In order to assess tumor-immune interactions in TNBC, CD8+ T cell presence and spatial organization were studied in 236 untreated, primary TNBC using immunohistochemical staining (IHC) of whole slides (Cohort A; for study design see Supplementary Fig. 1 and for clinical details of cohorts see Supplementary Table 1). Here, CD8A is linked to neoplasm.