Bacillus Calmette-Guérin treatment of non-muscle invasive bladder cancer

Bacillus Calmette-Guerin (BCG) immunotherapy for bladder cancer: current understanding and perspectives on engineered BCG vaccine

Since the first report in 1976, accumulated clinical evidence has supported intravesical Bacillus Calmette-Guerin (BCG) therapy as one of the standard methods of management of intermediate- and high-risk non-muscle invasive bladder cancer. Despite its efficacy, intravesical BCG therapy is associated with a variety of adverse events (AEs), most of which are tolerable or controllable with supportive care. However, some patients receiving intravesical BCG therapy may experience uncommon but severe AEs, leading to cessation of BCG therapy. Not all, but most severe AEs result from either local or systemic infection with live BCG. Intravesical instillation of BCG elicits multiple immune reactions, although the precise immunological mechanism of BCG therapy is not clear. It is convenient to separate the complex reactions into the following three categories: infection of urothelial cells or bladder cancer cells, induction of immune reactions, and induction of antitumor effects. Recently, our knowledge about each category has increased. Based on this understanding, predictors of the efficacy of intravesical BCG therapy, such as urinary cytokine measurement and cytokine gene polymorphism, have been investigated. Recently, preclinical studies using a novel engineered mycobacterium vaccine have been conducted to overcome the limitations of BCG therapy. One approach is Th1 cytokine-expressing recombinant forms of BCG; another approach is development of non-live bacterial agents to avoid AEs due to live BCG infection. We also briefly describe our approach using an octaarginine-modified liposome-incorporating BCG cell wall component to develop future substitutes for live BCG.

Results of a phase 1 dose escalation study of intravesical TMX-101 in patients with nonmuscle invasive bladder cancer

PURPOSE

Imiquimod, a toll like receptor 7 (TLR-7) agonist, is effective as a topical treatment for skin malignancies. TMX-101 is a liquid formulation of imiquimod. In this study we establish a safety profile of TMX-101 in patients with nonmuscle invasive bladder cancer.

MATERIALS AND METHODS

We conducted a multicenter phase 1 dose escalation study in patients with nonmuscle invasive bladder cancer. Patients were included in 1 of 4 dose groups (0.05%, 0.1%, 0.2% or 0.4%) and treated with 6 weekly instillations of TMX-101, starting 2 weeks after transurethral resection of bladder tumor. Patients were evaluated weekly, and pharmacokinetic and pharmacodynamic parameters were measured.

RESULTS

A total of 16 patients were included in the study with 4 per dose group. Two patients dropped out after instillation 2 in dose groups 1 and 2. Overall, 88 instillations were administered without serious adverse events. There were 118 adverse events, of which 84 were related to the study drug. All adverse events were mild or moderate and number or severity was not correlated with dose group. Of the related adverse events 70% were confined to the genitourinary tract and resolved without intervention. There was a dose dependent systemic uptake with low plasma levels up to dose group 3 (0.2%, 100 mg). Maximum plasma concentration in dose group 4 (0.4%, 200 mg) was 71.7 ng/ml. This is below plasma concentrations of 123 and 128 ng/ml without significant side effects measured in healthy volunteers after subcutaneous (30 mg) or oral intake (100 mg) of imiquimod, respectively.

CONCLUSIONS

Intravesical treatment with TMX-101 is safe. The side effects are common but mild and mostly limited to the genitourinary tract. There is a low systemic uptake.

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.

Cancer chemoprevention: successes and failures

BACKGROUND

Cancer has traditionally been considered a single disease, but it is now known to be far more complex, with an unfolding etiology. In less than 2 centuries, hundreds--if not thousands--of drugs for the treatment of cancer and for palliative care have been developed and tested, with 143 having achieved approval by the US Food and Drug Administration (MediLexicon International; "Cancer Drugs & Oncology Drugs," http://www.medilexicon.com/drugs-list/cancer.php). Just 13 agents have been approved, however, for treating precancerous lesions or for reducing risk.

CONTENT

Nonsteroidal antiinflammatory drugs, vitamins, food constituents and spice components, antidiabetic drugs, ω-3 fatty acids, and fiber are just a few of the many classes of compounds that have been tested for their cancer-preventive potential. We highlight some of the agents that have been scrutinized by way of randomized clinical trials in humans for their cancer prevention potential. We summarize the major definitive cancer chemoprevention studies that (a) were successful in demonstrating efficacy and ultimately received regulatory approval; (b) were not successful in demonstrating efficacy or had unacceptable toxicities, but from which the field has learned important lessons; and (c) showed compelling efficacy against surrogate end points but failed to achieve regulatory approval because of a lack of consensus regarding the relevance of those end points to clinical benefit.

