On the other hand, in untreated tumors, the density of pro-stemness CAFs, such as α-SMA−PDGF-Rα+IL-6+ iCAFs in PDAC and CD10+GPR-77+ CAFs in breast cancer and NSCLC (71, 72), can serve as a companion diagnostic to guide the selection of patients for anti-CAF/CSC therapies, especially those targeting the IL-6 and/or the IL-8 paracrine signaling pathways. This evidence concerns the gene CXCL8 and breast cancer.