Antitumour immunity of Bacillus Calmette-Guerin and interferon alpha in murine bladder cancer

Recombinant BCG to Enhance Its Immunomodulatory Activities

The bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium bovis derivative that has been widely used as a live vaccine against tuberculosis for a century. In addition to its use as a tuberculosis vaccine, BCG has also been found to have utility in the prevention or treatment of unrelated diseases, including cancer. However, the protective and therapeutic efficacy of BCG against tuberculosis and other diseases is not perfect. For three decades, it has been possible to genetically modify BCG in an attempt to improve its efficacy. Various immune-modulatory molecules have been produced in recombinant BCG strains and tested for protection against tuberculosis or treatment of several cancers or inflammatory diseases. These molecules include cytokines, bacterial toxins or toxin fragments, as well as other protein and non-protein immune-modulatory molecules. The deletion of genes responsible for the immune-suppressive properties of BCG has also been explored for their effect on BCG-induced innate and adaptive immune responses. Most studies limited their investigations to the description of T cell immune responses that were modified by the genetic modifications of BCG. Some studies also reported improved protection by recombinant BCG against tuberculosis or enhanced therapeutic efficacy against various cancer forms or allergies. However, so far, these investigations have been limited to mouse models, and the prophylactic or therapeutic potential of recombinant BCG strains has not yet been illustrated in other species, including humans, with the exception of a genetically modified BCG strain that is now in late-stage clinical development as a vaccine against tuberculosis. In this review, we provide an overview of the different molecular engineering strategies adopted over the last three decades in order to enhance the immune-modulatory potential of BCG.

Indoleamine 2,3-Dioxygenase-1 Expression is Changed During Bladder Cancer Cell Invasion

The severity of the bladder carcinoma (BC) is directly linked to cell invasion and metastasis. Indoleamine 2,3-dioxygenase-1 (IDO-1) is an INF-γ-induced immunomodulating enzyme that has been linked to the cancer cell invasiveness. Because IDO1 is variable among the tumors, we analyzed its expression in the BC invasion using BC mice models and cell culture. MB49 cells were orthotopically or ectopically inoculated in C57Bl6 mice to evaluate IDO1 by immunohistochemistry. For in vitro experiments, expression of IDO1 and INF-γ was evaluated in grade-1 (RT4) and in grade-3 (T24) BC cell lines. Invading and non-invading T24 cells were separated using the Matrigel/Transwell system, of which total RNA was extracted immediately or after 2 weeks of subculture. Finally, IDO1 was silenced in T24 cells to verify its role on cell invasiveness. In both animal models, IDO1 was differentially expressed between non-invading and invading cells. In cell culture, T24 cells expressed more IDO1 than RT4 cells, independently of the INF-γ expression. IDO1 was differentially expressed between non-invading and invading T24 cells, a difference that was lost by long-time subculture. IDO1 silencing resulted in diminished cell invasiveness. In conclusion, IDO1 expression is changed during bladder carcinoma invasion, playing an important role in this process.

Intravesical High Dose BCG Tokyo and Low Dose BCG Tokyo with GMCSF+IFN α Induce Systemic Immunity in a Murine Orthotopic Bladder Cancer Model

This study evaluates a short therapy schedule for bladder cancer using BCG Tokyo. BCG Tokyo was evaluated in vitro using bone marrow derived dendritic cells, neutrophils, RAW macrophages and the murine bladder cancer cell line, MB49PSA, and compared to other BCG strains. BCG Tokyo > BCG TICE at inducing cytokine production. In vivo, high dose (1 × 10⁷ colony forming units (cfu)) and low dose (1 × 10⁶ cfu) BCG Tokyo with and without cytokine genes (GMCSF + IFNα) were evaluated in C57BL/6J mice (n = 12–16 per group) with orthotopically implanted MB49PSA cells. Mice were treated with four instillations of cytokine gene therapy and BCG therapy. Both high dose BCG alone and low dose BCG combined with cytokine gene therapy were similarly effective. In the second part the responsive groups, mice (n = 27) were monitored by urinary PSA analysis for a further 7 weeks after therapy cessation. More mice were cured at day 84 than at day 42 confirming activation of the immune system. Cured mice resisted the re-challenge with subcutaneous tumors unlike naïve, age matched mice. Antigen specific T cells recognizing BCG, HY and PSA were identified. Thus, fewer intravesical instillations, with high dose BCG Tokyo or low dose BCG Tokyo with GMCSF + IFNα gene therapy, can induce effective systemic immunity.

