Host-microbiota interactions in genitourinary cancer immunotherapy.

Immunotherapy for genitourinary cancer, including bladder cancer, renal cell carcinoma, and prostate cancer, has made significant progress in recent years; however, it still faces challenges such as low patient response rates, drug resistance and immune-related adverse events. As the "second genome" of the human body, the gut microbiota plays a key factor in modulating the host immune response. Studies have shown that host-microbiome interactions profoundly affect the efficacy and safety of immune checkpoint inhibitors by shaping the tumor immune microenvironment (TIME). This review systematically analyzes the mechanisms by which urinary system-specific microbiota (such as urothelial bacteria and gut microbiota) regulate TIME through metabolic regulation, immune cell function remodeling, and inflammatory signaling networks. We further explore the clinical translational strategy targeting the microbiome to enhance immunotherapy responses, providing new perspectives for precision immunotherapy of urinary tumors.