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In non-muscle invasive bladder cancer, Bacillus Calmette–Guérin (BCG) responders benefit from strong Th1-type inflammatory and T cell responses mediating tumor rejection. However, the corresponding lack of anti-inflammatory Th2-type immunity impairs tissue repair in the bladder wall and facilitates the development of cystitis, causing urinary pain, urgency, incontinence, and frequency. Mechanistically, the leakage of the glycosaminoglycan (GAG) layer enables an influx of potassium ions, bacteria, and urine solutes towards the underlying bladder tissue, promoting chronic inflammation. Treatments directed towards re-establishing this mucopolysaccharide-based protective barrier are urgently needed. We discuss the pathomechanisms, as well as the therapeutic rationale of how chondroitin and hyaluronic acid instillations can reduce or prevent BCG-induced irritative bladder symptoms. Moreover, we present a case series of five patients with refractory BCG-induced cystitis successfully treated with combined chondroitin and hyaluronic acid instillations. [ABSTRACT FROM AUTHOR]

BCG is the most efficient adjuvant therapy for high-risk, non-muscle-invasive bladder cancer (NMIBC). Both innate and adaptive immune responses have been implicated in BCG-mediated effects. BCG vaccination can boost innate immune responses via trained immunity (TI), resulting in an increased resistance to respiratory viral infections. Here we evaluated for the first time whether intravesical application of BCG triggers increased immunity against SARS-CoV-2 in patients with high-risk NMIBC. Serum and peripheral blood mononuclear cells (PBMCs) from heparinized whole blood samples of 11 unvaccinated SARSCoV-2-naïve high-risk NMIBC patients were collected at baseline and during BCG treatment in a pre-COVID-19 era. To examine B-cell or T cell-dependent adaptive immunity against SARS-CoV-2, sera were tested for the presence of SARS-CoV-2 neutralizing antibodies. Using a SARS-CoV-2 peptide pool, virusspecific T cells were quantified via IFNg ELISpot assays. To analyze innate immune responses, mRNA and protein expression levels of pro- and anti-inflammatory cytokines were measured after a 24-hour stimulation of PBMCs with either BCG or SARS-CoV-2 wildtype. ATAC-sequencing was performed to identify a potential epigenetic reprogramming in immune cells. We neither identified SARS-CoV-2 neutralizing antibodies nor SARS-CoV-2-reactive T cells, indicating that intravesical BCG did not induce adaptive immunity against SARS-CoV-2. However, a significant increase in mRNA as well as protein expression of IL-1β, IL-6 and TNFa, which are key cytokines of trained immunity, could be observed after at least four intravesical BCG instillations. Genomic regions in the proximity of TI genes (TLR2, IGF1R, AKT1, MTOR, MAPK14, HSP90AA1) were more accessible during BCG compared to baseline. Although intravesical BCG did not induce adaptive immune responses, repetitive intravesical instillations of BCG induced circulating innate immune cells that produce TI cytokines also in response to SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Simple Summary: Bacillus of Calmette-Guérin (BCG) is the gold standard as per adjuvant intravesical treatment for intermediate and high-risk non-muscle invasive bladder cancer (NMIBC). Nevertheless, drug-related toxicity, compliance, and a shortage of BCG availability make the completion of the planned treatment schedule challenging in many patients, thus possibly impacting survival outcomes. No one specific BCG strain out of the several available ones worldwide has so far demonstrated its superiority profile in prolonging time to recurrence and progression. In our systematic review and network meta-analysis, we compared to most widely adopted BCG strains and demonstrated that BCG strain Tice, RIVM, and Tokyo 172 could display potential enhanced benefits, thus possibly supporting the use of such strains for future BCG trials in NMIBCs. Background: In an era of Bacillus of Calmette-Guérin (BCG) shortages, the comparative efficacy from different adjuvant intravesical BCG strains in non-muscle invasive bladder cancer (NMIBC) has not been clearly elucidated. We aim to compare, through a systematic review and meta-analysis, the cumulative BC recurrence rates and the best efficacy profile of worldwide available BCG strains over the last forty years. Methods: PubMed, Scopus, Web of Science, Embase, and Cochrane databases were searched from 1982 up to 2022. A meta-analysis of pooled BC recurrence rates was stratified for studies with ≤3-y vs. >3-y recurrence-free survival (RFS) endpoints and the strain of BCG. Sensitivity analysis, sub-group analysis, and meta-regression were implemented to investigate the contribution of moderators to heterogeneity. A random-effect network meta-analysis was performed to compare BCG strains on a multi-treatment level. Results: In total, n = 62 series with n = 15,412 patients in n = 100 study arms and n = 10 different BCG strains were reviewed. BCG Tokyo 172 exhibited the lowest pooled BC recurrence rate among studies with ≤3-y RFS (0.22 (95%CI 0.16–0.28). No clinically relevant difference was noted among strains at >3-y RFS outcomes. Sub-group and meta-regression analyses highlighted the influence of NMIBC risk-group classification and previous intravesical treated categories. Out of the n = 11 studies with n = 7 BCG strains included in the network, BCG RIVM, Tice, and Tokyo 172 presented with the best-predicted probability for efficacy, yet no single strain was significantly superior to another in preventing BC recurrence risk. Conclusion: We did not identify a BCG stain providing a clinically significant lower BC recurrence rate. While these findings might discourage investment in future head-to-head randomized comparison, we were, however, able to highlight some potential enhanced benefits from the genetically different BCG RIVM, Tice, and Tokyo 172. This evidence would support the use of such strains for future BCG trials in NMIBCs. [ABSTRACT FROM AUTHOR]