While the recent preclinical studies showed increased Tregs population in immune ICIs and RT-treated recurrent tumors,172 the use of anti-CD25 antibody increased Teff/Treg ratio and improved ICI efficacy.173 Programmed death-ligand 1 (PD-L1), also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1) has recently been associated with resistance to immunotherapy and immune escape in multiple cancers, including HNSCC. This evidence concerns the gene CD274 and cancer.