PDCD1 and neutropenia: In terms of hematologic toxicity, both the Chemo + PD-1 regimen (RR, 1.65; 95%CI, 1.25–2.2) and the Chemo + PD-L1 regimen (RR, 1.58; 95%CI, 1.19–2.12) exhibited a higher risk of severe neutropenia compared with the Chemo + CTLA-4 regimen.