Strategies for Optimizing Bacillus Calmette-Guérin

Does Switching Bacillus Calmette-Guerin Strains During Maintenance Therapy Affect the Outcome in Non-Muscle Invasive Bladder Cancer?

OBJECTIVE

To compare the patients who have received 1 type of BCG strain during maintenance therapy with patients treated with multiple BCG strains.

MATERIAL AND METHODS

We reviewed 279 patients treated with BCG between January 2012 and May 2019, retrospectively. The primary endpoints of the study were recurrence-free survival (RFS) and progression-free survival (PFS) rates among patients receiving same BCG strain (Group-1) and multiple BCG strains (Group-2). Matching analysis was performed to balance the groups. The Kaplan-Meier method was used for estimating RFS and PFS. The difference between the 2 groups in terms of adverse effects was evaluated using the chi-square test.

RESULTS

A total of 225 (80.6 %) patients were treated with single BCG strain, and 54 (19.4 %) were treated with multiple BCG strains. Overall, recurrence and progression was observed in 86 (30.8%) and 38 (13.6%) patients, respectively. There was no significant difference between the 2 groups in terms of recurrence-free survival and progression-free survival on both without matching and with propensity score match analysis (log rank; P=.760 and P=.559, P=.533 and P=0509 for non-match and matched analysis respectively). Most of the patients in both groups experienced BCG therapy related side effects, but there was no statistically significant difference between groups (P=.235/.833).

CONCLUSIONS

Switching the BCG strain because of unavailability of the induction strain does not decrease the effectiveness of the treatment. When it is not possible to reach the starting BCG strain, treatment can be safely continued with any available strain.

Innate immune memory is associated with increased disease-free survival in bladder cancer patients treated with bacillus Calmette-Guérin

INTRODUCTION

While studies suggest that innate immune memory acquired by circulating monocytes may mediate the benefit of bacillus Calmette-Guérin (BCG) in the treatment of patients with high-risk non-muscle-invasive bladder cancer (NMIBC), prospective studies are lacking. Innate immune memory is defined by enhanced release of pro-inflammatory cytokines by innate immune cells following a secondary challenge with pattern recognition receptor (PRR) ligands.

METHODS

Peripheral blood monocytes isolated from 33 patients with intermediate- or high-risk NMIBC before and after two or five induction BCG instillations were stimulated with the PRR ligand lipopolysaccharide (LPS). Inflammatory cytokine levels in the culture medium were measured. Extent of innate immune memory acquisition was determined by dividing the levels of cytokines released after BCG instillation by the levels released prior to BCG therapy.

RESULTS

Monocytes secreted variable levels of TNFα, IL-1β, IL-6, IFNγ, IL-12, and IL-10. Compared with patients with recurrences, the post-BCG:pre-BCG ratio of IL-12 in monocyte cultures from patients without recurrences after five BCG instillations was significantly increased. Patients with no innate immune memory (based on IL-12 ratios) had significantly shorter time to recurrence than patients with innate immune memory (p<0.001). Eighty-four percent (16/19) of patients with innate immune memory vs. only 22% (2/9) of patients without memory had disease-free survival of over 500 days.

CONCLUSIONS

Results demonstrate a potential link between BCG-induced innate immune memory peripherally and local anti-tumor responses. Further validation will increase our understanding of the mode of action of BCG and, therefore, will be used to enhance its effectiveness.

Intravesical BCG: where do we stand? Past, present and future

High and intermediate risk non-muscle invasive bladder cancer poses a real challenge for treatment. Approximately 70% of bladder cancer presents as non-muscle invasive and 20–25% will progress to muscle invasive disease. Recurrences occur in up to 70% but treatment options are limited. Intravesical bacillus Calmette–Guérin is still considered the bladder sparing treatment of choice despite its well documented pitfalls. This review considers how bacillus Calmette–Guérin has become the recommended treatment, its benefits and risks and the alternative options for treatment.

