Besides, two clinical trials demonstrated that a combination treatment strategy involving anti-PD1 antibody along with trastuzumab and chemotherapy provides enhanced clinical efficacy and safety for patients with metastatic HER-2-positive GC (Janjigian et al. 2020; Janjigian et al. 2021b; Lee et al. 2022). This evidence concerns the gene ERBB2 and gastric cancer.