Efficacy and safety of PD-1/PD-L1 inhibitors for relapsed/metastatic nasopharyngeal carcinoma: A systematic review and meta-analysis

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A systematic evaluation was performed to investigate the efficacy and safety of programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors in relapsed/metastatic nasopharyngeal carcinoma (RM-NPC) treatment. A comprehensive literature retrieval was performed across PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang, VIP, and CBM to identify cohort studies or randomized controlled trials (RCTs) addressing the efficacy and safety of PD-1/PD-L1 inhibitors in RM-NPC from database establishment to June 2025. Literature screening and data extraction were conducted independently according to inclusion and exclusion criteria. Two reviewers assessed the quality and bias risk of included studies. Meta-analysis and sensitivity analysis were performed using Revman 5.4.1 for outcome data, and bias risk was evaluated via funnel plots. Eleven articles (8 studies and 1701 patients) were included. The trial group showed higher complete response (CR, RR=1.40, 95 %CI 1.08–1.81, P = 0.01) and objective response rates (ORR, RR=1.16, 95 %CI 1.07–1.25, P = 0.0002). While median overall survival (OS) and 1-year OS did not differ, 2-year OS was higher (RR=1.24, 95 %CI 1.08–1.43, P = 0.002). Median progression-free survival (PFS) was prolonged (HR=0.50, 95 %CI 0.39–0.63, P < 0.001), with higher PFS rates (high heterogeneity). Post-treatment CD3 + (MD=2.61, 95 %CI 0.72–4.49, P = 0.007), CD8 + (MD=2.18, 95 %CI 1.17–3.19, P < 0.01), and undetectable EBV DNA (OR=4.75, 95 %CI 2.23–10.13, P < 0.01) were higher in the trial group. Grade ≥ 3 adverse events did not differ (OR=1.20, 95 %CI 0.88–1.65), but immune-related adverse reactions were more frequent (OR=2.70, 95 %CI 1.86–3.91, P < 0.001), and mortality was lower (OR=0.18, 95 %CI 0.04–0.87, P = 0.03). PD-1/PD-L1 inhibitors improve CR, ORR, immune function, 2-year OS rate, and EBV clearance, prolong PFS, and reduce mortality in RM-NPC, with manageable safety despite increased immune-related risk.