Abstract LB466: Visium-HD spatial RNAseq analysis of aggressive prostatic adenocarcinoma identifies distinct RNA signatures in metastatic and non-metastatic disease

Abstract Background: There are limited studies regarding the tumor microenvironment of aggressive prostatic adenocarcinoma (PCa), at the single-cell level. In addition, there is a paucity of RNAseq data regarding gene expression of immune infiltrates and cancer-associated fibroblasts adjacent to PCa. The Visium-HD Spatial RNAseq platform sequences formalin-fixed paraffin embedded (FFPE) tissue using spatial barcodes at up to 2-micron pixel resolution, which achieves single-cell resolution. Design: We performed Visium-HD Spatial RNAseq analysis on FFPE blocks from radical prostatectomy specimens of 12 patients of which six had lymph node metastases (LNM) and six did not. All tissues analyzed by spatial RNAseq included foci of prostatic stroma adjacent to PCa and separate foci of benign glands and adjacent stroma. Results: Visium-HD RNAseq could readily identify distinct tumor microenvironments such as benign glands, stroma, Gleason IV tumor, Gleason V tumor, and Tumor Necrosis. We observed that patients with LNM had more significant enrichment for gene signatures associated with inflammation and immune responses and high numbers of naïve regulatory T cells (Naïve Treg) near the invasive front of the aggressive tumor foci. The cancer-associated stroma in metastatic patients was enriched in expression of antigen presenting genes, but also in immunosuppressive gene signatures. We also observed tumor cells with neuroendocrine prostate cancer gene expression patterns in these patients who had not yet received any androgen-deprivation therapy. Tumors of patients with LNM were also more enriched in proliferative gene signatures such as E2F Targets, G2M Checkpoint genes, and Mitotic spindle genes. Finally, tumors of patients with LNM were enriched for gene expression indicative of endogenous cholesterol biosynthesis, whereas non-metastatic tumors were not. Conclusions: High-definition spatial RNAseq analysis with the Visium-HD platform enables automated identification of biologically and pathologically distinct regions of the PCa tumor microenvironment. Tumors of patients with metastatic disease had greater expression of immune gene sets, proliferative gene sets, and genes associated with cholesterol metabolism. Citation Format: Rakesh Shiradkar, Tilak Pathak, Cynthia Winham, Ismaheel O. Lawal, Olayinka A. Abiodun-Ojo, Martin G. Sanda, David M. Schuster, Adeboye O. Osunkoya, Carlos S. Moreno. Visium-HD spatial RNAseq analysis of aggressive prostatic adenocarcinoma identifies distinct RNA signatures in metastatic and non-metastatic disease [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB466.