Survival impact of immune-related adverse events in extensive stage small cell lung cancer patients: a retrospective cohort study

Prior research indicates a connection between immune-related adverse events (irAEs) and improved progression-free survival (PFS) and overall survival (OS) in non-small cell lung cancer. However, limited data exists for extensive stage small cell lung cancer (ES-SCLC). This study included all ES-SCLC patients who received at least one dose of an immune checkpoint inhibitor between 2 January 2011 and 4 July 2022 using a large retrospective registry from a single institution. PFS and OS were right-censored at the date of last follow-up and were estimated using the Kaplan-Meier method. Differences in PFS and OS between irAE groups were assessed using Cox proportional hazards models. Among 245 patients with ES-SCLC; 56 (23%) experienced irAEs, 24 (42.9%) of which were high-grade (3-4). High-grade irAEs occurred at a median of 1.2 months (interquartile range [IQR] 0.45-2.5), while low-grade irAE occurred at 2.8 months (1.3-5.2). PFS was significantly longer among any irAE vs none (HR = 0.49; [95%CI 0.32-0.77]) as was OS (HR = 0.49; [95%CI 0.34-0.72]). In ES-SCLC patients treated with immunotherapy, those who experienced any irAE demonstrated a two-fold increase in both PFS and OS compared to those without an irAE. This is consistent with other tumor primaries.