Abstract 5219: Loss of chromosome Y is unrelated to the composition of the tumor microenvironment and patient prognosis in muscle-invasive urothelial bladder cancers
Authors: Kluth Martina , Plage Henning , Hofbauer Sebastian , Furlano Kira , Weinberg Sarah , Franz Antonia , Fendler Annika , Roßner Florian , Schallenberg Simon , Elezkurtaj Sefer , Blessin Niclas C. , Lennartz Maximilian , Marx Andreas H. , Samtleben Henrik , Fisch Margit , Rink Michael , Slojewski Marcin , Kaczmarek Krystian , Ecke Thorsten , Koch Stefan , Adamini Nico , Simon Ronald , Sauter Guido , Weischenfeldt Joachim , Klatte Tobias , Minner Sarah , Horst David , Schlomm Thorsten , Zecha Dr. med Henrik Zecha 
Published: March 2024

Abstract
Background: Loss of chromosome Y (LOY) occurs commonly in cancers of male patients. It was recently proposed to be associated with cancer aggressiveness and altered T-cell function in bladder cancer and it was found to be linked to poor prognosis in a TCGA bladder cancer patient cohort of 300 patients based on a combined analysis of RNAs from Y-chromosome genes. In this study, we aimed to clarify the clinical relevance of LOY in a large cohort of urothelial bladder cancer patients by using fluorescence in-situ hybridization (FISH).
Design: X and Y chromosomes were analyzed by FISH on a tissue microarray (TMA) containing 1,819 urothelial carcinomas of the urinary bladder from male patients including 487 patients who had undergone cystectomy for muscle-invasive disease and for which follow-up data were available. Data of tumor microenvironment parameters were obtained in a previous study.
Results: LOY was found in 26.0% of 1,479 analyzable cancers. In the subset of non-invasive cancers, the frequency of LOY increased from pTaG2 (14.5%) to pTG3 (28.6%) but these differences were not significant (p=0.1015). In muscle-invasive cancers, the frequency of LOY increased slightly from pT2 (25.4%) to pT4 cancers (32.8%) but this association was again not significant (p=0.1868). Within pT2-4 cancers, LOY was associated with venous invasion (p=0.0010) but unrelated to pT, pN, and L-status, as well as to overall, recurrence-free, and cancer-specific survival. Muscle-invasive urothelial carcinomas with and without LOY did not show significant differences in the number of CD8 positive lymphocytes, the fraction of CD8 positive intraepithelial lymphocytes, the number of macrophages and dendritic cells, as well as the fraction of t helper and t regulatory cells.
Conclusion: FISH is the gold standard for determining LOY. That LOY was neither associated with histopathological parameters of cancer aggressiveness and patient prognosis nor with any parameters describing the tumor microenvironment strongly argues against a driving role of LOY for bladder cancer progression and cancer associated immune reaction. The slight increase of LOY from pTaG2 to pT4 cancers is consistent with a continuous (but clinically irrelevant) loss of the dispensable Y chromosomes during tumor evolution over time.
Citation Format: Martina Kluth, Henning Plage, Sebastian Hofbauer, Kira Furlano, Sarah Weinberg, Antonia Franz, Annika Fendler, Florian Roßner, Simon Schallenberg, Sefer Elezkurtaj, Niclas C. Blessin, Maximilian Lennartz, Andreas H. Marx, Henrik Samtleben, Margit Fisch, Michael Rink, Marcin Slojewski, Krystian Kaczmarek, Thorsten Ecke, Stefan Koch, Nico Adamini, Ronald Simon, Guido Sauter, Joachim Weischenfeldt, Tobias Klatte, Sarah Minner, David Horst, Thorsten Schlomm, Dr. med Henrik Zecha Zecha. Loss of chromosome Y is unrelated to the composition of the tumor microenvironment and patient prognosis in muscle-invasive urothelial bladder cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5219.