SUMMARY

Chemopreventive studies have provided new insights into early disease pathogenesis, stimulated new risk assessments and models, fostered important research in end point biomarkers, and led to 13 approved agents. The development of safe and effective chemopreventive agents holds tremendous potential for reducing the burden of cancer.

Bilateral symmetrical corneal melting following intravesical Bacille Calmette-Guerin therapy for bladder carcinoma

A 63-year-old man with unremarkable previous ocular history presented with bilateral symmetrical corneal ulceration along with mucopurulent conjunctivitis and dry eye 10 days after the fourth dose of intravesical Bacille Calmette-Guerin (BCG) instillation for treatment of bladder carcinoma. Slit lamp examination revealed thinning of the cornea at the base of the ulcer in both eyes. Conjunctival swab and scraping from ulcer sent for Gram and acid fast bacilli stain and culture were negative. On the basis of history, clinical examination, and laboratory investigations, we diagnosed it as bilateral immune mediated sterile corneal ulceration along with mucopurulent conjunctivitis and dry eye. He was treated with topical antibiotics, cycloplegics, cyclosporine, lubricant gel, and bandage contact lens. There was progressive stromal melting, descemetocele formation, and perforation in the inferior part of cornea in both the eyes. He was treated with pulse steroid and paramedian tarsorraphy in both eyes. The patient was subsequently lost to follow-up. We report this case to highlight this rare complication of BCG therapy, in order to improve their management protocol in patients with similar clinical profile. We could not find a similar case after thorough PubMed search.

The efficacy versus toxicity profile of combination virotherapy and TLR immunotherapy highlights the danger of administering TLR agonists to oncolytic virus-treated mice

Injection of oncolytic vesicular stomatitis virus (VSV) into established B16ova melanomas results in tumor regression, in large part by inducing innate immune reactivity against the viral infection, mediated by MyD88- and type III interferon (IFN)-, but not TLR-4-, signaling. We show here that intratumoral (IT) treatment with lipopolysaccharide (LPS), a TLR-4 agonist, significantly enhanced the local therapy induced by VSV by combining activation of different innate immune pathways. Therapy was further enhanced by co-recruiting a potent antitumor, adaptive T-cell response by using a VSV engineered to express the ovalbumin tumor-associated antigen ova, in combination with LPS. However, the combination of IT LPS with systemically delivered VSV resulted in rapid morbidity and mortality in the majority of mice. Decreasing the intravenous (IV) dose of VSV to levels at which toxicity was ameliorated did not enhance therapy compared with IT LPS alone. Toxicity of the systemic VSV + IT LPS regimen was associated with rapidly elevated levels of serum tumor necrosis factor-α (TNF-α) and interleukin (IL)-6, which neither systemic VSV, nor IT LPS, alone induced. These data show that therapy associated with direct IT injections of oncolytic viruses can be significantly enhanced by combination with agonists of innate immune activation pathways, which are not themselves activated by the virus alone. Importantly, they also highlight possible, unforeseen dangers of combination therapies in which an immunotherapy, even delivered locally at the tumor site, may systemically sensitize the patient to a cytokine shock-like response triggered by IV delivery of oncolytic virus.

Bacterial vectors for imaging and cancer gene therapy: a review

The significant burden of resistance to conventional anticancer treatments in patients with advanced disease has prompted the need to explore alternative therapeutic strategies. The challenge for oncology researchers is to identify a therapy which is selective for tumors with limited toxicity to normal tissue. Engineered bacteria have the unique potential to overcome traditional therapies' limitations by specifically targeting tumors. It has been shown that bacteria are naturally capable of homing to tumors when systemically administered resulting in high levels of replication locally, either external to (non-invasive species) or within tumor cells (pathogens). Pre-clinical and clinical investigations involving bacterial vectors require relevant means of monitoring vector trafficking and levels over time, and development of bacterial-specific real-time imaging modalities are key for successful development of clinical bacterial gene delivery. This review discusses the currently available imaging technologies and the progress to date exploiting these for monitoring of bacterial gene delivery in vivo.

[Recurrent bladder cancer after BCG instillation therapy. Local therapy options?]

