The following is a summary of “Impact of Antibiotic Exposure Before Immune Checkpoint Inhibitor Treatment on Overall Survival in Older Adults With Cancer: A Population-Based Study,” published in the June 2023 issue of Oncology by Eng, et al.
For a retrospective cohort study at the population level, researchers sought to investigate the impact of antibiotic exposure prior to initiating immune checkpoint inhibitor (ICI) treatment on overall survival (OS) in older adults with cancer.
They identified patients aged 65 years or older who had started treatment with ICIs between June 2012 and October 2018 in Ontario, Canada, using systemic therapy administration data. Through deterministic linkage to other healthcare databases, we obtained covariates and antibiotic prescription claim data for both 1 year and 60 days before the initiation of ICI therapy. They employed multivariable Cox models to assess the association between antibiotic exposure and OS.
Among the 2,737 patients with cancer who received ICIs, 59% and 19% had received antibiotics within 1 year and 60 days before ICI therapy, respectively. The median OS was 306 days. Any antibiotic exposure within 1 year before ICI therapy was found to be associated with worse OS (adjusted hazard ratio [aHR], 1.12; 95% CI, 1.12 to 1.23; P = .03). In the analysis of antibiotic classes, exposure to fluoroquinolones within 1 year (aHR, 1.26; 95% CI, 1.13 to 1.40; P < .001) or 60 days before ICI therapy (aHR, 1.20; 95% CI, 0.99 to 1.45; P = .06) was associated with worse OS. A dose effect was observed based on the total weeks of antibiotic exposure over 1 year (aHR, 1.07 per week; 95% CI, 1.03 to 1.11; P < .001) and 60 days (aHR, 1.12 per week; 95% CI, 1.03 to 1.23; P = .01).
In the population-level study, they observed that antibiotic exposure, particularly fluoroquinolones, before initiating ICI therapy was linked to worse OS in older adults with cancer. Implementing interventions aimed at modifying the gut microbiome to enhance immunogenicity may hold promise for improving outcomes in patients receiving ICIs after prior antibiotic exposure.
Source: ascopubs.org/doi/full/10.1200/JCO.22.00074
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