Antibiotics and outcomes of cancer immunotherapy: An updated meta-analysis and clinical applications.

In 30 seconds

This updated meta-analysis examined antibiotic exposure and outcomes among 97,850 patients with cancer treated with immune checkpoint inhibitors (ICI), drawing on 116 cohorts. Antibiotic exposure was significantly associated with poorer survival: overall survival HR 1.49 (95% CI: 1.34-1.65) and progression-free survival HR 1.44 (95% CI: 1.31-1.58). The review also discusses how antibiotic-related gut microbiome disruption may contribute to ICI resistance and considers stewardship and microbiome-focused approaches. These findings indicate an association, not proof that antibiotics cause worse outcomes.

Key findings

• Across 116 cohorts and 97,850 ICI-treated patients, antibiotic exposure was associated with worse overall survival (HR: 1.49, 95% CI: 1.34-1.65).
• Antibiotic exposure was associated with worse progression-free survival (HR: 1.44, 95% CI: 1.31-1.58).
• The review describes antibiotic-induced gut dysbiosis as a potential contributor to ICI resistance.

Why it matters

Antibiotic exposure is common among patients receiving ICI, and this meta-analysis links it with poorer survival outcomes. The findings highlight the gut microbiome as a potentially relevant factor in immunotherapy and support attention to antibiotic stewardship and microbiome-focused research, while the association alone cannot establish that antibiotics cause reduced treatment benefit.

What to keep in mind

The meta-analysis combines cohort evidence, so the reported associations do not establish causation; the abstract does not describe adjustment for differences among cohorts.