Bacillus Calmette-Guérin plus interleukin-2 and/or granulocyte/macrophage-colony-stimulating factor enhances immunocompetent cell production of interferon-gamma, which inhibits B16F10 melanoma cell growth in vitro

Thirty years of recombinant BCG: new trends for a centenary vaccine

Introduction: Global perception of the potential for Bacille Calmette-Guérin (BCG), and consequently recombinant BCG (rBCG), in a variety of prophylactic and therapeutic applications has been increasing. A century of information on BCG, and three decades of experience with rBCG, has generated solid knowledge in this field.Area covered: Here, we review the current state of knowledge of BCG and rBCG development. Molecular tools have facilitated the expression of a variety of molecules in BCG, with the aim of improving its efficacy as a tuberculosis vaccine, generating polyvalent vaccines against other pathogens, including viruses, bacteria, and parasites, and developing immunotherapy approaches against noninvasive bladder cancer. BCG's recently appraised heterologous effects and prospects for expanding its application to other diseases are also addressed.Expert opinion: There are high expectations for new tuberculosis vaccines currently undergoing advanced clinical trials, which could change the prospects of the field. Systems biology could reveal effective biomarkers of protection, which would greatly support vaccine development. The development of appropriate large-scale production processes would further support implementation of new vaccines and rBCG products. The next few years should consolidate the broader applications of BCG and produce insights into improvements using the recombinant BCG technology.

Mycobacterium bovis BCG in metastatic melanoma therapy

Melanoma is the most aggressive form of skin cancer, with a high mortality rate and with 96,480 new cases expected in 2019 in the USS. BRAF^V600E, the most common driver mutation, is found in around 50% of melanomas, contributing to tumor growth, angiogenesis, and metastatic progression. Dacarbazine (DTIC), an alkylate agent, was the first chemotherapeutic agent approved by the US Food and Drug Administration (FDA) used as a standard treatment. Since then, immunotherapies have been approved for metastatic melanoma (MM) including ipilimumab and pembrolizumab checkpoint inhibitors that help decrease the risk of progression. Moreover, Mycobacterium bovis Bacillus Calmette-Guerin (BCG) serves as an adjuvant therapy that induces the recruitment of natural killer NK, CD4⁺, and CD8⁺ T cells and contributes to antitumor immunity. BCG can be administered in combination with chemotherapeutic and immunotherapeutic agents and can be genetically manipulated to produce recombinant BCG (rBCG) strains that express heterologous proteins or overexpress immunogenic proteins, increasing the immune response and improving patient survival. In this review, we highlight several studies utilizing rBCG immunotherapy for MM in combination with other therapeutic agents.

Sequential administration of GM-CSF and IL-2 surface-modified MB49 cells vaccines against the metastatic bladder cancer

OBJECTIVES

Many strategies are pursued to enhance tumor vaccine immune response, including the utilization of cytokines. We have developed a novel protein-anchor technology to immobilize cytokines on tumor cell surface. Here we reported the preparation of tumor cell vaccines by immobilizing GM-CSF or IL-2 on MB49 bladder cancer cells and evaluated their antitumor efficacy (administrated alone or sequentially) in a metastatic mouse model.

MATERIALS AND METHODS

SA-mGM-CSF or SA-hIL-2 surface-modified MB49 cells were prepared as vaccine. Mice were treated with MB49 cell vaccines (administrated alone or sequentially). Survival time, tumor growth, flow cytometry, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and cytotoxic T lymphocytes (CTL) assay were used to evaluate the antitumor efficiency of the vaccines in the pulmonary metastatic model of bladder cancer.

RESULTS

GM-CSF vaccine induced more mature dendritic cells in the mice spleen. Combination with subsequent IL-2 vaccine significantly increased CD4(+), CD8(+), and IFN-γ(+)CD8(+) T but not CD4(+)Foxp3(+) T cell population and induced the highest production of IFN-γ, IL-12, but not IL-10. Furthermore, the splenocytes from the sequentially combined vaccines group showed the most potent cytotoxicity on MB49 cells. Finally, the sequentially combined vaccines evidently extended the survival time of mice (the median survival time of PBS, ethanol-fixed, anchored GM-CSF, anchored IL-2, and anchored GM-CSF + anchored IL-2 groups were 34, 37, 45, 47, and 59 days, respectively) and effectively protected the mice against a second MB49 cells but not RM-1 cells challenge.

