CD274 and head and neck squamous cell carcinoma: We then explored the TLS distribution in HNSCC-TC 1–5 and found the highest level of TLSs in HNSCC-TC 5, followed by HNSCC-TC 3, 2, 4, and 1, showing identical trends with PD-L1 expression but not TMB distribution, which further confirmed the co-expression of TLSs and immune checkpoints (Fig. 7F).