MyD88-dependent BCG immunotherapy reduces tumor and regulates tumor microenvironment in bladder cancer murine model

Bacillus Calmette-Guerin (BCG) is the only FDA approved first line therapy for patients with nonmuscle invasive bladder cancer. The purpose of this study is to better understand the role of innate immune pathways involved in BCG immunotherapy against murine bladder tumor. We first characterized the immunological profile induced by the MB49 mouse urothelial carcinoma cell line. MB49 cells were not able to activate an inflammatory response (TNF-α, IL-6, CXCL-10 or IFN-β) after the stimulus with different agonists or BCG infection, unlike macrophages. Although MB49 cells are not able to induce an efficient immune response, BCG treatment could activate other cells in the tumor microenvironment (TME). We evaluated BCG intratumoral treatment in animals deficient for different innate immune molecules (STING-/-, cGAS-/-, TLR2-/-, TLR3-/-, TLR4-/-, TLR7-/-, TLR9-/-, TLR3/7/9-/-, MyD88-/-, IL-1R-/-, Caspase1/11-/-, Gasdermin-D-/- and IFNAR-/-) using the MB49 subcutaneous mouse model. Only MyD88-/- partially responded to BCG treatment compared to wild type (WT) mice, suggesting a role played by this adaptor molecule. Additionally, BCG intratumoral treatment regulates cellular infiltrate in TME with an increase of inflammatory macrophages, neutrophils and CD8+ T lymphocytes, suggesting an immune response activation that favors tumor remission in WT mice but not in MyD88-/-. The experiments using MB49 cells infected with BCG and co-cultured with macrophages also demonstrated that MyD88 is essential for an efficient immune response. Our data suggests that BCG immunotherapy depends partially on the MyD88-related innate immune pathway.

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.

Mitigation of Radiation-Induced Epithelial Damage by the TLR5 Agonist Entolimod in a Mouse Model of Fractionated Head and Neck Irradiation

Radiation treatment of head and neck cancer frequently causes severe collateral damage to normal tissues including mouth mucosa, salivary glands and skin. This toxicity limits the radiation dose that can be delivered and affects the patient's quality of life. Previous studies in mice and nonhuman primates showed that entolimod, a toll-like receptor 5 (TLR5) agonist derived from bacterial flagellin, effectively reduced radiation damage to hematopoietic and gastrointestinal tissues in both total-body and local irradiation scenarios, with no protection of tumors. Here, using a mouse model, we analyzed the efficacy of entolimod administered before or after irradiation in reducing damage to normal tissues. Animals received local fractionated radiation to the head and neck area, thus modeling radiotherapy of head and neck cancer. Tissue damage was evaluated through histomorphological examination of samples collected at different time points up to four weeks, mice were exposed locally to five daily fractions of 5, 6 or 7 Gy. A semiquantitative scoring system was used to assess the severity of observed pathomorphological changes. In this model, radiation damage was most severe in the lips, tongue and skin, moderate in the upper esophagus and minor in salivary glands. The kinetics of injury appearance and recovery of normal morphology varied among tissues, with maximal damage to the tongue, esophagus and salivary glands developing at earlier times (days 8-11 postirradiation) relative to that of lip and skin mucosa (days 11-15 postirradiation). While both tested regimens of entolimod significantly reduced the extent of radiation damage and accelerated restoration of normal structure in all tissues analyzed, administration of entolimod 1 h after each irradiation was more effective than treatment 30 min before irradiation. These results support the potential clinical use of entolimod as an adjuvant for improving the therapeutic index of head and neck cancer radiotherapy by reducing the radiation toxicity in normal tissues.