CONCLUSIONS

This study demonstrated that sequential administration of GM-CSF and IL-2 surface-modified MB49 cells vaccines could effectively induce specific antitumor immune response.

Sensitivity of morphological change of Vero cells exposed to lipophilic compounds and its mechanism

To find a sensitive cytotoxic response to reflect the toxicity of trace organic pollutants, the sensitivity and reliability of morphological change and proliferation inhibition of Vero cells exposed to lipophilic compounds and the leachate from products related to drinking water (PRDW) were compared, and the mechanism of the morphological change in Vero cells was studied. Results showed the proportion of morphologically changed cells increased with increasing 2,4,6-trichlorophenol (TCP)/perfluorooctane sulfonate (PFOS) concentration. However, at low TCP concentrations, inhibition of cell proliferation did not correlate to TCP concentration. After exposure to the leachate from PRDW extracted at different temperatures, the percentage of morphologically changed cells increased with extracting temperature, but the inhibition of cell proliferation failed to reflect the correlation to extracting temperature. These imply cell morphological change is a more sensitive and reliable method to reflect toxicity of trace organic pollutants than proliferation inhibition. Flow cytometry analysis indicated cell membrane damage was an early and sensitive cytotoxic response comparing with necrosis, resulting in cell morphological change, which may be due to the interference of lipophilic compounds. Lipophilic compound accumulated in cell membrane to interfere the assembly process of membrane protein and phospholipid.

Interleukin 10 induced augmentation of delayed-type hypersensitivity (DTH) enhances Mycobacterium bovis bacillus Calmette-Guérin (BCG) mediated antitumour activity

Intravesical BCG therapy is effective in the treatment of superficial bladder cancer. Both clinical and experimental results suggest a role for cytokines and delayed-type hypersensitivity (DTH) in BCG-induced antitumour immunity. We characterized the modulatory effects of BCG on bladder cytokine expression and determined the relationship between DTH and BCG antitumour activity. The bladders of mice were instilled with BCG through a catheter. Bladder tissue RNA and urine were collected for evaluation of cytokine expression using reverse transcriptase-polymerase chain reaction (RT-PCR) and/or ELISA. IFN-gamma and TNF-alpha, the two major cytokines associated with DTH, were efficiently induced by BCG. IL10, an important down-regulator of DTH, was also induced by BCG. Constitutive levels of IL4 and IL5 were observed, but neither IL4 nor IL5 were modulated by BCG. Similar results were observed in the kinetic analysis of urinary cytokines in patients after intravesical BCG therapy. Production of Th1 (T helper type 1) cytokines (IFN-gamma, IL2 and IL12) preceded that of the Th2 (T helper type 2) cytokine IL10. A tendency toward higher ratios of IFN-gamma versus IL10 for BCG responders also was observed. In animal studies the absence of IL10 abrogated either by antibody inhibition or the use of genetically modified, IL10 deficient (IL10-/-) mice resulted in enhanced DTH responses. Under conditions of enhanced DTH, a significant enhancement in antitumour activity was observed. These data demonstrate that DTH and its associated mononuclear infiltration and cytokine production are important to the antitumour activity of intravesical BCG therapy, and suggest that effects to diminish IL10 production may have therapeutic value.

Role of Th1 and Th2 cytokines in BCG-induced IFN-gamma production: cytokine promotion and simulation of BCG effect

Induction of a T-helper-type 1 (Th1) immune response is indispensable for successful treatment of superficial bladder cancer with BCG. In this study possible involvement of various cytokines in BCG action as well as their potential roles in enhancing and mimicking BCG effect were explored. In immunocompetent cell cultures, IFN-gamma, a major Th1 cytokine, appears to be a late responsive cytokine to BCG stimulation. Its induction requires involvement of various endogenously produced Th1 and Th2 cytokines. Functional abolishment of any one of these cytokines (IL-2, IL-6, IL-12, IL-18, GMCSF, TNF-alpha, or IFN-alpha, except IL-10) by neutralizing antibodies leads to reduced IFN-gamma production (19-82% inhibition in mouse and 44-77% inhibition in human systems, respectively). In mice cytokines IL-2, IL-12, IL-18, and GMCSF are observed to synergize with BCG for IFN-gamma production, whereas in human cytokines IL-2, IL-12, TNF-alpha, and IFN-alpha exhibit similar synergistic effects. Rational combinations of these Th1-stimulating cytokines (IL-12 plus IL-18 in mice and IL-2 plus IL-12 in humans, respectively) dramatically up-regulate IFN-gamma production that is incomparably superior to BCG for induction of this cytokine. These results suggest that combined Th1-stimulating cytokines and combinations of BCG plus selected Th1-stimulating cytokines are rational candidates for further study in the treatment of bladder cancer patients.

