Data revealed significantly increased PD-L1 expression levels on THP-1 monocytes in response to 24 hours of hypoxic growth conditions compared to the normoxic control and, furthermore, significantly increased monocytic PD-L1 levels upon incubation with plasma-derived sEVs from HNSCC patients (pre- and post-RCT) compared to sEVs from healthy donors (Figure 4). Here, CD274 is linked to head and neck squamous cell carcinoma.