PDCD1 and ovarian carcinoma: TIGIT/CD226 receptor pair, whose relationship is analogous to the CTLA-4/CD28 receptor pair, fulfils the role of co-inhibitory or co-stimulatory function.52 TIGIT can inhibit NK cell-mediated tumour killing and induce immunosuppressive DCs.53 The dual blockade of the TIGIT and PD-1 axis stimulates the effective T cells and NK cells in ovarian cancer patients.54 The most promising anti-TIGIT mAbs include tiragolumab (GO30103), zimberelimab (AB122), and tislelizumab (BGB-A317).