晚期胃癌预后较差，传统化疗疗效有限，未能满足患者治疗需求。免疫检查点抑制剂（immune checkpoint inhibitors，ICIs）已改变晚期胃癌治疗格局，其中程序性死亡受体-1（programmed death-1，PD-1）抑制剂联合化疗、PD-1抑制剂联合曲妥珠单抗及化疗已分别成为人表皮生长因子受体2（human epidermal growth factor receptor 2，HER-2）阴性或阳性晚期胃癌一线治疗选择，其他免疫检查点分子抑制剂和癌症疫苗、过继性细胞输注等疗法的研究均在进行中。如何通过生物标志物筛选免疫治疗最佳获益人群，是近期研究热点。除肿瘤突变负荷、程序性死亡配体-1（programmed death-ligand 1，PD-L1）表达、微卫星不稳定性等，新兴标志物如循环肿瘤DNA、肠道微生物组学和细胞因子等均值得关注。本文就晚期胃癌一线免疫治疗的临床研究进展及展望进行综述。 Abstract: Due to the limited efficacy of chemotherapy, the prognosis of patients with advanced gastric cancer remains poor. There is still a need to optimize the treatments to improve the survival of these patients. Immune checkpoint inhibitors (ICIs) have changed the treatment strategies of advanced gastric cancer. Programmed death-1 (PD-1) inhibitor combined with chemotherapy with or without trastuzumab have brought new treatment options for HER2-negative and HER2-positive advanced gastric cancer patients, respectively. There are a series of ongoing studies to evaluate the efficacy of new ICIs, cancer vaccines, and adoptive cell immunotherapies. Moreover, screening the best beneficiaries of immunotherapy through biomarkers has become one of the hot research areas in gastric cancer. Besides tumor mutation burden (TMB), programmed death-ligand 1 (PD-L1) and microsatellite instability, emerging data suggested that circulating tumor DNA, gut microbiome and cytokines might also be the predictive biomarkers relevant to the effect of immunotherapy. In this review, we will summarize the results of the pivotal first-line immunotherapy clinical trials and biomarker exploratory studies in advanced gastric cancer.