Fluorinated Chitosan-Mediated Transepithelial Delivery of Intravesical Dual-Drug Immunotherapeutic for Bladder Cancer Therapy

Intravesical instillation-based immunotherapy for bladder-preservation of bladder cancer (BCa) treatment has not been explored. In the current study, two irrigated nano-formulations of immunological adjuvant-fluorinated chitosan (FCS) and therapeutic antibody-FCS are developed for synergistic immunotherapy against BCa. In this system, FCS is employed as a transepithelial carrier to assemble with bovine serum albumin (BSA)-flubendazole (FBZ) complex and anti-PD-1 (αPD-1) respectively, to facilitate efficient transepithelial delivery of intravesical FBZ-BSA and αPD-1 though transiently regulating the distribution of tight junction proteins on bladder epithelium. In addition, the FBZ–BSA complex exhibits tumor microenvironment-responsive charge reversal and BSA carrier-broken effects to drive tumor-targeted dissociation and drug release of FBZ–BSA/FCS. Moreover, FBZ not only promotes apoptosis and inhibits glycolysis in cancer cells but also displays adjuvant properties to activate potent immune responses through IL-12/IFN-γ pathway. Interestingly, combined perfusion of FBZ–BSA/FCS and αPD-1/FCS nano-formulations can significantly activate the tumor immune microenvironment, especially CD8⁺ T cell infiltration and αPD-1 sensitivity, and finally remarkably inhibit tumor growth in the mouse orthotopic BCa model. Thus, this study presents a novel intravesical delivery platform for ICB antibodies and a smart adjuvant system to achieve potent synergy immunotherapy, which is promising for bladder-preserving treatment against BCa.