Introduction: The prognosis of muscle-invasive urothelial bladder cancer (MIBC) is poor and response rates to systemic therapy are insufficient. Infiltration of tumors by immune cells has been described to be associated with response rates to immune- and chemotherapy and patient’s outcome. However, tumor-associated macrophages (TAMs) are abundant in many tumors and can promote cancer progression. In this study we evaluate different subsets of immune cells in the tumor microenvironment (TME) as predictors of prognosis in MIBC and survival rates with adjuvant chemotherapy. Methods: We used multiplex immunohistochemistry (IHC) to quantify and characterize immune, tumor and stroma cells: double negative T-cells (CD3+CD4-CD8-); T-helper cells (CD4+); cytotoxic T-cells (CD8+); PD-1 positive T-cells; macrophages (CD163+); regulatory T-cells (Tregs; FoxP3+)); fibroblasts (Vimentin+); immune cells (CD45+); tumor cells (panCK+); PD-L1 positive tumor cells; proliferating immune cells (CD45+Ki67+); proliferating tumor cells (panCK+Ki67+). Analysis was performed in 101 MIBC patients receiving radical cystectomy. Uni- and multivariate Cox regression were used to identify cell types that predict prognosis. Patients were divided into three clusters for their macrophage and Treg infiltration. Results: High Treg infiltration was associated with better overall survival (OS) (HR 0.1, 95%CI 0.01-0.7; p=0.03) and high macrophage infiltration was associated with decreased OS (HR 10.9, 95%CI 2.8-40.5; p=0.0004) in the multivariate Cox-regression model adjusting for tumor stage, lymph node status and application of adjuvant chemotherapy. The cluster with high Treg concentration was also enriched for other immune cells and cells showed high PD1 and PD-L1 expression. Patients in the cluster with high macrophage concentration had the worst OS also when adjuvant chemotherapy was given. We validated the findings using standardized IHC for CD163 as a macrophage marker using a digital analysis software in 141 patients. Conclusions: In MIBC high macrophage concentration is an independent predictor of poor prognosis. High levels of Tregs are associated with other immune cells in the TME which might lead to better survival rates. Using routine IHC for TAMs (CD163) should be prospectively validated to confirm findings and to evaluate the predictive value for response to systemic therapies. SOURCE OF Funding: Deutsche Krebshilfe (German Cancer Aid). Wilhelm-Sander Foundation. Hessen State Ministry for Higher Education, Research and the Arts.
