Fig. 4: Ablation of FAP⁺ cells alters the stromal landscape, rapidly depletes matrix and enhances T cell infiltration.

a Representative (top) and quantification of (bottom) multiplex immunofluorescence images in tumors 1 week (left) and 2 weeks (right) post-treatment with PBS, MigR control or FAP-CAR T cells. First row depicts staining for stromal cell profiles, including FAP (green), α-SMA (red) and PDGFR-α (magenta). Second row depicts staining for ECM components including collagen hybridizing peptide (CHP) that detects remodeled collagen (red) and FN (green). Third row depicts distribution of T cells (CD3, red) and their spatial relationships to tumor cells (PanCK, green) and stromal cells (PDPN, magenta). Nuclei were stained with DAPI (blue). Scale bar: 100 μm. b t-SNE of multi-parametric flow cytometry demonstrating the immune cell profiles based on the gating strategy as depicted in Supplementary Fig. 8, including lymphocyte (left) and myeloid cells (right) in tumors 1 week (Top row) and 2 weeks (bottom row) post-treatment with PBS, MigR control or FAP-CAR T cells. The percentages of indicated immune cell subpopulations in total live cells or CD45.2⁺ cells from tumors for each group of mice quantified based on multi-parametric flow cytometry analysis. Data points are mean ± SD (n = 5 per group) and groups were compared using two-way ANOVA with Tukey’s multiple comparisons tests. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001, and ^****p < 0.0001. a. PDGFRα (post 1 week): PBS vs. FAP-CAR, p = 0.032. PDGFRα (post 2 weeks): PBS vs. FAP-CAR, p = 0.002. Fibronectin (post 1 week): MigR vs. FAP-CAR, p = 0.022. CD3 (post 1 week): MigR vs. FAP-CAR, p = 0.005. PanCK (post 2 weeks): MigR vs. FAP-CAR, p = 0.004. b post 1 week: CD3 PBS vs. FAP-CAR, p = 0.047. CD8 PBS vs. FAP-CAR, p = 0.004, MigR vs. FAP-CAR, p = 0.020. post 2 weeks: Ly6C^lowLy6G⁺ MigR vs. FAP-CAR, p = 0.006. The p values for remaining comparisons are all <0.001 or <0.0001. Source data are provided as a Source Data file.