The safety and efficacy of neoadjuvant PD-1 inhibitor plus chemotherapy for patients with locally advanced gastric cancer: A systematic review and meta-analysis

Background: The extensive utilization of immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD-1) has achieved significant advancements in the treatment of diverse solid tumors. The present meta-analysis aims to evaluate the safety and efficacy of neoadjuvant chemotherapy (NCT) plus PD-1 inhibitor for patients with locally advanced gastric cancer (LAGC). Methods: An electronic search of PubMed, EmBase, and the Cochrane Library was performed to identify the clinical trials of NCT + PD-1 inhibitor vs. NCT in patients with LAGC. The retrieval period extended from the establishment of the corresponding database until April 2024, and meta-analysis was conducted using Stata (version 15) software. Subsequently, direct comparative analysis was used to compare pooled results of neoadjuvant immunochemotherapy (NICT) with NCT. Results: After screening, 6 phase II/III randomized controlled trials (RCTs) and 9 retrospective studies with 2,953 patients were included. In meta-analysis, NICT group demonstrated a significantly higher rate of pathological complete response (pCR) ( P <0.001) and R0 resection ( P =0.001), and a lower 2-year recurrence rate ( P =0.001) compared to the NCT group. The NICT group, however, exhibited a higher incidence of severe treatment-related adverse events (TRAEs) ( P =0.044). Additionally, the NICT and NCT groups exhibited no statistical differences in terms of the number of harvested lymph nodes, the occurrence of total TRAEs and postoperative complications, as well as the duration of postoperative hospitalization. Conclusions: The combination of PD-1 inhibitor + NCT in LAGC patients enhances the likelihood of achieving radical surgery and improves prognosis, albeit to some extent increasing the risk of severe TRAEs. NICT is anticipated to emerge as the preferred neoadjuvant therapy option for patients diagnosed with LAGC.