Live bacteria as the basis for immunotherapies against cancer

For more than a century, bacteria and bacterial products have been used for the treatment of cancer. Starting from the practical observation of tumor regression in individuals with concomitant bacterial infection, the field has evolved into some standard clinical practices, such as the use of BCG for the treatment of superficial bladder cancer. However, in the last few years, new applications have started to emerge that may profoundly change the perspective of the field. BCG can be engineered to express cytokines to improve its efficacy. Bacteria such as Salmonella and Listeria can be attenuated by genetically-defined mutations and provide effective vehicles for DNA vaccines encoding tumor-associated antigens. Salmonella and nonpathogenic strains of Clostridium can selectively accumulate in tumors in vivo, providing attractive delivery systems to target immunomodulatory molecules and therapeutic agents to the tumor site. Many of these new developments have been attempted for prophylactic or therapeutic vaccination in several different experimental models of cancer and in many cases, results from clinical trials are now emerging. There is still some way to go before achieving products that could be in routine use, but the field has great promise for the development of more effective immunotherapies for several different cancers. In this paper, we will review the current state of such applications and highlight some of the directions that the field may take.

Inverse association between melanoma and previous vaccinations against tuberculosis and smallpox: results of the FEBIM study

Various forms of immunotherapy utilizing bacille Calmette-Guérin vaccine or vaccinia vaccine have been evaluated in clinical trials on melanoma patients. The effect of the "natural" application of these vaccinations, administered to provide protection against tuberculosis and smallpox, has, however, never been studied in epidemiologic investigations on risk factors for melanoma. In a case-control study comprising 11 institutions in seven countries we recruited 603 incident melanoma cases and 627 population controls frequency matched to the cases with respect to sex, age, and ethnic origin within each center to assess this relationship to obtain insights into the prevention of melanoma. Exposure information, incorporating also detailed ascertainment of potential confounding variables, was obtained in standardized personal interviews at the study subject's home. We found an inverse association between melanoma risk and previous bacille Calmette-Guérin vaccine/vaccinia vaccination depicted by an adjusted odds ratio of 0.44 (95% confidence interval: 0.26-0.72) for those vaccinated against tuberculosis and smallpox compared with subjects without a positive history of either vaccination. A variety of subgroup analyses showing a consistent pattern of results make it unlikely that the observed inverse association is a spurious finding. We conclude that bacille Calmette-Guérin vaccination and vaccinia vaccination may lower melanoma risk. Current immunologic theory of melanoma development provides a sound basis for understanding the biologic plausibility of the findings that have to be confirmed in future studies.

In vitro anti-tumour activity of alpha-galactosylceramide-stimulated human invariant Valpha24+NKT cells against melanoma

alpha-galactosylceramide (KRN 7000, alpha-GalCer) has shown potent in vivo anti-tumour activity in mice, including against melanoma and the highly specific effect of inducing proliferation and activation of human Valpha24+NKT-cells. We hypothesized that human Valpha24+NKT-cells activated by alpha-GalCer might exhibit anti-tumour activity against human melanoma. To investigate this, Valpha24+NKT-cells were generated from the peripheral blood of patients with melanoma after stimulation with alpha-GalCer pulsed monocyte-derived dendritic cells (Mo-DCs). Valpha24+NKT-cells did not exhibit cytolytic activity against the primary autologous or allogeneic melanoma cell lines tested. However, proliferation of the melanoma cell lines was markedly suppressed by co-culture with activated Valpha24+NKT-cells (mean +/- SD inhibition of proliferation 63.9 +/- 1.3%). Culture supernatants of activated Valpha24+NKT-cell cultures stimulated with alpha-GalCer pulsed Mo-DCs exhibited similar antiproliferative activities against melanoma cells, indicating that the majority of the inhibitory effects were due to soluble mediators rather than direct cell-to-cell interactions. This effect was predominantly due to release of IFN-gamma, and to a lesser extent IL-12. Other cytokines, including IL-4 and IL-10, were released but these cytokines had less antiproliferative effects. These in vitro results show that Valpha24+NKT-cells stimulated by alpha-GalCer-pulsed Mo-DCs have anti-tumour activities against human melanoma through antiproliferative effects exerted by soluble mediators rather than cytolytic effects as observed against some other tumours. Induction of local cytokine release by activated Valpha24+NKT-cells may contribute to clinical anti-tumour effects of alpha-GalCer.

