CD155/TIGIT, a novel immune checkpoint in human cancers (Review).

CD155/T cell immunoreceptor with Ig and ITIM domains (TIGIT) is a novel type of immune checkpoint. CD155 is an adhesion molecule that is upregulated during tumor progression and promotes the proliferative and migratory abilities of tumor cells via various pathways. TIGIT, an inhibitory receptor, is mainly expressed on natural killer (NK), CD8+ T, CD4+ T and T regulatory (Treg) cells. CD155 transmits immune signals via interacting with the inhibitory checkpoint receptor TIGIT, thereby inhibiting the function of T and NK cells. Several preclinical studies have supported the use of TIGIT blockade as a monotherapy or combined with other immune checkpoint inhibitors for the treatment of advanced solid malignant tumors. The present review summarized the current knowledge on CD155/TIGIT and the lymphocyte‑mediated inhibitory mechanism of CD155/TIGIT. An in‑depth understanding of the role of CD155/TIGIT in tumors may aid to improve the application of immune checkpoint inhibitors in tumor therapy.