CD274 and head and neck cancer: In a previous phase Ib trial, pembrolizumab produced an overall response rate of 20% in patients with advanced head and neck cancer, and a subgroup analysis showed a higher response rate (45.5%) in patients with tumours expressing PD-L1 above a cut-off point [88] (1% of staining in tumour cells or stroma) vs. 11.4% in those below the cut-off point.