRUS THERAPY

Evaluating a combination treatment of NK cells and reovirus against bladder cancer cells using an in vitro assay to simulate intravesical therapy

Intravesical treatment using either reovirus or natural killer (NK) cells serves as an efficient strategy for the treatment of bladder cancer cells (BCCs); however, corresponding monotherapies have often shown modest cytotoxicity. The potential of a locoregional combination using high-dose reovirus and NK cell therapy in an intravesical approach has not yet been studied. In this study, we evaluated the effectiveness of reoviruses and expanded NK cells (eNK) as potential strategies for the treatment of bladder cancer. The anti-tumor effects of mono-treatment with reovirus type 3 Dearing strain (RC402 and RP116) and in combination with interleukin (IL)-18/-21-pretreated eNK cells were investigated on BCC lines (5637, HT-1376, and 253J-BV) using intravesical therapy to simulate in vitro model. RP116 and IL-18/-21-pretreated eNK cells exhibited effective cytotoxicity against grade 1 carcinoma (5637 cells) when used alone, but not against HT-1376 (grade 2 carcinoma) and 253J-BV cells (derived from a metastatic site). Notably, combining RP116 with IL-18/-21-pretreated eNK cells displayed effective cytotoxicity against both HT-1376 and 253J-BV cells. Our findings underscore the potential of a combination therapy using reoviruses and NK cells as a promising strategy for treating bladder cancer.

Intravesical oncolytic virotherapy and immunotherapy for non-muscle-invasive bladder cancer mouse model

OBJECTIVES

To test if intravesical instillation of both an anti-programmed cell death protein 1 (PD-1) inhibitor and an oncolytic reovirus would demonstrate a greater effect than either treatment alone, as non-muscle-invasive bladder cancer that is refractory to intravesical bacillus Calmette-Guérin can be treated by systemic anti-PD-1 immunotherapy and we previously demonstrated improved overall survival (OS) with six once-weekly instillations of intravesical anti-PD-1 in a murine model.

MATERIALS AND METHODS

Using an orthotopic syngeneic C3H murine model of MBT2 urothelial bladder cancer, groups of 10 mice were compared between no treatment, intravesical anti-PD-1, intravesical oncolytic reovirus, or intravesical reovirus + anti-PD-1. A single intravesical treatment session was given. The primary outcome was OS, and the secondary outcomes included long-term immunity and tumour-immune profile.

RESULTS

With a median follow-up of 9 months, all mice that received no treatment died with a median survival of 41 days, while the comparison median OS was not reached for reovirus (hazard ratio [HR] 14.4, 95% confidence interval [CI] 3.9-32.6; P < 0.001), anti-PD-1 (HR 28.4, 95% CI 7.0-115.9; P < 0.001), and reovirus + anti-PD-1 (HR 28.4, 95% CI 7.0-115.9; P < 0.001). Monotherapy with anti-PD-1 or reovirus demonstrated no significant differences in survival (P = 0.067). Mass cytometry showed that reovirus + anti-PD-1 treatment enriched monocytes and decreased myeloid-derived suppressor cells, generating an immuno-responsive tumour microenvironment. Depletion of CD8+ T cells eliminated the survival advantage provided by the intravesical treatment.

CONCLUSIONS

Treatment of murine orthotopic bladder tumours with a single instillation of intravesical reovirus, anti-PD-1 antibody, or the combination confers superior survival compared to controls. Tumour-immune microenvironment differences indicated myeloid-derived suppressor cells and CD8+ T cells mediate the treatment response.

Associations of dietary isothiocyanate exposure from cruciferous vegetable consumption with recurrence and progression of non-muscle-invasive bladder cancer: findings from the Be-Well Study

BACKGROUND

High recurrence and progression rates are major clinical challenges for non-muscle-invasive bladder cancer (NMIBC). Dietary isothiocyanates (ITCs), phytochemicals primarily from cruciferous vegetables (CV), show strong anticancer activities in preclinical BC models, yet their effect on NMIBC prognosis remains unknown.

OBJECTIVES

This study aimed to investigate the associations of dietary ITC exposure at diagnosis with NMIBC recurrence and progression.

METHODS

The study analyzed 1143 participants from the Be-Well study, a prospective cohort of newly diagnosed NMIBC cases in 2015-2019 with no prior history of BC. Dietary ITC exposure was indicated by self-reported CV intake, estimated ITC intake, urinary metabolites, and plasma ITC-albumin adducts. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence and progression, and unconditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for delayed and multiple recurrence.

