Although tumours enriched with T cells are associated with better overall survival,16 a stroma-mediated source of immune resistance originating in transforming growth factor beta1 (TGFβ1)-responsive CAFs is linked with poor overall survival and resistance to ICB targeting PD-1/PD-L1.17, 18, 19 However, the origin of CAFs in solid tumors is unclear. The gene discussed is PDCD1; the disease is neoplasm.