medwireNews: Antibiotic use does not impair the survival of patients with metastatic non-small-cell lung cancer (NSCLC) treated with first-line chemoimmunotherapy, suggest results from an international retrospective study.
These findings are in contrast to a prior analysis of data from landmark clinical trials showing antibiotic use to be associated with worse survival outcomes in patients receiving immune checkpoint inhibitors alone, note the researchers.
They therefore write in the Annals of Oncology: “[P]atients with PD-L1 positive NSCLC and [prior antibiotic therapy] exposure might be best served by chemo-immunotherapy combinations to avoid the detrimental effect of antibiotics.”
The study included data for 302 patients with stage IV NSCLC (58.4% PD-L1 ≥1 of 274 evaluable for PD-L1 expression) who received first-line chemoimmunotherapy across eight institutions between December 2014 and October 2020.
In total, 15.6% were given an antibiotic – most commonly beta-lactams and cephalosporins in 40.4% and 21.3%, respectively – within 30 days of chemoimmunotherapy initiation, primarily for respiratory tract infections (44.7%) and infection prophylaxis (27.7%).
After a median 15.4 months of follow-up, overall survival and progression-free survival did not significantly differ between patients with and without prior exposure to an antibiotic, at a median 11.2 versus 16.6 months and 5.6 versus 6.3 months, respectively.
Objective response was evaluable for 239 participants and the rates were a comparable 42.6% and 57.4% for those with versus without prior antibiotic use.
These findings were confirmed in multivariable analyses accounting for factors such as age, sex, smoking status, and PD-L1 expression levels, which did not show a significant association between antibiotic use and any of the clinical outcomes, report the study authors.
And they write: “The stratification potential for [prior antibiotic] status and the interplay between gut microbiome diversity, systemic antibiotics and chemotherapy-enhanced anti-cancer immunity deserves further mechanistic investigation in prospective studies.”
The study also indicated that patients given antibiotics concurrently with chemoimmunotherapy had similar survival outcomes to those who were not. Thus, Alessio Cortellini (Imperial College London, UK) and colleagues say that “there should be no concern in offering [concurrent antibiotic therapy] during chemo-immunotherapy when needed.”
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