Background: Muscle-invasive bladder cancer (MIBC) represents approximately two thirds of invasive urothelial bladder cancers (UBC) and has high morbidity and mortality. Despite intensive efforts to improve patient treatment and outcome, two thirds of patients with UBC will have a recurrence or disease progression within 5 years. We conducted this study to gain further insights in the immunologic tumor microenvironment (TIME).

Material and Methods: Stromal tumor-infiltrating lymphocytes (sTILs) were scored continuously on HE slides in a cohort of 135 patients with MIBC treated by radical cystectomy (adjuvant chemotherapy n= 34) according to current recommendations (Salgado et al., 2015). In parallel, we assessed intrinsic subtypes by 21-gene Nanostring signature adapted from the MDACC-subtyping approach. Tertiary lymph structures were assessed by whole slide immunohistochemistry of CD3, CD8, CD68, and CD79a. Spatial immune profiling was carried out on regionally (tumor center, invasive margin) designed TMAs by CD3, CD8, CD56 (NK-cells), CD68, PD-1, and PD-L1 and revealed spatial organized immune phenotypes. Results were validated in 407 MIBC of the TCGA cohort by hierarchical clustering analysis, immune cell population analysis via CIBERSORT, and sTIL-scoring on digitalized HE-slides. Furthermore, tumor mutational burden, neoantigen load, and mutational patterns as well as mutational signatures were correlated with immune phenotypes in the TCGA cohort.

Results: We demonstrate that quantity and spatial distribution of sTILs within the tumor immune microenvironment (TIME) predict stages of tumor inflammation, subtypes, and patient survival and correlate with expression of immune checkpoints in an analysis of 542 MIBC. High sTILs indicate an inflamed subtype with 80% 5-year disease-specific survival. A lack of immune infiltrates identifies an uninflamed subtype with a survival rate of less than 25%. A separate immune-evading phenotype with upregulated immune checkpoints was associated with poor survival. Within the TIME are tertiary lymph node structures (TLS), which can mediate antitumor activity via active immune cells. High TLS amounts and close tumor distance correlated significantly with an inflamed phenotype and favorable survival. The uninflamed and evasion phenotypes showed lowest TLS numbers and farthest tumor distances and shortest survival. High inflammation also correlated with increased neoantigen load, high TMB, and specific mutational patterns (TCGA-MSig1, TCGA-MSig3/4). Patients treated with adjuvant chemotherapy showed a favorable prognosis dependent on high sTILs.

Conclusion: Determination of sTILs and tumor subtypes may stratify therapy success and patient survival. Considering sTILs can easily be quantified using simple morphologic parameters such as hematoxylin-eosin, sTILs can be implemented for predicting patient survival and outcome after adjuvant platinum-containing chemotherapy in a routine manner.

This abstract is also being presented as Poster A03.

Citation Format: Markus Eckstein, Carolin Pfannstiel, Katherine B. Chiappinelli, Danijel Sikic, Sven Wach, Ralph M. Wirtz, Adrian Wullweber, Helge Taubert, Johannes Breyer, Wolfgang Otto, Thomas Worst, Maximilian Burger, Bernd Wullich, Christian Bolenz, Nicole Fuhrich, Carol Geppert, Veronika Weyerer, Robert Stoehr, Simone Bertz, Bastian Keck, Franziska Erlmeier, Philipp Erben, Arndt Hartmann, Pamela Strissel, Reiner Strick. Tumor immune microenvironment drives prognostic relevance correlating with bladder cancer subtypes [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr PR04.