Subcutaneous Injections of the Mannose-Sensitive Hemagglutination Pilus Strain of Pseudomonas aeruginosa Stimulate Host Immunity, Reduce Bladder Cancer Size and Improve Tumor Survival in Mice

We wished to evaluate the effects of Pseudomonas aeruginosa (mannose-sensitive hemagglutination pilus strain, PA-MSHA) as an immunostimulating and anti-tumor agent for treatment of bladder cancer. Immunostimulating effects were assessed by the in vitro proliferation assay of murine splenic lymphocytes. Anti-tumor effects were studied in a subcutaneous tumor model established in female C57BL/6 mice using the MB49 bladder cell line. These mice received subcutaneous injections of normal saline (control group) or PA-MSHA (high, medium, or low dose, respectively, 1.6-2.0 × 10(9), 3.2- .0 × 10(8), 6.4-8.0 × 10(7) CFU/ml) twice a week for 3 weeks. Mice survival, tumor volume, vascular endothelial growth factor (VEGF) expression, microvessel density (MVD), serum levels of TNF-α and IFN-γ, and blood CD4(+) /CD8(+) counts were the study outcomes. We observed that PA-MSHA promoted the growth of splenic lymphocytes in vitro. In the murine tumor model, PA-MSHA prolonged mice survival and reduced tumor growth. Furthermore, VEGF and MVD were also diminished by PA-MSHA. Mice that received high and medium dose of PA-MSHA had significantly higher serum levels of IFN-γ and TNF-α (days 21 and 28), and higher levels of CD4(+) /CD8(+) cells (days 21 and 28). In conclusion, PA-MSHA exerts beneficial effects on increasing proliferation of murine splenic lymphocytes in vitro and inhibits the growth of bladder tumor in a murine model. Therefore, PA-MSHA may be useful an immunostimulating and anti-tumor agent for bladder cancer therapy.

Systemic Immunotherapy of Non-Muscle Invasive Mouse Bladder Cancer with Avelumab, an Anti-PD-L1 Immune Checkpoint Inhibitor

Bacillus Calmette-Guerin (BCG) is the standard of care for intravesical therapy for carcinoma in situ and non-muscle invasive, nonmetastatic human urothelial carcinoma. Although the responsiveness to this immunotherapeutic is believed to be linked with (i) a high number of somatic mutations and (ii) a large number of tumor-infiltrating lymphocytes, recent findings of the roles that inhibitory immune receptors and their ligands play in tumor evasion may provide insights into the limitations of the effectiveness of BCG and offer new targets for immune-based therapy. In this study, an aggressive, bioluminescent orthotopic bladder cancer model, MB49 tumor cells transfected with luciferase (MB49(luc)), was used to study the antitumor effects of avelumab, an antibody to PD-L1. MB49(luc) murine tumor cells form multifocal tumors on the mucosal wall of the bladder reminiscent of non-muscle invasive, nonmetastatic urothelial carcinomas. MB49(luc) bladder tumors are highly positive for the expression of PD-L1, and avelumab administration induced significant (P < 0.05) antitumor effects. These antitumor effects were more dependent on the presence of CD4 than CD8 T cells, as determined by in vivo immune cell depletions. The findings suggest that in this bladder tumor model, interruption of the immune-suppressive PD-1/PD-L1 complex releases a local adaptive immune response that, in turn, reduces tumor growth. This bladder tumor model can be used to further identify host antitumor immune mechanisms and evaluate combinations of immune-based therapies for carcinoma in situ and non-muscle invasive, nonmetastatic urothelial carcinoma, to provide the rationale for subsequent clinical studies. Cancer Immunol Res; 4(5); 452-62. ©2016 AACR.

