PDCD1 and cancer: Expression of CD155 and CD112 is elevated in some human cancers,100,117–124 and TIGIT and CD96 are upregulated on T and NK cells in a series of malignancies, which is associated with poor prognosis and poor response to anti-PD-1 therapy, whereas benefit is observed with TIGIT and/or CD96 blockade.117,118,125–131 Anti-TIGIT mAb is the major agent type targeting this pathway, with fewer anti-CD96, anti-CD112R, and anti-CD155 mAbs (and recombinant poliovirus agent for CD155) available (Table 1 and Supplementary Table 1).