Impact of Antibiotic on Efficacy and Adverse Reactions of Chemoimmunotherapy in Non-small Cell Lung Cancer Patients: A Retrospective Cohort Study.

Background: This study aimed to evaluate the impact of antibiotic exposure on efficacy and adverse reactions in non-small cell lung cancer (NSCLC) patients receiving chemoimmunotherapy, and to explore any specific associations on the basis of antibiotic class.

Methods: A retrospective study was conducted on NSCLC patients who received chemoimmunotherapy in two Shandong hospitals between January 2018 and October 2023. The association between antibiotic exposure and progression-free survival (PFS), overall survival (OS), objective response rate (ORR) and incidence of immune related adverse reactions (irAE) of patients were evaluated.

Results: Of the 316 patients, 134 (42.41%) received antibiotics (ATB group), and 182 (57.59%) did not (N-ATB group). There was no significant difference in PFS (aHR = 1.009, 95% CI: 0.770-1.323; p = 0.946) or OS (aHR = 1.420, 95% CI: 0.986-2.047; p = 0.060) between ATB and N-ATB groups. The impact on efficacy was related to the type of antibiotic. β-Lactams (aHR = 1.737, 95% CI: 1.148-2.629; p = 0.009), in particular β-lactam/β-lactamase inhibitor combinations (BLBLIs) (aHR = 1.885, 95% CI: 1.207-2.944, p = 0.005) were associated with poorer OS. However, quinolones (aHR = 1.192, 95% CI: 0.861-1.650; p = 0.291) were not associated with OS. The incidence of irAEs was not significantly different between ATB and N-ATB groups (p = 0.073), but was higher with BLBLIs (p = 0.013).

Conclusions: In NSCLC patients receiving chemoimmunotherapy, no significant difference was observed in efficacy and incidence of irAEs between the ATB and the n-ATB groups. In antibiotic class analysis, β-lactams and specifically BLBLIs were observed to be associated with worse OS.