Association Between Antibiotic and Outcomes of Chemoimmunotherapy for Extensive-Stage Small Cell Lung Cancer: A Multicenter Retrospective Study of 132 Patients.

Introduction: To evaluate the impact of antibiotic (ATB) exposure on the outcome of chemoimmunotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC).

Methods: In this multicenter retrospective study, 132 patients with ES-SCLC who received chemoimmunotherapy were included from three hospitals in China. Patients receiving ATB within 30 days prior to initiating ICI therapy (p-ATB) and those receiving concurrent ICI therapy until cessation (c-ATB)were compared to those who did not (n-ATB). Progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and immune-related adverse events (irAEs) were assessed. To avoid immortal time bias, c-ATB was analyzed as a time-dependent covariate in the Cox proportional hazards model.

Results: Among the 132 patients, 25 were included in the p-ATB group and 26 in the c-ATB group, while 81 patients were categorized in the n-ATB group. Multivariate analysis revealed no significant differences in PFS (aHR = 1.028, 95% CI: 0.666-1.589, p = 0.900) and OS (aHR = 0.957, 95% CI: 0.549-1.668, p = 0.877) between the p-ATB and n-ATB groups. Similarly, p-ATB had no significant impact on ORR (p = 0.510) or irAEs (p = 0.516). The use of c-ATB had no significant effect on either PFS (aHR: 1.165, 95% CI: 0.907-1.497; p = 0.232) or OS (aHR: 1.221, 95% CI: 0.918-1.624; p = 0.171) by multivariate analysis.

Conclusions: p-ATB has no significant impact on PFS, OS, ORR, or the incidence of irAEs in ES-SCLC patients receiving chemoimmunotherapy. Similarly, c-ATB does not seem to affect PFS or OS.