Analysing tumour CD8+ T cells, we found that treatment with Fc-inert anti-TIGIT antibodies increased the expression of genes associated with effector differentiation and exhaustion such as Pdcd1, Lag3 and Tox, while expression of those same genes was reduced by treatment with Fc-active IgG2a anti-TIGIT antibodies (Extended Data Fig. 5d). Here, PDCD1 is linked to neoplasm.