Objective  To explore the effect of chemotherapy administration sequence combined with programmed cell death protein-1 (PD-1) monoclonal antibody on the efficacy and immune-related adverse events (irAEs) in patients with advanced non-small cell lung cancer (NSCLC).

  Methods  The clinical data of 110 patients with advanced NSCLC treated at The First Affiliated Hospital of Zhengzhou University between November 2019 and January 2022 were retrospectively collected. The factors influencing irAEs were analyzed by univariate and multivariate Logistic regression analyses, while those influencing curative effect were analyzed by Kaplan-Meier curve analysis, Log-rank test, and univariate and multivariate Cox regression analyses.

  Results  Treatment with PD-1 monoclonal antibody after 2 days of chemotherapy (sequential treatment group, n=36) significantly prolonged progression-free survival (PFS) compared with PD-1 monoclonal antibody administration on the same day of chemotherapy (simultaneous treatment group, n=74) (17.2 months vs. 11.3 months, respectively; P<0.05). The disease control rate (DCR) was better in the sequential treatment group than in the simultaneous treatment group (94.4% vs. 79.7%, respectively; P=0.045), while the objective response rate (ORR) did not differ significantly (69.4% vs. 51.4%, respectively; P=0.072). The Cox regression analysis showed that cytokerat in 19 fragment (Cyfra21-1) and d-dimer (D-dimer) affected the efficacy of combination therapy (P<0.05). The Logistic regression analysis showed that age and lactic dehydrogenase (LDH) influenced the occurrence of irAEs (P<0.05), while the administration sequence did not significantly affect the occurrence of irAEs (P=0.130).

  Conclusions  Administration sequence influences the efficacy of combination therapy, and patients with advanced NSCLC who receive sequential therapy may experience better efficacy. Age and LDH are negatively correlated with the occurrence of irAEs.