CEACAM5 and astrocytoma (excluding glioblastoma): For example, natural killer (NK) cells acquire carcinoembryonic antigen (CEA) from the surface of CEA-expressing cells via trogocytosis and exhibit inhibited cytolytic activity and dampened degranulation function 158; T cells exposed to tumor-derived exosomes incorporating PD-L1 display suppressed activation in the dLNs 159; and TNT-connected astrocytoma cells may promote tumor progression and resistance to therapy 160.