RESULTS

Over a mean follow-up of 25 mo, 347 (30%) developed recurrence and 77 (6.7%) had disease progression. Despite no significant associations with the overall risk of recurrence, urinary ITC metabolites (OR: 1.96; 95% CI: 1.01, 4.43) and dietary ITC intake (OR: 2.13; 95% CI: 1.03, 4.50) were associated with late recurrence after 12-mo postdiagnosis compared with before 12-mo postdiagnosis. Raw CV intake was associated with reduced odds of having ≥2 recurrences compared with having one (OR: 0.34; 95% CI: 0.16, 0.68). Higher plasma concentrations of ITC-albumin adducts were associated with a reduced risk of progression, including progression to muscle-invasive disease (for benzyl ITC, HR: 0.40; 95% CI: 0.17, 0.93; for phenethyl ITC, HR: 0.40; 95% CI: 0.19, 0.86).

CONCLUSIONS

Our findings indicate the possible beneficial role of dietary ITCs in NMIBC prognosis. Given the compelling preclinical evidence, increasing dietary ITC exposure with CV intake could be a promising strategy to attenuate recurrence and progression risks in patients with NMIBC.

Oncolytic Viruses for the Treatment of Bladder Cancer: Advances, Challenges, and Prospects

Bladder cancer is one of the most prevalent cancers. Despite recent advancements in bladder cancer therapy, new strategies are still required for improving patient outcomes, particularly for those who experienced Bacille Calmette-Guerin failure and those with locally advanced or metastatic bladder cancer. Oncolytic viruses are either naturally occurring or purposefully engineered viruses that have the ability to selectively infect and lyse tumor cells while avoiding harming healthy cells. In light of this, oncolytic viruses serve as a novel and promising immunotherapeutic strategy for bladder cancer. A wide diversity of viruses, including adenoviruses, herpes simplex virus, coxsackievirus, Newcastle disease virus, vesicular stomatitis virus, alphavirus, and vaccinia virus, have been studied in many preclinical and clinical studies for their potential as oncolytic agents for bladder cancer. This review aims to provide an overview of the advances in oncolytic viruses for the treatment of bladder cancer and highlights the challenges and research directions for the future.

Animal Models in Bladder Cancer

BACKGROUND

Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with an increasing incidence and mortality. Mouse models of bladder cancer should possess a high value of reproducibility, predictability, and translatability to allow mechanistic, chemo-preventive, and therapeutic studies that can be furthered into human clinical trials.

OBJECTIVES

To provide an overview and resources on the origin, molecular and pathological characteristics of commonly used animal models in bladder cancer.

METHODS

A PubMed and Web of Science search was performed for relevant articles published between 1980 and 2021 using words such as: "bladder" and/or "urothelial carcinoma" and animal models. Animal models of bladder cancer can be categorized as autochthonous (spontaneous) and non-autochthonous (transplantable). The first are either chemically induced models or genetically engineered models. The transplantable models can be further subclassified as syngeneic (murine bladder cancer cells implanted into immunocompetent or transgenic mice) and xenografts (human bladder cancer cells implanted into immune-deficient mice). These models can be further divided-based on the site of the tumor-as orthotopic (tumor growth occurs within the bladder) and heterotopic (tumor growth occurs outside of the bladder).

Using oncolytic viruses to ignite the tumour immune microenvironment in bladder cancer

The advent of immune checkpoint inhibition (ICI) has transformed the treatment paradigm for bladder cancer. However, despite the success of ICI in other tumour types, the majority of ICI-treated patients with bladder cancer failed to respond. The lack of efficacy in some patients could be attributed to a paucity of pre-existing immune reactive cells within the tumour immune microenvironment, which limits the beneficial effects of ICI. In this setting, strategies to attract lymphocytes before implementation of ICI could be helpful. Oncolytic virotherapy is thought to induce the release of damage-associated molecular patterns, eliciting a pro-inflammatory cytokine cascade and stimulating the activation of the innate immune system. Concurrently, oncolytic virotherapy-induced oncolysis leads to further release of neoantigens and subsequent epitope spreading, culminating in a robust, tumour-specific adaptive immune response. Combination therapy using oncolytic virotherapy with ICI has proven successful in a number of preclinical studies and is beginning to enter clinical trials for the treatment of both non-muscle-invasive and muscle-invasive bladder cancer. In this context, understanding of the mechanisms underpinning oncolytic virotherapy and its potential synergism with ICI will enable clinicians to effectively deploy oncolytic virotherapy, either as monotherapy or as combination therapy in the different clinical stages of bladder cancer.

