Specific binding of bacillus Calmette-Guérin to urothelial tumor cells in vitro

BCG in Bladder Cancer Immunotherapy

BCG is a live attenuated strain of Mycobacterium bovis that is primarily used as a vaccine against tuberculosis. In the past four decades, BCG has also been used for the treatment of non-muscle invasive bladder cancer (NMIBC). In patients with NMIBC, BCG reduces the risk of tumor recurrence and decreases the likelihood of progression to more invasive disease. Despite the long-term clinical experience with BCG, its mechanism of action is still being elucidated. Data from animal models and from human studies suggests that BCG activates both the innate and adaptive arms of the immune system eventually leading to tumor destruction. Herein, we review the current data regarding the mechanism of BCG and summarize the evidence for its clinical efficacy and recommended indications and clinical practice.

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.

Is ureteral stent an effective way to deliver drugs such as bacillus Calmette-Guérin to the upper urinary tract? An experimental study

Background:

We aim to evaluate the distribution in the upper urinary tract of intravesical-delivered fluids, after inducing vesicoureteral reflux (VUR) with a double J stent.

Methods:

In group 1 (n = 35) patients were maintained in a 20° Trendelenburg position and were evaluated after immediate insertion of ureteral stent, while in group 2 (n = 16) patients were evaluated after several days with ureteral stent placement. Patients in both groups were submitted to a cystogram with progressive volumes of iodine contrast and were evaluated according to VUR of contrast medium to the renal pelvis. Additionally, in group 2 visual confirmation was performed by endoscopic inspection of upper tract mucosal impregnation with methylene blue.

Results:

In group 1, after immediate insertion of ureteral stent reflux occurred in 51.4% (n = 18/35), and after several days with ureteral stent placement reflux was observed in 87.5% (n = 14/16) of patients. Reflux was progressively more frequent according to increasing bladder volume (p < 0.001). At 60 ml bladder volume no reflux was observed, while at 120 ml, 180 ml, 240 ml, 300 ml and 360 ml bladder volume reflux was observed in 14%, 25%, 41%, 55% and 63% of patients, respectively.

Conclusion:

Retrograde delivery of fluids such as bacillus Calmette-Guérin to the upper urinary tract through double J stents can be effective; however, it is mainly effective after several days with ureteral stent and relatively large volumes might be instilled into the bladder.

The Dose-Response Relationship of bacillus Calmette-Guérin and Urothelial Carcinoma Cell Biology

PURPOSE

Attenuated mycobacterium bacillus Calmette-Guérin is widely used as intravesical immunotherapy of nonmuscle invasive urothelial carcinoma. Currently there are limited data on the relationship between bacillus Calmette-Guérin dose intensity and tumor response. We evaluated the dose-response relationship of bacillus Calmette-Guérin to nonmuscle invasive bladder cancer in vitro using urothelial carcinoma cell lines and in vivo using an orthotopic mouse model.

MATERIALS AND METHODS

Two human urothelial carcinoma cell lines were used to study the effect of bacillus Calmette-Guérin dose on the tumor cell response. Internalization, activation of signaling pathways, gene transactivation, cell viability, lactate dehydrogenase and HMGB1 release were study end points. An orthotopic tumor model was used to compare the effect of different doses on the antitumor efficacy of bacillus Calmette-Guérin.

RESULTS

Bacillus Calmette-Guérin internalization by urothelial carcinoma cells increased as a function of time and dose with a plateau at higher doses and/or long exposure times. Intracellular signaling demonstrated a similar direct, dose dependent increase. Cytokine expression by urothelial carcinoma cells as a function of dose was variable. Some genes increased progressively but others showed a decrease at the highest dose. While nonviable cell number increased in proportion to dose, the number of cells undergoing necrotic cell death decreased at higher doses. A higher dose of bacillus Calmette-Guérin (1:200) showed a better antitumor effect than a standard dose (1:50) (p <0.01).

CONCLUSIONS

Bacillus Calmette-Guérin dose has a direct impact on urothelial carcinoma cell biology. Increased dose intensity, particularly in nonresponders, may represent a strategy to increase bacillus Calmette-Guérin treatment efficacy.

