PDCD1 and head and neck squamous cell carcinoma: ICIs targeting programmed cell death 1 (PD-1) have been approved for the treatment of recurrent and metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) in both first- and second-line settings and a consensus statement on immunotherapy (ICIs) for the treatment of R/M HNSCC has been proposed by the Society for Immunotherapy of Cancer (SITC) [3].