Phase I Trial of an ICAM-1-Targeted Immunotherapeutic-Coxsackievirus A21 (CVA21) as an Oncolytic Agent Against Non Muscle-Invasive Bladder Cancer

PURPOSE

The CANON [CAVATAK in NON-muscle-invasive bladder cancer (NMIBC)] study evaluated a novel ICAM-1-targeted immunotherapeutic-coxsackievirus A21 as a novel oncolytic agent against bladder cancer.

PATIENTS AND METHODS

Fifteen patients enrolled in this "window of opportunity" phase I study, exposing primary bladder cancers to CAVATAK prior to surgery. The first 9 patients received intravesical administration of monotherapy CAVATAK; in the second stage, 6 patients received CAVATAK with a subtherapeutic dose of mitomycin C, known to enhance expression of ICAM-1 on bladder cancer cells. The primary endpoint was to determine patient safety and maximum tolerated dose (MTD). Secondary endpoints were evidence of viral replication, induction of inflammatory cytokines, antitumor activity, and viral-induced changes in resected tissue.

RESULTS

Clinical activity of CAVATAK was demonstrated by induction of tumor inflammation and hemorrhage following either single or multiple administrations of CAVATAK in multiple patients, and a complete resolution of tumor in 1 patient. Whether used alone or in combination with mitomycin C, CAVATAK caused marked inflammatory changes within NMIBC tissue biopsies by upregulating IFN-inducible genes, including both immune checkpoint inhibitory genes (PD-L1 and LAG3) and Th1-associated chemokines, as well as the induction of the innate activator RIG-I, compared with bladder cancer tissue from untreated patients. No significant toxicities were reported in any patient, from either virus or combination therapy.

CONCLUSIONS

The acceptable safety profile of CAVATAK, proof of viral targeting, replication, and tumor cell death together with the virus-mediated increases in "immunological heat" within the tumor microenvironment all indicate that CAVATAK may be potentially considered as a novel therapeutic for NMIBC.

Oncolytic Immunotherapy for Bladder Cancer Using Coxsackie A21 Virus

As a clinical setting in which local live biological therapy is already well established, non-muscle invasive bladder cancer (NMIBC) presents intriguing opportunities for oncolytic virotherapy. Coxsackievirus A21 (CVA21) is a novel intercellular adhesion molecule-1 (ICAM-1)-targeted immunotherapeutic virus. This study investigated CVA21-induced cytotoxicity in a panel of human bladder cancer cell lines, revealing a range of sensitivities largely correlating with expression of the viral receptor ICAM-1. CVA21 in combination with low doses of mitomycin-C enhanced CVA21 viral replication and oncolysis by increasing surface expression levels of ICAM-1. This was further confirmed using 300-μm precision slices of NMIBC where levels of virus protein expression and induction of apoptosis were enhanced with prior exposure to mitomycin-C. Given the importance of the immunogenicity of dying cancer cells for triggering tumor-specific responses and long-term therapeutic success, the ability of CVA21 to induce immunogenic cell death was investigated. CVA21 induced immunogenic apoptosis in bladder cancer cell lines, as evidenced by expression of the immunogenic cell death (ICD) determinant calreticulin, and HMGB-1 release and the ability to reject MB49 tumors in syngeneic mice after vaccination with MB49 cells undergoing CVA21 induced ICD. Such CVA21 immunotherapy could offer a potentially less toxic, more effective option for the treatment of bladder cancer.

Deletion of F4L (ribonucleotide reductase) in vaccinia virus produces a selective oncolytic virus and promotes anti-tumor immunity with superior safety in bladder cancer models

Bladder cancer has a recurrence rate of up to 80% and many patients require multiple treatments that often fail, eventually leading to disease progression. In particular, standard of care for high-grade disease, Bacillus Calmette-Guérin (BCG), fails in 30% of patients. We have generated a novel oncolytic vaccinia virus (VACV) by mutating the F4L gene that encodes the virus homolog of the cell-cycle-regulated small subunit of ribonucleotide reductase (RRM2). The F4L-deleted VACVs are highly attenuated in normal tissues, and since cancer cells commonly express elevated RRM2 levels, have tumor-selective replication and cell killing. These F4L-deleted VACVs replicated selectively in immune-competent rat AY-27 and xenografted human RT112-luc orthotopic bladder cancer models, causing significant tumor regression or complete ablation with no toxicity. It was also observed that rats cured of AY-27 tumors by VACV treatment developed anti-tumor immunity as evidenced by tumor rejection upon challenge and by ex vivo cytotoxic T-lymphocyte assays. Finally, F4L-deleted VACVs replicated in primary human bladder cancer explants. Our findings demonstrate the enhanced safety and selectivity of F4L-deleted VACVs, with application as a promising therapy for patients with BCG-refractory cancers and immune dysregulation.

