Predictive value of PD-L1 expression and dMMR/pMMR status for immune checkpoint inhibitor combined with chemotherapy in advanced/recurrent endometrial cancer: a meta-analysis

BACKGROUND: Advanced/recurrent endometrial cancer (EC) poses a significant therapeutic challenge. Immune checkpoint inhibitor (ICI) combined with chemotherapy (CT) represents a promising first-line approach, yet the predictive value of deficient/proficient mismatch repair (dMMR/pMMR) status and PD-L1 expression in therapeutic efficacy remains unclear. This study aimed to systematically evaluate the predictive value of dMMR/pMMR status and PD-L1 expression for progression-free survival (PFS) and overall survival (OS) in patients with advanced/recurrent EC treated with ICI + CT. METHODS: A systematic review and meta-analysis of randomized controlled trials (RCTs) from four databases (PubMed, Embase, Cochrane Library, Web of Science) was performed. PFS and OS were synthesized as hazard ratios (HRs) with 95% confidence intervals (CIs) using Review Manager 5.4. RESULTS: Five RCTs (2,707 patients) were included in this meta-analysis. Compared with CT alone, ICI + CT significantly improved PFS in all subgroups: dMMR (HR = 0.36, 95% CI:0.28–0.45, P < 0.00001), pMMR (HR = 0.78, 95% CI:0.70–0.87, P = 0.009), PD-L1-positive (HR = 0.52, 95% CI:0.38–0.70, P < 0.0001), and PD-L1-negative (HR = 0.66, 95% CI:0.44–0.98, P = 0.04). For OS, only the dMMR subgroup showed a significant benefit (HR = 0.41, 95% CI:0.28–0.61, P < 0.00001), with no improvement observed in pMMR patients (HR = 0.88, 95% CI:0.73–1.07, P = 0.20). CONCLUSION: For advanced/recurrent EC, ICI + CT enhanced PFS across dMMR/pMMR and PD-L1 expression subgroups, with OS benefit apparently confined to dMMR patients and not observed in pMMR patients. These results present the clinically valuable predictive value of MMR status for ICI + CT efficacy and suggest that PD-L1expression did not influence the benefit of ICI on patient PFS, which deserve high clinical attention. TRIAL REGISTRATION: https://inplasy.com/inplasy-2026-03-0015/ , identifier INPLASY202630015.