Intraepithelial CD8+ cytotoxic T-cells are the main component of the immune tumor microenvironment that drive prognosis in muscle-invasive bladder cancer

Abstract

Abstract Introduction/Objective Quantity and the spatial relationship of individual immune cell (sub)types can provide prognostic information in muscle-invasive bladder cancer. Methods/Case Report To study the prognostic role of different immune cell subpopulations in muscle-invasive bladder cancer, we stained 521 muscle-invasive urothelial bladder carcinomas with 21 antibodies using BLEACH&STAIN multiplex fluorescence immunohistochemistry (mfIHC) in a tissue microarray format. A framework of neuronal networks was trained and used for image analysis. Results (if a Case Study enter NA) The identification of more than 300 different immune cell subpopulations and the characterization of their spatial relationship resulted in numerous spatial interaction patterns. 40 immune parameters showed prognostic significance in univariate analyses of which 15 were independent from pT, pN, and histologic grade. The strongest association to clinical outcome was identified for intraepithelial CD8+cytotoxic T-cells (tAUC: 0.70) compared to all other 15 independent prognosis parameters (AUC: ≤0.68, p=0.039). Deeper spatial analysis revealed an increased expression levels of TIM3, CTLA-4 and PD-1 on CD8+ T cells that were located in the intraepithelial compartment. Furthermore, the cell-to-cell interaction profile of intraepithelial CD8+ T-cells was dominated by intraepithelial dendritic cells as well as intraepithelial M1-macrophages. Conclusion The intraepithelial CD8+T-cells that showed the highest expression level of TIM-3, PD-1 and CTLA-4 and were strongly interacting with M1-macrophages as well as dendritic cells and represented the strongest prognostic parameter in muscle-invasive bladder cancer. This can be explained by the fact that tumor cell destruction by CD8+ cytotoxic T-lymphocytes through direct cell-to-cell-contacts represents the “terminal-end-route” of anti-tumor immunity. The strongest prognostic immune-factor – intraepithelial CD8+T-cells – can be measured straightaway in routine pathology as the CD8-labelling index using conventional bright field immunohistochemistry.