Patients with a so-called BCG failure (Bacillus Calmette-Guérin) constitute an inhomogeneous group of patients. Patients with BCG recurrence or BCG refractive tumors are real BCG failures. Therapeutic options are radical cystectomy and a conservative approach, depending on the individual risk of recurrence and progression. Intravesical chemotherapy with docetaxel or gemcitabine after BCG failure shows some promise whereas second line immunotherapy, the combination of BCG and interferon (INF)-α, is an effective regimen but results need to be confirmed. Device-assisted intravesical strategies, such as mitomycin-EMDA or chemohyperthermia are candidates to keep in mind for the near future. Finally, cystectomy results in the best disease-specific survival in patients with BCG failure.

Perioperative management of nonmuscle-invasive bladder cancer

PURPOSE OF REVIEW

The management of nonmuscle-invasive bladder cancer is a challenge. Despite current guidelines, the treatment is suboptimal as illustrated by the high risk of recurrence and progression. Transurethral resection plays a pivotal role in the management of bladder cancer, but the quality varies dramatically. In this review, we discuss the latest developments that aim to improve the outcome of a transurethral resection such as photodynamic diagnosis, a second resection and adjuvant therapy.

RECENT FINDINGS

The treatment of a bladder cancer patient can be improved, for example, with a standard second resection in a subset of the patients or the use of visual enhancement techniques. There is conflicting data on the clinical value of techniques like photodynamic diagnosis, as it does not always seem to translate into a better long-term outcome. Comparison of studies is difficult because of differences in patient selection and endpoints. Better classification in (personalized) risk categories may facilitate the treatment choice and prediction of the long-term outcome.

SUMMARY

The outcome of bladder cancer patients can be improved. A good-quality transurethral resection of the bladder tumor is crucial and novel technological developments may improve the outcome, but they remain the subject of discussion.

Cancer immunotherapy comes of age

Activating the immune system for therapeutic benefit in cancer has long been a goal in immunology and oncology. After decades of disappointment, the tide has finally changed due to the success of recent proof-of-concept clinical trials. Most notable has been the ability of the anti-CTLA4 antibody, ipilimumab, to achieve a significant increase in survival for patients with metastatic melanoma, for which conventional therapies have failed. In the context of advances in the understanding of how tolerance, immunity and immunosuppression regulate antitumour immune responses together with the advent of targeted therapies, these successes suggest that active immunotherapy represents a path to obtain a durable and long-lasting response in cancer patients.

Toll-like receptor 4 activation in cancer progression and therapy

Cancer immunotherapy has been the focus of intense research since the late 19th century when Coley observed that bacterial components can contribute to cancer regression by eliciting an antitumor immune response. Successful activation and maturation of tumor-specific immune cells is now known to be mediated by bacterial endotoxin, which activates Toll-like receptor 4 (TLR4). TLR4 is expressed on a variety of immune as well as tumor cells, but its activation can have opposing effects. While TLR4 activation can promote antitumor immunity, it can also result in increased tumor growth and immunosuppression. Nevertheless, TLR4 engagement by endotoxin as well as by endogenous ligands represents notable contribution to the outcome of different cancer treatments, such as radiation or chemotherapy. Further research of the role and mechanisms of TLR4 activation in cancer may provide novel antitumor vaccine adjuvants as well as TLR4 inhibitors that could prevent inflammation-induced carcinogenesis.

Intravesical interleukin-15 gene therapy in an orthotopic bladder cancer model

Interleukin-15 (IL-15) is known to stimulate the proliferation of CD8(+) T-cells and natural killer cells, and also to help to maintain memory CD8(+) T cells, suggesting that it may be of value in cytokine treatment of bladder cancer. In this experiment, we tested the efficiency of intravesical liposomal IL-15 gene delivery and its antitumor effect in a mouse orthotopic bladder cancer model. We established an orthotopic bladder cancer model by implanting 5×10(5) MBT-2 cells into female C3H/HeN mice through the urethra. The mice received repeated intravesical gene delivery injected with liposome-mediated plasmids (5 μg) transurethrally. On day 23, the bladder weights in the group receiving medium alone, the beta-galactosidase gene delivery control group, and the IL-15 gene therapy group were 196±36 mg, 201±35 mg, and 96±29 mg, respectively (p<0.05), demonstrating the antitumor effect of intravesical IL-15 gene therapy in this model. In the bladders treated with IL-15 gene plasmid instillation, histological analysis revealed that many inflammatory cells were induced around the tumors. Immunohistochemical analysis confirmed that there was predominant infiltration of CD8(+) T cells around the tumor nest. After the intravesical IL-15 gene therapy, the growth of rechallenged subcutaneous MBT-2 cells in surviving mice was inhibited again via tumor-specific cytotoxic T lymphocytes, although newly implanted FM3A cells in the same mice were not rejected. The present findings indicate that IL-15 gene therapy may be a promising new adjuvant therapy for bladder cancer.