Capturing age-related changes in the tumor microenvironment of luminal breast cancer using the multiplex immunohistochemistry technique, MILAN.

• DOI: 10.1200/jco.2023.41.16_suppl.e15089
• Publication Date: 2023-06-04T15:35:13Z
• Authors: Yentl Lambrechts; Asier Antoranz Ma...; Maxim De Schepper; Tatjana Geukens; Hanne Vos; Lieze Berben; Julie Messiaen; Lukas Marcelis; Yannick Van Herck; Patrick Neven; Ann Smeets; Kevin Punie; Christine Desmedt; Francesca Maria B...; Frederik De Smet; Sigrid Hatse; Hans Wildiers; Giuseppe Floris
• Keywords: Tissue microarray; Multiplex

e15089 Background: The ‘immune landscape’ of luminal breast tumors is poorly described to date. We applied the ‘multiple iterative labeling by antibody ‘neodeposition’ (MILAN) technique for in-depth characterization tumor microenvironment luminal-like cancer (BC) in relation age. Methods: Newly diagnosed patients with early BC (grade 2/3, ER+, HER2-, size ≥1,5 cm) were prospectively included UH Leuven between March 2014 and November 2015 divided into 3 distinct age categories (young: 35-45 yrs.; middle: 55-65 old: ≥70 yrs.). 55 n = 12; 16; 27) cohort. From each patient up 2 cores from center (TC) invasive front (IF) sampled formalin-fixed paraffin-embedded resection specimens embedded tissue microarrays. MILAN workflow 20 rounds three-color indirect immunofluorescence (FITC, TRITC, Cy5 channel combined 58 antibodies), image acquisition, removal/stripping antibodies before any other stain. data analysis pipeline was study expression phenotypic functional proteins at single-cell level including spatial resolution. These compared different groups using Wilcoxon's test (FDR correction). Results: identified 1,5 million cells, which 59% epithelial cells (cancer normal), 29% immune remaining 12% endothelial or stromal cells. Within cell fraction, T-helper (Th) B-cells, T-cytotoxic (Tcy) NK-cells significantly decreased aging while monocytes increased TC IF (Table 1). evaluation markers inflammatory revealed a PD-L1 Tcy (p < 0.001 IF), Th 0.003 T-regulatory (Treg) 0.038 TC), B-cells 0.023 TC). Perforin 0.05 IF) IF). OX-40 Treg 0.002 0.012 Conclusions: Our results suggest important compositional changes during BC. Further on types warranted. [Table: see text]