Different levels of TGFbeta, IL-10, IFNgamma and gelatinase A occur in experimental white and black metastases induced by bryostatin 1 or by phorbol ester-treated BL6T murine melanoma cells

Bryostatin 1 and phorbol esters reduce the intracellular melanin level in high metastatic overexpressing nPKCdelta BL6 (BL6T) cells, thereby inducing white experimental metastasis in syngeneic mice. We evaluate here the possible differences between white and black metastases induced by both treatments on the proliferative and metastatic potential as well as on the expression of some cytokines involved in the metastatic process such as TGFbeta, IL-10 and IFNgamma. The level of expression of gelatinase A is also considered. White and black metastases induced after the injection of bryostatin 1- or phorbol ester-treated cells into the tail vein of syngenic mice were isolated and analysed for the levels of LDH usually used as markers of cytotoxicity, for the levels of cytokines and gelatinase A or dissociated and cultured in vitro for a few passages. The cultured cells were analysed in vitro for the proliferative capacity and the melanin synthesis. The same cells were also re-injected into syngeneic mice and the number of experimental metastases were counted after 17 days or injected with matrigel in order to quantify the proliferative capacity in vivo. The results show only one significant difference between bryostatin I and phorbol ester, namely the cells obtained from white bryostatin 1-treated cells return to a black phenotype after a few passages in culture. This suggests that PKC mediates many of the biological effects of bryostatin 1 but that its effect is lost in vitro. On the other hand, white and black metastases (at least for metastases induced by BL6T cells treated with phorbol ester) do appear significantly different. In vivo white metastases show lower levels of LDH, lower levels of proliferative capacity into matrigel, higher levels of TGFbeta and IFNgamma and, when re-injected into syngeneic mice, give big black metastases. Therefore, in murine melanoma cells, the treatment with bryostatin I induces the appearance of a white population expressing different levels of TGFbeta, IFNgamma, IL-10 and gelatinase A. Such a white population is more difficult to diagnose and is capable of turning into a more aggressive phenotype under suitable environmental conditions.

Intracellular bacteria as targets and carriers for vaccination

In this review we discuss intracellular bacteria as targets and carriers for vaccines. For clarity and ease of comprehension, we focus on three microbes, Mycobacterium tuberculosis, Listeria monocytogenes and Salmonella, with an emphasis on tuberculosis, one of the leading causes of death from infectious disease. Novel vaccination strategies against these pathogens are currently being considered. One approach favors the use of live attenuated vaccines and vaccine carrier strains thereof, either for heterologous antigen presentation or DNA vaccine delivery. This strategy includes both the improvement of attenuated vaccine strains as well as the 'de novo' generation of attenuated variants of virulent pathogens. An alternative strategy relies on the application of subunit immunizations, either as nucleic acid vaccines or protein antigens of the pathogen. Finally, we present a short summary of the vaccination strategies against tuberculosis.

Advances in specific immunotherapy of malignant melanoma

Management of malignant melanoma continues to present a challenge to dermatologists, particularly in advanced cases. In light of the steady increase in the worldwide incidence and mortality rates for melanoma, better understanding of the immune mechanisms regulating melanoma progression and interaction with the host's immune system seems eminently important. New studies on the role of immune mechanisms in the pathogenesis and clinical course of melanoma have recently been published. We review the immune mechanisms involved in tumor progression and ways in which these mechanisms may be applied toward immunotherapeutic management of malignant melanoma.

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with (1) the immune mechanisms involved in host-tumor interaction and tumor rejection, (2) factors allowing the escape of melanoma cells from immune recognition, and (3) the current rationale for the different types of specific immunotherapy in melanoma. Better understanding of basic mechanisms in tumor immunology should raise awareness of future immunotherapeutic approaches in patients with melanoma, particularly in those who are at high risk of recurrence or who present with advanced disease.

