For example, increased TGF‐β enhances antigen‐induced PD‐1 expression on T cells in a SMAD3‐dependent manner,58 drives exclusion of cytotoxic T cells, and impairs acquisition of a Th1 effector phenotype in a cancer metastasis model which has a limited response to anti‐PD‐L1 therapy.59 This evidence concerns the gene SMAD3 and cancer.