Two studies evaluated the impact of PD-1 and TIGIT co-inhibition on cancer vaccine therapy in tumor-bearing mice; the results showed that the combined blockade of TIGIT and PD-1 reversed T-cell depletion due to upregulated PD-L1 and CD155, showing better anti-tumor effects than using cancer vaccine alone [62,63]. The gene discussed is PDCD1; the disease is neoplasm.