Spatially distinct cellular and molecular landscapes define prognosis in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a prevalent breast cancer subtype with the lowest 5-year survival. Several factors influence outcomes, but their inherent molecular and cellular heterogeneity are increasingly acknowledged as crucial determinants. Here, we report on the spatio-molecular heterogeneity underlying TNBC tumors in a retrospective, treatment-naive cohort with differential prognoses (17 good prognoses [GPx] >15-year survival and 15 poor prognoses [PPx] <3-year survival]) profiled using GeoMx Digital Spatial Profiler. Analyses reveal that epithelial and microenvironment (TME) states are transcriptionally distinct between groups. Invasive GPx epithelia show an increase in immune transcripts, with a more immune-rich TME (via IF). PPx epithelia, in contrast, are more metabolically and translationally active, with a mesenchymal/fibrotic TME. Pre-cancerous epithelia in PPx exhibit a presence of aggressiveness, marked by increased EMT signaling and complement activity. We identify distinct epithelial gene signatures for PPx and GPx that can accurately classify diagnostic samples and likely inform therapy.