PDCD1 and neoplasm: This paradoxical effect, wherein CAFs support proliferation even under chemotherapeutic pressure, may reduce the complete response (CR) rate by fostering residual tumor survival between treatment cycles (49).CAFs also remodel the extracellular matrix (ECM), increasing stromal density and rigidity, which limits T cell infiltration and impairs ICI efficacy, particularly PD-1/PD-L1 blockade.