Intravesical Bacillus Calmette-Guérin (BCG) immunotherapy is the standard of care for high-risk non-muscle invasive bladder cancer (NMIBC), yet a substantial subset of patients fails to respond, highlighting the critical need for predictive biomarker...
Intravesical Bacillus Calmette-Guérin (BCG) immunotherapy is the standard of care for high-risk non-muscle invasive bladder cancer (NMIBC), yet a substantial subset of patients fails to respond, highlighting the critical need for predictive biomarkers. Despite the known association between systemic immunity and treatment outcomes, current clinical indices lack the resolution to accurately guide patient stratification. In this study, we utilized high-parameter mass cytometry (CyTOF) to comprehensively characterize peripheral blood immune profiles in NMIBC patients stratified by BCG treatment response. High-resolution analysis of 223,976 monocytes revealed that BCG-unresponsive patients exhibited significantly elevated CD192 (CCR2) and HLA-DR expression in Classical monocytes, indicative of a hyper-activated yet dysfunctional phenotype characterized by enhanced recruitment potential and chronic activation. A machine learning model integrating monocyte signatures achieved robust predictive performance (AUC = 0.841, 95% CI: 0.776–0.907), with HLA-DR emerging as the most important predictive feature. These results establish elevated CD192 and HLA-DR expression in circulating Classical monocytes as promising blood-based biomarkers for predicting BCG immunotherapy failure in NMIBC.