Exosomes (30–150 nm), originating from multivesicular bodies via ESCRT-dependent and independent pathways, are enriched in HNSCC with markers like ALIX, TSG101, and tetraspanins, and play a central role in immune suppression through PD-L1 delivery (5, 20, 21). This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.