Immune biomarkers of response to immune-checkpoint inhibitors in head and neck squamous cell carcinoma

Immune-checkpoint inhibitors (ICI) targeting cytotoxic T-lymphocyte antigen 4 and programmed cell death protein-1 (PD-1) and its ligands, programmed death ligand-1 (PD-L1)/2, have shown a significant and consistent benefit in survival when compared with standard therapies in prospective randomized clinical trials, leading to their regulatory approval in multiple tumor types [1–5].