Comparison of efficacy and safety between PD-1 inhibitors and PD-L1 inhibitors plus platinum-etoposide as first-line treatment for extensive-stage small-cell lung cancer: a multicenter, real-world analysis

Immunotherapy in combination with platinum-etoposide (EP) chemotherapy has been approved as a first-line treatment for extensive-stage small cell lung cancer (ES-SCLC). However, real-world (RW) data regarding the use of immune checkpoint inhibitors (ICIs) in ES-SCLC are lacking. We aimed to assess the differences between programmed death protein 1 (PD-1) inhibitors and programmed death ligand 1 (PD-L1) inhibitors, both in conjunction with EP chemotherapy, as first-line treatment for ES SCLC.

We conducted a real-world, multicenter, retrospective cohort, controlled study to compare the prognosis, efficacy, and safety of PD-1 and PD-L1 inhibitors in ES-SCLC patients when used along with chemotherapy. Each patient received up to six cycles of etoposide, carboplatin, or cisplatin combined with ICI drugs, including PD-1 and PD-L1 inhibitors. The primary endpoints were investigator-assessed progression-free survival (PFS) and overall survival (OS). The secondary endpoints were the investigator-assessed objective response rate (ORR) and disease control rate (DCR) according to the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1).

Between January 2017 and December 2021, 194 patients with ES-SCLC from three clinical centers in a PLA general hospital were included in our study, including 93 patients in the PD-1 group and 101 patients in the PD-L1 group. At the time of data cutoff, progression-free survival in the PD-1 group (median PFS, 6.8 months; 95% CI, 5.3–8.1) was similar to that in the PD-L1 group (median PFS, 6.4 months; 95% CI, 5.5–7.5); the stratified hazard ratio for PFS was 1.12 (95% CI, 0.83–1.53; P = 0.452). The median OS was similar in the PD-1 and PD-L1 groups (15.8 m vs. 17.7 m, P = 0.566); the hazard ratio was 0.90 (95% CI, 0.62–1.30, P = 0.566). The two groups had comparable investigator-assessed confirmed objective response rates (ORR) (76.3% vs. 76.2%). Adverse effect (AE)-related discontinuation occurred in 4 (4.3%) patients in the PD-1 group and 2 (2.0%) patients in the PD-L1 group. Deaths due to AEs of any cause occurred in 2 (2.2%) patients in the PD-1 inhibitor group and 1 (1.0%) patient in the PD-L1 inhibitor group.

Our research revealed that there were no significant differences in efficacy or prognosis between PD-1 inhibitor + EP chemotherapy and PD-L1 inhibitor + EP chemotherapy. The two groups seemed to have comparable safety profiles, but the number of discontinuation or death events was too small to draw a firm conclusion.