Insights from animal models of bladder cancer: recent advances, challenges, and opportunities

Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with increasing incidence and mortality. Treatment of bladder cancer has not advanced in the past 30 years. Therefore, there is a crucial unmet need for novel therapies, especially for high grade/stage disease that can only be achieved by preclinical model systems that faithfully recapitulate the human disease. Animal models are essential elements in bladder cancer research to comprehensively study the multistep cascades of carcinogenesis, progression and metastasis. They allow for the investigation of premalignant phases of the disease that are not clinically encountered. They can be useful for identification of diagnostic and prognostic biomarkers for disease progression and for preclinical identification and validation of therapeutic targets/candidates, advancing translation of basic research to clinic. This review summarizes the latest advances in the currently available bladder cancer animal models, their translational potential, merits and demerits, and the prevalent tumor evaluation modalities. Thereby, findings from these model systems would provide valuable information that can help researchers and clinicians utilize the model that best answers their research questions.

Local Immune Stimulation by Intravesical Instillation of Baculovirus to Enable Bladder Cancer Therapy

Intravesical instillation of Bacillus Calmette-Guérin is currently used as adjuvant therapy for superficial, non-muscle invasive bladder cancer (NMIBC). However, nearly 40% of patients with NMIBC will fail Bacillus Calmette-Guérin therapy. In an attempt to investigate the feasibility of using insect baculovirus-based vectors for bladder cancer therapy, we observed that intravesical instillation of baculoviruses without transgene up-regulated a set of Th1-type of cytokines and increased the survival rate of mice bearing established orthotopic bladder tumors. When baculoviral vectors were used to co-deliver the mouse CD40 ligand and IL-15 genes through intravesical instillation, the immunogene therapy triggered significantly increased bladder infiltrations of inflammatory monocytes, CD4⁺, CD8⁺ and γδ T lymphocytes. All treated animals survived beyond 12 months whereas control animals died around 2 months after tumor inoculation. We conclude that direct intravesical instillation of baculoviral gene transfer vectors holds the potential to be a novel therapeutic modality for NMIBC.

Therapeutic Effect on Bladder Cancer with a Conditionally Replicating Oncolytic Virus Derived from Type II Herpes Simplex Virus

Purpose:

Despite recent improvements, resistance to traditional immunotherapy or chemotherapy is still common in patients with bladder cancer. We constructed an oncolytic virus from herpes simplex virus type II (HSV-2), which selectively targets tumor cells with an activated Ras signaling pathway. We evaluated the antitumor effect of this oncolytic HSV-2 (FusOn-H2) against bladder cancer, and compared with that of a first generation oncolytic virus derived from HSV-1 (Baco-1).

Materials and methods:

We established bladder tumor at the orthotopic site in C3H/He mice using the MBT-2 cells. Baco-1 or FusOn-H2 was instilled into the bladder through the urethra respectively. Tumor volume and weight were recorded by the end of the experiment. Animal spleens were also collected to determine if any anti-tumor immunity was elicited during virotherapy in this syngeneic bladder cancer model.

Results:

Two instillations of the oncolytic HSVs into bladder of tumor-bearing mice almost completely eradicated the tumor in majority of tumor bearing mice. The results of tumor-specific cytotoxic T lymphocyte activity assay showed that tumor destruction by oncolytic viruses in vivo, especially by the FusOn-H2, induced potent anti-tumor immune responses.

Conclusion:

Oncolytic virus derived from HSV-2 has potent anti-tumor activity against bladder cancer. Oncolytic effect of this virus in vivo induces tumor specific cellular immunity that further enhances the overall anti-tumor activity. Translating this novel virotherapy into the clinic could present an alternative intravesical therapy strategy for patients with bladder cancer.

Current animal models of bladder cancer: Awareness of translatability (Review)

Experimental animal models are crucial in the study of biological behavior and pathological development of cancer, and evaluation of the efficacy of novel therapeutic or preventive agents. A variety of animal models that recapitulate human urothelial cell carcinoma have thus far been established and described, while models generated by novel techniques are emerging. At present a number of reviews on animal models of bladder cancer comprise the introduction of one type of method, as opposed to commenting on and comparing all classifications, with the merits of a certain method being explicit but the shortcomings not fully clarified. Thus the aim of the present study was to provide a summary of the currently available animal models of bladder cancer including transplantable (which could be divided into xenogeneic or syngeneic, heterotopic or orthotopic), carcinogen-induced and genetically engineered models in order to introduce their materials and methods and compare their merits as well as focus on the weaknesses, difficulties in operation, associated problems and translational potential of the respective models. Findings of these models would provide information for authors and clinicians to select an appropriate model or to judge relevant preclinical study findings. Pertinent detection methods are therefore briefly introduced and compared.