The mechanism of action of BCG therapy for bladder cancer--a current perspective

Bacillus Calmette-Guérin (BCG) has been used to treat non-muscle-invasive bladder cancer for more than 30 years. It is one of the most successful biotherapies for cancer in use. Despite long clinical experience with BCG, the mechanism of its therapeutic effect is still under investigation. Available evidence suggests that urothelial cells (including bladder cancer cells themselves) and cells of the immune system both have crucial roles in the therapeutic antitumour effect of BCG. The possible involvement of bladder cancer cells includes attachment and internalization of BCG, secretion of cytokines and chemokines, and presentation of BCG and/or cancer cell antigens to cells of the immune system. Immune system cell subsets that have potential roles in BCG therapy include CD4(+) and CD8(+) lymphocytes, natural killer cells, granulocytes, macrophages, and dendritic cells. Bladder cancer cells are killed through direct cytotoxicity by these cells, by secretion of soluble factors such as TRAIL (tumour necrosis factor-related apoptosis-inducing ligand), and, to some degree, by the direct action of BCG. Several gaps still exist in our knowledge that should be addressed in future efforts to understand this biotherapy of cancer.

Response of high-risk of recurrence/progression bladder tumours expressing sialyl-Tn and sialyl-6-T to BCG immunotherapy

Background:

High risk of recurrence/progression bladder tumours is treated with Bacillus Calmette-Guérin (BCG) immunotherapy after complete resection of the tumour. Approximately 75% of these tumours express the uncommon carbohydrate antigen sialyl-Tn (Tn), a surrogate biomarker of tumour aggressiveness. Such changes in the glycosylation of cell-surface proteins influence tumour microenvironment and immune responses that may modulate treatment outcome and the course of disease. The aim of this work is to determine the efficiency of BCG immunotherapy against tumours expressing sTn and sTn-related antigen sialyl-6-T (s6T).

Methods:

In a retrospective design, 94 tumours from patients treated with BCG were screened for sTn and s6T expression. In vitro studies were conducted to determine the interaction of BCG with high-grade bladder cancer cell line overexpressing sTn.

Results:

From the 94 cases evaluated, 36 had recurrence after BCG treatment (38.3%). Treatment outcome was influenced by age over 65 years (HR=2.668; (1.344–5.254); P=0.005), maintenance schedule (HR=0.480; (0.246–0.936); P=0.031) and multifocallity (HR=2.065; (1.033–4.126); P=0.040). sTn or s6T expression was associated with BCG response (P=0.024; P<0.0001) and with increased recurrence-free survival (P=0.001). Multivariate analyses showed that sTn and/or s6T were independent predictive markers of recurrence after BCG immunotherapy (HR=0.296; (0.148–0.594); P=0.001). In vitro studies demonstrated higher adhesion and internalisation of the bacillus to cells expressing sTn, promoting cell death.

Conclusion:

s6T is described for the first time in bladder tumours. Our data strongly suggest that BCG immunotherapy is efficient against sTn- and s6T-positive tumours. Furthermore, sTn and s6T expression are independent predictive markers of BCG treatment response and may be useful in the identification of patients who could benefit more from this immunotherapy.

The expression level of ligands for natural killer cell receptors predicts response to bacillus Calmette-Guerin therapy: a pilot study

PURPOSE

Up to 90% of patients with high grade superficial bladder tumors experience tumor recurrence and up to 50% have progression despite bacillus Calmette-Guerin treatment. Natural killer cells have a major role in the mechanism of the response to bacillus Calmette-Guerin but the exact mechanisms are still elusive. The recently discovered natural cytotoxicity receptors are linked to the host response to viral infection and to cancer. We tested the hypothesis that tumor expression of natural cytotoxicity receptor ligands can serve as a predictive factor for the response to intravesical bacillus Calmette-Guerin in patients with nonmuscle invasive, high grade bladder cancer.

