FimH confers mannose-targeting ability to Bacillus Calmette-Guerin for improved immunotherapy in bladder cancer

Abstract

BackgroundBladder cancer is a common disease worldwide with most patients presenting with the non-muscle-invasive form (NMIBC) at initial diagnosis. Postoperational intravesical instillation of BCG is carried out for patients with high-risk disease to reduce tumor recurrence and progression to muscle invasive disease. However, BCG can also have side effects or be ineffective in some patients because it cannot enter the cancer cells. Thus, to improve the efficacy of BCG immunotherapy is the long-term pursuit of the bladder cancer field.MethodsTo increase the adhesion of BCG to the urothelium we overexpressed FimH, a mannose binding protein naturally used by uropathogenic Escherichia coli to adhere to human urothelium, onto the surface of BCG. The adhesion/internalization ability of rBCG-S.FimH was examined in mouse bladder by fluorescence microscopy. Preclinical evaluation of antitumor efficacy was carried out in orthotopic mouse models of bladder cancer and in human peripheral blood mononuclear cells. Mechanistic studies were carried out using toll-like receptor 4 (TLR4) knockout mice. Immune cells and cytokines in the serum, tumor and lymph nodes were analyzed by flow cytometry, PCR, ELISA and ELISPOT.ResultsrBCG-S.FimH exhibited markedly improved adhesion and more rapid internalization into urothelial cells than wild-type BCG, resulting in more potent antitumor activity in orthotopic murine models of bladder cancer. To our surprise, rBCG-S.FimH elicited a much more prominent Th1-biased immune response known to be positively correlated with BCG efficacy. Mechanistic studies using TLR4 knockout mouse showed that rBCG-S.FimH could induce enhanced dendritic cell activation and tumor antigen-specific immune response in a TLR4-dependent manner. Furthermore, human peripheral blood mononuclear cells stimulated by rBCG-S.FimH also showed better tumoricidal effects than those using wild-type BCG.ConclusionrBCG-S.FimH is a novel BCG strain with significantly improved efficacy against bladder cancer. Since intravesical BCG immunotherapy is the first-line treatment for NMIBC, which accounts for more than 70% of all bladder cancer cases, our results provide a compelling rationale for clinical development.

BCG in Bladder Cancer Immunotherapy

“…A recent manuscript showed indirect evidence for this mechanism, demonstrating that BCG expressing the mannose-binding protein FimH had improved ability to adhere to urothelial cells and be internalized by them and also induced a more potent anti-tumor response as compared to wild type BCG. However, whether the improved efficacy of the FimH strain was through increased uptake by urothelial cells or via another mechanism was not shown [30].…”

Clinical value of M1 macrophage-related genes identification in bladder urothelial carcinoma and in vitro validation

“…BLCA is one of the most common and most aggressive malignancies, the worried is that little progress has been made in the treatment of BLCA in the last few decades ( Kimura et al, 2020 ; Lv et al, 2020 ). It is worth noticing that immunotherapy has shown great potential to treat MIBC and metastatic bladder cancer in the clinic ( Nair et al, 2020 ; Pfail et al, 2021 ; Zhang et al, 2022 ). Previous studies have found that macrophages exert different effects on immunotherapeutic responses in advanced cancers ( Petty and Yang, 2017 ; DeNardo and Ruffell, 2019 ; Zeng et al, 2020 ; Leblond et al, 2021 ).…”

High mannose level in bladder cancer enhances type 1 fimbria–mediated attachment of uropathogenic E. coli

“…These include lectin-drug conjugates and bacterial-based immunotherapies. The ConAepirubicin conjugate (Huo et al, 2022), and the adjuvant immunotherapies PA-MSHA (Wang et al, 2021) and rBCG-S.FimH (Zhang et al, 2022), were all shown to be more effective t h a n B C G , a g a i n s t b l a d d e r c a n c e r i n t h e mo u s e orthotropic model.…”

“…FimH is the distal component of type 1 fimbria that is expressed by many uropathogenic E. coli (UPEC) strains ( Emody et al., 2003 ; Gur et al., 2013 ), and plays a critical role in the interactions of UPEC with D-mannose -enriched bladder uroplakin Ia ( Zhou et al., 2001 ). Overexpression of FimH on the outer surface of a recombinant BCG (rBCG-S.FimH) was shown to markedly improve adhesion, expedite internalization into urothelial cells, and improve its immunotherapeutic effect for treating bladder cancer in mice, compared to the wild-type parental BCG ( Zhang et al., 2022 ).…”