Interestingly, a systematic review and meta-analysis of 17 studies involving 3190 patients with HNSCC found that a high level of PD-L1 expression exclusively on immune cells were associated with improved survival in patients with localized and locoregionally advanced HNSCC, while its expression on tumour cells was not correlated with survival [49]. The gene discussed is CD274; the disease is head and neck squamous cell carcinoma.