With respect to the investigation of predictive markers for immunotherapy, a study retrospectively evaluating R/M HNSCC patients treated with anti-PD-1/PD-L1 ICI treatment showed that increased intratumoral CD8+ T cell infiltration and an increased CD8+ T cell/Treg ratio were linked to a better treatment response [84]. Here, CD274 is linked to head and neck squamous cell carcinoma.