Moreover, although PD-1/PD-L1 immune checkpoint inhibitors have opened up new ways to treat STAD patients (Kang et al., 2017), the positive response to immunotherapy was also limited to a small number of STAD patients, and the existing predictors of immunotherapy efficacy need to be improved (Salati et al., 2019). The gene discussed is PDCD1; the disease is gastric adenocarcinoma.