Antibiotic Use Does Not Appear to Influence Response to Nivolumab

{Background: Microbiota is known to influence response to anticancer immunotherapy. We examined whether antibiotic usage could impact nivolumab efficacy in patients treated for non-small-cell lung cancer (NSCLC). Patients and Methods: Seventy-four patients with NSCLC were included in this retrospective study. They received nivolumab between 2015 and 2016 (3 mg/kg i.v. q2w). The association between RECIST response and antibiotic usage was determined using Chi-square and Cox proportional hazard model. Results: A total of 17, 21 and 36 patients experienced response, stable disease and progression disease under nivolumab. Only 15 (20.3%) patients were exposed to antibiotic medication in the 3 months before the first nivolumab injection or during treatment. We found a similar response rate for the two populations, without impact of antibiotic exposure (Chi-square test p= 0.75). Moreover, we observed no impact of antibiotic medication on progression-free survival under nivolumab (log-rank test