Purpose: In this study, we test the hypothesis that the use of ATB reduces the efficacy of PD(L)1-targeting mAb.
Methods: We included patients with locally advanced, inoperable or metastatic, EGFR wildtype and ALK-negative non-small-cell lung cancer (NSCLC) who received a PD(L)1 targeting mAb (immune checkpoint inhibitor, ICI) between January 2013 and December 2017. The primary study objective was to assess the predictive impact of ATB use within 2 months prior to starting ICI treatment on overall survival from the time of starting ICI treatment (OS-ICI).
Results: 33 out of 218 evaluable patients (15.1%) received ATB within 2 months prior to starting ICI treatment. The use of ATB prior to starting ICI was associated with a lower rate of radiological response (18.2 vs. 28.3%, respectively, P = 0.02). PFS was significantly shorter in patients receiving ATB within 2 months prior to ICI compared to those not receiving ATB (median PFS 1.4 vs. 5.5 months, HR = 2.22, P < 0.01). OS-ICI was significantly shorter in NSCLC patients receiving ATB within 2 months prior to ICI compared to those not receiving ATB (median OS-ICI 1.8 vs. 15.4 months, HR = 2.61, P < 0.01; adjusted HR = 3.73, P < 0.01).
Conclusion: The results of this study suggest that ATB may have a deleterious effect in patients with advanced NSCLC receiving ICI treatment, and more research seems to be justified to explore potential mechanisms.
Keywords: Antibiotics; Checkpoint inhibitors; Gut microbiota; Immunotherapy; Lung cancer.