Endosymbionts mediate the effects of antibiotic exposure in the tramp ant Cardiocondyla obscurior

BackgroundImmune checkpoint inhibitors (ICIs) have been shown to improve patients‘ clinical outcomes in a variety of cancers, but with variable efficacy. Prior research has also suggested that systemic antibiotic (ABX) exposure may impact the intestinal microbiota and result in suboptimal ICI treatment outcomes. Our team published a systematic review and meta-analysis showing that ABX use could indeed decrease the survival of patients diagnosed with non-small-cell lung cancer (NSCLC) and treated with ICIs.1 The present abstract aims at updating this meta-analysis by incorporating new studies that have been published in the period ranging from September 2019 to August 2020.MethodsMedline (through PubMed), the Cochrane Library and major oncology conferences proceedings were systematically searched to identify studies assessing the impact of ABX use on the clinical outcomes of NSCLC patients treated with ICIs. Studies were found eligible for inclusion when they mentioned a hazard ratio (HR) or Kaplan–Meier curves for overall survival (OS) or progression-free survival (PFS) based on antibiotic exposure. Pooled HRs for OS and PFS and HRs for OS and PFS according to different time windows for ABX exposure were calculated.Results6 eligible new studies were identified between September 2019 and August 2020 while 3 other studies were updated with new information. Altogether, 27 studies reported data for OS (6,436 patients, 826 of whom coming from new studies) and 24 for PFS (3,751 patients, 786 of whom coming from new studies). The pooled HR was 1.75 (95% confidence interval [CI]: 1.38–2.23) for OS and 1.57 (95% CI: 1.28–1.92) for PFS, confirming a significantly reduced survival in patients with NSCLC exposed to ABX. The detailed analysis in subgroups based on the time window of exposure (figure 1, figure 2) suggests that the deleterious effect of ABX is stronger when the exposition happens shortly before and after the initiation of the ICI treatment.Abstract 671 Figure 1Forest plot of hazard ratios for overall survival of patients diagnosed with NSCLC and exposed to antibiotics versus not exposed to antibiotics, according to the time window of antibiotic exposureAbstract 671 Figure 2Forest plot of hazard ratios for progression-free survival of patients diagnosed with NSCLC and exposed to antibiotics versus not exposed to antibiotics, according to the time window of antibiotic exposureConclusionsThe update of the meta-analysis confirms the previously reported deleterious effect of ABX on ICI treatment outcomes, taking into account the latest publications in the field. The topic deserves further research to uncover if the effect will stand with 1st line use of ICI together with chemotherapies and/or other approved combinations, elucidate the mechanisms at stake and improve care of patients.ReferencesLurienne L, Cervesi J, Duhalde L, de Gunzburg J, Andremont A, Zalcman G, et al. NSCLC immunotherapy efficacy and antibiotic use: a systematic review and meta-analysis. J Thorac Oncol 2020;15:1147–1159.

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