Early CD201-high cancer-associated fibroblasts shape immunosuppression and suggest a therapeutic opportunity in triple-negative breast cancer.

Cancer-associated fibroblasts (CAFs) shape the immune microenvironment in triple-negative breast cancer (TNBC), yet widely used CAF markers such as fibroblast activation protein (FAP) are not CAF-specific and are predominantly upregulated in activated stroma, limiting early-window stratification. Reasoning that tumors hijack tissue-repair programs, we investigated CD201 (PROCR), a marker of multipotent fibroblast progenitors that can diverge toward inflammatory and myofibroblastic lineages, as an earlier stromal state. Single-cell RNA sequencing of 10 TNBC patients, supported by cross-species analyses, delineated a CAF subset with high CD201 expression (CD201hi CAFs) that pseudotime placed at the beginning of the CAF differentiation continuum, with progenitor-like, immunoregulatory and distinct metabolic programs. From genes associated with this state, we derived a nine-gene prognostic signature achieving a C-index of 0.759 across independent TNBC cohorts, with variable performance across cancer types. Tumors with higher CD201 expression or risk scores exhibited greater immune-cell infiltration together with upregulated checkpoint programs (CTLA-4, PD-1), consistent with recruitment accompanied by functional restraint. In-silico docking and molecular dynamics nominated quercetin as a putative CD201 ligand, and in an orthotopic 4T1 model the quercetin-rosmarinic acid combination outperformed monotherapies in tumor-growth inhibition (∼78% vs ∼54-59%) and extended median survival (29.5 vs 18.5-21.5 days). Collectively, these data nominate CD201hi CAFs as an early, therapeutically relevant stromal state in TNBC and provide a validated risk signature for biomarker-guided stratification and study design; prospective, biophysical, and multi-model confirmation of target engagement is warranted to enable early-window interventions.