Promising New Anti-TIGIT Agents: Stealthy Allies in Cancer Immunotherapy

TIGIT (T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain), Vstm3, and VSIG9, are newly recognized immunological checkpoints. They are prominently expressed on CD4+ and CD8+ T cells, tumor-infiltrating lymphocytes (TILs), natural killer (NK) cells, and regulatory T cells (Tregs). The TIGIT (TIGIT) protein is crucial for immune modulation since it diminishes NK cell populations and hinders T cell activity in cancer patients and experimental models. CD155, the principal ligand of TIGIT in humans, has been recognized as a pivotal target for immunotherapy owing to its interaction with TIGIT. CD155 is linked to the efficacy of anti-programmed cell death protein 1 (PD-1) therapy, even without TIGIT expression, underscoring its importance in immune checkpoint suppression. Anti-TIGIT medicines, either independently or in conjunction with anti-PD-1 treatments, have demonstrated potential in augmenting immune responses to malignancies. This review examines the structural and functional characteristics of the TIGIT protein, new developments in anti-TIGIT drugs, and their prospective use in cancer immunotherapy.