TIGIT and neoplasm: TIGIT is an immune checkpoint within the immunoglobulin superfamily that has recently gained significant attention and is widely expressed on CD8+ tumour-infiltrating lymphocytes (TILs), NK cells, helper T (Th) cells, and Tregs across various cancers, including melanoma, non-small cell lung cancer, colorectal cancer, hepatocellular carcinoma, and gastric cancer (Johnston et al., 2014; Chauvin et al., 2015; Inozume et al., 2016; Thommen et al., 2018; Hu et al., 2020; Xu et al., 2020; Ostroumov et al., 2021).