Efficacy and safety of immune checkpoint inhibitors plus platinum-etoposide vs. platinum-etoposide in the first-line treatment of extensive-stage small cell lung cancer: a systematic review and a meta-analysis

Background: Currently, immune checkpoint inhibitors (ICIs) combined with platinum-etoposide (EP) are gradually becoming the first-line standard treatment for extensive-stage small cell lung cancer (ES-SCLC). This meta-analysis aims to compare the efficacy and safety of ICIs combined with EP vs. EP alone in the first-line treatment of ES-SCLC. Methods: We searched PubMed, Embase, and Cochrane Library databases for phase II/III randomized controlled trials (RCTs) that met inclusion criteria from January 2016 to November 2023. Outcome measures included progression-free survival (PFS), overall survival (OS), objective response rate (ORR), treatment-related adverse events (TRAEs), treatment-related serious adverse events (TRSAEs), and immune-related adverse events (IRAEs). The effect analysis statistics of the outcome indicators were expressed with hazard ratio (HR) and odds ratio (OR) and their 95% confidence interval (CI). Results: This study included nine RCTs with a total of 4,711 patients. Compared to EP, ICIs plus EP improved patients' PFS (HR =0.71; 95% CI: 0.64-0.79; P<0.001), OS (HR =0.79; 95% CI: 0.74-0.84; P<0.001), and ORR (OR =1.27; 95% CI: 1.12-1.44; P=0.001), but increased the incidence of adverse events (AEs): TRAEs (OR =1.45; 95% CI: 1.20-1.76; P<0.001), IRAEs (OR =3.97; 95% CI: 2.49-6.32; P<0.001), and grade 3-4 IRAEs (OR =6.17; 95% CI: 2.36-16.15; P<0.001). However, there was no significant difference in the incidence of grade 3-4 TRAEs (OR =1.05; P=0.54), TRSAEs (OR =1.40; P=0.13), and grade 3-4 TRSAEs (OR =1.17; P=0.72). Subgroup analysis found that patients with brain metastasis did not benefit from ICIs combined with EP therapy, and patients with programmed cell death ligand 1 (PD-L1) expression >= 1% had poorer survival benefits compared to patients with PD-L1 expression <1%. Conclusions: In the first-line treatment of ES-SCLC, compared to EP chemotherapy, ICIs with EP can benefit patients in terms of PFS, OS, and ORR, but it will increase the occurrence of AEs.