REO-001: A phase I trial of percutaneous intralesional administration of reovirus type 3 dearing (Reolysin®) in patients with advanced solid tumors

PURPOSE

This open-labeled, phase I clinical trial was designed to determine the safety and tolerability of percutaneous intralesional administration of wild-type oncolytic revovirus type 3 Dearing (Reolysin®) in cancer patients with accessible and evaluable disease, who had otherwise failed to improve on standard cancer interventions.

EXPERIMENTAL DESIGN

An escalating dose of Reolysin® starting from up to 10(10) plague forming units (PFU) was administered to each cohort of three patients per dose level. Viral shedding, reovirus neutralizing antibody response, toxicity and clinical response were assessed.

RESULTS

Nineteen patients with various advanced solid tumors were treated. The most common toxicities related to treatment were grade 2 (or less) local erythema and transient flu like symptoms. Viral shedding was not seen in cerebral spinal fluid (CSF), urine and stool samples in all patients. Rising viral antibody titres were seen in all patients. In addition, we observed some evidence of local target tumor response activity in 7/19 patients (37 %) at the end of six or more weeks follow-up, with one patient exhibiting a complete response (CR), two a partial response (PR), and four stable disease (SD) to the local injected lesion.

CONCLUSIONS

Reolysin® is well tolerated given intralesionaly, with DLT/MTD not reached at a dose of 10(10) PFU. The favorable toxicity profile, lack of viral shedding and possible therapeutic activity has made this unattenuated oncolytic reovirus an attractive cancer therapeutic agent for ongoing clinical studies, including in the setting of locally advanced accessible disease for palliation of symptoms.

Oncolytic viruses in the treatment of bladder cancer

Bladder carcinoma is the second most common malignancy of the urinary tract. Up to 85% of patients with bladder cancer are diagnosed with a tumor that is limited to the bladder mucosa (Ta, T1, and CIS). These stages are commonly termed as non-muscle-invasive bladder cancer (NMIBC). Although the treatment of NMIBC has greatly improved in recent years, there is a need for additional therapies when patients fail bacillus Calmette-Guérin (BCG) and chemotherapeutic agents. We propose that bladder cancer may be an ideal target for oncolytic viruses engineered to selectively replicate in and lyse tumor cells leaving normal cells unharmed. In support of this hypothesis, here we review current treatment strategies for bladder cancer and their shortcomings, as well as recent advancements in oncolytic viral therapy demonstrating encouraging safety profiles and antitumor activity.

Combination of a fusogenic glycoprotein, pro-drug activation and oncolytic HSV as an intravesical therapy for superficial bladder cancer

Background:

There are still no effective treatments for superficial bladder cancer (SBC)/non-muscle invasive bladder cancer. Following treatment, 20% of patients still develop metastatic disease. Superficial bladder cancer is often multifocal, has high recurrences after surgical resection and recurs after intravesical live Bacillus Calmette–Guérin. Oncovex^GALV/CD, an oncolytic herpes simplex virus-1, has shown enhanced local tumour control by combining oncolysis with the expression of a highly potent pro-drug activating gene and the fusogenic glycoprotein.

Methods:

In vitro fusion/prodrug/apoptotic cell-based assays. In vivo orthotopic bladder tumour model, visualised by computed microtomography.

Results:

Treatment of seven human bladder carcinoma cell lines with the virus resulted in tumour cell killing through oncolysis, pro-drug activation and glycoprotein fusion. Oncovex^GALV/CD and mitomycin C showed a synergistic effect, whereas the co-administration with cisplatin or gemcitabine showed an antagonistic effect in vitro. Transitional cell cancer (TCC) cells follow an apoptotic cell death pathway after infection with Oncovex^GALV/CD with or without 5-FC. In vivo results showed that intravesical treatment with Oncovex^GALV/CD + prodrug (5-FC) reduced the average tumour volume by over 95% compared with controls.

Discussion:

Our in vitro and in vivo results indicate that Oncovex^GALV/CD can improve local tumour control within the bladder, and potentially alter its natural history.

Antitumor Efficacy of Intravesical BCG, Gemcitabine, Interferon-α and Interleukin-2 as Mono- or Combination-Therapy for Bladder Cancer in an Orthotopic Tumor Model

Objective:

To reduce adverse effects and improve efficacy of intravesical BCG for bladder cancer, alternative treatment options were investigated in an orthotopic rat tumor model.

