PDCD1 and gastric cancer: Chromogenic-based mIHC was used for the determination of the clinicopathological significance of PD-1, LAG3, and TIM3 markers in stage II/III gastric cancer patients [34] and for the identification the phenotypes and spatial profiles of intratumoural PD-1+ helper T cells associated with the prognosis of head and neck squamous cell carcinoma (HNSCC) [35].