The results revealed that the over-expression treatment of let-7a/7b combined with CTLA-4 antibody led to the highest IFN-γ content in TILs (Fig. 5h; p < 0.05), indicating that over-expressed let-7a/7b combined with CTLA-4 antibody treatment enhanced the immune activity of TILs, ultimately inhibiting the immune evasion of HNSCC. Here, CTLA4 is linked to head and neck squamous cell carcinoma.