MATERIALS AND METHODS

We developed a histochemical staining method for analysis of the ligands of the 3 known natural cytotoxicity receptors NKp30, NKp44 and NKp46 using genetically engineered fusion proteins and an automated image analysis system. We examined formalin fixed, paraffin embedded sections of specimens of transurethral bladder tumor resection from patients with primary, nonmuscle invasive, high grade bladder cancer who were subsequently treated with bacillus Calmette-Guerin. We compared natural cytotoxicity receptor ligand expression to the response to bacillus Calmette-Guerin immunotherapy.

RESULTS

Six of 17 patients (35%) had recurrence despite bacillus Calmette-Guerin treatment. Primary tumors from favorably responding patients expressed higher levels of ligands for all 3 fusion proteins (NKp30, NKp44 and NKp46 p = 0.0026, 0.027 and 0.044, respectively).

CONCLUSIONS

Bacillus Calmette-Guerin resistant, high grade, nonmuscle invasive bladder tumors express significantly lower levels of ligands of all 3 natural cytotoxicity receptors compared with bacillus Calmette-Guerin responsive tumors. This suggests that down-regulation of these ligands facilitates escape from the bacillus Calmette-Guerin effect. Furthermore, analysis of ligand expression, which can be performed on formalin fixed, paraffin embedded sections, may serve as a new predictive assay for the response to bacillus Calmette-Guerin.

ASSESSMENT OF VESICOURETERAL REFLUX IN PATIENTS WITH SELF-RETAINING URETERAL STENTS: IMPLICATIONS FOR UPPER URINARY TRACT INSTILLATION

PURPOSE

Conservative treatment of upper urinary tract tumors has been popularized during the last decade. Like in bladder cancer management, localized adjuvant therapy has been advocated to reduce the risk of disease recurrence or progression. In this study we tested the feasibility of creating vesicoureteral reflux (VUR) using a Double-J stent (Medical Engineering Corp., New York, New York) as a measure of efficacy for intravesical adjuvant treatment of the ureter and renal collecting system.

MATERIALS AND METHODS

The cohort included 100 consecutive patients in whom a Double-J stent was inserted for renal obstruction. All the patients underwent cystography in the supine position by retrograde filling of the bladder with a 50% dilute solution of 300 mgI/ml iopromide in serial increments of 50 ml up to a maximum of 350 ml. A total of 41 patients underwent cystography immediately following stent insertion (early group) and 59 patients with indwelling stents underwent cystography before further endourological intervention (late group). The presence of VUR and the level along the ureter and renal collecting system were assessed fluoroscopically.

RESULTS

Overall VUR was detected in 56 patients (56%), specifically 11 of the 41 (27%) in the early group and 45 of the 59 (76%) in the late group (p <0.001). There was no correlation between stent diameter or length and VUR, or between patient sex, age or particular side and the likelihood of reflux. Mean minimal intravesical volume required to obtain reflux was 171 +/- 11 ml, which was significantly higher in the early (255 +/- 21 ml) than in the late (146 +/- 11 ml) cystogram group. In 24 of the 56 patients (43%) with VUR, there was complete visualization of the entire ureter and renal collecting system. However, 15 patients (26%) had opacified renal pelves and calices without concomitant visualization of the ureters, whereas 7 patients (31%) had reflux to the ureter without opacification of the renal pelvis.

CONCLUSIONS

VUR is not a guaranteed consequence of Double-J stent placement. Therefore, when upper urinary tract instillation with the Double-J technique is considered, a cystogram should be performed first to confirm the occurrence of reflux, determine the intravesical volume required to induce reflux and ascertain that the pertinent section of the ureter or pelvicaliceal system from which the tumor was initially removed is opacified during study. An interval that remains to be defined should be allowed between stent insertion and VUR assessment.

