The microbes in the gut (the gut microbiome) are a key part of our immune system. The use of antibiotics disrupts the gut microbiome and has been shown to make people susceptible to various illnesses. In this study, researchers investigated how antibiotics may influence response to treatment and clinical outcomes in people with metastatic renal cell carcinoma (RCC) taking various drug treatments, including immune checkpoint inhibitors.
The researchers looked at two groups of patients: patients attending the hospital for treatment with immune checkpoint inhibitors (146 patients) and patients taking part in phase II/III clinical trials (4,144 patients) and being treated with interferon-α, mTOR inhibitors, and VEGF targeted therapy. Antibiotic use was considered from 8 weeks before to 4 weeks after the start of anticancer treatment. Progression-free survival and overall survival were assessed.
This study demonstrated that antibiotic use was associated with worse clinical outcomes in patients with metastatic RCC treated with either immune checkpoint inhibitors or cytokines. Antibiotic use did not appear to impact survival in patients treated with VEGF targeted therapy (e.g. sunitinib, pazopanib) without prior cytokines or mTOR inhibitors (e.g. everolimus).
The researchers concluded the following implications of this study:
- It is important to manage antibiotic use before and during treatment with immune checkpoint inhibitors, such as nivolumab, pembrolizumab and ipilimumab, since prescribing of antibiotics may affect subsequent clinical outcomes
- Analysis of stool samples for changes in the gut microbiome during treatment is warranted
- This may lead to a deeper understanding of the gut microbiome and lead to strategies to optimise the efficacy and reduce toxicity of immune checkpoint inhibitors.