Immunotherapy for urothelial cancer: from BCG to checkpoint inhibitors and beyond

Since its introduction almost 40 years ago, intravesical BCG for non-muscle invasive bladder cancer remains one of the most successful cancer immunotherapies. However, up to 40% of patients will progress after BCG therapy and develop invasive bladder cancer. Despite its extensive clinical use, we are only beginning to understand how BCG works. Here we review preclinical and clinical data that implicate BCG-induced Th1 and cytotoxic cellular immune responses in cancer regression. We propose that future immunotherapies should aim to augment Th1 and/or cellular responses in those that fail BCG therapy. We review clinical trials of immunotherapy in bladder cancer with a focus on the promising role of checkpoint blockade inhibitors that target the programmed cell death 1/programmed death-ligand 1 (PD-L1) axis and/or cytotoxic T lymphocyte antigen 4.

From infection to immunotherapy: host immune responses to bacteria at the bladder mucosa

The pathogenesis of urinary tract infection and mechanisms of the protective effect of Bacillus Calmette-Guerin (BCG) therapy for bladder cancer highlight the importance of studying the bladder as a unique mucosal surface. Innate responses to bacteria are reviewed, and although our collective knowledge remains incomplete, we discuss how adaptive immunity may be generated following bacterial challenge in the bladder microenvironment. Interestingly, the widely held belief that the bladder is sterile has been challenged recently, indicating the need for further study of the impact of commensal microorganisms on the immune response to uropathogen infection or intentional instillation of BCG. This review addresses the aspects of bladder biology that have been well explored and defines what still must be discovered about the immunobiology of this understudied organ.

Bladder Cancer Immunotherapy: BCG and Beyond

Mycobacterium bovis bacillus Calmette-Guérin (BCG) has become the predominant conservative treatment for nonmuscle invasive bladder cancer. Its mechanism of action continues to be defined but has been shown to involve a T helper type 1 (Th1) immunomodulatory response. While BCG treatment is the current standard of care, a significant proportion of patients fails or do not tolerate treatment. Therefore, many efforts have been made to identify other intravesical and immunomodulating therapeutics to use alone or in conjunction with BCG. This paper reviews the progress of basic science and clinical experience with several immunotherapeutic agents including IFN-α, IL-2, IL-12, and IL-10.

Additively enhanced antiproliferative effect of interferon combined with proanthocyanidin on bladder cancer cells

Although interferon (IFN) has been often used as immunotherapy for bladder cancer, its efficacy is rather unsatisfactory, demanding further improvement. Combination therapy is one of viable options, and grape seed proanthocyanidin (GSP) could be such an agent to be used with IFN because it has been shown to have anticancer activity. We thus investigated whether combination of IFN and GSP might enhance the overall antiproliferative effect on bladder cancer cells in vitro. Human bladder cancer T24 cells were employed and treated with the varying concentrations of recombinant IFN-α_2b (0-100,000 IU/ml), GSP (0-100 μg/ml), or their combinations. IFN-α_2b alone led to a ~50% growth reduction at 20,000 (20K) IU/ml, which further declined to ~67% at ≥50K IU/ml. Similarly, GSP alone induced a ~35% and ~100% growth reduction at 25 and ≥50 μg/ml, respectively. When IFN-α_2b and GSP were then combined, combination of 50K IU/ml IFN-α_2b and 25 μg/ml GSP resulted in a drastic >95% growth reduction. Cell cycle analysis indicated that such an enhanced growth inhibition was accompanied by a G₁ cell cycle arrest. This was further confirmed by Western blot analysis revealing that expressions of G₁-specific cell cycle regulators (CDK2, CDK4, cyclin E and p27/Kip1) were distinctly modulated with such IFN-α_2b/GSP treatment. Therefore, these findings support the notion that combination of IFN-α_2b and GSP is capable of additively enhancing antiproliferative effect on T24 cells with a G₁ cell cycle arrest, implying an adjuvant therapeutic modality for superficial bladder cancer.

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.