Role of urothelial cells in BCG immunotherapy for superficial bladder cancer

Intravesical instillation of Bacillus Calmette-Guérin (BCG) is used for the treatment of superficial bladder cancer, both to reduce the recurrence rate of bladder tumour and to diminish the risk of progression. Since its first therapeutic application in 1976, major research efforts have been directed to decipher the exact mechanism of action of the BCG-associated antitumour effect. Bacillus Calmette-Guérin causes an extensive local inflammatory reaction in the bladder wall. Of this, the massive appearance of cytokines in the urine of BCG-treated patients stands out. Activated lymphocytes and macrophages are the most likely sources of these cytokines, but at present other cellular sources such as urothelial tumour cells cannot be ruled out. Bacillus Calmette-Guérin is internalised and processed both by professional antigen-presenting cells and urothelial tumour cells, resulting in an altered gene expression of these cells that accumulates in the presentation of BCG antigens and secretion of particular cytokines.

Intravesical instillation of bacille Calmette-Guérin for carcinoma in situ of the urothelium involving the upper urinary tract using vesicoureteral reflux created by a double-pigtail catheter

OBJECTIVES

To evaluate the therapeutic efficacy of bacille Calmette-Guérin (BCG) for carcinoma in situ (CIS) of the urothelium involving the upper urinary tract when the vaccine was administered by way of the bladder using vesicoureteral reflux created by a double-pigtail (DP) catheter.

METHODS

Thirteen upper urinary tracts of 9 patients with cytologically diagnosed CIS, with concomitant bladder CIS in 4, were treated by intravesical BCG instillation. A DP catheter was placed retrogradely, and the appearance of vesicoureteral reflux was confirmed by cystography. BCG (1 to 2 mg/mL) in a volume sufficient to fill the renal caliceal system was administered into the bladder weekly for 6 weeks. The mean follow-up was 36 months (range 8 to 97).

RESULTS

The voided urine cytology turned negative in all 9 patients at a mean of 86 days after the first administration of BCG. The voided urine cytology returned positive afterward in 3 patients, and positive cytology in the upper urinary tract was confirmed in 1 of 13 treated urinary tracts, which were successfully treated by another course of BCG therapy with the DP catheter. Minor adverse effects related to BCG and the DP catheter were seen in 5 patients.

CONCLUSIONS

BCG therapy for the CIS involving the upper urinary tract using a DP catheter might have the potential to be an effective procedure preserving renal units and could be adopted not only as an imperative, but also as an elective, treatment option.

Bacillus-Calmette-Guérin (BCG) and 3D tumors: an in vitro model for the study of adhesion and invasion

PURPOSE

To study adhesion, penetration and internalization of BCG and effector-cells to and into three-dimensional in vitro cell aggregates from benign and malignant urothelial origin mimicking small in vitro tumors.

MATERIALS AND METHODS

Multicellular spheroids (MCS) were generated by "liquid-overlay" technique. Adhesion and penetration of viable FITC-labelled BCG into MCS from urothelial cancer cell lines and normal urothelial cells was studied by electron microscopy (TEM) and fluorescence microscopy. Spheroid growth during BCG-co-incubation was determined by light microscopy. Peripheral blood mononuclear cells (PBMC) were stimulated with BCG to generate BCG-activated-killer (BAK) cells. The infiltration of these effectors and of lymphokine-activated killer (LAK) cells into MCS was examined at different intervals by means of immunohistochemistry. The resulting cytotoxicity was judged in a 3H-l-methionine release assay.

RESULTS

BCG adhered to MCS from tumor cells but not to benign cell MCS. Intracellular internalization of the bacteria was detectable in superficial tumor cell-layers (1-5) whereas BCG was not found in deeper layers. Proliferation of malignant MCS was reduced in the presence of BCG. Benign MCS showed contact inhibition growth arrest, which was not altered by BCG. BAK and LAK effector cells both infiltrated tumor cell MCS as opposed to unstimulated PBMC. In contrast to LAK cells, BAK cells did not infiltrate into benign cell MCS and were not cytotoxic towards them.

CONCLUSION

With regard to the clinical situation the selective adhesion and internalization of BCG to malignant cells might explain why BCG has been rarely found in follow-up biopsies in tumor free patients. More interestingly, the selective adhesion of BCG to and infiltration of BAK effector cells into malignant cell spheroids suggests a selective mode of action of BCG.