Level of evidence: Not applicable for this multicentre audit.

Role of immunotherapy in bacillus Calmette-Guérin-unresponsive non-muscle invasive bladder cancer

Intravesical instillation of live attenuated bacillus Calmette-Guérin (BCG) is the gold standard for patients with intermediate- and high-risk non-muscle-invasive bladder cancer (NMIBC). BCG-failures include a heterogenous population of patients who share a designation of disease recurrence or progression following BCG and include patients with complete unresponsiveness to BCG, patients who respond initially but develop relapse and, in some cases, patients who are intolerant to BCG due to side effects. Given the efficacy and relatively rapid approval of several monoclonal antibodies against PD-L1 or PD-1 for advanced and metastatic bladder cancer, the role of these checkpoint inhibitors in BCG-relapsing disease at various disease stages is under consideration. Data supporting a role for immune checkpoint inhibitors is largely theoretical with limited supportive data from animal models and from clinical evidence of increased PD-L1 expression in BCG-unresponsive tumors. Current trials in BCG-unresponsive disease are underway and expected to provide insight regarding these concepts.

Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of bladder carcinoma

The standard of care for most patients with non-muscle-invasive bladder cancer (NMIBC) is immunotherapy with intravesical Bacillus Calmette-Guérin (BCG), which activates the immune system to recognize and destroy malignant cells and has demonstrated durable clinical benefit. Urologic best-practice guidelines and consensus reports have been developed and strengthened based on data on the timing, dose, and duration of therapy from randomized clinical trials, as well as by critical evaluation of criteria for progression. However, these reports have not penetrated the community, and many patients do not receive appropriate therapy. Additionally, several immune checkpoint inhibitors have recently been approved for treatment of metastatic disease. The approval of immune checkpoint blockade for patients with platinum-resistant or -ineligible metastatic bladder cancer has led to considerations of expanded use for both advanced and, potentially, localized disease. To address these issues and others surrounding the appropriate use of immunotherapy for the treatment of bladder cancer, the Society for Immunotherapy of Cancer (SITC) convened a Task Force of experts, including physicians, patient advocates, and nurses, to address issues related to patient selection, toxicity management, clinical endpoints, as well as the combination and sequencing of therapies. Following the standard approach established by the Society for other cancers, a systematic literature review and analysis of data, combined with consensus voting was used to generate guidelines. Here, we provide a consensus statement for the use of immunotherapy in patients with bladder cancer, with plans to update these recommendations as the field progresses.

Immune therapies in non-muscle invasive bladder cancer

OPINION STATEMENT

Non-muscle invasive bladder cancer (NMIBC) continues to be a challenging disease to manage. Treatment involves transurethral resection and, often, intravesical therapy. Appropriate patient selection, accurate staging, and morphological characterization are vital in risk-stratifying patients to those who would most benefit from receiving intravesical therapy. Bacillus of Calmette and Guérin (BCG) continues to be the first-line agent of choice for patients with intermediate- and high-risk NMIBC. Treatment should begin with the standard induction course of 6 weekly treatments. The inclusion of subsequent maintenance courses of BCG is imperative to optimal therapeutic response. While patients with intermediate-risk disease should receive 1 year of maintenance therapy, high-risk patients benefit from up to 3 years of maintenance therapy. BCG use should not be used in low-risk patients with de novo Ta, low-grade, solitary, <3-cm tumors. Conversely, patients with muscle-invasive disease should forgo intravesical immunotherapy and proceed directly to radical cystectomy. Cystectomy also should be considered in patients with multiple T1 tumors, T1 tumors located in difficult to resect locations, residual T1 on re-resection, and T1 with concomitant CIS. Although promising new immunotherapeutic agents, such as Urocidin, protein-based vaccines, and immune check point inhibitors are undergoing preclinical and clinical investigation, immunotherapy in bladder cancer remains largely reliant on intravesical BCG with surgical consolidation as the standard salvage treatment for patients with BCG failure.