CD274 and head and neck squamous cell carcinoma: For example, PD-L1 expression by tumor and/or antigen-presenting cells (APCs), particularly macrophages and myeloid dendritic cells, has been correlated with increased patient response toward anti-PD-L1/PD-1 therapy in patients with colorectal cancer [214], HNSCC [215], melanoma [165,170], NSCLC [172,215] and RCC [214].