Antibiotic use attenuates response to immune checkpoint blockade in urothelial carcinoma via inhibiting CD74-MIF/COPA: revealing cross-talk between anti-bacterial immunity and anti-tumor immunity through a tumor marker prognostic study

Background: Immune checkpoint blockade (ICB) has emerged as a promising therapy for both resectable urothelial carcinoma (UC) patients preparing for radical surgery and unresectable UC patients, whereas the objective response rate of ICB remains unsatisfactory due to various factors. Antibiotic (ATB) use can influence intra-tumoral bacteria, which may further reduce ICB efficacy. The study aims to evaluate the effects of ATB use on prognosis and response in UC patients undergoing ICB, and explore potential molecular mechanisms of ATBs and intra-tumoral bacteria impacting UC immune microenvironment. Materials and Methods: Pooled analyses, synthesizing evidence from 12 studies and 3496 UC patients with ICB treatment, was conducted via a meta-analysis. In addition, single-cell RNA and single-cell microbiome data were analyzed based on eight UC samples and 63185 single cells. Bulk RNA sequencing and clinical data from a single-arm, multi-center, atezolizumab-treated, phase 2 trial, IMvigor210, were used for validation. The study is registered at PROSPERO (XXX) and at Research Registry (XXX). Results: ATB use exhibited worse overall survival (HR=1.46, 95%CI=[1.20, 1.77], P <0.001, heterogeneity I²=51%) and lower objective response (OR=0.43, 95%CI=[0.27, 0.68], P <0.001, heterogeneity I²=0%) in UC patients receiving ICB. Single-cell transcriptome and single-cell microbiome analyses identified the presence of intra-tumoral bacteria was obviously related to elevated anti-bacterial immune functions; and anti-bacterial immunity was positively correlated to anti-tumor immunity in UC immune microenvironment. Intra-tumoral bacteria could up-regulate CD74-MIF/COPA signaling of immune cells and activation of CD74-MIF/COPA mediated the promotion of T cell anti-tumor function induced by anti-bacterial immune cells. UC patients with higher CD74-MIF/COPA signaling carried better overall survival (HR=1.60, 95%CI=[1.19, 2.15], P =0.002) in IMvigor210 immunotherapy cohort. Conclusion: ATB use reduces overall survival and objective response to ICB in UC patients. Anti-bacterial immune cell functions induced by intra-cellular bacteria in UC microenvironment might up-regulate the function of anti-tumor T immune cells via activating CD74-MIF/COPA , whereas ATB could inhibit the above process through killing intra-cellular bacteria and result in poorer clinical benefit of ICB. The use of ATB should be considered carefully during neoadjuvant immunotherapy period for resectable UC patients preparing for radical surgery and during immunotherapy period for unresectable UC patients.