Methods:

Superficial bladder cancer was established in syngeneic female rat bladders by instillation of AY-27 cells. Animals were randomly assigned to treatment groups including dose escalation of intravesical BCG with or without interferon-α (IFN-α) or interleukin-2 (IL-2); or graded doses of gemcitabine alone; or BCG plus gemcitabine. Treatments were given twice weekly for 3 weeks. Rats in control groups received saline instillations. Treatment response was monitored by animals’ well-being, survival days, tumor growth inhibition, and histological examination at necropsy.

Results:

Rats receiving monotherapy with intravesical BCG, gemcitabine, or IFN-α, attained significantly better survival and tumor reduction compared with control (P = 0.002; 0.001; 0.002, respectively, Log-rank Test). A dose-dependent treatment response was observed in animals with established bladder tumor receiving escalated BCG instillations. Only high-dose BCG significantly improved animal survival. Although high-dose BCG plus gemcitabine or IFN-α did not increase benefit over monotherapies, low-dose BCG plus IL-2 did show improved efficacy (P = 0.01).

Conclusion:

Intravesical monotherapies with gemcitabine and IFN-α were as effective as BCG for treatment of early non-muscle-invasive urothelial bladder cancer in this immune competent rat model. Combining these agents with high-dose BCG did not further increase efficacy. However, combining low-dose BCG with IL-2 enhanced BCG effectiveness.

Intake of cruciferous vegetables modifies bladder cancer survival

BACKGROUND

Intake of cruciferous vegetables, a rich source of dietary isothiocyanates, has been inversely associated with risk of bladder cancer. Due to the potent antiproliferative effects of dietary isothiocyanates on bladder cancer in in vitro and in vivo models, cruciferous vegetable intake may also play a role in survival among patients with bladder cancer.

METHODS

Using information obtained from the Roswell Park Cancer Institute Tumor Registry, patient medical records, and routinely collected questionnaire data, we examined potential associations between intake of cruciferous vegetables and survival among bladder cancer patients. As cooking can substantially reduce or destroy isothiocyanates, consumption of raw versus cooked cruciferous vegetables was examined separately. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard models.

RESULTS

A total of 239 bladder cancer patients were included in the study. After an average of 8 years of follow-up, 179 deaths occurred, with 101 deaths attributable to bladder cancer. After adjustment for other prognostic factors, a strong and significant inverse association was observed between bladder cancer mortality and broccoli intake, in particular raw broccoli intake (> or =1 versus <1 serving per month; HR for overall death, 0.57; 95% CI, 0.39-0.83; HR for disease-specific death, 0.43; 95% CI, 0.25-0.74). There were no significant associations for total vegetables, total fruits, or other individual cruciferous vegetables.

CONCLUSIONS

Considering the strong preclinical evidence, intake of broccoli may improve bladder cancer survival.

IMPACT

Further prospective investigation is warranted to confirm the potential role of cruciferous vegetables in bladder cancer prognosis.

Reovirus-based therapy for cancer

Reovirus is an oncolytic virus that is not associated with significant disease in humans, but is selectively able to replicate in cancer cells through exploitation of abnormal Ras signaling. Pre-clinical studies have demonstrated that treatment with reovirus is associated with significant anticancer activity across a range of tumor types. Reolysin is a proprietary formulation of the human reovirus developed by Oncolytics Biotech. Clinical evaluation of reovirus therapy has shown that it is well tolerated when administered locally or systemically. Encouraging anticancer efficacy has been observed with single-agent treatment and in combination with chemotherapy and radiotherapy. Phase II studies are currently evaluating reovirus alone and in combination with standard therapy in an array of tumor types. While immune sensitization hinders the anticancer efficacy of reovirus, it is important in preventing systemic toxicity. Immunosuppressive strategies are being developed that reduce immune neutralization of the virus to allow for improved tumor penetration, but retain sufficient antibody levels to protect normal tissues. The lack of toxicity and promising efficacy of reovirus has raised hopes that it will become an established anticancer agent.

