PDCD1 and cancer: Immunotherapy, particularly PD‐1/PD‐L1 blockade, has shown efficacy in a variety of cancers.36, 37, 38, 39, 40 However, not all patients have derived clinical benefits from PD‐1/PD‐L1 therapy, and the molecular mechanisms underlying the regulation of T cells in GIST are not elucidated.