Abstract 6461: The spatial cellular landscape of Gleason pattern 3 and 4 prostate tumors

The cellular heterogeneity of prostate cancer cells has been well-established, yet the spatial diversity of stromal cells in the tumor microenvironment remains largely unexplored. In this study, we utilized cyclic immunofluorescence imaging of whole-tissue sections to map spatial relationships between cancer cells and various immune and non-immune stromal populations in primary Gleason pattern 3 and 4 tumors. Our analysis identified over 20 androgen receptor (AR)-positive stromal cell types, many of which have minimal data on their response to AR inhibitors. Notably, we identified distinct AR+ mast cell populations exhibiting unique spatial associations with M2 macrophages and regulatory T cells. Using spatial statistical tools and recurrent cellular neighborhood analysis, we identified disease-specific microenvironments predominantly driven by AR+ stromal cells and uncovered inflammatory gene networks active within AR+ stromal regions. Future work will expand this analysis to spatiotemporal profiling of intermediate-risk patients, aiming to improve tumor stratification for more precise clinical decision-making. Citation Format: Çiğdem Ak, Zeynep Sayar, Guillaume Thibault, M.J. Kuykendall, George Thomas, Vasilis Stavrinides, Young Hwan Chang, Ece S. Eksi. The spatial cellular landscape of Gleason pattern 3 and 4 prostate tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6461.