Abstract PR001: Spatial proximity between CD8+ T cells and tumor cells correlates with invasive recurrence in DCIS


 Purpose: The immune microenvironment in ductal carcinoma in situ (DCIS) and its significance are not well established. In this study, we characterized the immune microenvironment of DCIS to determine if immune cell densities, or their spatial relationships with tumor cells, are predictive of recurrence with invasive breast cancer. Methods: One hundred thirty-two cases of DCIS were included in this study. Seventy (53%) cases were high grade, 72 (54%) were HER2+, and 91 (69%) were HR+. Twenty cases recurred with invasive breast cancer. Immune infiltrates were characterized by multiplex immunofluorescence staining of FFPE sections using two 6-plex panels. Panel IP1.2 included markers for CD3, CD20, Foxp3, pan-cytokeratins, Ki67, and HLADR. Panel IP2.2 included markers for CD3, CD8, CD68, pan-cytokeratins, PD-1, and PD-L1. Staining was performed on a Leica Bond autostainer and images were acquired on a Vectra Polaris imaging system. Image analysis was performed utilizing inForm and QuPath software packages, as well as R scripts. Counts for each cell population were determined and spatial point pattern analyses were performed to quantitate the spatial relationships between tumor cells and various immune cell types. Results: High infiltrates of T cells, CD8+ T cells (Tc), Foxp3+ T cells, and B cells were associated with high grade, hormone receptor (HR) negativity, HER2 positivity, and the presence of comedonecrosis. PD-1+ T cells and PD-1+ Tc were associated with high grade, HR negativity, and HER2 positivity. PD-L1+ immune cells, but not PD-L1+ tumor cells, were also associated with high grade, HR negativity, and HER2 positivity. None of the cell populations were associated with invasive recurrence. However, the spatial proximity of tumor cells with T cells, in particular Tc, was significantly associated with a subsequent invasive event. Patients whose DCIS had a high tumor-to-Tc proximity score (indicating close proximity of tumor and Tc) were less likely to have an invasive recurrence. Conclusion: These findings suggest that the tumor immune microenvironment is an important factor in identifying DCIS cases at risk for invasive recurrence and that manipulating the immune microenvironment may be an efficacious strategy to alter or prevent disease progression.
 Citation Format: Michael J. Campbell, Nicole Schindler, Alexa Glencer, Jennifer Bolen, Hidetoshi Mori, Tristan Loveday, Harriet Rothschild, Gillian Hirst, Scott Vandenberg, Alexander Borowsky, Laura Esserman. Spatial proximity between CD8+ T cells and tumor cells correlates with invasive recurrence in DCIS [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr PR001.