Oncolytic viral therapy using reovirus

Current mainstays in cancer treatment such as chemotherapy, radiation therapy, hormonal manipulation, and even targeted therapies such as trastuzumab (Herceptin) for breast cancer or erlotinib (Tarceva) for non-small cell lung cancer are limited by lack of efficacy, cellular resistance, and toxicity. Dose escalation and combination therapies designed to overcome resistance and increase efficacy are limited by a narrow therapeutic index. Oncolytic viruses are one such group of new biological therapeutics that appears to have a wide spectrum of anticancer activity with minimal human toxicity. Because the malignant phenotype of tumours is the culmination of multiple mutations that occur in several genes eventually leading to aberrant signalling pathways, oncolytic viruses, either natural or engineered, specifically target tumour cells, taking advantage of this cellular deviant signalling for their replication. Reovirus is one such naturally occurring double-stranded RNA (dsRNA) virus that exploits altered Ras signalling pathways in a myriad of cancers. The ability of reovirus to infect and lyse tumours both solid and haematological, under in vitro, in vivo, and ex vivo conditions, is discussed in this chapter. The major mechanism of reovirus oncolysis of cancer cells has been shown to occur through apoptosis. In addition, the synergistic anti-tumour effects of reovirus in combination with radiation or chemotherapy has also been demonstrated for reovirus-resistant and moderately sensitive tumours. In most of the clinical trials undertaken to date, an anti-reovirus immune response has been seen likely circumventing efficacy. Investigation into the use of reovirus as an immune adjuvant is currently underway to try and re-direct this immune response to tumour. Reovirus phase I clinical trials have shown indications of efficacy and several phase I/II trials are ongoing at present. The extensive pre-clinical efficacy, replication competency, and low toxicity profile in humans has placed the reovirus as an attractive anti-cancer therapeutic for ongoing clinical testing.

[Oncolytic vesicular stomatitis viruses as intravesical agents against non-muscle-invasive bladder cancer]

Patients with high-risk bladder cancer who do not respond to bacillus Calmette-Guerin (BCG) immunotherapy represent a significant therapeutic challenge. The addition of interferon to BCG has recently evolved as a second-line treatment option; however, many high-grade tumors are nonresponsive to interferon. Thus, replication-competent oncolytic vesicular stomatitis viruses (VSV) that selectively target interferon-refractory tumors are promising intravesical agents. In vitro, wild-type VSV as well as a mutant variant (AV3) that has an impaired ability to shut down innate immunity preferentially killed undifferentiated, interferon-nonresponsive bladder cancer cells. Testing of these viruses in an orthotopic murine model of high-grade bladder cancer, which we have recently validated, revealed that both AV3 and wild-type VSV significantly inhibited orthotopic tumor growth. Despite the use of immunocompromised nude mice, there was no evidence of toxicity. In conclusion, VSV instillation therapy demonstrated strong antitumor activity and safety in an orthotopic model of high-risk disease. These findings provide preclinical proof-of-principle for the intravesical use of VSV, especially in interferon-refractory patients.

Oncolytic vesicular stomatitis viruses are potent agents for intravesical treatment of high-risk bladder cancer

Bladder cancer is the second most common genitourinary malignancy. At initial diagnosis, approximately 70% of cases are non-muscle-invasive; however, current treatment options for superficial disease are of limited efficacy because many patients will develop recurrent tumors. The purpose of this study was to examine two replication-competent oncolytic vesicular stomatitis virus (VSV) strains as intravesical agents in an orthotopic murine model of high-grade bladder cancer. Four human bladder cancer cell lines (RT4, MGH-U3, UM-UC3, and KU-7) were treated with either wild-type VSV or a mutant Delta51M variant (AV3) in vitro. Both wild-type VSV and AV3, which has an impaired ability to shutdown innate immunity, preferentially killed the more aggressive, IFN-nonresponsive cell lines UM-UC3 and KU-7, whereas IFN-responsive RT4 and MGH-U3 cells were less susceptible. In vivo, KU-7-luc bladder tumor cells, which stably express firefly luciferase, were inoculated into nude mice by intravesical instillation and tumor growth was quantified using bioluminescence imaging. Mice with established xenografts were administered VSV intravesically on days 4, 9, and 14, and necropsy was performed after 3 weeks. AV3 as well as wild-type VSV significantly inhibited KU-7-luc tumor growth by 90% (AV3) and 98% (wild-type), respectively, as compared with controls treated with UV-inactivated VSV. Despite using immunocompromised hosts, there was no evidence of toxicity in either group. In conclusion, VSV instillation therapy showed promising antitumor activity and safety in an orthotopic model of bladder cancer. These findings provide preclinical proof-of-principle for the intravesical use of VSV against non-muscle-invasive bladder cancer, especially in IFN-refractory patients.

Evaluation of an orthotopic rat bladder urothelial cell carcinoma model by cystoscopy

OBJECTIVES

To enable preclinical testing of intravesical therapies against non-muscle-invasive bladder cancer (NMIBC) in an orthotopic rat bladder tumour model, augmented by the use of serial cystoscopy for in vivo tumour assessment and follow-up.