Intravesical immunotherapy of superficial bladder cancer with chitosan/interleukin-12

Intravesical BCG has been used successfully to treat superficial bladder cancer for three decades. However, 20% to 30% of patients will fail initial BCG therapy and 30% to 50% of patients will develop recurrent tumors within 5 years. Alternative or complementary strategies for the management of superficial bladder cancer are needed. Interleukin-12 (IL-12) is a potent T(H)1 cytokine with robust antitumor activity and the ability to potentiate immunologic memory. Unfortunately, intravesical IL-12 did not show antitumor efficacy in a recent clinical study of patients with recurrent superficial bladder cancer. We hypothesized that coformulation of IL-12 with chitosan, a biocompatible, mucoadhesive polysaccharide, could improve intravesical IL-12 delivery and provide an effective and durable alternative for the treatment of superficial bladder cancer. In antitumor studies, 88% to 100% of mice bearing orthotopic bladder tumors were cured after four intravesical treatments with chitosan/IL-12. In contrast, only 38% to 60% of mice treated with IL-12 alone and 0% treated with BCG were cured. Antitumor responses following chitosan/IL-12 treatments were durable and provided complete protection from intravesical tumor rechallenge. Urinary cytokine analysis showed that chitosan/IL-12 induced multiple T(H)1 cytokines at levels significantly higher than either IL-12 alone or BCG. Immunohistochemistry revealed moderate to intense tumor infiltration by T cells and macrophages following chitosan/IL-12 treatments. Bladder submucosa from cured mice contained residual populations of immune cells that returned to baseline levels after several months. Intravesical chitosan/IL-12 is a well-tolerated, effective immunotherapy that deserves further consideration for testing in humans for the management of superficial bladder cancer.

Cytokine gene expression in a mouse model: the first instillations with viable bacillus Calmette-Guerin determine the succeeding Th1 response

PURPOSE

Bacillus Calmette-Guerin (BCG) therapy for superficial bladder cancer is immune dependent and activation of a Th1 immune response is probably required for clinical efficacy. Given the empirical approach to improving BCG therapy we investigated in a mouse model the consequences of modifications in BCG therapy with regard to Th1 and Th2 cytokine responses in the bladder. These studies may provide a rationale for possible modifications of the established clinical treatment protocol.

MATERIALS AND METHODS

The dynamics of Th1 (interferon-gamma, interleukin [IL]-2, IL-12p40 and tumor necrosis factor-alpha) and Th2 (IL-10 and IL-4) cytokine responses during and after 6 once weekly intravesical BCG instillations in mice was determined by a semiquantitative reverse transcriptase-polymerase chain reaction based method.

RESULTS

During 6 weekly BCG instillations a dose and time dependent induction of the various Th1 as well as Th2 cytokines was observed. The response pattern was comparable to urinary cytokine induction patterns in patients. Electrocauterization prior to BCG instillations led to lower and more variable levels of cytokine polymerase chain reaction products compared with noncauterization. Lowering the dose of BCG seemed to affect the Th1 cytokine response most, whereas the Th2 response was less influenced by dilution of the BCG preparation. Six instillations with nonviable BCG induced Th2 but failed to induce Th1 cytokines, which may explain the necessity of BCG viability for antitumor activity. However, when mice were first treated 3 times with viable BCG and subsequently received 3 instillations with killed BCG, the Th1 and Th2 cytokine pattern was comparable to the standard 6-week regimen with viable BCG.

CONCLUSIONS

The model seems an appropriate one in which to investigate changes in Th1 and Th2 cytokine gene expression levels in bladders resulting from modifications in intravesical BCG treatment. It was possible to induce a local Th1 cytokine response with nonviable BCG provided that local sensitization to BCG antigens had occurred during preceding instillations with a viable BCG preparation. Whether such an approach could decrease BCG therapy toxicity, while maintaining antitumor efficacy, remains to be further investigated in patients.

A chimeric multi-human epidermal growth factor receptor-2 B cell epitope peptide vaccine mediates superior antitumor responses

