CD274 and neoplasm: Moreover, high-density infiltration of CD8-positive tumor-infiltrating lymphocytes (TILs) within the tumor has been shown to be significantly associated with improved progression-free survival (PFS) and overall survival (OS), indicating that SNSCC is an immunoresponsive tumor and that inhibiting the PD-1/PD-L1 pathway may confer therapeutic benefit [14,16].