Safety and efficacy of carboplatin-etoposide plus an immune checkpoint inhibitor and with primary prophylactic pegylated granulocyte colony-stimulating factor in patients with small cell lung cancer

Neutropenia and febrile neutropenia (FN) are important adverse events during chemotherapy for extensive-stage small cell lung cancer (ES-SCLC). Primary prophylactic administration of granulocyte colony-stimulating factor (G-CSF) may help prevent these toxicities, but evidence remains limited. We retrospectively reviewed individuals with ES-SCLC who received platinum plus etoposide with an immune checkpoint inhibitor (ICI) at Kyushu University Hospital between December 2019 and June 2024. Patients were divided into two groups according to whether they received primary prophylactic pegylated (PEG) G-CSF. Clinical data and treatment outcomes were compared between the two groups. Thirty-six patients were analyzed (PEG G-CSF group, n = 19; non–PEG G-CSF group, n = 17). Incidence of grade 4 neutropenia (26% vs. 76%, p = 0.0037) and frequency of platinum-etoposide dose reductions in the second cycle (42% vs. 76%, p = 0.039) were lower in the PEG G-CSF group than in the non–PEG G-CSF group. Objective response rate was similar for the two groups (74% for PEG G-CSF vs. 76% for non–PEG G-CSF). Median progression-free survival was 4.4 versus 5.7 months (hazard ratio [HR] of 1.07 with a 95% confidence interval [CI] of 0.53–2.15, p = 0.90) and median overall survival was 19.2 versus 11.5 months (HR of 0.61 [95% CI, 0.26–1.41], p = 0.20) for the PEG G-CSF and non–PEG G-CSF groups, respectively. Primary prophylactic PEG G-CSF reduced the incidence of severe neutropenia while maintaining treatment intensity in ES-SCLC patients receiving first-line platinum plus etoposide with an ICI.