Characterization of the associated flora within colon cancer tumor tissues after application of Immune checkpoint blockade therapy revealed that Olsenella produces a metabolite called inosine, which enhances the effects of checkpoint blockade immunotherapy, particularly targeting cytotoxic T lymphocyte-associated antigen 4.[44] This result was similarly confirmed in bladder cancer, kidney cancer, and melanoma. Here, CTLA4 is linked to urinary bladder cancer.