MATERIALS AND METHODS

Fischer F344 rats had a 16-G transurethral cannula placed. The bladder mucosa was conditioned with an acid rinse, followed by a 1-h instillation of 1.5 x 10(6) AY-27 rat bladder urothelial cell carcinoma (UCC) cells (day 0). Cystoscopy (1 mm) was done on day 0 (control) and at 3, 4, 5, 6, 7, 10, 13 and 17 days. At the scheduled times the rats were killed after cystectomy (four at each time) for histopathological examination of the bladder.

RESULTS

Overall, tumour establishment was >80%, with predominantly carcinoma in situ preceding or concomitant with invasive tumour growth. All tumours were formed at 3-5 days, and remained non-muscle-invasive up to 5 days. From 6 days, tumours progressed to muscle-invasive disease in 40% of the rats. Visibility at cystoscopy was excellent and tumours were apparent in >90% of rats from 5 days on, with a specificity and sensitivity of >90%. Cystoscopy could not distinguish NMIBC from muscle-invasive disease.

CONCLUSIONS

This is a reliable model of orthotopic rat bladder UCC, with early high-grade NMIBC growth, immediately followed by muscle-invasive growth, i.e. the recommended time to start intravesical therapy would be 5 days after tumour cell inoculation. Tumour growth can easily be monitored by cystoscopy, but cannot be used to distinguish NMIBC from muscle-invasive bladder cancer.

Intravesical ultrasonography for tumor staging in an orthotopically implanted rat model of bladder cancer

PURPOSE

Noninvasive and serial evaluation of tumor development and growth is important in an orthotopic animal bladder tumor model. However, to our knowledge a reliable method has not been established. We determined the usefulness of intravesical ultrasonography for tumor staging and volumetric assessment in an animal model.

MATERIALS AND METHODS

Tumors with various stages were formed in 20 female Fischer F344 rats by implanting AY-27 rat bladder carcinoma cells. Cells were implanted by instilling a suspension (4x10 cells) into the bladder cavity after urothelial denudation using hydrochloric acid or by directly injecting the cell suspension into the bladder wall. Tumor volume and invasion depth were measured by intravesical ultrasonography using an ultrathin 2.5Fr intraluminal ultrasound catheter via the urethra 7 to 10 days after cancer cell implantation. The rats were then sacrificed for histopathological examination.

RESULTS

All rats showed bladder tumors 7 to 10 days after cancer cell implantation, of which stages varied from superficial to advanced disease. Intravesical ultrasonography showed a clear cross-sectional view of all layers of the bladder wall and enabled visualization of bladder tumors (minimal 0.5 mm in diameter). This approach also provided an accurate diagnosis of tumor invasion into muscle layers and perivesical tissues with precise invasion depth and tumor size. The positive predictive ratio regarding tumor staging reached 85%. Repeat examinations were feasible without noticeable adverse effects.

CONCLUSIONS

Intravesical ultrasonography is a reliable and appropriate noninvasive method for evaluating tumor stage and size in an orthotopic rat bladder tumor model.

Intravesical mitomycin C for superficial transitional cell carcinoma

Intravesical instillation of mitomycin C after a transurethral resection of a bladder tumor constitutes a standard treatment modality in the management of superficial transitional cell carcinoma in the urinary bladder. An immediate instillation of mitomycin C after transurethral resection has been shown to reduce the recurrence rate of superficial transitional cell carcinoma. Intravesical mitomycin C is generally considered to be a safe treatment option, but the past few years have seen the publication of a number of case reports on severe complications following mitomycin C instillation. This article reports on the mode of action, as well as the intravesical effects and current indications for mitomycin C instillation. This review will summarize the oncological benefits of mitomycin C in comparison with other intravesical treatments, such as bacillus Calmette-Guérin, and elucidate the incidence and types of possible complications associated with intravesical mitomycin C chemotherapy.

Not all viruses are bad guys: the case for reovirus in cancer therapy

Efforts to improve on cancer therapy have begun to capitalize on recent advances in our understanding of tumorigenesis. Tumor-specific characteristics are being exploited to develop selective antibodies and pharmacological inhibitors that specifically target cancer cells, and these agents are already showing clinical promise. None of these approaches, however, has captured our imagination as much as the use of replication-competent viruses to kill cancer cells. Whereas normal cells resist replication, tumor cells have an impaired antiviral response that sensitizes them to oncolytic viruses. One such virus is reovirus, a benign, naturally occurring virus that can effect tumor regression in animal models. Reovirus is demonstrating much promise in pre-clinical studies of cancer therapy and in clinical trials, where a lack of toxicity and signs of efficacy are generating excitement for this novel potential cancer therapeutic.