Immunotherapeutic approaches to cancer should focus on novel undertakings that modulate immune responses by synergistic enhancement of antitumor immunological parameters. Cancer vaccines should preferably be composed of multiple defined tumor Ag-specific B and T cell epitopes. To develop a multiepitope vaccine, 12 high ranking B cell epitopes were identified from the extracellular domain of the human epidermal growth factor receptor-2 (HER-2) oncoprotein by computer-aided analysis. Four novel HER-2 B cell epitopes were synthesized as chimeras with a promiscuous T cell epitope (aa 288-302) from the measles virus fusion protein (MVF). Two chimeric peptide vaccines, MVF HER-2(316-339) and MVF HER-2(485-503) induced high levels of Abs in outbred rabbits, which inhibited tumor cell growth. In addition, Abs induced by a combination of two vaccines, MVF HER-2(316-339) and MVF HER-2(628-647) down-modulated receptor expression and activated IFN-gamma release better than the individual vaccines. Furthermore, this multiepitope vaccine in combination with IL-12 caused a significant reduction (p = 0.004) in the number of pulmonary metastases induced by challenge with syngeneic tumor cells overexpressing HER-2. Peptide Abs targeting specific sites in the extracellular domain may be used for exploring the oncoprotein's functions. The multiepitope vaccine may have potential application in the treatment of HER-2-associated cancers.

A randomized comparative dose-ranging study of interferon-alpha and mitomycin-C as an internal control in primary or recurrent superficial transitional cell carcinoma of the bladder

OBJECTIVE

To compare, in a phase II study, the activity and toxicity of three dose levels of interferon-alpha, and of mitomycin-C given intravesically (as an internal control to validate the results), the primary objective being to investigate the percentage of complete responses (complete disappearance of a marker lesion) induced by the three interferon-alpha dose levels on a marker lesion; a secondary objective was to compare the interferon-alpha doses for toxicity.

PATIENTS AND METHODS

In all, 115 patients were enrolled, with the inclusion criteria being multiple grade 1 or 2, stage Ta or T1, primary or recurrent transitional cell carcinoma of the bladder. Interferon-alpha (30, 50 and 80 MU) and mitomycin-C (40 mg) intravesical treatments were given as follows. Patients randomized to one of three interferon-alpha dose levels were treated weekly for 12 weeks. However, in week 9 (first cystoscopy after baseline) interferon-alpha treatment was stopped if there was a complete response or disease progression. Patients randomized to mitomycin-C were treated weekly for 8 weeks only and in week 9 underwent follow-up cystoscopy.

RESULTS

Interferon-alpha at doses of 30, 50 and 80 MU gave response rates at 13 weeks of 19%, 33% and 41%, respectively. Although the response rates were higher for 50 and 80 MU than for 30 MU, the differences were not statistically significant. All three interferon-alpha groups had significantly lower response rates than the internal control, mitomycin-C (72%). The safety analysis showed that most of the adverse events were of mild to moderate severity. Adverse events were experienced by 37%, 37% and 48% of patients receiving 30, 50 and 80 MU interferon-alpha, respectively, and by 55% of patients receiving mitomycin-C. The corresponding rates for severe adverse events related to treatment were 9% for interferon-alpha and 10% for mitomycin-C.

CONCLUSION

Ablative therapy with interferon-alpha was less effective than mitomycin-C in patients with superficial bladder cancer. Both drugs were well tolerated, although interferon-alpha appeared to have a slightly better overall safety profile.

Model of differential susceptibility to mucosal Burkholderia pseudomallei infection

Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease with protean clinical manifestations. The major route of infection is thought to be through subcutaneous inoculation of contaminated soil and water, although ingestion and inhalation of contaminated aerosols are also possible. This study examines infection through the intranasal route in a murine model to mimic infection through inhalation. Two strains of mice, C57BL/6 and BALB/c, exhibit differential susceptibilities to the infection, with the C57BL/6 mice being considerably more resistant. To examine host factors that could contribute to this difference, bacterial loads and cytokine profiles in the two strains of mice were compared. We found that infected BALB/c mice exhibited higher bacterial loads in the lung and spleen and that they produced significantly higher levels of gamma interferon (IFN-gamma) in the serum than C57BL/6 mice. Although tumor necrosis factor alpha and interleukin-1 could be detected in the nasal washes and sera of both strains of mice, the production in serum was transient and much lower than that of IFN-gamma. C57BL/6 mice also exhibited memory responses to bacteria upon reinfection, with the production of serum immunoglobulin G (IgG) and mucosal IgA antibodies. Thus, it is possible that the production of systemic and mucosal antibodies is important for protection against disease in C57BL/6 mice.

