Do Antibiotics Affect Response to Immune Checkpoint Inhibitors?

November 20, 2019 by Elisa Becze BA, ELS, Editor

Receiving antibiotics in the 30 days prior to starting immune checkpoint inhibitor treatment was associated with significantly reduced median overall survival, according to findings from a study published in JAMA Oncology ( However, antibiotic use during treatment had no effect on survival.

Researchers looked at antibiotic therapy in 196 patients with non-small cell lung cancer, melanoma, and other tumor types who had received immune checkpoint inhibitor treatment. Prior antibiotic use (defined as within 30 days before checkpoint inhibitor administration) was associated with a median overall survival of 2 months, compared to 26 months for patients who had not received prior antibiotics (hazard ratio [HR] = 7.4, p < 0.001). Conversely, concurrent use of antibiotics demonstrated no difference in overall survival (HR = 0.9, p = 0.76).

The findings were consistent regardless of cancer type, and the researchers also found that patients who had received prior antibiotic treatment were more likely to discontinue immune checkpoint inhibitor treatment because of disease progression and were more likely to die from disease progression while on therapy.

The researchers theorized that the findings may indicate “a potential ‘priming’ effect of prior antibiotics on patients’ anticancer immunity” and concluded that “clinicians should carefully weigh the pros and cons of prescribing broad-spectrum antibiotics prior to immune checkpoint inhibition treatment.”

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