Figure 1.

Treatment-resistant residual disease localizes within a soft ECM niche. (A) Representative hematoxylin and eosin–stained tissue sections of untreated human primary TNBC or residual disease from NAC-treated TNBC. (B) Representative images of brightfield and polarized light PS-stained primary tumor or residual disease tissue sections. (C) Scatterplot showing mean ± SEM of polarized light PS signal for primary tumor (n = 9) and residual disease (n = 7) from three to five fields of view per sample. (D) Representative images of SHG microscopy of tissue sections from human primary and chemotherapy-treated residual TNBC. (E) Scatterplot showing mean ± SEM of collagen coherence calculated from SHG microscopy images of primary tumor (n = 5) and residual TNBC (n = 4). (F) Scatterplot showing mean and SD of AFM elasticity measurements of tumor cell–adjacent ECM from primary tumor (n = 9) and residual disease (n = 7). Values reflect measurements from three to five elasticity maps per sample. (G) Histogram showing distribution of the top 10% of AFM elasticity measurements in each group. All statistical analyses were performed using two-tailed Mann-Whitney U test (*, P < 0.05; ***, P < 0.001). All scale bars are 200 µm.