CD274 and head and neck squamous cell carcinoma: More recently, a CRISPR-based synthetic lethality screen identified an intrinsic role of PD-L1 in conferring ferroptosis resistance in HNSCC, mediated through transcriptional activation of SOD2; PD-L1-deficient cells displayed heightened susceptibility to ferroptosis and immunogenic cell death, suggesting that intrinsic PD-L1 functions shape ferroptosis vulnerability beyond immune checkpoint signaling [88].