The potential for monocyte-mediated immunotherapy during infection and malignancy--Part II: in vivo activation by exogenous cytokines and clinical applications

The monocyte system exhibits a range of immunological mechanisms that may be harnessed for therapeutic effect against infection and malignancy. The advent of novel therapies aimed at treating infection and malignancy is complemented by a resurgence of clinical interest in immunotherapeutic programmes to treat diseases by modification or direct augmentation of host immunity. Cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-gamma modulate the function of monocytes and have been used to experimentally probe the immunotherapeutic potential of monocytes against micro-organisms and malignancy. However, monocytes rarely act alone but communicate with other leukocytes involved in cell-mediated immunity. In particular monocytes cooperate with the T-helper (Th1 and Th2) sub-populations of peripheral lymphocytes. Moreover, sub-populations of monocytes, as identified by the co-expression of membrane-associated CD14 and CD16, have been shown to exist. At the preclinical level, this provides a unique opportunity to explore the effect of immunotherapeutic strategies on the function of monocyte sub-populations against infectious or malignant challenge and may allow immunotherapeutic strategies to be targeted towards specific monocyte sub-populations. Preclinical and clinical studies in human subjects suggest that GM-CSF and other cytokines such as IFN-gamma are the most promising biological response modifiers for augmenting monocyte-mediated immunity. In this review, the immunotherapeutic potential of the monocyte system will be discussed in the context of combating microbial and malignant disease.

[Managing cutaneous melanoma]

Cutaneous melanoma represents the main cause of death among skin cancers. Early diagnosis gives, for the time being, the only possibility for high rate of curative treatment. Diagnosis is based on pathological findings, and at primary tumor stage. Breslow thickness of the lesion is the best prognostic index. At local stage of the disease, treatment is precisely codified by international recommendations and consensus conferences. Follow-up after surgical treatment is also well codified. Treatment of lymph node invasion or metastatic disease is, on the other hand, less codified. Despite recent advances, especially in immunotherapy, treatment of advanced stages of melanoma remains difficult.

Superficial bladder cancer: the role of interferon-alpha

PURPOSE

We evaluate the clinical experience with recombinant interferon-alpha in superficial transitional cell carcinoma and discuss the most rational use of recombinant interferon-alpha in the context of current treatment options.

MATERIALS AND METHODS

The available data were reviewed and discussed at a consensus conference in August 1996. The conclusions and recommendations are those of the authors based on the consensus reached at that meeting.

RESULTS

While bacillus Calmette-Guerin (BCG) is recognized as the most efficacious intravesical agent in the prophylaxis and treatment of superficial transitional cell carcinoma, it is associated with significant toxicities and a 20 to 40% relapse rate. Interferons, particularly recombinant interferon-alpha, have demonstrated efficacy against primary and recurrent papillary transitional cell carcinoma and carcinoma in situ with minimal toxicity, although the response and relapse rates are inferior to BCG. Intravesical recombinant interferon-alpha therapy has also produced responses in patients who failed to respond or were refractory to BCG or chemotherapy.

CONCLUSIONS

The clinical experience suggests that recombinant interferon-alpha has an important role in the treatment of superficial transitional cell carcinoma, particularly as second line therapy following failure of BCG or chemotherapy, and it may have synergistic effects when combined with chemotherapy or BCG. We propose a prospective randomized study comparing the efficacy of recombinant interferon-alpha, BCG and BCG plus recombinant interferon-alpha as maintenance following complete response to primary BCG therapy. The proposed study would also investigate the efficacy of BCG plus recombinant interferon-alpha as second line therapy following BCG failure. This study will be important to determine the most effective strategy to integrate recombinant interferon-alpha into current treatment options for superficial bladder cancer.

The genetic reconstruction of BCG as a new immunotherapeutic tool

The bacillus of Calmette and Guérin (BCG), long appreciated for its role as a live vaccine for the prevention of tuberculosis, is undergoing a rebirth as a recombinant delivery vehicle for foreign antigens and bioactive proteins. Recombinant BCG causes long-lived specific humoral and cellular immunity and may ultimately prove to be a powerful and cost-effective new weapon against both infectious pathogens and certain cancers.