Multiomics analysis of CXCL9+ macrophages in the immunotherapy response of bladder cancer

Background: Macrophages, key players in the immune system, are prevalent across diverse tissues. Within the tumor microenvironment, their functional roles drive the coevolution of the cancer ecosystem during tumor development, metastasis, and therapeutic responses. Methods: This study investigated the role of CXCL9 + macrophage in predicting ICI efficacy through integrated immunological analysis, including single-cell RNA (scRNA), spatial transcriptomics RNA (stRNA), and multi-omics analysis. Results: From 16 patients, 113,905 cells were classified into distinct clusters, with myeloid cells further sub-clustered into four primary macrophage populations: Macro-CCL4, Macro-CXCL9, Macro-FOLR2, and Macro-SPP1. Macro-CXCL9 was identified as pivotal in early macrophage differentiation and tumor immunity regulation. Spatial transcriptomics and transcription factor analyses revealed Macro-CXCL9's unique interactions and regulatory roles. The study employed CIBERSORTx for immune classification, highlighting Macro-CXCL9's association with improved immunotherapy responses. Pan-cancer analysis underscored the heterogeneity of immune cell interactions across cancer types. In bladder cancer, five distinct subtypes were identified, with Class E showing a higher abundance of Macro-CXCL9. A risk model, Mscore, was developed using Macro-CXCL9 marker genes to predict immune checkpoint blockade efficacy. Conclusions: High Mscores correlated with poorer survival and reduced treatment response, establishing Mscore as a robust prognostic indicator. Our findings provide insights into the role of Macro-CXCL9 in bladder cancer and suggest its potential as a biomarker for patient stratification and therapeutic targeting in precision immunotherapy. Further validation in clinical trials is warranted.