Chemopreventive effect of Lactobacillus rhamnosus on growth of a subcutaneously implanted bladder cancer cell line in the mouse

Lactic acid bacteria are known to have beneficial effects on the host, such as preventing carcinogenesis. The present study was designed to evaluate the chemopreventive effects of Lactobacillus rhamnosus strain GG (LGG) in suppressing bladder cancer formation in a murine subcutaneous model of bladder cancer involving the inoculation of MB49 cells in C57B / L6 mice. After tumor implantation, one group of mice (n = 8) was fed LGG immediately. The remaining mice that had tumors between 0.03 - 0.1 cm(3) were divided into two groups: those fed LGG after 7 days (n = 7) and those fed saline (n = 7). A second group of mice without any inoculation of MB49 cells was fed either LGG (n = 10) or saline (n = 10) and served as non-tumor-bearing controls. LGG was administered orally at 1.6 x 10(8) colony-forming units daily. Mice fed LGG immediately after tumor cell implantation formed smaller tumors and some did not develop tumors (2 out of 8 mice), when the tumor burden was small. The level of spleen CD3, CD4 and CD8a T lymphocytes, as well as natural killer cells in mice fed immediately with LGG was also higher than that in control tumor-bearing mice. There was an increase in lymphocytes and granulocytes in tumor sections, especially from the immediately fed group as compared to the controls. Our results suggest that oral consumption of LGG may prevent tumor growth via modulation of the immune system. The potential of LGG as an adjunct therapy in the treatment of bladder cancer could be further explored.

Immunomodulating activity of mycobacterial heat shock protein 65 in tumor cells

In recent years, heat shock proteins have been shown to be effective in enhancing the immunogenicity of tumors. In this study, we examined the effect of mycobacterial hsp65 gene transfection in a non-immunogenic and aggressive tumor cell-line in order to understand the factors that could contribute to the increase in immunogenicity mediated by Hsp65. The transfected cells were found to have indeed lost their tumorigenenicity and increased their immunogenicity. Tumor-specific cytotoxic T cells were present only in mice immunized with the Hsp65-expressing cells. Furthermore, endogenous Hsp70 was significantly increased in irradiated Hsp65-expressing cells and recombinant Hsp65 protein was able to stimulate the mRNA expression of various T helper 1 (Th1) and pro-inflammatory cytokines in splenocyte cultures, as well as a modest expansion of CD4 T cells. These results provide further evidence of the immunomodulating properties of Hsp65, which could be exploited for the treatment of cancer.

Recombinant bacille Calmette-Guérin (BCG) expressing human interferon-alpha 2B demonstrates enhanced immunogenicity

To increase its immunostimulatory properties, BCG was genetically engineered to secrete recombinant human interferon-alpha 2B (rhIFN-alpha) under control of the mycobacterial heat shock protein (hsp)60 promoter and the alpha antigen signal sequence. Expression of rhIFN-alpha was readily detectable by ELISA and on Western blotting. When compared with control BCG, rhIFN-alpha BCG was substantially more active in inducing the production of IFN-gamma and IFN-inducible protein 10 (IP-10) from human peripheral blood mononuclear cells, while IL-10 production was correspondingly decreased. These effects were reversible upon antibody neutralization of rhIFN-alpha. Among 10 patients tested, rhIFN-alpha BCG enhanced IFN-gamma production in all patients ranging from 1.4- to 23.7-fold with a general trend toward greatest enhancement among those with weakest baseline responses to control BCG. Correspondingly, rhIFN-alpha BCG decreased IL-10 production in all patients by 1.2-4.8-fold. The onset of IFN-gamma production induced by rhIFN-alpha BCG was also more rapid, occurring within 4 h after stimulation versus > 24 h with wild-type BCG. The observation that the maximum IFN-gamma induction depends on the simultaneous presence of both IFN-alpha and BCG highlights the advantages of rhIFN-alpha BCG. Taken together, these immunostimulatory properties of rhIFN-alpha BCG suggest that it may be a superior agent for immunotherapeutic protocols involving live BCG in humans.