PDCD1 and cancer: Cancer presents a severe threat to human health, and immunotherapy has made remarkable progress in the disease treatment via mechanisms including the immune checkpoint blockade, for example, the inhibition of programmed cell death 1 (PD‐1)/programmed cell death ligand 1 (PD‐L1) pathway‐mediated tumor immune evasion.[1] However, the efficacy of immunotherapy is often limited by insufficient T cells infiltration in solid tumors.