PDCD1 and laryngotracheoesophageal cleft: CTLA4, Tim3, Foxp3, GATA3, CD127, TCRab and TIGIT increased in cluster 17 of CD3+ T cell in patients with LC, of which CTLA4 expressed in tumour CD8 T cells associated with PD‐1‐mediated T‐cell dysfunction and efficacy of the checkpoint block immunotherapy in cancers.54, 55