尽管已经分析了PD-1 / PD-L1抑制剂与化疗相比单独化疗的疗效和安全性，但对PD-L1阳性晚期胃或胃食管交界处癌症（GC / GEJC）患者的结局尚未进行深入研究。本系统评价和荟萃分析旨在比较PD-1 / PD-L1抑制剂与PD-1 / PD-L1抑制剂联合化疗相比单独化疗对PD-L1阳性晚期GC / GEJC患者的疗效和安全性，以期为GC / GEJC的临床治疗提供更精确的指导。在这次荟萃分析中，从数据库的建立到2022年6月，我们搜索了PubMed，Embase和Cochrane Library。该调查纳入了化疗对照组患者接受化疗和实验组患者接受PD-1 / PD-L1抑制剂或PD-1 / PD-L1抑制剂联合化疗的随机对照试验（RCT）。排除了信息不完整的调查、无法提取信息的研究、重复的文章、动物研究、综述文章和系统综述。综合结果表明，化疗联合免疫疗法可以延长PD-L1阳性晚期GC / GEJC患者的总体生存期，而PD-1 / PD-L1抑制剂单独使用或与化疗联合使用的无进展生存期比仅化疗的效果都有所提高。然而，与化疗相比，PD-1 / PD-L1抑制剂在PD-L1阳性患者中并没有显著增加客观反应率（ORR），但与化疗联合使用，它们可以改善ORR。综合结果还显示，在PD-L1阳性患者中，与化疗相比，PD-1 / PD-L1抑制剂治疗的稳定疾病（SD）和进展性疾病（PD）率更高。此外，在PD-L1阳性患者中，与仅化疗相比，PD-1 / PD-L1抑制剂单独使用或与化疗联合使用可以延长总体生存期（OS）。然而，在PD-L1阳性患者中，仅有PD-1 / PD-L1抑制剂与化疗相比可以延长无进展生存期（PFS），但与化疗联合使用时，PD-L1阳性患者的OS和PFS都比仅化疗组延长。最后，综合结果显示，在PD-L1阳性患者中，接受PD-1 / PD-L1抑制剂的不良事件发生率明显低于仅接受化疗的患者。总之，PD-1 / PD-L1抑制剂单独使用或与化疗联合使用可以显著延长患者的生存时间，且副作用较少。然而，CPS的程度可能会影响疗效，因此需要进一步调查。版权：© Su等。

Although the efficacy and safety of programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitor combined with chemotherapy vs. chemotherapy alone has been analyzed, there have been no in-depth studies on the outcomes of patients with PD-L1 positive advanced gastric or gastro-esophageal junction cancer patients (GC/GEJC). This systematic review and meta-analysis focused on comparing the efficacy and safety of PD-1/PD-L1 inhibitors vs. PD-1/PD-L1 inhibitors combined with chemotherapy vs. chemotherapy in PD-L1 positive advanced GC/GEJC patients, aiming to provide more precise guidance for the clinical treatment of GC/GEJC. In this meta-analysis, PubMed, Embase, and Cochrane Library were searched from the establishment of the database till June 2022. Randomized controlled trials (RCTs) in which control patients underwent chemotherapy and experimental group patients underwent PD-1/PD-L1 inhibitors or PD-1/PD-L1 inhibitors combined with chemotherapy were included in this investigation. Investigations without complete information, studies from which information could not be extracted, duplicate articles, animal studies, review articles, and systematic reviews were excluded. The pooled results suggested that chemotherapy combined with immunotherapy prolonged overall survival (OS) in patients with advanced GC/GEJC, while progression free-survival (PFS) with PD-1/PD-L1 inhibitors alone or in combination with chemotherapy were all improved compared with chemotherapy alone. However, PD-1/PD-L1 inhibitors did not significantly increase objective response rates (ORR) in PD-L1-positive patients compared with chemotherapy, but in combination with chemotherapy, they did improve ORR. The pooled results also showed that patients treated with PD-1/PD-L1 inhibitors had higher stable disease (SD) and progressive disease (PD) rates compared to chemotherapy in PD-L1-positive patients. Additionally, in PD-L1-positive patients, PD-1/PD-L1 inhibitors alone or combined with chemotherapy increased OS compared with chemotherapy alone. However, PD-1/PD-L1 inhibitors only prolonged PFS compared with chemotherapy alone in patients with a combined positive score (CPS; 100% of cells were required to be positively stained) for PD-L1, but when combined with chemotherapy, OS and PFS were prolonged in all PD-L1-positive patients compared with chemotherapy alone. Finally, the pooled results showed that the incidence of adverse events of PD-1/PD-L1 inhibitors in PD-L1-zpositive patients was significantly lower than that in patients treated with chemotherapy alone. In conclusion, single agent of PD-1/PD-L1 inhibitor alone or combined with chemotherapy significantly prolongs the survival of patients compared with chemotherapy alone, with fewer adverse effects. However, the degree of CPS may affect efficacy, thus further investigation is required.Copyright: © Su et al.